A Coffee Roasting Facility in the Southern part of the United States needed to review and analyze their existing Emission Control System for the off-gases from roasting coffee beans. After visiting the site it was found that the existing system used a catalytic oxidizer section that continued to fail due to high temperatures, coating from high boiler condensables, and high fuel usage when the VOC emissions were not present.

Coffee roasting process runs in cycles that average about 6 minutes and the VOC’s are emitted in very high concentrations for about 1 minute of that cycle. Then there is setup time for the next cycle, during which time the oxidizer is still running, and the next 6 minute cycle starts again. In addition to large temperature swings and high VOC spikes, there are also particles that are emitted and hydrocarbons which condense on everything in the airstream and require constant maintenance. The ductwork continues to develop a crusty coating which in many cases need to be scraped off; this application was quite a challenge to design a system to meet all of the requirements and make the customers life easier.

The base technology used is 2- 6,000 scfm two bed regenerative oxidizers to replace the catalytic oxidizer; the customer was expanding their operations. The choice of the regenerative units saved them well over $500,000/year in operating costs. And from an Environmentally Green standpoint; they reduced CO2 emissions by 1,030,000 pounds per year per roaster. A cyclone was used to collect any particles that got through the system, and a “bake-out” system was used to clean all the ductwork involved, as well as a “bake-out” system in the oxidizer. This design insures total capture of particles and dramatically reduces costs for maintenance clean-up of the system.

In conclusion, this Coffee Roaster dramatically reduced:

• Operating costs 
• Maintenance costs 
• CO2 production.

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