Slurry pump

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A slurry pump is a type of pump designed for pumping liquid containing solid particles. Slurry pumps changes in design and construction to adjust to multiple type of slurry which varies in concentration of solids, size of solid particles, shape of solid particles, and composition of solution. Slurry pump are more robust than liquid pumps; they have added sacrificial material and replaceable wear parts to withstand wear due to abrasion.

Contents

Centrifugal, positive displacement, and vortex pumps can be used for slurry. Centrifugal slurry pumps can have between bearing-supported shafts with split casing or rubber- or metal-lined casing. Configurations include horizontal, vertical suspended and submersible.

Slurry is usually classified according to the concentration of solids. Engineering classification of slurry is more complex and involves concentration, particle size, shape and weight in order to determine abrasion severity. For engineering selection of slurry pumps, slurry is classified as class 1, class 2, class 3 and class 4.

Selection of slurry pumps is more difficult than selection of pumps for water and liquids. Many factors and corrections to the duty point affect brake horsepower and wear. Root-dynamic Centrifugal Slurry Pumps (ANSI/HI 12.1-12.6-2016) provides methods for calculation of slurry pumps. The peripheral speed of the impeller is one of the main features and classification of slurry pumps. Speed must be in accordance with the slurry type classification (abrasion classification) in order to maintain a reasonable life in service due to high abrasion of solids.

Before selecting an appropriate slurry pump the engineers considers capacity, head, solids handling capacity, efficiency and power, speed and NPSH.

Slurry pumps are widely used in transport of abrasive solids in industries such as mining, dredging, and steel. They are often designed to be suitable for heavy-wearing and heavy-duty uses. Depending on the mining process, some slurries are corrosive which presents a challenge because corrosion-resistant materials like stainless steel are softer than high-iron steel. The most common metal alloy used to build slurry pumps is known as "high chrome", which is basically white iron with 25% chromium added to make it less brittle. Rubber line casings are also used for certain application where the solid particles are small.

Components

Impeller
The impeller, either elastomer, stainless steel or high-chrome material, is the main rotating component which normally has vanes to impart the centrifugal force to the liquid.
Casing
Split outer casing halves of cast contain the wear liners and provide high operation pressure capabilities. The casing shape is generally of semi-volute or concentric, efficiencies of which are less than that of the volute type.
Shaft and Bearing Assembly
A large diameter shaft with a short overhang minimizes deflection and vibration. Heavy-duty roller bearing are housed in a removable bearing cartridge.
Shaft sleeve
A hardened, heavy-duty corrosion-resistant sleeve with O-ring seals at both ends protects the shaft. A split fit allows the sleeve removed or installed quickly.
Shaft Seal
Expeller drive seal, Packing seal, Mechanical seal.
Drive Type
V-belt drive, gear reducer drive, fluid coupling drive, and frequency conversion drive devices.

Types

Submersible
Submersible slurry pumps are placed at the bottom of a tank, lagoon, pond, or another water-filled environment, and suction solids and liquids right at the pump itself. The materials are taken in at the intake and passed through a hose connected to the discharge valve. [1]
Self-Priming
A self-priming slurry pump is operated from land, and a hose is connected to the pump's intake valve. The self-priming pump draws the slurry to the pump then discharges the material from there. [2]
Flooded Suction
The flooded suction slurry pump is connected to a tank or hopper and uses gravity to move slurry and liquid from the enclosure. Located at the bottom or below the water, the pump uses the force of gravity to continuously fill the pump and then passes the material out through the discharge valve. [3]

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Submersible pump Pump designed to work submerged in fluid

A submersible pump is a device which has a hermetically sealed motor close-coupled to the pump body. The whole assembly is submerged in the fluid to be pumped. The main advantage of this type of pump is that it prevents pump cavitation, a problem associated with a high elevation difference between pump and the fluid surface. Submersible pumps push fluid to the surface as opposed to jet pumps which create a vacuum and rely upon atmospheric pressure. Submersibles use pressurised fluid from the surface to drive a hydraulic motor downhole, rather than an electric motor, and are used in heavy oil applications with heated water as the motive fluid.

Diaphragm pump

A diaphragm pump is a positive displacement pump that uses a combination of the reciprocating action of a rubber, thermoplastic or teflon diaphragm and suitable valves on either side of the diaphragm (check valve, butterfly valves, flap valves, or any other form of shut-off valves) to pump a fluid.

Impeller Rotor used to increase (or decrease in case of turbines) the pressure and flow of a fluid or gas

An impeller or impellor is a rotor used to increase the pressure and flow of a fluid. It is the opposite of a turbine, which extracts energy from, and reduces the pressure of, a flowing fluid.

A stuffing box is an assembly which is used to house a gland seal. It is used to prevent leakage of fluid, such as water or steam, between sliding or turning parts of machine elements.

Centrifugal pump

Centrifugal pumps are used to transport fluids by the conversion of rotational kinetic energy to the hydrodynamic energy of the fluid flow. The rotational energy typically comes from an engine or electric motor. They are a sub-class of dynamic axisymmetric work-absorbing turbomachinery. The fluid enters the pump impeller along or near to the rotating axis and is accelerated by the impeller, flowing radially outward into a diffuser or volute chamber (casing), from which it exits.

Liquid-ring pump A rotating positive-displacement pump.

A liquid-ring pump is a rotating positive-displacement pump.

Circulator pump pump for circulating fluid around a closed circuit for hydronic purposes

A circulator pump or circulating pump is a specific type of pump used to circulate gases, liquids, or slurries in a closed circuit. They are commonly found circulating water in a hydronic heating or cooling system. Because they only circulate liquid within a closed circuit, they only need to overcome the friction of a piping system.

Lobe pump

A lobe pump, or rotary lobe pump, is a type of positive displacement pump. It is similar to a gear pump except the lobes are designed to almost meet, rather than touch and turn each other. An early example of a lobe pump is the Roots Blower, patented in 1860. to blow combustion air to melt iron in blast furnaces, but now more commonly used as an engine supercharger.

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Plunger pump

A plunger pump is a type of positive displacement pump where the high-pressure seal is stationary and a smooth cylindrical plunger slides through the seal. This makes them different from piston pumps and allows them to be used at higher pressures. This type of pump is often used to transfer municipal and industrial sewage.

A rotodynamic pump is a kinetic machine in which energy is continuously imparted to the pumped fluid by means of a rotating impeller, propeller, or rotor, in contrast to a positive displacement pump in which a fluid is moved by trapping a fixed amount of fluid and forcing the trapped volume into the pump's discharge. Examples of rotodynamic pumps include adding kinetic energy to a fluid such as by using a centrifugal pump to increase fluid velocity or pressure.

Volute (pump) curved funnel that increases in area as it approaches the discharge port; casing in a centrifugal pump that receives the fluid being pumped by the impeller, maintaining the velocity of the fluid through to the diffuser

A volute is a curved funnel that increases in area as it approaches the discharge port. The volute of a centrifugal pump is the casing that receives the fluid being pumped by the impeller, maintaining the velocity of the fluid through to the diffuser. As liquid exits the impeller it has high kinetic energy and the volute directs this flow through to the discharge. As the fluid travels along the volute it is joined by more and more fluid exiting the impeller but, as the cross sectional area of the volute increases, the velocity is maintained if the pump is running close to the design point. If the pump has a low flow rate then the velocity will decrease across the volute leading to a pressure rise causing a cross thrust across the impeller that we see as vibration. If the pump flow is higher than design the velocity will increase across the volute and the pressure will decrease according to the first law of thermodynamics. This will cause a side thrust in the opposite direction to that caused by low flow but the result is the same - vibration with resultant short bearing and seal life.

Chopper pumps

A chopper pump is a centrifugal pump which is equipped with a cutting system to facilitate chopping or maceration of solids that are present in the pumped liquid. The main advantage of this type of pump is that it prevents clogging of the pump itself and of the adjacent piping, as all the solids and stringy materials are macerated by the chopping system. Chopper pumps exist in various configurations, including submersible and dry-installed design and they are typically equipped with an electric motor to run the impeller and to provide torque for the chopping system. Due to its high solids handling capabilities, the chopper pump is often used for pumping sewage, sludge, manure slurries, and other liquids that contain large or tough solids.

High-density solids pumps are hydrostatically operating machines which displace the medium being pumped and thus create a flow.

Flexible impeller positive-displacement pump

A flexible impeller pump is a positive-displacement pump that, by deforming impeller vanes, draws the liquid into the pump housing and moves it to the discharge port with a constant flow rate. The flexibility of the vanes enables a tight seal to the internal housing, making the pump self-priming, while also permitting bi-directional operation. The output from these pumps tends to be smooth or gentle when compared to the operation of a reciprocating pump. In 1938, Arthur M. Briggs filed a patent for this type of pump.

References

  1. "Submersible Slurry Pumps | Sand, Sludge, & Others Solids". DAE Pumps. Retrieved 2020-09-25.
  2. "Self-Priming Pumps". DAE Pumps. Retrieved 2020-09-25.
  3. "Slurry Pumps". DAE Pumps. Retrieved 2020-09-25.