Industrial Application Of Gas - Phase Polyethylene Process Slurry Catalyst

Gas phase method of linear low density polyethylene(LLDPE) process is widely used because of its simplisity, technical and economic benefits, easy and flexible operation, high safety and so on. After technical reconstruction for 3 times, the LLDPE device in a Certain Petrochemical Company using condensation technology operation reached production capacity from the original 10 million tons/year to 27.4 million tons/year. With the great increase of production capacity, catalyst residence time was reduced accordingly, leading to abrupt increase of catalyst ash content in polyethylene products. Meanwhile, the qualityies of the optical property, mechanical strength, and surface appearance declined remarkably. In recent years, most domestic LLDPE devices using powder similar slurry catalysts have been improved. New device directly used catalyst slurry feeding technique. A certain Petrochemical Company is one of petrochemical industries still using M-1 type solid dry powder catalyst.Based on the gas-phase condensation LLDPE techanology with fluidized bed catalyst, this thesis selected one petrochemical company for studing the improvement feasibility of the catalyst slurry technology by comparing with the solid powder catalyst. The main researches are listed as follows.1. Through laboratory experiments, the model of K-1 slurry catalyst and imported J catalyst in polymerization and polymerization of polyethylene resin performance comparison of the mechanical properties and so on domestic K-1 catalyst can completely replace the imported similar catalysts.2. By usingK-1slurry catalyst in Unipol gas phase polyethylene plant, we comparied the activity, process conditions, powder particle size, product quality with those by using M-1 type solid dry powder catalyst. We confirmed the feasibility for additionally providing a catalyst slurry feeding system and introducing a highly active slurry catalyst.3. After implementation of the technological transformation of slurry catalyst, we studed and mastered the operation of slurry catalyst feeding system, the switching operation between slurry catalyst and the powder catalyst, the smooth control of the reaction system under the conditions using slurry catalyst, and the adjustment of the slurry catalyst activity. Based on those results, we could maintain the smooth operation of the device in a long period after the implementation of the transformation of slurry catalyst.4. Finally, we evaluated the polyethylene produced under the conditions using slurry catalyst. We compared the mechanical strength, optical property, terminal product quality and other changes by using slurry catalyst and the powder catalyst.