ENV-16-22 Performance Evaluations of Variable Speed Air-Assisted Flares Using Passive FTIR

Description:

Tesoro Alaska Company LLC contracted with IMACC, LLC to conduct a combustion efficiency performance test on the existing air-assisted flare at its Kenai Alaska Refinery. The test was in accordance with an approved EPA test plan. The main objective of this test was to prepare a combustion efficiency performance curve for the flare over a range of flare operating conditions. While the flare operating conditions were purposefully varied between test runs, each individual test run was conducted under stable conditions. The performance test utilized Passive Fourier Transform Infrared spectroscopy (PFTIR) technology and measured the air-assist rate provided by the current fan and variable speed drive motor, and assessed the combustion efficiency of the flare under varying vent gas flow rates of differing calorific values and different assist-air flow rates. During each test condition, the PFTIR remotely analyzed the resulting combustion gases in the flare plume to determine combustion efficiency. Data from the performance test are used to: - Provide a detailed description of the extent to which the ratio of mass flow rate of air to the stoichiometric mass air flow for the vent gas (ṁair-asst/ṁair-stoich-vg) affects combustion efficiency; - Provide a detailed description of the range of the ṁair-asst /ṁair-stoich-vg that the Kenai Air-Assisted Flare can operate within to ensure a minimum 96.5% Combustion Efficiency (or as high an efficiency as reliably obtainable), taking into consideration variability in Vent Gas flow rate and composition; and -Describe the maximum ṁair-asst /ṁair-stoich-vg at which Tesoro proposes to operate the Kenai Air-Assisted Flare. Following the completion of the test, supplemental data analysis was conducted to evaluate future performance of the flare in conformance with the new MACT Subpart CC dilution air parameter.