阅读说明：本技术 一种间接油气冷凝回收装置及其回收工艺 (Indirect oil gas condensation recovery device and recovery process thereof ) 是由 陈叶青 陈经 邱鸿 吕林梅 郭利平 赵强 朱新华 于 2020-06-11 设计创作，主要内容包括：本发明介绍了一种间接油气冷凝回收装置及其回收工艺,回收装置包括：油气输送系统、载冷系统和低温制冷系统；所述的油气输送系统包括预冷器、浅冷器和深冷器；所述的载冷系统包括第一载冷循环回路、第二载冷循环回路和第三载冷循环回路；所述的低温制冷系统包括压缩机、油气分离器、冷凝器气液分离器、板式换热器、膨胀阀、蒸发器等；该间接油气冷凝回收装置的回收工艺利用一个制冷系统完成整个油气冷凝阶段的温度控制,油气冷凝过程依次经历预冷阶段、浅冷阶段和深冷阶段,利用深冷阶段的载冷剂和出口低温油气通过换热获得冷量,油气冷量得到效回收利用,减少制冷系统的整体能量消耗,减少企业的运行成本。(The invention introduces an indirect oil gas condensation recovery device and a recovery process thereof, wherein the recovery device comprises: the system comprises an oil gas conveying system, a cold carrying system and a low-temperature refrigerating system; the oil-gas conveying system comprises a precooler, a shallow cooler and a deep cooler; the cold carrying system comprises a first cold carrying circulation loop, a second cold carrying circulation loop and a third cold carrying circulation loop; the low-temperature refrigeration system comprises a compressor, an oil-gas separator, a condenser gas-liquid separator, a plate heat exchanger, an expansion valve, an evaporator and the like; according to the recovery process of the indirect oil gas condensation recovery device, a refrigeration system is utilized to complete temperature control of the whole oil gas condensation stage, the oil gas condensation process sequentially passes through the precooling stage, the shallow cooling stage and the copious cooling stage, cold energy is obtained by utilizing secondary refrigerant and outlet low-temperature oil gas in the copious cooling stage through heat exchange, oil gas cold energy is effectively recycled, the overall energy consumption of the refrigeration system is reduced, and the operation cost of enterprises is reduced.)

1. The utility model provides an indirect oil gas condensation recovery unit, includes oil gas conveying system, carries cold system and cryogenic refrigeration system, characterized by: the oil and gas delivery system comprises a deep cooler (16), a shallow cooler (23) and a precooler (28); the low-temperature oil-gas outlets of the deep cooler (16), the shallow cooler (23) and the precooler (28) are respectively provided with a first oil-gas temperature sensor (29), a second oil-gas temperature sensor (31) and a third oil-gas temperature sensor (33), the oil-gas inlets are respectively provided with a first oil-gas inlet temperature sensor (30), a second oil-gas inlet temperature sensor (32) and a third oil-gas inlet temperature sensor (34), and the bottoms of the deep cooler (16), the shallow cooler (23) and the precooler (28) are respectively provided with a condensed oil discharge port; a fan (35) is arranged on an oil-gas inlet pipeline of the precooler (28), and an oil-gas outlet of the precooler (28) is communicated with an oil-gas inlet of the shallow cooler (23); the oil-gas outlet of the shallow cooler (23) is communicated with the oil-gas inlet of the deep cooler (16); an oil gas outlet of the chiller (16) is communicated with the second plate heat exchanger (19);

the cold-carrying system comprises a first cold-carrying circulation loop, a second cold-carrying circulation loop and a third cold-carrying circulation loop which are respectively connected with cold-carrying agent inlets and cold-carrying agent outlets of the deep cooler (16), the shallow cooler (23) and the precooler (28); the first cold-carrying circulation loop consists of a first liquid storage tank (11), a hydraulic pump (12), a first bypass electromagnetic valve (13), a first electromagnetic valve (14), a first cold-carrying temperature sensor (15) and an expansion tank (17); the second cold-carrying circulating loop consists of a second liquid storage tank (18), a second plate type heat exchanger (19), a second bypass electromagnetic valve (20), a second electromagnetic valve (21) and a second cold-carrying temperature sensor (22); the third cold-carrying circulation loop consists of a third liquid storage tank (24), a third plate heat exchanger (25), a third cold-carrying temperature sensor (26) and a third electromagnetic valve (27); the first cold-carrying temperature sensor (15) is arranged at a cold-carrying agent inlet of the chiller (28), one end of the first bypass electromagnetic valve (13) is connected with the first cold-carrying temperature sensor (15) at the cold-carrying agent inlet of the chiller (28), the other end of the first bypass electromagnetic valve is connected with the second cold-carrying temperature sensor (22) in the second cold-carrying circulation loop, the first electromagnetic valve (14) is communicated with the cold-carrying agent inlet and outlet of the chiller (28), and the first liquid storage tank (11), the hydraulic pump (12) and the expansion tank (17) are connected on a pipeline of the first cold-carrying circulation loop in series; the second cold carrying temperature sensor (22) is arranged at a cold carrying agent inlet of the shallow cooler (23), one end of a second bypass electromagnetic valve (20) is connected with an inlet of a second plate type heat exchanger (19) in a second cold carrying circulation loop, the other end of the second bypass electromagnetic valve is connected with a third cold carrying temperature sensor (26) in a third cold carrying circulation loop, the second electromagnetic valve (21) is communicated with a cold carrying agent inlet and an outlet of the shallow cooler (23), and the second liquid storage tank (18), the hydraulic pump (12) and the second plate type heat exchanger (19) are connected in series on a pipeline of the second cold carrying circulation loop; the third cold-carrying temperature sensor (26) is arranged at a cold-carrying agent inlet of the precooler (28), the third electromagnetic valve (27) is communicated with the cold-carrying agent inlet and outlet of the precooler (28), and the third liquid storage tank (24), the hydraulic pump (12) and the third plate heat exchanger (25) are connected in series on a pipeline of a third cold-carrying circulation loop;

the low-temperature refrigeration system comprises a compressor (1), an oil-gas separator (2), a condenser (3), a gas-liquid separator (4), a first plate heat exchanger (5), a first expansion valve (6), a primary evaporator (7), a refrigerant expansion valve (8), a secondary evaporator (9) and a refrigerant heat exchanger (10), wherein the compressor (1), the oil-gas separator (2), the condenser (3), the gas-liquid separator (4), the first plate heat exchanger (5), the first expansion valve (6) and the primary evaporator (7) are sequentially connected to a pipeline of the low-temperature refrigeration system; the gas outlet of the primary evaporator (7) is connected with the inlet of the compressor (1), and the liquid outlet is connected with the inlet of the refrigerant heat exchanger (10); the refrigerant expansion valve (8) is sequentially connected with the secondary evaporator (9) and the refrigerant heat exchanger (10); the secondary evaporator (9) is connected with the first refrigerating cycle loop in series at the refrigerating medium inlet and the refrigerating medium outlet; the refrigerant heat exchanger (10) is connected with an inlet of the compressor (1); and a low-temperature oil gas inlet of the first plate heat exchanger (5) is connected with an outlet of a third plate heat exchanger (25) of the third cold-carrying circulation loop.

2. The indirect oil gas condensing and recovering device according to claim 1, which is characterized in that: the first oil-gas temperature sensor (29), the second oil-gas temperature sensor (31) and the third oil-gas temperature sensor (33) are respectively connected with a first electromagnetic valve (14), a second electromagnetic valve (21) and a third electromagnetic valve (27) which are used for controlling the flow of refrigerating medium of the deep cooler (16), the shallow cooler (23) and the precooler (28).

3. The indirect oil gas condensing and recovering device according to claim 1, which is characterized in that: the condenser (3) is of a tube-fin heat exchanger structure.

4. The indirect oil gas condensing and recovering device according to claim 1, which is characterized in that: the secondary refrigerant is low-temperature secondary refrigerant.

5. The indirect oil gas condensing and recovering device according to claim 1, which is characterized in that: the compressor (1) is a screw compressor.

6. The indirect oil gas condensation recovery device and the recovery process thereof according to claim 1, which is characterized in that: and heat insulation layers are arranged on the outer surfaces of the deep cooler (16), the shallow cooler (23) and the precooler (28).

7. The indirect oil gas condensation recovery device and the recovery process thereof according to claim 1, which is characterized in that: and the pipeline of the secondary refrigerant, the oil-gas pipeline and the outer surface of the liquid storage tank for storing the secondary refrigerant are subjected to heat preservation treatment.

8. A recycling process of the indirect oil gas condensation recycling device according to any one of claims 1 to 7, which is characterized in that: the oil gas condensation recovery process utilizes a refrigeration system to complete the temperature control of the whole oil gas condensation stage; the oil gas condensation process goes through precooling stage, shallow cooling stage and cryrogenic stage in proper order, and the coolant in cryrogenic stage obtains refrigerating system's cold volume through the heat transfer, and the export low temperature oil gas in cryrogenic stage provides cold volume for the coolant in shallow cooling stage and precooling stage through the heat transfer, carries out indirect condensation to oil gas and retrieves, and it specifically includes following process:

a. the technical process of the low-temperature refrigeration system comprises the following steps:

the gaseous mixed refrigerant in the compressor (1) is compressed into a high-temperature and high-pressure state, and when the gaseous mixed refrigerant with lubricating oil passes through the oil-gas separator (2), the lubricating oil is separated out and returns to the compressor (1) through an oil return pipe; the high-temperature high-pressure gaseous mixed refrigerant enters a condenser (3) for heat exchange, most of the high-boiling gaseous refrigerant I in the mixed refrigerant is cooled and then cooled to a temperature below the boiling point, the gaseous refrigerant I is condensed into liquid refrigerant I, the low-boiling gaseous refrigerant II still exists in a gaseous state, the gas-liquid two-phase mixed refrigerant is separated in a gas-liquid separator (4), the gaseous refrigerant II flows out of the top of the gas-liquid separator (4), the liquid refrigerant I flows out of the bottom of the gas-liquid separator (4), and after the liquid refrigerant I exchanges heat with low-temperature oil gas from a third plate heat exchanger (25) through a first plate heat exchanger (5), the temperature of the liquid refrigerant I is further reduced, the liquid refrigerant I is changed into a low-temperature low-pressure state under the pressure reducing and throttling action of a first expansion valve (6), and then enters a primary evaporator (7) for exchanging heat with the gaseous refrigerant II from the top of the gas-liquid separator (4), and the gaseous refrigerant II is, the liquid refrigerant I in a low-temperature and low-pressure state is gasified into a gaseous refrigerant I after absorbing the heat of the gaseous refrigerant II in the primary evaporator (7); meanwhile, liquid refrigerant II in the primary evaporator (7) enters a refrigerant heat exchanger (10) to exchange heat with low-temperature refrigerant from a refrigerant channel outlet of a secondary evaporator (9), the temperature of the liquid refrigerant II is further reduced and then flows through a refrigerant expansion valve (8), the liquid refrigerant II becomes a low-temperature and low-pressure state under the pressure reduction and throttling action of the refrigerant expansion valve (8), the temperature is reduced again when the liquid refrigerant II enters the secondary evaporator (9), the low-temperature liquid refrigerant II exchanges heat with secondary refrigerant in the secondary evaporator (9), the liquid refrigerant II continuously exchanges heat with the liquid refrigerant II from the primary evaporator (7) when passing through the refrigerant heat exchanger (10), the liquid refrigerant II is completely gasified after absorbing heat, and the gasified gaseous refrigerant I and the gaseous refrigerant II are mixed and then return to an inlet of the compressor (1);

b. the oil gas conveying system comprises the following technical processes:

the external oil gas enters the precooler (28) to exchange heat with the secondary refrigerant in the tube pass, the temperature of the oil gas is reduced, and high boiling point components in the oil gas are condensed into liquid which is accumulated at the bottom of the precooler (28) and discharged from an oil discharge port; low-boiling-point oil gas enters a shell pass of the shallow cooler (23) from an oil gas outlet of the precooler (28), exchanges heat with secondary refrigerant in a tube pass of the shallow cooler (23), the temperature of the oil gas is reduced again, one part of the oil gas is condensed into liquid and is discharged from an oil discharge port, the other part of the oil gas enters a shell pass of the deep cooler (16) from the oil gas outlet of the shallow cooler (23) and exchanges heat with the secondary refrigerant in the tube pass of the deep cooler (16), the temperature of the oil gas is reduced again, one part of components are condensed into liquid and are discharged from an oil discharge port, low-temperature oil gas passes through a second plate heat exchanger (19) and a third plate heat exchanger (25) in sequence from an oil gas outlet of the deep cooler (16), the temperature is reduced again, and finally the low-temperature oil gas exchanges heat with liquid refrigerant of a low-temperature refrigeration system through a first plate heat exchanger (5) and is cooled;

c. the process of the cold carrying system comprises the following steps:

the method comprises the following steps that low-temperature secondary refrigerant coming out of a tube pass of a chiller (16) enters a secondary evaporator (9) of a low-temperature refrigeration system to exchange heat with low-temperature liquid refrigerant, the temperature of the secondary refrigerant is reduced, the secondary refrigerant enters a first liquid storage tank (11) to be stored, the flow of the secondary refrigerant is pushed by a hydraulic pump (12), according to the change of oil-gas thermal load, when a first oil-gas temperature sensor (29) detects that the temperature of oil gas at an outlet of the chiller (16) is lower than a specified value, a first electromagnetic valve (14) is opened, and when the temperature of the oil gas at the outlet of the chiller (16) is higher than the specified value, the first electromagnetic valve (14) is closed, so that the flow of the secondary refrigerant entering the chiller (16) is adjusted, and the temperature of the oil gas at the outlet of; the low-temperature oil gas at the outlet of the deep cooler (16) enters a second plate heat exchanger (19) to exchange heat with low-temperature secondary refrigerant from a second liquid storage tank (18), the temperature of the secondary refrigerant is reduced again, a second secondary cold temperature sensor (22) monitors the temperature of a secondary refrigerant inlet of the shallow cooler (23), and the secondary refrigerant in the first liquid storage tank (11) is bypassed to the secondary refrigerant inlet of the shallow cooler (23) by controlling a first bypass electromagnetic valve (13) to provide cold energy, so that the temperature is kept at a specified value; the secondary refrigerant enters the tube pass of the shallow cooler (23) to exchange heat with oil gas outside the tube, the temperature of the oil gas rises, when the second oil gas temperature sensor (31) detects that the temperature of the oil gas at the outlet of the shallow cooler (23) changes and exceeds a specified value, the switch of the second electromagnetic valve (21) is opened to bypass the secondary refrigerant on the first secondary cooling circulation loop, so that the temperature of the oil gas at the outlet of the shallow cooler (23) is kept at the specified value; the oil gas from the second plate heat exchanger (19) enters a third plate heat exchanger (25) to exchange heat with the secondary refrigerant from a third liquid storage tank (24), the temperature of the secondary refrigerant is reduced, the temperature of the oil gas is increased, a third secondary cooling temperature sensor (26) is used for detecting the temperature of the secondary refrigerant inlet of the precooler (28), and when the temperature exceeds a specified value, a second bypass electromagnetic valve (20) is opened to bypass the secondary refrigerant in the second liquid storage tank (18) to the secondary refrigerant inlet of the precooler (28) to provide cold energy, so that the temperature is kept at the specified value; the low-temperature secondary refrigerant enters the tube pass of the precooler (28) to exchange heat with oil gas outside the tube, so that the oil gas temperature is reduced, and when the third oil gas temperature sensor (33) detects that the oil gas temperature at the outlet of the precooler (28) changes, the flow of the secondary refrigerant entering the precooler (28) is adjusted by controlling the switch of the third electromagnetic valve (27), so that the oil gas temperature at the outlet of the precooler (28) is kept at a specified value.

Technical Field

The invention belongs to the technical field of oil gas recovery, and particularly relates to an indirect oil gas condensation recovery device and a recovery process thereof.

Background

A large amount of loss and waste are generated in the storage and transportation processes of petroleum series products, oil gas comprises a plurality of hydrocarbon organic compounds, and chemical smoke can be formed due to improper treatment, so that the safety production is endangered, and the environment is polluted. In recent years, research and engineering on oil gas recovery and utilization are receiving wide attention, and in order to meet the national oil gas emission standard, an oil gas recovery processing device must be installed to recover and process light hydrocarbon components in oil gas, and currently, four existing oil gas processing methods are a condensation method, an absorption method, an adsorption method and a membrane separation method.

The common oil gas condensing and recovering method is one direct cooling method with direct heat exchange between refrigerant and oil gas. The biggest disadvantages of this method are: the change of oil-gas flow and temperature in the oil-gas treatment place is large, which means that the load change of oil-gas treatment is large, so that the working of the refrigerating system is unstable, and the working performance of the refrigerating system is greatly influenced; and the other is an indirect cooling mode of heat exchange between the secondary refrigerant and oil gas, and the change of oil gas load can be responded by adjusting the temperature and the flow of the secondary refrigerant, so that the system can stably run.

However, in the existing oil gas recovery method using the secondary refrigerant, the system structure is often complex, a plurality of refrigeration systems are required to be designed to provide oil gas treatment temperatures in different stages, the control of the system is correspondingly complex, the energy consumption is high, the recovery of cold energy is not considered, and the operation cost is high.

Disclosure of Invention

The device utilizes a refrigerating system to complete temperature control of the whole oil gas condensation stage, and adopts a process method that the oil gas condensation process is sequentially carried out in stages of a pre-cooling stage, a shallow cooling stage and a deep cooling stage, namely, cold energy of the refrigerating system is obtained by secondary refrigerant in the deep cooling stage through heat exchange, low-temperature oil gas at an outlet of the deep cooling stage provides supercooling for the secondary refrigerant in the shallow cooling stage and the pre-cooling stage through heat exchange, indirect condensation and recovery are carried out on the oil gas, the cold energy of the oil gas is effectively utilized, and the whole energy consumption of the refrigerating system is reduced.

The purpose of the invention can be realized by adopting the following technical scheme: an indirect oil gas condensation recovery device and a recovery process thereof, wherein the recovery device comprises: the system comprises an oil gas conveying system, a cold carrying system and a low-temperature refrigerating system; the oil-gas conveying system comprises a deep cooler, a shallow cooler and a precooler; the low-temperature oil and gas outlets of the deep cooler, the shallow cooler and the precooler are respectively provided with a first oil and gas temperature sensor, a second oil and gas temperature sensor and a third oil and gas temperature sensor, the oil and gas inlets are respectively provided with a first oil and gas inlet temperature sensor, a second oil and gas inlet temperature sensor and a third oil and gas inlet temperature sensor, and the bottoms of the deep cooler, the shallow cooler and the precooler are respectively provided with a condensed oil discharge port; a fan is arranged on an oil-gas inlet pipeline of the precooler, and an oil-gas outlet of the precooler is communicated with an oil-gas inlet of the shallow cooler; the oil-gas outlet of the shallow cooler is communicated with the oil-gas inlet of the deep cooler; an oil gas outlet of the deep cooler is communicated with the second plate heat exchanger;

the cold-carrying system comprises a first cold-carrying circulation loop, a second cold-carrying circulation loop and a third cold-carrying circulation loop which are respectively connected with the cold-carrying inlets and outlets of the deep cooler, the shallow cooler and the precooler; the first cold-carrying circulation loop consists of a first cold-carrying temperature sensor, a first bypass electromagnetic valve, a first liquid storage tank, a hydraulic pump and an expansion tank; the second cold-carrying circulation loop consists of a second cold-carrying temperature sensor, a second bypass electromagnetic valve, a second plate heat exchanger and a second liquid storage tank; the third cold-carrying circulation loop consists of a third cold-carrying temperature sensor, a third electromagnetic valve, a third plate heat exchanger and a third liquid storage tank; the first cold-carrying temperature sensor is arranged at a cold-carrying agent inlet of the chiller, one end of a first bypass electromagnetic valve is connected with the first cold-carrying temperature sensor at the cold-carrying agent inlet of the chiller, the other end of the first bypass electromagnetic valve is connected with a second cold-carrying temperature sensor in a second cold-carrying circulation loop, the first electromagnetic valve is communicated with the cold-carrying agent inlet and outlet of the chiller, and the first liquid storage tank, the hydraulic pump and the expansion tank are connected in series on a pipeline of the first cold-carrying circulation loop; the second cold-carrying temperature sensor is arranged at a cold-carrying agent inlet of the shallow cooler, one end of a second bypass electromagnetic valve is connected with an inlet of a second plate heat exchanger in a second cold-carrying circulation loop, the other end of the second bypass electromagnetic valve is connected with a third cold-carrying temperature sensor in a third cold-carrying circulation loop, the second electromagnetic valve is communicated with the cold-carrying agent inlet and outlet of the shallow cooler, and the second liquid storage tank, the hydraulic pump and the second plate heat exchanger are connected in series on a pipeline of the second cold-carrying circulation loop; the third cold-carrying temperature sensor is arranged at a cold-carrying agent inlet of the precooler, the third electromagnetic valve is communicated with the cold-carrying agent inlet and outlet of the precooler, and the third liquid storage tank, the hydraulic pump and the third plate heat exchanger are connected in series on a pipeline of a third cold-carrying circulation loop;

the low-temperature refrigeration system comprises a compressor, an oil-gas separator, a condenser, a gas-liquid separator, a first plate heat exchanger, a first expansion valve, a primary evaporator, a refrigerant expansion valve, a secondary evaporator and a refrigerant heat exchanger, wherein the compressor, the oil-gas separator, the condenser, the gas-liquid separator, the first plate heat exchanger, the first expansion valve and the primary evaporator are sequentially connected to a pipeline of the low-temperature refrigeration system; the gas outlet of the primary evaporator is connected with the inlet of the compressor, and the liquid outlet of the primary evaporator is connected with the inlet of the refrigerant heat exchanger; the refrigerant expansion valve is sequentially connected with the secondary evaporator and the refrigerant heat exchanger; the secondary evaporator has a secondary refrigerant inlet and a secondary refrigerant outlet connected in series in the first secondary cooling circulation loop; the refrigerant heat exchanger is connected with an inlet of the compressor; and a low-temperature oil gas inlet of the first plate heat exchanger is connected with an outlet of a third plate heat exchanger of a third cold-carrying circulation loop.

The first oil gas temperature sensor, the second oil gas temperature sensor and the third oil gas temperature sensor are respectively connected with a first electromagnetic valve, a second electromagnetic valve and a third electromagnetic valve which are used for controlling the flow of secondary refrigerant of the deep cooler, the shallow cooler and the precooler.

The condenser is of a tube-fin heat exchanger structure.

The secondary refrigerant is low-temperature secondary refrigerant.

The compressor is a screw compressor.

And the outer surfaces of the precooler, the shallow cooler and the deep cooler are provided with heat-insulating layers.

And the pipeline of the secondary refrigerant, the oil-gas pipeline and the outer surface of the liquid storage tank for storing the secondary refrigerant are subjected to heat preservation treatment.

The indirect oil gas condensation recovery process comprises the following steps:

a. the technical process of the low-temperature refrigeration system comprises the following steps:

the gaseous mixed refrigerant in the compressor is compressed into a high-temperature and high-pressure state, and when the gaseous mixed refrigerant with lubricating oil passes through the oil-gas separator, the lubricating oil is separated out and returns to the compressor through an oil return pipe; the high-temperature high-pressure gaseous mixed refrigerant enters a condenser for heat exchange, most of high-boiling gaseous refrigerant I in the mixed refrigerant is cooled and then cooled to a temperature below the boiling point, the gaseous refrigerant I is condensed into liquid refrigerant I, low-boiling gaseous refrigerant II still exists in a gaseous state, gas-liquid two-phase mixed refrigerant is separated in a gas-liquid separator, gaseous refrigerant II exits from the top of the gas-liquid separator, liquid refrigerant I flows out from the bottom of the gas-liquid separator, the temperature of the liquid refrigerant I is further reduced after the liquid refrigerant I is subjected to heat exchange with low-temperature oil gas from a third plate heat exchanger through a first plate heat exchanger, the liquid refrigerant I becomes a low-temperature and low-pressure state under the pressure reduction and throttling action of a first expansion valve, the liquid refrigerant I enters a primary evaporator for heat exchange with the gaseous refrigerant II from the top of the gas-liquid separator, the temperature of the gaseous refrigerant II is reduced to a temperature below the boiling point after the gaseous refrigerant II is cooled and liquefied into Media I; meanwhile, liquid refrigerant II in the primary evaporator enters a refrigerant heat exchanger to exchange heat with low-temperature refrigerant from a refrigerant channel outlet of the secondary evaporator, the temperature of the liquid refrigerant II is further reduced and then flows through a refrigerant expansion valve, the liquid refrigerant II becomes a low-temperature and low-pressure state under the pressure reduction and throttling action of the refrigerant expansion valve, the temperature is reduced again when the liquid refrigerant II enters the secondary evaporator again, the low-temperature liquid refrigerant II exchanges heat with secondary refrigerant in the secondary evaporator, the liquid refrigerant II continuously exchanges heat with the liquid refrigerant II from the primary evaporator when flowing through the refrigerant heat exchanger, the liquid refrigerant II is completely gasified after absorbing heat, and the gasified mixed refrigerant returns to the inlet of the compressor again;

b. the oil gas conveying system comprises the following technical processes:

the external oil gas enters the precooler to exchange heat with the secondary refrigerant in the tube pass, the temperature of the oil gas is reduced, and high-boiling-point components in the oil gas are condensed into liquid, accumulated at the bottom of the precooler and discharged from an oil discharge port; low-boiling-point oil gas enters a shallow cooler shell pass from an oil gas outlet of the precooler and exchanges heat with secondary refrigerant in a tube pass of the shallow cooler, the temperature of the oil gas is reduced again, one part of the oil gas is condensed into liquid and is discharged from an oil discharge port, the other part of the oil gas enters the deep cooler shell pass from an oil gas outlet of the shallow cooler and exchanges heat with the secondary refrigerant in the tube pass of the deep cooler, the temperature of the oil gas is reduced again, one part of components is condensed into liquid and is discharged from the oil discharge port, low-temperature oil gas passes through a second plate heat exchanger and a third plate heat exchanger in sequence from an oil gas outlet of the deep cooler, the temperature of the low-temperature oil gas is reduced again, finally, the low-temperature oil gas exchanges heat with liquid refrigerant of a low-temperature refrigerating;

c. the process of the cold carrying system comprises the following steps:

the method comprises the following steps that low-temperature secondary refrigerant coming out of a pipe pass of a chiller enters a secondary evaporator of a low-temperature refrigeration system to exchange heat with low-temperature liquid refrigerant, the temperature of the secondary refrigerant is reduced, the secondary refrigerant enters a first liquid storage tank to be stored, the flow of the secondary refrigerant is pushed by a hydraulic pump, and according to the change of oil-gas thermal load, when a first oil-gas temperature sensor detects that the temperature of oil gas at an outlet of the chiller is lower than a specified value, a first electromagnetic valve is opened; when the first oil-gas temperature sensor detects that the oil-gas temperature at the outlet of the chiller is higher than a specified value, the first electromagnetic valve is closed to adjust the flow of the secondary refrigerant entering the chiller, so that the oil-gas temperature at the outlet of the chiller is kept constant; the low-temperature oil gas at the outlet of the deep cooler enters a second plate heat exchanger to exchange heat with low-temperature secondary refrigerant from a second liquid storage tank, the temperature of the secondary refrigerant is reduced again, a second secondary cooling temperature sensor monitors the temperature of a secondary refrigerant inlet of the shallow cooler, and the secondary refrigerant in the first liquid storage tank is bypassed to the secondary refrigerant inlet of the shallow cooler by controlling a first bypass electromagnetic valve to provide cooling capacity, so that the temperature is kept at a specified value; the secondary refrigerant enters the tube pass of the shallow cooler to exchange heat with oil gas outside the tube, the temperature of the oil gas rises, when the second oil gas temperature sensor detects that the temperature of the oil gas at the outlet of the shallow cooler changes and exceeds a specified value, a switch of a second electromagnetic valve is opened to bypass the secondary refrigerant on the first secondary refrigerant circulation loop, so that the temperature of the oil gas at the outlet of the shallow cooler is kept at the specified value; the oil gas from the second plate heat exchanger enters a third plate heat exchanger to exchange heat with the secondary refrigerant from a third liquid storage tank, the temperature of the secondary refrigerant is reduced, the temperature of the oil gas is increased, a third secondary cooling temperature sensor is used for detecting the temperature of a secondary refrigerant inlet of the precooler, and when the temperature exceeds a specified value, a second bypass electromagnetic valve is opened to bypass the secondary refrigerant from the second liquid storage tank to the secondary refrigerant inlet of the precooler to provide cold energy so that the temperature is kept at the specified value; the low-temperature secondary refrigerant enters the tube pass of the precooler to exchange heat with oil gas outside the tube, so that the temperature of the oil gas is reduced, and when the third oil gas temperature sensor detects that the temperature of the oil gas at the outlet of the precooler changes, the flow of the secondary refrigerant entering the precooler is adjusted by controlling the switch of the third electromagnetic valve, so that the temperature of the oil gas at the outlet of the precooler is kept at a specified value.

Compared with the prior art, the invention has the beneficial effects that:

(1) the invention recovers the cold energy of the oil gas by the heat exchange between the secondary refrigerant and the oil gas at the outlet of the deep cooler, is used for the condensation and separation of the oil gas in the shallow cooler and the precooler, only one refrigerating system is arranged in the whole condensation process to directly provide a cold source for the deep cooling stage, the structure is simple, the control is convenient, the cold energy of the oil gas is effectively recycled, the electric energy consumed by the refrigerating system for preparing equivalent cold energy is effectively reduced, and the overall energy consumption of the system is low.

(2) In the invention, the cold energy of the refrigerating system is only provided for the cold-carrying circulation loop of the deep cooler, and the cold-carrying agent in the cold-carrying circulation loop of the deep cooler can be bypassed to the cold-carrying circulation loops of the shallow cooler and the precooler, and the flow of the cold-carrying agent entering the precooler, the shallow cooler and the deep cooler can be freely adjusted under the action of the bypass electromagnetic valve, so that the oil-gas treatment temperature is always maintained in a set range.

(3) The invention utilizes the low-temperature oil gas tail gas to provide supercooling for the refrigerant, realizes cold quantity recovery, further saves resources and reduces energy consumption.

(4) According to the invention, the refrigerant in the low-temperature state provides supercooling for the refrigerant in the high-temperature state, so that the temperature of the refrigerant for transferring a cold source to the secondary refrigerant is lower, and the energy efficiency of a refrigeration system is improved; on the other hand, the cold source is transferred to the low-temperature gaseous refrigerant for one heat recovery, so that the phenomenon that the suction temperature is too low is avoided.

Drawings

FIG. 1 is a schematic structural diagram of the working principle of an embodiment of the present invention;

the labels in the figure are: 1. a compressor, 2, an oil-gas separator, 3, a condenser, 4, a gas-liquid separator, 5, a first plate heat exchanger, 6, a first expansion valve, 7, a primary evaporator, 8, a refrigerant expansion valve, 9, a secondary evaporator, 10, a refrigerant heat exchanger, 11, a first liquid storage tank, 12, a hydraulic pump, 13, a first bypass electromagnetic valve, 14, a first electromagnetic valve, 15, a first cold-carrying temperature sensor, 16, a deep cooler, 17, an expansion tank, 18, a second liquid storage tank, 19, a second plate heat exchanger, 20, a second bypass electromagnetic valve, 21, a second electromagnetic valve, 22, a second cold-carrying temperature sensor, 23, a shallow cooler, 24, a third liquid storage tank, 25, a third plate heat exchanger, 26, a third cold-carrying temperature sensor, 27, a third electromagnetic valve, 28 and a precooler,

29. the oil gas inlet temperature sensor comprises a first oil gas temperature sensor, 30, a first oil gas inlet temperature sensor, 31, a second oil gas temperature sensor, 32, a second oil gas inlet temperature sensor, 33, a third oil gas temperature sensor, 34, a third oil gas inlet temperature sensor, 35, a fan, 36, an oil gas inlet, 37 and an oil gas outlet.

Detailed Description

The following detailed description of embodiments of the invention is provided in connection with the accompanying drawings, in which:

the drawings are only for purposes of illustration and are not to be construed as limiting the invention. For a better understanding of the following embodiments, certain features of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.

In the embodiment shown in fig. 1, an indirect oil gas condensation recovery device and a recovery process thereof, the recovery device comprises: the system comprises an oil gas conveying system, a cold carrying system and a low-temperature refrigerating system; the oil and gas delivery system comprises a deep cooler 16, a shallow cooler 23 and a precooler 28; the cold-carrying system comprises a first cold-carrying circulation loop, a second cold-carrying circulation loop and a third cold-carrying circulation loop which are respectively connected with the cold-carrying inlets and outlets of the deep cooler 16, the shallow cooler 23 and the precooler 28; the low-temperature refrigeration system comprises a compressor 1, an oil-gas separator 2, a condenser 3, a gas-liquid separator 4, a first plate heat exchanger 5, a first expansion valve 6, a primary evaporator 7, a refrigerant expansion valve 8, a secondary evaporator 9 and a refrigerant heat exchanger 10.

The low-temperature oil-gas outlets of the deep cooler 16, the shallow cooler 23 and the precooler 28 are respectively provided with a first oil-gas temperature sensor 29, a second oil-gas temperature sensor 31 and a third oil-gas temperature sensor 33 which are used for detecting the temperature of the oil-gas flowing out of the outlets of the deep cooler 16, the shallow cooler 23 and the precooler 28; a first oil gas inlet temperature sensor 30, a second oil gas inlet temperature sensor 32 and a third oil gas inlet temperature sensor 34 are respectively arranged at the oil gas inlet and used for detecting the temperature of oil gas entering the deep cooler 16, the shallow cooler 23 and the precooler 28; the bottoms of the deep cooler 16, the shallow cooler 23 and the precooler 28 are respectively provided with a condensed oil discharge port; an oil gas outlet of the chiller 16 is communicated with a second plate heat exchanger 19 of the cold carrying system; the oil gas outlet of the shallow cooler 23 is communicated with the oil gas inlet of the deep cooler 16; a fan 35 is arranged on an oil-gas inlet pipeline of the precooler 28, and an oil-gas outlet of the precooler 28 is communicated with an oil-gas inlet of the shallow cooler 23; the outer surfaces of the deep cooler 16, the shallow cooler 23 and the precooler 28 are all provided with insulating layers.

The first cold-carrying circulation loop consists of a first liquid storage tank 11, a hydraulic pump 12, a first bypass electromagnetic valve 13, a first electromagnetic valve 14, a first cold-carrying temperature sensor 15 and an expansion tank 17; the first cold-carrying temperature sensor 15 is arranged at a cold-carrying agent inlet of the chiller 16 and used for detecting the temperature of cold-carrying agent entering the chiller 16, one end of the first bypass electromagnetic valve 13 is connected with the first cold-carrying temperature sensor 15 at the cold-carrying agent inlet of the first cold-carrying circulation loop, and the other end is connected with the second cold-carrying temperature sensor 22 in the second cold-carrying circulation loop and used for bypassing the cold-carrying agent in the first cold-carrying circulation loop to the second cold-carrying circulation loop so as to supplement insufficient cold of the cold-carrying agent of the shallow cooler 23 and realize the accurate adjustment of the temperature of the cold-carrying agent at the inlet of the shallow cooler 23; the first electromagnetic valve 14 is communicated with a secondary refrigerant inlet and a secondary refrigerant outlet of the chiller 16, is connected with a first oil-gas temperature sensor 29 at an oil-gas outlet of the chiller 16 and is used for adjusting the flow rate of the secondary refrigerant entering the chiller 16, the first liquid storage tank 11, the hydraulic pump 12 and the expansion tank 17 are connected in series on a pipeline of a first secondary cooling circulation loop, the first liquid storage tank 11 is used for storing low-temperature secondary refrigerant, the hydraulic pump 12 is used for pushing the flow of the secondary refrigerant, and the expansion tank 17 is used for maintaining the pressure in the first secondary cooling circulation loop;

the second cold-carrying circulating loop consists of a second liquid storage tank 18, a second plate type heat exchanger 19, a second bypass electromagnetic valve 20, a second electromagnetic valve 21 and a second cold-carrying temperature sensor 22; the second cold-carrying temperature sensor 22 is arranged at a cold-carrying agent inlet of the shallow cooler 23 and used for detecting the temperature of cold-carrying agent entering the shallow cooler 23, one end of the second bypass electromagnetic valve 20 is connected with a cold-carrying agent inlet of the second plate heat exchanger 19 of the second cold-carrying circulation loop, and the other end of the second bypass electromagnetic valve is connected with a third cold-carrying temperature sensor 26 in the third cold-carrying circulation loop and used for bypassing the cold-carrying agent in the second cold-carrying circulation loop to the third cold-carrying circulation loop so as to supplement the insufficient cold of the cold-carrying agent in the precooler 28 and realize the accurate adjustment of the temperature of the cold-carrying agent at the inlet of the precooler 28; the second electromagnetic valve 21 is communicated with the secondary refrigerant inlet and outlet of the shallow cooler 23, is connected with a second oil-gas temperature sensor 31 at the oil-gas outlet of the shallow cooler 23, and is used for adjusting the flow rate of the secondary refrigerant entering the shallow cooler 23 to maintain the oil-gas temperature at the outlet of the shallow cooler 23 within a set range, and the second reservoir 18, the hydraulic pump 12 and the second plate heat exchanger 19 are connected in series on a pipeline of a second secondary cooling circulation loop;

the third cold-carrying circulation loop consists of a third liquid storage tank 24, a third plate heat exchanger 25, a third cold-carrying temperature sensor 26 and a third electromagnetic valve 27; the third cold-carrying temperature sensor 26 is arranged at the cold-carrying agent inlet of the precooler 28 and is used for detecting the temperature of the cold-carrying agent entering the precooler 28, the third electromagnetic valve 27 is communicated with the cold-carrying agent inlet and outlet of the precooler 28 and is connected with the third oil-gas temperature sensor 33 at the oil-gas outlet of the precooler 28 and is used for adjusting the flow rate of the cold-carrying agent entering the precooler 28, and the third liquid storage tank 24, the hydraulic pump 12 and the third plate heat exchanger 25 are connected in series on a pipeline of the third cold-carrying circulation loop.

The compressor 1, the oil-gas separator 2, the condenser 3, the gas-liquid separator 4, the first plate heat exchanger 5, the first expansion valve 6 and the primary evaporator 7 of the low-temperature refrigeration system are sequentially connected to a pipeline of the low-temperature refrigeration system; the compressor 1 is a screw compressor and is used for compressing a gaseous refrigerant into a high-temperature and high-pressure state; the gaseous refrigerant outlet of the primary evaporator 7 is connected with the inlet of the compressor 1, the liquid refrigerant outlet is connected with the inlet of the refrigerant heat exchanger 8, and the primary evaporator 7 is used for reducing the temperature of the gaseous refrigerant and converting the gaseous refrigerant into a low-temperature liquid refrigerant; the refrigerant expansion valve 8 is sequentially connected with the secondary evaporator 9 and the refrigerant heat exchanger 10, and the refrigerant expansion valve 8 is used for decompressing and throttling the low-temperature liquid refrigerant to convert the low-temperature liquid refrigerant into the low-temperature and low-pressure liquid refrigerant; the secondary evaporator 9 is used for transferring the cold energy of the low-temperature and low-pressure liquid refrigerant to the secondary refrigerant entering the first cold-carrying circulation loop of the secondary evaporator 9, so that the refrigerant is converted into a gaseous low-temperature refrigerant, and a supercooling process is provided for the liquid refrigerant of the low-temperature refrigeration system; the refrigerant heat exchanger 10 is connected with an inlet of the compressor 1, and the refrigerant heat exchanger 10 is used for realizing heat exchange between low-temperature liquid refrigerant from the primary evaporator 7 and low-temperature gaseous refrigerant from the secondary evaporator 9 so as to reduce the temperature of the liquid refrigerant; and the low-temperature oil gas inlet of the first plate heat exchanger 5 is connected with the oil gas outlet of the third plate heat exchanger 25 of the third cold-carrying circulation loop.

The pipeline of the secondary refrigerant, the oil-gas pipeline and the outer surface of the liquid storage tank for storing the secondary refrigerant of the oil-gas recovery device are subjected to heat preservation treatment, so that the waste of cold energy is reduced, and resources are saved.

The specific process of the embodiment comprises the following steps:

a. the technical process of the low-temperature refrigeration system comprises the following steps:

the gaseous mixed refrigerant in the compressor 1 is compressed into a high-temperature and high-pressure state, and when the gaseous mixed refrigerant with lubricating oil passes through the oil-gas separator 2, the lubricating oil is separated out and returns to the compressor 1 through an oil return pipe; the high-temperature high-pressure gaseous mixed refrigerant enters the condenser 3, the condenser 3 is a tube-fin heat exchanger, the gaseous mixed refrigerant exchanges heat with flowing air between outer fins of tubes, most of high-boiling gaseous refrigerant R600a in the mixed refrigerant is cooled to the temperature below the boiling point and condensed into liquid, while low-boiling gaseous refrigerant R23 is not liquefied and still exists in a gaseous state, the refrigerant with gas-liquid two phases is separated in the gas-liquid separator 4, gaseous refrigerant R23 flows out from the top of the gas-liquid separator 4, liquid refrigerant R600a flows out from the bottom of the gas-liquid separator 4, after passing through the first plate heat exchanger 5 and exchanging heat with low-temperature oil gas from the third plate heat exchanger 25, the temperature of the liquid refrigerant R600a is further reduced, the supercooling degree of the liquid refrigerant is increased, the liquid refrigerant R600a becomes a low-temperature and low-pressure state under the pressure reducing and throttling action of the first expansion valve 6, and then enters the primary evaporator 7 to exchange heat with the gaseous refrigerant R23 from the top of the gas, the gaseous refrigerant R23 is liquefied when cooled and the temperature is reduced to be lower than the boiling point, and the liquid refrigerant R600a in a low-temperature and low-pressure state is gasified after absorbing the heat of the gaseous refrigerant R23 in the primary evaporator 7; meanwhile, the liquid refrigerant R23 in the primary evaporator 7 enters the refrigerant heat exchanger 10 to exchange heat with the low-temperature refrigerant R23 from the outlet of the refrigerant channel of the secondary evaporator 9, the temperature of the liquid refrigerant R23 is further reduced, the liquid refrigerant flows through the refrigerant expansion valve 8, becomes a low-temperature and low-pressure state under the pressure reduction and throttling action of the refrigerant expansion valve 8, the temperature is reduced to-85 ℃ again when entering the secondary evaporator 9, the liquid refrigerant R23 exchanges heat with the secondary refrigerant in the secondary evaporator 9, at this time, the liquid refrigerant R23 may not be gasified, continuously exchanges heat with the liquid refrigerant R23 from the primary evaporator 7 when flowing through the refrigerant heat exchanger 10, and is completely gasified after absorbing heat, a certain supercooling degree is provided for the liquid refrigerant R23 from the primary evaporator 7, and the gasified refrigerant R23 and R600a are mixed and then return to the inlet of the compressor 1 again.

b. The oil gas conveying system comprises the following technical processes:

external oil gas enters from an oil gas inlet 36, enters the shell side of the precooler 28 under the drive of the fan 25, exchanges heat with secondary refrigerant in the tube side, the secondary refrigerant is low-temperature secondary refrigerant, the temperature of the oil gas is reduced from 30 ℃ to 5 ℃ after heat exchange, and after the oil gas is cooled, most of high-boiling-point components such as moisture, dimethylbenzene and the like in the oil gas are condensed into liquid, accumulated at the bottom of the precooler 28 and discharged from an oil discharge port of the precooler 28; the low-boiling-point oil gas from the oil gas outlet of the precooler 28 enters the shell pass of the shallow cooler 23 again to exchange heat with the secondary refrigerant in the tube pass of the shallow cooler 23, the temperature of the oil gas is reduced to-35 ℃ from 5 ℃, heavy hydrocarbon components of the oil gas can be condensed into liquid and discharged from the oil discharge port of the shallow cooler 23, the oil gas enters the shell pass of the deep cooler 16 from the oil gas outlet of the shallow cooler 23 to exchange heat with the secondary refrigerant in the tube pass of the deep cooler 16, the temperature of the oil gas is reduced to-65 ℃ from-35 ℃, partial light hydrocarbon components can be condensed into liquid and discharged from the oil discharge port of the deep cooler 16, the low-temperature oil gas passes through the second plate heat exchanger 19 of the second secondary cooling circulation loop and the third plate heat exchanger 25 of the third secondary cooling circulation loop in sequence from the oil gas outlet of the deep cooler 16 to-15 ℃, and finally the oil gas passes through the first plate heat exchanger 5 to exchange heat with the liquid state R600a of the low-temperature refrigeration, the refrigerant is cooled, a supercooling process is provided for the refrigerant, and finally the refrigerant is discharged from the oil gas outlet 37, so that supercooling is provided for the refrigerant by using the low-temperature oil gas tail gas, and cold recovery is realized.

c. The process of the cold carrying system comprises the following steps:

the low-temperature secondary refrigerant with the temperature of minus 60 ℃ coming out of the tube pass of the chiller 16 enters a first secondary refrigeration circulation loop, namely the low-temperature secondary refrigerant enters a secondary evaporator 9 of a low-temperature refrigeration system to exchange heat with a liquid refrigerant with the temperature of minus 85 ℃, the temperature of the secondary refrigerant is reduced to minus 75 ℃, then the secondary refrigerant enters a first liquid storage tank 11 to be stored, the secondary refrigerant is pushed by a hydraulic pump 12 to flow, and according to the change of oil-gas thermal load, when the first oil-gas temperature sensor 29 detects that the temperature of oil gas at the outlet of the chiller 16 is lower than a specified value of minus 66 ℃, a first electromagnetic valve 14 is opened; when the first oil-gas temperature sensor 29 detects that the temperature of the oil-gas at the outlet of the chiller 16 is higher than a specified value of-64 ℃, closing the first electromagnetic valve 14 so as to adjust the flow of the secondary refrigerant entering the chiller 16 and keep the temperature of the oil-gas at the outlet of the chiller 16 constant; the oil gas at the low temperature of minus 65 plus or minus 1 ℃ at the outlet of the chiller 16 enters a second plate heat exchanger 19 of a second refrigerating circulation loop to exchange heat with the refrigerating medium at the low temperature of minus 30 ℃ from a second liquid storage tank 18, and the temperature of the refrigerating medium is reduced to minus 45 ℃ again; the second cold-carrying temperature sensor 22 is used for monitoring the temperature of the cold-carrying agent at the inlet of the shallow cooler 23, and controlling the first bypass electromagnetic valve 13 to bypass the cold-carrying agent in the first liquid storage tank 11 to the cold-carrying agent inlet of the shallow cooler 23 so as to make up for the insufficient cold quantity of the cold-carrying agent of the shallow cooler 23 and keep the temperature of the cold-carrying agent at the inlet of the shallow cooler 23 at a specified value of minus or plus 45℃ or minus 1℃; the low-temperature secondary refrigerant enters a shallow cooler 23 tube pass to exchange heat with oil gas outside the tube, and the temperature is raised to-30 ℃; the second oil-gas temperature sensor 31 is used for detecting the oil-gas temperature at the outlet of the shallow cooler 23, and when the oil-gas temperature exceeds a specified value, the switch of the second electromagnetic valve 21 is opened to bypass the secondary refrigerant of the first liquid storage tank 11 on the first secondary cooling circulation loop, so as to make up the shortage of the cold quantity of the secondary refrigerant of the shallow cooler 23 and keep the oil-gas temperature at the outlet of the shallow cooler 23 at the specified value of minus 35 +/-1℃; the oil gas from the second plate heat exchanger 19 enters a third plate heat exchanger 25 to exchange heat with the coolant at 5 ℃ from a third liquid storage tank 24, the coolant is reduced from 5 ℃ to-5 ℃, the oil gas is increased from-35 ℃ to-15 ℃, a third coolant temperature sensor 26 is used for detecting the coolant inlet temperature of the precooler 25, the coolant in the second liquid storage tank 18 is bypassed to the coolant inlet of the precooler 28 by controlling the switch of a second bypass electromagnetic valve 20 to make up the insufficient coolant cold of the precooler 28, and the temperature of the inlet is kept at a specified value of- (5 +/-1) DEG C; the secondary refrigerant with the temperature of minus 5 ℃ enters the tube pass of the precooler 28 to exchange heat with oil gas outside the tube, the oil gas temperature is reduced to 5 ℃ from 30 ℃, the third oil gas temperature sensor 33 is used for detecting the oil gas temperature at the outlet of the precooler 28, and the flow rate of the secondary refrigerant entering the precooler 28 is adjusted by controlling the switch of the third electromagnetic valve 27, so that the oil gas temperature at the outlet of the precooler 28 is kept at (5 +/-1) DEG C.

The oil gas condensation recovery process sequentially passes through a precooling stage, a shallow cooling stage and a deep cooling stage, the cold-carrying agent in the deep cooling stage provides cold energy for the cold-carrying agent in the low-temperature refrigeration system through heat exchange, and the low-temperature oil gas at the outlet of the deep cooling stage provides cold energy for the cold-carrying agent in the shallow cooling stage and the precooling stage through heat exchange, so that the cold energy recovery is realized, the resources are further saved, and the energy consumption is reduced; when the temperature or the flow of the oil gas at the inlet of the deep cooling stage, the shallow cooling stage and the precooling stage changes in a small range, the cold carrying system can quickly adjust the flow of the secondary refrigerant introduced into each oil-gas heat exchanger, so that the temperature of the oil gas is always maintained in a set range, and the stable operation of each system is ensured.

The present invention is not limited to the prior art, and it should be understood that the above-mentioned embodiments are only examples for clearly illustrating the technical solutions of the present invention, and are not intended to limit the specific embodiments of the present invention. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention claims should be included in the protection scope of the present invention claims.