A power recovery device which is used in a liquid processing apparatus in which raw water as externally supplied water containing a plurality of components is supplied to a reverse osmosis membrane through a pressure raising unit and extracts a part of fresh water from the pressure raised raw water by the reverse osmosis membrane, and which supplies raw water a pressure of which is raised by using a pressure of remaining raw water from which the part of the fresh water is extracted by the reverse osmosis membrane to the reverse osmosis membrane, in addition to the pressure raised raw water from the pressure raising unit,
- the power recovery device comprising:
- a housing having an internal space;
- a center shaft fixed in the internal space of the housing and having an outer circumferential surface and at least one end portion protruding outside the housing;
- and a rotary member accommodated in the internal space of the housing such that the rotary member is rotatable on the outer circumferential surface of the center shaft, having an inner circumferential surface opposing the outer circumferential surface of the center shaft and an outer circumferential surface positioned outside the center shaft in a radial direction of the center shaft, and including a plurality of channels arranged at equal intervals in a circumferential direction of the center shaft and each extending between the inner circumferential surface thereof and the outer circumferential surface thereof,
- wherein at least one set of two pairs of chambers opposing the outer circumferential surface of the rotary member and divided from each other is provided in the internal space of the housing,
- at least one set of two pairs of openings opening in the outer circumferential surface of the center shaft to be equal in number to the chambers to oppose the at least one set of the chambers in the internal space of the housing through the rotary member, and at least one set of two pairs of passages extending through the center shaft from the at least one set of the openings and opening in the at least one end portion of the center shaft, are formed in the center shaft,
- one pair of the chambers symmetrically arranged with respect to the center shaft in the one set of the chambers in the internal space of the housing is configured to be introduced with the externally supplied raw water and to cause the externally supplied raw water to push the plurality of channels in the outer circumferential surface of the rotary member exposed in the one pair of chambers, in a predetermined circumferential direction of the outer circumferential surface so as to rotate the rotary member,
- the other pair of the chambers symmetrically arranged with respect to the center shaft in the one set of the chambers is connected to a channel of the pressure raised raw water between the pressure raising unit and the reverse osmosis membrane,
- one pair of the openings of the one set of openings in the outer circumferential surface of the center shaft, opposing the one pair of the chambers through the rotary member are communicated with an outside through one pair of the passages corresponding to the one pair of the openings in the center shaft, and
- the other pair of the openings of the one set of the openings in the outer circumferential surface of the center shaft, opposing the other pair of the chambers through the rotary member is introduced with the remaining raw water through the other pair of the passages corresponding to the other pair of the openings in the center shaft.