共查询到18条相似文献,搜索用时 171 毫秒
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CFB煤燃烧/热解双反应器中热解室对立管内气固流动特性的影响 总被引:4,自引:0,他引:4
考察了循环流化床煤燃烧/热解双反应器系统中热解室的存在对立管内的压力分布及气固流动状况的影响。提升管的内径100 mm、高6 m,立管的内径44 mm、高3 m,热解室的截面积200 mm×200 mm、高770 mm。结果表明,随着提升管内表观气速Ur的增加,有无热解室立管内均为负压差流动,负压差梯度随着Ur的增加而减小。有热解室时,热解室内要保持一定的料位高度,整个立管内固体颗粒的流动为负压差移动床流动;没有热解室时,立管内为稀相流动和移动床流动同时存在,立管内平衡料柱高度随Ur的增加而升高。随着循环量Gs的增加,两种类型的立管内负压差梯度均随之增大,也存在着流动形态的差别。循环量Gs的增加会引起立管内平衡料柱高度的降低。立管内气固相对滑移速度也随着循环量Gs的增加而增大。 相似文献
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采用高压热天平在终态温度为800℃,压力为0.1~5MPa,升温速率为5~25℃/min的实验条件下,对先锋、黄县褐煤和兖州烟煤在真实焦炉气气氛中共热解特性进行了系统的TG/DTG研究,主要考察了反应压力、升温速率对热解特性的影响,并与可比条件下加氢热解作比较。结果表明,压力和升温速率对热解有较大影响,压力升高热解总失重量增加,升温速率减慢有利于提高热解总转化率;压力与升温速率互相促进又互相制约共同影响热解特性。在给定较高压力下,减慢升温速率能明显提高热解总转化率;在慢速升温条件下,提高压力也能明显提高热解总转化率,通过降低升温速率可以实现在较低压力下达到甚至超过高压下的热解效果。与可比条件下的加氢热解相比,煤焦炉气共热解具有相近的热解特性,但总转化率略有降低且失重峰温向高温区移动。 相似文献
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实验采用TG151型高压热天平对不同热解压力和热解升温速率下煤焦炉气共热解半焦燃烧反应性进行了考察。主要考察半焦燃烧的特征参数如着火温度(Ti)、最大燃烧速率峰温(TM)和燃尽温度(Tf),最大燃烧速率(RM)以及燃尽时间(t),通过燃烧特征参数(燃尽时间t)和TG及DTG数据的相关动力学分析(Rf图)来描述半焦燃烧反应性能。结果表明,热解压力越高,其半焦燃烧反应性越差,在慢速升温情况下尤为明显;热解升温速率越快其半焦燃烧反应性越好,在较高压力下更为明显。先锋褐煤与焦炉气共热解半焦的反应活性与其加氢热解半焦的反应活性相当,但两者均略低于氮气氛下热解半焦的反应性。 相似文献
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按中山大学,辽宁大学等校编的《无机化学实验》58页图3-1的装置测定镁的当量,误差较大。产生误差的主要原因是:反应管(3)在塞上橡皮塞时,管内空气被压缩(气压增大),导致量气管(1)内水面下降和漏斗(2)内水面升高。因量气管至漏斗的各部分内径不等,使上述两水面升降程度不等。不等高的水柱压力不同,故用调节漏斗高度的方法,难以准确地调整反应管内外的气压根等,这既影响氢气产生前的体积初读数,又影 相似文献
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液态金属催化甲烷热解是一种高效生产氢气且无二氧化碳排放的新兴技术.本文开发了一个液态金属裂解反应器催化甲烷热解的数值模型,在实验室自主搭建的液态金属制氢平台上得到的实验数据与模型预测结果吻合良好.该模型是基于甲烷在气液界面发生的催化热解、气泡内部发生的非催化热解过程和气泡上升过程中的流动行为,耦合了催化和非催化反应动力学和流体力学所建立的.使用气体体积流速、压力、气体成分、温度和液态金属性质(密度、黏度和表面张力)预测气泡尺寸和熔体中的气含率.该模型较好地预测了液态铜铋合金(Cu0.45Bi0.55)催化甲烷热解实验中不同温度、不同甲烷进气流量和液态金属高度下的甲烷转化率,得到了催化甲烷热解过程中的气含率、表观气体速率和压力沿液态金属高度的分布.实验数据与模型预测结果的高度吻合证明了模型的可靠性,该模型未来将有助于反应器优化和氢产率提高. 相似文献
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木屑在鼓泡流化床和循环流化床中气化特性的对比研究 总被引:3,自引:0,他引:3
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。 相似文献
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在内径98mm的鼓泡浆态反应器内,考察了工艺参数对浸没表面与浆液间的传热系数的影响。浆态反应器轴向装有一个外径20mm,长120mm的测量传热膜系数用的铜制元件。为了模拟浆态FT合成反应系统,三相系统由N2、液体石蜡和石英砂(平均粒径53μm、110μm、180μm)或63μm以下的Fe2O3组成。工艺参数变化范围如下:表观气速0.005m/s~0.08m/s, 温度353K~453K, 压力0.1MPa~0.8MPa,固体的质量分数0~20%,初始液位高度625mm~1240mm。本研究使用单孔板、多孔板、烧结金属板三种气体分布器类型。结合实验数据,应用最小二乘法求得各个参数值,得到的无因次传热系数关联式为St=0.179(ReFr)-0.25Pr-0.66,相关指数0.98,最大偏差18%。该关联式可应用于气-液和粒径小于100μm的气-液-固体系。 相似文献
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压降法测量煤灰的初始粘结温度 总被引:2,自引:0,他引:2
在自制的实验装置上,以特定的压力将3 g~5 g的混合煤灰在内径8 mm~10 mm电熔刚玉管内压制成柱状,采用2 ℃/min~4 ℃/min的温升速率和10 mL/min~40 mL/min的空气流量,通过测量灰柱两端的压降随温度的变化关系,绘制压差温度曲线。曲线中最大压差点所对应的温度就是混合煤灰的初始粘结温度。利用此方法测量了IHI(Ishikawajima Harima Heavy Industries CO. LTD)循环流化床锅炉飞灰和秦皇岛北山热电厂循环流化床锅炉飞灰的初始粘结温度分别为900 ℃±10 ℃和1 300 ℃±10 ℃,从一个侧面解释了IHI循环流化床锅炉结焦严重,无法正常运行的原因。 相似文献
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针对90t RH精炼装置,以水力学模拟研究了吹气孔直径对真空循环精炼过程中钢液流动和混合特性的影响.模型和原型的相似比为15.模型吹气孔直径分别为0.8 mm和1.2 mm.结果表明,1.2 mm孔径下环流量和主要工艺参数间的关系为Ql Q80.26Du0.69Dd0.80;在给定的吹气量和插入管内径下,增大吹气孔直径并不显著改变精炼过程中钢液流动特征,环流量随吹气孔直径的增大而略有增大,其关系式为Ql=2.40Q 0.23gD0.72u D0.88d d0.13in;相应地,混合时间稍有缩短;0.8和1.2 mm孔径下,τm与搅拌能密度的关系分别为τm ε5和τm ε0.49. 相似文献
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ZHANG Kai * ZHAO Yu-long ZHANG Bi-jiang . State Key Lab of Heavy Oil Processing Faculty of Chemical Science Engineering University of Petroleum Beijing P. R. China . Institute of Coal Chemistry Chinese Academy of Sciences POBox Taiyuan P. R. China . Department of Chemical Engineering University College London London WCE JE UK 《高等学校化学研究》2004,20(4):478-482
IntroductionBubble column( BC) and slurry bubble column( SBC) reactors have emerged as one of the mostpromising devices in chemical,biochemical and en-vironmental engineering operations because of theirsimple construction,isothermal conditions,highheat and mass transfer rates,and on- line catalystaddition and withdrawal[1_ 4] .The utilization of ta-pered slurry bubble column( TSBC) reactorshas re-cently received much attention ofsome scholars andscientists who are engaged in biochemical rea… 相似文献
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Miloslav Hartman Karel Svoboda Michael Poho?ely Michal ?yc Michal Jeremi��? 《Chemical Papers》2013,67(2):164-172
Results of an experimental study on the rate of attrition of lime catalyst/sorbent in a high-temperature, turbulent fluidized bed with quartz sand are presented. Batch measurements were conducted at 850°C in an electrically heated gasification reactor of the inner diameter of 5.1 cm with three samples of high-grade dolomitic lime of the particle size 450 ??m, 715 ??m, and 1060 ??m, respectively. In addition to the influence of the particle size, the effect of operating (elapsed) time was investigated at different superficial gas velocities. Assuming that the attrition rate decreases exponentially with time, a simple mechanistic model, enabling the correlation of the measured experimental data, was developed. The course of the lime particles attrition is described as a function of the elapsed time, excess gas velocity, and particle size. The presented approach and the results might be applicable for the attrition of high-grade dolomitic lime, particularly in fluidized gasification of biomass. 相似文献
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JINHai-bo YANGSuo-he ZHANGTong-wang TONGZe-min 《高等学校化学研究》2004,20(4):462-465
Gas holdups of large bubbles and small bubbles were measured by means of dynamic gas disengagement approach in the pressured bubble column with a diameter of 0. 3 m and a height of 6.6 m. The effects of su-perficial gas velocity, liquid surface tension, liquid viscosity and system pressure on gas holdups of small bub-bles and large bubbles were investigated. The holdup of large bubbles increases and the holdup of small bub-bles decreases with an increase of liquid viscosity. Meanwhile, the holdup of large bubbles decreases with in-creasing the system pressure. A correlation for the holdup of small bubbles was obtained from the experimen-tal data. 相似文献
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In this paper,an axial dispersion mathematical model is developed to simulate a three-phase slurry bubble column reactor for direct synthesis of dimethyl ether(DME) from syngas.This large-scale reactor is modeled using mass and energy balances,catalyst sedimentation andsingle-bubble as well as two-bubbles class flow hydrodynamics.A comparison between the two hydrodynamic models through pilot plantexperimental data from the literature shows that heterogeneous two-bubbles flow model is in better agreement with the experimental data thanhomogeneous single-bubble gas flow model.Also,by investigating the heterogeneous gas flow and axial dispersion model for small bubblesas well as the large bubbles and slurry(i.e.including paraffins and the catalyst) phase,the temperature profile along the reactor is obtained.Acomparison between isothermal and non-isothermal reactors reveals no obvious performance difference between them.The optimum values ofreactor diameter and height were obtained at 7 m and 50 m,respectively.The effects of operating variables on the axial catalyst distribution,DME productivity and CO conversion are also investigated in this research. 相似文献
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C. C. Dantas R. Narain V. A. dos Santos A. C. B. A. Melo 《Journal of Radioanalytical and Nuclear Chemistry》2006,269(2):425-428
Summary The axial and radial distribution of the catalyst concentration, in the riser of an EMC - experimental cold model of a fluid
catalytic cracking type unit, was measured by gamma-absorption. The solid concentration in the circulating fluidized bed was
determined by measurements with a 241Am gamma-source and a NaI(Tl) detector. The operation, instrumental measurements and data acquisition system of the cold unit
were automated. The catalyst concentration measurements were carried out in static experiments and in the circulating fluidized
bed. A calibration of the distribution concentration was made with experimental data from gas velocity and pressure drop along
the riser that gave the best multi-regression model. A spatial resolution of 5.0 . 10-3 m by scanning the riser and a catalyst density resolution of 5.0±0.8 kg/m3 were obtained. The axial catalyst concentration distribution, in the 5-13 kg/m 3 interval, showed a predicted pattern according to the literature. The radial distribution was in an annular configuration
for this diluted catalyst concentration. 相似文献