酸洗脱灰及离子交换对低阶煤热溶剂提质分离的影响

采用酸洗脱灰、酸洗和Na/Co离子交换对两种低阶煤(MM和LY)进行预处理,然后以1-甲基萘为溶剂对预处理煤进行热溶剂提质萃取,把煤分成提质煤(UC)、高分子量萃取物(deposit)和低分子量萃取物(soluble)3种主要固体组分,以及少量水和气体产物。结果表明,通过脱灰和离子交换均提高了两种萃取物的收率及碳含量,并明显促进了煤中含氧官能团的脱除。脱灰后MM煤的高分子量萃取物收率从3.5%增加到9.5%,Na离子交换LY的低分子量萃取物的碳含量高达85.3%、氧含量低于6.4%。离子交换对两种萃取物的物理化学性质有明显的影响,Na+的影响尤为显著。酸洗脱灰和离子交换对低阶煤热溶剂提质萃取有明显促进作用。     

低阶煤温和液化-炭化耦合转化过程及产物性质

基于低阶煤温和液化-炭化耦合工艺,主要研究了390-450℃液化温度条件下的产物分布特征,分析了所得液相产物和半焦的性质。结果表明,有机液相产率达23.44%-33.26%(干燥无灰基煤为基准),半焦产率达49.56%-68.72%(干燥无灰基煤为基准);所得液相产物水含量为1.30%-2.49%,不含固体颗粒,有机液相产物的正己烷可溶物含量达98.95%以上;所得半焦碳含量高达87.87%-93.45%(干燥无灰基),部分半焦产物具有强黏结性的特点,并且黏结性与其沥青质含量相关。     

低阶煤与生物质在热溶剂提质萃取过程中的相互作用（英文）

作者前期工作中提出了一种针对生物质废弃物或低阶煤的热溶提质萃取方法,该方法可以在350℃下实现生物质或低阶煤的提质及多级分离,获得高附加值的萃取物。与生物质的热溶提质萃取比较,低阶煤的萃取物收率较低。本研究提出对生物质和低阶煤混合物进行热溶提质萃取,通过两者的物理化学相互作用,来提高其萃取收率。研究结果表明,对两者混合物热溶剂提质分离得到萃取物的产率及元素组成与理论计算结果略有不同,理论计算结果是假设生物质与煤之间无交互作用而得到的。煤中的矿物质对生物质热分解起催化作用,导致收率有所增加。煤、生物质及其混合物通过热溶剂提质分离得到的萃取物的元素组成、分子量分布、化学结构、热分解和热塑性非常相似。总体而言,低阶煤与生物质在热溶剂提质萃取过程的交互作用较小。但是,本研究证明了热溶提质萃取方法不仅适用于煤或生物质,也适用于它们的混合物。这意味着热溶剂提质萃取法可以在不改变任何工艺条件参数的情况下,以煤、生物质及其混合物作为原料。     

低阶煤与生物质在热溶剂提质萃取过程中的相互作用

作者前期工作中提出了一种针对生物质废弃物或低阶煤的热溶提质萃取方法，该方法可以在350℃下实现生物质或低阶煤的提质及多级分离，获得高附加值的萃取物。与生物质的热溶提质萃取比较，低阶煤的萃取物收率较低。本研究提出对生物质和低阶煤混合物进行热溶提质萃取，通过两者的物理化学相互作用，来提高其萃取收率。研究结果表明，对两者混合物热溶剂提质分离得到萃取物的产率及元素组成与理论计算结果略有不同，理论计算结果是假设生物质与煤之间无交互作用而得到的。煤中的矿物质对生物质热分解起催化作用，导致收率有所增加。煤、生物质及其混合物通过热溶剂提质分离得到的萃取物的元素组成、分子量分布、化学结构、热分解和热塑性非常相似。总体而言，低阶煤与生物质在热溶剂提质萃取过程的交互作用较小。但是，本研究证明了热溶提质萃取方法不仅适用于煤或生物质，也适用于它们的混合物。这意味着热溶剂提质萃取法可以在不改变任何工艺条件参数的情况下，以煤、生物质及其混合物作为原料。     

煤液化重质产物压力流体萃取过程的研究 Ⅰ.萃取物料和溶剂的选择

实验室研究结果表明,压力流体萃取是从煤液中分离矿物质和回收低挥发度煤衍生液体产物的有效技术。在萃取氢-煤法减压蒸馏釜液或水力旋风分离器底流物时,这些重质物料可分离成灰分在0.05%以下的低灰液体产品和灰分达60%以上的富灰残渣。以溶剂精炼煤法所得的滤料作为萃取原料时,也得到了良好的结果。分别采用正壬烷、甲苯,乙苯、对二甲苯、四氢呋喃、对甲酚和吡啶作为压力流体萃取用的溶剂,在100大气压和350℃条件下萃取时,上述溶剂中芳香烃是适宜的溶剂。用甲苯、乙苯或对二甲苯萃取时,萃取物收率均非常接近于用吡啶的萃取物收率,而且比用相应溶剂在索氏萃取器中所得为高。可以设想,在压力流体萃取过程中,有一部分甲苯不溶物转化成甲苯可溶物。     

溶剂特性对淖毛湖煤加氢液化中间产物反应行为的影响

为探究溶剂特性对煤加氢液化中间产物反应行为的影响,以新疆淖毛湖煤作为原料,四氢萘、循环溶剂及十氢萘作为供氢溶剂,在高压搅拌釜中进行直接加氢液化实验,并运用电子顺磁共振手段分析了中间产物-沥青质的自由基浓度的变化。结果表明,四氢萘溶剂中沥青质随反应温度的升高在大量生成的同时又被转化,产率从290℃的12.92%到350℃的最大34.13%再到430℃的15.98%;循环溶剂中沥青质产率先持续上升,290℃即有31.89%,400℃达到最大47.96%,之后由于结焦反应降低至33.90%。十氢萘溶剂中沥青质产率变化趋势与四氢萘一致。三种溶剂中沥青质自由基浓度的变化趋势相同,均在350℃达到最大值,分别是1.778×10¹⁸、2.323×10¹⁸和1.930×10¹⁸/g,整体上看循环溶剂数值要高于四氢萘,十氢萘介于两者之间。而四氢萘及循环溶剂中沥青质的g值在2.00323-2.00403,变化趋势与液化气体产物中CO_x含量变化相吻合。     

生物质“热溶富碳”及其产物利用

生物质“热溶富碳”(Thermal Dissolution based Carbon Enrichment, TDCE)是利用非/弱极性有机溶剂在温和条件(350℃、氮气氛围)下对木质纤维素类生物质废弃物进行热萃取,经过一系列脱氧和芳构化反应,获得的目标固体产物Soluble和Deposit具有无水、无灰、高热值等优点,同时该技术还具有溶剂不参与化学反应,可回收循环利用的优势。因此,热溶富碳是实现生物质能源转化的有效途径之一。本综述首先介绍了目前生物质利用的各类方式;然后重点综述了生物质热溶富碳影响因素、反应机理以及产物利用途径。在“碳中和”的国家战略背景下,生物质热溶富碳技术具有较明显的经济价值和社会意义。     

低温煤焦油常渣C5沥青质的分离与表征

从低温煤焦油中蒸馏提取出大于350℃的常渣,以正戊烷、正戊烷+5%乙醇、正戊烷+5%异丙醇三种溶剂沉淀沥青质。通过1H-NMR、13C-NMR、傅里叶变换离子回旋共振质谱仪(FT-ICR MS)、元素分析和相对分子量测定等手段对重组分沥青质的结构参数、杂原子化合物的分布等方面进行了分析,构建含杂原子的平均分子结构模型。结果表明,乙醇和异丙醇的加入可以显著降低C5-沥青质的收率,所得沥青质的芳香性增强,平均分子量增大,为更高缩合度的具有较短侧链的结构;极性溶剂的加入没有改变沥青质中杂原子化合物的类型,但是O1和O2中一部分低缩合度的化合物转移到可溶质中,O3-O6化合物的相对丰度增大,表明混合溶剂有利于萃取低缩合度的化合物。     

兖州煤与大庆减压渣油在共处理过程中的相互作用Ⅱ.甲苯可溶重质产物族组成和分子量的变化规律

通过对兖州煤与大庆减压渣油共处理重质产物的组成、分子量及分子量分布的考察,研究了甲苯可溶重质产物组成性质随反应条件的变化规律.结果表明,在较低反应温度(375～425℃)下,共处理减缓了重质产物中饱和份的转化,同时使树脂和沥青质含量降低;在较高反应温度(450℃)下,由于煤与渣油的裂解程度增加,共处理与单独处理重质产物中饱和份含量均降为0,共处理重质产物的树脂+沥青质含量显著增加.共处理使重质产物的分子量增大,且随着反应温度的升高,重质产物的分子量逐渐减小,同时分子量分布逐渐变窄.     

大雁褐煤超临界水萃取研究

在间歇式高压釜中进行了大雁褐煤的超临界水萃取研究。考察了萃取温度、时间、溶剂量及供氢溶剂等参数对过程产率及产品组成的影响。结果表明,褐煤超临界水萃取过程的转化率及产率受多种因素的影响,得到的萃取物组成也随条件变化而改变,过程中产生的气体主要成分为CO_2。经水萃取后的褐煤具有比原煤低的水分、低氧含量、高碳含量及一定的挥发分,即质量得到了提高。     

生物质灰添加对无烟煤煤焦气化特性的影响

以遵义无烟煤煤焦为气化原料,以稻草灰和棉秆灰为生物质灰添加剂,基于热重分析仪开展焦样-CO_2等温气化实验,以探究生物质灰添加对煤焦气化反应特性的影响,并基于气化过程焦样固体结构演变对其进行关联解释。研究表明,稻草灰和棉杆灰的添加有利于提高煤焦气化反应活性,这主要归因于生物质灰添加有利于气化过程煤焦活性矿物质含量增加和碳结构有序度降低。且稻草灰和棉秆灰的添加对焦样气化反应活性的增加幅度随气化温度升高而减小,这可解释为生物质灰添加对气化过程煤焦活性矿物质含量增加和碳结构有序度降低的幅度随气化温度升高而减小。此外,棉秆灰对煤焦气化反应活性的促进作用较稻草灰更为显著,这主要由于棉杆灰的添加对气化半焦中活性AAEM含量的增加作用以及碳结构石墨化进程的抑制作用更加明显。     

A sustainable approach for soil amendment; available plant nutrients in rice straws

The main aim of this study is to estimate the potential of mitigating the soil degradation by the utilization of rice straws, In every crop huge quantity of crop residue is generated along with the food grains. Only small part of the crop residue is used as cattle feed and other applications, significant quantity of these crop residues are either left unutilized or disposed by means of open field burning by the farmers, because other disposal options are not economically viable for the farmers. Consequences of open field burning of crop residues in India are, contribution of particulate matter in the atmosphere, emission of CO₂, CO, NH₃, NO_x, SO_x, and smog. On burning of crop residue heat produced is also accounted for the damage of microbes and other nutrients also present on the top layer of the soil, loss of organic carbon; it adversely affects soil fertility and productivity. It has a great economic potential as it contains high carbon content and significant amount of other essential plant nutrients which are required for plant growth. Sun dried rice straw samples were collected and analysed for primary nutrients (C, H, S, N, P₂O₅ and K₂O) required for plant growth. Moisture content was 11.70%, Elemental analysis of paddy straw on dry basis was found C = 36.04%, H = 5.25%, S = 0.28% & N = 0.69% P₂O₅ = 0.43% and K₂O = 0.64% in the kharif season 2021. These elements were quantified by using different advanced analytical techniques.     

稻秆的烘焙预处理及其固体产物的气化反应性能

稻秆资源分散、水分含量高且密度低、热值低,烘焙预处理技术能够降低收集运输的物流成本,获得的固体产物能量密度高、可磨性好,适于气流床气化。在固定床热解装置上通N₂保护,稻秆分别经过200℃、250℃、300℃烘焙30min,得到的固体产物在热重分析仪中与CO₂进行非等温气化实验,升温速率20℃/min,终温1200℃。实验结果表明,稻秆烘焙产物以固体剩余物和不凝结气体为主,还有少量可凝结液体(水分和焦油)。气体产物中CO₂所占比例超过80%,其次为CO和微量CH₄。预处理温度越高,固体剩余物越少、气体产物越多,可凝结性液体变化不大。稻秆烘焙过程的能量产率为40%~60%,随温度升高经历了急剧下降和缓慢降低两个阶段。固体剩余物的可磨性相比原始稻秆有了很大的提高,易于制细粉用于气流床气化。烘焙温度升高,所得固体产物气化反应性提高。根据Coats-Redfern法确定烘焙稻秆焦-CO₂气化反应机理符合二维扩散模型,求得反应活化能73kJ/mol~88kJ/mol。     

Energy potential and thermogravimetric study of pyrolysis kinetics of biomass wastes

The use of agricultural wastes for energy conversion has been widely studied as renewable and carbon neutral energy sources. This paper aims to evaluate the energetic potential of six agricultural wastes—sugarcane bagasse, bean pods, corn stover, pineapple crown leaves, white cotton and natural coloured cotton stalks, through their characterization and pyrolysis kinetic study. The energetic potential of biomasses was evaluated by ultimate and proximate analysis, higher heating value (HHV), apparent density, and kinetic parameters of conversion and apparent activation energy (E_a) determined by Model-Free kinetics though thermogravimetric analysis data. The results indicate energetic density for dry basis biomasses, such as moisture content less than 7%, volatiles higher than 77% and moderate ash content. The HHVs were higher for the biomass with low O:C ratio. The E_a values increased with increasing O:C ratio and were also influenced by the biomass ash content. Among the studied biomasses, PCL are less explored for energy application, although the results confirm its potential for application in thermochemical processes such as pyrolysis or combustion.

     

弱还原气氛下水稻秸秆对晋城无烟煤的助熔机理

以高灰熔点的晋城无烟煤和水稻秸秆为研究对象,通过CaO-Al_2O_3-SiO_2三元相图、X射线衍射分析(XRD)和扫描电镜耦合X射线能谱分析(SEM-EDX)研究了弱还原气氛下水稻秸秆对晋城无烟煤的助熔机理。随着水稻秸秆添加比例的增加,灰熔融特征温度呈下降趋势,灰中碱性氧化物CaO、Na_2O和K_2O含量增多,结渣指数Rb/a值在0.20-0.69;当水稻秸秆添加量为20%(质量分数)时,流动温度(FT)降低至1 369℃,可满足气化炉液态排渣的要求;水稻秸秆的添加降低了灰中液相出现的温度,增加了液相物质出现的比例和几率,使灰更易发生熔融;混合灰中所形成的钠长石等低熔点矿物质以及钙长石、石英和莫来石所形成的低温共熔物导致灰熔点降低。     

Enzymatic hydrolysis of ammonia-treated rice straw

Rice straw pretreated with liquid anhydrous ammonia was hydrolyzed with cellulase, cellobiase, and hemicellulase. Ammonia-processing conditions were 1.5 g of NH₃/g of dry matter, 85°C, and several sample moisture contents. There were four ammonia addition time (min)-processing time (min) combinations. Sugars produced were analyzed as reducing sugars (dinitrosalicylic acid method) and by high-performance liquid chromatography. Monomeric sugars increased from 11% in the nontreated rice straw to 61% of theoretical in treated rice straw (79.2% conversion as reducing sugars). Production of monosaccharides was greater at higher moisture content and was processing time dependent. Glucose was the monosaccharide produced in greater amounts, 56.0%, followed by xylose, arabinose, and fructose, with 35.8, 6.6, and 1.4%, respectively.     

松木粉气流床气化特性实验研究

在气流床气化实验装置上进行了松木粉气化特性的研究。考察了温度、氧当量比、水蒸气配比对气体产物的成分、气化特性和固体产物的微观形态及成分的影响,结果表明,随着温度的升高,CO与H₂浓度显著升高,CO₂与CH₄浓度明显下降,碳转化率、产气率、产气热值有所提高;氧当量比从0.2上升至0.5时,CO与H₂浓度降低超过10%,CO₂浓度则上升100%以上,碳转化率提高至92.9%,产气率有所上升,而产气热值则降低超过20%;水蒸气配比从0增大至0.58时,H₂/CO体积比由0.63提高为1.40,碳转化率、产气率和产气热值均呈现先增大后减小趋势。由SEM照片可以看出,固体残渣主要由类球状或块状结构与纤维团聚结构两部分组成。温度升高使残渣颗粒由呈现不规则形状逐渐向球形转化,氧当量比的增大使残渣中类球状颗粒表面孔洞与裂缝明显增多直至破碎。     

Co-pyrolysis of waste polymers with coal

Co-pyrolysis of coal with waste polymers in a stationary quartz reactor was performed. Mass balance of the process was evaluated and properties of products were characterized. The main product (solid carbonaceous residue) exhibits low ash and sulfur contents and, from the point of view of application, satisfactory surface properties. Therefore, the solid residue is suitable as a smokeless fuel or as an industrial sorbent. The by-products were tar and gas. The tar may be used as a source of chemicals or a low-sulfur heating oil, the gas was highly calorific, therefore it may serve as a heating gas for energetical purposes.     

生物质固体成型燃料热值和碳元素预测模型的建立

建立生物质固体成型燃料热值和碳元素预测模型。利用秸秆类生物质固体成型燃料的测试数据,以工业分析中的水分、灰分、挥发分和固定碳含量指标为4个自变量,分别以低位热值、高位热值和碳元素分析为因变量,通过多元线性回归模型(MLR)方法建立多元线性回归预测模型。内部检验和外部检验说明3组模型在应用域范围内均具有理想的预测能力,拟合效果良好,其中高位热值预测模型的R^2和R^2_(prep)分别为0.900和0.730,与已有研究相比,相对残差范围减小为–2.59%~2.26%,可为工业用途的生物质固体成型燃料的热值和碳元素分析快速做出反映。     

Environmental application of rice straw in energy production and potential adsorption of uranium and heavy metals

The sustainable development of agricultural waste is nowadays a main strategy in producing neutral CO₂ energy and metal removal technologies. In Egypt, large amounts of rice straw are annually burnt in the open air causing severe air pollution that could be directed to co-firing and adsorption technologies. On bench scale, rice straw was positively contributed in a clean and smokeless co-firing process with methanol due to the oxidizing effect of the alcohol. The co-firing temperature control is vital to develop the adsorptive character of the residual ash and to avoid prolonged time needed to improve the physical properties of the rice straw if applied directly as a biosorbent. The consumed methanol in the process ranges from 0.15 to 0.3 liter per each kg of straw depending on its compaction. The grossed heat value from such process may drive steam generator for electricity. The residual ash was subsequently cross-linked in uranium and heavy metals adsorption tests from solutions. The porous texture of the residual ash and the amorphous nature of the silica along with potassium content provide a suitable condition for uranium immobilization especially if phosphorus or vanadium exist. The resulted chemical precipitate is analogues in composition to meta-ankoleite (KUO₂PO₄·3H₂O) or hydrated carnotite (K₂(UO₂)₂V₂O₈)·1-3H₂O respectively. The XRD data of the latter form show an enhancement in crystallinity of the amorphous precipitate with the heated samples.