四角切圆锅炉富氧燃烧对NO_x生成影响的数值模拟

采用RFG富氧燃烧方法在新疆某电厂350 MW机组锅炉上进行数值模拟,对燃烧时炉内温度场、CO与O2及NOx排放进行分析。结果表明:在21%、25%、29%富氧燃烧工况下,NOx排放浓度均低于空气燃烧时的浓度;四角切圆燃烧煤粉锅炉采用富氧燃烧后,炉膛出口NOx浓度由空气燃烧时的359 mg/m3分别降低到235 mg/m3、272 mg/m3、305 mg/m3;高浓度的CO2与煤粉反应生成CO,形成还原性氛围,有助于抑制NOx生成以及增大对已生成NOx还原的概率;在氧气含量为21%的浓度下,通过增加循环烟气中NO含量可以减少NOx的生成和排放。     

宁夏石沟驿煤气化残炭燃烧特性研究

利用TG/DTA 6300型热分析仪研究了宁夏石沟驿煤的气化残炭的燃烧特性,从着火特性、燃尽特性和稳燃特性三个方面分析了升温速率、粒径和氧气浓度对气化残炭燃烧特性的影响,并采用正交实验分析了升温速率、粒径和氧气浓度三个因素对气化残炭燃烧特性影响的耦合作用.实验结果表明,提高升温速率可以改善气化残炭的燃尽特性;粒径的减小有助于气化残炭的着火;氧气浓度的增加对改善气化残炭燃烧特性有明显的作用,但这种改善效果随氧气浓度的增加而减弱;升温速率对气化残炭的着火特性影响最大,而氧气浓度对气化残炭的燃尽特性和稳燃特性影响最大.     

富氧燃烧系统及其节能效果

提高助燃空气中氧气的浓度,可以获得很好的节能效果,然而过去却没有氧气富化的适当方法。本文介绍了通过“富氧燃烧系统”获得富氧空气而进行高效率燃烧的方法。该套系统应用于陶瓷工业窑炉,节能效果显著,开拓了陶瓷工业节能的新途径,值得陶瓷业界的同志们研讨。 (译者)     

大规模富氧空气燃烧煤(石千)石生产水泥

1 富氧空气燃烧的基本概况众所周知,氧气为助燃物,增加空气中氧浓度能增强燃烧过程热强度。然而,工业上实际应用富氧空气燃烧的过程还不太普遍。目前,主要用于金属冶炼方面。如雷氧炼钢,富氧炼铁,富氧炼铜、铝等。某些企业用富余工业氧气,在空气中渗入,从而提高加热炉热强     

氧气浓度对K2CO3催化无烟煤和石墨燃烧的影响

采用综合热分析仪研究不同氧气浓度下K2CO3催化无烟煤和石墨燃烧的特性,考察了氧气浓度对催化燃烧机制的影响. 结果表明,K2CO3提高了燃烧反应和氧气扩散速率,但对燃烧速率的提高幅度大于对氧气扩散速率提高幅度,延长了无烟煤燃烧过程的平台时间. 氧气浓度由21%增加到100%时, K2CO3催化无烟煤着火温度降低幅度由37.7℃增至78.1℃,催化石墨着火温度降低幅度由204.8℃增至233.6℃. 煤燃烧初期K2CO3使燃烧活化能下降,氧气浓度高于40%时,燃烧由扩散向反应控制转变;燃烧后期活化能低于40 kJ/mol,燃烧受扩散控制. 石墨在燃烧初期K2CO3使燃烧活化能下降,但氧气浓度增加并未改变燃烧控制步骤,燃烧受反应控制;燃烧后期氧气浓度由21%增加到100%时, K2CO3催化石墨燃烧活化能由39 kJ/mol增至110 kJ/mol,燃烧由扩散控制向反应控制转变.     

富氧再生提高催化裂化装置能力

加工重原料油和／或多产汽油都需要炼油厂增加催化裂化装置的加工能力，提高催化裂化装置加工能力或转化率，通常都受到再生器烧焦能力的限制，而再生器的烧焦能力又受到鼓风机最大能力或再生器气体速度的限制。富氧是一种提高燃烧空气中氧含量、可靠、成本低的技术，在控制氮含量增加不突破再生器气体速度允许范围的情况下，可以提高再生器的烧焦能力。富氧通常是把氧气加到鼓风机出口燃烧空气的下游。增加的氧气可以提高再生器的烧焦能力，因此能提高催化裂化装置的加工能力。     

用于燃烧的富氧工艺

利用热天平研究了煤在不同的氧气浓度条件下的燃烧行为,利用中空纤维膜组件进行了氧气富集试验,研究了操作工况对富氧空气通量和氧气浓度的影响。结果表明随着氧气浓度的增加,煤的着火温度及燃烬温度提前,燃烧速度增大,富氧空气的体积分数为30%左右较为合适。用于燃烧的富氧工艺的温度为20 ℃,压力为0.9 MPa,回收率应控制在90%左右。     

作为橡胶替代品的耐热共聚聚酯弹性体

正在轻型车辆消费市场,为满足未来CAFE的要求,汽车OEM厂商采用的策略之一是在更广泛的范围内配置涡轮增压发动机。用增压空气冷却器(CAC)的涡轮增压是当今汽车制造商拥有提高发动机效率的最经济有效的方法。有了涡轮增压,发动机在活塞进气行程吸入相同体积的空气,但由于空气预压缩,可获得更大量的氧气,在燃烧循环中燃烧更多的汽油。这提高了每个燃烧循环产生的功率。通过设计汽缸较少的新型发动机可保证涡轮增压汽车的输出功率,同时减少了油耗和尾气排放。     

富氧燃烧的技改

富氧燃烧过程中因氧气含量增加,燃烧速度加快,燃烧过程得到强化,热辐射迅速增强,燃尽率得到提高,有助于提高热效率。同时空气量及烟气量均显著减少,火焰温度、火焰黑度和辐射热均随着燃烧空气中氧气比例的增加而显著提高,从而达到节能降耗减排、延长窑运行周期等目的。我公司通过对一线熟料生产线进行富氧燃烧改造,提高了回转窑煅烧的稳定性及熟料台时产量,减少了烧成煤耗,降低了熟料生产成本,取得了良好的环境、经济与社会效益。     

蓄热式钢包烘烤过程中包内高温低氧特性的数值模拟

为了分析入炉气体的预热温度对高温空气燃烧过程的影响,综合考虑体系的质量、动量、能量守恒以及燃烧体系的组份平衡,建立了煤气-空气双预热的三维非稳态燃烧数学模型,并以CFX4.3为计算平台,耦合流体流动、燃烧和换热过程,首次对蓄热式燃烧过程中高温低氧特性进行了数值研究,得出了在不同预热温度时,燃烧室内气体温度场和氧气浓度场分布. 结果表明, 提高气体预热温度有利于加快燃烧进程,提高燃烧室内气体的整体温度及温度均匀性,降低局部氧浓度.     

Specific features of combustion in gasoline-driven internal combustion engines

Physical and chemical processes of gasoline combustion in internal combustion engines are considered. A model of combustion evolution in gasoline-driven engines, which explains some specific features of the processes in internal combustion engines, is proposed.     

Large-eddy simulation of turbulent combustion using different combustion models

The second-order moment (SOM) combustion model proposed by the present authors is compared with eddy-break-up (EBU) and presumed probability density function (PDF) combustion models in large-eddy simulation of jet diffusion combustion, swirling diffusion combustion and premixed combustion behind a bluff body. The statistical results for time-averaged and RMS fluctuation temperatures are validated by experimental results. It is seen that the SOM model can always give good statistical results in LES of both non-premixed and premixed combustion, whereas the EBU and presumed PDF models cannot always do. The instantaneous results indicate that organized large vortex and thin flame surface structures are observed in jet diffusion combustion and bluff-body stabilized premixed combustion, whereas no organized vortex and thin flame surface structures are observed in swirling diffusion combustion.     

Tetrazole combustion

Minsk. Translated from Fizika Goreniya i Vzryva, Vol. 24, No. 5. pp. 48–51, September–October, 1988.     

煤粉燃烧室改烧混合煤的技术措施

我厂窑外分解窑和立波尔窑采用烟煤与无烟煤比例为３０％∶７０％的混合煤，这种煤的挥发分为８％～１２％、灰分为２０％～２４％、细度为２％～５％、水分＜３．５％、着火温度约６００℃。３台Φ３．５m×１０m中卸烘干生料磨配套的３个煤粉燃烧室仍然只能烧烟煤，每天２号煤磨（Φ２．２m×４．４m）要为此专门开机４h左右。如果燃烧室也烧混合煤，既可以节省每吨烟煤与无烟煤近９０元的差价，也可以停开２号煤磨。燃烧室所用煤计划与立波尔窑所用混合煤一样，由１号风扫煤磨（Φ２．８m×８m）磨制。本着尽可能节省投资的原则，我们采…     

Influence of combustion aids on suspension combustion synthesis of mullite powders

Mullite powders were obtained by suspension combustion synthesis. The reaction was performed in a combustion reactor designed in the laboratory, which presents some advantages over other classical procedures (heating with a hot-plate, a furnace or a microwave oven). Aluminium nitrate, as a source of Al, and either TEOS or a colloidal silica suspension, as a source of Si, were used as reagents. Urea, at either 100 or 200% excess over the stoichiometric ratio, was used as fuel. NH₄NO₃, HNO₃, NH₄Cl and H₂O₂ were compared as combustion aids. Mullite phase with a high crystallinity and a high specific surface area was directly obtained by using aluminium nitrate, colloidal silica suspension, a 100% excess of urea and either NH₄NO₃ or H₂O₂. The selection of a combustion aid determines the characteristics of the as-synthesized powders. In addition to enthalpy predictions the reduction potential is a key parameter for the combustion to occur.     

Numerical simulation of turbulent gaseous combustion in axially symmetric combustion chambers

A mathematical model and numerical algorithm are developed for the combustion of gaseous fuels in two dimensional turbulent flows. The model includes a system of basic differential conservation equations for the gaseous phase, supplemented by equations for the energy and dissipation rate of turbulent fluctuations for calculating the turbulent diffusion coefficient, as well as a mixing function for initially unmixed flows and its dispersion for describing the effect of turbulence on the concentration of the components, on the temperature, and on chemical reaction rates in terms of a probabilistic approach with a probability density function whose first moment is the mixing function and whose second moment is its dispersion. The calculations are compared with experimental data. The model is found to be effective for thermodynamic equilibrium and for finite kinetics. The results are in satisfactory agreement with the experimental data. Translated fromFizika Goreniya i Vzryva, Vol. 34, No. 4, pp. 3–12, July-August 1998     

玻璃熔窑的全氧燃烧、纯氧助燃和富氧燃烧技术

介绍了玻璃熔窑全氧燃烧技术、纯氧助燃技术和富氧燃烧技术的一些最新研究成果和技术优势,指出全氧、纯氧或富氧燃烧技术是玻璃企业节能降耗、提高产品质量、取得良好经济效益的有效措施,是企业进行节能改造的重要选择。     

Effect of penetration of fuel stream on combustion in supersonic combustion chamber

Moscow. Translated from Fizika Goreniya i Vzryva, Vol. 26, No. 4, pp. 66–68, July–August, 1990.