Spiral-vortex apparatus — effective equipment for the heat treatment of disperse materials

Abstract

In chemical and allied branches of industry, a large number of products and semi-products are manufactured in the disperse form (powder, grain, granule, etc.); in that case, they have, as a rule, an increased moisture content in the final stages of production. To ensure the required quality indicators of the products, their economic transport, and,shelf life, they are subjected to drying as the most accessible and widespread method of heat treatment.The following different convective drying apparatus, which operate under pneumatic transport, are widely used in industry: with stationary scavenged, pseudo-liquefied, and mechanically liquefied layers, and with mechanical agitation of the material.A highly developed surface is characteristic of disperse materials, and its maximum utilization during heat and mass exchanges serves as one of the basic means of improving the specific productivity of the apparatus, and lowering its effective volume, and, in turn, material consumption and maintenance outlays. Spiral-vortex apparatus, whose development, investigation, and industrial implementation have been studied for some time at the Moscow State for Chemical Machine Building fulfill these requirements to the greatest degree.Compactness, high intensity of the effective volume in terms of evaporated moisture, adaptability to manufacture, simplicity of operation, operational reliability, the possibility of drying materials with free and bound moisture, and the combination of several production processes in one apparatus are definite assets of the units under consideration. The existence of a spiral channel, and vortex and cyclone chambers in this type of drying apparatus ensures the most rational utilization of the potential of the drying unit, and eliminates large emissions of dust fractions to the atmosphere; in a number of cases, this does not require the additional installation of costly dust-controlling systems [1, 2].One of the first combined spiral-vortex driers is shown in Fig. 1 [3]. The combination of a spiral channel and vortex chamber makes it possible to retain the material in the apparatus for several tens of seconds; this ensures the removal of weakly bound moisture from the material. The pneumatic drier consists of rectangular spiral channel 7 and inlet pipe 1. The channel is formed by spiral strips 2, lateral wall 3, and removable cover 10. The channel is sealed using insert 11 and tie studs 12. The outlet from the spiral channel is the inlet to vortex chamber 4. Control valve 6, which is turned around axis 5, serves to regulate the time of residence of particles in the chamber. The dried material and expended drying agent are removed from the apparatus through scroll 8 and exhaust pipe 9.A spiral-vortex apparatus in which the solid phase is held in the vortex chamber for an extended time and the final product and expended drying agent are separated is shown in Fig. 2 [4]. The construction of the drier consists of flat bottom 10 and cover 1, spirals 9, which form rectangular channel 8, the latter being conn...