Numerical Simulation Of Mixed Combustion Of Pulverized Coal And Blast Furnace Gas In 350MW Utility Boiler

As an important by-product gas, Blast furnace gas efficient and rational use have a significant effect on the iron and steel enterprises economic and energy saving. But in practice, blast furnace gas shortcoming that low calorific value, inert gas content is too much, combustion instability limits its application scope. Currently, the method some steel companies taken that BFG and the pulverized both as fuel to make power solve the problem. However, BFG poor combustion performance influences the combustion in the boiler. Based on the above considerations, this paper has an analysis on flow field, temperature field and components of combustion through numerical simulation method.Firstly, this paper analysis four cases that fuel respectively include 0%,20%,30%,40% BFG. According to the comparison, we can see adding BFG in the combustion have a significant effect on flow field, temperature field and the distribution of the combustion components. The full coal fired maximum average temperature on boiler cross section 100k higher than the blending combustion, which show that the temperature in the furnace significantly reduced after adding BFG. In addition this paper analysis the upper flow field, temperature field. Since the plant don’t take some measures to eliminate rotation, in the upper, strong residual rotation is remained and becoming more and more strong with the increase of blending amount of BFG. This paper think blending 20% BFG is most appropriate with the comprehensive analysis of furnace export condition.In addition, the simulation of No.1 boiler after low NOX emission modifications is made, while the simulation contain two cases,the one is that coke oven gas vents as OFA vents, the other one is that new vents as OFA vents. In the first case, spout region formed good reducing atmosphere by air classification method, but the OFA sent into furnace so early that the coal don’t burnout in the reducing atmosphere leading to the inhibition of NOx generated has little effect. In the second method, the generation of NOx is reduced. Combined with comprehensive analysis of furnace export condition, OFA is 15%～20% of all wind is perfect.