In this chapter we have seen how a `master demand' signal is generated with respect to the nature of the duties that the plant is designed to undertake. This signal is responsible for ensuring that the boiler reacts to changes in demand, and it must also coordinate the operation of each of the subsidiary systems. The main areas involved in this process are the combustion and draught systems in conventional boilers, the feedwater and the steam temperature control systems in both conventional boilers and HRSGs.

Chapter Contents:

• 4.1 Nature of the demand
• 4.2 Setting the demand in power station applications
• 4.2.1 Operation of the UK electricity trading system
• 4.2.2 Frequency response services
• 4.3 The master demand in a power station application
• 4.3.1 Boiler-following operation
• 4.3.2 Turbine-following operation
• 4.3.3 Coordinated unit control
• 4.3.4 Relative performance
• 4.3.4.1 Response of the boiler-following system
• 4.3.4.2 Response of the turbine-following system
• 4.4 Load demand in CHP plants
• 4.5 WTE plants
• 4.6 Heat recovery steam generators
• 4.7 Summary

Inspec keywords: steam power stations; boilers; combustion

Other keywords: steam generator; feedwater; subsidiary systems; HRSGs; steam temperature control systems; draught systems; combustion systems; conventional boilers; master demand signal

Subjects: Steam power stations and plants