DDS (Displacement Digester System) is a new pulping technology developed on the basis of RDH cooking system. DDS adheres to the advantages of RDH and improves several technical issues in the RDH process. One of them is that the system has a strong and stable tank area, which is achieved by adding special partitions in the hot and warm black liquid tank. The other is advanced control technology, such as simulated predictive control (MPC), multivariable control, etc., which reduces the impact on cooking operations.
Displacement Digester Systems :Displacement Digester Systems process is the most advanced batch cooking process in the world currently, and has the following advantages compared with traditional cooking process:
The steam consumption is decreased down to 0.6T-0.8T per ton of pulp (Traditional digester consumption is 2.0T-2.5T per ton of pulp)Low kappa, high strength and high yield of pulp can be obtained through deep delignification.
The pulp obtained better bleaching properties. Due to low kappa value and high strength, it is convenient for oxygen delignification, which reduces the consumption of bleaching chemicals and lowers the pollution.
The production process is controlled by computer and human intervention is eliminated to the greatest extent, which ensures the stability and reliability of the system.
Displacement Digester Systems process adopts the principles of the replacement cycle of black liquor in the batch digester and the diffusion cleaning. The consumed cooking liquor and heat are replaced,and completed by cold blowing. The process can utilize black liquor repeatedly, and the lignin, as well as dissolved hemi-cellulose, can be extracted from the cooking system completely during the delignification stage.
In the supplementary delignification stage, the cooking liquor can be re-added. By this way, heat and chemicals can be recycled, and the cooking state is balanced continuously throughout the cooking process, which improves pulp quality and production efficiency.
