Bottom Ash Feed Regulation Using Variable-Speed Crusher Control
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Solution Overview
Problem
Existing bottom ash processing systems face challenges in achieving a high turndown ratio due to varying capacities among subsystems, leading to bottlenecks and arching issues, particularly when using low capacity conveyors in continuous operations.
Innovation Solution
A system incorporating a variable speed side discharge crusher and fixed flow restrictors, such as an orifice plate or extended wear plate, to control ash flow without relying on a bottom gate, combined with a conveyor signal-based control scheme to prevent overfeeding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a bottom gate is used to control ash flow, then flow control is achieved, but arching occurs and requires frequent adjustments
Solution Approach 1:
The patent removes the bottom gate from the system entirely, extracting the flow control function from the hopper discharge and relocating it to the conveyor system. This eliminates the arching problem caused by bottom gates while maintaining flow control capability through alternative means.
Solution Approach 2:
The conveyor system serves as an intermediary between the hopper and the discharge point, providing flow control through its own mechanisms rather than relying on a bottom gate. The conveyor's ability to regulate its own feed rate acts as the mediating flow control mechanism.
2Productivity
If a low capacity conveyor is used, then processing capacity is reduced, but turndown ratio is improved
Solution Approach 1:
The conveyor system is made dynamically controllable through variable speed drives and feedback control mechanisms. This allows the conveyor to adjust its capacity continuously to match the hopper's discharge rate, achieving high turndown ratios while maintaining operational flexibility.
Solution Approach 2:
A feedback control system monitors the conveyor's load and adjusts its speed accordingly, ensuring optimal operation across a wide range of flow conditions. This feedback mechanism enables the low capacity conveyor to handle variable loads efficiently, improving turndown ratio while maintaining productivity.
3Productivity
If bottom gate is partially closed to control flow, then overfeeding is prevented, but larger particles block the gate increasing arching risk
Solution Approach 1:
By removing the bottom gate entirely, the patent eliminates the problem of larger particles blocking the gate. Flow control is achieved through the conveyor system's inherent capacity to regulate its own feed rate, avoiding the particle blocking issue associated with partial gate closure.
Solution Approach 2:
The system changes the control parameter from gate opening degree to conveyor speed. This parameter change allows flow control to be achieved without partially closing a gate, thereby preventing larger particles from blocking the discharge point and reducing arching risk.
4Reliability
If bottom gate is opened to clear arch, then flow is restored, but overfeeding occurs leading to further arching
Solution Approach 1:
By extracting the flow control function from the bottom gate and placing it in the conveyor system, the patent eliminates the cycle of opening the gate to clear arch and then closing it to prevent overfeeding. The conveyor's self-regulating capability prevents overfeeding while maintaining flow.
Solution Approach 2:
The conveyor system performs self-service flow control, automatically regulating its own feed rate based on actual conditions. This self-service capability eliminates the need for manual gate adjustments and prevents the arching-overfeeding cycle by maintaining optimal flow conditions continuously.
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
Enables continuous operation with improved turndown ratio, reduces arching, and minimizes wear on system components by optimizing flow control through the crusher and conveyor.
Implementation Method 1
fixed flow restrictors, such as an orifice plate or extended wear plate, to control ash flow
Implementation Method 2
variable speed side discharge crusher
Implementation Method 3
conveyor for removing and/or dewatering the ash
Data Source
AI summary
A system and mechanism for bottom ash flow turndown from a hopper, through a crusher, and to a conveyor, the system including a fixed flow restrictor and a variable speed side discharge crusher to modulate bottom ash flow in the absence of gate or valve flow from a hopper, the conveyor providing a signal corresponding to an overfeed condition to enable a controller to operate the crusher and/or the conveyor to eliminate overfeed conditions.