共查询到17条相似文献,搜索用时 281 毫秒
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分析了甘蔗渣的水蒸气气化过程,基于气化过程的物料平衡和化学平衡关系,建立了一种生物质气化过程的数学模型。用该模型模拟计算甘蔗渣在水蒸气氛围下气化后的气体成分,计算结果与试验数据基本相符,尤其在温度950℃之后,计算值和测量值更接近。以甘蔗渣和木薯渣为例,研究该气化模型的特性。甘蔗渣和木薯渣水蒸气气化的最佳水蒸气/燃料值(S/B)分别为0.3和0.2。气化气组分和气化效果随温度和S/B变化的结果表明:提高温度有利于气化反应的进行,提高S/B,可以增加气体产率,气体热值有所降低。 相似文献
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建立了基于热力学平衡的生物质气化模型,利用平衡模型分析了气化过程的特性,研究了气化过程的反应规律及各种因素对气化性能指标的影响,详细分析了当量比及物料湿度对气体产物成分及气化产物热值的影响.同时,建立了以生物质气为燃料的固体氧化物燃料电池的数学模型,该模型考虑了燃料电池的能斯特电动势及各种极化损失.利用建立的模型分析了操作参数以及物料湿度和生物质种类对生物质气化—燃料电池发电系统性能的影响.结果表明,生物质气化—燃料电池发电系统的发电效率可达30%,热电联产效率最高可达95%以上. 相似文献
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建立下吸式生物质气化炉热力学平衡模型,该模型包括焦炭、焦油和气体,并用已公布的实验数据对模型进行验证,均方根(RMS)在1.304~3.814之间,结果表明该模型的预测值与实验数据吻合较好,可认为模型可靠。然后模拟棉秆在下吸式生物质气化炉中以空气和富氧气体2种气化氛围下,不同操作参数(当量比、预热温度和气化炉反应温度)下对棉秆气化的气体组分、热值和产率的影响。模拟结果表明:富氧气体为气化剂时,当量比从0.20增至0.35时,气体中N2含量比空气显著下降,达10%以上,同时发现能提高气体中H2和CO的含量和热值,热值比空气提高约20%。预热温度对气化成分变化影响有限,随预热温度从30 ℃变化到130 ℃,气体的平均热值从空气的5.2 MJ/m3提高到富氧气体的7.0 MJ/m3。随气化炉内反应温度从750 ℃升至1250 ℃,空气和富氧气体2种气化剂下的H2和CO分别从20.94%、26.84%和21.77%、28.67%下降到4.06%、9.12%和10.49%、21.60%,导致气体的热值降低。 相似文献
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对安徽区域内的生物质调研取样并进行工业分析、元素分析和气化特性分析。利用模型对不同生物质气化过程进行模拟计算,得到生物质含水率M_(ad)、气化温度T和气化剂当量比ER对生物质气组分、低位发热量、气化热效率和气化产率的影响。对秸秆类生物质,在气化条件为:M_(ad)0.1,ER=0.24~0.30,T=600℃~750℃下,可获得综合指标较好的生物质气,如当涂水稻秸秆在M_(ad)=0.05,ER=0.25,T=690℃条件下,获得生物质气的综合指标最佳。对水稻、小麦秸秆等生物质气化炉设计和运行具有指导意义。 相似文献
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串行流化床生物质气化制氢试验研究 总被引:2,自引:0,他引:2
基于串行流化床生物质气化技术,以水蒸气为气化剂,在串行流化床试验装置上进行生物质气化制氢的试验研究,考察了气化反应器温度、水蒸气/生物质比率(S/B)对气化气成分、烟气成分和氢产率的影响。结果表明:在燃烧反应器内燃烧烟气不会串混至气化反应器,该气化技术能够稳定连续地从气化反应器获得不含N_2的富氢燃气,氢浓度最高可达71.5%;气化反应器温度是影响制氢过程的重要因素,随着温度的升高,气化气中H_2浓度不断降低,CO浓度显著上升,氢产率有所提高;S/B对气化气成分影响较小,随着S/B的增加,氢产率先升高而后降低,S/B的最优值为1.4。最高氢产率(60.3g H_2/kg biomass)是在气化反应器温度为920℃,S/B为1.4的条件下获得的。 相似文献
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Gasification is a thermo-chemical reaction which converts biomass into fuel gases in a reactor. The efficiency of conversion depends on the effective working of the gasifier. The first step in the conversion process is the selection of a suitable feedstock capable of generating more gaseous fuels. This paper analyses the performance of different biomasses during gasification through energy and exergy analysis. A quasi-equilibrium model is developed to simulate and compare the feasibility of different biomass materials as gasifier feedstock. Parametric studies are conducted to analyze the effect of temperature, steam to biomass ratio and equivalence ratio on energy and exergy efficiencies. Of the biomasses considered, sawdust has the highest energy and exergy efficiencies and lowest irreversibility. At a gasification temperature of 1000 K, the steam to biomass ratio of unity and the equivalence ratio of 0.25, the energy efficiency, exergy efficiency and irreversibility of sawdust are 35.62%, 36.98% and 10.62 MJ/kg, respectively. It is also inferred that the biomass with lower ash content and higher carbon content contributes to maximum energy and exergy efficiencies. 相似文献
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Joel George P. Arun C. Muraleedharan 《International Journal of Hydrogen Energy》2018,43(20):9558-9568
Energy generation from renewable and carbon-neutral biomass is significant in the context of a sustainable energy framework. Hydrogen can be conveniently extracted from biomass through thermo-chemical conversion process of gasification. In the present work, an artificial neural network (ANN) model is developed using MATLAB software for gasification process simulation based on extensive data obtained from experimental investigations. Experimental investigations on air gasification are conducted in a bubbling fluidised bed gasifier with different locally available biomasses at various operating conditions to obtain the producer gas. The developed artificial neural network consists of seven input variables, output layer with four output variables and one hidden layer with fifteen neurons. The multi-layer feed-forward neural network is trained employing Levenberg–Marquardt back-propagation algorithm. Performance of the model appraised using mean squared error and regression analysis shows good agreement between the output and target values with a regression coefficient, R = 0.987 and mean squared error, MSE = 0.71. The developed model is implemented to predict the producer gas composition from selected biomasses within the operating range. This model satisfactorily predicted the effect of operating parameters on producer gas yield, and is thus a useful tool for the simulation and performance assessment of the gasification system. 相似文献
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With the critical worldwide energy shortage and global environment concern, lignocellulosic biomass is regarded as one of the potential renewable energy resources to substitute conventional fossil fuels. Among various thermo-chemical conversion technologies, gasification is now regarded as an advanced and efficient method. Based on the mechanism of biomass gasification, this paper outlines different types of gasifiers that have been developed in China. Air gasification technology has been employed in the rural areas or forestry/agricultural processing entities. Obviously, the product gas for cooking and heating can significantly upgrade the living standard of rural residents. The product gas for heating boiler and generating electricity benefits the forest or agricultural processing enterprises. For China’s sustainable development of energy and environment, multi-cogeneration of heat, electricity and liquid fuels together with chemical feedstock will be a potential direction for efficiently utilizing product gas from lignocellulosic biomass. This means oxygen (including oxygen-enriched air) gasification and steam gasification should be taken into more consideration. 相似文献
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Numerical and experimental investigation of hydrogen-rich syngas production via biomass gasification
Ebubekir Siddik Aydin Ozgun Yucel Hasan Sadikoglu 《International Journal of Hydrogen Energy》2018,43(2):1105-1115
In this work, the relation between hydrogen-rich syngas production and the gasification parameters such as equivalence ratio (ER), gasification temperature and biomass moisture content were studied. Stoichiometric equilibrium model that developed during this study was used to investigate the optimum hydrogen output generated from woody biomass in a fixed bed downdraft gasifier by considering the thermodynamic equilibrium limit. The mathematical model, based on thermodynamic equilibrium is necessary to understand complicated gasification process that will contribute to obtain maximum attainable hydrogen production. The effects of different oxidizing agents on the hydrogen concentration in the product gas as well as the effect of various air-biomass, oxygen-biomass and steam-biomass ratios were investigated. For validation, the results obtained from the mathematical model were compared with the experimental data obtained from the gasifier that uses air as gasification medium. The validated mathematical model was used to represent the gasifier that uses both oxygen and air-steam mixture as the gasification medium and the theoretical results were obtained for both cases. The theoretical results clearly show that the gasification process specially ones that use the air-steam mixture as the gasification medium can be used for hydrogen production. 相似文献
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This investigation concerns the process of air biomass gasification in a fixed bed gasifier. Theoretical equilibrium calculations and experimental investigation of the composition of syngas were carried out and compared with findings of other researchers. The influence of excess air ratio (λ) and parameters of biomass on the composition of syngas were investigated. A theoretical model is proposed, based on the equilibrium and thermodynamic balance of the gasification zone.The experimental investigation was carried out at a setup that consists of a gasifier connected by a pipe with a water boiler fired with coal (50 kWth). Syngas obtained in the gasifier is supplied into the coal firing zone of the boiler, and co-combusted with coal. The moisture content in biomass and excess air ratio of the gasification process are crucial parameters, determining the composition of syngas. Another important parameter is the kind of applied biomass. Despite similar compositions and dimensions of the two investigated feedstocks (wood pellets and oats husk pellets), compositions of syngas obtained in the case of these fuels were different. On the basis of tests it may be stated that oats husk pellets are not a suitable fuel for the purpose of gasification. 相似文献
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《International Journal of Hydrogen Energy》2020,45(46):24263-24274
A drying-autothermal gasification scheme with torrefied biomass as auxiliary feedstock was proposed for the first time in order to realize the decentralized treatment of sewage sludge in wastewater treatment plant. Thermodynamic equilibrium and energy flow balance for the proposed system were evaluated. A non-stoichiometric thermodynamic equilibrium model was applied to evaluate the effect of adding ratio of torrefied biomass on the autothermal gasification performance. A novel dual-check algorithm was developed to determine the molar numbers of syngas components and the injected air. The energy utilization ratio for the whole process was introduced to measure the ratio of the energy used in the whole system to the total input energy. High adding ratio of torrefied biomass was favor of lifting the cold gas efficiency, but it would lead to low energy utilization ratio in terms of sewage sludge treatment. 相似文献
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Two zone equilibrium and kinetic free model proposed by the authors in their earlier work [Ratnadhariya JK, Channiwala SA. Two zone equilibrium and kinetic free modeling of gasifier. Proceedings of the 12th European Conference and Technical Exhibition on Biomass for Energy, Industry and Climate Protection. Amsterdam, The Netherlands; 2002. p. 813–816], offers gas composition, temperature profile and gasifier performance parameters for two zones. This model does not predict composition and temperature profile of pyrolysis zone, which is stated to be a precursor for gasification. Looking to this fact a three zone equilibrium and kinetic free model of biomass gasifier is proposed in the present work. In this three zone: first zone of the model is drying and pyrolysis zone combined together; second zone is oxidation zone; and the third zone is the reduction zone. Each zone has been formulated with: (i) reaction stoichiometry; (ii) constituent balance; and (iii) energy balance along with a few justifying assumptions. This model clearly provides an operating range of equivalence ratio and moisture content for the woody biomass materials. Further, this model facilitates the prediction of the maximum temperature in the oxidation zone of gasifier, which provides useful information for the design of the gasifier and selection of the material for the construction. The merits of the model lies in the fact that it is capable of handling predictions for all category of biomass materials with a wide operating range of equivalence ratio and moisture content in all of the three principal zones of the gasifier. 相似文献