Supplemental Oxygen for All-Volatile Treatment under Oxidizing Conditions
Jeremy B. Smith and D. Matt Craven
With aging fleets of fossil- and gas-fired units throughout the industry, flow-accelerated corrosion failures remain a major concern. Southern Company’s water chemistry program strives to provide its fossil and gas fleet with the best innovative solutions to control water/steam cycle chemistry within the latest industry guidance. This paper explains the Southern Company Water Chemistry group’s approach to achieving and maintaining the best control over the condensate and feedwater dissolved oxygen concentration for allvolatile treatment under oxidizing conditions (AVT(O)) chemistry programs.
Water Treatment of Flue Gas Condensate – White Paper
Nordic IAPWS
Flue gas condensation is the cooling of flue gas below its dew point. It produces heat from the condensation of the water content of the flue gas and it produces flue gas (FG) condensate. The FG condensate must be treated for discharge or reuse, hence the term FG condensate treatment.
FG condensate treatment is a specialty of the Nordic countries, where it has been developed since the mid-1980s. Today, the technique is well established and widespread in this region. This white paper summarizes the experiences gained in the Nordic countries to provide best practices to current and new users and build a bridgehead for other countries that may use the technology in combined heat and power production.
Review of the vgbe Chemistry Conference 2024, 22–24 October in Potsdam
This year, the traditional vgbe Chemistry Conference celebrated its 60th anniversary. From October 22 to 24, 2024, approximately 160 participants from Germany and abroad gathered in Potsdam to discuss and learn about the latest trends and challenges in power plant chemistry.
The vgbe Chemistry Conference team expresses its gratitude to all participants, speakers, and exhibitors for their contributions, which made this event a success. The team is already looking forward to the next vgbe Chemistry Conference, scheduled to take place in Kassel from October 28 to 30, 2025.
The German-Swiss Association for the Properties of Water and Steam e.V.
This issue includes a tribute to a highly respected member of the International Association
for the Properties of Water and Steam (IAPWS) community who recently passed away.
Professor Wolfgang Wagner’s dedication, warmth, and significant contributions have left a
lasting legacy within our field. He was a pioneer in improving data correlation techniques
for the thermodynamic properties of water and steam. Under his leadership, IAPWS
developed the current international formulations for the thermodynamic properties of water
and steam. His presence will be deeply missed, and we honor him for his invaluable
impact on our community. This tribute is from the joint national committee of Germany and
Switzerland, of which he was an honorary member.
Inferred Boiler pH from Conductivities in Solutions Containing Sodium Phosphate,
Alkalizing Amines, and Amine Decomposition Products
Daniel Zinemanas and Eyal Keren
Accurate knowledge of the pH in boiler water is an important and central chemical
parameter for the monitoring and control of the boiler chemical conditions and is critical to
minimizing the corrosion processes. pH measurements, however, are not always easily or
accurately measured, so alternative means of correctly estimating the boiler pH can be
useful for achieving these goals. In certain situations, the conditions are even quite
complex and challenging since the impurities which negatively affect the chemical
parameters arise from the treatment chemicals themselves, such as, for example, the
products of the thermal decomposition of organic alkalizing amines used for pH control.
Thus, it is the purpose of the present study to show an alternative way by means of the
calculation of the inferred pH from the specific conductivity and the conductivity after cation
exchange and to describe its application, together with these conductivities, to the
monitoring and control of the boiler water in relatively complex solutions in which sodium
phosphates, alkalizing amines, and amine decomposition products are present. The
methodology described in the paper is applied in a cogeneration plant with a dual pressure
heat recovery steam generator equipped with an air-cooled condenser, where, as
demonstrated, very good results were achieved. The study also emphasizes the main
concerns and disadvantages regarding the use of organic alkalizing amines in water/steam
cycle water treatment.
IAPWS TGD2-09(2024): Instrumentation for Monitoring and Control of Cycle Chemistry for the Steam/Water Circuits of Fossil-Fired, Combined Cycle, and Industrial Power Plants
The International Association for the Properties of Water and Steam
This Technical Guidance Document was first issued in 2009 and revised in 2012 and
2015. This 2024 revision includes a small number of updates and clarifications. These do
not constitute significant changes to the scope of the document or to the guidance
contained.
In order to achieve suitable chemical conditions in steam/water circuits, it is essential to
establish reliable monitoring of key parameters on every plant. This enables the
demonstration of operation within cycle chemistry targets, and alerts the operators to the
need to take corrective action when the target conditions are compromised.
This technical guidance document considers conventional fossil, combined cycle / HRSG,
and industrial plants and identifies the key instrumentation and monitoring techniques
required for each plant type and cycle chemistry treatment. It is emphasized that this is an
IAPWS guidance document and that, depending on local requirements, the use of simpler
instrumentation may be adequate, whereas more complex techniques and instrumentation
may be necessary when specific issues arise.
Amine Analysis and Monitoring – A Practical Approach
Wolfgang Hater and Levie Lensun
Amines are used for three different purposes in a water/steam cycle (WSC): as reducing agents (reducing amines (RA)), to adjust the pH in the WSC (alkalising amines (AA)), and to protect the inner surfaces of the WSC by the formation of an adsorptive film on the metal surfaces (film forming amines (FFA)). Monitoring and control have to be chosen according to the purpose of use. The chemistry and selected properties that are important for the application and control of the amine groups are presented.
This article discusses the different approaches for monitoring and control of the three groups of amines together with the common methods of analysis. For the monitoring of RA and AA, standardised methods of analysis are available. exchange.
For FFA monitoring, two main methods are available, which are primarily applied for grab samples. They are well established; however, there is a limit of detection so that in some cases free residual FFA cannot be detected in the whole WSC, and, thus, the completeness of film formation is not proven.
A process for the upgrading of FFA to improve the limit of detection is proposed which is suitable for on-site application. Furthermore, several approaches for indirect analysis of FFA in water are presented in which test specimens are introduced into the WSC. Either the FFA adsorbed on the surface is measured or, alternatively, the FFA presence is proven via the change in surface properties due to the effect of FFA adsorption. In this way the completeness of film formation in the WSC can be demonstrated.
Cooling Tower Operating and Water Treatment Fundamentals – Part 3
Brad Buecker
Cooling water systems are an integral component of many power plants and thousands of industrial facilities. The previous installment focused on microbiological fouling, as this phenomenon often causes the most prompt and severe difficulties in cooling systems. However, scale formation and corrosion (including corrosion caused by microbiological deposits) can also be very problematic if not properly monitored and controlled. Treatment programs for both are often interlinked, so this and the next installment highlight the most common corrosion and scaling mechanisms, followed by Part 5, which will examine modern corrosion/scale control chemistry.
2024 Electric Utility Chemistry Workshop – Highlights and Press Release
The 2024 Electric Utility Chemistry Workshop again offered a broad range of important topics for steam generation chemists, engineers, and managers. This article offers several highlights from the event. A somewhat overlooked benefit of this conference is its potential value for those employed at co-generation and large industrial plants, where water and steam treatment issues are similar and equally as important as for the power industry. Accordingly, the planning committee is renaming the event the Electric Utility and Co- Generation Chemistry Workshop (EUC2W) to emphasize the workshop’s value to diverse industrial personnel.
IAPWS Highlights 2024 – 18th International Conference on the Properties of Water and Steam (ICPWS) & Annual Executive Committee and Working Group Meetings
Continuing a series of conferences started in 1929, the 18th International Conference on the Properties of Water and Steam (ICPWS) was held in Boulder, Colorado, on June 23– 28, 2024. The Conference is organized by the International Association for the Properties of Water and Steam (IAPWS) and for the first time was combined with another conference: the 22nd Symposium on Thermophysical Properties (STP). The STP is held in the U.S. every three years and brings together experts in the theory, modeling, and measurement of thermophysical properties of fluids and solids. The joint meeting allowed a wider community of researchers to be exposed to the work of IAPWS and gave people from IAPWS the opportunity to learn about leading-edge research and applications in fields outside water and steam. The combined conference attracted 440+ attendees from 29 countries.
Monitoring Dissolved Hydrogen in Water-Steam Cycles
Michael Rziha
The idea of using the measurement of dissolved hydrogen to assess the formation of protective coatings is nothing new. As early as 1953 (!), H. Kiekenberg published an article in the German “VGB Mitteilungen” on hydrogen measurements in Benson and drum boilers, followed by further publications by other well-known authors in the following years. Corrosion occurs in the presence of water or steam in contact with iron at high temperatures. According to the Schikorr reaction, hydrogen is released as a by-product during the formation of a protective layer in a power plant. Hydrogen monitoring thus becomes important in corrosion monitoring for water-steam cycles; the hydrogen concentration is a very sensitive indicator of corrosion.
Effect of ODACON® F on Carbon Steel Corrosion in Water-Steam Cycle Chemistry with Ethanolamine
Jaganathan Ulaganathan, Ute Ramminger, and Jörg Fandrich
Film-forming amine (FFA) applications are a recent strategy used by nuclear power plants for the corrosion protection of secondary-side components during outages and normal operation. Laboratory investigations of FFA applications are usually conducted in static autoclaves under conditions that are different from the field, where the conditions are dynamic with factors such as temperature and single-/two-phase flow varying throughout the water-steam cycle. To address this gap, the H3 Loop, a recirculating loop at Canadian Nuclear Laboratories was used to investigate the effect of ODACON® F, a commercial FFA, on the corrosion of pre-oxidized (PO) carbon steel (CS) tubing exposed to ethanolamine chemistry under two-phase flow conditions at 180 °C and 15 % steam quality. Post-test weight measurements showed negligible corrosion due to the preexisting oxides. Water beading tests and scanning electron microscopy examination demonstrated that the PO CS surfaces exposed to ODACON® F under different temperatures and single-/two-phase flow conditions were hydrophobic due to film formation and not the pre-existing oxides.
Improving the Reliability of Degassed Conductivity after Cation Exchange Measurement with EDI Technology
Mar Nogales and Julia Gath
During the startup of a water-steam cycle, CO2 is the primary contributor to increased conductivity after cation exchange (CACE) values. It is generally accepted that CO2 is the least aggressive contaminant in a water-steam cycle. Therefore, it is essential to reliably demonstrate that the increased CACE is due to CO2 and not to more harmful contaminants like chloride or organic acids. Elimination of the carbon dioxide contribution is possible via thermal degassing of the sample, and subsequent measuring of the degassed CACE (DCACE). The reproducibility of the degassing process is an essential prerequisite for reliable measurements.
A CACE measurement system utilizing an electrodeionization device (EDI) for the cation exchange was introduced to the market in 2016 and has proven to be dependable. This paper describes how this established technology has been enhanced with a reliable degassing unit, resulting in a DCACE measurement utilizing an EDI device for the cation exchange.
The tenth annual IAPWS European HRSG Forum was held on the 13th–15th May 2024 in Prato, Italy. It was chaired by Barry Dooley of Structural Integrity and Bob Anderson of Competitive Power Resources. EHF2024 attracted 90 participants from 18 countries and included 40 users. The EHF2024 event was organized by Mecca Concepts, Australia. The 2024 EHF had 13 sponsors: Dekomte, NEM, John Cockerill, Tuff Tube Transition, Precision Iceblast Corporation, Altrad Babcock, TesTex, Arnold Group, Valve Pro/Conval, Advanced Valve Solutions, Cormetech, Groome Industrial Services and Metroscope.
Novel Identification Method for Seawater Contamination into Water-Steam Cycles
Yuta Nakatsuchi, Akihiro Hamasaki, Haruka Kido, and Takayoshi Iwa
In the water-steam cycle of power plants, cation conductivity is measured to promptly detect contamination by impurities such as seawater and prevent corrosion damage to equipment and piping. Cation conductivity is obtained by measuring the electrical conductivity of the sample after the cation exchange pretreatment, making the highly sensitive detection of anion impurities possible. However, due to a policy of increased introduction of renewable energy, frequent start and stop operation of combined cycle power plants is increasing. As a result, interference with cation conductivity measurements by carbon dioxide which enters from the air during plant outages will increase, making the delayed detection of contamination by impurities a matter of concern. Therefore, a novel identification method for impurities based on the pH, specific conductivity, and cation conductivity, which are monitored conventionally in the water-steam cycle, has been investigated.
As a result of the calculation of impurity concentrations using the novel model of the simulated water quality of a water-steam cycle prepared by chemical equilibrium calculation software, it has been confirmed that the calculation error for carbon dioxide concentrations not from seawater is 0.0% to 18% more than 0.1 mg ⋅ L–1, and that for seawater contamination is 0.0% to 20% more than 1 ⋅ 10–6 m3 ⋅ m–3, which is regarded as good agreement. Additionally, the calculated results with measured data from two power plants are consistent with the assumed behavior based on the plant status. In conclusion, it is indicated that the amount of seawater can be precisely estimated even in the case of the presence of both carbon dioxide and seawater by using this novel method.
The British and Irish Association for the Properties of Water and Steam (BIAWPS) hosted their 23rd Annual Power Plant Chemistry Symposium on 22nd–23rd May at Warwick University, Coventry, UK. The Symposium was attended by around 90 members of the UK and Ireland water/steam cycle chemistry community, with a good mix of Operators, Vendors, and Suppliers to the water treatment industry.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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).
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.
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.
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.
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.
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.
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.
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.
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.
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).
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.
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.
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.
