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How can I justify a Stack Balloon purchase?

While there are definite cost benefits to prolonging the life of a HRSG by keeping the heat “bottled up” inside the unit during a lay up, the the HRSG Users Group are trying to come up with some hard numbers to help answer this question. We do know that customers in our area (No. Indiana, USA) have stated that justification was easily accomplished by the amount of fuel saved when comparing the different type of startup scenarios that their units encounter due to varying load demand. They stated that their startup times were reduced by ~30 minutes per startup by keeping the HRSG warm with the stack balloon versus no stack balloon. They also stated that with an ambient temperature of 20ºF (-6ºC), they were able to keep their HRSG about 100ºF with no sparging steam. By multiplying the amount of fuel saved that their units consume (for them it’s 600 MMBtu/hr) multiplied by the time saved in startup earned them a very quick pay back on their total investment of about $35,000 USD per stack.

Can you provide anything other than the Stack Balloon and blower?

We only offer the stack balloon and blower. Items like the access door, support rod, and hardware that is required to install the balloon in the stack can be purchased from vendors specializing in these items or they can be fabricated on site.

What advantages does a Stack Balloon offer compared to a stack damper?

Since a steel stack damper is installed in a vertical stack, it is always exposed to the elements. Corrosion starts to take place almost immediately and greatly shortens the life of the damper as seen here.

Can the Stack Balloon be automated to operate like a stack damper?

No, it must be manually inserted and removed but that thakes only minutes to accomplish.

 

Does the support rod remain inside the stack ?

Yes, but it can also be made removable if desired.

What kind of access door do you recommend?

The non-bolted kind works great. To see what one looks like, click here.  

Can I use an existing 24” round access door which is installed near the stack dampers to install and remove the stack balloon?

Yes, we have supplied customers with a special type of Stack Balloon that allows you to use this existing access door. Please contact us for details.

Can you offer any engineering services which maybe required?

We have directed customers to HRST, Inc. in the past for these services. You may contact them at (952) 833-1428 for more information.

How long does it take to install and deploy it?

After bringing the Stack Balloon up to the access door, it only takes about 5-10 minutes to hang it from the support rod, and then another 3-5 minutes to inflate it.

How long does it take to remove it from the stack?

After you turn off the blower, pull the deflation zippers open and it will deflate in less than about one minute. All Stack Balloons are provided with two deflation zippers as shown on the layout drawing. By using a quick opening access door, the total time to remove the Stack Balloon and close the door is about five minutes.  

We use dehumidification equipment during lay ups and vent moist air from the HRSG out the exhaust stack. How can I still use the Stack Balloon?

You need to specify a through hole in the stack balloon, which you can see by clicking here.

Where do most people place the blower during operation?

At the CEMS platform level, near the entrance point of the access door, or it can be located inside the HRSG building.

Can I leave the blower outside on the CEMS platform?

The 120V or 220V  blower is weather proof  (not waterproof!) and can remain outside, but you may need to build some type of shelter for it.  

We have stack dampers but they are a real maintenance headache. Can I put a Stack Balloon on top of an existing damper?

In the case of a stack damper, you should remove everything except the existing damper blade supports before installing the support rod and support hardware.

Can we use silencer sound baffles inside our exhaust stack to support balloon?

Yes, the sound baffles make an excellent support system for the a Stack Balloon.

Where do most people store a Stack Balloon after they remove it from the stack?

Most users store it near the access door in the supplied vinyl storage bag