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Can you comment on some of the most important aspects of recent orders for compressors and turbines? Also, with a large backlog of orders for new equipment, what are the most effective condition-monitoring and asset reliability programs for maintaining the performance of existing rotating equipment?
 
Answers
18/07/2008 A: Yakov Feldshteyn, Compressor Controls Corporation, yfeldshteyn@cccglobal.com
As with most mechanical devices, the performance of a turbine, compressor, or other rotating machine depends on design characteristics that slowly deteriorate. That degradation can be quantified by comparing the relationships between various process variables to those that existed when the equipment was new. If a turbocompressor is operated at a constant compression ratio, for example, blade fouling will decrease the flow rate at any given speed. Such degradation can then be quantified by comparing the current flow rate to that a new compressor would produce at the same speed. Our company developed the Parametric Diagnostics System (PDS) - a Unique Software for Monitoring, Projection, and Diagnosing the Degradation of Turbomachinery and Auxiliary Equipment. PDS was successfully tested and released to a customer base of more then 50 turbomachines worldwide.
A unique set of software components that can be integrated into a TrainTools HMI system to:
- monitor, calculate, and record diagnostically relevant process variables;
- use statistically-derived process models to calculate the values various parameters would have had in the absence of any degradation;
- display and record the deviations of those parameters from their modeled values;
- analyze deviation trends to diagnose existing and predict developing problems;
recommend appropriate corrective actions and preventative maintenance schedules.
The highly-adaptable PDS modeling engine can be applied to turbines, compressors, expanders, generators, pumps, blowers and most auxiliary systems. Because its mathematical models are statistically developed from recorded measurements, OEM-supplied data is not needed. In many cases, the only inputs required are those used for process control and protection.
Implementation of such a system can increase your unit’s profitability by maximizing energy efficiency, minimizing downtime, optimizing maintenance intervals, and extending equipment service lives.
To find more - http://www.cccglobal.com/software/pds/
21/07/2007 A: Eric W Hennings, Stone & Webster Engineering Corporation, eric.hennings@shawgrp.com
One potential problem on steam turbines is longer-term loss of efficiency due to deposits on the turbine blades. In the extreme case, the turbine horsepower can become an equipment limitation. On many units, “attemperation” of high-pressure steam uses boiler feed water, which is readily available. This water contains minerals, which contribute to fouling of the turbines. This situation can be improved by using a separate system to deliver demineralised water to the superheated steam.
21/07/2007 A: John Farrow, Foster Wheeler Energy, john_farrow@fwuk.fwc.com
As plant sizes increase and end users maintain a strong preference for 100% rather than 2 x 50% compressors/turbines, we find we are selecting equipment larger than anything previously supplied.
To meet these requirements, we have had to assess the critical areas for the increased size and break down the rotating machinery into component experience. In this way, we try to ensure that reliable equipment is purchased with proven component experience.
To further mitigate the risks, we have worked closely with process engineers to modify their ideal solution to fit in with selection of minimum risk/commercially viable equipment. We have also specified vigorous inspection and testing requirements.
To maintain plant availability and efficiency, we specify strict monitoring of performance and a two-out-of-three rating on trips to avoid spurious plant shutdowns. We have also provided “washing” facilities to maintain equipment and hence enhance plant efficiencies.
As well as on-site monitoring, many compressor/turbines can be assessed back at the manufacturing facility for review by vendor specialists. This requires satellite transfer of operating parameters back to the factory. This can help with trending, preventive maintenance and unscheduled shutdowns.