What Is a Screen Scroll Centrifuge?

The screen scroll centrifuge is a continuous filtering centrifuge in which a screw conveyor turning slightly slower than a conical basket pushes the solids along a screen. Slurry is fed into the narrow end, liquid drains through the screen under centrifugal force and the growing crystal layer is conveyed toward the wide end, where it discharges continuously. Because there is no scraper and no pusher plate, the crystals are moved gently instead of being cut or struck, and because the machine is continuous there is no cycle to interrupt. That is why a screen scroll centrifuge is the classic machine for crystalline salts and granular products.

Working Principle

1) Feed. Slurry is fed into the small end of the conical basket and accelerated to basket speed. 2) Filtration. Liquid passes through the screen and is collected in the casing, while solids build on the screen surface. 3) Conveying and washing. The scroll, running slightly slower than the basket, moves the crystal layer along the screen; wash liquid applied in the middle section displaces mother liquor. 4) Dewatering. As the basket widens the layer thins, exposing more surface and driving moisture down. 5) Discharge. Crystals leave continuously over the wide end of the basket. 6) Filtrate handling. Screen and casing sections can be separated so wash liquor is recovered instead of being lost to the main filtrate.

Key Features

Crystals moved, not cut — a scroll conveys the layer along the screen, so crystal breakage is far lower than with a scraper or pusher.

Truly continuous — no batch cycle, so the machine matches a steady upstream crystallizer or reactor.

Effective multi-stage washing — wash liquid can be applied in stages, so mother liquor and soluble impurities are displaced with little wash water.

Screen choice for the duty — wedge-wire, punched plate or slotted screen; Hastelloy C276 and other alloys available for chloride-bearing liquors.

Compact and sealed — horizontal shaft with a closed casing, so dust and vapor stay inside.

Handles fines better than a pusher — because the layer is conveyed rather than pushed in pulses, it copes with a moderate fines content.

Typical Applications

The LWL screen scroll centrifuge is specified wherever a crystallizer or reactor produces a steady stream of granular solids that must be dewatered continuously without damaging the crystals:

• sodium chloride· ammonium sulfate· ammonium chloride· potassium chloride· citric acid· sodium sulfate· Glauber salt· Hastelloy C276 screen for chloride duty

Selection Guide

Continuous filtering machines differ mainly in how they move the cake, and that decides how much crystal damage you accept:

Choose the LWL screen scroll centrifuge when the solids are crystalline and continuous duty, low crystal damage and effective washing all matter. A pusher machine suits very coarse, uniform crystals; a scraper machine suits fine solids where throughput outranks crystal integrity.

Technical Specifications

Customization & Options

Screen in stainless steel, Hastelloy C276 or duplex for chloride and acidic liquors; basket and casing in 316L; multi-stage wash headers; separate wash-liquor collection; abrasion-resistant scroll flight facing; explosion-proof execution; variable-frequency drive with differential-speed control; CIP and inerting options.

FAQ

The LWL is normally applied to suspensions carrying 10–40% solids with particles from about 0.15 mm to 3 mm, and it will handle coarser material as well. The screen type is selected from your particle size distribution: wedge-wire for coarse uniform solids, slotted or punched screen where you need finer retention. Send a sample and we will confirm the right screen and gap for your distribution.

Far less than a scraper or pusher will. The scroll moves the whole layer along the screen at low relative speed instead of cutting or striking it. For very fragile crystals we can reduce the differential speed, which lowers the mechanical stress further.

Yes. The casing is divided so wash-section filtrate can be collected separately from the main filtrate. That lets you recover a valuable mother liquor, or send only a small wash stream to effluent treatment.

For chloride-bearing and acidic liquors, Hastelloy C276 is the usual answer because it resists pitting and stress corrosion. For neutral, non-chloride duty, stainless or duplex is more economical. We confirm the choice from a liquor analysis.

A screen scroll copes with a moderate fines content because the layer itself acts as a filter. If your solids are predominantly fine, the better choice is a sedimentation machine — we will tell you honestly which one fits your analysis rather than sell you the wrong machine.

Why Jiangsu Shengli Centrifuge

Jiangsu Shengli Centrifuge Manufacturing Co., Ltd. builds this equipment in a 158,905 m2 plant with in-house machining, hard-facing and rotor dynamic balancing. The company holds ISO 9001, ISO 14001 and ISO 45001 certification, CE marking and more than 30 patents, and has supplied machines to customers in over 30 countries. Every unit is balanced and run-tested before shipment, and the balancing report is supplied with the machine.

Request a Quote or a Free Separation Test

Send us a sample of your material and we will run it on a pilot machine, then report the measured moisture, throughput and clarity before you order. Tell us your material and your target, and our engineers will recommend the model, the material of construction and the options that fit.