1. Oxygen Amount
The total air volume entering the furnace is closely related to the thermal efficiency of the boiler. Excessive total air volume increases exhaust heat loss; insufficient total air volume results in incomplete combustion of the pulverized coal, increasing the CO content, fly ash combustible content, and slag combustible content in the flue gas, leading to increased chemical and mechanical incomplete combustion losses. The total air volume also affects the main steam temperature and reheat steam temperature. Therefore, selecting an appropriate total air volume entering the furnace can minimize total heat loss, maximize boiler thermal efficiency, and maintain a high steam temperature at low loads.
2. Furnace-Windbox Pressure Differential
Under the conditions of constant boiler load and furnace outlet oxygen content, the furnace-windbox pressure differential affects the ratio of the auxiliary air, fuel air, and ember air volumes. This ratio significantly affects the stability and burnability of pulverized coal combustion, as well as NOx emissions. Therefore, selecting an appropriate furnace-windbox pressure differential improves boiler safety and economic efficiency. 3. Overburn Air Volume
The top layer of the burner houses the ember air nozzles. The ember air serves to achieve staged combustion, reduce thermal NOx generation, and replenish oxygen required in the later stages of combustion. The overburn air volume affects NOx emissions and the extent of carbon particle combustion. This test only considers the effect of the overburn air volume on boiler combustion.
4. Burner Swing Angle
The burner nozzles are designed to swing upward and downward, primarily adjusting the reheat and superheat steam temperatures by changing the center height of the furnace flame. However, changes in the center height of the flame have a certain impact on the combustion of pulverized coal. Upward swing of the burner increases the combustible content of fly ash, reduces boiler efficiency, and increases the amount of desuperheating water.
5. Primary Air Speed
The unit was operating at a 600MW load, and other boiler operating parameters remained unchanged. The primary air nozzle speed was varied by changing the pulverizer inlet air volume. Due to limitations in the pulverizing system, the primary air speed was difficult to vary widely, resulting in little change in boiler thermal efficiency. This indicates that small changes in the primary air speed have little impact on boiler thermal efficiency. 6. Pulverized Coal Fineness
Reducing pulverized coal fineness reduces the combustible content of fly ash and slag, improving boiler thermal efficiency.
7. Grinding Method
Combining the operation of separate pulverizers results in minimal differences in boiler thermal efficiency, but significantly impacts steam temperature.
1. Oxygen Amount
The total air volume entering the furnace is closely related to the thermal efficiency of the boiler. Excessive total air volume increases exhaust heat loss; insufficient total air volume results in incomplete combustion of the pulverized coal, increasing the CO content, fly ash combustible content, and slag combustible content in the flue gas, leading to increased chemical and mechanical incomplete combustion losses. The total air volume also affects the main steam temperature and reheat steam temperature. Therefore, selecting an appropriate total air volume entering the furnace can minimize total heat loss, maximize boiler thermal efficiency, and maintain a high steam temperature at low loads.
2. Furnace-Windbox Pressure Differential
Under the conditions of constant boiler load and furnace outlet oxygen content, the furnace-windbox pressure differential affects the ratio of the auxiliary air, fuel air, and ember air volumes. This ratio significantly affects the stability and burnability of pulverized coal combustion, as well as NOx emissions. Therefore, selecting an appropriate furnace-windbox pressure differential improves boiler safety and economic efficiency. 3. Overburn Air Volume
The top layer of the burner houses the ember air nozzles. The ember air serves to achieve staged combustion, reduce thermal NOx generation, and replenish oxygen required in the later stages of combustion. The overburn air volume affects NOx emissions and the extent of carbon particle combustion. This test only considers the effect of the overburn air volume on boiler combustion.
4. Burner Swing Angle
The burner nozzles are designed to swing upward and downward, primarily adjusting the reheat and superheat steam temperatures by changing the center height of the furnace flame. However, changes in the center height of the flame have a certain impact on the combustion of pulverized coal. Upward swing of the burner increases the combustible content of fly ash, reduces boiler efficiency, and increases the amount of desuperheating water.
5. Primary Air Speed
The unit was operating at a 600MW load, and other boiler operating parameters remained unchanged. The primary air nozzle speed was varied by changing the pulverizer inlet air volume. Due to limitations in the pulverizing system, the primary air speed was difficult to vary widely, resulting in little change in boiler thermal efficiency. This indicates that small changes in the primary air speed have little impact on boiler thermal efficiency. 6. Pulverized Coal Fineness
Reducing pulverized coal fineness reduces the combustible content of fly ash and slag, improving boiler thermal efficiency.
7. Grinding Method
Combining the operation of separate pulverizers results in minimal differences in boiler thermal efficiency, but significantly impacts steam temperature.