The latest technological development of the continuous cooking process

The demands for improved pulp quality have focussed attention on the cooking of kraft pulp. On the other hand, demands for an environmentally sound, economical and efficient pulp production are always present Because the demands on the softwood and hardwood pulp qualities differ from each other, these pulps should also be cooked in a different manner. Lo-Solids(R) cooking method with its low alkali and minimized dissolved solids concentrations in cooking liquid and low cooking temperatures is suitable for both wood species, but offers excellent results especially with hardwood. Further development of Lo-Solids(R) pulping resulted in the EAPC process (Enhanced Alkali Profile Cooking) which is specially designed for softwood pulping when high pulp strength is required The alternating alkali concentrations in various cooking stages, in particular the higher effective alkali (EA) concentration at the end of the cook, result in higher pulp strength and improved bleachability. The desired reaction conditions are obtained by extracting spent cooking liquor from the reaction system several times during the sequence of the cook. Each of these extraction sequences is followed by an addition of make-up cooking chemical and make-up wash water. The modern cooking plant consists of a single vessel hydraulic digester with effective atmospheric gas removal in a Diamondback(TM) chip bin and Lo-Level(TM) feed system. The modern cooking processes create an excellent foundation for the fiberline systems after cooking. The very low reject amount and high bleachability offer opportunities to simplify the fiberline concept.