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Propane Fluid Bed Roaster Design
jfern
Top  #51 Print Post
Posted on 12/09/2024 9:16 AM
Thank you for the feedback wbbh! I did not anticipate how much guidance I would need on this project. My present concern is that I may have too much heat loss as noted by allenb. However, I am using a 50,000btu burner that is overpowered to begin with, so maybe I will just need to turn up the fire.
 
allenb
Top  #52 Print Post
Posted on 12/09/2024 11:09 AM
Good point on not causing any hindrance for air getting to the venturi inlet of the burner. Regardless of what is chosen for the design, one thing to avoid is placing the burner flame ring portion of the burner at a point where air velocity is highest as depicted in all three designs in post #47. Where the burner is located, there is a reduced open area for blower air to slide past the burner rim which will cause a velocity increase and too much turbulence at the flame. It could possibly work but would require testing to see if that particular burner can handle it.

The semi-circular baffle in post 49 might work but I would eliminate the baffle separating the burner from the blower area, not needed.
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
allenb
Top  #53 Print Post
Posted on 12/09/2024 11:13 AM

Quote

jfern wrote:

Thank you for the feedback wbbh! I did not anticipate how much guidance I would need on this project. My present concern is that I may have too much heat loss as noted by allenb. However, I am using a 50,000btu burner that is overpowered to begin with, so maybe I will just need to turn up the fire.


I agree that even with heat losses, you'll have plenty of heat for the task. In retrospect, if heat is a problem for you on the exterior of the enclosure, you can add a little insulation and a thin sheet metal skin over it.
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
jfern
Top  #54 Print Post
Posted on 12/09/2024 1:56 PM
Thank you for the reminders about air pressure and turbulence at the burner head and venturi. Taking into account these accommodations, do you think this model would work?
jfern attached the following image:
update.jpg
 
allenb
Top  #55 Print Post
Posted on 12/09/2024 2:25 PM
Looks good to me! I'm assuming the metal structure supporting the gas entry fitting doesn't stretch across the venturi air inlet disc of the burner?
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
jfern
Top  #56 Print Post
Posted on 12/09/2024 3:16 PM
Good reminder, allenb! I haven't fabricated the bracket yet, but I will make sure it doesn't obstruct the air inlet disc. Thank you for your patience and willingness to workshop these concepts with me! Just short of asking you to design the roaster for me, do you have any other considerations for making this project a success? Thank you!
 
wbbh
Top  #57 Print Post
Posted on 12/10/2024 6:40 AM

Quote


I like example 2 or 3 above, the example here looks like it will not allow an adequate flow of air to the intake port on the burner. The burner is designed to work in atmospheric pressure, so the entire burner needs to see the same pressure from your blower.. With increased air pressure, more gas can be consumed efficiently.


This.
 
jfern
Top  #58 Print Post
Posted on 12/10/2024 9:03 AM
Thank you for the suggestion wbbh! I made some modifications to the image from post#47 to #49 to include your previous recommendation along with insight from allenb. Do you have any thoughts about whether #49 is a useful concept? Thank you.
 
jfern
Top  #59 Print Post
Posted on 12/10/2024 9:06 AM
Sorry, I referenced the wrong posts! I meant to say, I made design changes from posts #49 to #54 to include recommendations from you and allenb. Does #54 seem to be a useful concept? Thank you.
 
wbbh
Top  #60 Print Post
Posted on 12/11/2024 7:08 AM

Quote

jfern wrote:

Sorry, I referenced the wrong posts! I meant to say, I made design changes from posts #49 to #54 to include recommendations from you and allenb. Does #54 seem to be a useful concept? Thank you.


54 is ok if all blower flow is all through the section that contains the burner.

I'd also consider mounting the blower vertically and pointing the discharge away from the burner. The flow would hit the enclosure and flow back over the blower to beep the motor cool and possibly send a more even flow over the burner.
 
jfern
Top  #61 Print Post
Posted on 12/11/2024 8:35 AM
I am trying to conceptualize what a vertical mount would look like. Are you suggesting something like the attached image?
jfern attached the following image:
update_2.jpg
 
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