I have my methanol condenser all done, but would like to know how much water I would need to circulate through said condenser.

I was thinking something like a water fountain pump but I don't want to have too high a flow rate as heat transfer would therefore be reduced.

I don't have the dimensions handy, but the inner tube outer diameter is 3/4" and outside that is the 1" outer shell.

Spencnaz,

The easy way is to put a needle valve on the output and adjust the flow so the bottom of the condenser (the unjacketed part) is cool to the touch.

There is a bunch of math for telling you how much flow, check out a ChE handbook. But you have to find the K(?) value first which involves measuring the temperature of your condenser under steady state load in four places and measuring the flow rates.

Hey Rick,

I like the idea of the needle valve. I don't have the math handy to determine flow rates and Reynold's Number handy.

It's much easier to just ask someone who knows right?

I have a no contact laser thermometer, I'll probably use that to adjust the needle valve to get the condenser shell temperature down as low as possible.

I was thinking about a 110V aquarium pump to the top of the condenser and let the cooling water just drain out via gravity through the needle valve.

It works the other way. The cold water goes in at the bottom and flows out the top. That is if the top of the condenser is connected to the pot and the bottom to the distillate tank.

the higher flow rate in the condenser would mean you'll need to put more heat into the system..so higher flow rates are good.

do something to control the temps at the input to the condenser..this is where purity it controlled.

-dkenny

Would an inline thermostat to control condenser flow then be in order?

I use a small aquarium pump on 5/16" bore pipe on my condenser, this gives me more than enough flow.
As mentioned above, it's the head temperaturer that should be controled, the part where the codensing pipe comes out of the reactor, I control this to as close to 64c/147f as possible. It reduces the energy required to distil the methanol and improves purity, I consistantly get 96 - 97% when using a 5% prewash and 98 - 99% without, the vapor flow is controled by the venturi valve.
When you have 3 - 4% of the oil batch sizes in reclaimed methanol it's time to stop, you won't get much more economically.

I have had one batch of reclaimed meth which when compared with virgin on a set of good scales there was no difference in weight, and that's good enough for me, it was so good I used it for 3/27 testing.

spenc, your overengineering. If your cooling water is from a drum or tote, don't regulate the flow. If it's from the tap, then use a needle valve to slow down water usage.

The only temperature that needs to be regulated is the vapor temp at the top of the column. It's regulated by adding or not adding heat to the pot. Most people use a PID for that app.

Rick,

Sounds like you've got some sort of thermal siphon setup/concept there.

It's an efficiency thing. If the water flows counter to the methanol, then more heat is transferred. Also if you flow from top to bottom, it will have large air gaps. Air gaps are nothing but insulation that prevents that section of the condenser from transferring heat.

A thermal siphon would be doing it without a pump. I wouldn't recommend doing it without a pump if your drawing water from a drum or tote. The greenest way is to draw from a drum or tote and run the overflow from the condenser back into the same drum or tote.

You don't need a pump if your going to use tap water to supply it.

I understand the counterflow concept. My biggest concern is the pump.

The bus won't be connected to 'shore power' all the time. I was thinking about running a 12v pump just for the condenser off a 12v battery.

That will work. It does not take much flow to do the job.

not on the condenser flow but in the temp in vapors entering the condenser. this should control the heat being added to the pot.

-dkenny

dkenny, you are correct in what you say. If you're using a PID sensor at the still head this should control the heater. As evaporation has a cooling effect heat must be added to maintain still head temperature.

With my set up I've had methanol condesing at 117f/47c. Once I've got my 3% I'm finished. The Bio temperature never goes above 176/80c and the heater is of 80-85% of the time.