Furnace ammonia and limestone injection with dry scrubbing for improved simultaneous SOX and NOX removal

Claim 1

A process for the simultaneous removal of NO X and SO X from the exhaust of a furnace having a combustion region where NO X and SO X are formed, a first injection region at a temperature of about 2,000°-2,400° F. and a second injection region at a temperature of about 1,600°-2,000° F., the process comprising the steps of: injecting a calcium based sorbent into the first injection region in an amount sufficient to absorb at least some SO X generated in the combustion region; injecting ammonia or ammonia precursor into the second injection region in an amount sufficient to react with and reduce at least some of the NO X generated in the combustion region, to produce an exhaust containing gas and particulate; supplying the exhaust to a dry scrubber where unabsorbed SO X reacts with the calcium based sorbent and unreacted ammonia; supplying an output from the dry scrubber to a particulate collector for separating particulate from gas; and recycling at least some of the particulate to a slurry tank where unused calcium containing sorbent is returned to the dry scrubber to absorb additional SO 2 .

Claim 6

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

Claim 7

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