| 改进型气升式硝化反应器剪切特性的研究 |
| 摘要点击 1306 全文点击 931 投稿时间：2005-05-01 修订日期：2005-06-23 |
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| 中文关键词 气升式硝化反应器 剪切率 静态混合器 |
| 英文关键词 airlift nitrifying bioreactor shear rate static mixer |
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| 中文摘要 |
| 研究了气升式硝化反应器的剪切特性及其影响因素.结果表明,该反应器的剪切率呈现一定的空间分布.当进气流量为430～2 700 L·h-1时,反应器总体剪切率为(0.702～3.13)×105s-1,升流区剪切率为(1.07～31.3)×105s-1,气液分离区剪切率为(1.12～25.0)×105s-1,最大剪切率出现在升流区.操作条件和反应器结构对该反应器的剪切率均有重大影响.当进气流量控制在1 300～2 700 L·h-1时,升流区和气液分离区的剪切率先降低后升高.剪切率与导流筒直径呈负相关,导流筒直径从4.0cm增大到5.5cm,升流区、气液分离区及总体剪切率分别降低85.5%、82.3%、80.6%.而与混合元件数成正相关,当导流筒直径为4.0cm时,较之普通反应器,改进型反应器升流区剪切率增大6.14(N=10)和7.97(N=39)倍,气液分离区剪切率增大7.18(N=10)和9.14(N=39)倍,总体剪切率增大6.35(N=10)和8.44(N=39)倍.该反应器的局部最大剪切率与总体剪切率之比(β)为3.68～7.66,采用较大的导流筒尺寸和适宜的静态混合元件数可促进剪切率的均匀分布. |
| 英文摘要 |
| The characteristics of shear rate in an airlift nitrifying bioreactor and its influencing factors were studied.The results showed that the shear rate was different in different sections of the bioreactor.With inlet gas flowrate at 430～(2 700) L·h-1,the overall shear rate was(0.702～3.13)×105 s-1,shear rate in riser was(1.07～31.3)×105 s-1, and in gas-liquid separator was(1.12～25.0)×105 s-1,,respectively.It indicates that the highest shear rates prevailed in the riser part of bioreactor.The operational variables and the bioreactor configurations exerted a significant influence on the shear level of the bioreactor.When inlet gas flowrate was raised from(1 300) to(2 700) L·h-1,,shear rate in riser and separator ascended first and then descended subsequently.The diameter of draft tube(d) was negatively correlated with shear rate.When the draft tube with diameter of 5.5 cm was installed,the shear rates in riser,separator and overall shear rate were 85.5%,82.3% and 80.6%,respectively less as compared with that with diameter of 4.0 cm.The number of static mixers(N) was positively correlated with the shear rate.When d was set at 4.0 cm,with N of 10 and 39,the shear rates in riser were 6.14 and 7.97 times higher respectively,than that of conventional bioreactor.The ratio of maximum local shear rate to overall shear rate was 3.68～7.66,and the homogeneity of the shear field in airlift bioreactors could be improved if d and N were set at 5.5 cm and 10～13,respectively. |
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