Optical sensing for MILD Combustion monitoring

Sustainable thermochemical conversion processes require new monitoring and control strategies relying on proper diagnostics methodologies capable of reconstructing the reactive state as a function of the operational conditions with a reasonable low cost. This requirement pushes for the re-thinking of combustion diagnostics strategies. In addition, sustainable combustion generally relies on advanced processes, as MILD Combustion, which is characterised by reactive structures very different from those of standard combustion at macro and micro scale. The most relevant features are the absence of a visible flame and the onset of a distributed com-bustion regime with a substantial absence of propagative/deflagrative phenomena. These changes are key for improving the performances and reducing pollutants emission, but they also affect the standard approach of combustion sensing techniques. For this reason, and to account for the new concept of distributed sensing, it would be important to set up innovative diagnostics realized by means of a large number of sensors, strategically distributed within the combustion chamber. The effective implementation of such approaches requires simple sensing units, but also the availability of a numerical description of the reactive processes, with a clear and univocal connection of the measured quantities to specific progress indicators and process outcomes.In this paper a simple application of CH* and OH* chemiluminescence measurements collected in a MILD Combustion burner is presented. Results are correlated to the process stability, along with data of gas species concentrations carried out in the same positions of the luminous emission measurements and in the exhausts. On the ground of the evidence here presented, the specifications of an integrated probe to be used for the set-up of a monitored control of a real device can be derived.

Automated summary

Sustainable thermochemical conversion processes require new monitoring and control strategies based on suitable diagnostics methodologies. This involves rethinking combustion diagnostics strategies and utilizing a large number of strategically distributed sensors in the combustion chamber for innovative diagnostics.