CBG’s water-wash process – clearly the biogas upgrading technology of choice


FLI Energy has selected Chesterfield Biogas Ltd (CBG) to supply the upgrader for biogas produced by a new anaerobic digestion plant (AD) being built at Ellough, near Beccles, Suffolk.

A principal determining factor in the award of the contract is said to be that CBG is a UK-based company. Support services are on hand from its headquarters in Sheffield, South Yorkshire. 24/7 monitoring, plus a planned maintenance programme – to ensure the upgrader’s efficiency in the years ahead – form part of the contract. Spares for key parts will be held in the UK.

In 2010, at the sewage treatment plant of Thames Water in Didcot, CBG supplied the biogas unit central to the UK’s first successful injection of upgraded biogas to the grid.

Since then CBG has played a leading role raising the awareness of the benefits of the technology in the UK. The company has developed special technical expertise in relation to the different organic feedstocks which can be processed by the AD plant and which may affect the content of the raw gas sent to the upgrader.

At the Beccles plant, feedstock for the will be energy crops. On other projects, CBG’s water-wash units have been shown to be adaptable to a variety of feedstock inputs – anything from maize, food waste or tomato tops to treated sewage and mixed waste.

The basis for this assurance is that the same water-wash process has been developed over the last 20 years, with some sites operating successfully for more than a decade – particularly in Scandinavia, Germany, Canada and the Far East.

At Beccles, CBG will supply, install and commission a Greenlane® ‘Totara’ model with an anticipated gas throughput requirement of between 600 Nm3/hr and 2000 Nm3/hr. There are 29 installations of this model already operating successfully at sites around the world.

Like all the upgraders in the range, the ‘Totara’ is of modular design using standardized componentry. Five ‘Totaras’, coupled in series, have been successfully operating what is currently the world’s largest biogas upgrading plant (by gas throughput volume) at Guestrow in Germany. A site currently commissioning in Canada will employ ‘Totaras’ to process even larger volumes of gas.

The unit can accept the biogas from the digester with no pre-wash. No process chemicals and no heat input are required. Both CAPEX and OPEX ratios are said to be highly competitive.

Gas grids and infrastructure vary from country to country. In the UK, the CBG process meets the Gas Safety Management Regulations and HSE requirements under which UK gas-to-grid contracts are framed – for example, in achieving the allowable oxygen content of the gas.

Managing Director of Chesterfield BioGas, Stephen McCulloch says of the contract award:

We have been working in partnership with FLI Energy for some months to develop this, our second new UK contract within a few weeks. We view all such projects as a partnership process because, while the upgraders that we offer are modular, ‘plug-and-go’ systems, all sites have their particular requirements and constraints.
We are aware that the support package has been an important factor in our clinching this contract.

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Tags: Chesterfield Biogas, FLI Energy