US1671493A

US1671493A - Dryness controller

Info

Publication number: US1671493A
Application number: US27670A
Authority: US
Inventors: Stephen A Staege
Original assignee: Westinghouse Electric and Manufacturing Co
Current assignee: CBS Corp
Priority date: 1925-05-04
Filing date: 1925-05-04
Publication date: 1928-05-29
Anticipated expiration: 1945-05-29

Description

May 29, 1928.

4 S. A. STAEGE DRYNESS CONTROLLER Filed May 4, 1925 l /ll INVENTOR Jepen A .Saeqe WITNEssEs .QQDW

ATTORNEY Burgaud. May-n.29, '1928. i f

"PATENT oFFlcE..

amm "aisraaeaifor- Premaman, rENNsYLvaNrA, AssIeNon 'ro Waerme#v acusa.' ELEcrmc-a MANUFACTURING COMPANY, .a ooaroaATIoN' orrENNsn- VARIA..

.v l f DRYNESS CONTROLLER.

Application med May 4, 1925. Serial No. 27,670.

M invention relates to dryers and particu arly to dryness controllers.

One object of my invention is4 to provide a relativel simple .and inexpensive means for contro ling the dryness of material in a dryer installation.

In racticing my invention, I provide a main eating means for drying a web of initially-wet material, an auxiliary heating means located in heat-interchanging relation to the leaving web, and a thermal means also located in heat-interchanging relation to the leavin web and effective to control the energizatlon of the main heating means.

In the single sheet of drawings:

Figure 1 is a view, in vertical ongitndmal section, of a system embodying my 1nvention, and, n

Fig. 2 is a schematic dla ram of connections employed with the ryer illustrated in Fig. 1.

A dryer casing, designated byn the nu- :neral 11, com rises a heat-insulating casing of any suitab e or desired construction that is of sullicient width, in lateral section, to

permit of moving therethrough aweb 12 of initially-wet material, such as paper. The dryer casing 11 is adapted to be located alljacent to the wet end of a paper-makl g machine. As the dryer and system lembodying my invention maybe employed with any type of paper machine, it is not thought necessary to illustrate or further describe this part of the mechanism.

Means for moving the initially-wet web of material 12 through the casing 11 comprises a plurality of endless wire belts 13, 14, 15 and 16 that are supported, at then' respective ends, by rollers 14 and 15'.. All of the rollers 14n and 15 are identical in construction and are supported by suitable bearing means (not shown) that may be supported by the side walls of the casing 11 or by frame work of structural steel that is built up insidev of the casing 11.

Smaller roller members 16a are provided to support the upper portions of each of the endless belts 13 to 16, inclusive, and one or more lower rollers 17 may be provided to support the lower part of the endless belt 13. The locations of the respective end' rollers 14 and 15* and of the upper rollers 16'- are such that the upper portions of the ,lower cndle belt .and the lower portion of 4ing e the superposed endless belt are located closely together and are supported by the smaller rollers 16.

The rollers and Iendless belts are caused to move in such manner that the web 12 is passed through the casing in a circuitous ath, and, as shown in Fi 1 of the drawmg, the endless web has t ree passes in its movement through the casing 11.` A relatively narrow entering slot 18 is rovided at one end of the casing -11 and a leaving slot 19 is provided at thel proper location to per. mit of the web 12 leaving the casing While I have illustrated the web 12 as moving in an upward path, this is not essential and I may start the web at the upper portion of the casing and cause it to leave at the lower portion thereof, and any desired number of passes through the casing may be used.

' Means for drying the initially-wet web of material comprises a plurality of heating elements 21 that are located between the upper and lower portions of the respective endless wires, with the exception of the uper wire. These heating means may emody a refractory resistor-supporting member 22 and a suitable resistor Wire 23 mounted thereon' and located inproperly spaced relation relatively to, and beneath, t e web of 4material 12.

As the particular construction and method' of support of the .individual electric( heatements 21 constitutes no part of -my invention, no further detailed description thereof is given. It is essential that the heating elements extend laterally for the full width of the web of material and that they be spaced substantially uniformly.

In general, the drying of the initiall -wet web of material is effected by causin "t e resistors 23 to be traversed by a suita le electric current that causes them to operate at a relatively high temperature and to transl fer the largest part of the heat generated therein by direct radiation against not only the web of material but also against the endless belt. The web of material, is, therefore, dried not only by high-temperature radiant heat, but also by heat conducted thereto from the endlesswoven-wire belts.

As the temperature of'theresistor members 23 may be as high as 1200 F., a ve y rapid drymg action is obtained and e water originallyv in therweb of material when it enters the vcasing-is quickly transformed into steam at 212 F. and is then heated to a much higher temperature, which temperature has been found by actual test to be in the neighborhood of 50001?. 'ljhis means that the steam is in a dry and superheated condition and is, therefore, also let.-y

\ fectiveto dry thcwebfofmatcrial.

VAs the casingf's substantially closed and as the dry superheated 'steam is generated within the casing itself, there will be a slight pressure within"`the.casi-ng over that existing in the air immediately surrounding the casing, and an outlet conduit 24 is providedy in a suitableiportion of the casing to permit the dry superheated steam to either flow out of the casing and through the conduit 24 into a suitable receiver for other use, or to permit a suitable suction means being connected to the conduit 24 to ald 1n removing the steam from the interior of the casing 11.

When the wet web of material 12 is a web of paper, such as news print, thc amount of Water in the web when it enters the casing 11 is substantially 70% of the total Weight thereof'and I have found it advisable to so efect the drying operation within the casing that the amount of moisture or Water remaining in they web of paper when it leaves the casing through the leavingv opening 19 is approximately 7% or less.

The leaving web of paper is led to a plurality of calender rolls 25 and 26 that. are effective, to impart afinish to the surface of the paper and it is then led to a suitable reel 27. As the calender rolls and the reel vare old and well known inthe art and constitute no part of my invention, they are illustrated schematically only and will not be further described. f

The heating means 21 are schematically in Fig. 2 of the drawing as being divided into two groups or sets, one set being controlled through a suitable circuit breaker 28 from a

supply circuit

29 and 31. The other set of heating elements 21 is energized through a circuit breaker 32 from the

supply circuit

29 and 31.

Means for-automatically controlling the supply of energy to the one group of heating e ements through the circuit interrupting means 32 in accordance with the dryness of the leaving web of material, comprises an auxiliary heating element 33 and a thor- -mostatic element 34 suitably located in a heat-insulated, open-bottom casing 35 that is located closely adjacent to the main casingbll and in such position that the leaving We of material will move' past the openY side of the casing 35. A'ny desired method of supporting the heating element 33 and the thermostatic lelement 34 may be em- Y illustratedl ploy'ed and I have illustrated them schematically only as the main consideration is that both the auxiliary heating clement and the ther-mal means be located relatively Aclosely adjacent to the leaving web of paper.

The thermostatic element 34 is provided with an ,adjustable contact member 36 which is connected to one terminal of a source 37 of electicenergy. The other terminal of the source'37 connected to one terminal of an actuating coil 38, the other terminal of which is connected to the fixed end -ot the thermostat 34. vThe circuit-interrupting device 32 has operatively connected thereto a core member 39 that is adapted to he energizcdby the coil 38 when the same is travcrsed by an electric current and to thereby cause the opening of the circuit-interrupting means 32.

If it be assumed that the electric heating elements in the casing 11 have been encrgized a sufficient length of time to bring all of the parts located Withinthe casing 11 lo the normal operating temperature, and itit be further assumed that the web of material .12 has been properly threaded through between the endless belts and that the drying operation has been so effected that the desired dryness of the leaving web is obtained, it may be assumed that the conditions of the electrical circuits are subsi antially as illustrated in Fig. 2 of the drawing, that is, both sets of heating elements 21 are being energized. If now, for any rcason, the temperature .Within the casing should become too high, the immediate result would be that the web of material would be dried to too great an extent and the amount of heat that will be absorbed by the leaving web of material as it moves past the auxiliary heating element 33 in the open auxiliary casing 35 will become less. The thermostat 34 will, therefore, reach a higher temperature than heretofore, not only bccause the temperature of the leaving web of material is higher than it was but also because of the fact that the amount of heat absorbed by the leaving web of material from the auxiliary heating element 33 becomes less and the temperature of the interior of the auxiliary casing 35 rises.

When `the ten'iperal'ure of the thermostatic element 34 has reached a predetermined higher value, the free end thereof will operatively engage the adjustable and normally fixed contact member 36, whereby the actuating coil 38 will be energized and cause a movement of the core member 39 which effects an opening of the circuitinterrupting means 32, whereby one set of the heating elements 21 is deenergized.

AAs soon as the heating elements 21 of one set have cooled suliciently to reduce the ternperature within the casing, the web of material will be dried to a lesserdegree, and the amount of heat that Will be absorbed theref by from thev auxiliary heating element 33 will again increase and this, together with the fact that the temperature of the leaving web is lower than theretofore will cause the the same and reenergize the second set4 of heating elements.

It is evident, of course, that the amount of heat which such a web of material can absorb Will vary inversely With the dryness thereof or Will vary directly with the moisture content thereof. While it is possible to employ the thermostat element 34 without the auxiliary heat 33, I am of the opinion that a morersensitive control device is ob- -tained when the two members are employed simultaneously and when they are so located that they are in heat-interchanging relation stance, be employed with the present type of steam heated drum dryers and it is only necessary that the web of material move ast the primary control means described as eing4 located in the auxiliary casing.

Any desired means for controlling the amount of heat supplied to the dryer, may

be provided,'such as varying the number of electric heating units that are energized, or varying theY voltage supplied'thereto, if electric heating means is employed, or varying the amount of heating fluid or its temperature, if steam is employed in dryer drums, or hot air to move past the web of paper.

Various modifications may be made in the device and system embodying my invention Without departing from the spirit and scope thereof and all such modifications are intended to be covered by the appended claims.

I claim as my invention:

1. In a dryer system, the combination with heating means formdrying an initially Wet web of material, ofv an auxiliary heating means located in heat-interchanging relation to the dried web, and thermal means actuated in accordance with the amount of heat labsorbed by said web from said auxiliary heater for controlling the heating means.

2. In a dryer system, the combination with a dryer casing, and heating means in said casing for drying an initially wet -web of materialpassed therethrough, of an auxiliary open casing located outside of said cas` ing and adjacent to the leaving web of material, an auxiliary heating means in said auxiliary casing in heat-interchangingrelation with the web, and a thermal means in said auxiliary casing actuated in accordance with the amount of heat absorbed by said dried web from said auxiliary heating means for controlling said heating means.

3. In a dryer system, the combination with a main heating means rfor drying an initially wet Web of material, of an auxiliary heating means located in heat, interchanging relation to the dried web, and a thermal means located in heat-interchanging relation to the leaving web and the auxiliary heating means and actuatedin accordance with the heat from the auxiliary heater and with the amount ofv heat absorbed by said web from the auxiliary heating means for controlling the main heating means.

In testimony whereof, I have hereunto subscribed my name this 29th day of April,

STEPHEN A. stanca. y