Real-Time Measurement of Industrial Gas Flare Emissions via UAS Technology

Paper from the AFRC 2018 conference titled Real-Time Measurement of Industrial Gas Flare Emissions via UAS TechnologyIndustrial Gas flares are used world-wide to reduce safety concerns in up-steam and down-stream production of hydrocarbon products. These flares are generally classified as non-assisted utility flares, steam-assisted flares, air-assisted flares, pressure-assisted flares, enclosed flares, liquid flares and pit flares. These flares are designed to operate for very low hydrocarbon flow rates (due to fuel cost) and high hydrocarbon flow rates (due to safety constraints). They must also perform under variable ambient conditions (e.g., wind and rain) for non-uniform gas compositions. Hydrocarbon plants are often required to have a "Flare Minimization Plan" as part of their air permit. Plants that "routinely" flare gas also include flare gas recovery units to improve plant efficiency and reduce environmental impact. Flare stacks are designed to burn flammable gases high enough to minimize radiation flux to surrounding equipment and work areas and to reduce ground level concentrations of combustion emissions. Current technology used to monitor flare performance measure radiation levels, flare gas flow rates and compositions and ground level concentrations for CO, NOx, VOC's. Early work aimed at characterizing flare efficiency was limited to small single point elevated flares using extractive sampling techniques. More recent studies extended this by using techniques such as Differential Absorption LIDAR (DIAL), Open-Path Fourier Transform Infra-Red Spectroscopy (OPFTIR), passive FTIR (PFTIR) and Video Imaging Spectro-Radiometry (VISR). Data collected using these techniques were subject to temporally and spatially varying flare plumes from a single source. Results reported from this work typically are averaged which fails to capture the dynamic nature of flare operation under various ambient conditions. Also, none of these techniques have been applied to Multi-Point Ground Flares (MPGF) due to the size of the flare field and the associated sampling limitations.; Elevated Analytics, Inc. has developed advanced sensor systems using various fast acting sensors to measure local gas concentrations, temperature and relative humidity of flare plumes. This data is reported from the UAS device(s) wirelessly to the ground monitoring station that can then be linked directly to the plant digital control system to effectively control flare operations as a function of plant operations. These sensor systems have been applied in various applications which will be discussed in this paper. Real-time spatially and temporally accurate data has been used to develop "time-varying" contour plots of local air quality and temperature. This feature allows the system to function as an early warning device as well and allows the plant to function at higher capacities without risking inefficient flare operation