Sound enclosures for gas turbines (November 2016)

Energy production based on the use of gas turbines (in single cycle or in combined cycle), is widely used in countries without a highly developed nuclear power plant fleet.

Such power stations make possible to have large production capacities within a relatively short period of time in order to satisfy the growing needs of the populations.

In many cases, these facilities base the very existence of the electrical network of regions or countries.

In other cases, gas-fired power stations are used to manage electricity consumption peaks when other modes of production, even at full capacity, are temporarily insufficient in view of increased demand e.g. due to exceptional circumstances.

Such installations involve very powerful thermodynamic rotating machine using fossil fuels being in particular gaseous (e.g. natural gas) or liquids (e.g. fuel oil, crude oil) whose noise emissions are very high and require means of preventing nuisance for the personnel of the power plant as for its neighbors.

ITS will participate in the construction of sound enclosures for two high-power gas turbines (more than 120 MW in single cycle, more than 190 MW in combined cycle) for a power plant in the Middle East.

The overall acoustic performance of these soundproofing equipment will be due to their ability to prevent the propagation of noise - very important in terms of sound power level: typically 135 dB (A) and very broad in terms of frequency spectrum: typically 20 to 20 kHz - towards the outside of the power plant, not only through its wall and roof, but also through the components of the sophisticated ventilation systems required for proper operation.

The modalities of assembly and dismantling / reassembly of these equipments will be functionalities significantly impacting their quality and their durability, taking into account the site data (e.g. climatic conditions, seismic risks) and local building codes superimposing on international rules and standards being  otherwise all important challenges for such a project.

Filtration systems for gas turbines (December 2016)

Gas turbines are a mode of production of electric power, privileged over others for variables reasons depending on the case, including sometimes the fact that it involves power stations of which footprint is moderate (when compared to the footprint of coal-fired plants or of nuclear power stations), which can be therefore a priori implanted almost everywhere and whose location can be notably guided by the proximity of consumers (e.g. in industrial zones when it is not in a semi-urban environment) or by the proximity of fuel deposits (e.g. gas, crude oil).

The fight against noise pollution that they may generate is not the only field of intervention of ITS.

Indeed, these plants with very variable production capacity (from a few MW for the smallest ones to several hundred MW for the largest ones) are based on the use of machine affiliated to internal combustion engine requiring combustion air and a fluid for its (complex) forced ventilation systems sufficiently clean.

In case of plants which are sometimes located in places as hostile as a desert where recurring sandstorms occur, specific devices must be envisaged in order to allow the proper functioning and durability of the various high-tech equipment involved by the various operating principles used.

ITS will participate in the construction of filtration systems for two high-power gas turbines (more than 120 MW single cycle, more than 190 MW combined cycle) for a power plant in North Africa.

The quality of the air once filtered will obviously constitute a major criterion of judgment of the quality of these systems, the modalities of their maintenance (e.g. the replacement of the consumables) also constituting an essential aspect.

As often happens for installations upgrading projects providing the implementation a posteriori of equipment not originally planned, the design of devices which are both efficient and compatible with the existing equipment e.g. sufficiently compact to enable their addition in a gas turbine environment where little space is available for them will be a major challenge.

As always in regard to gas turbines filtration, the choice of optimum filter media and their integration in a sophisticated system whose piloting requires specific instrumentation will be key factors for success.

Soundproofing works in a power plant (February 2017)

Gas-fired power plants are based on the use of combustion turbines whose noise emissions (as well as those of their ancillary equipment) are very important: they should be maintained at an acceptable level for the neighborhood as well as for the employees operating within the perimeter of the plant.

Among the most notable sources of noise, mention may be made of the turbine itself, of course, but also of the gas module, of the injection module or even of sets of duct surfaces, in particular in the upstream part of the exhaust system, where the sound emissions are not attenuated by a silencer.

In such cases, it is necessary to design and construct soundproofed buildings to limit noise diffusion, with ventilation systems being appropriate to the evacuation of the calorific energy dissipated by the various organs.

ITS will be involved in soundproofing works in a power plant whose production is based on the use of a high-power gas turbine (more than 120 MW in single cycle, over 190 MW in combined cycle) in western Africa.

The goal of the project will be to not exceed the limits for exposure to noise, namely in relation to a sound power level for the turbine of the order of 135 dB (A), which is very wide in terms of frequency spectrum (typically 20 to 20 kHz).

International rules and standards will be applied for the design and construction of the considered buildings, for which removable sub-assemblies, sometimes of large dimensions, will have to be provided for the maintenance operations of the various enclosed hardware.

Improving the acoustics of a meeting room (January 2017)

A meeting room is a space for which the objective in terms of acoustics is to offer to the participants (actors or spectators of the meeting) a comfort for speech and listening during an extended period of time even though, (especially in the frequency range 500-2000 Hz), the speech intelligibility may be insufficient due to inappropriate quality of the construction (sometimes: although the premises are recent and therefore supposed to take into account the auditory well-being of the occupants as it should be self-evident nowadays). 

For a meeting room, such a symptom of a lack of acoustic comfort frequently causing recriminations can (often) be directly related to an excessive reverberation of the considered space and (thus) require remedial actions. 

Indeed, the results of the reverberation time measurements carried out in such cases often indicate that the internal acoustics of the space under consideration are perfectible, notwithstanding the absence of specific regulations applicable in this case. 

ITS will contribute to improve the acoustic comfort of a meeting room (capable of accommodating up to 120 people), near Lyon (Rhône-Alpes region, France) in relation to a situation involving existing office premises (yet new) that one might consider (at least for some of them), unsuitable for their use since they are perfectly devoid of materials capable of absorbing sounds. 

The improvement of the acoustic performance (in relation to its duration of reverberation) of what is for the time being a very reverberant ready-to-fit platform will imply the use of absorbent acoustic linings for some wall and for the roof (the considered space is located on the top floor of an office building) carefully selected for their acoustical properties. 

On the one hand, the design of the installations aiming at increasing auditory comfort, based on a distribution of the absorbent materials and on installation systems harmonized with the existing architectural choice (i.e. the enhancement of the metal elements of building structure and envelope) and on the other hand the selection of colors particularly becoming and luminous will contribute - no doubt - to obtain a meeting room keeping all promises, i.e. where it will be good to meet to inquire, to share information and even to debate in a constructive way as it should in a professional context.

Soundproofing of a company restaurant (April 2017)

Whether it is a pleasure meal in a friendly or family context, or whether it is to regain strength and take a break, e.g. in a working context, a moment spent in a restaurant does not deliver all its promises if the acoustic environment is not up to par.

Indeed, if such a place has not been the subject of sufficient precautions with regard to the problems of soundproofing, a sound overbid occurs there often, which is due to the fact that each raises the voice to try to be heard, what contributes to the increase of hubbub - this phenomenon being sometimes called "cocktail effect" -.

The best table from a culinary point of view, which in some cases could be worth a detour or even deserve a trip in relation to the contents of the plates and the quality of the service - which can be a pleasure for the eyes, the nose and the mouth - can then be turn into a place which must be avoided, in view of the discomfort furthermore experienced by the ears.

And what about company restaurant,  which are not always distinguished by the quality of the menus, but in which one of the main objectives is to take a break (in which the social dimension of discussions between co-workers must have all its place) if one can not ear each other among neighbors of tables ?

Obviously, the acoustic comfort of gourmet restaurant or simple cafeterias is still too often neglected, even though it contributes to the general appreciation of the guests about the moment they have spent and thus about the quality of the place.

ITS will participate in the soundproofing of a company restaurant near Lyon, France, in the Rhône-Alpes region.

Absorbent materials have been carefully selected for their acoustic performance i.e. their ability to absorb sounds as well as for their decorative contribution in harmony with what exists.

They will be installed at the level of the wall and ceiling of a dining room located on the ground floor, as well as under the roof of a dining room located on the first floor, so as to control their reverberation which constitutes a fundamental parameter of the acoustic quality of such spaces.

If it is not certain that the frequentation of this cafeteria will be due to a quest for culinary excellence, at least it will offer to employees a quiet place to eat and maybe even if they look at the cloud-like absorbent linings above their heads, to escape for a few moments, of what one must admit the preciousness in our modern world.

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