Crude oil volatile gas graded liquefaction system and working method thereof

Abstract

A crude oil volatile gas graded liquefaction system comprises a crude oil volatile gas graded liquefaction circulation system, a pure refrigerant refrigeration circulation system and a mixed refrigerant refrigeration circulation system, and in the crude oil volatile gas graded liquefaction circulation system, crude oil volatile gas sequentially passes through a first heat exchanger, a second heatexchanger and a third heat exchanger; the graded liquefaction is achieved through a fourth heat exchanger and a fifth heat exchanger, and the crude oil volatile gas is reheated by the fifth heat exchanger from a fourth gas-liquid separator, then is compressed and heated through a second compressor, and enters a third compressor through a first cooler for compression and pressurization; and residual gaseous crude oil volatile gas separated by a fifth gas-liquid separator through the fifth heat exchanger enters an expansion machine for expansion refrigeration. According to the graded liquefaction system, protective gas nitrogen in the crude oil volatile gas is used as a refrigerant for nitrogen expansion refrigeration, and power consumption of the compressor is compensated through recyclingof work done by an expansion machine; the problem of high energy consumption of external low-temperature equipment is solved, and the refrigerating capacity of the system is flexibly adjusted throughregulation of nitrogen flow; and the system has high adjusting ability of cooling capacity.

Description

technical field [0001] The invention relates to the graded liquefaction recovery of crude oil volatile gas produced during the storage and transportation of crude oil, in particular to a crude oil volatile gas graded liquefaction system and a working method thereof. Background technique [0002] Crude oil is a mixture of various liquid hydrocarbons such as alkanes, naphthenes and olefins, which is characterized by strong volatility. At the same time, as an indispensable energy source, crude oil accounts for a large proportion of the primary energy consumption structure. All countries need to import oil from the Middle East to meet their own energy supply needs, and crude oil will produce a large amount of volatile gas during storage and transportation. Based on the requirements of protecting the environment and saving energy, direct discharge of volatile gas from crude oil should be avoided to cause Environmental pollution, and this does not meet the economic requirements, s...

AI Technical Summary

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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