Patent Application
20130209251
The present disclosure concerns a seal arrangement in a bore (stuffing box) and around a shaft of a liquid ring pump. The arrangement is radially inward of a primary bearing assembly. The arrangement can provide a secondary bearing support.
Liquid ring pumps are well known. In a known liquid ring pump water or other liquid is introduced into the pump and centrifugally flung outwardly by a rotating rotor to form an annular ring of liquid with the stationary pump housing. The liquid ring rotates within the housing and is centered about the longitudinal axis of the housing. The rotational axis of the rotor, however, is offset from the axis of the housing. Consequently as the liquid ring rotates with the rotor, an air core, pocket or chamber is formed within the liquid ring. The inner diameter of the liquid ring is centered relative to the housing's axis but offset from and eccentric relative to the pump's shaft axis. The liquid volume in the housing is maintained to provide a seal at the outer portions of the rotor blades isolating individual chambers or buckets between adjacent rotor blades. At one point during a complete rotation of the rotor, the bucket or chamber is almost empty of liquid. As the rotor advances, liquid will fill the chamber. As the rotor further advances liquid will recede from the chamber until the chamber is almost empty again. As the liquid recedes from the chamber, it is replaced by air or other gas entering through the inlet of the pump. Then as the liquid is forced back into the chamber or bucket, the air is compressed and exits through the outlet of the pump.
U.S. Pat. No. 4,850,808, Schultze, discloses a liquid ring pump. The pump is conically ported (conical liquid ring pump) and has two stages. The pump includes a housing; a rotor assembly within the housing; a shaft extending into the housing on which the rotor assembly is fixedly mounted; and a motor assembly coupled to the shaft. During operation, the housing is partially filled with operating liquid so that when the rotor is rotating, the rotor blades engage the operating or pumping liquid and cause it to form an eccentric ring that converges and diverges in the radial direction relative to the shaft. Where the liquid is diverging from the shaft, the resulting reduced pressure in the spaces between adjacent rotor blades of the rotor assembly (buckets) constitutes a gas intake zone. Where the liquid is converging towards the shaft, the resulting increased pressure in the spaces between adjacent rotor blades (buckets) constitutes a gas compression zone. A cone shaped sleeve is mated within a cone shaped bore of the rotor assembly. The cone shaped sleeve is ported to allow gas that would otherwise be carried over from the compression zone, to bypass the intake zone and re-enter the compression zone.
U.S. Pat. No. 4,747,752, Somarakis, discloses a secondary bearing in a bore of a liquid ring pump. The bore is formed by the head and cone of the liquid ring pump. A lip seal is in the bore. The lip seal is axially outward of the secondary bearing. A plate or flange extending in the radial direction, at an axial outward end of the bore is coupled to an axial outward surface of the head forming the bore. The plate or flange abuts the lip seal and prevents the seal and secondary bearing from moving outward in the axial direction. A flange extending in the radial direction, at an axial inward end of the bore, abuts the secondary bearing. The flange prevents the lip seal and secondary bearing from moving radially inward. The lip seal and secondary bearing are fixed relative to the head and cone. Operating liquid enters and exits the bore
Prior art
The housing includes a central portion 30 that has an interior surface 32 that forms a cylindrical chamber 34 around the rotor 16. The cylindrical chamber can also be called a working chamber. The intake zone 20 and compression zone 24 form the working chamber. A first head 36 is coupled to a first axial end 38 of the central portion 30 and is at the first axial end of the working chamber. The first head 36, which can also be called a first cover, is at the outboard end of the liquid ring pump 10. The housing has another cover 40 coupled to a second axial end 42 of the central portion 30. The cover, which can also be called a second cover or a power end cover, is at the second axial end of the working chamber. The cover is at the power end of the liquid ring pump. If the pump were a two stage pump the cover would be a second head. The axis of the shaft 14 is offset, eccentric, relative to the axis of the central portion 30.
A first primary bearing support 44 is coupled to an axially outward facing side 46 of the first head 36. A first primary bore 48 is formed in the first bearing support 44. The shaft 14 extends into the first primary bore 48. A first primary bearing assembly 50, which can also be called an outboard bearing assembly, is disposed in the first primary bore 48 and around the shaft 14. Axially inward of the first primary bearing assembly is a first secondary bore 52.
The first secondary bore 52 can be called a first stuffing box. The first secondary bore is formed in the first head 36. The shaft 14 extends through the first secondary bore 52. A first packing 54 is in the first secondary bore 52 and around the shaft 14. The packing 54 includes seals 56 extending circumferentially around the shaft 14. The seals are rope seals. Axially between the rope seals 56 is a lantern seal 58 which also forms part of the packing. A packing gland 60, axially outward of the packing 54, pushes and squeezes the packing axially inward to abut up against flanges 62 that extend in the radial and axial direction at an axial inward end of the first secondary bore 52. The gland 60 abuts the packing 54. The gland is coupled to the head to overlap the axially outward facing side 46 of the primary head by fasteners 67. The gland 60 fixes the packing 54 against moving in the axial direction and holds the packing in place. The packing 54 and gland 60 are fixed relative to the head 36. The packing is within the bore 52. The gland is partially in the bore 52. The shaft 14 rotates within the packing 54 and relative to the packing. The lantern seal 58 is fluidly connected to a supply of liquid. During operation of the pump, the lantern seal allows for liquid to enter and be distributed between the packing and shaft to provide lubrication and a sealing function to prevent escape of air or gas from the working chamber into bore 52.
A cone 84 coupled to the first head 36 extends axially inward from an axially inward facing side 86 of the first head. The cone 84 is coupled to the first head 36. The cone extends into a complimentary bore formed by the rotor 16.
A second primary bearing support 64 is coupled to an axially outward facing side 66 of the power end cover 40. A second primary bore 68 is formed in the second primary bearing support 64. The shaft 14 extends into the second primary bore 68. A second primary bearing assembly 70, which can also be called a power end bearing assembly, is disposed in the second primary bore 68 and around the shaft 14. Axially inward of the second primary bearing assembly is a second secondary bore 72. The second secondary bore can be called a second stuffing box. The second secondary bore 72 is formed in the power end cover 40. The shaft 14 extends through the second secondary bore 72. A second packing 74 is in the second secondary bore 72 and around the shaft 14. The packing 74 includes seals 76 extending circumferentially around the shaft 14. The seals are rope seals. Axially between the rope seals 76 is a lantern seal 78 which also forms part of the packing 74. A packing gland 80, axially outward of the packing 74, pushes and squeezes the packing axially inward to abut up against flanges 82 that extend in the radial direction at an axial inward end of the second secondary bore 72. The gland 80 abuts the packing. The gland 80 is coupled to the housing to overlap an axially outward facing side 66 of the power end cover 40 by fasteners 67. The gland 80 fixes the packing 74 so that it does not move in the axial outward direction and holds the packing in place. The packing 74 and gland 80 are fixed relative to the cover 40. The packing is within the bore 72. The gland is partially in the bore 72. The shaft 14 rotates within the packing 74 and relative to the packing. The lantern seal 78 is fluidly connected to a supply of liquid. The lantern seal 78 allows for liquid to enter and be distributed between the packing 74 and shaft 14 to provide lubrication and a sealing function to prevent escape of air or gas from the working chamber into the bore 72.
The glands 60 and 80 are partially within their respective bores and partially extending axially out ward from their respective bores.
the cross section is taken along a plane parallel to the shaft; the cross section does not pass through the shaft.
An example of the invention is embodied in a liquid ring pump that has a housing with a longitudinally extending axis. The pump has a shaft with a longitudinal axis parallel to said housing's axis and offset therefrom. The shaft extends into the housing. A working chamber is formed in the housing. An inlet is formed in said housing and fluidly connected to the working chamber. An outlet is formed in the housing and fluidly connected to the working chamber. A rotor is fixedly coupled to the shaft and rotatable within the working chamber. A first bore is formed in the liquid ring pump. The shaft is in the first bore. A second bore is formed in the pump and is axially inward of the first bore. A first and second seal are in the second bore and around the shaft. The second seal is axially outward of the first seal. The second seal is the axially most outward seal in the bore. The second seal is free of an abutment axially outward of it and abutting up against it.
In a further example of the invention the second seal includes a first sleeve and a second sleeve. The first and second sleeves are coupled to one another and rotate relative to one another. The shaft extends through an opening formed by the first sleeve and contacts the first sleeve. The first sleeve is fixed relative to the shaft and during operation of the pump rotates with the shaft. The second sleeve contacts a surface of the pump which forms the second bore, and during operation of the pump, the second sleeve does not rotate relative to the surface of the pump it contacts.
The invention further includes a method of retrofitting a liquid ring pump. The liquid ring pump retrofit has a portion having a bore formed therein. At least one seal is in the bore. The seal is held in place by an abutment removeably coupled to the portion of the pump forming the bore to overlap an axially outward facing surface of the portion of the pump forming the bore. The method includes removing the abutment holding said seal in place. At least one seal is removed from the bore. A seal is placed in the bore. The seal is placed in the bore axially outward of another seal in the bore. The seal placed in the bore is left free of an abutment axially outward of it and abutting up against it.
The pump of
To facilitate the flow of liquid between the composite seal 100 and the shaft 214, the seal 100 has grooves, through holes and at least one slot therein. See
The seal 100, at a second axial end, has a second radially outer circumferential groove 116 or channel along its outer surface. At the same second axial end, it has a second radially inner circumferential groove 118 or channel along its inner surface. The second inner 118 and second outer 116 grooves are radially opposite each other. The second outer groove is bounded in the radially inward direction by second circumferential seal portion 120. The inner groove 118 is also bounded in the radial outward direction by the second circumferential seal portion 120. A series of through holes 122 extend through the second circumferential seal portion 120 to fluidly connect the second outer groove 116 to the second inner groove 118.
A series of axially extending channels 124 fluidly connect the first inner circumferential channel 110 to the second inner circumferential channel 118. The axially extending channels do not extend through the composite seal. A slot 126 extends axially from the first outer circumferential groove 108 and is fluidly connected thereto. The slot 126 does not extend through the composite seal.
As seen in
The first circumferential ring or sleeve 128 has an axially extending flange 134. The axially extending flange 134 forms a ring or collar around the shaft 214. The shaft extends through the ring 128. The flange 134 includes an elastomeric material 136 facing radially inward and contacting the shaft 214. The axially extending flange 134 thus abuts up against the shaft in a fixed manner and rotates with the shaft 214 during operation of the pump. The first circumferential ring or sleeve 128 has a radially extending flange 137 extending from the axially extending flange 134. The radially extending flange 137 forms the axially outward surface 106 bounding the axial outward end of the first secondary bore (the first stuffing box) 252. It provides the most axial outward surface of the seal arrangement 100, 102. The cassette seal 102 and composite seal 100 remain fixed from moving along the shaft 214 in an axially outward direction without the need for an axial outward abutment contacting the axial outward surface 106 of the cassette seal. The abutment eliminated includes a gland, end plate or flange, coupled to the housing to overlap an axially outward facing side 246 of the head 236. The abutment eliminated would abut the axially most outward surface 106 of the seal arrangement and cassette seal.
The second circumferential ring or sleeve 130 has an axially extending flange 138. The axially extending flange 138 can be called a second axially extending flange 138. The second axially extending flange forms a ring or collar around the first axially extending flange 134. The second flange 138 includes an elastomeric material 140 facing radially outward and contacting the surface of the first head 236 circumscribing the first stuffing box 252. The second axially extending flange 138 thus abuts up against the head 236 in a fixed manner and does not rotate relative to the head 236 during operation of the pump and rotation of the shaft 214. The second circumferential ring 130 has a radially extending flange 142 extending radially inward from the second axially extending flange 138. The radially extending flange 142 can be considered a second radially extending flange 142. The second radially extending flange 142 is axially inward of the first radially extending flange 137. During operation of the pump 210 and rotation of the shaft 214, the first axially extending flange 134 rotates relative to the second axially extending flange 138.
Having described the construction, function and advantages of the retrofit seal arrangement, for completeness, the construction of the pump 210 shown in
The housing includes central portion 230 that has an interior surface 232 that forms the cylindrical chamber 234 around the rotor 216. The cylindrical chamber can also be called a working chamber 234. The intake zone 220 and compression zone 224 form the working chamber. The first head 236 is coupled to the first axial end 238 of the central portion 230 and is at the first axial end of the working chamber. The first head, which can also be called a first cover, is at the outboard end of the liquid ring pump 210. The housing has another cover 240 coupled to a second axial end 242 of the central portion 230. The cover 240, which can also be called a second cover 240 or a power end cover 240, is at the second axial end of the working chamber. The cover is at the power end of the liquid ring pump. If the pump 210 were a two stage pump the cover would be a second head. The central portion has an axis extending in the axial direction. The shaft's longitudinal axis is parallel to the central portion's axis extending in the axial direction. The shaft's axis is offset, eccentric, relative to the central portion's axis.
A first primary bearing support 244 is coupled to the axially outward facing side 246 of the first head. A first primary bore 248 is formed in the first bearing support 244. The shaft 214 extends into the first primary bore 248. A first primary bearing assembly 250, which can also be called an outboard bearing assembly, is disposed in the first primary bore 248 and around the shaft 214. Axially inward of the first primary bearing assembly 250 is the first secondary bore 252. The first secondary bore 252 is also called the first stuffing box 252. The first secondary bore 252 is formed in the first head 236. The shaft 214 extends through the first secondary bore 252. The seal arrangement formed by the cassette seal 102 and composite seal 100 is in the first secondary bore 252 and around the shaft 214. A cone 284, coupled to the first head 236, extends axially inward from an axially inward facing side 286 of the first head. The cone 284 is coupled to the first head 236. The cone extends into a complimentary bore formed by the rotor 216. Although the seal arrangement has been described as being within a bore formed in the first head 236, it could alternatively be in a bore formed by the cone 284 or a bore formed by the cone 284 and head 236. The shaft of course would extend through the alternative bore.
A second primary bearing support 264 is coupled to an axially outward facing side 266 of the power end cover 240. A second primary bore 268 is formed in the second primary bearing support 264. The shaft 214 extends into the second primary bore 268. A second primary bearing assembly 270, which can also be called a power end bearing assembly, is disposed in the second primary bore 268 and around the shaft 214. Axially inward of the second primary bearing assembly 270 is a second secondary bore 272. The second secondary bore can be called a second stuffing box 272. The second secondary bore 272 is formed in the power end cover 240. The shaft 214 extends through the second secondary bore 272. A second packing 274 is in the second secondary bore 272 and around the shaft 214. The packing includes seals 276 extending circumferentially around the shaft 214. The seals are rope seals. Axially between the rope seals is a lantern seal 278 which also forms part of the packing. A packing gland 280, axially outward of the packing 274, pushes and squeezes the packing axially inward to abut up against flanges 282 that extend in the radial direction at an axial inward end of the second secondary bore 272. The gland 280 abuts the packing. The gland is coupled, by fasteners 267, to the head to overlap the axially outward facing side 266 of the power end cover 240. The gland 280 fixes the packing and prevents the packing from moving in the axial outward direction and holds the packing in place. The packing and gland are fixed relative to the cover 240. The packing is within the bore. The gland is partially in the bore. The shaft 214 rotates within the packing 274 and relative to the packing. The lantern seal 278 is fluidly connected to a supply of liquid. The lantern seal 278 allows for liquid to enter and be distributed between the packing 274 and shaft 214 to provide lubrication and a sealing function to prevent escape of air or gas from the working chamber 234 into the bore 272.
Although
Although the invention has been described in the context of a conical liquid ring pump it is equally applicable to a flat sided liquid ring pump.
The phrases “axially outward” and “axially inward” have meanings which are ascertainable by their context. The phrase axially inward can mean the relative location of one item compared to another item. For example one item can be more towards the center of the shaft along the axis than the other item. The phrase axially outward can mean the relative location of one item compared to another item. For example one item can be more away from the center of the shaft along the axis than the other item.
The phrases “axial direction” and “radial direction” have meanings which are ascertainable by their context. The phrase axially direction can mean the direction relative to the axis of the shaft. The phrase radial direction can mean the direction relative to axis of the shaft.
All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.
Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.
The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.
