N2和CO2惰化丙烯爆炸极限参数实验研究

为得到惰化条件下丙烯的爆炸极限参数的变化规律，采用标准的可燃性气体爆炸极限测试装置(GB/T 12474—2008)，测试研究了N₂和CO₂对丙烯的爆炸极限、临界氧浓度和最小氧浓度的影响，并绘制了C₃H₆-N₂/CO₂-Air爆炸三角形图，对比分析了N₂和CO₂对丙烯爆炸极限参数的惰化效果。结果表明，添加N₂和CO₂都会缩小丙烯爆炸极限范围，减小爆炸的危险度。N₂惰化条件下，丙烯爆炸上下限重合时N₂添加量为49%，临界氧浓度为9.79%；在CO₂惰化条件下，丙烯爆炸上下限重合时，CO₂的添加量为34%，临界氧浓度为12.94%。在丙烯浓度不变的情况下，发现CO₂惰化氛围下的最小氧浓度值均高于N₂惰化条件下的。两种惰化工况下的丙烯爆炸三角形结果显示，在CO₂惰化的爆炸区域明显小于N₂惰化下的；当添加惰性气体使丙烯处于完全惰化状态时，CO₂的窒息比和添加量均小于N₂。本文的实验数据及结论可为进一步研究丙烯爆炸和工业丙烯安全防爆工作提供理论基础。     

C2H6/C3H8影响CH4爆炸极限参数及动力学特性研究

为研究C₂H₆/C₃H₈对甲烷爆炸极限参数及动力学特性的影响,采用标准的可燃气体爆炸极限测定装置测定了不同配比的C₂H₆/C₃H₈混合气体对甲烷爆炸极限的影响规律,同时得出了氮气惰化条件下甲烷爆炸临界参数的变化规律。此外,利用Chemkin软件模拟了C₂H₆/C₃H₈混合气体对甲烷爆炸过程中中间产物浓度的影响情况,并进行了敏感性分析。结果表明,C₂H₆/C₃H₈的存在降低了甲烷的爆炸上下限,增大了甲烷的爆炸危险度;在氮气惰化过程中甲烷的爆炸上限下降,爆炸下限上升,最终爆炸上下限重合,重合点处甲烷浓度和氮气临界浓度均随C₂H₆/C₃H₈的添加而逐渐减小;此外,C₂H₆/C₃H₈混合气体使甲烷爆炸过程中CO和·H的生成量逐渐增大,而CO₂、·O和·OH的生成量则有下降趋势,通过对爆炸过程中甲烷体积的敏感性分析,发现C₂H₆/C₃H₈的存在在某种程度上促进了甲烷爆炸。对比不同配比的C₂H₆/C₃H₈混合气体,发现C₃H₈含量越高,其对甲烷爆炸过程中相关参数的影响越大,这可为工矿企业的安全生产提供一定的理论依据。     

N2和CO2对液化石油气(LPG)惰化抑爆效能对比分析

为探究惰性气体对液化石油气（LPG）惰化抑爆效能的影响规律,本文运用可燃气体爆炸极限测定装置和可视化球型爆炸综合实验系统,分别测试了不同体积分数N₂和CO₂时,LPG的爆炸极限和压力特性参数并进行对比分析。结果表明：N₂和CO₂都会缩小液化石油气的爆炸极限,且对爆炸上限的影响程度更大;达到爆炸临界点时,CO₂体积分数为34%,小于N₂的43%,并且给出了爆炸危险区域的计算公式;在相同条件下,CO₂使得液化石油气的最大爆炸压力、最大爆炸压力上升速率降幅大于N₂的作用效果,且更好地降低了爆炸危险度和最大爆炸指数,提前了爆炸最猛烈程度的出现时间,减小爆炸危险时间。综合对比后发现,CO₂对LPG的抑爆性能要优于N₂。     

新型双流化床炉内NOx生成特性数值模拟

运用煤燃烧及NO_x生成的详细化学反应机理,通过搭建一维化学反应器网络（1D-CRN）,对一个新型双流化床（DCFB）内燃料型N转化为NO_x的基元化学反应进行了敏感性分析并讨论了反应温度、过量空气系数以及一、二次风配比对燃料型NO_x生成的影响。研究发现,在相同条件下,循环流化床炉膛出口的NO_x排放值为224.48 mg·m^-3,而双流化床炉膛出口的NO_x排放值为97.29 mg·m^-3,双流化床对于燃料型NO_x的减排幅度达到了56.66%。此外,促进NO_x生成的基元反应主要有R398（NH₂+O?HNO+H）、R1-N-1（N-Vol?NH₃+HCN）、R569（NCO+O₂?NO+CO₂）、R17（H+O₂?O+OH）等反应,而抑制NO_x生成的反应包括R411（NH₂+NO?N₂+H₂O）、R412（NH₂+NO?NNH+OH）、R570（NCO+NO?N₂O+CO）、R571（NCO+NO?N₂+CO₂）以及R5（Char+NO?Char+N₂+O₂）和R6（Soot+NO?n Soot+N₂+CO）等反应。这说明反应区域氧气浓度是影响NO_x生成的关键,低氧浓度可抑制燃料N向NO_x转化。另外,NO_x生成值随着反应温度的升高而降低,但随着过量空气系数和一次风所占比例的增大而增加。     

惰性气体对粉尘爆炸泄放特性影响的实验研究

爆炸泄放和爆炸抑制是工业上降低粉尘爆炸危害性的两个重要手段,同时实现粉尘爆炸抑制和泄放共同作用的效果值得关注。基于标准20 L球形粉尘爆炸装置侧向开泄放口,实验研究不同泄放口径和静态动作压力时CO₂/N₂对石松子粉泄放过程压力的影响,采用热重分析法分析了石松子粉尘分别在CO₂、N₂氛围的热重变化。结果表明,在20 mm泄放口径时,随着CO₂/N₂浓度的增加,泄放压力的降低幅值逐渐增大,且CO₂对粉尘爆炸泄放最大超压的减小效果要优于N₂。泄放压力值随着CO₂浓度的增加基本呈线性降低,当体系中的CO₂和N₂浓度增加到10%时对体系泄放压力值的降低效果开始趋于一致。对于40 mm泄放口径,添加相同浓度的CO₂体系泄放压力值要略低于N₂,降低幅值为6%~8%。对于60 mm泄放口径,CO₂/N₂两者抑制效果差别不大,且在添加浓度不超过8%时对体系泄放压力值的降低幅值影响较小。通过TGA曲线可以发现,在N₂气氛和CO₂气氛的热流条件中,石松子粉的热解过程在370℃左右开始出现明显的差异,CO₂气氛中石松子粉的热解速率要快于其在N₂气氛中的,因此在这个过程中CO₂的存在一定程度上会促进石松子粉的热解,随着热解温度进一步提升,CO₂对石松子粉热解的抑制效果开始逐渐体现。     

带压环境中CO2/H2O/N2气体稀释对合成气层流火焰速度的影响

合成气稀释燃烧是燃气轮机高效低污染燃烧的重要运行方式。本文以CO₂、H₂O和N₂为稀释气体，利用数值模拟方法研究稀释比对不同压力下合成气（CO/H₂/CH₄）层流火焰速度（S_L）的影响规律，并从自由基浓度变化、敏感性数值和生成速率（rate of production，ROP）三个方面解析三种气体的物理和化学作用机理。结果表明，S_L随燃烧压力和稀释比的增大而不断减小，其中CO₂对层流火焰速度的抑制最为显著。稀释气体的物理效应对层流火焰速度的影响远大于化学效应，但CO₂和H₂O的化学效应不能忽略。化学效应则是通过改变H和OH自由基浓度影响S_L，其中CO₂稀释降低H和OH自由基浓度，H₂O稀释则是降低H自由基浓度，从而降低合成气的层流火焰速度。进一步反应动力学分析发现了H/OH浓度变化在低压、加压下的主要化学反应路径，且受H₂O稀释的化学反应速率对压力较CO₂更为敏感。     

热解气氛对稻秆半焦组成及气化活性的影响

通过热解装置和热重仪分别研究了不同气氛（N₂、H₂和CO₂）对稻秆热解产物及半焦气化活性的影响。三种气氛中热解半焦产率为CO₂>N₂>H₂,焦油和气体产率为CO₂22;半焦中氧元素含量大小为CO₂>N₂>H₂,说明氢气中热解稻杆的脱氧效果最好;半焦中有机质相对百分含量随热解温度的升高而减小,并且CO₂>N₂>H₂,挥发分占总有机质的百分含量变化趋势与半焦中相反;K和Na析出率为CO₂22;半焦比表面积、孔容和孔径大小顺序为CO₂22;三种...     

一步法制备含氨基化合物的非对称CO2分离膜

采用一步相分离法,制备以聚醚砜（PES）为主体材料,二乙醇胺（DEA）为添加剂和氨基载体的膜,用于CO₂分离。考察了PES浓度、DEA浓度、膜厚度对CO₂/N₂分离性能的影响,同时考察了膜性能的长时间稳定性。当涂膜液中DEA/PES的质量比为12/26、刮刀与无纺布的距离为300 μm、进料气压力为0.11 MPa（表压）时,膜的CO₂渗透速率可达274 GPU,CO₂/N₂分离因子可达50。测试温度低于40℃时,DEA/PES膜的CO₂渗透速率和CO₂/N₂分离因子保持稳定。另外,对CO₂/N₂分离性能较好的DEA/PES膜（质量比为12/27）进行CO₂/CH₄分离性能测试,在1 MPa（表压）下性能优于商品膜。上述结果表明,本文研制的DEA/PES膜制备步骤简单,易于规模化制备,性能较优,在CO₂分离领域具有良好的应用前景。     

CO2/HCs混合工质亚临界与跨临界循环的性能分析

为了研究CO₂/HCs混合工质应用于热泵系统的性能，建立单级带节流阀亚临界循环和跨临界循环数学模型，分析了CO₂/R170,CO₂/R1270,CO₂/R290,CO₂/RC270 4种混合工质的特性、不同混合工质配比对循环制冷系数COP和高压压力的影响，以及蒸发温度和冷凝温度对循环性能的影响。结果表明：在亚临界循环中，性能最好的是CO₂/RC270,COP_c峰值为2.92,COP_h峰值为3.92,质量比在0.1/0.9左右，COP_c和COP_h分别比其他2种工质高出了9%、26%和7.1%、18%。在跨临界循环中，CO₂/R1270当质量比为0.96/0.04时，COP_c最大值为3.2,COP_h最大值为4.2; CO₂/R290能有效降低高压压力，当循环的高压压力在7.5 MPa下时...     

二氧化碳泡沫稳定性及聚合物对其泡沫性能的影响

基于CO₂气体性质的特殊性以及CO₂泡沫在多孔介质中表现出不同于其他气体泡沫的现象,利用气流法,选用十二烷基苯磺酸钠（SDBS）作为起泡剂,研究了CO₂泡沫的稳定性和衰减规律,以及聚合物部分水解聚丙烯酰胺（HPAM）对CO₂泡沫性能的影响。结果表明,在相同条件下,CO₂泡沫的稳定性比N₂泡沫差,并且CO₂泡沫的稳定性基本不受表面活性剂浓度的影响;CO₂泡沫的衰减曲线近似一条直线,泡沫形成后体积迅速减小。CO₂在水中具有较大的溶解度,泡沫的液膜渗透率系数大,因而泡沫稳定性差,也是造成CO₂泡沫在岩心内渗流规律区别于N₂泡沫的一个重要原因。HPAM的加入可以在一定程度上增强CO₂泡沫的稳定性,但同时也会使溶液起泡性能降低,所以实际应用时需要综合考虑泡沫特性,选择最佳的聚合物浓度。     

Chemical Effects of CO2 Concentration on Soot Formation in Jet-stirred/Plug-flow Reactor

Soot formation was investigated numerically with CO2 addition in a jet-stirred/plug-flow reactor （JSR/PFR） C2H4/OJN2 reactor （C/O ratio of 2.2） at atmospheric pressure. An updated Kazakov mechanism empha- sizes the effect of the O2/CO2 atmosphere instead of an O2/N2 one in the premixed flame. The soot formation was taken into account in the JSR/PFR for C2H4/O2/N2. The effects of CO2 addition on soot formation in different C2H4/O2/CO2/N2 atmospheres were studied, with special emphasis on the chemical effect. The simulation shows that the endothermic reaction CO2 ＋ H - CO ＋ OH is responsible of the reduction of hydrocarbon intermediates in the CO2 added combustion through the supplementary formation of hydroxyl radicals. The competition of CO2 for H radical through the above forward reaction with the single most important chain branching reaction H ＋ O2, ＇ O ＋ OH reduces significantly the fuel burning rate. The chemical effects of CO2 cause a significant increase in residence time and mole fractions of CO and OH, significant decreases in some intermediates （H, C2H2）, polycyclic aromatic hydrocarbons （PAHs, C6H6 and CI6H10, etc.） and soot volume fraction. The CO2 addition will leads to a decrease by only about 5% to 20% of the maximum mole fractions of some C3 to Clo hydrocarbon intermediates. The sensitivity analysis and reaction-path analysis results show that C2H4 reaction path and products are altered due to the CO2 addition.     

Inhibition of different types of inert dust on aluminum powder explosion

Aluminum powder explosion accidents occurred frequently, but the mechanism of aluminum powder explosion is unclear. Therefore, the inhibitive effect of aluminum powder explosion plays a key role. To evaluate the inhibition capacity of different kinds of carbonates and phosphates: NaH₂PO₄, (NH₄)₂HPO₄, NH₄H₂PO₄, KHCO₃ and NaHCO₃ on aluminum deflagrations, a standard 20-L spherical chamber was used to determine the explosion severity, characterized by the maximum explosion pressure (P_max). New parameters have been proposed: the minimum significant inert concentration (MSIC) and the minimum complete inert concentration (MCIC), which characterized the effect of inert. Experimental results showed that from the minimum significant inert concentration (MSIC) and the minimum complete inert concentration (MCIC), phosphate can have a significant inhibiting effect. 40% NaH₂PO₄ can totally inert the aluminum explosion, and 50% (NH₄)₂HPO₄ or 50% NH₄H₂PO₄ can also suppress the explosion. Through simulation, phosphate mainly acts via a chemical inhibition pathway, which inhibits the reaction of aluminum powder and oxygen by catalyzing the recombination of H atoms and O atoms. Carbonate performs inhibition in chemically, producing CO₂, diluting the oxygen around the aluminum powder. Studies indicated that the explosion pressure of the mixture decreases as the concentration of inert dust increases. However, when the concentration of carbonates was low, SEEP (suppressant enhanced explosion parameter) phenomenon was found. This research work has a potential industrial application in high hazard aluminum working condition, which can help decrease the explosion pressure and reduce the accident loss.     

Numerical Analysis on the Characteristics of Soot Particles in C2H4/CO2/O2/N2 Combustion

The purpose of this study is to investigate the characteristics of soot particles in C₂H₄/CO₂/O₂/N₂ combustion at equivalence ratio of 3.0-5.0. As the oxidant is switched from conventional air to CO₂/O₂/N₂ mixture, the key species C₂H₂, C₃H₃ responsible for formation of first aromatic ring, the typical aromatics and 4-ring aromatics total production rate all decrease greatly. In addition, with CO₂ mole fraction from 0.2 to 0.5 in the mixture, the soot particle number density, volume fraction, surface area density, which are three most important parameters to soot particle property, are suppressed obviously. Furthermore, the increasing content of CO₂ in the oxidizer influences mostly H, OH radical concentrations by two reactions: CO+OH=CO₂ H and H+O₂=O+OH, and the production rate of H, OH from the two reactions declined, which revealed that CO₂ in mixture has an inhibiting effect on soot particle generation.     

CO2 capture by double metal modified CaO-based sorbents from pyrolysis gases

High-temperature pyrolysis technology can effectively solve the problem of municipal solid waste pollution. However, the pyrolysis gas contains a large amount of CO₂, which would adversely affect the subsequent utilization. To address this problem, a novel method of co-precipitation modification with Ca, Mg and Zr metals was proposed to improve the CO₂ capture performance. X-ray diffraction (XRD) patterns and energy dispersive X-ray spectroscopy analysis showed that the two inert supports MgO and CaZrO₃ were uniformly distributed in the modified calcium-based sorbents. In addition, the XRD results indicated that CaZrO₃ was produced by the reaction of ZrO₂ and CaO at high temperatures. The effects of doping ratios, adsorption temperature, calcination temperature, CO₂ concentration and calcination atmosphere on the adsorption capacity and cycle stability of the modified calcium-based sorbent were studied. The modified calcium-based sorbent achieved the best CO₂ capture performance when the doping ratio was 10:1:1 with carbonation at 700 ℃ under 20% CO₂/80% N₂ atmosphere and calcination at 900 ℃ under 100% N₂ atmosphere. After ten cycles, the average carbonation conversion rate of Ca-10 sorbent was 72%. Finally, the modified calcium-based sorbents successfully reduced the CO₂ concentration of the pyrolysis gas from 37% to 5%.     

惰性气体对氢气/空气爆轰传播的抑制作用

常温常压条件下,在内径52 mm的不锈钢管道中开展了惰性气体对氢气/空气（H₂/air）爆轰的抑制实验研究,通过改变当量比（0.6、0.8、1.0、1.2、1.4）和惰性气体种类（CO₂、N₂、Ar）探讨了三种惰性气体对爆轰火焰速度的影响。结果表明,H₂/air爆轰通过可燃气与惰性气体分界面后,爆轰波发生解耦,火焰速度大幅度下降。整个速度下降过程分为快速下降、波动缓慢衰减、火焰消失三个阶段。三种惰性气体中CO₂的抑制效果最明显,其次是Ar和N₂。相较比热容差异影响,Ar和N₂的分子量差异在爆轰抑制中起到主导性作用。贫燃和富燃条件下爆轰在惰性介质中衰减程度均比化学计量比工况下明显,其中富燃条件下爆轰在惰性介质中的衰减更为明显。