There’s no limit to what you can learn at a user-group exhibition, and it’s not just about equipment. Here are a few tidbits picked up by the editors in Greenville:

Sign up NOW for tomorrow’s webinar on brush-holder and slip-ring problems

The Cutsforth people were talking up their free 30-min educational webinar, Thursday, July 12, at 3 pm Eastern time, on the root causes and solutions of common brush-holder and slip-ring problems that can put your generator at risk for a catastrophic failure. Participants will learn how to identify common problems and what to do to prevent them. All gas and steam turbine owner/operators qualify for a complimentary registration. Access www.cutsforth.com now to register.

Precision Iceblast on network TV

Keith Boye, VP of Wisconsin-based Precision Iceblast Corp, was promoting PIC’s upcoming appearance on the World’s Greatest TV show July 23 and 30 (see schedule below), which airs on the ION cable network later this month; it is accessible as well via DirecTV and Dish channels identified in the schedule. Eight companies are profiled in each half-hour segment of the show, which has been running for six years.

World’s Greatest Production Manager Josh Kessler told the editors that PIC was selected for the interesting work it does and for its “stellar reputation” among customers in the industries served. He said development teams consisting of producers, writers, and researchers continually scour the nation’s myriad industries for interesting products, services, etc. Suppliers selected for further review are investigated and evaluated. The leading candidates then are interviewed and a company is selected for inclusion in the show. A script is prepared and film crew typically spends a day in the field shooting company segment. The profile demonstrating how HRSG tube bundles are cleaned was filmed at an F-class 2 x 1 combined cycle in March 2012.

If you’ve never watched an HRSG be cleaned with dry ice, here’s an opportunity. Tune into World’s Greatest at one of the times below.

Yet another use for dry ice: Painting prep

Donaldson Company Inc’s Barry Link, a familiar face at user group meetings, told the editors that his company and Precision Iceblast Corp (PIC) had teamed up to offer upgrade and rehabilitation services for gas-turbine air inlet systems. Deterioration of metal surfaces is relatively common in air inlet houses because painted carbon steel is the material of choice for filter and evap-cooler structural members among parsimonious owners, and the environment typically is high-moisture. Rusting metal contributes to wear and tear of compressor airfoils because oxide continually flakes off and flies downstream at high velocity into the unit.

Theoretically, just about any maintenance person can wire-brush away rust spots and hit them with paint. But that won’t cut it in the air inlet house. Rusting is virtually sure to continue under the glob of paint and the next flake that comes off will be bigger, heavier, and do more compressor damage.

Donaldson always offered customers painting services where required, typically using sandblasting equipment to prep surfaces after removing filters and evap-media fill. Cleanup always was a painful part of the job, recalled Link. Every bit of grit and all the paint it removed had to be swept/vacuumed up and removed prior to painting. No one wanted that material being swept downstream into the compressor. PIC had an idea: It could remove rust, loose paint, etc, with high-pressure CO2 blasting leaving only rust and paint chips for the clean-up crew. Plus, the company had crews trained in powerplant practices from its work cleaning HRSG heat-transfer surfaces, as well as the scaffolding to access all surfaces requiring treatment. Finally, PIC had coatings experience from work in other industries (photos).

Before

After

Here’s the way a typical evap-cooler restoration project works for an F-class installation: Donaldson crew removes the evap media on the first day; PIC does the scaffold erection, installation of curtains downstream of the cooler, CO2 blast, coating (12 mils of an epoxy designed for marine environments), curtain removal/scaffold breakdown, and cleanup over the next four days; Donaldson crew reinstalls media (previous or new) in two days.

The editors called a couple of customers whom they knew from other user-group meetings. One plant manager with four 7EAs and one 7FA—all peakers—said he had a real corrosion problem with his big machine and hired Donaldson to correct it. Coating lasted less than a year. Surface preparation by sandblasting inadequate he said. Next attempt was by a Donaldson/PIC team. Seems to have worked well the PM said, “More than a year later, the evap cooler still looks OK.” Evap coolers on two of the 7EAs were overhauled the same way last fall; success. Coolers on the remaining two units will be restored this fall.

The second user contacted said he hired Donaldson to replace filters (plant gets about five years on a set of filters) and evap media (nominal 10-year life) and to restore the evap-cooler framework. He knew PIC from previous HRSG work and embraced the partnership for his project. Final assessment: The two teams worked seamlessly, quickly, and efficiently. He did a back-of-the-envelope calculation that suggested the plant could repaint the evap cooler as often as every two years and still be less expensive than retrofit with a stainless-steel frame. Cooler condition is checked annually. This user took the opportunity to make a small modification to the evap cooler as suggested by Donaldson: Installation of drains at the ends of the water distribution header to eliminate packing of debris and promote better distribution of water across the media. Better performance resulted. 

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