Oxy-Kraft recovery boiler – Towards novel integrated green energy parks

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 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 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 behavior, corrosion and material selection, kinetic modeling of emissions, CFD modeling of various processes, techno-economical aspects of the integrated processes, and process design will be carried out.

CETPartnership project

This project originates from a call within the Clean Energy Transition Partnership (CETPartnership), a multilateral and strategic partnership between national and regional research, development, and innovation programs in EU member states and associated countries, with the aim of promoting and accelerating the energy transition and supporting the implementation of the European Strategic Energy Technology Plan (SET).

The project specifically contributes to the TRI6 challenges by enabling

• the removal of carbon emissions from the carbon cycle-negative CO2 emissions
• the integration of energy and resource-efficient industrial energy systems
• carbon capture for product use.

Organisation

The project is coordinated by Åbo Akademi University in Finland. The participation of KTH Royal Institute of Technology is supported by the Swedish Energy Agency. There are several partners in the project.