Pumps designed for pumping slurries will be heavier duty than those designed for less viscous liquids since slurries are heavy and difficult to pump.
Slurry pumps are typically larger in size than standard pumps, with more horsepower, and built with more rugged bearings and shafts. The most common type of slurry pump is the centrifugal pump. These pumps use a rotating impeller to move the slurry, similar to how a water-like liquid would move through a standard centrifugal pump.
Centrifugal pumps optimized for slurry pumping will generally feature the following in comparison to standard centrifugal pumps: Larger impellers made with more material. This is to compensate for wear caused by abrasive slurries. Fewer, thicker vanes on the impeller. This allows the passage of solids more readily typically 2-5 vanes, compared to 5-9 vanes on a standard centrifugal pump.
For pumping abrasive slurries, these types of pumps may also be made from specialized high wear alloys such as AL-6XN® or Hastelloy® C-22®. Hardening stainless steel is also a common option for abrasive slurries, with Expanite and Armoly being two hardening processes.
For certain types of slurry pumping conditions, positive displacement pumps may be a more appropriate choice than a centrifugal-style pump. These conditions include: A low slurry flow rate, A high head (i.e., the height to which the pump can move liquid), A desire for greater efficiency than that afforded by centrifugal pumps, Improved flow control.
Common types of positive displacement pumps used in slurry pumping applications include: Rotary Lobe pumps - These pumps use two meshing lobes rotating within a pump's housing to move fluids from the pump's inlet to its outlet. Twin-screw pumps - These pumps employ rotating screws to move liquids and solids from one end of the pump to another. The screws' turning action creates a spinning motion that pumps material. Diaphragm pumps - These pumps use a flexible membrane that expands the volume of the pumping chamber, bringing in fluid from an inlet valve and then discharging it through an outlet valve.
In determining which type of slurry pump is best suited for your particular application, follow these four simple steps.
A slurry pump is a device used to pressurize or convey liquids such as water, oil, acid, alkali, emulsion, suspoemulsion, liquid metal, as well as liquids, gas mixes, and liquids containing suspended solids. They are heavy duty and robust pumps. Mining, dredging, steel processing, foundries, electricity generation, drilling mud, pulp and paper, wastewater treatment, mineral processing, etc. are a few examples of industries that manage slurries. Slurry movement requires more force than movement of ordinary fluids because of the solid particles present and the fact that they are extremely thick and viscous. As a result, heavy-duty pumps with specialized designs are needed to function as slurry pumps.
Following are some crucial factors that must be taken into account when choosing the precise slurry pumps: Including the size and kind of the present solid particles, the type of slurry that needs to be managed. The primary factor in choosing the pump material for the job is the slurrys corrosive quality. Pipe size: the pipe ID needs to be far larger than the largest permitted particle size. Prerequisites for static heads, available NPSH, cost, length of the pipeline or slurry pipe. The lower the discharge pressure and speed, in particular, the better for pump operating parameters.
Slurries are handled by two different kinds of pumps :-
A positive displacement slurry pump is better suited when a low slurry flow rate with superior flow control and more efficiency is sought. For slurry operations, typical positive displacement pumps include screw pumps, Rotary-lobe pumps, diaphragm pump, Progressive cavity pumps, gear pumps, peristaltic pump.
The centrifugal pump, which has a larger impeller, thicker vanes, and higher horsepower, is the most popular kind of slurry pump. The centrifugal slurry pump operates in a very straightforward manner. They push the slurry into the discharge using the centrifugal force produced by a rotating impeller. The following decisions should be made while selecting a centrifugal slurry pump: A recessed type large and thick open impeller can be used to reduce impeller wear. Avoid using closed impellers. Rubber lining and a metal case of the suitable thickness should be taken into account. Cavitation problems.
The term horizontal slurry pumprefers to a pump whose shaft is parallel to the horizontal plane. With high-strength and wear-resistant materials for the over-flow sections, the horizontal slurry pump is a single-stage, single-suction, axial suction cantilever horizontal centrifugal pump. Standard electrical motors and seals are frequently used in horizontal slurry pumps. Plants in areas at risk of floods should not use them.
A vertical slurry pump is one in which the pump shaft is positioned perpendicular to the horizontal plane. The term submerged slurry pump refers to the fact that the pump head should be submerged beneath the liquid. Vertical slurry pumps are not entirely submerged underwater, though.
The pump and the motor are coaxially integrated to form a submersible slurry pump, and the motor is submerged in the slurry. There is no need to erect elaborate fixtures and safety precautions on the ground. A mechanical seal around the motor serves as protection, successfully preventing high-pressure water and other pollutants from penetrating the motor cavity. The slurry concentration is controlled by the diving depth, and the slurry automatically pours into the pump to conserve energy. The stirring impeller makes direct contact with the deposition surface.
The impeller of the submerged slurry pump is a semi-open impeller, and it is a vertical single-stage single-suction cantilever pump. At the impeller’s suction edge extension, a mixing blade is placed.
Four criteria should be taken into consideration while choosing the right kind of slurry pump: performance, material being transported, sealing type, and transmission mode. However, it may also be influenced by other elements, such as the slurry‘s acidity or alkalinity and the working circumstances on the job site.
Centrifugal Pumps for Slurry
Slurry is one of the most challenging fluids to move. It's highly abrasive, thick, sometimes corrosive, and contains a high concentration of solids. No doubt about it, slurry is tough on pumps. But selecting the right centrifugal pump for these abrasive applications can make all the difference in the long-term performance.
Slurry is any mixture of fluid and fine solid particles. Examples of slurries would include: manure, cement, starch, or coal suspended in water. Slurries are used as a convenient way to handle solids in mining, steel processing, foundries, power generation, and most recently, the Frac Sand mining industry.
Slurries generally behave the same way as thick, viscous fluids, flowing under gravity, but also pumped as needed. Slurries are divided into two general categories: non-settling or settling. Non-settling slurries consist of very fine particles, which give the illusion of increased apparent viscosity. These slurries usually have low wearing properties, but do require very careful consideration when selecting the right pump because they do not behave in the same manner as a normal liquid does. Settling slurries are formed by coarse particles that tend to form an unstable mixture. Particular attention should be given to flow and power calculations when selecting a pump. The majority of slurry applications are made up of coarse particles and because of this, have higher wear properties. Below are common characteristics of slurries: Abrasive, Thick consistency, Can contain a high amount of solids, Usually settle quickly, Require more power to operate than a water pump.
Many types of pumps are used for pumping slurries, but the most common slurry pump is the centrifugal pump. The centrifugal slurry pump uses the centrifugal force generated by a rotating impeller to impact kinetic energy to the slurry, similar to how a water-like liquid would move through a standard centrifugal pump. Slurry applications greatly reduce the expected wear life of pumping components. Its critical that pumps designed for these heavy-duty applications are selected from the start. Consider the following when making selections:
To ensure the pump will hold up against abrasive wear, the impeller size/design, material of construction, and discharge configurations must be properly selected. Open impellers are the most common on slurry pumps because theyre the least likely to clog. Closed impellers on the other hand are the most likely to clog and the most difficult to clean if they clog. Slurry impellers are large and thick. This helps them operate longer in harsh slurry mixtures.
Slurry pumps are generally larger in size when compared to low-viscosity liquid pumps and usually require more horsepower to operate because they're less efficient. Bearings and shafts must be more rugged and rigid as well. To protect the pump's casing from abrasion, slurry pumps are oftentimes lined with metal or rubber. Goulds Pumps, for example, lines their XHD (Extra Heavy Duty) slurry pump with rubber. Metal casings are composed of hard alloys. These casings are built to withstand the erosion caused by increased pressure and circulation. The casings are selected to suit the needs of the application. For instance, pumps used in cement production handle fine particles at low pressures. Therefore, a light construction casing is acceptable. If the pump is handling rocks, the pump casing and impeller will need a thicker and stronger casing.
Those with experience pumping slurries know it's not an easy task. Slurries are heavy and difficult to pump. They cause excessive wear on pumps, their components, and are known to clog suction and discharge lines if not moving fast enough. It's a challenge to make slurry centrifugal pumps last for a reasonable amount of time. But, there are a few things you can do to extend the life of your slurry pump and make pumping slurry less of a challenge. Find the sweet spot that allows the pump to run as slow as possible (to reduce wear), but fast enough to keep solids from settling and clogging the lines. To reduce wear, lower the pump's discharge pressure to the lowest point possible. Follow proper piping principles to ensure a constant and uniform delivery of the slurry to the pump. Pumping slurries poses several challenges and problems, but with proper engineering and equipment selection, you can experience many years of worry-free operation. It's important to work with a qualified engineer when selecting a slurry pump because slurries can wreak havoc on a pump if not properly selected.
