For the production of regular and flame-retardant expandable polystyrene, INEOS offers the “one-step” suspension process. Products and economics: This state-of-the-art technology offers a wide range of products with an attractive capital investment and operational costs. Computer control and monitoring ensure consistent products with capacity up to 100,000 tpy per line.
Depending on the formulation, styrene, blowing agent, water, initiators, suspending agents and other additives are injected into the reactor (1). The reactor contents are then subjected to a time-temperature profile under agitation. The combination of suspending agent and agitation disperse the monomer to form beads. Polymerization is then continued to essentially 100% conversion. This unit operation is fully DCS controlled through an automated sequence. After cooling, the polystyrene beads and water are discharged to a slurry tank (2).
The downstream slurry tank process becomes fully continuous. The bead/water slurry is centrifuged (3) so that most of the “suspension water” is removed. The beads are conveyed to a pneumatic-type flash dryer (4) where surface moisture is removed.
The dry beads are then screened (5) yielding two targeted product cuts out of four possible options. Such segregation is achievable thanks to the mineral suspension, which increases the yield for a targeted cut. With organic suspensions, the four product cuts are produced at the same time. Fig. 2 shows the effects of mineral vs. organic suspension in terms of product size distribution. Narrower distributions allow targeting more specifically product cut in line with market needs. Typically, the fine to medium cuts target the packaging market, whereas the medium to big cuts target the insulation market.
Process advantages:
• Regular and flame-retardant grades available
• Narrow-bead size distribution thanks to the mineral suspension system
• High reactor productivity/high capacity design (up to 100,000 metric tpy on a single line)
• Proven and easy to operate technology
• Optional volatile organic compound (VOC) recovery system
• The process includes batch reactions automatically controlled followed by a fully continuous downstream section
• Continuous low residence time coating process.
Market advantages:
• Outstanding raw material and utility yields
• Consistent high-quality products widely accepted in the marketplace
• Best packaging grade offer of the market and universal flameretardant product range
• Clean process
• High quality yields (above 99% prime)
• High selectivity allowing to fit market demand
• High reliability
• Ongoing development of new and improved, market-specific formulations
• Excellent technical support from INEOS.
Licensor: INEOS Technologies
