Walnut Shell Garnet Filtration Backwashing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional filtration systems for oil field water, which rely on particulate media, face challenges in maintaining the optimal layer structure after backwashing, leading to inefficient removal of oil droplets and suspended solids, and require media removal for washing, increasing operational complexity and costs.
Innovation Solution
A filtration arrangement using a vessel with an upper layer of crushed walnut shells and a lower layer of garnet, supported by a coarser garnet layer, where the media is backwashed with a mixture of gas and liquid to maintain the optimal structure and prevent blockages, allowing for in-vessel cleaning without media removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional filtration media is backwashed by passing fluid backwards through it, then the media bed becomes fluidised and contaminant material is scrubbed off, but the coarser particles settle at the bottom and finer particles at the top, reversing the optimal layer structure
Solution Approach 1:
The patent applies inversion by reversing the conventional backwashing approach. Instead of simply passing fluid backwards through the media bed, the invention introduces gas (air) from below at sufficient pressure to lift and fluidise the entire media bed, causing particles to become suspended and redistributed. This inverted approach allows the media to self-reorganize into the correct configuration (coarser particles at top, finer at bottom) based on density and size gradients during the fluidisation process, rather than settling into the reversed configuration that occurs with conventional liquid-only backwashing.
Solution Approach 2:
The patent changes the physical parameters of the backwashing process by introducing gas phase flow in addition to or instead of liquid phase flow. This parameter change (from liquid-only to gas-liquid or gas-phase backwashing) fundamentally alters the fluidisation characteristics of the media bed, enabling proper particle redistribution and layer reformation. The gas flow rate and pressure are controlled to achieve optimal fluidisation without destroying the media structure.
2Ease of manufacture
If media is removed from the filtration vessel for washing, then thorough cleaning can be achieved, but operational complexity and costs increase
Solution Approach 1:
The patent enables the filtration media to clean itself through in-vessel backwashing without requiring removal from the vessel. The gas-fluidised backwashing process allows contaminant material to be scrubbed off and floated off within the same vessel, making the system self-sufficient. This eliminates the need for external washing equipment, media handling infrastructure, and associated operational complexity, while still achieving effective cleaning.
Solution Approach 2:
The invention merges the filtration function and the washing function into a single vessel and operational cycle. The same vessel that performs filtration also performs backwashing and media reformation, eliminating the need for separate washing equipment or media removal procedures. This consolidation reduces device complexity, operational steps, and costs while maintaining cleaning effectiveness.
3Device complexity
If a single layer of filtration media is used, then the structure is simple, but it cannot effectively remove both oil droplets and suspended solids with different size requirements
Solution Approach 1:
The patent segments the filtration media into distinct layers with different particle sizes and densities: a top layer of coarser material (e.g., nutshells) for removing larger contaminants like oil droplets, and a bottom layer of finer material (e.g., garnet) for removing suspended solids. This segmentation allows each layer to specialize in removing specific types of contaminants, significantly improving overall filtration efficiency while maintaining a relatively simple multi-layer structure.
Solution Approach 2:
The invention applies local quality by giving different regions of the media bed different properties - the upper layer has coarser particles suited for oil droplet removal, while the lower layer has finer particles suited for suspended solid removal. This spatial variation in media properties optimizes the filtration performance at each level of the bed, allowing simultaneous effective removal of different contaminant types.
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 configuration effectively removes oil droplets and suspended solids in a single process, allows for efficient backwashing within the vessel, and maintains the optimal media structure, reducing operational complexity and costs compared to prior methods.
Implementation Method 1
The gas may be fed into the vessel to cause turbulence in the media, and may be fed into the vessel at such a high volume so as to create agglomerations or 'slugs' of gas which rise through the vessel
Implementation Method 2
Following filtration the particulate material bed may be washed by passing fluid backwards therethrough, and then allowing the layers in the particulate material bed to settle
Implementation Method 3
Media filtration is often used for such cleaning, where the water is passed downwardly through a particulate filtration media
Implementation Method 4
Water to be filtered will enter through the inlet 14 and be distributed across the vessel 12 by the pipes 20. Water will pass into the walnut shell layer 28 which has been found to be highly effective at adsorbing and/or absorbing oil droplets in the water
Data Source
Figure 1
Figure 2
AI summary
A filtration arrangement (10) including a closed pressure vessel (12) with an upper inlet (14) and a lower outlet (16). A particulate filter media (26) is provided in the vessel (12) with an upper layer (28) of walnut shell for oil removal, a finer garnet layer (30) for solids removed, and a coarser garnet support layer (32). The filtration arrangement is to be used in particular for filtering water produced in an oil field. The particulate filter media (26) is backwashed by passid fluid (liquid and/or gas) through the filtration arrangement.