Double Screw Pumps. Double screw pumps come in two types: sealed and unsealed. Depending on whether the medium enters the meshing space from one end or both ends, double screws are further divided into two structures: double-suction and single-suction. The double-screw pump is an external meshing screw pump, which uses two intermeshing screws that do not touch each other to pump liquid. The double-screw pump is a double-suction, non-sealed type. The driven screw extending from one end of the pump is powered by the prime mover.

Double-screw pumps come in two types: sealed and unsealed. They are further categorized into two structures based on whether the medium enters the meshing space from one end or both ends: double-suction and single-suction. The double-screw pump is an external meshing screw pump that uses two intermeshing, non-contacting screws to pump liquids. It is a double-suction, non-sealed double-screw pump. One end of the driving screw protrudes from the pump and is driven by the prime mover. The driving screw and the driven screw have threads of different pitches. The screws fit tightly with the pump housing. The driven screw is driven by the driving screw through synchronous gears.

● Advantages and Applications of Twin-Screw Pumps

Understanding the principle of twin-screw pumps, for those with external bearings, the two screws are non-contacting within the sleeve due to bearing alignment, maintaining a constant gap between the teeth (the gap value is determined by the operating conditions and the pump's specifications), and the outer circumference of the screws also maintains a constant gap with the inner circumference of the sleeve. The transmission of the two screws is accomplished by synchronized gears. The gearbox has independent lubrication, separated from the pump's working chamber. This structure greatly expands the application range of twin-screw pumps, allowing for the conveyance of not only well-lubricated media but also large quantities of non-lubricating media, media with high viscosity (up to 3*10^6 mm/s), and corrosive (acids, alkalis, etc.) or erosive liquids.

Double-screw pumps are available in two types: those with built-in bearings and those with external bearings. In the built-in bearing design, the bearings are lubricated by the conveying material. The external bearing design separates the working chamber from the bearings. Due to the pump's structure and the lateral gaps between the screws, it can handle non-lubricating media. Additionally, adjusting the synchronous gears ensures the screws do not touch, while transferring half of the output torque to the driven screw. Like all screw pumps, external bearing double-screw pumps also have self-priming capabilities. Most pumps have double-suction, symmetrically arranged conveying elements, which eliminate axial forces and offer significant lift. These characteristics make them widely used in the oilfield, chemical, and shipbuilding industries. External bearing double-screw pumps can be manufactured from different materials, such as gray cast iron and stainless steel, depending on the application. The conveying temperature can reach 250°C. The pumps come with various heating structures, with a theoretical flow rate of up to 2000 cubic meters per hour.