Rotary drum filter Practical Guide: Master Key Points from Core Components to Troubleshooting-Xinxiang Yinuo Machineries Co., Ltd.

Rotary drum filter

The Rotary drum filter is a highly efficient solid-liquid separation device widely used in chemical, pharmaceutical, food, and other industrial sectors. Its operation primarily relies on vacuum suction, achieving filtration and separation of mixed materials through the coordinated action of drum rotation and the vacuum system.

Construction of the Rotary drum filter

The structural design of the Rotary drum filter centers on “continuous operation” and “high-efficiency separation,” primarily comprising the following seven components:

Component Name	Core functionality	Key design points
Rotating drum	The core carrier of filtration, with a negative pressure chamber inside and a filter cloth covering the outside	The material is mostly stainless steel/cast iron, with a diameter of 0.5-3m and a length of 1-6m; the surface has uniform holes (with a diameter of 1-3mm) for liquid delivery
Slurry tank	To accommodate the waiting filter slurry and support the rotation of the drum	A stirring device is installed at the bottom to prevent particle settling; Set up slurry inlet and outlet on the side (to maintain stable material level)
Vacuum system	Provide negative pressure power, including vacuum pump, vacuum tank, gas-liquid separator	Vacuum pumps are mostly water ring/Roots type. Vacuum tanks are used to stabilize negative pressure, and gas-liquid separators prevent liquids from entering the vacuum pump
Filter cloth system	Intercept solid particles and allow liquids to pass through, including filter cloth, tensioning device, and guide roller	The material of the filter cloth is selected according to the material (such as polyester, nylon); Regular replacement is required, and the tensioning device ensures that the filter cloth fits snugly against the drum
Unloading device	Stripping filter cake, divided into scraper type, air blowing type, and rope type	The gap between the scraper and the drum is 0.1-0.5mm (adjustable); Air blown type requires controlled compressed air pressure (0.2~0.5MPa)
Washing system	(Optional) Clean the filter cake, including spray pipe, detergent storage tank, flow control valve	Spray pipes should be evenly distributed to avoid filter cake dispersion; The flow rate of the washing solution is adjusted according to the thickness of the filter cake
Transmission system	Drive the drum to rotate, including motor, reducer, gear/chain transmission mechanism	Adjustable speed (0.1~5 r/min), controlled by a frequency converter to match the filtration speed of different slurries

Design Principles of Rotary drum filter

The core design of Rotary drum filter lies in their drum structure and vacuum system. The drum typically consists of multiple sector-shaped filter plates covered with mesh or filter cloth to intercept solid particles. As the drum rotates driven by a motor, the filter plates immersed in the slurry adsorb solid particles while liquid drains through the mesh or cloth.

The vacuum system generates negative pressure via a vacuum pump, creating a low-pressure zone on the inner side of the filter plates to enhance solid particle adsorption. As the drum rotates, the plates laden with solids gradually exit the slurry and enter the vacuum drying zone for further liquid removal. Finally, the solid particles are discharged by scrapers in the unloading zone, completing the filtration process.

Manufacturing Materials

Material selection for different components requires balancing three key factors: corrosion resistance, strength, and cost. Common materials include:

Component	Common Materials	Applicable scenarios
Rotating drum	304/316 stainless steel (moderately corrosion-resistant), cast iron (non corrosive, high viscosity material), titanium alloy (strongly corrosive)	Select 316 stainless steel for chemical (acid/alkali slurry); Mining (coal slurry, ore) selection of cast iron
Slurry tank	304 stainless steel, fiberglass reinforced plastic (FRP, lightweight and corrosion-resistant), carbon steel lining adhesive (strong corrosion, low cost)	Choose fiberglass for environmental protection (sewage); Metallurgical (including heavy metal slurry) selection of carbon steel lining adhesive
Filter cloth	Polyester (acid resistant, cost-effective), Nylon (alkali resistant, wear-resistant), PTFE (high concentration acid/high temperature resistant)	Select food grade polyester for food (starch, sucrose); Pharmaceutical (organic solvent) selection PTFE
Scraper	Stainless steel (ordinary material), tungsten carbide (wear-resistant, such as ore filter cake), polytetrafluoroethylene (anti sticking)	Choose PTFE scraper for viscous materials (such as sludge) to avoid filter cake sticking to the blade
Pipeline/Valve	304/316 stainless steel, UPVC (low pressure, acid resistant)	Choose stainless steel for vacuum pipelines (to avoid negative pressure deformation); Optional UPVC (low-cost) for detergent pipeline

FAQ

What causes a sudden drop in filtration speed?

① Increase vacuum pressure, but do not exceed 0.08 MPa to prevent filter cake from clogging the filter cloth;

② Reduce drum rotation speed;

③ Inspect the filter cloth for damage.

What should be done if filter cake discharge is incomplete and sticks to the filter cloth?

① Adjust the scraper gap to reduce it to 0.1-0.3mm

② Enable air-blow discharge and increase compressed air pressure to 0.3-0.5MPa

③ Replace with anti-adhesive filter cloth, such as PTFE-coated filter cloth

④ If material viscosity is high, add a small amount of filter aid to the slurry.

How to address excessive noise during equipment operation?

① Vacuum pump oil shortage: Check vacuum pump oil level/liquid level;

② Transmission system wear: Replace worn parts and add lubricating oil;

③ Drum imbalance: Adjust slurry feed rate to ensure uniform filter cake distribution.

How to prevent equipment damage caused by corrosive slurries?

① Select corrosion-resistant materials such as 316 stainless steel, titanium alloys, or fiberglass-reinforced plastic (FRP);

② Regularly inspect internal surfaces like drums and slurry tanks for corrosion marks and repair promptly;

③ After shutdown, flush equipment interiors with clean water to prevent residual corrosive materials.