2 replies to this topic

[Lyne]

I’m trying to understand if two dissimilar discharge check valves are required downstream of a single-stage centrifugal compressor. From what I’ve read, reverse flow typically occurs during a compressor trip  in case of multistage compressors or parallel trains.

[Pilesar]

Two check valves would be reasonable. Required? I don't know. If you were responsible for NOT having two check valves and there were problems later, where would the fingers point? "Look at all this damage but he saved the cost of a check valve."

Consider this link:  https://copilot.micr...eZNoEeREY2w4rmL

[astro]

Why is a non-return valve required at all?

 

Put yourself into 1 person HAZOP mode and with that mind set game out the potential hazards to the process of a reverse flow scenario.  Without an explanation of those issues, it's difficult to provide useful comment at a distance.

 

When the design reaches the point that it is ready for workshop level scrutiny, then a HAZOP will investigate this question in depth.

 

If it turns out that reverse flow is not a big deal, then an NRV is not necessary. For a centrifugal compressor, before the process reaches true reverse flow conditions, the key issue is low flow at the point where the machine surges. Surge can be thought of as a repetitive forward-reverse-forward flow cycle and is commonly addressed by an anti-surge control system to avoid machine damage.

 

If surge control is included in the design, an NRV may not be that important.

 

Have a think and then share your thoughts with a bit more detail and depth noting the points raised above.