Flue-Gas Stack

A flue gas stack, also called a smoke stack or chimney stack, is a vertical pipe, channel or similar structure that exhausts combustion gases from furnaces, boilers and power plant equipment to the outside air. The exhausted gases typically carry carbon dioxide, water vapor, nitrogen and oxygen along with pollutants such as particulate matter, carbon monoxide, nitrogen oxides and sulfur oxides. In power plants, a stack uses the natural tendency of hot gas to rise, called the stack effect, to draw combustion air into the boiler while expelling exhaust, and some stacks reach heights of up to four hundred twenty meters specifically to strengthen this effect and disperse pollutants more widely; modern facilities often add fans and pollution control equipment alongside the stack to meet environmental regulations.