ABSTRACT
Steam generators, or boilers as they are often called, form an essential part of any
power plant or cogeneration system. The steam-based Rankine cycle has been
synonymous with power generation for centuries. Though steam parameters such
as pressure and temperature have been steadily increasing during the last several
decades, the function of the boiler remains the same, namely, to generate steam at
the desired conditions efficiently and with low operating costs. Low pressure
steam is used in cogeneration plants for heating or process applications, and high
pressure superheated steam is used for generating power via steam turbines.
Steam is used in a variety of ways in process industries, so boilers form an
important part of the plant utilities. In addition to efficiency and operating costs,
another factor that has introduced several changes in the design of boilers and
associated systems is the stringent emission regulations in various parts of the
world. As discussed in Chapter 5, the limits on emissions of NOx;CO; SOx, and particulates have impacted the design and features of steam generators and steam
plants, not to mention their costs. Today’s cogeneration systems and power plants
resemble chemical plants with NOx; SOx, and particulate control systems forming a major portion of the plant equipment. Oil-and gas-fired packaged
boilers used in cogeneration and combined cycle plants have also undergone
significant changes during the last few decades. Selective catalytic reduction
systems (SCRs) are used even in packaged boilers for NOx control, adding to
their complexity and costs.
