LNG station issues
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1. LNG tankers are used to supply gas temporarily to the boiler room. There are no flow meters either on the LNG tankers or on the boilers. The LNG tankers have a capacity of 50 cubic meters, and each tanker weighs 20 tons. The boiler can handle up to 130 cubic meters of gas at a time (they mentioned cubic feet, but I’m not sure if that refers to cubic meters). How many days can the LNG tankers supply gas to the boiler? List the specific formulas and how to calculate them. 2. A problem arose during LNG unloading; I discussed it with my colleagues (usually, liquid is introduced from the top of the tank to cool the gas inside, thereby reducing the pressure in the tank) ； However, when the pressure-boosting setting is turned off during the unloading of LNG from the tank truck, and both the bottom inlet and the top inlet are opened while connecting to the air-temperature vaporizer, the pressure inside the tank truck keeps rising; the safety valve keeps activating. There is a one-way valve at the top inlet, and it seems that the liquid from the bottom outlet goes in two directions: one path leads to the vaporizer, while the other path returns to the tank truck through the top inlet ； I previously explained that allowing liquid to enter from the top could cool the gas, facilitating its liquefaction and thus reducing pressure. But now the tank truck keeps experiencing increased pressure, so that explanation no longer holds. Let’s discuss this together
It’s a very practical issue; it’s something that our production department is concerned about. Please, those with experience, reply! !
A 20T tank truck usually has a capacity of 56 cubic meters; we refer to it as 60 cubic meters. 130 cubic meters probably refers to the hourly flow rate. If that’s the case, it’s also necessary to know how many hours it operates. For example, if gas is used for 8 hours per day, the daily consumption would be 130*8. Converting this to weight gives 130*8/1.4, where 1.4 is the vaporization rate. The actual value should be based on the gas quality report provided by the supplier. That’s the amount used per day. It can be determined how many days the 20T tank can be used. The inflow of liquid can cause the gaseous portion in the tank to liquefy. Indeed, when the pressure booster vaporizer increases pressure, gas is produced and sent back to the upper part of the tank; as a result, the gas inside the tank does not liquefy. Therefore, the pressure in the tank only increases. I’m not sure if my understanding is correct; please feel free to give me your feedback
20 tons should refer to the weight (mass) of liquid LNG. Typically, this is 1400 NM3 per ton (this value can vary depending on the raw gas used; the supplier usually provides this information). Therefore, 20 tons equates to 28,000 NM3. If the 130 cubic meters you mentioned refers to the hourly or daily gas consumption, a simple calculation will yield the result. For the second question, it would be better if it were described more clearly