Screw classifier for ash transport

This is a process machine which receives final ash fragments from the burner in a power plant. The screw conveyor for ash transport is placed in the bottom under the last ash take-out from the burner.

The ash fells into a water tank. In the bottom of the water tank, there is a screw conveyor that lifts up the humidified ash and ensure that the water is drained out from it, before it fells out into the container.

The water level is regulated with 2 sensors placed in different hight (low level/high level). The water is connected to a solonoid valve that receives the signal from the sensors. It is a very plain and stable solution, which ensure a constant water level in the tank.

The machine is manufactured as a complete system and checked for water tightness before shipping to the customer.

BEMA has designed the complete solution and assisted the final client under the installation proces to ensure that it fulfills the idea of drainage and ash-transport as a complete solution.

The screw conveyor solution is a much more stable and plain solution compared to a chain conveyor or similar solution. The only moving part is the screw rotor which has a water tight bearing in the bottom. For easy maintenance, the bearing is replaceable from the outside.

See another example of a screw classifier here

Technical FAQ for the Screw Classifier for Ash Transport

1. How does the screw classifier manage ash and water separation?

The classifier receives hot ash fragments directly from the burner and drops them into a water tank. A screw conveyor installed at the bottom lifts the humidified ash upward while allowing water to drain through the system before the ash exits into a container. This ensures controlled cooling and efficient dewatering of the ash.

2. How is the water level in the tank regulated?

Two level sensors—one for low level and one for high level—continuously monitor the water height. These sensors control a solenoid valve that automatically adjusts water inflow, maintaining a stable and consistent water level during operation.

3. What design features ensure long-term mechanical reliability?

The system has only one moving component: the screw rotor. Its bottom bearing is fully water‑tight and designed for external replacement, minimizing downtime and simplifying maintenance. The sealed construction also prevents water ingress into mechanical components.

4. How is the system validated before delivery?

Each screw classifier is manufactured as a complete, integrated unit and undergoes a full water‑tightness test prior to shipment. BEMA also supports installation on-site to ensure the classifier performs according to the intended ash‑handling and drainage concept.