LNG Vehicle Refueling Station Process
The LNG refueling station process is divided into four stages: unloading, pressure regulation, refueling, and pressure relief.
1. Unloading Process
There are three methods to transfer LNG from tanker trucks or containers into the LNG storage tanks at a fueling station: turbocharger unloading, low-temperature pump unloading, and combined unloading using both turbocharger and low-temperature pump.
1) Turbocharger unloading: After unloading, the tanker must be depressurized by 0.2 to 0.3 MPa, requiring the release of a large volume of gas, which takes 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 via 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 LNG storage tanks: They consume electricity, produce venting gases, and have complex processes.
More often use the second unloading method.
2. Pressure Regulation Process
The pressure inside the vehicle's gas cylinder is typically high, around 0.5 to 0.8 MPa. However, for transportation and storage, lower pressure is preferable. Therefore, before refueling the car, the tank needs to be pressurized. There are three methods: pressure increase with a booster, low-speed pump circulation for pressure increase, and combined pressure increase using a booster and a low-speed pump.
3. Aerated Process
After being pressurized by a low-temperature pump, the gas is metered and then filled into vehicle gas cylinders by a gas refueling machine, available in single and double-line configurations.
When the vehicle-mounted gas cylinder pressure is low, use an overhead spray method to reduce pressure and minimize emitted gases.
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 Process
Excess pressure is released through the safety valve.
LNG Vehicle Fueling Station Major Equipment
LNG Storage Tank
Internal灌设计Pressure
External irrigation operating 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℃
Internal filling material
External irrigation design temperature
-19～50℃
External灌Material
In-line filling working 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 Suction Head for Import
0.7～3.0m
2. Truck Unloader Turbocharger, Tank Turbocharger
Individual 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 cubic meters/minute
Measurement Accuracy
+0.5～-0.5%
Hose configuration
Single tube
