掺烧污泥对电站锅炉性能影响的试验研究

Experimental Study on the Performance Impact for Sludge Co-combustion in Power Plant Boiler

为了考察不同污泥掺烧比例对煤粉锅炉性能的影响,对某电站锅炉进行了掺烧干化污泥的工程试验。通过性能试验的对比,分析了污泥掺烧对煤质、煤粉细度、炉膛温度、氮氧化物、水冷壁还原性气体、锅炉热效率和汽水系统等的影响。结果表明:干化后的城市污泥、印染污泥热值约为8000 kJ/kg;掺烧污泥后,煤粉细度基本没有变化,炉膛整体温度水平降低;掺烧污泥有助于减少省煤器出口原始氮氧化物生成量,且掺烧比例越高,氮氧化物生成量呈下降趋势;由于污泥的硫份高于一般煤种,同时挥发分较早析出消耗了主燃区氧量,掺烧污泥后水冷壁近壁区还原性气体CO和H_(2)S质量浓度呈现增大趋势;掺烧干化污泥后,飞灰大渣含碳量无明显的变化规律,CO未完全热损失呈现增大趋势,干烟气热损失增大的趋势最明显;475 MW负荷下,干化污泥实际掺烧比例为2.5%,锅炉热效率下降0.23%;630 MW负荷下,干化污泥实际掺烧比例为6.0%,锅炉热效率下降0.22%;掺烧污泥后,主再热汽温、主再热压力没有变化,再热减温水量有所上升;长期掺烧干化污泥后,原煤仓、给煤机堵煤的频次增加;污泥成分对除尘器系统、脱硫系统的影响较大;为了实现污泥资源化利用,促进火电机组的可持续发展,煤粉锅炉掺烧干化污泥的影响在可控范围内。

In order to investigate the influence of different sludge blending ratios on the performance of pulverized coal-fired boiler,an engineering test of dried sewage sludge co-combustion was carried out on a power plant boiler.By the comparison of performance tests,the effects of co-combustion of sludge on coal quality,pulverized coal fineness,furnace temperature,nitrogen oxides,reducing gas concentration near the water wall,boiler thermal efficiency and steam-water system were analyzed.The results show that the calorific value of dried municipal sludge and dyeing sludge is about 8000 kJ/kg.After the co-combustion of fired sewage sludge,the fineness of pulverized coal does not change while the overall temperature level of the furnace decreases.The co-combustion of fired sewage sludge helps to reduce the amount of original nitrogen oxides produced at the economizer outlet,and the higher proportion of co-combustion,the greater downward trend of nitrogen oxide production.Since the sulfur content of sludge is higher than that of common coal types,and the earlier precipitation of volatile fraction consumes oxygen in the main combustion zone,the mass concentration of reducing gas of CO and H_(2)S in the near-wall area of water wall shows a deteriorating trend.After the cocombustion of dried sewage sludge,there was no obvious change in the carbon content of fly ash and residue,while the incomplete heat loss of CO shows an increasing trend,and the increasing trend of the heat loss of dry flue gas is the most obvious.Under the load of 475 MW,the actural blending proportion of dried sewage sludge is 2.5%,while the thermal efficiency of boiler decreases by 0.23%.Under the load of 630 MW,the actural blending proportion of dried sewage sludge is 6.0%,while the thermal efficiency of boiler decreases by 0.22%.After the cocombustion of sewage sludge,the main reheat steam temperature and main reheat steam pressure have no change,while the amount of reheat desuperheating water increases.After longterm burning of dried sludge,the frequency of coal blocking in raw coal bunker and coal feeder are increased.The sludge composition has a great influence on the dust collector system and the desulfurization system.In order to realize the resource utilization of sludge and promote the sustainable development of thermal power units,the influence of co-firing dried sludge in pulverized coal boiler is within the controllable range.