燃煤锅炉改燃兰炭燃烧工艺及效益分析

Combustion process and benefit analysis on using semi-coke to replace coal in coal-fired boiler

兰炭因热值高、硫含量低的特点被广泛应用于散煤替代,燃煤锅炉改燃兰炭是实现资源合理利用、降低污染物排放和改善企业经济效益的有效途径。以河北某循环流化床锅炉改燃兰炭工程为例,燃烧系统采用掺烧灰渣的方法,解决改燃后机械未完全燃烧导致损失大和物料循环不稳定问题,确定了兰炭和灰渣的最佳掺混比为9∶1;配风系统采用控制总量并降低一次风率的方法,解决兰炭着火困难的问题,确定了最佳一次风比例为55%;换热系统采用增加锅炉尾部受热面的方法,解决因燃料热值提升较大产生的蒸汽超温和锅炉效率下降问题。改燃扩容后锅炉烟尘、SO2和NOx排放分别比原锅炉降低了73%、94%和55%,以原锅炉35 t/h的额定功率运行,每小时节约燃料成本5.51%,产吨蒸汽所需燃料成本降低6.47元。

Taking the project using semi-coke to replace coal as fuel in a circulating fluidized bed boiler in Hebei province,China as an example,the combustion system adopts the method of co-burning semi-coke and ash together,which solves the problems of large mechanical incomplete combustion loss and unstable material circulation after changing the fuels.The optimum mixing ratio of semi-coke to ash is 9∶1.The air distribution system adopts the methods of controlling the total air volume and reducing the primary air rate to solve the problem that semi-coke is difficult to ignite,and the optimal primary air ratio is determined as 55%.The heating surface at the tail of the boiler is increased to solve the problems of steam overheating and boiler efficiency declining caused by the large increase of fuel calorific value.The soot,SO2 and NOx emissions of the boiler after changing the fuels are reduced by 73%,94%and 55%,respectively compared with the original boiler,and the hourly fuel cost will reduce by 5.51%under the original boilers rated power.