Waste heat recovery system for producing industrial steam

Abstract

The invention relates to a waste heat recovery system for generating steam for a chemical industrial facility, comprising: a non-continuously operable chemical industrial facility having at least one coolable reactor (2) connected to a primary circuit, wherein the at least one reactor (2) is designed such that, during operation of the reactor (2), a reaction of the reaction mixture takes place, and waste heat generated by cooling of the reactor (2) flows as a first heat transfer fluid through the primary circuit in the form of a heating liquid or in the form of the reaction mixture itself, wherein the primary circuit fluidly connects the reactor (2) to the first heat exchanger (9) in such a way that the first heat transfer fluid is cooled in the first heat exchanger (9) and then returned to the reactor (2) to cool the reactor (2); and a secondary circuit comprising a separate second heat transfer fluid and coupled to the first heat exchanger (9) in such a way that the second heat transfer fluid is heated by the first heat transfer fluid during operation of the at least one reactor (2), the secondary circuit fluidly connects the first heat storage unit (10) downstream of the first heat storage unit (10), the evaporator unit (13) downstream of the first heat storage unit (10), the second heat storage unit (14) downstream of the evaporator unit (13) and the first heat exchanger (9) downstream of the second heat storage unit (14), starting from the first heat exchanger (9), to one another, which completes the secondary circuit, the evaporator unit (13) is designed such that steam is generated and preferably supplied to the at least one compressor (18) during operation of the waste heat recovery system.

Description

[0001] This invention relates to a waste heat recovery system for generating steam for a chemical industrial facility. The waste heat recovery system comprises: a non-continuously operating chemical industrial facility having at least one coolable reactor connected to a primary loop, wherein the at least one reactor is designed such that during operation of the reactor, a reaction mixture occurs, and waste heat generated by cooling the reactor flows through the primary loop as a first heat transfer fluid in the form of a heated liquid or in the form of the reaction mixture itself. The primary loop fluidly connects the reactor to a first heat exchanger in such a way that the first heat transfer fluid is cooled in the first heat exchanger and then returned to the reactor to cool the reactor.

[0002] Waste heat recovery systems are known from existing technologies to improve the efficiency of chemical processes. In the case of batch processes or continuous processes that must be interrupted relatively frequently, for example due to maintenance, there is a common problem that waste heat cannot be recovered during the interruptions. In such cases, a heat storage medium can at least compensate for the gap caused by the specific interruption time. However, the integration of heat storage media is very complex and varies significantly in implementation depending on the specific application.

[0003] KR-2015-0032241A discloses a waste heat recovery system that uses waste heat discontinuously generated from a batch reactor to produce steam as needed. The system includes a heat transfer fluid in the loop that cools the reactor and releases the heat it absorbs from the reactor via heat transfer. Here, heat is transferred either by heating an additional heat transfer fluid (which is then fed into a flash tank to generate steam) or by heat transfer directly at the water level in the flash tank.

[0004] The steam storage device, which serves as a thermal storage unit, is connected downstream of the flash tank's steam outlet so that steam remains available in the event of reactor operation interruption.

[0005] However, this implementation has the following disadvantages: steam occupies a large volume relative to its energy content, and the steam storage device must be correspondingly large. In addition, the steam storage device must also be able to withstand the steam pressure.

[0006] US 2010 / 0319348 A1 discloses a waste heat recovery system belonging to another technical field, in which hot waste fluid (such as flue gas) from a combustion furnace flows through a heat exchanger configured such that energy in the form of heat can be transferred to a heat transfer fluid. The energy in the heat transfer fluid is used to generate electricity. The waste heat recovery system is used for intermittent processes where the generated energy is continuously available. This is achieved through a first heat storage device before energy generation and a second heat storage device after energy generation, where it is possible to store the heat transfer fluid in both devices. In the event of a process interruption, the stored heat transfer fluid flows from the first heat storage device to the second heat storage device to thus generate electricity.

[0007] However, this implementation method has the limitation that energy from the hot waste fluid is recovered only in the form of usable electricity. The waste fluid cooled by the heat exchanger is not further utilized in the current process. A drawback of the current process is that the cooled waste fluid is not further utilized.

[0008] Therefore, the problem to be solved is to provide a waste heat recovery system for generating steam in chemical industrial facilities, wherein waste heat taken from cooling intermittently operating reactors is also used to generate steam, and it is possible to continue generating steam even if reactor operation is interrupted. Another problem to be solved is to operate the waste heat recovery system efficiently and stably.

[0009] According to the present invention, these problems are solved by the waste heat recovery system according to claim 1 and the method for operating the waste heat recovery system according to claim 5. Advantageous embodiments of the waste heat recovery system of the present invention are given in claims 2 to 4. Furthermore, advantageous embodiments of the method for operating the waste heat recovery system of the present invention are given in claims 6 to 15.

[0010] The waste heat recovery system of the present invention for generating steam for a chemical industrial facility comprises: a non-continuously operating chemical industrial facility having at least one coolable reactor connected to a primary loop, wherein the at least one reactor is designed such that during operation of the reactor, a reaction mixture occurs, and waste heat generated by cooling of the reactor flows through the primary loop as a first heat transfer fluid in the form of a heated liquid or in the form of the reaction mixture itself, wherein the primary loop fluidly connects the reactor to a first heat exchanger in such a way that the first heat transfer fluid is cooled in the first heat exchanger and then returned to the reactor to cool the reactor.

[0011] A secondary loop, comprising a separate second heat transfer fluid and thermally coupled to a first heat exchanger, is provided such that during operation of at least one reactor, the second heat transfer fluid is heated by the first heat transfer fluid.

[0012] The secondary loop begins with the first heat exchanger and fluidly connects the first downstream heat storage unit, the evaporator unit downstream of the first heat storage unit, the second heat storage unit downstream of the evaporator unit, and the first heat exchanger downstream of the second heat storage unit to each other, thus completing the secondary loop.

[0013] The evaporator unit is designed such that steam is generated during the operation of the waste heat recovery system and preferably supplied to at least one compressor. Preferably, the compressed steam is then fed into an industrial facility and / or a steam network.

[0014] The waste heat recovery system of this invention has the following advantages: the waste heat obtained for cooling at least one discontinuously operating reactor enables continuous generation of industrial steam. Therefore, even in the event of reactor operation interruption, continuous generation of industrial steam will continue. The secondary loop with two heat storage units ensures efficient and stable operation of both at least one reactor and continuous industrial steam generation.

[0015] In this document, "coolable reactor" means a reactor in which the heat of reaction can be removed, for example, by circulation where a heat exchanger is present or by circulation of the reaction mixture through a heat exchanger outside the reactor, and / or by at least one cooling element in or on the reactor. In this case, the cooling element is preferably a heat exchanger inside the reactor, which takes the form, for example, a cooling coil, or a cooling spiral, tube bundle, or plate heat exchanger present in and / or on the outer wall of the reactor.

[0016] In this document, "heat exchanger" means a device that can transfer heat from one fluid to another. For example, a plate heat exchanger or a shell-and-tube heat exchanger can be used.

[0017] In this document, a "primary loop" is a circulation path in which the reactor is fluidly connected to a first heat exchanger, such that the first heat transfer fluid is cooled in the first heat exchanger and then returned to the reactor to cool the reactor. The primary loop may also include branches, for example, in the form of bypasses parallel to the reactor. Multiple reactors may also be arranged in the primary loop, for example, in parallel interconnection, series interconnection, or a combination of parallel and series interconnection.

[0018] In this document, the “secondary loop” is a circulation path in which a first heat exchanger is connected to the secondary loop such that during the operation of at least one reactor, a second heat transfer fluid is heated by the first heat transfer fluid, and the secondary loop fluidly connects downstream of the first heat exchanger to a first heat storage unit, an evaporator unit downstream of the first heat storage unit, a second heat storage unit downstream of the evaporator unit, and a first heat exchanger downstream of the second heat storage unit, thus completing the secondary loop.

[0019] If no reactor is available to operate, a second heat transfer fluid is also supplied from the first heat storage unit to the second heat storage unit, which allows for further operation of the evaporator unit and thus allows for continuous steam generation. In this case, the mass flow of the second heat transfer fluid from the second heat storage unit to the first heat storage unit is blocked.

[0020] If the existing reactor requires more cooling power, the cooler can be positioned between the second heat storage unit and the first heat exchanger to cool the second heat transfer fluid.

[0021] The secondary circuit may also include branches, such as bypasses parallel to the evaporator units. Multiple evaporator units may also be arranged in the secondary circuit, for example, in parallel interconnection, series interconnection, or a combination of parallel and series interconnection.

[0022] In this document, "evaporator unit" refers to a heat exchanger unit or flash tank unit. If the evaporator is a heat exchanger unit, the heat exchanger of the heat exchanger unit transfers heat flow from its primary side to its secondary side, which, for example, causes the water supplied to the secondary side to evaporate at least partially. In the case where the heat pump loop is connected to the secondary side, the operating medium in the heat pump loop evaporates accordingly.

[0023] An evaporator unit may also include additional standard components such as control valves, pressure regulators, closed-loop flow controllers, or sensors. Therefore, an evaporator unit may also include a closed-loop control system. The term "evaporator unit" can also generally be understood to refer to two or more evaporators connected in series or parallel.

[0024] Examples of suitable heat exchangers for evaporators include thin-film evaporators, Robert evaporators, falling-film evaporators, natural circulation evaporators, and forced circulation evaporators. These evaporators can be designed as shell-and-tube heat exchangers or plate heat exchangers. Suitable evaporators are known to those skilled in the art and are described in particular in the following: SPX, Evaporator Handbook, APV Americas, Engineered Systems, Separation Technologies, 4th Edition, available in […]. https: / / userpages.umbc.edu / ~dfrey1 / ench445 / Obtain apv_evap.pdf (Accessed May 20, 2022).

[0025] The term "flash tank unit" in this document refers to one possible form of evaporator unit. A flash tank unit has a tank, which preferably includes expansion nozzles in its upper region. If expansion nozzles are present, fluid is fed into the flash tank through the inlet of the expansion nozzles. If expansion nozzles should not be present, fluid is fed into the flash tank through a flash tank feed, which preferably leads to the flash tank. Unevaporated fluid accumulates in the lower region of the flash tank and is discharged through the flash tank outlet. Evaporated fluid is discharged through a steam outlet at the top of the flash tank.

[0026] In this document, "compressor" refers to a machine that compresses gases. A suitable example of a compressor is a geared turbo compressor. The latter is typically designed with multiple compression stages and intermediate stages, with the corresponding intermediate stages equipped with devices for intercooling.

[0027] In this document, "batch reactor" refers to a device that cannot be operated continuously, preferably a stirred tank. A batch reactor may be supplied with reactants only at the start of the process or also during the process. The first case is a purely batch process, while the second case is a semi-batch process.

[0028] In this document, the "batch reactor" can be operated using batch or semi-batch methods. The heat of reaction can be removed from the batch reactor through circulation, heat transfer, and recirculation of the reaction mixture and / or through at least one cooling element in or on the batch reactor. In this case, the cooling element is preferably a heat exchanger that can be located inside or outside the batch reactor. Such a heat exchanger can be, for example, at least one tube bundle or at least one plate heat exchanger. The cooling element can also take the form of cooling coils or cooling spirals present in and / or on the outer wall of the reactor.

[0029] In this document, "reaction of the reaction mixture" refers to a chemical reaction in a reactor. The reaction mixture comprises the supplied reactants and at least some of the components formed in the reaction, wherein the reaction mixture is present at the bottom of the reactor. For simplification, even in batch or semi-batch processes, the reactants supplied to the reactor can be considered as the reaction mixture, even when the reaction occurs only in the next step.

[0030] The reaction can be an exothermic reaction that generates heat in the reaction mixture and is at least partially used for steam generation. Other reactions can also occur, such as endothermic reactions. In the case of an endothermic reaction, the heat gained during reactor recooling is then at least partially used as waste heat for steam generation.

[0031] In this document, a "thermal storage unit" includes a thermal energy storage device that serves as a thermal energy storage apparatus, the outer wall of which may be insulated. The thermal storage apparatus has an inlet in the upper region of the tank, preferably in the uppermost part, and an outlet in the lower region, preferably in the lowermost part of the tank. The thermal storage unit may also include other standard components, such as control valves, pressure regulators, fill level sensors, closed-loop flow controllers, or sensors.

[0032] The heating element for thermal storage can also be located inside or on the outer wall of the thermal storage device to heat the fluid in the tank when the temperature is too low. Therefore, the thermal storage unit can also include a closed-loop control system. Generally, the term "thermal storage unit" can also refer to two or more thermal storage devices connected in series or parallel.

[0033] Thermal storage devices are typically capable of absorbing and storing fluids.

[0034] Preferably, the fluid is a liquid, such as water, hot oil, or a salt melt. The fluid may also be a gas, such as air or CO2.

[0035] In addition, thermal storage devices can also typically be thermal storage devices containing phase change materials, absorption storage devices, or adsorption storage devices, wherein adsorption storage devices contain adsorbents such as zeolite, activated carbon, or MOF.

[0036] Preferably, the phase change material is selected from the following list: fatty acid esters, glycols, sugar alcohols (e.g., xylitol or sorbitol), hydrates, or metals.

[0037] The "closed-loop temperature controller" in this document refers to a closed-loop controller that records the temperature at its installation location using a temperature sensor assigned to it. It is typically a PID controller.

[0038] The "closed-loop flow controller" in this document refers to a closed-loop controller that records flow rate at its installation location via a flow sensor assigned to it. It is typically a PID controller.

[0039] The “closed-loop load controller” in this document is a controller that determines the load using at least flow and temperature sensors, where the load corresponds to the transferred heat flow, i.e., the energy transferred per unit time, where the transferred heat flow is formed by the following product: the mass flow rate of the heat transfer fluid. The heat capacity C of the heat transfer fluid p (Temperature of the heat transfer fluid before heat transfer minus the temperature of the heat transfer fluid after heat transfer). Heat capacity C of the heat transfer fluid. p Preferably, it is considered a constant through simplification, and in this preferred case, it cannot be determined solely by sensors or by mathematical models.

[0040] In principle, the heat capacity C of the heat transfer fluid p It can also be expressed as a function of temperature, for example, as a function of the average value between the inlet and outlet temperatures of the heat exchanger. Typically, the closed-loop load controller is a PID controller.

[0041] The term "fluidly connected" in this document means that two or more flow-guiding components (such as multiple flow tubes, for example) are connected to each other in a manner that allows fluid to flow through these connected components. Typically, there should be a sufficient degree of technical impermeability when fluid flows through them.

[0042] The term "thermal connection" in this document means that two or more flow-conducting components (such as multiple flow tubes in a heat exchanger, for example) are connected to each other in such a way that one or more heat flows can be generated between the components.

[0043] In this document, "liquid" means a single-phase or multiphase fluid. Therefore, a liquid is free-flowing and transportable through the primary loop. A liquid may also include gaseous and / or solid components, provided that the liquid remains transportable.

[0044] In this document, "heat transfer fluid" means a single-phase or multiphase fluid, such as a liquid, gas, steam, or a mixture thereof. Therefore, heat transfer fluids are free-flowing. Heat transfer fluids may also include solid components, provided that the heat transfer fluid remains transportable. For example, heat transfer fluids may be heating steam, air, demineralized water, filtered river water, or a reaction mixture from a reactor.

[0045] The first heat transfer fluid can correspond to either the reaction mixture from the reactor or another fluid. In this document, the reaction mixture from the reactor is also referred to as the product stream.

[0046] The first heat transfer fluid used is preferably the following fluid:

[0047] Water, demineralized water, reaction mixture from the reactor, heat transfer oil (e.g., Therminol VP1, Xceltherm 600, Syltherm XLT, Dowtherm A, Calorie HAT 43, or Marlotherm SH), sunflower oil, organic liquids (e.g., ethanol, propane, butane, isobutanol, isoamyl alcohol, or octane), ammonia, mineral oil (e.g., engine oil or Mobilstherm 605), inorganic molten salts, liquid metals (e.g., sodium, lead, bismuth, potassium, and their alloys).

[0048] The second heat transfer fluid used is preferably the following fluid:

[0049] Water, demineralized water, heat transfer oils (e.g., Therminol VP1, Xceltherm 600, Syltherm XLT, Dowtherm A, Calorie HAT 43, or Marlotherm SH), sunflower oil, organic liquids (e.g., ethanol, propane, butane, isobutanol, isoamyl alcohol, or octane), ammonia, mineral oils (e.g., engine oil or Mobilstherm 605), inorganic molten salts, and liquid metals (e.g., sodium, lead, bismuth, potassium, and their alloys).

[0050] The term "cold fluid" in this document means that the fluid in the stratified storage device will not drop below a predetermined minimum temperature, and the temperature of the fluid is only above the minimum temperature by a maximum of half the difference between the predetermined maximum temperature of the fluid in the stratified storage device and the predetermined minimum temperature of the fluid in the stratified storage device.

[0051] The term “warm fluid” in this document means that the corresponding fluid in the stratified storage device will not exceed a predetermined maximum temperature, and the temperature of the fluid is only lower than the maximum temperature by a maximum of half the difference between the predetermined maximum temperature of the fluid in the stratified storage device and the predetermined minimum temperature of the fluid in the stratified storage device.

[0052] In a preferred embodiment of the waste heat recovery system of the present invention, at least one reactor is a batch reactor. Preferably, the exothermic reaction occurs in the reactor.

[0053] The benefit of this is that steam can still be generated during periods when the batch reactor is not operating and has cooled down. Therefore, the heat released in the exothermic reaction is used efficiently for steam generation.

[0054] In a preferred embodiment of the waste heat recovery system of the present invention, at least one reactor has at least one cooling element, which preferably includes at least one integrated cooling coil, an integrated tube bundle and / or a heat exchanger outside or inside at least one reactor, and wherein at least one cooling element is fluidly connected to the primary loop and is configured such that during operation of the industrial facility, a first heat transfer fluid passes through at least one cooling element.

[0055] The benefit of this is that heat can be efficiently removed from the reactor so that it can be used to generate steam.

[0056] In a preferred embodiment of the waste heat recovery system of the present invention, the second heat transfer fluid is water, preferably demineralized water, and the first heat transfer fluid is also water, preferably demineralized water.

[0057] The benefit of this is that the flash tank unit can be used as an evaporator unit, and the reaction mixture does not have to be transported out of the reactor and then returned to cool the reactor.

[0058] In a preferred embodiment of the waste heat recovery system of the present invention, the second heat transfer fluid is water, preferably demineralized water, and the first heat transfer fluid is a reaction mixture.

[0059] The benefit of this is that the flash tank unit can be used as an evaporator unit, and no additional heat exchanger is required to cool the reactor.

[0060] In a preferred embodiment of the waste heat recovery system of the present invention, the second heat transfer fluid is water, and the evaporator unit is a flash tank unit having an inlet for filling the flash tank with the second heat transfer fluid, an inlet for filling the flash tank with water, preferably demineralized water, an outlet for discharging water to a second heat storage unit, a steam outlet, and an expansion nozzle designed such that, during operation of the waste heat recovery system, expanded steam is generated as steam, and the steam is supplied to at least one compressor through the steam outlet.

[0061] In a preferred embodiment of the waste heat recovery system of the present invention, the evaporator unit is a heat exchanger unit having an inlet and an outlet for a second heat transfer fluid to pass through, an inlet for water to pass through, and a steam outlet, wherein the heat exchanger unit is designed such that during operation of the waste heat recovery system, water in the heat exchanger unit evaporates and is fed to at least one compressor through the steam outlet.

[0062] The benefit of this is that, compared to the flash tank unit, a fluid different from water can be used as the second heat transfer fluid.

[0063] In a preferred embodiment of the waste heat recovery system of the present invention, there is more than one reactor, and the reactors are interconnected in parallel with each other, and each reactor has its own heat exchanger, wherein each heat exchanger is thermally connected to a secondary loop.

[0064] The benefit of this is that the reactor does not become too large at greater production capacity, and the reactor can operate at different operating times, which correspondingly shortens the time intervals during which no reactor generates waste heat.

[0065] In a preferred embodiment of the waste heat recovery system of the present invention, a vertical stratified storage device replaces the first heat storage unit and the second heat storage unit, wherein the inlet for the second heat transfer fluid originating from the first heat exchanger is in the upper region of the stratified storage device, preferably at the top, and wherein the inlet for the second heat transfer fluid originating from the evaporator unit is in the lower region of the stratified storage device.

[0066] The stratified storage device here has an outlet to the first heat exchanger, which is preferably located in the lower region of the stratified storage device, more preferably at the bottom. Additionally, the stratified storage device has an outlet to the evaporator unit, which is preferably located in the upper region of the stratified storage device.

[0067] In this document, "at the top" means the highest point in the tiered storage device. "At the bottom" means the lowest point in the tiered storage device. "In the upper region" means a point in the tiered storage device at a height ranging from 75% to 100% of the maximum height of the tiered storage device. "In the lower region" means a point in the tiered storage device at a height ranging from 0% to 25% of the maximum height of the tiered storage device.

[0068] In a preferred embodiment of the waste heat recovery system, the evaporator unit is a heat exchanger. A closed heat pump loop is also fluidly connected to the secondary side of this heat exchanger, and this closed heat pump loop includes a compressor, a Joule-Thomson valve or turbine, and additional heat exchangers. The turbine may also generate mechanical or electrical energy. The operating medium for the closed heat pump loop can be, for example, water and / or synthetic fluids. Organic fluids, such as pentane or heptane, are also generally suitable as the operating medium for the closed heat pump loop. Preferably, a hydrocarbon fluid is used as the operating medium for the closed heat pump loop. More preferably, ammonia is used as the operating medium for the closed heat pump loop.

[0069] An additional heat exchanger in a closed heat pump loop causes water supplied to its secondary side to evaporate, producing industrial steam. For example, industrial steam with an absolute pressure ranging from 1.5 bar to 2.0 bar can thus be generated. Any downstream compressor can then increase the steam pressure and temperature.

[0070] The present invention further provides a method for operating a waste heat recovery system.

[0071] The method of the present invention for operating a waste heat recovery system for generating steam for chemical industrial facilities includes:

[0072] • A non-continuously operating chemical industrial facility having at least one coolable reactor, wherein the reactor is designed such that during operation of the reactor, a reaction mixture undergoes a reaction, and waste heat generated by the cooling of the reactor flows through a primary loop as a first heat transfer fluid, either in the form of a heated liquid or in the form of the reaction mixture itself. The primary loop fluidly connects the reactor to a first heat exchanger in such a manner that the first heat transfer fluid is cooled in the first heat exchanger and then returned to the reactor to cool the reactor.

[0073] • A secondary loop comprising a separate second heat transfer fluid and thermally coupled to a first heat exchanger, wherein the second heat transfer fluid is heated by the first heat transfer fluid during operation of at least one reactor.

[0074] The secondary loop begins with the first heat exchanger and fluidly connects the first downstream heat storage unit, the evaporator unit downstream of the first heat storage unit, the second heat storage unit downstream of the evaporator unit, and the first heat exchanger downstream of the second heat storage unit to each other, thus completing the secondary loop.

[0075] The method of the present invention includes the following steps when at least one reactor is running:

[0076] • The reactants are fed into at least one reactor.

[0077] • The reaction is carried out in at least one reactor.

[0078] At least one reactor is cooled by the first heat transfer fluid, which preferably flows through a first heat exchanger.

[0079] • A portion of the heat from the first heat transfer fluid is transferred to the second heat transfer fluid via the first heat exchanger, wherein...

[0080] The second heat transfer fluid at the inlet of the first heat exchanger has a temperature ranging from 10°C to 1450°C and an absolute pressure ranging from 0.1 bar to 400 bar, and the second heat transfer fluid at the outlet of the first heat exchanger has a temperature ranging from 30°C to 1500°C and an absolute pressure ranging from 0.1 bar to 400 bar.

[0081] Furthermore, the first heat transfer fluid at the inlet of the first heat exchanger has a temperature ranging from 35°C to 1500°C and an absolute pressure ranging from 0.1 bar to 400 bar, and the first heat transfer fluid at the outlet of the first heat exchanger has a temperature ranging from 30°C to 1500°C and an absolute pressure ranging from 0.1 bar to 400 bar.

[0082] • The heated second heat transfer fluid is fed into the first heat storage unit, wherein the second heat transfer fluid in the first heat storage unit is at a temperature ranging from 30°C to 1500°C and an absolute pressure ranging from 0.1 bar to 400 bar.

[0083] • A second heat transfer fluid is fed from the first heat storage unit to the evaporator unit, wherein the flow rate of the second heat transfer fluid is determined based on both the heat flow transferred by the evaporator unit and the fill level of the first heat storage unit, and is regulated by a first valve located between the first and second heat storage units along the main flow direction.

[0084] Furthermore, the temperature of the second heat transfer fluid at the inlet of the evaporator unit is in the range of 30°C to 1500°C, and the absolute pressure at the inlet of the evaporator unit is in the range of 0.1 bar to 400 bar.

[0085] Furthermore, the temperature of the second heat transfer fluid at the outlet of the evaporator unit is in the range of 10°C to 1450°C, and the absolute pressure at the outlet of the evaporator unit is in the range of 0.1 bar to 400 bar.

[0086] • Water is supplied to the evaporator unit via a feed p outside the secondary loop, wherein the water at the inlet of the evaporator unit is at a temperature ranging from 5°C to 400°C and an absolute pressure ranging from 0.001 bar to 300 bar.

[0087] • Steam is generated in the evaporator unit by heat supplied from the second heat transfer fluid, wherein the steam at the steam outlet of the evaporator unit is at a temperature ranging from 5°C to 373°C and an absolute pressure ranging from 0.001 bar to 220 bar.

[0088] • Steam from the steam outlet of the evaporator unit is fed to at least one compressor via a conduit outside the secondary circuit. This compressor compresses the steam to an absolute pressure in the range of 0.5 bar to 220 bar, and the steam temperature at the outlet of the at least one compressor is correspondingly in the range of 5°C to 373°C.

[0089] • A second heat transfer fluid is fed from the evaporator unit into the second heat storage unit, wherein the second heat transfer fluid within the second heat storage unit is at a temperature ranging from 10°C to 1450°C and an absolute pressure ranging from 0.1 bar to 400 bar.

[0090] • The second heat transfer fluid is fed from the second heat storage unit into the first heat exchanger.

[0091] The method of the present invention includes the following steps: when one reactor is not operating, or when none of the multiple reactors are operating.

[0092] • A second heat transfer fluid is fed from the first heat storage unit into the evaporator unit, wherein the flow rate of the second heat transfer fluid is determined based on both the heat flow transferred by the evaporator unit and the fill level of the first heat storage unit, and is regulated by a first valve located between the first and second heat storage units along the main flow direction. The temperature of the second heat transfer fluid at the inlet of the evaporator unit is in the range of 30°C to 1500°C, and the absolute pressure at the inlet of the evaporator unit is in the range of 0.1 bar to 400 bar.

[0093] • Water is supplied to the evaporator unit via an external feed line to the secondary loop, wherein the water at the inlet of the evaporator unit is at a temperature ranging from 5°C to 400°C and an absolute pressure ranging from 0.001 bar to 300 bar.

[0094] • Steam is generated in the evaporator unit by heat supplied from the second heat transfer fluid, wherein the steam at the outlet of the evaporator unit is at a temperature ranging from 5°C to 373°C and an absolute pressure ranging from 0.001 bar to 220 bar.

[0095] • Steam from the evaporator unit is fed into at least one compressor, which compresses the steam to an absolute pressure in the range of 0.5 bar to 373 bar, and the steam temperature at the outlet of the at least one compressor is correspondingly in the range of 80°C to 220°C.

[0096] • A second heat transfer fluid is fed from the evaporator unit into the second heat storage unit, wherein the second heat transfer fluid within the second heat storage unit is at a temperature ranging from 10°C to 1450°C and an absolute pressure ranging from 0.1 bar to 400 bar.

[0097] • The flow of the second heat transfer fluid between the second heat storage unit and the first heat storage unit in the main flow direction is blocked by cutting off the flow via a second valve located between the second heat storage unit and the first heat storage unit in the main flow direction.

[0098] The benefit of this method is that the waste heat obtained for cooling at least one discontinuously operating reactor allows for the continuous generation of industrial steam. Therefore, even in the event of reactor operation interruption, the continuous generation of industrial steam will continue. The secondary loop with two thermal storage units ensures efficient and stable operation of both at least one reactor and continuous industrial steam generation.

[0099] In a preferred embodiment of the method for operating a waste heat recovery system according to the present invention, the evaporator unit is a heat exchanger unit. At least one compressor is a mechanical steam compressor, and the water at the inlet of the evaporator unit is at a temperature ranging from 5°C to 400°C and an absolute pressure ranging from 0.001 bar to 300 bar. Additionally, steam is compressed by at least one compressor to an absolute pressure ranging from 0.5 bar to 220 bar, and the steam temperature at the outlet of at least one compressor is in the range of 80°C to 373°C.

[0100] The benefit of this is that, compared to the flash tank unit, a fluid different from water can be used as the second heat transfer fluid.

[0101] In a preferred embodiment of the method of the present invention for operating a waste heat recovery system, the evaporator unit is a flash tank unit. At least one compressor is a mechanical steam compressor, and the water at the inlet of the flash tank unit is at a temperature ranging from 5°C to 400°C and an absolute pressure ranging from 0.001 bar to 300 bar. Additionally, steam is compressed by at least one compressor to an absolute pressure ranging from 0.5 bar to 220 bar, and the temperature of the steam at the outlet of at least one compressor is correspondingly in the range of 80°C to 373°C.

[0102] The benefit of this is that there is almost no temperature drop (if any) compared to the heat exchanger, which is an evaporator unit, and therefore the steam generated by the flash tank unit is at a temperature 1°C to 10°C higher, preferably 4°C to 6°C higher.

[0103] In a preferred embodiment of the method for operating a waste heat recovery system according to the present invention, the temperature of the second heat transfer fluid at the inlet of the first heat storage unit is regulated by a first closed-loop temperature controller having an associated temperature sensor located between the second heat storage unit and the first heat storage unit along the main flow direction, in conjunction with a first closed-loop flow controller having an associated flow sensor, wherein the first closed-loop temperature controller determines the difference between a predetermined setpoint value and the temperature of the second heat transfer fluid at the inlet of the first heat storage unit detected by the first closed-loop temperature controller.

[0104] Furthermore, the first closed-loop temperature controller transmits the setpoint value to the first closed-loop flow controller based on the determined difference, and the first closed-loop flow controller adjusts the flow rate from the second thermal storage unit to the first thermal storage unit according to the setpoint value and the measured flow rate from the second thermal storage unit to the first thermal storage unit.

[0105] The benefit of this is that the temperature in the first thermal storage unit remains essentially the same, with only small temperature fluctuations (if any).

[0106] The predetermined setpoint value here generally corresponds to the desired temperature value of the first thermal storage unit.

[0107] In a preferred embodiment of the method of the present invention for operating a waste heat recovery system, the temperature of the second heat transfer fluid at the inlet of the second heat storage unit is regulated by a second closed-loop temperature controller having its associated temperature sensor, combined with a second closed-loop flow controller having its associated flow sensor in the feed of the evaporator unit.

[0108] Specifically, the second closed-loop temperature controller determines the difference between a predetermined setpoint value and the temperature of the second heat transfer fluid at the inlet of the second thermal storage unit, as detected by the second closed-loop temperature controller.

[0109] The second closed-loop temperature controller transmits the setpoint value to the second closed-loop flow controller based on the determined difference, and the second closed-loop flow controller adjusts the flow rate of the water to be evaporated in the conduit to the evaporator unit through a valve according to the setpoint value and the measured flow rate in the conduit to the evaporator unit.

[0110] The benefit of this is that the temperature in the second thermal storage unit remains essentially the same, with only small temperature fluctuations (if any).

[0111] In addition, this also regulates the mass flow rate of the water to be evaporated, as well as the temperature and pressure of the generated steam.

[0112] The predetermined setpoint value here generally corresponds to the desired temperature value of the second thermal storage unit.

[0113] In a preferred embodiment of the method of the present invention for operating a waste heat recovery system, the operating load of at least one compressor is adjusted to a value within the range of 30% to 100%, preferably 60% to 100%, of its maximum operating load, depending on the valve position.

[0114] The benefit of this is that the compressor can operate efficiently and stably.

[0115] In a preferred embodiment of the method of the present invention for operating a waste heat recovery system, a first closed-loop fill level controller of the first thermal storage unit, having its associated fill level sensor, serves as a higher-level closed-loop controller. If the fill level sensor detects a value exceeding the defined maximum fill level of the first thermal storage unit, a second primary loop valve closes and a first primary loop valve opens to cool the mass flow of the reaction mixture exiting the reactor in the process heat exchanger. In this case, the mass flow of the reaction mixture exiting the reactor is not directed through the first heat exchanger.

[0116] The benefit this provides is that even if the compressor has already generated maximum steam flow and the first thermal storage unit is essentially full and therefore has little more storage capacity (if any), at least one reactor can still be cooled.

[0117] In a preferred embodiment of the method of the present invention for operating a waste heat recovery system, a closed-loop load controller having its associated sensors is included.

[0118] This includes a flow sensor in a conduit downstream of the evaporator unit and / or in a conduit upstream of the evaporator unit, a temperature sensor in a conduit downstream of the evaporator unit, and a temperature sensor for detecting the temperature upstream of the evaporator unit.

[0119] The heat flow difference between the heat flow of the second heat transfer fluid in the duct downstream of the evaporator unit and the heat flow of the second heat transfer fluid in the duct upstream of the evaporator unit is calculated. The difference between the detected heat flow difference and a defined load setpoint is given as a setpoint value. This setpoint value is transmitted to a third closed-loop flow controller, which acts as a slave controller and has its associated flow sensor.

[0120] The difference between the flow rates of the second heat transfer fluid in the two ducts upstream and downstream of the evaporator unit, calculated by the third closed-loop flow controller, and the setpoint value determined by the closed-loop load controller, is used as the basis for the closed-loop control of the second-stage loop valve, which accordingly adjusts the flow rate of the second heat transfer fluid in the duct downstream of the evaporator unit.

[0121] The benefit of this is that the heat flow rate transferred by the second heat transfer fluid can be optimized based on a defined load setpoint.

[0122] In a preferred embodiment of the method of the present invention for operating a waste heat recovery system, a defined load setpoint is determined by a second closed-loop fill level controller having an associated fill level sensor within a first thermal storage unit, wherein the second closed-loop fill level controller is a master controller, preferably a P controller. The second closed-loop fill level controller calculates the difference between the fill level of the first thermal storage unit and the defined fill level setpoint, determines the load setpoint based on the difference, and transmits it to a closed-loop load controller.

[0123] The benefit of this is that the fill level of the first thermal storage unit serves as a defined load setpoint and thus affects the heat flow rate used for steam generation. If the fill level is low, the heat flow rate will be low so that the first thermal storage unit is not emptied. And if the fill level is high, the heat flow rate will be correspondingly higher so that the first thermal storage unit is not overfilled.

[0124] In a preferred embodiment of the method of the present invention for operating a waste heat recovery system, a second closed-loop fill level controller detects continuous fill level values ​​in the first thermal storage unit. The load setpoint of the closed-loop load controller is determined based on the detected fill level values, wherein the detected fill level values ​​are limited to a range from a defined minimum fill level value to a defined maximum fill level value.

[0125] The advantage of this embodiment is that it is easier to implement in a process control system. The disadvantage is that the setpoint for the heat flow difference can be any value between the "maximum steam production" mode and the "minimum steam production" mode. Therefore, this is a continuous closed-loop control operation.

[0126] In a preferred embodiment of the method of the present invention for operating a waste heat recovery system, the defined load setpoint is determined by a fill level sensor, wherein the load setpoint may take only discrete values. Preferably, switching can only occur between a first value corresponding to minimum steam production and a second value corresponding to maximum steam production.

[0127] The advantage of this embodiment is that the closed-loop load controller UC operates essentially either in "minimum steam production" mode or "maximum steam production" mode, and not in between. Therefore, this is a discontinuous closed-loop control operation.

[0128] This discontinuous closed-loop control operation is advantageous for the compressor because it does not need to constantly change its operating mode.

[0129] In a preferred embodiment of the method of the present invention for operating a waste heat recovery system, at least one reactor is a batch reactor.

[0130] The benefit of this is that the heat recovery system can operate efficiently because the downtime of the batch reactor allows for optimal use of the heat storage unit.

[0131] In a preferred embodiment of the method of the present invention for operating a waste heat recovery system, at least one reactor has at least one cooling element, which preferably includes at least one integrated cooling coil, tube bundle and / or plate heat exchanger, and wherein at least one cooling element is fluidly connected to a primary loop and is configured such that during operation of the industrial facility, a first heat transfer fluid passes through at least one cooling element.

[0132] The benefit of this is that even if the first thermal storage unit is full and the compressor has reached its capacity limit and therefore cannot produce any greater mass flow of compressed steam, at least one reactor is still cooled.

[0133] In a preferred embodiment of the method for operating a waste heat recovery system according to the present invention, a first heat storage unit and a second heat storage unit are combined to form a vertically layered storage device (e.g., as shown in the figure). Figure 5 As shown), the inlet for the second heat transfer fluid originating from the first heat exchanger is in the upper region of the stratified storage device, preferably at the top of the stratified storage device, and the inlet for the second heat transfer fluid originating from the evaporator unit is in the lower region of the stratified storage device, preferably at the bottom of the stratified storage device.

[0134] The advantage of this is that only one jar is required instead of two.

[0135] The preferred closed-loop control concept when using a stratified storage device depends on the discrete switching of the temperature distribution of the liquid in the stratified storage device.

[0136] In a preferred embodiment, the closed-loop control system includes components arranged according to... Figure 5 At least four temperature sensors at the height of the tiered storage device.

[0137] Based on the temperatures measured at these locations, there should be discrete switching between "no recovery" and "minimum recovery" states, and between "minimum recovery" and "maximum recovery" states. The compressor that compresses the steam generated by the evaporator unit operates according to the following discrete states: "no recovery," "minimum recovery," and "maximum recovery." For example, when the value is "maximum recovery," the compressor operates at maximum load. If the value is "no recovery," the compressor is shut down. If the value is "minimum recovery," the compressor operates at a load ranging from 30% to 90% of full load, preferably from 60% to 80%. This discrete closed-loop control logic also serves as the basis for determining the setpoint value of the closed-loop controller UC.

[0138] For example, discrete states can be determined as follows:

[0139] according to Figure 5 Temperature sensors T1, T2, T5, and T6 are arranged from top to bottom in the layered storage device at the height of the layered storage device.

[0140] At the start of the process, the stratified storage device is filled with cold fluid, and the discrete state is set to "no recovery". When the temperature of temperature sensor T2 exceeds a predetermined value T... 热 At this time, the discrete state is set to "minimum recovery". When the temperature of temperature sensor T1 drops below a predetermined value T from the "minimum recovery" state... 冷 The discrete state is changed from "minimum recycling" to "no recycling".

[0141] When the temperature of temperature sensor T6 exceeds the predetermined value T when starting from the "minimum recovery" state... 热 At that time, the status is set to "maximum recycling".

[0142] When the temperature of temperature sensor T5 is lower than the predetermined value T when starting from the "maximum recovery" state. 冷 At that time, the status is set to "minimum recycling".

[0143] These switching mechanisms typically begin immediately upon meeting the conditions. However, they occur over a period of time to avoid large, immediate changes in compressor load. Therefore, the transition from "minimum recovery" to "maximum recovery" should occur within a predetermined time period (e.g., 5 minutes).

[0144] In a preferred embodiment, when using a tiered storage device, the closed-loop control system includes an additional closed-loop controller QC to protect the waste heat recovery system from overload. Preferably, this additional closed-loop controller QC replaces the closed-loop fill level controller LC used for variants with two heat storage units.

[0145] This additional closed-loop controller (QC) can, for example, act as a soft sensor using the distribution of liquid density and / or liquid temperature along the height of the tiered storage unit to determine scalar values ​​as actual values. Then, based on... Figure 5 The difference between the actual value and the predetermined setpoint value can be used to set the valve in the feed of the first heat exchanger and the valve in the feed of the process heat exchanger.

[0146] Typically, alternative closed-loop controllers (QC) and density can also control different physical characteristics, wherein the physical characteristics preferably depend on temperature. Here, the closed-loop control is preferably based on a scalar value, which is preferably determined by a soft sensor. The soft sensor may take temperature and / or other measurements into account when determining the scalar value.

[0147] Density can be determined using various measurement techniques, such as capacitance measurement, which measure the average density in a layered storage device by mounting electrodes at the height of the device, preferably based on a volume-based average. In principle, density measurement based on ultrasonic testing methods is also suitable, for example.

[0148] In a preferred embodiment, the density determined at the height of the tiered storage device is used as the basis for calculating the amount of cold and hot fluid in the tiered storage device.

[0149] When the fluid density over the entire height of the tiered storage device substantially corresponds to the maximum permissible temperature of the fluid, and thus the entire volume of the tiered storage device is substantially filled with hot fluid, it means that the tiered storage device has reached its maximum storage capacity.

[0150] In this case, density thus indirectly indicates the amount of hot fluid in the stratified storage unit. Additionally, density indicates the extent to which the maximum storage capacity of the stratified storage unit has been reached and the amount of steam that the heat recovery system can generate.

[0151] When the maximum storage capacity of the stratified storage unit has been reached, the compressor preferably operates at "maximum recovery". In this case, preferably, less of the first heat transfer fluid passes through the first heat exchanger. Therefore, if the average density of the stratified storage unit across its volume is below a predetermined setpoint, an additional closed-loop controller (preferably a PID controller) preferably reduces the heat flow from the reactor to the stratified storage unit, specifically according to... Figure 5The valve in the feed of the first heat exchanger is opened to a smaller extent, while the valve in the feed of the process heat exchanger is opened to a larger extent.

[0152] In a preferred embodiment of the method of the present invention for operating a waste heat recovery system, the first heat transfer fluid is water, preferably demineralized water, and the second heat transfer fluid is water, preferably demineralized water.

[0153] The benefit of this is that the flash tank unit can be used as an evaporator unit, and the reaction mixture does not have to be transported out of the reactor and then returned to cool the reactor.

[0154] In a preferred embodiment of the method of the present invention for operating a waste heat recovery system, the second heat transfer fluid is water, preferably demineralized water, and the first heat transfer fluid is a reaction mixture.

[0155] The benefit of this is that the flash tank unit can be used as an evaporator unit, and no additional heat exchanger is required to cool the reactor.

[0156] In a preferred embodiment of the method of the present invention for operating a waste heat recovery system, there is more than one reactor, and the reactors are connected in parallel with each other. Each reactor has its own heat exchanger, wherein each heat exchanger is thermally connected to a secondary loop.

[0157] The benefit of this is that the reactor does not become too large at greater production capacity, and the reactor can operate at different operating times, which correspondingly shortens the time intervals during which no reactor generates waste heat.

[0158] In a preferred embodiment of the method of the present invention for operating a waste heat recovery system, the steam compressed in the compressor is used for the industrial facility itself, which cannot be operated continuously, and / or for other industrial facilities.

[0159] The advantage of this is that steam can be allocated according to the required amount. For example, if an industrial facility itself requires less steam than it produces, the produced steam can be used for another industrial facility.

[0160] The invention is illustrated in detail below with reference to the accompanying drawings. The drawings should be considered schematic diagrams. They do not limit the invention, for example, regarding specific dimensions or design variations. The drawings show:

[0161] Figure 1 A waste heat recovery system for generating industrial steam, comprising a secondary loop in which a heat exchanger unit for steam generation is located between a first heat storage unit and a second heat storage unit. Additionally, Figure 1 A process flow diagram of the waste heat recovery system is also shown.

[0162] Figure 2A waste heat recovery system for generating industrial steam, comprising a secondary loop in which a flash tank unit for steam generation is located between a first heat storage unit and a second heat storage unit. Additionally, Figure 2 A process flow diagram of the waste heat recovery system is also shown.

[0163] Figure 3 Simulation results of the heat recovery system based on Example 1, which has been running for 20 days.

[0164] Figure 4 Simulation results of the heat recovery system based on Example 2, which has been running for 20 days.

[0165] Figure 5 A waste heat recovery system for generating industrial steam, which uses a stratified storage unit instead of two separate storage units. Additionally, Figure 5 A process flow diagram of the waste heat recovery system is also shown.

[0166] Figure 6 A waste heat recovery system for generating industrial steam, wherein a heat pump circuit connected to the evaporator unit is attached to the waste heat recovery system.

[0167] List of reference numerals used in the figures:

[0168] 1. A mixer for mixing two reactant mass streams, a and b.

[0169] 2. Batch reactors for the alkoxylation of propylene oxide a and ethylene oxide b

[0170] 4 Primary Circulation Pump

[0171] 5. Valve for regulating the mass flow of the reaction mixture in conduit e

[0172] 6. First primary loop valve for regulating mass flow f

[0173] 7. Process heat exchanger for temperature control of the reaction mixture added to mixer 1 via conduit i.

[0174] 8. Second primary loop valve for regulating mass flow j

[0175] 9. First heat exchanger used to heat the incoming mass flow l via mass flow j.

[0176] 10 has a first closed-loop filling level controller, a second closed-loop filling level controller, and a temperature sensor T1, serving as an insulated tank for the first thermal storage unit 10.

[0177] 11 is the primary circulation pump used to empty the insulated tank 10 or the stratified storage device 20.

[0178] 12. Valve used to regulate mass flow o

[0179] 13 Evaporator Units

[0180] 14 is a cold tank equipped with a temperature sensor T2, serving as the second thermal storage unit 14.

[0181] 15 is the second-stage circulation pump used to empty the cold tank 14.

[0182] 16 Valve for regulating the mass flow l through heat exchanger 9

[0183] 17 Valve for regulating the mass flow p entering evaporator unit 13

[0184] 18 Compressor for mechanical vapor compression via mass flow q

[0185] 19. Secondary circulation pump for filling cold tank 14

[0186] 20-layer storage device

[0187] propylene oxide reactant mass flow

[0188] b. Reactant mass flow of ethylene oxide

[0189] c. Optional additional reactant mass flow

[0190] d Product stream from the mass stream of the reaction mixture in batch reactor 2

[0191] e. The mass flow of the reaction mixture from the effluent of the system or process.

[0192] f is the mass flow feed of the reaction mixture entering heat exchanger 7.

[0193] Water mass flow is fed into heat exchanger 7 to cool or heat the reaction mixture mass flow from feed f and feed k.

[0194] h is the conduit used to discharge the water mass flow from heat exchanger 7.

[0195] i. Mass flow of reaction mixture from heat exchanger 7 to mixer 1 is fed into the mixer.

[0196] k is used to add the mass flow of the reaction mixture from heat exchanger 9 to the feed f.

[0197] The mass flow of the second heat transfer fluid is fed from the second heat storage unit 14 to the heat exchanger 9.

[0198] The mass flow of the second heat transfer fluid is fed from the heat exchanger 9 to the first heat storage unit 10.

[0199] The mass flow of the second heat transfer fluid is fed from the first heat storage unit 10 to the evaporator unit 13.

[0200] The mass flow of the second heat transfer fluid is fed from heat exchanger unit 13 to the second heat storage unit 14.

[0201] The conduit through which p-water flows to evaporator unit 13 to generate steam.

[0202] The q-vapor mass flow is fed from the evaporator unit 13 to the compressor 18 for vapor compression.

[0203] Compressed steam is discharged from the mass flow effluent of the system or process.

[0204] s is used for desalination of water for evaporation

[0205] FC is a closed-loop flow controller with corresponding flow sensors F1, F2, and F3.

[0206] L1_1 First Fill Level Sensor

[0207] L1_2 Second Fill Level Sensor

[0208] LC is used for the first closed-loop fill level controller and the second closed-loop fill level controller of the first thermal storage unit 10.

[0209] Another closed-loop controller for QC

[0210] TC has a closed-loop temperature controller with corresponding temperature sensors T1, T2, T3 and T4.

[0211] UC has a load controller for its associated temperature and flow sensors, represented by U1.

[0212] Figure 1 A process flow diagram and schematic diagram of the industrial process of the waste heat recovery system according to a first embodiment of the waste heat recovery system and the method of the present invention are shown.

[0213] A first embodiment of the invention for a waste heat recovery system for generating steam for chemical industrial facilities includes a coolable batch reactor 2 connected to the primary loop, wherein the batch reactor 2 is designed such that an exothermic reaction of the reaction mixture occurs during operation of the batch reactor 2. In this case, two reactant mass streams a and b are mixed through a mixer 1 and then fed into the batch reactor 2. Optionally, an additional reactant stream c can be fed into the batch reactor through a separate feed and a separate inlet.

[0214] To cool the batch reactor 2 driven by the primary circulation pump 4, the reaction mixture itself flows as the first heat transfer fluid through the primary loop, which fluidly connects the batch reactor 2 to the first heat exchanger 9 via conduits d and j, such that the first heat transfer fluid is cooled in the first heat exchanger 9 and then returned to the mixer 1 via conduit i to cool the batch reactor 2. The flow rate of the reaction mixture leaving the system can be adjusted by valve 5.

[0215] The first primary loop valve 6 is used for closed-loop control of the mass flow of the first heat transfer fluid at the inlet of the feed f of the process heat exchanger 7, wherein the closed-loop control is based on a first closed-loop fill level controller of the first heat storage unit 10 with an associated fill level sensor L1_1. The closed-loop control system preferably calculates the difference between the currently measured fill level and a predetermined value. This difference is then used as the basis for setting the first primary loop valve 6.

[0216] The goal is to recover as much heat of reaction as possible. This means that primary loop valve 6 should generally be closed first, and second primary loop valve 8 in feed j should generally be opened first, wherein second primary loop valve 8 is generally used to control the mass flow of the first heat transfer fluid to the first heat exchanger 9.

[0217] However, if the compressor 18 is already operating at maximum power and the fill level of the first heat storage unit 10 exceeds a predetermined value, the first closed-loop fill level controller with its associated fill level sensor L1_1 throttles the valve 8 and opens the valve 6, so that at least a portion of the product stream d is cooled in the process heat exchanger 7 and does not flow through the first heat exchanger 9.

[0218] The process heat exchanger 7 can control the temperature of the first heat transfer fluid from feed f and feed k. The temperature-controlled first heat transfer fluid is then added to the mixer 1 through conduit i. The cooling or heating medium for the process heat exchanger 7 is fed into the process heat exchanger 7 through feed g and withdrawn from the process heat exchanger 7 through conduit h.

[0219] When the heat recovery system is running, process heat exchanger 7 is typically in standby mode. In this case, process heat exchanger 7 does not cool the first heat transfer fluid, even though the first heat transfer fluid continues to flow through the process heat exchanger. Instead, cooling of the first heat transfer fluid occurs in the first heat exchanger 9.

[0220] Process heat exchanger 7 preferably undertakes the task of cooling at least part of the product flow d only when the heat flow cannot be recovered by the heat recovery system.

[0221] The mass flow of the first heat transfer fluid is cooled by the first heat exchanger 9 and added to the mass flow of the first heat transfer fluid in the conduit f through the conduit k.

[0222] A separate secondary loop includes a second heat transfer fluid and is connected to the first heat exchanger 9 in such a way that the second heat transfer fluid is heated by the first heat transfer fluid during operation of the batch reactor 2. Specifically, the second heat transfer fluid flows into the first heat exchanger 9 through conduit l, where it is heated by the first heat transfer fluid on the primary loop side of the first heat exchanger 9, and is then fed into the first thermal storage unit 10 through feed m.

[0223] The secondary loop begins at the first heat exchanger 9 and is fluidly connected to the downstream first heat storage unit 10 via feed m, fluidly connected to the downstream heat exchanger unit 13 via conduit n, fluidly connected to the downstream second heat storage unit 14 via conduit o, and fluidly connected to the downstream first heat exchanger 9 via conduit l, thus completing the secondary loop. The first-stage circulation pump 11 transports the second heat transfer fluid from the first heat storage unit to the heat exchanger unit 13 via conduit n. The second-stage circulation pump 15 transports the second heat transfer fluid from the second heat storage unit 14 to the first heat exchanger 9 via conduit l.

[0224] The primary loop valve 16 is used to control the mass flow in the feed l of the first heat exchanger 9, wherein the closed-loop control is performed based on a first closed-loop temperature controller, which is the master controller and has its associated temperature sensor T3 that detects the temperature of the second heat transfer fluid in the feed m, and a first closed-loop flow controller, which is the slave controller and has its associated flow sensor F1 that detects the mass flow of the second heat transfer fluid in the feed m.

[0225] The closed-loop control preferably calculates any difference between the current measured temperature of the second heat transfer fluid in the feed m and a defined setpoint value. Therefore, based on this difference, the setpoint value of the slave controller is transmitted to the first closed-loop flow controller, which calculates the difference between the current measured mass flow rate of the second heat transfer fluid in the feed m and the setpoint value determined by the master controller. Based on the difference calculated in this way by the slave controller, the first-stage loop valve 16 is controlled accordingly.

[0226] In this configuration, heat exchanger unit 13 is designed such that during operation of the waste heat recovery system, steam is generated from demineralized water s supplied in conduit p, and this steam is supplied to compressor 18 via conduit q and thus compressed. The mass flow of the compressed steam r is then extracted from the system.

[0227] A valve 17 having a second closed-loop flow controller and its associated flow sensor F3 is used to regulate the mass flow of demineralized water s in the feed p of the heat exchanger unit 13, wherein the closed-loop control is based on a second closed-loop temperature controller having a temperature sensor T4 having its associated temperature sensor for detecting the mass flow temperature of the second heat transfer fluid in the detection conduit o.

[0228] Preferably, when determining the mass flow rate of the demineralized water s in conduit p, the difference between the detected temperatures T4 of the second heat transfer fluid in conduit o is calculated, wherein the setpoint value is calculated based on this difference. Subsequently, this setpoint value is transmitted to a second closed-loop flow controller with its associated flow sensor F3, wherein the second closed-loop flow controller acts as a slave controller. The second closed-loop flow controller calculates the difference between the flow rate of the demineralized water s in conduit p and the setpoint value transmitted to it, using this difference to set the mass flow rate of the demineralized water s in conduit p based on the calculated difference.

[0229] A closed-loop load controller UC, equipped with its associated sensors (including mass flow sensor F2 and temperature sensors T4 and T1), detects the difference between the heat flow rate of the second heat transfer fluid in conduit o and the heat flow rate of the second heat transfer fluid in conduit n, and uses this difference to calculate the difference between the detected heat flow rate difference and a defined load setpoint. Based on this difference, the setpoint is determined and transmitted to a third closed-loop flow controller, which acts as a slave controller and has its associated mass flow sensor F2. The difference between the mass flow rate of the second heat transfer fluid in conduit o, calculated by the slave controller, and the setpoint value determined by the closed-loop load controller UC, is used as the basis for the closed-loop control of the second-stage loop valve 12 and thus for adjusting the mass flow rate of the second heat transfer fluid in conduit o.

[0230] In the first embodiment, the defined load setpoint based on the heat flow difference is determined by a second closed-loop fill level controller located in the first thermal storage unit 10 and having its associated fill level sensor L1_2, wherein the second closed-loop fill level controller is the master controller, preferably a P controller. The second closed-loop fill level controller calculates the difference between the fill level of the first thermal storage unit 10 and the defined setpoint. Based on this difference, the setpoint value of the closed-loop load controller UC is calculated and transmitted to the closed-loop load controller UC.

[0231] The second closed-loop fill level controller, which has its associated fill level controller L1_2, can detect continuous fill level values ​​in the first thermal storage unit 10 and determine the load setpoint of the closed-loop load controller UC based on the detected fill level values, wherein the detected fill level values ​​are limited to a range from a defined minimum fill level value to a defined maximum fill level value.

[0232] In the second embodiment, the load setpoint for limiting the heat flow difference is determined based on the fill level in the first thermal storage unit 10, wherein the setpoint value can only be switched between a "maximum steam generation" mode and a "minimum steam generation" mode. In this case, the "maximum steam generation" mode means that the fill level in the thermal storage unit 10 reaches or exceeds a first limit value, while the "minimum steam generation" mode means that the fill level in the thermal storage unit 10 exceeds a second limit value but does not reach the first limit value.

[0233] If the fill level falls below the second limit, the heat recovery system is shut down, and therefore no more steam is generated.

[0234] The advantage of the first embodiment is that it is easier to implement in a process control system. The disadvantage is that the setpoint value for the heat flow difference can be any value between the "maximum steam production" mode and the "minimum steam production" mode. Therefore, this is a continuous closed-loop control operation.

[0235] The advantage of the second embodiment is that the closed-loop load controller UC operates essentially either in "minimum steam production" mode or "maximum steam production" mode, and not in between. Therefore, this is a discontinuous closed-loop control operation.

[0236] This discontinuous closed-loop control operation is advantageous for compressor 18 because the compressor does not need to constantly change its operating mode.

[0237] Operation based on such Figure 1 The first embodiment of the method for the waste heat recovery system of the above-mentioned waste heat recovery system of the present invention includes the following steps when at least one reactor 2 is running:

[0238] • Reactant mass streams a and b are fed into batch reactor 2, wherein the two reactants can be pre-mixed in mixer 1.

[0239] • An exothermic reaction is performed in batch reactor 2, and batch reactor 2 is cooled by a first heat transfer fluid flowing through the first heat exchanger 9. A first primary loop valve 6 is used here for closed-loop control of the mass flow of the first heat transfer fluid at the inlet of the feed f of the process heat exchanger 7, wherein the closed-loop control is based on a first closed-loop fill level controller of the first thermal storage unit 10 with an associated fill level sensor L1_1. The closed-loop control method preferably involves calculating the difference between the currently measured fill level and a predetermined value, and then using this difference as the basis for adjusting the first primary loop valve 6. The aim is to recover as much heat of reaction as possible. This means that the primary loop valve 6 should generally be preferentially closed, and the second primary loop valve 8 in the feed j should generally be preferentially opened, wherein the second primary loop valve 8 is generally used to control the mass flow of the first heat transfer fluid to the first heat exchanger 9. However, if compressor 18 is already operating at maximum power and the fill level of the first heat storage unit 10 exceeds a predetermined value, the first closed-loop fill level controller, with its associated closed-loop fill level controller L1_1, throttles valve 8 and opens valve 6, allowing at least a portion of the product stream d to enter process heat exchanger 7 without flowing through the first heat exchanger 9. This may be necessary if the amount of heat from the reactor is greater than the amount designed for the heat recovery system.

[0240] The process heat exchanger 7 can control the temperature of the first heat transfer fluid from feed f and feed k. The temperature-controlled first heat transfer fluid is then added to the mixer 1 through conduit i. The cooling or heating medium for the process heat exchanger 7 is fed into the process heat exchanger 7 through feed g and withdrawn from the process heat exchanger 7 through conduit h.

[0241] When the heat recovery system is running, process heat exchanger 7 is typically in standby mode and therefore not operational. Cooling occurs in the first heat exchanger 9, and process heat exchanger 7 only undertakes the task of cooling a portion of the product stream d when heat cannot be recovered by the heat recovery system.

[0242] • A portion of the heat from the first heat transfer fluid is transferred to the second heat transfer fluid via the first heat exchanger 9.

[0243] The second heat transfer fluid at the outlet of the first heat exchanger 9 has a temperature ranging from 30°C to 1500°C and an absolute pressure ranging from 0.1 bar to 400 bar, while the second heat transfer fluid at the inlet of the first heat exchanger 9 has a temperature ranging from 10°C to 1450°C and an absolute pressure ranging from 0.1 bar to 400 bar.

[0244] The first heat transfer fluid at the outlet of the first heat exchanger 9 has a temperature in the range of 30°C to 1500°C and an absolute pressure in the range of 0.1 bar to 400 bar, and the first heat transfer fluid at the inlet of the first heat exchanger 9 has a temperature in the range of 35°C to 1500°C and an absolute pressure in the range of 0.1 bar to 400 bar.

[0245] • A heated second heat transfer fluid is fed into the first heat storage unit 10, wherein the second heat transfer fluid in the first heat storage unit 10 is at a temperature in the range of 30°C to 1500°C and an absolute pressure in the range of 0.1 bar to 400 bar.

[0246] • The second heat transfer fluid is fed from the first heat storage unit 10 to the heat exchanger unit 13 via the first-stage circulation pump 11, wherein the mass flow of the second heat transfer fluid is controlled in a closed loop by the second-stage loop valve 12 located between the first heat storage unit 10 and the second heat storage unit 14 along the main flow direction.

[0247] Furthermore, the temperature of the second heat transfer fluid at the inlet of heat exchanger unit 13 is in the range of 30°C to 1500°C, and the absolute pressure at the inlet of heat exchanger unit 13 is in the range of 0.1 bar to 400 bar.

[0248] Furthermore, the temperature of the second heat transfer fluid at the outlet of heat exchanger unit 13 is in the range of 10°C to 1450°C, and the absolute pressure at the outlet of heat exchanger unit 13 is in the range of 0.1 bar to 400 bar.

[0249] The closed-loop load controller UC, equipped with its associated sensors (including mass flow sensor F2 and temperature sensors T4 and T1), detects the difference between the heat flow rate of the second heat transfer fluid in conduit o and the heat flow rate of the second heat transfer fluid in conduit n, and calculates the difference between the detected heat flow rate difference and a defined load setpoint. This difference is transmitted as a setpoint value to a third closed-loop flow controller, which is a slave controller and has its associated mass flow sensor F2. The difference between the mass flow rate of the second heat transfer fluid in conduit o, calculated by the slave controller, and the setpoint value determined by the closed-loop load controller UC, is used as the basis for the closed-loop control of the second-stage loop valve 12, and thus performs closed-loop control of the mass flow rate of the second heat transfer fluid in conduit o.

[0250] In the first embodiment, the load setpoint defined by the heat flow difference is determined by a second closed-loop fill level controller located in the first thermal storage unit 10 and having its associated fill level sensor L1_2, wherein the second closed-loop fill level controller is preferably a P controller. The second closed-loop fill level controller transmits the setpoint value to the closed-loop load controller UC based on the fill level of the first thermal storage unit 10. This setpoint value corresponds to the load setpoint defined by the heat flow difference.

[0251] In the second embodiment, the load setpoint defined by the heat flow difference is determined here based on the fill level in the first thermal storage unit 10, wherein the load setpoint can be switched between a "maximum steam generation" mode and a "minimum steam generation" mode.

[0252] In this context, the "maximum steam generation" mode means that the filling level in the thermal storage unit 10 reaches or exceeds the first limit value, while the "minimum steam generation" mode means that the filling level in the thermal storage unit 10 exceeds the second limit value but does not reach the first limit value.

[0253] If the fill level falls below the second limit, the heat recovery system is shut down, and therefore no more steam is generated.

[0254] The advantage of the first embodiment is that it is easier to implement in a process control system. The disadvantage is that the setpoint for the heat flow difference can be any value between the "maximum steam production" mode and the "minimum steam production" mode. Therefore, this is a continuous closed-loop control operation.

[0255] The advantage of the second embodiment is that the closed-loop load controller UC operates essentially either in "minimum steam production" mode or "maximum steam production" mode, and not in between. Therefore, this is a discontinuous closed-loop control operation.

[0256] This discontinuous closed-loop control operation is advantageous for compressor 18 because the compressor does not need to constantly change its operating mode.

[0257] • The demineralized water s is fed into the heat exchanger unit 13 via the feed p outside the secondary loop, wherein the demineralized water s at the inlet of the heat exchanger unit 13 is at a temperature in the range of 5°C to 400°C and an absolute pressure in the range of 0.001 bar to 300 bar.

[0258] A valve 17 having a second closed-loop flow controller and its associated flow sensor F3 is used here to regulate the mass flow of demineralized water s in the feed p of the heat exchanger unit 13, wherein the closed-loop control is based on a second closed-loop temperature controller having a temperature sensor T4 having its associated temperature sensor for the mass flow of the second heat transfer fluid in the detection conduit o.

[0259] Preferably, when determining the mass flow rate of the demineralized water s in conduit p, the difference between the detected temperatures T4 of the second heat transfer fluid in conduit o is calculated. Based on this difference, a setpoint value is calculated and transmitted to a second closed-loop flow controller with its associated flow sensor F3, wherein the second closed-loop flow controller acts as a slave controller. The second closed-loop flow controller calculates the difference between the flow rate of the demineralized water s in conduit p and the setpoint value transmitted to it, and valve 17 sets the mass flow rate of the demineralized water s in conduit p based on this calculated difference.

[0260] • Steam is generated in heat exchanger unit 13 by heat supplied from the second heat transfer fluid, wherein the steam at the steam outlet of heat exchanger unit 13 is at a temperature in the range of 5°C to 373°C and an absolute pressure in the range of 0.001 bar to 220 bar.

[0261] • Steam from the steam outlet of heat exchanger unit 13 is fed into compressor 18 via a separate connecting conduit q outside the secondary loop. The compressor compresses the steam to an absolute pressure in the range of 0.5 bar to 220 bar, and the temperature of the steam at the outlet of at least one compressor 18 is correspondingly in the range of 80°C to 373°C.

[0262] • A second heat transfer fluid is fed from heat exchanger unit 13 into second heat storage unit 14, wherein the second heat transfer fluid in second heat storage unit 14 is at a temperature in the range of 10°C to 1450°C and an absolute pressure in the range of 0.1 bar to 400 bar.

[0263] • The second heat transfer fluid is fed from the second heat storage unit 14 into the first heat exchanger 9, thus completing the secondary loop.

[0264] The primary loop valve 16 is used to control the mass flow in the feed l of the first heat exchanger 9, and the closed-loop control is performed based on a first closed-loop temperature controller, which is the master controller and has an associated temperature sensor T3 that detects the temperature of the second heat transfer fluid in the feed m, and a first closed-loop flow controller, which is the slave controller and has an associated flow sensor F1 that detects the mass flow of the second heat transfer fluid in the feed m.

[0265] The closed-loop control preferably calculates any difference between the current measured temperature of the second heat transfer fluid in the feed m and a predetermined value. Therefore, based on this difference, the setpoint value of the slave controller is transmitted to the first closed-loop flow controller, which calculates the difference between the current measured mass flow rate of the second heat transfer fluid in the feed m and the setpoint value determined by the master controller. Based on the difference calculated in this way by the slave controller, the first-stage loop valve 16 is controlled accordingly.

[0266] And the following steps are included when reactor 2 is not running:

[0267] • A second heat transfer fluid is fed from the first heat storage unit 10 into the heat exchanger unit 13, wherein the mass flow rate of the second heat transfer fluid is controlled in a closed loop by a second-stage loop valve 12 located between the first heat storage unit 10 and the second heat storage unit 14 along the main flow direction, and the temperature of the second heat transfer fluid at the inlet of the heat exchanger unit 13 is in the range of 30°C to 1500°C, and the absolute pressure at the inlet of the heat exchanger unit 13 is in the range of 0.1 bar to 400 bar.

[0268] • The demineralized water s is fed into the heat exchanger unit 13 via the feed p outside the secondary loop, wherein the demineralized water at the inlet of the heat exchanger unit 13 is at a temperature in the range of 5°C to 400°C and an absolute pressure in the range of 0.001 bar to 300 bar.

[0269] A valve 17 having a second closed-loop flow controller and its associated flow sensor F3 is used here to regulate the mass flow of demineralized water s in the feed p of the heat exchanger unit 13, wherein the closed-loop control is based on a second closed-loop temperature controller having a temperature sensor T4 having its associated temperature sensor for the mass flow of the second heat transfer fluid in the detection conduit o.

[0270] Preferably, when determining the mass flow rate of the demineralized water s in conduit p, the difference between the detected temperatures T4 of the second heat transfer fluid in conduit o is calculated. Based on this difference, a setpoint value is calculated and transmitted to a second closed-loop flow controller with its associated flow sensor F3, wherein the second closed-loop flow controller acts as a slave controller. The second closed-loop flow controller calculates the difference between the flow rate of the demineralized water s in conduit p and the setpoint value transmitted to it, and valve 17 sets the mass flow rate of the demineralized water s in conduit p based on this calculated difference.

[0271] • Steam is generated in heat exchanger unit 13 by heat supplied from the second heat transfer fluid, wherein the steam at the outlet of heat exchanger unit 13 is at a temperature in the range of 5°C to 373°C and an absolute pressure in the range of 0.001 bar to 220 bar.

[0272] • Steam from heat exchanger unit 13 is fed to compressor 18 via conduit q, which compresses the steam to an absolute pressure in the range of 0.5 bar to 220 bar, and the temperature of the steam at the outlet of at least one compressor 18 is correspondingly in the range of 80°C to 373°C.

[0273] • A second heat transfer fluid is fed from heat exchanger unit 13 into second heat storage unit 14, wherein the second heat transfer fluid in second heat storage unit 14 is at a temperature in the range of 10°C to 1450°C and an absolute pressure in the range of 0.1 bar to 400 bar.

[0274] • The mass flow of the second heat transfer fluid along the main flow direction between the second heat storage unit 14 and the first heat storage unit 10 is blocked by cutting off the mass flow via a primary loop valve 16 located between the second heat storage unit 14 and the first heat storage unit 10 along the main flow direction.

[0275] Figure 2 A process flow diagram and schematic diagram of the industrial process of the waste heat recovery system according to a second embodiment of the waste heat recovery system and the method of the present invention are shown.

[0276] A second embodiment of the invention for a waste heat recovery system for generating steam for chemical industrial facilities includes a coolable batch reactor 2 connected to the primary loop, wherein the batch reactor 2 is designed such that an exothermic reaction of the reaction mixture occurs during operation of the batch reactor 2. In this case, two reactant mass streams a and b are mixed through a mixer 1 and then fed into the batch reactor 2. Optionally, an additional reactant stream c can be fed into the batch reactor through a separate feed and a separate inlet.

[0277] To cool the batch reactor 2 driven by the primary circulation pump 4, the reaction mixture itself flows as the first heat transfer fluid through the primary loop, which fluidly connects the batch reactor 2 to the first heat exchanger 9 via conduits d and j, such that the first heat transfer fluid is cooled in the first heat exchanger 9 and then returned to the mixer 1 via conduit i to cool the batch reactor 2. The flow rate of the reaction mixture leaving the system can be adjusted by valve 5.

[0278] The first primary loop valve 6 is used for closed-loop control of the mass flow of the first heat transfer fluid at the inlet of the feed f of the process heat exchanger 7, wherein the closed-loop control is based on a first closed-loop fill level controller of the first thermal storage unit 10 with an associated fill level sensor L1_1. The closed-loop control method preferably involves calculating the difference between the currently measured fill level and a predetermined value, and then using this difference as the basis for adjusting the first primary loop valve 6.

[0279] The goal is to recover as much heat of reaction as possible. This means that primary loop valve 6 should generally be closed first, and second primary loop valve 8 in feed j should generally be opened first, wherein second primary loop valve 8 is generally used to control the mass flow of the first heat transfer fluid to the first heat exchanger 9.

[0280] The process heat exchanger 7 can control the temperature of the first heat transfer fluid from feed f and feed k. The temperature-controlled first heat transfer fluid is then added to the mixer 1 through conduit i. The cooling or heating medium for the process heat exchanger 7 is fed into the process heat exchanger 7 through feed g and withdrawn from the process heat exchanger 7 through conduit h.

[0281] When the heat recovery system is running, process heat exchanger 7 is typically in standby mode and therefore not operational. Cooling occurs in the first heat exchanger 9, and process heat exchanger 7 only undertakes the task of cooling a portion of the product stream d when heat cannot be recovered by the heat recovery system.

[0282] The mass flow of the first heat transfer fluid is cooled by the first heat exchanger 9 and added to the mass flow of the first heat transfer fluid in the conduit f through the conduit k.

[0283] A separate secondary loop includes a second heat transfer fluid and is connected to the first heat exchanger 9 in such a way that the second heat transfer fluid is heated by the first heat transfer fluid during operation of the batch reactor 2. Specifically, the second heat transfer fluid flows into the first heat exchanger 9 through conduit l, where it is heated by the first heat transfer fluid on the primary loop side of the first heat exchanger 9, and is then fed into the first thermal storage unit 10 through feed m.

[0284] The secondary loop begins at the first heat exchanger 9 and is fluidly connected downstream to the first thermal storage unit 10 via feed m. It is then fluidly connected via conduit n to the flash tank unit 13 downstream of the first thermal storage unit 10, fluidly connected via conduit o to the second thermal storage unit 14 downstream of the flash tank unit 13, and fluidly connected via conduit l to the first heat exchanger 9 downstream of the second thermal storage unit 14. This completes the secondary loop. The first-stage circulation pump 11 delivers the second heat transfer fluid from the first thermal storage unit 10 to the flash tank unit 13 via conduit n. The second-stage circulation pump 15 delivers the second heat transfer fluid from the second thermal storage unit 14 to the first heat exchanger 9 via conduit l. The third-stage loop pump 19 here delivers the second heat transfer fluid from the flash tank unit 13 to the second thermal storage unit 14.

[0285] The primary loop valve 16 is used to control the mass flow in the feed l of the first heat exchanger 9, wherein the closed-loop control is performed based on a first closed-loop temperature controller, which is the master controller and has an associated temperature sensor T3 that detects the temperature of the second heat transfer fluid in the feed m, and a first closed-loop flow controller, which is the slave controller and has an associated flow sensor F1 that detects the mass flow of the second heat transfer fluid in the feed m.

[0286] The closed-loop control preferably calculates any difference between the current measured temperature of the second heat transfer fluid in the feed m and a predetermined value. Therefore, based on this difference, the setpoint value of the slave controller is transmitted to the first closed-loop flow controller, which calculates the difference between the current measured mass flow rate of the second heat transfer fluid in the feed m and the setpoint value determined by the master controller. Based on the difference calculated in this way by the slave controller, the first-stage loop valve 16 is controlled accordingly.

[0287] In this configuration, the flash tank unit 13 is designed such that during operation of the waste heat recovery system, steam is generated from demineralized water s supplied in conduit p, and this steam is supplied to compressor 18 via conduit q and thus compressed. The mass flow of the compressed steam r is then extracted from the system.

[0288] Valve 17 is used to regulate the mass flow of demineralized water s in the feed p of flash tank unit 13, wherein the closed-loop control is based on a second closed-loop temperature controller with a temperature sensor T4 having the temperature of the mass flow of the second heat transfer fluid in the associated detection conduit o.

[0289] Preferably, when determining the mass flow rate of the demineralized water s in conduit p, the difference between the detected temperatures T4 of the second heat transfer fluid in conduit o is calculated. Based on this difference, a setpoint value is calculated and transmitted to a second closed-loop flow controller with its associated flow sensor F3, wherein the second closed-loop flow controller acts as a slave controller. The second closed-loop flow controller calculates the difference between the flow rate of the demineralized water s in conduit p and the setpoint value transmitted to it, and valve 17 sets the mass flow rate of the demineralized water s in conduit p based on this calculated difference.

[0290] A closed-loop load controller UC, equipped with its associated sensors (including mass flow sensor F2 and temperature sensors T4 and T1), detects the difference between the heat flow rate of the second heat transfer fluid in conduit o and the heat flow rate of the second heat transfer fluid in conduit n, and calculates the difference between the detected heat flow rate difference and a defined load setpoint. Based on this difference, a setpoint value is calculated and transmitted to a third closed-loop flow controller, which acts as a slave controller and has its associated mass flow sensor F2. The difference between the mass flow rate of the second heat transfer fluid in conduit o, calculated by the slave controller, and the setpoint value determined by the closed-loop load controller UC, is used as the basis for the closed-loop control of the second-stage loop valve 12, and thus the mass flow rate of the second heat transfer fluid in conduit o is controlled in a closed loop.

[0291] In a first embodiment, the load setpoint defined by the heat flow difference is determined by a second closed-loop fill level controller, preferably a P controller, located in the first thermal storage unit 10 and having its associated fill level sensor L1_2. The second closed-loop fill level controller transmits the setpoint value to the closed-loop load controller UC based on the fill level of the first thermal storage unit 10. This setpoint value corresponds to the load setpoint defined by the heat flow difference.

[0292] In the second embodiment, the load setpoint defined by the heat flow difference is determined here based on the fill level in the first thermal storage unit 10, wherein the load setpoint can be switched between a "maximum steam generation" mode and a "minimum steam generation" mode.

[0293] In this context, the "maximum steam generation" mode means that the filling level in the thermal storage unit 10 reaches or exceeds the first limit value, while the "minimum steam generation" mode means that the filling level in the thermal storage unit 10 exceeds the second limit value but does not reach the first limit value.

[0294] If the fill level falls below the second limit, the heat recovery system is shut down, and therefore no more steam is generated.

[0295] The advantage of the first embodiment is that it is easier to implement in a process control system. The disadvantage is that the setpoint for the heat flow difference can be any value between the "maximum steam production" mode and the "minimum steam production" mode. Therefore, this is a continuous closed-loop control operation.

[0296] The advantage of the second embodiment is that the closed-loop load controller UC operates essentially either in "minimum steam production" mode or "maximum steam production" mode, and not in between. Therefore, this is a discontinuous closed-loop control operation.

[0297] This discontinuous closed-loop control operation is advantageous for compressor 18 because the compressor does not need to constantly change its operating mode.

[0298] Operation based on such Figure 2 The second embodiment of the method for waste heat recovery system of the above-mentioned waste heat recovery system of the present invention includes the following steps when at least one reactor 2 is running:

[0299] • Reactant mass streams a and b are fed into batch reactor 2, wherein the two reactants can be pre-mixed in mixer 1.

[0300] • An exothermic reaction is performed in batch reactor 2, and batch reactor 2 is cooled by a first heat transfer fluid flowing through the first heat exchanger 9. A first primary loop valve 6 is used here for closed-loop control of the mass flow of the first heat transfer fluid at the inlet of the feed f of the process heat exchanger 7, wherein the closed-loop control is based on a first closed-loop fill level controller with an associated fill level sensor L1_1 of the first thermal storage unit 10. The closed-loop control method preferably involves calculating the difference between the currently measured fill level and a predetermined value, and then using this difference as the basis for adjusting the first primary loop valve 6. The aim is to recover as much heat of reaction as possible. This means that the primary loop valve 6 should generally be preferentially closed, and the second primary loop valve 8 in the feed j should generally be preferentially opened, wherein the second primary loop valve 8 is generally used to control the mass flow of the first heat transfer fluid to the first heat exchanger 9. However, if the compressor 18 is already operating at maximum power and the fill level of the first thermal storage unit 10 exceeds a predetermined value, the first closed-loop fill level controller throttles valve 8 and opens valve 6, so that at least a portion of the product stream d enters the process heat exchanger 7 without flowing through the first heat exchanger 9. This may be necessary if the amount of heat from the reactor is greater than the amount the heat recovery system is designed to handle.

[0301] The process heat exchanger 7 can control the temperature of the first heat transfer fluid from feed f and feed k. The temperature-controlled first heat transfer fluid is then added to the mixer 1 through conduit i. The cooling or heating medium for the process heat exchanger 7 is fed into the process heat exchanger 7 through feed g and withdrawn from the process heat exchanger 7 through conduit h.

[0302] When the heat recovery system is running, process heat exchanger 7 is typically in standby mode and therefore not operational. Cooling occurs in the first heat exchanger 9, and process heat exchanger 7 only undertakes the task of cooling a portion of the product stream d when heat cannot be recovered by the heat recovery system.

[0303] • A portion of the heat from the first heat transfer fluid is transferred to the second heat transfer fluid via the first heat exchanger 9.

[0304] The second heat transfer fluid at the outlet of the first heat exchanger 9 has a temperature ranging from 30°C to 1500°C and an absolute pressure ranging from 0.1 bar to 400 bar, while the second heat transfer fluid at the inlet of the first heat exchanger 9 has a temperature ranging from 10°C to 1450°C and an absolute pressure ranging from 0.1 bar to 400 bar.

[0305] The first heat transfer fluid at the outlet of the first heat exchanger 9 has a temperature in the range of 30°C to 1500°C and an absolute pressure in the range of 0.1 bar to 400 bar, and the first heat transfer fluid at the inlet of the first heat exchanger 9 has a temperature in the range of 35°C to 1500°C and an absolute pressure in the range of 0.1 bar to 400 bar.

[0306] • A heated second heat transfer fluid is fed into the first heat storage unit 10, wherein the second heat transfer fluid in the first heat storage unit 10 is at a temperature in the range of 30°C to 1500°C and an absolute pressure in the range of 0.1 bar to 400 bar.

[0307] • The second heat transfer fluid is fed from the first heat storage unit 10 to the flash tank unit 13 via the first-stage circulation pump 11, wherein the mass flow of the second heat transfer fluid is controlled in a closed loop by the second-stage loop valve 12 located between the first heat storage unit 10 and the second heat storage unit 14 along the main flow direction.

[0308] Furthermore, the temperature of the second heat transfer fluid at the inlet of the flash tank unit 13 is in the range of 30°C to 1500°C, and the absolute pressure at the inlet of the flash tank unit 13 is in the range of 0.1 bar to 400 bar.

[0309] Furthermore, the temperature of the second heat transfer fluid at the outlet of flash tank unit 13 is in the range of 10°C to 1450°C, and the absolute pressure at the outlet of flash tank unit 13 is in the range of 0.1 bar to 400 bar.

[0310] The closed-loop load controller UC, equipped with its associated sensors (including mass flow sensor F2 and temperature sensors T4 and T1), detects the difference between the heat flow rate of the second heat transfer fluid in conduit o and the heat flow rate of the second heat transfer fluid in conduit n, and calculates the difference between the detected heat flow rate difference and a defined load setpoint. Based on this difference, the setpoint value is calculated and transmitted to the third closed-loop flow controller, which acts as a slave controller and has its associated mass flow sensor F2. The difference between the mass flow rate of the second heat transfer fluid in conduit o, calculated by the slave controller, and the setpoint value determined by the closed-loop load controller UC, is used as the basis for the closed-loop control of the second-stage loop valve 12, and thus the mass flow rate of the second heat transfer fluid in conduit o is controlled in a closed loop.

[0311] In a first embodiment, the load setpoint defined by the heat flow difference is determined by a second closed-loop fill level controller, preferably a P controller, located in the first thermal storage unit 10 and having its associated fill level sensor L1_2. The second closed-loop fill level controller transmits the setpoint value to the closed-loop load controller UC based on the fill level of the first thermal storage unit 10. This setpoint value corresponds to the load setpoint defined by the heat flow difference.

[0312] In the second embodiment, the load setpoint defined by the heat flow difference is determined here based on the fill level in the first thermal storage unit 10, wherein the load setpoint can be switched between a "maximum steam generation" mode and a "minimum steam generation" mode.

[0313] In this context, the "maximum steam generation" mode means that the fill level in the thermal storage unit 10 reaches or exceeds the first limit, while the "minimum steam generation" mode means that the fill level in the thermal storage unit 10 exceeds the second limit but does not reach the first limit. If the fill level is below the second limit, the heat recovery system is shut down, and therefore no more steam is generated.

[0314] The advantage of the first embodiment is that it is easier to implement in a process control system. The disadvantage is that the setpoint for the heat flow difference can be any value between the "maximum steam production" mode and the "minimum steam production" mode. Therefore, this is a continuous closed-loop control operation.

[0315] The advantage of the second embodiment is that the closed-loop load controller UC operates essentially either in "minimum steam production" mode or "maximum steam production" mode, and not in between. Therefore, this is a discontinuous closed-loop control operation.

[0316] This discontinuous closed-loop control operation is advantageous for compressor 18 because the compressor does not need to constantly change its operating mode.

[0317] • The demineralized water s is fed into the flash tank unit 13 via the feed p outside the secondary loop, wherein the demineralized water s at the inlet of the flash tank unit 13 is at a temperature in the range of 5°C to 400°C and an absolute pressure in the range of 0.001 bar to 300 bar.

[0318] A valve 17 having a second closed-loop flow controller and its associated flow sensor F3 is used here to regulate the mass flow of demineralized water s in the feed p of the flash tank unit 13, wherein the closed-loop control is based on a second closed-loop temperature controller having a temperature sensor T4 having its associated temperature sensor for the mass flow of the second heat transfer fluid in the detection conduit o.

[0319] Preferably, when determining the mass flow rate of the demineralized water s in conduit p, the difference between the detected temperatures T4 of the second heat transfer fluid in conduit o is calculated. Based on this difference, a setpoint value is calculated and transmitted to a second closed-loop flow controller with its associated flow sensor F3, wherein the second closed-loop flow controller acts as a slave controller. The second closed-loop flow controller calculates the difference between the flow rate of the demineralized water s in conduit p and the setpoint value transmitted to it, and valve 17 sets the mass flow rate of the demineralized water s in conduit p based on this calculated difference.

[0320] • Steam is generated in flash tank unit 13 by heat supplied from a second heat transfer fluid, wherein the steam at the steam outlet of flash tank unit 13 is at a temperature in the range of 5°C to 373°C and an absolute pressure in the range of 0.001 bar to 220 bar.

[0321] • Steam from the steam outlet of the flash tank unit 13 is fed into compressor 18 via a separate connecting conduit q outside the secondary circuit. The compressor compresses the steam to an absolute pressure in the range of 0.5 bar to 220 bar, and the temperature of the steam at the outlet of at least one compressor 18 is correspondingly in the range of 80°C to 373°C.

[0322] • A second heat transfer fluid is fed from the flash tank unit 13 to the second heat storage unit 14 via pump 19, wherein the second heat transfer fluid in the second heat storage unit 14 is at a temperature in the range of 10°C to 1450°C and an absolute pressure in the range of 0.1 bar to 400 bar.

[0323] • The second heat transfer fluid is fed from the second heat storage unit 14 into the first heat exchanger 9, thus completing the secondary loop.

[0324] The primary loop valve 16 is used to control the mass flow in the feed l of the first heat exchanger 9, and the closed-loop control is performed based on a first closed-loop temperature controller, which is the master controller and has an associated temperature sensor T3 that detects the temperature of the second heat transfer fluid in the feed m, and a first closed-loop flow controller, which is the slave controller and has an associated flow sensor F1 that detects the mass flow of the second heat transfer fluid in the feed m.

[0325] The closed-loop control preferably calculates any difference between the current measured temperature of the second heat transfer fluid in the feed m and a predetermined value. Based on this difference, the setpoint value of the slave controller is transmitted to the first closed-loop flow controller, which calculates the difference between the current measured mass flow rate of the second heat transfer fluid in the feed m and the setpoint value determined by the master controller. Based on the difference calculated in this way by the slave controller, the first-stage loop valve 16 is controlled accordingly.

[0326] And the following steps are included when reactor 2 is not running:

[0327] • A second heat transfer fluid is fed from the first heat storage unit 10 into the flash tank unit 13, wherein the mass flow of the second heat transfer fluid is controlled in a closed loop by a secondary loop valve 12 located between the first heat storage unit 10 and the second heat storage unit 14 along the main flow direction, and the temperature of the second heat transfer fluid at the inlet of the flash tank unit 13 is in the range of 30°C to 1500°C, and the absolute pressure at the inlet of the flash tank unit 13 is in the range of 0.1 bar to 400 bar.

[0328] • The demineralized water is fed into the flash tank unit 13 via a feed p outside the secondary loop, wherein the demineralized water at the inlet of the flash tank unit 13 is at a temperature in the range of 5°C to 400°C and an absolute pressure in the range of 0.001 bar to 300 bar.

[0329] A valve 17 having a second closed-loop flow controller and its associated flow sensor F3 is used here to regulate the mass flow of demineralized water s in the feed p of the flash tank unit 13, wherein the closed-loop control is based on a second closed-loop temperature controller having a temperature sensor T4 having its associated temperature sensor for the mass flow of the second heat transfer fluid in the detection conduit o.

[0330] Preferably, when determining the mass flow rate of the demineralized water s in conduit p, the difference between the detected temperatures T4 of the second heat transfer fluid in conduit o is calculated. Based on this difference, a setpoint value is calculated and transmitted to a second closed-loop flow controller with its associated flow sensor F3, wherein the second closed-loop flow controller acts as a slave controller. The second closed-loop flow controller calculates the difference between the flow rate of the demineralized water s in conduit p and the setpoint value transmitted to it, and valve 17 sets the mass flow rate of the demineralized water s in conduit p based on this calculated difference.

[0331] • Steam is generated in flash tank unit 13 by heat supplied from the second heat transfer fluid, wherein the steam at the outlet of flash tank unit 13 is at a temperature in the range of 5°C to 373°C and an absolute pressure in the range of 0.001 bar to 220 bar.

[0332] • Steam from flash tank unit 13 is fed into compressor 18 via conduit q, which compresses the steam to an absolute pressure in the range of 0.5 bar to 220 bar, and the temperature of the steam at the outlet of at least one compressor 18 is correspondingly in the range of 80°C to 373°C.

[0333] • A second heat transfer fluid is fed from the flash tank unit 13 to the second heat storage unit 14 via pump 19, wherein the second heat transfer fluid in the second heat storage unit 14 is at a temperature in the range of 10°C to 1450°C and an absolute pressure in the range of 0.1 bar to 400 bar.

[0334] • The mass flow of the second heat transfer fluid along the main flow direction between the second heat storage unit 14 and the first heat storage unit 10 is blocked by cutting off the mass flow via a primary loop valve 16 located between the second heat storage unit 14 and the first heat storage unit 10 along the main flow direction.

[0335] Figure 5 A process flow diagram and schematic diagram of the industrial process of the waste heat recovery system according to a third embodiment of the waste heat recovery system and the method of the present invention are shown.

[0336] according to Figure 5 The third embodiment of the waste heat recovery system of the present invention for generating steam for chemical industrial facilities and according to... Figure 1 The first embodiment and according to Figure 2 The second embodiment differs in that it uses a layered storage device 20, which replaces the two thermal storage units 10 and 14. According to... Figure 5 The third embodiment of the method of the present invention and according to Figure 1 The first embodiment and according to Figure 2 The second embodiment differs in that it is subject to closed-loop control regulation caused by the layered storage device 20.

[0337] The preferred closed-loop control concept when using the stratified storage device 20 depends on the discrete switching of the temperature distribution of the liquid in the stratified storage device 20.

[0338] In a preferred embodiment, the closed-loop control system includes components arranged according to... Figure 5 At least four temperature sensors T1, T2, T5 and T6 are located at the height of the tiered storage device 20.

[0339] Based on the temperatures measured at these locations, there should be discrete switching between the "no recovery" and "minimum recovery" states, and between the "minimum recovery" and "maximum recovery" states. The compressor 18, which compresses the steam generated by the evaporator unit 13, operates according to the following discrete states: "no recovery," "minimum recovery," and "maximum recovery." For example, when the value is "maximum recovery," the compressor 18 operates at maximum load. If the value is "no recovery," the compressor 18 is shut down. If the value is "minimum recovery," the compressor 18 operates at a load ranging from 30% to 90% of full load, preferably from 60% to 80%. This discrete closed-loop control logic also serves as the basis for determining the setpoint value of the closed-loop controller UC.

[0340] For example, discrete states can be determined as follows:

[0341] according to Figure 5 Temperature sensors T1, T2, T5 and T6 are arranged from top to bottom in the layered storage device 20 at the height of the layered storage device.

[0342] At the start of the process, the stratified storage device 20 is filled with cold fluid and the discrete state is set to "no recovery".

[0343] When the temperature of temperature sensor T2 is greater than the predetermined value T 热 At this time, the discrete state is set to "minimum recovery". When the temperature of temperature sensor T1 drops below a predetermined value T from the "minimum recovery" state... 冷 The discrete state is changed from "minimum recycling" to "no recycling".

[0344] When the temperature of temperature sensor T6 exceeds the predetermined value T when starting from the "minimum recovery" state... 热 At that time, the status is set to "maximum recycling".

[0345] When the temperature of temperature sensor T5 is lower than the predetermined value T when starting from the "maximum recovery" state. 冷 At that time, the status is set to "minimum recycling".

[0346] These switching mechanisms typically begin immediately when the conditions are met, but occur over a certain period of time to avoid large, immediate changes in the load on compressor 18. Therefore, the transition from "minimum recovery" to "maximum recovery" should occur within a predetermined time period (e.g., 5 minutes).

[0347] In a preferred embodiment, when using the tiered storage device 20, the closed-loop control system includes an additional closed-loop controller QC to protect the waste heat recovery system from overload. Preferably, this additional closed-loop controller QC replaces the closed-loop fill level controller LC used in variants with two heat storage units.

[0348] This additional closed-loop controller (QC) can, for example, act as a soft sensor using the distribution of liquid density and / or liquid temperature along the height of the tiered storage unit to determine scalar values ​​as actual values. Then, based on... Figure 5 The difference between the actual value and the predetermined setpoint value can be used to set the valve 8 in the feed of the first heat exchanger 9 and the valve 6 in the feed of the process heat exchanger 7.

[0349] In a preferred embodiment, the density determined at the height of the tiered storage device 20 is used as the basis for calculating the amounts of cold and hot fluids in the tiered storage device 20. When the average density substantially corresponds to a predetermined minimum density and thus the entire volume of the tiered storage device 20 is substantially filled with hot fluid, it means that the tiered storage device 20 has reached its maximum storage capacity.

[0350] Therefore, the average density also indirectly indicates the amount of fluid in the stratified storage device 20 at a predetermined maximum permissible temperature. Furthermore, the average density indicates the extent to which the predetermined maximum storage capacity of the stratified storage device 20 has been reached, as well as the amount of steam that the heat recovery system can generate.

[0351] The compressor 18 is preferably already operating at "maximum recovery" with the maximum storage capacity of the stratified storage unit 20. In this case, less of the first heat transfer fluid passes through the first heat exchanger 9.

[0352] Therefore, if the average density of the stratified storage unit 20 over its volume is lower than a predetermined set point, the additional closed-loop controller QC (preferably a PID controller) preferably reduces the heat flow from the reactor 2 to the stratified storage unit 20, specifically according to... Figure 5 Valve 8 in the feed of the first heat exchanger 9 is opened to a smaller extent, while valve 6 in the feed of the process heat exchanger 7 is opened to a larger extent.

[0353] Figure 6 A schematic process flow diagram of a waste heat recovery system according to a third embodiment of the present invention is shown. Figure 6 The third embodiment of the waste heat recovery system of the present invention for generating steam for chemical industrial facilities and according to... Figure 1 The first embodiment differs in that it has an added closed heat pump loop with its associated components.

[0354] In a preferred embodiment of this waste heat recovery system, evaporator unit 13 is a heat exchanger. A closed heat pump loop is also fluidly connected to the secondary side of the heat exchanger 13, and this closed heat pump loop includes a compressor, a Joule-Thomson valve or turbine, and an additional heat exchanger. This additional heat exchanger... Figure 6 It is called a "condenser".

[0355] Compared to valves, turbines can also generate mechanical or electrical energy. The operating medium for a closed heat pump loop can be, for example, water and / or synthetic fluids. Organic fluids, such as pentane or heptane, are also generally suitable as operating media for closed heat pump loops. Preferably, hydrocarbon fluids are used as the operating medium for closed heat pump loops. More preferably, ammonia is used as the operating medium for closed heat pump loops.

[0356] An additional heat exchanger in a closed heat pump loop causes water supplied to its secondary side to evaporate to produce steam. For example, steam with an absolute pressure in the range of 1.5 bar to 2.0 bar can thus be produced. Any downstream compressor can then increase the steam pressure and temperature. Example

[0357] For the following two examples 1 and 2 of the present invention, example 1 uses CENIT software with ModelFit-Cybernetica. Details can be found at the following website: Model Predictive Control - Cybernetica (Visited on September 7, 2023).

[0358] The simulation is based on Figure 1 The simulation of the heat recovery system of the present invention, and the simulation is used for operation according to the present invention. Figure 1 Methods for heat recovery systems.

[0359] The simulation is simplified here because the models of compressor 18 and reactor 2 are not included in the simulation. This is achieved by the following: compressor 18 operates automatically within its load range of 60% to 100% based on the mass flow rate and temperature of the demineralized water p, and reactor 2 delivers a predetermined heat flow rate through conduit d.

[0360] Furthermore, it is assumed that the ideal closed-loop control of the second closed-loop temperature controller with its associated temperature sensor T4 is used to perform closed-loop control of the temperature of the second heat transfer fluid downstream of the evaporator unit 13.

[0361] In addition, there is no heat loss to the environment in the simulation, which means that, for example, the two thermal storage units 10 and 14 do not release any heat to the environment.

[0362] The basic findings of the simulation include the following:

[0363] 1. This simulation tests the closed-loop control concept of a heat recovery system, including a closed-loop control circuit. Therefore, unacceptable temperature exceedances or other undesirable operating points become apparent.

[0364] 2. The simulation tests the filling level in the first thermal storage unit 10 and the second thermal storage unit 14, the temperature upstream of the first thermal storage unit 10 and the second thermal storage unit 14, and the behavior of the heat flow for steam generation in the heat exchanger unit 13.

[0365] 3. The simulation determined the effect of the change in the tank volume of one of the two thermal storage units 10 and 14 on the frequency of compressor 18 starting and stopping.

[0366] 4. This simulation determined the effect of changes in the tank volume of one of the two thermal storage units 10 and 14 on the amount of heat recovered.

[0367] Example 1:

[0368] In Example 1 of the present invention, a continuous closed-loop fill level control system is presented, wherein the heat flow rate for steam generation can take any value between the minimum and maximum heat flow rate for steam generation.

[0369] In this example 1, the evaporator unit 13 is based on Figure 1 The heat exchanger unit. Additionally, in this example 1, the first heat transfer fluid is the reaction mixture from the reactor, and the second heat transfer fluid is demineralized water.

[0370] The following input parameters are used for this simulation:

[0371] 1. The heat flow from reactor 2 is transferred to the simulation model as a function of time.

[0372] 2. The temperature of the first thermal storage unit 10 is 95°C.

[0373] 3. The temperature of the second thermal storage unit 14 is 85°C.

[0374] 4. The first thermal storage unit 10 and the second thermal storage unit 14 each have a tank volume of 2500 m³.

[0375] 5. The fill level setpoint of the first thermal storage unit 10 of the closed-loop load controller UC is based on 31% of the maximum fill level.

[0376] 6. The maximum heat flow generated by the steam is 4359 kW, which means that the compressor will be used at 100% operating load.

[0377] If the filling level of the first thermal storage unit 10 exceeds the maximum allowable filling level, the first heat transfer fluid in the conduit d will be at least partially delivered to the heat exchanger 7 so that the filling level of the first thermal storage unit 10 can be reduced accordingly.

[0378] 7. The ratio between the maximum heat flow for steam generation and the minimum heat flow for steam generation is 1.67 because, in this example 1, compressor 18 will only operate within its load range of 60% to 100%. Therefore, 60% operating load of the compressor corresponds to the minimum heat flow for steam generation, while 100% operating load of the compressor corresponds to the maximum heat flow for steam generation.

[0379] 8. The maximum permissible fill level in the first thermal storage unit 10 is based on 95% of the maximum fill level. Before exceeding this value, the first heat transfer fluid in the conduit d is fed into the heat exchanger 7.

[0380] Set the following initial parameters at the start of the simulation:

[0381] 1. The filling level of the first thermal storage unit 10 is 10% of the maximum filling level of the first thermal storage unit 10.

[0382] 2. The filling level of the second thermal storage unit 14 is based on 90% of the maximum filling level of the second thermal storage unit 14.

[0383] Figure 3 Presented according to Figure 1 The simulation results of the heat recovery system running for 20 days.

[0384] The top drawing uses solid lines to represent the change in the filling level of the first thermal storage unit 10 over time, and dashed lines to represent the filling level of the second thermal storage unit 14 over time, where 1 corresponds to the maximum filling level.

[0385] The middle plot shows the change of two heat flows over time, in kW. Here, the solid line corresponds to the heat flow used for steam generation, while the dashed line corresponds to the heat flow of the first heat transfer fluid from reactor 2 in conduit d.

[0386] The bottom plot shows the temperature change over time, expressed in degrees Celsius. Here, the solid line corresponds to the temperature of the second heat transfer fluid in the first thermal storage unit 10, while the dashed line corresponds to the temperature immediately upstream of the first thermal storage unit 10.

[0387] The simulation in Example 1 shows that the fill levels of the two thermal storage units 10 and 14, as well as the heat flow for steam generation, are kept within permissible limits. The temperature fluctuation of the second heat transfer fluid upstream of the first thermal storage unit 10 is in the range of 85°C to 105°C.

[0388] The heat flow rate used for steam generation can be any value between the minimum and maximum heat flow rates used for steam generation, as set for a closed-loop control system.

[0389] Furthermore, the simulation shows that the cumulative heat flow from reactor 2 over 20 days corresponds to the amount of heat used to generate steam over those 20 days. This is possible because the simulation does not account for any heat loss to the environment.

[0390] Example 2

[0391] Example 2 of the present invention presents a simulation with discontinuous fill level control, wherein the heat flow rate for steam generation can only take one of two discrete values, namely the maximum heat flow rate and the minimum heat flow rate for steam generation.

[0392] Using the same input and initial parameters as in the previous simulation in Example 1, the difference is:

[0393] • The maximum heat flow generated by the steam is 4047 kW, which means that the compressor will be used at 100% operating load.

[0394] If the filling level of the first thermal storage unit 10 exceeds the maximum allowable filling level, the first heat transfer fluid in the conduit d will be at least partially delivered to the heat exchanger 7 so that the filling level of the first thermal storage unit 10 can be reduced accordingly.

[0395] • When the heat recovery system is in operation, the minimum heat flow for steam generation is 2428 kW.

[0396] The ratio between the maximum heat flow for steam generation and the minimum heat flow for steam generation is also 1.67, as in the previous simulation, because compressor 18 will only operate within its load range of 60% to 100%. Therefore, 60% operating load of the compressor corresponds to the minimum heat flow for steam generation, while 100% operating load of the compressor corresponds to the maximum heat flow for steam generation.

[0397] • The threshold for the fill level in the first thermal storage unit 10 is 10% of the maximum fill level, at which the system switches from the “no heat recovery” mode to the “minimum heat recovery” mode.

[0398] • The threshold for the fill level in the first thermal storage unit 10 is 33% of the maximum fill level, at which the system switches from the “minimum heat recovery” mode to the “maximum heat recovery” mode.

[0399] • The threshold for the fill level in the first thermal storage unit 10 is based on 23% of the maximum fill level, at which the system switches from the “maximum heat recovery” mode to the “minimum heat recovery” mode.

[0400] • The threshold for the fill level in the first thermal storage unit 10 is 3% of the maximum fill level, at which the system switches from the “minimum heat recovery” mode to the “no heat recovery” mode.

[0401] Figure 4 Presented according to Figure 1 The simulation results of the heat recovery system running for 20 days.

[0402] The top drawing uses solid lines to represent the change in the filling level of the first thermal storage unit 10 over time, and dashed lines to represent the filling level of the second thermal storage unit 14 over time, where 1 corresponds to the maximum filling level.

[0403] The middle plot shows the change of two heat flows over time, in kW. Here, the solid line corresponds to the heat flow used for steam generation, while the dashed line corresponds to the heat flow of the first heat transfer fluid from reactor 2 in conduit d.

[0404] The bottom plot shows the temperature change over time, expressed in degrees Celsius. Here, the solid line corresponds to the temperature of the second heat transfer fluid in the first thermal storage unit 10, while the dashed line corresponds to the temperature immediately upstream of the first thermal storage unit 10.

[0405] The simulation shows that the fill levels of the two thermal storage units 10 and 14, as well as the heat flow for steam generation, remain within allowable ranges. The temperature fluctuation of the second heat transfer fluid upstream of the first thermal storage unit 10 is in the range of 85°C to 105°C.

[0406] For example, in a closed-loop control system, the heat flow used for steam generation can only be a predetermined minimum heat flow or a predetermined maximum heat flow.

[0407] Furthermore, the simulation shows that the cumulative heat flow from reactor 2 over 20 days corresponds to the amount of heat used to generate steam over those 20 days. This is possible because the simulation does not account for any heat loss to the environment.

[0408] Comparison Example 1:

[0409] Comparative Example 1 shows the situation where thermal storage units 10 and 14 are absent. Figure 1 Steam is generated. Therefore, in this comparative example 1, energy from the batch reactor 2 cannot be stored. Thus, once the reactor is no longer operating and has cooled down, steam can no longer be generated.

Claims

1. A waste heat recovery system for generating steam for chemical industrial facilities, the waste heat recovery system comprising: • A chemical industrial facility that cannot operate continuously, the chemical industrial facility having at least one coolable reactor (2) connected to a primary loop, wherein, The at least one reactor (2) is designed such that during operation of the reactor (2), a reaction mixture occurs, and waste heat generated by the cooling of the reactor (2) flows through the primary circuit as a first heat transfer fluid in the form of a heated liquid or in the form of the reaction mixture itself, wherein the primary circuit fluidly connects the reactor (2) to a first heat exchanger (9) in such a way that the first heat transfer fluid is cooled in the first heat exchanger (9) and then returned to the reactor (2) to cool the reactor (2). • A secondary loop comprising a separate second heat transfer fluid coupled to the first heat exchanger (9) such that during operation of the at least one reactor (2), the second heat transfer fluid is heated by the first heat transfer fluid, and the secondary loop fluidly connects downstream of the first heat exchanger (9) a first heat storage unit (10), an evaporator unit (13) downstream of the first heat storage unit (10), a second heat storage unit (14) downstream of the evaporator unit (13), and the first heat exchanger (9) downstream of the second heat storage unit (14) to each other, thus completing the secondary loop. The evaporator unit (13) is designed such that steam is generated during the operation of the waste heat recovery system and is preferably supplied to at least one compressor (18).

2. The waste heat recovery system according to claim 1, wherein, The at least one reactor (2) has at least one cooling element, which preferably includes at least one integrated cooling coil, an integrated tube bundle, and / or a heat exchanger outside or inside the at least one reactor (2), and wherein the at least one cooling element is fluidly connected to the primary circuit and is configured such that the first heat transfer fluid passes through the at least one cooling element during operation of the industrial facility.

3. The waste heat recovery system according to claim 1 or 2, wherein, The second heat transfer fluid is water, and the evaporator unit (13) is a flash tank unit having an inlet for filling the flash tank with the second heat transfer fluid, an inlet for filling the flash tank with water, preferably demineralized water, an outlet for discharging water to the second heat storage unit (14), a steam outlet, and an expansion nozzle designed such that, during operation of the waste heat recovery system, expansion steam is generated as steam, and the steam is supplied to the at least one compressor (18) through the steam outlet.

4. The waste heat recovery system according to any one of the preceding claims, wherein, The evaporator unit (13) is a heat exchanger unit having an inlet and an outlet for the passage of the second heat transfer fluid, an inlet for the passage of water, and a steam outlet, wherein the heat exchanger unit is designed such that during operation of the waste heat recovery system, water in the heat exchanger unit evaporates and is fed to the at least one compressor (18) through the steam outlet.

5. A method for operating a waste heat recovery system for generating steam for a chemical industrial facility, said chemical industrial facility comprising... • A chemical industrial facility that cannot operate continuously, wherein the chemical industrial facility has at least one coolable reactor (2), wherein The at least one reactor (2) is designed such that during operation of the reactor (2), a reaction mixture occurs, and waste heat generated by the cooling of the reactor (2) flows through a primary loop as a first heat transfer fluid in the form of a heated liquid or in the form of the reaction mixture itself, wherein the primary loop fluidly connects the reactor (2) to a first heat exchanger (9) in such a way that the first heat transfer fluid is cooled in the first heat exchanger (9) and then returned to the reactor (2) to cool the reactor (2). • A secondary loop comprising a separate second heat transfer fluid and thermally coupled to the first heat exchanger (9) in such a manner that, during operation of the at least one reactor (2), the second heat transfer fluid is heated by the first heat transfer fluid, and The secondary loop fluidly connects the first heat exchanger (9) downstream of the first heat storage unit (10), the evaporator unit (13) downstream of the first heat storage unit (10), the second heat storage unit (14) downstream of the evaporator unit (13), and the first heat exchanger (9) downstream of the second heat storage unit (14) to each other, thus completing the secondary loop. The method includes the following steps when the at least one reactor (2) is running: • The reactants are fed into at least one of the reactors (2). • The reaction is carried out in at least one reactor (2). • The at least one reactor (2) is cooled by the first heat transfer fluid, which preferably flows through the first heat exchanger (9). • A portion of the heat from the first heat transfer fluid is transferred to the second heat transfer fluid via the first heat exchanger (9), wherein, The second heat transfer fluid at the inlet of the first heat exchanger (9) has a temperature in the range of 10°C to 1450°C and an absolute pressure in the range of 0.1 bar to 400 bar, and the second heat transfer fluid at the outlet of the first heat exchanger (9) has a temperature in the range of 30°C to 1500°C and an absolute pressure in the range of 0.1 bar to 400 bar. Furthermore, the first heat transfer fluid at the inlet of the first heat exchanger (9) has a temperature ranging from 35°C to 1500°C and an absolute pressure ranging from 0.1 bar to 400 bar, and the first heat transfer fluid at the outlet of the first heat exchanger (9) has a temperature ranging from 30°C to 1500°C and an absolute pressure ranging from 0.1 bar to 400 bar. • The heated second heat transfer fluid is fed into the first heat storage unit (10), wherein the second heat transfer fluid in the first heat storage unit (10) is at a temperature in the range of 30°C to 1500°C and an absolute pressure in the range of 0.1 bar to 400 bar. • The second heat transfer fluid is fed from the first heat storage unit (10) into the evaporator unit (13), wherein the flow rate of the second heat transfer fluid is determined based on both the heat flow rate transferred by the evaporator unit (13) and the fill level of the first heat storage unit (10), and is regulated by a first valve (12) located between the first heat storage unit (10) and the second heat storage unit (14) along the main flow direction. Furthermore, the temperature of the second heat transfer fluid at the inlet of the evaporator unit (13) is in the range of 30°C to 1500°C, and the absolute pressure at the inlet of the evaporator unit (13) is in the range of 0.1 bar to 400 bar. Furthermore, the temperature of the second heat transfer fluid at the outlet of the evaporator unit (13) is in the range of 10°C to 1450°C, and the absolute pressure at the outlet of the evaporator unit (13) is in the range of 0.1 bar to 400 bar. • Water(s) is fed into the evaporator unit (13) via a feed (p) outside the secondary loop, wherein the water(s) at the inlet of the evaporator unit (13) is at a temperature ranging from 5°C to 400°C and an absolute pressure ranging from 0.001 bar to 300 bar. • Steam is generated in the evaporator unit (13) by heat supplied from the second heat transfer fluid, wherein the steam at the steam outlet of the evaporator unit (13) is at a temperature ranging from 5°C to 373°C and an absolute pressure ranging from 0.001 bar to 220 bar. • Steam from the steam outlet of the evaporator unit (13) is fed to at least one compressor (18) via a conduit (q) outside the secondary circuit. The at least one compressor compresses the steam (r) to an absolute pressure in the range of 0.5 bar to 220 bar, and the temperature of the steam (r) at the outlet of the at least one compressor (18) is correspondingly in the range of 5°C to 373°C. • The second heat transfer fluid is fed from the evaporator unit (13) into the second heat storage unit (14), wherein the second heat transfer fluid in the second heat storage unit (14) is at a temperature ranging from 10°C to 1450°C and an absolute pressure ranging from 0.1 bar to 400 bar, and • The second heat transfer fluid is fed from the second heat storage unit (14) into the first heat exchanger (9). And in the case of multiple reactors, if one reactor (2) is not operating, or if no reactor is operating, the following steps are included: • The second heat transfer fluid is fed from the first heat storage unit (10) into the evaporator unit (13), wherein the flow rate of the second heat transfer fluid is determined based on both the heat flow rate transferred by the evaporator unit (13) and the fill level of the first heat storage unit (10), and is regulated by a first valve (12) located between the first heat storage unit (10) and the second heat storage unit (14) along the main flow direction, and the temperature of the second heat transfer fluid at the inlet of the evaporator unit (13) is in the range of 30°C to 1500°C, and the absolute pressure at the inlet of the evaporator unit (13) is in the range of 0.1 bar to 400 bar. • Water(s) is fed into the evaporator unit (13) via a feed (p) outside the secondary loop, wherein the water(s) at the inlet of the evaporator unit (13) is at a temperature ranging from 5°C to 400°C and an absolute pressure ranging from 0.001 bar to 300 bar. • Steam is generated in the evaporator unit (13) by heat supplied from the second heat transfer fluid, wherein the steam at the outlet of the evaporator unit (13) is at a temperature ranging from 5°C to 373°C and an absolute pressure ranging from 0.001 bar to 220 bar. • Steam from the evaporator unit (13) is fed into at least one compressor (18), which compresses the steam (r) to an absolute pressure in the range of 0.5 bar to 373 bar, and the temperature of the steam (r) at the outlet of the at least one compressor (18) is correspondingly in the range of 80°C to 220°C. • The second heat transfer fluid is fed from the evaporator unit (13) into the second heat storage unit (14), wherein the second heat transfer fluid in the second heat storage unit (14) is at a temperature ranging from 10°C to 1450°C and an absolute pressure ranging from 0.1 bar to 400 bar, and • The flow of the second heat transfer fluid between the second heat storage unit (14) and the first heat storage unit (10) along the main flow direction is blocked by cutting off the flow via a second valve (16) located between the second heat storage unit (14) and the first heat storage unit (10) along the main flow direction.

6. The method for operating a waste heat recovery system according to claim 5, wherein, The evaporator unit (13) is a heat exchanger unit, and the at least one compressor (18) is a mechanical steam compressor. The water at the inlet of the evaporator unit (13) is at a temperature in the range of 5°C to 400°C and an absolute pressure in the range of 0.001 bar to 300 bar. Furthermore, the steam (r) is compressed by the at least one compressor (18) to an absolute pressure in the range of 0.5 bar to 220 bar, and the temperature of the steam (r) at the outlet of the at least one compressor (18) is correspondingly in the range of 80°C to 373°C.

7. The method for operating a waste heat recovery system according to claim 5, wherein, The evaporator unit (13) is a flash tank unit, and the at least one compressor (18) is a mechanical steam compressor. The water at the inlet of the flash tank unit is at a temperature in the range of 5°C to 400°C and an absolute pressure in the range of 0.001 bar to 300 bar. Furthermore, the steam (r) is compressed by the at least one compressor (18) to an absolute pressure in the range of 0.5 bar to 220 bar, and the temperature of the steam (r) at the outlet of the at least one compressor (18) is correspondingly in the range of 80°C to 373°C.

8. The method of operating a waste heat recovery system according to any one of claims 5 to 7, wherein, The temperature of the second heat transfer fluid at the inlet of the first heat storage unit (10) is regulated by a first closed-loop temperature controller (TC, T3) with its associated temperature sensor (T3) located between the second heat storage unit (14, 10) along the main flow direction, in conjunction with a first closed-loop flow controller (FC, F1) with its associated flow sensor (F1), wherein the first closed-loop temperature controller (TC, T3) determines the difference between a predetermined setpoint value and the temperature of the second heat transfer fluid at the inlet of the first heat storage unit (10) detected by the first closed-loop temperature controller (TC, T3). Furthermore, the first closed-loop temperature controller (TC, T3) transmits the setpoint value to the first closed-loop flow controller (FC, F1) based on the determined difference, and the first closed-loop flow controller (FC, F1) adjusts the flow rate from the second thermal storage unit to the first thermal storage unit (14, 10) according to the setpoint value and the measured flow rate from the second thermal storage unit to the first thermal storage unit (14, 10).

9. The method of operating a waste heat recovery system according to any one of claims 5 to 8, wherein, The temperature of the second heat transfer fluid at the inlet of the second heat storage unit (14) is regulated by a second closed-loop temperature controller (TC, T4) with its associated temperature sensor (T4) in conjunction with a second closed-loop flow controller (FC, F3) with its associated flow sensor (F3) in the feed (p) of the evaporator unit (13). The second closed-loop temperature controller (TC, T4) determines the difference between a predetermined setpoint value and the temperature of the second heat transfer fluid at the inlet of the second heat storage unit (14) detected by the second closed-loop temperature controller (TC, T4), and The second closed-loop temperature controller (TC, T4) transmits the setpoint value to the second closed-loop flow controller (FC, F3) based on the determined difference, and the second closed-loop flow controller (FC, F3) adjusts the flow rate of the water (s) in the conduit (p) of the evaporator unit (13) through the valve (17) according to the setpoint value and the measured flow rate in the conduit (p) to the evaporator unit (13).

10. The method for operating a waste heat recovery system according to claim 9, wherein, The operating load of the at least one compressor (18) is adjusted to a value within the range of 30% to 100%, preferably 60% to 100%, of its maximum operating load, based on the valve position of the valve (17).

11. The method of operating a waste heat recovery system according to any one of claims 5 to 10, wherein, A first closed-loop fill level controller (LC, L1_1) with its associated fill level sensor (L1_1) serves as a higher-level closed-loop controller for the first thermal storage unit (10), and if the fill level sensor (L1_1) detects a value exceeding the defined maximum fill level of the first thermal storage unit (10), the valve 8 is throttled and the valve 6 is opened to cool at least some of the mass flow of the first heat transfer fluid in the conduit (d) in the process heat exchanger (7).

12. The method of operating a waste heat recovery system according to any one of claims 5 to 11, wherein, Closed-loop load controller (UC) with its associated sensors: Includes a flow sensor (F2) in the conduit (o) and / or the conduit (n), a temperature sensor (T4) in the conduit (o), and a temperature sensor (T1) for detecting the temperature in the first thermal storage unit (10). The difference in heat flow rate between the second heat transfer fluid in the conduit (o) and the second heat transfer fluid in the conduit (n) is detected, and this difference is used to calculate the difference between the measured heat flow rate difference and a defined load setpoint. The setpoint value based on the difference is delivered to the third closed-loop flow controller (FC, F2), which is a slave controller and has its associated flow sensor F2. Furthermore, the difference between the flow rate of the second heat transfer fluid in the conduit (o) or the conduit (n) to be calculated by the third closed-loop flow controller (FC, F2) and the setpoint value determined by the closed-loop load controller (UC) is used as the basis for the closed-loop control of the second-stage loop valve (12), which accordingly adjusts the flow rate of the second heat transfer fluid in the conduit (o).

13. The method for operating a waste heat recovery system according to claim 12, wherein, The defined load setpoint is determined by a second closed-loop fill level controller (LC, L1_2) having its associated fill level sensor (L1_2) within the first thermal storage unit (10), wherein the second closed-loop fill level controller (LC, L1_2) is a master controller and preferably a P controller, and wherein the second closed-loop fill level controller (LC, L1_2) calculates the difference between the fill level of the first thermal storage unit (10) and the defined setpoint value, and transmits the load setpoint to the closed-loop load controller (UC) based on the difference.

14. The method for operating a waste heat recovery system according to claim 13, wherein, The second closed-loop fill level controller (LC, L1_2) detects the continuous fill level value in the first thermal storage unit (10) and determines the load setpoint of the closed-loop load controller (UC) based on the detected fill level value, wherein the detected fill level value is limited to a range from a defined minimum fill level value to a defined maximum fill level value.

15. The method for operating a waste heat recovery system according to claim 13, wherein, The defined load setpoint is determined by the fill level sensor (L1_2), wherein the load setpoint can take only discrete values, and preferably can switch only between a first value corresponding to minimum steam production and a second value corresponding to maximum steam production.

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