The production processes of high grade II polyethylene (HDPE) outer skins of Longchangjie Machinery Co., Ltd. mainly include the following methods: gas-phase method, slurry method and solution method.
The following introduces several methods in detail:
1. Gas-phase method: In a gas-phase reactor, ethylene monomers directly polymerize to form polyethylene under the action of a catalyst. Representative processes include the Unipol process.
2. Slurry method: Ethylene monomer dissolves in a diluent to form a slurry, which polymerizes under the action of a catalyst. Typical processes include the Hostalen process.
3. Solution method: Ethylene is dissolved in a solvent for polymerization, and then the solvent is separated. Although the solution method is more commonly used in the production of linear low-density polyethylene (LLDPE), it was also used in the production of HDPE in the early days.
The characteristics and application scopes of different production processes:
· Gas-phase method: Represented by Univation's UnipolPE process, it uses a single fluidized bed reactor, featuring a simple and efficient process with relatively low investment costs. It is suitable for the production of high, medium and low density products.
· Slurry method: Represented by Basell's Hostalen technology and Chevron Phillips' MarTech technology, it adopts stirred tanks or ring tube reactors and is suitable for the production of multi-peak HDPE products.
· Solution method: Although it is mainly used in the production of LLDPE, it was also used in the production of HDPE in the early days.
The specific steps of the production process:
Take the slurry method as an example. The production process includes units such as raw material refining, catalyst preparation, polymerization reaction, solid concentration and high and low pressure flash evaporation, solvent recovery, air conveying, granulation, and public utilities. The polymerization reaction takes place in the diluent. After the reaction, the solid particles and the diluent are separated through a flash evaporation system, and finally granulation and solvent recovery are carried out.
