After countless hours of reading countless threads of info and ideas (I thank you all for it) I have put together an initial design to expand my coffee roasting capabilities. However, the power of your collective minds is great to say the least. I would like your help with my design, please critique it and share you knowledge with me and the forum.
I've started talking with a few machine shops to fab this prototype together, but I have to get a solid design down first.
I've attached my base design. I tried to do it in isometric to get it all in one drawing, obviously my iso cad skills are not as good as my 2d (I also tried modelling it in 3d where my cad skills are even worse). I hope you can zoom in enough to see the text. if any troubles viewing it, right click on it and save it to your computer where you can zoom in further.
I will list off major components:
LPG Burner- going to use a propane burner for lack of 240V, plus it will fare better in the winter and not hold any residual heat during the cooling phase. I've seen Sievert torches and I've also seen some Air-exchange gas burners. Any suggestions for which burner to use for maximum heat transfer and not susceptible to high winds blowing at it (forced air).
Fuji PXR with electronic valve control - want to use a PID with an electronic valve to control the propane flow (heat source) automatically. The Fuji PXR is capable of this. It also has programmable ramp/soak functions which is great. Does anyone know of a computer program that can operate the fuji in a more functional manner, or am I stuck with the manufacturers generic program?
Vacuum Motor blower - looking to keep it around 15 amps. I saw the Domel 7.2" motor, is that going to be enough to fluidise 5 lbs? How many pounds can it generally handle? (thinking of the possibility of expansion in the future) I'm Going to divert the air to create a negative atmosphere and aid in chaff collection. Thank you lmclaren for the idea of the venturi principal put into effect. it will also significantly reduce the exhaust temperature.
Chaff collector - I have no idea how to actually do this. people mention a conical trap thing. will that work in the setup after the 'venturi'?
Borosilicate Roast Chamber - Planning on using a 6" Roast chamber, since the borosilicate has a low heat retention, it won't effect the cooling phase greatly, and I can cool the beans right in the chamber. I also want to use borosilicate tube where the torch is, so I can see how cool the flame looks as it gets bigger and smaller based on the pid. (and to see if it is lit or not)
Dumping - Of all the posts I've read, no one really mentioned how they dump their beans from their tall machines, I can imaging trying to tip this thing over would be a pain in the butt/stupid. So I thought of a sequence of a swivel shaft. A dual position shaft that sits under the perf plate. While roasting, you put the open bore tube in place,then with the handle, you can switch it over to a tube with a chute that aims to the side. once that is in place, the perf plate will be housed in a custom made flange that swivels it out as well, so you pull the perf plate out and the beans flow down the chute into a bucket or bag or whatever. These will have to be custom milled for sure, if not custom cast. And probably the special flanges that hold the rod that creates a pivot point (Has anyone seen something like that in industry? can it be purchased?). I'd like to do a bubble bed going instead of a conical roast chamber, just because it is more fun. any advice on perf plate hole design?
Computer/ control panel - I'm going to get a nettop (small computer) to run all the programs. I'll get a couple small LCD touch screens, one for the PID program, and the other one running artisan or some other graphical program to see the roast in progress. (is there any program that can run the PID AND graph the roasts ?) The PID will also sit in the panel to be able to switch to manual mode, where I use the pid buttons to control the heat and a reostat to control the fan speed. The fan speed will always be manually controlled.
Ok, I think that is all of it. Give me your thoughts. let the madness begin. I want to get this thing built!
Burner - a sievert 2941 will do it. 7kw at 2 bar, 12.5 at 4 bar. Wrong there is lots of residue heat in the system.
I am roasting 6kg (13lb) batches with a 230v 1400 watt blower just changed it from a 1200watt.
I lift my RC off dump in 5 seconds flat, cool in 3 minutes. Cooling on board will be more like 7 minutes or more. Because I cool outside of the RC i can easily do 4 batches an hour.
How much you roast with any given blower (and efficiency) will relate to type of perf arrangement. Conical or asymmetrical type would be IMO be preferred over a fully perforated base in the RC or bubble bed. If you want to go that root you may want to look at recycling some of your exhaust to gain efficiency. This would rule out using a VC blower if you start recycling too much hot air.
Blowing the beans out is another good option to dump the beans.
Late here now more another day.
Rob
VBM Minimax 2gp, 1gp Reneka Techno, 2 gp la Pavoni Pub, la Cimbali M28, SJ Maz, FB 6kg HM roaster and other stuff
Can you post a larger image? BTW, use a 35° 16' iso ellipse to draw the U turn at the top. Hint: its minor diameter is always perpendicular to the circle's center.
I don't know the performance of th Domel. Have others used it in a similar size roaster? Have you compared it to my tests results in the Download section?
The conical chaff collector is called a cyclone separator. Very simple construction, no moving parts.
Rob, are you sure the 2941 is sufficient? Perhaps the 2942 at 26kW?
Hi James,
Nice concept. Pressurized evacuation would work easily. I'll try to attch this video....
Good Luck! -Scott (freshbeans) YouTube Video Edited by freshbeans on 07/24/2012 06:22
Fuji PXR with electronic valve control - want to use a PID with an electronic valve to control the propane flow (heat source) automatically. The Fuji PXR is capable of this. It also has programmable ramp/soak functions which is great. Does anyone know of a computer program that can operate the fuji in a more functional manner, or am I stuck with the manufacturers generic program?
I'm not sure if Artisan or any other PC based logger/controller can take over the ramp/soak functions of the Fuji. It would be neat if it could. If you go with the PXG series (not that much more expensive) you can take advantage of programming ramp segments in seconds versus minutes allowing very fine tuned profile curves. It's just a matter of keeping a list of ramp segment data for each profile and then you just punch them in for each desired profile. You can punch a set of time/temp's in less than a minute. You'll have to set a min/max output % on the Fuji to not over or under fire the burner.
Continuous perf (Sono Fresco, Freshroast style) will work fine for you without recirculating although the bubblebed will take more input BTU's if you run the convection throughput as high as Zoellner set up his Nepro Vortex Fluidat for "flash roasting". If you're not planning on a 4 minute flash roast which I would not recommend, then bubblebed will not be a problem without recirculating.
As previously pointed out, you'll have residual heat to deal with during cooling unless you build everything from the burner section up out of very thin guage sheet metal. With this you'll probably be fine but obviously not as fast as dumping into a cooling tray immediately after end of roast.
Keep us posted on progress with lots of photos.
Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
"Development of flavor, aroma, and body in the coffee bean is a chemical process which requires absorption of a definite number of heat units per pound of coffee-in the shortest possible time and the lowest possible temperature." - Sivetz
Dumping - Of all the posts I've read, no one really mentioned how they dump their beans from their tall machines, I can imaging trying to tip this thing over would be a pain in the butt/stupid. So I thought of a sequence of a swivel shaft. A dual position shaft that sits under the perf plate. While roasting, you put the open bore tube in place,then with the handle, you can switch it over to a tube with a chute that aims to the side. once that is in place, the perf plate will be housed in a custom made flange that swivels it out as well, so you pull the perf plate out and the beans flow down the chute into a bucket or bag or whatever. These will have to be custom milled for sure, if not custom cast. And probably the special flanges that hold the rod that creates a pivot point (Has anyone seen something like that in industry? can it be purchased?). I'd like to do a bubble bed going instead of a conical roast chamber, just because it is more fun. any advice on perf plate hole design?
The only issue I can think of with the 'dual position shaft' would be keeping the joins air tight so you aren't losing any hot air at the joins.
I dump my beans by removing the roast chamber from the base. It was designed to allow easy removing and dumping. I don't have any exhaust ducting or chaff collector yet though.
Edited by John Despres on 08/02/2012 16:56
I am using a 2941 to roast batches of typically 6 kg. Tonite I tried a batch of 7.5kg, worked fine, total roast time was about 13 minutes. Ambient temperature was about 7deg C and humidity 80%. I did use a 1kw fan heater to preheat the air going into the blower for this roast. I would say that this is the limit for this burner. Using a 2942 inside a 6" pipe I found it snuffed out. This may be because it was not running at high enough pressure and the air flow in the 6" pipe was at too high velocity. The 2941 seems to be have a wider latitude in the range it can run at without snuffing out.
Rob
VBM Minimax 2gp, 1gp Reneka Techno, 2 gp la Pavoni Pub, la Cimbali M28, SJ Maz, FB 6kg HM roaster and other stuff
Rob, That's good to know. Not only the batch size it can roast, but how it compares to another burners. With enough comparisons we'll know enough about these larger burners to make better recommendations and choices.
Since I have been warned about residual heat, I am going to redesign this roaster to incorporate a cooling system.
Few questions, at a 6" diameter, how tall should I have the RC? That being said, is there any disadvantage to upgrading to a 8" diameter? any experience on how it will effect the airflow (meaning bigger fan)? Especially if I go with a bubble bed design...
I am leaning towards a larger diameter because I would like to keep this machine under 6' and a larger diameter means shorter height.
I am thinking of moving to design a dual chamber system (Roaster + cooler). it would look really cool. I can have a design by later tonight.
Since I have been warned about residual heat, I am going to redesign this roaster to incorporate a cooling system.
Few questions, at a 6" diameter, how tall should I have the RC? That being said, is there any disadvantage to upgrading to a 8" diameter? any experience on how it will effect the airflow (meaning bigger fan)? Especially if I go with a bubble bed design...
I am leaning towards a larger diameter because I would like to keep this machine under 6' and a larger diameter means shorter height.
I am thinking of moving to design a dual chamber system (Roaster + cooler). it would look really cool. I can have a design by later tonight.
It seems that his 6" dia RC maxed out at 2 lbs. My only experimentation was with room temp air with green coffee in a paint can which was around 7" dia. Best bean movement was with 2 lb green. Not sure how much more you'd be able to roast in an 8" RC.
FWIW, getting a smooth fluid bean return to the spouting areas from a bubblerbed RC outer perimeter is problematic with the round RC's I've seen so far. Not sure what the solution is.
Another route for you would be to go with a continuous perf bottom as in the Sono Fresco. An 8" RC should get you around 4+ lbs. With this design you're not faced with the perimeter return problem of the bubblebed and RC height can be shorter than a spouted bed since you don't have the taller single spout. I'm guessing you could get away wth around a 12" tall RC.
The Domel 7.2 should handle it fine with either of these designs.
Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
allenb, any pictures of a continuous perf bottom? I don't quite know what you mean by it, or what the difference is.
Attached is a revised design.
Its a dual chamber system. The RC stands higher than the Cooling Chamber. after a roast, I can swivel the chute over and dump the beans via gravity into the cooling chamber, switch over the air to the cooling chamber via a diverter valve and cool the beans while I fill the roast chamber with a second batch ( will eventually design in a hopper system). Once the beans are done cooling, with the same swivel shaft system I can dump the cool beans into a container.
The drawing is getting even hairier, but I think it best depicts the layout if you can make sense of it.
I like the ideas you've got here. I wish I could do CAD! I can't even go there...I'm too A.D.D. as it is!
Anyway,On the floor of your assembly, there seems to be a manifold of sorts to distribute airflow for various purposes.
My 2 centavos would be to use the airchamber below the furnace as the air manifold for all those functions.
Mount the blower directly to that chamber...then branch out from there.
It would likely make your design more compact, and reduce the air restriction created by long runs of narrow tube.
See image #4 for the Sono Fresco (Coffee Kinetics). Looks like I was off a bit on the % open area. The % open area shown for the alpenroast drum doesn't seem to be accurate, looks to be way more open than 50%.
Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
So I would like to stir the pot a little, so to speak.
What is the forums thoughts on the difference between a traditional conical shape roast chamber and a 'bubble bed' or other types of roast chambers in terms of actual fluidization of the beans?
So when I watch videos of the conical or asymmetrical design, it seems as there is one small plume of hot air and that causes a slow circulation of the beans through displacement. Whereas when I watch videos of a bubblebed, or even Dirty Dans Rotational airflow (see video), the beans are much more fluidised and it looks as though more of the beans are in a good state of suspension.
I would think that would provide a more efficient and profilable roast would it not? YouTube Video
Also, RoasterRob had mentioned that if I went with bubblebead route, that I would have to recirculate hot air, can you elaborate on that more? I can imagine the only need would be a high enough pressure to fluidise an adequate amount of beans.
What is the forums thoughts on the difference between a traditional conical shape roast chamber and a 'bubble bed' or other types of roast chambers in terms of actual fluidization of the beans?
So when I watch videos of the conical or asymmetrical design, it seems as there is one small plume of hot air and that causes a slow circulation of the beans through displacement. Whereas when I watch videos of a bubblebed, or even Dirty Dans Rotational airflow (see video), the beans are much more fluidised and it looks as though more of the beans are in a good state of suspension.
Jamie
Great question!
A misconception is that the spouting bed (conical) in whatever form is only heating the beans within the spout and not the rest of the returning beans. This is incorrect. The returning beans are also being heated by the air stream although at a much reduced rate depending how far away from the upward moving stream.
If you watch the bean movement in a flat bottom (continuous perf) RC you'll see that there is a randomly changing upward bean movement wave instead of a more stable spouting action with the conical RC. So even with this type of RC, you don't have all the beans perfectly fluid at one time and therefore you still have some beans "on heat" while others are "off heat" so to speak although more beans will be on heat than the conical RC. With this being said, I personally don't believe there will be a noticeable difference in the cup with all other factors in a roast being equal. After further review of the bubblebed's bean movement it looks like what you really have going on is multiple spouts with multiple return paths within one RC but with more fluidization around each of them.
It would be nice to cup coffee's from an A-B test in a real roasting/cupping lab from both types of roaster.
Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
Seems to me that a conical spout would not need as much air pressure to create its single spout as compared to a bubble beds air pressure to create its small multi spouts. Thus could the conical be a more efficient way to roast as compared to the bubble bed? (less pressure = less energy required to heat the air stream)
Where is the "professor smiley" when I need it?? :smily-538.gif:
Len
"If this is coffee, please bring me some tea but if this is tea, please bring me some coffee." ~Abraham Lincoln
I can attest to folks being out and about. Me and Julie were out hitting the garden centers for loading flower pots all day. Nice weather! Tomorrow the Kamado/egg gets fired up!
ginny
05/18/2013 17:32
Jack, it is quiet today, I think the lovely day has folks out and about.
ginny
05/18/2013 17:31
sbonder
thanks for joining us...
JackH
05/18/2013 15:28
Quiet here today.
zombie coffee
05/17/2013 11:02
ricksroasters
thank you for taking time to join us...
allenb
05/15/2013 15:56
nikijack Howdy and Welcome to HRO!
freshbeans
05/15/2013 13:57
FataMorganaCafe
ginny
05/15/2013 03:04
blong2001 thanks for joining us...
ginny
05/14/2013 13:54
that is sweet... thanks for posting lylabrown...
for you
thanks for joining.
for you