Pump unit, pump system, and pump system operation method
A pump unit ( 2, 2 A) is connected to a reservoir tank (T 1 ) where liquid hydrogen and hydrogen gas generated by vaporization of the liquid hydrogen are stored and transfers the liquid hydrogen. The pump unit includes a rotation shaft ( 31 ), a motor (M) causing the shaft to rotate, an impeller ( 41 ) mounted on a front end ( 31 a ) of the shaft, a housing ( 30, 40 ) including a motor chamber ( 36 ) where the motor is accommodated and a pump chamber ( 43 ) where the impeller is accommodated, and a mechanical seal ( 42 ) mounted on the shaft and the housing and configured to seal the motor chamber with respect to the pump chamber. The motor includes a rotor ( 34 ) mounted on the shaft and a stator ( 35 ) that directly faces the rotor in a radial direction of the shaft and causes the rotor to rotate. The hydrogen gas is introduced into the motor chamber.
1 . A pump unit comprising:
a rotation shaft;
a motor configured to cause the rotation shaft to rotate;
an impeller mounted on the rotation shaft;
a housing including a motor chamber housing that defines a motor chamber in which the motor is accommodated and a motor pump chamber housing that defines a pump chamber in which the impeller is accommodated; and
a mechanical seal mounted on the rotation shaft and the housing in an arrangement for sealing the motor chamber with respect to the pump chamber,
wherein
the rotation shaft extends into the motor chamber and into the pump chamber;
the motor includes:
a rotor mounted on the rotation shaft, and
a stator that directly faces the rotor in a radial direction of the rotation shaft and is configured to cause the rotor to rotate;
the motor chamber housing includes:
a motor chamber outer wall that separates the motor chamber from an environment outside the housing, and
a gas introduction port, disposed in the motor chamber outer wall, and configured to allow introduction into the motor chamber of hydrogen gas;
the pump chamber housing includes a pump chamber outer wall that separates the pump chamber from the environment outside the housing;
the housing includes:
a suction port, disposed on a side of the pump chamber outer wall, and configured to allow, during rotation of the impeller, liquid hydrogen to be suctioned into the pump chamber,
a discharge port, disposed on a side of the motor chamber outer wall, and configured to allow the liquid hydrogen to be discharged, and
a guiding flow line configured to guide a discharge flow of the liquid hydrogen from
the pump chamber to the discharge port;
the guiding flow line includes:
a pump chamber guiding flow line that is disposed in the pump chamber outer wall and extends from the pump chamber to a pump chamber guiding flow line termination, and
a motor chamber guiding flow line that is disposed in the motor chamber outer wall and extends from the pump chamber guiding line termination to the discharge port;
the gas introduction port is configured to be connectable to an external gas line capable of extending to hydrogen gas in a reservoir tank; and
the suction port is configured to be connectable to an external suction flow line capable of extending to liquid hydrogen in the reservoir tank.
2 . The pump unit according to claim 1 , wherein the motor chamber guiding flow line is disposed in the motor chamber outer wall in such a configuration as to provide, via the motor chamber outer wall, heat exchange between the hydrogen gas in the motor chamber and the liquid hydrogen in the motor chamber guiding flow line.
3 . The pump unit according to claim 1 , further comprising a fan disposed in the motor chamber, wherein
the housing includes a gas discharge port configured to allow the hydrogen gas introduced into the motor chamber to be discharged to the external gas line, and
the fan is configured to cause the hydrogen gas introduced into the motor chamber through the gas introduction port to flow toward the gas discharge port.
4 . The pump unit according to claim 3 , wherein
the mechanical seal is arranged relative to the pump chamber and the rotation shaft such that leaks of liquid hydrogen from the pump chamber enter into the motor chamber, and
the fan is further configured to cause flow toward the gas discharge port of the hydrogen gas introduced into the motor chamber through the gas introduction port and of hydrogen gas formed by vaporization in the motor chamber of liquid hydrogen that has leaked by the mechanical seal into the motor chamber.
5 . The pump unit according to claim 1 , further comprising at least two rotary bearings, mounted to the motor chamber housing and aligned to a common rotation axis, wherein
the rotation shaft, rotatably supported by the at least two rotary bearings and extending in the motor chamber and into the pump chamber in an axial direction along the common rotation axis; and
the motor chamber housing configured to allow a lubricating flow to the at least two rotary bearings of the hydrogen gas introduced into the motor chamber.