Power generating plants, like other manufacturing plants, process raw materials into useful products, often accompanied by some waste products. For power plants the useful product is electrical energy. The waste products for fossil plants include ash and smoke visibly and heat invisibly.
Similarities include the use of equipment and materials that serve to expedite and improve efficiency of operations, although they may not be directly involved in the manufacture of the product. For example, water may be used to produce the steam and for cooling purposes, oil to lubricate moving parts, and fans and pumps to move gases and fluids.
Additional similarities include facilities for the reception of raw materials, disposal of waste, and for delivery of the finished product as well as trained personnel to operate the plant. Economic considerations, including capital investment and operating expenses which determine the unit costs of the product while meeting competition (oil, natural gas in this case) are common to most business enterprises.
There are some important dissimilarities. As a product electricity not only is invisible and hazardous in its handling but for the most part cannot be stored. Inventories cannot be accumulated and the ever changing customer demands must be met instantly.
All of this imposes greater standards of reliability in furnishing a continuing supply both in quantity and quality. This criteria assumes even greater importance as such generating plants are vital to national economy and contribute greatly to the standard of living.
In the larger central generating plants, fossil or nuclear energy (in the form of fuel) is fi rst converted into heat energy (in the form of steam), then into mechanical energy (in an engine or turbine), and fi nally
into electrical energy (in a generator) to be utilized by consumers. A
schematic arrangement is shown in Figure 2-1, below.
Most commonly, electricity is produced by burning a fossil fuel (coal, oil or natural gas) in the furnace of a steam boiler. Steam from the boiler drives a steam engine or turbine connected by a drive shaft to an electrical generator.
A nuclear power plant is a steam-electric plant in which a nuclear reactor takes the place of a furnace and the heat comes from the reaction within the nuclear fuel (called fi ssion) rather than from the burning of fossil fuel.
The equipment used to convert heat to power is essentially the same an ordinary steam-electric plant. The product, electrical energy is identical; see Figure 2-2.
The processes and the equipment to achieve these energy transformations will be described in fundamental terms, encompassing arrangements and modifi cations to meet specifi c conditions. Some may be recognized as belonging to older practices (for example burning lump coal on iron grates).
While serving purposes of illustration, it must be borne in mind that for a variety of reasons, some of the equipment and procedures continue in service and, hence, knowledge of their operation is still desirable.
Pertinent changes, developments and improvements, brought about by technological, economic and social considerations are included.
The four conversion processes in a typical steam generating plant may be conveniently separated into two physical entities, following accepted general practice. The fi rst two processes comprise operations known as the BOILER ROOM, while the latter two are included in those known as the TURBINE ROOM.
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