Solution to noise in pneumatic conveying
? ? ?Radiation from the intake and exhaust portsNoise,The fan casing radiates noise outward, and the foundation vibration radiates noise into space. To address these issues, the following methods can be used.
? ? 1) Install silencers for inlet and outlet noise. The simplest and most effective way to control the radiated noise from the inlet and outlet of a fan is to install mufflers at the inlet and outlet of the fan. The so-called muffler is a noise control device that can prevent sound propagation and allow airflow to pass through. Installing a muffler at the inlet and outlet of a fan can generally reduce the noise radiated outward by 20-30 dB. The installation position of the muffler is usually close to the inlet or outlet of the fan, so that the noise emitted by the fan first passes through the muffler and then enters the pipeline. This can reduce the direct propagation of fan noise from the inlet and outlet to the outside, and also reduce the noise transmitted through the pipe wall.
? ? There are many structural forms of mufflers, which can be divided into resistive mufflers, resistant mufflers, and impedance composite mufflers according to the principle of noise reduction. At present, most of the silencers used for fans both domestically and internationally are resistive silencers, while the complex and bulky resistive silencers are gradually being used less.
? ? 2) Setting up soundproof enclosures for the external radiation noise of fan casings results in dynamic noise, but it is not possible to control the external radiation noise of the casings. The most effective and convenient method to control the external radiation noise of the fan casing is to use soundproof enclosures or soundproof rooms to seal the sound source - the aerodynamic mechanical seal - in a small spatial range, isolating the noise from the working environment of people. To achieve good sound insulation effect, the following two points must be noted in the design of sound insulation covers:
? ? ① The wall material of the soundproof enclosure should have sufficient sound insulation.
? ? ② The sound absorption coefficient of the inner surface of the cover should be as high as possible. Therefore, when designing a steel plate soundproof cover, a layer of ultra-fine glass fiber with high sound absorption coefficient is usually tightly attached to the inner wall of the cover to improve the sound absorption effect of the steel plate and increase sound absorption. The absorption speed of commonly used sound-absorbing materials.
? ? 3) Install shock absorbers for solid sound radiation from basic vibrations into space. When the aerodynamic machinery is directly installed on a rigid support structure, the equipment operates and generates solid sound due to vibration force. This noise can sometimes be transmitted further and stronger than airborne noise, affecting the quietness of the entire building and becoming a very annoying source of noise. To reduce the solid sound caused by the vibration transmitted to the foundation by these devices, a vibration isolation system is installed between the fan and the foundation, consisting of vibration isolation materials such as rubber, cork, felt, and shock absorbers, to attenuate the vibration transmitted from the vibration source to the foundation.