Method for recovering exhaust gas according to polyolefin gas phase method

A recovery method and technology for polyolefins, applied in separation methods, chemical instruments and methods, nitrogen purification/separation, etc., can solve the problems of low recovery efficiency, unfriendly environment, large consumption of raw materials, etc., to reduce material consumption and flare emissions The effect of high volume, high recovery rate and low energy consumption

Active Publication Date: 2015-09-23
CHINA HUANQIU CONTRACTING & ENG CO LTD
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  • Abstract
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  • Claims
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Problems solved by technology

[0007] To sum up, the existing tail gas recovery methods have disadvantages such as low recovery efficiency, high energy consumption, high raw material consumption, and unfriendly environ

Method used

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  • Method for recovering exhaust gas according to polyolefin gas phase method
  • Method for recovering exhaust gas according to polyolefin gas phase method

Examples

Experimental program
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Effect test

Embodiment 1

[0049] Such as figure 1 As shown, the polypropylene homopolymer is produced by the gas phase fluidized bed process, the reaction temperature is 66° C., and the reaction pressure is 3.38 MPag. Driven by the conveying carrier gas, the solid polypropylene discharged from the reactor enters the vertical product receiver through the discharge system, and the residual hydrocarbons in the polypropylene are removed by nitrogen purge, and the exhaust gas 1 is firstly recovered after being filtered The air cooler B1 is cooled to 42°C, and then enters the compression and condensation process. The outlet pressure of the first compressor B2 is 0.28MPag, and the outlet temperature of the first cooler B3 is 42°C; the outlet pressure of the second compressor B4 is 1.14MPag, and the outlet pressure of the second compressor B4 is 1.14MPag. The outlet temperature of the second cooler B5 is 42°C; the outlet pressure of the third compressor B6 is 4.10MPag, and the outlet temperature of the third c...

Embodiment 2

[0055] Such as figure 2 As shown, the ethylene-butene copolymerized linear low density polyethylene LLDPE is produced by the gas phase fluidized bed process, the reaction temperature is 88°C, the reaction pressure is 2.1MPag, and the condensation operation is adopted, and the condensing agent is isopentane. The solid polyethylene discharged from the reactor is driven by the carrier gas, and enters the degassing chamber through the discharge system, and the residual unreacted monomer and solvent in the polyethylene are removed by nitrogen purge, and the exhaust gas 1 is filtered and firstly After being cooled to 42°C by the recovery gas cooler B1, it enters the multi-stage compression and condensation process. The outlet pressure of the compressor is 2.0MPag, and the outlet temperature of the cooler is 20°C. The compressed, condensed and separated uncondensed gas 2 enters the heat exchanger B8 to be cryogenically cooled and then enters the gas-liquid separator B9 for separatio...

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Abstract

The invention relates to a method for recovering exhaust gas according to the polyolefin gas phase method. The method for recovering the exhaust gas comprises the following steps: 1) compression, condensation and separation steps are carried out; 2) after the compression, condensation and separation steps, gas enters a heat exchanger to be subjected to cryogenic separation; 3) compressed and condensed liquid and liquid subjected to cryogenic separation are subjected to gas-liquid separation through a separation tank, and after the flash evaporation, light component gas flows to a compressor to be recycled; 4) after cryogenic separation, part of uncondensed gas enters a membrane separation device to enable hydrocarbons to be further recovered; 5) after membrane separation, hydrocarbon-rich phase gas returns back to the compressor to be recycled, hydrogen-deficient phase gas flows to an unpowered expansion refrigeration device to enable hydrocarbons to be recovered, and obtained high-purity nitrogen is used as supplementation gas for sweeping gas of a product receiving bin or a degassing bin. According to the method for recovering the exhaust gas, unreacted monomers can be effectively recovered, the gas emission can be reduced, the total utilization of the monomers can be increased, the gas consumption amount of the sweeping gas can be reduced, the cost can be reduced, the power of the compressor can be reduced, and the energy consumption of the heat exchanger can be reduced.

Description

technical field [0001] The invention relates to a method for recovering tail gas, in particular to a method for recovering tail gas in a process for synthesizing polyolefins by a gas phase method. Background technique [0002] In recent years, with the rapid development of the world's petrochemical industry, coal chemical industry and propane dehydrogenation technologies, the quantity and production capacity of polyolefins have increased rapidly. In 2007, the world's polypropylene production capacity was 48.26 million tons per year; in 2012, the world's polypropylene The production capacity reaches 64.3 million tons / year. In China, due to the large gap between the supply and demand of polyolefins in China, most of the newly built domestic large-scale oil refining and ethylene projects are equipped with polyolefin devices downstream; in addition, with the construction boom of coal chemical projects in my country, the production capacity of coal head polyolefin projects will g...

Claims

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Application Information

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IPC IPC(8): B01D53/00B01D53/22C01B21/04F25J3/00C08F10/00C08F2/34C08F6/00
Inventor 刘灿刚武大庆陈美娟王一叶宁崔玉航江沛刘志芳陈巧力
Owner CHINA HUANQIU CONTRACTING & ENG CO LTD
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