Subsea RO Desalination Modules Using Hydrostatic Pressure
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Solution Overview
Problem
Existing desalination plants require substantial land area and are often unavailable or expensive near areas needing desalinated water, and existing subsea desalination systems face challenges in efficiently utilizing hydrostatic pressure for desalination without additional pumps.
Innovation Solution
A modular subsea desalination system utilizing hydrostatic pressure greater than osmotic pressure to drive water through RO-membranes, with a circulation pump downstream of the membranes, and a transport pump for desalinated water, allowing for efficient seawater desalination and modular, retrievable modules for maintenance and expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional desalination plant is built on land, then it can provide desalinated water, but it requires substantial land area which is unavailable or expensive near areas needing desalinated water
Solution Approach 1:
The invention relocates the desalination plant from land-based (2D surface) to subsea (3D underwater space), utilizing the vertical dimension and offshore space to eliminate land area constraints while maintaining desalinated water production capability
Solution Approach 2:
The invention utilizes hydrostatic pressure from seawater depth (hydraulic principle) to drive the reverse osmosis process, eliminating the need for large land-based pump stations and infrastructure while enabling desalination directly at the seabed
2Productivity
If additional pumps are used to drive flow through RO membranes, then desalination can occur at shallower depths, but it increases energy consumption and system complexity
Solution Approach 1:
The system utilizes the natural hydrostatic pressure from the seawater depth itself to drive the reverse osmosis process, making the environment provide the driving force rather than requiring external energy input from pumps, thus reducing energy consumption
Solution Approach 2:
The invention changes the operating pressure parameter by utilizing the natural hydrostatic pressure gradient available at subsea depths (greater than osmotic pressure), eliminating the need for additional pumping energy that would be required at shallower depths
3Productivity
If additional pumps are used to drive flow through RO membranes, then desalination can occur at shallower depths, but it increases system complexity
Solution Approach 1:
The system uses the natural hydrostatic pressure from seawater depth to drive flow through the RO membranes, eliminating the need for additional pumping equipment and reducing system complexity while maintaining desalinated water production
Solution Approach 2:
The invention extracts and eliminates the unnecessary pump components from the system by utilizing the natural hydrostatic pressure environment, simplifying the overall system architecture while preserving the core desalination function
4Ease of repair
If desalination modules are made retrievable and modular, then maintenance and expansion become easier, but it increases device complexity
Solution Approach 1:
The desalination plant is divided into separate modular components (RO membrane modules, pump modules, control modules) that can be independently installed, retrieved, and maintained, facilitating ease of repair while the standardization of these modules minimizes the increase in overall system complexity
5Productivity
If circulation pump is located upstream of RO membranes, then it can drive flow through membranes, but it increases the pressure requirement and energy consumption
Solution Approach 1:
Instead of placing the circulation pump upstream to push water through the membranes (requiring high pressure), the pump is placed downstream to pull water through the membranes using the natural hydrostatic pressure gradient, thereby reducing energy consumption while maintaining productivity
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 system efficiently desalinated water using hydrostatic pressure, reducing land requirements and enabling flexible, scalable, and reliable operation with minimal downtime for maintenance.
Implementation Method 1
Reverse osmosis (RO) membranes can be placed in seawater at a water depth providing to a hydrostatic pressure greater than the osmotic pressure (π). A hydrostatic pressure greater than π can be utilized in a desalination process to push water molecules through RO-membranes
Implementation Method 2
A hydrostatic pressure greater than π can be utilized in a desalination process to push water molecules through RO-membranes without requiring additional pressure
Implementation Method 3
The transport pump generates a pressure difference. This decreases the inlet pressure of the pump, thus the permeate pressure of the RO membranes is equal to the inlet pressure of the transport pump
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The present invention relates to a modularized subsea desalination system. A subsea desalination template includes subsea desalination module zones 41 and module fluid couplings 46. A desalinated water outlet is in fluid connection with the module fluid coupling 46 in the subsea desalination module zone. Subsea desalination modules 5 with reverse osmosis cartridges 23 are in fluid connection with a subsea template fluid coupling 47, a seawater inlet section and a concentrated seawater outlet section. A transport pump assembly 48 for desalinated water in a pump module 17 is in fluid connection with the subsea desalination template 1 and the desalination modules 5. A seawater circulation pump 49 is in fluid connection with a seawater side of the at least one reverse osmosis cartridge 23. A desalinated water pipeline 2 convey fluid from the desalinated water transport pump assembly 48 to a location above a sea level. Furthermore, the invention relates to a subsea desalination module 5 and a method exchanging a subsea desalination module 5 requiring service.