Power Plant Boilers: Water and Steam

State the purposes of water circulation in a boiler. Describe the water flow path through a typical drum-type boiler. Describe the basic principle of natural circulation and two factors that can affect it. Describe the differences between natural and controlled circulations. Describe the functions and components of a typical boiler drum. Define the following terms : “boiling,” “saturation,” “temperature,” and “superheat.” Describe the steam flow path from the boiler to the condenser in a typical generating unit. State the function of a superheater and describe how superheaters can be classified. State the function of a desuperheater. State the function of a reheater and describe how reheaters can be classified. Describe the basic operation of a condenser. Define the term “critical point.” Explain why some boilers operate above the critical point. Describe the flow path of water in a once-through boiler. State the advantages and disadvantages of a once-through supercritical boiler. Explain how steam pressure is maintained in drum-type and once-through boilers.