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Cheap LPG burner
progen
Top  #1 Print Post
Posted on 11/14/2024 7:42 AM
I'm currently running an electric heater setup going a little over 8000 watts at 240ish volts when all out. Roasts around 2 odd kg in my home built hot air roaster. Was thinking of winding 2 x 5000 watt coils for more power if needed but that'll require wiring and breaker upgrades so I thought of going gas.

Will something like this mounted in a plenum with the flames facing the incoming air work for a hot air roaster?

i.ibb.co/VLnYSdG/Screenshot-2024-11-14-21-28-13-001-edit-com-shopee-my.jpg

That's just them running at idle. It's a high pressure burner capable of higher output.

i.ibb.co/km3H6xL/Screenshot-2024-11-14-21-29-03-822-edit-com-shopee-my.jpg

i.ibb.co/R4J7Hb3/Screenshot-2024-11-14-21-29-24-221-edit-com-shopee-my.jpg
 
jfern
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Posted on 11/14/2024 11:16 AM
Some sources indicate it requires about 7,000 to 10,000btus (roughly 2,000-3,000 watts) of heat to roast a pound of coffee in a fluid bed roaster. I am building a roaster with a similar burner to the one in your image. The specs (50,000btus) seem to indicate it is adequate for my 1.5kg capacity, and could be enough power to roast up to 3kg. However, I don't see any builds referencing this style burner in a fluid bed roaster, so I guess we are in uncharted territory.
jfern attached the following image:
burner_5.jpg
 
progen
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Posted on 11/14/2024 8:13 PM

Quote

jfern wrote:

Some sources indicate it requires about 7,000 to 10,000btus (roughly 2,000-3,000 watts) of heat to roast a pound of coffee in a fluid bed roaster. I am building a roaster with a similar burner to the one in your image. The specs (50,000btus) seem to indicate it is adequate for my 1.5kg capacity, and could be enough power to roast up to 3kg. However, I don't see any builds referencing this style burner in a fluid bed roaster, so I guess we are in uncharted territory.


I estimate the burner, a tank of LPG, the regulator and some bits and pieces to come up to around USD50 so I guess it's something I need to experiment for myself.
 
progen
Top  #4 Print Post
Posted on 11/20/2024 11:11 AM

Quote

jfern wrote:

Some sources indicate it requires about 7,000 to 10,000btus (roughly 2,000-3,000 watts) of heat to roast a pound of coffee in a fluid bed roaster. I am building a roaster with a similar burner to the one in your image. The specs (50,000btus) seem to indicate it is adequate for my 1.5kg capacity, and could be enough power to roast up to 3kg. However, I don't see any builds referencing this style burner in a fluid bed roaster, so I guess we are in uncharted territory.


Back to this again. I'm not familiar with BTUs since I've never built a gas powered roaster before but the watts thing is definitely off. My slightly past 8000 watt machine can do 5lbs when cranked full.
 
allenb
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Posted on 11/20/2024 12:57 PM
I've found from limited experience that 1800 watts will do a lb. charge. 2kw would give some headroom. When building fluidbeds for larger capacities than 1 lb, it requires less wattage/lb as you increase batch size. Not sure where one would look for the tables that show that relationship but when you reach 5 lbs batch size, it's definitely not going to need the full 10KW.

To convert BTUs to KW, divide the BTUs by 3.41
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
progen
Top  #6 Print Post
Posted on 11/23/2024 2:52 AM

Quote

allenb wrote:

I've found from limited experience that 1800 watts will do a lb. charge. 2kw would give some headroom. When building fluidbeds for larger capacities than 1 lb, it requires less wattage/lb as you increase batch size. Not sure where one would look for the tables that show that relationship but when you reach 5 lbs batch size, it's definitely not going to need the full 10KW.

To convert BTUs to KW, divide the BTUs by 3.41


There's also an extremely important factor which is design efficiency. In the smaller 1kg prototype, I could get beans to first crack in 6 minutes like a small sample roaster because hot air filled most of the smaller diameter roasting chamber whereas in the larger 3kg capable one using the same 2" air inlet, because of the larger diameter cylinder, hot air only covered about 50 - 60% and I needed a higher turnaround rate which then necessitated higher heater power.
Edited by progen on 11/23/2024 12:55 PM
 
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