User:Milton Beychok/Sandbox
A flare stack or gas flare is an elevated vertical vent pipe used in petroleum refineries, chemical plants and petrochemical plants, oil and gas drilling sites, natural gas processing plants, and landfills used for burning off unusable waste gas or flammable gas and liquids released by pressure relief valves during unplanned over-pressuring of plant equipment.[1][2][3]
The purpose of flare stacks
In petroleum refineries, chemical plants and petrochemical plants, oil and gas drilling sites,and natural gas processing plants, the main purpose of a flare stack is that of safety by protecting pressure vessels or pipes from over-pressuring due to unplanned upsets.
In landfills, the primary purpose of this device is to vent and/or burn waste gas which results from the decomposition of materials in the landfill.
How flare stacks work
Whenever plant equipment items are over-pressured, the pressure relief valves provided as essential safety devices on the equipment automatically releases gases (and sometimes liquids as well) which are routed through large piping runs called flare headers to the flare stacks. The released gases and/or liquids are burned as they exit the flare stacks. The size and brightness of the resulting flame depends upon how much flammable material was released.
Steam is very often injected into the flame to reduce the formation of black smoke. In order to keep the flare system functional, a small amount of gas is continuously burned, like a pilot light, so that the system is always ready for its primary purpose as an over-pressure safety system.
Environmental impacts
The flaring and venting of assocated gas from oil drilling sites is a significant source of carbon dioxide (CO2) emissions. The amount of such emissions has declined by about 75% since a reaching peak in the 1970s and now accounts for about 1/2 of one percent of all anthropogenic carbon dioxide emissions.[4]
The World Bank estimates that 100 billion cubic meters of raw natural gas are flared or vented annually. This flaring is highly concentrated: 10 countries account for 75% of emissions, and twenty for 90%.[5] The largest flaring operations occur in the Niger Delta region of Nigeria. The leading contributors to gas flaring are (in declining order): Nigeria, Russia, Iran, Algeria, Mexico, Venezuela, Indonesia, and the United States.[6]
References
- ↑ John J McKetta, Editor (1985). Encyclopedia of Chemical Processing and Design. Marcel Dekker, 144. ISBN 0-8247-2491-7.
- ↑ Milton R. Beychok (2005). Fundamentals of Stack Gas Dispersion, Fourth edition. self-published. ISBN 0-9644588-0-2. www.air-dispersion.com See Chapter 11, Flare Stack Plume Rise.
- ↑ A Proposed Comprehensive Model for Elevated Flare Flames and Plumes, David Shore, Flaregas Corporation, AIChE 40th Loss Prevention Symposium, April 2006.
- ↑ Global, Regional, and National CO2 Emissions. In Trends: A Compendium of Data on Global Change, Marland, G., T.A. Boden, and R. J. Andres, 2005, Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee.
- ↑ The World Bank, Global Gas Flaring Reduction"
- ↑ The Climate Law Organization, Friends of the Earth International.