Gas storage low-energy-consumption dew point control method and device

Abstract

The invention relates to the technical field of gas production dew point control of a gas storage, in particular to a low-energy-consumption dew point control method and device for the gas storage. In the gas production dew point control method, raw material gas enters a station and then is subjected to gas-liquid separation, wet natural gas is conveyed into a three-flow heat exchanger, ethylene glycol is injected into the wet natural gas, and the anti-freezing wet natural gas is from top to bottom; after the pre-cooled wet natural gas is refrigerated again, the low-temperature wet natural gas is conveyed into the low-temperature separator for gas-liquid separation, the low-temperature dry gas is conveyed to the bottom of the three-flow heat exchanger for reverse heat exchange with the anti-freezing wet natural gas, and the low-temperature dry gas is output through reheated high-pressure output dry gas. The system comprises a three-flow heat exchanger, a gas-liquid separator, an air cooler, a propane external cooling evaporator and a low-temperature separator. According to the method, the injection-production cycle characteristics of the gas storage and the climate change condition of the area where the gas storage is located are combined, low-temperature dehydration and dealkylation of air enthalpy difference refrigeration and propane auxiliary refrigeration are adopted, and the purposes of saving energy, reducing carbon and reducing cost are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of gas storage dew point control for gas extraction, and relates to a low-energy consumption dew point control method and device for a gas storage. Background Art

[0002] In summer, the ambient temperature is high, the market natural gas consumption is low, and the surplus natural gas needs to be stored. In winter, the weather is cold and the natural gas consumption increases exponentially. Therefore, the gas storage in the north has the characteristics of summer injection and winter production, and large injection and production volume. Usually, the gas injection period starts from mid-March to mid-October each year, and the gas production period starts from late November each year to early March of the following year. For gas storages that do not have surplus pressure energy available during the gas production period, the dew point control processes that can be used mainly include propane external cooling low-temperature separation dehydration and dehydrocarbon process, throttling and pressure reduction low-temperature separation dehydration and dehydrocarbon + pressurized external transmission process, and silica gel adsorption dehydration and dehydrocarbon process. Among them, the silica gel adsorption dehydration and dehydrocarbon process has not been actually applied in China at present.

[0003] The existing dehydration and dehydrocarbon removal process fails to fully utilize the ambient cold in gas storage applications, resulting in high energy consumption. In addition, the hydrocarbon water dew point of natural gas treated by the existing air-cooled low-temperature dehydration technology in the natural gas gathering and transportation system changes with the ambient temperature. When the ambient temperature is high, the hydrocarbon water dew point of the treated natural gas does not meet the standard, and the hydrocarbon water dew point index is unstable. Condensed liquid will precipitate in the gathering and transportation pipeline, and the pipeline needs to be equipped with a ball cleaning system.

[0004] Therefore, it is necessary to develop a new low-energy dew point control method and device for gas storage, so as to meet the refrigeration demand when the ambient temperature at the end of gas production and the temperature of the incoming raw gas increase, and ensure that the hydrocarbon water dew point of the exported gas meets the standard during the entire gas production period. Summary of the invention

[0005] The present invention provides a low-energy consumption dew point control method and device for a gas storage facility, which overcomes the above-mentioned deficiencies of the prior art and can effectively solve the problems that after being treated by air-cooling and low-temperature dehydration technology in the existing natural gas gathering and transportation system, the hydrocarbon water dew point of the treated natural gas does not meet the standard when the ambient temperature is high, condensed liquid will precipitate in the gathering and transportation pipeline, the pipeline needs to be equipped with a ball cleaning device, and the ambient cold capacity cannot be fully utilized, resulting in high energy consumption.

[0006] One of the technical solutions of the present invention is achieved through the following measures: a low-energy consumption dew point control method for a gas storage reservoir is carried out according to the following steps: the first step is to separate the raw gas into gas and liquid according to the temperature value of the raw gas when it enters the station, and obtain the first mixed liquid phase and wet natural gas respectively; the second step is to transport the first mixed liquid phase to the downstream process for recycling and treatment, and the wet natural gas is transported to a three-stream heat exchanger; the third step is to inject ethylene glycol into the wet natural gas after the wet natural gas enters the three-stream heat exchanger to obtain antifreeze wet natural gas; the fourth step is to inject ethylene glycol into the antifreeze wet natural gas. From top to bottom, reverse heat exchange is performed with the low-temperature dry gas from bottom to top after low-temperature separation to pre-cool the temperature and obtain pre-cooled wet natural gas; in the fifth step, the pre-cooled wet natural gas is refrigerated again to obtain low-temperature wet natural gas; in the sixth step, the low-temperature wet natural gas is transported to the low-temperature separator for gas-liquid separation to obtain low-temperature dry gas and the second mixed liquid phase respectively; in the seventh step, the low-temperature dry gas is transported to the bottom of the three-stream heat exchanger for reverse heat exchange with the antifreeze wet natural gas. After the low-temperature dry gas is reheated, high-pressure external dry gas is obtained for external transmission, and the second mixed liquid phase is sent to the downstream process for hydrocarbon alcohol separation and recovery.

[0007] The following is a further optimization and / or improvement of one of the above-mentioned technical solutions: In the first step above, when the temperature of the raw gas entering the station is 25°C to 35°C, the raw gas is directly transported to the gas-liquid separator for gas-liquid separation.

[0008] In the fifth step, when the precooled wet natural gas is cooled again, the precooled wet natural gas is cooled to a temperature of -10°C to -5°C by the air enthalpy difference of the air cooler to obtain low-temperature wet natural gas.

[0009] In the first step above, when the temperature of the raw gas entering the station is higher than 35°C, the raw gas is first transported to the air cooler after entering the station. When the temperature is cooled to 25°C to 35°C by air cooling, the raw gas is then transported to the gas-liquid separator for gas-liquid separation.

[0010] In the fifth step, when the precooled wet natural gas is refrigerated again, the precooled wet natural gas is cooled to a temperature of -10°C to -5°C by a propane external cooling evaporator to obtain low-temperature wet natural gas.

[0011] In the first step, the first mixed liquid phase is a mixed liquid of free condensate oil and water. In the sixth step, the second mixed liquid phase is a mixed liquid of ethylene glycol water and light hydrocarbons.

[0012] The second technical solution of the present invention is achieved through the following measures: a device for implementing the low-energy dew point control method and device for a gas storage reservoir, comprising a three-stream heat exchanger, a gas-liquid separator, an air cooler, a propane external cooling evaporator and a low-temperature separator, the top inlet of the gas-liquid separator is fixedly connected with a raw gas inlet pipeline, the bottom outlet of the gas-liquid separator is fixedly connected with a first mixed liquid phase discharge pipeline, the top outlet of the gas-liquid separator and the top inlet of the three-stream heat exchanger are fixedly connected with a wet natural gas inlet pipeline, the first outlet of the lower part of the three-stream heat exchanger and the inlet of the air cooler are fixedly connected with a pre-cooled wet natural gas outlet pipeline, the outlet of the air cooler is connected to the propane external cooling evaporator, and the outlet of the air cooler is connected to the propane external cooling evaporator. A low-temperature wet natural gas inlet pipeline is fixedly connected between the inlets, a low-temperature wet natural gas outlet pipeline is fixedly connected between the outlet of the propane external cooling evaporator and the top inlet of the low-temperature separator, a low-temperature dry gas inlet pipeline is fixedly connected between the top outlet of the low-temperature separator and the lower inlet of the three-stream heat exchanger, a high-pressure external dry gas pipeline is fixedly connected to the upper outlet of the three-stream heat exchanger, a second mixed liquid phase inlet pipeline is fixedly connected between the bottom outlet of the low-temperature separator and the first upper inlet of the three-stream heat exchanger, a second mixed liquid phase discharge pipeline is fixedly connected to the second lower outlet of the three-stream heat exchanger, and an ethylene glycol injection pipeline is fixedly connected to the second upper inlet of the three-stream heat exchanger.

[0013] The following is a further optimization and / or improvement of the second technical solution of the above invention: A first valve is fixedly installed on the raw gas inlet pipeline, a second valve is fixedly installed on the pre-cooled wet natural gas outlet pipeline, and a third valve is fixedly installed on the low-temperature wet natural gas inlet pipeline.

[0014] A first bypass pipeline is fixedly connected between the precooling wet natural gas outlet pipeline between the three-stream heat exchanger and the second valve and the low-temperature wet natural gas inlet pipeline between the third valve and the propane external cooling evaporator, and a fourth valve is fixedly installed on the first bypass pipeline.

[0015] A second bypass pipeline is fixedly connected between the raw gas inlet pipeline between the inlet of the raw gas inlet pipeline and the first valve and the pre-cooling wet natural gas outlet pipeline between the second valve and the air cooler, a third bypass pipeline is fixedly connected between the low-temperature wet natural gas inlet pipeline between the air cooler and the third valve and the raw gas inlet pipeline between the first valve and the gas-liquid separator, a fifth valve is fixedly connected to the second bypass pipeline, and a sixth valve is fixedly installed on the third bypass pipeline.

[0016] The present invention combines the injection and production cycle characteristics of the gas storage reservoir and the climate change conditions in the area where the gas storage reservoir is located, and adopts low-temperature dehydration and dehydrocarbon removal using air enthalpy difference refrigeration and propane-assisted refrigeration, thereby achieving the goals of energy saving, carbon reduction and cost reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Attached Figure 1This is a schematic diagram of the process flow of Example 7 of the present invention.

[0018] The codes in the attached drawings are: 1 is a three-stream heat exchanger, 2 is a gas-liquid separator, 3 is an air cooler, 4 is a propane external cooling evaporator, 5 is a low-temperature separator, 6 is a raw gas inlet pipeline, 7 is a first mixed liquid phase discharge pipeline, 8 is a wet natural gas inlet pipeline, 9 is a pre-cooling wet natural gas outlet pipeline, 10 is a low-temperature wet natural gas inlet pipeline, 11 is a low-temperature wet natural gas outlet pipeline, 12 is a low-temperature dry gas inlet pipeline, 13 is a high-pressure external transmission dry gas pipeline, 14 is a second mixed liquid phase inlet pipeline, 15 is a second mixed liquid phase discharge pipeline, 16 is an ethylene glycol injection pipeline, 17 is a first valve, 18 is a second valve, 19 is a third valve, 20 is a first bypass pipeline, 21 is a fourth valve, 22 is a second bypass pipeline, 23 is a third bypass pipeline, 24 is a fifth valve, and 25 is a sixth valve. DETAILED DESCRIPTION

[0019] The present invention is not limited by the following embodiments, and specific implementation methods can be determined based on the technical solution of the present invention and actual conditions.

[0020] The present invention will be further described below in conjunction with embodiments: Embodiment 1: As attached Figure 1 As shown, the low-energy consumption dew point control method of the gas storage is carried out according to the following steps: the first step is that after the raw gas enters the station, the raw gas is separated into gas and liquid according to the temperature value of the raw gas when entering the station, and the first mixed liquid phase and wet natural gas are obtained respectively; the second step is to transport the first mixed liquid phase to the downstream process for recycling and treatment, and the wet natural gas is transported to the three-stream heat exchanger 1; the third step is that after the wet natural gas enters the three-stream heat exchanger 1, ethylene glycol is injected into the wet natural gas to obtain antifreeze wet natural gas; the fourth step is that the antifreeze wet natural gas is separated from the low temperature from top to bottom. Then, the low-temperature dry gas is reversely heat exchanged from bottom to top for pre-cooling to obtain pre-cooled wet natural gas; in the fifth step, the pre-cooled wet natural gas is refrigerated again to obtain low-temperature wet natural gas; in the sixth step, the low-temperature wet natural gas is transported to the low-temperature separator 5 for gas-liquid separation to obtain low-temperature dry gas and the second mixed liquid phase respectively; in the seventh step, the low-temperature dry gas is transported to the bottom of the three-stream heat exchanger 1 for reverse heat exchange with the antifreeze wet natural gas. After the low-temperature dry gas is reheated, high-pressure external dry gas is obtained for external transmission, and the second mixed liquid phase is sent to the downstream process for hydrocarbon alcohol separation and recovery.

[0021] Embodiment 2: As attached Figure 1 As shown, as an optimization of the above embodiment, as shown in the attached Figure 1 As shown, in the first step, when the temperature of the raw gas entering the station is 25°C to 35°C, the raw gas is directly transported to the gas-liquid separator 2 for gas-liquid separation.

[0022] Embodiment 3: As attached Figure 1As shown, as an optimization of the above embodiment 2, as shown in the attached Figure 1 As shown, in the fifth step, when the precooled wet natural gas is refrigerated again, the precooled wet natural gas is cooled to a temperature of -10°C to -5°C by the air enthalpy difference of the air cooler 3 to obtain low-temperature wet natural gas.

[0023] Embodiment 4: As attached Figure 1 As shown, as an optimization of the above embodiment, as shown in the attached Figure 1 As shown, in the first step, when the temperature of the raw gas entering the station is higher than 35°C, the raw gas is first transported to the air cooler 3 after entering the station. When the temperature is cooled to 25°C to 35°C by air cooling, the raw gas is then transported to the gas-liquid separator 2 for gas-liquid separation.

[0024] Embodiment 5: As attached Figure 1 As shown, as an optimization of the above-mentioned embodiment 4, as shown in the attached Figure 1 As shown, in the fifth step, when the precooled wet natural gas is refrigerated again, the precooled wet natural gas is cooled to a temperature of -10°C to -5°C by the propane external cooling evaporator 4 to obtain low-temperature wet natural gas.

[0025] According to needs, in the present invention, when the temperature of the natural gas after air cooling meets the designed low-temperature separation temperature, the propane external cooling evaporator 4 can stop refrigeration and be in a standby state. When the temperature after air cooling is higher than the low-temperature separation temperature, the propane external cooling evaporator 4 operates and adjusts the refrigeration load according to the temperature of the natural gas after air cooling, so that the natural gas refrigeration temperature meets the low-temperature separation temperature requirement.

[0026] Example 6: As an optimization of the above example, in the first step, the first mixed liquid phase is a mixture of free condensate oil and water, and in the sixth step, the second mixed liquid phase is a mixture of ethylene glycol water and light hydrocarbons.

[0027] The present invention utilizes the regional environmental characteristics and the characteristics of the gas storage gas production cycle to develop a low-energy dew point control process for the gas storage using air enthalpy difference refrigeration + propane auxiliary refrigeration. Through air cooling, the cold air of the northern winter atmosphere is fully utilized to achieve gas storage gas production refrigeration and cooling. When used in combination with propane refrigeration, it can meet the refrigeration needs when the ambient temperature at the end of gas production and the temperature of the incoming raw gas rise, ensuring that the hydrocarbon water dew point of the exported gas meets the standards during the entire gas production period.

[0028] In the present invention, in order to prevent freezing of wet natural gas during the heat exchange and temperature reduction process, ethylene glycol can be injected into the wet natural gas at the top of the three-stream heat exchanger 1 to prevent freezing.

[0029] Embodiment 7: As attached Figure 1As shown, the device for implementing the low-energy consumption dew point control method of the gas storage reservoir comprises a three-stream heat exchanger 1, a gas-liquid separator 2, an air cooler 3, a propane external cooling evaporator 4 and a low-temperature separator 5. The top inlet of the gas-liquid separator 2 is fixedly connected with a raw gas inlet pipeline 6, the bottom outlet of the gas-liquid separator 2 is fixedly connected with a first mixed liquid phase discharge pipeline 7, the top outlet of the gas-liquid separator 2 and the top inlet of the three-stream heat exchanger 1 are fixedly connected with a wet natural gas inlet pipeline 8, the first outlet of the lower part of the three-stream heat exchanger 1 and the inlet of the air cooler 3 are fixedly connected with a pre-cooled wet natural gas outlet pipeline 9, and the outlet of the air cooler 3 and the inlet of the propane external cooling evaporator 4 are fixedly connected with a low-temperature wet natural gas outlet pipeline 8. A low-temperature wet natural gas outlet pipeline 11 is fixedly connected between the outlet of the propane external cooling evaporator 4 and the top inlet of the low-temperature separator 5, a low-temperature dry gas inlet pipeline 12 is fixedly connected between the top outlet of the low-temperature separator 5 and the lower inlet of the three-stream heat exchanger 1, a high-pressure external dry gas pipeline 13 is fixedly connected to the upper outlet of the three-stream heat exchanger 1, a second mixed liquid phase inlet pipeline 14 is fixedly connected between the bottom outlet of the low-temperature separator 5 and the first upper inlet of the three-stream heat exchanger 1, a second mixed liquid phase discharge pipeline 15 is fixedly connected to the second lower outlet of the three-stream heat exchanger 1, and an ethylene glycol injection pipeline 16 is fixedly connected to the second upper inlet of the three-stream heat exchanger 1.

[0030] According to needs, when the temperature of the natural gas after air cooling meets the designed low-temperature separation temperature, the propane external cooling evaporator 4 can stop refrigeration and be in standby state. At this time, the propane external cooling evaporator 4 can be used only as a pipeline for medium inlet and outlet.

[0031] Embodiment 8: As attached Figure 1 As shown, as an optimization of the above embodiment, a first valve 17 is fixedly installed on the raw gas inlet pipeline 6, a second valve 18 is fixedly installed on the pre-cooling wet natural gas outlet pipeline 9, and a third valve 19 is fixedly installed on the low-temperature wet natural gas inlet pipeline 10.

[0032] Embodiment 9: As attached Figure 1 As shown, as an optimization of the above embodiment, a first bypass pipeline 20 is fixedly connected between the pre-cooling wet natural gas outlet pipeline 9 between the three-stream heat exchanger 1 and the second valve 18 and the low-temperature wet natural gas inlet pipeline 10 between the third valve 19 and the propane external cooling evaporator 4, and a fourth valve 21 is fixedly installed on the first bypass pipeline 20.

[0033] Embodiment 10: As attached Figure 1As shown, as an optimization of the above embodiment, a second bypass pipeline 22 is fixedly connected between the raw gas inlet pipeline 6 between the inlet of the raw gas inlet pipeline 6 and the first valve 17 and the pre-cooling wet natural gas outlet pipeline 9 between the second valve 18 and the air cooler 3, a third bypass pipeline 23 is fixedly connected between the low-temperature wet natural gas inlet pipeline 10 between the air cooler 3 and the third valve 19 and the raw gas inlet pipeline 6 between the first valve 17 and the gas-liquid separator 2, a fifth valve 24 is fixedly connected to the second bypass pipeline 22, and a sixth valve 25 is fixedly installed on the third bypass pipeline 23.

[0034] According to needs, in the later period of gas production in the gas storage (late February to early March), the ambient temperature and the temperature of the incoming raw gas both rise, and the raw gas can first go to the air cooler 3 through the second bypass pipeline 22 to air-cool the raw gas, then return through the third bypass pipeline 23, and then go to the three-stream heat exchanger 1 for pre-cooling, and then go directly to the propane external cooling evaporator 4 through the first bypass pipeline 20 of the air cooler 3 to be refrigerated to the designed low-temperature separation temperature. After low-temperature separation, the dry gas is reheated through the three-stream heat exchanger 1 and then transmitted to the outside.

[0035] In the present invention, unless otherwise specified, the equipment and devices used are all publicly known equipment and devices in the art, such as a three-stream heat exchanger 1, a gas-liquid separator 2, an air cooler 3, a propane external cooling evaporator 4 and a low-temperature separator 5.

[0036] As required, the pipelines and equipment of the device for implementing the low-energy dew point control method for gas storage facilities may also be equipped with conventional valves, thermometers, pressure gauges, etc. that are well known and used in the art according to production needs.

[0037] Example 11: The gas production period of a gas storage in a certain northern region starts from November 20th of each year and ends on March 10th of the following year. In the past 10 years, the ambient temperature in this region ranges from -17°C to 2°C from November 20th to December 10th of each year; from -27°C to -9°C from December 10th to February 20th of the following year; and from -19°C to 3°C from February 20th to March 10th.

[0038] November 20 to February 20: Gas production: 1440×10 4 m 3 / d, gas inlet pressure 10.5MPa, temperature 25℃ to 35℃, fourth valve 21, fifth valve 24 and sixth valve 25 are closed, first valve 17, second valve 18 and third valve 19 are opened, after the raw gas enters the station, the free liquid carried by the underground produced gas is separated by the gas-liquid separator 2, and then it goes to the three-stream heat exchanger 1 for precooling to -5℃ to 0℃, and then enters the air cooler 3, and is cooled to -10℃ to -5℃ by the air enthalpy difference, and then enters the low-temperature separator 5 to separate the condensed liquid, and the low-temperature dry gas goes to the three-stream heat exchanger 1 for reheating to 20℃ to 30℃ for external transmission. The hydrocarbon water dew point of the externally transmitted gas is ≤0℃, which meets the requirements of the current specification "Natural Gas" GB 17820-2018 for the handover of natural gas, that is, under the pressure and temperature conditions of the handover point (the ground temperature t≥0℃ at the handover point), there should be no liquid water and liquid hydrocarbons in the natural gas. During the time period when the daytime temperature is higher than -10℃ (about 2 to 3 hours), the propane refrigeration system operates at a small load, and the air-cooled natural gas is further cooled to -10℃ to -5℃ for low-temperature separation. During other periods, the propane external cooling system is on standby and air-cooled by air cooler 3.

[0039] From February 20 to March 10 of the following year, the gas production was 1440×10 4 m 3 / d, the gas inlet pressure is 10.5MPa, the temperature is 35℃ to 45℃, the first valve 17, the second valve 18 and the third valve 19 are closed, the fourth valve 21, the fifth valve 24 and the sixth valve 25 are opened. After the raw gas enters the station, it first goes to the air cooler 3 through the second bypass pipeline to be air-cooled to 25℃, and then enters the gas-liquid separator 2 through the third bypass pipeline 23 to separate the free liquid carried in the produced gas, and goes to the three-stream heat exchanger 1 for pre-cooling to -5℃, and enters the propane external cooling evaporator 4 through the first bypass pipeline 20, and is refrigerated to -10℃ by propane. After entering the low-temperature separator 5 to separate the condensed liquid, the low-temperature dry gas goes to the three-stream heat exchanger 1 for reheating to 30℃ to 40℃ for external transmission. The hydrocarbon water dew point of the exported gas is ≤0℃, which meets the requirements of the current specification "Natural Gas" GB 17820-2018 for the handover of natural gas, that is, under the pressure and temperature conditions of the handover point (the ground temperature at the handover point t≥0℃), there should be no liquid water and liquid hydrocarbons in the natural gas. At the end of gas production, due to the high temperature of the incoming raw gas and the high saturated water content of the natural gas, the second bypass pipeline 22 and the third bypass pipeline 23 can be cooled by air before gas-liquid separation, pre-cooling by the three-stream heat exchanger 1, propane refrigeration, low-temperature separation, and reheating for external transmission.

[0040] In Example 11 of the present invention, the energy consumption of treating 10,000 cubic meters of produced gas in a gas storage in a certain place in the north is about 1.76 kgce, which is about 46.8% lower than the energy consumption of the conventional propane refrigeration dew point control process, and the carbon emission is reduced by about 8.4 kg CO2 / 10 4 m 3Compared with the throttling and depressurization low-temperature separation dehydration and dehydrocarbon removal + pressurized external transmission process, the energy consumption is reduced by about 68.3%, and the carbon emission is reduced by about 20.6 kg CO2 / 10 4 m 3 Therefore, the present invention has the advantages of low production and operation cost, low energy consumption and low carbon emissions.

[0041] In summary, the present invention combines the characteristics of the injection and production cycle of the gas storage reservoir, analyzes the climate change in the area where the gas storage reservoir is located through big data statistics, and through technical and economic analysis, fully utilizes the coldness of the northern winter environment and adopts a low-temperature dehydration and dehydrocarbonization process of air enthalpy difference refrigeration + propane auxiliary refrigeration to achieve the goals of energy saving, carbon reduction and cost reduction.

[0042] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Non-essential technical features can be added or reduced according to actual needs to meet the requirements of different situations.

Claims

1. A low energy consumption dew point control method for a gas storage, characterized in that The process is carried out according to the following steps: First, after the raw gas enters the station, the raw gas is separated into gas and liquid according to the temperature value of the raw gas when entering the station, and the first mixed liquid phase and wet natural gas are obtained respectively; In the second step, the first mixed liquid phase is transported to the downstream process for recovery and treatment, and the wet natural gas is transported to the three-stream heat exchanger; In the third step, after the wet natural gas enters the three-stream heat exchanger, ethylene glycol is injected into the wet natural gas to obtain antifreeze wet natural gas; In the fourth step, the antifreeze wet natural gas is precooled by reverse heat exchange with the low-temperature dry gas from bottom to top after low-temperature separation to obtain precooled wet natural gas; Step 5: The pre-cooled wet natural gas is refrigerated again to obtain low-temperature wet natural gas; In the sixth step, the low-temperature wet natural gas is transported to a low-temperature separator for gas-liquid separation to obtain low-temperature dry gas and a second mixed liquid phase respectively; in the seventh step, the low-temperature dry gas is transported to the bottom of the three-stream heat exchanger for reverse heat exchange with the antifreeze wet natural gas. After the low-temperature dry gas is reheated, high-pressure external dry gas is obtained for external transmission, and the second mixed liquid phase is sent to the downstream process for hydrocarbon alcohol separation and recovery.

2. The low energy consumption dew point control method for gas storage according to claim 1 is characterized in that In the first step, when the temperature of the raw gas entering the station is 25°C to 35°C, the raw gas is directly transported to the gas-liquid separator for gas-liquid separation.

3. The low energy consumption dew point control method for gas storage according to claim 2 is characterized in that In the fifth step, when the precooled wet natural gas is refrigerated again, the precooled wet natural gas is cooled to a temperature of -10°C to -5°C by the air enthalpy difference of the air cooler to obtain low-temperature wet natural gas.

4. The low energy consumption dew point control method for gas storage according to claim 1 is characterized in that In the first step, when the temperature of the raw gas entering the station is higher than 35°C, the raw gas is first transported to the air cooler after entering the station. After being air-cooled to a temperature of 25°C to 35°C, the raw gas is then transported to the gas-liquid separator for gas-liquid separation.

5. The low energy consumption dew point control method for gas storage according to claim 4 is characterized in that In the fifth step, when the pre-cooled wet natural gas is refrigerated again, the pre-cooled wet natural gas is cooled to a temperature of -10°C to -5°C by a propane external cooling evaporator to obtain low-temperature wet natural gas.

6. The low energy consumption dew point control method for a gas storage according to any one of claims 1 to 5, characterized in that In the first step, the first mixed liquid phase is a mixed liquid of free condensate oil and water, and in the sixth step, the second mixed liquid phase is a mixed liquid of ethylene glycol water and light hydrocarbons.

7. A device for implementing the low-energy dew point control method for a gas storage according to any one of claims 1 to 6, characterized in that It includes a three-stream heat exchanger, a gas-liquid separator, an air cooler, a propane external cooling evaporator and a low-temperature separator. The top inlet of the gas-liquid separator is fixedly connected with a raw gas inlet pipeline, the bottom outlet of the gas-liquid separator is fixedly connected with a first mixed liquid phase discharge pipeline, the top outlet of the gas-liquid separator and the top inlet of the three-stream heat exchanger are fixedly connected with a wet natural gas inlet pipeline, the first outlet of the lower part of the three-stream heat exchanger and the inlet of the air cooler are fixedly connected with a pre-cooled wet natural gas outlet pipeline, the outlet of the air cooler and the inlet of the propane external cooling evaporator are fixedly connected with a low-temperature wet natural gas inlet pipeline, and the propane A low-temperature wet natural gas outlet pipeline is fixedly connected between the outlet of the external cooling evaporator and the top inlet of the low-temperature separator, a low-temperature dry gas inlet pipeline is fixedly connected between the top outlet of the low-temperature separator and the lower inlet of the three-stream heat exchanger, a high-pressure external dry gas pipeline is fixedly connected to the upper outlet of the three-stream heat exchanger, a second mixed liquid phase inlet pipeline is fixedly connected between the bottom outlet of the low-temperature separator and the first upper inlet of the three-stream heat exchanger, a second mixed liquid phase discharge pipeline is fixedly connected to the second lower outlet of the three-stream heat exchanger, and an ethylene glycol injection pipeline is fixedly connected to the second upper inlet of the three-stream heat exchanger.

8. The device according to claim 7, characterized in that A first valve is fixedly installed on the raw gas inlet pipeline, a second valve is fixedly installed on the pre-cooled wet natural gas outlet pipeline, and a third valve is fixedly installed on the low-temperature wet natural gas inlet pipeline.

9. The device according to claim 7 or 8, characterized in that A first bypass pipeline is fixedly connected between the precooling wet natural gas outlet pipeline between the three-stream heat exchanger and the second valve and the low-temperature wet natural gas inlet pipeline between the third valve and the propane external cooling evaporator, and a fourth valve is fixedly installed on the first bypass pipeline.

10. The device according to claim 7, 8 or 9, characterized in that A second bypass pipeline is fixedly connected between the raw gas inlet pipeline between the raw gas inlet pipeline inlet and the first valve and the pre-cooling wet natural gas outlet pipeline between the second valve and the air cooler, a third bypass pipeline is fixedly connected between the low-temperature wet natural gas inlet pipeline between the air cooler and the third valve and the raw gas inlet pipeline between the first valve and the gas-liquid separator, a fifth valve is fixedly connected to the second bypass pipeline, and a sixth valve is fixedly installed on the third bypass pipeline.

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