This is the processor I'm building.. Its a 55 gal drum with a cone bottom welded on. There is a 4500w 240v water heater element in the cone.

Piping is black iron, and brass ball valves, The black thing is a venturi for injecting the meth.

I plan on using a PID for temp control, where would be the best place to place the probe.
Are there any other problems, or anything else I may have missed?
Thanks

processor.JPG (26 Kb, 108 downloads)

Best place to put it is at the entrance to the tank on the pump output.

Jon,

Thats what I thought too until my pump stopped pumping once. In that location with no flow the sensor will not see the temp in the tank and will keep the heat on !! I found this out when returning from lunch and finding the pid at 120f and the gage on the tank at 320f, quite exciting. Even though my pid is set to shut down the heat at a max temp of 250f, if it can't see it it won't work.
Next revision is to move the sensor to the pot a bit above the heater.

Tony

True, but if you wire it so nothing will be on unless the pump is on then it shouldn't matter. If the pump die, the heaters go off.

There is the rub!! It is wired that way, the pump was running but the impeller spun on the shaft!!

Tony

I see...Its hard to account for all the possible scenarios that "could" happen. The safest bet is to install the thermocouple in the pot near the heaters.

Or install a high limit control. Use a T-stat controlling a main contactor or even the H.L. that is standard on hot water heater T-stats with the red button, just strap it to the tank and put it in series with the low voltage PID output loop... High temp, H.L. opens thus removing power to PID...
Jon