Liquefying system and method of propane boil off gas (BOG) and butane BOG

Abstract

The invention relates to a liquefying system and method of propane boil off gas (BOG) and butane BOG. The system comprises a gas liquid separation tank, a propane BOG output tube for transferring the propane BOG to the gas liquid separation tank, a compressor for compressing the propane BOG, a propane liquefier for liquefying high-pressure propane BOG, a propane buffer tank and a propane gathering tank respectively for temporally storing and collecting the high-pressure liquid propane, a propane spherical tank for storing low-pressure liquid propane, a propane conveying pipe communicated with the propane gathering tank and the propane spherical tank, a propane regulating valve arranged on the propane conveying pipe, a butane condenser for liquefying the butane BOG, a butane liquefying cold energy conveying pipe for providing the liquid propane serving as liquefying cold energy for the butane condenser, a depressurizing throttling valve arranged on the butane liquefying cold energy conveying pipe, a butane buffer tank for temporally storing the liquid butane, a butane return pump for transferring normal-pressure liquid butane to a butane storage tank, and a butane liquid pump coupled to the liquid space of the propane gas liquid separation tank and used for providing power for the liquid butane therein and sending to the butane storage tank. The liquefying system provided by the invention has the advantages of improving liquification and the outer input comprehensive energy utilization rate.

Description

technical field [0001] The invention relates to the field of storage and delivery of low-temperature liquefied petroleum gas, in particular to a liquefaction system and method for propane boil-off gas and butane boil-off gas. Background technique [0002] Liquefied Petroleum Gas (LPG) is a mixture of propane and butane. Propane is a three-carbon alkane that is usually gaseous. Butane is a general term for two alkane hydrocarbons with the same molecular formula (C4H10), including n-butane and isobutane. [0003] Propane and butane are generally stored in their respective storage tanks in a low-temperature micro-positive pressure liquid phase. Since both propane and butane in the low-temperature liquid phase absorb heat in the environment, the part above the liquid level in the storage tank is caused by low temperature The gas phase space formed by the boil-off gas (BOG) of propane or butane. With the increase of BOG, the air pressure in the storage tank will gradually incr...

AI Technical Summary

Problems solved by technology

It can be seen that since the existing technology uses two independent systems for the liquefaction of propane BOG and butane BOG, a certain amount of energy needs to be consumed when liquefying propane BOG and butane BOG with higher temperatures. At the same time, it is also necessary to heat the lower temperature liquid propane, which also consumes a certain amount of energy

Therefore, the existing liquefaction technology results in a relatively low comprehensive energy utilization rate for liquefaction and export

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