Duwan Environmental G-type Screw Pump Technical Description:

Screw pumps are a type of positive displacement pump, which transfer fluids through the volumetric change of several intermeshing screws. Depending on the number of intermeshing screws working simultaneously, screw pumps are typically categorized into single-screw pumps and multi-screw pumps (including twin-screw, triple-screw, quintuple-screw, etc.).

Single Screw Pump

A single screw pump is a pump that operates based on the reciprocating internal meshing volume principle, primarily composed of an eccentric rotor and a fixed sleeve stator.The impeller and stator both possess unique geometric shapes, forming multiple sealed working chambers within the pump. As the impeller rotates, these sealed chambers continuously form at one end and disappear at the other. Each sealed chamber can smoothly and pulsation-free draw in liquid at one end and discharge it at the other. In a single screw pump, the liquid flows uniformly along the axial direction, with a low internal velocity. Due to the constant volume,涡流 and turbulence are not formed, resulting in no pressure loss for the liquid being transported. The typical structure of a single screw pump is illustrated as follows.Figure 1.

Image1. Single Screw Pump Structural Diagram

1—Discharge port; 2—Stator; 3—Screw shaft; 4—Universal joint assembly; 5—Inlet; 6—Connecting shaft; 7—Stuffing box; 8—Stuffing cover; 9—Bearing housing; 10—Bearing cap; 11—Motor; 12—Coupling; 13—Shaft sleeve; 14—Bearing; 15—Drive shaft; 16—Base

Single screw pumps, due to their unique structure and operational characteristics, offer numerous advantages over piston pumps, centrifugal pumps, vane pumps, and gear pumps:Can transport media with high solid content; flow is uniform and pressure is stable, more so at low speeds; flow is proportional to the pump's speed, thus offering good variable adjustment capabilities; commonly used for transporting media of different viscosities; the pump can be installed at any angle, featuring small size, light weight, low noise, simple structure, and easy maintenance.

Single screw pumps are currently widely used in oil drilling and transportation.

2. Multi-screw pump

Multi-screw pumps include twin-screw pumps, triple-screw pumps, and five-screw pumps, with twin-screw and triple-screw pumps being the most common.This pump features one active screw, which is a right-hand threaded convex screw, while the rest are driven screws, which are left-hand threaded concave screws.。

1) Twin-screw pump

Double-screw pumps are external meshing screw pumps that use two intermeshing screws, which do not touch each other, to pump liquids. One screw is the driving screw, and the other is the driven screw. The structure and working principle are illustrated as follows.Figure 2 illustrates that in a double-screw pump, as a positive displacement pump, the suction chamber should be tightly isolated from the discharge chamber. As the screws rotate, the volume of the suction chamber increases, causing a decrease in pressure, and the liquid enters the suction chamber due to the pressure difference between the pump's inside and outside. With the rotation of the screws, the liquid in the sealed chamber moves continuously and uniformly along the axial direction to the discharge chamber. Since the volume at one end of the discharge chamber gradually diminishes, the liquid is expelled.

ImageStructure and Working Principle of Twin-Screw Pumps

1—Gearbox Cover; 2—Rack; 3—Rolling Bearing; 4—Rear Support; 5—Mechanical Seal; 6—Nut A, B; 7—Pump Body; 8—Adjustment Bolt; 9—Sleeve; 10—Driven shaft; 11—Front Bracket; 12—Driven shaft; 13—Rolling Bearing; 14—Pressure Cover

For external bearing double-screw pumps, the two screws are not in contact with each other 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 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 synchronous gears. The gearbox features independent lubrication, separated from the pump working chamber. This structure significantly expands the application range of double-screw pumps, enabling them to transport not only lubricious media but also large quantities of non-lubricious media, across various viscosities (up to high viscosity).Materials with a flow rate of 3x 106mm2/s, as well as corrosive (acids, alkalis, etc.) and erosive liquids.Double-screw pumps, due to the presence of a constant gap and characteristics on the profile, are classified as non-sealed positive displacement pumps. Therefore, in addition to transporting pure liquids, they can also handle mixtures of gases and liquids, i.e., gas-liquid mixing transport.This is also one of the very unique advantages of twin-screw pumps.

Screw pumps can self-prime due to their unique design, eliminating the need for a dedicated self-priming unit. Moreover, with a lower axial flow velocity of the impeller shaft, they possess strong suction capabilities, meaning even minimal quantities can be effectively lifted.NPSHr value.The twin-screw pump can also be run dry.Due to the non-contacting movement parts during operation, brief dry runs won't damage the pump components, which offers significant convenience for automated control processes. However, the duration of dry operation is limited by various factors and is generally quite short.

2) Tri-screw pump

The internal structure of the three-screw pump consists of a driving screw, two driven screws, and a sleeve enclosing the three screws, forming a sealed cavity. The liquid inside the cavity moves axially as the screws rotate, achieving the purpose of conveying the liquid. The special structure of this pump ensures that the main and driven shafts are not subjected to radial forces. The axial force is balanced hydraulically, with the bearings only bearing the weight of the screws and a minimal residual axial force. The driven shaft is inserted into a balancing sleeve (which serves to balance the axial force and also acts as a sliding bearing), and the geometric dimensions of the screws ensure that no torque is transferred from the main to the driven shaft. The driven shaft rotates due to the pressure of the conveyed liquid, thereby ensuringThe three-screw design boasts a long service life and high mechanical efficiency, with an excellent linear design and processing technique that completely isolates each sealing chamber, thereby ensuring a high volumetric efficiency.。

Three-screw pumps are commonly used as auxiliary pumps in oil depots and pumping stations for transferring lubricating oils and oils of medium viscosity. Double-suction horizontal three-screw pumps for oil-gas mixing transportation are widely used in oil and gas collection and transportation in various oil fields. The structure of the three-screw pump is as shown in the figure.Figure 3.

Image3-Double Suction Triple Screw Pump Structure Diagram

1—Actuator Screw; 2, 7—Driven Screw; 3—Sleeve; 4—Pump Body; 5—Stuffing Box; 6—Bearing

Jiangsu Du'an Environmental ProtectionG TypeScrew PumpProduct Description:

Du'an Environmental ProtectionG-type screw pumpThe core component is the external thread"The 'rotor' and the internal threaded 'stator' form an isolated, continuous sealed space known as the 'sealing chamber' when the rotor is inserted into the stator. As the rotor rotates within the stator, it generates a powerful suction to draw in high-viscosity liquids, continuously creating new sealing chambers to move the liquid towards the discharge side. The liquid inside the suction sealing chamber is continuously transported forward within the sealed space."

The cross-sectional area of the sealed chamber is independent of the rotor's position, remaining fixed at any given moment. The amount discharged is also consistent, thus the discharge volume per unit time is directly proportional to the rotor's rotational speed. Furthermore, simply changing the direction of the rotor's rotation will reverse the directions of intake and discharge.

Screw pumpAdvantages:

Wide application range, capable of conveying all types of liquid and even non-liquid materials, availableContinuous low pulsation conveying medium is not agitated during pumping, unaffected by compression and shearing. The conveying volume is proportional to the speed, allowing variable frequency adjustment of the conveying volume, with high-precision measurement and high conveying efficiency.，All liquids can be pumped with minimal agitation and pulsation.，Easy to maintain and inspect。

Duwan Environmental ProtectionType G screw pump, traffic can reach 400 m³/h output pressure up to 7.2 Mpa

Overcurrent metal components can be made from various materials, ranging from tool steel to nickel.Chrome steel, high corrosion-resistant materials such as duplex stainless steel, Hastelloy, and titanium alloysRegular materials are categorized as:304 stainless steel, 316 stainless steel. The motors are categorized into AC speed control, electromagnetic speed control, variable frequency speed control, standard motors, and explosion-proof motors, etc.

Screw Pump Sealing DeviceUtilizing various stator rubber materials, ranging from wear-resistant natural rubberNBR,三元乙丙橡胶(EPDM),氯磺化橡胶(CSM),四氟(PTFE),氟橡胶(FPM),氢化丁腈橡胶(HNBR)

Filling seal or mechanical seal; other sealing types are also available for selection.

Du'an Environmental ProtectionG-type screw pump executionStringent quality standards and testing proceduresGuarantee the product is intact and of superior performance before shipment.