How a Dryer Fabric Cleaning System Improves Paper Machine Performance

Most paper mills devote considerable maintenance attention to the wet end of the paper machine, while the dryer section often receives less attention until obvious problems arise. In fact, the condition of the dryer fabric directly affects drying efficiency, energy consumption, machine runnability, and finished paper quality, and these effects are not always immediately visible during daily operation.

This article explains the sources and costs of dryer fabric contamination, when an online cleaning system is required, how different cleaning methods work, how to select a suitable solution based on paper machine parameters, and what factors should be considered when selecting a dryer fabric cleaning system supplier.

Dryer Fabric Contamination Often Causes Greater Losses Than Expected

What Types of Contaminants Gradually Accumulate on Dryer Fabrics?

Dryer fabric contamination usually does not occur suddenly. Instead, deposits gradually accumulate during paper machine operation. By the time operators notice abnormal energy consumption, sheet defects, or changes in machine runnability, contamination may already have been developing for some time.

Typical contaminants include fine fibers, fillers, and dust, which can enter the dryer fabric mesh or adhere to its surface.

On paper machines using recycled fiber, contaminants such as stickies and hot-melt adhesives are more likely to adhere to the dryer fabric and gradually harden under the high temperatures of the dryer section.

Starch, sizing chemicals, and coating chemicals may also enter the dryer section together with the sheet or through splashing and airborne contamination, eventually forming deposits on the dryer fabric.

How Contamination Affects Drying Efficiency, Energy Consumption, and Paper Quality

When the dryer fabric mesh becomes partially blocked, the passage available for water vapor to pass through the fabric and escape is restricted, resulting in reduced dryer fabric air permeability.

The main effects include the following:

Heat Transfer and Drying: Contamination or uneven deposit buildup across the machine direction may reduce uniform contact between the paper sheet, dryer cylinders, and dryer fabric.It can also reduce pocket ventilation efficiency and restrict the removal of water vapor.To maintain the required final sheet moisture, the mill may need to increase steam pressure or reduce machine speed, which directly increases production costs.

Energy Consumption: As dryer fabric air permeability decreases, the steam system and dryer-section ventilation system generally need to operate at higher loads to achieve the same drying capacity.At the same time, the maximum stable operating speed of the paper machine may also be limited.Because this deterioration often develops gradually, the resulting increase in energy consumption can remain unnoticed for a long period.

Paper Quality and Machine Runnability: Uneven dryer fabric contamination may cause CD moisture variations, sheet streaks, localized water marks, wrinkles, or an increased risk of sheet breaks.For packaging paper, printing and writing paper, coated paper, and other grades requiring good moisture uniformity and surface quality, severe contamination may result in customer complaints or downgraded production.

When Is an Online Dryer Fabric Cleaning System Required?

Warning Signs in the Dryer Section That Are Easily Overlooked

Some forms of dryer fabric plugging can be seen directly, while others are mainly reflected in production data.

The following warning signs should be monitored carefully:

• Unit steam consumption continues to increase while production output and paper grade remain basically unchanged.
• CD moisture variation at the reel increases and cannot be reasonably explained by the headbox, press section, steam system, or other process factors.
• Uneven contamination, localized plugging, or uneven residual moisture appears across the dryer fabric, sometimes accompanied by fabric tracking problems, localized tension changes, or reduced runnability.
• During shutdown inspection or reel changes, visible discoloration, stickies, starch deposits, or other contaminants can be seen on the dryer fabric surface.
• Dryer fabric service life becomes noticeably shorter than expected, or frequent shutdowns are required for manual cleaning.

If two or more of these symptoms occur at the same time, the dryer fabric air permeability, contamination distribution, and existing cleaning method should be systematically evaluated.

Offline Cleaning vs. Online Cleaning: When Should Each Be Used?

Offline cleaning is normally carried out during scheduled shutdowns.

It may involve high-pressure water cleaning or cleaning chemicals approved by the dryer fabric supplier or chemical supplier.

Offline cleaning can partially restore fabric permeability in the short term, but it consumes shutdown time and cannot prevent the dryer fabric from becoming contaminated again between cleaning intervals.

An online dryer fabric cleaning system can operate continuously or periodically according to a preset program while the paper machine is running.

It removes contaminants before they become completely hardened and helps maintain relatively stable dryer fabric conditions throughout the production cycle.

For high-speed paper machines, machines using recycled fiber, or production lines with limited shutdown opportunities, online cleaning generally provides greater long-term value.

The final choice should be based on contamination rate, machine speed, paper grade, dryer fabric structure, and acceptable shutdown time.

Many paper mills use both methods: online cleaning for routine maintenance and offline deep cleaning during scheduled major shutdowns.

How an Online Dryer Fabric Cleaning System Works

Online High-pressure Water Cleaning: How Dryer Fabric Contaminants Are Removed

A typical online cleaning system uses a traversing cleaning head that moves back and forth across the dryer fabric in the cross-machine direction.

Special high-pressure nozzles generate concentrated water jets that clean the running dryer fabric point by point or strip by strip.

The high-pressure water loosens and removes fibers, stickies, starch deposits, and other contaminants from both the surface and mesh openings of the dryer fabric.

Important parameters affecting cleaning performance include:

 nozzle design and orifice diameter;

• actual operating pressure;
• distance between the nozzle and dryer fabric;
• jet angle;
• cleaning-head traversing speed;
• paper machine speed;
• dryer fabric material;
• degree and type of contamination

These parameters should be determined during on-site commissioning and reassessed when the paper grade or operating conditions change.

A complete online cleaning system should not rely on high-pressure water alone. 

A more effective cleaning sequence is:

High-pressure water loosens the contaminants → air knives direct loosened contaminants and water toward the suction zone → the vacuum system simultaneously collects and removes wastewater and debris → an outer air knife removes the small amount of residual water remaining on the dryer fabric.

This configuration helps reduce water marks, secondary deposition, and contamination inside the dryer section.

The Supplementary Role of Chemical Spraying: Cleaning and Anti-stick Treatment Are Different

For paper machines with severe stickies or starch deposits, specialized cleaning chemicals may be used, provided that compatibility with the dryer fabric material, paper grade, and mill water system has been confirmed.

These chemicals can help soften or disperse deposits that cannot be completely removed by high-pressure water alone.

In addition, some paper machines use low-dosage release agents or anti-stick agents to form a protective anti-stick layer on the dryer fabric surface and reduce reattachment of contaminants.

These two types of chemicals have different purposes and application methods and should not be treated as the same product.

Chemical agents may be applied continuously at low dosage or intermittently according to contamination conditions.

The appropriate method depends on the chemical properties, paper grade, food-contact requirements, impact on the white-water system, and actual process conditions.

Chemical treatment should complement online high-pressure water cleaning. It should not replace mechanical cleaning and vacuum extraction.

How to Select the Right Cleaning Solution for Your Production Line

Key Parameters That Must Be Matched

Paper machine structures and operating conditions vary significantly.

A cleaning system that performs well on one production line cannot necessarily be copied directly to another.

At minimum, the following factors should be checked during system selection:

• Paper Machine Speed

Machine speed affects the cleaning coverage time per unit area.

The higher the machine speed, the more carefully the cleaning-head traversing speed, nozzle energy, cleaning-track overlap, and vacuum extraction capacity must be matched.

This is necessary to avoid insufficient cleaning or excessive residual water.

• Dryer Fabric Width

Dryer fabric width determines the required cleaning-beam length and effective traversing stroke.

It also affects the number of cleaning heads, nozzle configuration, traversing cycle, and overall mechanical rigidity of the system.

Industrial cleaning systems therefore normally require customized design based on actual site dimensions.

• Paper Grade and Stock Composition

Paper grade and furnish composition determine the dominant contamination type.

For example, a linerboard machine using OCC recycled fiber will have significantly different stickies, filler, and starch contamination characteristics compared with a tissue or printing paper machine using virgin pulp.

• Mill Water Supply Conditions

The available mill water supply affects low-pressure supply, filtration, and high-pressure pump-station design.

For a dedicated high-pressure cleaning system, the working pressure is generated by the high-pressure pump station.

Therefore, in addition to inlet water pressure, the following should also be confirmed: water quality, water temperature, flow rate, filtration accuracy, and stability of the make-up water supply.

Important Design Details

In addition to the basic paper machine parameters, several design details have a direct impact on long-term cleaning performance.

• Nozzle and Filtration System

Nozzle wear or plugging can quickly reduce cleaning performance.

The filtration accuracy, filter replacement method, nozzle inspection interval, and ease of nozzle removal should all be confirmed during system design.

• Traversing Control

The cleaning head should travel smoothly and continuously across the full fabric width.

Traversing speed and reversing positions should be controllable to avoid uncleaned zones, excessive overlapping areas, or permanent water-mark patterns.

• Wastewater Collection and Residual Water Control

Residual cleaning water is particularly undesirable in the dryer section.

When selecting a system, the vacuum capacity, air-knife performance, distance between the cleaning head and dryer fabric, drainage arrangement, anti-plugging design, and safety interlocks should all be evaluated.Cleaning pressure alone should never be the only selection criterion.

What to Consider When Selecting a Dryer Fabric Cleaning System Supplier

Technical Capability and Customized Engineering

Cleaning performance depends heavily on whether the system is genuinely suitable for the specific paper machine.

A simple standardized machine cannot easily accommodate all combinations of:

machine speed, fabric width, paper grade, stock composition, available installation space, and dryer-section ventilation conditions.

A supplier capable of providing on-site measurement, customized engineering, retrofit design, and operating-parameter calculations is more likely to deliver a cleaning system that genuinely matches the production line.

After-sales Support and On-site Service

A dryer fabric cleaning system requires regular inspection of:

filters, nozzles, high-pressure pumps, hoses, traversing mechanisms, air knives, and vacuum systems.

Operating parameters may also need to be adjusted according to paper grade and contamination conditions.

Therefore, the supplier should have continuous after-sales service capability and be able to respond quickly when production abnormalities occur.

Conclusion

Dryer fabric condition is easy to overlook, but deterioration will gradually become visible through increased unit steam consumption, reduced paper quality, higher sheet-break rates, and increased dryer fabric replacement costs.

A properly configured online cleaning system can continuously control contamination without interfering with normal paper production and can help maintain dryer fabric air permeability and stable dryer-section operation.

The Meixin engineering team can provide customized system design based on paper machine speed, fabric width, paper grade, contamination type, and available installation space, together with installation, commissioning, and after-sales support.

You are welcome to provide your paper machine operating parameters so that we can carry out a more targeted technical discussion.

FAQ

Q: Does installation of an online dryer fabric cleaning system require a shutdown?

A:Installation normally requires a planned shutdown. The exact time depends on available installation space and the installation conditions for the cleaning beam and piping. After installation and successful commissioning, the online cleaning system can operate according to a preset program while the paper machine is running, so no additional shutdown is normally required for routine cleaning.

Q: Can high-pressure water cleaning and chemical spraying be used together?

A:Yes, but the purpose of the chemical should first be clearly identified. Cleaning chemicals are used to soften or disperse stubborn deposits, while release agents or anti-stick agents are used to reduce reattachment of contaminants. Both must be compatible with the dryer fabric material, paper grade, and mill water system, and should work together with the high-pressure water, air knives, and vacuum extraction system.

Q: Can one cleaning system handle different fabric widths and different machine speeds?

A:The maximum effective cleaning width, machine-speed range, traversing cycle, and jet energy should be defined during the design stage. Within the designed operating range, the system can adapt to different conditions through program and parameter adjustments. However, if the operating conditions exceed the design limits of the equipment, software adjustment alone will not be sufficient.

Q: Will cleaning water affect sheet moisture?

A:A properly designed system is normally installed on the return run of the dryer fabric or in an area where the fabric is not in direct contact with the paper sheet. Wastewater and residual water are removed promptly by the vacuum and air-knife systems. Only when the jet parameters, suction capacity, and cleaning distance are properly matched and verified during on-site commissioning can water marks and sheet-moisture fluctuations be avoided.

Q: How often does a dryer fabric cleaning system require maintenance?

A:The maintenance interval depends on water quality, operating hours, and contamination level. Routine maintenance items include checking filter differential pressure and filter elements, nozzle wear and plugging, high-pressure pump seals, high-pressure hoses, traversing mechanisms, air knives, vacuum piping, and drainage systems. It is recommended that these items be incorporated into the paper machine's planned maintenance schedule and that inspection records be maintained.

Q: How can we determine whether the existing cleaning system is effective?

A:The following indicators can be monitored and compared over time: dryer fabric air permeability, unit steam consumption, CD moisture profile at the reel, sheet-break rate, water marks after cleaning, cleanliness on both sides of the fabric, and vacuum contaminant discharge. If these indicators continue to deteriorate, the nozzles, filtration system, operating pressure, traversing pattern, cleaning distance, and vacuum extraction capacity should be checked.