摘要
在煤炭开采过程中,低浓度瓦斯涌出后一般直接排放至大气中,造成了严重的资源浪费和环境污染。为了提高极低浓度瓦斯的利用率,以极低浓度的甲烷(体积分数小于5%)作为模拟气体,向其中掺混易燃易爆的二甲醚气体促进其燃烧,借助CHEMKIN模拟软件,对掺混气体燃烧过程进行模拟分析,研究了不同当量比对混合气体燃烧后压力及生成物的影响。结果表明,二甲醚能够促进极低浓度甲烷燃烧,且燃烧后最大压力随当量比增加逐渐增大并趋于稳定。同时,当量比对于掺混燃烧气体产物成分的影响较大,在甲烷初始体积分数相同的条件下,掺混燃烧产生的尾气中CO体积分数随当量比(Φ)增加而增加,当Φ<0.8时,燃烧产物主要是CO2,当Φ>0.8时,燃烧产物主要是CO;CO2体积分数随当量比增大先增大后减小,存在峰值点,初始甲烷体积分数越大,CO2体积分数峰值越小。在当量比小于1.2时,燃烧产物中剩余甲烷体积分数很小;在当量比大于1.2时,燃烧产物中剩余甲烷体积分数随当量比增加而迅速增加。在当量比相同时,甲烷的转化率随初始甲烷体积分数增加而增加。
The present paper is aimed to improve the utilization ratio of the ultra-low concentration methane.As is known,when methane(at the concentrated rate less than 5%) has been taken as a simulated gas,its combustion can be promoted by way of mixing the flammable and even explosive gas dimethyl ether into it in the process of coal mining.What is more,as the ultra-low concentration methane can usually be discharged directly into the atmosphere when gushed out,it may become a serious waste resource and harmful environmental pollutant.It is just for the said reason that we have traced and determined the impacts of its equivalence ratio on the combustion pressure with its resultant being examined by using a numerical simulation software known as CHEMKIN.The results of our examination indicate that,the said dimethyl ether is in a position to promote ultra-low concentration methane combustion,whose maximum pressure tends to increase gradually with the increase of the equivalent ratio.And,then,it tends to decrease gradually when it reaches its maximum rate near the stoichiometric ratio.At the same time,its equivalent ratio can potentially have a serious influence on the gas product composition of the mixed combustion.And,in such a juncture,in case the initial methane concentration keeps at the same level,the main component of the combustion products should be turned into carbon dioxide when the equivalence ratio stays at less than 0.8.However,when the main component of the combustion products changes into carbon monoxide till the equivalence ratio becomes greater than 0.8,it will then gradually increase with the increase of the equivalence ratio.In the mean time,the residual methane gas in the combustion products may remain still much small in amount before the equivalence ratio tends to decrease to less than1.2.Just in such a critical case,the amount of the residual methane gas in the combustion products may increase fast with the increase of the equivalence ratio if the equivalence ratio turns out to be greater than 1.2.Therefore,when the equivalence ratio comes to the same level,the conversion rate of methane would increase with the increase of the methane concentration.The above said results we have gained can therefore be able to provide a theoretical basis to promote the combustion and utilization of the ultra-low concentrated methane.
作者
聂百胜
盖波青
宫婕
李刚
司荣军
NIE Bai-sheng;GE Bo-qing;GONG Jie;LI Gang;SI Rong-jun(School of Resource and Safety Engineering,China University of Mining & Technology (Beijing),Beijing 100083,China;School of Resources and Civil Engineering,Northeastern University,Shenyang 110004,China;China Coal Technology Engineering Group Chongqing Research Institute,Chongqing 400639, China)
出处
《安全与环境学报》
CAS
CSCD
北大核心
2018年第6期2420-2422,共3页
Journal of Safety and Environment
基金
中央高校基本科研业务费项目(2009KZ03)
华北科技学院河北省矿井灾害防治重点实验室开放基金项目(KJZH2017K01)
国际清洁能源拔尖创新人才项目(201802180049)
关键词
环境工程学
极低浓度甲烷
二甲醚
掺混燃烧
数值模拟
environmental engineering
ultra-low concentration methane
dimethyl ether
mixing combustion
numerical simulation
