Core Technologies

Methanation

Select each section header below to expand, or click here to expand/collapse all sections
Methanation

Methanation refers to the production of methane by the equilibrium reaction of carbon monoxide and hydrogen:

This highly exothermic reaction is the reverse process of steam methane reforming.

In Context

Davy methanation technology forms the core of our substitute natural gas (SNG) process, which converts gasified coal into high methane-content fuel gas.

Our methanation technology, utilising CRGTM catalysts from Johnson Matthey, performs the key chemical transformation of syngas into SNG, and ensures the final product is of a suitable quality for injection into gas distribution networks.

The CRG catalyst facilitates the methanation reaction and also a simultaneous CO shift reaction.

The CO shift reaction consumes excess CO2 and increases the CO content of the gas, which is necessary for methanation:

CO shift:

methanation_small_equation1

Methanation:

methanation_small_equation2

Methanation Flowsheet

Roll over the numbers on the flowsheet to see more information

Tap diagram to view larger
Process Description

The Davy methanation system comprises a series of reaction vessels charged with CRG catalysts from Johnson Matthey.

The process is split between two stages: bulk and trim methanation. Bulk methanation proceeds at high temperature and facilitates most of the feed conversion, while the low-temperature trim stage reacts residual feed to maximise the final methane content of the product stream.

The bulk methanation duty is typically shared between two vessels, with a recycle stream running from the output of the second reactor back to the first reactor.

Using two reactors with split feed distribution reduces the required catalyst volume and reactor diameters. In addition, the recycle stream helps to control the system temperature, given the highly exothermic nature of the methanation reactions. Recycling also maximises conversion – however, using two reactors minimises the recycle rate required to achieve this.

Purified syngas feed is split between the two bulk reactors.  The stream directed to the first bulk reactor mixes with the recycle gas and then enters the reaction vessel.  Inside, the gases flow over the adiabatic CRG catalyst bed, where the exothermic shift and methanation reactions proceed to equilibrium.

The process stream leaving the first bulk reactor mixes with the remainder of the fresh feed that bypassed the first methanation step and enters the second bulk reactor, where again the CRG-catalysed shift and methanation reactions proceed to equilibrium.

The product from the bulk methanation stage then splits between the recycle steam and the trim methanation stage.  Trim methanation also takes place across two CRG catalyst reactors, which maximises the conversion and also helps to reduce the required recycle rate at the bulk methanation stage.

After leaving the final trim methanation reactor, the methanated gas is cooled to remove water, further enriching the product gas for export.

Generally, two bulk and two trim methanation stages provide the optimum flow sheet for Davy SNG plants.

However, our methanation technology can be designed with alternative configurations to cater to different plant requirements.

Some of these alternative configurations and their applications are shown below:

 

Catalyst

Part of Johnson Matthey’s KATALCO® range, CRG catalysts have been developed in conjunction with JM Davy’s methanation technology. Advantages of the CRG catalysts are outlined below.

KATALCO® is a registered trade mark of Johnson Matthey Plc.


A unique formulation

  • Enables CRG to catalyse the methanation and shift reactions simultaneously.

Excellent stability at high temperatures

  • Makes CRG ideal for the bulk methanation step.

High activity at low temperatures

  • Makes CRG the obvious choice for the trim methanation step.

Availability in a range of shapes and sizes

  • Provides the optimum combination of low pressure drop and high active area.

Structural strength

  • Enables CRG to withstand transient start-up and upset conditions without damage.

Excellent poison retention

  • Underpins long catalyst life and durability.

Being supplied pre-reduced and stabilised

  • Avoids expensive start-up equipment
    and enables a rapid plant start-up.
The JM Davy Advantage

The combination of JM Davy design and CRG catalysts from Johnson Matthey underpins our methanation technology, which delivers the following advantages:

+Long-term proven process

  • CRG catalyst from Johnson Matthey has been used in SNG plant operation for over 30 years.
  • JM Davy has many years’ experience in high temperature equipment design and specification.

+Efficient design:

  • Heat recovery maximised.
  • Compressor power minimised.
  • Methanation stages minimised.
  • Both shift and methanation reactions proceed with a single, pre-reduced and highly active catalyst.
  • No additional steam is required during operation.

+Low equipment costs:

  • Our methanator design uses no proprietary equipment.

+Design flexibility:

  • JM Davy will adjust process design and heat recovery to meet client-specific requirements.
Related Processes

Our methanation technology forms the core of our substitute natural gas (SNG) process, which can be explored by clicking the panel below:


Related Processes

Our methanation technology forms the core of our substitute natural gas (SNG) process, which can be explored by clicking the panel below: