Abstract: A gas seal assembly includes a pair of mutually rotatable sealing members, each of which has a front face adjacent a gap between the two members which constitutes a leakage path through the seal assembly. The two sealing member are urged, in use, in a direction to close the gap and a gas bleed arrangement is provided for allowing gas from a high pressure side of the seal to bleed into the gap so as to apply a force tending to separate the members. The gas bleed arrangement includes a bore extending between the front face and a rear face of one of the sealing members, a generally radial groove formed in the rear face of the sealing member and a plate overlying the rear face to cover the groove and thereby define between the rear face of the sealing member and the plate a bleed passage connecting the bore to the high pressure side of the seal.

Abstract: A tandem gas seal assembly is described for sealing between the rotor and the casing of a rotary machine. The assembly comprises two sealing stages 10, 12 mounted axially adjacent to one another on the machine rotor. In the invention, wherein the two stages 10 and 12 are totally separable from one another and each is capable of functioning as a seal when separated from the other.

Abstract: A rotary electric machine is disclosed having stator windings and a rotor incorporating permanent magnets distributed about the axis of the rotor to create a magnetic field having circumferentially alternating north and south poles. In the invention, the principal structural member is an external sleeve, this providing resistance to bending and to centrifugally induced stresses due to rotation. The direction of polarization of the permanent magnets 214 is such that the parts of the magnetic circuits that lie within the outer circumference of the rotor pass predominantly through the bodies of the permanent magnets 214, thereby avoiding the need for a central ferromagnetic core to complete the magnetic circuit of the magnets.

Abstract: A multi-stage compressor comprises a variable speed electrically driven rotodynamic compressor stage connected in series with and upstream of a water lubricated screw compressor stage and an intercooler arranged between the two compressors to reduce the temperature of gas entering the screw compressor stage. In the invention, the intercooler is a water spray intercooler, the water supply of which is shared with that of the water lubricated screw compressor.

Abstract: A rotary electric machine is disclosed having stator windings and a rotor incorporating permanent magnets distributed about the axis of the rotor to create a magnetic field having circumferentially alternating north and south poles. In the invention, the principal structural member is an external sleeve, this providing resistance to bending and to centrifugally induced stresses due to rotation. The direction of polarization of the permanent magnets 214 is such that the parts of the magnetic circuits that lie within the outer circumference of the rotor pass predominantly through the bodies of the permanent magnets 214, thereby avoiding the need for a central ferromagnetic core to complete the magnetic circuit of the magnets.

Abstract: A tandem gas seal assembly is described for sealing between the rotor and the casing of a rotary machine. The assembly comprises two sealing stages 10, 12 mounted axially adjacent to one another on the machine rotor. In the invention, wherein the two stages 10 and 12 are totally separable from one another and each is capable of functioning as a seal when separated from the other.