Soft-Sensor for the On-Line Estimation of the Flue Gas Mass Flow in Biomass Boilers with Additional Monitoring of the Heat Exchanger Fouling

The flue gas mass flow is one of the fundamental quantities of biomass combustion processes. Its knowledge is highly beneficial for monitoring purposes and especially for the control of biomass boilers. However, typically applied measurement principles and existing soft-sensing approaches act highly sensitively to fouling of the measurement equipment and, thus, are not suitable for a long-term application. This paper presents a fouling insensitive soft-sensor for the on-line estimation of the flue gas mass flow. Exemplary results from a medium-scale biomass grate boiler attest highly satisfying estimation accuracy even during changes of the operating point of the boiler. Moreover, the proposed soft-sensor is not only insensitive to fouling, but can also be applied for fouling monitoring purposes.