Nurzafirah Mohd Supion, Anis Mansor, Arina Sauki, Siti Nor Azreen Ahmad Termizi, Iylia Idris, Ayub Md Som, Ahmad Ilyas Rushdan, Fakhrony Sholahuddin Rohman, Ashraf Azmi
The polymerization process of low-density polyethylene (LDPE) in a tubular reactor suffers from low ethylene conversion and high production cost since the reaction has high exothermicity and the expensive heating and cooling requirements. Both issues are considered during the optimization of LDPE production to achieve maximum profit without violating thermal safety regulations. However, optimizing for monomer conversion (XM), typically correlated with profitability, makes this operation complex. Consequently, an optimization study was conducted to maximize the profit of LDPE production while adhering to safety and product quality constraints. The kinetic rate parameters were chosen before the optimization study began. The study focused on the first zone of the LDPE tubular reactor with an involvement of several mass and energy balance. Based on sensitivity studies, the optimized input parameters were chosen, including flowrate of monomer (FM), flowrate of solvent (FS), flowrate of initiator (FI), reactor inlet temperature (Tin), inlet pressure (Pin), and reactor jacket temperature (TJ). These parameters significantly influenced the performance and quality of LDPE, as measured by the melt-flow index (MFI). In various constraint case studies, reaction temperature constraint optimization achieved a higher XM than the base case and other constrained scenarios which aligns with the thermal safety regulations. Additionally, six control variables were considered. The constraints of maximum temperature (Tmax) and melt-flow index (MFI) were successfully satisfied in all cases. The highest monomer conversion and profit were 13.55% and RM98.51 million/year respectively. Overall, the optimization method successfully resolved the complex relationship between process parameters for the LDPE tubular reactor. The study demonstrates a trade-off between objective functions and constraints without compromising any crucial elements. © 2025 Author(s).
School of Chemical Engineering, College of Engineering, Universiti Teknologi MARA, Shah Alam Selangor, 40450, Malaysia; Faculty of Chemical Engineering and Technology, Universiti Malaysia Perlis, Kompleks Pusat Pengajian Jejawi 3, Kawasan Perindustrian Jejawi, Arau, Perlis, 02600, Malaysia; School of Chemical and Energy Engineering, Faculty of Engineering, Universiti Teknologi Malaysia (UTM), Johor Bahru, Johor, 81310, Malaysia; Department of Chemical Engineering, Universitas Brawijaya, Jalan Mayjen Haryono 167, Malang, 65145, Indonesia; Process Systems Engineering Centre (PROSPECT), Research Institute for Sustainable Environment, Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia, UTM Johor Bahru, Johor, 81310, Malaysia
