how does an incenerator works?

Answer 1

A large incinerator (big enough to do tons of municipal trash every week) has an unloading dock where trash vehicles dump their loads down onto a large floor. That trash is then pushed into a chamber where waste heat from the process can be used to dry the trash to avoid smoke and combustion failure. It is then pushed down into a combustion chamber where a combination of the burning pile and gas or oil burners set the pile ablaze. The fire is usually monitored to make sure there are not flareups from strong combustibles in the garbage. Otherwise it burns and the smoke is passed through scrubbers that eliminate soot and noxious fumes. The burnables are raked into piles to cool and then be carted away to landfills.

Answer 2

An incinerator is a chamber that uses flame and fire to burn up (incinerate) any material placed inside.
The heat generated by the burning of the material can be used to drive steam turbines or other machines to generate electricity (though that is not the main purpose of an incinerator).