Supporting its landfill diversion efforts, Victoria-based City Circle Group has built a timber gasification plant to power its concrete crushing operations.
More than 95 per cent of construction and demolition (C&D) waste generated in Melbourne is recycled and reused in civil construction infrastructure projects, helping to divert more than 5 million cubic metres of this material from landfill each year.
Victoria-based demolition company City Circle Group was an early instigator of C&D materials recycling. Since the mid-1990s, it has recovered concrete, rock, masonry and brick rubble to process into a range of quality recycled products, including VicRoads specification road base and pavement.
In general, waste wood products take up a significant proportion of landfill space around Australia. Some is recovered and reprocessed for use in timber products and for landscaping, but the majority is consigned to landfill.
City Circle’s building demolition business generates large volumes of waste timber, around 10,000 tonnes annually, which it used to dispose of in landfill.
Alan Bloomfield, Recycling Manager, explains how the company was looking for a better solution for this significant waste stream. It decided upon building a gasification plant to use the timber to generate electricity, which would power its concrete crushing and recycling operation at its Brooklyn site.
“Timber waste can be converted through gasification to produce a gaseous fuel for generation of electrical energy,” says Alan. “Our gasification facility is designed to divert demolition waste timber from landfill and supply 1.0 megawatts of electrical energy to power our C&D waste concrete recycling plant.”
Commissioning was undertaken in stages, starting with the gasifier section in November 2015. The plant is now operating as a research and development facility while being prepared for commercial use.
Bringing the plant to life
Conceptual design and planning for the gasification facility got underway in 2009. City Circle approached Ken Holland of Steam Systems to design the plant to convert waste timber coming from demolition projects to energy for use at the Brooklyn site, and to trial the gasification process for conversion of other combustible wastes for future development in larger scale commercial applications.
Ken has over 40 years’ experience in best practice timber combustion technologies, and has been a leader in the development of environmentally sound waste timber disposal methods throughout the timber industry.
“The use of under-grate combustion systems in water tube boilers supported advances in biomass gasification systems,” says Alan.
“The technology can process high moisture content timbers in compliance with stringent Environmental Protection Standards for emission control.”
The project was set to cost $1.8 million. City Circle was helped to get the scheme off the ground with a grant of $500,000 from Sustainability Victoria. Work on its fabrication and installation at Brooklyn started in 2013.
The plant was built to a modular design, with the different elements housed in four six-metre shipping containers. The gasifier and heat exchangers are enclosed in a modified container with two ventilated roll-up doors.
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