温度对脱硫剂钙利用率和蒸汽活化效果的影响

在中温烟气脱硫过程中,蒸汽活化对于提高脱硫剂的钙利用率和脱硫效率起到了显著的作用。为了确定温度对于蒸汽活化效果的影响,研究了200～800℃的蒸汽温度范围内钙利用率的变化,给出了合适的蒸汽活化温度。进而分别在400、600、800℃条件下研究了脱硫反应温度与蒸汽活化温度的关系,提出了中温循环流化床烟气脱硫的适用温度范围。     

蒸汽活化对钙基脱硫剂孔结构及固硫能力影响的实验研究

本文用实验方法研究了在电站锅炉排烟温度条件下，水蒸汽对钙基脱硫剂的活化作用．实验结果表明，蒸汽活化使得脱硫剂孔结构发生了显著变化并明显改善了脱硫剂的固硫能力．这为进一步了解活化机理及开发省水，经济的排烟脱硫技术提供了依据．     

用于中温烟气脱硫的新型钙基脱硫剂

研究了高效钙基脱硫剂的制备原理,在石灰水合反应生成氢氧化钙和提高比表面积两个关键环节上,采用了一系列方法提高钙利用率,获得突破性进展。进一步研究了中温范围内脱硫温度对钙利用率的影响,得到700℃时超过95％的钙利用率,为发展中温干式烟气脱硫工艺开辟了新的道路。     

中温烟气脱硫过程中CO2对脱硫剂钙利用率的影响

本文在300～600℃的中温区段,实验研究了CO2在烟气脱硫过程中与钙基脱硫剂发生碳酸盐还原反应,削弱脱硫效果的规律,发现石灰钙利用率随温度升高呈跳跃式变化,并因碳酸盐反应程度的迅速增加而在500℃附近出现低谷.由此明确了减小碳酸盐反应效应,提高脱硫剂钙利用率的途径,为进一步发展中温烟气脱硫工艺提供了重要依据.     

增湿活化反应器内喷水脱硫试验研究

本文介绍在热态脱硫试验台上进行的生石灰和消石灰的喷水活化脱硫试验,研究了Ca/S比、饱和温距、入口烟气SO2浓度、烟气速度及水喷嘴雾化风对脱硫效率和钙利用率的影响规律,对两种脱硫剂的脱硫活性进行了比较,并对喷水增湿提高脱硫效率的机理进行了分析。研究表明,喷水增湿使两种脱硫剂的活性都有明显提高,生石灰具有价格优势。     

蒸汽活化钙基吸收剂用于干法烟气脱硫的实验研究

本文简化模拟实验了燃煤锅炉省煤器后的干法烟气脱硫方案．在沉降炉上实验研究了蒸汽活化对钙基吸收剂脱硫（４００～８００℃）效果的影响．结果表明,蒸汽活化能显著改善钙基吸收剂的微孔结构,提高其转化率．在４００到６００℃下反应产物以亚硫酸钙为主,７００到８００℃反应产物以硫酸钙为主。     

镁渣脱硫剂孔隙结构分形特性的研究

本文在实验室条件下通过镁渣和粉煤灰的水合反应,制备了可用于循环流化床锅炉的脱硫剂。采用热重分析法测定了脱硫剂的钙转化率,借助N2吸附法研究了不同水合条件下脱硫剂孔结构分形维数的变化特性以及分形特性对脱硫能力的影响。结果表明,镁渣孔结构的分形维数会随孔隙平均孔径的增大而减小,也会随水合温度和灰钙比的增大而增大,但在水合时间为8 h时呈现峰值特征;在最佳水合参数下,得到分形维数适中的镁渣脱硫剂,从而达到较好的脱硫效果。     

CO_2辅助SAGD技术流动与传热过程的数值模拟研究

本文为模拟非凝析气CO_2辅助SAGD稠油开采技术,建立了考虑相变的多相多组分流体在多孔介质中的非稳态热平衡模型。通过模型计算,分析并研究了CO_2辅助SAGD稠油热采技术的基本原理及对开采效果的影响。结果表明,CO_2在伴随蒸汽注入后聚集在蒸汽腔的外侧,阻碍蒸汽腔的横向扩展,当非凝析气抵达盖层后,会在中轴线两侧形成非凝析气体富集区,阻碍了蒸汽腔在盖层下方的铺展,减少了蒸汽与盖层的接触面积,从而降低了蒸汽的散热损失,提高蒸汽的利用率。另外,竖直方向的渗透率会影响蒸汽腔的扩展及温度的分布。     

含CO_2的蒸汽凝结换热实验研究

钙基吸收剂锻烧碳酸化循环法能够有效地控制CO2的排放,其中CaCO3的煅烧过程中加入适量水蒸气能够降低煅烧温度,节约成本,对尾气进行冷凝处理能够得到相对浓度较高的CO2,研究了含CO2的蒸汽在水平圆管上的凝结换热特性,从气相边界层与液膜变化的角度对实验结果做出了解释,并总结了凝结换热经验公式。     

新型复合吸附剂传质特性的正交试验研究

为克服复合吸附剂传热与传质性能协同强化的矛盾,本文以膨胀石墨、木粉和氯化钙为原料混合浸渍并固化,形成膨胀石墨为骨架的导热网络,基于氯化钙对木粉的活化造孔形成丰富孔隙的传质通道,获得导热传质良好的复合吸附剂制备工艺。利用正交试验法分析了钙墨比、木粉粒度、钙木比、炭化活化的温度和时间五因素不同水平对渗透特性的影响。结果表明,渗透率在钙木比和木粉粒度上均存在最优值,并随着钙墨比、炭化活化的温度和时间三因素的上升而增大,其中钙墨比对渗透率影响远大于其余因素。经过补充试验验证,最终所获最优样品渗透率达到5.67824×10~(-13)m~2,优化所得制备工艺为钙木比2,温度600℃,时间2.5 h,粒度目数140~150,钙墨比4。     

Methane steam reforming in an annular microchannel with Rh/Al2O3 catalyst

Regularities of methane conversion in the presence of water steam were obtained experimentally while activating chemical conversions on the inner convex wall of an annular microchannel. The steam methane reforming was done on the Rh/Al₂O₃ nanocatalyst with the heat applied through the microchannel gap from the outer wall. Concentrations of the products of chemical reactions in the outlet gas mixture are measured at different temperatures of the outer microchannel wall. The range of channel wall temperatures at which the ratio of hydrogen and carbon oxide in the outlet mixture grows substantially is determined. Data on the composition of methane conversion products for the ratio H₂O/CH₄ = 1.77 and the activation energy of methane steam reforming at reactor outer wall temperatures of up to 880°C are obtained. The effect of the radiation heat exchange and the external diffuse limitation on the rate of chemical conversions in methane steam reforming in an annular microchannel with external heat supply is determined.     

碳制氢过程的比较及直接制氢分析

本文对不同碳制氢过程进行了热力学分析,比较了相同进料条件下,采用不同过程进行碳制氢时,过程的冷煤气效率以及最终产物组成,并分析了“一步制氢”中温度、压力、不同进料比对最终产物组成的影响。结果表明,直接制氧适宜的气化温度为923-973 K;增加水蒸气分压力(气化压力随之增加),气体产物的量增加;吸收剂有一最佳的量。     

Hydrogen production by methanol steam reforming in an annular microchannel on a Cu-ZnO catalyst

Steam reforming of methanol into a hydrogen-containing gas under activated methanol conversion on annular microchannel walls was experimentally investigated. The methanol conversion was carried out on a copper-zinc catalyst deposited on the channel internal wall. The concentrations of the chemical conversion products in the output gas mixture were determined at different reactor temperatures and residence times. The channel wall temperature range within which the methanol steam reforming is intensified was also determined. It was shown that the CO content in the reaction products is determined by the CO₂ partial pressure rather than by the reactor temperature. A kinetic model of methanol steam reforming on a copper-zinc catalyst was developed.     

The combined effect of H2O and SO2 on CO2 uptake and sorbent attrition during fluidised bed calcium looping

The effect of steam and sulphur dioxide on CO₂ capture by limestone during calcium looping was studied in a novel lab-scale twin fluidised bed device (Twin Beds – TB). The apparatus consists of two interconnected batch fluidised bed reactors which are connected to each other by a duct permitting a rapid and complete pneumatic transport of the sorbent (limestone) between the reactors. Tests were carried out under typical calcium looping operating conditions with or without the presence of H₂O and/or SO₂ during the carbonation stage. Carbonation was carried out at 650°C in presence of 15% CO₂, 10% steam (when present) and by investigating two SO₂ levels, representative of either raw (1500?ppm) or pre-desulphurised (75?ppm) typical flue gas derived from coal combustion. The sorbent used was a reactive German limestone. Its performance was evaluated in terms of CO₂ capture capacity, sulphur uptake, attrition and fragmentation. Results demonstrated the beneficial effect of H₂O and the detrimental effect of SO₂ on the CO₂ capture capacity. When both species were simultaneously present in the gas, steam was still able to enhance the CO₂ capture capacity even outweighing the negative effect of SO₂ at low SO₂ concentrations. A clear relationship between degrees of Ca carbonation and sulphation was observed. As regards the mechanical properties of the sorbent, both H₂O and SO₂ hardened the particle surface inducing a decrease of the measured attrition rate, that was indeed always very low. Conversely, the fragmentation tendency increased in presence of H₂O and SO₂ most likely due to the augmented internal stresses within the particles. Clear bimodal particle size distributions for in-bed sorbent fragments were observed. Microstructural scanning electron microscope and porosimetric characterisations aided in explaining the observed trends.     

The study of dehumidifying of carbon monoxide and ammonia adsorption by Iranian natural clinoptilolite zeolite

The natural zeolite (clinoptilolite type) was obtained from the Neibagh region of Mianeh, the city in the west of Iran. The raw zeolite was tested for quality and quantity measurements including surface area and volumetric characteristics as well as thermogravimetry analysis. The acid activation process was used to increase the adsorption rate of zeolite and in order to obtain the optimum conditions: the effect of acid concentration, reaction time and the temperature were studied. A surface area measurement test was performed in each stage to get the best results. Thus, efficient condition was selected according to the produced highest surface area. The reaction was first obtained with hydrochloric acid, and then a comparison was made using the sulfuric acid. The hydrochloric reaction proved to be better. The result of activation was 2.5 times the increase in the surface area in relation to the raw sample. The result of elemental analysis conducted once again on the activated sample showed an increase in the ratio of Si/Al (approximately 0.6). Then, using CO, NH₃ and steam, the gas adsorption capacity of both the raw and activated samples was measured and compared. Since CO was not adsorbed at ambient temperature, but steam was adsorbed relatively well, the natural clinoptilolite zeolite of Iran was suggested as a suitable material for adsorbing humidity form carbon monoxide as well as synthesis gas (H₂ and CO mixture).     

Discovery of temperature-dependent phenomena of muon-catalyzed fusion in solid deuterium and tritium mixtures

A systematic experimental study on muon-catalyzed fusion was conducted using a series of solid deuterium and tritium mixtures. A variety of conditions were investigated, i.e., tritium concentrations from 20% to 70%, and temperatures from 5 to 16 K. With decreasing temperature, we observed an unexpected decrease in the muon cycling rate (lambda(c)) and an increase in the muon loss probability (W). The origins of these observed changes were interpreted by the temperature-dependence in the dt mu formation process for lambda(c) and that in the muon reactivation process after muon-to-alpha sticking for W.     

自然循环蒸汽发生器倒U型管内流动不稳定性判别准则

针对自然循环蒸汽发生器倒U型管内流动不稳定的特点,利用无量纲分析方法建立管内流体控制方程.采用小扰动分析方法,得到倒U型管内流动不稳定的判别准则.通过对某型蒸汽发生器进行计算分析,获得判别准则随流体进口温度和弯管半径变化规律.计算结果表明:随着流体进口温度的升高,特征雷诺数增加,但是不同流体进口温度条件下特征雷诺数随弯管半径的变化规律不同.相对于流体进口温度,弯管半径对特征雷诺数的影响较小.所得结论为蒸汽发生器倒U型管内倒流管空间分布及倒流流量计算提供理论依据.     

Effect of gasification reactions on biomass char conversion under pulverized fuel combustion conditions

The effect of gasification reactions on biomass char conversion under pulverized fuel combustion conditions was studied by single particle experiments and modelling. Experiments of pine and beech wood char conversion were carried out in a single particle combustor under conditions of 1473-1723 K, 0.0-10.5% O₂, and 25-42% H₂O. A comprehensive progressive char conversion model, including heterogeneous reactions (char oxidation and char gasification with CO₂ and H₂O), homogeneous reactions (CO oxidation, water-gas shift reaction, and H₂ oxidation) in the particle boundary layer, particle shrinkage, and external and internal heat and mass transfer, was developed. The modelling results are in good agreement with both experimental char conversion time and particle size evolution in the presence of oxygen, while larger deviations are found for the gasification experiments. The modelling results show that the char oxidation is limited by mass transfer, while the char gasification is controlled by both mass transfer and gasification kinetics at the investigated conditions. A sensitivity analysis shows that the CO oxidation in the boundary layer and the gasification kinetics influence significantly the char conversion time, while the water-gas shift reaction and H₂ oxidation have only a small effect. Analysis of the sensitive parameters on the char conversion process under a typical pulverized biomass combustion condition (4% O₂, 13% CO₂, 13% H₂O), shows that the char gasification reactions contribute significantly to char conversion, especially for millimeter-sized biomass char particles at high temperatures.     

催化着火的实验研究

本文就CH4-水蒸气以及正庚烷或正十二烷-水蒸气的催化重整反应对燃料与空气预混气的着大影响进行了几种不同工况的实验研究,并与纯燃料气（CH4气、正庚烷或正十二烷蒸气）和空气的预混气的着火进行对比．实验结果表明,在催化剂的作用下,烃类燃料气和水蒸气能在200～500℃的较低温度下进行重整反应,产生部分H2和CO。少量H2的存在大大降低了预混气的着火温度。若将这种催化剂用于柴油机汽缸壁,则可望使柴油机中的乳化油在汽缸壁上生成部分H2,因此可能在掺水量加大的条件下,仍然能实现汽缸中的正常燃烧,这不仅使乳化油在柴油机中的应用成为可能,而且将显著地改善柴油机的排放性能和节能效果．     

用NiCuZnAl催化剂最大化生物油自热水蒸汽重整制氢

在较低的温度下,通过将放热的部分氧化反应和吸热的水蒸汽重整反应耦合起来的自热方式实现了高效的制氢过程. 在氧碳比(O/C)为0.34,水碳比(S/C)为3,温度为600 oC时生物油接近完全转化,得到最高氢产率为64.3%. 自热水蒸汽重整反应条件温度、O/C、S/C、质量空速等可以用来控制反应氢产率和气体产物分布. 对自热过程和普通水蒸汽重整过程做了比较,并对反应机理进行了探讨.