Process method for preparing LNG based on high-pressure natural gas differential pressure of underground gas storage

Abstract

The application discloses a kind of process methods for preparing LNG based on high-pressure natural gas differential pressure of underground gas storage, applied to oil and gas preparation technical field, the natural gas of underground gas storage is preliminarily purified, and cooling is carried out.By primary jet pump processing, gas-liquid phase mixture is obtained.After execution of rewarming operation by primary separator, gas separation of medium-pressure gas after rewarming is executed, decarburization purification is completed, and cooling is carried out.Gas-liquid mixed gas is obtained, and input into secondary separator.The low-pressure liquid at the bottom of secondary separator is throttled by regulating valve and then enters into fourth-stage separator, the liquid output at the bottom is stored as LNG product, and the gas output at the top enters into secondary jet pump for recycling.Circulating cold source supply rule is set, by-product is collected, and cold source supply for product preparation process is carried out based on by-product.The technical problems of high temperature regulation energy consumption and high-pressure natural gas pressure difference energy waste during underground gas storage high-pressure natural gas export in prior art are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil and gas production, and particularly relates to a process method for preparing LNG based on high-pressure natural gas differential pressure of underground gas storage. BACKGROUND

[0002] The underground gas storage, as an important natural gas emergency peak shaving storage facility in China, plays an important role in the safety guarantee of urban gas supply and has become an important part of the integrated utilization of the upstream and downstream of natural gas in China. The storage pressure of the underground gas storage is generally 20.0 MPa, and the pressure of the downstream medium-pressure gas supply pipeline is generally 4.0 MPa to 5.0 MPa. At present, the high-pressure natural gas of the underground gas storage is reduced in pressure and temperature through a regulating valve, and the low-temperature natural gas needs to be heated by a matched electric heater, so as to control the temperature of the medium-pressure external natural gas. The process has the disadvantages of not only consuming power consumption and increasing the operation cost of pressure boosting, but also causing the waste of pressure differential energy of the high-pressure natural gas.

[0003] Therefore, in the prior art, there are the technical problems of high energy consumption of temperature regulation and waste of pressure differential energy of high-pressure natural gas when the high-pressure natural gas of the underground gas storage is externally transported. SUMMARY

[0004] The present application provides a process method for preparing LNG based on high-pressure natural gas differential pressure of underground gas storage, which solves the technical problems of high energy consumption of temperature regulation and waste of pressure differential energy of high-pressure natural gas when the high-pressure natural gas of the underground gas storage is externally transported in the prior art.

[0005] The application provides a process method for preparing LNG based on high-pressure natural gas differential pressure of underground gas storage, which comprises the following steps: sequentially inputting natural gas of underground gas storage into a dehydration adsorption tower, a mercury removal tower and a dust filter arranged in parallel to complete preliminary purification; inputting the natural gas after preliminary purification into a high-pressure pre-cooling heat exchanger, a high-pressure main cooling heat exchanger and a high-pressure super-cooling heat exchanger to cool; treating the natural gas after cooling by a first jet pump to obtain a gas-liquid phase mixture, and inputting the gas-liquid phase mixture into a first separator; performing a rewarming operation on the separated gas of the first separator, and performing gas separation on the medium-pressure gas after rewarming, and then performing decarburization purification on the target separated gas after pressurization; sequentially cooling the target separated gas after decarburization purification by a medium-pressure pre-cooling heat exchanger and a medium-pressure main cooling heat exchanger; treating the target separated gas after cooling by a second jet pump to obtain a gas-liquid mixture, and inputting the gas-liquid mixture into a second separator; throttling the low-pressure liquid output from the bottom of the second separator by an adjusting valve to enter a fourth separator, and storing the liquid output from the bottom of the fourth separator as LNG products, and inputting the gas output from the top of the fourth separator into a second jet pump to recycle; setting a circulating cold source supply rule, collecting by-products of the first separator, the medium-pressure pre-cooling heat exchanger, the high-pressure main cooling heat exchanger and a third separator based on the circulating cold source supply rule, and supplying a cold source for the process of preparing the LNG products based on the by-products.

[0006] The application also provides a process system for preparing LNG by differential pressure of high-pressure natural gas based on underground gas storage, which comprises: a preliminary purification module, which is used for sequentially inputting natural gas from underground gas storage into a dehydration adsorption tower, a mercury removal tower and a dust filter arranged in parallel to complete preliminary purification; a high-pressure cooling module, which is used for inputting the natural gas after preliminary purification into a high-pressure pre-cooling heat exchanger, a high-pressure main cooling heat exchanger and a high-pressure super-cooling heat exchanger to perform cooling; a gas-liquid phase mixture obtaining module, which is used for treating the natural gas after cooling by a first jet pump to obtain a gas-liquid phase mixture and inputting the gas-liquid phase mixture into a first separator; a decarburization purification module, which is used for performing rewarming operation on separated gas from the first separator and performing gas separation on medium-pressure gas after rewarming to perform decarburization purification on target separated gas after pressurization; a medium-pressure cooling module, which is used for sequentially inputting the target separated gas after decarburization purification into a medium-pressure pre-cooling heat exchanger and a medium-pressure main cooling heat exchanger to perform cooling; a gas-liquid mixture obtaining module, which is used for treating the target separated gas after cooling by a second jet pump to obtain a gas-liquid mixture and inputting the gas-liquid mixture into a second separator; a recycling module, which is used for inputting low-pressure liquid output from the bottom of the second separator into a fourth separator after throttling by an adjusting valve, storing liquid output from the bottom of the fourth separator as LNG product, and inputting gas output from the top of the fourth separator into the second jet pump to perform recycling; and a cold source supply module, which is used for setting a circulating cold source supply rule, collecting by-products of the first separator, the medium-pressure pre-cooling heat exchanger, the high-pressure main cooling heat exchanger and a third separator based on the circulating cold source supply rule, and supplying cold source for preparing the LNG product based on the by-products.

[0007] The application also provides an electronic device, comprising:

[0008] a memory configured to store executable instructions;

[0009] a processor configured to execute the executable instructions stored in the memory to implement the process method for preparing LNG by differential pressure of high-pressure natural gas based on underground gas storage.

[0010] The application provides a computer readable storage medium storing a computer program, which is executed by a processor to implement the process method for preparing LNG by differential pressure of high-pressure natural gas based on underground gas storage.

[0011] A process method for preparing LNG by differential pressure of high-pressure natural gas based on underground gas storage is provided in the present application. The natural gas in the underground gas storage is preliminarily purified and cooled. A gas-liquid mixture is obtained by a first-stage jet pump. After separation by a first-stage separator, a re-heating operation is performed, and after re-heating, the gas separation of medium-pressure gas is performed, the decarburization purification is completed, and the cooling is performed. The gas-liquid mixture is obtained and input into a second-stage separator. The low-pressure liquid at the bottom of the second-stage separator is throttled by an adjusting valve and then input into a fourth-stage separator. The liquid output at the bottom is stored as LNG product, and the gas output at the top is input into a second-stage jet pump for recycling. A circulating cold source supply rule is set, the by-products are collected, and the cold source supply for the product preparation process is performed based on the by-products. The recycling of regenerated gas is realized. The high-pressure natural gas is jetted by a first-stage jet pump to reduce the pressure, the medium-pressure external natural gas and the cold energy required for cooling the medium-pressure natural gas are obtained, the temperature regulation energy consumption during the external transmission of the high-pressure natural gas in the underground gas storage is reduced, and the pressure difference energy waste of the high-pressure natural gas is avoided. The technical problems of high temperature regulation energy consumption and high-pressure natural gas pressure difference energy waste during the external transmission of the high-pressure natural gas in the underground gas storage in the prior art are solved.

[0012] The above description is only a summary of the technical scheme of the present application. In order to more clearly understand the technical means of the present application, the specific embodiments of the present application can be implemented according to the content of the description, and in order to make the above and other purposes, characteristics and advantages of the present application more obvious and easy to understand, the following will specifically describe the embodiments of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0013] In order to more clearly illustrate the technical scheme of the embodiments of the present disclosure, the drawings of the embodiments of the present disclosure will be briefly introduced below. Obviously, the drawings described below only relate to some embodiments of the present disclosure, but not limit the present disclosure.

[0014] Figure 1 A flowchart of a process method for preparing LNG by differential pressure of high-pressure natural gas based on underground gas storage according to the present application;

[0015] Figure 2 A flowchart of a process method for preparing LNG by differential pressure of high-pressure natural gas based on underground gas storage according to the present application, in which the target separated gas is pressurized and then decarburized and purified;

[0016] Figure 3 A structure schematic diagram of a system of a multi-device joint operation control method of power equipment provided by an embodiment of the present application;

[0017] Figure 4 A structure schematic diagram of a system electronic device of a multi-device joint operation control method of power equipment provided by an embodiment of the present application.

[0018] Reference signs: preliminary purification module 11, high-pressure cooling module 12, gas-liquid mixture obtaining module 13, decarburization purification module 14, medium-pressure cooling module 15, gas-liquid mixture obtaining module 16, recycling module 17, cold source supply module 18, processor 31, memory 32, input device 33, output device 34. DETAILED DESCRIPTION

[0019] Embodiment one

[0020] In order to make the purposes, technical solutions and advantages of the present application clearer, the present application will be described in further detail below with reference to the drawings, and the described embodiments should not be regarded as limiting the present application, and all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present application.

[0021] In the following description, "some embodiments" are referred to, which describe a subset of all possible embodiments, but it can be understood that "some embodiments" can be the same subset or different subsets of all possible embodiments, and can be combined with each other without conflict.

[0022] In the following description, the terms "first\second\third" are only to distinguish similar objects, and do not represent a specific order of the objects, and it can be understood that "first\second\third" can be interchanged in a specific order or sequence as allowed, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terms used herein are only for the purpose of describing the embodiments of the present application.

[0024] Although the present application makes various references to certain modules in the system according to the embodiments of the present application, however, any number of different modules can be used and run on the user terminal and / or server, the modules are only illustrative, and different aspects of the system and method can use different modules.

[0025] Flowcharts are used in the present application to illustrate the operations performed by the system according to the embodiments of the present application. It should be understood that the preceding or following operations are not necessarily performed in sequence. On the contrary, various steps can be processed in reverse order or simultaneously as needed. Meanwhile, other operations can be added to these processes, or one or more steps of operations can be removed from these processes.

[0026] As Figure 1As shown, the embodiment of the present application provides a process method for preparing LNG based on underground gas storage high-pressure natural gas differential pressure, which comprises the following steps:

[0027] S10: sequentially inputting the natural gas of the underground gas storage into the dehydration adsorption tower, the mercury removal tower and the dust filter arranged in parallel to complete preliminary purification;

[0028] S20: inputting the natural gas after preliminary purification into the high-pressure pre-cooling heat exchanger, the high-pressure main cooling heat exchanger and the high-pressure super-cooling heat exchanger to cool;

[0029] S30: treating the natural gas after cooling by the first jet pump to obtain a gas-liquid phase mixture, and inputting the gas-liquid phase mixture into the first separator;

[0030] S40: performing a rewarming operation on the separated gas of the first separator, and performing gas separation on the medium-pressure gas after rewarming, and performing decarburization purification on the target separated gas after pressurization;

[0031] Specifically, the underground gas storage is an important natural gas emergency peak shaving storage facility in China, and plays an important role in urban gas safety guarantee, and has become an important part of the integrated utilization of the upstream and downstream of natural gas in China. The storage pressure of the underground gas storage is generally 20.0 MPa, and the pressure of the downstream medium-pressure gas supply pipeline is generally 4.0 MPa-5.0 MPa. At present, the high-pressure natural gas of the underground gas storage is cooled and depressurized by the regulating valve, and the low-temperature natural gas needs to be heated by the electric heater, and then the temperature of the medium-pressure external natural gas is controlled. The disadvantage of this process is not only the consumption of power consumption and the increase of pressurization operation cost, but also the waste of pressure differential energy of high-pressure natural gas. In order to utilize the residual pressure energy of the underground gas storage external natural gas and reduce the power load of the electric heater, the natural gas of the underground gas storage is sequentially inputted into the dehydration adsorption tower, the mercury removal tower and the dust filter arranged in parallel to complete preliminary purification. The natural gas after preliminary purification is inputted into the high-pressure pre-cooling heat exchanger, the high-pressure main cooling heat exchanger and the high-pressure super-cooling heat exchanger to cool. The natural gas after cooling is treated by the first jet pump to obtain a gas-liquid phase mixture, and the gas-liquid phase mixture is inputted into the first separator. The separated gas of the first separator is subjected to a rewarming operation, and the gas from the top of the first separator is subjected to rewarming by the high-pressure super-cooling heat exchanger, the high-pressure main cooling heat exchanger and the high-pressure pre-cooling heat exchanger. The medium-pressure gas after rewarming is divided into two shares, one share is used for external transmission through the medium-pressure pipeline network, and the other share is pressurized by the raw gas compressor and then subjected to deep decarburization purification by the decarburization adsorption tower and the dust filter. The target separated gas after pressurization is subjected to decarburization purification.

[0032] The method S10 provided by the embodiment of the present application further comprises the following steps:

[0033] S11: extracting the natural gas to generate regeneration gas before inputting into the dehydration adsorption tower;

[0034] S12: cooling and purging the regeneration gas through the dehydration adsorption tower and heating by a regeneration gas heater;

[0035] S13: inputting the heated regeneration gas into the dehydration adsorption tower to heat and regenerate the adsorbent in the dehydration adsorption tower;

[0036] S14: after completing the regeneration of the adsorbent, performing predetermined treatment on the regeneration gas, and inputting the treatment result into the dehydration adsorption tower after mixing with the natural gas.

[0037] Specifically, before inputting the natural gas from the underground gas storage into the dehydration adsorption tower, the natural gas is extracted to generate regeneration gas, that is, a part of the natural gas is separated to regenerate the adsorbent in the adsorption tower. The regeneration gas is cooled and purged through the dehydration adsorption tower and heated by a regeneration gas heater, that is, the regeneration gas enters the adsorption tower that needs to be cooled through a process control valve to be cooled and purged, and the purged regeneration gas enters the regeneration gas heater to be heated. The heated regeneration gas is input into the dehydration adsorption tower to heat and regenerate the adsorbent in the dehydration adsorption tower. After completing the regeneration of the adsorbent, the regeneration gas is subjected to predetermined treatment, and the treatment result is input into the dehydration adsorption tower after mixing with the natural gas.

[0038] The method S14 provided by the embodiment of the present application further comprises:

[0039] S141: inputting the regeneration gas into a cooler to be cooled, and pre-cooling the cooled regeneration gas through a heat exchanger;

[0040] S142: supercooling the pre-cooled regeneration gas through a cold gas unit, and then separating free water through a dehydration separator;

[0041] S143: mixing the regeneration gas output from the dehydration separator with the natural gas after heat exchanger rewarming, and inputting into the dehydration adsorption tower.

[0042] Specifically, the predetermined treatment on the regeneration gas comprises inputting the regeneration gas into a cooler to be cooled, and pre-cooling the cooled regeneration gas through a heat exchanger. The pre-cooled regeneration gas is supercooled through a cold gas unit, and then separated from free water through a dehydration separator. Finally, the regeneration gas output from the dehydration separator is mixed with the natural gas after heat exchanger rewarming, and input into the dehydration adsorption tower.

[0043] S50: sequentially cooling and cooling the target separation gas after completing decarburization purification through a medium-pressure pre-cooling heat exchanger and a medium-pressure main cooling heat exchanger;

[0044] S60: treating the target separation gas after temperature reduction and cooling by a secondary ejector pump, obtaining gas-liquid mixed gas, and inputting the gas-liquid mixed gas into a secondary separator;

[0045] S70: throttling the low-pressure liquid output from the bottom of the secondary separator by an adjusting valve and then inputting the low-pressure liquid into a fourth separator, storing the liquid output from the bottom of the fourth separator as LNG products, and inputting the gas output from the top of the fourth separator into the secondary ejector pump for recycling and recovery;

[0046] S80: setting a circulating cold source supply rule, collecting by-products of the primary separator, the medium-pressure pre-cooling heat exchanger, the high-pressure main cooling heat exchanger, and the third separator based on the circulating cold source supply rule, and supplying a cold source for the preparation of the LNG products based on the by-products.

[0047] Specifically, the target separation gas after decarburization and purification is sequentially subjected to temperature reduction and cooling by a medium-pressure pre-cooling heat exchanger and a medium-pressure main cooling heat exchanger. The target separation gas after temperature reduction and cooling is treated by a secondary ejector pump to obtain gas-liquid mixed gas, and the gas-liquid mixed gas is input into a secondary separator. The low-pressure gas output from the top of the secondary separator is subjected to temperature recovery by a medium-pressure main cooling heat exchanger, and then input into a high-pressure super-cooling heat exchanger and a high-pressure pre-cooling heat exchanger for temperature recovery. The low-pressure gas after temperature recovery is compressed to medium pressure by a compressor and then output to a medium-pressure pipeline. The low-pressure liquid output from the bottom of the secondary separator is throttled by an adjusting valve and then input into a fourth separator. The liquid output from the bottom of the fourth separator is stored as LNG products. The gas output from the top of the fourth separator is input into the secondary ejector pump for recycling and recovery.

[0048] The circulating cold source supply rule is set, and the by-products of the primary separator, the medium-pressure pre-cooling heat exchanger, the high-pressure main cooling heat exchanger and the three-stage separator are collected based on the circulating cold source supply rule, and the cold source supply of the LNG product preparation process is performed based on the by-products. Specifically, the medium-pressure liquid from the bottom of the primary separator becomes a low-pressure gas-liquid mixture through an adjusting valve, and then enters the medium-pressure pre-cooling heat exchanger to provide cold source for medium-pressure natural gas pre-cooling; the low-pressure gas-liquid mixture from the medium-pressure pre-cooling heat exchanger enters the high-pressure main cooling heat exchanger return flow channel to provide cold source for high-pressure natural gas cooling; the low-pressure gas-liquid mixture from the high-pressure main cooling heat exchanger enters the three-stage separator, and the low-pressure liquid from the bottom of the three-stage separator is mixed with the low-pressure gas from the return flow channel of the medium-pressure main cooling heat exchanger, and returns to the high-pressure sub-cooling heat exchanger and the high-pressure pre-cooling heat exchanger return flow channel to provide cold source for high-pressure natural gas cooling; the gas from the top of the three-stage separator enters the primary ejector pump for recycling. The recycling of the regenerated gas is realized, the high-pressure natural gas is jetted by the primary ejector pump to reduce the pressure, the medium-pressure external natural gas and the cold energy required for the cooling of the medium-pressure natural gas are obtained, the energy consumption for temperature adjustment of the high-pressure natural gas during external transmission of the underground gas storage is reduced, and the waste of pressure difference energy of the high-pressure natural gas is avoided.

[0049] The method S60 provided in the embodiment of the application further includes:

[0050] S61: obtaining non-target separated gas in the primary separator;

[0051] S62: warming the low-pressure gas output from the top of the secondary separator through the medium-pressure main cooling heat exchanger, the high-pressure sub-cooling heat exchanger and the high-pressure pre-cooling heat exchanger return flow channel, and pressurizing the warmed low-pressure gas to medium pressure through a BOG compressor;

[0052] S63: externally transmitting the non-target separated gas and the pressurized low-pressure gas through the medium-pressure pipeline.

[0053] Specifically, the non-target separated gas in the primary separator is obtained. The low-pressure gas output from the top of the secondary separator is warmed through the medium-pressure main cooling heat exchanger, the high-pressure sub-cooling heat exchanger and the high-pressure pre-cooling heat exchanger return flow channel, and the warmed low-pressure gas is pressurized to medium pressure through a BOG compressor. The non-target separated gas and the pressurized low-pressure gas are externally transmitted through the medium-pressure pipeline.

[0054] The method S80 provided in the embodiment of the application further includes:

[0055] S81: collecting the output medium-pressure liquid from the bottom of the primary separator, and adjusting the medium-pressure liquid to a low-pressure gas-liquid mixture through an adjusting valve;

[0056] S82: input the low-pressure gas-liquid mixture into the medium-pressure pre-cooling heat exchanger as a cold source of the medium-pressure pre-cooling heat exchanger;

[0057] S83: collect the first low-pressure gas-liquid mixture output by the medium-pressure pre-cooling heat exchanger, and input the first low-pressure gas-liquid mixture into a return flow channel of the high-pressure main cooling heat exchanger as a cold source of the high-pressure main cooling heat exchanger;

[0058] S84: collect the second low-pressure gas-liquid mixture output by the high-pressure main cooling heat exchanger, input the second low-pressure gas-liquid mixture into a three-stage separator, and mix the output low-pressure liquid with the low-pressure gas in the return flow channel of the medium-pressure main cooling heat exchanger;

[0059] S85: use the mixing result as a cold source of the high-pressure super-cooling heat exchanger and the high-pressure pre-cooling heat exchanger.

[0060] Specifically, the output medium-pressure liquid at the bottom of the first-stage separator is adjusted into a low-pressure gas-liquid mixture through an adjusting valve. The low-pressure gas-liquid mixture is input into the medium-pressure pre-cooling heat exchanger as a cold source of the medium-pressure pre-cooling heat exchanger. The first low-pressure gas-liquid mixture output by the medium-pressure pre-cooling heat exchanger is input into the return flow channel of the high-pressure main cooling heat exchanger as a cold source of the high-pressure main cooling heat exchanger. The second low-pressure gas-liquid mixture output by the high-pressure main cooling heat exchanger is input into a three-stage separator, and the output low-pressure liquid is mixed with the low-pressure gas in the return flow channel of the medium-pressure main cooling heat exchanger. The mixing result is used as a cold source of the high-pressure super-cooling heat exchanger and the high-pressure pre-cooling heat exchanger.

[0061] As shown in FIG. 4, Figure 2 the method S40 provided by the embodiment of the present application further includes:

[0062] S41: extract the target separated gas to construct medium-pressure regenerated gas, and adjust the pressure of the medium-pressure regenerated gas to the pressure level 4.0 MPa-5.0 MPa of the medium-pressure external pipeline through an adjusting valve;

[0063] S42: heat the medium-pressure regenerated gas through a process control valve and input the medium-pressure regenerated gas into a heater;

[0064] S43: input the heated medium-pressure regenerated gas into a desorption adsorption tower to heat and regenerate the adsorbent;

[0065] S44: after cooling, input the heated medium-pressure regenerated gas into a medium-pressure natural gas pipeline network for external output.

[0066] Specifically, the target separation gas is pressurized and then decarburized and purified, including extracting the target separation gas, constructing medium-pressure regenerated gas, adjusting the pressure of the medium-pressure regenerated gas to the pressure level of 4.0-5.0 MPa of a medium-pressure external pipeline through an adjusting valve, inputting the medium-pressure regenerated gas into a heater through a process control valve, inputting the heated medium-pressure regenerated gas into a decarburization adsorption tower that needs to be heated and regenerated to heat and regenerate the adsorbent, and inputting the heated medium-pressure regenerated gas into a medium-pressure natural gas pipeline network after cooling.

[0067] The method S43 provided by the embodiment of the application further includes:

[0068] S431: when the heating and regeneration of the decarburization adsorption tower is completed, the medium-pressure regenerated gas is input into the decarburization adsorption tower through a process control valve without passing through a heater;

[0069] S432: the medium-pressure regenerated gas is input into the decarburization adsorption tower and cooled and purged by the adsorbent;

[0070] S433: the medium-pressure regenerated gas after cooling and purging is cooled by a cooler and then output into a medium-pressure natural gas pipeline network.

[0071] Specifically, when the heating and regeneration of the decarburization adsorption tower is completed, the medium-pressure regenerated gas is input into the decarburization adsorption tower through a process control valve without passing through a heater, the medium-pressure regenerated gas is cooled and purged by the adsorbent, and finally, the medium-pressure regenerated gas after cooling and purging is cooled by a cooler and then output into a medium-pressure natural gas pipeline network.

[0072] The technical scheme provided by the embodiment of the present application sequentially inputs the natural gas of the underground gas storage into the dehydration adsorption tower, the mercury removal tower and the dust filter arranged in parallel to complete preliminary purification. The natural gas after preliminary purification is input into the high-pressure pre-cooling heat exchanger, the high-pressure main cooling heat exchanger and the high-pressure supercooling heat exchanger to be cooled. The natural gas after cooling is treated by the first-stage jet pump to obtain a gas-liquid mixture, and the gas-liquid mixture is input into the first-stage separator. The separated gas of the first-stage separator is subjected to re-heating operation, and the gas separation of the medium-pressure gas after re-heating is performed to pressurize the target separated gas for decarburization purification. The target separated gas after decarburization purification is sequentially cooled by the medium-pressure pre-cooling heat exchanger and the medium-pressure main cooling heat exchanger. The target separated gas after cooling is treated by the second-stage jet pump to obtain a gas-liquid mixture, and the gas-liquid mixture is input into the second-stage separator. The low-pressure liquid output from the bottom of the second-stage separator is throttled by the regulating valve and then input into the fourth-stage separator. The liquid output from the bottom of the fourth-stage separator is stored as LNG product, and the gas output from the top of the fourth-stage separator is input into the second-stage jet pump for recycling. A circulating cold source supply rule is set, the by-products of the first-stage separator, the medium-pressure pre-cooling heat exchanger, the high-pressure main cooling heat exchanger and the third-stage separator are collected based on the circulating cold source supply rule, and the cold source supply for the preparation process of the LNG product is performed based on the by-products. The recycling of the regenerated gas is realized, the high-pressure natural gas is jetted by the first-stage jet pump to reduce the pressure, the medium-pressure external natural gas and the cold energy required for the cooling of the medium-pressure natural gas are obtained, the temperature regulation energy consumption of the high-pressure natural gas during the external output of the underground gas storage is reduced, and the pressure difference energy waste of the high-pressure natural gas is avoided. The technical problems of high temperature regulation energy consumption and high-pressure natural gas pressure difference energy waste during the external output of the underground gas storage in the prior art are solved.

[0073] Embodiment two

[0074] Based on the same inventive concept as the process method for preparing LNG based on the differential pressure of high-pressure natural gas of an underground gas storage in the foregoing embodiment, the present application also provides a system for the process method for preparing LNG based on the differential pressure of high-pressure natural gas of an underground gas storage. The system can be realized by hardware and / or software, and can be integrated in an electronic device to execute the method provided by any embodiment of the present application. Figure 3 As shown in the figure, the system comprises:

[0075] A preliminary purification module 11 is configured to sequentially input the natural gas of the underground gas storage into the dehydration adsorption tower, the mercury removal tower and the dust filter arranged in parallel to complete preliminary purification.

[0076] A high-pressure cooling module 12 is configured to input the natural gas after preliminary purification into the high-pressure pre-cooling heat exchanger, the high-pressure main cooling heat exchanger and the high-pressure supercooling heat exchanger to be cooled.

[0077] The gas-liquid mixture acquisition module 13 is used to process the cooled natural gas through a primary jet pump to obtain a gas-liquid mixture and input the gas-liquid mixture into a primary separator;

[0078] The decarbonization and purification module 14 is used to perform a reheating operation on the gas separated by the primary separator, and to perform gas separation of the medium-pressure gas after reheating, and to perform decarbonization and purification on the target separated gas after pressurization.

[0079] The medium-pressure cooling module 15 is used to cool the target separated gas after decarbonization and purification by passing it sequentially through a medium-pressure pre-cooling heat exchanger and a medium-pressure main cooling heat exchanger.

[0080] The gas-liquid mixture acquisition module 16 is used to process the cooled target gas through a secondary jet pump to obtain a gas-liquid mixture, and input the gas-liquid mixture into the secondary separator.

[0081] The recycling module 17 is used to throttle the low-pressure liquid output from the bottom of the secondary separator through a regulating valve and then enter the fourth-stage separator. The liquid output from the bottom of the fourth-stage separator is stored as LNG product, and the gas output from the top of the fourth-stage separator enters the secondary injection pump for recycling.

[0082] The cold source supply module 18 is used to set the circulating cold source supply rules, collect the byproducts of the first-stage separator, the medium-pressure precooling heat exchanger, the high-pressure main cooling heat exchanger, and the third-stage separator based on the circulating cold source supply rules, and supply the cold source for the LNG product preparation process based on the byproducts.

[0083] Furthermore, the preliminary purification module 11 is also used for:

[0084] Before being fed into the dehydration adsorption tower, the natural gas is extracted to generate regenerated gas;

[0085] The regenerated gas is cooled and purged through the dehydration adsorption tower and then heated by the regenerated gas heater.

[0086] The heated regeneration gas is reintroduced into the dehydration adsorption tower to heat and regenerate the adsorbent inside the tower.

[0087] After the adsorbent regeneration is completed, the regenerated gas undergoes a predetermined treatment, and the treatment result is mixed with the natural gas and then fed into the dehydration adsorption tower.

[0088] Furthermore, the preliminary purification module 11 is also used for:

[0089] The regenerated gas is fed into a cooler for cooling, and the cooled regenerated gas is pre-cooled by a heat exchanger.

[0090] The pre-cooled regeneration gas is supercooled by a cold gas unit, and then separated from free water by a dehydration separator;

[0091] The regeneration gas output from the dehydration separator is warmed by a heat exchanger, and then mixed with the natural gas and input into the dehydration adsorption tower.

[0092] Further, the gas-liquid mixture obtaining module 16 is further used for:

[0093] Obtaining non-target separated gas in the primary separator;

[0094] The low-pressure gas output from the top of the secondary separator is warmed by a medium-pressure main cold heat exchanger, a high-pressure supercooling heat exchanger, and a high-pressure pre-cooling heat exchanger return flow channel, and the warmed low-pressure gas is pressurized to medium pressure by a BOG compressor;

[0095] The non-target separated gas and the pressurized low-pressure gas are output through the medium-pressure pipeline.

[0096] Further, the cold source supply module 18 is further used for:

[0097] Collecting the output medium-pressure liquid at the bottom of the primary separator, and adjusting the medium-pressure liquid to a low-pressure gas-liquid mixture by an adjusting valve;

[0098] Inputting the low-pressure gas-liquid mixture into the medium-pressure pre-cooling heat exchanger as a cold source of the medium-pressure pre-cooling heat exchanger;

[0099] Collecting the first low-pressure gas-liquid mixture output from the medium-pressure pre-cooling heat exchanger, and inputting the first low-pressure gas-liquid mixture into the return flow channel of the high-pressure main cold heat exchanger as a cold source of the high-pressure main cold heat exchanger;

[0100] Collecting the second low-pressure gas-liquid mixture output from the high-pressure main cold heat exchanger, inputting the second low-pressure gas-liquid mixture into a tertiary separator, and mixing the output low-pressure liquid with the low-pressure gas in the return flow channel of the medium-pressure main cold heat exchanger;

[0101] The mixing result is used as a cold source of the high-pressure supercooling heat exchanger and the high-pressure pre-cooling heat exchanger.

[0102] Further, the decarburization purification module 14 is further used for:

[0103] Extracting the target separated gas, constructing a medium-pressure regeneration gas, and adjusting the pressure of the medium-pressure regeneration gas to the pressure level of 4.0 MPa-5.0 MPa of the medium-pressure output pipeline by an adjusting valve;

[0104] Heating the medium-pressure regeneration gas by a process control valve input heater;

[0105] The heated medium-pressure regeneration gas is input into the desorption tower to heat and regenerate the adsorbent;

[0106] The heated medium-pressure regeneration gas is cooled and then output to the medium-pressure natural gas pipeline network.

[0107] Further, the decarburization purification module 14 is also used for:

[0108] When the heating and regeneration of the decarburization adsorption tower is completed, the medium-pressure regeneration gas is not passed through the heater via the process control valve;

[0109] The medium-pressure regeneration gas is input into the decarburization adsorption tower and cooled and purged by the adsorbent;

[0110] The cooled and purged medium-pressure regeneration gas is cooled by the cooler and then output to the medium-pressure natural gas pipeline network.

[0111] Each unit and module included is only divided according to the functional logic, but is not limited to the above division, as long as the corresponding functions can be realized; in addition, the specific names of each functional unit are only for easy mutual differentiation, and do not limit the protection scope of the present application.

[0112] Example Three

[0113] Figure 4 The structural schematic diagram of the electronic device provided for the third embodiment of the present application shows a block diagram of an exemplary electronic device suitable for implementing the embodiments of the present application. Figure 4 The electronic device shown is only an example and should not bring any limitation to the functions and use range of the embodiments of the present application. As Figure 4 As shown, the electronic device includes a processor 31, a memory 32, an input device 33 and an output device 34; the number of processors 31 in the electronic device can be one or more, Figure 4 Taking one processor 31 as an example, the processor 31, the memory 32, the input device 33 and the output device 34 in the electronic device can be connected through a bus or other means, Figure 4 Taking connection through a bus as an example.

[0114] The memory 32, as a kind of computer readable storage medium, can be used to store software programs, computer executable programs and modules, such as the program instructions / modules corresponding to the process method for preparing LNG by differential pressure of high-pressure natural gas based on underground gas storage of the embodiments of the present application. The processor 31 executes the software programs, instructions and modules stored in the memory 32, thereby performing various functional applications and data processing of the computer device, i.e. implementing the above-mentioned process method for preparing LNG by differential pressure of high-pressure natural gas based on underground gas storage.

[0115] Note that the above merely describes preferred embodiments of the present application and the principles of the technology applied. Those skilled in the art will understand that the present application is not limited to the specific embodiments described herein, and that various obvious changes, modifications and substitutions can be made without departing from the scope of the present application. Therefore, although the present application has been described in detail through the above embodiments, the present application is not limited to the above embodiments, and can include more other equivalent embodiments without departing from the concept of the present application, and the scope of the present application is determined by the scope of the claims.

Claims

1. A process method for pressurizing LNG using high-pressure natural gas differential pressure in an underground gas storage facility, characterized in that, The method includes: The natural gas from the underground gas storage facility is sequentially fed into a dehydration adsorption tower, a mercury removal tower, and a dust filter that are connected in parallel to complete the initial purification. The natural gas, after initial purification, is fed into the high-pressure pre-cooling heat exchanger, high-pressure main cooling heat exchanger, and high-pressure subcooling heat exchanger for cooling. The cooled natural gas is processed by a primary jet pump to obtain a gas-liquid mixture, which is then fed into a primary separator. The gas separated by the first-stage separator is subjected to a reheating operation, and the medium-pressure gas after reheating is separated. The target gas is then pressurized and decarbonized for purification. The target separated gas, after decarbonization and purification, is cooled sequentially by passing it through a medium-pressure pre-cooling heat exchanger and a medium-pressure main cooling heat exchanger. The target gas after cooling is processed by a secondary jet pump to obtain a gas-liquid mixture, which is then fed into a secondary separator. The low-pressure liquid output from the bottom of the secondary separator is throttled through a regulating valve and then enters the fourth-stage separator. The liquid output from the bottom of the fourth-stage separator is stored as LNG product, and the gas output from the top of the fourth-stage separator enters the secondary injection pump for recycling. Set up a circulating cold source supply rule, collect the byproducts of the first-stage separator, the medium-pressure precooling heat exchanger, the high-pressure main cooling heat exchanger, and the third-stage separator based on the circulating cold source supply rule, and supply the cold source for the LNG product preparation process based on the byproducts. Collect the medium-pressure liquid output from the bottom of the first-stage separator, and adjust the medium-pressure liquid into a low-pressure gas-liquid mixture through a regulating valve; The low-pressure gas-liquid mixture is fed into the medium-pressure precooling heat exchanger as a cold source for the medium-pressure precooling heat exchanger. Collect the first low-pressure gas-liquid mixture output from the medium-pressure precooling heat exchanger, and input the first low-pressure gas-liquid mixture into the reflux channel of the high-pressure main cooling heat exchanger as the cold source of the high-pressure main cooling heat exchanger. The second low-pressure gas-liquid mixture output from the high-pressure main refrigeration heat exchanger is collected and fed into a three-stage separator to mix the output low-pressure liquid with the low-pressure gas in the reflux channel of the medium-pressure main refrigeration heat exchanger. The mixture is used as a cold source for the high-pressure subcooling heat exchanger and the high-pressure precooling heat exchanger.

2. The method as described in claim 1, characterized in that, The method further includes: Before being fed into the dehydration adsorption tower, the natural gas is extracted to generate regenerated gas; The regenerated gas is cooled and purged through the dehydration adsorption tower and then heated by the regenerated gas heater. The heated regeneration gas is reintroduced into the dehydration adsorption tower to heat and regenerate the adsorbent inside the tower. After the adsorbent regeneration is completed, the regenerated gas undergoes a predetermined treatment, and the treatment result is mixed with the natural gas and then fed into the dehydration adsorption tower.

3. The method as described in claim 2, characterized in that, The step of subjecting the regenerated gas to a predetermined treatment, mixing the treatment result with the natural gas, and then inputting the mixture into the dehydration adsorption tower further includes: The regenerated gas is fed into a cooler for cooling, and the cooled regenerated gas is pre-cooled by a heat exchanger. The pre-cooled regenerated gas is subcooled by a chiller unit and then free water is separated by a dehydration separator. The regenerated gas output from the dehydration separator is reheated by a heat exchanger and then mixed with the natural gas before being fed into the dehydration adsorption tower.

4. The method as described in claim 1, characterized in that, The method further includes: Obtain the non-target separated gas in the first-stage separator; The low-pressure gas output from the top of the secondary separator is reheated through the return flow channels of the medium-pressure main cooling heat exchanger, the high-pressure subcooling heat exchanger, and the high-pressure precooling heat exchanger. The reheated low-pressure gas is then pressurized to medium pressure by the BOG compressor. The non-target separated gas and the pressurized low-pressure gas are transported out through the medium-pressure pipeline.

5. The method as described in claim 1, characterized in that, The process of pressurizing and decarbonizing the target separated gas further includes: The target separated gas is extracted to construct medium-pressure regeneration gas, and the pressure of the medium-pressure regeneration gas is adjusted to the medium-pressure external transmission pipeline pressure level of 4.0MPa to 5.0MPa through a regulating valve; The medium-pressure regenerated gas is fed into the heater via a process control valve for heating; The heated medium-pressure regeneration gas is input into the adsorption tower that needs to be heated and regenerated to heat and regenerate the adsorbent. The heated medium-pressure regenerated gas is cooled and then transported out through the medium-pressure natural gas pipeline network.

6. The method as described in claim 5, characterized in that, The method further includes: After the decarbonization adsorption tower has completed its heating and regeneration, the medium-pressure regeneration gas passes through the process control valve without going through the heater. The medium-pressure regeneration gas is fed into the decarbonization adsorption tower and cooled and purged by the adsorbent. The medium-pressure regenerated gas, after being cooled and purged, is then cooled by a cooler and exported through the medium-pressure natural gas pipeline network.

7. A process system for pressurizing LNG using high-pressure natural gas differential pressure in an underground gas storage facility, characterized in that, The system includes: The preliminary purification module is used to sequentially input the natural gas from the underground gas storage into the parallel-connected dehydration adsorption tower, mercury removal tower, and dust filter to complete the preliminary purification. The high-pressure cooling module is used to cool the pre-purified natural gas by feeding it into the high-pressure pre-cooling heat exchanger, the high-pressure main cooling heat exchanger, and the high-pressure subcooling heat exchanger. A gas-liquid mixture acquisition module is used to process the cooled natural gas through a primary jet pump to obtain a gas-liquid mixture, and input the gas-liquid mixture into a primary separator; The decarbonization and purification module is used to perform a reheating operation on the gas separated by the primary separator, and to perform gas separation of the medium-pressure gas after reheating, and to decarbonize and purify the target separated gas after pressurization. The medium-pressure cooling module is used to cool the target separated gas after decarbonization and purification by passing it sequentially through a medium-pressure pre-cooling heat exchanger and a medium-pressure main cooling heat exchanger. The gas-liquid mixture acquisition module is used to process the cooled target gas through a secondary jet pump to obtain a gas-liquid mixture, and then input the gas-liquid mixture into the secondary separator. The recycling module is used to throttle the low-pressure liquid output from the bottom of the secondary separator through a regulating valve and then enter the fourth-stage separator. The liquid output from the bottom of the fourth-stage separator is stored as LNG product, and the gas output from the top of the fourth-stage separator enters the secondary injection pump for recycling. The cold source supply module is used to set the circulating cold source supply rules, collect the byproducts of the first-stage separator, the medium-pressure precooling heat exchanger, the high-pressure main cooling heat exchanger, and the third-stage separator based on the circulating cold source supply rules, and supply the cold source for the LNG product preparation process based on the byproducts. The cold source supply module is also used for: Collect the medium-pressure liquid output from the bottom of the first-stage separator, and adjust the medium-pressure liquid into a low-pressure gas-liquid mixture through a regulating valve; The low-pressure gas-liquid mixture is fed into the medium-pressure precooling heat exchanger as a cold source for the medium-pressure precooling heat exchanger. Collect the first low-pressure gas-liquid mixture output from the medium-pressure precooling heat exchanger, and input the first low-pressure gas-liquid mixture into the reflux channel of the high-pressure main cooling heat exchanger as the cold source of the high-pressure main cooling heat exchanger. The second low-pressure gas-liquid mixture output from the high-pressure main refrigeration heat exchanger is collected and fed into a three-stage separator to mix the output low-pressure liquid with the low-pressure gas in the reflux channel of the medium-pressure main refrigeration heat exchanger. The mixture is used as a cold source for the high-pressure subcooling heat exchanger and the high-pressure precooling heat exchanger.

8. An electronic device, characterized in that, The electronic device includes: Memory, used to store executable instructions; The processor, when executing executable instructions stored in the memory, implements the process method for pressurizing LNG based on high-pressure natural gas differential pressure in an underground gas storage facility as described in any one of claims 1 to 6.

9. A computer-readable medium having a computer program stored thereon, characterized in that, When executed by the processor, the program implements a process method for pressurizing LNG based on the differential pressure of high-pressure natural gas in an underground gas storage facility, as described in any one of claims 1-6.

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