We have a non-API reciprocating copressor where pulsation in piping is above limit in all speeds in operating range.

How can we calculate whether the compresor suction and discharge volume bottles are smaller than required or not - is not it so that larger the volumes - better the pulsation reduction ?

Presently, piping stiffness are raised by stapping the piping by clamps all around and reducing mass by using light weight valves - stronger fatigue resistant piping connections are thought of.

But, can we prove that there is no low hanging permanent solution in mechanical intervention and acoustic pulsation damper with larger volume bottles will be permanent solution ?

reg,
sam

1. Decide what pressure differential is acceptable. Presumably you already know what that is.
2. Calculate dV/dt (change in volume versus time) as a function of cylinder volume and RPMs for the entire cycle of the compressor. Note that dV/dt for a single cylinder is maximum at mid-stroke.
3. Estimate pressure losses in piping and pulsation bottle as a function of these velocities. dPloss/dt. Ensure nozzle connections aren't acting as choke points.
4. Use these values in estimating dP/dt•dV/dt=dZ/dt•R•dT/dt.

You should be able to get dT/dt from field experience with the device.
Compressibility is probably constant, but if you know the fluid, you should be able to find this information.
You know dV/dt from step 2 above.
Solve for dP/dt.

You now have a curve that depicts what your pulsations look like.

Thank you!

I have found an API Sprc 11P bottle sizing chart

where suction and discharge bollle sizes are provided

V = A× SV
Where: V = minimum required surge volume
SV = swept volume
A = Multiplier as determined from the chart

This factor A is 5 & 7 for suction & dischage bottle sizes for 20 barg pressure and 7 and 9 for suction & dischage bottle sizes for 80 barg pressure.

API 618 4th Ed Sec 3.9.2.2.2 have formulae for suction and discharge bottle sizing, too!

reg,
sam

Dear Michael,

Your approach is right. But, tolerable pressure fluctuation and heat transfer occuring in surge volume - something in between isothermal and isentropic process makes this approach a bit flexible in selecting the surge bottle sizing.

In the centinary year of Richard Phillips Feynman, we remember why US is great - not due to wealth, but due to Science!

In every step of our work we use application of physics whis Feynman made so interesting!

reg,
sam