Flash Column for CO2 Recovery Contaminant Removal
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Solution Overview
Problem
Conventional methods for recovering high purity carbon dioxide from gaseous sources, such as flue gases, face challenges with contaminants like nitrogen oxides, sulphurous compounds, and volatile organic compounds, which require costly and hazardous oxidation steps and result in inefficient energy consumption and product yield.
Innovation Solution
Incorporating a flash column between the absorption and stripper columns to remove contaminants, allowing for the reduction of oxygen and nitrogen oxides, thereby eliminating the need for oxidation steps and enhancing the overall efficiency of the carbon dioxide recovery process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional absorption method using amine-based agent is used to recover carbon dioxide, then carbon dioxide can be absorbed from gaseous source, but contaminants such as nitrogen oxides, sulphurous compounds and volatile organic compounds are also absorbed together with carbon dioxide
Solution Approach 1:
The absorption process is divided into two separate stages: first absorbing carbon dioxide with the amine-based agent, then selectively stripping contaminants in a separate step. This segmentation allows the system to achieve both carbon dioxide recovery and contaminant removal without compromising either function.
Solution Approach 2:
An intermediary stripping step is introduced between absorption and final separation. This intermediary process uses controlled heating to selectively release contaminants from the absorbing agent while retaining carbon dioxide, thereby mediating between the absorption of both substances and enabling their separate handling.
2Object-generated harmful factors
If oxidation step is used to remove contaminants from stripper off gas, then contaminant levels can be reduced, but hazardous chemicals are required and energy consumption increases
Solution Approach 1:
The patent converts the harmful effect of contaminants being absorbed into a benefit by utilizing the selective stripping process. The same absorbing agent that inadvertently absorbs contaminants is used to selectively release them through controlled heating, transforming the contamination problem into a separable feature.
Solution Approach 2:
Temperature is used as a controlling parameter to change the absorption characteristics of the amine-based agent. By adjusting temperature during the stripping step, contaminants are selectively released while carbon dioxide remains absorbed, enabling separation without oxidation or hazardous chemicals.
3Quantity of substance
If oxygen is present in the gaseous source and alkanolamine is used as absorbing agent, then carbon dioxide absorption proceeds, but oxygen causes degradation of alkanolamine and corrosion problems
Solution Approach 1:
A preliminary stripping step is performed before the main carbon dioxide release step. This preliminary action removes oxygen and other contaminants from the absorbing agent solution, preventing their harmful effects during subsequent processing while maintaining the agent's stability and effectiveness.
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 significantly reduces contaminant levels in the stripper off-gas, eliminates the need for hazardous chemicals, decreases energy consumption, and increases product yield by minimizing the loss of carbon dioxide during condensation.
Implementation Method 1
a gas comprising carbon dioxide, oxygen, N2, nitrogen oxides and optionally sulphurous compounds and volatile organic contaminants is fed into an absorption column and absorbed in a chemical absorbing agent, by which the gas is separated into a carbon dioxide-lean gas and a carbon dioxide-rich liquid
Implementation Method 2
The liquid is separated by means of flashing in a flash column into a N2-, NOx- and oxygen-rich gas and a N2-, NOx- and oxygen-depleted liquid
Implementation Method 3
The liquid is separated into a carbon dioxide-rich stripper off gas and a carbon dioxide-depleted liquid by means of stripping in a stripper column
Implementation Method 4
The gas is cooled in a condenser with a temperature as low as the dew point temperature of the gas
Data Source
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AI summary
The present invention describes a method for recovery of high purity carbon dioxide, which is substantially free of nitrogen oxides. This high purity carbon dioxide is obtained by introducing into the method a step in which carbon dioxide absorbed in an absorbing agent is flashed. The present invention also discloses a plant for recovery of said high purity carbon dioxide comprising an absorption column, a flash column, a stripper column, and a down stream purification unit comprising a washing column, a dehydrator, a condenser and a distillation unit.