Enhanced Process Sustainability in Polymerization and Devolatilization Technologies
May 10-15, 2015
More stringent regulations have made of process intensification and sustainability critical topics when developing new processes or revamping existing assets. This has translated into efforts to lower VOC emissions, optimize energy consumption, increase capacity and improve efficiency of the polymerization process and downstream equipment. Since several decades Sulzer is active in the development and supply of process solutions for reaction, devolatilization and upgrading of polymers.  The technology is successfully implemented in industrial polymerization and devolatilization plants to enhance the process sustainability. In the first part of this work, the use of static mixers and Sulzer Mixer Reactor (SMR) in different polymerization processes is presented. The equipment is characterized by high mixing and heat transfer efficiency, which avoid concentration and temperature gradients. These aspects are fundamental for the production of thermo-sensitive polymers and for highly exothermic processes. A key aspect of this equipment is that it has a heat transfer capacity which is almost independent upon the reactor volume which represents an advantage for process optimization since the process can be reliably scaled down to versatile pilot scale reactors where process parameters and design are optimized. Different reactor configurations are compared in terms of productivity, heat duty and process stability and control. The second part of the work is focused on the devolatilization technology. Devolatilization of monomers, solvents or impurities is a key step in most polymerization processes because it determines polymer quality, applicability and value. Depending on the polymerization process, from a process cost point of view, degassing can account for up to 80% of the energy consumption.  In general, the devolatilization processes are classified as static or dynamic processes and are suitable for a wide range of viscosities. For low volatile content, due to the high viscosity of polymer melts, the devolatilization is characterized by diffusion limitation and thus requires an efficient process that enhances the removal performance by increasing the polymer residence time and the transport specific area and by decreasing the partial pressure of the volatile components in the gas phase with the use a suitable stripping agent. A patented static devolatilization technology suitable for high viscous and thermal sensitive material is presented for two main applications named first stage and final stage processes. The different aspects of the polymerization and devolatilization technologies are presented through case studies. Each case is analyzed on the base of process performance improvements, polymer quality and/or process economics. The experimental work carried out on pilot scale and in the laboratory is presented and the process performances are studied as a function of selected process parameters.
 http://www.sulzer.com/it/Products-and-Services/Process-Technology/Polymer-Production-Technology  Reference Document on Best Available Techniques in the Production of Polymers, European Commission, August 2007