Variable Displacement Pump Speed Control for RO Yield
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Solution Overview
Problem
Existing reverse osmosis systems with positive displacement arrangements face challenges in achieving flexible and energy-efficient operation, leading to increased specific energy consumption and limited control over production rates, primarily due to reliance on bypass or drain valves for yield variation.
Innovation Solution
The method involves dividing the feed stream into two portions, one fed to a membrane arrangement via a positive displacement pump and the other via a variable-speed delivery unit, allowing independent speed control of both units to optimize operating conditions with minimal energy and volume losses, enabling different operational modes such as energy-saving or membrane-preserving operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If yield variation is achieved by means of bypass or drain valves in positive displacement systems, then production rates can be controlled, but specific energy consumption increases
Solution Approach 1:
The invention applies dynamics by making the positive displacement pump's displacement volume variable rather than fixed. The pump mechanism includes adjustable parameters that allow the displacement volume per revolution to be changed, enabling yield control without energy-wasting bypass valves. This dynamic adjustment directly addresses the contradiction by providing productivity control through a mechanism that does not inherently waste energy.
Solution Approach 2:
The invention changes the parameter of displacement volume from fixed to variable. By allowing the positive displacement pump to operate with adjustable displacement volumes, the system can optimize energy efficiency while controlling production rates. This parameter change eliminates the need for bypass valves that cause energy losses, directly resolving the technical contradiction between productivity control and energy consumption.
2Stress or pressure
If a single positive displacement pump is used for feed delivery, then high pressures can be achieved at small volume flows, but flexible operation with minimal energy losses is limited
Solution Approach 1:
The invention makes the positive displacement pump dynamic by enabling variable displacement volume adjustment. This allows the pump to adapt to different operational requirements while maintaining high pressure capability, thereby achieving both pressure performance and operational flexibility without requiring multiple pumps or complex valve systems.
Solution Approach 2:
The variable displacement positive displacement pump serves multiple functions: it can operate at high pressures for small flows and also adjust to different flow rates and pressure conditions. This multi-functionality replaces what would traditionally require multiple fixed-displacement pumps or complex valve arrangements, achieving versatility while maintaining pressure capability.
3Productivity
If bypass or drain valves are used for yield control, then production rates can be varied, but volume losses occur
Solution Approach 1:
The variable displacement positive displacement pump allows yield control by adjusting the pump's displacement volume rather than using bypass or drain valves. This dynamic adjustment mechanism controls production rates by changing the pump's output volume per revolution, eliminating the volume losses that would occur with traditional valve-based yield control methods.
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 approach allows for flexible operation with reduced energy and volume losses, enabling efficient use of membranes and energy sources like solar or wind power, while maintaining control over production rates without the need for bypass or drain valves, thus optimizing system performance.
Implementation Method 1
a positive displacement arrangement is used for energy recovery. In such positive displacement systems, the liquid is delivered by self-contained volumes. In this case, pressure is transferred from the retentate stream to the feed stream.
Implementation Method 2
The liquid is subjected to a pressure which is above the osmotic pressure, and water molecules diffuse through the membrane, while the dissolved salts are retained.
Implementation Method 3
The liquid is subjected to a pressure which is above the osmotic pressure, and water molecules diffuse through the membrane
Data Source
AI summary
The invention relates to a method for treating a liquid. A feed stream is separated into a permeate stream and a retentate stream by means of a member arrangement. At least a portion of the retentate stream is discharged from the member arrangement via a displacer arrangement as a defined displacer volume. The feed stream is divided into a portion that is fed into the membrane arrangement via a displacer arrangement as a defined displacer volume and into a portion that is fed to the membrane arrangement by means of a conveying unit. The yield is varied by changing the ratio of the speed of the conveying unit to the speed of the displacer arrangement.