ITS made its contribution to the fight against noise of an industrial facility in the Middle East, in the context of the conversion of a coal-fired thermal power plant to a gas power plant for the production of electricity (with a power of the order of 1.2 GigaWatt for this combined cycle facility with Heat Recovery Steam Generator - HRSG -). For the phase of works covered by this post, it was - with a view to protecting against excessive sound levels site personnel (e.g. working on supervision, maintenance) and to protect the neighborhood from any sound nuisance - to soundproof a combustion turbine and a generator by combining different techniques and means in terms of sound insulation.
Techniques and means for fighting against noise of an industrial facility
In such a case, the techniques and means for fighting against noise of industrial facilty are namely relating to:
- soundproofing "at source" i.e. the reduction of the sound power level (generally expressed in dB ref. 1 pW) (which is an intrinsic characteristic) of noisy equipment with (in the case of the hardware mentioned above) soundproofed buildings with a powerful ventilation system to evacuate the thermal power of the enclosed equipment and prevent them from overheating; silencers make it possible to reduce the transmission of noise trough openings (air inlets and outlets equipped with fans which are also noisy, and must therefore also be soundproofed) as they make it possible in other contexts to deal with the noise of gaseous vents (e.g. discharges of pressurized fluids into the atmosphere), or ends of aeraulic networks e.g. exhaust lines, chimneys of various processes. This technique was used to soundproof the combustion turbine.
- limiting the propagation of noise by means of screens (noise barrier walls), which allow a reduction in the sound pressure level (generally expressed in dB ref. 20 μPa) which varies with frequency, depending on the distances from the screen of noise source and of the observation point, the dimensions of the noise barrier, and which is influenced by the possible presence of reflective surfaces at the start or finish of the path of the sound waves. This means of combating noise was used to soundproof the alternator (generator).
The technical scope to be considered for such works for fight against noise of an industrial facility includes in particular:
- structural engineering: calculations of sub-assemblies of very large metal constructions, which must withstand bad weather, seismic risks and must authorize the dismantling of some parts of the construction (with large wall areas: walls and roofs) during maintenance or repair work on enclosed equipment
- acoustical design calculations: to allow, in the near acoustic field, sound levels as low as 85 dB(A) at 1 meter (sometimes lower when required) - while some of the noisy equipment has an overall sound power level weighted greater than 135 dB(A), which is considerable - which is made necessary with regard to the problem of health at work as well as that of the tranquility of local residents
- aeraulic studies: regarding air renewal and temperature control inside sounproofing building
- electrical studies: for components such as fans, sensors
As part of this project of fight against noise of the industrial facilty concerned, a metal frame (steel) and:
- for fixed or easily removable parts, by elements: 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 apertures provided for the ventilation of constructions intended for noise lels reduction have been equipped with ventilation silencers:
- as part of the fight against the noise of the combustion turbine by means of a large enclosure (their level of performance must be all the higher as the fans are noisy, which they generally are all the more so as the air flow is large - it depends on the heat output to be evacuated and on the admissible temperature rise, often low when the ambient temperature is high - as in a hot desert - while some of the electrical equipment would not withstand excessively high temperatures)
- as part of the fight against the noise of the generator by means of a noise barrier wall, which is only distinguished from gas turbine ventilated enclosure by the absence of a roof), 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)
This works constituted an additional opportunity for ITS and its commercial partners to demonstrate their mastery of all aspects of an operation to fight against noise of an industrial facility with rigorous multidisciplinary design, harmonious project management and quality construction, meeting the highest level of requirements, delivered within the announced deadlines.
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Structures for fighting againt noise at an industrial facility (a power plant) similar to those covered by this article |
In addition to sound enclosures and noise-barrier walls, ITS markets, for fighting against noise of industrial facilities (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 | |