product condenser wierdness

[jward]

While running water only for a cleaning/testing run I wanted to see how much power the product condenser could handle. It was a half hearted attempt since I didn't have the parts to run the PC off of the tap and rigged a pump pushing tap water from a bucket. The still is a sanke keg 15.5g boiler with a 5500W 240v heating element to a 3" column all SS configured as a pot still. I was running it full power with no cooling just steam billowing out of the product output end of the still for cleaning and leak testing for 20-30 minutes. I started up the cooling water to the PC and started getting a mix of steam and water. The PC didn't catch up right away which didn't surprise me since the PC is an SS tube dimroth and I don't mean a CSST dimroth. I didn't wait long and started dropping the power and kept getting steam and water output. Finally I dropped power down to 25% and quickly output was all water and no steam. I started moving the power up 5% or 10% every couple minutes to see what power would overcome the PC. The power got up to 85% without any steam output before I stopped the run. The water coming out of the PC got up to 146F but no steam. It seems weird to me that the PC didn't get quickly over run given how long it took to shut the steam down. I suspect either the PC would have caught up in a couple minutes even at the high power if I had given it a better chance. Everything was steamin' hot when I turned on the cooling water. Alternatively, maybe the boil didn't get rolling like I assumed as I increased power and would have over run the PC once it got back up to full 85% power rolling boil. Maybe the PC can handle 85% but not 100%.

I guess I am looking for a more experienced opinion on what happened and really looking to better set my expectations on how to expect the still to operate as I learn by doing.

When I run vinegar and water I'll be more patient and methodical not to mention have the PC supply properly setup.

[Oatmeal]

Water vapor behaves much differently than alcohol vapor. You'll get a better sense of your still running your sacrificial run. (In my only slightly more/less/or samely experienced opinion).

[still_stirrin]

Not much info available regarding your PC (dimroth), like tube diameter, gage, and length, although you said it is stainless steel. Heat transfer is a function of these properties.

Also, there is much energy in steam. Likewise, it takes a lot of energy to change the fluid’s phase from liquid to vapor, or in your case, from liquid output to vapor output, once the vapor from the boiler has been condensed (knocked down). This means, you must pass a lot of heat back into the pc to “reboil” steam that may have been condensed. All the metal inside and out from the vapor path must be heated enough such that the steam won’t condense when it contacts the coolant tube or the dimroth jacket.

Finally, you’ve noticed that there is a “reactive lag” in the response between adjusting the coolant flow and the condensing power transferred within the pc. It requires a stabilizing period to once again reach a steady state, or at least a stable state.

Interesting test.
ss