sergiolis wrote: ↑Fri Sep 23, 2022 3:52 am
At Heads it's 150ml/min, at hearts 180ml/min, 9 Kw for a 85mm ID Column, 130 cm Packed section with 4,2x4,2x0,2 SPP seven points star.
180 X 60 = 10800ml or 2.85 g/hr of who know's what ABV.
How big IS your boiler?
Is this a commercial operation or are you making fuel?
Are you trying to make more than 3 gallons/hr?
If your only restriction is the 13Kw, why not run your 3.5" at 9Kw, 10800ml/hr and a second 3" column at 4Kw on a second boiler?
sergiolis wrote: ↑Thu Sep 22, 2022 4:24 pm
Thinking on adding 2 liquid distributors just in case liquid is dripping on the walls.
I'm a total newbie about SPP. But this got me thinking.
Centering rings are notorious restricting reflux and causing flooding.
I wonder how multiple centering rings with SPP in between each ring would act?
sergiolis wrote: ↑Thu Sep 22, 2022 4:24 pm
Thinking on adding 2 liquid distributors just in case liquid is dripping on the walls.
I'm a total newbie about SPP. But this got me thinking.
Centering rings are notorious restricting reflux and causing flooding.
I wonder how multiple centering rings with SPP in between each ring would act?
I also can't talk specifically about SPP , but I imagine that if you centre or direct reflux to the centre of any packing , that the area of packing immediately to the sides of the centred flow will not be areas of high efficiency as although there may be rising vapour , there is no immediate descending reflux .
So in my mind , disturbing the continuity of the packed area with centring devices is going to be detrimental to the overall efficiency of the packed column.
Yummyrum wrote: ↑Fri Sep 23, 2022 9:41 pm
...disturbing the continuity of the packed area with centring devices is going to be detrimental to the overall efficiency of the packed column.
I agree, but it seems SPP plays by a different set of rules than other packing, or so I've heard.
I don't know. But if someone wanted lots of localized flooding for SPP.
Multiple centering rings could do that.
Yes! on my experience SPP works much better when it's flooded and really wet along the entire length of the packed section (well, is better to flood just until you are near the top of packing to avoid a surprise). It works with a certain turbulance so I think it will minimize an uneven distribution.
Anyway I need to try it. The only thing is I just Reflux occasionally. However, it's nice to have time to think about improvements.
sergiolis wrote: ↑Sat Sep 24, 2022 4:05 am
my experience SPP works much better when it's flooded and really wet along the entire length of the packed section
In my view there is a misunderstanding of what a flooded column is and what a semi flooded state (SFS) at the top of the packing is and how it's achieved.
From many experiments done to get an understanding on what all happening during a SFS, I've never observe the whole column being flooded with distillate other than at the top of the packing.. if one experience flooding of the whole column then some form of restriction is taking place, and without some sight glass, one can not tell which one is happening.. one can have a SFS and still create some flooding over the top of the column..
Mars
In the picture below, a sight glass position about mid way show no sign of column flooding, yet there's a SFS at the top of the packing..
Attachments
Semi Flooded State (flooding only on top of packing)
" I know quite certainly that I myself have no special talent. Curiosity, Obsession and dogged endurance, combined with self-criticism, have brought me to my knowledge and understanding "
kimbodious wrote: ↑Sat Sep 24, 2022 2:30 pm
Great photo Mars! It clearly shows a fluidised bed on top of the packing but no flooding in the column.
Thanks.. as I've been toying with this behavior for a few yrs now, still haven't put my finger on exactly how or why it occurs, but hopefully one day I will, in the meantime, I'm an advocate of the SFS behavior..
What I've learn comes from running and observing went I run the flute, and I've of the view that it similar it behavior, as the ABV does improve..
I've got other pictures which demonstrate that the column does not flood, but there's an interrelation between the vapors and the packing throughout the column length..
Mars
" I know quite certainly that I myself have no special talent. Curiosity, Obsession and dogged endurance, combined with self-criticism, have brought me to my knowledge and understanding "
It,s actually flooding.... It, s just a matter of terminology... We can call it flooding, semi-flooding, technical papers name this point as flooding velocity, etc... These bubbles start at the bottom and go up... If we don,t stabilize it and they increase a bit they will arise the condenser and then it will actually flood. But it,s true that we cannot see the bubbles or this turbulence along the entire column, however is there... (we can only see the top layer bubbling of this flooding, semi-flooding or whatever we wish to call it) But packing is dense and if we maintain this layer of bubbles near the top of our packed section we are stretching the efficiency of SPP dealing to a high mass transfer during their lift...(vapour/liquid contact enhanced) I can see a big part of their route through a glass column...
sergiolis wrote: ↑Sat Sep 24, 2022 3:53 pm
It,s actually flooding.... It, s just a matter of terminology... We can call it flooding, semi-flooding, technical papers name this point as flooding velocity, etc... These bubbles start at the bottom and go up... If we don,t stabilize it and they increase a bit they will arise the condenser and then it will actually flood. But it,s true that we cannot see the bubbles or this turbulence along the entire column, however is there... (we can only see the top layer bubbling of this flooding, semi-flooding or whatever we wish to call it) But packing is dense and if we maintain this layer of bubbles near the top of our packed section we are stretching the efficiency of SPP dealing to a high mass transfer during their lift...(vapour/liquid contact enhanced) I can see a big part of their route through a glass column...
Yup. Some people flood on purpose. I don't get it. Maybe it is a flavor thing
Now I know how you claim azeo so easy, it's based on a meat thermometer. :lol:
sergiolis wrote: ↑Sat Sep 24, 2022 4:05 am
.... my experience SPP works much better when it's flooded and really wet along the entire length of the packed section (well, is better to flood just until you are near the top of packing to avoid a surprise).
The packing being wet its entire length is true.
But that's not the way it works on top. The top of the packing looks like its boiling.
Because the reflux raining off the RC hits the slightly hotter packing and flashes into vapor.
This is happening the whole length of the packing, but only visible on top.
If you see rising liquid in the packing, then it's truly flooded and that isn't good.
So sorry guys, It's really complicated for me to talk about these slight terminology differences but we are talknig about the same
The top of the packing looks like its boiling
: Yes!!!!
Because the reflux raining off the RC hits the slightly hotter packing and flashes into vapor
:
Not exactly. I can also see (through the glass column) this boiling line coming from the bottom. Once it overcomes the packing barrier it becomes more visible and you can see boiling bubbles. However is coming from the bottom due to heating power and differential pressure...
This is happening the whole length of the packing, but only visible on top
The volume of vapour rising is tens of times greater than the volume of the falling condensate. A lot of the bubbling you see in the fluidised bed on top of the packing is the rising vapour rushing through (think spa). What you are seeing as a boiling line is not liquid rising up from the base of the column, that would be puking. The boiling lines are zones where the rising vapour is interfacing with the falling condensate.
--
50L Beer keg boiler, 2200W element Modular 2" Pot Still
opinions are free and everybody has them, experience costs you time
I will not argue, but under the boiling line the packing (all of them) is much more wet than packing above the boilng line.
That's why semi-flooding provides a higher mass-transfer efficiency.