Hot Paper

The aim of the HOT Paper project  is to reduce energy use in paper production by increasing process water temperatures. The theory behind this is that with increased temperatures, water viscosity increases, which leads to increased water removal in the wire- and press sections. Therefore, less evaporation is needed in the drying section, where energy use is highest.

In this study, we calculated how and in how far these high temperatures can be reached by using excess heat from the mill. The energetic an economic (dis)advantages are mapped. The study shows highest potential (12-17% energy savings in the drying section as compared to the reference situation) for heating process water with waste heat from the hood after increasing the dewpoint of the drying air. Spontaneous water evaporation on the wire should be kept as low as possible (e.g. by means of a hood over the wire), especially by temperatures above 55°C, in order to avoid energy losses. We further concluded that a generic temperature increase  of process water is only efficient when heat is used that is not useful in other parts of the process. Exhaust heat from the hood should first be used for preheating supply air, fresh water supply, and for space heating.

Although it was demonstrated that energy can be saved by using waste heat to increase process water temperatures, it is still unclear if the use of waste heat for this purpose is the most efficient use of waste heat. If the quality of waste heat (temperature) can be increased, more efficient possibilities for its use might appear (e.g. the production of electricity). The identification of those waste heat applications with the highest potential in paper industry should be further investigated.

Contact:
Jobien Laurijssen j.laurijssen@kcpk.nl