In cellulose industry Freeze Dry Unit has several areas of use. The machine can be used to treat different fractions of sludge that results from the paper pulp process and for dewatering and drying of residues.
The paper starts the journey in the forrest.
In the paper plant the wood is transfprmed to paper pulp and finally paper.
The process results in the final product, paper, but often also residues in the form of sludge
The sludge is dewatered and dried in the Freeze Dry Unit to a dry solid content of 95 %.
The sludge is usuallt dewatered mechanically through a screw press or centrifuge to a dry solid content of 20-30 %.
The dried sludge can, with few transports, be transported for disposal. The reject water can be collected or resused in the process.
The dewatered sludge is transported for disposal. As the sludge is still quite wet there are need for a lot of transports.
As the sludge have a high dry solid content many options for disposal are available. For example it can be used as fertilizer in agruculture, uncunerated, reused in the production or as building material for a final cover for depositions.
Tje sludge can be used as a building material for a deposit cover or in some cases as a fertilizer in agriculture.
The Freeze Dry Unit has been tested on cellulose pulp that has been produced in the process. Tests that have been carried out on pulp between 2 and up to 20 percent dry substance. The final product is a dewatered and dry paper pulp.
Today most of the sludge that is produced in the industry is incinerated. To be able to incinerate the sludge it must be dewatered and transported to an incineration facility. After dewatering the sludge contains about 70-80% water. This results in high transportation costs as it is mostly water that is transported. The sludge also must be incinerated with support fuel to ensure an effective process. Afterwards the ash can be used as construction material. In countries where it is allowed it can be used as landfill.
With Freeze Dry Unit a high dry solid content is achieved through an entirely natural process. This reduces the need of transports and the costs associated with these. A high dry solid content also enables effective incineration with a high energy outtake. Without the use of support fuel phosphorus from the ashes can be extracted and recycled. A dry sludge without polymers or other chemicals can also be reused within the processes at the plant or used to create a valuable new product.