Control of Volatile Organic Compounds Emissions from Manufacturing

control can be used. Any breakdown in the boiler can result in expensive
process downtime. Consequently, the risk of shutdown should be kept
small and only streams that do not threaten boiler performance should be
int roduced.
For the satisfactory use of boilers as a control device, there are
several prerequisites. General ly, the burner must be modifi ed, the
boiler must operate continuously and concurrently with the pollution
source, the contaminants must be completely combustible, and the products
of combustion must not corrode the materials used to construct the
boiler. Corrosive VOC compounds can be combusted in a boiler, but
special attention must be given to operate above the dew point of the
flue gases. If these gases are allowed to condense, severe corrosion
problems will occur. Further, the volumetric flowrate of low VOC concen-
tration emission streams must be taken into consideration because they
can reduce thermal efficiencies in the same way as excess combustion ai r
does. The pressure drop caused by additional products of combustion
should not exceed the draft provided by boiler auxiliaries. Boiler -
life, efficiency, and capacity can be affected by the presence of con-
taminants in the VOC emission streams. Halogens, for example, would be
devastating to the life of boiler tubes. Finally, a personnel safety
hazard may occur if coal-fired boilers that are not pulverized coal-
fired are used to destroy organic waste. Any interruption in the air
supply to these types of boilers would release into the boiler house
combustion vapors and any hazardous or toxic substances that may have
been injectedO3O Great care, therefore, must be exercised in selecting
this mode of pollution control.
The large majority of industrial boilers are of water tube design.
Water, circulated through the tubes, absorbs the heat of combustion.
Drums store the superheated water from which steam is directed to external
heat exchangers for use as process steam. Boilers typically operate at
combustion chamber temperatures above 1,650°C (3,000°F) with a residence
time of about 1 second.31
Both forced and natural draft burners, designed to thoroughly mix
the incoming fuel and combustion air, may be used. After ignition, the
mixture of hot reacting gases passes through the furnace section that is
sized to allow the oxidation reaction to reach completion and to minimize