[technologist]

30% MEG + water antifreeze system has freezing point of -16°C.
What will happen if I chill 30% MEG-Water solution to say -10°C. Will it separate out any water as Ice OR Not?

[P]

Shouldn't do - should all freeze at -16deg.

If this is a really important application - put yourself at ease by testing a litre at -10 to -12 deg just to make sure.

[DrCMS]

How are you cooling the mixture?
Is the MEG/water mix running through a chiller as the coolant medium? 
If it is be aware that the evaporator temperature will be lower than -10°C to achieve a coolant temperature of -10°C.  Try more glycol or switch to MPG.

[technologist]

No, actually I am looking it as a cost effective method for the removal of water from MEG compared to distillation/Evaporation systems.

[Donaldson Tan]

30% MEG + water antifreeze system has freezing point of -16°C.

Is this an azeotrope?

[eugenedakin]

Hi technologist,

The mixture is an azeotrope (as geodome has inquired).

When the freezing point has been reached, this homogenous mixture will freeze together, and it will not separate out into its individual components.

I hope this helps answer your question.  If you have any suggestions or comments, feel free to submit them.

Sincerely,

Eugene

[technologist]

Thanks Eugene
I Believe so, but was not sure.

Can U suggest any ref for phase diagram of this system.

Now, is there any other alternate possible to separate out MEG & Water into its component to any extent possible.

The reason for posting this question is only Commercial aspect. We are manufacturing MEG @500 TPD. After reaction it contains ~11% MEG solution which is concentrated to ~80% MEG in 3 stage evaporators (MEE). This consumes lot of heat energy.

SO I am searching for options like, Icing of water (May be an stupid Idea, but I read it somewhere) OR liquid liquid extraction (LLE). However dont know suitable solvent for this.

Any other Idea is welcome for the separation to any extent? Even if its able to separate any fraction say by 30 - 60% that will reduce my cost significantly.

[eugenedakin]

Hi technologist,

Its intreguing that you mention your situation.  In my former position, I developed and many industrial separation techniques (due to necessity out of time constraints) by taking off-specification product and making it near original purity specifications.  This was usually performed in a minimum of one - 20,000 litre batch per day.

The most common one-pass method that I used for separating MEG from water (and having almost 99% pure MEG) was to centrifuge it.  MEG is denser than water.  I am unsure as to the difference in energy requirements and maintainence energy differences between evaporation and centrifuege separation techniques.

The good news is that centrifugation works, the bad news is that I am unsure if it is more efficient/reliable (due to mechanical maintenance) than evaporation.

I hope this helps, and feel free to ask more questions.

Sincerely,

Eugene

[technologist]

Exciting Info Eugene. Thanks for this.

Let me work out Economics. (I feel more confident when U say that U have already worked on MEG Water System at Industrial scale of 20 KL batch).

So for this, if u can recollect some info, probably this can give us some direction.

For this 20 KL size
1. What was the actual batch size? (20 KL is for one day which may be diff / batch if no of batches were more than 1)?

2. What was the initial MEG concentration? I presume final MEG was >99% as U said, correct me if I'm wrong.

3. What was the batch running time?

4. What was the motor size for centrifuge?

5. Was it a normal centrifuge OR any special design?

Hope U understand the need of this.

It will let all of us know that Improvements come only if we start silly thinking like this. I may or may not succeed but I'll learn from it.

[eugenedakin]

Hello technologist,

Here are the answer to your questions:

1) At one time, there were 3 x 20 m3 batches (there were many more than this, and this was the largest batch in one day).

2) The initial MEG concentration was approximately 42 %, and the final concentration was over 99 %. 

3) The batch running time was approximately 8 hours.

4) The centrifuge was small (electric motor, 120 volts), approximately 24" diameter.

5) It was a generic centrifuge. 

I wish you the best.

Sincerely,

Eugene

[technologist]

4. What was the motor size for centrifuge?

4) The centrifuge was small (electric motor, 120 volts), approximately 24" diameter.

Actually I meant kW rating of motor OR power consumed.
I can't figure out from this motor size as its different in India.
OR
If anybody can tell me the most probable kW rating for this size of motor talked by Eugene.

Eugene,
Its really going to help me a lot.
U R again a great help to me. U deserve 2 Scooby. Here it goes.
______________________________________________

Do U have any idea on centrifuge size (Diameter Or Volume Or Weight Capacity)



Thanks

[eugenedakin]

Hi technologist,

I am taking a guess at this, but the motor is probably between 1000 - 1500 watts (120 volts x 10 amps?..maybe?), the centrifuge diameter was approximately 24 inches, and had two 1 inch ports (one for less dense fluid, and one for higher dense material.

Chuckle .. you are welcome for the help.

Thanks for the scooby snacks !! 

Sincerely,

Eugene

[technologist]

Wonderful It will be cheaper than distillation.
So all should get benfited from this FINDING of Eugene & myself.
Now I am goin to convert it for Commercial level in my plant.

Well Eugene,
I have one more info to share. I found that Phenol can dissolve MEG completely so can water. But Solubility of Phenol is only ~8-9% in water @20°C. But I am not sure if I can separate it that way using LLE. (I know in this case Phenol loss in water will be an issue, So searching more).

OR

if I use MCB which has 6% solubility of MEG & almost insoluble in water then probably that would be better than Phenol.

Just sharing all this info.

[technologist]

I guess than U have fed 20 M3 in ~8 Hours in your centrifuge as continuous feed.
Am I right?

[technologist]

Eugene
I am bit skeptical on success of Centrifuging for Separation.
(I am not doubting on your batches - 20 M3 size in 8 hours itself is sufficient to prove it)

But the characteristic of MEG+Water (Completely Miscible) made me to prompt this.
Is it really possible??

If I see Density Nos - Hope is still alive.
If I see Miscibility - I'm drowned.

Results of your batch are already there - No reason to doubt about.

Actually I'm depending on this project a lot. Therefore, want to make it sure.
I hope U wont mind.

Can U tell me centrifuge suppliers who can give it to us.