Control of hazardous air emissions from wood-fired boilers

Hazardous air pollutants are generated by the incomplete combustion of fuels. Emissions are reduced by controlling furnace exit temperatures and establishing minimum residence times. Monitoring carbon monoxide (CO) emissions is important since the amount of carbon monoxide emitted represents the degree of complete combustion which in turn represents the amount of hazardous air pollutants being generated. Wisconsin monitored carbon monoxide emissions from six commercial and institutional wood-fired boilers to evaluate emissions and control strategies. The continuous monitoring data indicate frequent, high amplitude variations in emissions from each source. This highlights the need to control operations to reduce variation in emissions. It also demonstrates a problem with carbon monoxide monitoring strategies that rely on periodic sampling, and offers a challenge for developing more representative and useful carbon monoxide monitoring protocols. This paper presents one regulatory strategy that provides an incentive for operators to reduce emission variations and the resulting hazardous emissions.