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Non Contact Cooling Water. What To Do?

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So, I was wondering what the rest of you out there do with your cooling water coming off your still. We are going through almost 1000 gallons a day. We operate in a drought-prone area, and we just hate seeing the water go down the drain. Any good ideas on heat exchangers or reuse of this water? Anyway to close the loop in the system and have it recycle back as cooling water?

We have been using it for irrigation, but there is only so many plants we can water without drowning them.

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So, I was wondering what the rest of you out there do with your cooling water coming off your still. We are going through almost 1000 gallons a day. We operate in a drought-prone area, and we just hate seeing the water go down the drain. Any good ideas on heat exchangers or reuse of this water? Anyway to close the loop in the system and have it recycle back as cooling water?

We have been using it for irrigation, but there is only so many plants we can water without drowning them.

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Just get a reservoir tank and a chiller. Use the chiller to cool the reservoir water and pump it to your still on a loop. It might heat over the course of the day and the chiller can then cool it down overnight.

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I can send you a schematic of a distillery with chiller, dry circuit cooler (for winter-it's up North)which provide the cooling for the indoor reservoir which in turn feeds the condenser and mash exchanger. The chiller was going to be indoors too, but space was not available. I provided the cooling equipment and the use of the dry cooler will cut the chiller use to near zero all winter. Email me and I can send you over the schematic with pictures of the cooling equipment.

Mike Gronski

770-995-4066

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Fugenator,

I implemented a system at a distillery in a similarly drought-prone area that collected the hot condenser water in a reservoir, then recycled it back into a cold water reservoir through a heat exchanger while the still was being filled with the next charge. This system greatly reduced heat up time, saved energy on heating, saved energy on cooling, and, most importantly, saved LOTS of water. It was rarely necessary to dump any water at all.

In order to keep the water relatively fresh, I installed an ozonator on the cold water reservoir (like one you'd install in a residential pool). The hot condenser water reservoir was also extremely handy for cleaning tanks, sealing barrels, etc.

If you'd like any more details, let me know.

Nick

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Nick,

I'd love more info on that. I use a bunch of water and I'd like to significantly cut down on that usage. We have a 400 gallon and a 175 gallon still. I've been thinking of going to a cooling tower, but I'm not sure that's the best solution.

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Nick,

I follow what you are doing on the heat reclaim side, but I don't follow you how this can reduce the cooling unless your cold water reservoir is inside a blast cooler.

You can reduce the utility, I agree, on the heat side but your cold condenser water has to come from somewhere, so the refrigeration chiller replaces the city water.

John,

Cooling towers can only cool water to about 85F in the summer because the cooling is based on wet bulb, which is probably around 76F where you are. the cooling tower also uses about 2-5% of the water sprayed over the fill, so you still have a utility bill for that along with filtration of the water out of the tower, which is why I recommend dry coolers integrated to a chiller (or city water loop for the summer)- you already have the closed loop (glycol/water mix) that is pumped through the heat exchanger to make your cooling. Either method you will need summer booster cooling, but the dry circuit is cleaner and you won't have to worry about winter freeze on the cooling tower.

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Nick,

I follow what you are doing on the heat reclaim side, but I don't follow you how this can reduce the cooling unless your cold water reservoir is inside a blast cooler.

You can reduce the utility, I agree, on the heat side but your cold condenser water has to come from somewhere, so the refrigeration chiller replaces the city water...

The cooling is reduced because heat is removed from the hot condenser water on its way back to the cold liquor tank where the cooled condenser water is re-introduced into the distillation process. It's a little difficult to explain, but let's give a shot, shall we: (all temps in F)

Start of first batch:

-Hot liquor tank - empty

-Cold liquor tank - full of 50 deg H2O

-Pot Still - full of 35 deg wash

End of first batch:

-Hot liquor tank - 3/4 full of 170 deg H2O

-Cold liquor tank - 1/2 full of 50 deg H2O

-Pot Still - empty

At this point, the hot liquor exchanges its heat with the wash as the pot still is being filled with the next batch, and gets recycled back into the cold liquor tank...

Start of 2nd batch:

-Hot liquor tank - empty

-Cold liquor tank - full of 65 deg H2O

-Pot Still - full of 150 deg wash

As you can see, after the initial heat up, much of the heat and all of the water is saved. The savings on cooling can be looked at as the difference between cooling down your condenser water reservoir from 170 deg to 50 deg and cooling it down from 65 deg to 50 deg (well, I guess because of the buffer of water left over in the tank the first number would actually be more around 110 or something, but you get the idea). And there is a glycol chiller that chills the cold liquor tank, if that's not already apparent. With my chiller, I had no trouble knocking the temp down the remaining 15 degrees in the time it took to get the next distillation underway.

Obviously, these specific numbers are dependent on the particular equipment that I was using (such as an oversized condenser that was extremely efficient), and the same process run on different equipment would inevitably be different, but this is just an example of one way that it was done. I bet the process could be made even more efficient with some tweaks...

Hope that helps!

Nick

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Ok, gotcha, I figured you had to have some kind of a cold glycol loop in there somewhere.

I think it's a function of the batch vs linear cooling profile of the chiller. Curious, what size chiller do you have?

What spread is your isolation exchanger sized for (difference between output water and the input cold glycol)? I try to size mine for 5 degrees, that way I don't pay as much for KW on the chiller vs a little more expensive exchanger.

Good way to save Btu's on the heat recovery.

Up North, I try to extend it as much as I can by the drycooler which can get most of the cooling when you are below freezing and if you're not doing mash cooling, the cold water tank can be much smaller, the mash cooling being the gorilla behind the still that wants to grab ya.

If I can, I try to put the chiller indoors (or use a split system with refrigeration condenser outside) so I can eliminate the glycol except where I have a drycooler. With casters on the chiller, you can move the chiller outdoors and the discharge air doesn't heat up the process area- real convenient for small units.

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Base on what usage you have there, your continuous load is about 42,000 Btu/hr (3.5 ton chiller). I have a used 3 ton (460/3/60) but can get you a new one shipped in two weeks or depending where you are located, a drycooler will get you most or all of the way there with a heat exchanger loop and tank. The 5 to 10 ton drycooler I use will cost you $2,500 or a 4 ton chiller another $7,750. Now if you can pipe the drycooler with a heat exchanger on the exit of the still condenser, that will work on the highest temp of the condenser water which would then go to a poly reservoir tank from where I have a 2 ton chiller to work on the water tank to get it to 50F. I have two used 2 ton chillers, 230/1/60, both priced at $5,000. Chiller and drycooler have their own circulator pumps. You would still need to buy the in-line glycol to condenser water exchanger.

A couple ways to skin the cat.

The drycooler has 1 HP pump and 1/2 HP fan motor and the 2 HP chiller also has 1/2 HP fan motor, 1 HP pump besides the 2 HP refrigerant compressor, max HP would be 5 HP and minimum 2.5 HP (both pumps need to run). You can do the math for your run hours KWh vs the 1,000 gal/day cost plus sewer.

Normally the closed loop payback is less than two years, but most of the time less than a year.

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...Curious, what size chiller do you have?...

If I remember correctly (it was a while ago I guess) I was running a 10 ton full-package chiller. The CLT was 2000 gallons.

...What spread is your isolation exchanger sized for (difference between output water and the input cold glycol)?...

Not sure what you mean here. I did most of my sizing without the aid of an engineer or fancy schmancy concepts. I just sort of went with units sized like I thought they should be, based on experience. If you could be more specific, I'd be happy to attempt to answer, though.

By the way, love the air-cooled heat exchanger rather than cooling tower idea. More distillers, especially those up north, should implement that.

Nick

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You must have a lot of space!! Sometimes space is a real problem and new distilleries believe that reservoirs are unnessesary until they get the shock that they can't crash cool or realize just how much water is going down the drain.

The distiller has to be pretty savvy to think through and execute a utility (water and power) saving program to the extent you have.

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Mike,

We are a start up distillery that has a couple hurdles as far as chilling mash and condensers. I would like to discuss these with you if possible. Example no easily available 3 phase and we are on well and septic for waste. We do however have a fair amount of room for equipment. it might be easier to email me @ Blake@silverbackspirits.com or I could call you if that works for you.

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I came up with a similar cold liquor recirculation loop in our new distillery. The idea was to pump cold water (32 degrees) from one cold tank through the dephlegmator and condenser and return it to the other tank. During our first run, Sherman (who was on site to install the Vendome touchscreen) suggested that we return the water back to the original cold tank instead of the empty tank. Town water is T'd into the system, so we figured that if the water from the first tank got too hot, we could run town water through the dephlegmator/ condenser and return it to the other (empty) tank to finish the run. We didn't need to. One tank was plenty to run a single batch in a day and the chiller cooled down the water back to 32 overnight.

So we have a 2 square 550 gallon tanks (that are jacketed on 3 sides). Our still is a Vendome 250 gallon column still with 4 bubble caps. A half hp pump and a small chiller complete the system. You just need to loop both tanks from the supply side (with appropriate isolation valves) to the pump through the dephlegmator/ condenser and return it to the top of both tanks (again w/ isolation valves). I have run the still 20 times and have only used the original 550 gallons of water. The second tank is still empty. The system has worked better than I could've imagined. I hope this helps.

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Basically what I recommend, David. But if you have a system like yours, I'd be looking at about one 500 gal reservoir and a 4 HP chiller.

For those up North, I quote them an optional winter glycol cooler (has its own circulator pump) and an indoor isolation exchanger for another $3,100 an you can cut the winter HP used from 5 1/2 HP (chiller compr, fan & pump) to 1 1/2 HP (wintercooler fan & pump) in this example. May not be much with a small system, but if you do mash cooling and you have a 10 ton chiller, the wintercooler (a larger htx is needed) saves quite a bit more HP.

Another factor going to two tanks and not one is that the chiller temp is lower 32F vs 50F which costs more in Kw/ton of refrigeration. Of course, it depends on the amount of hrs the chillers are actually running and the efficiency (my 50F 4HP would need 6 or 7 HP to get to 32F).

There are always several ways to skin the cat, but most are similar in that they use the flywheel effect of a storage tank.

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I have a 2500 gallon reservoir and 500 feet of PEX buried 4' deep that the water passes through before returning to the tank. I use the earth as a heatsink. It knocks the water temp down to about 70 degrees before returning to the tank.

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I love it! A geothermal cooling loop! (I used to install geothermal and hydronic floor systems)

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Does anyone have a document describes a cooling tower as an approved cooling method for non-contact cooling water?  Something that would satisfy an inspector that doesn't have much experience?

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"process water" is your city water with treatment (making it non-potable).

A cooling tower requires continuous treatment because water is continually being used and made up due to evaporation.

Mike

 

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Exactly what sort of treatment?  Do you have documentation that I might be able to share to show an inspector that a cooling tower is safe?

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Your water treatment company that you are using for your potable process water would know what chemicals need to be added to make the tower sump safe from such things as Legionnaires bacteria that make a non-contact process water safe.

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