81-89 Possibility of nox emission reduction from combustion process using sewage sludge gasification gas as an additional fuel

Abstract

In the paper, a numerical simulation of the co-combustion process of sewage sludge gasification syngas in a hard coal-fired boiler was done. Two different syngases (SSl and SS2) were taken in consideration. Additional (reburning) fuel was injected into the combustion chamber, which was modeled as a plug flow reactor (PFR). The molar flow rates ratio of reburning fuel is assumed to be 5.0%, 7.5%, 10.0%, 12.5% and 15.0% of the whole exhaust. The simulations were conducted for constant pressure equal to latm for temperatures range from 600 to 1400 K. It was assumed that a flue gases which enters the reburning zone contains 300 ppm of NO and that during combustion only NO is formed without other NO1. Results show that that gas from sewage sludge gasification gives reburning efficiency of up to 90%. Calculation shows also an optimum value of temperature reburning for gas from sewage sludge gasification which is equal to 1200 K. The type of the sewage sludge has no strong influence on the NO reduction. © C Copyright by Polish Academy of Sciences and Institute of Environmental Engineering of the Polish Academy of Sciences, Zabrze, Poland 2012.