生物质发电气化过程的机理建模分析

生物质气化发电的关键技术是生物质气化技术,目前国内外对生物质气化发电技术的研究,还缺乏通用的气化模型和方法来模拟气化过程的特性,不能准确地确定生物质燃气的组分和热值等参数,难以提供气化发电系统的可靠数据.最常用的气化过程建模方法是建立机理模型,文章在重点分析了气化过程机理的基础上,把气化模型划分为平衡模型和动态模型两大类,并比较了各模型的优缺点.     

生物质气化焦油脱除过程参数优化方法

焦油是生物质气化过程中的有害产物,它会降低燃气品质,对气化设备及后续用气设备产生危害.本文通过对生物质气化过程中影响焦油生成量的因素进行分析,依据最小二乘曲线拟合原理和目标规划理论建立了生物质料木屑气化过程焦油脱除的参数优化模型,在此基础上采用遗传算法对焦油脱除过程优化模型进行参数寻优.计算结果表明,当气化温度为796.6℃、当量比为0.203时,木屑气化的焦油生成量最小.     

户用型生物质气化炉主要技术性能的试验研究

在实验台上针对改进型户用生物质气化炉进行了主要技术性能的试验研究,其中包括生物质原料、鼓风量、气化强度等参数对气化性能的影响,净化装置的脱除效果研究以及焦油回流装置对气化指标的影响等。实验表明,生物质原料的有关参数对气化性能有明显影响;鼓风量是气化炉生产负荷最简单迅速的调节手段之一,鼓风量存在一个最佳运行的鼓风量范围;户用型气化炉设计的净化装置脱除效果显著;焦油回流装置设计合理,提高了燃气品质和气化效果。     

生物质气化发电机技术（1）气化发电的工作原理及工艺流程

１气化发电工作原理生物质气化发电技术的基本原理是把生物质转化为可燃气,再利用可燃气推动燃气发电设备进行发电。它既能解决生物质难于燃用而且分布分散的缺点,又可以充分发挥燃气发电技术设备紧凑而且污染少的优点,所以气化发电是生物质能最有效最洁净的利用方法之一。气化发电过程包括３个方面：一是生物质气化,把固体生物质转化为气体燃料;二是气体净化,气化出来的燃气都含有一定的杂质,包括灰分、焦炭和焦油等,需经过净化系统把杂质除去,以保证燃气发电设备的正常运行;三是燃气发电,利用燃气轮机或燃气内燃机进行发电,有…     

生物质气化过程燃气净化技术研究进展

生物质燃气必须经过净化后才能进行使用。文章针对生物质气化过程中燃气净化效率低、焦油脱除困难等问题,对不同种类燃气净化设备（机械式、过滤式、洗涤式和静电式）的优缺点进行了对比研究,并对利用多级设备联合净化燃气的技术措施和方法进行了分析,深入探讨了生物质燃气在净化过程中面临的问题。同时,基于我国农村小型生物质气化站低成本、低能耗、高效率的要求进行考虑,指出开发高效低廉的适用于农村小型生物质气化站的多级燃气净化系统是促进生物质气化集中供气推广的关键技术。     

生物质焦油裂解的技术关键

生物质焦油是生物质气化过程中有害的副产物，它会降低气化效率，影响设备运行，所以必须加以有效利用和处理。本文介绍了国内外焦油催化裂解的研究现状，详细地分析了讨论了催化裂解的关键过程和工艺件，总结出了焦油催化裂解的最佳条件和比较有前景的工艺路线。     

1MW木粉气化发电系统的运行特性分析

通过对海南三亚木粉发电系统的运行状况分析，结果发现：气化过程中所夹带的飞灰以及所生成的焦油是影响发电系统正常运行的主要因素，显热损失和飞灰中没有完全气化的碳损失是导致气化发电系统效率下降的主要原因。同时考查了气化过程中污染物排放情况及添加焦油裂解催化剂对气体成份和焦油裂解的影响，对改进今后生物质气化发电系统的大型化设计具有一定的指导意义。     

生物质气化发电过程建模与优化

目前国内外在生物质气化发电技术方面,由于缺乏对生物质气化过程特性的建模和参数优化问题的研究,使得生物质燃气中焦油量和污染物的含量过高,燃气品质难以保证,进而对燃气轮机发电机组产生不利的影响,降低了气化燃气的利用价值。因此,对于生物质发电气化过程的建模和重要参数优化控制的研究和探讨具有重要的意义。     

生物质热解气化气中焦油生成机理及其脱除研究

生物质气化气中焦油含量高成为制约生物质气化技术商业化发展的决定性因素之一。在对生物质热解气化过程中焦油的生成及其影响因素进行分析的基础上,采取优化炉内结构与炉外气体湿式净化相结合的方法来脱除气体中的焦油,研究开发出气化剂由侧向送入的气化反应炉,以及相应的集喷淋、水浴、水膜、冲激于一体的湿式净化装置。该生物质气化机组所得到的可燃气具有燃气热值高、焦油含量低、操作简单、安全可靠的特点。气化效率可达到 78％,燃气低位热值为 5.4 MJ/m3(玉米秸 ),焦油含量 48 mg/m3, O2含量为 0.7％,主要技术指标均低于有关行业标准。     

生物质焦油的特性及其净化研究现状

通过分析生物质热解气化过程中焦油的特性和生成机制,以及净化方法研究现状,了解焦油的主要组成和基本特性参数,发现焦油随着反应温度的升高,逐步经过裂解、聚合、缩合反应生成多环芳香烃。而焦油的脱除应当根据不同的生物质气化反应特性,多种方法结合,以减少催化剂损失、提高焦油脱除率和转化率。     

生物质气化气中焦油非催化裂解实验研究

生物质气化是一种环境友好的新能源利用技术,焦油作为生物质气化的副产物,是限制气化技术发展的主要因素.试验针对生物质气化产出气中焦油在700～1 000℃裂解温度区间的裂解特性进行了分析,并提出了焦油裂解产气率的概念.试验表明,焦油裂解气可以成为生物质气化气的有效的能量补充,而且随着裂解温度的升高,焦油裂解产气率增加,焦...     

4MW级生物质气化发电示范工程的设计研究

介绍了我国4MW级的生物质气化整体联合循环发电示范工程的设计特点。该工艺中使用了中温静电除尘、焦油裂解装置和显热回收系统，预计投运后，将会使生物质的气化效率提高、可燃气中焦油含量减少以及系统效率得以提高，为我国生物质能的开发与运用开辟了广阔的前景。     

生物质加压气化技术的研究与应用现状

生物质气化气可以替代化石燃料用于发电、供热和用于生产合成反应的化工原料,解决日益严重的能源短缺和环境污染等问题.加压气化具有生产能力大、效率高,可降低单位投资成本,减少焦油的产生,有利于后续发电及合成工艺等诸多优点.文章介绍了压力对气化的影响,加压气化存在的主要问题,加压在生物质和劣质煤等联合气化、定向气化制备合成气、IGCC上应用的研究和应用现状.     

连续蓄热式生物质气化/燃烧供热系统

生物质能源是一种环境友好的可再生能源,但也存在能量密度低、含水率高、碱金属含量高等缺点,导致其在热利用的过程中存在易结渣、堵灰及腐蚀、热效率不高等问题。本文结合生物质气化、炉内碱金属/硫固定、两级焦油裂解、蓄热式燃烧,以及冷凝热回收等多项先进技术,设计并搭建了连续蓄热式生物质气化/燃烧供热系统。以海洋贝壳类废弃物作为生物质成型燃料的添加剂和生物质焦油裂解过程的催化剂,在实现海洋废弃资源高值化利用的同时,克服了生物质热利用过程中的多项障碍,能够显著提高生物质能热利用效率,同时大幅度降低当前工业及民用供热过程中CO₂、SO_x、NO_x及烟尘的排放,具有良好的经济性与环保性。     

Effect of design and operating parameters on the gasification process of biomass in a downdraft fixed bed: An experimental study

The main objective of this paper is to study the effect of design and operating parameters, mainly reactor geometry, equivalence ratio and biomass feeding rate, on the performance of the gasification process of biomass in a three air stage continuous fixed bed downdraft reactor. The gasification of corn straw was carried out in the gasifier under atmospheric pressure, using air as gasifying agent. The results demonstrated that due to the three stage of air supply, a high and uniform temperature was achieved in the oxidation and reduction zones for better tar cracking. The designing of both the air supply system and rotating grate avoided bridging and channeling. The gas composition and tar yield were affected by the parameters including equivalence ratio (ER) and biomass feeding rate. When biomass feeding rate was 7.5 kg/h and ER was 0.25–0.27, the product gas of the gasifier attained a good condition with lower heating value (LHV) about 5400 kJ/m³ and cold gas efficiency about 65%. An increase in equivalence ratio led to higher temperature which in turn resulted in lower tar yield which was only 0.52 g/Nm³ at ER = 0.32. Increasing biomass feeding rate led to higher biomass consumption rate and process temperature. However, excessively high feeding rate was unbeneficial for biomass gasification cracking and reforming reactions, which led to a decrease in H₂ and CO concentrations and an increase in tar yield. When ER was 0.27, with an increase of biomass feeding rate from 5.8 kg/h to 9.3 kg/h, the lower heating value decreased from 5455.5 kJ/Nm³ to 5253.2 kJ/Nm³ and tar yield increased from 0.82 g/Nm³ to 2.78 g/Nm³.     

Biomass gasification integrated with pyrolysis in a circulating fluidised bed

The use of biomass for energy generation is getting increasing attention. At present, gasification of biomass is taken as a popular technical route to produce fuel gas for application in boilers, engine, gas turbine or fuel cell. Up to now, most of researchers have focused their attentions only on fixed-bed gasification and fluidised bed gasification under air-blown conditions. In that case, the producer gas is contaminated by high tar contents and particles which could lead to the corrosion and wear of blades of turbine. Furthermore, both the technologies, particularly fixed bed gasification, are not flexible for using multiple biomass-fuel types and also not feasible economically and environmentally for large scale application up to 10–50 MW_th. An innovative circulating fluidised bed concept has been considered in our laboratory for biomass gasification thereby overcoming these challenges. The concept combines and integrates partial oxidation, fast pyrolysis (with an instantaneous drying), gasification, and tar cracking, as well as a shift reaction, with the purpose of producing a high quality of gas, in terms of low tar level and particulates carried out in the producer gas, and overall emissions reduction associated with the combustion of producer gas. This paper describes our innovative concept and presents some experimental results. The results indicate that the gas yield can be above 1.83 N m³/kg and the fluctuation of the gas yield during the period of operation is 3.3% at temperature of 750 °C. Generally speaking, the results achieved support our concept as a promising alternative to gasify biomass for the generation of electricity.     

An experimental study on air gasification of biomass micron fuel (BMF) in a cyclone gasifier

Biomass micron fuel (BMF) produced from feedstock (energy crops, agricultural wastes, forestry residues and so on) through an efficient crushing process is a kind of powdery biomass fuel with particle size of less than 250 μm. Based on the properties of BMF, a cyclone gasifier concept has been considered in our laboratory for biomass gasification. The concept combines and integrates partial oxidation, fast pyrolysis, gasification, and tar cracking, as well as a shift reaction, with the purpose of producing a high quality of gas. In this paper, characteristics of BMF air gasification were studied in the gasifier. Without outer heat energy input, the whole process is supplied with energy produced by partial combustion of BMF in the gasifier using a hypostoichiometric amount of air. The effects of equivalence ratio (ER) and biomass particle size on gasification temperature, gas composition, gas yield, low-heating value (LHV), carbon conversion and gasification efficiency were studied. The results showed that higher ER led to higher gasification temperature and contributed to high H₂-content, but too high ER lowered fuel gas content and degraded fuel gas quality. A smaller particle was more favorable for higher gas yield, LHV, carbon conversion and gasification efficiency. And the BMF air gasification in the cyclone gasifier with the energy self-sufficiency is reliable.     

流光电晕放电净化粗燃气焦油及粉尘研究进展

研究焦油及粉尘的高效净化方法对推动生物质气化技术的发展具有重要意义。流光电晕放电过程产生的O、H、OH等活性自由基可有效裂解燃气中的焦油类有机物分子,在直流基压上叠加窄脉冲电压则可实现粉尘的荷电及高效气-固分离,是一种较有应用前景的粗燃气净化方法。笔者对流光电晕放电净化粗燃气焦油及粉尘的技术进展进行了综述,分析了该过程的裂解焦油/除尘机理、研究现状及关键科学问题,并提出了一种基于电旋风等离子体反应器的焦油及粉尘同时净化方法。最后针对生物质气化粗燃气净化过程中的瓶颈问题,简要归纳了其研究重点。