Europe’s largest olive cake boiler (11 MW) is working at full capacity

A Spanish manufacturer supplied a turnkey biomass steam boiler (Eckrohrkessel design) to Europe’s largest olive oil producer, which is now working at 8.000 h/y. The biomass boiler, with an equivalent thermal power of 11 MW (15 t/h) from the by-product of the plant itself, the olive cake, as fuel for the generation of process steam, is fitted at the San Miguel Arcángel factory in the city of Jaen in southern Spain.

As known, olive cake presents problems related to its ash content and its low melting point, so a specific design of an industrial multi-pass water-tube steam boiler has been developed to counteract the effect of fouling on the heat exchange body.

Alongside the heater, the manufacturer supplied other components for the complete installation of the plant, including the combustion system with a pusher step grate, the control system and the smoke treatment system to guarantee the quality of emissions in the atmosphere. San Miguel Arcángel is the largest olive marc producer in Europe.

Sludge, slurries combustion and inorganics: a state of the art literature collection

Dirbeba, M.J., Brink, A., Lindberg, D., Hupa, M., Hupa, L., 2021. Thermal Conversion Characteristics of Molasses. ACS Omega 6, 21631–21645.

Guo, S., Gao, J., Zhao, D., Zhao, C., Li, X., Li, G., 2022. Co-combustion of sewage sludge and Zhundong coal: Effects of combustion conditions on gaseous pollutant emission and ash properties. Sustainable Energy Technologies and Assessments 54, 102836.

Ma, M., Liang, Y., Xu, D., Sun, S., Zhao, J., Wang, S., 2022. Gas emission characteristics of sewage sludge co-combustion with coal: Effect of oxygen atmosphere and feedstock mixing ratio. Fuel 322, 124102.

Manwatkar, P., Dhote, L., Pandey, R.A., Middey, A., Kumar, S., 2021. Combustion of distillery sludge mixed with coal in a drop tube furnace and emission characteristics. Energy 221, 119871.

Romanov, D.S., Vershinina, K.Yu., Dorokhov, V.V., Strizhak, P.A., 2022. Rheology, ignition, and combustion performance of coal-water slurries: Influence of sequence and methods of mixing. Fuel 322, 124294.

Strandberg, A., Skoglund, N., Thyrel, M., 2021. Morphological characterisation of ash particles from co-combustion of sewage sludge and wheat straw with X-ray microtomography. Waste Management 135, 30–39.

Wang, T., Lou, Y., Jiang, S., Wang, J., Zhang, Y., Pan, W.-P., 2022. Distribution characteristics and environmental risk assessment of trace elements in desulfurization sludge from coal-fired power plants. Fuel 314, 122771.

Wang, Y., Jia, L., Guo, B., Wang, B., Zhang, L., Zheng, X., Xiang, J., Jin, Y., 2022. Effects of CaO-Fe2O3-Fe3(PO4)2 in sewage sludge on combustion characteristics and kinetics of coal slime. Fuel 322, 124267.

Zhang, D., Ma, T., 2022. Study on slagging in a waste-heat recovery boiler associated with a bottom-blown metal smelting furnace. Energy 241, 122852.

Zheng, L., Jin, J., Liu, Z., Kou, X., He, X., Shen, L., 2022. Ash formation characteristics in co-combusting coagulation sludge and Zhundong coal. Fuel 311, 122571.

Zhou, A., Ma, W., Ruan, R., Li, Y., Zhang, Q., Mao, R., Yu, S., Deng, S., Tan, H., Wang, X., 2022a. Experimental study on PM10 formation characteristics of co-combustion with pulverized coal and sludge. Fuel Processing Technology 236, 107438.

Zhou, A., Wang, X., Magdziarz, A., Yu, S., Deng, S., Bai, J., Zhang, Q., Tan, H., 2022b. Ash fusion and mineral evolution during the co-firing of coal and municipal sewage sludge in power plants. Fuel 310, 122416.

Where will the dispatchable power come from, after the coal phase-out?

Where will the dispatchable power come from, after the coal phase-out?

  • Conventional -> Natural gas.
  • Storage -> Pumped storage hydro; Battery storage.
  • Renewables -> Biomass, biogas, green gases (H2, CH4, etc.).

What about the coal phase out in the EU, from the regulator perspectives (data and animation courtesy of Climate Analytics)?

Detail for Italy (example)

Unit Name Opening year Closing year Regulator Closing year Market
Italy Brindisi Nord power station Unit 3 1979 2024 2020
Italy Brindisi Nord power station Unit 4 1979 2024 2020
Italy Pietro Vannucci power station Unit 1 1989 2024 2020
Italy Pietro Vannucci power station Unit 2 1990 2025 2020
Italy Andrea Palladio power station Unit 3 1974 2025 2025
Italy Andrea Palladio power station Unit 4 1974 2025 2025
Italy Sulcis power station Unit 3 1986 2026 2028
Italy Fiume Santo power station Unit 1 1992 2026 2028
Italy Fiume Santo power station Unit 2 1993 2026 2028
Italy Sulcis power station Unit 2 2005 2026 2028
Italy Porto Marghera Alsar power station Unit 1 1977 2027 2020
Italy Palermo (B) 2004 2027 2020
Italy Brescia 3 1988 2027 2028
Italy Brindisi Sud power station Unit 1 1991 2028 2028
Italy Brindisi Sud power station Unit 2 1992 2028 2028
Italy Brindisi Sud power station Unit 3 1992 2028 2028
Italy Brindisi Sud power station Unit 4 1993 2028 2028
Italy Torrevaldaliga Nord power station Unit 1 2009 2029 2020
Italy Torrevaldaliga Nord power station Unit 2 2010 2030 2028
Italy Torrevaldaliga Nord power station Unit 3 2010 2030 2029

The EU Biofficiency project (2016-2019): executive summary

The EU funded project Biofficiency developed some tests on pre-treated fuels and a blueprint for the modern biomass cogeneration plants. We summarize the key conclusions which relate to fuel ash.

  • Additives and materials
    • Deposits tests in PF boilers to reduce deposition showed that the additive amount has a greater important than the type of additive. In particular, within the 4 MW CFB tests, elemental S was found to be the most cost-effective additive (with respect to kaolin). 200 kW tests showed that in PF beech wood combustion with 1% kaolin decreased PM1 emissions by 33%; by 75% with 2.4% kaolin.
    • 800 MWth CHP Avendore U2 and Studstrup U3 tests showed that coal fly ash addition decreased the submicron aerosol particles, but kept the K-Ca-S sintered downstream deposits (sootblowing was maintained). SH Cl corrosion on TP347H/HFG, SUPER 304H, Esshete 1250 was mitigated with 2,5% coal fly ash addition, but corrosion by sulphidation was observed.
    • With lab tests to test high steam temperature, at 650°C, only the austenitic SS TP310HCbN survived to heavy KCl corrosion.
  • Pre-treatments
    • Torrefaction increased the ash content without causing compositional changes, but if followed by a washing step it decreased alkali and Cl content, consequently increasing ash melting temperatures.
    • Steam explosion did not induce significant ash compositional changes, a slightly decreased ash melting temperature was found.
    • Hydrothermal carbonization decreased alkali and Cl content, yielded high Si-ashes and higher melting temperatures.
    • Detailed fuel and ash data are now publicly available and those could be used in our numerical modelling.
  • State of the art PF power plant design expected at 2.7 k€/kWel: 300 MWth, 560°C steam temperature and 92-94% efficiency, fuelled by wood pellets, dry de-ashing with ash recirculation, additivation with coal fly ash for SH and Denox SCR reactor protection including ash utilization oriented plant operation.