Three-time oil gas recovery system based on pressurized condensation and low-temperature expansion

Abstract

The invention discloses a tertiary oil gas recovery system based on pressurized condensation and low-temperature expansion, and belongs to the technical field of oil gas recovery. Comprising a pre-cooling part, a compression part, a condensation and separation part and a low-temperature expansion and residual cold recovery part, wherein the pre-cooling part is used for pre-cooling an initial oil gas-air mixture; the compression part is used for compressing the pre-cooled oil gas-air mixture; the condensation and separation part is used for cooling the compressed oil-gas-air mixture, so that oil gas is liquefied, and gas-liquid separation is carried out; and the low-temperature expansion and residual cold recovery part is used for carrying out expansion refrigeration on the oil gas-air mixture which is not liquefied after pressurized condensation to generate cold energy, further liquefying the oil gas and carrying out residual cold recovery. Oil gas is liquefied by using a method of combining pressurized condensation and low-temperature expansion, a refrigerant is not needed, the energy consumption is lower than that of a cascade refrigeration system, the purposes of up-to-standard emission of gas and accurate recovery of oil can be achieved, and the system has the advantages of low complexity and considerable recovery rate.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas recovery, and more particularly to a tertiary oil and gas recovery system based on pressurized condensation and low-temperature expansion. Background Art

[0002] Oil and gas recovery technology is a technology that processes waste or gas emitted during production to recover valuable oil. In the fields of petroleum, chemical industry, metallurgy, environmental protection, etc., there is a demand for the recovery of oil in waste gas. Through oil and gas recovery technology, environmental pollution can be reduced, resource waste can be reduced, resource utilization can be improved, gas emission can meet standards, and oil can be accurately recovered, which has important economic and environmental benefits.

[0003] Among the current oil and gas recovery technologies, the main traditional recovery methods are adsorption, absorption, condensation and membrane separation. At present, the commonly used oil and gas recovery method in gas stations is the condensation-adsorption method. The basic process of the condensation-adsorption method is: the initial oil and gas-air mixture first enters the designed condensation module to condense and liquefy the oil and gas-air mixture, liquefy most of the oil and gas, and then a small amount of unliquefied oil and gas enters the adsorption device, and the oil and gas meet the national discharge standards through the adsorption device. The condensation method includes primary condensation, tertiary condensation and cascade refrigeration. The most widely used methods are the tertiary condensation method and the cascade refrigeration method. Although the tertiary condensation method and the cascade refrigeration method have high oil and gas recovery efficiency, they have high energy consumption and require multiple refrigerants. It can be seen that although the existing method can improve the oil and gas recovery rate, this method has the disadvantages of a relatively complex system, high energy consumption and the need for multiple refrigerants.

[0004] Therefore, how to provide a tertiary oil and gas recovery system based on pressurized condensation and low-temperature expansion to achieve accurate oil and gas separation and protect the environment is an urgent problem that technical personnel in this field need to solve. Summary of the invention

[0005] In view of this, the present invention provides a tertiary oil and gas recovery system based on pressurized condensation and low-temperature expansion, which uses a method combining pressurized condensation and low-temperature expansion to replace the existing oil and gas recovery technology, and uses a refrigerant-free method to reduce the energy consumption of the system, so as to solve the problems of refrigerant required and excessive energy consumption in the oil and gas recovery process, and achieve the purpose of gas emission meeting the standards and accurate oil recovery.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A tertiary oil and gas recovery system based on pressurized condensation and cryogenic expansion, comprising:

[0008] Pre-cooling section, compression section, condensation and separation section, low-temperature expansion and residual cooling recovery section;

[0009] Wherein, the precooling unit precools the initial oil-gas-air mixture;

[0010] The compression unit compresses the pre-cooled oil-gas-air mixture;

[0011] The condensation and separation part cools the compressed oil and gas to liquefy the oil and gas, and performs gas-liquid separation;

[0012] The low-temperature expansion and residual cold recovery unit expands and cools the oil-gas-air mixture that has not been liquefied after pressurization and condensation, generates cold energy, further liquefies the oil-gas, and recovers the residual cold.

[0013] Furthermore, the precooling unit is a first heat exchanger L1, which precools the initial oil-gas-air mixture.

[0014] Further, the compression unit includes: a first-stage compressor K1 and a second-stage compressor K2;

[0015] The first stage compressor K1 compresses the pre-cooled oil-gas-air mixture, and the second stage compressor K2 further compresses the remaining oil-gas-air mixture.

[0016] Further, the condensation and separation part includes: a first heat exchanger E1, a second heat exchanger E2, a first gas-liquid separator F1 and a second gas-liquid separator F2;

[0017] Among them, the first heat exchanger E1 cools the oil and gas compressed by the first-stage compressor K1 to liquefy the water vapor and oil and gas; the second heat exchanger E2 cools the oil and gas compressed by the second-stage compressor K2 to liquefy the water vapor and oil and gas; the first gas-liquid separator F1 separates the water and oil and gas liquefied after condensation by the first heat exchanger E1 from the oil and gas-air mixture that is not liquefied after condensation by the first heat exchanger E1; the second gas-liquid separator F2 separates the water and oil and gas liquefied after condensation by the second heat exchanger E2 from the oil and gas-air mixture that is not liquefied after condensation by the second heat exchanger E2 to obtain a separated oil and gas-air mixture.

[0018] Furthermore, the low-temperature expansion and residual cold recovery unit includes: a second heat exchanger L2, an expander K3, a third gas-liquid separator F3 and a fourth gas-liquid separator F4;

[0019] The low temperature expansion and residual cold recovery unit includes: a second heat exchanger L2, an expander K3, a third gas-liquid separator F3 and a fourth gas-liquid separator F4;

[0020] Among them, the second heat exchanger L2 cools the oil-gas-air mixture separated by the second gas-liquid separator F2; the third gas-liquid separator F3 separates the oil and gas liquefied after heat exchange in the second heat exchanger L2 from the oil-gas-air mixture not liquefied after heat exchange in the second heat exchanger L2; the expander K3 expands and cools the oil-gas-air mixture separated by the third gas-liquid separator F3 to generate cold energy and recover the remaining oil and gas; the fourth gas-liquid separator F4 separates the oil and gas liquefied after expansion by the expander K3 from the low-temperature oil-gas-air mixture not liquefied after expansion by the expander K3 to obtain a first oil-gas-air mixture, the first oil-gas-air mixture and the separated oil-gas-air mixture are heat exchanged in the second heat exchanger L2 to obtain a second oil-gas-air mixture, the second oil-gas-air mixture is heat exchanged with the initial oil-gas-air mixture in the first heat exchanger L1 to pre-cool the initial oil-gas-air mixture and complete the recovery of residual cold.

[0021] It can be seen from the above technical scheme that, compared with the prior art, the present invention discloses a tertiary oil and gas recovery system based on pressurized condensation and low-temperature expansion, which uses a method combining pressurized condensation and low-temperature expansion to replace the existing oil and gas recovery technology, and uses a refrigerant-free method to reduce the energy consumption of the system and reduce pollution to the atmosphere, so as to solve the problems of refrigerant required and excessive energy consumption in the oil and gas recovery process. The system is not complex and has the advantage of a considerable recovery rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0023] Figure 1 It is a schematic diagram of the system process flow of the present invention. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] The purpose of the present invention is to provide a tertiary oil and gas recovery system based on pressurized condensation and low-temperature expansion, comprising: a precooling section, a compression section, a condensation and separation section, a low-temperature expansion and residual cold recovery section; wherein the precooling section precools the initial oil and gas-air mixture; the compression section compresses the precooled oil and gas-air mixture; the condensation and separation section cools the compressed oil and gas-air mixture to liquefy the oil and gas, and performs gas-liquid separation; in the low-temperature expansion and residual cold recovery section, the low-temperature expansion performs expansion and refrigeration on the oil and gas-air mixture that has not been liquefied after pressurized condensation, generates cold, and performs residual cold recovery. The present invention uses a method combining pressurized condensation and low-temperature expansion to liquefy the oil and gas. The system provided by the present invention does not require refrigerant and consumes less energy than a cascade refrigeration system. It has the advantages of low system complexity and considerable recovery rate.

[0026] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] The embodiment of the present invention discloses a tertiary oil and gas recovery system based on pressurized condensation and low-temperature expansion, comprising:

[0028] Pre-cooling section, compression section, condensation and separation section, low-temperature expansion and residual cooling recovery section;

[0029] Among them, the pre-cooling part pre-cools the initial oil-gas-air mixture;

[0030] The compression section compresses the pre-cooled oil-gas-air mixture;

[0031] The condensation and separation section cools the compressed oil and gas, liquefies the oil and gas, and separates the gas and liquid;

[0032] The low-temperature expansion and residual cold recovery section expands and refrigerates the oil, gas and air mixture that has not been liquefied after pressurization and condensation, generates cold energy, further liquefies the oil and gas, and recovers the residual cold.

[0033] In a specific embodiment, the so-called oil and gas recovery refers to a complete oil and gas recovery system consisting of three stages: primary recovery, secondary recovery and tertiary recovery. In the primary recovery stage, when the tanker truck unloads oil into the underground oil storage tank, the oil and gas in the oil storage tank are recovered into the tanker truck; in the secondary recovery stage, when the gas pump dispenses oil, the vacuum pump recovers the oil and gas in the car tank into the underground oil storage tank. These two stages are mainly the process of collecting oil and gas. The tertiary recovery stage converts the collected oil and gas from gas to liquid through adsorption or condensation and other methods so that it can be reused. The technical means of the present invention belongs to the tertiary recovery stage.

[0034] Specifically, because the oil and gas recovery rate of the booster condensing system does not meet the national recovery standards, a low-temperature expansion system is added, and most of the oil and gas is recovered in the booster condensing system.

[0035] In a specific embodiment, the precooling unit is a first heat exchanger L1, which precools the initial oil-gas-air mixture.

[0036] In a specific embodiment, the compression unit includes: a first-stage compressor K1 and a second-stage compressor K2;

[0037] The first-stage compressor K1 compresses the pre-cooled oil-gas-air mixture, and the second-stage compressor K2 further compresses the remaining oil-gas-air mixture. Specifically, the so-called further compressing the remaining oil-gas-air mixture refers to compressing the oil-gas-air mixture separated by the first separator F1.

[0038] In a specific embodiment, the condensation and separation part includes: a first heat exchanger E1, a second heat exchanger E2, a first gas-liquid separator F1 and a second gas-liquid separator F2;

[0039] Among them, the first heat exchanger E1 cools the oil and gas compressed by the first-stage compressor K1 to liquefy the water vapor and oil and gas (after the first condensation, most of the water vapor is liquefied, and a small part of the oil and gas is liquefied); the second heat exchanger E2 cools the oil and gas compressed by the second-stage compressor K2 to liquefy the water vapor and oil and gas; the first gas-liquid separator F1 separates the water and oil and gas liquefied after condensation by the first heat exchanger E1 from the oil and gas-air mixture that is not liquefied after condensation by the first heat exchanger E1; the second gas-liquid separator F2 separates the water and oil and gas liquefied after condensation by the second heat exchanger E2 from the oil and gas-air mixture that is not liquefied after condensation by the second heat exchanger E2 to obtain a separated oil and gas-air mixture, wherein the separated oil and gas-air mixture is the oil and gas-air mixture that is not liquefied after condensation by the second heat exchanger E2 separated by the second gas-liquid separator F2, that is, the oil and gas-air mixture that is not liquefied after pressurized condensation.

[0040] In a specific embodiment, the low temperature expansion and residual cold recovery unit includes: a second heat exchanger L2, an expander K3, a third gas-liquid separator F3 and a fourth gas-liquid separator F4;

[0041] Among them, the second heat exchanger L2 cools the oil-gas-air mixture separated by the second gas-liquid separator F2 to prepare for subsequent low-temperature expansion; the third gas-liquid separator F3 separates the liquefied oil and gas after heat exchange by the second heat exchanger L2 from the oil-gas-air mixture that is not liquefied after heat exchange by the second heat exchanger L2; the expander K3 expands and cools the oil-gas-air mixture separated by the third gas-liquid separator F3 to generate cold energy and recover the remaining oil and gas; the fourth gas-liquid separator F4 separates the liquefied oil and gas after expansion by the expander K3 from the low-temperature oil-gas-air mixture that is not liquefied after expansion by the expander K3 to obtain the first oil-gas-air mixture The low-temperature oil-gas-air mixture that is not liquefied after expansion by the fourth gas-liquid separator F4 is separated by the expander K3 is called the first oil-gas-air mixture; the first oil-gas-air mixture and the separated oil-gas-air mixture (i.e., the oil-gas-air mixture that is not liquefied after pressurization and condensation) are heat exchanged in the second heat exchanger L2 to obtain a second oil-gas-air mixture, wherein the second oil-gas-air mixture is the first oil-gas-air mixture after heat exchange, and the second oil-gas-air mixture and the initial oil-gas-air mixture are heat exchanged in the first heat exchanger L1 to pre-cool the initial oil-gas-air mixture and complete the waste cold recovery.

[0042] Specifically, the low-temperature expansion and waste cold recovery unit mainly includes the second heat exchanger L2, the expander K3, the third gas-liquid separator F3 and the fourth gas-liquid separator F4, which work together to achieve effective recovery of oil and gas and efficient utilization of energy. The reason for the existence of the low-temperature expansion system is that the recovery rate of oil and gas in the boost condensation system is not enough to meet the national recovery rate standard, so the low-temperature expansion system is introduced to recover the energy of high-pressure oil and gas. Providing cold capacity is the key to the low-temperature expansion system to achieve efficient oil and gas recovery and energy utilization. By reducing the temperature and pressure of the oil and gas mixture and recovering the energy therein, the low-temperature expansion system can further improve the recovery rate of oil and gas, optimize system performance, reduce operating costs and reduce environmental pollution. Therefore, in the field of oil and gas recovery, the low-temperature expansion system has broad application prospects and important environmental and economic value.

[0043] See also Figure 1 , is a process flow chart of the present invention. The present invention provides a tertiary oil and gas recovery system based on pressurized condensation and low-temperature expansion, and the specific process is as follows:

[0044] The initial oil-gas-air mixture enters the first heat exchanger L1 from V1 to pre-cool the oil and gas, and the cooling capacity is provided by B7. The pre-cooled oil-gas-air mixture enters the first compressor K1 through V2. The oil-gas-air mixture after the first stage compression enters the first heat exchanger E1 through V3 for cooling. After cooling, it enters the first gas-liquid separator F1 through V4. At this time, most of the water vapor and part of the oil and gas are liquefied. The oil-gas-air mixture that has not been liquefied through the first heat exchanger E1 enters the second compressor K2 through V5 after passing through the first gas-liquid separator F1. The oil-gas-air mixture after the second stage compression enters the second heat exchanger E2 through V7 for cooling. After cooling, it enters the second gas-liquid separator F2 through V8. At this time, most of the oil and gas have been liquefied, completing the supercharging and condensing stage. The liquid oil flows out from V6 and V10 for collection. The unliquefied oil-gas-air mixture after supercharging and condensing enters the second heat exchanger L2 through V9 for cooling, and enters the third gas-liquid separator F3 through B1 after cooling. The oil-gas-air mixture separated by the third gas-liquid separator F3 enters the expander K3 through B2 for expansion and refrigeration, and enters the fourth gas-liquid separator F4 through B4 after expansion to separate the low-temperature expanded liquid oil and the low-temperature oil-gas-air mixture. The low-temperature oil-gas-air mixture separated by the fourth gas-liquid separator F4 passes through B5 and the unliquefied oil-gas-air mixture after supercharging and condensing, and passes through V9 to exchange heat in the second heat exchanger L2. The low-temperature oil-gas-air mixture separated by the fourth gas-liquid separator F4 after heat exchange passes through B7 in the first heat exchanger L1 to pre-cool the initial oil-gas-air mixture at the inlet, and is finally discharged through B8, completing the low-temperature expansion process and the residual cold recovery process, and the liquid oil flows out from B3 and B6 for collection.

[0045] Specifically, Q1 and Q3 are the work consumed by the compressor; Q2 and Q4 are the heat exchange amounts of the heat exchanger; and Q5 is the work output by the expander.

[0046] Specifically, the present invention mainly aims at liquefying and recovering oil and gas in gas stations, and uses a method combining pressurized condensation and low-temperature expansion to liquefy oil and gas. The present invention provides a tertiary oil and gas recovery system based on pressurized condensation and low-temperature expansion, which does not require refrigerant and consumes less energy than a cascade refrigeration system. Compared with the prior art, the present invention does not require refrigerant and has lower energy consumption, and has the advantages of low system complexity and considerable recovery rate.

[0047] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0048] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A tertiary oil and gas recovery system based on pressurized condensation and low-temperature expansion, characterized in that: include: Pre-cooling section, compression section, condensation and separation section, low-temperature expansion and residual cooling recovery section; Wherein, the precooling unit precools the initial oil-gas-air mixture; The compression unit compresses the pre-cooled oil-gas-air mixture; The condensation and separation part cools the compressed oil and gas to liquefy the oil and gas, and performs gas-liquid separation; The low-temperature expansion and residual cold recovery unit expands and cools the oil-gas-air mixture that has not been liquefied after pressurization and condensation, generates cold energy, further liquefies the oil-gas, and recovers the residual cold.

2. A tertiary oil and gas recovery system based on pressurized condensation and low-temperature expansion according to claim 1, characterized in that: The pre-cooling unit is a first heat exchanger L1, which pre-cools the initial oil-gas-air mixture.

3. The tertiary oil and gas recovery system based on pressurized condensation and low-temperature expansion according to claim 1 is characterized in that: The compression unit includes: a first-stage compressor K1 and a second-stage compressor K2; The first stage compressor K1 compresses the pre-cooled oil-gas-air mixture, and the second stage compressor K2 further compresses the remaining oil-gas-air mixture.

4. The tertiary oil and gas recovery system based on pressurized condensation and low-temperature expansion according to claim 3 is characterized in that: The condensation and separation part includes: a first heat exchanger E1, a second heat exchanger E2, a first gas-liquid separator F1 and a second gas-liquid separator F2; Among them, the first heat exchanger E1 cools the oil and gas compressed by the first-stage compressor K1 to liquefy the water vapor and oil and gas; the second heat exchanger E2 cools the oil and gas compressed by the second-stage compressor K2 to liquefy the water vapor and oil and gas; the first gas-liquid separator F1 separates the water and oil and gas liquefied after condensation by the first heat exchanger E1 from the oil and gas-air mixture that is not liquefied after condensation by the first heat exchanger E1; the second gas-liquid separator F2 separates the water and oil and gas liquefied after condensation by the second heat exchanger E2 from the oil and gas-air mixture that is not liquefied after condensation by the second heat exchanger E2 to obtain a separated oil and gas-air mixture.

5. The tertiary oil and gas recovery system based on pressurized condensation and low-temperature expansion according to claim 4 is characterized in that: The low temperature expansion and residual cold recovery unit includes: a second heat exchanger L2, an expander K3, a third gas-liquid separator F3 and a fourth gas-liquid separator F4; Among them, the second heat exchanger L2 cools the oil-gas-air mixture separated by the second gas-liquid separator F2; the third gas-liquid separator F3 separates the oil and gas liquefied after heat exchange in the second heat exchanger L2 from the oil-gas-air mixture not liquefied after heat exchange in the second heat exchanger L2; the expander K3 expands and cools the oil-gas-air mixture separated by the third gas-liquid separator F3 to generate cold energy and recover the remaining oil and gas; the fourth gas-liquid separator F4 separates the oil and gas liquefied after expansion by the expander K3 from the low-temperature oil-gas-air mixture not liquefied after expansion by the expander K3 to obtain a first oil-gas-air mixture, the first oil-gas-air mixture and the separated oil-gas-air mixture are heat exchanged in the second heat exchanger L2 to obtain a second oil-gas-air mixture, the second oil-gas-air mixture is heat exchanged with the initial oil-gas-air mixture in the first heat exchanger L1 to pre-cool the initial oil-gas-air mixture and complete the recovery of residual cold.

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