Horizontal spiral settling centrifuge

1. Overview

The horizontal spiral settling centrifuge (referred to as the horizontal spiral centrifuge) is a device that uses the principle of centrifugal settling to separate solid particles from suspensions. It can clarify, dehydrate, or grade suspensions with solid particle sizes ranging from 0.002-3mm, concentrations ranging from 0.5% to 40%, and solid-liquid phase density differences greater than 0.06g/cm3.

2. Process principle

The horizontal spiral settling centrifuge is driven by a motor to rotate a non porous drum and a concentric feeding screw in the same direction at a certain differential speed. The material is continuously introduced into the conveying spiral inner cylinder through the feeding pipe, accelerated and enters the rotary drum. Under the action of centrifugal force, heavier solid substances deposit on the drum wall to form a sediment layer. The feeding spiral continuously pushes the deposited solid matter to the cone end of the drum, and discharges it out of the drum and outside the machine through the slag discharge port. The lighter liquid phase forms an inner liquid ring, which continuously overflows from the large end overflow port of the drum and is discharged outside the machine through the discharge port.

3. Product Features and Applications

The YZ-WL series centrifuge is a horizontal spiral discharge, continuous operation settling centrifuge. Capable of continuous feeding, separation, and unloading at full speed. It has the characteristics of compact structure, continuous operation, smooth operation, strong adaptability, high production capacity, and convenient maintenance. Suitable for separating suspensions with solid phase density greater than liquid phase, solid phase particle size greater than 0.002-3mm, and concentration range of 0.5% -40%. Suitable for industries such as chemical, light industry, pharmaceuticals, food, and environmental protection.

4. Compared with belt machines and plate frame machines, centrifuges have the following advantages

(1) The horizontal screw centrifuge uses the principle of centrifugal settling to perform solid-liquid separation. Without a filter screen and filter cloth, it will not cause blockage, while the belt machine and plate frame machine use a filter screen and filter cloth for solid-liquid separation. In order to ensure the filtration performance of the filter screen and filter cloth and prevent clogging of the filter material, high-pressure water needs to be continuously flushed, which consumes a lot of additional energy.

(2) Centrifuges are suitable for dewatering and concentrating various types of sludge. Although belt machines and plate frame machines are also suitable for various types of sludge, a large amount of chemicals need to be added when treating residual activated sludge. Due to the small size of sludge particles, it is easy to clog the filter material, causing difficulties in dewatering, especially for the MBR membrane process sludge currently used in sewage treatment plants.

(3) When the feed concentration changes during the dehydration process of the centrifuge, the slip and torque of the drum and screw will automatically track and adjust, forming a fully automatic operation without the need for dedicated operators. When the concentration changes during the dehydration process, the belt speed, belt tension, dosage, and flushing water pressure all need to be adjusted, which requires high operational requirements; For plate and frame machines, the time and pressure of pressure filtration are closely related to the concentration of the material, and various parameters need to be continuously adjusted as the concentration changes in order to achieve the expected separation effect.

(4) In the centrifuge, even small sludge can be separated from water, so the dosage of flocculant is relatively small. The dosage for general mixed sludge dewatering is less than 5kg/t (dry sludge), the sludge recovery rate is above 95%, and the moisture content of the filter cake after dewatering is 65%~75%. However, for belt conveyors and frame conveyors, the filter belts and filter cloth cannot be woven too tightly. To prevent small sludge from leaking out, more flocculants need to be added to form larger flocs. Therefore, the dosage is often greater than 5kg/t (dry sludge), and the sludge recovery rate is around 90%. The moisture content of the dehydrated filter cake is around 80%.

(5) The centrifuge can operate continuously for 24 hours without the need for flushing water during operation, except for shutdown; And for the belt conveyor and frame conveyor, usually two shifts are arranged every day for operation. The filter cloth and filter belt need to be relaxed and maintained, and the filter cloth needs to be continuously rinsed with high-pressure water during operation.

(6) The centrifuge occupies a small space, is easy to install and debug, and can achieve automated operation. The supporting equipment only includes dosing and feeding conveyors. The centrifuge can operate in a fully enclosed manner, and the workshop and on-site environment are good; However, the belt conveyor and plate frame machine occupy a large area, and in addition to the dosing and feeding conveyors, the supporting equipment also requires auxiliary equipment such as flushing pumps, air compressors, and sludge regulators. Moreover, the overall airtightness of the machine is poor, and cleaning water mist and odors can pollute the environment. If not managed properly, it can also cause mud overflow.

(7) The vulnerable parts of the centrifuge are bearings and seals, and the maintenance cycle for the discharge screw is generally 2-3 years or more. In addition to bearings and seals, the vulnerable parts of belt and frame machines also need to be replaced, including filter belts, filter cloth, and filter plates, which are relatively expensive. The centrifuge can adopt a hydraulic differential control system, which has a high degree of automation and is easy to achieve discharge control. It can also operate at a relatively low differential speed, which can reduce the wear of the screw to the lowest point and improve the overall operating life of the centrifuge.

5. Specifications and technical parameters

6. Automatic control system

The electronic control system can achieve "automatic/manual" operation of the separation host system, feeding system, flocculant dosing system, cleaning system, and mud cake conveying system, realizing functions such as monitoring, fault alarm, and interlock protection of the main equipment operation.