共查询到20条相似文献,搜索用时 0 毫秒
1.
利用Fluent软件对1台900 MW四角切圆燃烧锅炉在不同负荷下炉内燃烧过程进行了数值模拟,分析了负荷变化对炉内流动和传热的影响规律.结果表明:在高负荷工况下运行时,炉内燃烧充分且稳定,但是炉内火焰更容易冲刷水冷壁,可能发生局部结渣现象;在低负荷工况下运行时,炉内火焰充满度较差,切圆燃烧的稳定性显著下降,炉膛水冷壁灰污表面温度也相应降低,水冷壁表面结渣的倾向弱化,沿高度方向水冷壁吸热不均匀性增大.由于该锅炉的低NOx燃烧器采用了分离燃尽风,使得高温区扩展,火焰中心高度比采用有关标准推荐的方法计算所得结果高4~5 m. 相似文献
2.
3.
4.
SandroDal-Secco 《热科学学报(英文版)》2000,9(4):376-380
IntroductionThe developments relative to coal combustion havebeen performed into a general purpose 3D code namedESTET under quality assurance, and used to modelcomplex turbulent reactive flows. In the case ofindustrial boilers we can assume a no-slip conditionbetween gas and particles which is the case for the mostpart of the furnace, except possibly in the near field ofthe burners. With such an assumption, the equations for apafticle-gas fixture with a mean density can be written.The combu… 相似文献
5.
6.
7.
INTroDUCTIONThe Horizontal Bias Combustioll Pulverized Coal(HBC) burner for tangential firing system has advantages of improving flame stabilization, slaggingresistance, pollution control and high combustionefficiency[']. However, in the thin and tall furnace firedwith coal with strong slagging telldency) it is possiblethat slagging occurred on water-cooled wall, especiallywhen the cross-sectional and volumetric heat releaserate are very high in the burner domain.The HBC burner with Si… 相似文献
8.
9.
10.
11.
12.
《能源学会志》2020,93(4):1713-1725
As an emerging clean coal combustion technology, Moderate or Intense Low-Oxygen Dilution (MILD) combustion or oxy-fuel combustion, compared with traditional coal combustion, has many advantages. However, compared with MILD combustion and oxy-fuel combustion, MILD-oxy combustion is believed more attractive. In this work, MILD-oxy combustion characteristics with oxygen concentrations from 10% to 50% are studied numerically. The results show that within a certain range, increasing the oxygen concentration is in favor of MILD-oxy combustion performance close to that of MILD-air combustion. When the oxygen concentration is higher enough, the momentum reduced by the increase of oxygen concentration has a great influence on the furnace temperature. With the increase of oxygen concentration, the radiation heat transfer is enhanced and the convective heat transfer is weakened. The increase of oxygen concentration can promote the occurrence of char gasification reaction with CO2. In addition, MILD-oxy combustion has a large impact on CO emission. 相似文献
13.
The progression of ignition was numerically simulated with the aim of realizing a full-scale tiny-oil ignition burner that is identical to the burner used in an 800 MWe utility boiler. The numerical simulations were conducted for four excess air ratios, 0.56, 0.75, 0.98 and 1.14 (corresponding to primary air velocities of 17, 23, 30 and 35 m/s, respectively), which were chosen because they had been used previously in practical experiments. The numerical simulations agreed well with the experimental results, which demonstrate the suitability of the model used in the calculations. The gas temperatures were high along the center line of the burner for the four excess air ratios. The flame spread to the burner wall and the high-temperature region was enlarged in the radial direction along the primary air flow direction. The O2 concentrations for the four excess air ratios were 0.5%, 1.1%, 0.9% and 3.0% at the exit of the second combustion chamber. The CO peak concentration was very high with values of 7.9%, 9.9%, 11.3% and 10.6% for the four excess air ratios at the exit of the second combustion chamber. 相似文献
14.
数值模拟是研究工程气固多相流中辅助试验方法的一种强有力的工具,本文采用数值模拟方法,对东锅DG440/13.7 -Ⅱ2型循环流化床锅炉的燃烧进行了研究,计算分析了炉内的流动、温度分布情况,对锅炉的优化设计和运行提供有益的指导. 相似文献
15.
散热是影响微尺度燃烧器燃烧稳定性的重要因素之一.本实验通过在一个长40 mm、内径2 mm、外径4 mm的石英玻璃直圆管表面施加不同的外部吹风温度,控制其表面散热.研究4、107、756℃外部风温下,微燃烧器的工作性能,其中燃料混合气体流量为0.16、0.28、0.32 L/min.实验测得燃烧器壁面温度,结合数值模拟研究内部燃烧过程.计算结果显示,提高燃料流量或外部风温可以提升反应强度、抑制熄火.如在风温107℃时,燃料气体当量配比下,当流量由0.16 L/min上升到0.32 L/min时,峰值温度由1538 K上升到1620 K;在流量0.28 L/min时,燃料气体当量配比下,当外部风温由4℃上升到756℃时,峰值温度由1592 K上升到1731K. 相似文献
16.
17.
对生物质锅炉进行了生物质颗粒的燃烧试验,以了解其燃烧情况,同时进行了生物质颗粒燃烧的数值模拟,分析研究炉内的速度场、温度场和组分浓度场。对比数值模拟和试验数据,可知烟气出口处温度与数值模拟结果吻合较好,且锅炉燃烧性能良好,试验还测得在烟气出口处温度较高易结焦,可为以后锅炉改造提供方向。 相似文献
18.
19.
为了解决化石燃料储备不足与环境污染问题,生物质燃料作为石油替代能源得到大力提倡,如何合理地将化石燃料替换为生物质燃料且维持设备正常运行成为工程上亟待解决的问题。本文采用CFD软件研究了车载5 kW生物乙醇微型燃烧室的燃烧特性,对比分析了不同功率(0.5~5 kW)和出口温度(840~960 K)时的回流区长度与宽度、回流量、出口温度分布系数(OTDF)、出口NO体积分数等特征参数。结果表明:随着出口温度升高,回流区长度逐渐缩短,回流量减少,出口温度均匀性逐渐变差,出口NO体积分数明显增加;随着燃烧室功率增大,回流区长度变长,回流量增加,OTDF先增大后减小,NO体积分数随着功率的降低而显著升高,最大值出现在1 kW时,达到满负荷时的7倍。因此,为了实现稳定燃烧和减少污染物排放,该乙醇微型燃烧室应在较高的空燃比(即较低的出口温度)和功率下运行。 相似文献