ITS participated in the noise reduction of a combustion turbine and a generator in a power plant in Southeast Asia, designed for simple cycle operation. With a power greater than 80 Megawatt (80MW), this fzacilty is one of the smallest involving large capacity gas turbines (for some, the unit power can exceed 550 MW in a simple cycle and 800 MW in a combined cycle, which is not is not very far from a nuclear unit and notably allows faster construction and therefore commissioning of the energy production installation, favorably distinguishing this technology on the market).
Design and construction of structures for noise reduction of a combustion turbine and a generator
The design and the construction of structures for the noise reduction of a combustion turbine and a generator constitute recurring activities for ITS and its commercial partners (which also intervene in the context of other various soundproofing projects, particularly in industry), including: to limit the sound emergence of noisy industrial equipment for this energy production plant were carried out in a manner analogous to many other similar projects, within the framework of comparable facilities, with notably:
- structural structural studies: this involves sizing the elements of very large metal constructions to be considered, so that they withstand different stresses e.g. those linked to the site (climatic hazards, seismic risks), those linked to the dismantling of certain sub-assemblies of structures (with large surfaces) during maintenance or repair work on enclosed equipment
- acoustical impact calculations: to obtain, near the walls of structures dedicated to soundproofing, sound levels as low as 85 dB(A) at 1 meter, or even lower in some cases - while some of the noisy equipment have an overall weighted sound power level greater than 135 dB(A), which is considerable - because the following is necessary: :
- protect personnel (e.g. working on supervision, maintenance) of the energy production site (i.e. avoid situations of hearing trauma, accidents when warning signals are not heard); European directive 2003/10/EC stipulates noise exposure limits for this purpose:
- limit exposure values to noise for workers: exposure level L EX, 8h = 87 dB (A) and peak sound pressure ppeak = 200 Pa or 140 dB(C) ref. 20 μPa
- higher exposure values to noise for workers triggering action: exposure level L EX, 8h = 85 dB (A) and peak sound pressure ppeak = 140 Pa or 137 dB(C) ref. 20 μPa
- lower exposure values to noise of worker triggering action: exposure level L EX, 8h = 80 dB (A) and a peak sound pressure ppeak = 112 Pa or 135 dB(C) ref. 20 μPa
- ensure the tranquility of the neighborhood; French regulations distinguish the daytime period (7:00 a.m. to 10:00 p.m. except Sundays and public holidays) and the nighttime period (10:00 p.m. to 7:00 a.m. as well as Sundays and public holidays) and, in some cases, a prefectural decree (when it is not ministerial) sets the noise levels not to be exceeded at the property boundary: this is particularly the case for Facilities Classified for Environmental Protection (FCPEP) e.g. 70 dB(A) during daytime periods and 60 dB(A) during nocturnal. Emergence i.e. the difference between the equivalent A-weighted continuous pressure levels of the ambient noise (facility in operation) and the residual noise (in the absence of the noise generated by the facility, but measured over the operating period of the facilty) is limited in Regulated Emergence Zones (REZ), which generally include, near the facility: homes, building areas and areas occupied by third parties e.g. Public Acces Buildings (PAB), other industrial establishments. If the ambient noise level in the REZ (including power plant noise) is between 35 dB(A) and 45 dB(A) then the admissible emergence is 6 dB(A) during the day and 4 dB (A) during the night. If the ambient noise level in the REZ (including power plant noise) is greater than 45 dB(A) then the admissible emergence is 5 dB(A) during the day and 3 dB(A) during the night . In the case of an Facility Classified for Environmental Protection (FCEP), the marked tone, the presence of which is linked to the difference between the sound pressure level in a given 1/3 octave frequency band and adjacent frequency bands, is considered undesirable if it exceeds 10 dB in the frequency interval 50 Hz-315 Hz or 5 dB in the frequency interval 400 Hz-8000 Hz.
- protect personnel (e.g. working on supervision, maintenance) of the energy production site (i.e. avoid situations of hearing trauma, accidents when warning signals are not heard); European directive 2003/10/EC stipulates noise exposure limits for this purpose:
- aeraulic sizing studies: with regard to air renewal and to evacuation of the (very significant) heat power dissipated inside the sound enclosures
- electrical study: for components such as fans, sensors
It is generally planned (and this was the case in the context of this project to reduce the noise of a combustion turbine and a generator) a (steel) metallic frame and:
- for fixed or easily removable parts, by sub-assemblies: industrial soundproofing panels with an absorbing face (modular)
- for acces for employees and some hardware: (rotating) acoustic doorsets with, for translucent parts (with glazing guaranteeing residual safety in the event of accidental breakage): acoustic window sets
In addition, the openings provided for the ventilation of works intended for noise reduction have been equipped with ventilation silencers (to limit the acoustic power transmitted through the apertures):
- for the noise reduction of the combustion turbine (in a closed space), fans (also: noisy by nature, the silencers having also served to reduce their noise impact) were provided to force the evacuation of hot air
- for the nosie reduction of the generator (by means of a noise-barrier wall), a principle of ventilation by natural convection was used (with air intakes in the lower part of the structure, and an evacuation by the top)
The sound enclosure of the combustion turbine and the noise barrier wall for the generator were built in accordance with the highest quality standards (selection of first-class raw materials and components, careful welding and assembly work, anti-corrosion maximum protection, optimized fixings and connections between subsets, rigorous control and careful packaging in sea containers); exhaustive, precise and unambiguous documentation has been prepared to allow successful installation on site the first time, even by labor of an ordinary technical level, made available by the Customer).
Recognized for their design and manufacturing quality, their performance and their durability (like all noise reduction equipment marketed by ITS), the combustion turbine sound enclosure and the generator noise barrier wall discussed in this article constitutes the ultimate.
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Structures for the noise reduction of combustion (gas) turbines and generators in a power plant similar to those covered by this article |
In addition to sound enclosures and noise-barrier walls, ITS markets, for noise reduction in power plants (visible in the photo opposite but not delivered as part of the project subject of this article) soundproofed air intake systems for combustion turbines / gas turbines, exhaust silencers for combustion turbines / gas turbines, and also Vent silencers for pressurized gas | |