Fluid bed Temperatures

[kevsnova]

What is the desired range of exhaust temperatures in a fluid bed coffee roaster ?
The roaster I made has a set temp of 220 degree fahrenheit with the burner on low  2 psi gas flow with air blower on.
On high setting, it can climb to 600 degrees in about 5 seconds if left on 5 psi gas flow. So my question is, how slow or fast do I need to have the temp change and what would be minimum and maximum temperature range ?

Thanks...

[Ascholten]

There is so much to roasting that flue gas temp is only a tiny part of the whole process.

How big is your flue, how many BTU's do you put in there?  How many CFM are you blowing through?  How many lbs of beans are you roasting at a shot?

What would be more important is bean temp, not so much the exhaust temp as that can be affected by other things.   The roast process itself can change the temp gradient.   When I start out on my CFB the temperature split between air temp and bean temp can exceed 100 degrees or more, as  the roast proceeds on, that split can drop to 30 degreees.  The amount of airflow can change that too.   

I think you would be better off comparing inlet to the bean air temp (after it's been heated) and bean temp to watch the progression,  this can tell you if your roast is stalling and you need to put a little more heat on it.

Aaron

[kevsnova]

I have a 5" roast chamber with 430 cfm blower my roaster will roast max 4.4lbs  two  kilo with no issues.
I can modify my orifice and or gas pressure to give me a temperature (exhaust only testing) suitable for a fluid bed roaster, What I m looking for is what should be the lowest and highest temperatures so once I have a pid added it will make a smooth progression through the temp range.