Method for completely reclaiming tail gas of polyethylene device

Abstract

The invention relates to a method for completely reclaiming tail gas of a polyethylene device, which is a method used for reclaiming and recycling a comonomer, an induction condensing agent and ethene in the tail gas after the polyethylene device passes through a high-low pressure cooling and condensing reclaiming system and completely classifying and reclaiming hydrocarbon components with low pressure and high nitrogen content in the tail gas. The tail gas of the polyethylene device first enters a membrane separation reclaiming unit to reclaim the comonomer, the induction condensing agent and the ethene in the tail gas; the tail gas is cycled to an inlet of a compressor, and then returns to a reaction system for reclamation. The waste gas after membrane separation and reclaiming enters a buffer tank; the waste gas discharged by the buffer tank to a flare is introduced to a pressure swing adsorption system for reclamation; the hydrocarbon components are separated from the waste gas, and enter a fuel gas system for comprehensive utilization; and simultaneously concentrated nitrogen is used for the device to purge gas to realize complete reclaiming of the tail gas and zero discharge of flare gas. The method has short production process technical flow, simple operation and easy control, embodies the comprehensive utilization of resources and is favorable for environmental protection.

Description

Technical field [0001] The present invention relates to a method for recycling tail gas of a polyethylene device. More specifically, the present invention relates to a method for completely sorting and recovering tail gas from a polyethylene device through a high and low pressure cooling condensation recovery system. Exhaust gas includes process exhaust gas and flare gas in normal production process, which are hydrocarbon components with high nitrogen content. Background technique [0002] Polyethylene (PE) equipment occupies a very important position in the polymerization process. In the PE production process, many unreacted monomers ethylene, hydrogen, comonomers (such as butene-1, hexene, octene, etc.) and inducing condensing agents (such as isopropyl) are taken out while the inert gas is discharged from the reactor. Pentane, hexane) and so on. At the same time, the polyethylene powder also contains a lot of unreacted monomer ethylene, comonomers (such as butene-1, hexene, oct...

AI Technical Summary

Problems solved by technology

[0007] CN101265153A discloses the method utilizing membrane separation and recovery process to reclaim organic hydrocarbons and nitrogen in polyethylene (PE) plant tail gas, but this process is only effective for the recovery of normal hexane and nitrogen, and still has a large amount of carbon-containing two or more such as ethylene, ethyl ether, etc. The tail gas of alkanes and other hydrocarbons needs to be flared and burned, which is far from meeting the requirements of zero emissions

[0008] CN1800308A, CN1789381A, CN1861245A etc. disclose the method for separating and recovering ethylene and ethane from the mixed gas by using the pressure swing adsorption method. However, these methods are only for the recovery of ethylene, ethane, etc. in the catalytic dry gas of the refining system, which is convenient for the use of downstream ethylene units

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