US1687446A - Flow regulation - Google Patents

Description

Oct. 9, 1928.

I N VEN TOR. yam Q )MM W1 A TTORNEYS.

Y B K v A m: l mu J I m. .F J W E Patented Oct. 9,

PATENT OFFICE.

UNITE!) STATES JAMES A. HEDGCOGK, OF DAYTON, OHIO, ASSIGNOR TO THE MANAGEMENT ENGI- NEERING AND DEVELOPMENT COMPANY, OF DAYTON, OHIO, f1 CORPORATION OF OHIO.

FLOW REGULATION.

Application filed January 29, 1927. Serial No. 164,448.

In the manufacture of paper from fibrous materials, it is the general practice to suspend the fibrous material in water to produce a pulp or paper stock, the relative proportions 6 of fibrous material to water being controlled to give a consistency which is such that the pulp or paper stock may be pumped or flowed through pipes or troughs to the stu if or stock chests, the head boxes, or the like. Herein- 10 after such suspensions of fibrous material in water will, for purposes of description, be referred to as fibrous stock, and this term is intended to include the various forms of fibrous suspensions, used in paper making.

In general, there is a consistency of fibrous stock which is most desirable for given operating conditions and desired results. and this consistency having been determined it IS desirable that there be no material variations therefrom. The consistency may be roughly controlled by taking samples from time to time and varying the consistency or dilution from time to time; but it is desired to secure continuous control.

Heretofore quite satisfactory means has been provided for controlling the consistency of such stocks as are known as thick stock. by which is meant fibrous stock containing from 3% of dry fiber upwards. But there has been no method or apparatus for successfully controlling or indicating with respect to fibrous stocks of'lower consistency, so that control might be effected, of the consistency of the stock when the percentage of fibrous material is materially below 3%. Especially is this so in the case of thin stock in which the consistency is in the neighborhood of 1% or less.

One of the principal objects of this invention is to provide a method of controlling the consistency of fibrous stock, which method is applicable also to thin stock, and is more accurate than methods heretofore used.

Another object of this invention is to provide apparatus for carrying out the above method.

Other objects and advantages of this invention will be apparent from the following description when taken in connection with the accompanying drawing.

In the drawing in which like characters of reference designate like parts throughout the several views thereof;

Fig. 1 is an isometric view of apparatus for practising the invention; and

Fig. 2 is an elevational view of a modified form of resistance element adapted for use with the apparatus of Fig. 1.

It has been heretofore attempted to effect control of the consistency of fibrous stocks on the basis of variations in flow through an orifice accompanying variations in the proportionate quantity of fibrous material in sus-' tions may be magnified into a satisfactorily 1 working magnitude by flowing the thin stock through a suitable flow passagesuch for example as a pipe of moderate diameter, and in-,

terposing a resistance to the flow of the stock through the pipe. n

I have discovered that when a pressure head is impressed upon the fibrous stock passing through such a flow pipe or passage. with suitable resistance to flow, the residual head existing at a predetermined point along said flow passage is proportional to-the consistency of the stock. Furthermore. it has been discovered that this residual head varies quite markedly for small changes in the consistency of the stock, this variation. in residual head being sufficient for an accurate control of the consistency of the stock by means of pressure actuated mechanism. In View of the fact that small differences in stock consistency produce appreciable differences in residual head, a thin stock can be readily controlled; in fact, a stock having a consistency considerably less than 1% lends itself readily to this control.

Referring to the drawing, in which there is illustrated a preferred embodiment of apparatus designed for carrying out the method of this invention, there is disclosed in Fig. 1 a conventional pulp stock trough 10 through which a continuous stream of fibrous stock,

with a 4-inch diameter of the coils.

from any suitable source (not shown), is

- adapted to flow to subsequent treating apparatus (not shown).

The stock received at the inlet end of the trough may have any suitable practicable consistency range, roughly controlled within reasonable limits with respect to the actual definite consistency desired,this being usual paper mill practice, and means for effecting this rough control being therefore notshown. Associated with the trough is a dilution pipe 14 which is arranged to discharge additional dilution water into thestock passing through the trough. The amount of additional dilution water added to the stock from the pipe 14 is controlled, in accordance with the consistency of the resulting diluted stock to main tain such diluted consistency as desired.

Preferably this control apparatus is constructed to operate upon only a portion of the stock passing through the trough 10, a small portion of this stock being withdrawn from the main portion thereof for this purpose. A centrifugal pump 20 has its suction side connected by a pipe 21 to the passage within the trough 10, beyond the point of discharge of pipe 14.

The pipe 21 extends within the trough 10 transversely thereof and is provided with a plurality of perforations 22 whereby a representative portion of the stock passing through the trough is obtained. The pump 20 is driven by a constant speed motor 23, of any suitable conventional type. The outlet of the pump is connected to a flow pipe 30, of considerable length, and is preferably of comparatively small diameter. A coil 31, which gives added resistance to the flow of the stock, is inserted within the pipe 30. In actual practice satisfactory results have been secured with 10 feet of %-inch pipe coiled With such apparatus, the residual head is found to be proportional to the consistency of the stock passing through the flow passage. \Vhen the consistency of the stock varies it is found that the residual head likewise varies quite markedly, and the use of the long flow assa e, especially with a tortuous coil or the like t erein, multiplies this variation in resistance,-and correspondingly varies the residual head. A resistance element such as that shown in Fig. 2, comprising a pipe 35 bent to form a plurality of reverse bends, may be used in place of the coil if desired. The constructionof the resistance element in any case is suchthat a substantial portion of the pressure head of the flowing stock is converted into lost friction head. The result is that at any predetermined point along the line of How there exists a residual pressure, which residual pressure varies with the con sistency of the stock.

This variation in residual head is utilized according to this invention to control the rate of addition of dilution water added through the pipe 14 to the stock. For this purpose, a suitable pressure element 40 is positioned to be responsive to this'residual head. Satisfactory results are obtained-by connecting this'pressure element to the flow passage at a point beyond the resistance element 31. The pressure element 40 is shown as a bellows or sylphon 41, the interior of which is connected to the flow passage and is therefore responsive to the residual head existing therein at the point of connection.

This pressure element is designed to actuate a suitable valve indicated generally at 45 positioned within the dilution ipe 14 to control the flow therethrough. is shown, the valve is a balanced valve provided with a stem 46 cooperatively connected to one arm 47 of an actuating lever pivoted at- 48, the other arm 49 of which is pivotally connected at 50 to an extension 51 of the sylphon 41. A spring 55 is provided to effect closing movement of the valve.

In order to vary the consistency of the thin stock being controlled, a sliding weight 60 is provided on one arm of the lever, a number of notches 61 being formed in the lever to accurately position the weight 60. Thus the consistency of the stock may be controlled over a wide range, and for any one setting of the weight 60 the consistency is maintained substantially constant.

Infoperation, stock of generally controlled consistency is flowed through the trough 10 and.is diluted to the desired consistency with additional water introduced through pipe 14. A continuous portion of the diluted stock is withdrawn by the pump 20, which operates to force the stock under controlled head into and through the flow passage and resistance element 31, this resulting in a residual head being eflective at the pressure element 40.

Ordinarily the desired controlled head may be obtained by using a centrifugal pump and operating it at a substantially constant speed within its normal operating range. As long as the consistency of the stock remains substantially constant, this residual head likewise remains constant. If the consistency of the stock should vary, the residual head effective at the pressure element 40 also is varied, causing a movement of the pressure element, thereby rocking the lever arm to further operate the valve 45 in the. dilution pipe 14 to adjust the supply of dilution water, to bring the stock to the desired predetermined consistency. The effect is that fluctuation in the stock consistency results in the actuation of the control apparatus to control the positioning of the valve 45 whereby the consistency of the stock is maintained substantially constant.

The withdrawn portion of the stock passed through the control apparatus is returned to the trough. A pressure-indicating gauge 01' a suitable pressure-recording instrument may be connected 1n the pipe 30, as illustrated at 65, if desired to indicate or record the consistency. lVhile mechanical connections for actuating the valve 45 have been illustrated herein, it is to be understood that the pressure element 40 can be constructed to operate suitable electrical or other mechanism for actuating this valve.

While the method herein described, and the forms of apparatus for carrying this method and that changes may be made therein with out departing from the scope of the invention which is defined in the appended claims.

\Vhat is claimed is:

1. In the preparation of fibrous stock of thin consistency, the method which comprises diluting said stock to a predetermiiied consistency range, adding an additional supply of dilution water to said stock, impressing a predetermined head upon said additionally diluted stock within a flow passage, and controlling the supply of additional dilution water in accordance with the residual head at a predetermined point in said flow passage.

2. In the preparation of fibrous stock of thin consistency, the method which comprises diluting said stock to a predetermined range of thin consistency, varying the relative proportion of dilution water in the stock to secure a predetermined substantially constant consistency by introducing controlled quantities of additional dilution water, and controlling the quantity of such additional dilu- I tion water by impressing a controlled head upon the resulting additionally diluted stock while said resulting stock is passing through a flow passage, in accordance with the resid ual head at a predetermined point in said flow passage.

3. In the preparation of fibrous stocks of thin consistency, the method which comprises diluting said stock to a predetermined consistency range, adding additional controlled quantities ofdilution water to said previous,

ly diluted stock, withdrawing a portion of the resulting diluted stock, impressing a predetermined head upon said withdrawn portion of additionally diluted stock within a flow passage. and controlling the supply of additional dilution water in accordance with the residual head at a predetern'iined point in said flow passage.

4. Apparatus of the character described, comprising means for causing a continuous flow of fibrous stock or the like, a dilution pipe for adding diluting liquid to said flowing stream of stock, a valve within said pipe for controlling the flow therethrough, means beyond said dilution pipe for withdrawing a portion of said diluted stock from the flowing stream, and control means responsive to the consistency of the withdrawn portion of said diluted stock for controlling the positioning of said valve, said control means including a flow passage, means for impressing a controlled head upon'said withdrawn por tion of stock within said flow passage, and pressure-actuated means responsive to the residual head at a predetermined point in said flow passage.

5. Apparatus of the character described, comprising means for causing a continuous flow of fibrous stock or the like, a dilution pipe for adding diluting liquid to said flowing stream of stock, a valve within said pipe for controlling the flow therethrough, means beyond said dilution pipe for withdrawing a portion of said diluted stock from the flowing stream, and control means responsive to the consistency of the withdrawn portion of said diluted stock for automatically controlling the positioning of said valve to thereby maintain the consistency of said flowing stream of diluted stock substantially constant, said control means including a power driven pump having its suction side connected with said diluted stock withdrawal means, a flow passage connected to the pressure side of said pump, and pressure-actuated means responsive to the residual head at a prede: termined point in said flow passage.

6. Apparatus of the character described, comprising means for causing a continuous flow of fibrous stock or the like, a dilution pipe for adding diluting liquid to said flowing stream of stock, avalve within said pipe for controllingthe flow therethrough, means beyond said dilution pipe for withdrawing a portion of said diluted stock from the flowing stream and control means responsive to the consistency of the Withdrawn portion of said diluted stock for automatically controlling the positioning of said valve to thereby means, a flow passage of substantial resistance to fluid flow connected to the pressure side of said pump, and pressure-actuated means responsive to the residual head at a predetermined point in said flow passage.

7. Apparatus of the character described, comprising means for causing a continuous flow of fibrous stock or the like, a dilution pipe for adding diluting liquid to said flowing stream of stock, a valve within said pipe for controlling the flow therethrough, means beyond said dilution pipe for withdrawing a portion of said diluted stock from the flowing stream, and control means responsive to the consistency of the withdrawn POItIOH of said diluted stock for automatically controlling the positioning of said valve to thereby maintain the consistency of said flowing stream of diluted stock substantially constant, said control means including a power driven pump having its suction side connected with said diluted stock withdrawal means, a resistance element connected to the pressure side of said pump, and a pressure element associated with said valve and responsive to variations in residual'head existing beyond said resistance element.

8. In apparatus for controlling the consistency of thin fibrous stock or the like, a supply of fibrous stock, a pump, said pump having the suction side thereof connected to I said source of fibrous stock, a discharge pipe on the pressure side of said pump, resistance means Within said discharge pipe, and a pressure element connected within said discharge pipe beyond said resistance means and responsive to the residual head existing therein at its point of connection.

9. In apparatus for controlling the consistency of fibrous stock or the like, a supply of fibrous stock, a centrifugal pump having its suction side connected to said supply of fibrous stock, a discharge pipe connected to the delivery side of said pump, means for driving said pump for impressing a c0ntrolled head on the stock delivered to said discharge pipe, and a pressure element connected within said discharge pipe and constructed to be actuated by variations in residual pressure existing at its point of connection.

10. Apparatus of the character described, comprising a supply of fibrous stock, a dilution pipe adapted to introduce a dilution liquid into said fibrous stock, a valve within said pipe, a centrifugal pump having its suction side connected to said supply of fibrous stock, means for driving said pump at substantially co stant speed, a discharge pipe connected to tli'edelivery side of said pump, a pressure element connected within said discharge pipe and adapted to be actuated by variations in residual head therein. and means interconnecting said valve and said pressure element whereby said valve is automatically positioned in accordance with the residual head effective on said pressure element.

11. In the preparation of fibrous stock of controlled consistency, the method which comprises impressing a predetermined head upon fibrous stock within a flow passage, and

= controlling the supply of dilution liquid to the fibrous stock in accordance with the residual head effective at a predetermined point in the fioW passage.

12. In the preparation of fibrous stock of controlled consistency, the method which comprises impressing a predetermined pressure head upon fibrous stock'within a flow passage, consuming a substantial portion of said head in resistance loss by flow through the passage, and controlling the supply of dilution liquid to the fibrous stock in accordance with the residual head effective at a predetermined point in said flow passag after loss of the resistance head.

13. In apparatus of the character described-for controlling. the consistency of fibrous stock, a flow passage to which fibrous stock is supplied, means forimpressing a predetermined head upon the stock within said passage, a dilution liquid supply means for the fibrous stock, and means responsive to the residual head effective at a predetermined point in said flow passage for controlling said dilution liquid supply means.

14. In apparatus of the character described for controlling the consistency of fibrous stock, a flow passage, means for causing a fiow of fibrous stock through said flow passage, said flow passage having a high resistance to flow therethr'ough to produce a substantial resistance loss upon fiow of thin fibrous stock of less than 3% consistency through said passage, dilution means for said stock, and means responsive to the consistency of the stock passed through said flow passage for controlling said dilution means to maintain the consistency of the stock substantially constant.

15. In apparatus of the character described for controlling the consistency of fibrous stock, a flow passage, means for causing a flow of fibrous stock at high velocity through said flow passage, the velocity of the stock being coordinated with the resistance to flow throughthe passage to produce a substantial friction loss upon flow of thin fibrous stock of less than 3% consistency through said passage, dilution means for said stock, and means responsive to the consistency of the stock passed through said flow passage for controlling said dilution means to maintain the consistency of the stock substantially constant. i i

In testimony whereof I hereto aifix'my signature.

JAMES A. I-IEDGOOCK.

no I

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