Process modelling for an iron oxidation CFB boiler and a powerplant water-steam cycle
Mapa, Abishek (2025)
Diplomityö
2025
School of Energy Systems, Energiatekniikka
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Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi-fe20251228125301
https://urn.fi/URN:NBN:fi-fe20251228125301
Tiivistelmä
Increasing annual energy consumption accommodates an increase in fossil fuels and greenhouse gas emissions. Renewable energy is discussed as an alternative to mitigate the negative environmental impacts of fossil fuels. Renewable energy sources such as solar power and wind power have the inherent issue of intermittent availability, and energy storage could solve this. Iron oxide redox energy storage is considered a viable storage technology due to the high availability of iron and high energy density. Although studies related to iron redox energy storage are available, studies relating to the process simulation of a commercial-scale iron combustion and power generation are limited. The thesis explains the development of a process model of the boiler and the water-steam cycle for an iron combustion case. The model uses component dimensions and operation parameters of a coal-powered CHP plant as a reference and investigates the possibility of retrofitting the reference plant with iron combustion.
The model is developed in the Apros 6 software. Heat transfer from the iron combustion reaction to the flue gas is substituted with a heat exchanger since the Apros 6 software does not facilitate metal redox reactions. Heat and power decoupling is added to the model for the district heating power to be increased with minimal impact on turbine power.
Results indicate that district heating mass flow rate and exit temperature could be matched to the reference plant’s operational cases with high accuracy, the turbine power and the district heating power show significant differences. Converting a coal powered may need to involve an extended hydrodynamic study to understand the placement and dimensioning of in-boiler heat exchangers in addition to the modifications of the combustion system. Iron as a fuel would require a larger fuel supply than coal due to the higher heating value of coal. Changes may need to be done to the supply chain to facilitate this higher fuel supply demand to ensure an uninterrupted operation.
The model is developed in the Apros 6 software. Heat transfer from the iron combustion reaction to the flue gas is substituted with a heat exchanger since the Apros 6 software does not facilitate metal redox reactions. Heat and power decoupling is added to the model for the district heating power to be increased with minimal impact on turbine power.
Results indicate that district heating mass flow rate and exit temperature could be matched to the reference plant’s operational cases with high accuracy, the turbine power and the district heating power show significant differences. Converting a coal powered may need to involve an extended hydrodynamic study to understand the placement and dimensioning of in-boiler heat exchangers in addition to the modifications of the combustion system. Iron as a fuel would require a larger fuel supply than coal due to the higher heating value of coal. Changes may need to be done to the supply chain to facilitate this higher fuel supply demand to ensure an uninterrupted operation.