| Dry Forming of Paper Web | Finland | - | Full scale |
MANUFACTURE OF PAPER AND PAPER PRODUCTS # 28
Background
This case study was submitted on the part of the Working Group on Cleaner Production in Pulp and Paper Industries in the framework of the UNEP IE/PAC Cleaner Production Program with the support of the Technical Research Center of Finland's Non-Waste Technology Research Unit.
United Paper Mills Ltd, located in Kotka, Finland, has been actively involved in the development of the dry forming process since the late 1970's. The first production unit at the Kotka mill started up at the beginning of 1985.
Cleaner Production Principle
Process modification
Cleaner Production Application
The dry forming method can in principle be divided into the following phases: defibration of raw material, forming, binder application, curing, and finishing.
The main raw material, mostly wood pulp, is defiberized in a hammer mill. After this the fibers are transported by means of a fan to the forming section.
Each former consists of two perforated drums rotating inside the forming head. The fibers circulate horizontally between the drums. The accepted fiber material is formed onto the moving forming wire by suction.
After forming, the web is led through heated compactor and embosser rolls.
In the third phase a binder solution is sprayed onto the web. The application is made separately on both sides of the web, each application being followed by through-drying.
Full strength is achieved during the curing as the binder is cross-linked. The curing is also performed in a through-dryer. To improve the final properties the web is led through a finishing calender.
In the conventional process, most of the water which is drained off the sheet in the wire section and pressed off in the press section, is recycled. Some of it is extracted from the process and led back into the watercourse. The evaporated water has to be replaced by fresh water.
In the dry forming process the fresh water demand is only 0,8 liters per one kilogram produced material (air dry). It is totally used to dilute the binder. The dry forming process creates neither waste water nor effluent gases.
The work has progressed from a semicommercial pilot machine to a full scale, fully implemented production unit. The technology is commercially available.
Environmental and Economic Benefits
Dry formed materials have unique absorption and wet strength properties. They are nonabrasive, soft and feel like textiles. The products are suitable for different kinds of towelling and wiping, in health-care, hygiene and for table settings.
The process is non-polluting, there are no waste water problems, and therefore the mill can be located either close to consumers in an urban location or near the sources of raw material.
Investment cost of a dry forming machine is rather low and the economically profitable size of the production plant is small. The capacity of the plant can be enlarged gradually according to market demand.
Constraints
None reported.
Contacts
Review Status
This case study was submitted by the UNEP Working Group on Cleaner Production in the Pulp and Paper Industries, based at the Technical Research Center of Finland (address above) in 1992, as part of a contract for UNEP IE. Before submission, the case studies were reviewed at the Center. They were edited for the ICPIC diskette in June 1997.
Subsequently the case study has undergone another technical review by Dr Prasad Modak at Environmental Management Centre, Mumbai, India, in September 1998.