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1 lb. gas fired fluid bed roaster
Omega
I've been busy lately building a one pound+ capacity asymmetrical fluid bed roaster. I will list some of the components used if there is any interest.

I was inspired to build this roaster after seeing allenb's roaster here > http://forum.homeroasters.org/forum/v...ad_id=3174
Mine is quite a bit different (obviously) due to a different style blower and the limited tool and material selection. The design is meant to be modular and easy to modify. I can change burner and roast chambers without too much effort. Since the blower will easily loft 2+ pounds of beans, I may modify the roaster to handle larger loads.

The blower is an Ametek Lamb 116472; 112 CFM, 10.7 amps at full tilt. I run it at 45% with a fresh one pound load of green beans and steadily turn it down throughout the roast to raise the bean temp. At full throttle, the blower will lift the empty roast chamber right off the burner chamber; it's strong!

Here are some details; the roast chamber, coupling and burner chamber are all made from 4" steel conduit sourced from a scrap yard. The ID is 3.88". The coupling was made by slitting the conduit and fastening it to the burner chamber with a hose clamp and incorporating a shim underneath the coupling.

The burner chamber is set up to allow adjustments and modifications. The burner is mounted on a plate that is held in place by stainless steel nuts on two pieces of 1/4-20 stainless steel all-thread. The diffuser plate was mounted the same way, but I'm glad that it was easy to remove! (see why, below...)

The bottom plate in the roast chamber is .125" mild steel with 35 .125" diameter holes. The "slide" is .0625" mild steel, held in place on the bottom by two sheet metal screws (installed from the bottom) and a piece of stainless steel safety wire on the top side running down to the bottom plate. See the pics for a better idea of this part. (I found out that it's really hard to get a hand cut ellipse to fit into a not-very-round cylindrical roast chamber!)

The "black box" was sourced at Goodwill as was the maple cutting board base; both were $8 total.

The burner was removed from a camp stove bought on ebay, here > http://www.ebay.com/itm/301142242284

The first roast was done with the flame diffuser in place and not much in the way of temperature information. The infrared thermometer that worked so well on my modded popcorn poppers gave inconsistent readings, ie, they varied wildly. Because of this, the first roast was a total flop, the beans baked and never seemed to reach first crack. (They were really poor quality beans, so no great loss!)

I figured that I wasn't getting enough heat to the beans, so I removed the diffuser plate (see pics, below). On the second roast, I had the benefit of a bean temp thermocouple that gave a good idea of the bean temp. This roast was way better, but still a bit slow (19 minutes).

Before the third roast, I raised the burner .75" and pre-heated the roast chamber to about 320*F. The temps came up much more quickly, reaching first crack just before 10 minutes into the roast. Second crack occurred at 16 minutes and I pulled the beans shortly thereafter. Before the roast, I set the propane at 22psi and varied the bean temps by adjusting the blower output, using less blower as the beans lighten up.

I would like to have more "firepower" to allow for faster rate of temperature rise, but will experiment with raising the burner a bit more to see if that will suffice.

I'm really happy with the larger capacity of this roaster compared to the 4 or 5 ounces I could roast in a popcorn popper. I've got a large collection of very good popcorn poppers and they probably won't be used very often, now. I'm sure that at least some of them will find good homes with friends that want to roast their own beans.

Now for some pics! (Sorry I still have markings and layout lines drawn on various parts of the roaster, I'll remove them as I finalize the project and take care of the final details.)

i44.photobucket.com/albums/f44/barryk52/Gas%20fired%20roaster%201/Gasfiredroaster017_zpse85c6b98.jpg


i44.photobucket.com/albums/f44/barryk52/Gas%20fired%20roaster%201/Gasfiredroaster003_zpsafcbc6c1.jpg


i44.photobucket.com/albums/f44/barryk52/Gas%20fired%20roaster%201/Gasfiredroaster004_zpsc9568380.jpg


i44.photobucket.com/albums/f44/barryk52/Gas%20fired%20roaster%201/Gasfiredroaster015_zps18594442.jpg


i44.photobucket.com/albums/f44/barryk52/Gas%20fired%20roaster%201/Gasfiredroaster007_zps34e0259b.jpg

The bottom plate is held in with only high temp silicone. I didn't want to weld it in until I was certain that it performed well. The silicone has held up great through the high temps.

i44.photobucket.com/albums/f44/barryk52/Gas%20fired%20roaster%201/Gasfiredroaster014_zpsde5fd468.jpg


i44.photobucket.com/albums/f44/barryk52/Gas%20fired%20roaster%201/Gasfiredroaster005_zpsb7d8c2cd.jpg


i44.photobucket.com/albums/f44/barryk52/Gas%20fired%20roaster%201/Gasfiredroaster010_zps00fccb66.jpg


i44.photobucket.com/albums/f44/barryk52/Gas%20fired%20roaster%201/Gasfiredroaster019_zpse73c6116.jpg

Above is the heat diffuser that I removed to help get the temps a little higher during the roast.


i44.photobucket.com/albums/f44/barryk52/Gas%20fired%20roaster%201/Gasfiredroaster002_zpscfd18b49.jpg

The beans look better in person; the sun on some of the beans make them look lighter than they are. I'm very pleased to have a good roast after only one "teething" roast.


Barry
 
Omega
Here's a link to these pics at Photobucket where they can be viewed in a larger size:
http://s44.photobucket.com/user/barry...oaster%201

Click on individual pictures to view the larger size.

Barry
 
JETROASTER
Fantastic first build! First crack in 10 minutes is a great place to be this early on. Congratulations, and Thanks for posting. Cheers, Scott
 
allenb
Hey Barry, Plus 1 on all the positive comments on your build! This is a super build and should be getting you amazing roasts when you get to know it intimately.

I like the way the RC just slides onto the burner assembly tube as RoasterRobs designs do.

Are you able to cool your roasts in the roast chamber?

You should have more than enough fire power to roast as quick as you want without raising the burner. If you want to get more BTU's without going too high in propane pressure just drill out your burner orifice one or two sizes using orifice drills. Is that a needle valve or just a general purpose valve entering the bottom compartment? If it isn't, I would get my hands on a decent needle valve so you can drive your profiles via gas input pressure throughout the roast.

Great build!

Keep us posted on how the cupping turns out. BBQ grill

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
Omega

Quote

allenb wrote:

Hey Barry, Plus 1 on all the positive comments on your build! This is a super build and should be getting you amazing roasts when you get to know it intimately.

I like the way the RC just slides onto the burner assembly tube as RoasterRobs designs do.

Are you able to cool your roasts in the roast chamber?

You should have more than enough fire power to roast as quick as you want without raising the burner. If you want to get more BTU's without going too high in propane pressure just drill out your burner orifice one or two sizes using orifice drills. Is that a needle valve or just a general purpose valve entering the bottom compartment? If it isn't, I would get my hands on a decent needle valve so you can drive your profiles via gas input pressure throughout the roast.

Great build!

Keep us posted on how the cupping turns out. BBQ grill

Allen


Hey Allen, thanks for the compliments!

I can cool the beans in the roast chamber, but I prefer to dump them into a separate bean cooler that does a really good job. I like to be able to cool the roast as fast as possible. It's the way that I've always done it, but maybe I could try cooling in the RC, it would certainly simplify things.

The valve in the pic is a 1/8" needle valve, but it runs wide open all the time due to the need for all the heat I can get. I'll check into acquiring some orifice drills to get more ooomph out of the burner; if you have any sources or suggestions, I would appreciate you pointing me in the right direction.

About cupping, since I'm in the process of learning the roaster, I've been using some lackluster beans. The cupping will be mediocre, at best, until I use higher quality beans, which I have a good inventory of. At least I can use the not-so-great beans for a good purpose and maybe impress a few Folgers drinkers in the process!! Grin
 
Omega
Update: The roaster's need for more "firepower" has been solved. See details here> http://forum.homeroasters.org/forum/v...post_52412

I drilled out the burner jet with a slightly larger bit (a few thousandths larger) and now the roaster has plenty of heat to allow increasing rate of rise at any point during the roast cycle.

I've had two more excellent roasts from this home built unit and it's proving to be a terrific roaster!

Barry
 
Omega
Update:

I felt the need to eliminate the galvanized finish on the roast chamber. A very faint metallic taste was noticed in a few roasts and that was the main motivation. From what I have read, galvanizing shouldn't be a problem in a roaster due to heat. The heat that the zinc is exposed to is below the temperature where it vaporizes, a big problem with welding of galvanized steel. The issue might be due to the very slight abrasive action of the moving beans removing the zinc, which could end up on the beans.

There are several ways to remove the galvanizing (zinc) from the roast chamber, but the only workable solution for a long cylinder was chemical removal. I did this with a bath of muriatic acid. I had to strip down the roast chamber; remove the handle, remove the bottom plate (with perforations) and the attached slide plate. This wasn't too hard, but scraping out the silicone was a bit time consuming.

Warning: Muriatic acid is very hazardous to use. Proper safety precautions and protective gear must be used.

I used a 50% solution of muriatic acid and water initially, but it seemed to be taking too long. I added more acid and bubbles started to appear, meaning the acid was doing it's job eating away the zinc. I had formed a plastic trough that allowed about 1/4 of the cylinder to be submerged, so it had to be rotated about once a minute to submerge another section. I pulled the roast chamber out of the acid a few times to check the progress and to scrub the areas where the zinc still appeared. I finally got it all removed after about 40 minutes.

I arranged for a neighbor to weld the perf plate into the roast chamber once I got everything cleaned up and dried. Since he isn't a professional welder, I set up a dummy chamber and perf plate for him to practice on, so he could get the heat setting right. We got three good tack welds and that's all that it needed since there is very little mechanical force exerted on the perf plate.

So the roast chamber is back together and I will be roasting on Sunday. I'll post a pic or two showing the de-zinced RC in a day or so.

If you decide to build a roaster with a steel chamber or drum, be smart and don't use galvanized material.

Barry
 
Omega
Hey Pete! First off, welcome to the Homeroasters! I'm certain that we, as a group, can come up with a solution to the problem that you have encountered.

Here are some dimensions that might help:
Bottom of burner chamber to burner: 6"
Burner to the bottom of the RC plate: 2"
Burner diameter: 2-1/4"
Plate diameter below the burner: 3-1/4"
Gap from edge of plate below burner to burner chamber wall: 3/8"
None of these dimensions is "sacred", I just happened to be lucky that, with just a bit of tuning, the roaster actually works great!

I had an issue with the burner, initially. It had a weak flame and smelled like unburned propane, when the blower was running. I thought that it might be a differential pressure between the burner and the area below the plate, immediately below the burner, which at the time, was a solid disc. I drilled 1/4" holes in the plate (see pic) to alleviate the (supposed) differential pressure. For whatever reason, it worked and the flame was steady and doesn't blow out, even at ridiculous air flow levels.

There may be other things at play here that haven't been covered yet, like propane pressure, consideration of proper mixing of propane and air in the venturi tube and possibility of excessive turbulence in the burner chamber.
Perhaps allenb, or other well versed forum members, will visit this thread and offer some words of wisdom that could help out.
Check out the pictures below, they may be of some help.

By all means, keep us updated!

Barry

i44.photobucket.com/albums/f44/barryk52/Gas%20fired%20roaster%201/Roasterburnchamber001_zps39e38311.jpg

i44.photobucket.com/albums/f44/barryk52/Gas%20fired%20roaster%201/Roasterburnchamber004_zps1076a66b.jpg

i44.photobucket.com/albums/f44/barryk52/Gas%20fired%20roaster%201/Roasterburnchamber003_zps37c42254.jpg
 
allenb
I can't think of anything in addition to what Barry has covered on shielding the burner. These are good pointers.

One thing I'd like to ask before you try too many more things is where is your burner venturi air inlet located? Does it reside within the roaster?

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
coffeeroastersclub
Is that aluminum I see with the larger holes all over it? Is it exposed to any high heat? If so you may wish to reconsider its use. Aluminum has a habit of degrading/warping fairly fast in high heat.

Len

Quote

Omega wrote:

Hey Pete! First off, welcome to the Homeroasters! I'm certain that we, as a group, can come up with a solution to the problem that you have encountered.

Here are some dimensions that might help:
Bottom of burner chamber to burner: 6"
Burner to the bottom of the RC plate: 2"
Burner diameter: 2-1/4"
Plate diameter below the burner: 3-1/4"
Gap from edge of plate below burner to burner chamber wall: 3/8"
None of these dimensions is "sacred", I just happened to be lucky that, with just a bit of tuning, the roaster actually works great!

I had an issue with the burner, initially. It had a weak flame and smelled like unburned propane, when the blower was running. I thought that it might be a differential pressure between the burner and the area below the plate, immediately below the burner, which at the time, was a solid disc. I drilled 1/4" holes in the plate (see pic) to alleviate the (supposed) differential pressure. For whatever reason, it worked and the flame was steady and doesn't blow out, even at ridiculous air flow levels.

There may be other things at play here that haven't been covered yet, like propane pressure, consideration of proper mixing of propane and air in the venturi tube and possibility of excessive turbulence in the burner chamber.
Perhaps allenb, or other well versed forum members, will visit this thread and offer some words of wisdom that could help out.
Check out the pictures below, they may be of some help.

By all means, keep us updated!

Barry

i44.photobucket.com/albums/f44/barryk52/Gas%20fired%20roaster%201/Roasterburnchamber001_zps39e38311.jpg

i44.photobucket.com/albums/f44/barryk52/Gas%20fired%20roaster%201/Roasterburnchamber004_zps1076a66b.jpg

i44.photobucket.com/albums/f44/barryk52/Gas%20fired%20roaster%201/Roasterburnchamber003_zps37c42254.jpg

"If this is coffee, please bring me some tea but if this is tea, please bring me some coffee." ~Abraham Lincoln
 
http://www.coffeeroastersclub.com
Omega
Hello Len, the plate below the burner is mild steel; no aluminum is used in this roaster. Thanks for looking out for me!

Barry
 
allenb
Pete, Let's put a new thread together here in "Fluidbed Roaster" so we can track your fluidbed burner issues separately from Barry's build.

When you hit the "choose file" button and browse/select a photo file, make sure you don't preview it or it will not get uploaded into your post. If you find it's not the phioto you want when you post the reply you can edit it and load a different one.

On your burner issue. The venturi air inlet does need to stay within the body of the roaster so it shares the same pressure from your blower as the burner head itself. On my gas fired fluidbed build I ended up needing to block more than half of the air inlet holes to get a steady flame. Without doing this, the flame would lift off the burner slightly and I couldn't get complete combustion. You might need to try this with your burner. If you block off too much, the flame will exhibit yellow tips and then you'll just need to remove some of the blocking tape. I used foil tape used in sealing ductwork seams. I'll bet you can get your burner to work with a little more tweaking.

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
JackH
Hi Pete.

I agree with Allen, it will be easier to track and follow your build.

As far as posting photos:

Your photo must be 500 X 500 pixels and less than 244K.
Spaces in the photo's filename should be avoided.

Also make sure you do not use "quick reply" to post photos. Use "Post Reply" instead.

The Faq on posting is here:
http://forum.homeroasters.org/faq.php...?cat_id=16

There should also be information with resizing if you need it.

--Jack
---Jack

KKTO Roaster.
 
Omega
I wanted to update this build thread with a couple of pics and more info.

I built this roaster with the goal of roasting 1 pound at a time. The roaster has proven that it can certainly do that, but what is surprising is that it has easily done roasts of over 1.5 pounds, 26 ounces to be exact. (for the metric thinkers, that's 738 grams). It can roast more, but I haven't tried for a greater load yet. That will come with time.

Anyway, on to the pics. The newly added window is a nice touch and allows for a good view of the bean's change of state as the roast progresses.

The pic showing the entire roaster gives a peak at the roast air intake filter. In keeping with the roaster's low cost design and bare functionality, the filter housing is a bleu cheese container hot glued to the blower. The filter element is three layers of cheese cloth held in place with a heavy duty rubber band. It was a nearly no-cost filter, but is incredibly effective at keeping chaff from going through the blower and past the burner... (where it would catch on FIRE, then be blown out the top of the roast chamber!! NOT COOL!!)

The roaster has been a delight to use and is producing the most wonderful coffee, roast after roast. It's roasted somewhere around 75 pounds now and I'm extremely happy with it.

Barry

i44.photobucket.com/albums/f44/barryk52/Roaster%202_11_15%20001_zpsvf7wskl0.jpg

i44.photobucket.com/albums/f44/barryk52/Roaster%202_11_15%20007_zpsgx30n8du.jpg

i44.photobucket.com/albums/f44/barryk52/Roaster%202_11_15%20003_zpsutslzl2n.jpg
 
renatoa
What is the roasting chamber volume ?
I am interested about 500 grams of greens.
 
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