CA2693957A1 - Wear insert for use in a rotary atomizer - Google Patents
Wear insert for use in a rotary atomizer Download PDFInfo
- Publication number
- CA2693957A1 CA2693957A1 CA2693957A CA2693957A CA2693957A1 CA 2693957 A1 CA2693957 A1 CA 2693957A1 CA 2693957 A CA2693957 A CA 2693957A CA 2693957 A CA2693957 A CA 2693957A CA 2693957 A1 CA2693957 A1 CA 2693957A1
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- Canada
- Prior art keywords
- wear insert
- longitudinal channel
- slurry
- outlet end
- wear
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
- B05B3/00—Spraying or sprinkling apparatus with moving outlet elements or moving deflecting elements
- B05B3/02—Spraying or sprinkling apparatus with moving outlet elements or moving deflecting elements with rotating elements
- B05B3/10—Spraying or sprinkling apparatus with moving outlet elements or moving deflecting elements with rotating elements discharging over substantially the whole periphery of the rotating member, i.e. the spraying being effected by centrifugal forces
- B05B3/1007—Spraying or sprinkling apparatus with moving outlet elements or moving deflecting elements with rotating elements discharging over substantially the whole periphery of the rotating member, i.e. the spraying being effected by centrifugal forces characterised by the rotating member
- B05B3/1021—Spraying or sprinkling apparatus with moving outlet elements or moving deflecting elements with rotating elements discharging over substantially the whole periphery of the rotating member, i.e. the spraying being effected by centrifugal forces characterised by the rotating member with individual passages at its periphery
- B05B3/1028—Spraying or sprinkling apparatus with moving outlet elements or moving deflecting elements with rotating elements discharging over substantially the whole periphery of the rotating member, i.e. the spraying being effected by centrifugal forces characterised by the rotating member with individual passages at its periphery the passages comprising an insert
Abstract
A wear insert (22) for use in a rotary atomizer for atomizing a slurry to form a discharge spray. The wear insert comprises a hollow body having an open inlet end for receiving the slurry, an open outlet end for discharging the slurry, and a longitudinal channel (74) extending from the inlet end to the outlet end. The longitudinal channel includes a central axis and is provided for directing a stream of slurry therethrough from the inlet end to the outlet end. The longitudinal channel includes at least one substantially flat surface (82,86, 90,94) over which the slurry stream flows as it is directed through the longitudinal channel.
The stream of slurry is atomized to form a discharge spray as it exits the outlet end.
The stream of slurry is atomized to form a discharge spray as it exits the outlet end.
Description
WEAR INSERT FOR USE IN A ROTARY ATOMIZER
FIELD OF THE INVENTION
The present invention relates to a wear insert for use in a rotating atomizer wheel. The atomizer wheel may be arranged to be positioned within a chamber for use in connection with flue gas desulfurization. However, it should be understood that the wear insert of the present invention is not limited to use in connection with gas desulfurization. To the contrary, the wear insert of the present invention is not limited to flue gas desulfurization and can be utilized in spray drying processes in a broad range of other industries including pharmaceuticals, powdered milk, coffee, food products, and clay. For example, powdered milk results from passing liquid milk slurry through an atomizer wheel which flash evaporates the water from the slurry leaving a powdered milk product. The wear insert of the present invention provides a fan-shaped atomized spray exiting the wear insert having an increased width and a decreased depth which increases the efficiency of atomization, reduces usage of lime, improves desulfurization and increases wear insert life, among other benefits.
BACKGROUND OF INVENTION
Flue gas desulfurization systems are typically used in coal fired power plants, waste-to-energy plants and in incinerators. A typical desulfurization system will include a processing or treatment chamber wherein flue gases are subjected to desulfurization treatment. Positioned inside that chamber is a high speed rotating atomizer wheel through which a desulfurization treatment slurry is dispersed into the chamber and the gas therein in order to initiate the desulfurization process.
Typically, the atomizer wheels are circular with a circumferential sidewall that includes nozzle openings that project through the circumferential sidewall.
Typically, the atomizer wheels are between eight and fourteen inches in diameter.
Such a desulfurization system might typically be powered by drive systems that include motors in the 160 to 1100 horsepower range that rotate the atomizer wheels at speeds of 8,800-10,000 rpm and upwards to 15,000 rpm. While these wheels are rapidly rotating at these very high speeds, a slurry treatment mixture, typically of water, lime and other inert materials of upwards to 20%-40%
solids, is fed into the wheels at rates ranging typically between 40-200 gallons per minute.
Due to the rotational velocity of the wheels, the slurry fed into the wheels is accelerated and expelled through wear inserts positioned around the circumference of the rotating wheels into the treatment chamber. The atomized mist of the treatment slurry chemically reacts with the sulfur in the flue gases to form solid particles that precipitate from the flue gas. These solid particulates formed from the chemical reaction of the atomized treatment slurry and the flue gases are filtered out, thereby removing the sulfur from the flue gas.
A typical atomizer wheel that is the subject of the improvement of the present invention is shown in U.S. Patent No. 6,659,375. Atomizer wheels of a similar type are also disclosed in U.S. Patent Nos. 5,370,310; U.S. Re. Pat. No. 30,963 and U.S.
Pat. No. 5,356,075. In each of the atomizer wheels disclosed in these patents, the atomizer wheels are circular with a circumferential sidewall that forms a hollow center or annular space. Ejection orifices project through the circumferential sidewall. A lid or cover plate fits over the annular space. In the lid is an opening or inlet through which slurry to be atomized passes into the annular space. The atomizer wheel is positioned within a treatment chamber wherein atomized slurry from the wheel reacts with the gases in the chamber to desulfurize the gases.
The flow rate of slurry entering an atomizer wheel ranges from 40 to 200 gallons per minute. The number of wear inserts in an atomizer wheel range from six to forty and preferably range from eight to sixteen. The diameter of an atomizer wheel ranges from between six and fourteen inches, the smaller diameter atomizer wheels rotating at a faster rate (15,000 rpm) than the larger atomizer wheels.
Typically, smaller atomizer wheels are used for spray drying applications. Tip velocity, i.e., the angular velocity at the exit end of the wear insert, can range between 525 feet per second and 625 feet per second. The amount of slurry that can flow through a particular atomizer wheel is dependent upon the cross-sectional area of the internal passageway of the wear insert and the number of wear inserts on the atomizer wheel. Wear inserts for directing the flow of the atomized slurry from the atomizer wheel are well known in the art. These wear inserts are typically made of a wear-resistant sintered material such as boron carbide tungsten carbide, silicone carbide, aluminum oxide, and tetraboric carbide.
FIELD OF THE INVENTION
The present invention relates to a wear insert for use in a rotating atomizer wheel. The atomizer wheel may be arranged to be positioned within a chamber for use in connection with flue gas desulfurization. However, it should be understood that the wear insert of the present invention is not limited to use in connection with gas desulfurization. To the contrary, the wear insert of the present invention is not limited to flue gas desulfurization and can be utilized in spray drying processes in a broad range of other industries including pharmaceuticals, powdered milk, coffee, food products, and clay. For example, powdered milk results from passing liquid milk slurry through an atomizer wheel which flash evaporates the water from the slurry leaving a powdered milk product. The wear insert of the present invention provides a fan-shaped atomized spray exiting the wear insert having an increased width and a decreased depth which increases the efficiency of atomization, reduces usage of lime, improves desulfurization and increases wear insert life, among other benefits.
BACKGROUND OF INVENTION
Flue gas desulfurization systems are typically used in coal fired power plants, waste-to-energy plants and in incinerators. A typical desulfurization system will include a processing or treatment chamber wherein flue gases are subjected to desulfurization treatment. Positioned inside that chamber is a high speed rotating atomizer wheel through which a desulfurization treatment slurry is dispersed into the chamber and the gas therein in order to initiate the desulfurization process.
Typically, the atomizer wheels are circular with a circumferential sidewall that includes nozzle openings that project through the circumferential sidewall.
Typically, the atomizer wheels are between eight and fourteen inches in diameter.
Such a desulfurization system might typically be powered by drive systems that include motors in the 160 to 1100 horsepower range that rotate the atomizer wheels at speeds of 8,800-10,000 rpm and upwards to 15,000 rpm. While these wheels are rapidly rotating at these very high speeds, a slurry treatment mixture, typically of water, lime and other inert materials of upwards to 20%-40%
solids, is fed into the wheels at rates ranging typically between 40-200 gallons per minute.
Due to the rotational velocity of the wheels, the slurry fed into the wheels is accelerated and expelled through wear inserts positioned around the circumference of the rotating wheels into the treatment chamber. The atomized mist of the treatment slurry chemically reacts with the sulfur in the flue gases to form solid particles that precipitate from the flue gas. These solid particulates formed from the chemical reaction of the atomized treatment slurry and the flue gases are filtered out, thereby removing the sulfur from the flue gas.
A typical atomizer wheel that is the subject of the improvement of the present invention is shown in U.S. Patent No. 6,659,375. Atomizer wheels of a similar type are also disclosed in U.S. Patent Nos. 5,370,310; U.S. Re. Pat. No. 30,963 and U.S.
Pat. No. 5,356,075. In each of the atomizer wheels disclosed in these patents, the atomizer wheels are circular with a circumferential sidewall that forms a hollow center or annular space. Ejection orifices project through the circumferential sidewall. A lid or cover plate fits over the annular space. In the lid is an opening or inlet through which slurry to be atomized passes into the annular space. The atomizer wheel is positioned within a treatment chamber wherein atomized slurry from the wheel reacts with the gases in the chamber to desulfurize the gases.
The flow rate of slurry entering an atomizer wheel ranges from 40 to 200 gallons per minute. The number of wear inserts in an atomizer wheel range from six to forty and preferably range from eight to sixteen. The diameter of an atomizer wheel ranges from between six and fourteen inches, the smaller diameter atomizer wheels rotating at a faster rate (15,000 rpm) than the larger atomizer wheels.
Typically, smaller atomizer wheels are used for spray drying applications. Tip velocity, i.e., the angular velocity at the exit end of the wear insert, can range between 525 feet per second and 625 feet per second. The amount of slurry that can flow through a particular atomizer wheel is dependent upon the cross-sectional area of the internal passageway of the wear insert and the number of wear inserts on the atomizer wheel. Wear inserts for directing the flow of the atomized slurry from the atomizer wheel are well known in the art. These wear inserts are typically made of a wear-resistant sintered material such as boron carbide tungsten carbide, silicone carbide, aluminum oxide, and tetraboric carbide.
SUMMARY OF THE INVENTION
A wear insert for use in a rotary atomizer for atomizing a slurry to form a discharge spray. The wear insert comprises a hollow body having an open inlet end for receiving the slurry, an open outlet end for discharging the slurry, and a longitudinal channel extending from the inlet end to the outlet end. The longitudinal channel includes a central axis and is provided for directing a stream of slurry therethrough from the inlet end to the outlet end. The longitudinal channel includes at least one substantially flat surface over which the slurry stream flows as it is directed through the longitudinal channel. The stream of slurry is atomized to form a discharge spray as it exits the outlet end.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a cross-sectional view of a wear insert of the present invention situated within an atomizer wheel.
Fig. 2 is an elevational view of the outlet end of a prior art wear insert during use.
Fig. 3 is an elevational view of the outlet end of a wear insert of the present invention during use.
Fig. 4 is an elevational view of the outlet end of a wear insert of the present invention during use.
Fig. 5 is an elevational view of the outlet end of a prior art wear insert during use.
Fig. 6 is an elevational view of the outlet end of a prior art wear insert during use.
Fig. 7 is an elevational view of the outlet end of a wear insert of the present invention during use.
Fig. 8 is an elevational view of the outlet end of the prior art wear insert during use.
Fig. 9 is an elevational view of the outlet end of a wear insert of the present invention during use.
Fig. 10 is a graph comparing change in performance characteristics of the inventive wear insert with those of the prior art.
A wear insert for use in a rotary atomizer for atomizing a slurry to form a discharge spray. The wear insert comprises a hollow body having an open inlet end for receiving the slurry, an open outlet end for discharging the slurry, and a longitudinal channel extending from the inlet end to the outlet end. The longitudinal channel includes a central axis and is provided for directing a stream of slurry therethrough from the inlet end to the outlet end. The longitudinal channel includes at least one substantially flat surface over which the slurry stream flows as it is directed through the longitudinal channel. The stream of slurry is atomized to form a discharge spray as it exits the outlet end.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a cross-sectional view of a wear insert of the present invention situated within an atomizer wheel.
Fig. 2 is an elevational view of the outlet end of a prior art wear insert during use.
Fig. 3 is an elevational view of the outlet end of a wear insert of the present invention during use.
Fig. 4 is an elevational view of the outlet end of a wear insert of the present invention during use.
Fig. 5 is an elevational view of the outlet end of a prior art wear insert during use.
Fig. 6 is an elevational view of the outlet end of a prior art wear insert during use.
Fig. 7 is an elevational view of the outlet end of a wear insert of the present invention during use.
Fig. 8 is an elevational view of the outlet end of the prior art wear insert during use.
Fig. 9 is an elevational view of the outlet end of a wear insert of the present invention during use.
Fig. 10 is a graph comparing change in performance characteristics of the inventive wear insert with those of the prior art.
Fig. 11 is a chart comparing change in performance characteristics of the inventive wear insert with those of the prior art.
DETAILED DESCRIPTION OF THE INVENTION
Referring now in detail to the various figures of the drawings wherein like reference characters refer to like parts, there is shown in Fig. 1, a nozzle 10 of the present invention positioned within an ejection orifice 14 located on the circumference of the sidewall of a rotating atomizer wheel 18. During operation, the atomizer wheel 18 rotate in a counterclockwise direction as indicated by the direction arrow 20. Alternatively, the atomizer wheel may rotate in a clockwise direction as shown in other drawings. The ejection orifice 14 is an opening extending on a radial line (not shown) from the axis of rotation (not shown) of the circular atomizer wheel 18. The nozzle 10 is comprised of two components: a wear insert 22 and a structural or metallic protective cup 26.
The cup 26 is formed of any suitable metal and is usually formed of the same material used to form the atomizer wheel 18, e.g., titanium or stainless steel. The cup 26 has a cylindrical outer diameter or outer surface 30, a cylindrical bore or inner surface 34, an open end 38 and a support wall 42. The outer surface 30 has an ring groove 46 and an annular mounting shoulder 50 which engages a shoulder 54 located on the ejection orifice 14 to hold the protective cup 26 within the atomizer wheel 18 during operation. Open end 38 is arranged to receive the wear insert and the support wall 42 is arranged to engage and retain the wear insert 22 and prevent it from being ejected during rotational movement of the atomizer wheel during operation. The wear insert 22 slips into and is affixed within, e.g., glued, the protective cup 26. An 0-ring 58 seated within the 0-ring groove 46 is provided to help seal the wear insert 22 and protective cup 26 within the atomizer wheel 18 and lock it in place. The wear insert 22 is fabricated of any suitable very hard substance, e.g., silicon carbide or boron carbide. In an alternative embodiment, the wear insert 22 may be retained within the ejection orifice 14 of the atomizer wheel 18 without the use of the protective cup 26.
The wear insert 22 has a cylindrical outer diameter or outer surface 62 and includes an inlet end 66, an outlet end 70 and a longitudinal channel 74 within the wear insert 22 extending from the inlet end 66 to the outlet end 70. As shown in Fig.
1, the longitudinal channel 74 flares outwardly from a smaller cross-sectional area at the inlet end 66 to a larger cross-sectional area at the outlet end 70.
Alternatively, the cross-sectional area of the longitudinal channel 74 can remain constant from the inlet end to the outlet end or can taper inwardly from a larger cross-sectional area to a smaller cross-sectional area from the inlet end to the outlet end, or can include other configurations. The support wall 42 of the cup 26 includes an axial aperture 78 that is approximately equal in size to the outlet end 70 of the wear insert 22.
Referring now to Fig. 3, there is shown an elevational view of a wear insert of the present invention at its outlet end 70. As shown in Fig. 3, the longitudinal channel 74 includes a central axis 142, and four substantially flat walls 82, 86, 90, and 94, the walls being of approximate equal length from end to end and being joined at their ends by rounded corners 98 approximating a square configuration. It is to be understood that the present invention is not limited to the configuration described and illustrated in the specification. Rather, the invention includes configurations having at least one substantially flat wall. For example, the longitudinal channel 74 could include four flat walls of unequal length forming a rectangle or quadrilateral. Alternatively, the longitudinal channel 74 could include five or more flat walls, e.g., forming a pentagon or hexagon, the walls having equal or unequal length. Alternatively, the longitudinal channel 74 could include a single flat wall with the remainder of the longitudinal channel cross-section being rounded, e.g., semicircular.
Referring now to Fig. 2, there is shown a prior art wear insert 102. Such known wear inserts 102 include a guide tube 106 having a circular cross-section through which a slurry stream passes. On known wear inserts, the cross-sectional area of the guide tube remains constant from the inlet end to the outlet end.
Known wear inserts may have other configurations. Rotational movement of the atomizer wheel 18 in which the wear insert 102 is affixed creates centrifugal forces which direct the slurry 122 to occupy only a portion of the cross-section of the guide tube 106, i.e., the side surface the guide tube 106, as the slurry 122 flows across the guide tube 106 from the inlet end to the outlet end. The slurry 122 itself comprises a predetermined cross-sectional area and is shown filling only about 25% of the cross-sectional area of the guide tube 106 of the prior art wear insert 102. Thus, the amount of slurry 122 flowing through the guide tube 106 of the prior art wear insert 102 is less than full capacity. Wear is typically observed over time during service which is caused by the laminar and turbulent flow conditions of the slurry 122 along the side surface of the guide tube 106. Such wear creates performance problems due to the fact that geometrical changes in the wear insert tend to affect the atomizer spray efficiency.
The prior art wear inserts suffer from several drawbacks. As best shown in Fig. 5, the centrifugal forces caused by rotation of the atomizer wheel 18 during operation, cause large lime (and/or fly ash particles) 126 of the slurry to settle out of the water portion 130 of the slurry and to bunch together against the side surface of the guide tube 106 of the prior art wear insert 102. The largest numbers of these lime particles 126 settle at the mid-point of the side surface while fewer particles settling above and below the mid-point. In Fig. 5, thirty-four discrete lime particles 126 are shown bunched together at the side surface of the guide tube 106, each particle exerting a force in an amount of 1 F against the side surface due to centrifugal force. At the mid-point of the bunch, the lime particles 126 are stacked three or four deep and exert a force against the side surface of the guide tube 106 in an aggregate amount of as much as 3F or 4F while above and below the mid-point, where lime particles 126 are stacked not as deep, a lesser aggregate force of 1 F or 2F is exerted.
Figs. 6 and 8 illustrate the manner in which the geometry of the prior art wear insert 102 changes over time as the lime particles 126 continue to exert forces and progressively wear away the side surface of the guide tube106. As best shown in these figures, as wear progresses, the stacking of lime particles 126 upon themselves actually increases, thus accelerating the progression of wear. As shown in Fig. 6, the lime particles 126 have worn away the side surface of the guide tube 106 of the known wear insert 102 to form a bulbous wear area indicated at 132.
As shown in Fig. 8, over time, the lime particles 126 continue to wear away the side surface of the guide tube 106 of the prior art wear insert 102 to form a wear cone 134. As wear builds on the side surface of the prior art wear insert 102, the fan-shaped atomized spray exiting the outlet end thereof becomes narrower and deeper resulting in lower efficiency of desulfurization and requiring increased usage of lime and more frequent maintenance.
Referring again to Fig. 8, when the wear insert has reached a predetermined level of wear, e.g., when the wear cone 134 has fully formed, or when a predetermined period of time has expired, the atomizer wheel 18 is shut down to enable rotation of the wear insert 102 along its central axis 138 to a new position to distribute wear evenly around the remaining surface of the circular guide tube 106.
For example, the wear insert 102 can be rotated about its central axis 138 to four distinct service positions, 900 apart from each other. Alternatively, the wear insert 102 can be rotated to three distinct service positions, 120 apart from each other, or to two service positions, 180 apart from each other. Once the wear insert is rotated a full 360 , it is removed and replaced with a new unworn wear insert. If the rotation is not performed in time, wear will progress and the rate of wear will increase rapidly due to the shape of the wear cone. Over time, wear can progress through the wear insert 102 and protective cup and can extend into the atomizer wheel which can result in catastrophic failure.
Referring again to Fig. 3, in order to overcome the shortcomings associated with the prior art wear inserts 102, the inventive wear insert 22 is provided with a longitudinal channel 74 having a plurality of flat side walls, 82, 86, 90, and 94. Figs.
3, 4, 7 and 9 illustrate the manner in which the geometry of the longitudinal channel 74 of the inventive wear insert 22 changes over time as the lime particles 126 continue to exert forces against the flat side wall 82 of the longitudinal channel 74.
As shown in Fig. 3, rotational movement of the atomizer wheel 18 in which the inventive wear insert 22 is affixed forces the slurry 122 to occupy only a portion of the cross-section of the longitudinal channel 74, i.e., the flat side wall 82.
As shown in Fig. 3, the same predetermined cross-sectional area of slurry 122 as is shown in the prior art wear insert 102 of Fig. 2 occupies an even smaller portion of the cross-section of the longitudinal channel 74 of the inventive wear insert 22. The slurry 122 is more evenly distributed due to the geometry of the flat side wall 82.
Referring now to Fig. 4, the same thirty-four lime particles 126 are shown evenly distributed, one-deep, across the length of a flat side wall 82 of the longitudinal channel 74, each particle 126 exerting a force in the amount of 1 F
against the flat side wall 82. Significantly, the lime particles 126 are not stacked two, three and four deep as they are in the prior art wear insert 102 of Fig. 5.
Thus, forces causing wear are less and are distributed evenly along the length of the flat side wall 82.
Referring now to Figs. 7 and 9, due to the geometry of the flat side wall 82, forces caused by lime particles 126 are distributed more uniformly across the flat surface and the progression of wear along flat side wall 82 occurs and a much reduced rate, thus substantially increasing service life and reducing down time of the atomizer wheel 18 for replacing wear inserts. As shown in Figs. 7 and 9, the progression of wear demonstrated by the inventive wear insert 22 is relatively small when compared with that of the prior art wear insert 102. The reduction in length of the flat side wall 82 of the inventive wear insert 22 due to wear is minimal and the amount of stacking of lime particles 126 occurs, if at all, only at the ends of the flat side wall 82 and is minimal. Like the prior art wear insert 102, the inventive wear insert 22 can be rotated about its central axis 142 to new positions to distribute wear evenly to remaining walls 86, 90 and 94 of the longitudinal channel 74.
As best shown in Fig. 10, due to the resulting geometry of the inventive wear insert 22, the overall width of the atomized spray exiting the wear insert 22 is greater than that produced by the prior art wear insert 102. Such greater width of spray results in greater efficiency of atomization which improves desulfurization.
Fig. 10 also demonstrates that the reduction in width of the atomized spray due to increasing wear on the inventive wear insert 22 over time is substantially less than that caused by wear on the prior art wear insert 102, resulting in longer life and greater efficiency and consistency of atomization which improves desulfurization. Likewise, as best shown in Fig. 11, the overall depth of the atomized spray resulting from the geometry of the inventive wear insert 22 is substantially less than that produced by the prior art wear insert 102, resulting in the same benefits as previously mentioned.
Moreover, as demonstrated in this figure, the increase in depth of the atomized spray caused by wear on the inventive wear insert 22 is substantially less than that caused by wear on the prior art wear insert 102 resulting in a longer life of the wear insert and greater efficiency of atomization. While the invention has been described in detail and with reference to specific examples thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.
An alternative embodiment 110 of the wear insert of the present invention is shown in Fig. 12. This wear insert 110 includes a longitudinal channel 114 being in the shape of a cone, the longitudinal channel 114 flaring outwardly from the inlet end 118 to the outlet end 122. The resulting atomized spray is greater in width and lesser in depth than that produced by the prior art wear insert 102 due to the flared geometry of the longitudinal channel 114. Also, wear over time is reduced because forces causing wear are distributed over a greater surface at the outlet end 122 of the wear insert 110.
DETAILED DESCRIPTION OF THE INVENTION
Referring now in detail to the various figures of the drawings wherein like reference characters refer to like parts, there is shown in Fig. 1, a nozzle 10 of the present invention positioned within an ejection orifice 14 located on the circumference of the sidewall of a rotating atomizer wheel 18. During operation, the atomizer wheel 18 rotate in a counterclockwise direction as indicated by the direction arrow 20. Alternatively, the atomizer wheel may rotate in a clockwise direction as shown in other drawings. The ejection orifice 14 is an opening extending on a radial line (not shown) from the axis of rotation (not shown) of the circular atomizer wheel 18. The nozzle 10 is comprised of two components: a wear insert 22 and a structural or metallic protective cup 26.
The cup 26 is formed of any suitable metal and is usually formed of the same material used to form the atomizer wheel 18, e.g., titanium or stainless steel. The cup 26 has a cylindrical outer diameter or outer surface 30, a cylindrical bore or inner surface 34, an open end 38 and a support wall 42. The outer surface 30 has an ring groove 46 and an annular mounting shoulder 50 which engages a shoulder 54 located on the ejection orifice 14 to hold the protective cup 26 within the atomizer wheel 18 during operation. Open end 38 is arranged to receive the wear insert and the support wall 42 is arranged to engage and retain the wear insert 22 and prevent it from being ejected during rotational movement of the atomizer wheel during operation. The wear insert 22 slips into and is affixed within, e.g., glued, the protective cup 26. An 0-ring 58 seated within the 0-ring groove 46 is provided to help seal the wear insert 22 and protective cup 26 within the atomizer wheel 18 and lock it in place. The wear insert 22 is fabricated of any suitable very hard substance, e.g., silicon carbide or boron carbide. In an alternative embodiment, the wear insert 22 may be retained within the ejection orifice 14 of the atomizer wheel 18 without the use of the protective cup 26.
The wear insert 22 has a cylindrical outer diameter or outer surface 62 and includes an inlet end 66, an outlet end 70 and a longitudinal channel 74 within the wear insert 22 extending from the inlet end 66 to the outlet end 70. As shown in Fig.
1, the longitudinal channel 74 flares outwardly from a smaller cross-sectional area at the inlet end 66 to a larger cross-sectional area at the outlet end 70.
Alternatively, the cross-sectional area of the longitudinal channel 74 can remain constant from the inlet end to the outlet end or can taper inwardly from a larger cross-sectional area to a smaller cross-sectional area from the inlet end to the outlet end, or can include other configurations. The support wall 42 of the cup 26 includes an axial aperture 78 that is approximately equal in size to the outlet end 70 of the wear insert 22.
Referring now to Fig. 3, there is shown an elevational view of a wear insert of the present invention at its outlet end 70. As shown in Fig. 3, the longitudinal channel 74 includes a central axis 142, and four substantially flat walls 82, 86, 90, and 94, the walls being of approximate equal length from end to end and being joined at their ends by rounded corners 98 approximating a square configuration. It is to be understood that the present invention is not limited to the configuration described and illustrated in the specification. Rather, the invention includes configurations having at least one substantially flat wall. For example, the longitudinal channel 74 could include four flat walls of unequal length forming a rectangle or quadrilateral. Alternatively, the longitudinal channel 74 could include five or more flat walls, e.g., forming a pentagon or hexagon, the walls having equal or unequal length. Alternatively, the longitudinal channel 74 could include a single flat wall with the remainder of the longitudinal channel cross-section being rounded, e.g., semicircular.
Referring now to Fig. 2, there is shown a prior art wear insert 102. Such known wear inserts 102 include a guide tube 106 having a circular cross-section through which a slurry stream passes. On known wear inserts, the cross-sectional area of the guide tube remains constant from the inlet end to the outlet end.
Known wear inserts may have other configurations. Rotational movement of the atomizer wheel 18 in which the wear insert 102 is affixed creates centrifugal forces which direct the slurry 122 to occupy only a portion of the cross-section of the guide tube 106, i.e., the side surface the guide tube 106, as the slurry 122 flows across the guide tube 106 from the inlet end to the outlet end. The slurry 122 itself comprises a predetermined cross-sectional area and is shown filling only about 25% of the cross-sectional area of the guide tube 106 of the prior art wear insert 102. Thus, the amount of slurry 122 flowing through the guide tube 106 of the prior art wear insert 102 is less than full capacity. Wear is typically observed over time during service which is caused by the laminar and turbulent flow conditions of the slurry 122 along the side surface of the guide tube 106. Such wear creates performance problems due to the fact that geometrical changes in the wear insert tend to affect the atomizer spray efficiency.
The prior art wear inserts suffer from several drawbacks. As best shown in Fig. 5, the centrifugal forces caused by rotation of the atomizer wheel 18 during operation, cause large lime (and/or fly ash particles) 126 of the slurry to settle out of the water portion 130 of the slurry and to bunch together against the side surface of the guide tube 106 of the prior art wear insert 102. The largest numbers of these lime particles 126 settle at the mid-point of the side surface while fewer particles settling above and below the mid-point. In Fig. 5, thirty-four discrete lime particles 126 are shown bunched together at the side surface of the guide tube 106, each particle exerting a force in an amount of 1 F against the side surface due to centrifugal force. At the mid-point of the bunch, the lime particles 126 are stacked three or four deep and exert a force against the side surface of the guide tube 106 in an aggregate amount of as much as 3F or 4F while above and below the mid-point, where lime particles 126 are stacked not as deep, a lesser aggregate force of 1 F or 2F is exerted.
Figs. 6 and 8 illustrate the manner in which the geometry of the prior art wear insert 102 changes over time as the lime particles 126 continue to exert forces and progressively wear away the side surface of the guide tube106. As best shown in these figures, as wear progresses, the stacking of lime particles 126 upon themselves actually increases, thus accelerating the progression of wear. As shown in Fig. 6, the lime particles 126 have worn away the side surface of the guide tube 106 of the known wear insert 102 to form a bulbous wear area indicated at 132.
As shown in Fig. 8, over time, the lime particles 126 continue to wear away the side surface of the guide tube 106 of the prior art wear insert 102 to form a wear cone 134. As wear builds on the side surface of the prior art wear insert 102, the fan-shaped atomized spray exiting the outlet end thereof becomes narrower and deeper resulting in lower efficiency of desulfurization and requiring increased usage of lime and more frequent maintenance.
Referring again to Fig. 8, when the wear insert has reached a predetermined level of wear, e.g., when the wear cone 134 has fully formed, or when a predetermined period of time has expired, the atomizer wheel 18 is shut down to enable rotation of the wear insert 102 along its central axis 138 to a new position to distribute wear evenly around the remaining surface of the circular guide tube 106.
For example, the wear insert 102 can be rotated about its central axis 138 to four distinct service positions, 900 apart from each other. Alternatively, the wear insert 102 can be rotated to three distinct service positions, 120 apart from each other, or to two service positions, 180 apart from each other. Once the wear insert is rotated a full 360 , it is removed and replaced with a new unworn wear insert. If the rotation is not performed in time, wear will progress and the rate of wear will increase rapidly due to the shape of the wear cone. Over time, wear can progress through the wear insert 102 and protective cup and can extend into the atomizer wheel which can result in catastrophic failure.
Referring again to Fig. 3, in order to overcome the shortcomings associated with the prior art wear inserts 102, the inventive wear insert 22 is provided with a longitudinal channel 74 having a plurality of flat side walls, 82, 86, 90, and 94. Figs.
3, 4, 7 and 9 illustrate the manner in which the geometry of the longitudinal channel 74 of the inventive wear insert 22 changes over time as the lime particles 126 continue to exert forces against the flat side wall 82 of the longitudinal channel 74.
As shown in Fig. 3, rotational movement of the atomizer wheel 18 in which the inventive wear insert 22 is affixed forces the slurry 122 to occupy only a portion of the cross-section of the longitudinal channel 74, i.e., the flat side wall 82.
As shown in Fig. 3, the same predetermined cross-sectional area of slurry 122 as is shown in the prior art wear insert 102 of Fig. 2 occupies an even smaller portion of the cross-section of the longitudinal channel 74 of the inventive wear insert 22. The slurry 122 is more evenly distributed due to the geometry of the flat side wall 82.
Referring now to Fig. 4, the same thirty-four lime particles 126 are shown evenly distributed, one-deep, across the length of a flat side wall 82 of the longitudinal channel 74, each particle 126 exerting a force in the amount of 1 F
against the flat side wall 82. Significantly, the lime particles 126 are not stacked two, three and four deep as they are in the prior art wear insert 102 of Fig. 5.
Thus, forces causing wear are less and are distributed evenly along the length of the flat side wall 82.
Referring now to Figs. 7 and 9, due to the geometry of the flat side wall 82, forces caused by lime particles 126 are distributed more uniformly across the flat surface and the progression of wear along flat side wall 82 occurs and a much reduced rate, thus substantially increasing service life and reducing down time of the atomizer wheel 18 for replacing wear inserts. As shown in Figs. 7 and 9, the progression of wear demonstrated by the inventive wear insert 22 is relatively small when compared with that of the prior art wear insert 102. The reduction in length of the flat side wall 82 of the inventive wear insert 22 due to wear is minimal and the amount of stacking of lime particles 126 occurs, if at all, only at the ends of the flat side wall 82 and is minimal. Like the prior art wear insert 102, the inventive wear insert 22 can be rotated about its central axis 142 to new positions to distribute wear evenly to remaining walls 86, 90 and 94 of the longitudinal channel 74.
As best shown in Fig. 10, due to the resulting geometry of the inventive wear insert 22, the overall width of the atomized spray exiting the wear insert 22 is greater than that produced by the prior art wear insert 102. Such greater width of spray results in greater efficiency of atomization which improves desulfurization.
Fig. 10 also demonstrates that the reduction in width of the atomized spray due to increasing wear on the inventive wear insert 22 over time is substantially less than that caused by wear on the prior art wear insert 102, resulting in longer life and greater efficiency and consistency of atomization which improves desulfurization. Likewise, as best shown in Fig. 11, the overall depth of the atomized spray resulting from the geometry of the inventive wear insert 22 is substantially less than that produced by the prior art wear insert 102, resulting in the same benefits as previously mentioned.
Moreover, as demonstrated in this figure, the increase in depth of the atomized spray caused by wear on the inventive wear insert 22 is substantially less than that caused by wear on the prior art wear insert 102 resulting in a longer life of the wear insert and greater efficiency of atomization. While the invention has been described in detail and with reference to specific examples thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.
An alternative embodiment 110 of the wear insert of the present invention is shown in Fig. 12. This wear insert 110 includes a longitudinal channel 114 being in the shape of a cone, the longitudinal channel 114 flaring outwardly from the inlet end 118 to the outlet end 122. The resulting atomized spray is greater in width and lesser in depth than that produced by the prior art wear insert 102 due to the flared geometry of the longitudinal channel 114. Also, wear over time is reduced because forces causing wear are distributed over a greater surface at the outlet end 122 of the wear insert 110.
Claims (27)
1. A wear insert for use in a rotary atomizer for atomizing a slurry to form a discharge spray, said wear insert comprising:
a. a hollow body having an open inlet end for receiving the slurry, an open outlet end for discharging the slurry, and a longitudinal channel extending from said inlet end to said outlet end;
b. said longitudinal channel including a central axis and being provided for directing a stream of slurry therethrough from said inlet end to said outlet end, said longitudinal channel including at least one substantially flat surface over which said stream of slurry flows as it is directed through said longitudinal channel, the stream of slurry being atomized to form a discharge spray as it exits said outlet end.
a. a hollow body having an open inlet end for receiving the slurry, an open outlet end for discharging the slurry, and a longitudinal channel extending from said inlet end to said outlet end;
b. said longitudinal channel including a central axis and being provided for directing a stream of slurry therethrough from said inlet end to said outlet end, said longitudinal channel including at least one substantially flat surface over which said stream of slurry flows as it is directed through said longitudinal channel, the stream of slurry being atomized to form a discharge spray as it exits said outlet end.
2. The wear insert as claimed in claim 1 wherein said longitudinal channel has a substantially constant cross-sectional area from said inlet end to said outlet end.
3. The wear insert as claimed in claim 1 wherein said longitudinal channel has a cross-sectional area that increases from said inlet end to said outlet end.
4. The wear insert as claimed in claim 1 wherein said longitudinal channel has a cross-sectional area that decreases from said inlet end to said outlet end.
5. The wear insert as claimed in claim 1 wherein said substantially flat surface extends away from said central axis as said surface extends from said inlet end to said outlet end.
6. The wear insert as claimed in claim 1 wherein said longitudinal channel comprises a polygonal cross-section.
7. The wear insert as claimed in claim 6 wherein said longitudinal channel comprises a plurality of substantially flat surfaces, each said flat surface extending away from said central axis as said flat surface extends from said inlet end to said outlet end.
8. The wear insert as claimed in claim 6 wherein said longitudinal channel comprises four substantially flat surfaces forming a rectangular cross-section.
9. The wear insert as claimed in claim 8 wherein each of said four substantially flat surfaces extends away from said central axis as said flat surface extends from said inlet end to said outlet end.
10. The wear insert as claimed in claim 6 wherein said longitudinal channel comprises four substantially flat surfaces forming a substantially square cross-section.
11. The wear insert as claimed in claim 10 wherein each of said four substantially flat surfaces extends away from said central axis as said flat surface extends from said inlet end to said outlet end.
12. The wear insert as claimed in claim 6 wherein said longitudinal channel comprises three substantially flat surfaces forming a substantially triangular cross-section.
13. The wear insert as claimed in claim 12 wherein each of said three substantially flat surfaces extends away from said central axis as said flat surface extends from said inlet end to said outlet end.
14. The wear insert as claimed in claim 1 wherein said wear insert is comprised of a material selected from the group of materials consisting of boron carbide, silicon carbide, tool steel, heat treated stainless steel and carbide castings.
15. The wear insert as claimed in claim 1, said wear insert further comprising an outside surface that is of circular cross-sectional shape.
16. The wear insert as claimed in claim 1, said wear insert being formed of a wear resistant material.
17. The wear insert as claimed in claim 1, wherein said insert is utilized for flue gas desulfurization.
18. The wear insert as claimed in claim 1, wherein said insert is utilized in a spray drying process.
19. In combination with a rotary atomizer for use in connection with flue gas desulfurization, a wear insert comprising a hollow body having an open inlet end for receiving the slurry, an open outlet end for discharging the slurry, and a longitudinal channel extending from said inlet end to said outlet end, said longitudinal channel including a central axis and being provided for directing a stream of slurry therethrough from said inlet end to said outlet end, said longitudinal channel including at least one substantially flat surface over which said stream of slurry flows as it is directed through said longitudinal channel, the stream of slurry being atomized to form a discharge spray as it exits said outlet end, said rotary atomizer further comprising an atomizer wheel having a cylindrical wall containing at least one ejection orifice, said wear insert arranged to be retained within said ejection orifice.
20. The rotary atomizer of claim 17 additionally comprising a protective cup, said protective cup arranged to be retained within said ejection orifice and said wear insert being arranged to be retained within said protective cup.
21. The rotary atomizer of claim 17 wherein said wear insert is arranged to be retained within said ejection orifice without the use of a protective cup.
22. The rotary atomizer of claim 19 wherein said protective cup includes an outer surface including an O-ring groove for seating an O-ring therein.
23. The rotary atomizer of claim 19 wherein said protective cup includes a support wall arranged to engage and retain the wear insert therein during rotational movement of the atomizer wheel.
24. The rotary atomizer of claim 19 additionally comprising between eight and sixteen ejection orifices and a wear insert retained within each ejection orifice.
25. The rotary atomizer of claim 19 additionally comprising between two and forty ejection orifices and a wear insert retained within each ejection orifice.
26. The rotary atomizer of claim 20 wherein said protective cup includes an annular mounting shoulder arranged for engaging a shoulder located on the ejection orifice to hold the protective cup within the atomizer wheel during rotation.
27. A wear insert for use in a rotary atomizer for atomizing a slurry to form a discharge spray, said wear insert comprising:
a. a hollow body having an open inlet end for receiving the slurry, an open outlet end for discharging the slurry, and a longitudinal channel extending from said inlet end to said outlet end;
b. said longitudinal channel including a central axis and being provided for directing a stream of slurry therethrough from said inlet end to said outlet end, said longitudinal channel being in the shape of a cone, said cone flaring outwardly from said inlet end to said outlet end.
a. a hollow body having an open inlet end for receiving the slurry, an open outlet end for discharging the slurry, and a longitudinal channel extending from said inlet end to said outlet end;
b. said longitudinal channel including a central axis and being provided for directing a stream of slurry therethrough from said inlet end to said outlet end, said longitudinal channel being in the shape of a cone, said cone flaring outwardly from said inlet end to said outlet end.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US45878906A | 2006-07-20 | 2006-07-20 | |
| US11/458,789 | 2006-07-20 | ||
| PCT/US2007/070054 WO2008011228A1 (en) | 2006-07-20 | 2007-05-31 | Wear insert for use in a rotary atomizer |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2693957A1 true CA2693957A1 (en) | 2008-01-24 |
Family
ID=38596408
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA2693957A Abandoned CA2693957A1 (en) | 2006-07-20 | 2007-05-31 | Wear insert for use in a rotary atomizer |
Country Status (4)
| Country | Link |
|---|---|
| CN (1) | CN101626838A (en) |
| CA (1) | CA2693957A1 (en) |
| TW (1) | TW200808451A (en) |
| WO (1) | WO2008011228A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113390745A (en) * | 2021-08-17 | 2021-09-14 | 中国科学院、水利部成都山地灾害与环境研究所 | Double-shaft rolling type device and method for testing abrasion resistance of channel section form capable of being simulated |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10376809B2 (en) | 2012-12-20 | 2019-08-13 | Gea Process Engineering A/S | Insert for an atomizer wheel and atomizer wheel comprising a number of such inserts |
| CA2895397C (en) * | 2012-12-20 | 2018-03-20 | Gea Process Engineering A/S | Insert for an atomizer wheel and atomizer wheel comprising a number of such inserts |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2920830A (en) * | 1956-12-26 | 1960-01-12 | Niro Atomizer As | Atomizer for the atomization of liquid dispersions in a reaction chamber |
| DK117820B (en) * | 1965-03-26 | 1970-06-01 | Atomizer N Ak | Atomizer wheel for atomizing slurries of highly abrasive materials. |
| DE60017305T2 (en) * | 1999-03-24 | 2006-04-06 | Albemarle Netherlands B.V. | Atomizer wheel with improved nozzles for rotating atomizers |
-
2007
- 2007-05-31 CN CN200780034891A patent/CN101626838A/en active Pending
- 2007-05-31 WO PCT/US2007/070054 patent/WO2008011228A1/en active Search and Examination
- 2007-05-31 CA CA2693957A patent/CA2693957A1/en not_active Abandoned
- 2007-06-15 TW TW96121697A patent/TW200808451A/en unknown
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113390745A (en) * | 2021-08-17 | 2021-09-14 | 中国科学院、水利部成都山地灾害与环境研究所 | Double-shaft rolling type device and method for testing abrasion resistance of channel section form capable of being simulated |
| CN113390745B (en) * | 2021-08-17 | 2021-11-09 | 中国科学院、水利部成都山地灾害与环境研究所 | Double-shaft rolling type device and method for testing abrasion resistance of channel section form capable of being simulated |
Also Published As
| Publication number | Publication date |
|---|---|
| CN101626838A (en) | 2010-01-13 |
| WO2008011228A1 (en) | 2008-01-24 |
| TW200808451A (en) | 2008-02-16 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |
Effective date: 20130531 |