×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Compensation valve compressor/expander combination

Compensation valve compressor/expander combination

Compensation valve compressor/expander combination

(OP)
In our plant we have a few compressor/expander combinations to produce cold.
The expander is driving the compressor.

One of this combinations has a "compensation valve" the use of this valve is clear. At the start-up it compensates the axial forces who are generated by the expander, since the compressor is still running in bypass and does not create his own axial forces to compensate the ones of the expander.

Ok, that's clear to us. Now I have a question. Why has only this particular combination the "compensation valve"? The others don't have one.

We are thinking it is that because this machine is running on much higher pressures then the others, but also this one is the oldest combination we have, so it can also be something which is used in the past.

Does anyone know the answer?
Thanks,
Cryotechnic

"Math is the ruler of your potential succes...."

RE: Compensation valve compressor/expander combination

Can you describe how this valve is piped in to the expander process?  Do you also have a recirculation valve on the compressor-side of the unit?  Have you tried starting the unit without opening the valve?  Can you monitor the compressor-side bearing temps during startup?

RE: Compensation valve compressor/expander combination

(OP)
When the compensation valve is opened, gas from the compressor inlet is fed to a chamber where a piston (disc mounted on the shaft) is, and so creating a force with a direction away from the turbine.

There is no compensation valve at the turbine, and there is no bypass at the turbine.
There is only a bypass at the compressor.

I am not sure if it is possible to start the combination when the compensation valve is closed... I will check that.

What I do know is that we have to close the compensation valve manually after the start-up, so in that case it's possible to run the combination with the compensation valve opened. In my opinion, that's not a recommend situation, because then your actually have 2 forces (1 too many) on your compressor. Then you have the compensation force and your "normal" force.

It's a good point to check the temperatures of the bearings. We don't have a good read out since this machine is very old one, but we do have a temperature read-out. (too bad, we don't have a trending)

Thanks in advance,
Cryotechnic.

"Math is the ruler of your potential succes...."

RE: Compensation valve compressor/expander combination

(OP)
Ok, I checked the compensation valve. The valve opens automaticaly at low RPM's. (why they have choosen RPM's we don't know, our idea was: they have to let it switch on something.......)
So opening is automatic, closing is manual.

Cryotechnic

"Math is the ruler of your potential succes...."

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources