Solutions to noise reduction of emergency generator

the types of electric power generation is a kind of mechatronics equipment that converts the chemical energy of fuel into electrical energy. Today, with the increasing modernization, especially with the vigorous development of computer networks and communications, the equipment also has requirements for the reliability of power supply. Increasingly, because the UPS power supply has the problem of short power supply time. This makes diesel generator sets have a broad space for development, but while diesel silent generator provide convenience for people, the noise of the generator sets directly affects people's health, work and life. With the gradual improvement of people's environmental requirements, how to solve and overcome the above problems has become the key to the application and development of diesel generator sets. Here we focus on the occurrence and solutions of diesel generator sets.

According to the working principle of diesel generator sets, the generation of noise is very complicated, which can be divided into the reasons and locations: 1. Exhaust noise; 2. Mechanical noise; 3. Combustion noise; 4. Cooling fan and exhaust noise; 5 .Inlet wind noise: 6. Generator noise.

The following is an explanation of these six parts:

1. Exhaust noise:

Exhaust noise is a high-temperature, high-speed pulsating airflow noise, which is the most energy and component part of engine noise. It is much higher than the intake noise and the mechanical noise radiated by the body, and it is the most important part of the total engine noise. Its fundamental frequency is the firing frequency of the engine. The main components of exhaust noise are the following: low-frequency pulsating noise caused by periodic exhaust smoke, air column resonance noise in the exhaust pipe, Helmholtz resonance noise of the cylinder, high-speed airflow through the valve gap and tortuous pipes When the noise, eddy current noise, and the regenerated noise generated by the pressure wave in the exhaust system are excited by the pressure wave in the pipe, the noise frequency increases significantly with the increase of the airflow speed.

2. Mechanical noise:

Mechanical noise is mainly caused by the gas

Vibration or mutual impact caused by the periodic changes of pressure and motion inertia force, the most serious of which are the following: the noise of the piston crank connecting rod mechanism, the noise of the valve train, the noise of the transmission gear, and the unbalanced inertia Mechanical vibration and noise caused by force. The strong mechanical vibration of the diesel generator set can spread to various places outdoors through the foundation long distance, and then form noise through the radiation of the ground. This kind of structural noise spreads far and attenuates, and once it is formed, it is difficult to isolate it.

3.Combustion noise:

Combustion noise is the structural vibration and noise produced by diesel fuel during combustion.

The sound pressure level of combustion noise in the cylinder is very high. However, most parts of the engine structure have high rigidity, and their natural frequency is mostly in the middle and high frequency region. Due to the mismatch of the frequency response to the sound wave propagation, it is because in the low frequency range. The very high peak cylinder pressure level cannot be transmitted smoothly, while the cylinder pressure level in the mid-to-high frequency range is relatively easy to transmit.

4. Cooling fan and exhaust noise:

The fan noise of the unit is composed of eddy current noise and rotating noise. The rotating noise is caused by the periodic disturbance of the cutting air flow of the fan blade: eddy current noise is generated when the airflow separates on the rotating blade section and is caused by the viscosity of the gas. The vortex current radiates an unstable flow noise. Exhaust noise, airflow noise, fan noise, and mechanical noise are all radiated through the exhaust channel

5. Inlet wind noise:

Diesel generator sets need to have enough fresh air supply when they are working normally, on the one hand to ensure the normal operation of the engine, on the other hand, to create good heat dissipation conditions for the unit, otherwise the unit cannot guarantee its performance. The air inlet system of the unit basically includes the air inlet channel and the air intake system of the engine itself. The air inlet channel of the unit must enable the fresh air to enter the engine room smoothly. At the same time, the mechanical noise and airflow noise of the unit can also be radiated to the engine room through this air inlet channel. Outside.

6. Generator noise:

Generator noise includes electromagnetic noise caused by magnetic field pulsation between stator and rotor, and mechanical noise caused by rolling bearing rotation.

According to the above noise analysis of diesel generator sets. Generally, the following two treatment methods are used for the noise of the generator set:

The oil engine room is used for noise reduction treatment or when purchasing a soundproof unit (its noise is 80db--- 90db).

The noise reduction in the computer room needs to deal with the above noise causes separately, mainly

There are the following methods:

1. Noise reduction for inlet and exhaust air: the air inlet and exhaust channels of the computer room are separately insulated

The wall, the air inlet channel and the exhaust air channel are equipped with silencers. There is a certain distance in the channel for buffering, so that the intensity of the sound source radiated from the computer room can be reduced.

2. Control of mechanical noise: The top and surrounding walls of the machine room are equipped with sound-absorbing and sound-insulating materials with high sound absorption coefficient, which are mainly used to eliminate indoor reverberation and reduce the sound energy density and reflection intensity in the machine room. In order to prevent noise from radiating outward through the gate, set fire-proof iron gates

3. Control of smoke exhaust noise: the smoke exhaust system is based on the original-grade silencer

The installation of a special two-stage silencer can ensure the effective control of the exhaust noise of the unit. If the length of the exhaust pipe exceeds 10 meters, the pipe diameter must be increased to reduce the exhaust back pressure of the generator set. The above treatment can improve the noise and back pressure of the generator set. Through the noise reduction treatment, the noise of the generator set in the machine room can meet the user's requirements outdoors.

Noise reduction in a computer room generally requires sufficient space in the computer room. If the user cannot provide a computer room with a sufficient area, the noise reduction effect will be greatly affected. It can not only ensure the control of noise, but also enable the normal operation of the generator set. Therefore, air inlet channels, exhaust channels, and operating space for staff must be set up in the machine room.

Low-noise engineering design of diesel generating set engine room

When a diesel generator set is running, it usually produces a noise of 95-110db(a),

If the necessary noise reduction measures are not taken, the operating noise of the unit will cause serious damage to the surrounding environment. In order to protect and improve environmental quality, noise must be controlled. The requirements of national standards gb12348-90 and gb12349-90 for environmental noise are: Class II standards (applicable to residential, commercial, industrial mixed eastern areas and commercial central areas) 60db (a) during the day and 50db (a) at night; Class III standards (Applicable to industrial areas) 65db(a) during the day and 55db(a) at night. Low-noise engineering design is usually carried out according to the standard of 60db(a) in the daytime.

AI POWER uses high-efficiency sound-absorbing materials and advanced production technology

The noise reduction and noise reduction device of chemical production has carried out noise reduction treatment on the air inlet and exhaust channels and exhaust system to ensure that the unit can fully meet the national standards for environmental noise under the premise of meeting the ventilation conditions, that is, without reducing the output power. Require. The company has formed a unique low-noise engineering design code in many years of design and construction practice.

Two, design ideas

Diesel generator set is a complex machine with multiple sound sources.

Different types, sizes, and operating conditions have different effects on the total noise of each sound source. In general, the various types of noise of the unit are roughly arranged in the following order: exhaust noise, combustion noise or mechanical noise, fan noise, intake noise Air noise. The basic idea of noise reduction design is: first find out the maximum noise component and its frequency characteristics in various sound sources, and take relevant technical measures to reduce the noise level of each sound source to approximately the same level as much as possible, among which the noise that is easy to reduce The source can be reduced more, and the noise reduction must be considered in conjunction with other technical requirements (such as the impact on the output power of the unit, the noise reduction cost and other specific factors).