THE FIRST 0.2 SECONDS OF BLACK LIQUOR DROPLETS INSIDE A RECOVERY BOILER FURNACE, 2010 TAPPI/PAPTAC International Chemical Recovery Conference

Please Note: This document will be available in PDF format in the "My Electronic Documents" link on the home page once your order has been completed. Please make sure you have the latest version of Acrobat Reader. Click on the Acrobat Reader icon to check for the latest version, it’s FREE. To print a hardcopy of a PDF file correctly you must have a postscript printer. If you are not sure if your printer is a postscript printer please refer to your owner’s manual.

Black liquor spray droplets - especially their initial stages - were studied inside a recovery boiler furnace using a new optical probe developed at Aalto University (TKK). The arrangement allowed measurements at different locations as far as 2.3 meters from the nozzle. Droplet formation in furnace environment process was found to be different compared to earlier expectations. One essential finding was the droplet explosion caused by flashing. A part of the energy accumulated in the high solids content black liquor in the form of excess temperature (temperature difference between black liquor spraying temperature and boiling point) A part of that energy was released in the nozzle pipe as increased spray velocity. A second part of steam formation seemed to take place inside spray droplets and expanded them. Hollow particles, which have very thin surface, could be detected at the distance of 2.3 meters from the nozzle. These particles will break very soon to smaller particles. The timescale of the formation of hollow particles is less than 0.2 seconds after they have left the nozzle. Another interesting new phenomenon was the existence of burning or partly burning particles at the distance of 2.3 meters. Ignition of spray droplets seemed to take place much faster than expected earlier.