Working principle and process characteristics of CNG filling station for compressed natural gas There are two operating modes in the domestic CNG filling station: the mother-child station operation mode and the standard station operation mode. This window will introduce the knowledge of CNG refueling stations one after another. Today, we mainly introduce the working principle and process characteristics of CNG refueling station: Operating principle After the natural gas from the pipeline is introduced into the station, it is filtered and metered (installed by the gas supply unit), and then enters the low-pressure dehydration unit to remove the water, so that the dew point is at or below the national automobile standard (ie, the standard state). Down -55 ° C), then through the buffer into the natural gas compressor block. This system uses a skid-mounted compressor system to achieve gas compression, and manages the gas by prioritizing the control panel. The dry gas entering the skid-mounted compressor system, after multiple stages of pressurization, the pressure reaches 25Mpa. The interstage gas passes through the air cooler and the oil water separator and enters the next stage. The PLC (programmable controller) of the compressor system performs the whole process management of signal acquisition, fault diagnosis, fault display, priority order control, sequential start/stop, etc., and operates in an unattended automatic mode. The compressed high-pressure gas is filtered through the compressor, and then passed through the priority control panel to the gas storage well, the gas dispenser, and the gas addition column. The gas filling machine is used to refuel the natural gas vehicle, and the gas filling column is used to refuel the natural gas trailer. The gas storage wells are divided into three groups to achieve sequential gas supply to improve gas utilization, and a dual gun dispenser is also provided. The air dispenser can automatically refill the air, automatically close to the pressure, measure the display, and be equipped with an emergency shut-off valve. Process plan characteristics (1) Inbound safety shut-off system: An emergency shut-off valve is installed on the inbound natural gas pipeline, and a high-efficiency filter is provided after the shut-off valve. (2) Dehydration regeneration system: According to the raw material gas purification treatment, the raw natural gas is only subjected to simple separation of oil and gas at room temperature during the production process. Therefore, the saturated water content of the raw material gas under working conditions exists. The natural gas containing low-pressure saturated water is pressurized to 25 MPa, which will form part of free water and saturated water under working conditions; free water and heavy hydrocarbons will be separated and separated by compressor separation; pressure is 25.0 MPa, temperature is 45 °C The saturated water content still does not meet the requirements of CNG automotive gas dew point, so the raw material gas must be dehydrated to remove saturated water, further reduce the natural gas dew point, so that it is less than -55 ° C (dew point under the standard state), to meet the CNG inflation temperament requirements, It also provides a guarantee for the operation of the substation. The dehydration process in the gas station uses a molecular sieve adsorbent. The natural gas dehydration unit is placed in front of the compressor, and the natural gas enters the dehydration unit to remove free water and oil. Natural gas regeneration is required after the dryer packing is saturated. In order to avoid waste, the regeneration gas of the dehydration unit is obtained from the raw material natural gas. (3) Natural gas aqueous analysis system: an online micro-water analyzer is installed after the dewatering device to monitor the water content in the finished gas in real time. The secondary instrument is set in the control room. If the dew point is higher than -55 °C, the dehydration device must be switched. . (4) Pressure regulating system: Considering that the air pressure of the gas from the gas station will fluctuate according to the different gas volume, in order to ensure the compressor inlet pressure is stable, the compressor can work as much as possible at its optimal design point. Set of pressure regulating system. (5) Total station safety monitoring system: In addition to the safety protection of the system air pressure, oil pressure, temperature, vibration and overload automatically controlled by PLC, the system is equipped with multi-point reliable overpressure natural gas discharge device; The requirements of GB50156-2002 are arranged with a combustible gas alarm and cutting device controlled by PLC. The device forms a locked relationship with the power supply and air supply system, and can automatically cut off the intake and supply of the compressor. According to the needs of users, the above monitoring points can be connected to the computer to form a computer remote centralized monitoring system. (7) Safety relief of high-pressure pipelines and equipment: The safety relief pressure natural gas of all levels of the compressor system is concentrated and discharged outside the compressor room; the natural gas discharge from the gas storage tank is discharged and discharged in the sewage tank. (8) Exhaust gas recovery system: The compressor system discharges natural gas into the exhaust gas recovery tank, and a high-efficiency filter separation device is arranged in the exhaust gas recovery tank to separate the oil and water contained in the sewage gas, and the oil water is deposited at the bottom of the tank. Natural gas enters the compressor intake duct from the top to protect the environment and reduce waste. (9) In the configuration of the gas station device, the computer operation management system can also be provided according to the user's requirements to meet the marketing management requirements of the user's multiple modes. We recommend using the MICHELL Natural Gas Dew Point Detection Method for 24-hour on-line monitoring of water dew point values ​​in CNG. Concerned about surprises Label: Working principle and process characteristics of CNG filling station for compressed natural gas Previous: Analysis of advantages and disadvantages of electromagnetic flowmeter Next: Working process and principle of cooling tower Squeegee,Window Squeegee,quality scraper PRO-CHARGER CO., LTD. (VICTOR HERO HOLDINGS LTD, TIME VALUE LTD.) , https://www.pro-chargerco.com
(6) Automatic control system: The CNG filling station equipment is operated in a flammable, explosive, high-pressure and heavy-load working environment. The level of automation of the device directly determines the economic operation index of the system and the reliability of safe operation. Therefore, the compressor system implements highly automated control management, with programmable controller PLC as the core, adopting motor soft start, closed pressure relief and no load start; system oil pressure, current, temperature and air pressure automatic monitoring; automatic sewage system; Multi-block operation automatic authorization start; computer-controlled economic operation control system; PLC automatic sequential air supply control system; automatic temperature compensation and gas sales safety device. 
Working principle and process characteristics of CNG filling station for compressed natural gas