Drying section
For over a decade, economical and environmental constraints have been becoming so important in the paper production that every papermaker tries to reduce waste along the production chain. And because the drying section is one of the most energy consuming part of the paper machine, which shows all the importance of its conception, ABK and its subsidiary M.D.S. (Madeleine Drying Solutions) can supply complete drying sections which meet modern requirements of consumption, efficiency and runnability. Solutions can be found for machine running over 1000 m/min. ABK can supply complete Unorun banks; it can also provide open and closed hoods, complete heat recovery systems, pocket ventilation, blowing rolls, silent drive and rope-less tail transfer.
UNORUN
Primary benefits of Unorun banks is to produce a sheet with elastic properties based on the single tier drying process and to optimize the machine efficiency at the beginning of the drying phase.
The three main parameters that impact the drying process are support, shrinkage and speed.
The tools for controlling these parameters are: the elimination of open draws at the beginning of the drying process, controlled shrinkage in the cross machine direction (CD) during the drying process and finally a consistent and continuous speed.
The support of the sheet has a direct impact on runnability. Total sheet support at the beginning of the dryer section is achieved by the elimination of all open draws. The single tier geometry avoids CD sheet shrinkage. The sheet is sustained and cannot shrink freely as it dries.
Fabric design with blow boxes minimize sheet flapping at high production speeds. Depending on the speed we will offer you the right Unoroll and stabilizer design (grooved roll or vacuroll, mono or duo stabilizer).
OPEN AND CLOSED HOODS
M.D.S. provide hoods designed to get the highest dew point as possible (up to 62°C). It gives to the air circulating in the hood a very good moist-air absorption capacity. It allows lower air consumption as less air is needed to evacuate moist-air from the hood.
The modular construction of hoods makes them easily dismountable and transformable giving a maximum flexibility.
Another advantage of M.D.S. hoods is that panels disposed on each side of the hood and on the roof are totally removable, enabling immediate access for maintenance.
Opening of the hood is assured by large lifting and sliding doors giving an easy access to the machine.
The air management system enables energy savings by regulating extracted and insufflated air.
HEAT EXCHANGERS & ECONOMIZERS
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Energy recovering is of vital interest for paper mills. MDS provide a wide range of high efficient energy recovering equipments with customized dimensions. |
Air-air cross flow exchangers
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This contactless cross flow exchanger enables to retrieve heat from moist-air coming out of the hood. Recovered heat is transmitted to dryer section supply air or ventilation air thanks to the exchanger. |
Steam / Condensates exchangers
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Heat is recovered wherever it is possible even in condensates coming out of the dryer section cylinders. Steam exchanger is generally used to heat dryer section supply air. Heated steam crosses through and gives a part of its heat to supply air. |
Scrubbers
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Scrubbers are direct contact Air-Water devices generally (but not only) used to heat-up white or grey water. Water is dispersed in fine droplets from the hood in the form of moistair. This usually represents the final stage of Heat Recovery, placed after Air-Air and Air-Pressurized Water exchangers, permitting to get back up to 60% of PM steam consumption. This process can be complemented in Coating, Tissue Machines and TADs by a 4th and final stage of Air-Air Heat Recovery dedicated to false ceiling or building ventilation. |
DRYER CYLINDERS
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Dryer are sourced from selected suppliers, and are available either in cast iron or in steel, designed for a working pressure up to 10bar, respecting PED or ASME codes and standards, or any other coding, as required by the final user.
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SILENT DRIVE & QUIET DRIVE
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The silent drive system consists in driving one felt roll every two cylinders in the drying section. Its name comes from the fact it makes a limited noise while PM is running even at high speed compared with previous drive system. Easy access to the section drive side is possible allowing better maintenance and easier paper broke removal. Other advantages are the simplicity of its lubrication and the compact size of the designed batteries. The quiet drive system consists in driving dryer cylinders or unorolls at the end of each battery through hollow shafts. It gives the same advantages as for the silent drive.
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ROPE-LESS TAIL TRANSFER
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The sheet tail enters the dryer section after pressing and is sucked against the felt by means of a blow box. Vacuum rolls and twinstabs assure tail transfer all along the dryer cylinders of a Unorun. In two tier batteries, tail shooters positioned on the doctors transfer the tail from lower cylinders to upper cylinders. Successive vacuum conveyors thread the tail through the calender to the pope. This system of tail threading by shooters and vacuum conveyors is a ropeless efficient solution. It decreases the tail threading time and eliminates production time loss due to rope change. The production is thus significantly increased. It also gives a safer working environment for the workers. |