Reaction kettle and polyethylene production method

Abstract

The invention provides a reaction kettle and a method for producing polyethylene by using the reaction kettle. The reaction kettle comprises a kettle body and a stirring system arranged in the kettle body. The stirring system comprises a stirring shaft (8), the bottom of the stirring shaft (8) is connected with a stabilizer (11) used for stabilizing the stirring shaft, the top of the stirring shaft (8) is connected with a first rolling bearing (5), and the middle of the stirring shaft (8) is connected with one or more second rolling bearings (9). The stirring shaft adopts a fixing mode of supporting by an upper bearing and a middle bearing. As a conventional bottom bearing is abandoned and a top bearing is adopted, bearing lubrication is improved, bearing abrasion is reduced, meanwhile, a cantilever at the lower end of the stirring shaft is not restrained by high-temperature expansion, and thermal stress does not exist. Especially, the arrangement of the bottom stabilizer can effectively improve the radial swing of the stirring shaft, ensure that the stirring blades with large paddle diameter ratio do not collide with the wall, improve the flow condition of materials near the wall surface, avoid wall adhesion, reduce the wear of the bearing and realize long-period stable operation.

Description

technical field [0001] The invention specifically relates to a reaction kettle and a production method of polyethylene. Background technique [0002] Low-density polyethylene (LDPE) has a wide range of application requirements due to its light weight, good flexibility, low temperature resistance, and impact resistance. At present, the production process of LDPE can be divided into two types: tubular method and kettle method according to the different types of reactors. Among them, the main feature of the tubular reactor is that the stream flows in the shape of a plunger in the tube, there is no back-mixing phenomenon, the reaction temperature changes along the length of the reaction tube, and the molecular weight distribution of the obtained polyethylene is relatively wide; while the tank reactor usually Equipped with a mechanical stirring device, the materials can be fully mixed, the reaction temperature is relatively uniform, and it can be operated in different zones, so ...

AI Technical Summary

Problems solved by technology

Although the kettle-type polyethylene production has a history of several decades, and new structures have been proposed continuously, the high-quality mixing of the LDPE high-temperature and high-pressure reactor, the vibration of the high-speed slender stirring shaft, and the expansion of the high-temperature environment stirring system The life of the support bearing, the heat transfer of the autoclave body and other issues have not been well resolved or not well coordinated and matched, and urgently need to be improved

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