Kraft recovery boilers, i.e., boilers burning pulping industry spent liquor (black liquor) and recovering pulping chemicals, generate both electricity and heat. Black liquor is the most important biomass-based energy source in Finland and worldwide.
The objective of the project is to enable the operation of Kraft recovery boilers in oxy-fuel mode. This would open opportunities for several integrated green technologies, such as bioenergy with carbon capture and storage or use.
About 220 Mtonnes black liquor are produced worldwide, with the USA as the largest with around 60 Mtonnes/year. The estimated price of an average air-fired boiler (1 Mtonnes BL/year, 1.3 Mtonnes CO2) is 200-300 MEur. The recent USA Inflation Reduction Act 2022 provides an 85 $/tonne CO2 tax credit for carbon capture, resulting in roughly 110 M$/year in tax credits – a powerful incentive.
However, the change to oxy-conditions is expected to strongly influence the overall process.
To achieve the goals, laboratory experiments on chemical details of black liquor behaviour, corrosion and material selection, kinetic modelling of emissions, CFD modelling of various processes, techno-economical aspects of the integrated processes, and process design will be carried out.
The project contributes to the TRI 6 (Integrated Industrial Energy Systems) challenges by enabling
- i) the removal of carbon emissions from the carbon cycle-negative CO2 emissions,
- ii) the integration of energy and resource-efficient industrial energy systems
- iii) carbon capture for product use.
