Air removal benefits
Improved drainage and formation
Fewer pinholes and spots, less deposits
Increased production and machine efficiency
Improved consistency stability in stock entering the headbox
Deculator and ShortFlow deaeration
Complete or partial deaeration in a paper machine approach system
The ANDRITZ concept for air removal from stock
Complete deaeration of pulp ahead of modern, high-speed paper and board machines is a necessity. Pressure drops and micro-turbulence in the headbox release dissolved gas into entrained air bubbles. ANDRITZ’s experience with more than 900 deculator installations shows conclusively that complete removal of all free and bound air adhering to fibers yields the full benefits of deaeration. However, partial deaeration is sufficient in many applications, such as with several board machines. The ANDRITZ solution for partial deaeration is the ShortFlow deaeration device.
Multi-retention deculator MRD
FlyingWing deculator FWD
Requirements for complete deaeration
- Spraying large quantities of tiny stock droplets creates a large pulp surface area for air to escape efficiently
- Impingement is required to release the bound air and to break down the fiber bundles
- Boiling via vacuum completely removes the air and releases dissolved gases
ANDRITZ multi-retention deculator
Consistency disturbances are one of the causes of basis weight variations and are difficult to stabilize. ANDRITZ multi-retention deculators significantly reduce these disturbances. Stock flows through the feed manifold of the deculator, which divides consistency disturbances into smaller components as they pass through the SPINJET nozzles. Each small component has a different retention time inside the deculator. Due to the counter-direction of flow inside the deculator, random disturbances can be dampened or totally suppressed, depending on their frequency.
ANDRITZ flying wing deculator: combined deaeration and cleaning
The flying wing deculator offers both complete deaeration and efficient cleaning of paper stock. The distribution of cleaner pipes on the deculator’s wings ensures thorough mixing of the stock and attenuation of any short-term consistency variations. The benefits of this design include:
- Higher cleaning efficiency because of fewer dynamic hydraulic disturbances
- Low power consumption – no need for cleaner back-pressure
- Long cleaner life and low maintenance – vacuum core inside the cleaner
- No plugging of cleaner cones
- No control valves necessary for accepts and rejects
ANDRITZ ShortFlow deaeration
ShortFlow deaeration offers partial deaeration where complete deaeration is not needed. Here the wire pit and vacuum air removal tank are combined into one unit, which replaces the conventional wire pit. Deaeration is based on air bubbles rising up due to gravity, which is improved with a vacuum. Short Flow deaeration has a flexible design and can be applied in practically all paper and board machines.
