Study On The Influence Of Sludge Injected Into Station Boiler With Single Nozzle

In order to reduce the amount of waste sludge and protect the environment, the sludge containing92%water is injected into the boiler and co-combusted with coal after pretreatment. The combustion condition and thermodynamic efficiency in the boiler will change due to the sludge co-combustion. Moreover, the impact of corresponding slag and corrosion should also be taken into account.In the thesis, the commercial numerical software, Fluent. is used to study the effect of blending amount of sludge on temperature variation in the boiler. The simulated results are in good agreement with the in suit measured values which indicates the validation of this model. From the results, the velocity and temperature field are changed due to sludge co-combustion. The highest average temperature of the boiler decreases19-89℃compared with no sludge co-combustion when the blending amount ranges from2t/h to7t/h. The thermal efficiency of the boiler decreases0.35%when the blending amount is4t/h sludge. CO and H2are generated from the incomplete combustion of coal and hydrothermal reaction, which is resulted from sludge co-combustion. The emission of CO2increases5.6%-21.6%when the blending amount ranges from2t/h to7t/h. On the other hand, The emission of NOX decreases8.2%-40.6%when the blending amount ranges from2t/h to7t/h. From the results of on site measurement, gas temperature increases, slag as well as corrosion is found on the water wall due to the co-combustion of sludge.