Processes related to aluminum processing (e.g. the melting activity or the electrolysis methods for this material) require a lot of energy: a power plant based on the use of turbomachinery can constitute a solution to allow a self-sufficiency with very high levels of operational flexibility (and with very high efficiency).
But then care must be taken to provide appropriate soundproofing means, on the one hand to allow acceptable working conditions for personnel ensuring the operation and maintenance of the various production equipment with respect to noise and on the other hand for the prevention of any surrounding noise disturbance (for the neighborhood).
In fact, turbomachines (whether they are gas turbines or steam turbines) have very high noise emissions (the sound power level of many subassemblies exceeds 130 dBA with a sound spectrum rich in low frequencies such as in medium-high frequencies) which must be the subject of a specific treatment, being cumulated in the case of combined cycle installations (alternators are not left behind).
The air intake of combustion turbines is a major source of noise, for which gigantic soundproofing devices must be considered (the area of their inlet section, which is impacted by the considerations in relation to filtration of air, sucked with colossal flow, can exceed 100 m2).
The exhaust of gas turbines is also a very powerful sound source that must be treated to limit the spread of noise:
- in the case of a simple cycle installation: at the outlet of the (single) stack, installed downstream of the turbine
- in the case of a combined cycle installation: not only at the outlet of the stack, installed downstream of the turbine, by means of a three-way register (the english wording “diverter” has no equivalence in french, the term "bypass" is often abandoned in favor of anglicism "by-pass" to designate this stack), but also at the outlet of the chimney located downstream of a boiler or Heat Recovery Steam Generator (HRSG)
ITS can be solicited in connection with the study (which then involves complex calculations in the fields of fluid mechanics and of acoustics, often by finite element methods), construction - and if necessary, installation - of such high-tech equipment, which is not always provided by the Original Parts Manufacturer in the case of a turbine manufacturer, which is then the responsibility of an Engineering, Procurement and Construction (EPC) contractor, when it is not supplied by the End Customer himself.
ITS has participated in the soundproofing of turbomachinery for a combined-cycle power plant located in a processing unit for aluminum ore in the Middle East (in the Persian Gulf).
With respect to those turbomachines i.e. 3 combined cycle combustion turbines (thus with steam turbines and associated generators, with a total output of the order of 2000 MW), it was necessary to achieve the acoustic insulation (soundproofing) of turbomachines and auxiliary equipment (they are numerous for such installations) in a position of radiating (casing) noise and which therefore had to be installed inside buildings limiting the transmission of sounds towards outside.
As always in such circumstances, it was necessary to equip the latter with specific ventilation systems to control the rise in temperature due to heat exchange (convection and radiation), by the means of fans (it should be noted that these are sometimes installed in an explosive atmosphere, which then requires special equipment) being themselves noisy, which complicates the soundproofing action of enclosed noise sources; unless an acoustic screen is sufficient if it only comes to the protection of particular areas of the installations, in the near acoustic field, exclusively with a view to limiting the exposure of workers to noise, which is rarely the case.
And of course, it was necessary to limit the amplification of sound levels on the noise source side by using absorbent panels (able to limit the reverberation due to the reflections of sound waves on the partitions - walls and roofs - when it came to confined spaces like buildings or housings. The design and construction of the soundproofing equipment (dismountable metallic soundproofing panels installed on a metallic frame that constitutes buildings and noise barrier walls, ventilation systems with noise reduction devices) constituted, in connection with these turbomachines, the scope of supply considered in the context of this project.