Coal pulverisers typically have a guillotine style isolation damper installed in the primary air ducts. This duct work can be round, square or rectangular in shape. They are usually small in diameter or size depending upon the size of the mill and the size of the unit. These isolation dampers are used to cut off the flow of hot air while the unit is running so that maintenance can be performed on the mill while the unit is on line. Unfortunately these isolation dampers do not always seal properly due to age or binding. Care should be taken to ascertain the operating temperature in the area where the duct balloon will be installed as this maybe higher than what our high temperature material is rated for which is 500ºF (260ºC).
Duct balloons are typically supplied in a 3’0” thickness. In the coal pulverisor application, this thickness may not always work due to clearance problems such as a tight radius in round ducts or stiffeners inside square and rectangular ducts. Also, a check should be made to see if any flow monitoring instrumentation could be in the way of where the duct balloon would be installed. In this case, it can be made thinner, sometimes a little as 10” and still perform well.
Duct balloons are typically supplied in a 3’0” thickness. In the coal pulverisor application, this thickness may not always work due to clearance problems such as a tight radius in round ducts or stiffeners inside square and rectangular ducts. Also, a check should be made to see if any flow monitoring instrumentation could be in the way of where the duct balloon would be installed. In this case, it can be made thinner, sometimes a little as 10” and still perform well.
The material used in this application is the same material that is used on turbine covers and carries a NFPA 701 fire rating.
This one measures 70” wide x 24” high x 12” deep for use in the primary air duct of a coal pulverisor during maintenance of a broken off pyrite plow. Note that the inflation tube is attached to the 12” deep side wall to permit installation via the existing access door.
Here is a 41” round x 29” thick duct balloon that will be used on the primary air duct of a CE 983 pulverisor during mill maintenance
This duct balloon comes with 25’ of 8” flex duct so that blower can be located away from the work area
Copyright 2010 by G.R. Werth & Associates, Inc. - All rights reserved
Duct Balloon
Inflatable Isolation Barriers
