As our small business outgrew its vastly overworked pair of table top roasters, we first considered buying a larger used roaster. However, we were increasingly concerned about the quantity of smoke that roasting coffee produces.
The standard approach to smoke control has been to put in an afterburner that incinerates the smoke at +1200F temperatures, often using more fuel than the roaster to accomplish this task. In the face of rising fuel prices and climate change, trading cleaner air for significantly higher fuel consumption seemed like making the best of a bad bargain. We wanted a win-win solution.
We knew about catalytic exhaust burners (which allow combustion at reduced temperatures) for pollution control, but hadn't heard of that technology being applied to coffee roasters. When we came across information about the Revelation roaster from US Roaster Corp, a trip to Oklahoma City to look it over was quickly arranged. Its combination of a catalytic burner, hot-air recycling, computerized control system, and the added fuel economy of a drum roaster over the air roasters we had been using, convinced us to go with a new machine. We've named her "Mo' Jo" and she's the first of her kind in Canada.
The roaster's secret is in the big black tower. The hot air, smoke, and coffee chaff are removed by a blower from the roasting drum and shot over into a cyclone located in the mid-section of the tower. The swirling exhaust stream in the cyclone allows the chaff to fall to the bottom of the tower while the gasses and smoke particles go up. There, the electrically preheated catalyst burns over 90% the smoke, adding the heat of combustion to the air stream.
At the top of the tower is an electrically controlled damper box. The roast master can chose to route the hot air back to the firebox of the roaster (conserving heat and fuel) or vent excess heat up the chimney. (In the future there will be a third option to put the hot air through a heat exchanger to capture that energy for space heating. The damper box is built into the tower, but US Roaster Corp hasn't started offering the heat exchangers as yet.)