Multi-Cylinder Pump with Phase-Shifted Valving for Desalination

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Solution Overview

Problem

Desalination systems using reverse osmosis membranes face inefficiencies due to high-pressure saline solutions requiring effective pumping mechanisms that are either manually operated or mechanically driven, lacking optimal energy recovery and efficiency in larger systems.

Innovation Solution

A pump design featuring four cylinders with double-acting pistons, a common drive system, and phase-shifted valving to manage intake and discharge strokes efficiently, allowing for energy recovery from high-pressure concentrate and reducing pressure losses through a spool valve mechanism, potentially constructed from plastic materials for corrosion resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single cylinder pump with manual lever operation is used, then the device complexity is reduced, but the productivity and energy efficiency deteriorate

Engineering Contradiction:

Improvepump structure complexityVSAvoiddesalination output

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The pump is divided into multiple cylinders (typically three or more) operating in sequence, with each cylinder having its own piston and valve assembly. This segmentation allows continuous operation where one cylinder is always in the discharge phase, thereby increasing productivity while maintaining manageable complexity through modular design

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The pump utilizes periodic reciprocating motion of pistons in a cyclic sequence, where each piston alternates between intake and discharge strokes. This periodic action ensures continuous flow to the membrane unit and maximizes the utilization of high-pressure concentrate energy recovery

Inventive Principle:

Principle #19Periodic action

2Productivity

If mechanically driven multi-cylinder pumps are used, then the productivity increases, but the device complexity and energy consumption increase

Engineering Contradiction:

Improvedesalination outputVSAvoidpump energy consumption

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The system incorporates an energy recovery mechanism where high-pressure concentrate from the membrane unit is fed back to drive the pump pistons during the intake stroke. This feedback loop captures wasted energy from the concentrate stream and converts it into useful mechanical work, significantly reducing the net energy consumption of the pump

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The pump design allows the high-pressure concentrate to perform part of the pumping work itself by driving the pistons during the recovery stroke. The system essentially uses its own waste energy output to assist in its own operation, reducing external energy requirements

Inventive Principle:

Principle #25Self-service

3Device complexity

If traditional valving mechanisms are used, then the device complexity is lower, but the loss of energy increases due to lost motion

Engineering Contradiction:

Improvevalving mechanism complexityVSAvoidpressure loss

Core Design Contradiction:

Device complexityVSLoss of energy

Solution Approach 1:

The patent replaces traditional mechanical lost-motion valving mechanisms with a direct-acting valve system where the piston rod itself controls the valve timing. This substitution eliminates mechanical play and dead centers, reducing energy loss and improving the efficiency of pressure transmission to the membrane unit

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical 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

The pump design enhances energy recovery and efficiency in desalination systems by managing pressure effectively, reducing energy consumption, and offering a reliable operation with minimal lost motion mechanisms, suitable for large-scale desalination applications.

Implementation Method 1

a saline solution is supplied to a membrane unit at high pressure, for example between 650 and 950 Psi (4500 to 6500 kPa)

Methodology Applied

Scientific EffectPressure gradient: Pressure Gradient

Implementation Method 2

the valving being such as to connect the recovery chamber alternately to an inlet manifold for an intake stroke of the piston relative to the recovery chamber, and to an outlet manifold for a discharge stroke

Methodology Applied

Scientific EffectPhase change: Phase Change

Data Source

PatentUS11378067B2Pump and a desalination system including the pump

Publication Date: 2022.07.05 KATADYN DESALINATION LLC

AI summary

A pump adapted for use in desalination systems that has four cylinders, with a double acting piston in each cylinder. Each cylinder and piston thereby defines a feed chamber and a recovery chamber. The pistons are connected to a common drive. The connection to the common drive is such that the pistons reciprocate in a sequence equally spaced in time. Reciprocating valving for each piston is driven by the common drive to be 90 degrees out of phase with the respective piston.The valving connects the recovery chamber alternately to an inlet manifold for an intake stroke of the piston relative to the recovery chamber, and to an outlet manifold for a discharge stroke of the piston relative to the recovery chamber. There is a brief period of closure coinciding with top dead centre and bottom dead centre of the piston, during which the recovery chamber is blocked off from both the inlet and outlet manifolds. The reciprocating valving is midway between its top dead centre and bottom dead centre during the period of closure.