Sand used in a brick and tile manufacturing facility was being oxidised in a 'sandburner'. This consists of a four-foot diameter, twenty-four foot long rotating drum. At one end is the burner unit running on butane gas which generated a flame down the centre of the drum. Noise levels were up to 95dB throughout most of the sandburner building. The area was very hot and dusty.
Combustion noise in furnaces and burners is sensitive to fluctuations in the flow and mixing of air and fuel. A variety of techniques are available to control flame-front turbulence and hence the noise that is generated. This can be particularly valuable where low frequency noise dominates making conventional solutions very costly.
The noise in the typical operator work area was reduced by 9dB. The octave band spectrum before and after modification is shown below (Note: Both measurements were made under similar conditions (900°C) but with a higher gas flow rate for the modified measurement (29 ft3/min compared with 23 ft3/min) which masks the noise reduction slightly).
£500 (the material costs were negligible, the majority of costs were for fabrication and fitting of the flow control sleeve).
Redland Roof Tiles Ltd. (now Lafarge Roofing Ltd.) & Industrial Noise and Vibration Centre Ltd.