Integrated RO-PRO System with Mechanical Energy Coupling
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Solution Overview
Problem
Existing systems for combined reverse osmosis (RO) and pressure retarded osmosis (PRO) lack efficient practical implementations, particularly in terms of energy recovery and operational versatility, with prior art focusing more on thermodynamic models rather than practical construction and operation of energy recovery devices.
Innovation Solution
A system comprising a mechanically connected RO and PRO subsystem with a hydraulic pump and motor configuration that allows direct energy transfer without conversion losses, utilizing a combination of axial piston pumps and motors, and an induction motor for efficient energy management and distribution, along with energy storage and recovery devices to optimize operation modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If energy recovery devices are used to transfer hydraulic energy from pressurized brine to feed solution, then energy efficiency of reverse osmosis is improved, but device complexity and construction difficulty increase
Solution Approach 1:
The patent combines the RO subsystem and PRO subsystem into a single integrated system where the PRO subsystem generates hydraulic energy that directly powers the RO subsystem through mechanical coupling, eliminating the need for separate energy recovery devices and reducing overall system complexity
Solution Approach 2:
The pressurized brine from the RO subsystem serves dual purposes: it is both a waste stream to be disposed of and a valuable energy source that drives the PRO membrane process, which in turn generates power for the RO feed pump, creating a multi-functional energy cycle
2Loss of energy
If RO and PRO subsystems are mechanically connected for direct energy transfer, then energy losses are reduced, but system complexity and operational difficulty increase
Solution Approach 1:
The PRO subsystem automatically generates hydraulic energy from the concentration gradient between feed and draw solutions, and this energy self-regulates the RO feed pump operation through direct mechanical coupling, reducing the need for external control systems and simplifying operation
Solution Approach 2:
The system incorporates inherent feedback where the performance of the PRO subsystem (energy generation) directly influences the operation of the RO subsystem (feed pressurization), creating a self-balancing energy cycle that automatically adjusts to operational conditions
3Productivity
If concentrated brine is removed from RO chamber to avoid excessive osmotic pressure, then RO process continuity is maintained, but energy recovery opportunities are lost
Solution Approach 1:
The patent converts the previously harmful concentrated brine stream, which needed to be discarded to maintain process continuity, into a beneficial energy source by feeding it to the PRO subsystem where its high osmotic pressure drives water extraction and generates hydraulic energy
4Use of energy by moving object
If hydraulic pump and motor are directly mechanically connected, then energy transfer efficiency is improved, but system reliability and fault tolerance decrease
Solution Approach 1:
The system divides the hydraulic energy transfer into separate functional components (hydraulic pump, hydraulic motor, mechanical coupling) that can operate independently to some extent, allowing for localized maintenance and reducing the impact of failures on the entire system
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enhances the energy efficiency and operational flexibility of the combined RO-PRO system, enabling faultless direct mechanical connections, reduced energy losses, and surplus electrical energy generation, while allowing for versatile operation conditions and mineral harvesting.
Implementation Method 1
Osmosis is a process wherein solvent moves across a semipermeable membrane from the membrane's side facing a lower solute concentration towards the membrane's side facing a higher solute concentration
Implementation Method 2
In reverse osmosis, a pressure exceeding the osmotic pressure is applied to the side of the higher solute concentration thus reverting the energy balance of the osmotic system
Implementation Method 3
Pressure retarded osmosis, PRO, is based on forward osmosis with a net flow towards the higher solute concentration but external pressure is again applied against the osmotic pressure gradient. In a PRO process, energy can be produced based on concentration, e.g., salinity, gradients between a feed and a draw solution
Data Source
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AI summary
The present invention relates to a system for reverse osmosis, RO, and for pressure retarded osmosis, PRO, comprising: a RO subsystem (10) with a high-pressure RO chamber (11) and a low-pressure RO chamber (12) separated by a RO membrane (13), the high-pressure RO chamber (11) having a RO feed inlet (14) and a brine outlet (15) and the low-pressure RO chamber (12) having a permeate outlet (16); a PRO subsystem (20) with a high-pressure PRO chamber (21) and a low-pressure PRO chamber (22) separated by a PRO membrane (23), the high-pressure PRO chamber (21) having a draw inlet (24) and a draw outlet (25) and the low-pressure PRO chamber (22) having PRO feed inlet (26) and a PRO feed outlet (27); an induction motor (30) having a stator and a rotor, wherein the rotor is mechanically connected to an input shaft of a hydraulic pump (31) configured for providing a feed solution to the RO feed inlet (14) and to an output shaft of a hydraulic motor (32) configured for receiving a draw solution from the draw outlet (25). The invention further relates to a method for operating such system for RO/PRO and to the use of such system.