Hydraulic Headbox for Paper Machines

A hydraulic headbox operates without an air cushion and is fully filled with paper stock. It shares elements with the classical high pressurized closed headbox but includes a built-in stage diffuser and a pulsation damper installed in front of the headbox. This headbox is suitable for paper machines operating with lower consistency and speeds above 300 m/min.

Main Parts

1. Pulsation Damper:

• Installed before the headbox, it includes an inlet section, perforated plate with stage openings, and a top part with a side outlet to the distributor.
• An air cushion forms above the stock level in the damper.
• The stock inlet can be vertical or horizontal.
• Optimal flow through the headbox is achieved by the inlet geometry, perforated plate, and maintaining the proper stock level.
• The primary function is to dampen pulsations in the main stock stream caused by cleaners in the approach flow system.
• Can be designed as a round distributor, ensuring the stock inlet to the headbox is done through distribution hoses with identical diameter and length.

2. Inlet Body:

• Guides the stock in the machine direction and distributes it homogeneously across the paper web width.
• Equipped with recirculation, which is crucial for certain paper properties.
• In cases where the round distributor and headbox are connected through distribution hoses, an inlet body with a constant cross profile without recirculation is used.

3. Stage Diffuser Block:

• Distributes the stock uniformly across the headbox width and produces controlled turbulence to deflocculate fibers.
• Ensures an even flow profile from the diffuser outlet.
• Made from plastic or stainless steel with plastic inserts, allowing optimization for throughput and turbulence intensity.

4. Inlet Chamber with Outlet Nozzle:

• Channels the paper stock to the wire and rectifies its outlet.
• Constructed of stainless steel, with all parts in contact with stock being electrically polished for stability and longevity.

5. Adjusting Equipment:

• Adjusts the headbox slice slip and stock outlet onto the wire.

Cross Profile Control Options

• Manual Control: Top lip shifting mechanisms and dilution water valves.
• Fully Automatic Control: Through QCS of PM control system, including step motors for shifting mechanisms and electronically controlled dilution water valves.

Material

• The headbox is made of stainless steel.
• Stands are made from zinc-coated common steel or stainless steel.
• Base rails are cast iron.
• All parts in contact with stock are made from polished stainless steel.

Accessories

• Headbox stands
• Front and/or back footbridge with ladders
• Source of pressurized air
• Inlet pipes
• Base rails
• Slide valve of the knotter
• Format guides
• Source of dilution water (pump + distribution)

Scope of Delivery

• Complete machine according to the main parts description.
• Optional accessories as per customer’s inquiry.

Applications of Hydraulic Headboxes

• Suitable for narrow assortments of paper where closer flow scope is essential.
• Ideal for machines with speeds above 700 m/min when using a round distributor.

Advantages

1. Higher Operating Speed: Capable of handling speeds above 300 m/min, and over 700 m/min with a round distributor.
2. Favorable Cross-Substance Weight Variations: Ensures uniform paper quality.
3. Even Fiber and Filler Dispersion: Enhances the consistency and quality of the paper.
4. Absence of Air in the Headbox: Prevents foam creation, improving fiber formation.
5. Better Fiber Formation: Results in a higher quality paper sheet.

This hydraulic headbox design ensures efficient stock dewatering and high-quality paper production, with advanced features for optimizing performance and maintaining consistency in paper properties.