Implementation and economic analysis of MILD combustion in a lab-scale boiler

In this paper design and implementation of a MILD combustion system in a 100 kW boiler was investigated from technical and economic viewpoints. The main objective of this study is determination of the factors affecting the stability of the combustion regimes in a typical domestic utility boiler, leading in simultaneous thermal efficiency enhancement and emission reduction. In particular, the so-called MILD combustion was established in a conventional boiler equipped with an ordinary premixed burner without requiring to replace with expensive modern burners. In the experiments, the qualitative and quantitative features of MILD regime such as uniform temperature distribution in the combustion chamber, volumetric and weakened flame, increased efficiency and decreased NOx emissions were achieved. The results showed a 10% fuel saving as well as 13% reduction in NOx. In addition, the economic evaluation of presented method to establish MILD combustion was performed using the net present value and payback period measures. The analysis results suggest that investment in the MILD system retrofitting plan is cost-effective and economically attractive in similar cases.