Gas and Steam Power Plant in Trinidad with High Demands on Process Water   

For a 765 megawatt gas and steam power plant in La Brea, Trinidad, to be built by Ferrostaal, the water technology company Berkefeld (Germany), a subsidiary of Veolia Water Solutions & Technologies, is supplying the process water treatment system and part of the wastewater treatment. A combination of various process technologies will be used, in-cluding reverse osmosis with electro-deionisation, in order to ensure compliance with the demands of the energy generation.

A special challenge in this project is the water treatment configuration, in close coopera-tion between the power plant builder and the water technology supplier to optimally suit the local conditions. An important precondition was that the power plant would draw on variable proportions of municipal water and condensate (blow-down) from the cooling towers. Therefore, a storage tank with recirculation and active carbon filtration was planned. This achieves a homogenisation of the different raw waters with different spe-cific ingredients. Furthermore, it removes pollution and ensures effective disinfection. As pre-treatment before the reverse osmosis, a multimedia filter to eliminate solid matter as well as a carbonate removal will be used.

The current ultrapure water production phase is made by reverse osmosis , with electro-deionisation in two trains as a follow-up, each one for 25 m3 of treated water per hour. Additionally, in order to remove possible mineral residues, a mixed bed filter is foreseen. Thus, in compliance with the strict VGB quality demands on the demineralised water, in-cluding with regard to conductivity, sodium and silicate concentration and the content of dissolved organic carbon ("DOC") are continually assured.

The wastewater ensuing from the ultrapure water treatment, such as filter backwashing water and RO concentrate, is treated by means of a settling tank to eliminate any sludge that arises, as well as by subsequent neutralisation.