Steam U-shaped pipe internal reflux condensation cryogenic gas heater and method thereof
By using an inverted U-tube internal reflux condensation cryogenic gas heater, and utilizing the design of an inverted U-tube and a liquid seal balance plate, the problem of poor condensate flow in cryogenic medium heat exchangers is solved, achieving equipment miniaturization and cost reduction, and providing good temperature stress relief effect.
Patent Information
- Application Number
- CN202511114449.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-11
- Publication Date
- 2025-11-04
AI Technical Summary
In the process of cryogenic heat exchange, existing heat exchangers are prone to solidification due to poor condensate flow, which can cause equipment failure. Moreover, existing equipment is expensive, bulky, and difficult to effectively cope with temperature stress.
The inverted U-shaped tube internal reflux condensation cryogenic gas heater utilizes the inverted U-shaped tube structure and liquid seal balance plate design to ensure timely reflux of condensate and continuous heat exchange with steam, preventing condensate from solidifying due to excessively low temperature. At the same time, 304 stainless steel is used to reduce costs.
It effectively prevents condensate from solidifying, reduces equipment temperature stress, cuts equipment costs in half, has good temperature stress relief capabilities, and features a simple structure and effective control.
Smart Images
Figure CN120890281A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of heat exchangers, and particularly relates to a steam U-shaped tube internal reflux condensation deep cooling gas heater structure and a blowing process method for non-condensed steam in steam. BACKGROUND
[0002] Deep cooling generally refers to a temperature range of 233K-77K. In the heat exchange process of low-temperature gas and steam in the temperature range, when the steam condensate flows poorly, the condensate in the tube is easily solidified to cause heat exchanger failure due to too low temperature.
[0003] When a tube-in-shell heat exchanger is used for cooling, the deep cooling medium usually adopts ethylene glycol aqueous solution and other heat streams with low solidification points; the deep cooling medium can also achieve the purpose of reheat by using an air-cooled vaporizer, but the air-cooled vaporizer is usually too large in size and needs one to be used and one to be reserved for regular defrosting; when the deep cooling medium uses a water bath type vaporizer for heating, natural circulation or forced convection circulation of shell side circulating water is usually used, and steam is introduced to maintain the water temperature generally not lower than 60 DEG C. At this time, the shell side spacing is large, and it is not easy to cause heat exchanger damage when solidification occurs. At this time, the heat exchanger is heavy in weight and high in cost.
[0004] Therefore, it is urgent to provide a new heat exchanger to effectively protect the condensate flow and better cope with the temperature stress elimination of the deep cooling medium in the reheat process. SUMMARY
[0005] The application aims to overcome the defects in the prior art and provide a steam U-shaped tube internal reflux condensation deep cooling gas heater and a method thereof. The application adopts an inverted reflux condensation heat exchanger to effectively protect the condensate flow, and adopts a U-shaped tube structure to better cope with the temperature stress elimination of the deep cooling medium in the reheat process.
[0006] The specific technical scheme adopted by the application is as follows:
[0007] In a first aspect, the application provides a steam U-shaped tube internal reflux condensation deep cooling gas heater, which comprises an inverted U-shaped tube heat exchanger, a condensate liquid level regulating valve, a steam inlet on-off valve and a steam venting on-off valve.
[0008] The inverted U-shaped tube heat exchanger comprises an upper heat exchanger shell and a lower tube box, and the heat exchanger shell and the tube box are not communicated with each other; a downwardly open U-shaped tube bundle body is arranged in the heat exchanger shell, and a torch gas passage is formed between the outer wall of the U-shaped tube bundle body and the inner wall of the heat exchanger shell; a torch gas inlet is formed on one side of the heat exchanger shell, a torch gas outlet is formed on the other side of the heat exchanger shell, and an air outlet is formed on the top of the heat exchanger shell; the bottom opening of the U-shaped tube bundle body extends into the tube box, is communicated with the inner cavity of the tube box, and forms a low-pressure steam passage; the low-pressure steam passage and the torch gas passage are not communicated with each other and can realize heat exchange through the U-shaped tube bundle body; the upper part of the inner cavity of the tube box is divided into a left upper cavity and a right upper cavity which are not communicated with each other by a vertical liquid seal balance plate, and the bottom of the liquid seal balance plate is below the liquid level; a first steam inlet communicated with the left upper cavity and a second steam inlet communicated with the right upper cavity are respectively formed on the two sides of the tube box, and a condensate outlet is formed on the bottom of the tube box; the first steam inlet and the second steam inlet are communicated with a total steam pipeline through a first steam pipeline and a second steam pipeline respectively, a steam inlet switch valve is arranged on the second steam pipeline, a steam branch is formed on the second steam pipeline downstream of the steam inlet switch valve, and a steam vent switch valve is arranged on the steam branch; the condensate outlet is communicated with the outside through a condensate pipeline provided with a condensate liquid level adjusting valve.
[0009] Preferably, the heat exchanger shell, the U-shaped tube bundle body and the tube box are coaxially arranged.
[0010] Preferably, the bottom of the heat exchanger shell and the top of the tube box are connected through flanges.
[0011] Preferably, the heat exchanger shell is an open and closed inverted U-shaped structure, and the tube box is an open and closed U-shaped structure.
[0012] Preferably, the heat exchanger shell, the U-shaped tube bundle body and the tube box are made of 304 stainless steel.
[0013] Preferably, the liquid seal balance plate is a vertically arranged plate body, the top of the plate body is connected with the top of the tube box, the two sides of the plate body are connected with the side walls of the tube box, and the bottom of the plate body is spaced apart from the bottom of the tube box.
[0014] Further, the liquid seal balance plate and the tube box are welded.
[0015] Preferably, a liquid level meter is arranged in the tube box; the liquid level meter is connected with the condensate liquid level adjusting valve through a signal line, and is used for feeding back and adjusting the opening degree of the condensate liquid level adjusting valve.
[0016] Preferably, a support is arranged outside the tube box.
[0017] In a second aspect, the application provides a heat exchange method using the steam U-shaped tube internal reflux condensation deep cold gas heater according to any one of the first aspect.
[0018] S1: In the heat exchange process, low-pressure steam and low-temperature flare gas are simultaneously introduced into the inverted U-shaped tube heat exchanger, as follows:
[0019] The steam inlet switch valve and the condensate level regulating valve are opened, and the steam vent switch valve is closed; low-pressure steam is introduced from the total steam pipeline and is divided into first and second streams of steam through the first and second steam pipelines, and the first and second streams of steam enter the low-pressure steam passage through the first and second steam inlets; due to the liquid seal effect of the liquid seal balance plate, the first and second streams of steam climb upward along the U-shaped tube bundle body and are condensed after heat exchange with the low-temperature flare gas in the flare gas passage, and then fall back into the liquid pool at the lower part of the tube box as condensate; in the backflow process, the first and second streams of steam are continuously introduced into the low-pressure steam passage to supplement the steam, so that the steam and the condensate are in contact and heat exchange at all times, preventing the condensate from solidifying due to excessively low temperature after heat exchange; finally, the condensate flows out from the condensate outlet and is throttled by the condensate level regulating valve to form the post-valve condensate for the boundary area;
[0020] The low-temperature flare gas enters the flare gas passage through the flare gas inlet and is discharged as normal-temperature flare gas for the boundary area through the flare gas outlet after heat exchange;
[0021] S2: During the heat exchange process, the inner wall of the U-shaped tube bundle body is periodically purged, as follows:
[0022] The steam inlet switch valve is closed, and the steam vent switch valve is opened; the first stream of steam enters the low-pressure steam passage through the first steam inlet and, under the liquid seal effect of the liquid seal balance plate, climbs upward along the U-shaped tube bundle body to purge the interior of the U-shaped tube bundle body; at this time, the residual non-condensable gas is discharged from the second steam inlet through the steam vent switch valve;
[0023] S3: After the heat exchange is completed, the residual gas in the flare gas passage is discharged through the air outlet.
[0024] Compared with the prior art, the device has the following beneficial effects:
[0025] In use, the steam condensate can be backflowed to the tube box in time, reducing the heat exchange time of the condensate with the low-temperature flare gas and preventing solidification. The steam condensate is supplemented with steam during the backflow process, so that the steam and the condensate are in contact and heat exchange at all times, preventing the condensate from solidifying due to excessively low temperature after heat exchange. The inverted U-shaped tube heat exchanger has good temperature stress relieving capacity, and the cost of the heat exchanger of the present application is about half of that of a conventional water bath type heat exchanger. The device has the outstanding characteristics of small equipment, low investment cost, simple and effective control, and solves the problem of insufficient condensate flow in the existing horizontal heat exchanger, which causes solidification and damage. BRIEF DESCRIPTION OF DRAWINGS
[0026] Figure 1A schematic diagram of the device of the present application;
[0027] Figure 2 A schematic diagram of the device of the present application; Figure 1 A schematic diagram of the device of the present application;
[0028] In the drawing, the reference numerals are: 1, inverted U-tube heat exchanger, 2, condensate level regulating valve, 3, steam inlet on-off valve, 4, steam vent on-off valve, 5, heat exchanger shell, 6, U-tube bundle body, 7, flange, 8, tube sheet, 9, liquid seal balance plate, 10, support; A, low-pressure steam, B, first route steam, C, second route steam, D, non-condensable gas, E, condensate after valve, F, low-temperature flare gas, G, normal-temperature flare gas, H, residual gas, I, condensate. DETAILED DESCRIPTION
[0029] In order to make the above objectives, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the drawings. In the following description, a large number of specific details are set forth in order to facilitate a thorough understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the spirit of the present application, so the present application is not limited to the specific embodiments disclosed below. The technical features in each embodiment of the present application can be combined accordingly without conflict.
[0030] In the description of the present application, it should be understood that when an element is considered to be "connected" to another element, it can be directly connected to the other element or indirectly connected to the other element with an intermediate element. In contrast, when an element is referred to as being "directly" connected to another element, there is no intermediate element.
[0031] In the description of the present application, it should be understood that the terms "first", "second" are only used for distinguishing description purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features.
[0032] In the description of the present application, it should be understood that the expressions "low pressure", "low temperature" and "normal temperature" in the media "low pressure steam", "low temperature flare gas", "normal temperature flare gas" and the like are only used for distinguishing description purposes and are relative "low pressure", "low temperature" and "normal temperature", and cannot be understood as indicating or implying relative importance or implicitly indicating the temperature or pressure limit of the technical features indicated.
[0033] As Figure 1As shown, this invention provides a steam U-tube in-circuit condensation cryogenic gas heater. The heater mainly includes an inverted U-tube heat exchanger 1, a condensate level regulating valve 2, a steam inlet switch valve 3, and a steam vent switch valve 4. This invention utilizes the falling film condensation flow characteristics of steam within the tube and the temperature stress compensation characteristics of the U-tube, enabling the inverted U-tube heat exchanger to exhibit good adaptability in terms of condensate flow and temperature stress.
[0034] The structure and connection methods of each component will be explained in detail below.
[0035] In the device of the present invention, such as Figure 2 As shown, the inverted U-tube heat exchanger 1 mainly includes a heat exchanger shell 5, a tube box 8, a U-tube bundle 6, and a liquid seal balance plate 9. The heat exchanger shell 5 and the tube box 8 are both relatively sealed structures, with the heat exchanger shell 5 located above and the tube box 8 located below, and the heat exchanger shell 5 and the tube box 8 are not connected to each other.
[0036] In a preferred embodiment of the present invention, the bottom of the heat exchanger shell 5 and the top of the tube box 8 are connected by a flange 7, but other detachable connection methods can also be selected according to actual needs. The heat exchanger shell 5 can be an inverted U-shaped structure with the opening closed by a partition, and the tube box 8 can be a U-shaped structure with the opening closed by a partition, and the two are arranged coaxially at the top and bottom.
[0037] In the device of the present invention, a U-shaped tube bundle 6 with a downward opening is provided inside the heat exchanger shell 5. The U-shaped tube bundle 6 adopts a vertical inverted buckle structure, which is an inverted U-shaped tube. This arrangement can ensure that the condensate can flow back to the liquid pool in time and avoid prolonged heat exchange and solidification with the cryogenic medium.
[0038] Specifically, the principle of the inverted U-tube heat exchanger used in this invention is as follows:
[0039] Shell and tube heat exchanger is a common heat exchanger in the market, simple structure, low cost, mature technology, with universality and versatility. When steam is used to heat cryogenic gas, U-tube heat exchanger can be usually selected due to large temperature difference. U-tube heat exchanger is a kind of heat exchanger with good temperature stress applicability in shell and tube heat exchanger, and is commonly used in occasions with large temperature difference between cold and hot streams. The conventional cryogenic gas steam heater usually adopts a horizontally placed U-tube heater. When the pressure of the cryogenic gas is low, the cryogenic gas is usually heated in the shell side, and the steam is condensed in the tube side. During this process, when the steam becomes condensed liquid, the volume shrinks sharply, and the flow of the condensed liquid is usually gravity-controlled flow, that is, the steam flows in the horizontal tube by itself, and the flow rate is low. At this time, the heat exchanger may fail due to the flow problem of the condensed liquid. For example, the U-tube torch heater of the cryogenic device usually has the failure of freezing and cracking of the heat exchange tube. Therefore, the present application adopts an inverted U-tube heat exchanger, which is arranged in the form of an inverted U-tube, and has the characteristics of condensed liquid falling film flow at the same time when the temperature stress is adapted. In use, the steam is fully condensed and flows back in the inverted U-tube heat exchanger, and drops from the tube opening into the tube tank pool. The liquid seal balance plate has a considerable height and is used for blowing off the non-condensable gas in the steam. The liquid seal balance plate is connected at the tube tank head. The tube side is a U-tube heat exchanger structure shared by one-pass and two-pass.
[0040] In the device of the present application, there is a certain interval between the inner wall of the heat exchanger shell 5 and the U-tube bundle body 6, so that the interval between the outer wall of the U-tube bundle body 6 and the inner wall of the heat exchanger shell 5 constitutes a torch gas passage. One side of the heat exchanger shell 5 is provided with a torch gas inlet for introducing low-temperature torch gas F, and the other side of the heat exchanger shell 5 is provided with a torch gas outlet for discharging normal-temperature torch gas G after heat exchange; the top of the heat exchanger shell 5 is provided with an air exhaust outlet. The torch gas inlet, the torch gas outlet and the air exhaust outlet are all connected with pipelines, and can be controlled to open and close.
[0041] In the device of the present application, the bottom opening of the U-tube bundle body 6 extends into the tube tank 8 from the top, and is in communication with the inner cavity of the tube tank 8, and the inner cavities in communication constitute a low-pressure steam passage. The low-pressure steam passage and the torch gas passage are not in communication with each other, but can realize heat exchange through the U-tube bundle body 6.
[0042] As a preferred embodiment of the present application, the heat exchanger shell 5, the U-tube bundle body 6 and the tube tank 8 can be coaxially arranged. In order to better the heat transfer effect, the materials of the heat exchanger shell 5, the U-tube bundle body 6 and the tube tank 8 can all be 304 stainless steel.
[0043] As a preferred embodiment of the present application, the tube tank 8 should have a certain height and have the function of storing liquid, and the tube tank 8 is provided with a support 10. The support 10 is used to keep the inverted U-tube heat exchanger 1 standing upright, and its structure can be adjusted according to the actual situation.
[0044] In the device of the present application, the upper part of the inner cavity of the tube box 8 is divided into left upper cavity and right upper cavity which are not communicated with each other by the vertical liquid seal balance plate 9, and the bottom of the liquid seal balance plate 9 is below the liquid level. That is to say, the upper part of the inner cavity of the tube box 8 is a cavity, and the lower part is a liquid pool.
[0045] As a preferred embodiment of the present application, the liquid seal balance plate 9 is a vertically arranged plate body, the top of which is connected with the top of the tube box 8, and the two sides of which are connected with the side walls of the tube box 8. There is a gap between the bottom of the liquid seal balance plate 9 and the bottom of the tube box 8, which is not welded and sealed with the tube box head, and is a communication structure, which can maintain the balance of the liquid level at both ends; at the same time, the liquid seal balance plate with a certain height has a liquid seal effect in the non-condensing displacement process.
[0046] In actual use, the connection mode between the liquid seal balance plate 9 and the tube box 8 can adopt welding connection.
[0047] In the device of the present application, the first steam inlet and the second steam inlet are respectively arranged on the two sides of the tube box 8, wherein the first steam inlet is communicated with the left upper cavity, and the second steam inlet is communicated with the right upper cavity. The first steam inlet is communicated with the total steam pipeline through the first steam pipeline, and the second steam inlet is communicated with the total steam pipeline through the second steam pipeline. That is to say, the total steam pipeline is divided into two parallel pipelines, i.e. the first steam pipeline and the second steam pipeline. The steam inlet on-off valve 3 is arranged on the second steam pipeline, the steam branch is arranged on the second steam pipeline downstream of the steam inlet on-off valve 3, and the steam vent on-off valve 4 is arranged on the steam branch. The condensate outlet is arranged at the bottom of the tube box 8, the condensate outlet is communicated with the outside through the condensate pipeline, and the condensate liquid level regulating valve 2 is arranged on the condensate pipeline.
[0048] As a preferred embodiment of the present application, the liquid level meter is arranged in the tube box 8. The liquid level meter is connected with the condensate liquid level regulating valve 2 through the signal line, and the liquid level signal is fed back to the condensate liquid level regulating valve 2 in real time, so that the condensate liquid level regulating valve 2 can adjust the opening degree according to the liquid level, and ensure that the liquid level in the tube box 8 can meet the set requirements.
[0049] Based on the above-mentioned steam U-shaped tube inner reflux condensation deep cooling gas heater, the present application further provides a heat exchange method, which is as follows:
[0050] S1: In the heat exchange process, the low-pressure steam A and the low-temperature flare gas F are simultaneously introduced into the inverted U-shaped tube heat exchanger 1, which is as follows:
[0051] Open the steam inlet switch valve 3 and the condensate level regulating valve 2, and close the steam vent switch valve 4. The low-pressure steam A is introduced from the total steam pipeline, and is divided into the first steam B and the second steam C through the first steam pipeline and the second steam pipeline, and the first steam B and the second steam C enter the low-pressure steam passage through the first steam inlet and the second steam inlet respectively. Due to the liquid seal effect of the liquid seal balance plate 9, the first steam B and the second steam C climb upward along the U-shaped tube bundle body 6, and are condensed after heat exchange with the low-temperature flare gas F in the flare gas passage, and then fall into the liquid pool at the lower part of the pipe box 8 in the form of condensate I. During the reflux process of the condensate I, the first steam B and the second steam C are continuously introduced into the low-pressure steam passage for replenishment, so that the steam is in contact with the condensate I for heat exchange at all times, and the temperature of the condensate I after heat exchange is prevented from being too low to solidify. Finally, the condensate I flows out from the condensate outlet, and after throttling through the condensate level regulating valve 2, the valve rear condensate E goes to the boundary area.
[0052] The low-temperature flare gas F enters the flare gas passage through the flare gas inlet, and after heat exchange, the flare gas G at normal temperature goes to the boundary area through the flare gas outlet.
[0053] S2: During the heat exchange process, the inner wall of the U-shaped tube bundle body 6 is periodically purged, specifically as follows:
[0054] Close the steam inlet switch valve 3, and open the steam vent switch valve 4. The first steam B enters the low-pressure steam passage through the first steam inlet, and under the liquid seal effect of the liquid seal balance plate 9, the first steam B climbs upward along the U-shaped tube bundle body 6 to purge the inside of the U-shaped tube bundle body 6, and at this time, the residual non-condensable gas D is discharged from the second steam inlet through the steam vent switch valve 4.
[0055] S3: After the heat exchange is completed, the residual gas H in the flare gas passage is discharged through the air outlet.
[0056] The above-described embodiments are only a preferred scheme of the present application, and are not intended to limit the present application. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present application. Therefore, any technical scheme obtained by equivalent replacement or equivalent transformation falls within the protection scope of the present application.
Claims
1. A steam U-shaped tube internal reflux condensation cryogenic gas heater, characterized in that, It includes an inverted U-tube heat exchanger (1), a condensate level regulating valve (2), a steam inlet switch valve (3), and a steam vent switch valve (4); The inverted U-tube heat exchanger (1) includes a heat exchanger shell (5) located at the top and a tube box (8) located at the bottom. The heat exchanger shell (5) and the tube box (8) are not connected to each other. A U-shaped tube bundle (6) with a downward opening is provided inside the heat exchanger shell (5). The outer wall of the U-shaped tube bundle (6) and the inner wall of the heat exchanger shell (5) form a flare gas channel. A flare gas inlet is opened on one side of the heat exchanger shell (5), a flare gas outlet is opened on the other side, and an exhaust air outlet is opened at the top. The bottom opening of the U-shaped tube bundle (6) extends into the tube box (8), communicates with the inner cavity of the tube box (8), and forms a low-pressure steam channel. The low-pressure steam channel and the flare gas channel are not connected to each other and can exchange heat through the U-shaped tube bundle (6). The tube box (8) The upper part of the inner cavity is divided into an upper left cavity and an upper right cavity that are not connected by a vertical liquid seal balance plate (9). The bottom of the liquid seal balance plate (9) is below the liquid surface. The pipe box (8) is provided with a first steam inlet connected to the upper left cavity and a second steam inlet connected to the upper right cavity on both sides respectively. A condensate outlet is provided at the bottom. The first steam inlet and the second steam inlet are connected to the main steam pipeline through the first steam pipeline and the second steam pipeline respectively. A steam inlet switch valve (3) is provided on the second steam pipeline. A steam branch is provided on the second steam pipeline downstream of the steam inlet switch valve (3). A steam vent switch valve (4) is provided on the steam branch. The condensate outlet is connected to the outside through a condensate pipeline with a condensate level regulating valve (2).
2. The steam U-tube internal reflux condensation cryogenic gas heater according to claim 1, characterized in that, The heat exchanger shell (5), U-shaped tube bundle (6) and tube box (8) are coaxially arranged.
3. A steam U-tube internal reflux condensation cryogenic gas heater according to claim 1, characterized in that, The bottom of the heat exchanger shell (5) and the top of the tube box (8) are connected by a flange (7).
4. A steam U-tube internal reflux condensation cryogenic gas heater according to claim 1, characterized in that, The heat exchanger shell (5) is an inverted U-shaped structure with an open and closed opening, and the tube box (8) is a U-shaped structure with an open and closed opening.
5. A steam U-tube internal reflux condensation cryogenic gas heater according to claim 1, characterized in that, The heat exchanger shell (5), U-shaped tube bundle (6) and tube box (8) are all made of 304 stainless steel.
6. A steam U-tube internal reflux condensation cryogenic gas heater according to claim 1, characterized in that, The liquid seal balance plate (9) is a vertically arranged plate. Its top is connected to the top of the tube box (8), its two sides are connected to the side walls of the tube box (8), and its bottom is spaced from the bottom of the tube box (8).
7. A steam U-tube internal reflux condensation cryogenic gas heater according to claim 6, characterized in that, The liquid seal balance plate (9) is welded to the pipe box (8).
8. A steam U-tube internal reflux condensation cryogenic gas heater according to claim 1, characterized in that, The pipe box (8) is equipped with a level gauge; the level gauge is connected to the condensate level regulating valve (2) via a signal line and is used to provide feedback to regulate the opening of the condensate level regulating valve (2).
9. A steam U-tube internal reflux condensation cryogenic gas heater according to claim 1, characterized in that, The pipe box (8) is provided with a support member (10) on its exterior.
10. A heat exchange method using a steam U-tube internal reflux condensation cryogenic gas heater according to any one of claims 1 to 9, characterized in that, Specifically as follows: S1: During the heat exchange process, low-pressure steam (A) and low-temperature flare gas (F) are simultaneously introduced into the inverted U-tube heat exchanger (1), as detailed below: Open the steam inlet switch valve (3) and the condensate level regulating valve (2), and close the steam vent switch valve (4); low-pressure steam (A) enters from the main steam pipeline, and is divided into the first steam (B) and the second steam (C) through the first steam pipeline and the second steam pipeline. The first steam (B) and the second steam (C) enter the low-pressure steam channel through the first steam inlet and the second steam inlet, respectively; due to the liquid seal effect of the liquid seal balance plate (9), the first steam (B) and the second steam (C) flow along the U-shaped tube bundle (6) The liquid rises upwards, exchanges heat with the low-temperature flare gas (F) in the flare gas channel, and condenses. It then falls back into the liquid pool at the bottom of the tube box (8) as condensate (I). During the reflux process, the first steam (B) and the second steam (C) are continuously introduced into the low-pressure steam channel to replenish the condensate, ensuring that the steam and condensate (I) are in contact and exchange heat at all times, and preventing the condensate (I) from solidifying due to excessively low temperature after heat exchange. Finally, the condensate (I) flows out from the condensate outlet, and after being throttled by the condensate level regulating valve (2), it is discharged into the boundary area as condensate (E) after the valve. Low-temperature flare gas (F) enters the flare gas channel through the flare gas inlet, and after heat exchange, it exits the boundary area as ambient temperature flare gas (G) through the flare gas outlet. S2: During the heat exchange process, the inner wall of the U-shaped tube bundle (6) is periodically purged, as follows: Close the steam inlet switch valve (3) and open the steam vent switch valve (4); the first steam (B) enters the low-pressure steam channel through the first steam inlet. Under the liquid seal action of the liquid seal balance plate (9), the first steam (B) rises along the U-shaped tube bundle (6) and purges the inside of the U-shaped tube bundle (6). At this time, the remaining non-condensable gas (D) is discharged from the second steam inlet through the steam vent switch valve (4); S3: After the heat exchange is completed, the residual gas (H) in the flare gas passage is discharged through the air exhaust outlet.