Furnace ammonia and limestone injection with dry scrubbing for improved simultaneous SO.sub.X and NO.sub.X removal

An apparatus for simultaneously removing NO.sub.X and SO.sub.X from the exhaust from a furnace having a combustion region where NO.sub.X and SO.sub.X are formed, a first injection region which is at a temperature of about 2,000.degree.-2,400.degree. F. and a second injection region which is at a temperature of about 1,600.degree.-2,000.degree. F., the apparatus comprising:

• first injector means for injecting a calcium based sorbent into the first injection region in an amount sufficient to absorb at least some SO.sub.X generated in the combustion region;
• second injector means for injecting into the second region an ammonia or an ammonia precursor in an amount sufficient to react with at least some of the NO.sub.X generated in the combustion region, to produce an exhaust containing gas and particulate in the furnace;
• a dry scrubber connected to the furnace for receiving the exhaust and wherein unabsorbed SO.sub.2 reacts wit the calcium based sorbent and unreacted ammonia to produce an output;
• and
• collector means connected to the dry scrubber for receiving the output of the dry scrubber and for separating particulate from gas in the output, the collector means including an outlet for particulate and an outlet for gas, and a slurry tank connected to the outlet for particulate, for recycling sorbent to the dry scrubber.