Periodic Reporting for period 3 - BELENUS (Lowering Costs by Improving Efficiencies in Biomass Fueled Boilers: New Materials and Coatings to Reduce Corrosion)
Reporting period: 2021-09-01 to 2024-02-29
Energy from biomass corresponds to more than 60% of all renewable energy sources in Europe and is currently the most widely used worldwide. Recently, the Paris Agreement in the 21st Conference of the Parties for global climate change (COP21) set the objective of global electricity production in 2050 will be almost entirely based on zero-carbon emitting technologies, so biomass energy will contribute to that objective and significantly reduce dependence of fossil fuels. However, currently biomass plants have not reached the efficiency that can be obtained with fossil fuels, mainly due to severe corrosion caused by alkali metals, chlorine and other corrosive elements, resulting in a shorter boiler components lifetime, so maximum temperatures and steam pressures are limited, which translates into lower overall efficiency and profitability. Moreover, biomass feedstock is increasingly diverse and there is a need for generic understanding of the associated corrosion risks. Today’s dominant bioenergy source is clean wood, it is expected that the share of lower cost, but more corrosive waste will increase in the future.
The BELENUS project was conducted from March 2019 until February 2024 and was funded within the H2020 program of the European Commission. BELENUS aimed at will reduce bioenergy CAPEX and OPEX through a holistic approach to prevent mainly corrosion in the boiler, in particular in superheater tubes: a) new surface engineering: biomass corrosion highly resistant coatings on creep resistance materials; b) new strategies of welding and bending for coated tubes improving the quality and efficiency of boiler components; and c) new online corrosion monitoring system specifically designed for biomass CHP plants. The project brought together a broad consortium formed of industry partners, SMEs, universities and research institutions of the biomass and materials science sector.
The new coatings, the new welding and bending strategies of the coated tubes and the corrosion monitoring system will allow raising biomass plants efficiency by increasing the operating temperature resulting in reducing the fuel expenditure and providing flexibility by allowing the use of different types of biomasses, as well as the lifetime of critical components of biomass fired boilers.
The validation tests of the new materials and developments involved lab scale, pilot plant and real plant exposure. Modelling and lifetime prediction tools and cost and life cycle analysis were undertaken so the optimum materials and coatings have been chosen from the durability, economic and environmental perspectives, maximising the sustainability in economic and environmental terms.
The BELENUS project was conducted from March 2019 until February 2024 and was funded within the H2020 program of the European Commission. BELENUS aimed at will reduce bioenergy CAPEX and OPEX through a holistic approach to prevent mainly corrosion in the boiler, in particular in superheater tubes: a) new surface engineering: biomass corrosion highly resistant coatings on creep resistance materials; b) new strategies of welding and bending for coated tubes improving the quality and efficiency of boiler components; and c) new online corrosion monitoring system specifically designed for biomass CHP plants. The project brought together a broad consortium formed of industry partners, SMEs, universities and research institutions of the biomass and materials science sector.
The new coatings, the new welding and bending strategies of the coated tubes and the corrosion monitoring system will allow raising biomass plants efficiency by increasing the operating temperature resulting in reducing the fuel expenditure and providing flexibility by allowing the use of different types of biomasses, as well as the lifetime of critical components of biomass fired boilers.
The validation tests of the new materials and developments involved lab scale, pilot plant and real plant exposure. Modelling and lifetime prediction tools and cost and life cycle analysis were undertaken so the optimum materials and coatings have been chosen from the durability, economic and environmental perspectives, maximising the sustainability in economic and environmental terms.
Among the highlights of the achievements of the BELENUS project the following points can be remarked:
A total of 30 coatings were developed by different deposition technologies. They were screening tested (500 h) under simulated fire- and steam-side. From that test, the best performing systems have been reengineered to optimize their quality and have been produced for long-term test (8000 h in fire-side and 15000 h in steamside), mechanical (tensile and erosion), welding and bending.
The optimized coatings were validated in a pilot plant under three different biomasses (eucalyptus, wheat straw and industrial wood waste. Each test was lasted 2000 h which allowed to determine differences in the corrosion mechanisms related to each biomass. Most of the work at that pilot scale was focused on biomass fuel and ash characterisation, as well as modelling of the combustion process for all the selected biomass fuels and analysing leaching procedures (not considered in the GA). In addition, studies about the biomass preparation (pelletized) and continuous feeding methodology were carried out for commissioning the pilot plant of 10 kWth was achieved.
Optimized coatings were validated in parallel in real plant. To this end, two corrosion probes were designed in the project for coatings exposure in real biomass boilers.
Coatings exposed with corrosion probes generally showed worse results than trial tube exposures, probably due to more stable heat transfer and a lower temperature gradient expected for a trial tube (temperature stability thanks to the steam).The erosion tests were essential in evaluating the Belenus coatings.
On the other hand, electrochemical sensors for on-line corrosion monitoring were developed and pre-tested in lab and pilot scale and finally validated in real plant.
In the frame of the project, it was developed a methodology to predict the lifespan of components in biomass-fired power boilers.
The environmental impact of the newly developed coatings was analysed by the tool Life Cycle Asessment (LCA).
A total of 30 coatings were developed by different deposition technologies. They were screening tested (500 h) under simulated fire- and steam-side. From that test, the best performing systems have been reengineered to optimize their quality and have been produced for long-term test (8000 h in fire-side and 15000 h in steamside), mechanical (tensile and erosion), welding and bending.
The optimized coatings were validated in a pilot plant under three different biomasses (eucalyptus, wheat straw and industrial wood waste. Each test was lasted 2000 h which allowed to determine differences in the corrosion mechanisms related to each biomass. Most of the work at that pilot scale was focused on biomass fuel and ash characterisation, as well as modelling of the combustion process for all the selected biomass fuels and analysing leaching procedures (not considered in the GA). In addition, studies about the biomass preparation (pelletized) and continuous feeding methodology were carried out for commissioning the pilot plant of 10 kWth was achieved.
Optimized coatings were validated in parallel in real plant. To this end, two corrosion probes were designed in the project for coatings exposure in real biomass boilers.
Coatings exposed with corrosion probes generally showed worse results than trial tube exposures, probably due to more stable heat transfer and a lower temperature gradient expected for a trial tube (temperature stability thanks to the steam).The erosion tests were essential in evaluating the Belenus coatings.
On the other hand, electrochemical sensors for on-line corrosion monitoring were developed and pre-tested in lab and pilot scale and finally validated in real plant.
In the frame of the project, it was developed a methodology to predict the lifespan of components in biomass-fired power boilers.
The environmental impact of the newly developed coatings was analysed by the tool Life Cycle Asessment (LCA).
The main progress beyond the state of the art can be summarized as follows:
Biomass waste fuels, materials systems, and test parameters regarding lab, pilot and plant scale and the test matrices for corrosion, erosion and mechanical testing was established. Results obtained in the screening tests carried out on the total of coatings developed indicate that most of them have promising results. However, its real-plant testing showed that the effectiveness of new materials cannot be judged solely based on results obtained in a single combustion unit. The project developed materials have not shown universal corrosion protection properties, providing protection only under certain temperature conditions and fuel composition. Therefore, the coatings should be exposed to different test environments, considering the influence of the fuel and the location of the test probes.
The experience gained during these tests performed and the validation of the on-line corrosion monitoring system, jointly with the modelling method for analysis of fouling risks in biomass boilers and the predictions about their anticipated grainsize/oxide microstructure, as well as the lifetime assessment and methodology and LCAs performed on coatings, will be a proof for investors and developers to reduce the technical uncertainty that this technology entail. Finally, the results obtained will allow the members of the consortium to offer a new solution in future CHP tenders by providing a cost competitive technology with a high level of flexibility in the energy supply and with no environmental drawbacks.
Biomass waste fuels, materials systems, and test parameters regarding lab, pilot and plant scale and the test matrices for corrosion, erosion and mechanical testing was established. Results obtained in the screening tests carried out on the total of coatings developed indicate that most of them have promising results. However, its real-plant testing showed that the effectiveness of new materials cannot be judged solely based on results obtained in a single combustion unit. The project developed materials have not shown universal corrosion protection properties, providing protection only under certain temperature conditions and fuel composition. Therefore, the coatings should be exposed to different test environments, considering the influence of the fuel and the location of the test probes.
The experience gained during these tests performed and the validation of the on-line corrosion monitoring system, jointly with the modelling method for analysis of fouling risks in biomass boilers and the predictions about their anticipated grainsize/oxide microstructure, as well as the lifetime assessment and methodology and LCAs performed on coatings, will be a proof for investors and developers to reduce the technical uncertainty that this technology entail. Finally, the results obtained will allow the members of the consortium to offer a new solution in future CHP tenders by providing a cost competitive technology with a high level of flexibility in the energy supply and with no environmental drawbacks.