Maximizing Combustion Efficiency Through Selection of Optimum CO Control Levels

Abstract

With the increased emphasis on improved combustion control and the availability of accurate and reliable multi-parameter combustion instrumentation, an analytical technique is needed to supplant the previous incomplete assumptions and misleading guidelines for maintaining maximum boiler efficiency. This paper will present an analytical technique for establishing an optimum value of CO to minimize thermal losses in the combustion process. The optimum value is established by finding that value of excess air which minimizes the combined thermal losses due to the sensible and latent heat losses associated with excess air, and the unburned fuel thermal losses which result from the formation of CO. This technique allows determination of an optimum value for CO for any given burner and resultant CO vs excess air relationship. Values obtained with this technique are generally much higher than the typical values of 100-300 PPM recommended in the current literature. As a result of this technique, boilers can now be evaluated analytically and operated near or at the point of maximum combustion efficiency. Implementation of such a control strategy dictates incorporation of an accurate and reliable in-situ CO monitor to maintain known safe and efficient conditions.