Multiple-Effect Vacuum Distillation for Low-Energy Water Purification
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Solution Overview
Problem
Current water desalination technologies, such as MSF and RO systems, are energy-intensive, costly, and have high operational and capital expenses, with MSF systems requiring complex processes and large land areas, and RO systems needing high-pressure pumps and complex pre- and post-treatment, while also generating a large volume of poorly quality concentrate that is difficult to dispose of.
Innovation Solution
A method and apparatus using multiple-effect vacuum distillation with electrical heating to evaporate and condense water at lower temperatures, capable of generating its own power and integrating with existing systems, reducing capital and maintenance costs, and minimizing ecological impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If MSF systems are used for desalination, then water purity is improved (99% TDS removal), but capital cost and device complexity increase due to exotic materials and complex flash chambers
Solution Approach 1:
The system divides the distillation process into multiple effect stages, where each effect chamber operates at progressively lower pressures and temperatures. This segmentation allows the use of conventional materials instead of exotic materials while maintaining high purification efficiency through cascaded phase change processes.
Solution Approach 2:
The system changes the operating parameters (pressure and temperature) across different effect stages, with each subsequent effect operating at lower parameters than the previous one. This parameter gradient enables efficient heat recovery and allows the use of standard construction materials throughout the system.
2Manufacturing precision
If MSF systems are used for desalination, then water purity is improved, but land area requirement increases due to large equipment and tankage size
Solution Approach 1:
The system employs a nested configuration where condenser surfaces are positioned within or adjacent to evaporator chambers, and multiple effect stages are vertically or horizontally integrated. This nesting minimizes the overall footprint by eliminating intermediate spacing and allowing heat transfer surfaces to serve dual purposes.
3Use of energy by moving object
If RO systems are used for desalination, then energy consumption is reduced (no heating required), but TDS removal efficiency decreases (75-98% vs 99% for thermal systems)
Solution Approach 1:
The system maintains continuous phase change action across multiple effect stages, with vapor from one effect immediately condensing in the next. This continuous cascaded process maximizes purification efficiency by subjecting water to repeated phase change cycles, achieving near-complete contaminant removal while recovering heat at each stage.
4Ease of manufacture
If RO systems are used for desalination, then capital cost is reduced, but operational complexity increases due to pre- and post-treatment requirements and membrane fouling management
Solution Approach 1:
The system uses phase transition (evaporation and condensation) as the primary separation mechanism, which inherently rejects all non-volatile contaminants including salts, organics, and particulates. This physical mechanism eliminates the need for membrane filtration and associated pre-/post-treatment processes, simplifying operation while maintaining high purification efficiency.
5Use of energy by moving object
If RO systems are used for desalination, then energy consumption is reduced, but concentrate disposal problems increase due to large volume of poorly quality waste
Solution Approach 1:
The system recovers heat from the condensation process in each effect stage and uses it to preheat feedwater or drive subsequent effects, maximizing energy utilization. The concentrated brine is discharged at progressively lower temperatures across effects, reducing its thermal energy and making disposal more environmentally acceptable while minimizing water loss.
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 solution effectively recovers clean water from contaminated sources with low capital and maintenance costs, a small footprint, and reduced ecological impact, achieving high water purity and destroying organic contaminants, while also addressing the disposal issues of RO concentrate.
Implementation Method 1
The internal pressure of the sealed flash vessel is reduced by passing a high-pressure stream through a Venturi-type differential pressure injector that 'pulls' a vacuum in the flash vessel until the water's boiling point has been lowered to preferably about 76 degrees Fahrenheit.
Implementation Method 2
The contaminated water is then made to function as an electrolytic solution by passing an alternating current through it. One or more heat sources, preferably an electrical heating element, may be connected to one of the plates to provide the circuit load. The heat source is positioned within the flash vessel to further heat the contaminated water.
Implementation Method 3
The evaporated water condenses, as distilled water, at the top of the flash vessel and falls into a distilled water collection trough.
Implementation Method 4
A method and apparatus using multiple-effect vacuum distillation with electrical heating to evaporate and condense water at lower temperatures
Data Source
AI summary
Contaminated water stored in an equalization basin is distributed to one or more flash vessels and a desired vacuum is pulled in a filled flash vessel, reducing the boiling point of the contained contaminated water. The suction force is preferably created by passing the contaminated water under pressure through a differential pressure injector. The contaminated water in the flash vessel completes an electrical circuit between conductive plates and a heating element that are submerged therein. An alternating electrical current is applied, some of which is conducted by the contaminated water to a heating element that heats the water, and the rest of which dissipates as thermal energy, heating the contaminated water. The alternating current is preferably generated by passing the contaminated water under pressure through a hydroelectric power generator. Little thermal energy is needed to evaporate the contaminated water, which condenses at the top of the flash vessel and is collected from a collection trough. Slurry created by distillation is delivered to the equalization basin to increase the conductivity and temperature of the stored contaminated water.