Based on heat and mass transfer characteristics of spontaneous combustion of coal,Arrhenius equation and the Ranz-Marshall correlation,a novel approach was proposed in this paper to estimate oxygen consumption rate of...Based on heat and mass transfer characteristics of spontaneous combustion of coal,Arrhenius equation and the Ranz-Marshall correlation,a novel approach was proposed in this paper to estimate oxygen consumption rate of self-ignition of coal at high temperature.Compared with the conventional methods,this approach involves not only kinetic properties of self-ignition of coal and temperature,but also the ambient air flow characteristics and diameter of coal particle.To testify the proposed approach,oxygen consumption rates at high temperature were measured by the programmable isothermal oven experiments.Comparisons between experimental and theoretical results indicate that the rates of oxygen depletion calculated by the proposed approach agree well with those measured from laboratory-scale experiments,which further validates the proposed approach.展开更多
稠油富氧火驱是一种增强型火烧油层技术,通过注入高浓度氧气能有效提高稠油燃烧效率,但关于稠油富氧燃烧机理及不同含氧量下的动力学参数研究较少。为明确富氧对稠油火驱氧化特性的影响,以辽河稠油为例,利用同步热分析仪研究了不同氧气...稠油富氧火驱是一种增强型火烧油层技术,通过注入高浓度氧气能有效提高稠油燃烧效率,但关于稠油富氧燃烧机理及不同含氧量下的动力学参数研究较少。为明确富氧对稠油火驱氧化特性的影响,以辽河稠油为例,利用同步热分析仪研究了不同氧气浓度和升温速率条件下的稠油氧化热失重以及放热等特性变化,基于等转化率法计算不同转化率、不同氧气浓度下的活化能,进而利用数值模拟研究了富氧对火驱的改善效果。结果表明,富氧环境下稠油氧化仍可划分为低温氧化前、低温氧化、焦炭沉积和高温氧化4个阶段。随着氧气加量由20%增至100%,氧化反应更加强烈,反应速率更大,放热量升高,对应的焦炭沉积阶段提前20℃。不同氧气加量下活化能的变化趋势相同,在低温氧化阶段氧气浓度对活化能的影响较小,但高温氧化阶段响应剧烈,活化能降低15~25 k J/mol。在相同氧气浓度下,升温速率增加会导致热滞后现象。数值模拟研究验证了富氧条件可有效提高火驱燃烧效果。当氧气加量由30%增至50%时,累积产油量增幅为11234 m^(3);氧气加量由70%增至100%时,累积产油量增幅(3753 m^(3))较小,推荐采用50%~70%的氧气作为富氧火驱注入气。随着氧气浓度的增加,前缘温度(350~450℃)增加,提高了燃烧的稳定性,改善了常规火驱燃烧效果。展开更多
基金Project(51534008) supported by the National Natural Science Foundation of China
文摘Based on heat and mass transfer characteristics of spontaneous combustion of coal,Arrhenius equation and the Ranz-Marshall correlation,a novel approach was proposed in this paper to estimate oxygen consumption rate of self-ignition of coal at high temperature.Compared with the conventional methods,this approach involves not only kinetic properties of self-ignition of coal and temperature,but also the ambient air flow characteristics and diameter of coal particle.To testify the proposed approach,oxygen consumption rates at high temperature were measured by the programmable isothermal oven experiments.Comparisons between experimental and theoretical results indicate that the rates of oxygen depletion calculated by the proposed approach agree well with those measured from laboratory-scale experiments,which further validates the proposed approach.
文摘稠油富氧火驱是一种增强型火烧油层技术,通过注入高浓度氧气能有效提高稠油燃烧效率,但关于稠油富氧燃烧机理及不同含氧量下的动力学参数研究较少。为明确富氧对稠油火驱氧化特性的影响,以辽河稠油为例,利用同步热分析仪研究了不同氧气浓度和升温速率条件下的稠油氧化热失重以及放热等特性变化,基于等转化率法计算不同转化率、不同氧气浓度下的活化能,进而利用数值模拟研究了富氧对火驱的改善效果。结果表明,富氧环境下稠油氧化仍可划分为低温氧化前、低温氧化、焦炭沉积和高温氧化4个阶段。随着氧气加量由20%增至100%,氧化反应更加强烈,反应速率更大,放热量升高,对应的焦炭沉积阶段提前20℃。不同氧气加量下活化能的变化趋势相同,在低温氧化阶段氧气浓度对活化能的影响较小,但高温氧化阶段响应剧烈,活化能降低15~25 k J/mol。在相同氧气浓度下,升温速率增加会导致热滞后现象。数值模拟研究验证了富氧条件可有效提高火驱燃烧效果。当氧气加量由30%增至50%时,累积产油量增幅为11234 m^(3);氧气加量由70%增至100%时,累积产油量增幅(3753 m^(3))较小,推荐采用50%~70%的氧气作为富氧火驱注入气。随着氧气浓度的增加,前缘温度(350~450℃)增加,提高了燃烧的稳定性,改善了常规火驱燃烧效果。
