System for treating process fluid

Abstract

The present invention relates to a system for treating a process fluid and, more specifically, to a system for treating a process fluid, the system recovering waste heat from a process fluid via heat exchange which is conducted by switching, according to the phase of the process fluid, between two condensers having different heat exchange capacities from one another, such that the system responds to the phase of the process fluid, which changes according to whether steam for recovering waste heat is generated, and thus can improve operation stability.

Description

Process fluid handling systems

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority from Korean Patent Application No. 10-2023-0189501, filed December 22, 2023, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to a process fluid treatment system, and more particularly, to a process fluid treatment system capable of improving operational stability by switching and operating two condensers with different heat exchange capacities to exchange heat in response to the phase of the process fluid, which varies depending on whether steam is generated for waste heat recovery in a process of recovering waste heat from the process fluid.

[0005] Petrochemical processes consume significant energy to produce products, and this energy is either discarded or reused. Steam, the energy source for these processes, is typically generated using boilers from the combustion heat of hydrocarbon fuels. However, this process is expensive and releases carbon dioxide into the atmosphere through combustion, contributing to global warming. Therefore, waste heat utilization is emerging as a way to reduce steam usage within the process to reduce carbon emissions and lower the manufacturing costs of petrochemical products.

[0006] Typically, petrochemical products are manufactured through processes involving reaction, separation, and refining. When the bottom of the column where these processes are performed is heated using steam, high-temperature process fluids are generated at the top of the column. These high-temperature fluids can serve as waste heat, and a large amount of heat is wasted as they are cooled through heat exchange with cooling water in heat exchangers such as condensers and coolers. The heated cooling water then flows into a cooling tower, where it dissipates heat and is cooled before being fed back to the heat exchanger. The heat released during this cooling process can be considered waste heat within the process.

[0007] To utilize waste heat within the process, boiler feedwater is heat-exchanged with high-temperature process fluid to generate steam, which is then utilized. Meanwhile, the process fluid, from which waste heat has been recovered, undergoes a series of processes, either being recycled back to the column or fed into subsequent processes (e.g., reaction or purification processes).

[0008] Specifically, the high-temperature process fluid discharged to the top of the column is converted into a two-phase vapor-liquid stream through heat exchange with boiler feedwater during steam generation, and this is condensed through a heat exchanger such as a condenser and then refluxed into the column. In this case, if only one condenser is used, there is a problem in that the stability risk of the process including the condenser is significantly increased because the conditions such as phase change and heat amount of the stream fed into the condenser vary depending on whether the steam generation system for waste heat recovery including the evaporator is operated.

[0009] The problem to be solved in the present invention is to provide a process fluid treatment system for stably operating a condensation process of a process fluid regardless of whether steam is generated when a system for recovering waste heat from a high-temperature process fluid generated in a petrochemical process is provided in order to solve the problem mentioned in the background technology of the above invention.

[0010] However, the problems that the present invention seeks to solve are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

[0011] According to one embodiment of the present invention for solving the above problem, the present invention provides a process fluid treatment system including, in a process of recovering waste heat from a process fluid, an evaporator that generates steam by using a gaseous process fluid stream supplied from a waste heat source as a heat source; a first condenser and a second condenser that receive the process fluid stream discharged from the evaporator and cool it by heat exchange with a refrigerant; and a condenser drum respectively connected to the first condenser and the second condenser by pipes.

[0012] Additionally, the first condenser may be connected to the evaporator through a first pipe, and the second condenser may be connected to a second pipe branched from the first pipe.

[0013] In addition, the first and second pipes are each provided with an openable valve, which can be opened and closed depending on the phase of the process fluid stream discharged from the evaporator.

[0014] According to the process fluid treatment system of the present invention, a system for recovering waste heat by generating steam through heat exchange with boiler feed water from a high-temperature process fluid as a waste heat source is provided, wherein a two-phase process fluid stream of vapor and liquid generated in a petrochemical process and a process fluid stream in a vapor state when no steam is generated are condensed by switching and operating condensers having different heat exchange capacities, thereby reducing the temperature deviation of the process fluid depending on whether steam is generated, thereby improving process stability.

[0015] The effects that can be obtained from this invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art to which the present invention pertains from the description below.

[0016] Figure 1 is a schematic diagram of a process for generating steam in a process fluid treatment system according to one embodiment of the present invention.

[0017] Figure 2 is a schematic diagram of a process fluid treatment system according to one embodiment of the present invention when steam is not generated.

[0018] Figure 3 is a schematic diagram of a conventional process fluid treatment process according to a comparative example.

[0019] The terms or words used in the description and claims of the present invention should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0020] In connection with the description of the drawings, similar reference numerals may be used for similar or related components.

[0021] The singular form of a noun corresponding to an item may include one or more of said items, unless the relevant context clearly indicates otherwise.

[0022] In this disclosure, each of the phrases "A or B", "at least one of A and B", "at least one of A or B", "A, B, or C", "at least one of A, B, and C", and "at least one of A, B, or C" may include any one of the items listed together in the corresponding phrase, or all possible combinations thereof.

[0023] The term “and / or” includes any combination of a plurality of related described elements or any one of a plurality of related described elements.

[0024] Terms such as "first," "second," or "first" or "second" may be used simply to distinguish one component from another and do not qualify the components in any other respect (e.g., importance or order).

[0025] In addition, terms such as 'front', 'rear', 'top', 'bottom', 'side', 'left', 'right', 'upper', and 'lower' used in this application are defined based on the drawings, and the shape and position of each component are not limited by these terms.

[0026] The terms “include” or “have” are intended to specify the presence of a feature, number, step, operation, component, part or combination thereof described in the present disclosure, but do not preclude the presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

[0027] When a component is said to be “connected,” “coupled,” “supported,” or “in contact with” another component, this includes not only cases where the components are directly connected, coupled, supported, or in contact, but also cases where the components are indirectly connected, coupled, supported, or in contact through a third component.

[0028] When we say that a component is “on” another component, this includes not only cases where the component is in contact with the other component, but also cases where there is another component between the two components.

[0029] In addition, the terms "about", "substantially", etc. used herein are used in the sense of or close to the numerical value when manufacturing and material tolerances inherent to the meanings mentioned are presented, and are used to prevent unscrupulous infringers from unfairly using the disclosure contents in which exact or absolute numerical values ​​are mentioned to aid understanding of the present invention.

[0030] The term "stream" as used herein may refer to the flow of fluid within a process, or may refer to the fluid itself flowing within a pipe. Specifically, the stream may refer to both the fluid itself flowing within the pipe connecting each device and the flow of the fluid. Furthermore, the fluid may include one or more components of gas, liquid, and solid.

[0031] The term "upper" as used herein, unless otherwise specified, refers to a point 0% to 20% in height downward from the top of the device, and may specifically refer to the top (top). In addition, the term "lower" refers to a point 80% to 100% in height downward from the top of the device, and may specifically refer to the bottom (bottom).

[0032] Additionally, “pressure” as referred to herein means gauge pressure measured based on atmospheric pressure.

[0033] Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings.

[0034] Figures 1 and 2 are schematic diagrams of a process fluid treatment process according to one embodiment of the present invention. Referring to Figures 1 and 2, the process fluid treatment system according to the present invention includes a plurality of heat exchangers (200, 310, 320) and a condenser drum (350) for recovering waste heat and treating process fluid.

[0035] A process fluid treatment system according to one embodiment of the present invention comprises: an evaporator (200) that generates steam (20) using a gaseous process fluid stream (10) supplied from a waste heat source as a heat source in a process of recovering waste heat from a process fluid; a first condenser (310) and a second condenser (320) that receive a process fluid stream (11, 12) discharged from the evaporator and cool it by heat exchange with a refrigerant (CW1, CW2); and a condenser drum (350) that is connected to the first condenser and the second condenser by pipes, respectively.

[0036] In general, in order to recycle waste heat generated in a petrochemical process, as illustrated in FIG. 3, instead of directly condensing the top discharge stream (10) of a column (100) in a condenser (300), an evaporator (200) is installed in front of the condenser to recover a portion of the waste heat of the column top discharge stream (10). In such a waste heat recovery system, boiler feed water (BFW) having a lower temperature than the column top discharge stream (10) is injected into the evaporator (200) to supply heat using the column top discharge stream (10) as a heat source, whereby a portion of the boiler feed water is vaporized to generate steam (20), and the steam (20) generated in the evaporator (200) ultimately generates steam at a desired pressure through a pressurization system (250).

[0037] However, in a process fluid treatment system including a waste heat recovery process, the waste heat of the column top discharge stream (10) may not be recovered through the evaporator (200) in some cases. For example, if the steam balance between the process fluid treatment system according to the present invention (i.e., the steam source) and an external system (i.e., the steam user) changes, the required steam production amount may change or steam production may be stopped, and at this time, the supply of boiler feedwater (BFW) to the evaporator may be stopped. In addition, if the pressurization system (250) fails to produce steam, the supply of boiler feedwater (BFW) may be temporarily stopped.

[0038] Meanwhile, in a process including a waste heat recovery system, the process fluid (11') from which waste heat has been recovered is generally supplied to a condenser (300), condensed, and then refluxed back to the column (100), as illustrated in FIG. 3. At this time, the condenser (300) and the condenser drum (350) require temperature control to an optimal temperature suited to the process characteristics, and the temperature control can be controlled by the flow rate of cooling water (CW) introduced into the condenser. In addition, the temperature of the stream (13') discharged from the condenser and the internal temperature of the condenser drum can be the same. More specifically, when operating as a partial condenser, the process fluid stream having the same vapor fraction can be discharged regardless of the change in the stream introduced into the condenser by controlling the temperature. On the other hand, when operating as a full condenser, if the temperature goes beyond the optimal temperature range suited to the process characteristics, problems with the stability of the process operation, such as corrosion, precipitation, and polymerization, may occur.

[0039] However, depending on whether the evaporator (200) is in operation, the operating range of the condenser (300) varies greatly. For example, when the total heat amount of the column top discharge stream (10) is condensed is 100%, in a system where the evaporator (200) condenses about 30% to 80% of the heat amount and the condenser (300) condenses the remaining 20% ​​to 70% of the heat amount, when the operation of the evaporator (200) is stopped, the condenser (300) must respond to a wide range of heat amounts between 20% and 100% with the same device for condensing the column top discharge stream (10). In this way, even though the phase change and required heat amount of the process fluid stream flowing into the condenser vary greatly depending on whether the evaporator is in operation, if a single condenser responds to a wide range of operating conditions as shown in FIG. 3, the thermal / mechanical stability of the condenser may be problematic.

[0040] Therefore, a process fluid treatment system that enables stable operation regardless of the evaporator's operation is needed in a process fluid treatment system that includes a waste heat recovery process. More specifically, a system is needed that can stably operate a condenser, whose operating conditions vary significantly depending on the evaporator's operation, and also more stably control the temperature of the condenser drum. Therefore, the present invention provides a process fluid treatment system that addresses the aforementioned issues.

[0041] The above waste heat source may be a high-temperature process fluid (10) generated in a column (100) where various processes such as reaction, separation, and purification are performed during the manufacture of petrochemical products. The temperature of this high-temperature process fluid (10) may vary depending on the conditions of each process, and may be in the range of approximately 50°C to 250°C, and specifically 70°C to 200°C.

[0042] Meanwhile, since processing the process fluid without separate heat recovery is not desirable from an energy perspective, recovering the heat of the waste heat source, i.e., the high-temperature process fluid, and utilizing the recovered heat in other processes requiring heat is essential for reducing the energy consumption of the entire process.

[0043] To this end, first, the high-temperature process fluid stream (10) and boiler feed water (BFW) for steam generation can be supplied to the evaporator (200). The process fluid (10) undergoes heat exchange with the boiler feed water (BFW) in the evaporator (200), so that the heat of the process fluid can be transferred to the boiler feed water (BFW).

[0044] Additionally, the boiler feedwater (BFW) may be a feed for generating steam for waste heat utilization. Specifically, boiler feedwater vaporized by heat transferred from the process fluid in the evaporator (200) may be converted into steam (20).

[0045] The steam (20) discharged from the above evaporator (200) can be post-processed using a pressurization system (250) to compress it to high temperature and high pressure, and such high temperature and high pressure steam can be used as an energy source for various petrochemical processes. Here, the pressurization system (250) may be a mechanical vapor recompression (MVR) system equipped with a device such as one or more stages of a compressor and / or a blower, or a thermal vapor recompression (TVR) system equipped with a device such as an ejector. The pressurization system (250) may be, for example, an assembly in which two or more compressors are combined, or a compression unit including one or more compressors, but is not limited thereto.

[0046] According to one embodiment of the present invention, the boiler feed water (BFW) of the evaporator is water, and waste heat can be recovered by supplying the water to the evaporator (200) to generate steam (20) through heat exchange. The evaporator (200) is a device that is connected to a column (100) from which a waste heat source is discharged and transfers waste heat from a process fluid to the boiler feed water to discharge steam.

[0047] The above evaporator (200) is a type of heat exchanger commonly used in petrochemical processes, and the heat exchanger applicable to the present invention may be a shell and tube type, and a plate type or falling film evaporator type may also be used to increase heat exchange efficiency, but is not limited thereto.

[0048] Specifically, since the process fluid may have different fluid properties such as its composition and temperature, the temperature and pressure conditions of the boiler feedwater may be different accordingly. In the evaporator (200), boiler feedwater (BFW) in a liquid state, for example, boiler feedwater of 40°C to 150°C, specifically 60°C to 120°C, may be supplied and circulated under conditions of a pressure of 1 bar to 20 bar, specifically 2 bar to 10 bar, and a flow rate of 1 ton / hr to 10,000 ton / hr, specifically 10 ton / hr to 1,000 ton / hr. In addition, a high-temperature process fluid stream (10) supplied from a waste heat source is introduced into the evaporator (200) through which the boiler feedwater flows, thereby vaporizing the boiler feedwater (BFW) through heat exchange.

[0049] The initial temperature of the process fluid stream (10) flowing into the evaporator (200) (i.e., the temperature of the waste heat source) may be 50°C to 250°C, specifically 70°C to 200°C. When a high-temperature gaseous process fluid stream (10) supplied from a waste heat source flows into the evaporator (200), the boiler feedwater (BFW) may absorb heat from the process fluid stream and be vaporized through mutual heat exchange. At this time, in order to generate steam while maintaining the temperature difference with the process waste heat within an appropriate range, it is preferable to control the temperature difference between the boiler feedwater (BFW) and the waste heat source to 5°C to 30°C, specifically 5°C to 20°C.

[0050] In addition, the flow rate of the process fluid stream (10) flowing into the evaporator (200) is not particularly limited, but may be, for example, 1 Ton / hr to 10,000 Ton / hr, specifically 5 Ton / hr to 5,000 Ton / hr, and more specifically 5 Ton / hr to 1,000 Ton / hr. The process fluid that has exchanged heat with boiler feed water (BFW) in the evaporator (200) may flow out of the evaporator (200) at a temperature lower than the initial temperature, for example, in the range of 50°C to 200°C. At this time, as the temperature of the process fluid is lowered due to the heat exchange, it may be converted into a vapor-liquid two-phase.

[0051] According to one embodiment of the present invention, the first condenser (310) may be connected to the evaporator (200) via a first pipe, and the second condenser (320) may be connected to a second pipe branched from the first pipe. In addition, the first and second pipes may each be provided with openable valves (31, 32), which may be opened and closed depending on the phase of the process fluid stream discharged from the evaporator.

[0052] Typically, petrochemical plants operate multiple heat exchangers to cool or condense high-temperature process fluids generated in various process columns, while simultaneously recovering heat. During this process, some or all of the recovered process fluid is condensed for reuse within the process and then refluxed back into the columns. However, the heat recovery process presents a safety risk due to the phase change conditions of the process fluid entering the heat exchanger, such as the condenser.

[0053] As shown in Fig. 3, depending on whether the evaporator (200) is operated, a phase change occurs in the process fluid stream flowing into the condenser (300), and accordingly, a single condenser (300) must respond to a wide range of heat difference from a gaseous stream to a two-phase stream, thereby expanding the operating range of the condenser. Generally, a condenser is designed and manufactured based on the case where the heat exchange amount is the largest, but if the conditions of the process fluid stream flowing into the condenser (300) change significantly and the heat exchange amount also changes significantly, problems may occur in the thermal and mechanical performance of the heat exchanger. In particular, if the heat amount of the process fluid flowing into the condenser decreases, the flow rate of the refrigerant (CW) must also decrease.

[0054] For example, based on 100% of the total heat amount (i.e., heat exchange amount) condensed in the top discharge stream (10) of the gas phase, the heat exchange amount for condensing the two-phase stream in the condenser when generating steam can be reduced to 20% to 70%, and accordingly, the mass flow rate of the refrigerant can also be reduced proportionally. However, in this case, there is a problem that fouling phenomenon increases rapidly due to the slow flow rate, and if the refrigerant flow rate is increased to alleviate the fouling phenomenon, the temperature of the process fluid stream (13') becomes too low and cannot be controlled within the desired temperature range. That is, in order to improve process stability, a process fluid treatment system is required that can inject the process fluid into the condenser that is optimally designed according to the state of the process fluid, even if the heat exchange amount and operating conditions of the condenser (300) change depending on whether the evaporator (200) is operated.

[0055] Accordingly, in the present invention, an evaporator is connected to a waste heat source to cool or condense a high-temperature process fluid to recover heat, and boiler feed water is vaporized using the recovered heat to generate steam. At this time, two heat exchangers (condensers) having different heat exchange capacities are respectively provided and operated so as to respond to the state (phase) of the process fluid that changes depending on whether the evaporator is in operation, thereby improving process stability.

[0056] For example, when the process fluid stream discharged from the evaporator (200) is a two-phase stream including a vapor phase and a liquid phase, as illustrated in FIG. 1, the valve (31) of the first pipe may be opened and the valve (32) of the second pipe may be closed. Accordingly, the process fluid stream (11) converted to two phases may be discharged to the rear end of the evaporator (200) and transferred only to the first condenser (310). That is, the first condenser (310) may be operated, and the second condenser (320) may be stopped.

[0057] Specifically, when steam (20) is generated in the evaporator (200), the process fluid is converted into two phases due to heat exchange with boiler feed water (BFW), and the two-phase process fluid stream (11) discharged from the evaporator (200) can be supplied to the first condenser (310) and condensed and cooled by heat exchange with the refrigerant (CW1).

[0058] At this time, the temperature of the two-phase process fluid stream (11) flowing into the first condenser (310) may be 50°C to 200°C, specifically 60°C to 180°C, and the temperature of the condensed process fluid stream (13) discharged from the first condenser (310) may be 20°C to 150°C, specifically 20°C to 100°C.

[0059] In addition, as the refrigerant (CW1) of the first condenser (310), cooling water of, for example, 10°C to 50°C, specifically 20°C to 40°C, can be supplied and circulated under conditions of pressure of 1 bar to 20 bar, specifically 2 bar to 10 bar, and flow rate of 1 Ton / hr to 1,000,000 Ton / hr, specifically 1 Ton / hr to 100,000 Ton / hr.

[0060] As another example, when the process fluid stream discharged from the evaporator (200) is a gaseous stream, as illustrated in FIG. 2, the valve (31) of the first pipe may be closed and the valve (32) of the second pipe may be opened. Accordingly, the gaseous process fluid stream (12) may be discharged to the rear end of the evaporator (200) and transferred to the second condenser (320). That is, the first condenser (310) may be stopped from operating, and the second condenser (320) may be operated.

[0061] Specifically, when steam (20) is not generated in the evaporator (200), the process fluid is not heat-exchanged with boiler feed water (BFW) and is thus transferred in a vapor state without phase conversion, and the gaseous process fluid stream (12) discharged from the evaporator (200) is supplied to the second condenser (320) and can be condensed and cooled by heat-exchanging with the refrigerant (CW2).

[0062] At this time, the temperature of the gaseous process fluid stream (12) flowing into the second condenser (320) may be 50°C to 250°C, specifically 70°C to 200°C, and the temperature of the condensed process fluid stream (14) discharged from the second condenser (320) may be 20°C to 150°C, specifically 20°C to 100°C.

[0063] In addition, as the refrigerant (CW2) of the second condenser (320), cooling water of, for example, 10°C to 50°C, specifically 20°C to 40°C, can be supplied and circulated under conditions of pressure of 1 bar to 20 bar, specifically 2 bar to 10 bar, and flow rate of 1 Ton / hr to 1,000,000 Ton / hr, specifically 1 Ton / hr to 100,000 Ton / hr.

[0064] Specifically, the first condenser (310) has a smaller heat exchange capacity than the second condenser (320), thereby minimizing temperature fluctuations inside the condenser drum (350) described later, regardless of whether steam is generated, thereby improving process stability.

[0065] The heat exchange capacity of the second condenser relative to the heat exchange capacity of the first condenser may be 1:1.1 to 1:5.5, specifically 1:2 to 1:5.5. For example, when the heat exchange capacity of the condenser for condensing the entire gaseous column top discharge stream (10) is 100%, the heat exchange capacity of the first condenser (310) may be 20% to 70%, specifically 20% to 40%, and the heat exchange capacity of the second condenser (320) may be 80% to 110%, specifically 90% to 110%. In the process fluid treatment system according to the present invention, each condenser (310, 320) may be optimally designed based on the heat exchange capacity corresponding to the process fluid phase, which varies depending on whether steam is generated in the evaporator. Accordingly, the process can be operated stably regardless of whether steam is generated through waste heat recovery without thermal / mechanical performance problems of each condenser.

[0066] The condenser (310, 320) provided at the rear end of the above evaporator (200) is a type of heat exchanger commonly used in petrochemical processes, and the condenser applicable to the present invention may be a shell and tube type, and a plate type or a falling film evaporator type may also be used to increase heat exchange efficiency, but is not limited thereto.

[0067] The process fluid treatment system according to the present invention includes a condenser drum (350) for collecting a liquid process fluid. The condenser drum (350) is connected to a first condenser (310) and a second condenser (320) through pipes, respectively, and is supplied with a liquid process fluid stream (12, 14) discharged from the first condenser (310) and / or the second condenser (320), respectively.

[0068] For example, as illustrated in FIG. 1, a two-phase vapor-liquid process fluid stream (11) discharged when generating steam (20) in the evaporator (200) is supplied to a first condenser (310) for condensation and cooling, and the condensed and cooled liquid process fluid stream (13) discharged from the first condenser (310) can be transferred to a condenser drum (350). Here, since the gaseous process fluid stream (10) discharged to the top of the column (100) is partially condensed when generating steam in the evaporator (200), the amount of heat required for condensing the process fluid in the condenser is reduced. In the process fluid treatment system according to one embodiment of the present invention, only the two-phase vapor-liquid process fluid stream (11) can be supplied to the first condenser (310), and thus, a condenser designed with an optimal heat exchange capacity for the two-phase vapor-liquid process fluid stream (11) can be used, enabling more stable process operation. If a condenser with a large heat exchange capacity is used as the second condenser (320) that condenses the vapor state process fluid stream with the first condenser (310), the heat exchange capacity may be excessively large compared to the required amount of heat, which may cause problems in thermal and mechanical performance, and in particular, it may be difficult to control the internal temperature of the condenser drum.

[0069] As another example, as illustrated in FIG. 2, the gaseous process fluid stream (12) discharged from the evaporator (200) when steam (20) is not generated is supplied to the second condenser (320) for condensation and cooling, and the condensed and cooled liquid process fluid stream (13) discharged from the second condenser (320) can be transferred to the condenser drum (350). Here, the gaseous process fluid stream (10) discharged to the top of the column (100) when steam is not generated is not condensed in the evaporator (200) but is supplied to the second condenser (320) in a vapor state as is, so that a condenser designed with an optimal heat exchange capacity required for condensing it can be used, enabling more stable process operation. If a condenser with a small heat exchange capacity, such as the first condenser (310) that condenses the two-phase process fluid stream of vapor-liquid into the second condenser (320), is used, the heat exchange capacity may be small compared to the required amount of heat, making sufficient condensation of the process fluid impossible.

[0070] In this way, when each phase-dedicated condenser (310, 320) is provided at the rear end of the evaporator (200), by selectively operating each condenser depending on whether steam is generated in the evaporator (200), i.e., whether heat exchange is performed, the temperature change of the process fluid collected in the condenser drum (350) can be minimized, thereby ensuring operational stability.

[0071] The internal temperature of the condenser drum (350) may vary depending on the characteristics of the process, and may be maintained at, for example, 20°C to 150°C, specifically 30°C to 100°C, and more specifically 40°C to 80°C, but is not limited thereto. Since the inside of the condenser drum is in a normal state, the temperature is the same at any location under the same operating conditions.

[0072] In addition, the inside of the condenser drum (350) can maintain a temperature difference of 5°C or less, specifically 3°C or less, and more specifically 2°C or less. Here, the temperature difference inside the condenser drum refers to the temperature difference inside the condenser drum that changes depending on whether steam is generated in the evaporator. By maintaining a small temperature difference in the condenser drum (350) within the above temperature range, the process can be operated under optimal operating conditions while maintaining process stability. Furthermore, if the internal temperature difference of the condenser drum increases, the reflux ratio of the process fluid may decrease, the separation and purification efficiency in the column and the purity of the product may deteriorate, and the change in the vapor mass fraction of the process fluid may affect the subsequent process.

[0073] According to one embodiment of the present invention, the lower part of the condenser drum (350) is connected to the waste heat source, so that the liquid process fluid collected in the condenser drum can be refluxed.

[0074] More specifically, the lower part of the condenser drum (350) is connected to the column (100) by a pipe, so that the liquid process fluid collected in the condenser drum (350) can be refluxed to the column (100) where the waste heat source is generated as the lower discharge stream (15) of the condenser drum for reuse of the process fluid, or can be supplied to a subsequent process such as a reaction process or a purification process. Meanwhile, the upper discharge stream (16) of the condenser drum (350) can be input to a subsequent process such as a reaction process or a purification process, or can be discharged to the outside, but is not limited thereto.

[0075] According to one embodiment of the present invention, when necessary for processing process fluid, additional devices necessary for processing process fluid, such as valves, condensers, reboilers, pumps, separators, compressors, and mixers, may be installed.

[0076] Above, the process fluid treatment system according to the present invention has been described and illustrated in the drawings, but the description and illustration in the drawings describe and illustrate only the core components for understanding the present invention, and in addition to the processes and devices described and illustrated in the drawings, processes and devices not described and illustrated separately can be appropriately applied and utilized to implement the process fluid treatment system according to the present invention.

[0077] Hereinafter, the present invention will be described in more detail through examples. However, the following examples are intended to further illustrate the present invention, and the scope of the present invention is not limited by the following examples.

[0078] [Example]

[0079] (1) Example 1

[0080] Example 1-1

[0081] As illustrated in FIG. 1, waste heat recovery and process fluid treatment were performed using a process fluid treatment system in which a column (100), an evaporator (200), a first condenser (310), a second condenser (320), and a condenser drum (350) are connected. Specifically, in the process fluid treatment system, the first condenser (310) was connected to the evaporator (200) through a first pipe, the second condenser (320) was connected to a second pipe branched from the first pipe, and the first pipe and the second pipe were each provided with openable valves (31, 32).

[0082] First, a process fluid stream (10) in a vapor state (110°C and 1.5 bar) discharged to the top of the column (100) as a heat source was supplied to the evaporator (200) at a flow rate of 150 ton / hr, and also, boiler feed water (BFW) at 90°C was supplied under a pressure condition of 3 bar to exchange heat with the process fluid stream (10) to generate steam.

[0083] In addition, the valve (31) of the first pipe was opened, and the valve (32) of the second pipe was closed, so that the heat-exchanged process fluid stream (11) was discharged from the evaporator (200) through the first pipe in a vapor and liquid state (102°C and 1.45 bar) and supplied to the first condenser (310).

[0084] Thereafter, cooling water at 32°C and 5 bar was supplied as a refrigerant to the first condenser (310) at a flow rate of 550 ton / hr to perform heat exchange with the process fluid stream (11). Accordingly, the process fluid stream was condensed and cooled and discharged at 70°C.

[0085] Next, the 70°C process fluid stream (13) discharged from the first condenser (310) was supplied to the condenser drum (350). At this time, the inside of the condenser drum (350) was 70°C and 1.3 bar, and the mass fraction of vapor among the entire process fluid collected inside the condenser drum (350) was 0.05 (i.e., 5 wt% of vapor among the total 100 wt%).

[0086] Thereafter, the gaseous process fluid collected inside the condenser drum (350) was discharged to the upper discharge stream (16) of the condenser drum and supplied as feed to the subsequent reaction process, and the liquid process fluid was discharged to the lower discharge stream (15) of the condenser drum and refluxed to the column (100).

[0087] Example 1-2

[0088] Using the same system as in Example 1-1 above, but boiler feed water (BFW) was not supplied to the evaporator (200), so that no steam was generated, and as shown in FIG. 2, the valve (31) of the first pipe was closed, the valve (32) of the second pipe was opened, and the process fluid stream (12) discharged from the evaporator (200) in a 100 wt% vapor state (110°C and 1.5 bar) through the second pipe was supplied to the second condenser (320).

[0089] In addition, cooling water of 32°C and 5 bar was supplied as a refrigerant to the second condenser (300) at a flow rate of 1,780 ton / hr to perform heat exchange, and then a process fluid stream of 70°C was supplied to the condenser drum (350). At this time, the inside of the condenser drum (350) was 70°C and 1.3 bar, and the mass fraction of vapor among the entire process fluid collected inside the condenser drum (350) was 0.05 (i.e., 5 wt% of vapor among 100 wt% of the entire process fluid).

[0090] Thereafter, the gaseous process fluid collected inside the condenser drum (350) was discharged to the upper discharge stream (16) of the condenser drum and supplied as feed to the subsequent reaction process, and the liquid process fluid was discharged to the lower discharge stream (15) of the condenser drum and refluxed to the column (100).

[0091] (2) Comparative Example 1

[0092] Comparative Example 1-1

[0093] As shown in Fig. 3, waste heat recovery and process fluid treatment were performed using a process fluid treatment system in which a column (100), an evaporator (200), a condenser (300), and a condenser drum (350) are connected.

[0094] First, a gaseous (110°C and 1.5 bar) process fluid stream (10) discharged from the top of the column (100) as a heat source was supplied to the evaporator (200) at a flow rate of 150 ton / hr, and also, boiler feed water (BFW) at 90°C was supplied under a pressure condition of 3 bar to exchange heat with the process fluid stream (10) to generate steam.

[0095] The heat-exchanged process fluid stream (11') was discharged in a mixed vapor and liquid state (102°C and 1.45 bar) and supplied entirely to the condenser (300). In addition, cooling water at 32°C and 5 bar was supplied as a refrigerant to the condenser (300) at a flow rate of 550 ton / hr, thereby performing heat exchange with the two-phase process fluid stream (11') of vapor and liquid. Accordingly, the process fluid stream was condensed and cooled and discharged at 70°C.

[0096] Next, the 70°C process fluid stream (13') discharged from the condenser (300) was supplied to the condenser drum (350). At this time, the inside of the condenser drum (350) was 70°C and 1.3 bar, and the mass fraction of vapor among the entire process fluid collected inside the condenser drum (350) was 0.05 (i.e., 5 wt% of vapor among the total 100 wt%).

[0097] Thereafter, the gaseous process fluid collected inside the condenser drum (350) was discharged to the upper discharge stream (16) of the condenser drum and supplied as feed to the subsequent reaction process, and the liquid process fluid was discharged to the lower discharge stream (15) of the condenser drum and refluxed to the column (100).

[0098] Comparative Example 1-2

[0099] The same process as in Comparative Example 1-1 was performed, but boiler feed water (BFW) was not supplied to the evaporator (200), so steam was not generated, and the process fluid was also discharged from the evaporator (200) in a 100 wt% vapor state (110°C and 1.45 bar; 11') and supplied to the condenser (300). In addition, cooling water at 32°C and 5 bar was supplied as a refrigerant to the condenser (300) at a flow rate of 1,780 ton / hr to perform heat exchange, and then the 70°C process fluid stream (13') was supplied to the condenser drum (350). At this time, the inside of the condenser drum (350) was 70°C and 1.3 bar, and the mass fraction of the vapor among the entire process fluid collected inside the condenser drum (350) was 0.05 (i.e., 5 wt% of the total 100 wt% of the vapor).

[0100] Thereafter, the gaseous process fluid collected inside the condenser drum (350) was discharged to the upper discharge stream (16) of the condenser drum and supplied as feed to the subsequent reaction process, and the liquid process fluid was discharged to the lower discharge stream (15) of the condenser drum and refluxed to the column (100).

[0101] Comparative Example 1-3

[0102] The same process as in Comparative Example 1-1 was performed, but cooling water at 32°C and 5 bar was supplied as a refrigerant to the condenser (300) at a flow rate of 1,780 ton / hr to perform heat exchange with a two-phase process fluid stream (11') of vapor and liquid, and then a process fluid stream (13') at 42°C was supplied to the condenser drum (350). At this time, the inside of the condenser drum (350) was 45°C and 1.3 bar, and the mass fraction of vapor among the entire process fluid collected inside the condenser drum (350) was 0 (i.e., 0 wt% of vapor among the total 100 wt%).

[0103] Afterwards, the liquid process fluid collected inside the condenser drum (350) was discharged to the lower discharge stream (15) of the condenser drum and refluxed to the column (100), and no gaseous process fluid was generated, so it could not be supplied as feed to the subsequent reaction process.

[0104] (3) Experimental example

[0105] Table 1 below shows the status, temperature, and heat amount of the process fluid in each device according to whether steam is generated in the process fluid treatment systems according to the above examples and comparative examples.

[0106] Specifically, the heat utilization rate of the condenser (300, 310, 320) was compared with the heat utilization rate of the condenser for the gaseous process fluid stream as 100% when steam is not generated, i.e., when boiler feedwater is not supplied to the evaporator, as in Example 1-2 and Comparative Example 1-2. For example, in Table 1 below, a heat utilization rate of 30% of the condenser means that 70% of the heat was used in the evaporator and 30% of the heat was used in the condenser.

[0107] In addition, the refrigerant flow rate ratio of the condenser (300, 310, 320) was compared based on the mass flow rate of the refrigerant supplied to the condenser when no steam was generated, as in Example 1-2 and Comparative Example 1-2, as 100%.

[0108] Meanwhile, the heat exchange capacity of the condenser is typically designed to have a margin of approximately 20% relative to the maximum required heat exchange capacity of 100%. Accordingly, the heat utilization rate relative to the design capacity of the condenser (300, 310, 320) was calculated based on 120% of the design capacity of the condenser (300, 310, 320).

[0109] In addition, when the heat utilization rate compared to the condenser design capacity fell below 50%, the heat exchange efficiency was drastically reduced, and fouling increased due to the reduction in refrigerant flow rate. Accordingly, the operating stability of the condenser (300, 310, 320) was judged to be excellent when the heat utilization rate compared to the condenser design capacity exceeded 50%, and was marked as “O”. When the heat utilization rate compared to the condenser design capacity was below 50%, the operating stability was judged to be poor, and was marked as “X”.

[0110] Furthermore, if the temperature deviation inside the condenser drum is less than 5℃ depending on whether steam is generated, the temperature control is judged to be successful and “O” is recorded, and if the temperature deviation inside the condenser drum is more than 5℃, the temperature control is judged to have failed and “X” is recorded.

[0111] In addition, if there is no change in the mass fraction of steam inside the condenser drum (350) depending on whether steam is generated, the stability of the subsequent process is judged to be excellent and “O” is recorded, and if there is a change in the mass fraction of steam inside the condenser drum (350), the stability of the subsequent process is judged to be deteriorated and “X” is recorded.

[0112] Device Type Item Example 1 Comparative Example 1 (Fig. 3) 1-1 (Fig. 1) 1-2 (Fig. 2) 1-1 1-2 1-3 Evaporator (200) Steam generation OXOXO Discharge process fluid stream Above / Liquid device / Liquid device / Liquid Condenser (300, 310, 320) Heat utilization rate 30% 100% 30% 100% 65% Refrigerant flow rate ratio 31% 100% 31% 100% 100% Heat utilization rate compared to design capacity 83% 83% 25% 83% 54% Operational stability OOXOO Discharge process fluid stream temperature 70℃ 70℃ 70℃ 70℃ 42℃ Condenser drum (350) Internal temperature 70℃ 70℃ 70℃ 70℃ 42℃ Temperature control OOOOX Vapor mass fraction 5% 5% 5% 0% Downstream process stability OOOOX

[0113] As can be seen in Table 1 above, the process fluid treatment system according to the present invention can not only ensure the operation stability of the condenser by switching the operation of the first condenser (310) and the second condenser (320) with different heat exchange capacities depending on whether steam is generated in the evaporator (200), but also control the internal temperature and vapor mass fraction in the condenser drum (350), thereby ensuring the stability of the subsequent process.

[0114] On the other hand, as in the comparative example, when the process fluid stream discharged from the evaporator (200) is processed using only one condenser (300), problems occur in the operating stability of the condenser (300) or in the control of the internal temperature and vapor mass fraction of the condenser drum (350).

[0115] Specifically, in Comparative Example 1, a process fluid system equipped with only one condenser (300) used a condenser designed with the same heat exchange capacity as the second condenser (320) of Example 1 so that it could cope even when the evaporator (200) was not in operation. However, when steam was generated in the evaporator (200) as in Comparative Example 1-1, the heat utilization rate was too low compared to the design capacity of the condenser (300), so that the heat exchange efficiency was rapidly reduced, and furthermore, fouling increased due to a decrease in the flow rate of the refrigerant, causing a problem with the stability of the condenser.

[0116] Meanwhile, in order to solve this problem, when the flow rate of the refrigerant was not reduced as in Comparative Example 1-3 and the same flow rate as in Comparative Example 1-2 was maintained, the heat exchange amount was excessive and the condenser heat utilization rate increased to 65%, and accordingly, the internal temperature of the condenser drum (350) dropped to 42℃ due to excessive cooling of the process fluid. Furthermore, the internal temperature of the condenser drum (350) became too low and the gaseous process fluid was not collected, and thus the feed could not be supplied to the reaction process at the rear end of the condenser drum. Through this, it was confirmed that if the internal temperature of the condenser drum (350) is not controlled, the upper discharge stream (16) of the condenser drum cannot be supplied consistently to the rear end process, resulting in a deterioration in the stability of the rear end process.

[0117] Although exemplary embodiments of the present invention have been described above, the present invention is not limited thereto, and those skilled in the art will understand that various changes and modifications are possible within the scope and spirit of the claims set forth below.

[0118] [Explanation of symbols]

[0119] 100: Column

[0120] 200: Evaporator

[0121] 250: Pressurization system

[0122] 300, 310, 320: Condenser

[0123] 350: Condenser drum

[0124] 31, 32: Valve

[0125] 10, 11, 11', 12, 13, 13', 14, 15, 16: Process fluid streams

[0126] 20: Steam

[0127] BFW: Boiler feedwater

[0128] CW, CW1, CW2: Refrigerant

Claims

1. In a process of recovering waste heat from process fluid, An evaporator that generates steam using a gaseous process fluid stream supplied from a waste heat source as a heat source; A first condenser and a second condenser that receive the process fluid stream discharged from the above evaporator and cool it by heat exchange with a refrigerant; and A condenser drum, each connected to the first condenser and the second condenser by a pipe; The above evaporator and the first condenser are connected through a first pipe, The above second condenser is connected to a second pipe branched from the first pipe, A process fluid treatment system, wherein the first and second pipes are each provided with an openable valve, which is opened and closed according to the phase of the process fluid stream discharged from the evaporator.

2. In paragraph 1, A process fluid treatment system, wherein the first condenser has a smaller heat exchange capacity than the second condenser.

3. In paragraph 1, A process fluid treatment system, wherein the heat exchange capacity of the second condenser is 1:1.1 to 1:5.5 compared to the heat exchange capacity of the first condenser.

4. In paragraph 1, A process fluid treatment system comprising: introducing boiler feedwater into the evaporator to exchange heat with the process fluid stream of the above-mentioned phase to generate steam; and recovering waste heat through the steam.

5. In paragraph 1, A process fluid treatment system, wherein when the process fluid stream discharged from the evaporator is a two-phase stream including a gas phase and a liquid phase, the valve of the first pipe is opened and the valve of the second pipe is closed.

6. In paragraph 1, A process fluid treatment system, wherein when the process fluid stream discharged from the above evaporator is a gaseous stream, the valve of the first pipe is closed and the valve of the second pipe is opened.

7. In paragraph 1, A process fluid treatment system further comprising a pressurization system connected to the evaporator to increase the pressure of the steam.

8. In paragraph 7, A process fluid treatment system, wherein the pressurization system is selected from a mechanical vapor recompression (MVR) system and a thermal vapor recompression (TVR) system.

9. In paragraph 1, A process fluid treatment system, wherein the initial temperature of the process fluid stream flowing into the above evaporator is 50°C to 250°C.

10. In paragraph 1, A process fluid treatment system in which the internal temperature of the above condenser drum is maintained with a temperature difference of 5℃ or less.

11. In paragraph 1, A process fluid treatment system, wherein the lower portion of the condenser drum is connected to the waste heat source and includes refluxing the liquid process fluid collected in the condenser drum.

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