Application of 2D temperature measurement to a coal-fired furnace using CT-TDLAS

The measurement of temperature and species concentrations in combustion fields is very significant to develop the high-efficient combustion technologies for energy conservation and emission reduction. There are various measurement technologies including contact and non-contact measurement. Tunable diode laser absorption spectroscopy (TDLAS) technology is a proven non-contact method to detect the temperature and species concentrations by absorption measurement. To enable two-dimensional (2D) representation of temperature and species concentrations in combustion fields, the TDLAS technology is usually combined with computed tomography (CT). The latter is however considerably new in combustion research, especially in solid fuels reaction environment. In this paper, a 32-path, 2D CT-TDLAS system for temperature measurement in a pilot scale, coal-fired furnace was developed. The accuracy of CT algorithm to reconstruct 2D temperature distributions in different laser-paths arrangements was first analysed using SSD (sum of squared difference) and ZNCC (zero-mean normalized cross-correlation) by comparing to 2D temperature distribution of a full scale coal-fired furnace simulated using computational fluid dynamics (CFD). The accuracy was improved by 32-path reconstruction. The study was then progressed to investigate its accuracy for measurement in a simple CH4-air burner configuration with rounded and rectangular cells as well as sensitivity for flame shift detection whereby the reconstructed temperature distribution was compared to temperature measured using thermocouple. It is verified that this CT reconstruction was feasible for various measurement areas, even if the center of flame was shifted. Finally, a 32-path, 2D CT-TDLAS system with rectangular structure cell was developed and applied for a temperature measurement in a TNB Research’s pilot scale coal-fired furnace. 2D temperature distribution in coal-fired furnace was reconstructed accroding to the experimental results. It is demonstrated the potential of CT-TDLAS for online 2D temperature measurement for actual applications.

This is the Accepted Manuscript version of an article accepted for publication in Measurement Science and Technology. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at https://doi.org/10.1088/1361-6501/ab4f05.