cooling water temperature spread

[virtuoso]

I remember once learning about the temperature of the incoming cooling water and the out going watershould be a specific degree spread to get the best spirit quality i seem to remember it was around 22 degrees. Can anyone help remind me what that spread is suposed to be.

steve ross

[Falling Rock]

There are three posts here about coolant and distillate temp within a few hours and none of the same people involved, hmmm....

Safety says that the coolant outflow from the PC should run between 125-140 deg F (test your PC) to assure all vapor being condensed.

Water/energy conservation says maximize water temp to save on water and/or power circulating the water. Again "supercooling" (anything colder than needed for 100% reflux or Product Condenser) the water in a delpheg or reflux coil is another energy waste.

One of the other topics has to do with product quality and refinement. I want to hear comments on that!

[MG Thermal Consulting]

Much of this depends on the design of the condenser. I have seen a large spread of water GPM requirements for the same size stills tells me one thing, the outgoing water will vary as widely.

80 to 100F is more common for recirculated water systems, meaning temperature incoming is lower or the flow is greater than for city water.

[Roger]

My stills have devices like these in the condenser water lines, which allow you to control the temperature of the water based on the probe mounted near the condenser outlet (mine are in the top of the condensers. The valves operate between apx. 80 deg and 200, and you adjust that with what is essentially spring pressure to set your desired "ending" outflow water temperature and subsequent distillate temp.

Because you are sensing the ending temperature, it doesn't matter what temperature water goes in at, because the valves open and close as needed to adjust for your desired output temp. My stills were built specifically for brandy, and they were set up to run in a single run at 160 proof .

http://www.ebay.com/itm/Danfoss-Thermostatic-Water-Valve-AVTA-25-/131139817684?pt=LH_DefaultDomain_0&hash=item1e888ad0d4

[Falling Rock]

Beautiful and practical setup Roger...

[Natrat]

Danfoss AVTA valves are a mainstay of the industry. They are very reliable.

However, they are not extremely accurate...which has to do with the low resolution scale on them, as well as the effect that flowing water has on them (once the water starts moving, they require more spring pressure to shut than the spring pressure that was holding them closed)

They aren't cheap, either. Many of us end up using a PID temperature controller and a solenoid valve, instead. More accurate...and actually cheaper.

[Bier Distillery]

Anyone selling simple/cheap solenoid/PID solutions?

[Natrat]

Go to Auberins.com and get a triclamp RTD ($40) an SYL1512 PID ($38), and buy a relay from ebay for $30. That's for water control. Add $150 for a steam control solenoid.

I'm assuming you have some AC/DC knowledge...depending on your power source and application you may need to rig up a power supply, relay, etc. But that's most of it. Another (more expensive) solution is to use a Johnson A419 controller ($75) or a Solo SL4824 ($90) or the Love, Red Lion, Omron...there are bazillions of PID manufacturers. The only one I will tell you to stay away from is the one called a Rex...generally you see them for about $15, and they are utter junk.

Auber makes a quality instrument for a reasonable price. I prefer the Siemens or Fuji PIDs (partially because I am so familiar with them) because they can survive vibration and impact so well, but for a mounted panel, the Auber or Love is a great choice. You can use them for controlling heating OR cooling. If you haven't done this before, prepare for the headache of figuring out your wiring and programming, but once you've done it, it's easy. WAY easier than programming a DVR!

That's as compared to a Danfoss AVTA for $350 (dealer) or $130 (ebay).

[MG Thermal Consulting]

If you have a closed loop cooling set-up, another way to go on the process pump (not your chiller pump) is to run it with VFD via your temp controller, control panel package, throttling the flow without valves and saving electric.

[jerrysun2014]

Danfoss AVTA valves are a mainstay of the industry. They are very reliable.

However, they are not extremely accurate...which has to do with the low resolution scale on them, as well as the effect that flowing water has on them (once the water starts moving, they require more spring pressure to shut than the spring pressure that was holding them closed)

They aren't cheap, either. Many of us end up using a PID temperature controller and a solenoid valve, instead. More accurate...and actually cheaper.

why will be more accurate?

[Natrat]

jerrysun2014, as I said in my post above, the AVTA relies on spring pressure to close the valve, and an enclosed gas expansion to open it, so that the range is dependent on the temper of the spring. With a digital controller, you can set your hysterisis and have it be as accurate as you desire.

[Silk City Distillers]

Thanks for the info on that Danfoss Valve - something to be said for the simplicity of the approach.

Natrat - are you simply just controlling the pump on/off with the relay, or are you using some sort of proportional control valve?

Last question I promise on the steam valve - any suggestions on a controllable proportional valve? Was looking at something like a Belimo LF24-MFT.

[Natrat]

jamesbednar, typically, your flow (via pump or city water) is on all the time, and the controller (or AVTA) simply opens or closes as needed...solenoids are an easy thing to control via relay. And that goes for your steam as well...a proportional steam valve (usually a pilot valve system) costs as much as a new pump! A steam solenoid is the way to go, installed between the shutoff and the jacket. I like to put the solenoid between two shutoffs, and I will usually put a bypass in as well, because I like flexibility and repairability during my runs.

The beauty of this is that using solenoids works with electric systems and bain marie as well...only the relay is hitting the elements on and off instead of the steam valve open and closed. This way you can get away with a much cheaper PID than is needed to operate a proportional valve.

There are proportional valves, of course, but you are looking at about $2800 for a pneumatic valve, $3100 for a pilot-proportional-steam, and tack on another $400 for a stepper motor valve. There are some that are cheaper, but I wouldn't trust them to run my still! The reason they are so expensive is because of the gearbox that allows them to have enough mechanical advantage to actually shut off a flow of steam (since they are typically butterfly valves)

The valve actuator you referenced is actually a damper motor, and while it might be capable of closing a LP steam valve, I don't like trusting to things that are clamped on! It's torque spec is only 95 in-lbs (which is about 1/4 of what a good cordless drill is capable of). I'm not saying it won't work...it might...but I think spending an extra $40 on a good solenoid is far easier. Because all of our operations are buffered by the physical properties of the fluids we are working with, the on/off action of a solenoid isn't as much of a burden. Also, because our steam is not appreciably hotter than what we are heating, proportional control is contraindicated. Now, if our heat transfer fluid was operating at 2x or more of our process fluid, proportional would be a good choice.