Coal-Fired Furnace Slag Reduction via Dual Chemical Additives
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Solution Overview
Problem
Coal-fired furnaces experience excessive slag formation due to molten ash deposition, leading to operational issues such as clogged gas flow, thermal imbalances, and reduced heat transfer efficiency, especially when using coal with ash characteristics different from the design fuel, where existing methods like soot blowing and load reduction are inadequate or economically undesirable.
Innovation Solution
Combusting coal in the presence of specific slag-reducing ingredients like magnesium carbonate and copper acetate, which are added in amounts up to 2000 ppm, to synergistically reduce slag formation by a factor of 10 to 100 compared to using either ingredient alone, acting as both slag reducers and combustion catalysts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If coal with different ash characteristics is used to meet demand or emission regulations, then fuel flexibility and emission compliance are improved, but slag formation increases significantly
Solution Approach 1:
The patent introduces slag-reducing ingredients (magnesium carbonate, magnesium hydroxide, magnesium oxide, magnesium sulfate, copper acetate, copper nitrate, aluminum nitrate, aluminum oxide, aluminum hydroxide, ammonium phosphate) as intermediary substances that modify the ash melting behavior. These ingredients act as mediators between the coal combustion process and the slag formation problem, changing the chemical composition and physical properties of the ash to prevent excessive slagging while allowing flexibility in coal selection.
Solution Approach 2:
The patent changes the chemical parameters of the combustion system by adding specific slag-reducing ingredients in controlled amounts (up to 2000 ppm). This modifies the ash fusion temperature, viscosity, and other critical parameters that control slag formation, enabling the use of different coal types without excessive slagging problems.
2Object-generated harmful factors
If soot blowing is used to remove slag deposits, then slag accumulation is reduced, but operational interruptions and energy consumption increase
Solution Approach 1:
The patent applies slag-reducing ingredients during the combustion process itself, performing preliminary action to prevent slag accumulation before it becomes problematic. By modifying the ash properties in advance through chemical additives, the need for subsequent mechanical removal operations like soot blowing is reduced, thereby minimizing operational interruptions.
3Object-generated harmful factors
If boiler load is reduced to minimize slag formation, then slagging is decreased, but productivity and energy output are reduced
Solution Approach 1:
The patent changes the chemical composition parameters of the combustion system by adding slag-reducing ingredients, which allows the boiler to maintain high load operation without excessive slag formation. The additives modify the ash melting characteristics, enabling full productivity operation while controlling slagging through chemical means rather than operational reduction.
4Object-generated harmful factors
If slag-reducing ingredients are added to control slag formation, then slagging is reduced, but operational complexity and monitoring requirements increase
Solution Approach 1:
The patent combines multiple functions into the slag-reducing ingredients themselves, which simultaneously act as slag modifiers and combustion catalysts. This merging of functions reduces the need for separate monitoring and control systems, as the additives provide dual benefits while simplifying the overall operational 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 process significantly reduces slag formation, maintaining operational efficiency and preventing thermal imbalances, while being economically viable by minimizing the need for frequent load reduction and attemperating spray usage.
Implementation Method 1
combusting the coal in the presence of a first slag-reducing ingredient and a second slag-reducing ingredient in amounts effective to reduce slag formation in the furnace
Implementation Method 2
acting as both slag reducers and combustion catalysts
Data Source
AI summary
There is provided a process for operating a coal-fired furnace to generate heat. The process has the steps of a) providing the coal to the furnace and b) combusting the coal in the presence of a first slag-reducing ingredient and a second slag-reducing ingredient in amounts effective to reduce slag formation in the furnace. The first slag-reducing ingredient and the second slag-reducing ingredient are different substances. The first slag-reducing ingredient is selected from the group consisting of magnesium carbonate, magnesium hydroxide, magnesium oxide, magnesium sulfate, and combinations thereof. The second slag-reducing ingredient is selected from the group consisting of copper acetate, copper nitrate, aluminum nitrate, aluminum oxide, aluminum hydroxide, and ammonium phosphate. There is also provided a method for reducing slag formation in a coal-fired furnace.