Combustion Flame Safeguarding

Paper from the AFRC 2017 conference titled Combustion Flame SafeguardingThe demand from both the industry and customers for optimal flame detection and dependable flame discrimination on Fired Process Heaters led Zeeco to develop a flame scanner that represents significant improvement over current flame rod and Ultra-Violet (UV) sensor technology. ; Both steam injection and the water vapor generated as a by-product of combusting high hydrogen-bound fuels can "blind" many UV scanners. A blinded scanner will trip the main burner, leading to temperature swings in the furnace. UV tube scanners use circa 1940s technology and fall victim to many issues not only with steam or water vapor, but also from x-rays, gamma rays, UV from the sun, and spark pick up as well. Flame rods can short circuit or oxidize to the point where a flame signal is no longer transmitted through the flame. A faulty flame rod circuit will trip the pilot and prevent operations from starting up the burner. ; Optical flame scanners offer more reliable flame detection than a flame rod. This paper will discuss the advantages of a particular solid state sensor and its ability to convert flickering UV radiation, pulsing from a burner‘s flame, into electrical signals. It will also discuss the technical and operational advantages of optically detecting UV radiation, versus the use of traditional flame rods. The paper will also address various solutions for combatting the multitude of shortcomings with a UV tube system, and existing issues of using other types of solid state sensors and their associated microprocessors