生物质炭再燃脱硝特性的试验研究

Experimental Study on NO Reduction by Biomass Char Reburning

以木片炭和木屑混合物(WCC)、稻秆(RS)、桑树枝炭(MBC)和竹炭(BMC)为原料,利用携带流再燃脱硝试验装置,在NO初始体积分数为1×10-4～3×10-4条件下,研究了生物质炭再燃脱硝特性,分析了再燃燃料种类、再燃燃料粒径、再燃区反应温度t2、停留时间τ等因素对再燃脱硝效率的影响.结果表明:对于4种试验用生物质,WCC再燃脱硝效果最好,其脱硝效率为63.4%,RS和BMC次之,MBC没有脱硝效果;随着再燃燃料粒径的减小,再燃脱硝效果趋好;随着NO初始体积分数的减小,再燃脱硝效率降低,当NO初始体积分数低于1×10-4时,RS再燃脱硝效率反而升高;当t2=950～1 250℃时,WCC再燃脱硝效率随再燃区温度的升高而提高;在τ=0.4～0.8s时,随着τ的缩短,生物质再燃脱硝效率下降,当τ=0.4s时,再燃脱硝效率小于10%.为了保证一定的再燃脱硝效率,建议WCC再燃区反应温度和停留时间分别保持在1 150℃和0.8s.

Nitric oxide （NO） removal characteristics were studied in an entrained flow reactor at an initial NO volume fraction of 1 X 10^- 4-3 ）〈 10-4 by reburning various kinds of biomass, such as the mixture of wood chips char and sawdust （WCC）, rice straw （RS）, mulberry branch char （MBC） and bamboo char （BMC）, etc. , during which the influence of following factors on the NO removal was analyzed, like the category and particle size of reburning fuel, reaction temperature （t2） and lingering time （r） in the reburn ing zone, and so on. Results indicat that among all the four kinds of biomass tested, the strongest reduc tion effect can be obtained by reburning WCC with a highest NO removal efficiency of 63.4%, followed by RS and BMC, and MBC has nearly no effect on NO reduction; the smaller the particle size, the higher the NO removal efficiency; NO removal efficiency decreases with reducing initial NO volume fraction, how ever, when the initial NO volume fraction drops below 1 X 10^- 4 the removal efficiency by RS rises in stead; NO removal efficiency increases with rising temperature in reburning zone within the range of t2= 950-1 250℃, which reduces with shortening r in the range of r=0.4 0.8 s, and at r=0.4 s, the efficiencywill be less than 10%. To guarantee a reasonable NO removal efficiency, it is recommended that the reac tion temperature and lingering time in the reburing zone of WCC be set at 1 150 ℃ and 0.8 s, respectively.