Abstract: A process for filtering polymer melt which minimizes the generation of dead zones in the filter and provides uniform residence time and accurate temperature control. The process is carried out in an apparatus comprising a plurality of heat exchanger pipes, each enclosing a filter cartridge surrounded by an annular space which terminates at its upper end in a plurality of narrow channels. The molten polymer is charged into the annular space and divided into primary and secondary streams. The primary stream flows through the filter cartridge and the secondary stream, which constitutes 0.03 to 3.0 weight percent of the weight of the combined streams, flows through the narrow channels, whereupon the streams are combined and discharged from the apparatus. The discharge temperature of the polymer is maintained within .+-.1.degree. C. of the charging temperature and the heat exchanger fluid enters the apparatus at a temperature within 1.degree. and 5.degree.C. of the temperature of the melt.

Abstract: A polymer melt filtration apparatus comprising a closed upright cylindrical vessel divided by two horizontal pipe plates into a small lower product distribution chamber with a product inlet at the bottom, a small upper product collecting chamber with a product outlet at the top, and a large middle chamber connected to a heat carrier fluid circuit. A plurality of closely spaced heat exchanger pipes are mounted in the middle chamber between the pipe plates and surrounded by heat carrier fluid, each pipe enclosing a filter cartridge detachably connected at its upper end to said pipe and radially spaced therefrom to form an annular space around each cartridge. A series of narrow channels are provided between the upper end of the annular space and the upper collecting chamber to impede the generation of dead zones inside the annular space and the collecting chamber. The main polymer melt stream flows inside the pipes through the filter cartridges.