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Yet Another 250g-500gm FB Roaster
PhilH
Top  #26 Print Post
Posted on 12/15/2015 3:57 AM
Finally got a youtube vid posted
Sumatran Mandheling 750gm green, 640 gm roasted

got the Artisan Scope "READ" working finally with aArtisanQ_PID running standalone

there is a small overshoot at the start but pretty good after that
 
allenb
Top  #27 Print Post
Posted on 12/16/2015 9:31 PM
Wow, ask and receive! You've built in some very nice systems with this roaster and all seem to work very well. I especially love the control console. Nice touch!

I'm also very impressed with bean movement. It's not always easy to get a large enough mass to travel upward together and can end up being a very thin spout. When this happens, trying to increase bean flow only causes the measly spout to shoot higher without really improving bean flow. Your's is ideal. Great job!

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
JackH
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Posted on 12/16/2015 11:51 PM
I agree, nice work Phil!
---Jack

KKTO Roaster.
 
PhilH
Top  #29 Print Post
Posted on 01/03/2016 4:09 AM
I have been experimenting with a number of different origin beans and working through the roasting profile learning curve and Ive made some good progress. I have been referencing against my favourite locally roasted beans from the major commercial roasters here in Auckland. I have moved from "very average" to "drinkable" to "very good" roasts and have greatly benefited from Scott Rao's excellent book "Coffee roasters companion".

Im loving being able to repeat a great roast with the aArtisanQ_PID/TC4/Clippard profiling setup and have it come out pretty much exactly the same.

Many thanks to the homeroasters community for all of their support and generosity in making their efforts available to all of us - special thanks to Brad (greencardigan) for aArtisanQ_PID

I have been trying to increase the load capacity to 1kg as I have an event coming up which requires a LOT of coffee to be roasted.

I ran into some difficulties - the LPG gas burner didnt quite have enough power for 1kg and I didnt want to crank up the regulator on the LPG bottle much above 30psi. I have already drilled the orifice on the mushroom style camping burner from 0.35mm to 0.4mm (0.0157") and so I went for the next size up - 0.45mm. I also added a flame viewing window to ensure I can see the flame while roasting

Unfortunately what I saw was a horrible dirty yellow flame ! arrrgghhh !
sure enough it was sooty and weak - not enough air through the venturi for a good air/fuel ratio.

I was resigned to the prospect of replacing the burner / jet and reverting to 0.4mm but I have since had something of a eureka moment.

The orifice/jet mounting casting is screwed to the venturi tube / Mushroom Head assembly. I was able to use a couple of washers to pack it out approx half a mm or so which significantly increases the size of the air intake cross sectional area - Voila ! Clean Blue flame and huge maximum heat available.

AllenB may correct me with his BTU calculator but I believe I have as low as 1.3kW/4375btu/hr@5psi and as high as 8kw/27,300btu/hr@31psi. It will be a little less given the backpressure in the burner chamber. I can adjust the regulator on the bottle for different load sizes from 250g to 1kg to ensure the PID output is in a nice middle of the range sweet spot.

I cant easily go above 1kg as I will lose too many beans out the top in my current configuration and the bean spout/flume shape gets a little ragged
....... maybe I can extend the roast chamber higher

next job - make a damper of some sort to get more air flow through the cooler as the back pressure from the roast chamber diffuser plate is restricting the airflow when cooling which is a problem

This home coffee roasting is just about more addictive than the caffeine ???
 
allenb
Top  #30 Print Post
Posted on 01/03/2016 10:51 AM
According to the BTU calculator I'm using which is from Ron Reil's burner design site, 5 psi propane through a burner orifice of .0177" (.45 mm) will give you 9,194 BTU's/HR and at 30 psi will give you 22,521 BTU's/HR.

Accounting for a typical roasting chamber pressure of 10" HG (.3 psi) I would estimate it dropping to around 8,900 BTU's/HR and 22,400 BTU's/HR.

Glad to hear you were able to increase your air/fuel mixture without a huge effort! The burner viewing window helps a lot in my experience as well.

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
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