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All About the Bubble Bed Roaster
allenb
Top  #51 Print Post
Posted on 04/03/2023 6:14 PM
greencardigan wrote:

Quote

Looking forward to your new testing!

It's hard to believe that over 12 years have passed since you last posted about this. I miss many of the of the enthusiastic air roaster builders that contributed to the early discussions.


Yes there was a lot of major designing and building going on back then! Jkoll42 especially put in lots of major design and build time on his bubblebed build. He and I on each of our projects were both pulling our hair out back then trying to tame the beast to get it to produce a nice elegant flow and got close. After looking at various vids put together by Typhoon Roasters, I'm challenged to emulate the nice, calm, but fully fluid bean pattern they accomplished.
My motive for revisiting this was mainly due to wanting to build a 2 lb fluidbed for roasting coffee for relatives instead of using my drum at 1 lb batches. I was going to do a 2 lb Sonofresco (Syd and Jerrys, Coffee Kinetics) clone but thought, why not do a bubblebed perf plate instead of the regular symmetrical perf plate since I'm having to build everything else that would support it. So, I'll use the need for a 2 lbr to be the excuse for further experimentation with the bubblebed. It will actually only be a 1 1/2 lbr since I only have enough coiled nichrome and circuitry for 3 kw of heat which I hope is enough for this project.

I'll keep everyone updated.
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
allenb
Top  #52 Print Post
Posted on 04/03/2023 6:27 PM

Quote

Koffee Kosmo wrote:

I was looking at the video from above
It looks like 4 flowers pulsating cool


Hey KK, I rewatched the vid and you're right! Never looked at it in that light. I'm totally reworking the perf plate to allow 6 smaller spouts to cover a better area and hopefully offer more stability at different charge weights
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
greencardigan
Top  #53 Print Post
Posted on 04/03/2023 8:32 PM
I've had a random little thought bubbling in my mind for years. Maybe not a practical solution though.

I keep thinking of a fluidbed/bubblebed roaster with some sort of additional rotating plate or oscillating air deflector immediately below the perf plate. The plate or deflector could essentially create a continually moving higher pressure or higher flow area. In my mind, I imagine that it would move or oscillate using only the airflow, no additional motor or actuator.
 
btreichel
Top  #54 Print Post
Posted on 04/03/2023 10:36 PM
With a P1 and a hurricane lamp the potbellied sides seem to serve that function.
 
Koffee Kosmo
Top  #55 Print Post
Posted on 04/03/2023 10:47 PM

Quote

allenb wrote:

Quote

Koffee Kosmo wrote:

I was looking at the video from above
It looks like 4 flowers pulsating cool


Hey KK, I rewatched the vid and you're right! Never looked at it in that light. I'm totally reworking the perf plate to allow 6 smaller spouts to cover a better area and hopefully offer more stability at different charge weights


For infinite constant mixing
I was thinking of coloured light machine where a plate with different colours spins over a bulb

But for agitating coffee beans, my thought bubble is, have the spinning plate with 1 air outlet connected to the air blower via a flexible hose

If you want 2 outlets you need to have a Y connection to the blower

It’s just a thought bubble & I know it requires another motor for the plate rotation but it will alleviate dead spots in the agitation

KK
I home roast and I like it. Designer of the KKTO
Roaster Build information
https://homeroast...ad_id=1142

https://docs.goog...lide=id.i0
Blog - http://koffeekosm...gspot.com/

Bezzera Strega, Mazzer Robur Grinder, Pullman Tamper Convex,
(KKTO) Turbo Oven Home Roaster.
 
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allenb
Top  #56 Print Post
Posted on 04/04/2023 8:20 PM

Quote

greencardigan wrote:

I've had a random little thought bubbling in my mind for years. Maybe not a practical solution though.

I keep thinking of a fluidbed/bubblebed roaster with some sort of additional rotating plate or oscillating air deflector immediately below the perf plate. The plate or deflector could essentially create a continually moving higher pressure or higher flow area. In my mind, I imagine that it would move or oscillate using only the airflow, no additional motor or actuator.


I think I saw a patent years ago for a commercial grain drying machine that used something very similar to what you're describing although it took quite a few parts to accomplish the action. Another one was using a rotating plate with an opening that pulsed high pressure air into the chamber which caused the mass of grain to move at the frequency of the plate and sort of vibrate violently causing the grain to be suspended and moving about itself.
Hoping to create enough bubbling action with just the perf plate and possibly have rotation of the mass due to a spiraling vortex of the entering hot air below the plate. We'll see if it works out.

KK, your multicolored rotating Christmas tree light wheel sounds similar to the above. Too much complexity for me though.
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
allenb
Top  #57 Print Post
Posted on 04/06/2023 8:45 AM
As some may be aware, Typhoon Roasters developed a bubblebed several years ago and now offer several sizes from small shop roasters up to medium commercial size.

After studying their videos for a while I found that they departed from using individual spouts and instead utilize several spouting rows. To accomplish this, they drill a higher density double row with a low density single row placed in between each of the double rows. Not sure if they use the same ratios from Zoellners patent.

Here's a video where they show two different perforated plates so you can see their design.

Edited by allenb on 04/06/2023 8:56 AM
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
HarryDog
Top  #58 Print Post
Posted on 04/06/2023 5:38 PM
https://www.youtu...JI6CUidVjg

I have watched a few videos on the typhoon roasters but what do you think about the evenness of the roasts? At 4:30 you see a huge variance?

This is a 5kg roaster is it an issue when scaling up?
 
allenb
Top  #59 Print Post
Posted on 04/06/2023 7:18 PM
My guess is it's a coffee that normally has a lot of variation in bean color by nature. I wouldn't think the roasting method is contributing to it especially since the bubblebed typically can get away with lower ET throughout the roast.
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
allenb
Top  #60 Print Post
Posted on 04/07/2023 6:33 PM
I drilled another test perf plate yesterday and this time around I decided to try 6 smaller high density zones instead of 4 larger ones. Otherwise, I kept the same total number of holes for both the high and low density zones to stay with Zoelnners recommendation. The problem that both Jkoll42 and I had with beans hanging up on the side wall remains with this new attempt at a perf pattern.

Somehow, there needs to be enough air turbulence at the sidewalls to allow the beans to freefall back down and into the vortex swirls but not so much upward air flow as to cause the beans to travel upwards. I do not know how to accomplish this and maybe it's not possible without having air flowing into the chamber through the sidewall material.

The test was done using a hobby craft store clear plastic paint can with metal bottom that I drilled.

The bean charge is 2 lbs. Any less than this would allow channeling of the 6 spouts and a collapsed bed. This is the same issue Jkoll42 reported in his testing.

One thing is for certain about a bubblebed and to some extent with the sonofresco as well. The cfm needed to keep the coffee bed fluid is very high compared to a conventional fluidbed and because of this, the only practical way to heat the convection air will be to use a large percentage of recirc otherwise, the electric element or gas burner will need to be very much oversized which I'm sure Jkoll42 had to do with his gas burner. I noticed that the sonofresco 1 lb roaster incorporates near a 30kbtu burner although it pulses on and off for control.



1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
Koffee Kosmo
Top  #61 Print Post
Posted on 04/07/2023 11:00 PM
Thought bubbles ( pun intended 🤪)

1) Try 2 or 3 circumferences of outer holes a little larger than the inner holes
2) Leave a small 1/2” gap as a dividing line between outer and inner holes
3) Instead of circles segregate the inner section in triangles like cutting a pie in wedges and leave 1/2” gap between segments

I’m confident it will give you greater results

KK
I home roast and I like it. Designer of the KKTO
Roaster Build information
https://homeroast...ad_id=1142

https://docs.goog...lide=id.i0
Blog - http://koffeekosm...gspot.com/

Bezzera Strega, Mazzer Robur Grinder, Pullman Tamper Convex,
(KKTO) Turbo Oven Home Roaster.
 
Web
HarryDog
Top  #62 Print Post
Posted on 04/08/2023 9:15 AM
My single FB 1/2 pound bubble roaster has a dead area around the center holes, this is also bowl shaped to help the beans move back to the center to be pushed back up. The heater is out of a popper and air moves from outside to the center (To heat air) and is channeled using a pie slice support forcing the air to the middle and only place to go is up right under the spouting beans.

This works extremely well for one spout of beans but for multiple the trick might be to create a big enough dead spot for the beans to return, let them fall?
 
allenb
Top  #63 Print Post
Posted on 04/08/2023 9:53 AM
There's a bit of a dichotomy here. All areas of the chamber and especially the side walls must have upward airflow in order for the bean mass to stay somewhat fluid to allow it to float back toward the high density spouts and recycle. If the extreme perimeter is left as a dead area with no flow, the beans hug the wall and will not drop down at all. With incremental increases in perf area in this outer region, it starts to move but then starts shooting upward which is not what you want. There's no happy medium. Somehow, the sidewall becomes a sticky spot where it seems the air movement near the sidewalls force the beans to stick to the wall.

I noticed in the Nepro Vortex roaster they utilize a perforated sidewall and force air into them by using an additional fan.
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
allenb
Top  #64 Print Post
Posted on 04/08/2023 10:11 AM

Quote

Koffee Kosmo wrote:

Thought bubbles ( pun intended 🤪)

1) Try 2 or 3 circumferences of outer holes a little larger than the inner holes
2) Leave a small 1/2” gap as a dividing line between outer and inner holes
3) Instead of circles segregate the inner section in triangles like cutting a pie in wedges and leave 1/2” gap between segments

I’m confident it will give you greater results

KK


Although I've done something somewhat similar on the outer rim area, I might give your suggestions a try. It does sound like it has merit. With a bubblebed, you never know what will work and what won't work although I have a lot of experience in what won't work! Shock
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
Bhante
Top  #65 Print Post
Posted on 07/06/2023 7:42 AM

Quote

allenb wrote:

I drilled another test perf plate yesterday and this time around I decided to try 6 smaller high density zones instead of 4 larger ones.


Just a thought ... what about a sort of quasi sinusoidal ascillation in hole density as you go around the outer rim? Just add extra holes periodically around the rim, so that as you go around the density changes low ... high ... low ... high ...low ... high.

Take three consecutive holes around the outer ring and just drill an extra hole between them (i.e. 2 extra holes). Then leave the next three holes alone, and repeat the high density for the next three holes, and repeat all the way around the outermost ring. That should around 6 high density ring segments with low density in between, which I reckon should increase peripheral movement. And peferably decrease overall airflow somewhat, if possible.
 
Bhante
Top  #66 Print Post
Posted on 07/06/2023 8:59 AM
For the test rig, what about using thin perspex/fibreboard or some kind of thin plastic card/sheet, whatever is easily and cheaply available? It could be drilled much more easily and quickly than metal sheet, which translates to more and better trials and better end result. Perspex drills particularly easily. You want to avoid the more elastic types of plastic which would be more troublesome to drill. 3mm perspex is readily available, not sure about 2mm which would be super-quick to drill.

Did you ever try the roasted beans in the rig? If you are worried about them gettng blasted out, just make a lot of holes with a paper punch in the bottom of a dustbin liner, folded to make lots of holes quickly, and fix the mouth of the bag around the top of the test rig with rubber bands and packing tape. The bag should safely waft above the rig with the blower on, and if the coffee gets blasted out it all remains inside the bag. (In any case, surely for a test rig you need speed control on the blower? Just reduce the blower speed.)
 
allenb
Top  #67 Print Post
Posted on 07/07/2023 9:11 AM
The varying hole density around the outer rim may have some benefit and I may give that a try. If I do any further testing, I will give the fiberboard a try and I will not be drilling metal any more unless there is ample evidence the thing will fluidize properly.
No, I haven't roasted anything in any of my bubblebed prototypes since I was never satisfied with the agitation.

My original theory was that due to the low velocity air flow due to the bottom perforations being spread out all across the bottom of the RC, that any surface friction other than bean to bean would cause the outer beans to lack movement but looking at videos of the Typhoon roaster, they somehow overcame the problem since the beans are clearly seen moving up and down across the glass front with ease.
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
allenb
Top  #68 Print Post
Posted on 07/07/2023 9:23 AM
I think there's a reason why Typhoon does not build a round RC bubblebed. I think their idea of rows of holes in a repeating fashion sets up longitudinal waves that carries the effect on to the perimeter due to the wave effect carrying on to the extreme sides of the roast chamber. There's no way for this phenomenon to occur in a round chamber.
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
Bhante
Top  #69 Print Post
Posted on 07/08/2023 4:27 AM

Quote

allenb wrote:
No, I haven't roasted anything in any of my bubblebed prototypes


Acually I was referring to the earlier suggestion to put (cold) roasted beans in the test rig to see the difference in response. I still don't understand your response to that earlier suggestion, as you must surely have speed control on your test rig.
 
allenb
Top  #70 Print Post
Posted on 07/08/2023 6:52 AM
Let me know the post # so I can go back and take a look
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
Bhante
Top  #71 Print Post
Posted on 07/08/2023 7:42 AM

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allenb wrote:I think their idea of rows of holes in a repeating fashion sets up longitudinal waves that carries the effect on to the perimeter due to the wave effect carrying on to the extreme sides of the roast chamber.


I am slightly intrigued why you suggest there many be longitudinal waves in the Typhoon roaster, and yet you assert this cannot happen in a round chamber! The latter assertion is in case of fact incorrect! (Well, at least in part).

Have you seen waves in the typhoon roaster, or are there assertions from someone else that they have seen waves? Actually, one reason I suggested reducing the air speed is because I think the excessive air speed will break up the waves.

The Zoellner patent you referenced in the earlier thread relates, as far as I know, to a specific large capacity roaster built in Germany (40 tonnes, 4 tonnes ... not sure, maybe the former but I can't remember). I seem to remember the coffee tooks 24 hours or numerous days to cool. That roaster had a torroidal roasting region, and a slow-moving wave traversed around that torroid in a continuous motion. I witnessed a presentation concerning that roaster sometime around 2010 by someone who had seen it in action, including one or more videos (not just the Nepro video which I think is misleading).

Anything more specific I say about that presentation must be with that caveat that the presentation was a long time ago and my memory may not serve me correctly in some details. On 11th November 2011 I downloaded a copy of the Zoellner patent, almost certainly in response to a forum discussion on some coffee forum at that time, which I seem to remember contributing to - at that time obviously I would have remembered the details more reliably, maybe someone could find it with more success than I had yesterday (Homeroasters ... Home Barister ... Kaffee-Netz.net ...?)

I think there are two important hints in the Typhoon video we need to take stock of:

1) The hole pattern on those two plates seem to be identical, as far as I can see (see 1:45 - just one plate it thick and the other thin, and obviously for one the blower is turned up.

2) We are looking at more conduction, i.e. the beans are really in close contact.

According to my feint memory of the presentation, I saw a video of the wave movement in the actual roaster, and/or a small scale model (which was also torroidal).
 
Bhante
Top  #72 Print Post
Posted on 07/08/2023 7:52 AM

Quote

allenb wrote:

Let me know the post # so I can go back and take a look


#27, as reply to #25
 
Bhante
Top  #73 Print Post
Posted on 07/08/2023 7:54 AM

Quote

allenb wrote:

I think there's a reason why Typhoon does not build a round RC bubblebed.


Actually if you look at their patent they have a round screen. I am assuming this may be one of the bigger models, and/or earlier model.
 
renatoa
Top  #74 Print Post
Posted on 07/08/2023 8:04 AM
Patent yes, but Typhoon we are using here as a model, is square.
Examined the wide open Typhoon of one of our roasters, at least for this machine internal layout there is no sense to aim a round plate will not bring any benefit... conversely... will make sealing harder.
 
Bhante
Top  #75 Print Post
Posted on 07/08/2023 8:20 AM
My point was relating exclusively to waves. Could be either square or round, although arguably in the latter case might have to be torroidal.
 
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