AU736872B2 - Pump impeller and method - Google Patents

Pump impeller and method Download PDF

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Publication number
AU736872B2
AU736872B2 AU87933/98A AU8793398A AU736872B2 AU 736872 B2 AU736872 B2 AU 736872B2 AU 87933/98 A AU87933/98 A AU 87933/98A AU 8793398 A AU8793398 A AU 8793398A AU 736872 B2 AU736872 B2 AU 736872B2
Authority
AU
Australia
Prior art keywords
impeller
outer diameter
shroud
pump
shrouds
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.)
Ceased
Application number
AU87933/98A
Other versions
AU8793398A (en
Inventor
Kevin Edward Burgess
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Weir Minerals Australia Ltd
Original Assignee
Warman International Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Priority claimed from AUPO8794A external-priority patent/AUPO879497A0/en
Application filed by Warman International Ltd filed Critical Warman International Ltd
Priority to AU87933/98A priority Critical patent/AU736872B2/en
Publication of AU8793398A publication Critical patent/AU8793398A/en
Application granted granted Critical
Publication of AU736872B2 publication Critical patent/AU736872B2/en
Assigned to WEIR WARMAN LTD reassignment WEIR WARMAN LTD Request to Amend Deed and Register Assignors: WARMAN INTERNATIONAL LIMITED
Assigned to WEIR MINERALS AUSTRALIA LTD reassignment WEIR MINERALS AUSTRALIA LTD Request to Amend Deed and Register Assignors: WEIR WARMAN LTD
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04DNON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00Details, component parts, or accessories
    • F04D29/18Rotors
    • F04D29/22Rotors specially for centrifugal pumps
    • F04D29/2205Conventional flow pattern
    • F04D29/2216Shape, geometry
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00Metal working
    • Y10T29/49Method of mechanical manufacture
    • Y10T29/49316Impeller making
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00Metal working
    • Y10T29/49Method of mechanical manufacture
    • Y10T29/49316Impeller making
    • Y10T29/49329Centrifugal blower or fan

Landscapes

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

Description

WO 99/10657 PCT/AU98/00677 -1- PUMP IMPELLER AND METHOD This invention relates generally to pumps and more particular, but not exclusively to high specific speed pumps.
The invention is particularly applicable to high specific speed pumps typically used for flue gas desulphurisation (FGD) applications in power stations. Such pumps are utilised in wet limestone scrubbing process to circulate the slurry to remove the sulphur from the flue gases before the sulphur can enter the atmosphere. Reference to this particular application is not to be taken as a limitation to the scope of the invention. It will be readily apparent to those persons skilled in the art that the invention is also applicable to other applications.
Pumps required for FGD applications typically must deliver high flowrate at moderate to low head. To achieve this they can, for example, be direct coupled which increases the speed at which they operate above say a lower speed gearbox driven pump. These higher speed pumps for FGD applications can also be referred to as a mixed flow pump, as opposed to say a normal slower running radial style of slurry pump. The flow in a radial pump is predominantly radial, whereas a mixed flow pump, the flow is both radial and axial.
The duty specifications for FGD pumps are normally very stringent and users require high efficiency. For FGD plants to operate correctly and efficiently, the FGD pumps must pump a precise set volume of limestone slurry through the FGD system. As the volume flowrate needs to be set precisely, so does the head (or pressure) that the pump supplies.
Normally, the pump specification does not allow any negative tolerances eg., if the specified pump head is 25m, then on test, the pump must produce 25m or more. How much more is also normally spelt out in the Pump Test Standard Acceptance Criteria that are given in the contract. This can be say +5 more head.
Design of a pump for FGD must take account of the duty requirements, particularly in regard to head as it is the head, which ultimately controls the volume flow of slurry in the P:\WPDOCS\DYSspcick7463903AUSPE.doc-7 Junc 2001 -2- FGD system. With a direct driven mixed flow pump, the impeller diameter can only be changed marginally to meet the duty requirements. Hence there will be occasions that the pump would generate more head than the specified and in some cases even more than the allowable upper limit specified in the contract. When the head is higher than the allowable tolerance, it must be reduced so the final tested head is within the tolerance band to meet the acceptance criteria.
To reduce the head to within the allowable tolerance (say to +5 the impeller can be modified by causing it to be trimmed i.e. a small reduction is made to the impeller diameter. Trimming to reduce the head also changes the power absorbed by the pump and this impacts on the pump efficiency.
The currently known technique as detailed in technical papers and texts is to make an angled cut on the drive side or rear shroud side of the impeller. This is shown in Figure 1.
15 Depending on the amount of trim (diameter reduction), the head and power are affected at different rates as shown in Figure 2. Hence while the prediction of the necessary trim is complicated, the main problem relates to the fact that the head and power reductions do not follow the same pattern. Hence, trimming by this known method generally results in a reduction in head, a lesser reduction in power and a consequential decrease in efficiency.
Hence it may occur that the head and flow produced by the pump are correct, but that the power absorbed is higher than the allowable tolerance. In such a case, the pump would be unacceptable.
It is an object according to one aspect of the present invention to provide a method of S 25 modifying a pump impeller so that it alleviates the problems discussed above.
It is a further object according to another aspect of the present invention to provide an improved pump impeller.
According to one aspect of the present invention there is provided a method of
PA
P:\WPOOCS\DYS\spede\74639)3AUSPE.dO,-7 2001 3,modifying a mixed flow pump impeller so as to achieve selected operating performance parameters, the impeller including a front shroud and a rear shroud, the shrouds being spaced apart so as to form a plurality of passageways therebetween which are separated by a plurality of impeller blades, each having an outer edge extending between the front and rear shrouds, the impeller having an outer diameter D, the method including the steps of trimming the outer edge of the impeller blades so that the outer diameter D 1 of the front shroud is less than the outer diameter D 2 of the rear shroud.
Preferably, the outer peripheral edge is trimmed so as to taper inwardly from the outer diameter D 2 of the rear shroud to the outer diameter D 1 of the front shroud.
According to another aspect of the present invention there is provided a mixed flow pump impeller including a front shroud having an outer diameter D 1 and a rear shroud having an outer diameter D 2 the shrouds being spaced apart so as to form a plurality of passageways 15 therebetween which are separated by a plurality of impeller blades each having an outer edge extending between the front and rear shrouds characterised in that the outer diameter D, of othe front shroud is less than the outer diameter D 2 of the rear shroud.
Preferably, the ratio of D,/D 2 ranges from between 1.0 to and including 0.85.
has been surprisingly discovered that the reduction in head and power follows a more predictable pattern and more importantly, the reduction in head and power achieved for any trim are more equal. The effect is that the pump efficiency is far less effected by the trim as compared to the known method. Hence it is more likely using the new method of S 25 impeller trimming, that the head and flow can be achieved within tolerance and at the same time that the efficiency is likewise acceptable.
0
PAT
WO 99/10657 PCT/AU98/00677 -4- Preferred embodiments of the invention will hereinafter be described with reference to the accompanying drawings and in those drawings Figure 1 is a schematic partial view of an impeller which has been trimmed using a known trimming technique; Figure 2 is a graph illustrating the general performance characteristics of the impeller shown in Figure 1; Figure 3 is a schematic partial view of an impeller which has been trimmed according to the present invention; and Figure 4 is a graph illustrating the general performance characteristics of the impeller shown in Figure 3 where percent trim is determined by
D
100 D x 100 2 Referring to Figures 1 and 3 there is shown two impellers each generally indicated at each impeller including a front shroud 12 and a rear shroud 14 with a series of blades extending therebetween separating the interior of the impeller into a series of passageways.
The impeller further includes a impeller inlet 17 and a series of outlets between the blades at the peripheral edge 19 of the impeller. The diameter of the front shroud is indicated by D, and the diameter of the rear shroud is indicated by In the prior art arrangement shown in Figure 1, the trimming is effected by removal of a portion of the outer peripheral edge so that the diameter of the inlet shroud D, is greater than the diameter of the outlet shroud D 2 As mentioned earlier, depending on the amount of trim (diameter reduction), the head and power effected at different rates as shown in Figure 2.
According to the present invention, the impeller is trimmed by removing material so that the diameter of the front shroud is less than the diameter of the rear shroud. The effect of this trimming is shown in Figure 4.
WO 99/10657 PCT/AU98/00677 Thus, according to the present invention, the pump efficiency is far less effected by the trimming operation as compared to the prior art method. As such it is more likely that under the method according to the present invention, the head and flow can be achieved within tolerance at the same time that the efficiency is held within acceptable limits.
Finally, it is to be understood that various alterations, modifications and/or additions may be incorporated into the various constructions and arrangements of parts without departing from the spirit or ambit of the invention.

Claims (8)

1. A method of modifying a mixed flow pump impeller so as to achieve selected operating performance parameters, the impeller including a front shroud and a rear shroud, the shrouds being spaced apart so as to form a plurality of passageways therebetween which are separated by a plurality of impeller blades, each having an outer edge extending between the front and rear shrouds, the impeller having an outer diameter D, the method including the steps of trimming the outer edge of the impeller blades so that the outer diameter D, of the front shroud is less than the outer diameter D 2 of the rear shroud.
2. A method according to claim 1 wherein the outer peripheral edge is trimmed so as to taper inwardly from the outer diameter D 2 of the rear shroud to the outer diameter D, of the front shroud.
3. A method according to claim 1 or claim 2 wherein the ration of D,/D 2 ranges from between 1.0 to and including 0.85. oo
4. A method according to any preceding claim wherein the pump impeller is for a pump use for fluid gas desulphurisation.
5. A mixed flow pump impeller including a front shroud having an outer diameter D, and o: a rear shroud having an outer diameter D 2 the shrouds being spaced apart so as to form a plurality of passageways therebetween which are separated by a plurality of impeller blades .each having an outer edge extending between the front and rear shrouds characterised in that •the outer diameter D, of the front shroud is less than the outer diameter D 2 of the rear shroud.
6. An impeller according to claim 5 wherein the ratio of D,/D 2 ranges from between to and including 0.85. An impeller according to claim 5 or claim 6 wherein outer edge is trimmed so as to P N (w LU- P:\WPDOCS\DYS\spccic\7463903AUSPE.doc-7 June 2001 -7- taper inwardly from the outer diameter D 2 of the rear shroud to the outer diameter D, of the front shroud.
8. An impeller according to any one of claims 5 to 7 wherein the impeller is used as a pump for fluid gas desulphurisation.
9. A method of modifying a mixed flow pump impeller substantially as hereinbefore described with reference to the accompanying drawings. A mixed flow pump impeller substantially as hereinbefore described with reference to the accompanying drawings. Dated this 7 th day of June, 2001 WARMAN INTERNATIONAL LIMITED By Its Patent Attorneys S: DAVIES COLLISON CAVE C U- AT *o
AU87933/98A 1997-08-26 1998-08-24 Pump impeller and method Ceased AU736872B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU87933/98A AU736872B2 (en) 1997-08-26 1998-08-24 Pump impeller and method

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
AUPO8794A AUPO879497A0 (en) 1997-08-26 1997-08-26 Pump impeller and method
AUPO8794 1997-08-26
PCT/AU1998/000677 WO1999010657A1 (en) 1997-08-26 1998-08-24 Pump impeller and method
AU87933/98A AU736872B2 (en) 1997-08-26 1998-08-24 Pump impeller and method

Publications (2)

Publication Number Publication Date
AU8793398A AU8793398A (en) 1999-03-16
AU736872B2 true AU736872B2 (en) 2001-08-02

Family

ID=25640952

Family Applications (1)

Application Number Title Priority Date Filing Date
AU87933/98A Ceased AU736872B2 (en) 1997-08-26 1998-08-24 Pump impeller and method

Country Status (1)

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AU (1) AU736872B2 (en)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH169128A (en) * 1933-05-08 1934-05-15 Escher Wyss Maschf Ag Gyroscope.
SU531929A1 (en) * 1973-03-19 1976-10-15 Предприятие П/Я А-7075 Impeller of centrifugal fan
SU1605035A1 (en) * 1988-10-30 1990-11-07 Предприятие П/Я В-8534 Centrifugal pump

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH169128A (en) * 1933-05-08 1934-05-15 Escher Wyss Maschf Ag Gyroscope.
SU531929A1 (en) * 1973-03-19 1976-10-15 Предприятие П/Я А-7075 Impeller of centrifugal fan
SU1605035A1 (en) * 1988-10-30 1990-11-07 Предприятие П/Я В-8534 Centrifugal pump

Also Published As

Publication number Publication date
AU8793398A (en) 1999-03-16

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HB Alteration of name in register

Owner name: WEIR WARMAN LTD

Free format text: FORMER NAME WAS: WARMAN INTERNATIONAL LIMITED