Fluidization behavior of oil-contaminated sand

Hydrodynamic behavior of oil-polluted particles of sand was investigated in transparent glass column. The onset of fluidization of sand beds increased with the oil content of the bed. An increase of cohesive forces related to the higher content of liquid (oil) caused deterioration of the quality of fluidization. An empirical correlation was developed to predict the dimensionless gas velocity that keeps the bed of sticky particles fluidized. Results of this work can be employed for the design of fluidized-bed remediation units for oil-polluted sands and soils. An erratum to this article is available at .     

Geldart‘sA,B和D类粒子振动流化床空气动力学的研究

主要研究Φ１４８ｍｍ的振动圆柱形流化床的空气动力学，研究了振动强度为１－５ｇ，静止床层高度为１００ｍｍ－２００ｍｍ和属于Ｇｅｌｄａｒｔ‘ｓＡ，Ｂ和Ｄ物料等条件下床层压降，最小流化气速和床层空隙率变化，考察振动条件下振动参数，颗粒物性和床层高度等操作参数对空气动力学的影响，得出固定床段的床层压降的升高和最小流化速度的降低是由于床层空隙率的降低所造成的，并由实验结果关联出床层夺降和最小流化气计算式，同     

加压流化床流化性质的实验与模拟研究

在二维射流流化床装置中,考察了压力对颗粒和气泡运动的影响规律.通过使用摄像技术详细的记录了压力下气泡的行为,并对其进行了分析,由此解决了较高压力下测量流态化性质较为困难的问题.数值研究通过CFD双欧拉模型模拟了带有V形分布器和中心射流的二维流化床内压力对气泡大小、床的膨胀率和射流深度的影响.实验和理论结果表明,在加压状态下,射流气速和分布板气速对气泡的产生、大小及形状有不同的影响.在较高的操作压力下,射流气速增加,气泡变长;分布器气速增大,气泡则变大;射流高度随着分布器气速的增加而降低.模拟结果与实验数据吻合较好,由此该模型为研究较高操作压力下射流流化床流化性质提供了有利的工具.     

流化床生物质与煤共气化特性的初步研究

在热天平和流化床实验装置中研究了生物质与煤的共气化特性,采用程序升温热重法对稻秆焦、高粱秆焦、玉米秆焦和神木煤焦以及生物质焦与煤焦混合物进行水蒸气气化研究。结果表明,生物质焦和煤焦的反应活性依次增大,其顺序为高粱焦>稻秆焦>玉米焦>神木煤焦。一定温度下,生物质焦与煤焦混合物的气化碳转化率高于各自气化碳转化率的加和。在流化床气化实验中,比较了单独煤气化与稻秆/煤混合物气化的结果,实验结果表明,混合物气化碳转化率、气体中可燃组分的体积分数均高于单独煤气化,气体中CO2的体积分数低于单独煤气化CO2的体积分数。     

振动流化床双组分颗粒的轴向浓度分布的研究

在内径为１４８ｍｍ的振动圆柱形流化床中研究焦或渣与介质混合物的轴向浓度与分离／混合程度，考察了振动参数、床层高度和流化气速对分离效率的影响，得出床层高度比较高时，有利于焦或渣在介质中分离的结果和较佳的分离操作范围，为获得细粒焦渣混合物的充分分离奠定了基础。     

Measurement of the fluidized velocity in gas-solid fluidized beds based on AE signal analysis by wavelet packet transform

An energy distribution theory was presented based on regular evolvement of energy fraction of acous-tic signals with fluidization velocity. Wavelet packet analysis was used in processing the acoustic sig-nals originated from particle impact on the wall of a fluidized bed. A new criterion of judging incipient fluidization(Umf) velocity and minimum turbulent velocity(Umt) was proposed according to the energy distribution theory. Experiments were performed with five groups of high density polyethylene(PE) particles and one bimodal PE to acquire incipient fluidization velocity and minimum turbulent velocity by using the criterion. The feasibility of this method in obtaining characteristic fluidization parameters was further verified by comparing it to results from the pressure drop method and the empirical value from industry.     

芦苇浆黑液在流化床上的热解实验研究

为了掌握芦苇浆黑液的热解行为,利用流化床在530、580、630、680、730和780 ℃ 六个床温下对芦苇浆黑液在氮气氛围下的热解过程进行了实验研究,分析了床温对气相产物、碳的转化率、NO_x和SO₂的排放浓度、焦油成分和热解焦微观形貌的影响。结果表明,热解气中的主要成分为CO、CH₄、CO₂和H₂,床温的升高有利于H₂和CO的生成,而不利于CH₄和CO₂的生成;可燃气体积分数随着床温的升高而升高,其值从59.2%(530 ℃)升高到66.1%(780 ℃);床温较高时,热解产生的焦油量较少,其中,多环芳烃化合物的相对含量较多,该值在780 ℃时最高为46.88%。     

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.     

生物质与石油焦共气化特性的研究

在内径为50mm,高约950mm的固定床反应器上对生物质与石油焦共气化特性进行了研究。研究了气化模式、石油焦添加比例、添加方式、粒径大小及气化温度对气化效果及焦油量的影响。结果表明,石油焦可以起到催化裂解生物质焦油的作用。随着氧气的体积分数从2%增加到15%时,气体的热值从5.35MJ/m³降低到2.98MJ/m³。在气化温度为700℃时,四种氧气含量下生物质单独气化时焦油产率平均值为6.4%,气体热值为4.31MJ/m³;生物质和石油焦混合气化时焦油产率平均值为2.9%,气体热值为5.19MJ/m³。石油焦的最佳添加比例为1∶1。生物质和石油焦不混掺焦油的产率最大,混掺其次,石油焦提前加入效果最好。随着添加石油焦粒径的增大,石油焦对生物质气化焦油的裂解率逐渐降低。在两种气化模式下,随着气化温度的升高,焦油的产率均逐渐降低。     

循环流化床富氧气化实验研究

在循环流化床富氧气化实验台上,通过调节水蒸气流量使气化温度基本稳定在910℃,研究了不同氧气浓度及气化当量比对煤气组分、产气率、冷煤气效率及碳转化率的影响。结果表明,氧气浓度从25%增加至40%时,N2体积分数从48.82%降低至33.83%,H2从21.47%不断增加至27.59%,CH4基本不变;受水蒸气流量影响,氧气浓度高于35%时,CO体积分数降低,CO2体积分数增加;氧气浓度40%时的煤气热值为空气气化煤气热值的1.84倍,产气率随氧气浓度增加从2.35 m3/kg降至2.13 m3/kg,冷煤气效率和碳转化率不断增大;当气化当量比从0.20增加至0.29时,N2体积分数先降低后升高,H2体积分数从24.01%增加到25.46%后基本保持不变,CO和CH4持续减小,CO2不断增加,产气率由1.94 m3/kg升高到2.29 m3/kg;受水蒸气和气化当量比综合影响,冷煤气效率先增大后减小,碳转化率持续增加。     

循环流化床煤燃烧/热解双反应器压力分布的实验研究

实验测量了一种新型的循环流化床煤燃烧/热解冷模反应器中提升管及立管内的压力分布，其中提升管的内径为100 mm、高为6 m;立管内径为44 mm、高为3 m，热解室的截面为200 mm×200 mm、高为770 mm。分别考察了提升管内的表观气速Ur、循环量Gs、加到热解室内的松动气量Qa以及初始装料量G等对系统压力分布的影响。结果表明，在立管底部阀门开度不变的情况下随着Ur的增加，提升管及立管内的压力梯度都趋于减小；在提升管内表观气速一定的情况下随着循环量Gs的增加，提升管及立管内的压力分布也随之增大；加到热解室内的松动气对立管内的压力分布影响较大，而对提升管内的压力分布影响相对较小；在立管底部阀门开度及Ur一定的情况下，随着初始装料量的增加提升管及立管内的压力分布也趋于增大。     

A Study of Carbon Deposition on Catalysts During the Catalytic Partial Oxidation of Methane to Syngas in a Fluidized bed

The deposition of carbon on catalysts during the partial oxidation of methane to syngas has been investigated in a fluidized bed. It was found that the relative rate of carbon deposition follows the order Ni>>Pd>Pt, Rh. Although the rate of carbon deposition in the fluidized bed was much lower than that in the fixed bed, carbon deposition could still be detected in the fluidized bed if a CH₄ /O₂ ratio in greater than 2.3 was used.     

晋城煤粒度变化对灰熔融性影响规律研究

探索山西晋城煤在灰熔聚流化床气化过程中的结渣机理。采用山西晋城无烟煤,将其破碎到不同粒径,采用XRF、XRD、AFT、SEM和FactSage~(TM)研究了煤的灰分、煤灰化学组成、矿物组成和熔融性随煤样粒径变化规律。结果发现,对于破碎到6 mm以下的晋城煤样,不同粒径子样煤灰化学组成和熔融温度差异不大;对于粉磨到0.2 mm以下的晋城煤粉样品,不同粒径子样化学组成和矿物组成存在较大差异,其中,铁含量差异最明显。AFT和SEM结果都证明,45μm粒径煤粉子样煤灰熔融温度明显高于其他三种样品。Fact SageTM计算得到的液相量变化规律和AFT、SEM观察结果一致,说明煤灰熔融性随粒径变化是煤灰化学成分离析造成的,而SiO2-Al_2O_3-Fe_2O_3三元相图较好地解释了晋城煤煤灰熔融性随粒径变化机理。     

Kinetic Study of the Aggregation of Colloids Immersed in a Binary Mixture of Polymers

Summary: We consider an assembly of colloidal particles, which are immersed in a binary mixture of polymers. At temperatures close to the critical point of the free mixture, the fluctuations of the composition induce a critical Casimir force between colloids. This force naturally depends on their distance and it is responsible for the colloidal aggregation. In this paper, we propose to study the kinetics of such a transition leading colloids from a dispersed phase (gas) to a dense one (liquid). This kinetics is studied through the relaxation rate, which is a function of the transfer wave-vector.     

Use of modified enzymes for the solubilization/liquefaction of bituminous coal in a fluidized-bed reactor

Applied Biochemistry and Biotechnology - Biocatalysts allow the solubilization/liquefaction of coal at nearambient temperatures. This research has focused on the chemical modification of enzymes to...     

Experimental Study on Purification of Diesel Particulate Matter by Non-thermal Plasma Technology

In order to investigate the effects of non-thermal plasma (NTP) on diesel particulate matter (PM), an engine test bench was built up. An engine exhaust particle sizer (EEPS) was introduced to analyze the emission concentration and size distribution of PM and a thermo-gravimetric analyzer was used to analyze the effects of NTP on the composition of the particulate matter in the exhaust gas. The results show that the size distribution interval of the particle mass concentration falls behind that of the quantity concentration under various loads. When the diesel engine operating speed is 2400 rpm and the load is 25%, after NTP, the proportions of the nucleation mode particles and the accumulative mode particles exhibit a small fluctuation while the proportion of ultrafine particles decreases by 10% due to their large quantity concentration. Under the dual effect of DPF and NTP, the particle quantity concentration decreases by 98%. In order to investigate the effect of NTP on the composition of the PM, a thermo-gravimetric analysis of the particles obtained before and after NTP was carried out. The results show that the proportion of volatile matter falls by 16.05% and solid carbon accounts for an increase of 7.29%. NTP has the ability to improve reduction activity of particles and make particles easier to be oxidized at a lower temperature.     

Graft Copolymerization on to Cellulose Using Binary Mixture of Monomers

The graft copolymerization of acrylonitrile (AN) and ethyl acrylate (EA) comonomers onto cellulose has been carried out using ceric ammonium nitrate (CAN) as an initiator in the presence of nitric acid at 35±0.1°C. The addition of ethyl acrylate as comonomer has shown a significant effect on overall and individual graft copolymerization of acrylonitrile on cellulose. The graft yield (%G_Y) and other grafting parameters viz. true grafting (%G_T), graft conversion (%C_G), cellulose number (Ng) and frequency of grafting (G_F) were evaluated on varying the concentration of comonomers from 6.0–30.0×10^?1 mol dm^?3 and ceric (IV) ions concentration from 2.5–25×10^?3 mol dm^?3 at constant feed composition (f_AN 0.6) and constant concentration of nitric acid (7.5×10^?2 mol dm^?3) in the reaction mixture. The graft yield (%G_Y) and other grafting parameters were optimal at 15×10^?1 mol dm^?3 concentration of comonomers and at 10×10^?3 mol dm^?3 concentration of ceric ammonium nitrate. The graft yield (%G_Y) and composition of grafted chains (F_AN) was optimal at a feed composition (f_AN) of 0.6. The energy of activation (Ea) for graft copolymerization has been found to be 16 kJ mol^?1. The molecular weight (Mw) and molecular weight distribution (Mw/Mn) of grafted chains was determined by GPC and found to be optimum at 15×10^?1 mol dm^?3 concentration of comonomer in the reaction mixture. The composition of grafted chains (F_AN) determined by IR method was used to calculate the reactivity ratios of monomers, which has been found to be 0.62 (r₁) and 1.52 (r₂), respectively for acrylonitrile (AN) and ethyl acrylate (EA) monomers used for graft copolymerization. The energy of activation for decomposition of cellulose and grafted cellulose was determining by using different models based on constant and different rate (β) of heating. Considering experimental observations, the reaction steps for graft copolymerization were proposed.     

流化床快速制不定形活性焦脱除烟气中SO2的研究

利用大型流化床制得了适用于脱除烟道气中二氧化硫的不定形活性焦AC-A,并对其进行了特性分析,在固定床上考察了不同条件下脱除SO2的性能。与硫容相近的商业活性焦AC-B的脱硫性能对比,发现其脱硫性能较好。实验结果表明,在烟气中的二氧化硫的体积分数为0.05%~0.12%,反应温度为80 ℃～100 ℃,空速（GHSV）为1 200 h-1,O2的体积分数为6%,水蒸气为10%的情况下,活性焦AC-A保持SO2脱除率在90%以上达5 h。再生循环脱硫实验表明,活性焦AC-A具有良好的再生脱硫活性。     

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。