Core Technologies

CANS novel reactors

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'CANS' Novel Reactors

Johnson Matthey Process Technologies (JMPT) has developed a novel DAVYTM reactor design that provides increased efficiency whilst significantly reducing vessel sizes, equipment count and catalyst volumes.

This has been achieved through parallel developments in new catalyst formulations and reactor concepts.

Termed the DAVY ‘CAN’, the new reactor system consists of modular catalyst containers providing modified reactant flow paths. This configuration delivers improved mass transfer and kinetics plus low pressure drops, enabling reactor intensification.

Initially conceived for the DAVY / BP Fischer Tropsch (FT) technology, DAVY CANS retain the original tubular fixed-bed configuration, modularity, easy scale-up and non-proprietary manufacture of our FT reactors, but with significantly improved performance.

Today, the DAVY CAN principle is not limited to FT, and we continue to develop this technology for application in a number of heterogeneous reaction systems.

DAVY is a trade mark of the Johnson Matthey group of companies.

In Context

JMPT initially developed DAVY CANS to reduce the size of the fixed-bed reactors used in the DAVY / BP Fischer Tropsch flow sheet.

The goal was to better match the FT conversion reactors with the full range of DAVY reforming technologies, from < 1,000bbl/day to > 20,000bbl/day.

The objectives underpinning the DAVY CANS development were:

  • High productivity (with low catalyst volume)
  • Low by-product formation
  • Use of smaller catalyst particles to reduce mass transfer resistance
  • Use of larger diameter tubes (in small reactors of lower weight)
  • Higher heat transfer
  • Standard temperature gradients
  • Lower pressure drop
  • Use of non-proprietary reactor.

With these objectives in mind, JMPT developed new reactors and catalysts in parallel using the following guiding principles:

Principles for reactor improvement

  • Retain the basic tubular fixed-bed design
  • Continue non-proprietary reactor manufacture to maintain a variety of vendors and create supply competition to reduce cost.

Principles for catalyst improvement

  • Evolution of formulation
  • Achieve a “drop in” solution.
CANS Flowsheet

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CANS Reactor Description

The key challenges facing FT technology are: the highly exothermic FT reaction requiring improved heat removal; and the diffusion resistance imposed on the gaseous reactants by the paraffinic product inside the catalyst pores, which requires improved mass transfer.

DAVY CANS directly address these challenges by improving the conventional tubular fixed-bed reactor design, which is always a compromise between:

  • Tube diameter
  • Tube length
  • Superficial velocity
  • Heat transfer
  • Pressure drop
  • Catalyst pellet size
  • Catalyst pellet strength.

The DAVY CANS design

A number of CANS are loaded into a large diameter tube, effectively creating adiabatic reactors in series with intercooling.

Each CAN carries catalyst, manages reactant flow path and enables efficient heat removal.

The design allows radial flow through each CAN, so even in a long tube the sum total of the catalyst bed thickness is low –  around 15% of the tube length.

This means only a small pressure drop exists across each CAN, allowing the use of small catalyst particles with very low internal diffusion resistance which in turn gives a large improvement in performance.

The radial flow also ensures that the reactants are at their hottest at the tube wall, rather than the tube centre as with conventional designs.  This produces the highest ΔT at the point with the highest heat transfer coefficient, greatly increasing heat removal capacity.

Catalyst

The CANS FT catalyst development (carried out by our technology partners BP) focused on improved heat and mass transfer to better facilitate the Fischer Tropsch reaction, shown below:

CANS big equation


The new CANS catalyst formulation delivers:

  • Improved kinetics (better activity overall and improved selectivity response to temperature)
  • Improved structure
  • Improved strength.

CANS catalyst results:

  • Much lower catalyst volume
  • Significant improvement in productivity
    per tube
  • Better selectivity
  • Lower exotherm.

The larger pellets employed in existing conventional fixed-bed FT systems face challenges both in terms of heat and mass transfer.  The lower pressure drop offered by CANS allows it to operate using a smaller catalyst pellet, delivering the following improvements:

Mass transfer

  • A small pellet has a shorter pathway to the catalyst active surface, which minimises the partial pressure gradient of the reactants within the pellet
  • This delivers a higher reaction rate with lower by-products make
  • Active site blockage is also reduced, increasing their accessibility for reactants.

Heat transfer

For the highly exothermic FT reaction, heat
removal is vital for catalyst protection and maintaining selectivity.

The parameters crucial to achieving this heat removal are particle size and structure.

A smaller pellet has:

  • Shorter heat transfer route
  • Lower centre temperature
  • Better heat transfer to bulk gas.
The Davy Advantage

The DAVY CAN is the step-change that will transform Fischer Tropsch and other reaction systems into lighter-weight and more modular technologies.

The combined improvements CANS offer will deliver lower catalyst volumes with fewer equipment items, significantly reducing plant costs.  The catalyst is delivered pre-reduced and activated in the CAN, reducing the costs and risks associated with catalyst loading and reduction on-site.

Read more below:

+Improved performance and efficiency:

  • Three-fold increase in production for a given size reactor
  • Each layer of catalyst has a small pressure drop, enabling the use of much smaller particles which give a large performance improvement
  • CANS reactors improve FT catalyst performance in a tube by a factor of more than three and with intrinsically better selectivity
  • Reactor temperature profile is turned inside out so largest ΔT is at tube wall, allowing more efficient heat transfer and better control of reaction temperature and selectivity with lower tube heat transfer surface area per unit volume of catalyst
  • Employs a single-stage recycle loop which can operate with > 50% inerts
  • Spent catalyst returned in the CAN.

+Versatility:

  • Can be applied at all plant scales
  • The CAN principle does not only apply to FT and JMPT are busy developing new processes based on the technology for a number of reaction systems.

+Ease of fabrication:

  • CANS reactors are of the simple tubular design currently used in FT
  • Non-proprietary manufacture
  • The CANS are an enlarged version of a famous beverage container and can be easily and economically mass manufactured.

+On-site improvements:

  • Number of tubes reduced by 95% compared with conventional fixed-bed reactors
  • Catalyst weight reduced by > 70%
  • Reactor is modular and can be tailored to local transport constraints
  • Delivers reactor weight productivities similar to micro-channel reactors but with simpler fabrication
  • On-site catalyst reduction and regeneration equipment not required.

+Cost reductions:

  • FT section cost reduced by over 50% compared with conventional fixed-bed FT.
Related Processes & Core Technologies

CANS technology was initially developed to further improve DAVY / BP Fischer Tropsch technology, which is the key step in the DAVY / BP gas-to-liquids (GTL) process. Explore GTL here:

Find out more about DAVY / BP FT technology here:


Related Processes

CANS technology was initially developed to further improve DAVY / BP Fischer Tropsch technology, which is the key step in the DAVY / BP gas-to-liquids (GTL) process. Explore GTL here:


Core Technologies

Find out more about DAVY / BP FT technology here: