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The muffler principle and structure of the muffler is a device that can pass airflow and effectively reduce noise. It is usually installed on the intake and exhaust pipes of various aerodynamic devices to reduce the radiation or along the intake and exhaust ports. The noise transmitted by the pipeline. The principle of muffling is mainly to convert the sound wave into heat energy through the sound absorbing structure of the muffler, or to cause reflection interference of the sound wave to reduce or eliminate the noise intensity discharged into the environment. The muffler has many structural forms, which are divided by acoustic principle and can be basically divided into three categories: resistant muffler, resistive muffler and impedance composite muffler.
(1) The structural feature of the resistant muffler resistant muffler is that no sound absorbing material is added inside the muffler, but the sound wave is reflected by the cross section of the muffler channel to reduce the noise intensity. The acoustic principle is similar to the Filter in the circuit, and it plays a role in the resistance of acoustics. Its structural form mainly consists of single or multiple expansion chambers, as shown in (a) and (b); or by using bypass branches to make parts The path of the acoustic wave is exactly equal to half a wavelength, and the phases are 180° out of phase, thereby generating interference and weakening the intensity of the noise, and its structure is as shown in (c).
Resistive muffler structure (2) Resistive muffler Resistive muffler mainly applies porous or fibrous sound absorbing material to the internal air passage of the muffler, and uses the friction and viscous resistance of the material to convert the acoustic energy into heat energy. Thereby the noise is attenuated. The resistive muffler has good sound absorption effect on medium and high frequency noise, and its common structural forms are: straight tube type, folding board type, chip type and sound flow type.
Factors Affecting the Performance of the Muffler In addition to its direct relationship with the structural form, the muffler performance of the muffler has a direct impact on its sound absorbing material, channel cross-sectional area, muffler length, and face structure. (1) The selection of sound absorbing materials for sound absorbing materials depends on the frequency characteristics of the noise source. Different materials have different sound absorption coefficients for different frequencies. Even for the same material, different thicknesses and different bulk density have different sound absorption coefficients. In addition, the temperature, humidity, dust content and other conditions of the medium must be considered. The material has a high bulk density and is unfavorable for high-frequency sound wave absorption; the bulk density is low, which is unfavorable for low-frequency absorption. The sound absorption coefficient generally increases with the thickness of the material, but the increase of the sound absorption coefficient after the thickness increases to a certain value is not obvious. Commonly used sound absorbing materials are ultra-fine glass wool, rock wool, fiberboard, foam and the like.
(2) Muffler channel cross-section size The size of the muffler cross-section size is directly related to the medium flow velocity, pressure drop and noise. The choice of the cross-sectional area of ​​the channel also involves the determination of the muffler channel structure. Generally, the effective channel cross-sectional area should not be less than the cross-sectional area of ​​the original inlet and exhaust ports. Otherwise, if the flow rate is too high, the secondary noise generated will increase. Increasing the effective channel cross-sectional area reduces the flow rate and correspondingly the resistance loss is also reduced.
The measures taken are based on the analysis of the above-mentioned causes of damage. We have strengthened the acceptance of the products of the manufacturers so that the products fully meet the requirements of the design drawings. During the installation process, the technicians of the manufacturer and the user unit are instructed on site until the correct installation is completed. After the overhaul in January 1998, the 3 main fans were turned on normally and the muffler operation was restored to normal. Of course, it should be pointed out that although the muffler has a certain noise reduction effect, it is still not enough to truly meet the noise requirements of the environment. The author suggests that because the impedance compound muffler is widely used, the noise cancellation effect is better than the simple resistance muffler. Therefore, the appropriate impedance composite muffler should be selected after detecting the noise property and noise intensity.
Feiyiya Inclined Plate Clarifiers Use Gravity & Innovative Engineering
A gravity clarifier is the most economical method of removing solids from liquids, using natural gravity as the source of energy and it is free. A clarifier simply provides a non-turbulent zone where heavier than liquid solids, suspended by turbulence, are given sufficient time to settle to a quiescent surface. The HEI inclined plate clarifiers are compact units with multiple layers of settling area utilizing less than 25% of the floor space required by conventional clarifiers.
Principle of Clarifiers
A particle carried forward by the velocity of the liquid flow must settle at a rate that allows it to reach the bottom before passing through the clarifer. Thus, particles beginning at a point [a" must traverse some route lying between ab and ab` in order to avoid being carried over the outlet.
If V is the horizontal velocity of the liquid, S the solids particle vertical settling velocity, L the length of the settling device, and D its depth, then particles entering at point A will settle to the bottom of the device only if V does not exceed: S(L/D)Since Vmax / S = L / D then, Vmax = S (L / D)
Therefore, the velocity at which a horizontal clarifying device may be operated successfully is directly proportional to its length and inversely proportional to its depth.
This analysis applies to multiple horizontal plate units also. The spacing between plates is usually a few inches as opposed to a depth of several feet in a horizontal tank; therefore, [settling-out" times are dramatically reduced. The flow must be non-turbulent to prevent settled solids from being re-entrained within the moving liquid. Small plate spacing and a large surface area permits laminar flow at higher velocities than large horizontal tanks would allow.
Horizontal clarifying devices become self-flushing if they are inclined at an angle which exceeds the angle of repose of the settled solids. In such cases, flow enters the lower end of the device where settling particles move to the floor eventually sliding back out the entrance. Clear effluent leaves the top of the device.
However, when the device is inclined, the furthest settling particles no longer fall through distance D but some longer distance D`. This new longer settling distance D` is related to D by the relation: D = D` cos Ø.
Theta [Ø" is the angle, the device is inclined to the horizontal plane. Thus settling distance is increased by the factor: 1/cos Ø In the case where Ø = 60º, 1/cos Ø = 2.
The maximum settling distance is twice the distance between the plates. It is apparent then that the lower the angle of inclination, the smaller the settling distance. However, the angle of inclination must exceed the angle of repose of the solids to be separated. The previous equation may be modified to express the cosine of an inclined plate clarifying system as:
Vmax = L / (D / cosØ) (s) = L·cosØ / D (s)
Inclined Plate Clarifiers
A reduction of the required floor space is acquired by diminishing the separation between the horizontal plates to a few inches and stacking the settling surfaces. Inclining the plates to provide self flushing, 45º for heavy particles and 60º for light particles, reduces the available horizontal projected area (effective settling area) by a factor equivalent to the cosine of the angle. The surface area diagram (below) graphically compares the floor space requirements of an HEI inclined plate clarifier with the equivalent horizontal projected settling area.
Settling Rate
The settling rate for a specific solids should be determined by standard laboratory tests. Light particles, such as metal hydroxides, usually require a design parameter of 0.25 – 0.50 gallons per minute per square foot of horizontal projected area. These low density solids require the inclined plates to be set at a 60º angle to induce the particles to slide down the plate. Heavier particles (such as sand that easily flow) will readily slide from plates set at a 45º angle.
Maximum flow rate of an inclined plate clarifier is based on the flow rate per unit of a horizontally projected surface area. Retention time in the clarifier is not a design criteria. However, attaining optimum performance requires the prudent design to recognize several additional, very important factors.
Inclined plate clarifier, Lanmei inclined plate clarifier, Inclined Tube Settler,High-Efficiency Inclined Tube
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