A polyethylene device reactor seed bed dehydration replacement device and method

Abstract

The invention relates to a device and a method for dehydration replacement of a reactor seed bed of a polyethylene device. The device comprises a seed bed treatment tank with a jacket temperature-control device, a nitrogen inlet pipe and its valve, a root valve, a seed bed feeding inlet pipe and its valve, a stirring device, an escape pipe and its valve, and a safety accessory. The method comprises that when a seed bed is transferred into the seed bed treatment tank by air or nitrogen, a temperature of the seed bed treatment tank is controlled in a range of 80-90 DEG C, refined nitrogen is fed into the seed bed treatment tank to improve pressure in the seed bed treatment tank to a certain pressure, the valve of the escape pipe is opened so that pressure replacement is realized, and the above processes are repeated more than 10 times until the content of impurities such water and oxygen of the seed bed is less than 10*10<-6>ppm. According to the method, fast removal of impurities of the seed bed is realized only by arrangement of the dehydration replacement device at a seed bed inlet of the original reactor without operation of a recycle gas compressor and a purge gas compressor. The method can prolong a device service life, saves raw materials and power, is safe and environmentally friendly and is simple and feasible.

Description

Technical field: [0001] The invention relates to a dehydration replacement device and method for a reactor seed bed of a full-density polyethylene device by a gas phase method, which belongs to the process control of ethylene polymerization in a gaseous state. Background technique: [0002] The Unipol gas-phase full-density polyethylene process occupies a dominant position in the world's gas-phase polyethylene process. At present, 9 sets of Unipol polyethylene plants have been put into operation in my country, and another 11 sets are under construction, which is the number of sets in various polyethylene processes in my country. The one with the most and the largest production capacity. [0003] Before starting up the Unipol gas-phase full-density polyethylene plant, it is necessary to pre-load a certain height of polyethylene powder into the reactor, which is called a seed bed. Since the transport of the seed bed to the reactor is accomplished by an air blower, the seed bed...

AI Technical Summary

Problems solved by technology

This method is simple and feasible, but when using this method to replace the seed bed in actual operation, it still needs to waste a lot of nitrogen to replace the circulation gas heat exchanger and circulation pipeline

Images