Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
  • G01M3/00—Investigating fluid-tightness of structures
  • G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
  • G01M3/04—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point

Definitions

• the present invention relates to a method of detecting the presence and location of a gas leak, such as a leak of natural gas.
• Gas leak detection is an important safety issue to most oil and gas industries.
• In the United Kingdom there is a network of over 0.25 million kilometres of pipe. Gas leaks present a hazard across the entire gas chain, from offshore gas and oil exploration and production, through to the processing, transmission, storage and distribution of gas onshore, to its utilisation by industrial and domestic customers.
• Many thousands of engineers are engaged in the United Kingdom in day-to-day gas detection activities in response to typically half a million public reported escapes per year.
• a method of detecting the presence and location of a gas leak, the leaking gas comprising a critical component including the following steps:-
• step (iii) repeating step (i) about the second reference point.
• the present invention is based upon the discovery that gas at the edges of an expanding plume can be detected by avoiding such mixing and averaging effects and by progressively moving in the suspect direction.
• the critical component will generally be methane where, for example, the leaking gas is natural gas.
• the invention is however not limited to the detection of fuel gas such as natural gas. When other gas detectors are used, the invention can find broad applications in chemical refineries and storage plants and for environmental pollution monitoring purposes.
• the threshold lies above an average background value for the critical component. For example, in the case of methane, a typical average background level is 1.7 ppm, the threshold for the method according to the invention can be set at, for example 10 ppm.
• the sensor may be exposed to the atmosphere in a plurality of different directions about a reference point by sweeping the sensor around the reference point and continuously monitoring the output thereof.
• the sensor is preferably selected from naked flame ionisation based devices and open path optical devices.
• Optical sensors inherently have very fast response times as they are not subject to, for example, thermal response delays found in many sensors.
• An optical sensor with scratch resistant (e.g. sapphire) windows is a sufficiently robust device, and apart from occasional surface cleaning will withstand normal gas detection duties, being generally less affected by water than other sensor devices.
• the optical device may have an open path of at least 0.5m, typically from 0.5 to lm, for example 0.5m. This is especially convenient where the device is to be hand held.
• Flame ionisation sensors are also inherently fast, again because of the lack of thermal mass in the system.
• the wind direction at the first reference point is measured and the selection of the second reference point takes account of the measured wind direction.
• Service gas pipes tend to be of small diameter, and therefore, where the route of the pipe is already known, then walking the pipe with a wide open path detector will lead to more rapid identification of the leak site.
• the pipeline layout information is provided as data in the form of a computerised map held in a computing means, the point at which gas is detected and the upwind direction at that point can be entered into the computing means, for example, by entering appropriate co-ordinates.
• the computing means can then determine the intersection of one or more pipelines with the wind direction from the point at which gas was detected to provide the most likely gas leak source location.

Landscapes

• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Examining Or Testing Airtightness (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=9919310

Family Applications (1)

Country Status (4)

Families Citing this family (2)

Family Cites Families (10)

• 2001
  • 2001-07-27 GB GB0118340A patent/GB0118340D0/en not_active Ceased
• 2002
  • 2002-07-26 WO PCT/GB2002/003437 patent/WO2003012387A2/en not_active Ceased
  • 2002-07-26 EP EP02749068A patent/EP1415136A2/de not_active Withdrawn
  • 2002-07-26 GB GB0217277A patent/GB2382656B/en not_active Expired - Fee Related
  • 2002-07-26 JP JP2003517532A patent/JP2004537718A/ja active Pending

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events