Trough screw conveyors for slag

Through screw conveyors for slag delivered to a straw fired power plant. The screw conveyors are replacing existing screw conveyors where intermediate bearings are used.

Why shall you avoid intermediate bearings in screw conveyors for slag and ash?

1. The ash from the transport will no matter how distribute into the intermediate bearing
2. After a very short time the intermediate bearing will break down caused by the abrasive material
3. No matter how low you decrease the filling degree of the through screw conveyor, intermediate bearings shall be avoided

Through screw conveyors are very suitable for transporting ash coming from the boiler process in a powerplant.

What are the advantages for using trough screw conveyors?

1. The screw conveyor only have one moving part – the screw rotor
2. The bearings are sitting outside of the machine and have no contact with the material
3. If the ash is highly abrasive you can you Hardox steel to reduce the wear on the screw flights
4. You can keep the material completely closed in a trough screw conveyor

See another example of screw conveyors for ash transport

Key factors to consider when you design screw conveyors for slag and ash

1. The filling degree shall be low – app. 10%
2. If possible keep the inclication of the trough screw conveyors below 15°
3. If the inclination exceeds 15° consider to use Hardox steel for the screw flights
4. Always use bolted lids to ensure tightness of the screw conveyors towards the exterial environment

When you order through screw conveyors in BEMA we always offer to supply all relevant components such as:

1. Supporting cribs
2. Legs for carrying the screw conveyors
3. Inlet and outlets for easy adaptation during installation
4. Chutes and other relevant equipment

BEMA’s design department with our own engineers and technicians have many years of experience to design complete solutions. The additional components can save you valuable installation time and cost for your screw conveyors.

FAQ: Trough Screw Conveyors for Slag

1. What are trough screw conveyors used for in slag and ash handling?

Trough screw conveyors are designed to transport abrasive materials such as slag and ash from boiler processes in power plants. Their enclosed design ensures safe, controlled movement of material while minimizing dust and environmental impact.

2. Why should intermediate bearings be avoided in slag conveyors?

Intermediate bearings quickly fail when exposed to ash and slag. Abrasive particles inevitably enter the bearing, causing rapid wear and breakdown—even when the filling degree is kept low. For this reason, intermediate bearings are not recommended for ash or slag transport.

3. What advantages do trough screw conveyors offer for abrasive materials?

They have only one moving part—the screw rotor—reducing maintenance needs. Bearings are placed outside the material flow, preventing contact with abrasive ash. When handling highly abrasive material, Hardox steel can be used to extend the lifetime of the screw flights.

4. What should be considered when designing screw conveyors for slag?

Key factors include maintaining a low filling degree (around 10%), keeping the inclination below 15° when possible, using Hardox for higher inclinations, and installing bolted lids to ensure tightness. These considerations help secure long‑term performance and reliability.