Experimental and modeling study of lean premixed atmospheric-pressure propane/O2/N2 flames

A better knowledge of the combustion chemistry in very lean flames is required to improve flame stability and control the presence of oxygenated species as final products. In this work, the chemical structure of lean premixed propane-oxygen-nitrogen flames stabilized on a flat flame burner at atmospheric pressure was determined experimentally. The species mole fraction profiles were also computed by the Premix code (Chemkin II version) and three recently proposed mechanisms. Globally, the agreement between measured and computed mole fractions profiles is similar, despite large differences in the number of reactions in each mechanism. Pathways analyses show that only weak variations are observed in the relative importance of the main oxidation routes when the equivalence ratio is decreased from 0.9 to 0.5.     

基于图像识别的二次仿真及在氧化铝回转窑上的应用

提出一种基于图像识别的二次仿真的方法。首先,介绍图像—运行工况—数值仿真结果之间的关系。其次,提出一种二次仿真系统的框架,并详细介绍二次仿真的数学模型、图像识别、聚类等模块。最后,以回转窑火焰图像及回转窑内温度场为对象,实现了系统原型机。通过实际数据进行验证试验,结果表明,该方法能够较准确地给出仿真结果,极大缩短计算时间,从而为回转窑内温度监测提供一种新思路。     

瞬间耐1500℃以上聚氨酯泡沫研制

主要介绍采用在聚酯 多元聚合成中,引入含得核及阻燃基团的结构等方法,使合成的聚氨酯 泡沫在瞬间达到耐１５００℃以上的烧蚀,并具有阻燃自熄及及高的机械强度。     

阻燃剂新品种——微胶囊化TBC及其应用

采用微胶囊包覆的方法提高了三－（２,３－二溴丙基）异氰尿酸酯（ＴＢＣ）的热稳定性,对这种阻断剂新品种的制备方法,性质和用途做了介绍。     

Activated soil filters (bio filters) for the elimination of xenobiotics (micro-pollutants) from storm- and waste waters

A technical scale (0.12 m³) activated soil filter (bio filter) has been used to eliminate diverse xenobiotics (organic micro-pollutants) such as organophosphate flame retardants, and -plasticisers, musk fragrances, DEHP, benzothiazoles and triclosan from water. Model experiments to treat combined sewer overflow, storm water and a post treatment of waste water were performed in controlled laboratory experiments. The indicator compounds were typical for waste water. Diverse chemical compound groups and a wide spectrum from the lipophilic (pK_ow = 5.9) to the hydrophilic (pK_ow = 2.6) were included. The system consisted of a layer with high organic content (with vegetation to prevent clogging), a sand filter and a gravel drainage layer. The organic layer was spiked with activated sludge to enhance biomass and biodegradation potential. Usually the elimination rates varied from 64% to 99%, with only one compound reaching as little as 17%. For a technical suitability assessment it was calculated how long these filters would be stable in eliminating organic compounds from water. The estimated operating times for such systems was found to be about 100 years for a stack height of 2 m a year in regard to most compounds in this study.     

Sensitivity to change in laminar burning velocity and Markstein length resulting from variable hydrogen fraction in blast furnace gas for changing ambient conditions

The sensitivity to changes in fuel characteristics has been investigated for combustion of Blast Furnace Gas resulting from small volumetric increases in H₂ concentration. A nonlinear methodology has been employed to quantify unstretched flame speeds and the effect of flame stretch from outwardly propagating spherical flames. Following benchmarking work with CH₄, results were obtained under ambient conditions of 303 K and 0.1 MPa, with small absolute change in hydrogen concentration shown to at least triple the laminar burning velocity for all tested mixtures. Fuel composition and equivalence ratio were shown to independently influence mixture diffusivity and Lewis number, quantified by change in the obtained values of Markstein length. Temperature and pressure were increased to respective values of 393 K and 0.2 MPa to investigate influence of ambient conditions, with a power law correlation presented. Finally the performance of several published chemical reaction mechanisms has been evaluated through comparison of 1-D flame models.     

Nonlinear thermoacoustics of ducted premixed flames: The influence of perturbation convection speed

When a premixed flame is placed within a duct, acoustic waves induce velocity perturbations at the flame’s base. These travel down the flame, distorting its surface and modulating its heat release. This can induce self-sustained thermoacoustic oscillations. Although the phase speed of these perturbations is often assumed to equal the mean flow speed, experiments conducted in other studies and Direct Numerical Simulation (DNS) conducted in this study show that it varies with the acoustic frequency. In this paper, we examine how these variations affect the nonlinear thermoacoustic behaviour. We model the heat release with a nonlinear kinematic G-equation, in which the velocity perturbation is modelled on DNS results. The acoustics are governed by linearised momentum and energy equations. We calculate the flame describing function (FDF) using harmonic forcing at several frequencies and amplitudes. Then we calculate thermoacoustic limit cycles and explain their existence and stability by examining the amplitude-dependence of the gain and phase of the FDF. We find that, when the phase speed equals the mean flow speed, the system has only one stable state. When the phase speed does not equal the mean flow speed, however, the system supports multiple limit cycles because the phase of the FDF changes significantly with oscillation amplitude. This shows that the phase speed of velocity perturbations has a strong influence on the nonlinear thermoacoustic behaviour of ducted premixed flames.     

Hydrogen addition effects in a confined swirl-stabilized methane-air flame

The effect of hydrogen addition in methane-air premixed flames has been examined from a swirl-stabilized combustor under confined conditions. The effect of hydrogen addition in methane-air flame has been examined over a range of conditions using a laboratory-scale premixed combustor operated at 5.81 kW. Different swirlers have been investigated to identify the role of swirl strength to the incoming mixture. The flame stability was examined for the effect of amount of hydrogen addition, combustion air flow rates and swirl strengths. This was carried out by comparing adiabatic flame temperatures at the lean flame limit. The combustion characteristics of hydrogen-enriched methane flames at constant heat load but different swirl strengths have been examined using particle image velocimetry (PIV), micro-thermocouples and OH chemiluminescence diagnostics that provided information on velocity, thermal field, and combustion generated OH species concentration in the flame, respectively. Gas analyzer was used to obtain NO_x and CO concentration at the combustor exit. The results show that the lean stability limit is extended by hydrogen addition. The stability limit can reduce at higher swirl intensity to the fuel-air mixture operating at lower adiabatic flame temperatures. The addition of hydrogen increases the NO_x emission; however, this effect can be reduced by increasing either the excess air or swirl intensity. The emissions of NO_x and CO from the premixed flame were also compared with a diffusion flame type combustor. The NO_x emissions of hydrogen-enriched methane premixed flame were found to be lower than the corresponding diffusion flame under same operating conditions for the fuel-lean case.     

建筑塑料的阻燃和抑烟

本文论述建筑塑料的燃烧过程、阻燃和成烟机理．提出了阻燃和抑烟的技术措施．     

琼脂中微量元素的测定--非完全消化-火焰原子吸收法

用非完全消化法处理琼脂样品,即先用浓硝酸消解样品,再用乳化剂TritonX-100溶解消解产物而配制成一均匀透明的样品溶液。建立了非完全消化-火焰原子吸收法测定琼脂中钙、镁、铁、锌的新方法。以La3+作为钙、镁的释放剂消除样品中共存元素的干扰。试验表明,试液的粘度与其空白溶液的一致。对样品处理条件、背景吸收干扰、检出限及特征浓度进行了考察。质量浓度的线性范围(mg/L)为:钙0～14,镁0～0.8,铁0～7,锌0～1。测定结果的相对标准偏差不大于2.2%,测定结果与灰化法一致,相对误差小于±2.3%。可见,在火焰原子吸收光谱法中,以非完全消化法取代灰化法处理琼脂样品是可行的。