生物质热解反应装置研究现状及展望

生物质热解是实现生物质能源化利用的重要途径,对解决日益严重的能源问题有着重要意义。着重介绍了几种典型的生物质热解反应器的研究现状,并列举了近期开发出的几种新型热解反应装置,总结了不同种类的热解反应器的工作原理及各自优缺点和适用情况。对催化热解和生物质原料预处理及反应器进行了综述,指出开发新型高效、高活性热解催化剂和加大对原料预处理技术的基础理论探索力度是未来生物质热解研究的发展方向。     

生物质快速热解装置研究进展

当今化石能源日渐枯竭和环境压力日益加重是亟待解决的问题,而生物质热解液化技术被认为是解决能源紧张的潜在方法,尤其是生物质快速热解技术。随着生物质快速热解技术与工艺不断成熟,需要快速热解装置不断放大以提高处理量,以实现生物质快速热解的工业化。生物质快速热解装置复杂且多样化,在装置的放大过程中,各系统的合理选择是难点。本文首先对生物质热解机理、快速热解过程的粒径选择和前处理进行了简述,并对快速热解流程中的进料系统、供能系统、热解反应器和快速冷凝系统4个关键系统进行了综述,着重介绍了快速热解反应器的类型及其特点,提供了该4个关键系统的选择及研究趋势。流化床反应器具有易放大、可以较好地实现自热式快速热解的优点,本文总结出流化床式反应器是目前研究的热点。在保证产品品质下,设备易放大、稳定实现自热式、流程能耗低、运行稳定安全等是快速热解装置未来的研究方向。     

生物质快速热解下行式流化床反应器研究进展

在碳中和目标下，未来发展之路是从化石能源的原料体系转变到可再生能源的原料体系。作为化石资源的重要替代品，生物质是唯一能够大规模取代化石资源的可再生碳资源。生物质快速热解技术是实现生物质资源转化为液体燃料的重要途经，其技术核心是反应器。下行式循环流化床反应器具有产物停留时间短、近平推流性能等优点，在生物质快速热解方面具有广阔的应用前景。本文介绍了流化床反应器的特点及其中试和示范/商业级装置的研究现状，详细总结了下行床反应器的特点、结构、分类及流体力学特性，并分析了目前下行床反应器放大过程中的瓶颈问题以及进一步研究的方向，为推动下行床反应器在生物质快速热解工业应用提供参考。     

生物质快速热解技术现状

生物质能源是可再生能源的重要组成部分,有丰富的资源和低污染的特点,它的开发与利用已成为21世纪研究的重要课题。本文概述了生物质转化利用的方法,并重点阐述了生物质热化学转化法中的快速热解技术,同时综述了国内外快速热解反应器的现状,以及其产物———生物油的收集与特征分析,并提出了我国在快速热解研究方面应采取的有关措施。     

生物质热解液化制备生物油技术研究进展

介绍了国内外生物质热解液化工艺、主要反应器及其应用现状;简述了生物质催化热解、生物质与煤共热解液化、微波生物质热解、热等离子体生物质热解几种新型热解工艺;并对目前生物质热解动力学研究进行了总结;对未来生物质热解液化技术的研究进行了展望。     

生物质热解制生物油及其提质研究现状

生物质能源作为可再生能源的重要组成部分,其综合高效利用在能源替代与补充、保护生态环境等方面具有重要的战略意义。生物油是生物质通过热裂解技术获得的液体产物,具有能量密度较高、环境友好、可再生及可直接输送等优点,可替代传统化石燃料推广使用,解决日益严重的能源紧缺与环境污染等问题。生物质热解制油技术的开发与利用,已成为新世纪可持续能源研究领域的重要课题之一。总结了近年来生物质热解制油技术的主要研究进展,重点关注热解反应器、催化热解技术与生物油的提质利用方面的研究,介绍了碱金属、氧化物和分子筛3种生物质热解催化剂,以及乳化、催化加氢、催化裂解、催化酯化和重整制氢5种生物质提质方法,最后对生物质热解技术的现状及发展趋势进行了总结和概括。     

生物质真空热解液化技术研究现状

对生物质真空热解液化技术特点、工艺路线、研究现状及多层真空热解磨反应器和熔盐加热真空热解反应器热解装置进行了介绍,指出该技术工业化过程中需要解决的问题是深入研究生物质的真空热解反应机理、催化真空热解反应机理以及生物质的真空热解动力学特性等.     

生物质的微波热解技术研究进展

生物能源化转化技术是当今能源领域的热点之一,生物质微波热裂解技术被广泛认为是该领域中具有超强的发展前景技术。从生物质微波热解制油、生物质微波热解制取生物炭、生物质微波热解制取合成气以及生物质微波热解多联产技术等几个方向总结了国内外生物质微波热解技术的研究现状和趋势,最后提出了生物质微波热解技术的几点建议。     

生物质的微波热解技术研究进展

生物能源化转化技术是当今能源领域的热点之一,生物质微波热裂解技术被广泛认为是该领域中具有超强的发展前景技术。从生物质微波热解制油、生物质微波热解制取生物炭、生物质微波热解制取合成气以及生物质微波热解多联产技术等几个方向总结了国内外生物质微波热解技术的研究现状和趋势,最后提出了生物质微波热解技术的几点建议。     

生物质与塑料共热解技术的分析方法及反应器研究进展

共热解技术是生物质与塑料高质化转化和高值化利用的重要方向。掌握生物质与塑料共热解分析技术及发展趋势,有利于加快对生物质、废塑料等废弃物的处理和利用。通过介绍生物质与塑料共热解技术的最新研究进展,归纳共热解过程动力学模型以及各组分之间的协同效应,讨论生物质与塑料在不同方法和反应器下共热解的表征。生物质和塑料共热解可降低热转化所需活化能,共热解协同效应可促进液态和气态产物生成。热解温度、加热速率和热解时间是影响共热解过程和产物的主要因素。文章为生物质与塑料共热解反应器类型的选择和相关技术分析提供参考。     

秸秆类生物质低温热解及混合气化的研究

生物质能源是一种重要的可再生能源,利用生物质和煤混合气化技术可以减少CO2的排放。研究了低温热解预处理对秸秆类生物质产物和气体浓度分布的影响,结果表明：经低温热解预处理后制得的生物焦的量和气体的浓度分布不仅与热解温度有关,而且与生物质种类的组成有很大的关系,考察了生物质焦和煤炭混合气化的热重试验,对混合气化反应性进行了有益的探索。     

Correlations of kinetic parameters in biomass pyrolysis with solid residue yield and lignin content

A kinetic analysis of the pyrolysis of various types of biomass (trunk, bark, leaf, shell, herbage, food dregs, and polysaccharide) as well as synthetic biomass consisting of cellulose and lignin was performed using thermogravimetric analysis data. The reaction rates of biomass pyrolysis were found to be expressed simply by a single nth-order reaction model. The kinetic parameters (frequency factor k₀, activation energy E, and reaction order n) were estimated first by differentiating the thermogravimetric curves and then by the nonlinear estimation method. The rate parameters of the pyrolysis of both 38 biomass samples and 9 synthetic biomass samples were successfully correlated in terms of the solid residue yield ω; charts are presented showing the correlations. Furthermore, a linear correlation was found between ω and the lignin content L in the woody biomass. This allows the kinetic parameters of biomass pyrolysis to be estimated using the value of ω, which is obtained from thermogravimetric measurements or estimated from the value of L for the biomass feedstock.     

Potassium catalysis in the pyrolysis behaviour of short rotation willow coppice

Short rotation willow coppice (SRC) and a synthetic biomass, a mixture of the basic biomass components (cellulose, hemicellulose and lignin), have been investigated for the influence of potassium on their pyrolysis behaviours. The willow sample was pre-treated to remove salts and metals by hydrochloric acid, and this demineralised sample was impregnated with potassium. The same type of pre-treatment was applied to components of the synthetic biomass. Characterisation was performed using thermogravimetric analysis with measurement of products by means of Fourier transform infrared spectroscopy (TGA-FTIR) and pyrolysis-gas chromatography-mass spectrometry (PY-GC-MS). A comparison of product distributions and kinetics are reported. While the general features of decomposition of SRC are described well by an additive behaviour of the individual components, there are some differences in the magnitude of the influence of potassium, and on the products produced. For both SRC and the synthetic biomass, TGA traces indicate catalytic promotion of both of the two-stages of biomass decomposition, and potassium can lower the average apparent first-order activation energy for pyrolysis by up to 50 kJ/mol. For both SRC and synthetic biomass the yields and distribution of pyrolysis products have been influenced by the presence of the catalyst. Potassium catalysed pyrolysis increases the char yields markedly and this is more pronounced for synthetic biomass than SRC. Gas evolution profiles during pyrolysis show the same general features for both SRC and synthetic biomass. Relative methane yields increase during the char formation stage of pyrolysis of the potassium doped samples. The evolution profiles of acetic acid and formaldehyde change, and these products are seen in lower relative amounts for both the demineralised samples. A greater variation in pyrolysis products is observed from the treated SRC samples compared to the different synthetic biomass samples. Furthermore, substituted phenols from lignin pyrolysis are more dominant in the pyrolysis profiles of the synthetic biomass than of the SRC, implying that the extracted lignins used in the synthetic biomass yield a greater fraction of monomeric type species than the lignocellulosic cell wall material of SRC. For both types of samples, PY-GS-MS analyses show that potassium has a significant influence on cellulose decomposition markers, not just on the formation of levoglucosan, but also other species from the non-catalysed mechanism, such as 3,4-dihydroxy-3-cyclobutene-1,2-dione.     

Prediction of Biomass Pyrolysis Mechanisms and Kinetics: Application of the Kalman Filter

In order to predict the pyrolysis mechanisms of four different biomasses (Asbos (Psilocaulon utile), Kraalbos (Galenia africane), Scholtzbos (Pteronia pallens), and palm shell), a novel method called Kalman filter was investigated and the results were compared by regression analysis. Both analyses were applied to five different generalized biomass pyrolysis models consisting of parallel and serial irreversible-reversible reaction steps. The models consisting of reversible reactions in addition to parallel pyrolysis steps demonstrated a better fit with the experimental results. The pyrolysis step from biomass to bio-oil has the highest reaction rates compared with the other pyrolysis steps defined in the models. The Kalman filter is thus defined as a promising filtering and prediction method for the estimation of detailed pyrolysis mechanisms and model parameters, using minimum experimental data.     

Liquid phase equilibrium of phenol extraction from bio-oil produced by biomass pyrolysis using thermodynamic models

Utilization of biomass as a new and renewable energy source is being actively conducted by various parties. One of the technologies for utilizing or converting biomass as an energy source is pyrolysis, to convert biomass into a more valuable product which is bio-oil. Bio-oil is a condensed liquid from the vapor phase of biomass pyrolysis such as coconut shells and coffee shells. Biomass composition consisting of hemicellulose, cellulose, and lignin will oxidize to phenol which is the main content in bio-oil. The total phenolic compounds contained in bio-oil are 47.03% (coconut shell) and 45% (coffee shell). The content of phenol compounds in corrosive bio-oils still quite high, the use of this bio-oil directly will cause various difficulties in the combustion system due to high viscosity, low calorific value, corrosivity, and instability. Phenol compounds have some benefits as one of the compounds for floor cleaners and disinfectants which are contained in bio-oil.The correlation between experimental data and calculations shows that the UNIQUAC Functional-group Activity Coefficients (UNIFAC) equilibrium model can be used to predict the liquid–liquid equilibrium in the phenol extraction process of the coconut shell pyrolysis bio-oil. While the Non-Random Two Liquid (NRTL) equilibrium model can be used to predict liquid–liquid equilibrium in the extraction process of phenol from bio-oil pyrolysis of coffee shells.     

The effect of lignin and inorganic species in biomass on pyrolysis oil yields, quality and stability

This paper investigates four reference fuels and three low lignin Lolium Festuca grasses which were subjected to pyrolysis to produce pyrolysis oils. The oils were analysed to determine their quality and stability, enabling the identification of feedstock traits which affect oil stability. Two washed feedstocks were also subjected to pyrolysis to investigate whether washing can enhance pyrolysis oil quality. It was found that the mineral matter had the dominate effect on pyrolysis in compared to lignin content, in terms of pyrolysis yields for organics, char and gases. However the higher molecular weight compounds present in the pyrolysis oil are due to the lignin derived compounds as determined by results of GPC and liquid-GC/MS. The light organic fraction also increased in yield, but reduced in water content as metals increased at the expense of the lignin content. It was found that the fresh oil and aged oil had different compound intensities/concentrations, which is due to a large number of reactions occurring when the oil is aged day by day. These findings agree with previous reports which suggest that a large amount of re-polymerisation occurs as levoglucosan yields increase during the aging progress, while hydroxyacetaldehyde decrease. In summary the paper reports a window for producing a more stable pyrolysis oil by the use of energy crops, and also show that washing of biomass can improve oil quality and stability for high ash feedstocks, but less so for the energy crops.     

生物质热转换制氢的研究进展

氢气是一种理想的洁净能源。从能源角度和环境角度考虑,发展生物质制氢技术都具有重要的意义。生物质制氢技术主要包括热化学法和生物法,其中热化学法主要是将生物质气化或液化,再进行重整和水蒸气变换反应,获得氢气。本文综述了生物质热化学转化(包括气化、超临界水气化、热裂解等)制氢技术的研究进展,并对典型的制氢技术作了评述和展望。     

Comparison of the thermal reactivities of isolated lignin and holocellulose during pyrolysis

Woody shells of Turkish hazelnuts which are rich in lignin content offer an important potential as a renewable energy source. Hence, this study focuses on the investigation of the thermal reactivities of the real macromolecular ingredients of this biomass species. Hazelnut shells were treated with chemicals to isolate its holocellulose (hemicelluloses + cellulose) and lignin. Scanning Electron Microscopy (SEM) images revealed the significant differences between the physical features of the untreated biomass and its isolated ingredients. Thermal properties of the biomass and these ingredients were examined by Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) techniques under non-isothermal pyrolysis conditions from ambient to 900 °C. It was found that unlike holocellulose, lignin slowly decomposes in a wider temperature range, and its decomposition is associated with exothermic heat flow. It was also concluded that the hemicellulosics in holocellulose have very important effects with respect to the char yield and the exothermicity of the process. Besides, inorganics in biomass play a catalytic role during pyrolysis. The activation energies calculated according to Borchardt-Daniels' kinetic model were 64.8 and 51.8 kJ/mol for the pyrolysis of holocellulose and lignin, respectively, and each of them is higher than that for the untreated biomass.     

Kinetic analyses of biomass pyrolysis using the distributed activation energy model

The pyrolysis behaviors of several agricultural residues have been investigated by using thermogravimetric analysis. The evolving rates of the gaseous products during the pyrolysis such as H₂, CH₄, H₂O, CO and CO₂ were also measured by the TG-MS techniques. Without any assumption and mathematical fitting, we could obtain the very proper kinetic parameters (the distribution curve of activation energy, f(E), and the activation energy dependent frequency factor, k₀(E)) of biomass pyrolysis by utilizing the distributed activation energy model (DAEM) proposed by Miura and Maki [Miura K, Maki T. Energ Fuel 1998;12:864]. The peaks of f(E) curve for rice straw, rice husk, corncob and cellulose were found to be 170, 174, 183, and 185 kJ/mol, respectively. The k₀ value increased from an order of 10¹¹ to an order of 10¹⁸ s⁻¹, while E increased from 120 to 250 kJ/mol. The catalytic effects of alkali and alkaline earth metals during the pyrolysis play a major role in the variation of f(E) curve among the different biomass species.     

含油污泥热解技术的研究进展

含油污泥作为石油行业的的主要污染物之一,实现资源化、无害化的处理是目前的主要目标。热解技术作为能量回收型的处理技术,其特点是处理较彻底,油气和残渣都可被回收利用。主要介绍了含油污泥的热解处理技术,分析了温度、时间、升温速率和催化剂对含油污泥热解的影响,并对热解残渣的资源化回收利用进行了总结。