Reverse Osmosis HEMI Control for Membrane Shock Reduction
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Solution Overview
Problem
Reverse osmosis systems face challenges in minimizing mechanical stress on membranes due to rapid pressure changes during startup, which can lead to excessive mechanical shock and potential damage.
Innovation Solution
A hydraulic energy management integration system (HEMI) is implemented, comprising a pump portion, turbine portion, and motor, with a programmable logic controller to control the pressure rise gradually, using a variable frequency drive to manage the speed of the turbine and pump, and a variable nozzle to regulate brine flow, ensuring a controlled pressure increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a pump rapidly ramps up to full pressure during startup, then the system reaches operating pressure quickly, but excessive mechanical shock occurs at the membrane array
Solution Approach 1:
The system performs preliminary action by starting the pump at low speed and gradually increasing it to full speed. The controller manages the variable frequency drive to ramp up the pump motor speed progressively, allowing the membrane array to acclimate to pressure increases without experiencing sudden mechanical shock.
Solution Approach 2:
The system applies dynamics by making the pump motor speed variable rather than fixed. The variable frequency drive allows continuous adjustment of motor speed during startup, enabling the system to optimize between rapid pressure buildup and mechanical shock prevention by dynamically changing operational parameters.
2Object-affected harmful factors
If a feed throttle valve is used to gradually open during startup, then mechanical shock is minimized, but the system requires additional valve components and control complexity
Solution Approach 1:
The system replaces the mechanical valve control approach with an electrical/control-based solution. Instead of using a feed throttle valve with mechanical actuation, the invention uses a variable frequency drive to control pump motor speed, substituting mechanical pressure regulation with electrical speed control. This eliminates the need for additional throttle valves and their associated control mechanisms.
Solution Approach 2:
The system changes the controlled parameter from valve opening position to motor speed. By controlling the pump motor speed through variable frequency drive rather than regulating flow through a throttle valve, the system achieves gradual pressure buildup while simplifying the overall device architecture and reducing component count.
3Productivity
If the pump starts at high speed to quickly achieve operating pressure, then productivity is improved, but power surges occur during startup
Solution Approach 1:
The system performs preliminary action by initiating pump operation at low speed before gradually increasing to full operating speed. This staged approach allows the motor to draw less initial power, avoiding power surges, while still achieving full productivity eventually through controlled acceleration managed by the variable frequency drive.
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 effectively reduces mechanical stress on membranes by gradually increasing pressure, minimizing shock and extending the lifespan of the membranes, while also reducing power surges during startup and maintaining flow during shutdown for cooling.
Implementation Method 1
The motor 22 may be driven by a variable frequency drive (VFD) 24
Implementation Method 2
A reverse osmosis system involves pressurizing a solution with an applied pressure greater than an osmotic pressure created by the dissolved salt within the solution
Implementation Method 3
The osmotic pressure is generally proportional to the concentration level of the salt
Implementation Method 4
During start-up the turbine has a retarding, i.e. power adsorbing function
Implementation Method 5
A hydraulic energy management integration system (HEMI) is implemented
Data Source
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AI summary
A reverse osmosis system and method of operating the same includes a first pump (28) receiving feed fluid at a first pressure and increasingly pressurizing the feed fluid to a second pressure higher than the first pressure and comprising hydraulic energy management integration system (HEMI) having a turbine portion (114), a pump portion (112) and a motor (116). The brine outlet fluid is in fluid communication with the turbine portion. The reverse osmosis system also includes a second pump (20) and a controller controlling the motor to retard rotation of the HEMI while the first pump increasingly pressurizes the feed fluid to the second pressure. The controller (140) also increases a HEMI speed so that feed fluid pressure increases above the second pressure, and, when a feed fluid reaches the second pressure at the fluid inlet, controls the second pump to increase the feed fluid pressure to a third pressure. The controller to reduces the HEMI speed after the third pressure and changes the HEMI speed based on a membrane pressure.