LNG Fueling Station Process
The process of LNG vehicle refueling stations consists of four stages: unloading process, pressure regulating process, refueling process, and pressure release process.
1. Unloading Process
There are three methods for transferring LNG from tanker trucks or containers to the LNG storage tanks at a gas station: turbocharger unloading, low-temperature pump unloading, and combined unloading using both a turbocharger and a low-temperature pump.
1) Turbocharger unloading: After unloading, the tank car needs to be depressurized by 0.2 to 0.3 MPa, which requires the release of a large volume of gas, taking a considerable amount of time.
2) LNG tank trucks and storage tanks are connected to the gas phase space, which is transported to the storage tank through low-temperature pumps. Disadvantages: High energy consumption, complex process flow.
3) Combined unloading of turbochargers and low-temperature pumps: First, connect the gas phase space of the LNG tank truck and storage tank, then disconnect. During the unloading process, use the turbocharger to moderately increase the pressure of the tank truck, and use the low-temperature pump to transfer LNG to the storage tank. Disadvantages of 30, 60, and 100 cubic meter LNG storage tanks: They consume electricity, produce vented gases, and have complex processes.
More often use the second method for unloading.
2. Pressure Regulation Process
The pressure inside the vehicle's gas cylinder is relatively high, typically ranging from 0.5 to 0.8 MPa. However, for transportation and storage, lower pressure is preferable. Therefore, before refueling a car, the tank needs to be pressurized. There are three methods: using a booster to increase pressure, using a pump for low-speed circulation to increase pressure, and combining both a booster and a pump for low-speed circulation to increase pressure.
3. Aerated process
After being pressurized by a low-temperature pump, the gas is metered and then filled into the vehicle's gas cylinders by a gas-filling machine, available in both single-line and dual-line configurations.
When the vehicle-mounted cylinder pressure is low, use the overhead sprinkling method to reduce pressure and decrease emissions.
When the pressure of the vehicle-mounted gas cylinder is high, a dual-line filling method is used, and the gas inside the cylinder is recycled back into the storage tank.
4. Pressure Relief Procedure
Excess pressure is released by the safety valve.
．Key equipment for LNG vehicle refueling stations
LNG Tank
Internal pressure design
External irrigation working temperature
Ambient Temperature
External irrigation design pressure
-0.1MPa
Effective Volume
Internal灌 pressure
0.45～0.8MPa
Filling Rate
90%
External irrigation working pressure
-0.1MPa
Evaporation Rate
Internal灌design temperature
-196℃
Infill Material
External irrigation design temperature
-19～50℃
External irrigation material
In-line filling operating temperature
-146℃
2. Low-temperature pump
Operating Temperature
-146℃
Design Head
220m
Design Temperature
-196℃
Maximum Head
255m
Design Flow
L/min
Required Net Positive吸入 Head
0.7～3.0m
2. Truck Unloading Turbocharger, Tank Turbocharger
Single-unit processing capacity
M3/h
Highest working pressure
0.8MPa
Imported Temperature
-162℃
Design Pressure
1.6MPa
Export Temperature
-146℃
Design Temperature
-196℃
3. Gas generator
Minimum nozzle pressure
0.41 MPa
Operating Temperature
-146℃
Traffic
0.15 cu/m/min
Measurement Accuracy
+0.5～-0.5%
Hose configuration
Single Tube
