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Views: 0 Author: Site Editor Publish Time: 2025-09-23 Origin: Site
A cooling tower is a device that cools water through the contact between air and water. Its main working principle is the circulation cooling of water. During this process, the cooling water absorbs heat from the system and is then discharged into the atmosphere. This article aims to delve deeply into the design, selection of cooling towers and the necessity of noise reduction treatment, with the expectation of providing readers with a comprehensive understanding.
Noise control for cooling towers is of vital importance. Generally, it is necessary to comply with the second-class standards stipulated in the "Environmental Noise Quality Standard" GB3096-2008, ensuring that the noise level in residential areas does not exceed 60dB during the day and 50dB at night. The main noise sources of cooling towers include fans, water drops, water pumps and motors, among which the noise from fans is particularly prominent. It includes wideband air turbulence noise (medium frequency to high frequency) and blade rotation noise (low frequency). To reduce this kind of noise, measures such as installing mufflers or sound barriers can be taken.
An effective way to reduce the noise of fans is to install appropriate silencing devices at the exhaust port. The impedance composite muffler performs exceptionally well. By ingeniously combining sound absorption and sound reflection technologies, it can effectively eliminate noise over a wide frequency band. This muffler not only possesses the ability of resistive mufflers to eliminate medium and high-frequency noise, but also incorporates the control effect of reactive mufflers on low and medium-frequency noise, thereby achieving comprehensive noise reduction.
Fans generate rotational and turbulent noise, and their characteristics are closely related to factors such as airflow velocity and blade shape. Rotational noise is caused by the pulsation generated when the blades rotate and is closely related to the number of blades, gas flow rate and static pressure, etc. Its spectrum shows narrowband low and medium frequency characteristics. The intensity of turbulent noise is directly proportional to the sixth power of the relative velocity of the airflow and is closely related to factors such as blade shape. Its spectrum is continuous.
The noise caused by water spray is related to the impact of water droplets. It is generated during the operation of the cooling tower when the water droplets falling from the water spray device collide with the accumulated water on the base of the tower. Its noise level is closely related to the height of the drop and the water flow per unit time.
The noise of water spray usually ranks after the noise of the fan in the noise spectrum and shows high-frequency characteristics. When the noise of the fan is effectively controlled, the problem of water spray noise becomes increasingly prominent. For the noise caused by water splashing, sound barrier treatment measures can be taken. Installing sound-absorbing devices or sound insulation barriers at the air inlet can effectively reduce the impact of water splashing noise.
It should be noted that when installing the sound insulation barrier, it is necessary to ensure that it is kept at a distance of about 1 meter from the air inlet of the cooling tower's louvers to guarantee that the ventilation air inlet of the cooling tower is unobstructed and thus does not affect its cooling effect.
In addition, to further enhance the noise reduction effect, a sound barrier of a certain length can be installed near the sound-absorbing deflector plate to prevent the influence of noise diffraction on the acoustic effect of the sound-absorbing deflector plate.
In the process of controlling water spray noise, it is necessary to take into account the performance of heat dissipation to avoid affecting the normal operation of the cooling tower due to sound insulation treatment measures. At the same time, when designing and selecting equipment such as mufflers and sound-absorbing louvers, the requirements of heat dissipation performance and dynamic performance should be comprehensively considered to ensure the noise reduction effect without reducing the cooling capacity of the cooling tower or adding unnecessary resistance.
The noise of these devices is relatively lower than that of fans, but it still requires attention under specific conditions. During the operation of the reducer and the motor, a certain amount of noise will be generated due to the meshing of gears. In addition, motors also generate electromagnetic noise and mechanical noise, but these two types of noise usually have a relatively small impact on the surrounding environment and can be ignored.
The circulating water pumps that are matched with cooling towers are usually located near the cooling towers. Due to the resonance of water pipes, they will produce high-frequency noise. When the operating power of the water pump is relatively high, solid sounds will also be produced. Therefore, when noise or vibration problems are prominent, both the water pump and the cooling tower need to be treated simultaneously.
For the fans installed on the roof, their low-frequency vibration can spread to distant places within the building structure, and the low-frequency structural sound they generate has a significant impact on some high-demand rooms. Therefore, vibration reduction measures must be taken. Generally, the installation interval of shock absorbers should not exceed 2 meters. Based on this, the number of spring shock absorbers required can be calculated.
It is recommended to use restrictive spring shock absorbers. Their feature is that they are equipped with height limit devices, which are suitable for equipment with large variations in operating weight. They prevent significant changes in machine height after shock absorption, thereby protecting the equipment structure. In addition, the noise of the fan can also be controlled by replacing it with low-noise fan blades. The specific method should be selected based on the actual situation.
