LNG gasification station equipment configuration
1. LNG storage tank
The storage tank is the main equipment of the LNG gasification station, which directly affects the normal production of the gasification station. Existing vacuum powder insulation storage tanks, positive pressure accumulation insulation storage tanks and high vacuum layer insulation storage tanks, medium and small gasification stations generally use vacuum powder insulation low temperature storage tanks. The storage tank is divided into inner and outer layers, and the interlayer is filled with pearlescent sand and evacuated to reduce the introduction of external heat and ensure that the daily gasification rate of LNG in the tank is lower than 0.3%.
2. Self-pressurized gasifier
It is divided into unloading pressurized vaporizer and storage tank pressurized vaporizer, which are respectively used to pressurize the tanker storage tank when unloading and pressurize the LNG storage tank when discharging. For the design of the storage tank pressurized vaporizer, one LNG storage tank with one pressurized vaporizer is usually used. It is also possible to share one or one group of gasifiers for multiple storage tanks to pressurize. Through valve switching, the process can be simplified, equipment and cost can be reduced.
3. Air temperature vaporizer
Air temperature gasifier is the main gasification facility for LNG gasification station to supply gas to the city. After the low temperature liquid of the gasifier is continuously gasified from bottom to top, the gaseous medium flows out from the top. The symmetrical design of the pipeline ensures the uniform flow of the liquid in the vaporizer. Various types of vaporizers have different fin combinations. The powerful combination of fins is to reduce the frosting of the vaporizer and ensure vaporization. efficiency.
The gasification capacity of the gasifier is determined according to the gas consumption in the peak hour, and there is a certain margin, usually 1.3 to 1.5 times the gas consumption in the peak hour. The gasification capacity of a single gasifier is calculated at 2000m3/h, 2 to 4 units are in a group, and 2 to 3 groups are designed to be used interchangeably. These designs are designed to improve the gasification capacity and efficiency of the equipment.
4. Water bath heater
When the ambient temperature is low and the gaseous natural gas temperature at the outlet of the air-temperature gasifier is lower than 5°C, a water-bath natural gas heater is connected in series behind the air-temperature gasifier to heat the gasified natural gas. The heating capacity of the heater is determined by 1.3 to 1.5 times the gas consumption during the peak hour.
5. Pressure regulating, metering and odorizing devices
The pressure regulating device is selected according to the scale of the LNG gasification station. Usually 2-way pressure regulating device is set up, and the pressure regulator is a self-operated pressure regulator with pilot and overpressure cut-off. The measurement adopts a turbine flowmeter to control the external exhaust volume. The odorant uses tetrahydrothiophene, and the odorant is powered by a diaphragm metering pump, and the odorant is injected into the gas pipeline according to the flow signal.
6. BOG heater and storage tank
The storage temperature of LNG is -163°C, that is, the temperature of BOG is about -163°C. In order to ensure the safety of equipment, BOG should be heated to 15°C. Since the largest amount of BOG in the station is recovered gas-phase natural gas after the unloading of the tanker, the design capacity of the BOG air temperature heater is calculated based on this.
Generally, the BOG air temperature heater is selected according to the number of tankers that can be simultaneously unloaded in the gasification station. Usually the heating capacity of BOG heater is 500～1000m3/h. When using the water bath type natural gas heater in winter, BOG is used as the fuel for the hot water boiler, and the other seasons are sent to the urban transmission and distribution network. If the user does not use continuous gas, a BOG storage tank needs to be set up for storage.
