Wednesday, January 25, 2012

Evap System Nears Completion

Work on the evap "can" continues nicely, although with the hickups of a broken mill and a short lack of welding gas. I've also invested in a new Horizontal Bandsaw! It has already proven it's worth, and I'm very happy with what it allows me to do.

Since, the mill has been fixed and gas has been gotten. Now its time to proceede with the construction of the evap system. I cut off a 3" section of 4" diameter stainless tubing from the excess on the end of the combustor, then cut , pinched, welded, and ground the piece untill it fit snugly inside the 4" flametube. I then welded it to the evap "can" base.

Folowing this, I drilled a 1" hole in the center of the "twin" plate to the one that is the base of the evap can. I cut another 2" circle as the base of the evap tree, and proceeded to drill 3 holes which will hold the evap "tree" onto the "can".  I then drilled a large 1" hole in the mount for the "tree".

To make the tree, I used a hole-saw to profile the ends of three 3/4" tubes (the branches) to fit a 1" main "trunk", then cut each "branch" at 45* so they would make a nice "J" turn twoards the front of the combustor.

I'm using two different fuel injectors for two different fuels. The first and foremost is the main fuel injector. This is a cone-pattern spray nozzle that will evenly cover the sides of the evap tubes with a spray of diesel to be vaporized and burnt during normal operation.
The second injector is for the propane starting fuel. The evaporative fuel system can't be used unless the evap tubes are hot eanough to vaporize liquid fuel. To heat them up for starting, I'll use a small propane "pilot" injector. This is just a standard brass hex-plug you'd find in the plumbing isle, into the sides of which I've drilled some small holes. The radial hole pattern will be better for heating than injecting propane straight down the length of the combustor.

More to come soon!