Metso - Slurry Pumping

The industrial pump family Pumps Centrifugal pumps Displacement pumps Slurry pump Water pump Piston pump Membrane pump Gear pump Peristaltic pump (Hose pump) “A pump is a machine that conveys energy to a liquid” Slurry Pumping Basic Training Course

Slurry pump functions Displacement pumps “High pressures and moderate flows” Slurry Pumping Basic Training Course

Slurry pump functions Centrifugal pumps “Variable pressure and flow” Slurry Pumping Basic Training Course

Mechanics of slurry pumps Basic designs Horizontal Vertical - sump Vertical - tank Impeller Pump housing Shaft seal Bearing Drive system No Shaft Seal ! Slurry Pumping Basic Training Course

Mechanics of slurry pumps The impeller VT VN VR “Conveying energy from the pump shaft to the liquid and accelerates it” Slurry Pumping Basic Training Course

Semi Open Impeller (O) Not so sensitive against blockage by BIG particles and air. Can be a good selection when pumping very thick slurry, frothy slurry (air). Lower efficiency relative to Closed impeller Normally used in vertical sump and tank pumps Slurry Pumping Basic Training Course

Closed Impeller (C) Better efficiency More sensitive to blocking by big particle and air Small impellers are even more sensitive to blocking Always use Closed impellers for pumping dense and abrasive slurries Slurry Pumping Basic Training Course

Closed Impeller (C) ~ High efficiency impeller, “Low” wear Slurry Pumping Basic Training Course

Vortex Impeller Also called Induced Flow Prevents blocking when pumping larger particles, fibers and “sticky material” More gentle pumping if particles are easily damaged (carbon particles) Relatively low efficiency Slurry Pumping Basic Training Course

Number of Vanes (for Slurry Pumps) More vanes give higher efficiency…………. In practice max. 5 otherwise risk of blocking! ! Slurry Pumping Basic Training Course

Impeller Width Greater width gives a higher flow at fixed speed When pumping Bigger particles (Ex. Dredge applications) Slurry Pumping Basic Training Course

Impeller Diameter Larger impeller diameter gives lower RPM. But lower efficiency. Good for high-wear applications. Smaller impeller diameter and higher RPM gives better efficiency but greater wear. Good for pumping water and low wear slurries. Slurry Pumping Basic Training Course

Mechanics of slurry pumps Pump housing “Converts kinetic energy to hydraulic pressure” Whole pump housing Split pump housing Slurry Pumping Basic Training Course

Mechanics of slurry pumps Shaft seals Flushed Dynamic Mechanical (Expeller) Slurry Pumping Basic Training Course

Mechanics of slurry pumps Flushed seal – high flow function Sealing water pressure should be minimum 0,5-1 bar above discharge pressure ! Slurry Pumping Basic Training Course

Mechanics of slurry pumps Flushed seal – high flow function Slurry Pumping Basic Training Course

Mechanics of slurry pumps Flushed seal – low flow function Slurry Pumping Basic Training Course

Mechanics of slurry pumps Flushed seal – low flow function Slurry Pumping Basic Training Course

Mechanics of slurry pumps Dynamic seal (Expeller) – function Slurry Pumping Basic Training Course

Mechanics of slurry pumps Dynamic seal (Expeller) – function Slurry Pumping Basic Training Course

Mechanics of slurry pumps Mechanical seal – function Slurry Pumping Basic Training Course

Mechanics of slurry pumps Mechanical seal – function Slurry Pumping Basic Training Course

Performance of slurry pumps Pump curve Slurry Pumping Basic Training Course

Performance of slurry pumps Pump curve with power consumption Slurry Pumping Basic Training Course

Performance of slurry pumps Pump curves at different RPM – constant flow Slurry Pumping Basic Training Course

Performance of slurry pumps Pump curves at different RPM – constant pressure head Slurry Pumping Basic Training Course

Performance of slurry pumps System curve/Operational point with fixed pipe dimension. Fixed Pump speed. Slurry Pumping Basic Training Course

Performance of slurry pumps System curve/Operational point with different pipe dimensions. Fixed pump speed. Slurry Pumping Basic Training Course

Performance of slurry pumps System application Performance of slurry pumps System application. Variable Pipe System and Speed Slurry Pumping Basic Training Course

Performance of slurry pumps Best efficiency Pump curves at different RPM For all centrifugal pump designs, there are: ONE rpm ONE pressure head ONE volume flow At which the efficiency is Maximum. “The further we work from this area – the lower the efficiency” Slurry Pumping Basic Training Course

Performance of slurry pumps Best Efficiency Point (BEP) or Best Eff Performance of slurry pumps Best Efficiency Point (BEP) or Best Eff. Line (BEL) Wear is minimized Axial and radial shaft forces are next to nothing Electric power consumption is optimal Pump’s service life increases “If the operational point on the system curve lies within the area of the best efficiency, then we are working at the pump system’s best working point” Slurry Pumping Basic Training Course

Radial Forces = Shaft Deflection and B.E.P Slurry Pumping Basic Training Course

Total Dynamic Head (TDH) Total static head = H2-H1 Slurry Pumping Basic Training Course

Wear in slurry pumps Wear on impeller and housing (Crushing and pulverisation) Impact and sliding Impact and sliding Slurry Pumping Basic Training Course

Wear in slurry pumps General about wear Wear caused by Compression Impact (high speed) Impact (low speed) Sliding METAL POLYMER Manganese steel Rubber Protected by Ni-hard Polyurethane Chrome steel Ceramics “All machines in contact with ores or free minerals are subject to wear when movement energy, solids, and machine parts meet in the process. Slurry pumps are no exception to this!” Slurry Pumping Basic Training Course

Wear in slurry pumps Wear materials - limitations For rubber Particle size ( >5 mm) Sharp slurry (cutting damage) Hydrocarbons (diesel, pine oil, etc.) Temperature Peripheral speed pump impeller (max 27 m/s) Inlet speed For metals Acids Salts Peripheral speed pump impeller (max 45 m/s) Inlet speed Slurry Pumping Basic Training Course

Slurry pumps, supplies General “90% of all problems with slurry pumps are associated with the pump inlet (suction side)!”   Slurry Pumping Basic Training Course

Slurry pumps, supplies Pump Sump Good Not so good A good supply must … Feed slurry and not air Accept normal variations in flow Not accept sedimentation Stand free from the pump Slurry Pumping Basic Training Course

Slurry pumps, supplies Effects due to Cavitation Lost efficiency Noise and vibrations Increased wear on seals, wear parts, bearings, base etc… Mechanical damage on pump ! A pump is cavitating easier when high altitude (like Iran mine sites) The high altitude should always be calculated with, when sizing a pump and motor ! Slurry Pumping Basic Training Course

Slurry pumps, supplies Cavitation Atmospheric pressure can affect the temperature that a liquid boils at. At 2800 m.asl liquid boils at 92ºC 95ºC 1000m 100ºC Slurry Pumping Basic Training Course

Slurry pumps, supplies Cavitation If a slurry pump is to function properly, the inlet pressure must be sufficient.   If the inlet pressure drops below the vapour pressure inside the impeller (due to blockage, restrictions, etc.) vapour bubbles will be formed! Extremely high pressure waves are created when the bubbles collapse (implode). This is called cavitation and can damage the pump!! Slurry Pumping Basic Training Course