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A '''gas flare''', alternatively known as a '''flare stack''', is an elevated vertical conveyance found accompanying the presence of [[oil well]]s, [[gas well]]s, [[oil rig|rigs]], [[oil refinery|refineries]], [[chemical plant]]s, [[natural gas]] plants, and [[landfill]]s.
A '''gas flare''', alternatively known as a '''flare stack''', is an elevated vertical conveyance found accompanying the presence of [[oil well]]s, [[gas well]]s, [[oil rig|rigs]], [[oil refinery|refineries]], [[chemical plant]]s, [[natural gas]] plants, and [[landfill]]s.


They are used to eliminate waste gas which is otherwise not feasible to use or transport. They also act as safety systems for non-waste gas and is released via [[relief valve|pressure relief valve]] when needed to ease the strain on equipment. They protect gas processing equipment from being overpressured. Also in case of an emergency situation, the flare system helps burn out the total reserve gas.<ref>{{cite book|author=John J McKetta, Editor|title=Encyclopedia of Chemical Processing and Design|publisher=Marcel Dekker|year=1985|isbn=0-8247-2491-7|page=144}}</ref><ref>{{cite book|author=Milton R. Beychok|title=[[Fundamentals of Stack Gas Dispersion]]|edition=Fourth edition|publisher=self-published |year=2005|isbn=0-9644588-0-2}} [http://www.air-dispersion.com air-dispersion.com] See Chapter 11, ''Flare Stack Plume Rise''.</ref><ref>[http://aiche.confex.com/aiche/s06/techprogram/P40539.HTM A Proposed Comprehensive Model for Elevated Flare Flames and Plumes], David Shore, Flaregas Corporation, [[AIChE]] 40th Loss Prevention Symposium, April 2006.</ref>  
They are used to eliminate waste gas which is otherwise not feasible to use or transport. They also act as safety systems for non-waste gas and is released via [[relief valve|pressure relief valve]] when needed to ease the strain on equipment. They protect gas processing equipment from being overpressured. Also in case of an emergency situation, the flare system helps burn out the total reserve gas.<ref>{{cite book|author=John J McKetta, Editor|title=Encyclopedia of Chemical Processing and Design|publisher=Marcel Dekker|year=1985|isbn=0-8247-2491-7|page=144}}</ref><ref>{{cite book|author=Milton R. Beychok|title=[[Fundamentals of Stack Gas Dispersion]]|edition=Fourth ed.|publisher=self-published |year=2005|isbn=0-9644588-0-2}}. See Chapter 11, ''Flare Stack Plume Rise''.</ref><ref>[http://aiche.confex.com/aiche/s06/techprogram/P40539.HTM A Proposed Comprehensive Model for Elevated Flare Flames and Plumes], David Shore, Flaregas Corporation, [[AIChE]] 40th Loss Prevention Symposium, April 2006.</ref>  


However, flaring poses the serious problem of wasting energy uselessly. Flaring basically consists in burning precious resources instead of using them. It also plays a role in the increase of CO<sub>2</sub> emissions.
However, flaring poses the serious problem of wasting energy uselessly. Flaring basically consists in burning precious resources instead of using them. It also plays a role in the increase of CO<sub>2</sub> emissions.

Revision as of 18:11, 1 June 2012

A gas flare, alternatively known as a flare stack, is an elevated vertical conveyance found accompanying the presence of oil wells, gas wells, rigs, refineries, chemical plants, natural gas plants, and landfills.

They are used to eliminate waste gas which is otherwise not feasible to use or transport. They also act as safety systems for non-waste gas and is released via pressure relief valve when needed to ease the strain on equipment. They protect gas processing equipment from being overpressured. Also in case of an emergency situation, the flare system helps burn out the total reserve gas.[1][2][3]

However, flaring poses the serious problem of wasting energy uselessly. Flaring basically consists in burning precious resources instead of using them. It also plays a role in the increase of CO2 emissions.

Function

On oil production rigs, in refineries and chemical plants, its primary purpose is to act as a safety device to protect vessels or pipes from over-pressuring due to unplanned upsets. Pressure control valves are set at predetermined pressures to release excess gas, thus allowing continued operation during upset conditions. Whenever plant equipment items are over-pressured, the pressure relief valves on the equipment automatically release gases (and sometimes liquids as well) which are routed through piping runs called flare headers to the flare stacks. The gases and/or liquids are separated in a flare knock out drum with the gas piped to the flare stacks for burning or for lighter gases venting. The size and brightness of the resulting flame depends upon how much flammable material was released. Typically there may be more than one flare system handling high pressure gas, low pressure gas, sour or corrosive gas, cold gas and wet gas. Vents (unignited flares) are used typically on gas plants for emergency gas disposal and are designed to operate in an emergency at sonic velocity. Flare gas recovery systems are occasionally used to collect low flows of waste gas and return it to the Process Plant as opposed to burning the gas. Steam can be injected into the flame to reduce the formation of black smoke. The injected steam does however make the burning of gas sound louder, which can cause complaints from nearby residents. Compared to the emission of black smoke, it can be seen as a valid trade off. In order to keep the flare system functional, a small amount of purge gas flows continuously, whilst there are continuously burning pilots, so that the system is always ready for its primary purpose of burning as an over-pressure safety system. Enclosed ground flares are engineered to eliminate toxic and corrosive components, reduce smoke, and contain the flame within the enclosure. Burn pits are used to dispose of waste hydrocarbon liquids and are increasingly being designed out due to their unacceptable dirty appearance.

Climatic effects

Flaring and venting of natural gas from oil and gas wells contribution to greenhouse gases has declined by three-quarters in absolute terms since a peak in the 1970s of approximately 110 million metric tons/year of CO2 and now accounts for 0.5% of all anthropogenic carbon dioxide emissions.[4]

Recently, under the Kyoto Protocol, garbage collecting companies in some developing nations have received a carbon bonus for installing combustion devices for the methane gas produced at their landfills, preventing methane from reaching the atmosphere. When burned, the methane is converted to heat, water and CO2. (According to the IPCC Third Assessment Report report of the IPCC, Methane is 23 times more powerful a greenhouse gas than CO2)

Volume

The World Bank estimates that over 134 billion cubic metres of natural gas are flared or vented annually, an amount equivalent to more than 20 percent of the United States’ gas consumption or 33 percent of the European Union’s gas consumption per year.[5]

This flaring is highly concentrated: 10 countries account for 70% of emissions, and twenty for 85%. The top ten leading contributors to world gas flaring in 2010, were (in declining order): Russia (26%), Nigeria (11%), Iran (8%), Iraq (7%), Algeria (4%), Angola (3%), Kazakhstan (3%), Libya (3%), Saudi Arabia (3%) and Venezuela (2%).[6]

Russian flaring

Russia has announced it will stop the practice of gas flaring as stated by deputy prime minister Sergei Ivanov on Wednesday September 19, 2007.[7] This step was, at least in part, a response to a recent report by the National Oceanic and Atmospheric Administration (NOAA) that concluded Russia's previous numbers may have been underestimated. The report, which used night time light pollution satellite imagery to estimate flaring, put the estimate for Russia at 50 billion cubic meters while the official numbers are 15 or 20 billion cubic meters. The number for Nigeria is 23 billion cubic meters.[8]

See also

References

  1. John J McKetta, Editor (1985). Encyclopedia of Chemical Processing and Design. Marcel Dekker. ISBN 0-8247-2491-7. 
  2. Milton R. Beychok (2005). Fundamentals of Stack Gas Dispersion, Fourth ed.. self-published. ISBN 0-9644588-0-2. . See Chapter 11, Flare Stack Plume Rise.
  3. A Proposed Comprehensive Model for Elevated Flare Flames and Plumes, David Shore, Flaregas Corporation, AIChE 40th Loss Prevention Symposium, April 2006.
  4. 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.Template:Dead link
  5. The World Bank, World Bank, GGFR Partners Unlock Value of Wasted Gas", World Bank 14 December 2009. Retrieved 17 March 2010.
  6. Global Gas Flaring reduction, The World Bank, "Estimated Flared Volumes from Satellite Data, 2006-2010."
  7. News.yahoo.com
  8. The Boston Globe: Russia top offender in gas-flare emissions.

External links