摘要
针对低甲烷浓度煤层气的特点,设计了150kW部分预混式旋流燃烧器,实验研究了燃烧器结构对低甲烷浓度煤层气燃烧的影响,考察了低甲烷浓度煤层气在燃烧器内的速度分布特性、旋流强度及甲烷浓度变化对温度分布的影响规律。结果表明：加装钝体结构的旋流燃烧器在燃用甲烷体积分数为20%的煤层气时,火焰长度降低,射流刚性增强,燃烧高效稳定;Z轴的逆轴向速度梯度范围随着直旋配风比的增加逐渐增大,射流刚性提高,中心回流区域变大;R轴的逆轴向速度梯度范围随着距离燃烧器喷口距离的增加逐渐缩小,回流区域变小,卷吸高温烟气的能力下降,不利于高效稳定燃烧;燃烧器喷口中心处的旋流强度随热负荷的增加而逐渐增大;当热负荷增加到50%以后,旋流强度随过量空气系数的增大而小幅度波动;当煤层气中甲烷体积分数为20%~30%时,随着甲烷浓度的增加,燃烧器出口的火焰形状呈现出变短变窄的趋势,燃烧稳定性提高,出口温度不超过1 000K,可以有效避免喷口被烧坏。
According to the unique properties of low-concentration coal-bed methane（CBM）,we designed a 150 kW swirled partially premixed burner.An experimental study was conducted to investigate the effects of the burner structure on the low-concentration CBM combustion,and the controlling rules of velocity distribution,swirl intensity and methane concentration on temperature distribution during the combustion in the partial-premixed swirling burner.The following results were achieved.（1）This swirled partially premixed burner equipped with bluff bodies is proved to be favorable for burning the CBM with 20% methane in volumetric concentration,with the performances of shorter flame length,stronger jet stiffness,high combustion efficiency,and stable burning.（2）With the increase of the primary/secondary air ratio,the scope of reverse axial velocity gradient along Z-axis gets wider,and not only can a better jet flow rigidity be obtained,but the center reflux area gradually becomes larger.（3）With the increase of the distance between the section and the nozzle outlet,the scope of reverse axial velocity gradient along R-axis gets narrower,the width of recirculation zone becomes smaller and the capability of high-temperature flue gas entrainment goes down,which is not conducive to maintaining the reactor in a high-efficiency and steady state.（4）With the thermal load increasing,the swirl intensity significantly augments,but the excessive air coefficient has little influence on the swirl intensity after the thermal load increases to 50%.With the rising of the methane volumetric concentration ranging from 20%-30%,the flame shape of the burner outlet becomes shorter and narrower,and the combustion stability is improved;the temperature around the burner outlet is below 1000 K,and the risk of the burner nozzle burned out will be mitigated.
出处
《天然气工业》
EI
CAS
CSCD
北大核心
2014年第11期115-121,共7页
Natural Gas Industry
基金
国家自然科学基金(编号:51206200)
中央高校基本科研业务经费专项资金项目(编号:CDJZR12140031)
关键词
低甲烷浓度煤层气
部分预混式旋流燃烧器
钝体
回流区
燃烧器
燃烧特性
low-concentration coal-bed methane
swirled partially premixed burner
bluff body
recirculation zone
burner
combustion characteristics
