The 200,000-ton-per-year polypropylene plant at Dalian Petrochemical Company began operations just one month ago, marking a significant milestone for the company. The process has already demonstrated strong production advantages through its four key features. This facility is the second-largest of its kind within China Petroleum Corporation and utilizes second-generation polypropylene technology from Basell, a global leader in polypropylene production. The process involves a liquid-phase macro-loop reaction system, including catalyst preparation, prepolymerization, and polymerization, among other units. After establishing small, high-pressure, low-pressure, and large cycles, the catalyst initiates the polymerization reaction to produce polypropylene slurry. The slurry is then flash-vaporized, deactivated, dried, and finally extruded into pellets to form the final product.
The reactor unit includes one prepolymerization reactor and two series of loop reactors. The extrusion granulation section is equipped with two fully automated orbital portable packaging and palletizing lines. The catalyst system comprises titanium-based catalysts supported on magnesium chloride, triethylaluminum (TEAL), and an electron donor (DONOR). Prepolymerization occurs in a small loop reactor, while liquid-phase bulk polymerization takes place in two serial loop reactors. Each reactor is protected by three safety measures: emergency polymerization inhibition, bottom discharge of polymer, and connection of the upper bend to a safety valve for high-pressure discharge.
The four major features of the process provide distinct production advantages. With a fourth-generation catalyst system, the plant can produce bimodal polypropylene as well as materials with high rigidity, crystallinity, and clarity. The increased pressure levels during prepolymerization and polymerization allow for higher hydrogen content in the loop reactor, expanding the MFR range and improving product strength and performance. The dual-loop reactor design enables the production of both bimodal and narrow molecular weight distribution products. The use of loop reactors and liquid-phase bulk polymerization ensures better heat transfer and more uniform reactions. Additionally, the application of metallocene catalysts reduces the need for extensive retrofits in existing plants, shortens residence time, enhances reaction volume utilization, and improves degassing, steaming, and drying systems. These improvements increase efficiency and operational flexibility.
Dalian Petrochemical Company has selected T30S and T36F grades for their excellent production stability and marketability. It has also developed BOPP special materials tailored to the process’s capabilities. Currently, the company processes 20.5 million tons of crude oil annually, has a catalytic cracking capacity of 5.8 million tons per year, and produces nearly 280,000 tons of propylene yearly. The number of polypropylene products has expanded from 24 to 56, enabling the production of full-range and diverse products. These include packaging materials, automotive plastic components, and daily-use plastics, which are widely applied across various sectors of the national economy. This expansion has significantly boosted the company's propylene processing concentration and its competitiveness in the chemical market, elevating the integration of refinery gases into the chemical industry to a new level.
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