Dry Alkaline Injection System for Acid Gas Mitigation
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Solution Overview
Problem
Existing systems for controlling acid gas emissions in coal- and biomass-fired sources face issues with scaling and clogging due to the reaction of hydrated lime with carbon dioxide, leading to reduced reactivity and increased maintenance needs.
Innovation Solution
A system that compresses a carrier gas to remove moisture and CO2, maintaining a low dew point and temperature to minimize carbonate formation, combined with a lance cooling system to further reduce scaling, and an eductor nozzle for uniform additive distribution, while also incorporating a CO2 removal device to preserve the reactivity of hydrated lime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If dry alkaline materials are injected into flue gas stream to control acid gases, then acid gas emissions are controlled, but carbonate formation occurs leading to scaling and clogging
Solution Approach 1:
The system pre-cools the carrier gas before it contacts the hydrated lime, and maintains cooling of the injection system components throughout operation. This preliminary and continuous cooling action prevents the temperature conditions that would otherwise cause rapid carbonate formation, thereby preventing scaling and clogging before they can occur
Solution Approach 2:
The invention changes the temperature parameter of the carrier gas and injection system from ambient or elevated temperatures to controlled low temperatures (maintaining carrier gas below 95°F and injection system below 70°F). This parameter change fundamentally alters the reaction kinetics to minimize carbonate formation while preserving hydrated lime reactivity
2Object-affected harmful factors
If the injection system temperature is reduced to minimize carbonate formation, then scaling is reduced, but the reactivity of hydrated lime may be affected
Solution Approach 1:
The system applies different temperature conditions to different zones: the carrier gas is cooled to below 95°F and the injection system components are maintained below 70°F to prevent carbonate formation, while the actual injection into the hot flue gas stream (above 95°F) provides the necessary heat for the acid gas neutralization reaction to occur effectively
Solution Approach 2:
The hydrated lime is pre-cooled with the carrier gas before injection to prevent premature carbonate formation in the storage and conveying system, but upon contact with the hot flue gas, the lime rapidly reacts with acid gases. This preliminary cooling preserves reactivity by preventing deactivation through carbonate formation, while the hot flue gas provides necessary reaction conditions
3Quantity of substance
If conventional dehumidification and cooling systems are used, then moisture levels are reduced, but scaling and clogging still occur due to limited cooling capacity
Solution Approach 1:
The system implements aggressive temperature parameter changes, cooling the carrier gas to below 95°F and injection system components to below 70°F, which is more stringent than conventional systems. This extended cooling parameter range fundamentally prevents carbonate formation kinetics while also achieving moisture removal, thereby eliminating scaling and clogging
Solution Approach 2:
The carrier gas is cooled and dehumidified before it contacts the hydrated lime, and the injection system components are pre-cooled and maintained at low temperatures throughout operation. This preliminary and continuous cooling action prevents carbonate formation before it can occur, rather than attempting to address scaling after it has formed
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 effectively reduces carbonate formation, maintains the reactivity of hydrated lime, and minimizes maintenance needs by preventing scaling and clogging, thereby enhancing the reliability and efficiency of acid gas mitigation.
Implementation Method 1
compressing, by a compressor, a carrier gas to form a compressed carrier gas
Implementation Method 2
contacting an additive with the compressed carrier gas to form an additive-containing fluid
Implementation Method 3
a refrigerated air dryer 212 and/or after cooler 216
Implementation Method 4
The lance(s) is cooled by a cooling medium to maintain an interior of the at least one lance at a temperature below the temperature of the contaminated gas stream
Implementation Method 5
The lance(s) comprises an eductor nozzle
Implementation Method 6
The lance(s) is cooled by a cooling medium to maintain an interior of the at least one lance at a temperature below the temperature of the contaminated gas stream
Data Source
AI summary
The present disclosure is directed to the introduction of an additive to a contaminated gas stream. An additive introduction system uses a compressor and carbon dioxide separator to provide a treated carrier gas for introduction of an alkaline additive to a contaminated gas stream.