Backflush Filter with Segmented Zones for Low Liquid Consumption
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Solution Overview
Problem
Existing backwash filter systems are inefficient in handling high solids content and fine particles, leading to excessive backwash liquid consumption and incomplete cleaning due to design limitations, particularly in cake-forming filtration processes.
Innovation Solution
A filtration process and apparatus utilizing a cylindrical housing with a perforated support body and filter material with high air permeability, allowing rapid filter cake formation and efficient backwashing, along with the use of filter aids and a sliding member for sealing to prevent bypass flows, enabling effective separation of fine and greasy particles and reducing backwash liquid requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the suction nozzle is positioned at a large distance from the filter fabric to allow large particles to enter, then large particles can be discharged, but bypass flows occur causing backwash liquid losses and requiring more backwash liquid than available filtrate
Solution Approach 1:
The filter element is divided into multiple segments or zones with different nozzle distances from the filter fabric. Some zones have nozzles positioned closer to the fabric while others are farther, allowing particles of different sizes to be discharged from different zones. This segmentation enables effective large particle discharge while minimizing bypass flows and backwash liquid consumption in other zones.
2Reliability
If backwash liquid is drained through the entire filter cartridge during cleaning, then all particles can be removed, but large quantities of backwash liquid are required that exceed available filtrate
Solution Approach 1:
Different zones of the filter element have different backwash characteristics. Zones with larger particle retention require more backwash liquid and are cleaned more thoroughly, while zones with smaller particles require less backwash liquid. This local differentiation of cleaning intensity matches the actual contamination distribution, achieving reliable cleaning where needed while conserving backwash liquid in other areas.
3Productivity
If filter material with high air permeability is used to enable rapid filter cake formation, then filtration speed increases, but fine particle separation becomes more difficult
Solution Approach 1:
Coarse particles are filtered and retained first to form a pre-filter layer or filter cake on the filter material. This preliminary action creates a secondary filtration barrier that enhances fine particle separation without requiring the filter material itself to have extremely fine pores. The pre-formed cake layer provides the fine separation function while the underlying high-permeability filter material maintains high filtration speed.
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 solution enables rapid filter cake formation, low backwash liquid consumption, and high filtration speed, ensuring effective filter cleaning and operation even with high solid concentrations, while minimizing filter aid usage and regeneration time.
Implementation Method 1
the filter material consist of a filter fabric having an air permeability of 700-1300 l/m2s at a pressure differential of 200 Pa
Implementation Method 2
sealing of the unfiltrate chamber 6 toward the reject chamber 4 is accomplished by a pressed-on sliding member 3
Data Source
AI summary
The invention relates to a process for filtration of fluids, especially of aqueous media, by means of a backflush filter apparatus consisting of a cylindrical housing, a cylindrical and perforated support body installed coaxially therein, a filter material, a support fabric, and a mobile backflush device present therein, said process enabling improved removal of fine and ultrafine particles, and of particles with greasy or compressible consistency, and allowing higher solid concentrations. The process according to the invention has the steps below. a) Formation of a filtercake in the perforation of the support body; b) deposition of the relatively fine particles or of the particles with greasy or compressible consistency on or in the filtercake; c) backflushing after attainment of the predefined filter loading or of the maximum permissible pressure differential, or when the filtrate volume flow goes below a minimum. A further aspect of the invention is a filter apparatus for performance of the process, characterized in that the filter material consists of a filter fabric with an air permeability of 700-1300 l/m2s at pressure differential 200 Pa.