Experiments on Measurement of Temperature and Emissivity of Municipal Solid Waste (MSW) Combustion by Spectral Analysis and Image Processing in Visible Spectrum

Yan, Weijie; Zhou, Huaichun; Jiang, Zhiwei; Lou, Chun; Zhang, Xiaoke; Chen, Donglin

doi:10.1021/ef401374y

Cited by 56 publications

(28 citation statements)

References 27 publications

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“…To quantitatively analyze the spectra of the flame's spontaneous emission, it is necessary to calibrate the profile of the spectral radiation intensities I(λ) along the wavelength. As described in [14,15,17], a blackbody furnace was used to obtain the calibration coefficients k(λ) = I b (λ)/S b (λ). Figure 2 shows the profiles of k(λ) within the wavelength range from 500 nm to 900 nm at four temperatures: 1273, 1373, 1473, and 1573 K. It can be seen that profiles of the calibration coefficients at different blackbody temperatures were consistent with each other; thus, it can be concluded that the calibration coefficients remained independent of temperature.…”

Section: Measurement Principlementioning

confidence: 99%

“…The spontaneous emission spectra of flames contain continuous spectra from the blackbody radiation of solid particles (e.g., soot, char, or ash particles); from the band spectra produced by the radiation of gas molecules (e.g., CO 2 or H 2 O); from the chemiluminescence of excited radicals (e.g., OH, CH, or C 2 ); and from the line spectra of free atoms (e.g., alkalis or alkaline earth metals) [10]. Based on the measurement and analysis of the spontaneous emission spectra of flames, FES has been proposed to determine equivalence ratios [9], to monitor flame stoichiometry [9,11] and to calculate flame temperatures in a natural gas-fired furnace [12], a pulverized coal-fired furnace [13,14], a gasification facility [15], an aluminum flame [16], and even an MSW incinerator [17]. For the flame of the MSW incinerator, strong characteristic emission lines of Na and K are observed in the visible spectra in the experiments, and more studies are needed to know if this type spectrum could be used for measurement temperature, while related works are relatively few in number.…”

Section: Introductionmentioning

confidence: 99%

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In Situ Measurement of Alkali Metals in an MSW Incinerator Using a Spontaneous Emission Spectrum

et al. 2017

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This paper presents experimental investigations of the in situ diagnosis of the alkali metals in the municipal solid waste (MSW) flame of an industrial grade incinerator using flame emission spectroscopy. The spectral radiation intensities of the MSW flame were obtained using a spectrometer. A linear polynomial fitting method is proposed to uncouple the continuous spectrum and the characteristic line. Based on spectra processing and a non-gray emissivity model, the flame temperature, emissivity, and intensities of the emission of alkali metals were calculated by means of measuring the spectral radiation intensities of the MSW flame. Experimental results indicate that the MSW flame contains alkali metals, including Na, K, and even Rb, and it demonstrates non-gray characteristics in a wavelength range from 500 nm to 900 nm. Peak intensities of the emission of the alkali metals were found to increase when the primary air was high, and the measured temperature varied in the same way as the primary air. The temperature and peak intensities of the lines of emission of the alkali metals may be used to adjust the primary airflow and to manage the feeding of the MSW to control the alkali metals in the MSW flame. It was found that the peak intensity of the K emission line had a linear relationship with the peak intensity of the Na emission line; this correlation may be attributed to their similar physicochemical characteristics in the MSW. The variation trend of the emissivity of the MSW flame and the oxygen content in the flue gas were almost opposite because the increased oxygen content suppressed soot formation and decreased soot emissivity. These results prove that the flame emission spectroscopy technique is feasible for monitoring combustion in the MSW incinerator in situ.

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Section: Measurement Principlementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

In Situ Measurement of Alkali Metals in an MSW Incinerator Using a Spontaneous Emission Spectrum

et al. 2017

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“…To further characterize the cameras, calibration was required. In a previous study on image processing techniques, the R, G, and B data of a pixel in the color digital camera are not proportional to the monochromatic radiative intensities because of the broad spectral response spectra of the R, G, and B bands of the color camera [16][17][18][19]. To characterize the relative spectral response of the camera, an experiment similar to Ref.…”

Section: Calibrations Of the Digital Color Cameramentioning

confidence: 99%

“…Kotzagianni et al [11] applied laser-induced breakdown spectroscopy (LIBS) for uniform methane-air mixtures spanning a wide range of compositions and for turbulent non-premixed and premixed flames. Flame image processing techniques based on a digital camera used for pyrometric measurements have been used to measure flame temperature and radiative properties [12][13][14][15][16][17][18][19][20][21]. In a previous study [18], a color digital camera was used to capture the flame image in visible spectrum.…”

Section: Introductionmentioning

confidence: 99%

Measurement of Soot Volume Fraction and Temperature for Oxygen-Enriched Ethylene Combustion Based on Flame Image Processing

et al. 2017

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Abstract:A method for simultaneously visualizing the two-dimensional distributions of temperature and soot volume fraction in an ethylene flame was presented. A single-color charge-coupled device (CCD) camera was used to capture the flame image in the visible spectrum considering the broad-response spectrum of the R and G bands of the camera. The directional emissive power of the R and G bands were calibrated and used for measurement. Slightly increased temperatures and reduced soot concentration were predicted in the central flame without self-absorption effects considered, an iterative algorithm was used for eliminating the effect of self-absorption. Nine different cases were presented in the experiment to demonstrate the effects of fuel mass flow rate and oxygen concentration on temperature and soot concentration in three different atmospheres. For ethylene combustion in pure-air atmosphere, as the fuel mass flow rate increased, the maximum temperature slightly decreased, and the maximum soot volume fraction slightly increased. For oxygen fractions of 30%, 40%, and 50% combustion in O 2 /N 2 oxygen-enhanced atmospheres, the maximum flame temperatures were 2276, 2451, and 2678 K, whereas combustion in O 2 /CO 2 atmospheres were 1916, 2322, and 2535 K. The maximum soot volume fractions were 4.5, 7.0, and 9.5 ppm in oxygen-enriched O 2 /N 2 atmosphere and 13.6, 15.3, and 14.8 ppm in oxygen-enriched O 2 /CO 2 atmosphere. Compared with the O 2 /CO 2 atmosphere, combustion in the oxygen-enriched O 2 /N 2 atmosphere produced higher flame temperature and larger soot volume fraction. Preliminary results indicated that this technique is reliable and can be used for combustion diagnosis.

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“…However, expensive equipment and complex optical systems are required; therefore, this approach is not easily applied to industrial furnaces. Image processing techniques, based on a tri-chromatic signal of the image and using the two-color method, have been widely used for temperature measurements of furnace flames [7][8][9][10]. The emission from emitters at two wavelengths is utilized to calculate the temperature and emissivity in image processing techniques.…”

Section: Introductionmentioning

confidence: 99%

Spectrometer-Based Line-of-Sight Temperature Measurements during Alkali-Pulverized Coal Combustion in a Power Station Boiler

Yan

et al. 2017

Energies

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Abstract:A portable spectrometer system that simultaneously measures the temperature, emissivity, and radiation intensity of an alkali metal was used in a 1000 MW coal-fired power plant boiler furnace. A calibrated fiber-optic spectrometer system was applied to obtain the radiation intensity of the flame. A simple method based on polynomial fitting was used to separate the continuous baseline from the measured flame spectra that contained both continuous and discontinuous bands. Nine synthetic spectra that included the baseline, noise, and three simulated discontinuous bands based on a Gaussian function were created to test the accuracy of the separation method. The accuracy of the estimated continuous baseline was evaluated by the goodness-of-fit coefficient quality metric. The results indicated good spectral matching for the selected profiles. The soot emissivity model by Hottel and Broughton was employed to calculate temperature and emissivity. The influence of discontinuous emission spectra on the temperature and emissivity calculations was evaluated. The results showed that the maximum difference of the measurement points of the calculated temperature was only 6 K and that the relative difference in emissivity among the measurement points was less than 5%. In addition, a comparison between the actual intensity of the alkali metal and the calculated temperature indicated that the change in the radiation intensity of the alkali metal followed the trend of the calculated temperature. This study serves as a preliminary investigation for measuring gas-phase alkali metal concentrations in a furnace.

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Experiments on Measurement of Temperature and Emissivity of Municipal Solid Waste (MSW) Combustion by Spectral Analysis and Image Processing in Visible Spectrum

Cited by 56 publications

References 27 publications

In Situ Measurement of Alkali Metals in an MSW Incinerator Using a Spontaneous Emission Spectrum

In Situ Measurement of Alkali Metals in an MSW Incinerator Using a Spontaneous Emission Spectrum

Measurement of Soot Volume Fraction and Temperature for Oxygen-Enriched Ethylene Combustion Based on Flame Image Processing

Spectrometer-Based Line-of-Sight Temperature Measurements during Alkali-Pulverized Coal Combustion in a Power Station Boiler

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