Fly Ash Carbon Burnout Using Self-Cooling Thermal Mixing
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Solution Overview
Problem
Fly ash generated from coal combustion is considered a waste product due to its environmental concerns and high treatment and disposal costs, and its moisture and carbon content make it unusable for building materials, while contact water from ash impoundments contaminates nearby water sources.
Innovation Solution
A method involving thermal treatment of fly ash to reduce carbon and moisture content, using an aqueous solution to control temperatures and mix with untreated ash to produce a low-carbon, low-moisture fly ash product suitable for concrete, with a system that includes a combustion chamber and mixing chamber without cooling jackets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If fly ash is thermally treated to reduce carbon content, then the fly ash becomes suitable for concrete use, but the treatment process increases operating costs and requires additional energy input
Solution Approach 1:
The system uses the fly ash itself as the cooling medium by contacting thermally treated fly ash with untreated fly ash, allowing the hot treated ash to cool itself through heat transfer to the cooler untreated ash, thereby reducing external cooling energy requirements
Solution Approach 2:
The process changes the temperature parameter of the fly ash through thermal treatment to achieve the desired carbon content reduction, then uses mixing with cooler ash to adjust the temperature back to acceptable levels for handling and storage
2Ease of manufacture
If wet fly ash is disposed of in landfills or ponds, then it is easily stored, but contact water contaminates groundwater and surface water sources
Solution Approach 1:
The system converts the harmful wet fly ash into a useful product by thermally treating it to burn off carbon and then mixing it with cool ash to create a low-carbon, low-moisture product suitable for concrete, thereby eliminating the need for harmful disposal methods
Solution Approach 2:
The process changes the moisture and carbon parameters of the fly ash through thermal treatment and mixing, transforming it from an unusable wet material into a suitable concrete additive
3Temperature
If cooling jackets are used in the combustion chamber, then temperature control is precise, but capital costs and device complexity increase
Solution Approach 1:
The system uses the fly ash material itself as the cooling medium, eliminating the need for external cooling jackets or external cooling systems, thereby reducing device complexity and capital costs while maintaining temperature control through the natural heat transfer between hot and cool ash streams
Solution Approach 2:
The untreated cool fly ash acts as an intermediary cooling medium that absorbs heat from the thermally treated hot fly ash, enabling temperature control without requiring complex external cooling systems
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
Reduces capital and operating costs, minimizes contact water treatment, and produces a fly ash product suitable for concrete, while reducing environmental contamination.
Implementation Method 1
The first portion of the recovered fly ash material is thermally treated in a combustion chamber
Implementation Method 2
The aqueous solution may include a liquid portion that at least partially vaporizes in the combustion chamber
Implementation Method 3
contacting the thermally treated fly ash with a second portion of the recovered fly ash material to cool the thermally treated fly ash
Data Source
AI summary
Systems and methods for beneficiating a recovered fly ash material and/or recovering fly ash from an impound site are described. The method may include thermally treating a first portion of a recovered fly ash material to form a thermally treated fly ash having a first temperature of at least 1000° F., and contacting the thermally treated fly ash with a second portion of the recovered fly ash material to cool the thermally treated fly ash to a second temperature of less than or equal to 500° F. and form a fly ash product. The fly ash product may have a carbon content less than 8% by weight, based on the total dry weight of the fly ash product.