Condensate self-flowing type low-temperature gas U-shaped pipe heater and condensate leading-out method thereof

Abstract

The invention discloses a condensate self-flowing type low-temperature gas U-shaped pipe heater and a condensate leading-out method thereof, and belongs to the field of cryogenic equipment. The device comprises a liquid collection expanding pipe and a horizontal U-shaped pipe heat exchanger, the horizontal U-shaped tube heat exchanger comprises a tube box and a heat exchanger shell, a U-shaped heat exchange tube bundle is arranged in the heat exchanger shell, and openings in the two ends of the heat exchange tube bundle extend into the tube box. An inner cavity of the tube box is divided into an upper cavity and a lower cavity which are not communicated through a condensate collecting pass partition plate, and openings in the two ends of the heat exchange tube bundle are located in the upper cavity and the lower cavity respectively. The condensate collection pass partition plate is transversely arranged, the middle of the condensate collection pass partition plate is sunken downwards to be used for converging condensate, and a first-pass condensate outlet is formed in the sunken position. The pass partition plate of the tube box is different from a conventional structure, a sunken pass partition plate structure is adopted, and a condensate evacuation opening is formed in the lower sinking position of the partition plate and used for timely leading out condensate to avoid the situation that a lower row tube bundle of the first pass of the tube box is submerged by the condensate, and consequently no steam flows into a heat exchange tube.

Description

Technical Field

[0001] The invention belongs to the field of cryogenic equipment, and in particular relates to a condensate self-flowing low-temperature gas U-tube heater using saturated steam as a heat source and a process method for respectively leading out condensate in each process. Background Art

[0002] Cryogenics generally refers to the temperature range of 233K-77K. In this range, during the heat exchange process between the cryogenic gas and the steam heat exchanger, due to the low temperature, when the steam condensate does not flow smoothly, it is easy to cause the condensate in the tube to solidify and cause the heat exchanger to malfunction.

[0003] Usually, when a shell and tube heat exchanger is used to heat a cryogenic medium, a heat stream with a low solidification point such as ethylene glycol aqueous solution is used; the cryogenic medium can also be reheated by using an air-temperature vaporizer, but the air-temperature vaporizer is usually too large and requires regular defrosting. When a water bath vaporizer is used to heat a cryogenic medium, the shell-side circulating water is usually circulated naturally or by forced convection, and steam is introduced to maintain the water temperature generally not lower than 60°C. At this time, the shell-side spacing is large, and it is not easy to cause damage to the heat exchanger during solidification. However, this heat exchanger is heavy and expensive.

[0004] The horizontal U-tube structure can better deal with the elimination of equipment temperature stress during the rewarming process of cryogenic media. When the steam condenses in the tube, due to the rapid contraction of the volume, a forced convection environment is usually not formed. When the low-temperature gas pressure on the shell side is low, it is usually necessary to increase the number of heat exchange tubes to avoid vibration damage to the heat exchange tubes caused by the shell-side gas. At this time, the flow rate on the tube side is further reduced. This causes part of the condensed liquid in the first-pass tube bundle to flow back to the inlet tube box, causing the lower row of tube bundles in the first-pass tube box to be submerged, resulting in no steam flowing into the lower row of tube bundles, resulting in the saturated liquid being cooled to below the freezing point by the low-temperature gas during the heat exchange process, and the volume expands, causing the heat exchange tubes to burst.

[0005] Therefore, it is urgent to provide a new U-tube heater structure that can effectively evacuate condensate without condensate blockage and ensure that the lower tube bundle of the first-pass tube box has sufficient steam replenishment. Summary of the invention

[0006] The purpose of the present invention is to overcome the defects in the prior art and provide a condensate self-flowing low-temperature gas U-tube heater and a condensate extraction method thereof without making major changes to the overall equipment. The device is designed with a condensate collection and extraction structure at the steam inlet, which is used for evacuating the condensate from the first-pass tube bundle of the U-tube heat exchanger to the steam inlet tube box. The cost of modifying the device of the present invention is extremely low and can be almost ignored; the structure is simple, the processing and manufacturing are simple, there is no complicated processing process, and it has high economic efficiency.

[0007] The specific technical solutions adopted by the present invention are as follows:

[0008] In a first aspect, the present invention provides a condensate self-flowing low-temperature gas U-tube heater, comprising a liquid collecting expansion tube and a horizontal U-tube heat exchanger;

[0009] The horizontal U-tube heat exchanger comprises a tube box located on the left and a heat exchanger shell located on the right, the tube box and the heat exchanger shell are not connected to each other; a U-shaped heat exchange tube bundle with an opening facing left is arranged in the heat exchanger shell, and a low-temperature gas channel is formed between the outer wall of the heat exchange tube bundle and the inner wall of the heat exchanger shell; the lower side wall of the heat exchanger shell is connected to the shell-side inlet pipeline, and the upper side wall is connected to the shell-side outlet pipeline; the openings at both ends of the heat exchange tube bundle extend into the tube box, are connected to the inner cavity of the tube box and form a steam channel; the low-temperature gas channel and the steam channel are not connected to each other and heat exchange can be achieved through the heat exchange tube bundle; the inner cavity of the tube box is divided into upper and lower parts that are not connected to each other by a condensate collection partition plate The heat exchange tube bundle has two openings at both ends located in the upper chamber and the lower chamber respectively; the condensate collecting partition is arranged horizontally and is recessed in the middle to collect condensate, a first-pass condensate outlet is provided at the recess and is connected to the air cavity of the liquid collecting expansion tube through the first condensate output pipeline; a second-pass condensate outlet is provided at the bottom of the lower chamber and is connected to the air cavity of the liquid collecting expansion tube through the second condensate output pipeline; a steam inlet is provided at the top of the upper chamber and is connected to the steam inlet pipeline, and the air cavity of the liquid collecting expansion tube is connected to the steam inlet through a pipeline; the bottom of the liquid pool of the liquid collecting expansion tube is connected to the third condensate output pipeline provided with a condensate regulating valve.

[0010] Preferably, the tube box, heat exchange tube bundle and heat exchanger shell are coaxially arranged.

[0011] Preferably, the condensate collection partition is arranged in the middle of the inner cavity of the tube box, and a square groove is formed in the middle.

[0012] Preferably, the horizontal U-tube heat exchanger is tilted to the left as a whole to facilitate condensate collection.

[0013] Preferably, the tube box and the heat exchanger shell are connected via a flange.

[0014] Preferably, the liquid collecting expansion tube is a vertically arranged tube structure, with an air cavity at the top and a liquid pool at the bottom.

[0015] Preferably, a liquid level gauge is provided in the liquid collecting expansion tube; the liquid level gauge is connected to the condensate regulating valve via a signal line, and is used to adjust the valve opening according to the liquid level feedback of the liquid pool.

[0016] Preferably, the tube box and the heat exchanger shell are both U-shaped structures with closed openings.

[0017] In a second aspect, the present invention provides a condensate extraction method using the condensate self-flowing low-temperature gas U-tube heater according to any one of the first aspects, which is specifically as follows:

[0018] During the heat exchange process, low-temperature gas and saturated steam are simultaneously introduced into the horizontal U-tube heat exchanger, as follows:

[0019] Saturated steam enters the upper chamber of the tube box through the steam inlet from the steam inlet pipe, and then enters the inner cavity of the heat exchange tube bundle; at the same time, the low-temperature gas enters the heat exchanger shell through the shell inlet pipe; saturated steam and low-temperature gas exchange heat at the heat exchange tube bundle, and the saturated steam in the heat exchange tube bundle is condensed by heat exchange; part of the condensate in the first-pass tube bundle of the heat exchange tube bundle flows back and gathers to the sunken depression of the condensate collection partition, and the condensate is evacuated to the liquid collection expansion tube through the first condensate outlet located at the lowest end of the sunken place through the first condensate output pipeline; the condensate in the second-pass tube bundle of the heat exchange tube bundle is evacuated to the liquid collection expansion tube through the second condensate output pipeline through the second condensate outlet located at the lowest point of the tube box;

[0020] During this process, the condensate regulating valve located at the lower end of the liquid collecting expansion tube controls the valve opening according to the liquid level height of the liquid pool in the liquid collecting expansion tube to adjust the liquid level in the liquid collecting expansion tube to maintain it at a set value, thereby preventing saturated steam from penetrating into the third condensate output pipeline.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention adopts a condensate collection and evacuation structure on the upper part of the first-pass pipe box partition. The pipe box partition is different from the conventional structure. It adopts a sinking partition structure. A condensate evacuation port is set at the low position of the partition to timely lead out the condensate to avoid the first-pass lower tube bundle of the pipe box being submerged by condensate, resulting in no steam flowing into the heat exchange tube. The U-tube heat exchanger structure that leads the condensate of each pass separately can effectively evacuate the condensate without condensate blockage, ensuring that the first-pass lower tube bundle has sufficient steam to supplement. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of the device of the present invention;

[0024] Figure 2 for Figure 1 Schematic diagram of the structure of a medium horizontal U-tube heat exchanger;

[0025] The reference numerals in the figure are: steam inlet pipeline 1, first condensate output pipeline 2, second condensate output pipeline 3, liquid collecting expansion pipe 4, condensate regulating valve 5, third condensate output pipeline 6, shell side inlet pipeline 7, shell side outlet pipeline 8, horizontal U-tube heat exchanger 9, tube box 10, heat exchange tube bundle 11, heat exchanger shell 12, steam inlet 13, first-pass condensate outlet 14, second-pass condensate outlet 15, condensate collection partition plate 16. DETAILED DESCRIPTION

[0026] In order to make the above-mentioned purpose, features and advantages of the present invention more obvious and easy to understand, the specific implementation mode of the present invention is described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below. The technical features in each embodiment of the present invention can be combined accordingly without conflicting with each other.

[0027] In the description of the present invention, it is to be understood that when an element is considered to be "connected" to another element, it may be directly connected to the other element or indirectly connected, that is, there are intermediate elements. On the contrary, when an element is said to be "directly" connected to another element, there are no intermediate elements.

[0028] In the description of the present invention, it should be understood that the terms "first", "second", and "third" are only used for distinguishing description purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second", and "third" may explicitly or implicitly include at least one of the features.

[0029] In the description of the present invention, it is necessary to understand that the expression "low temperature" in the medium "low temperature gas" is only used for distinguishing description purposes and is a "low temperature" in a relative situation, and cannot be understood as indicating or implying relative importance or implicitly indicating the temperature limit of the indicated technical features.

[0030] like Figure 1 As shown, a condensate self-flowing low-temperature gas U-tube heater provided by the present invention is improved based on the following principles:

[0031] Shell and tube heat exchangers are common heat exchangers on the market, with simple structure, low cost, mature process technology, and universality. When using steam to heat cryogenic gas, due to the large temperature difference, a U-tube heat exchanger can usually be selected. The U-tube heat exchanger is a heat exchanger with good temperature stress applicability among shell and tube heat exchangers, and is commonly used in occasions where the temperature difference between cold and hot streams is large. When steam is usually used to heat cryogenic gas, when the steam condenses in the tube, due to the rapid volume contraction, a forced convection environment cannot usually be formed. When the shell-side low-temperature gas pressure is low, it is usually necessary to increase the number of heat exchange tubes to avoid vibration damage to the heat exchange tubes caused by the shell-side gas. At this time, the tube side flow rate is further reduced. As a result, part of the condensed liquid in the first-pass tube bundle flows back to the inlet tube box, causing the lower row of tube bundles in the first-pass tube box to be submerged, resulting in no steam flowing into the lower row of tube bundles, resulting in the saturated liquid being cooled to below the freezing point by the low-temperature gas during the heat exchange process, and the volume expands, causing the heat exchange tube to burst. Therefore, the present invention adopts a condensate collection and evacuation structure on the upper part of the first-pass tube box partition. The pipe box partition is different from the conventional structure. It adopts a sunken partition structure. A condensate evacuation port is set at the low position of the partition to lead out the condensate in time to avoid the lower tube bundle of the first pass of the pipe box being submerged by condensate, resulting in no steam flowing into the heat exchange tube.

[0032] The heater of the present invention mainly includes a steam inlet pipeline 1, a first condensate output pipeline 2, a second condensate output pipeline 3, a liquid collecting expansion pipe 4, a condensate regulating valve 5, a third condensate output pipeline 6, a shell-side inlet pipeline 7, a shell-side outlet pipeline 8, a horizontal U-tube heat exchanger 9, a pipe box 10, a heat exchange tube bundle 11, a heat exchanger shell 12, a steam inlet 13, a first-pass condensate outlet 14, a second-pass condensate outlet 15, and a condensate collection partition plate 16.

[0033] The structure and connection method of each component will be described in detail below.

[0034] In the device of the present invention, Figure 2 As shown, the horizontal U-tube heat exchanger 9 mainly includes a tube box 10, a heat exchange tube bundle 11 and a heat exchanger shell 12. The tube box 10 is located on the left, the heat exchanger shell 12 is located on the right, and the tube box 10 and the heat exchanger shell 12 are not connected to each other.

[0035] As a preferred embodiment of the present invention, the pipe box 10 and the heat exchanger shell 12 are detachably connected, for example, they can be connected by a flange. The pipe box 10 and the heat exchanger shell 12 are both U-shaped structures with closed openings, the circular openings of the two are arranged opposite to each other, and the openings of the two are sealed by a plate.

[0036] In the device of the present invention, Figure 2As shown, a U-shaped heat exchange tube bundle 11 is arranged in the heat exchanger shell 12, and the U-shaped opening of the heat exchange tube bundle 11 faces left. A low-temperature gas channel is formed between the outer wall of the heat exchange tube bundle 11 and the inner wall of the heat exchanger shell 12, that is, when in use, low-temperature gas flows in the low-temperature gas channel. The lower end of the heat exchanger shell 12 is open and connected to the shell-side inlet pipe 7, and the upper end is open and connected to the shell-side outlet pipe 8. In actual use, low-temperature gas is introduced into the low-temperature gas channel through the shell-side inlet pipe 7, and the low-temperature gas after heat exchange flows out of the heat exchanger shell 12 from the shell-side outlet pipe 8.

[0037] In the device of the present invention, Figure 2 As shown, the heat exchange tube bundle 11 is a U-shaped structure, and its two end openings are both extended into the tube box 8, connected with the inner cavity of the tube box 8 and together form a steam channel. The low-temperature gas channel and the steam channel are not connected to each other. In actual use, the media in the two channels can achieve heat exchange through the heat exchange tube bundle 11.

[0038] As a preferred embodiment of the present invention, the tube box 10, the heat exchange tube bundle 11 and the heat exchanger shell 12 are coaxially arranged.

[0039] In the device of the present invention, Figure 2 As shown, the inner cavity of the tube box 10 is divided into an upper chamber and a lower chamber that are not connected to each other by a condensate collection partition 16, and the openings at both ends of the heat exchange tube bundle 11 are respectively located in the upper chamber and the lower chamber. The condensate collection partition 16 is arranged horizontally, and the middle part of the plate surface is concave downward. The concave arrangement facilitates the collection of condensate. A first-pass condensate outlet 14 is provided at the bottom of the concave part. The first-pass condensate outlet 14 is connected to the upper air cavity of the liquid collection expansion tube 4 through the first condensate output pipeline 2.

[0040] In actual use, external steam enters the upper chamber of the tube box 10 through the steam inlet pipe 1 , and then enters the lower chamber of the tube box 10 through the U-shaped channel of the heat exchange tube bundle 11 .

[0041] As a preferred embodiment of the present invention, the condensate collecting partition plate 16 can be arranged in the middle of the inner cavity of the tube box 10, and the middle of the plate surface is a square groove structure. Of course, the shape and size of the groove can be adjusted according to actual conditions, as long as the purpose of gathering the condensate in the first-pass tube bundle can be achieved.

[0042] In the device of the present invention, Figure 2As shown, a second-pass condensate outlet 15 is provided at the lowest position of the bottom of the lower chamber, and the second-pass condensate outlet 15 is connected to the air cavity of the liquid collecting expansion tube 4 through the second condensate output pipeline 3. A steam inlet 13 is provided at the top of the upper chamber, and the steam inlet 13 is connected to the steam inlet pipeline 1, and external steam can enter the inner cavity of the pipe box 10 through the steam inlet pipeline 1. The air cavity of the liquid collecting expansion tube 4 is connected to the steam inlet 13 through a pipeline to balance the air pressure, so that the pressure of the inner cavity of the pipe box 10 and the air cavity of the liquid collecting expansion tube 4 are the same.

[0043] In the device of the present invention, Figure 1 As shown, the bottom of the liquid pool of the liquid collecting expansion tube 4 is open and connected to the third condensate output pipeline 6, the third condensate output pipeline 6 is provided with a condensate regulating valve 5, and a liquid level gauge is provided in the liquid collecting expansion tube 4. The liquid level gauge is connected to the condensate regulating valve 5 through a signal line, and is used to adjust the valve opening according to the liquid level feedback of the liquid pool.

[0044] As a preferred embodiment of the present invention, the liquid collecting expansion tube 4 is a vertically arranged tube structure, the upper part of which is an air cavity and the lower part is a liquid pool.

[0045] As a preferred embodiment of the present invention, in order to better gather the condensate in the first pass tube bundle and the second pass tube bundle in the heat exchange tube bundle 11, the horizontal U-tube heat exchanger 9 can be tilted to the left as a whole, so that the openings at both ends of the heat exchange tube bundle 11 are located at the bottom to facilitate the collection of the condensate.

[0046] By using any of the above-mentioned condensate self-flowing low-temperature gas U-tube heaters, the present invention also provides a condensate extraction method, such as Figure 1 and 2 As shown. The process method mainly adopts a condensate collection sinking structure through the condensate collection partition 16 of the horizontal U-tube heat exchanger 9, and timely guides the condensate to the liquid collection expansion pipe 4 through the first condensate output pipeline 2, so as to avoid condensate backflow and blockage of the lower row of tube bundles in the first pass tube box, and ensure that all heat exchange tubes in the first pass tube box have sufficient steam replenishment. The steps of the process method are as follows:

[0047] During the heat exchange process, the external low-temperature gas and saturated steam are simultaneously introduced into the horizontal U-tube heat exchanger 9, as follows:

[0048] The external saturated steam enters the upper chamber of the tube box 10 through the steam inlet 13 from the steam inlet pipe 1, and then enters the inner cavity of the heat exchange tube bundle 11. At the same time, the low-temperature gas enters the heat exchanger shell 12 through the shell inlet pipe 7. The saturated steam and the low-temperature gas exchange heat at the heat exchange tube bundle 11, and the saturated steam in the heat exchange tube bundle 11 is heat exchanged and condensed. Part of the condensate in the first-pass tube bundle of the heat exchange tube bundle 11 flows back and collects in the sunken depression of the condensate collection partition 16, and the condensate is evacuated to the liquid collection expansion tube 4 through the first-pass condensate outlet 14 located at the lowest end of the sunken place through the first condensate output pipe 2. The condensate in the second-pass tube bundle of the heat exchange tube bundle 11 is evacuated to the liquid collection expansion tube 4 through the second condensate output pipe 3 through the second-pass condensate outlet 15 located at the lowest part of the tube box 10.

[0049] During this process, the condensate regulating valve 5 located at the lower end of the liquid collecting expansion tube 4 controls the valve opening according to the liquid level height of the liquid pool in the liquid collecting expansion tube 4, so as to adjust the liquid level in the liquid collecting expansion tube 4 to maintain it at a set value, keep the liquid level stable, and prevent saturated steam from penetrating into the third condensate output pipe 6.

[0050] It should be noted that since the heat exchange tube bundle 11 is a U-shaped tube bundle, the heat exchange tube bundle 11 is divided into a first pass tube bundle and a second pass tube bundle according to the flow direction of the saturated steam. Specifically, the upper part of the heat exchange tube bundle 11 first connected to the upper chamber of the tube box 10 is used as the first pass tube bundle, and the lower part is used as the second pass tube bundle.

[0051] The above-described embodiment is only a preferred solution of the present invention, but it is not intended to limit the present invention. A person skilled in the relevant technical field may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, any technical solution obtained by equivalent replacement or equivalent transformation falls within the protection scope of the present invention.

Claims

1. A condensate self-flowing low-temperature gas U-tube heater, characterized in that: It comprises a liquid collecting expansion tube (4) and a horizontal U-tube heat exchanger (9); The horizontal U-tube heat exchanger (9) comprises a tube box (10) located on the left side and a heat exchanger shell (12) located on the right side, the tube box (10) and the heat exchanger shell (12) are not connected to each other; a U-shaped heat exchange tube bundle (11) with an opening facing left is arranged in the heat exchanger shell (12), and a low-temperature gas channel is formed between the outer wall of the heat exchange tube bundle (11) and the inner wall of the heat exchanger shell (12); the lower side wall of the heat exchanger shell (12) is connected to the shell-side inlet pipe (7), and the upper side wall is connected to the shell-side outlet pipe (8); the openings at both ends of the heat exchange tube bundle (11) extend into the tube box (8), are connected to the inner cavity of the tube box (8) and form a steam channel; the low-temperature gas channel and the steam channel are not connected to each other and heat exchange can be achieved through the heat exchange tube bundle (11); the inner cavity of the tube box (10) is divided by a condensate collecting partition plate (16) The partition is an upper chamber and a lower chamber which are not connected to each other, and the openings at both ends of the heat exchange tube bundle (11) are respectively located in the upper chamber and the lower chamber; the condensate collecting partition plate (16) is arranged horizontally and the middle part is recessed downward for collecting condensate, and a first-pass condensate outlet (14) is provided at the recessed part and is connected to the air cavity of the liquid collecting expansion tube (4) through a first condensate output pipeline (2); a second-pass condensate outlet (15) is provided at the bottom of the lower chamber and is connected to the air cavity of the liquid collecting expansion tube (4) through a second condensate output pipeline (3); a steam inlet (13) is provided at the top of the upper chamber and is connected to the steam inlet pipeline (1), and the air cavity of the liquid collecting expansion tube (4) is connected to the steam inlet (13) through a pipeline; the bottom of the liquid pool of the liquid collecting expansion tube (4) is connected to a third condensate output pipeline (6) provided with a condensate regulating valve (5).

2. A condensate self-flowing low-temperature gas U-tube heater according to claim 1, characterized in that: The tube box (10), the heat exchange tube bundle (11) and the heat exchanger shell (12) are coaxially arranged.

3. The condensate self-flowing low-temperature gas U-tube heater according to claim 1, characterized in that: The condensate collecting partition plate (16) is arranged in the middle of the inner cavity of the pipe box (10), and has a square groove in the middle.

4. The condensate self-flowing low-temperature gas U-tube heater according to claim 1, characterized in that: The horizontal U-tube heat exchanger (9) is tilted to the left as a whole to facilitate condensate collection.

5. The condensate self-flowing low-temperature gas U-tube heater according to claim 1, characterized in that: The pipe box (10) and the heat exchanger shell (12) are connected via a flange.

6. The condensate self-flowing low-temperature gas U-tube heater according to claim 1, characterized in that: The liquid collecting and expanding tube (4) is a vertically arranged tube structure, the upper part of which is an air cavity and the lower part of which is a liquid pool.

7. The condensate self-flowing low-temperature gas U-tube heater according to claim 1, characterized in that: A liquid level meter is arranged inside the liquid collection expansion tube (4); the liquid level meter is connected to the condensate regulating valve (5) via a signal line and is used to adjust the valve opening according to the feedback of the liquid level in the liquid pool.

8. The condensate self-flowing low-temperature gas U-tube heater according to claim 1, characterized in that: The pipe box (10) and the heat exchanger shell (12) are both U-shaped structures with openings and closed.

9. A method for extracting condensate using the condensate gravity-flow low-temperature gas U-tube heater according to any one of claims 1 to 8, characterized in that: The details are as follows: During the heat exchange process, low temperature gas and saturated steam are simultaneously introduced into the horizontal U-tube heat exchanger (9), as follows: Saturated steam enters the upper chamber of the tube box (10) through the steam inlet (13) from the steam inlet pipe (1), and then enters the inner cavity of the heat exchange tube bundle (11); at the same time, low-temperature gas enters the heat exchanger shell (12) through the shell inlet pipe (7); saturated steam and low-temperature gas exchange heat at the heat exchange tube bundle (11), and the saturated steam in the heat exchange tube bundle (11) is heat exchanged and condensed; part of the condensate in the first-pass tube bundle of the heat exchange tube bundle (11) flows back and collects in the sunken depression of the condensate collection partition plate (16), and the condensate is evacuated to the liquid collection expansion tube (4) through the first-pass condensate outlet (14) located at the lowest end of the sunken depression through the first condensate output pipe (2); the condensate in the second-pass tube bundle of the heat exchange tube bundle (11) is evacuated to the liquid collection expansion tube (4) through the second condensate output pipe (3) through the second-pass condensate outlet (15) located at the lowest point of the tube box (10); In this process, the condensate regulating valve (5) located at the lower end of the liquid collecting expansion pipe (4) controls the valve opening according to the liquid level height of the liquid pool in the liquid collecting expansion pipe (4), so as to adjust the liquid level in the liquid collecting expansion pipe (4) to maintain it at a set value, thereby preventing saturated steam from penetrating into the third condensate output pipe (6).

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