Focused OEM and third-party supplier presentations and a robust vendor fair are the foundation of user group meetings. Important to success is the involvement of the steering committee in selecting topics of current importance to the membership and in the review of these presentations beforehand to assure they have technical value.
Committee members also facilitate the open discussion sessions, maintaining subject focus and contributing experience as necessary to assure attendees’ questions are answered accurately and to the degree possible.
Members of the Frame 6 steering committee represent the electric-power, chemicals, and refining industries. They are:
* Co-chair Jeff Gillis, ExxonMobil Chemical Co.
* Co-chair Sam Moots, Colorado Energy.
* Robert Gides, Chevron Global Power.
* Geoffrey Kret, Total Petrochemicals USA.
* John Vermillion, Capital Power Corp.
* Brian Walker, Foster Wheeler Martinez Inc.
* Zahi Youwakim, Huntsman Corp.
Walker, Gides, Moots, Youwakim, Gillis; Kret and Vermillion camera shy
Topics on the minds of the Frame 6 users during the discussion sessions included the following:
Fiberoptic flame detector. Some users have reported that liquid-cooled flame scanners can cause nuisance trips because the sight tube turns into a condenser during startup and water droplets can form on the sensor lens and refract UV radiation. There also are concerns of potential damage to the turbine from leaking coolant. Conversion to a fiberoptic flame scanner eliminates such concerns and is relatively easy the group was told by one user.
Exhaust systems take a beating in service. Years of demanding duty, frequent cycling in some applications, and/or overheating can contribute to a level of degradation that can be addressed in practical terms only by replacement. A user presented a positive overview of an exhaust plenum replacement by a third-party services provider. Article from the 2010 Outage Handbook offers guidance for others evaluating similar action.
Safety discussion was robust as it is at most user-group meetings these days. Lockout/tagout, fall protection, and installation of permanent scaffolding got considerable attention. Best practices on these subjects can be found in the 1Q issue of every CCJ; access www.ccj-online.com and skim through the back issues.
One takeaway was a pitfall of having too many lockboxes. At one plant with individual lockboxes for the gas turbine and heat-recovery steam generator, personnel identified a safety issue when GT tests were scheduled while maintenance was ongoing in the HRSG. Fix was to consolidate lockboxes.
Black-start arrangements were a lively discussion topic. Attendees generally agreed there were many variations in circuitry among similar plants. Point was raised that the OEM has no standard black-start package and it often is left to the EPC contractor. Suggestion was to review this system if you change plants to make sure you know how it works; make changes as necessary to assure operational safety.
Confined space entry was a hot topic. In the past, one attendee said, if your head was out of the confined space your whole body was considered out; today, if any body part is in the confined space your whole body is considered in the confined space. Some plants do not require a permit for confined-space entry and this was said to be fine with OSHA.
A good exchange ensued on the idea of package entry without turning off the CO2 system. A couple of attendees said LOTO was not required at their plants and the person on rounds enters without OBA protection. Another user said if you open the compartment door at his plant, which has a CO2 system, the turbine trips. Most attendees thought this harsh.
There was general agreement that the inlet plenum is a confined space. Consensus view to assure safety was lock out of the IGV before entering the inlet plenum. Pulling of actuator pins might be the best way to do this.
Compressor efficiency was another timeless discussion topic. Protruding shims pulled out, cut off, pinned were part of the initial exchange as was take-up of IGV gear backlash. Lifetime of compressor blades then was debated. Several users in the room had more than 150,000 hours on their blades, none over 200,000. Others suggested that just because the blades were in one piece didn’t mean they shouldn’t be replaced.
Measuring of compressor efficiency was suggested. A couple of users contended that first-stage blades with long service hours tend to get flat spots and this costs you power. Replacing the row in such instances may squeeze another megawatt from a Frame 6.
On the subject of compressor washing, an attendee said his plant switched from one 30-min wash daily to two 15-min washes and that was beneficial. Someone else mentioned the OEM saying that 90% of the benefit of online washing was realized in the first 15 minutes.
