topbanner.gif
Login
Username

Password




Not a member yet?
Click here to register.

Forgotten your password?
Request a new one here.
Shoutbox
You must login to post a message.

renatoa
03/25/2024 12:38 PM
coffee drink, Ramper?

allenb
03/24/2024 12:10 PM
Siam3D Welcome

renatoa
03/23/2024 3:02 PM
welcome cup, andrewg

allenb
03/21/2024 5:10 PM
TRH629 Welcome

allenb
03/21/2024 5:08 PM
marimohead Welcome

In Memory Of Ginny
Donations

Latest Donations
dmccallum - 10.00
JackH - 25.00
snwcmpr - 10.00
Anonymous - 2.00
Anonymous - 5.00
Users Online
Guests Online: 4

Members Online: 0

Total Members: 8,165
Newest Member: Ramper

View Thread

Who is here? 1 guest(s)
 Print Thread
Fans - Fluid bed Roasters
Ascholten
I know size is probably an issue here but volume seems to be what you want for airflow, the rotor on that centrifugal blower is rather small.
Why not go with a squirrel cage like a furnace fan? much quieter if noise is a concern, and they do come in various sizes. You can pulley them for any speed you want. heck you can hide the thing underneath the table and just duct work the airflow up to your project.

Just throwing out some ideas, not trying to tell you how to do your job or anything.

Aaron
 
Mike
Aaron,

You're right, size is an issue, I'm trying to build something with a relatively small foot print. I did try some squirrel cage fans and they get pretty large before getting the pressure I want without a tremendous amount of flow.

My shop area has recently reached the point where I can get some work done. So, I've been working on the bearing problem with the fan shaft - - I've burned up the ball bearings everytime I try to 'run them in' for six hours or so. :( Really getting tired of it :@ - so I'm re-machining that whole assembly for a 'little' larger bearings:

homeroasters.org/images/thread pics/bearings.jpg

I'm confident these will work. They are used in the spindle of a small milling machine that I have (it turns 10K RPM all the time). I'm also sure that they are considerably larger than necessary. Once I zero in on the required speed for the fan, I'll go to a set of pulleys (Dan mentioned the toothed belt style) and have to re-engineer this assembly anyway. I'll deal with bearings again then.

Mike
B)
Edited by Mike on 08/21/2007 10:29 AM
 
Mike
And then again, when I get this thing apart - - I don't think I'd have trouble with these bearings for my fan spindle!

homeroasters.org/images/thread pics/bearing.jpg

Mike
B)
Edited by Mike on 08/21/2007 10:28 AM
 
Dan
LOL! Only that it will take half your motor's horsepower just to spin it!
 
Mike
I think it'd take triple the power I've been working with to spin it very fast.

I was checking my local junk yard for aluminum stock yesterday and they had this X-Ray machine from a dentists office. Grin It was dis-assembled into major components and had all kinds of little do-dads and stuff. Cost me $20, I've salvaged a 10 Amp variac, a really accurate resistor array with a thirty six position switch, a couple of small Bodine gear motors and all kinds of other treasures. Loretta gets a good belly laugh s:8 out of the deal also - she can't believe the depravity of a serious geek. ;)

The bearings are from the base of the articulated column - interesting engineering.

Mike
B)
 
Mike
Well, I've finally got enough of my indoor shop finished (now that the weather is warm enough that I could have worked in the garage) to get a little work done.

I put together a new spindle assembly with the new larger bearings and made sure that there was no chance of mis-alignment. I bored for the bearings after the spindle housing was machined and assembled - permanently - JB Weld. Ran the bearings in for a total of 12 hours - running with no noticeable heat - - finally.

I'm getting plenty of pressure at less than the maximum RPM available with the step pullies. But not enough air flow. This isn't necessarily un-expected - - look at the small hole the air flow gets forced through between the fan and the base.

homeroasters.org/images/thread pics/New%20Fan%20008.jpg

The next configuration will be awkward, the long plate will hold the spindle, motor and fan arrangement, and will have to be vertical to accept the heater/roast chamber assembly. But seeing as how this is still a proof of concept prototype - - it should allow me to test things. The whole thing can be folded together in a later itteration.

homeroasters.org/images/thread pics/New%20Fan%20013.jpg

It does feel good to be getting something done on the project for a change. Although building the indoor shop has been fun also.

Mike
B)
Edited by Mike on 08/21/2007 10:31 AM
 
Dan
Mike, that is looking very good! You've learned a lot on this project. Remember, on centrifugal pumps, you have to have a minimum flow otherwise you will experience 'shutoff.' That is, as you begin to reduce your exhaust orifice, the pressure will go up as flow goes down, but at some point the pressure will begin to drop drastically. That is shutoff. At that point you will want to increase the orifice. To reduce flow further, reduce rpms.

What are your thoughts on recirculating heat?
 
Mike
Dan,

I have been considering some kind of a small recirc flow path or waste gate arrangement to deal with shut off head. I've dealt with this issue with fluid systems before but it's new ground for me in an air system. I've got a couple of electronic Heise gauges that go down to hundredths of a PSI and can do ΔP measurements, so I should be able to cobble together some flow measurement arrangement. This project has turned into a real learning experience - I'm really enjoying it.

Recirculating heat. Like minds...etc.

I've got a half dozen drawings in the project sketch pad. The fan etc. being seperated from the motor, and the belt arrangement being easily seperated and sealed from the recirc flow begs the recirc arrangement. I don't think it would be too difficult to recover somewhere in the neighborhoold of 20% (possibly more) of the heat with a simple heat exchanger on the exhaust stack. Direct recirc would introduce roasting oil fumes etc. back into the system but a really simple copper plate finned on both sides with the exhaust and intake seperated between the sides should be efficient enough to make the effort worthwhile.

Mike
B)
Edited by Mike on 04/23/2006 5:50 AM
 
Mike
I'm starting to get back "into" this project. I even got some work done today along with the obligatory Sunday yard work. Grin

homeroasters.org/images/thread pics/New%20Fan%20017.jpg

This thing is really getting stretched out, I don't want to have to re-machine everything because I need more real estate. :@

Mike
B)
Edited by Mike on 08/21/2007 10:31 AM
 
Mike
One step closer.

homeroasters.org/images/thread pics/New%20Fan%20020.jpg

Wedged the thing into a vertical position and strapped a P1 heater/roast chamber assembly onto it and it provided plenty of air - pressure and volume - at the second fastest belt position.

Next step is to build an assembly that I can clamp to the side of my workbench that will allow the prototype to rotate 180 (upside down) to allow unloading the beans. I'll mount the heater/roast chamber in a more secure fashion. I'll hook up an extra PID to it and roast some coffee.

Weaknesses so far, as I see it:
A. Fan is still making more noise than I want.
B. Fan requires more speed than I'd like.

I believe that when I set up the fan with a discharge volute it will increase the efficiency enough to allow slowing down the fan a bit. I've had trouble finding definitive information to allow the math for this but a WAG based on what I've been able to find makes me hope for around a 15% increase in efficiency on the pressure side of things, which should be plenty.

The hoped for decrease in speed (previous paragraph ) will help the noise situation. The fan housings are currently thin (about 24 gauge) stamped stainless and were obviously originally engineered without a major consideration toward sound deadening.

I figure that the second stage discharge volute will be machined from aluminum plate. The seperator sheet and return static impeller (discharge of first stage to inlet of second stage) and everything else associated with the fan will also be machined out of fairly substantial material. The whole assembly will be housed in a piece similar to the current large tube fan exhaust. Hopefully these measures should substantially decrease the associated noise. Enough for tonite. It's late.

Mike
B)
Edited by Mike on 08/21/2007 10:32 AM
 
PaulM
Hi Mike,

Have you considered using one of those freshroast chambers to avoid having to tilt the whole device in order to empty the beans?

Paul
 
Mike
Paul,

Like minds..........

In its present configuration I'm just going to do something temporary so I can tell myself that I know it'll roast coffee (that I'm making progress).

In it's final configuration (in my dreams) I have a removable roast chamber / chimney fitted to it. As with the rest of this project I have everything in a firm prototype stage......trying to work my way past it in some areas. The prototype roast chamber / chimney currently looks like this:

homeroasters.org/images/thread pics/Chamber,Chimney,Clamp.jpg

The only reason I'm using the P1 assembly for testing is that it doesn't require any extra machining to fit it to this assembly and if all my figures work out - it should present approx. the same pressure differential as the final product.

Mike
B)
Edited by Mike on 08/21/2007 10:33 AM
 
Dan
Mike, A lot of the noise is coming from the blower's inlet. You could add a sound baffle, or some sort of air filter material to help reduce that. Also, use some hose clamps to hold some rubber sheeting to the blower's cylindrical housing. Dan
 
Mike
Dan,

Good thinking s:2

I'll try both suggestions. Grin

Mike
B)
 
Dan
Mike, Inlet mufflers are common practice on compressors and vacuum pumps. I put a 'girdle' on my vertical compressor tank and it quieted the noise a little. The tank was reverbing with the pump.

Your project is shaping up! No one could say you put things together with bailing wire and duct tape!
 
Mike
Dan, you may want to rethink you're comment:

>No one could say you put things together with bailing wire and duct tape! <

After looking at this: homeroasters.org/images/thread pics/Assembly.jpg

It's starting to look like a plumbers nightmare. The mount gets it into the correct geometry, allows me to turn it completely upside down and I can lock it at whatever angle I want, so it satisfies its design requirements.

I've still got to machine a phenolic spacer to place between the roast chamber and the rest of the assembly to allow bringing the heater leads outside and do some heat transfer limitation. I've also got to install a fitting for the TC.

Seems like my progress recently is at a snails pace - just got to keep it moving.

Mike
B)
Edited by Mike on 08/21/2007 10:34 AM
 
Mike
As usual it turned out to be a little more complicated than just making a phenolic spacer. I had to turn an aluminum adapter, two phenolic spacers (wires to heater sandwiched between them). I mounted the TC the same way as I usually do in an "Ubber Popper" buildup. I had to drill out the three mounting holes for the roast chamber and secure it to the adapter plate with cap screws. I'm making sure I don't destroy the P1 roast chamber because I end up building a roaster for someone every couple of months and haven't kept my stock of P1s up to my normal 3 or 4 extras - they seem to be a bit harder to find recently. If this all works out (roast coffee) I'll start playing with the upgraded, double sized roast chamber next. I've got to do some planning before I revisit the fan end of this project.

Mike
B)
Mike attached the following image:
AdaptedChamber[39].jpg
 
Mike
Well, I nailed everything together and tried it. Some success, and some not so much.

My normal load in the 'Ubber Popper' is around 280 gms. Seeing as how I am using the same roast chamber I figured that would be a good place to start. Unfortunately the fan speeds available with the step pulleys gave me a little too much or not quite enough air flow for that load. I decided to go with the higher flow rate, so I tried to manipulate the load to deal with it. I prefer to roast with the chamber tilted so I get a good smooth circulation, I tilted just enough to establish low side going down and high side going up bean circulation (about 7? off of vertical). 400 gms seemed about the right load:

homeroasters.org/images/thread pics/First%20Roast%20001.jpg

Obviously I don't have variable speed with this fan currently. Variable air flow has a lot to say for it when controlling a popper based roaster. I replaced my standard 10" chimney with a 14" Bake-A-Round tube in preperation for overflow from the larger load and excess air flow when the beans lighten up. I also pre-staged my heat gun to supplement the heater if necessary (all the extra air flow makes the roaster considerably less efficient, heat wise). So time to load it up and roast:

homeroasters.org/images/thread pics/First%20Roast%20002.jpg

The bean circulation worked well from beginning to end, without the expected blowing the beans out the top late in the roast. I didn't force the PID to relearn this new configuration so it lagged the program by 15? F or so, but maintained well enough - early in the roast.

homeroasters.org/images/thread pics/First%20Roast%20003.jpg

The heater started showing its limits at around 350? F and couldn't keep up at all above 385? F. By this time I was behind the profile programmed into the PID. Rather than juggle the profile, I started supplementing the heat by feeding the fan inlet with the heat gun. This worked out better than I expected and I ended the roast at hint of second at 442? F. Insulation around the roast chamber as in the 'Ubber Popper' would help this heat problem, but probably not enough. An extra couple hundred watts of nichrome heater element would do it, I'm confident. Turning a set of pulleys to give the fan the right flow rate for a smaller load (around 350 gms) would probably do the trick also. This is still a work in progress and the goal does not include the P1 roast chamber or this fan motor, so I doubt if I'll persue a fix for the inadequate heat. It does tell me that I'll have to do a little engineering toward a fix as I progress.

Mike
B)
Edited by Mike on 08/21/2007 10:52 AM
 
Ascholten
Ok, I don't know much about your put together here but a few comments / possible concerns.

You started feeding the fan inlet with the heat gun. Can the fan withstand that kind of temperature? Some motors / blower assemblies rely on the incoming air for cooling. Feeding hot air might cause premature failure.

However on that, if this is NOT a problem, and since the beans blowing out don't seem to be a problem either, have you considered possibly a Y connection on the exhaust and port some of it back to the inlet kind of like a recirc line? Get some of that hot air back into the process so it's not 'wasted energy'. Since some is still blowing outside, the smoke will still get vented properly.

Just a thought.
Aaron
Bean there Done that, donated the T-shirt to the Church of the Second crack.... St Beanyface
 
Dan
Sounds like a success, to me! Ya know, you've replaced all the original P1 components except the heater. And now you have having heater problems. Why not go all the way and replace the heater, too?

Something I've kept my eye on are the heat gun replacement cores for industrial heat guns and heat blowers. Check out this page at Grainger:

Heat gun elements:
http://snipurl.co...

Just had to help out here :) PeterZ c:3

In particular, check out the heat blower elements that are 14 Amp (1A505) and 18 Amp (1A506).

Dan
Edited by peterz on 05/18/2006 10:23 AM
 
Ascholten
If you do go the heater element pre fab route as mentioned above, make sure you pay attention to the voltage so you don't end up with a 220 Volt element being fed from 115. The watts just don't quite add up that way Grin

Aaron
Bean there Done that, donated the T-shirt to the Church of the Second crack.... St Beanyface
 
Mike
Dan,

good find:

>In particular, check out the heat blower elements that are 14 Amp (1A505) and 18 Amp (1A506).<

I think I'll order a 1A506.

I'm cogitating about how to configure and machine a volute for the fan (someday I'll have a small CNC mill). When I solve this it should allow 'folding' the fan assembly 180? and place it alongside the heater / roast chamber housing. I wish I could find some good information on how to size the volute correctly vs flow rate etc.

In the mean time I'm going to work on cobbling together the larger removable roast chamber and configuring the larger heater. I still think that if configured correctly the heater could present much less flow restriction and allow the fan to run slower (and quieter). buying a pre-sized heater will help - I may find that I'll remove the coil from its fixture and come up with a new geometry for it.

Down the road after everything is functional I will address some heat recovery and hopefully that will get things back below 1500 watt power drain. I was surprised how little heat I had to add with the heat gun to finish the roast - made me feel positive about heat recovery / recirc.

BTW, I've driven the fan 'direct drive' with a brushless DC motor with success. Used a variac and bridge rectifier / capacitor for power supply with variable speed. It cut out a fair amount of noise associated with the step pulley arrangement and, of course, good speed control. It is a shame that these things are so expensive if purchased new. The stuff I'm using is fairly reasonable from surplus or Ebay sellers - unfortunately this is not conducive to replicating the machine if it is successful.

All in all - I'm pretty happy with the progress. And I get an occasional, really good belly laugh when I look at the assembly and then look at the 'Ubber Popper'. If I keep going this way I'll need a two wheel trailer to move the thing - - it keeps getting bigger. ;)

Yes - just a lighter shade of blond - I like that - we ought to write a song.

Mike
B)
Edited by Mike on 05/14/2006 12:57 PM
 
PaulM
Look great Mike.

Thinking about your prototype roast chamber, do you think you'll have to change placement of TC or adjust your profiles when you get it in place?

Paul
 
Mike
Paul,

I'm planning on the TC probe going up through the bottom of the removable roast chamber so the probe will stay with the assembly and allow the chamber to be lifted up and out of the fan/heater/control/housing assembly.......most of this is in my dreams, so far.

I'm sure I'll have do to some program manipulation if I drive this thing with a PID. The Fuji does a good learning trick on its own. My actual roasting profile is pretty much of a fluid thing - different beans, different blends etc. I learn a few new tricks periodically (I always listen to Les ;) ). I would expect the new machine to give me the same roast as I get from my 'Ubber Popper'.

If everything works out (and I live long enough ) , the advantages should be:
Quieter - easier to hear 2nd, two to three times the roast quantity, Removable roast chamber assembly - instead of having to man-handle the whole machine when 'dumping' the roast,
In-machine cooling - as quick as collandar/fan (target 2.5 minutes to ambient),
Single housing in a kitchen friendly configuration,
Possible heat recovery/recirc,
got an idea for chaff collection
etc. etc. etc.

I'm trying to modularize the effort. This fan module has taught me a lot so far, and I'm going to have to revisit it. I've got a little bit done, or at least some fairly detailed plans for each of the other modules. And I'm sure that everything will have to go through some changes when I try to do a final blend of bringing everything together.

I know I'm getting awful anal about this effort, but what the hell.. Shock ..I'm enjoying it, and learning a lot.

Mike
B)
Edited by Mike on 05/15/2006 10:55 PM
 
PaulM

Quote

Mike wrote:

I know I'm getting awful anal about this effort, but what the hell.. Shock ..I'm enjoying it, and learning a lot.


Nothing wrong with that. You mentioned CNC, and that plus this comment reminded me of this:

http://www.rcgrou...ge=5&pp=15

Look at the post from Planeman on 10/15 at 1:20pm. I saw a little of myself in that. ;-)
 
Jump to Forum:

Similar Threads

Thread Forum Replies Last Post
19th Century US roasters MY FIRST ROASTER 11 03/26/2024 10:13 AM
Square tube fluid bed Fluidbed Roaster 5 02/26/2024 9:32 AM
Roasters Pal app (iOS and Android) ROASTING SOFTWARE APPS 6 01/19/2024 10:13 PM
First Fluid bed test..Some success, many questions MY FIRST ROASTER 14 12/23/2023 11:13 AM
Drum or Fluid Bed Building a Coffee Roaster 6 12/04/2023 1:06 PM
Homeroasters Association Logo, and all Content, Images, and Icons © 2005-2016 Homeroasters Association - Logos are the property of their respective owners.
Powered by PHP-Fusion Copyright © 2024 PHP-Fusion Inc
Released as free software without warranties under GNU Affero GPL v3
Designed with by NetriX
Hosted by skpacman