Drying concepts

Excellence in drying efficiency and runability

    Depending on paper grade, drying concepts aid in ensuring the web is free of wrinkles and reducing the moisture content to approximately 8% with a consistently accurate CD moisture profile.

    Drying concepts consist of a defined number of steam-heated drying cylinders in direct contact with the wet paper as it leaves the press section, which finally leads to a curl-free paper.

    The wet paper after press section contains about 50% water. For water removal, thermal energy (steam) is applied, causing the water to evaporate as it passes through the dryer section.

    Get in touch with our experts

    Portfolio of drying concepts

      DuoDry CC – No more curl

      DuoDry CC is setting new benchmarks for an effective and reliable curl correction. It is the first vertically inverted dryer group, and you benefit from enhanced runability combined with attractive cost and energy savings potential.

      The dryer setion must deliver a consistently accurate CD moisture profile and a fast and smooth transport of the paper web. While the single-tier designs tend to encourage curl, conventional two-tier solutions quickly reach their limits at high speeds. The steam-heated drying cylinders are arranged vertically. This is why the paper web does not need to be remoistened and dried, which results in enormous savings of valuable thermal energy. DuoDry CC is powered exclusively by steam, the most inexpensive heating medium. There is no longer a need for additional moisturizers.

      When developing DuoDry CC, the occupational safety of operating personnel was a key factor. The risk while removing broke is eliminated by using DuoDry CC, as the excess paper drops easily into the pulper or basement.

      As energy efficiency increasingly becomes a significant factor in paper manufacturing, DuoDry CC can be deployed to save valuable thermal energy and increase the machine availability of your mill in the long term.
       

      Voith’s DuoDry CC concept helped us realize the production of low basis corrugated paper of 50 g/m². First, we can achieve at least three to four days with no web breaks, and this can be stretched in some cases up to a week. Second, the precise curl control leads to stable production and operation. As the first company in China and the second in the world to adopt DuoDry CC, we have benefited greatly.
      Mr. Guangdong Ying, Deputy General Manager and Chief Engineer, Sun Paper
      READ MORE ABOUT THE SUCCESSFUL INSTALLATION AT SUN PAPER

      Your benefits with DuoDry CC

      • Sustainable high machine availability and efficiency at very high production speeds
      • Low maintenance effort
      • Significant energy cost savings
      • Lower CO2 emissions

      TopDuoRun – High speed and crease-free transport

      TopDuoRun is a dryer section concept for the highest production speeds. It consists entirely of single-tier dryer groups with drying cylinders arranged on top.

      Installed beneath the dryer cylinders are drilled stabilizer rolls that are suctioned via ProRelease+ or DuoStabilizers. The stabilizers fix the paper web on the dryer fabric so that it is crease-free during the entire drying process and guided from drying cylinder to drying cylinder. If there is a break, the broke falls onto a conveyor belt and is transported into the pulper. By means of short dryer groups at the beginning and end of the dryer section, expansion and longitudinal shrinkage of the web are compensated for, so no creases or breaks occur.

      TopDuoRun is used in dryer sections, especially if high production speeds are required.

      Your benefits with TopDuoRun

      • Maximum runability and efficiency at highest speeds
      • Supported web run along the entire dryer section
      • Reliable ropeless tail transfer

      CombiDuoRun – Preventing the curling tendency of paper

      The CombiDuoRun drying concept dries the paper web on both sides, preventing the curling tendency of the paper.
      The CombiDuoRun is a combination of single-tier dryer groups in the front and double-tier dryer groups in the rear of the dryer section. It is therefore possible to construct the dryer section more compactly with the same drying capacity. Depending on the paper grade, the CombiDuoRun allows reliable operating speeds of up to 1650 m/min.
      The CombiDuoRun is used in the dryer section and enables paper webs to be dried more efficiently. For graphic papers, the CombiDuoRun is mainly used in the after-dryer section of wood-free paper grades.

      Your benefits with CombiDuoRun

      • Contact drying on both sides (curl control)
      • Supported web run in the area of low web strength
      • Ropeless tail transfer in single- and double-tier groups

      Key components

        Voith key components have the highest energy efficiency on the market combined with excellent runability, leading to the lowest operating costs for our valued customers.

        EvoDry – Steel cylinders are the future of drying

        Smart material meets innovative design

        With EvoDry steel cylinders, Voith is revolutionizing the paper drying process and facilitating improved papermaking at the highest level of efficiency. The thinner shell of the EvoDry steel cylinders allows heat transfer to be increased by up to 10%. Above that, the revolutionary design of the Voith drying cylinders enables the maximum level of safety and performance. Using EvoDry, the width of the web can be increased by 160 mm because the shell is welded directly to the head, providing a maximum effective working width. Thanks to their ductile material, EvoDry steel cylinders are especially safe, avoiding the kind of spontaneous breakages that can occur in cast iron cylinders.

        Substantial reduction in investment and running costs

        The use of EvoDry can reduce the number of drying cylinders in the pre-dryer and after-dryer section. Apart from a reduction of the entire dryer weight by up to 260 t, the length of the building can be cut by 6 m, and one drive point can be eliminated. This results in investment costs reduced by EUR 400,000 and an additional drop in annual electricity costs of EUR 80,000.

        The EvoDry steel cylinder offers outstanding performance and is suitable for drying graphic papers as well as board and packaging papers.

        We are equally pleased about our decision to install the EvoDry steel cylinders. We have been able to save space and yet achieve better runability and energy efficiency than before.
        Henning Dippel, Operations Manager BM 6, WEIG-Karton

        Your benefits with EvoDry

        • Investment costs reduced by EUR 400,000
        • Annual electricity costs reduced by EUR 80,000
        • Heat transfer improved by up to 10%
        • Homogeneous surface temperature over width of shell
        • Dryer weight reduced by 260 metric tons
        • Building footprint reduced by 6 m
        • 158 kW lower motor output required
        • 160 mm wider web with same cylinder width
        • More safety thanks to ductile material
        • No risk of steam leakage between head and shell

        EcoHood 65 – Highest energy efficiency and heat recovery

        The Voith EcoHood dryer section hood encloses the dryer section in a special housing that still allows access for operation and maintenance at the highest level of safety.
        EcoHood 65 provides an operating dew point of up to 65°C for the highest energy efficiency. The amount of supply air and exhaust air can be reduced by almost an additional 20% compared to EcoHood 62.
        LEARN MORE ABOUT ECOHOOD

        SteamJoints – Reliably dewatering drying cylinders

        SteamJoints are steam joints with stationary siphons. They reliably dewater at the lowest differential pressure. Costs can be lowered due to low consumption of fresh steam.

        SteamJoints ensure optimal drying cylinder performance at any speed, any pressure and for all paper grades. With stationary siphons, they are an inexpensive alternative to steam joints with rotating siphons, since they ensure reliable dewatering at the lowest differential pressure. In addition, the flow-through steam does not increase as the speed rises, and it remains at the lowest level when the siphon diameter is optimized. The steam flows around the support pipe from both sides, making it heat stable. This provides a secure positioning for the siphon and therefore a consistent heat transfer from the drying cylinder to the paper.

        ThermoBars – Increasing heat transfer in the drying cylinder

        ThermoBars increase the condensate film turbulence in the drying cylinder. The heat transfer in the drying cylinder is improved and drying performance increased. Mini-ThermoBars for the edge area of the cylinder prevent moist streaks at the edge of the paper web.

        Starting at a production speed of about 500 m/min, the condensate forms a laminar ring in the drying cylinder, which reduces the relative heat transfer of the steam to the interior wall of the cylinder. ThermoBars break up this ring by creating turbulence and thus increasing the heat transfer. Drying performance can also be substantially increased. In addition, ThermoBars ensure a consistent condensate thickness over the width, improving moisture cross profile.

        Web stabilizer – Ensuring stable web run

        Optimum web stabilization and tail threading

        With Voith web stabilizers wrinkles, sheet fluttering, edge lifting, frequent breaks and a long down time due to tail threading problems are things of the past.
        Learn more about web stabilizers

        CleanLine Extract4D – Four-directional dryer fabric cleaning

        Contamination in the dryer section reduces productivity by affecting drying efficiency and runnability. Conventional cleaning systems with water jets in one direction only contact a fraction of these contaminants. Thus, higher water pressures must be used, which can cause damage to the dryer fabric. CleanLine Extract4D, with water jets in four directions, overcomes the limitations of conventional cleaning systems.
        LEARN MORE ABOUT CLEANLINE EXTRACT4D

        VentiDoc – Improved drying through good ventilation

        The VentiDoc doctor is for ventilating one- and two-tier dryer sections. It combines excellent doctoring with optimal ventilation of the surrounding dryer pocket.
        VentiDoc combines doctor and blow box, requiring only one installation crosswise to the machine. Hot dry supply air is guided to the blow doctors via an air distribution system. The air arrives in the VentiDoc via a supply air connection on the operator and drive side and is distributed via holes in the doctor body directly in the drying cylinder pocket. Depending on the design of the doctor body, it is blown out in three directions. The moisture present is laterally pushed out of the drying cylinder pockets. Accumulation of moisture is thus prevented, and effective, fast and uniform drying becomes possible. The drying rate in the dryer section is increased, and the system works in a faster, more efficient and inexpensive fashion.
        The VentiDoc doctor is used in the one- and two-tier dryer section of a paper machine.

        Your contact – How can we help you?

          Matthias Neuber

          Product Manager Dryer Section

           

          t +49 7321 37 4169

          Engineered for success

            Our deep expertise is proven in many successful installations all over the world.

            10
            10% increased production with EvoDry steel cylinders
            86
            Up to 86% curl reduction with DuoDry CC
            6
            6% lower electrical energy consumption with EcoHood 65

            Servolution. Service at the next level

              At Voith, the success of the customer takes center stage. Service means delivering customized service solutions and utilizing our full expertise to help our customers reach their goals.

              More safety thanks to ProSafe
              Quick rescue from poorly accessible confined spaces

              The ProSafe rescue shell means valuable time when an employee in a closed container such as a drying, creping and smoothing cylinder as well as boilers and similar containers is dependent on quick assistance. In addition to the hardware, we also offer the appropriate safety training. Contact our expert Michael Neumann (Michael.Neumann@voith.com) and take the decisive step in accident prevention.

              Here you can download the ProSafe product sheet

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