The auxiliaries breathe life into an otherwise static boiler made of pressure parts (PPs) and nonpressure parts (NPPs). The auxiliaries, generating and regulating the flows, are present in the following two circuits:

1. Air and gas circuit that comprises

A. Fans

B. Dust-collecting equipment

C. Dampers

2. Steam and water circuit that comprises

A. Feed pumps and circulation pumps

B. Valves, mountings, and fittings

C. Soot blowers (SBs)

Soot blowers are aid not involved in the movement and control of fluids but in removing the soot or dust deposited on the heating surfaces (HSs) of the boiler. They are unique to the boilers.

Only a brief description of the important boiler auxiliaries is given in this chapter, covering the salient features such as the process and constructional aspects. Feed pumps are not discussed here because they normally are in the scope of turbine island. However, they are briefly described in Chapters 1 and 2, in Sections 1.8.5 and 2.5.8, respectively.