水蒸气对脱灰煤焦O_(2)/H_(2)O燃烧特性的影响

Effect of steam on O_(2)/H_(2)O combustion characteristics of demineralized coal char

为实现“30·60”碳中和的目标,先进的燃烧技术如Oxy-steam燃烧能有效减少燃煤CO_(2)排放。基于新一代Oxy-steam燃烧技术提出的煤基固体燃料-氧-水蒸气燃烧近零排放发电系统(OCCSS)是能实现燃煤CO_(2)近零排放的发电方式之一。使用脱灰煤作为燃料能省去除尘装置,同时降低煤中灰分对设备的损害。研究脱灰煤在O_(2)/H_(2)O条件下的燃烧特性,能为后续的燃烧室设计提供理论依据。采用三步酸洗法(HCL-HF-HCL)制取准东脱灰煤,使用高温管式炉在900℃制备常压焦炭,在微型流化床O_(2)/H_(2)O燃烧实验系统进行温度为950℃、O_(2)体积分数分别为5%,15%,21%,30%、H_(2)O体积分数为10%,25%,40%,60%的快速升温O_(2)/H_(2)O燃烧实验。研究不同O_(2)体积分数条件下,H_(2)O(g)对脱灰煤焦的O_(2)/H_(2)O燃烧特性的影响,探究其对燃烧进程的促进/抑制规律。在单颗粒快速升温O_(2)/H_(2)O燃烧条件下(950℃),O_(2)体积分数为5%~30%时,H_(2)O(g)对脱灰煤的燃烧过程均表现出抑制作用。O_(2)体积分数小于21%时,H_(2)O(g)体积分数变化对焦炭燃烧的抑制作用尤为明显。H_(2)O(g)体积分数从0增至60%时,低O_(2)体积分数(5%,15%)条件下焦炭的转化时间分别为34.67,23.22 s,是体积分数为21%时转化时间的1.81和1.21倍。在不同H_(2)O(g)体积分数区间,O_(2)体积分数对焦炭转化的促进效果会改变。O_(2)体积分数小于15%时,其体积分数的增加能明显促进焦炭转化;O_(2)体积分数大于15%时,其作用效果与H_(2)O(g)体积分数有关,当H_(2)O(g)体积分数不大于25%,O_(2)体积分数的增加对焦炭转化无明显的提升作用。

In order to achieve the goal of“30·60”carbon neutrality,the advanced combustion technologies such as Oxy-steam combustion can effectively reduce coal fired CO_(2)emissions.For the new generation of Oxy-Steam combustion technology,Oxy-Coal Combustion Steam System for power generation with near-zero emissions(OCCSS)can achieve near-zero emissions of coal-fired CO_(2).Using demineralized coal as a fuel can save dust removal equipment,and reduce the damage of the ash in the coal to the equipment.Research on the characteristics about the demineralized coal which is used for its combustion under O_(2)/H_(2)O conditions can provide a theoretical basis for subsequent combustion chamber design.A three step pickling method(HCL-HF-HCL)is used to prepare Zhundong demineralized coal.A high temperature tube furnace is used to prepare char at 900℃.The rapid heating O_(2)/H_(2)O combustion experiment at 950℃,5%,15%,21%,30%O_(2)and 15%,25%,40%,60%H_(2)O(g)was performed by a micro fluidized bed O_(2)/H_(2)O combustion experiment system.Study the effect of H_(2)O(g)on the O_(2)/H_(2)O combustion characteristics of demineralized coal char under different O_(2)concentration,and explore its promotion/inhibition law on the combustion process.Under the condition of O_(2)/H_(2)O combustion with rapid temperature rise of single particle(950℃),when the O_(2)concentration range is 5%-30%,H_(2)O(g)has an inhibitory effect on the combustion process of demineralized coal.When the O_(2)concentration is less than 21%,the H_(2)O(g)concentration change has a particularly obvious inhibitory effect on char combustion.When the H_(2)O(g)concentration changes from 0 to 60%,the conversion time of char under low O_(2)concentration conditions(O_(2)concentration:5%,15%)is 34.67 s and 23.22 s,which are 1.81 and 1.21 times of the 21%O_(2)conversion time.In different H_(2)O(g)concentration intervals,the promotion effect of O_(2)concentration on char conversion will be changed.When the O_(2)concentration is less than 15%,the increase in its concentration can significantly promote the conversion of char.When the concentration of O_(2)is greater than 15%,its effect is related to the concentration of H_(2)O(g).When the concentration of H_(2)O(g)is below 25%,the increase in O_(2)concentration does not significantly improve the conversion of char.