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Recent Advances in the Cubatão Scanning Lidar to Monitor Industrial Flares

Recent Advances in the Cubatão Scanning Lidar to Monitor Industrial Flares. J. L. Guerrero-Rascado 1,2,3 , R. F. da Costa 3 , A. E. Bedoya 4 , R. Guardani 5 , L. Alados-Arboledas 1,2 , A. E. Bastidas 4 and E. Landulfo 3

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Recent Advances in the Cubatão Scanning Lidar to Monitor Industrial Flares

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  1. Recent Advances in the Cubatão Scanning Lidar to Monitor Industrial Flares J. L. Guerrero-Rascado1,2,3, R. F. da Costa3, A. E. Bedoya4, R. Guardani5, L. Alados-Arboledas1,2, A. E. Bastidas4and E. Landulfo3 1Instituto Interuniversitario de Investigación del Sistema Tierra en Andalucía (IISTA-CEAMA), Granada, España 2Dpto. FísicaAplicada, Universidad de Granada, Granada, España 3Centro de Lasers e Aplicações, Instituto de PesquisasEnergéticas e Nucleares (IPEN), São Paulo, Brasil 4Escuela de Física, Universidad Nacional de Colombia, Medellín, Colombia 5Dpto. EngenheriaQuímica, Universidade de São Paulo, São Paulo, Brasil rascado@ugr.es

  2. MOTIVATION • The emission of pollutants in megacities and industrial areas can have strong impact: environment and human health Dust loading maps ( g/m2) calculated by DREAM model • Serious health effects: premature death, heart attacks, acute bronchitis and aggravated asthma among children • Premature mortality can be associated to the presence of particulate matter [Molina and Molina, J. Air Waste Manag. Assoc. 2004] VIII WLMLA, Cayo Coco 9thApril

  3. MOTIVATION • Cubatão is an industrialized city, the most polluted city in the world (United Nations) in the 80s • A large pollutant monitoring program started • In 1983, however, CETESB carried out a pollution control program to reduce air, water, and soil pollution • Sluggish dispersion of air pollutants  extreme discomfort and long term health problems for the population (particularly blood-related and respiratory diseases, and birth defects) Dust loading maps ( g/m2) calculated by DREAM model VIII WLMLA, Cayo Coco 9thApril

  4. MOTIVATION • One of the sources of pollutants in the city comes from biomass burning and oil refineries Dust loading maps ( g/m2) calculated by DREAM model • Lidar: very useful due to very high spatial (~m) and temporal resolution (~s) • Its performance in the near range must be tested to get trustable information from flames OBJECTIVES: 1-. characterization of the electronic subsystem 2-. development of methodology to characterize optical and microphysical properties inside industrial flares VIII WLMLA, Cayo Coco 9thApril

  5. EXPERIMENTAL SITE ~ 400 m • CEPEMA (Centre for Training and Research in Environment) • Cubatão (23º 53' S, 46º 26' W, 10 m asl), state of São Paulo (Brazil) • surrounded by mountains to N, W, and E (600-1000 m), and by the sea to S • 40 km2 with: 23 large industry complexes, 1 steel plant, 1 oil refinery, 7 fertilizer plants, 1 cement plant, and 11 chemical/petrochemical plants •  in total 260 pollutant emission sources VIII WLMLA, Cayo Coco 9thApril

  6. INSTRUMENTATION 3-λ SCANNING LIDAR • Nd:YAG laser (CFR 450, Quantel SA) • Emission/detection: 355, 532, 1064 nm • Repetition rate: 20 Hz • Analog (AN) and Photon Counting (PC) detection • Newtonian telescope • Scanning system: 2 AP sun • tracker (Kipp & Zonnen) • selectable spatial resolutions: • 3.75, 7.5, 15 and 30 m VIII WLMLA, Cayo Coco 9thApril

  7. METHODOLOGY Qualityassurancetests Different tests routinely applied in LALINET and EARLINET networks to detect potential anomalies in the electronic subsystem of the Cubatão scanning lidar • Zero-bin calibration: Trigger in a lidar is used to fire pulses and also to activate the data acquisition Lidar (light detection and ranging) … but ranging based on timing scatterers Ideally laser and chronometer are synchronized In practise… not wrong range determination!!! chronometer laser VIII WLMLA, Cayo Coco 9thApril

  8. METHODOLOGY Qualityassurancetests How to measure zero-bin calibration? Zero-bin test: a target is placed at the output of the laser window in order to produce strong backscattered radiation. Thus, the first intense peak observed by the detector system should correspond to the zero position of our measurements Our target is placed at zero-bin, however… Laser beam output telescope lidar VIII WLMLA, Cayo Coco 9thApril

  9. METHODOLOGY Qualityassurancetests • Bin-shift calibration: PC signals saturated in near-range  zero-bin calibration does not allow for unambiguously determining the zero-bin position for these channels Comparison of the shape of AN and PC signals: both signals should simultaneously detect atmospheric targets at the same distance for ideal systems VIII WLMLA, Cayo Coco 9thApril

  10. METHODOLOGY Qualityassurancetests How to measure bin-shift calibration? Bin-shift test: Bin-shift is determined by the best linear fit in a certain distance range between AN and PC signals (using AN signal as a reference), sliding the PC signal around it 10-min measurement, sliding window between −20 and + 20 bins VIII WLMLA, Cayo Coco 9thApril

  11. METHODOLOGY Qualityassurancetests • Dark current: Response exhibited by a receptor of radiation during periods when it is not actively illuminated. • measurement taken by covering totally the telescope or detectors performed with enough averaging time (~10 min) • all parameters (voltages, pulse repetition frequency …) are configured as a usual measurement Laser beam output telescope lidar VIII WLMLA, Cayo Coco 9thApril

  12. METHODOLOGY RETRIEVAL OF OPTICAL PROPERTIES 12x12 virtual matrix used to discretize the flare region in steps of 0.02º (zenith) and 0.03º (azimuth), integration time 10 s VIII WLMLA, Cayo Coco 9thApril

  13. METHODOLOGY RETRIEVAL OF OPTICAL PROPERTIES Lidar signal at a given distance: Forming the ratio at the leading and trailing edge of the flame : Some considerations: Flare stack is at 400 m from the instrument  O(r)=1 Atmosphere is horizontally homogeneous around the flame  β(r1)=β(r2) VIII WLMLA, Cayo Coco 9thApril

  14. METHODOLOGY RETRIEVAL OF OPTICAL PROPERTIES Particle extinction coefficient, assuming homogeneity between r1 and r2 : Finally, the extinction-related Angströmexponent: VIII WLMLA, Cayo Coco 9thApril

  15. RESULTS RESULTS ON ZERO-BIN CALIBRATION • Different spatial resolutions (i.e., at 3.75, 7.5, 15 and 30 m) in order to check the instrumental characterization at each setting • Zero-bin position is located at bins #10 and #11 (depending on wavelength) • Zero-bin position is different for different spatial resolutions selected • Lidar technique is a timing technique (which in turn is converted into a ranging technique through the light velocity)  the temporal delay between the laser beam emission and start of data acquisition is converted to a different number of bins when different spatial resolutions are used VIII WLMLA, Cayo Coco 9thApril

  16. RESULTS RESULTS ON QUALITY TESTS • Relationship among zero-bin positions at different spatial resolutions: n = 0,1,2,3 determine the different spatial resolutions (resolution(n) = 3.75·2n) VIII WLMLA, Cayo Coco 9thApril

  17. RESULTS RESULTS ON BIN-SHIFT test • Orographic conditions led to low clouds formation (typically <1 km) • Bin-shift calibration requires a distance-range where both AN and PC properly detect atmospheric structures (aerosol layers or clouds) simultaneously  operation at a zenith angle of 25° to guarantee profiling a target at 1.5-2.5 km from the system VIII WLMLA, Cayo Coco 9thApril

  18. RESULTS RESULTS ON BIN-SHIFT test • All bin-shifts were found to be negative, meaning all PC signals are displaced several bins towards the instrument (with respect to the AN signals) • Bin-shift test not applicable to 1064 nm due to extremely low SNR • . • #0 bins for most of them  synchronization between emission and start of data acquisition VIII WLMLA, Cayo Coco 9thApril

  19. RESULTS RESULTS ON DARK CURRENT • AN dark current was constant with positive values for the entire distance range sounded, except very close to the instrument where stray-light peaks are detected up to 250 m from the instrument • PC dark current showed an expected value of zero in most of the distance range VIII WLMLA, Cayo Coco 9thApril

  20. RESULTS RESULTS ON MAPPING FLAMES • Values at each virtual pixel were computed as the mean value of 5 bins along the lidar line-of-sight (range 367.5-397.5 m  bins 49-53) • better identification of flame boundaries at larger wavelengths VIII WLMLA, Cayo Coco 9thApril

  21. RESULTS RESULTS ON MAPPING FLAMES • Optical properties: • α355,532largest values at the center of the flame base • α1064is maximum in a ring around the center of the flame base • Larger AE in the bottom of the flame (hot region) than in the top (cold region) nucleation and subsequent coagulation increases as distance from the emission point * Hot region (<3 pixels surrounding the emitter point) * Cold region (>4 pixels respect to the emitter point) VIII WLMLA, Cayo Coco 9thApril

  22. RESULTS RESULTS ON MAPPING FLAMES • Since 1993 several studies point out the relevance of the spectral variation of the Angströmexponent (i.e. its curvature) to obtain information of the corresponding particle size distribution • [Gobbi et al, ACP, 2007] & [Perroneet al. ACP, 2014]: graphical method based on spectral variation of AE (i.e. its curvature) is related to particle size distribution (Rfine & η) Hot region particles: mainly 0.15< Rfine <0.25 µm & 50%< η <100% Cold region particles:mainly 30%< η <70% less concentration of fine particles as a consequence of the coarse mode particles generation by coagulation Rfineslightly decreasing in cold region  higher efficiency of the fine particles with larger sizes to coagulate VIII WLMLA, Cayo Coco 9thApril

  23. CONCLUSIONS • The results indicates that to properly use the lidar signals in any lidarprocedure (i.e. derivation of range corrected signals plots, Klett-Fernald method and Raman algorithm, among others) some corrections must be applied such as some bins of the AN and PC signals must be removed and dark current must be subtracted. • The case study allowed to illustrate the procedure to retrieve optical and microphysical properties (Gobbi modified graphical method) of particles in flames. This work demonstrates the capabilities of the multiwavelength elastic scanning lidaras a promising tool for industrial flare research. VIII WLMLA, Cayo Coco 9thApril

  24. … thankyouverymuch More details in: J.L. Guerrero-Rascado, R. da Costa, A. E. Bedoya, R. Guardani, L. Alados-Arboledas, A. E. Bastidas, and E. Landulfo, Multispectral elastic scanning lidar for industrial flare research: characterizing the electronic subsystem and application, OPTICS EXPRESS, 31063, Vol. 22, No. 25, DOI:10.1364/OE.22.031063 (2014) VIII WLMLA, Cayo Coco 9thApril

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