Slurry pump design considerations

Posted by uuuseff on November 19th, 2019

Slurry Pump Hydraulic Design and Structural Design Considerations a. Wear and Hydraulic Problems: In order to reduce wear and tear, the flow rate of rotating parts and fluids should be kept low enough to increase the section thickness of the pump carbide liner or elastomeric lubricant , To meet the needs of the actual operation. The radial profile of the impeller is generally close to a rectangle with a frontal seal on the vertical to reduce the axial area of ​​rotation. The pump casing is typically designed as a semi-helical or annular shape that maintains less wear over a wide range of points near the highest efficiency point the amount. When the need to transport large particles of solid, built-in closed impeller width is usually larger, the number of blades is reduced to 2-3 pieces, to improve pump wear under the premise of the pump hydraulic performance will be reduced to varying degrees. In order to minimize pump wear at different operating conditions with the highest efficiency flow rate, the volute structure of the slurry pump ranges from a helical volute to a semi-helical volute to a toroidal volute and OB-type structure. The type of impeller is an RV type with a rectangular cross section in a radial direction, an ME type with a twisted and radially rounded rectangular cross section, and the most common HE type. Different combinations of impellers and volutes have different hydraulic and wear characteristics. Generally have: 1. HE / T combination, with good hydraulic properties, but poor wear performance; 2. ME / C combination, with good hydraulic properties and wear properties; 3. A or OB-type volute and impeller of the different combinations can be used to wear more serious occasions. b. Material Problems: Slurry pump impeller and volute materials, such as rubber, neoprene, polyurethane resin and other elastic materials, generally used for impeller exit speed of less than 23m / s occasions, it can increase the pump effective steam Erosion margin. c. Mechanical Design (Shafts, Bearings, Seals, Pumps, etc.) Shafts and bearings must have higher strength and rigidity and reliability. Trapezoidal screwed impellers are generally capable of withstanding heavy loads, using sliding thrust bearings under heavy loads, and ball bearings are generally used at light loads. The slurry pump has no radial seal, so allowing the shaft to skew more than a regular pump would limit the life of stuffing boxes and mechanical seals. Therefore, the general use of shorter axis, the allowable skew is also smaller, can increase the life of stuffing box. In general, high-pressure water should be injected into the sealed cavity to dilute the material to prolong the service life of the pump. If the material can not be diluted, a push-type seal can be used and generally used in a single-stage slurry pump, but the efficiency will be 3% reduce. The mechanical seal is normally partially balanced and can be cooled by the transport fluid at this time. In some cases, the pump may idly rotate and a double mechanical seal must be used. In light load conditions, the use of general mechanical seal; under heavy load conditions, you must use a special mechanical seal structure. Generally, pump casing made of elastic material may be too small in strength to withstand large pressure loads. Therefore, a pump casing should be added and called double-walled structure. The materials are generally made of hard metal, rubber or polyurethane resin. For large pumps, taking into account the size and cost constraints, can be used bolt fastening structure. d. The effect of solid particles on the centrifugal pump The flow-head curve of the slurry pump changes more smoothly. However, the flow resistance loss of the transmission pipe slowly increases with the increase of the flow rate. The angle between the pipe characteristic curve and the performance curve is small , Making a small change in head will cause a significant change in traffic. Slurry pump wear is generally very serious, parts life is sometimes only one month. So using the right material is a key factor in pump design. The main reason for wear is sliding erosion and particle impact.

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