How to control the noise of cement factory
Date：2019-08-22 17:13 Source：cementepcViews:
Noise is after dust pollution in the production of cement plant, widely used in existing cement production large crusher, grinding machine, high pressure blower, air compressor, such as equipment, above the noise of the equipment at work tend to be as high as 120 db (A), well above the national standard of less than 85 db (A), in addition to these devices is often 24 hours A day at work, long so work ceaselessly, thus for cement production personnel in the area and the surrounding environment within the border of A lot of pollution.
1. Noise source of cement factory
The main working places of cement factories are noise sources, and some of the whole machine room is in the state of high noise, which seriously damages the physical and mental health of operators.Therefore, to control noise within the permissible range as soon as possible is in line with the requirements of modern development.Generally speaking cement factory needs to govern a few significant noise sources have:
(1) raw material grinding area equipment:
Vertical mill, vertical mill exhaust fan, kiln tail exhaust fan, high temperature fan, kiln tail electrical dust collector exhaust fan;
(2) kiln head area:
Grate cooler fan group, kiln head roots fan, clinker electric dust collector fan;
(3) coal mill:
Coal mill, roots fan;
(4) cement grinding workshop:
(5) homogenized storage area:
(6) air compressor room:
2. Noise characteristics of related equipment in cement plant
2.1. Noise characteristics of ball mill:
Cement factory ball mill noise is the largest, large ball mill noise in 120 db or so, generally with the plant sound insulation and the use of sound-absorbing materials to absorb ball mill noise.The development direction of pulverizing technology is to use vertical mill instead of ball mill, not only the grinding efficiency is higher than ball mill, but also the noise problem is solved at the same time.The use of outdoor layout, noise problems can completely meet the environmental requirements.The same effect can be achieved by using roller pre - grinding technology.The noise of the ball mill mainly includes: electromagnetic noise produced by the motor in the running of the mill;Mechanical noise generated by gear of reducer;Mechanical vibration noise produced by grinding material and lining plate grinding each other in the rotation of drum;Aerodynamic noise generated by fans of dust removal equipment and classification equipment;And the sound of solids radiating through the base vibrations.The noise characteristic of the ball mill is related to its type, specification, revolution, particle size of abrasive and material, filling coefficient and other factors.
2.2 noise characteristics of roots blower
The noise of high pressure fan is about 100 db, the number of fan of cement factory is more, the noise problem of fan is relatively more outstanding.The noise of roots blower mainly includes: aerodynamic noise radiated by intake and exhaust;Mechanical noise radiated by tube wall and motor;Solid sound and electromagnetic noise radiated by foundation vibration.The noise characteristics of roots blower are generally related to the flow rate, rotating speed, static pressure and other factors.
2.3 noise characteristics of air compressor
The noise of traditional air compressor is also very high. The technology of screw compressor can reduce the noise and meet the requirement of environmental protection.Roots blower noise at high pressure is quite large, China is currently developing and using three-leaf roots blower, three-leaf roots blower than two-leaf roots blower can reduce about 10 db noise, at the same time energy saving 10% ~ 20%.The fundamental frequency of air compressor is generally about 20 hz, its high harmonic frequency is generally in the tens to hundreds of hz, therefore, the air compressor intake noise is a typical low frequency.Air compressor intake noise intensity with the increase of air compressor load and increase, the general intake noise than other parts of the air compressor noise higher than 7 ~ 10 db (A).
3. Common methods of noise control
The fundamental way to prevent and control noise is to start with its source.For mechanical and electrical equipment, manufacturing, machining precision and installation meet the specified requirements, can reduce noise;The vibration noise of the foundation can also be reduced by inserting damping materials (such as rubber pads, plastic parts) or damping materials (such as elastic metal sheets, springs) between the equipment and the foundation.The second is to control the spread of noise.When the sound intensity of the noise source cannot be reduced to the allowable range, barriers must be erected during the noise propagation so that the sound energy will be reflected and attenuated during the propagation.
The usual methods are:
Some sound waves are reflected back by materials with high density and high characteristic impedance, and the noise is confined to the vicinity of the noise source to reduce the radiation energy of the noise.If the inner wall is installed with sound absorbing damping material, the effect is better.Sound insulation cover is added around the mill. The inner wall of the cover is made of sound absorbing material and damping material.There is another way for the mill is to use a wall between the grinding body and its drive device, and add a double-layer sound insulation door on the wall, which can reduce the transmission of noise.
Some of the energy of sound is absorbed and converted into heat energy by means of a porous, soft material that produces viscous and frictional effects on sound waves.Can be installed in the building sound absorption materials (such as glass felt or glass board, slag cotton, felt and foam plastic, foreign cork made of sound absorption brick;When the sound absorbing material is 25mm thick, it can absorb high-frequency noise, but hardly absorb low-frequency noise.The absorption of low frequency noise is better when the thickness of sound absorbing material increases to 50 ~ 100mm).Sound insulation and sound absorption structures should have a greater impedance to vibration to avoid secondary noise.
(3) the use of noise elimination method:
For example, mufflers are set at the inlet and outlet of fans, compressors and air ducts.But it can only have certain muffling effect on individual equipment or pipe parts.
(4) use of human body protection:
When people have to work in A high-noise environment for A long time or engage in short-term work in A high-noise environment of 115dB(A) or above, earplugs, earmuffs or helmets can be used for human protection.
It is suggested that the noise prevention scheme should be taken into account in the overall design of the newly built cement enterprises, and the cement production enterprises should also pay attention to the noise pollution and make necessary investment to meet the needs of modern civilized production.If you have any more questions about cement plants, please contact us. We will reply to you as soon as possible.