Rotating Drum Absorber for Compact CO2 Capture
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Solution Overview
Problem
Conventional carbon dioxide removal plants from flue gas are bulky, complex, and inefficient, with limitations on the viscosity of absorbents used, which restricts the range of chemicals and concentrations, and require extensive piping and instrumentation.
Innovation Solution
The compact atmospheric rotating absorber (CARA) uses a rotating drum with integrated absorption, droplet removal, and washing sections, employing centrifugal force to distribute viscous absorbent droplets in a cross-flow direction, combined with perforated cylinders for droplet disintegration and energy recovery systems to enhance CO2 absorption and reduce energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional absorption columns are used for CO2 removal, then CO2 absorption can be achieved, but the plant becomes bulky and requires extensive piping and instrumentation
Solution Approach 1:
The patent combines the absorption column, cooler, and other process units into a single integrated rotating drum structure. The drum contains multiple sections (absorption section, droplet removal section, washing section) that perform multiple functions simultaneously, eliminating the need for separate bulky units and extensive piping connections between them.
Solution Approach 2:
The patent employs a rotating drum design where the entire absorption apparatus rotates within the flue gas duct. This dynamic structure allows the absorption liquid to be distributed and recirculated through rotation, replacing static piping systems with a moving mechanical system that achieves the same mass transfer function more compactly.
2Productivity
If conventional absorption columns are used, then CO2 removal is achieved, but the plant size increases significantly
Solution Approach 1:
The patent nests multiple functional sections within the rotating drum structure. The absorption section, droplet removal section, and washing section are arranged concentrically or sequentially within the same rotating volume, allowing multiple process functions to occupy the same spatial envelope that would traditionally require separate buildings or large equipment footprints.
Solution Approach 2:
The patent transitions from a vertical stacked arrangement of process units to a horizontal rotating drum configuration within the duct. By utilizing the rotational dimension and the duct space, the system achieves high CO2 removal capacity without increasing the plant's ground footprint or requiring tall vertical structures.
3Adaptability or versatility
If highly viscous absorbents are used, then the range of chemicals and concentrations is expanded, but conventional systems cannot handle the viscosity
Solution Approach 1:
The rotating drum design creates dynamic motion that actively circulates and distributes viscous absorbents throughout the absorption section. The rotation generates centrifugal forces and internal mixing that prevent settling and maintain uniform distribution of high-viscosity liquids, which would be difficult to pump and distribute in conventional static systems.
Solution Approach 2:
The system uses the flow of flue gas itself as the driving force to circulate the absorption liquid through the rotating drum. The gas flow creates pressure differences and drag forces that move the liquid through the system without requiring additional pumps, making the system compatible with viscous absorbents that would be difficult to pump mechanically.
4Productivity
If conventional plants are used for CO2 removal, then absorption function is provided, but energy efficiency is reduced
Solution Approach 1:
The rotating drum system uses the kinetic energy of the flue gas flow itself to drive the circulation of absorption liquid and maintain the rotation of the drum. The gas flow provides the driving force for liquid distribution and recirculation without requiring external motors or pumps, making the system energy-self-sufficient and highly efficient.
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 the size and cost of CO2 removal units by over 90% and 50%, respectively, while allowing the use of highly viscous absorbents and improving CO2 absorption efficiency through increased turbulence and energy recovery, resulting in a compact, efficient, and cost-effective solution.
Implementation Method 1
the absorption process is carried out by forcing droplets of absorption liquid to move in a cross-flow direction to the flue gas flow by aid of centrifugal force
Implementation Method 2
The rotation of the droplet disintegration means increases the turbulence in the gas and increases the mass transfer of CO 2 from flue gas to the absorbent
Implementation Method 3
the speed difference between the droplets of absorption liquid and the gas stream, the relative speed, is high. This has the benefit that turbulence within the droplets increases, thus absorption is improved
Implementation Method 4
liquid is removed, drained, from the drum by the use of diffusers such that kinetic energy in the liquid is recovered and converted into hydrodynamic energy, a pressure head, which is used as hydraulic driving force of the drum
Data Source
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AI summary
The invention relates to an apparatus 1 for absorbing CO2 from a gas stream of flue gas 2 comprising a stationary casing 4 having a longitudinal axis A, a gas stream inlet 5 and a gas stream outlet 6, said casing comprising at least one drum 7 being rotatable about the longitudinal axis, said drum having at least one absorption section 8 arranged within the drum provided with spray means 18 for spraying absorption liquid into the stream of flue gas containing CO2 to form a cross-flow of droplets 19 of absorption liquid to the flow direction of the gas stream by the effect of centrifugal force, and having means for disintegration 20 of droplets, at least one droplet removal section 9 arranged after the absorption section 8 in the flow direction of the gas stream, at least one washing section 10 arranged after the droplet removal section 9 in the flow direction of the gas stream,said apparatus 1 having means for rotating the drum 13 such that the absorption section, the droplet removal section and the washing section rotate about the longitudinal axis, and said apparatus having means for energy recovery. The invention also relates to a process for absorbing CO2 from a gas stream of flue gas.