INTRODUCTION

In order to achieve an acceptable level of performance from the steam turbine, two things are essential:

• individual components comprising the steam path are manufactured in accordance with the design specified requirements

• components are arranged or assembled within the unit so their spatial relationship, relative to the other components with which they will interact, are correct

This compliance with design requirements will optimize the energy conversion process and help ensure the structural reliability of the system is at an optimum level. The spatial requirement within the steam path will be considered in this chapter, along with factors influencing the relative positions of the various components one to the other.

Note: For the purpose of this work the steam path is considered to comprise the stationary and rotating blade rows, their means of attachment, the rotors, and the casings. To complete the arrangement of the components and help ensure a satisfactory design, it is necessary to consider the arrangement made to minimize internal leakage and the leakage occurring from within the casing to other portions of the steam power cycle. In the case of low-pressure sections, leakages into the system must also be considered.

Before considering details and requirements of the individual components comprising the steam path, we must review their positional needs relative to each other, and those factors influencing them when the unit is in operation. Unfortunately, the steam path is available for measurement, adjustment, and gauging only in its cold stationary position conditions under which components must be...