Monitoring oxy-coal flame stability
- Authors: Valliappan, Palaniappan , Wilcox, Steven , Spliethoff, Hartmut , Diego Garcia, Ruth
- Date: 2018
- Type: Text , Conference proceedings
- Relation: 27th IEEE International Symposium on Industrial Electronics, ISIE 2018; Cairns, Australia; 13th-15th June 2018 Vol. 2018-June, p. 847-853
- Full Text: false
- Reviewed:
- Description: This paper presents a novel approach to monitoring the stability of oxy-coal flames. Oxy-coal combustion has the potential to generate high concentrations of carbon dioxide in the exhaust gas stream. This could increase the efficiency of the removal of carbon dioxide emissions from a coal fired utility boiler. In order to convert an existing boiler high levels of flue gas need to be recycled to reduce the combustion zone temperatures, but this can lead to combustion instability. This paper presents an approach using three broadband photodiodes to monitor the infra-red, visible and ultra-violet emissions from an individual flame and then, by using the Wigner-Ville transform, detect unstable flames.
- Description: IEEE International Symposium on Industrial Electronics
Detecting burner instabilities using joint-time frequency methods whilst co-firing coal and biomass
- Authors: Valliappan, Palaniappan , Thai, Shee Meng , Wilcox, Steven , Ward, John , Tan, Chee Keong , Jagietto, Krzysztof
- Date: 2011
- Type: Text , Conference paper
- Relation: ASME/JSME 2011 8th Thermal Engineering Joint Conference, AJTEC 2011
- Full Text: false
- Reviewed:
- Description: Conventional coal-fired burners are designed to operate within specific limits that, in part, result from the need to efficiently burn the fuel. These designs have been developed to ensure stable combustion, lower NOx emissions and increase the combustion efficiency through techniques such as air staging and adding swirl to the combustion air. Recent requirements to reduce CO 2 emissions from coal-fired boiler plant has focussed on the co-firing of biomass, primarily wood, either by delivering the pulverised biomass with the coal or through separate burners. To date this approach has typically taken place at substitution levels of around 5% by mass and at these levels the operation of the burners and boiler is not adversely affected. However, as the proportion of biomass increases the fuel characteristics of the blend moves further away from the burner design parameters. This can lead to combustion instabilities and in extreme cases extinction of the flame. In order to co-fire higher concentrations of biomass a system or technique is required that can detect the onset of these instabilities and warn before the combustion conditions become dangerous. In this paper a novel technique based around the Wigner-Ville transform is presented that shows promise at being able to temporarily resolve the conditions that could result in the onset of burner instabilities for three cases; the first will present results from the combustion of 100% bituminous coal, whilst the second and third cases will present the results from experiments where the proportion of biomass was set at 10% and 20% by mass with the same bituminous coal. In each experiment the secondary combustion air was first reduced from a nominal stable condition and then subsequently increased from the same stable condition. It was found that the Wigner transform was able to resolve flicker frequency changes as the airflow rate was reduced. These changes were subsequently used in a neural network to automatically detect drastic changes in the air flow rates to the burner and could provide a means by which utility operators could detect dangerous flame instability conditions in real-time. Copyright © 2011 by ASME.
Development of a flame monitoring and control system for oxy-coal flames
- Authors: Valliappan, Palaniappan , Wilcox, Steven
- Date: 2017
- Type: Text , Conference proceedings , Conference paper
- Relation: 2017 IEEE International Conference on Mechatronics, ICM 2017; Gippsland, Australia; 13th-15th February 2017 p. 482-486
- Full Text: false
- Reviewed:
- Description: This paper presents a novel approach to the monitoring and control of oxycoal flames when using high levels of recycled flue gas. Oxycoal combustion is one approach to mitigate the emissions of carbon dioxide from coal fired utility boilers but particularly when retrofitting the technology, the recycle of high levels of flue gas can lead to combustion instability. This paper investigates an approach using three broad band photodiodes to monitor the infra-red, visible and ultra-violet emissions from an individual flame and then by a combustion of signal progressing using the Wigner-Ville transform and artificial neural networks to monitor, diagnose and then suggest control actions to maintain a stable flame that has been demonstrated at pilot scale. © 2017 IEEE.
- Description: Proceedings - 2017 IEEE International Conference on Mechatronics, ICM 2017
The monitoring and control of burners co-firing coal and biomass
- Authors: Valliappan, Palaniappan , Jagietto, Krzysztof , Wilcox, Steven
- Date: 2012
- Type: Text , Conference paper
- Relation: ASME 2012 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference p. 139-149
- Full Text: false
- Reviewed:
- Description: The monitoring and control of combustion systems co-firing coal and biomass is a critical consideration when aiming to increase the proportion of biomass being combusted. This is because it is likely that the combustion will become increasingly unstable as the biomass proportion increases. In order to develop a flame monitoring and control system, flame signal data sets were collected from combustion measurements taken on a 500kW pilot scale combustion test facility. The sensors used were photodiodes with sensitivities in the UV, visible and IR wavelengths. The analysis of these data, identified flame features that can be related to operational parameters such as flame stability, excess air level, NOx and CO emissions. These features were then applied in the development of an intelligent flame monitoring and optimisation system for individual burners based on these low cost sensors. The testing of the monitoring and control system on a pilot scale burner and at full scale are described in this paper.