US3253740A - Apparatus for continuous measurement and control of shive content - Google Patents

Description

y 31, 1966 M. A. KEYES 3,253,740

APPARATUS FOR CONTINUOUS MEASUREMENT AND CONTROL OF SHIVE CONTENT Filed Dec. 10, 1964 I NVEN TOR.

J/orv'on /i Hqyes TTOR NE YS United States Patent 3 253,740 APPARATUS FOR CONTINUOUS MEASUREMENT AND CONTROL OF SHIVE CONTENT Marion A. Keyes, South Beloit, lll., assignor to Beloit Corporation, Beloit, Wis., a corporation of Wisconsin Filed Dec. 10, 1964, Ser. No. 417,376 9 Claims. (Cl. 222-52) The present invention relates to a continuous device for controlling the quantity of uncooked chunks or shives in a papermaking process.

The problem of shive control is particularly troublesome in semichemical pulping processes where it is important to achieve the correct degree of refining of the pulp before it is formed into the web. In such systems, it is necessary to operate between the extremes of too little refining, in which case there is a loss of stock forming material, and too much refining prior to washing, which adversely affects the drainage properties of the stock.

The system of the present invention provides a continuously operable sensing and recording mechanism for monitoring the shive concentration in the stock feed. In accordance with the invention, the stock from a headbox is supplied under a constant hydrostatic head to a metering tube in which there is an adjustably positionable constriction means in the form of a plug. The constriction means and the internal wall of the metering tube cooperate to define an orifice of size such that the fibrous portion of the stock can pass freely therebetween, but the shives are trapped and eventually build up a deposit in the orifice. Fluid flow sensing means are provided to sense the flow rate of material passing through the metering tube, and when an accumulation of the shives causes a diminution of the flow rate of stock through the tube, the flow sensing means operates other devices to first withdraw the plug and thereby enlarge the orifice in the tube, second, to flush the tube with water while diverting the stock fiow therefrom, and third, to send a signal to a counting device. A timer is provided to control the introduction of flushing water to a predetermined time interval. At the conclusion of the interval, the apparatus is reset, the plug moved back into constricting relation within the tube, and the flow of stock through the metering tube is resumed. The counter, actuated by the impulses from the relay or other device which actuates the various mechanisms associated with the metering tube, is cycled by means of another timer device so that it counts the number of actuations of the relay for a predetermined time interval dependent upon the setting of the timer. This intelligence is then transferred to a recorder-controller which, in a preferred form of the invention, compares this intelligence with a control. When the number of actuations of the relay per interval of time exceeds that which has been programmed into the recorderc-ontroller, the recorder-controller issues a control signal which can then be used to modify a process variable in the direction of reducing the amount of shives retained in the stock.

An object of the present invention is to provide a continuously operable shive monitoring and measuring device for papermaking operations.

Another object of the invention is to provide a continuous system for monitoring shive contents to produce a control signal which can be used to adjust the shive concentration to desired limits.

Still another object of the invention is to provide a device for the continuous monitoring of stock which is completely automatic in operation.

Other objects and features of the present invention will become apparent to those skilled in the art from the following detailed description of the attached sheet of 3,253,740 Patented May 31, 1966 drawings which illustrates a preferred embodiment of the invention.

In the single figure of the drawings, reference numeral 10 indicates generally a headbox for supplying papermaking stock at a constant hydrostatic pressure. Stock is introduced into the headbox 10 through an inlet line 11, and a pair of weirs 12 and 13 are positioned in spaced relation within the headbox 10. Stock is continuously removed from the headbox 10 in the region between the Weirs 12 and 13 by means of an outlet line 14 while the overflow beyond the weir 13 is returned to the process stream by means of a line 16.

The stock in the line 14 is directed to a four-way valve 17 which selectively introduces the stock or water from a water line 18 into a metering tube generally indicated at reference numeral 19 in the drawings. The metering tube 19 is generally cylindrical in configuration, and contains an outwardly flared bell portion 21 at the discharge end thereof. Located in the bell-shaped discharge portion 21 is a conical plug 22 which is adjustably positionable within the discharge outlet 21. The plug 22 is mounted on a stem 23 which is received within a cylinder 24. A piston 26 is carried by the stem 23 and is operable in response to air pressure injected therein to move the plug 22 up and down, and thereby provide a greater or a lesser constriction to the flow of material through the metering tube 19. Improved results are obtained if the plug 22 is also rotated, and to this end, there is provided a pulley 27 driven by a belt 28, and having a key therein engaging an elongated slot 29 formed in the stem 23. The belt 28 thus provides a driving connection to the stem 23, while permitting vertical movement of the stem 23 when required.

The stock after passing through the valve 17 actuates a fluid flow sensor 31, such as a flow meter. The stock in normal operation then passes into the metering tube 19 and flows between the inner wall of the tube 19 and the plug 22, the two defining a restricted orifice 32 which is of suflicient size to permit free passage of the fiber containing stock through the bell-shaped discharge outlet 21, while retaining larger shives therein.

The flow meter 31 is in a line containing a valve 33 and a flow controller 34 which is connected to a pneumatically operated relay 36. An air line 37 supplies compressed air for operation of the relay. Closing of the relay 36 operates to energize a solenoid 38 which changes the position of the four way valve 17 from one in which stock is introduced into the metering tube 19 to one in which water from the line 18 is introduced into the metering tube 19 to flush the accumulated residue from within the column. During flushing, the stock is diverted to the process stream by means of a line 39.

Closing of the relay 36 also operates to energize a solenoid 41 which actuates a three way valve 42. Compressed air is introduced through the valve 42 from an air line 43. Upon actuation of the solenoid 41, the air in the line 43 is injected into a line 44 which supplies the air under pressure to the cylinder 24 at a point above the piston 26, and causes the piston to move downwardly, and carry with it the plug 22. The removal of the constriction from the throat of the metering tube thereby pro vides for more complete flushing of the accumulated materials from within the metering tube during the flushing cycle.

The duration of the flushing cycle is determined by the setting of a timer 46 associated with the relay 36. The timer 46 provides for opening of the four way valve 17 for a predetermined interval of time, so that each flushing cycle is of exactly the same duration. After the interval prescribed by the timer 46 has expired, the pneumatic relay 36 is deenergized, thereby deenergizing the solenoid 38 and the solenoid 41. When this occurs, the flow of stock into the metering tube 19 is resumed through the four-way valve 17 and the flow meter 31. The constriction provided by the plug 22 is again re-introduced into the discharge end of the metering tube 19 by providing air pressure on the opposite-side of the piston 26, by means of a line 47 connected to the three-way valve 42. A normal operation is then resumed, until such time as the How meter 31 again senses a reduction in the fiow through the metering tube 19 caused by the accumulation of shives in the orifice 32.

The number of operations of the pneumatic relay 36 per specified interval of time is used as a measure of the shive concentration in the stock. Each time the pneumatic relay 36 operates to commence flushing of the metering tube 19, a signal pulse is supplied by means of a line 48 from the relay 36 to a counter 49. The counter 49 is cycled by a timer 51 to operate over a predetermined time interval. At the conclusion of such time interval, the counter 49 is reset by operation of the timer 51, and the accumulated counts which have been fed to the counter 49 are transmitted by means of a line 52 to a recorder-controller 53. In the latter, the intelligence inherent in the transmission of the data from the counter 52 is compared with a predetermined program, to thereby sense automatically whether the amount of shives in the stock has become excessive. To take a specific example, if the timer 51 is set for a 15-minute interval, and it has been predetermined that the number of flushings for a l5minute period which would be characteristic of a properly refined stock is three, and the counter 49 provides four impulses during its cycling time, the recordercontroller 53 immediately puts out a control signal through a line 54 which modifies a process variable in the direction of reducing the amount of shives in the stock. This can be accomplished by using the control signal to set the plug position on a prebrealter refiner, or the reject rate on the stock screen.

From the foregoing, it will be understood that the device of the present invention provides a completley automatic system for monitoring and controlling the amount of shives in a papermaking stock. The system lends itself to complete automation since no operator is required once the timers and the recorder-controller have been preset.

It should be understood that various modifications can be made to the described embodiments without departing from the scope of the present invention.

I claim as my invention:

1. A continuous shive control device comprising a metering means, means for supplying stock to said metering means under a constant hydrostatic head, a constriction means in said metering means providing an orifice for the flow of stock therethrough, sensing means operable to determine a predetermined diminution of flow about said constriction means, and means operable in response to operation of said sensing means to count the number of operations of said sensing means per predetermined time interval.

2. A continuous shive control device comprising a metering tube, means for supplying stock to said metering tube under a constant hydrostatic head, a constriction means adjustably positionable in said tube to provide therein a passage of reduced cross-sectional dimensions, flow metering means sensing the flow through said metering tube, valve means operable to terminate flow of stock into said metering tube and to introduce water therein for flushing accumulated material from said passage in response to sensing of a predetermined reduction in flow by said flow metering means, and means for counting the number of operations of said valve means per predetermined time interval.

3. A continuous shive control device comprising a metering tube, means for supplying stock to said metering tube under a constant hydrostatic head, a constriclll iii)

tion means adjustably positionable in said tube to provide therein a passage of reduced cross-sectional dimensions, flow metering means sensing the fiow through said metering tube, valve means operable to terminate the flow of stock into said metering tube and to introduce water therein for flushing accumulated material from said passage in response to the sensing of a predetermined reduction in flow by said flow metering means, timer means controlling the introduction of water to a predetermined time interval, and means for counting the number of operations of said valve means per predetermined time interval.

4. A continuous shive control device comprising a metering tube, means for supplying stock to said metering tube under a constant hydrostatic head, valve means arranged to selectively introduce said stock to said metering tube and flushing Water into said metering tube, in adjustably positionable plug in said tube providing a constriction for the flow of stock therethrough, flow sensing means positioned to sense the flow of stock into said tube, relay means operable by said sensing means to operate said valve means to terminate introduction of stock and inject flushing water into said metering tube, means operable by said relay means to simultaneously move said plug into a position where said plug provides a lesser constriction to the passage of flushing water than it does to stock passage, a timer means controlling introduction of flushing water to said tube to a predetermined time interval, and counting means for counting the number of operations of said relay means in a predetermined time interval.

5. The device of claim 4 which also includes means for rotating said plug within said metering tube.

6. A continuous shive control device comprising a metering tube, means for supplying stock to said metering tube under a constant hydrostatic head, valve means arranged to selectively introduce said stock to said metering tube and flushing water into said metering tube, an adjustably positionable plug in said tube providing a constriction for the flow of stock therethrough, flow sensing means positioned to sense the flow of stock into said tube, relay means operable by said sensing means to operate said valve means to terminate introduction of stock and inject flushing water into said metering tube, means operable by said relay means to simultaneously move said plug into a position where said plug provides a lesser constriction to the passage of flushing water than it does to stock passage, a first timer means controlling introduction of flushing water to said tube to a predetermined time interval, a counter, means connecting said counter to said relay means, said counter being arranged to count the number of times said relay means is rendered operable to introduce flushing water into said tube, a second timer cycling the operation of said counter to a predetermined time interval, and a recorder-controller receiving the output of said counter for recording the number of counts on said counter during each cycle of operation of said second timer.

7. The device of claim 6 in which said recorder-controller compares the output of said counter with a predetermined value and provides an energizing signal when said output exceeds said predetermined value.

8. The device of claim 6 which also includes means for rotating said plug within said metering tube.

9. The device of claim 6 in which said metering tube has a bell shaped outlet end and said plug is a conically shaped element extending into said bell shaped outlet end.

References Cited by the Examiner UNITED STATES PATENTS 2,391,393 4/1960 Jones 222-148 X RAPHAEL M. LUPO, Primary Examiner.

Claims (1)

1. A CONTINUOUS SHIVE CONTROL DEVICE COMPRISING A METERING MEANS, MEANS FOR SUPPLYING STOCK TO SAID METERING MEANS UNDER A CONSTANT HYDROSTATIC HEAD, A CONSTRICTION MEANS IN SAID METERING MEANS PROVIDING AN ORIFICE FOR THE FLOW OF STOCK THERETHROUGH, SENSING MEANS OPERABLE TO DETERMINE A PREDETERMINED DIMINUATION OF FLOW ABOUT SAID CONSTRICTION MEANS, AND MEANS OPERABLE IN RE-

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