The absorber includes a row of sprinklers (5), situated inside a storage tank (4) adapted to receive a hot and concentrated solution, and to project it inside the tank (4) for its dilution, having a heat exchanger (6) of the solution-air or solution-water type, which is external to the storage tank (4) and cools the diluted solution. Each of the sprinklers from the row of sprinklers (5) comprisesnozzles (14) with an oval shape, adapted to spray the solution in the form of a flat sheet (15) with an essentially triangular, fan-type shape, projected in parallel.