Mar. 21, 2022
When diesel generator set is running, it usually produces 95 ~ 128dB (A) noise. If necessary noise reduction measures are not taken, the noise of genset operation will cause serious damage to the surrounding environment. In order to protect and improve environmental quality, noise must be controlled.
The main noise sources of diesel generator set are generated by diesel engine, including exhaust noise, mechanical noise and combustion noise, cooling fan and exhaust noise, inlet noise, generator noise, noise generated by the transmission of foundation vibration, etc.
(1) Exhaust noise. Exhaust noise is a kind of pulsating air flow noise with high temperature and high speed. It is the most energy in the engine noise. Its noise can reach more than 100dB. It is the most important part of the total engine noise. The exhaust noise generated during the operation of generator is directly discharged through the simple exhaust pipe (the original exhaust pipe of the generator set), and the noise frequency increases significantly with the increase of air flow speed, which has a serious impact on the life and work of nearby residents.
(2) Mechanical noise and combustion noise. Mechanical noise is mainly caused by the vibration or mutual impact of the moving parts of the engine caused by the periodic changes of gas pressure and motion inertia force during operation. It has the characteristics of long noise propagation and reduced attenuation. Combustion noise is the structural vibration and noise produced by diesel during combustion.
(3) Cooling fan and exhaust noise. The fan noise of the unit is composed of eddy current noise, rotating noise and mechanical noise. Exhaust noise, air flow noise, fan noise and mechanical noise will be transmitted through the exhaust channel, resulting in noise pollution to the environment.
(4) Incoming noise. The function of the air inlet channel is to ensure the normal operation of the engine and create good heat dissipation conditions for the unit itself. The air inlet channel of the unit must enable the air inlet to enter the machine room smoothly, but at the same time, the mechanical noise and air flow noise of the unit will also be radiated outside the machine room through this air inlet channel.
(5) Transmission noise of foundation vibration. The strong mechanical vibration of diesel engine can be transmitted to outdoor places through the foundation, and then radiate the noise through the ground.
The principle of noise reduction treatment in diesel generator room is to use sound-absorbing materials and noise reduction and silencing devices to reduce the noise of air inlet and exhaust channels and exhaust system on the premise of ensuring the ventilation conditions of diesel generator set, that is, without reducing the output power, so as to make the noise emission meet the national standard 85dB (A).
The most fundamental way to reduce generator noise is to start from the sound source and adopt some conventional noise reduction technologies; For example, muffler, sound insulation, sound absorption and vibration isolation are the most effective methods.
(1) Reduce exhaust noise. Exhaust noise is the main noise source of the unit, which is characterized by high noise level, fast exhaust speed and great difficulty in treatment. The exhaust noise can generally be reduced by 40-60dB (A) by using a special impedance composite muffler.
(2) Reduce the noise of axial flow fan. When reducing the noise of cooling fan of generator set, two problems must be considered: one is the allowable pressure loss of exhaust channel. The second is the required silencing amount. For the above two points, resistive chip muffler can be selected.
(3) Sound insulation and absorption treatment of the machine room and vibration isolation of diesel generator.
1) Sound insulation of machine room. After the exhaust noise and cooling fan noise of the diesel genset are reduced, the remaining main noise sources are diesel engine mechanical noise and combustion noise. Except for the necessary internal wall observation window connected with the observation room, all other windows shall be removed, all holes and holes shall be tightly blocked, and the sound insulation of brick wall shall be more than 40dB (a). The doors and windows of the machine room are fireproof and sound insulation doors and windows.
2) Air inlet and exhaust. After the sound insulation treatment of the machine room, the problem of ventilation and heat dissipation in the machine room shall be solved. The air inlet shall be set in the same straight line with the generator set and exhaust outlet. The air inlet shall be equipped with a resistive chip muffler. Since the pressure loss of the air inlet is also within the allowable range, the air inlet and outlet in the machine room can be naturally balanced, and the ventilation and heat dissipation effect is obvious.
3) Sound absorption treatment. The five walls in the machine room except the ground can be treated for sound absorption, and the perforated plate resonance sound absorption structure is adopted according to the frequency spectrum characteristics of the generator set.
4)The exchange of indoor air and the good sound insulation of the machine room will prevent the air in the machine room from convection when the closed water-cooled generator unit is shut down, and the high temperature in the room can not be reduced in time. The problem can be solved by using low-noise axial flow fan and resistive plate muffler.
5) Vibration isolation of the unit. Before the installation of electric generators, the vibration isolation treatment shall be carried out in strict accordance with the relevant data provided by the manufacturer to avoid the long-distance transmission of structural sound, and the air sound shall be continuously radiated in the transmission, so that the noise level at the plant boundary cannot meet the standard. For the existing generator set requiring treatment due to exceeding the standard, the vibration of the ground near the unit must be measured. If the vibration feeling is obvious, the generator set must be isolated first.
After effectively reducing the noise, in order to make the environment of the machine room more beautiful and practical, the sound-absorbing layer of the wall and ceiling is usually decorated with microporous aluminum-plastic perforated plate, and the lighting system is reasonably configured.
Jun. 25, 2022
Get in Touch