Three-stage process for burning fuel containing sulfur to reduce emission of particulates and sulfur-containing gases

A three-stage process for burning a particulated carbonaceous fuel containing sulfur and ash-forming materials comprising:

• (a) forming a slurry of said particulated carbonaceous fuel, water and an additive capable of reacting with said sulfur to form one or more removable compounds;
• (b) burning said slurry in a first combustion stage with less than 75% theoretical air at a temperature below the melting temperature of ash in said fuel to form said removable sulfur-containing compounds;
• (c) removing said sulfur-containing compounds;
• (d) burning combustible materials from said first stage in a second combustion stage with less than 100% of the theoretical air needed for the combustible materials from said first stage, at a temperature above the melting point of ash in said combustible materials from said first stage;
• (e) removing said ash as a slag;
• and
• (f) burning combustible materials from said second stage in a third combustion stage with an excess of air whereby the emissions from said third stage of sulfur-containing gases and particulates will be substantially lowered.

A three-stage process for burning a particulated carbonaceous fuel containing sulfur and ash-forming materials comprising:

• (a) forming a slurry of said particulated carbonaceous fuel, water and an additive capable of reacting with said sulfur to form one or more removable compounds;
• (b) burning said slurry in a first combustion stage with less than 75% theoretical air at a temperature below the melting temperature of ash in said fuel to form said removable sulfur-containing compounds;
• (c) removing at least a portion of said sulfur-containing compounds from said first combustion stage;
• (d) passing the remainder of the materials from said first combustion stage to a second combustion stage;
• (e) burning combustible materials from said first stage in a second combustion stage with less than 100% of the theoretical air needed for the combustible materials from said first stage at a temperature above the melting point of ash in said combustible materials from said first stage;
• (f) removing said ash as a slag;
• and
• (g) burning combustible materials from said second stage in a third combustion stage with an excess of air whereby the emissions from said third stage of sulfur-containing gases and particulates will be substantially lowered.