Modernity

On 5/4/2020 at 2:08 AM, meerkat said:

For a column of 300 mm ID you definitely do not want to go for the split flow design you have shown. It is unnecessarily complex and restricts the bubbling area. I have seen single pass trays of 2 m diameter working very well, even back in the days of bubble caps.

I have never seen a downcomer with perforations at the bottom. You want the flow down the downcomer to be as unimpeded as possible, especially if the liquid is not totally clear. I would leave the bottom of the DC totally open.

The residence time is calculated as DC volume divided by volumetric flowrate. Your flowrate of 480 l/h (actually a bit less because some goes out as vapor) is equivalent to 0.000133 m3/s going down the DC and for an 80 mm ID pipe 300 mm long the volume of the DC is 0.0015 m3. If you divide m3 by m3/s the m3 cancels and you are left with seconds, so that is why it is called a residence time. Here we get 11.3 seconds - a nice safe number.

The downcomer does not run full.  Typically the level in the downcomer would be 30 to 50 % of the tray spacing. So the true time that the liquid spends in the downcomer is 3 to 5 seconds, but this is enough for the bubbles to disengage, thus avoiding vapor being carried downwards when it should be going upwards. The reason the level in the downcomer backs up is because the pressure on any tray has to be a bit higher than on the tray above it to force the vapor up through the tray and this pressure holds the liquid in the downcomer back. There is also a small pressure drop as the liquid flows under the downcomer and onto the tray.

The diagram below, from Peters and Timmerhaus, shows a variety of different tray types but I like these simple downcomers

 

Here they have shown segmental downcomers where the column shell forms the outer part of the downcomer but this is difficult to fabricate in smaller columns and it is more usual to weld a pipe or D section into the tray to achieve the all-round seal.

A very important aspect shown in this diagram is the sealing of the bottom downcomer in the base of the column. For a tray to function properly the vapor must not flow up any of the downcomers. The bottom tray seals first and then the seal is achieved in turn on each higher tray until all the DCs are sealed. Imagine the column at start-up with the bottom DC sealed by the liquid in the pot. When boiling starts in the pot the vapor cannot flow up the bottom DC and it flows up through the perforations in the first tray. The bottom of the DC from the 2nd tray will not be sealed with liquid yet and vapor will flow up this DC, as well as through the perforations of the second tray. But because the vapor flowing up through the bottom tray prevents any liquid from weeping through the holes the liquid will accumulate on the bottom tray until it can overflow the weir into the downcomer. As long as the downcomer projects above the tray more than the gap between the tray and the bottom of the DC from tray 2, when the liquid gets to a height sufficient to overflow into the downcomer it will have sealed the bottom of the next downcomer. Now all the vapor from tray 1 goes through the perforations in tray 2 and the same process allows the next downcomer to achieve its seal.

30 mm is a reasonable height for the weirs, but maybe a bit on the high side. They cannot be too low because (as explained above) they must be higher than the gap at the bottom of the downcomer so that the tray can seal the bottom of the DC. The higher the weir, the higher the liquid level will be on the tray. The higher this level the higher the efficiency of the tray, but also the more easily the tray will weep. It's all a trade-off between the competing factors.

Thank you Meerkat. That is a huge reply and a few sleepless nights to answer your questions. Thank you very much. 

22 hours ago, meerkat said:

@Modernity  I would be wary of using perforated trays if you are going to be distilling grain in.  If you are going to make the trays into a removable cassette then that could work if you need to clean them.  Maybe wait for @PeteB to post his photos and diagrams to see how he did it.  He and I discussed using very simple splash trays before he built his first column, and he came up with a very innovative way of installing the trays but I have not seen what he finally built.

If you do go with the perforated trays be generous with your downcomer sizing.  I like to allow a downcomer residence time of 10 seconds, based on the full volume of the downcomer.  If your tray spacing is around 300 mm then it would be better to install a 3” downcomer.  I also prefer D shaped downcomers.  You can make these easily by splitting a 6” pipe in half longitudinally and then welding in a plate to seal the straight part of the D.  Half a 6” pipe has double the area of a 3” pipe, but is still only 3” wide.

Some references for downcomer design also specify a maximum velocity, but this only comes into play with large hydrocarbon columns that can have +3 ft tray spacings.

The hole area (perforations) is much harder to calculate.  I found this reference that states

% Hole Area:

This is the ratio of hole area to bubbling area. The default practice is to target a hole area of 8 to 10 % of bubbling area for pressure services. The acceptable range for percentage hole area is 5 % to 15 %. However for some critical services, we can go % hole area up to 17-17.5 % provided that weeping is under control. Hole areas below 5 % are not used.

 

Despite their claim that hole areas of less than 5 % are not used I designed a column that uses 2.9 % and has been running very stably 24/7 for 33 years.  That column was a bit unusual in that it had a very high liquid to vapor ratio and I had a lot of pressure drop to play with.  For your stripper you will also have a relatively high liquid to gas ratio and I would guess that it will need 6 to 8 % open area, but that really is just a guess.

If the hole area is too small it will unnecessarily limit the capacity of the column, and if the hole area is too large the trays will weep and their separation power will be low.  Rather than taking the risk of deciding on the hole area yourself it might be better to buy trays from a supplier with a track record and who offers a guarantee. (I am not touting for business – I do not supply equipment or consulting services.)

@meerkat, great feedback thank you.

I'm processing your thoughts.

The perforated trays are a beast of the thing to get my head around.

I was considering 10% hole surface area but are more than happy to go for 6%. I can always make those holes larger if necessary later. 

I'm looking at hanging or truncated downcomers. This was the least fouling design I could come up with for gain-in distilling. 

With the down comers covering between 1/3 of the width tray area in the double downcomer configuration and 2/5's in the single downcomer configuration.

I was planning to laser cut the trays out of 4mm copper TIG welded into a stackable interlocking configuration.

The plan was to counter sink the backside of the 6mm holes (150 per tray) to reduce back pressure. 

I'm not sure how to work out your downcomer residence time of 10 seconds given the feed rate of 420-480 litres per hours. I can use the 'orifice plate in downcomer to hold a dynamic seal on the liquid in the downcomer', could you give me some guidance on what you think the surface area of the downcomer openings should be to hold the 10 second residence time?

Also, I was thinking 30mm height of the weirs. Your thoughts?

Cheers

I'm currently building a whisky column (on a budget) at the moment. The plan is to distill grain in. 

I am aiming for a feed rate of between 420-480 litres per hour. 

I had the main copper column is fabricated in 4mm copper. It's made up of two 2400mm sections. Overall it measures 5400mm / 300mm. And will hold 12-14 trays? I am aiming for a 70-73% abv spirit. 

I'm planning the trays will be perforated with 6mm? holes and 50mm? downcomers. If anyone has advice on the percentage of hole area to surface area I should be aiming for that would be helpful. 

I've just managed to find second hand a 3000mm / 110mm heat stainless steel exchanger. The tube stack is 15 x 12.5mm. I plan to counter flow the spent wort (360-420 litres per hour at 95+ degrees celsius) scavenged from the column sump via mono pump to preheat the incoming fresh wort. I'm not sure what to expect the temperature of the fresh wort to be coming out of the exchanger at but I'm guessing the heat exchanger is oversize. So if someone who is more clever than I knows how to work that out I would appreciate your math skills. 

The next on the list of things to do is to spec the size of a second steam feed heat exchanger to boast the fresh wort temperature from the heat recovery exchanger before it is delivered into the top of the column. Feel free to add any of your suggestions here as well. 

The demethanizer will be 3000mm / 100mm column packed with ceramic structured packing. 

I haven't done any drawings that are worth sharing. 

15 hours ago, stevea said:

Yeah - mibad - 95.63% by mass, the ABV azeotrope is close to 97% ABV

Thank you for clarifying the confusion. I was starting to think I was living in an alternative reality.   

I consider myself told, thank you. 

On 6/6/2019 at 6:46 PM, stevea said:

95.63%ABV is the azeotropic limit to water:etoh separation near atmospheric pressure - you can't get to literal 96%ABV that way.

 

Are you absolutely sure? I think you mean that 96.63% is the azeotropic limit. 

This is great thread. 

I've just started building out a continuous column. The stripping section is 300mm/4800mm copper tube holding 14 perforated trays. That then feeds into the factionating section which is two X 200mm/6000mm copper columns with structured packing.  There is reboilers at the bottom of stripping section and the first of the 200mm columns. 

I hope to have a feed a rate of around 1000 litres per hour. I'm still unsure of the sizing of the condensers I'll need at the various stages, there is about five in the process to make this thing work. My target is to get better than 96% abv.   

For the guys getting their head around how it all works here is the best video I've found so far. 

6 hours ago, Julius said:

How do you get the rocks and dirt off of the spuds before cooking?

Hi Julius, 

All the local spud farmer supply contracts to potato chip, fries and supermarkets. All the growers wash on-farm. Also, our local soil is a red volcanic earth that washes off well with little to no stones. 

On 9/11/2018 at 7:04 AM, Alaskan Spirits LLC said:

How did this end up working for you?  I like your idea and curious as to your outcome.  Thanks.

We have just started the build out on all the gear to do this. The key to the development of the idea was finding the right way to cook the spuds. The more I thought about how a potato distillery would work the more I realised that when the potatoes arrive in the distillery speed was the number one consideration. Nobody wants to spend 3/4 of the day processing spuds everyday of the season. 

A 20t/hour mill feed straight into a pressure cooker. Through a heat exchanger and into jacketed fermenters for further cooling for yeast pitching. 

Our pressure cooker has a high powered mixer that will move the volume around for even cooking. 

On 8/21/2018 at 10:54 AM, indyspirits said:

So, uhhhh.  Back of the napkin goes something like this... 18% of 1000kg = 180kg = 400 lbs (I cant do yield math in metric). Let's assume I can convert all of that starch to fermentable sugars. So I have 400 lbs of fermentable sugar = 18,216 gravity points which means I need about 300 gallons of water to get a starting gravity of 1.060. HOWEVER, I have no damn idea how you'd process the spuds and what that would look like in a cooker. That's a lot of water, a little fiber, a small amounts of other stuff.  Would you try to separate out the starch? Never made spud vodka.  Anyway, let's just pretend you're really good and could get 300 gallons of 7% "beer"... I think if things go your way you might get 40 gallons of 40%?  Love someone to check my math on this, it's most likely wrong.

Edit: Pure 190 proof maybe around 19 gallons (?)

 

 

I found that cooker today. 3500 litres, 125 PSI steam jacket and 50 PSI/vacuum shell. With a 500KW steam boiler we should be able to Pressure Cook 2000kgs of smashed potatoes in no time at all. 

Heading to Denver for the ADI Con and I am keen to check out a few of your local distilleries, of course.

Can anyone direct me to any distilleries that are running continuous column setups? 

Thank you in advance.

7 hours ago, admiralty said:

Save yourself some grief my friend...

 

 

Many thanks, MadMacaw.

Jeffers, head over to Amoretti.com. They will overwhelm you with flavour options and possibly make your brain explode, mine certainly did. 

We are looking around for used 5 & 10 Gallon barrels.

I found a company offering 45% discount on all their barrels. That has me worried. It sounds too good to be true? oakwoodbarrels.com What do you think?  Does anybody have experience with Oak Wood Barrel Company out of Lexington KY?

What were they like to deal with? Is it me OR does this look shonky?

5 hours ago, indyspirits said:

So, uhhhh.  Back of the napkin goes something like this... 18% of 1000kg = 180kg = 400 lbs (I cant do yield math in metric). Let's assume I can convert all of that starch to fermentable sugars. So I have 400 lbs of fermentable sugar = 18,216 gravity points which means I need about 300 gallons of water to get a starting gravity of 1.060. HOWEVER, I have no damn idea how you'd process the spuds and what that would look like in a cooker. That's a lot of water, a little fiber, a small amounts of other stuff.  Would you try to separate out the starch? Never made spud vodka.  Anyway, let's just pretend you're really good and could get 300 gallons of 7% "beer"... I think if things go your way you might get 40 gallons of 40%?  Love someone to check my math on this, it's most likely wrong.

Edit: Pure 190 proof maybe around 19 gallons (?)

 

 

Thank you Indyspirits.

My understanding is that the spuds are 80% water straight out of the ground. That's 800 litres or 211 Gallons. 

We plan to lift them from the ground and then process them directly into a potato washer/scrubber leaving the muck in the paddock. At the distillery they would be passed through a sieve plate (similar to an over sized sausage mincer). They would be cooked with or without direct steam (not sure how much extra water we will need to add yet) before enzymatic conversion. If a liquefaction enzyme is used, we are told that we can get away without adding any additional water. That would be a pretty neat idea. 

The spuds would be left in the ground for less time than an eating spud as we don't need a thick skin for transport and retail sale. As a result there would be a lot less fiber (so we are told by the growers). 

9 hours ago, Glenlyon said:

It depends on the starch content of the potatoes. European (Polish) potatoes have a high starch content, however, North American potatoes have less starch, so you need more to pounds achieve the same results. The cost of importing and using potatoes in Alaska might be a bit steep, unless you happen to have a great local source.

My mistake, I wasn't clear in my question. 

Could someone tell me what the expected (or theoretical), litres of pure alcohol, yield from 1000kgs of fresh potatoes, with 18% starch would be? 

Btw, freight is not an issue. The potatoes are growing next door.

On 10/17/2017 at 12:00 AM, Gedrick Distilling Company said:

It doesn't matter whether you use the genuine article or flakes as there is still going to be a lot of water involved. However, using your Alaskan spuds is a great marketing plus point. I am experienced in making potato vodka and I can tell you it is not simple, primarily due to the liquefaction issue. The spud is a hard taskmaster and every seven year old knows that potato and water together makes GLUE. If you need help putting together the right equipment and process for mashing and distilling a great potato vodka, I would be pleased to help you. 

Best, Gerard.  https://www.linkedin.com/in/gerard-evans-1b2b8a58/

Could someone tell me what the expected, litres of pure alcohol, yield from 1000kgs of fresh potatoes would be? 

I'm not sure if this idea creates any other issues BUT here goes. If you were to introduce a small volume of compressed air a metre back from the outlet?  The amount of airflow wouldn't need to be very great to create the effect you are after. 

Thanks a lot for your efforts HedgeBird.

One upside, the wash boil temp will not need to go over about 97C, so that will reduce the required temperature increase required down to 60C or 106F, dropping the heat up time down to 45 minutes before we take into account the lack of surface area.

Looking at the jacketed option the available pot surface area is 9.34 square meters or 100.5 square feet (sides and bottom) the heat up time is going to blow out to some what. 5 square meters of area could be achieved with 75 meters or 15 revolutions of 50mm/2 inch copper pipe around the inside of the pot

Thats for the link, I have look at steam kettles for conversion to still pots. The plan is to head down the all copper route.

I need help on calculating the surface area required for copper internal heating pipes in a 3000ltr / 800 gallon wash still design I'm working on. The pot size will be <>2000mm/1200mm - 79"/47".

I'm thinking circulating thermal oil instead of steam as the easiest option for heating the still.

My understanding is thermal oil runs at about 300C / 572F, with the oil being pumped through an open system (zero pressure) via a header tank. The heating side will be gas fired.

Agitation will be part of the design equation, any thoughts welcome.

PeteB, thank you.

We are planing a Tasmanian research trip in March, and you are on my visit list. I love what you do and look forward to talking further. I will be in contact in due course. At this point our plans are to push the go button before the middle of 2014, to be open by mid 2015.

Hi all,

Thank you for such a interesting forum. I look forward to contributing to your quality work.

Friends, Romans and Countryman,

Can you help with a bit of reverse planning? here please.

The plan has been to open a distillery primarily focusing on scotch whisky, with some gin and vodka production to round out the offering.

I have found a great stone building near the town centre, and it looks like a Scotsman built it just for me to setup a distillery in. The perfect site to pickup the passing tourist trade and with room for a tasting room and seating etc.

I want to start with a barrel (60 gal) per day capacity (4 days per week). A wash still, one spirit with the option of running a plated column for Gin and vodka production.

What I am not clear on is what size/capacity these stills need to be in relation to the required 60 gal output?

Once I know these capacities I can then work out fermentation vat dimensions, mash tun size, and then my floor area requirements and if this building will actually be suitable.

Thank you for your patients

Here's one of the ideas that came to mind when I was working on this problem; Plumb straight lengths of copper around the walls of the distillery from the mash tun to your fermentors, 1" copper with a 1 1/2" copper (or PVC) counter flow could be the go. It would then be a case of the minimum length needed for your climate. This wouldn't take up any floor space and would be very cheap to install. I was thinking to pump the cooling water through a truck radiator cooled with an electric fan and recycle to save water.

I too have been a entrepreneur my entire adult life and I have had more failures than successes, mainly because I tended to bin the failures pretty quick and keep the winners a while before selling them. But, after 25 years of making a living the hard way I have just found one of the most informative pieces of business build advice I have ever come across. I have read 100's of business, self improvement, management books but, this online FREE lecture series is gold for anyone reading this thread and thinking of going commercial. If you apply Paul's advice to the "How to build a startup" business series you will be way ready for the realities ahead. http://www.udacity.c...245/CourseRev/1

Cheers,

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