SPP Packing

[sergiolis]

yes Odin, this one running right now is at 30%... let's see
And again SPP is clean and loosely....

[skow69]

So I let the boiler getting cold during last night. I started the run with 23L - 33%ABV and now I have 22,5L - 31%ABV.... but i dismissed 400ml of foreshots, and I cleaned the SPP containing some alcohol too. So I think there is not a leak.
Anyway I'm going to try it right now again and I will check leaks.... But I guess is a different issue..

I would still calculate the expected yield for the whole run and compare it with what you end up with at the finish line. It's just good data to have when you are trying to troubleshoot any problem. 22.5 liters @ 31% gives you 7 liters of ethanol to recover.

Let 'er rip.

[skow69]

The above post was written before I knew we had started another page.

OK scratch the 7 liters.

[sergiolis]

I will do it skow69, of course, it's a good advice. Actually right now is running at 2050W, water condenser out at 47ºC, Take-off at 32ml/min.... and 96.5%ABV, I can't see the boiling liquid in the sight glass but anyway It's in perfect equilibrium. But guys if I try to push more power or more take-off is really very very risky. Tails are coming up or the take-off increase alone..... So I will stay quite... hehehheheeheh. Excuse me about the mess .... but i was a bit worried.
I will wait until I have the new stainless steel condenser and let's see if the problem was the condenser.

[sergiolis]

I got 800ml (foreshots-heads), 3500ml Hearts and 1600ml Tails : 5900ml
And I stopped the run when the temp in the plates thermometer was 95ºC, so there is still some alcohol in the boiler.... I suppose i don't have a leak... The reason I cannot push more power or take-off might be different... Correct me if I'm wrong...

[Odin]

Strange. You should be able to hold 78.3C at the top pretty much all the time, Sergio! Well, if you dial back the needle valve every now and then.

Regards, Odin.

[sergiolis]

Sorry, Maybe I wasn't clear enough. I collected Heads and Hearts at 78.3ºC as you say but when I was in tails I opened completely the needle-valve to collect tails faster and I stopped the run when the Temp was 95ºC. So I think I don't have a leak.... but for an unknow reason I can't push more power than 2050W or more take-off than 32ml/min. I hope to find what is the problem soon....
Odin when I clean SPP the spirals lose some turns of wire .... Is that normal? I can see every cleaning some littles pieces of wire broken...

[Odin]

Yeah, little staples, that's how they look like. Perfectly okay. Just don't throw them back in the column. They have the tendency to stick to the pan you are boiling in, so you can rinse them out of that pan easily and throw them away.

Regards, Odin.

[sergiolis]

Thanks a lot Odin... To solve the problem of limited power and take-off I will wait to test the stainless steel condenser.... because I don't have more ideas....

[Odin]

Makes sense!

Odin.

[skow69]

Sergiolis, I'm glad you don't have a leak. That is one complicating factor you don't have to worry about. How about posting a picture of your rig? I'd like to see what we are talking about.

[sergiolis]

[attachment=2]rig.jpg Tell me what do you need to know and I will take some pictures more....

[skow69]

Thanks, serg, having a visual reference just makes it easier for me to stay on track. I like the mirror above the vent. At first I thought it was a hole in the ceiling for clearance. [Har] What are the specs of your current reflux condenser?

Let's review. The main problem is that you want to apply more heat to reduce your run times but you can't because when you do you get less reflux, right? Then, on the side, one time you had vapor passing the reflux condenser and escaping through the vent, even though the water coming out of that condenser was cool. And another time most of your hearts disappeared and the tails showed up early, but you didn't see any vapor escaping. Is that correct?

[sergiolis]

Hi skow69, that's my condenser:

It's a 6mm OD and from the first ring to the last is 20cm long. Total height is 23cm. But it has a small bent behind the tap. I think it's not a big deal dough because I tested the flow and it can hold more than 1L/min.
Yes, looks like I'm limited to about 2000-2100W and about 32ml/min take-off. If I try to go further I face many issues because the column lose its equilibrium. Usually I got maximum reflux at 1750W and I wait about 20 min of equilibrium. Everything is fine. Then at the same power i collect foreshots at 7 or 8ml/min and then I open the needle-valve to get about 20ml/min with Heads. The issues usually start when I try to go further than 30ml/min with Hearts. For instance on my last run I was increasing the power and the take-off slowly and I got 2050W and 32ml/min. But I tries a bit more, let's say 2100W besides of a bit more take-off and I noticed the column was losing the equilibrium and the Temp jumped from 78.3ºC to 78.4ºC or .5. So I think that a certain point I lost the equilibrium and that line is really very fragile. Because as I said I try to push very slowly. When I noticed the temp raised, immedately I reduced the power and the take-off a bit and it was ok. But I think on my next-last run I didn't noticed soon enough and I lost the equilibrium and tails started to coming up. I tried to correct it several times but I think tails and heads were mixed and it was impossible. So I suppose once you lose the equilibrium in an SPP column, if tails and hearts are mixed it's a big mess. I stopped this run and I restarted the run next day and as I said I got 3500ml of hearts.... so the ethanol was still there..
A different issue but related to the whole problem it's about the needle-valve. If I push too much power, sometimes suddenly the valve changes its take-off and squirts at a bigger rate. My theory is that too much vapour is coming up and when it hits the condenser creates a liquid pool big enough to provoque pressure build up and then the needle-valve squirts. If this happens and I don't notice it soon enough I lose the equilibrium again.
So the main problem is to get the equilibrium beyond 2000w....
Once with a feints run I got 2400w and 44ml/min but how and why I don't know.. It was exceptional.... This time if I tried more power the vapours started to escape through the vent.... but the out condenser water was quite cold.
Sorry about my poor english..
Odin knows that with a 2" column you can go further than 2000w and 30ml/min take-off... and that's why It's a challenge to me to get that rank and to find where is the problem....... Thanks a lot skow69, I really appreciate your attention...

[Odin]

If you loose equilibrium at the top, don't turn the power down. Instead, dial the needle valve back. In a packed column, whenever you change powerinput by just the tiniest bit, your HETP's crash and you loose your tails control.

Like this: Tails will be held back by the 20 distillations you get (as an example). Now, if you dial back powerinput, HETP crash takes place, and you get maybe only 5 distillations. Not enough to keep tails at bay. Manage by take-off only.

Regards, Odin.

[sergiolis]

Perfect Odin! I really understand the theory... But sometimes when a squirt happens in the needle-valve i close a bit the valve but the squirt continues for about a minute, so I have to close the valve still more.. And I agree sometimes I turn the power down so I will try not to do it anymore... Got it!!! The problem is I want to increase my take-off
To a certain extent the equilibrium is very fragile, at least on my experience beyond 2000W. There is a delicate balance between condenser, heat power and take-off and it's really difficult to keep it when I try to go further... little by little....

[Odin]

Just to be sure: your column is 2 inch in diameter? Because if it is 1 3/4th your numbers would be okay ... It is the smallest diameter part that counts.

Regards, Odin.

[Edwin Croissant]

.

But sometimes when a squirt happens in the needle-valve i close a bit the valve but the squirt continues for about a minute, so I have to close the valve still more..

If your condenser has a too small ventilation hole at the top it could be that your column is suffering from fusel oil induced hiccups. Fusel oil is trapped in the column and and after a while it will reach the de-mixing threshold. The de-mixing causes a drop in boiling point resulting in a flash evaporation. This pushes some of the column content up resulting in the temperature spike and escaping vapor. If the ventilation hole is to small the pressure spike will cause the squirting. See this thread and this thread for more information.

[skow69]

Hi serg. That is quite the convoluted collection of symptoms you've got going there. Actually, it sort of reminds me of the troubleshooting I used to do in my professional life, back in the days when I was a productive member of society. One of the pitfalls of troubleshooting a complex system with multiple symptoms is that problems can interact with each other in ways that make it impossible to determine whether specific symptoms are the result of a common cause or actually unrelated. It is easy to get overwhelmed by the apparent scope of such a situation and end up chasing your tail looking for that magic bullet that will fix everything. Sometimes it is more productive to try to isolate one issue at a time and deal with them individually. If you can remove some of the minor problems this way, then the remaining symptoms often become much more manageable.

For instance, I don't see any reason why your reflux condenser should be incapable of doing its job on this still. I would suggest that we start by tackling that issue without assuming that it is all wrapped up with everything else. When it is reliable, then you can take that off the table and move on to the next step.

[sergiolis]

Hi Odin, my column is ID 51mm and (54mm OD) So i guess it's what you call a 2". We usually don't talk about inches...
Hi Edwin, these are my vents:

Do you think is enough? You know it better than me...

[sergiolis]

Sorry Skow69, I didn't see your answer... yeahhh! you are right... It's my first coil condenser and I love it... just I'm so disoriented that I don't know where to aim...

[Edwin Croissant]

Hi Edwin, these are my vents: Do you think is enough? You know it better than me...

Looks good. Only thing I can come up with is a intermittent blockage, is the take-off line free? Or a really bad valve.
What about your slant plates? It looks like the bottom one go all the way to the other end?

rig.jpg (27.92 KiB) Viewed 4633 times

[sergiolis]

Hi Edwin, I think I get blockage when I push the power more than 2000W, at least looks like that. The take-off line is free. And the valve is a really good one (theoretically if we look how much it cost): http://uk.rs-online.com/web/p/process-n ... s/4325230/" onclick="window.open(this.href);return false;" rel="nofollow
The slant plates are ok... I started to cut the wrong side, but I noticed I was wrong soon and I didn't cut it, I just scratched a bit with my Dremel but then I decided to put solder also there....
I tested again my coil condenser and connected it alone to the water tap and it holds about 2800ml/min with the water tap completely open. Actually it stops some water because without the coil the water tap drips about 7500ml/min. But I think that pressure back is normal.

[sergiolis]

Just a comment.... I saw a distance recommended of 30mm between the end of the dual-coil condenser and the top slanted plate, but I have 20mm.... If you think that could be a problem I could fix it...

[Odin]

As long as the cooling tube does not hang in the liquid or is touching the plate or the column, you will be fine.

My coolling tube is even closer to the top plate. I think I posted a picture about it a page before ...

Odin.

PS: those vent holes are MORE than big enough, Serge!

[sergiolis]

Ok Odin!!! thanks... I will try in the next run take a look at the condenser with a torch... just in case

[Edwin Croissant]

And the valve is a really good one (theoretically if we look how much it cost): http://uk.rs-online.com/web/p/process-n ... s/4325230/" onclick="window.open(this.href);return false;" rel="nofollow

According to the web page this valve has a blunt stem tip (30 degrees) and my experience is that with these valves it is very hard to control a small flow. A small temperature difference between stem and housing can have a large effect in flow. These valves also have a tendency to close shut after a while, they are not stable. According to Parker: Three stem types are available. A regulating stem type (N) provides coarse regulation with metal-to-metal shut-off in liquid service. A blunt R stem type is typically used for on-off control of liquids. The PCTFE stem type is recommended for tight shut-off and coarse regulation in both liquid and gaseous service.

You might be better off with the needle stem: M6A-V4LN-SS. See the page 3 of the pdf datasheet on that page for for more information.

I had to modify the stem of similar valves once to get a finer control

[Edwin Croissant]

On the Dutch forum some people are using this valve with these couplings and claim good results. You need to loosen up the stem seal a little bit and use some silicon spray to get it easy going.

[sergiolis]

Oh Edwin.... what's the function of silicon spray? is it safety?

[Edwin Croissant]

Lubrication