Optimizing the Excess Air Ratio of Coal-Fired Boiler

This paper investigates on optimization problem of excess air ratio of coal-fired boiler by using the following three-step strategy. Firstly, the net efficiency of boiler (NEB) and the Cost of Boiler Heat Production (CBHP) are both taken as the objective functions, and the excess air ratio (EAR) is taken as the input variable. Secondly, the relationship between the objective functions and the EAR is established based on the model of variable working conditions. Finally, the implicit enumeration algorithm is employed to obtain the optimal EAR value that optimizing the objective functions, under the constraints that the EAR must be committed. Three cases of boiler load, such as 100%, 75% and 50%, are studied. The results show that NEB has the optimal value by using different EAR values. The cost of the boiler thermo genesis is affected not only by the EAR, but also by the coal price and the pool purchase price of thermal power plants. When the pool purchase price is fixed, the EAR has the decreasing trend corresponding to the lowest cost of the boiler thermo genesis in keeping with the economics laws. The calculation result was strongly by the result of the performance optimization test of the boiler.