US1646515A - Moisture-controlling device - Google Patents

Description

Lcs. Es. WIIHAM JR norm-URE :coNrRoLuNG DEVICE original Filed Fem-17, 1922 3 Sheets-Shea?I 1 oct. 25, 1927. 1,646,515

G, s. wlTHAM, JR MOISTURE CONTROLLING DVICE Original Filed Feb.17. 1922 3 Sheets-Sheet2 Au?. l

SUPPLY Oct 25 1927' ca.l s. WITHANLJR OISTURE CQNTROLLING DEVICE original Filed Feb.17, 1922 s sheets-sheet 3 L Wmwlwll HHHHHHHHMHQHHHUIHMHMMHOHHMuwHw# Patented Oct. 25, 1927.

GEORGE STANFORD WITHAM, JR., OF HUDSON FALLS, NEW.YORK.

' MOISTURE-CONTRQLLING DEVICE.

Application led February 17, 1922, Serial No. 537,328. Renewed April 28, 1927.

My invention is an improvement in moisture controlling devices, and relates particularly to mechanism for controlling the temperature of the dryers in paper making machines, in accordance with the humidity of the paper being dried. In paper making machines the formed web is usually dried by means ot' heated cylinders, and the temperature required for the proper drying is i" arbitrarily determined, in accordance with the grade of paper being made. The regulation of the temperature is controlled by the back tender, who judges the moisture (foutent of the web by the feel of the same, l5 and the amount of steam admitted to the dryer, and the consequent temperature malntained therein is regulated in accordance with his judgment. The moisture content of the web of a selected grade is not a con- "l" stant factor, varyingnin accordance with many conditions, among which may be mentioned atmospheric. Hence, a temperature that will properly dry a'selected grade of paper under certain conditions, may be 1n- 2" sutlicieut, or more than suflicient, under other conditions. In addition the moisture content of the formed web is` not the same throughout its area, portions thereof having a higher moisture content', than other portions. Obviously only a small proportion of the` area of theriveb coming from the dryer can be tested, and the temperature of the dryer, and the final condition of the web will be determined by the condition of a 'i portion which may be abnormally dry or abnormally Wet. Hence. the final condition of the web, as regards the degree of drying is largely dependent on chance.

Since the moisture content of a Web of a selectedgrade is not a constant factor, the

control of the admission of steam to the drying rolls by the temperature of the rollsV does not meet all conditions. In a copending application, Serial No. 531,863, filed January 26, 1922, I provide means for determining and recording the humidity of the web, at any selected point between the wet end of the forming mechanism and the calender rolls, and for simultaneously determining and recording the temperature at such point, thereby to permit the temperature to be regulated in accordance with the humidity, and to attain proper drying. of

any grade of paper, regardless of varying 5" conditions as to humidity.

In the present invention, I. provide other mechanism controlled by the said means, for controlling the admission pf steam to the dryingrolls, and the consequent temperature of the dryer, so thatfsuch. temperature is governed by the condition of the Web as regardsV humidity, the temperature being so regulated that the web is dried to the deu sired degree Whatever its condition.

In the drawings:

Figure 1 is a diagrammaticside View of the dryer of a paper making machine, provided With the improved controlling mechamsm,

Figure 2 is a. diagrammatic view of the controlling mechanism, r v

Figure 3 shows lan alternative arrangement. f

Figure t is a transverse section of one form of tester which may be used,

Figure 5 is an enlarged bottom View of fthe form of tester shown in Figure 4.

Thepresent embodiment of the invention 1s shown 1n connection With a dryer of 'usual construction, including a plurality of' heated cylinders 1, about Which the paper Webpasses, land the cylinders are heated by steam in the usual manner, the steam being supplied from a manifold 2, which is connected to the respective cylinders at their axes, thereby not interfering with the rotation of the cylinders. Exhaust steam is supplied to the manifold from a pipe 4, which is connected to the manifold by inlet pipes 5. A diaphragm operated valve indicated at 6, is interposed in each of the pipes 5, and the valve is 4controlled by fluid under pressure, Which is admitted to the diaphragm chamber above the diaphragm, to close the valve or partially close the same when the temperature rises above a selected mean. The cylinders of the dryers are arranged in series, and each series is supplied from a section of manifold, the manifold being divided into/sections as shown. The sections vof the Vmanifold are connected by valves 7, which may be opened when desired, but under normal conditions, the sections are 'disconnected from each other, and a pipe 5 connects yeach section With the. supply pipe 4. Within a. selected cylinder 'of each series, a. thermostatic element is arranged, which controls the valve 6 in the pipe 5 which supplies the manifold section with exhaust steam. Preferably the section of cylinders remote from the paper machine, that is that set of cylinders adjacent to the calender rolls, is arranged to control an auxiliary supply of live steam. This' steam is supplied by a pipe 8,aiid the supply is controlled by a diaphragm valve 9 interposed in the said pipe. The thermostatic element in A'the last section of cylinders controls not only the valve 6 in the adjacent pipe 5, but controls also the va-lve.9 in the 'auxiliary steam supply pipe. As shown in Figure 1, a pipe 1() from each thermostatic element is connected with a controlling valve 11, and this valve controls the fluid pressure supply to the adjacent valve 6.

Fluid under pressure, usually air, is supplied by a pipe line 12, which has branches 13 leading to the respective valves 11. The

valves 11 are so constructed and arranged,l

that when the temperature in the selected cylinder increases and the fluid of the thermostat expands, the valve 11 will be in oved toward open position, to admit a higher pressure to the valve 6. The valves 6 are so constructed and arranged, that the admission of a higher pressure to the diaphragm chamber will move the \valve toward closed position, reducing or shuttiner ol' the supply of steam, until the. temperature falls to the proper degree. The pipe 14 which leads from the thermostat in the selected cylinder of the last Series is connected to the duplex valve 15, and the valve 15 is so constructed and arranged that it will control the flow ofluid under pressure to the. valve 6 in the adjacent pipe 5, and to the valve 9 of the auxiliary live steam supply. The arrangement of the entire mechanism is such. that a uniform temperature is maintained in each section of the f dryer.

When the temperature falls below a selected degree, the supply of exhaust steam is increased, while when the temperature passes above the selected degree. the supply of exhaust steam is throttled. This construction is shown and described in my prior application, Serial No. 457.304,' filed March 31, 1921, and the arrangement provides for the ymaintenance of a uniform temperature throughout the drying operation, the temperature being set at any'desired degree. In addition the dryer may be operated in such-manner that the temperature will gradually increase from the auf we-t end to the dry end, the temperature being stepped up at each section of the dryer. V--The 'above described arrangement provides for the proper drying of a selected grade of paper, but there is 'no provision or variations in the moisture content of such selected grade, nor for Ivarying atmospheric conditions. Where the moisture content is greater, or less than the estimated content for the grade, or where atmospheric conditions are such that the evaporation is meeste hastened, or lessened, the selected temperatures for the dierent sections for the selected grade of paper must be Varied, if at all, solely in accordance with'the back tend-ersopinion, determined by the lfeel of the paper.

lln my co-pending application, Serial No. 531,863 filed 'January 26, 1922, 1 show'and describe mechanism for indicating and recording the humidity and temperature at a face of the web being dried, and so. arranged that it may be used to test conditions at any point in the area of the web. The said mechanism shown diagrammatically in Figure '2, comprises a wet bulb 16 and a dry bulb 17, the wet bulb being kept constantly moistened by any suitable means, las for instance, a wick 18, dipping into a tank 19.l

having a float controlled supply valve 2O for retaining a constant level of liquid in the tank.v The pipes 21 :trom the dry and wet bulbs are connected to diaphragm chambers 23 and 23a respectively. The diaphragins of the respective chambers are engaged by pointed'screws 24 and 24, which are threaded through elbow levers 25. rlhe outer end of one arm of each lever 25 is pivoted at 26 to a xed bracket 44, and the outer end of the other arm engages a valve stem 28, which cooperates with a valve 29 in casings 30 and 30a, interposed in the supply line 33 of motor fluid for operating a valve 34 which controls the pipe line 12 before mentioned. This valve. 34 is a differentially controlled valve.

labove mentioned, a slight volume `of dry compressed air is passed between the paper web and the tester, to provide a circulation over the wet bulb. In the form of tester shown in Figures 4 and 5, the wet bulb 16 consists 'of a series of tubes arranged side by side in a pan 38. The dry bulb 17 likewiseconsists of a series of tubes arranged as shown in Figure 5. Flexible tubes 8 and 9 are connected to the dry and wet bulbs respectively. The wet bulbs are covered by a plate 39', which extends across 'the pan to a point near the edge thereof most remote from the bulbs. A perforated tube 40 is arranged above the plate 39 near one end thereof. When the apparatus is -in use, the web of material being dried passes along U Diaphragm casings 32 and 32l are arranged on opposite 4passes out through suit-able vents 41.

the top of the pan 38 and gas, for example any desired manner, and at any part of the` compressed air, is supplied through the tube web, and the temperature of the dryer may 40. This gas passes along the web of material to the far edge of the pan 38 and conditions as indicated .by the test require then passes below the plate 39', as indicated more heat, either because of increased huby the arrows. After the air or other gasmidity, or because of lessened'temperature, comes in contact with the bulbs 16 and 17 it. the valve 34 will be movedgtoward open po sition, increasing' the supply of exhaust The wet bulb 1s iniuenced by the amount steam to the dryer, and if the emergency reof evaporation that takes place on its surquires, admitting live steam to the heade face, and the change is a measure of the ,2. lIt will be understood that so long as the amount of moisture in the,tester. The dryer exhaust steam is sullicient to provide the rethe paper moving over the tester the dryer vquisite temperature, thel live steam is not .will be the airat the tester and the more turned into the header 2, the' live steam be- Hence the ing an auxiliary heating means, for use rapid will be the evaporation.

larger the amount of heat extracted from when the exhaust steam does not suffice.

When conditions as to i '-tently, by any suitable mechanism,

continuously, or at regular lntervals,

`means of this mechanism the condition of the wet bulb, the lower the temperature In order to permit the 'device to be adin comparison with the dry bulb. The wetjusted to any desired mean, so that the fluctu-- ter the paper, the more slowly will evaporaations due to humidity and tempera-ture tiontake place at the wet bulb and the less changes above and below such mean, will heat will be extracted. Hence the temperacontrol the device to vary the temperature, ture at the wet bulb willbe correspondingly I provide the mechanism shown in connechigh in comparison with the dry bulb. tion with the pointed screws 24 and 24a in dryness of the papl Figure 2. The said mechanism comprises a web are normal,l that is when the web is bescale 41 arranged adjacent to the screw, and ing suiiciently dried, and not overdried, the a pointer 0r indicator 42 0n the screw, By temperatureof the dryer will be maintained adjusting the screws 24 and 24, which are at \a selected degree suitable for the grade thumb screws, any desired ratio of leveKIqage of paper being dried. Should, however, may be Secured, there be overdrying, the evaporation at the be nicely regulated to suit conditions. 1f-

In Figure 3 an alternative arrangement is.

wet bulb will become more rapid, and the shown, wherein the wet and dry bulb mechatemperature at the wet bulb will fall. The nism controls the, steam supply for the `last diaphragm of the casing 23 shutting' off the motive fluid to the diament, the motor fluid line 45 is controlled phragm chamber 32a, and the difl'erental by a diaphragm valve 46 similar to the valve pressure on the diaphragms in the chambers l 32,an-d this 32 and 32a will move the valve '34 towards duplex valve 47 ,y corresponding to the valire closed position, shutting o the motive fluid 15 of Figure 1. :The duplex valve is conto the valves 6 and 7, and cutting off the nected by pipe lines 48 and 49 with diasupply o@ steam to the dryer, thereby to rephragm valves 50 and 51 corresponding to duce the temperature. If on the other hand theI valves 9 and 6 of Figure 1, and conthe paper is wet', the evaporation at the wet trolling the supply of live and exhaust steam, bulb will be hindered, or lessened, and the. respectively. temperature .will rise, expanding the diaare connected to the air line controlling phragm of the casing 23a, and opening the mechanism, and this mechanism controls the motive fluid line to the diaphragm chamber valve-46, which in turn controls the air line. 32a. Increase of pressure in such chamber The operation is precisely the same a in the will tend to move the valve 34 toward open construction of Figure 1, except t at thel position. The movement of the valve 34 mechanism controls only the :duplex valve. will also beinfluenced by conditions at will contract, section of the dryer only. In this arrange' line is connected only to thev the Referring to Figure 2, it will be seen that The pipes 21 of the tester 38 dry bulb, that-is by changes in temperature suitable pressure gauges 53 .are arranged 'in at the said bulb, and the action of the bulbsJ the pipes 33 and 31, respectively, and that a on thevalve 34 is a joint or diierentialacsuitable easing 52 encloses the controlling tion. The testing mechanism constituted by mechanism for-the motor fluid line. In both the wet and dry bulbs and associated parts, constructions, the valves 15and ,47- are duis lmounted in a support indicated at 38, plex valves, controlling both the exhaust and which is adapted to'be moved. transversely of the web 39,'either continuously, or interonly the exhaust stemn supply. It will be and understood that any vpreferred form of hythe said mechanism is arranged grostat may be used to determine the hnear the calendar rolls indicated at 40. By mility,

c aim:

preferably' the web as regards humidity and .temperay ture may be ascertained, the J:test being. made cylinders or thev like, which conslsts 1n suplin live steam linesy while the valves 11l control or in plying a heating Vmedium to the cylinders and controlling the supply thereof bymeans responsive 'to changes in both the humidity at the face of the paper andthe temperature of the cylinders.

3. The method of drying paper on heated cylinders or the like, Which'consists in supplying a heating medium to all of the cylinders from a common source, controlling the supply thereof to certain of the cylinders by means responsive to the temperature of one of them and to the humidity at the-face of the paper, and independently controlling the supply of heating medium to other cylinders by means responsive to the temperature of one of these other cylinders and to the humidity at the face of the paper. s 4. In dryers for paper and the like, means responsive to the humidity in close proxim1ty tothe face of the Web, for regulating the temperature of thexdryer.

5. In dryers for paper and the like, means controlled by both the humidity and temperature at the face of the paper for regulating the temperature ofthe dryer.

6. IIn dryers for paper and the like, means for heating the dryer; and means controlled by variations in humidity and temperature at the face of the web for increasing the heat with high humidity and low temperature and for decreasing the heat with ity and high temperature.

7. In\dryers for paper and the like, means for supplying heating Huid to the dryer, and means controlled by the temperature and humidity at the face of the web for controlling the supply to increase the same with high humidity and 10W temperature and to decrease the supply with low` humidity and loWphumidi high temperature.

8. In a dryer for paper Vand the like, means for supplying heating gas to the dryer, a valve forl controlling the supply,

and means responsive to the humidity andy temperature at the face of the web for regulating said valve.

9. In dryers for paper and the like, means for supplying a heating gas to the dryer, an auxiliary supply for heating gas, and ine-ans responsive to both the temperature and the humidity in close proximity to the face of the web for regulating the heating gas supplies.

10. In dryers for paper and the like, the

" combination '-With the heating cylinders,

means for supplying steam to the cylinders,

means controlled by the temperature of ya diaphragm valve for supply in accordance with the temperature v and humidityat the face of the web.

11. In dryers for paperand the like, the combination With the drying cylinders, means for supplying exhaust steam to the cylinders, 'an auxiliary live steam supply for the cylinders, means controlled by the temperature of selected cylinders for regulating the steam supply to maintain a selected temperature in the cylinders, and means for varying the supply in accordance with variations in humidity and temperature at the face of the Web. v

12. In dryers for paper and the like, the combination With the heating cylinders, and means for supplying a heating gas thereto, ot' a valve for regulating the supply, fluid yunder pressure operated means controlling the valve, and means controlled by the temperature and humidity at a face of the Web for controlling said fluid pressure operated means.

13. In dryers for paper and the like, the combination With the heating cylinders,the means for supplying heating gas thereto,

controlling the supply, liuid pressure controlled means for operating the Valve, and means controlled by the humidity and temperature at the face of the Web for operating the luid pressure controlling means. i

14. The method of drying material on heated' cylinders and the like, Which comprises supplying a heating medium to the cylinders, directing a confined current of gas into contact with the surface of the material, whereby said gas partakes of the moisture condition of the material, measuring the moisture content of said gas after contact with said material, and controlling the supply of said heating medium in accordance with the moisture content of said gas. 4

15. In dryers for paper and t-he like, means for supplying heating fluid to the dryer, a conductor for gas. having an opening arranged adjacent and adapted to be substantially closed by a portion of'the'surface of said material for subjecting a current of gas passing through said conductor to intimate contact With said material, means y'for conducting gas to said conductor for passage therethrough, humidity responsive means subjected to said current of gas after contact of the same With said material, and mechameans for controlling the -supnlv of sald heating lluid to the dryer.

In testimony whereof I afliX my signature. GEORGE STANFORD WITI-IAM, JR.

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