Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
  • F04D13/00—Pumping installations or systems
  • F04D13/02—Units comprising pumps and their driving means
  • F04D13/021—Units comprising pumps and their driving means containing a coupling
  • F04D13/024—Units comprising pumps and their driving means containing a coupling a magnetic coupling
  • F04D13/026—Details of the bearings
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
  • F04D23/00—Other rotary non-positive-displacement pumps
  • F04D23/008—Regenerative pumps
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
  • F01D25/00—Component parts, details, or accessories, not provided for in, or of interest apart from, other groups
  • F01D25/18—Lubricating arrangements
  • F01D25/22—Lubricating arrangements using working-fluid or other gaseous fluid as lubricant
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
  • F04D25/00—Pumping installations or systems
  • F04D25/02—Units comprising pumps and their driving means
  • F04D25/026—Units comprising pumps and their driving means with a magnetic coupling
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
  • F04D29/00—Details, component parts, or accessories
  • F04D29/40—Casings; Connections of working fluid
  • F04D29/52—Casings; Connections of working fluid for axial pumps
  • F04D29/522—Casings; Connections of working fluid for axial pumps especially adapted for elastic fluid pumps
  • F04D29/526—Details of the casing section radially opposing blade tips

Definitions

• the present invention relates to a rotary compressor for compressing a gaseous medium and a gas lubricated mechanical seal arrangement comprising such a rotary compressor as an auxiliary compressor.
• a rotary compressor having the features of claim 1 has an enhanced flow rate and enhanced pressure boosting.
• a rotary compressor comprises an impeller, a drive unit and a magnetic coupling for connecting the impeller with the drive unit.
• the impeller is designed as a solid, deflection-free disc.
• the impeller comprises a first row and a second row of blades, wherein the blades are separated by a circumferential middle wall. The blades of the first row are thereby offset in circumferential direction relative to the blades of the second row.
• the inventive rotary compressor provides a flushing gas flow after start up in case the main compressor is non-operative. Furthermore, since the magnetic coupling comprises a rotating inner rotor, a rotating outer rotor and a can, a hermetical sealing is provided and leakage of process gas towards the environment is excluded.
• the drive unit is preferably an electric drive unit or a hydraulic drive unit or a pneumatic drive unit.
• the rotary compressor comprises a housing having an inlet, an outlet and a flow path located at the outer circumference of the impeller.
• the flow path connects the inlet with the outlet and preferably comprises two tube-like, ring-shaped path elements.
• the cross section of the path elements in the housing is preferably a semi-circle.
• the flow path is provided around at least 300°, preferably 315°, of the outer circumference of the impeller.
• the flow path and/or the inlet and/or the outlet have a surface with a plurality of dimples.
• the dimples induce micro-turbulences, which enhance the flow characteristic.
• the dimples have a ring-like outer circumference and are designed as circular pits with approx 0,1 - 0,5 mm diameter and a depth of 25-30% of the diameter . Further, a uniform distribution of the dimples on the flow path and in- and outlet ports is preferred.
• the joint between inlet and/or outlet port and the flow path is shaped as a fillet, minimizing obstructions.
• the number of blades of the first row and the second row is identical. This supports a constant flow of the gaseous medium.
• the first and second row of blades are offset in circumferential direction by half of a length of one spacing between two neighbouring blades.
• the offset resembles an arc length of 4°.
• the blades are straight radial blades being slightly tapered in radial direction.
• the barrier can of the magnetic coupling comprises an inner barrier and an outer barrier, wherein an electrostatic insulation layer is arranged between the inner and outer barrier in order to prevent electrostatically induced arcing.
• the electrostatic insulation layer is made of a synthetic material, preferably polyimide.
• the inner barrier consists preferably of an alternating stack of metal rings and PTFE insulation foil.
• the outer barrier can comprises longitudinal slots. The arrangement of inner- and outer barrier can reduce magnetic eddy currents, providing low energy consumption and a highly efficient magnetic coupling. Heat generation is reduced.
• the rotary compressor comprises a bearing unit.
• the bearing unit comprises an upper and lower bearing.
• the lower bearing is a double bearing whereas the upper is a single bearing.
• the bearings are angular contact ball bearings, so that a precise axial positioning of the impeller shaft and the impeller can be provided.
• a circumferential distance between neighbouring blades of the impeller is 10° arc length or less.
• a thickness of the middle wall of the impeller is the same as a thickness of the blades at an outermost portion of the blades.
• a gas supply unit comprising a main compressor and an auxiliary compressor, wherein the auxiliary compressor is a rotary compressor according to the invention.
• the inventive gas lubricated mechanical seal arrangement is operable under special conditions like stopping of the main gas supply system or working under low system pressure conditions. Due to the use of the inventive rotary compressor-long maintaining intervals and a reliable, leakage-free operation and a non-leakage can be achieved. As further advantage standard electric motors can be used to drive the impeller.
• Fig. 1 is a cross section of a rotary compressor according to one embodiment of the invention
• Fig. 5 a total view of the rotary compressor including a motor
• the rotary compressor 1 according to a preferred embodiment of the invention comprises an impeller 2, an electric motor 3 and a magnetic coupling 4.
• the magnetic coupling 4 connects the electric motor 3 with the impeller 2.
• the magnetic coupling 4 comprises a can 40, an inner rotor 41 and an outer rotor 42.
• the outer rotor 42 is connected with the electric motor 3 and the inner rotor 41 is connected via an impeller shaft 6 with the impeller 2.
• the impeller 2 comprises a central opening 26 (see Fig. 4) to accommodate an end of the impeller shaft 6.
• the magnetic coupling 4 is protected by a cover 14.
• the can 40 comprises an inner barrier 43, an outer barrier 44 and an electrostatic insulation layer 45. f he electrostatic insulation layer 45 is arranged between the inner and outer barrier in order to prevent electric arcing.
• the electrostatic insulation layer 45 is, for example, made of polyimide.
• the rotary compressor 1 further comprises a housing 7 with a first housing part 71 and a second housing part 72.
• the can 40 is fixed to the second housing part 72, e.g. by means of bolts.
• the housing 7 accommodates a flow path 5, with a ring-like path surrounding the impeller 2 partly.
• the flow path 5 is defined between an inlet 8 and an outlet 9 and covers approximately 315°. That is, an angle a between the inlet and the outlet is approximately 45°.
• the flow path 5 comprises a first portion 51 and a second portion 52.
• the first and second portion have the shape of semi-circles with equal radii.
• the radii of the first and second portion 51 , 52 and the contour of the spacings 24 provided between neighbouring blades 23 of the impeller 2 merge into a closed volute channel.
• the housing 7 is attached to a base plate 0 by means of which the rotary compressor 1 can be fixed to any structural part.
• the impeller shaft 6 is supported by a first bearing 11 and a second bearing 12.
• the first bearing 11 is a double bearing provided by angular contact ball bearings. Thereby, the first bearing 11 is the bearing being located closer to the impeller 2 in an axial direction X-X (see Fig. 1 ).
• pressure balancing bores 13 are provided in order to achieve a pressure equilibrium between bearing unit inside and outside.
• the impeller 2 is shown in detail in Figs. 2 to 4.
• the impeller 2 comprises a first row 21 of blades and a second row 22 of blades.
• the first row and the second row of blades have the same number of blades 23. Neighbouring blades are separated by spacings 24, respectively.
• the first row 21 of blades is offset in circumferential direction with regard to the second row 22 of blades.
• the two rows of blades are offset by half of an arc length of one spacing 24, i.e. 4°.
• the first row 21 and the second row 22 of blades 23 are separated in axial direction by means of a middle wall 20.
• a thickness at the outer circumferential portion of the middle wall 20 is thereby the same as a thickness of the blades 23 at the outermost end of the blades 23.
• the impeller 2 further comprises a solid portion 25 which connects the central opening 26 and the two rows of blades. Thus, the impeller has a deflection-free disc.
• the impeller shaft 6 is connected with the impeller 2 by means of a key and slot arrangement.
• dimples may be provided on the first and second portion 51 , 52 of the flow path 5. The dimples enhance the flow characteristic and thereby can improve a the flow rate provided by the rotary compressor 1 and, thus, improve the pressure boosting.
• a coating, like PTFE, of the flow path 5 can further enhance the flow rate.
• at the transition between the flow path 5 with the inlet 8 and the outlet 9 features a smooth transition to minimize obstructions in the gas flow path in the housing 7.
• Fig. 7 shows a preferred use of the inventive rotary compressor 1 in a gas lubricated mechanical seal arrangement 100.
• the arrangement 100 comprises a mechanical seal having a rotating seal ring 101 connected to a shaft 15 and a stationary seal ring 102 connected to a stationary element.
• a sealing gap 103 is formed between the two sealing rings 101 , 102.
• the mechanical seal separates a product side 113 from an atmosphere side 114 by means of a gaseous medium provided by a main compressor 105 via a seal gas supply 106.
• a filter 110 In the seal gas supply 106 there are provided a filter 110, a stop valve 108, an orifice 111 and a check valve 112.
• a bypass 107 which comprises a stop valve 109 and a rotary compressor 1 according to the invention.
• the bypass 107 bypasses thereby the stop valve 108, the orifice 111 and the check valve 112 (see Fig. 7).
• a labyrinth seal 104 neighbouring the rotating seal ring 101 in order to keep supplied gaseous medium 116 close to the sealing gap 103.
• the inventive rotary compressor 1 is activated as an auxiliary compressor in order to maintain the supply of gaseous medium 1 16 to the mechanical seal.
• the stop valve 108 is closed and the stop valve 109 is opened so that the gaseous medium is sucked through the bypass 107.
• the inventive rotary compressor 1 has a very short start-up time and can provide a non- pulsating gas flow to the mechanical seal. Due to the inventive configuration of the impeller 2, the flow path 5 and the magnetic coupling 4, a very efficient gas supply can be provided in a continuous matter and without gas leakage to the atmosphere. Thus, a contamination of the sealing gap 103 between the seal rings 101 , 102 can be avoided. Thereby, the inventive rotary compressor 1 can be run over a long time, since there is no friction and the danger of building up heat at the impeller 2. Furthermore, there is no risk of mechanical failure as it was the case when piston compressors were used.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Structures Of Non-Positive Displacement Pumps (AREA)

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Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

Country Status (9)

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Citations (4)

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• 2011
  • 2011-12-13 PL PL11009817T patent/PL2604863T3/pl unknown
  • 2011-12-13 EP EP11009817.5A patent/EP2604863B1/en not_active Not-in-force
• 2012
  • 2012-10-18 BR BR112014014489A patent/BR112014014489A2/pt not_active IP Right Cessation
  • 2012-10-18 CA CA 2861214 patent/CA2861214A1/en not_active Abandoned
  • 2012-10-18 WO PCT/EP2012/004363 patent/WO2013087130A1/en active Application Filing
  • 2012-10-18 CN CN201280061463.8A patent/CN104093987A/zh active Pending
  • 2012-10-18 US US14/363,026 patent/US20150125324A1/en not_active Abandoned
  • 2012-10-18 AU AU2012350434A patent/AU2012350434B2/en not_active Ceased
  • 2012-10-18 MX MX2014007008A patent/MX356243B/es active IP Right Grant

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