Post-processing method for polypropylene powder

Abstract

The invention provides a post-processing method for polypropylene powder, which belongs to the petroleum chemical field. In the polypropylene post-processing method of the prior art, the method comprises the following steps: polypropylene powder which departs from a polymerization system and is carried out preliminary gas / solid separation enters into a drier, indirectly heated through steam and nitrogen is introduced, hydrocarbons can be removed in powder and then enters in a steamer, nitrogen and water vapor are introduced for inactivation of a catalyst; or the polypropylene powder which departs from a polymerization system and is carried out preliminary gas / solid separation enters into a degassing chamber, water vapor-containing nitrogen is introduced in the degassing chamber; the present invention modifies the prior art. The post-processing method of the invention comprises the following steps: introducing water vapor, modifying the drier to a steam drier used for recovering hydrocarbons and inactivating the catalyst, introducing a hydrocarbons-removed polymer in the steam drier (or a degassing chamber), adding nitrogen without water vapor in the steam drier, modifying the steam drier to a moisture eliminator used for removing water vapor in powder. The method of the invention is capable of thoroughly recovering hydrocarbons which depart from the polymerization system by an economic method, reducing the unit consumption and energy consumption, and thoroughly solving the problem on environmental protection.

Description

technical field [0001] The invention belongs to the field of petrochemical industry. Background technique [0002] The content of the present invention relates to a method for deactivating, removing and economically recovering the hydrocarbons carried in the powder in the process of producing polypropylene, the residual catalyst in the polypropylene powder after leaving the polymerization reactor. [0003] As we all know, after the synthesis of polypropylene, the polypropylene powder leaving the polymerization system carries a certain amount of hydrocarbons, some of which are dissolved in the polymer and some are free. The purpose of post-treatment of polypropylene powder is to remove these The carried hydrocarbons are removed, and at the same time, the residual catalyst (including catalyst and aluminum alkyl) in the powder is deactivated. The above process of removing hydrocarbons is generally called degassing or devolatilization (or drying), and the process of decomposing...

AI Technical Summary

Problems solved by technology

But still can not completely solve the problem of reducing unit consumption

Owing to not feeding nitrogen in the drier, the hydrocarbons carried when the polypropylene powder enters the steamer by the drier are compared with Japanese Patent Laid-Open No. 58-157807, No. 56-139520 (Mitsui Oil & Chemical) when passing nitrogen in the drier. When the dryer enters the steamer, it carries more hydrocarbons, which brings environmental problems when the exhaust gas of the steamer is discharged.

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