Posted by: etwombly on Apr 14, 2010
Tagged in: news
Last Friday I met with a small engineering/fabrication company to look over a list of possible improvements to the plant to bring it up to the standard where it can run in a production mode.
The primary modifications discussed are the possible solutions to the problem of getting char in the oil. We are discussing a new idea that we really had not thought of before along with the ideas I referenced in the previous post. We had been considering making modifications to the air flow through the internal cyclone and/or adding a second cyclone and filter.
A few days ago I was studying the way industrial cyclones function. They are pretty common in applications where there is a need to separate dust or particulates from air streams. The statement that helped us identify a possible problem is as follows:
"The bottom outlet is required to be air tight so no air bleeds into the low-pressure central vortex. If air does leak through the bottom outlet the particles on the outside wall of the cyclone are re-entrained in the air stream and are sucked up the inside vortex and out the gas outlet nozzle."
There are three cyclones on plant, all the other cyclones on the plant and dryer have the bottom air leak solved. The one on the dryer actually has an airlock on the bottom. The one just after the fan on the outside of the hotbox had the base of its tube in the biooil so no air can leak into these cyclones.
The one inside the hotbox at least on our plant just leads into the Char/Shot return auger. This auger is 1/2 to 3/4 full of shot but there is always an airspace above the shot so the char can fall in. This space is open to the trammel screen area on the top. It is also open to the gas producing area from the Main (flat) Char/Shot auger with its expanding gasses which I'm sure are not 100% blocked by the shot. When we put a bigger fan in even though we could adjust the speed it just made more vacuum pressure in that cyclone drawing all the char through the cyclone instead of knocking it out.
I have found a manufacturer that produces airlocks that can be installed in a high temperature environment. We are now considering if this might be the best method to solve the char getting into the oil issue. I'm presently talking with ABRI and the engineering firm to see if they feel this would be the best course of action.
We are also considering putting a number of new controls on the plant to make it easier to run at the same time we make the char removal modifications.