Thermal Design for Solids Processing

Design Methods for Calciners In indirect-heated calciners, heat transfer is primarily by radiation from the cyhnder wall to the solids bed. The thermal efficiency ranges from 30 to 65 percent. By utilization of the furnace exhaust gases for preheated combustion air, steam produc tion, or heat for other process steps, the thermal efficiency can be increased considerably. The limiting factors in heat transmission he in the conductivity and radiation constants of the shell metal and solids bed. If the characteristics of these are known, equipment may be accurately sized by employing the Stefan-Boltzmann radiation equation. Apparent heat-transfer coefficients will range from 17 J/(m s K) in low-temperature operations to 8.5 J/(m s K) in high-temperature processes. 

Increasing the size of PAHs makes their deposition on surfaces difficult because they can neither be sublimed nor made sufficiently soluble for solution processing. A precursor route has thus been designed according to which molecules are deposited on a surface and transformed into the final disc-type adsorbate structures in a thermal solid-state reaction with the substrate surface acting as a template.1261 An exciting example is the hexaether 41 (scheme 11) which is sublimed onto a Cu-(1U) sur-... 

The SAREX process is a trailer/skid-mounted, modular system designed for on-site, in-line separation and resource recovery of oily waste sludges and contaminated soils. This process provides dewatering and thermal desorption to maximize the recovery of oil while obtaining substantial reduction in volume and contaminant concentrations. The SAREX process includes the MX-1500 centrifuge, the MX-2000 low-temperature thermal dryer, and the MX-2500 medium-temperature thermal desorber. The MX-1500 centrifuge is used to separate the solids from the... 

Of the three general categories of transport processes, heat transport gets the most attention for several reasons. First, unlike momentum transfer, it occurs in both the liquid and solid states of a material. Second, it is important not only in the processing and production of materials, but in their application and use. Ultimately, the thermal properties of a material may be the most influential design parameters in selecting a material for a specific application. In the description of heat transport properties, let us limit ourselves to conduction as the primary means of transfer, while recognizing that for some processes, convection or radiation may play a more important role. Finally, we will limit the discussion here to theoretical and empirical correlations and trends in heat transport properties. Tabulated values of thermal conductivities for a variety of materials can be found in Appendix 5. 

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