Product Introduction:
Liquefied Natural Gas (LNG) is a low-temperature liquid formed by purifying and cooling natural gas to approximately -162ºC. BOG, short for boil-off gas, refers to the flash vapor produced when LNG absorbs external heat and vaporizes.
Currently, there is an issue with incomplete unloading of LNG tank trucks at refueling stations in China, especially concerning the remaining BOG gas inside the trucks, which cannot be unloaded into storage tanks as intended. LNG refueling stations use LNG pumps or LNG boosters, or a combination of both. When unloading with LNG pumps, only the LNG liquid can be pumped out, while the BOG gas remains at a high pressure and low temperature inside the truck after unloading is completed. When unloading with self-boosters, a significant amount of BOG gas also remains inside the truck after the liquid is unloaded. In order to ensure vehicle operation safety, facilitate the next loading operation, and reduce vehicle weight to meet the user's verification of the quantity transported, truck drivers often release BOG gas into the atmosphere after unloading, which not only increases the risks but also leads to losses for users and resource wastage, as well as environmental pollution.
Furthermore, in LNG refueling station storage tanks, due to the absorption of external heat, a portion of LNG gasifies into BOG gas. When the amount of BOG gas increases to a level that exceeds the design safety pressure of the tank, the tank's safety valve opens to release BOG gas to the outside, resulting in resource wastage. Therefore, there is an urgent market need for equipment that can recover BOG gas from tank trucks and storage tanks.
Our company has conducted research and development on BOG recovery equipment to effectively address the inability to recover BOG gas from LNG tank trucks and the overpressure BOG discharge from LNG refueling station storage tanks. The BOG recovery equipment serves the functions of unloading and loading LNG, as well as recovering BOG. It consists of a low-temperature explosion-proof compressor, a cold energy recovery system, a pressure control and protection system, pipelines, and other components.
Internal Structure Diagram:
1,Heat Exchanger
2,PLC Electrical Control System
3,Inlet Pressure Gauge
4,Outlet Pressure Gauge
5,Inlet Shut-off Valve
6,Outlet Shut-off Valve
7,Inlet Flange
8,Outlet Flange
9,Inlet Inspection Valve
10,Oil Injection Port
11,Oil Level Sight Glass
12,Compressor
(Note: If the displayed diagram differs from the actual equipment, refer to the labeling onthe actual equipment as the primary reference.)
BOG Recovery Machine Operation Steps:
Connection of Pipelines: Connect the BOG recovery machine's inlet with the vapor phase outlet of the tank truck using a DN50 flexible hose. Connect the outlet of the BOG recovery machine with the liquid phase inlet (downward liquid inlet) of the storage tank.
Pipeline Purging: After accurately connecting the hoses, perform a purge of the hoses (ensure purging is done before each operation). Open the tank truck vapor phase shut-off valve J04, the recovery machine inlet shut-off valve H01, the recovery machine outlet shut-off valve H02, and the vent valve. Start the compressor to purge the pipelines. After purging, close the vent valve (bypass vent valve next to J03) and open the storage tank liquid inlet valve J03.
BOG Recovery: After purging, close the vent valve and open the storage tank liquid inlet J03. Observe the pressure indications on the inlet and outlet pressure gauges of the recovery machine to ensure they meet the compressor start conditions (0.2 MPa < inlet pressure ≤ 0.7 MPa, outlet pressure ≤ 1.0 MPa). If conditions are met, turn on the emergency stop button and then turn the rotary switch from "0" to "I" position, which activates the BOG recovery mode (strictly prohibited: the "II" option for unloading mode must not be enabled, any violation resulting in equipment damage or other special circumstances will be the responsibility of the user). Press the green start button once, and the compressor will start automatically. After starting, adjust the ball valve between the oil-gas filter and the compressor to ensure the compressor oil level is maintained at the standard level, not too high or too low. When the tank truck pressure reaches the set value, the compressor will automatically shut down for self-lock protection. Finally, press the emergency stop switch to end the BOG recovery process. During equipment operation, if a shutdown is required
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