Water consumption in Wärtsilä power plants is low since the cooling is normally via air-cooled radiators. In some rare cases cooling towers may be used and this will naturally increase the water consumption, but even in this kind of installation water consumption is relatively low. In the European Commission’s “Reference Document on Best Available techniques for Large Combustion Plants” the water consumption of an engine power plant has been estimated. According to this document “an engine driven power plant usually preserves its water”.
However, consumption in a Wärtsilä power plant is even lower than the document states. For example, for a 130 MWe power plant, water consumption is around 150 m3/h using a cooling tower, whereas in the document it has been estimated to be 220 m3/h. As a comparison, the document gives a value of 500 m3/h for a steam turbine plant of the same size. In the case of radiator cooling, the water consumption is negligible in comparison to these figures.
The estimated total water consumption, including all the water needed in the plant’s operations, is around 9 l/MWh for a Wärtsilä HFO plant, and around 2.7 l/MWh for a LFO & gas plant. These values are based on the assumption that cooling is via radiators, which is the standard solution.
In HFO plants, water is consumed by the process water, boiler water and sanitary water. The process water consumption includes water used by the fuel oil and lube oil separators, turbo washing, the oily water treatment system, and workshop operations. Some minor amounts may also be used in engine cooling and by evaporation. Another consumer group are boilers. In HFO plants own consumption boilers are used to produce steam for plant operation purposes. The boilers consume water in the form of make-up water, and also in cooling blow-down from the boiler. The third and smallest consumer is sanitary use.
As opposed to HFO plants, in LFO & gas plants the majority of the water is consumed by the sanitary system. The process water consumption in these plants mainly consists of that used in workshop operations. As with HFO plants, engine cooling may also consume some minor amounts through leakages and evaporation. However, cooling is not the main factor in the water consumption of either type of plant, unlike in many other power plant types.
Wärtsilä power plants are well known for their excellent performance, even in difficult conditions, such as high ambient temperatures or altitudes. The performance of the plant remains high regardless of whether the plant is installed in tropical or arctic conditions, or if the plant is located at high altitude. Moreover, the installation’s location has no significant effect on the plant’s water consumption. With gas turbine installations things are different. Gas turbine performance is normally given in ISO conditions, meaning a dry bulb temperature of 15 °C, a relative humidity of 60%, and an atmospheric pressure of 1 bar (sea level). However, most gas turbine installations are not operating in such conditions. And the performance of a gas turbine decreases the more actual conditions differ from these norms.
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