This Vertical Reactor is designed to maximize heat transfer by making use of an exterior jacket shell. The horizontal tubes are fed continuously as a parallel operation. Free falling streams of heated styrene pass through a mixer with multiple single cross blades between the individual layers of horizontal tubes. The mixer is driven by co-ordinated hydraulic drives on each end of the shaft for quiet operation. All-Weld has supplied polystyrene reactors to customers in the United States and Indonesia.