A comprehensive recovery and utilization system for process condensate energy

Abstract

The invention discloses a comprehensive energy recovery and utilization system for process condensate. Low-speed gas is cooled by low-speed gas heat exchanger A and low-speed gas heat exchanger B in sequence and then enters low-speed gas separator. The process condensate separated by the low-speed gas separator is pressurized by a process condensate pump and then preheated by low-speed gas heat exchanger A and process condensate heat exchanger in sequence and then enters a stripping tower. The cold side outlet pipeline of the process condensate heat exchanger is divided into two branches, one of which goes to the boiler feed water pump outlet main pipe, and the desalted water in the desalted water tank goes to the cold side inlet pipeline of low-speed gas heat exchanger B through the desalted water pump. The hot side outlet pipeline of low-speed gas heat exchanger B is divided into two branches, one of which goes to a deoxidizer, and the other goes to a lithium bromide heat exchange unit and then returns to the cold side inlet pipeline of low-speed gas heat exchanger B. The top steam of the deoxidizer enters the lithium bromide heat exchange unit to recover waste heat. It achieves the purpose of energy saving and consumption reduction, and at the same time makes the system run stably.

Description

Technical Field

[0001] The invention relates to the technical field of synthetic ammonia, and in particular to a comprehensive recovery and utilization system of process condensate energy. Background Art

[0002] The overall process flow of the synthetic ammonia process in a nitrogen fertilizer plant is as follows: external natural gas is metered, pressure-regulated, and impurity-removed, compressed to 4.08MPa by a centrifugal natural gas compressor, and then heated for high-temperature desulfurization, heat exchange conversion, two-stage steam reforming, high-low conversion of carbon monoxide, removal of carbon dioxide, deep methanation purification, synthesis gas cycle gas compression, ammonia synthesis, and cryogenic separation to finally obtain the product liquid ammonia.

[0003] The process condensate separated from the low-gas separator contains trace amounts of ammonia, carbon dioxide and alcohols, such as Figure 1 As shown, after being pressurized by the process condensate pump 5, it is preheated to about 234°C in the process condensate heat exchanger 2, enters the top of the process condensate stripping tower 3, and flows from top to bottom through the packed bed layer in the tower. The medium-pressure superheated steam from the medium-pressure steam network enters from the bottom of the process condensate stripping tower, contacts with the process condensate in the packing layer in countercurrent, and strips out the dissolved trace ammonia, carbon dioxide and alcohol. The steam coming out of the top of the stripping tower is sent to the conversion process as process steam. The low-gas separator 4 is provided with an emergency discharge valve, which forms a layered control mode with the outlet regulating valve of the process condensate pump 5. Under normal circumstances, only the outlet regulating valve of the process condensate pump 5 is opened to automatically control the liquid level of the low-gas separator. When the process condensate pump jumps or other reasons cause the liquid level to be higher than the set value, the emergency discharge valve is automatically opened to discharge the process condensate to the circulating water pool to control the normal liquid level of the low-gas separator. The qualified process condensate after stripping is sent to the desalted water tank 7 of the desalted water station after the process condensate heat exchanger 2 recovers heat and the process condensate cooler 6 cools it. The process condensate after stripping is equipped with an online conductivity analyzer. When the conductivity is unqualified and reaches the interlock setting value during the start-up, shutdown or production process, the process of interlock switching cut-off valve 8 / 9 is automatically triggered to discharge the unqualified process condensate into the circulating water pool. The superheated steam flow meter entering the stripping tower is equipped with a low flow alarm, and the liquid level of the stripping tower is equipped with a high and low liquid level alarm. The process condensate after stripping is designed to have a high conductivity alarm after heat exchange in the process condensate heat exchanger. At the same time, a manual analysis sampling point for process condensate is set on site.

[0004] The top gas outlet of the low-gas shift separator goes to the carbon dioxide absorption tower. The inlet temperature of the CO2 absorption tower is cooled by heat exchange of desalted water in the low-gas shift heat exchanger. The temperature of the desalted water after heat exchange is about 120°C. The desalted water after the low-gas shift heat exchanger enters from the top of the deaerator 10, flows from top to bottom through the packing bed in the tower, and countercurrently contacts with the low-pressure steam added from the bottom for physical deoxygenation. To ensure continuous deoxygenation, the deaerator must be emptied continuously to release the oxygen analyzed by steam. The qualified deoxygenated water is pressurized by the boiler feed pump and then used to produce steam in each boiler of the device.

[0005] Problems with this process:

[0006] The heat of the process condensate is not reasonably utilized. Circulating water is needed to cool the industrial condensate condenser, which also causes a large amount of circulating water consumption and water waste due to evaporation of circulating water.

[0007] The pressure of the process condensate is relatively high (pressure 3.8Mpa, temperature 102℃, flow rate 30t / h). After being reduced in pressure and cooled, it is sent to the desalted water station, and then needs to be pressurized twice by a pump before being sent out for use as desalted water. The pressure potential energy of the process condensate is not reasonably utilized, and the secondary pressurization after reducing the pressure to normal pressure consumes electricity again.

[0008] The amount of desalted water passing through the low-gas heat exchanger is greatly affected by the system load fluctuations. When the device is started or stopped or the production load fluctuates, the inlet temperature of the CO2 absorption tower cannot be controlled, causing the water balance of the decarbonization system to be affected. It is necessary to drain or replenish water from the decarbonization system to maintain the water balance of the decarbonization system.

[0009] The deaerator steam (pressure 0.25Mpa, flow rate 0.8t / h saturated steam) is directly vented, the water is wasted, the steam venting causes great visual pollution, and the heat of the steam directly vented cannot be utilized. Summary of the invention

[0010] In view of the shortcomings of the prior art, the present invention provides a comprehensive recovery and utilization system for process condensate energy, which saves energy and reduces consumption while enabling the entire system to operate stably and reliably.

[0011] To achieve the above objectives, the present invention is implemented through the following technical solutions: a process condensate energy comprehensive recovery and utilization system, including a stripping tower, a low-shift gas separator, a deaerator, a desalted water tank, a process condensate heat exchanger and a low-shift gas heat exchanger, characterized in that: the low-shift gas heat exchanger includes a low-shift gas heat exchanger A and a low-shift gas heat exchanger B, the low-shift gas from the carbon dioxide reboiler passes through the low-shift gas heat exchanger A and the low-shift gas heat exchanger B in turn and then enters the low-shift gas separator from the top of the low-shift gas separator after being cooled, the top gas outlet pipeline of the low-shift gas separator goes to the carbon dioxide absorption tower, the process condensate separated by the low-shift gas separator comes out from the bottom, and passes through the process condenser After the liquid pump is pressurized, it passes through the low-change gas heat exchanger A and the process condensate heat exchanger for preheating in turn and enters the stripping tower from the top of the stripping tower. The lower part of the stripping tower is provided with a medium-pressure steam inlet. The gas outlet pipeline at the top of the stripping tower goes to the conversion system. The process condensate coming out of the bottom process condensate outlet pipeline is cooled by the process condensate heat exchanger and then comes out from the cold side outlet pipeline of the process condensate heat exchanger. The cold side outlet pipeline of the process condensate heat exchanger is divided into two branches, one of which goes to the boiler feed water pump outlet main pipe, and a first automatic regulating valve and a process condensate booster pump are arranged on the branch pipe, and the other branch goes to the circulating water tank, and a second automatic regulating valve is arranged on the branch pipe;

[0012] The desalted water in the desalted water tank is pumped to the cold side inlet pipeline of the low-gas-change gas heat exchanger B. The hot side outlet pipeline of the low-gas-change gas heat exchanger B is divided into two branches, one of which is used for the deaerator, and the other is used for the lithium bromide heat exchanger unit to recover waste heat and produce low-pressure steam. The desalted water after recovering the waste heat is returned to the cold side inlet pipeline of the low-gas-change gas heat exchanger B through the desalted water circulation pump. The top steam of the deaerator enters the lithium bromide heat exchanger unit to recover waste heat and produce low-pressure steam. The water inlet pipe of the lithium bromide heat exchanger unit is connected to the outlet main pipe of the boiler feed water pump.

[0013] The qualified process condensate after stripping comes out from the bottom of the stripping tower, recovers heat through the process condensate heat exchanger, and is pressurized by the process condensate booster pump and sent to the boiler feed water pump outlet main pipe, which fully utilizes the pressure potential energy of the process condensate itself. The process condensate is no longer cooled, and the heat of the process condensate is also fully recovered and utilized.

[0014] The process condensate cooler is no longer used to condense the process condensate, reducing the amount of circulating water (circulating water for the process condensate cooler). The first automatic regulating valve is set at the outlet of the process condensate booster pump, and forms a layered control method with the second automatic regulating valve. The high interlock output condition of the process condensate conductivity is that when the interlock reaches the set value, the process condensate booster pump is automatically stopped and the first automatic regulating valve is closed. The second automatic regulating valve is automatically opened to 30% of the valve position for 3 seconds, and then automatically switched to automatically control the liquid level of the stripping tower. The superheated steam flowmeter of the stripping tower is still equipped with a low flow alarm, and the liquid level of the stripping tower is equipped with a high and low liquid level alarm.

[0015] Since the qualified process condensate of stripping is directly sent to the outlet of boiler feed water pump, the amount of desalted water entering the deaerator after heat exchange in the low-gas heat exchanger is reduced. When the desalted water passing through the low-gas heat exchanger is reduced, the inlet temperature of the absorption tower will be high. In order to reduce and control the inlet temperature of the CO2 absorption tower, the present invention sets two low-gas-to-low-gas heat exchangers. The temperature of the process condensate separated from the low-gas separator is about 81°C. After being pressurized by the process condensate pump, it is first heat exchanged in the low-gas process condensate heat exchanger A to increase the temperature to above 115°C, and then sent to the process condensate heat exchanger for heat exchange, so as to reduce the heat exchange amount entering the low-gas heat exchanger B, and the temperature of the qualified process condensate of stripping coming out of the process condensate heat exchanger is increased from 102°C to about 135°C, and these low-grade heat are finally transferred to the boiler feed water.

[0016] When the amount of desalted water added to the deaerator is reduced, the amount of steam added to the deaerator will be reduced, and the amount of steam venting from the deaerator will be reduced from 0.8t / h before the transformation to about 0.5t / h, but there is still steam venting loss. In order to make full use of the heat of this part of the steam venting and reduce water waste, as well as the heat of the desalted water circulating through the low-gas heat exchanger, a lithium bromide heat exchanger unit is set to recover the waste heat of these two parts. The deaerator venting steam is introduced into the lithium bromide heat exchanger unit, and after the heat is recovered, it becomes steam condensate and is sent to the water tank of the evaporative ammonia condenser in the device, realizing the recovery of steam condensate. The circulating desalted water first recovers heat through the lithium bromide heat exchanger unit, and then returns to the inlet of the low-gas heat exchanger B after being pressurized by the desalted water circulation pump, completing the circulation process of the desalted water and the recovery of heat at the same time. After the two parts of heat are recovered in the lithium bromide unit, they are used to generate low-pressure steam of about 0.4Mpa, and the low-pressure steam is transported to the low-pressure steam main in the device. The water used to produce steam in the lithium bromide unit comes from the boiler water at the outlet of the boiler feed pump.

[0017] In the above scheme: in order to control the inlet temperature of the CO2 absorption tower, realize automatic control of the inlet temperature of the CO2 absorption tower, increase the flow of desalted water passing through the low-temperature gas heat exchanger B, and set a third automatic regulating valve at the outlet of the desalted water circulation pump.

[0018] In the above scheme, the outlet of the process condensate pump is provided with a fourth automatic regulating valve. The low-gas separator is provided with an emergency discharge valve, which forms a hierarchical control mode with the fourth automatic regulating valve. Under normal circumstances, only the fourth automatic regulating valve at the outlet of the process condensate pump is opened to automatically control the liquid level of the low-gas separator. When the process condensate pump jumps or other reasons cause the liquid level to be higher than the set value, the emergency discharge valve is automatically opened to discharge the process condensate into the circulating water pool to control the normal liquid level of the low-gas separator.

[0019] In the above scheme: a flow meter and a pressure gauge are provided on the outlet main pipe of the boiler feed water pump, a small flow boiler feed water pump and a large flow boiler feed water pump with simultaneous low flow and pressure interlocking start-up as a standby are provided on the outlet pipe of the deaerator, and the outlets of the large flow boiler feed water pump with simultaneous low flow and pressure interlocking start-up as a standby and the small flow boiler feed water pump are both connected to the outlet main pipe of the boiler feed water pump; during normal operation, the process condensate booster pump and the small flow boiler feed water pump operate simultaneously, and when the process condensate booster pump and the small flow boiler feed water pump cause the boiler feed water to be interrupted due to jumping or other reasons, the large flow boiler feed water pump with simultaneous low flow and pressure interlocking start-up as a standby is started. When the process condensate is sent directly to the outlet of the original boiler feed pump, the flow rate of the original boiler feed pump is reduced, which will cause the efficiency of the original boiler feed pump to decrease. Therefore, the original boiler feed pump is replaced with a small-flow boiler feed pump (in principle, one group of two is designed, and only one is drawn in the figure). During normal production, the process condensate booster pump and the small-flow boiler feed pump are used at the same time to meet the normal water requirements of production.

[0020] In the above scheme: the outlet main pipe of the boiler feed water pump is also provided with a low flow pressure alarm device to remind the operator to find problems in time.

[0021] In the above scheme: a fifth automatic regulating valve is arranged on the water inlet pipe of the lithium bromide heat exchange unit to automatically control the liquid level of the boiler in the lithium bromide unit.

[0022] The water inlet pipe of the lithium bromide heat exchange unit is provided with a liquid level high and low alarm device.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The process condensate flow rate is 30t / h without reducing the pressure. It is directly pressurized by the process condensate booster pump and used as boiler water, which can save about 50KW / h of electricity consumption of the boiler feed pump. Calculated based on an annual operating time of 8,000 hours, it can save 400,000 KWh of electricity consumption each year.

[0025] 2. The process condensate is heat exchanged in the low-gas process condensate heat exchanger and then enters the process condensate heat exchanger. The qualified process condensate flow rate is 30t / h, and the temperature is increased from 102℃ to about 135℃. At the same time, the process condensate is no longer cooled after the transformation. After the heat is recovered into the boiler feed water, the production of 4.0Mpa medium-pressure steam can be increased by about 5.5t / h. Calculated based on an annual operating time of 8,000 hours, the annual production of medium-pressure steam can be increased by 44,000 tons.

[0026] 3. The deaerator vent steam and the heat of the circulating desalted water are used to produce low-pressure steam, increasing the production of low-pressure steam by about 4t / h. Based on an annual operating time of 8,000 hours, the annual production of low-pressure steam can be increased by 32,000 tons.

[0027] 4. After the transformation, the inlet temperature of the CO2 absorption tower can be effectively and automatically controlled online. Calculated based on an annual operating time of 8,000 hours, the acidic water discharge of the decarbonization system can be reduced by about 5,000 tons per year, the steam condensate discharged from the deaerator can be recovered by about 4,000 tons per year, and the steam venting loss of the deaerator can be reduced by about 2,400 tons per year.

[0028] 5. After the process transformation, the corresponding interlocking control system is added to greatly improve the reliability and stability of the device operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is the process flow chart before transformation of the present invention.

[0030] Figure 2 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0031] The present invention will be further described below in conjunction with embodiments and drawings.

[0032] like Figure 1 As shown, the process condensate energy comprehensive recovery and utilization system of the present invention is composed of a fifth automatic regulating valve 1, a process condensate heat exchanger 2, a stripping tower 3, a low-gas-shift separator 4, a process condensate pump 5, a desalted water tank 7, a deaerator 10, a gas-shift heat exchanger A11, a low-gas-shift heat exchanger B12, a boiler feed water pump outlet main 13, a first automatic regulating valve 14, a process condensate booster pump 15, a second automatic regulating valve 16, a lithium bromide heat exchange unit 17, a desalted water circulation pump 18, a third automatic regulating valve 19, a fourth automatic regulating valve 20, a flow meter 21, a pressure gauge 22, a small-flow boiler feed water pump 23, a large-flow boiler feed water pump 24 with simultaneous low flow and pressure interlocking start-up, a desalted water pump 25 and other components.

[0033] The low-shift gas heat exchanger includes a low-shift gas heat exchanger A11 and a low-shift gas heat exchanger B12. The low-shift gas from the carbon dioxide reboiler passes through the low-shift gas heat exchanger A11 and the low-shift gas heat exchanger B12 in turn, and then enters the low-shift gas separator 4 from the top of the low-shift gas separator 4 after cooling. The top gas outlet pipeline of the low-shift gas separator 4 goes to the carbon dioxide absorption tower. The process condensate separated by the low-shift gas separator 4 comes out from the bottom, and after being pressurized by the process condensate pump 5, it passes through the low-shift gas heat exchanger A11 and the process condensate heat exchanger 2 in turn, and then enters the stripping tower 3 from the top of the stripping tower 3. The outlet of the process condensate pump 5 is provided with a fourth automatic regulating valve 20. The low-shift gas separator 4 is still provided with an emergency discharge valve, which forms a layered control mode with the fourth automatic regulating valve 20. Under normal circumstances, only the process condensate pump 5 and the fourth automatic regulating valve 20 at the outlet are opened to automatically control the liquid level of the low-gas separator 4. When the process condensate pump 5 jumps or other reasons cause the liquid level to be higher than the set value, the emergency discharge valve is automatically opened to discharge the process condensate into the circulating water pool to control the normal liquid level of the low-gas separator 4.

[0034] A medium-pressure steam inlet is arranged at the lower part of the stripping tower 3, and a gas outlet pipeline at the top of the stripping tower 3 goes to the conversion system. The process condensate coming out of the bottom process condensate outlet pipeline is cooled by the process condensate heat exchanger 2 and then comes out from the cold side outlet pipeline of the process condensate heat exchanger 2. The cold side outlet pipeline of the process condensate heat exchanger 2 is divided into two branches, one of which goes to the boiler feed water pump outlet main pipe 13, and a first automatic regulating valve 14 and a process condensate booster pump 15 are arranged on the branch, and the other branch goes to the circulating water tank, and a second automatic regulating valve 16 is arranged on the branch. The first automatic regulating valve 14 and the second automatic regulating valve 16 form a layered control mode. Similar to the prior art, the process condensate after stripping is provided with an online conductivity analyzer for conductivity analysis. However, the interlock output condition of the high conductivity of the process condensate is modified to automatically stop the process condensate booster pump 15 and close the first automatic regulating valve 14 when the interlock reaches the set value. The second automatic regulating valve 16 is automatically opened to a valve position opening of 30% for 3 seconds, and then automatically switched to automatically control the liquid level of the stripping tower 3.

[0035] The desalted water in the desalted water tank 7 is sent to the cold side inlet pipeline of the low-gas heat exchanger B12 through the desalted water pump 25. The hot side outlet pipeline of the low-gas heat exchanger B12 is divided into two branches, one of which is sent to the deoxidizer 10, enters from the upper part of the deoxidizer 10, flows through the packed bed layer in the tower from top to bottom, and countercurrently contacts with the low-pressure steam added from the lower part for physical deoxidation. The other branch is sent to the lithium bromide heat exchange unit 17 to recover waste heat and produce low-pressure steam. The desalted water after waste heat recovery is returned to the cold side inlet pipeline of the low-gas heat exchanger B12 through the desalted water circulation pump 18. The outlet of the desalted water circulation pump 18 is provided with a third automatic regulating valve 19. The flow rate of desalted water passing through the low-gas heat exchanger B12 is increased to automatically control the inlet temperature of the CO2 absorption tower.

[0036] The steam at the top of the deaerator 10 enters the lithium bromide heat exchange unit 17 to recover waste heat and produce low-pressure steam. The water inlet pipe of the lithium bromide heat exchange unit 17 is connected to the boiler feed water pump outlet main pipe 13. The water used to produce steam comes from the boiler feed water pump outlet main pipe 13. The fifth automatic regulating valve 1 is provided on the water inlet pipe of the lithium bromide heat exchange unit 17. Preferably, the water inlet pipe of the lithium bromide heat exchange unit 17 is provided with a liquid level high and low alarm device.

[0037] The outlet main pipe 13 of the boiler feed water pump is provided with a flow meter 21 and a pressure gauge 22, and the outlet main pipe 13 of the boiler feed water pump is connected to the outlet pipe of the deaerator 10 through the boiler feed water pump. Specifically: a small flow boiler feed water pump 23 and a large flow boiler feed water pump 24 with low flow and pressure interlocked to start standby are provided on the outlet pipe of the deaerator 10, and the outlets of the large flow boiler feed water pump 24 and the small flow boiler feed water pump 23 are connected to the outlet main pipe 13 of the boiler feed water pump. During normal operation, the process condensate booster pump 15 and the small flow boiler feed water pump 23 operate simultaneously. When the process condensate booster pump 15 and the small flow boiler feed water pump 23 cause the boiler feed water to be interrupted due to jumping or other reasons, the flow and pressure are simultaneously low and the large flow boiler feed water pump 24 is started to be interlocked to start standby. A low flow and pressure alarm device is also provided on the outlet main pipe 13 of the boiler feed water pump.

[0038] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A comprehensive recovery and utilization system for process condensate energy, comprising a stripping tower, a low-gas shift separator, a deaerator, a desalted water tank, a process condensate heat exchanger and a low-gas shift heat exchanger, characterized in that: The low-change gas heat exchanger includes a low-change gas heat exchanger A and a low-change gas heat exchanger B. The low-change gas from the carbon dioxide reboiler passes through the low-change gas heat exchanger A and the low-change gas heat exchanger B in turn for cooling and then enters the low-change gas separator from the top of the low-change gas separator. The top gas outlet pipeline of the low-change gas separator goes to the carbon dioxide absorption tower. The process condensate separated by the low-change gas separator comes out from the bottom, is pressurized by the process condensate pump, passes through the low-change gas heat exchanger A and the process condensate heat exchanger for preheating in turn, and then enters the stripping tower from the top of the stripping tower. A medium-pressure steam inlet is arranged at the lower part of the stripping tower. The top gas outlet pipeline of the stripping tower goes to the conversion system, and the process condensate coming out of the bottom process condensate outlet pipeline After being cooled by the process condensate heat exchanger, the condensate comes out from the cold side outlet pipeline of the process condensate heat exchanger. The cold side outlet pipeline of the process condensate heat exchanger is divided into two branches, one of which goes to the boiler feed water pump outlet main pipe, and is provided with a first automatic regulating valve and a process condensate booster pump, and the other goes to the circulating water tank, and is provided with a second automatic regulating valve; the first automatic regulating valve and the second automatic regulating valve form a hierarchical control mode, and the process condensate conductivity high interlock output condition is that when the interlock reaches the set value, the process condensate booster pump is automatically stopped and the first automatic regulating valve is closed, and the second automatic regulating valve is automatically opened to 30% of the valve position opening for 3 seconds, and then automatically switched to automatically control the liquid level of the stripping tower; The desalted water in the desalted water tank is pumped to the cold side inlet pipeline of the low-gas heat exchanger B. The hot side outlet pipeline of the low-gas heat exchanger B is divided into two branches, one of which is used to remove the oxygenator, and the other is used to remove the lithium bromide heat exchanger unit to recover waste heat and produce low-pressure steam. The desalted water after recovering the waste heat is returned to the cold side inlet pipeline of the low-gas heat exchanger B through the desalted water circulation pump. The top steam of the deaerator enters the lithium bromide heat exchanger unit to recover waste heat and produce low-pressure steam. The water inlet pipe of the lithium bromide heat exchanger unit is connected to the outlet main pipe of the boiler feed water pump; the outlet main pipe of the boiler feed water pump is provided with a flow meter and a pressure gauge. The outlet pipe of the deaerator is provided with a small-flow boiler feed water pump and a large-flow boiler feed water pump with low flow and pressure interlocked to start as a standby. The outlets of the large-flow boiler feed water pump with low flow and pressure interlocked to start as a standby and the small-flow boiler feed water pump are connected to the outlet main pipe of the boiler feed water pump. During normal operation, the process condensate booster pump and the small-flow boiler feed water pump operate simultaneously. When the process condensate booster pump and the small-flow boiler feed water pump are interrupted due to tripping or other reasons, the large-flow boiler feed water pump with low flow and pressure interlocked to start as a standby is started. A third automatic regulating valve is provided at the outlet of the desalted water circulation pump. The outlet of the process condensate pump is provided with a fourth automatic regulating valve; the low-gas separator is provided with an emergency discharge valve, which forms a layered control mode with the fourth automatic regulating valve. Under normal circumstances, only the fourth automatic regulating valve at the outlet of the process condensate pump is opened to automatically control the liquid level of the low-gas separator. When the process condensate pump jumps or other reasons cause the liquid level to be higher than the set value, the emergency discharge valve is automatically opened to discharge the process condensate into the circulating water pool to control the normal liquid level of the low-gas separator. The boiler feed water pump outlet main pipe is also provided with a low flow pressure alarm device; the water inlet pipe of the lithium bromide heat exchanger unit is provided with a fifth automatic regulating valve; the water inlet pipe of the lithium bromide heat exchanger unit is provided with a liquid level high and low alarm device.

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