Cooling tower noise evaluation index

At present, there are two different evaluation indexes for cooling tower noise, one of which is the national product standard GB/T7190.1-1997 and GB/T7190.2-1997 "glass fiber reinforced plastic cooling tower for cooling tower design and manufacturer. 》, the standard for the different circulating water volume and model of the product specified user's national standard GB3096-2008 "acoustic environmental quality standards", the standard for different environmental areas specified zui high sound level.

Cooling tower noise control status

If the enterprise produces cooling towers according to the high limit of GBi of GB/T7190.1-1997 and GB/T7190.2-1997, all products can not meet the national standard GB3096-2008 for nighttime noise of the second class below ≤45~50dB(A) The requirements are that only a few low-tonnage ultra-low noise models of cooling towers can meet the requirements of nighttime noise standards in a small number of areas.

At present, the noise reduction measures of the cooling tower are not effective. For example, the sound barrier is incapable of the diffraction of low-frequency waves. The sound insulation cover will hinder the flow of the airflow, resulting in poor heat and humidity exchange, and the sound absorption effect on broadband noise is poor, which makes the cooling tower Noise control has received increasing attention.

Therefore, the residents around the cooling tower and the government's environmental protection department require the cooling tower users to control the noise pollution generated by the cooling tower according to the national environmental noise standard GB3096-2008.

The cooling tower noise source is mainly composed of the following four parts:

1) Fan inlet and exhaust noise;

2) water spray noise;

3) fan reducer and motor noise;

4) Cooling tower water pump, piping and valve noise.

Sound source attribute: The noise source is a huge circular water surface under the falling water area, which is the steady-state water noise generated by the large-area continuous liquid collision of the pool water in the tower; it is mechanical noise, aerodynamic noise and electromagnetic noise. A special kind of noise.

Cooling tower noise reduction principle

When sound waves encounter obstacles in the process of propagation, reflection, transmission and diffraction occur. The sound barrier is to insert a device between the sound source and the sound receiving point to block and absorb the direct sound wave from the sound source to the sound receiving point, so that part of the sound wave is blocked and reflected, and some sound waves are absorbed and attenuated and transmitted through the screen body. The additional attenuation form such as small) and the top of the screen reaches the sound receiving point, so as to reduce the noise influence of the sound receiving point and achieve the purpose of noise reduction.

Fan low frequency noise control:

The choice of muffler is very important. The general muffler has no obvious effect on the low-frequency noise. The resistance muffler has good control effect, but the frequency selectivity is very strong. Therefore, the impedance composite muffler is generally selected.

An impedance composite muffler is a muffler that combines sound absorption and acoustic reflection properly. It also has a resistive muffler to eliminate medium and high frequency noise and a resistant muffler to eliminate low and medium frequency noise characteristics, and has a wide-band noise cancellation effect.

Jiangsu Jincheng Air Conditioning Engineering Co., Ltd. focuses on:

Industrial air conditioners, chemical fiber industrial air conditioners, chemical fiber industry refrigeration, textile industry air conditioners, clean room refrigeration, ventilation ducts, cooling towers, refrigeration machines and other air conditioning units and accessories.

If you want to know more about the product, please contact: Mr. Song 13705113637 Website: http://www.taocunbao.cn/