PSO Project 10085: Final Report – Co-Firing of Coal and RDF in Suspension

Co-combustion of refuse derived fuels (RDF) with coal in pulverized coal-fired power plants can potentially increase the electrical efficiency of utilizing RDF and reduce the formation of some harmful pollutants such as dioxins. The objective of this project was to provide a general assessment of the technical issues related to co-combustion of coal and RDF, and to improve the fundamental understandings of this subject.

The project was carried out in collaboration between the CHEC Research Centre at DTU Chemical Engineering and DONG Energy Power A/S, and was financially supported by Energinet.dk. The project work mainly involved conducting pilot-scale experiments in the CHEC entrained flow reactor, carrying out full-scale aerosol measurements at the Esbjergværket (ESV), doing global equilibrium calculations, and performing thermogravimetric experiments.

Through performing co-combustion experiments in the CHEC entrained flow reactor, the burnout, NO and SO2 emissions, the transformation of ash forming species, the formation of deposits, and the partitioning of trace elements during co-combustion of coal and solid recovered fuel (SRF) were studied systematically.

The effect of different coal properties, SRF properties, and mass share of SRF on co-combustion was investigated. Besides, global equilibrium calculations were conducted to interpret the results of the entrained flow experiments. The formation of fine particles during cocombustion of coal and SRF was also investigated, through performing full-scale aerosol measurements at the Esbjergværket (ESV).

The influence of co-combustion on the concentration and composition of the fine particles was evaluated, and the impact on the dust emissions was discussed. In addition, a fundamental study on the interactions of coal and different waste materials during pyrolysis was conducted through thermogravimetric experiments.

In general, the results obtained from this project have significantly improved the understandings of fuel conversion, ash transformation, ash deposition, and pollutant formation during co-combustion of coal and refuse derived fuels. These results have also provided essential knowledge regarding the fuel selection and process optimization of co-firing refuse derived fuels and coal under suspension-firing conditions.