By the end of the 19th century, centrifuges had been widely used in various separation tasks. Since then, various types of centrifuges have emerged based on different application fields and separation processes. In order to provide suitable centrifuges for each application field, a large number of standards must be taken into account.
When separating materials with good filtration properties such as crystalline and coarse particulate matter, priority should be given to centrifuge machines with drum, disc centrifuge, and tube centrifuge machines, which are suitable for separating materials that are difficult to filter. The suspension contains small and soft solid particles that form a paste like, compressible precipitate.
In rotary drum centrifuges, there are mainly two types: horizontal screw settling centrifuges that separate solids and disc separators that separate liquids.
The use of solids as the separation object referred to here means that the equipment can process high solid content feed and separate relatively dry solid slag. If the separation liquid is clear and the solid residue can exist in the form of a liquid concentrate, a centrifuge that separates liquids, such as a disc centrifuge, should be selected first.
For materials with relatively high solid content, the separation requirements are often high, requiring the clear liquid to be as clear as possible and the solid-liquid residue to be as dry as possible. In this case, users need to simultaneously consider the quality of the clarified liquid and the dryness of the solid residue. Alternatively, a two-step process can be chosen, which involves first using a centrifuge for separating solids, and then using a centrifuge for separating liquids.
The Oupeng double cone centrifuge was specifically developed for this purpose, with a centrifugal area comparable to that of a disc centrifuge. This means that it can perform clarification like a disc machine, but at the same time, it can also handle materials with high solid content in the feed, and the separated solid slag is as dry as the solid slag separated by a horizontal screw settling centrifuge.
The Oupeng double cone centrifuge is a non filter drum centrifuge with a structure similar to a horizontal screw settling centrifuge. Its prominent feature is the formation of a centrifugal zone by the drum wall, in which there is a speed difference between the conveying spiral rotor and the drum, achieving the transportation of separated solids. The entire centrifuge rotor consists of a drum, a screw, and a gearbox that can generate differential speed.
Unlike the decanter centrifuge, the development of the Oupeng double cone centrifuge is aimed at separating fine and soft solids from suspensions. Separating fine solids typically requires a longer clarification zone, a stable flow rate, a larger clarification volume, and high centrifugal force within the centrifugal rotor.
The dehydration of solid sediment is accomplished by mechanical compression. Therefore, when Oupeng Machinery designed the double cone centrifuge, these requirements were taken into consideration: the drum consists of a long and gentle cone that can form a clarification area and a short and steep cone used to discharge the separated solids. The suspension is transported to the end of the long cone through the feeding tube, so the entire cone can be used as a clarification area. Liquids and solids pass through the clarification zone in the same direction (same flow principle) to avoid turbulence and backmixing phenomena. The outer shell of the drum ensures that the liquid level is as close as possible to the axis of rotation, resulting in a larger clarification volume. The maximum centrifugal separation factor allowed by high-speed rotors is 100000g. Compared to traditional horizontal settling centrifugation, the maximum separation factor is only 6000g.
Under the action of spiral propulsion, the separated solid passes through the connection of small cones. Due to the large radius of the drum here, the maximum squeezing force is received at this location. This squeezing force is increased due to a disc installed at the junction of two cone segments. The outer edge of the disc will immerse into the separated sediment. The solid forms a sealing layer between the outer diameter of the disc and the inner diameter of the drum, and accumulates due to the obstruction of the disc. Therefore, the liquid level in the clarification section of the drum moves towards the center, forming a static water pressure on the solid, which squeezes the solid out of the gap between the disc and the drum. Eventually, the solid reaches the large cone angle and is discharged from the end of the clarification area under the action of the spiral conveying device. By adjusting the adjustable impeller, the height of the liquid inside the drum can be changed, thereby altering the static pressure of the liquid acting on the solid slag. This means that during the operation of the equipment, the compactness and mud cake density of the discharged solids can be adjusted by externally adjusting the adjustable impeller.