Pre-cooling heat exchange system

Abstract

The utility model discloses a pre-cooling heat exchange system which comprises a heat exchanger, a first inlet, a first outlet, a second inlet and a second outlet are formed in the outer wall of the heat exchanger, a first channel and a second channel are arranged in the heat exchanger, the first inlet and the first outlet are both communicated with the first channel, and the second inlet and the second outlet are both communicated with the second channel; the fluid switching mechanism is used for switching fluid in the first channel and the second channel, in the first state, the first channel is used for introducing hot fluid, and the second channel is used for introducing cold fluid; and in the second state, the first channel is used for introducing cold fluid, and the second channel is used for introducing hot fluid. According to the utility model, the scaling rate of the pre-heater / pre-cooler can be delayed, and the system energy consumption is saved.

Description

Technical Field

[0001] The utility model relates to the field of heat exchangers, and particularly to a precooling heat exchange system. Background Art

[0002] In an evaporation crystallization system, the conditions of crystallization and scaling of a preheater / precooler often occur. At this time, the heat exchange efficiency is greatly reduced, increasing the steam consumption or cold energy consumption of the system.

[0003] For example, in a sodium chloride or sodium sulfate evaporation crystallization system, preheating is usually carried out by condensate or concentrated liquid. During the preheating process, as the feed liquid is heated, the solubility of calcium sulfate and the like decreases, and it will gradually precipitate, slowly reducing the heat exchange efficiency and even causing fouling and blockage of the preheater. Summary of the Utility Model

[0004] The purpose of the utility model is to solve the problems of low heat exchange efficiency caused by crystallization and scaling of the precooler / preheater, and large steam consumption or cold energy consumption of the system. The utility model provides a precooling heat exchange system, which can delay the scaling rate of the preheater / precooler and save the energy consumption of the system.

[0005] To solve the above technical problems, an embodiment of the utility model discloses a precooling heat exchange system, including:

[0006] A heat exchanger, the outer wall of the heat exchanger is provided with a first inlet, a first outlet, a second inlet and a second outlet, the inside of the heat exchanger is provided with a first channel and a second channel, the first inlet and the first outlet are both communicated with the first channel, and the second inlet and the second outlet are both communicated with the second channel;

[0007] A fluid conversion mechanism, the fluid conversion mechanism is used to switch the fluids in the first channel and the second channel, wherein,

[0008] In the first state, the first channel is used for introducing a hot fluid, and the second channel is used for introducing a cold fluid;

[0009] In the second state, the first channel is used for introducing a cold fluid, and the second channel is used for introducing a hot fluid.

[0010] With the above technical solution, in the first state, the hot fluid is introduced into the first channel, and the cold fluid is introduced into the second channel. The hot fluid and the cold fluid exchange heat to preheat the cold fluid. At this time, the solubility of some impurities in the cold fluid will decrease after the temperature rises, resulting in supersaturation of the impurities, causing the impurities to gradually precipitate, leading to crystallization in the second channel, and ultimately causing fouling of the second channel. Therefore, by setting a fluid conversion mechanism, when crystals precipitate in the second channel, the fluid conversion mechanism is opened, so that the cold fluid flows through the first channel and the hot fluid flows through the second channel. At this time, the cold fluid in the first channel and the hot fluid in the second channel can still achieve heat exchange. At the same time, the hot fluid in the second channel dissolves the impurities precipitated by the cold fluid in the first state, making the second channel clean without crystallized crystals, maintaining the heat exchange efficiency between the cold fluid and the hot fluid, delaying the scaling rate of the preheater / precooler, and saving system energy consumption.

[0011] According to another specific embodiment of the present invention, an embodiment of the present invention discloses a precooling heat exchange system, and the heat exchanger is a plate heat exchanger.

[0012] According to another specific embodiment of the present invention, an embodiment of the present invention discloses a precooling heat exchange system, and the heat exchanger is a tubular heat exchanger.

[0013] According to another specific embodiment of the present invention, an embodiment of the present invention discloses a precooling heat exchange system. The fluid conversion mechanism includes a plurality of pipes. The plurality of pipes include a first pipe, a second pipe, a third pipe, a fourth pipe, a fifth pipe, a sixth pipe, a seventh pipe, and an eighth pipe. Among them, the first pipe and the second pipe are connected in parallel and communicate with the first inlet, the third pipe and the fourth pipe are connected in parallel and communicate with the second inlet, the fifth pipe and the sixth pipe are connected in parallel and communicate with the first outlet, and the seventh pipe and the eighth pipe are connected in parallel and communicate with the second outlet; among them,

[0014] In the first state, the hot fluid flows through the first pipe, the first channel, and the fifth pipe respectively, and the cold fluid flows through the fourth pipe, the second channel, and the eighth pipe respectively;

[0015] In the second state, the hot fluid flows through the third pipe, the second channel, and the seventh pipe respectively; the cold fluid flows through the second pipe, the first channel, and the sixth pipe respectively.

[0016] With the above technical solution, in the first state, the first state can be a precooling state or a preheating state. When it is in the precooling state, the hot fluid is the target fluid, and when it is in the preheating state, the cold fluid is the target fluid.

[0017] Taking the preheating state as an example for illustration, the hot fluid flows through the first pipeline to the first inlet, and then enters the first channel from the first inlet. The cold fluid flows through the fourth pipeline to the second inlet, and then flows to the second channel from the second inlet. At this time, the hot fluid in the first channel and the cold fluid in the second channel conduct heat exchange. Specifically, the cold fluid in the second channel is preheated. After the heat exchange is completed, the hot fluid then flows from the first outlet to the fifth pipeline, and the cold fluid then flows from the second outlet to the eighth pipeline. During the preheating process, the solubility of some impurities in the cold fluid will decrease after the temperature rises, resulting in supersaturation of the impurities, causing the impurities to gradually precipitate, resulting in crystallization in the second channel, and ultimately causing fouling of the second channel.

[0018] When crystals precipitate in the second channel, the fluid conversion mechanism is opened to make the cold fluid flow through the first channel and the hot fluid flow through the second channel, that is, it is converted from the first state to the second state. Specifically, the hot fluid flows through the third pipeline to the second inlet, and then enters the second channel from the second inlet. The cold fluid flows through the second pipeline to the first inlet, and then flows to the first channel from the first inlet. At this time, the cold fluid in the first channel and the hot fluid in the second channel can still conduct heat exchange. Specifically, the cold fluid in the first channel is preheated. At the same time, the hot fluid in the second channel dissolves the impurities precipitated by the cold fluid in the first state. Since the solubility of this substance in the hot fluid is much lower than the saturation degree, when the hot fluid flows in the second channel, it can dissolve this substance (i.e., the impurities precipitated by the cold fluid) in the second channel, making the second channel clean without crystallized crystals, maintaining the heat exchange efficiency between the cold fluid and the hot fluid, delaying the fouling rate of the preheater / precooler, and saving system energy consumption. After the above fouling cleaning process is completed, the hot fluid then flows from the second outlet to the seventh pipeline, and the cold fluid then flows from the first outlet to the sixth pipeline.

[0019] Taking the precooling state as an example for illustration, the cold fluid flows through the second pipeline to the first inlet, and then enters the first channel from the first inlet. The hot fluid flows through the third pipeline to the second inlet, and then flows to the second channel from the second inlet. At this time, the cold fluid in the first channel and the hot fluid in the second channel conduct heat exchange. Specifically, the hot fluid in the second channel is precooled. After the heat exchange is completed, the cold fluid then flows from the first outlet to the fifth pipeline, and the hot fluid then flows from the second outlet to the seventh pipeline. During the precooling process, the solubility of some impurities in the cold fluid will decrease after the temperature rises, resulting in supersaturation of the impurities, causing the impurities to gradually precipitate, resulting in crystallization in the first channel, and ultimately causing fouling of the first channel.

[0020] When crystals precipitate in the first channel, the fluid conversion mechanism is opened so that the hot fluid flows through the first channel and the cold fluid flows through the second channel, that is, it is converted from the first state to the second state. Specifically, the cold fluid flows through the four pipes to the second inlet and then flows into the second channel from the second inlet. The hot fluid flows through the first pipe to the first inlet and then flows into the first channel from the first inlet. At this time, the hot fluid in the first channel and the cold fluid in the second channel can still exchange heat. Specifically, the hot fluid in the first channel is precooled. At the same time, the hot fluid in the first channel dissolves the impurities precipitated by the cold fluid in the first state. Since the solubility of this substance in the hot fluid is much lower than the saturation degree, when the hot fluid flows through the first channel, it can dissolve this substance (i.e., the impurities precipitated by the cold fluid) in the first channel, making the first channel clean without crystallized crystals, maintaining the heat exchange efficiency between the cold fluid and the hot fluid, delaying the scaling rate of the preheater / precooler, and saving the system energy consumption. After the above scaling cleaning process is completed, the cold fluid then flows from the second outlet to the eighth pipe, and the hot fluid then flows from the first outlet to the fifth pipe.

[0021] According to another specific embodiment of the present invention, an embodiment of the present invention discloses a precooling heat exchange system. The fluid conversion mechanism further includes a plurality of valves, and the valves include a first valve, a second valve, a third valve, a fourth valve, a fifth valve, a sixth valve, a seventh valve, and an eighth valve. The first valve is arranged on the first pipe, the second valve is arranged on the second pipe, the third valve is arranged on the seventh pipe, the fourth valve is arranged on the eighth pipe, the fifth valve is arranged on the fifth pipe, the sixth valve is arranged on the sixth pipe, the seventh valve is arranged on the seventh pipe, and the eighth valve is arranged on the eighth pipe.

[0022] Adopting the above technical solution, when in the first state, taking the preheating state at this time as an example for explanation, the first valve, the fourth valve, the fifth valve, and the eighth valve are opened so that the hot fluid can flow through the first pipe to the first inlet and then flow into the first channel from the first inlet. After the heat exchange is completed, the hot fluid then flows from the first outlet to the fifth pipe; similarly, the cold fluid can flow through the fourth pipe to the second inlet and then flow into the second channel from the second inlet. After the heat exchange is completed, the cold fluid then flows from the second outlet to the eighth pipe to achieve the above precooling process.

[0023] In the second state, the second valve, the third valve, the sixth valve, and the seventh valve are opened, enabling the hot fluid to flow through the third pipeline to the second inlet, and then into the second channel from the second inlet. After the crystals in the second channel are dissolved, the hot fluid then flows from the second outlet to the seventh pipeline. Similarly, the cold fluid can flow through the second pipeline to the first inlet, and then from the first inlet to the first channel. After the crystals in the second channel are dissolved, the cold fluid then flows from the first outlet to the sixth pipeline, so as to realize the above-mentioned process of crystal dissolution, that is, the process of cleaning the scale on the second channel.

[0024] According to another specific embodiment of the present invention, an embodiment of the present invention discloses a precooling heat exchange system, wherein the first valve, the second valve, the third valve, the fourth valve, the fifth valve, the sixth valve, the seventh valve, and the eighth valve are all solenoid valves.

[0025] By adopting the above technical solution, by setting solenoid valves, the opening and closing time of the solenoid valves can be determined according to the properties of the incoming feed liquid. For example, if some feed liquid will crystallize in four hours, the solenoid valves can be set to open the first valve, the fourth valve, the fifth valve, and the eighth valve every four hours, and open the second valve, the third valve, the sixth valve, and the seventh valve every four hours, so as to realize the automatic cleaning of scale, maintain the heat exchange efficiency of the cold fluid and the hot fluid, delay the scale formation rate of the preheater / precooler, and save the system energy consumption.

[0026] According to another specific embodiment of the present invention, an embodiment of the present invention discloses a precooling heat exchange system, and a sewage discharge point is further provided on the heat exchanger. Along the axial direction, the sewage discharge point is arranged at the bottom end of the heat exchanger.

[0027] By adopting the above technical solution, during the operation of the heat exchanger, dirt, sediment, or corrosion products may be generated when the fluid flows inside, and these substances will reduce the heat exchange efficiency. The sewage discharge point can be used to discharge these impurities for cleaning and maintenance. Description of the Drawings

[0028] Figure 1 The structural schematic diagram of the precooling heat exchange system provided by the embodiment of the present invention is shown, wherein the heat exchanger is a plate heat exchanger;

[0029] Figure 2 The structural schematic diagram of the precooling heat exchange system provided by the embodiment of the present invention is shown, wherein the heat exchanger is a tubular heat exchanger.

[0030] Among them, the reference numerals: 100, plate heat exchanger; 101, tubular heat exchanger; 102, first inlet; 103, first outlet; 104, second inlet; 105, second outlet; 106, first channel; 107, second channel; 200, fluid conversion mechanism; 201, first pipeline; 202, second pipeline; 203, third pipeline; 204, fourth pipeline; 205, fifth pipeline; 206, sixth pipeline; 207, seventh pipeline; 208, eighth pipeline; 210, first valve; 211, second valve; 212, third valve; 213, fourth valve; 214, fifth valve; 215, sixth valve; 216, seventh valve; 217, eighth valve; 300, sewage discharge point; 301, sewage discharge valve; 302, sewage discharge pipeline; 400, first common pipeline; 401, second common pipeline; 402, third common pipeline; 403, fourth common pipeline; 404, fifth common pipeline; 405, sixth common pipeline; 406, seventh common pipeline; 407, eighth common pipeline. Detailed implementation manners

[0031] The following specific embodiments illustrate the implementation manners of the present utility model. Those skilled in the art can easily understand other advantages and effects of the present utility model from the content disclosed in this specification. Although the description of the present utility model will be introduced in conjunction with the preferred embodiments, this does not mean that the features of this utility model are limited to this implementation manner. On the contrary, the purpose of introducing the utility model in conjunction with the implementation manner is to cover other alternatives or modifications that may be extended based on the claims of the present utility model. In order to provide a deep understanding of the present utility model, many specific details will be included in the following description. The present utility model can also be implemented without these details. In addition, in order to avoid confusion or obscuring the key points of the present utility model, some specific details will be omitted in the description. It should be noted that, without conflict, the embodiments in the present utility model and the features in the embodiments can be combined with each other.

[0032] It should be noted that in this specification, similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0033] In the description of this embodiment, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "bottom", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the utility model product is usually placed during use. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present utility model.

[0034] The terms "first", "second", etc. are only used for distinguishing descriptions and should not be construed as indicating or implying relative importance.

[0035] In the description of this embodiment, it should also be noted that unless otherwise clearly specified and defined, the terms "set", "connected", and "connected to" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in this embodiment can be understood according to specific situations.

[0036] To make the objectives, technical solutions, and advantages of the present utility model clearer, the embodiments of the present utility model will be further described in detail below in conjunction with the accompanying drawings.

[0037] In an evaporation crystallization system, the working conditions of crystallization and scaling in the preheater / precooler are often encountered. At this time, the heat transfer efficiency drops significantly, increasing the steam consumption or cold energy consumption of the system.

[0038] For example, in a sodium chloride or sodium sulfate evaporation crystallization system with slightly higher inlet water hardness, condensate preheating of the feed or preheating of the concentrated liquid is generally designed. During the preheating process, as the feed liquid temperature rises, the solubility of calcium sulfate and other substances decreases, and they will gradually precipitate, slowly reducing the heat transfer efficiency and even causing fouling and blockage of the preheater.

[0039] For example, in a mirabilite crystallization system, a feed pre-cooler is generally designed to pre-cool the feed with mirabilite clear liquid. However, the mirabilite clear liquid comes from the overflow of the mirabilite thickener and actually contains a small amount of fine crystals. Theoretically, when the mirabilite clear liquid is heated in the pre-cooler and the solubility of the solution increases, the fine crystals will dissolve. But in the actual operation process, the mirabilite fine crystals first agglomerate and then slowly dissolve during the heating process, which will cause frequent blockage of the pre-cooler.

[0040] For this reason, with reference to Figure 1, an embodiment of the present application provides a precooling heat exchange system, including: a heat exchanger (including the plate heat exchanger 100 and the tubular heat exchanger 101 described below) and a fluid conversion mechanism 200. The outer wall of the heat exchanger is provided with a first inlet 102, a first outlet 103, a second inlet 104, and a second outlet 105. The interior of the heat exchanger is provided with a first channel 106 and a second channel 107. The first inlet 102 and the first outlet 103 are both connected to the first channel 106, and the second inlet 104 and the second outlet 105 are both connected to the second channel 107; the fluid conversion mechanism 200 is used to switch the fluids in the first channel 106 and the second channel 107. Among them, in the first state, the first channel 106 is used to introduce a hot fluid, and the second channel 107 is used to introduce a cold fluid; in the second state, the first channel 106 is used to introduce a cold fluid, and the second channel 107 is used to introduce a hot fluid.

[0041] With the above technical solution, in the first state, the hot fluid is introduced into the first channel 106, and the cold fluid is introduced into the second channel 107. The hot fluid and the cold fluid exchange heat to realize the preheating of the cold fluid. At this time, after the temperature of the cold fluid rises, the solubility of some impurities in the cold fluid will decrease, resulting in supersaturation of the impurities, causing the impurities to gradually precipitate, resulting in crystallization in the second channel 107, and finally causing fouling of the second channel 107. Therefore, by setting the fluid conversion mechanism 200, when crystals precipitate in the second channel 107, the fluid conversion mechanism 200 is opened, so that the cold fluid flows through the first channel 106 and the hot fluid flows through the second channel 107. At this time, the cold fluid in the first channel 106 and the hot fluid in the second channel 107 can still achieve heat exchange. At the same time, the hot fluid in the second channel 107 dissolves the impurities precipitated from the cold fluid in the first state, making the second channel 107 clean without crystalline crystals, maintaining the heat exchange efficiency of the cold fluid and the hot fluid, delaying the scaling rate of the preheater / precooler, and saving system energy consumption.

[0042] Exemplarily, the heat exchanger can be a plate heat exchanger 100 or a tubular heat exchanger 101, and the fluid conversion mechanism 200 includes a plurality of pipes and a plurality of valves.

[0043] Exemplarily, the multiple pipes include a first pipe 201, a second pipe 202, a third pipe 203, a fourth pipe 204, a fifth pipe 205, a sixth pipe 206, a seventh pipe 207, and an eighth pipe 208. Among them, the first pipe 201 and the second pipe 202 are in parallel and are connected to the first inlet 102 through a first common pipe 400. The third pipe 203 and the fourth pipe 204 are in parallel and are connected to the second inlet 104 through a second common pipe 401. The fifth pipe 205 and the sixth pipe 206 are in parallel and are connected to the first outlet 103 through a third common pipe 402. The seventh pipe 207 and the eighth pipe 208 are in parallel and are connected to the second outlet 105 through a fourth common pipe 403. Among them, in the first state, the hot fluid flows through the first pipe 201, the first channel 106, and the fifth pipe 205 respectively, and the cold fluid flows through the fourth pipe 204, the second channel 107, and the eighth pipe 208 respectively. In the second state, the hot fluid flows through the third pipe 203, the second channel 107, and the seventh pipe 207 respectively. The cold fluid flows through the second pipe 202, the first channel 106, and the sixth pipe 206 respectively.

[0044] Adopting the above technical solution, in the first state, the first state can be a pre-cooling state or a pre-heating state. When it is in the pre-cooling state, the hot fluid is the target fluid. When it is in the pre-heating state, the cold fluid is the target fluid.

[0045] Here, taking the pre-heating state as an example for elaboration, the hot fluid flows into from the fifth common pipe 404, is split and flows to the first pipe 201, then flows to the first common pipe 400, and thus flows to the first inlet 102. Then it flows into the first channel 106 from the first inlet 102. The cold fluid flows into from the eighth common pipe 407, is split and flows to the fourth pipe 204, then flows to the second common pipe 401, and thus flows to the second inlet 104. Then it flows from the second inlet 104 to the second channel 107. At this time, the hot fluid in the first channel 106 and the cold fluid in the second channel 107 perform heat exchange. Specifically, the cold fluid in the second channel 107 is pre-heated. When the heat exchange is completed, the hot fluid then flows from the first outlet 103 to the third common pipe 402, is split and flows to the fifth pipe 205, and finally flows out from the seventh common pipe 406. The cold fluid then flows from the second outlet 105 to the fourth common pipe 403 and is split and flows to the eighth pipe 208, and finally flows out from the sixth common pipe 405. During the pre-heating process, the solubility of some impurities in the cold fluid will decrease after the temperature rises, resulting in supersaturation of the impurities, causing the impurities to gradually precipitate, resulting in crystallization in the second channel 107, and finally causing fouling and blockage of the second channel 107.

[0046] When crystals precipitate in the second channel 107, the fluid conversion mechanism 200 is opened so that the cold fluid flows through the first channel 106 and the hot fluid flows through the second channel 107, that is, it is converted from the first state to the second state. Specifically, the hot fluid flows in from the fifth common pipe 404, is diverted to the third pipe 203, then flows from the second common pipe 401 to the second inlet 104, and then flows into the second channel 107 from the second inlet 104. The cold fluid flows in from the eighth common channel 407, is diverted to the second pipe 202, flows through the first common channel to the first inlet 102, and then flows from the first inlet 102 to the first channel 106. At this time, the cold fluid in the first channel 106 and the hot fluid in the second channel 107 can still exchange heat. Specifically, the cold fluid in the first channel 106 is preheated. At the same time, the hot fluid in the second channel 107 dissolves the impurities precipitated by the cold fluid in the first state. Since the solubility of this substance in the hot fluid is much lower than the saturation concentration, when the hot fluid flows in the second channel 107, it can dissolve this substance (i.e., the impurities precipitated by the cold fluid) in the second channel 107, making the second channel 107 clean without crystallized crystals, maintaining the heat exchange efficiency between the cold fluid and the hot fluid, delaying the fouling rate of the preheater / precooler, and saving the system energy consumption.

[0047] After the above fouling cleaning process is completed, the hot fluid then flows from the second outlet 105 to the fourth common channel 403, is diverted to the seventh pipe 207, and finally flows out from the seventh common channel 406; the cold fluid then flows from the first outlet 103 to the third common channel 402, is diverted to the sixth pipe 206, and finally flows out from the sixth common channel 407.

[0048] Exemplarily, the valves include a first valve 210, a second valve 211, a third valve 212, a fourth valve 213, a fifth valve 214, a sixth valve 215, a seventh valve 216, and an eighth valve 217. The first valve 210 is provided on the first pipe 201, the second valve 211 is provided on the second pipe 202, the third valve 212 is provided on the third pipe 203, the fourth valve 213 is provided on the fourth pipe 204, the fifth valve 214 is provided on the fifth pipe 205, the sixth valve 215 is provided on the sixth pipe 206, the seventh valve 216 is provided on the seventh pipe 207, and the eighth valve 217 is provided on the eighth pipe 208.

[0049] With the above technical solution, when in the first state, the first valve 210, the fourth valve 213, the fifth valve 214, and the eighth valve 217 are opened, enabling the hot fluid to flow through the first pipeline 201 to the first inlet 102, and then from the first inlet 102 into the first channel 106. After the heat exchange is completed, the hot fluid then flows from the first outlet 103 to the fifth pipeline 205; similarly, the cold fluid can flow through the fourth pipeline 204 to the second inlet 104, and then from the second inlet 104 to the second channel 107. After the heat exchange is completed, the cold fluid then flows from the second outlet 105 to the eighth pipeline 208 to achieve the above preheating process.

[0050] When in the second state, the second valve 211, the third valve 212, the sixth valve 215, and the seventh valve 216 are opened, enabling the hot fluid to flow through the third pipeline 203 to the second inlet 104, and then from the second inlet 104 into the second channel 107. After the crystals in the second channel 107 are dissolved, the hot fluid then flows from the second outlet 105 to the seventh pipeline 207; similarly, the cold fluid can flow through the second pipeline 202 to the first inlet 102, and then from the first inlet 102 to the first channel 106. After the crystals in the second channel 107 are dissolved, the cold fluid then flows from the first outlet 103 to the sixth pipeline 206 to achieve the above process of dissolving the crystals, that is, the process of cleaning the scale on the second channel 107.

[0051] Exemplarily, the first valve 210, the second valve 211, the third valve 212, the fourth valve 213, the fifth valve 214, the sixth valve 215, the seventh valve 216, and the eighth valve 217 are all solenoid valves, but are not limited thereto, and switch butterfly valves, switch ball valves, etc. can also be selected.

[0052] With the above technical solution, by setting solenoid valves, the opening and closing time of the solenoid valves can be determined according to the properties of the fed liquid. For example, if some liquid will crystallize in four hours, then the solenoid valves can be set to open the first valve 210, the fourth valve 213, the fifth valve 214, and the eighth valve 217 every four hours, and open the second valve 211, the third valve 212, the sixth valve 215, and the seventh valve 216 every four hours to achieve automatic cleaning of the scale, maintain the heat exchange efficiency of the cold fluid and the hot fluid, delay the scale formation rate of the preheater / precooler, and save the system energy consumption.

[0053] A sewage discharge point 300 is also provided on the heat exchanger, along the axial direction (i.e., Figure 1 the X direction shown), the sewage discharge point 300 is arranged at the bottom end of the heat exchanger. Among them, the number of sewage discharge points 300 in the embodiments of the present application is not limited, and it can be, for example, as Figure 1 and Figure 2The two shown may also be three or more. Specifically, sewage pipes 302 are respectively provided on the first common pipe 400 and the second common pipe 401, and a sewage valve 301 is provided on the sewage pipe 302. The sewage valve 301 can be an electromagnetic valve or a manual valve. During the operation of the heat exchanger, dirt, sediment or corrosion products may be generated when the fluid flows inside, and these substances will reduce the heat exchange efficiency. The sewage point 300 can be used to discharge these impurities for cleaning and maintenance.

[0054] In summary, based on the above scaling principle of the pre-cooling / pre-heating device, from a process perspective, the present application embodiment can set to switch the fluid conversion mechanism regularly. Specifically, the state can be switched regularly every 8 hours / 12 hours (following the operation shift time). That is to say, the first state is run every 8 hours / 12 hours, the first valve 210, the fourth valve 213, the fifth valve 214 and the eighth valve 217 are opened, and the second valve 211, the third valve 212, the sixth valve 215 and the seventh valve 216 are closed. The second state is run every 8 hours / 12 hours, the second valve 211, the third valve 212, the sixth valve 215 and the seventh valve 216 are opened, and the first valve 210, the fourth valve 213, the fifth valve 214 and the eighth valve 217 are closed.

[0055] Among them, for pipe diameters of DN50 and below, the first valve 210, the second valve 211, the third valve 212, the fourth valve 213, the fifth valve 214, the sixth valve 215, the seventh valve 216 and the eighth valve 217 can use electromagnetic valves as on-off valves. For pipe diameters above DN50, the first valve 210, the second valve 211, the third valve 212, the fourth valve 213, the fifth valve 214, the sixth valve 215, the seventh valve 216 and the eighth valve 217 can select on-off butterfly valves / on-off ball valves, and are controlled by time. After the time is up, the switch is automatic, and this switching interval time can be adjusted. The site can determine the appropriate time according to the pressure difference curve at the inlet and outlet of the heat exchanger.

[0056] For the pre-heater, after switching, the original cold-side medium enters the hot side (that is, the original cold fluid flowing through the second channel is converted to the cold fluid flowing through the first channel), and the salt scale precipitated in the heat exchanger can be dissolved, extending the cleaning cycle.

[0057] For the mirabilite pre-cooler, after switching, the original hot-side feed enters the cold side (that is, the original hot fluid flowing through the second channel is converted to the hot fluid flowing through the first channel), and the mirabilite precipitated from the original cold fluid can be dissolved, extending the cleaning cycle.

[0058] Although the present utility model has been illustrated and described with reference to some preferred embodiments thereof, those of ordinary skill in the art should understand that the above content is a further detailed description of the present utility model in connection with specific embodiments, and it cannot be determined that the specific implementation of the present utility model is limited only to these descriptions. Those skilled in the art can make various changes in form and detail, including making several simple deductions or substitutions, without departing from the spirit and scope of the present utility model.

Claims

1. A precooling heat exchange system, characterized in that, Comprising: A heat exchanger, the outer wall of the heat exchanger is provided with a first inlet, a first outlet, a second inlet and a second outlet, and the interior of the heat exchanger is provided with a first channel and a second channel. The first inlet and the first outlet are both in communication with the first channel, and the second inlet and the second outlet are both in communication with the second channel; A fluid conversion mechanism for switching the fluids in the first channel and the second channel, wherein, In the first state, the first channel is used for introducing a hot fluid, and the second channel is used for introducing a cold fluid; In the second state, the first channel is used for introducing a cold fluid, and the second channel is used for introducing a hot fluid.

2. The pre-cooling heat exchange system according to claim 1, wherein The heat exchanger is a plate heat exchanger.

3. The pre-cooling heat exchange system according to claim 1, wherein, The heat exchanger is a tubular heat exchanger.

4. The pre-cooling heat exchange system according to claim 2 or 3, characterized in that, The fluid conversion mechanism includes a plurality of pipes, and the plurality of pipes include a first pipe, a second pipe, a third pipe, a fourth pipe, a fifth pipe, a sixth pipe, a seventh pipe and an eighth pipe. Among them, the first pipe and the second pipe are connected in parallel and are in communication with the first inlet, the third pipe and the fourth pipe are connected in parallel and are in communication with the second inlet, the fifth pipe and the sixth pipe are connected in parallel and are in communication with the first outlet, and the seventh pipe and the eighth pipe are connected in parallel and are in communication with the second outlet; wherein, In the first state, the hot fluid flows through the first pipe, the first channel, and the fifth pipe respectively, and the cold fluid flows through the fourth pipe, the second channel, and the eighth pipe respectively; In the second state, the hot fluid flows through the third pipe, the second channel, and the seventh pipe respectively; the cold fluid flows through the second pipe, the first channel, and the sixth pipe respectively.

5. The pre-cooling heat exchange system according to claim 4, wherein The fluid conversion mechanism further includes a plurality of valves, and the valves include a first valve, a second valve, a third valve, a fourth valve, a fifth valve, a sixth valve, a seventh valve and an eighth valve. The first valve is arranged on the first pipe, the second valve is arranged on the second pipe, the third valve is arranged on the third pipe, the fourth valve is arranged on the fourth pipe, the fifth valve is arranged on the fifth pipe, the sixth valve is arranged on the sixth pipe, the seventh valve is arranged on the seventh pipe, and the eighth valve is arranged on the eighth pipe.

6. The pre-cooling heat exchange system according to claim 5, wherein, The first valve, the second valve, the third valve, the fourth valve, the fifth valve, the sixth valve, the seventh valve and the eighth valve are all solenoid valves.

7. The pre-cooling heat exchange system according to claim 1, wherein, A sewage discharge point is further provided on the heat exchanger. Axially, the sewage discharge point is arranged at the bottom end of the heat exchanger.

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