Award-winning design will make better paper

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ARGONNE, Ill. (Aug. 18, 2006) — Cheaper and more energy-efficient paper production could result from an innovation developed at the U.S. Department of Energy's Argonne National Laboratory. Multiport dryer technology, which won an R&D 100 award from R&D magazine as one of the top 100 scientific and technological innovations in the world during 2005, improves the process of paper drying, the final step in paper production.

In the current process, paper is dried by passing over 30 to 100 large-diameter, steam-heated cylinders, which requires a significant amount of energy and associated capital investment.

Argonne's Multiport dryer has a series of longitudinally oriented passages, or "ports," near the inner surface of the drying cylinders. Basically it is a metal cylinder with long, thin channels indented in the sides from top to bottom. This cylinder fits closely inside the outer drying cylinder, forming tubes that carry steam against the dryer cylinder's surface. This multiport flow configuration increases the rate of heat transfer, drying the paper faster and saving energy.

The basic technology used for paper drying dates back to 1821, when T. B. Crompton patented a method of drying paper continuously by using a woven fabric to hold sheets of wet paper against steam-heated drying cylinders. After it had been dried, the paper was cut at the end of the last cylinder.

Since then, a number of innovations have improved the process, such as packless rotary joints (1933), close-clearance rotary syphons (1965), spoiler bars (1973) and single-tier drying (1987).

"Argonne's Multiport dryer may become one of these major innovations in drying," said mechanical engineer Stephen U.S. Choi. He and senior engineer Ralph Niemann developed the Multiport dryer in collaboration with David France, Gregory Wedel and Gerald Timm.

The Multiport dryer has been in the works since 1996, when Choi submitted a proposal to DOE's Industrial Technologies Program. The invention is now in final prototype development and testing. It is being designed so that it may be installed in existing dryer cylinders. Exact details of the cost are still being determined, but the likely price for the retrofit will be under $10,000, which is less than 20 percent of the installed cost of a new dryer.

David France of the University of Illinois at Chicago designed the Multiport dryer heat transfer test apparatus and produced excellent results when using it to test the technology. Gerald Timm and Gregory Wedel of Kadant Johnson in Three Rivers, Michigan gave the Multiport dryer team a practical guide to the development of Multiport dryer technology. Kadant Johnson is one of the leading equipment suppliers in the paper production industry. Choi said the company is "ideally set up to be a partner in the important bridging stage to commercialization."

The Multiport dryer technology is supported by one U.S. patent, which was issued in June 2002 and is owned by The University of Chicago until 2020. The technology is available for licensing. Funding was provided by DOE's Office of Energy Efficiency and Renewable Energy through its Industrial Technologies Program. — Eva Sylwester