This document discusses different technologies for clean coal energy engineering, including gas turbines, direct injection engines, and fluidized bed combustors. It provides details on the components and working of gas turbines, explaining how they compress air, add fuel for combustion, and use the expanding hot gases to power a generator. Direct injection engines are described as injecting fuel directly into engine cylinders for combustion. The document outlines two types of fluidized bed combustors - bubbling fluidized beds and circulating fluidized beds - and explains how they efficiently burn solid fuels by suspending fuel particles in hot air.