Classifier Segmentation of Low-Grade Fuel in Cement Calciner
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Solution Overview
Problem
The cement clinker process faces challenges in efficiently utilizing low-grade fuels like packaging waste, which contains bulky and partially burnt combustible matter, requiring expensive preprocessing and inefficient energy transfer due to varying fuel sizes and weights.
Innovation Solution
A method and apparatus that classify low-grade fuels into a low weight fraction for direct combustion in the calciner and a high weight fraction for pyrolysis, using a tertiary air stream and a classifier with a collector to separate and process fuels based on weight/surface ratio, ensuring efficient energy transfer and reduced cooling needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If low grade fuels with varying sizes and weights are burned in the calciner, then energy cost is reduced, but combustion efficiency deteriorates due to inconsistent burning periods
Solution Approach 1:
The fuel stream is segmented into different size fractions using a classifier. Light fraction (smaller particles) and heavy fraction (larger particles) are separated and processed differently. This segmentation allows each fraction to be combusted in the most suitable location, maintaining combustion efficiency while using low-grade fuels with varying sizes.
Solution Approach 2:
A classifier acts as an intermediary device between the fuel supply and the calciner/kiln system. It sorts fuel particles by weight/surface ratio and directs them to appropriate combustion locations, enabling efficient utilization of mixed-size low-grade fuels without requiring expensive preprocessing.
2Adaptability or versatility
If bulky combustible matter is provided to the kiln, then fuel utilization is improved, but kiln process stability deteriorates
Solution Approach 1:
Bulky combustible matter is segmented by size using the classifier. Only the light fraction that can be properly transported and combusted is sent to the kiln, while the heavy fraction is separated out. This ensures that only appropriately sized fuel reaches the kiln, maintaining process stability while still utilizing bulky fuel sources.
Solution Approach 2:
Different quality requirements are applied to different fuel fractions. The light fraction receives full kiln processing, while the heavy fraction is handled separately. This local differentiation in processing quality allows bulky fuel to be utilized without compromising overall kiln stability.
3Power
If low grade fuel is burned in the reactor, then energy provision is improved, but device complexity increases due to required preprocessing
Solution Approach 1:
The classifier serves multiple functions: it classifies fuel by size, separates light and heavy fractions, and directs them to appropriate processing locations. This multi-functionality eliminates the need for separate preprocessing equipment, reducing device complexity while maintaining effective energy provision from low-grade fuels.
4Productivity
If tertiary air flow is used to transport light fraction fuel, then combustion efficiency is improved, but fuel classification complexity increases
Solution Approach 1:
Pneumatic classification using tertiary air flow is employed to separate light and heavy fuel fractions. The air stream naturally carries lighter particles forward while heavier particles fall behind, achieving classification without mechanical complexity. This pneumatic approach maintains combustion efficiency while minimizing 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 approach allows for efficient thermal energy provision to the calciner, enabling effective calcination of raw meal with reduced cooling requirements and enhanced internal energy use, while handling fuels of different sizes and weights effectively.
Implementation Method 1
Pieces of fuel having a low weight/surface ratio are 'dispersed' or 'suspended' in the tertiary air stream and thus transported by the tertiary air stream to the calciner
Implementation Method 2
transported by the tertiary air stream to the calciner, where they are combusted
Implementation Method 3
where they are combusted. Accordingly, the combustion heat is transferred directly to the raw meal in the calciner
Implementation Method 4
the combustion heat is transferred directly to the raw meal in the calciner
Implementation Method 5
pieces of fuel having a bigger weight/surface ratio than the pieces of the low weight fraction cannot be suspended in the tertiary air stream and literally drop through the tertiary air stream
Data Source
Figure 1
Figure 2
AI summary
Low grade fuel can be provided to a calciner 14 of a cement clinker line by providing at least a part of a tertiary air stream 130 from a clinker cooler 11 to the calciner 14 via a classification zone 24 of a classifier. A low weight fraction of the fuel 210 is transported by the tertiary air stream 130 from the classification zone 24 into the calciner 14. A high weight fraction passes the tertiary air stream 130 and is collected in the classification zone 24. Pieces of the low weight fraction are combusted in the calciner and the respective heat can be used for calcining raw meal 150, Pieces of the of the high weight fraction are subjected to dust blasting and combustion until the remaining parts thereof are transported into the calciner 14 by the tertiary air stream 130.