Method for producing ethylene copolymerized polypropylene through propylene bulk gas phase combination technology

Abstract

The invention discloses a method for producing ethylene copolymerized polypropylene through a propylene bulk gas phase combination technology. Propylene polymerizes under the action of a catalyst containing a transition metal active site to generate polypropylene, the obtained polypropylene and ethylene polymerize in a gas phase reactor, an adhesion inhibitor is added in the polypropylene and ethylene polymerization process, and the adhesion inhibitor is a mixture of alcohol and an antistatic agent. The method has the advantages of no explosion danger, high polymerization production efficiency, low energy consumption, elimination of polymer adhesion, reduction of the adhesion of fine polymer powder to the inner wall of the reactor, stable device running, effective elimination of the scaling phenomenon of the inner wall of the reactor, solving of the problem of low polymerization efficiency caused by existence of a large amount of inert gas in the polymerization reactor, and solving of the problems of unsmooth conveying of a polymer in a discharging tube and reduction of the heat exchange efficiency of a heat exchanger.

Description

Technical field [0001] The invention relates to a method for producing ethylene copolymer polypropylene on a propylene bulk gas phase combined production process, and belongs to the field of olefin polymerization in the petrochemical industry. Background technique [0002] The existing polyolefin production process for industrial production is mainly liquid phase bulk and gas phase, with a single form of multi-tank combination, or two forms of multi-tank combination. Although there are various forms for the gas phase polymerizer, its characteristic is that it is mainly composed of two parts: a flow reaction part and a circulating heat exchange part. The gas phase polymerizer can avoid the formation of a small amount of low molecular weight copolymers dissolved in propylene during liquid phase bulk polymerization when producing propylene and α-olefin polymers. [0003] However, the existing gas-phase polymerizer must add the adhesion inhibitor LPN when producing the copolymer. LPN ...

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Problems solved by technology

[0003] But existing gas-phase polymerizer must add tack-resisting agent LPN when producing copolymer, and LPN is a kind of nitrogen containing oxygen, is used for preventing polymer particle surface from generating the undesirable sticky copolymer, but adds a large amount At the same time, LPN also brings a series of problems, such as, the oxygen and molecular weight regulator hydrogen in a.LPN have a very wide explosion limit, and the electrostatic effect on the surface of the polymer has the potential danger of hydrogen and oxygen explosion. For safety reasons, As a result, hydrogen cannot be added to the device when producing copolymers, which limits product performance optimization and production of different grades of products; b. The addition of a large amount of LPN and the accumulation of a large amount of inert gas reduce the partial pressure of effective monomers participating in the polymerization, resulting in polymerization production efficiency Decrease, roughly estimated, when nitrogen is balanced, the partial pressure is about 50%, and compared with no nitrogen, the polymerization production efficiency will drop by at least 50%; c. Excessive nitrogen increases the discharge frequency of the gas phase kettle, increases the amount of post-treatment separation, and improves production Cost, if it is directly emptied, the unit consumption of the product will increase significantly

[0004] At the same time, due to the unavoidable existence of polymerized fine powder in the reactor, under normal circumstances, there are still a very small amount of ultrafine particles that pass through the filter separation device of the fluidized bed and enter the circulation pipeline. These ultrafine powders still have a high Active, easy to attach to the inner wall and grow, so that a layer of polymer gradually grows on the inner wall, resulting in a sharp drop in heat exchange efficiency, increased energy consumption and blocked pipes. The cycle of normal and stable production is short, requiring manual and material resources to stop and clean

[0005] In addition, because polypropylene is a poor conductor of electricity, the continuous friction of the polymer flowing in the gas phase kettle will generate a lot of static electricity. Due to the electrostatic effect, some polymer fine powder or particles will adhere to the reactor wall, and those attached to the The fine powder on the wall of the feeding pipe and the inner wall of the heat exchanger will engulf part of the ethylene-propylene rubber formed after copolymerization, resulting in poor conveyance of the polymer in the feeding pipe and a decrease in the heat transfer efficiency of the heat exchanger. With the prolongation of production time during polypropylene copolymerization, it becomes more and more difficult to remove the heat, and blockage of the feeding pipeline occurs from time to time, which affects the stable operation of the device and also causes fluctuations in product quality

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