$9.\_\_\_\_\_$ stokers handle the automatic feeding of coal, are capable of high $\_\_\_,$ and ensure a more $\_\_\_\_\_,$ thus reducing manual labor and improving combustion control.

A$)$ Mechanical, combustion rates, efficient burn

B$)$ Manual, heat output, turbulent mix

C$)$ Automated, fuel consumption, stable operation

$10.$ In fluidized bed combustion systems, the use of $\_\_\_\_\_,$ a process involving $\_\_\_,$ helps reduce the emission of sulfur dioxide by capturing it as $\_\_\_\_\_.$

A$)$ limestone$,$ chemical binding, calcium sulfate

B$)$ catalysts, filtration, sulfuric acid

C$)$ scrubbers, adsorption, solid waste

$11.\_\_\_\_\_$ burners are specifically designed to minimize the formation of $\_\_\_,$ by optimizing the mixture of $\_\_\_,$ and using advanced $\_\_\_\_\_$ technologies.

A$)$ Low$-$NOx, nitrogen oxides, air and fuel, combustion control

B$)$ High$-$efficiency, carbon monoxide, fuel, filtration

C$)$ Ultra$-$clean, particulates, oxygen, catalytic

$12.$ Performing a heat balance in a combustion process involves calculating the energy supplied by the $\_\_\_\_\_,$ the useful energy output, and the losses through $\_\_\_,$ and $\_\_\_\_\_.$

A$)$ fuel, exhaust gases, unburnt residues

B$)$ burner, radiation, conduction

C$)$ system, flue gases, system inefficiencies