Multi-Stage Reverse Osmosis for Boric Acid Separation
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Solution Overview
Problem
Current membrane treatment techniques for separating boric acid from nuclear power plant effluents fail to achieve the required concentrations of concentrated boric acid and purified water due to low boron rejection rates and fluctuations in effluent supply, leading to high energy consumption and significant investment costs.
Innovation Solution
A multi-stage reverse osmosis process using membranes with high boron rejection rates, arranged in parallel and series, and recycling intermediate products to achieve the desired concentrations of 7500 mgB/L boric acid and <5 mgB/L purified water, employing membranes with selectivity towards boron and optimizing the process architecture to handle fluctuating feed concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional reverse osmosis membranes are used for boric acid separation, then the process structure is simple, but the boron rejection rate is low and required concentrations cannot be achieved
Solution Approach 1:
The system divides the separation process into multiple stages with different membrane types. First stage uses conventional RO membranes for initial concentration, second stage uses nanofiltration membranes for further concentration, and third stage uses evaporation for final concentration. This segmentation allows each stage to be optimized for its specific function, achieving high boron rejection rates while managing complexity through modular design.
2Reliability
If thermal evaporation process is used, then mature technology and reliable operation are achieved, but facility size is large and energy consumption is high
Solution Approach 1:
The system segments the concentration process into multiple stages combining membrane separation and evaporation. Membrane processes handle initial and intermediate concentration with low energy consumption, while evaporation is used only for final concentration. This reduces overall energy consumption compared to using evaporation throughout, while maintaining reliability through proven membrane technologies and controlled evaporation operations.
Solution Approach 2:
The system changes operating parameters at different stages: membrane processes operate at ambient or moderate temperatures with controlled pressure, while evaporation operates at elevated temperatures only when necessary for final concentration. This parameter optimization reduces energy consumption while maintaining operational stability and achieving required concentration levels.
3Use of energy by stationary object
If multi-stage membrane process with recycling is implemented, then energy consumption is reduced and compactness is improved, but process complexity increases
Solution Approach 1:
The system implements recycling loops where concentrate from one stage is fed back to the previous stage, and permeate is recycled to optimize separation efficiency. This feedback mechanism allows the system to achieve high energy efficiency and compact design by maximizing the utilization of each stage's output, while the modular structure manages complexity through standardized recycling configurations.
4Manufacturing precision
If high concentration of boric acid is achieved, then purified water production is improved, but process complexity and investment costs increase
Solution Approach 1:
The system achieves high boric acid concentration through segmented stages: first stage RO membranes concentrate from dilute to intermediate levels, second stage nanofiltration membranes further concentrate to high levels, and third stage evaporation achieves very high concentrations. This segmentation allows each stage to be optimized for its concentration range, achieving high overall concentration while managing facility complexity and investment costs through modular design.
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 process achieves high boron rejection rates (>80%), efficiently producing concentrated boric acid and purified water, reducing energy consumption and investment costs while improving compactness and flexibility compared to traditional thermal processes.
Implementation Method 1
separation of boric acid from the primary circuit water of a nuclear power plant
Implementation Method 2
multi-stage assembly composed of reverse osmosis modules having a membrane with a high boron rejection rate
Implementation Method 3
A multi-stage reverse osmosis process using membranes with high boron rejection rates, arranged in parallel and series
Implementation Method 4
achieve the desired concentrations of 7500 mgB/L boric acid and <5 mgB/L purified water
Implementation Method 5
separation of boric acid from the primary circuit water of a nuclear power plant
Implementation Method 6
membrane with a high boron rejection rate
Data Source
AI summary
The present invention relates to a process for treating aqueous effluents from the primary circuit of a nuclear power plant implementing a separation of boric acid using a reverse osmosis membrane, characterized by the fact that it comprises steps consisting of treating the effluents using a multi-stage assembly composed of reverse osmosis modules comprising a membrane with a high boron rejection rate, arranged in parallel and in series, and recycling of the intermediate products to different points in the assembly.