共查询到20条相似文献,搜索用时 578 毫秒
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考察了氢气/空气混合物燃烧时不同燃烧器结构和燃烧方式对NOx生成和回火的影响,指出,无混合室的空气外吸式燃烧器有较高的氢燃烧效率,并且氢燃烧时无回火,尾气中NOx的浓度也较低。 相似文献
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在一个流化床反应器和一个固定床反应器中研究了流化床煤燃烧中N2O及NOx生成的机理。发现流化床煤燃烧中N2O和NOx主要来自于煤中的氮,即挥发分氮和焦炭氮,部分NOx来自于空气中的N2。 相似文献
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流化床中高水分煤的燃烧与排放试验研究 总被引:1,自引:0,他引:1
通过在一小型流化床中进行高水分煤的燃烧与排放的试验研究,表明水分含量和空气-燃料比对于高水分煤的燃烧与排放有较大影响。随着水分增加,流化床床温下降,NOx、SOx排放量也下降。空气-燃料比存在一最佳值,这时床温最高,而偏离此值,床温下降,随着空气量的增加,NOx、SOx排放量也增加。当空气-燃料比变化时,燃烧干煤与燃烧高水分煤有着类似的试验结果。 相似文献
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燃煤流化床中N2O及NOx排放特性的试验研究 总被引:1,自引:0,他引:1
在一直径为100mm的小型燃煤流化床反应器中试验研究了床温、过量空气系数和煤种对N2O及NOx排放特性的影响。结果表明,随床温增加,N2O排放量减小,而NOx排放量增加。降低过量空气系数能同时减少N2O和NOx的排放量;且过量空气系数对N2O排放的影响与煤种有关。燃用含氮量高的煤,N2O和NOx的排放量也高。燃料氮转化为N2O、NOx的转换率与煤种有关,其中最主要的是挥发份含量。 相似文献
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在一个流化床反应器和一个固定床反应器中研究了流化床煤燃烧中N2O及NOx生成的机理。发现流化床煤燃烧中N2O和NOx主要来自于煤中的氮,即挥发分氮和焦炭氮.部分NOx来自于空气中的N2.挥发分氮主要以两种形式HCN和NH3均相反应生成N2O和NOx;焦炭氮则以多种多相反应方式生成N2O和NOxN2O与NOx的消减机理有很大的区别。N2O主要通过为氢原子和氧原子的还原的反应、床层中各种固态物质的催化还原及自身的热分解而减少。NOx则通过在固态物质催化下与CO、H2、NH3和焦炭的反应而减少。 相似文献
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锅炉低NOx排放煤粉分级燃烧的优化 总被引:1,自引:0,他引:1
燃料分级燃烧是目前广泛采用的降低NOx排放的有效方法之一。本文通过数值计算对优化煤粉分级燃烧进行了研究,以保证锅炉NOx低水平的排放,并确定了煤粉4级燃烧的组织原则。 相似文献
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通过数值模拟对某80 kW微型燃气轮机环形低氮燃烧室进行适当的改造并对其燃烧及NOx生成特性进行研究。研究结果表明:将烧天然气燃料的燃烧室改烧氨/氢混合燃料,在输出功率相同时燃料体积流量增大,通过增加燃料进气喷嘴的直径来降低燃料的进气速度;当掺氢比为0.3时,该结构的燃烧室燃烧不充分,燃烧效率达不到要求;当掺氢比在0.35~0.5、燃料华白数在19.9~21.7范围内变化时,该燃烧室可以实现高效稳定的燃烧,性能接近燃烧天然气燃料;氨/氢混合燃料中掺氢比增大,则NOx排放量也快速增大;由于燃料型NOx排放量占主导地位,该微型燃气轮机燃烧室不能实现低NOx燃烧,NOx排放远超国家标准,需要加装脱硝装置才能实际应用。 相似文献
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燃煤电站锅炉中的低NOx燃烧技术 总被引:5,自引:1,他引:5
本文针对我国NOx的排放情况及其主要来源,分析了NOx的生成途径。根据生成机理的不同比较分析了各种低NOx燃烧技术,包括低氧燃烧、浓淡燃烧、分级燃烧、废气再循环等技术。由于我国NOx排放以燃煤电站锅炉为主,因此本文主要讨论各种低NOx燃烧技术在电站锅炉中的应用。同时,对低NOx燃烧技术在工业锅炉及其它燃烧过程中的应用作了简要介绍。 相似文献
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《International Journal of Hydrogen Energy》2019,44(10):4996-5006
The most notable difference between linear hydrogen engine (LHE) and conventional crank hydrogen engine (CHE) is that the former supports variable motion operation for combustion optimizing. This article presents a study to reveal the effect of variable motion on hydrogen fuel diffusion and mixing of a direct injection LHE. A multi-dimensional model of coupled dynamics is proposed to describe the motion effect on mixture formation. The fuel mixing characteristic of the LHE is evaluated by comparing a corresponding CHE. Result indicates that compared with the CHE, the LHE behaves a slight lower uniformity of the hydrogen-air mixture during injection stage due to its slower motion, but the slower motion also provides longer time for hydrogen diffusion to form more homogeneous mixture before sparking ignition. Moreover, the effect of variable motion stroke on the hydrogen-air mixing of the LHE is also analyzed. Study reveals that the variable stroke has little effect on the hydrogen-air mixing during the injection stage, and the mixture uniformity varies in positive correlation with the stroke length at the occurrence of spark ignition. Suggesting that in order to achieve homogeneous combustion mode, the long motion stroke operation is a good choice for the LHE. 相似文献
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针对某650 MW超超临界燃煤锅炉在深度调峰过程中燃用大同烟煤时无法稳定燃烧的情况开展研究,就如何提高锅炉在低负荷运行中稳燃性的问题,对原煤种进行掺混改良,改变不同富氧燃烧配风方式,利用计算流体力学模拟软件模拟了不同工况的炉内燃烧情况。模拟结果表明:由于锅炉降低负荷运行增加了原煤种的着火难度,固定碳含量低且挥发分高的煤种可以较好适应锅炉运行调整;富氧燃烧可以提高锅炉低负荷运行时的出口烟温,能满足后续脱硝处理的要求;随着富氧燃烧程度的增大,煤粉燃烧耗氧量增加,每秒燃烧的煤粉颗粒数增加,加剧了炉内的燃烧,使燃烧更稳定;当富氧浓度大于27%时,不能高效提高炉内温度,NOx排放量增多;当富氧浓度为27%时,炉膛出口NOx排放量按6%O2折算为负增长的最小值,是该锅炉低负荷投运较为理想的工况。 相似文献
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氢燃料发动机燃烧与排放控制研究进展 总被引:2,自引:0,他引:2
围绕氢燃料作为车用发动机理想代用燃料这一主题,全面论述氢燃料发动机混合气的形成规律和点火技术;剖析氢发动机的异常燃烧机理和NOx的排放机理;分析影响氢燃料发动机排放的主要因素;总结异常燃烧和NOx排放的控制技术。 相似文献
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对某电厂一台300 MW四角切圆锅炉低氮改造后的NOx生成特性进行了数值模拟计算,分析了燃尽风率对NOx生成特性的影响。分析结果表明:燃尽风率增大时,在主燃烧区喷入空气量减少,导致煤粉燃烧不完全、温度降低;燃尽区的富氧氛围使未燃尽的煤粉进一步完全燃烧;主燃烧区的还原性氛围使得该区域NOx会随着燃尽风率的增大而减少;燃尽区的高温以及较低的CO浓度降低了该区域的还原性氛围,使NOx排放量增加。综合考虑NOx排放和消旋效果,该炉型锅炉采用30%的燃尽风率是比较合理的。 相似文献
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大型锅炉高效低NOx燃烧技术的研究 总被引:29,自引:0,他引:29
本文详细分析了NOx生成机理 ,低NOx燃烧器以及炉内空气分级燃烧的机理及其影响因素 ,并对 30 0MW贫煤锅炉高效低NOx燃烧技术进行优化模拟 ,对OFA优化设计作了介绍。为修改制定大型贫煤锅炉NOx排放标准及大型锅炉优化设计与运行提供了科学依据 相似文献
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《International Journal of Hydrogen Energy》2019,44(47):26000-26011
Based on the dual challenges of the global energy crisis and environmental pollution, hydrogen has been recognized as an ideal alternative internal combustion engine (ICE) fuel. To improve the combustion efficiency of hydrogen direct injection ICE, we numerically analyzed the effects of different injection parameters, including injection timing, injection pressure, and dual injection, on the formation of a hydrogen-air mixture using the CONVERGE software from the perspective of mass transfer and flow state. It was determined that it is enough to set the injection timing to −88° after top dead center (ATDC) for both uniform mixture and desirable indicated thermal efficiency (ITE). However, when the injection timing is set to −43° ATDC, an acceptable ITE and effective combustion can be achieved by employing the “jet-room coordination” effect of the ω chamber. Injection pressure has a minimal effect on mixture formation and combustion. In contrast, the timing and mass fraction of secondary injection have a significant influence on tumble strength, which is a key factor for the mixture improvement. 相似文献
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《International Journal of Hydrogen Energy》2022,47(23):12015-12023
In order to achieve a more thorough understanding of the impacts of vitiation on supersonic combustion, a series of numerical simulations are performed to investigate the shock-induced combustion of hydrogen-air mixtures. Direct comparisons are made between electric heating, in which the mixture is brought up to the designated temperature without modifying its composition, and vitiated heating, in which the mixture is heated by the products of hydrogen-air combustion. While the cases with electric heating have much higher thermicities than the cases with vitiation at a given condition, vitiated heating tends to have smaller induction lengths than electric heating for lower temperatures and richer mixtures. At reasonable residence times, this decrease in induction length is primarily caused by the presence of nitric oxide in the vitiated mixture and not by hydroxyl or hydrogen radicals, which implies that nitrogen chemistry cannot easily be neglected in studies of supersonic ignition and detonation. 相似文献