核电厂大修期间蒸汽发生器U型管返水引发的安全风险及对策

核电厂大修期间,反应堆排水到压力容器法兰面水位后,蒸汽发生器U型管中吸附的水会大量返回到一回路,造成一回路水位控制困难并引发一系列安全风险,对大修人员、设备和反应堆堆芯安全都构成威胁.结合秦山第二核电厂换料大修中蒸汽发生器U型管返水的数据,对蒸汽发生器U型管返水的机理以及带来的安全风险进行了分析,并结合大修工作安排提出...     

燃气-蒸汽联合循环供热项目主机选型方案刍议

发展燃气-蒸汽联合循环供热对于解决经济发展和环境保护具有重要作用，在我国经济发达地区已经开始大规模推广。阐述了燃气一蒸汽联合循环发电、供热技术、特点等，对主机选型方案提出建议。     

Biogas from the organic fraction of municipal solid waste: Dealing with contaminants for a solid oxide fuel cell energy generator

The present work investigates electricity production using a high efficiency electrochemical generator that employs as fuel a biogas from the dry anaerobic digestion of the organic fraction of municipal solid waste (OFMSW).The as-produced biogas contains several contaminants (sulfur, halogen, organic silicon and aromatic compounds) that can be harmful for the fuel cell: these were monitored via an innovative mass spectrometry technique that enables for in-line and real-time quantification.A cleaning trap with activated carbons for the removal of sulfur and other VOCs contained in the biogas was also tested and monitored by observing the different breakthrough times of studied contaminants.The electrochemical generator was a commercial Ni anode-supported planar Solid Oxide Fuel Cell (SOFC), tested for more than 300 h with a simulated biogas mixture (CH₄ 60 vol.%, CO₂ 40 vol.%), directly fed to the anode electrode. Air was added to promote the direct internal conversion of CH₄ to H₂ and CO via partial oxidation (POx).The initial breakthrough of H₂S from the cleaning section was also simulated and tested by adding ～1 ppm(v) of sulfur in the anode feed; a full recovery of the fuel cell performance after 24 h of sulfur exposure (～1 ppm(v)) was observed upon its removal, indicating the reliable time of anode exposure to sulfur in case of exhausted guard bed.     

Effects of different pretreatment methods on the enzymatic hydrolysis of oak shell

Sawtooth Oak (Quercus acutissima) shells were used as a renewable and low-cost agricultural residue for bioethanol production for the first time. The efficiency of H₂SO₄, NaOH, steam explosion and the combination of these methods was compared in terms of delignification, saccharification efficiency and yield. The structural features of samples were characterized by SEM, XRD and FTIR. Results show H₂SO₄/steam explosion resulted in the highest hemicellulose reduction (98.5%) and cellulose recovery yield (99.9%). NaOH /steam explosion resulted in the highest delignification level (31.5%). Steam explosion exhibited the highest enzymatic digestibility of 98.8% and total product yield of glucose of 84.8%, an increase of 130.8% and 98.1% than that of untreated oak shell, respectively, which seemed to be the most effective for improving enzymatic saccharification. The results of structural features showed the structure and surface of shells were changed that is in favor of the following enzymatic hydrolysis.     

载体结构对Co/MgO-Al2O3催化剂催化C2H6/CO2反应性能的影响

采用共沉淀-浸渍法制备了不同载体结构的Co/Al₂O₃、Co/MgO_（25）-Al₂O_3（75） （Co/M₁A₃-Spinel）、Co/MgO_（75）-Al₂O_3（25） （Co/M₃A₁-Solid）和Co/MgO催化剂,用于CO₂氧化乙烷脱氢（ODEC）和乙烷干重整（DRE）反应.XRD、Raman、H₂-TPR、XPS表征结果表明,载体结构显著影响催化剂上Co物种的落位、结构和还原性能.Co³⁺和Co²⁺在C₂H₆/CO₂反应气氛中可相互转化,促进C₂H₆和CO₂活化;尖晶石结构中的Co物种比固溶体中的Co物种可还原性强,在高温ODEC反应条件下,催化剂表面的Co物种会被还原成Co⁰,协同Co³⁺/Co²⁺导致C—C键和/或CC键断裂,使得反应路径向DRE转变.MgO基固溶体结构中Co物种与载体相互作用更强,在高温ODEC反应中避免了被大量还原为低价态的Co⁰,ODEC反应可稳定进行.     

过热蒸汽干燥乏汽余热利用技术

干燥是一个高能耗的操作过程,降低能耗是提高整个干燥系统能量利用效率的关键。文中阐述了过热蒸汽特性及干燥节能的本质与途径,指出过热蒸汽干燥成功实现节能的关键是如何经济地利用干燥过程产生的多余乏汽。并对传统热回收、多级干燥、机械蒸汽再压缩、自回热四种乏汽利用技术进行了分析比较,指出了各项技术的优缺点,最后对过热蒸汽干燥过程节能进行了总结。基于火用回收的自回热过热蒸汽干燥具有广阔的前景。     

Combined steam-dry reforming of toluene in syngas over CaNiRu/Al2O3 catalysts

Cracking, steam reforming, dry reforming, and combined steam and dry reforming of toluene in model syngas were performed using catalysts to simulate tar removal produced during biomass gasification. The catalysts were prepared by adding Ru, Ca, and Mn to Ni-based catalysts, and their properties were measured using BET, pulse CO chemisorption, XRD and TG. In steam and dry reforming of toluene, a high toluene conversion was observed with increasing Ca content in the catalyst and catalysts containing Ca showed a higher activity than those containing Mn. In combined steam-dry reforming with syngas, 1%CaNiRu/Al₂O₃ indicated a conversion of 93.9% at 800°C.     

Gasification of waste plastics by steam reforming in a fluidized bed

The process of producing synthetic gas from waste plastics by steam reforming was investigated. To evaluate this process, the steam reforming of the oils derived from low-density polyethylene and polystyrene were carried out using a laboratory-scale fluidized bed of Ni-Al₂O₃ catalysts. The performance of gasification in terms of carbon conversion, gas yield, and gas compositions was examined. Although oils derived from plastics contain many kinds of heavy hydrocarbons and aromatics, they were well gasified at temperatures above 1023 K with a steam/carbon ratio of 3.5 and a weight hourly space velocity of 1 h⁻¹. The hydrogen content of the product gas was very high at approximately 72 vol% for polyethylene-derived oil and 68 vol% for polystyrene-derived oil. These compositions agreed well with the values calculated from chemical equilibrium.     

Steam Reforming of Bio-Oil Aqueous Fractions for Syngas Production and Energy

Abstract The biorefinery concept has been proposed as a route map to convert biomass into fuels and chemicals, maximizing economic and environmental benefits while minimizing pollution. A biorefinery strategy based on fast pyrolysis is proposed following a two-stage process, where biomass is first subjected to fast pyrolysis, optimized to collect up to 75% (per unit weight of biomass) of a liquid fraction called bio-oil. This bio-oil or its fractions can be upgraded in a second step to different chemicals, to a syngas and/or to energy. In particular, the catalytic steam reforming of the aqueous fraction of bio-oil obtained by fractionation with water is one of the most attractive possibilities for bio-oil upgrading, yielding a H2-rich syngas with low CO content. From the results obtained, it can be concluded that the best alternative for the catalytic steam reforming process is hydrogen production through further purification of the gas obtained.     

燃煤锅炉水蒸气促燃的理论研究

针对小型火力热电厂中小吨位燃煤锅炉应用现状 ,结合固体燃煤燃烧的机理 ,在详细分析常见锅炉工作原理和燃烧反应特性的基础上 ,提出了用水蒸气促燃降污节能的理论 ,水蒸气介入后促燃化学模型和物理模型的建立 ,证明了这一理论的可行性