Mixer-Heat Exchangers

In many conventional types of heat exchangers, the cooling or heating of laminar flow, viscous media often gives rise to problems due to the formation of boundary layers which can sharply inhibit thermal exchange. For applications of this kind, there has been a notable increase in the use of static mixer-heat exchangers which provide continuous radial mixing, and thus successfully prevent, or at least strongly reduce the build-up of boundary layers. Another feature is the narrow residence time spectrum which is a decisive factor in the processing of temperature-sensitive viscous media, e.g. polymers.

The company's mixer-heat exchangers with SMXL or KHT mixing elements are available in either mono-tube or multi-tube versions. These static mixer internals increase the heat transfer coefficient by a factor of 6 to 8 compared to empty pipe configurations. They are used not only for rapid heating up application, for example, the heating of polymer solutions during manufacture of PS, LLDPE and similar types of plastic materials prior to degassing, but also for the efficient cooling of viscous media.

The mixer-reactor SMR is a special type of mixer-heat exchanger. Its mixing elements are formed of a series of hollow tubes through which the heat transfer medium flows. The arrangement of the tubes in the apparatus is such that they induce strong radial mixing. The SMR is used mainly either as a polymerization reactor or a cooler. In it, the fluid being treated under plug flow conditions (narrow residence time spectrum) is continuously subjected to mixing across the entire cross-section of the flow (compensation of concentration and temperature), and at the same time heat is either being introduced or removed. Besides purely cooling tasks, the SMR reactor is employed everywhere where a reaction (with single or two-phase flow) has to be carried out under defined time/temperature conditions.

A special design program for these static mixer-heat exchangers allows the company to offer its customers the optimal unit for each specific application. In particular, it can ensure that in cooling processes involving the use of multi-tube mixer-heat exchangers , maldistribution between the individual tubes is reliably prevented, and that consequently there will be no impairment of heat exchanger efficiency. SMR mixer reactors are supplied to withstand operating pressures and temperatures of up to and over 300 bar/°C, e.g. for the cooling of polyester melts in direct spinning plants. SMR units are currently available in nominal diameters of DN 100 to DN 1500.

Koch-Glitsch Mixing & Reaction Technology, 4111 East 37th St. North, Wichita, KS 67220. Tel: 316-828-4145; Fax: 316-828-4444.