What Is a Shell Pump?

Rotary shell pump, also known as rotary jet pump, pitot tube pump, is a new type of small flow high pressure pump with unique structure and working principle, belonging to a very low specific speed pump. China's rubber industry introduced two rotary shell pumps from the United States for the first time ten years ago for the transportation of raw material oil in a carbon black production line, which is significantly superior to other types of pumps in terms of smooth operation and service life. At present, this kind of pump is rarely used in other industries, the main reason is that manufacturers and users know little about the characteristics and structure of the pump. The main features of rotary shell pumps are: (1) Suitable for small flow and high head conveyance, the general flow is within tens of square meters per hour, the small is only a few square meters, the head is hundreds of meters, and some are up to kilometers; (2) Simple structure, small size, so small maintenance, low maintenance cost, long service life; (3) Strong sealing reliability, only mechanical seal at the low-pressure inlet of the rotary pump, no sealing problem at the main shaft end It solves the high-pressure sealing problem that is common in high-pressure pumps; (4) The flow characteristic curve is smooth and the liquid output has no pulsation, which is very suitable for production posts that require smooth fluid transportation; (5) The efficiency is relatively high, and for extremely low specific speed The number of centrifugal pumps is very low because the friction loss of the impeller and the disc is significantly increased, while the rotary pump has no disc friction loss and no volute hydraulic loss. The efficiency is still higher than the centrifugal pump with the same number of revolutions.

Rotary Shell Pump

Due to its outstanding advantages, rotary shell pumps can be used in many industries to replace small-flow high-lift centrifugal pumps, multi-stage centrifugal pumps, high-pressure gear pumps, and screw pumps. In China, it is rarely used and there is much room for promotion and application.
Since the rotary shell pump meets the requirements of high pressure heads and no leakage, it has broad application prospects in rubber, petroleum, chemical, metallurgy, food, paper, printing and dyeing industries. For example: The rotary shell pump has the advantage of the full range of the lift curve, making it the first choice for high-pressure pumps in the central cleaning system of the food industry; because the mechanical seal of the rotary shell pump is at the low pressure of the pump, the seal is reliable, making it applicable to the petrochemical industry In light hydrocarbon processing and some high-pressure chemical processes; in the thermal power plant, the rotary shell pump is used as the boiler feed pump and cooling pump, and the steam turbine is used as the high pressure pump to control the fuel and NOX injection at the same time; in the paper industry, The high-pressure water flow generated by the shell pump cleans the covering on the machine to produce high-quality paper.

Rotary casing pump is composed of rotor, pitot tube, bearing block parts, outer casing and inlet and outlet pipe, as shown in the figure

The liquid enters the impeller 4 from the liquid inlet pipe 1 and obtains kinetic energy due to the high-speed rotation of the impeller. The liquid enters the periphery of the drum 6 in the axial direction from the periphery of the impeller. As the cross-section of the pitot tube gradually expands, the liquid flow velocity gradually decreases, thereby converting the kinetic energy of the liquid into pressure energy. Finally, the high-pressure liquid is discharged from the liquid discharge pipe 3. Because the impeller 4 and the rotating drum 6 are integrated and synchronized to rotate, the friction of the house disc is lost during the process of obtaining kinetic energy of the liquid. This is the origin of the much higher efficiency of rotary shell pumps and high-speed pumps and multi-stage centrifugal pumps with the same ultra-low specific speed. Pitot tube internal flow channel design, dimensional accuracy and finish are the key factors that determine the efficiency of kinetic energy conversion to pressure energy. ^[1]