There is an equilibrium reaction (Esterification) happening at high temperature of 250 C which is also kinetic controlled. Water is formed as a byproduct in the reaction which has to be removed continuously in order to proceed forward to product side. Currently 60 % water is evaporated in the liquid bulk (70 m^3) inside the reactor. Will mixing or agitation help in removing rest of the water or ~100% water evaporation?
The evaporation of water might be controlled by mass transfer. In this case the agitation decreases water concentration gradients in solution and might increase the interface surface area. If water and product make an azeotrope, the full removal of water is questionable.
You want to see the feed to remove any water, and for process itself to review the methods that are used for water removal. Some of them consume more energy. My guess is agitation can promote heat transfer but it won't make water removal 100% (based on the stated information). Often additional methods are used to remove water residual.
Stirring will speed up evaporation, but whether all water will be removed during reaction time, it is hard to say. In laboratory scale experiments, all water can be removed by a continuous flow of nitrogen, even at temperatures just over 373 K. But here is a completely different scale. I would like to add that in the case of esterification, reactive distillation is often used,
Hello Sir,
Currently in our reactors, there is a practice of recirculating the liquid from bottom and spraying it from top in a continuous nitrogen flow environment. But there is no other agitation (side or bottom) provided in the liquid volume of around 70 m^3(7 m height). So whatever water is generated, 60% are evaporated in the liquid bulk only without agitation while max 20 % is transferred from top circulating liquid.
Yurii V Geletii sir, thanks for the reply.
Water and other liquids do not form azeotrope and water density is higher than others and thus can settle in bottom if not evaporated. The decrease in water concentration gradients might be helpful in higher evaporation.
Mirosław Grzesik sir, Thanks for the reply.
You pointed a very good point of continuous removal of vapor by the use of nitrogen flow which I should have mentioned earlier.
This is a no catalytic or enzymatic reaction and thus require a higher residence time. Therefore we are having conventional reactors in series.
I was suggesting to stop the top nozzle spray flow and provide a side jet mixer at an angle which will recirculate bottom liquid. Will there be any effect from this system?
Nibou Djamel sir and Rachid Ait Maalem Lahcen sir thanks for the reply.
Does boiling not start with nucleation of water bubbles, before bubble growth, then convective transport to liquid surface before escaping into the vapor phase after acquiring sufficient thermal energy above the surface tension. Agitation will affect bubble nucleation and so inhibit water evaporation.
Suphlay Gupta, In your question, you did not provide the relevant information that you had just revealed in response. As it results, the process is carried out in a cascade of flow-through tank reactors. In such a situation, of course, we can influence the residence time in individual reactors of the cascade. In addition, the absence of an external catalyst will significantly extend the reaction time, which should favor water removal.
The information about the "top nozzle" is also new information. But it's hard to talk about a "conventional reactor". Of course, mixing of the reaction mixture with the "side jet mixer" will be an additional factor favoring the removal of steam to traditional mixing. It can also be used independently.
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