Abstract: A turbomachine compressor including variable-pitch vanes, each including an airfoil connected via a plate of circular outline to a pivot guided to pivot in an orifice in a casing, the plate including an air feed duct including one end for communication with a passage formed in the casing when the vane is in a first position, so as to inject air into the annulus of the compressor upstream from the vane, and to be closed by the casing when the vane is in a second position.

Abstract: A turbomachine compressor including variable-pitch vanes, each including an airfoil connected via a plate of circular outline to a pivot guided to pivot in an orifice in a casing, the plate including an air feed duct including one end for communication with a passage formed in the casing when the vane is in a first position, so as to inject air into the annulus of the compressor upstream from the vane, and to be closed by the casing when the vane is in a second position.

Abstract: A gas turbine engine impeller having a plurality of blades attached to a rotor disk and an integral, annular collar defining openings through which the blades extend which acts as a platform extending between the adjacent blades. The annular collar is formed as an integral, annular structure and may be formed from a composite material, or other material which is resistant to high temperatures and high centrifugal forces. The annular collar defines a plurality of openings to accommodate the blade portion of the plurality of blades and to enable the blades to extend radially outwardly from the collar. The openings may be formed in the annular collar when the collar itself is formed, or may be machined therein after the collar has been fabricated.

Abstract: A sulfur dioxide containing gas is purified by successive contact with an ammonia solution and then a dilute ammonium sulfite solution; the latter solution is regenerated by electrodialysis while the ammonia solution, after SO.sub.2 absorption, is vaporized in order to recover ammonia and sulfur dioxide.

Abstract: Sulfur dioxide and ammonia remaining in waste-gas after partial purification thereof, for example by means of ammonia or ammonium sulfite solutions, are withdrawn from said gas by washing with a diluted aqueous solution of ammonium sulfate; the resulting ammonium sulfite containing solution is oxidized thereafter either by means of air or in an electrochemical cell.