CO2 Separation Process Using Scrubber Column to Prevent NOx Freezing
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Solution Overview
Problem
Existing CO2 capture processes struggle with the reliable and cost-effective removal of NOx impurities, particularly in cold temperatures, which can lead to freezing and non-compliance with product specifications.
Innovation Solution
A process involving cooling the feed stream to sub-zero temperatures, followed by partial condensation and distillation, expansion, vaporization, and compression, culminating in the use of a scrubber column to separate CO2 from NOx, without the need for a catalytic reactor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the feed stream is cooled to sub-zero temperatures for CO2 separation, then CO2 separation efficiency is improved, but NOx impurities freeze and contaminate the final product
Solution Approach 1:
The process segments the CO2 separation into two distinct operational phases: a cooling phase where the feed stream is cooled to sub-zero temperatures for efficient CO2 separation, and a heating phase where the separated CO2 stream is heated to above 0°C to prevent NOx freezing. This temporal and functional segmentation allows both high separation efficiency and product purity to be achieved simultaneously.
Solution Approach 2:
The CO2 separation is performed preliminarily during the cooling phase before the heating phase. By separating CO2 from the feed stream at low temperatures first, then heating the separated CO2 to prevent NOx freezing, the process ensures that NOx impurities do not contaminate the final product while maintaining high separation efficiency.
2Reliability
If conventional NOx removal methods (compression, drying, washing columns) are used, then NOx removal efficiency is improved, but energy consumption increases
Solution Approach 1:
The invention extracts and removes the need for conventional energy-intensive NOx removal equipment (compression stages, drying columns, washing columns) by utilizing the inherent temperature swing in the existing CO2 separation process. The NOx impurities are managed passively through temperature control rather than active removal mechanisms, dramatically reducing energy consumption while maintaining reliable NOx removal efficiency.
Solution Approach 2:
The process uses its own temperature variations to manage NOx impurities. The cooling phase naturally condenses and separates NOx, and the subsequent heating phase prevents NOx freezing in the final product. This self-service approach eliminates the need for external energy-intensive NOx removal systems.
3Temperature
If the CO2 stream is expanded to low pressure for vaporization, then cooling effect is improved, but NOx concentrate and reach solidification point
Solution Approach 1:
The CO2 separation from the feed stream is performed preliminarily during the cooling phase before expansion. By removing most CO2 from the feed stream first, the subsequent expansion of this separated CO2 stream does not concentrate NOx impurities to dangerous levels, preventing solidification while maintaining the desired cooling effect.
Solution Approach 2:
The process segments the CO2 handling into: (1) separation from feed stream at low temperature, (2) heating to prevent freezing, and (3) controlled expansion. This segmentation ensures that expansion occurs on a purified CO2 stream rather than a mixture, preventing NOx solidification while preserving the cooling effect needed for the separation process.
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 robust and energy-efficient method for separating CO2 from NOx, ensuring that NOx does not freeze and reducing energy consumption by optimizing the flow rates and recycling of streams.
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
separation of the cooled feed stream by partial condensation and/or distillation
Implementation Method 4
Expanding at least part of the first liquid, said expansion producing a second liquid
Implementation Method 5
At least partial vaporization of the second liquid in the heat exchanger or an auxiliary heat exchanger producing a second gas
Implementation Method 6
Compression of the second gas up to above 8 bara, preferably above 15 bara forming a compressed second gas
Implementation Method 7
Sending the compressed cooled second gas to the bottom of a scrubber column, and removing a bottom liquid of the scrubber column enriched in the at least one heavier component and containing carbon dioxide
Data Source
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AI summary
A process for separating CO2 from a feed stream (1) 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 (16) of the first liquid, producing a second liquid (23), vaporizing the second liquid in the heat exchanger (E1) producing a second gas (25), sending the compressed cooled second gas to the bottom of a scrubber column (K2) and removing a top gas (31) of the scrubber column depleted in the at least one heavier component.