2 Matching Results

Search Results

Advanced search parameters have been applied.

Influence of changing particle structure on the rate of gas-solid gasification reactions. Final report, July 1981-March 1984

Description: The objetive of this work is to determine the changes in the particle structure of coal as it undergoes the carbon/carbon dioxide reaction (C + CO/sub 2/ ..-->.. 2CO). Char was produced by heating the coal at a rate of 25/sup 0/C/min to the reaction temperatures of 800/sup 0/C, 900/sup 0/C, 1000/sup 0/C and 1100/sup 0/C. The changes in surface area and effective diffusivity as a result of devolitization were determined. Changes in effective diffusivity and surface area as a function of conversion have been measured for reactions conducted at 800, 900, 1000 and 1100/sup 0/C for Wyodak coal char. The surface areas exhibit a maximum as a function of conversion in all cases. For the reaction at 1000/sup 0/C the maximum in surface area is greater than the maxima determined at all other reaction temperatures. Thermogravimetric rate data were obtained for five coal chars; Wyodak, Wilcox, Cimmeron, Illinois number 6 and Pittsburgh number 6 over the temperature range 800-1100/sup 0/C. All coal chars exhibit a maximum in reaction rate. Five different models for gas-solid reactions were evaluated. The Bhatia/Perlmutter model seems to best represent the data. 129 references, 67 figures, 37 tables.
Date: April 4, 1984
Partner: UNT Libraries Government Documents Department

Low-cost solar array project. Task I. Silicon material: investigation of the hydrogenation of SiCl/sub 4/. Third quarterly report

Description: A laboratory stainless steel reactor has been constructed and installed to study the hydrogenation of SiCl/sub 4/, 3 SiCl/sub 4/ + 2 H/sub 2/ + Si reversible arrow 4 SiHCl/sub 3/. The reactor is designed to operate at pressure up to 500 psig which is the proposed operating pressure range of the Union Carbide EPSDU; silane-to-silicon process. Series of experiments were carried out to measure the reaction kinetics. The effect of reactor temperature on the rate of the hydrogenation of SiCl/sub 4/ to SiHCl/sub 3/ was measured at 400, 450, 500 and 550/sup 0/C. As expected, the reaction rate increases rapidly with increasing reactor temperature. The reaction rate and SiHCl/sub 3/ conversion were studied as functions of hydrogen and SiCl/sub 4/ concentrations at H/sub 2//SiCl/sub 4/ ratios of 1.0 and 2.8. Higher H/sub 2/SiCl/sub 4/ ratio produces a higher SiHCl/sub 3/ conversion per pass while the reaction rate remains approximately the same. The effect of reactor pressure on the rate of the hydrogenation reaction is most interesting. The rate of approaching equilibrium at higher reactor pressure (500 psig) is somewhat slower than those at lower reactor pressure (300 psig). In general, the 500 psig experimental data confirm previous estimated results which were obtained by extrapolating from lower reactor pressure data. Results of these experimental data show that the highest product SiHCl/sub 3/ output for a given reactor size is achievable by operating the hydrogenation process at maximum reactor temperature and pressure.
Date: January 4, 1980
Creator: Mui, J. Y. P.
Partner: UNT Libraries Government Documents Department