Principle of Operation
The Parason Deinking cell consists of a number of cells in series with an elliptical cross-section with a baffle extending over the entire length to separate suspension chamber. Air (at the atmospheric pressure) and pulp stock to be de-inked is introduced into the cell chamber through a specially designed injector nozzle. Flow-through nozzles generate a negative pressure that sucks in the necessary process and generates microturbulence resulting in widely ranging bubble sizes enabling efficient removal of an equally wide range of particle size.
This enhances brightness to a high degree and reduces dirt, specks and stickies efficiently. The injectors optimize the quantity of the air injected and the size of the bubbles generated. The pulp stock free from the ink is pumped from the bottom of one cell to the next cell. The ink laden foam overflows to the foam chamber with the help of a motorized paddle.
System Experience and Process Know-How
Flotation process is operated in a continuous mode and helps to remove ink particles efficiently. Since the cells are interconnected by opening only, a level control system is required for the entire flotation machine.
The primary flotation stage ensures the highest possible stock purity and the secondary stage optimized flotation ensures the fiber recovery to maximize the yield without any loss of brightness and cleanliness. A Deaerator cyclone removes air from the stock and usable fiber is recovered from the foam.
Unique Features of the Parason Deinking Cell
- Highest possible degree of brightness is achieved. Improved optical cleanliness in recovered paper stock
- No sizing restrictions. Single level control loop operation
- Optimized flotation maximizes the yield at the secondary stage without any loss of brightness and cleanliness
- Very low fiber loss in the de-inking process as the foam is treated in a cascade process
- High percentage of ash in reject resulting in low fiber losses