What is bottom ash in relation to coal combustion?

Bottom ash is the residue that remains after coal is burned in a furnace. During the combustion process, coal is heated to high temperatures, leading to the formation of various byproducts, including ash. The bottom ash specifically refers to the solid particulate matter that drops to the bottom of the combustion chamber or furnace due to its heavier weight compared to other combustion byproducts.

In coal-fired boilers, when the coal is burned, the lighter particles and gases rise into the flue gas stream, while the denser particles settle to the bottom. This settling occurs because the bottom ash is heavier and tends to fall out of the combustion zone. Managing bottom ash is important in power generation, as it can be hazardous and must be handled and disposed of properly.

Understanding the distinction between bottom ash and other types of ash, such as fly ash (which is carried up with the flue gases), is essential in coal combustion processes, as their applications and environmental impacts differ significantly.