Re: Firebox condenser tube spacing
Thanks so much for the excellent info sources. Based on the table in your second link I hit the nail on the head (.312 pitch with .250 tubes) with my initial sketch. I include a link below so you can see my initial ideas.
I'd be very interested to see your spreadsheet. I'll be off-line for the weekend but will be back on Monday.
The .250 tubes (water in shell/vapour in tubes) seem OK for a condensate condenser but from what I'm reading, and what you say, could suffer from "choking" as a reflux. I'll likely redesign in 3/8" tubing. The idea is to make it as a screw-on component unit that can be used in a variety of applications.
This may be a bit overkill but 60,000 BTU *is* approx 20kW (~17.5). Efficiency of transfer into the still will reduce that but the online condenser calculations tend to bear out it's pretty efficient based on theoretical vs actual heat-up times. I had radial copper support channels (essentially fins) on the bottom of a copper tank over the flame.
Trid got me wondering so I did a test on the water supply and I can get 5.55 l/min @ 11C. So I think a 15"- 18" length is reasonable.
BTW, to Whammo57, nice work!
--- In email@example.com, "landrover_ffr" <sid.rains@...> wrote:
> I'm no expert on shell and tube condensor design but I'll through in my 2 cents. (BTW Iid never heard of them being called firebox or shotgun condensors until I joined here)
> Designing shell and tube condensor can be a complex business but at small scale (<2-3kw) a lot of this can be factored out by over design without much risk. As things get bigger the design get more involved so be warned, there is a heap of information out there as these thing have been used since the dawn of time (well at leat since the industrial revolution :)
> My gut tells me that you won't get away with placing your tubes that close together as the condensate could (will?) hold up in the condenser (and basiclly block it). FYI, I've spaced mine 6mm betwen tube surfaces and fitted 37x1/4 inch tubes in a 4 inch shell nicely. Based on my rough calculations my design at 20kW would need to be about 2 to 3 foot long. I post data once I get it steamed up.
> It might pay do as much research as you can before you start cutting copper, so here are a couple of links that might help get you started...
> I've put together a small spreadsheet model that could help you get started. I'll tidy it up and post it over the weekend but you will still need to make some big assumptions. By big I mean it would be easy to build a unit that was either far too big (i.e. wasted copper, my guess is you'll need about 20m of 1/4 inch tube) or too small (and you'll have to throw a power of cooling water throught it).
> It would still be a good idea to talk to an expert and try to bribe him with some product ;)
> Good luck.