利用循环流化床(CFB)锅炉掺烧一定比例污泥是减量化、无害化和资源化处理污泥的有效方式。为了解污泥掺烧对大型电站CFB锅炉物料平衡和运行性能的影响，以某330 MWe亚临界CFB锅炉为研究对象，借助一维CFB数学模型对其掺烧污泥后的物料平衡特性进行预测和分析，然后结合实炉运行数据讨论掺烧对锅炉性能的影响。模型计算结果表明，在原煤矸石和煤泥混合燃料中(煤泥质量分数为15%)，掺入10%污泥替换一部分煤矸石后，飞灰和底渣粒度变化很小，而循环灰粒度略微增大；循环流率由9.2 kg/(m2·s)提高至11.8 kg/(m2·s)，提高了近30%；稀相区平均压降即颗粒悬浮浓度增大约35%；飞灰占总灰渣份额增加约1.5个百分点；同时床料颗粒在炉膛内的停留时间有所延长。在不同锅炉负荷(50%～100%)下的实测结果均显示，掺烧10%污泥后，床温下降10 ℃左右；排烟温度升高3 ℃以内；低温过热器及低温再热器出口蒸气温度有所提高，大部分工况下温升在10 ℃以内；而炉内屏式过热器出口蒸气温度则略有降低，降幅为2～15 ℃。模型和实炉运行结果表明，掺烧少量污泥有利于改善CFB锅炉物料循环性能，尾部烟道对流换热增强，而炉内屏式过热器传热系数有所降低。但总体上看，在较宽负荷范围内，当污泥掺烧比例较低时，锅炉蒸气参数等变化较小，对整体运行性能影响不大。

Co-combustion of sludge and other fuels such as coal in the circulating fluidized bed (CFB) boiler is an effective way to reduce,harmless and resource sludge treatment. To understand the influence of sludge co-combustion on the material balance and operation performance of a large-scale CFB boiler,taking a 330 MWe subcritical CFB boiler as the research object,the material balance characteristics after sludge mixed combustion were predicted and analyzed with the help of one-dimensional CFB mathematical model. Then,the boiler operation performance under co-combustion condition was analyzed in combination with some field test data. Model calculation results show that in the mixed fuel of raw coal gangue and coal slime (the mass fraction of coal slime is 15%),if 10% mass fraction of sludge is added by replacing part of the coal gangue,the particle size of fly ash and bottom ash will change little,while the circulating ash size may be slightly increased. Meanwhile,the solid circulation rate will increase by nearly 30%,from 9.2 kg/(m2·s) to 11.8 kg/(m2·s),the average pressure drop across dilute phase zone as well as the particle suspension density will increase by about 35%,and the share of fly ash in the total discharging ash will increase by about 1.5 percentage points. Besides,the residence time of solid particles inside furnace can also be extended. In addition,the field test results under different boiler loads (from 50% to 100% load) reveal that when 10% mass fraction of sludge is mixed in the feeding fuel,the bed temperature has dropped by about 10 ℃,the exhaust gas temperature has raised within 3 ℃. The steam temperatures at the outlet of primary superheater and primary reheater have increased,while the temperature [JP2rise is within 10 ℃ at most boiler loads,and the outlet steam temperature of in-furnace platen superheater has slightly decreased by 2-15 ℃. The results in this paper indicate that the co-combustion of sludge with coal is beneficial to improving the solid circulation performance of the CFB boiler to some extent,moreover,the convection heat transfer in tail flue may be enhanced,while the heat transfer coefficient of the platen heating surfaces in furnace may decrease. However,on the whole,for the wide load range,if the blending ratio of sludge in the mixed fuel is not high,the changes of boiler steam parameters are small,which has little impact on the overall operation performance.

0 引言

1 锅炉结构及主要参数

2 污泥掺烧对锅炉物料平衡影响

   2.1 一维CFB模型简述和燃料性质

   2.2 模型计算结果

3 污泥掺烧对锅炉性能的影响

4 结论