size does matter??

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square_bear

size does matter??

Post by square_bear » Sun Aug 07, 2005 4:27 pm

I have a commercial s/s urn capable of holding 25l of wash. I took the reflux tower off my 5l urn and adapted it to the 25l urn. The result was that the temp was near impossible to control and the product was a foul smelling distillate. I blamed the heating element at the time and went back to the 5l urn.
After reading some of these postings I am beginning to think that my column was too small and would like some advice.
My original column is 37mm dia and 300mm long. I would like to retain the same dia. but how long should I make the next column?
Also, would it be better to increase the dia. of the column?
Anyone had a look at using glass beads from a hobby store as packing?

Fourway
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Post by Fourway » Sun Aug 07, 2005 4:43 pm

glass beads are pretty poor packing compared to copper mesh or ss scrubbers or copper lathe turnings.

you can use a pretty small column with a big boiler if you have very good control over heat input but the shorter it is the more fiddly it gets.

I'd start at 36 inches (about one meter) minimum.


There is a great deal of info about column design in the mother site for this discussion board. You should do some reading there. Someone on here telling you what length you need for X size boiler isn't really useful info... its like someone telling you how long your shoelaces ought to be based on your age.
"a woman who drives you to drink is hard to find, most of them will make you drive yourself."
anon--

square_bear

Post by square_bear » Sun Aug 07, 2005 8:09 pm

Here's another variable to the equation. After close inspection of the element in the urn I find that its rated at 1380 watts at 230 volts. Our mains power is 240 volt so that would mean a proportional increase in wattage. Will I be able to overcome this with a larger column and better cooling?

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Post by LeftLaneCruiser » Mon Aug 08, 2005 1:19 am

square_bear wrote:Here's another variable to the equation. After close inspection of the element in the urn I find that its rated at 1380 watts at 230 volts. Our mains power is 240 volt so that would mean a proportional increase in wattage. Will I be able to overcome this with a larger column and better cooling?
The few extra volts won't add much more power to the still:

P=U*I P=Power in Watts, U=Volts, I=current in Amperes

I = P/U = 1380 / 230 = 6 This means that your element is drawing 6 Amps.
If it runs on the same 6 amps at 240 Volts it will be putting ot 1440 Watts of energy..

But I'm no electrician so in daily life it will be a bit different, but not very much..

Short answer: a larger column may very well solve your problem, but the Volts don't cause it.
More likely it's the overall power of the element. Gives off too much heat and therefore causing too much vapour for the column to handle.

KJH

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Post by Yttrium » Mon Aug 08, 2005 1:58 pm

It is odd that an increase in boiler size would lead to an increase in column variability.

When you switched to a larger boiler did you use the same heating element as you did with the smaller boiler or did you switch to a powerful one?
The future is not set. There is no fate but what we make for ourselves. --John Conner

square_bear

Post by square_bear » Mon Aug 08, 2005 2:09 pm

This was a commercial product with element matched to that size container. I would have thought that if the column can handle the vapour from a smaller urn ( with similiar surface area) then why did it fail on a larger container?

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Post by Yttrium » Tue Aug 09, 2005 6:20 am

In terms of overpowering(aka flooding) a condenser, the actual size of the boiler is irrelevent. The strength of the heating element is what matters.
The future is not set. There is no fate but what we make for ourselves. --John Conner

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Post by Blueraven » Sun Aug 14, 2005 2:39 pm

SB,

I thght the power in needs to match the power out(condensor) + heat losses.

Maybe make a larger condensor.

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