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在我国电站锅炉向高参数大容量发展的过程中,锅炉的一次风管数目,从以前的4根发展到目前1000t/h锅炉的32根,与一次风管相应的排粉机台数也增加到4台。由于排粉机台数的增加,使一次风管长短的差别增大,尤其排粉机出口气流分布不均,再加上流速高的管子布置于最短距离造成不均匀系数迭加,形成了一次风管间流速的严重不均现象,结果流速低的管子常发生堵管、自燃、喷嘴结焦烧坏;流速高的一次风冲刷水冷壁。此外一次风各管间流速不均,使切圆中心偏移,局部水冷壁过热爆管;烟气出口温差大导致过热器局部过热爆管;炉内燃烧恶化,燃尽度下降等。为均衡各管之间的流速,谏壁电厂首次在1000t/h直流炉四台排粉机出口的32根一次风管上均安装了圆型可调缩孔,一次风速的不均匀系数乙排从装前的0.75下降到0.22。但圆型缩孔阻力大,关一根一次风管上的圆型缩孔阻力增加30～40mm水柱,8根一次风管全关时,排粉机出口总风压高达510mm水柱。在调试阶段防爆门经常动作,为此在甲号排粉机上改装了月牙型可调缩孔,其一次风不均匀系数从0.49下降到0.13,阻力系数从圆型的6.09下降到0.6。达到了调节范围广,阻力小的要求。
In the process of high-capacity large-capacity boiler development in China, the number of primary air ducts in boilers has increased from 4 to 32 in the current 1000t / h boilers. The number of air purifiers corresponding to primary ducts has also increased to 4 sets. Due to the increase of the number of ejectors, the difference of the length of the primary air duct is increased. In particular, the air flow at the exit of the ejector is unevenly distributed, and the pipe with the high speed is arranged at the shortest distance to cause the uneven coefficient to be superimposed to form a primary air Pipeline between the serious uneven flow rate, the result of low flow tube often plugged, spontaneous combustion, nozzle coke burnout; a high velocity of the water scouring water wall. In addition, an uneven flow velocity between the tubes of each wind causes the center of the tangent circle to shift and the local water wall overheats the squib. The large temperature difference of the flue gas outlet leads to the local overheating squib of the superheater. The combustion in the furnace is deteriorated and the degree of burn down is reduced. In order to balance the flow rate between the various tubes, Jianbi Power Plant installed circular adjustable shrinkage cavities for the first time on 32 primary ducts of the four discharge machines of the 1,000t / h DC furnace. The uneven coefficient of the first wind speed, From pre-loaded 0.75 down to 0.22. However, the shrinkage of circular shrinkage is large, and the resistance of the circular shrinkage cavity on the primary air duct is increased by 30 to 40 mm. When the primary air duct is closed completely, the total air pressure at the outlet of the powder discharger is up to 510 mm water column. Explosion-proof doors in the commissioning phase of the regular action, for this reason in the modified version of the c-row crescent-type adjustable shrinkage cavity, the primary wind non-uniform coefficient decreased from 0.49 to 0.13, drag coefficient decreased from 6.09 to 6.0. Has reached a wide range of regulation, resistance requirements.