The sources of noise in domestic, aerated, natural gas burners are located and discussed.
Injector noise, resonances within the body of the burner, and flame roar are the components of the overall noise, each playing a dominant role in a given frequency range. Techniques for reducing the noise level are developed and their practical application described.
THE NOISE OF NATURAL GAS BURNERS
The discovery of large recoverable reserves of natural gas under the North Sea has transformed the supply position and market prospects of the British gas industry. Present policy is to introduce North Sea gas rapidly in order to obtain the advantages of this low cost primary, indigenous fuel. 1 However, in the domestic field, the use of natural gas, which consists of over 90% methane with low flame speed, has necessitated the replacement of silent non-aerated (neat gas) burners with noisier aerated burners. Figure 1 shows typical aerated burners--the Bray universal burner, so called because it is suitable for both town and natural gas, and the Bray flared head jet which is used mainly to convert domestic boilers.
Essentially, an aerated burner is a type of Bunsen burner. An injector sends a jet of gas into a mixing tube and entrains primary air. The flame burns on a suitable port, or ports, and secondary air diffuses into the flame, completing the combustion process.
* On secondment to Chelsea College from the South Eastern Gas Board.