PRELIMINARY TECHNO-ECONOMIC FEASIBILITY STUDY FOR ESTABLISHING A 250MM LB/YR POLYSTYRENE PLANT

Polystyrene is a versatile plastic that is used in the manufacture of many consumer products 
such as appliances, electronics, car parts, foam , insulating and packaging materials .In a previous paper ,the 
viability of a local plant for producing styrene has been demonstrated suggesting that a techno-economic 
feasibility study for establishing a polystryrene plant is the next step. Here the results of this study are 
presented. 
After surveying the literature for relevant technologies, a recent US patent was selected as a manufacturing 
process. The technology is based on anionic polymerization chemistry and has the advantage of recycling 
part of the product as a heat sink for heat generated during reaction to soften products for further processing, 
suggesting a three step manufacturing process: feed preparation, adiabatic reaction and product finishing 
sections.
In feed preparation section commercial grade styrene is inhibited and continuously treated to remove 
impurities that can interfere with polymerization downstream. The inhibitor is removed in one of two beds 
of activated alumina, the other being regenerated. Temperature is carefully controlled to prevent thermal 
initiation.
The adiabatic reaction section is run batch wise. It consists of low temperature initiation reactor and two 
anionic polymerization reactors one operating while the other is being regenerated. Sufficient amount of 
solid product enters the reactor to control the temperature to the desired level. The finishing section is run 
continuously to accomplish termination, product finishing and purification. Material and energy balances in 
the original patent were reproduced and a preliminary economic feasibility was undertaken. The project is 
promising, with an internal rate of return in the range of 30 percent for a ten year operation and a payback 
period of 2.3 years.