Duct Balloon®

   Inflatable Isolation Barriers - Since 1998

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The following are some installation notes and photos on a recent project for installing a HRSG Duct Balloon® inside the HRSG exhaust stack at the CEMS platform level on a 7FA Gas Turbine with HRSG

The plant has two GE Frame 7FA Gas Turbines. The exhaust stack is 17’6” (5.3m) diameter x 125’0” (38.1m) high. The CEMS platform level is at a 60’ (18.2m) elevation.

An access door was installed about half way up the stack which measures 2’6” x 2’6” (762mm x 762mm). Note the 2” (50mm) diameter stainless steel support rod above the door opening which spans the 17’6” (5.3m) diameter stack. The support rod was installed to stay permanently in place inside the stack after the balloon is removed. This installation location was chosen as it is below the existing CEMS equipment.

“Quick Link” type oval rings are attached to the support rod that will attach to the carabineers

Nylon rope is attached between the support rod and the anchor rings points which are sewn into the top surface of the Duct Balloon®.

It is now hanging inside the stack and ready for inflation.

As it starts to inflate, it expands off the ID of the stack near the access door and moves outward along the support rod. Inflation time is less than 3 minutes. Removal time from the stack takes about 5 minutes.

The 120V/60 high pressure blower must remain on continuously to keep the Duct Balloon® fully inflated. Our 1st generation design was typically installed inside the stack on a slight angle to permit water runoff towards the access door. If snow accumulates on the top of the Stack Balloon, it will quickly melt due to the residual heat from the HRSG rising from below. Our 2nd generation design has a sloped top surface with internal drain and is installed perpendicular to the stack.

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