Flue Gas Impurity Removal via Indirect Cooling and Scrubbing
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Solution Overview
Problem
Current flue gas desulphurization techniques are unable to reduce impurity concentrations, such as SO3, SO2, and NO2, to below 10 ppmv, leading to carbon capture solvent degradation, increased emissions, and higher costs due to accelerated solvent loss and emissions, and the need for continuous supplementation.
Innovation Solution
A method and system involving indirect cooling of flue gases using heat exchangers and a scrubbing solution comprising sodium bicarbonate or sodium carbonate to reduce impurity concentrations before carbon capture, preventing acid mist formation and extending solvent lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional flue gas desulphurisation techniques are used, then the process is simple and cost-effective, but the impurity concentration cannot be reduced to below 10 ppmv
Solution Approach 1:
The impurity removal process is divided into multiple stages: first cooling the flue gas to condense SO3 and remove acid mist, then using a scrubbing solution to remove SO2 and NO2. This segmentation allows each stage to target specific impurities effectively, achieving concentrations below 10 ppmv that cannot be achieved by single-stage traditional methods.
Solution Approach 2:
The flue gas is cooled and pre-treated to remove acid mist and condense SO3 before the main scrubbing process. This preliminary action protects the carbon capture solvent from degradation by acid mist, enabling the subsequent scrubbing process to achieve higher impurity removal efficiencies without solvent damage.
2Reliability
If impurity concentration is not reduced prior to carbon capture, then the carbon capture process is simpler, but solvent degradation and loss accelerate
Solution Approach 1:
The flue gas is cooled to condense and remove acid mist (SO3) before contact with the carbon capture solvent. This preliminary anti-action prevents acid mist from degrading the solvent, extending solvent lifespan and reducing losses. The scrubbing solution simultaneously removes SO2 and NO2, providing comprehensive protection against solvent degradation.
3Loss of substance
If acid mist is present in the flue gas, then the cooling process is simpler, but solvent emissions increase
Solution Approach 1:
The flue gas temperature is controlled to be above the dew point of SO3 during the cooling process, preventing condensation and acid mist formation. By maintaining this temperature parameter, the system avoids solvent emissions caused by acid mist while still achieving effective impurity removal through the scrubbing solution.
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 method effectively reduces impurity concentrations to below 2 ppmv, minimizing solvent degradation, emissions, and operational costs, while enhancing carbon capture efficiency and reducing the load on Effluent Treatment Plants.
Implementation Method 1
indirectly cooling a flue gas comprising carbon dioxide (CO2), the flue gas having a starting temperature of from 115° C. to 200° C., to form a cooled flue gas having a cooled temperature of less than 95° C.
Implementation Method 2
contacting the further cooled flue gas with a carbon capture solvent such that the carbon capture solvent removes carbon dioxide (CO2) from the cooled flue gas
Implementation Method 3
Acid mist is formed in a boiler or a wet flue gas desulphurisation vessel when the temperature of a flue gas drops below the dew point of SO3. At these temperatures, SO3 condenses either as small fog droplets resulting in the formation of acid mist
Data Source
AI summary
The present invention relates to a method and a system for the removal of impurities from a flue gas. In particular, the present invention relates to a method and a system for the removal of impurities such as SO3 (acid mist), SO2 (sulphur dioxide), NO2 (nitrogen dioxide) from a CO2 (carbon dioxide) rich flue gas.