Need to prove VFD is superior to dampers RE Air Flow modulation 1

[s0eebuch]

All,

Trying to sell a customer on a VFD versus a butterfly damper that is currently installed downstream of an industrial blower. Customer won't let me gather onsite data or conduct any tests, but is willing to look at the 'facts', as he put it. He said, if I can prove on paper that a VFD is better than a butterfly damper and if he can justify the upfront costs, then he'll consider it. Any ideas?

s0eebuch

 

[StoneCold]

Soeebuch

This article from Reliance addresses that issue

http://www.reliance.com/prodserv/standriv/d5061.htm

 

[25362]

The Buffalo Forge Company's Fan Engineering handbook, when dealing with power saving on Chapter 15, Fan Control, says, I quote:

The very impressive savings that can be achieved with variable pitch and variable speed are comparable, especially when slip losses are included in the variable-speed application. End of quote.

 

[btrueblood]

Variable-pitch fans and butterfly dampers aren't the same thing. Variable-pitch fans are a means of modulating power consumption of a fan at (relatively) constant speed. Variable speed fans modulate power by changing fans speed. Butterfly dampers are essentially flow control valves operating downstream of the fans. Dampers modulate airflow by causing a pressure drop (aka loss), and as such always represent a power consumption at any but full open position; i.e. the power consumed with damper-modulate systems will not change, it will always be high.

 

[jsummerfield]

Watch the distance issues. Additional electrical equipment may be required if the distance exceeds about 400-foot. It is not real costly but an additional consideration.

John

 

[25362]

The quotation I brought from the Fan Engineering handbook wasn't meant as a comparison on flow control by the use of downstream dampers, but only to mention another control method that could economically compete with VSD, which was the leitmotiv of the original post.

BTW, other -not as efficient as VSD- flow control methods that may be worth mentioning are:

* Inlet-box Dampers (IBD)
* Variable Inlet Vanes (VIV)

 

[s0eebuch]

Thanks for all the posts. I have done work with packaged boilers and am familiar with Inlet Vane Control Dampers (IVCs) and the like, but never did any work with variable frequency drives. Customers just didn't like the upfront cost and, if dampers worked, why not use them (customer's train of thought, not necessarily mine).

I'll post what the final outcome of this issue becomes.

Thanks again.