(52c) High Performance Air Assisted Flare Design to Handle Purge Flow Conditions

One of the biggest challenges in the gas flaring process in petrochemical plants is the purge flow conditions. During normal operating conditions, the flare system receives much lower waste gases flow than the maximum expected amount of waste gases during the sudden shutdown or upset in the whole system. Therefore, waste gases at purge flow conditions combust with poor efficiency because of the lack of the required mixing energy between the waste gases and the ambient air. In this study, our research group designed, built, and tested a new air assisted flare of an industrial size that is capable of overcoming this challenge by providing the required momentum and air to the waste gases flow, thus ensuring an efficient combustion process for waste gases and a better flare performance. The new design included a radial slot jet at the end of the flare stack from which inward radial air was injected to adjust the exit area available for the waste gases flow, and increasing the waste gases flow rate. The new air assisted flare design also provided a protection for the flare tip from the radiation heat; the flame heat could cause damage to the flare tip by cooling it the used air. Five different experiments from two groups were carried out to test the new designs under the low flow conditions. The first group included tests without using the new design while the second group included the same test conditions using the new design. The obtained new design results were compared to the tests without the new design. The results showed a significant improvement in the combustion efficiency and in the flare performance when the new design was employed.