A study is reported of the controlled decompositions of a series of inorganic sulfates and their common hydrates, carried out in a thermogravimetric analyzer (TGA), a differential scanning calorimeter (DSC), and a differential thermal analyzer (DTA). Various sample sizes, heating rates, and ambient atmospheres were used to demonstrate their influence on the results. The purposes of this study were (1) to reveal intermediate compounds, (2) to determine the stable temperature range of each compound, and (3) to measure reaction kinetics. In addition, several solid additives: carbon, metal oxides, and sodium chloride, were demonstrated to have catalytic effects to varying degrees for the different salts.
A preliminary economic analysis has indicated that the making of acetylene, via a kiln calcium carbide process, can be cost competitive with ethylene if used to produce vinyl chloride monomer. The work presented here includes (1) the kinetics of carbide formation from reduction of lime, (2) the characterization of this carbide product, and (3) a process demonstration in a prototype bench-scale rotary kiln. From the study of the reduction chemistry, it was found that reduction rates of lime to carbide are fast, needing less than 30 min to achieve conversions of 50-80% (1740-1870 °C). An increase of carbon monoxide pressure in the surrounding atmosphere tends to inhibit the reaction.
A model is derived for solids mixing and material transport in a continucus flow rotary dryer or reactor. Detailed analysis of the particle motions in the turnover process provides an opportunity to apply well‐known reactor models to several subregions and to relate the overall results to different design geometries and operating conditions. The essential parameters of the model are the number of stages, the volume fractions of mixed flow and plug flow in each stage, the recycle ratio and the bypass ratio.
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