Control design for CFB boilers integrated with process design

Thesis event information

Date and time of the thesis defence

Place of the thesis defence

Linnanmaa, auditorium L6. Remote connection: https://oulu.zoom.us/j/62524983458

Topic of the dissertation

Control design for CFB boilers integrated with process design

Doctoral candidate

Master of Science (Technology) Matias Hultgren

Faculty and unit

University of Oulu Graduate School, Faculty of Technology, Systems Engineering, Intelligent Machines and Systems Research Unit

Subject of study

Process Engineering

Opponent

Associate Professor Pál Szentannai, Budapest University of Technology and Economics (Hungary)

Second opponent

Doctor Peter Singstad, Cybernetica (Trondheim, Norway)

Custos

Docent Jenő Kovács, University of Oulu

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More sustainable power generation in the electrical grid through the combined control and process design of power plants

Current environmental challenges place great demands on the reduction of emissions in society. This calls for a significant increase in renewable energy generation, but temporal changes in the output of solar and wind power, for example, also make balancing the power grid challenging. Because of this, combustion power plants capable of performing large and fast load changes in electrical power are also needed to ensure steady power generation. At the same time, these power plants should aim at reduced emissions, which leads to new process modifications. The design of flexible and low-emission combustion power plants thus differs substantially from conventional power plant design where economic performance at the maximum load level is emphasized.

Improved electrical power load changes and a greater flexibility for process modifications were obtained for circulating fluidized bed boilers through integrated control and process design in this thesis research work. Process and control design are conventionally performed sequentially for industrial processes like power plants. As a result, the process design places restrictions on the control of the generated electrical power. This limitation can be avoided effectively by increasing the interaction between the design stages through integrated design. It is proposed in the doctoral research that integrated design is an essential development for combustion power plants like the circulating fluidized bed boiler. The combination of control and process design was done now for fluidized bed boilers for the first time.

A three-stage integrated design procedure was defined for fluidized bed boilers in the research work, with the stages being process analysis based on simulation and state estimation, control structure selection based on interaction analysis, and simultaneous optimization of process and controller parameters. The research results showed that accurate load changes could be reached in the circulating fluidized bed boiler through the chosen methods, and the boiler could be modified to be suitable for oxy-combustion, which is a technology for capturing carbon dioxide emissions. The design guidelines presented in the research work thus enable more sustainable power generation in the grid.
Last updated: 30.11.2021