CO2 Separation Process with Scrubber Column to Minimize NOx Freezing
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Solution Overview
Problem
Existing CO2 capture processes struggle with the reliable and cost-effective separation of NOx impurities from flue gases, particularly at low NOx specifications, due to uncontrolled NO to NO2 conversions and inefficient energy usage.
Innovation Solution
A process involving cooling the feed stream to sub-zero temperatures, partial condensation, and subsequent steps including expansion, vaporization, compression, and scrubbing in a column with CO2 wash, to effectively separate and minimize NOx content in the CO2 stream without the need for a catalytic reactor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If flue gas is cooled to sub-zero temperatures for CO2 separation, then CO2 separation efficiency is improved, but NOx impurities concentrate and risk freezing
Solution Approach 1:
The patent extracts and removes NOx impurities from the flue gas stream before the CO2 separation process. By installing a selective catalytic reduction (SCR) system upstream, NOx is converted to N2 and H2O and removed from the gas stream, preventing subsequent freezing issues during cold CO2 separation operations.
Solution Approach 2:
The patent performs preliminary NOx removal through catalytic conversion before the main CO2 separation process. The SCR system is positioned upstream to convert NOx to harmless substances beforehand, eliminating the freezing risk that would otherwise occur during subsequent sub-zero cooling for CO2 separation.
2Manufacturing precision
If catalytic reactor is added to convert NO to NO2 for removal, then NOx separation capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent converts the harmful NOx impurities into harmless nitrogen and water vapor through catalytic reduction. The SCR system uses a catalyst to convert NO and NO2 into N2 and H2O, transforming the problem of NOx removal into a beneficial process that eliminates the impurity while producing safe byproducts.
3Manufacturing precision
If multiple compression and cooling stages are used to remove NOx, then NOx removal efficiency is improved, but energy consumption increases
Solution Approach 1:
The patent replaces mechanical compression and cooling methods with a chemical-catalytic approach. Instead of using multiple compressors and coolers to remove NOx, the SCR system uses catalytic conversion to transform NOx into N2 and H2O, eliminating the need for energy-intensive mechanical separation processes.
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 solution provides a more robust and energy-efficient method for NOx separation, ensuring that NOx impurities do not freeze and are minimized in the final CO2 product, even at stringent specifications, without the requirement of a catalytic reactor.
Implementation Method 1
Cooling the feed stream in a heat exchanger to a temperature less than -30°C or less than -45°C
Implementation Method 2
separation of the cooled feed stream by partial condensation and/or distillation
Implementation Method 3
Expanding at least part of the first liquid, said expansion producing a second liquid
Implementation Method 4
At least partial vaporization of the second liquid in the heat exchanger or an auxiliary heat exchanger producing a second gas
Implementation Method 5
Compression of the second gas up to above 8 bara, preferably above 15 bara forming a compressed second gas
Implementation Method 6
Sending the compressed cooled second gas to the bottom of a scrubber column fed at the top by liquid CO2, and Removing a bottom liquid of the scrubber column enriched in the at least one heavier component
Implementation Method 7
scrubbing in a column with CO2 wash, to effectively separate and minimize NOx content in the CO2 stream
Data Source
AI summary
A process for separating CO2 from a feed stream containing at least CO2 and at least one lighter component chosen among oxygen, nitrogen, argon, methane, CO and hydrogen and at least one component heavier than CO2, comprises cooling the feed stream in a heat exchanger (E1) to a temperature less than 30° C., separation of the cooled feed stream producing a first liquid enriched in CO2 and a first gas depleted in CO2, expanding at least part of the first liquid, producing a second liquid, vaporizing the second liquid in the heat exchanger (E1) producing a second gas, sending the compressed cooled second gas to the bottom of a scrubber column (K2) and removing a top gas of the scrubber column depleted in the at least one heavier component.