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1.
流化床作为生物质气化反应器试验研究 总被引:13,自引:1,他引:13
在流化床生物质气化炉内 ,用空气进行气化生物质 (花生壳 )的试验研究 ,分析的参数是当量比ER 0 .2— 0 .4 5 ,气化床的温度 75 0— 85 0℃和加入二次风。当ER在 0 .2 5— 0 .33,气化燃气热值为 6 .2— 6 .8MJ/m3 ,气体产量在 2 6 0— 390m3 /h ,生物质燃烧时比气化产量在 1.2 8— 2 .0 3m3 /kg之间 ,炭转化率在 5 3%— 80 %。并对 7种农、林废弃物进行了初步气化试验研究 ,生成的燃气体积分数 :CO为 14 %— 18% ,H2 一般低于 6 % ,甲烷 4 %— 12 %。燃气热值在 4 70 0— 710 0kJ/m3 。试验结果表明 ,在流化床生物质气化炉中 ,通过在悬浮空间加入二次风 ,可使燃气热值得到提高。 相似文献
2.
Among the options for clean energy production, the gasification process is receiving increasing attention as it offers the best combination of investment and value of produced electricity compared to other methods. An Aspen Plus model of co‐gasification of biomass and coal with in situ CO2 capture was developed to evaluate its potential for hydrogen production and cracking of organic impurities, i.e., tars. The effects of some critical operational variables on gas composition and yields of hydrogen gas and tar were investigated. The obtained results indicate that the fuel particle size plays a minor role in the process; smaller particles favor the conversion of tar and production of more hydrogen gas. 相似文献
3.
Andy Gradel Robert Honke Joachim Alfred Wünning Tobias Plessing Andreas Jess 《化学工程与技术》2019,42(9):1895-1906
Thermal gasification of biomass is known for its capabilities in flexible and decentral power station applications for cogeneration. However, the product gas contains tar compounds adversely for a stable operation. Integrated tar adsorption in a subsequent cooled section is therefore an option to reduce the tar pollution. The char coal, used here as adsorption agent, is formed by biomass pyrolysis in the gasifier. A kinetic model is proposed, considering the kinetics of all main reactions as well as heat and mass transport phenomena. Results are presented for axial temperature profiles, gas compositions, and the gas purity at different air‐to‐fuel ratios. The resulting output mass flows could indicate a requirement on the adsorption capacity of at least 0.3 g g?1 for the activated char coal. 相似文献
4.
基于多相流体质点网格方法(MP-PIC)对高灰煤在三维鼓泡流化床气化过程进行了数值模拟研究。在欧拉-拉格朗日框架下将气相和固相分别视作连续介质和离散相处理。首先,将模拟得到的出口处气体组分结果与实验数据进行对比,实验数据与模拟结果具有良好的一致性。其次,研究了煤颗粒在气化炉内的温度、传热系数、速度和停留时间,从颗粒尺度揭示了鼓泡流化床气化炉内的颗粒分布特性和气固流动特征。结果表明:在气化炉入口附近煤颗粒与床层温差最大,传热系数最大;由于流化床内强非线性的气固流动,床中煤温度和传热系数的空间分布不均匀;煤颗粒和床料的瞬时速度具有稳定的波动幅度,其中垂直方向速度波动最明显,且煤颗粒的瞬时速度比床料的瞬时速度略大;由于颗粒间的剧烈碰撞,延长了煤颗粒停留时间。此外,对鼓泡流化床中煤气化过程颗粒尺度的研究,有助于深入了解固体颗粒的流动行为以及气固相相互作用特性,对鼓泡流化床反应器的设计优化具有重要意义。 相似文献
5.
为进一步研究双流化床生物质气化器中合成气含量分布,将气化器鼓泡床层分为气泡相和乳化相,依据动力学反应分别进行各相质量和热量衡算,计算结果与实验值吻合较好. 随气化温度升高,CO含量增加,而H2和CO2含量降低;蒸汽与生物质质量比(S/B)增加促进水蒸汽变换和重整反应,消耗CO和CH4,生成H2和CO2,当S/B从0变化到1.2时,CO/H2变化44%,说明S/B增加主要促进了水蒸汽变换反应. 气化温度870℃及S/B=0.75条件下,当气化器高度为0~0.5 m时,H2O含量急剧下降,H2含量急剧上升,CO与CO2含量逐渐上升,当该高度大于0.5 m后,气化反应基本完成. 相似文献
6.
Methane decomposition is a promising method to obtain COx‐free hydrogen. The main difficulty of this process is that the produced carbon would deposit on the active phase of the catalyst, leading to catalyst deactivation. In this study, a core‐shell‐structured composite catalyst comprising highly active Ni nanoparticles (NP) as core and mesoporous silica as shell is introduced. The silica shells were synthesized by using cetyltrimethylammonium bromide as template and tetraethyl orthosilicate as precursor. Ni NP and Ni@SiO2 were examined as catalysts for hydrogen production by methane decomposition at different temperatures and gas hourly space velocities. The results show that the core‐shell catalyst exhibited much better stability in methane decomposition than Ni NP without silica shell and a traditional supported catalyst. 相似文献
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8.
A nickel-based catalytic filter material for the use in integrated high temperature removal of tars and particles from biomass gasification gas was tested in a broad range of parameters allowing the identification of the operational region of such a filter. Small-scale porous alumina filter discs, loaded with approximately 2.5 wt% Al2O3, 1.0 wt% Ni and 0.5 wt% MgO were tested with a particle free synthetic gasification gas with 50 vol% N2, 12 vol% CO, 10 vol% H2, 11 vol% CO2, 12 vol% H2O, 5 vol% CH4 and 0–200 ppm H2S, and the selected model tar compounds: naphthalene and benzene. At a typical face velocity of 2.5 cm/s, in the presence of H2S and at 900 °C, the conversion of naphthalene is almost complete and a 1000-fold reduction in tar content is obtained. Technically, it would be better to run the filter close to the exit temperature of the gasifier around 800–850 °C. At 850 °C, conversions of 99.0% could be achieved in typical conditions, but as expected, only 77% reduction in tars was achieved at 800 °C.
Conversion data can be reasonably well described with first order kinetics and a dominant adsorption inhibition of the Ni sites by H2S. The apparent activation energies obtained are similar to those reported by other investigators: 177 kJ/mol for benzene and 92 kJ/mol for naphthalene. The estimated heat of adsorption of H2S is 71 kJ/mol in the benzene experiments and 182 kJ/mol in the naphthalene experiments, which points at very strong adsorption of H2S. Good operation of the present material can hence only be guaranteed at temperatures above 830 °C mainly due to the strong deactivation by H2S at lower temperatures. 相似文献
9.
物质气化技术已在国内外得到广泛的开发和运用,但由于燃气品位较差,焦油较多,限制了生物质气化气的进一步利用.近年来生物质的低温气化催化裂解已引起了国内外的广泛关注.分析了目前使用的各种催化剂对减少生物质气化焦油的生成和改进燃料气品质的作用结果,提出了进一步的研究方向. 相似文献
10.
Abrar Inayat Mohsin Raza Zakir Khan Chaouki Ghenai Muhammad Aslam Muhammad Shahbaz Muhammad Ayoub 《化学工程与技术》2020,43(4):649-660
Hydrogen production from biomass steam gasification is systematically reviewed. Equilibrium modeling and simulation studies using various techniques for effective hydrogen production are presented. Heat integration, economic analysis of the hydrogen production, and systematic design algorithms research publications are overviewed and discussed for energy-efficient and economic hydrogen production from various biomass feedstocks. Comparison and analysis of the results strongly suggest the viable potential of biomass steam gasification for hydrogen production from small to large scales with applications for thermal heat, power generation, and many other industrial fields. 相似文献
11.
循环流化床技术在煤气化过程中的应用前景 总被引:7,自引:0,他引:7
循环流化床技术20余年来已成功地应用于许多领域。本文结合煤气化过程原理和循环流化床反应器开发应用状况,分析了该技术用于煤炭气化过程所具有的优势及存在的问题,探讨了循环流化床技术在洁净煤气化方面的应用前景 相似文献
12.
在内耐火衬式流化床中,采用负载不同碱金属及配比催化剂的煤粉为原料,研究了煤粉催化气化过程,探索了自热方式为催化气化过程提供足够反应热的可能性,获得了维持煤气化装置连续稳定运行的工艺条件。经实验研究发现,通过燃煤自供热可为催化气化过程提供所需的能量,并维持炉温在所需温度范围;添加碱金属催化剂后,煤粉对应的着火温度有明显降低,且钾盐对煤粉着火点影响比钠盐显著。同时,催化剂负载量存在一个最佳值;添加催化剂后,维持系统稳定操作的温度范围降低了100~200℃,控制炉温在低于该温度范围内操作,可有效减少结渣;负载催化剂后在较低的气化温度下可实现较高的碳转化率和气化效率,实现装置的连续稳定运行。燃煤自供热的流化床催化气化装置的构建及开发,将解决现有催化气化技术经济性不佳及工程放大难的问题。 相似文献
13.
This article deals with investigation and modeling of batch drying process of solids in fluidized bed apparatus. There has been used model of fluidized bed drying, which consists two zones: emulsion zone and bubbling zone with taking into consideration the presence of solid particles in the bubbles. The results of theoretical expectations that arise from simulation calculations have been verified with experimental data obtained with the use of fluidized bed dryer 0.225 m in diameter. A drying process of silica gel, sand, and ammonium sulfate has been tested. To verify the model, the concept of a generalized drying curve has also been employed. 相似文献
14.
Aspen Plus has become one of the most common process simulation tools for both academia and industrial applications. In the last decade, the number of the papers on Aspen Plus modeling of biomass gasification has significantly increased. This review focuses on recent developments and studies on modeling biomass gasification in Aspen Plus including key aspects such as tar formation and model validation. Accordingly, challenges in modeling due to specific assumptions and limitations will be highlighted to provide a useful basis for researchers and end-users for further process modeling of biomass gasification in Aspen Plus. 相似文献
15.
Cristina P. B. Quitete Vitor L. Ximenes Andrew M. Steele Mariana M. V. M. Souza 《化学工程与技术》2019,42(5):980-986
Biomass gasification experiments on pilot/demo scales have some issues related to the early deactivation of catalysts during the tar removal step. To avoid this problem, a method was developed in a bench‐scale micro activity unit using toluene as tar model compound in order to suppress this effect. The runs were performed with a commercial Pt catalyst supported on Ce‐Zr‐Al, alternating periods of regeneration and reactivation steps with steam, nitrogen, and hydrogen. The toluene steam reforming using operational cycles in order to reach a long‐term run provided useful information for pilot plant studies, mainly reactivation and regeneration procedures. The main concern on tar removal studies by steam reforming is the catalyst deactivation due to the presence of polyaromatic and olefinic compounds on the material pores, which is produced during biomass gasification. 相似文献
16.
L.P.L.M. Rabou 《Fuel》2005,84(5):577-581
Conversion of biomass into producer gas by thermal gasification broadens the scope of biomass applications. Usually, tar has to be removed from the producer gas. Tar recycling within the gasification process may solve the associated waste problem and increase the system efficiency, provided tar is broken down under gasification conditions. We present results of tar recycling experiments at a Circulating Fluidised Bed gasifier. At 830 °C, from each of 15 main tar compounds 70-80% are broken down. Continuous recycling of tar would increase the tar content in raw producer gas by 50% at most and save about 3% fuel input. 相似文献
17.
Tube erosion in a bubbling fluidized bed is numerically studied using the Eulerian‐Eulerian method coupled with a monolayer kinetic energy dissipation model. The hydrodynamical simulations are performed under conditions with three different superficial gas velocities. The time‐averaged bubble frequency and bubble rise velocity are calculated to characterize the bed hydrodynamics. The erosion rates of two target tubes are simulated and the influence of the bubble behaviors on erosion rates is evaluated. Compared with the experimental data in the literature, the bubble behaviors are well captured by the simulations. Good agreement between the calculated and measured erosion rates is also obtained for the two target tubes. The bubble behaviors around the tubes have direct impact on the tube erosion. Only small discrepancies in the calculated erosion rates are found when using different particle‐wall restitution coefficients and specularity coefficients. 相似文献
18.
Catalytic steam reforming of bio‐oil is an economically‐feasible route which produces renewable hydrogen. The Ni/MgO‐La2O3‐Al2O3 catalyst was prepared with Ni as active agent, Al2O3 as support, and MgO and La2O3 as promoters. The experiments were conducted in fixed bed and fluidized bed reactors, respectively. Temperature, steam‐to‐carbon mole ratio (S/C), and liquid hourly space velocity (LHSV) were investigated with hydrogen yield as index. For the fluidized bed reactor, maximum hydrogen yield was obtained under temperatures 700–800 °C, S/C 15–20, LHSV 0.5–1.0 h–1, and the maximum H2 yield was 75.88 %. The carbon deposition content obtained from the fluidized bed was lower than that from the fixed bed. The maximum H2 yield obtained in the fluidized bed was 7 % higher than that of the fixed bed. The carbon deposition contents obtained from the fluidized bed was lower than that of the fixed bed at the same reaction temperature. 相似文献
19.
采用离散颗粒数值模型探讨了气固流化床内多个气泡的运动规律. 数值计算考虑了颗粒与气体的相互作用以及颗粒间的相互作用,颗粒与气体的相互作用采用Gidaspow阻力修正公式,颗粒间的相互作用则采用硬球碰撞模式描述. 给出了一种在二维非结构网格下精确计算颗粒体积分数及两相全隐耦合求解颗粒速度的方法,同时,在硬球模型中对颗粒碰撞事件采用散列表的处理方法,大大提高了计算效率. 数值计算结果表明,由于多个气泡的相互作用而导致气泡的横向运动显著,气泡运动轨迹与气泡形状依赖于流化床内静压力的分布,气泡总是选择压力小、压差梯度大的路径上升,这一现象与气液分离流中气泡的运动规律类似. 相似文献