Abstract: A barrel-type multistage pump with uniformed velocity distribution in an axial direction, on a cross-section of a rotating flow channel, to suppress fluid loss in a last stage, and including: plural stages of centrifugal impellers, covered by an inner casing; diffusers and return channels provided on downstream sides of the centrifugal impellers, to guide the flow of a fluid to a centrifugal impeller in the next stage, and return vanes arranged at respective return channels; a cylindrical outer casing having a suction pipe and a discharge pipe, wherein a cylindrical rotating flow channel connected to a discharge opening is provided between an outer casing and an inner casing, a connecting channel to connect between a rotating flow channel and diffusers.

Abstract: The present invention is to suppress generation of cavitation in an impeller of a pump and disproportion of generation areas thereof by suppressing a secondary flow generated in a bent portion of a pump suction pipe. A pump suction pipe includes: a suction pipe outlet portion that is connected to an impeller suction port of a pump and is arranged in the up-and-down direction; a suction pipe inlet portion that is arranged in the lateral direction; and a suction pipe bent portion that connects the suction pipe outlet portion and the suction pipe inlet portion to each other and changes a flow from the lateral direction to the up-and-down direction. The distance from a reference point to an inner end of the suction pipe bent portion is monotonically increased from the upstream side to the downstream side on a vertical cross-section.

Abstract: A barrel-type multistage pump with uniformed velocity distribution in an axial direction, on a cross-section of a rotating flow channel, to suppress fluid loss in a last stage, and including: plural stages of centrifugal impellers, covered by an inner casing; diffusers and return channels provided on downstream sides of said centrifugal impellers, to guide the flow of a fluid to a centrifugal impeller in the next stage, and return vanes arranged at respective return channels; a cylindrical outer casing having a suction pipe and a discharge pipe, wherein a cylindrical rotating flow channel connected to a discharge opening is provided between an outer casing and an inner casing, a connecting channel to connect between a rotating flow channel and diffusers.

Abstract: A barrel-type multistage pump with uniformed velocity distribution in an axial direction, on a cross-section of a rotating flow channel, to suppress fluid loss in a last stage, and including: plural stages of centrifugal impellers, covered by an inner casing; diffusers and return channels provided on downstream sides of said centrifugal impellers, to guide the flow of a fluid to a centrifugal impeller in the next stage, and return vanes arranged at respective return channels; a cylindrical outer casing having a suction pipe and a discharge pipe, wherein a cylindrical rotating flow channel connected to a discharge opening is provided between an outer casing and an inner casing, a connecting channel to connect between a rotating flow channel and diffusers.

Abstract: The present invention is to suppress generation of cavitation in an impeller of a pump and disproportion of generation areas thereof by suppressing a secondary flow generated in a bent portion of a pump suction pipe. A pump suction pipe includes: a suction pipe outlet portion that is connected to an impeller suction port of a pump and is arranged in the up-and-down direction; a suction pipe inlet portion that is arranged in the lateral direction; and a suction pipe bent portion that connects the suction pipe outlet portion and the suction pipe inlet portion to each other and changes a flow from the lateral direction to the up-and-down direction. The distance from a reference point to an inner end of the suction pipe bent portion is monotonically increased from the upstream side to the downstream side on a vertical cross-section.

Abstract: A barrel-type multistage pump with uniformed velocity distribution in an axial direction, on a cross-section of a rotating flow channel, to suppress fluid loss in a last stage, and including: plural stages of centrifugal impellers, covered by an inner casing; diffusers and return channels provided on downstream sides of said centrifugal impellers, to guide the flow of a fluid to a centrifugal impeller in the next stage, and return vanes arranged at respective return channels; a cylindrical outer casing having a suction pipe and a discharge pipe, wherein a cylindrical rotating flow channel connected to a discharge opening is provided between an outer casing and an inner casing, a connecting channel to connect between a rotating flow channel and diffusers.