空气旋流强度对低热值煤层气扩散燃烧特性影响的数值模拟研究  

Numerical Study on the Influence of Inlet Air Swirl Intensity on Diffusion Combustion Characteristics of Low Calorific Value Coalbed Methane

作　　者：周宇 张琦琦 熊亚鑫 Zhou Yu;Zhang Qiqi;Xiong Yaxin(School of Physics and Electrical Engineering,Liupanshui Normal University,Liupanshui,553004,China)

机构地区：[1]六盘水师范学院物理与电气工程学院,贵州六盘水553004

出　　处：《六盘水师范学院学报》2024年第3期1-10,共10页Journal of Liupanshui Normal University

基　　金：贵州省科技厅科学技术基金“低热值煤层气掺混二甲醚扩散燃烧特性及其互换性研究”(黔科合基础-ZK〔2021〕一般280);六盘水师范学院一流本科专业建设点项目“能源与动力工程一流本科专业建设”(LPSSYylzy2008);六盘水市红果开发区龙鼎工贸有限公司横向项目“新型钙钛矿复合氧化物的建构及其低浓度瓦斯催化燃烧性能研究”(LD-LPSSY-ZY-2021-01)。

摘　　要：我国煤层气资源丰富,居世界第三位,但利用率低,且利用形式单一,尤其是井下抽取的低热值煤层气,因甲烷浓度只有10%-30%,目前主要采取排空的方式,造成能源浪费和环境问题。通过组织燃料或氧化剂以旋流方式进入燃烧器形成射流,采用旋流燃烧的方式优化燃烧工况的旋流燃烧技术,可以有效提升燃烧强度,显著提高火焰的稳定性。实践证明,旋流燃烧技术非常适用于低热值气体燃料的燃烧。通过计算流体力学的方法,建立低热值煤层气旋流燃烧模型,在与相关文献数据对比验证的基础上,分别从旋流流场、火焰温度、辐射换热等方面,对空气入射旋流强度与低热值煤层气扩散燃烧特性之间的关系进行了数值模拟研究。结果表明:旋流数从0提高到0.6时,炉膛内形成回流区,燃烧产物在内回流区生成。燃料和空气能够更有效地混合,从而消除了高温区,降低了NOX的排放,提高了燃烧效率。此外,随着旋流数的增加,径向流场分布得到改善,虽然最高火焰温度有所降低,但火焰换热面积却有所增加,使得辐射效率提高36.5%,NOX排放降低58.6%。为了解决旋流强度给稳定着火造成的两个相互对立和矛盾的问题,旋流数应控制在0.3-0.4为宜。China is rich in coalbed methane resources,its reserves rank third in the world,but the utilization rate is very low,and the utilization form is single,especially the low calorific value coalbed methane extracted underground.Because the methane concentration is only 10%-30%,at present,it mainly adopts the way of emptying,resulting in huge energy waste and environmental problems.Swirling combustion technology,by organizing fuel or oxidant into the burner in a swirling way to form a jet,using swirling combustion to optimize the combustion conditions,can effectively improve the combustion intensity and significantly improve the stability of the flame.A large number of engineering practices have verified that swirl combustion technology is suitable for the combustion of low calorific value gas.In this paper,the swirl combustion model of low calorific value coalbed methane is established by computational fluid dynamics.Based on the comparison and verification with the data of related literatures,the relationship between the swirl intensity of air incidence and the diffusion combustion characteristics of low calorific value coalbed methane is numerically simulated from the aspects of swirl flow field,flame temperature and radiation heat transfer.The results show that When the swirl number increases from 0 to 0.6,a recirculation zone is formed in the furnace,and the combustion products are generated in the inner recirculation zone.Fuel and air can be mixed more effectively,thus eliminating the high temperature zone,reducing NOx emissions and improving combustion efficiency.In addition,with the increase of swirl number,the distribution of radial flow field is improved.Although the maximum flame temperature decreases,the flame heat transfer area increases,which makes the radiation efficiency increase by 36.5%and NOx emission decrease by 58.6%.In order to solve the two opposite and contradictory problems caused by swirl intensity to stable ignition,the swirl number should be controlled between 0.3 and 0.4.

关 键 词：低热值煤层气 旋流燃烧技术 旋流强度 数值模拟研究 

分 类 号：TK16[动力工程及工程热物理—热能工程]