生物质热化学液化技术研究进展

随着化石燃料可开采量的减少和人类对全球性环境问题的关注，生物质作为一种可再生能源，由于资源丰富，分布广泛，燃烧过程对环境的低污染性，CO2的净零排放等特性日益成为国内外众多学者研究的热点课题之一。生物质转化技术可分为生物法和热化学转化法，后者主要有气化、热解、高压液化及与煤共处理等工艺。其中生物质热化学液化由于比气化能得到更有价值的液体产物，操作温度比热解低，因而作为一项资源高效利用的新工艺日益受到重视。综述了近五年来生物质热化学液化技术方面的最新进展，提出了今后的研究动态与发展方向，并针对我国现状提出应采取的对策。     

生物质能合理高效规模化利用和转化技术的选择

生物质能的规模化利用和转化技术有不同的适用对象和范围,合理选择才能确保生物质能项目的可持续发展。从生物质能特性、工艺特点、环保性能、经济效益、市场需求和规模化生产六个方面综合考虑、统筹优化,提出生物质能合理高效利用和转化技术选择的基本选型原则。即生物质能利用和转化前后,最佳选择为全过程净热值为正,且越高越好;生物质能货币价值必须增值,并能承受一定的原料价格合理上涨风险;生物质能转化和利用过程无二次污染,产品低污染或无污染;产品畅销、市场容量大,副产物可就近资源化利用;在20～50km内可收集到的生物质原料可以满足最佳利用和转化规模的需求。根据选型原则统筹考虑,对农村生物质能资源、企业废弃生物质能资源、高含水生物质能资源、不可食用油脂和城市生活垃圾资源的合理高效规模化利用和转化技术进行选择:农村养殖业粪便采用沼气综合利用技术进行转化;农林废弃物采用快速热解技术规模化转化;城市和社区生活垃圾以及农林产品加工的相关企业生物质废弃物采用气化技术转化用作燃气;水生植物、藻类、城郊养殖业粪便和二次有机污泥液化等高含水的生物质能采用加压液化技术制取生物油,以消除污染;不可食用油脂采用酯化技术生产生物柴油。     

生物质能利用方式的分析比较

简要分析了几种生物质能利用方式的技术性、经济性和社会性特征。通过比较，认为通过热化学法或生化法将生物质转化为液态或气态燃料即可提升生物质能的能量品质，又可大大拓展生物质能的使用范围，是生物质能利用的主要方式。其中，生化法由于其近于零污染的特性而将成为生物质能利用的首选方式。     

利用微藻热化学液化制备生物油的研究进展

微藻是制备生物质液体燃料的良好材料,利用微藻热化学液化制备生物油在环保和能源供应方向都具有非常重要的意义。目前国内外研究者主要采用快速热解液化和直接液化两种热化学转化技术进行以微藻为原料制备生物油的研究。快速热解生产过程在常压下进行,工艺简单、成本低、反应迅速、燃料油收率高、装置容易大型化,是目前最具开发潜力的生物质液化技术之一。但快速热解需要对原料进行干燥和粉碎等预处理,微藻含水率极高,会消耗大量的能量,使快速热解技术在以微藻为原料制备生物油方面受到限制。直接液化技术反应温度较快速热解低,原料无需烘干和粉碎等高耗能预处理过程,且能产生更优质的生物油,将会是微藻热化学液化制备生物油发展的主流方向,极具工业化前景。国内外研究者还尝试利用超临界液化、共液化、热化学催化液化、微波裂解液化等多种新型液化工艺进行微藻热化学液化制备生物油的实验研究。今后的主要研究方向应是将热化学液化原理研究、生产工艺开发、反应器研发、反应条件优化、产品精制等有机地结合起来,进行深入研究。同时应努力节约成本、降低能耗。     

生物质热解液化技术研究与发展趋势

介绍了生物质热解液化技术,总结了该项技术在原料预处理、热解工艺和生物油分离精制3个方面的最新研究成果。在原料预处理方面,介绍了微波干燥、烘焙和酸洗3种方法;在热解工艺方面,介绍了催化热解和混合热解两种新工艺;在生物油分离精制方面,介绍了催化加氢、催化裂解、催化酯化、乳化燃油和分离提纯5种新技术,并分析展望了生物质热解液化技术的产业化发展趋势。     

生物质热解液化技术研究现状

对生物质热解液化技术及其液化机理进行阐述,并介绍国内外生物质热解反应器类型及其发展现状,分析热解过程中的影响因素。生物质热解液化技术很大程度上能缓解当今社会的能源危机和环境污染,是人类开发可再生资源的一种有效途径。     

生物质热解液化技术经济分析

我国生物质资源十分丰富，但主要以各类农业残余废弃物为主，其特点是能量密度低、分布不集中，如果采用热解液化技术在产地将其先分散转化成生物油，然后再对生物油进行应用或再加工，则就避免了大规模收集和长距离运输生物质所带来的巨大困难。研究分析表明：热解液化设备的规模以每小时可处理2t农业残余废弃物较为适宜，且这种技术在我国具有良好的市场应用前景。     

生物质能利用技术现状及进展

在阐述生物质能源开发利用意义的基础上,针对现有的生物质能利用技术的发展现状进行了综合分析,主要介绍了生物质燃烧技术、生物质气化技术和生物质液化技术以及生物化学转化过程,指出了在目前形势下,大力发展生物质能利用技术具有广阔的前景.     

国内外生物质热解液化装置的研发进展

生物质热解技术是最具有发展潜力的生物质能技术之一。而对其热解装置的研究又是热解技术研究的核心内容。该文针对国内外生物质热解液化装置的研发现状进行了较全面地介绍并提出了存在的问题及可能的解决方案,对发展我国的生物质液化技术有指导意义。     

我国生物质热解液化技术的现状

文章主要阐述了我国生物质热解液化技术的研究现状，包括现有的热裂解液化装置、反应动力学模型、已检测出的不同原料裂解产生的生物油成分及其物理特性分析，提出了生物油精制的必要性和未来需要研究的问题。     

A comprehensive review on lignocellulosic biomass biorefinery for sustainable biofuel production

The increasingly severe environmental pollution and energy shortage issues have demanded the production of renewable and sustainable biofuels to replace conventional fossil fuels. Lignocellulosic (LC) biomass as an abundant feedstock for second-generation biofuel production can help overcome the shortcomings of first-generation biofuels related to the “food versus fuel” debate and feedstock availability. Embracing the “circular bioeconomy” concept, an integrated biorefinery platform of LC biomass can be performed by employing different conversion technologies to obtain multiple valuable products. This review provides an overview of the principles and applications of thermochemical processes (pyrolysis, torrefaction, hydrothermal liquefaction, and gasification) and biochemical processes (pretreatment technologies, enzyme hydrolysis, biochemical conversion processes) involved in LC biomass biorefinery for potential biofuel applications. The engineering perspective of LC biofuel production on separate hydrolysis and fermentation (SHF), simultaneous saccharification and fermentation (SSF), simultaneous saccharification and co-fermentation (SSCF), and consolidated bioprocessing (CBP) were also discussed.     

生物质热加工液化技术评述

介绍了生物质热加工液化技术中的各种热裂解液化和高压液化工艺,包括流化床、涡流烧蚀反应器、真空快速裂解反应器以及高压釜、半连续固定床等装置的工作原理和生产工艺,分析它们各自的优点和存在的问题,着重讨论了各种工艺提高生物原油产率的措施以及精制生物原油可替代柴油作为车用轻质燃油的方法,指出降低生物原油的生产成本,扩大生产规模是热加工液化的发展方向。     

Techno-economic modelling of biomass flash pyrolysis and upgrading systems

The thermochemical conversion of biomass by flash pyrolysis or liquefaction produces a crude liquid that can be used directly to substitute for conventional fossil fuels or upgraded to a higher quality fuel. Both the crude and upgraded products may be utilised for power generation. A computer program is used to model the flash pyrolysis of biomass with subsequent upgrading and refining of the crude liquid products to produce higher value and more marketable liquid fuel products. The structure and scope of the program, the hydrotreating model and the development of an energy self-sufficient flash pyrolysis model are detailed. The program is used to assess and compare the economic and technical opportunities for upgrading crude pyrolysis liquids into the higher quality fuels demanded by more advanced technologies.     

Biorefineries: Current activities and future developments

This paper reviews the current refuel valorization facilities as well as the future importance of biorefineries. A biorefinery is a facility that integrates biomass conversion processes and equipment to produce fuels, power, and chemicals from biomass. Biorefineries combine the necessary technologies of the biorenewable raw materials with those of chemical intermediates and final products. Char production by pyrolysis, bio-oil production by pyrolysis, gaseous fuels from biomass, Fischer–Tropsch liquids from biomass, hydrothermal liquefaction of biomass, supercritical liquefaction, and biochemical processes of biomass are studied and concluded in this review. Upgraded bio-oil from biomass pyrolysis can be used in vehicle engines as fuel.     

Main routes for the thermo-conversion of biomass into fuels and chemicals. Part 1: Pyrolysis systems

Since the energy crises of the 1970s, many countries have become interest in biomass as a fuel source to expand the development of domestic and renewable energy sources and reduce the environmental impacts of energy production. Biomass is used to meet a variety of energy needs, including generating electricity, heating homes, fueling vehicles and providing process heat for industrial facilities. The methods available for energy production from biomass can be divided into two main categories: thermo-chemical and biological conversion routes. There are several thermo-chemical routes for biomass-based energy production, such as direct combustion, liquefaction, pyrolysis, supercritical water extraction, gasification, air–steam gasification and so on. The pyrolysis is thermal degradation of biomass by heat in the absence of oxygen, which results in the production of charcoal (solid), bio-oil (liquid), and fuel gas products. Pyrolysis liquid is referred to in the literature by terms such as pyrolysis oil, bio-oil, bio-crude oil, bio-fuel oil, wood liquid, wood oil, liquid smoke, wood distillates, pyroligneous tar, and pyroligneous acid. Bio-oil can be used as a fuel in boilers, diesel engines or gas turbines for heat and electricity generation.     

生物质热解液化反应塔中最小携带流速的可视化试验验证

生物质颗粒的最小流化速度是生物质快速热解液化工艺最重要的控制参数之一,准确掌握各种因素对最小携带流速的影响规律,对于保证充足的热解时间、提高生物质热解液化率是十分关键的,文章提出了生物质循环流化床快速热解反应塔中最小携带流速的预测方法;揭示了最小流化速度随生物质粒径和颗粒密度的变化规律,并通过可视化试验对预测结果进行了初步验证。     

Hydrothermal liquefaction of biomass: A review of subcritical water technologies

This article reviews the hydrothermal liquefaction of biomass with the aim of describing the current status of the technology. Hydrothermal liquefaction is a medium-temperature, high-pressure thermochemical process, which produces a liquid product, often called bio-oil or bi-crude. During the hydrothermal liquefaction process, the macromolecules of the biomass are first hydrolyzed and/or degraded into smaller molecules. Many of the produced molecules are unstable and reactive and can recombine into larger ones. During this process, a substantial part of the oxygen in the biomass is removed by dehydration or decarboxylation. The chemical properties of bio-oil are highly dependent of the biomass substrate composition. Biomass constitutes of various components such as protein; carbohydrates, lignin and fat, and each of them produce distinct spectra of compounds during hydrothermal liquefaction. In spite of the potential for hydrothermal production of renewable fuels, only a few hydrothermal technologies have so far gone beyond lab- or bench-scale.