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

Abstract

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.

Influence of lithium salts on the combustion characteristics of dimethyl carbonate-based electrolytes using a wick combustion method

“…The fiber-optic spectrometer was utilized to measure the light emission intensities of the flames given by the electrolytes. The measurable wavelength range of the spectrometer is 200~800 nm, which has been commonly applied in combustion research [34,35]. The combustion residues from burned wick were characterized utilizing scanning electron microscopy (SEM) and X-ray diffraction (XRD).…”

Investigation on Oxidation Behavior of Super304H and HR3C Steel in High Temperature Steam from a 1000 MW Ultra-Supercritical Coal-Fired Boiler

“…Furthermore, the existence of thermal coefficients of expansion discrepancy between the outer and inner layer cannot be ignored under the real condition, providing the motivation for the crevice formation. During the service of the material, the ambient temperature of the superheater and the reheater fluctuated within a certain range [26]. When the ambient temperature fluctuated periodically, the stress acting on the oxide scale also alternated between the tensile stress and the compressive stress.…”

Application of Sapphire-Fiber-Bragg-Grating-Based Multi-Point Temperature Sensor in Boilers at a Commercial Power Plant

“…Sensor and control technologies provide the foundation that will enable operators to fully utilize these technological advances for reliable system integration, addressing cybersecurity concerns, and optimizing plant operations. Techniques that utilize optical pyrometers, precious metal thermocouples, and acoustic pyrometers are used primarily for detection and prevention of catastrophic events and are typically deployed for single-point measurement [1,2,3,4]. Furthermore, these devices are limited by temperature and can be cost prohibitive or invasive if deployed in large numbers to obtain distributed temperature measurements [1,2,3,4].…”

“…Techniques that utilize optical pyrometers, precious metal thermocouples, and acoustic pyrometers are used primarily for detection and prevention of catastrophic events and are typically deployed for single-point measurement [1,2,3,4]. Furthermore, these devices are limited by temperature and can be cost prohibitive or invasive if deployed in large numbers to obtain distributed temperature measurements [1,2,3,4]. Mature fiber optic sensing technologies are attractive options for these applications, due to their (partly) insusceptibility to electromagnetic interference (EMI).…”