再燃过程影响因素及燃尽特性研究

Study of the Influencing Factors and Burn-out Characteristics of a Reburning Process

以包含两种低挥发分贫煤在内的5种煤作为主燃料,在一台36kW一维炉上对气体燃料再燃过程及其燃料燃尽特性进行了详细实验研究。实验表明,相同条件下,挥发分含量越高的煤作为主燃料时气体燃料再燃过程的脱硝效率能够达到越大,当低挥发分煤种作为主燃料时,必须采用更大气体再燃燃料比例和更长再燃区停留时间才能获得高挥发分煤种作为主燃料时相同的再燃脱硝效率。实验结果表明,即使采用低挥发分煤作为主燃料,当气体再燃燃料比例达到10%～15%,再燃区停留时间达到0.7～0.9s,再燃区过量空气系数在0.8～0.9时,气体燃料再燃过程就能在保证煤粉颗粒燃尽率不显著降低,同时气体再燃燃料充分燃尽的前提下,获得50%以上的再燃脱硝效率。

With five kinds of coal,including two types of low volatile lean coal,serving as the main fuel,a detailed experimental study was conducted of the reburning process and fuel burn-out characteristics of gaseous fuels on a 36 kW one-dimensional boiler.The test results show that under same conditions,the higher the volatile content of the coal which serves as the main fuel,the greater the denitrification efficiency of the gaseous fuel in the reburning process.When a coal of low volatile content serves as the main fuel,a bigger proportion of gaseous reburning fuel and a long residence time in the reburning zone will be required to attain the same reburning denitrification efficiency as that of a coal with a high volatile content.The test results indicate that even if a low-volatile coal was used as a main fuel,when the gaseous reburning fuel proportion is 10% to 15%,the residence time in the reburning zone reaches 0.7 s to 0.9 s and the excess air factor in the reburning zone is between 0.8 and 0.9,the gaseous fuel reburning process can ensure that the burn-out rate of pulverized-coal particles will not drop significantly.In the meanwhile,under the precondition of the gaseous fuel being sufficiently burned up,a reburning denitrification efficiency of above 50% can be obtained.