REDUCING FOULING FROM BROWN COALS BY SODIUM-BINDING ADDITIVES

The paper reports on methods to control medium-temperature fouling in brown coal-fired power utilities. Binding of sodium is crucial to prev ent deposition of condensable sodium salts in the convection sections of pulverised coal-fired boilers. Experiments using mixtures of candid ate additives with different sodium compounds were conducted in a drop tube furnace. Experiments showed that sodium could be effectively cap tured by clay-type mineral additives, particularly kaolin. The results obtained with inorganic mixtures complement our earlier data using co al particles pre-treated with alumina. For pulverised coal conversion processes based on Victorian brown coal, 10-20 mu m kaolin making up 2 -3 wt.% of the feed was estimated to effectively reduce fouling. (C) 1 998 Elsevier Science B.V. All rights reserved.