US1595485A - Velocity fluid vacuum seal, method, and apparatus - Google Patents

Description

Aug. 10 1926. 1,595,485

0. MINTON VELOCITY FLUID VACUUM SEAL, METHOD AND APPARATUS Original Filed 1920 2 Sheets-Sheet 1 VTORNEY Aug. 10 1926. v 1,595,485

0. MINTON VELOCITY FLUID VACUUM SEAL, METHOD AND APPARATUS Ori inal ile 1920 2 Sheets-Shet 2 INVENTOR 1 am am Ad N Patented Aug. 10, 1926.

UNITED STATES OGDEN MINTON, OF GREENWICH, CONNECTICUT.

VELOCITY FLUID VACUUM SEAL, METHOD AND APPARATUS.

Original application filed November 30. 1920, Serial No. 427,436. Divided and this application filed February 4, 1922, Serial No. 534,173. Renewed February 17, 1926.

This application is a division of my copending application Ser. No. 427,436 filed- November 30, 1920, Case L.

My invention relates to the method of treating; materials in a vacuum, and more particularly to the method of protecting, the opening or openings into the vacuum chamber, through which opening or openings the material to be treated is introduced and withdrawn from the chamber.

My invention rel-ates more particularly to a vacuum seal maintained by the application of velocity head, i. e. the difference in pressure between the atmosphere and vacuum being balanced by the velocity head of the scaling medium. Through this seal the material to be treated in the vacuum chamber is passed in any suitable manner.

My invention turther relates more particularly to the method of dryingsheet material, as a continuous web of paper either coming from the wet end of -a paper machine, or from a sizing vat, or from a coloring apparatus, coating machine or printing machine or directly from a roll of wet paper.

My invention further relates to a vacuum apparatus including a vacuum chamber having: passages extending from the said vacuum chamber and open to the atmosphere. These passages are protected by velocity fluid seals which prevent the admission of air into said vacuum chamber as the mate rial to be treated is introduced and withdrawn through said seals.

My present invention further relates to employing a condensable fluid in velocity seals, such as for example steam.

My invention further relates to cmploying passages having restricted areas merging); into prom'e'gsively larger areas between the atmosphere and the interior of the vacuum chamber, forming in etlect Venturi nozzles, through which the fluid of the velocity fluid seals flows.

My invention further relates to collecting the steam and using it in the drying drums or cylinders, or using it to heat the building, or I may condense it, or otherwise dispose of it. I

My invention further relates,to certain steps, and combinations of steps, also to cer tain elements and combinations of elements. whereby the method or processes herein dcsoribed may be carried out, as Well as to certain details of construction, all of which will be more fully hereinafter described in the specification and pointed out in the claims.

I have shown in the drawings, different forms of apparatus which may be used to carry out my improved method, but it is to be distinctly understood that my invention is not to be confined to the particular form of apparatus, shown by way of illus tration.

In the accompanying drawings the same reference numerals refer to similar parts in the several figures.

Fig. 1 is a diagrammatic view of the simplest form of my invention;

Fig. 2 is a diagrammatic View, similar to Fig. 1, showing the web of paper or similar sheet material passing over drying drums or cylinders mounted in the vaccuum cham ber;

Fig. 3 is a steam radiator in which the steam from the velocity seals may be used to heat the building;

Fig.- 4 is a diagrammatic view of metric condenser.

The vacuum chamber A has a maintained therein in any suit-able by connecting the pipe 1 with any suitable exhausting apparatus This vacuum chamber has two passages 22, 2 open to the atmosphere. Through these passages the material to be treated in the vacuum chamber A is introduced and withdrawn. Of course it the passages were left unguarded the vacuum in the vacuum chamber A would be broken.

My invention broadly consists in guarding the passages to the atmosphere by velocity fluid vacuum seals, the velocity of the fluid being sutiiciently high to prevent any air working past the velocity seal into the vacuum chamber.

In my invention suitable material may be introduced into and withdrawn from the vacuum chamber A through my velocity fluid seals 3, 3. It may be treated in any suitable manner within the vacuum chamber. It may be fed through the vacuum chamber continuously or not. I have shown by way of example the material in the form of a continuous web which passes continuously through the vacuum chamber A and the velocity fluid vacuum seals 3, 3. This a baro- YtlClllllll Web may be dried in the vacuum chamber. or coated, impregnated or treated in any other suitable manner, and may be fed into and out of the vacuum chamber in either direction as indicated by the arrows in Fig. 1.

These passages 2, 2 have restricted ar as 4, 4. Connected with these restricted areas are nozzles 5, 5. The area of the passages 2, 2 increases at 6, 6 adjacent the restricted areas 4, 4.

Steam which has no aflinity for or deleterious effect upon the web, or other material treated, is forced into the chambers 7, 7 through the pipe 50 and through the nozzles 5, 5 at sufficient velocity to prevent air passing through the restricted area 4 and getting into the vacuum chamber A. The velocity required will depend on the vacuum maintained in the vacuum chamber. Preferably I employ as near a perfect vacuum as I can maintain, usually about 28 inches of mercury.

The steam passes through the nozzles 5 with comparatively high velocity. As the fluid reaches the portion 6 of comparatively large area its velocity is reduced. The passage 2 with its restricted area l. nozzles 5 and portions of greater area (i is in effect a Venturi type nozzle. The passage 2 is of course wide enough to permit the free passage of the widest web or other material to be passed into and out of the vacuum chamber.

The steam is collected in the chambers 8. 8 and is led off by the pipes 9. 9 either to the steam drying drums or cylinders 10-, 11. 12, 13 and 14, or it may be used to heat the radiators 15 to heat the building. or it may be connected to a vacuum pipe or condenser 16.

My invention is particularly adapted to be used in connection with drying sheet material in the form of paper. though it is to be distinctly understood that it is equally applicable to and covers drying sheet material in the form of textile fabrics. as for example, drying such fabrics after they have been washed or bleached or dyed. or otherwise treated by a liquid of some description.

The wet web of paper 17 coming directly from the wet end of a paper machine, or from a coloring apparatus. coating machine. printing machine. or directly from a roll of wet paper is fed to the vacuum chamber A through the velocity fluid seal 3 at the left of Fig. 1, then heated and dried in the vacuum chamber A and then out through the second velocity fluid seal 3 at the right of Fig. 1.

When a wet web of paper 17 coming from any source, such as that above described, is to be dried. I preferably pass it through the velocity seal at the left of Fig. 2 and into the vacuum chamber A. The web 17 then passes in contact with the heated drying drums or cylinders 10, 11, 12, 13 and 14; where it is completely dried, and then out through the velocity seal at the exit end of the vacuum chamber A.

In this form of my invention the material to be dried is completely protected by the upper guard belt or felt 20, and the lower guard belt or felt 21 as it passes into and out of the vacuum chamber A. The lower guard felt or belt 21, in its passage through the vacuum chamber, cooperates with the drying drums or cylinders 10. 12 and 14 and in contact with the guide rollers 22. 23. 24. 29. 25. 26, 27. 28 and thence out through the velocity seal at the exit end of the vacuum chamber. and around the guide rollers 30, 31. 32 and 33 where it again meets the upper felt or belt 20, and thence again through the vacuum chamber A. 7

The upper felt or belt 20, with the lower belt 21 protects the web of material 17 as it passes through the entrance velocity seal and cooperates with the drying drums or cylinders 10. l1. l3 and 1 1. On the periphery of the drying drum or cylinder 11 it again meets the lower felt or belt 21, so that the web 17. when cooperating with this thying drum or cylinder 14, is again protected by both the upper and lower guard felts or oelts 20 and 21 which continue to protect it until the web of dry paper r other material. passes through the exit velocity seal, hat on the right of Fig. 2.

The upper belt or felt 20, after passing around the drying drum or cylinder 11 cooperates with the guide rollers 35, 36, 37 and 38. After this upper belt or felt 20 passes through the exit velocity seal it cooperates with the guide rollers 39. 40, 41. 4-2, 43 and +4. where it again meets the web 17 and the lower belt or felt 21.

My method possesses many advantages not present in processes heretofore used for many years in the drying of paper.

The evaporation process, which is characteristic of the so-called loft drying of paper, has many fully recognized disadvantages, and yet it is used today and has been in 18C for many years. In this method the wet paper is taken from the paper machine, cut into sheets. hung on poles, carried to the drying room where it is subjected to hot air at about 130 F. for about 48 hours. and when dry. each sheet is separately calendered. Although possessing the advantage of drying at a comparatively low temperature. whereby the moisture is slowly evaporated. loft drying is obviously very inelli- :rent and costly. because it requires many Separate manipulations, is extremely s ow. uses extensive floor space and wastes heat.

The process which is employed in the ordinary paper machine in common use, is likewise subiect to many disadvantages. In such machine, the wet paper as it comes proximately 5.3 pounds gauge pressure, at "which the steam has a temperature of 228 F., giving a difference of temperature (928- 219") of only 16 F. lVith this slight difference of temperature the transfer of heat is extremely slow, and hence it is necessary to employ many drying cylinders, in board machines often one hundred, and in news print machines, forty or more.

Also due to convection and conduction losses, as well as those incident to leaks in the piping system and other inefficiencies, the heat actually required for atmospheric drying of a. ton of wet paper, is very much in excess of the theoretical requirement. The thermal efficiency of atmospheric drying by steam heated cylinders is therefore very low. Furthermore, the steam produced from boiling the water out of the paper. is driven off into the operating room, and although fans and exhausters are employed. at large expense for power and maintenance, the room atmosphere is so constantly saturated with moisture as to rust and ultimately destroy all iron and steel materials, and produces an exceedingly disagreeable and unhealthy atmosphere in which to work. It is well known that the minimum temperature 212, the atmospheric boiling point of water, is positively in iu rious to, and results in oxidizing, the fibres of the paper, the strength of which is vastly improved when the paper is dried at lower temperatures. as in loft drying. This at mospheric drying process requires large ini tial cost for cylinders. felts, and other necessary equipn'icnt, and extensive floor space. and results in the consumption of large amounts of power, and great cost for operation. maintenance and repairs.

In my improved vacuum drying method 1 contemplatemaintaining within the chamber a va uum of about 22%" of mercury. in which 1 water boils at 100 F.. and supplying the drying cylinders with steam at 5.3 pounds gauge pressure, producing a temperature of 228 F. The temperature difference between the temperature of the steam in the cylinders and that of the paper. is therefore, 128 F. in my vacuum method. or 8 times greater (16 F. 8:.1.28' F.) than the temperature difference in atmospheric drying. In my improved method the paper dries approximately 8 times faster than in atmospheric drying. and I require only about oneeighth the number of drying cylinders to dry paper at the same rate of speed. I am able to dry paper with 5 cylinders in the same time required of 40 cylinders drying at atmospheric pressure, resulting in great economics in cost of the machine, floor space and of necessary piping, felts, auxiliary equipment, and particularly in power and maintenance charges.

The thermal efliciency of my vacuum method is very much greater than that of the atmos 'iheric cylinder drying heretofore in universal use for drying paper. Theoretical- 1v. it requires about 5287 pounds of steam to dry one ton of paper at atmospheric pressure. but to compensate for convection and conduction losses, and those due to leaks in the piping system. and other inefficiencies, it K has been shown in practice that about 10.600 pounds are required.

In my method, using a vacuum of about 28", the convection, conduction and piping losses are exceedingly small and the total stream required to dry a ton of paper by my method is approximately 5200 pounds.

It is an ef-ttablished fact that paper dried at low temperatures is much stronger than when it is dried at the high temperatures used in paper machine atmospheric drying. Paper dried in a vacuum of 28", or at a temperature of about 100 F. as in my method, is very much stronger than paper dried at atmospheric pressure, when the steam in the driers is at 228 F. \Vhen paper is dried by my method, therefore, a cheaper finish or stock can be used and still produce a paper equal in strength to atmospheric dried paper, in which a higher grade finish or stock is used. In making newsprint paper, I am able to dispense with a considerable portion of the more expensive sulphite pulp, as this can be replaced with the cheaper ground wood pulp. By my method I also reduce the number of breaks in the web as it passes over the cylinder.

l urthcrmore. in my method there is a great saving of heat (or steam) because the process is carried on in a vacuum chamber which acts on the principle of a thermos bottle, and the steam and vapors driven out of the wet paper are caught in the closed vacuum chamber, and conducted away to the condenser. The operating room is free from steam, humidity and heat, and fans. and exhaustcrs are dispensed with. In the use of my method the apparatus is at all times operating under definite humidity, the control of the drying can be closely standardized. and the moisture content in the paper carefully regulated.

Some of the modern open air dryers are equipped with a blower system by which air, either heated or not, is blown through the dryer section, which will lower the tempera ture at which the water is evaporated from the paper much below 212 F. and may, in some cases. reduce the temperature of evaporation as low as 180 F. or lower.

&

Having pointed out the many advantages of my method and apparatus over those heretofore used. it will be apparent that the use of my invention results in great economy in the initial cost of apparatus and in large savings in cost of operation. maintenance and repairs.

Having thus described this invention in connection with difi'erent illustrative embodiments thereof. to the details of which I do not desire to be limited. what is claimed as new and what is desired to secure by Letters Patent is set forth in the appended claims.

What I claim is:-

1. The method of sealing against the admission of air into a vacuum chamber having openings for the passage of material to be treated in said chamber. consistingv in preventing the admission of air through said openings by causing a condensable medium to flow through said openings against. the pressure of the atmosphere.

2. The method of sealing against the admission of air into a vacuum chamber having openings for the passage of material to be treated in said chamber. consisting in preventing the admission of air through said openings by causing steam to flow through said openings against the pressure of the atmosphere.

3. The method of sealing against the admission of air into a vacuum chamber having openings for the passage of material to be treated in said chamber consisting in preventing the admission of air through said openings by causing steam to flow through said openings against the pressure of the an mosphere and then condensing the steam.

4. The method of sealing against the admission of air into a vacuum chamber having openings for the passage of material to be treated in said chamber. consisting in preventing the admission of air through said openings by causing steam to flow through said openings against the pressure of the atmosphere and then utilizing the steam to heat the vacuum chamber.

5. The method of continuously drying sheet material consisting in feeding it into and out of a vacuum chamber through a condensable medium. and causing said condensable medium to flow against the pressure of the atmosphere and prevent air working into the vacuum chamber, and drying the sheet material in the vacuum chamber.

6. The method of continuously drying sheet material consisting in continuously feeding the sheet material into and out of openings in the vacuum chamber. drying the sheet material in the vacuum chamber, and preventing the admission of air through said openings by causing steam to flow through said openings against the pressure of the atmosphere.

i. The method of sealing against the ad-, mission of air into a vacuum chamber having openings for the passage of material to be treated in said chamber. consisting in preventing the admission of air through said openings by causing a heated condensable medium to flow through said openings against the pressure of the atmosphere.

8. The method of continuously drying a web of wet paper consisting in continuously feeding the web of wet paper into and out of openings in the vacuum chamber, drying the web in the vacuum chamber, and preenting the admission of air through said ioenings by causing steam to flow through said openings against the pressure of the atmosphere.

9. In a vacuum apparatus the combination of a vacuum chamber having one or more openings for the admission and with rirawal of material into and from said vacuum chamber to be treated. and one or nore velocity fluid seals protecting said opening or openings and preventing the admission of air into said vacuum chamber.

10. In a vacuum apparatus the combination of a vacuum chamber having one or more openings for the admission and withdrawal of material into and from said vacuum chamber to be treated, and one or more velocity tluid seals protecting said opening or openings and preventing the admission of air into said vacuum chamber and means to insure that said velocity fluid seals produce an aspirating effect on any air that might be contained in the vacuum chamber.

.1. In a vacuum apparatus the combinaiion of a vacuum chamber having one or more openings for the admission and withirawal of material into and from said vacuum chamber to be treated, and one or more velocity tluid seals protecting said open ng or openings and preventing the admission of air into said vacuum chamber and means to collect and condense the fluid of the seal.

12. In a vacuum apparatus the combination of a vacuum chamber having one or more restricted passages similar to a Venturi nozzle connected with the vacuum chamber and through said restricted passage or passages the material to be treated in the acuum chamber is adapted to pass. and means to supply steam through said reitricted passage or passages at sufiicient velocity to prevent the admission of air into the vacuum chamber.

13. In a vacuum apparatus the combination of a vacuum chamber having one or more openings for the admission and withdrawal of material into and from said vacuum chamber to be treated. and one or more heated velocity fluid seals protecting and opening or openings and preventing the ion admission of air into said vacuum chamber. 14. In a vacuum apparatus the combina tion of a vacuum chamber having one or more openings for the admission and with- 5 drawal of material into and from said vacuum chamber to be treated, and one or more heated velocity fluid seals protecting said opening or openings and preventing the admission of air into said vacuum chamber and means to heat the vacuum chamber by the exhausted heated fluid of the velocity fluid seals.

OGDEN MINTON.

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