Gas pipelines require large compressors to force gas through the pipelines. These compressors may have a fan width of 7 to 12 feet, and move between 96,000 cubic feet of air per minute and 198,000 cubic feet of air per minute. These compressors and their cooling fans generate significant noise, such that they may create a nuisance for those nearby. For this reason, attempts have been made to make the compressors as quiet as possible, such as by modifying the shapes of the cooling fan blades. However, there are many compressors in existence that are not quiet and that continue to create a nuisance. While the compressors are usually located in isolated areas, continued expansion of residences and decreasing tolerance for environmental noise have created a conflict between existing compressors and people living near them.
It has therefore become desirable to reduce the noise emitted by compressors, and particularly their cooling fans, and it is therefore an object of the present invention to reduce the noise emitted by large compressors.
Noise reduction in large compressors is not an easy task particularly when it is desired to reduce the noise emitted by the air intake of the cooling fan of a compressor. The reason for this is that conventional silencers (as for example used on motor vehicles) create a considerable pressure drop that is unacceptable across the air intake of the cooling fan. With a large pressure drop, air supply is reduced which may result in over heating of the gas being conveyed in the pipeline or of the compressor itself, especially on a hot day (&gt;90.degree. F.). It is therefore a further object of this invention to provide a noise reduction unit for a cooling fan of a compressor unit that allows relatively free flow of air into the cooling fan of the compressor unit.
Thus in one embodiment of the invention, there is provided a sound reduction unit for a compressor, in which the compressor has a cooling fan and an air intake, and the sound reduction unit includes a housing forming an enclosure about the air inlet and a plurality of sound absorbing baffles disposed in the housing and blocking any direct passage of air into the air inlet. The baffles provide free flow of air, which may be achieved by staggering the baffles in overlapping angular rows in a generally rectangular housing, but which preferably includes allowing a gap between the noise reduction unit and the cooling fan of the compressor, with a flange baffle extending from the noise reduction unit beyond the cooling fan.