Section 1: Overview of Rotating Shell Pump

Rotary Shell Pump, also known as a rotary jet pump or Pitot pump, is a novel low-flow, high-pressure pump with a unique structure and working principle, categorized under low NPSH pumps. Ten years ago, our country's rubber industry first imported two rotary shell pumps from the United States for the conveyance of raw oil in carbon black production lines, which significantly outperform other types of pumps in terms of stable operation and service life. Currently, this pump is rarely used in other industries, primarily due to limited understanding of its characteristics and structural principles among manufacturers and users.

Section II: Features of the Centrifugal Pump

Key features of the radial pump include:

(1) Suitable for low flow and high head transfer, typically with flow rates of a few tens of cubic meters per hour, some as low as a few cubic meters, and head heights ranging from hundreds to over a thousand meters.

(2) Simple structure, compact size, resulting in minimal maintenance and low repair costs, with a long service life.

(3) Strong sealing reliability, with only mechanical sealing at the low-pressure inlet of the screw pump housing, no sealing issues at the main shaft end, solving the common high-pressure sealing problem in high-pressure pumps.

(4) Flow characteristic curve is smooth, and the liquid output is pulseless, making it highly suitable for production positions with stable fluid transportation requirements.

(5) Higher efficiency relative to low NPSH centrifugal pumps, which have significantly higher blade disk friction losses. Suction volute pumps, on the other hand, do not experience disk friction losses nor volute hydraulic losses. Although there are hydraulic losses in the rotor chamber and collector pipe, their efficiency is still higher than that of centrifugal pumps with the same NPSH.

Section 3: Rotating Shell Pump Application Prospects

Rotary Vane Pumps, due to their outstanding advantages, can replace small flow high head centrifugal pumps, multi-stage centrifugal pumps, high-pressure gear pumps, and screw pumps in numerous industries with extensive applications. However, in our country, their use is still rare, presenting a significant potential for widespread promotion and application.

Due to the旋壳泵's ability to meet high head and zero leakage requirements, it has broad application prospects in industries such as rubber, petroleum, chemicals, metallurgy, food, papermaking, and dyeing. For instance, the旋壳泵's full-range working advantage of the head curve makes it an ideal choice for high-pressure pumps in the food industry's central cleaning systems; its mechanical seal at the low-pressure pump section ensures reliable sealing, allowing its use in petrochemical industry light hydrocarbon processing and some high-pressure chemical processes; in power plants, the旋壳泵 is used as a boiler feed and cooling water pump, and as a high-pressure pump for steam turbines to control fuel and NOX injection simultaneously; in the paper industry, high-pressure water streams generated by the旋壳泵 are used to clean machinery surfaces, producing high-quality paper.

Section 4: Centrifugal Pump Structure

The rotary shell pump consists of components such as the rotor, pitot tube, bearing housing, housing, and in/out fluid pipes. The bearing housing component 8 is the same as that of a common centrifugal pump, with the flow component impeller 4 and drum (equivalent to the pump housing of a centrifugal pump) 6 integrated as one unit, bolted to the main shaft 7 to form the rotor assembly. The outer periphery of the drum 6 is protected by the housing 9, which is bolted to the bearing housing 8. The right end cover of the housing 9 is fixed with a mechanical seal 2, an in-fluid pipe 1, and an out-fluid pipe 3. The core component, the pitot tube 5, is fixed on the out-fluid pipe 3, extending from the axis to near the inner wall of the drum 6.

Liquid enters the impeller 4 through inlet pipe 1, gaining kinetic energy due to the high-speed rotation. The liquid then enters the outer periphery of drum 6 along the axial direction, with the high-speed liquid entering the entrance of the pitot tube 5 located between the drum and the outer periphery. As the cross-sectional area of the pitot tube gradually expands, the liquid flow rate decreases, thereby converting the kinetic energy of the liquid into pressure energy. The high-pressure liquid is then discharged through outlet pipe 3. Since the impeller 4 and drum 6 are integrated and rotate synchronously, there is no disk friction loss during the liquid's acquisition of kinetic energy. This is the reason why the helical case pump is much more efficient than the same ultra-low specific speed high-speed pump and multi-stage centrifugal pump. The design of the pitot tube flow channel and the precision and smoothness of its dimensions are key factors determining the efficiency of kinetic energy conversion into pressure energy.