| CPC F04D 25/06 (2013.01) [F04D 29/056 (2013.01); F04D 29/4213 (2013.01); F04D 29/5826 (2013.01); F04D 17/125 (2013.01); F04D 29/444 (2013.01)] | 15 Claims |

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1. A multi-stage electric centrifugal compressor, comprising:
a rotational shaft;
a low-pressure-stage impeller disposed at one end of the rotational shaft;
a high-pressure-stage impeller disposed at another end of the rotational shaft;
a high-pressure-stage housing accommodating the high-pressure-stage impeller;
an electric motor configured to drive the low-pressure-stage impeller and the high-pressure-stage impeller; and
a connecting pipe for supplying a compressed gas compressed by the low-pressure-stage impeller to the high-pressure-stage housing,
wherein the high-pressure-stage housing has a high-pressure-stage inlet opening that opens in a first direction intersecting an axis of the rotational shaft,
wherein the connecting pipe includes a high-pressure-stage-side connection portion connected to the high-pressure-stage inlet opening, and
wherein a flow path cross-section perpendicular to an extending direction of an axis of the high-pressure-stage-side connection portion has a longitudinal direction along a direction perpendicular to the axis of the rotational shaft, and includes concavely curved portions formed at both ends in the longitudinal direction of the flow path cross-section of the high-pressure-stage-side connection portion.
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