A. H. Lundberg Associates, Inc. provides black liquor concentrator systems to solids in excess of 80%. These systems may be stand-alone, integrated with a multiple effect evaporator system or integrated with a pre-evaporation system. Concentrator systems may be one to three effects.

Lundberg Associates' preferred concentrator technology is flooded forced circulation (FFC). However, depending upon the solids, liquor properties, and number of effects, falling film or mixed falling film and flooded forced circulation technologies may be appropriate. Quite often in systems with high product solids, the main liquor storage is prior to the concentrator with only minimal storage afterwards. Liquor storage after the concentrator may or may not be pressurized.

Salt cake is recommended to be mixed with the liquor prior to the concentrator since many mills experience difficulty in mixing the salt cake with the heavy liquor directly before firing. Further, the addition of the salt cake into the feed to the concentrator will provide seed crystals for crystal formation resulting from the evaporation.

Integrating the concentrator into an evaporator system requires a careful balance between energy costs and capital cost. In the concentrator, the boiling point rise of the liquor becomes an important factor in equipment sizing and the ability to utilize the vapor at a given location in the evaporator system. Integration of a concentrator into an existing evaporator set complicates things even further since the sizing of the existing evaporator vapor head and duct must be considered. A. H. Lundberg Associates, Inc. factors all of these issues into the design of the concentrator system to provide the mill with the most cost effective and economical system possible.