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Bryan Blanchard, Senior Analyst, Windrock, Inc.

Windrock Users Group Conference 2017

IHP Losses From Valve/System Loss and How to Determine Which

is the Cause

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Outline

Theoretical Valve Losses Factors that affect Theoretical Valve Losses

Actual Valve loss Losses due to cylinder load conditions Losses due to pulsation

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Compressor ReportValve losses

• Horsepower is how we will measure valve and piping losses

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Compressor Losses

It takes WORK to move gas in and out of a cylinder and through a pipe. WORK is the area inside the PV curve; the rate of doing work is HP.

Calculating Horsepower

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Theoretical Horsepower

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Horsepower Loss

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Compressor Valve TheoryGas Movement Out of Cylinder vs. PV Card

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1000

1250

1500

1750

2000

2250

0 25 50 75 100

Pressure

(psig)

Percent swept volume

Theoretical Discharge Pressure

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How Do We Verify The Software’s Decision?

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Verifying Computer Generated Toe PressuresNormal - Nozzle pressures or panel gauge readings

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Effects on Theoretical Toe PressuresTDC Issue

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Effects on Theoretical Toe PressuresSmoothing

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Effects on Theoretical Toe PressuresLeaking Valves/Rings – Crank End Suction Valve Leak

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Effects on Theoretical Toe PressuresLeaking Valves/Rings – Crank End Suction Valve Leak

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Losses Due To Valve Issues

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Magnitude Of Losses

Factors affecting the magnitude of losses are:– Valve Design– Suction and Discharge Pressure– Suction and Discharge Temperature– Compressor Speed– Gas Composition– Suction and Discharge Piping Design– Compressor Passage Design– Clearance Area– Foreign Material in Valve

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Where To Sample Data?

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Normal Pressure OverlaysNozzle Pressure – Orange Cap Pressure - Black

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Compressor Valve Loss

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Compressor Valve Loss

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Losses Due To Clearance Issues

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Theoretical vs. Nozzle Pressure – Head-end Pocket OpenAdded Clearances on High Speed Compressor

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Theoretical vs. Nozzle Pressure – Head-end Pocket OpenAdded Clearances on High Speed Compressor

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Losses Due To Pulsation Issues

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Pressure waves caused by the suction and discharge events in thecompressor ends Can cause vibration in piping Easier for gas to flow in through the suction than the discharge Vibration may be extreme if the pulsation coincides with:

– the acoustic resonance frequency of the piping– the mechanical natural frequency of the piping Affects compressor performance

– when valves open and close– volumetric efficiency (capacity)– HP consumed moving gas Easier for gas to flow in through the suction than the discharge

Pulsation Losses

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500

550

600

650

700

750

800

850

0 45 90 135 180 225 270 315 360

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- Scale 2.074 DGF

- Scale 2.050 DGF

- Scale 2.076 DGF

- Scale 2.091 DGF

- Scale 2.092 DGF

- Scale 2.091 DGF

1HS3 VT1

1HS2 VT1

1HS1 VT1

1HD3 VT1

1HD2 VT1

1HD1 VT1

Pres

sure

(psi

g)

Crank Angle (deg)

Pressure in discharge nozzle

Pressure in suction nozzle

Pulsation Nozzle Pressure Trace

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Total HE IHP = 514 IHP

550

600

650

700

750

800

850

0 25 50 75 100

Pres

sure

(psi

g)

Percent swept volume

Pulsation Total Head-End Power

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Theoretical IHP = 421 IHP

550

600

650

700

750

800

850

0 25 50 75 100

Pres

sure

(psi

g)

Percent swept volume

Pulsation Theoretical Head-End Power

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550

600

650

700

750

800

850

0 25 50 75 100

Pres

sure

(psi

g)

Percent swept volume

Total Discharge loss = 104 IHP, or 20%

Total Suction loss = -11 IHP, or -3%

Pulsation Total Loss From Theoretical

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Suction valve loss = 31 IHP or 6%

Discharge valve = 24 IHP or 5%

550

600

650

700

750

800

850

0 25 50 75 100

Pres

sure

(psi

g)

Percent swept volume

Pulsation Valve and Passage Losses

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Suction pulsation loss = -42 IHP

Discharge pulsation loss = 80 IHP or 16%

550

600

650

700

750

800

850

0 25 50 75 100

Pres

sure

(psi

g)

Percent swept volume

Pulsation Pulsation Losses

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Valve and System Loss Summary

Observation Typical CharacteristicsExcessive Valve Loss

• Valve and passage loss calculated from the PV > 10% (rule ofthumb).

• Valve lift or flow area insufficient.• Foreign material in plates or valve area.• PT and PV curve appears rounded during the suction or

discharge phase.• Verify with nozzle pressure as close as possible to the valve

Passage or System Loss

• Flow area of nozzle, orifice, bottle, piping or cooler is insufficient.• Unwanted bottle/piping pulsation.• Clog suction screens.• Collapsed bottle baffle.• Verify with nozzle pressures throughout the piping system.

Thank you!