矿井乏风通入燃煤锅炉混烧的最佳配伍参数研究*

为优化矿井乏风通入燃煤锅炉的配伍参数，采用Design-Expert软件的响应面分析法，以燃煤锅炉的主燃区顶端水平面平均温度和燃尽区顶端水平面的NO平均浓度为评价指标，按照3因素3水平正交组合设计试验方法，研究乏风中甲烷体积分数、燃尽风风率以及锅炉负荷的不同配伍比例对燃煤锅炉的变化影响，并建立3个因素的评价指标数学模型，分析各因素的主次关系和因素间交互作用大小，使得锅炉中煤粉放热量和氮氧化物的生成量均达到理想水平。研究结果表明:单因素中燃尽风风率对温度的影响最大，锅炉负荷对NO生成影响最大，交互作用下燃尽风风率与锅炉负荷对温度的影响和对NO浓度的影响均最显著。最优配伍参数为:乏风中甲烷浓度0.25%、燃尽风风率33.51%、锅炉负荷564.11 MW，在此参数下的温度响应值为1 691.41、NO浓度响应值为0.000 315 89。在最优参数下得到的预测值与试验值的误差在允许范围内，即吻合度较好，可为四角切圆锅炉掺烧矿井乏风提供参考。

Study on optimum compatibility parameters of mixed combustion with ventilation air methane into coal-fired boiler

In order to optimize the compatibility parameters of ventilation air methane (VAM) into the coal-fired boiler,the response surface analysis method of Design-Expert software was used.Taking the average temperature of the top horizontal plane of the main combustion zone and the average molar mass fraction of NO at the top horizontal plane of the over-fire zone of coal-fired boiler as the evaluation indexes,the test method was designed according to the orthogonal combination of three factors and three levels,and the influence of methane volume fraction in VAM,over-fire air (OFA) rate and different compatibility ratios of boiler load on the change of coal-fired boiler was studied.The mathematical model of evaluation indexes on three factors was established,and the primary and secondary relationship of each factor and the interaction between factors were analyzed,so that both the heat release of pulverized coal and the generation of nitrogen oxides in the boiler reached an ideal level.The results showed that for the single factor,the OFA rate had the greatest influence on the temperature,and the boiler load had the greatest influence on the NO generation.Under the interaction effect,both the influence of OFA rate and boiler load on the temperature and NO concentration were the most significant.The optimum compatibility parameters were the methane concentration in VAM as 0.25%,the OFA rate as 33.51%,and the boiler load as 564.11 MW.Under these parameters,the temperature response value was 1 691.41 and the NO concentration response value was 0.000 315 89.The error between the predicted value and experimental value under the optimal parameters was in the allowable range,namely the goodness of fit was better,which provides reference for the mixed combustion of VAM in the four corners tangentially fired boilers.