[tripton]

Hi everybody,
I have a little problem and I´m looking for ideas to solve it. Perhaps someone may helpme.
I must assemble a reactor filled with a fixed solid. The problem is that the particles size of that solid is very small and the after some minutes, the column get clogged and the liquid pressure drop gets very high.
Someone have some suggestion ?

[Montemayor]

I don’t understand what you mean by a problem.  Is it a problem that exists? – or is it a problem that you anticipate?  The two are very different.

If the problem is one that is existing, the answer is to buy your catalyst in larger sizes.  However, that will probably mean that the catalyst payload in your reactor will be reduced – and so will your production rate.  But that is something that has to be suffered due to a design mistake in selecting catalyst size that is too small.

If you are anticipating the problem, then change the reactor size to one that will take a larger catalyst size or a catalyst shape that will yield a lower pressure drop.

With a fixed bed reactor, you usually only have those two factors that you can vary: catalyst size and reactor size.  Here, I am assuming that you cannot increase temperature or pressure should those be aids in accelerating the reaction speed and conversion.

[technologist]

U need to specify few things.

• What is the size of catalyst particles.
• Which liquid U r using & its physical props
• What do U want to do with them - Kind of reaction
• What is the reactor design - Any special configuration

Only after this somebody can suggest any better method.

[tripton]

Thanks for wour answers.
I´m trying to design a column with a new filling material. This material has a pore size between 0,4 and 0,7mm aproximately and is flat (is not a standard catalyst pellet). I test in very small amounts and I´m trying to scale up it.
The reaction is physical absortion (follows a Langmuir isotherm).
The fluid properties are almost the same that water (is a water dilluted solution).
I haven´t the reactor design. I must look for the best design. I need a residence time about two hours.

[technologist]

If U have sufficient liquid pressure or can consider it, then try to feed liquid from bottom and keep your catalyst in fluidized state with holding mesh at top & bottom. Few alumina balls of smaller size may also be considered at the bottom for good hold of the material.

I hope it will work.

It will avoid clogging.
It will reduce pressure drop in normal operation also.
It will avoid channeling.
It will provide max catalyst utilization.

[tripton]

Thanks again Technologist. That´s a good idea.
I already thought in some kind of fludized solid reactor and really is one of the options to be evaluated.
One problem in that case, is that I will need higer reactor volume and/or lower liquid flow. That´s because the solid is not really a catalyst. Is a kind of absorber, but perhaps is easier to imagine it like a ion exchanger because after de absorpton I will make a desorbtion circulating other solution.
I need about 4g of solid by each liter of solution processed. Then I must keep as lower as possible the expansion factor of the bed and perhaps it will require some automatic control of the pump according the clogging conditions (because I will need a small pore holding mesh).
That´s some reasons why I´m trying to look for other ideas to compare.