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JackH
12/14/2019 4:07 AM
I read somewhere that higher elevations have faster roast time and require somewhat lower temperatures. air is thin and has less Oxygen

allenb
12/14/2019 12:44 AM
Yes, 1st off, you must use only Panama Esmeralda Geisha beans and be sure to only roast on Saturdays. Actually, this isn't completely true. Please post in all about roasters forum. Thx!

wjohndon4566
12/13/2019 10:36 AM
I’m at 9,000 feet elevation, is there any special adjustments that need to be made to roast using an SR 540 at this elevation?

snwcmpr
12/07/2019 9:29 AM
roar

snwcmpr
11/27/2019 11:44 AM
greenman

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5 Lb Roaster Perf Plate Design Help!
allenb
I agree with Renatoa that you're exceeding the limit with this roaster. There is a practical bean bed height limit for any fluidbed in relation to the number of square inches in cross section. When the limit is exceeded, you go from a relatively continuous stream to an erratic pulsation due to collapsing pockets of air. I imagine that there is less tendency for the denser green coffee with less column height to do this as much.

I've heard some claim that going up to 550 F caused no noticeable degradation in cup quality in fluidbed roasting but would not recommend going over that. It is true that the lowest possible environment temperature should be sought that will still get your coffee through the profile on time.
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
pisanoal
allenb wrote:

I agree with Renatoa that you're exceeding the limit with this roaster. There is a practical bean bed height limit for any fluidbed in relation to the number of square inches in cross section. When the limit is exceeded, you go from a relatively continuous stream to an erratic pulsation due to collapsing pockets of air. I imagine that there is less tendency for the denser green coffee with less column height to do this as much.

I've heard some claim that going up to 550 F caused no noticeable degradation in cup quality in fluidbed roasting but would not recommend going over that. It is true that the lowest possible environment temperature should be sought that will still get your coffee through the profile on time.


I was initially confused on why you thought it was overloaded. But i rewatched my video and now i understand... So this..."When the limit is exceeded, you go from a relatively continuous stream to an erratic pulsation due to collapsing pockets of air" is only happening in the video because I turned the air down. If i had kept it turned up it would be a continuous stream. I was trying to keep a temp profile and failing miserably.

I should be within the general design parameters for the weights I am roasting. In fact in RoasterRob's sticky, he uses a 6" RC for 2.3 kg, granted its cylindrical, but that also means it has less cross-sectional area.

I do want to talk more about the heat issue. Do I need to move more beans? I feel like I am moving a small number of beans compared to the total bean mass and that may be part of the total issue. If it helps, I'm thinking in the theoretical sense. So what is it about a 20 pound roaster that allows the heat to stay lower? I feel like i'm not getting my question across correctly, but maybe you all will understand what i am after.

Is it an air volume issue? air pressure? cross section of beans moving?

One thought i had, is my perf plate hole density is a lot tighter then most of what i see on here.
Edited by pisanoal on 11/11/2019 2:51 PM
 
renatoa
Regarding heat... somewhere in this informational mess surrounding us, Schulman explain his routine for finding a given oven roasting capacity: drop inside an initial estimate of beans, at 200 C charge temp, and keep them there at constant 250 C air temperature, and good agitation, until FC.
If FC is in the 10 minutes ballpark, you are good, else play with quantity accordingly.
 
pisanoal
Useful information. Thank you.

I still wonder if there is a way to increase the "apparent" capacity of the RC.

For example, if i had one line of holes at the bottom of the RC, I would be able to roast a certain small volume of coffee. But if i were to drill another line of holes, my capacity would be increased (more hot air to the beans). You can take this model to the optimal point at which you have reached your true maximum capacity which would look something like highest bean charge with the "best" agitation of beans while still maintaining your suggested heat curve.

I guess my question is where is my limitation coming from and why do you think that? Is it..
a) the actual footprint of my roaster, or
b) my perf. plate design

I've stuck to the rules of thumb for a as best I can tell. So that's why I'm so focused on b. I also realize there are a myriad of other possibilities (blower, air inlet design, air outlet design, internal resistance, bean type, air temp, etc)

Also, I feel like I sound like I am being argumentative. So I just want to say that is not my intent. I very much value the input you guys are giving me. A lot of it is me trying to understand where your coming from on your responses so I can figure out if I can do anything about it.

Anyways, Thanks again for your help, its truly appreciated.
Edited by pisanoal on 11/12/2019 3:52 AM
 
pisanoal
I've been studying the RoasterRob's design elements thread and I've come up with a couple of things to try.

He states he uses roughly 20-25% of x-section for perf. plate.
I was at 12.5% in the latest video. I'm even lower on my last roast

He also states too high perforation density per area can cause issues with bean movement which is exactly the issue I'm fighting and definitely describes what my hunch has been.

So my fix is I have some aluminum plate that I am going to drill a new perf plate design into, and temporarily install that into the roaster. The plan is to use the spacing Rob has laid out over 25% of the x-section. I'll leave it close to the 45 at first and then try it at less then 45, maybe even all the way flat and see what I end up with. Hopefully i have time to do all of that this evening.

I'll be sure to post results.
 
allenb
We're not finding you argumentative and I'd be asking the same questions until I got somewhere so no worries there!

When you were needing to hit over 600 F to maintain desired ROR, let us know what the profile looked like in time/temp. I'm assuming you were never exceeding 30 F/min?

Depending on how thin the spout is you're seeing, it might improve going to RR's recommended perf plate % of cross sectional area. It doesn't take much for a fluidbed to do weird things. I'm interested to hear how your perf plate test comes out.
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
pisanoal
Not much change in bean mass movement. What I dont get is it doesnt make much difference if i have 3 pounds or 5 pounds, or even 6. The spout looks about the same although at least its more centered. I wonder if its a volume issue? I didnt try to roast though, so maybe thats what i should be expecting for greens movement, and the roast characteristics will be different

On temperature, when I was having to hit over 600, I was finishing the roast in about 15 minutes. ROR was ok in the beginning, around 50 at first, then droppong steadily after the beans hit about 225. It levels off at about 15 for the rest of the roast, but thats me pushing the ET higher and higher to maintain that.
 
CoffeeInterest
Perf plate does matter, but less so with an asymmetrical chamber. You have enough clearance to accommodate the batch size you want.

You need the right blower as well. My experience has been that the Ametek 122170-18 is the best you can use.

Additionally, you probably have too much shielding around your burner to prevent a good consistency of air and flame. Brush flame torches like the Gods BP’s, the Seiverts, Exacts are absolutely perfect for this. They won’t blow out.
 
tamarian

I do want to talk more about the heat issue. Do I need to move more beans? I feel like I am moving a small number of beans compared to the total bean mass and that may be part of the total issue. If it helps, I'm thinking in the theoretical sense. So what is it about a 20 pound roaster that allows the heat to stay lower? I feel like i'm not getting my question across correctly, but maybe you all will understand what i am after.

Is it an air volume issue? air pressure? cross section of beans moving?

One thought i had, is my perf plate hole density is a lot tighter then most of what i see on here.


The movement looks right for this size and design. Asymmetrical helps with larger batches. But if the roast is progressing fine, decently controlled and gives uniform color without roast defects then it is time to put some nice beans and roast them. See how you and others like the taste, compared to same beans on a different roaster.

Weld bulk, nails and any obstructions near the perforated plated can cause fires. Some beans can get trapped and collect heat until red. If there is little movement at the bottom left, increase the angle.

If spouting is stronger in one area, make sure the roaster is level, and seal any leaks.
Wa'il. 1 Kg PID'ed gas-fired fluid bed roaster, GS/3MPS, K10F
 
http://english.varietalcafe.com
pisanoal
tamarian wrote:


I do want to talk more about the heat issue. Do I need to move more beans? I feel like I am moving a small number of beans compared to the total bean mass and that may be part of the total issue. If it helps, I'm thinking in the theoretical sense. So what is it about a 20 pound roaster that allows the heat to stay lower? I feel like i'm not getting my question across correctly, but maybe you all will understand what i am after.

Is it an air volume issue? air pressure? cross section of beans moving?

One thought i had, is my perf plate hole density is a lot tighter then most of what i see on here.


The movement looks right for this size and design. Asymmetrical helps with larger batches. But if the roast is progressing fine, decently controlled and gives uniform color without roast defects then it is time to put some nice beans and roast them. See how you and others like the taste, compared to same beans on a different roaster.

Weld bulk, nails and any obstructions near the perforated plated can cause fires. Some beans can get trapped and collect heat until red. If there is little movement at the bottom left, increase the angle.

If spouting is stronger in one area, make sure the roaster is level, and seal any leaks.


Thanks for the reply! Really happy to have you on the thread.

So I'm not sure how far back you have read, but ive roasted 3 batches. The first 2 I had ti get the ET up to almost 700 F in order to get close to my intended profile. This doesn't seem right? So to your first comment, i guess i would say I'm not happy with how it controls yet.

I do have some issues with movement around the back left due to obstructions from the glass and mlunting hardware. The welds are actually really good. It was TIG welded at a fab shop, amd done really well so that shouldnt be an issue. I have however been thinking of soldering in a steeper angled plate at the very top (maybe an inch or so) of the angled plate to help get that back corner moving.

I definitely checked level on the roaster and continue to have the same issues, thin spout. Depending on changes i make to my perf plate, it moves from front corner to back corner to middle-ish. It also seems really high in order the get the beans moving.

I made a makeshift perf plat out if aluminum to test, its 1.5 inches wide, and has around 120 1/8 holes. I noticed your roaster seems to have a much more spread out perforation pattern for an even larger perf plate area. Do you think i need to try significantly less holes? My open area compared to cross sectional area is like 3.5 percent. Yours based on your drawings is like .5.
 
pisanoal
CoffeeInterest wrote:

Perf plate does matter, but less so with an asymmetrical chamber. You have enough clearance to accommodate the batch size you want.

You need the right blower as well. My experience has been that the Ametek 122170-18 is the best you can use.

Additionally, you probably have too much shielding around your burner to prevent a good consistency of air and flame. Brush flame torches like the Gods BP’s, the Seiverts, Exacts are absolutely perfect for this. They won’t blow out.


Really sorry, I completely missed this post. I really appreciate the feedback.

With your blower recommendation, are you suggesting I'm lacking in CFM or pressure? Just looking to compare my blower to the one you recommended.

I do have a good bit of shielding around my burner, but I'm not sure id say its too much preventing the consistency you are talking about. I could see having trouble maintaining heat that way? But I have plenty of heat getting to my air stream, and it does not seem to fluctuate wildly.
 
pisanoal
Update:

I ran lots of tests with different perf plate designs, flattened it out, more hole, less holes, bigger holes, etc.

Ultimately I decided to go with a stepped design (pictured below). Essentially, a 1.5" flat perf plate, and a steeper angle from the end of the original solid 45. This dramatically improved the speed at which beans are being returned to the perf plate. I still had issues with the back corner which was the result of two things.
1. Thermocouple Placement for bean mass. It was about 1.5 inches off the angled plate towards the back, but it extended almost all the way across the RC.
2. Geometry of the Square RC. I started realizing that there were several 6" square builds on here, but no one either finished, reported back, or hit their target bean load (it was always way less). If someone found different results, please point me to the thread. It seemed the only successful ones were circular. Since there are no "corners" I think that improves both bean loft characteristics, and return characteristics.
I temporarily added in a steep plate where the 45 plate meets the back wall. Not much change. Removed the TC and viola. That combination did the trick. So I'm going to a shorter TC and I'm going to move it up to the faster moving beans to keep from slowing down the back lower corner, and add in that steeper plate. I haven't roasted yet, because my mods are held in by duct tape... So ill need to make some semi-permanent modifications in order to do a roast test.

Photo attached of changes, original is in blue, red is proposed changes.
pisanoal attached the following image:
rc_changes_small.jpg
 
renatoa
You can use a flat TC, to not disturb the beans flow.
 
pisanoal
renatoa wrote:

You can use a flat TC, to not disturb the beans flow.


I havent seen a flat one, unless you,are talking about just the twisted wire ones. Do you have a link to one by chance?
 
renatoa
Yes, the naked junction, in a kapton foil sandwich, posted some days ago in other thread.
https://perfectpr...cts/tl0225
Actually, the link was just to ilustrate the concept, I am DIY mine using a higher temperature rating kapton, the posted model is 200 C only.
 
pisanoal
Thanks. I may try that. I have a shorter TC too
 
CK
Interesting concept with the flat TC, but be mindful it may be reading the metal wall temperature instead of the BT.
 
pisanoal
CK wrote:

Interesting concept with the flat TC, but be mindful it may be reading the metal wall temperature instead of the BT.



Yeah you would have to figure out a way to suspend it in the coffee bean mass at the angle the beans are moving i think
 
renatoa
I plan to test a sandwich consisting of an outer layer of kapton, toward the wall, a single layer should be enough to make the wall influence negligible, and an inner layer of copper, on top and in contact with junction, thus increasing the contact area with beans.
This way I hope to have the best approach to this difficult temperature picking scenario.
 
tamarian
I do want to talk more about the heat issue. Do I need to move more beans? I feel like I am moving a small number of beans compared to the total bean mass and that may be part of the total issue. If it helps, I'm thinking in the theoretical sense. So what is it about a 20 pound roaster that allows the heat to stay lower? I feel like i'm not getting my question across correctly, but maybe you all will understand what i am after.


I am more hands-on and find that taste trumps theory. Most theories on roasting are based on drums. Each roaster has its own characteristics. So it more important to see how does it taste?

Where did you place ET probe? Some locations may reach even higher if air flow is too high. With fluid beds you just need to initiate the circular movement and gradually decrease air flow as the roast progresses.

If you place ET probe above the beans, away from the air flow, it should not be much higher than BT. If below perforation it will a lot higher, depending on metal and thickness.

Getting rid of dead zones with steeper angle is crucial to taste (avoiding taste defects) and safety.

Adjusting perforation may help with efficiency, and possibly taste. But you need a reference point with taste, to see if any changes are worth it. But it may be easier to just adjust air flow as a starter.
Wa'il. 1 Kg PID'ed gas-fired fluid bed roaster, GS/3MPS, K10F
 
http://english.varietalcafe.com
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