A method for putting into operation of a first purification device for re-production of a high-sulfur gas field

Abstract

The present application relates to natural gas purification device field, specifically relates to a kind of high sulfur gas field first set of purification device's commissioning method of reproduction, by completing purification device overhaul, nitrogen gas tight test is qualified, utilize product gas to replace nitrogen in dehydration unit, can improve work efficiency;Since dehydration unit has replaced internal nitrogen in advance, after starting, the gas in dehydration unit does not need to be replaced again, when the gas quality of desulfurization unit meets the requirements and is connected to dehydration unit, can directly realize external transport, reduce the resource waste of venting process;Product gas is used to replace nitrogen, the whole process is airless, explosive mixed gas cannot be formed, can guarantee the safety of reproduction process.

Description

Technical Field

[0001] This invention relates to the field of natural gas purification equipment, and in particular to a method for commissioning the first purification unit in a high-sulfur gas field resuming production. Background Technology

[0002] The main function of natural gas purification units is to reduce the content of hydrogen sulfide, organic sulfur, and carbon dioxide in high-sulfur gases, ensuring they meet national requirements before being piped into the pipeline network. Purification units typically involve high pressure, toxic substances, and flammable and explosive conditions, requiring periodic shutdowns and maintenance to ensure they remain in good working order.

[0003] After the purification unit has been shut down for maintenance, in order to ensure a smooth, safe and efficient start-up process, the desulfurization unit and the dehydration unit of the purification unit need to undergo pressure testing. This is to prevent abnormalities caused by the accidental release of dangerous energy and materials during the start-up process. Currently, nitrogen is generally used to replace all the internal spaces after maintenance, replacing the original air with nitrogen, and then conducting an airtightness test. After the airtightness test is passed, nitrogen is used to maintain the pressure of the desulfurization and dehydration units within a normal working pressure range.

[0004] The existing nitrogen gas tightness and pressurization methods require continuous replacement of nitrogen in the original high-pressure zones of the desulfurization and dehydration units after the introduction of high-sulfurization gas to ensure that the exported product gas strictly meets national standards. All gases used in the replacement process are directed to the flare system. The continuous replacement process consists of two steps. The first step involves the raw material gas entering the desulfurization unit and being replaced through the wet purified gas vent valve. Only after successful replacement can the wet purified gas from the desulfurization unit enter the dehydration unit. Once in the dehydration unit, the nitrogen in the original dehydration system is replaced through the product gas vent valve. Only after successful replacement can the product gas be exported. The replacement process essentially transforms the nitrogen environment in both the desulfurization and dehydration systems to the conditions under normal production conditions, reducing the nitrogen content from over 98% to below 0.5%. However, the continuous replacement process using raw material gas results in a large amount of wet purified gas and purified gas entering the flare for combustion, causing significant waste and reducing operational efficiency.

[0005] Therefore, there is an urgent need for a technical solution to address the technical problem that the first purification unit used in the resumption of production of the original high-sulfur gas field adopts a feed gas replacement process, which results in a large waste of feed gas and low operating efficiency. Summary of the Invention

[0006] The purpose of this invention is to address the technical problem that the first purification unit used in the resumption of production of high-sulfur gas fields adopts a feed gas replacement process, resulting in a large waste of feed gas and low start-up efficiency. The invention provides a method for putting the first purification unit into operation when resuming production of high-sulfur gas fields.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution: A method for commissioning the first purification unit in a high-sulfur gas field regeneration project, applicable to the desulfurization and dehydration units of the purification unit, includes the following steps: S1: While keeping the desulfurization unit and the dehydration unit connected, close all inlet and outlet valves of the desulfurization unit and the dehydration unit; S2: Nitrogen gas is introduced to replace the air in the desulfurization unit and the dehydration unit. The displaced gas is sent to the flare system until the nitrogen content of the displaced gas is greater than 98% and the oxygen content is less than 0.5%. S3: Close the pipeline to the flare system, continue to fill the desulfurization unit and the dehydration unit with nitrogen, and conduct an airtightness test; S4: After the airtightness test is passed, the desulfurization unit and the dehydration unit are disconnected; S5: Introduce product gas to replace the nitrogen gas in the dehydration unit; S6: Introduce raw material gas to vent the desulfurization unit; S7: Connect the desulfurization unit and the dehydration unit, introduce the raw gas that has passed through the desulfurization unit into the dehydration unit, and incorporate the gas that has passed through the dehydration unit into the product gas pipeline network.

[0008] This invention discloses a method for commissioning the first purification unit for the resumption of production in a high-sulfur gas field. After the purification unit has undergone maintenance and passed the nitrogen tightness test, the nitrogen in the dehydration unit is replaced with product gas, which can improve the start-up efficiency. Since the nitrogen in the dehydration unit has been replaced in advance, the gas in the dehydration unit does not need to be replaced again after startup. When the gas quality of the desulfurization unit meets the requirements and is connected to the dehydration unit, it can be directly exported, reducing the waste of resources in the venting process. The replacement of nitrogen with product gas is air-free throughout the process, and no easily explosive mixed gas will be formed, ensuring the safety of the resumption process.

[0009] In a preferred embodiment of the present invention, the desulfurization unit and the dehydration unit are connected and disconnected via a shut-off valve. The shut-off valve allows for better control over the desulfurization and dehydration units.

[0010] In a preferred embodiment of the present invention, in S2, the nitrogen gas is introduced from the high-pressure nitrogen supply point of the desulfurization unit, and the displaced air is sent to the flare system through the wet purification gas vent valve and the product gas vent valve. Nitrogen gas is simultaneously introduced into both the desulfurization unit and the dehydration unit, thereby displacing the gas within both units.

[0011] As a preferred embodiment of the present invention, in S3, the conditions for passing the airtightness test include: after the internal pressure rises to 5.5 MPa, the pressure drop does not exceed 0.01 MPa every two hours. This ensures good airtightness of the desulfurization unit and the dehydration unit.

[0012] In a preferred embodiment of the present invention, in step S5, the pressure of the dehydration unit after gas replacement is consistent with the pressure of the product gas pipeline network. This restores the gas pressure of the dehydration unit to the normal operating pressure.

[0013] As a preferred embodiment of the present invention, S5 specifically includes: S5.1: Open the product gas vent valve to allow the gas in the dehydration unit to enter the flare system under pressure until the pressure in the dehydration unit remains at 0.2-0.3 MPa; S5.2: Close the product gas vent valve and open the dehydration unit outlet valve to allow the gas in the product gas pipeline to be introduced back into the dehydration unit through the product gas outlet valve to replace the gas in the dehydration unit. S5.3: Repeat S5.1-S5.2 until the nitrogen content of the displaced gas is less than 0.5% and the product gas content is greater than 98%.

[0014] Repeatedly vent the gas in the dehydration unit until the nitrogen content of the vented gas is less than 0.5% and the product gas content is greater than 98%, ensuring that the dehydration unit returns to normal working condition and avoiding the risk of start-up caused by air mixing.

[0015] As a preferred embodiment of the present invention, in S5.2, the gas introduced into the dehydration unit conforms to the national Class I gas standard, with a pressure rating of 4.0 MPa. This avoids the start-up risks caused by impure gas.

[0016] As a preferred embodiment of the present invention, in S6, the qualified standard for the venting of the desulfurization unit includes: the hydrogen sulfide content of the vented gas is less than 6 mg / m³. 3 The total sulfur content is less than 20 mg / m³. 3 To avoid the risks of starting operations due to impure gases.

[0017] In a preferred embodiment of the present invention, in S6, the raw material gas is produced from a gas well, and the hydrogen sulfide content of the raw material gas is 4.5%-5.5%.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The present invention provides a method for commissioning the first purification unit for the resumption of production in a high-sulfur gas field. After the purification unit has undergone maintenance and passed the nitrogen tightness test, the nitrogen in the dehydration unit is replaced with product gas, which can improve the start-up efficiency. Since the nitrogen in the dehydration unit has been replaced in advance, the gas in the dehydration unit does not need to be replaced again after startup. When the gas quality of the desulfurization unit meets the requirements and is connected to the dehydration unit, it can be directly exported, reducing the waste of resources in the venting process. The replacement of nitrogen with product gas is air-free throughout the process, and no easily explosive mixed gas will be formed, which can ensure the safety of the resumption process. 2. The present invention provides a method for commissioning the first purification unit for the resumption of production in a high-sulfur gas field, which shortens the commissioning time of the purification unit after maintenance, improves the start-up efficiency, and has good economic value. Attached image description: Figure 1 A simplified structural diagram of a purification device for the first purification unit in a high-sulfur gas field re-production project. Figure 2 A schematic diagram of the desulfurization unit structure of the first purification device for the resumption of production in a high-sulfur gas field; Figure 3 This is a schematic diagram of the dehydration unit structure of the first purification device for the resumption of production in a high-sulfur gas field.

[0019] Figure label: 1-High-pressure nitrogen replenishment point, 2-Wet purified gas vent valve, 3-Shut-off valve, 4-Product gas vent valve, 5-Product gas outlet valve, 6-Desulfurization unit, 7-Dehydration unit. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to experimental examples and specific embodiments. However, this should not be construed as limiting the scope of the above-mentioned subject matter of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0021] Example 1 A method for commissioning the first purification unit in a high-sulfur gas field regeneration facility, applicable to the desulfurization unit 6 and dehydration unit 7 of the purification unit, includes the following steps: S1: While keeping the desulfurization unit 6 and the dehydration unit 7 connected, close all inlet and outlet valves of the desulfurization unit 6 and the dehydration unit 7; S2: Nitrogen gas is introduced to replace the air in the desulfurization unit 6 and the dehydration unit 7. The displaced gas is sent to the flare system until the nitrogen content of the displaced gas is greater than 98% and the oxygen content is less than 0.5%. S3: Close the pipeline to the flare system, continue to fill the desulfurization unit 6 and the dehydration unit 7 with nitrogen, and conduct an airtightness test; S4: After the airtightness test is passed, the desulfurization unit 6 and the dehydration unit 7 are disconnected; S5: Introduce product gas to replace the nitrogen gas in the dehydration unit 7; S6: Introduce raw material gas to vent the desulfurization unit 6; S7: Connect the desulfurization unit 6 and the dehydration unit 7, introduce the raw gas that has passed through the desulfurization unit 6 into the dehydration unit 7, and incorporate the gas that has passed through the dehydration unit 7 into the product gas pipeline network.

[0022] Specifically, all contents in this embodiment are by volume.

[0023] Specifically, after completing the maintenance of the purification unit, this method is used as follows: First, all inlet and outlet valves of desulfurization unit 6 and dehydration unit 7 are closed, and desulfurization unit 6 and dehydration unit 7 are connected. High-pressure nitrogen replenishment point 1 is used to replace the gas in desulfurization unit 6 and dehydration unit 7. The replaced gas is sent to the flare system through wet purified gas vent valve 2 and product gas vent valve 4. When the nitrogen content of the discharged gas is greater than 98% and the oxygen content is less than 0.5%, the replacement is considered qualified. The replacement process is to ensure that no mixture of raw material gas and air is generated in the system after the introduction of raw material gas.

[0024] Specifically, after the nitrogen replacement is qualified, close the two valves, wet purification gas vent valve 2 and product gas vent valve 4, and continue to fill nitrogen into the desulfurization unit 6 and dehydration unit 7 through the high-pressure nitrogen replenishment point 1 to increase the pressure in the desulfurization unit 6 and dehydration unit 7, and complete the airtightness check of the desulfurization unit 6 and dehydration unit 7.

[0025] Specifically, after the airtightness check is passed, the shut-off valve 3 between the desulfurization unit 6 and the dehydration unit 7 is closed. Product gas is then introduced into the dehydration unit 7 through the product gas outlet valve 5, and the gas inside the dehydration unit 7 is discharged through the product gas vent valve 4. By using the pressure charging and depressurization method, the nitrogen in the dehydration unit 7 is replaced until the nitrogen content of the discharged gas is less than 0.5% and the fuel gas content is greater than 98%. Finally, the dehydration unit 7 is filled with product gas, and the internal pressure of the dehydration unit 7 is basically the same as the pressure of the product gas pipeline network.

[0026] Specifically, since the desulfurization unit still maintains a nitrogen-controlled pressure environment, to ensure that the gas meets national quality standards, the nitrogen in desulfurization unit 6 needs to be vented when the purification unit starts up with high-sulfur natural gas. In this embodiment, the method used is to replace the nitrogen with raw material gas. Specifically, while the purification unit introduces high-sulfur natural gas, desulfurization unit 6 is vented from wet purified gas vent valve 2. Once the quality of the vented gas meets the requirements, shut-off valve 3 is opened, and the raw material gas that has passed through desulfurization unit 6 is introduced into dehydration unit 7. The qualified standards for the gas discharged from wet purified gas vent valve 2 include hydrogen sulfide less than 6 mg / m3 and total sulfur content less than 20 mg / m3.

[0027] Specifically, the airtightness qualification means that the internal pressure of the desulfurization unit and the dehydration unit can rise to each pressure stage and maintain pressure stability after nitrogen replenishment is stopped. The airtightness test needs to complete a test at a maximum level of 5.5 MPa.

[0028] Specifically, since the raw material gas replacement was completed inside the dehydration unit 7 before the resumption of production, and the pressure environment inside is maintained by the product gas, there is no need to replace it again. Therefore, when the raw material gas from the desulfurization unit 6 is introduced into the dehydration unit 7, the product gas outlet valve 5 of the dehydration unit 7 can be opened to directly connect the dehydrated gas into the pipeline network. The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for commissioning the first purification unit for the resumption of production in a high-sulfur gas field, characterized in that, Applicable to the desulfurization unit (6) and dehydration unit (7) of the purification device, including the following steps: S1: While keeping the desulfurization unit (6) and the dehydration unit (7) connected, close all inlet and outlet valves of the desulfurization unit (6) and the dehydration unit (7); S2: Nitrogen gas is introduced to replace the air in the desulfurization unit (6) and the dehydration unit (7). The replaced gas is sent to the flare system until the nitrogen content of the replaced gas is greater than 98% and the oxygen content is less than 0.5%. S3: Close the pipeline to the flare system, continue to fill the desulfurization unit (6) and the dehydration unit (7) with nitrogen, and conduct an airtightness test; S4: After the air tightness test is passed, the desulfurization unit (6) and the dehydration unit (7) are disconnected. S5: Introduce product gas to replace the nitrogen in the dehydration unit (7); introduce product gas into the dehydration unit (7) through the product gas outlet valve (5), and then discharge the gas in the dehydration unit (7) through the product gas vent valve (4); specifically including: S5.1: Open the product gas vent valve (4) to allow the gas in the dehydration unit (7) to enter the flare system under pressure until the pressure in the dehydration unit (7) is 0.2-0.3 MPa. S5.2: Close the product gas vent valve (4) and open the product gas outlet valve (5) so that the gas in the product gas pipeline is introduced into the dehydration unit (7) in reverse through the product gas outlet valve (5) to replace the gas in the dehydration unit (7); S5.3: Repeat steps S5.1-S5.2 until the nitrogen content of the displaced gas is less than 0.5% and the product gas content is greater than 98%; S6: Introduce raw gas to vent the desulfurization unit (6); while introducing high sulfur natural gas, vent the desulfurization unit (6) from the wet purified gas vent valve (2); S7: Connect the desulfurization unit (6) and the dehydration unit (7), introduce the raw gas that has passed through the desulfurization unit (6) into the dehydration unit (7), and incorporate the gas that has passed through the dehydration unit (7) into the product gas pipeline.

2. The method for commissioning the first purification unit for the resumption of production in a high-sulfur gas field as described in claim 1, characterized in that, The desulfurization unit (6) and the dehydration unit (7) are connected and disconnected by a shut-off valve (3).

3. The method for commissioning the first purification unit for the resumption of production in a high-sulfur gas field as described in claim 2, characterized in that, In step S7, when the quality of the vented gas meets the requirements, the shut-off valve (3) is opened to introduce the raw gas that has passed through the desulfurization unit (6) into the dehydration unit (7).

4. The method for commissioning the first purification unit for the resumption of production in a high-sulfur gas field as described in claim 1, characterized in that, In S2, the nitrogen gas is introduced from the high-pressure nitrogen gas replenishment point (1) of the desulfurization unit (6), and the displaced air is sent to the flare system through the wet purification gas vent valve (2) and the product gas vent valve (4).

5. The method for commissioning the first purification unit for the resumption of production in a high-sulfur gas field as described in claim 1, characterized in that, In S3, the conditions for passing the airtightness test include: after the internal pressure rises to 5.5 MPa, the pressure drop does not exceed 0.01 MPa every two hours.

6. The method for commissioning the first purification unit for the resumption of production in a high-sulfur gas field as described in claim 1, characterized in that, In S5, the pressure of the dehydration unit (7) after gas replacement is consistent with the pressure of the product gas pipeline.

7. The method for commissioning the first purification unit for the resumption of production in a high-sulfur gas field as described in claim 1, characterized in that, In S5.2, the gas introduced into the dehydration unit (7) meets the national Class I gas standard and has a pressure rating of 4.0 MPa.

8. The method for commissioning the first purification unit for the resumption of production in a high-sulfur gas field as described in claim 1, characterized in that, In S6, the qualified standards for the venting of the desulfurization unit (6) include: the hydrogen sulfide content of the vented gas is less than 6 mg / m3, and the total sulfur content is less than 20 mg / m3.

9. The method for commissioning the first purification unit for the resumption of production in a high-sulfur gas field as described in claim 1, characterized in that, In S6, the raw gas is produced from a gas well, and the hydrogen sulfide content of the raw gas is 4.5%-5.5%.

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