Two-Stage Reverse Osmosis Desalination with Pressure Exchange
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Solution Overview
Problem
Current desalination technologies, particularly reverse osmosis systems, face challenges in achieving high recovery rates and energy efficiency when treating high-saline water, leading to limited fresh water production and increased energy consumption.
Innovation Solution
A desalination apparatus with a two-stage reverse osmosis process, where the ratio of pressure vessels in the first and second stages is optimized between 6:19 to 9:16, and optionally incorporating a third stage with brackish water reverse osmosis or a Pelton turbine for energy recovery, to enhance water quality and quantity while reducing process load and energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high pressure is applied to increase recovery rate, then fresh water production increases, but energy consumption increases and membrane contamination worsens
Solution Approach 1:
The patent divides the single-stage high-pressure reverse osmosis process into two stages: a first stage operating at high pressure for initial desalination, and a second stage operating at lower pressure for further treatment. This segmentation allows the system to achieve high recovery rates without subjecting the entire process to high pressure, thereby reducing overall energy consumption and membrane contamination while maintaining fresh water production.
2Productivity
If high pressure is applied to increase recovery rate, then fresh water production increases, but membrane contamination increases
Solution Approach 1:
The patent divides the single-stage high-pressure reverse osmosis process into two stages: a first stage operating at high pressure for initial desalination, and a second stage operating at lower pressure for further treatment. This segmentation allows the system to achieve high recovery rates without subjecting the entire process to high pressure, thereby reducing overall energy consumption and membrane contamination while maintaining fresh water production.
3Use of energy by moving object
If two-stage reverse osmosis is implemented, then energy efficiency improves, but device complexity increases
Solution Approach 1:
The patent combines the concentrate streams from both the first and second stages into a single concentrate outlet, and integrates pressure exchanger units that utilize the pressure from concentrate water to pre-pressurize feed water. This merging approach reduces the number of independent high-pressure systems needed, simplifying the overall device complexity while maintaining the energy efficiency benefits of the two-stage configuration.
4Productivity
If conventional single-stage reverse osmosis is used, then device complexity is low, but fresh water production is limited
Solution Approach 1:
The patent divides the single-stage high-pressure reverse osmosis process into two stages: a first stage operating at high pressure for initial desalination, and a second stage operating at lower pressure for further treatment. This segmentation allows the system to achieve high recovery rates without subjecting the entire process to high pressure, thereby reducing overall energy consumption and membrane contamination while maintaining fresh water production.
Solution Approach 2:
The patent introduces pressure exchanger units as intermediary devices that transfer pressure energy from the concentrate stream to the feed water. This intermediary mechanism enables the second stage to operate efficiently at lower pressure by pre-pressurizing the feed water, thereby increasing fresh water production without requiring proportionally higher pressure input.
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
The proposed solution increases the quantity and quality of fresh water production, reduces membrane contamination, and decreases energy consumption, making the process more efficient and cost-effective for high-saline water treatment.
Implementation Method 1
water treatment method using reverse osmosis is a way to extract fresh water by arranging a semipermeable membrane therebetween and applying reverse osmosis pressure which is higher than osmosis pressure to sea water
Implementation Method 2
applying reverse osmosis pressure which is higher than osmosis pressure to sea water
Implementation Method 3
Pressure exchanger increase pressure of diverged raw water by using hydraulic pressure of the concentrate water
Implementation Method 4
a Pelton turbine for generating electric power by means of the second concentrate water
Data Source
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AI summary
The present invention relates to a desalination apparatus for high-saline water comprising: a first stage module into which raw water is introduced as a first inflow water and which treats the first inflow water by a reverse osmosis process to discharge a first product water and a first concentrate water; a second stage module into which a second inflow water that is a mixture of the raw water and the first concentrate water is introduced and which treats the second inflow water by a reverse osmosis process to discharge a second product water and a second concentrate water; and a pressure exchanger which increases pressure of the raw water that will be mixed with the first concentrate water by pressure of the second concentrate water; wherein a ratio of the number of pressure vessels constituting the first stage module to the number of pressure vessels constituting the second stage module is in the range of 6:9 to 9:16.