Abstract: An impeller for a centrifugal pump for pumping fluid containing solid particles includes: a rear side wall; a front side wall; a plurality of vanes located between the rear side wall and the front side wall, each vane having an outer edge and a vane width in an axial direction of the impeller. At least one of a periphery of the rear side wall or a periphery of the front side wall projects by a radial distance beyond the outer edges of the vanes, the radial distance being at least 0.5 times the vane width.

Abstract: A pump varies output flow. For all cross-sections, which are vertical to the axis of rotation between axial outer positions for the cross-sectional areas of flow at the periphery of the impeller, the inner wall of the pump housing forms approximately circular profiles. The approximately circular profiles are mainly concentric and have a continuously increasing radius from one toward the other one of the axial outer positions. A tongue, which truncates the outlet or diffuser of the pump from an annulus of the pump housing, does not contact the circular profiles between the axial outer positions.

Abstract: An impeller for a centrifugal pump for pumping fluid containing solid particles includes: a rear side wall; a front side wall; a plurality of vanes located between the rear side wall and the front side wall, each vane having an outer edge and a vane width in an axial direction of the impeller. At least one of a periphery of the rear side wall or a periphery of the front side wall projects by a radial distance beyond the outer edges of the vanes, the radial distance being at least 0.5 times the vane width.

Abstract: Boost system and method for dual gradient drilling where a marine riser (1) has a mud return line (14) connected at a first connection position (18) below the lowest foreseeable mud level (12) in the marine riser (1), and where a mud return pump (16) is connected to the mud return line (14), and where a recirculation line (20) that has a recirculation pump (22), is connected to the marine riser (1) at a second connection position (24) below the lowest foreseeable mud level (12) in the marine riser (1), and at a third connection position (26) on the marine riser (1) below said second connection position (24).

Abstract: Boost system and method for dual gradient drilling where a marine riser (1) has a mud return line (14) connected at a first connection position (18) below the lowest foreseeable mud level (12) in the marine riser (1), and where a mud return pump (16) is connected to the mud return line (14), and where a recirculation line (20) that has a recirculation pump (22), is connected to the marine riser (1) at a second connection position (24) below the lowest foreseeable mud level (12) in the marine riser (1), and at a third connection position (26) on the marine riser (1) below said second connection position (24).

Abstract: A pump varies output flow. For all cross-sections, which are vertical to the axis of rotation between axial outer positions for the cross-sectional areas of flow at the periphery of the impeller, the inner wall of the pump housing forms approximately circular profiles. The approximately circular profiles are mainly concentric and have a continuously increasing radius from one toward the other one of the axial outer positions. A tongue, which truncates the outlet or diffuser of the pump from an annulus of the pump housing, does not contact the circular profiles between the axial outer positions.

Abstract: An outer rotor of a progressive cavity pump includes at least one inner helical rotor with Z external thread starts and at least one adapted outer rotor with a helical cavity with Z+1 internal thread starts. The at least one outer rotor is assembled from several concentric rotor inserts axially following closely one after another, with helical cavities and Z+1 internal thread starts. Each rotor insert is closely surrounded by and concentrically fixed in a common rigid rotor sleeve. There is detachably connected to the rotor sleeve at least one removable end piece with a principally concentric hollow axially extending through it. The through hollow of the end piece or end pieces forms a gradual transition between a principally circular cross section furthest out and a cross section adapted to the helical cavities of the rotor inserts nearest to them.

Abstract: A progressing cavity pump adapted for pumping of compressible fluids may include an inner rotor having a number of thread-starts together with an adapted stator or outer rotor provided with one extra thread-start. A number of closed pump cavities are formed which are moved, during fluid conveyance, from the inlet side of the pump to the outlet side of the pump, at which position they become open outlet cavities exposed to the fluid pressure in a downstream pipeline. At least one passage is disposed between the outlet side and the closed pump cavity defined closest to the outlet side. The passage is structured for intentional fluid back-flow from the outlet side in a measured and approximately constant volume.

Abstract: A progressive cavity pump includes at least one inner rotor with Z external threads and at least one outer rotor with Z+1 internal threads. The outer rotor has radial bearings at both ends, whereas the inner rotor has a radial bearing only on one side, preferably the inlet side. There is arranged, on the same side as the bearing of the inner rotor, a conventional gear, for example a wheel gear, for maintaining a stable ratio between the rotational speeds of the inner and outer rotors exactly equal to (Z+1)/Z.

Abstract: A progressing cavity pump comprises at least an inner pump rotor enclosed by at least an outer pump rotor so as to collectively form one or more, in principle, separate pump cavities which, according to known geometric principles, will be moved axially through the pump upon bringing the rotors into coordinated rotation. At least two pump sections are disposed therein, each of which comprises one outer pump rotor and one adapted inner pump rotor. The outer pump rotors of all pump sections are fixedly supported and arranged along the same axis, wherein all the inner rotors are supported in fixed positions relative to a pump casing of the pump. The outer rotors of all pump sections are driven by the same motor via at least one differential arranged to allow each pump section to rotate at a mutually different rotational speed.

Abstract: The invention relates to a progressive cavity pump comprising at least one inner rotor (18) with Z external threads and at least one adapted outer rotor with Z+1 internal threads, characterized by the outer rotor having radial bearings at both ends, whereas the inner rotor has a radial bearing (11) only on one side, preferably the inlet side, and there being arranged, on the same side as the bearing of the inner rotor, a conventional gear, for example a wheel gear (33 etc.), maintaining a stable ratio between the rotational speeds of the inner and outer rotors exactly equal to (Z+1)/Z.

Abstract: An outer rotor of a progressive cavity pump comprising at least one inner helical rotor with Z external thread starts and at least one adapted outer rotor with a helical cavity with Z+1 internal thread starts, characterized in that at least an outer rotor (1, 3) is assembled from several concentric rotor inserts (109-113, 307-311) following closely one after another axially, with helical cavities and Z+1 internal thread starts, each rotor insert being closely surrounded by and concentrically fixed in a common rigid rotor sleeve (101, 301), and there being detachably connected to the rotor sleeve at least one removable end piece (102, 302, 303) with a principally concentric hollow extending through it axially, and that the through hollow of the end piece (102) or end pieces (302, 303) forms a gradual transition (106, 306, 312) between a principally circular cross section furthest out (135, 313, 314) and a cross section adapted to the helical cavities of the rotor inserts nearest to them (109, 307, 311).

Abstract: A progressing cavity pump adapted for pumping of compressible fluids, comprising an inner rotor (1) having a number of thread-starts (Z) together with an adapted stator or outer rotor (2) provided with one extra thread-start (Z+1), wherein a number of, in principle closed pump cavities (6) are formed which are moved, during fluid conveyance, from the inlet side (A) of the pump to the outlet side (B) of the pump, at which position they become open outlet cavities (6c) exposed to the fluid pressure in a downstream pipeline, and wherein at least one passage is disposed between the outlet side (B) and the, in principle, closed pump cavity (6b) defined closest to the outlet side (B), wherein said passage is structured for intentional fluid back-flow from the outlet side (B) in a measured and approximately constant volume.

Abstract: A progressing cavity pump comprises at least an inner pump rotor enclosed by at least an outer pump rotor so as to collectively form one or more, in principle, separate pump cavities which, according to known geometric principles, will be moved axially through the pump upon bringing the rotors into coordinated rotation. At least two pump sections are disposed therein, each of which comprises one outer pump rotor and one adapted inner pump rotor. The outer pump rotors of all pump sections are fixedly supported and arranged along the same axis, wherein all the inner rotors are supported in fixed positions relative to a pump casing of the pump. The outer rotors of all pump sections are driven by the same motor via at least one differential arranged to allow each pump section to rotate at a mutually different rotational speed.