TACCOS—A thermography-assisted combustion control system for waste incinerators

Abstract

A novel type of combustion control system is described for municipal waste incinerators using infrared thermography to obtain information about the temperature distribution in the furnace interior. A scanner camera operating in the mid infrared was installed at the waste-to-energy plant in Coburg, Germany during the experiments. Selection of an appropriate wavelength region allows the direct imaging of the fuel bed through the overlying flame and flue gas atmosphere and the determination of temperature distributions within seconds. The fast response time of the thermography system compared to shielded thermocouples allows the detection of furnace temperature fluctuations on a short time scale of a few minutes. These data can be used for fine tuning of the total underfire air (UFA) flow. Local imbalances in fuel bed temperature are evaluated to redistribute UFA between individual grate zones. The influence of variations in calorific value on the position of the main zone of combustion can easily be measured, thus allowing the sensitive adaptation of UFA distribution to local requirements. Incorporation of the camera system results in an improved overall consistency of the combustion process, as reflected by a reduction of excess air fluctuations and of temperature imbalances across the grate. Measurements in the Coburg plant have shown that flue gas as well as residue burnout quality was improved. Compared with conventional control, emissions of carbon monoxide and unburned hydrocarbons were reduced, and also the fraction of unburned matter in the residue.