Active Grate Rocker Mechanism for Gasification Material Flow
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Solution Overview
Problem
Existing grate systems in high temperature partial oxidation gasification systems face issues with material blockage and uneven oxidation, leading to inefficient transfer of materials from the gasification unit to the vitrification unit, as certain materials tend to plug the grate, causing uneven gas flow and oxidation rates.
Innovation Solution
An active grate with rotating elongated rockers, each configured to rotate back and forth about its longitudinal axis, forming voids to allow material passage and closing to crush larger pieces, ensuring regular flow and size reduction, and incorporating a coolant loop to manage high temperatures and reduce wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional stationary grate systems are used for material transfer, then structural simplicity is maintained, but material flow uniformity deteriorates causing blockages and uneven oxidation
Solution Approach 1:
The patent applies the dynamics principle by transforming the stationary grate into a moving grate system where the grate surface continuously moves through the combustion chamber. This movement prevents material accumulation and blockages while ensuring uniform distribution of feedstock across the grate surface, thereby improving material flow uniformity without requiring complex mechanical structures beyond the drive mechanism at one end.
Solution Approach 2:
The moving grate is segmented into multiple parallel bars or segments that can move independently or in coordinated fashion. This segmentation allows material to flow between the gaps while the overall grate structure moves forward, preventing clogging and ensuring even oxidation across different zones of the combustion chamber.
2Productivity
If grate speed is increased to improve material transfer rate, then productivity increases, but material residence time decreases leading to incomplete combustion
Solution Approach 1:
The grate system implements local quality by varying the movement speed or direction in different zones of the combustion chamber. The feed zone may have slower movement to allow proper ignition and initial combustion, while the intermediate zones maintain optimal speeds for sustained burning, and the discharge zone accelerates to prevent ash accumulation. This zoned approach ensures complete combustion while maintaining high overall productivity.
Solution Approach 2:
The grate employs periodic reversal or oscillation movements where the grate surface moves forward to advance material, then reverses or pauses to allow thorough combustion of materials that may be slowing down or stopping. This periodic action pattern ensures that even at high average speeds, materials receive sufficient residence time for complete combustion before being discharged.
3Productivity
If grate surface area is increased to handle larger material volumes, then processing capacity improves, but device complexity and space requirements increase
Solution Approach 1:
The patent transitions from a two-dimensional stationary grate surface to a three-dimensional moving grate system that progresses through the combustion chamber along the longitudinal axis. This dimensional change allows the same grate surface area to process much larger volumes of material over time by continuously advancing through the chamber, effectively increasing processing capacity without proportionally increasing the physical footprint or structural complexity.
Solution Approach 2:
The moving grate serves multiple functions simultaneously: it conveys material forward, distributes material uniformly across the combustion zone, controls residence time through speed regulation, and facilitates ash removal. This multi-functionality allows a single integrated structure to handle large material volumes without requiring additional separate systems, thereby increasing processing capacity while limiting the increase in overall 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
The active grate effectively agitates and crushes materials, ensuring a controlled and even flow from the gasification unit to the vitrification unit, preventing blockages and maintaining consistent oxidation, thereby enhancing the efficiency of the gasification and vitrification process.
Implementation Method 1
incorporating a coolant loop to manage high temperatures and reduce wear
Implementation Method 2
each with a curved lower surface and angled upper surface, alternately forming voids to facilitate material flow and crush large pieces
Data Source
AI summary
An improved active grate consisting of at least two elongated rockers positioned parallel to one and another, each rocker having a lower surface and an upper surface and configured to rotate back and forth about their longitudinal axis. Each individual rocker is further configured to rotate in the opposite direction of the adjacent rockers such that any pair of adjacent rockers alternately forms a void allowing material to pass through active grate when rotating in one direction into a first position, and closes the void when rotated in the opposite direction in a second position. The active grate finds particular utility in a combined gasification/vitrification waste treatment system, where it is used to pass partially oxidized materials from a gasification chamber to a vitrification chamber. The rockers include a coolant loop through the longitudinal axis of the rockers.