Energy-saving process method for recovering butane in mixed C4

Abstract

The invention relates to an energy-saving process method for recovering butane in mixed C4. Raw materials are firstly subjected to pretreatment through an alkane and alkene crude separation tower T101; a heat exchanger E101 is used for performing heat exchange on tower kettle materials and high-temperature extracting agents extracted from the tower bottom of an extracting agent recovery tower II T105 at the T101 bottom. An extraction rectifying tower T102 uses an intermediate reboiler E201 for heat exchange with high-temperature extracting agents extracted from the tower bottom of the extracting agent recovery tower II T105. An extraction rectifying upper tower T103 is added; a tower kettle reboiler E301 of the extraction rectifying upper tower T103 is heated through tower top gas phase extraction of an extraction rectifying tower II. Through heat integration, the separation of alkene and alkane can be realized; different grades of heat in the butane recovery processes is fully utilized; the energy consumption required in the rectification process is reduced. The energy is saved by 45 percent or higher; the circulating water consumption is reduced by 28 percent or higher. The problem of butene and butane separation is effectively solved; the iso-butane purity is greater than or equal to 99.8 percent; the yield is greater than or equal to 95 percent.

Description

technical field [0001] The invention relates to a method for refining butane, in particular to an energy-saving process for recovering and mixing butane in C4. Background technique [0002] With the increase of my country's ethylene production and crude oil processing capacity, steam cracking units and catalytic cracking units will produce a large amount of C4, while the high alkane content in mixed C4 restricts the effective utilization of olefins. The main components of mixed C4 are butene and butane, which have close boiling points and are difficult to separate by ordinary rectification. [0003] Patent CN103508830A proposes a method for separating alkanes and olefins in the C4 fraction after ether. In this method, the C4 fraction after ether is reacted with acetic acid to produce sec-butyl acetate, and then sec-butyl acetate is cracked to obtain acetic acid and n-butene. However, there is not only n-butene in C4 after ether, but other olefins can also participate in the...

AI Technical Summary

Problems solved by technology

Using extractive distillation to separate butane and butene is an effective process method. However, the extractive distillation process requires an extraction ratio greater than or equal to 15 to achieve a higher separation purpose. Therefore, the number of theoretical plates is relatively high. High, which not only has higher requirements for equipment cost, but also consumes a lot of energy

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