Experimental Study on the Performance Impact for Sludge Co-combustion in Power Plant Boiler
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 8 000 kJ/kg.After the co-combustion of fired sewage sludge,the fineness of pulverized coal does not change while the overall tem-perature level of the furnace decreases.The co-combustion of fired sewage sludge helps to reduce the a-mount of original nitrogen oxides produced at the economizer outlet,and the higher proportion of co-com-bustion,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 H2S in the near-wall area of water wall shows a deteriorating trend.After the co-combustion 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 co-combustion 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 long-term burning of dried sludge,the frequency of coal blocking in raw coal bunker and coal feeder are increased.The sludge com-position has a great influence on the dust collector system and the desulfurization system.In order to real-ize 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.
dried sewage sludgesludge co-combustionboiler thermal efficiencyreducing gasheat loss of dry flue gas
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