玉米秸秆循环流化床气化中试试验

玉米秸秆是农业生产过程中产生的剩余物,其热解气化是秸秆类生物质处理应用的重要选择方向。为此,采用循环流化床气化中试装置对玉米秸秆进行了气化试验,研究空气当量比ER、原料含水率对反应温度、气化燃气组分与热值、气化效率及燃气中的焦油含量等气化特性影响规律,并通过改变进料量试验得到了在不同负荷运行条件下的优化工作参数。结果表明：①随着ER的增大,循环流化床气化炉内的反应温度升高,气化燃气中的CO₂含量增加,焦油与CO含量及燃气热值降低,气化效率随ER的增大呈现先增大后减小趋势,较理想的ER为0.26,此时的气化效率达到70.2%、燃气热值为5.1MJ/m³;②原料含水率的增大降低了气化炉内的反应温度,当原料含水率在5%～15%之间逐渐增大时,燃气中的H₂含量、燃气热值及气化效率均有提升,当含水率由15%继续增大到25%过程中,燃气热值与气化效率均出现了快速下降;③根据气化炉额定进料量设计值,改变进料负荷在66%～120%范围内,调节ER在0.26～0.3时均可得到较好的运行工况,对应得到的燃气热值为4.8～5.1MJ/m³、气化效率为69%～72%。     

常压循环流化床气化技术

常压循环流化床气化技术方兆玕（中国氮肥工业协会大中氮分会北京市１０００２９）１常压循环流化床气化现状鲁奇公司为了把固体燃料（包括生物体、木材、褐煤、粘结性煤、焦炭、石油焦以及城市垃圾）转化成燃料气、城市煤气和合成气的粗气，长期进行了循环流化床（以下简...     

松木屑和褐煤流化床的共气化特性

在流化床上以空气-水蒸气为气化介质,对松木屑和褐煤的共气化特性进行了试验研究。在828～928 ℃范围内考察了生物质掺混比例、空气当量比（ER）和水蒸气-燃料比（S/F）对气化气成分、热值、碳转化率及气化效率的影响。结果表明,在生物质掺混比例为50%时,①随着ER值从0.2增加至0.35,CO2含量增加,CO、H2、CH4和CnHm含量减少,气化气热值、碳转换率、气化效率先增加后减少,在ER=0.26时达到最大;②在ER=0.26,S/F从0增加至0.44时,CO2含量增加,CO和H2含量先增加后减少,CH4和CnHm含量减少,气化气热值、碳转化率和气化效率先增加后减少。试验结果表明,在松木屑掺混比例为50%和褐煤共气化过程中,气化气热值最高可达7819 kJ/m3。     

循环流化床气化细粉灰熔融特性

因为流化床气化技术的优点非常多,主要包括：床层温度均匀、传热效率大、煤种范围广等等,所以被广泛用于煤气化中。不过流化床气化炉的操作温度比较低,使得气化细粉灰的含碳量较大。因此,为了有效加强碳的使用效率,减小环境污染,就对循环流化床气化细粉灰熔融特性展开了研究,借助测定仪、X射线衍射仪以及扫描电子显微镜等设备能够良好找到温度、气氛和残炭含量等因素对循环流化床气化细粉灰熔融特性的主要影响,给循环流化床技术的应用和发展带来很大的帮助。     

循环流化床燃烧及气化反应数学模型的概述

本文简要介绍了有关文献中循环流化术煤炭燃烧、气化及生物质气化的数学模型。根据中数学有所使用流体动力学模型的差异,将其分为鼓泡流化床数学模型,拟流体数学模型,区段数学模型,颗粒轨道数学模型及多维数学模型,并着重叙述了各模型所用到的流体动力学模型。     

预热空气当量比对循环流化床掺混煤泥预热燃烧的影响

煤泥灰含量大、颗粒细、热值低,煤泥的高效清洁燃烧是固废资源化利用的重要方式之一。采用煤粉流态化预热耦合循环流化床燃烧技术,在30 kW预热燃烧综合评价试验台上,控制煤泥掺混比、给料量、还原区当量比、二/三次风比例及过剩空气系数等参数不变,并借助煤气分析仪和烟气分析仪等测量仪器,开展了循环流化床烟煤掺混煤泥的预热燃烧试验。结果表明,循环流化床预热燃烧系统运行稳定可靠,预热温度800℃以上,预热燃料可持续稳定输送到循环流化床中;烟煤掺混高灰分的煤泥,循环灰量增加,循环流化床燃烧室温差小,温度均匀;预热空气当量比由0.36增至0.51时,预热器内温度增加,预热煤气中CO₂、HCN体积分数增加,CO、H₂、CH₄及NH₃体积分数降低,煤气热值由2.02 MJ/m³降至1.49 MJ/m³;且随着预热空气当量比的增加,循环流化床燃烧室沿程NO体积分数增加,CO体积分数底部高、上部低,NO_x排放量由172 mg/m³增至24...     

常压循环流化床(CFB)气化技术概况

介绍鲁奇公司的常压循环流化床（CFB）气化技术开发过程，以湿法为例介绍CFB生产合成气的基本流程。该工艺具有原料范围广，系统温度均匀，操作温度，压力低，氧耗低等特点，特别适合于日处理煤300-500t的装置。进行了UGI常压气化法，Texaco加压气化法和CFB气化法三种方法的工艺技术比较。     

CFB（循环流化床）气化技术简介

简要介绍循环流化床气化技术的工艺原理和工艺流程，并加以简单评价。     

废食用菌棒循环流化床气化试验

废菌棒是食用菌生产过程中产生的残余废弃物,其再利用对于资源节约与环境保护具有重要意义。本文采用循环流化床气化炉对废菌棒进行了气化试验,分别研究空气当量比、水蒸气配比对气化炉运行温度、气化燃气组分与热值、焦油含量、气化效率及碳转化率等气化特性的影响规律。结果表明：空气当量比由0.20增大至0.35时,循环流化床运行温度与碳转化率升高,气化燃气中的CO₂体积分数增大,CO与焦油含量及气化燃气热值下降,气化效率呈现先增大后减小的趋势;空气当量比为0.26时气化效率达到最大74.86%,此时燃气热值为5.59MJ/m³。以空气为主气化介质,采用水蒸气作为辅助气化剂,可以改善气化燃气品质,提升气化效率。当空气当量比为0.26、水蒸气配比为0.2时,废菌棒具有较好的空气-水蒸气气化特性,燃气热值与气化效率分别达到最大值6.14MJ/m³与83.73%。     

浅谈循环流化床气化数学模型研究

对循环流化床气化进行数值模拟研究可为气化炉设计、制造、运行提供指导。本文从热力学平衡模型和动力学模型两个方面综述了循环流化床气化数学模型。结果表明热力学平衡模型与实际气化过程相差甚远;双流体模型假设过于理想化,偏离实际;颗粒轨道模型计算量非常大,耗时很长;多维模型发展还不完善,需引入大量的经验公式;小室模型是模拟循环流化床气化较理想的模型。     

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％。     

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.     

循环流化床多联供试验台调节特性的试验研究

在一个循环流化床与移动床结合的多联供冷态试验台上,循环床与移动床之间用改进的气动分配阀控制循环物料的分配,提升管直径为400mm、高度为6000mm,移动床直径为476mm、高度为1200mm。进行了单回路运行和双回路同时运行的试验,对气动分配阀返料特性和系统压力分布进行了研究。在气动分配阀的返料临界压力范围内,在两侧存在压差的情况下,气动分配阀可以实现对循环物料在回路1和回路2之间分配的调节控制。试验结果为循环流化床多联供热态试验台的设计提供了一些经验。     

气液固循环流化床颗粒分布板实验研究

设计了用于气液固三相循环流化床换热器的固体颗粒分布板。采用功能强大的CCD图像采集分析系统,获得颗粒的分布和运动规律,考察了安装高度、运行参数等对分布板颗粒分布性能的影响。研究表明,分布板的安装高度、液体和气体流量、颗粒体积分数等对颗粒的速度和固含率分布有较大影响,得到了使固体颗粒在管束中分布效果较好的设计参数,以指导工程应用。     

Potential approaches to improve gasification of high water content biomass rich in cellulose in dual fluidized bed

Biomass containing water of 30-65 wt.% and rich in cellulose, such as various grounds of drinking materials and the lees of spirit and vinegar, is not suitable for biological digestion, and the thermal conversion approach has to be applied to its conversion into bioenergy. The authors have recently worked on converting such biomass into middle heating-value gas via dual fluidized bed gasification (DFBG) integrated with various process intensification technologies. This article is devoted to highlighting those technical ways, including the choice of the superior technical deployment for a DFBG system, the impregnation of Ca onto fuel in fuel drying, the integration of gas cleaning with fuel gasification via two-stage DFBG (T-DFBG), and the decoupling of fuel drying/pyrolysis and char gasification via the decoupled DFBG (D-DFBG). The attained results demonstrated that the superior deployment of bed combination for the DFBG should be a bubbling/turbulent fluidized bed gasifier integrated with a pneumatic riser combustor. In terms of improving efficiency of fuel conversion into combustible gas and suppressing tar generation during gasification, the impregnation of Ca onto fuel exhibited distinctively high upgrading effect, while both the T-DFBG and D-DFBG were also demonstrated to be effective to a certain degree.     

鼓泡流化床垃圾衍生燃料富氧气化

在鼓泡流化床上进行两种垃圾衍生燃料(RDF)的富氧气化试验,考察了RDF的热重特性并分析了气化温度、当量比及富氧浓度对气化特性的影响.结果表明:两种RDF均由纤维素及塑料类组分构成.随着温度由650℃升高至800℃,两种RDF产气的H₂、CO及CH₄浓度均逐渐增加,产气热值和气化效率同时提高.当量比增大时可燃组分浓度先略有增大后逐渐减小,但气体产率不断增大.RDF1及RDF2分别在当量比为0.22及0.27处达到最佳气化效率.富氧气化可有效改善气化品质,提升合成气热值,富氧浓度为45%时RDF1及RDF2合成气热值均达到最大,分别为8.6 MJ·m^-3及9.2 MJ·m^-3.     

A mathematical model of fluidized bed biomass gasification

A mathematical model of biomass gasification in a fluidized bed has been developed. It considers axial variations of concentrations and temperature in the bubble and emulsion phases. The mass balance involves instantaneous oxidation and equilibrium devolatilization of the biomass, kinetics of solid-gas gasification reactions as well as of gaseous phase reactions and interphase mass transfer and gas convection. The energy balance is solved locally for each vertical volume element, and globally on the reactor by iteration on the temperature at the bottom of the bed. Three parameters have been adjusted based on the experimental results: the heat transfer coefficient at the wall, the weighting of the kinetics of the water-gas shift reaction and the fraction of biomass carbon remaining as char after devolatilization. The model is used to simulate a pilot scale (50 kg/h) biomass gasifier, and its predictions compared to experimental measurements. The temperature and gaseous concentrations are estimated with good accuracy for the experiments using a wood feedstock, except for the concentration of hydrogen which is overestimated.