Thermal Oxidizing Flare Vapor Combustion Equipment
Vapor Destruction Equipment Description
Thermal Oxidizing Flares are generally provided in two basic configurations; open flame and enclosed flame systems. The operation of both systems is very similar and therefore they have many similar or identical components. As the name implies, the Thermal Oxidizing Flare is a modification of a traditional elevated flare commonly seen in refineries and chemical plants, but with additional safety and operational features that make it suitable for terminal applications.
The open flame Thermal Oxidizing Flare has an elevated, non-enclosed vapor burner mounted at the top of a vertical riser. The height of the riser is dependent on the loading rate, vapor composition and radiation of the flame. Typically, an open flame system has an overall height of 50 feet (15 meters) or less.
The Enclosed Thermal Oxidizer (Flare) has the vapor burner mounted near grade, but surrounded by an insulated shell. If sized adequately, the shell is large enough to totally contain the flame. The flame should not be directly visible. For higher destruction efficiencies, additional fuel gas can be added and/or the combustion air can also be controlled to an enclosed system.
The major components of the open and enclosed systems vapor combustion (destruction) systems generally include:
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Burner element designed to protect against vapor burnback
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Automatic pilots
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Continuous pilot monitoring
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Automatic vapor staging valves
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Flame or detonation arrestors
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Assist air blower to promote smokeless combustion
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Hydraulic seal vessel
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Detonation flame arrester
After a typical combustion system start-up sequence of an air purge, ignition trials and pilot confirmation, hydrocarbon vapor can be introduced in the Thermal Oxidizing Flare.
The hydrocarbon and air mixture flow through several devices designed and controlled to prevent burnback from occurring in the vapor header. Since it is possible and even likely that the hydrocarbon/air mixture coming from the loading operation is in the explosive range, it is critical that safety devices be in place to prevent the flame at the burner tip from propagating back through the vapor header. Although the devices and their flow sequence can vary from manufacturer to manufacturer, a hydraulic seal in combination with a flame arrestor or detonation arrestor alone are common. In addition, staging valves are used to maintain the velocity of the waste gas at the burner tip. As the vapor flow increases or decreases, more burner stages are open or closed to accommodate the flow changes. A special burner design is generally used to prevent burnback.
Without additional energy added to the combustion process, some hydrocarbon vapors can smoke during combustion in this type of process. The assist air blower adds more mixing energy during combustion to enhance smokeless combustion