A three-phase horizontal screw centrifuge mainly consists of a drive unit, differential gear, screw conveyor (screw propeller), drum, feed pipe, casing, base, and control system. It has a compact structure and can achieve continuous automatic separation.
The drum system typically consists of a straight drum section, a conical drum section, a large end cover, and a small end cover, mostly made of duplex stainless steel. The inner wall of the drum can be designed with longitudinal grooves to improve the efficiency of solid phase conveying. The conical drum section has a 360° open circular discharge port and is equipped with a replaceable carbide wear-resistant sleeve.
The screw conveyor (screw propeller) is located in the center of the drum and is made of duplex stainless steel. The working surface of the screw blades can be overlaid or inlaid with carbide blocks to improve wear resistance. The screw has a distribution chamber inside, connected to the feed pipe, for uniform material distribution. A baffle may be installed on the outer wall of the screw near the conical section to prevent the lighter phase from entering the discharge port.
The differential gear connects the drum and the screw, achieving differential speed between them, which is crucial for continuous discharge. Common types include planetary gear differentials (high torque capacity, stable and reliable) and cycloidal gear differentials (reliable performance, low operating temperature).
The drive and control system typically employs a dual-motor drive: the main motor drives the drum, and the auxiliary motor drives the screw via a differential. Both the main and auxiliary motors are controlled by frequency converters, allowing for stepless adjustment of the differential speed. Some models use a DC common bus power supply, enabling energy feedback when the auxiliary motor is generating electricity.
In the feeding and discharging system, the feed pipe introduces the material into the distribution chamber inside the screw. The separated heavy phase liquid is discharged via a centrifugal pump, used to adjust the position of the neutral layer of the heavy and light phases and control the discharge layer. The light phase liquid and solid phase (slag) are discharged separately through different outlets on the large end cover and the slag discharge port at the conical end. Some models have adjustable baffles at the oil and water outlets.
The machine casing is a fully enclosed stainless steel enclosure used to collect and guide the separated liquid and solid phases. The base is usually welded from high-quality carbon structural steel to support the entire machine, and is equipped with vibration dampers at the bottom.
