INTRODUCTION

People throughout much of the world have become dependent upon electricity to operate everything from home lighting systems to the most advanced computers. Without electricity, industrial societies would collapse in short order. A very large part of electric power production comes from steam-driven turbine/generators, and even though other sources of energy are becoming more popular, steam-produced electricity will meet our needs for years to come.

Steam also powers many industrial processes that produce goods and services, including foods, pharmaceuticals, steel, plastics, and chemicals. Yet issues related to global warming, acid rain, conservation of resources, and other economic and environmental concerns require that existing plants be operated with the utmost efficiency, while better energy production technologies are being developed.

This chapter provides information about fundamental boiler designs, many of which are still in use today. Knowledge of these basics provides a stepping-stone for understanding newer steam generation technologies, such as the heat recovery steam generator (HRSG) portion of combined-cycle plants.

The steam generating process can be rather complex, especially when electrical generation is part of the network. Consider Figure 1-1. The boiler produces steam to drive both an industrial process and a power-generating turbine. Condensate recovered from the industrial plant is cleaned, blended with condensed steam from the turbine, and the combined stream flows through a series of feedwater heaters and a deaerator to the boiler. The superheater increases steam heat content, which in turn improves turbine efficiency. The turbine itself is an intricate and finely tuned machine, delicately crafted...