www.wwtonline.co.uk | WWT | NOVEMBER 2017 | 21
• ATC GASIFICATION: HOW IT WORKS
• The sludge from the wastewater treatment works at Lower
Brighouse is brought into the adjoining advanced thermal conversion
(ATC) plant as cake of around 22% dry solids. It is fed into a low
temperature STC drier, supplied by Suez, where it is dried on a belt at
a temperature of 70-80 degrees, and shaped into pellets
• The pellets are then mixed with pelletised wood, in a proportion of
30% sludge and 70% wood. The aim is to create a fuel for the gasifier
which is as uniform as possible; however, the proportions can be
changed if required, with up to 50% sludge content possible
• The pellets then enter the gasifier, where they are kept moving
continuously through the unit with hot air meeting the fuel. The
temperature is kept carefully controlled, and unlike other gasifier
models, there is no grate which can become clogged. Hydrocarbons in
the fuel are converted into hydrogen and carbon.
• This process produces syngas, which is around 20% hydrogen, 20%
carbon monoxide and 2% methane. This is fed into two Jenbacher
CHP engines which create electricity and heat.
• The heat is conveyed back to the sludge drier where it helps earlier
in the process; the electricity is taken to a grid connection or private
wire connection
• The process also produces char, which is largely carbon and sludge
ash. This material can be used as a coal substitute, and Yorkshire
Water have identified possible users for this. Research is also
underway to discover if the carbon can be activated for use elsewhere
in the wastewater treatment process
You can find out more about Yorkshire Water's ATC gasification
plant when Jon Brigg presents at WWT's Water Industry Technology
Innovation conference in Birmingham on November 30th.
Details: events.wwtonline.co.uk/innovation
L-R: Jon Brigg (Yorkshire Water), David Pitt, Eriks Samulis (both Enertecgreen), John Shepherd (Yorkshire Water)
The sludge is dried on a belt and shaped into pellets
The Enertecgreen gasifier
