The slagging of the biomass steam generator not only increases the workload of boiler operation, maintenance and repair, and seriously endangers the safety and economic operation, but also may force the furnace to reduce load operation or even be forced to shut down. Slagging itself is a complex physical and chemical process and has the characteristics of automatic aggravation. Once the boiler slagging occurs, the heat transfer will deteriorate due to the thermal resistance of the slag layer, and the gas temperature in the furnace and the surface temperature of the slag layer will increase. The surface of the slag layer is rough, and the slag particles are more likely to stick to it. As a result, the slagging process will intensify. The following is a brief list of the hazards caused by slagging in steam boilers.
1. After slagging on the heating surface, the heat transfer resistance will increase, the heat transfer will weaken, the heat absorbed by the working fluid will decrease, the exhaust gas temperature will increase, the exhaust heat loss will increase, and the boiler efficiency will decrease. In order to maintain the normal operation of the boiler, the air volume must be correspondingly increased while increasing the fuel volume. This increases the load of the blower and induced draft fan and increases the power consumption of the plant. Therefore, slagging significantly reduces the economic efficiency of steam boiler operation.
2. When the heating surface is slagging, in order to maintain the normal operation of the steam generator, the air volume must be increased. If the capacity of the ventilation equipment is limited, and the slagging is likely to cause partial blockage of the flue gas channel, the flue gas resistance will increase, and the air volume of the fan will be difficult to increase, so the load has to be reduced.
3. After slagging on the heated surface, the flue gas temperature at the outlet of the furnace rises, resulting in an increase in the overheated temperature, and the thermal deviation caused by slagging may easily cause overheating damage to the superheater. At this time, in order to maintain the overheated temperature and protect the reheater, it is also necessary to limit the load during exercise.
4. Slagging at the burner nozzle changes the airflow structure of the burner outlet, which destroys the aerodynamic working conditions in the furnace and affects the combustion process. When the slagging orifice is severely clogged, the steam boiler has to run at a reduced load or be forced to shut down.
5. The slagging of the water wall will cause uneven heating of all parts, which will adversely affect the safety of natural circulation water circulation and the thermal deviation of the control flowing water wall, and may cause damage to the water wall tube.