Conditioning of Fly Ash with Sulfur Trioxide and Ammonia.

摘要

The report summarizes research on the conditioning of fly ash in coal-burning electric power stations with two flue-gas additives--sulfur trioxide and ammonia. It presents experimental data on the use of these additives to improve the efficiency of electrostatic precipitation of fly ash by adjusting the electrical resistivity of the ash and by other less widely recognized mechanisms. The report shows that the primary role of sulfur trioxide is lowering resistivity from the excessive values found with ash from low-sulfur coals. It also indicates that the role of ammonia does not involve a change in resistivity,despite findings to the contrary by other investigators. At least for the specific circumstances investigated,the research data indicate that conditioning by ammonia involves a space-charge enhancement of the electric field in the interelectrode space of a precipitator and,sometimes additionally,an increase in the cohesiveness of the collected ash. The report addresses both the theoretical aspects of conditioning mechanisms,and such practical matters as the effectiveness of each agent as a function of the concentration added,the facilities used for adding the agent,the chemical composition of the ash treated,and the temperature of the ash during conditioning and precipitation.