Carbonation ash reactivation process and system for combined SOx and NOx removal

Abstract

The present invention includes methods and apparatus useful in the removal of air pollutants. More specifically, this invention relates to methods and apparatus useful in mitigating major air pollutants (SO x and NO x ) and trace toxins from coal-fired combustors. Using a method or apparatus of the present invention, a coal-fired combustor may be retrofitted to accommodate combined SO x /NO x removal technology for solid waste reduction and environmentally responsible utilization of dry flue gas (FGD) desulfurization product. The combined SO x /NO x control technology may integrate enhanced removal of SO 2 at high to medium temperatures using a desulfurization process of the present invention with selective catalytic reduction technology for NO x . The reactivation of spent sorbent and dry FGD product may result in a more complete utilization of the ash and sorbent in the reduction of SO 2 emissions, thereby reducing significantly the amount of sorbent used and the volume of by-product generated. Modifications to a power plant may result in significant changes to the waste stream. Based upon the process for dry FGD product reactivation to achieve enhanced SO 2 removal and SCR for NO x removal, it may be possible to remove both sulfur and nitrogen oxides from high sulfur coal. The process is modular in nature (different components of the process can be by-passed as and when the need arises) and thus may have great flexibility and be applicable to various operating conditions.

What is claimed is: Method of Preparing a Sorbent from Limestone, Lime or Slaked Lime Generated from the Removal of SOx from a Gaseous Waste Stream from Coal Combustion  
     
         1 . A method of preparing a sorbent from limestone, lime or slaked lime generated from the removal of SO x  from a gaseous waste stream from coal combustion, said method comprising: 
 (a) obtaining said limestone, lime or slaked lime; and    (b) admixing carbon dioxide and water with said limestone, lime or slaked lime so as to carbonate said limestone, lime or slaked lime, so as to produce a carbonated sorbent.    
     
     
         2 . A sorbent produced in accordance with the method of claim  1 .