Author Topic: Glyc drop at ambient temp  (Read 1601 times)

Offline Soft top

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Glyc drop at ambient temp
« on: February 08, 2019, 09:30:05 AM »
I was reading on here recently about processing at ambient temp and thought I would give it a try.

I usually process at about 60 degrees, settle for an hour and then drain the glyc. I do that for both stages with prewash water at end of second stage.

How do those that process at ambient temp get the glyc to drop?

The first time I processed at ambient it took overnight for the first stage glyc to drop and the second stage with prewash water never dropped and I had to heat it first.

Yesterday I had another attempt. First stage finished at 10am but the glyc has still not dropped this morning so it is now being heated.

Am I doing something wrong?

Offline dgs

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Re: Glyc drop at ambient temp
« Reply #1 on: February 08, 2019, 06:26:55 PM »
I've never had a problem with the glyc dropping but it does take a lot longer the cooler the process is. My normal process temp is 30degs, I do 1st stage then leave overnight, the glyc drops ok.

I like my 1st stage dropout no more than 0.5mls (closer to the reaction end point than most people have) This way it's easier to calculate the amount of glyc left in suspension after S2 so the same amount of water can be added.

Glyc left in suspension after S2 is 3.0 litres + volume of methoxide added for S2  Using this simple little calculation it's never more than 0.5 litres out.

After adding 4 litres or so of water I only pump for 5 mins then immediately bubble which I find releases the wet glycerol better than just letting it stand.

My 3x glyc washed oil shows a 10/90 dropout of 8mls so for a 195 litre batch size I can get to the <0.5 dropout by adding 600gms of KOH, 1200mls of ASM and 20litres of methanol.

Hope this helps.

Just to add, I know my 30deg reaction is hardly ambient but in the midst of Winter if you really do use ambient temps it can cause problems.
« Last Edit: February 08, 2019, 06:31:22 PM by dgs »
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Offline Soft top

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Re: Glyc drop at ambient temp
« Reply #2 on: February 09, 2019, 10:54:24 AM »
Ah, right, thats where I have gone wrong. I read through previous posts before trying it and saw lots about processing at ambient temp but must have missed any reference to 30 degrees or glyc drop times.

But its got me thinking now about how much electric is used.

When the outside temp is cold I have to raise the temp to 30 for 1st stage and then raise it to 30 again a day or 2 later for 2nd stage.

The way I used to do it was raise the temp to about 50 or 60 and then turn the heater off. Process for 1 hour then settle 1 hour and drain glyc. Then immediately do stage 2 for 1 hour, add 5% water, mix for 10 mins, then settle 1 hour before draining glyc and then water wash.
All the processing done in about 4 hours.

Im not sure about the maths but when the temp in my shed is only a few degrees would heating the oil with 3kw heater to 30 degrees twice use more or less electric than to raise the temp to say 55 degrees once?