Alternating Flow Filter for Produced Water Fouling
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Solution Overview
Problem
Current filtration systems, such as cross-flow microfiltration, struggle to achieve low hydrocarbon levels of 10 to 15 mg/l in produced water efficiently and economically, often resulting in high capital and operating costs, and are prone to fouling layer formation and irreversible blockages, which impairs their performance.
Innovation Solution
A method involving alternating forward and reverse fluid flow directions through filter elements, with a cross-flow bleed stream velocity of no more than 4m/s and a volume of at least 5% of the total fluid, promoting the formation of a fouling layer to enhance filtration efficiency, and using filter elements with pore sizes of no less than 4 microns to combine filtration with the fouling layer for effective contaminant removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cross-flow microfiltration is used to filter contaminants from produced water, then filtration is achieved, but the system is prone to fouling layer formation and irreversible blockages which impairs performance
Solution Approach 1:
The patent implements periodic flow direction reversal, alternating between forward flow (filtration mode) and reverse flow (cleaning mode). During forward flow, contaminants are filtered from the feedstream. During reverse flow, the accumulated fouling layer is removed by flushing with cleaning fluid. This periodic action prevents irreversible blockages and maintains filtration performance over extended operational periods.
Solution Approach 2:
The patent discards the accumulated fouling layer during reverse flow cycles by flushing it away with cleaning fluid through the filter element. This allows the filter to recover its full filtration capacity and continue operation without permanent performance degradation, effectively discarding the harmful fouling accumulation.
2Manufacturing precision
If smaller pore sizes are used in filter elements to achieve lower hydrocarbon levels, then filtration efficiency improves, but throughput decreases and operating costs increase
Solution Approach 1:
The patent uses dynamically adjustable flow rates during both forward and reverse flow cycles, allowing optimization of the balance between filtration efficiency and throughput. The system can adapt flow parameters to maintain high productivity while achieving required hydrocarbon reduction levels.
Solution Approach 2:
The automated alternating flow system enables continuous operation with minimal downtime. The rapid transition between filtration and cleaning modes ensures that the filter element remains productive throughout the cycle, maintaining high overall throughput while achieving low hydrocarbon levels in the filtrate.
3Productivity
If conventional filtration systems operate continuously, then productivity is maintained, but fouling accumulates and requires shutdown for cleaning
Solution Approach 1:
The system maintains continuous productive action by integrating cleaning function into the operational cycle itself. The rapid automated reversal between forward and reverse flow allows cleaning to occur during what would otherwise be downtime, effectively eliminating idle time and maintaining continuous productivity.
Solution Approach 2:
The periodic flow reversal creates regular cleaning intervals that prevent fouling accumulation to problematic levels. This proactive periodic cleaning approach minimizes the frequency and duration of shutdowns, maintaining high overall productivity while preventing performance degradation.
4Reliability
If high cross-flow velocity is used to prevent fouling layer formation, then filtration performance is maintained, but energy consumption and system complexity increase
Solution Approach 1:
Instead of maintaining continuously high cross-flow velocity to prevent fouling, the system uses periodic reverse flow pulses for cleaning. This allows most of the time to be spent in efficient forward filtration mode at lower energy consumption, with brief cleaning intervals removing accumulated fouling, thereby reducing overall energy requirements while maintaining performance.
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 approach reduces downtime, improves filtration efficiency, and increases throughput while preventing irreversible fouling, achieving low hydrocarbon levels and reducing operational costs by utilizing larger pore sizes and a controlled fouling layer for effective contaminant removal.
Implementation Method 1
a filter element arranged to filter contaminants from a feedstream of a fluid directed into the filter chamber
Implementation Method 2
arranging at least part of the feedstream fluid directed into the filter chamber to flow in one of: A. a forward flow direction where the fluid passes in a first direction through a wall of the filter element; and B. a reverse flow direction where the fluid passes in a second, opposite direction through the wall of the filter element
Data Source
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AI summary
The invention relates to methods of filtering contaminants from a fluid, to a filter module for filtering contaminants from a fluid, and to a filtration plant comprising at least one such filter module. In one embodiment, a method of filtering contaminants from a fluid is disclosed which comprises the steps of: directing a feedstream of a fluid containing contaminants into a filter chamber (14a) containing at least one filter element (18a); arranging at least part of the feedstream fluid directed into the filter chamber to flow in one of: A) a forward flow direction where the fluid passes in a first direction through a wall (22a) of the filter element; and B) a reverse flow direction where the fluid passes in a second, opposite direction through the wall of the filter element. The method further comprises directing the filtrate out of the chamber and into a filtrate flowline (26) for collection; subsequently arranging the feedstream fluid directed into the filter chamber to flow through said filter element in the other one of the forward and reverse flow directions, to remove contaminant material from a surface of the wall of the element; following removal of said contaminant material by fluid flow in the other one of the forward and reverse flow directions, continuing to direct feedstream fluid through the wall of the filter element in said other direction to thereby filter out contaminants from the fluid during flow in said other direction; and subsequent to removal of said contaminant material, directing the filtrate resulting from flow through the wall of the filter element in said other flow direction out of the chamber and into the filtrate flowline for collection.