Displacement Digester System

batch cooking system

The displacement digester system is also known as DDS cooking system.  As the most advanced batching cooking technology in the world, it applies for wood pulp or bamboo pulp project with 50-300 thousand tons annual output.

Displacement digester specifications:

Model ZJG3 ZJG4 ZJG5 ZJG6 ZJG7 ZJG8 ZJG9
Effective volume (m³) 110 135 175 225 250 330 400
Diameter (internal) (mm) 3600 4000 4500 4500 4500 5600 5800
Design pressure(Mpa) 0.9/1.2
Design temperature (℃) 180/240

The displacement digester cooking system is made up of conveyor, digester, storage tank, blow tank, separator, heat exchanger, foam breaker, black liquor filter and pump, and other equipment.

cooking equipment

How to operate DDS cooking system?

The displacement digester cooking system include four basic units, such as cooking, heat exchange, black liquor filter and exhaust gas separation. The cooking process can be divided into 6 steps as following:

  1. Digester filling: transport wood chips to digester with conveyor, add recyclable black liquor, and remove air from digester with air exhauster.
  2. Dipping process: use pump to transfer black liquor from dipping tank into pulp digester, add cold white liquor quantificationally, displace black liquor from last step, and exhaust air from digester.
  3. Low-temperature cooking process: use pump to transfer black liquor from dipping tank into pulp digester, add hot white liquor quantificationally, displace the black liquor of dipping process, and heat the digester up to the cooking temperature.
  4. High-temperature cooking process: compared to common batching cooking process, use external circulating system to heat up to cooking temperature.
  5. Displacement washing process: use the black liquor of washing and screening process to displace the black liquor of digester.
displacement cooking

Advantages of DDS cooking system

  • Less steam consumption: the steam consumption of per ton pulp is less than 0.8 ton, save 60% steam consumption.
  • High production efficiency: large filling capacity, high coarse pulp yield, short digester cycle, high production efficiency.
  • Flexible pulp processing: apply for wood or bamboo fiber materials with bad quality and low qualified rate.
  • Reliable and stable system: automatic control, fully reduce man-made factors, safety and reliability.
  • High pulp quality: even and stable pulp quality.
  • Less environmental pollution: adopt cold blow technology, no noise, reduce 95% of waste air, less chemical consumption, less pollution load.
  • Washing function: the washing efficiency of displacement washing is equal to vacuum drum washer.

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