How to control the noise and vibration of industrial refrigerators

How to control the noise and vibration of industrial refrigerators

When industrial refrigerators are used, noise is unavoidable. Noise is the primary parameter to measure the performance of industrial refrigerators. It is directly related to the impact of industrial refrigerators on the surrounding environment. The sound level noise of centrifugal chiller A currently selected abroad is usually between 85 ~ gOdB. When understanding the noise target of any commodity, it is necessary to clarify the following two points:

　　 1. Whether the test environment for the noise level of industrial refrigerators is tested on-site or in a silent room.

　　2. To understand the distance between the measuring point and the industrial refrigerator (usually divided into lm and 3m). Industrial refrigeration units and other equipment generate loud noises, and equipment oscillations are transmitted to floors, walls and other structures along the foundation, which also arouses strong solid oscillation noises, severely disturbing everyone's operations and harming the health of operators.

　　 One, noise source analysis

　　1. The noise of industrial refrigerators is mainly composed of airflow noise caused by the reverse rotation of the compressor rotor of the industrial refrigerator, motor noise, throttle valve and auxiliary equipment noise. The oscillating energy of the industrial refrigerator unit is mainly caused by the unbalanced centrifugal force of the rotation. Motor noise includes airflow noise of cooling fan, electromagnetic noise, mechanical noise of bearing, and airflow noise of electric fan is the main component.

　　2. The noise of industrial refrigerator water pump unit mainly includes industrial refrigerator motor noise and water pump noise. The oscillation energy of the pump unit is mainly distributed in the straight direction, which is caused by the weight-induced vibration in the straight direction due to the unbalanced centrifugal force of the rotation.

　　3. Mechanical oscillations cause greater noise. The industrial refrigeration unit and the water pump and the pool cover are all rigidly connected, and the cover is simply excited to oscillate. The vibration of the industrial refrigerator machine is transmitted around the solid medium such as the floor, the wall and the pipe network of the machine, forming a structure-borne sound, and the structure-borne sound is then converted into airborne sound, forming noise radiation.

The primary factors affecting the noise of industrial refrigerator centrifuges are the transmission gears and unit exhaust (the exhaust noise of the centrifuge is large and some comes from the high-speed movement of the gas in the exhaust pipe). Regarding the former, the three-stage centrifugal can be better treated For the latter, the following two methods are very useful.

　　 1. Optional refrigerant spray equipment on the discharge side of industrial refrigerator compressors. The device sprays the refrigerant liquid to the exhaust side through the radial port, the mist-like refrigerant generated by the spray liquid has a sound absorption function, and its flash vapor can cool the compressor exhaust.

　　2. Choosing a noise reduction pad made of sound-absorbing materials and wrapping it on the exhaust pipe can usually reduce the A sound level noise by 2~4dB.

　　 2. Energy conditioning and surge

　　The energy conditioning methods currently selected by various manufacturers in centrifugal chillers generally include imported guide vane conditioning, industrial refrigerator compressor frequency conversion speed regulation ten-day leaf diffuser width regulation, and some manufacturers summarize the above methods together for conditioning. Different energy conditioning methods are a very important element in determining the surge point of the centrifuge.

　　1. The general guide vane is used for conditioning, and its surge point is between 20 and 30 loads, and the units of different brands are different.

　　2. The selection and adjustment of imported guide vanes are supplemented by the frequency conversion speed regulation of industrial refrigerator compressor impeller, and the surge point can be controlled at 10 loads.

　　3. The imported guide vane adjustment is supplemented by the width adjustment of the diffuser of the industrial refrigerator compressor, and the surge point can be controlled at 10 loads.

　　4. Regarding the selection of industrial refrigeration units, each level of import is equipped with vent guide vane conditioning, and its surge point can also be controlled at 10 loads.