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A measure of success in the fight against corrosion: dissolved impurities in water and steam con cause damaging corrosion and deposition in modern power plants operating at increasingly high temperatures and pressures. To control these impurities, it is first necessary to measure them accurately.

Article Excerpt
In countries such as India and China, which are still growing despite the economic slowdown, power generation or, to be more precise, the 'quality' of power generation matters a lot.

[ILLUSTRATION OMITTED]

One way to improve power generation would be to increase generation capacity. Another would be to save power by operating power plants more efficiently, reducing outages and loss of capacity. The latter strategy sounds more economical, as the cost of maintaining the health of a power plant is far lower than that of continually adding capacity.

Corrosion and deposition play a major role in destabilizing power plants, reducing both power generation efficiency, leading to reduced output, and the effective life of a power plant.

Maintaining water and steam quality at ultra-pure levels is one of the best ways to reduce the effects of corrosion and deposition. A water quality management system is therefore vital for any power plant running on steam.

In such a plant, impurities such as dissolved oxygen, silica, phosphate, sodium, chlorides and many others, slowly eat into the boiler tubes/superheaters and, more importantly, the turbines. These impurities ultimately result in corrosion and deposition, which can lead to turbine failures and boiler shutdowns, and, in extreme cases, permanent damage to equipment. The cost of unplanned shutdowns can be high. In fact, more than 50 per cent of unplanned shutdowns are due to inadequate analysis and control of impurities, and the corrosion and deposition resulting from it.

Corrosion, if not monitored properly, can result in a loss in turbine efficiency of 10 per cent. This means a recurring loss of 10 per cent of revenue. If not enough attention is paid to the corrosion/deposition problem, this loss can be compounded by damages to the turbine or even turbine failure.

Corrosion and deposition have similar effects to those of cholesterol levels in our bodies. Our cholesterol levels need to be controlled, and to do this a proven, reliable and accurate method of measuring and monitoring cholesterol levels is required. It is the same with deposition and corrosion. More specifically a reliable and accurate method of online analysis is needed. Good online analyzers supported by a well-engineered sample conditioning system is the ideal solution. A sample conditioning system and online analyzer system is called a steam and water analysis system (SWAS). With a well-engineered SWAS, it is possible to monitor various dissolved impurities that damage the turbines and other steam equipment to parts per billion (ppb) levels--continuously and online.

Forbes Marshall is one of the largest manufacturers of SWAS packages. The company's integrated sample conditioning and analysis system includes conditioning equipment and world class online analyzers.

Any good SWAS package depends on expertise in steam engineering as well as control instrumentation. Forbes Marshall can provide this expertise. With an installed base of over 350 SWAS packages, the company has solutions for the most complex steam and water analysis requirements.

WATER QUALITY IMPROVEMENTS

In the power industry, control of water purity is a prerequisite for the safe and efficient operation of the boiler plant. Typically, up to 20 different samples per boiler unit are taken from various...

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