生物质流化床富氧气化的实验研究

在常压流化床装置上进行了生物质在富氧条件下定向气化的实验研究。实验主要考察了氧的当量比和氧体积分数对气化气组成、碳转化率和气体热值的影响。当量比值是与温度紧密联系的一个量，本实验主要通过调节进料量来改变它的值，随着当量比的变化（0.21～0.29），燃气成分也会改变，其中变化最大的是H2、CO。H2体积分数显著增加，CO和CH4体积分数有降低的趋势，使燃气热值降低；氧体积分数是富氧气化过程中较重要的参数，在实验研究的范围内，发现增大氧气体积分数可以提高H2体积分数及有利于调节H2/CO(体积分数)的比值。当氧气体积分数从21％提高到45％，H2体积分数从20％增加到27.7％，H2/CO(体积分数)从0.38增加到0.75，比较接近合成液体燃料的气体比值。     

木屑在鼓泡流化床和循环流化床中气化特性的对比研究

对木屑在内径分别为0.3m×0.3m的鼓泡流化床气化炉（BFBG）和内径0.4m的循环流化床气化炉(CFBG)中的气化特征进行了对比,重点考察了当量比对生物质气化特性的影响。实验结果表明,在相同当量比下,由于CFBG操作气速明显高于BFBG,床内强烈的气固传热传质,使得CFBG可以获得较高的热解速率,同时可以使 CFBG在较高温度下运行。较高的运行温度不仅有利于二次裂解气化反应,使可燃气体质量明显好于BFBG,同时也减少了燃气中焦油的量。在较低气化当量比下(ER≤0.28),CFBG比BFBG可以获得更高的气体产率、碳转化率和气体效率;在较高当量比下,(ER＞0.28),CFBG和BFBG的气体产率、碳转化率和气体效率则相差不大。     

煤和生物质共气化制备富氢气体的实验研究

在煤处理量为8kg/h的小型流化床反应器上,以富氧空气和水蒸气为气化介质,对煤和生物质共气化制取富氢燃气进行了实验研究。在850℃～1 050℃主要考察了空气当量比、水碳比、生物质比例和生物质种类对燃气组成和气体产率的影响。结果表明,对煤和稻草混合体系,稻草质量比为33%时,空气当量比增加,CO2含量显著增加,H2、CO和CH4含量减少,气体产率增加;水碳比增加,CO2和CH4含量增加,CO和H2含量减小,气体产率先增加后减小;生物质比例增加,CO2、H2和CH4含量增加,CO含量降低,气体产率先增加后减小,当生物质比例小于50%时,可以实现体系的稳定运行。对于三种不同的煤与生物质混合体系,煤与高粱秆共气化所得煤气中H2含量最高,气体产率的顺序为:煤/木屑煤/高粱秆煤/稻草煤。实验中H2在煤气中的体积分数最高可达37.25%,最大产率为0.54m3/kg。     

Experimental and mechanism studies on simultaneous desulfurization and denitrification from flue gas using a flue gas circulating fluidized bed

The oxidizing highly reactive absorbent was prepared from fly ash,industry lime,and an oxidizing additive M.Experiments of simultaneous desulfurization and denitrification were carried out in a flue gas circulating fluidized bed(CFB).The effects of influencing factors and calcium availability were also investigated on the removal efficiencies of desulfurization and denitrification.Removal efficiencies of 95.5%for SO2 and 64.8%for NO were obtained respectively under the optimal experimental conditions. The component of the spent absorbent was analyzed with chemical analysis methods.The results in- dicated that more nitrogen species appeared in the spent absorbent except sulfur species.A scanning electron microscope(SEM)and an accessory X-ray energy spectrometer were used to observe micro-properties of the samples,including fly ash,oxidizing highly reactive absorbent and spent absorbent.The simultaneous removal mechanism of SO2 and NO based on this absorbent was pro- posed according to the experimental results.     

Parallel consecutive reactions in a fluidized catalyst bed

The two-phase model of Werther is applied to a parallel consecutive triangular reaction scheme. An analytical solution is obtained and used to predict the performance of a fluidized bed reactor producing maleic anhydride from benzene oxidation. The model predictions agree with experimental data. The model is also useful for examining the sensitivity of various parameters, thus guiding the direction of future experiments.     

PVC塑料流化床气化试验研究

为开发城市生活垃圾低污染流化床气化与旋风燃烧熔融技术,研究了垃圾中广泛存在的PVC塑料在流化床内的气化特性与污染物生成机理。不同温度和过量空气系数下进行了流化床PVC气化试验,分析了不同工况对PVC中Cl转化为HCl的影响。实验结果表明,反应高于600 ℃、过量空气系数大约0.4时,Cl转化为HCl的选择性达到95％以上;气化效率达到22％～25％,气化气热值达到2 000 kJ/m3～2 300 kJ/m3。反应高于700 ℃,PVC流化床气化生烟量明显减少,过量空气系数0.6时,生烟量减少到PVC质量的10％左右。提出的HCl析出与生烟机理较好地解释了试验结果,为城市生活垃圾气化熔融技术提供了相关基础数据与污染物生成及控制方法。     

气化介质对生物质多孔床料流化床气化产气特性的影响

在自制小型常压流化床内采用多孔介质为床料,对生物质进行气化实验,分别考察了富氧气氛下温度和氧气浓度、水蒸气气氛下温度和水蒸气流量及不同种类床料对生物质产气特性的影响。结果表明,多孔床料下气化产气中可燃气体积分数随气化温度的提高而增大;随氧气浓度的增加,产气中H2的体积分数从14.52%增加到19.71%,CO的体积分数从43.41%降低到36.41%;气化剂水蒸气流量对生物质气化影响存在最佳范围;多孔床料种类不同对H₂和CO的生成以及对低碳氢化合物（C_xH_y）的催化裂解强度的促进作用也不同。     

生物质气再燃减少流化床N_2O排放的实验研究

以生物质气化气作为再燃燃料,在小型流化床反应器内进行了N2O脱除的实验研究。研究了生物质气化气投入位置、料层高度、再燃燃料比、烟气含氧量和反应温度对N2O排放的影响。结果表明,距布风板200 mm的B喷口较离布风板较近的A喷口(距布风板100 mm)对应的N2O转化率高;反应温度为850℃、按照N2O/N2配置模拟烟气的情况下,B口喷入生物质气量为1%,床料CaO高度为10 mm时N2O接近完全分解;反应温度为850℃,床层高度大于20 mm时,从B口喷入大于0.4%比例的生物质气对应N2O分解率高于95%。     

Transient phenomena in o-xylene oxidation in a fluidized bed reactor

The effect of stirring a vanadium-titanium-tellurium catalyst on the yield of the selective oxidation products for oxidation of o-xylene in fluidized bed reactors has been studied. It is shown that the stirring of catalyst pellets increases the yield of phthalic anhydride.

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生物质流化床氧气-水蒸气气化实验研究

在小型流化床气化装置上进行了氧气-水蒸气气化实验,考察了原料、当量比、水蒸气配比、温度、二次风和床料对气化特性的影响。结果表明,原料中C和H含量越高,气化气中H₂和CO含量越高,焦油含量越低;当量比为0.27和水蒸气配比为0.6时,H₂含量达到最大值;温度的升高可提高H₂含量,在840 ℃以上,可提高CO含量;二次风从进料口偏上且二次风比率为15%通入,气体组分变化较明显,二次风通入点位置越高,焦油含量降低幅度越大;白云石和石灰石裂解焦油和提高H₂含量的活性高于橄榄石,但同时明显提高了气体中的灰分含量。     

Continuous high-temperature fluidized bed pyrolysis of coal in complex atmospheres: Product distribution and pyrolysis gas

This study is devoted to investigating the continuous coal pyrolysis in a laboratory fluidized bed reactor that fed coal and discharged char continuously at temperatures of 750–980 °C and in N₂-base atmospheres containing O₂, H₂, CO, CH₄ and CO₂ at varied contents. The results showed that the designed continuous pyrolysis test provided a clear understanding of the coal pyrolysis behavior in various complex atmospheres free of and with O₂. The effect of adding H₂, CO, CH₄ or CO₂ into the atmosphere on the tar yield was related to the O₂ content in the atmosphere. Without O₂ in the atmosphere, adding H₂ and CO₂ decreased the pyrolysis tar yield, but the tar yield was conversely higher with raising the CO and CH₄ contents in the atmosphere. In O₂-containing atmospheres, the influence from varying the atmospheric gas composition on the product distribution and pyrolysis gas composition was closely related to the oxidation or gasification reactions occurring to char, tar and the tested gas.     

粉粒流化床中松木生物质热解特性的研究

通过冷模实验考察了双颗粒流化床的流化特性。结果表明,在适宜的气速范围内,双颗粒流化床层内部可保持较好的流化状态。松木生物质在粉粒流化床反应器中的热解和催化热解实验结果表明,生物质热解时挥发分的释放存在一个最快的温度区域,生物质中约92%的挥发分在723 K时即可释放完全。773 K时,生物质热解产物中的无机气体(IOG)、低碳烃气体(HCG)和碳氢化合物液体(HCL)的收率之和只有3.1%。随着热解温度的升高,IOG、HCG和HCL的收率均逐渐增加,1 173 K时,其收率之和达到58.7%,且产物主要以CO为主。CoMo-B催化剂可有效促进生物质催化加氢热解产物的二次气相反应,在863 K下可得到6.3%,轻质芳烃化合物(苯、甲苯、二甲苯和萘)是1 173 K下非催化过程的两倍。     

Hydrodynamics and mixing in three-phase fluidized bed bioreactors

The effects of solid particles on hydrodynamics and mixing in a three-phase fluidized bed bioreactor were discussed. The gas holdup, bubble size, and liquid-phase axial dispersion coefficient were measured in a 0.25-m id bubble column bioreactors containing low-density particles. The presence of low-density solid particles slightly increased gas holdup. The decrease in average bubble diameter with solid presence was found. For the three-phase system, the liquid-phase axial dispersion coefficients were higher than for the two-phase system. We extended a model for a gas holdup developed for a gas-liquid two-phase bubble column bioreactor to a gas-liquid-solid three-phase fluidized bed bioreactor. Using the present data and available data in the literature, the predictions of the proposed model were examined. The proposed model agreed with a wide range of the experimental data. A theoretical correlation for liquid-phase axial dispersion coefficient was developed using Kolmogoroff's theory of isotropic turbulence. Reasonable agreement was obtained between the predicted and experimental values of axial dispersion coefficient.     

RDF流化床燃烧过程NOx生成比较研究

随着中国经济的迅速发展和城市化进程的加快,由此带来的负作用凸现：各种资源的消耗不断增加;同时这种传统的高消耗、低产出、高污染的经济发展带来的环境污染也非常严重。据不完全统计,2003年中国城市生活垃圾总量为1．9亿t,并以每年8％～10％的速度递增,对垃圾进行简单填埋、焚烧不但污染土壤和地下水,     

On the heterogeneous behaviour in a 2D fluidized bed

The aim of the present paper is to study the influence of the n -index in the porosity function of Richardson–Zaki on the heterogeneous behaviour in a fluidized bed. This parameter takes into account the group effect of particles on the drag of an isolated particle. We have shown up different behaviours of the bed when changing its value.     

气固流化床内射流特性的研究

采用Brandani等的数学模型模拟了中心射流宽度为0.01m的二维气固流化床(高1.6m、宽0.3m)内鼓泡和射流的瞬态及时均流体动力学特性。一种典型的Geldart B颗粒――砂子(粒径为500mm、密度为2660kg/m3)作为研究的模拟物料。瞬态结果表明，床内射流产生和发展、射流崩塌后所形成气泡尺寸以及全床内的气体速度场和空隙率均存在明显的非对称性，但是由压力信号功率谱密度得到的时均压力特性则有较好的对称性。因此，对于商业化稳定运转的射流床，可以用半床模拟结果近似解释整床特性；然而，在考察射流床的瞬态特性时，半床模拟结果与整床结果存在明显偏差。     

Pyrolysis characteristics of pine biomass in a powder-particle fluidized bed

通过冷模实验考察了双颗粒流化床的流化特性.结果表明,在适宜的气速范围内,双颗粒流化床层内部可保持较好的流化状态.松木生物质在粉粒流化床反应器中的热解和催化热解实验结果表明,生物质热解时挥发分的释放存在一个最快的温度区域,生物质中约92％的挥发分在723K时即可释放完全.773K时,生物质热解产物中的无机气体(IOG)、低碳烃气体(HCG)和碳氢化合物液体(HCL)的收率之和只有3.1％.随着热解温度的升高,IOG、HCG和HCL的收率均逐渐增加,1173K时,其收率之和达到58.7％,且产物主要以CO为主.CoMo-B催化剂可有效促进生物质催化加氢热解产物的二次气相反应,在863K下可得到6.3％,轻质芳烃化合物(苯、甲苯、二甲苯和萘)是1173K下非催化过程的两倍.     

Fluidization characteristics of sawdust in a cold flow fluidized bed

India has abundance of biomass such as rice husk, bagasse, wheat straw, sawdust etc. which is used as a main or auxiliary fuel in the fluidized bed combustor, gasifier and pyrolizer. Design of such fluidized bed equipments require the knowledge of minimum fluidization velocity (U_mf), complete fluidization velocity (U_cf) and transport disengagement height (TDH). The present work reports the fluidization characteristic, U_mf, U_cf and TDH of the individual size groups of sawdust and mixture thereof. The results indicate that the U_mf and U_cf have a tendency to increase with increase in particle diameter, however the TDH shows the reverse trend. The sawdust particle size of 925 and 1200 ​μm showed significant difference between their U_mf and U_cf, an essential parameter for controlled fluidization. Based on the experimental work new correlations for the prediction of U_mf, U_cf and TDH for sawdust sample are proposed. The proposed correlations of U_mf, U_cf and TDH are in good agreement with experimental values and the deviations found within the range of nearly ±10% for all the samples.     

灰熔聚流化床气化炉分布分离结构的模拟研究

通过CFD双欧拉模型模拟了灰熔聚流化床气化炉内气体、固体颗粒于不同气体分布器、灰分离器结构下的流动行为,阐明了不同中心射流气速下的气体、固体流动循环状况;环管内气流分布与扩管张角的关系以及对颗粒运动的影响。研究结果为认识和改善气化炉煤灰的结渣、团聚、分离等过程提供了一定的理论基础。     

Design of a fluidized bed reactor for microencapsulated urease

A fluidized bed reactor was designed, constructed, and tested for handling microencapsulated urease. The working volume of the reactor was 10 mL, with a minimum fluidization velocity of 7.7×10⁻⁵ m/s. An even suspension of the microcapsules was obtained at fluid velocities between 1.5×10⁻⁴ and 6.0×10⁻⁴ m/s without breakage of the shear-sensitive microcapsules. The mixing behavior in the reactor was evaluated using pulse input tracer experiments and the hydrolysis rates of urea in continuous flow experiments were evaluated under various operating conditions.