The design of soundproofing devices for subsets of a gas turbine of high power output is an acoustic engineering work that is frequently required on the occasion of the construction of a power generation plant, when it comes to take into account, properly, the noise emissions related to such an installation.
Indeed, in a power plant with gas turbines (combustion turbines), some airborne noise is emitted by the various subsets making up each turbomachinery (in addition to noise emissions associated with the mouths for air intake and exhaust not included in the current project, although regularly studied and subject of simulation and design work by ITS as part of other projects in the field of energy production):
- the turbine compartment i.e. compressors, combustion chamber, turbine
- the auxiliary compartment
- the load compartment
- the portion of the envelope of the intake duct enclosed
- the portion of the envelope of the exhaust duct enclosed
- related equipments
This noise is so powerful that it is potentially causing noise pollution for personnel of the operator operating in the vicinity as for the neighborhood (including long distance). It is often necessary to use in such cases a soundproofing equipment of high technology to ensure compliance of the installation of one hand with respect to the legislation on noise at work and on the other hand with respect to the regulation in terms of environmental protection.
ITS will participate in the design of soundproofing devices for 3 sub sets of a gas turbine with high power output (more than 120 MW for simple cycle, more than 190 MW for combined cycle) for a power generation unit.
This soundproofing equipment will have a sound reduction particularly important (the overall sound power level to be considered is greater than 135 dBA for one of the sub sets and noise emissions are with a very wide frequency spectrum), requiring a specific design of the partitions and of the ventilation system which is one of the major features of the soundproofing equipment.
The optimization of the cost and of the duration of intervention for assembly and disassembly operations are key factors of success of the efficient soundproofing concept considered.
The simulation of the sound attenuation of partitions, of the insertion loss (with and without flow noise) and of the total pressure loss of ventilation silencers as well as the simulation of the impact after soundproofing on the one hand in terms of sound power level and on the other hand in terms of sound pressure level at specified positions was performed using the software SILDIS (cf. acoustics simulation software).
Indeed, the software developed by the human resource of ITS allows the simulation of the acoustic and aeraulic performances of silencers (including: those with discontinuous splitters cf. Modules 1 and 1A). And it also allows the computation of the performance of plane partitions and of duct walls (cf. Modules 2 and 3), the prediction of the acoustic performance of straight ducts (cf. Module 4), the prediction of break-out noise, namely in case of ducts of variable section (Modules 5 and 5A), the prediction of the acoustic performance of the bends (Module 6), the prediction of nozzle reflection (Module 7), the prediction of the sound impact of duct systems (Module 8).
The performed calculations make it possible to predict and compare the performance of the various components of the proposed construction, so as to select those that are most appropriate for solving a given problem related to noise, when it comes to ensure sound emissions in accordance with a specification or with a regulatory limit.
Specific materials and construction systems to meet ambitious and varied targets in terms of technical performance will be integrated into the design as required.
Related features such as weather resistance, disassembly of the whole and of subsets, securities, lighting, electrical works ... will be integrated according to the needs for the soundprrofing of those gas turbine sub sets.
In addition, the course of this project shows - once again - the possibilities for design and optimization of soundproofing equipment of the software SILDIS, whose computing power and reliability, as well as whose versatility made of it a choice tool for the selection of products and construction systems for many projects of sound insulation.