CLALIFICATION OF FUNDAMENTAL PHENOMENA ON NON-EMISSION BURNING OF CO_2AND NOx

CO_2和NOx非排放燃烧基本现象的澄清

基本信息

批准号：
10450078
负责人：
NIIOKA Takashi
金额：
$ 5.31万
依托单位：
TOHOKU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

项目摘要

To develop a combustion system that is suitable for CO_2 recovery and has less emission of pollutants, a new combustion method using CO_2/O_2as oxidant has been proposed. However, the epically thin and gray-gas radiation model with Planck mean absorption coefficient, which has no reabsorption, has overestimated the emission, especially for "low-speed" flames. The effects of nongray radiation on the propagation and flammability limit of premixed CH_4/O_2/CO_2 flames were numerically analyzed. The results can be summarized as follows :1. The nongray radiation effects described by the statistical narrow-band (SNB) model on the laminarburning velocity and flammability limit become larger as the dilution ratio of CO_2 is increased.2. The gray radiation described by the optically thin model (OTM) loses effectiveness for higher CO_2 dilution ratios and lower equivalence ratios.An experimental and numerical study of diluent (CO_2 or N_2) effects on structure and stability of axisymmetric lifted laminar diffusion CH_4/(Diluent+O_2) flames were also performed over a wide range of the dilution ratio, Z.Results showed that3. As increasing the Z, attached flames are lifted off at the Z_<lim> (0.72 for CO_2, 0.83 for N_2 diluted flame, respectively) and there were steady responses that the flame length. L_f, shortened and the lift off height, H_f, increased as well as the spreading out of the flame base in the radial direction until the Z_b (0.78 for CO_2, 0.86 for N_2 diluted flame, respectively).4. The leading edge structure of the lifted flame has a triple flame, where fuel rich premixed wing is smaller than lean one and the trailing nonpremixed flame inclines immediately to the fuel side from trip point.5. It is also shown that CO_2 effects are stronger than N_2 on the structure and stability due to high heat capacity and low transport rate of Co_2.

为了开发适合CO_2恢复且污染物发射较少的燃烧系统，已经提出了一种使用CO_2/O_2AS氧化剂的新燃烧方法。但是，没有重吸收的普朗克平均吸收系数的平均薄和灰色气体辐射模型高估了发射，尤其是对于“低速”火焰。对Nongray辐射对预混合CH_4/O_2/CO_2火焰的传播和易燃性极限的影响进行了数值分析。结果可以总结如下：1。随着CO_2的稀释比增加，统计狭窄波段（SNB）模型描述的Nongray辐射效应对层流速度和可燃性极限变得更大。2。光学薄模型（OTM）描述的灰色辐射对较高的CO_2稀释比和较低的等效比失去了有效性。稀释剂（CO_2或N_2）对轴对称升高的层状层状层状层状层扩散CH_4/（稀释剂CH_4/（稀释剂）的实验和数值研究+o_2）在稀释比的范围内进行火焰，z。结果表明3。随着Z的增加，附着的火焰在Z_ <lim>上抬起（CO_2的0.72，分别为N_2稀释的火焰为0.83），并且有稳定的响应，即火焰长度。 l_f，缩短和升降高度H_F，增加了径向方向的散布，直到Z_B（CO_2为0.78），分别为N_2稀释火焰为0.86）.4。抬起火焰的前缘结构具有三重火焰，燃料富含燃料的预制机翼小于瘦的翼，而尾随的未构图的火焰立即倾斜到Trip Point.5。还表明，由于高热容量和较低的CO_2的运输速率，CO_2效应对结构和稳定性的效果强于N_2。