The Study Of The Prediction Of Noise Impact And Technology Of Noise Control In The Liquefied Air Station

Air is a mixed gas composed of multiple components.It is equimolar and isotonic.It extracts heat from the air and cools it until it reaches the condensing temperature and begins to liquefy.Thus,different components of nitrogen,oxygen,carbon dioxide,etc.The gases are separated one by one.Liquefied air stations require air filtration equipment,air compression and expansion equipment,auxiliary cooling devices,etc.during these processes.With the rapid development of China's industry,the demand for high-purity air products has been rising.As a result,liquefied air stations have spread widely in various developed cities in China in recent years.This article introduces the concept of liquefied air stations,analyzes the types and characteristics of noise sources in large liquefied air stations,and makes noise effects on noise sources such as representative cooling towers,self-cleaning air filters and air separation plants in liquefied air stations.Forecasting,according to the experimental results of sound source noise control tests,the sensitivity of sensitive air in the liquefaction air plant site has reached the “Acoustic Environmental Quality Standard”(GB3096-2008)and the“Emission Boundary Noise Standard of Industrial Enterprises(GB12348-2008)”.The requirements of the 3 categories in the standard.The main content and conclusions are as follows:(1)Analyze and study the treatment methods of major noise sources in liquefied air stations at home and abroad.It is known that the cause of noise in the forced wet mechanical cooling tower is caused by the following factors: intake and exhaust of the fan,flooding of the filler,pump operation of the cooling tower,and operation of the motor.The noise is mainly composed of aerodynamic noise,and the frequency band exhibits medium and low frequency characteristics.Air filter noise mainly consists of aerodynamic noise,fan-shell vibration-related solid-state noise,and frequency bands with low-middle-frequency noise,especially low frequency noise control is a difficult problem.The main sources of air compressor noise are the intake and exhaust noise,“surge” and “liquid strike” of the wind turbine.Its low-frequency noise has strong penetrating power and is a difficult point for control.In this paper,through field measurement and analysis,the noise of 1m near the inlet of the cooling tower is 79.7 dB(A),85.1 dB(A),and the diffuser noise of the self-cleaning air filter is 84.5 dB(A).After analyzing the noise frequency spectrum,the main characteristics of the two typesof noise are mid-low frequency noise,and the noise source noise impact prediction and control test study.(2)This study selects the self-cleaning air filtration system,cooling system,and air compressor factory noise source located in the liquefied air stations in the Category 3acoustic environment functional area as the research object,and uses the“Environmental Impact Assessment Technical Guidelines Acoustic Environment”(HJ2).The prediction model of noise attenuation in.4-2009)and the surface acoustic source prediction model using the energy superposition method,according to the type,characteristics and location of the noise source,select different prediction models for prediction,using the dormitory building at 5m away from the liquefied air station site.Sensitive points,predict the noise level of each sound source,and the superimposed noise effect of vertical distance attenuation.The results show that the error between the predicted value and the measured value obtained by using the environmental assessment guideline and the energy superposition method in the noise attenuation prediction of the inlet face of the cooling tower unit is in the range of 2.6 dB(A)and 1.3 dB(A),respectively.The predicted value of noise attenuation predicted by the inlet of the cooling tower unit as a surface acoustic source and using the energy superposition method is more in line with the actual situation.According to the prediction,the noise reduction required by the cooling tower unit and the self-cleaning air filtration system is16.5 dB(A),2.3 dB(A).(3)Noise reduction tests of the self-cleaning air filter and the cooling tower unit were conducted based on the prediction results.The self-cleaning air filter was installed with an integrated suction sound enclosure,an impedance composite muffler at the air inlet,and a noise reduction test.After the completion of the self-cleaning air filter air intake noise reduction 16.1 dB(A),the wind speed before and after the test increased0.2 m / s,increased resistance loss of 7.02 Pa,wind speed and resistance loss control within a reasonable range;test in the cooling tower Impedance composite muffler is installed at the air inlet and outlet.After the test is completed,the noise of the cooling tower unit is reduced by 22.1dB(A),which meets the noise reduction required for prediction.The noise at each measuring point of the floor meets the “Acoustic Environmental Quality Standard”(GB3096-2008).Category 3 noise limits.(4)The noise and vibration of the air separation plant in the liquefied air station have a great influence on the noise at the plant boundary.This study selected liquefied air stations in three types of districts as the research object,using the method ofenvironmental sounding equivalent to the sound power level of indoor sound sources in the EIA guidelines to predict noise impact on the noise on the floor next to the noise in the engine room.The analysis and analysis show that the noise in the first floor is mainly affected by the air sound and the solid-state sound.The excessive noise levels of the 2nd and 3rd floors are caused by the solid-borne sound caused by the vibration of the equipment in the equipment room.(5)Based on the analysis results,the vibration isolation and noise reduction tests of the air separation room were conducted.The test was conducted using a composite vibration isolation structure combining a concrete base,a spring shock absorber,and a rubber vibration damping pad to perform vibration isolation on the air compressor unit.Compression host installed double rubber cushion,hanging sound absorbers in the room and replace the sound insulation door,sound insulation window,after the completion of the test,the noise within the first floor of the office building from 65.1dB(A)to 48.6dB(A)The noise levels of all floors have met the requirements of the Class 3 areas in Table2 and Table 3 of the "Standard for the Discharge of Noise from Social Living Environment"(GB22337-2008).