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VTT and Valmet Technologies develop infrared imaging for the bio-oil pyrolysis plant BFB furnace


​Joensuu bio-oil plant [Valmet Corporation]

VTT, together with Valmet Technologies, is developing an in-line method for monitoring the bio-oil pyrolysis plant bubble fluidized bed (BFB) furnace. The method is based on high-speed infrared imaging technology, which enables fast and accurate assessment of combustion quality and temperature distributions in different parts of the BFB boiler. This collaboration is a part of a larger research and development project, in which a completely new kind of bio-oil pyrolysis plant is being built in Joensuu, Finland.

VTT has developed an infrared imaging system that consists of a mid-infrared range camera with a photodetector cooled to a temperature of -200°C that provides high-end speed and accuracy for furnace monitoring. The focus of this development work is to detect combustion processes and temperature distributions in different parts of the BFB furnace with infrared imaging.

"Working with VTT has given us insight into new technologies that can be used in the research of both combustion- and pyrolysis-related phenomena," says Product Manager Joakim Autio from Valmet.

The first industrial-scale bio-oil production plant was commissioned in Joensuu, eastern Finland, in 2013. The plant, which has been integrated with Fortum's Joensuu combined heat and power plant (CHP), will produce 50,000 tons of bio-oil annually from wood-based fuels, in addition to electricity and district heat. This annual production corresponds to the heating needs of about 10,000 households. This integration of the bio-oil plant with an existing heat and power plant is unique in the world.

Valmet (Metso until 31 December 2013) supplied the plant to Joensuu as a turnkey delivery, including the foundations and buildings, feedstock reception and pre-treatment, pyrolysis system, bio-oil storage tanks and loading equipment, as well as a Metso DNA automation system and electrification. The delivery also included installation, testing and training.

Since 2007, Valmet has been researching integrated pyrolysis technology to enable conversion of the fluidized bed boilers used in power plants into biorefineries. The forest products company UPM, the utility company Fortum and VTT Technical Research Centre of Finland have also been involved in the project, which has received financing from Tekes, the Finnish Funding Agency for Technology and Innovation.