Performance Assessment (Thermodynamic)

Field Evaluation of Compressors, Pumps

Wood provides performance assessments on: compressors, engines and turbines, pumps, and other rotating equipment.

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1 Performance Assessment of Reciprocating Compressors and Engines

For maximum reliability of reciprocating compressor packages, equipment owners implement periodic performance and condition assessments (for the compressor and engine). Typically, the performance analysis involves a one day site visit with additional time for set-up, travel, and post-processing of data. A portable analyzer is used to collect performance data, including the pressure-volume card data from compressors and engines.

1.1 Scope

• The equipment owner will provide information about the unit (to set-up our analyzer and investigation).
• The operator or mechanic will install valves on compressor cylinders prior to the visit.
• Wood will capture mechanical and performance data during the site visit. Wood will compare the actual operating results with the theoretical performance model for early indication of problems and will include these performance and condition indicators:
  • Power and load, capacity
  • Efficiency
  • Leaking valves and rings
  • Improper valve dynamics
  • Crosshead and rod knocks
  • Power cylinder combustion
  • Vibration of accessories and frame
• Wood will prepare a detailed performance report for the unit, providing a valuable baseline for future assessments.

Performance analysis on offshore reciprocating compressor		Beta Field Analyst using B-Probe. Fast inspection identifies condition of bearings, wrist pin, and internal condition.

1.2 Option: Engine Bearing Assessment

• This is a non-invasive method to assess the wear on internal bearing and components and avoid expensive (and often unnecessary) engine overhauls.
• Operators can avoid excessive maintenance costs and potential crashes by checking:
  • Wrist pin and rod bearing clearances (wear and trend)
  • Cylinder leakage rates
  • Power cylinder condition & wear: liners, rings, ports, head, valves
  • Valve sink and train setting
  • Cylinder condition rating
• The internal inspection requires only a short shutdown (typically, four hours) to collect this valuable data. This is a fraction of the cost of an overhaul.
• The assessment uses Wood’s patented B-Probe (sold under license by Windrock and called the E-ProbeTM engine inspection tool).

1.3 Results

Here are some example savings:

• Created savings of >$3 million for a US gas transmission company by postponing overhauls of seven units
• Prevented failures that would have resulted in >$1 million damage
• Identified significant performance improvement opportunities due to valve dynamics problems resulting in incremental production exceeding $millions/year
• Allowing more targeted engine overhauls resulted in 80% cost reduction
• Extended the period between overhauls and identified overhaul requirements based on the unit’s condition

1.4 Examples

Performance Monitoring Examples: read more

2 Performance Assessment of Turbines/Centrifugal Compressors

Wood conducts performance analyses for other rotating assets, namely centrifugal compressors and gas turbine trains. Site testing and performance modeling techniques are used to determine key reliability criteria, including:

• Compressor head flow and efficiency
• Gas turbine air mass flow and firing temperatures, including  T5 spread and deviation
• Performance deviations over time

Example: A gas field was projected to be depleted within 18 months and the equipment owner wanted to avoid replacement or overhaul of the gas turbine. Wood conducted a detailed performance and vibration assessment of the complete gas turbine and centrifugal compressor system. The gas turbine was in acceptable shape to last the required time as long as it was regularly washed. The analysis did point out that the power turbine was in poor shape and that the compressor system needed booster compression to avoid surge. As a result, the client conducted an overhaul of the power turbine and installed additional compression for the remainder of the area’s production life.

More examples: Centrifugal Compressor Performance (pdf)

3 Wood Advantages

• Dedicated team of field analysts and engineers with performance and dynamic analysis experience offers combination of troubleshooting and performance analysis – a  valuable advantage for many projects and sets Wood apart from route-based vibration technicians
• Independent advice (vendor neutral)
• Technology leaders and inventors of Recip-Trap™ engine and compressor analyzer still remain at Wood. This experience is utilized in our field and performance monitoring groups.
• Integrated service of coordinated performance inspections with pulsation/vibration assessments is only offered by Wood.

Centrifugal performance testing & assessment in the Middle East

4 Related Information

• Performance MONITORING EXAMPLES
• Centrifugal Compressor Performance (pdf)

5 Key Words

• Recip-Trap Analysis
• Compressor Performance Inspection