The propane tube on it's own will simply not even move 1 cup of beans. The other issue is that even with the 'roasting chamber' 2 1/2 feet above the torpedo tube outlet the beans scorch immediately from the intensity of the heat, even within normal roasting temps. I will be introducing ambient temp air, but I will just jack up the temp of the propane tube. It could get to 400 degrees on low, 30,000 btu, so it should be able to do close to 700 degrees at 50,000 btu if needed. The additional number of feet it will have to travel will also get the heat source further from the roasting chamber, i.e. less intense. The nice thing about the squirrel cage blowers is that you can install a slide damper on the air intake to control air output. I could also install an air damper within the tube of the roaster if needed.
If I absolutely murder the temp, I will just have to buy a larger propane tube. The way it is currently setup just will not work. I have fiddled with stator blades, different distances between the roasting chamber and the propane tube, tapering the flow tubes from 7" to 4" and different configurations of the roasting chamber. Nothing worked.
Also, after researching these blowers, I would love to dissect a Sono. It has to be the a monster popcorn popper. The price of a blower, like the one I got, but that can withstand high heat air input, up to 700 degress, is between $2,000 and $3,000 dollars. They are made 100% out of steel. To me that means no commercial roasting setup would use that because of cost. We think roaster are expensive now, imagine someone key-stoning the price of a roaster utilizing that blower. So, they must have the heating source downstream within the same tube the blower outflow is hooked up to. With propane, I am not sure how I would set that up. On the other hand, with an electrical heating coil, I would install it inside the air tube, right in front of the blower outflow just as it looks in a hot air popcorn popper.
While looking at hundreds of blowers, I also think I caught on to Sivitz. His blowers look like massive square ventilation blowers that blow at 2,000-4,000 CFM. Again, they are only able to tolerate up to 200 degress F, so the heating source must be downstream, otherwise the heat would wreck the blower. On the other hand, his sample roaster utilized an $85 dollar heat adjustable hot air blower with a metal funnel on it, what does that thing sell for? I think $300.
The main thing is agitating, moving, suspending the beans in the roasting chamber. Once I have enough air to do that I can always find a way to add supplement the heat production. Without the ability to agitate the beans, I just have a smoldering pile.
I wish I had more money to work with. . . With all the research I have done on this project and a pile of cash I could make a pretty mean roaster!
Thanks,
Michael
