What is the energy transformations in coal used to make electricity?

Answer 1

I am writing down the entire process of how a thermal power plant works, along with a summary.

1. Coal supply - After haulers drop off the coal, a set of crushers and conveyors prepare and deliver the coal to the power plant. When the plant needs coal, coal "hoppers" crush coal to a few inches in size and conveyor belts bring the coal inside.
2. Coal pulverizer - The belts dump coal into a huge bin (pulverizer), which reduces the coal to a fine powder. Hot air from nearby fans blows the powdered coal into huge furnaces (boilers).
3. Boiler - The boiler walls are lined with many kilometres of pipe filled with water. As soon as the coal enters the boiler, it instantly catches fire and burns with high intensity (the temperatures inside the furnace may climb to 1,300° C). This heat quickly boils the water inside the pipes, changing it into steam.
4. Precipitators and stack - As the coal burns, it produces emissions (carbon dioxide, sulphur dioxide and nitrogen oxides) and ash.The gases, together with the lighter ash (fly ash), are vented from the boiler up the stack. Huge air filters called electrostatic precipitators remove nearly all the fly ash before it is released into the atmosphere. The heavier ash (bottom ash) collects in the bottom of the boilers and is removed.
5. Turbine and generator - Meanwhile, steam moves at high speed to the turbines, massive drums with hundreds of blades turned at an angle, like the blades of a fan.As jets of high-pressure steam emerge from the pipes, they propel the blades, causing the turbine to spin rapidly. A metal shaft connects the turbine to a generator. As the turbine turns, it causes an electro-magnet to turn inside coils of wire in the generator. The spinning magnet puts electrons in motion inside the wires, creating electricity.
6. Condensers and cooling water system - Next, the steam exits the turbines and passes over cool tubes in the condenser. The condensers capture the used steam and transform it back to water. The cooled water is then pumped back to the boiler to repeat the heating process. At the same time, water is piped from a reservoir or river to keep the condensers constantly cool. This cooling water, now warm from the heat exchange in the condensers, is released from the plant.
7. Water purification - To reduce corrosion, plants purify water for use in the boiler tubes. Wastewater is also treated and pumped out to holding ponds.
8. Ash systems - Ash is removed from the plant and hauled to disposal sites or ash lagoons. Ash is also sold for use in manufacturing cement.
9. transformer and transmission lines - Transformers increase the voltage of the electricity generated. transmission lines then carry the electricity at high voltages from the plant to substations in cities and towns.

Summary: In a thermal power plant, the coal is first crushed into fine powder (there is no energy change yet in coal, as the chemical energy inside it is unchanged). Then, the powdered coal it is added to a furnace, where it is set on fire. Many tubes containing water pass through the furnace. This water boils and turns to steam. Now, the chemical energy of the coal has turned into kinetic energy of the steam. The steam is passed through turbines, which causes them to rotate. The kinetic energy of steam turns to kinetic energy of turbines. Turbines are connected with a dynamo's/generator's shaft and causes the shaft to rotate, which in turn rotates a magnet surrounded by metal wire coils. This produces electricity.