Technical Problems Occurring in Ultra-low Load Operation of Pulverized Coal-fired Boilers and the Solutions

An analysis was conducted on the technical problems occurring in low load (below 40% rated load) and ultra-low load (20%-30% rated load) operation of current domestic pulverized coal-fired boilers, such as poor combustion stability, low hydrodynamic safety, high pollutant emission and low unit economy, etc., following which, corresponding countermeasures were discussed. Results show that the boiler could achieve steady combustion under ultra-low load condition after taking corresponding countermeasures such as refined combustion adjustment, etc. The hydrodynamic safety of a once-through boiler is relatively high in the process above 30% rated load; with the reduction of unit load, the hydrodynamic safety of a drum boiler increases, while its economic performance drops significantly. As to the pollutant emission, more attention should be paid on the NO_x concentration.