阅读说明：本技术 一种超临界二氧化碳循环发电机组工质回收系统及控制方法 (Working medium recovery system of supercritical carbon dioxide cycle generator set and control method ) 是由 宋晓辉 李晓飞 伍刚 王涛 王阳 辛志波 赵如宇 张磊 高炜 于 2021-01-28 设计创作，主要内容包括：一种超临界二氧化碳循环发电机组工质回收系统及控制方法,包括液态储罐,来自液态储罐的CO-2工质通过低温活塞式加压泵A增压后进入蒸发器,蒸发器水侧配置有一个循环水泵；CO-2工质经过蒸发器加热气化后依次进入缓冲罐、稳压罐,稳压罐输出端接入高压储罐,高压储罐的出口跟电热油加热器相连,电热油加热器输出端通过压缩机干气密封管线连接压缩机,通过供透平机干气密封管线连接透平机,压缩机通过压缩机排气管线连接回收罐A,透平机通过透平机排气管线连接回收罐B,回收罐A和回收罐B输出端汇合后连接液态储罐。本发明能够实现S-CO-2循环发电机组在启动及运行过程中近零排放,降低了因CO-2气体排放造成的经济损失,有效防范了现场作业的安全风险。(A working medium recovery system of a supercritical carbon dioxide cycle generator set and a control method thereof comprise a liquid storage tank and CO from the liquid storage tank 2 The working medium enters the evaporator after being pressurized by the low-temperature piston type pressurizing pump A, and a circulating water pump is arranged on the water side of the evaporator; CO 2 2 The working medium is heated and gasified by the evaporator and then sequentially enters the buffer tank and the pressure stabilizing tank, the output end of the pressure stabilizing tank is connected to the high-pressure storage tank, and the outlet of the high-pressure storage tank is connected with the electric heating oil heaterThe electric heating oil heater output end is connected with the compressor through a compressor dry gas sealing pipeline, the electric heating oil heater output end is connected with the compressor through a turbine dry gas sealing pipeline, the compressor is connected with the recovery tank A through a compressor exhaust pipeline, the turbine is connected with the recovery tank B through a turbine exhaust pipeline, and the recovery tank A and the recovery tank B output end are connected with the liquid storage tank after being converged. The invention can realize S-CO 2 The zero emission of the circulating generator set in the starting and running processes is reduced, and the CO content is reduced 2 Economic loss caused by gas emission effectively prevents the safety risk of field operation.)

1. The working medium recovery system of the supercritical carbon dioxide cycle generator set is characterized by comprising a liquid storage tank (1), wherein CO in the liquid storage tank (1) is recycled₂The working medium enters an evaporator (3) after being pressurized by a low-temperature piston type pressurizing pump A (2), and a circulating water pump (4) is arranged on the water side of the evaporator (3); the CO is₂Working medium gets into buffer tank (5), surge tank (6) in proper order after evaporimeter (3) heating gasification, draw a branch road in surge tank (6) and insert high-pressure storage tank (7), the export of high-pressure storage tank (7) links to each other with electric oil heater (H), compressor (8) are connected through compressor dry gas seal pipeline (I) to electric oil heater (H) output, through supplying turbine dry gas seal pipeline (II) to connect turbine (9), recovery tank A (10) are connected through compressor exhaust pipe line (III) in compressor (8), recovery tank B (11) are connected through turbine exhaust pipe line (IV) in turbine (9), recovery tank A (10) and recovery tank B (11) output join the back and connect liquid storage tank (1).

2. The working medium recovery system of the supercritical carbon dioxide cycle generator set according to claim 1, wherein the cylinder exhaust, pipeline exhaust and dry gas sealing leakage of the compressor (8) are collected to a compressor exhaust line (III).

3. The working medium recovery system of the supercritical carbon dioxide cycle generator set according to claim 1, characterized in that the carbon ring protection gas, cylinder exhaust gas and dry gas sealing leakage gas of the turbine (9) are collected to a turbine exhaust line (IV).

4. The working medium recovery system of the supercritical carbon dioxide cycle generator set according to claim 1, wherein an input end of a turbine exhaust line (IV) is connected with an exhaust line (V), the exhaust line (V) is provided with a pneumatic shutoff valve (31) and a check valve (27), and the exhaust line (V) is communicated with a system emptying pipeline for air supply and maintenance and exhaust of each storage tank.

5. The working medium recovery system of the supercritical carbon dioxide cycle generator set according to claim 1, wherein the recovery tank A (10) and the recovery tank B (11) have the same structure, and the recovery tank A (10) is provided with a vacuum pumping pump (16) and a matched inlet shutoff valve (32) for vacuumizing the tank body before the working medium is recovered; the recycling tank A (10) is provided with a working medium compression device and a compression motor (20), the side surface of the recycling tank A (10) is provided with a working medium cooling device (18), the recycling tank A (10) is provided with a sewage disposal pool (14), and a switch is controlled through a bottom sewage disposal valve (34).

6. The working medium recovery system of the supercritical carbon dioxide cycle generator set according to claim 1, wherein a check valve (22) and a regulating valve (28) are sequentially arranged on the recovery tank A (10) and the working medium recovery inlet pipeline, and are used for controlling gas parameters entering the recovery tank A (10).

7. The working medium recovery system of the supercritical carbon dioxide cycle generator set according to claim 1, wherein the bottom of the recovery tank A (10) is connected with a delivery pump B (42), and the pressurized and liquefied working medium is delivered to the liquid storage tank (1) again through a check valve (24) and a regulating valve (30).

8. The working medium recovery system of the supercritical carbon dioxide cycle generator set according to claim 7, wherein a pipeline is arranged in parallel at the outlet of the delivery pump B (42) and is directly connected to the inlet of the evaporator (3) through the regulating valve (36) and the check valve (26), and when the gas pressure and temperature in the recovery tank A10 meet the gas inlet requirements of the evaporator, the gas is directly fed into the recovery tank A and does not enter the liquid storage tank (1).

9. A control method of a working medium recovery system of a supercritical carbon dioxide cycle generator set is characterized by comprising the following steps:

working medium recovery control on the exhaust side of the compressor (8):

the recovery of working medium at the exhaust side of the compressor (8) is mainly carried out at the initial starting stage and after the compressor (8) is shut down, and CO in the high-pressure storage tank (7) is required to be recovered at the initial starting stage of the compressor (8)₂The working medium is introduced into an electric heating oil heater (H) for heating, and the heated CO₂The working medium enters a dry gas sealing disc station of the compressor from an air supply line (I) to supply a large amount of unheated cold CO existing in the air supply line (I)₂The working medium is introduced into a compressor (8), is discharged through a compressor cylinder body exhaust valve (39) and an outlet pipeline vent valve (38), and the discharged gas is collected to a compressor exhaust pipeline (III) and enters a recovery tank A (10) through a check valve (22) and a regulating valve (28);

after the compressor (8) is shut down, according to the normal shutdown protection logic, the vent valve (38) of the outlet pipeline of the compressor is opened in an interlocking way, and a large amount of high-temperature and high-pressure CO is generated₂The working medium enters an exhaust pipeline (III) and finally enters a recovery tank A (10);

working medium recovery control on the exhaust side of the turbine (9):

the working medium recovery of the exhaust side of the turbine (9) is also carried out at the initial stage of starting and after stopping the turbine, and CO in the high-pressure storage tank (7) is recovered₂Working medium guideHeating by electric hot oil heater (H), and heating to obtain heated CO₂The working medium enters a dry gas sealing disc station of the turbine from the gas supply line (II) to supply a large amount of unheated low-temperature CO in the gas supply line (II)₂The working medium is introduced into a turbine (9), and is discharged through a turbine carbonization protection discharge valve (40) and a cylinder body emptying valve (41), and the discharged gas is gathered to a turbine exhaust pipeline (IV) and enters a recovery tank B (11) through a check valve (23) and a regulating valve (29);

gas coming from a system emptying pipeline and maintenance exhaust gas from each storage tank are gathered to an exhaust emptying pipeline (V), and are controlled by a pneumatic valve (31) and a check valve (27), so that the gas can enter a pressure stabilizing tank A or a pressure stabilizing tank B, and the gas is selectively discharged according to the actual condition of the system;

control of recovery tank a (10):

before the recovery tank A (10) recovers working media, the pneumatic valve (32) is firstly opened, the vacuum pump (16) is started, the recovery tank A (10) is vacuumized, and when a pressure gauge P in the recovery tank A (10) is used_aWhen the pressure is displayed above-80 kPa, the representation of the completion of the vacuumizing is carried out, the pneumatic valve (32) is automatically closed, the vacuum pump (16) is stopped in an interlocking way, the vacuumizing of the recovery tank A (10) is completed, the air inlet regulating valve of the recovery tank A (10) is opened at the moment, the gas in the exhaust pipeline (III) is introduced into the recovery tank A (10), and the pressure P in the tank body is monitored in real time_aWhen P is_aAfter the pressure reaches 4.5MPa, a compression motor (20) of the recovery tank A (10) is started to compress the recovered working medium, the recovered working medium is simultaneously put into a cooling device (18) of the recovery tank A (10) to cool the compressed working medium to below 8 ℃, a temperature sensor monitors the temperature of the working medium in real time, the working medium becomes liquid after being compressed and cooled, at the moment, a delivery pump B (42) is started to liquefy CO₂The working medium is conveyed to the liquid storage tank (1) to complete the recovery of the whole working medium;

before the first start-up of the recovery tank A (10), the introduced CO is utilized₂The working medium purges recovery tank A (10), and purges to blowdown pond A (14) through pneumatic valve (34), and recovery tank bottom is every 8 hours open the blow-off valve 1min and is carried out hydrophobic gas dredging in bottom, when liquid storage tank (1) breaks down or the pressure of delivery pump B (42) export and liquid storage tank (1) pressure mismatch, will retrieve tank A (10) through governing valve (36)The liquid working medium in the evaporator (3) is directly sent to the evaporator;

the control of the recovery tank B (11) is similar to the control method of the recovery tank A (10), the compressor emptying pipeline (III) and the turbine emptying pipeline (IV) are combined together by opening the shut-off valve (37) and are respectively sent into different recovery tanks according to actual requirements, and when one of the recovery tanks is in fault in actual use, air inlet is cut off through the inlet adjusting valve, and the other recovery tank is started to recover working media.

10. The control method of the working medium recovery system of the supercritical carbon dioxide cycle generator set according to claim 9, characterized in that a pneumatic shut-off valve (37) is arranged between the compressor exhaust gas blow-down line (III) and the turbine exhaust gas blow-down line (IV), and the valve is a normally closed valve for isolating the exhaust gas of the lines.

Technical Field

The invention relates to the technical field of supercritical carbon dioxide circulating generator sets, in particular to a working medium recovery system of a supercritical carbon dioxide circulating generator set and a control method.

Background

Supercritical carbon dioxide (S-CO for short)₂) The cycle is proposed in 50-60 years in the 20 th century. In the last 10 years, large manpower and material resources are invested in research on S-CO in many countries₂And circulating to make the method become an industrial hotspot. The development trend is related to the efficient and flexible utilization of various energy sources and the reduction of environmental pollution of human beings on one hand, and on the other hand, the Rankine cycle development mainly taking water vapor as a working medium is limited by factors such as metal materials and the like to enter a bottleneck period, and CO is generated₂The non-toxic, colorless and tasteless non-flammable working medium which is extremely easy to obtain in the nature is favored.

Different from the conventional thermal power generating unit, S-CO₂The circulating generator set is provided with CO₂The series of equipment comprises a liquefied storage tank, a booster pump, an evaporator, a buffer tank, a pressure stabilizing tank, a high-pressure storage tank and accessory equipment of working media, wherein the whole CO is formed by the equipment₂Storage of a working mediumA charging, discharging and monitoring system is S-CO₂The circulating generator set provides stable and reliable CO which meets the parameters required by the process system₂Working medium. But existing about S-CO₂Little CO is visible in the literature for cycle power plants₂Working medium recovery unit.

S-CO₂The core equipment of the circulating generator set comprises a main compressor, a high-low pressure turbine and auxiliary equipment thereof. Different from the conventional thermal power generating unit, the main compressor adopts CO for sealing the shaft end₂The gas is used as sealing gas, and the shaft end seal of the high-low pressure turbine also adopts CO₂The gas is used as sealing gas, similar to steam of a steam turbine shaft seal of a thermal power generating unit. Before the compressor or turbine is started, the CO with specific temperature and pressure needs to be charged firstly₂The gas is referred to as dry seal gas. In order to quickly meet the temperature of dry gas seal gas in the initial stage of starting, besides the dry gas seal electric heating oil heating device, in the actual operation, the temperature of the dry gas seal gas needs to be raised by discharging a large amount of dry gas seal gas through a compressor cylinder body and a pipeline, so that a large amount of CO is generated₂The gas is wasted. In addition, when filled with CO₂When various storage tanks of gas are overhauled or the pressure of a system exceeds the limit, a large amount of CO is required₂And the waste of system working media is aggravated by discharging. Large amount of CO₂The discharge of gas directly causes objective economic loss on one hand and CO on the other hand₂The accumulation of gases in small spaces poses a great safety risk and also causes greenhouse gas pollution of the environment.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide a working medium recovery system of a supercritical carbon dioxide cycle generator set and a control method thereof₂On the basis of storage, charging and discharging and monitoring of working medium, CO is integrated₂The working medium recovery system forms a complete flow. New CO₂The working medium recovery system comprises different functional units such as collection, pressurization, cooling liquefaction, pollution discharge, conveying and the like, and can realize S-CO₂The zero emission of the circulating generator set in the starting and running processes is reduced, and the CO content is reduced remarkably₂Economic loss caused by gas emission and effective prevention ofSafety risks for field operations.

In order to achieve the purpose, the invention adopts the technical scheme that:

a working medium recovery system of a supercritical carbon dioxide cycle generator set comprises a liquid storage tank 1, wherein CO from the liquid storage tank 1₂The working medium enters the evaporator 3 after being pressurized by a low-temperature piston type booster pump A2, and a circulating water pump 4 is arranged on the water side of the evaporator 3; the CO is₂Working medium gets into buffer tank 5, surge tank 6 in proper order after 3 heats gasifications through the evaporimeter, draw forth a branch road in the surge tank 6 and insert high-pressure storage tank 7, high-pressure storage tank 7 export links to each other with electric oil heater H, electric oil heater H output passes through compressor dry gas seal pipeline I and connects compressor 8, connects turbine 9 through supplying turbine dry gas seal pipeline II, compressor 8 passes through compressor exhaust pipe III and connects recovery tank A10, turbine 9 passes through turbine exhaust pipe IV and connects recovery tank B11, recovery tank A10 and recovery tank B11 output join the back and connect liquid storage tank 1.

And the cylinder body exhaust, pipeline exhaust and dry gas sealing leakage of the compressor 8 are collected to a compressor exhaust pipeline III.

The carbon ring protection gas, cylinder body exhaust and dry gas sealing leakage gas of the turbine 9 are collected to a turbine exhaust pipeline IV.

The input end of a turbine exhaust pipeline IV is connected with an exhaust pipeline V, a pneumatic shutoff valve 31 and a check valve 27 are arranged on the exhaust pipeline V, and the exhaust pipeline V is communicated with a system emptying pipeline for air supply and maintenance and exhaust of each storage tank.

A normally closed pneumatic valve 37 for isolation is provided between the exhaust line III and the exhaust line IV.

The recovery tank A10 and the recovery tank B11 have the same structure, and the recovery tank A10 is provided with a vacuum pump 16 and a matched inlet shutoff valve 32 for vacuumizing the tank body before working medium recovery; the recycling tank A10 is provided with a working medium compression device and a compression motor 20, the side surface of the recycling tank A is provided with a working medium cooling device 18, the recycling tank A10 is provided with a sewage disposal pool 14, and the switch is controlled by a bottom sewage disposal valve 34.

The recovery tank A10 and the working medium recovery inlet pipeline are sequentially provided with a check valve 22 and a regulating valve 28 for controlling the gas parameters entering the recovery tank A.

The bottom of the recovery tank A10 is connected with a delivery pump B42, and the pressurized and liquefied working medium is delivered to the liquid storage tank 1 again through the check valve 24 and the regulating valve 30.

The outlet of the delivery pump B42 is provided with a pipeline in parallel, the pipeline is directly connected to the inlet of the evaporator 3 through the regulating valve 36 and the check valve 26, and when the gas pressure and the temperature in the recovery tank A10 meet the gas inlet requirement of the evaporator, the gas is directly sent into the liquid storage tank 1 and does not enter the liquid storage tank.

A control method of a working medium recovery system of a supercritical carbon dioxide cycle generator set comprises the following steps:

working medium recovery control on the exhaust side of the compressor 8:

the recovery of working medium at the exhaust side of the compressor 8 is mainly carried out at the initial starting stage and after the shutdown of the compressor 8, and CO in the high-pressure storage tank 7 is required to be recovered at the initial starting stage of the compressor 8₂The working medium is introduced into an electric heating oil heater H for heating, and the heated CO₂The working medium enters the dry gas sealing disc station of the compressor from the gas supply line I to supply a large amount of cold CO which cannot be heated in the gas supply line I₂The working medium is introduced into the compressor 8, is discharged through a compressor cylinder body exhaust valve 39 and an outlet pipeline vent valve 38, and the discharged gas is gathered to a compressor exhaust pipeline III and enters a recovery tank A through a check valve 22 and an adjusting valve 28;

after the compressor 8 is stopped, the emptying valve 38 of the outlet pipeline of the compressor is interlocked and opened according to the normal shutdown protection logic, and a large amount of high-temperature and high-pressure CO is discharged₂The working medium enters an exhaust pipeline III and finally enters a recovery tank A10;

working medium recovery control at the exhaust side of the turbine 9:

the working medium recovery at the exhaust side of the turbine 9 is also carried out at the initial starting stage and after the shutdown of the turbine, and CO in the high-pressure storage tank 7 is recovered₂The working medium is introduced into an electrothermal oil heater H for heating, and the heated CO₂The working medium enters the dry gas sealing disc station of the turbine from the gas supply line II to ensure that the gas in the gas supply line II is largeLow temperature CO of non-heatable amount₂The working medium is introduced into a turbine 9, discharged through a turbine carbonization protection discharge valve 40 and a cylinder body emptying valve 41, and the discharged gas is gathered to a turbine exhaust line IV and enters a recovery tank B11 through a check valve 23 and a regulating valve 29;

the gas coming from the system emptying pipeline and the maintenance exhaust gas coming from each storage tank are gathered to an exhaust emptying pipeline V, and are controlled by a pneumatic valve 31 and a check valve 27, so that the gas can enter a pressure stabilizing tank A or a pressure stabilizing tank B, and the gas is selectively discharged according to the actual condition of the system;

control of recovery tank a 10:

before the recovery tank A10 is used for recovering working medium, the pneumatic valve 32 is firstly opened, the vacuum pump 16 is started, the recovery tank A10 is vacuumized, and when the pressure gauge P is in the recovery tank A10_aWhen the pressure is higher than-80 kPa, the representation of the completion of the vacuum pumping is carried out, the pneumatic valve 32 is automatically closed, the vacuum pump 16 is stopped in an interlocking manner, the vacuum pumping of the recovery tank A10 is completed, the air inlet regulating valve of the recovery tank A10 is opened at the moment, the gas in the exhaust pipeline III is introduced into the recovery tank A10, and the pressure P in the tank body is monitored in real time_aWhen P is_aAfter the pressure reaches 4.5MPa, a compression motor 20 of the recovery tank A10 is started to compress the recovered working medium, and simultaneously a cooling device 18 of the recovery tank A10 is put into the compression motor to cool the compressed working medium to 8 ℃ (4.5MPa of CO₂The corresponding liquid phase point is below 9.9 ℃), the temperature sensor monitors the temperature of the working medium in real time, the working medium becomes liquid after being compressed and cooled, at the moment, the delivery pump B42 is started, and liquefied CO is delivered₂The working medium is conveyed to the liquid storage tank 1 to complete the recovery of the whole working medium;

before the first start-up of the recovery tank A10, the CO introduced is utilized₂The working medium purges the recovery tank A10, purges the recovery tank A14 through a pneumatic valve 34, opens a drain valve at the bottom of the recovery tank every 8 hours for 1min to drain water and degas the gas at the bottom, and when the liquid storage tank 1 breaks down or the pressure at the outlet of a delivery pump B42 is not matched with the pressure of the liquid storage tank 1, directly sends the liquid working medium in the recovery tank A10 to the evaporator 3 through a regulating valve 36;

the control of the recovery tank B11 is similar to the control method of the recovery tank A10, the compressor emptying pipeline III and the turbine emptying pipeline IV are combined together by opening the shutoff valve 37 and are respectively sent into different recovery tanks according to actual requirements, when one of the recovery tanks is in fault in actual use, air inlet is cut off through the inlet regulating valve, and the other recovery tank is started to recover working media.

And a pneumatic shutoff valve 37 is arranged between the compressor exhaust and emptying pipeline III and the turbine exhaust and emptying pipeline IV, and is a normally closed valve for isolating exhaust of the pipelines.

The invention has the beneficial effects that:

1) in the conventional S-CO₂On the basis of working medium storage, charging and discharging and monitoring of the circulating power generation system, CO is integrated₂The working medium recovery system forms the whole complete process.

2)CO₂The working medium recovery system comprises different functional units such as collection, pressurization, cooling liquefaction, pollution discharge and transportation, and can realize S-CO₂The zero emission of the circulating generator set in the starting and running processes is reduced, and the CO content is reduced remarkably₂Economic loss caused by gas emission effectively prevents the safety risk of field operation and reduces the pollution of greenhouse gas.

3) The recovery system is provided with two parallel recovery tanks, so that the quantity of recovered working medium is increased, and the recovery system is more flexible in use. The method has the characteristics of fault removal, interactive commissioning, real-time monitoring of operation parameters and the like.

4) The vacuum pump arranged in the recovery tank can pump the tank body to vacuum above-80 kPa before the working medium is recovered, when the vacuum reaches a set value, the vacuum pump is interlocked and stopped, and the inlet pneumatic valve is interlocked and closed, so that the purity of the recovered carbon dioxide is ensured.

5) The recovery tank is provided with a bottom pollution discharge pool, so that the recovery tank can be used for purging the tank body during first recovery, and can be matched with the tank body at any time for pressure relief and drainage and ventilation in the use process.

6) Automatic pollution discharge: and opening a discharge valve at the bottom of the recovery tank every 8 hours for 1min to drain and ventilate the bottom.

7) And (5) starting compression and cooling after the purity in the recovery tank is monitored to be qualified, and preferentially discharging when the purity is unqualified.

8) The temperature, pressure and purity monitoring device arranged on the recovery tank can realize real-time display in the whole recovery process and can be used as a basis for equipment control.

Drawings

FIG. 1 is a schematic flow chart of the present invention.

In the figure: 1. a liquid storage tank; 2 a pressure pump; 3. an evaporator; 4. a water pump; 5. a buffer tank; 6. a surge tank; 7. a high pressure storage tank; 8. a compressor; 9. a turbine; 10. a recovery tank A; 11. a recovery tank B; 12. a cryogenic transfer pump B; 13. a cryogenic transfer pump C; 14. 15 a sewage disposal pool; 16. 17 a vacuum pump for recovering the tank; 18. 19 a cooling device; 20. 21 a recovery tank compression motor; 22. 23, 24, 25, 26, 27 check valves; 28. 29, 30, 36 regulating valves; 31. 32, 33, 34, 35 and 37 are pneumatic shutoff valves; 38. an air release valve of an outlet pipeline of the compressor; 39 compressor cylinder discharge valve; 40. a turbine carbon ring protection discharge valve; 41. a turbine cylinder block discharge valve; 42. an inlet manual valve of the delivery pump B; 43. inlet hand valve of transfer pump C.

I, a high-pressure storage tank is used for sealing an air supply line for dry gas of a compressor; II, a high-pressure storage tank is used for sealing an air supply line for dry gas of the turbine; III is a dry gas sealing exhaust pipeline of the compressor; IV is a dry gas sealing exhaust pipeline of the turbine; v is a system emptying pipeline and a pipeline formed by maintenance and exhaust of each storage tank; h is an electric oil heater. P_aIs a pressure measuring point T of working medium in a pressure stabilizing tank A_aIs a temperature measuring point S of the working medium in the pressure stabilizing tank A_aIs a measure point for the purity of the working medium in surge tank A, P_bIs a pressure measuring point T of working medium in a pressure stabilizing tank B_bIs a temperature measuring point of working medium in a pressure stabilizing tank B, S_bIs a measure point for the purity of the working medium in surge tank B, P₁Is the pressure of the liquid tank, P₂Is the evaporator inlet pressure.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As shown in FIG. 1, in a conventional S-CO₂CO from a liquid tank 1 in a cycle power plant₂The working medium enters the evaporator 3 after being pressurized by the low-temperature piston type booster pump A, the working medium is heated and gasified by a water bath type electric heater in the evaporator 3, and a circulating water pump 4 is arranged on the water side of the evaporator 3; CO after heating and gasification₂The working medium enters a buffer tank 5 and a pressure stabilizing tank 6 in sequence, and the pressure stabilizing tank 6 is used as S-CO₂And circulating an air inlet circulating unit of the generator set, wherein stable air inlet pressure needs to be maintained. A branch is led out from the pressure stabilizing tank 6 and connected into a high-pressure storage tank 7, the high-pressure storage tank 7 is connected with an electric heating oil heater H, and the temperature of gas entering a compressor and a turbine for sealing dry gas can be set through the H. When the unit is started and stopped, the gas in the high-pressure storage tank 7 is heated to a set temperature by the electric heating oil heater H, then is respectively supplied to the compressor 8 and the turbine 9 through the dry gas sealing pipeline I and the dry gas sealing pipeline II of the turbine, and the dry gas sealing gas entering the compressor 8 is partially discharged through the leakage pipeline, and the other part is directly discharged from the exhaust of the cylinder body of the compressor 8 and the outlet pipeline in order to meet the temperature requirement of the gas entering the compressor and is directly discharged to the atmosphere. Similarly into the turbine 9. In addition, in the operation of the unit, the incoming air from the system emptying pipeline and the exhaust air from the maintenance of each storage tank are also directly exhausted to the atmosphere.

In the invention, a vent pipeline III of a compressor 8, a vent pipeline IV of a turbine, incoming gas from a system vent pipeline and a maintenance exhaust main pipeline V from each storage tank are combined together to form a total vent pipeline which is respectively led into a recovery tank A10 and a recovery tank B11. The recovered working medium is pressurized, cooled and liquefied in the recovery tank A/B, then is recovered by the delivery pump 12/13, the check valve 24/25 and the regulating valve 30 and enters the liquid storage tank 1, and the other part of the working medium enters the inlet of the evaporator through the regulating valve 36 and the check valve 26, so that the recovery of the whole working medium is completed.

Taking the recycling tank A10 as an example, the complete recycling device comprises a vacuum pump 16, a control valve 32, a tank compressor 20, a blowdown tank 14 and a controlValve 34, recovery tank cooling device 18, delivery pump B for backflow of pressurized liquefied working medium, and temperature measuring point T for monitoring parameters of recovery tank in real time_aPressure measuring point P_aAnd purity measuring point S_aA check valve 22 for controlling the recycling of working medium and an inlet regulating valve 28.

The recovery tank B has the same structure.

And the cylinder body exhaust (controlled by the pneumatic valve 39), the outlet pipeline exhaust (controlled by the pneumatic valve 38) and the dry gas sealing leakage gas of the compressor 8 are collected to a compressor exhaust pipeline III.

The carbon ring protection gas (controlled by the pneumatic valve 40), the cylinder exhaust (controlled by the pneumatic valve 41) and the dry gas sealing leakage of the turbine 9 are collected to a turbine exhaust pipeline IV.

The system is characterized in that gas is supplied from a system emptying pipeline, and the maintenance and exhaust gas of each storage tank is collected to an exhaust pipeline V.

A normally closed isolation valve 37 is provided between the exhaust line III and the exhaust line IV for isolation.

The exhaust line V merges into the exhaust line IV via a pneumatic shut-off valve 31 and a non-return valve 27.

The recovery tank A is provided with a vacuum pump 16 and a matched inlet shutoff valve 32 and is used for vacuumizing the tank body before the working medium is recovered.

The recovery tank A is provided with a working medium compression device and a compression motor 20, and compression is started when the pressure of the tank body reaches a certain static pressure.

The recovery tank A is provided with a working medium cooling device 18, and the temperature can be reduced in the working medium compression process, so that the working medium can be compressed, cooled and liquefied.

The recovery tank a is provided with a blowdown sump 14 which is switched by a bottom blowdown valve 34 to effect system blowdown prior to pressurization of the recovery tank.

The bottom of the recovery tank A is connected with a delivery pump B, and the pressurized and liquefied working medium is delivered into the liquid storage tank 1 again through the check valve 24 and the regulating valve 30.

The outlet of the delivery pump B is provided with a pipeline in parallel, the pipeline is directly connected to the inlet of the evaporator 3 through the regulating valve 36 and the check valve 26, and when the gas pressure and the temperature in the recovery tank A meet the gas inlet requirement of the evaporator 3, the gas is directly sent into the evaporator 3 and does not enter the liquid storage tank 1.

The recovery tank A and the working medium recovery inlet pipeline are sequentially provided with a check valve 22 and a regulating valve 28 for controlling the gas parameters entering the recovery tank A.

The affiliated recovery tank A is provided with a pressure measuring point P for monitoring the parameters of the recovered working medium_aTemperature measuring point T_aPurity measuring point S_aLiquid tank station P for control₁Evaporator inlet measuring point P₂。

The control method and the system configuration of the recovery tank B and the recovery tank A are consistent, and the protection range is also consistent.

(1) Recovery control of dry gas seal gas entering the compressor 8:

low temperature CO from high pressure storage tank 7₂The working medium is firstly sent to an electric heating oil heater H, and the temperature of gas at the outlet of the heater is set to be 85-95 ℃. To increase low temperature CO₂And (3) introducing gas at the outlet of the heater H into a chamber of the compressor through a dry gas sealing gas supply line I, simultaneously opening a gas exhaust valve 39 of a cylinder body of the compressor and a discharge valve 38 of an outlet pipeline of the compressor, completely discharging the gas introduced into the compressor 8 into a gas exhaust line III, and finally entering a recovery tank A through a check valve 22 and an adjusting valve 28.

(2) And (3) recovery control of dry gas seal gas entering the turbine 9:

low temperature CO from high pressure storage tank 7₂And (4) delivering the working medium to an electric heating oil heater H, and setting the temperature of gas at the outlet of the heater to be 120-135 ℃. It should be noted that the compressor dry seal gas and the turbine dry seal gas are not put into operation at the same time, and therefore the temperatures of the outlet gases can be set separately. To increase low temperature CO₂The temperature of the working medium and the existing gas in the discharge pipeline are introduced into the cavity of the turbine through the dry gas sealing gas supply pipeline II, the carbon ring protection exhaust valve 40 and the cylinder body discharge valve 41 of the turbine are opened at the same time, the gas introduced into the turbine 9 is completely discharged into the exhaust pipeline IV, and finally enters the recovery tank B through the check valve 23 and the regulating valve 29In (1).

(3) Recovery control of the exhaust line V:

when the unit is shut down and filter screen replacement or equipment maintenance (including maintenance of each storage tank) is carried out, all working media in the system need to be emptied. Firstly, system air input and maintenance air exhaust of each storage tank are led into an exhaust pipeline V, and are merged into the front of an inlet check valve 23 of a recovery tank B through a pneumatic shutoff valve 31 and a check valve 27, and the air input and maintenance air input are controlled by an inlet adjusting valve 29 of the recovery tank B to enter the recovery tank B. When the recovery tank B is abnormal and can not be recovered, the closing valve 37 is opened, the gas in the exhaust pipeline V is merged into the exhaust pipeline III, and finally the gas is recovered to the recovery tank A.

(4) Control of the vacuum pump 16 in the recovery tank a:

before the working medium is recovered, the inlet regulating valve 28 is closed, the tank blowdown valve 34 is closed, the inlet manual valve 42 of the delivery pump B is closed, the vacuum pump inlet shutoff valve 32 is opened, and the vacuum pump 16 is started. Closely monitoring the pressure P of the recovery tank A after the vacuum pump is started normally_aWhen P is_a<At-80 kPa, the interlock closes the vacuum pump inlet shutoff valve 32, shutting down the vacuum pump 16.

(5) Control of the compressor motor 20 in recovery tank a:

when the recovery tank A is evacuated to a vacuum level of-80 kPa or higher, the vacuum pump 16 is stopped and the shut-off valve 32 is closed. The manual valve 42 at the inlet of the delivery pump B is kept closed, the blowdown valve 34 is kept closed, the pressure of the regulating valve 28 at the inlet of the recovery tank A is set to be automatic, and the pressure point P of the tank body is tracked_aThe pressure set value was set at 4.5 MPa. When P is present_aWhen the pressure reaches 4.5MPa, the motor 20 of the compression device is started to compress the working medium recovered in the recovery tank A. After the compressor motor 20 is started, the cooling device 18 is started in an interlocking manner, and finally the working medium recovered in the recovery tank is compressed, cooled and liquefied. When the pressure of the working medium in the recovery tank A is compressed to P_a＞P₁At +0.5, the compressor motor 20 is stopped.

(6) Controlling a drain valve of the recovery tank A:

before the recovery tank is started for the first time, the introduced CO is utilized₂The working medium purges the recovery tank and purges the recovery tank into a sewage disposal pool A through a pneumatic valve 34, and the discharge valve 34 also has an emergency dischargeThe tank body has the functions of draining water and dredging air. In order to prevent the recycled circulating working medium from containing impurities such as water vapor, the automatic blowdown function of the recycling tank is added, namely the discharge valve 34 is opened at the bottom of the recycling tank every 8 hours, and the bottom is kept for 1min for drainage and ventilation.

(7) And (3) controlling a delivery pump B matched with the recovery tank A:

when the pressure P of the working medium in the recovery tank A is_a＞P₁+0.5, the compressor motor 20 is off. Opening a manual valve 42 at the inlet of the delivery pump B, opening an inlet regulating valve 30 of the liquid storage tank 1, keeping the opening degree of 10-50%, manually regulating, starting the delivery pump at the moment, and recovering the liquid CO in the tank₂The working medium is recycled to the storage tank 1.

When the liquid storage tank 1 is in failure or the pressure is not matched, and P_a＞P₂And when the pressure is +0.5, the recovered working medium at the outlet of the delivery pump B can be directly sent to the inlet of the evaporator through the regulating valve 36 and the check valve 26.

(8) The control of the recovery tank B and the supporting equipment is similar to that of the recovery tank A in the above-mentioned (4) to (6).