Closed Chiller Loop Water Treatment

[Josh]

Hi all,

I am using a closed loop water chiller system for my distillery and wanted to see what other folks are doing to treat the water in their closed loop system. Can anyone share what they do to keep the system from becoming a biological science experiment?

I was thinking about chlorine, but not sure about the long term effects of chlorine going through copper and stainless equipment. Any advice would be appreciated!

Cheers,

Josh

 

[Southernhighlander]

Josh,

 

I don't know much about treating water in a closed loop chiller.  However, what temp is your tap water there?  If you run the 120 to 150 F hot water from your condensers into 2 hot water holding tanks, one for mashing and the other for cleaning you will use all of the hot water and save a huge amount of money on energy costs.  With the closed loop you are cooling down 90 degrees or more while on the other end of your process you are using energy to heat water up.  It's a huge waste of energy. 

If your tap water is over 68F then instead of the closed loop you could have a chilled water tank cooled with a much smaller chiller than you would use for a closed loop.  With the chilled water tank you are cooling water just 20 degrees and then you are using the heat energy in the water for mashing and cleaning.  You are also reducing the time that it takes you to mash because you are starting with much hotter water.  On the other hand with the closed loop you are cooling down the coolant 90 degrees F or more while on the other end of the process you are heating water up.

 

Of course if you are crash cooling mash and or cooling fermenters closed loop is a better way to go.  Also some closed loop systems have ways of reclaiming heat.  I'm sorry, I know this advice comes a little late for you but it may help others who read this.  I'm sure someone will come along soon to answer your water treatment question.

[Stumpy's]

If you're not plumbed through PVC, just dump a bunch of your heads in there! It will keep your water clean, it's easier to pump than water, and will exchange heat nicely. Oh yeah....and it's basically free! Haha. We've been doing this since last October and have had some pretty good luck with it. We even installed an outdoor condensing unit off an old chiller to pump our cooling water through it from Fall>Spring. We had some pretty cold spells here this winter and the heads dropped the freezing point enough to where nothing ever froze up on us. Glycol would probably be the best solution but I was too cheap for that. P.S. that outdoor cooling unit dropped our electric bill from $1,100 per month to $350 per month.

[Josh]

Thank you Paul and Stumpy's for the responses. I like the idea of adding heads to the loop, makes sense for our existing design. We have a little PEX and some canoflex lines throughout the system, but I think that low proof alcoholic solution would work, and PEX is cheap if we need to replace it because of deterioration. We never know what to do with the heads away, so this gives them purpose and a home!

Paul, we do crash mash temps in one of your 150 gallon mash tuns, with cooling fluid in the jacket and the inner coil (twice a day on mash days) and when we run the 150 gallon on stripping runs, we need a lot of volume to keep the condenser water temperature ~60 degrees.

Thank you both again for your responses! Cheers!

 

[Southernhighlander]

Josh,

The volume of water through the condenser for that still should be between 190 and 300 gallons per stripping run.  If the input water is 48 F to 68 F with an output temp of between 130 and 145 f.  If you are using more condenser cooling water than that email me privately and we will figure out what's wrong.

 

 

[Josh]

Thanks Paul, the system works just fine, no complaints about the equipment.

[MG Thermal Consulting]

The treatment can vary from ozone, traditional chemical to glycol (glycol %needs to be 30% of else it will aid in biological growth.

I have a client who is transferring water from a couple large tanks, equalizing them if necessary, using hot water from mash cooling for heating ends and the makeup city water to temper the cold water tank to lessen the heat load on his chiller.  Much like Paul's concept.

Whenever able, I like to place a small glycol loop with an isolation to chill cold water tanks from cold night-winter air cutting down chiller usage for all winter.  I am looking to add a heat reclaim chiller to this loop as well to make hot water up to 170F, shedding off max use for boiler load.  These paybacks vary from one to 4 years. Higher temperature refrigerants will make the maximum reclaim temperature close to 190F.

Mike

[Avak]

We use a geothermal closed loop cooling system which runs through coils in a pond. The system is filled with denatured ethanol solution. I believe it is 20%. The distillery is on the Pacific Coast so there is little need for antifreeze effect. The pond seldom even gets a skiff of ice in winter.

 

Avak

[MG Thermal Consulting]

I hope your electrical is explosion proof, a word to the wise.

 

[Josh]

16 hours ago, Avak said:

We use a geothermal closed loop cooling system which runs through coils in a pond. The system is filled with denatured ethanol solution. I believe it is 20%. The distillery is on the Pacific Coast so there is little need for antifreeze effect. The pond seldom even gets a skiff of ice in winter.

 

Avak

Thanks for sharing this - using a pond as a heat exchanger is novel for sure! Not many people can say that as part of their process. Denatured alcohol seems like a consistent theme here. I also like the ozone treatment idea, but I would have to think about how I'd do that practically speaking.

MG - appreciate your point on explosion proof. We bought a rite temp water chiller from you a couple years ago, it's not explosion proof, so the level of alcohol is important to consider from that perspective.

Appreciate all the responses!

[Avak]

Re: the 20% ethanol geothermal system. Explosion is not an issue since the pumps and controls are in the mechanical room. Only cooling lines enter the (explosion proof) distillery area. A coolant spill is treated the same as a spill of product. The system is only serviced by a commercial geothermal company.

The system works so well there is no heat pump, only heat exchange coils in the pond. If cooling requirements increase with production, a heat pump could be added.

Avak

 

[MG Thermal Consulting]

I have augmented a few set up like you describe, usually in most of the USA, the ground temp is 55F as far as design goes. You can run a still with 55F but rarely can you get mash cooled with that temperature, so if you need a booster chiller, you are back to buying a chiller and heat exchanger to do that, and you'll need colder than 45F to overcome the bad heat transfer of the alcohol if you use that as a cooling medium.

The further I go North, I offer dry coolers and heat exchangers for winter use, to save utilities that way, along with a generous reservoir tank which is normally cheaper than a geothermal set up.  Most people don't want to have the worry in any event of a heat transfer leak underground. EPA becomes a little vocal about it. How many gallons is your complete alcohol charge that you use for heat transfer, just for giggles?

[Avak]

On 7/18/2018 at 10:15 PM, MG Thermal Consulting said:

I have augmented a few set up like you describe, usually in most of the USA, the ground temp is 55F as far as design goes. You can run a still with 55F but rarely can you get mash cooled with that temperature, so if you need a booster chiller, you are back to buying a chiller and heat exchanger to do that, and you'll need colder than 45F to overcome the bad heat transfer of the alcohol if you use that as a cooling medium.

The further I go North, I offer dry coolers and heat exchangers for winter use, to save utilities that way, along with a generous reservoir tank which is normally cheaper than a geothermal set up.  Most people don't want to have the worry in any event of a heat transfer leak underground. EPA becomes a little vocal about it. How many gallons is your complete alcohol charge that you use for heat transfer, just for giggles?

The specific heat of 20% ethanol is roughly 10% lower than water. Not so bad. I think the pond is a better heat dump than the ground, but thermodynamics was never my strong suit. The waste heat is also used for in-floor heating in the office and lab areas.

With the present counterflow cooler, the system works well if the mash pump speed is kept slow. We have tried recirculating the mash through  the cooler at higher flow rate, but the total cooling time was the same... about 15 minutes. I never bothered measuring temperatures of anything except the mash, because the system worked perfectly from day 1, even in the summer. Plug and play. 

Avak

[MG Thermal Consulting]

If you keep your pond at 55F or lower, then I would agree but I don't know the volume of the pond or the temp.  I would say in most places it wouldn't work year round, only as a part year solution.  Are you pumping ethanol on both sides of the htx or are you pulling pond water directly into the htx?

If you are pulling it directly, how do you keep the htx from being fouled, a large filter?