共查询到17条相似文献,搜索用时 171 毫秒
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采用热解、重整、燃烧解耦分离的解耦三床气化(decoupled triple bed gasification,DTBG)系统,以橄榄石为原位焦油裂解催化床料,进行了煤催化气化实验。研究了煤种、煤进料速率、重整器温度以及水碳比(S/C)对煤热解焦油裂解/重整反应的影响。结果显示:随着煤挥发分含量增加,气体产率、碳转化率、冷煤气效率以及产气中的H_2含量增加。由于半焦不参与气化反应,导致碳转化率和冷煤气效率偏低。煤和催化剂比例的改变会影响气体产率和产气组成,当煤的进料速率从0.12 kg/h增加到0.30 kg/h时,气体产率从0.28 m~3/kg增加到0.46 m~3/kg,H_2含量从28.4%增加到50.5%。重整器温度的升高有利于促进煤焦油裂解转化,从而增加气体产率。当重整器温度为850℃、S/C为1.0时,气体产率达到了0.60 m~3/kg,橄榄石催化剂有效地降低了焦油含量,焦油产率仅为2.11g/m~3。S/C的升高增强了焦油水蒸气重整反应,但引入过量的水蒸气会导致反应器内气体的流速加快,缩短了反应物的停留时间和反应时长,减缓了焦油水蒸气重整反应的反应程度。 相似文献
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随着环保要求日趋严格,固定床气化焦油引起的环境问题成为制约固定床气化技术发展的瓶颈,低焦油气化应得到重视。本文介绍了固定床气化中实现低焦油气化的途径及影响因素,分析了各工艺条件对焦油产量的影响,阐述了两段炉、下吸式炉型以及两段供风式气化炉降低焦油的原理。较为普遍的是将下吸式与两段式气化炉相结合,生成的焦油含量低,燃气热量高,炉内热量损失率低,多用于生物质气化技术开发。喉口结构既能增加气速,又能提高炉内温度,促进炉内焦油裂解。气化原料、粒径、气化工艺(气化终温、压力、气化剂、催化剂等)是影响焦油产率的重要因素。高挥发分的气化原料(低阶煤、生物质等)生成的焦油较多,挥发分较低的高阶煤焦油含量很少。粒径影响挥发分析出与传热,从而影响焦油产率。温度的影响主要在于焦油裂解,焦油裂解占裂解反应的主反应时,随温度上升,焦油产率逐渐降低,因此,部分催化剂与后续脱焦油技术需根据温度对焦油的热裂解作用来降低焦油含量。增大压力会抑制挥发分析出,有利于减少焦油。通入适量水蒸气能降低焦油含量,增加氢气含量,但会降低气化温度,需进行定量参数调节。各种催化剂能有效降低焦油含量且改变煤气热值,但催化剂反应条件严格,会增加气化成本。低焦油气化能产生清洁的新能源,是固定床气化技术的重要突破,既能提高低阶煤利用率,又能解决高挥发分的生物质、城市垃圾气化问题。煤气中焦油含量减少,有效气体成分提高,有效缓解低热值气化原料产气热值过低的问题。 相似文献
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在循环流化床锅炉上耦合流化床热解反应器既可提供电力又副产热解油,明显提高煤的利用价值。在这个过程中,热解反应器通常利用自身产生的热解气作为流化介质。本文考察了模拟热解气反应气氛对流化床煤热解拔头制取热解油产率的影响,并利用TG-FTIR分析了焦油官能团组成及随TG温度的变化。针对锅炉用烟煤的实验结果表明:采用热解气作为反应气氛时焦油产率最大,相对无水无灰基煤达13%。反应气氛中H2和CO2的存在不利于焦油生成,但CO 和CH4的加入提高了焦油产率;H2的加入有利于焦油中酚羟基、羧基类化合物生成,同时也促进了脂肪族化合物的裂解;CH4的存在可以提高焦油中单环芳烃、脂肪族及酚羟基类化合物的含量。 相似文献
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在现有生物质气化反应器及焦油处理方法的基础上,开发出一种整体式新型生物质气化催化反应器,并对该反应器进行相关的实验研究。实验研究结果表明:当木粉进料速率为6.48 g/min,空燃比RE为0.23,气化温度在500—670℃,这种整体式新型生物质气化催化反应器内有、无催化剂时对木粉气化产生的燃气中焦油的含量以及气体组分有明显影响;当采用钴与氧化钴的质量分数为20%,氧化钙的质量分数为80%的钴基催化剂作为焦油裂解催化剂,裂解温度为800℃,标态下体积空时为1.8 s的情况下,燃气中夹带的焦油可完全被催化裂解,同时燃气中的气体成分氢体积分数可从无催化剂时的15%提高到有催化剂时的35%,净提高20%。同时也对使用前后的钴基催化剂进行了XRD表征分析,发现氧化钙在生物质气化过程中具有一定的CO2捕集能力。 相似文献
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A poly-generation process of simulated circulating fluidized bed (CFB) combustion combined with coal pyrolysis was developed in a laboratory scale. Pyrolysis characteristics of three bituminous coals with high volatile contents were investigated in a fixed bed with capacity of 10 kg solid samples. The effects of initial temperature of solid heat carrier, pyrolysis holding time, blending (ash/coal) ratio and coal particle size on gas and tar yields were studied experimentally. The results indicate that the initial temperature of the heat carrier is the key factor that affects the gas and tar yield, and the gas composition. Most of the gas and the tar are released during the first few minutes of the pyrolysis holding time. For caking coal, the amount of char agglomerating on the pyrolyzer inner wall is reduced by enhancing the blending ratio. The experimental results may provide basic engineering data or information for the process design of CFB combustion combined with coal pyrolysis in a large scale. 相似文献
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在小型两段式固定床反应器中,对生物质热解气在高温煤焦层中的裂解反应特性进行了研究,重点考察了两段式热解中裂解温度、停留时间及煤焦特性对焦油裂解率、气体产率及成分的影响.结果表明,增加气体停留时间及裂解温度,都有利于促进生物质气中焦油裂解和气体产率提高.裂解温度对气体产率、组分及焦油裂解率影响更明显,高温促进H2和CO的生成,1000℃时H2和CO的含量达到94.51%.当生物质热解气在煤焦中停留时间达到1.41s后,气体中各组分变化趋于缓慢;不同热解条件所制得的煤焦对生物质气中焦油裂解效果不同,较低制焦温度和较短热解时间都有利于增加煤焦的反应活性,促进焦油分解为可燃气体. 相似文献
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Coal topping gasification refers to a process that extracts the volatiles contained in coal into gas and tar rich in chemical structures in advance of gasification. The technology can be implemented in a reactor system coupling a fluidized bed pyrolyzer and a transport bed gasifier in which coal is first pyrolyzed in the fluidized bed before being forwarded into the transport bed for gasification. The present article is devoted to investigating the pyrolysis of lignite and bituminite in a fluidized bed reactor. The results showed that the highest tar yield appeared at 823 to 923 K for both coals. When coal ash from CFB boiler was used as the bed material, obvious decreases in the yields of tar and pyrolysis gas were observed. Pyrolysis in a reaction atmosphere simulating the pyrolysis gas composition of coal resulted in a higher production of tar. Under the conditions of using CFB boiler ash as the bed material and the simulated pyrolysis gas as the reaction atmosphere, the tar yields for pyrolytic topping in a fluidized bed reactor was about 11.4 wt.% for bituminite and 6.5 wt.% for lignite in dry ash-free coal base. 相似文献
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利用煤焦作为催化剂,采用小型石英管固定床为反应装置,对甲烷在煤焦、脱灰煤焦、煤灰以及石英砂床层上在温度为1123 K下的裂解反应进行了较为详细的研究。甲烷在脱灰煤焦上和新鲜的褐煤焦上的转化率和氢气收率有一定的差别。煤灰作为催化剂时,甲烷初始转化率和氢气初始收率分别为9.81%和8.14%。表明煤焦中的灰成分对甲烷裂解有一定的影响。随着反应时间的增加,甲烷的转化率和氢气的收率都逐渐降低。通过扫描电子显微镜和比表面积测定仪对反应前后的褐煤焦、脱灰煤焦进行了表征。甲烷裂解后煤焦比表面积、微孔容都明显降低,平均孔径增大。说明甲烷裂解生成的积炭堵塞煤焦的微孔。SEM照片显示甲烷裂解后积炭覆盖在煤焦的表面,使煤焦的催化活性逐渐降低。 相似文献
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为从高粱秸秆生产高品质、低焦油含量生物合成气,基于其单段热解特性研究,借助两段式固定床反应器实施两段热解(热解+裂解),同时考察页岩灰对热解挥发分的催化裂解效果。结果表明:相对单段热解,两段热解强化了水蒸气与挥发分(尤其是与热解气)的交互;提高裂解温度促进焦油裂解和重整,便利了热解气的生成,同时提高合成气(H2+CO)的产率和H2/CO体积比;裂解中加入页岩灰显著促进生物焦油气化,大幅降低气体产物焦油含量:裂解温度适中(约850℃)时(450℃热解),热解气产率超过40%(质量),焦油产率低于1.0%(质量),合成气产量约186 ml·g-1、体积分数高达64%,且H2/CO比超过0.5。页岩灰便利H2的生成,主要源于其铁组分对水气变换的催化作用。 相似文献
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Pilot Development of Polygeneration Process of Circulating Fluidized Bed Combustion combined with Coal Pyrolysis 总被引:1,自引:0,他引:1
A pilot polygeneration process of a 75 t h–1 circulating fluidized bed (CFB) boiler combined with a moving bed coal pyrolyzer was developed based on laboratory‐scale experimental results. The process operation showed good consistency and integration between boiler and pyrolyzer. Some critical operating parameters such as hot ash split flow from the CFB boiler to the pyrolyzer, mixing of hot ash and coal particles, control of pyrolysis temperature and solid inventory in the pyrolyzer, and pyrolysis gas clean‐up were investigated. Yields of 6.0 wt‐% tar and 8.0 wt‐% gas with a heating value of about 26 MJ m–3 at 600 °C were obtained. Particulate content in tar was restrained less than 4.0 wt‐% by using a granular filter of the moving bed. Operation results showed that this pilot polygeneration process was successfully scaled up. 相似文献