Process Design For An HDPE Pilot Plant

High density polyethylene (HDPE) capacity all the world locates in the third place of plastic production, and it is a kind of commonly used thermoplastic resin which has large capacity and widely use. Recently years, the production capacity of HDPE plant in domestic has increased rapidly, moreover there has been made considerable progress in the catalyst development, localization of technology and equipment and new product development. However, there is a big gap compared with same foreign production, the main features is in the special resin grades, low raw material production, product quality unstable, product specifications and varieties be not completed, the application limitations of new catalysts. In order to conform the development of high density polyethylene technology in the future, therefore it is necessary to build a set of pilot plant.In view of the current development situation of domestic polyethylene technology, a research institute intends to construct polyethylene in the pilot plant which mainly used for the application of new type of polyethylene catalyst evaluation and chlorinated polyethylene special materials, special materials for pipe, etc.This paper takes the pilot plant as the object to research its process design.Through the compare and analysis of the current domestic industrial device unit features, combining with the device experimental use and production characteristics, we determine the pilot plant using slurry process, and establish process and production unit which including catalyst preparation unit, polymerization reaction unit, powder processing unit and solvent recovery unit.Through experimental analysis of the three-phase flow mixing effect, we choose the best of the polymerization reactor agitator impeller combinations of five different impeller combinations stirrer. While building on the main production unit of dried powder flash tank unit model, completing its material and heat balance, on the basis of the design calculations and preliminary selection for the production of major equipment.Main tasks include: polymerization reactor design, powder drying flash tank design and selection, calculation and design condenser, pump selection and design.In this paper, from the perspective of ensuring safety, we analyze teh fire and explosion hazard of the process raw materials, solvents and products HDPE powder. Moreover, we take the Hazard and operability analysis (HAZOP) of polymerization vessel, discuss the deviation and reason of paradoxical reaction or out of control, while the design and develop the safety precautions. Safety relief device as an example to discuss the safety valve Discharge calculation conditions and calculation and selection.