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Topic: Convection and Conduction ---> was: HG: air roast or drum roast? (5 msgs / 148 lines)
1) From: Eddie Dove
Good post, RayO.
I also found the following article to be a good read pertaining to the
subject ...
Vita non est vivere sed valere vita est
Roasting Blog and Profiles for the Gene Cafehttp://southcoastcoffeeroaster.blogspot.com/On Nov 8, 2007 6:08 PM,   wrote:

2) From: Lisa Carton
thanks eddie-----good article---
  recently i began using a blow dryer to eliminate chaff in my drum-----i would sinply lift every so often to see if it was building up then lift quickly and blast it out----it never significantly lowers the temp and it makes it MUCH easier to smell the real coffee smells of the roast progressing.....But the BEST part: since i started this i have been getting feedback that the coffee is BETTER too!!!! So i particularly was struck by the part of the article that mentions carcinogenic chemicals from the chaff burning sticking to the beans!  Makes sense to me!
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3) From: RK
I drilled a hole and mounted a 1/2" bolt that I drill out to accept a
thermal probe with the very tip having a small hole just so the bead of
thermal probe would slip in but not out. Since testing with the digital I
found out that I really liked the analog thermometer better. Lately with the
recent talk about air flow and chaff in the drum roasters I have been using
this inlet hole to blow air thru the grill and as it is located just off
center from the drum it works great to shoot a blast of air every couple of
minutes, by means of a air tank I already had. It does a good job of blowing
the chaff out of the drum and the grill, and raises the temp just a bit with
short blast.

4) From: Justin Marquez
Ron -
What do you think is causing the temp to go up with the air blast into the
drum? The chaff igniting when it gets out of the drum into the flame area?
Sweeping some of the hotter air outside the drum into the drum?
Safe Journeys and Sweet Music
Justin Marquez (CYPRESS, TX)
On Nov 9, 2007 8:47 AM, RK  wrote:

5) From: RK
This is a multi-part message in MIME format.
the drum? The chaff igniting when it gets out of the drum into the flame =
area?  Sweeping some of the hotter air outside the drum into the drum?
I have my analog thermometer right beside the inlet I blow air thru. I'm =
suspecting that the blast of air move the hot air in the grill around =
and raises the temp on the thermometer but probably the grill itself =
does not raise that much but with added 02 is does give the flames some =
added air and they do raise a bit, and with convection hot air it  =
raises the temps on my thermometer slightly,  but with just a short =
blast it should only be temporary at best.
But with a slow amount of air flow it should help in the roasting =
process much like the Dietrich.
I talked with a roaster here in town who roasts with a 12Kilo Dietrich =
and he said that with the air control lever in one  position  there is =
25% air flow thru the drum and when he dumps the batch into the cooling =
tray or flips the lever another position it puts 75% air to the cooling =
tray and 25% thru the drum. And in another position he can blast the =
drum with 75% air to blow the chaff out of the drum.
I guess the blast I run thru my drum and grill is such a small blast =
adds 02 to the fire and gets it slightly hotter then it just stirs up =
the heated air and that is why the temps rise a bit.I have noticed after =
the blast even with the burners on low to med that the flames get higher =
and sounds like it does when the grill is on high for 10 sec or so.
 It does blow the chaff out of the drum and even out of the grill thru =
the exhaust at the back.
Still experimenting

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