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The high-efficiency and low-nitrogen combustion technology of pulverized coal is a hot topic of continuous attention in the field of efficient utilization of coal. As the core equipment of pulverized coal boilers, it is important to study the design principles and technologies of pulverized coal burners suitable for multi-coal types and wide load conditions. The reverse injection flow stabilized gas mechanism is mostly used in the field of aero engines and gas turbines, and is rarely used in the field of pulverized coal combustion.
The influence of the pre-combustion chamber on the flow field characteristics of the swirl burner has been studied extensively, but the relevant research on the effect of the pre-combustion chamber on the flow field of the reverse spray cyclone burner and the stable combustion mechanism of the pre-combustion chamber of the reverse jet flow pulverized coal burner have rarely been seen.
In order to further broaden the adaptability of coal species and optimize the pre-combustion chamber reverse spray cyclone burner, the cold state test methods such as the streamer method and the hot film hotline anemometer are used to study the influence of the pre-combustion chamber on the flow field of the pulverized coal burner under the reverse jet and swirl conditions.
The boundary of the reflux zone, the axial velocity distribution, the turbulence intensity and the relative reflux rate are the core indicators for evaluating the performance of the burner. Measuring and analyzing the pre-combustion chamber is of great significance for the boundary of the reflux zone of the reverse spray swirl pulverized coal burner, the axial velocity distribution, the turbulence intensity and the relative reflux rate.
The backflow zone boundary
Axial dimensionless average velocity
Turbulence distribution
Relative reflux rate distribution
The results show that:
1) The pre-combustion chamber does not change the shape of the ring of the backflow zone of the back-injection swirl pulverized coal burner, and the impact of the pre-combustion chamber on the X/DX/DX/D>2.3 area is negligible. Under the action of the pre-combustion chamber, the diameter at the widest part of the reflux zone is reduced from 0.97D to 0.86D, the maximum relative reflux rate position is moved from section X/D=1 to section X/D=1.6, and the relative reflux rate is reduced from 1.17 to 0.99.
2) The pre-combustion chamber has a great influence on the distribution of axial average velocity and turbulence in the secondary wind area. Without the pre-combustion chamber, the peak disappears in the X/DX/D>1.6 area, and the internal and external secondary winds are completely mixed; under the pre-combustion chamber conditions, in the X/DX/D > 1.6 area, the speed and turbulence are evenly distributed along the radial direction.
3) Due to the role of the pre-combustion chamber, the reflux area of the back-injection swirl pulverized coal burner has the characteristics of low axial speed and large turbulence, which is conducive to the stable combustion of pulverized coal in actual operation; and the air flow velocity of the wall surface of the pre-combustion chamber is large and rigid, so as to avoid the over-temperature or coking phenomenon of the wall surface of the pre-combustion chamber.
Citation format
NIU Fang. Study on the Effect of Pre-combustion Chamber on Flow Field Characteristics of Reverse Spray Swirl Pulverized Coal Burner[J].Clean Coal Technology,2020,26(2):73-77.
NIU Fang.Influence of pre combustion chamber on flow characteristics of reverse swirl pulverized coal burner[J]. Clean Coal Technology，2020,26(2):73-77.
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