Jacketed boiler learning curve

[LWTCS]

Do you know how much space you have?

[Hounddog1]

Yea I guess that makes sense. My drawing is probably not totally accurate as far as where the sight glass is positioned. The space between the bottom of the jacket and the boiler is probably roughly 3” or so and the space between the walls is probably less than an inch.

[shadylane]

Temperatures of the vapor and the charge are so different and variable that I saved myself from being confused by removing the top thermometer. The relationship varied with power, ambient temperature, weather, air speed, open or shut doors etc..

I hear Ya.
The pot and vapor temp should be the same, but when it's being measured the vapor will appear to be as much as 1 degree lower. This is caused by thermometer placement, passive reflux dripping on the probe or not having the probe thermally insulated from the still head. Personalty I quit measuring vapor temp due to inaccuracy. If you can spritz water around the outside of the of the riser near the probe and the temp decreases there's an accuracy problem.

[zach]

So I have a Auber DSPR 220 which is a PID controller as I understand it but it has a mash and distill mode. Mash mode maintains the set temperature and distill mode works on a percentage of output. In distill mode it has a high temp cutoff that was set to 200f which was causing me a problem so I set it to 206. Maybe I am not using the correct terminology but that’s how I understand it. Been using the exact same setup on a keg boiler without any issues but the jacketed boiler is a different animal.

What temperature are you using to control with? Is it the jacket temperature or boiler charge?

A 10% abv charge will boil at 199 F initially, but at the end of the run you need 210 F with 1% abv in the boiler to continue a strip.

If you use jacket temperature for control you still need to consider the pressure rating of the jacket and at what pressure the safety valves lift. At 2 psi saturated steam has a temperature of 219 F at sea level and might be enough to get through the run. At 5 psi the steam temperature is 227 F. I would keep your jacket operating pressure well below where the safety lifts.

You need to keep the water level in the jacket low enough so no liquid water touches the inner boiler to maximize the heat transfer of the steam to the boiler contents.

I would purge the air out of the high point of the jacket as soon as you have steam pressure. This will improve the performance of the jacket. Each time you shut down the vacuum breaker should suck air back into the jacket.

[NZChris]

The only 'temperature controls' on my pot stills are to cut the power to the element when the run is finished, or for if there is a problem with product output temperature due to a cooling water failure.