Removing SOx, CO and NOx from flue gases

In a hydrocarbon fueled hazardous waste incinerator wherein an oxygen-containing gas is fed to a combustor for combustion of a hydrocarbon fuel to water and carbon dioxide, a method of removing sulfur oxide, carbon monoxide and nitrogen oxide from a flue gas stream from said combustor using said fuel and an oxygen-containing gas comprising the steps of:

• combusting said fuel in said combustor with an amount of oxygen-containing gas to convert all sulfur-containing species in said fuel to sulfur oxide and provide a sulfur oxide containing gas stream, and to partially convert said fuel to water and carbon dioxide, the amount of said oxygen-containing gas supplied to said combustor being from about 95% to about 110% of said stoichiometric amount to convert said fuel to carbon dioxide, the amount of said oxygen-containing gas being selected to maintain the concentration of carbon monoxide in said sulfur oxide containing gas stream at from about 500 ppm to about 5,000 ppm, the amount of nitrogen oxide in said sulfur oxide containing gas stream being an inverse function of the amount of carbon monoxide therein;
• contacting said sulfur oxide containing gas stream and sufficient additional air with a solid adsorbent bed for adsorbing thereon the sulfur oxides in the form of inorganic sulfates or sulfur oxides or combinations thereof, the solid adsorbent containing a catalytic oxidation promoter for oxidizing the carbon monoxide in said sulfur oxide containing gas stream to carbon dioxide, thus forming a sulfur oxide and carbon monoxide depleted stream with the consequential reduced amount of nitrogen oxide for disposal;
• and
• contacting said adsorbent bed with a reducing gas stream for regenerating said adsorbent bed by reducing said retained inorganic sulfates or sulfur oxides or combinations thereof to hydrogen sulfide and/or sulfur dioxide, and thereby forming a hydrogen sulfide and/or sulfur dioxide bearing stream.

In a hydrocarbon fueled mineral or metallurgical plant wherein an oxygen-containing gas is fed to a combustor for combustion of a hydrocarbon fuel to water and carbon dioxide, a method of removing sulfur oxide, carbon monoxide and nitrogen oxide from a flue gas stream from said combustor using said fuel and an oxygen-containing gas comprising the steps of:

• combusting said fuel in said combustor with an amount of oxygen-containing gas to convert all sulfur-containing species in said fuel to sulfur oxide and provide a sulfur oxide containing gas stream, and to partially convert said fuel to water and carbon dioxide, the amount of said oxygen-containing gas supplied to said combustor being from about 95% to about 110% of said stoichiometric amount to convert said fuel to carbon dioxide, the amount of said oxygen-containing gas being selected to maintain the concentration of carbon monoxide in said sulfur oxide containing gas stream at from about 500 ppm to about 5,000 ppm, the amount of nitrogen oxide in said sulfur oxide containing gas stream being an inverse function of the amount of carbon monoxide therein;
• contacting said sulfur oxide containing gas stream and sufficient additional air with a solid adsorbent bed for adsorbing thereon the sulfur oxides in the form of inorganic sulfates or sulfur oxides or combinations thereof, the solid adsorbent containing a catalytic oxidation promoter for oxidizing the carbon monoxide in said sulfur oxide containing gas stream to carbon dioxide, thus forming a sulfur oxide and carbon monoxide depleted stream with the consequential reduced amount of nitrogen oxide for disposal;
• and
• contacting said adsorbent bed with a reducing gas stream for regenerating said adsorbent bed by reducing said retained inorganic sulfates or sulfur oxides or combinations thereof to hydrogen sulfide and/or sulfur dioxide, and thereby forming a hydrogen sulfide and/or sulfur dioxide bearing stream.