Calculation and design of noise mufflers for power plants - general methods of noise reduction in power plants. How to reduce the noise level of the boiler room: at the design stage and by special means Recommendations for reducing the noise level in the boiler room

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All supplied boiler equipment is certified and has permits 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.

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

ANNOTATION

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

1. INTRODUCTION

Solutions to environmental issues during the operation of power equipment are a priority. Noise is one of the important polluting factors, reducing negative impact which the environment is obliged by the laws "On the protection of atmospheric air" and "On the protection of the environment natural environment", And the sanitary standards SN 2.2.4 / 2.1.8.562-96 establish acceptable levels noise in workplaces and residential areas.

The normal operation of power equipment 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 (GTU), as well as equipment of higher technical parameters, is associated with an increase in sound pressure levels in the surrounding area.

Some energy equipment has tonal components in its emission spectrum. The round-the-clock cycle of power equipment operation creates 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 an SPZ of at least 1000 m, operating on gas and gas-oil fuel - at least 500 m. For CHP and regional 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 fuel oil - at least 300 m.

Sanitary codes and regulations establish the minimum dimensions of the sanitary zone, and the actual dimensions may be larger. Exceeding the permissible norms from constantly operating equipment of thermal power plants (TPP) can reach for working zones - 25-32 dB; for the 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 heating station (RTS) or quarterly thermal power plant (KTS). Therefore, the problem of reducing the noise impact from energy facilities is urgent, and in the near future its importance will increase.

2. EXPERIENCE IN REDUCING NOISE FROM POWER EQUIPMENT

2.1. Main directions of work

The excess of sanitary standards in the surrounding area is formed, as a rule, by a group of sources, the development of measures to reduce noise, which are given great attention both abroad and in our country. Abroad, there are works on noise suppression of power equipment of such companies as Industrial acoustic company (IAC), BB-Acustic, Gerb and others, and in our country - 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 mufflers for the most intense noise sources from:

steam emissions;

combined cycle plants;

draft machines (smoke exhausters and blowing 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 discharge of an energy boiler, the 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 mufflers is an urgent task. A silencer for noise emission of steam (silencer MEI) was developed.

The steam muffler has various modifications depending on the required emission noise reduction and the characteristics of the steam.

Currently, MPEI steam mufflers have been introduced at a number of energy facilities: Saransk combined heat and power plant No. 2 (CHPP-2) OJSC Territorial Generating Company-6, boiler OKG-180 OJSC Novolipetsk Metallurgical Plant, CHPP-9, CHPP-11 OJSC Mosenergo ". Steam consumption through the mufflers ranged from 154 t / h at Saranskaya CHPP-2 to 16 t / h at CHPP-7 of OAO Mosenergo.

MPEI mufflers were installed on the exhaust pipelines after the HPK boilers st. No. 1, 2 of CHPP-7 of CHPP-12 branch of OJSC "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 boilers st. No. 4, 5 of CHPP-9 of OAO Mosenergo, several MPEI mufflers were installed to discharge steam after the main safety valves(CPC). 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 counterparts, have high specific characteristics, allowing to achieve the maximum acoustic effect with a minimum muffler weight and maximum steam flow through the muffler.

MPEI steam mufflers can be used to reduce the noise of discharges into the atmosphere of superheated and wet steam, natural gas, etc. The design of the muffler can be operated in a wide range of parameters of the discharged steam and can be used both on blocks with subcritical parameters and on blocks with supercritical parameters. The experience of using MPEI steam mufflers has shown the necessary acoustic efficiency and reliability of the mufflers at various facilities.

When developing measures for noise suppression of gas turbine units, 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 gas paths of waste heat boilers of the following grades were made: KUV-69.8-150 produced by JSC Dorogobuzhkotlomash for the GTPP Settlement Severny, P-132 manufactured by JSC Podolsk Machine-Building Plant (JSC PMZ) for Kirishskaya GRES, P-111 manufactured by PMZ JSC for CHPP-9 of Mosenergo OJSC, waste heat boiler licensed by Nooter / Eriksen for the PGU-220 power unit of Ufimskaya CHPP-5, KGT-45 / 4,0- 430-13 / 0.53-240 for the Novourengoy gas chemical complex (MCC).

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

The GTU-CHPP "Severnyi Settlement" contains a double-casing KU designed by OJSC "Dorogobuzhkotlomash", which is installed after two FT-8.3 gas turbines manufactured by Pratt & Whitney Power Systems. Evacuation flue gas from the KU is carried out through one chimney.

The performed 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 plate noise muffler developed by MEI to reduce the exhaust noise of a gas turbine with a CD is located in two metal noise suppression ducts of the CD with dimensions of 6000x6054x5638 mm above the convection packs in front of the converters.

At the Kirishskaya GRES, a combined cycle gas turbine unit CCGT-800 with horizontal KU P-132 and GTU SGT5-400F (Siemens) is being implemented.

Calculations have shown that the required reduction of the noise level from the exhaust duct of the gas turbine unit is 12.6 dBA to ensure a sound level of 95 dBA at 1 m from the chimney mouth.

To reduce noise in the gas ducts 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 silencer consists of four cylindrical elements, evenly spaced in the chimney, while the relative flow area of ​​the silencer is 60%.

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

The use of mufflers to reduce noise from smoke exhausters on the example of CHPP-26 of JSC Mosenergo in horizontal sections is given in.

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

The lamellar noise muffler for the flue gas duct of the TGM CHPP-9 boiler is a two-stage design.

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

An example of a comprehensive study of measures for noise suppression is the development of MEI to reduce noise from smoke exhausters at HPP-1 of OAO Mosenergo. Here were presented high requirements to the aerodynamic resistance of the mufflers, 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, a branch of OAO Mosenergo, MPEI, has developed a whole noise suppression system. The noise damping system consists of the following elements: a lamellar muffler, lined with sound-absorbing material of turns of gas paths, a dividing sound-absorbing partition and a ramp. The presence of a dividing sound-absorbing partition, a ramp and a sound-absorbing lining of the turns of the gas ducts of boilers, in addition to reducing noise levels, helps to reduce the aerodynamic resistance of gas paths of power boilers st. No. 6, 7 as a result of the elimination of collision of flue gas streams at the point of their junction, the organization of smoother turns of flue gases in the gas ducts. Aerodynamic measurements showed that the total aerodynamic resistance of the gas paths of the boilers behind the smoke exhausters practically did not increase due to the installation of the noise suppression system. The total weight of the noise suppression system was about 2.23 tons.

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

PTVM-120 RTS "Yuzhnoye Butovo") and through the channels located in the wall of the boiler house (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 a 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 using sound-absorbing screens from four communication transformers of the ТЦ ТН-63000/110 ТЭЦ-16 ТЭЦ-16 brand of OAO Mosenergo. Sound-absorbing screens are installed at a distance of 3 m from the transformers. The height of each sound-absorbing baffle is 4.5 m, and the length varies from 8 to 11 m. The sound-absorbing baffle consists of separate panels installed in special racks. Steel panels with sound-absorbing cladding are used as screen panels. The panel is closed on the front side with a corrugated metal sheet, and on the transformer side - with a perforated metal sheet with a perforation rate of 25%. There is a non-flammable, non-hygroscopic sound-absorbing material inside the screen panels.

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

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

The active introduction of MPEI noise mufflers for hot water boilers continued. In the last 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, Novomoskovskaya, Babushkinskaya-1, Babushkinskaya-2, Krasnaya Presnya ", KTS-11, KTS-18, KTS-24 of Moscow, etc.

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

The introduction of MPEI mufflers continues.

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

The developed set of MPEI mufflers to reduce noise from various power equipment showed the required acoustic efficiency and takes into account the specifics of work at power facilities. The mufflers have undergone long-term operational testing.

The considered experience of their application allows us 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 facilities. SanPiN 2.2.1 / 2.1.1.567-01. M .: Ministry of Health of Russia, 2001.

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

3. The fight against noise in production / ed. E. Ya. Yudin. M .: Mechanical engineering. 1985 .-- 400 p.

4. Tupov VB Reducing noise from power equipment. M .: Publishing house MEI. 2005 .-- 232 p.

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

6. Tupov VB Noise from power equipment and ways to reduce it. In the tutorial: "Energy Ecology". M .: Publishing house MEI, 2003.S. 365-369.

7. Tupov VB Reducing noise from power equipment. Modern environmental technologies in the electric power industry: Information collection / ed. V.Ya. Putilova. M .: Publishing house MEI, 2007, pp. 251-265.

8. Marchenko M.E., Permyakov A.B. Modern systems noise suppression during discharge of large steam flows into the atmosphere // Teploenergetika. 2007. No. 6. S. 34-37.

9. Lukashchuk V.N. Noise during blowing 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 protection structures of turbine and boiler equipment: theory and calculation: diss. ... doc. those. sciences. SPb., 2004.398 p.

11. Silencer of noise emission of steam (options): Patent

for utility model 51673 RF. Application No. 2005132019. Appl. 10/18/2005 / V.B. Tupov, D.V. Chugunkov. - 4 p: ill.

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

13. Tupov V.B., Chugunkov D.V. The use of noise mufflers when discharging steam into the atmosphere / ULovoye in the Russian power industry. 2007. No. 12. Pp. 41-49

14. Tupov V.B., Chugunkov D.V. Silencers of noise on steam discharges from power boilers // Teploenergetika. 2009. No. 8. S.34-37.

15. Tupov V.B., Chugunkov D.V., Semin S.A. Reducing noise from exhaust ducts 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 air intakes of blowing fans of boilers // Teploenergetika. 2005. No. 5. S. 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. 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. Methods for reducing noise from hot water boilers RTS // Teploenergetika. 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 of noise reduction on the territory adjacent to CHPP-26 // Electric stations. 2004. No. 3. S. 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 energy-2004": Sat. report Moscow, VVTs, October 26-29, 2004 M., 2004.S. 152-154.

23. Tupov V.B. Experience of noise reduction of power plants / Y1 All-Russian scientific-practical conference with international participation "Protection of the population from increased noise exposure", March 17-19, 2009 St. Petersburg., S. 190-199.

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Due to the fact that noise at modern power plants, as a rule, exceeds permissible levels, in recent years, noise suppression work has been widely developed.
There are three main methods for reducing industrial noise: reducing noise at the source itself; reduction of noise along the path of its propagation; architectural and construction and planning solutions.
The method of noise reduction at the source of its occurrence is to improve the design of the source, to change the technological process. The most effective application of this method in the development of new power equipment. Recommendations for noise reduction at the source are given in § 2-2.
For soundproofing various premises power plants (especially the machine and boiler rooms) use construction solutions as the most noisy: thickening of the outer walls of buildings, the use of double-glazed windows, hollow glass blocks, double doors, multi-layer acoustic panels, sealing of windows, doors, openings, right choice air intake and exhaust points of ventilation units. It is also necessary to ensure good sound insulation between the machine room and basements, carefully sealing all openings and openings.
When designing the turbine room, avoid small spaces with smooth, sound-absorbing walls, ceilings, and floors. Wall cladding with sound absorbing materials (SPS) can reduce the noise level by about 6-7 dB in medium-sized rooms (3000-5000 m3). For large rooms, the efficiency of this method becomes controversial.
Some authors, such as G. Koch and H. Schmidt (Germany), as well as R. French (USA), believe that the acoustic treatment of the walls and ceilings of the station rooms is not very effective (1-2 dB). The data published by the French Energy Administration (EDF) indicate that this method of noise suppression is promising. The treatment of ceilings and walls in boiler rooms at the Saint-Depey and Chenevier power plants made it possible to obtain a sound reduction of 7-10 dB A.
At stations, separate soundproofed control rooms are often constructed, 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 in the machine rooms, acoustic cabins are installed to accommodate service personnel (electricians on duty, etc.). These soundproofing cabins represent an independent frame on supports, to which the floor, ceiling and walls are attached. Cab windows and doors must have increased sound insulation (double doors, double glazing). A ventilation unit with mufflers at the air inlet and outlet is provided for ventilation.
If it is necessary to have a quick exit from the cab, it is performed half-closed, that is, one of the walls is missing. At the same time, the acoustic efficiency of the cabin decreases, 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 individual cabins of a closed or semi-closed type in the premises of stations can be attributed to individual means protection of service 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 amounts to at least 20 dB. The disadvantages of these funds are that, along with noise, the level of useful signals, commands, etc. decreases, and skin irritation is also possible, mainly at elevated temperatures. environment... However, we recommend that you use earbuds and headphones when operating in excessive noise levels, especially in the high frequency range. Of course, it is advisable to use them for short-term exits from soundproofed cabins or control panels to areas of increased noise.

Acoustic screens are one of the ways to reduce noise along the paths of its propagation in the premises of the stations. Acoustic screens are made of sheet metal or other dense material, which can have sound-absorbing lining on one or both sides. Typically, acoustic baffles are small and provide local reductions in direct sound from the noise source without significantly affecting the reflected sound level 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 design point. An increase in the acoustic efficiency of screens can be achieved by increasing their area, which should be at least 25-30% of the cross-sectional area of ​​the room fences in the plane of the screen. In this case, the efficiency of the screen increases due to a decrease in the energy density of the reflected sound in the screened part of the room. The use of large screens can also significantly increase the number of workplaces where noise reduction is ensured.

The most effective application of screens together with the installation of sound-absorbing facings on the enclosing surfaces of the premises. A detailed description of the methods for calculating the acoustic efficiency and issues of designing screens is given in and
To reduce noise in the entire machine room, units emitting intense sound are encased. Soundproof enclosures are usually made of sheet metal lined with inside ZPM. The surfaces of the units can be completely or partially sheathed with sound-insulating material.
According to the data given by American sound attenuation specialists at the International Conference on Energy in 1969, the complete equipping of high-power turbine units (500-1000 MW) with sound-insulating casings makes it possible to reduce the level of radiated sound by 23-28 dB A, while placing the turbine units in special insulated boxes, the 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 in the United States after 1971, it is distributed as follows: aluminum -30%, sheet steel - 27%, gelbest-18%, asbestos-cement - 11%, brick-10%, porcelain with an outer coating - 9%, concrete - 4%.
In national teams acoustic panels the following materials are used: sound insulating - steel, aluminum, lead; sound-absorbing foam, mineral wool, fiberglass; damping - bituminous compounds; sealing - rubber, putty, plastics.
Polyurethane foam, fiberglass, sheet lead, vinyl reinforced with lead powder are widely used.
To reduce the noise of the brush apparatus and exciters of high-power turbine units, the Swiss company BBC covers them with a solid protective cover with a thick layer of sound-absorbing material, in the walls of which silencers are integrated at the inlet and outlet of the cooling air.

The structure of the cladding provides free access to these units for routine repairs. As shown by the research of this company, the sound-insulating effect of the turbine front sheathing 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 GTU body of the GTK-10-Z type
1- with a decorative cover; 2- with the body removed

Particular attention should be paid to sound insulation at 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 four gas turbine engines are located 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 installations, it is more economical to place them in a common building. For example, Westinghouse is installing five 501-AA gas turbines in one acoustically insulated building.

Typically for individual boxes, sheet metal panels are used, with sound-absorbing cladding on the inside. The sound-absorbing cladding can be made of mineral wool or semi-rigid mineral wool slabs in a glass cloth sheath and covered from the side of the noise source with a perforated sheet or metal mesh... The panels are connected to each other with bolts, at the joints - elastic gaskets.
Multilayer panels made of internal perforated steel and external lead sheets used abroad are very effective, between which a porous sound-absorbing material is placed. Panels with multi-layer are also used. 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 sound insulating cladding provides a significant reduction in the background noise in the engine rooms. In fig. 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 the GTK-10-3 type gas-pumping unit. For comparison, the same figure shows the 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 with a thickness of 1 mm, lined inside with a glass fiber with a thickness of 10 mm, is 10-15 dB in the high-frequency region of the spectrum. The measurements were carried out in a workshop built according to a standard design, where 6 GTK-10-3 units were installed, covered with decorative cladding.
Sound insulation of pipelines is a common and very important problem for energy enterprises of any type. 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 Kirkhleigeri TPP: a - insulation diagram; b - components of a multilayer panel
1- metal cladding made of sheet steel; 2- mats made of stone wool 20 mm thick; 3- aluminium foil; 4- multilayer panel 20 mm thick (weight I m2 is 10.5 kg); 5- bitumen felt; 6- layers of thermal insulation; 7- foam layer

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

To reduce the noise of pipelines transporting highly disturbed flows (for example, in areas behind the pressure reducing valves), enhanced sound insulation can be recommended, shown in Fig. 2-11.
The sound insulating effect of such a coating is about 30 dB A (reduction of the sound level compared to a “bare” pipeline).
For lining pipelines large diameter multilayer heat and sound insulation is used, which is reinforced with ribs and hooks welded to the insulated surface.
The insulation consists of a 40-60 mm thick layer of mastic covelite insulation, on top of which a 15-25 mm thick armor wire mesh is laid. The mesh serves to strengthen the sovelite 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 6-7 grades and 20% cement grade 300). This layer is covered (pasted over) with some kind of technical fabric. If necessary, the surface is painted. This method of soundproofing using previously available thermal insulation elements can significantly reduce noise. The additional costs associated with the introduction of new soundproofing elements are negligible compared to conventional thermal insulation.
As already noted, the most intense aerodynamic noise arising from the operation of fans, smoke exhausters, gas turbine and steam-gas installations, relief devices (blowdown lines, safety lines, lines of anti-surge valves of gas turbine compressors). This also includes ROU.

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 play an important role in common system measures to reduce noise at power plants, because through intake or exhaust devices, sound from working cavities can be directly transmitted into the surrounding atmosphere, creating the highest levels of sound pressure (in comparison with other sources of sound emission). It is also useful to limit the propagation of noise through the conveyed medium in order to prevent its excessive penetration through the walls of the pipeline to the outside by installing noise suppressors (for example, a section of the pipeline behind a pressure reducing valve).
On modern powerful steam turbine units, sound attenuators are installed at the inlet of 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 mufflers is usually 15 to 25 dB in the range of the spectrum from 200 to 1000 Hz in terms of the installation effect.
For example, at the Robinson TPP (USA) with a capacity of 900 MW (two blocks of 450 MW each), to reduce the noise of blowing fans with a capacity of 832,000 m3 / h, suction mufflers are installed. The muffler consists of a body (steel sheets 4.76 mm thick), in which a grill 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.
Coppers manufactures standard noise suppressing units used in fan silencers used for drying pulverized coal, air supply to boiler burners, and room ventilation.
The noise of smoke exhausters is often a significant hazard, since it can escape into the atmosphere through the chimney and spread over considerable distances.
For example, at the Kirchlengern TPP (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, a length of 7.5 m. supporting structure... The curtain consists of a body made of sheet steel and an absorber (mineral wool), protected by fiberglass. After installing the muffler, the sound level at the chimney was 89 dB A.
The complex task of noise reduction in a gas turbine plant requires an integrated approach. Below is an example of a set of measures to combat the noise of a gas turbine unit, an essential part of which are silencers in the gas-air ducts.
To reduce the noise level of the GTU with the Olympus 201 turbojet engine with a capacity of 17.5 MW, an analysis of the required degree of noise suppression of the unit 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 for the attenuation of the suction noise of the gas turbine unit by various elements (dB):

Average geometric frequency of the octave band, Hz ........................................					1000 2000 4000 8000
Sound pressure levels at a distance of 90 m from the suction of the gas turbine unit to noise suppression ...................................... .............
Attenuation in an unfaced turn (knee) 90 ° ................................
Attenuation in a veneered bend (knee) at 90 ° .................................
Attenuation due to air filter. ... ... . · ................................................ .........
Attenuation by louvers ..............
Attenuation in the high-frequency part of the muffler ............................................. ...
Attenuation in the low-frequency part of the muffler ............................................. ................
Sound pressure levels at a distance of 90 m after soundproofing ....

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

Average geometric frequency of the octave band, Hz ........
Sound pressure level, dB: before installing the muffler. ... ...
after installing the muffler. ...

To reduce noise and vibrations, the gas generator of the GTU 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-power gas turbines, air intake mufflers are often very cumbersome and complex engineering structures. An example is the noise suppression system at the Var gas turbine CHPP (Germany), where two Brown-Boveri gas turbines with a capacity of 25 MW are installed.

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

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

The station is located in the central part of the populated area. A muffler is installed at the intake of the gas turbine unit, which consists of three successively located stages. The sound-absorbing material of the first stage, designed to damp low-frequency noise, is mineral wool covered 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
comprises 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 on a number of powerful domestic installations, for example, at the Krasnodarskaya TPP (GT-100-750), Nevinnomysskaya TPP (PGU-200). Their construction is described 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 GTU 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 time consuming. Therefore, the issues of optimizing the designs of noise suppressors are of particular importance, which is impossible without knowledge of the most advanced calculation methods and the theoretical basis of these methods.

Date: 12.12.2015

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

How to reduce the noise of a boiler room during design

Very strict requirements are imposed on the noise level of electrical 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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