Drying Part of the Paper Machine (PM)

The drying part is the longest section of the paper machine, designed to ensure the necessary drying capacity to meet the set performance goals. It can handle a maximum width of 7,500 mm and is critical in achieving the desired moisture content in the paper web.

Types of Drying Parts Based on Fabric Arrangement

1. Classical (Conventional) Design:

• Drying cylinders (∅ 1,250, ∅ 1,500, ∅ 1,800 mm) in two parallel rows with upper and lower fabric guiding.

2. Slalom Fabric Design:

• Drying cylinders (∅ 1,250, ∅ 1,500, ∅ 1,800 mm) in two parallel rows with single fabric guiding or a single row where the lower row is formed by guide rolls (non-heated, with grooves or bores) with complementary stabilization boxes.
• This setup ensures permanent contact between the paper and the drying fabric, preventing breaks. Vacuum cylinders can be connected directly through a shaft on the drive side or form part of the vacuum with the stabilization box mounted above.

3. Yankee Cylinder Design:

• Features a large drying cylinder (∅ 4,000 mm) with or without fabric.

4. Zero Cylinder Design:

• Includes a smaller drying cylinder (∅ 1,000 mm) at the beginning of the drying part with a complementary stabilization box.

Bearing Structure Types in the Drying Part

• Cast Iron Stands with Steel Supports: Made of welded metal sheets and profiles, preferred for new structures.
• Steel Stands and Supports: Used for reconstructions or when complementing the load-bearing structure.

Drying, Cooling Cylinders, and Guide Rolls

• Types and Design: Located according to the specific chapter dedicated to PM rolls. Bedding lubrication can be either central oil or grease lubrication.
• Cooling Cylinders: Positioned at the end of the drying part to decrease the temperature of the paper web, connected to a closed cooling system.

Elements for Fabric Guiding

• Guides, Stretching, Sensors: For position monitoring and fabric tension, detailed in separate chapters for a PM.

Steam and Condensation System, Recuperation

• Highly Efficient Multi-Grade Drying System: Based on pressure regulation in cylinders.
• Steam-and-Condensate System: Controls the drying curve and regulation for the given production assortment, returning condensate to the boiler house and using waste vapor for air heating in recuperation.

Drying Part Hood

• Purpose: Lowers thermal radiation, prevents damp and warm air leaks, and reduces the amount of air necessary for vaporized water by increasing its moisture content.

Cleaning of Drying Fabrics

• Purpose: Prevents fabric contamination and incorrect dewatering, ensuring no web bundling on guide rolls, performed by subcontractors.

Slitter

• Function: Enables guiding tail slitting into the POPE reel in case of paper breakage, located at the end of the drying part before the cooling cylinder, supplied by subcontractors.

Variations of Silent Drying Cylinder’s Drives

• Half-Silent Drive: Transfers driving force to the last upper and lower cylinder only by a common plugging gearbox.
• Silent Drive: Drives the drying part through the guide rolls of the drying fabrics, with the motor located on the shaft of the guide roll from the service side.

Paper Rope Threading

• Common Version: A double-rope threading system over the entire drying part with automatic threading ropes stretching to ensure continuous machine operation.

These detailed elements and designs ensure efficient and effective drying of the paper web, contributing to high-quality paper production and optimal machine performance.