Noise Test of Centrifugal Air Compressor in Catalytic Workshop of Chemical Machinery Refinery Wang Jia* Hao Point Yuan Jinning (School of Chemical Engineering, China University of Petroleum) Sound Test. The main noise sources and their characteristics are identified by spectrum analysis. The noise level A is measured by the sound level meter, and the noise propagation law is obtained. The noise level is evaluated according to the noise standard of the industrial enterprise boundary, and the noise control measures are proposed. The working state of each component of the compressor is reflected in the noise through a certain transmission path. The noise signal is tested and analyzed, and the main noise source of the compressor can be effectively detected. The noise source is a comprehensive noise source M. The frequency is wide, showing medium-low frequency characteristics, and the propagation distance is far. The sound level is generally above 80dB, which is high noise. Its existence seriously affects the lives of the surrounding residents and causes a certain degree of harm to the physical and mental health of the operators. H. The author used a sound level meter and a two-channel data collector to perform sound level on a centrifugal air compressor in a refinery catalytic plant. Testing and spectrum testing. Through spectrum analysis, the main noise sources and their characteristics are found out. Through the sound level test, the law of noise propagation is obtained. 1 Noise test 1.1 Test instrument TES1350A sound level meter is generally placed in the axial and horizontal direction of the pump. The position of the measuring point may be different for different pump; PL302 dual channel data collector / spectrum analyzer is available As a data collector, the device is inspected (amplitude, spectrum), and can be used as a spectrum analyzer to perform various analysis on the device (time domain waveform, spectrum, three-dimensional spectrum, power spectrum, envelope spectrum), which is due to the double The channel can be operated while performing the analysis of the axis trajectory and related functions, coherence functions, and transfer functions. 1.2 Test plan and object noise test The position of the test point () can be determined according to the size of the centrifuge air compressor room. *Wang Jia, female, born in September 1986, graduate student. Dongying City, Shandong Province, 257061. Chemical machinery measuring point 8 today ~ 2 noise spectrum. 1.1 Noise Analysis of Centrifugal Air Compressor The noise of a compressor can be divided into two types: self-noise and interference noise. The noise is related to the sound produced by the flow of fluid (air) through the blades, which is related to the reaction of the blades to the disturbances, which move in the same system as themselves. There may be several reasons for both self-noise and interference noise, depending on the type of rotating part. The self-noise and interference noise of the centrifugal air compressor are as follows: a. The discrete pure tone component of the blade passing frequency and its harmonics; the number of blades revolutions; the number of blades; the calculation result of equation (2) can be seen that the first The peak frequency is approximately equal to the compressor blade passing frequency, and the other two peak frequencies are in integral multiples with the first peak frequency, indicating that the two peak frequencies are the high-order harmonic frequencies of the blade passing frequencies, respectively. It can be concluded that the main sound source of the discrete noise of the centrifugal air compressor is the pressure pulsation generated when the blade passes through a certain point in the space. It produces a discrete pure tone family with the blade pass frequency as the fundamental frequency. 3. 2.1.2 Three-phase asynchronous motor noise analysis The noise of the motor is generally composed of aerodynamic noise, mechanical noise and electromagnetic noise. The aerodynamic noise is mainly caused by the motor cooling fan. The noise size, frequency and characteristics are determined by the shape, size, number and number of revolutions of the fan blades. The mechanical noise is caused by bearing friction, imbalance of the machine's operation and structural resonance. The mechanical noise of the bearings with poor lubrication, the motor with large eccentricity and the resonance mechanism is the most prominent H; the electromagnetic noise is caused by the alternating electromagnetic attraction and magnetostriction between the stator and the rotor, and its size and The motor power and the number of poles are related, and the electromagnetic noise of the high-power motor accounts for a considerable proportion. Since the power of the motor is quite large and the number of fans cannot be determined, when analyzing the electromagnetic noise, the frequency of the electromagnetic noise can be calculated as follows: R - the number of rotor slots; the number of p poles; the speed of the magnetic field and the rotor speed The unit slip between the two (actually the typical value is 0.02. The R comparison of the motor model shows that the above calculation results and the position of the chemical machine in the middle of the figure are the closest distance from the wall to the wall, which is affected by the reflection and refraction of the wall. Big. 3 Control measures The noise of the workshop is basically above 80dB, which exceeds the allowable range of industrial enterprise boundary noise standard (GB1234840). Therefore, it is recommended to adopt the following measures to control noise: a. Improve blade structure and reduce discrete noise; b. Adopt appropriate Add air gap, strict inspection and improve assembly process to reduce electromagnetic noise 63; c. Use sound insulation, sound prevention and sound absorption equipment in the workplace to reduce the impact of noise on operators and surrounding residents. 4 Conclusions 4.1 Through the analysis of the noise spectrogram, the main noise sources of the workshop include the aerodynamic noise caused by the pressure pulsation of the air passing through the space of the centrifugal air compressor at a certain point in the space and the electromagnetic noise of the motor. 4.2 Through the noise level analysis, the noise propagation law of the workshop is basically the same as the noise propagation law of the free field and the semi-free field. Both of them are the trend of the sound level decreasing with the increase of the distance, and the rise of the curve is due to the measuring point. It is too close to the walls around the workshop and is caused by the reflection and refraction of the walls.
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