昭通褐煤气化扩大试验研究

针对昭通褐煤的特点 ,在气化煤量为 0 .3t/h的焦载热流化床气化扩大试验装置上进行了试验研究 .研究结果表明 ,煤气中焦油量很小 ,有利于煤气生产的后期处理 ;与移动床气化和普通流化床气化相比 ,煤气热值和气化产率都有较大增加 ,煤气热值已接近城市煤气的要求 ;加大气化煤量可增加提升段燃烧的易燃成分 ,从而提高了燃烧温度和气化温度 ;气化煤量的变化对褐煤气化产率和产量的影响较大 .对于开发昭通褐煤资源来说 ,采用本工艺技术生产城市煤气是一个较佳的方案 .     

Convective heat transfer and solid conversion of reacting particles in a copper(II) chloride fluidized bed

This paper develops a predictive model of convective heat transfer and conversion of cupric chloride particles in a fluidized bed reactor of a copper–chlorine (Cu–Cl) cycle of thermochemical hydrogen production. The hydrolysis reaction of particles in the fluidized bed is endothermic and it requires excess steam for complete conversion of cupric chloride solid. The excess steam supply may be used for partial heat supply to the endothermic reaction, and also to avoid defluidization in the bed. To avoid defluidization, the change of gas flow in the bed due to the reaction should be minimized at a given operating condition. The model predicts the maximum possible steam inlet temperature, steam conversion, amount of partial heat supply, and also gas flow rates through the bed to avoid defluidization. The new model presents significant new insight by analyzing the hydrodynamic and mass transport processes, considering the equilibrium limitation on the conversion of cupric chloride solid. The model results indicate that the chemical reaction requires a high mole ratio of steam for complete conversion of cupric chloride particles. The maximum steam conversion is limited by temperature, pressure, and the presence of hydrogen chloride gas. The maximum conversion of steam at 400 °C is 3.75% and it requires excess steam of 12.8 moles per unit mole of cupric chloride solid for complete conversion of solid. The heat supply by steam for the reaction, as well as raising the solid feed to the reaction temperature, varies with reaction temperature. The paper also adds significant new insight by analyzing the steam flow requirement in terms of temperature, conversion rate, and quality of fluidization. Additional new results are presented and applications discussed for the Cu–Cl cycle of nuclear hydrogen production.     

Fundamentals of coal topping gasification: Characterization of pyrolysis topping in a fluidized bed reactor

Coal topping gasification refers to a process that extracts the volatiles contained in coal into gas and tar rich in chemical structures in advance of gasification. The technology can be implemented in a reactor system coupling a fluidized bed pyrolyzer and a transport bed gasifier in which coal is first pyrolyzed in the fluidized bed before being forwarded into the transport bed for gasification. The present article is devoted to investigating the pyrolysis of lignite and bituminite in a fluidized bed reactor. The results showed that the highest tar yield appeared at 823 to 923 K for both coals. When coal ash from CFB boiler was used as the bed material, obvious decreases in the yields of tar and pyrolysis gas were observed. Pyrolysis in a reaction atmosphere simulating the pyrolysis gas composition of coal resulted in a higher production of tar. Under the conditions of using CFB boiler ash as the bed material and the simulated pyrolysis gas as the reaction atmosphere, the tar yields for pyrolytic topping in a fluidized bed reactor was about 11.4 wt.% for bituminite and 6.5 wt.% for lignite in dry ash-free coal base.     

基于CoFe2O4载氧体的生物质化学链气化反应特性

在热重分析仪和固定床反应器上对基于CoFe₂O₄载氧体的生物质化学链气化反应特性进行了研究，考察了载氧体与生物质质量比、水蒸气、反应温度对生物质化学链气化反应特性的影响，同时也对载氧体的循环反应性能进行了研究。通过XRD及SEM对新制备的和反应后的载氧体进行了表征。热重结果表明：CoFe₂O₄能够提供晶格氧，有效促进生物质气化。当CoFe₂O₄与生物质质量比为0.8，水蒸气体积分数为50%，温度为900 ℃时，气化反应效果最好。5次循环反应后，仍能获得较高品质的合成气，载氧体能够循环再生且未出现明显烧结团聚。     

维多利亚褐煤干燥气化技术进展

为实现褐煤清洁高效利用,在分析维多利亚褐煤煤质特性的基础上,综述了国外先进的褐煤干燥及气化技术。褐煤干燥工艺主要有蒸发干燥和非蒸发脱水2种,重点分析了磨煤机干燥工艺、褐煤浆生产高致密褐煤球干燥工艺、回转蒸汽管干燥工艺和机械热挤压脱水工艺的工艺流程和应用现状,其中磨煤机干燥工艺和回转蒸汽管干燥工艺技术比较成熟,工业应用较多。论述了维多利亚褐煤气化工艺中的褐煤集成干燥气化工艺和增压流化床气化工艺,提出若将褐煤集成干燥气化工艺中的空气气化改为富氧或纯氧气化,并通入一定比例水蒸气,该工艺有望应用于中国煤化工领域,生产化工合成原料气,为中国褐煤高效洁净利用提供途径。     

CO2气氛下准东煤化学链燃烧特性研究

我国准东煤储量丰富,钠含量高。以高钠准东煤为燃料,CO₂为气化介质,铁矿石为载氧体,基于鼓泡流化床反应器开展准东煤化学链燃烧特性的实验研究,考察了煤粒径、温度、流化风速和煤焦粒径对煤及煤焦化学链燃烧过程中可燃气体逃逸规律的影响;同时研究了煤中矿物质对煤焦气化过程的影响。结果表明,在基于鼓泡流化床实施的煤化学链燃烧过程中,由于煤颗粒和载氧体床料流化特性差异大,存在离析现象;离析影响煤化学链燃烧过程中挥发分和焦炭的转化;较高流化风速可显著增强载氧体与煤/焦炭颗粒的混合,有效改善离析对可燃气体转化的影响,降低可燃气体逃逸,并加快焦炭气化速率;煤焦中的矿物质能够维持煤焦较快的气化速率。     

Gasification characteristics of combustible wastes in a 5 ton/day fixed bed gasifier

The gasification characteristics of combustible wastes were determined in a 5 ton/day fixed bed gasifier (1.2 m I.D. and 2.8m high). The fixed bed gasifier consisted of air compressor, oxygen tank, MFC, fixed bed gasifier, cyclone, heat exchanger, solid/gas separator, water fluidized bed reactor and blower. To capture soot or unburned carbon from the gasification reaction, solid/gas separator and water fluidized bed were used. The experiments with 10–50 hours of operation were carried out to determine the effects of bed temperature, solid/oxygen ratio and oxidant on the gas composition, calorific value and carbon conversion. The calorific values of the produced gas decreased with an increase of bed temperature because combustion reaction happened more actively. The gas composition of partial oxidation of woodchip is CO: 34.4%, H₂: 10.7%, CH₄: 6.0%, CO₂: 48.9% and that of RPF is CO: 33.9%, H₂: 26.1%, CH₄: 10.7%, CO₂: 29.2%. The average calorific values of produced gas were about 1,933 kcal/Nm³, 2,863 kcal/Nm³, respectively. The maximum calorific values were 3,100 kcal/Nm³ at RPF/oxygen ratio: 7     

Experimental and mechanistic study on chemical looping combustion of caking coal

Under high-temperature batch fluidized bed conditions and by employing Juye coal as the raw material,the present study determined the effects of the bed material,temperature,OC/C ratio,steam flow and oxygen carrier cycle on the chemical looping combustion of coal.In addition,the variations taking place in the surface functional groups of coal under different reaction times were investigated,and the varia-tions achieved by the gas released under the pyrolysis and combustion of Juye coal were analyzed.As revealed from the results,the carbon conversion ratio and rate were elevated significantly,and the vol-ume fraction of the outlet CO2 remained more than 92％ under the oxygen carriers.The optimized reac-tion conditions to achieve the chemical looping combustion of Juye coal consisted of a temperature of 900℃,an OC/C ratio of 2,as well as a steam flow rate of 0.5 g·min-1.When the coal was undergoing the chemical looping combustion,volatiles primarily originated from the pyrolysis of aliphatic-CH3 and-CH2,and CO and H2 were largely generated from the gasification of aromatic carbon.In the CLC process,H2O and CO2 began to separate out at 270 ℃,CH4 and tar began to precipitate at 370 ℃,and the amount of CO2 was continuously elevated with the rise of the temperature.     

生物质催化气化实验研究

在常压流化床上进行了生物质在水蒸气条件下的实验研究。实验装置主体由常压流化床反应器和固定床催化裂解反应器组合而成。生物质原料为木屑,焦油裂解催化剂分别选用煅烧白云石和镍基重整催化剂。实验结果表明,H2/CO(H/C)的摩尔比随着气化温度、水蒸气质量/生物质质量（S/B）的升高迅速增加,但催化裂解温度变化对H/C的影响较小。另外,在催化裂解反应器中使用催化剂种类不同,H/C也不同。本文采用两段催化裂解,一段催化剂采用煅烧白云石,二段采用镍基催化剂,焦油裂解率达到96.70％。采用两段催化裂解,不但可以提高焦油的裂解率,增加了H2和CO收率,净化生物质裂解气,而且可以防止镍基重整催化剂失活,延长其使用寿命。     

鼓泡流化床内高灰煤气化过程的颗粒尺度特性研究

基于多相流体质点网格方法(MP-PIC)对高灰煤在三维鼓泡流化床气化过程进行了数值模拟研究。在欧拉-拉格朗日框架下将气相和固相分别视作连续介质和离散相处理。首先,将模拟得到的出口处气体组分结果与实验数据进行对比,实验数据与模拟结果具有良好的一致性。其次,研究了煤颗粒在气化炉内的温度、传热系数、速度和停留时间,从颗粒尺度揭示了鼓泡流化床气化炉内的颗粒分布特性和气固流动特征。结果表明:在气化炉入口附近煤颗粒与床层温差最大,传热系数最大;由于流化床内强非线性的气固流动,床中煤温度和传热系数的空间分布不均匀;煤颗粒和床料的瞬时速度具有稳定的波动幅度,其中垂直方向速度波动最明显,且煤颗粒的瞬时速度比床料的瞬时速度略大;由于颗粒间的剧烈碰撞,延长了煤颗粒停留时间。此外,对鼓泡流化床中煤气化过程颗粒尺度的研究,有助于深入了解固体颗粒的流动行为以及气固相相互作用特性,对鼓泡流化床反应器的设计优化具有重要意义。     

废弃咖啡渣化学链气化反应特性

利用溶胶-凝胶法制备了以Fe₂O₃为活性组分,天然凹凸棒土(ATP)为惰性载体,KNO₃修饰的Fe4ATP6K1铁基复合载氧体。在高温流化床中考察了反应温度、水蒸气流量和O/C摩尔比对咖啡渣化学链气化过程的影响。结果表明,与以石英砂为床料的咖啡渣气化相比,以Fe4ATP6K1载氧体为床料的咖啡渣化学链气化对应的碳转化率由71.38%提高到86.25%。咖啡渣化学链气化的较优操作条件为:反应温度900℃、水蒸气量0.23 g·min^-1、O/C摩尔比1;在此操作条件下,合成气产量达到1.30 m³·kg^-1,氢气产量达到83.79 g·kg^-1,氢气的平均浓度达到52.75%。通过X射线衍射(XRD)、扫描电镜-能谱(SEM-EDS)对900℃反应前后的Fe4ATP6K1进行表征,发现Fe相、K相、Si相可以发生相互作用,K以KFeSi₃O₈的形式存在于载氧体中,并且K在反应过程中有少量流失。20次氧化/还原过程中,铁基复合载氧体Fe4ATP6K1表现出较好的循环性能,碳转化率和冷煤气效率均保持在75%以上,各气体的平均浓度较稳定。     

串行流化床煤气化试验

针对串行流化床煤气化技术特点,以水蒸气为气化剂,在串行流化床试验装置上进行煤气化特性的试验研究,考察了气化反应器温度、蒸汽煤比对煤气组成、热值、冷煤气效率和碳转化率的影响。结果表明,燃烧反应器内燃烧烟气不会串混至气化反应器,该煤气化技术能够稳定连续地从气化反应器获得不含N₂的高品质合成气。随着气化反应器温度的升高、蒸汽煤比的增加,煤气热值和冷煤气效率均会提高,但对碳转化率影响有所不同。在试验阶段获得的最高煤气热值为6.9 MJ•m^-3,冷煤气效率为68％,碳转化率为92％。     

Modeling and experimental studies on single particle coal devolatilization and residual char combustion in fluidized bed

Single particle devolatilization followed by combustion of the residual coal char particle has been analyzed in a batch-fluidized bed. The kinetic scheme with distributed activation energy is used for coal devolatilization while multiple chemical reactions with volume reaction mechanism are considered for residual char combustion. Both the models couple kinetics with heat transfer. Finite Volume Method (FVM) is employed to solve fully transient partial differential equations coupled with reaction kinetics. The devolatilization model is used to predict the devolatilization time along with residual mass and particle temperature, while the combined devolatilization and char combustion model is used to predict the overall mass loss and temperature profile of coal. The computed results are compared with the experimental results of the present authors for combustion of Indian sub-bituminous coal (15% ash) in a fluidized bed combustor as well as with published experimental results for coal with low ash high volatile matter. The effects of various operating parameters like bed temperature, oxygen mole fraction in bulk phase on devolatilization time and burn-out time of coal particle in bubbling fluidized bed have been examined through simulation.     

流化床法制备硅化镁的工艺研究

在一定的温度,高纯氢气氛围下,以硅粉、镁粉为原料,于流化床反应器中制备硅化镁.考察了硅粉与镁粉粒度、反应温度、反应时间、不同原料配比以及载气流量对反应的影响.实验结果表明,实验最佳条件是镁粉与硅粉摩尔比为2.05∶1、镁粉和硅粉的粒度在100～160目且粒度相差20目以内、反应温度570℃、反应时间2.0h、载气流量为3.0～5.0 L/min.在此实验条件下,硅化镁的质量含量≥98.3％.     

固体热载体法褐煤热解过程中的传质传热特性

为揭示在固定床反应器中固体热载体法快速热解褐煤工艺过程中的热、质传递机理,建立了固体热载体法褐煤热解过程中的传质传热模型。模型包括球型颗粒的一维非稳态导热方程和基于分布活化能模型的动力学模块,分别采用有限容积法与Matlab软件中遗传算法工具箱对二者进行数值计算。通过呼伦贝尔褐煤热重实验数据与温度测定实验数据分别验证了预测的动力学参数及颗粒传热模型结果。研究发现,热、质变化在固体热载体法褐煤热解工艺中呈现复杂的耦合特性。此外,考察了在不同初始温度、热载体进料比与煤颗粒半径条件下,褐煤在热解过程中颗粒内部温度场在径向上随时间的变化规律,并分析了产物释放速率与温度场的关联性,结果表明热历程改变是工艺条件对热解产物分布造成影响的根本原因。     

KBR传输集成气式化 技术综述

传输集成式气化（TRIG）工艺由美国KBR公s-J开发，是一种先进的加压循环流化床气化技术。介绍了TRIG气4E．-z-艺的开发背景、工艺流程、技术特点以及气化炉结构形式；分析了TRIG示范装置的气化试验运行概况和生产工艺数据；结果表明，TRIG气化工艺特别适宜于气化褐煤等低阶煤种，具有广阔的应用前景。     

SES煤气化技术及其在国内的应用

SES煤气化技术是在传统U-Gas单段循环流化床粉煤气化技术的基础上进一步开发而成。简介了我国已引进的9种国外煤气化技术的工艺特点和应用概况;重点论述了U-Gas煤气化技术的气化原理、工艺流程、操作指标和技术优势;介绍了SES煤气化技术在国内能源综合利用和洁净煤气化项目的应用实例。结果表明,该技术的新型流化床反应器不仅能够气化占我国煤炭储量17%的难以气化的褐煤,而且能够高效地气化洗煤过程中产生的煤矸石等副产品,对我国中小型氮肥企业原料路线的技术改造具有现实意义。     

Steam‐air blown bubbling fluidized bed biomass gasification (BFBBG): Multi‐scale models and experimental validation

During fluidized bed biomass gasification, complex gas‐solid mixing patterns and numerous chemical and physical phenomena make identification of optimal operating conditions challenging. In this work, a parametric experimental campaign was carried out alongside the development of a coupled reactor network model which successfully integrates the individually validated sub‐models to predict steady‐state reactor performance metrics and outputs. The experiments utilized an integrated gasification system consisting of an externally‐heated, bench‐scale, 4‐in., 5 kWth, fluidized bed steam/air blown gasifier fed with woody biomass equipped with a molecular beam mass spectrometer to directly measure tar species. The operating temperature (750–850°C) and air/fuel equivalence ratio (ER = 0–0.157) were independently varied to isolate their effects. Elevating temperature is shown to improve the char gasification rate and reduce tar concentrations. Air strongly impacts the composition of tar, accelerating the conversion of lighter polycyclic‐aromatic hydrocarbons into soot precursors, while also improving the overall carbon conversion. © 2016 American Institute of Chemical Engineers AIChE J, 63: 1543–1565, 2017     

In situ gasification and CO2 separation using chemical looping with a Cu-based oxygen carrier: Performance with bituminous coals

This paper is concerned with the chemical looping combustion of coal in a technique whereby the fuel is gasified in situ using CO₂ in the presence of a batch of supported copper oxide (the “oxygen carrier”) in a single reactor. As the metal oxide becomes depleted, the feed of fuel is discontinued, the inventory of fuel is reduced by further gasification and then the contents are re-oxidised by the admission of air to the reactor, to begin the cycle again. A catalyst support, impregnated with a saturated solution of copper and aluminium nitrates, acted as a durable oxygen carrier over numerous cycles of reduction and oxidation, using air as the oxidant. Two bituminous coals (Taldinskaya, Russia, and Illinois No. 5, USA) were investigated and compared with a lignite (Hambach, Germany). The lignite was highly reactive and was gasified completely by 15 mol% CO₂ in N₂ at 1203 K and 1 bar, so that there was no build up of char in the bed. The bituminous coals produced chars much less reactive than the lignite char, so that there was a steady accumulation of char in the bed with number of cycles, with the degree of accumulation being dependent on the reactivity of the char. Since the kinetics of gasification by CO₂ of the chars from either bituminous coal were slow, their rates were controlled by intrinsic chemical kinetics and were not affected by the ability of the oxygen carrier to alter the rates of external mass transfer when gasification is rapid. However, it is likely that rates of gasification in the presence of the carrier are still larger than in its absence, owing to the overall lower [CO] present in the bulk of the fluidised bed during chemical looping. At the temperature used, the carrier was cycling between Cu and Cu₂O, since CuO is only stable if the partial pressure of O₂ exceeds 0.03 bar at 1203 K. The CuO decomposes to Cu₂O and O₂ relatively rapidly at these temperatures, once the oxygen concentration is effectively zero. It was impossible to ascertain in our experiments whether the oxygen so generated, after the switching of the air for nitrogen before the start of the succeeding cycle of gasification, made any substantial difference to the reactivity of the char present in the bed. The rate of oxidation of the carrier was found to be much more rapid than the rate of oxidation of the inventory of char. This allows a preferential oxidation of the carrier and most likely accounts for why progressively less CO and CO₂ is produced during successive cycles with short periods of oxidation: the increasingly reduced carrier reacts more rapidly than the char. There was no obvious impact from the sulphur contained in the fuels, but longer-term testing is needed. No agglomeration between the carrier particles and the ash was observed, despite the high temperatures during oxidation.     

微型流化床中萘裂解生成小分子气体的反应动力学研究

气化是煤、生物质以及其他含碳燃料高值化利用的有效途径之一。为了考察气化过程中焦油的反应转化特性,选取萘作为焦油模型化合物,以流化催化裂化（fluid catalytic cracking,FCC）催化剂及褐煤热解焦作为接触裂解载体,利用微型流化床考察流化条件下萘催化裂解反应规律,并采用Friedman法和积分法计算萘裂解生成CH₄和H₂等典型气体组分的动力学参数。结果表明,FCC催化剂与褐煤焦均对萘裂解有明显的催化效果,褐煤焦用于萘裂解的反应活化能整体数值低于FCC催化剂。FCC催化剂裂解萘生成H₂符合三维扩散（球形对称）模型,生成CH₄符合成核与生长（n=2/3）模型。相应地,褐煤焦裂解萘反应生成H₂和CH₄分别采用收缩几何形状（圆柱形对称）和三维扩散（圆柱形对称）具有较好的拟合度。