INITIAL SITUATION
Many energy-intensive industries still lack economically viable solutions for reducing greenhouse gas emissions. CCS and CCU are economically viable only in large-scale applications. One promising approach is to replace fossil coal and natural gas with biochar and renewable pyrolysis gas.
Biochar is usually produced from biomass through slow pyrolysis processes. Although these technologies are well established, they have significant drawbacks that make them unattractive for industrial applications: batch processing, inadequate pyrolysis gas quality and limited energy efficiency. The mixture of tar and hydrocarbons contained in the pyrolysis gas prevents its direct use—even though it accounts for around 50% of the calorific value supplied by the feedstock. This is precisely where the project comes in.
PROJECT OBJECTIVE
The aim is to develop an innovative continuous process that produces high-quality biochar and pyrolysis gas suitable for energy use, with very low pollutant emissions and a raw-material conversion efficiency into marketable products of over 90%.
The concept is based on a continuously operated counter-current fixed-bed biomass pyrolysis process (CCFBP), directly coupled with plasma-based pyrolysis gas treatment and a novel high-temperature tar reforming catalyst (HT-TRC).
This is intended to make the pyrolysis gas suitable for direct use in gas engines, gas turbines or industrial gas burners. One advantage of the CCFBP process is that it produces pyrolysis gas that is virtually dust-free, opening up new approaches to tar reforming. The feedstock will consist of abundant, low-grade biomass waste; the technology is being developed for a production capacity of up to 2,000 tonnes per year.
OUR SOLUTION
PlasmaAir AG is developing the plasma torch, which forms the heart of pyrolysis gas treatment and is specifically designed to use water vapour as the plasma gas. This choice is crucial to its operation and is based on two reasons:
Avoiding unwanted side reactions: Unlike air plasma, this prevents the thermal formation of NOx and oxidation with O₂.
Improved tar reforming: Water vapour plasma generates H, O and OH radicals, which actively improve the reforming of tar in the pyrolysis gas.
Increasing the hydrogen content by up to 20%.
PlasmaAir’s contribution includes developing the torch and integrating it into the pyrolysis gas reactor as a coordinated overall system:
an arc-heated plasma torch with a simulation-optimised torch geometry,
a torch cooling system that feeds its heat into the pyrolysis gas heat recovery system,
a CFD-optimised mixing zone and a thermal conversion zone for the tar,
working in conjunction with the newly developed high-temperature catalyst.
This enables the project partners to develop an integrated reactor that converts previously difficult-to-use pyrolysis gas into a high-quality energy carrier that can be used for energy – and, for the first time, deploys a plasma-assisted system in biomass pyrolysis.
