For makeup water production in Mannheim Power Station two makeup water treatment plants with integrated reverse osmosis are operated. The older system was com-missioned in 1982 and the newer system was commissioned in 1996. These plants produce makeup water with electric conduc-tivities below 0.2 µS · cm-1 (at 25 °C). The production varies be-tween 75 m3 · h-1 and occasionally even 350 m3 · h-1. For both systems, the raw water is the Rhine River bank filtrate. The overall raw water quality is very good. The level of organics is low with an average TOC below 1 mg · L-1.
Besides a description of the treatment technique, the paper gives a short overview of the different types of reverse os-mosis membranes which have been used in both plants since the beginning of operation until today, and the operat-ing experience that has been made with these mem-branes so far. In addition, there is a short description of a problem with a catalytic ion exchanger in one of the plants.
Copper deposits have frequently been observed in power station superheater tubing. Deposit density measurements were made on superheater specimens from a number of boilers of varying drum pressure, with results ranging from less than 0.1 to 215 g · m-2 (< 0.01 to < 20 g/ft2). The heavi-est deposition was found in the primary section of the super-heater. Microstructural observation indicates that the depo-sition is crystalline in form, consistent with a deposition mechanism from steam on an atomic growth basis, rather than with physical transport of solid particulates. Microanaly-sis demonstrated that the surface of some copper deposits were in oxide form, whereas others were metallic; the oxida-tion state of copper likely has significance regarding the extent of transport of superheater copper deposits to the high pres-sure turbine.
PowerPlant Chemistry 2003, 5 (2)
Ladislav Bursik and Albert Bursik
Inhibited Hydrofluoric Acid - an Effective Chemical Cleaning Solvent
Inhibited hydrofluoric acid has been used in Europe for 35 years for the preoperational and operational chemical cleaning of water- and steam-touched surfaces of steam generators and cycle components. The scientific studies on the dissolu-tion of iron oxides in different acids were begun already in the 1950s; the most significant results, especially for hydrofluoric acid, were achieved in the 1960s.
Chemical cleaning with hydrofluoric acid has proven very successful in combination with the open circuit technique for super-critical once-through boilers. The advantages of the OC technique together with inhibited hydrofluoric acid are the fast dissolution of iron oxides, short application time, low temperatures (50 °C - 80 °C), and the relatively easy han-dling of wastewater.
The OC technique combined with the use of inhibited hydro-fluoric acid is also used for parts of drum-type boilers and heat recovery steam generators.
PowerPlant Chemistry 2003, 5 (2)
Luda Nasri, Paul Leinonen, Frank V. Puzzuoli, and Dev Swami
OPG Operational Experience with Stator Conductor Bar Fouling
Over the last three years, Ontario Power Generation (OPG) Pickering Nuclear has experienced fouling of the stator con-ductor bar cooling water channels on two units. To address the associated stator bar temperature rises, chemical cleaning was undertaken three times on one unit and once on the other.
These events were the subject of two formal investigations and a single rigorous chemistry assessment. The investiga-tions were conducted using a formalized root-cause protocol.
The assessment involved a system chemistry review over a 10-year period and a critical evaluation of dissolved oxygen control.
This paper describes:
the internal investigations undertaken by OPG to better understand and resolve the problem,
OPG's cleaning strategy and different cleaning options performed on affected units,
the remedial actions undertaken by OPG, and
The interim actions following the final post-cleaning inspections.
PowerPlant Chemistry 2003, 5 (2)
EPRI Publishes Revision 1 of the Cycle Chemistry Guidelines for Fossil Plants: All-Volatile Treatment
This contribution is a short review of the Revision 1 of the Cycle Chemistry Guidelines for Fossil Plants: All-Volatile Treatment, which was published in November 2002. This Revi-sion is evaluated as a very important guide for all fossil utilities operating units on all-volatile treatment. Some of the attachments to the revision are also valuable for operators using other cycle chemistry treatments.
In publishing this Revision, EPRI has clearly demonstrated its leadership in the field of fossil plant cycle chemistry and chemistry of water and steam in general.
PowerPlant Chemistry 2003, 5 (2)
Steam Turbines - Steam Purity - A New Technical Specification Issued by the IEC
This paper is a short review of the IEC technical specifica-tion IEC/TS 61370, Steam Turbines - Steam Purity issued in June 2002. The review focuses on a comparison between the new technical specification and the classic EPRI and VGB plant cycle chemistry guidelines.
Inhibierte Flusssäure wird in Europa seit 35 Jahren für die Beizung (chemische Reinigung vor Inbetriebnahme) und chemische Reinigung des Wasser-Dampf-Kreislaufs und der Anlagenteile verwendet. Die wissenschaftlichen Untersu-chungen zur Löslichkeit von Eisenoxiden in verschiedenen Säuren wurden bereits in den 50ger Jahren durchgeführt, die wichtigsten Ergebnisse, insbesondere für die Fluss-säure, wurden in den 60ger Jahren erzielt.
Die Beizung und chemische Reinigung von überkritischen Zwangsdurchlaufkesseln mit Flusssäure haben sich - in Kombi-nation mit dem Open-Circuit-Verfahren (OC-Verfah-ren) - als sehr erfolgreich erwiesen. Die Vorteile liegen in der schnellen Auflösung von Eisenoxiden, kurzer Anwen-dungs-zeit, niedrigen Temperaturen (50 °C - 80 °C) und der relativ einfachen Behandlung des Abwassers.
Das OC-Verfahren mit inhibierter Flusssäure wird auch für die Beizung bzw. chemische Reinigung von Kombianlagen (Abhitzekesseln) eingesetzt.
PowerPlant Chemistry 2003, 5 (2)
Hans Blöchl, Norbert Staub und Joachim Fahlke
20 Years of Reverse Osmosis at Grosskraftwerk Mannheim - Operating Experience
In der Grosskraftwerk Mannheim AG wird das benötigte Zu-satzwasser in zwei Aufbereitungsanlagen mit integrierter Umkehrosmose erzeugt. Die ältere Anlage wurde im Jahre 1982 und die neuere Anlage im Jahre 1996 in Betrieb ge-nommen. Beide Anlagen produzieren Zusatzwasser mit ei-ner elektrischen Leitfähigkeit von kleiner 0,2 µS/cm. Die stündlichen Erzeugungsmengen schwanken zwischen 75 m3 · h-1 und manchmal bis zu
350 m3 · h-1.
Für beide Anlagen wird Uferfiltrat als Rohwasser verwendet. Die Wasserqualität ist insgesamt sehr gut, der mittlere TOC Gehalt liegt unterhalb von 1 mg · L-1.
Neben der Beschreibung der Verfahrenstechnik wird, von der Inbetriebnahme bis heute, im folgenden über Betriebs-erfahrungen mit den verschiedenen Membrantypen berich-tet. Darüber hinaus wird ein Problem beschrieben, das wir mit dem katalytischen Ionenaustauscher in einer der beiden Anlagen hatten.
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