Microwave spectra inside the combustion chamber of a kraft recovery boiler – effects on communications.

Microwave‐based measurement can provide new methods and practical solutions for the challenging task of measurement inside large industrial combustion chambers. In order to measure or communicate inside a combustion chamber using microwaves, the spectrum of background noise at microwave frequencies must be known. This study investigates the basic electromagnetic spectrum in flames, concentrating on microwave frequencies from 0.1 to 19 GHz. The study introduces, as reference values, known results from forest flames and flames in controlled environments. The focus of the work is the level of background noise at microwave frequencies and the impact of this noise on radio communication inside the combustion chamber. The effects of the microwave radiation levels are compared with the requirements of practical communication systems such as Bluetooth and narrowband ISM (industrial, scientific, medical) systems at 800–950 MHz. [ABSTRACT FROM AUTHOR]