Water Cooler

jacksonbrown

I think HD has had way too many years of people blindly following the guy in front. The smart guys that were capable of thinking for themselves either walked or were pushed out of there a long time ago. It's pretty stale in its current, sorry state.

@vooharmy said: Will something like described work better than an old AC?

What you're suggesting is exactly the samething.
To find out if it will work better (or at all) you have two options. Look at the figures and do the math
or
Have a crack and arse your way through.

There are heaps of tricks you can do to change how well it works.
How much total power are you tring to remove? It gets a bit complicated dipending if it's a cm or VM and single pass vs recirc but if you decrease the flow rate the delta T should go up so more efficiency.
Even in the high flow recirc systems the actual coolant flow rate is very low, effectively being dosed into the recirc loop.
The lowest risk approach is to just throw a half brick at it and guarantee that it'll work.
What I mean by that is when a heat exchanger is to small you have a problem, when it is too large it just works a bit better.
Just over size it and you'll be fine.

If the air temp is too hot you can even add an evaporative component for the price of a sack of potatoes.

@grim said: Kapea - Ahh, the elusive air cooled still.

Mines an air cooled still, it's just indirect v direct.
I'm only using enough water to keep it flooded.

Kapea

@grim said: Kapea - Ahh, the elusive air cooled still.

Nah, I'm just making the point that an air cooled heat exchanger only needs to bring the condenser's cooling water to a temperature a few degrees cooler than the phase change temp of the vapor you're condensing - that of pure ethanol being the lowest temperature you need to achieve. As Harry rightly points out, if your ambient air is only 10-15 degrees cooler than that you'll be cooking for sure...

vooharmy

@Jacksonbrown Have a crack and arse your way through.

Pretty accurate description of what is going to happen =)

jacksonbrown

@punkin said: On HD it was considered unsafe to even mention using a radiator for coolant water for the possibility that the condenser could spring a leak

You could pop a hose on any system and end up with a room full of vapour.
I have a flow swith on the return to the buffer tank.

As long as it's down stream of the condensers you'll know they got water.
Mine switches a relay that cuts the signal to the SSR's and the power to the pump and fan but just putting a buzzer on it would be pretty easy.
Can be had off eBay for under 50 bucks.

TheMechWarrior

Is this the one you have @jacksonbrown?

jacksonbrown

No, mines a SI5000. I guess that one has a relay built in. I think mine is just a transistor (DC pnp??) that I hooked up to a 3PDT relay that turns a few other things off or on. They have all sorts of weird an wonderful options if you have a special need but if you're buying second hand you miss out on most of the range. How familiar are you with instrument suppliers? There a few others of note.

If your buying new shoot me a PM.

jacksonbrown

Just an update.
Pretty happy with how this thing is working but there's a little quirk with the fan I got.
On start up it judders a bit while it decides what direction to turn then takes off.
This is normal for the design but a few times it has go the other direction.
So instead of pulling air through the entire coil (creating some negative pressure in the box) it is actually just blowing on a small section of the coil.
The efficiency drops right off and the cooling water climbs to 10° or 15°C above ambient.
It's not such a big deal for me as I don't ever push things to the limit but it is a bit annoying and something to be mindful of.
If the power is cut for what ever reason (low flow) then when it comes back on I have to double check the direction.
My temp sensors have a switch built in so I might add a fail safe in the future (or upgrade the fan).

CothermanDistilling

can you measure l/min and temp drop? that will give us a good idea of your cooling capacity..

then you can take some math out of the spreadsheet (XLSX) I introduced a while back in this thread..

CothermanDistilling

^^^ and I say the above, cause at a minimum, I want that exact same looking thing outside my building doing pre-cooling of RC water from 165 down to 100-120F at about 4L/min...

jacksonbrown

The more you can stretch out the difference between the water temp and ambient the better.
Low flow, supper hot will work better than high flow, luke warm even if it the same power rate going into both.
You're probably aware of that but I'll try to get some numbers on both for you (and 4L/min too).

jacksonbrown

Got some numbers for you. Sorry, the highest flow rate the crappy Chugger could handle was 2.2L/min.

First three columns are the raw data. L/min and HEX power were calculated.

TTin (°C)               TTout (°C)              FT (gal/min)            L/min           HEX Power kW
31.3                    78.2                    0.135                   0.511           1.671734584
30.8                    76.4                    0.135                   0.511           1.625396525
33.7                    44.5                    0.585                   2.214           1.668170118
34.0                    45.0                    0.585                   2.214           1.699062157
32.2                    52.8                    0.300                   1.136           1.631733354
29.6                    90.8                    0.100                   0.379           1.615891282
28.3                    91.2                    0.095                   0.360           1.577738294
33.5                    44.5                    0.575                   2.177           1.670018359

Ambient was around 22° - 23° and the vapour temp would have been climbing from around 91° to 98° over those figures (they're in order).
The second and third last one were giving pretty warm distillate so that's where that extra power went.
The heating element was 2.2kW and it took 25% to 30% power to get the juice flowing, so around 550 to 660 Watt losses in this set up.
After start up it was on 100% all the time so 2.2kW - 0.6kW = 1.6kW
The condenser power calc in the last column confirms this (4.185 * (L/min) * (∆T)/60).
Balance tank only has about 5L but it still takes a while for the temps to stabilise which is the main reason for some of the discrepancies.

As far as outside units go mine on the small side. You can get them 2 or 3 times bigger and if you were still falling short just get a few and stage them but if get that flow rate right down and you're willing to let TTin climb a bit then mine could do well over double what I gave it today, probably triple if you live somewhere cold.

You can see above that the hotter the water going in the cooler the water coming out (for a given power).

grim

Actually, you have a really nice relationship in those data points, you've also found some data around a pretty important number, which is going to be the lowest Tin - which appears to be 6-7C over ambient - that's the best possible #.

grim

I remember seeing somewhere the theoretical best case being about 5 degrees C between ambient and output temperature. If you need anything more, you need to go to a cooling tower or add water sprayers (which changes the baseline to the wet bulb temp vs. ambient).

dad

No matter how much I like automation, I have a distrust of it!

I have a question and it's not meant to be a grenade.

Most of the cooling systems I see here are built on availability of pumps and power.

If you're in the middle of a run and power fails, will you have enough water/cooling to condense until vapor stops?

I've planned for a water supply system above the still. A min 500 gallons, to get me either through a run or to shut down if the electric failed. I've only seen one other system where the water supply tank was above the still.

Are we figuring in a plan for a power failure?

Unsensibel

For me, the answer is easy:

With electrical heating, no power, no vapor, no need for cooling

CothermanDistilling

@Unsensibel said: For me, the answer is easy:

With electrical heating, no power, no vapor, no need for cooling

I think he was wondering if the built up energy could overpower the existing cooling...

IMHO, unless you had a pressure vessel storing energy, the answer is no, you will be perfectly fine...

dad

Well, my worst case scenario...

500+liter ban marie, electric elements, ten minutes after heatup and power failure.

With no ban marie or steam jacketed experience, I believe the still will make vapor for another ~10 minutes.

An immersed element still will stop making vapor in 2-5 minutes.

Even worse would be a gas powered still with no electric pumps for cooling.

jacksonbrown

Your right Dad. An automated system designed by a peanut is a potentially dangerous thing. Having faith in something that won't work.
Luckily I don't do things half arsed.
I can shut a valve to kill the flow instantly and I won't loose any vapor.
My element won't run unless there is enough flow to condense the vapour and the condensers holds enough water to condense any vapour produces from residual heat.
Explain how a normal system is much better?? What would happen if you pop a hose upstream of the still. If your on mains, what happens if the council decide to do some work on your street and through the valve or someone runs off the road into a water-main/hydrant.
Nothings fool proof but show me a better alternative and I give it a go. Don't let paranoia, fear and ignorance cloud your better judgment, we've got HD for that.

grim

It's a perfectly reasonable/valid point.

Here is the strategy we use:

Monitoring Vapor LEL%

Monitoring Distillate Temperature

E-Stop Button

Emergency Shutdown disables everything but condenser recirc. pumps, and will move coolant valves to 100% flow. Everything else gets shut down. Steam boiler, condensate system, temperature monitoring, controls, networking equipment in the still controller, etc. Actuated steam valves go to 0% by default (close on no-power). So, we have some minor low voltage power to the valves and the mains power to the pumps, but that's it in the general still area.

Button will trigger it, exceeding the LEL% setpoint will trigger it, high distillate temperatures will trigger it.

From my perspective, keeping the recirc pumps running and at 100% in an emergency situation is a better option than shutting them down, for exactly the reason you mention. It's a tradeoff between two non-ideal situations.

Could always add a generator if we thought that it would be an issue - we considered doing this to be able to keep ventilation running in a power outage as well.

In a situation where a pump failed, the distillate temp would hit shutdown temps and trigger the emergency shutdown. Could always add the flow-monitors to the coolant lines too. You could blow off the steam main with a solenoid easily if you were using manual valves. Cutting the jacket pressure to atmospheric will very quickly cut power input to the boiler, there is carryover though.

dad

Oh no...no fear here...

I have the luxury of holding ponds outside, but I'll have a cooling water reservoir(s) above the still that feeds the product and reflux condensers by gravity. The reservoir will be replenished by pumps and a float valve. At no time does the water reservoir get below a standard that would suffice to feed the condensers until shutdown.

In addition, the reservoir(s) will be my deluge fire suppression, or at least part of it.

grim

Funny, very similar, our reservoir ended up higher than the still because it was convenient to put it on top of the boiler room, bottom reservoir is underground. It will gravity drain through the condensers with the pumps off, if we open the drains.

jacksonbrown

@grim said:

From my perspective, keeping the recirc pumps running and at 100% in an emergency situation is a better option than shutting them down, for exactly the reason you mention. It's a tradeoff between two non-ideal situations.

Like you say it depends on the situation. If my low flow switch triggered then cutting power to the pump was to protect it. Keeping it running with no flow won't help. It's either dead headed due to a blockage or it's running dry. Either way it's better to cut power to it and there are also check valves to prevent back flow.
If it wasn't a low flow situation that triggered the shutdown then it probably would be better to go to 100% flow.
Different trigger, different scenario, different action to be taken. That's how I'd approach it. All part of a good HAZOP.

dad

grim...yours is the other reservoir above the boiler I've seen...accident or not, good show.

Add a few pieces of PVC and its a fire extinguisher. Also works passively. Fire melts tank, tank drowns fire.

Harry

@dad
Your setup (and many other recirc systems) are just crying out for a ram pump. No electrons necessary. You can even build one out of poly pipe fittings (DIY) for cheap. Watch the video. Look up the others on youtube as well.
Here's a video of a pro unit used in New Zealand that shows the thing...

https://www.youtube.com/watch?v=b2kv8BUVy6E

dad

I may get to a Ram Pump some day. I have a son pushing it.

jacksonbrown

That's pretty cool Harry. Thanks for putting it up.
I guess someone was wondering how to use water hammer to advantage. You could probably do something similar with two impellers.
A high-flow/low-pressure drive impeller driving a low-flow/high-pressure one. On the same shaft it would only be one moving part. A bit like a turbo on a car.
Those kiwis have got two big advantages on most people though, lots of spare mountains and plenty of water they can afford to waste.

grim

Used air lift pumps with big aquariums for many years. Never thought to use that in this application though. Given they run only on air, it's about as explosion proof as you can get. The flow rate is non-linear though, and you do get entrained air right off the output.

grim

And Dad, if that tank ever bursts, fire or otherwise, god help us with the slip and slide out the front door.

Harry

@grim Air lift pumping is a different animal to a ram pump. Air lift pumps for water coolant lines is ok. But please don't use it for column feeds in either primary feed or 2nd column bottoms recycling. The idea with all columns is to purge as much air as possible before starting column distilling. Purge the column, purge the feed of dissolved air. Else there could be air AND ethanol in the column. All it needs then is an ignition source (eg elec sensors etc) and you've got BOOM. Of course you'd be well aware of this possibility but others seeing an air lift setup on a water cooled condenser might think "Ok, why not on a feed?", and would come to grief right quick. Just a word of caution.

grim

They both have their applications, but I really wouldn't bother with either.

By the way, we are very happy with the Grundfos Alpha recirc pumps. On low speed (in our system) they recirculate 4 gallons a minute at less than 6 watts, at high speed they circulate 14 gallons a minute at about 35 watts. At middle it's basically right in the midrange.

Was shocked at how little power these guys used. The fact that they have a GPM flow display on the face is a second nice touch.

If I would do anything differently, I'd try to find the stainless pump head models.