Narrow Results

The characteristics of the flow, the combustion field and NOx emissions in the coal-fired boiler are numerically investigated under different burner layer combination modes for a 660 MW swirling opposed coal-fired utility boiler. The simulation results are relatively close to the actual measured results, with relative errors of less than 10%. The results demonstrate that at the rated load of 5 mills in service, the differences in NOx emissions and carbon contents in fly ash is small in cases of the same-layer burner operating in the front wall and in the rear wall. Stopping upper layer burners enhances air classification and increases the residual time of pulverized coal particles, as compared to stopping the middle layer burners; consequently, the NOx emission and carbon content in the fly ash are reduced by relative values of 9.5% and 9.8%, respectively. In addition, stopping upper layer burners reduces NOx emission and improves combustion efficiency in actual operational conditions.

Through the investigation on flame-retardant properties of three kinds of inner-spring mattresses, it is found that without flame retardant, the heat release rate (HRR) of spring mattress is up to 600 kW, the concentration of carbon monoxide (CO) and carbon dioxide (CO₂) is 0.08% and 1.5% respectively. Thus, mattress has a very high fire risk. It could cause injuries and deaths through spreading of fire and emitted gases. The mattress with only fabric treated with flame retardant could be ignited, but did not cause the flame spread across a large area, the flame retardant performance satisfied grade B1 in GB 8624-2012. For the mattress which has both fabric and filler being flame retardant, the flame extinguished soon after the ignition sources were removed. Therefore, flame retardant performance for the last mattress was very well.