However, the oxidation process produces fumes that cannot be allowed to pollute the atmosphere. Consequently, the incinerator burns the fumes so they do not affect air quality. Approximately 5 million BTU of heat is recovered from incinerating fumes and is used for secondary heating for asphalt storage tanks and heating combustion air for the burner on the incinerator.
The incinerator system, from Heatec, Chattanooga, TN, has a combustion chamber, two heat exchangers and an exhaust blower. Fumes are burned in the combustion chamber, which is lined with 6" thick ceramic-fiber-block insulation to eliminate heat loss. One heat exchanger has serpentine coils heated by gases from the combustion chamber. The coils serve as a secondary source of heat for asphalt that circulates through them from asphalt tanks. The other heat exchanger heats intake air for the burner on the combustion chamber.
The exhaust blower induces a draft in the combustion chamber, pulling in asphalt fumes from the blow tanks into the chamber. The fan has a variable speed drive that maintains constant pressure in the combustion chamber despite variations in the blow tanks.
Hydrocarbons from fumes entering the combustion chamber incinerate at 1,500 degrees F (816 degrees C), leaving only carbon dioxide and steam. The clean gases go through the two heat exchangers and are exhausted into the atmosphere. The Heatec incinerator not only protects the atmosphere, but conserves energy for lower fuel costs.
Heatec's system can be used to eliminate fumes or negative emissions from many processes other than asphalt.