The development of photovoltaic (PV) systems and wind turbines (WT - onshore or offshore) reduces the carbon footprint (CFP) of energy generation. However, these systems deteriorate the stability of the national power system (NPS) as a result of stochastic changes in energy production. The only effectively stabilizing element of the Polish NPS are classic coal-fired power plants with turbines operating in the Rankine cycle and the combined-cycle power plants. Since the cold start-up of a coal-fired unit takes several hours, the stability of the NPS forces the boilers to operate continuously so that, if necessary, the power can be increased relatively quickly. Therefore, it will be impossible to abandon coal-fired units in the next dozen or so years, and the existing boilers will have to be modernized in order to reduce their CFP and to enable cooperation with PV and WT. These upgrades should include:
• increasing the boiler efficiency
• maintaining high efficiency and steam temperatures over a wide range of loads
• ability to operate at very low loads • increasing the rate of load change
• replacing coal (fully or partially) with a lower CFP fuel.
The last point in pulverized coal (PC) boilers is easiest to achieve by burning or co-firing biomass.
This paper deals with the assessment of the CFP for different types of biomass in accordance with the RED II Directive. It also takes into account fugitive methane emissions from coal mines. The disposable technologies of biomass burning in a PC boiler are analyzed. Example boiler calculations show the scope of necessary modernization of heating surfaces to replace 50% or more of coal with biomass. The problem of reducing harmful phenomena such as corrosion, erosion and deposits associated with such a change of fuel is also discussed.
BIOGRAPHICAL NOTEProf. dr hab. inż. Marek Pronobis is former director of the Institute of Power Engineering and Turbomachinery at the Silesian University of Technology (2009 - 2015), head of Division of Boilers and Steam Generators in this Institute (1998 - 2017). He is an expert in boilers and their auxiliary equipment. His basic scientific activity includes design calculation methods, novel heating surfaces, boilers modernization to increase their efficiency and ability to burn various fuels including biomass. He has conducted research on low-NOx combustion of fossil and renewable fuels, fouling and formation of ash deposits in boilers, erosion and corrosion processes in boilers, grinding and drying processes in solid fuel preparation installations, aluminosilicate additives improving boiler operation, as well as SCR and SNCR technology. He has published over 240 publications in scientific journals and conference proceedings, and is the author or co-author of 39 patented inventions. Monographs: Environmentally - oriented modernization of power boilers (Elsevier 2020); Wymiana ciepła w zanieczyszczonych powierzchniach konwekcyjnych kotłów (Heat transfer in contaminated convection boiler surfaces - in Polish). Zeszyty Naukowe Politechniki Śląskiej, Energetyka z.115, Gliwice 1992; Modernizacja kotłów energetycznych (Modernization of power boilers - in Polish). WNT Warszawa 2002 (9 editions), and co-author of 5 other.
He developed the concepts of many modernizations implemented in the energy sector.
In addition to his professional activity, he is still an active alpinist.