A condensate removal system for steam reboiler operating condition changes and an operation method thereof

Abstract

The present invention relates to the technical field of condensate discharge system, and in particular to a condensate discharge system for changing the working condition of a steam reboiler and an operation method thereof, wherein the condensate discharge system comprises a condensate water level adjustment tank, a condensate tank and a condensate discharge tank, wherein the top of the steam reboiler is connected to the top of the condensate water level adjustment tank through a steam pipe 1; the steam pipe 1 is connected to the common steam through a steam pipe 2, a steam pneumatic regulating valve is arranged on the steam pipe 2, the steam pipe 2 is connected to the condensate discharge tank through a steam pipe 3, a steam pneumatic switch valve 1 is arranged on the steam pipe 3; the bottom of the steam reboiler is connected to the bottom of the condensate water level adjustment tank through a pipe 1, the pipe 1 is connected to the condensate tank through a pipe 2, the top of the condensate tank is connected to the condensate discharge tank through a pipe 4, and a pressure-balanced pneumatic switch valve is arranged on the pipe 4. When the condensate pressure is insufficient, the present invention uses steam as the power for condensate discharge to press the water in the condensate tank out.

Description

Technical Field

[0001] The present invention relates to the technical field of condensate removal systems, and in particular to a condensate removal system for coping with operating condition changes of a heat pump distillation low-pressure steam reboiler and an operating method thereof. Background Art

[0002] At present, the reboiler condensate discharge system used in engineering is designed according to the theoretical design conditions of the reboiler. When the conditions change, the temperature of the tower kettle decreases, resulting in a decrease in the heating steam pressure and condensate pressure. The condensate cannot be discharged, and the condensate level in the reboiler can only rise, the pressure increases, occupying the heat exchange area, and the steam pressure increases to re-establish the balance. At this time, because the condensate pressure is high and the effective area of ​​the reboiler is small, it belongs to a small area and large temperature difference heat exchange. The temperature and pressure fluctuations of the steam are high relative to the initial theoretical state, which has a greater interference with the heat exchange and affects the stable operation.

[0003] In the heat pump distillation process, the tower bottom reboiler usually retains a small load auxiliary reboiler, which is heated by steam to ensure that the distillation tower is started up and used as a supplement for the stable operation of the heat pump unit. The reboiler is generally designed to use steam temperature 20~30℃ higher than the tower bottom temperature of the distillation tower. For processes with a tower bottom temperature below 100℃, the steam condensate pressure is 1~2barG, which is converted into a water column with a height of no more than 20m. The condensate level in the reboiler is adjusted by controlling the discharge of condensate through a regulating valve, that is, the area of ​​the heat exchange tube occupied by condensate is equivalent to adjusting the heat exchange area, so as to achieve stable regulation of the reboiler load.

[0004] In chemical systems, the steam condensate from multiple reboilers is generally collected into a condensate tank. In order to ensure that the external condensate pump does not cavitate, the condensate tank is generally placed high; the condensate main pipe is higher than the condensate tank and is arranged on the pipe gallery. The above settings cause the condensate pipes of each reboiler to climb much higher. If the condensate is not discharged smoothly, it will occupy the area of ​​the heat exchanger, causing the temperature, pressure, pressure reducing valve opening of the reboiler to deviate significantly from the design point, and the adjustment capacity is insufficient.

[0005] At the same time, the load of the distillation tower is affected by many factors, such as upstream process output, raw material procurement, raw material storage tank inventory and planned processing cycle. In actual engineering operation, the processing capacity is reduced to half of the original design. There are also processes in which multiple raw materials enter the tower, and the overall components are offset. At this time, in order to produce products of qualified purity, the method of lowering the temperature in the tower may be adopted. The reduction in load and temperature will cause the steam pressure to drop, and the condensate pressure will be insufficient and cannot be discharged. Neither the designer nor the user can make a completely accurate prediction of the above load changes in advance. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides a condensate removal system and an operation method thereof for coping with operating condition changes of a heat pump distillation low-pressure steam reboiler.

[0007] The technical solution of the present invention to solve the above technical problems is as follows:

[0008] The first object of the present invention is to provide a condensate discharge system for a steam reboiler with a change in operating condition, comprising a distillation tower and a steam reboiler, wherein the distillation tower is connected to the steam reboiler through inlet and outlet pipelines, and further comprises a condensate level adjustment tank, a condensate tank and a condensate discharge tank, wherein the top of the steam reboiler is connected to the top of the condensate level adjustment tank through a steam pipe 1; the steam pipe 1 is connected to the common steam through a steam pipe 2, a steam pneumatic regulating valve is provided on the steam pipe 2, the steam pipe 2 is connected to the condensate discharge tank through a steam pipe 3, a steam pneumatic switch valve 1 is provided on the steam pipe 3; the steam reboiler The bottom of the condensate tank is connected to the bottom of the condensate water level adjustment tank through pipeline one, and the pipeline one is connected to the condensate tank through pipeline two; the top of the condensate tank is connected to the condensate drain tank through pipeline four, and the pipeline four is provided with a pressure-balancing pneumatic switch valve; the bottom of the condensate tank is connected to the condensate drain tank through pipeline five, and the pipeline five is provided with a condensate drain pneumatic switch valve one; the condensate in the condensate drain tank is discharged through pipeline six to the high-altitude pipe gallery, and the pipeline six is ​​provided with a condensate drain pneumatic switch valve two; the condensate drain tank is connected to a liquid level transmitter two through a pipeline, and the liquid level transmitter two is connected to the condensate drain pneumatic switch valve two through a pipeline.

[0009] By adopting the above technical scheme, the steam reboiler used in the distillation tower uses steam as the heat source, and the condensate generated after the steam condenses is stored in the bottom of the steam reboiler and the condensate water level adjustment tank. The bottom of the steam reboiler and the condensate water level adjustment tank are connected by pipeline 1, and the top is connected to steam pipeline 2. The gas phase pressure is also the same, which is equivalent to a communicating vessel, and the water levels inside the two are the same. By controlling the amount of discharged water, the water level of the condensate water level adjustment tank is stabilized at the target value. According to the principle of communicating vessels, the water level of the steam reboiler is also the same, so that the area of ​​the heat exchange tube exposed above the water surface is stable and controllable, that is, the effect of the steam reboiler is stable and controllable. By setting the condensate tank, the reboiler load adjustment part composed of the steam reboiler and the condensate water level adjustment tank and the low-pressure condensate discharge part composed of the condensate discharge tank and various pneumatic valves can be isolated and do not affect each other, and the condensate discharge operation will not interfere with the stable operation of the steam reboiler, that is, the low-pressure drainage does not affect the regulation of the steam reboiler. The effective volume of the condensate tank is set according to the condensate volume in 3 minutes, so that both the smaller size of the equipment and the less frequent switching of each valve can be taken into account.

[0010] Furthermore, a condensate discharge pneumatic regulating valve is provided on the second pipeline, the condensate discharge pneumatic regulating valve is connected to the condensate tank via the third pipeline, and a liquid level transmitter 1 is provided on the third pipeline.

[0011] By adopting the above technical solution, the liquid level transmitter and the condensate discharge pneumatic regulating valve are interlocked, and then the water level of the condensate level adjustment tank is stabilized at the target value by controlling the discharge water volume.

[0012] Furthermore, a steam constant pressure valve is provided on the steam pipeline three, and the steam constant pressure valve is located between the steam pneumatic switch valve one and the condensate tank.

[0013] By adopting the above technical solution and setting a steam constant pressure valve, no matter how much steam pressure is used to drain the condensate, the actual pressure acting on the condensate tank remains unchanged, which ensures that the time required to drain a tank of condensate is stable, that is, the time period for periodic condensate drainage in the automatic mode is adjustable and stable. If you want to modify this time, you only need to adjust the spring preload of the steam constant pressure valve. This valve comes with an adjustable valve stem and can be operated directly on site without disassembly.

[0014] Furthermore, the steam pipe three is connected to the low-pressure steam through the steam pipe four, and the steam pipe four is provided with a steam pneumatic switch valve two.

[0015] Furthermore, the connection point between the steam pipe 4 and the steam pipe 3 is located between the steam pneumatic switch valve 1 and the steam constant pressure valve.

[0016] By adopting the above technical solution, a variety of steam sources can be used. The steam required for the condensate tank can use the public steam through the steam pneumatic switch valve 1, or use other low-pressure steam through the steam pneumatic switch valve 2, that is, use the waste steam from other devices; the steam source can be determined when the system is designed, and only one of the steam pneumatic switch valve 1 and the steam pneumatic switch valve 2 needs to be installed.

[0017] Furthermore, a steam reboiler pressure gauge is provided on the steam pipeline.

[0018] By adopting the above technical solution, the pressure in the steam pipe 1 is detected at all times.

[0019] Furthermore, a condensate drain tank pressure gauge is provided on the condensate drain tank.

[0020] By adopting the above technical solution, the pressure in the condensate drain tank is detected at all times.

[0021] Furthermore, the steam reboiler is a vertical thermosyphon reboiler.

[0022] Furthermore, the steam constant pressure valve is a mechanical valve.

[0023] By adopting the above technical solution, the pure mechanical valve has no external control requirements, and the pressure is set according to the pressure required for condensate discharge during design and selection.

[0024] A second object of the present invention is to provide an operating method for a condensate removal system for a steam reboiler with a changed operating condition, comprising the following steps:

[0025] When the public steam enters the steam reboiler through the steam pneumatic regulating valve, it has a sufficiently high pressure, that is, the pressure is ≥2barG, the condensate can be discharged smoothly, and the internal operator directly closes the steam pneumatic switch valve 1 in the remote manual mode, and opens the pressure balance pneumatic switch valve, the condensate discharge pneumatic switch valve 1, and the condensate discharge pneumatic switch valve 2, and the condensate is directly discharged;

[0026] When the steam actually used in the steam reboiler after passing through the steam pneumatic regulating valve does not have sufficient pressure, that is, the pressure is less than 2 barG, and the condensate cannot be discharged, the internal operator switches to the remote automatic mode. The automatic mode control logic is:

[0027] S1, the condensate drain pneumatic switch valve 2 is closed, the pressure balance pneumatic switch valve and the condensate drain pneumatic switch valve 1 are opened, and the condensate in the condensate tank enters the condensate drain tank;

[0028] S2. When the water level of the second level transmitter rises to the high point setting value, the pressure balance pneumatic switch valve and the condensate discharge pneumatic switch valve 1 are closed, the steam pneumatic switch valve 1 and the condensate discharge pneumatic switch valve 2 are opened, and the public steam enters the condensate discharge tank after passing through the steam pneumatic switch valve 1, increasing its pressure and pushing out the condensate;

[0029] S3. When the water level of the second level transmitter drops to the low set value, the steam pneumatic switch valve 1 and the condensate drain pneumatic switch valve 2 are closed, the pressure balance pneumatic switch valve and the condensate drain pneumatic switch valve 1 are opened, and the water in the condensate tank falls into the condensate drain tank, and S2 and S3 are repeated in sequence.

[0030] By adopting the above technical solution, the operation logic is simple. In manual mode, the liquid level transmitter 1 is interlocked with the condensate discharge pneumatic regulating valve, and other valves (steam pneumatic switch valve 1, steam pneumatic switch valve 2, pressure balance pneumatic switch valve, steam pneumatic switch valve 1, condensate discharge pneumatic switch valve 2) are fixed and fully open without operation; in automatic mode, it is operated by self-control logic, and the internal operator only needs to judge and select the operation mode. The change of the working load of the distillation tower generates the switching demand, but this change is not frequent. Each change may be separated by several days or even months. In addition, each change itself requires the parameters of the distillation tower to be stabilized again, so the condensate discharge system of the present invention will not increase the operator's workload.

[0031] Furthermore, the public steam passes through the steam pneumatic switch valve 1 and then passes through the steam constant pressure valve to enter the condensate tank.

[0032] In summary, compared with the prior art, the above technical solution has the following beneficial effects:

[0033] The present invention is aimed at the occasions where the temperature of the bottom of the distillation tower is below 100°C, the heat source is low-pressure steam, and it is not conducive to condensate recovery, a typical example being a heat pump distillation system. On the basis of not affecting the regulating capacity of the reboiler, the present invention ensures that the condensate is not affected by the change of the condensate pressure and can be discharged smoothly.

[0034] The principle of the present invention is: when the condensate pressure is sufficient, that is, the pressure is ≥2barG, it is directly discharged; when the condensate pressure is insufficient, that is, the pressure is <2barG, the waste steam with higher pressure from other processes of the user or the steam from public works is used as the power for condensate discharge to pressurize the water in the condensate tank out.

[0035] The present invention takes into account both theoretical design conditions and possible actual low condensate pressure conditions, and at the same time, by providing a condensate tank, ensures that when public steam or low-pressure steam is periodically and discontinuously introduced for drainage, the condensate discharge of the steam reboiler remains continuous, the water level height does not produce periodic fluctuations, and does not affect the heat exchange stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The overall structure of the present invention is shown in FIG. Figure 1 ;

[0037] Figure 2 The overall structure of the present invention is shown in FIG. Figure 2 .

[0038] Explanation of the reference numerals: 1. distillation tower; 2. steam reboiler; 3. condensate level adjustment tank; 4. condensate tank; 5. condensate drain tank; 6. steam reboiler pressure gauge; 7. liquid level transmitter one; 8. condensate drain tank pressure gauge; 9. liquid level transmitter two; 10. steam pneumatic regulating valve; 11. steam pneumatic switch valve one; 12. steam pneumatic switch valve two; 13. steam constant pressure valve; 14. condensate drain pneumatic regulating valve; 15. pressure balance pneumatic switch valve; 16. condensate drain pneumatic switch valve one; 17. condensate drain pneumatic switch valve two; 101. pipeline one; 102. pipeline two; 103. pipeline three; 104. pipeline four; 105. pipeline five; 106. pipeline six; 201. steam pipeline one; 202. steam pipeline two; 203. steam pipeline three; 204. steam pipeline four. DETAILED DESCRIPTION

[0039] The following is combined with Figure 1-2 The principles and features of the present invention are described, and the examples given are only used to explain the present invention, rather than to limit the scope of the present invention.

[0040] The embodiment of the present invention discloses a condensate removal system for a steam reboiler with changing operating conditions.

[0041] Reference Figure 1 and Figure 2 A condensate discharge system for a steam reboiler with a changed operating condition includes a distillation tower 1 and a steam reboiler 2. The distillation tower 1 is connected to the steam reboiler 2 through an inlet and outlet pipeline, and also includes a condensate level adjustment tank 3, a condensate tank 4 and a condensate discharge tank 5. The steam reboiler 2 used in the distillation tower 1 is a vertical thermosyphon reboiler, which uses steam as a heat source. The condensate generated after the steam is condensed is stored at the bottom of the steam reboiler 2 and in the condensate level adjustment tank 3.

[0042] The top of the steam reboiler 2 is connected to the top of the condensate water level adjustment tank 3 through a steam pipe 201, and the bottom of the steam reboiler 2 is connected to the bottom of the condensate water level adjustment tank 3 through a pipe 101. The steam reboiler 2 and the condensate water level adjustment tank 3 have the same gas phase pressure, which is equivalent to a communicating vessel, and the water levels inside the two are at the same height.

[0043] The pipeline 101 is connected to the condensate tank 4 through the pipeline 2 102, and the pipeline 2 102 is equipped with a condensate discharge pneumatic regulating valve 14, and the condensate discharge pneumatic regulating valve 14 is connected to the condensate tank 4 through the pipeline 3 103, and the pipeline 3 103 is equipped with a liquid level transmitter 1 7. The liquid level transmitter 1 7 and the condensate discharge pneumatic regulating valve 14 are interlocked, and the water level of the condensate water level adjustment tank 3 is stabilized at the target value by controlling the discharge water volume. According to the principle of the communicating vessel, the water level of the steam reboiler 2 is also equal in height, so that the area of ​​the heat exchange tube exposed above the water surface is stable and controllable, that is, the effect of the steam reboiler 2 is stable and controllable.

[0044] The top of the condensate tank 4 is connected to the condensate tank 5 through a pipeline 104, and a pressure-balanced pneumatic switch valve 15 is installed on the pipeline 104; the bottom of the condensate tank 4 is connected to the condensate tank 5 through a pipeline 105, and a condensate pneumatic switch valve 16 is installed on the pipeline 105. The condensate in the condensate tank 5 is discharged through a pipeline 106 to the high-altitude pipe gallery, and a condensate pneumatic switch valve 2 17 is installed on the pipeline 106; the condensate tank 5 is connected to a liquid level transmitter 2 9 through a pipeline, and the liquid level transmitter 2 9 is connected to the condensate pneumatic switch valve 2 17 through a pipeline.

[0045] By providing the condensate tank 4, the reboiler load adjustment part composed of the steam reboiler 2 and the condensate water level adjustment tank 3 and the low-pressure condensate discharge part composed of the condensate discharge tank 5 and various pneumatic valves can be isolated and do not affect each other, and the condensate discharge operation will not interfere with the stable operation of the steam reboiler 2, that is, the low-pressure drainage does not affect the regulation of the steam reboiler 2. The effective volume of the condensate tank 4 is set according to the condensate volume of 3 minutes, so that the smaller volume of the equipment and the less frequent opening and closing of each valve can be taken into account at the same time.

[0046] The steam pipe 1 201 is connected to the public steam through the steam pipe 2 202, and a steam pneumatic regulating valve 10 is installed on the steam pipe 2 202. The steam pipe 2 202 is connected to the condensate tank 5 through the steam pipe 3 203, and a steam pneumatic switch valve 11 is installed on the steam pipe 3 203.

[0047] The steam pipe 3 203 is provided with a steam constant pressure valve 13, which is located between the steam pneumatic switch valve 11 and the condensate tank 5. By setting the steam constant pressure valve 13, no matter how much pressure of steam is used to discharge condensate, the actual pressure acting on the condensate tank 5 is constant, which ensures that the time required to discharge a tank of condensate is stable, that is, the time period of periodic condensate discharge in the automatic mode is adjustable and stable. If you want to modify this time, you only need to adjust the spring preload of the steam constant pressure valve 13. This valve has a built-in adjustment valve stem and can be operated directly on site without disassembly.

[0048] The steam constant pressure valve 13 is a pure mechanical valve, which has no external control requirements. During the design and selection, the pressure is set according to the pressure required for condensate discharge.

[0049] The steam pipe three 203 is connected to low-pressure steam through the steam pipe four 204. The steam pipe four 204 is installed with a steam pneumatic switch valve two 12. The connection between the steam pipe four 204 and the steam pipe three 203 is located between the steam pneumatic switch valve one 11 and the steam constant pressure valve 13. Through the above arrangement, multiple steam sources can be used. The steam required by the condensate tank 5 can use the public steam through the steam pneumatic switch valve one 11, and can also use other low-pressure steam through the steam pneumatic switch valve two 12, that is, use the waste steam of other devices; the steam source can be determined when the system is designed, and only one of the steam pneumatic switch valve one 11 and the steam pneumatic switch valve two 12 can be installed.

[0050] The steam pipe 201 is provided with a steam reboiler pressure gauge 6 to detect the pressure in the steam pipe 201 at all times. The condensate tank 5 is provided with a condensate tank pressure gauge 8 to detect the pressure in the condensate tank 5 at all times.

[0051] The embodiment of the present invention further discloses an operation method of the condensate removal system for a steam reboiler with a changed operating condition as described above.

[0052] Reference Figure 1 and Figure 2 , a method for operating a condensate removal system for a steam reboiler with a changed operating condition as described above, comprising the following steps:

[0053] When the common steam enters the steam reboiler 2 through the steam pneumatic regulating valve 10, it has a sufficiently high pressure, that is, the pressure is ≥ 2 barG, and the condensate can be discharged smoothly. The internal operator directly closes the steam pneumatic switch valve 11 in the remote manual mode, and opens the pressure balance pneumatic switch valve 15, the condensate discharge pneumatic switch valve 1 16, and the condensate discharge pneumatic switch valve 2 17, and the condensate is directly discharged;

[0054] When the steam actually used in the steam reboiler 2 after passing through the steam pneumatic regulating valve 10 does not have sufficient pressure, that is, the pressure is less than 2 barG, and the condensate cannot be discharged, the internal operator switches to the remote automatic mode. The automatic mode control logic is:

[0055] S1, the condensate drain pneumatic switch valve 2 17 is closed, the pressure balance pneumatic switch valve 15 and the condensate drain pneumatic switch valve 1 16 are opened, and the condensate in the condensate tank 4 enters the condensate drain tank 5;

[0056] S2. When the water level of the liquid level transmitter 29 rises to the high point setting value, the pressure balance pneumatic switch valve 15 and the condensate discharge pneumatic switch valve 16 are closed, the steam pneumatic switch valve 11 and the condensate discharge pneumatic switch valve 2 17 are opened, and the public steam passes through the steam pneumatic switch valve 11 and then through the steam constant pressure valve 13 into the condensate discharge tank 5, increasing its pressure and pushing out the condensate;

[0057] S3. When the water level of the liquid level transmitter 29 drops to the low set value, the steam pneumatic switch valve 11 and the condensate discharge pneumatic switch valve 2 17 are closed, the pressure balance pneumatic switch valve 15 and the condensate discharge pneumatic switch valve 16 are opened, and the water in the condensate tank 4 falls into the condensate discharge tank 5, and S2 and S3 are repeated in sequence.

[0058] The principle of the present invention is: when the condensate pressure is sufficient, that is, the pressure is ≥2barG, it is directly discharged; when the condensate pressure is insufficient, that is, the pressure is <2barG, the waste steam with higher pressure from other processes of the user or the steam from public works is used as the power for condensate discharge to pressurize the water in the condensate tank 4 out.

[0059] The operation logic of the present invention is simple. In manual mode, the liquid level transmitter 17 and the condensate drain pneumatic regulating valve 14 are interlocked, and other valves (steam pneumatic switch valve 11, steam pneumatic switch valve 2 12, pressure balance pneumatic switch valve 15, steam pneumatic switch valve 11, condensate drain pneumatic switch valve 2 17) are fixed and fully open without operation; in automatic mode, it is operated by self-control logic, and the internal operator only needs to judge and select the operation mode.

[0060] For example:

[0061] A distillation tower 1 for separation of light hydrocarbons was originally designed to handle 750,000 tons of gas per year, with a bottom temperature of 99°C. One feed of distillation tower 1 was purchased liquefied gas with a lighter component, and the other was a plant storage tank that was processed by an upstream tower with a heavier component. During actual operation, due to changes in the market environment, the feed of external liquefied gas was greatly reduced, and at the same time, the sales price of downstream products dropped, and the production capacity dropped, and the total processing capacity of distillation tower 1 was reduced to 380,000 tons / year. At this time, the proportion of external liquefied gas with lighter components decreased, and the overall components became heavier, deviating from the design conditions of distillation tower 1. In order to reduce the content of pentane in the produced butane and ensure the product is qualified, the reflux rate was increased and the bottom temperature was reduced to 77°C. The actual steam pressure of steam reboiler 2 was reduced to 0.8 barG, drainage was not smooth, and the water level rose to 72% of steam reboiler 2, that is, the effective heat exchangeable area was only 28%.

[0062] After it was clear that this state would not change in a short time, the internal operator switched the system to automatic mode, and the on-site external operator adjusted the steam constant pressure valve 13 to 1.2 barG. The rear condensate discharge cycle was about 2 minutes and 40 seconds, and the water level in the steam reboiler 2 was 19%.

[0063] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A condensate removal system for a steam reboiler with a changed operating condition, comprising a distillation tower (1) and a steam reboiler (2), wherein the distillation tower (1) is connected to the steam reboiler (2) via an inlet and an outlet pipeline, and characterized in that: The steam reboiler (2) also comprises a condensate level adjustment tank (3), a condensate tank (4) and a condensate discharge tank (5); the top of the steam reboiler (2) is connected to the top of the condensate level adjustment tank (3) via a steam pipe (201); the steam pipe (201) is connected to the common steam via a steam pipe (202); a steam pneumatic regulating valve (10) is provided on the steam pipe (202); the steam pipe (202) is connected to the condensate discharge tank (5) via a steam pipe (203); a steam pneumatic switch valve (11) is provided on the steam pipe (203); the bottom of the steam reboiler (2) is connected to the bottom of the condensate level adjustment tank (3) via a pipe (101); the pipe (101 ... The second pipeline (102) is connected to the condensate tank (4); the top of the condensate tank (4) is connected to the condensate drain tank (5) through the fourth pipeline (104), and the fourth pipeline (104) is provided with a pressure-balanced pneumatic switch valve (15); the bottom of the condensate tank (4) is connected to the condensate drain tank (5) through the fifth pipeline (105), and the fifth pipeline (105) is provided with a condensate drain pneumatic switch valve (16); the condensate in the condensate drain tank (5) is discharged through the sixth pipeline (106), and the sixth pipeline (106) is provided with a condensate drain pneumatic switch valve (2) (17); the condensate drain tank (5) is connected to the second liquid level transmitter (9) through the pipeline, and the second liquid level transmitter (9) is connected to the second condensate drain pneumatic switch valve (17) through the pipeline.

2. The condensate removal system for steam reboiler operating condition changes according to claim 1, characterized in that: The pipeline 2 (102) is provided with a condensate discharge pneumatic regulating valve (14), the condensate discharge pneumatic regulating valve (14) is connected to the condensate tank (4) via the pipeline 3 (103), and the pipeline 3 (103) is provided with a liquid level transmitter 1 (7).

3. The condensate removal system for steam reboiler operating condition changes according to claim 1, characterized in that: The steam pipe three (203) is provided with a steam constant pressure valve (13), and the steam constant pressure valve (13) is located between the steam pneumatic switch valve one (11) and the condensate tank (5).

4. The condensate removal system for steam reboiler operating condition changes according to claim 3, characterized in that: The steam pipe three (203) is connected to the low-pressure steam through the steam pipe four (204), and the steam pipe four (204) is provided with a steam pneumatic switch valve two (12).

5. The condensate removal system for steam reboiler operating condition changes according to claim 4, characterized in that: The connection point between the steam pipe four (204) and the steam pipe three (203) is located between the steam pneumatic switch valve one (11) and the steam constant pressure valve (13).

6. The condensate removal system for steam reboiler operating condition changes according to claim 1, characterized in that: The steam pipe 1 (201) is provided with a steam reboiler pressure gauge (6), and the condensate drain tank (5) is provided with a condensate drain tank pressure gauge (8).

7. The condensate removal system for steam reboiler operating condition changes according to claim 1, characterized in that: The steam reboiler (2) is a vertical thermosyphon reboiler.

8. The condensate removal system for steam reboiler operating condition changes according to claim 3, characterized in that: The steam constant pressure valve (13) is a mechanical valve.

9. An operating method for a condensate removal system for a steam reboiler with a changed operating condition as claimed in any one of claims 1 to 8, characterized in that: The steps include: When the common steam enters the steam reboiler (2) through the steam pneumatic regulating valve (10), and the pressure is ≥ 2 barG, the condensate can be discharged smoothly. The operator closes the steam pneumatic switch valve 1 (11) in the remote manual mode, and opens the pressure balance pneumatic switch valve (15), the condensate discharge pneumatic switch valve 1 (16), and the condensate discharge pneumatic switch valve 2 (17), so that the condensate is directly discharged; When the steam pressure actually used by the steam reboiler (2) after passing through the steam pneumatic control valve (10) is less than 2 barG and the condensate cannot be discharged, the internal operator switches to the remote automatic mode. The control logic of the automatic mode is: S1, the condensate drain pneumatic switch valve 2 (17) is closed, the pressure balance pneumatic switch valve (15) and the condensate drain pneumatic switch valve 1 (16) are opened, and the condensate in the condensate tank (4) enters the condensate drain tank (5); S2. When the water level of the second level transmitter (9) rises to the high point setting value, the pressure balance pneumatic switch valve (15) and the condensate discharge pneumatic switch valve (16) are closed, the steam pneumatic switch valve (11) and the condensate discharge pneumatic switch valve (17) are opened, and the public steam passes through the steam pneumatic switch valve (11) and enters the condensate discharge tank (5), increasing its pressure and pushing out the condensate; S3. When the water level of the second level transmitter (9) drops to the low set value, the steam pneumatic switch valve (11) and the condensate drain pneumatic switch valve (17) are closed, the pressure balance pneumatic switch valve (15) and the condensate drain pneumatic switch valve (16) are opened, and the water in the condensate tank (4) falls into the condensate drain tank (5), and S2 and S3 are repeated in sequence.

10. The method for operating a condensate removal system for a steam reboiler with a changed operating condition according to claim 9, characterized in that: The public steam passes through the steam pneumatic switch valve 1 (11) and then passes through the steam constant pressure valve (13) to enter the condensate drain tank (5).

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