Modified Fly Ash Production via Selective Carbon Removal
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Solution Overview
Problem
Existing technologies face challenges in producing fly ash with reduced unburned carbon content for use as cement or concrete mixing materials, as they either fail to ensure homogeneity in quality or require excessive energy for carbon removal.
Innovation Solution
A process involving classification of raw fly ash into crude and fine powders, heating the crude powder at 500-1000°C to remove unburned carbon, and adjusting the mixing ratio to achieve a modified fly ash with unburned carbon within a predetermined range, thereby reducing energy consumption and ensuring quality consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the entire raw fly ash is heated to remove unburned carbon, then the unburned carbon content is reduced, but the energy consumption increases significantly
Solution Approach 1:
The raw fly ash is divided into two size fractions using classification: fine powder (passing through the classifier) and crude powder (retained by the classifier). This segmentation allows selective processing where only the crude powder portion containing unburned carbon is subjected to heating treatment, while the fine powder is directly mixed into the final product. This resolves the contradiction by reducing the volume of material requiring energy-intensive heating while still achieving the desired reduction in overall unburned carbon content.
2Adaptability or versatility
If fly ash is used as mixing material for cement or concrete, then the utilization of coal ash is expanded, but the unburned carbon content must be kept low to meet quality standards
Solution Approach 1:
The unburned carbon is selectively removed from the crude powder fraction through heating treatment in the heating device. The fine powder fraction, which already has low unburned carbon content, is extracted and directly incorporated into the final modified fly ash without heating. This extraction approach efficiently reduces the overall unburned carbon content to meet quality standards for cement and concrete mixing materials while minimizing energy consumption.
3Productivity
If the power plant operates to generate electricity, then electric power is produced, but the quality of fly ash as a by-product fluctuates and may not meet mixing material standards
Solution Approach 1:
The system dynamically adjusts processing parameters based on the characteristics of incoming raw fly ash. The classification device separates particles by size, and the heating device processes only the crude powder fraction. By changing the processing parameters (classification cutoff size, heating temperature, heating time) based on the actual unburned carbon content and particle size distribution of the raw fly ash, the system maintains consistent quality of the modified fly ash output regardless of variations in the raw material from different power plant operating conditions.
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 process efficiently produces high-quality fly ash with reduced unburned carbon content, suitable for cement and concrete applications, while minimizing energy usage and maintaining quality stability.
Implementation Method 1
removing the unburned carbon contained in the crude powder by heating the crude powder at a temperature in a range of 500 to 1000°C
Data Source
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AI summary
A process for producing a modified fly ash comprising the steps of providing, as a raw material, the raw fly ash discharged from a pulverized coal combustion boiler; classifying the raw fly ash into a crude powder and a fine powder; removing the unburned carbon contained in the crude powder by heating the crude powder at a temperature in a range of 500 to 1000°C; and mixing together the crude powder from which the unburned carbon has been removed and the fine powder to obtain a modified fly ash.