Hydrogen-rich gas production from biomass air and oxygen/steam gasification in a downdraft gasifier

Biomass gasification is an important method to obtain renewable hydrogen. However, this technology still stagnates in a laboratory scale because of its high-energy consumption. In order to get maximum hydrogen yield and decrease energy consumption, this study applies a self-heated downdraft gasifier as the reactor and uses char as the catalyst to study the characteristics of hydrogen production from biomass gasification. Air and oxygen/steam are utilized as the gasifying agents. The experimental results indicate that compared to biomass air gasification, biomass oxygen/steam gasification improves hydrogen yield depending on the volume of downdraft gasifier, and also nearly doubles the heating value of fuel gas. The maximum lower heating value of fuel gas reaches 11.11 MJ/N m³ for biomass oxygen/steam gasification. Over the ranges of operating conditions examined, the maximum hydrogen yield reaches 45.16 g H₂/kg biomass. For biomass oxygen/steam gasification, the content of H₂ and CO reaches 63.27–72.56%, while the content of H₂ and CO gets to 52.19–63.31% for biomass air gasification. The ratio of H₂/CO for biomass oxygen/steam gasification reaches 0.70–0.90, which is lower than that of biomass air gasification, 1.06–1.27. The experimental and comparison results prove that biomass oxygen/steam gasification in a downdraft gasifier is an effective, relatively low energy consumption technology for hydrogen-rich gas production.     

生物质半焦气化的反应动力学

利用热重分析仪研究了CO2气氛下的生物质半焦的反应性。研究发现，所研究的4种生物质半焦都表现出了相同的反应性趋势。其反应性随着转化率的增加而增加。这可能是由于生物质焦样中的碱金属含量，尤其是钾的含量较高的原因。对比生物质气化反应动力学参数研究表明，4种焦样的气化行为可以用收缩核模型来描述，并求出了4种生物质焦样的反应动力学参数。在不同的CO2分压下进行了花生壳焦样的反应性实验研究，发现焦样的反应性正比于反应气体浓度，求出了花生壳焦样的反应动力学方程式。     

钢筋焊接网设计与应用的新进展

钢筋焊接网在国内还未形成规模,与国外发展相差甚远。通过对国内外在设计计算理论、试验研究和实际运用方面的研究,总结了当前最实用的计算方法和在不同混凝土构件中的应用所表现的特性,为大力推广应用钢筋焊接网提供计算理论依据,并为进一步规范施工操作奠定基础。     

基于对羟基苯丙酸的生物基液晶共聚酯纤维的合成与性能

针对常规生物基纤维力学性能与耐热性不足的问题,以6-羟基-2-萘甲酸、对羟基苯甲酸和对羟基苯丙酸(HPPA)为原料,采用一锅熔融聚合法合成了生物基液晶共聚酯,并通过熔融纺丝制备得到初生纤维,对共聚酯及其初生纤维的结构与性能进行研究.结果表明:制备得到的生物基液晶共聚酯为向列型液晶,其熔点在200℃左右,并随着HPPA添...     

同色异谱现象的产生与控制

随着客户对纺织品物理指标要求的提高,染色生产过程中对同色异谱现象的控制就成了一个很重要的环节.本文对同色异谱现象的产生进行了分析和判定,制定了合理的解决方案以避免和减轻同色异谱的程度.     

混凝剂复配处理山梨酸废水的实验研究

选用氢氧化钙复配聚丙烯酰胺对山梨酸废水进行了预处理,考察了混凝剂用量、温度、搅拌时间等因素对CODcr去除率的影响。结果表明：在氢氧化钙用量为16g／L、聚丙烯酰胺用量为5mg／L、混凝温度50℃、搅拌时间3min时,CODcr去除率可达43．1％。氢氧化钙复配聚丙烯酰胺的混凝效果明显优于氢氧化钙和聚丙烯酰胺单独使用时的效果,并且可显著缩短絮体沉降时间。     

Design and operation of integrated pilot-scale dimethyl ether synthesis system via pyrolysis/gasification of corncob

The integrated pilot-scale dimethyl ether (DME) synthesis system from corncob was demonstrated for modernizing utilization of biomass residues. The raw bio-syngas was obtained by the pyrolyzer/gasifier at the yield rate of 40-45 Nm³/h. The content of tar in the raw bio-syngas was decreased to less than 20 mg/Nm³ by high temperature gasification of the pyrolysates under O₂-rich air. More than 70% CO₂ in the raw bio-syngas was removed by pressure-swing adsorption unit (PSA). The bio-syngas (H₂/CO ≈ 1) was catalytically converted to DME in the fixed-bed tubular reactor directly over Cu/Zn/Al/HZSM-5 catalysts. CO conversion and space-time yield of DME were in the range of 82.0-73.6% and 124.3-203.8 kg/m_cat³/h, respectively, with a similar DME selectivity when gas hourly space velocity (GHSV, volumetric flow rate of syngas at STP divided by the volume of catalyst) increased from 650 h⁻¹ to 1500 h⁻¹ at 260 °C and 4.3 MPa. And the selectivity to methanol and products was less than 0.65% under typical synthesis condition. The thermal energy conversion efficiency was ca. 32.0% and about 16.4% carbon in dried corncob was essentially converted to DME with the production cost of ca. ¥ 3737/ton DME. Cu (1 1 1) was assumed to be the active phase for DME synthesis, confirmed by X-ray diffraction (XRD) characterization.     

放射性废物处置中核素迁移研究现状及展望

放射性废物根据分类标准采取不同的处置方式。放射性核素具有半衰期长、放射性强等特点,调研了国内、外低、中、高放射性核素处置研究的工作进展,并从核素种类、黏土类型、具体迁移研究方法、研究设备方面,总结了当前国内、外的研究现状,对我国放射性废物处置中的核素迁移工作提出了相应的建议。     

射孔水平井产能预测方法

为了预测射孔水平井的产能,在Joshi推导水平井产能公式所用模型的基础上,引入了三径向流模型,采用等值渗流阻力法,建立了孔眼未射穿污染带和孔眼射穿污染带2种情况下射孔水平井产能预测模型,考虑了孔深、孔密、孔径、相位、污染带的半径与污染程度、压实带的厚度与压实损害程度、水平井水平段长度等因素对产能的影响,流动机理更加符合油藏实际。利用所建立的产能预测模型进行参数敏感性分析,结果表明,射孔水平井产能随着孔深、孔径、孔密、相位、水平井水平段长度等参数的增大而增大,随着压实带厚度和压实损害程度的增大而减小,对水平井水平段长度、孔深、孔密、压实损害程度的敏感性较大,对相位、孔径、压实带厚度的敏感性较小;孔眼射穿污染带时产能指数对射孔参数的敏感性比孔眼未射穿污染带时低。工程设计时,应尽量增加水平井水平段长度、孔深、孔密,避免过高的压实损害程度。     

裕隆换流站换流阀阀基电子设备投旁通对故障的研究

针对投旁通对结束时因脉冲频率转换产生延时而出现误触发的问题,提出一种基于最短作业优先算法[1]的控制策略,核心思想是投旁通对结束后不直接检测信号的频率是10 kHz 还是1 MHz,而是先在程序上认为投旁通对命令(bypass pair order,BPPO)有0、1两种状态,BPPO 信号为1 MHz 时置为1,其他时候均置为0.如果检测到 BPPO 的状态不为1,则认为投旁通对结束.此过程只需延时几μs,由于延时时间较短,在此期间识别不出控制脉冲,可以有效地避免误触发的发生.基于这种改进控制策略设计的阀基电子设备已经在实时数字仿真器联调试验中得到应用.试验结果表明该控制策略能有效消除原保护方法因误触发而产生的短路电流,减小了系统误动作的机率