CCJ ONsite: '12 CTOTF Fall Turbine Forum

Update #3

 

Generators an emerging reliability issue for combined-cycle systems


Don Schubert, Senior VP, March Energy Practice, told attendees at CTOTF's™ Fall Turbine Users Conference last week in San Diego that generators accounted for 16% of insurance losses for 2011-exceeded only by heat-recovery steam generators (18%) and gas turbines (28%). This probably surprised some in the room; the reliability of generators typically has been "taken for granted" by the industry. But eight generator losses last year, attributed primarily to slot movement and end-turn vibration exacerbated by cycling, point to the need for closer attention by plant operating staffs. more 

GT upgrades can adversely impact HRSG performance, life

 

Scott Wambeke, PE, one of HRST Inc's (Eden Prairie, Minn) most experienced HRSG troubleshooters, had a simple message for gas-turbine (GT) owner/operators attending CTOTF's Combined Cycle Roundtable last week in San Diego: Don't opt for a GT upgrade before conducting an engineering evaluation to see if your heat-recovery steam generator will meet expectations with the new operating parameters. more
 

GT issues: They may not cease to challenge until your unit is scrapped

 

All gas turbines are unique, despite model numbers that might argue otherwise. In engineering school students were introduced to the bathtub curve-at least they were decades ago. The basic idea was that after a relatively short break-in period component reliability remained virtually constant until end of life, when it dropped off the proverbial cliff. Most students didn't pay much attention to the word "component" and fewer still probably read the fine print, which talked about the general applicability of the curve to electrical and electronic components, but not to complex systems. more

 

7FA ring fire suggests shift from peaking to base-load duty is not as simple as just running longer

 

The day after the CTOTF meeting ended, and the morning after NEC's W Howard Moudy spoke to attendees about the risks associated with ignoring OEM-suggested maintenance of exciter collector rings and brush systems, Cutsforth Inc's Senior Application Specialist Steve Thompson called to report a damaging ring fire that required immediate attention. Plant personnel told Thompson the fire was so intense that material literally blew out of the housing, as evidenced by the holes shown in the photos. Cutsforth normally is able to repair/refurbish/upgrade brush rigging onsite, but the severity of the damage here was such that the entire housing required a shop visit for a complete rebuild. more 

Tip-cap loss on 7FA first-stage turbine buckets found by borescope inspection

 

As borescope technology improves and inspection teams gain ever more experience, there seems to be no end to the type of deterioration mechanisms and damage that can be profiled without lifting the turbine upper casing. Rod Shidler and Mike Hoogsteden of Advanced Turbine Support LLC talked to the editors at one of the busiest CTOTF Fall Turbine Users Conferences in years about the correlation they believe ATS inspectors have identified between the loss of 7FA first-stage bucket tip caps and the loss of coating from the leading edge of the airfoil or the loss of the bucket's entire leading edge. more 

 

       

 

    

 

     

 
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