Multi-Stage Bubble-Column Condenser for Low-Scale Desalination
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Solution Overview
Problem
Current seawater desalination technologies are energy- and capital-intensive, with inefficiencies in heat transfer and energy recovery, leading to high costs and environmental concerns due to the formation of hard scale in heat transfer equipment.
Innovation Solution
A multi-stage bubble-column vapor mixture condenser system that uses a carrier gas to enhance heat transfer and energy recovery, reducing thermal resistance and energy costs by employing a novel multi-staging technique and direct heat recovery, while maintaining high heat-transfer coefficients comparable to film condensation of steam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If reverse osmosis is used for desalination, then fresh water can be produced from seawater, but massive amounts of energy are required
Solution Approach 1:
The condensation process is divided into multiple stages with progressively lower temperatures. The carrier gas passes through sequential condenser stages, allowing vapor to condense at different temperature levels. This segmentation enables efficient heat recovery by matching the temperature gradient between the carrier gas and cooling media, significantly reducing the overall energy required for desalination compared to single-stage systems.
Solution Approach 2:
The system implements heat recovery feedback by using the cooling media that absorb heat from condensing vapor to preheat the brine feed or to cool the carrier gas in subsequent stages. This feedback loop recovers thermal energy that would otherwise be wasted, reducing the total energy input needed for the desalination process and improving overall system efficiency.
2Quantity of substance
If thermal-energy-based multi-stage flash or multi-effect distillation is used, then desalination can be achieved, but the processes are energy- and capital-intensive
Solution Approach 1:
An inert carrier gas (such as air or nitrogen) is introduced as an intermediary medium to transfer heat from the brine to the condensing vapor. The carrier gas absorbs heat from the hot brine in the humidifier and delivers it to the vapor in the condenser stages, enabling efficient heat exchange without direct thermal contact between brine and cooling water. This intermediary approach reduces thermal energy consumption by minimizing heat losses and improving heat transfer efficiency.
3Productivity
If MSF and MED systems operate at high temperatures, then evaporation rate increases, but calcium sulphate precipitation forms hard scale on heat transfer equipment
Solution Approach 1:
The carrier gas serves as an intermediary that enables heat transfer without direct contact between hot brine and cooling surfaces. By using gas-phase heat transfer in the condenser stages, the system avoids the scale formation problems associated with liquid-to-surface heat transfer in traditional MSF and MED systems, allowing operation at temperatures that maximize evaporation rates without calcium sulphate precipitation on heat transfer equipment.
4Power
If direct-contact condenser is used, then heat transfer rates increase, but energy from humid air is not recovered to preheat seawater
Solution Approach 1:
The condensation process is divided into multiple stages with progressively lower temperatures. The carrier gas passes through sequential condenser stages, allowing vapor to condense at different temperature levels. This segmentation enables efficient heat recovery by matching the temperature gradient between the carrier gas and cooling media, significantly reducing the overall energy required for desalination compared to single-stage systems.
Solution Approach 2:
The system implements heat recovery feedback by using the cooling media that absorb heat from condensing vapor to preheat the brine feed or to cool the carrier gas in subsequent stages. This feedback loop recovers thermal energy that would otherwise be wasted, reducing the total energy input needed for the desalination process and improving overall system efficiency.
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 achieves significant reductions in energy and equipment costs, with improved heat recovery and efficiency in producing fresh water from seawater, brackish water, or wastewater, addressing the inefficiencies of existing desalination methods.
Implementation Method 1
The carrier-gas inlet is positioned to bubble carrier gas from the carrier-gas inlet up through the condensing bath, overcoming a hydrostatic head of the condensing bath
Implementation Method 2
Multi-stage bubble-column vapor mixture condenser
Data Source
AI summary
A multi-stage bubble-column vapor mixture condenser comprises at least a first stage and a second stage. Each stage includes a carrier-gas inlet and a carrier-gas outlet, as well as a condenser chamber containing a condensing bath in fluid communication with the carrier-gas inlet and the carrier-gas outlet. The carrier-gas inlet is positioned to bubble carrier gas from the carrier-gas inlet up through the condensing bath, overcoming a hydrostatic head of the condensing bath. The carrier-gas outlet is positioned with an opening for carrier-gas extraction above the condensing bath, wherein the first-stage carrier-gas outlet is in fluid communication with the carrier-gas inlet of the second stage to facilitate flow of the carrier gas through the condensing bath in the condenser chamber of the first stage and then through the condensing bath in the condenser chamber of the second stage.