Combustion performance and slagging characteristics during co-combustion of Zhundong coal and sludge

Zhundong coal (ZDc) with a very large reserve is faced with severe problems of slagging and fouling during combustion in boilers because of the high-Na content. Sludge, the by-product of urban sewage treatment, is also faced with the problem in utilization. In this study, the co-combustion of ZDc and sludge was investigated in a laboratory-scale experimental apparatus before further studies in larger-scale setups. The experimental results confirm an interaction between ZDc and sludge during co-combustion, which was mainly caused by the Na catalytic action and improved the combustion performance of the co-fuels. The catalytic effect was particularly significant at low sludge mixing ratios. The reactions between Na-based compounds in ZDc and Si/Al/P-rich minerals in sludge, forming high-melting-point phosphates and aluminosilicates, not only increased Na retention in residual ash reducing the risk of fouling on tail-heating surfaces in boilers, but also raised the ash fusibility of the co-fuels avoiding low-temperature sintering. Even so, to prevent slagging, the high combustion temperature above 900 °C should be avoided during co-combustion because of the high Na retention in residual ash. Moreover, the high heavy metal retention in residual ash decreased the pollution caused by heavy metal volatilization during sludge combustion.     

Experimental investigation of ash behavior and emissions during combustion of Bosnian coal and biomass

This paper presents results of experimental research into the ash behavior of different Bosnian coal types and biomass fired in an electrically heated entrained pulverized fuel flow experimental reactor. The results are derived from a series of tests performed under a range of temperature and air conditions for the fuel test matrix. In essence, the experimental reactor comprises a 3 m length alumina–silicate ceramic tube, where combustion takes place, surrounded by SiC stick-type electric heaters and three-layer insulation. The temperature of the reaction zone is controlled by a programmable logic controller (PLC) with thyristor units for each of the heating zones, allowing the process temperature to be varied at will across the range from ambient to 1560 °C.     

Performance and emission characteristics of a turbocharged CNG engine fueled by hydrogen-enriched compressed natural gas with high hydrogen ratio

This paper investigates the effect of high hydrogen volumetric ratio of 55% on performance and emission characteristics in a turbocharged lean burn natural gas engine. The experimental data was conducted under various operating conditions including different spark timing, excess air ratio (lambda), and manifold pressure. It is found that the addition of hydrogen at a high volumetric ratio could significantly extend the lean burn limit, improve the engine lean burn ability, decrease burn duration, and yield higher thermal efficiency. The CO, CH₄ emissions were reduced and NO_x emission could be kept an acceptable low level with high hydrogen content under lean burn conditions when ignition timing were optimized.     

直喷式柴油机燃用生物柴油燃烧特性的研究

研究了柴油机燃用0#柴油和生物柴油的燃烧放热规律。通过对燃烧特征参数的计算分析,发现生物柴油的燃烧始点有所提前,滞燃期缩短;燃烧初期放热尖峰出现时刻对应的曲轴转角有所提前,瞬时放热率峰值下降;燃烧持续期延长。同时还比较了柴油机燃用生物柴油和0#柴油的经济性和排放特性,发现燃油消耗率上升12％左右,而各种排放污染物除NOx略有上升外,CO、HC和颗粒物(PM)均显著下降。     

替代燃料与煤混合燃烧的特点与应用前景

替代燃料与煤混合燃烧既可综合利用废物和煤炭资源,又能降低污染排放。阐述了替代燃料与煤混合燃烧的燃料特性、污染物排放和结渣特性,探讨了该技术目前的应用前景和存在的问题。     

污泥在流化床中的焚烧特性研究

本文研究了高水分、低热值的污泥在流化床中的结团特性、着火特性。考察了床温、污泥水分、辅助燃料、给料粒径、流化风速对污泥结团的影响，比较了多种不同污泥的结团情况，并运用中间相理论对污泥结团机理作了初步分析。试验结果对于污泥流化床焚烧的基础理论和应用研究都有着重要意义。     

1115型低排放柴油机的开发

为满足国家新的三轮汽车和低速货车尾气排放法规要求,山东华源莱动内燃机有限公司对自行开发的1115型柴油机的供油系统、燃烧室、凸轮轴等作了改进,这些改进措施有效地改善了柴油机的排放,本文论述了这些改进措施的效果及它对柴油机性能的影响。     

1115型低排放柴油机的开发

为满足国家新的三轮汽车和低速货车尾气排放法规要求,山东华源莱动内燃机有限公司对自行开发的1115型柴油机的供油系统、燃烧室、凸轮轴等作了改进,这些改进措施有效地改善了柴油机的排放,本文论述了这些改进措施的效果及它对柴油机性能的影响。     

KM496Q自然吸气涡流柴油机的研制

对KM496Q自然吸气涡流柴油机进行了优化设计，通过改进燃烧室设计，调整压缩比和喷油提前角，使用催化器等措施，使该机排放满足欧Ⅱ排放法规的限制。     

杭州市城市污水处理厂污泥处置方案探讨

在总结比较国内工程中得到应用的污泥处置技术的基础上,结合杭州市的实际情况,根据污泥处置方案选择原则,提出杭州市城市污水处理厂污泥的处置方案。     

乙醇与柴油混合燃料燃烧特性及排放特性的试验研究

在一台YC4112ZLQ增压柴油机上进行了不加任何助溶剂和着火改进剂的情况下,无水乙醇与柴油混合对柴油机燃烧过程影响的研究。试验结果表明,随着混合燃料中乙醇比例的提高,滞燃期延长,放热峰值增大,缸内最大爆发压力和最大压力升高率升高。与柴油相比,E10和E20有效热效率与原机相当,E30在高速大负荷工况热效率降低,NOx和碳烟排放明显降低;但HC和CO排放随着混合燃料中乙醇比例的增大,发动机转速为1500 r／min时,HC排放和CO排放均降低,发动机转速为2300 r／min时,HC排放和CO排放均有所升高。     

高速直喷柴油机的燃烧特性和排放试验研究

本文对一台四缸高速直喷柴油机的燃烧和排放特性进行了试验研究,分析研究了负荷及燃油喷射压力和供油提前角对该柴油机的着火延迟、瞬时放热率、NOx、CO及HC排放的影响。结果显示随着负荷及燃油喷射压力的提高着火延迟缩短、NOx排放增加;随着供油提前角的推迟NOx排放显著减少;而CO和HC的排放量与负荷及供油提前角的关系不大。     

An insight on hydrogen fuel injection techniques with SCR system for NOX reduction in a hydrogen–diesel dual fuel engine

Internal combustion engines continue to dominate in many fields like transportation, agriculture and power generation. Among the various alternative fuels, hydrogen is a long-term renewable and less polluting fuel (Produced from renewable energy sources). In the present experimental investigation, the performance and emission characteristics were studied on a direct injection diesel engine in dual fuel mode with hydrogen inducted along with air adopting carburetion, timed port and manifold injection techniques. Results showed that in timed port injection, the specific energy consumption reduces by 15% and smoke level by 18%. The brake thermal efficiency and NO_X increases by 17% and 34% respectively compared to baseline diesel. The variation in performance between port and manifold injection is not significant. The unburnt hydrocarbons and carbon monoxide emissions are lesser in port injection. The oxides of nitrogen are higher in hydrogen operation (both port and manifold injection) compared to diesel engine. In order to reduce the NO_X emissions, a selective catalytic converter was used in hydrogen port fuel injection. The NO_X emission reduced upto a maximum of 74% for ANR (ratio of flow rate of ammonia to the flow rate of NO) of 1.1 with a marginal reduction in efficiency. Selective catalytic reduction technique has been found to be effective in reducing the NO_X emission from hydrogen fueled diesel engines.     

车用多缸直喷柴油机燃用二甲醚的燃烧和排放特性研究

开展了4缸直喷柴油机燃用二甲醚时的燃烧和排放特性的研究。结果表明,适当增加喷油器伸出缸盖底平面的距离,采用流通截面较大的喷油器,降低启喷压力,可以提高CA498发动机燃用二甲醚时的热效率。燃用二甲醚时,发动机缸内的最大爆发压力和压力升高率低于燃用柴油时的情况。二甲醚发动机在所有工况下均可实现无碳烟排放,NO,排放约为柴油机的50％,CO和HC排放与柴油机相当。试验结果表明二甲醚是一种高效、低排放、燃烧噪声低的柴油机新型代用燃料。     

Performance and emission characteristics of a turbocharged spark-ignition hydrogen-enriched compressed natural gas engine under wide open throttle operating conditions

This paper investigates the effect of various hydrogen ratios in HCNG (hydrogen-enriched compressed natural gas) fuels on performance and emission characteristics at wide open throttle operating conditions using a turbocharged spark-ignition natural gas engine. The experimental data was taken at hydrogen fractions of 0%, 30% and 55% by volume and was conducted under different excess air ratio (λ) at MBT operating conditions. It is found that under various λ, the addition of hydrogen can significantly reduce CO, CH₄ emissions and the NO_x emission remain at an acceptable level when ignition timing is optimized. Using the same excess air ratio, as more hydrogen is added the power, exhaust temperatures and max cylinder pressure decrease slowly until the mixture’s lower heating value remains unchanged with the hydrogen enrichment, then they rise gradually. In addition, the early flame development period and the flame propagation duration are both shorter, and the indicated thermal efficiency and maximum heat release rate both increase with more hydrogen addition.     

甲醇-柴油混合燃料对发动机燃烧及排放特性的影响

在一台YTR3105直喷式柴油机上进行了小比例甲醇-柴油混合燃料发动机的燃烧及排放特性试验研究。结果表明:在相同的平均有效压力和转速下,随着甲醇含量的增加,燃料着火延迟相应增大,使得燃烧过程向上止点后移动。混合燃料的滞燃期比柴油长,预混燃烧放热率峰值增大,燃烧持续期缩短,缸内最大爆发压力和压力升高率增加。与纯柴油相比,甲醇-柴油混合燃料HC排放有所升高,但NOx和碳烟排放降低。大负荷时,CO排放显著下降。     

臭氧强化内燃机燃烧研究

对臭氧强化内燃机燃烧的机理进行了探讨;并采用高频高压脉冲洞面放电技术,成功地研制了一台柴油机用臭氧发生装置;利用该装置,以空气为原料产生臭氧,对进 含有一定浓度臭氧的柴油机的燃烧及排放性能进行了实验研究。实验结果表明,臭氧具有催化和强化内燃机燃烧的作用,臭氧助燃可通过改善燃烧达到节能和净化排放的目的。     

降低YC6108Q柴油机排气烟度的试验研究与改进探讨

排放作为发动机的重要质量指标,正越来越受到重视。本文介绍了影响柴油机排放烟度的主要因素的结果,并进行了分析总结。     

汽油机燃烧沉积物的形成及其对发动机排放特性的影响

汽油机燃烧沉积的累积，改变压缩比和传热，影响发动机性能。本介绍了作利用称重量法，在１６５Ｆ汽油机上进行燃烧沉积物积过程研究的实验结果，并探索了影响燃烧沉积物形成的几项因素，同时，在４９２Ｑ型汽油机上，进行了燃烧沉积物对发动机性能影响的影响实验研究。本研究结果可以为汽油机设计，使用及维修人员，汽油，机油等油料炼制工作提供科学依据。     

A numerical study on combustion and emission characteristics of premixed hydrogen air flames

Main challenges for micro power generators that utilize combustion process for energy production are inadequate residence time, destructive radical wall interactions and intensified heat loss which are mainly rooted from size limitation of such devices. To achieve high and uniform energy output, and bring in a solution to these challenges in an environment friendly manner without any kind of fundamental modification, effect of equivalence ratio on combustion and emission behavior of premixed hydrogen/air flames is numerically investigated in this study. For this purpose, an experimentally tested micro cylindrical combustor model is constructed and premixed hydrogen/air combustion in this model is simulated by varying equivalence ratio between 0.5 and 1.2 to find an optimal equivalence ratio with respect to drawbacks of micro power generators. Combustion and turbulence models implemented in this study are Eddy Dissipation Concept and Standard k-ε models, respectively. A detailed hydrogen/air reaction mechanism which consists of 9 species and 19 steps is employed to accurately gain insight into combustion process. Simulation results show that as the equivalence ratio decreases; centerline temperature distribution gets a lower value and the place where chemical reactions take place moves downstream. The most uniform temperature distribution is achieved between 0.8 and 1.0 equivalence ratios. The highest NO_x formation is at 0.9 equivalence ratio and its mass fraction decreases sharply when the equivalence ratio reduces from 0.9 to 0.5.