Abstract
Historically, paper has been consolidated by wet pressing followed by drying on steam cylinders or by other low intensity evaporative processes. Although these time-tested pro cesses will continue to be the mainstay of papermaking for some time, they are now being challenged by new systems that exploit the interactive effects of increased pressures and temperatures. We want to review our understanding of these hybrid processes and the unprecedented performance potential they offer. At the same time, we want to integrate .them into a common context with the more conventional web consolidation processes. To do this, we define four classes of systems mechanical, thermal, thermal with restraint, and thermomechanical. Each class uses mechanical, thermal, and interactive effects in a unique way to determine water removal rates, energy efficiency, property development potential, and machine size and complexity. In a parallel and unifying fashion, each class also occupies a distinct region on coordinates of specific energy consumption and working temperature. This diagram is offered as a starting point for integrating wet pressing, hot pressing, cylinder drying, press drying, Condebelt drying, impulse drying, and others into four distinct classes of web consolidation systems.
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