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  Cost of Selective Catalytic Reduction (SCR) Application for NOx Control on Coal-Fired Boilers (EPA/600/R-01/087) October 2001
Project Summary

This report provides a methodology for estimating costs associated with retrofit applications of selective catalytic reduction (SCR) technology on coal-fired boilers. SCR is a control technology for post-combustion nitrogen oxides (NOx) and is capable of providing NOx reductions in excess of 90 percent.

With SCR, NOx reductions are achieved by injecting ammonia into the flue gas, which then passes through layers of catalyst in a reactor. The ammonia and NOx react on the surface of the catalyst, forming molecular nitrogen and water. In the United States, SCR has been applied mainly to electrical utility boilers firing coal and natural gas and ranging in capacity from 25 to 800 megawatts (MW).

The costing methodology presented in this report is applicable to SCR retrofits on coal-fired boilers ranging in capacity from 100 MW to approximately 850 MW and with design efficiencies greater than 80 percent and up to 95 percent of NOx removal. The cost equations and variables used in the methodology are based on information obtained from SCR system suppliers and reflect experience gained from over 200 SCR applications. It is noted, however, that the cost estimates for typical SCR applications that this methodology can provide cannot replace the detailed site-specific engineering cost studies or cost quotations that are developed by SCR system suppliers.


Ravi K. Srivastava

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