三种能源草厌氧发酵制备生物燃气初步研究

以华南地区生长的多年生草本植物象草、芒草和五节芒为原料,采用序批式中温（35 ± 1℃）厌氧发酵工艺,研究这三种能源草制备生物燃气的性能。结果表明：象草、芒草和五节芒的最高日产气率分别为31.33、24.84和19.51 Nml•(gVSadded)−1•d−1,原料产气率分别为355.78、285.58和235.38 Nml•(gVSadded)−1,产甲烷率分别为166.43、109.89和97.20 Nml•(gVSadded)−1,占理论产甲烷率的33.83%、21.67%和19.48%,象草的厌氧发酵性能优于芒草和五节芒的主要原因是象草中纤维素、半纤维素等易降解的有机物含量较高。修正的Gompertz方程拟合效果较好,象草、芒草和五节芒的累积产气量分别为344.81、290.11和279.01 Nml•(gVSadded)−1,延滞期分别为5.96、0.71和0 d。     

里下河区浅水湖泊表层沉积物营养盐溯源分析

以里下河区的大纵湖、得胜湖、蜈蚣湖、九龙口为例,分析了表层沉积物总有机碳（TOC）、总氮（TN）、总磷（TP）的垂向分布特征,探讨了引起其含量变化的影响因子以及三种元素之间的相关性特征,通过C/N和N/P的比值追溯C、N、P的来源。结果表明,四个湖泊中表层沉积物中的TOC含量随深度的增加而降低;刚经过疏浚的湖泊表层底泥中的总有机碳、总氮、总磷含量明显小于其他湖泊;不同湖泊营养盐的相关性存在较大差异;除DS采样点外,研究区域C/N值多介于2~8之间,有机质来源以水生植物为主。     

猪体水热液化工艺参数优化及生物油特性分析

以猪体为原料,以高位热值、C元素回收率、N元素残留率作为生物油质量指标,采用响应面法研究反应温度（220~300 ℃）、反应时间（40~80 min）、固含量（10%~30%）对猪体水热转化生物油产率与质量的影响。研究结果表明：反应条件均会影响水热反应的进行且温度影响最显著,分别在不同反应条件下得到单一指标最优的生物油;生物油的最大产率为76.94%（278 ℃、64 min、29%固含量）,最大HHV值为38.63 MJ/kg（290 ℃、47 min、30%固含量）,最大C元素回收率为93.16%（260 ℃、60 min、10%固含量）,最低N元素残留率为15.52%（220 ℃、40 min、12%固含量）。生物油的元素分析结果表明水热液化可有效降低生物油中N、O元素含量,提高生物油品质。傅里叶变换红外光谱分析与热重分析结果表明,生物油的化学成分复杂且以分子量较大、碳链较长的有机物为主。     

半焦与垃圾衍生燃料混烧的排放特性

在非均匀布风流化床中进行了半焦与垃圾衍生燃料（RDF）的混合燃烧实验,研究了不同半焦混烧率对烟气组分的影响以及二者混烧的可行性与经济性．实验结果表明,随着半焦混烧率的增加,H2O（气态）、CO、HCl、NO及C3H6含量均呈下降趋势,而CO2、SO2含量则呈增加趋势．同时发现,在燃烧过程中增加C1元素含量,可以促进NO的生成．     

餐厨垃圾和牛粪联合厌氧消化动力学探讨

将纯餐厨垃圾、纯牛粪、餐厨垃圾和牛粪以1∶1比例混合为原料,进行联合厌氧消化产气潜能实验,研究和比较3组原料的单位累计产气量、累计产气量、产气速率、pH,CH4含量等参数的变化,通过对产气量进行拟合和以及一级水解动力学分析,发现单组分的系统比较适合一级水解模型。在多组分的系统中,在消化的开始阶段,当易水解的组分如蛋白质、脂质浓度较高时,水解产气比较符合一级水解模型;在消化的中后半部分,当易水解的组分浓度变低,难水解的组分如纤维素等浓度升高时,水解产气与一级水解模型有些偏差,考虑水解组分差别采用Contois模型更合适。     

生物质粉体水蒸气催化气化实验研究

用水蒸气进行梧桐叶粉体的催化气化实验研究。考察了一些主要参数变量，温度（700～900℃）、生物质粉体粒径（〈1mm）、水蒸气／生物质比（0～2．67）、水蒸气压力（0．02MPa-0．08MPa）等对气化结果的影响。实验结果表明：较高的温度有利手氢的产出，但温度过高会使气体热值下降；生物质粉体粒径的大小对产气组分的分布和产气率均有影响；水蒸气的加入使生物质气化产氢率和产气率显著提高，但水蒸气加入量过多使温度下降，产氢率、产气率和产气热值降低。     

稻壳在固定床中空气气化的数值模拟

利用Aspen Plus建立稻壳在上吸式固定床气化炉内的空气气化模型,该模型预测气化温度、产气组分和热值,与试验数据吻合良好。利用Aspen Plus的灵敏度分析模块研究空气当量比ER值对气化温度、气体组分、产气热值以及气化效率的影响。结果表明:随着ER值的增加,气化温度逐渐升高,CO、H2和N2含量逐渐增加,而CH4和CO2含量逐渐减少,热值和气化效率也随之降低。     

基于机器学习的生物质三组分含量预测

为解决生物质中纤维素、半纤维素和木质素测定时耗时耗力等问题,提出基于支持向量回归机(support vector regression machine,SVR)和热重分析法的生物质三组分含量预测模型。通过对4种不同类型核函数的SVR进行比较,利用K折交叉验证法结合网格搜索法,对SVR的参数进行寻优,以获得最优参数进而训练三组分含量的预测模型,并对该模型进行测试和验证。结果表明:该模型具有较好的预测效果,三组分含量预测模型的相关系数R2均在0.9532以上;经验证该模型对毛竹、玉米杆和稻草的三组分含量预测绝对误差控制在2.72%以内。     

球囊导管建立兔急性可控性气管狭窄模型研究

【摘要】 目的 应用球囊导管建立实验兔急性可控性气管狭窄模型,研究气管狭窄程度与血氧饱和度及呼吸频率间关系。方法 将34只新西兰大白兔随机分为对照组（n=4）和实验组（n=30,设A、B、C、D、E 5个亚组,nA~E=6）。对照组兔全身麻醉后行气管切开及气管插管,DSA三维重建测量气管插管下方气管横径和纵径,并记录麻醉前、麻醉-气管切开后及切开后30 min血氧饱和度及呼吸频率;实验组兔气管切开后在气管插管下方管腔置入球囊或球囊＋单弯导管:A组球囊直径3 mm,B组球囊直径3.5 mm,C组球囊直径4.0 mm,D组球囊直径4 mm（＋4 F单弯导管）,E组2个球囊直径分别为4 mm和2 mm,球囊置入前后分别行DSA三维气管重建,测量气管切开处下方气管横径和纵径及扩充球囊最大半径,计算气管狭窄率并记录麻醉前、麻醉-气管切开后及球囊扩充后最终血氧饱和度及呼吸频率。结果 对照组和实验组间及实验组各亚组间兔体重、气管横截面积差异无统计学意义（P＞0.05）;3%戊巴比妥钠（1 ml/kg）全身麻醉对兔血氧饱和度及呼吸频率无明显影响（P＞0.05）;2.8～3.5 kg兔体重与气管横截面积间无明显线性相关性（r=0.41,P=0.23）;实验组A、B、C、D、E组气管狭窄率分别为（39.87±1.43）%、（52.16±2.46）%、（68.77±2.48）、（76.82±2.75）%、（86.49±2.42）%,各组间差异均有统计学意义（P＜0.05）,E组狭窄率最大;A、B组气管狭窄率与狭窄后最终血氧饱和度及呼吸频率无明显相关性（r=0.054,P=0.86;r=0.11,P=0.72）,C、D、E组中气管狭窄率与狭窄后最终血氧饱和度呈显著负相关性（r=-0.85,P＜0.01）,与狭窄后呼吸频率呈显著正相关（r=0.92,P＜0.01）。结论 气管狭窄达到一定程度时,随狭窄程度增加,呼吸功能障碍加重。采用扩张球囊制作兔气管狭窄模型是一种快速、可控性强、操作简单、稳定、重复性好的方法,可为气管狭窄基础研究和临床治疗提供有效可靠的实验载体。     

一株纤维素降解菌的筛选及其在沼气应用中的研究

利用实验室保存的细菌、真菌和从牛粪、猪粪中分离出来的多株菌株,对秸秆纤维素进行降解试验,从而筛选出了能够降解秸秆纤维素(降解率为43.75%)的优势菌株.用几株降解效果较理想的菌株处理秸秆,对处理后的秸秆进行沼气发酵,通过高效气相色谱仪对沼气成分进行分析,发现从牛粪中筛选出的N2菌株效果较好,发酵2周后,其产气中甲烷含量为62.48%(体积分数,下同),二氧化碳含量为31.83%,氮气含量为2.11%.通过生理生化鉴定,初步鉴定N2菌株为枯草杆菌(Bacillus subtilis).     

Effects of biochemical composition on hydrogen production by biomass gasification

Gasification of cellulose, hemicellulose, lignin and three types of real biomass was conducted using an updraft fixed-bed reactor to investigate the effects of temperature (in the range of 920–1220 °C) on the yield and chemical composition of the produced syngas. The experimental results showed that the gasification products of cellulose and hemicellulose were similar to each other, but they were different from those of lignin; it is likely due to the difference in volatile compounds. Cellulose and hemicellulose can be gasified more rapidly producing more CO and CH₄ and less H₂ and CO₂ than lignin, and the real biomass fell in between. Biomass with more lignin produced more hydrogen than others. These differences were resulted from the relative amount of lignin, hemicellulose, and cellulose in the biomass. Linear superposition method was used to simulate the gasification characteristics of real biomass and it showed a certain linear correlation between the simulation and experimental data.     

Solvent fractionation of renewable woody feedstocks: Organosolv generation of biorefinery process streams for the production of biobased chemicals

A new organosolv biomass fractionation process (Clean Fractionation, CF) for the separation of lignocellulosic raw material into cellulose, hemicellulose and lignin has been developed. The lignocellulosic material is separated with a ternary mixture of methyl isobutyl ketone, ethanol and water in the presence of an acid promoter, which selectively dissolves lignin and hemicellulose, leaving cellulose as an undissolved solid. The resulting single phase liquor is treated with water giving an organic phase containing lignin and an aqueous phase containing hemicellulose. For woody feedstocks, the yield of the cellulose fraction across all separations averaged 47.7 wt% (±1.1). Representative separations gave cellulose fractions with average Klason lignin contents of 2.0% at acid concentrations of 0.1 M H₂SO₄ or greater. Little or no galactose, mannose or arabinose is observed in the cellulose, and at an acid concentration of 0.2 M, average xylose contents as low as 0.22% were observed. Average glucan contents for representative cellulose samples of 92.7% were observed, and rose as high as 98.2% for separations using 0.2 M H₂SO₄. Glucan contents as high as 97% were also observed if the cellulose was bleached using either a QPD or QPDE sequence. The average yield of the lignin fraction was 18.3 wt%. Representative lignin samples gave an average Klason lignin value of 91% with selected lignin samples exhibiting residual sugar levels of <0.5%. The aqueous hemicellulose fraction contains a higher level of non-sugar components, but can be purified by ion exchange chromatography.     

Physicochemical characterization and enzymatic digestibility of Chinese pennisetum pretreated with 1-ethyl-3-methylimidazolium acetate at moderate temperatures

1-ethyl-3-methylimidazolium acetate ([EMIM] AC) pretreatment at moderate temperatures (60 °C and 75 °C) was evaluated for improving hydrolysability of Chinese pennisetum, a leading candidate as an energy crop, for bioethanol production. The pretreatment caused slight carbohydrate and lignin loss but significantly changed the material physicochemical characters, such as crystallinity and surface structure. Both changes exhibited positive effects on improving the enzymatic digestibility of the Chinese pennisetum. It was observed that approximately 90% of the cellulose and 50% of the xylan in the Chinese pennisetum after pretreatment at 75 °C were converted to fermentable monosaccharides by the combined cellulases and endo-xylanase. The results suggested that Chinese pennisetum could be effectively pretreated with ([EMIM] AC) pretreatment at moderate temperatures, and the high hydrolysis yield of fermentable sugars from pretreated Chinese pennisetum could be achieved by the synergistic action of accessory xylanase in enzymatic hydrolysis by cellulases.     

The effect of temperature and hemicellulose-lignin,cellulose-lignin,and cellulose-hemicellulose on char yield from the slow pyrolysis of rice husk

In this work, the effect of temperature on the char yield of untreated rice husk, cellulose removed (hemicellulose + lignin), hemicellulose removed (cellulose + lignin), and lignin removed (cellulose + hemicellulose) is investigated. The work compares the performance of acid and alkaline hydrolysis in the context of lignin removal as well. The effect of hemicellulose-lignin, cellulose-lignin, and cellulose-hemicellulose on char yield during slow pyrolysis of rice husk is also studied. The study reveals that only low temperatures favor char yield. Alkaline hydrolysis effects better lignin removal than acid hydrolysis. The effect of hemicellulose-lignin on char yield is more than cellulose-lignin and cellulose-lignin.     

狼尾草高底物同步糖化乙醇发酵全残留物产甲烷特性研究

以汽爆狼尾草的高底物浓度乙醇发酵全残留物为底物,进行甲烷潜力测试(BMP)以及单相全混式连续搅拌反应器(CSTR)厌氧消化实验,以验证乙醇发酵全残留物的产甲烷特性及残留物中各组分在生产清洁能源甲烷时的底物贡献率。经过50 d的BMP实验,甲烷产量最终达到884 mL,相应的甲烷产率为390.6 mL/g VS,其中纤维素和半纤维素在第10天达到产气高峰,累计产气量占全残留物累计产气量的48.2%,小分子酸和酶与酵母在第2天达到产气高峰,其产气量分别占全残留物累计产气量的22.4%和26.4%。随后使用CSTR反应器进行单相厌氧消化,有机负荷从1.5 g VS/(L·d)逐渐提升至3.5 g VS/(L·d),最终获得457.1 L/kg VS的甲烷产率和47.3%的挥发性固体(VS)去除率。结果表明:狼尾草作为一种木质纤维素原料,在获得满足工业蒸馏需求的乙醇浓度后,其发酵全残留物仍可作为良好的底物通过厌氧消化制取甲烷,不仅减少工艺的环境排放负荷,而且可提高原料的利用率。     

Perennial grasses as prospective energy sources

Properties of nine composts obtained from perennial grasses for their potential use as an energy source were assessed in this study. The majority of grasses displayed high-moisture, hemicellulose, Na, K, Cl, and N contents, but low lignin content. The effect of composting was pronounced in (i) enhancement of lignin to 461.29%, fixed carbon to 49.46%, and cellulose to 35.05%; and (ii) reduction of Na to 98.77%, moisture to 93.49%, hemicellulose to 89.15%, K to 88.21%, N to 84.43%, Cl to 23.15%, and volatile matter to 12.57%. Subsequently, an increase in higher heating value to 13.90% was observed.     

酸、碱、氧化试剂与低温冻融联合预处理对高粱秸秆厌氧发酵产甲烷的影响

以高粱秸秆为原料,分别研究酸、碱、氧化试剂与低温冻融联合预处理对高粱秸秆与沼泥混合厌氧发酵产甲烷的影响.试验结果表明:经过预处理后各试验组高粱秸秆组分含量比CK对照组均有显著变化(p<0.05),木质素去除率在29.85％～41.71％之间,纤维素相对含量提高率在10.08％～17.27％之间,半纤维素去除率在1.30...     

榨糖收贮模式玉米秸秆蒸汽爆破预处理条件优化

使用蒸汽爆破法处理榨糖收贮玉米秸秆榨渣,观察不同蒸汽爆破压力和维压时间下纤维素、半纤维素、木质素（三大素）及纤维素酶水解得率的变化。榨渣三大素含量不同程度下降,半纤维素下降最多,其次是木质素,而纤维素下降最少。处理后进行的水解实验显示压力与维压时间的增加会导致纤维素水解酶得率有所提高,但压力增加对纤维素水解酶影响较小,维压时间对纤维素水解酶的影响较为突出。考虑经济成本的前提下选择1.2 MPa,10 min维压时间为最佳条件,其中纤维素含量为34.42%、半纤维素4.01%、木质素17.09%及纤维素酶水解得率为68.3%。     

Comparison of lignin,cellulose, and hemicellulose contents for biofuels utilization among 4 types of lignocellulosic crops

Lignocellulose crops serve as an excellent feedstock for biofuels because of their reduced costs and net carbon emission, and higher energy efficiency. To estimate more suitable lignocellulosic crops, we compared the contents of lignin, cellulose, and hemicellulose in miscanthus, switchgrass, sorghum, and reed (from 14 accessions according to the collection site) in the leaves and stems and expressed these as % content based on dry weight. This study shows that miscanthus, switchgrass, and sorghum are valuable lignocellulosic crops owing to the significantly lower lignin content than that in reed, among both whole crops as well as specific plant parts. Although switchgrass has been reported to possess the highest polysaccharide content among the crops examined; our results showed no difference at a 5% significance level. Our study also showed that Miscanthus sacchariflorus possesses lower lignin and higher polysaccharide content in its leaves and stalks compared to the other Miscanthus species. Furthermore, M. sacchariflorus also showed lower lignin and higher polysaccharide contents than those in switchgrass. It is possible that M. sacchariflorus is a better resource than switchgrass, although these content assays showed no differences at the 5% significance level. M. sacchariflorus plants collected in Hacheonri, Jejudo, Korea (MFJH), contained 14.12% lignin and 64.23% holocellulose, indicating that Korean miscanthus is a competitive bioenergy crop compared to foreign crops such as switchgrass, which is widely used in the United States.     

Thermogravimetric analysis as a new method to determine the lignocellulosic composition of biomass

Biomass energy uses organic matter such as wood or plants - lignocellulosic biomass - for creating heat, generating electricity and producing green oil for cars. Modern biomass energy recycles organic leftovers from forestry and agriculture, like corn stovers, rice husks, wood waste and pressed sugar cane, or uses special, fast-growing “energy crops” like willow and switchgrass, as fuel. Biomass is composed of three major components: cellulose, hemicelluloses, and lignin. Their differences in chemical structures lead to different chemical reactivities, making the relative composition in cellulose, hemicelluloses and lignin in the biomass a crucial factor for process design. In this paper thermogravimetric analysis is investigated as a new method to obtain lignin, hemicellulose and ??-cellulose contents in biomass. It is shown that this alternative method lead to comparable results than common methods used for the determination of the ??-cellulose content, with an enhancement of the accuracy in the determination of the hemicellulose content. Unfortunately, this method cannot be adopted for the determination of the lignin amount.