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Mash tun/Boil Kettle Design


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Hi all, I have trolled through the forum looking for answers to our questions and can't seem to find any. We are partnering with a local brewery equipment manufacturer to have our mash tun made. They do excellent work (http://rockymountainvessels.com/) but have not done any work for the distilling industry. They are willing to work with us to get what we need and will be matching the price of any U.S. manufactured equipment, so its a great deal for both of us. Problem is they haven't dealt with a distiller before and we haven't opened our distillery yet, so all of our production requirements are coming from other distillers and/or trying to scale up what we've been messing with in the garage. So far we have them working on a design using a steam jacketed bottom for heating, and water or glycol jacketed sides for cooling. The heating and cooling times get better if we focus on glycol and if we do direct steam injection (apparently there are two types of direct injection being used in the industry and the newer method is more efficient and less noisy...not sure), but the costs go up. Anyone have insight into the various heating and cooling technologies and the pros and cons? Is it worth the cost to invest in direct injection and glycol when we are starting out?

Like I said, the heating and cooling we are pretty sure we have pinned down, but the remaining questions are:

1. What is the make and model of the agitator/motor being used by other manufacturers? What are its specs/features, including HP, VFD or not, operating speed (RPM)? What is the design/shape of mixer/paddles (1 or 2, what angle)?

2. Is it necessary to insulate the mashtun or just have it steam and glycol jacketed?

3. Is a false bottom something that is worth having them make? We'd like the ability to lauter, more like a traditional scottish approach, but again, is it worth it?

If anyone has the actual design/drawings of their system with the attached notes and key to all the numbered parts that would be amazing if you are willing to share (I have a bunch of schematics that have call-outs for all the parts on the system but then they never come with the sheet to tell you the specs on part A9 or whatever). Thanks for your input.

 

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We went the same route. We have a local fab shop do all of our stainless work, from a few feet of pipe up to 7000 gallon tanks. 

We decided on direct steam injection over a jacket and it lowered the price a little bit. We have some Venturi style nozzles, they are loud, but not too loud, good and fast heat up. We went back and forth on direct inject versus jacket, and settled on direct inject. It works fine, but in hindsight the steam jacket probably would have been nicer. We have to deal with occasionally plugged nozzles, food grade boiler treatment chemicals (we use steam for sanitation of equipment and swelling barrels so we needed this anyway) plus the cleaning of the manifold.

We had the fab shop put in 'pegs' around the bottom designed to hold some U channels that can hold wedgwire screens if we choose to go that route, but I think it will be kind of tricky with the direct steam heat to use them. Whether or not is worth it is up to you and what you are going to make. We haven't even thought about having the screens built yet. But if you want to do lautering I'd definitely recommend a steam jacket over DSI.

We insulated the mash cooker, it's nice to have in case someone leans on it, and it holds heat really well, but you can get away without it. We do an external exchanger for cooling so we can use it for other things, but a built in jacket for cooling would be nice. 

Per the agitator i want to say ours is 3 HP on a 500 gallon, our fab shop had it quoted by a supplier for the application.

If I had to do it over I think I'd drop the side man-way, insulation and lauter pegs, and go with steam jacket over DSI, plus a cooling jacket. That being said, what we have works amazingly well, we will do 2 cooks in 7 hours tomorrow including setup and tear down, and I don't think jackets would give me that speed.

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We use a single 3/4"TLA Eductor in a 600 gallon tank (http://www.nciweb.net/eductor_tla_heater.htm) for Direct Steam Injection.  It's pretty loud, but the heat up time is great.  Costs should go DOWN with DSI - significantly less effort than a jacket - unless the heating jacket just gets used for cooling and there isn't any less labor/material.

We did it because we converted a jacketed/insulated dairy tank into a mash tun - and we wanted to use the single jacket for cooling.  Both our still and mash tuns are insulated - absolutely a benefit to insulation, and not just safety, but efficiency and reduced heat up time.

The agitator design will need to be specific to the tank geometry and density - motor size, gearing, blade size, shaft length.  We have a geared down 1hp agitator (90rpm) on a 600g tank, and I'd like a bigger/faster agitator.

Your chiller sizing will have more to say about cool down times than water vs glycol - if that is what you are asking.  Glycol or not should be irrelevant to the jacket design.

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Tom and Silk,

Thank you both for the info. I will forward on to our local manufacturer and see what they say. Its tough trying to answer engineering questions when we haven't done this before and if it didn't cost thousands of dollars to get something you may not like I would say the equipment purchasing process has been exciting. Our hope using a local fabricator is that if we have other stainless steel issues or any welding on the still, etc. that needs to be done they would be willing to help, and more knowledgeable than just getting a local welder off the street.

Dave

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  • 3 weeks later...

Guys,

Can either of you explain how you account for the addition of the water vapor into your recipe by using DSI? I am sure if you know the rate at which the steam is being injected and the amount of water contained in the steam, you should be able to figure out how much added water you have due to heating...or is it negligible? Also since the steam is contacting the mash, my understanding is you have to use culinary steam, which means chemical additions. Does adding these chemicals affect flavor or negatively impact fermentation/yeast vitality? The rapid heat up time sounds awesome, so I like that about the DSI system, but the issues of added water and the potential impact of the chemicals to make the steam "food grade" worry me a bit.

- Dave

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For us we see about 5 gallons of water added (in the form of steam), per 10 degrees we need to heat for 500 gallons finished volume. We subtract the added water to compensate to keep volume consistent.

The formula I was given is something like this: (Total finished volume * 8.34 * target SG)  * (Target temp - Start Temp)/1000 = Pounds of steam.

Pounds of steam/8.34 ~ gallons of water added in the form of steam.

Real life example: here are some numbers for a typical cook. 380 gallons at 100F heated to 185F, with the corn adding malt and rye or wheat on the way down nets us a total of 500 gallons of total volume +/- 10 gallons. We typically double cook into one fermentor, so we shoot slightly lower on water on the first cook, and then add the difference to the second. If the water we started with is 130F, we would do 15 more gallons of water to compensate for less steam added.

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There are Spirax Sarco filters that you can use for sanitary steam, or you can use a steam boiler that is stainless and produces sanitary steam.  

Most of the big distilleries that direct inject steam into their large continuous columns stills, do not use sanitary steam.  They just direct inject from their ferrous metal boilers and they have been doing it that way for many decades. They do not seem to have any flavor issues from it.  Personally, I would probably go with filters or a boiler that produces sanitary steam.  If anyone is looking for a DSI mash tun just, let me know and we will get you a quote.  417-778-6100

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Roughly, very roughly.  For every 9,500 BTU added, you'll add a gallon of water.  Remember, simply, BTU is raising the temperature of 1 pound of water by 1 degree Fahrenheit.  So, let's say you had 100 gallons of water (834 pounds) and you wanted to raise it by 50 degrees, you would need 834*50 = 41,700 BTU Required.  That would take 41,700/9,500 = 4.4 gallons of total water/steam condensate added to get there, for a total volume of 104.4 gallons.  Again, very roughly - this doesn't take into account the net change in total temperature as a result of the additional water volume, but that should be minor.  It also assumes 100% efficiency.

Culinary steam does have a specific definition in the FDA, which is easy to meet if you use *NO* boiler additives or chemicals, and you can filter the steam such that 95% of particles 2 micron and larger are removed from the steam.  We use the Spirax Sarco filter that @Southernhighlander mentions.

 

 

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If you are willing to lauter all of your washes, you have to use predominantly malted barley in every mash, which drives your material cost up somewhat, but simplifies a lot of the other steps quite a bit.  If mash in with water that is hot enough, you wouldn't have to raise the temperature at all, or just enough to make the lautering flow easier, can use a plate and frame heat exchanger to quickly cool the wort down while transferring to the fermenter, and not have to deal with thick grain slurries in all your downstream processes.  And the mash tun is then much closer to what your manufacturer is used to making for brewery use.

Also, if you are mashing or distilling almost every day, you can refill the hot water tank with the heat exchanger and condenser cooling water, so you are constantly topping it up with hot water for mashing and cleaning. 

What batch sizes are you looking for?

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I have had good luck using a mash tun built with two steam jackets and two cooling jackets. To keep costs down, you can use a mash pump to agitate. I like DSI, but I prefer having a steam trap and conventional steam system. I don't find heat loss on uninsulated vessels to be expensive, but I hate burning myself and I also hate dripping sweat into my mash, so I vote for insulating your vessel. Using water in the cooling jackets means I can recapture some heat into my next mash water. Technically, I could probably run cooling water through the steam jackets, but I don't like shocking the dimple jacket that much.

On a 400 gallon batch, using diaphragm pump agitator, heat up to 185 F is about 32 min at full blast (Delta T of 125 F) and coolout to yeast pitch (at 92 F) is 50 minutes. That particular mash tun was $12500 delivered, but it did have some issues. The lauter screens were useless, but aren't used anyway.

Most fab shops that can do tanks for the oil industry can build steam jackets.

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Thanks all for the updates. It looks like we are going to ditch the DSI in favor of the jackets. The temp calculations we are getting from the manufacturer suggest we might be better adding more steam jacketed surface for heating and just using an external heat exchanger and pump to crash cool. The DSI quotes from 3 boiler manufactures all are about 25% more expensive than a standard setup, so that is driving the decision.

- David

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