共查询到19条相似文献,搜索用时 93 毫秒
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生物质型煤是将煤炭与农林废弃物等可燃生物质及添加剂按一定比例混合压制而成的一种固体成型燃料,是煤炭资源的一种洁净利用方式。生物质型煤技术将中国有限的煤炭资源和农村大量的可再生秸秆林木废弃物结合起来,不仅可以实现煤炭尤其是低阶煤的高效清洁利用,而且可以实现农林废弃生物质的资源化和能源化利用。从发展生质型煤的意义、生物质型煤成型的工艺、黏结剂的选用、燃烧机理以及燃烧特性作了综合叙述,并对生物质型煤发展前景进行了展望。发展生物质型煤,对减小大气污染、改善生活环境、缓解国家能源安全危机和实现中国化石能源与可再生能源的合理利用具有重要的战略意义。 相似文献
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以被称为"十大害草"之一的水葫芦为生物质资源,与福建低活性无烟煤混合制备成生物质型煤.在内径为28 mm小型固定床气化反应器中对生物质型煤气化行为进行了实验测定.通过对3组不同生物质配比的型煤分别进行不同时间的气化,考察了生物质型煤气化行为演变过程行为.结果显示,型煤在气化过程中形成较为明显的灰层与未反应的芯层界面,且随着生物质配比的增加,灰层迁移速度较快,气化时间缩短,表明添加生物质有利于提高福建生物质型煤的气化活性. 相似文献
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为解决生物质刚性造成生物质型煤膨胀开裂的难题,利用微生物发酵技术处理生物质秸秆,将发酵改性后的生物质作为添加剂与粉煤按一定比例掺混,冷压成型制得生物质型煤。分析了生物质发酵改性前后形态、结构、发热量的变化,研究了发酵改性生物质对型煤强度、热稳定性的影响,确定生物质型煤最佳配比。结果表明:发酵改性后生物质质地密实,膨胀压缩性能得到改善,活化后大粒径为互相缠绕、团聚的丝状物,小粒径铺展效果较好,且具有包覆性;发酵使秸秆组织变得疏松,秸秆茎特有的2230 cm-1红外峰值消失,有利于煤粒与生物质结合,避免了生物质具有刚性造成型煤膨胀开裂;改性前后发热量变化较小,为0.07 k J/g。生物质型煤最佳配比为:煤炭80%,发酵生物质15%,膨润土5%;制得型煤的抗压强度达到1.4 MPa,落下强度高达98.65%,热稳定性达88.4%,工业分析符合DB 13/1055—2009《洁净型煤》要求。 相似文献
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用CMC作为生物质型煤粘结剂与黄泥生物质型煤进行比较试验表明 ,CMC生物质型煤在防水性 ,防振性能 ,抗压性方面远远优于黄泥生物质型煤 ,燃烧强度相差不明显 ,固硫效率有所提高 ,且可以大大降低粉尘污染。CMC是一种清洁、有效的型煤粘结剂 相似文献
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Jianjun Dai Shahab Sokhansanj John R. Grace Xiaotao Bi C. Jim Lim Staffan Melin 《加拿大化工杂志》2008,86(3):367-386
Low heating values, variable chemical compositions, peculiar physical properties, high investment cost and insecurity of biomass feedstocks supply limit the applications of biomass for energy and other processes. Co‐firing biomass and coal has potential for the development of biomass‐to‐energy capacity with significant economic, environmental, and social benefits. However, co‐firing is not straightforward, and some questions need to be addressed due to the differences in chemical compositions and physical properties of biomass and coal. This paper highlights key issues related to co‐firing, including reactor types, feeding, hydrodynamics, ash sintering, fouling, and corrosion, based on previous studies, as well as calculations and analysis. Direct co‐firing is the most common option for biomass and coal co‐firing currently, mostly due to relatively low investment needed to turn existing coal power plants into co‐firing plants. For direct co‐firing, the physical characteristics and chemical compositions of the fuel entering the combustors or gasifiers are critical to an optimum operation. Any biomass mixed with coal needs to have acceptable physical properties. More research is needed on co‐firing biomass and coal, including work on: preparation, handling, storage, and feeding of biomass feedstocks (e.g. drying, torrefaction, pelletization); co‐firing mechanisms; hydrodynamic analysis of co‐firing combustors and gasifiers; boiler/gasifier capacity, slagging, fouling, corrosion, efficiency, reliability, fuel flexibility; lower emissions and gas cleaning; catalyst poisoning; investment and operating costs. 相似文献
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Marek Pronobis 《Fuel》2006,85(4):474-480
The paper presents an attempt to evaluate the influence of biomass co-combustion on the fouling of boiler convection surfaces. In order to show the influence of co-firing biomass with bituminous coal on boiler efficiency, the calculations of pulverized fuel (PF) OP 140 steam generator have been carried out. Typical Upper Silesian coal with medium fouling inclination has been chosen as a basic fuel. Three kinds of biomass have been taken into consideration: straw, wood and dried sewage sludge. The results confirm that the properties of additional fuels cause deterioration of the boiler efficiency as well as the changes in boilers operational parameters (amount of water injected in attemperators, ash stream, hot air temperature). The biomass during cofiring in fact replaces the coal, but always the additional fuel consumption is higher than that of the substituted coal. Therefore, the actual decrease of coal consumption is smaller than the thermal fraction of the biomass. 相似文献
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A. L. Lapidus 《Solid Fuel Chemistry》2013,47(6):315-328
Basic process for manufacturing liquid fuel and valuable chemicals from nonpetroleum feedstock (coal, natural gas, biomass) is the synthesis of hydrocarbons from CO and H2 on catalysts containing Group VIII transition metals. There are also other processes for producing hydrocarbon mixtures from nonpetroleum feedstock (for example, coal or biomass hydrogenation, coal devolatilization and pyrolysis), but the preferential development of the Fischer-Tropsch process confirms its viability and prospects, which are determined by a huge source of raw materials—coal reserves in the energy equivalent are an order of magnitude higher than those of crude oil. 相似文献
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Using sustainably-grown biomass as the sole fuel, or co-fired with coal, is an effective way of reducing the net CO2 emissions from a combustion power plant. There may be a reduction in efficiency from the use of biomass, mainly as a result of its relatively high moisture content, and the system economics may also be adversely affected.The economic cost of reducing CO2 emissions through the replacement of coal with biomass can be identified by analysing the system when fuelled solely by biomass, solely by coal and when a coal-biomass mixture is used.The technical feasibility of burning biomass or certain wastes with pulverised coal in utility boilers has been well established. Cofiring had also been found to have little effect on efficiency or flame stability, and pilot plant studies had shown that cofiring could reduce NOx and SOx emissions.Several technologies could be applied to the co-combustion of biomass or waste and coal. The assessment studies here examine the potential for co-combustion of (a) a 600 MWe pulverised fuel (PF) power plant, (i) cofiring coal with straw and sewage sludge and (ii) using straw derived fuel gas as return fuel; (b) a 350 MWe pressurised fluidised bed combustion (PFBC) system cofiring coal with sewage sludge; (c) 250 and 125 MWe circulating fluidised bed combustion (CFBC) plants cofiring coal with straw and sewage sludge; (d) 25 MWe CFBC systems cofiring low and high sulphur content coal with straw, wood and woody matter pressed from olive stones (WPOS); and (e) 12 MWe CFBC cofiring low and high sulphur content coal with straw.The technical, environmental and economic analysis of such technologies, using the ECLIPSE suite of process simulation software, is the subject of this study. System efficiencies for generating electricity are evaluated and compared for the different technologies and system scales. The capital costs of systems are estimated for coal-firing and also any additional costs introduced when biomass is used. The Break-even electricity selling price is calculated for each technology, taking into account the system scale and fuel used.Since net CO2 emissions are reduced when biomass is used, the effect of the use of biomass on the electricity selling price can be found and the premium required for emissions reduction assessed. Consideration is also given to the level of subvention required, either as a Carbon dioxide Credit or as a Renewable Credit, to make the systems using biomass competitive with those fuelled only with coal.It would appear that a Renewable Credit (RC) is a more transparent and cost-effective mechanism to support the use of biomass in such power plants than a Carbon dioxide Credit (CC). 相似文献
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Behdad Moghtaderi 《Fuel》2007,86(15):2431-2438
The char burnout characteristics of coal/biomass blends under conditions pertinent to pulverised fuel combustors were investigated by a combined modelling and experimental approach. Results indicate that blending of coal with biomass increases the likelihood of char extinction (i.e. extinction potential of the char particle in the blend), in turn, decreasing the char burnout level. Our modelling results attribute this to a reduction in the char particle size to levels below a critical dimension which appears to be a strong function of the fuel blending ratio (the weight percentage of biomass in the blend), fuel reactivity, char cloud shape and particle density number. It is demonstrated here that the drop in the char burnout level during co-firing can be effectively resolved when a more reactive secondary coal is added to the blend to minimise its extinction potential. 相似文献
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An experimental study on co-pyrolysis of bituminous coal and biomass was performed in a pressured fluidized bed reactor. The blend ratio of biomass in the mixture was varied between 0 and 100 wt%, and the temperature was over a range of 550–650 °C under 1.0 MPa pressure with different atmospheres. On the basis of the individual pyrolysis behavior of bituminous coal and biomass, the influences of the biomass blending ratio, temperature, pressure and atmosphere on the product distribution were investigated. The results indicated that there existed a synergetic effect in the co-pyrolysis of bituminous coal and biomass in this pressured fluidized bed reactor, especially when the condition of bituminous coal and biomass blend ratio of 70:30(w/w), 600 °C, and 0.3 MPa was applied. The addition of biomass influenced the tar and char yields and gas and tar composition during co-pyrolysis. The tar yields were higher than the calculated values from individual pyrolysis of each fuel, and consequently the char yields were lower.The experimental results showed that the composition of the gaseous products was not in accordance with those of their individual fuel. The improvement of composition in tar also indicated synergistic effect in the co-pyrolysis. 相似文献
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《Fuel Processing Technology》2006,87(4):281-288
Co-firing of coal/biomass blends in the existing coal fired power plants is an attractive option for reducing the greenhouse emissions. However, fuel processing and handling problems associated with coal/biomass blends restrict the widespread application of the co-firing technology. In this study, flow properties of typical Australian coal and biomass as well as their blends were systematically studied. The flow property data obtained from this study provided an insight into the underlying phenomena responsible for some of the problems often encountered in handling of coal/biomass blends. The flow properties of the coal and biomass blends were found to be dependent upon the form of biomass being used. We found that blending coal with sawdust reduced the likelihood of flow stoppage because sawdust particles lowered the bulk strength (cohesive strength) of the mixture from that of coal alone while maintaining more or less the same frictional properties as the parent coal. On the contrary, blends of coal and woodchip exhibited frictional characteristics far greater than the parent coal while showing bulk strengths similar to coal. As such, blends of woodchips and coal were found to be more susceptive to flow stoppage. 相似文献