Wednesday, August 10, 2011

Leak Hunting

I am at the stage in my gasifier build that is almost frustrating. I am very close to being able to make woodgas, but I have a thousand little details to finish up first. Let me be clear, this is not "about to run the truck" time. I have a ways to go yet. But I should be able to produce flammable gas with what I have, before everything is hooked up. I have to be able to do this to start the truck. A blower sucks air across the bed of coals, and heats them up. Once they are hot enough to produce gas, the truck may be started.

So I have to get the thing sealed up, tie up my loose ends. Sealing the leaks is very important, and very tedious. Here's what I rigged up to pressurize the cooling rack, so I can feel the leaking air:

The back end of the shop vac, hooked to one of the downspouts. I sealed off the post tops with duct tape, see the little silver domes?

Here's a video:

There were a few leaks, small ones. I don't have any RTV sealant yet. But I have this:

Yup. Don't laugh, it works pretty good. It's sticky and black, and when dry it's fairly tough.

Here it is applied:

Hard to see, but it's on both welds, top and bottom. Blends right in!

I have some other good sealing stuff, for removable parts:

Fiberglass rope, for stove doors. I glued it up with silicone:

It wraps around the joint where the hopper meets the hearth. Like this:

I also have to make a downspout for the monorator hopper. If I am brilliant enough, I can make this serve three purposes: A water column (manometer), a sealed drip leg for the condensate, and a safety valve.

All it is really? A pipe straight down from here:

I need an open ended tube, submerged in a container of water. As long as the vacuum doesn't overcome the 29"  water column, I am fine.

So I came up with this:

 Very small CPVC pipe with slot cut for "sight glass" - then wrapped in clear packing tape.

The other end, which has to fit the 2" pipe seen above. Kinda clunky, I admit. Gluing PVC to CPVC? It may not be sturdy enough.

The downspout so far. We'll see how it does. Again, I'm trying to stay under 29" of water column. To get a sense of vacuum power, I made a little test, and took video of it.

I also have to finish up the cyclone once I get ahold of some Hi-temp RTV. But for now, here's an interesting demo of the very fast spinning air: