加压射流流化床煤催化气化制天然气的模拟研究

以煤催化气化制合成天然气技术为研究背景,内径0.2 m,高6 m,处理量为0.5 t/d的流化床气化炉为研究对象,建立了煤催化气化流化床气化炉的数学模型。将气化炉简化为3个区域:分布板区、气泡区和自由段区,基于稳态一维模型,考虑了加压下流体力学性质(最小流化速度、射流高度和直径、气泡直径和速度以及床层膨胀比),质量和热量传递,以及催化气化反应动力学(煤焦燃烧、水蒸气气化、变换和甲烷化)等因素对气化结果的影响。计算结果表明:当射流管引入氧气后,颗粒温度迅速达到最大值随后下降最后趋于平缓;氢气和二氧化碳浓度随着床高近似线性增加,但一氧化碳和甲烷随床高增加缓慢;3.1 MPa时最大气泡直径约为0.11 m,气化炉内不会发生节涌现象。计算床温和气体组成与实验结果有良好的一致性。     

不同配气工艺下生物质固定床气化试验研究

采用自主研发的连续运行主动配气下吸式固定床气化炉为试验平台,研究了不同配气工艺下气化炉内温度场和压力场的变化,并且以稻草为气化原料进行气化试验,分析了不同配气工艺对燃气组分、燃气热值和燃气中焦油质量浓度的影响。结果表明:改变配气工艺从单层配气到双层配气再到三层配气,反应炉内温度逐渐升高,反应炉内各层压力逐渐均匀,三层配气时炉内氧化层温度在1 100℃左右,炉内最高压力为24.1 kPa,三层配气时气化炉内温度场和压力场的分布具有较高气化反应特性;同单层配气和双层配气相比,三层配气工艺下以稻草为气化原料燃气组分中H2和CO的体积分数明显提高,其值分别为10.23%和20.49%,相比于单层配气提高了3.08%和2.28%,单层配气、双层配气和三层配气工艺下燃气热值分别为4 656.82 kJ/m3、4 934.99 kJ/m3和5 476.77 kJ/m3,燃气中焦油质量浓度分别为0.834×10-3kg/m3、0806×10-3kg/m3和0.721×10-3kg/m3。     

流化床作为生物质气化反应器试验研究

在流化床生物质气化炉内 ,用空气进行气化生物质 (花生壳 )的试验研究 ,分析的参数是当量比ER 0 .2— 0 .4 5 ,气化床的温度 75 0— 85 0℃和加入二次风。当ER在 0 .2 5— 0 .33,气化燃气热值为 6 .2— 6 .8MJ/m3 ,气体产量在 2 6 0— 390m3 /h ,生物质燃烧时比气化产量在 1.2 8— 2 .0 3m3 /kg之间 ,炭转化率在 5 3%— 80 %。并对 7种农、林废弃物进行了初步气化试验研究 ,生成的燃气体积分数 :CO为 14 %— 18% ,H2 一般低于 6 % ,甲烷 4 %— 12 %。燃气热值在 4 70 0— 710 0kJ/m3 。试验结果表明 ,在流化床生物质气化炉中 ,通过在悬浮空间加入二次风 ,可使燃气热值得到提高。     

煤颗粒对化学热回收二段式煤气化工艺的影响

基于碳和水蒸气、CO2气化的吸热化学反应原理,开发出回收煤气显热的高效化学热回收二段式煤气化工艺,可有效提高现有气流床气化技术的热效率.文中在实验室规模的热态反应平台上,对二段气化床层内煤颗粒粒径对二段床层内的温度分布、二段气化效率及煤渣层残炭率的分布规律进行了实验.研究优选出二段气化炉内煤颗粒粒径范围为10-15 m...     

鲁奇炉加压气化工艺影响因素分析

鲁奇加压气化工艺是以长焰煤为原料,水煤汽和工业氧气为气化剂生产粗煤气。在气化炉中,根据原料的反应情况可分为灰渣层、氧化层、还原层、干馏层和干燥层5个层。氧化层和还原层统称为气化区,是气化反应的主体。根据反应进程,还原层又分为第一还原层和第二还原层。在气化炉中,沿床层高度煤和煤气的温度是变化的。气化炉工况较好时,氧单位负荷高,煤气出口温度和灰区温度较低,且波动较小。炉温中间高,两头低,汽氧比小。灰渣中碳量少,灰渣粒度大而均匀。生产工艺的影响因素有以下几个方面。     

固体热载体外循环逆流移动床生物质气化工艺

基于实验室外循环逆流移动床(ECCMB)催化气化反应体系进行了生物质气化实验研究。该反应系统由移动床热解反应器、气固逆流移动床气化反应器和提升管燃烧反应器组成。以白松木屑为生物质原料、煅烧橄榄石为热载体(催化剂)进行气化实验,考察了热解器温度、水蒸气质量/生物质质量(S/B)、原料粒度以及气化器床层高度对气化结果的影响。实验结果表明:反应器温度和S/B是影响气化产品分布的重要因素;随热解温度的升高,气体产率和化学效率显著提高,氢气含量也有所增加;水蒸气的加入不仅提高了产气率,焦油含量明显降低;原料颗粒粒度和气化器床层高度均对产品分布和化学效率产生不同程度的影响。     

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%。     

输运床粉煤气化中试装置断煤现象原因分析及预防措施

输运床粉煤气化中试装置给煤系统采用流化进料器,干法粉煤进料,粉煤被高压气体输送至气化炉,在第2次试验过程中发现给煤系统出现断煤现象。通过对断煤现象的运行数据分析,得出:粉煤粒径过细和粉煤给料仓松动气带水均可能会影响正常给煤;粉煤流量在1. 6t/h运行工况下,输煤气速低于6. 09 m/s(显示值低于4. 3 m/s)会导致给煤系统出现断煤,从而直接影响对整个气化炉反应区的控制,影响系统的稳定、安全运行。     

煤气化技术工业应用概况及工艺选择(下)

正1.3气流床气化工艺气流床气化工艺有干法进料和湿法进料2种形式,将煤粉(粒度100μm)或煤浆与气化剂一起由喷嘴高速喷入气化炉,气化炉内气流速率超过颗粒夹带气速,气固并流运动并发生高温燃烧和气化反应(约1 500℃),煤灰呈熔融状排出气化炉。气流床气化的高温、高压、强混合过程有利于提高气化强度,具有生产能力大、碳转化率高、煤气     

粉煤气化系统的检测与控制

我公司粉煤气化装置采用的是灰熔聚循环流化床粉煤多元气化工艺。它是利用流态化原理，将原料粉煤连续加入气化炉密相区，气化剂（纯氧、蒸汽）从气化炉底部吹入，使煤粒沸腾流化，在燃烧产生的高温条件下，气固两相充分混合接触，发生煤的热解、破粘和碳的氧化还原反应，最终实现煤的气化。该气化装置由给煤、气化、除尘、废热回收、粗煤气洗涤冷却、灰和渣收集排出等单元组成。本文主要就气化炉系统工艺控制参数的的检测与控制展开讨论。     

A novel biomass air gasification process for producing tar-free higher heating value fuel gas

Biomass is a promising sustainable energy source. A tar-free fuel gas can be obtained in a properly designed biomass gasification process. In the current study, a tar-free biomass gasification process by air was proposed. This concept was demonstrated on a lab-scale fluidized bed using sawdust under autothermic conditions. This lab-scale model gasifier combined two individual regions of pyrolysis, gasification, and combustion of biomass in one reactor, in which the primary air stream and the biomass feedstock were introduced into the gasifier from the bottom and the top of the gasifier respectively to prevent the biomass pyrolysis product from burning out. The biomass was initially pyrolyzed and the produced char was partially gasified in the upper reduction region of the reactor, and further, char residue was combusted at the bottom region of the reactor in an oxidization atmosphere. An assisting fuel gas and second air were injected into the upper region of the reactor to maintain elevated temperature. The tar in the flue gas entered the upper region of the reactor and was decomposed under the elevated temperature and certain residence time. This study indicated that under the optimum operating conditions, a fuel gas could be produced with a production rate of about 3.0 Nm³/kg biomass and heating value of about 5000 kJ/Nm³. The concentration of hydrogen, carbon monoxide and methane in the fuel gas produced were 9.27%, 9.25% and 4.21%, respectively. The tar formation could be efficiently controlled below 10 mg/Nm³. The system carbon conversion and cold gasification efficiency reached above 87.1% and 56.9%, respectively. In addition, the investigation of energy balance for the scale-up of the proposed biomass gasification process showed that the heat loss could be recovered by approximately 23% of total energy input. Thus, partial fuel gas that was produced could be re-circulated and used to meet need of energy input to maintain the elevated temperature at the upper region of reactor for tar decomposition. It was predicted the heating value of product fuel gas would be 8000 kJ/Nm³ if the system was scaled up.     

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％。     

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。     

下吸式气化炉中生物质气化发电的运行与测试

对25kW下吸式生物质气化发电机组进行了运行测试。结果表明：下吸式生物质气化发电机组运行稳定，操作方便；所产生的燃气中焦油较低，可达1．9g／Nm^3；燃气中的气体成分为：H2，13％～14％；CO，19％～24％；CH4，1％～3％；CO2，11％～16％；N2，49％～50％。气体的高位热值为4326kJ／Nm^3～6005kJ／Nm^3；产气比为1．65Nm^3／kg～2．28Nm^3／kg Fuel；气化过程中碳的转化率为32．34％～43．36％；气化效率为41．19／5～78．85％，系统总效率为11．5％～22．8％。     

Gasification and co-gasification of biomass wastes: Effect of the biomass origin and the gasifier operating conditions

Air gasification of different biomass fuels, including forestry (pinus pinaster pruning) and agricultural (grapevine and olive tree pruning) wastes as well as industry wastes (sawdust and marc of grape), has been carried out in a circulating flow gasifier in order to evaluate the potential of using these types of biomass in the same equipment, thus providing higher operation flexibility and minimizing the effect of seasonal fuel supply variations. The potential of using biomass as an additional supporting fuel in coal fuelled power plants has also been evaluated through tests involving mixtures of biomass and coal–coke, the coke being a typical waste of oil companies. The effect of the main gasifier operating conditions, such as the relative biomass/air ratio and the reaction temperature, has been analysed to establish the conditions allowing higher gasification efficiency, carbon conversion and/or fuel constituents (CO, H₂ and CH₄) concentration and production. Results of the work encourage the combined use of the different biomass fuels without significant modifications in the installation, although agricultural wastes (grapevine and olive pruning) could to lead to more efficient gasification processes. These latter wastes appear as interesting fuels to generate a producer gas to be used in internal combustion engines or gas turbines (high gasification efficiency and gas yield), while sawdust could be a very adequate fuel to produce a H₂-rich gas (with interest for fuel cells) due to its highest reactivity. The influence of the reaction temperature on the gasification characteristics was not as significant as that of the biomass/air ratio, although the H₂ concentration increased with increasing temperature.     

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.     

生物质下吸式气化炉气化制备富氢燃气实验研究

以制取富氢燃气为目标,在自热式下吸式气化炉反应器内,进行了生物质下吸式气化炉富氧/水蒸气及空气气化的制氢特性研究。实验结果表明,与空气气化相比,富氧/水蒸气气化可显著提高氢产率和产气热值。在实验条件范围内,最大氢产率达到45.16 g/kg;最大低位热值达到11.11 MJ/m3。在富氧/水蒸气气化条件下,燃气中H2+CO体积分数达到63.27%—72.56%,高于空气气化条件下的52.19%—63.31%。富氧/水蒸气气化条件下的H2/CO体积比比值为0.70—0.90,低于空气气化条件下的1.06—1.27。实验结果证实:生物质下吸式气化炉富氧/水蒸气气化是一种有效的制取可再生氢源的工艺路线。     

A comparison of the energy and product distribution from biomass gasifiers

A detailed analyses of the raw producer gas streams generated by a downdraft gasifier and by a fluidized-bed gasifier are presented and are discussed in terms of raw gas clean-up considerations and of energy conversion efficiency. The major gasifier operating parameters such as fuel/air ratio, carbon conversion efficiency, net energy conversion efficiency, and producer gas heating value are then compared between seven operational gasifiers and a computer simulation model of a fluidized-bed gasifier developed by Queen's University. It is concluded that the Queen's University model correctly predicts that the fuel/air ratio is the single most important parameter for determining gasifier performance. Downdraft gasifiers exhibit superior energy conversion efficiency and producer gas quality because they utilize a higher fuel/air ratio than do fluidized bed gasifiers.     

煤粉粒径对HNCERI气化炉碳转化率与固/液渣层分布的影响

以中国华能集团清洁能源技术研究院（Huaneng Clean Energy Research Institute,HNCERI）两段干粉加压气化炉为研究对象,采用考虑了焦炭颗粒表面气体组分扩散效应的随机孔模型计算焦炭气化反应速率以评估碳转化率。同时,耦合熔渣子模型计算气化炉一段壁面固液渣层分布特性和热损失,研究了煤粉粒径对HNCERI气化炉碳转化率和固液渣层分布特性的影响。结果表明所构建的模型可以准确预测气化炉出口主要气体组分组成、碳转化率和气化炉一段壁面热损失;气化炉一段碳转化率受固有气化速率和停留时间控制,二段主要受颗粒停留时间控制;因此,通过减小煤粉粒径可以减小气体在颗粒表面扩散阻力,有利于提高气化炉一段碳转化率,而适量增加煤粉粒径可以增加煤粉颗粒在气化炉二段的停留时间,有利于提高二段碳转化率。模拟结果显示煤粉颗粒粒径从20μm增加到200μm,一段碳转化率从99.68%降低到了95.06%,二段碳转化率从69.03%增加到了89%。煤粉粒径对气化炉上缩口和直段壁面液态渣层分布影响很小,但显著影响固态渣层厚度的发展。