In CHEERS, the verification of oxygen carriers is an integrated activity. Oxygen carriers should be capable of sustaining the exceedingly high sulphur and metals contents associated with e.g. petcoke. The interaction between oxygen carriers and the petcoke gasification/burn-out is vital to the process efficacy. This interaction may also cause critical agglomeration and sulphur passivation. Three oxygen carriers (natural ore) have been tested at pilot scale (up to 150kWth). All of them performed well, but a particular ilmenite material from Titania in Norway has been chosen for use in the 3MW demonstration unit. A total of 300 tons of the oxygen carrier was transported to China, sieved, and used in the demonstration unit.
A cold-flow mock-up of the demonstration unit has been designed, constructed, tested, and used for design validation and training of operators. In particular, hydrodynamic studies of the air reactor, L-valves and sections of the fuel reactor were performed and found to fit with design expectations. Based on this, the Front-End Engineering and Design (FEED) of the 3MW demonstration unit, consisting of 250 deliverables, was finalized by the engineering company WORLEY. After completion, FEED handover from TOTAL to DONGFANG was organized between May and July 2021 to start the Engineering Procurement Construction and Commissioning (EPCC) phase. The EPCC consisted of a large number of sub-contracts for e.g. civil engineering, environmental assessment, long lead items (reaction section and flue gas management), control system, etc. The EPCC phase was finalized in April 2023, which kicked off the start-up phase in May 2023. During the period May-October 2023, several start-up attempts were made. Unfortunately, during this period, it became clear that the current refractory was not strong enough to withstand the harsh conditions in the fuel reactor. This led to significant heat-loss, which again meant that it was not possible to reach the high temperatures needed to successfully switch to CLC-mode. The refractory was therefore re-done based on a castable approach. With this new refractory, new tests were done in March 2024, where full autothermal CLC-mode with lignite as fuel was demonstrated. During these tests, a carbon capture efficiency as high as 90-94% was achieved, while the oxygen demand was as low as 2.5-3%. In addition, autothermal CLC-mode was also achieved with a fuel consisting of a mix of petcoke and lignite (40/60w%). The petcoke used in the tests had a size distribution not corresponding to the design value, leading to excessive char loss from the fuel reactor and preventing autothermicity during CLC mode operation.
Several modelling approaches have been developed for the demonstration unit. A simplified one-dimensional model has been used for system optimization, while a full three-dimensional CFD model was used to understand the behaviour inside the reactors in more detail. CFD simulations of the 150 kW pilot unit in Trondheim and the cold mock-up in Deyang have been finalized and compared with experimental results. These simulations served as validation of models being used. CFD simulations of the demo unit have also been initiated, simulating the whole reactor system including cyclones, but this work is not yet finalized.
Process simulations of CLC, CFB and NGCC cases at industrial scale, both for refinery and power applications, have been performed. The results were used as the basis for the techno-economic analysis of the three technologies (CLC, CFB and NGCC). The main conclusion from this analysis was that for pet-coke, but probably also for all other solid fuels, the CLC technology was significantly more energy efficient than CFB with post-combustion capture.
A webinar series presenting the main results from the various work performed in the project has been organized. The dissemination of results within the scientific community and the wider public have contributed to increased visibility of Horizon 2020 projects and promoted cooperation between the EU and China.
The final event of CHEERS, together with the inauguration of the demo unit, was successfully organized in Deyang, China, in September 2023.
