Low-energy dew point control method and device for gas storage

Abstract

The present invention relates to the technical field of gas storage dew point control, and is a low-energy consumption dew point control method and device for gas storage. In the former, gas-liquid separation is performed after the raw gas enters the station, and the wet natural gas is transported to a three-stream heat exchanger. Ethylene glycol is injected into the wet natural gas, and the antifreeze wet natural gas is pre-cooled from top to bottom by reverse heat exchange with low-temperature dry gas. After the pre-cooled wet natural gas is refrigerated again, the low-temperature wet natural gas is transported to a low-temperature separator for gas-liquid separation, and 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. The high-pressure external transmission dry gas after the low-temperature dry gas is reheated is transmitted externally. The latter includes a three-stream heat exchanger, a gas-liquid separator, an air cooler, a propane external cooling evaporator and a low-temperature separator. The present invention combines the characteristics of the injection and production cycle of the gas storage and the climate change conditions in the area where the gas storage is located, and adopts low-temperature dehydration and dehydrogenation by air enthalpy difference refrigeration and propane auxiliary refrigeration to achieve the goals of energy saving, carbon reduction and cost reduction.

Description

Technical Field

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

[0002] In the summer, ambient temperatures are high, and market natural gas consumption is low, requiring surplus natural gas to be stored. Winter, with its cold weather, increases natural gas consumption exponentially. Consequently, northern gas storage facilities feature summer injection and winter production, with large injection and production volumes. The injection period typically runs from mid-March to mid-October, and the production period runs from late November to early March of the following year. For gas storage facilities without excess pressure energy available during the production period, the three main dew point control technologies available include propane external cooling, cryogenic separation and dehydration, throttling and pressure reduction, cryogenic separation and dehydration combined with pressurized external transmission, and silica gel adsorption. However, silica gel adsorption is currently not in practical use in China.

[0003] Existing dehydration and dehydrogenation processes in gas storage applications fail to fully utilize ambient cooling capacity, resulting in high energy consumption. Furthermore, the hydrocarbon-water dew point of natural gas treated with air-cooled, low-temperature dehydration technology in existing natural gas gathering and transportation systems varies with ambient temperature. At high ambient temperatures, the treated natural gas's hydrocarbon-water dew point falls below standard, and the dew point is unstable, leading to condensation in the gathering and transportation pipelines, necessitating ball cleaning.

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

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

[0006] One of the technical solutions of the present invention is achieved through the following measures: a low-energy 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 a 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 From top to bottom, reverse heat exchange is performed with the low-temperature dry gas from bottom to top after low-temperature separation to cool down and pre-cool, thereby obtaining 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:

[0008] 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.

[0009] In the fifth step, when the pre-cooled wet natural gas is cooled again, the pre-cooled wet natural gas is cooled to a temperature of -10°C to -5°C by the air enthalpy difference of the air cooler, thereby obtaining low-temperature wet natural gas.

[0010] In the first step above, when the temperature of the raw gas is higher than 35°C when it enters the station, 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.

[0011] 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 the propane external cooling evaporator to obtain low-temperature wet natural gas.

[0012] In the first step, the first mixed liquid phase is a mixture of free condensate oil and water. In the sixth step, the second mixed liquid phase is a mixture of ethylene glycol water and light hydrocarbons.

[0013] The second technical solution of the present invention is achieved through the following measures: a device for implementing a 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, wherein the top inlet of the gas-liquid separator is fixedly connected to a raw gas inlet pipeline, the bottom outlet of the gas-liquid separator is fixedly connected to 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 to 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 to a pre-cooled wet natural gas outlet pipeline, the outlet of the air cooler is fixedly 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, the second lower outlet of the three-stream heat exchanger is fixedly connected to the second mixed liquid phase discharge pipeline, and the second upper inlet of the three-stream heat exchanger is fixedly connected to the ethylene glycol injection pipeline.

[0014] The following is a further optimization and / or improvement of the second technical solution of the above invention:

[0015] 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.

[0016] A first bypass pipeline is fixedly connected between the pre-cooled 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.

[0017] 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-cooled 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. The second bypass pipeline is fixedly connected with a fifth valve, and the third bypass pipeline is fixedly installed with a sixth valve.

[0018] 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 dehydrogenation using air enthalpy difference refrigeration and propane-assisted refrigeration, thereby achieving the goals of energy conservation, carbon reduction and cost reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Attachment Figure 1This is a schematic diagram of the process flow of Example 7 of the present invention.

[0020] The codes in the accompanying 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 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

[0021] The present invention is not limited to the following embodiments, and specific implementation methods can be determined based on the technical solutions of the present invention and actual conditions.

[0022] The present invention will be further described below in conjunction with the embodiments:

[0023] Example 1: As shown in the attached Figure 1 As shown, the low-energy dew point control method of the gas storage 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 it enters the station, and a first mixed liquid phase and wet natural gas are obtained respectively; second, the first mixed liquid phase is transported to the downstream process for recycling and treatment, and the wet natural gas is transported to the three-stream heat exchanger 1; third, 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; fourth, the antifreeze wet natural gas is separated from the low-temperature gas 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 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 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.

[0024] Example 2: As shown in the attached Figure 1 As shown in the attached figure, as an optimization of the above embodiment, 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.

[0025] Example 3: As shown in the attached Figure 1 As shown in the attached figure, as an optimization of the above embodiment 2, Figure 1 As shown, 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 the air enthalpy difference of the air cooler 3 to obtain low-temperature wet natural gas.

[0026] Example 4: As shown in the attached Figure 1 As shown in the attached figure, as an optimization of the above embodiment, Figure 1 As shown, in the first step, when the temperature of the raw gas is higher than 35°C when it enters the station, 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.

[0027] Example 5: As shown in the attached Figure 1 As shown in the attached example, as an optimization of the above embodiment 4, Figure 1 As shown, 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 the propane external cooling evaporator 4 to obtain low-temperature wet natural gas.

[0028] 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 natural gas temperature after air cooling so that the natural gas refrigeration temperature meets the low-temperature separation temperature requirement.

[0029] 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.

[0030] The present invention utilizes the regional environmental characteristics and the gas production cycle characteristics of the gas storage reservoir to develop a low-energy dew point control process for the gas storage reservoir 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 reservoir 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 standard throughout the entire gas production period.

[0031] In the present invention, in order to prevent the wet natural gas from freezing during the heat exchange and cooling process, ethylene glycol can be injected into the wet natural gas at the top of the three-stream heat exchanger 1 to prevent freezing.

[0032] Example 7: As shown in the attached Figure 1As shown, the device for implementing the low-energy dew point control method for a 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 to a raw gas inlet pipeline 6, the bottom outlet of the gas-liquid separator 2 is fixedly connected to 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 to 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 to a pre-cooled wet natural gas outlet pipeline 9, the outlet of the air cooler 3 and the inlet of the propane external cooling evaporator 4 are fixedly connected to a low-temperature wet natural gas outlet. 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.

[0033] As needed, 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.

[0034] Example 8: As shown in the 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-cooled wet natural gas outlet pipeline 9, and a third valve 19 is fixedly installed on the low-temperature wet natural gas inlet pipeline 10.

[0035] Example 9: As shown in the attached Figure 1 As shown, as an optimization of the above embodiment, a first bypass line 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 line 20.

[0036] Example 10: As shown in the attached Figure 1As shown, as an optimization of the above embodiment, a second bypass line 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 line 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 line 22, and a sixth valve 25 is fixedly installed on the third bypass line 23.

[0037] As needed, 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. The raw gas can first be sent to the air cooler 3 through the second bypass line 22 for air cooling and then returned through the third bypass line 23. It is then pre-cooled in the three-stream heat exchanger 1 and directly sent to the propane external cooling evaporator 4 through the first bypass line 20 of the air cooler 3 for refrigeration 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.

[0038] In the present invention, unless otherwise specified, the equipment and devices used are all publicly known equipment and devices in the art, such as the three-stream heat exchanger 1, the gas-liquid separator 2, the air cooler 3, the propane external cooling evaporator 4 and the low-temperature separator 5.

[0039] As needed, the pipelines and equipment of the device for implementing the low-energy dew point control method for gas storage can also be equipped with conventional valves, thermometers, pressure gauges, etc. that are well known and used in the art according to production needs.

[0040] Example 11: The gas production period at a gas storage facility in northern China begins on November 20th of each year and ends on March 10th of the following year. Over the past 10 years, the ambient temperature in this region has ranged from -17°C to 2°C from November 20th to December 10th; 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.

[0041] November 20 to February 20:

[0042] Gas production volume 1440×10 4 m 3 / d, with a gas inlet pressure of 10.5 MPa and a temperature of 25°C to 35°C. The fourth valve 21, fifth valve 24, and sixth valve 25 are closed, and the first valve 17, second valve 18, and third valve 19 are open. After the raw gas enters the station, it passes through gas-liquid separator 2 to separate free liquids carried by underground produced gas. It is then pre-cooled to -5°C to 0°C in three-stream heat exchanger 1 before entering air cooler 3, where it is cooled to -10°C to -5°C due to the air enthalpy difference. After the condensed liquid is separated in low-temperature separator 5, the low-temperature dry gas is reheated to 20°C to 30°C in three-stream heat exchanger 1 for external transmission. The hydrocarbon water dew point of the exported gas is ≤0°C, meeting the requirements for natural gas transfer in the current standard "Natural Gas" GB 17820-2018, which stipulates that at the pressure and temperature conditions at the transfer point (ground temperature t ≥ 0°C), the natural gas should contain no liquid water or liquid hydrocarbons. During the period when the daytime temperature is above -10℃ (approximately 2 to 3 hours), the propane refrigeration system operates at a low load, further cooling the air-cooled natural gas to -10 to -5℃ for low-temperature separation. During the other periods, the propane external cooling system is on standby and air-cooled by air cooler 3.

[0043] From February 20 to March 10 of the following year, the gas production volume 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 to be reheated to 30℃ to 40℃ for external transmission. The hydrocarbon water dew point of the exported gas is ≤ 0°C, meeting the requirements for natural gas transfer in the current "Natural Gas" standard GB 17820-2018. This means that under the pressure and temperature conditions at the transfer point (ground temperature t ≥ 0°C), liquid water and liquid hydrocarbons should be absent. At the end of gas production, due to the high temperature of the incoming feed gas and the high saturated water content of the natural gas, air cooling can be performed through the second bypass line 22 and the third bypass line 23 before gas-liquid separation, pre-cooling in the three-stream heat exchanger 1, propane refrigeration, low-temperature separation, and reheating for external transmission.

[0044] In Example 11 of the present invention, the energy consumption of treating 10,000 cubic meters of produced gas in a gas storage facility in the north is approximately 1.76 kgce, which is about 46.8% lower than the energy consumption of conventional propane refrigeration dew point control process and reduces carbon emissions by about 8.4 kg CO2 / 10 4 m 3Compared with the throttling and pressure reduction low temperature separation dehydration and dehydrogenation + pressurized external transmission process, the energy consumption is reduced by about 68.3%, and the carbon emissions are 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.

[0045] In summary, the present invention combines the characteristics of the injection and production cycle of the gas storage reservoir, conducts a statistical analysis of climate change in the region where the gas storage reservoir is located through big data, and through technical and economic analysis, fully utilizes the coldness of the northern winter environment and adopts a low-temperature dehydration and dehydrogenation process combining air enthalpy difference refrigeration + propane auxiliary refrigeration to achieve the goals of energy conservation, carbon reduction, and cost reduction.

[0046] 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 removed according to actual needs to meet the requirements of different situations.

Claims

1. A low-energy dew point control method for a gas storage facility, characterized in that The following steps are followed: First, after the raw gas enters the station, the raw gas is separated into gas and liquid according to the temperature value when the raw gas enters the station, and the first mixed liquid phase and wet natural gas are obtained respectively. Among them, when the temperature of the raw gas entering the station is 25℃ to 35℃, the raw gas is directly transported to the gas-liquid separator for gas-liquid separation. When the temperature of the raw gas entering the station is higher than 35℃, it will be first transported to the air cooler after entering the station. After being cooled by air to a temperature of 25℃ to 35℃, the raw gas will be transported to the gas-liquid separator for gas-liquid separation. 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 pre-cooled by reverse heat exchange with the low-temperature dry gas from bottom to top after separation from the low-temperature gas, thereby obtaining pre-cooled wet natural gas. The fifth step is to obtain low-temperature wet natural gas after pre-cooling wet natural gas and refrigerating it again. Among them, when the pre-cooled wet natural gas is cooled again, based on the control process in the first step when the temperature of the raw gas entering the station is 25℃ to 35℃, the pre-cooled wet natural gas is cooled to a temperature of -10℃ to -5℃ by the air enthalpy difference of the air cooler to obtain low-temperature wet natural gas. Based on the control process in the first step when the temperature of the raw gas entering the station is higher than 35°C, 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 the propane external cooling evaporator 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 dew point control method for gas storage according to claim 1 is 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.

3. A device for implementing the low-energy dew point control method for a gas storage facility according to claim 1 or 2, 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 to the raw gas inlet pipeline, the bottom outlet of the gas-liquid separator is fixedly connected to the 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 to the 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 to the pre-cooled wet natural gas outlet pipeline, the air cooler outlet and the inlet of the propane external cooling evaporator are fixedly connected to the low-temperature wet natural gas inlet pipeline, 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, the second lower outlet of the three-stream heat exchanger is fixedly connected to the second mixed liquid phase discharge pipeline, and the second upper inlet of the three-stream heat exchanger is fixedly connected to the ethylene glycol injection pipeline.

4. The device according to claim 3, 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.

5. The device according to claim 3 or 4, characterized in that A first bypass pipeline is fixedly connected between the pre-cooling 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.

6. The device according to claim 5, 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-cooled 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. The second bypass pipeline is fixedly connected with a fifth valve, and the third bypass pipeline is fixedly installed with a sixth valve.

Images