Heat-and mass-exchange processes in a liquid-solid system depend heavily on the content of the solid phase and the gas-dynamic condition in the apparatus. The uniformity of the distribution of the solid phase throughout the volume of the apparatus exerts a significant influence on the effectiveness of mass exchange [1], while the flow regime of the heat-exchange surfaces of the solid phase and their contamination (incrustation, overgrowth of gaps, etc.) affect the efficiency of the heat exchange [2].At the present time, a type of circulation apparatus is widely used to carry out these processes. Suspension of the solid phase and circulation of the liquid in these apparatus are provided for by mechanical mixing units, for example, impeller-type mixers, and heat exchange is intensified by increasing the surface area of heat exchange by a block of concentrically arranged coils.In our opinion, use of vertical heat exchange elements in the form of twin tubes, which make it possible to realize a crossflow regime of the heat-exchange surface by the solid phase is most promising. We developed a design in the form of a standard cylindrical apparatus with a jacket, elliptical bottom, and fiat cover. The cover contains mounting seats for the drive of the mixer and for the vertical heat-exchange elements (blocks). Each of the six blocks consists of 12 heat-exchange elements (Field tubes). The heat-exchange elements assembled in a block can be connected in both series and parallel, and the blocks themselves in any order, which depends on the required motive force of the heat-transfer process, the consumption of the heattransfer medium, and the characteristics of the pumps used to move the heat-transfer medium. In the case of parallel tube connection, the construction of the blocks is collapsible; this makes it possible to clean the internal surface of the tubes periodically when necessary. The replacement of a block by a new one requires complete disassembly of the apparatus, and can be done without prolonged shutdown of the production process. With parallel pipe connection, each block consists of distribution and flow passages formed by circular channels between the external and internal tubes. In an apparatus with vertical elements, there is no funnel during the mixing and ingress of air. This increases the possibility of introducing mechanical energy that contributes to maintenance of a high rate of liquid circulation to the medium being mixed; this is particularly necessary for exothermal processes.The block system for the deployment of heat-exchange elements ensures the high maintainability of the apparatus; this is important when water with a high salt content is used as the heat-transfer medium.Experimental investigations were conducted to assess the effectiveness of heat transfer with allowance for nonuniformity of energy dissipation over the radius and height of the apparatus. Circulation of the continuous phase and uniform distribution of the solid phase throughout the volume were accomplished with the use of a mech...
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