The purpose of cooking the agro raw material is to chemically dissolve the lignin & other organic compounds in order to obtain unbleached pulp. The cooking of agro based raw material like bagasse is carried out in horizontal continuous Tube Digester at the temperature of 160 Deg. C & pressure of 6.5-7 kg/cm2. The Main components of the digester system are.

• Screw feeder
• Inlet Chamber with Stop Valve.
• Digester tubes.
• Cold Blow Discharger
• Blow House.

The washed raw material from Aqua Separator is conveyed by a Belt Conveyor to the metering screw conveyor in the digester house. Bagasse from the Metering Screw conveyor is fed to the pin feeder & the excess raw material is returned back to the wet washing plant.

In the Pin feeder, Raw material is fed to the screw feeder to make it a compact type mass before it enters to the inlet chamber.

The Cooking chemical & steam is given at the inlet chamber, where it is mixed with the raw material before entering the digester tubes. A pneumatically operated Blow back valve is provided in the Inlet chamber to avoid blow back of the raw material in case of improper feeding before the digester tubes.

Digester is having two horizontal tubes equipped with horizontal screw conveyors- which conveys the material from first tube to the second tube. The steam is injected in the first tube to control the temperature & pressure. The Speed of the screw in the digester tube is maintained to obtain the desired Kappa Number.

The cooked Raw material- that is pulp, is blown to the Cold Blow Discharger, where the cold black liquor is injected. From Cold Blow Discharger- it is blown to Blow Tank, which acts at a storage for the cooked pulp.