A low temperature refrigeration system for oil and gas liquefaction

Abstract

The present invention relates to the field of refrigeration devices, and in particular to a low-temperature refrigeration system for oil and gas liquefaction, including an air cooling mechanism, which includes an inverted isosceles trapezoidal heat sink, and the waistlines on both sides of the heat sink are respectively provided with a compression mechanism and an expansion mechanism in parallel, and the compression mechanism includes a compression cylinder, and the end of the compression cylinder is equipped with an exhaust check valve and connected to the air inlet end of the heat sink. The refrigeration device of the present invention can separate the incompletely liquefied refrigerant gas and liquid, so that the liquid refrigerant is used for oil and gas refrigeration, and the gaseous low-temperature refrigerant is used for oil and gas pre-cooling, thereby achieving the purpose of energy saving and avoiding the influence caused by the incomplete liquefaction of the refrigerant; the present invention allows the refrigerant to be incompletely liquefied, so that the refrigerant with a lower boiling point can be used to obtain a lower refrigeration temperature. The compression mechanism and the expansion mechanism of the present invention are both controlled by independent servo electric push rods, and the compressed air pressure of the compression mechanism and the negative pressure of the expansion mechanism can be flexibly adjusted according to the different boiling points of the refrigerant.

Description

Technical Field

[0001] The invention relates to the field of refrigeration devices, in particular to a low-temperature refrigeration system for oil and gas liquefaction. Background Art

[0002] There are two main ways to liquefy oil and gas. One is to pressurize the oil and gas to increase its boiling point to achieve liquefaction. The other is to refrigerate the oil and gas to reduce its temperature to below the boiling point so that the oil and gas are converted into liquid. The refrigeration and liquefaction of oil and gas generally needs to be carried out in multiple stages to gradually reduce the temperature of the oil and gas. During the process, low-temperature refrigeration equipment is needed to achieve this goal.

[0003] Conventional refrigeration equipment using refrigerant first compresses the refrigerant into liquefaction through a compressor, and then cools the liquid refrigerant through air cooling and other means. The cooled liquid refrigerant expands into a gas through an expansion valve. Since the energy remains unchanged but the density is greatly reduced, the temperature will drop rapidly to achieve the purpose of refrigeration. Existing refrigerant medium refrigeration equipment relies more on high-power compressors and consumes a lot of power. If the refrigerant compression pressure is insufficient, it is easy to cause insufficient liquefaction of the refrigerant, resulting in the refrigerant entering the air-cooled box being in a gas-liquid mixed state. The inclusion of gaseous refrigerant will reduce the refrigeration effect of the refrigerant. Therefore, the present invention proposes a low-power energy-saving refrigerant refrigeration device, which separates the incompletely liquefied refrigerant gas and liquid, so that the liquid refrigerant is used for oil and gas refrigeration, and the gaseous low-temperature refrigerant is used for oil and gas pre-cooling, thereby achieving the purpose of energy saving while avoiding the impact of incomplete liquefaction of the refrigerant. Summary of the invention

[0004] In view of the problem in the prior art that incomplete compression and liquefaction of the refrigerant leads to poor refrigeration effect, the present invention is proposed.

[0005] Therefore, an object of the present invention is to provide a low temperature refrigeration system for oil and gas liquefaction.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: a low-temperature refrigeration system for oil and gas liquefaction, comprising an air cooling mechanism, which comprises an inverted isosceles trapezoidal heat sink, and the waistlines on both sides of the heat sink are respectively and parallelly provided with a compression mechanism and an expansion mechanism, the compression mechanism comprises a compression cylinder, the end of the compression cylinder is equipped with an exhaust check valve and connected to the air inlet end of the heat sink; the expansion mechanism comprises an expansion cylinder, the end of the expansion cylinder is provided with an intake pressure difference control component, and the intake pressure difference control component is connected to the air outlet end of the heat sink, the expansion cylinder A piston is arranged inside, and a circular groove 1 is vertically processed at the low edge of the top surface of the piston, a circular groove 2 is processed at the bottom of the circular groove 1 of the piston and is parallel to the axis of the piston, and a circular groove 3 is processed on the inner wall of the circular groove 1 located near the middle of the piston and is parallel to the axis of the piston, and the circular groove 3 connects the circular groove 1 and the circular groove 2, a Z-shaped flow channel is penetrated between the bottom of the circular groove 2 and the bottom surface of the piston, and the circular groove 2 is sealingly and slidingly sleeved with a plunger, and a spring 1 is connected between the plunger and the flow channel port, and the port of the flow channel located on the bottom surface of the piston is connected to a discharge one-way valve.

[0007] As a preferred solution of the low-temperature refrigeration system for oil and gas liquefaction of the present invention, the air intake pressure difference control component includes a reducer, and the end of the reducer away from the expansion cylinder is sealed with a cylindrical pressure block, and a sealing plug and a spring are arranged between the pressure block and the reducer.

[0008] As a preferred solution of the low-temperature refrigeration system for oil and gas liquefaction of the present invention, wherein: the pressure block and the adapter are threadedly connected, and a nut is threadedly fastened between the circumferential wall of the pressure block and the end of the adapter, the pressure block is connected to the air outlet end of the heat sink through a high-pressure hose at one end away from the adapter, and a tapered hole is penetrated through the connecting end of the pressure block and the adapter, and the sealing plug is matched with the tapered hole, the spring 2 is a tapered spiral, and the small diameter end of the spring 2 is coaxially sleeved with the sealing plug.

[0009] As a preferred solution of the low-temperature refrigeration system for oil and gas liquefaction of the present invention, the axis of the expansion cylinder is at an angle of thirty degrees to the vertical direction, and the angle between the expansion cylinder and the compression cylinder is sixty degrees, and the compression cylinder and the expansion cylinder are both connected to a servo electric push rod.

[0010] As a preferred solution of the low-temperature refrigeration system for oil and gas liquefaction of the present invention, wherein: the heat sink is connected to an air collecting hood, and the outline of the air collecting hood matches the outline of the heat sink, a cooling fan is arranged in the middle of the air collecting hood, and the arc outer wall of the cooling fan is tangent to the three long sides of the air collecting hood.

[0011] As a preferred solution of the low-temperature refrigeration system for oil and gas liquefaction of the present invention, the outer walls of the compression cylinder and the expansion cylinder are fixedly connected to the wind collecting hood with brackets, and the ends of the two brackets are respectively fixedly sleeved on the compression cylinder and the expansion cylinder, and the other end of the bracket is in a plate shape and fixedly connected to the outer wall of the wind collecting hood.

[0012] As a preferred solution of the low-temperature refrigeration system for oil and gas liquefaction of the present invention, the port of the flow channel located on the bottom surface of the piston is arranged on the edge of the piston, and the bottom surface of the piston is coaxially fixedly connected with the push rod of the servo electric push rod along its axial direction.

[0013] As a preferred solution of the low-temperature refrigeration system for oil and gas liquefaction of the present invention, an adapter is fixedly connected in series between the housing of the servo electric push rod and the expansion cylinder, and the high-pressure hose connected to the discharge one-way valve passes through the adapter.

[0014] As a preferred solution of the low-temperature refrigeration system for oil and gas liquefaction of the present invention, wherein: an air intake check valve is also provided at the end of the compression cylinder, and a return check valve is also provided at the end of the expansion cylinder, and the flow direction of the return check valve is from inside the expansion cylinder to outside.

[0015] As a preferred embodiment of the low-temperature refrigeration system for oil and gas liquefaction of the present invention, the low-temperature liquid refrigerant discharged from the discharge check valve flows back to the compression cylinder air inlet check valve after passing through the heat exchanger for oil and gas refrigeration, and the low-temperature gaseous refrigerant discharged from the reflux check valve flows back to the compression cylinder air inlet check valve after passing through the heat exchanger for oil and gas pre-cooling.

[0016] Beneficial effects of the low-temperature refrigeration system for oil and gas liquefaction of the present invention:

[0017] 1. The refrigeration device of the present invention can separate the incompletely liquefied refrigerant gas and liquid, so that the liquid refrigerant is used for oil and gas refrigeration and the gaseous low-temperature refrigerant is used for oil and gas pre-cooling, thereby achieving the purpose of energy saving while avoiding the impact caused by incomplete liquefaction of the refrigerant;

[0018] 2. Since the present invention allows incomplete liquefaction of the refrigerant, the present invention can use a refrigerant with a lower boiling point to obtain a lower refrigeration temperature, and the compression mechanism and expansion mechanism of the present invention are both controlled by independent servo electric push rods, and the compressed air pressure of the compression mechanism and the negative pressure of the expansion mechanism can be flexibly adjusted according to the different boiling points of the refrigerant used, so that the present invention can be compatible with the use of refrigerants with different characteristics and flexibly control the refrigeration effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0020] Figure 1 Schematic diagram of the structure of a low-temperature refrigeration system for oil and gas liquefaction.

[0021] Figure 2 for Figure 1 Schematic diagram of the structure from another side perspective.

[0022] Figure 3 A partial structural cross-sectional view of a low-temperature refrigeration system for oil and gas liquefaction.

[0023] Figure 4 It is a cross-sectional view of the expansion cylinder structure.

[0024] Figure 5 It is a structural cross-sectional view of the piston.

[0025] Figure 6 It is a structural cross-sectional view of the pressure difference control component.

[0026] Figure 7 This is a block diagram of the working principle of the low-temperature refrigeration system used for oil and gas liquefaction.

[0027] In the figure: 100, air cooling mechanism; 101, heat sink; 102, air collecting hood; 103, cooling fan; 104, servo electric push rod; 105, adapter; 106, bracket; 200, compression mechanism; 201, compression cylinder; 202, exhaust check valve; 203, intake check valve; 300, expansion mechanism; 301, expansion cylinder; 302, piston; 303, plunger; 304, spring one; 305, discharge check valve; 306, reflux check valve; 307, pressure difference control component; 308, reducer; 309, pressure block; 310, sealing plug; 311, spring two; 312, nut; 302a, circular groove one; 302b, circular groove two; 302c, circular groove three; 302d, flow channel; 309a, tapered hole. DETAILED DESCRIPTION

[0028] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0029] Example, see Figure 1 to Figure 7This embodiment provides a low-temperature refrigeration system for oil-gas liquefaction, which can separate the incompletely liquefied refrigerant into gas and liquid, so that the liquid refrigerant is used for oil-gas refrigeration and the gaseous low-temperature refrigerant is used for oil-gas precooling, thereby achieving the purpose of energy saving while avoiding the impact caused by the incomplete liquefaction of the refrigerant. Figure 1 As shown, it includes an air cooling mechanism 100, which includes an inverted isosceles trapezoidal heat sink 101, and the waistlines on both sides of the heat sink 101 are respectively and parallelly provided with a compression mechanism 200 and an expansion mechanism 300, as shown in FIG. Figure 2 As shown, the compression mechanism 200 includes a compression cylinder 201, and an exhaust check valve 202 is installed at the end of the compression cylinder 201 and connected to the air inlet end of the heat sink 101; Figure 4 As shown, the expansion mechanism 300 includes an expansion cylinder 301, an air intake pressure difference control component 307 is provided at the end of the expansion cylinder 301, and the air intake pressure difference control component 307 is connected to the air outlet end of the heat dissipation box 101, as shown in FIG. Figure 5 As shown, a piston 302 is arranged in the expansion cylinder 301, and a circular groove 1 302a is vertically processed at the low edge of the top surface of the piston 302, a circular groove 2 302b is processed at the bottom of the circular groove 1 302a of the piston 302 and is parallel to the axis of the piston 302, and a circular groove 302c is processed on the inner wall of the circular groove 1 302a located near the middle of the piston 302 and is parallel to the axis of the piston 302, and the circular groove 302c connects the circular groove 1 302a and the circular groove 2 302b, a Z-shaped flow channel 302d is penetrated between the groove bottom of the circular groove 2 302b and the bottom surface of the piston 302, and the circular groove 2 302b is sealingly and slidably sleeved with a plunger 303, and a spring 1 304 is connected between the plunger 303 and the port of the flow channel 302d, and the port of the flow channel 302d located on the bottom surface of the piston 302 is connected with a discharge check valve 305.

[0030] Specifically, Figure 6 As shown, the intake pressure difference control component 307 includes a reducer 308, and the end of the reducer 308 away from the expansion cylinder 301 is sealed with a cylindrical pressure block 309, and a sealing plug 310 and a spring 2 311 are arranged between the pressure block 309 and the reducer 308, the pressure block 309 and the adapter are threadedly connected, and a nut 312 is threadedly fastened between the peripheral wall of the pressure block 309 and the end of the adapter, the end of the pressure block 309 away from the adapter is connected to the air outlet end of the heat sink 101 through a high-pressure hose, and a tapered hole 309a is opened through the connecting end of the pressure block 309 and the adapter, and the sealing plug 310 is matched with the tapered hole 309a, and the spring 2 311 is a tapered spiral, and the small diameter end of the spring 2 311 is coaxially sleeved with the sealing plug 310.

[0031] like Figure 1 and Figure 4As shown, the axis of the expansion cylinder 301 forms an angle of thirty degrees with the vertical direction, and the angle between the expansion cylinder 301 and the compression cylinder 201 is sixty degrees, the compression cylinder 201 and the expansion cylinder 301 are both connected to the servo electric push rod 104, the heat sink 101 is connected to the wind collecting hood 102, and the outline of the wind collecting hood 102 matches the outline of the heat sink 101, a cooling fan 103 is arranged in the middle of the wind collecting hood 102, and the arc outer wall of the cooling fan 103 is tangent to the three long sides of the wind collecting hood 102, the outer walls of the compression cylinder 201 and the expansion cylinder 301 are fixedly connected to the wind collecting hood 102 with a bracket 106, and the ends of the two brackets 106 are respectively fixedly sleeved on the compression cylinder 201 and the expansion cylinder 301, and the other end of the bracket 106 is plate-shaped and fixedly connected to the outer wall of the wind collecting hood 102.

[0032] like Figure 1 As shown, an adapter 105 is fixedly connected in series between the housing of the servo electric push rod 104 and the expansion cylinder 301, and a high-pressure hose connected to the discharge check valve 305 passes through the adapter 105. An intake check valve 203 is also provided at the end of the compression cylinder 201, and a return check valve 306 is also provided at the end of the expansion cylinder 301, and the conduction direction of the return check valve 306 is from the inside of the expansion cylinder 301 to the outside, as shown in FIG. Figure 5 As shown, the port of the flow channel 302d located at the bottom surface of the piston 302 is set at the edge of the piston 302, and the bottom surface of the piston 302 is coaxially fixedly connected with the push rod of the servo electric push rod 104 along its axial direction, as shown in FIG. Figure 7 As shown, the low-temperature liquid refrigerant discharged from the discharge check valve 305 flows back to the air intake check valve 203 of the compression cylinder 201 after passing through the heat exchanger for oil and gas refrigeration, and the low-temperature gaseous refrigerant discharged from the return check valve 306 flows back to the air intake check valve 203 of the compression cylinder 201 after passing through the heat exchanger for oil and gas pre-cooling.

[0033] The present invention is a refrigeration device that uses refrigerant as a working medium, and mainly provides a low-power energy-saving refrigeration function with a small flow rate, including making full use of the refrigeration effect of non-completely liquefied refrigerant in a low-power refrigeration state, separating the gaseous refrigerant and the liquid refrigerant in the low-temperature refrigerant, and then using the liquid refrigerant for refrigeration and the gaseous refrigerant for pre-cooling of oil and gas intake.

[0034] To achieve the above functions, the present invention also involves the following technical details:

[0035] The present invention mainly consists of a compression mechanism 200 responsible for compressing the refrigerant, an air cooling mechanism 100 responsible for cooling the high-pressure gaseous refrigerant, and an expansion mechanism 300 responsible for forced expansion and refrigeration of the normal-temperature gaseous refrigerant. Different from conventional low-power refrigerant refrigeration compression equipment, the present invention should use a refrigerant with a lower boiling point. The liquefaction of the refrigerant is not formed in the compression mechanism 200, but in the expansion mechanism 300. The piston 302 quickly draws negative pressure in the expansion cylinder 301, so that the high-pressure gaseous refrigerant after heat dissipation obtains a higher pressure difference than the conventional expansion valve, thereby realizing the liquefaction of the low-boiling-point refrigerant. At this time, the temperature of the liquefied refrigerant is already very low, and when the liquefied refrigerant enters the conventional expansion valve and expands into gas, the temperature will be lowered again, thereby exerting a better refrigeration effect on the oil and gas.

[0036] like Figure 3 and Figure 6 As shown, the conduction pressure of the pressure difference control component 307 is adjustable. By tightening the pressure block 309 relative to the reducer 308, more compression spring 2 311 is used to increase the preload force between the sealing plug 310 and the pressure block 309. At this time, a higher pressure difference is required between the air inlet end of the pressure difference control component 307 and the expansion cylinder 301 to push the sealing plug 310 to achieve air intake in the expansion cylinder 301. Since the diameter of the tapered hole 309a is limited, even when the sealing plug 310 is in an open state due to the differential pressure and the piston 302 quickly moves away from the pressure difference control component 307, the pressure difference between the air inlet end of the pressure difference control component 307 and the expansion cylinder 301 can still be increased or maintained, so that most of the refrigerant entering the expansion cylinder 301 can be quenched and liquefied.

[0037] like Figure 4 and Figure 5 As shown, since the internal volume of the expansion cylinder 301 is limited, the amount of liquefaction after each expansion of the refrigerant is small, so the inclined design of the expansion cylinder 301 is helpful for collecting the liquefied refrigerant. When the refrigerant is in the form of droplets, its adhesion makes the fluidity poor. Therefore, the inclined cylinder body design allows the refrigerant droplets to converge to the cylindrical generatrix path of the expansion cylinder 301 in a lower position through a shorter path, including the refrigerant droplets on the end face of the piston 302 will also be more likely to converge to the circular groove 1 302a. When the refrigerant droplets converge, the fluidity increases, and they are collected in the circular groove 2 302b through the circular groove 1 302a and the circular groove 302c. Figure 4 For example, the piston 302 is quickly pushed toward the return check valve 306 until the top of the plunger 303 abuts against the top of the expansion cylinder 301, and the plunger 303 is squeezed so that the plunger 303 squeezes the liquid refrigerant in the second circular groove 302b through the discharge check valve 305. Figure 7As shown, the squeezed liquid one-way valve enters the conventional oil-gas refrigeration heat exchanger for circulation and then returns to the compression mechanism 200 in a gaseous form to participate in compression again, while the gaseous refrigerant that has not been liquefied is squeezed out through the reflux one-way valve 306 and sent to the heat exchanger for pre-cooling before oil-gas refrigeration. After circulation, it still returns to the compression mechanism 200 in a gaseous form to participate in compression again.

[0038] like Figure 1 As shown, the air collecting hood of the present invention can guide the airflow refracted by the surface of the heat sink 101 to the area around the heat sink 101 that is not covered by the blades of the heat sink fan 103, thereby increasing the air cooling flow of the heat sink 101 and further optimizing the forced air cooling effect.

[0039] In summary, the refrigeration device of the present invention can separate the incompletely liquefied refrigerant gas and liquid, so that the liquid refrigerant is used for oil and gas refrigeration and the gaseous low-temperature refrigerant is used for oil and gas pre-cooling, thereby achieving the purpose of energy saving and avoiding the impact caused by incomplete liquefaction of the refrigerant; since the present invention allows incomplete liquefaction of the refrigerant, the present invention can use refrigerant with a lower boiling point to obtain a lower refrigeration temperature, and the compression mechanism 200 and the expansion mechanism 300 of the present invention are both controlled by independent servo electric push rods 104, and the compressed air pressure of the compression mechanism 200 and the negative pressure of the expansion mechanism 300 can be flexibly adjusted according to the different boiling points of the refrigerant used, so that the present invention can be compatible with the use of refrigerants with different characteristics and flexibly control the refrigeration effect.

[0040] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A low temperature refrigeration system for oil and gas liquefaction, characterized in that: It comprises an air cooling mechanism (100), which comprises an inverted isosceles trapezoidal heat sink (101), and a compression mechanism (200) and an expansion mechanism (300) are respectively arranged in parallel on the waistlines of both sides of the heat sink (101), and the compression mechanism (200) comprises a compression cylinder (201), and an exhaust check valve (202) is installed at the end of the compression cylinder (201) and connected to the air inlet end of the heat sink (101); The expansion mechanism (300) comprises an expansion cylinder (301), an air intake pressure difference control component (307) is arranged at the end of the expansion cylinder (301), and the air intake pressure difference control component (307) is connected to the air outlet end of the heat dissipation box (101), a piston (302) is arranged in the expansion cylinder (301), and a circular groove 1 (302a) is vertically processed at the low edge of the top end surface of the piston (302), and a circular groove 2 (302b) is processed at the bottom of the groove of the circular groove 1 (302a) parallel to the axis of the piston (302), and the circular groove 1 (302a) is located near the piston (3 02) The inner wall of the middle part is parallel to the axis of the piston (302) and is processed with a circular groove three (302c), and the circular groove three (302c) is connected to the circular groove one (302a) and the circular groove two (302b), and a Z-shaped flow channel (302d) is provided between the groove bottom of the circular groove two (302b) and the bottom surface of the piston (302), and the circular groove two (302b) is sealed and slidably sleeved with a plunger (303), and a spring one (304) is connected between the plunger (303) and the port of the flow channel (302d), and the port of the flow channel (302d) located on the bottom surface of the piston (302) is connected to a discharge check valve (305); An intake check valve (203) is also provided at the end of the compression cylinder (201) of the compression mechanism (200), and a return check valve (306) is also provided at the end of the expansion cylinder (301) of the expansion mechanism (300), and the flow direction of the return check valve (306) is from the inside of the expansion cylinder (301) of the expansion mechanism (300) to the outside. The low-temperature liquid refrigerant discharged by the discharge check valve (305) flows back to the intake check valve (203) of the compression cylinder (201) of the compression mechanism (200) after passing through a heat exchanger for oil and gas refrigeration, and the low-temperature gaseous refrigerant discharged by the return check valve (306) flows back to the intake check valve (203) of the compression cylinder (201) of the compression mechanism (200) after passing through a heat exchanger for oil and gas pre-cooling.

2. The low temperature refrigeration system for oil and gas liquefaction according to claim 1, characterized in that: The intake pressure difference control assembly (307) comprises a reducer (308), one end of the reducer (308) away from the expansion cylinder (301) is sealed with a cylindrical pressure block (309), and a sealing plug (310) and a second spring (311) are provided between the pressure block (309) and the reducer (308).

3. The low temperature refrigeration system for oil and gas liquefaction according to claim 2, characterized in that: The pressing block (309) and the adapter are threadedly connected, and a nut (312) is threadedly fastened between the peripheral wall of the pressing block (309) and the end of the adapter. The end of the pressing block (309) away from the adapter is connected to the air outlet end of the heat sink (101) via a high-pressure hose, and a tapered hole (309a) is provided through the connecting end of the pressing block (309) and the adapter, and the sealing plug (310) is matched with the tapered hole (309a). The second spring (311) is a tapered spiral, and the small-diameter end of the second spring (311) is coaxially sleeved with the sealing plug (310).

4. The low temperature refrigeration system for oil and gas liquefaction according to claim 3, characterized in that: The axis of the expansion cylinder (301) forms an angle of thirty degrees with the vertical direction, and the expansion cylinder (301) and the compression cylinder (201) form an angle of sixty degrees. The compression cylinder (201) and the expansion cylinder (301) are both connected to a servo electric push rod (104).

5. The low temperature refrigeration system for oil and gas liquefaction according to claim 4, characterized in that: The heat dissipation box (101) is connected to an air collecting hood (102), and the contour of the air collecting hood (102) matches the contour of the heat dissipation box (101). A heat dissipation fan (103) is arranged in the middle of the air collecting hood (102), and the arc outer wall of the heat dissipation fan (103) is tangent to the three long sides of the air collecting hood (102).

6. The low temperature refrigeration system for oil and gas liquefaction according to claim 5, characterized in that: The outer walls of the compression cylinder (201) and the expansion cylinder (301) are both fixedly connected to the air collecting hood (102) with a bracket (106), and the ends of the two brackets (106) are respectively fixedly sleeved on the compression cylinder (201) and the expansion cylinder (301), and the other end of the bracket (106) is in a plate shape and is fitted and fixedly connected to the outer wall of the air collecting hood (102).

7. The low temperature refrigeration system for oil and gas liquefaction according to claim 1, characterized in that: The port of the flow channel (302d) located on the bottom surface of the piston (302) is arranged on the edge of the piston (302), and the bottom surface of the piston (302) is coaxially fixedly connected with the push rod of the servo electric push rod (104) along its axial direction.

8. The low temperature refrigeration system for oil and gas liquefaction according to claim 4, characterized in that: An adapter seat (105) is also fixedly connected in series between the housing of the servo electric push rod (104) and the expansion cylinder (301), and a high-pressure hose connected to the discharge check valve (305) passes through the adapter seat (105).

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