Mechanism of particulate reduction in heavy fuel oil combustion

A residual fuel oil, neat and with four different additives, was tested using three experimental devices: a very fast pyrolyser of fuel droplets which produced cenospheres; a thermogravimetric analyser which gave information on the reactivity of the cenospheres; and a 1.16 MW boiler. The additives did not modify cenosphere production in the pyrolyser, but changed their reactivity. This reactivity change was in accordance with particulate reduction in the boiler and with the retention of the metal additive in the cenospheres. The retention of the metal depended on the nature of the organic part of the additive.     

循环流化床燃烧在高过剩空气下的NOx排放

提出了借助循环流化床在高过剩空气系数下燃烧的技术提供高温空气的新构思。搭建了循环流化床燃烧热态试验台,完成了循环流化床燃烧在高过剩空气系数下的NOx排放特性试验,结果表明:循环流化床在高过剩空气系数下燃烧温度分布均匀,燃烧稳定性好;过剩空气系数增大,氮氧化物排放增加;提升管二次风高度的增加和还原区系数的减小有利于控制氮氧化物的排放水平和减少煤中的N向NOx的转化比。在过剩空气系数为1.6、还原区系数为0.72和二次风高度为1 500 mm时,循环流化床NOx排放为339 mg/m3,煤中的N向NOx转化比为21%。循环流化床高温空气NOx的浓度对燃料高温燃烧NOx排放的影响需要进一步研究。     

Effect of fuel composition on NOx formation in high‐pressure syngas/air combustion

In this study, an experimental investigation of lean premixed syngas/air flames with H₂/CO ratio of 1.0 and equivalence ratio of 0.5 has been conducted in a high‐pressure burner facility to investigate the effects of pressure and the presence of hydrocarbons on NO_x speciation. Detailed NO_x speciation measurements in the post‐flame region were conducted for various pressures up to 1.5 MPa (15 bar) using Fourier transform infrared (FTIR) spectroscopy. When the pressure is increased, NO concentration decreases while NO₂ increases due to pressure dependence of NO to NO₂ conversion. For a given pressure, the presence of hydrocarbons in syngas leads to an increase in NO_x concentrations possibly due to prompt NO formation. Comparison of NO concentrations in presence of CH₄ at different pressures shows that the effect of CH₄ due to prompt NO formation is more dominant than the effect of pressure on NO. © 2018 American Institute of Chemical Engineers AIChE J, 64: 3134–3140, 2018     

采用高硫重油为燃料生产抗硫酸盐水泥的 设计对策

伊拉克原油中的全硫平均含量在4.5%以上,对采用重油为燃料的水泥生产影响较大。伊拉克AL-Douh水泥厂303000t/d熟料水泥生产线项目采用了高硫重油为燃料,文章介绍了其针对高硫重油为燃料所采取的设计对策,结合该项目投产后的实际生产数据,对水泥窑采用高硫燃料生产抗硫酸盐水泥(SRC)的技术控制措施作进一步分析和设计计算。该线从投产至今,运行状况良好。     

An experimental study on high temperature and low oxygen air combustion

High temperature preheated and diluted air combustion has been confirmed as the technology, mainly applied to industrial furnaces and kilns, for realizing higher thermal efficiency and lower emissions. The purpose of this study was to investigate fundamental aspects of the above-mentioned combustion experimentally and to compare with those in ordinary hydrocarbon combustion with room temperature air. The test items were exhaust gas components of CO, NO_x, flame shape and radical components of CH, OH and C₂, which we measured with gas analyser, camera and ICCD (Intensified Charged-Coupled Device) camera. Many phenomena, as a result, which appeared in the combustion with the oxidizer, low oxygen concentration and extremely high temperature air, such as expansion of the flammable limits, increased flame propagation speed, looked very strange in comparison with those in existing combustion technology. We confirmed that such extraordinary phenomena were believable through a hot-test experiment.     

高温空气燃烧技术在隧道窑中的应用分析

高温空气燃烧技术(HTAC)是一种具有节能和环保等多重优点的新型燃烧技术,已在钢铁工业(加热炉)和玻璃工业(熔窑)得到了成功应用。结合HTAC技术的优势和耐火材料工业隧道窑的特点,分析了该技术在隧道窑应用的可行性,提出了技术方案,并对已有实践方案进行了总结和补充。     

改善蒸汽驱效果的高温泡沫剂研究

利用自主研发的泡沫剂GFPJ,通过引入不同类型的高温泡沫稳定剂,得到能够满足稠油蒸汽驱要求的高温泡沫剂体系。对不同高温泡沫剂体系的发泡性能、耐高温性能以及高温封堵性能进行了研究。通过对不同高温泡沫剂体系老化前后有效含量的变化测定,表明了高温泡沫稳定剂的主要作用是能够降低泡沫剂的降解速率,从而提高泡沫剂体系的耐高温性能。     

超临界对冲旋流燃烧锅炉低氮改造

为了降低进入SCR(选择性催化还原)装置的NO_x浓度,拟对某电厂600 MW超临界锅炉进行低氮燃烧器改造,在改造前对NO_x排放浓度高的原因进行分析,同时提出3种备选改造方案并进行数值模拟研究,最后确定最优方案,即:保持原来燃烧器数量、位置不变,减小各次风的通流面积(风速不变),使主燃烧器区域过量空气系数为0.85,更换先进的低氮燃烧器,在原来的位于34.724 m标高位置的16只SOFA(分离燃尽风)风口中只保留两侧墙的6只,并在标高39.350 m处布置一层SOFA燃尽风(12个喷口)。改造后进入SCR的NO_x平均质量浓度约为400.7 mg/m~3,与数值模拟计算结果误差为12.8%,说明数值模拟计算结果具有参考意义。     

用重残油配制燃料油的研究

利用重残油替代部分蒽油,与沥青配制成合格的燃料油,既扩大了沥青的销路,又降低了配制燃料油的成本。研究过程分为实验室小试与生产中试两部分,通过小试得到最佳配比,中试产品的指标全部符合要求。     

Analysis of low NO emission in high temperature air combustion for pulverized coal

High temperature air combustion experiments for pulverized coal in a large-scale furnace have been done before and shown that the NO emission in the high temperature air combustion is significantly lower than that in the normal temperature air combustion. This paper numerically studies the NO evolution in the large-scale experiments with a simplified chemical reaction model. Through an analysis of numerical results a low NO emission mechanism in the high temperature air combustion has been presented. If the HCN concentration is high, the NO generation is fast. But, the high HCN and NO concentrations together will make NO destruction fast. It is found that, by properly arranging flow patterns, the high HCN and NO concentrations can be obtained in the vicinity of primary air nozzle. Thus, the generation and destruction of NO can reach an equilibrium point so that the net NO emission rate is low.     

空气氧化燃料油脱硫技术研究进展

空气氧化脱硫技术因其反应条件温和、不使用昂贵的氢气、投资和操作费用低等优点日益受到重视.目前研究的氧化脱硫技术大多采用H2O2作氧化剂,但H2O2存在价格昂贵、不能再生以及含硫废水排放等问题.采用廉价的空气作氧化剂的氧化脱硫技术可以克服H2O2作氧化剂存在的一些缺点,因此,受到广泛关注.介绍了空气在不同催化体系中氧化燃...     

Low temperature thermal degradation of cellulosic insulating paper in air and transformer oil

The thermal degradation of cellulose in the form of Kraft insulating paper has been studied in air for up to 140 h and in transformer oil for up to 3500 h in the temperature range 60–120 °C using measurements of the degree of polymerization (DP) and (in oil) analysis of furanic degradation products. Degradation was faster in air than in oil. The DP decreased from the original value of 1.2 × 10³ to a limiting value in the range of 300–900 depending on temperature and degradation conditions. The variation of the DP with degradation time was consistent with two mechanisms, one in which the first‐order rate constant decreased exponentially with time, and another in which only a limited number of chain bonds were scissionable. The degradation rate was first order in scissionable bonds. The major furanic degradation products were 2‐furaldehyde, 5‐hydroxymethyl‐2‐furaldehyde and furfuryl alcohol. Their concentrations continually increased over the timescale of the experiments. © 2001 Society of Chemical Industry     

Low temperature exhaust gas fuel reforming of diesel fuel

The application of exhaust gas assisted fuel reforming in diesel engines has been investigated. The process involves hydrogen generation by direct catalytic interaction of diesel fuel with engine exhaust gas. Using a laboratory reforming mini reactor incorporated in the exhaust system of a diesel engine, up to 16% hydrogen in the reactor product gas was achieved at a reactor inlet temperature of 290 °C. The results showed that such levels of hydrogen can be produced with appropriate control of the reaction parameters at temperatures typical of exhaust gas temperatures of diesel engines operating at part load without any requirement for external heat source or air and steam supply. The use of simulated reformed fuel was shown to be beneficial in terms of engine exhaust emissions and resulted in reduction of NO_X and smoke emissions.     

利用富氧加强重油燃烧技改方案探讨

1方案 利用氮站制氮产生的富氧供给窑头加强重油燃烧是节约能源、降低成本的有效途径.将氮站产生的富氧通过助燃风机送入窑内和将富氧在间隙砖位置直接送入窑内,这两种方式在实践中证明是不可取的.将富氧通过空压机以雾化气形式送入窑内这种方式是可行的.     

In-situ combustion laboratory studies of Turkish heavy oil reservoirs

The purpose of this research was to perform dry and wet forward combustion experiments for Turkish heavy oil reservoirs (Raman, Adıyaman and Çamurlu and Batı Kozluca) under different experimental conditions. In the experiments, a vertical tube was packed with crushed limestone and saturated with crude oil and water. It was observed that peak temperatures were higher when stabilized combustion was achieved and decreased as the combustion front approached the outlet end of the tube. In wet combustion experiments, the rate of combustion reaction and therefore rate of heat generation were reduced with the resultant drop in peak temperatures. In dry and wet combustion experiments, excess carbon-dioxide productions were observed due to the decomposition of carbonate minerals. Atomic H/C ratio of the fuel consumed decreased as the average peak temperature increased. Fuel consumption rate was higher for dry combustion experiments as the °API gravity of the crude oils increased. A decrease is also observed in fuel consumption rate after the water–air ratio value is reached to optimum value. For high water–air ratio in wet combustion experiments, a general decrease was observed as the °API gravity of the crude oils increased.     

Autoignition and combustion of water-fuel emulsion during its injection into heated air. III. Completeness of combustion of fuel oil M-40

The dependence of the completeness of combustion of liquid fuel during its pulsed injection into heated air on the parameters of the medium and delivery conditions was established experimentally and it is shown that emulsification of the fuel does not affect the integral completeness of combustion. Therefore, an increase of fuel economy of diesel engines on converting them to a water-fuel emulsion can be achieved only due to a favorable change in the dynamics of the cycle. Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences, Novosibirsk. Translated from Fizika Goreniya i Vzryva, Vol. 31, No. 5, pp. 3–11, September–October, 1995.     

Behaviour of heavy metals in the partial oxidation of heavy fuel oil

The behaviour of heavy metals in the partial oxidation of heavy fuel oils under a pressure of up to 100 bar (10 MPa) has been investigated. The tests were carried out in a 5 MW HP POX (High Pressure Partial Oxidation) test plant, that is operated by the IEC (Department of Energy Process Engineering and Chemical Engineering, TU Bergakademie Freiberg) in cooperation with Lurgi GmbH. In several test campaigns preheated oil with a viscosity of up to 300 cSt (= 300 mm²/s) at the burner inlet has been gasified. The heavy metals nickel Ni, iron Fe and vanadium V occur in heavy residual oils in considerable concentration and may seriously impact the gasification itself and the synthesis gas conditioning and usage. While iron is largely recovered in the gasification residue, the recovery rates of nickel and vanadium depend on the process conditions. Volatile nickel compounds were detected in the raw synthesis gas. It was found that an incomplete carbon conversion enables the capture of nickel Ni and vanadium V in the solid residue phase and can thus mitigate the problem of volatile metal compounds in the raw synthesis gas.     

Production of biodiesel fuel from tall oil fatty acids via high temperature methanol reaction

Tall oil fatty acids are a byproduct of the paper industry and consist predominantly of free-fatty acids (FFAs). Although this feedstock is ideal for biodiesel production, there has been relatively little study of its conversion to biodiesel. Thus, the purpose of this study was to investigate the high temperature reaction of methanol with tall oil at subcritical and supercritical pressures to produce fatty acid methyl esters. This study investigates the effects of mixing, pressure, temperature, and methanol to oil molecular ratio in order to determine the potential use of tall oil as a biodiesel feedstock. In this work, tall oil fatty acids were successfully reacted with supercritical and subcritical methanol in a continuous tubular reactor, resulting in a reaction that is primarily temperature dependent. Conversions at subcritical pressures of 4.2 MPa and 6.6 MPa were 81% and 75%, respectively. Pressure seemed to have little correlation to conversion in both regimes, and conversions were comparable between the two. Additionally, it was found that tall oil fatty acids react well with methanol to give comparable conversions at the relatively low molecular flow ratio of 5:1 methanol to tall oil. Both of these observations suggest that hydrolyzed triglycerides or free fatty acid feedstocks would make the primary high temperature biodiesel reaction and the subsequent separation and purification operations less expensive than was previously believed.     

渤海特稠油高温驱油剂的研制与性能评价

针对渤海D油田原油黏度大,胶质、沥青质含量高,地层水矿化度高且钙镁离子含量高的特点,合成了一种可满足渤海特稠油热采过程中伴注用的高温驱油剂OD-2,并对该驱油剂的界面张力、耐温性能、润湿性能、吸附性能、对油水相对渗透率的影响和驱油效率进行了研究。结果表明:高温驱油剂OD-2耐温可达320℃,对渤海特稠油的界面张力为2.84×10~(-3) mN/m;高温驱油剂使润湿指数从-0.984上升至-0.204;80℃下静态吸附量3.061 mg/g,随着高温驱油剂OD-2质量分数增加,岩心残余油饱和度降低。室内微观驱油结果表明:高温驱油剂提高了注入流体的波及面积和洗油效率。质量分数1.0%的高温驱油剂OD-2在240℃辅助热水驱的驱油效率为79.60%,比单纯热水驱驱油效率提高4.24个百分点。