Joined: Apr 2011
Monday April 25, 2011 02:32
Gas generator sets are comprised of gas fuel generator engine, generator, controller, etc parts. Gas engines and generators are installed in the same steel chassis. Generator with natural gas, coal gas, the chamber, refining tail gas, methane, coke oven gas, blast furnace gas etc for fuel, start the combudstible gas, economical, especially rapidly due to high quality demand by city life. Gas generating set has been widely used in telecommunications, post office, bank, libraries, hospitals, hotels, and other departments as the backup power supply. Initial gas generating set is designed for mining condition, when the unit operation of the noise is commonly 95 ~ 110 dB (A). GB 3096-93 urban areas of environmental noise standard downtown noise status of strict rules for two kinds area of residential, commercial, industrial (mixed zone) for 60 dB between day and night for (A), 50dB (A); For class 1 area (living, cultural authority area) for 55 dB between day and night, (A) for 45 dB (A). When the unit operation of the noise to the urban environment poses a serious noise pollution, it could affect people's normal work and life. Meanwhile it limits the extensive application of the gas generator. This article is aimed at gas generating set noise pollution problems, and put forward a set of corrective measures, hoping to reduce noise, promote unit the popularization and application of the gas generator.
1 source analysis
Gas engine noise is the main gas generator, gas engine noise sources of noise can be divided into aerodynamic noise, combustion noise, mechanical noise, exhaust noise and vibration noise. Air dynamic noise mainly includes the intake and exhaust and fan rotation cause air vibration noise, this part directly lead to airborne noise. By the formation of the cylinder combustion pressure cylinder body vibration through, the noise of the radiate outward called combustion noise; The piston cylinder liner the impact of valve-train, jet system moving parts generate impact vibration noise collectively referred to as mechanical noise. Unit work, exhaust gases out along the exhaust manifold high-speed burst into the muffler, finally from the tail pipe is vented to atmosphere. Exhaust noise is the biggest noise, often engine than engine host noise high 15 dB (A) or so, secondly respectively is combustion noise and mechanical noise, fan noise, the intake noise.
2 transformation design
Silencing the core is to use the technology in the spread of the sound in the natural attenuation to narrow noise pollution rules face. Specific reduces the noise method has the following kinds: sound absorption, sound insulation and change direction of noise propagation. In practical engineering application are often only one, this paper use three methods and measures for gas generating set, put forward new type composite noise reduction technology.
2.1 combination muffler
The original muffler attenuation is given priority to, with resistance sexual power, silencing effect is not ideal. After careful reasoning, application level 3 combination noise reduction technology, will transform for the new combined-type muffler. This combined the main components have muffler attenuation of reducing vibration chamber, spray porous type silencer masks and acoustic insulation layer and acoustic resonance plate, etc. Source through the first level of reducing vibration chamber to gush silencing, low noise will sound energy dissipation thorough resistance. The secondary porous type resistance sex silencing cover can eliminate to most of high frequency noise, increased the muffler on high-frequency adaptability, and in this chamber equipped with efficient absorption material of noise, the absorption and change to adequately, thus maximum limit consumption noise energy. 3 for a specially designed with resonant board exhaust enable further through the chip vibrations of the silencer. By test, new muffler attenuation quantity, silencing frequency range (mainly for silencing quantity of frequency range) and peak three indexes resistance losses than the original muffler. In addition the muffler size is appropriate, good rigidity structure, convenient installation, and has the function of renewable noise suppression. And the rear sound absorption layer has anticorrosive performance, can effectively overcome the low dew point corrosion flue gas, extend the service life of the muffler.
2.2 two-level isolation cushion
Control mechanical noise and a valid way of combustion noise isolation of units is handling. Gas machine, generators and steel chassis installed composite isolation between reducing vibration cushion, chassis and foundation also cushions to efficient between reducing vibration pads. After two levels of vibration isolation processing, make not only of the vibration is effective partition unit, and make the unit operation more smoothly, the overall noise significantly reduced.
2.3 silencing row duct
Fan noise is by rotating noise and eddy current noise composition. By rotating fan blades rotating noise produced cutting air flow caused periodic disturbance. Eddy current noise is happening on the rotating blades section boundary layer separation, the slippage or split and a series of vortex flow into, and radiation out a unsteady flow noise. Exhaust duct directly interconnect with the outside. Velocity of air flow noise and mechanical noise radiate out by this channel. In order to control the fan and exhaust channel noise, design a censored exhaust duct. The censored row duct the inlet length larger air exhaust slot and noise of cavity. Exhaust noise reduction cavity principle, similar to the resistance sex muffler. But by changing sound-absorbing materials (changing material sound-absorbing coefficient), change sound-absorbing material thickness, exhaust channel length and width to improve the effect of parameters such as mute.
2.4 silencing inlet port
Units operate in a closed room. Broadly speaking, air intake system includes units into wind channel and the engine intake system. Into wind channel and exhaust passages interconnect directly with the outside. The velocity of air flow noise and the all the operation noise of the unit evacuate into the wind. The engine intake system noise is formed by the pressure of the inlet valve open and close process, the noise frequency general in the low frequency range below 500 Hz. In the room wall sets up two silencing respectively, the inlet as room 2 and engine inlet. Because the indoor negative pressure caused by wind, cold air naturally goes into the room by silencing inlet, with the body heat released successfully, thus ensuring the room plenty of fresh air.
Article from : ET Power Machinery Co., Ltd.
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Edited: Friday October 28, 2011 at 05:52 by placido