连续搅拌槽反应器
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连续搅拌槽反应器(英语:Continuous Stirred-Tank Reactor,简称CSTR),也可以称作全混流反应器,vat-reactor或是backmix reactor,是化学工程中一个常见的化学反应器模型。CSTR通常是指在使用continuous agitated-tank reactor要达到指定出料条件时用来估计关键操作变数的模型[notes 1] 。该数学模型适用于所有流体:液体、气体和浆体。
![](http://images.weserv.nl/?url=//upload.wikimedia.org/wikipedia/commons/thumb/f/f2/Continuous_bach_reactor_CSTR.svg/80px-Continuous_bach_reactor_CSTR.svg.png)
CSTR的行为通常会以连续理想搅拌槽反应器(Continuous Ideally Stirred-Tank Reactor,CISTR)建模,所有由CISTR进行的计算皆已假设其为完美搅拌。在一个完美搅拌的反应器中,出料的组成会与反应器内的组成一致,而组成与滞留时间及反应速率有关。以工程方面来说,一般会假设滞留时间是搅拌时间的5-10倍。CISTR模型通常用于简化工程计算并可用于描述及研究反应器。然而实际上,反应只能接近而无法达到完美状态,特别是在具工业规模的反应器中。
反应模型
假设反应为理想情况(完美搅拌),则在体积为 的反应器内物料 (莫耳数为 )的总质量平衡可表示成:
(累积量=进料-出料+生成)
如果要建立一个非等温或是单一反应的系统时,则必须要考虑额外的控制变数。如果系统被认为处于不稳定状态,那么就必须求解微分方程或是耦合微分方程组。
应用
CSTR通常应用于废水处理过程中。CSTR可以促进稀释速率,使它们能抵抗碱性或酸性的挥发性脂肪酸废弃物。与其他类型的反应器相比,CSTR的效率较低,因为它们需要更大的反应器体积以达到与其他反应器模型(如塞流反应器)相同的反应速率。
参见
备注
- ^ Chemical reactors often have significant heat effects, so it is important to be able to add or remove heat from them. In a CSTR (continuous stirred tank reactor) the heat is added or removed by virtue of the temperature difference between a jacket fluid and the reactor fluid. Often, the heat transfer fluid is pumped through agitation nozzle that circulates the fluid through the jacket at a high velocity. The reactant conversion in a chemical reactor is a function of a residence time or its inverse, the space velocity. For a CSTR, the product concentration can be controlled by manipulating the feed flow rate, which changes the residence time for a constant chemical reactor. Occasionally the term "continuous" is misinterpreted as a modifier for "stirred", as in 'continuously stirred'. This misinterpretation is especially prevalent in the civil engineering literature. As explained in the article,"continuous" means 'continuous-flow' — and hence these devices are sometimes called, in full, continuous-flow stirred-tank reactors (CFSTR's).
参考资料
- ^ 1.0 1.1 Schmidt, Lanny D. The Engineering of Chemical Reactions. New York: Oxford University Press. 1998. ISBN 0-19-510588-5.