Deaerator of Approach System

Description:

The ZDE series deaerator of approach system is the key equipment of modern paper machine approach flow system. And this deaerator is located between the reject separator and low-pulse screen-front meshwork, and it can deaerate as much as 90% air from pulp. Moreover, this deaerating machine can keep the pressure, flow rate and consistency of pulp stable before the pulp enters into headbox. So this deaerator of approach system is essential equipment to improve pulp quality and productivity.

Working Principle:

Structure Principle:

1. This deaerator of approach system is made up of multivessel pulp-feeding injection pipe, high-rotation-rate low pressure injection nozzle, overflow weir plate and deaerating device. Pulp from reject separator is sent into the multivessel injection pipe, and then via the high-rotation-rate injection nozzle, the pulp is injected into the top of deaerator where the pulp is dispersed into many small drops and then a layer of liquid film is formed to move around the cylindrical deaerator surface. Meanwhile, because of the boiling from hot vacuum inside the deaerator, free gases overflows out of pulp. The gas bubbles expand at low pressure and then become broken because of impact. Then during the Sanger physical process of injection, impact boiling and more, integrated with air, those broken bubble gases can be effectively separated from each other and discharged out via the suction action of vacuum pump. The air removal rate can be as much as more than 95% and fiber flocculation can be loosened.
Meanwhile, the pulp is dispersed into small independent units according to different pulp consistency, and then after staying in the deaerator for a little while, those pulp flows to the opposite direction due to the function of weir plate. And the fluctuations of the pulp pulse higher than 0.03HZ and pulp consistency can be effectively controlled.
2. Injection: when pulp passes the nozzle of low pressure injection device, the nozzle can increase the exposure area of pulp drops to the largest, so as to increase the air removal rate.
3. Impact: when the pulp is impacted onto the top of deaerator of approach system, the fiber group of pulp is broken to remove the gas bubbles adhered to the fiber.
4. Falling film: when the pulp is injected to the top of deaerator, a layer of liquid film is formed to move around the cylindrical surface, which makes it easier to remove air.
5. Boiling: the self-adjusting vacuum system ensures a corresponding boiling point according to the internal pressure of deaerator, so that the separated air inside the deaerating machine can be discharged timely.

Performance Advantages:

1. This deaerator of approach system can remove all gases from sizing pulp via physical processes of flow injection, falling film, impacting to the surface of pulp flow, vacuum, residence time, etc. It can also stablize the consistency of pulp passing through headbox, pulp flow rate and pressure. Therefore, this deaerating equipment helps to significantly increase the productivity of paper machine approach system.
2. This deaerating equipment can help to avoid slime pulp production, as well as to reduce the retention time of impurities. It contributes to good sheet formation and high quality of paper product.
3. This deaerator helps to dehydrate paper sheets, quickening paper dry process and improving productivity.

Main Technical Parameters:

Type	ZDE1	ZDE2	ZDE3	ZDE4	ZDE5	ZDE6
Specifications (mm)	Φ1400×7000	Φ1400×8000	Φ1400×9000	Φ1900×7000	Φ1900×8000	Φ1900×9000
Retention time of pulp (s)	7-12
Pulp consistency (%)	0.1-0.9
Feeding pulp pressure (mpa)	0.15-0.25
Deaerator weight (kg)	2500	2900	3300	4560	4900	5100