Miloslav Hartman

The study is concentrated on thermodynamic analyses of gas desulfurization process (deep removal of H₂S, COS, thiophene) by selected solid sorbents (ZnO, MnO, Ce_xO_y and La₂O₃) and on interferences caused by presence of hydrogen halides in a temperature range 500-1100 K. The results show that theoretically Ce₂O₃ and La₂O₃ are the best sorbents for sulfur compounds at temperatures over approx. 700 K. The Ce_xO_y, La₂O₃ and MnO based sorbents can suffer from significant interferences caused by higher concentrations of HCl and HF in gas phase. The thermodynamic equilibria suggest that removal of HCl (HF) by soda based sorbents at temperatures 650 – 850 K is practically without interferences from sulfur compounds. The common alkali carbonates are less suitable than the calcium based (Ca (OH)₂, CaCO₃) sorbents for deep removal of HF.

Results of an experimental study on the rate of attrition of lime catalyst/sorbent in a high-temperature, turbulent fluidized bed with quartz sand are presented. Batch measurements were conducted at 850°C in an electrically heated gasification reactor of the inner diameter of 5.1 cm with three samples of high-grade dolomitic lime of the particle size 450 μm, 715 μm, and 1060 μm, respectively. In addition to the influence of the particle size, the effect of operating (elapsed) time was investigated at different superficial gas velocities. Assuming that the attrition rate decreases exponentially with time, a simple mechanistic model, enabling the correlation of the measured experimental data, was developed. The course of the lime particles attrition is described as a function of the elapsed time, excess gas velocity, and particle size. The presented approach and the results might be applicable for the attrition of high-grade dolomitic lime, particularly in fluidized gasification of biomass.