Experimental Study On Cold-Model Aerodynamic Characteristics Of A Tangentially Oil/Gas-fired Boiler

In this work, experimental study of aerodynamic filed was conducted on a cold-model with scaled ratio of1:15to a630MW Tangentially Oil/Gas-Fired Boiler. Based on wind speed measurement of the furnace cross section and fireworks trace method, the variants of the aerodynamic field caused by different design patterns were analyzed:varying supposed tangential circle diameter, different space between up and down grouped burners, octagonal OFA and diagonal different tangential circles. The results in this study can provide useful information for the design of combustion system for large scale oil and gas boilers.Test results show that the main burners of oil furnace have some specific properties. By separating them into up and down two groups and increasing the distance between them, it can effectively reduce the air tangential circle diameter in the furnace, and reduce the possibility of high temperature corrosion and air flow scouring water wall caused by excessive tangential circle diameter. But the lower group burner can not be too low, as it can increase the possibility of air washing against the bottom of the furnace water wall. From this study, it can be found that the smaller the imaginary tangential circle diameter, the smaller the actual tangential circle in the furnace would be resulted. But due to its strong rigidity and good air supply for the octagonal OFA jet, it has the maximum designed tangential diameter and the minimum magnified ratio. Due to the influence of OFA, the tangential diameters of the burner area along the furnace upward first increases and then decreases, and attains the maximum value at the8th layer of the nine layers burners. Octagonal OFA can stabilize the airflow and uniform the vertical airflow among the front, back, left and right sides at the furnace exit, which can reduce the effect of smoke gas velocity deviation on heat transfer of horizontal layout of the superheaters.The measurement of the wind speed attached to the front wall showed that it decreased from the central axis to the both sides. The attached wind speed in the lower combustor areas was apparently higher than that in the upper combustor areas and areas above the OFA. And the maximum wind speed point was located10cm off the right side of the front wall central axis and at the height of the third layer of burners. At this point, the wind speed was7.86m/s when the main injection jet speed was approximately24.5m/s. Thus to avoid the erosion, high temperature corrosion and overheating of water wall tubes, appropriate measurements can be taken such as enhance the anticorrosion coating of the corresponding section of the real furnace or utilize the tubes of better materials. At the same time, more attention should be paid to the temperature monitoring of the water wall in this region during industrial operation.