Monday, May 10, 2010

Look Out: SCIENCE!

I can finally provide a HERMS update. The project is coming along well. Below is a picture of my completed Hot Liquor Tank (HLT, on the right) and Mash Tun (MT, on the left).


Just to recap, HERMS stands for heat exchange recirculating mash system. The idea is that your mash undergoes different processes at different temperatures. But in a Rubbermaid cooler you can't heat it directly (well you can, but burning plastic is dangerous AND toxic, never mind the fact that your mash will be ruined). Here you heat the HLT; The mash gets circulated through a system of pipes and when the temperature needs to change, you send it through hot water (in the HLT) to pick up that heat indirectly. Yes, you're right, you don't heat liquor in a HLT, but that's what it's called.

I fashioned my HLT out of a decommissioned keg. I cut half of the top off (let the sparks FLY), and screwed a board onto the edge (seen in white) to mount my solenoid valves on. Soldering copper is easy, but time consuming, because it has to be done one joint at a time. Anywhere you see on the picture a sliver of silver, is where flux (white goop) was applied to both pieces, inserted together, placed in a vice, heated, soldered, dipped in water (to cool), and dried. Also, don't solder barefoot. When that solder drips off your pipe and hits the ground, that splat created tends to shoot under the arch of your foot and make you dance around your garage; with the door open; like an idiot, while your neighbors point and laugh.

I'm having my system circulate continuously, so the temperature in the MT stays consistent top to bottom. Using a PID controller sensing the temperature in the MT, the controller will apply a voltage to the solenoid valves when heat is needed. I picked the bypass valve (which doesn't send the wort into the hot water) to be normally open, and the coil valve to be normally closed. That way I can apply the same voltage to the both and they will switch positions. Also if anything goes wrong, it will fail to bypass, and not to heating, so I wont end up cooking my mash or melting my cooler.


I realize there's no coil in there yet. I'm using up all the parts I've purchased first, and then coming up with a list of parts remaining. 

My mash tank is installed with a Blichmann Autosparge mechanism (yes, it's basically a toilet float). I can remove the stainless float for the circulation process, and the wort will just continuously flow. When I'm ready to sparge, I can disconnect the host coming from the bottom from my HLT and place it in my boil kettle. I'll install the float, and sparge away. The float ensures that there will always be a certain level of sparge water in the tank, and if things get stuck, the stainless float will stop any more liquid from coming in.


Finally I've only just begun to start on my control box. And I've mounted a computer power supply in it to power my 12V DC solenoid valves.

Whew. Sorry if that was too much geek for you. I can't help myself. I've got engineer (and beer) running through my veins.

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