Electrodialysis Spacer Design for Stack Burning Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electrodialysis (ED) devices face issues such as stack burning and external leaks, especially at high temperatures, which limit their operating conditions and efficiency.
Innovation Solution
The ED device incorporates a membrane stack with alternating cation- and anion-exchange membranes and spacers with recessed and non-recessed areas, featuring a central opening and orifices to distribute liquid flow, thereby reducing shunt currents and preventing thermal damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If full-area ion exchange membranes are used in ED stacks, then the sealing area is improved, but shunt current passes through the sealing parts causing stack burning
Solution Approach 1:
The ion exchange membrane is designed with different properties in different areas: the active area maintains ion exchange functionality while the sealing area has reduced ion exchange capacity to minimize shunt current. This local differentiation allows the membrane to perform sealing function without causing stack burning, resolving the contradiction between sealing performance and harmful shunt current effects.
2Productivity
If operating voltage is increased to improve productivity, then desalination efficiency is improved, but thermal damage to the stack occurs
Solution Approach 1:
By creating a sealing area with reduced ion exchange capacity, the membrane directs current more efficiently through the active area, reducing overall resistive heating. This allows higher operating voltages to be applied without causing thermal damage, thus improving productivity while controlling temperature.
3Productivity
If the number of cell pairs in the stack is increased to improve productivity, then desalination capacity is improved, but the risk of stack burning increases
Solution Approach 1:
The modified membrane design with reduced ion exchange capacity in the sealing area can be applied to each cell in multi-cell stacks. This allows stacks with increased number of cell pairs to operate reliably without stack burning, as each cell's sealing area is optimized to minimize shunt current while maintaining sealing integrity.
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 design allows the ED device to operate at higher temperatures and under harsh conditions without risking membrane stack damage, while maintaining high efficiency and reducing external leaks.
Implementation Method 1
ED is used to transport salt ions from one solution (the diluate) through ion-exchange membranes to another solution (the concentrate), under the influence of an applied electric potential difference
Implementation Method 2
transport salt ions from one solution (the diluate) through ion-exchange membranes to another solution (the concentrate), under the influence of an applied electric potential difference
Implementation Method 3
The spacer 2.2, 2.4 is provided with at least four orifices 3.4, 3.5 within the non-recessed area 3.3; the spacer 2.2, 2.4 is provided with respective channels 3.6 which connect at least two of the orifices 3.4 with the central opening 3.1
Data Source
AI summary
The invention relates to an electrodialysis device for the desalination of water for oil and gas applications comprising: a membrane stack comprising alternating cation- and anion-exchange membranes (2.1, 2.3) and a plurality of spacers (2.2, 2.4), each spacer being arranged between two successive membranes; wherein at least one of the spacers (2.2, 2.4) comprises a recessed area (3.2) and a non-recessed area (3.3), a central opening (3.1) within the recessed area (3.2); the spacer (2.2, 2.4) is provided with at least four orifices (3.4, 3.5) within the non-recessed area (3.3); and with respective channels (3.6) which connect at least two of the orifices (3.4) with the central opening (3.1); and one membrane (2.1, 2.3) is accommodated in the recessed area (3.2).The invention also relates to a water desalination process using the electrodialysis device mentioned above.