Smokestack

A smokestack, also called a chimney, is a tall vertical structure designed to vent exhaust gases from industrial processes, boilers, or power plants into the atmosphere. It serves to remove heat, smoke, and pollutant-laden gases from the building or facility, improve draft for combustion, and reduce ground-level concentrations near equipment. The stack typically connects to a flue or duct from a furnace, boiler, or engine room and is built to withstand high temperatures and corrosive gases. They vary in height and diameter, often reaching several tens of meters for large facilities, to promote dilution and dispersion of emissions.

Construction and design concerns common materials include brick, reinforced concrete, or steel. Stacks may be single or multi-flue, with a base, a vertical shaft, and sometimes a weather cap or discharge hood. Interiors are lined to resist heat and corrosion, and many stacks include dampers for controlling exhaust flow and insulation to reduce heat loss. Foundations must resist wind loads, thermal expansion, and seismic forces.

Environmental aspects: modern smokestacks may house pollution-control equipment such as scrubbers, electrostatic precipitators, or fabric filters to reduce particulates, sulfur oxides, and other pollutants before release. In practice, the height and siting of a stack are guided by air-quality regulations and dispersion models to minimize ground-level impacts.

Cultural and historical context: smokestacks are prominent elements of industrial heritage, often surviving as monuments or repurposed in adaptive reuse projects. Some may be preserved as landmarks; others are dismantled when facilities are decommissioned.

In transportation, the term smokestack can also refer to the funnel on steam locomotives and steamships, though modern vessels use the term funnel or stack.