Rotary Filter Precoat Removal via Reverse Rotation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for precoat removal in rotary filters, such as disc and drum filters, are inefficient and costly, leading to clogging, high water usage, and dilution of lime sludge, which disrupts the filtration process and downstream operations, especially when dealing with lime sludge in the chemical pulping industry.
Innovation Solution
A method and apparatus where water sprays are directed sloping downwards against the normal rotational direction of the filter to efficiently remove the precoat, minimizing liquid leakage into the basin and allowing for simultaneous cleaning of the filtering surface, reducing the need for frequent filter stops and minimizing water usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If liquid sprays are directed above the scraper to remove precoat, then precoat removal efficiency is improved, but liquid leaks into the basin causing dilution of lime sludge
Solution Approach 1:
The filter surface rotation direction is inverted during precoat removal, rotating opposite to the normal filtering direction. This inversion causes the precoat to be pushed toward the scraper by the spray while the filter surface moves against the spray direction, preventing liquid leakage into the basin and avoiding dilution of the lime sludge.
2Productivity
If powerful liquid sprays are used to remove precoat, then precoat removal efficiency is improved, but water consumption increases
Solution Approach 1:
The rotation direction parameter of the filter surface is changed during precoat removal operation. By rotating the filter surface opposite to the normal filtering direction, the spray liquid is forced to act against the moving surface, dramatically improving removal efficiency with minimal water consumption and eliminating the need for powerful sprays.
3Productivity
If the filter operates continuously without precoat removal, then productivity is maintained, but the filter gets clogged and reliability decreases
Solution Approach 1:
The filter operates in periodic cycles, alternating between normal filtering operation and brief precoat removal phases. During precoat removal, the filter surface rotates opposite to the normal direction while liquid spray is applied, efficiently clearing the precoat in a short time. This periodic action prevents clogging and maintains long-term reliability while minimizing interruptions to productivity.
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 enables efficient precoat removal with minimal liquid and pressure, reducing operational disturbances, extending the time between filter maintenance, and maintaining solution concentration, thereby enhancing filtering capacity and reducing the need for repeated filtration.
Implementation Method 1
water sprays are directed sloping downwards against the normal rotational direction of the filter to efficiently remove the precoat
Data Source
AI summary
A method associated for treating a precoat on a rotating filtering surface of lime sludge filter including: accumulating a precoat of lime sludge on the filtering surface by rotating the filtering surface in a first direction through a lime sludge slurry; after accumulating the precoat, rotating the filtering surface in an opposite direction to the first direction; while rotating the filtering surface in the opposite direction, spraying a liquid onto the precoat on the filtering surface wherein the spraying is applied to the precoat above a scraper adjacent the filtering surface and the spraying removes at least a portion of the precoat from the filtering surface, and flowing the removed precoat over the scraper and into a basin.