Noise Reduction
© BMU / Thomas Härtrich / transit
Effective noise control is particularly important in high-density residential areas and industrial premises, since it is not only annoying, but can even be harmful to health. The results of various studies have shown that noise causes hearing damage and significantly increases the risk of heart attack, especially in men.
In Germany, too, the population is exposed to many sources of noise. Automobile and airplane traffic, construction work, and the operation of technical machinery and plants in industry and commerce are particularly disturbing.
It is, nevertheless, possible to combat the problems of noise in modern industrial society. First research was required into the extent and effects of noise, in order to set noise level limits and noise protection requirements.
The following actions from research and development programs to reduce noise levels in the areas mentioned are illustrated on this platform:
- Street noise can, for example, be reduced through the use of two-layer, open-pore asphalts or innovative rubber mixtures for car tires.
- By converting trash collection trucks to low-noise technologies, the sound level in their working cycle and the impulse duration of operating noise can be minimized.
- Good examples of the further development and introduction of low-noise technology in industry and commerce are the use of membrane noise dampeners in vacuum pumps for paper production and, better design of movements in the case of fully mechanized round timber stations in sawmills.
Noise emission was reduced by 5 to 7 dB(A) by increasing noise reduction measures of numerous individual sources. The implemented noise reduction measures are conventional: sound absorbers for the fresh air intake valve of the blocks and the waste air system of the machine house (while considering the problems of loss of pressure) as well as acoustic measures for the fresh air channels. Only when noise of all the noise emitters was reduced simultaneously was the desired lowering of the overall noise level to 100 dB(A) achieved (further information in German).
Expand…
Source:
Federal Environment Agency (UBA)
Categories:
In order to reduce the noise level a low-noise road clearing vehicle with a rated driving power < 50 Kw has been developed. The scope of this development not only covers the vehicle itself but also the attachments typically used during the winter season. Changes in the design of the vehicle itself as well as of the attachment have resulted in a noise level reduction of 10 dB (A) when the vehicle is in operation.
Expand…
Development of active oscillating bedding to reduce sound emissions of wind driven power stations - laboratory tests
A new oscillation-insulating concept for structure-borne noise has been introduced. Conversion was achieved with load-bearing interfaces. Compared with passive bearing elements, the active interfaces feature a better insulation behavior for structure-borne noise within the range of 200 to 1000 Hz. A constructive integration of the interfaces into the bearing of a gear of a wind-driven power station is possible but does require a detailed design and construction of the gearbox bearing for conversion to take place. Bearings for devices with lower loads can utilize the new structure-borne noise insulating bearing elements with relatively little construction expenditure (detail information in German).
Retrofitting the trash collection trucks lowered the noise level during work cycles by at least 5 dB(A) to 97 dB(A) and the pulse duration of the work noise from 9 dB(A) to 2 dB(A). To reduce the impact noise when emptying containers into the truck the hydraulic controls were changed so that the hydraulic cylinders are retarded before impact. The especially noisy individual aggregates of the hydraulics system were replaced as well and the container tank of the trucks were sound-deadened with a plastic bitumen mass. Trash transcontainers were also designed with a new lid construction, among other changes.
Expand…
Mufflers and absorbing blinds were installed in the existing rail fleet as a means of complying with the statutory noise limits for new rolling stock in force in the European Union since 2006 without much investment or development work being necessary.
Expand…
Noise reduction of high pressure plungerpumps and sewer cleaning trucks - new and additional equipped vehicles
Aim of the Projekt was the dissamination of mobil sewer cleaning trucks. Therefore a new noise reduced plungerpump was developed by using a special enclosure which excludes the most important service utilities. Today by using standard components a noise reduced vehicle should show attributes as: truck-motor with acoustical enclosure, noise reduced plunger-pump, watering-pump, internaly cooled with the water of the water tank, flexibel isolation of all pumps and pipeworks from the vehicle, motorspeed less than 900min-1. A total noise reduction of about 6-8 dB(A) can be reached (further information in German).
Expand…
In a zinc smelting works a smelting reactor procedure was applied for the processing of low-zinc containing materials, in order to be able to reuse these residual substances. Zinc and lead were evaporated as reducing agents by means of carbon, enriched in an oxidic filter dust (mixing oxide) and reused for extractive metallurgy. From the remaining components a slag was melted and sold in solid or lumpy form as building material in the hydraulic engineering. Electricity was generated from the process heat and supplied to the work net. The emissions (dust, organic, and inorganic compounds) from the filtering unit were below the authorized values.
Expand…
The low frequency emission of the vacuum pump-extraction system of 2 paper machines was to reduce durably by the application of silencers with new developed membrane absorbers of fine steel, so that an emission gauge of <35 dB(A) could be kept in the night in emission regions situated more than 1 km away. Without silencers, exceedings of this limit were caused by the low frequency tonal components in the third-octave spectrum of 80 Hz. The installed membrane absorber silencers are indifferent to pollution and reconciled with the low frequencies. After 4 years application in paper machine 1 and 1 year in paper machine 3 their effectiveness has been proved. As the damping was more than 15 dB in the third-octave spectrum of 80 Hz, the sound emission could be reduced to below 26 dB(A) at 80 Hz in more than 0.7 km remote emission regions (further information in German).
Expand…
