MODELING THE OPERATION OF A COOLING SYSTEM FOR RETURN ETHYLENE IN THE PRODUCTION OF HIGH-PRESSURE POLYETHYLENE

The authors have presented a mathematical description of the process of cooling of ethylene in countercurrent heat exchangers of the "double-pipe" type, where the ethylene gas is flowing in the inner tube, and water is moving countercurrently in the intertubular space. Such a system belongs to the basic cycle of polymerization of ethylene by the high-pressure method. Basic properties of heat-exchange apparatuses of a cooling system and its parameters have been described. The interrelation between such physical quantities as pressure, temperature, flow rates of coolants, and heat-transfer surfaces of circulating water and return ethylene has been determined. The proposed model takes account of the "sticking" of a liquid polymer onto interior tube walls.