沉降炉中生物质热解产物的脱硝特性

NO Reduction Characteristics of Biomass Pyrolysis Products in a Drop-tube Reactor

利用连续沉降炉模拟白酒糟循环流化床解耦燃烧再燃区的反应气氛,研究各因素对半焦、焦油和热解气脱硝效率(比脱硝效率)的影响.结果表明,反应温度由800℃升至1050℃,热解产物比脱硝效率均增大;半焦和焦油达到最佳比脱硝效率所需的停留时间为3.4s;随反应气中NO浓度由400×10-6(φ)增加到1000×10-6(φ),热解产物比脱硝效率均呈降低趋势,但NO绝对还原量却呈增加趋势;随反应气中O2浓度增加,半焦比脱硝效率增大,热解气比脱硝效率降低,焦油比脱硝效率呈先增加后减少的趋势,在O2浓度为1.6%(φ)时达最大,为60.1%.在本研究的反应条件下,焦油比脱硝效率最好,热解气次之,半焦效果较差.

A continuous drop-tube furnace was used to simulate the combustion conditions in the reburning zone of circulating fluidized bed decoupling combustion, and a series of experiments was conducted to study the NO reduction characteristics of pyrolysis products of distilled spirit lees, char, tar and pyrolysis gas, in terms of the specific NO reduction efficiency （r/E） defined against the unit-mass flow reductant. The results indicated that with increasing of reaction temperature from 800 to 1050 ℃, r/E of char, tar and pyrolysis gas increased. The optimal residence time for the possibly highest r/E was 3.4 s for tar and char reductants. With increasing of NO concentration from 400×10^-6（φ） to 1000×10^-6（φ） in the reactant gas, the specific NO reduction efficiency decreased, but the reduced absolute NO amount increased for all the pyrolysis products. Increasing the 02 concentration in the reactant gas caused r/E to decrease for char, to increase for pyrolysis gas and a parabola variation with increase first and then decrease for tar. At the 02 concentration of 1.63%（φ）, r/E for tar was highest and reached 60.1%. This study demonstrated that unit-mass flow reactant tar enabled the highest NO reduction in comparison with char and pyrolysis gas.