Author: anderthalbAdmin

Comparison of Two Corrosion Product Sampling Methods at Eraring Power Station

Mark Wyburn

Cycle chemical conditions have been modified several times over the last 20 plus years at Eraring Power Station (EPS) in Australia. The mixed metallurgy of the condensate system had proved difficult to manage with respect to minimising flow-accelerated corrosion (FAC) and copper transportation.

A project to convert all units from all-volatile treatment under reducing conditions (AVT(R)) to all-volatile treatment under oxidising conditions (AVT(O)) has been underway since 2016. Units 1, 2 and 4 have now had their 35-year-old brass-tubed low-pressure (LP) heaters replaced with stainless-steel-tubed heat exchangers, and Unit 3 will be converted in late 2019.
After each AVT(O) conversion, intensive corrosion product sampling and analysis has been undertaken over several months to measure the success of the project in reducing iron transportation. This has involved simultaneously using integrated sampling and an on-line voltammetric analyser, which was previously trialled in 2015. This analysis has revealed some interesting trends during the chemistry change.

This paper compares the results from integrated sampling and the voltammetric analyser and discusses the relative merits of each process under the constraints of major power plant operations in a competitive market.

PPCHEM^® 2019, 21(5), 270–285

Knowledge Transfer and Succession Planning for Power Plant Chemistry

Bertil C. Valenkamph, Paul E. Schrock, Brian S. Snyder, and K. Anthony Selby

Electric utilities are faced with a shortage of skilled personnel in the coming years due to normal retirements, early retirements, and plant closings. This is true in chemistry departments as well as other departments.

There are many aspects to succession planning to successfully fill the upcoming vacancies. For chemistry departments one important tool is to develop comprehensive written plans for chemical control of the systems impacted by chemistry. These plans can be termed control plans or strategic plans. The chemistry plans should be developed for several individual plant systems, including boiler cycle chemistry, open cooling water, closed cooling water, makeup treatment systems, glycol systems, and wastewater treatment systems, among others.

Another very important tool is the comprehensive chemistry data acquisition system – a collection of supervisory control and data acquisition (SCADA) nodes at each generating station, accompanied by a combined web-based management system overview. These systems are vital in monitoring all the process chemistry systems explained in the aforementioned control/strategic plans.

This paper describes the development and content of control/strategic plans for chemistry control in these various systems as well as several other succession planning items.

PPCHEM^® 2019, 21(5), 292–297

IAPWS TGD11-19: Application of Film Forming Substances in Industrial Steam Generators

The International Association for the Properties of Water and Steam

This Technical Guidance Document addresses the use of film forming substances in the water/steam cycles of industrial steam generating plants.

In order to control corrosion throughout the water/steam circuits of industrial steam generating plants, it is essential for the operator of the plant to choose and optimize a chemical treatment scheme that is customized to that plant. IAPWS has provided guidance on the use of volatile treatments as well as for phosphate and caustic treatments; this document addresses the use and application for the range of chemicals referred to as film forming substances (FFS). As well as providing background information on FFS, the document includes guidance in Section 8 for determining if a FFS should be applied, the tests required before application, the locations for the addition, the optimum dosage level, and tests to determine the benefits of applying FFS. It is emphasized that this is an IAPWS guidance document and that, depending on local plant requirements, the application of FFS will need to be customized (Section 9) for each industrial plant depending on the actual conditions of operation, the equipment and materials installed, the condenser cooling media, and applicable regulations.

PPCHEM^® 2019, 21(5), 302–359

An Interlaboratory Test of Analysis Methods for Corrosion Products

Karsten Thomsen and Maja Skou Jensen

This report describes the outcome of an interlaboratory comparison of analysis methods for iron among a group of laboratories in the power and heat industry. The samples sent out to the laboratories were real samples of feedwater and district heating water that had an inherent inhomogeneity due to the particulate nature of the corrosion products. The analysis methods compared were the standard methods based on spectrophotometry and inductively coupled plasma spectroscopy as well as analysis of filtered material on a 0.45 μm membrane filter. The filtered material from a 1 L sample was digested and dissolved to a 50 mL final sample volume, which gave a concentration factor of 20, enhancing the sensitivity of the method relative to the others. The purpose of the interlaboratory comparison was twofold: to qualify the filter method to be recommended for corrosion product analysis by the International Association for the Properties of Water and Steam in a Technical Guidance Document, and to give the laboratories an opportunity to test their methods on realistic samples against a group of other professional laboratories. For accredited laboratories, proficiency testing like this is a well-known and prescribed means of quality control and often supplements the internal quality control nicely.

Although measures had been taken to minimize the heterogeneity of the samples, the district heating samples turned out to be not even close to homogeneous. By assuming a log-normal distribution and independent results of the double determinations from each laboratory, the inhomogeneity of the samples could be handled, and the performance of the laboratories compared. The comparison shows that the reproducibility of the filter method matches the reference methods, and that both feedwater and district heating water samples fit nicely to the log-normal distribution. The results indicate that the filter method is reproducible when transferred from one laboratory to another.

PowerPlant Chemistry 2019, 21(4), 218–229

Thirty Years of Experience with Film-Forming Amines at a Norwegian Fertilizer Production Site

Roy van Lier, André de Smet, Lene-Marie Olsen, Matej Halasa, and Trond Arve Fjærem

In Glomfjord, Norway, above the Arctic Circle, Yara produces some 400 000 t (100 % equivalent) per year of nitric acid in two older units. All of the acid is used in downstream plants on site to produce a range of fertilizer grades.

The Glomfjord site has been of great importance both to the pioneering of ammonia and nitric acid synthesis technology and to the history of Norsk Hydro, which eventually divested its fertilizer activities as Yara International. It is also a location with some of the longest operational experience with film-forming amines for industrial steam system treatment, certainly in relation to nitric acid production.

The present paper first provides background information on the Glomfjord site. Steam generation in nitric acid plants in general is then succinctly explained. Yara’s operational experience is subsequently elaborated in the context of the specificities of the Glomfjord application, and of filming amine and water chemistry in the Nordic countries. This includes analysis of a possibly unique case of fouling and damage that illustrates the importance of adequate boiler feedwater quality, regardless of the chemical treatment program in place.

PowerPlant Chemistry 2019, 21(4), 232–241

Critical Chemical Issues during Pre-commissioning

Andrés Rodríguez Pérez

Most cases of severe corrosion and consequent failure in the commercial operation of water-steam cycle and boiler systems are initiated during the first stages of a project, frequently because of a lack of preservation, an absence of regular inspections, inadequate water quality for pressure tests and a lack of understanding of corrosion processes by many of the parties involved.

Selecting an appropriate pre-commissioning program control will mitigate the risk of corrosion during the progression of the project, and subsequently, minimize potential failures upon commissioning.

Putting together an effective pre-commissioning strategy requires a great deal of coordination among different departments, the integration of practical lessons learned and great common effort throughout the project. Even engineers involved in the first stages need to retain responsibility for keeping a long-term vision for the success of the final results.

PowerPlant Chemistry 2019, 21(4), 242–249