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Abstract
DSM Engineering Materials, a large plastics company, has three new extrusion lines of different sizes at their Evansville facility. The extrusion lines utilize closed-loop, jet stream granulation cooling systems that cool the hot extruded plastic down to roughly 300 degrees Fahrenheit before entering the cutter head to be cut into uniform pellets. The cooling systems rely on plate and frame heat exchangers that each consist of a loop of process cooling water, and a loop of cooling tower water. The heat exchanger on the largest line (line 2) currently operates with suboptimal performance to the point of causing the line to be rate limited when running products with higher specific heat capacities. The heat exchangers used for the cooling system experience frequent fouling due to build up of various sediment and cannot be changed out easily due to poor connection designs.
This report presents a preliminary set of design changes to the cooling system that corrects the problems of suboptimal cooling, fouling, and rate limitation. The authors began by creating three different sets of design changes capable of increasing the cooling capacity of the system based on research of previously completed projects. After analysis, the final preliminary design was chosen. The final design chosen by the authors consists of increasing the number of plates on the existing plate and frame heat exchanger from 88 to 117. We concluded that adding an additional 29 plates and gaskets to the heat exchanger will resolve the issue of rate limitation, allowing the extruder to run at its maximum capability. Also, the project will have a return on investment of 8,600%.