Reciprocating Compressor Instrumentation and Condition Monitoring

2362221720819 1891710168

15 14 138

1.
2.
3.
4.
5.
6.

1211

Main bearings
Crankshaft
Crankpin bearings
Connecting rod
Crosshead pin
Piston rod locknut
7. Piston rod
8. Cooling water
9. Suction valve
10. Suction plenum
11. Cylinder head (outer end or head end)
12. Chamber (outer end or head end)
13. Discharge valve
14. Discharge plenum
15. Wear bands (rider rings)
16. Valve cover
17. Piston rings
18. Piston
19. Chamber (frame end or crank end)
20. Cylinder head (frame end or crank end)
21. Pressure packing case
22. Intermediate partition packing
23. Distance piece
24. Oil wiper packing
25. Frame

Rounded heel• Does the trend of a particular suction valve
temperature indicate a rise compared tothe other suction valve covers?

• Does valve cover acceleration/ultrasonic show

Cylinder valve temperaturehigh amplitude when suction valves are closed?

• If CE chamber: does the trend of the pressure
packing temperature (or flow) increase?

Cylinder valve temperature
Packing vent line temperatureCylinder acceleration

Packing case temperature

Pressure versus volume(crank end shown, head end similar)
Indicated pressure
falls slower thantheoretical on expansion
stroke (if theoreticalcurve uses cylinder
nameplate clearance)

Main bearing temperature
Frame vibration

Supporting evidence• Is flow balance less than 0.95?

TDC

BDC

TDC
02700TDC

30360• Does acceleration/ultrasonic show highamplitudes when chamber pressures different
and low amplitudes when chamber pressuresare equal?

Indicated pressure crosses
theoretical pressure(both chambers)
BDCTDC

4/14/2019
7:00:00 PM

4/14/2019
7:20:00 PM
5 min/div

4/14/2019
7:40:00 PM

4/14/2019
8:00:00 PM-50000

Sample atbreak a few
seconds later 100 µm/div

090

18030°/div

270

Rod reversal
The shortest distance, measured in degrees of crank revolution, between each change
in sign of force in the combined rod-loading curve.

TDCBDCTDC

0Suction
90Compression
18030°/div

Discharge

270

360-0.706 g @ 0°

Crosshead-mounted accelerometers can detect machinery problems due toimpact-type events such as loose running gear components, liquid ingestion
into the cylinder, or excessive clearance in the wrist pin bushing.

0

1/1/2017
6:00:00 PM

1/8/2017
6:00:00 PM

1/15/2017
6:00:00 PM

1/22/2017
6:00:00 PM

1 day/div

1/29/2017
6:00:00 PM

12.497 g pk @ 360 rpm 1/16/2017 4:43:25 AM

Crosshead acceleration—band waterfall with 36 software bands
19

4.78

0.04

15
105g pk

100% load
75% load

1/28/2017 3:05:46 AM

360

1/22/2017 10:56:56 PM
1/20/2017 8:52:59 AM

360

25% load-100,000

1/25/2017 1:01:51 PM

358

50% load2000

Rod reversal

24

9.25

100 psi (g)/div

Tension

Expansion

3214.262500

0-50,000-435TDC

A value determined by the OEM based on the design limits of the static components(frame, distance piece, cylinder, and bolting).

50,000 lbf/div

Maximum allowable continuous gas load (MACGL)

Compression

A value determined by the original equipment manufacturer (OEM) based on design
limits of the various components in the compressor frame and the running gear( bearings, crankshaft, connecting rod, crosshead assembly, piston rod, piston assembly).

50,0002-215CAPACITY CONTROL STEPLESS UNLOADER

Red gas load
Blue combined load
Combined load

40Crosshead acceleration—six hardware bands

Even during different load steps, the comparison between theoretical and measured pressures is available, due to apatented algorithm to determine suction valve closure with no input required from dynamic valve unloader controller.

100,00001 g pk/div

Combined (inertia and gas) rod loads calculated at the crosshead provide information
about the lubrication condition of the crosshead pin. Insufficient reversal or excessiverod load can be identified and corrected before costly running gear damage occurs.

Waveform types

360

ROD LOAD MONITORING

48

10-2-100000

56

CONDITION MONITORING

Head-end theoretical pressure curve
Head-end indicated pressure curve
Crank-end theoretical pressure curve
Crank-end indicated pressure curve

BDC

4/14/2019
6:40:00 PM

04

1 g pk/div

024

500 1000 1500 2000

20

HE discharge valve closes
HE suction valve opens
HE suction valve closes
HE discharge valve opens

12

The process stages are for the HE chamber• Is discharge temperature elevated comparedto adiabatic discharge temperature?

0.4 g/div

010,000 lbf/div

1000

500

1.
2.
3.
4.

• Is flow balance on both chambers
greater than 1.05?

50000

180100 µm pp/div

1500

4

Supporting evidence

LOOSE PISTON

Rod break ~1900 µm pp

Maximum allowable continuous combined rod load (MACCRL)

Our machinery diagnostic engineers help
you reach your safety and efficiency goals,
increasing uptime, while reducing operationand maintenance costs.

18030°/div

43
2
1Inter-chamber leak

2 g/div

2 bar (g)/div

TDC

BDCTDC

20 µm pk-pk/d

100 µm/divTrend of rod position peak to peak value in horizontal and vertical direction

90120

For more information visit
bntechsupport.com
or call +1 775 215 1818036060

Recip Mulit-Event wheel kit(Part No. 146973-01)
Custom Recip Multi-Event band(Part No. 105M5964-xx)

For each 10° CA, the 0-pk value of theacceleration signal is calculated

Theoretical pressure curve
Indicated pressure curve-20-1000

Sensing multiple events per revolution is thetechnique used with the Bently Recip Multi-EventWheel.

• Does valve cover acceleration/ultrasonicshow high amplitude when dischargevalves are closed?

-1030

A pressure transducer installation suffering fromchannel resonance will show pressure fluctuations
when the suction and discharge valves are closed
as well as whenthe valves are opened. The frequencyof this resonanceremains nominally constantthroughout the cycle.

CYLINDER ACCELERATION OVERLAID WITH DYNAMIC PRESSURES

temperature indicate a rise compared tothe other discharge valve covers?

Pressure versus volume040

Channel resonance on pressure
versus displaced volume curve• Does the trend of a discharge valve

Inter-chamber leak (usually piston rings)

1050-500

The torsional vibration of the crankshaft changes
from revolution to revolution for each load step on
the machine. Having multiple events per revolution
improves the ability of the system to capture datawith respect to crank position, regardless of the
shape or change in shape of the torsional vibration.

AA typical indicated cylinder pressure curve will havesome pressure fluctuation when the suction anddischarge valves are opened. The areas labelled“A” and indicated by braces show these pressure
fluctuations. When the valves are closed, thepressure shows a smooth line.

Revolution when rod is disconnected (piston rod broken)

700 µm pp

270

The single most effective way of determining the overall health of a reciprocating gas compressor is by examining
the cylinder chamber pressure profile. Online access to the internal pressure for each compressor chamber
enables continuous monitoring of chamber pressures, compression ratios, peak rod loads, and rod reversal.
This provides valuable information on the condition of suctionvalves, discharge valves, piston rings, packing
glands, and crosshead pin.

Typical pressure versus displaced volume

Leak from high pressure reservoir

Rounded toe

18030°/div

for high temperature
resistanceA

Leak to high pressure side (discharge valves)

Cylinder pressure

600
400
20090

Cylinder pressuretransducer (± 0.5% accuracy
for 1+ billion cycles)

APISTON ROD BREAK

0• Gold-plated diaphragm for

Crosshead vibration

Cylinder pressure

One revolution of rod position waveform in horizontal and vertical direction

Benefitabsolute pressure reference

Frame vibration

Crosshead pin bushing

0Mechanical bracing toprotect cylinder pressuretransducer• Evacuated transducer for

Theoretical pressure curve
Indicated pressure curve

Multi-event Keyphasor® system500• Tested to over 2 billion cycles

Suction/Discharge temperature

Indicated pressure rises
faster than theoreticalon compression stroke

MULTI-EVENT WHEEL

Design features• Separate electronics module• Is flow balance greater than 1.05?

Indicated pressure rises
slower than theoretical oncompression stroke

Isolation valve (should notinduce channel resonance)

corrosion resistance

Supporting evidence

Indicated pressure falls fasterthan theoretical on expansion
stroke (if theoretical curve uses
cylinder nameplate clearance)

Crosshead assembly nomenclature

Lubricating passage

Leak to low pressure reservoir(crank end shown, head end similar)

Crosshead shoe
Crosshead

Crosshead pin

Cylinder pressure transducer

Pressure versus volume

Horz-vert piston rod position

Connecting rod

Leak to low pressure side(suction valves or pressure packing leak, if CE chamber)2 bar (g)/div

24

5

TDC

25

4

BDC

3

CYLINDER PRESSURE INSTALLATION DETAILS

TDC

2LEAK

0.2 g pk/div

1

INSTRUMENTATION LAYOUT

0.5 g/div

COMPONENTS AND NOMENCLATURE

1/17/2017 6:49:05 PM360

1/15/2017 4:45:09 AM
1/12/2017 2:40:14 PM360

1/5/2017 4:45:00 AM-150,000

090

18030°/div

2703601500

0102030

40501%/div

6070

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8090

10009018030°/div

27036016.342 g pk @ 45°, 360 rpm