Pressurized refining systems for wood-based materials

ANDRITZ pressurized refining systems are designed to produce the best fiber quality at low energy demand.

Depending on the raw material to be processed (wood chips, sawdust, shavings, or a mixture thereof), the process starts with pre-steaming in a bin to ensure heating of the raw material as well as continuous and uniform discharge to the plug screw feeder.

Pressurized refining system

Example for wood based raw material - sawmill residuals

ANDRITZ vertical digester

The ANDRITZ plug screw feeder transports the raw material to the vertical digester, compressing the material and stabilizing the moisture level. Each plug screw is designed for the specific raw material type (considering such factors as moisture content and bulk density) in order to ensure best performance over the full capacity range.

Plug screw feeders from 12” up to 26” for high-capacity plants ensure this performance. The plug screw feeder feeds the raw material to digesters with a certain ratio between height and diameter. At this stage of the process, it is important that the raw material has enough time to heat up, and the steam distribution in the digester itself ensures stable conditioning of the material to be processed.

Stable discharge of the raw material to the refiner and the refining process itself are the final stages before the fibers are directed via the blow valve and the fiber diverter valve to the dryer.

With recent developments in refining, ANDRITZ has created a new generation of pressurized refiners. High dewatering efficiency at the plug screw before refining itself ensures that much less water or condensate enters the refiner, thus requiring less drying energy.

Innovations in refiner plate design minimize the electrical energy demand at the refiner itself – ensuring lowest operating costs at highest performance.