Industrial noise is the main source of noise pollution. The impact and harm of noise on the human body can be divided into two aspects. On the one hand, it means harming people's health and causing various diseases; on the other hand, it means disturbing the environment and affecting people's normal. work and life. The main harms of noise to human health are: damage hearing, causing noise deafness; causing cerebral cortex excitation and balance disorders, cerebral vascular dysfunction, leading to neurasthenia; damage to the cardiovascular system, triggering digestive disorders, affecting endocrine. Noise interferes with people's normal life, rest, language conversations and daily work and study, distracting and reducing work efficiency. High-intensity noise can also cause damage to building structures and buildings.
The fundamental way to control noise pollution is to reduce the noise of the machine itself. At the same time, various methods such as sound absorption, noise reduction, sound insulation, vibration isolation and damping can be used to prevent noise pollution.
1 Overview A smelter oxygen station is equipped with 2 sets of air turbine compressors manufactured by Shenyang Blower Factory. The speed is 12 000 r / min, the medium is air, and the air volume is 32 000 m 3 / h. The turbine air pressure When the machine is running, it generates up to 106 decibels of harsh noise, which directly harms the physical and mental health of the employees in the operation position. To this end, in 2003, the company as a hidden danger control project to control the noise reduction of the air compressor compressor of the oxygen station, and achieved good results.
2 Noise source investigation and analysis 2 1 Machine room layout and its impact Oxygen station Turbine air compressor room is a two-storey brick-concrete structure factory with a total construction area of ​​about 2 000 m 2 , of which the machine room area is about 1 800 m 2, on duty. Room, office, etc. 200 m 2 . The oxygen station is located in the southeast-facing edge of the smelting production area, and is far enough away from the residential area to affect the living environment. However, the area within the workshop and adjacent places are subject to different levels of acoustic pollution.
Two turbine air compressors on the second floor of the machine room are installed on the east side of the plant. Two oxygen compressors are installed on the west side of the plant. The control instruments are placed in the duty room. Two turbine air compressors and two oxygen compressors are used. The simple sound insulation screen is enclosed (no roof), the office and the engine room are connected to each other. The duty room and the computer room are separated by building. All the lighting and windows in the computer room are not treated with sound insulation. The first floor of the machine room is mainly 2 turbine air compressors. And the water cooler part of 2 oxygen compressors, as well as other pump equipment and process piping. Due to the installation requirements of the equipment and related roads, the first and second floors are partially connected to each other, so noise is also transmitted through these channels. In addition to the instrument monitoring in the duty room, the equipment room operators must often enter the equipment room for inspections and are completely exposed to high noise. According to the survey, operators who have been working in this position for more than three years have different degrees of hearing loss.
2 2 Noise source monitoring and analysis The results of on-site monitoring of air compressor system noise are as follows: 1 2nd floor of the engine room 2 sets of turbine air compressors, 1 m outside the sound insulation board, each measuring point A sound level is 93 7 96 4 dB, the air compressor in the sound insulation enclosure is 106 7 dB(A), and the spectrum analysis of the measuring points in the air compressor enclosure shows that the noise characteristics of the turbine air compressor have obvious broadband characteristics, that is, from The noise value of 500 8 000 Hz exceeds the evaluation value of N85, with a peak of 2 000 Hz of 96 dB(A) and 104 dB(A).
2 The two oxygen compressors installed on the second floor of the second floor are also treated with sound-insulating coamings. The sound level of each measuring point A is 91 3 94 5 dB from the outside of the wall, and the noise value of the measuring point at the west end is 9 3 94 5 dB. It still reaches 90 2 dB. Therefore, it is possible to determine the operating noise of two turbine air compressors and two oxygen compressors on the second floor plane, which is the sound source that constitutes the plane noise on the second floor, and forms reverberation in the equipment room and affects each other. From the sound level intensity comparison of each measuring point, the noise values ​​of the measuring points of the No. 1 oxygen compressor west of the No. 1 air compressor are 94 5 dB(A) and 94 2 dB(A), respectively. Close, while the measuring point of the No. 2 oxygen compressor is 91 5 dB(A), and the measuring point on the west side of the machine room is 90 4 dB(A), showing a significant decreasing trend. Therefore, the noise of the four machines in the equipment room is mainly based on the noise of two turbine air compressors.
On the first floor of the 3 machine room, the water coolers of the two turbine air compressors and the two oxygen compressors are installed on the first floor through the floor channel, and the process pipes are mainly arranged on the first floor. The noise on the first floor is mainly caused by the noise on the second floor being formed by the channel propagation between the floors and the connecting pipes, and the noise generated by the pump on the first floor is combined. The noise level A of each measuring point on the first floor of the plane air compressor water is 96 5 103 5 dB( A), which is obviously higher than the measuring points on the second floor plane. Therefore, the plane noise test on the second floor is blocked by the sound insulation board. It is a non-direct source, but the noise of the refraction and penetration is blocked by the sound insulation. The noise of the measurement points on the first floor plane is mainly the direct propagation noise of the floor channel (mounting hole).
2 3 Noise cause analysis and analysis: It is considered that the air compressor inlet noise has good noise reduction and noise reduction effect due to the configuration of the corresponding air intake filter; the air compressor basic design is reasonable, basically meets the vibration reduction requirements, and vibration causes The noise is not large; in addition, the remote location of the venting noise does not have a large impact.
According to the noise field monitoring and noise cause analysis of the air compressor system, the main noise sources that constitute the noise of the air compressor system are: (1) air compressor exhaust noise and transmission pipeline noise; (2) air compressor local noise.
2 3 1 Exhaust Noise Turbine The high-speed rotating impeller compresses the air when the air compressor is working, so that the inhaled outside air medium collides with the intense molecular collision in an instant, thereby increasing the pressure of the air medium. In this process, a considerable part of the energy is converted into Thermal energy and acoustic energy are radiated to the surrounding environment by means of the casing and the conveying pipe. The on-site monitoring results show that the noise value is as high as 106 7 dB(A) at 1 m from the machine (in the sound insulation enclosure), even at the noise points of the measuring points outside the second floor flat acoustic enclosure. 93 7 96 4 dB(A), the noise of each measuring point on the first floor plane is 96 5 103 5 dB(A), which is the noise that directly poses the most harmful to the operator of the equipment room.
2 3 2 Air compressor local noise The local noise is the inherent noise of the air compressor. It includes the mechanical noise generated by the impact of many components during the operation of the machine and the electromagnetic noise generated when the motor rotates. The turbo air compressor is a high-speed air compressor with a rotational speed of 12 000 r/min, which produces a strong mechanical noise.
3 According to the noise cause analysis, process conditions and operational requirements, the treatment plan adopted is as follows: 3 1 The main part of the turbine air compressor is silenced and the original waste acoustic enclosure is removed, and the new semi-automatic monitoring with air exhaust is installed. Combined sound insulation cover (with soundproof door, window) for sound insulation; set 2 SF7G-6N low noise axial exhaust fans, air volume is 22 000 m 3 / h; set 2 T KP- 960 exhaust muffler The air volume is 22 000 m 3 / h. The axial flow exhaust fan is controlled by semi-automatic electronic control to ensure ventilation and ventilation.
3 2 Partial sound insulation of the water cooler The original construction wall is used to replace the high-quality sound insulation door (combined sound insulation wall) with the original large iron gate for sound insulation treatment, and two groups (TKJ-960, TKJ-600) are set. Wind noise reduction and static pressure chamber are used for air noise elimination treatment, and soundproof box sound insulation treatment is applied to the valve pipe.
3 3 Air compressor exhaust pipe sound insulation in the engine room The air compressor exhaust pipe in the engine room is damped and sound-damped by sound-absorbing materials and flexible material wrapping to eliminate pipeline transmission noise.
4 After the implementation of the treatment effect project, the noise of the turbine air compressor system is significantly reduced. The monitoring data is as follows, and the maximum noise of the bottom layer of the equipment room is 91 dB(A), which meets the requirements of 2 hours of inspections per employee day; screaming High-frequency noise has been greatly reduced, meeting the requirements of industrial enterprise noise control design specifications (GBJ87-1985) and industrial enterprise design hygiene standards (GBZ1-2002).
5 Conclusion 1 Eliminate the harm of air compressor noise, we must adhere to the principle of prevention and prevention. On the one hand, low-noise equipment should be selected; on the other hand, the design, construction, layout, and mechanical equipment with strong radiation noise should be considered, and the noise control facilities should be designed and constructed simultaneously with the main project. Put into use principle.
2 Enterprises should arrange personal protective equipment such as earmuffs and helmets for workers entering high-noise workplaces to reduce noise hazards.
Outdoor Dinnerware,Outdoor Tableware,Melamine Outdoor Dinnerware,Outdoor Dinnerware Sets
Ningbo Watower Outdoor CO.,LTD , https://www.esygoing.com