Enclosed combustion devices, such as thermal and catalytic incinerators, operate at 14 kPa to 35 kPa (2 psi to 5 psi).  Operating pressure is either maintained at the oil/water separator or provided through a blower at the enclosure vent outlet.  Maintaining the required pressure at the enclosure normally requires adding structural reinforcement and alternate safety devices designed for higher pressures to the vapor cover and separator tank.  Installing a blower is often the most economical means of supplying the high pressure required for combustion at the incinerator.

In thermal incineration, vapor passes through a preheater to increase vapor temperature and subsequently reduce the amount of supplemental fuel required for complete combustion at 650°C to 870°C (1200°F to 1600°F).  The preheater uses hot incinerator exhaust to transfer heat to the influent vapor stream. 

Similarly, catalytic incinerators pass vapor over a catalyst material such as platinum, copper chromates, copper oxide, chromium, magnesium or nickel.  Raising the catalyst temperature releases adsorbed gases on the metal’s surface, which increases the catalytic oxidation reaction rate.  This also allows complete combustion to occur between 315°C and 370°C (600°F and 700°F), and reduces the supplemental fuel requirement below that of thermal incineration.  The concentrations of oxygen, carbon dioxide and water vapor may considerably reduce the heat value of the VOC in vapor.  With catalytic incineration, lightens may suddenly surface in the exhausted vapor and cause an explosion.  This poses a serious safety hazard, as temperature monitoring equipment normally does not react fast enough to prevent destruction of the catalyst. 

Since incinerators are a constant source of ignition, a flame-arresting device must be installed in the vapor exhaust line between the vapor enclosure and incinerator, a certain distance from the flame source.  Condensate traps can also prevent moisture from accumulating in the vapor line leading to the incinerator.

Vapor Recovery Devices
Flare Devices
Ignition Sources
Vapor Space Purging