A chemical pulp mill convert large amount of energy and has the potential to become a net producer of both electricity and heat, as well as liquid and solid fuels. The main source for these products is black liquor. To be able to utilize the energy in the black liquor and recover the cooking chemicals it contains, most of the water must be evaporated in the evaporator plant, which is one of the largest consumers of process steam. The black liquor evaporation therefore influences the industries financial result and environmental impact.
The most important parameter for efficient evaporation is heat transfer. Therefore it is important to study this under different conditions to increase the knowledge how an efficient evaporator plant should be constructed. A large hinder for efficient heat transfer is that salts are precipitated at the heat transfer surfaces (so called scaling) and dramatically decreases the efficiency.
The overall aim of this project is to developing paths for more efficient black liquor evaporation, mainly by decreasing scaling. A falling film evaporator with one tube, with special equipment for high quality measurements, is available for the experimental research.
The pilot evaporator located at Chalmers