The use of high viscosity gear pump features

Gear pumps are ideal for conveying highly viscous liquids and have a wide range of applications. The majority of high-viscosity gear pumps used in the petroleum and chemical industries in China still rely on imports.

At present, although domestic enterprises have produced many gear pumps suitable for conveying high-viscosity liquids, due to imperfect testing methods, there are still some problems in material selection, leakage and noise prevention. In particular, domestic high-viscosity gear pumps are inefficient. There is a big gap between the reliability, service life, and foreign products. Therefore, most of the high-viscosity gear pumps used in the petroleum and chemical industries in China still rely on imports.

The development characteristics of high-viscosity gear pumps at home and abroad are as follows:

Gear structure: The gears of high-viscosity gear pumps are commonly known as straight teeth, helical teeth, herringbone teeth, and helical teeth. The tooth profiles mainly include involute and arc patterns. Usually, small gear pumps use involute spur gears. Gear pumps often use shift gears. Melt pumps that deliver high-viscosity, high-pressure polymer melts use involute helical gears. Gears and shafts are integrated. Their rigidity and reliability are higher than those of gears and shafts. Pumps. The gears of foreign low-pressure gear pumps often use a square structure, that is, the tooth width of the gear is equal to the diameter of the tip circle. The tooth width of the high-viscosity gear pump used in high-pressure applications is smaller than the diameter of the tip circle, which is to reduce the gear. The radial compression area reduces the load on gears and bearings.

Pump body and heating method: In general, the heavier the pump casing of the gear pump, the higher the temperature and compressive strength. The pump body material is usually ductile iron, and can also be cast from a cast aluminum alloy die, or Extrusion of aluminum alloy processing and manufacturing. When the transmission medium is corrosive, you can use higher cost stainless steel materials. Foreign high-viscosity gear pumps use alloy steel with high nickel and chromium content as pump casing material. The comprehensive performance of the material in terms of strength, reliability and cost is better. In order to solve the phenomenon of trapped oil in the gear pump, a symmetrical unloading groove is usually opened on the pump cover, or an asymmetric unloading groove is opened in the direction of the low pressure side. The side adopts a conical unloading tank and the discharge side is a rectangular unloading tank. The depth of the unloading tank is also deeper than the gear pump used in the hydraulic industry.

Due to the high viscosity of the medium delivered by the high viscosity gear pump, in order to reduce the flow resistance and improve the pump's liquid absorption capacity, the medium must be heated or insulated. Usually the heating of the heating element can make the viscous liquid heated evenly. If the temperature does not fluctuate, When large, highly viscous liquids are prone to degradation, fluid heating is recommended, especially for gear pumps with large displacements. The fluid heating is divided into built-in and external configurations. The so-called built-in type refers to the gear pump body or end cap. The internal design of the hot sleeve, the external type is to connect the hot sleeve and the pump body together through bolts. To steam, thermal oil, or cooling water in the jacket, according to the specific conditions of the media. Built-in application In the case of high temperature uniformity of the delivery liquid, or require uniform cooling of the high-temperature liquid. When the electric heating method lacks safety or the temperature control requirements are not high, an external-type internal gear pump can be used. The jacket of the pump head section can control the temperature of the fluid being transported, and can be equipped with an external jacket in both high and low temperature environments.