Removable Rejects Chamber for Pressure Screen Maintenance
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Solution Overview
Problem
Existing screens for pulp and fiber web production, particularly those handling recycled fibers, face significant downtime and wear issues due to the need for extensive disassembly and replacement of the rejects chamber, leading to increased maintenance time and reduced equipment lifespan.
Innovation Solution
The design features a removable rejects chamber with a cast dished cover and hydrodynamic anti-wear vanes, along with a wear-resistant coating, allowing for in-field replacement and reduced wear, thereby minimizing shutdown duration and enhancing equipment safety and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the rejects chamber is made as a welded fabricated section or cast dished chamber, then the screen structure is strong and durable, but the maintenance time increases significantly due to extensive disassembly work required
Solution Approach 1:
The screen is divided into separable modules: the rejects chamber is made as a distinct removable component that can be detached from the screen body without extensive disassembly. This segmentation allows the rejects chamber to be replaced independently, significantly reducing maintenance shutdown time while maintaining the structural integrity of the overall screen system.
Solution Approach 2:
The rejects chamber is extracted as a separate removable component from the integrated screen structure. By making it detachable through reopeningable attachment means, the rejects chamber can be taken out for repair or replacement without dismantling the entire screen, thus resolving the contradiction between structural strength and maintenance time.
2Stability of the object's composition
If the rejects chamber is welded in place, then the structural integrity is maintained, but the repair complexity increases and requires significant disassembly work
Solution Approach 1:
The screen structure is segmented into modular components with the rejects chamber as a separate unit. This segmentation maintains structural integrity through proper connection design while enabling easy removal and repair of the rejects chamber without significant disassembly work.
Solution Approach 2:
The attachment means between the rejects chamber and screen body are designed to be dynamically changeable between closed (secured) and open (removable) states. This dynamic design allows the rejects chamber to be firmly attached during operation for structural integrity, yet easily removed for repair when needed.
3Reliability
If the screen is replaced for repair work, then the structural integrity is preserved, but the productivity decreases due to complete replacement
Solution Approach 1:
The screen system is segmented into replaceable modules, specifically the rejects chamber. This allows only the worn component to be replaced rather than the entire screen, maintaining equipment reliability while minimizing production downtime and preserving productivity.
Solution Approach 2:
Instead of replacing the entire screen when the rejects chamber wears, the design enables discarding only the worn rejects chamber component and recovering the rest of the screen system. This selective replacement approach maintains reliability while significantly improving productivity by reducing replacement time and cost.
4Duration of action of stationary object
If the rejects chamber surfaces wear due to recycled fiber material, then the equipment lifespan reduces, but extensive disassembly is required for repair
Solution Approach 1:
The rejects chamber is segmented as a separate removable component with lining that can be independently replaced. This segmentation extends equipment lifespan by allowing easy replacement of worn surfaces without complex disassembly, thereby resolving the contradiction between lifespan and disassembly complexity.
Solution Approach 2:
The rejects chamber lining is designed as a replaceable component that can be economically replaced when worn. This approach extends the overall equipment lifespan by allowing easy renewal of the wear-prone surfaces without requiring complex repairs, while the simplicity of replacement offsets the increased device complexity.
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 solution enables quicker maintenance, extended screen lifespan, reduced wear, and improved hydraulic efficiency by facilitating field replacement of the rejects chamber and utilizing anti-wear features to manage flow and minimize wear at critical areas.
Implementation Method 1
the rotor is used to fluidize the pulp slurry on the inner diameter of the basket
Implementation Method 2
The rejects chamber of the screen comprises at least one hydrodynamic anti-wear vane attached on an inner wall of the rejects chamber at a distance from the light rejects outlet. The hydrodynamic anti-wear vane/-s guide the flow inside the rejects chamber hydrodynamically such that the particles of the reject flow causing wear are guided off from that/those surface part/-s that are susceptible to wear.
Implementation Method 3
at least one surface in an immediate vicinity of the light rejects outlet provided with a wear resistance coating
Data Source
AI summary
A pressure screen for use in a fiber web product process (10) has an inlet zone (12), a basket having an accept zone (14) and a reject zone (20). The pressure screen (10) has a housing (28) inside which a rotor (27) is located. The reject zone (20) of the pressure screen (10) has a cover (22) forming a rejects chamber (21) for the reject zone (20). The cover (22) of the rejects chamber (21) of the screen (10) is removable by a reopenable attachment means (25, 29) attached to the housing (28) of the screen (10).