Boilers and Process Heaters: virtual tour

Type Units

Main : 1 : 2 : 3

Boilers are combustion devices used to produce steam or heat water. Steam is produced in boilers by heating water until it vaporizes. The steam is then channeled to applications within a facility or group of facilities via pipes. Steam is an important power and heating source for the U.S. economy. It is used in the preparation or manufacturing of many key products, such as paper, petroleum products, furniture, and chemicals. Steam is also used to heat buildings and to generate the majority of the electricity consumed in this country. There are literally thousands of boilers currently being used in the United States throughout a wide variety of industries.

A boiler system includes the boiler itself, associated piping and valves, operation and safety controls, water treatment system, and peripheral equipment such as pollution control devices, economizers, or superheaters. Most boilers are made of steel, cast iron, or copper. The primary fuels used by boilers are coal, oil, and natural gas, but some use electricity, waste gases, or biomass.

The heat transfer configuration of a boiler refers to the method by which heat is transferred to the water. The four primary boiler configurations are watertube, firetube, cast iron, and tubeless. Most industrial users tend to rely on either watertube or firetube configurations.  There are five major design types for fossil fuel industrial boilers that will be covered by the boiler MACT:

• Stoker-Fired Boilers (Coal)
• Pulverized Coal Boilers (Coal)
• Fluidized Bed Combustion (FBC) Boilers (Coal)
• Tangentially Fired Boilers (Coal, Oil, Natural Gas)
• Wall-fired Boilers (Coal, Oil, Natural Gas)

Process heaters are primarily used as heat transfer units in which heat from fuel combustion is transferred to process fluids, although they may also be used to transfer heat to other nonfluid materials or to heat transfer materials for use in a process unit (not including generation of steam). Process heaters are generally used in heat transfer applications where boilers are inadequate. Often these are uses in which heat must be transferred at temperatures in excess of 90° to 204°C (200° to 400°F). Process heaters are used in the petroleum refining and petrochemical industries, with minor applications in the asphalt concrete, gypsum, iron and steel, and wood and forest products industries.

The universe of process heaters is divided into two categories:

Indirect-fired process heater—any process heater in which the combustion gases do not mix with or exhaust to the atmosphere from the same stack(s) or vent(s) with any gases emanating from the process or material being processed.

Direct-fired process heater—any process heater in which the combustion gases mix with and exhaust to the atmosphere from the same stack(s) or vent(s) with gases originating from the process or material being processed.

Main : 1 : 2 : 3