I decided to start a thread just on this topic. Hopefully things wont be so confusing. I should have started this thread a while ago. Sorry for the delay.
I built a Flash Boiler using Kladue's design. I built mine using copper tubing instead of SS. That build can be seen here. http://www.homebrewtalk.com/f51/flash-boiler-153116/
The MK-I is Kladue's and my latest project. The idea behind it is that the brewery will have a single heat source and it will instantly heat both strike and sparge water when needed. Hot gases from the boiler can be vented outside and indoor brewing would be possible without being asphyxiated. It will use superheated steam for mash temp infusion and then will use steam for the kettle to boil. Since it instantly heats both strike and sparge water there is no need for a HLT. In the other thread is where I started trying to boil using the Flash Boiler as a heat source. The first idea was to use an old immersion chiller I had made out of 3/8" copper tubing. Things didn't go to well with the two different tests I did using that tubing. Looking back on that I don't see why it wouldn't work using the 3/8" tubing, I didn't have things setup right when using the 3/8". Oh well. So another copper coil setup was built and bingo, I got a boil. Now things are moving in another direction. Klade and I are designing a scaled down version of a calardria. Kladue is the brains and I am just the guy putting it together.
Here is a link where you can check out the idea of the calandria.
I have been holding on to a brand new keg for about 5 years now. I have been waiting for the right build. I think now is the time. I cut out the top and cleaned it up to get it ready for the new life it has ahead of it.
The new calandria is made of 3.5" OD 304-304L SS tubing. I actually had to weld two pieces together cause I didn't have just one piece long enough for the job. The reduction is a piece of 321 SS from work. The cone is a piece of 718 Inconel from work. The hat is from the top of the keg. In these pics all the pieces are just sitting in place. There is a tube inside that the cone piece is sitting on for the pics. That is a 12" ruler.
This is about how things will be in the Keggle. This is being built to run 10 gallon batches.