CN103968364A

CN103968364A - Method and device for controlling noise in waste heat boiler

Info

Publication number: CN103968364A
Application number: CN201410144246.6A
Authority: CN
Inventors: 赵迎九; 黄福安; 钟振茂; 任玉凤; 魏普; 余平覆; 王奇
Original assignee: Huadian Heavy Industries Co Ltd
Current assignee: Huadian Heavy Industries Co Ltd
Priority date: 2013-12-24
Filing date: 2014-04-11
Publication date: 2014-08-06
Anticipated expiration: 2034-04-11
Also published as: CN103968364B; CN103742893A

Abstract

The invention discloses a method and device for controlling noise in a waste heat boiler. The method comprises the steps that flow noise produced by pipe array vortex shedding is eliminated by a perforated sound absorber and transmission of the noise in a boiler chamber to a chimney is reduced by a resonance type silencer, wherein the perforated sound absorber is formed by attaching two perforated plates to the two sides of a liner plate respectively, the resonance type silencer is composed of double-faced perforated sound absorbing plates and single-faced sound absorbing structures, and the double-faced perforated sound absorbing plates and the single-faced sound absorbing structures are arranged in the boiler chamber. The resonance type silencer has the better low-frequency silencing performance, noise transmitted from a chimney opening has the noise reduction amount of 14 dB(A) on an octave band of 63 Hz, and noise at the boundary of an enterprise nearly reaches a production standard. The perforated sound absorber can effectively absorb the noise produced by the inner portion of the waste heat boiler and a part of the noise is reflected to a noise source. In addition, compared with the prior art, the noise reduction investment cost is reduced by at least 1/3.

Description

The control method of waste heat boiler internal noise and device

Technical field

The present invention relates to a kind of control method and device of waste heat boiler internal noise, belong to the noise management technique field of waste heat boiler.

Background technology

Thereby waste heat boiler can carry out the waste heat producing after fuel gas generation secondary utilization and improve generating efficiency, thereby makes waste heat boiler more and more extensive in the application of power field.But waste heat boiler can produce a large amount of noises in the process using, and has had a strong impact on periphery resident's work and life, therefore, wants to utilize for a long time waste heat boiler to generate electricity again, must carry out noise reduction process to it.Find by the noise monitoring to waste heat boiler, the acoustic radiating of chimney has the greatest impact to sensitive spot outside factory.

At present, for the noise reduction process of waste heat boiler, owing to cannot finding out the root of waste heat boiler noise, so mostly just by adopting boiler close-fitting vest to go along with sb. to guard him, (or silencer box, as the application number disclosed combined soundproofing box for combustion machine set of fuel-oil and gas-fired boiler of patent application that is 97108129.8), boiler body is wrapped, stop the sonic propagation of making an uproar, but this mode can not reach the object of effective noise reduction, boiler close-fitting vest is set simultaneously and goes along with sb. to guard him not only with high costsly, but also be unfavorable for the heat radiation of boiler furnace, the performance of boiler itself is caused to very large impact; The daily maintenance of boiler and maintenance are also brought to a lot of inconvenience.In addition, application number be 02224882.X Patent Application Publication a kind of oil-burning gas-fired boiler chimney silencer, application number is 03146988.4 to disclose a kind of Steel-made chimney noise treating method for power plant, but all there is following shortcoming in above scheme: be installed on chimney outside, the holding capacity that makes chimney is large and have a strong impact on the discharge performance of chimney; Do not carry out noise reduction for the low-frequency noise of boiler noise contribution amount maximum, the noise reduction of entirety is general; Structure is fixed, poor for applicability, is of limited application.Therefore, how providing the recognition methods in a kind of boiler noise source and the low cost noise-reduction method of chimney discharge noise is current urgent problem.

Summary of the invention

The object of the invention is to, a kind of control method and device of waste heat boiler internal noise are provided, it can effectively solve problems of the prior art, especially cannot find out the root of waste heat boiler noise and carry out noise reduction targetedly, thereby cause the general and higher problem of cost of noise reduction.

For solving the problems of the technologies described above, the present invention adopts following technical scheme: a kind of control method of waste heat boiler internal noise, adopts perforation sound absorber to eliminate the flow noise of pipe battle array vortex shedding; Adopt resonator muffler to reduce furnace chamber noise and propagate to chimney, described furnace chamber noise mainly comprises the sympathetic response amplification noise that the pipe battle array flow noise of vortex shedding and the flow noise of this pipe battle array vortex shedding and its corresponding normal frequency sound wave exciting in furnace chamber form; The both sides that described perforation sound absorber fits in respectively liner plate by two perforated plates form, and described resonator muffler is made up of double-sided perforated acoustic board and the one side sound absorption structure of being located at furnace chamber inside.

When the present invention adopts perforation sound absorber to eliminate the flow noise of pipe battle array vortex shedding, this perforation sound absorber is arranged in the cavity between exchanging pipe of boiler by waste layer.

Preferably, while adopting perforation sound absorber to eliminate the flow noise of pipe battle array vortex shedding, this perforation sound absorber is arranged on the diagonal of the cavity between exchanging pipe of boiler by waste layer and vertical with horizontal plane.

When the present invention adopts resonator muffler minimizing furnace chamber noise to propagate to chimney, this resonator muffler is installed in the chimney of waste heat boiler and the cone space of furnace chamber junction.

Preferably, while adopting resonator muffler minimizing furnace chamber noise to propagate to chimney, the double-sided perforated acoustic board of this resonator muffler is arranged in the chimney of waste heat boiler and the cone space of furnace chamber junction, and one side sound absorption structure is arranged on the inwall of cone space; In cone space, double-sided perforated acoustic board is arranged side by side and perpendicular to horizontal plane along the direction of flow of flue gas with the spacing of fixing.

The sympathetic response that the flow noise of described pipe battle array vortex shedding and the flow noise of this pipe battle array vortex shedding and its corresponding normal frequency sound wave exciting in furnace chamber form is amplified noise and is identified by the following method acquisition:

S1, sets up naked pipe two dimensional model, simulation calculation high-pressure superheater and flow field and sound field except naked pipe under two Guan Zhen of oxygen evaporator respectively, and calculate segmentation feature frequency, estimate the characteristic frequency region of entirety in stove;

S2, sets up extended surface tube FEM model, distinguishes simulation calculation high-pressure superheater and removes extended surface tube single tube flow field and the sound field under two Guan Zhen of oxygen evaporator, and calculating segmentation feature frequency, estimates the characteristic frequency region of entirety in stove;

S3, by the characteristic frequency of contrast extended surface tube and naked pipe, adopts the correction means of percentage side-play amount to revise the characteristic frequency of Guan Zhen;

S4, calculate normal frequency, according to the distribution of the distribution of each layer normal frequency and each layer of characteristic frequency, judge whether to excite normal frequency and produce the operatic tunes resonate;

S5, carries out sound transmission loss and oise insulation factor calculating to boiler, and obtains overall noise in boiler in conjunction with actual measurement noise data;

S6, comparative analysis is also calculated the contribution amount of variety classes noise to noise in stove, determines the main source of noise in stove.

Preferably, in step S1 and S2, Flow Field Calculation adopts LES; Sound field is calculated the FWH method that adopts.

In step S1, while calculating the segmentation feature frequency of high-pressure superheater, the limit wall condition of the computation model of employing is periodic boundary condition, ensures the continuous of left and right, flow field wall speed and vorticity; Computation model has symmetrical property.

In step S2, while calculating the segmentation feature frequency of removing oxygen evaporator, the limit wall condition of the computation model of employing is periodic boundary condition; Computation model has symmetrical property.

Concrete, in step S5, by the following method boiler is carried out to the calculating of furnace chamber sound transmission loss: set up operatic tunes FEM model and import Virtual lab, corresponding gas medium parameter is set, entrance boundary condition is made as plane wave, and export boundary condition is made as ature of coal impedance, resolution ratio 10Hz, do the frequency sweep of 20～2000Hz frequency range, according to the entrance acoustic pressure calculating and outlet acoustic pressure, calculate with sound transmission loss definition, obtain the sound transmission loss curve of the operatic tunes; The sound transmission loss of each pipe layer is directly superposeed, estimate the sound transmission loss of whole furnace chamber.

In preceding method, the oise insulation factor of described boiler is TL, TL=20lg ω+20lg (M ₁+ M ₂+ M ₃)-10lg4R ₃ ², wherein, R3 is boiler extraneous air acoustic impedance, unit is N*s/m ³, M ₁, M ₂, M ₃be respectively the surface density of lining steel plate, hull plate, heat-insulation layer, unit is kg/m ².

Concrete, whether step S6 comprises: calculate the each interval noise grade A of boiler body and fire machine exhaust noise in the A of boiler body inside sound level, judging in stove and have regenerated noise to produce; If generation regenerated noise, just according to the extended surface tube noise spectrum of simulation calculation, can estimate the flow noise octave spectrum of pipe layer, itself and boiler body regenerated noise are contrasted: according to result of calculation, further in analytical furnace, noise Middle combustion engine exhaust noise, with managing the contribution amount of battle array vortex shedding flow noise at different frequency range, is determined noise source in waste heat boiler.

Preferably, the contribution amount of computer tube battle array vortex shedding flow noise by the following method:

(1) suppose combustion machine exhaust noise harmless propagation in horizontal flue, calculate A sound level according to its sound power level, entirely provided by the exhaust of combustion machine because noise in horizontal flue is approximate, so the noise grade A using combustion machine exhaust noise A sound level in horizontal flue, by the noise grade A in horizontal flue and the actual oise insulation factor that calculates horizontal flue at the noise grade A of horizontal flue external pelivimetry; Heat-insulation layer and the horizontal flue of boiler body are suitable, and theoretical calculating oise insulation factor is approaching, therefore can be similar to the actual oise insulation factor of using horizontal flue as the actual oise insulation factor of boiler body; Calculate the noise grade A in boiler according to the measured data outside boiler body and actual oise insulation factor again;

(2) obtain the A sound level of pipe battle array vortex shedding flow noise and obtain the contribution amount of pipe battle array noise by simulation compared with noise grade A in boiler.

The present invention calculates the contribution amount of combustion machine exhaust noise by the following method:

(1) insulation construction of boiler body and horizontal flue approaches, and theoretical oise insulation factor is suitable, actual oise insulation factor by the actual oise insulation factor of horizontal flue as boiler body, calculates the noise grade A in boiler according to the measured data outside boiler body and actual oise insulation factor;

(2) suppose combustion machine exhaust noise harmless propagation in horizontal flue, calculate combustion machine exhaust noise and import into the noise grade A of boiler body according to the acoustical power of combustion machine exhaust noise, and the contribution amount that it is obtained firing machine exhaust noise compared with noise grade A in boiler.

The control device (being resonator muffler) of realizing the waste heat boiler internal noise of preceding method, is made up of double-sided perforated acoustic board and the one side sound absorption structure of being located at furnace chamber inside; Described double-sided perforated acoustic board is located at furnace chamber inside side by side, and is made up of the perforation sound absorber stack of polylith different resonant frequencies; Described perforation sound absorber comprises: two perforated plates and a liner plate, and two perforated plates fit in respectively the both sides of liner plate; The both sides that liner plate is close to perforated plate are trench structure, make to form sound absorption cavity between perforated plate and liner plate, and perforation place on perforated plate is provided with internal lining pipe; Described one side sound absorption structure is located on the inwall on waste heat boiler top.

Preferably, described one side sound absorption structure comprises: a perforated plate and a liner plate, and perforated plate fits in a side of liner plate, and liner plate one side of being close to perforated plate is trench structure, makes formation sound absorption cavity between perforated plate and liner plate.

Preferably, the thickness of described perforated plate is 1～2mm, and aperture is 3～5mm, and punching rate is 0.25%～0.35%; Longitudinal degree of depth of described cavity is 200～230mm; The length of described internal lining pipe is 7～8mm, thereby when this perforation sound absorber is used for to waste heat boiler, perforation sound absorber has at the centre frequency place of 80Hz the acoustic absorptivity that exceedes 0.9, and 1/2 maximum acoustic absorptivity all reaches two third-octaves, can effectively eliminate the flow noise of pipe battle array vortex shedding.

Preferably, the thickness of described perforated plate is 2mm, and aperture is 10～13mm, and punching rate is 0.4%～0.55%; Longitudinal degree of depth of described cavity is 200mm; The length of described internal lining pipe is 7mm, thereby while forming resonator muffler, can effectively eliminate the flow noise of pipe battle array vortex shedding and amplify noise with the sympathetic response that the corresponding normal frequency sound wave that it excites in furnace chamber forms.

In the present invention, the spacing between adjacent two double-sided perforated acoustic boards is 0.5～2 meter; The height of double-sided perforated acoustic board is 1.0～5 meters; Described double-sided perforated acoustic board is made up of 3～8 different perforation sound absorber stacks of resonant frequency.

Preferably, the spacing between adjacent two double-sided perforated acoustic boards is 1 meter, and the height of double-sided perforated acoustic board is 2 meters; Double-sided perforated acoustic board is made up of 4 different perforation sound absorber stacks of resonant frequency, the plate hight of every perforation sound absorber is 0.5m, thereby when this resonator muffler is used for to waste heat boiler, there is good low frequency acoustic attenuation performance, can effectively eliminate the flow noise of pipe battle array vortex shedding and amplify noise with the sympathetic response that the corresponding normal frequency sound wave that it excites in furnace chamber forms, the noise that throat is discharged has the sound deadening capacity of 14dB (A) on the octave band of 63Hz, and Shi Chang circle noise reaches discharge standard substantially.

Advantage of the present invention:

1. the present invention is by setting up naked pipe two dimensional model and extended surface tube FEM model, estimate respectively the characteristic frequency region of entirety in stove, and by contrasting two characteristic frequencies, the characteristic frequency of Guan Zhen is revised, judge whether to produce operatic tunes resonance by calculating normal frequency, again boiler is carried out to sound transmission loss and oise insulation factor calculating, and obtain overall noise in boiler in conjunction with actual measurement noise data, by comparative analysis, calculate the contribution amount of variety classes noise to noise in stove, determine the main source of noise in stove.

2. adopt UG to set up geometrical model+Hypermesh pre-treatment+Fluent calculating and arrange in pairs or groups with the software of post processing, there is higher confidence level.Wherein, the calculating of the transient flow field of core and sound field are calculated the large eddy simulation (LES) and the FW-H method that adopt respectively in Fluent.Large eddy simulation, by filtering processing, first filters out the vortex that is less than certain yardstick from flow field, only calculates large whirlpool, then obtains the solution in little whirlpool by solving additional equation.Filter yardstick and be generally taken as mesh scale.This method is higher than direct Numerical (DNS) efficiency, and consume system resources still less, more accurate than Reynolds average (RANS) method.The in the situation that of known flow field information, use FW-H equation that the active force in flow field is equivalent to monopole, dipole and quadrapole source and carry out noise simulation, because this calculating belongs to the mobile effect that can ignore monopole and quadrapole source of low mach, and Fluent processes like this.Large eddy simulation (LES) combines with FW-H equation, efficiently and accurately the information of flow of computer tube battle array (vortex shedding) harmony field information (characteristic frequency).Approximate, the pipe battle array partial simplified of model and the precision of computing grid of flue gas thermodynamics information have all been taken into account operational precision and efficiency under the prerequisite that meets physics reality, have good applicability.

3. the method for the invention has been considered waste heat boiler internal environment specifically, all sidedly, compares existing Noise Sources Identification method and more tallies with the actual situation; Can find out the main contributions person of boiler noise, make noise reduction measure design have more specific aim.The resonator muffler designing as basis taking the furnace interior noise source of the method for the invention Analysis deterrmination, can reduce waste heat boiler noise pollution better, saves noise reduction cost.

4. the perforation sound absorber for waste heat boiler of the present invention, by internal lining pipe and a large amount of apertures are set on perforated plate, thereby effectively avoid traditional sound-absorbing porous material to hold susceptible to plugging problem, and the cavity that perforated plate and liner plate form formed resonance absorber jointly, can effectively absorb the inner noise producing of waste heat boiler and a part of noise is reflected back to noise source.The present invention uses perforated plate design theory, according to the operating condition design of difference pipe layer meet the perforation sound absorber of this condition of low frequency and narrow bandwidth, perforation sound absorber has at the centre frequency place of 80Hz the acoustic absorptivity that exceedes 0.9, and 1/2 maximum acoustic absorptivity all reaches two third-octaves.Show according to mass data statistics, adopt after perforation sound absorber of the present invention, the noise of waste heat boiler inside can reduce by 14 decibels.In analytical furnace of the present invention, the propagation law of noise normal mode, has realized effective setting of sound absorber; The present invention is arranged at perforation sound absorber on the diagonal of the cavity between exchanging pipe of boiler by waste layer and is vertical with horizontal plane, and compared with being arranged at other positions, its noise reduction rate has improved 5%.

5. show after deliberation, the simple vibration frequency that each pipe layer of waste heat boiler produces is not identical, the come off frequency of noise of the eddy current that the present invention is directed to different pipe layers has been carried out corresponding design to the structural parameters of perforation sound absorber, thereby can effectively absorb the regenerated noise of each pipe layer.

6. the present invention by installing resonator muffler in the chimney of waste heat boiler and the cone space of furnace chamber junction, the polylith double-sided perforated acoustic board that this resonator muffler is arranged side by side by polylith forms, double-sided perforated acoustic board is made up of the different polylith perforation sound absorber stack of structural parameters again, thereby the double-sided perforated acoustic board resonant frequency that effectively staggered, widened noise elimination frequency band simultaneously, thus the impact of the acoustic radiating that has reduced chimney on sensitive spot outside factory; Resonator muffler of the present invention has good low frequency acoustic attenuation performance, and the noise that can make throat discharge has the sound deadening capacity of 14dB (A) on the octave band of 63Hz, and Shi Chang circle noise reaches discharge standard substantially.Show according to mass data statistics, adopt after resonator muffler of the present invention, in resonance band, the reducing noise of throat 14 decibels, the reducing noise of factory circle 8.9 decibels.

7. resonator muffler of the present invention is arranged on boiler internal, not only can effectively reduce the holding capacity of chimney, and its flexible structure, is suitable for applying widely.

8. adopt resonator muffler of the present invention and perforation sound absorber for waste heat boiler noise reduction, with respect to prior art, the noise reduction cost of its input has at least reduced by 1/3.

Brief description of the drawings

Fig. 1 is the scheme of installation for the resonator muffler of waste heat boiler;

Fig. 2 is the structural representation for the resonator muffler of waste heat boiler;

Fig. 3 is the structural representation of perforation sound absorber;

Fig. 4 is the profile for the perforation sound absorber of waste heat boiler;

Fig. 5 is the structural representation of liner plate;

Fig. 6 adopts the double-sided perforated acoustic board of combination parameter and the sound deadening capacity comparison diagram of the double-sided perforated acoustic board of employing single parameter;

Fig. 7 is the equivalent circuit diagram for the perforation sound absorber of waste heat boiler;

Fig. 8 is the acoustically effective figure of the perforation sound absorber of different pipe layers;

Fig. 9 is the method to set up overall schematic of perforation sound absorber of the present invention;

Figure 10 is the method to set up profile of perforation sound absorber of the present invention;

Figure 11 is the profile of one side sound absorption structure.

Reference numeral: 1-double-sided perforated acoustic board, the 2-sound absorber of boring a hole, 3-perforated plate, 4-liner plate, 5-cavity, 6-furnace chamber, 7-chimney, 8-internal lining pipe, 9-one side sound absorption structure.

Below in conjunction with the drawings and specific embodiments, the present invention is further illustrated.

Detailed description of the invention

Embodiments of the invention 1: a kind of control method of waste heat boiler internal noise, comprising:

(1) adopt perforation sound absorber to eliminate the flow noise of pipe battle array vortex shedding, in the time eliminating the flow noise of pipe battle array vortex shedding, this perforation sound absorber is arranged on the diagonal of the cavity between exchanging pipe of boiler by waste layer and vertical with horizontal plane;

Described perforation sound absorber 2(is as shown in Fig. 3～Fig. 5) comprising: two perforated plates 3 and 4, two perforated plates 3 of a liner plate fit in respectively the both sides of liner plate 4; The both sides that liner plate 4 is close to perforated plate 3 are trench structure, make to form sound absorption cavity 5 between perforated plate 3 and liner plate 4, and perforation place on perforated plate 3 is provided with internal lining pipe 8; Concrete, be arranged at the perforation sound absorber 2 in the high-pressure superheater top cavity of waste heat boiler, the thickness of described perforated plate 3 is 1mm, and aperture is 5mm, and punching rate is 0.25%; Longitudinal degree of depth of described cavity 5 is 230mm; The length of described internal lining pipe 8 is 7mm; Be arranged at the perforation sound absorber 2 in the high pressure evaporator top cavity of waste heat boiler, the thickness of described perforated plate 3 is 1mm, and aperture is 4mm, and punching rate is 0.30%; Longitudinal degree of depth of described cavity 5 is 230mm; The length of described internal lining pipe 8 is 7mm; Be arranged at the perforation sound absorber 2 in the low pressure evaporator top cavity of waste heat boiler, the thickness of described perforated plate 3 is 2mm, and aperture is 3mm, and punching rate is 0.30%; Longitudinal degree of depth of described cavity 5 is 200mm; The length of described internal lining pipe 8 is 7mm; Be arranged at the perforation sound absorber 2 in the high-pressure economizer top cavity of waste heat boiler, the thickness of described perforated plate 3 is 2mm, and aperture is 4mm, and punching rate is 0.30%; Longitudinal degree of depth of described cavity 5 is 200mm; The length of described internal lining pipe 8 is 7mm; Be arranged at the perforation sound absorber 2 in the low-pressure superheater top cavity of waste heat boiler, the thickness of described perforated plate 3 is 2mm, and aperture is 4mm, and punching rate is 0.30%; Longitudinal degree of depth of described cavity 5 is 220mm; The length of described internal lining pipe 8 is 7mm; Be arranged at the perforation sound absorber 2 in the high-pressure economizer top cavity of waste heat boiler, the thickness of described perforated plate 3 is 2mm, and aperture is 3mm, and punching rate is 0.30%; Longitudinal degree of depth of described cavity 5 is 200mm; The length of described internal lining pipe 8 is 7mm; The perforation sound absorber 2 in the cavity of oxygen evaporator top that removes that is arranged at waste heat boiler, the thickness of described perforated plate 3 is 2mm, and aperture is 3mm, and punching rate is 0.35%; Longitudinal degree of depth of described cavity 5 is 200mm; The length of described internal lining pipe 8 is 7mm;

(2) adopting resonator muffler to reduce furnace chamber noise propagates to chimney; Described furnace chamber noise mainly comprises the sympathetic response amplification noise that the pipe battle array flow noise of vortex shedding and the flow noise of this pipe battle array vortex shedding and its corresponding normal frequency sound wave exciting in furnace chamber form; While adopting resonator muffler minimizing furnace chamber noise to propagate to chimney, the double-sided perforated acoustic board 1 of this resonator muffler is arranged in the chimney of waste heat boiler and the cone space of furnace chamber junction, and double-sided perforated acoustic board 1 is arranged and perpendicular to horizontal plane along the direction of flow of flue gas is parallel with the spacing of fixing; The one side sound absorption structure 9 of this resonator muffler is arranged on the inwall of cone space.

Described resonator muffler, as shown in Fig. 1～Fig. 5, Figure 11, is made up of double-sided perforated acoustic board 1 and the one side sound absorption structure 9 of being located at furnace chamber inside; Described double-sided perforated acoustic board 1 is located at furnace chamber inside side by side, and is made up of perforation sound absorber 2 stacks of polylith different resonant frequencies; Described perforation sound absorber 2 comprises: two perforated plates 3 and 4, two perforated plates 3 of a liner plate fit in respectively the both sides of liner plate 4; The both sides that liner plate 4 is close to perforated plate 3 are trench structure, make to form sound absorption cavity 5 between perforated plate 3 and liner plate 4, and perforation place on perforated plate 3 is provided with internal lining pipe 8; Described one side sound absorption structure 9 is located on the inwall on waste heat boiler top; Described one side sound absorption structure 9 comprises: a perforated plate 3 and a liner plate 4, and perforated plate 3 fits in a side of liner plate 4, and liner plate 4 one sides of being close to perforated plate 3 are trench structure, make formation sound absorption cavity 5 between perforated plate 3 and liner plate 4.Spacing between adjacent two double-sided perforated acoustic boards 1 is 1 meter, and the height of double-sided perforated acoustic board 1 is 2 meters, and double-sided perforated acoustic board 1 is made up of 4 different perforation sound absorber 2 stacks of resonant frequency, and the plate hight of every perforation sound absorber 2 is 0.5m; The thickness of perforated plate 3 is 2mm, and aperture is 10～13mm, and punching rate is 0.4%～0.55%; Longitudinal degree of depth of described cavity 5 is 200mm; The length of described internal lining pipe 8 is 7mm.

Experimental example 1: the perforation sound absorber for waste heat boiler of the present invention, form by wearing with the perforated plate of a large amount of apertures and with the cavity 5 that liner plate 4 forms, it is resonance absorber, can regard the acoustic element with acoustic resistance and acoustic reactance as, it is constructed as shown in Figure 3, Figure 4, equivalent circuit as shown in Figure 7, in Fig. 7, R, M are respectively acoustic resistance and the acoustic mass of perforated plate, Z _dfor the acoustic capacitance of cavity after plate 5, the specific acoustic impedance of perforated plate 3 is R+jwM, and the specific acoustic impedance of cavity is Z _{s cavity}, sound source is incident acoustic wave, according to Thevenin law, equivalent source is acoustic pressure and the internal impedance of open circuit (stream is zero, before the surface of solids), i.e. 2P, ρ ₀c ₀.

Can obtain acoustic absorptivity α according to equivalent circuit, the ratio of the energy consuming in circuit and the energy of incident (or ceiling capacity), in the time of normal incidence, acoustic absorptivity equals:

Z _{s is total}=R+jwM+Z _{s cavity}=R _{s is total}+ jX _{s is total}

Known according to above-mentioned theory: the key of the present invention's design is according to noise characteristic coupling the specific acoustic impedance of calculation punch plate and the specific acoustic impedance of cavity.Because pending noise has obvious low frequency, narrow-band characteristic (characteristic frequency is at 74Hz～78Hz), adopt resonant noise elimination structure without considering too much bandwidth, in ensureing low frequency absorbability, need to take into account less space hold rate (avoiding affecting flowing of flue gas).And the perforation sound absorber 2 of the present invention's design, the structure of employing perforated plate 3 and rectangle backing, calculates through theory, has good low frequency absorption characteristic and space availability ratio.

The sound absorption characteristics of perforation sound absorber of the present invention adopt following methods to calculate:

First, according to electro-acoustical analogy principle, the equivalent circuit of the sound absorber of boring a hole while making sound wave vertical incidence;

Then try to achieve the specific acoustic impedance of perforated plate 3 and cavity 5 according to (micro-) perforated plate sound absorber theory;

Finally, draw acoustic absorptivity according to the relation of equivalent acoustic impedance rate and acoustic absorptivity.

Comprise specifically following content:

The accurate calculating formula of considering the thin short pipe specific acoustic impedance of air viscous drag is:

Z_{1} = \frac{Δp}{\overset{&OverBar;}{u}} = jw ρ_{0} t {[1 - \frac{2}{\sqrt{- jk}} \frac{J_{1} (\sqrt{- j} k)}{J_{0} (\sqrt{- j} k)}]}^{- 1}

In formula, for perforated plate constant, ρ ₀for gas density, μ is gas viscosity coefficient, and t is pipe length, and d is pipe diameter;

Deriving unified specific acoustic impedance approximate expression according to the approximate expression in k < 1 and 10 two kinds of situations of k > is:

Z_{1} = \frac{32 μt}{d^{2}} \sqrt{1 + \frac{k^{2}}{32}} + jw ρ_{0} t [1 + {(3^{2} + \frac{k^{2}}{2})}^{- 1 / 2}]

Can prove that approximate expression and accuracy type meet fine, satisfied k value arbitrarily and error are less than 6%.

On this basis, consider the correction of impact, specific acoustic resistance and the specific acoustic reactance of punching rate σ, on plate face, fricative specific acoustic resistance is the piston transmitting at tubule two ends equals pipe range increases 0.85d.Two close, and the relative sound impedance of known perforated plate or unit area impedance ratio become:

z＝r+jwm，

Wherein,

\frac{32 ηt}{{σρ}_{0} c_{0} d^{2}} k_{r},

k_{r} = \sqrt{1 + \frac{k^{2}}{32}} + \frac{\sqrt{2}}{8} k \frac{d}{t};

\frac{wt}{σ c_{0}} k_{m},

k_{m} = 1 + {(3^{2} + \frac{k^{2}}{2})}^{- 1 / 2} + 0.85 \frac{d}{t},

In formula, wherein, f is sound frequency, and d is the aperture of perforated plate, and z is relative sound impedance, ρ ₀be gas density, t is the thickness of perforated plate, and σ is the punching rate of perforated plate, and w is angular frequency, and m is relative acoustic mass, c ₀be the spread speed of sound wave in gas, r is relative acoustic resistance, and η is kinematic coefficient of viscosity, k _racoustic resistance constant, k _mit is acoustic mass constant.

The specific acoustic impedance of the cavity 5 after perforated plate 3 can be tried to achieve by the specific acoustic impedance computing formula of rectangular cavity, the bottom of supposing cavity 5 is rigid walls, unit area impedance is infinitely great, the relative sound impedance of cavity porch is: z=-jcot (wD/c), in formula, z is relative sound impedance, and D is the longitudinal degree of depth of cavity, and c is the velocity of sound.

The acoustic absorptivity of perforation sound absorber can be expressed as:

α_{n} = \frac{4 r}{{(1 + r)}^{2} + {(wm - \cot (wD / c_{0}))}^{2}}

Hence one can see that: by thickness t, aperture d, punching rate σ, the longitudinal depth D of cavity of appropriate design perforated plate, can, under certain gas operating mode, try to achieve r, m, and then calculate the absorption coefficient curve of this perforation sound absorber.

Because perforation sound absorber of the present invention has symmetry, thereby the design parameter of one side only need be discussed.In order to absorb low-frequency noise, punching rate that need to be less, larger thickness of slab and the longitudinal degree of depth of cavity 5, flow but thickness of slab and the longitudinal degree of depth of cavity 5 affect respectively weight and the inner flue gas of the stove of perforation sound absorber, thereby need strict control and as far as possible little.In order to increase the effectively longitudinally degree of depth of perforation, perforation place that is chosen in perforated plate increases the internal lining pipe that 1mm is thick, 7～8mm is long, is equivalent to increase the thickness of slab of perforated plate, and actual plate face just mainly works to support internal lining pipe, therefore 2mm is thick, not only ensure equivalent plate thickness but also controlled plate body quality.Perforation sound absorber (one side) design parameter of the present invention and third-octave centre frequency acoustic absorptivity be respectively in table 1 and table 2, the acoustically effective of the perforation sound absorbers of different pipe layers as shown in Figure 8:

The table 1 different pipe layer perforation perforated plate of sound absorber and the design parameter of cavity and internal lining pipe

The acoustic absorptivity of the different pipe layer of table 2 perforation sound absorber

As shown in Figure 8: the perforation sound absorber of different pipe layers has at the centre frequency place of 80Hz the acoustic absorptivity that exceedes 0.9, and 1/2 maximum acoustic absorptivity all reaches two third-octaves, meets the designing requirement of low frequency absorption.Can see, larger cavity D can obtain wider low frequency absorption frequency band, but need to sacrifice design space simultaneously.

The setting of perforation sound absorber 2:

Known according to the crest frequency of actual measurement noise: in stove, crest frequency correspondence (3,1,0), (4,1,0) and (5,0,0) three kinds of normal modes.By three kinds of normal modes decompose can with X-axis (length direction) and Y-axis (width) in a certain angle, along Z axis (short transverse) propagate sound wave.In order to add perforation not affect the proper flow of flue gas after sound absorber, the sound absorber 2 of boring a hole is preferably parallel to flow of flue gas direction (Z axis); In order to absorb the sound wave of X-axis (length direction) and Y-axis (width) and to ensure maximum sound absorption area simultaneously, perforation sound absorber 2 is preferably disposed on the diagonal of furnace chamber.To sum up, the plan of establishment of perforation sound absorber 2 of the present invention is: on the diagonal of each section of furnace chamber cavity, insert the perforation sound absorber 2 of a slice perpendicular to horizontal plane, as shown in Figure 9, Figure 10.

Experimental example 2: from test result: the acoustic radiation of chimney has the greatest impact for sensitive spot outside factory, therefore consider to fix a silencer in the junction of chimney and furnace chamber, reduces boiler body and imports into the noise of chimney.

Be used for the design of the resonator muffler of waste heat boiler:

Utilize the principle of Helmholtz resonator, make in pipeline sound wave near resonant frequency because impedance mismatch, and most of acoustic energy is reflected back to Sounnd source direction, remaining fraction acoustic energy continues to propagate.Design object is mainly resonant frequency and sound deadening capacity, and design parameter comprises the aperture d of perforated plate 3, thickness t ₀, punching rate σ, the longitudinal depth D of cavity, the actual internal area S of resonator muffler etc.

Resonant frequency can be expressed as:

f_{0} = \frac{c}{2 π} \sqrt{\frac{σ}{tD}}

t＝t ₀+0.8d

In formula, f ₀for resonant frequency, c is the velocity of sound, the punching rate that σ is perforated plate, the aperture that d is perforated plate, t ₀for the thickness of perforated plate, t is effective thickness, and D is the longitudinal degree of depth of cavity; For effective thickness t, because near air pore-throat portion air column two ends is also participated in vibration, thereby the present invention revises the thickness of perforated plate.

The computing formula of sound deadening capacity is:

= 101 g [1 + \frac{k^{2}}{{(\frac{f}{f_{0}} - \frac{f_{0}}{f})}^{2}}]

\begin{matrix} k = \frac{\sqrt{GV}}{2 S} & G = \frac{n S_{i}}{t} \end{matrix}

In formula, IL is sound deadening capacity, and G is conductivity, and n is little hole count, S _ifor the area of single aperture, the channel cross-sectional area that S is resonator muffler, the volume f that V is cavity is the sound wave frequency of importing perforated plate into, f ₀for the resonant frequency of resonator muffler.

Known according to above-mentioned design formula: to process low-frequency noise (the third-octave band of 80Hz centre frequency), it is resonant frequency 80Hz left and right, need less punching rate, larger perforated plate thickness and the longitudinal degree of depth of cavity, thereby perforation place that is chosen in perforated plate increases the internal lining pipe that 1mm is thick, 7mm is long, be equivalent to increase the thickness of slab of perforated plate, and the plate face of practical puncture plate just mainly works to support internal lining pipe thereby 2mm.In view of the narrower bandwidth of resonator muffler, can use for reference the method for series connection multi-cavity type resonator muffler, perforated plate is designed to slightly different structural parameters (the present invention adopts polylith perforation sound absorbers 2 different structural parameters is superposeed and forms the method for double-sided perforated acoustic board) along the direction of flow of flue gas, and then the resonant frequency of the each several part that suitably staggers, after overlapped in series, can widen noise elimination frequency band, as shown in Figure 2.

Polylith double-sided perforated acoustic board is suspended on constant spacing in the cone space of furnace chamber and chimney junction, perpendicular to horizontal plane, and is parallel to short exterior wall, wall is also installed perforation sound absorber simultaneously, flue gas flows through between double-sided perforated acoustic board, forms resonator muffler, as shown in Figure 1.

Directly affected the size of sound deadening capacity from sound deadening capacity formula: k, in order to obtain larger sound deadening capacity, need to increase conductivity G, cavity volume V or reduce the channel cross-sectional area S of silencer, by the known V=2*l*h*D of layout drawing, S=l*a, the length (equaling the width of furnace chamber) that wherein l is perforated plate, the height that h is perforated plate, a is the spacing between adjacent two double-sided perforated acoustic boards, brings into abbreviation can obtain:

\frac{h}{a} \sqrt{\frac{σD}{t}}

The visible parameter at perforated plate is definite, increase plate hight h, reduce distance between plates a and can increase k value, and then increase sound deadening capacity, but plate hight h is subject to the restriction of cone space, distance between plates a can not too smallly arrive affects flow of flue gas.The results showed, when combination parameter perforated plate resonator muffler adopts the structural parameters described in table 3, can, in the situation that not affecting flow of flue gas, make sound deadening capacity maximum.

The structural parameters of table 3 combination parameter perforated plate resonator muffler

Adopt the double-sided perforated acoustic board of the combination parameter of table 3 to contrast as shown in Figure 6 with the sound deadening capacity of the double-sided perforated acoustic board that adopts single parameter.

As shown in Figure 6: adopt the resonator muffler being formed by the double-sided perforated acoustic board of combination parameter on the third-octave frequency band of 80Hz centre frequency, to obtain sound deadening capacity more than 10dB, 2 times are widened than the frequency band that adopts the resonator muffler being formed by the double-sided perforated acoustic board of single parameter, can better eliminate low-frequency noise, its sound deadening capacity octave spectrum is as shown in table 4:

The sound deadening capacity of the resonator muffler that table 4 is made up of the double-sided perforated acoustic board of combination parameter

Centre frequency (Hz)	31.5	63	125	250	500100	0
							Heavy (dB) eliminates the noise	0.3	14.0	0.4	0.0	0.0	0.0

Install after resonator muffler of the present invention and (adopt the structural parameters of table 3), factory's circle ambient noise reaches the requirement of discharge standard substantially, and the Contrast on effect that resonator muffler front and back are installed is as shown in table 5:

Table 5 is installed resonator muffler front and back chimney noise and ambient noise/dB (A)

Embodiment 3: the identification of noise source

Owing to there is stream, heat, sound three's coupling in stove, pipe battle array itself is by form its geometric properties complexity with the extended surface tube of helical fin, and the resource that complete Modeling Calculation needs is too large, therefore analytical model has been done to following simplification and hypothesis:

1. according to flue gas composition relation, use the equation of gas state to calculate flue gas physical characteristic, find that its indices and air differ to be no more than 5%, in calculating, adopt air replacement flue gas;

2. because heat transfer process itself does not produce noise, be remote-effects flue gas physical characteristic, therefore do not consider the heat exchange situation of same furnace wall, tube wall in flow of flue gas process, the flue gas thermodynamic parameter of pipe interlayer all adopts segmentation temperature-averaging;

3. while managing the overall modeling of battle array, temporarily do not consider the impact of the helical fin of extended surface tube, whether checking naked pipe two dimensional model has uniformity with threedimensional model, if consistent, multirow row three-dimensional tube battle array can be reduced into local two-dimentional Guan Zhen, not only holding tube battle array feature but also save computational resource;

4. the single tube threedimensional model of setting up extended surface tube and naked pipe carries out simulation comparison, in order to revise the characteristic frequency of pipe battle array entirety;

5. get more representational two pipe layer high-pressure superheaters (bottom) and the pipe battle array calculating segmentation feature frequency except oxygen evaporator (top layer) in stove, estimate characteristic frequency region overall in stove with this.

One, naked pipe two dimensional model and threedimensional model consistency checking

1, the foundation of naked pipe two dimensional model and threedimensional model

In 2D model, caliber d=40mm, entrance length L ₁=200mm (5d), outlet length L ₂=600mm (15d), apart from limit wall distance L ₃=200mm (5d), totally 15000 unit, boundary layer cell size is 1mm.

In 3D model, caliber d=40mm, pipe range L=100mm, entrance length L ₁=200mm (5d), outlet length L ₂=600mm (15d), apart from limit wall distance L ₂=200mm (5d), totally 300000 unit, boundary layer cell size is 1mm.

2, naked pipe two dimensional model and threedimensional model simulation calculation

Gas Parameters adopts the operating mode of high pressure superheater organ pipe layer, in table 6.

Table 6 high pressure superheater organ pipe layer operating mode

	Temperature T	Smoke density	Smoke power viscosity	The velocity of sound	Flue gas flow rate
						Data	517℃	0.4567Kg/m3	3.72E-05	554.6m/s	16m/s

Note: the 1. thermodynamic parameter of flue gas all adopts the air status parameter under gateway mean temperature and average pressure;

2. flue gas flow rate adopts mass flow and local density to convert, and is a pipe layer entrance flow velocity, herein owing to being that single tube has also carried out dutycycle conversion.

Flow Field Calculation adopts LES(large eddy simulation), the time step that transient state is calculated is 0.0005s, calculating step is 2500 steps.In the flow field vorticity cloud atlas of two dimensional model and threedimensional model, all there is obvious vortex shedding phenomenon, further calculate the noise sound that single tube sends.

Except the main peak of 93.4Hz and 92.2Hz, also there is secondary peak at its high order harmonics place in the sound pressure level line spectrum of two dimensional model and threedimensional model, the high order harmonics of two dimensional model is more obvious.High order harmonics is mainly to be caused by the asymmetry in vortex shedding process, and asymmetric coming off can cause pipe pulsation resistance to produce high frequency item, and fluent can be modeled as dipole source by high frequency item, thereby occurs peak value in frequency spectrum.Two Dimensional Large Eddy simulation (LES-2D) module of fluent software in the time calculating because the incomplete symmetry (ubiquity) of grid there will be the asymmetric error of obvious vortex shedding, therefore the humorous frequency component of its high order is more obvious, threedimensional model asymmetric situation of vortex shedding in the time calculating with large eddy simulation is very weak, more meets physical conditions.Although two dimensional model exists the interference of higher harmonic components, secondly peak energy is much smaller than main peak (differing 16.6dB), and impact can be ignored.The characteristic frequency that two dimensional model and threedimensional model calculate differs 1.2Hz, and visible two dimensional model and threedimensional model can be of equal value for calculated characteristics frequency, therefore can adopt two dimension pipe battle array to replace three-dimensional tube battle array.

Two, pipe battle array noise characteristic frequency computation part is analyzed

Get more representational two pipe layers in stove, be high-pressure superheater (bottom, temperature is the highest, flow velocity is the fastest) and calculate segmentation feature frequency except the pipe battle array of oxygen evaporator (top layer, temperature is minimum, flow velocity is the slowest), estimate the characteristic frequency region of entirety in stove with this.

1, high pressure superheater organ pipe layer characteristic frequency computational analysis

Computation model is got the part pipe battle array 12*10 of the original Guan Zhen of 12*64 as analytic target.Limit wall condition adopts periodic boundary condition, ensures the continuous of left and right, flow field wall speed and vorticity, and less with actual conditions error, model has symmetrical property, mainly considers that the 1st row are to the middle the 11st pipe battle array flow field being listed as from right to left when computational analysis.Fluid domain is 850*8000, and pipe battle array FEM model is as follows, totally 375234 unit.

Table 7 high pressure superheater organ pipe layer operating mode

Temperature T

Smoke density

Smoke power viscosity

The velocity of sound

Flue gas flow rate

Data

517℃

0.4567Kg/m3

3.72E-05

554.6m/s

8.2m/s

2. flue gas flow rate adopts mass flow and local density to convert, and is pipe layer entrance flow velocity.

Flow Field Calculation adopts LES(large eddy simulation), the time step that transient state is calculated is 0.0005s, calculating step is 2500 steps.Vorticity cloud atlas by flow field can be seen, there is regular trailing vortex in front two array of pipes of Guan Zhen, and arrange the beginning from the 3rd, pipe starts to be subject to the impact of pipe all around, constantly there is the situation that front end vortex shedding adheres to, comes off, turbulence intensity is obviously greater than front two rows, and this point is seen more intuitively clearly by the video of recording.

Sound field is calculated and is adopted FWH method, and because the time step of Flow Field Calculation is 0.0005s, therefore Analysis of The Acoustic Fields frequency is 1000Hz, resolution ratio is 1Hz.According to the distribution in flow field, select representational horizontally-arranged pipe to carry out acoustic characteristic analysis as sound source, draw the sound pressure level line spectrum of each horizontally-arranged pipe sounding.Wherein, though pipe battle array the 1st, the 2nd row's sound pressure level has obviously unimodal, but amplitude than rear 10 array of pipes poor 10dB, can ignore overall contribution degree, then 10 rows' sound pressure level is except there being obvious peak value, also near characteristic frequency, there is certain secondary peak (84.9Hz～85.9Hz, maximum differs 3dB), and along with Guan Zhen extends along carrying out flow path direction, its turbulence intensity of pipe battle array after more leaning on has the trend (vorticity cloud atlas also can be found out) of increase, the integral energy of noise also increases, but the main peak amplitude of different pipe layers differs less than 3dB.Therefore after can concluding, any row of 10 comb battle arrays is suitable for overall noise contribution, and exists characteristic frequency at 95.9Hz～97.9Hz.

2, deoxygenation evaporator tube layer characteristic frequency computational analysis

Computation model is got the part pipe battle array 10*10 of the original Guan Zhen of 10*60 as analytic target.Limit wall condition adopts periodic boundary condition, and model has symmetrical property, mainly considers that the 1st row are to the pipe battle array flow field of middle the 11st row from right to left when computational analysis.

Table 8 deoxygenation evaporator tube layer operating mode

	Temperature T	Smoke density	Smoke power viscosity	The velocity of sound	Flue gas flow rate
						Data	128℃	0.8941Kg/m3	2.32E-05	401.1m/s	4.1m/s

Sound field is calculated and is adopted FWH method, and because the time step of Flow Field Calculation is 0.0005s, therefore Analysis of The Acoustic Fields frequency is 1000Hz, resolution ratio is 1Hz.According to the distribution in flow field, select representational horizontally-arranged pipe to carry out acoustic characteristic analysis as sound source, obtain the sound pressure level line spectrum of horizontally-arranged pipe sounding.

It is obvious that the spectrum peak of deoxygenation evaporator tube battle array is not so good as high-pressure superheater, main cause should be that the decline of flow velocity causes reducing of rapid intensity, although pipe battle array also exists vortex shedding, regularity has differed from a lot, but still has the such characteristic spectra of 34.2Hz～42.7Hz.

In addition, contrast high pressure superheater organ pipe battle array and the vorticity cloud atlas of deoxygenation evaporator tube battle array and the noise sound of corresponding horizontally-arranged pipe, the turbulence intensity of high pressure superheater organ pipe layer is much larger than deoxygenation evaporator tube layer, noise energy exceeds nearly 10 times (sound pressure level differs 10dB), this is mainly to be caused by the difference of flue gas flow rate, the size of visible pipe interlayer noise is to become positively related with flow velocity, therefore can infer for the noise high pressure superheater organ pipe layer in whole stove to have decisive role.

Three, extended surface tube and the contrast of naked pipe simulation result and characteristic frequency correction

1, the foundation of extended surface tube FEM model

The physical dimension of extended surface tube and FEM model, caliber 40mm, pipe range 100mm, pitch of fin 8mm, fin width 1mm, fin height 15mm, fluid domain is still 400mm × 800mm with being consistent before, computational fields is totally 1654546 unit.

2, extended surface tube and the contrast of naked pipe simulation result

Distinguish simulation calculation high-pressure superheater and remove extended surface tube single tube flow field and the sound field under two operating modes of oxygen evaporator, and contrasting with naked pipe.

Equally there is vortex shedding from the visible extended surface tube of vorticity cloud atlas with naked pipe, further calculating noise sound pressure level can be found, high-pressure superheater and be respectively 67.1Hz and 33.7Hz except the crest frequency of extended surface tube under two kinds of operating modes of oxygen evaporator, crest frequency 92.2Hz and 46.6Hz than naked pipe have all declined 27.3%, peak sound pressure level decline respectively 5.2dB and 1.3dB, the slower helical fin impact of flow velocity is less; Two kinds of operating mode extended surface tubes coincide with the low frequency part trend below naked pipe 300Hz, because the asymmetric frequency spectrum of vortex shedding all exists higher harmonic components; Extended surface tube peak sound pressure under two kinds of operating modes differs 14.4dB, and naked pipe peak sound pressure differs 18.3dB, also reflects that high pressure superheater organ pipe layer plays a decisive role for noise in whole stove.

3, high-pressure superheater and the correction of deoxygenation evaporator tube layer characteristic frequency

By the characteristic frequency of contrast extended surface tube and naked pipe, adopt the correction means of percentage side-play amount to revise the characteristic frequency of Guan Zhen, result is as follows:

The correction of table 9 characteristic frequency

Four, acoustic resonance computational analysis in stove

Because whole furnace chamber can be regarded a 18.5m*5.5m*35m as, length and width direction is the cuboid operatic tunes that border, short transverse are the direction of propagation, therefore likely form standing wave.Temperature inequality in stove causes smoke density, the velocity of sound not to be uniformly distributed, and in the time calculating normal frequency, still adopts segmentation to do the method for temperature-averaging, obtains the list of each interval velocity of sound:

Each layer of velocity of sound of table 10 waste-heat oven

Normal frequency in furnace chamber distributes main length and width direction, the 100Hz of investigating with interior all-bottom sound.

In table 11 waste heat boiler chamber, each layer of normal frequency distributes

According to the distribution of the distribution of each layer of normal frequency and each layer of characteristic frequency, known high pressure superheater organ pipe layer characteristic frequency may excite (3,1,0) and (5,0,0) two kinds of normal frequencies, deoxygenation evaporator tube layer characteristic frequency may excite (3,0,0) normal frequency, in furnace chamber, form standing wave, the noise of Enhanced feature frequency.

Five, boiler noise propagation law computational analysis

In combustion turbine exhaustion mouth and horizontal flue, also exist low frequency to have tune component, for noise in further discrimination stove produces reason, can carry out sound transmission loss and oise insulation factor calculating to boiler, in conjunction with measured data, noise is mainly to be imported into or because of the new flow noise producing of flow of flue gas and the contribution amount of two kinds of noises by combustion chamber in comparative analysis stove.

1, furnace chamber sound transmission loss is calculated

The furnace chamber of whole waste heat boiler can be regarded as a rectangle operatic tunes, because heat exchanger tube layer has been placed in inside, sound wave propagation meeting in stove is produced to certain impact.By setting up the operatic tunes model of local Guan Zhen, the acoustic pressure of simulation calculation outlet and entrance in Virtual lab, and then obtain the sound transmission loss of the operatic tunes.

Taking high-pressure superheater section as example, the operatic tunes FEM model of building up is imported to Virtual lab, corresponding gas medium parameter (Gas Parameters under high-pressure superheater operating mode) is set, entrance boundary condition is made as plane wave, and export boundary condition is made as ature of coal impedance, resolution ratio 10Hz, do the frequency sweep of 20Hz～2000Hz frequency range, according to the entrance acoustic pressure calculating and outlet acoustic pressure, calculate with sound transmission loss definition, obtain the sound transmission loss curve of the operatic tunes.

Remove in a like fashion the sound transmission loss simulation calculation of oxygen evaporator interval furnace chamber.

Can be found out by above result of calculation, the furnace chamber that contains heat exchanger tube layer is very little for the iris action of the low-frequency noise below 800Hz, and the sound transmission loss of individual layer is all less than 0.5dB.The sound transmission loss of each pipe layer is directly superposeed, can roughly estimate the sound transmission loss (non-exact value) of whole furnace chamber.

Table 12 furnace chamber sound transmission loss

Centre frequency	31.5	63	125	250	500	1000
							TL（dB）	13.8	16.9	20.1	23.2	26.1	28.9

2, boiler component oise insulation factor is calculated

Measuring the data obtained is all furnace wall outside, considers that the different parts of boiler have different housings and insulation layer thickness, brings thus the difference of oise insulation factor may affect the judgement of true noise in stove, calculates therefore need carry out the oise insulation factor of boiler component.

The each parts sound insulating material of table 13 boiler

	Horizontal flue	Furnace wall hypomere	Furnace wall stage casing	Furnace wall epimere	Chimney
						Lining steel plate thickness (mm)	2	2	2	2	2
Inside thermal conservation material thickness (mm)	100	140	100	80	60
						Hull plate thickness (mm)	8	8	8	8	4
External thermal insulation thickness (mm)	_-	_-	_-	_-	80

Note: insulation material is alumina silicate felt, density is 100～120kg/m ³, wherein 60mm, 80mm, the thick 35mm*2 of being respectively of 100mm, 140mm, 35mm*3,55mm*2,55mm*3 compression form, and steel plate density is 7850kg/m ³.

Because the thickness of steel plate is enough thin with respect to wavelength, can think that steel plate does mass motion as piston, be simple two wall sound insulation problem by problem reduction, according to four equations of two groups of Boundary Condition for Solvings, the oise insulation factor that obtains two walls is:

TL = 20 \lg | \frac{1}{2} (1 + \frac{R_{1}}{R_{3}} + \frac{jω (M_{1} + M_{2})}{R_{3}}) \cos K_{2} D + j \frac{1}{2} (2 + \frac{jω (M_{1} + M_{2})}{R_{3}} - \frac{ω^{2} M_{1} M_{2}}{R_{3}^{2}}) \sin K_{2} D |

In formula, R ₁, R ₂, R ₃be respectively boiler internal flue gas acoustic impedance, insulation material acoustic impedance, boiler extraneous air acoustic impedance, unit is N*s/m ³; M ₁, M ₂be respectively the surface density of lining steel plate and hull plate, unit is kg/m ²; K ₂for the wave number of insulation material, unit is 1/m, and D is insulation layer thickness, and unit is m.

For medium and low frequency situation, K ₂d<<1, cosK ₂d=1, sin K ₂d=0, oise insulation factor can be reduced to:

= 20 \lg | \frac{1}{2} (1 + \frac{R_{1}}{R_{3}} + \frac{jω (M_{1} + M_{2})}{R_{3}}) |

Stove outer air specific acoustic impedance is got air constant at 20 DEG C, R ₃=415N* _s/ m ³;

As the frequency f >20Hz of sound, therefore medium and low frequency section oise insulation factor computing formula can further be reduced to:

TL = 10 \lg (\frac{ω^{2} {(M_{1} + M_{2})}^{2}}{{4 R}_{3}^{2}}) = 20 lgω + 20 \lg (M_{1} + M_{2}) - 10 \lg {4 R}_{3}^{2}

Meet quality control law, observe known this calculating formula and be equivalent to directly double-layer plate be stacked.The oise insulation factor (heat-insulation layer is equivalent to single wall, meets quality control) of adding on this basis heat-insulation layer, total oise insulation factor is:

TL＝20lgω+20lg(M ₁+M ₂+M ₃)-10lg4R ₃ ²

In formula, M ₃for the surface density of heat-insulation layer, unit is kg/m ².

From result of calculation, for medium and low frequency section, the each parts of boiler are owing to being in quality control district, and the difference of parts oise insulation factor is not affected by noise frequency, is a fixed value.

Six, noise main sound source discrimination in stove

1, combustion machine exhaust noise

Suppose combustion machine exhaust noise harmless propagation in horizontal flue, can obtain the A sound level of combustion machine exhaust noise in horizontal flue according to its Noisy acoustic power; Consider that combustion machine exhaust noise nondestructively imports boiler body into by horizontal flue, can obtain the A sound level of combustion machine exhaust noise in boiler body according to its Noisy acoustic power; Consider that combustion machine exhaust noise is entering chimney after whole boiler body, have sound transmission loss (the furnace chamber inner tube layer series connection sound transmission loss of calculating) above, exhaust noise acoustical power deduction sound transmission loss can be obtained to the A sound level of combustion machine exhaust noise in chimney:

Table 14 fires the A sound level of machine exhaust noise in the each parts of boiler

Note: in form, "-" is that when calculating or test due to theory, Frequency Band Selection causes obtaining accurate data

2, boiler internal noise

Provided by combustion machine exhaust noise because the noise in horizontal flue is approximate, therefore by relatively firing machine exhaust noise side test A sound level outside A sound level and horizontal flue in horizontal flue, can obtain the actual oise insulation factor of horizontal flue:

Outside A sound level and oise insulation factor in the flat flue of table 15

Visible actual oise insulation factor is less than normal with respect to calculated value, and owing to having the connector (overhead speaker) between heat-insulation layer and leaking voice phenomenon, this is normal result.The heat-insulation layer parameter of looking into the each parts of boiler is known, quite (steel plate thickness is identical with horizontal flue for the heat-insulation layer parameter of boiler body, alumina silicate felt thickness is slightly different), and oise insulation factor calculated value is very approaching, therefore can be similar to the actual oise insulation factor that replaces boiler body by the actual oise insulation factor of horizontal flue.The A sound level of each boiler body of actual measurement interval outside is added to the actual oise insulation factor of boiler body can reverse goes out the noise grade A of the inner corresponding interval of boiler body; Because heat-insulation layer parameter and the horizontal flue at chimney place there are differences (the little 4mm of steel plate thickness), therefore the actual oise insulation factor of chimney is certainly little than horizontal flue, revise according to both differences of oise insulation factor theoretical value according to requirement of engineering, actual oise insulation factor by horizontal flue deducts 2.5dB at each octave Duan Jun, and chimney outer wall actual measurement noise grade A adds that this oise insulation factor can estimate the noise grade A of chimney inside:

The inner A sound level of the each interval of table 16 boiler body and chimney

3, boiler noise and the comparative analysis of combustion machine exhaust noise

The each interval noise grade A of contrast boiler body and combustion machine exhaust noise are in the A of boiler body inside sound level, can find that on the octave band of 63Hz boiler noise imports the noise (11dB) of boiler body into apparently higher than combustion machine exhaust noise, and both are substantially identical on other frequency bands, in deducibility stove, certainly there is thus regenerated noise to produce, and the peak value frequency range of the newly-increased noise octave band that is 63Hz.

According to the extended surface tube noise spectrum of simulation calculation above, can estimate the flow noise octave spectrum of pipe layer (because noise magnitude calcaneus rete lattice density, medium parameter etc. that CFD calculates are correlated with, therefore can only serve as relative magnitude), itself and boiler body regenerated noise (boiler noise and the difference of firing machine exhaust noise) are contrasted.

Table 17 furnace body regenerated noise A sound level and flow noise A sound level

Frequency	Boiler body regenerated noise A sound level (dBA)	The flow noise A sound level (dBA) that pipe battle array produces
			31.5	68.3	23.1
63	107.3	60.0
			125	101.5	46.3
250	107.3	43.5
			500	120.4	47.3
1000	118.2	46.9

Can find, boiler body regenerated noise is very identical in frequency spectrum trend with the flow noise that pipe battle array produces, and all has the peak value octave section of 63Hz, can conclude that thus the regenerated noise in stove is the flow noise of pipe battle array vortex shedding really.According to result of calculation, further in analytical furnace, in noise, exhaust is imported noise into managing the contribution amount of battle array vortex shedding flow noise at different frequency range:

Table 18 fires machine exhaust noise and the flow noise contribution amount for noise in stove

Octave center frequency	31.5	63	125	250	500	1000
							Import Noise contribution into	91.2%	6.5%	81.3%	85.1%	39.9%	58.9%
Pipe battle array flow noise contribution amount	8.8%	93.5%	18.7%	14.9%	60.1%	41.1%

Noise grade A in contrast chimney and combustion machine exhaust noise import the A sound level of chimney into: because the oise insulation factor of chimney wall is correction value, the sound transmission loss of furnace chamber is also engineering approximation value, so can there is error in the magnitude of noise, but relatively the trend of frequency spectrum can be found, chimney internal noise imports noise into respect to exhaust and have obvious peak value in the octave section of 63Hz, be the existence of provable regenerated noise according to conclusion before, and this noise should be also the flow noise (pipe battle array vortex shedding) that comes from boiler internal.

The noise grade A of contrast throat and combustion machine exhaust noise import the A sound level of chimney into: the noise of throat still exists obvious peak value than combustion machine exhaust noise in the octave section of 63Hz, but because the calculating of sound transmission loss is that rough (engineering approximation has been calculated a pipe battle array sound transmission loss, ignore each parts junction sound transmission loss of horizontal flue-boiler body-chimney, cause the sound transmission loss amount of calculation less than normal), so be inaccurate in magnitude but this does not affect the judgement to there being quadratic noise to produce in stove.

4, furnace wall noise testing result sound pressure level line spectrum is analyzed

Manage the sound pressure level line spectrum of layer downstream near furnace wall 1m place by high pressure superheater organ pipe layer downstream, high pressure evaporator (2) pipe layer downstream, high-pressure economizer (2) pipe layer downstream, high-pressure economizer (3), the obvious crest frequency of visible existence, be 74Hz～78.5Hz near waste-heat oven bottom, be 68Hz～74Hz near waste-heat oven top, this meets is previously the expectation of noise dominant frequency in stove to high-pressure superheater characteristic frequency, also meets along with highly increase, flow velocity slow down characteristic frequency by downward trend; There is secondary peak in the frequency multiplication place in characteristic frequency, this is closely similar with the noise spectrum producing because of vortex shedding in computation model.

The error of simulation result is mainly derived from approximate, the partial simplified of model and the precision of computing grid of flue gas thermodynamics information.The above two are discussed above, the obtaining and then affect noise information of the precision major effect boundary layer flow information of grid, one times of mesh refinement doubles computing time, but for its error of calculated characteristics frequency only 5%～10%, this calculating considers that two dimensional model grid is controlled at (8 core server 24h computing time) in Unit 500,000 by computational efficiency, and three-dimensional model gridding is controlled at (8 core server 72h computing time) in Unit 2,000,000.

Warp and experimental data comparative analysis, can determine in waste heat boiler that noise source is in the flow noise of combustion machine exhaust noise and pipe gust vortex shedding.At the concentrated 63Hz octave band of noise energy, flow noise is main sound source (contribution amount reaches 93.5%), therefore noise reduction measure should be around the flow noise that solves this frequency band.As need solve high-frequency noises (more than 200Hz), in considering flow noise, also need to reduce to fire machine exhaust noise.

By Modeling Calculation high-pressure superheater with except flow field and the sound field of two representative pipe layers of oxygen evaporator, and carry out characteristic frequency correction by the characteristic of extended surface tube, obtain drawing a conclusion:

1. the mechanism of production of flow noise in stove.In stove, the generation of noise is that smoke gas flow is crossed close arranging pipe battle array, and at the surperficial vortex shedding that forms rule of extended surface tube, and then lift and the resistance of generation pulsation, be that dipole source produces noise by FW-H equation by the lift of pulsation and resistance simulation, the vorticity cloud atlas of simulation calculation and sound pressure level line spectrum all reflect obvious vortex shedding phenomenon and characteristic frequency.Due to the asymmetry of vortex shedding, can produce the pulsation harmonic wave of high order, on frequency spectrum, be shown as the secondary peak at higher hamonic wave place, this point simulation and experiment result all embodies to some extent, has further verified that vortex shedding causes noise in stove.

2. vortex shedding characteristic frequency and influence factor thereof.High-pressure superheater and be respectively 92.2Hz and 46.6Hz except the characteristic frequency of the single pipe under oxygen evaporator operating mode.High-pressure superheater and except the Guan Zhen under oxygen evaporator operating mode, because Guan Zhen arranges closely, the situation that ubiquity whirlpool adheres to, comes off, the Interaction enhanced in pipe way flow field, single characteristic frequency passivation is characteristic spectra, is respectively 95.9Hz～97.9Hz and 34.2Hz～42.7Hz.The characteristic frequency of the extended surface tube under two kinds of operating modes is respectively 67.1Hz and 33.7Hz, peak sound pressure level decline 5.2dB and 1.3dB, and the existence of fin has reduced characteristic frequency and noise energy, and flow velocity is faster, and the impact of fin is larger.Be respectively 69.7Hz～71.2Hz and 24.9Hz～31.0Hz by pipe layer characteristic spectra under two kinds of operating modes after extended surface tube characteristic revision.Contrast the peak sound pressure of single naked pipe, single extended surface tube and Guan Zhen, high-pressure superheater operating mode is than exceeding respectively 18.3dB, 14.4dB, 10dB except oxygen evaporator operating mode, therefore high pressure superheater organ pipe layer has decisive role for noise in stove.

3. the main sound source discrimination of noise in stove.Warp and experimental data comparative analysis, can determine in waste heat boiler that noise source is in the flow noise of combustion machine exhaust noise and pipe gust vortex shedding.At the concentrated 63Hz octave band of noise energy, flow noise is main sound source (contribution amount reaches 93.5%), and suitable in both contribution amount of medium-high frequency section.

Wherein, in the recognition methods of above-mentioned noise source, naked pipe 2D FEM model schematic diagram, naked pipe 3D FEM model schematic diagram, naked pipe two dimensional model noise sound curve map, naked pipe threedimensional model noise sound curve map, high pressure superheater organ pipe layer FEM model schematic diagram, high pressure superheater organ pipe layer FEM model spread parameter schematic diagram, deoxygenation evaporator tube layer row FEM model schematic diagram, deoxygenation evaporator tube layer row FEM model spread parameter schematic diagram, the physical dimension of extended surface tube and FEM model schematic diagram, the sound transmission loss curve map of the high-pressure superheater operatic tunes, except the sound transmission loss curve map of oxygen evaporator interval furnace chamber, each pipe interval furnace chamber series connection sound transmission loss curve map, furnace wall parts cross-sectional view, the theoretical oise insulation factor curve map of boiler component, the each interval noise grade A of boiler body and combustion machine exhaust noise are at the A of boiler body inside sound level correlation curve figure, boiler body regenerated noise A sound level and flow noise A sound level correlation curve figure, chimney internal noise A sound level is imported noise grade A correlation curve figure into the exhaust of combustion machine, throat noise grade A imports noise grade A correlation curve figure into the exhaust of combustion machine, the sound pressure level line spectrum figure in high pressure superheater organ pipe layer downstream, the sound pressure level line spectrum figure in high pressure evaporator (2) pipe layer downstream, the sound pressure level line spectrum figure in high-pressure economizer (2) pipe layer downstream, the application for a patent for invention " a kind of waste heat boiler internal noise source discrimination " of submitting on the same day with the present invention, near the sound pressure level line spectrum figure at furnace wall 1m place, is seen in high-pressure economizer (3) pipe layer downstream.

The operation principle of a kind of embodiment of the present invention:

1. perforation sound absorber is eliminated the principle of the flow noise of pipe battle array vortex shedding:

At the high-pressure superheater of waste heat boiler, low-pressure superheater, high pressure evaporator, low pressure evaporator, high-pressure economizer, low-pressure coal saver with in except the cavity in oxygen evaporator, waste heat boiler absorbent lined barrier is all set, this waste heat boiler absorbent lined barrier is made up of two perforated plates 3 by certain punching rate and liner plate 4 and forms two cavitys 5, this structure is in fact the one application of resonance perforation sound absorber, and its theoretical foundation is Helmholtz resonator principle.The similar piston of air column in internal lining pipe 8 on perforated plate 3, has certain acoustic mass, and cavity 5 is similar to air spring, has certain elasticity, and the two forms a resonator system.In the time that sound wave reaches aperture, under sound wave effect, air column just produces vibration, and frictional damping when vibration makes a part of acoustic energy be converted to thermal energy consumption to dissipate, and due to the unexpected variation of acoustic impedance, a part of acoustic energy will be reflected back sound source simultaneously.Finally reach the noise of absorption boiler inside, the object of the operatic tunes resonance of minimizing noise in propagation, the elimination boiler of boiler internal.

2. the principle that adopts resonator muffler to eliminate the flow noise of pipe battle array vortex shedding and amplify noise with the sympathetic response that the corresponding normal frequency sound wave that it excites in furnace chamber forms:

The resonator muffler that is provided for waste heat boiler in the furnace chamber of waste heat boiler and the junction of chimney, in the time that flue gas flows to chimney from furnace chamber, flue gas is divided into several regions by double-sided perforated acoustic board 1.According to the principle of Helmholtz resonator, by the polylith perforation sound absorber 2 of the Different structural parameters double-sided perforated acoustic board 1 forming that superposes, can make sound wave in furnace chamber near resonant frequency because impedance mismatch, thereby most of acoustic energy is reflected back to Sounnd source direction, all the other fraction energy continue to propagate, thereby reduce boiler body and imported into the noise of chimney, reached the object of noise reduction.

Claims

1. a control method for waste heat boiler internal noise, is characterized in that, adopts perforation sound absorber (2) to eliminate the flow noise of pipe battle array vortex shedding; Adopt resonator muffler to reduce furnace chamber noise and propagate to chimney, described furnace chamber noise mainly comprises the sympathetic response amplification noise that the pipe battle array flow noise of vortex shedding and the flow noise of this pipe battle array vortex shedding and its corresponding normal frequency sound wave exciting in furnace chamber form; The both sides that described perforation sound absorber (2) fits in respectively liner plate (4) by two perforated plates (3) form, and described resonator muffler is made up of double-sided perforated acoustic board (1) and the one side sound absorption structure (9) of being located at furnace chamber inside.

2. the control method of waste heat boiler internal noise according to claim 1, it is characterized in that, while adopting perforation sound absorber (2) to eliminate the flow noise of pipe battle array vortex shedding, this perforation sound absorber (2) is arranged in the cavity between exchanging pipe of boiler by waste layer.

3. the control method of waste heat boiler internal noise according to claim 2, it is characterized in that, while adopting perforation sound absorber (2) to eliminate the flow noise of pipe battle array vortex shedding, this perforation sound absorber (2) is arranged on the diagonal of the cavity between exchanging pipe of boiler by waste layer and vertical with horizontal plane.

4. the control method of waste heat boiler internal noise according to claim 1, it is characterized in that, while adopting resonator muffler minimizing furnace chamber noise to propagate to chimney, this resonator muffler is installed in the chimney of waste heat boiler and the cone space of furnace chamber junction.

5. the control method of waste heat boiler internal noise according to claim 4, it is characterized in that, while adopting resonator muffler minimizing furnace chamber noise to propagate to chimney, the double-sided perforated acoustic board (1) of this resonator muffler is arranged in the chimney of waste heat boiler and the cone space of furnace chamber junction, and one side sound absorption structure (9) is arranged on the inwall of cone space; In cone space, double-sided perforated acoustic board (1) is arranged side by side and perpendicular to horizontal plane along the direction of flow of flue gas with the spacing of fixing.

6. the control method of waste heat boiler internal noise according to claim 1, it is characterized in that, the sympathetic response that the flow noise of described pipe battle array vortex shedding and the flow noise of this pipe battle array vortex shedding and its corresponding normal frequency sound wave exciting in furnace chamber form is amplified noise and is identified by the following method acquisition:

7. the control device of realizing the waste heat boiler internal noise of method described in claim 1～6, is characterized in that, is made up of double-sided perforated acoustic board (1) and the one side sound absorption structure (9) of being located at furnace chamber inside; Described double-sided perforated acoustic board (1) is located at furnace chamber inside side by side, and is made up of perforation sound absorber (2) stack of polylith different resonant frequencies; Described perforation sound absorber (2) comprising: two perforated plates (3) and a liner plate (4), and two perforated plates (3) fit in respectively the both sides of liner plate (4); The both sides that liner plate (4) is close to perforated plate (3) are trench structure, make to form sound absorption cavity (5) between perforated plate (3) and liner plate (4), and perforation place on perforated plate (3) is provided with internal lining pipe (8); Described one side sound absorption structure (9) is located on the inwall on waste heat boiler top.

8. the control device of waste heat boiler internal noise according to claim 7, it is characterized in that, described one side sound absorption structure (9) comprising: a perforated plate (3) and a liner plate (4), perforated plate (3) fits in a side of liner plate (4), liner plate (4) one sides of being close to perforated plate (3) are trench structure, make formation sound absorption cavity (5) between perforated plate (3) and liner plate (4).

9. according to the control device of the waste heat boiler internal noise described in claim 7 or 8, it is characterized in that, the thickness of described perforated plate (3) is 2mm, and aperture is 10～13mm, and punching rate is 0.4%～0.55%; Longitudinal degree of depth of described cavity (5) is 200mm; The length of described internal lining pipe (8) is 7mm.

10. the control device of waste heat boiler internal noise according to claim 9, is characterized in that, the spacing between adjacent two double-sided perforated acoustic boards (1) is 0.5～2 meter; The height of double-sided perforated acoustic board (1) is 1.0～5 meters; Described double-sided perforated acoustic board (1) is made up of 3～8 different perforation sound absorber (2) stacks of resonant frequency.