Toma De Agua De Mar

International Symposium on Outfall Systems, May 15-18, 2011, Mar del Plata, Argentina

SEAWATER INTAKE STRUCTURES
E. Pita (*), Isidro Sierra (**) ∗ Eloy Pita, Civil Engineer and General Manager, Ingeniería Creativa Pita, S.L. (INCREA), Calle Buganvilla 6, p1, 1ºA. Madrid 28036-Spain (E-mail: epita@increa.eu; www.increa.eu) ∗ Isidro Sierra, Mechanical Engineer and General Manager PPA&KRAH,Camino Playabarri nº 1. 48950-Luchana-Erandio, Biscay, Spain (E-mail: isidro.sierra@ppa.es; www.ppakrah.com) Abstract The seawater intake structures are used, above all, in desalination plants, fish farms and refrigeration circuits for industries and combined cycle gas turbine (CCGT) power stations. The function of these structures is to collect water of specific characteristics for the requiredfunction, and the design thereof must be carried out so that the negative impacts on the environment may be minimised to the upmost and with adequate characteristics relating to temperature, suspended solids, etc. In this paper we shall focus upon open intake structures on the sea bed. These structures are elements which are, generally speaking, constructed from reinforced concrete or plastic elements(GRP) covered with concrete, the function of which is the collection of the seawater, which is then transported by means of underwater pipelines to the pump stations, which are located on land. After the types of intake structures have been defined, the principal design parameters shall be set out, and finally, we will describe the most recent experiences in which INCREA has participated asdesigner and PPA as manufacturer and installer. Keywords Intake structure, collection, desalination plant, intake, outfall, refrigeration, fish farm, intake tower.

INTRODUCTION With the recent increase in the construction of seawater desalination plants and of thermal power stations that require refrigeration circuits, as well as other installations that require seawater intake systems, both thenumber of designs as well as the size of the collection structures have increased. In respect of this increase, of significant influence has been the possibility of using pipelines of greater diameter, that allow for the water intake by means of a pipe with greater volume capacity, and which logically, require intake towers of greater magnitude. The function of these structures is to collect waterwith a temperature and certain quality characteristics which are suitable for the required function, minimising the environmental impact to the surroundings thereof. Such impacts shall depend upon the type of plant, as the requirements for a combined cycle gas turbine (CCGT) power station, which uses the collected water in order to refrigerate the circuit, shall not be the same as those in respect ofa seawater desalination plant, the purpose of which is essentially human consumption. Accordingly, the most habitual types of intake structures shall be summarised, (focusing upon open intake structures on the sea bed), the parameters for the design thereof and the most recent experiences concerning the design and construction of the intake structures, in respect of which the increase of thesizes thereof is able to be verified, which duly creates the need for more sophisticated structures. TYPES OF STRUCTURES

International Symposium on Outfall Systems, May 15-18, 2011, Mar del Plata, Argentina

The principal types of seawater intake structures are as follows: Wells Water is extracted from the phreatic water-table level, at the coast. The well intakes have the advantage that thewater is of higher quality, and accordingly it is a good option for desalination plants. Through the wells, a pump sucks the water, which is then subjected to different filtering systems so as to separate the sand and other impurities. The disadvantage of this type of seawater intake structure is that the hydraulic capacity will often be reduced by reason of the silting thereof (clogging with fine...