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Human Performance & Cycle Chemistry – The Missing Link? Part 2

Brad Burns and Doug Hubbard

On most units assessed by the Electric Power Research Institute (EPRI) across the world, cycle chemistry is well controlled and good results are obtained 99.9 % of the time. Fossil and combined cycle power plants on a global scale continue to boast higher cycle chemistry benchmarking scores, installation of new instrumentation and alarming, and management support for cycle chemistry. The exception, however, continues to be major cycle chemistry excursion events that happen infrequently, yet with great consequences.

Often, when an unmitigated major cycle chemistry upset event occurs, root cause investigations pin the event on inadequate skills or knowledge (of individuals). It is therefore believed that additional training and/or disciplinary corrective action solves the root cause of the event and will prevent poor operator response to out-of-spec chemistry from recurring.

But does this approach produce the desired results? This article continues part 1, which was published in the January/February 2021 edition of this publication. Human performance improvement was described as the potential “missing link” to achieve true cycle chemistry improvement. This article builds upon the previous one by providing practical examples and suggestions for implementing improved defenses in a plant.

PPCHEM^® 2021, 23(6), 242–251

The Economic Benefits and Goals of Power Plant Chemistry

Frank Udo Leidich and Michael Rziha

Thus far, the chemist in a power plant has quite often been regarded as a necessary evil or as inevitable costs. The purpose of this paper is to explain the economic benefits of a chemist, the need to have a specialist on the operation team, the purpose and goals of the job, and the expectations of the chemist from the power plant management’s point of view.

Of course, the economic impact, the possible risks, and (monetary) damage that might arise if the job is not done as it should be are discussed here as well.

This paper concentrates on the goals and purpose of the chemist’s activities regarding the water/steam cycle and the components therein. Future papers will also deal with the chemist’s footprint on the cooling system, including the cooling water make-up system, the flue gas path, and the treatment of other systems and machines.

PPCHEM^® 2021, 23(6), 254–263

Accuracy, Trueness and Precision of Measurement Methods and Results

Michael Rziha

The present paper is an updated revision of a paper presented 22 years ago at the joint European NUSIS-ICMG-VGB Chemistry Online Process Instrumentation Seminar in Brügge, Belgium (April 20–22, 1999).

The original paper was prepared by Dr. J. Fahlke, Grosskraftwerk Mannheim, Mannheim Central Power Station, Mannheim; W. Fichte, Consultant, Ismaning; E. V. Maughan, Tablar Messtechnik, Duisburg; H. D. Pflug, Consultant, Bergen-Enkheim; and H.-G. Seipp, ABB, Mannheim – all located in Germany.

I would like to express my sincerest thanks to Dr. J. Fahlke for providing me with the original paper and permitting me to use it as the basis for this updated version.

This paper is an attempt to facilitate understanding of the rather abstract and in part complicated definitions of the ISO 5725 by combining them with some illustrations. This approach, although it may require getting used to, will help to promote a better understanding between manufacturers, suppliers, purchasers and operators of continuously operating measuring instruments in plant cycle chemistry.

PPCHEM^® 2021, 23(6), 264–270

PPCHEM Interview with Wolfgang Rost

Tapio Werder

Wolfgang Rost joined the PPCHEM team in October 2021 as Senior Key Expert for Power Plant Technology. Tapio Werder, Editor in Chief of the PPCHEM® journal, has interviewed Wolfgang to introduce him to our readers.

PPCHEM® 2021, 23(6), 272–274

Considerations for Complex Industrial Cooling Water Monitoring and Treatment

Brad Buecker and Rajendra P. Kalakodimi

Heat exchangers are, of course, a critical component of power and heavy industrial plants. Many of these are water cooled, with the source being a cooling tower (commonly known as an open cooling system) or sometimes once-through cooling. Often, “closed” systems are also present, which are cooled by primary heat exchangers, but whose chemistry is significantly different from that of open systems. Successful chemical treatment of the wide variety of cooling systems in plants requires analysis of many factors, including the potential for corrosion, scaling, and microbiological fouling, system metallurgy, operating temperatures, and others, all of which are examined in this article. Also discussed are several significant improvements to chemical treatment programs in recent years, improvements that maintain proper heat transfer and reliability of cooling systems.

PPCHEM^® 2021, 23(5), 198–205

Weighted Salt Hours – A New Approach in Cycling Plants

Frank Udo Leidich

Thus far, the chemist in a power plant has quite often been regarded as a necessary evil or as inevitable costs. To leverage the activity of the power plant chemist and make his/her work observable and tangible in an economic sense to the management, it is proposed to introduce a new parameter, weighted salt hours, that can be used to link the key chemistry parameters with key economic performance indicators. To do this, data mining and application of statistical methods, like gauging of repeatability and reproducibility, multifactor analysis, and others analyses, are needed. Of course, such efforts can only be successful if a very high number of power plants participate and contribute to this.

PPCHEM^® 2021, 23(5), 206–210

Flexible Operations in the Energy Transformation: High-Level Impacts on Cycle Chemistry

Mike Caravaggio

Electricity generation is changing, and these changes impact all aspects of the plant. The following paper sets out some of the key changes and the high-level impacts on cycle chemistry in thermal plants. It is incumbent upon power plant chemists and chemical engineers to understand the details of how flexible operation affects their specific units, so that they can develop optimal, unit-specific solutions.

PPCHEM^® 2021, 23(5), 212–220

Assessing Corrosion in Air-Cooled Condensers at Eskom Medupi Power Station

Sabelo Khanyile, Stephanie Marais, Setsweke Phala, Zanele Dladla, and Nestor van
Eeden

Steam side surfaces of air-cooled condensers (ACC) are prone to corrosion. If the
corrosion mechanism is not understood and mitigated, it can lead to ACC tube failure(s),
and subsequent vacuum and/or condensate chemistry deterioration. Most importantly, the
total iron levels entering the condensate and feedwater systems will be much greater than
international guidance. This paper reports on the ACC corrosion assessment performed on
Unit 5 of Medupi power station. The ACC condensate chemistry is reviewed and the
“Dooley Howell ACC Corrosion Index” is reported. The latter was derived from the physical
inspections of the internal surfaces of the ACC. The inspections were conducted when the
unit was on all-volatile treatment, under oxidising conditions (AVT(O) regime), as well as
after transitioning to an oxygenated treatment (OT) regime. The benefits of transitioning
from AVT(O) to OT are also reported.

PPCHEM^® 2021, 23(5), 222–228