US3358384A

US3358384A - Device for regulating the discharge op a gaseous medium

Info

Publication number: US3358384A
Authority: US
Publication date: 1967-12-19
Anticipated expiration: 1984-12-19

Description

Dec. 19, 1967 R. GUSTAFSSON ET AL 3,358,384

DEVICE FOR REGULATING THE DISCHARGE OF A GASEOUS MEDIUM 3 Sheets-Sheet 1 Filed Aug. 22. 1966 lNVENTORSI RUNE GUSTAFSSON AKE JOHANSSON Dec. 19, 1967 R. GUSTAFSSON ET AL 3,358,384

DEVICE FOR REGULATING THE DISCHARGE OF A GASEOUS MEDIUM Filed Aug. 22, 1966 5 Sheets-Sheet 2 INVENTORS;

RLJNE GUSTAFSSON AKE JOHANSSON Ari [5:

Dec. 19, 1967 Filed Aug. 22, 1966 DEVICE FOR REGULATING THE DISCHARGE OF A GASEOUS MEDIUM 3 Sheets-Sheet 5 F IG.5d.

78 @WHHHHIHHHHHW FIG 6a 5 l ..=g 2 2. [-M' 2/ WM F |G.6b- /3 1 Y I +1 Ff! 2 L INVENTORS:

RUNE GUSTAFSSON AKE JOHANSSON J W W WATTYS.

United States Patent 3,358,384 DEVICE FOR REGULATING THE DISCHARGE OF A GASEOUS MEDIUM Rune Gustafsson, Stockholm, and Ake Johansson, Klinten, Sweden, assignors to Aktiebolaget Svenska Flaktfabriken, Stockholm, Sweden Filed Aug. 22, 1966, Ser. No. 574,053 Claims priority, application Sweden, Aug. 25, 1965, 11,078/ 65 Claims. (Cl. 34-111) The present application is based upon Swedish patent application No. 11,078/ 65 filed Aug. 25, 1965, and is an improvement upon the invention disclosed in Swedish patent specification No. 173,484 and the corresponding United States Patent No. 3,004,348 dated Oct. 17, 1961.

This invention relates to an apparatus adapted for adjusting the discharge of a gaseous medium. The apparatus comprises a distribution conduit with outlet openings in the surface and communicating at one end with a supply chamber, and a control conduit connected to said distribution conduit and also communicating with the supply chamber.

The invention is primarily intended for use in paper machinery such as conventional cylinder driers for blowing hot air against the drying paper web or against the felts which press the paper web against the cylinders. The invention, however, can also be applied in any plant for the treatment of continuous web material wherein the treatment is carried out entirely or partially by blowing a gaseous medium against the running web.

In the manufacture of paper, the paper web is dried by pressing the web against rotating steam-heated castiron cylinders by means of endless textile webs called drier felts. In the case of Wide paper webs it is difiicult to obtain a uniform drying across the entire width of the web. For correcting non-uniformities, it is known to utilize sectioned high-velocity hoods enclosing parts of one or more cylinders, which hoods blow hot air at high speed against selective portions of the paper web. The hoods, however, are expensive and space-consuming.

The non-uniform drying across the width of the web is caused partially by the fact that the threading of the drier forms pockets within the drying section between the drier felt, the paper web, and the drying cylinder. If no special measures are taken, the water vapor evaporating from the paper web and the felt into such pocket will be transported out of the pocket only by diffusion to the ends of the pocket at either side of the drier, because of a'higher partial pressure of the water vapor in the central part of the pocket than at its ends. As the evaporation intensity at the surface of the paper web is proportional among other factors to the difference in the partial pressure between the water vapor in the paper and the water vapor in the ambient air, the intensity of evaporation will be the lowest in the central part of the web. This variation in intensity will not be symmetrical with respect to the central part, because usually the end of the pocket at one side of the machine is more closed than the end at the other side due to the fact that the paper machine conventionally has a non-symmetrical stand.

As evident from the above, the drying of paper would be improved by a simple means for correcting variations in the moisture content in the width direction of the paper web as well as by a means for preventing the variations caused by non-uniform Water vapor pressure in the pockets. The means may be in the form of conduits ex tending in the pockets in parallel with the paper web and transverse thereto, which conduits along their length are provided with openings for blowing a gaseous medium, preferably hot air, against the paper web. In the sections of the paper web thus exposed to the air stream, a greater heat transfer coefiicient between paper and air will be obtained than in the unexposed sections and as a result thereof, the evaporation intensity increases locally in the sections exposed to the air jets. After its contact with the paper web, the air flows out of the pocket at its ends and takes along the evaporated water vapor, which thereby is transported out of the pocket more rapidly than by mere diffusion and thus will not build up a high partial pressure in the central part of the pocket. A conduit of the aforesaid type is disclosed in Swedish patent specification 173,484 and corresponding US. patent specification 3,004,- 348. However, this conduit, in certain installations, is insufliciently adjustable.

The present invention, therefore, has as its object to provide a distribution conduit having such small dimensions that its placement in the pockets of a paper machine does not jeopardize the threading and feed of the paper web or the operation of the paper machine, but of such a good adjustability that it allows the correction of nonuniformities in the moisture content and operation with air amounts chosen such that a suitable discharge speed for air and water vapor is obtained. The last-mentioned feature is realized in the apparatus according to the invention since it operates with small air amounts blown out at high speed at the places where correction is desired.

More specifically, the present invention provides apparatus wherein the distribution conduit is partitioned transversely into longitudinally-aligned parts or spaces and has improved means for regulating the total flow of gaseous medium from said conduit parts or spaces so as to cause flow totally from one part, totally from the other part, or proportioned between the parts.

More specifically, the present invention provides a supply chamber in direct communication with one part of the distribution conduit, and a control conduit positioned coaxially within said distribution condut for conducting the gaseous medium from the supply chamber to the other part of the distribution conduit, said control conduit being displaceable to serve as a proportioning valve for proportioning the flow between the respective parts of the distribution conduit.

In accordance with another feature of the invention, the distribution conduit is provided with a series of apertures in the respective parts thereof, and said control conduit is provided with shielding plates to limit the flow through said apertures in the respective parts.

Preferably, the control conduit is rotatably mounted within said distribution conduit and is rotatable to vary the distribution of fiow through said apertures by displacement of the shielding plates with respect thereto.

All of the objects of the invention are more fully set forth hereinafter with reference to the accompanying drawings wherein:

FIG. 1 shows a longitudinal section partially in elevation through an apparatus according to the invention;

FIG. 2 shows a cross section taken on the line 2-2 of FIG. 1;

FIG. 3 is a fragmentary side view of the drying section of a paper machine showing the apparatus placed in a pocket thereof;

FIG. 4 is a cross-section of the paper machine through the same pocket, and

FIGS. Sa-Sd and 6a-6b show the profile of the air flow at different settings of the apparatus.

Referring to FIG. 1, a distribution conduit 1 of circular cross section is provided in its surface with outlet open ings 2. A supply chamber 3 connected to one end of the conduit 1 has a gas inlet 4 adapted for connection to a fan 27 which, as shown in FIG. 4, sucks air from the atmosphere through a heater 28 and a filter 29. Within the distribution conduit 1 and concentric therewith, a control conduit 5 of circular cross section is mounted for rotational and axial movement in the distribution conduit 1. To this end, the conduit 5 is supported by balls 6 placed inball holders 6:: within the distribution conduit 1. At one end, the conduit 5 opens into the supply chamber 3 through a conical inlet 7 which reduces the flow losses, and is provided with an outer flange 8 spaced inwardly from the inlet 7. In the left-hand limit position of the control conduit 5, the conical inlet 7 abuts against one wall 3a ofthe supply chamber 3 and blocks communication between the supply chamber and the interior of the control conduit 5. In the right-hand limit position of the control conduit 5, the flange 8 abuts against the opening of the distribution conduit 1 and blocks thereby the direct communication between the supply chamber 3 and the distribution conduit 1.

7 At the end of the control conduit 5 facing away from the supply chamber, an end wall 9 serves as a mounting for a rod 10 which together with a first lever 11 forms an adjustment member for the axial displacement of the control conduit 5. Said rod 10 further is provided with a second lever 12 by means of which the control conduit 5 can be rotated. Close to the wall 9, the surface of the control conduit 5 is provided with openings 13 through which the control conduit 5 communicates with the distribution conduit 1. For preventing flow losses, said openings can be provided with guide vanes 14. The openings 13 may be replaced by openings in the wall 9, in which case the wall may be replaced by cross arms. Also, the lever 11 may be replaced by a threaded wheel in order to facilitate the accurate setting of the desired axial position of the control conduit 5.

The space 15 between the distribution conduit 1 and the control conduit 5 is divided by a wall 16 into two parts 15a and 15b of substantially equal size, the said wall 16 being mounted on the control conduit 5 and sealing against the distribution conduit 1 by a sealing element 16a of resilient material. The wall, instead of being mounted on the control conduit 5, may be mounted on the distribution conduit 1, without departing from the inventive idea. When the control channel is moved to its left-hand limit position in FIG. 1 and a gaseous medium is supplied via the gas inlet 4 to the supply chamber. 3, the gas will flow into the space 15a and out therefrom through the openings 2 in the surface of the distribution conduit. The flow pattern formed thereby resembles substantially the pattern shown in FIG. 5a. The arrows correspond as to speed and direction of the gas discharged through the openings 2. Due to the fact that the conical inlet 7 of the control conduit 5 abuts against the wall 3a of the pressure chamber 3 and shuts off the communication between the inlet chamber and the space 15b, no gas will flow to the said space.

When the control conduit 5 is moved to its right-hand limit position, the gas from the pressure chamber will flow into the control conduit 5, through the same, and, via the openings 13, into the space 15b. The flow pattern formed corresponds to that shown in FIG. 5b. The communication between the pressure chamber and the space 15a is shut off since the outer flange 8 of the control conduit 5 abuts against the end of the conduit 1 and closes the opening between the distribution conduit 1 and the pressure chamber 3. By moving the control conduit 5 from its right-hand limit position somewhat to the left, a flow pattern according to FIG. 5a will be formed. Upon the continued movement of the control channel to the left, this pattern gradually transforms into the pattern according to FIG. 5a. In the central position, a pattern according to FIG. 501 is obtained. Thus, the left-hand end of the control conduit serves as a valve to proportion the flow between the spaces 15a and 15b. v

As evident from FIGS. 5a'5d, the apparatus provides great possibilities of varying the flow pattern and thereby thesheat transfer coeflicient between the gas .and a paper web located at a suitable distance from the openings 2 of the distribution conduit 1. The heat transfer coefiicient is proportional to the diffusion transfer coefficient between the web and the ambient gas and the diffusion transfer coeflicient is proportional to the evaporation intensity when the difierence in the partial pressure between the surface of the paper web and the ambient gas -is constant. By changing the flow pattern, thus, the intensity of the local evaporation can be affected.

In FIG. 1, furthermore, a plurality of shielding plates 17 are shown which, as shown in FIG. 2, are mounted by rods 18 in the control conduit 5 and are pressed against the inner surface of the distribution conduit 1 by springs 19. By rotating the control conduit 5, the shielding plates 17 can be caused to entirely or partially cover the openings 2 in the distribution conduit 1 and thereby prevent gas from flowing out through the outlet openings.

The shielding plates 17 can be arranged such in relation to the openings 2, that the flow pattern can be varied between certain desired limits. The openings 2 ma for example as shown, be aligned in two straight lines and the shielding plates 17 may have sloped edges such that, upon rotation of the control conduit 5, they gradually cover the openings 2 in the opposite spaces 15a and 15b in sequence symmetrically with respect to the wall 16 starting with the openings located farthest away from the wall 16. A corresponding flow pattern with the control conduit 5 in a central axial position is shown in FIG. 6a. Upon moving the control conduit 5 somewhat to the left, the fiow pattern according to FIG. 6b is obtained. Due to the fact that both the shape of the shielding plates 17 and their location relative one another as well as in relation to the openings 2 can be chosen freely, there are great number of possibilities for obtaining a suitable number of flow patterns. The afore-described arrangement wherein the openings most remote from the center of the paper web are covered first, can be assumed to be the most suitable in paper machines, because in many cases, the edges of the web dry more rapidly'than the central portion of the web, if no special steps are taken. The moisture content variation caused thereby usually is somewhat unsymmetrical in relation to the center of the web, for reasons as stated above. The apparatus described is well adapted as a means for eliminating this variation. Preferably, as shown in FIGS. 3 and 4, the apparatus is placed in the drying section of a paper machine within the pocket formed between the drier felt 24 for the upper cylinders 22a, the two runs of the paper Web 23, and the exposed part of the lower drying cylinder 2212. In this case, the assembly suitably can be utilized as a mounting for a doctor blade 21. In such cases the stub shafts 20 of the apparatus are supported in mountings 25 secured on the machine frame 26.

While a particular embodiment of the invention has been herein illustrated and described, it is not intended to limit the invention to such disclosure, but changes and modifications may be made therein and thereto within the scope of the following claims.

What is claimed is: v

1. In a device for regulating the distributionsand direction of a gaseous'medium being blown against a web, said device consisting of a supply chamber for the gaseous medium, a distribution conduit arranged across .the web and being formed with outlet openings along its length for said medium, said conduit having an inlet opening at one end connected 'tosaid supply chamber, a control conduit extending parallel to said distribution conduit, said control conduit having an inlet opening into said supply chamber at said one end and connected to said distribution conduit at the opposite end to afford flow of gaseous medium into the opposite end of'said distribution conduit, the improvement. wherein said distribution conduit is provided with a partition intermediate its ends to form two separate spaces along the length of the said distribution conduit, one of said spaces communicating With said supply chamber directly through the inlet opening of said distribution conduit and the other of said spaces being connected to said supply chamber through said control conduit, and adjusting means for proportioning the flow of gaseous medium from said supply chamber to the respective spaces, said adjusting means in one limit position afiording total flow into said one space and no flow into said other space, and in the other limit position, affording total flow into said other space and no flow into said one space.

2. Apparatus according to claim 1 wherein said control conduit is disposed interiorly of said distribution conduit, said spaces being formed intermediate said control conduit and said distribution conduit.

3. Apparatus according to claim 1 wherein said control conduit is mounted for axial displacement in said supply chamber between a first limit position in which the inlet of said control conduit is closed and a second limit position wherein said inlet of the distribution conduit is closed, said adjusting means operable to displace said control conduit between said first and second limit positions to thereby proportion the flow from said supply chamber between said two spaces.

4. Apparatus according to claim 3 wherein said control conduit is mounted coaxial within said distribution conduit and projects into said supply chamber at said one end, a flange surrounding the projecting end of said control conduit within said supply chamber operable in the second limit position of said control conduit to close said inlet opening of said distribution conduit, and Wall means in said chamber operable in the first limit position of said control conduit to close the inlet opening of said control conduit.

5. Apparatus according to claim 4 wherein the inlet of said control conduit in said supply chamber is conical.

6. Apparatus according to claim 1 wherein said conduits are of circular cross section and said control conduit is disposed coaxial within said distribution conduit to form said spaces intermediate said conduits.

7. Apparatus according to claim 6 wherein said control conduit is mounted for rotation within said distribution conduit and including shielding plates mounted on said control conduit and bearing against the inner surface of the distribution conduit and operable upon rotation of said distribution conduit to cover said outlet openings.

8. Apparatus according to claim 7 wherein said outlet openings are aligned and said shielding plates upon rotation of said control conduit operate to close said aligned openings in sequence.

9. Apparatus according to claim 8 wherein said shielding plates are constructed and arranged to close the openings in said two spaces symmetrically in sequence starting at the ends of the line most remote from the said wall and progressively covering additional openings upon further rotation of said control conduit whereby the openings adjacent said wall are the last ones to be closed.

10. Apparatus according to claim 7 wherein said outlet openings are arranged in two axial lines in each space, and including two shielding plates in each space having sloped edges such that upon rotation of the control conduit, they close the openings in sequence starting at the ends of the lines most remote from said wall.

References Cited UNITED STATES PATENTS 2,825,979 3/1958 Verwayen et al 34160 X 3,004,348 10/1961 Gustafsson 34-114 3,290,795 12/ 1966 Jarreby 341l5 X FREDERICK L. MATTESON, JR., Primary Examiner. A. D. HERRMANN. Assistant Examiner.

Claims

1. IN A DEVICE FOR REGULATING THE DISTRIBUTION AND DIRECTION OF A GASEOUS MEDIUM BEING BLOWN AGAINST A WEB, SAID DEVICE CONSISTING OF A SUPPLY CHAMBER FOR THE GASEOUS MEDIUM, A DISTRIBUTION CONDUIT ARRANGED ACROSS THE WEB AND BEING FORMED WITH OUTLET OPENINGS ALONG ITS LENGTH FOR SAID MEDIUM, SAID CONDUIT HAVING AN INLET OPENING AT ONE END CONNECTED TO SAID SUPPLY CHAMBER, A CONTROL CONDUIT EXTENDING PARALLEL TO SAID DISTRIBUTION CONDUIT, SAID CONTROL CONDUIT HAVING AN INLET OPENING INTO SAID SUPPLY CHAMBER AT SAID ONE END AND CONNECTED TO SAID DISTRIBUTION CONDUIT AT THE OPPOSITE END TO AFFORD FLOW OF GASEOUS MEDIUM INTO THE OPPOSITE END OF SAID DISTRIBUTION CONDUIT, THE IMPROVEMENT WHEREIN SAID DISTRIBUTION CONDUIT IS PROVIDED WITH A PARTITION INTERMEDIATE ITS ENDS TO FORM TWO SEPARATE SPACES ALONG THE LENGTH OF THE SAID DISTRIBUTION CONDUIT, ONE OF SAID SPACES COMMUNICATING WITH SAID SUPPLY CHAMBER DIRECTLY THROUGH THE INLET OPENING OF SAID DISTRIBUTION CONDUIT AND THE OTHER OF SAID SPACES BEING CONNECTED TO SAID SUPPLY CHAMBER THROUGH SAID CONTROL CONDUIT, AND ADJUSTING MEANS FOR PROPORTIONING THE FLOW OF GASEOUS MEDIUM FROM SAID SUPPLY CHAMBER TO THE RESPECTIVE SPACES, SAID ADJUSTING MEANS IN ONE LIMIT POSITION AFFORDING TOTAL FLOW INTO SAID ONE SPACE AND NO FLOW INTO SAID OTHER SPACE, AND IN THE OTHER LIMIT POSITION, AFFORDING TOTAL FLOW INTO SAID OTHER SPACE AND NO FLOW INTO SAID ONE SPACE.