A company's centrifugal air compressor has been in operation for many years. The equipment is installed in a separate factory. The equipment is divided into two layers. The lower layer is two cooling towers. The centrifugal air compressor is installed directly above the cooling tower (upper layer). The air compressor did not make any noise reduction treatment. The control room is on the inner side of the upper building, and the outdoor wall and ceiling are controlled for noise control, but the effect is not satisfactory and the standard is not met. At present, the noise generated by operating equipment has seriously affected the physical and mental health of operators. To this end, the company arranged for a thorough rectification of the noise pollution of the air compressor. 1 Noise characteristics and noise source analysis 1L noise distribution characteristics Field test shows that the unit uses the Dan 2238mediator noise spectrum analyzer to test the noise source distribution under full load conditions. It is 1m away from the machine, the noise is 109.4dB(A), and the noise of the control room is 83.7dB(A), which is much larger than the standard of the industrial enterprise boundary noise not more than 70dB(A) under the requirement of telephone communication. It is expressed in sound insulation. At some point outside the cover, the difference between the sound pressure levels before and after the sound enclosure is added, and the sound insulation amount (also called sound transmission loss) TL can be expressed by the following formula: transmission coefficient. 2.2 Sound insulation cover The sound insulation cover is composed of a metal frame and a sound insulation board, and the metal frame is a moiré pattern of the sound insulation cover manufactured by a wide-band sound absorption structure with a patented technology (patent number ZL30Q520ffl252.2). It can be seen that the color of the moiré pattern gradually changes from cool to warm, the cold color indicates that the value is small, the sound pressure of the outer surface of the sound enclosure is small, and the sound insulation effect is good; the warm color indicates a large value, and the sound pressure of the sound enclosure is better. Large, poor sound insulation. The upper part of the figure is mainly cold color, and the sound insulation cover can meet the noise reduction requirement. The color of the moiré pattern of the side wall gradually changes from cold color to warm color, indicating that the noise of the sound insulation cover gradually becomes larger, and the noise reduction effect is getting worse. . The red area shown by the moiré map needs improvement. The column is made of Q235 steel plate and is manufactured by bending machine. The wide-band combined sound-absorbing structure is installed in the frame. See. A sound absorbing material having a high sound absorption coefficient at a low frequency is added to the sound absorbing structure. The sound absorbing structure adopts a plate structure and horizontal suspension. In order to ensure the stability of the structure, a metal light steel keel is added to the sound absorbing structure to form a frame. The sound insulation of this structure can be used as follows: the areal density of the sound insulating material, kg/cm2; the sound frequency, Hz. The moire of the soundproof cover. 2The improved sound insulation cover is too complicated due to noise reverberation. The wide-band sound absorption structure cannot dissipate more energy. It is necessary to install an improved wide-band sound absorber with sound-blocking plate in the red area. The structure sees that the structure does not reduce the sound absorption performance, and the friction between the materials is damped by the friction inside the damping material, so that a considerable part of the energy is depleted and becomes heat energy, thereby reducing the energy transmission of the noise. In the calculation of the broadband combined sound absorption structure, the arithmetic mean of each frequency band is used to calculate the sound insulation. The sound insulation of the wide-band sound absorption structure is: finite element analysis of the noise reduction effect of the sound insulation cover. The above analysis is an ideal condition. Under the calculation of the sound insulation, the analysis result and the noise reduction requirement only have a margin of 2.98dB(A). Considering the influence of construction and actual noise reverberation, the sound insulation after installing the sound insulation cover may not be possible. To meet the technical requirements, further analysis and improvement of the sound insulation cover is required to make the sound insulation cover perform optimally. 3.1 Finite element analysis Before analyzing the sound insulation performance of the sound insulation cover, firstly use the SYSNOEE software to establish the finite element model of the sound insulation cover. See, by using the moiré diagram to represent the noise reduction effect. Improved design of the sound insulation cover The moiré structure of the improved broadband sound absorption structure is a moiré pattern of the sound insulation cover using improved sound insulation performance. The color of the moiré pattern is mainly cold color, and the sound insulation effect is obviously improved. , indicating that the improvement plan is effective and can be implemented. 4 Noise control implementation observation window processing: In order to facilitate the operation and make the maintenance personnel understand the operation of the equipment, there is an observation window on the side of each door. The observation window uses double-layer sound insulation glass, the thickness of the glass is 5mm, and the glass is 30mm. The air layer is sealed around the glass with a sealing strip. Ventilation and heat treatment: A large amount of heat is generated during the operation of the air compressor, and a forced ventilation and cooling system is required. The hot air flowing through the surface of the device is removed from the exhaust duct installed in the lower layer by a 1.5 kW fan through a composite muffler. Control of the soundproof cover door: In order to facilitate the operator to enter and exit the sound insulation cover for inspection and operation, two independent sound insulation doors are installed, and the improved wide-band sound absorption structure is installed inside the door body. In order to ensure the maintenance of the air compressor and the hoisting of related equipment, the ceiling of the sound insulation cover is detachable, and the wide-band sound absorption structure is sealed. 5 Conclusion After the installation of the sound enclosure, the noise level in the workshop is significantly reduced. According to the on-site assessment by the environmental protection department, the average noise value at 1m away from the compressor enclosure is 83.4dB(A), and the noise of the control room is reduced to 63.5dB. (A), fully meet the requirements of the factory to control the noise of the control room is not more than 65 dB (A). The engineering practice shows that when the sound insulation of the design can not have a large safety margin, the SYSNOISE finite element software can be used to effectively analyze the design effect, and can prompt the design that needs improvement, which provides a basis for effective control of noise. .
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Temperature Rise Class: class H
Ambient Temperature: 40
Overload:10% for 1 hour in every 12 hours
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Insulation: class H
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Special Features:
Brushless Marine Generator
Research on Noise Control of Centrifugal Air Compressor