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Bubble bed roaster
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Posted on 01/22/2025 1:20 PM
After several years of a heat gun and flour sifter roaster setup I've decided to upgrade. I want to build a 2kg or so capacity fluid bed roaster, and I'm intrigued by bubble bed designs, like Typhoon roasters. I've seen a few threads discussing them around here, but nobody has actually built one that I can see. I'm trying to work out factors like what the bean bed depth should be, hole patterns on the distribution plate, and airflow and pressure requirements. Has anybody here actually built one of these?
 
allenb
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Posted on 01/22/2025 2:57 PM
Welcome to HRO! Good to have another one whos been bitten by the roaster build bug! To my knowledge, I don't know of anyone who has built a roaster using the bubbling bed concept as seen in the Typhoon roasters. As far as bean bed depth and hole pattern, some of the videos done by Typhoon show pretty well what you would need for the hole pattern but not sure if they mention the hole diameter. The bean bed depth would have to be trial and error unfortunately. I've done some experimentation and from that, I don't think anything less than 2 1/2" would do without the spout collapsing. For air flow, you will need a blower with moderate static pressure capability (I'm guessing in the neighborhood of 10" h20 or so) but higher cfm than needed for a typical fluidbed since you are lofting multiple spouts versus 1. In order to keep from having an inordinately huge heater capacity, you'll need to recirculate the air back into the blower as Typhoon does. I'm not certain but I'm pretty sure Typhoon recirculates most of their roasting air.
Edited by allenb on 01/22/2025 3:05 PM
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
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Posted on 01/22/2025 3:21 PM
I'm going to try and start without recirculating to avoid some headaches with a high temp blower. I'm planning on using a 5700W dryer heating element.
 
renatoa
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Posted on 01/23/2025 3:28 AM
Welcome!

I seen a typhon opened down to the heater elements level, which are made with a lot of fins, similar with the water radiators we find in the front of any car... so if you need any details, just ask.
Even after that experience I am still puzzled to understand what prevents the beans from grouping in piles around the holes, and stay there for the whole roasting, thus baking uneven... confused
 
allenb
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Posted on 01/23/2025 6:47 AM
This is an example of what you're referring to of the finned tubular heaters found in multiples in a Typhoon roaster:
https://www.amazo...B0983753K1

They work well in a recirculating design since they aren't required to raise ambient room temperature air up to roasting temperatures. They aren't capable of large deltas with their watt density limitations.
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
allenb
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Posted on 01/23/2025 5:33 PM
For a good look at Typhoons hole pattern on their plate:

https://www.youtu...amp;t=132s
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
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Posted on 01/23/2025 7:41 PM
Oh that is very interesting. I don’t think to use different thicknesses of steel in order to get more or less conduction. Those holes also look a lot bigger than I thought they would be. They almost look big enough to let beans through.
 
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