Experimental study on multi‐fuel combustion of lean coal and by‐product gas in a 75t/h tangentially‐fired boiler

Abstract

By-product gas is used as an alternative energy for steel mills to relieve the pressure of the fossil fuel crisis. In order to study the influence of blending by-product gas on boiler operation, the multi-fuel combustion experiments on the mixture of coke oven gas (COG), blast furnace gas (BFG), and lean coal were carried out in a 75t/h multifuel combustion boiler so as to determine the most balanced fuel formula. The results indicated that the mixed combustion of COG and lean coal could improve the boiler efficiency. However, the balance of by-product gas utilization in steel mills was destroyed for not using BFG. Although mixed combustion of BFG and COG improved the boiler efficiency, the boiler could only be operated under low load because of lower furnace temperature. After applying the most balanced flue ratio of BFG, COG, and lean coal, with heat value rations of 35%, 35%, and 30%, respectively, the efficiency of the boiler became 77.21%. The flue gas temperature lowered 4.5 C and the carbon content of fly ash and boiler slag were reduced by 1.06% and 1.09%, respectively. As a result, the stand coal consumption of the boiler decreased by 226.1 kg/h with the ratio of coal saving being 3.3%.