US-12624709-B2 - Rotary pressure exchanger

US12624709B2US 12624709 B2US12624709 B2US 12624709B2US-12624709-B2

Abstract

A rotary pressure exchanger includes a housing and a rotor. Channels are inside the rotor to transfer pressure from a first fluid to a second fluid. Each channel extends parallel to the axis of rotation, and the housing includes a first inlet port for supplying the first fluid to the channels, a first outlet port for discharging the first fluid from the channels, a second inlet port for suppling the second fluid to the channels, and a second outlet port for discharging the second fluid from the channels. The first and second inlet ports are radial inlet ports, such that the first fluid and the second fluid enter the rotor in a radial direction perpendicular to the axial direction, and the first outlet port and the second outlet port are radial outlet ports, such that the first fluid and the second fluid leave the rotor in the radial direction.

Inventors

Bartosz KUS
Karel DE RAEVE

Assignees

SULZER MANAGEMENT AG

Dates

Publication Date: 20260512
Application Date: 20230516
Priority Date: 20220520

Claims (18)

1 . A rotary pressure exchanger for transferring pressure from a first fluid to a second fluid, comprising: a housing; and a rotor mounted within the housing, and configured to rotate about an axis of rotation defining an axial direction; a plurality of channels disposed inside the rotor, and configured to transfer pressure from the first fluid to the second fluid, each channel of the plurality of channels extends parallel to the axis of rotation, the housing comprising a first inlet port configured to supply the first fluid to the plurality of channels in the rotor, a first outlet port configured to discharge the first fluid from the plurality of channels in the rotor, a second inlet port configured to supply the second fluid to the channels in the rotor, and a second outlet port configured to discharge the second fluid from the plurality of channels in the rotor, each channel of the plurality of channels extends from a first axial end to a second axial end so as to form an opening in at least one surface of the first or second axial end, at least one of the first axial end and the second axial end of each channel of the plurality of channels includes a closing element, the closing element for each channel of the plurality of channels attached to the at least one of the first axial end and the second axial end to close the opening in the at least one surface of the first or second axial end, and the first inlet port and the second inlet port being radial inlet ports, such that the first fluid and the second fluid are capable of entering the rotor in a radial direction perpendicular to the axial direction, and the first outlet port and the second outlet port being radial outlet ports, such that the first fluid and the second fluid are capable of leaving the rotor in the radial direction.
2 . The rotary pressure exchanger in accordance with claim 1 , wherein the rotor extends from a first rotor end in the axial direction to a second rotor end, the rotor comprises a circumferential surface delimiting the rotor with respect to the radial direction, each channel comprises a first opening and a second opening for the fluids, and each first opening and each second opening are arranged in the circumferential surface of the rotor.
3 . The rotary pressure exchanger in accordance with claim 1 , further comprising a plurality of bearing flow passages configured to hydrostatically support of the rotor.
4 . The rotary pressure exchanger in accordance with claim 2 , further comprising a first end cover and a second end cover, with each of the first end cover and the second end cover being arranged stationary with respect to the housing, and the rotor is arranged between the first end cover and the second end cover regarding the axial direction.
5 . The rotary pressure exchanger in accordance with claim 4 , wherein each of the first end cover and the second end cover is a ceramic material.
6 . The rotary pressure exchanger in accordance with claim 4 , wherein each of the first rotor end and the second rotor end comprises a bearing pin extending in the axial direction and configured coaxially with the axis of rotation, each of the first end cover and the second end cover comprises a bearing recess configured to receive one of the bearing pins, and each bearing pin engages with one of the bearing recesses.
7 . The rotary pressure exchanger in accordance with claim 6 , wherein at each of the first rotor end and the second rotor end, a radial bearing flow passage and an axial bearing flow passage are disposed between the bearing recess and the bearing pin engaging the bearing recess, each radial bearing flow passage is configured to provide hydrostatic radial support of the rotor, and each axial bearing flow passage is configured to provide hydrostatic axial support of the rotor.
8 . The rotary pressure exchanger in accordance with claim 6 , wherein the rotor comprises an axle and a rotor body, the axle comprises both bearing pins and extends from the bearing pin at the first rotor end to the bearing pin at the second rotor end, the rotor body comprises all of the plurality of channels, and the rotor body is fixedly connected to the axle in a torque proof manner.
9 . The rotary pressure exchanger in accordance with claim 8 , wherein the axle is a first material, the rotor body is a second material, and the first material is different from the second material.
10 . The rotary pressure exchanger in accordance with claim 8 , wherein the axle is a hollow axle comprising a central opening extending completely through the axle in the axial direction, each of the first end cover and the second end cover comprises a central bore aligned with the central opening, with each central bore the first end cover and the second end cover extending completely through a respective end cover in the axial direction, a bolt extends in the axial direction through each central bore the first end cover and the second end cover and through the central opening, and the bolt is secured to each of the first end cover and the second end cover.
11 . The rotary pressure exchanger in accordance with claim 10 , wherein the bolt comprises a central core extending in the axial direction along an entire length of the bolt, and a sleeve arranged coaxially with the core and abutting against the core, the sleeve is a first material, the central core is a second material, and the first material is different from the second material.
12 . The rotary pressure exchanger in accordance with claim 4 , further comprising a rotor sleeve extending regarding the axial direction from the first end cover to the second end cover, with the rotor sleeve arranged stationary with respect to the housing, the rotor is arranged within the rotor sleeve, so that the rotor sleeve surrounds the circumferential surface of the rotor.
13 . The rotary pressure exchanger in accordance with claim 1 , wherein each first axial end includes a first plug to close the first axial end, and each second axial end includes a second plug to close closing the second axial end.
14 . The rotary pressure exchanger in accordance with claim 1 , wherein in each channel of the plurality of channels a freely sliding separator is provided to reduce a mixing of the first fluid and the second fluid.
15 . The rotary pressure exchanger in accordance with claim 9 , wherein the first material is a ceramic material and the second material is a metallic material.
16 . The rotary pressure exchanger in accordance with claim 11 , wherein the first material is a ceramic material and the second material is a metallic material.
17 . The rotary pressure exchanger in accordance with claim 1 , wherein for each channel of the plurality of channels, the closing element is configured to seal the channel.
18 . The rotary pressure exchanger in accordance with claim 1 , wherein for each channel of the plurality of channels, a sealing element is disposed between the closing element and the at least one of the first axial end and the second axial end of each channel of the plurality of channels.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application claims priority to European Patent Application 22174648.0, filed May 20, 2022, the contents of which are hereby incorporated by reference in its entirety. BACKGROUND Technical Filed The disclosure relates to a rotary pressure exchanger for transferring pressure from a first fluid to a second fluid in accordance with the preamble of the independent claim. Rotary pressure exchangers are used to transfer energy in the form of pressure from a first fluid available at a high pressure to a second fluid available at a low pressure. Usually, the energy transfer takes place by a positive displacement of the fluids following Pascal's principle. Such rotary pressure exchangers are configured with a rotor which is driven by the fluids or by an external motor. A well-known application of rotary pressure exchangers is the field of reverse osmosis systems, for example Sea Water Reverse Osmosis (SWRO) for desalination of seawater or brackish water. Here, the rotary pressure exchanger is used as an efficient energy recovery device. BACKGROUND INFORMATION In some reverse osmosis systems a semipermeable membrane can be passed by the water or a solvent but not by solutes like dissolved solids, molecules or ions. For reverse osmosis the membrane is supplied with a pressurized feed fluid for example seawater. Only the solvent, for example the water, can pass the membrane and will leave the membrane unit as permeate fluid, for example fresh water. The remaining part of the feed fluid that does not pass through the membrane is discharged from the membrane unit as concentrate fluid, for example brine. The feed fluid has to be supplied to the membrane with a high pressure to overcome the osmotic pressure. Thus, reverse osmosis typically is a process where a pressurized feed fluid is required and the concentrate fluid leaving the membrane unit still has a considerably large residual pressure that enables to recover a part of the pressurizing energy as mechanical energy. In seawater desalination, for example, the required pressure of the feed fluid (seawater) may be from 45 bar to 75 bar depending among others on the salinity and the temperature of the seawater. The pressure in the fresh water (permeate fluid) can be between zero and three bars, the pressure in the brine (concentrate fluid) is typically between 2 and 5 bars less than the feed pressure, i.e. 40-73 bar. Rotary pressure exchangers are used to transfer pressure from the brine, Which is still at a considerably high pressure, to the feed fluid, thus recovering energy from the brine. The rotor of a rotary pressure exchanger is typically designed to include straight axially oriented ducts or channels, in which the pressure transfer takes place by positive displacement of the fluids. It is known to arrange the rotor between two stationary end covers which are used to supply the fluids to the rotor and to discharge the fluids from the rotor. For positioning and supporting the rotor it is known to use an axle which is arranged at the center of the rotor as it is disclosed for example in U.S. Pat. No. 10,125,796. Another conventional solution is a sleeve positioning concept, where the rotor is surrounded by a stationary sleeve. During operation of the device the narrow gap between the rotor and the sleeve provides a hydrodynamic support of the rotor. SUMMARY In conventional rotary pressure exchangers, the fluids are supplied and discharged through the end covers and in axial direction into and from the rotor. Each end cover includes high and low pressure ports for the fluids. In each end cover the high and the low pressure port are separated by a sealing space formed between the stationary face between the ports and the end faces of the rotor. In order to limit the leakage between the ports extremely small clearances between the end covers and the rotor are required. It has been determined that in this makes the manufacturing process complex and expensive and might require special materials. Due to the short distance between the high pressure port and the low pressure port the resulting leakage limits the efficiency of the device, despite using extremely narrow clearances (typically in the range of several micrometers). Based on these deficiencies in the conventional systems, it is therefore an object of the disclosure to propose a rotary pressure exchanger with an improved efficiency. The subject matter of embodiments of the invention satisfying this object is characterized by the features disclosed herein. Thus, according to the disclosure, a rotary pressure exchanger is proposed for transferring pressure from a first fluid to a second fluid, comprising a housing and a rotor mounted within the housing for rotation about an axis of rotation defining an axial direction, wherein a plurality of channels is disposed inside the rotor for transferring pressure from the first fluid to the second fluid, wherein each channel extends