Water chemistry plays important roles in safe and reliable plant operation which are very critical for future power rate increases as well as aging plant management. Water chemistry control is required to satisfy the need for improved integrity of target materials, and at the same time it must be optimal for all materials and systems in a plant. Optimal water chemistry can be maintained by expert engineers who are knowledgeable about plant water chemistry, who have sufficient experience with plant operation, and whose knowledge is based on fundamental technologies. One of the latest subjects in the field of water chemistry is achieving suitable technical transfers, in which the achievements and experience with plant water chemistry accumulated by experts are successfully transferred to the next generation of engineers. For this purpose, documents on experience with water chemistry are being compiled as the guidance for water chemistry control and water chemistry standards, e.g., standards for chemical analysis procedures and guidance for water chemistry control procedures. This paper introduces the latest activities in Japan in establishing water chemistry guidance involving water chemistry standards, guidance documents and their supporting documents.

This paper deals with the burning of heavy residual fuel oil containing ~ 3.5 % sulfur and low vanadium (~ 40 ppm) under conditions prevalent in heating boilers to assess the use of fuel chemical additives on the formation of noxious and corrosive products of combustion. Saline Water Conversion Corporation's (SWCC's) boilers that are attached to the dual-purpose desalination/power plants in the Western Province of Saudi Arabia using heavy residual fuel oil are reported to have chronic corrosion problems causing unscheduled shutdown and frequent replacement of equipment resulting in high maintenance costs and loss of production besides creating environmental problems. The effectiveness of fuel chemical additives in controlling boiler internal corrosion and reducing the emission of hazardous gases was tested. Three magnesium-based compounds (A, B & E), one organic-based compound (C), and another hydrocarbon-based non-metallic (D) additive were selected based on the literature provided by the companies. Evaluation was carried out by online monitoring of flue gas parameters such as SO₂, SO₃, CO₂ and NO_x, acid dew point, rates of acid build-up and quantitative determination of boiler soots. The effects of the additives on the boiler performance were also monitored by evaluating boiler load, efficiency, flue gas outlet temperature, opacity, fuel and steam flows. The boiler's internals were inspected before and after the testing of each additive.

The results of the three MgO-based slurries tested were quite comparable. The organically based Mg-compound and the non-metallic additive showed lower efficiency in the cold end of the boiler. Though there was a slight decrease in the performance of the additives as the dose rates decreased, the optimum dose rates determined were 150–160 mg · kg^-1 for chemical A, 200–250 mg · kg^-1 for chemical B, 180–190 mg · kg^-1 for chemical C, 500 mg · kg^-1 for chemical D and 250 mg · kg^-1 for chemical E to be effective. Based on the studies, chemical A was found to be the most effective and economical among the five chemicals tested.

Studies were conducted with the aim of providing answers to important questions concerning the use of film-forming amines in steam generators. Tests were carried out in test steam generators under controlled conditions to study the three following application areas: the influence of film-forming amines on boiling behavior and heat transfer, the influence of film-forming amines on oxidic protective film formation, and the influence of film-forming amines on critical operating conditions. In the experiments water treatment with trisodium phosphate (which is normally used with shell boilers) was compared with treatment with film-forming amines. In all three areas the treatment with film-forming amines achieved comparable or better results than the treatment with trisodium phosphate.

Many power plants with designs of condensate polishers that date to the 1960s and early 70s were originally provided with a pre-filtration stage. In many cases these pre-filters are no longer used because of the effort required to keep them working [1]. Thus, the use of the pre-filters ahead of these early polishing plants at fossil units has largely ceased. Advances in filtration technology in recent years have made the deployment of filtration in condensate systems very effective in terms of both performance and cost. The use of disposable filter cartridges to control the transport of solids, especially during the startup phase when the suspended solids content is at its highest, has proven to be a very effective upgrade with a quick payback for the power plants. These filtration systems using cartridges engineered for optimum solids holding capacity, high flow rate, low pressure loss and compact size are highly efficient and cost effective. The paper discusses several case studies on the use of the disposable filter cartridges, made using a proprietary pleat design that gives the filter cartridge an exceptionally high flow capacity and contamination holding capacity while providing 99.98 % particulate removal efficiency at the rated µm size. Experience with filtration system installations at several fossil power plants are discussed including the upgrade of a 1 000 MW power plant in northern Italy that was using back-washable metal filter cartridges with cellulose-based filter-aid and two US power plants that utilize the filtration system during the critical startup phase.

As every year, the January issue closes with abstracts of all the articles published in this journal in the first half of the previous year. Back issues of our journal are – with few exceptions – still available and that you can receive PDF files of all articles by e-mail. The order forms may be downloaded from our homepage.