Category: Year 2025

Method for Predicting the pH of Boiler Water at Actual Temperatures

Kenichi Ito

Normally, the pH of boiler water is controlled based on the pH at 25 °C. However, since the dissociation constants of water, acid components, and alkaline components vary with temperature, the pH behaviour at high temperatures differs significantly from that at 25 °C. The author developed a calculation program using the Microsoft Excel^® macro function Visual Basic for Applications (VBA) to theoretically predict the pH of boiler water at actual temperatures (pH_T).

As an application example of this program, the relationship between temperature and pH_T for various alkalising agents as well as the relationship between the dosage of each alkalising agent and pH_300°C were shown. The results indicated that ammonia and alkalising amines have lower alkalising capabilities at high temperatures compared to Na₃PO₄ and NaOH. Additionally, the example shows the relationship between the concentrations of acidic substances (HCl, acetic acid, formic acid, and orthosilicic acid) and pH_300°C when using each alkalising agent.

PPCHEM^® 2025, 27(5), 264–274

Towards Hydrazine-Free Operation of the Water-Steam Cycle in Nuclear Power Plants

Judith Riedhammer, Robert Lehr, and Jörg Fandrich

Hydrazine is used in water-steam cycles of pressurized water reactors to protect the steam generators by generating reducing and oxygen-free conditions. However, growing regulatory and environmental concerns about its toxicity and mutagenic properties are leading to actions to restrict it or completely phase it out. Additionally, the declining availability of nuclear-grade hydrazine has led to supply shortages and disruptions in some cases.

To further ensure the material integrity of nuclear steam generators, this paper describes possible alternatives to hydrazine by leveraging the radiation field within nuclear steam generators. Theoretically, low-molecular-weight compounds comprising carbon, hydrogen, oxygen, and optionally nitrogen are capable of reacting with oxygen by undergoing a radiation-induced reaction. Experiments under steam generator conditions have confirmed methanol and ethanolamine as effective reductants, as they lower the redox potential and the corrosion potential of the most common nuclear steam generator tubing materials, as well as oxygen levels. Both chemicals have already been used in the nuclear industry.

PPCHEM^® 2025, 27(5), 282–294

Publisher’s Announcement
A New Chapter: The PPCHEM^® Journal Goes Fully Digital in 2026

After more than two decades of continuous print publication, we would like to inform you that the PPCHEM^® journal will discontinue its print edition at the end of 2025. The final printed issue will be Issue 6, scheduled for publication in December 2025. This decision reflects a broader shift in how our readership consumes content and the increasing demand for more flexible, accessible, and sustainable digital formats. While the printed journal will come to an end, PPCHEM® will continue to provide high-quality content through its online platform, maintaining our commitment to professional knowledge sharing.

PPCHEM^® 2025, 27(5), 302

IAPWS European HRSG Forum (EHF2025) Highlights and Press Release

The eleventh annual IAPWS European HRSG Forum was held on the 13th–15th May 2025 in Prato, Italy. It was chaired by Barry Dooley of Structural Integrity and Bob Anderson of Competitive Power Resources. EHF2025 attracted 95 participants from 20 countries and included 27 users.

EHF2025 was developed and continues to be supported by the International Association for the Properties of Water and Steam (IAPWS) and is held in association with the Australasian Boiler and HRSG Users Group (ABHUG) and the US HRSG Forum (HF). The EHF2025 event was organized by Mecca Concepts, Australia and had 17 sponsors: Precision Iceblast Corporation, NEM, Dekomte, Freudenberg Flow Technologies, TÜV Rheinland, New Componit, Advanced Valve Solutions, Tuff Tube Transition, TesTex, Quest Integrity, Metroscope, OMB, Pruss, Fuel Tech, Arnold Group, IMI and Thermic Systems.

PPCHEM® 2025, 27(4), 210–212

Chemical Compositional Changes in Coal Fly Ash through an Integrated Amine- Based Post-combustion SO2 and CO2 Capture Process

Emmanuel K. Quagraine and Jonathan Ruffini

Combustion of coal in air leads to a gaseous product stream (flue gas) that mainly contains nitrogen (N2), carbon dioxide (CO2), water vapor, and small quantities of many other gases such as sulphur oxides (SO2 and SO3) and nitrogen oxides (NOx mainly, NO, and NO2) as well as particulates (mainly coal fly ash (CFA)) at different concentrations depending upon the content of the coal and the quantity of air used for its combustion. The need to maintain reliable power while reducing greenhouse gas emissions has been driving governments and companies worldwide toward CO2 capture and storage/utilization. One such initiative is SaskPower’s Integrated Carbon Capture and Storage (CCS) project at its Boundary Dam Unit 3 (BD3), which is amine based and just passed 10 years of commercial operation. The listed impurities in coal flue gas, of which CFA is the current focus, can cause degradation of the amines and have many other adverse effects on the capture process. Indeed, current electrostatic precipitators or fabric filters are designed to remove most of the CFA (typically up to ~ 99.9 % or 99.99 %, respectively), yet accumulation of the relatively small unremoved fraction within the CCS process is documented as causing physical barriers to the operation. One aspect of the effect of CFA on the amine-based CO2 capture system which is very poorly elucidated is its interactions with the gaseous acidic impurities in the flue gas and with added treatment chemicals as it traverses various sections of the process under different conditions such as pH and temperature, and how these can affect the overall performance of CCS systems. In this current paper we present the chemistry behind changes in the composition of CFA as it travels through the flue gas pretreatments and the integrated amine-based postcombustion SO2 and CO2 capture process at the BD3 CCS facility. Generally, through the various stages of treatment, CFA is modified in various ways including a) extensive depletion of water or acid leachable ions of metals like aluminium (Al), iron (Fe), magnesium (Mg), sodium (Na), and potassium (K) at the pre-scrubbing stage (pH ~ 2); b) co-deposition with CFA of sulphate and phosphate salts of Na, Fe, and barium (Ba) due to leaching of the respective ions from CFA (and from steel material corrosion in the case of Fe) at the flue gas cooling and the SO2 absorption stages, at high enough levels to exceed their saturation point or solubility products; and c) silicon dioxide or silica (SiO2) removal at certain sections within the CO2 capture stage due to its leaching from CFA under some high pH and temperature conditions.

PPCHEM® 2025, 27(4), 2016–240

IAPWS Press Release – Annual Executive Committee and Working Group Meetings 2025

Between June 22nd and 27th, 96 scientists, engineers and 10 guests representing 20 countries met at the Hanaholmen Convention Centre in Helsinki, Finland for the annual meetings of the IAPWS Executive Committee and Working Groups. This series of meetings 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.

IAPWS produces releases and guidelines on the recommended scientific formulations for physical and chemical properties of water in its various forms as well as technical guidance documents that are the concerted opinion of IAPWS members on the best operating practices for power plant chemistry. IAPWS also documents certified research needs that represent the opinion of experts in their respective fields that a research topic is greatly needed to fill a current gap in knowledge. All this information is freely available and can be found on the IAPWS website at www.iapws.org.

PPCHEM® 2025, 27(4), 248–250

Enhancing ESP Efficiency through Sonic Horn Optimization for Improved FGD Performance and Gypsum Quality

Batıkan Aydın

Electrostatic precipitators (ESPs) play a vital role in capturing fly ash from flue gases in thermal power plants. Traditional ESPs often encounter efficiency challenges due to fly ash accumulation on collection plates, necessitating frequent rapping systems to dislodge the ash. These rapping systems can be inefficient and lead to operational downtimes. The integration of sonic horns into ESP systems has demonstrated significant efficiency improvements. Sonic horns utilize acoustic waves to effectively dislodge accumulated fly ash from the plates, promoting continuous and thorough cleaning. This method mitigates the re-entrainment of fly ash, resulting in a more consistent and reliable collection process.

Pilot studies have shown that ESP systems equipped with sonic horns provide significant improvements in equipment lifespan and dust collection efficiency. This enhancement translates to reduced maintenance costs, decreased operational downtimes, and improved overall plant performance. Additionally, the implementation of sonic horns reduces the risk of damage to ESP components, thereby extending their operational lifespan. The incorporation of sonic horn technology represents a substantial advancement in ESP efficiency, offering a cost-effective and robust solution for fly ash management in thermal power plants.

PPCHEM® 2025, 27(3), 130–134

White Paper (PCC WP 24-001): Corrosion Product Sampling, Monitoring and Analysis for Flexible and Fast Starting Plants

IAPWS PCC Working Group

This White Paper has been released by the International Association for the Properties of Water and Steam (IAPWS) Power Cycle Chemistry (PCC) Working Group. An IAPWS PCC White Paper is intended to be a preliminary technical document collating knowledge on a particular subject to provide a basis for the potential future development of a related Technical Guidance Document. They are not formal IAPWS outputs as such.

This White Paper considers the sampling and monitoring of total iron and copper corrosion products for flexible and fast starting conventional fossil and combined cycle/HRSG plants. It provides correct sampling conditions and appropriate proxy methods such as turbidity and particle counting/monitors to track metal oxides during steady and transient load, and even during startup.

The White Paper introduces a procedure for quantification of corrosion products that reflect the success or failure of the preservation methods applied during shutdown. The IAPWS Corrosion Product Decay Map grades the outcome of this measurement during startup in a simple and illustrative manner allowing an operator to plot the local results directly against the international experience and to improve the operational and shutdown chemistry in a move towards more optimized conditions in the future.

This IAPWS White Paper Document contains 50 pages, including the cover page

Further information about this White Paper and other documents issued by IAPWS can be obtained from the Executive Secretary of IAPWS (Dr. D.G Friend, gro.swpai@dneirf.gd) or from http://www.iapws.org.

PPCHEM® 2025, 27(3), 140–189

Report on the Power Cycle Instrumentation Seminar (PCIS) Germany 2025

Tapio Werder

For the second time, the Power Cycle Instrumentation Seminar (PCIS) series made a stop in Germany. The PCIS Germany 2025 in Aachen 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 focuses on the analytical methods, the sampling points, and the critical issues for each parameter. The emphasis lies on spreading knowledge of cycle chemistry and an understanding of analytical instruments. The seminar 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 2025.

PPCHEM® 2025, 27(2), 68–71

Pre-Stripper Sulfite-Induced Coal Fly Ash Leaching – Part 2: Leaching of Iron and Other Transition Metals as Monitored by Inductively Coupled Plasma Mass Spectrometry

Emmanuel K. Quagraine, Nikki Wirtz, Cedric Huang, and Dwayne Selensky

This is Part 2 of a series of investigations on understanding the impact SO₂ in flue gas (FG) has on an integrated amine solvent based sulfur dioxide (SO₂) and carbon dioxide (CO₂) capturing process such as practiced at the Boundary Dam Unit 3 carbon capture and storage plant. It follows the Part 1 article on the effect of SO₂ on coal fly ash (CFA) leaching of iron and extends it to other transition metals (TMs) that may potentially cause oxidative degradation of amines used in the process. The results confirm the findings in Part 1 that, apart from pH on its own, SO₂ and its pH-speciated aqueous forms affect the leaching of TMs and potentially catalyze degradation of amines used to capture acidic contaminants from post-combustion FG. The sulfite-induced leaching of TMs occurred primarily under acidic conditions that simulate pre-scrubber and amine-based SO₂ capture conditions (pH ≤ 6). This occurred either exclusively (e.g., for iron) under acidic conditions, or additionally also in alkaline solutions – substantially for copper when at 50 °C, but only moderately for vanadium and titanium (and copper when at 90 °C). The alkaline leachates that represent conditions of the post-combustion CO₂ capture process are as follows for a caustic chimney tray fly ash (CCTF) sample: copper (Cu) > iron (Fe) > vanadium (V) > titanium (Ti) > nickel (Ni) > chromium (Cr) > manganese (Mn); and for a flue gas cooler inlet fly ash (FGCIF) sample: V > Fe > Mn > Ti > Cu > Ni > Cr. However, TMs leached more under the acidic conditions (pH 4 to 6) that better represent the SO₂ capture process, and the leaching order is as follows for CCTF: Fe > Cu > V > Ti > Mn > Cr > Ni; and for FGCIF: Fe > Mn > Ti > V > Ni > Cu > Cr.

PPCHEM® 2025, 27(2), 74–91

Highlights and Press Release Annual Meeting and Conference in Bochum, Germany

GSAPWS e.V.

The German-Swiss Association for the Properties of Water and Steam (GSAPWS) e.V. held its annual general meeting and conference on March 6 and 7, 2025. This year, the events took place at Ruhr University Bochum.

PPCHEM® 2025, 27(2), 94–95

Novel Prediction Model Based on the Two-Film Theory for the Ammonia Distribution Coefficient in Heat Recovery Steam Generators of Gas Turbine Combined Cycle Power Plants

Yuta Nakatsuchi, Haruka Kido, Akihiro Hamasaki, and Shinji Fujimoto

In a combined cycle power plant with a heat recovery steam generator, ammonia and hydrazine are injected into the boiler feedwater, while sodium phosphate is used in the drum boiler water. However, hydrazine is suspected to cause health problems, and sodium phosphate may cause phosphoric acid corrosion. An alternative method has been applied in recent years wherein only ammonia is used for water treatment. Although the ammonia concentration in the drum boiler water depends on the gas-liquid distribution coefficient of ammonia, the measured result of the gas-liquid distribution coefficient in the actual plants is found to be smaller than the reported value in the equilibrium state. This is because the boiler feedwater passes through the drum boiler before attaining equilibrium. In this study, a novel dynamic model for the gas-liquid distribution of ammonia between the drum boiler water and the drum boiler steam was investigated by applying the two-film theory. Using this novel model, the ammonia gas-liquid distribution coefficient in the drum boiler can be estimated more accurately. Furthermore, the ammonia concentration of the boiler feedwater can be determined, even in a water treatment system with only ammonia, which is effective in preventing flow-accelerated corrosion of the drum boiler.

PPCHEM® 2025, 27(2), 102–112

Erratum

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

PPCHEM® 2025, 27(2), 73

Cooling Tower Operating and Water Treatment Fundamentals – Part 4

Brad Buecker

Cooling towers and cooling water systems are an integral feature of many power plants and thousands of industrial facilities. The previous installments of this series focused on microbiological fouling and corrosion issues, as these mechanisms can cause severe problems. But by their very nature, cooling towers, in which water evaporation is the primary heat transfer method, cause an increase in concentration of both dissolved and suspended solids. Deposition and scaling can become quite problematic without careful chemistry control. This installment examines scale-forming mechanisms. In Part 5, we will examine modern corrosion/scale control chemistry. Some chemical inhibitors serve a dual function.

PPCHEM® 2025, 27(1), 4–8

Pre-Stripper Sulfite-Induced Coal Fly Ash Leaching – Part 1: Leaching of Iron(II) and Iron(III) as Monitored by Spectrophotometry

Emmanuel K. Quagraine, Nikki Wirtz, and Dwayne Selensky

Iron (Fe) is known to catalyze oxidative degradation of amines in the post combustion CO₂ capture (PCCC) process. However, sources of Fe for such degradations are poorly characterized. One aspect of the PCCC process which is poorly researched is the interaction of sulfur dioxide (SO₂) gas in the flue gas (FG) with coal fly ash (CFA) and how this can affect amine degradation. Understanding that the SO₂ would be dominantly present in the anionic pH speciated forms (bisulfite (HSO₃^–_(aq)) and sulfite (SO₃^2–_(aq))) as a result of caustic scrubbing or amine-based desulfurization and that ammonia is commonly present either in original FG or as an amine degradation product, CFA leaching of Fe by ammonium sulfite ((NH₄)₂SO₃) was experimentally examined under different pH (~ 4 to 10) and temperature (50 °C to 90 °C) conditions to simulate various pre-stripper sections within an amine solvent based SO₂ and carbon dioxide (CO₂) capturing process such as at the Boundary Dam Unit 3 carbon capture and storage (BD3 CCS) facility. The results suggest that SO₂ and its pH-speciated aqueous forms can leach Fe, and thereby catalyze oxidative degradation of common amines used in capturing acidic contaminants from post-combustion FG. With the addition of (NH₄)₂SO₃ (0.25 mol ⋅ L^–1), the effect of SO₃^2– on the leaching of iron(III) (Fe³⁺) and iron(II) (Fe²⁺) was apparent and distinctly different from the effect of pH per se. Thus, irrespective of the amine type, SO₂ and its pH speciated forms can generate Fe ions to catalyze the degradation. Still, SO₃^2–-induced Fe leaching occurred more dominantly in acidic solutions that simulate the pre-scrubber and amine-based SO₂ capture conditions (pH ≤ 6) and less in alkaline aqueous conditions simulating amine-based CO₂ capture (i.e., pH of ~ 8 to 10). The work does not seem to support an effect of SO₂ on CFA leaching of Fe under prestripper conditions as the principal factor in catalyzing oxidative degradation of amines used in CO₂ capture, even though the association with pH depression could still make it significant. At pH = 8, the total leached Fe ions averaged only ≤ 0.2 mg ⋅ L^–1 and ≤ 1.0 mg ⋅ L^–1 from CFA obtained from flue gas cooler inlet and the caustic polisher in the SO₂ loop, respectively. Yet, in an integrated amine solvent SO₂ and CO₂ capturing process as employed at BD3 CCS, the effect is expected to be more significant with respect to amine degradation within the SO₂ capture process.

PPCHEM® 2025, 27(1), 14–32

ABHUG2024 Highlights and Press Release

The annual meeting of ABHUG held on the 3rd to 5th December 2024 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 boiler technology and issues closely related to those in HRSGs. ABHUG2024 attracted 90 participants from Australia, New Zealand, UK and USA. About 45 % of the participants were Users. The next meeting of ABHUG will be in Brisbane in November 2025.

PPCHEM® 2025, 27(1), 34–35

How to Analyze Film-Forming Amines – Analytical Methods and Best Practices

Ronny Wagner

Film-forming amines (FFAs) are increasingly being used instead of conventional conditioning chemicals, as they offer advantages in corrosion protection, especially during operational shutdowns. This article offers an examination of the analytical methods used for quantifying FFAs, highlighting their theoretical basis, practical applications, and inherent challenges. It addresses sampling protocols and monitoring techniques to ensure optimal performance and compatibility within diverse systems. The goal is to provide a comprehensive technical resource for researchers and practitioners aiming to enhance the efficacy of FFAs in industrial applications.

PPCHEM® 2025, 27(1), 38–42

2024’s Scientific and Technical Contributions

PPCHEM® 2025, 27(1), 48–56