Manila
Perth Johannesburg
Sydney
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Problems With Conventional Slurry Pumps
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Conventional Pump Design
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Slurry Natural Recirculation Path
High Pressure
Low Pressure
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Uneven Parts Replacement Cycles
Suction Side Liners and Impellers wear 2 to 3 times Faster than Pump
Cases.
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Importance of Cyclone Performance
15
Summary of Conventional Pump Problems
• Wear ring takes up clearance at the impeller.
• Adjusted during operation.
• Reduces suction side recirculation.
• Maintains hydraulic performance.
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External Wear Adjustment Screws
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Krebs millMAX Pump Solving the Recirculation Problem
A Wide
B Tight
C Narrow
• Wide clearances at “A” prevents solids from being crushed. • Tight clearances at “B” prevents suction-side recirculation. • Narrow clearances at “C” ensures shaft sealing system works well.
38
Slurry Pump Application
39
Oversized pumps misalign flow
Below BEP Operation
Mismatch between Critical Flow Angles and Impeller Vanes
At BEP Operation
Incoming Angle of Slurry is Matched to Impeller Vane Angle
7
Conventional flow recirculation based on clearance versus pump speed
CLEARANCE 1400 RPM 1700 RPM
.300 mm
3.52%
4.03%
.432 mm
6.06%
6.65%
.508 mm
7.92%
8.62%
.737 mm
the Rear
Wide
Narrow
Step No. 2 (During Operation)
Set Front Clearance by Adjusting Wear
Ring Toward Impeller
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Setting Clearances
Adjustments Can be Done Throughout the Service Life of the Parts:
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33
HIGH PRESSURE/HIGH HEAD PUMPS
4 x 3-17 6 x 4-21
34
6x4x21 High Pressure Pump 35
6x4x21 High Pressure Pump 36
graveIMAX
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gravelMAX Pump
Solids Passing Size Comparison
• Slurry recirculation on the suction side • Grinding of solids between the impeller and suction liner • Reduced hydraulic efficiency (Er) • Reduced (cyclone) performance over time • High power consumption • Low parts wear life • Unequal maintenance cycles • Unscheduled shutdowns • Ball chips or tramp jams the impeller front or back side • Inability to increase capacity using existing motors and drives
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millMAX Bearing Assembly Design
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Reverse Taper Roller Bearings
• Increases Effective Load Span to Improve Life.
• Main Bearing Failure is Due to Over Greasing.
10
Effects of Suction-Side Recirculation
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Suction-Side Recirculation
Wide Gap at the Front and Back
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Grinding of Solids between the Impeller and Suction Liner or Throat Bush
Size
6x4x16 8x6x24 10x8x27 12x10x34
gravelMAX Warman
2•75" (68m) 3•2" (81 mm)
5" (127 mm) 5•5" (140 mm) 6" (152 mm) 7" (178 mm) 7" (178 mm) 8•26" (210 mm)
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millMAX Design
3x2 thru 14x12 • Incorporates a backliner • Solid volute case • Wear Ring adjustment thru
the casing • Water flush, centrifugal seal
and vacuum-pressure gland
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Impeller High Radial Vanes
• Clears large solids. • Prevents solids
from being crushed. • Reduces differential
pressure at the eye of the impeller.
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Adjustable Wear Ring
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millMAX Design Concept
• Patented on-line suction side wear clearance adjustment
• Hybrid Sealing System maintains constant flow and pressure without increasing speed or causing motor overload.
• Pumping Action of Taper Rollers Discharges Grease to the Outside Preventing Ingress of Slurry or Over Greasing of Bearing Cartridge.
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slurryMAX Pump
• While the pump is running. • Without disconnecting the drive. • Without moving the impeller and
shaft assembly. • Without disturbing guards or v-
belt drive.
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Patented “Hybrid” Sealing System
• Urethane carrier provides a seal against the intrusion of slurry.
• Long wearing high chrome iron wear ring seals against impeller.
18
millMAX Large Pump Design
16x14 thru 28x26 • Incorporates a suction
liner • Casing with suction plate • Wear ring adjustment thru
the suction liner • Water flush gland
Cv= 24.6%
Reference: University of Kentucky Hydraulics Laboratory
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Solids are Crushed Between Impellerand Pump Case, Consuming Power and Producing Wear
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Typical Wear Pattern on Worn Impeller
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millMAX Power Frame
• Heavy Duty Cast Pedestal • External Bearing Assembly Adjustment • Wide Bearing Centers • Heavy Duty Shaft and Bearings • Double Clamps