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Issue 02 (2024)

Impurities in Water Supplies (Natural and Reclaim) and Modern Control Methods for Industrial Plant Makeup – Part 2

Brad Buecker

Reducing industrial water consumption is a key aspect to conserving available fresh water sources. In the United States, as well as in other regions globally, project developers and design engineers for numerous power and industrial plants are opting for alternatives to fresh water for plant makeup. Effluent from municipal wastewater treatment plants, also known as “reclaim” or “grey” water, is becoming more popular as an alternative water source. The article discusses the problematic impurities found in effluent and suggests modern approaches to address these contaminants. It emphasizes the importance of careful evaluation and planning when designing industrial makeup water treatment systems, regardless of whether the water supply is fresh or an alternative source. Additional treatment might be needed to safeguard industrial plant water systems against microbiological fouling, scale formation, and corrosion.

PPCHEM® 2024, 26(2), 64–68

For Members only

Report on the PPCHEM Forum South Africa 2024

Tapio Werder

For the third time in the history of these events, the PPCHEM Forum (PPCF) series stopped over in South Africa. The PPCF South Africa 2024 in Pretoria was held under the patronage of PPCHEM AG, with financial sponsorship from SWAN Analytical Instruments, Switzerland, and Sentry Equipment Corp., USA.

The PPCF series offers valuable insights into power plant chemistry objectives and tasks, covering essential topics such as water chemistry, proper sampling techniques, corrosion science, and more. It’s designed to be understandable not just to chemical experts but also to those without a chemistry background. The various operating regimes, the relevant industry guidelines and standards, and the correct and optimum selection and application in relation to the individual plant design are discussed, as well as the necessary considerations for the operational monitoring concept.

This report summarizes the two days of the PPCHEM Forum South Africa 2024.

PPCHEM® 2024, 26(2), 70–74

For Members only

Report on the Power Cycle Instrumentation Seminar (PCIS) Germany 2024 in Goslar, Germany

Tapio Werder

For the first time in the history of these events, the Power Cycle Instrumentation Seminar (PCIS) series stopped over in Germany. The PCIS Germany 2024 in Goslar was held under the patronage of PPCHEM AG, with financial sponsorship from SWAN Analytical Instruments and REICON Wärmetechnik und Wasserchemie Leipzig GmbH.

The PCIS series provides a well-proven mixture of theoretical background information on cycle chemistry, sampling, and monitoring as well as a deeper look into analytical methods and critical issues for each parameter, concerning operation, verification, and calibration.

This report summarizes the two days of the PCIS Germany 2024.

PPCHEM® 2024, 26(2), 82–85

For Members only

New vgbe-Standard published “Feed Water, Boiler Water and Steam Quality for Power Plants/Industrial Plants”

vgbe energy e.V. hereby presents a revised version of the VGB-Standard VGB-S-010 for “Feed Water, Boiler Water and Steam Quality for Power Plants/Industrial Plants”. This revised vgbe-Standard replaces the former edition 2011.

PPCHEM® 2024, 26(2), 92

IAPWS Film Forming Substances (FFS) Conference, FFS2024 Highlights and Press Release

The seventh IAPWS FFS International Conference was held on the 26th – 28th March 2024 in Prato, Italy chaired by Barry Dooley of Structural Integrity Associates, UK and David Addison of Thermal Chemistry, New Zealand. The FFS conferences are unique on a narrow topic in cycle chemistry control of power plants and steam generating facilities. In 2024 the conference attracted 50 participants from 16 countries from all over the world which included 10 plant operators / users and representatives from 12 FFS chemical suppliers.

PPCHEM® 2024, 26(2), 96–98

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Issue 01 (2024)

Steam Turbine Deposits – How They Occur, Their Effects and How They Can Be Eliminated

Frank Udo Leidich

During operation, impurities can enter the water-steam cycle (WSC) with the make-up water, through leaks or with the process condensate return and cause corrosion and deposits. Deposits can form at any point in the WSC, depending on the composition and local conditions (pressure, temperature, flow conditions). Deposits are formed from dissolved and suspended substances that are transported from the point of formation to the point of deposition in the WSC with the water or steam flow. The deposits formed on the turbine blades not only disrupt the flow around the blades, they also increase the pressure loss between the turbine inlet and outlet and thus reduce the efficiency of the overall process.

Three methods for removing turbine deposits have proven to be particularly effective, whereby each of the methods mentioned has specific advantages and disadvantages which will be discussed in this article.

PPCHEM® 2024, 26(1), 4–13

For Members only

Foam Cleaning of Gas Turbine Compressors – A Fast and Efficient Method to Reestablish Performance and Efficiency

Frank Udo Leidich

Especially in industrial environments, gas turbines (GTs) suffer from performance losses and efficiency losses due to compressor fouling. Compressor fouling is caused by soot, dust, salt spray and other airborne contaminants that are drawn into the compressor with the combustion air and are not fully retained by the air intake filters. Another cause of deposits on the compressor blades is the water used for fogging or high fogging if the water quality does not meet the purity requirements according to the original equipment manufacturer (OEM) specifications.

Depending on the pollutant load in the combustion air, GT compressors must be cleaned regularly to remove all deposits and restore the efficiency of the compressor. There are various methods for cleaning. These methods are discussed here.

PPCHEM® 2024, 26(1), 18–22

For Members only

A Brief Introduction to the International Association for the Properties of Water and Steam

Tapio Werder

This paper aims to offer a concise introduction to the International Association for the Properties of Water and Steam (IAPWS) in response to requests of PPCHEM readers. It briefly discusses the advancements in steam property research in the early 20th century and the establishment of international collaboration through the first international steam table conference held in London in 1929. Due to the limited space available, the article presents only a selection of the most important events and facts. It further outlines the organization’s activities, which encompass annual meetings, international conferences, working groups, and the creation of formulations, guidelines, releases, and certified research requirements.

PPCHEM® 2024, 26(1), 30–34

For Members only

2023’s Scientific and Technical Contributions

PPCHEM® 2024, 26(1), 46–53

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Issue 06 (2023)

Sodium Analyzers and Film-Forming Substances: Working Together?

Eric M. Etter and Harold Stansfield

The increasing application of film-forming substances (FFS) in power generation and process steam applications as a corrosion mitigation strategy has raised concerns regarding their impact on plant systems, particularly valves, piping, and instrumentation. This study focuses on the adverse effects reported by users of film-forming amine (FFA) products, including loss of instrumentation sensitivity, premature electrode failure, sensor fouling, and overall accuracy and reliability issues.

Experiments aimed at replicating field conditions have revealed rapid sensor fouling occurring well before standard maintenance cycles for electrode cleaning and replacement. The observed accelerated fouling necessitates frequent mechanical cleaning, posing risks of electrode damage, increased downtime, and additional labor for maintenance. Because the fouling does not result in calibration failures, this creates a situation where the analyzer appears to be functioning normally, but is no longer capable of responding to adverse events such as a condenser leak. These highly dampened responses will follow trends over time but are incapable of rapidly reflecting transient spikes or changes in values.

PPCHEM® 2023, 25(6), 296–299

For Members only

Cooling Tower Operating and Water Treatment Fundamentals – Part 2

Brad Buecker

Cooling water systems are an integral component of many power plants and industrial facilities of all types. Performance degradation from microbiological fouling, scale formation, and corrosion can seriously impact plant operation and revenue. Severe cases may force unit process or plant shutdowns. The remainder of this series examines the most problematic fouling, scaling, and corrosion mechanisms, and it outlines modern control methods for all of them. This installment focuses on microbiological fouling, with much of the discussion extracted from Reference 1.

PPCHEM® 2023, 25(6), 310–318

For Members only

Why Do Sample Coolers Fail?

Aditya Sanjay Kanetkar

In steam and water analysis systems (SWAS), the sample cooler is one of the most important components. The main function of the sample cooler is to reduce the temperature of high-temperature samples from elevated temperatures to the temperature required for analyser sensors. In the case of steam sampling, the steam samples are not just cooled, but are condensed to water (phase change).

PPCHEM® 2023, 25(6), 322–325

For Members only

Additives from Natural Resources – The Way to the Future?!

Wolfgang Hater

Additives from natural resources have been known since the end of the 19th century and have had a renaissance in recent years due to the demand to replace mineral-oil-based chemistry with materials from nature. They are considered to be green and sustainable. In spite of their positive image and a huge number of research papers, hardly any new compounds from natural materials have successfully found their way onto the market.

The assumption that natural equals harmless, green, or sustainable is quite common but does not always hold. While the criteria for green and sustainable are not well defined, the European Community has developed a standardized risk-based approach for the evaluation of whether a chemical can be safely applied.

This paper describes the major advantages and drawbacks related to natural material or biobased material. On the one hand, the production process is generally more simple and raw materials are cheap, especially if waste/recycled materials or residues are processed. On the other hand, a serious obstacle is the high variability of their chemical composition as well as the presence of components with no function.

Selected examples of studies and the application of additives from natural resources for water treatment are briefly discussed which show the potential but also the roadblocks for market success. It can be expected that they will play an increasing role in the future. Legislation will also be a strong influencing factor.

PPCHEM® 2023, 25(6), 330–337

For Members only

Review vgbe Chemistry Conference 2023 October 24 to 26, 2023 in Ingolstadt

Around 170 participants attended the 59th vgbe Chemistry Conference from October 24 to 26, 2023. The wide-ranging lecture programme was once again rounded off by an accompanying trade exhibition with 20 exhibitors who presented their products and services relating to power plant chemistry.

The vgbe conference team would like to thank all speakers, exhibitors and sponsors as well as the interested participants for their support and looks forward to the next vgbe Chemistry Conference, which will take place in Potsdam from October 22 to 24, 2024.

PPCHEM® 2023, 25(6), 338–339

ABHUG 2023 Highlights

The annual meeting of ABHUG held on the 14th–16th November 2023 in Brisbane, Australia was chaired by Barry Dooley of Structural Integrity Associates, UK and Bob Anderson, Competitive Power Resources, USA. This ABHUG conference included conventional fossil plant technology and issues closely related to those in HRSGs. ABHUG2023 attracted 100 participants from Australia, New Caledonia, New Zealand, Singapore, Switzerland, UK and USA. About 55 % of the participants were Users.

The next meeting of ABHUG will be in Brisbane around early December 2024.

PPCHEM® 2023, 25(6), 340–341

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Issue 05 (2023)

A Specialty Ion Exchange Resin for Deoxygenation Treatment of
Boiler Makeup Water

Zhendong Liu, Amy Peddie, and Juan Carlos Pinilla

Oxygen level control can be very important in the cycle chemistry of power plants. Sometimes a higher oxygen level is desired for all-ferrous materials due to its creation of the more corrosion-resistant ferric oxide hydrate layer in the natural magnetite. This is practiced as either all-volatile treatment under oxidizing conditions (AVT(O)), or oxygenated treatment (OT). However, for some alloy materials (e.g., copper alloys and nickel alloys) used in the steam generation/recirculation systems, a reducing environment and very low oxygen levels are favored to avoid corrosion. This paper reports on a specialty ion exchange resin and its use in treating the makeup water for a pressurized water reactor (PWR) nuclear power plant. The resin is coated with a precious metal as catalyst for the oxygen-hydrogen reaction to generate water. It requires minimum maintenance (only annual backwashes), and has fast reaction kinetics, a small footprint, and a long operating life (> 20 years). The case study shows the resin can achieve < 10 μg ⋅ L–1 oxygen consistently from a makeup water with 1–10 mg ⋅ L–1 oxygen at a 189–1 514 L ⋅ min–1 flow rate. The catalyst doping, reaction mechanism, and some operational details are discussed.

PPCHEM® 2023, 25(5), 240–244

For Members only

Press Release – IAPWS Annual Meeting 2023

Between September 3rd – 8th, 2023, 62 scientists, engineers and guests representing 20 countries converged in Turin, Italy at the Star Hotel Majestic for the annual meetings of the IAPWS Executive Committee and Working Groups. This continues a series of meetings that began in 1929 in London, UK with the purpose to connect scientists and researchers with the industry operators, engineers and managers who use their work. Collaboration and engagement across these varied groups provides guidance to the researchers on topical problems within industry and provides the engineers with the latest research results for direct application in their facilities.

The main meetings included discussions around power cycle chemistry, high temperature aqueous technologies applicable to steam cycles and hydrogen generation, oceanography and global climate modelling, geothermal steam, electrode boilers, power cycles with CO2 capture and storage systems and combined heat and power systems.

PPCHEM® 2023, 25(5), 250–251

The Role of Organics in Relation to Corrosion in Steam-Water Systems

Yu Xue, Karlien Dejaeger, Ben Bischoff Tulleken, Duygu Disci, Peter Janssen, Andrea M.Brunner, David Moed, Wolfgang Hater, Emile R. Cornelissen, and Marjolein Vanoppen

A sampling campaign was conducted in a film-forming amine product (FFAP) treated highpressure steam-water system of an ammonia producing plant to optimize the cycle chemistry. Cycle chemistry guidelines were assessed to be applicable with modifications fitting the local situation according to the pH and conductivity. Methanol, a main organic compound originating from the production process, entered the steam-water system with the process condensate and was tested possible to degrade. Furthermore, organic compounds from cation exchange resin were found in blowdown streams, suspected to originate from resin carryover. No operational and corrosion issues were observed.

Lab-scale first condensate experiments confirmed that a lower pH was present in the first condensate compared with the bulk steam, however, it was still partially buffered by ammonia. Via corrosion tests it was observed that oleyl propylenediamine (OLDA), in addition to ammonia, formed a smoother and more uniform magnetite layer. Moreover, magnetite layers formed under OLDA added to ammonia were more resistant against acidic conditions (pertinent to condensate return systems) than layers formed under the ammonia only chemistry and blank chemistry (without a chemical additive), with less reduction of the magnetite layer thickness.

These studies in combination with the plant experiences confirm that the steam-water system can be safely run with the selected FFAP treatment concept even with organics from the production process.

PPCHEM® 2023, 25(5), 256–275

For Members only
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Issue 04 (2023)

Cooling Tower Operating and Water Treatment Fundamentals – Part 1

Brad Buecker and Rich Aull

Process cooling is an important operational factor in many industrial plants and commercial office buildings around the world. Most of these plants use cooling towers for primary cooling. A large facility may have dozens of towers scattered throughout the premises. Often, plant personnel are focused on process engineering and chemistry, potentially neglecting cooling systems until a serious disruption occurs that threatens plant production or, worse, jeopardizes employee safety.

This article forms the basis of a short series of articles dealing with the chemistry of cooling systems. In this first part of the series, we examine the fundamentals of heat transfer in the cooling tower and the methods that have been developed to improve heat exchange in the tower. Subsequent parts discuss modern water treatment methods to ensure reliable performance.

PPCHEM® 2023, 25(4), 190–198

For Members only

Cooling Tower Disinfection Switch to Chlorine Dioxide Reduces Boiler Chloride Cycling: Why and How? – Part 2

Emmanuel K. Quagraine, Trever McNabb, Taneal Weiss, Gillian Bailey, Nikki Wirtz, Khrystyna Vasylkiv, and Daniel Schorr

This is the second half of a two-part article discussing the abatement of selective boiler chloride cycling (SBCC) upon switching the recirculating cooling water (RCW) biocide from NaOCl to ClO2. The use of ClO2 treatment significantly reduces SBCC, with only sporadic spikes observed to a much lower extent. These spikes are found to be related to the plant’s operation, coinciding with sudden load drops and increased air injector flows. It is suggested that these spikes may be caused by small ClO2(g) residuals condensing at the air injector condenser and entering the feedwater, eventually reducing to chloride ions (Cl–) in the water/steam cycle. Unlike chlorination, ClO2 treatment prevents the formation and persistence of volatile chlorine compounds (VCCs), including ClO2(g). The residual ClO2 in the RCW that is responsible for the highest observed daily boiler chloride rise during ClO2 treatment is estimated to be 4.05–9.74 ⋅ 10–5 mg ⋅ L–1. However, this concentration range represents only 0.02–0.23 % of the highest to the least measured residual concentrations, confirming the previous assertions that maintenance of substantial residual ClO2 in RCW, especially when using treated municipal wastewater as make-up, is unlikely. Overall, the operational data supports the switch from NaOCl to ClO2 as an effective method for reducing SBCC in the water/steam cycle, with ClO2 treatment showing superior performance and minimal VCC formation compared to NaOCl.

PPCHEM® 2023, 25(4), 202–210

For Members only

Chemistry Requirements of the Steam Turbine

Frank Udo Leidich

Safe and trouble-free operation of a steam turbine requires monitoring and control of the operating medium “steam.” In particular, it is necessary to prevent impurities in steam from causing corrosion attacks on turbine components, which, depending on the form of corrosion, can lead to sudden, unpredictable component failure. This PPCHEM 101 describes typical damage and failures that will eventually occur if the quality of the water and steam does not meet the requirements as stated in the operation manual of the steam turbine manufacturer and/or global standards and technical guidance documents as released by, for example, the International Association for the Properties of Water and Steam (IAPWS).

PPCHEM® 2023, 25(4), 220–226

For Members only

ERRATA

Nobody is perfect and everybody makes mistakes sometimes. We apologize to the authors and to our readers for the mistakes in the article:

Effect of Zinc Water Chemistry on the Corrosion and Stress Corrosion Cracking Behavior of Structural Materials in Light Water Reactors – A Review

Xianglong Guo, Kai Chen, Hans-Peter Seifert, and Stefan Ritter

PPCHEM® 2023, 25(3), 124–147

The corrected version of the paper (a PDF file)
is available to all readers here.
The details of the errata can be found in the pdf:
Posted on

Issue 03 (2023)

Effect of Zinc Water Chemistry on the Corrosion and Stress Corrosion Cracking Behavior of Structural Materials in Light Water Reactors – A Review

Xianglong Guo, Kai Chen, Hans-Peter Seifert, and Stefan Ritter

Zinc (Zn) injection into light water reactor coolants has attracted increasing attention since the reporting of its positive effects on reducing the susceptibility to stress corrosion cracking (SCC) of steam generator tubes made of Alloy 600. Revealing the corrosion and SCC mechanisms of structural materials exposed to Zn water chemistry (ZWC) has gained importance in quantifying potential benefits for the safe long-term operation of nuclear reactors. This paper reviews the open literature on the current understanding of ZWC effects on the (uniform) corrosion and SCC behavior of structural materials used in western light water reactor plants. Some research with promising results has been conducted, but more detailed and systematic work is still needed to draw meaningful conclusions on the SCC mitigation capabilities of the ZWC.

PPCHEM® 2023, 25(3), 124–147

For Members only

Impurities in Water Supplies (Natural and Reclaim) and Modern Control Methods for Industrial Plant Makeup – Part 1

Brad Buecker

Makeup water for power and industrial plants typically contains numerous impurities. Many come from natural processes, while others, often in slight but at times potentially troublesome amounts, come from human activities. The contaminants can cause fouling, scaling, and other problems in cooling, service, and high-purity makeup systems unless treatment methods are employed to reduce impurity concentrations. This series examines how impurities enter water supplies, and it provides an overview of modern treatment methods.

PPCHEM® 2023, 25(3), 148–154

For Members only

Cooling Tower Disinfection Switch to Chlorine Dioxide Reduces Boiler Chloride Cycling: Why and How? – Part 1

Emmanuel K. Quagraine, Trever McNabb, Taneal Weiss, Gillian Bailey, Nikki Wirtz, Khrystyna Vasylkiv, and Daniel Schorr

This is the first half of a two-part article which discusses the abatement of selective boiler chloride cycling (SBCC), which has plagued the subject power plant, upon switching the recirculating cooling water (RCW) biocide from NaOCl to ClO2. Evidence has been given to attribute this mainly to gaseous ingress of volatile chlorinated compounds (VCCs) through weak tube-to-tubesheet joints. Based on Henry’s constants in aqueous solutions, ClO2 partitions more into the gaseous phase compared to chlorine species associated with NaOCl, i.e., chloramines, Cl2, HOCl, and OCl–. The SBCC abatement hence seems paradoxical. Based on literature and operational data, this is explained. Properties of ClO2 make keeping residual ClO2 in RCW difficult, if not impractical. At the cooling tower, major losses occur physically and chemically and even when residual remains, its high solubility in water at such low concentrations causes deviation from Henry’s law, i.e., a lower tendency to form ClO2(g). In addition, inside the condenser, where ClO2(g) may occur, it reacts quickly with oxidizable gases and (bio)organic compounds selectively yet versatilely, where it is not only consumed but avoids formation of VCCs, thereby preventing their ingress into the condensate side.

PPCHEM® 2023, 25(3), 158–174

For Members only

ERRATA

Nobody is perfect and everybody makes mistakes sometimes. We apologize to the authors and to our readers for the mistakes in these articles:

On the Usefulness of Bypass Clean-up Systems

Volker Ender and Jens Weber

PPCHEM® 2023, 25(2), 100–105

The corrected version of the paper (a PDF file)
is available to all readers here.
The details of the errata can be found in the pdf:

Some Basics of Power Plant Chemistry – Corrosion and Deposition

Frank Udo Leidich

PPCHEM® 2023, 25(1), 38–50

The corrected version of the paper (a PDF file)
is available to all readers here.
The details of the errata can be found in the pdf:
Posted on

Issue 02 (2023)

Connecting the Dots between Steam Generator Chemistry and Fundamental Thermodynamics

Brad Buecker

Experience has shown the importance of the necessity of comprehending the thermodynamics of steam generator heat transfer to better understand the chemistry requirements. Besides the corrosion aspects of water- and steam-side impurity ingress, efficiency losses can be expensive.

To minimize efficiency losses, condenser performance should be monitored diligently and it must be ensured that cooling water chemical treatment programs are operating properly and that air in-leakage has not become excessive. Reheating improves efficiency only by a few percent, but basic thermodynamic calculations show that steam reheating and introduction of the hot reheat to the intermediate-pressure turbine and crossover to the low-pressure (LP) turbine keeps the steam significantly drier in the LP turbine, with final moisture content usually below 10 % (and thereby minimizing water droplet erosion of the last stage blades).

In this article, we make the connection between major steam generator design details (and the thermodynamic principles behind them) and condensate/steam chemistry fundamentals.

PPCHEM® 2023, 25(2), 72–78

For Members only

A Low pH Excursion Exclusively in the IP Evaporator/Drum at a Combined Cycle Plant during a Start-up – Part II: Lessons Learned

Emmanuel K. Quagraine, Philip Boutin, Jordan Rothwell, Cedric Huang, Nikki L. Wirtz, Jackie Sliva, Kellsey Hamel, Dwayne Selensky, Amy Tetlock, and Pratik Pansuriya

This is the second of a two-part article on a low pH excursion which occurred exclusively in the intermediate-pressure (IP) evaporator/drum of a combined cycle plant, with the other circuits (low-pressure (LP) and high-pressure (HP)) showing normal pH. This is an odd situation, and the first half of the article explains how this was possible. Part II however describes how this unexpected situation confounded interpretations of the plant’s on-line instrumentation readings and the decision-making based on this data, which led to delays and inadequate response to the low pH excursion. A lot of confusion and uncertainties around pH readings were experienced and the causes have been identified. The plant also experienced a protracted period to clear the contaminant and attain desired steam purity for operation, the reasons for which are discussed. Lessons learnt and recommendations are also given to ensure early leak detection, prevention, or proper response to such pH excursions in the future.

PPCHEM® 2023, 25(2), 82–97

For Members only

On the Usefulness of Bypass Clean-up Systems

Volker Ender and Jens Weber

Instead of a simple water exchange, another possible method to correct the water quality in circulation systems is the method of bypass clean-up. To estimate the efficiency of a bypass clean-up, one must consider the inner efficiency as well as the outer efficiency. The inner efficiency is influenced exclusively by the method of cleaning being used, while the outer efficiency is ultimately decisive for an efficient application of bypass clean-up systems. The outer efficiency is determined by the relation between the different rate constants of the various processes which contribute to the decrease (or increase) in the concentration of the water constituents under consideration. Hence, one can find applications where a bypass clean-up can have high efficiencies, but there are also cases in which only low overall efficiencies may be achieved, despite high inner efficiencies. Using the framework presented here, it should be possible to estimate the effects on a theoretical basis.

PPCHEM® 2023, 25(2), 100–105

For Members only

IAPWS Film Forming Substances (FFS) Conference, FFS2023 Highlights and Press Release

The sixth IAPWS FFS International Conference was held on the 21st–23rd March 2023 in Prato, Italy chaired by Barry Dooley of Structural Integrity Associates, UK and David Addison of Thermal Chemistry, New Zealand. The FFS conferences are unique on a narrow topic in cycle chemistry control of power plants and steam generating facilities. In 2023 the conference attracted 70 participants from 28 countries which included 20 plant operators / users and representatives from 11 FFS chemical suppliers.

The FFS conferences are developed and supported by the International Association for the Properties of Water and Steam (IAPWS), and FFS2023 was arranged in Prato by Mecca Concepts, Australia and Combined Cycle Journal, USA. The sponsors of FFS2023 were Kurita Europe GmbH, Nalco Water an Ecolab Company and Termanox Water Treatment Solutions.

PPCHEM® 2023, 25(2), 108–109

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Issue 01 (2023)

Remember the 3Ds of Alkalizing Amines: Dissociation, Distribution, and Decomposition

Brad Buecker and Steve Shulder

Carbon steel corrosion control of condensate lines, feedwater piping, and boiler internals is critically important in all steam generation applications. A key corrosion control aspect is establishing and maintaining a mildly alkaline pH throughout these networks. Organicbased alkalizing amines have a place in lower- and intermediate-pressure boilers, industrial plant condensate-return systems, and nuclear power plant secondary cycles. However, careful evaluation and research is needed when selecting a program. This article examines the “3Ds” of alkalizing amines, dissociation, distribution, and decomposition, and how these properties influence the selection of the compounds for controlling condensate and feedwater chemistry. Dissociation and distribution are equilibrium or reversible reactions while decomposition is irreversible. The article examines these properties for high-pressure utility units and offers some comparisons/contrasts for lower-pressure industrial systems, which often have extensive steam and condensate-return networks.

PPCHEM® 2023, 25(1), 4–13

For Members only

A Low pH Excursion Exclusive to the IP Evaporator/Drum at a Combined Cycle Plant during a Start-up – Part I: Contamination Pathway

Emmanuel K. Quagraine, Philip Boutin, Jordan Rothwell, Cedric Huang, Nikki L. Wirtz, Jackie Sliva, Kellsey Hamel, Dwayne Selensky, Amy Tetlock, and Pratik Pansuriya

This is the first of a two-part article on the investigation of a low pH excursion which occurred exclusively in the intermediate-pressure (IP) evaporator/drum of a combined cycle plant at a start-up. The selective contamination occurred as glycol from closed-circuit cooling water (CCCW). The proposed contamination route is via a boiler feed pump (BFP), specifically O-ring seals separating the CCCW from the feedwater. The estimated leak rate is 8.0–22.9 mL ⋅ h–1, which is sufficient to cause the pH excursion. At start-up, the BFP would have charged the IP (and not the high-pressure (HP)) circuit line with water whilst in recirculation mode; this was later used to fill the IP drum. The HP drum was filled an hour later. Thus, accumulated glycol that leaked into the pump casing would have been pumped more exclusively into the IP circuit, resulting in the selective contamination. Through recirculation, glycol that potentially entered the low-pressure circuit, eventually feeding the HP circuit, would have been sufficiently diluted to prevent such an excursion in these two corresponding evaporators/drums.

PPCHEM® 2023, 25(1), 16–34

For Members only

Some Basics of Power Plant Chemistry – Corrosion and Deposition

Frank Udo Leidich

Undesired corrosion and deposition reduce the lifetime of a power plant or its specific components. Even before a component in the water/steam cycle (WSC) is damaged or destroyed, economic damage has already been caused in terms of a reduction in efficiency, deterioration in availability, and increased maintenance and repair costs. In order to limit corrosion and deposition to acceptable levels, monitoring and control of the physico-chemical parameters of the working media is necessary. It is also necessary to purify (treat) the working medium (water/steam) and add chemicals suitable for reducing corrosion reactions and deposit formation on the components and parts of the WSC. This paper gives an overview of the different types of corrosion, where they occur in the WSC, and the potential hazards they pose. The most widespread deposits, their composition, impact, and origin are also discussed.

PPCHEM® 2023, 25(1), 38–50

For Members only

2022’s Scientific and Technical Contributions

PPCHEM® 2023, 25(1), 52–59

For Members only

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Issue 05 / 06 (2022)

Alkalisation and pH Stability in Water-Steam Cycles

Wolfgang Hater

The pH adjustment in the water-steam cycle is an important and widely applied measure to maintain plant integrity. The impact of the most common alkalising agents on pH and conductivity is discussed as well as the behaviour of mixtures. A methodology to calculate pH and conductivity from base constant and equivalent conductivity including possible intrusion of acid substances is presented.

With increasing basicity of the alkalising agent, the molar quantities needed to obtain the desired pH value decreases, reaching the minimum value for sodium hydroxide. At the same time, the impact of an ingress of an alkaline or acidic substance increases. Of the alkalising agents discussed in this paper, ammonia shows the highest and sodium hydroxide the lowest stability against pH excursions.

Mixtures of alkalising agents change their properties with regard to pH stability linearly as a function of the composition. Their pH stability reflects the properties of the individual components: a mixture of sodium hydroxide and ammonia has a lower resilience against acid ingress compared to mixtures of trisodium orthophosphate and ammonia.

A high pH stability of the alkalising agent is an important measure to reduce the possible impact of acidic substances entering the system by leakage or decomposition of organic matter. Therefore, this has to be carefully considered when choosing the chemical for alkalisation

PPCHEM® 2022, 24(5,6), 196–206

For Members only

Some Brief Comments on Microbiologically Influenced Corrosion (MIC) in Power Plants

Reza Javaherdashti

This article deals with the most practical aspects of microbially influenced corrosion (MIC) in power plants. The issues discussed here are mainly where to expect MIC in power plants, the inaccurate nature of the term “biofilm” and the possibility of whether bacterial adaptation to biocides can occur. These issues are particularly important from an operation and maintenance point of view because they play an undeniably significant role in reducing the useful service life by increasing the risk of MIC and the cost of its treatment in power plants.

PPCHEM® 2022, 24(5,6), 208–213

For Members only

Oxidative Treatment of Waste Containing EDTA for its Safe Disposal – Choice of Oxidant and Mode of Addition for Field Applications

Rajini P. Antony and A. L. Rufus

High amounts of ethylenediamine tetra acetic acid (EDTA) containing liquid waste along with metal ions (predominantly iron) at pH ~ 8 are generated during the process of chemical cleaning of steam generators in pressurized heavy water reactors and pressurized water reactors. Hence, proper waste disposal involving complete or partial decomposition of EDTA is indispensable. Three different oxidants, viz., air, H2O2, and ozone, were explored for the decomposition of a test solution. Their efficacy was found to be in the order: H2O2 > ozone > air. The lower rate of decomposition in the case of ozone and air is due to their solubility limitations. Investigations on the mode of addition of H2O2 revealed that a bulk/one-time large addition of H2O2 and continuous addition of small quantities at a controlled flow rate yield identical results. On weighing the practical risks/hazards involved in bulk addition during field applications, continuous addition is suggested as a better option.

PPCHEM® 2022, 24(5,6), 214–223

For Members only

Industrial Plants and Steam Purity for Turbine Operation – A Too Frequent and Almost Classic Dilemma

Michael Rziha

Worldwide there are countless industrial installations using steam as a “byproduct” to drive a steam turbine. The steam is generated by many different sources, such as quench boilers and trans-line-exchangers, which are often found in refineries and petrochemical plants. Waste heat boilers in refineries and petrochemical plants can be water tube boilers and shell boilers. Fired flame tube boilers with low or medium pressure (5–50bar) are also used in many installations.

Industrial steam generators often have special requirements regarding load gradients (extremely fast load requirements and/or load reduction). Process steam extraction and process steam condensate return are very common in these plants, and carry the additional risk of the ingress of various contaminants from the different processes, finally leading to a heavy impairment of the steam purity.

Guidelines which are applicable for the feed- and boiler water for the different boiler types and operating pressures are misleadingly taken as “lead documents” although they do not provide the special individual consideration needed for steam purity. It must be emphasized that all such guidelines and standards are only valid for safe boiler operation, and do not address the needs of steam turbines.

In consequence, low-pressure boilers are often operated with softened water. From the perspective of boiler suppliers and boiler operators this might certainly be correct, as the generated steam is used for heating only, where the requirements on steam purity may be more relaxed.

However, and without exception, as soon as the steam is to be used to drive any kind of steam turbine, the relevant standards and guidelines for steam need to be followed. As a matter of principle this will always have an impact on the make-up water, feedwater, and boiler water purity. For example, boilers with a low operating pressure are allowed to be operated with softened or partially demineralized water. This is true and correct for the boiler/steam generator, but it is definitely wrong for any steam turbine tied into this process.

Steam turbine users should be aware of the risks associated with contaminants of the steam, which may initiate, promote, or enhance stress corrosion cracking, corrosion fatigue, general corrosion, erosion, and deposit buildup. Contaminants that are contained in steam generally lead to deposits and corrosion in steam turbines and thus potentially negatively affect their functioning and operational safety, as well as their lifetime. It must also be emphasized that corrosion and/or deposit build-up and consequently damage and/or impairment of performance or availability depend not on the size of the turbine, but only on the impurity level and composition of the steam.

Especially when softened water is used, the concentration of sodium in the water is significantly increased by the softening process! The thermal decomposition of sodium carbonates and sodium bicarbonates (products due to softening) always leads to the formation of caustic soda (NaOH), which strongly increases the risk of alkaline stress corrosion cracking of the turbine material! Consequently, when softened water is used as make-up water, a steam turbine operation is clearly excluded!

PPCHEM® 2022, 24(5,6), 224–229

For Members only

Report on the Power Cycle Instrumentation Seminar (PCIS) Austria 2022 in Linz, Austria

Tapio Werder

For the first time in the history of these events, the Power Cycle Instrumentation Seminar (PCIS) series stopped over in a German-speaking country. The PCIS Austria 2022 in Linz was held under the patronage of PPCHEM AG, and SWAN Analytical Instruments provided financial support.

Since 2012, PPCHEM AG and its precursor organization, Waesseri GmbH, have organized more than 30 conferences and seminars around the world with the mission of expanding the knowledge of cycle chemistry and the understanding of analytical instruments. Over the past 10 years, different formats of events have been developed to fit the different needs and interests within the power plant chemistry community.

This report summarizes the two days of the PCIS Austria 2022

PPCHEM® 2022, 24(5,6), 238–240

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Issue 04 (2022)

Dechlorination Control and Optimization in Industrial Water Applications

Vadim Malkov and Gregory Fleck

The use of reverse osmosis (RO) membranes for water treatment has almost doubled in the last five years [1]. The use is widespread across many industries, from municipal water and wastewater treatment to ultrapure water production in various industrial applications. For efficient RO membrane operation, it is important to accurately monitor and control the residual chlorine concentration in the feedwater, which allows for minimizing of RO membrane maintenance and extension of membrane life. Multiple studies demonstrate that prolonged exposure of RO membranes to free chlorine exceeding 38 μg · L–1 (ppb) (based on 1 000 mg · L–1-hours over three years [2]) is detrimental to the membrane structure and integrity, while the absence of the disinfectant and/or excess of dechlorinating agents promotes biofouling and causes loss of recovery. To maintain this delicate balance, membrane operators must accurately monitor oxidant concentration and addition of bisulfite, especially in the RO feedwater.

PPCHEM® 2022, 24(4), 136–159

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Causes and Effects of Insufficient Steam Purity and the Necessary Measures

Michael Rziha

As is well known, contamination in the steam very quickly leads to impairment of the steam turbine, ranging from loss of efficiency to a massive reduction in service life, or even to rapid destruction.

The causes and sources for the entry of contamination are very diverse, especially in industrial plants. Plant-specific knowledge of the possible entry points and the types of possible contamination is of crucial importance for the determination of a suitable monitoring strategy for the most trouble-free and damage-free operation of the steam turbine.

In addition, if such contamination occurs, suitable measures must be taken very quickly in order to avoid long-term, undesirable and, above all, cost-intensive damage to the steam turbine.

The most common sources and causes, their detection, and recommendations or necessary avoidance strategies from the perspective of power plant chemistry are presented.

PPCHEM® 2022, 24(4), 164–169

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HINTS FROM THE EXPERTS

Saving Money with Clever Blowdown Management

Clean chemical conditions within the water-steam cycle and the steam generator systems are of utmost importance for trouble-free operation and to maintain the required steam purity for steam turbine operation. If the control of the chemical regime is not managed correctly, the introduced contaminants will lead to the build-up of layers on the blading of the turbine, reducing steam turbine efficiency and leading to corrosion processes which can cause considerable damage in the water-steam cycle and steam generator systems. In the worst case the steam generator or the turbine will be reduced to scrap metal.

To control these contaminants and to avoid an excessive concentration within the evaporator, the blowdown of evaporator water is used to keep the concentration of the contaminants within allowable limits.

However, this method of concentration limitation has the negative side-effect of a loss of valuable enthalpy. It also increases the consumption of demineralized water and chemicals.

PPCHEM® 2022, 24(4), 170–173

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Application of Chloramine as a Biocide for Cooling Tower Water Consumption Reduction

Anderson José Beber

This paper shows the results of the application of a mild oxidizer on a large cooling tower at a power plant in southern Brazil. This cooling tower utilizes grey water (tertiary treated domestic sewage) as make-up. With the application of this technology, there was an improvement in both microbiological control and corrosion rates. Additionally, the plant was able to increase the concentration cycles from an average of 4.5 up to 6.5, resulting in an annual savings of over 400 000 USD.

PPCHEM® 2022, 24(4), 174–182

For Members only