低温干馏煤气/富氧大当量比燃烧热力学分析  

Thermodynamic Analysis on Oxy-fuel Combustion of Low-temperature Coal Pyrolysis Gas in Fuel-rich Condition

作　　者：任萌萌 赵俊学[1] 邹冲[1] 何江永 张红 REN Mengmeng;ZHAO Junxue;ZOU Chong;HE Jiangyong;ZHANG Hong(School of Metallurgical Engineering, Xi’an University of Architecture and Technology, 710055 Xi’an, China)

机构地区：[1]西安建筑科技大学冶金工程学院,西安710055

出　　处：《煤炭转化》2021年第4期13-19,共7页Coal Conversion

基　　金：陕西省自然科学基础研究计划项目(2021JQ-505);陕西省重点研发计划项目(2020GY-229);西安建筑科技大学人才科技基金资助项目(RC1910).

摘　　要：为明确煤气/富氧大当量比燃烧过程中煤气各可燃组分间氧化剂竞争机制及其对内热火焰温度和干馏介质成分的影响,对该反应体系进行了热力学分析。结果表明:各组分的燃烧优先度随反应温度而变化,低温(<849 K)下CO优先燃烧,高温(>1143 K)下CH_(4)优先燃烧;除选择性燃烧外,甲烷化和甲烷重整反应在800 K~1000 K发生转变、水煤气反应平衡等因素共同决定了反应体系平衡组分中的xCH_(4)随温度升高而降低,xCO和xH_(2)随温度升高而升高且CO和H_(2)相互共存;各燃料组分的选择性燃烧及不完全燃烧产物间相互转化的热效应,导致绝热火焰温度差值高达550 K以上;CO_(2)稀释对平衡温度的降低作用大于H_(2)O稀释对平衡温度的降低作用,但H_(2)O稀释条件下平衡组分中的xH_(2)更高;当量比大于6时,当量比对平衡温度的影响减弱。实际工艺参数设计中可以适当降低当量比以提高干馏介质中的氢气含量,有助于加氢热解。To illustrate the competitive combustion mechanism among different components in the pyrolysis gas under fuel-rich conditions and clarify the effects on the inner heating flame temperature and composition of the pyrolysis medium,the thermodynamic analysis on the corresponding reaction system is conducted.It is indicated that the combustion priority of different fuel components alters with the reaction temperature.At the temperature lower than 849 K,CO combusts preferentially,while at the temperature higher than 1143 K,CH_(4)combusts preferentially.In addition to the selective combustion,the inverse of the methanation reactions to the methane reforming reactions at the temperature around 800 K-1000 K,and the equilibrium of the water-gas shift reaction,jointly determine the species distribution that the CH_(4)mole fraction decreases with rising temperature while CO and H_(2) mole fraction increase with rising temperature and coexist for a long term.The selective combustion and the thermal effect of the conversion among the partial oxidized products lead to the adiabatic flame temperature higher than 550 K.The decrease effect of the CO2 dilution on the equilibrium temperature is stronger than that of the H_(2)O dilution,while the H_(2)O dilution results in the higher H_(2)mole fraction in the equilibrium composition.When the equivalence ratio becomes larger than 6,the effect of the ratio on the equilibrium temperature is insignificant.Decreasing the equivalence ratio moderately in practice can improve the H_(2)mole fraction in the pyrolysis medium,which may favor the hydropyrolysis.

关 键 词：低温煤干馏 热力学分析 选择性燃烧 大当量比 富氧燃烧 

分 类 号：TQ536.9[化学工程—煤化学工程] TK16[动力工程及工程热物理—热能工程]