A crude oil volatile gas graded liquefaction system and its working method

Abstract

A crude oil volatile gas classification liquefaction system, including a crude oil volatile gas classification liquefaction circulation system, a pure refrigerant refrigeration circulation system and a mixed refrigerant refrigeration circulation system, in the crude oil volatile gas classification liquefaction circulation system, the crude oil volatile gas passes through the first heat exchange in sequence The second heat exchanger, the third heat exchanger, the fourth heat exchanger and the fifth heat exchanger realize staged liquefaction, the volatile gas of crude oil is rewarmed from the fourth gas-liquid separator through the fifth heat exchanger, and then passed through The second compressor compresses and heats up, and then enters the third compressor through the first cooler for compression and boosting, and the remaining gaseous crude oil volatile gas is separated through the fifth heat exchanger and the fifth gas-liquid separator and enters the expander for expansion and refrigeration. The invention uses the protective gas nitrogen in the volatile gas of crude oil as a refrigerant to carry out nitrogen expansion refrigeration, compensates the power consumption of the compressor by recovering the work done by the expander, reduces the problem of high energy consumption of peripheral low-temperature equipment, and adjusts the flow rate of nitrogen to achieve flexible Adjust the cooling capacity of the system and have good cooling capacity adjustment capabilities.

Description

technical field [0001] The invention relates to the classification and liquefaction recovery of crude oil volatile gas generated during the storage and transportation of crude oil, in particular to a crude oil volatile gas classification liquefaction system and a working method thereof. Background technique [0002] Crude oil is a mixture of various liquid hydrocarbons such as alkanes, cyclic hydrocarbons and alkenes. It is characterized by strong volatility. At the same time, crude oil, as an indispensable energy source, accounts for a large proportion of the primary energy consumption structure, most of which are in Europe, America and Asia. Countries need to import oil from the Middle East to meet their own energy supply needs, and crude oil will generate a large amount of crude oil volatile gas during storage and transportation. Based on the requirements of protecting the environment and saving energy, the direct emission of crude oil volatile gas should be avoided. Envi...

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Problems solved by technology

The traditional crude oil volatile gas liquefaction recovery method usually adopts the condensation method, and through the external refrigeration equipment, the condensation temperature is reduced to -170°C to ensure that the crude oil volatile gas is completely liquefied and recovered, and then meets the national emission standards, but such a low The refrigeration temperature means a lower energy efficiency ratio, and there are many ways to obtain a low temperature of -170°C through system design or peripheral refrigeration equipment. Therefore, it is necessary to design and select a reasonable refrigeration method and use a reasonable system design to reduce the entire liquefaction process. The required energy consumption becomes very necessary

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