A cascade utilization system based on steel sintering flue gas waste heat recovery

Abstract

This invention provides a cascade utilization system based on waste heat recovery from sintering flue gas in steelmaking, relating to the field of industrial waste heat recovery technology. It includes: a recovery module for recovering low-temperature flue gas waste heat from the third and fourth stages of a steelmaking sintering annular cooler via a flue gas-hot water heat exchanger, exchanging the heat from the low-temperature flue gas with closed-loop hot water to heat the water, and then sending the heated hot water into the evaporator and preheater of a low-temperature waste heat power generation unit; and an evaporation module for indirectly exchanging heat between a liquid organic working fluid and the supplied hot water within the evaporator and preheater, absorbing the heat energy from the hot water to obtain slightly superheated high-pressure organic working fluid steam, and then introducing the high-pressure organic working fluid steam into a turbine to drive the turbine impeller to rotate and perform work. This invention improves the overall heat recovery efficiency and system operational stability.

Description

Technical Field

[0001] This invention relates to the field of industrial waste heat recovery technology, and in particular to a cascade utilization system based on waste heat recovery from steel sintering flue gas. Background Technology

[0002] In the steel sintering production process, the annular cooler is the core equipment for cooling sinter. The medium and low temperature flue gas emitted from its third and fourth stages carries a large amount of sensible heat, accounting for a considerable proportion of the total sensible heat of the sinter. It is a waste heat resource with great potential for recovery. Currently, the industry generally adopts a combination system of flue gas hot water heat exchanger and ORC low temperature generator set to recover part of the waste heat. The specific process is to transfer the heat in the flue gas to the closed-loop hot water through the heat exchanger, and then the hot water heats the organic working fluid, which finally drives the turbine to generate electricity.

[0003] A steel company introduced this type of waste heat recovery system during the energy-saving renovation of its sintering production line. A flue gas hot water heat exchanger was deployed in the rear section of the annular cooler to convert the heat in the low-temperature flue gas into electrical energy, thereby reducing the overall energy consumption of the sintering process. However, after actual operation, specific defects emerged: an unavoidable relative movement gap exists between the annular cooler trolley and the flue gas recovery hood, and the existing sealing structure is difficult to adapt to the deformation of the equipment under high-temperature conditions. This causes a large amount of ambient-temperature cold air to seep into the flue gas system through the gap. After mixing with the cold air, the temperature of the flue gas entering the heat exchanger drops significantly, directly resulting in insufficient hot water heating efficiency. This fails to meet the ORC unit's requirements for the evaporation temperature of the organic working fluid, ultimately preventing the full extraction of waste heat from the low-temperature flue gas. The overall heat recovery effect is far below the initial design expectations. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a cascade utilization system based on waste heat recovery of sintering flue gas in steelmaking, thereby improving the overall heat recovery efficiency and system operation stability.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0006] In a first aspect, a cascade utilization system based on waste heat recovery from steel sintering flue gas is provided, the method comprising:

[0007] The recovery module is used to recover the waste heat of the low-temperature flue gas in the third and fourth stages of the steel sintering ring cooler through the flue gas and hot water heat exchanger. It exchanges the heat of the low-temperature flue gas with the closed-loop hot water, so that the hot water is heated, and then sends the heated hot water into the evaporator and preheater of the low-temperature waste heat power generation unit.

[0008] The evaporation module is used to indirectly exchange heat between the liquid organic working fluid and the supplied hot water in the evaporator and preheater, absorb the heat energy in the hot water, obtain slightly superheated high-pressure organic working fluid steam, and introduce the high-pressure organic working fluid steam into the turbine to drive the turbine impeller to rotate and do work.

[0009] The condensation module is used to generate low-pressure organic working fluid vapor by rotating the turbine impeller and connecting to the generator to generate electricity. The organic working fluid vapor is then introduced into the condenser, where the cooling water in the condenser releases heat, causing the condensate to be reduced to liquid organic working fluid.

[0010] The pressurization module is used to pressurize the condensed liquid organic working fluid through the organic working fluid pump and send it back to the preheater and evaporator to re-participate in the heat exchange cycle;

[0011] The circulation module is used to send the cooled hot water back to the flue gas and hot water heat exchanger to reabsorb the waste heat of the flue gas based on the heat exchange cycle. The circulating cooling water pump draws water from the cold water pool, pressurizes it and sends it to the condenser. After absorbing heat in the condenser, the cooling water is cooled by the cooling tower and returned to the cold water pool, thus obtaining the respective circulation loops of hot water and cooling water.

[0012] Furthermore, the waste heat from the low-temperature flue gas in the third and fourth stages of the steel sintering ring cooler is recovered through a flue gas-hot water heat exchanger. This heat is then transferred to the closed-loop hot water system, heating the water, which is then fed into the evaporator and preheater of the low-temperature waste heat power generation unit. This process includes:

[0013] The return water after cooling by the low-temperature waste heat power generation unit is diverted and sent to the first hot water heater installed in the dust removal pipeline at the tail of the sintering machine and the second hot water heater installed at the material discharge dust removal position of the annular cooler. The return water is initially heated by the waste heat of the dust removal flue gas at the location to obtain the first stage of heated hot water.

[0014] The first-stage heated hot water is collected and sent to the third hot water heater located in the middle and rear section of the annular cooler. Driven by the annular cooler blower, the waste heat of the third-stage flue gas after penetrating the material layer of the annular cooler is used to deeply heat the first-stage heated hot water to obtain the second-stage heated hot water.

[0015] The second-stage heated water is sent to the fourth hot water heater located in the fourth section of the annular cooler. Driven by a low-temperature circulating fan, the closed-loop circulating flue gas formed after penetrating the material layer provides the final heating for the second-stage heated water, bringing it to the preset design temperature.

[0016] Hot water that has reached the design temperature is uniformly transported to the evaporator and preheater of the low-temperature waste heat power generation unit to transfer the heat energy of the hot water to the organic working fluid.

[0017] Furthermore, within the evaporator and preheater, the liquid organic working fluid undergoes indirect heat exchange with the supplied hot water, absorbing the heat energy from the hot water to obtain slightly superheated high-pressure organic working fluid steam. This high-pressure organic working fluid steam is then introduced into the turbine, driving the turbine impeller to rotate and perform work, including:

[0018] The low-temperature, low-pressure liquid organic working fluid in the condenser is pressurized by an organic working fluid pump to obtain a high-pressure liquid organic working fluid.

[0019] The high-pressure liquid organic working fluid is sent to the preheater and the evaporator to exchange heat indirectly with the cooled hot water, absorbing sensible heat, so that the high-pressure liquid organic working fluid is initially heated to a near-saturated liquid state.

[0020] The pre-heated high-pressure liquid organic working fluid is sent to the evaporator to exchange heat indirectly with the high-temperature hot water in the flue gas and hot water heat exchanger, absorbing heat energy, so that the working fluid is further heated until it is completely evaporated and becomes slightly superheated high-pressure organic working fluid steam.

[0021] Slightly superheated high-pressure organic working fluid steam is introduced into the turbine, so that the pressure energy of the organic working fluid steam is converted into mechanical energy, which drives the turbine impeller to rotate and do work.

[0022] Furthermore, the turbine impeller rotates to generate power, which in turn generates electricity through a connected generator, producing low-pressure organic working fluid vapor. This vapor is then introduced into a condenser, where cooling water releases heat, reducing the condensate back to liquid organic working fluid. This process includes:

[0023] The low-pressure organic working fluid vapor, after being expanded and worked by the turbine, is introduced into the condenser;

[0024] Based on the low-pressure organic working fluid vapor in the condenser, it indirectly exchanges heat with the cooling water, releases the latent heat of vaporization to the cooling water, and cools the low-pressure organic working fluid vapor and transforms it into a saturated liquid working fluid.

[0025] By subjecting a saturated liquid working fluid to subcooling, the temperature of the liquid working fluid is lowered, resulting in a low-temperature, low-pressure liquid organic working fluid with subcooling.

[0026] Furthermore, the condensed liquid organic working fluid is pressurized by an organic working fluid pump and sent back to the preheater and evaporator to re-participate in the heat exchange cycle, including:

[0027] The liquid organic working fluid that has undergone phase change condensation is received, and the liquid organic working fluid is pressurized by an organic working fluid pump to increase the pressure of the liquid organic working fluid to a preset working pressure value, so as to obtain pressurized liquid organic working fluid.

[0028] The pressurized liquid organic working fluid is transported to the preheater, where it is initially heated by medium-temperature flue gas to obtain preheated organic working fluid.

[0029] The preheated organic working medium is then fed to the evaporator, where it is heated by the high-temperature flue gas, causing it to change phase to saturated or superheated steam, thus completing the regeneration process of the working medium.

[0030] The regenerated organic working fluid steam is reintroduced into the generator set to start a new heat exchange cycle.

[0031] Furthermore, the preheated organic working fluid is continued to be fed to the evaporator, where it is heated by high-temperature flue gas, causing it to transform into a saturated or superheated steam state, thus completing the regeneration process of the working fluid, including:

[0032] The preheated organic working fluid output after being heated by the preheater is obtained, and the preheated organic working fluid is transported to the working fluid inlet of the evaporator to obtain the working fluid to be heated;

[0033] The working fluid to be heated is monitored to confirm that it meets the inlet operating conditions of the evaporator.

[0034] The working fluid that meets the operating conditions can indirectly exchange heat with the high-temperature flue gas in the evaporator and absorb the heat energy of the high-temperature flue gas.

[0035] The heat exchange process is controlled to cause the working fluid to undergo a phase change process from liquid to gas, resulting in organic working fluid vapor with a preset superheat.

[0036] Organic working fluid steam is output from the steam outlet of the evaporator to obtain regenerated working fluid steam.

[0037] Furthermore, based on the heat exchange cycle, the cooled hot water is returned to the flue gas and hot water heat exchanger via a hot water circulation pump to reabsorb the waste heat from the flue gas, including:

[0038] The cooled hot water returned from the heating system is obtained, and the cooled hot water is pressurized to reach the preset circulation pressure to obtain pressurized hot water.

[0039] The pressurized hot water is delivered to the inlet of the flue gas and hot water heat exchanger, so that the pressurized hot water delivered to the heat exchanger exchanges heat with the medium and low temperature flue gas in a countercurrent manner, absorbing the waste heat in the flue gas and raising its temperature to obtain heated hot water.

[0040] The heated water is drawn out from the outlet of the flue gas and hot water heat exchanger and then transported back to the heating water supply, thus completing the recycling of hot water.

[0041] Furthermore, water is drawn from the cold water pool and pressurized by a circulating cooling water pump and transported to the condenser. After absorbing heat in the condenser, the cooling water is cooled by a cooling tower and returned to the cold water pool, resulting in separate circulation loops for hot water and cooling water, including:

[0042] Cooling water to be used is obtained from the cold water pool and pressurized to reach the inlet pressure required by the condenser, thus obtaining pressurized cooling water.

[0043] Pressurized cooling water is delivered to the cooling water inlet of the condenser, so that the pressurized cooling water delivered to the condenser can exchange heat indirectly with the organic working fluid vapor, absorb the latent heat of condensation of the organic working fluid and rise in temperature, and obtain heated cooling water.

[0044] The heated cooling water is transported to the cooling tower for heat dissipation and cooling down, so that the temperature of the cooling water drops to the preset range. The cooled cooling water is then returned to the cold water pool, completing the cooling water circulation loop.

[0045] In a second aspect, a computing device includes:

[0046] One or more processors;

[0047] A storage device for storing one or more programs that, when executed by one or more processors, cause the one or more processors to implement the method.

[0048] Thirdly, a computer-readable storage medium storing a program that, when executed by a processor, implements the method.

[0049] The above-described solution of the present invention has at least the following beneficial effects:

[0050] This system employs multi-dimensional technologies. The recovery module utilizes the dust removal pipes at the tail of the sintering machine, the dust removal position at the material discharge point of the annular cooler, and the multi-position heaters in the third and fourth sections of the annular cooler to achieve a stepped temperature increase from initial heating of hot water diversion to deep heating of the confluence and finally heating of the closed-loop flue gas. The evaporation module adopts a step-by-step heat exchange process of pressurization of organic working fluid to preliminary heating of the preheater and deep evaporation of the evaporator. The condensation module adds working fluid subcooling treatment. The circulation module constructs a dual closed-loop system of closed-loop pressurized circulation of hot water and independent open circulation of cooling water. Therefore, it effectively overcomes the technical problems of insufficient recovery of low-temperature flue gas waste heat due to a single heat exchange point in the existing system, the inconsistency of organic working fluid heating making it difficult to form slightly superheated steam, and the impact of medium circulation pressure fluctuations on the stable operation of the ORC system. As a result, it achieves precise step-by-step recovery of low-temperature flue gas waste heat, efficient heat exchange matching between organic working fluid and heat source to improve turbine working efficiency, and the dual closed-loop circulation ensures stable operation of the system even during fluctuations in sintering production, ultimately improving the overall waste heat utilization efficiency and power generation reliability. Attached Figure Description

[0051] Figure 1 This is a schematic diagram of a cascade utilization system based on waste heat recovery from steel sintering flue gas, provided by an embodiment of the present invention.

[0052] Figure 2 This is a schematic diagram of a cascade utilization system for waste heat recovery from sintering flue gas provided by an embodiment of the present invention. The system uses an organic working fluid pump to pressurize the condensed liquid organic working fluid and send it back to the preheater and evaporator to re-participate in the heat exchange cycle. Detailed Implementation

[0053] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0054] like Figure 1 As shown, an embodiment of the present invention proposes a cascade utilization system based on waste heat recovery from steel sintering flue gas, comprising the following steps:

[0055] The recovery module is used to recover the waste heat of the low-temperature flue gas in the third and fourth stages of the steel sintering ring cooler through the flue gas and hot water heat exchanger. It exchanges the heat of the low-temperature flue gas with the closed-loop hot water, so that the hot water is heated, and then sends the heated hot water into the evaporator and preheater of the low-temperature waste heat power generation unit.

[0056] The evaporation module is used to indirectly exchange heat between the liquid organic working fluid and the supplied hot water in the evaporator and preheater, absorb the heat energy in the hot water, obtain slightly superheated high-pressure organic working fluid steam, and introduce the high-pressure organic working fluid steam into the turbine to drive the turbine impeller to rotate and do work.

[0057] The condensation module is used to generate low-pressure organic working fluid vapor by rotating the turbine impeller and connecting to the generator to generate electricity. The organic working fluid vapor is then introduced into the condenser, where the cooling water in the condenser releases heat, causing the condensate to be reduced to liquid organic working fluid.

[0058] The pressurization module is used to pressurize the condensed liquid organic working fluid through the organic working fluid pump and send it back to the preheater and evaporator to re-participate in the heat exchange cycle;

[0059] The circulation module is used to send the cooled hot water back to the flue gas and hot water heat exchanger to reabsorb the waste heat of the flue gas based on the heat exchange cycle. The circulating cooling water pump draws water from the cold water pool, pressurizes it and sends it to the condenser. After absorbing heat in the condenser, the cooling water is cooled by the cooling tower and returned to the cold water pool, thus obtaining the respective circulation loops of hot water and cooling water.

[0060] In this embodiment of the invention, the system employs a recovery module for recovering waste heat from the third and fourth stages of the circulatory cooler using a flue gas hot water heat exchanger and a closed-loop hot water transport module; an evaporation module for generating slightly superheated high-pressure steam through indirect heat exchange between the organic working fluid and hot water; a condensation module for condensing the organic working fluid steam with cooling water assistance; a pressurization module for pressurizing the working fluid and refluxing it using an organic working fluid pump; and a circulation module for closed-loop circulation of hot water and cooling water. This constructs a complete waste heat recovery, heat exchange, power generation, and medium circulation system. Therefore, it overcomes the technical problems in existing technologies where the waste heat from the third and fourth stages of the circulatory cooler in steel sintering is not fully recovered, the organic working fluid cannot be stably circulated for heat exchange leading to low thermal efficiency, and the lack of closed-loop medium circulation causes energy waste. This achieves efficient extraction and cascade utilization of waste heat from the low-temperature flue gas, ensures stable heat exchange between the organic working fluid and hot water / cooling water, improves the overall thermal efficiency and operational reliability of the system, and reduces energy consumption, thus contributing to energy saving and consumption reduction in the sintering process.

[0061] In a preferred embodiment of the present invention, the waste heat of the low-temperature flue gas from the third and fourth stages of the steel sintering ring cooler is recovered through a flue gas-hot water heat exchanger. The heat of the low-temperature flue gas is exchanged with the closed-loop hot water, thereby heating the hot water. The heated hot water is then sent to the evaporator and preheater of the low-temperature waste heat power generation unit, comprising:

[0062] The return water cooled by the low-temperature waste heat power generation unit is diverted and sent to the first hot water heater located in the dust removal duct at the tail of the sintering machine and the second hot water heater located at the dust removal position of the annular cooler. The return water is initially heated by the waste heat of the dust removal flue gas at these locations to obtain the first-stage heated hot water. Specifically, this involves: obtaining the return water whose temperature has decreased after heat transfer in the low-temperature waste heat power generation unit. This part of the return water is the water flow whose temperature has decreased after passing through the evaporator and preheater. This part of the cooled return water is divided into two independent water flows. The first water flow is sent to the first hot water heater located in the dust removal duct at the tail of the sintering machine, and the second water flow is sent to the second hot water heater located at the dust removal position of the annular cooler. The dust removal flue gas flowing in the dust removal duct at the tail of the sintering machine carries a certain amount of waste heat, and the dust removal flue gas at the dust removal position of the annular cooler also contains waste heat. The waste heat carried by the dust removal flue gas at these two locations is used to heat the return water entering the first hot water heater and the second hot water heater, respectively. After being heated by the residual heat of the flue gas from these two dust removal locations, the originally low-temperature return water is initially heated, eventually forming the first-stage heated hot water with a slightly improved temperature.

[0063] The first-stage heated water is collected and sent to the third hot water heater located in the middle and rear section of the annular cooler. Driven by the annular cooler blower, the waste heat of the third-stage flue gas penetrating the material layer of the annular cooler is used to further heat the first-stage heated water to obtain the second-stage heated water. Specifically, the first-stage heated water, which has been heated in the first hot water heater, and the first-stage heated water, which has been heated in the second hot water heater, are collected in the same pipe to form a concentrated flow of first-stage heated water. This concentrated flow of first-stage heated water is then transported through a conveying pipe to the third hot water heater located in the middle and rear section of the annular cooler. The annular cooler blower is started, and under its driving force, outside air penetrates the sintered ore layer in the annular cooler and exchanges heat with the sintered ore to form third-stage flue gas carrying waste heat. This third-stage flue gas flows through the third hot water heater, and the waste heat carried by the third-stage flue gas further heats the first-stage heated water entering the third hot water heater. By deeply absorbing the heat of the third-stage flue gas, the temperature of the first-stage heated water is increased, ultimately yielding the second-stage heated water.

[0064] The second-stage heated water is fed into the fourth hot water heater located in the fourth section of the annular cooler. Driven by a low-temperature circulating fan, the closed-loop circulating flue gas formed after penetrating the material layer provides the final heating for the second-stage heated water, bringing it to the preset design temperature. Specifically, the second-stage heated water, heated by the third hot water heater, is transported through a dedicated pipeline to the fourth hot water heater in the fourth section of the annular cooler. The low-temperature circulating fan is then activated, driving the airflow through the sintered ore layer in the fourth section of the annular cooler. This airflow does not directly discharge to the outside but forms a closed-loop circulating airflow, i.e., closed-loop circulating flue gas. This closed-loop circulating flue gas can continuously retain its own residual heat and effectively reduce the mixing of ambient cold air. The residual heat carried by this closed-loop circulating flue gas provides the final heating for the second-stage heated water entering the fourth hot water heater. Under the continuous heating of the residual heat from the closed-loop circulating flue gas, the temperature of the second-stage heated water continuously rises until it reaches the preset design temperature, meeting the temperature requirements for heat exchange of the organic working fluid.

[0065] Hot water that has reached the design temperature is uniformly transported to the evaporator and preheater of the low-temperature waste heat power generation unit to transfer the heat energy of the hot water to the organic working fluid. Specifically, this includes: collecting hot water that has completed final heating in the fourth hot water heater and whose temperature has reached the preset design temperature, ensuring that all second-stage heated hot water entering the fourth hot water heater has reached the design temperature standard, and transporting this hot water that has reached the design temperature to the evaporator and preheater of the low-temperature waste heat power generation unit through a unified hot water transport pipeline. When the hot water that has reached the design temperature enters the evaporator and preheater, the hot water will indirectly exchange heat with the liquid organic working fluid stored in the evaporator and preheater. The hot water transfers its own heat energy to the liquid organic working fluid, providing the necessary heat for the subsequent evaporation and heating of the liquid organic working fluid, so as to meet the requirements of the ORC unit for the evaporation temperature of the organic working fluid.

[0066] In this embodiment of the invention, a multi-source waste heat recovery technology is adopted. The return water from the low-temperature waste heat power generation unit is first diverted to the first hot water heater in the dust removal pipeline at the tail of the sintering machine and the second hot water heater at the material discharge and dust removal position of the annular cooler to preheat it with the waste heat of the dust removal flue gas. Then, it is converged to the third hot water heater in the middle and rear section of the annular cooler to be deeply heated by the waste heat of the three-stage flue gas driven by the annular cooler blower. Finally, it is sent to the fourth hot water heater in the fourth section of the annular cooler to be finally heated by the closed-loop flue gas driven by the low-temperature circulating fan. This staged multi-source waste heat recovery technology overcomes the technical problem that the flue gas temperature drops and the hot water heating efficiency is insufficient due to the infiltration of room temperature cold air between the annular cooler trolley and the flue gas recovery hood. As a result, it is unable to meet the evaporation temperature requirements of the ORC low-temperature waste heat power generation unit for the organic working medium. Ultimately, the hot water stably reaches the preset design temperature, ensuring that sufficient heat energy can be transferred to the organic working medium. This improves the waste heat recovery utilization rate of the low-temperature flue gas in the third and fourth sections of the steel sintering annular cooler and the system operation stability.

[0067] In a preferred embodiment of the present invention, within the evaporator and preheater, the liquid organic working fluid undergoes indirect heat exchange with the supplied hot water, absorbing the heat energy from the hot water to obtain slightly superheated high-pressure organic working fluid steam. This high-pressure organic working fluid steam is then introduced into a turbine to drive the turbine impeller to rotate and perform work. The process includes:

[0068] The low-temperature, low-pressure liquid organic working fluid in the condenser is pressurized by an organic working fluid pump to obtain a high-pressure liquid organic working fluid. Specifically, this involves: obtaining the low-temperature, low-pressure liquid organic working fluid from the condenser after cooling treatment; this organic working fluid was formed by heat exchange and condensation with cooling water in the condenser after the turbine performed work. Then, the organic working fluid pump is started, sending this low-temperature, low-pressure liquid organic working fluid into the pump's inlet. Through the mechanical pressurization action of the pump, the pressure of the liquid organic working fluid is gradually increased, transforming the originally low-pressure liquid organic working fluid into a high-pressure liquid organic working fluid that meets the subsequent heat exchange requirements, thus completing the pressurization process.

[0069] High-pressure liquid organic working fluid is indirectly heated in the preheater and evaporator by exchanging heat with the cooled hot water, absorbing sensible heat to initially heat the high-pressure liquid organic working fluid to near-saturation. Specifically, this involves: pressurizing the high-pressure liquid organic working fluid via an organic working fluid pump and transporting it to the preheater working fluid inlet through a dedicated pipeline; simultaneously, cooling hot water from the evaporator of the low-temperature waste heat power generation unit is transported to the preheater hot water inlet. An ant colony optimization algorithm is simultaneously activated. The core logic of the ant colony optimization algorithm simulates the process of an ant colony collaboratively finding the optimal path. The combination of working fluid flow rate and hot water flow rate is considered the optimal path. The goal is to rapidly heat the working fluid to near-saturation and stabilize the heat exchange temperature difference. The algorithm finds the optimal flow ratio through colony iteration, avoiding uneven heat exchange or heat waste caused by a single flow rate setting. First, the ant colony is initialized: each ant represents a flow ratio combination, the colony size is set to 15-20 groups, and the flow range is limited to the safe operating range of the preheater. The algorithm imports high-quality cases from historical heat exchange data as initial optimization reference pheromones. When the indirect heat exchanger is started, the algorithm enters the dynamic optimization phase: the flow ratios corresponding to each ant are tested synchronously. Temperature sensors collect real-time data on the working fluid outlet temperature and the temperature difference between the hot water inlet and outlet, which are fed back to the algorithm as path scores. Flow ratios with working fluid temperatures close to saturated liquid and small temperature fluctuations are marked as high-scoring, and the algorithm increases their pheromone concentration; conversely, it decreases the pheromone concentration. In the next iteration, the ants will prioritize flow ratios with high pheromone concentrations, while retaining a small amount of random exploration. For example, if a certain flow ratio has the highest score, the ants will fine-tune around that ratio for continuous optimization. When the working fluid outlet temperature deviation of the optimal flow ratio is less than or equal to ±2℃ and the temperature difference fluctuation is ≤±1℃ in three consecutive iterations, the algorithm determines that optimization is complete and locks the ratio as a stable operating parameter. During subsequent heat exchange, the algorithm continuously monitors the data: if the working fluid temperature deviates from the target range, or the hot water temperature fluctuates due to changes in waste heat supply, the algorithm will quickly adjust the flow ratio to ensure that the high-pressure liquid organic working fluid always efficiently absorbs the sensible heat of the hot water and gradually heats up to near saturated liquid.

[0070] Step 2.2 involves sending the preheated high-pressure liquid organic working fluid into the evaporator for indirect heat exchange with the high-temperature hot water in the flue gas and hot water heat exchanger. This process absorbs heat energy, allowing the working fluid to be further heated until it is completely evaporated and becomes slightly superheated high-pressure organic working fluid steam. Specifically, this includes: transporting the preheated high-pressure organic working fluid, which is in a near-saturated liquid state in the preheater, to the working fluid inlet of the evaporator via a pipeline; and transporting the high-temperature hot water, formed after absorbing the waste heat from the low-temperature flue gas in the third and fourth stages of the annular cooler, to the hot water inlet of the evaporator. Inside the evaporator, the near-saturated liquid high-pressure organic working fluid and the high-temperature hot water exchange indirectly through heat exchange elements. The high-temperature hot water releases a large amount of heat energy, which is transferred to the organic working fluid. The organic working fluid first absorbs heat energy to complete the complete evaporation from liquid to gas, forming saturated steam. It then continues to absorb heat energy, further increasing the steam temperature, ultimately transforming it into slightly superheated high-pressure organic working fluid steam, ensuring that the steam quality meets the turbine's operating requirements.

[0071] Slightly superheated, high-pressure organic working fluid steam is introduced into a turbine, converting the pressure energy of the organic working fluid steam into mechanical energy, which drives the turbine impeller to rotate and do work. Specifically, the slightly superheated, high-pressure organic working fluid steam generated in the evaporator is guided to the steam inlet of the turbine through a steam delivery pipeline, allowing the steam to enter the flow passage of the turbine smoothly. The slightly superheated, high-pressure organic working fluid steam expands and does work inside the turbine, and its own pressure energy is gradually converted into mechanical energy that drives the turbine impeller to rotate. Under the continuous action of pressure energy, the turbine impeller rotates at a stable speed, providing the necessary power to drive the generator to generate electricity.

[0072] In this embodiment of the invention, a step-by-step processing technique of pressurizing, staged heat exchange, and energy conversion is adopted. This technique involves first pressurizing the low-temperature, low-pressure liquid organic working fluid in the condenser into a high-pressure liquid organic working fluid via an organic working fluid pump, then sending it to the preheater for indirect heat exchange with the cooled hot water in the evaporator to absorb sensible heat to near saturation liquid state, and then sending it to the evaporator for indirect heat exchange with the high-temperature hot water in the flue gas-hot water heat exchanger until it is completely evaporated and becomes slightly superheated high-pressure organic working fluid steam. Finally, the steam is introduced into the turbine to realize the conversion of pressure energy into mechanical energy. This technique effectively overcomes the technical problem that the low-temperature, low-pressure liquid organic working fluid directly enters the heat exchange ring and cannot drive the turbine to work efficiently. This allows the organic working fluid to fully absorb heat energy at different temperatures and form high-quality slightly superheated steam. This not only avoids the erosion problem of turbine blades due to insufficient working fluid dryness, but also efficiently converts pressure energy into mechanical energy to drive the turbine impeller rotation, improving the energy conversion efficiency and operational stability of the ORC low-temperature waste heat power generation unit.

[0073] In a preferred embodiment of the present invention, low-pressure organic working fluid vapor is obtained by the rotation of a turbine impeller to perform work and the rotation of a connected generator to generate electricity. The organic working fluid vapor is then introduced into a condenser, where the cooling water in the condenser releases heat, reducing the condensate to liquid organic working fluid. This includes:

[0074] The low-pressure organic working fluid steam, after being expanded and worked by the turbine, is introduced into the condenser. Specifically, this involves collecting the organic working fluid steam after it has been expanded and worked by the turbine. At this point, the steam has consumed a large amount of pressure energy due to driving the turbine impeller, and its pressure has dropped to the low-pressure range of the ORC system cycle. Its temperature has also dropped with the pressure to near the saturation temperature at the corresponding low pressure, placing it in a low-pressure gaseous state. A small amount of residual heat energy may remain in the steam. The shut-off valve and regulating valve on the dedicated steam delivery pipeline connecting the turbine outlet and the condenser inlet are opened. The flow rate of the low-pressure organic working fluid steam is controlled by adjusting the flow regulating valve on the pipeline, ensuring that the steam enters the steam inlet chamber of the condenser at a stable flow rate. After entering the chamber, the steam is evenly distributed to the outer space of the heat exchange tube bundle by the distributor inside the condenser, ensuring that the steam makes full contact with each heat exchange tube.

[0075] Based on the low-pressure organic working fluid vapor in the condenser, it indirectly exchanges heat with the cooling water, releasing the latent heat of vaporization to the cooling water, so that the low-pressure organic working fluid vapor is cooled and phase-changes into a saturated liquid working fluid. Specifically, it includes: when the low-pressure organic working fluid vapor enters the heat exchange area of ​​the condenser, the circulating cooling water system is started: first, the circulating cooling water pump draws cooling water that has been cooled by the cooling tower from the cold water pool, and pressurizes the cooling water to 0.4 to 0.6 MPa, and then delivers it to the tube inlet of the condenser through the cooling water inlet pipe. The condenser adopts a shell-and-tube heat exchange structure, in which low-pressure organic working fluid vapor flows in the shell side and cooling water flows in the tube side. To improve heat exchange efficiency, baffles are installed in the shell side, forcing the vapor to constantly change direction during flow, forming a turbulent state, increasing the contact area and contact time between the vapor and the heat exchange tube wall. At the same time, the cooling water in the tube side also flows in a turbulent form, enhancing heat transfer. During the heat exchange process, the low-pressure organic working fluid vapor continuously releases latent heat of vaporization to the cooling water in the tube side. As the latent heat is gradually released, the vapor temperature gradually decreases to the saturation temperature at the corresponding pressure, and then begins to condense into tiny droplets on the surface of the heat exchange tube wall. The droplets continuously gather and grow larger, and finally drip down the tube wall under the action of gravity, forming a saturated liquid working fluid, thus initially completing the phase change from gas to liquid.

[0076] The saturated liquid working fluid is subcooled to lower its temperature, resulting in a low-temperature, low-pressure liquid organic working fluid with subcooling. Specifically, when the saturated liquid working fluid drips from the heat exchange tube bundle to the bottom of the condenser, it enters a specially designed subcooling section. Within this section, the saturated liquid working fluid undergoes secondary indirect heat exchange with the cooling coils. At this point, the temperature of the liquid working fluid further decreases from its saturation temperature at the corresponding pressure, typically controlled to be 5-10°C lower than the saturation temperature, thus achieving subcooling. During the subcooling process, the temperature of the liquid working fluid is monitored in real-time using a temperature sensor at the bottom of the condenser. If the temperature does not reach the preset subcooling degree, the cooling water flow rate of the cooling coils in the subcooling section is adjusted to ensure the working fluid temperature stably drops to the target value, ultimately forming a low-temperature, low-pressure liquid organic working fluid with the preset subcooling degree. Finally, these low-temperature, low-pressure liquid organic working fluids continue to collect downwards under the influence of gravity, flowing into the liquid accumulation chamber at the bottom of the condenser, completing the entire condensation, subcooling, and collection process, and providing a stable and qualified liquid working fluid for the organic working fluid pump in the next cycle.

[0077] In this embodiment of the invention, a low-pressure organic working fluid vapor produced by the turbine expansion is introduced into the condenser. It first releases its latent heat of vaporization and transforms into a saturated liquid working fluid through indirect heat exchange with cooling water. Then, the saturated liquid working fluid undergoes subcooling treatment. This integrated working fluid condensation-subcooling technology effectively overcomes the technical problems of incomplete condensation of the low-pressure organic working fluid vapor, high saturated liquid working fluid temperature leading to cavitation when the subsequent organic working fluid pump is drawn in, and insufficient release of residual heat energy in the working fluid circulation affecting system thermal efficiency. This allows the organic working fluid to be fully converted into a low-temperature, low-pressure liquid with subcooling and collect at the bottom of the condenser. This avoids damage to the organic working fluid and pump due to cavitation, ensuring the continuous stability of the working fluid circulation. Furthermore, by fully releasing the residual heat energy of the working fluid, energy loss is reduced, improving the overall heat recovery efficiency of the ORC low-temperature waste heat power generation system.

[0078] like Figure 2 As shown, in another preferred embodiment of the present invention, the condensed liquid organic working fluid is pressurized by an organic working fluid pump and sent back to the preheater and evaporator to re-participate in the heat exchange cycle, including:

[0079] The system receives liquid organic working fluid that has undergone phase change condensation. An organic working fluid pump pressurizes the fluid to a preset working pressure, resulting in pressurized liquid organic working fluid. Specifically, this involves opening the valve connecting the liquid accumulation chamber at the bottom of the condenser to the inlet of the organic working fluid pump. The low-temperature, low-pressure liquid organic working fluid, with subcooling, flows into the pump inlet chamber by gravity. A level sensor monitors the liquid level in real time, and once the preset height is reached, the organic working fluid pump and the RMSProp algorithm are simultaneously activated. The core logic of the RMSProp algorithm is to dynamically adjust the control parameter, i.e., the impeller speed, by accumulating the average squared decay of historical pressure deviations. This allows the speed adjustment to better match the pressure change pattern, avoiding both overshoot due to excessively rapid pressurization and pressure lag due to excessively slow adjustment. After the algorithm starts, it first initializes the core parameters: using a preset working pressure value as the target value, the target pressure is adapted to the organic working fluid type and system design; setting an initial impeller speed range, which meets the safe operation requirements of the organic working fluid pump; simultaneously setting a deviation decay coefficient, which is used to balance the influence weights of recent and long-term pressure deviations; and controlling the pressure deviation within a reasonable range. With the optimization objective set as the speed adjustment within the reasonable range and without drastic fluctuations, the impeller inside the organic working fluid pump begins to rotate and pressurize. Simultaneously, the RMSProp algorithm enters the dynamic adjustment stage: the pressure sensor collects the instantaneous pressure data at the pump outlet in real time, the algorithm calculates the deviation between the current pressure and the target value, and continuously accumulates the average squared decay of this deviation. At the same time, it tracks the overall trend of recent pressure deviation. If the recent deviation remains at a high level, it indicates that the current speed adjustment is insufficient, and the algorithm will amplify the adjustment range of the next speed adjustment; if the recent deviation gradually narrows, it indicates that the speed adjustment is becoming reasonable, and the algorithm will reduce the adjustment range to avoid pressure overshoot due to large adjustments.

[0080] Throughout the pressurization process, the algorithm dynamically adapts the speed adjustment rhythm based on the historical average of the squared deviation decay. When the working fluid flow rate changes slightly due to changes in operating conditions, the pressure will fluctuate slightly. The RMSProp algorithm responds quickly, judging whether the fluctuation is a random deviation or a trend change based on historical data. If it is a random deviation, i.e., the instantaneous deviation quickly falls back after it appears, the current speed is maintained or a small adjustment is made. If it is a trend change, i.e., the deviation shows a continuous widening trend, the speed adjustment is increased in time to ensure that the pressure steadily approaches the target value. When the pressure reaches the preset value, the algorithm enters the stable maintenance phase: at this time, the pressure deviation is extremely small, and the historical average of the squared deviation decay is also at a low level. The algorithm further narrows the speed adjustment range, making only small adjustments each time. By adjusting the pump's output frequency, the impeller speed is kept in the optimal range, which not only offsets the pressure fluctuations caused by changes in pipeline resistance but also avoids pump overload, providing a continuous and stable power for the working fluid to be delivered to the preheater and evaporator.

[0081] The pressurized liquid organic working fluid is transported to the preheater, where it is initially heated by medium-temperature flue gas to obtain preheated organic working fluid. Specifically, this involves: after the organic working fluid pump pressurizes the liquid organic working fluid to a preset working pressure, opening the valve on the delivery pipeline between the pump outlet and the preheater working fluid inlet, and simultaneously adjusting the flow regulating valve on the pipeline to control the pressurized liquid organic working fluid flow at a rate of 5 to 10 m³ / min. 3 A stable flow rate is delivered hourly to the working fluid channel inside the preheater; this flow rate is determined based on the preheater's heat exchange capacity. Simultaneously, flue gas from the third and fourth stages of the annular cooler, having undergone preliminary heat exchange and with a temperature between 80 and 120°C, is introduced into the preheater's flue gas channel. Due to the presence of cold air in the background, the medium-temperature flue gas that has not been excessively diluted by cold air needs to be screened. Inside the preheater, the working fluid channel and the flue gas channel achieve indirect heat exchange through metal heat exchange walls, avoiding direct contact and preventing flue gas impurities from contaminating the working fluid. As the pressurized liquid organic working fluid flows within the working fluid channel, it absorbs heat released by the medium-temperature flue gas, gradually increasing its own temperature. The temperature of the organic working fluid is monitored in real-time by a temperature sensor at the preheater outlet. When the working fluid temperature rises to near its saturation temperature at the corresponding pressure (typically by 5 to 10°C), preliminary heating is complete, yielding the preheated organic working fluid. At this point, the inlet valve for that batch of medium-temperature flue gas is closed, preparing to switch to the next batch, ensuring a continuous and stable preheating process.

[0082] The preheated organic working fluid is then fed into the evaporator, where it is heated by the high-temperature flue gas, causing it to transform into a saturated or superheated steam state, thus completing the regeneration process. Specifically, after the preheated organic working fluid flows out of the preheater outlet, the valve between the preheater outlet and the evaporator working fluid inlet is opened, allowing the preheated organic working fluid to be transported to the evaporator's working fluid chamber. Subsequently, high-temperature flue gas from the latter part of the annular cooler, which has not been significantly infiltrated by cold air and has a temperature between 150 and 200°C, is introduced into the evaporator's flue gas chamber. The relatively concentrated residual heat from this flue gas meets the evaporation requirements of the working fluid. The evaporator employs a shell-and-tube heat exchange structure, with the preheated organic working fluid flowing in the tube side and the high-temperature flue gas flowing in the shell side. The two exchange heat efficiently and indirectly through the heat exchange tube walls. During the heat exchange process, the high-temperature flue gas releases a large amount of heat energy, which is transferred to the organic working fluid in the tube. The organic working fluid first gradually heats up from the preheated liquid state to the saturation temperature at the corresponding pressure, and then continues to absorb heat, starting a phase change and gradually transforming from a liquid state to a gaseous state. After a period of continuous heat exchange, the organic working fluid completely evaporates and further absorbs heat, raising the temperature of the gaseous working fluid above the saturation temperature, forming a saturated or superheated steam state. The superheated temperature is usually controlled between 5 and 15°C to ensure that the steam quality meets the power requirements of the generator set. The temperature, pressure, and dryness are monitored by the steam parameter monitor at the evaporator outlet. After confirming that the organic working fluid has stabilized in a saturated or superheated steam state, the supply of batches of high-temperature flue gas is stopped, completing the regeneration process of the working fluid.

[0083] The regenerated organic working fluid steam is reintroduced into the generator set to begin a new heat exchange cycle. Specifically, after the organic working fluid has been regenerated and forms stable saturated or superheated steam, the steam pipeline valve between the evaporator steam outlet and the generator set turbine inlet is opened. The generator set mainly consists of a turbine and a generator. Simultaneously, the steam regulating valve on the pipeline is adjusted to control the steam delivery pressure and flow rate, ensuring it matches the turbine's design operating conditions and preventing turbine instability caused by steam parameter fluctuations. The regenerated organic working fluid steam enters the turbine's flow path at a stable flow rate. Inside the turbine, the steam expands and performs work, driving the turbine impeller to rotate at a high speed of 3000 revolutions per minute. This speed meets the generator's power generation frequency requirements. Since the turbine and generator are coaxially connected via a coupling, the turbine impeller's rotation drives the generator rotor to rotate synchronously. The generator then converts mechanical energy into electrical energy, achieving waste heat power generation. After the batch of steam completes its work in the turbine, its pressure and temperature drop significantly, becoming a low-pressure gaseous organic working fluid. It then enters the condenser to begin the next condensation process, continuously introducing the newly regenerated organic working fluid steam in the evaporator into the generator set, so that the entire heat exchange cycle can continue. This ensures that the system can continuously utilize the low-temperature flue gas waste heat of the steel sintering ring cooler to generate electricity, making up for the deficiency of insufficient heat recovery in the background.

[0084] In this embodiment of the invention, the present invention first receives the liquid organic working fluid that has completed phase change condensation at the outlet of the condenser via an organic working fluid pump, pressurizes it to a preset working pressure, then sends the pressurized working fluid to a preheater for initial heating with medium-temperature flue gas, then sends it to an evaporator for heating with high-temperature flue gas to a saturated or superheated steam state to complete the working fluid regeneration, and finally guides the regenerated working fluid steam back to the generator set. This integrated technology of working fluid pressurization, staged temperature heating and recycling overcomes the technical problems of the liquid organic working fluid pressure being too low after condensation to provide power for subsequent heat exchange, the working fluid being directly exposed to high-temperature flue gas without preheating, which can easily lead to incomplete phase change due to excessive heat exchange temperature difference, and the working fluid circulation link being broken, which affects the continuous operation of the ORC system. In this way, the organic working fluid can fully absorb the waste heat resources at different temperature levels of medium and high temperature on the basis of meeting the pressure standard, and stably complete the phase change regeneration from liquid to qualified steam. This not only ensures the continuous stability of the working fluid circulation, but also makes up for the deficiency of insufficient heat supply caused by the drop in flue gas temperature in the background, and improves the energy conversion efficiency and long-term operational reliability of the ORC low-temperature waste heat power generation system.

[0085] In a preferred embodiment of the present invention, the preheated organic working fluid is further fed to an evaporator, where it is heated by high-temperature flue gas to transform into a saturated or superheated steam state, thus completing the regeneration process of the working fluid, including:

[0086] The process involves obtaining a preheated organic working fluid output from a preheater and then conveying it to the working fluid inlet of the evaporator to obtain the working fluid to be heated. Specifically, this includes: opening the valve on the conveying pipeline between the preheater outlet and the evaporator working fluid inlet, allowing the preheated organic working fluid, heated by the preheater, to flow out from the preheater outlet and into a dedicated working fluid conveying pipeline. The outer layer of the working fluid conveying pipeline is wrapped with an insulation layer to prevent the working fluid from cooling down during the conveying process, thus avoiding affecting the subsequent heat exchange efficiency. By adjusting the flow control valve on the pipeline, the conveying flow rate of the preheated organic working fluid is controlled to ensure that the working fluid is continuously and stably conveyed to the working fluid inlet of the evaporator. After the working fluid smoothly enters the working fluid inlet chamber of the evaporator, the working fluid to be heated is obtained.

[0087] The condition monitoring of the working fluid to be heated is performed to confirm that it meets the evaporator inlet operating conditions. Specifically, this includes activating the condition monitoring device at the evaporator inlet after the working fluid enters the evaporator inlet chamber. This device collects the temperature and pressure data of the working fluid in real time. Temperature monitoring must ensure that the working fluid temperature reaches the preset range after preheating, and pressure monitoring must confirm that the working fluid pressure meets the design pressure requirements of the evaporator inlet. The settings of these two parameters need to be combined with the evaporation temperature requirements of the ORC unit for the organic working fluid, while also considering the possible fluctuations in the working fluid state due to the infiltration of cold air in the background. The real-time collected temperature and pressure data are compared with the preset evaporator inlet operating condition standards. If the data are both within the standard range, the working fluid to be heated is confirmed to meet the evaporator inlet operating conditions. If the data exceeds the standard range, the heating parameters of the preheater or the working fluid delivery flow rate are adjusted until the working fluid state meets the requirements.

[0088] The process involves the working fluid, once it meets the required operating conditions, indirectly exchanging heat with the high-temperature flue gas within the evaporator to absorb its thermal energy. Specifically, after confirming that the working fluid meets the evaporator inlet operating conditions, the valve at the evaporator flue gas inlet is opened, introducing the high-temperature flue gas from the latter part of the annular cooler, which has not been significantly infiltrated by cold air, into the evaporator's flue gas channel. Before introduction, the high-temperature flue gas must be filtered to remove dust and impurities, preventing them from adhering to the heat exchange tube walls and affecting heat exchange efficiency. The evaporator employs a shell-and-tube heat exchange structure. The working fluid flows within the tube side of the evaporator, while the high-temperature flue gas flows within the shell side. Indirect heat exchange occurs between the two through the metal heat exchange tube walls. During this process, the heat energy released by the high-temperature flue gas is transferred to the working fluid within the tube side through the tube walls. The working fluid continuously absorbs heat energy, and its temperature gradually increases.

[0089] The heat exchange process is controlled to cause the working fluid to undergo a phase change from liquid to gas, resulting in organic working fluid vapor with a preset superheat. Specifically, this involves: during the absorption of heat energy from high-temperature flue gas by the working fluid, the heat exchange control device in the evaporator is activated. The heat exchange control device controls the heat exchange intensity by adjusting the flow rates of the high-temperature flue gas and the working fluid, gradually raising the temperature of the working fluid to its saturation temperature at its corresponding pressure. At this point, a small number of bubbles begin to appear in the working fluid, entering the initial stage of phase change. Stable heat exchange conditions are maintained, allowing the working fluid to continue absorbing heat energy, and the number of bubbles gradually increases, as the working fluid gradually transforms from liquid to gas. Once the working fluid has completely transformed into a gaseous state, the heat exchange parameters are adjusted to further raise the temperature of the gaseous working fluid until the preset superheat is reached, ultimately obtaining organic working fluid vapor with the preset superheat. This avoids liquid slugging during subsequent turbine operation due to insufficient superheat.

[0090] Organic working fluid steam is output from the steam outlet of the evaporator to obtain regenerated working fluid steam. Specifically, after obtaining organic working fluid steam with a preset superheat, the valve of the evaporator steam outlet is opened, and the parameter monitoring device at the steam outlet is activated to monitor the temperature, pressure, and dryness of the steam in real time to ensure that the steam quality meets the requirements of the turbine. The organic working fluid steam enters a dedicated steam delivery pipeline through the steam outlet. This pipeline is also wrapped with an insulation layer to prevent the steam temperature from dropping or condensing during transportation due to heat dissipation. The steam is output from the evaporator steam outlet at a stable flow rate and finally delivered to the steam inlet of the turbine. At this point, the regenerated working fluid steam that has completed the regeneration process is obtained, providing a qualified power source for the turbine to convert thermal energy into mechanical energy, thereby compensating for the low power generation efficiency of ORC units caused by insufficient recovery of waste heat from low-temperature flue gas in the background.

[0091] In this embodiment of the invention, the present invention employs an integrated technology of working condition verification, directional indirect heat exchange, controllable phase change process, and precise output of regenerated steam. This overcomes the problem of uneven heat exchange caused by the unstable state of the preheated organic working fluid directly entering the evaporator. The technology involves first acquiring the preheated organic working fluid output from the preheater and then conveying it to the working fluid inlet of the evaporator. After confirming that the working fluid meets the evaporator inlet operating conditions through state monitoring, the working fluid undergoes indirect heat exchange with high-temperature flue gas within the evaporator. Then, by controlling the heat exchange process, the working fluid completes a phase change from liquid to gas, forming steam with a preset superheat. Finally, regenerated working fluid steam is output from the evaporator steam outlet. This integrated technology overcomes the problem of uneven heat exchange caused by the unstable state of the preheated organic working fluid directly entering the evaporator. The system addresses technical issues such as incomplete phase change, poor steam quality failing to meet turbine operating requirements, and temperature fluctuations in high-temperature flue gas caused by cold air infiltration in the background, which exacerbate instability in the working fluid regeneration process. It ensures that the working fluid efficiently and stably absorbs heat energy from the high-temperature flue gas within the evaporator, precisely completing the phase change from liquid to gas and forming superheated steam that meets preset standards. This guarantees the quality of the steam driving the turbine and improves the reliability and efficiency of the organic working fluid regeneration process. Furthermore, it compensates for insufficient waste heat recovery from low-temperature flue gas in the background, providing a stable working fluid guarantee for the efficient operation of the ORC low-temperature waste heat power generation system.

[0092] In a preferred embodiment of the present invention, based on a heat exchange cycle, the cooled hot water is returned to the flue gas and hot water heat exchanger by a hot water circulation pump to reabsorb the waste heat of the flue gas, including:

[0093] The process involves obtaining cooled hot water returned from the heating system and pressurizing it to a preset circulation pressure. Specifically, this includes: First, opening the return water valve between the heating or process water unit and the hot water circulation system, allowing the cooled hot water, which has cooled after use in the heating or process water unit, to flow into the inlet chamber of the hot water circulation pump through the return water pipe. During the inflow of cooled hot water, a flow monitoring device on the pipeline continuously monitors the water flow rate to ensure a stable flow into the pump and prevent pump instability due to flow fluctuations. Then, the hot water circulation pump is started, and the high-speed rotation of the impeller inside the pump applies mechanical pressure to the cooled hot water, gradually increasing the pressure value. During pressurization, a pressure sensor at the outlet of the hot water circulation pump continuously monitors the hot water pressure and adjusts it to a preset circulation pressure value. This preset pressure value is determined based on the inlet pressure requirements of the subsequent flue gas and hot water heat exchanger, as well as the resistance loss of the entire hot water delivery pipeline, ensuring that the pressurized hot water can overcome pipeline resistance and be stably delivered to the heat exchanger. Once the pressure reaches the preset standard, maintain a stable output power of the hot water circulation pump to provide continuous power for hot water delivery.

[0094] Pressurized hot water is delivered to the inlet of the flue gas and hot water heat exchanger, where it undergoes countercurrent heat exchange with the medium- and low-temperature flue gas, absorbing residual heat from the flue gas and increasing in temperature to obtain heated hot water. Specifically, after confirming that the hot water pressure has reached the preset circulation pressure, the valve of the delivery pipeline between the hot water circulation pump outlet and the inlet of the flue gas and hot water heat exchanger is opened, allowing the pressurized hot water to be smoothly delivered to the inlet of the flue gas and hot water heat exchanger through a dedicated delivery pipeline, entering the hot water channel inside the heat exchanger. The valve of the flue gas delivery pipeline of the third and fourth sections of the annular cooler is opened, introducing the medium- and low-temperature flue gas generated by the third and fourth sections of the annular cooler into the flue gas channel of the flue gas and hot water heat exchanger. Before the flue gas is introduced, it is first removed by a flue gas filtration device to remove dust and impurities from the flue gas, preventing impurities from adhering to the heat exchanger tube wall and affecting subsequent heat exchange efficiency. The flue gas and hot water heat exchanger adopts a counter-current heat exchange structure design. The pressurized hot water flows from bottom to top in the tube side of the heat exchanger, while the medium- and low-temperature flue gas flows from top to bottom in the shell side. The two are indirectly in contact and exchange heat through the heat exchange tube walls. During the heat exchange process, the medium- and low-temperature flue gas releases its own waste heat, which is transferred to the hot water in the tube side through the tube walls. The hot water gradually increases in temperature after continuously absorbing the waste heat. The medium- and low-temperature flue gas decreases in temperature after releasing heat and is eventually discharged from the flue gas outlet of the heat exchanger. The temperature change of the hot water is observed in real time through temperature monitoring points inside the heat exchanger to ensure that the hot water can effectively absorb the waste heat of the flue gas during the heat exchange process.

[0095] The heated hot water is drawn from the outlet of the flue gas and hot water heat exchanger and re-transported to the heating water supply, completing the hot water recycling process. Specifically, after the hot water completes heat exchange in the heat exchanger and its temperature rises to the preset operating temperature, the valve at the heat exchanger outlet is opened, allowing the heated hot water to flow through the outlet into a dedicated hot water delivery pipeline. The outer layer of the hot water delivery pipeline is wrapped with insulation material to prevent the temperature from dropping due to heat exchange with the external environment during transportation, thus avoiding affecting the usage needs of subsequent heating or process water units. During the transportation of the heated hot water, the temperature drops due to heat exchange with the external environment. Temperature sensors monitor the hot water temperature in real time to ensure that the water temperature is always kept within the range that meets the requirements of heating or process water. The heated hot water is then transported back to the inlet of the heating or process water unit through the delivery pipeline, continuously providing the heating or process water unit with hot water that meets the temperature requirements. An automatic water replenishment device is installed on the water replenishment pipeline of the hot water circulation system. When the amount of hot water decreases due to evaporation or minor pipeline leakage during the circulation process, the automatic water replenishment device will add an appropriate amount of softened water to the system to maintain a stable total amount of circulating hot water, ensuring that the entire hot water circulation process is continuous and reliable, forming a complete closed loop of hot water heat exchange circulation.

[0096] In this embodiment of the invention, the present invention employs a closed-loop recycling technology that first obtains the cooled hot water returned from the heating or process water unit and pressurizes it to a preset circulation pressure. Then, the pressurized hot water is transported to the inlet of the flue gas and hot water heat exchanger to exchange heat with the medium and low temperature flue gas in a countercurrent manner to absorb waste heat and raise the temperature. Finally, the heated hot water is drawn out from the outlet of the heat exchanger and transported back to the heating or process water unit for pressurization-countercurrent heat exchange and heat absorption. This technology effectively overcomes the technical problems of insufficient pressure preventing the cooled hot water from being stably transported back to the heat exchanger, inefficient heat exchange with medium and low temperature flue gas leading to insufficient heat absorption, and the inability to recycle hot water causing waste heat and affecting the stable supply of heating / process water. This ensures that the hot water can circulate stably and efficiently absorb the waste heat of medium and low temperature flue gas to raise the temperature. It fully utilizes the low temperature flue gas waste heat that has not been fully extracted in the background, realizes the closed-loop recycling of hot water, reduces water consumption, and ensures a stable heat source supply for the heating or process water unit. This further improves the energy utilization efficiency and practicality of the entire steel sintering flue gas waste heat recovery system.

[0097] In a preferred embodiment of the present invention, water is drawn from the cold water pool and pressurized and transported to the condenser by a circulating cooling water pump. After absorbing heat in the condenser, the cooling water is cooled by a cooling tower and returned to the cold water pool, thus obtaining separate circulation loops for hot water and cooling water, including:

[0098] Cooling water is drawn from a cold water tank and pressurized to reach the inlet pressure required by the condenser. This pressurized cooling water process involves: opening the valve between the cold water tank outlet and the circulating cooling water pump inlet, allowing the stored cooling water to slowly flow into the pump's inlet chamber under gravity. During this flow, the water level in the inlet chamber is monitored by a level monitoring device on the pipeline to prevent damage from low water levels. Once the cooling water level in the inlet chamber reaches the preset height, the circulating cooling water pump is started. The pump applies mechanical pressure to the cooling water through the high-speed rotation of its internal impeller, gradually increasing the pressure. During pressurization, the cooling water pressure is monitored in real time by a pressure sensor at the pump outlet, and the pressure is adjusted to the condenser's required inlet pressure. Once the pressure stabilizes at the preset standard, the pump's output power is maintained to provide continuous and stable power for subsequent cooling water delivery.

[0099] Pressurized cooling water is supplied to the cooling water inlet of the condenser, allowing it to indirectly exchange heat with the organic working fluid vapor. The pressurized cooling water absorbs the latent heat of condensation of the organic working fluid and thus heats up, resulting in heated cooling water. Specifically, after confirming that the cooling water pressure reaches the required inlet pressure of the condenser, the valve on the delivery pipeline between the circulating cooling water pump outlet and the condenser cooling water inlet is opened. Simultaneously, the flow regulating valve on the pipeline is adjusted to control the pressurized cooling water to be supplied to the condenser cooling water inlet at a stable flow rate. This allows the cooling water to enter the tube-side channels inside the condenser. The low-pressure organic working fluid vapor generated after the turbine's work has already been delivered to the condenser through the pipeline. The shell-side inlet leads into the shell-side channel. Inside the condenser, the pressurized cooling water in the tube side and the low-pressure organic working fluid vapor in the shell side exchange heat indirectly through the metal heat exchange tube walls. The two do not come into direct contact, thus avoiding contamination of the working fluid by the cooling water. During the heat exchange process, the low-pressure organic working fluid vapor releases its latent heat of condensation. This heat is transferred to the cooling water in the tube side through the heat exchange tube walls. As the cooling water continuously absorbs heat, its temperature gradually increases, eventually becoming heated cooling water. During the heat exchange process, the temperature change of the cooling water is observed in real time through temperature monitoring points inside the condenser to ensure that the cooling water can effectively absorb the latent heat of condensation and ensure that the organic working fluid vapor is fully condensed.

[0100] The heated cooling water is transported to the cooling tower for heat dissipation and cooling, reducing its temperature to a preset range. The cooled water is then returned to the cold water tank, completing the cooling water circulation loop. Specifically, after the cooling water completes heat exchange in the condenser and its temperature rises to the preset upper temperature limit, the valve on the delivery pipeline between the condenser cooling water outlet and the cooling tower inlet is opened, allowing the heated cooling water to be transported to the cooling tower's inlet chamber through a dedicated pipeline. Once the cooling tower starts, the internal spray system evenly sprays the heated cooling water in a mist onto the packing layer. Simultaneously, the fan at the bottom of the cooling tower starts, drawing in ambient air and causing it to flow upwards from the bottom of the packing layer, creating a counter-current contact with the sprayed cooling water mist. During this contact process... Part of the heat from the cooling water is transferred to the air through evaporation and convection. After absorbing the heat, the air is discharged from the top of the cooling tower, and the cooling water temperature gradually decreases. The cooling water temperature is monitored in real time by a temperature sensor at the cooling tower outlet and adjusted to a preset range. Once the cooling water temperature drops to the preset standard, the outlet valve at the bottom of the cooling tower is opened, allowing the cooled cooling water to be returned to the cold water pool through the return water pipe to replenish the water volume of the cold water pool. An automatic water replenishment device is installed on the water replenishment pipe of the cold water pool. When the cooling water volume decreases due to evaporation during the circulation process, the automatic water replenishment device will add an appropriate amount of softened water to the cold water pool to maintain a stable water level in the cold water pool, thus obtaining a complete cooling water circulation loop and continuously providing a low-temperature cooling medium for the condenser.

[0101] In this embodiment of the invention, the present invention employs an integrated technology for pressurizing, heat exchange, and cooling reuse of cooling water. This technology involves obtaining cooling water from a cold water pool, pressurizing it to reach the required inlet pressure for the condenser, then delivering the pressurized cooling water to the condenser for indirect heat exchange with the organic working fluid vapor. Finally, the heated cooling water is sent to a cooling tower for heat dissipation and cooling, and then returned to the cold water pool, forming a closed-loop cycle. This effectively overcomes the technical problems of insufficient cooling water pressure failing to meet the condenser's inlet water requirements, resulting in insufficient heat exchange, low condensation efficiency of the organic working fluid vapor, and the waste of water resources caused by direct discharge of cooling water after a single use, which also fails to continuously provide a low-temperature cooling medium for the condenser. This ensures that the pressurized cooling water can efficiently absorb the latent heat of condensation of the organic working fluid vapor, guaranteeing that the organic working fluid is fully condensed into a liquid state to support the next cycle of working fluid circulation. Simultaneously, it achieves the recycling of cooling water, reducing water consumption and maintaining the long-term stable cooling capacity of the condenser. This provides a reliable cooling guarantee for the continuous and efficient operation of the ORC low-temperature waste heat power generation system, further improving the overall efficiency of waste heat recovery from steel sintering flue gas.

[0102] Embodiments of the present invention also provide a computing device, including: a processor and a memory storing a computer program, wherein the computer program, when executed by the processor, performs the system as described above. All implementations in the above system embodiments are applicable to this embodiment and can achieve the same technical effects.

[0103] Embodiments of the present invention also provide a computer-readable storage medium storing instructions that, when executed on a computer, cause the computer to perform the system as described above. All implementations in the above system embodiments are applicable to this embodiment and can achieve the same technical effects.

[0104] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A cascade utilization system based on steel sintering flue gas waste heat recovery, characterized in that, include: The recovery module is used to recover the waste heat of the low-temperature flue gas in the third and fourth stages of the steel sintering ring cooler through the flue gas and hot water heat exchanger. It exchanges the heat of the low-temperature flue gas with the closed-loop hot water, so that the hot water is heated, and then sends the heated hot water into the evaporator and preheater of the low-temperature waste heat power generation unit. The evaporation module is used in the evaporator and preheater to indirectly exchange heat between the liquid organic working fluid and the supplied hot water, absorbing the heat energy from the hot water to obtain slightly superheated high-pressure organic working fluid steam. This high-pressure organic working fluid steam is then introduced into the turbine to drive the turbine impeller to rotate and perform work. The module includes: The low-temperature, low-pressure liquid organic working fluid in the condenser is pressurized by an organic working fluid pump to obtain a high-pressure liquid organic working fluid. High-pressure liquid organic working fluid is delivered to the working fluid inlet of the preheater; hot water cooled after heat exchange in the evaporator of the low-temperature waste heat power generation unit is delivered to the hot water inlet of the preheater. Simultaneously, an ant colony optimization algorithm is activated, treating the combination of working fluid and hot water flow rates as the optimal path. The goal is to rapidly heat the working fluid to near-saturated liquid state and stabilize the heat exchange temperature difference. The optimal flow ratio is found through swarm iteration, with each ant representing a flow ratio combination. The swarm size is set to 15-20 groups, and the flow range is limited to the safe operating range of the preheater. The algorithm imports high-quality cases from historical heat exchange data as initial reference pheromones. Indirect heat exchange is initiated in the preheater, and the flow ratio corresponding to each ant is the same. The process is being tested. Temperature sensors collect real-time data on the working fluid outlet temperature and the temperature difference between the hot water inlet and outlet, which is fed back to the algorithm as a path score. Flow ratios with working fluid temperatures close to saturated liquid and small temperature fluctuations are marked as high-scoring, and the algorithm increases their pheromone concentration. Conversely, it decreases the pheromone concentration. In the next iteration, the ants will prioritize flow ratios with high pheromone concentrations, retaining a small amount of random exploration for continuous optimization. When, in three consecutive iterations, the working fluid outlet temperature deviation of the optimal flow ratio is less than or equal to ±2℃ and the temperature fluctuation is ≤±1℃, the algorithm determines that the optimization is complete and locks this ratio as a stable operating parameter. The algorithm continues to monitor the data and gradually increases the temperature to near saturated liquid. The pre-heated high-pressure liquid organic working fluid is sent to the evaporator to exchange heat indirectly with the high-temperature hot water in the flue gas and hot water heat exchanger, absorbing heat energy, so that the working fluid is further heated until it is completely evaporated and becomes slightly superheated high-pressure organic working fluid steam. Slightly superheated high-pressure organic working fluid steam is introduced into a turbine, so that the pressure energy of the organic working fluid steam is converted into mechanical energy, which drives the turbine impeller to rotate and do work. The condensation module is used to generate low-pressure organic working fluid vapor by rotating the turbine impeller and connecting to the generator to generate electricity. The organic working fluid vapor is then introduced into the condenser, where the cooling water in the condenser releases heat, causing the condensate to be reduced to liquid organic working fluid. The pressurization module is used to pressurize the condensed liquid organic working fluid through the organic working fluid pump and send it back to the preheater and evaporator to re-participate in the heat exchange cycle; The circulation module is used to send the cooled hot water back to the flue gas and hot water heat exchanger to reabsorb the waste heat of the flue gas based on the heat exchange cycle. The circulating cooling water pump draws water from the cold water pool, pressurizes it and sends it to the condenser. After absorbing heat in the condenser, the cooling water is cooled by the cooling tower and returned to the cold water pool, thus obtaining the respective circulation loops of hot water and cooling water.

2. The cascade utilization system based on steel sintering flue gas waste heat recovery according to claim 1, characterized in that, Waste heat from the low-temperature flue gas in the third and fourth stages of the steel sintering ring cooler is recovered through a flue gas-hot water heat exchanger. This heat is then transferred to the closed-loop hot water system, heating the water, which is then fed into the evaporator and preheater of the low-temperature waste heat power generation unit. This process includes: The return water after cooling by the low-temperature waste heat power generation unit is diverted and sent to the first hot water heater installed in the dust removal pipeline at the tail of the sintering machine and the second hot water heater installed at the material discharge dust removal position of the annular cooler. The return water is initially heated by the waste heat of the dust removal flue gas to obtain the first stage of heated hot water. The first-stage heated hot water is collected and sent to the third hot water heater located in the middle and rear section of the annular cooler. Driven by the annular cooler blower, the waste heat of the third-stage flue gas after penetrating the material layer of the annular cooler is used to deeply heat the first-stage heated hot water to obtain the second-stage heated hot water. The second-stage heated water is sent to the fourth hot water heater located in the fourth section of the annular cooler. Driven by a low-temperature circulating fan, the closed-loop circulating flue gas formed after penetrating the material layer provides the final heating for the second-stage heated water, bringing it to the preset design temperature. Hot water that has reached the design temperature is uniformly transported to the evaporator and preheater of the low-temperature waste heat power generation unit to transfer the heat energy of the hot water to the organic working fluid.

3. The system according to claim 2, wherein the system is characterized by, The turbine impeller rotates to perform work, and a connected generator generates electricity, producing low-pressure organic working fluid vapor. This vapor is then introduced into a condenser, where cooling water releases heat, reducing the condensate back to liquid organic working fluid, including: The low-pressure organic working fluid vapor, after being expanded and worked by the turbine, is introduced into the condenser; Based on the low-pressure organic working fluid vapor in the condenser, it indirectly exchanges heat with the cooling water, releases the latent heat of vaporization to the cooling water, and cools the low-pressure organic working fluid vapor and transforms it into a saturated liquid working fluid. By subjecting a saturated liquid working fluid to subcooling, the temperature of the liquid working fluid is lowered, resulting in a low-temperature, low-pressure liquid organic working fluid with subcooling.

4. The cascade utilization system based on waste heat recovery from iron and steel sintering flue gas according to claim 3, characterized in that, The condensed liquid organic working fluid is pressurized by an organic working fluid pump and sent back to the preheater and evaporator to re-participate in the heat exchange cycle, including: The liquid organic working fluid that has undergone phase change condensation is received, and the liquid organic working fluid is pressurized by an organic working fluid pump to increase the pressure of the liquid organic working fluid to a preset working pressure value, so as to obtain pressurized liquid organic working fluid. The pressurized liquid organic working fluid is transported to the preheater, where it is initially heated by medium-temperature flue gas to obtain preheated organic working fluid. The preheated organic working medium is then fed to the evaporator, where it is heated by the high-temperature flue gas, causing it to change phase to saturated or superheated steam, thus completing the regeneration process of the working medium. The regenerated organic working fluid steam is reintroduced into the generator set to start a new heat exchange cycle.

5. The steel sintering flue gas waste heat recovery-based cascade utilization system according to claim 4, characterized in that, The preheated organic working fluid is then fed into an evaporator, where it is heated by high-temperature flue gas, causing it to transform into a saturated or superheated steam state, thus completing the regeneration process. This process includes: The preheated organic working fluid output after being heated by the preheater is obtained, and the preheated organic working fluid is transported to the working fluid inlet of the evaporator to obtain the working fluid to be heated; The working fluid to be heated is monitored to confirm that it meets the inlet operating conditions of the evaporator. The working fluid that meets the operating conditions can indirectly exchange heat with the high-temperature flue gas in the evaporator and absorb the heat energy of the high-temperature flue gas. The heat exchange process is controlled to cause the working fluid to undergo a phase change process from liquid to gas, resulting in organic working fluid vapor with a preset superheat. Organic working fluid steam is output from the steam outlet of the evaporator to obtain regenerated working fluid steam.

6. The steel sintering flue gas waste heat recovery-based cascade utilization system according to claim 5, characterized in that, Based on the heat exchange cycle, the cooled hot water is returned to the flue gas and hot water heat exchanger via a hot water circulation pump to reabsorb the waste heat from the flue gas, including: The cooled hot water returned from the heating system is obtained, and the cooled hot water is pressurized to reach the preset circulation pressure to obtain pressurized hot water. The pressurized hot water is delivered to the inlet of the flue gas and hot water heat exchanger, so that the pressurized hot water delivered to the heat exchanger exchanges heat with the medium and low temperature flue gas in a countercurrent manner, absorbing the waste heat in the flue gas and raising its temperature to obtain heated hot water. The heated water is drawn out from the outlet of the flue gas and hot water heat exchanger and then transported back to the heating water supply, thus completing the recycling of hot water.

7. The cascade utilization system based on waste heat recovery from iron and steel sintering flue gas according to claim 6, characterized in that, Water is drawn from the cold water pool and pressurized by a circulating cooling water pump and transported to the condenser. After absorbing heat in the condenser, the cooling water is cooled by a cooling tower and returned to the cold water pool, resulting in separate circulation loops for hot water and cooling water, including: Cooling water to be used is obtained from the cold water pool and pressurized to reach the inlet pressure required by the condenser, thus obtaining pressurized cooling water. Pressurized cooling water is delivered to the cooling water inlet of the condenser, so that the pressurized cooling water delivered to the condenser can exchange heat indirectly with the organic working fluid vapor, absorb the latent heat of condensation of the organic working fluid and rise in temperature, and obtain heated cooling water. The heated cooling water is transported to the cooling tower for heat dissipation and cooling down, so that the temperature of the cooling water drops to the preset range. The cooled cooling water is then returned to the cold water pool, completing the cooling water circulation loop.

8. A computing device, comprising: include: One or more processors; A storage device for storing one or more programs, which, when executed by one or more processors, cause the one or more processors to implement the system as described in any one of claims 1 to 7.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a program that, when executed by a processor, performs the system as described in any one of claims 1 to 7.

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