Exhaust silencer for microturbines

Methods, systems, and apparatuses for exhaust silencers for engines, such as microturbines, are described. An exhaust silencer reduces noise produced by an engine. While passing through an exhaust silencer, an exhaust stream from the engine makes one or more turns, thereby reducing turbine noise. An exhaust silencer includes a body, a cavity in the body, a baffle plate that partially divides the central cavity, an inlet port formed in a first surface of the body, and an outlet port formed in a second surface of the body. The inlet port is configured to receive an exhaust stream that flows through the cavity, around the baffle plate. The outlet port is configured to discharge the exhaust stream from the body.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to the reduction of noise generated by turbines.

2. Background Art

Gas powered engines, such as microturbines, are used in many applications, including power generation. For example, such engines may be used to generate electricity for buildings. However, during operation, such engines may generate noise. For example, during normal operation, a turbine of a microturbine can generate a moderate amount of noise. During shutdown, a turbine may emit a loud “screech” type sound. When installed in public (e.g., urban) locations, the generated noise may be undesirable. Regulations may even exist for limiting generated noise in some localities.

Thus, what is needed are ways of reducing noise generated by engines, such as microturbines.

BRIEF SUMMARY OF THE INVENTION

Methods, systems, and apparatuses for exhaust silencers for engines, such as turbines, are described. In aspects of the present invention, an exhaust silencer reduces noise produced by a turbine or other type of engine. An exhaust stream from the turbine is passed through the exhaust silencer, making one or more turns in the exhaust silencer, thereby reducing turbine noise.

In an aspect of the present invention, an exhaust silencer is provided. The exhaust silencer includes a body, a cavity in the body, a baffle plate that partially divides the central cavity, an inlet port formed in a first surface of the body, and an outlet port formed in a second surface of the body. The inlet port is configured to receive an exhaust stream that flows through the cavity, around the baffle plate. The outlet port is configured to discharge the exhaust stream from the body.

In an example aspect, the baffle plate is positioned in the cavity to create a u-shaped compartment in the body. The u-shaped compartment includes first and second longitudinal compartments that are connected by an opening at an end of the cavity.

In another example aspect, the inlet port is positioned such that the inlet port infuses the exhaust stream into a longitudinal segment of the u-shaped compartment in a direction that is perpendicular to a flow of the exhaust stream through the longitudinal segment. Alternatively, the inlet port may be otherwise positioned.

In another example aspect, the outlet port is positioned such that the outlet port discharges the exhaust stream from a longitudinal segment of the u-shaped compartment in a direction that is perpendicular to a flow of the exhaust stream through the longitudinal segment. In an alternative aspect, the outlet port discharges the exhaust stream from the longitudinal segment in the same direction as the direction of flow of the exhaust stream through the second longitudinal segment. The outlet port may be otherwise positioned in further alternative aspects.

In another example aspect, a sound absorbing and/or heat resistant material covers at least a portion of a surface of the cavity and/or the baffle plate.

In another aspect of the present invention, a microturbine system is described. The microturbine system includes a microturbine having an exhaust port and an exhaust silencer coupled to the exhaust port. The exhaust silencer reduces noise generated by the microturbine.

In another aspect of the present invention, a method for silencing a turbine is provided. An exhaust stream is received from a turbine at an inlet port of a body. The exhaust stream flows around a baffle plate in a cavity of the body. The exhaust stream is discharged from an outlet port of the body.

In an example aspect, the exhaust stream flows along a u-shaped path through the cavity formed by the baffle plate. In another example aspect, sound generated by the turbine is absorbed with a material that lines at least a portion of a surface of the cavity.

These and other objects, advantages and features will become readily apparent in view of the following detailed description of the invention. Note that the Summary and Abstract sections may set forth one or more, but not all exemplary embodiments of the present invention as contemplated by the inventor(s).

DETAILED DESCRIPTION OF THE INVENTION

Introduction

Example Embodiments

Methods, systems, and apparatuses for exhaust silencers for engines such as turbines are described. In embodiments, exhaust silencers reduce noise produced by gas powered engines, such as microturbines or other types of power generating equipment. An exhaust stream of an engine is passed through an exhaust silencer. When passing through the exhaust silencer, the exhaust stream makes one or more turns, which causes a reduction in noise.

The example embodiments described herein are provided for illustrative purposes, and are not limiting. While described herein with respect to microturbines, the examples described herein may be adapted to any type of engine. Further structural and operational embodiments, including modifications/alterations, will become apparent to persons skilled in the relevant art(s) from the teachings herein.

FIG. 1shows a conventional engine system100. As shown inFIG. 1, system100includes a turbine engine shown as a microturbine102. Microturbine102has an exhaust port104. During operation, a fuel (e.g., natural gas, propane, diesel or kerosene) is mixed with air and is ignited in microturbine102, resulting in the release of energy and in the release of exhaust gases that are discharged in an exhaust stream106from exhaust port104. The released energy may be used for a variety of purposes, including distributed power and combined power and heat applications. The discharge of exhaust stream106, however, results in unwanted noise. When installed in public (e.g., urban) locations, the generated noise may be undesirable.

FIG. 2shows an engine system200, according to an example embodiment of the present invention. System200is generally similar to system100shown inFIG. 100, with the addition of exhaust silencer202. As shown inFIG. 2, exhaust silencer202couples with exhaust port104and receives exhaust stream106. Exhaust silencer202reduces a noise content of exhaust stream106. Exhaust silencer202discharges an exhaust stream204, which contains less noise output for system200relative to system100.

In an embodiment, exhaust silencer202may have an internal cavity that is formed to cause input exhaust stream106to make one or more turns. The one or more turns lead to a reduction of a noise content of exhaust stream106.

For instance,FIG. 3shows a cross-sectional view of an exhaust silencer300, which is an example of exhaust silencer202. As shown inFIG. 3, exhaust silencer300includes a body302, a cavity304in body302, a baffle plate306that partially divides cavity304, an inlet port308, and an outlet port310. Inlet port308is formed in a first surface312of body302. Outlet port310is formed in a second surface314of body. Inlet port308receives exhaust stream106from exhaust port104of microturbine102. Outlet port310discharges exhaust stream204.

Body302and baffle plate306may be constructed from a variety of materials, such as a metal, a combination of metals/alloy or a ceramic material. For example, in an embodiment, body302and/or baffle plate306may be made of stainless or galvanized steel (e.g., 10-gauge or 16-gauge galvanized steel). As shown inFIG. 3, baffle plate306partially divides cavity304, to form first and second longitudinal compartments318and320in body302. Inlet308opens to a first end of first compartment318. An opening322is present between first and second compartments318and320at a second end of first compartment318and a first end of second compartment320. Outlet310is open at a second end of second compartment320. Thus, in the example ofFIG. 3, baffle plate306is positioned in cavity304to create a u-shaped compartment (the combination of first and second compartments318and320, and opening322) in body302, to create a u-shaped path for exhaust gas to flow through body302.

As shown in the example ofFIG. 3, first and second surfaces312and314are perpendicular surfaces to each other. In other embodiments, inlet port308and outlet port310may be located in the same surface (e.g., surface314), in opposing surfaces (e.g., surfaces312and316), or in alternative locations of body302. Inlet port308and outlet port310are openings in body302, and may have any shape, including circular, rectangular, etc. Furthermore, inlet port308may include interfacing elements to interface with a source of exhaust stream106, including a sealing material, a seal ring, etc.

FIG. 4shows a flow of gases through exhaust silencer300. As shown inFIG. 4, inlet port308receives exhaust stream106(shown inFIG. 3), in a direction indicated by first arrow402. Exhaust stream106flows through cavity304along a u-shaped path indicated by arrows404,406, and408. Exhaust stream106passes through inlet port308(first arrow402) at a first end of first compartment318, and proceeds along the direction of second arrow404, having made a 90 degree turn. Exhaust stream106flows through first compartment318from the first end to the second end along second arrow404in a direction perpendicular to first arrow402. Exhaust stream106curves 180 degrees around an end of baffle plate306through opening322from first compartment318to second compartment320, as indicated by third arrow406. Exhaust stream106flows through second compartment320from the first end to the second end along fourth arrow408in a direction opposite to the direction of flow through first compartment318along second arrow404. Exhaust stream106flows out of outlet port310as exhaust stream204(shown inFIG. 3) in a direction indicated by fifth arrow410, which is the same direction as fourth arrow408. Thus, outlet port310is configured to discharge exhaust stream204from body302.

Thus, by flowing exhaust stream106around turns that are at least in part created by baffle plate306in cavity304, noise present in discharged exhaust stream204is reduced by exhaust silencer300. Baffle plate306absorbs at least some of the noise content. Baffle plate306may be configured to flex a desired amount to provide desired noise absorption. Although a 180 degree turn is shown inFIGS. 3 and 4(along with a 90 degree turn from first arrow402to second arrow404), further turns may be present in the exhaust silencers described herein. A turn may be 90 degrees, 180 degrees, or other angle. Furthermore, instead of a single u-shaped pattern, an s-shaped pattern (including a repeating s-shaped or undulating pattern) may be present in exhaust silencer300, as desired in a particular application, to provide further noise absorption.

FIGS. 5 and 6show views of an exhaust silencer500, which is a further example of exhaust silencer202shown inFIG. 2, according to an embodiment of the present invention.FIG. 5shows a cross-sectional view of exhaust silencer500, andFIG. 6shows a perspective view of exhaust silencer500. Exhaust silencer500is similar to exhaust silencer300shown inFIG. 3, with the addition of a discharge hood502, a screen504, and a collar506(screen504and outlet port310are not visible inFIG. 6). Discharge hood502projects out from body302over outlet port310to partially cover outlet port310. Discharge hood502is configured to protect outlet port310from environmental elements, such as rain, snow, etc. As shown inFIG. 5, an exhaust stream exiting from outlet port310is deflected at a slight angle downward from horizontal in a direction indicated by arrow508. Screen504screens an opening between an outer edge of discharge hood502and a bottom edge of outlet port310. Screen504further protects outlet port310from environmental elements, such as insects, birds, etc.

Collar506mounts body302on a surface510. Collar506may provide a more convenient interface with exhaust port104of microturbine102. Surface510may be a surface of a building, microturbine102, a floor, or other surface or structure. Collar506further provides an interface between inlet port308and a source of exhaust stream106, such as exhaust port104. Collar506may have any suitable shape, including a hollow tube shape, etc. Collar506may have a circular cross-section, rectangular cross-section, or other cross-sectional shape. Collar506may be made of a variety of materials, including those described above for body302and baffle plate306.

FIGS. 5 and 6shows various example dimensions for exhaust silencer500, including a height512of body302, a length514of body302, a width516of opening322, a width518of inlet port308, a distance520between an edge of collar506and an outer edge of body302, a width602of body302, a height604between surface312of body302and a bottom surface of baffle plate306, and a thickness606of baffle plate306. These dimensions can have a variety of values, depending on the particular application of exhaust silencer500. For example, in an embodiment, height512may be 14 inches, length514may be 46 inches, width516may be 10 inches, width518may be 10⅛ inches, distance520may be 34 inches, width602may be 23 inches, height604may be 7 inches, and thickness606may be 1 inch. These dimensions are provided for illustrative purposes, and are not intended to be limiting.

FIGS. 7 and 8show views of an exhaust silencer700, which is a further example of exhaust silencer202shown inFIG. 2, according to an embodiment of the present invention.FIG. 7shows a cross-sectional view of exhaust silencer700, andFIG. 8shows a top view of exhaust silencer700. Exhaust silencer700is similar to exhaust silencer300shown inFIG. 3, except for the configuration of outlet port310, and the addition of a second collar702and a mounting assembly704.

As shown inFIG. 7, inlet port308and outlet port310are on opposing surfaces (surfaces312and316, respectively) of body302. Outlet port310is positioned on top surface316of body302, rather than side surface314of body302, as shown inFIGS. 3 and 5. InFIG. 7, outlet port310is positioned such that it discharges exhaust stream204from second compartment320(which is a second longitudinal segment of cavity304, in addition to first compartment318) in a direction indicated by arrow706that is perpendicular to a flow of exhaust stream106through second compartment320(indicated by arrow408). In contrast, inFIG. 3, outlet port310is positioned such that it discharges exhaust stream204from second compartment320in a direction that is the same as the direction of the flow of exhaust stream106through second compartment320. InFIG. 7, the extra 90 degree turn of the exhaust stream due to the position of outlet port310on top surface316of body302can provide for further noise reduction by exhaust silencer700as compared to exhaust silencer300ofFIG. 3.

Second collar702is mounted to top surface316of body302as an additional outlet tube for outlet port310. As shown inFIG. 8, second collar702may be round in shape. However, second collar702may have other shapes, including rectangular, etc. As shown inFIGS. 7 and 8, inlet port308and outlet port310(and thus first collar506and second collar702) may be positioned coaxially on opposite sides of body302, although this is not necessary.

Mounting assembly704is used to provide mounting stability for exhaust silencer700on surface510(in addition to the mount provided by first collar506). In the example ofFIGS. 7 and 8, mounting assembly704includes a pair of mounts708aand708b,which are attached (e.g., screwed, riveted, bolted, and/or welded) to body302. Mounts708aand708bhave respective through-holes710aand710b. Mounting assembly704further includes a pair of I-bolts712(only one I-bolt is visible inFIG. 7), which respectively pass through through-holes710aand710band screw into surface510to mount exhaust silencer700to surface510. In alternative embodiments, mounting assembly may include other types and/or numbers of mounting elements, as needed for a particular application.

FIGS. 7 and 8show various example dimensions for exhaust silencer700, including a width714of second collar702, a distance716between an edge of second collar702and surface314of body302, a height718of first collar506, a distance802between centers of through-holes710aand710b,a longitudinal distance804between a center of through-hole710band a center of second collar702, a latitudinal distance806between a side surface of body302and the center of second collar702. These dimensions can have a variety of values, depending on the particular application of exhaust silencer700. For example, in an embodiment, width714may be 10⅛ (ten and one-eighth) inches, distance716may be 2 inches, height718may be 6 inches, distance802may be 25¾ (twenty-five and three-quarter) inches, distance804may be 38 inches, and distance806may be 11½ (eleven and one-half) inches. Furthermore, through-holes710aand710bmay have example diameters of ¾ (three-quarters) of an inch. Still further, the dimensional values provided above for exhaust silencer500can be applied to exhaust silencer700.

Note that the example dimensions described above may be varied as required for a particular application based on a variety of factors, including a pressure of exhaust stream106, a temperature of exhaust stream106, a size of microturbine102, etc.

FIG. 9shows a cross-sectional view of an exhaust silencer900, which is a further example of exhaust silencer202shown inFIG. 2, according to an embodiment of the present invention. Body902of exhaust silencer900inFIG. 9is similar to body302of exhaust silencer700shown inFIG. 7, except a layer904of material lines/covers an inner surface of cavity304and a top surface of baffle plate306. In embodiments, the material of layer904is a heat resistant material and/or a sound absorbing material. When a heat resistant material is used for layer904, the heat resistant material aids exhaust silencer900in withstanding a heat of exhaust stream106passing through cavity304. Exhaust stream106entering exhaust silencer900may have a temperature of 700 degrees F., for example. Thus, the heat resistant material is selected to be able to withstand such temperatures. When a sound absorbing material is used for layer904, the sound absorbing material further aids exhaust silencer900in reducing noise generated by microturbine102.

The material of layer904can be any suitable heat resistant and/or sound absorbing material. For example, in an embodiment, layer904may be an aluminum foam. Aluminum foam typically is sound absorbing, and in an example embodiment, may be heat resistant to 1000 degrees F.

Any portion of cavity304and/or baffle plate306may be lined/covered by layer904. For example, as shown inFIG. 9, a top surface of baffle plate306is covered by layer904, but a bottom surface of baffle plate306is not covered by layer904. This configuration may be used because an exhaust stream flowing into cavity304from inlet port308will be at the greatest temperature and greatest pressure, and baffle plate306may be better able to withstand the heat and pressure, rather than layer904. Furthermore, having layer904on the bottom surface of baffle plate306may interfere with the noise reduction characteristics of baffle plate306. Alternatively, however, in an embodiment, layer904may cover the bottom surface of baffle plate306.

FIG. 10shows a cross-sectional view of an exhaust silencer1000, which is a further example of exhaust silencer202shown inFIG. 2, according to an embodiment of the present invention. Exhaust silencer1000inFIG. 10is similar to exhaust silencer700shown inFIG. 7, except that exhaust silencer1000includes a cover1002for a top opening of second collar702. As shown inFIG. 10, cover1002can move between a first position1004and a second position1006(shown by dotted lines inFIG. 10). In first position1004, cover1002blocks outlet port310(e.g., by blocking an opening of second collar702). First position1004for cover1002provides for environmental protection for exhaust silencer1000, by blocking environmental elements from entering outlet port310, such as rain, snow, birds, insects, etc. In second position1006, cover1002does not block outlet port310. Thus, in second position1006, outlet port310is able to discharge exhaust stream204along the direction of arrow706.

Note that in embodiments, cover1002may be automatically (e.g., electrically, by computer instruction, etc.) or manually controlled to move between first and second positions1004and1006. Alternatively, cover1002may be configured to move between first and second positions1004and1006due to a pressure of exhaust stream204being discharged from outlet port310. For example, cover1002may be weighted to be capable of being moved/positioned by the exhaust stream.

Note that features of the various exhaust silencers described above can be combined in any manner, as desired for a particular application.

FIG. 11shows a flowchart100providing example steps for silencing an engine, according to example embodiments of the present invention. For example, the exhaust silencers described above can be used to perform flowchart1100. Flowchart1100is described as follows. Other structural and operational embodiments will be apparent to persons skilled in the relevant art(s) based on the following discussion.

Flowchart1100begins with step1102. In step1102, an exhaust stream is received at an inlet port of a body. For example, as shown inFIG. 3, exhaust stream106is received at inlet port308of body302of exhaust silencer300. In a similar fashion, exhaust silencers500,700,900, and1000receive exhaust stream106along arrow402at inlet port308.

In step1104, the exhaust stream flows around a baffle plate in a cavity of the body. For example, as shown inFIG. 4, exhaust stream106flows along the direction of arrows402,404,406,408, and410, around baffle plate306of exhaust silencer300. In a similar fashion, exhaust stream106flows along the direction of arrows402,404,406,408, and410, around baffle plate306for exhaust silencers500,700,900, and1000. Flowing around baffle plate306in cavity304reduces noise content for an exhaust stream.

In step1106, the exhaust stream is discharged from an outlet port of the body. For example, as shown inFIG. 3, exhaust stream204is discharged from outlet port310of body302of exhaust silencer300. In a similar fashion, exhaust silencers500,700,900, and1000discharge exhaust stream204along arrow410from outlet port310.

According to flowchart1100, noise produced by an engine, such as a microturbine, is reduced. Additional steps may be performed during flowchart1100, according to the teachings provided herein, as would be known to persons skilled in the relevant art(s).

For instance,FIG. 12shows a step1202that may be performed during step1104of flowchart1104. In step1202, the exhaust stream flows along a u-shaped path through the cavity formed by the baffle plate. For example, as shown for exhaust silencers300,500,700,900, and1000, baffle plate306creates a u-shaped path for flow of an exhaust stream. As described above, an exhaust silencer may have alternative and/or additional turns other than the u-shaped turn due to baffle plate306.

FIG. 13shows a step1302that may be performed in flowchart1100. In step1302, sound generated by the turbine is absorbed with a material that lines at least a portion of a surface of the cavity. For example, as described above with respect toFIG. 9, a layer904of material may line/cover an inner surface of cavity304and a surface of baffle plate306. The material of layer904may absorb sound and/or may be heat resistant. Any portion of cavity304and/or baffle plate306may be lined/covered by the material.

Conclusion