Answer questions of common problems in LNG gas station

 1.LNG what is the density of the liquid, is it constant, and what is the density of the vaporization?

Answer: LNG liquid density at -162.12 DEG C when the pressure is 0MPa, the density of 0.426 Kg /M3, which will change with the temperature, methane content and pressure of the liquid, when the temperature or pressure reduction, the density will be reduced, usually at a temperature of -124 DEG C, pressure 0.85MPa, liquid at around 0.35. The density of natural gas is at 0 C, 101.352Kpa is 0.7174Kg/Nm

2. thermostat, and EAG, what are they each?

Answer: the thermostat is the vaporizer, and its function is to increase the temperature of the LNG liquid. EAG is also a vaporizer. It is specially designed for heating the discharge system, heating and gasifying the discharged liquid or gas-liquid mixture, making the specific gravity less than the atmosphere and not sinking, so as to avoid safety accidents or hurting people when they are released.

3. the lower the temperature is, the better the temperature of the liquid I need. Why do we need to increase the temperature of the liquid?

Answer: there are some liquefaction plant liquefaction LNG temperature is very low, into the tank after unloading up to -152 DEG C, filling into the car's gas, automobile in use, because the automobile carburetor is relatively small, not enough to LNG evaporation vaporization of the liquid is very low, after vaporization may cause the temperature is very low, or some the residual liquid, into the engine, causing the power of the engine, greatly increase gas consumption. When the liquid in the tank is warming up in advance, these problems will be solved.

4. how to distinguish between BOG and EAG?

Answer: BOG, due to the daily evaporation rate of LNG in cryogenic storage tank and cryogenic tank car (about 0.3% or less), this part of evaporating gas (low temperature) is called BOG for short, so that the pressure of gas phase space increases. In order to ensure the safety of tanks and the need of loading and unloading cars, a safety and pressure relief valve is set up in the design. It can automatically exclude BOG according to the pressure during storage tanks. The BOG gas generated by heating the vent valve to the BOG heater and then enter the BOG storage tank. The cryogenic system of EAG cryogenic system is all low temperature gas. When the temperature is below -107 C, the natural gas is much heavier than the air at normal temperature. The emission is not easy to spread, and it will accumulate downwards and cause potential safety hazard. Therefore, an air temperature diffuser heater is set up. After discharging the gas through the heater, the specific gravity of the natural gas after air exchange will be less than that of the air. After the high point is released, it will spread easily, so that it is not easy to form explosive mixture.

In 5. tank, how much is the temperature of LNG liquid best?

Answer: if the liquid station operation is more normal, the temperature of the tank liquid is kept at -132 C, and the pressure is about 0.65MPa best.

How much is the flow of the 6. standard pry in the pump?

Answer: the standard prized American ACD pump is TC34, and the flow is 340L/ minutes.

When the pressure of the LNG tank in the 7.lng gasification station rises to how high, it begins to discharge pressure?

Answer: the design pressure of the general LNG storage tank is 1.6MPa, and the highest working pressure is 1.2MPa. In order to minimize the times of the safety valve beating, it is best to discharge the pressure when the tank pressure rises to 1MPa.

8. what is the principle of supercharger for turbocharging?

Answer: the liquid characteristic ratio of LNG is 1:625, that is to say, 1M3 will produce 625M3 gas after liquid gasification, the volume will increase, and the pressure will also increase if the space is constant. Turbocharger is based on this principle to achieve supercharging. When LNG enters the supercharger, the supercharger absorbs the heat in the air, so that the liquid in the supercharger will be gasified and the volume will increase, and the pressure will increase in the storage tank.


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