Synergy between fired boilers, HRSGs increases value proposition of AHUG, now ABHUG

The experiences shared at the Australasian HRSG Users Group (AHUG) annual meeting have been chronicled for the last decade by CCJ ONsite and in the print edition of the Combined Cycle Journal. Beginning here, and going forward, you’ll also benefit from the lessons learned/best practices of fired-boiler owner/operators facing technical and operational issues closely related to those in HRSGs.

The first annual meeting of the Australasian Boiler & HRSG Users Group (ABHUG), chaired by Barry Dooley of Structural Integrity Associates Inc, attracted 75 participants from Australia, Japan, New Zealand, Thailand, UK, and US to the Brisbane Convention & Exhibition Centre, Oct 30-Nov 1, 2019. About half of the participants were users. The agenda included 21 technical presentations and a welding workshop that brought together multiple experts to present on the latest standards, welding of service-exposed materials, ligament cracking in superheater headers, cold repair of Grade 91 material, etc.

The steering committee voted to expand the attendee base because many of the failure/damage mechanisms occurring in HRSGs are similar to those found in conventional boilers, and that other equipment in combined-cycle plants have many of the same issues as those in fossil stations. Dooley told the editors that ABHUG will continue to concentrate on HRSG aspects but will add the technical areas common to fossil and HRSG plants—such as tube failures, steam turbines, high-energy piping, valves, etc.

The chairman characterized the inaugural ABHUG meeting as a highly interactive forum for the presentation of new information and technology related to HRSGs and boilers, case studies of plant issues and solutions, and open discussions among users, equipment suppliers, and industry consultants.

ABHUG is supported by the International Association for the Properties of Water and Steam together with the local national committees of IAPWS in Australia and New Zealand. It is held in association with the European HRSG Forum (EHF) and the US-based HRSG Forum with Bob Anderson. Two gold sponsors—Bang&Clean Technologies AG and HRL Technology Group—and seven exhibitors—ALS, Duff & Macintosh and Sentry, Flowtech Controls, Quest Integrity, Mettler Toledo, Optimum Control, and Swan Analytical—provided financial support (see end notes).

Highlights

• • International updates on cycle chemistry, instrumentation, and flow-accelerated corrosion (FAC), plus a review of the recent IAPWS Technical Guidance Documents (TGD) in those areas—including the following:
    • • Applications of Film-Forming Substances (TGD11-19).
      • Air In-leakage in Steam-Water Cycles (TGD9-18).
      • Chemistry Management in Generator Cooling Water during Operation and Shutdown (TGD10-19).

• • International updates on HRSG thermal transients associated with attemperators, condensate return and superheater/reheater drain management, and bypass operation.
  • Two fossil-plant presentations on pitting were of practical value to operators of HRSGs. This mechanism is unique to reheaters and discussion focused on how it occurs when layup procedures are not in keeping with best industry practices. While the topic has been discussed at AHUG meetings over the years, these presentations illustrated how severe the damage can be.

Both presentations were followed by discussions on the use of dehumidified air (DHA) for reheaters and steam turbines. Typically, however, DHA capability is added after the damage has occurred, not as a proactive solution beforehand.

• • A practical presentation on hexavalent chromium contamination of high-chrome materials in gas turbines, HRSGs, steam turbines (casing bolts), and steam piping was made by David Addison of Thermal Chemistry Ltd. He covered how and where hex chrome forms, the health risks it poses, PPE requirements, best work practices, proper disposal, etc. An article based on Addison’s work will be published in the first quarter of 2020.

• • A new inspection tool on developing a digital twin of pressure vessels and other plant components using state-of-the-art imaging and image-capture technology was described. Chairman Dooley said an interesting application of the technology might be its use in the upper ducts of an air-cooled condenser (ACC) to view, without entry into the upper ducts (streets), the tube entries and any associated FAC. He should know: Dooley is a member of the ACC Users Group steering committee and respected for his knowledge of ACC damage mechanisms.

• • Operators representing four generating stations equipped with HRSGs shared their experiences in the form of “a year in the life” of their respective plants. This format was well-received by attendees.

• • The question/answer periods included impromptu discussion of the oxidation limits for steels used in superheaters and reheaters. Dooley announced that a new index on oxide growth and exfoliation (OGE) is in preparation. It will discuss the formation of steam-side oxide, how the characteristics of oxide exfoliation vary from one material to another, and the various types of damage caused by different exfoliated oxides. OGE piqued the interest of attendees at the 2019 meeting of the HRSG Forum with Bob Anderson as noted in the meeting report for that event.

• • Experiences with pressure-wave cleaning of fireside/gas-side surfaces in fossil boilers/HRSGs were shared at the same forum perhaps for the first time. Pressure-wave cleaning of HRSGs was a “hot” topic at the 2019 meeting of the HRSG Forum with Bob Anderson as mentioned in the meeting report for that event.

End notes: Sponsor, exhibitor briefs

The sponsors and exhibitors active in ABHUG may be unfamiliar to readers in the Western Hemisphere. What follows are summaries of their activities:

ALS is one of Australia’s leading providers of asset reliability and integrity services geared to help power producers maximize production, extend asset life, and assure top operational performance.

Bang&Clean Technologies AG specializes in cleaning boilers and HRSGs by way of pressure waves created by closed and controlled gas explosions. The Swiss company’s patented system reportedly has been used in more than 20,000 cleanings since 2001.

Duff & Macintosh has specialized in the area of sample conditioning for the last 50 years. It is the exclusive agent in Australia Pacific for Sentry Equipment Corp.

Flotech Controls provides valve solutions, specializing in severe-service isolation and control applications.

HRL Technology Group focuses on laboratory testing, asset integrity, materials engineering, power and combustion performance engineering, and process and energy efficiency engineering.

Quest Integrity is active in the development and delivery of asset integrity and reliability management services.

Mettler Toledo Process Analytics specializes in inline analytical process solutions. Its Thornton unit provides state-of-the-art technology in conductivity, sodium, silica, chloride/sulfate, pH, ORP, ozone, dissolved oxygen, and TOC measurement.

Optimum Control Co represents a range of valve and actuator manufacturers and has a facility in Sydney to repair those components.

Swan Analytical Instruments offers a range of analyzers for pure, ultra-pure, and cooling-water applications—including pH, conductivity ORP, dissolved oxygen, silica, sodium, phosphate, chlorine, chlorine dioxide, bromine, iodine, ozone, and turbidity.

2020 meeting

ABHUG returns to the Brisbane Convention & Exhibition Center next year, in early December. Follow the organization’s website for announcements.