纸浆黑液对福建无烟煤水蒸气催化气化的动力学和补偿效应

在常压热分析仪上,采用纸浆黑液催化剂对福建无烟粉煤的水蒸气气化反应动力学进行了研究,在850～950℃温度范围内测定了催化剂浓度由0增至10％时的碳转化率随气化时间的变化。结果表明,纸浆黑液具有显著提高碳转化率和气化速率的作用,进而确定了实验条件下的纸浆黑液催化剂加载饱和浓度;在此基础上采用缩芯模型关联出无烟粉煤水蒸气催化气化反应动力学参数,分析表明,该催化气化过程存在明显的补偿效应,最后给出纸浆黑液对无烟粉煤水蒸气催化气化包括补偿效应的动力学方程。     

福建无烟煤燃烧特性及催化气化表观动力学研究

基于对福建尤溪无烟煤燃烧特性分析,在内径为26mm的实验室小型流化床反应器中进行福建尤溪无烟粉煤与NaOH浸渍混合后的水蒸气催化气化实验。考察了4g/min水蒸汽流量下,不同催化剂加载浓度及不同温度对碳转化率的影响,并对催化气化表观动力学参数进行拟合与计算。研究结果表明：气化温度的升高和催化剂加载浓度的增大能显著提高碳...     

煤催化气化研究进展与煤-纸浆黑液共气化

论述了煤催化气化研究领域中催化剂种类,催化气化反应机理及其反应动力学的现状,发展方向以及存在的主要问题。在此基础上结合纸浆黑液组成特性和处理现状,提出煤－纸浆黑液共气化设想。     

纸浆黑液制气化型煤黏结剂研究

利用正交设计法研究纸浆黑液经化学改性制气化型煤黏结剂的工艺技术条件,结果表明:1 000mL纸浆黑液(固体质量分数45%)与80mL有机试剂A在80℃下恒温反应2h,然后升温至95℃,加入30mL有机试剂B,恒温反应1h;最后加入50g无机试剂M,充分搅拌0.5h,得到性能优良的纸浆黑液气化型煤黏结剂。用该黏结剂生产型煤,其抗压强度、落下强度、热稳定性分别为96kg/球、96%、95%,并具有良好的防水性能,完全达到了气化型煤的质量要求。     

福建无烟粉煤催化气化的工业化前景

概述了煤炭资源对我国国民经济的作用,指出了洁净煤技术中无烟粉煤气化的重要性,特别针对福建低活性与低灰熔点的劣质无烟粉煤,首次在实验室采用流化床催化气化的方式可获得较高煤气产率与煤气热值的令人鼓舞的高于常规高温气化的结果,进而论述了廉价的催化剂来源,碱灰渣的综合利用,催化气化的煤气成本与合理床型,这将为第三代煤气化技术─—催化气化工艺的进展与工业化试验提供了重要依据与实质研究．     

福建无烟煤CO2气化过程纸浆黑液和钙混合物的催化活性

CO2 gasification of Fuijian high-metamorphous anthracite with black liquor （BL） and/or mixture of BL and calcium stuff （BL＋Ca） as catalyst was studied by using a thermogravimetry under 750-950℃ at ambient pressure. When the coal was impregnated with an appropriate quantity of Ca and BL mixture, the catalytic activity of CO2 gasification was enhanced obviously. With a loading of 8%Na-BL＋2%Ca, the carbon conversion of three coal samples tested reaches up to 92.9%-99.3% at 950℃ within 30min. The continuous formation of alkali surface compounds such as （[-COM], [-CO2M]） and the presence of exchanged Ca, such as calcium phenolate and calcium carboxylates （COO）2Ca, contribute to the increase in catalytic efficiency, and using BL＋Ca is more efficient than that adding BL only, The homogeneous model and shrinking-core model were applied to correlate the data of conversion with time and to estimate the reaction rate constants under different temperature. The corresponding reaction activation energy （Ea） and pre-exponential factor of three anthracites were estimated. It is found that Ea is in the range from 73.6 to 121.4kJ·mol^-1 in the case of BL＋Ca, and 74.3 to 104.2kJ·mol^-1 when only BL was used as the catalyst, both of which are much less than that from 143.5 to 181.4kJ·mol^-1 if no catalyst used. It is clearly demonstrated that both of BL＋Ca mixture and BL could be the source of cheap and effective catalyst for coal gasification.     

华亭粉煤流化床气化

华亭矿粉煤经小型流化床气炉试烧表明,该煤种较为适合于直接粉煤气化,产气可作为化肥厂的原料气。     

微型流化床中生物质半焦水蒸气气化反应特性及动力学研究

利用微型流化床反应分析仪考察了1123~1223 K及10%~40%蒸汽分压(SP)条件下生物质半焦-水蒸气气化的反应特性并计算动力学。结果表明：升高温度和SP有利于缩短反应时间,提高产物(H₂、CO和CO₂)生成率及总C转化率。低温(1123 K)下,反应受SP影响较大,以H₂最为明显,增幅达1.97倍;在1223 K、SP≥20%条件下,因受活性位点制约,SP对反应影响较小。随温度升高,CO/CO₂体积产率比呈现出先减小后增大趋势;在1123 K和1173 K下,随SP升高,CO/CO₂的体积产率比值降低;在1223 K下,该值维持在1.25左右。采用缩核模型求取不同SP下总碳转化活化能(E_a)在71.29~76.78 kJ/mol范围内,H₂、CO₂和CO的生成活化能分别在95.44~101.82、83.56~89.35和70.41~74.86 kJ/mol之间。测试结果弥补了现有分析仪难以测定气化过程中气体产物生成特性和动力学的局限性。     

生物质流化床空气-水蒸气气化模型研究

根据流化床反应器特点,结合生物质气化动力学反应机理,建立了生物质在流化床内气化的等温稳态、一维二相动力学模型。该模型所做的主要假定如下:流化床分为气泡相和乳相,在气泡相和乳相内均存在化学反应,考虑二相内的轴向气体扩散,生物质热解过程瞬时完成,主要考虑焦碳以及CO,CO2,H2,H2O,CH4等在流化床内发生的8个主要化学反应。数学模型属于常微分方程组边值问题,利用数值计算软件M atlab7.0进行编程求解。以木粉为原料,将模型结果与实验结果进行了对比,模拟结果与试验数据符合良好,在一定程度上证明了模型的有效性和可靠性。     

灰熔聚流化床粉煤气化技术

灰熔聚流化床粉煤气化技术是８０年代以来开发研究的。该技术是在流化床用氧化剂形成局部高温的办法来提高碳转化率，因而拓宽了煤种适应性，使灰渣在高温下团聚成又大又重的粒子而减少了排灰碳损失。     

纸浆黑液和钙混合催化剂进行高变质无烟煤水蒸气气化的研究

The catalytic effects of single and mixed catalysts, i.e. single 3%Ca and 5%Na-BL（black liquor） catalysts and mixed 3%Ca＋5%Na-BL catalyst, on carbon conversion, gasification reaction rate constant and activation energy, relative amount of harmful pollutant like sulphur containing gases have been investigated by thermogravimetry in steam gasification under temperature 750℃ to 950℃ at ambient pressure for three high-metarnorphous anthracites （Longyan, Fenghai and Youxia coals in Fujian Province）. The mixed catalyst of 3%Ca＋5%Na-BL increases greatly the carbon conversion and gasification rate constant by accelerating the gasification reaction C＋H2O→CO＋H2 due to presence of alkali surfacecompounds [COM], [CO2M] and exchanged calcium phenolate and calcium carboxylate （-COO）2. By adding CaCO3 into BL catalyst in gasification, in addition to improving the catalyst function and enhancing the carbon conversion, the effective desulphurization is also achieved, but the better operating temperature should be below 900℃. The homogenous and shrinking core models can be successfully employed to correlate the relations between the conversion and the gasification .time .and to estimate the reaction rate constant, The reaction acUvaUon energy and pre-exponential factor are estimated and the activation energy for mixed catalyst is in a range of 98.72-166.92 kJ·mol^-1, much less than 177.50-196.46 kJ·mol^-1 for non-catalytic steam gasification for three experimental coals.     

Reaction kinetics of gasification of black liquor char

CO₂ gasification of black liquor char, prepared from kraft spent pulping liquor is studied thermogravimetrically up to 775°C. The gasification rate is described by Langmuir-Hinshelwood type kinetics and activation energy is similar to that found for alkali metal impregnated porous carbons. However the rate is about 20 times larger than that of coal char mixed with 10-20% Na₂ CO₃. CO inhibition is relatively small and the rate is first order in carbon up to 80% conversion. The behavior is explained by a fine and three-dimensional dispersion of sodium salts in the char. The rate is insensitive to pulping conditions over the range of industrial practice.     

Intrinsic kinetics and external diffusion of catalytic steam gasification of fine coal char particles under pressurized and fluidized conditions

Catalytic steam gasification of fine coal char particles was carried out using a self-made laboratory reactor to determine the intrinsic kinetics and external diffusion under varying pressures (0.1-0.5 MPa) and superficial gas flow velocities (GF Vs) of 13.8- 68.8 cm· s^-1. In order to estimate the in-situ gas release rate at a low GFV, the transported effect of effluent gas on the temporal gasification rate pattern was simulated by the Fluent computation and verified experimentally. The external mass transfer coefficients(kmam) and the effectiveness factors were determined at lower GF Vs, based on the intrinsic gasification rate obtained at a high GFV of 55.0 cm·s^-1. The kmamwas found to be almost invariable in a wider carbon conversion of 0.2-0.7. The variations of kmam at a median carbon conversion with GFV, temperature and pressure were found to follow a modified Chilton-Colburn correlation:Sh=0.311Re^2.83Sc1/3(P/P0)^-2.07 (0.04相似文献   

Experimental study on catalytic steam gasification of natural coke in a fluidized bed

The gasification characteristics of natural coke from Peicheng mine with steam were investigated in a fluidized bed reactor. The effects of catalyst type, composition and dosage of catalyst on the yield, components and heating value of product gas, and carbon conversion rate were examined. The results show that fluidized bed gasification technology is an effective way to gasify natural coke. Also the results indicate that individual addition of K-, Ca-, Fe-, Ni-based catalyst effectively increases the gasification reaction rate of the natural coke samples. With the increase in catalyst dosage, the yield and heating value of product gas per hour increase obviously, and carbon conversion rate is improved substantially. Each of aforementioned catalysts has similar catalytic effect and trend, among which the effect of Ca-based catalyst is a little weaker. The optimum metal atom ratio of mixed catalyst is Fe/Ni/others = 35/55/10, and the mixed catalyst displays maximum catalytic performance when the catalyst dosage in the natural coke is about 4%. The experimental findings provide an interesting reference for large-scale development and utilization of natural coke.     

Fluidized bed gasification of coal

Gasification of high ash India coal has been studied in a laboratory-scale, atmospheric fluidized bed gasifier using steam and air as fluidizing media. A one-dimensional analysis of the gasification process has been presented incorporating a two-phase theory of fluidization, char gasification, volatile release and an overall system energy balance. Results are presented on the variation of product gas composiiton, bed temperature, calorific value and carbon conversion with oxygen and steam feed. Comparison between predicted and experimental data has been presented, and the predictions show similar trends as in the experiments.     

Coal pyrolysis and gasification in a fluidized bed thermogravimetric analyzer

The kinetics and modelling of coal gasification were studied in the newly developed fluidized bed thermogravimetric analyzer. The total weight loss obtained from the fluidized bed reactor and the total gas product are in general agreement. The presented model for the micro‐fluidized bed reactor encompasses the kinetics of coal pyrolysis as well as the gasification reactions. For coal pyrolysis, the resulting activation energies for the individual gases were 34.7 to 59.8 kcal/mol. These values are 19 to 21 % lower than those found in the literature for similar coals. This decrease of the activation energies of the endothermic pyrolysis reactions is attributed to a gradient of temperature of 185 to 209 °C. The obtained activation energy for the CO shift reaction is 46.6 kcal/mol, increasing by 20 % from the one used in the literature. This increase of the activation energy of such a mildly exothermic reaction represents an equivalent of 170 °C gradient of temperature. The effects of temperature on the yield and the composition of the gas product are studied. Experimental results and equilibrium data are also compared. The model shows reasonably good agreement with the experimental results, except for the water gas shift reaction.