Although the capture chemistry is fundamental, the performance of the overall system also depends on reliable mechanical separation.

Incomplete gas-liquid separation can result in:

• Solvent losses
• Liquid carryover
• Unstable level control
• Increased maintenance
• Reduced CO₂ product quality
• Damage to downstream compressors
• Fouling of downstream equipment
• Higher operating costs

Kapwell separation equipment can be designed to manage these risks and support stable carbon capture operation.

Multi-Stage CO₂ and Liquid Separation

A carbon capture regeneration system may require more than one gas-liquid separation stage.

Changes in temperature and pressure can cause water or solvent vapour to condense. Fine droplets may also remain suspended in the CO₂-rich gas after the bulk liquid has been removed.

Kapwell can develop staged separation arrangements based on the process conditions, liquid loading, gas flow, pressure-drop limitations and required outlet quality.

Primary CO₂ and Solvent Separation

The primary separator receives a mixed gas-and-liquid stream from the regeneration or desorption process.

Its purpose is to separate the bulk CO₂-rich gas from the regenerated liquid solvent.

The separator can provide:

• Gas-liquid disengagement space
• Liquid holding capacity
• Stable level-control volume
• Protection against liquid slugs
• Reduced solvent carryover
• Reduced gas carry-under
• Space for suitable inlet and separation internals

An inlet device may be used to reduce feed momentum, distribute the incoming flow and improve the initial separation of gas and liquid.

Effective primary separation helps recover valuable solvent and protects downstream CO₂-handling equipment.

CO₂ and Condensed-Water Separation

As a CO₂-rich gas stream cools, water vapour and other condensable components may form droplets or bulk liquid.

A secondary separator can be used to remove this condensed liquid before the CO₂ enters downstream conditioning or compression equipment.

The equipment can be designed to:

• Separate bulk condensate
• Maintain stable liquid levels
• Prevent excessive liquid carryover
• Reduce gas loss through the liquid outlet
• Accommodate operating variations
• Limit pressure drop

Low pressure drop is particularly important in carbon capture systems because unnecessary resistance can increase the energy required for vacuum generation, gas circulation or CO₂ compression.

Final Gas Polishing

A final gas-liquid separator may be used to remove smaller entrained droplets remaining after primary separation and cooling.

This polishing stage can improve the consistency of the CO₂-rich gas stream and help protect downstream compressors, heat exchangers, filters and conditioning equipment.

The final separator may include a mesh-pad demister, vane pack or another high-efficiency separation device selected for the required duty.

Collected droplets combine into larger liquid volumes and drain into the vessel, while the cleaner gas exits through the vapour outlet.

High-Efficiency Demisting Technology

Fine liquid droplets are more difficult to remove than bulk liquid.

Kapwell selects separation internals according to factors such as:

• Gas flowrate
• Gas density
• Liquid density
• Droplet size
• Liquid loading
• Operating pressure
• Operating temperature
• Turndown requirements
• Fouling potential
• Allowable pressure drop
• Required separation efficiency

Mesh-pad demisters are suitable for many carbon capture applications because they can provide:

• High droplet-removal efficiency
• Relatively low pressure drop
• Compact installation
• Passive operation
• Straightforward inspection
• Replaceable internal components
• Suitability for vertical or horizontal vessels

As droplets travel through the mesh structure, they collide with the wire surface, combine into larger droplets and drain back into the separator.

Kapwell can evaluate:

• Demister design velocity
• Available separation area
• Flooding margin
• Drainage capacity
• Liquid re-entrainment risk
• Wall bypass
• Internal support design
• Cleaning and removal requirements

This engineering approach helps ensure that the demister is correctly matched to the process rather than selected as a standard component without adequate verification.

Low-Pressure and Vacuum Separator Design

Some carbon capture regeneration systems operate at low pressure or under vacuum to encourage the release of CO₂ from the solvent.

These operating conditions introduce additional mechanical and process-design considerations.

Separator vessels, flanges, gaskets, nozzles and access covers must remain reliable under the required pressure and vacuum conditions.

Kapwell can assess:

• Internal design pressure
• External design pressure
• Full or partial vacuum conditions
• Operating and design temperatures
• Vessel stability under external pressure
• Flange and gasket suitability
• Start-up and shutdown conditions
• Condensation scenarios
• Blocked-outlet cases
• Relief and vacuum-protection requirements
• Nozzle loads
• Thermal expansion
• Safe venting and draining

Considering these conditions at an early stage can reduce the risk of air ingress, vessel instability, leakage and process interruptions.

Material Compatibility and Corrosion Control

Carbon capture solvents can create demanding operating environments.

Depending on the technology, separator equipment may be exposed to:

• Wet carbon dioxide
• Hot water
• Alkaline solvents
• Amine-based solvents
• Carbonate solutions
• Promoters and additives
• Solvent degradation products
• Cleaning chemicals
• Condensate
• Trace contaminants

Kapwell can review the compatibility of wetted equipment components, including:

• Vessel shells and heads
• Nozzles
• Separator internals
• Demister pads
• Inlet devices
• Gaskets
• Bolting
• Instrument connections
• Process piping

Material selection may include stainless steels, carbon steels with suitable allowances or coatings, and specialist alloys where required by the process.

Internal geometry can also be designed to minimise:

• Crevices
• Dead legs
• Stagnant pockets
• Solids accumulation
• Localised corrosion
• Areas where solvent could crystallise
• Locations that are difficult to inspect or clean

Where stainless steel is used, appropriate fabrication controls, cleaning, pickling and passivation may be specified to help maintain corrosion resistance and process cleanliness.

Clean-in-Place and Fouling Management

Fouling, scaling and solvent crystallisation can reduce separator performance over time.

Carbon capture equipment should therefore be designed with inspection, flushing and cleaning requirements in mind.

Kapwell can incorporate Clean-in-Place provisions such as:

• High-point vents
• Low-point drains
• Cleaning connections
• Utility connections
• Internal flushing points
• Spray nozzles where appropriate
• Removable demister pads
• Accessible manways and handholes
• Fully drainable vessel bottoms
• Minimum dead-leg geometry
• Chemical-compatible gaskets
• Removable separator internals

Designing for maintainability allows operators to inspect the equipment, clean internal surfaces and replace separation internals without cutting the vessel or carrying out unnecessary hot work.

A separator that performs well when new but cannot be cleaned or maintained effectively may not provide reliable long-term service.

Computational Fluid Dynamics for Separator Optimisation

Kapwell can use Computational Fluid Dynamics to support the development and verification of carbon capture separation equipment.

CFD allows engineers to visualise gas and liquid flow inside the separator and assess how the proposed vessel geometry and internal components influence performance.

CFD studies can help identify:

• Uneven inlet distribution
• High-velocity regions
• Recirculation zones
• Gas bypass
• Liquid accumulation
• Droplet trajectories
• Potential re-entrainment
• Pressure-drop locations
• Poor outlet distribution
• Areas susceptible to fouling

The results can support decisions relating to:

• Vessel diameter and length
• Inlet device selection
• Demister position
• Gas outlet location
• Liquid outlet arrangement
• Calming devices
• Anti-vortex devices
• Flow distribution internals

CFD does not replace sound process calculations and mechanical design. It provides an additional engineering tool that can help improve understanding of the internal flow behaviour and reduce design risk.

Modular and Skid-Mounted Carbon Capture Packages

Kapwell can integrate separators into modular process packages containing associated piping, valves, instrumentation and structural components.

A skid-mounted approach can offer several advantages:

• Reduced site-construction activity
• Controlled workshop fabrication
• Improved quality assurance
• Factory inspection and testing
• Simplified transportation
• Defined battery limits
• Reduced site interfaces
• Faster installation
• Easier replication
• Lower commissioning risk

Depending on the scope, a modular package may include:

• Gas-liquid separators
• Interconnecting piping
• Process valves
• Relief connections
• Instrument connections
• Level-control equipment
• Structural skid frames
• Access platforms
• Lifting arrangements
• Insulation
• Electrical and control interfaces

Kapwell considers equipment access, lifting, transportation, maintenance envelopes and package footprint during the design and integration process.

This approach can be particularly valuable for pilot plants, demonstration facilities, modular capture systems and repeatable commercial units.

Protecting Downstream CO₂ Equipment

Liquid carryover from a separator can negatively affect downstream carbon dioxide equipment.

Entrained water or solvent may cause:

• Compressor damage
• Corrosion
• Reduced heat-transfer performance
• Filter blockage
• Instrument problems
• Product contamination
• Unplanned shutdowns
• Increased maintenance requirements

Kapwell separator designs can be developed to reduce these risks by combining appropriate vessel sizing, liquid holdup, inlet conditioning and high-efficiency demisting.

The required separation performance should always be defined in relation to the downstream equipment and the complete operating envelope.

Supporting Reliable Solvent Recovery

Solvent can represent a significant operating cost within a carbon capture facility.

Reducing solvent carryover can therefore improve both environmental and commercial performance.

Effective gas-liquid separation helps:

• Recover solvent for recirculation
• Reduce solvent consumption
• Limit emissions and waste
• Maintain process chemistry
• Improve operating stability
• Reduce contamination of downstream equipment

Kapwell can design separator systems that balance solvent recovery, CO₂ gas quality, pressure drop, vessel size and maintainability.

Engineering and Quality Assurance

Carbon capture equipment must be suitable for its process duty and comply with the applicable regulatory and project requirements.

Kapwell’s engineering and supply scope can include:

• Process design calculations
• Separator sizing
• Internal selection
• Pressure-drop calculations
• Mechanical vessel design
• Material selection
• Nozzle and interface design
• General arrangement drawings
• Fabrication drawings
• Inspection and Test Plans
• Material traceability
• Welding documentation
• Non-destructive examination
• Pressure testing
• Dimensional inspection
• Factory Acceptance Testing
• Manufacturing data records
• Preservation and packing
• Installation and commissioning support

The exact scope can be tailored to the requirements of the technology developer, engineering contractor or plant operator.

Supporting the Carbon Capture Supply Chain

The continued development of carbon capture, utilisation and storage and direct air capture will require a capable engineering and manufacturing supply chain.

Kapwell combines experience in separation technology, pressure equipment, process systems and modular package integration.

By applying established industrial separation principles to emerging decarbonisation technologies, Kapwell can help bridge the gap between innovative carbon capture chemistry and dependable operating equipment.

From Captured CO₂ to a Reliable Product Stream

Capturing carbon dioxide into a solvent is only one part of the process.

The carbon dioxide must also be released, separated and delivered as a stable gas stream, while valuable solvent is recovered and returned to the capture system.

Reliable gas-liquid separation is therefore essential to the technical and commercial performance of a carbon capture facility.

Kapwell’s carbon capture separation capabilities include:

• CO₂ and solvent separation
• CO₂ and condensed-water separation
• Fine-droplet removal
• Gas polishing
• Mesh-pad demisting
• Vane-pack separation
• Pressure and vacuum vessel engineering
• Low-pressure-drop separator design
• Solvent-compatible material selection
• Clean-in-Place provisions
• CFD-supported optimisation
• Modular process-package integration
• Skid design and fabrication
• Inspection and testing
• Technical documentation

Through these capabilities, Kapwell can support cleaner CO₂ recovery, reduced solvent losses, improved equipment protection and reliable carbon capture operation.

Speak to Kapwell About Carbon Capture Separation Technology

Kapwell works with technology developers, engineering contractors and plant operators to develop separation equipment for carbon capture, solvent regeneration, direct air capture and CO₂ conditioning applications.

To discuss a carbon capture separator, desorber system or modular process package, contact Kapwell Ltd at info@kapwell.co.uk.