US2166379A

US2166379A - Drier

Info

Publication number: US2166379A
Application number: US68362A
Authority: US
Inventors: Skagerberg Rutcher
Original assignee: Brown Instr Co
Current assignee: Brown Instruments Co
Priority date: 1936-03-12
Filing date: 1936-03-12
Publication date: 1939-07-18
Anticipated expiration: 1956-07-18

Description

y 939. R. SKAGERBERG 2, 66,379

DRIER Filed March 12, 1936 2 Sheets-Sheet 1 lzazt'iuer' Sifayeherg A M I y 1939- R. SKAGERBERG 2,166,37

DRIER Filed March 12, 1936 2 Sheets-Sheet 2 Butcher Slfagerbery A A M Patented in, 1a, was 2,166,379

UNITED STATES PATENT OFFICE DRIER Butcher Skagerberg,8t.laul.lllnn.,adgnorto The Brown Instrument Company. Philadelphia,

Pa., a corporation of Penmylvanla Application March 12, 1988, Serial No. 68,808

10 Claims. (01. 34-48) This invention relates to drying machines in no accurate control of the hot air for drying general and more particularly to those types of purposes has been provided. drying machines commonly known as continuous I ilnd that by varying the volume or temperadriers such as are used in paper mills, textile ture or both of the air thus applied to paper mills, etc. driers, there is an instantaneous response. In 5 It is common in the art to provide continuous other words, it the v lum r temperature 18 redriers in paper mills with hollow rolls over which duced the drying eflect is immediately reduced the paper web is led to be dried. These rolls are and the paper becomes damp. If the volume or heated to cause the drying action, the heating temperature is increased the paper immediately J medium usually employed being steam. It is debecomes more dry.

sirable in the process of paper making that It is therefore the prime object of this inventhe paper be dried to within close limits of a pretion to provide an automatic control system for determined moisture content. There is a tenda drier wherein the majority of the drying action ency for the paper web to vary in moisture is obtained by the steam drier rolls, wherein the 5 content when it comes off the drier. These varlsmaller portion of the drying action is obtained ations may be caused by variations in the room by the hot a d y g ans, wherein t e drying atmospheric condition, the thickness of the paper effect of the steam drier rolls is maintained subweb entering the drier, the operation of the stantially con tant n wher in the ry n efi ct presses and the condition of the press felts which of the hot all means is varied in accordance with precede the drier, and the nature of the stock var a ons in e moistu e con e o th p p used in making the paper web. web as it eaves the drier rolls.

It has been the practice in the past to attempt It is another object of this invention to provide to control the moisture content of the finished 9' dr utilizing steam rolls and air blasts for paper by controlling the steam applied to the 7 8 -lbe a s fed Over the s em steam drier rolls. Various methods of controlrellerwherein the heat ntent Of he Steam in ling this steam have been employed, some of the steam rolls is maintained substantially conwhich are maintaining constant pressures or temeht f C v n e in a d wherein the yperatures in the steam drier rolls, which presins e e 0f t e is va ed in reeliohee t0 the sures or temperatures are adjusted by the opermoisture content of the substance being dried, ator or which pressures and temperatures are whereby t substance is dried to Dredetercontrolled by suitable detectors responsive to the mined degree regardless of its condition as it moisture content of the paper web as it leaves n rs he drierthe drier. These control systems have their A further Object of this invention i to provide shortcomings due to their particular principles 8 drier embodying stem 1 eans ve w ich of operation. In these systems it is diflicult to the substance to be dried is fed, the heat conmaintain accurate control of the moisture content which and whsequehtly the d y ng action tent since the steam drier rolls must be constructwhich is maintained Substantially t ted of 'a considerable thickness to withstand cen- A f r Object of this invention i pr vide trifugal force and steam pressure, and this thicka drier in which an air blast is directed at or 0 ness retards the transmission of heat to the paper heal the surface 0! the substance t0 be dried. the 40 web. Therefore, when a detector or controller drying eflect the ll being Varied c dcalls for increasing or reducing the drying eflfect mg to "M1095 the moisture content of the there is a considerable lag or loss of time before substance to be driedthe action of the steam is felt again at the deother objects and advantages will become tector or controller. This type of control syss to those skilled in the art upon reference tom, therefore, involving simply the control of to t e accompanying specification claims and drawings in which drawings: the steam valve supplying steam to the steam Fig 81mm] drier rolls is unable to control the moisture con- 0 1 a auc illustration of my tent of the paper web within very close limits. m z g z g ig mgf ggfig g a It has also been the Practice in the Past to drinier drier with my invention applied thereto;

employ hot air as an xilia y mean of ry n Figure 3 is a sectional view taken substantially paper. The use of this hot air provides addion line 3.4 of Figure 2.

tional drying capacity over and above that which Referring now to- Figure 1, l0 designates the 5 is provided by the steam drier rolls. However, paper web coming from conventional press rolls CJI II and II of the forming end of a paper machine. The web 'll passesoveran idler roll it and then over the steam drier roll it of the Yankee drier. From there it passes over idler rolls II, II, I! and I8 to a calendar stack, not shown.

Heating fluid which may take the form of steam is supplied through a pipe 2| under the control of a valve ll to thedrier rolls l4 toheat the roll I and thereby accomplishing a drying action on the paper web II. The valve ll may be operated by a proportioning motor H which may be oi the type shown and described in Patent 1,989,972, issued to Louis L. Cunningham on February 5, 1935. Condensed steam may be drawn from the drier roll II by means of a pipe 23.

Power may be supplied to the proportioning motor 22 by means oi. line wires 2' and 28 leading from some source of power not shown. The proportioning motor 22 may be positioned in any number of a plurality of positions by means of a controller, generally designated at 21. This controller 21 may comprise a bellows II for operating a slider 28 with respect to a potentiometer coil 3., the potentiometer coil 8| being connected by wires Ii and 32 and the slider I. being connected by a wire 33 to the proportioning motor 22. If it be desired to operate the controller 21 in accordance with temperatures in the drier roll I, the bellows 2! may be connected by a suitable capillary 35 to a bulb, not shown, containing a volatile fill and located in the drier roll I l. The arrangement is such that as the steam presure or temperature increases, the slider 29 is moved upwardly with respect to the potentiometer coil 3. to operate the proportioning motor 22 to position the valve 2! towards a closed position. Likewise, a decrease in steam pressure or temperature causes movement of the slider 20 downwardly with respect to the potentiometer coil 30 to operate proportioning motor 22 to move valve 2| towards an open position. In this manner the valve 2| is positioned in accordance with steam pressures or steam temperatures to maintain the heat content of the drier roll I substantially constant and, therefore, the drying effect of the drier roll I is maintained substantially constant. While I have illustrated in this embodiment of the invention the potentiometer slider 28 as being actuated by a temperature responsive device it is to be understood that this slider may be actuated by changes in pressure of the steam if so desired.

In order to cause drying of the paper web II by means of an air blast, I provide on a Yankee drier a hood 3! over the drier roll ll, the hood 31 receiving a supply of heated air from a fan 38 which may be driven by any suitable means, such as a pulley 38. Fan 38 receives air from a radiator or heat exchanger ll. Heating fluid, which may take the form of steam, may be supplied to the radiator I by means of pipes ll. The hood I1 is provided with openings or tuyeres 42 for causing the air forced into the hood 31 to impinge upon the surface of the paper web Ill and thereby cause a further drying action on the paper web ll. Moisture laden air is drawn oil. the paper web i. through a passage 43 by means of a fan 44 which may be driven by any suitable means, such as a pulley ll.

The supply of steam to the heat exchanger or radiator 4| may be controlled by a valve 4 which in turn may be positioned in any number of positions by a proportioning motor 41, which may also tats the form shown and described in the above referred to Cunningham patent. Power issuppliedtotheproportioningmotorflbymeam of line wires 40 and u leading from some source of power, not shown. The proportioning motorllm'aybeconnectedbywiresllsndll to a potentiometer coil." and by a wire II to a slider l4 cooperating with the potentiometer coil II, a three pole double throw switch 41" belnginterposedinthesewiresasshown. The variablepotentiometer is controlled by a controller, generally designated at I, which may be of any type responsive either directly or indirectly to the moisture content oi. the paper web II as it leaves the drier roll H. For purposes of illustration, I have shown this controller II to be of the tension roll type. The slider I4 is carried by a pivoted lever ll pivoted at 51. The lever It carries a roll II which engages the surface oi the paper web II and this roll II is urged in a clockwise direction by means of an adJus-table weight ll. As the moisture content of the paper web ll increases, the paper web ll expands and allows the weight II to move the slider 54 downwardly with respect to the potentiometer coil l8.

, This downward movement causes operation of the proportioning motor 41 to move the valve ll towards an open position to increase the temperature of the air blast impinging the surface oi the paper web II to increase the drying action thereof. As the moisture content of the paper web ll decreases, the paper web ll contracts to operate the slider 54 upwardly with respect to the potentiometer coil 53 against the action of the biasing weight is. This upward movement of the slider 54 causes operation of the proportioning motor 41 to move the valve 46 towards a closed position to decrease the temperature of the air blast impinging the paper web II to decrease the drying action thereof.

From the above it will be seen that I have provided a control system wherein the majority of the drying action is performed by the drier roll II and the drying action of this drier roll I is maintained substantially constant. Any variations in the moisture content of the paper web Ill leaving the drier roll I aifects the moisture responsive controller 55 to control the temperature of the air blast impinging the paper web ii to increase or decrease the drying action thereof to maintain the moisture content of the paper web Ill leaving the drier roll I substan-' tially constant at all times.

In order to control the drying action of the air blast by controlling the volume of air impinging the paper web l0 instead of by controlling the temperature of the air, the speed of the fan may be varied or a volume damper may be provided between the fan 18 and the hood 31. For purposes of illustration, I have shown a volume damper ii for this purpose. This volume damper 6| may be variably positioned by means of a proportioning motor ll' which is, in all respects, similar to the proportioning motor 41. Power may be supplied to the proportioning motor 41' by means of line wires 48' and 4! leading from some source of power, not shown. Proportioning motor 41' may be connected by wires II, I and 52' to switch 41", which when moved to its downward position connects these wires to wires i0, BI and 52 respectively and hence to the potentiometer of the moisture responsive controller '5. The arrangement is such that as the moisture content of the paper web ll leaving the drier roll ll increases, the volume damper I is operated to increase the iiow of air and, likewise, if

the moisture content of the paper web II de- 7 cresseathevolumedamperliisposltionedto thisheatedaircausingadryingactiononthe decrease the flow of drying air. From the foregoing, it should be apparent that the drying effeet of the air may be controlled by varying either its temperature or quantity, and that either the temperature controller or the volume damper may be employed for controlling the drying eilect by moving switch 41" to the desired position. If it be desirable to control both the volume of drying air and the temperature thereof, the proportioning motors l1 and 41' may both be used to accomplish this mode of operation. This may be done by bridging the oppositecontacts of switch 41" or by omitting this switch entirely.

Referring now to Figures 2 and 3, I have shown my invention as applied to a Fourdrinier drier. The paper web leading from the forming end of a paper mill is generally designated at 88 and this paper web is passed over drying rolls 88 and a spring roll 81 to a calender stack 88. The paper web 85 is held against the upper drying roll 88 by means of a felt 88 suitably guided by guide rolls II. The paper web 85 is also held against the lower drying roll 88 by a felt II suitably guided by means'of guide rolls I2.

Heating fluid which may take the form of steam is supplied to a header I4 under the control of a valve I5 which may be positioned by a proportioning motor I8 which also may be of the type shown and described in the above referred to Cunningham patent. Power is supplied to this proportioning motor I8 by means of line wires I1 and I8 leading from some source of power, not shown. Steam is delivered from the header It by means of pipes 19 to each drier roll 88 to perform the drying action.

The proportioning motor 16 may be adjustably positioned by means of a controller, generally designated at 88, and which may comprise a bellows 8| for operating a slider 82 with respect to a potentiometer coil 08. The potentiometer coil 88 and slider 82 are connected to the proportioning motor I8 by

wires

84, 85 and 86 respectively. If it be desired to operate the controller 80 in accordance with steam pressures in the header I4, the bellows 8i may be connected by a pipe 81 to the header It. If it be desired to operate the controller 80 in accordance with the temperature of the drying rolls 66, the bellows 8| may be connected by a capillary tube to a bulb containing a volatile fill and located in any one of the drying rolls 68. The arrangement is such that as the steam pressure or temperature increases, the slider 82 is moved upward with respect to potentiometer coil 83 to operate proporthe felts 59 and II form pockets which intrap moisture laden air which retards materially the drying action on the paper web 55. It is, therefore, not only an object of this portion of the invention to complete the drying of the paper web 85 but also to rid these pockets of moisture laden air. In carrying this out, I provide air ducts 80 extending longitudinally of the Fourdrinier drier. The ducts 80 are provided with tuyeres 8| for injecting heated air into and through the pockets,

paper web 88 and also ridding the pockets oi moisture laden air. Heated air is delivered to the ducts 88 by means of branch duets l2 emanating from a common duct 88 which receives heated air from a fan or blower 88, which may be driven in any suitable manner, such as by a pulley 8|. Heated air is delivered to the fan or blower 88 through a duct 88 from a radiator or heat exchanger 81 which receives a supply of heating iiuid such as steam from pipes 88. The volume of air delivered to the ducts 88, and consequently the drying action of the air blast, may be controlled by varying the speed of the fan 80, by a volume damper, or by means of a damper 88 which, for purposes of illustration, is shown to be a by-pass damper, the by-pass being afforded by a duct I88.

Referring specifically to Figure 3, with the bypass damper 88 in the position shown, substantially-all of the air delivered by the fan is being forced into the pockets of the drier. As the damper 88 is positioned towards the left, the supply-mi heatedair to the pockets is decreased and i101: excess air is delivered into the by-pass duct The by-pass damper 88 may be adiustably positioned by a proportioning motor Illi which receives a supply of power from line wires I02 and I08 leading from some source of power, not shown. It may also be desired to control the drying action of the air blast not only by controlling the volume of air delivered, but also by controlling the temperature of this air. If this mode of operation be desired, the supply of steam to I I05. This controller I88 may comprise a pivoted lever I09 carrying a tension roll IIO and an ad-- justable biasing weight III. The lever I09 may operate sliders I I2 and Ill with respect to potentiometer coils Ill and H5. The potentiometer coil I and its associated slider II2 may be connected by wires I I1, H8 and II! to the proportioning motor I05. In like manner, the potentiometer coil H5 and its associated slider 8 may be connected by wires I20, |2I and I22 to the proportioning motor IOI.

As the moisture content of the paper web 55 leaving the Fourdrinier drier increases, the sliders H8 and 2 are moved downwardly with respect to their potentiometer coils H5 and Ill to operate the proportioning motors IOI and I05 to increase the volume of air being delivered to the pockets and also to increase the temperature thereof which increases the drying action of the air. As the moisture content of the paper web 55 decreases, the sliders H3 and 2 are moved upwardly with respect to the potentiometer coils I I5 and I It to operate the proportioning motors IOI and I05 to decrease the volume of air being delivered to the pockets and to decrease the temperature thereof whereby the drying action of the air blast is decreased.

If it be desired to control only the temperature of the air and not control the volume of the air, the damper 99 and the proportioning motor III may be omitted and, likewise, if it be desired to control only the volume of the air and not the temperature thereof, the proportioning motor Ill may be omitted.

Ii'itbedesiredtoheatonlythat portion otthe air which is delivered to the tuyeres ll, a'heat exchanger or radiator Illa may be placed in the duct ll between the by-pass damper ll and the branch ducts 0!. Heating fluid in the form of steam may be supplied to this heat exchanger lilo by suitable pipes Illa and the supply of steam to the heat exchanger Illa may be controlled in exactly the same manner as the supply of steam to the heat exchanger ll is controlled. This type of installation in some instances may be more economical since heated air is not bypassed by the by-pass damper ll.

From the above it is seen that in this modiflcation, as in the previous modifications, I have provided a means whereby the drying action of the drying rolls is maintained substantially constant and that any variations in moisture content of the paper web leaving the drier are taken care of by means of the air blast, the drying effect of this air blast being controlled in accordance with the moisture content of the paper web. Therefore, an extremely simple and emcient control system is provided whereby the moisture content of the paper web leaving the driers is maintained substantially constant at all times. Also, it is seen that the majority of the drying action, which in this instance is accomplished by the steam drier rolls, is maintained constant and that variations in the moisture content of the paper web are taken care of by only adjusting a smaller portion of the drying action which, in this instance, is the air blast means. By reason of this mode of operation, an extremely sensitive control may be obtained. Further, in the modiflcation of Figures 2 and 3, I have not only provided an accurate control system for controlling the moisture content of the paper web but have also provided a means for ridding the pockets of a Fourdrinier drier of moisture laden air whereby the drying action of the drier is extremely facilitated.

Although for purposes of illustration, I have shown various forms of my invention, other forms thereof may become obvious to those skilled in the art, and, consequently, my invention is to be limited only by the scope of the appended claims and prior art.

I claim as my invention:

1. In a drier of the class described for drying a substance, drying means for accomplishing a major portion of the drying action, control means responsive to the drying properties of said drying means for maintaining the drying action thereof substantially constant, other drying means for completing the drying action, and means responsive to the moisture condition of the substance to vary said other drying means to increase or decrease its drying action.

2. In a device of the class described for drying a substance, steam drying means for accomplishing a portion of the drying action, means responsive to a heating property of the steam for maintaining the drying action thereof substantially constant, air drying means for accomplishing the remainder of the drying action, and means responsive to the moisture in the substance for controlling said air drying means whereby the substance is dried to a predetermined degree regardless of its initial condition;

3. In a drier of the class described having drier roll means over which the substance to be dried is fed for accomplishing the drying action, the combination of air mm means also for accomplishing a drying action, control means responsive to the drying properties of the drier roll means for maintaining the drying action thereof substantially constant, and other control means responsive to the moisture condition of the substance for varying the drying action of the air blast means, both of said control means coactlng to accomplish a drying action for maintaining the anal condition of the substance to be dried substantially constant regardless of its initial condition.

4. In a drier of the class described having steam drier roll means over which the substance to be I dried is fed for accomplishing a drying action,

the combination of control means responsive to a heating property of the heating medium supplying heat to the drier roll means for controlling the supply of steam thereto for maintaining the drying action thereof substantially constant, hot air blast means also for accomplishing a drying action and comprising ducts, fan means and heat exchanger means, and other control means responsive to the moisture content of the substance for controlling the drying action of said air blast means to maintain the final condition of the substance substantially constant.

5. In a drier of the class described having steam roll means over which the substance to be dried is fed for accomplishing a drying action, the combination of control means responsive to a heating property of the steam supplied to said steam roll means for controlling the supply of steam thereto for maintaining the drying action thereof substantially constant, hot air blast means also for accomplishing a drying action and comprising ducts, fan means and heat exchanger means, and other control means responsive to the moisture content of the substance for controlling the heat content of said heat exchanger means whereby the drying action of said hot air blast means is varied to maintain the final condition of the substance substantially constant.

6. In a drier of the class described having steam roll means over which the substance to be dried is fed for accomplishing a drying action, the combination of control means responsive to a heating property of the steam supplied to said steam roll means for controlling the supply of steam thereto for maintaining the drying action thereof substantially constant, hot air blast means also for accomplishing a drying action and comprising ducts, fan means, damper means and heat exchanger means, and other control means responsive to the moisture content of the substance for controlling the operation of said damper means whereby the drying action of said hot air blast means is varied to maintain the final condition of the substance substantially constant.

7. In a drier for removing moisture from a substance, in combination, air blast means for causing a flow of air across the substance being dried to accomplish a drying action, a controller for varying the drying action of said air blast drying means, motor means for positioning said controller, a device responsive to the moisture content of the substance being dried, and means actuated by said device for controlling said motor means in a manner to increase the drying action of said air blast drying means upon an increase in moisture content of the substance being dried,- and to decrease the drying action upon a decrease in moisture content.

8. In a drier for removing moisture from a substance, in combination, air blast means for causing a flow of air across the substance being dried to accomplish a drying action, a controller for varying the rate of air flow across the substance being dried to thereby vary the drying action of the air blast drying means, motor means for positioning said controller, a device responsive to the moisture content of the substance being dried, and means actuated by said device for controlling said motor means in a manner to increase the rate of air flow over the substance being dried upon an increase in moisture content of the substance being dried, and to decrease the rate of air flow upon a decrease in moisture content.

9. In a drier for removing moisture from a substance, in combination, air blast means for causing a flow of air across the substance being dried to accomplish a drying action, means including a controller for varying the temperature of said air blast for thereby varying the drying action of said air blast drying means, motor means for positioning said controller, a device responsive to the moisture content oi the substance being dried, and means actuated by said device for controlling said motor means in a manner to increase the temperature of said air blast upon an increase in moisture content of the substance being dried, and to decrease the air blast temperature upon a decrease in moisture content.

10. In a drier of the class described having steam roll means over which the substance to be dried is fed for accomplishing a drying action, the combination of motor means for controlling the supply of steam to said steam roll means, a variable resistance operatively related to said motor means, means responsive to variations in a heating property of said steam roll means for varying said resistance to control said motor means proportionately to maintain the heat content of said steam roll means constant, air blast means also for accomplishing a drying action, motor means for controlling said air blast means, a variable resistance operatively associated therewith, and detector means responsive to variations in the moisture condition of the substance for varying said resistance to control said motor means proportionately whereby the drying action of said air blast means is varied to maintain the final condition of said substance substantially 4 constant.

BUTCHER SKAGERBERG.