Engine performance and combustion characteristics of a direct injection compression ignition engine fueled waste cooking oil synthetic diesel

Biodiesels produced from various feedstocks have been considered as alternative fuels used in internal combustion engines without major modifications.This research focuses on producing biodiesel from waste cooking oil(WCOSD)by the catalytic cracking method using MgO as the catalyst and comparing the engine operating characteristics of the test engine when using WCOSD and traditional diesel(CD)as test fuels.As a result,the brake power of the test engine fueled WCOSD,and traditional diesel is similar.However,the engine fuel consumption in the case of using WCOSD is slight increases in some operating conditions.Also,the nitrogen oxides emissions of the test engine fueled WCOSD are higher than those of CD at all tested conditions.The trend is opposite for hydrocarbon emission as the HC emission of the engine fueled by WCOSD reduces 26.3%on average.The smoke emission of the test engine in case of using WCOSD is lower 17%on average than that of CD.However,the carbon monoxide emissions are lower at the low and medium loads and higher at the full loads.These results show that the new biodiesel has the same characteristics as those of commercial biodiesel and can be used as fuel for diesel engines.

Influence of different oil feed rate on bituminous coal ignition in a full-scale tiny-oil ignition burner

To reduce oil consumption during firing-up and partial-load operation, a tiny-oil ignition burner has been recommended. Through reacting-flow experiments performed on a full-scale experimental setup, the influence of different oil flow rates on bituminous coal combustion as well as flow rates without coal feed was analyzed. The ignition burner is identical to that normally used in an 800 MWe utility boiler. Under operating conditions with flow rates of 50, 100, and 150kg/h, gas temperature distribu- tions were measured in the burner. At the equivalent measuring points at the exits of the first and second combustion chambers, these distributions remained almost unchanged under a constant coal feed rate of 4t/h. However on the burner centerline, distributions increased slightly with increasing flow rate. Different gas concentrations were measured at the center of the burner exit. For instance, the 02 concentration at the burner exit varied from 0.01% to 0.31% whereas CO concentrations were more than 10000 ppm. At the same coal feed rate of 4 t/h, burner resistances are 480, 600, and 740 Pa for oil flow rates of 50, 100, and 150 kg/h, respectively.

Performances and emissions of a petroleum coke oil slurry engine

In order to solve the failure of fuel system when using petroleum coke oil slurry (PCOS) in a R180 diesel engine directly,a petroleum coke oil slurry fuel system (PCOSFS) was developed and installed in R180 engine,which was called PCOS engine.In order to analyze performances and emissions of the PCOS engine,a comparative experiment between PCOS engine fueled with PCOS and R180 engine fueled with diesel oil was carried out.The results show that the PCOS engine can run smoothly,the maximum output power decreases by about 6.2% and 19.0% and the maximum brake thermal efficiency reduces by around 5.85% and 4.13% as compared to R180 engine under the conditions of 1 200 and 1 600 r/min.The HC emissions of PCOS engine are lower than those of R180 engine at 1 200 r/min,and are close to those of R180 engine at 1 600 r/min.The CO emissions are similar to R180 engine at 1 200 and 1 600 r/min.The smoke intensity is close to R180 engine at 1 200 r/min,and is higher than R180 engine at 1 600 r/min.The particles emitted from PCOS engine array sparsely,but particles emitted from R180 engine array closely,cohering together.

Numerical simulation of combustion characteristics at different coal concentrations in bituminous coal ignition in a tiny-oil ignition burner

With the objective of producing a full-scale tiny-oil ignition burner, identical to the burner used in an 800 MWe utility boiler, numerical simulations were performed using Fluent 6.3.26 to study the progress of ignition for four coal concentration settings covering sub- operation conditions prevailing during the experiments performed with the burner. The numerical simulations conformed to the experimental results, demonstrating the suitability of the model used in the calculations. Simula- tions for a coal concentration of 0.40 kg/kg corresponding to a single burner operating at its rated output were also conducted, which indicated that gas temperatures along the burner centerline were high. As gas flowed to the burner nozzle, the high-temperature region expanded, ensuring a successful pulverized-coal ignition. With increasing coal concentration （0.08-0.40 kg/kg）, the gas temperature along the burner centerline and at the first and second combustion chamber exits decreased at the equivalent radial points. At the center of the second combustion chamber exit, the O2 concentrations were almost depleted for the five coal concentrations, while the CO concentrations peaked.

Numerical simulation of bituminous coal combustion in a fullscale tiny-oil ignition burner： Influence of excess air ratio

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 bumer 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.

Study on the Thermal Ignition of Gasoline-air Mixture in Underground Oil Depots based on Experiment and Numerical Simulation

The study on the special phenomenon,occurrence process and control mechanism of gasoline-air mixture thermal ignition in underground oil depots is of important academic and applied value for enriching scientific theories of explosion safety,developing protective technology against fire and decreasing the number of fire accidents.In this paper,the research on thermal ignition process of gasoline-air mixture in model underground oil depots tunnel has been carried out by using experiment and numerical simulation methods.The calculation result has been demonstrated by the experiment data.The five stages of thermal ignition course,which are slow oxidation stage,rapid oxidation stage,fire stage,flameout stage and quench stage,have been firstly defined and accurately descried.According to the magnitude order of concentration,the species have been divided into six categories,which lay the foundation for explosion-proof design based on the role of different species.The influence of space scale on thermal ignition in small-scale space has been found,and the mechanism for not easy to fire is that the wall reflection causes the reflux of fluids and changes the distribution of heat and mass,so that the progress of chemical reactions in the whole space are also changed.The novel mathematical model on the basis of unification chemical kinetics and thermodynamics established in this paper provides supplementary means for the analysis of process and mechanism of thermal ignition.

660 MW高水分褐煤机组等离子体点火技术应用

等离子体点火技术变负载灵活性高,点火启动时间短,有害气体排放低,经济效益好,在煤电机组深度调峰改造中应用广泛,是电站锅炉实现低负荷稳燃的主要措施之一。近年来,中速磨煤机在燃用高水分褐煤机组中的推广为高水分褐煤等离子体无油点火技术的应用提供了便利条件。然而,传统等离子体点火技术多适配于烟煤等优质煤种,对于燃用高水分低热值褐煤存在点火能量不足、需油枪辅助点火、燃油经济性差等问题。为此,开发了偏置浓缩狭缝式进粉多级筒结构等离子体点火煤粉燃烧器,在某入炉原煤全水分35%~40%的660 MW褐煤基建机组锅炉上开展变工况等离子体无油点火试验,分析了入炉煤质及机组操作参数对高水分褐煤无油点火特性的影响。基于点火试验结果,提出了等离子体燃烧器改进方案,在基准工况下,对高水分褐煤等离子体燃烧器进行数值模拟,对比讨论了燃烧器改造效果。点火试验结果表明,新型等离子体点火系统可点燃发热量10900~13400 kJ/kg的高水分褐煤,并实现机组无燃油启动,点火能力较强;燃烧器对煤质适应范围较小,点火能量过大,燃烧器中心筒与二级筒间隙较小,冷却效果较差,二级筒易超温,造成等离子体燃烧器二级筒结焦烧损;机组稳燃时,燃用胜利褐煤并投运等离子体发生器对锅炉NO_(x)排放基本没有影响。数值模拟结果表明,点火试验所用燃烧器由于一级燃烧筒内煤粉吸收等离子体热量过于集中而提前燃烧,燃烧筒壁面超温,导致内壁结焦;改进后燃烧器一、二级燃烧筒内中心火焰温度显著降低,在三级燃烧筒末端火焰温度趋近一致,燃烧器壁面最高温度为376℃,较改进前降低约74℃;改进方案减少了浓煤粉对一级燃烧筒入口端面的冲刷,提高了一级燃烧筒内煤粉量,优化了点火过程。因此,开发并优化新型等离子体燃烧器可实现宽煤质范围高水分褐煤机组稳定高效点火,为建成国内首座高水分褐煤无油电厂提供技术支撑。

燃煤锅炉点火系统甲醇替代柴油改造探析

介绍了燃煤锅炉几种常用的点火方式。针对长青能化公司3台燃煤锅炉柴油点火及稳燃系统存在的点火和稳燃过程中油雾燃烧不完全、排放黑烟、尾部除尘器布袋阻力大等问题,利用自产清洁绿色甲醇替代柴油作为燃料,对柴油点火及稳燃系统进行了改造。改造后彻底解决了上述问题,还可节约48%的燃料费用。此外,还解决了甲醇点火及稳燃系统出现的新问题。

少油点火系统控制逻辑保护现状分析

少油点火系统是火电企业重要节能设施,是锅炉炉膛安全监控系统的重要组成部分。各企业少油点火系统的控制逻辑不同,现有控制逻辑不完全符合新标准要求,机组安全生产存在较大隐患。尤其是少油点火参与到炉膛安全监控系统系统的全炉膛火焰丧失和全炉膛灭火保护,锅炉投煤初期燃烧不佳,煤火检丧失,该保护不会动作,存在锅炉爆燃的可能。为此,对36台机组的少油点火系统控制逻辑进行了专项调研,通过对在运机组调研,对少油点火系统控制逻辑存在的问题进行整理分析,结合标准相关要求,提出控制逻辑优化建议,以提高火电机组安全性。

基于Phast-QRA的某油田拉油点密闭储油罐闪燃事故后果模拟分析

采用Phast-QRA软件对某拉油点密闭储油罐发生的闪燃事故进行事故后果模拟定量分析。根据事故发生时的场景及相关参数通过软件模拟计算出密闭储油罐在发生事故的死亡半径、重伤半径和轻伤半径等参数,模拟计算出事故的最大影响范围和严重程度,提出预防事故的安全技术和管理建议对策措施,为避免同类事故发生提供理论基础,为密闭储油罐的安生产运行提供技术支撑。

锅炉等离子点火与气化微油点火技术的安全性分析

首先解读了锅炉等离子点火与气化微油点火技术的基本原理和关键组件。接下来,介绍了3种评估手段在点火技术安全性评判中的具体运用。还对设备安全性、操作安全性和环境安全性进行细致分析。最后对安全性分析的整体发现进行了归纳,对两种点火技术的安全性做出客观评价,同时提出针对不同场景的适应性建议以及未来研究路径。

Investigation of extracted Sclerocarya birrea seed oil as a bioenergy resource for compression ignition engines

Sclerocarya birrea(Marula)seed oil was extracted and characterized for its physico-chemical properties and fatty acid compositions,respectively,by using standardized laboratory methods of the Association of Official and Analytical Chemist(AOAC).The fuel and lubrication properties of marula oil were also determined by using the ASTM methods,and the oil was evaluated in terms of its antiwear,viscometrics,volatility,stability,environmental compatibility properties and energy content.It was found that the high percentage of mono-unsaturated oleic acid(73.6%)provided the oiliness that makes marula oil a natural alternative to genetically modify high oleic acid sunflower oil used in biodiesel production.The aggregate properties of seed oiliness as exemplified by the high oleic acid content,high saponification value(178.6 mg/KOH)and viscosity(41 mm2/s)makes marula oil to be prospective based oil for engine crank case biolubricants with antiwear and friction reduction properties.However,the higher oil viscosity exhibited by marula seed oil in comparison to diesel could pose some durability problems to compression ignition engines,when used directly as fuel.Nonetheless,the reduction of oil viscosity would be required by heating,blending with diesel fuel,or by transesterification to forestall the risk of engine failure resulting from the use of unmodified marula oil.The flash point of marula oil(235℃)is somewhat close to that of monograde SAE 40 mineral oil(240℃),and appreciably higher than that of diesel fuel(52℃).The high flash point makes the seed oil less flammable and ensures safer handling and transportation.While,the low pour point(-13.7℃)ensures the oil usability for engines at cold start and under low load conditions.The oxidation stability of marula oil is ascribed to the traces of natural antioxidants presented in the oil and improves the oil’s shelf life,notwithstanding the high peroxide value(4.58 mequiv/kg),and linolenic acid content(0.3%),which ought to have been the culprit for lipolytic hydrolysis and rancidity.Furthermore,marula seed oil is more biodegradable and environmentally friendly than oils derived from petroleum crude.The closely related cetane number(47.8)and heating values(38.2 mJ/kg)of marula oil to diesel fuel would undeniably sustain the combustion efficiency of diesel fuel and also supply a comparable engine performance output in compression ignition engines.The candidacy of marula seed oil,as a bioenergy resource for alternative fuel,fuel additives and lubricants,will no doubt expand the energy supply mix,conserve fossil fuel reserves and mitigate environmental contamination.

等离子无油点火技术的特性及优化措施

当前,等离子无油点火技术具备五大优势,即经济性、环保性、高效性、操作简易性和安全性,可去除燃油输送系统,消除了柴油储存的安全风险。作为一种创新点燃技术,如果能在技术层面上提升锅炉点火的可靠性,既能有效解决能源浪费问题,也能改善锅炉的燃烧环境。基于此,深入探讨了等离子无油点火技术的特点及优化策略。

青龙寺煤矿煤层特征综合研究

为查明陕北侏罗纪煤田新民矿区青龙寺煤矿井田煤层特征,进而为煤炭资源的洗选、加工利用以及煤矿安全、高效、绿色、智能化开采提供基础地质资料,采用地质钻探、岩心精细描述、宏观/显微煤岩组分分析、煤地球化学分析、煤自然发火试验及发火标志性气体气相色谱分析、比热分析等多种技术手段,根据测试结果,综合分析青龙寺煤矿煤岩煤质特征及其自然发火特征。结果表明,新民矿区青龙寺煤矿各煤层裂隙不发育,煤体的坚固性系数1.5~3.2,属于中硬—坚硬煤体,并提出了注水压裂超前弱化坚硬煤岩体、降低煤岩体强度;煤质具有中—高水分、低灰分、低—特低硫、高发热量的高焦油煤的特征,局部存在高水分煤;煤层均属于自燃—容易自燃煤层、自然发火期短,发火标志性气体为CO、C_(2)H_(4)、C_(2)H_(6)和C_(3)H_(8),其中C 2H 2为辅助性标志,5^(-2)煤层最短自然发火期为36 d。煤炭开采过程中,加强对漏风通道的封堵的同时,应加强密闭采空区气体监测、综采工作面通风管理和开采速度的控制,严格落实综合防灭火措施。研究成果可为煤矿煤炭资源清洁利用、加工洗选以及火灾的早期预警和日常防治提供依据。

我国电站锅炉煤粉直接点火技术的发展以及现状

对我国现有的各种煤粉直接点火技术的原理、燃烧器结构以及在我国的发展和应用现状进行了阐述,并指出其各自的优缺点。总结了现有煤粉直接点火燃烧器普遍存在的有关安全性方面的几个问题。为了解决现存电力行业的运行安全性与节油两者矛盾,提出了两类解决手段:其一,采用多种调节手段降低煤粉气流着火热;其二,将直接点火技术与传统点火油枪两者配合使用。指出高温空气直接点火技术因其灵活的调节手段,具有较大的技术优势。

无油点火燃烧器的数值试验研究

该文对冷态高速煤粉气流在电磁感应无油点火燃烧器内的点火过程进行数值模拟,使用概率密度函数(ProbabilityDensity Function)与局部瞬时反应平衡模型模拟气相场的燃烧,采用拉格朗日随机轨道模型模拟颗粒运动轨迹,气相湍流流动采用κ-ε双方程模型,辐射模型采用离散坐标(Discrete-Ordinate)模型。并根据数值试验结果找出不同煤粉浓度对着火温度与着火距离的影响,其结果不但与实验数据较为吻合,而且可以反应出煤粉在无油点火燃烧器内着火方式的变化,对今后的感应式无油点火燃烧器的试验研究以及设计、运行提供理论指导。

煤粉浓度对煤粉高温热壁点火影响的试验研究

为了研究煤粉浓度在热壁无油点火中的影响规律,该文进行了详细的试验研究, 揭示了煤粉气流在高温管壁面加热情况下的着火过程和煤粉浓度对无油点火过程的影响。煤粉的着火过程分为3个阶段:初始的挥发分均相着火段、发展的焦炭多相着火段和最后的燃烧稳定段。煤粉浓度的升高导致了煤粉气流着火推迟,着火距离增加,系统出口温度降低,并促使系统出口烟气组成发生了显著的变化。文中得到的煤粉浓度对煤粉高温热壁面点火的影响规律,对于煤粉高温热壁面无油点火燃烧器的设计和运行提供了重要的理论依据。

石油罐区点火源引燃特征及防控策略研究

对导致石油罐区火灾的点火源进行统计分析,识别典型点火源及引燃物质类别,重点分析静电、雷电、明火、热表面等点火源的引燃特性。从能量、存在部位、引发条件、引燃概率等方面对罐区典型点火源的引燃特性进行定量表征。以实例分析评估了某石油罐区点火源的引燃能力,在此基础上提出针对性的点火源防控策略,降低罐区火灾爆炸事故的发生频率。

自然冷却高燃点油变压器温升计算方法

高燃点油变压器以其优越的防火减灾功能越来越受到用户的青睐。由于高燃点油的热物性与变压器油有很大的不同,粘度远高于变压器油,不能应用现有的变压器温升计算方法来计算高燃点油变压器的温升。文中根据传热学基本原理提出了一套计算高燃点油变压器温升的计算方法,用以计算高燃点油变压器平均油温升、顶油温升、绕阻温升等。计算结果与试验值吻合良好,可以满足工程设计计算需要。这为高燃点油变压器的研制开发提供了一种热设计的新方法。

改进国产汽车燃油加热器点火性能

分析研究了中国生产的汽车燃油加热器中的主流产品因供油系统和点火系统的性能不够完善而导致使用不便和燃烧运行初期排烟过浓、滴油严重等问题 ,并采用两种不同点火塞进行了排放试验。结果表明 ,该试验方法对降低该产品运行初期的排烟和简化开机操作具有明显效果。