FURNACE CLEANLINESS MONITOR FOR HIGH REFLECTIVITY ASH

A method and apparatus for monitoring reflective ash deposited on a furnace wall to be cleaned, comprises an infrared video camera or other mechanism for taking an infrared image of the furnace wall. The image must include an area to be cleaned by the waterblowing as well as a surrounding uncleaned area. Photo detectors or other mechanisms are utilized to measure the image intensity at locations on the cleaned and uncleaned areas with a ratio between the intensities being taken. The cleaned area has low reflectivity and is dark compared to the uncleaned area which is white and has high image intensity. The image intensity ratio between the cleaned area and the uncleaned area thus rises from a low level immediately after waterblowing to a high level which approaches unity as the initially cleaned area becomes as unclean as the uncleaned area. This can be used as an indication when waterblowing must be manually initiated, or the ratio signal can be used directly to operate an automatic system to initiate waterblowing.