Environmental impact assessment engineer: ground noise reduction measures are usually adopted in generator rooms

When running, diesel generator sets usually produce noise of 95 ~ 128db (a). If the necessary noise reduction measures are not taken, the noise of unit operation will cause serious damage to the surrounding environment. In order to protect and improve the environmental quality, the noise must be controlled.

The main noise sources of diesel generator sets are all generated by diesel engines, including exhaust noise, mechanical noise and combustion noise, cooling fan and exhaust noise, air intake noise, generator noise and ground vibration transmission noise, etc. :

1. Exhaust noise. Exhaust noise is a kind of high temperature, high speed pulsating gas flow noise, which is the largest energy in the engine noise, the noise can reach more than 100db, is the main component of the total engine noise.

2. Mechanical noise and combustion noise. Mechanical noise is mainly caused by the vibration or mutual impact caused by the periodic change of gas pressure and inertia force in the running process of each moving part of the engine. It has the characteristics of long noise propagation and decline reduction. Combustion noise is the structural vibration and noise of diesel oil during combustion.

3. Cooling fan and exhaust noise. Fan noise is composed of eddy current noise, rotating noise and mechanical noise. Exhaust noise, airflow noise, fan noise and mechanical noise will be transmitted through the exhaust channel, thus causing noise pollution to the environment.

4. Incoming wind noise. The function of the air inlet channel is to ensure the normal operation of the engine and to create good heat dissipation conditions for the unit itself. The air inlet channel of the unit must be able to make the air inlet smoothly into the machine room, but at the same time the mechanical noise and airflow noise of the unit will radiate to the outside of the machine room through the air inlet channel.

5. Transmission noise of foundation vibration. The strong mechanical vibration of the diesel engine can be spread far and wide through the ground and then radiated through the ground.

The principle of noise reduction treatment is to ensure that the diesel generator set ventilation condition, that is, do not reduce the output power under the premise, the use of high-efficiency sound absorbing materials and noise reduction and noise elimination device for the intake and exhaust channels and exhaust system for noise reduction treatment, so that the noise emissions meet the national standard (85dB (A)).

The most fundamental way to reduce the noise of generator is to start from the sound source and use some conventional techniques to reduce the noise. Such as muffler, sound insulation, sound absorption, vibration isolation is the most effective way.

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 to control. The use of a special impedance composite muffler can generally reduce exhaust noise 40-60db (a).

2. Reduce the noise of axial flow fan. When reducing the noise of the cooling fan of the generator set, two problems must be considered. The second is the required amount of noise. For the above two points, the resistive chip muffler can be used.

After effectively reducing the noise, in order to make the machine room environment more beautiful and practical, usually outside the sound absorption layer of the wall and the ceiling is also decorated with a micro-porous aluminum plastic punching plate, at the same time a reasonable configuration of lighting system.