Second stage porous media burner for syngas enrichment

The syngas production from hydrocarbons by porous media combustion (or conventional gasification) processes has been intensively and extensively studied due its calorific value and its applications in the energy sector. However, the syngas produced in a first stage gasifier can still have concentrations of light hydrocarbons (e.g., methane) which can be post-processing for further enrichment of hydrogen and carbon monoxide. The present work numerically investigates the performance of a second stage porous media burner to enrich the syngas content, mainly hydrogen and carbon monoxide. A one-dimensional model based on a two-temperature approximation is implemented, based on the PREMIX code, and supported by CHEMKIN and GRI-MECH 3.0 database and routines. From hybrid porous bed reactor experiments, five types of mixtures in the equivalence ratio range between 0.4 and 2.4 are tested: pure methane as baseline, pure Eucalyptus nitens syngas, pure Pinus radiata syngas, and two mixtures of methane with each of the biomass syngas in equal volume quantities, as transition points. The results obtained show that in the enriched syngas, in comparison to the first content after the first stage reactor, the concentrations of hydrogen and carbon monoxide increase, due to the partial oxidation of methane, however part of the hydrogen is consumed in the process. The intermediate species present in methane processing for pure syngas mixtures have broader reaction zones and in lower concentrations compared to the use of pure methane. For equivalence ratios greater than 1.9, pure syngas mixtures show higher conversion efficiencies compared to the baseline. At the equivalence ratio of 2.4, the pure syngas from Eucalyptus nitens and Pinus radiata has an energy return over energy invested (EROI) of 58.27% and 53.95%, respectively, and a maximum hydrogen and carbon monoxide yields of 31.66% and 48.40%, respectively. In the case of the Pinus radiata, the outlet syngas concentrations of the hydrogen and carbon monoxide on dry basis expose an increment about two times in comparison to the initial concentrations.     

双金属共改性沸石催化杉木热解制备轻质芳烃

以杉木为原料在金属改性分子筛作用下进行热解制备芳烃,采用热裂解-气相色谱质谱法进行热解。结果表明：单金属改性中5%Zn/HZSM-5可达到最好催化效果,其芳烃的相对峰面积达到最高的34.17%,苯、二甲苯的产率相对最高;与单金属改性相比,1%Zn-4%Co/HZSM-5可增大单环芳烃产率,其中苯增大1.19倍,甲苯增大1.21倍;萘、甲基萘等大分子芳烃产率显著减小,同时氧化物产率减少。验证不同金属结合会产生某种协同效应,在热解过程中添加双金属改性分子筛有利于热解油品位的提高。通过NH₃-TPD表征和BET测试阐述金属改性对催化剂表面结构及酸位点变化的影响。     

水蒸气气氛下生物质与聚丙烯共气化产气特性数值分析

搭建生物质与废塑料共气化动力学模型,并用实验数据对其进行验证。选用6种生物质和聚丙烯作为共气化反应物,以水蒸气为气化剂,计算气化温度在300～1000℃之间、气化压强在0.1～0.8 MPa之间、聚丙烯和松木锯末质量比例在0.5～2.5之间,以及不同生物质类型等对生物质和聚丙烯共气化产气特性的影响。结果表明：松木锯末气化中添加聚丙烯后,最高产气量和最大产气速率增加,最高产气总流量提高21.46%,最高产气速率提高4.64%,H₂和CO最高产量分别提高54.27%和79.51%;压强增加不利于提高共气化产气的H₂和CO含量,有利于提高CH₄含量;6种常见生物质和聚丙烯共气化产氢量大小顺序为：果皮>棉花秆≈玉米秸秆>杨树木屑>稻秆>条浒苔;聚丙烯掺混比率增加有利于提高H₂、CO和CH₄等组分产量。     

木素磺酸盐经催化热分解向轻质芳烃的转化

以轻质芳烃苯、甲苯、二甲苯以及萘（BTXN）为目标产物，使用粉粒流化床对制浆废液中的木素磺酸盐进行了催化热分解实验，研究了常压下催化剂的种类、氛围气体、热分解温度等因素对热分解中间产物BTXN收率的影响。实验结果表明，术素磺酸盐含硫量高，而且挥发物质随温度变化大。在非活性流化介质硅砂下，反应气体的种类对木素磺酸盐热分解产物的影响较小；在氢气气氛下，催化剂CoMo-B可大大促进初次热分解来的焦油二次加氢分解反应，使中间产物苯、甲苯、二甲苯和萘等轻质芳烃化合物的收率有了明显提高，质量分数达2．52％，是介质硅砂条件下的3．3倍。要提高中间产物BTXN的收率，选择抗硫性强、加氢活性高的催化剂十分重要。     

生物质固体成型燃料燃烧监测技术与设备研究

介绍了典型的生物质固体成型燃料自动燃烧器和成型燃料炉排式锅炉,分析了国家相关设备的热工性能检测指标、污染物排放监测指标及国内外成型燃料燃烧设备的监测系统的差距,指出我国目前存在的燃烧设备检测监测标准缺乏、不完善,监测设备独立、单一及未成系统等问题,提出提高燃烧效率,建立统一的评价标准等相关建议,以期为我国生物质固体成型燃料产业发展提供参考。     

发展生物质能源所面临的问题分析

国内外生物质能主要燃料存在差异,国内对燃料系统的研究又不够充分,因此燃料系统的问题仍是限制生物质能发展的最主要问题。以国能惠民生物质项目为例,分析总结了调试期间影响运行的因素。     

腐生真菌Mucor indicus发酵生产酒精性能的初步研究

对腐生真菌Mucor indicus在复杂的含碳培养基中发酵产生酒精的性能进行了研究.结果表明,在好氧和厌氧条件下,菌体生物量与温度成线性关系,随pH的升高而增加.在分别以葡萄糖、木糖、葡萄糖和木糖为不同碳源的发酵中,酒精转化率分别为0.44 g/g、0.18 g/g和0.46 g/g,该菌株显示出了较好的同时代谢六碳糖和五碳糖的能力.     

Experimental investigation of pyrolysis process of woody biomass mixture

This paper describes an experimental investigation of pyrolysis of woody biomass mixture. The mixture consists of oak, beech, fir, cherry, walnut and linden wood chips with equal mass fractions. During the experiment, the sample mass inside the reactor was 10 g with a particle diameter of 5-10 mm. The sample in the reactor was heated in the temperature range of 24-650℃. Average sample heating rates in the reactor were 21, 30 and 54 ℃/min. The sample mass before, during and after pyrolysis was determined using a digital scale. Experimental results of the sample mass change indicate that the highest yield of pyrolytic gas was achieved at the temperature slightly above 650℃ and ranged from 77 to 85%, while char yield ranged from 15 to 23%. Heating rate has sig- nificant influence on the pyrolytic gas and char yields. It was determined that higher pyrolysis temperatures and heating rates induce higher yields of pyrolytic gas, while the char mass reduces. Condensation of pyrolytic gas at the end of the pyrolysis process at 650℃ produced 2.4-2.72 g of liquid phase. The results obtained represent a starting basis for determining material and heat balance of pyrolysis process as well as woody biomass pyrolysis equipment.     

我国生物质能源现代化应用前景展望(一)——生物质资源和供给

生物质能除了可以在改善世界一次能源结构、降低化石能源需求量方面做出重要贡献以外,还可在减少温室气体排放、保障能源供应安全、改善贸易平衡、促进农村发展和改进城市废弃物处理方式等方面发挥作用。目前全球每年一次能源消费总量为500EJ,生物质资源的年用量约占一次能源消费总量的10%左右,主要被用于传统的民用燃料和生产第一代生物燃料。第二代生物燃料技术预计将于2020年前后在一些国家实现工业化生产。IEA预测,2050年世界一次能源需求量为670EJ,生物质资源将占一次能源需求总量的20%左右。各方学者预测的2050年全球生物质资源量最低值基本在200~400EJ之间,最高值在400~1500EJ之间。中国的生物燃料产业尚处于起步阶段,不过应该说取得了良好的开端。我国生物质资源相对较少,且分布不均,发展生物质能产品需要依靠能源作物。只有通过合理开发、有效利用,才能在不与粮食和食用油争夺土地的前提下,在一定程度上提供生物运输燃料和生物质发电供热所需的原料,生物质能-农产品和/或生物质能-林产品联合生产系统应成为主要发展方向。美国生物燃料产业的发展模式对我国具有一定的借鉴意义。生物质最有效的利用方式是生产运输燃料,从长远来看,生物燃料可以与石油燃料竞争,尤其是喷气燃料和汽油更具替代优势,但受到生物质资源供应量的制约。     

秸秆涡旋燃烧颗粒排放特性影响研究

利用颗粒物分级采样及烟气实时监测技术,研究稻草在涡旋燃烧炉燃烧时燃烧温度、一二次风配比、过量空气系数等参数对飞灰颗粒排放特性的影响。实验表明稻草燃烧产生的亚微米颗粒PM1及微细颗粒PM1-2.5主要由KCl和K2SO4组成。提高燃烧温度、增大一二次风配比将增加PM1排放浓度。试验中随着一二次风配比的增大或燃烧过量空气系数的增大,不同粒径颗粒的S/Cl摩尔比将增大,而适当的燃烧过量空气系数有利于减少PM和CO排放。