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Husamka
10-14-2018 07:41
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10-14-2018 07:33
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Homeroasters.org » BUILDING A ROASTER » Fluidbed Roaster
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Recycle but not recirculate?
Lawnmowerman
Ok here goes. Ive been working out an air roaster design and the build is picking up some momentum. It started with an idea for a tube inside a tube, a kind of transparent shroud. But I cant build anything like that. So the idea morphed into a tube inside a box, and since there is extra space, run a finned sir intake tube thru the box, making it a heat exchanger. Anyone see any reason this shouldnt greatly improve efficiency?
Edited by ginny on 03-16-2014 04:29
Bad coffee prevails when good coffee roasters stand by and do nothing.
 
Lawnmowerman
I have the bake a round mounted in a box. Once I have all the cutouts, Im confident this will be stable, and hopefully protect it. The heated air intake tube is there, but needs fins. Ive been buttoning up the heater section this last week.
Lawnmowerman attached the following image:
cam00379-1.jpg

Bad coffee prevails when good coffee roasters stand by and do nothing.
 
Airhan
So you're going to pull air in through the tube on the bottom, heat it up on the other-side, put into the glass roast chamber on top, and then as the whole box heats up you'll pre-heat your air in the intake tube? That seems like a fantastic Idea to me.
Aaron
"Grind it like it did you some great injustice!"D.L.Clark
"Not all who wander are lost."J.R.R. Tolkien
 
Lawnmowerman
Ive got a temporary support to test this on. Im waiting on the heat exchanger part. Time constraints. The heatet and blower section isattached. Right now I theoretically have a working roaster. Its just a straight through design at this point. Ready to test with one of the two elements. I have a half pound of decaf sumatra to sacrifice soon. Two elements were included in case they are needed but Im hoping to use only one. Im hoping that it can do 500 gram charges when complete on only one element. But if not. Im leaving recirculation on the table. It would be nice to use the exhaust heat but not draw in smoke. Thats the point of this exercise.
Lawnmowerman attached the following image:
cam00407-1-1.jpg

Bad coffee prevails when good coffee roasters stand by and do nothing.
 
Lawnmowerman
The layout posted is not using any heat revovery. Its to see if my thermocoupling is ok. I have a bypass motor to draw in hot air and blow into rc. Now if I stack another box on top and include an openinginto the heatexchanger then out the bottom, i should be able to test this. So im looking at a bunch of stacked boxes. Another box on bottom will be custom built to keep it pressurized. I sure could use a tc4 on this but will have to wait. There are several areas on this contraption that i will need to monitor. My wife said make it unique. Hopefully ive included enough a the tried an true that if all else fails, it will still roast
Bad coffee prevails when good coffee roasters stand by and do nothing.
 
Lawnmowerman
Airhan, the air intake is at the top in the plan. It is heated in the tube not installed in the last pic. Then drawn into a bypass motor also not pictured, the up through roast chamber, out the top into anothr small box not pictured then into the heater box to do its work then out the bottom. I willalso mention that in the spirit of recycling, almost all of the materials used are recycled. Completion will take a while, but I wanted to get pics up early and more fully explain this crazy idea.
Bad coffee prevails when good coffee roasters stand by and do nothing.
 
Lawnmowerman
We dont have a dont try this at home section so I will mention it here: I took the cord and switch with a dropping diode from a damaged heatgun to see if it worked on a vacuum motor on half volts. It worked. But it ran so roughly i would not consider using it. Upon turning down the router controller, it got even worse, So... dont try this at home.
Bad coffee prevails when good coffee roasters stand by and do nothing.
 
oldgearhead
In my Bake-A-Round tube, I use:
__ 500°F air for 500g of decaf beans
__ 550°F air for 440g of SHG beans (will fit in quart jar)
__ 600°F air for 500g of SHG beans

One heat gun element.
So if you can simulate the heated-air-flow through the RC, you my be able to test for temperature before using beans...
No oil on my beans...
 
Lawnmowerman
A question. What is the maximum allowable et for fluidbeds?
Bad coffee prevails when good coffee roasters stand by and do nothing.
 
Lawnmowerman
So the decaf beans were not s good indicator of anything. Not enough experience with them. I roasted a 3/4 lb batch of colombian with both heaters on full. 1st crack @ six and a half. 2nd crack @ 8 1/2 minutes. It roasts.
Lawnmowerman attached the following image:
cam00419-1.jpg

Bad coffee prevails when good coffee roasters stand by and do nothing.
 
Lawnmowerman
The above pic is of the defects i could find. Too much heat, right. Thats why im needing info on max e t. Thanks in advance. This is my 1st fluid bed.
Bad coffee prevails when good coffee roasters stand by and do nothing.
 
oldgearhead
I can go to 700°F, but I never do. For me the sweet spot is around 500°F for the process heated air. More info in reply #8...
No oil on my beans...
 
allenb
Lawnmowerman wrote:

So the decaf beans were not s good indicator of anything. Not enough experience with them. I roasted a 3/4 lb batch of colombian with both heaters on full. 1st crack @ six and a half. 2nd crack @ 8 1/2 minutes. It roasts.


Boy, I'll say it roasts! I'm with OGH, 500F - 550F is a good limit to try and not exceed but, there's a qualifier here, this only works if you're able to measure a well mixed air stream with no variations from one side of the stream to the other which for most of us isn't possible. Because of this I would suggest to not be concerned much with ET entering your RC and just concentrate on not exceeding acceptable rates of rise for any phases of the roast. By doing this you'll pretty much be guaranteed to not scorch your coffee.

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
David
Lawnmowerman wrote:
The above pic is of the defects i could find. Too much heat, right. Thats why im needing info on max e t. Thanks in advance. This is my 1st fluid bed.


Yep, the divots indicate that the temperature on the ouitside of the bean was going up much faster than the temperature on the inside.
So, reducing the air temp is indeed the right thing to do.

Opinions vary, but in my readings 550F seems to be the max temperature in drum roasters with proper convection. Your fluid bed roaster will certainly have the proper convection, so I'd be inclined to stick close to the 550F as the max.

On my RK Drum, the sweet spot is around 525.

David
 
Lawnmowerman
Allen,OGH,Dave; thank you for your input. Very helpful. More pics soon. Plus tedious descriptions. I will say this much; this is turningout to be very rewarding project and is rounding up into a tidy little package. Ive hashed out the air routing schemes, simplified some things, and pretty much have the rest of the build in a step by step manner and the modularity of the design really helps with this.ThumbsUp
Bad coffee prevails when good coffee roasters stand by and do nothing.
 
boris
Hi LMM,

Any updates on this project?

I'm in the planning stages of building my own fluid bed roaster, and your idea to use a heat exchanger removes my biggest headache - how do you get the smoke out when recirculating?

Do you plan on taking some efficiency measurements once you have yoru system running?

-B
 
Lawnmowerman
Boris: its encouraging to see someone else has shown an interest in this project. The preliminary tests i did were enough to convince me that once this is completed i will have something that works and wasnt wasted time. The build lag time has allowed me to make refinements and also make less complicated. This roaster will have the option of heat exchanger or recirculation or both at this point. From what i understand from ogh`s build, we would use less recirculation at the smokiest parts of the roast. Im including this just in casr the heat exchanger isnt as efficient as i hoped. More okie engineering ahead. The easy part was mounting a 14 inch long bake a round inside a 12 inch filebox.
Bad coffee prevails when good coffee roasters stand by and do nothing.
 
Lawnmowerman
And yes i will have features that will test and compare efficiency.
Bad coffee prevails when good coffee roasters stand by and do nothing.
 
oldgearhead
Lawnmowerman wrote:

So the decaf beans were not s good indicator of anything. Not enough experience with them. I roasted a 3/4 lb batch of colombian with both heaters on full. 1st crack @ six and a half. 2nd crack @ 8 1/2 minutes. It roasts.


1) With the Panama Boquete I'm roasting now, the enhanced flavors seem to come from the roasts where the first crack came at 10 minutes.

2) The smoke leaves through the 'water door' at the top.
oldgearhead attached the following image:
dsc_9153_8.jpg

No oil on my beans...
 
Lawnmowerman
oldgearhead wrote:

Lawnmowerman wrote:

So the decaf beans were not s good indicator of anything. Not enough experience with them. I roasted a 3/4 lb batch of colombian with both heaters on full. 1st crack @ six and a half. 2nd crack @ 8 1/2 minutes. It roasts.


1) With the Panama Boquete I'm roasting now, the enhanced flavors seem to come from the roasts where the first crack came at 10 minutes.

2) The smoke leaves through the 'water door' at the top.

Bad coffee prevails when good coffee roasters stand by and do nothing.
 
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