Paper production involves several processes in which minor details could lead to a significant increase in costs. The paper dryer section is the portion of this process where the remaining water is evaporated by the supply of heat energy. The paper web is led over dryers that are heated from the inside by means of steam. In this section of the paper mill is where most of the energy consumption takes place.
The dryer constitutes up to 40 % of the total energy costs. Rotating cylinders are heated to remove residual moisture, and at the end, the paper only has from 2 to 9 percent of remaining water. When this operation takes place, a water film always forms due to the centrifugal forces and even a very thin water film layer acts as insulator and inhibits the heat transfer significantly. As a result, more steam is required to equilibrate temperatures, and this situation leads to higher costs, higher maintenance charges, higher steam pressure and a decreased production.
As a result of years of experience, Kurita developed our Dropwise technology, where heat transfer improves by forming a water-repellent film on surfaces.