"Will a slant plate VM Design Work?"

[rad14701]

Here is a quick draw-up of a 2x2x1 Slant Plate VM head... It has two variations of plate angle and also two variations of plate depth, 50% and 33% (.25" past halfway for 2")... I have used this site for the volume calculations for various column sizes... For this application L=1, R=column radius, r=0, y=any arbitrary value... I just click Compute Volume and then goto step 4 and generate a table of incremental values... Every column size needs its own chart...

I actually like this idea better because it could be a bit tricky trying to get the elbow inside the Tee without a shoehorn or butchery... This issue came to mind while drafting the previous examples...

Okay, minime, off to your mad lab to do some testing...

[HookLine]

Another possible way to do that without using plates.

VM Stream Split.jpg (4.38 KiB) Viewed 8299 times

The vapour stream splitting ratio would be determined by two variables. One is the ratio of diameter of the take-off pipe to the diameter of the main column. The other is the angle of the cut on the take-off pipe.

Also, if the diameter of the take-off pipe is significantly less than the column, then there will be a gap around the sides of the take-off pipe inside the column. So the take-off pipe could project all the way across the inside of the column to the opposite column wall, and there could still be enough room at the sides for vapour to pass up to the reflux condenser.

[punkin]

Punkin, your column could quite easily be converted immediately if you're up for it. Probably wouldn't take more than an hour to slip a plate in there. Wouldn't do any good though if you've nothing to run.

Don't think i'll play with the column i got. If i was gunna play with it, i've got pipe all the way from 3/4 to six inch on my pipe rack, so i'd go for the 80mm stuff, and post the one i've got for sale.
That's what i intend to make my mates column for him outa, and quietly watching developments here before i do








It's truely fascinating, but i have limited use for the product.

[minime]

Just yesterday I was offered 6 feet of 4" copper for the princely sum of 2 gallons of 95.6 white rum. I don't think I'll ever get another chance at 4" copper and I don't have the rum to spare so here we go again. I've ordered supplies and hopefully I'll have a shiny chunk of 4" copper by the end of November. (don't think I'll ever use it but you never know ) In the meantime I'm going to convert the Bok to the new configuration and shorten it up to 40".
[snip]
Thanks to Absinthoman for this idea BTW

Told you that you wouldn't be able to resist trying more stuff. You didn't even last a week!
Or to put it another way:

Laughing_RoflSmileyLJ.gif

Oh crap I know, I know. I actually did say no at first, then I came home and did the area calc and realized it's getting pretty close to twice the capacity of the 3". Then when I called him back I tried to negotiate for next spring but he wants the rum for Xmas season. Believe me it's not very comfortable out there but it's not yet cold enough to freeze up water lines as the waters running. It'll get that cold here but not for another couple of months.

I have to say that even the 3" column is fairly awkward and unwieldy to handle. It's not that heavy but when you get that kind of hight perched it gets wobbley. Anyway the 4" will likely never get used unless it gets a permanent mount with a separate feed of some sort. I'm quite happy with the performance of the 3" but I just couldn't pass up the deal.

[rad14701]

As HookLine pointed out, you could simply use an angle cut on the cross tube, but calculations would be more difficult and high take-off rates wouldn't be possible... Using the slant plate would be the most accurate method of getting a high percentage take-off rate...

I just sent this drawing to minime which shows both 50% and 70% volume plate placements... With a 3" T the 70% is at the 2 " mark, whereas the 50% is at the centerline...

[punkin]

Are we concerned at all about pruduct distribution in the mesh here, or do we all think that's gunna sort itself out with wicking?

Also, what effect do you think this plate, or indeed the cup, will have on the vapours when the valve is closed and you are chasing equilibrium?

Will it be the same process in a longer time frame?

Just picturing it, the vapour speeds up after the void to the valve is full of vapour to get through the bottleneck, and finds the condensor just after. Does this faster vapour then need a more efficient condensor? Or does it slow again immediately after passing the obstruction?

What if the obstruction was removable?
If it was fitted to the bottom of the condensor or folded up when not required or something?
Would that make the stabilising process more efficient?

[maoule]

Hi all,
I'm newly registered but have been following this thread for a while. Thanks for all the wonderful research and info.

What if the obstruction was removable?
If it was fitted to the bottom of the condensor or folded up when not required or something?
Would that make the stabilising process more efficient?

What about some sort of butterfly valve? And what effect would it have on the valve downstream?
maoule

[punkin]

Yes, like a carburrettor

[minime]

Are we concerned at all about pruduct distribution in the mesh here, or do we all think that's gunna sort itself out with wicking?
Also, what effect do you think this plate, or indeed the cup, will have on the vapours when the valve is closed and you are chasing equilibrium?

I going to go with the 1/2 way point and the steeper angle. According to Rad's numbers that's about 6% more area than I have currently with the inverted funnel. I'm thinking reflux distribution will actually be better than my inverted funnel. All the reflux on the plate will be deposited to the centerline of the column and the other half will be evenly distributed. I already have a 3X3X1 tee to spare so I should be able to prove or disprove the concept within 2 or 3 weeks.
As far as equilibrium I have not encountered any problem with the current set up. My reflux condenser is two winds of 1/4 copper and then I soldered on a piece of 5/16ths for a third wind with the return running up through the centre of the coil. Works like a charm with very little restriction. It's only 8 inches long and I run it very hot with no vapors getting loose. It is wrapped in copper mesh also.
I really do think this could prove to be the ultimate VM design for efficiency, ease of build, and ease of operation.

Thanks again to Absinthoman for the idea

[rad14701]

I really don't think that having the reflux drop exactly into the center of the column is as important as people make it out to be... Regardless of where the reflux drops, the rising vapor always seeks the path of least resistance and if that point happens to be near the column wall at a given height then that's where it's gonna go... The column should be of equal temperature throughout the packing volume with only minute differences caused by packing density discrepancies... Even industrial tray-based columns don't reflux down the exact center...

Sounds like minime is gonna have quite a collection of heads to use for his 3" column...

minime, I think your choice of plate configuration is the way to go... It would at least make a good base-point point from which to make future modifications...

[maoule]

minime, I think your choice of plate configuration is the way to go... It would at least make a good base-point point from which to make future modifications...

Would an elliptical shape ( instead of the straight edge ) slant plate be of any benefit. It seems you'd be able to collect vapor further into the diameter but still maintain the 50% ratio.

[rad14701]

Would an elliptical shape ( instead of the straight edge ) slant plate be of any benefit. It seems you'd be able to collect vapor further into the diameter but still maintain the 50% ratio.

The only real benefit would be where the reflux that falls onto the plate runs off, but you could achieve the same effect more easily, and still retain a more accurate calculated volume offset, by using a drip tab... Conversely, using an ellipitcal plate would force the rising vapors more to the walls of the column... Whether this would be problematic or not is just as debatable as reflux dropping into the center of the column...

One thing is certain, by constructing the head using a T it becomes possible to make some alterations that can't be made in a long column...

[minime]

Would an elliptical shape ( instead of the straight edge ) slant plate be of any benefit. It seems you'd be able to collect vapor further into the diameter but still maintain the 50% ratio.

The only real benefit would be where the reflux that falls onto the plate runs off, but you could achieve the same effect more easily, and still retain a more accurate calculated volume offset, by using a drip tab... Conversely, using an ellipitcal plate would force the rising vapors more to the walls of the column... Whether this would be problematic or not is just as debatable as reflux dropping into the center of the column...
One thing is certain, by constructing the head using a T it becomes possible to make some alterations that can't be made in a long column...

Yup, I want to keep it simple and straight forward for now and see what happens with something that's easily duplicated. No telling what the future may hold though.........I'm never again gonna say I'm done for the winter

[maoule]

[quote="rad14701"One thing is certain, by constructing the head using a T it becomes possible to make some alterations that can't be made in a long column...[/quote]
I'm saying using the plate with the tee as I assume you are. I'm just looking for an easier/cheaper way to get a similar result. BTW it occurred to me...when fabbing the plate, add a small tab to the back of the plate to make it easier to remove when unsoldering.

[minime]

BTW it occurred to me...when fabbing the plate, add a small tab to the back of the plate to make it easier to remove when unsoldering.

An excellent idea, I be sure to do that. Any more good suggestions before I embark on this path?

Maoule are you fabricating in 3 inch or 2 inch?
Looks like you're way ahead of me so please share your results so we may all benefit from your knowledge

[maoule]

Maoule are you fabricating in 3 inch or 2 inch?
Looks like you're way ahead of me so please share your results so we may all benefit from your knowledge

I have 5' of 2" left from my bokmini/7.75 gal. sanke project and recently acquired a 15.5 gal sanke. After reading your build and showdown threads, I think I have the VM bug. I built a Smiley offset +/- 10 years ago and haven't done anything for 5,6 years. After building the bokmini from the research I did here, I was amazed at the performance of the bokmini compared to my old system. So no, I'm not way ahead, just trying to catch up. Thanks again.

[glassman]

as for the butterfly comment i machined a rather nice one a while back but vapor will find it's way out every little space ie. where the shaft goes thru. and it will work it's way around the valve plate so you always get a drip outt the condensor. found no good way of sealing the shaft without useing the you know what O rings. so i abandond that idea. gman

[Hawke]

Yep, the butterfly would have to match the column perfectly to seal. Then tight PTFE bushings for the shaft.
Just my opinion, I think the inverted funnel is going to be the better idea.

[minime]

I'd forgotten why I had this tee sitting around. The center band on this bugger is almost 1/4" thick and will be hard to solder I think. I used a slightly steeper angle but took the plate only half way over which actually puts the bottom edge of the plate 1/2" below the 1" takeoff port. I'll be soldering in later today and hopefully can get a picture up of the finished head.

[punkin]

as for the butterfly comment i machined a rather nice one a while back but vapor will find it's way out every little space ie. where the shaft goes thru. and it will work it's way around the valve plate so you always get a drip outt the condensor. found no good way of sealing the shaft without useing the you know what O rings. so i abandond that idea. gman

In this instance the butterfly would not have to seal and stop vapours working past it to the condensor, we have a valve for that. We merely need it to direct an amount of vapour to the condensor, still need some to get past to make a reflux ratio.
I think you could do it with an internal shaft, and a controlling rod coming up through the condensor to eliminate any need to drill the column at all

[minime]

As it turns out the guy with the 4" copper was more than generous when he said six feet. It's only 4.5 feet. He offered it for less but I turned down the deal. I am going to continue on this project because supplies are on the way and I'm pretty curious. I've decided to try and get away with the little 1/2 by 18" liebig that worked so well with the bok head. I also figured there's not really any need for the 1" ball valve either. It reduces to 1/2" immediately after the valve so what's the point. This brings the build cost down considerably because now I only needed a 1/2 inch union. So all in all the entire apparatus hanging off the side of the column will be very light weight. I have another liebig on hand if this one can't handle it but I think it will be fine.
I'm thinking if this works a guy could likely get away with poking a 1/2 pipe into a column under a hood and have a super cheap high efficiency VM column with all the benefits that VM offers and no difficult to source parts required. Wouldn't that be awesome

[punkin]

Looks the goods MM, the idea of just branching from the column occured to me in my build. You would be able to do it either, as you're suggesting, by drilling the appropriate size hole in the column, or for better strength and neater looks, by having someone with access to a branch forming kit pulling a branch outs your column and soldering to that.

I'm think that to reap the benefits of all that vapour being redirected into the branch, it should be larger up to the condensor, rather than smaller?
Wouldn't it only be shoving as much of the vapour that'd fit into a halfinch pipe in past the tee now with the result of the excess vapour just swirling up past the plate?

Or would the speed of the collapsing vapour suck it in at a great rate?

[rad14701]

minime, that's exactly what I had envisioned... Man, you must have a lot of spare time on your hands... Sure wish I still had a workshop right outside the door...

Are you guys talking about reducers above the plate...??? Perhaps a 3x1x1 or similar...??? I've kicked lots of ideas around over the past several months and it's been minime's developments that have gotten me to the point of actually drawing up a few... I do a lot of mental drafting while in bed waiting for sleep to come...

[minime]

Wouldn't it only be shoving as much of the vapour that'd fit into a half inch pipe in past the tee now with the result of the excess vapour just swirling up past the plate?
Or would the speed of the collapsing vapour suck it in at a great rate?

I fairly certain the smaller outlet won't hamper the process. In the other thread I did experiment with a 1" internal diameter liebig and it didn't make the slightest difference to the collection speed so I reinstalled the 1/2' liebig.
I'm not sure at which point the smaller diameter would make a difference but the collapsing vapors have to be creating some kind of void and the pressure of the rising vapor in the column is pushing also. I think once the vapor stream has been split the collapsing has already begun. A good example is the point where the temperature starts to rise. I close the valve down over half way before there's a noticeable difference in output.
I don't think my use of the 1/2 inch ball valve will have an effect as the reduction is done immediately after the valve on the other column. Reducing the outlet on the column might but I've a feeling it won't make a difference either. I actually have the column ready to go but I'm waiting on supplies. Should be here tomorrow so I can get a ferment going.

[rad14701]

I'm not sure at which point the smaller diameter would make a difference but the collapsing vapors have to be creating some kind of void and the pressure of the rising vapor in the column is pushing also. I think once the vapor stream has been split the collapsing has already begun.

Here's my twist on things... One issue that needs to be factored into the equation is the fact that once the vapor has been split off from rising, heads horizontal, and then drops through an elbow, much of the battle has been won... Having a smaller diameter condenser is actually a benefit in this configuration...

As for the reflux condenser, we need to look at that from a different perspective... With the reflux condenser located above the take-off point the vapor will require more volume to slow the upward movement... A larger volume of vapor area and condenser area is required to knock the vapor back down...

Now, would we ever get to a point where the reflux condenser is so efficient that it will rob the take-off point of any vapors...??? Very doubtful... And given the fact that minime has gone so far as to terminate the slant plate below the take-off point, he has further insured against such an occurrence...

All in all, I think this design will be very efficient and I hope minime's results are proof positive... C'mon, minime, the suspense is killing me...

[HookLine]

This thread just gets better and better.

Firstly, great idea from Absinthoman, and thanks to MM for actually trying it.

The proportion of column that is blocked by the angle plate needs to be experimented with. Going to 50% like MM has gives a fixed reflux ratio of 1:1 (when the take-off valve is wide open). It is possible that 33% blocked would be better as this gives a ratio of 2:1, which is probably the minimum needed for clean neutral.

[rad14701]

You're right, Hookline, this thread is definitely interesting... I agree that the plate needs to be played with, over time... I was wondering whether add-on plate extensions would work if they could be attached to the bottom of the main slant plate using stainless machine screws... minime, did you catch that... Hint... This method would also allow you to implement a catch lip and directional drip tube...

[HookLine]

you guys talking about reducers above the plate...???

MM and I have discussed something like this before:

VM head with reducer.jpg (18.84 KiB) Viewed 8217 times

Flare the big end of the reducer a bit to get a snug fit inside the column, forcing the vapour through the small end. Attach the reducer to the condenser.

You do not have to cut the column and solder a plate in.

An inverted reducer makes sure the reflux liquid is returned to the center region of the column.

You could put a bit of loose mesh inside the reducer 'cup' to help slow down and mix up the vapour as it hits the condenser.

[Dnderhead]

what about a making a " sleeve' with your plate on it (slide inside collum) then could be rased lowerd or remove for altering.

[HookLine]

The proportion of column that is blocked by the angle plate needs to be experimented with. Going to 50% like MM has gives a fixed reflux ratio of 1:1 (when the take-off valve is wide open). It is possible that 33% blocked would be better as this gives a ratio of 2:1, which is probably the minimum needed for clean neutral.

Thinking about that, I am wondering if we can assume that the ratio of the vapour flow down the two different paths will be the same (or very close to) the ratio of the cross sectional areas of the two vapour paths.

For example, just because the CSA ratio is 1:1 in MM's version, does that mean the vapour will split 1:1 (by volume)? Or 2:1 for a 33% blocked version?