Pollution controls is a timely topic but it was not at all planned for right now, another example of serendipity. We are currently upgrading Mel's ( freshcup.ca ) third generation Roastaire™. It is only five years old but enough new parts were developed in the interim that it was a good idea to modify or install parts to satisfy his working requirements. The first occasion for an "Ah Hah!" moment was the inside view of the exhaust just before it enters the chimney. It was a good feeling to have the proof that the "SmokEater™" was working so well.
The second element in this synchronicity is the chimney fire warning contained in two advertisements in the September - October "roast Magazine":
- If you're a roaster, you know the quote: "It's not IF you're going to have a roaster fire, but WHEN."
- "According to the U.S. Government, there were over 1,800 roaster fires last year." an advert by Iron Dragon Tools
They were advocating regular exhaust and chimney cleaning to prevent chimney fires yet the Roastaire™s roasted for over a decade without cleaning an exhaust nor having a problem. Furthermore, only days before we had witnessed a five year old Roastaire™, which roasted 5 days a week, that had an exhaust which was as clean as the day it was installed.
Further reading of "roast Magazine" showed the significance of the problem where their featured interviews asked each interviewee about their experience with fires. Youtube has some videos of the chimney coating problems faced by other roasting companies. Mel was deprived of this experience but he does not mind.
Originally our pollution test was only a visual inspection or rather the lack of visual evidence at the chimney when the Roastaire began the Cool Mode. The test is more stringent now but we did not have to make any changes to the roaster. Obviously a clear exhaust cannot be deemed to be a definitive pollution test after all we know that the common solution to neutralizing the smoke is to subject it to the high heat of a natural gas flame. Small independent roasters do not have the required scrubbers to clean the combustion residues but they do eliminate the roasting smoke. You still have to ask "Is the 400,000 btu to 1 million btu flame in the Afterburner the best way to eliminate smoke?". It seems to be very wasteful to me not to mention the pollution by that flame itself. In addition to its costly fuel charges the gas Afterburner takes up valuable floor space. We decided to make the SmokEater™ a standard component of the roaster to optimize its operation and to minimize the footprint. It does create a more expensive basic unit but we don't foster midnight roasting unless it is the third shift. Of course not having to pay the gas heating for those high input Afterburners means that savings accrue very quickly.
Another fundamental difference with Drum Coffee Roasters is that they are continually flowing air through the flame, through the beans, and then up the chimney. The Roastaire™ is a closed loop system for the entire Roast Mode. During that time the air is recirculated which has the added benefit of significantly increasing the heating efficiency. The air cleaning process wasn't an easy problem to solve. Leaving too much smoke in the circulating air can affect the taste of the coffee by coating the beans with a tar like substance plus coating the inside of the roaster with the same substance. Below is a photo of the air duct just before it enters the Roasting Chamber. After 5 years of roasting there is only a light staining of the interior of the duct.
A design choice was to stop the roasting process within the roaster to improve the roasting repeatability. Our earlier generations used a cooling tray, which is easier to accomplish, that delays cooling until the transfer is done and evenly distributed over the bottom. Cooling within the Roasting Chamber permits the constant monitoring of the air quenching of the beans which stops the exothermic roasting reaction within a few seconds. It also assures that the air entering the roaster during the Cool Mode will be "double cleaned" before it is evacuated to the vent or chimney.
California is the bellwether on emission standards but it is still a work in progress. The traditional method has been complaint based forcing many roasters to occupy commercial areas or midnight roasting. The people at Roastaire™ promote the "theatre of roasting" which takes place at the café. It is the most convincing way of communicating to clients that the coffee is "freshly roasted". To this end they roasted, without a chimney, on the floor of the Canadian Coffee & Tea Shows in Vancouver and last year in Toronto.
In closing here is a quotation that appears in the October 26, 2011 edition of the Edmonton Journal Food Section which describes one side effect of the technologies we supersede.
“When we moved from our old location to this new location, the first
couple of months we roasted coffee, I saw the fire department four times
because people driving by would see all the smoke from the roaster
coming out of the roof, and they thought the building was on fire,” says
Filpula, laughing. “The firemen would come in; I’d give a tour of the
roaster.”
