This patent application has not been assigned to a company or institution.
The following quote was obtained by the news editors from the background information supplied by the inventors: "The present invention relates to a multi-spectral infrared imaging system that provides real-time measurement of flare combustion efficiency, which would enable operators to adjust flare operating conditions to achieve higher efficiency. The multi-spectral infrared imaging system includes a machine readable storage medium, which provides instructions that cause the multi-spectral infrared imaging system to perform operations to obtain a combustion efficiency of a flare.
"Flares are widely used in chemical process industries (e.g., petroleum refineries, chemical plants, etc.). Due to the intended function and nature of flare design and operations, determination of flare combustion efficiency (CE) and destruction and removal efficiency (DRE) is extremely challenging. There has been a protracted debate on how much air pollutants are emitted from flares. The fact is that no one has a good answer to this question and this level of uncertainty regarding flare emissions is problematic for both regulators and industry.
"The TCEQ-UT flare study was a major undertaking. The method used in this study could be referred to as 'grab and measure' or 'extractive sampling' method. However, it is not practical to use the same approach to measure or monitor flare operations on a regular basis. The TCEQ-UT study did include two supplemental remote sensing based measurement systems with an intention to evaluate their effectiveness for practical flare monitoring. The two systems were an infrared (IR) Hyper-Spectral Imager by
"The study results suggested that the flare CE determined by IMACC's PFTIR/AFTIR was generally consistent with the CE determined by analysis of pre- and post-combustion gas samples thru the 'grab and measure' method. The mean differences between the two methods were about 2% to 2.5%, and average standard deviations were 2.8% to 3.2%. The data availability was 99% to 100%. The performance of Telops's Hyper-Spectral Imager was less desirable. The mean differences were 19.9%, standard deviations were 57.8%, and data availability was 39%.
"Both the Telops's Hyper-Spectral Imager and the IMACC's FTIR are powerful instruments for many applications, particularly research projects. However, they have some significant shortcomings if they are to be used as industrial analyzers to determine flare CE. These shortcomings are identified below.
"Telops' Hyper-Cam can be considered a two-dimensional array of FTIR spectrometers that can be combined to form images (i.e., each pixel in the image is equivalent to a single FTIR spectrometer). It has a scan rate of approximately 1 second per scan (depending on spectral resolution and other parameter settings). The flare plume changes rapidly in shape and position, and the resulting path length of the pixels in the Hyper-Cam Imager may change dramatically within the same data cube. This variability introduces unknown and uncontrollable factors into the pixel intensity-concentration equation, rendering calculations and results unreliable.
"IMACC's FTIR is a path measurement instrument. The results only represent the region where the IR light path intersects the flare plume. Due to the heterogeneous and dynamic nature of a flare, using the measurement from a small path to represent the entire flare is a concern. The IMACC FTIR also has a relatively long scan time (seconds) and suffers the same problem as the Telops Hyper-Cam. Since the IMACC FTIR is a single-path measurement instrument, this variability can be minimized by pointing the instrument to the middle, thick portion of the flare plume where the relative change in path length is small. If the IMACC FTIR is aimed at the fringe of the flare plume, or if the flare diameter is small, the effect of this temporal mismatch due to flare plume dynamics is expected to be much more salient and problematic. Selection and alignment of the measurement path could significantly influence results. This makes it impractical for routine monitoring as the system would need some sort of targeting system to ensure it is consistently aimed at the correct position in the flare plume while the plume may be constantly shifting in wind.
"Both the Telops's Hyper-Cam and the IMACC FTIR are delicate research instruments and require expert-level personnel to operate. They require significant effort to set up and maintain, and significant effort is required for post-processing/analyzing data in order to derive flare CE results. They do not provide real-time or near real-time measurements, and are not suitable instruments to provide continuous real-time feedback to operational personnel. The total ownership cost is very high (this is particularly true for Telops' Hyper-Cam).
"Flare emissions can swing over a wide range depending on operating conditions (e.g., amount of steam used to assist the flare). The current problem is that there is no mechanism to measure flare efficiency and provide timely feedback to flare operators to adjust operating conditions for a higher efficiency."
In addition to the background information obtained for this patent application, VerticalNews journalists also obtained the inventors' summary information for this patent application: "The multi-spectral infrared imaging system described in this specification is aimed at providing real-time measurement of flare efficiency, which would enable operators to adjust flare operating conditions to achieve higher efficiency. Considering contributions of flare emissions in total volatile organic compound and hazardous air pollutant emission inventories, the potential environmental benefit could be tremendous. An effective flare efficiency measurement tool will enable better flare operations and mitigate extremely high flare emissions that may otherwise go undetected. The proposed multi-spectral infrared imaging system is expected to be effective for all types of flares under all kinds of operating conditions.
"The multi-spectral imaging system for measurement of combustion efficiency of a flare includes a micro-lens array including a plurality of micro-lenses, a bandpass filter array including a plurality of filters, a detector array including an imaging unit capturing images of the flare and an analysis apparatus coupled to the imaging unit. The imaging unit produces at least three intensities from the images of the flare. A first intensity of said at least three intensities represents an amount of a first material contained in the flare, a second intensity of said at least three intensities represents an amount of a second material contained in the flare, and a third intensity of said at least three intensities represents an amount of a third material contained in the flare. The first material includes fuel, such as unburned hydrocarbons, and the second material includes carbon dioxide (CO.sub.2). The analysis apparatus includes a machine readable storage medium, which provides instructions that cause the analysis apparatus to perform operations to obtain the combustion efficiency of the flare. The operations includes steps of acquiring said at least three intensities from the imaging unit, retrieving a first absorption coefficient, a second absorption coefficient, a third absorption coefficient, and a weighted average carbon number for hydrocarbons expected in the flare vent gases, which are stored in the machine readable storage medium, and producing the combustion efficiency of the flare from said at least three intensities, the first absorption coefficient, the second absorption coefficient, the third absorption coefficient, and the weighted average carbon number for hydrocarbons expected in the flare vent gases. The first absorption coefficient is an absorption coefficient of the first material, the second absorption coefficient is an absorption coefficient of the second material, and the third absorption coefficient is an absorption coefficient of the third material.
"The fuel may include hydrocarbon. The third material may include carbon monoxide (CO).
"In addition to the at least three intensities, a fourth intensity may be acquired and used as a reference intensity to correct background infrared intensity. The step of producing the combustion efficiency of the flare includes producing the combustion efficiency of the flare from the at least three intensities corrected using the fourth reference intensity, the first absorption coefficient, the second absorption coefficient, the third absorption coefficient, and the weighted average carbon number of the hydrocarbons.
"The imaging unit may include an objective lens, a detector array including a plurality of detectors, a micro-lens array disposed between the objective lens and the detector array, and a bandpass filter array disposed between the micro-lens array and the detector array or at the aperture stop of the objective lens. Each of the detectors includes a plurality of sub-detectors. The detector array detects intensities from the images of the flare. The micro-lens array includes a plurality of micro-lenses. The bandpass filter array includes a plurality of bandpass filters. Each of the bandpass filters includes a plurality of sub-filters. The sub-filters have different wavelength bandpass windows from each other. The images of the flare passing through one of the micro-lenses are transmitted to one of the bandpass filters and being detected by one of the detectors.
"The first intensity is an intensity of the images of the flare passing through a first one of the sub-filters, the second intensity is an intensity of the same images of the flare passing through a second one of the sub-filters, the third intensity is an intensity of the same images of the flare passing through a third one of the sub-filters, and the fourth intensity is an intensity of the same images of the flare passing through a fourth one of the sub-filters.
"The first one of the sub-filters may have a wavelength bandpass window of absorption of hydrocarbons.
"The second one of the sub-filters may have a wavelength bandpass window of absorption of carbon dioxide.
"The third one of the sub-filters may have a wavelength bandpass window of absorption of carbon monoxide
BRIEF DESCRIPTION OF THE DRAWINGS
"A more complete appreciation of the invention, and many of the attendant advantages thereof, will be readily apparent as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicate the same or similar components, wherein:
"FIG. 1 schematically illustrates a multi-spectral infrared imaging system detecting flare to measure combustion efficiency of the flare.
"FIG. 2 schematically illustrates an arrangement of optical elements in the multi-spectral infrared imaging system.
"FIG. 3 shows an example of an arrangement of a micro-lens array and a bandpass filter array.
"FIGS. 4A and 4B show examples of an arrangement of the micro-lenses of micro-lens array and the sub-filters of the bandpass filter array.
"FIG. 5 shows absorption bands for carbon dioxide (CO.sub.2), carbon monoxide (CO), hydrocarbon (HC) and water (H.sub.2O).
"FIG. 6 shows a flowchart illustrating steps for the measurement of combustion efficiency at the super pixel level.
"FIG. 7 shows results of the measurement of combustion efficiency of a flare.
"FIG. 8 shows a configuration of model simulations for the measurement of combustion efficiency.
"FIG. 9 shows the simulation results of the measurement of combustion efficiency."
URL and more information on this patent application, see: Zeng, Yousheng; Morris, Jon; Dombrowski, Mark. Multi-Spectral Infrared Imaging System for Flare Combustion Efficiency Monitoring. Filed
Keywords for this news article include: Patents, Chemistry, Hydrocarbons, Carbon Monoxide, Organic Chemicals, Inorganic Carbon Compounds.
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