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生物油水溶性组分水蒸汽重整制氢研究
其他题名Study on Hydrogen Production by steam reforming of bio-oil aqueous fraction
蔡炽柳
导师闫常峰
2009-05-30
学位授予单位中国科学院广州能源研究所
学位授予地点广州能源研究所
学位名称硕士
关键词生物油 水溶性组分 制氢 白云石 Co2吸收
摘要随着经济的发展和人口的增长,人类对能源的需求越来越大。化石燃料污染性及不可再生的特点使得人类越来越重视新能源的开发。氢能作为一种理想的二次清洁能源日益受到全球的重视和关注,用可再生能源生物质制氢极具有吸引力和发展前途。生物油能量密度相对较大,易于运输和大规模储存,使之成为制氢的理想原料。在生物油制氢过程中加入CO2吸收剂可以打破化学平衡,使反应向着氢气增加的方向移动,增大产气中氢气含量,提高氢产率。本文以白云石煅烧物为吸收剂,在固定床反应器上考察了CO2吸收剂对生物油水溶性组分水蒸汽重整制氢的改善情况,探索温度、吸收剂粒径等参数对制氢反应的影响,结论如下: (1)实验所用白云石的热分解分为两步,在N2气氛中首先在700°C左右分解成CaCO3、MgO和CO2,接着在800°C左右继续分解成CaO、MgO和CO2。在CO2气氛中,分解反应的温度提高,分解最快的温度为870°C。白云石的煅烧产物在CO2气氛下400°C-750°C的温度范围内吸收CO2,处于白云石煅烧产物的增重过程。800°C以后吸收CO2的产物开始分解,一直持续至900°C,之后质量不再发生变化。 (2)生物油水溶性组分水蒸汽重整制氢反应中,实验发现在500~700°C的温度范围内,降低温度有利于提高氢气含量,提高温度有利于提高氢产率,对于本实验来说,600°C是比较理想的重整温度。较大的粒径和较小的粒径条件下获得较高的氢产率,中等粒径条件下氢产率较低。当水油比为4.5时反应获得较高的氢产率75%,较高的水油比会使得大量的水分进入反应区域吸收热量蒸发,降低反应区域的反应温度不利反应进行。再生循环反应的氢气含量变化不大,氢产率也和初始实验基本一致。经过脱硫预处理的吸收剂反应时表现出良好的性能,其氢气含量和氢产率分别为93%、80%,整体上比未经处理的高。 (3)在600°C时添加CaO作为CO2吸收剂后,氢气含量高达86%,氢产率为57%。添加白云石氢产率最高为79%,大于添加CaO和没加添加吸收剂时的氢产率,而氢气含量最高为80%,略低于添加CaO时的86%,这是由于添加白云石时更多焦油向气相产品转化。
其他摘要With the development of economy and the growth of population, the demand for energy has been growing larger and larger. Among those energy resources, fossil fuel is not renewable and causes great pollution. Hydrogen, a form of ideal clean secondary energy has increasingly attracted attention worldwide. Hydrogen production from biomass has been heavily focused on in recently years for the feedstock is renewable. One possible way is to convert biomass into bio-oil, a liquid featuring larger energy density than bio-oil and favorable for transportation and storage, then to be steam reformed to produce hydrogen. As carbon dioxide is produced during the reforming process, the removal of it will result in the shift of the equilibrium to the direction that favors hydrogen production. In this paper, calcined dolomite was used as the carbon dioxide sorbent to enhance the hydrogen production. Experiments were carried out in a laboratory scale fixed-bed and influencing factors like temperature, particle size were investigated. Based on the investigation, following conclusions have been reached: The thermal decomposition of dolomite used in the experiment is divided into two steps, first the dolomite was decomposed into CaCO3、MgO and CO2 in an atmosphere of N2 at 700°C, followed by further decomposition into CaO、MgO at about 800°C. The temperature of decomposition reaction increased in an atmosphere of CO2, which can be illustrated by the fact that decomposition temperature under CO2 atmosphere is 870°C. The product of calcined dolomite begun to absorb CO2 in an atmosphere of CO2 at the range of 400°C-750°C,which was under the gain process of the product of calcined dolomite.The product absorbing CO2 begun to decompose above 800°C,and it did until 900°C,above which its quality never changed. The experiment of catalytic steam reforming bio-oil aqueous fraction led to the following findings: reducing temperature is conducive to improve hydrogen content, and increasing temperature is conducive to improve hydrogen yield in the temperature range of 500~700°C. Large-sized and small-sized particles seem to have better performance in hydrogen production than medium-sized particles. The highest hydrogen yield of 75% was obtained when the steam to bio-oil ratio was 4.5. To further increase the steam to bio-oil ratio seems to have negative effect on hydrogen production. This could be explained by the fact that water was pumped into the reactor to vaporize, which means too much water may lead to the drop in the reaction zone due to its large latent heat. Sorbents were regenerated to perform cycle test. The hydrogen content varied little among different cycles, while the hydrogen yield dropped slightly. Dolomite was pretreated to improve its absorption capability. The hydrogen production after pretreatment showed better performance, with a hydrogen content of 93% and a hydrogen yield of 80% being reached, both of which were larger than that before the pretreatment. The catalytic steam reforming for the case of dolomite shows 83 % hydrogen yield which is much higher than the one of the CaO (56%) and the one without CO2 absoption (42%), and shows 80% hydrogen content which is slightly lower than the one of the CaO (85%), that is come from that more carbonaceous deposit or tar converts into gas product for the dolomite.
页数60
语种中文
文献类型学位论文
条目标识符http://ir.giec.ac.cn/handle/344007/5842
专题中国科学院广州能源研究所
推荐引用方式
GB/T 7714
蔡炽柳. 生物油水溶性组分水蒸汽重整制氢研究[D]. 广州能源研究所. 中国科学院广州能源研究所,2009.
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