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％。     

基于Aspen Plus的Shell气流床工业气化炉模拟

基于Aspen Plus软件的Gibbs自由能最小化法,本文建立了煤粉在Shell气流床中的气化模型。该模型预测气化温度和煤气组成,与文献试验结果吻合良好。利用Aspen Plus的灵敏度分析模块研究了氧煤比、氧气体积分数和氧气预热温度对气化结果的影响,并进行了正交模拟计算,研究了以上3种因素共同作用的结果。结果表明：氧煤比增加使碳转化率升高,冷煤气效率先升高后降低,并在氧煤比为0.9kg/kg时取得最大值77.72%;氧气体积分数增加使煤气热值、碳转化率和冷煤气效率升高,氧煤比为0.8kg/kg且氧气体积分数为50%时,冷煤气效率可达82.6%;氧气预热温度增加使碳转化率、冷煤气效率升高,氧煤比为0.8kg/kg且氧气预热温度为600℃时,冷煤气效率可达82%。通过正交模拟计算综合分析,氧煤比对冷煤气效率和碳转化率的影响作用占首位,氧气体积分数对煤气热值、有效气体积分数、煤气产率的影响作用占首位,氧气预热温度对煤气化指标影响较小。在实验范围内,当氧煤比0.8kg/kg、氧气体积分数100%、氧气预热温度300℃时的煤气热值达到最大值3011kcal/m³;当氧煤比为0.8kg/kg、氧气体积分数60%~100%、氧气预热温度300~500℃时的冷煤气效率达到最大值83.46%。     

基于Aspen Plus的循环流化床工业气化炉模拟

循环流化床煤气化炉在工业应用过程中,由于试验煤种及操作条件的多样性,通过试验法优化操作过程所需周期较长、成本较大。因此以大量工程数据为边界条件,基于Gibbs自由能最小化原理,利用Aspen Plus对气化过程进行模拟,通过灵敏度分析,研究了单因素氧煤比、蒸汽煤比、气化压力、空气/蒸汽预热温度变化对气化指标的影响;并运用正交实验,研究了以上4种因素共同作用的结果。研究结果表明:氧煤比增加使有效气(CO+H_2)含量、冷煤气效率先增加再减小,并在0.45~0.50kg/kg时取得最大值;蒸汽煤比增加使煤气热值和气化温度减小,对有效气含量基本没有影响;气化压力增加使煤气热值和气化温度增加;空气/蒸汽预热温度增加使气化温度、有效气含量、冷煤气效率增加,煤气热值减小。通过正交实验综合分析,氧煤比和空气/蒸汽预热温度对气化指标的影响较为显著,两者对气化指标的影响趋势基本一致;蒸汽煤比主要影响煤气热值,而气化压力主要影响比氧耗,对其他指标影响较小。     

流化床煤气化试验研究

为研究温度和煤的煤焦反应性对流化床煤气化特性的影响,在小型电加热鼓泡床试验装置上,对4种高灰劣质粉煤——石沟驿煤、大塘煤、洋江煤和玉带煤进行空气为气化剂的煤气化试验研究。研究结果表明:随着温度的升高,各煤种气化得到冷煤气的热值、产气率、冷煤气效率和碳转化率均升高,在1 000℃时,石沟驿煤气化得到煤气的热值、产气率、冷煤气效率和碳转化率分别达到4.65 MJ/m3,2.21 m3/kg,47.8%和65.7%;4种煤的煤焦反应性均较差,其中石沟驿煤相对较高,其他煤的煤焦反应性低且相近;在相同温度水平下,气化得到煤气有效成分和热值与煤的煤焦反应性成正相关关系,煤的煤焦反应性最高的石沟驿煤气化得到的冷煤气的有效成分、热值均明显高于其他煤种。     

循环流化床煤气化高温助燃的设计与应用

科达洁能清洁煤气化系统采用高温煤气预热混合气化剂,高温助燃气化剂温度可达到750℃,有效降低了煤耗,提高了煤气热值和气化效率。     

大粒度煤块气化特性研究

分别以H_2O(g)和CO_2为气化剂,采用自制的煤炭地下气化模拟实验装置完成大颗粒鹤壁烟煤和晋城无烟煤的气化模拟实验,用便携式气体分析仪对煤气组分进行测定,并用SEM分析气化后的半焦,考察了气化剂种类、气化温度和气化时间对2种煤气化反应特性的影响。结果表明:CO_2为气化剂时,反应温度越高,煤气中CO,H_2,CH_4含量越多,煤气热值也越高;以H_2O(g)为气化剂时,H_2含量随着反应温度升高增大,CO含量则先增大后降低,CH4明显降低。气化温度1 000℃时煤气热值最高,鹤壁煤和晋城煤热值分别达13.12 MJ/m~3和11.25 MJ/m~3;气化进行30 min时反应速率最大,60 min时热值最高;相同气化剂条件下鹤壁烟煤的煤气热值高于晋城无烟煤煤气;相同煤种条件下H_2O(g)为气化剂时的煤气热值高于CO_2。     

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...     

神木烟煤流态化预热中煤气生成特性

预热燃烧具有燃料适应性广、负荷调节快及污染物排放低等优势，是一种新型的高效清洁燃烧技术。其中，煤粉流态化预热后产生的预热煤气既能反映预热过程中煤粉的改性程度，又对后续燃烧效率及NO_x排放有重要影响。因此，煤粉流态化预热后产生的预热煤气是控制燃料转化及低NO_x排放的关键。基于煤粉流态化预热转化过程，在温度可控的千瓦级煤粉预热燃烧试验平台上，研究了预热温度、循环流化床空气当量比、煤粉粒径对预热煤气生成特性的影响。结果表明，850～950℃,随预热温度升高，热解反应及气化反应增强，煤气中CO₂体积分数下降，CO体积分数增加，H₂体积分数先增加后不变，CH₄体积分数则先增加后减小，煤气品质改善，热值由2.86 MJ/m³增至3.61 MJ/m³;循环流化床空气当量比从0.3增至0.5时，氧化反应增强，煤气中CO₂体积分数增加，CO、H₂、CH₄体积分数降低，煤气热值由3.44 ...     

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.     

以CO_2和H_2O为气化剂的煤焦气化模拟

基于整体煤气化联合循环和燃料电池发电技术,利用固体氧化物燃料电池产生的高温、高纯度CO2与H2O作为煤焦气化的气化剂,运用Aspen Plus模拟软件平台基于Gibbs自由能最小化方法对煤焦的H2O-CO2共气化反应进行了模拟计算。考察了O2流量、H2O流量、CO2流量、预热温度、操作压力、反应温度对气化反应合成气组成和煤气低位发热量的影响。结果显示:通过调节O2流量,得出O2的最佳流量为20 kg/h,此时反应温度和合成气低位热值处于最高值;分别增加水蒸气流量和CO2流量都使反应温度降低,且使反应活性降低导致合成气低位热值降低,所以合理控制水蒸气和CO2流量至关重要;降低操作压力会降低合成气的低位热值,但相对于物料流量改变,影响较小;CO2预热对煤气低位发热量的影响要小于O2的预热效果。     

Reasearch on the main factors for changes in pressure based on turbulent circulating fluidized bed coal gasification technology

High temperature preheated air and steam as gasifying agent and coal gasification was performed in a pressurized turbulent circulating fluidized bed (CFB) gasification pilot plant to investigate the pressurized gasification process and estimate its potential. Within the scope of this paper this test facility as well as its operation behavior was described. Furthermore, the parameter pressure has been investigated regarding its influence on the syngas composition and was presented and discussed in the following. The results show that the gasification quality is improved at higher pressure because of the better fluidization in the reactor. Coal gasification at a higher pressure shows advantages in lower heat value and carbon conversion. With the gasifier pressure increased from 0.1MPa to 0.3MPa, the gas heating value is increased by 15%. Increasing the gasifier pressure would increase the carbon conversion from 57.52% to 76.76%. Also, the dry gas yield and efficiency of cold gas increase little with the increase of the gasifier pressure. The operating parameter of pressure exists at optimum operating range for this specific CFB coal gasification process.     

Experiment and mathematical modeling of a bench-scale circulating fluidized bed gasifier

The gasification of two different coals and chars with CO₂ and CO₂/O₂ mixture in a 48-mm-i.d. circulating fluidized bed (CFB) gasifier is investigated. The effects of operation condition on gas composition, carbon conversion and gasification efficiency were studied. A simple CFB coal gasification district mathematical model has been set up. The effects of coal type and CFB operating conditions on CFB coal gasification are discussed based on the CFB gasification test and model simulation. The main operation parameters in CFB gasification system are coal type, gas superficial velocity, circulating rate of solids and reaction temperature. It is found that CO concentration and carbon conversion increase with increasing solids circulating rate and decreasing gas velocity due to the increase in gas residence time and solids holdup in the CFB. The carbon conversion increases with increasing temperature and O₂ concentration in the inlet gas. The experimental results prove that the CFB gasifier works well for high volatile, high reactivity coal.     

射流预氧化流化床气化炉中黏结性煤的反应特性

针对现有流化床气化技术难以处理黏结性、高含灰洗中煤的问题, 中国科学院过程工程研究所开发了可处理黏结性碎煤的射流预氧化流化床气化技术, 该技术利用含氧气体将煤颗粒快速喷射送入预氧化区内破除其黏结性, 形成的半焦进入气化区内发生气化反应, 进而实现对黏结性煤的利用。本工作采用小型流化床射流预氧化反应装置研究较强黏结性煤预氧化破黏后的产物分布、半焦结构与活性变化, 并考察气化操作条件(温度、当量空气系数、水煤比等)对半焦气化行为的影响。结果表明:当预氧化区温度为950℃、当量空气系数为0.13时, 黏结性煤生成半焦的孔结构和气化活性较好;当半焦气化区温度为1000℃、当量空气系数为0.17、水蒸气与煤质量比为0.09时, 生成燃气的品质较好, 而且生成焦油中的轻质组分最多, 有利于焦油被进一步脱除。研究结果可为射流预氧化气化技术的设计放大提供基础数据。     

基于Fluent软件的生物质气化模拟研究

基于Fluent软件,建立流化床反应器模型,对生物质-水蒸气气化过程进行模拟,研究温度对生物质气化过程的影响,同时分析碳转化率、气体成分以及气体总产率的变化规律。结果表明:模拟结果与实验数据吻合良好,碳转化率及气体总产率随温度的升高而升高,床层高度对CO、 H₂生成具有较大影响。模拟计算条件下,氢气体积分数高达55%,这说明水蒸气作为气化介质有利于气化过程中产生更多的H₂。Fluent软件能够很好的对生物质气化过程进行模拟,可以作为生物质气化研究的一个重要工具。     

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%。     

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.     

Gasification of coal and PET in fluidized bed reactor

Blended fuel comprising 23 wt.% polyethyleneterephthalate (PET) and 77 wt.% brown coal was gasified in an atmospheric fluidized bed gasifier of laboratory-scale. The gasification agent was composed of 10 vol.% O₂ in bulk of nitrogen. Thermal and texture analyses were carried out to determine the basic properties of the fuel components. The influence of experimental conditions, such as the fluidized bed and freeboard temperatures on major and minor gas components and tar content, as well as features of the blended fuel gasification in comparison with the single coal gasification, were studied. In the case of coal with PET gasification, only the fluidized bed temperature showed significant influence on CO, CO₂, CH₄ and H₂ content in the producer gas, whereas the effect of the freeboard temperature was insignificant. In single coal gasification both temperatures had considerable and almost the same influence. The content of minor components, such as ethane, ethylene, acetylene and benzene, was found to be more dependent on the freeboard temperature than on the fluidized bed temperature. It was observed that the higher the freeboard temperatures get, the lower is the concentration of the minor components, with the exception of acetylene. The absolute contents of almost all minor and tar components were approximately three times higher in blended fuel gasification than that in single coal gasification. Finally, partition of carbon (char) and selected metals into bottom and cyclone ash in gasification of both fuels is discussed.