Up to now, the Jingbian gas field has installed emergency pneumatic shut-off valves in the pit and outbound areas of several gas gathering stations. The instrument air source is a nitrogen bottle filled with high-pressure nitrogen. The instrument wind of the emergency pneumatic cut-off valve of the gas gathering station exposes the problems of the live joint, the threaded thread, the shut-off valve body, the solenoid valve and the pressure-reducing valve seal ring parts frequently leaking due to the change of the ambient temperature during the operation, and the frequent replacement of the nitrogen bottle Increased production and maintenance costs of gas fields and workload of employees. If not replaced in time, there will be certain safety hazards in the production process. 2 Comparison of different instrument air supply sources The instrument wind source of Jingbian gas field gas gathering station is 0 6 0 8 M Pa nitrogen gas, as long as it meets the instrument wind source pressure in the station, it can be used as a gas supply source. Therefore, it is possible to use three types of gas sources: a nitrogen gas bottle, a micro air compressor, or a natural gas in a gas gathering station. 2 1 nitrogen bottle gas source (1) Nitrogen source gas supply process. The nitrogen bottle is used as the instrument air source in the station (ie, the power source), and the high pressure nitrogen of the bottle group is depressurized to 0 6 MPa through the gas supply main pipe pressure reducing valve, and the nitrogen gas after the pressure reduction is connected to the pit stop area and the outer transfer area through the pipeline. Pneumatic shut-off valve. (2) The disadvantage of a nitrogen bottle as a source of instrument air. According to the working principle of the emergency pneumatic shut-off valve, only nitrogen is consumed during opening and closing, and nitrogen is not consumed during operation. Field tests have found that the emergency pneumatic cut-off system has leaks, exposing problems such as live joints, threaded fasteners, shut-off valve bodies, solenoid valves and pressure-reducing valve seal components that are frequently leaked due to changes in ambient temperature. The gas station emergency pneumatic cut-off valve consumes too much nitrogen. The average 1 bottle of nitrogen can be used for 10 15 days. A few gas stations can use 1 bottle of nitrogen for 23 months. About 8 gas gathering stations can use only 1 bottle of nitrogen. 5 days. Frequent replacement of the nitrogen bottle increases the number of automatic/manual switching of the shut-off valve, resulting in increased shut-off valve failure and reduced service life, which in turn increases the operating and maintenance costs of the emergency pneumatic shut-off valve. (3) Solution. First, the interface between the instrument air line and the cut-off valve, solenoid valve and nitrogen source should be minimized, and the raw material belt should be sealed and wound to correct the leak point in time. For leaks that cannot be found in soap bubbles, use other leak detection methods, such as adding a tracer such as odorant or pigment to the instrument air source to find the dew point. Secondly, the plastic valve and the pressure reducing valve seal ring and other components are plastically deformed and damaged due to the working environment temperature, and the emergency pneumatic shut-off valve solenoid valve and the pressure reducing valve sealing ring member are re-selected. 2 2 micro air compressor air supply (1) Selection of micro air compressors. At present, there are three types of micro air compressors on the market: reciprocating, screw and centrifugal. Reciprocating compressors are more mature in domestic micro-machines and have lower costs. Each gas-gathering station is equipped with an external electric and fuel generator. Therefore, it is recommended to use an electric drive reciprocating air compressor. According to the investigation, the micro air compressor suitable for this station is classified into three types according to the exhaust volume: the displacement is 0 1 m 3 / min; the displacement is 0 2 m 3 / min; the displacement is 0 3 m 3 / min . (2) Gas supply process and technical requirements. The air enters the air compressor through the filter, and the compressed air passes through the cold dryer and enters the filter for filtration. The filtered air enters the air storage tank storage and enters the instrument air main pipe in the station. The principle of gas supply for the micro air compressor is similar to that of the nitrogen bottle. The compressed air is used as a gas supply source instead of nitrogen to supply air to the emergency pneumatic shut-off valve. The difference is when the air storage tank reaches a certain set pressure. The micro air compressor is automatically turned on and inflated to the gas storage tank. After a certain set pressure is reached, the micro air compressor is automatically turned off. The micro air compressor air supply system incorporates a cold dryer, a filter and a pressure reducing valve. The function is to condense and dry the compressed air, further filtering and adjusting the compressed air pressure. (3) Calculation of the theoretical opening frequency of the air compressor. It is known that the theoretical air consumption rate of the emergency pneumatic cut-off valve in the gas gathering station is 15 L / s, that is, 90 L of nitrogen per minute. Combined with the relevant performance parameters of the micro air compressor, the selected exhaust volume is 0 1 m 3 / Min's micro air compressor can meet the gas demand of the shut-off valve. Combined with the current use of the nitrogen cylinder of the emergency pneumatic cut-off valve in the Jingbian gas field gas gathering station, the theoretical opening frequency formula of the micro air compressor can be obtained. F = Q 1 24 Q 2 N where F is the theoretical opening frequency of the micro air compressor (h/ Q) is the gas consumption (L) when the pressure of the micro air compressor tank drops to 0 6 MPa; Q 2 is the gas consumption when the pressure of the nitrogen bottle drops from 12 5 MPa to 0 6 M Pa (L) N is the nitrogen cylinder life cycle (d). The minimum opening period of 1 bottle of nitrogen is 15 d, and the volume of the micro air compressor tank is at least 65 L. When the exhaust pressure is 15 MPa, the theoretical opening frequency of the micro air compressor is calculated as follows: F = Q 1 24 Q 2 N = (1 5- 0 6) 65 24(12 5 - 0 6) 40 15 = 44 6 (h/time) that the micro air compressor is turned on at least once every 44 6 h. (4) Advantages of the air compressor unit. First, compared with the nitrogen gas supply mode, the air supply mode of the micro air compressor has the advantages that the compressed air is low in cost, and the compressed air is inexhaustible, and the air supply to the emergency pneumatic shutoff valve can be continuously and continuously reduced. The workload has improved the work efficiency and solved the problem of increased operating costs caused by wind leakage in the station. Second, the theoretical opening frequency of the air compressor is low, avoiding frequent starts, reducing the failure rate of the moving equipment, and ensuring the stability of the instrument wind system in the gas gathering station. 2 3 Gas source in the gas gathering station (1) The natural gas in the station is used as the instrument air source process. The natural gas inside and outside the gas gathering station is used as the instrument air source, and the pressure regulator is added to the self-use gas pipeline in the outer transmission area, and the natural gas suitable for the instrument wind pressure is connected to the gas source main pipe. (2) The advantages of natural gas as an instrument air source. The advantages include: stable gas supply; steel pipe connection in the whole gas supply process is welded, reducing the union; the entire gas supply system has only installation cost and low operating cost; compared with the micro air compressor, no mechanical equipment maintenance is required. Technical support with maintenance and professional technicians. (3) The disadvantage of natural gas as an instrument air source. The shortcomings include: Natural gas is flammable and explosive gas, and the entire gas supply system can not guarantee zero leakage point. There is a safety hazard in the leakage of natural gas in the air; water and H 2 S in natural gas will corrode the emergency pneumatic shut-off valve for gas supply. system. 3 Economic Benefit Evaluation (1) Nitrogen bottle as the annual average operating cost of the gas source. Due to the air leakage problem in the instrument air system in the gas gathering station, the average nitrogen consumption period per bottle is only 15 days. According to the current price of nitrogen per bottle, 200 yuan (including transportation costs), the annual average operation of the gas gathering station is 320 days. The average annual operating cost of the gas source is 4,400 yuan. In order to strengthen the rectification of the wind leakage problem of the gas collection station, combined with effective management, the average cycle of nitrogen per bottle at the gas gathering station will increase. According to the use cycle of different nitrogen bottles, the annual average operating cost of the gas supply sources of different nitrogen bottles can be obtained. (2) Micro-air compressors as the average annual operating cost of the gas source. According to the current operation of the emergency pneumatic cut-off valve of the gas gathering station, the V - 0 1/ 15 explosion-proof micro air compressor can meet the operation of the emergency pneumatic cut-off valve. Increase the purchase cost of micro air compressor equipment by 8,700 yuan (including dryers, filters and other ancillary equipment), the cost of pipeline materials is 600 yuan, the construction cost is 2,000 yuan, and the annual average maintenance cost is 700 yuan (filters and other components), if micro The air compressor has a service life of 15 years, and the annual average operating cost is 1,220 yuan. (3) Annual average operating cost of self-contained gas supply source in gas gathering station. The cost of installing the natural gas instrument air source system in the gas gathering station is about 8,000 yuan (including the blasting instrument), mainly for one-time investment, and the daily gas consumption can be neglected. 4 Conclusion (1) Analyze the three instrument air sources of the above gas gathering stations. It can be considered that the three methods can provide a gas source for the instrument air system in the station continuously and steadily. (2) From the economic point of view, natural gas in the station is the most cost-effective source of instrumentation. (3) From the perspective of safety, environmental protection and economic integration, it is feasible to use the air source of the micro air compressor as the instrument air source of the gas gathering station. Aluminum Die Casting Hardware Parts Aluminum Die Casting Hardware Parts are a metal forming process in which molten aluminum metal is put under pressure and injected into a die. 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