Power Plant Engineering Practice Test: Combustion Mechanism, Equipment & Firing Methods — Flashcards

Combustion Mechanism, Equipment & Firing Methods topics include: Pulverisation and gasifiers, kinetic and diffusion control and coal firing systems.

The combustion mechanism in a power plant involves burning fuels like coal, oil, or gas to generate heat energy. This heat is used to create steam, which drives turbines to generate electricity. The steam is then cooled and condensed back into water, which is reused in the process. 

Here's how the combustion mechanism works in different types of power plants:
Thermal power plants: Fuels like heavy oil, LNG, and coal are burned inside a boiler to generate steam at high temperature and high pressure. This steam is used to rotate the impeller of the steam turbine. This drives the power generators connected to the turbine that generate electricity.
Gas turbine power plants: The combustion produces a high temperature, high pressure gas stream that enters and expands through the turbine section. As hot combustion gas expands through the turbine, it spins the rotating blades.
Combustion turbine power plants: The combustion occurs immediately, allowing gases to then expand through turbine blades connected to a generator to produce electricity. Combustion turbine power plants are normally run on natural gas as a fuel. 

Combustion systems that use hydrocarbon fuels produce carbon dioxide (CO2) and water vapor (H2O) due to the oxidation of carbon and hydrogen. Although CO2 and H2O are considered non-toxic, they are greenhouse gases and have been associated with global warming.

Here are some firing methods used in power plants:
Biomass co-firing: A boiler blends and combusts biomass with other fuels, like coal or natural gas, to generate electricity.
Supplementary firing: Can increase the amount of heat and electricity generated by a steam turbine when gas turbine loads are 80% or more.
Boiler firing: In a conventional power plant, fuel is burned in a boiler to create a high-pressure system. The steam then drives a turbine to produce electricity.
Oxidation firing: Typically done in an electric kiln, but can also be done in a gas kiln. Oxygen is free to interact with the glazes when firing.
Burning crude oil: When burned in an oil-fired power plant, crude oil can heat water past its boiling point to produce steam, which can be used to spin turbines in order to generate electricity.