Xylem

The invention relates to a pump for pumping liquid comprising solid matter. The pump comprises a hydraulic unit that comprises an impeller seat (5) and an open impeller (7), wherein the open impeller (7) has at least one spirally swept blade (12) having a leading edge (13), a trailing edge and a lower edge (15), wherein the impeller seat (5) comprises a guide pin (22) extending radially inwards, wherein the leading edge (13) of the blade (12) is configured to cooperate with the guide pin (22) of the impeller seat (5) during operation of the pump (1), and wherein an axially extending centre axis (A) of the impeller seat (5) is located at a relative radius R* equal to 0 and a circular intersection (20) between the inlet wall (19) and the upper surface (21) of the impeller seat (5) is located at a relative radius R* equal to 1. The pump is characterized in that a shearing angle (α) between a projected tangent (26) to the leading edge (23) of the guide pin (22) and a projected tangent (27) to the intersection between the leading edge (13) of the blade (12) and the pressure side (17) of the blade (12), between a first relative radius R1 equal to 0,35 and a second relative radius R2 equal to 0,95, is alternating between a major-value range and a minor-value range upon rotation of the impeller (7) in relation to the impeller seat (5), the minor-value range being limited by a lower value that is equal to or more than -30 degrees and an upper value that is equal to or less than 30 degrees and the major-value range being limited by a lower value that is equal to or more than 70 degrees and an upper value that is equal to or less than 100 degrees, wherein transition from the major-value range to the minor-value range occur at least two times.

The invention relates to a submersible semi-axial centrifugal pump (1) for installation in a column (2), and comprises an outer pump housing (7) and an inner pump core arrangement (14). The pump core arrangement comprises a drive unit (16), a semi-axial open centrifugal impeller (20) and a plurality of guide vanes (15) extending between and connecting the pump housing (7) and the drive unit (16), wherein the impeller (20) comprises a hub (28) and at least two spirally swept blades (29), wherein the hub (28) is essentially cone-shaped tapering towards the inlet (12) of the pump housing (7). Each blade (29) comprises a leading edge (31), a trailing edge (32) and a lower edge (33). The outer pump housing (7) comprises a diffuser (9), connected to the stationary drive unit (16) via the radially extending guide vanes (15), and an inlet funnel (8), fixedly connected to the diffuser (9), wherein the semi-axial centrifugal pump (1) comprises a pump housing liner (38), located between the outer pump housing (7) and the lower edge (33) of the impeller (20), wherein the pump housing liner (38) is displaceable in the axial direction in relation to the outer pump housing (7) in order to adjust a radial gap (39) between the pump housing liner (38) and the lower edge (33) of the impeller (20).

The invention relates to a submersible semi-axial centrifugal pump (1) for installation in a column (2), and comprises an outer pump housing (7) and an inner pump core arrangement (14). The pump core arrangement comprises a drive unit (16), a semi-axial open centrifugal impeller (20) and a plurality of guide vanes (15) extending between and connecting the pump housing (7) and the drive unit (16), wherein the impeller (20) comprises a hub (28) and at least two spirally swept blades (29), wherein the hub (28) is essentially cone-shaped tapering towards the inlet (12) of the pump housing (7). Each blade (29) comprises a leading edge (31), a trailing edge (32) and a lower edge (33). The leading edge (31) of each blade (29) is swept backwards from an inner end (36) located at the hub (28) towards an outer end (37) located at the inner surface (11) of the pump housing (7), wherein a centre axis (A) of the impeller (20) is located at a relative radius R* equal to 0 and the outer end (37) of the leading edge (31) of each blade (29) of the impeller (20) is located at a relative radius R* equal to 1, and wherein a sweep angle (α) of the leading edge (31) is in the range 32 - 45 degrees at a first relative radius R*1 equal to 0,5, and in the range 47 - 60 degrees at a second relative radius R*2 equal to 0,95, and is continuously increasing from the first relative radius R*1 to the second relative radius R*2.

The present invention relates to a centrifugal pump (1) comprising a drive unit (2) having an electric motor (3) and a drive shaft (4), a hydraulic unit (5) connected to the drive unit (2). The centrifugal pump further comprises an impeller (10) connected to the drive shaft (4) and located in a volute (9). The centrifugal pump (1) further comprises a sealing arrangement (13-14) connected to the housing (8) and configured for sealing between the impeller (10) and the housing (8). The centrifugal pump is characterized in that the seal member (13) is displaceable in the radial direction in relation to the clamping member (14), wherein the seal member (13) comprises a first engagement means (15) and the clamping member (14) comprises a second engagement means (16) configured to cooperate with the first engagement means (15) of the seal member (13), and wherein the sealing arrangement (13-14) has a play in the rotational direction between the first engagement means (15) and the second engagement means (16) whereby the seal member (13) is displaceable in the circumferential direction in relation to the clamping member (14) an angle α that is equal to or less than ± 3 degrees.

The invention relates to a method for monitoring and controlling the operation of a liquid flow generator (1) configured for operation in a tank (18) housing in a liquid comprising solid matter. The flow generator (1) comprises a propeller (3) and a main body (7) having a drive unit (4), wherein a control unit (4) is operatively connected to the flow generator (1) in order to monitor and control the operation of the flow generator (1), the method comprises the steps of: a) driving the propeller (3) in a normal direction of rotation, wherein the liquid flow is directed from an upstream side of the propeller (3) towards a downstream side of the propeller (3), wherein the main body (7) is located at the upstream side of the propeller (3), b) performing a cleaning sequence in response to a main body cleaning signal, wherein the cleaning sequence comprises the steps of: i) stopping the propeller (3) from rotating in the normal direction of rotation, ii) driving the propeller (3) in a reverse direction of rotation, wherein the liquid flow is directed from the downstream side of the propeller (3) towards the upstream side of the propeller (3) and along the main body (7) in order to remove any solid matter accumulated on the main body (7), and iii) stopping the propeller (3) from rotating in the reverse direction of rotation, c) resume driving of the propeller (3) in the normal direction of rotation.

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