Paper making and fiber liberation – Apparatus – Automatic control
Reexamination Certificate
1999-07-21
2001-09-18
Silverman, Stanley S. (Department: 1731)
Paper making and fiber liberation
Apparatus
Automatic control
C162S254000, C162SDIG004, C162S198000, C162S262000, C162S252000, C162S263000, C162S258000, C162S259000, C700S127000, C700S129000
Reexamination Certificate
active
06290816
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to paper machines, and, more particularly, to a control system used to control physical components of the paper machine.
2. Description of the Related Art
A paper machine receives a prepared fiber suspension and produces a fiber web, such as a paper web. The physical parameters of the fiber suspension which is supplied to the paper machine, such as the pressure, temperature, chemical content, etc. in turn affect the physical characteristics of the fiber web manufactured by the paper machine. It is known to laboratory test a small portion of the fiber web to determine the physical characteristics thereof. After the fiber web is tested, valves, feed screws, pumps or the like may be manually actuated to add a predetermined amount of energy (e.g., heat) or chemical (e.g., calcium carbonate, titanium dioxide, etc.) to the fiber suspension to affect the physical characteristics of the manufactured web. Since this process is manually adjusted, the delay time between obtaining a sample of paper and finally adjusting a device within the approach flow system may be extensive. This means that a relatively large amount of paper may be produced which does not have optimum physical characteristics.
What is needed in the art is a paper machine which automatically adjusts for at least some of the physical parameters associated with the fiber suspension to thereby improve the quality of the fiber web.
SUMMARY OF THE INVENTION
The present invention provides a chemical process controller which receives input signals from a plurality of sensors spaced along the length of the paper machine, and which controls various control modules of an approach flow system which provides a fiber suspension to a wet end of the paper machine.
The invention comprises, in one form thereof, a paper machine for making a fiber web, including an approach flow system including a plurality of control modules. Each control module controls one of a plurality of adjustable input parameters. A wet end receives a fiber suspension from the approach flow system and includes a headbox which discharges a fiber suspension with a known cross sectional profile onto a wire. A press section, forming section and drying section are used to press, form and dry the fiber web, respectively. A plurality of sensors are respectively positioned in association with the approach flow system, wet end, press section, forming section and/or drying section. Each sensor is configured to sense a physical characteristic of the fiber web and provide an output signal indicative thereof. A chemistry process controller is coupled with each sensor and each control module within the approach flow system to define a closed loop control system. The chemistry process controller controls operation of each control module.
An advantage of the present invention is that the physical parameters of the fiber suspension are controlled using a closed loop control system, thereby avoiding the necessity to manually adjust valves, pumps or the like.
A further advantage is that output signals from the sensors may be utilized almost instantaneously to provide a fiber suspension with desired physical parameters to the wet end of the paper machine.
REFERENCES:
patent: 5715158 (1998-02-01), Chen
patent: 6086716 (2000-07-01), Watson
Halpern M.
Silverman Stanley S.
Taylor & Aust P.C.
Voith Sulzer Paper Technology North America Inc.
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