Course syllabus

MEN120 Heat and power systems engineering (7.5 hp)

Link to weekly overview of course activities

Course is offered by the department of Space, Earth and Environment

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To mitigate climate change, and to work towards a more sustainable society, actions are needed across all sectors e.g. including agriculture, industry and transportation. The focus for this course is on thermal heat and power production plants. Even though the share of renewable power production has increased, the fossil-based power plants are, both globally and from a European perspective, still responsible for the main share of power production. The high share of intermittent sources has, however, caused changes in operational patterns of thermal power plants. Thermal power plants originally designed for base load power generation will now need to act as top load plants. As top load plants they have to ramp up and down to follow the demand. Combined cycle thermal power plants might even need to start-up and shut down on daily basis or several times over the course of a week, even if they were conceived for base load generation. Therefore, flexible and transient operation is becoming of increasing importance in thermal power generation. Such a transient operation will have a huge influence on the performance of the plant affecting efficiency as well as emissions.

Switching from coal to biogenic and waste derived fuels are one of the proposed ways to reduce CO₂ emissions from power generation and industrial furnaces. Due to the different composition between coal and these other fuels, it is, however, not only a question of switching fuel, but also how to handle the problems that arise. One such problem is the high temperature corrosion (HTC) which is a problem that affects the heat transfer surfaces in a boiler. HTC is caused mainly by alkali-based salts that easily are deposited on heat transfer surfaces and are also corrosive. Compounds that contain alkali metals and chlorine are among the most aggressive agents, which is why HTC is primarily a problem for power plants that are fired with bio- and waste-fuels rather than coal.

A second alternative to significantly reduce CO₂ emissions is to apply carbon capture where the CO₂ is separated from the flue gas and later used or stored to prevent it to be emitted to the atmosphere. An interesting alternative is to combine combustion of biogenic fuels and carbon capture which has the potential to reduce the atmospheric CO₂ concentration. The capture part can be performed in different ways but always comes with an extra energy requirement reducing the efficiency and increasing the investment and operational cost compared to not applying carbon capture.

A significant effort is required in the heat and power production sector to be able to adopt to the new situation it is facing and at the same time keep emissions like SO_X, NO_X and particulates below emission limits during a transition phase towards zero emission control systems, that is, systems that are not yet commercially adopted. The plant design is important in order to find solutions. In this course the design opportunities of modern power plants will be discussed as well as the potential of modernizing older power plants. This is done by looking into the design of coal, natural gas and waste or biomass based combined heat and power plants. Their similarities and differences will be discussed from a thermodynamic point of view. Theoretical knowledge gained will then be applied in a project work, consisting of simulations of these different power plants. When building different models, the students will be able to see how the performance of a power plant changes by, for example, adding a carbon capture unit or switching fuel from coal to biomass. Combined with the theoretical background given during lectures the student will also understand why the power plant behaves in a certain way and be able to evaluate different thermal power plants with respect to overall performance, regional energy system and emission regulations.