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FOULING NIGHTMARE

FOULING NIGHTMARE

(OP)
My name is Francisco Di Buono, I’m a mechanical engineer working for an alcohol factory named Porta Hnos. I’m writing to you from Argentina, so because my English is a little bit rusty please ask me if something is not clear.

In the past 4 year we have start up 3 ethanol plants (alcohol from corn fermentation). The 3 of them were bought to a Chinese company named JINTA. They have been working Great with any Stop for cleaning since the startup.
Beside this we have made 2 more distilleries to upgrade the alcohol quality with our own engineering and they are also working perfect (they were calculated with Chemcad).

But nothing is a bed of roses so here comes the main reason of this post. 6 month ago we started working in a development to add modular distilleries to our main plant. They should be able to process 5 m3/h of fermented mash containing 13% of alcohol and the energy source is direct vapor. But we are stuck in the Beer Stripping section. We have tried everything, 3 different types of columns (sieve, bubble cap and trays in that order) and all of them reported the same problem. Mash sticking in the upper trays.

First we started with sieve trays of 12mm they last 2 days (all the time since star up the delta pressure between the bottom and the top of the column was decreasing) and star loosing too much alcohol (1.5%) from the bottom. After that because our Boss have worked well with bubble caps in a distillery at Arcor (a candy factory) we tried that. Also fail at the same time. At that instance the separation or trays was of 350mm. so we decided to make a tray of 550 mm. same effect. A curios fact of the bubble cap trays is that at some point after half of the bubble caps were cover up it didn’t advance more.
So our last try was using the same technology that our beloved Chinese columns... "Valve Trays". 2 days and stuck again.

All of the columns were of 750mm diameter with 50 mm of weir height and 35 mm of downcomer clearance and flood of 70%

Another rare symptom is that de delta pressure of the column was greater than what chemcad says (this is probably because some property of the corn mash is not well specify). Besides that always the initial hours are off perfect working.

The rare thing here is that the Chinese columns work perfect. Clearly we are not seeing something but here in our country we have no experience voice to give us advice. So I will be extremely grateful is you could provide me some tip based on your experience.

RE: FOULING NIGHTMARE

taraleta

Just to be clear.
Is the process a JINTA five column process with one heated and the others using the steam from the rectification column?
Is it the Mash column that is fouling?

Regards
Ashtree
"Any water can be made potable if you filter it through enough money"

RE: FOULING NIGHTMARE

(OP)
WE HAVE 2 DIFFERENT PROCESS. ONE FOR qUALITY ALCHOL THAHT HAVE 5 COLUMNS. THE RECTIFICATION COLUMN HAVE A REBOLILER AND USE STEAM AS ENERGY, THE OTHERS COLUMNS USE THE STEAM OF THE OTHERS WITH REBOILERS. THE MASH COLUMN IS OPERATED UNDER VACUUM. IN ONETHER PLANT WE ONLY HAVE 2 COLUMNS A MASH COLUMN A COMPOSITE COLUMN (HALF MAS HALF RECTIFICATION AND A ONETHER RECTIFICATION) IN THIS COLUMNS THERE IS NO VACUUM.

RE: FOULING NIGHTMARE

Hello, have you considered using a packed bed with fouling resistant liquid distributors? Somehting like y-slots or drip tubes with slots might work depending on the fouling and quantity.

RE: FOULING NIGHTMARE

You can't feed a stream that contains solids into a distillation column without fouling the column internals, regardless of the type of trays or packing. Separate the solids from the column feed stream, and your problem will go away.

RE: FOULING NIGHTMARE

As a follow up to don1980, screw press separators have been used successfully to separate mash or grain in distilleries.

RE: FOULING NIGHTMARE

A decanter centrifuge before the column would be a good choice as well.
Though I did see a flow scheme where they ran the mash through one column first. But they also show a plate heat exchanger in the process and that looks like a disaster waiting to happen.

Regards
StoneCold

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