Ammonia Injection for Sulfur Trioxide Control in Coal Furnaces
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Solution Overview
Problem
The existing methods for controlling nitrogen oxide and sulfur trioxide emissions from coal-fired furnaces and boilers, such as selective catalytic reactors, result in visible acid mist formation known as 'blue plume,' which contaminates fly ash and increases ammonia costs, making it unusable for concrete production.
Innovation Solution
A system that introduces ammonia to react with sulfur trioxides in exhaust emissions, precipitates fly ash and ammoniated compounds, and recovers ammonia for reuse, preventing the formation of sticky ammonium bisulfate and ensuring the fly ash remains usable by converting it into ammonium sulfate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If ammonia is injected to react with sulfur trioxides to eliminate acid mist and blue plume, then the formation of acid mist is eliminated, but ammonium bisulfate builds up on downstream equipment causing operational problems
Solution Approach 1:
The patent changes the chemical parameters by injecting excess ammonia to shift the reaction equilibrium from forming ammonium bisulfate (NH4HSO4) to forming ammonium sulfate ((NH4)2SO4). This parameter change transforms the harmful sticky substance into a beneficial dry powder that can be easily removed with fly ash, resolving the contradiction between eliminating acid mist and preventing equipment buildup.
2Object-affected harmful factors
If large amounts of ammonia are injected to control blue plume, then acid mist formation is prevented, but the cost of ammonia increases substantially
Solution Approach 1:
The patent converts the harmful excess ammonia injection into a beneficial process by capturing the formed ammonium sulfate with fly ash. The fly ash acts as a carrier to remove the ammoniated compounds, transforming the costly ammonia consumption into an effective emission control mechanism where the byproduct is valorized rather than wasted.
3Object-affected harmful factors
If ammonia is used to control sulfur trioxide emissions, then acid mist is eliminated, but fly ash quality deteriorates making it unusable for concrete production
Solution Approach 1:
The patent merges the ammonia injection process with the existing fly ash collection system. Instead of treating ammonia injection as a separate process that contaminates fly ash, the patent integrates it so that fly ash serves dual purposes: capturing ammoniated compounds from the gas stream and maintaining its value as a concrete additive. The combined process eliminates acid mist while preserving fly ash usability.
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 system effectively reduces nitrogen oxides and sulfur trioxides emissions while recovering ammonia, preventing downstream equipment damage and maintaining the quality of fly ash for concrete applications, thus reducing costs and environmental impact.
Implementation Method 1
ammonia reacts readily with the sulfur trioxide to form a number of possible compounds, the most notable of which are ammonium sulfate and ammonium bisulfate
Implementation Method 2
at least a portion of fly ash particles and the ammoniated compounds in the exhaust emission are precipitated
Implementation Method 3
at least a portion of the ammonia from the precipitated ammoniated compounds is recovered with heat from the exhaust emission
Data Source
AI summary
A method and system for controlling one or more emissions includes introducing ammonia to react with at least a portion of sulfur trioxides in an exhaust emission and result in at least one or more ammoniated compounds. At least a portion of fly ash particles and the ammoniated compounds in the exhaust emission are precipitated. At least a portion of the ammonia from the precipitated ammoniated compounds is recovered with heat from the exhaust emission and the recovered ammonia is reused.