生物质与废塑料共热解的研究进展

文章介绍了国内外生物质热解、废塑料热解以及生物质与废塑料共热解的发展现状与趋势,概述了我国生物质能源与废塑料共热解的潜力。对生物质和废塑料共热解进行了展望,并指出了生物质和废塑料共热解研究的发展战略。     

生物质与煤共热解特性研究

选取4种典型生物质样品(麦秆、稻秆、木质素、造纸废液颗粒),将生物质样品与煤分别以1∶9、3∶7、5∶5的重量比例掺混。采用热重分析法,在相同升温速率下,对各掺混样品进行热解实验,探讨了生物质与煤热解特性的差异以及它们共热解时生物质对煤热解过程的影响。研究表明,生物质与煤的热解特性差异很大:生物质热解温度低,热解速度快,而煤相对热解速度慢,热解温度高;在生物质与煤混合热解时,总体热解特性分阶段呈现生物质和煤的热解特征;将各生物质样品与煤混合热解的实际微分曲线与按比例折算后曲线进行比较,得出实际微分曲线与折算曲线基本吻合,即生物质对煤的热解无明显影响。     

生物质与烟煤共热解特性研究

选取稻壳和松木屑等生物质,按不同比例与两种煤化程度不同的烟煤进行混合,采用热重分析的方法,研究不同生物质与烟煤单独热解和共热解的特性,研究了在自制复合型镍基催化剂条件下烟煤和松木屑的共热解特性及催化剂对焦油成分的影响.研究表明:在该实验条件下,烟煤与生物质的热解不存在重叠,烟煤的最大热解量仅为生物质的1/3 ～1/2;生物质的添加在共热解过程中对烟煤的热解起到一定的促进作用,在原料比例为50∶50时,共热解的两个失重峰逐渐变为一个;在自制镍基催化剂条件下,共热解碳转化率提高3％ ～17％,焦油得到充分裂解,极大提高了原料利用率.     

煤的理化性质对生物质和煤共热解焦油性质的影响

将木屑分别与黑山煤、神木煤以不同比例掺混,利用自制热解干馏炉进行共热解实验。比较木屑的添加对共热解焦油、水和轻质焦油产率的不同影响,结合煤和生物质的热重分析结果与煤的13C核磁共振分析表征,探讨煤的结构、煤和生物质的热化学反应特性,对共热解焦油产率和品质的作用机理。结果表明:在一定配比范围内,木屑和煤之间的交互作用明显提高了共热解焦油中轻质组分的产率,同时热解水产率低于计算值;轻质焦油中的脂肪烃组分主要由木屑和煤热解产生的烷基自由基相互化合生成;煤热解产生的芳烃类自由基由于与生物质热解产生的羟基自由基生成杂酚化合物,从而抑制了热解水的生成。     

煤与稻草共热解特性研究

用热重法研究不同煤化程度煤与稻草共热解特性.结果表明：煤与稻草共热解的TG曲线随稻草掺混比例的增加向低温区移动,趋近稻草单独热解的TG曲线;DTG曲线主要热解阶段的两个区间曲线和特征参数分别与稻草、煤单独热解的相似.通过对热解特征参数实际值和理论值的对比,稻草对共热解过程有一定的促进作用,而煤对共热解过程则没有表现出明显作用.     

棉秆与煤混合热解的特性研究

煤与生物质的混和燃烧是生物质利用的重要途径,两者的共热解是其中最重要的反应之一。为了研究煤与棉秆混合热解的影响因素,利用热重分析仪（Thermo Gravimetric Analyzer,简称TGA）,对煤与棉秆以1：1的比例掺混的混合物进行热解过程特性研究。通过对比煤和棉秆共热解过程的差异发现：煤与棉秆混合共热解过程中两者存在一定相互影响,棉秆对煤热解在温度较低的时候有一定促进作用,但随着温度的升高逐渐表现出较明显的相互抑制作用,对于生物质与煤混烧锅炉的设计和运行具有理论指导意义。     

生物质与煤的可持续性共燃

生物质是一种引人注意的在通用锅炉中补充煤燃烧的可再生燃料.煤与高达20%生物质混合在一起可成功地共燃.广泛应用煤与生物质共燃后表明有下列三个优点:(1)增加锅炉效率;(2)减少煤成本;(3)减少Nox和C02排放量.It共燃生物质可直接减少lt以上矿物COZ排放量.木材生物质不含硫.因此减少502排放量与替代的煤数量成正比.生物质含有大量碱、碱土元素和氛,它们与煤中衍生的其它气体成分如硫化合物混合在燃煤锅炉中形成不同阵列蒸汽和细粒沉积物.生物质与煤的可持续性共燃@邵本逑     

生物质与污水污泥共热解特性研究

采用热重分析仪(TGA)对生物质与城市污水污泥单独及共热解基本热解特性进行了考察,并结合测定的生物质中纤维素、半纤维素和木质素含量对共热解过程热解特性的影响规律发现:升温速率为20℃/min时,污泥单独热解分为水分析出、挥发分析出和焦炭化3个阶段;由生物质单独热解特性分析可知,松木屑热解特性最优,花生壳次之,狐尾藻最差;通过不同生物质添加量时的共热解过程考察,得知较高的生物质添加量更有利于共热解过程的进行;结合共热解特性变化与生物质组成的关系可知,含纤维素和木质素较多的松木屑与污泥共热解时有明显的协同作用发生,含木质素较多的花生壳也有较为明显的协同作用,含半纤维素较多的狐尾藻协同效果不明显。     

生物质与煤共燃污染物的研究

简要阐述了生物质与煤共燃的意义及其应用前景.在此基础上,介绍了生物质与煤共燃的分类方法,总结了生物质与煤共燃的各种污染物状况,着重分析了生物质再燃脱除NOx以及利用生物质型煤脱除SOx的研究形状,最后指出了共燃研究中存在的问题.     

生物质热解液化工艺及其影响因素

介绍了生物质的特点及生物质快速热解液化技术的一般工艺流程.综述了生物质热解过程中,反应温度、滞留时间、升温速率、反应压力、灰分、组成成分、分子结构、粒径和颗粒形状等条件对生物质热解及其产物组成和特性的影响,指出了生物质热解的技术关键.     

Investigating the release behavior of biomass and coal during the co-pyrolysis process

The release behavior of biomass and coal in the co-pyrolysis process was investigated. The release characteristics of the small molecules from 100 to 1000 °C were researched by TG-MS at the heating rate of 30 °C/min. The pyrolysis products during the co-pyrolysis process were compared with that in the separate pyrolysis process. It is found that the changes of pyrolysis products in the co-pyrolysis process are similar to that in the separate pyrolysis process. The main pyrolysis products of the biomass are released at the temperature lower than 500 °C. Some of the small molecules of Shenfu coal release at the temperature higher than 900 °C. The yields of aromatic compounds in biomasses are lower than that in Shenfu coal. In addition, most of the raw materials are pyrolyzed independently during the co-pyrolysis process. The differences between the experimental values and calculated values are slightly. With the addition of biomass, the content variations of aromatic compounds are not significant.     

Assessment of low-rank coal and biomass co-pyrolysis system coupled with gasification

To utilize low-rank coal and biomass in a highly efficient and environmental-friendly manner, a co-pyrolysis system coupled with char gasification is investigated. This system has five main units, namely, the drying and mixing, pyrolysis, cooling and separation, combustion, and gasification units, which are simulated by ASPEN plus based on experimental data. Results show that 37% of the pyrolysis char is burned to supply heat for pyrolysis and drying processes based on cascade utilization of heat energy, whereas the rest is sent to a gasifier. The sensitivity analysis is performed to investigate the impacts of steam and O₂ injection on gas composition, gasification temperature, carbon conversion efficiency, heating value of gas during gasification, and gas production efficiency. The fractions of H₂, CH₄, CO, and CO₂ demonstrate diverse variation tendencies with an increasing equivalence ratio and steam-to-char (S/C) ratio. However, carbon conversion efficiency reaches its peak of 99.91% when the equivalence ratio is approximately 4 regardless of S/C ratio. An equivalence ratio of 4 and S/C ratio of 0.15 are used as decent examples to calculate the mass balance and to simulate the overall system. Results show that 1000 kg/h coal and 500 kg/h biomass can produce 285.83 m³/h pyrolysis gas and 2580.78 m³/h gasification gas with low heating values of 8.20 and 9.746 MJ/m³, respectively.     

Interaction between biomass and different rank coals during co-pyrolysis

Effects of biomass on the pyrolytic decomposition of different rank coals were investigated by non-isothermal Thermogravimetric Analysis (TGA) method from ambient to 900 °C with a heating rate of 40 °C/min under nitrogen. Hazelnut shell (HS) which is a woody biomass species was added as much as 10 wt% to coals such as peat, lignite, bituminous coal, and anthracite to obtain coal/biomass blends for co-pyrolysis runs. Effects of HS present in the blends were evaluated regarding the apparent decomposition rates and the char yields. It was found that the addition of thermally reactive HS led to some increases in the volatilization rates of coals especially at temperatures below 500 °C. Besides, the char yields revealed unexpected variations in case of low rank coals. Although, HS addition did not play significant role on the char yields of bituminous coal and anthracite, considerable deviations from the theoretical char yields were detected in the case of peat and lignites. The presence of HS led to increasing char weight for peat, while the char weights for lignites decreased seriously. These variations were interpreted, and it can be concluded that these variations cannot be explained by simple additive behavior, and the existence of synergistic interactions should be taken into account.     

Steam gasification of co-pyrolysis chars from various types of biomass

Co-pyrolysis of two different types of biomass among apple tree branch (ATB), knotweed stem (KWS), seaweed (SW) and rice straw (RSt) was conducted to obtain co-pyrolysis char (co-char), and then the steam gasification of those co-chars was compared with the steam co-gasification of the physically mixed individual biochars to investigate the synergetic effect resulted from alkali and alkali earth metal (AAEM) in each biomass involved. It is found that the silica species in the RSt had negative effect on the activity of co-char due to the formation of alkali silicate compounds. However, combination of RSt with some non-woody biomass such as SW also showed promoting effect. In particular, the gasification of the co-char from the combination of various biomass with low or no silica content showed improved gasification efficiencies due to the synergetic effect AAEM species in the co-char from the different biomass. Therefore, the biomass selection should play a significant role in the co-pyrolysis of different biomass in the two-stage gasification system.     

辣椒秆与煤混合热解交互作用的研究

通过热重试验及动力学分析,详细研究了辣椒秆与煤的混合热解特性。结果表明,两者的混合热解存在明显交互作用,且化学反应速率常数k的大小主要由频率因子A决定。辣椒秆和煤混合热解时,第1个失重峰由原料自由水的挥发产生,第2个失重峰(305³71℃)和第3个失重峰(430371℃)和第3个失重峰(430⁵88℃)分别主要由辣椒秆和煤热解产生。第2个峰处,两者的混合促进热解,混合10%辣椒秆时促进作用尤为明显,此时试验化学反应速率常数k比理论化学反应速率常数k大两个数量级,试验失重速率明显大于理论失重速率;第3个峰处,两者的混合抑制了热解,试验的化学反应速率常数k与失重速率均小于理论值,辣椒秆的存在阻碍煤的热解。     

钙对生物质/塑料混合物共热解特性及动力学的影响

为了探究Ca2+对生物质/塑料混合物热解的影响,采用热重分析法研究了Ca2+浸渍酸洗玉米秸秆(ACS)/高密度聚乙烯(HDPE)混合物(AHM)的热解特性.结果表明,Ca2+的添加,使得AHM的初始分解温度以及第一失重峰对应温度均有所降低;此外,由于Ca2+的添加,AHM的第二失重峰对应温度基本不变,最大失重速率有所增...     

大容量煤粉锅炉生物质混燃技术探讨

针对当前发达国家正在兴起的生物质混燃发电技术,结合实际调研情况,研究分析了该技术在大容量煤粉炉中的几种典型相关系统的配置方案和国内外应用现状,指出了该技术具有高效率、低造价,同时能规模化实现二氧化碳有效减排的优势,在未来有广阔的应用前景。     

生物质水热技术研究现状及发展

生物质水热转化技术作为一种新的生物质利用技术,在亚临界或超临界水下,将生物质直接转化为高品位气态、液态和固态产物。该技术具有原料适应性广、低成本和高转化率等特点,具有很好的应用前景。文章综述了近年来生物质水热技术研究的最新进展,分别对水热液化、水热气化和水热碳化3方面内容进行分析,对目前存在的问题提出了建设性的意见。