单井燃气加热炉燃烧器低氮氧化物排放研究

对50 k W单井燃气加热炉的自然引风扩散式燃烧器进行文献分析和燃烧机理研究,结合CFD数值模拟,计算自然引风扩散式燃烧器在不同过剩空气系数下NO_x和CO排放量,分析全预混燃烧器在不同过剩空气系数(燃气空气混合物温度为27℃)和不同混合气初始温度(过剩空气系数为1.5)下NO_x排放量及低氮排放的技术要求。分析结果表明,自然引风扩散式燃烧器的污染物排放不能满足当前要求,全预混燃烧技术更适合小型单井燃气加热炉的低氮改造;在燃烧器改造中,全预混燃烧器应满足高过剩空气系数下稳定运行、混合气隔热良好等技术要求。     

冷热电三联供系统研究(8):雾霾与脱硝

氮氧化物(NOx)是导致雾霾天气的重要原因之一,天然气虽然属于清洁能源,但是燃气冷热电三联供系统(CCHP)烟气中的NOx仍然超过了国家标准规定的限值,必须加以处理。说明了NOx造成大气污染的机理,介绍了与燃气CCHP系统大气污染物排放有关的标准,给出了过量空气系数和氧含量、NOx体积分数和质量浓度之间的关系,分析了CCHP系统烟气中NOx的来源和反应机理,阐述了燃气CCHP系统脱硝的现行技术,指出干式低氮燃烧技术和铁基分子筛选择性催化还原法(SCR)是目前燃气CCHP系统较先进的脱硝技术。     

燃气热水器火排片引射燃烧一体化数值模拟

建立燃气热水器火排片引射燃烧一体化计算模型,通过数值模拟的方法研究预混气体流动特性及热工参数(过剩空气系数、火孔宽度)对燃烧特性的影响规律。研究结果表明:火排片内部存在强弱不同的回流区,影响火孔出口速度的均匀性。随着过剩空气系数的增加,燃烧室内高温区域明显减小,燃烧室出口处NO质量浓度先减少后增加,CO质量浓度保持降低趋势;在过剩空气系数1.3～1.6范围内,增大过剩空气系数可以降低CO和NO质量浓度。随着火孔宽度的增加,燃烧室内高温面积略有升高,燃烧室出口处NO质量浓度不断增加,CO质量浓度不断减小。相比于过剩空气系数,火孔宽度对燃烧室内温度分布特性影响较小。     

全预混表面燃烧污染物排放特性的实验研究

对全预混表面燃烧污染物排放特性进行了实验研究,实验结果显示NO_x排放量随过剩空气系数增加而降低。进而综合考虑过剩空气系数对燃烧热效率和NO_x排放水平的影响,给出了全预混表面燃烧过剩空气系数的建议值。     

楼宇型天然气冷热电联产系统经济性分析

总结了10 a内居民、商业、工业用天然气和电的价格变化规律,以实际能源价格数据为依据进行了经济性分析。运行时间按26 000 h计算,以单位发电量的经济收益为指标,建立了燃气内燃机和小型燃气轮机2种常用原动机系统的计算模型,对住宅、商业、工业建筑应用冷热电联产(CCHP)系统的经济现状进行了定量分析。结果表明:在现有价格体系下,建筑应用冷热电联产不具有经济效益;随着燃气价格的上涨,楼宇型CCHP的经济效益变差;经济困局的症结是我国现行的能源价格机制不利于楼宇型CCHP的发展。认为楼宇型CCHP的经济困局是局部的、暂时的,转变楼宇型CCHP的自发电利用模式是解决经济困局的有效途径。     

扩散式分段燃烧氮氧化物排放特性模拟研究

在给出氮氧化物生成机理的基础上,采用摸拟软件研究了扩散式分段燃烧不同过剩空气系数和一次空气系数对氮氧化物排放的影响。对于扩散式分段燃烧,随着一次空气系数的增加,氮氧化物排放浓度呈先增大后减小的趋势,存在峰值。一次空气系数取0.5,过剩空气系数在1.1~1.2范围取值时,可以得到较低的氮氧化物排放浓度。     

沼气红外燃烧技术在粮食干燥器中的应用研究

为了降低粮食糜烂损失、解决传统谷物干燥机能耗高、污染大、效率低的问题,本文将红外加热技术应用于粮食干燥领域,设计了一种以沼气为燃料的全预混燃气红外干燥系统,并对该系统的红外燃烧性能展开研究。结果表明:该系统燃烧状态良好,燃烧器的CO、NOX排放浓度均低于50×10~(-6),可以满足污染物的排放要求;过剩空气系数和表面热强度对烟气中CO、NOX的排放浓度有较大影响;过剩空气系数由1.1增加至1.51时,烟气中CO浓度由39×10~(-6)降低至14×10~(-6),NOX浓度由15×10~(-6)降低至6×10~(-6);表面热强度由0.2W/mm2增加至0.4W/mm~2,烟气中CO浓度增加110%,NOX浓度增加66.7%。     

CCHP系统节能减排计算方法研究(1):碳排放计算方法

燃气CCHP是减少CO_2排放的重要措施,准确地计算CCHP系统碳排放量对于国内即将全面实施的碳交易市场事关重大。分析了现有的CCHP系统碳排放计算方法存在的问题,提出了适用于燃气CCHP系统的碳排放计算方法,给出了工程实例计算结果。     

燃气-空气双分级低氮燃烧器数值模拟

研究设计了燃气-空气双分级低氮燃烧器,通过CFD软件FLUENT建立低氮燃烧器三维数值模型,并进行模型验证,模拟结果与实际情况较为吻合,能够较为准确地预测NO_x生成量的变化规律。主要从燃气配比、一级过剩空气系数及内筒直径3方面对燃料-空气双分级结构进行研究,寻求燃烧特性和NO_x生成规律。研究发现:燃气分级对温度分布及NO_x排放具有重要的影响,当一级燃气配比为10%时,火焰分配较为分散,温度低且高温区域较少,NO_x质量分数较低。二级燃烧区对NO_x生成影响作用弱于一级燃烧区,一级燃烧区的状态为燃烧器NO_x生成的主要影响因素。一级过剩空气系数宜处于0.7～1.45范围,考虑到燃烧稳定性,一级过剩空气系数应取较小值。内筒直径适量增大,可以达到改善一级燃烧状态,降低NO_x排放的目的。     

小型热电联供系统试验研究

采用内燃机改装技术,将汽油内燃机改装成燃气内燃机,构建了小型燃气内燃机热电联供试验系统。对试验系统的发电效率、热回收效率等进行了测试分析。随着负载增加,发电效率增大,热回收率减小,而热电联产总效率变化不大,最高可达82%。     

燃气机热泵在暖通空调中的应用

本文阐述了燃气机热泵的工作原理,通过对该设备系统与一般热泵的比较,指出燃气热泵的特点,并对国内外研究和应用发展状况进行了回顾,探讨了燃气机热泵在暖通空调中应用的方法,对其节能效果进行了分析,结果表明采用燃气机热泵具有较高的能源利用系数,指出了燃气机热泵在暖通空调中具有广泛应用的前景。     

Performance analysis of vortex flow through a swirler by computational fluid dynamics technique

ABSTRACT

In the recent era, it is preferred for energy to be produced from renewable energy resources rather than from non-renewable resources. That’s why the non-renewable sources gradually become obsolete due to its main drawback of creating pollution. On the other hand, the set-up cost for renewable energy resources is very high, so it is difficult to afford financially. Therefore, researchers started their research on pollution control from the non-renewable resources. In this work, the emission level of diesel engine has been successfully planned to control by inducing a variable geometry swirler in the inlet manifold, which will enhance the turbulence inside the cylinder, hence increasing homogeneity between air–fuel composition and low emission. In this paper, it has been shown numerically and justified how the designed geometry of the swirler will increase the efficiency of combustion to control the emission from an I.C. engine.     

Emission analysis of a CI engine during cold weather conditions using pre-heated air and engine using waste energy and phase-change material

Environmental pollution due to emissions from an IC engine is an important problem appearing under cold weather conditions. In this study, air pre-heating as well as pre-heating of the IC engine is done to ensure efficient combustion and reduction in emission level during a cold start. A thermal energy storage device (TESD) and an air pre-heater is designed and tested for the purpose of pre-heating. The TESD contains paraffin as a phase-changing material which works on the principle of absorption and rejection of thermal energy during the phase-changing temperature Normal, discharge and pre-heat emissions for diesel and different blends of Karanja oil are compared. From the experiment, it is observed that carbon monoxide (CO), hydrocarbon (HC) and smoke emissions are reduced during engine pre-heating and air pre-heating compared to normal condition with respect to increase in time and load at compression ratio 18.     

CI engine performance during cold weather condition using preheated air and engine by waste energy

ABSTRACT

The aim of the current research is to experimentally investigate the performance, combustion and emission parameters of a compression ignition engine in the discharging and air preheating mode during the cold weather condition. For preheating the engine, a thermal energy storage device using phase-change material (PCM) and for preheating the inlet air an air preheater is used. From the results, it is observed that the engine temperature increases with time from 15°C to 27°C in 840?s. PCM temperature rises from 15°C to 60°C in 3000?s. during charging and while in discharging it decreases from 45°C to 30°C within the same time period. Brake thermal efficiency increases and brake-specific fuel consumption decreases with increase in load. Air-preheated diesel gives maximum cylinder pressure as compared to normal diesel. Carbon monoxide and hydrocarbon emissions are reduced during discharging and air preheating as compared to cold weather emission.     

Effect of injection pressure on the performance and emission characteristics of CI engine using canola emulsion fuel

Biodiesel is a promising renewable alternative fuel for diesel. The need of biodiesel fuels for the diesel engines is to restrict the dependency on the fossil fuels in context to the world energy oil crisis. The objective of this article is to investigate the performance and emission characteristics of a CI engine with diesel and blends of canola biodiesel Emulsion at 200, 220 and 240?bar. The fuel injection system in a diesel engine is to achieve a high degree of atomisation for better penetration of fuel in order to utilise the full air charge and to promote the evaporation in a very short time and to achieve higher combustion efficiency. Emulsified fuels showed an improvement in brake thermal efficiency of 28.8% at 240?bar accompanied by the drastic reduction in NOx at 200?bar.     

天然气分布式能源系统烟气脱硝方案

对微型燃气轮机、燃气内燃机发电机组的排放特性(针对氮氧化物)进行分析,当使用场所对氮氧化物排放指标要求较严格时,后者需设置烟气脱硝装置。结合工程实例,对配置燃气内燃机组的分布式能源系统烟气脱硝方案进行了探讨。     

Influence of modified pent roof combustion cavity on diesel engine performance and emission characteristics

The utmost vital role of the IC engine burning chamber is to offer correct mixing of air and fuel in a little time to lessen the ignition lag phase, which determines the quality of the combustion, performance and the exhaust emission characteristics. To attain this, a systematised air movement termed ‘air swirl’ is offered to create high comparative velocity amongst fuel droplets and air. In this work, the engine piston head is modified to a 6° angle at the crown part, and the engine performance and emission analysis are carried out. The modified piston promotes speedier mingling between the inducted air and injected fuel, which speeds up the combustion process. By modifying the combustion chamber, we obtained a very less amount of NO_x Emissions and a moderate amount of hydrocarbon and carbon monoxide emissions.     

一种低过量空气系数的浓淡燃烧器

从节能减排的目的出发,采用低过量空气系数和浓淡燃烧技术设计一个新型的燃烧器用于家用燃气热水器。确定燃烧器的基本结构后对其进行试验,得出结构上关键的二次风孔的分布结果以及燃烧室内的火焰情况,并分析这种新型燃烧器的可行性。     

新型进气预处理装置对汽油机性能影响的研究

一台16气门四缸汽油机,安装一种新型进气预处理装置．试验结果表明,发动机的外特性试验燃油比油耗最多可降低9％,废气排放品质也有一定程度的改善．对其进行实车道路试验也具有同样的效果,燃油消耗量减少2．94％．显示出该装置对减少燃油消耗以及降低汽车尾气排放具有良好的应用前景．