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The "Roastaire" Roaster
RDL

Quote

freshbeans wrote:

The blower for bean transport is a 3 stage, 7.2" ametek. ...
I was looking to see if perhaps they had created a 'hot loop' to maintain heat on one side of the roaster, while cooling the beans in the lower chamber with the ametek .

I don't see anything to support that, but it would be clever!
-Scott


Scott,
I am new to this forum but not to roasting. I might be able to confirm some of your analysis and explain where some people have drawn the wrong conclusion. Of course since this is a very public site not all questions will be answered since there are Trade Secrets in this business as well.

The graphics the members have attached are of the 4th generation 3 kg roaster.

The Ametek blower is used to pneumatically convey the roasted coffee to a Packaging Hopper. That sequence first starts with the Cool Mode when a Valve is opened to blast the roasting beans with 45 seconds of cool air. Generally it takes less than 10 seconds to stop the exothermic roasting process. The extra cooling makes sure that the beans are below 190?C. Another Valve opens to drop the roasted beans into the Dump Hopper. Both of those valves close which isolates the roasted beans from the roasting circuit therefore the Ametek pneumatically conveys the beans to the Packaging Hopper while the Roasting Chamber is loaded with green beans.

The beans are further cooled for say three minutes then the Ametek Cooling Blower automatically shuts off. The beans are then dumped into a tray for weighing. i259.photobucket.com/albums/hh296/RDL33/3%20kg%20Coffee%20Roaster/4bd149fc.jpg

To recap: yes the beans are initially cooled by the Main Blower because the lag time is lowest if the roasting reaction is stopped in the Roasting Chamber. The roaster itself does not lose much heat because the beans heat the air as part of the cooling process.
 
JETROASTER
RDL,
Thanks for jumping in! Feel free to introduce yourself, we're a decent bunch around here.

If you have any other offerings/pics/vids, they are always welcome.
No need to over-expose, but we're always looking to learn more. Thanks again, -Scott
 
RDL
Thanks Scott,

I am flattered by the level of attention this got. There were perceptive comments and some that missed the mark. Perhaps I will make a few clarification comments. The Main Blower is 3 Hp. You are correct that there is a Loading Hopper in the countertop surface i.e. no lifting of green beans over your head.

The function determined the look while design priorities focussed on timely roasting information, energy efficiency, and pollution controls. FreshCup.ca were the only people roasting inside the convention centre at the Canadian Coffee & Tea Shows in Vancouver and Toronto - without using a chimney or vent.

At home I use a modified Popcorn Pumper but when roasting 3 Kg batches a pollution control system is required unless being unpopular is a life goal. We felt that single pass air flow was wasteful but it is not an easy task to recirculate the air. Roastaire.ca does have more information about energy efficiency.

I lost out on the clear roasting chamber (it quickly gets gungy anyhow) and therefore had to develop other sensory inputs.

I am not certain about the "artisan reference" which is a discussion in itself. The roasting information is shown in "real time" and since we can "kill the exothermic reaction" usually in less than 10 seconds, the RoastMaster can call the roast with great accuracy and of course repeatability. On bigger roasters the roast has to be anticipated a long time in advance because it takes time to dump from a drum roaster plus they use cooling fans which are unable to push much air through the beans hence the mixing paddles. Many roasters use water spray to accelerate the cooling. Yes, we do give the RoastMaster better timely information in the same way that your car has a speedometer instead of a stopwatch.

The opinion part:
The artistry is knowing the optimum roast for a coffee bean, it is understanding blends, choosing the green coffee beans, turning out consistent roasts, making sure that the tools are performing well and recovering from "acts of god" and utility companies instead of giving excuses.

Raymond
 
JETROASTER
Thanks Raymond,
I was surprised the machine had never been discussed around here before!
The Artisan; I think there is always an urge to dislike automation....I'm just as guilty. At the end of the debate.... the art is in the artist, not the tools.

From a cafe biz standpoint, I must admit, I'd be the first to sign up for the automation. That machine plus a couple super-autos would address alot of the realities that come into play.
The vast majority of people that get hired do not have a deep passion for this stuff.
Consistency, speed, and training time are all real issues. Automation certainly has it's place.

Beyond those issues, the pollution control could be the deciding factor on whether or not a desired location is even viable!

Drum roasters have long had sexy machines to place in the front window...it's nice to see air-roasters coming out from the back room.

Hat's off! -Scott
 
RDL

Quote

freshbeans wrote:...Here's the question;
Let's say I roast #2 @ 70cfm with no recirc. Then I roast #2 @140 cfm with 50% recirc. I'd still put 70 cfm out of the stack.

Have I preserved any VOC's ? ... -Scott


All the air is recirculated which was a major design challenge because as everyone on this forum knows the air becomes smoke laden towards the end of the roast. We estimate about 85% of the smoke is eliminated at each pass which produces, our clients tell us, a clean tasting coffee that does not taste washed as in a single pass roaster nor do the beans taste like the smoky air was redeposited on the beans (giving the beans a mat appearance). I personally prefer the taste from the 3 kg roaster than what I get from my "single pass air" modified Popcorn Pumper.

Here is a picture taken of the tube leading to the Roasting Chamber if the Roastaire.ca after 5 years of roasting. You will note even less build up than single pass roasters. Darn it the URL is not coming through and the Attachment is not showing up in the Preview Reply.


Roast Magazine said that according to government statistics there were 1,800 roaster chimney fires in the USA last year. It appears that not everyone is making an effort to eliminate smoke. Generally the best we see is a huge Afterburner which replaces the smoke with the fumes of burning hundreds of thousands of BTUs.

I'll post this and see if the photo is shown.

Raymond
 
Dan
Raymond, If you preview the post you lose the attachment. Just trust and post!

So you are saying that some smokiness, 15%, is better than 0% or 100%?
 
RDL

Quote

RDL wrote: ... Here is a picture taken of the tube leading to the Roasting Chamber if the Roastaire.ca after 5 years of roasting. You will note even less build up than single pass roasters. Darn it the URL is not coming through and the Attachment is not showing up in the Preview Reply.
Raymond


Thanks for the posting directions. I'll try the attachment method.

DAN: "So you are saying that some smokiness, 15%, is better than 0% or 100%?"
Dan, I wrote that our "clients tell us" I also mentioned my preference of the 3 kg roaster vs. the Popcorn Pumper. This was not a design criteria it just fell in our lap when we sought to improve the energy efficiency. I am certain that Forum Members are aware of taste subjectivity. The roasting process is significantly different than drum roasters.
First of all, the air temperature is about 200?C lower in our NXT Roaster which means that the beans are not always "cooking on high". The higher air pressure (not flow) means that heat exchange is done through all the beans not just the first layer. A measure of the heat transfer efficiency is that our air temperature is 200?C lower yet we roast in half the time than a drum roaster. If our tests had shown that roasting twice as long was better we would do that. Likewise that cooling air pressure means that the exothermic is halted quickly.

In short, it is not only recycling of air that affects the taste.

Now let's try photo attachment option.

Raymond
RDL attached the following image:
body_valve_5yrs.jpg
 
JETROASTER
"higher air pressure (not flow)"

I've been chasing this for a few years! The pursuit has been to make a deeper bean mass with a more narrow distribution area....at higher pressure... to push thru.
I was always a bit turned off by the splashing bean mess I saw in the Sivetz machines. It struck me as all CFM and no pressure.
Would I be prying if I inquired as to the operating pressure below the distributor?
Thanks-Scott
 
RDL

Quote

freshbeans wrote: ,,, I've been chasing this for a few years! The pursuit has been to make a deeper bean mass with a more narrow distribution area....at higher pressure... to push thru.
I was always a bit turned off by the splashing bean mess I saw in the Sivetz machines. It struck me as all CFM and no pressure. ...-Scott


Scott, we are of the same opinion on air delivery. Of course, it has to be optimized not pushed to extremes. The NXT Roasters guideline was to fluidize the bed of beans which means that the air is flowing around all the beans. Since they are in suspension (think of the ping pong ball girations when in the vertical output stream of the vacuum cleaner) the beans will not rest on the hot metal for more than milliseconds yet they will not be shot around like a bean blaster. The problem is not getting the pressure but rather having a pressure that bridges the changing variables. Of course that pressure has to be mated to the appropriate Grid Plate and Roasting Chamber. I'll answer your question with .7 psi though there is flexibility in the system. In other words the beans decide (or if you prefer, it is the condition of the beans that largely decides the pressure), if they ride high the effective porosity increases and the pressure is lower while a small dense bean will create more restriction.

The pressure is within the range of a higher end vacuum motor but I wold not attempt to recirculate the air (been there in generation 1 and 2).

Raymond
 
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