Designing a Vacuum System

[StevoSimpson]

Hi,I'm in the middle of a project which concerns increasing the efficiency of a couple of Paper Machines.
We are at the moment concentrating on the vacuum pumps, and I have just worked out the needed power factor correction to increase the efficiency.

Currently there are 7 vacuum pumps used to draw off the water before the paper enters the press section.

However, someone has suggested that by using one large pump and a backup. Now, I am entirely unsure about how to go from here - do I need to sum the capacity of the smaller pumps to come up with the needed capacity of the bigger one? similarly with the pressure? Also, since I need differing pressures on the output, how do I go about seperating them?

Ive tried to find information on the internet, but I can't find much, if anything, about vacuum systems, just the pumps themselves. Any help would be much appreciated.

 

[FACSITEDEV]

Air is compressible. Manifolding air to differing vacuum pressures dynamically will require automated controls. The cost of the automatic controls and SCADA to monitor them is more than the cost of seven individual vacuum pumps, but if you're having the control problems with the process anyway, it's one possible solution. As fast as paper machines run, you'd have to have one heck of a skookum controller system!
Maybe you can use nano-vacuum pumps, hundreds per press? %)

 

[rmw]

http://www.graham-mfg.com

has a vacuum pump sizing program called vacworksII that I think you can get from contacting them via their site.

You could run some test cases with that program.

rmw

 

[StevoSimpson]

Thanks for the replies.

I've contacted

http://www.graham-mfg.com

and should receive the software in a few days. I shall also be contacting Nash to see what they say about the likelihood of this working, or whether I should just go a completely different route. (maybe not nano-vacuum pumps though! ;-) )

I'll let you know what the results are.

 

[quark]

When you have to maintain different pressures, I suggest to go with multiple pumps. Ideally, the capacity of bigger pump is the sum of all the small pumps. Minimum quantity of noncondensable gases may be a problem when you deal with bigger vacuum pumps(liquid ring type), particularly at low loads. You can download good articles about vacuum system design from

http://www.dekkervacuum.com/reference/index_frame.htm

There is one good link of sterling fluid systems, I have been referring to for quite some time in these forums. Do a keyword search on vacuum pumps and you can get it.