Noise protection in the boiler room. Noise reduction measures

Date: 12/12/2015

Boilers make a lot of noise. They have many elements that make sounds: these are pumps, fans, pumps and other mechanisms. In principle, work in industry, with industrial equipment, one way or another forces a specialist to deal with noise, and there is no way to make the units completely silent yet. But you can make them pretty much less loud.

How to reduce the noise of the boiler room when designing

Very strict requirements are imposed on the noise level of electric and thermal power facilities, especially if the designated facilities are located within the city. A boiler room is just an object of heat power engineering, and even being compact, it can cause significant discomfort to others.

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Russian Ministry of Health

Moscow

1. Developed by the Research Institute of Occupational Medicine Russian Academy Sciences (Suvorov G.A., Shkarinov L.N., Prokopenko L.V., Kravchenko O.K.), Moscow Research Institute of Hygiene. F.F. Erisman (Karagodina I.L., Smirnova T.G.).

2. Approved and put into effect by the Decree of the State Committee for Sanitary and Epidemiological Supervision of Russia dated October 31, 1996 N 36.

3. Introduced instead of "Sanitary norms for permissible noise levels at workplaces" N 3223-85, "Sanitary norms for permissible noise in residential and public buildings and on the territory of residential development" N 3077-84, "Hygienic recommendations for establishing noise levels at workers places, taking into account the intensity and severity of labor "N 2411-81.

APPROVED
Decree of the State Committee for Sanitary and Epidemiological Supervision
Russia dated October 31, 1996 N 36
Date of introduction since approval

1. Scope and general provisions

1.1. These sanitary norms establish the classification of noise; normalized parameters and maximum permissible noise levels at workplaces, permissible noise levels in the premises of residential, public buildings and in residential areas.

1.2. Sanitary standards are mandatory for all organizations and legal entities in the territory Russian Federation regardless of the form of ownership, subordination and affiliation and individuals regardless of citizenship.

1.3. References and the requirements of sanitary standards must be taken into account in State standards and in all normative and technical documents regulating planning, design, technological, certification, operational requirements for production facilities, residential, public buildings, technological, engineering, sanitary equipment and machines, vehicles, household appliances.

1.4. Responsibility for fulfilling the requirements of the Sanitary Norms is assigned in the manner prescribed by law to the heads and officials of enterprises, institutions and organizations, as well as citizens.

1.5. Control over the implementation of the Sanitary Standards is carried out by the bodies and institutions of the State Sanitary and Epidemiological Supervision of Russia in accordance with the Law of the RSFSR "On the Sanitary and Epidemiological Welfare of the Population" dated April 19, 1991 and taking into account the requirements of the current sanitary rules and norms.

1.6. Measurement and hygienic assessment of noise, as well as preventive measures should be carried out in accordance with the guideline 2.2.4 / 2.1.8-96 "Hygienic assessment of the physical factors of the production and environment" (under approval).

1.7. With the approval of these sanitary standards, the “Sanitary standards for permissible noise levels at workplaces” N 3223-85, “Sanitary standards for permissible noise in the premises of residential and public buildings and on the territory of residential development” N 3077-84, “Hygienic recommendations for setting levels noise at workplaces, taking into account the intensity and severity of labor "N 2411-81.

2.1. Law of the RSFSR "On the sanitary and epidemiological well-being of the population" dated 19.04.91.

2.2. Law of the Russian Federation "On Environmental Protection" dated 12/19/91.

2.3. Law of the Russian Federation "On Protection of Consumer Rights" dated 07.02.92.

2.4. Law of the Russian Federation "On certification of products and services" dated 10.06.93.

2.5. "Regulations on the procedure for the development, approval, publication, implementation of federal, republican and local sanitary rules, as well as on the procedure for the operation of all-Union sanitary rules on the territory of the RSFSR", approved by Resolution of the Council of Ministers of the RSFSR of 01.07.91 N 375.

2.6. Decree of the State Committee for Sanitary and Epidemiological Supervision of Russia "Regulations on the procedure for issuing hygienic certificates for products" dated 05.01.93 N 1.

3. Terms and definitions

3.1. Sound pressure is a variable component of air or gas pressure resulting from sound vibrations, Pa.

3.2. Equivalent / energy / sound level, LA.eq., dBA, intermittent noise - the sound level of constant broadband noise, which has the same RMS sound pressure as this intermittent noise for a certain period of time.

3.3. The maximum permissible level (MPL) of noise is the level of a factor that, during daily (except weekends) work, but not more than 40 hours a week during the entire working experience, should not cause diseases or deviations in the state of health detected modern methods research in the process of work or in the remote periods of life of the present and subsequent generations. Compliance with the noise limit does not exclude health problems in hypersensitive individuals.

3.4. The permissible noise level is the level that does not cause significant concern to a person and significant changes in the indicators of the functional state of noise-sensitive systems and analyzers.

3.5. Maximum sound level, LА.max., dBA - the sound level corresponding to the maximum indicator of a measuring, direct-reading instrument (sound level meter) during visual reading, or the sound level value exceeded for 1% of the measurement time during registration by an automatic device.

4. Classification of noise affecting a person

4.1. According to the nature of the noise spectrum, there are:

• broadband noise with a continuous spectrum more than 1 octave wide;
• tonal noise, in the spectrum of which there are pronounced tones. The tonal nature of the noise for practical purposes is established by measuring in 1/3 octave frequency bands by exceeding the level in one band over the neighboring ones by at least 10 dB.

4.2. According to the temporal characteristics of noise, there are:

• constant noise, the sound level of which during an 8-hour working day or during the measurement time in the premises of residential and public buildings, on the territory of residential development changes in time by no more than 5 dBA when measured on the time characteristic of the sound level meter “slowly”;
• intermittent noise, the level of which during an 8-hour working day, work shift or during measurements in the premises of residential and public buildings, on the territory of residential development changes over time by more than 5 dBA when measured on the time characteristic of the sound level meter "slowly".

4.3. Intermittent noises are divided into:

• time-varying noise, the sound level of which changes continuously over time;
• intermittent noise, the sound level of which changes stepwise (by 5 dBA or more), and the duration of the intervals during which the level remains constant is 1 s or more;
• impulse noise consisting of one or more audio signals, each of less than 1 s duration, while the sound levels in dBAI and dBA, measured respectively on the “impulse” and “slow” time characteristics, differ by at least 7 dB.

5. Normalized parameters and maximum permissible noise levels at workplaces

5.1. Characteristics of constant noise at workplaces are sound pressure levels in dB in octave bands with geometric mean frequencies of 31.5; 63; 125; 250; 500; 1000; 2000; 4000; 8000 Hz, determined by the formula:

Where P is the root mean square value of sound pressure, Pa;
P0 is the initial value of the sound pressure in the air equal to 2 10-5Pa.

5.1.1. It is allowed to take as a characteristic of constant broadband noise at workplaces the sound level in dBA, measured on the “slow” time characteristic of the sound level meter, determined by the formula:

Where RA is the root mean square value of the sound pressure, taking into account the correction "A" of the sound level meter, Pa.

5.2. A characteristic of intermittent noise at workplaces is the equivalent (in terms of energy) sound level in dBA.

5.3. Maximum permissible sound levels and equivalent sound levels at workplaces, taking into account the intensity and severity of labor activity.

A quantitative assessment of the severity and intensity of the labor process should be carried out in accordance with Guideline 2.2.013-94 "Hygienic criteria for assessing working conditions in terms of harmfulness and danger of factors in the working environment, severity, intensity of the labor process."

6. Rated parameters and permissible noise levels in the premises of residential, public buildings and residential areas

6.1. Normalized constant noise parameters are sound pressure levels L, dB, in octave bands with geometric mean frequencies: 31.5; 63; 125; 250; 500; 1000; 2000; 4000; 8000 Hz. For an approximate assessment, it is allowed to use sound levels LA, dBA.

6.2. The normalized parameters of intermittent noise are equivalent (in terms of energy) sound levels LAeq, dBA, and maximum sound levels LAmax, dBA.

Evaluation of non-permanent noise for compliance with permissible levels should be carried out simultaneously on the equivalent and maximum sound levels. Exceeding one of the indicators should be considered as non-compliance with these sanitary standards.

6.3. Permissible values ​​of sound pressure levels in octave frequency bands, equivalent and maximum sound levels of penetrating noise in the premises of residential and public buildings and noise in residential areas.

Bibliography

• Guideline 2.2.4 / 2.1.8.000-95 "Hygienic assessment of the physical factors of the production and environment."
• Guideline 2.2.013-94 "Hygienic criteria for assessing working conditions in terms of harmfulness and danger of factors in the working environment, severity, intensity of the labor process."
• Suvorov G. A., Denisov E. I., Shkarinov L. N. Hygienic regulation of industrial noise and vibrations. — M.: Medicine, 1984. — 240 p.
• Suvorov G. A., Prokopenko L. V., Yakimova L. D. Noise and health (environmental and hygienic problems). - M: Soyuz, 1996. - 150 p.
• Permissible levels of noise, vibration and sound insulation requirements in residential and public buildings. MGSN 2.04.97 (Moscow city building codes). - M., 1997. - 37 p.

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• Obtaining technical specifications (TU) for the following types of work: gasification of the facility, water supply, electricity supply, sewerage. And also - all permits for boiler plants in the SES, the Fire Service and other organizations. Gas limits - preparation of documentation, receipt.
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Advantages:

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Boiler houses are designed and installed in accordance with a number of rules, for example:

• GOST 21.606-95 SPDS "Rules for the implementation of working documentation for thermal mechanical solutions for boiler rooms"
• GOST 21563-93 Hot water boilers. Main parameters and technical requirements
• PU and BE "Rules for the design and safe operation of steam boilers"
• PB 12-529-03 "Safety Rules for Gas Distribution and Gas Consumption Systems".

If you have a task to get a valid object back to top heating season we offer you the option "Block-modular boiler house" based on standard solutions. Modular boiler houses supplied under this program have the following advantages: a) the use of a standard project reduces the time for designing and coordinating the project, b) it becomes possible to purchase the main equipment in parallel with the development of individual parts of the project.

We also translate steam boilers in hot water mode. With this operation steam boilers lose from the rated power, while solving certain heating problems. These are solutions mainly for Russian boilers. The advantage of this operation is that existing steam boilers do not have to be replaced with new ones, which can be beneficial in the short term from an economic point of view.

All supplied boiler equipment is certified and has permissions for use on the territory of the Russian Federation - gas boilers, heating boilers, burners, heat exchangers, valves etc. The specified documentation is included in the scope of delivery.

The number of appeals of citizens entering the Office of Rospotrebnadzor Tyumen region, about the deterioration of living conditions due to the impact of excess noise levels increases annually.

In 2013, 362 appeals were received (in total for violations of peace and quiet, accommodation and noise), in 2014 - 416 appeals, in 2015 80 appeals have already been received.

According to the established practice, after the request of residents, the Department appoints measurements of noise and vibration levels in a residential building. If necessary, measurements are carried out in organizations located near apartments, where, for example, “noisy” equipment is operated - a source of noise (restaurant, cafe, shop, etc.). If noise and vibration levels are found to exceed the permissible values, in accordance with SN 2.2.4/2.1.8.562-96 "Noise at workplaces, in residential, public buildings and on the territory of residential development", to the owners of noise sources - legal entities, individual entrepreneurs - the Department issues an order to eliminate the identified violations of sanitary legislation.

How can the noise from the equipment listed above be reduced so that there are no complaints from the residents of the house during its operation? Certainly, perfect option- to provide for the necessary measures at the design stage of a residential building, then the development of noise reduction measures is always possible, and their implementation during construction is ten times cheaper than in those houses that have already been built.

The situation is quite different if the building has already been built and there are noise sources in it that exceed the current standards. Then, most often, noisy units are replaced with less noisy ones and measures are taken to isolate the units and the communications leading to them. Next, we will look at specific sources of noise and vibration isolation measures for equipment.

NOISE FROM THE AIR CONDITIONER

The use of three-link vibration isolation, when the air conditioner is installed on the frame through a vibration isolator, and the frame - on a reinforced concrete slab through rubber gaskets (in this case, the reinforced concrete slab is installed on spring vibration isolators on the roof of the building), leads to a decrease in penetrating structural noise to levels permissible in residential premises.

To reduce noise, in addition to strengthening the noise and vibration isolation of the air duct walls and installing a silencer on the air duct of the ventilation unit (from the side of the premises), it is necessary to fasten the expansion chamber and air ducts to the ceiling through vibration isolating hangers or gaskets.

NOISE FROM THE BOILER ROOM ON THE ROOF

To protect against the noise of the boiler house located on the roof of the house, foundation slab the roof boiler house is installed on spring vibration isolators or a vibration isolating mat made of a special material. The pumps and boiler units equipped in the boiler room are installed on vibration isolators and soft inserts are used.

The pumps in the boiler room must not be placed with the motor downwards! They must be mounted in such a way that the load from the pipelines is not transferred to the pump casing. In addition, the noise level is higher with a higher power pump or if several pumps are installed. To reduce noise, the foundation plate of the boiler room can also be placed on spring dampers or high-strength multilayer rubber and rubber-metal vibration isolators.

The current regulations do not allow the placement of a roof boiler directly on the ceiling of residential premises (the ceiling of a residential premises cannot serve as the base of the boiler room floor), as well as adjacent to residential premises. It is not allowed to design roof boiler houses on the buildings of preschool and school institutions, medical buildings of polyclinics and hospitals with round-the-clock stay of patients, on the sleeping buildings of sanatoriums and recreation facilities. When installing equipment on roofs and ceilings, it is desirable to place it in places farthest from the protected objects.

NOISE FROM INTERNET EQUIPMENT

According to the recommendations for the design of communication systems, informatization and dispatching of housing construction objects, it is recommended to install cellular antenna amplifiers in a metal cabinet with a locking device on technical floors, attics or stairwells of upper floors. If it is necessary to install house amplifiers on different floors multi-storey buildings they should be installed in metal cabinets in close proximity to the riser under the ceiling, usually at a height of at least 2 m from the bottom of the cabinet to the floor.

When installing amplifiers on technical floors and attics, to eliminate the transmission of vibration of a metal cabinet with a locking device, the latter must be installed on vibration isolators.

OUTPUT - VIBRATION ISOLATORS AND FLOATING FLOORS

For ventilation, refrigeration equipment on the upper, lower and intermediate technical floors of residential buildings, hotels, multifunctional complexes or in the vicinity of noise-rated rooms where people constantly stay, you can install the units on factory vibration isolators on a reinforced concrete slab. This slab is mounted on a vibration-isolated layer or springs on a "floating" floor (an additional reinforced concrete slab on a vibration-isolation layer) in a technical room. It should be noted that fans, outdoor condensing units, which are now produced, are equipped with vibration isolators only at the request of the customer.

"Floating" floors without special vibration isolators can only be used with equipment that has an operating frequency of more than 45-50 Hz. This is usually small cars vibration isolation of which can be provided in other ways. The efficiency of floors on an elastic foundation at such low frequencies is low, therefore they are used exclusively in combination with other types of vibration isolators, which provides high vibration isolation at low frequencies (due to vibration isolators), as well as at medium and high frequencies (due to vibration isolators and a “floating” floor). ).

The floating floor screed must be carefully isolated from the walls and the supporting floor slab, since the formation of even small rigid bridges between them can significantly impair its vibration isolation properties. In places where the "floating" floor adjoins the walls, there must be a seam made of non-hardening materials that does not allow water to pass through.

NOISE FROM THE GARBAGE DUCT

To reduce noise, it is necessary to comply with the requirements of the norms and not design the trunk of the garbage chute adjacent to residential premises. The trunk of the garbage chute should not adjoin or be located in the walls enclosing residential or service premises with normalized noise levels.

The most common measures to reduce noise from garbage chutes are as follows:

• in the premises for collecting garbage, a “floating” floor is provided;
• with the consent of the residents of all apartments in the entrance, the garbage chute is welded (or liquidated) with the placement of wheelchair garbage chambers, concierge rooms, etc. in the room. (the positive point is that in addition to noise, odors disappear, the possibility of rats and insects, the likelihood of fires, dirt, etc. is eliminated);
• the loading valve bucket is mounted with framed rubber or magnetic seals;
• decorative heat and noise protective lining of the trunk of the garbage chute made of building materials is separated from the building structures of the building with soundproof gaskets.

Today, many construction companies offer their services, various designs to increase the sound insulation of the walls and promise complete silence. It should be noted that in fact, no structures can remove structural noise transmitted through the floors, ceilings and walls when dumping municipal solid waste into the garbage chute.

NOISE FROM ELEVATORS

In SP 51.13330.2011 “Noise protection. Updated edition of SNiP 23-03-2003 "it is said that it is advisable to place elevator shafts in the stairwell between flights of stairs(clause 11.8). In the architectural and planning solution of a residential building, it should be provided that the built-in elevator shaft adjoins premises that do not require increased protection against noise and vibration (halls, corridors, kitchens, sanitary facilities). All elevator shafts, regardless of the planning solution, must be self-supporting and have an independent foundation.

Shafts should be separated from other building structures with an acoustic joint of 40-50 mm or vibration-isolating pads. As the material of the elastic layer, slabs of acoustic mineral wool on a basalt or fiberglass base and various foamed polymeric roll materials are recommended.

To protect against structural noise of an elevator installation, its drive motor with a gearbox and a winch, usually mounted on one common frame, is vibration isolated from the supporting surface. Modern elevator drive units are equipped with appropriate vibration isolators installed under metal frames, on which motors, gearboxes and winches are rigidly mounted, and therefore additional vibration isolation of the drive unit is usually not required. At the same time, it is additionally recommended to make a two-stage (two-link) vibration isolation system by installing the support frame through vibration isolators on a reinforced concrete slab, which is also separated from the floor by vibration isolators.

The operation of lift winches installed on two-stage vibration isolation systems showed that the noise levels from them do not exceed the standard values ​​in the nearest residential premises (through 1-2 walls). For practical purposes, care must be taken to ensure that vibration isolation is not disturbed by random rigid bridges between the metal frame and the supporting surface. The supply cables must have sufficiently long flexible loops. However, the operation of other elements of elevator installations (control panels, transformers, car and counterweight shoes, etc.) may be accompanied by noise above the normative values.

It is forbidden to design the floor of the elevator engine room as a continuation of the floor slab of the ceiling of the living room of the upper floor.

NOISE FROM TRANSFORMERSUBSTATIONSON THE GROUND FLOOR

To protect against noise transformer substations of residential and other premises with standardized noise levels, the following conditions must be observed:

• premises of built-in transformer substations;
• should not be adjacent to noise-protected rooms;
• built-in transformer substations should
• located in basements or on the first floors of buildings;
• transformers must be installed on vibration isolators designed in an appropriate way;
• electrical panels, containing electromagnetic communication devices, and separately installed oil switches with an electric drive must be mounted on rubber vibration isolators (air disconnectors do not require vibration isolation);
• ventilation devices of the premises of built-in transformer substations must be equipped with noise suppressors.

To further reduce noise from the built-in transformer substation, it is advisable to process its ceilings and internal walls sound absorbing lining.

In built-in transformer substations, protection against electromagnetic radiation must be made (a grid of special material with grounding to reduce the level of radiation of the electrical component and a steel sheet for magnetic).

NOISE FROM ATTACHED BOILERS,BASEMENT PUMPS AND PIPES

Boiler room equipment (pumps and pipelines, ventilation units, air ducts, gas boilers, etc.) must be vibration-isolated using vibration foundations and soft inserts. Ventilation units are equipped with silencers.

In order to isolate the pumps located in the basements, elevator units in individual heating points (ITP), ventilation units, refrigeration chambers, the specified equipment is installed on vibration foundations. Pipelines and air ducts are vibroisolated from the structures of the house, since the predominant noise in the apartments located above may not be the base noise from the equipment in the basement, but the one that is transmitted to the building envelope through the vibration of pipelines and equipment foundations. It is forbidden to arrange built-in boiler rooms in residential buildings.

In piping systems connected to the pump, it is necessary to use flexible inserts - rubber-fabric sleeves or rubber-fabric sleeves reinforced with metal spirals, depending on the hydraulic pressure in the network, 700-900 mm long. If there are pipe sections between the pump and the flexible connector, the sections should be fixed to the walls and ceilings of the room on vibration-isolating supports, hangers or through shock-absorbing pads. Flexible connectors should be located as close as possible to the pumping unit, both on the discharge line and on the suction line.

To reduce noise and vibration levels in residential buildings from the operation of heat and water supply systems, it is necessary to isolate the distribution pipelines of all systems from the building structures of the building at the points of their passage through the supporting structures (input to and output from residential buildings). The gap between the pipeline and the foundation at the inlet and outlet must be at least 30 mm.

Prepared based on the materials of the journal Sanitary and epidemiological interlocutor (No. 1 (149), 2015

Page 7 of 21

Due to the fact that at modern power plants the noise, as a rule, exceeds the permissible levels, in recent years, work on noise attenuation has been widely deployed.
There are three main methods for reducing industrial noise: noise reduction at the source itself; reduction of noise on the ways of its propagation; architectural, construction and planning solutions.
The method of reducing noise at the source of its occurrence is to improve the design of the source, to change technological process. The most effective application of this method in the development of new power equipment. Recommendations for reducing noise at the source are given in § 2-2.
For soundproofing various premises power plants (especially engine and boiler rooms) as the most noisy building solutions are used: thickening the outer walls of buildings, the use of double-glazed windows, hollow glass blocks, double doors, multilayer acoustic panels, sealing windows, doors, openings, right choice places of air intake and exhaust of ventilation installations. It is also necessary to ensure good sound insulation between the machine room and the basement, careful sealing of all openings and openings.
When designing a machine room, small rooms with smooth, sound-absorbing walls, ceilings, and floors are avoided. Wall cladding with sound-absorbing materials (SAM) can give a noise reduction of approximately 6-7 dB in medium-sized rooms (3000-5000 m3). For large rooms, the cost-effectiveness of this method becomes controversial.
Some authors, such as G. Koch and H. Schmidt (Germany), as well as R. French (USA), believe that acoustic treatment of walls and ceilings of station premises is not very effective (1-2 dB). The data published by the French Energy Authority (EDF) indicate the promise of this noise suppression method. The treatment of ceilings and walls in boiler rooms at the power plants of Saint-Depy and Chenevier made it possible to obtain a sound reduction of 7-10 dB A.
Stations often construct separate soundproof rooms of control panels, the sound level in which does not exceed 50-60 dB A, which meets the requirements of GOST 12.1.003-76. Service personnel spend 80-90% of their working time in them.
Sometimes acoustic cabins are installed in machine rooms to accommodate service personnel (duty electricians, etc.). These soundproof cabins are an independent frame on supports, to which the floor, ceiling, and walls are attached. Windows and doors of the cabin must have increased sound insulation ( double doors, double glazing). For ventilation, a ventilation unit with silencers at the air inlet and outlet is provided.
If it is necessary to have a quick exit from the cabin, it is performed semi-closed, i.e. one of the walls is missing. In this case, the acoustic efficiency of the cabin is reduced, but there is no need for a ventilation device. According to the data, the limit value of the average sound insulation for semi-enclosed cabins is 12-14 dB.
The use of separate cabins of a closed or semi-closed type in the premises of stations can be attributed to personal means protection of operating personnel from noise. Personal protective equipment also includes Various types earbuds and headphones. The acoustic efficiency of earbuds and, especially, headphones in the high-frequency region is quite high and is at least 20 dB. The disadvantages of these tools is that, along with the noise, the level of useful signals, commands, etc. decreases, and skin irritation is also possible, mainly at elevated ambient temperatures. However, it is recommended that you use earbuds and headphones when operating in environments with noise that exceeds acceptable levels, especially in the high frequency region. Of course, it is advisable to use them for short-term exits from soundproof booths or control panels to areas of increased noise.

One of the ways to reduce noise on the paths of its propagation in the premises of stations are acoustic screens. Acoustic screens are made from thin sheet metal or other dense material, which may have a sound-absorbing lining on one or both sides. Acoustic baffles are usually small and provide local reductions in direct sound from the noise source without significantly affecting the level of reflected sound in the room. In this case, the acoustic efficiency is not very high and depends mainly on the ratio of direct and reflected sound at the calculated point. Increasing the acoustic efficiency of screens can be achieved by increasing their area, which should be at least 25-30% of the sectional area of ​​the room fences in the plane of the screen. At the same time, the efficiency of the screen increases by reducing the energy density of the reflected sound in the screened part of the room. The use of large screens also makes it possible to significantly increase the number of workplaces at which noise reduction is ensured.

The most effective use of screens is in conjunction with the installation of sound-absorbing linings on the enclosing surfaces of the premises. A detailed presentation of the methods for calculating acoustic efficiency and screen design issues is given in and
To reduce noise throughout the engine room, installations that emit intense sound are covered with casings. Sound-insulating casings are usually made of sheet metal lined on the inside of the PDU. It is possible to completely or partially sheathe the surfaces of the installations with soundproofing material.
According to the data given by American experts in noise attenuation at the International Energy Conference in 1969, the complete equipping of high power turbine units (500-1000 MW) with soundproof casings makes it possible to reduce the level of emitted sound by 23-28 dB A. When turbine units are placed in special isolated boxes efficiency increases to 28-34 dB A.
The range of materials used for sound insulation is very wide and, for example, for the insulation of 143 steam units that were introduced into the USA after 1971, it is distributed as follows: aluminum -30%, sheet steel - 27%, gelbest - 18%, asbestos cement - 11%, brick - 10%, porcelain with an external coating - 9%, concrete - 4%.
The following materials are used in prefabricated acoustic panels: soundproofing - steel, aluminum, lead; sound-absorbing foams, mineral wool, fiberglass; damping - bituminous compounds; sealing - rubber, putty, plastics.
Polyurethane foam, fiberglass, sheet lead, vinyl reinforced with lead powder have been widely used.
The Swiss company Air Force, to reduce the noise of the brush apparatus and exciters of high-power turbine units, covers them with a continuous protective casing with a thick layer of sound-absorbing material, in the walls of which silencers are built into the inlet and outlet of the cooling air.

The design of the casing provides free access to these nodes for carrying out current repair. As studies by this company have shown, the soundproofing effect of the casing of the front part of the turbine is most pronounced at high frequencies (6-10 kHz), where it is 13-20 dB, at low frequencies (50-100 Hz) it is insignificant - up to 2-3 dB .

Rice. 2-10. Sound pressure levels at a distance of 1 m from the gas turbine body type GTK-10-Z
1 - with a decorative casing; 2- with housing removed

Particular attention should be paid to sound insulation in power plants with gas turbine drives. Calculations indicate that at gas turbine power plants, the placement of gas turbine engines (GTE) and compressors is most economical in individual boxes (if the number of GTEs is less than five). When placing four gas turbine engines in a common building, the construction cost of the building is 5% higher than when using individual boxes, and with two gas turbine engines, the difference in cost is 28% Therefore, when there are more than five units, it is more economical to place them in a common building. For example, Westinghouse installs five Type 501-AA gas turbines in one acoustically insulated building.

Usually for individual boxes, sheet metal panels are used, on the inside of which there is a sound-absorbing lining. The sound-absorbing cladding can be made of mineral wool or semi-rigid mineral wool slabs in a fiberglass sheath and covered on the side of the noise source with a perforated sheet or metal mesh. The panels are interconnected by bolts, at the joints - elastic gaskets.
Very effective are multilayer panels used abroad, made of inner perforated steel and outer lead sheets, between which a porous sound-absorbing material is placed. Also used are panels with a multilayer inner lining from a layer of vinyl reinforced with lead powder and located between two layers of fiberglass - inner, 50 mm thick, and outer, 25 mm thick.
However, even the simplest decorative and soundproofing skins provide a significant reduction in background noise in machine rooms. On fig. Figures 2-10 show the sound pressure levels in octave frequency bands, measured at a distance of 1 m from the surface of the decorative casing of a gas compressor unit of the GTK-10-3 type. For comparison, there is also a noise spectrum measured with the cover removed at the same points. It can be seen that the effect of a casing made of a steel sheet 1 mm thick, lined inside with glass fiber 10 mm thick, is 10–15 dB in the high-frequency region of the spectrum. The measurements were made in a workshop built according to a standard design, where 6 GTK-10-3 units were installed, covered with decorative cladding.
General and very important issue for energy enterprises of any type is the sound insulation of pipelines. The pipelines of modern installations form a complex extended system with a huge surface of heat and sound radiation.

Rice. 2-11. Sound insulation of the gas pipeline at the Kirchleigeri TPP: a - insulation scheme; b - components of a multilayer panel
1- metal sheathing from sheet steel; 2 - stone wool mats 20 mm thick; 3- aluminum foil; 4 - multilayer panel 20 mm thick (weight I m2 is 10.5 kg); 5 - bituminous felt; 6 layers of thermal insulation; 7- layer foam

This is especially true for combined cycle power plants, which sometimes have a complex branched network of pipelines and a system of gates.

To reduce the noise of pipelines transporting strongly disturbed flows (for example, in areas behind pressure reducing valves), reinforced sound insulation, shown in Fig. 2-11.
Soundproofing effect such a coating is about 30 dB A (reduction of the sound level compared to a "bare" pipeline).
For lining pipelines large diameter multilayer thermal and sound insulation is used, which is strengthened with the help of ribs and hooks welded to the insulated surface.
The insulation consists of a layer of mastic covelite insulation 40-60 mm thick, on top of which a 15-25 mm thick armored wire mesh is laid. The mesh serves to strengthen the covelite layer and create an air gap. The outer layer is formed by mineral wool mats 40-50 mm thick, on top of which a layer of asbestos-cement plaster 15-20 mm thick is applied (80% asbestos grade 6-7 and 20% cement grade 300). This layer is closed (pasted) with some technical fabric. If necessary, the surface is painted. A similar method of sound insulation using previously existing thermal insulation elements can significantly reduce noise. Additional costs associated with the introduction of new sound insulation elements are negligible compared to conventional thermal insulation.
As already noted, the most intense aerodynamic noise occurs during the operation of fans, smoke exhausters, gas turbine and combined-cycle plants, waste devices (blowing lines, safety lines, lines of anti-surge valves of gas turbine compressors). ROU can also be included here.

Silencers are used to limit the spread of such noise along the flow of the transported medium and its release into the surrounding atmosphere. Silencers occupy an important place in the overall system of measures to reduce noise at power plants, because sound from working cavities can be directly transmitted through intake or discharge devices into the surrounding atmosphere, creating the highest levels of sound pressure (compared to other sources of sound radiation). It is also useful to limit the propagation of noise through the transported medium in order to prevent its excessive penetration through the walls of the pipeline to the outside by installing noise suppressors (for example, a pipeline section behind a pressure reducing valve).
On modern powerful steam turbine units, silencers are placed on the intake of the blower fans. In this case, the pressure drop is strictly limited by the upper limit of the order of 50-f-100 Pa. The required efficiency of these silencers is usually from 15 to 25 dB in the 200-1000 Hz section of the spectrum in terms of installation effect.
Thus, at the Robinson TPP (USA) with a capacity of 900 MW (two blocks of 450 MW each), to reduce the noise of blower fans, with a capacity of 832,000 m3/h, suction silencers were installed. The muffler consists of a housing (steel sheets 4.76 mm thick), in which a grid of sound-absorbing plates is located. The body of each plate is made of perforated galvanized steel sheets. Sound-absorbing material - mineral wool, protected by fiberglass.
Koppers manufactures standard sound attenuating blocks used in fan silencers used for drying pulverized coal, air supply to boiler burners, room ventilation.
The noise of smoke exhausters often poses a significant danger, since it can escape into the atmosphere through the chimney and spread over considerable distances.
For example, at the TPP "Kirchlengern" (Germany), the sound level near the chimney was 107 dB at a frequency of 500-1000 Hz. In this regard, it was decided to install an active silencer in the chimney of the boiler building (Fig. 2-12). The muffler consists of twenty wings 1 with a diameter of 0.32 m and a length of 7.5 m. load-bearing structure. The rocker consists of a body made of sheet steel and an absorber (mineral wool) protected by fiberglass. After installing the silencer, the sound level at the chimney was 89 dB A.
The complex task of reducing the noise of gas turbines requires an integrated approach. Below is an example of a set of measures to combat the noise of gas turbines, an essential part of which are silencers in gas-air paths.
To reduce the noise level of a gas turbine unit with a 17.5 MW Olympus 201 turbojet engine, an analysis of the required degree of noise attenuation of the installation was carried out. It was required that the octave noise spectrum, measured at a distance of 90 m from the base of the steel chimney, would not exceed PS-50. The layout shown in fig. 2-13 provides attenuation of GTU suction noise by various elements (dB):

A two-stage plate-type muffler with high and low frequency stages is installed at the air inlet to the gas turbine. The silencer stages are installed after the cycle air cleaning filter.
An annular low-frequency muffler is installed on the GTU exhaust. The results of the analysis of the noise field of the GTU with the turbojet engine on the exhaust before and after the installation of the muffler (dB):

To reduce noise and vibrations, the GTU gas generator was enclosed in a casing, and silencers were installed at the air inlet in the ventilation system. As a result, the noise measured at a distance of 90 m was:

Similar noise suppression systems are used for their gas turbines by the American firms Solar, General Electric, and the Japanese firm Hitachi.
For high-capacity gas turbines, silencers at the air intake are often very bulky and complex engineering structures. An example is the noise suppression system at the Var gas turbine CHPP (Germany), which has two Brown-Boveri GTUs with a capacity of 25 MW each.

Rice. 2-12. Installation of a silencer in the chimney of Kirchlengerä TPP

Rice. 2-13. Noise suppression system for an industrial gas turbine with an aircraft gas turbine engine as a gas generator
1- outer sound-absorbing ring; 2- internal sound-absorbing ring; 3- bypass cover; 4 - air filter; 5- turbine exhaust; 6 - plates of a high-frequency silencer on suction; 7- plates of the low-frequency silencer on suction

The station is located in the central part of the populated area. A silencer is installed at the intake of the GTU, consisting of three stages arranged in series. The sound-absorbing material of the first stage, designed to dampen low-frequency noise, is mineral wool coated with synthetic fabric and protected by perforated metal sheets. The second stage is similar to the first, but differs in smaller gaps between the plates. Third step
consists of metal sheets covered with sound-absorbing material and serves to absorb high-frequency noise. After installing the silencer, the noise of the power plant, even at night, did not exceed the norm adopted for this area (45 dB L).
Similar complex two-stage mufflers are installed at a number of powerful domestic installations, for example, at the Krasnodar CHPP (GT-100-750), Nevinnomysskaya State District Power Plant (PGU-200). A description of their construction is given in § 6-2.
The cost of noise suppression measures at these stations amounted to 1.0-2.0% of the total cost of the station, or about 6% of the cost of the gas turbine itself. In addition, the use of silencers is associated with a certain loss of power and efficiency. The construction of silencers requires the use of large quantities expensive materials and quite laborious. Therefore, the issues of optimizing the design of silencers are of particular importance, which is impossible without knowledge of the most advanced calculation methods and the theoretical basis of these methods.

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