Recommendations for reducing the noise level in the boiler room. Calculation and design of noise silencers for power plants are common methods for reducing noise in power plants. How to reduce the noise of the boiler room when designing

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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 by the beginning of the 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.

NOISE LEVEL

Sound power is measured in decibels (dB) in the frequency range from 31.5 to 16000 Hz and in the middle of each frequency band, i.e. at frequencies 31.5; 63; 125; 250 Hz etc. A person perceives sound in the range from 63 to 800 Hz.

Sound power in dB is divided into levels A, B, C and D. The permissible norm of the general noise level is considered to be level A, which is closest to the human sensitivity range. To designate this characteristic, we most use the term "Sound pressure level".

NOISE SOURCE

A running engine is a source of mechanical noise originating in
gas distribution mechanism, fuel pump, etc., as well as appearing in the combustion chambers, as a result of vibration, air intake and fan operation, if installed. Generally, intake air and radiator noise is less than mechanical noise. Noise level data can be found in the Product Information Manual if required. Noise can be reduced by using a sound-absorbing coating. If the mechanical noise is attenuated to the level 5 mentioned in the Noise level section, attention should be paid to the air and fan noise.

An effective and relatively cheap way is to cover the engine with a casing. At a distance of 1 m from the housing, sound attenuation reaches 10 dB(A). Only specially designed housings are effective, so it is advisable to consult with experts regarding its parameters.

If there are certain requirements for noise outside the premises in which the units are located, the following conditions must be observed:

1) Building structure

The outer walls are made of double bricks with

voids.

Windows - double glazing with spacing

between panes 200 mm.

Doors - double doors with tambour or

single, with screen wall opposite

doorway.

2) Ventilation

Openings for fresh air intake and heated air exhaust must be equipped with noise barriers. These issues should be discussed by the Owner with the Manufacturer.

Screens should not reduce the cross section of the ducts, as this will increase the resistance on the fan. For larger engines requiring more air, screens need to be correspondingly larger and the building needs to be able to fit them properly.

3) Vibration isolation mounts

Mounting the units on anti-vibration mounts prevents the transmission of vibration to walls, other parts of the unit, etc. Vibration is often one of the causes of noise. (See anti-vibration mounts).

4) Exhaust damping

It allows attenuating noise by 30...35 dB(A) at a distance of 1 m from the outer wall of the room, provided that high-quality sound absorbers and exhaust silencers are used at the inlet and outlet.

To eliminate each of these noises, different methods are required. In addition, each type of noise has its own properties and parameters, and they must be taken into account when manufacturing low-noise refrigeration chillers.

You can apply a large amount of different insulation and not achieve the desired result, but on the contrary, by applying the minimum amount of the “right” material in the right place, using insulation according to the technology, you can achieve excellent low noise.

To understand the essence of the soundproofing process, let's turn to the main methods for achieving low-noise industrial water coolers.

First you need to define the basic terms.

Noise — undesirable, unfavorable for the target human activity within the radius of its propagation sound.

Sound — wave propagation of particles oscillating due to external influence in some medium - solid, liquid or gaseous.

There are other less common and significantly more expensive and cumbersome solutions to achieve near-absolute silence, if required by the chiller installation site. For example, sound insulation of the technical room where the compressor-evaporative unit of the chiller is located, the use of water condensers or wet cooling towers without the use of fans, and some other more exotic ones, but they are extremely rarely used in practice.

V.B. Tupov
Moscow Power Engineering Institute (Technical University)

ANNOTATION

The original MPEI developments on noise reduction from the power equipment of thermal power plants and boiler houses are considered. Examples of noise reduction from the most intense noise sources are given, namely from steam emissions, combined-cycle plants, draft machines, hot water boilers, transformers and cooling towers, taking into account the requirements and specifics of their operation at energy facilities. The test results of silencers are given. The given data allow us to recommend MPEI mufflers for wide use at the country's energy facilities.

1. INTRODUCTION

Solutions of environmental issues in the operation of power equipment are a priority. Noise is one of the important factors polluting the environment, the reduction of the negative impact of which on the environment is obligated by the laws "On the Protection of Atmospheric Air" and "On the Protection of the Environment", and sanitary standards SN 2.2.4 / 2.1.8.562-96 establish permissible noise levels at workplaces and residential areas.

The operation of power equipment in the normal mode is associated with noise emission, which exceeds sanitary standards not only on the territory of power facilities, but also on the territory of the surrounding area. This is especially important for energy facilities located in large cities near residential areas. The use of combined cycle plants (CCGT) and gas turbine plants (GTP), as well as equipment of higher technical parameters, is associated with an increase in sound pressure levels in the surrounding area.

Some power equipment has tonal components in its emission spectrum. The round-the-clock cycle of operation of power equipment causes a special danger of noise exposure for the population at night.

In accordance with sanitary standards, sanitary protection zones (SPZ) of TPPs with an equivalent electric power of 600 MW and above, using coal and fuel oil as fuel, must have a SPZ of at least 1000 m, operating on gas and oil gas fuel - at least 500 m. CHPPs and district boiler houses with a thermal capacity of 200 Gcal and above, operating on coal and fuel oil, the SPZ is at least 500 m, and for those operating on gas and reserve oil fuel - at least 300 m.

Sanitary norms and rules establish the minimum dimensions of the sanitary zone, and the actual dimensions may be larger. Excess of permissible norms from constantly operating equipment of thermal power plants (TPP) can reach for working areas - 25-32 dB; for territories of residential areas - 20-25 dB at a distance of 500 m from a powerful thermal power plant (TPP) and 15-20 dB at a distance of 100 m from a large district thermal plant (RTS) or quarterly thermal power plant (KTS). Therefore, the problem of reducing the noise impact from energy facilities is relevant, and in the near future its importance will increase.

2. EXPERIENCE IN REDUCING NOISE FROM POWER EQUIPMENT

2.1. Main areas of work

The excess of sanitary standards in the surrounding area is formed, as a rule, by a group of sources, the development of noise reduction measures, which are given great attention both abroad and in our country. Works on noise suppression of power equipment of such companies as Industrial acoustic company (IAC), BB-Acustic, Gerb and others are known abroad, and in our country, the developments of YuzhVTI, NPO CKTI, ORGRES, VZPI (Open University), NIISF, VNIAM, etc. . .

Since 1982, the Moscow Power Engineering Institute (Technical University) has also been carrying out a set of works to solve this problem. Here, in recent years, new effective silencers have been developed and implemented at large and small power facilities for the most intense noise sources from:

steam emissions;

combined-cycle plants;

draft machines (smoke exhausters and draft fans);

hot water boilers;

transformers;

cooling towers and other sources.

Below are examples of noise reduction from power equipment developed by MPEI. The work on their implementation has a high social significance, which consists in reducing the noise impact to sanitary standards for a large number of the population and personnel of energy facilities.

2.2. Examples of noise reduction from power equipment

Discharges of steam from power boilers into the atmosphere is the most intense, albeit short-term, source of noise both for the territory of the enterprise and for the surrounding area.

Acoustic measurements show that at a distance of 1 - 15 m from the steam emission of a power boiler, sound levels exceed not only the permissible, but also the maximum permissible sound level (110 dBA) by 6 - 28 dBA.

Therefore, the development of new efficient steam silencers is an urgent task. A steam emission silencer (MPEI silencer) was developed.

The steam silencer is available in various modifications depending on the required emission noise reduction and steam characteristics.

Currently, MPEI steam silencers have been introduced at a number of power facilities: Saransk Thermal Power Plant No. 2 (CHP-2) of JSC Territorial Generating Company-6, OKG-180 boiler of JSC Novolipetsk Metallurgical Plant, CHPP-9, CHPP-11 of JSC " Mosenergo. Steam flow rates through silencers ranged from 154 t/h at Saransk CHPP-2 to 16 t/h at CHPP-7 of OAO Mosenergo.

MEI mufflers were installed on the exhaust pipelines after the CHP of boilers st. No. 1, 2 of CHPP-7 of the CHPP-12 branch of OAO Mosenergo. The efficiency of this noise suppressor, obtained from the measurement results, was 1.3 - 32.8 dB in the entire spectrum of normalized octave bands with geometric mean frequencies from 31.5 to 8000 Hz.

On the boilers No. 4, 5 CHPP-9 JSC "Mosenergo" several MEI mufflers were introduced at the steam discharge after the main safety valves (MPV). The tests carried out here showed that the acoustic efficiency was 16.6 - 40.6 dB in the entire spectrum of normalized octave bands with geometric mean frequencies of 31.5 - 8000 Hz, and in terms of sound level - 38.3 dBA.

MPEI mufflers, in comparison with foreign and other domestic analogues, have high specific characteristics, which allow achieving the maximum acoustic effect with a minimum muffler weight and maximum steam flow through the muffler.

MPEI steam silencers can be used to reduce the noise of discharges of superheated and wet steam, natural gas, etc. into the atmosphere. The experience of using MPEI steam silencers showed the necessary acoustic efficiency and reliability of silencers at various facilities.

When developing noise suppression measures for gas turbines, the main attention was paid to the development of silencers for gas paths.

According to the recommendations of the MPEI, the designs of silencers for the gas paths of waste heat boilers of the following brands were made: KUV-69.8-150 manufactured by JSC Dorogobuzhkotlomash for GTPP Severny Settlement, P-132 manufactured by JSC Podolsky Machine-Building Plant (JSC PMZ) for Kirishskaya GRES, P-111 manufactured by JSC "PMZ" for CHPP-9 of JSC "Mosenergo", a waste heat boiler under the license of the company "Nooter / Eriksen" for the power unit CCGT-220 of Ufimskaya CHPP-5, KGT-45 / 4.0- 430-13 / 0.53-240 for the Novy Urengoy Gas Chemical Complex (GCC).

For the GTU-CHP "Severny Settlement" a set of works was carried out to reduce the noise of gas paths.

The Severny Settlement GTU-CHPP contains a double-hull CHP unit designed by OAO Dorogobuzhkotlomash, which is installed after two FT-8.3 gas turbines from Pratt & Whitney Power Systems. The evacuation of flue gases from the boiler is carried out through one chimney.

Conducted acoustic calculations showed that in order to comply with sanitary standards in a residential area at a distance of 300 m from the chimney mouth, it is necessary to reduce noise in the range from 7.8 dB to 27.3 dB at geometric mean frequencies of 63-8000 Hz.

The dissipative lamellar noise silencer developed by MPEI to reduce the exhaust noise of gas turbine units with CU is located in two metal ducts of noise attenuation of the CU with dimensions of 6000x6054x5638 mm above the convective packs in front of the confusers.

Kirishskaya GRES is currently implementing a CCGT-800 combined-cycle unit with a P-132 horizontal unit and a SGT5-400F gas turbine (Siemens).

The calculations performed showed that the required reduction in the noise level from the gas turbine exhaust tract is 12.6 dBA to ensure a sound level of 95 dBA at 1 m from the mouth of the chimney.

To reduce noise in the gas paths of the KU P-132 of the Kirishskaya GRES, a cylindrical muffler was developed, which is located in the chimney with an internal diameter of 8000 mm.

The muffler consists of four cylindrical elements placed evenly in the chimney, while the relative flow area of ​​the muffler is 60%.

The calculated efficiency of the silencer is 4.0-25.5 dB in the range of octave bands with geometric mean frequencies of 31.5 - 4000 Hz, which corresponds to an acoustic efficiency in terms of sound level of 20 dBA.

The use of silencers to reduce noise from smoke exhausters using the example of Mosenergo's CHPP-26 in horizontal sections is given in.

In 2009, to reduce the noise of the gas path behind the centrifugal smoke exhausters D-21.5x2 of the TGM-84 boiler st. No. 4 of CHPP-9, a plate noise silencer was installed on a straight vertical section of the boiler flue behind the smoke exhausters in front of the entrance to the chimney at the level of 23.63 m.

The lamellar silencer for the flue of the TGM CHP-9 boiler is a two-stage design.

Each stage of the muffler consists of five plates 200 mm thick and 2500 mm long, placed evenly in the flue with dimensions 3750x2150 mm. The distance between the plates is 550 mm, the distance between the outer plates and the flue wall is 275 mm. With this arrangement of plates, the relative flow area is 73.3%. The length of one silencer stage without fairings is 2500 mm, the distance between the stages of the silencer is 2000 mm, inside the plates there is a non-flammable, non-hygroscopic sound-absorbing material, which is protected from blowing by glass cloth and perforated metal sheet. The muffler has an aerodynamic resistance of about 130 Pa. The weight of the silencer structure is about 2.7 tons. According to the test results, the acoustic efficiency of the silencer is 22-24 dB at geometric mean frequencies of 1000-8000 Hz.

An example of a comprehensive study of noise suppression measures is the MPEI's development to reduce noise from smoke exhausters at Mosenergo's HPP-1. Here, high demands were placed on the aerodynamic resistance of silencers, which had to be placed in the existing gas ducts of the station.

To reduce the noise of gas paths of boilers st. No. 6, 7 HPP-1 of the branch of JSC "Mosenergo" MPEI has developed a whole system of noise suppression. The noise suppression system consists of the following elements: a plate silencer, gas path turns lined with sound-absorbing material, a dividing sound-absorbing partition and a ramp. The presence of a separating sound-absorbing partition, a ramp and sound-absorbing lining of the turns of the boiler gas ducts, in addition to reducing noise levels, helps to reduce the aerodynamic resistance of the gas paths of power boilers st. No. 6, 7 as a result of eliminating the collision of flue gas flows at their junction, organizing smoother turns of flue gases in gas paths. Aerodynamic measurements showed that the total aerodynamic resistance of the gas paths of the boilers downstream of the smoke exhausters did not practically increase due to the installation of a noise suppression system. The total weight of the noise suppression system was about 2.23 tons.

The experience of reducing the noise level from the air intakes of the draft fans of boilers is given in. The article considers examples of reducing the noise of air intakes of boilers with mufflers designed by MPEI. Here are the mufflers for the air intake of the VDN-25x2K blower fan of the BKZ-420-140 NGM st. No. 10 CHPP-12 JSC "Mosenergo" and hot water boilers through underground mines (on the example of boilers

PTVM-120 RTS "South Butovo") and through the channels located in the wall of the boiler building (for example, boilers PTVM-30 RTS "Solntsevo"). The first two cases of air duct layout are quite typical for power and hot water boilers, and the feature of the third case is the absence of areas where a silencer can be installed and high air flow rates in the channels.

Measures were developed and implemented in 2009 to reduce noise with the help of sound-absorbing screens from four communication transformers of the brand TTs TN-63000/110 at CHPP-16 of OAO Mosenergo. Sound-absorbing screens are installed at a distance of 3 m from the transformers. The height of each sound-absorbing screen is 4.5 m, and the length varies from 8 to 11 m. The sound-absorbing screen consists of separate panels installed in special racks. Steel panels with sound-absorbing cladding are used as screen panels. The panel on the front side is closed with a corrugated metal sheet, and on the side of the transformers - with a perforated metal sheet with a perforation ratio of 25%. Inside the screen panels is a non-flammable, non-hygroscopic sound-absorbing material.

The test results showed that the sound pressure levels after installing the screen decreased at the control points to 10-12 dB.

At present, projects have been developed to reduce noise from cooling towers and transformers at CHPP-23 and from cooling towers at CHPP-16 of OAO Mosenergo using screens.

Active implementation of MPEI noise suppressors for hot water boilers continued. Over the past three years alone, silencers have been installed on boilers PTVM-50, PTVM-60, PTVM-100 and PTVM-120 at RTS Rublevo, Strogino, Kozhukhovo, Volkhonka-ZIL, Biryulyovo, Khimki -Khovrino, Krasny Stroitel, Chertanovo, Tushino-1, Tushino-2, Tushino-5, Novomoskovsk, Babushkinskaya-1, Babushkinskaya-2, Krasnaya Presnya ”, KTS-11, KTS-18, KTS-24 of Moscow, etc.

Tests of all installed silencers have shown high acoustic efficiency and reliability, which is confirmed by implementation certificates. More than 200 silencers are currently in operation.

The introduction of MPEI mufflers continues.

In 2009, an agreement was signed between MPEI and the Central Repair Plant (TsRMZ, Moscow) in the field of supply of integrated solutions to reduce noise impact from power equipment. This will make it possible to more widely implement MPEI developments at the country's energy facilities. CONCLUSION

The MPEI muffler complex designed to reduce noise from various power equipment has shown the necessary acoustic efficiency and takes into account the specifics of work at power facilities. Silencers have passed long-term operational approbation.

The reviewed experience of their application makes it possible to recommend MPEI mufflers for wide use at the country's energy facilities.

BIBLIOGRAPHY

1. Sanitary protection zones and sanitary classification of enterprises, structures and other objects. SanPiN 2.2.1/2.1.1.567-01. M.: Ministry of Health of Russia, 2001.

2. Grigoryan F.E., Pertsovsky E.A. Calculation and design of noise suppressors for power plants. L.: Energy, 1980. - 120 p.

3. Fight against noise in production / ed. E.Ya. Yudin. M.: Mashinostroenie. 1985. - 400 p.

4. Tupov V.B. Noise reduction from power equipment. Moscow: MPEI Publishing House. 2005. - 232 p.

5. Tupov V.B. Noise impact of energy facilities on the environment and methods of its reduction. In the reference book: "Industrial heat power engineering and heat engineering" / ed. A.V. Klimenko, V.M. Zorina, MPEI Publishing House, 2004. V. 4. S. 594-598.

6. Tupov V.B. Noise from power equipment and ways to reduce it. In the textbook: "Ecology of Energy". M.: MEI Publishing House, 2003. S. 365-369.

7. Tupov V.B. Noise reduction from power equipment. Modern environmental technologies in the electric power industry: Information collection / ed. V.Ya. Putilov. Moscow: MEI Publishing House, 2007, pp. 251-265.

8. Marchenko M.E., Permyakov A.B. Modern noise suppression systems for discharges of large steam flows into the atmosphere. Teploenergetika. 2007. No. 6. pp. 34-37.

9. Lukashchuk V.N. Noise during blowdowns of superheaters and the development of measures to reduce its impact on the environment: diss ... cand. those. Sciences: 05.14.14. M., 1988. 145 p.

10. Yablonik L.R. Noise-protective structures of turbine and boiler equipment: theory and calculation: diss. ... doc. those. Sciences. SPb., 2004. 398 p.

11. Muffler for steam emissions (options): Patent

for utility model 51673 RF. Application No. 2005132019. Appl. October 18, 2005 / V.B. Tupov, D.V. Chugunkov. - 4 s: ill.

12. Tupov V.B., Chugunkov D.V. Silencer of steam emission noise // Electric stations. 2006. No. 8. pp. 41-45.

13. Tupov V.B., Chugunkov D.V. The use of noise suppressors for steam discharges into the atmosphere / Ulovoe in the Russian electric power industry. 2007. No. 12. pp.41-49

14. Tupov V.B., Chugunkov D.V. Silencers of noise on discharges of steam of power boilers// Thermal power engineering. 2009. No. 8. pp.34-37.

15. Tupov V.B., Chugunkov D.V., Semin S.A. Reduction of noise from exhaust tracts of gas turbine plants with waste heat boilers // Teploenergetika. 2009. No. 1. S. 24-27.

16. Tupov V.B., Krasnov V.I. Experience in reducing the noise level from the air intakes of the draft fans of boilers// Thermal Power Engineering. 2005. No. 5. pp. 24-27

17. Tupov V.B. Noise problem from power stations in Moscow// 9th International Congress on Sound and Vibration Orlando, Florida, USA, 8-11, July 2002.P. 488-496.

18. Tupov V.B. Noise reduction from blow fans of hot-water boilers//ll th International Congress on Sound and Vibration, St.Petersburg, 5-8 July 2004. P. 2405-2410.

19. Tupov V.B. Ways to reduce noise from hot water boilers RTS // Thermal power engineering. No. 1. 1993. S. 45-48.

20. Tupov V.B. Noise problem from power stations in Moscow// 9th International Congress on Sound and Vibration, Orlando, Florida, USA, 8-11, July 2002. P. 488^96.

21. Lomakin B.V., Tupov V.B. Experience in reducing noise in the area adjacent to CHPP-26 // Electric Stations. 2004. No. 3. pp. 30-32.

22. Tupov V.B., Krasnov V.I. Problems of noise reduction from energy facilities during expansion and modernization / / I specialized thematic exhibition "Ecology in the energy sector-2004": Sat. report Moscow, All-Russian Exhibition Center, October 26-29, 2004. M., 2004. S. 152-154.

23. Tupov V.B. Experience in reducing the noise of power plants / Ya1 All-Russian scientific and practical conference with international participation "Protection of the population from increased noise exposure", March 17-19, 2009 St. Petersburg., P. 190-199.

Ph.D. L.V. Rodionov, Head of Research Support Department; Ph.D. S.A. Gafurov, senior researcher; Ph.D. V.S. Melentiev, Senior Researcher; Ph.D. A.S. Gvozdev, Samara National Research University named after Academician S.P. Koroleva, Samara

To provide hot water and heating for modern multi-apartment buildings (MKD), rooftop boilers are sometimes included in projects. This solution is in some cases cost-effective. At the same time, often, when installing boilers on foundations, proper vibration isolation is not provided. As a result, residents of the upper floors are subject to constant noise exposure.

According to the sanitary standards in force in Russia, the sound pressure level in residential premises should not exceed 40 dBA - during the day and 30 dBA - at night (dBA - acoustic decibel, a unit of noise level, taking into account human perception of sound. - Approx. ed.).

Specialists of the Institute of Machine Acoustics at the Samara State Aerospace University (IAM at SSAU) measured the sound pressure level in the living room of an apartment located under the roof boiler house of a residential building. It turned out that the equipment of the rooftop boiler house was the source of the noise. Despite the fact that this apartment is separated from the roof boiler house by a technical floor, the results of measurements showed an excess of daily sanitary standards, both in terms of the equivalent level and at an octave frequency of 63 Hz (Fig. 1).

The measurements were taken in the daytime. At night, the operating mode of the boiler room practically does not change, and the background noise level may be lower. Since it turned out that the “problem” is already present during the day, it was decided not to carry out measurements at night.

Picture 1 . The level of sound pressure in the apartment in comparison with sanitary standards.

Noise and vibration source localization

To more accurately determine the “problem” frequency, sound pressure levels were measured in the apartment, the boiler room and on the technical floor in different operating modes of the equipment.

The most characteristic operating mode of the equipment, in which a tonal frequency appears in the low-frequency region, is the simultaneous operation of three boilers (Fig. 2). It is known that the frequency of working processes of boilers (burning inside) is quite low and falls in the range of 30-70 Hz.

Figure 2. Sound pressure level in different rooms when three boilers are operating simultaneously

From fig. 2 shows that the frequency of 50 Hz dominates in all measured spectra. Thus, boilers make the main contribution to the spectra of sound pressure levels in the premises under study.

The level of background noise in the apartment does not change much when the boiler equipment is turned on (except for a frequency of 50 Hz), so we can conclude that the sound insulation of the two floors that separate the boiler room from the living rooms is sufficient to reduce the level of airborne noise produced by boiler equipment to sanitary standards. Therefore, one should look for other (not direct) ways of noise (vibration) propagation. It is likely that the high sound pressure level at 50 Hz is due to structure-borne noise.

In order to localize the source of structural noise in residential premises, as well as to identify vibration propagation paths, additional measurements of vibration acceleration were carried out in the boiler room, on the technical floor, as well as in the living room of the apartment on the top floor.

The measurements were carried out at various operating modes of the boiler equipment. On fig. Figure 3 shows the vibration acceleration spectra for the mode in which all three boilers operate.

Based on the results of the measurements, the following conclusions were made:

- in the apartment on the top floor under the boiler room, sanitary standards are not met;

- the main source of increased noise in residential premises is the working process of combustion in boilers. The prevailing harmonic in the noise and vibration spectra is the frequency of 50 Hz.

- the lack of proper vibration isolation of the boiler from the foundation leads to the transmission of structural noise to the floor and walls of the boiler room. Vibration spreads both through the boiler supports and through pipes with transmission from them to the walls, as well as the floor, i.e. in places of rigid connection.

- Measures should be developed to combat noise and vibration in the path of their propagation from the boiler.

a) b)
in)

Figure 3 . Vibration acceleration spectra: a - on the support and foundation of the boiler, on the floor of the boiler room; b - on the support of the boiler exhaust pipe and on the floor near the boiler exhaust pipe; c - on the wall of the boiler room, on the wall of the technical floor and in the living room of the apartment.

Development of a vibration protection system

Based on a preliminary analysis of the mass distribution of the structure of the gas boiler and equipment, cable vibration isolators VMT-120 and VMT-60 with a nominal load per vibration isolator (VI) of 120 and 60 kg, respectively, were selected for the project. The scheme of the vibration isolator is shown in fig. four.

Figure 4 3D model of a cable vibration isolator of the TDC model range.

Figure 5 Schemes for fixing vibration isolators: a) support; b) hanging; c) lateral.

Three variants of the scheme for fixing vibration isolators have been developed: support, suspension and side (Fig. 5).

Calculations have shown that the side scheme of the installation can be implemented using 33 VMT-120 vibration isolators (for each boiler), which is not economically feasible. In addition, very serious welding work is expected.

When implementing a suspended scheme, the entire structure becomes more complicated, since it is necessary to weld wide and rather long corners to the boiler frame, which will also be welded from several profiles (to provide the necessary mounting surface).

In addition, the technology of installing the boiler frame on these skids with VI is complicated (it is inconvenient to fix the VI, it is inconvenient to place and center the boiler, etc.). Another disadvantage of such a scheme is the free movement of the boiler in lateral directions (swinging in the transverse plane on the VI). The number of vibration isolators VMT-120 for this scheme is 14.

The frequency of the vibration protection system (VZS) is about 8.2 Hz.

The third, most promising and technologically simpler option is with a standard reference circuit. It will require 18 VMT-120 vibration isolators.

The calculated frequency of the VZS is 4.3 Hz. In addition, the design of the VIs themselves (part of the cable rings is located at an angle) and their competent placement along the perimeter (Fig. 6) makes it possible to perceive with such a scheme a lateral load, the value of which will be about 60 kgf for each VI, while the vertical load on each VI is about 160 kgf.

Figure 6 Placement of vibration isolators on the frame with a reference scheme.

Vibration protection system design

Based on the data of the conducted static tests and the dynamic calculation of the VI parameters, a vibration protection system for the boiler house of a residential building was developed (Fig. 7).

The object of vibration protection includes three boilers of the same design 1 installed on concrete foundations with metal ties; piping system 2 for the supply of cold and the removal of heated water, as well as the removal of combustion products; pipe system 3 for supplying gas to the burners of the boilers.

The created vibration protection system includes external vibration protection supports for boilers 4 designed to support pipelines 2 ; internal vibration protection belt of boilers 5 designed to isolate the vibration of boilers from the floor; external anti-vibration supports 6 for gas pipes 3.

Figure 7 General view of the boiler house with the vibration protection system installed.

The main design parameters of the vibration protection system:

1. The height from the floor to which it is necessary to raise the load-bearing frames of the boilers is 2 cm (installation tolerance minus 5 mm).

2. The number of vibration isolators per one boiler: 19 VMT-120 (18 in the inner belt bearing the weight of the boiler, and 1 on the external support for damping vibrations of the water pipeline), as well as 2 VMT-60 vibration isolators on external supports - for vibration protection of the gas pipeline.

3. The “support” type loading scheme works in compression, providing good vibration isolation. The natural frequency of the system is in the range of 5.1-7.9 Hz, which provides effective vibration protection in the region above 10 Hz.

4. The damping coefficient of the vibration protection system is 0.4-0.5, which provides an amplification at resonance of no more than 2.6 (oscillation amplitude no more than 1 mm with an input signal amplitude of 0.4 mm).

5. To adjust the horizontal position of the boilers on the sides of the boiler in the U-shaped profiles, there are nine seats for vibration isolators of the same type. Only five are nominally installed.

During installation, it is possible to place the vibration isolators in any order in any of the nine places provided to achieve the alignment of the center of mass of the boiler and the center of rigidity of the vibration protection system.

6. Advantages of the developed anti-vibration system: simplicity of design and installation, insignificant amount of boilers lifting above the floor, good damping characteristics of the system, possibility of adjustment.

The effect of using the developed vibration protection system

With the introduction of the developed vibration protection system, the sound pressure level in the living quarters of the apartments on the upper floors decreased to an acceptable level (Fig. 8) . The measurements were also made at night.

From the graph in Fig. 8 it can be seen that in the normalized frequency range and in terms of the equivalent sound level, sanitary standards in the living room are met.

The efficiency of the developed vibration protection system when measured in a residential area at a frequency of 50 Hz is 26.5 dB, and 15 dBA in terms of the equivalent sound level (Fig. 9).

Figure 8 . The level of sound pressure in the apartment in comparison with sanitary standards, taking into account developed vibration protection system.

Figure 9 Sound pressure level in one-third octave frequency bands in a residential area when three boilers are operating simultaneously.

Conclusion

The created vibration protection system makes it possible to protect a residential building equipped with a rooftop boiler from vibrations generated by the operation of gas boilers, as well as to ensure normal vibration mode of operation for the gas equipment itself, together with the piping system, increasing the service life and reducing the likelihood of accidents.

The main advantages of the developed vibration protection system are simplicity of design and installation, low cost compared to other types of vibration isolators, resistance to temperatures and pollution, a small amount of boiler elevation above the floor, good damping characteristics of the system, and the ability to adjust.

The vibration protection system prevents the spread of structural noise from the equipment of the roof boiler through the building structure, thereby reducing the sound pressure level in residential premises to an acceptable level.

Literature

1. Igolkin, A.A. Reducing noise in a residential area through the use of vibration isolators [Text] / A.A. Igolkin, L.V. Rodionov, E.V. Chess // Security in the technosphere. No. 4. 2008. S. 40-43.

2. SN 2.2.4 / 2.1.8.562-96 "Noise at workplaces, in the premises of residential, public buildings and on the territory of residential development", 1996, 8 p.

3. GOST 23337-78 “Noise. Methods for measuring noise in a residential area and in residential and public buildings”, 1978, 18 p.

4. Shakhmatov, E.V. A comprehensive solution to the problems of vibroacoustics of mechanical engineering and aerospace products [Text] / E.V. Chess // LAP LAMBERT Academic Publishing GmbH&CO.KG. 2012. 81 p.

From the editor. On October 27, 2017, Rospotrebnadzor published information on its official website "On the impact of physical factors, including noise, on public health", in which he notes that in the structure of citizens' complaints about various physical factors, the largest share (over 60%) is made up of complaints about noise. The main of them are residents' complaints, including acoustic discomfort from ventilation systems and refrigeration equipment, noise and vibration during the operation of heating equipment.

The reasons for the increased noise level generated by these sources are the insufficiency of noise protection measures at the design stage, the installation of equipment with deviation from design solutions without assessing the generated noise and vibration levels, the unsatisfactory implementation of noise protection measures at the commissioning stage, the placement of equipment not provided for by the project, and also unsatisfactory control over the operation of equipment.

The Federal Service for Supervision of Consumer Rights Protection and Human Welfare draws the attention of citizens to the fact that under the adverse effects of physical factors, incl. noise, you should contact the territorial Office of Rospotrebnadzor for the subject of the Russian Federation.