US1595483A - Velocity fluid vacuum seal, method and apparatus - Google Patents

Description

Aug. 10 1926.

1,595,483 0. MINTON VELOCITY FLUID VACUUM SEAL, METHOD AND APPARATUS Original Filed 1920 2 Sheets-Sheet 1 U Q19 Za Q r-1 10 1 ap/ Z \7 NYENTOR AI ORNEY Aug. 10 1926. 1,595,483

o. MINTON VBLOCITY- FLUID VACUUM SEAL, METHOD AND APPARATUS Original Fi led Nov. 50, 1920 2 Sheets-Sheet 2 2 4 'VENTOR BY Q2 fu T ORNEY\ Patented Aug. in, 1926.

UNITEDSTATES PATENT OFFICE.

oenmv iamron, or easnnwrcn, commcrrcun VELOCITY FLUID VACUUM SEAL, METHOD AND APPARATUS.

Original application filed November 30, 1920, Serial No. 427,436. Divided and this application filed January 21, 1922, Serial No. 530,990. 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or openings into the vacuum chamber, through which opening or openings the material to be treated is introduced and withdrawn from the chamber.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 relates 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 sealing medium. Through this seal the material to be treated in the vacuum chamber is passed in any suitable manner.

My invention further relates more particularly to the method of drying sheet material, as a continuous web of paper either coming from the wet end of a paper maing 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.j These passages are protected by velocity fluid seals which prevent the admission of air into said vacuum chamber as the material to be treated is introduced and withdrawn through said seals.

My present invention relates to employing water, or other similar fluid havin an .afiinity for the material being treate as the fluid of the velocity seals.

My invention further relates to employing passages having restricted areas merging into progressively larger areas between the atmosphere and the interiorof the vacuum chamber, forming in eflfect Venturi nozzles, through which the fluid of the velocity fluid seals flows.

My invention further relates to certain steps, and combinations of steps, also to certain elements and combinations of elements, whereby the method or processes herein described may be carried out, as well as to certain details of construction, all of which will be more fully hereinafter described in the vacuum cham 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 illustration.

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

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

Fig. 2 is a vertical detail section on line 2-2 of Fig. 1' v Fig. 3 is a diagrammatic vertical section showing the web of paper or similar sheet material passing over drying drums or cylinders mounted in the vacuum chamber;

Fig. 4 is a detail vertical section of a modification.

The vacuum chamber A has a vacuum maintained therein'in any suitable manner by connecting the pipe 1 with any suitable exhausting apparatus. .This vacuum chamber has two passa es 2, 2 open to the atmosphere. Throug these passages the material to be treated in the vacuum chamber A is introduced and withdrawn. Of course if 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 sufliciently high to prevent any air working 1past the velocity seal into r.

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 web may be dried in the vacuum chamber, or coated, impregnated or treated in any other suitable manner.

' 2, 2 increases at 6, 6 adjacent the restricted areas 4, 4.

Water or similar fluid is forced into the chambers 7, 7 through the pipes 8, 8 and through the nozzles 5, 5at suflicient velocity to prevent air passing through the restricted areas 4, 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 carrmaintain, usually about 28 inches of mercury.

The water passes through the nozzle 5 with comparatively high velocity. As the water reaches the portion 6 of comparative- 1y large area its 'velocityis reduced. The passage 2 with its restricted area 4, nozzle 5 and portions of greater area 6 1s 1n eflect a venturi type nozzle. The passa e 2 1s of course wide enough to perm1t t e free passage of the Web or other mater1al to be passed into and out of the vacuum chamber A.

My invention is particularly adapted to be used in connection with drying sheet material in the form of paper, though 1t 1s to be distinctly understood that it 1s equally applicable to and covers drylng 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. I

When the web 10 of paper, or other sheet material, is to be dried in the vacuum cham-' ber A, I protect it by water proof felts 11 and 12, or otherwise, so that the water of the velocity seal will not affect it.

The wet web of paper 10 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 pa er, is fed to the vacuum chamber A throug the velocity fluid seal 3 at the left of Fig. 1, being protected by the endless waterproof felts 11 and 12. These waterproof felts are wider than the web 10 of paper, or similar material, so that the sides 13, 13 of the felts 11 and 12 contact with each other and protect the sides of the web. The web 10 with its protecting waterproof felts 11 and 12 first passes through the box 14, in the form of the invention shown in Figs. 1 and 2, thence through the velocity seal 3 and into the vacuum chamber A. Up to that point the web has preferably been protected by the waterproof felts 11 and 12. As the web and the felts enter the vacuum chamber A the felts are preferably withdrawn from the web 10 so that the web can be dried or treated in the vacuum chamber.

I have shown in Fig. 1 the web 10 traveling in a straight line while the lower waterproof felt 12 is caused' to travel over the guide rollers 15, 16, 17 and 18. The upper waterproof felt 11 is likewise caused to travel over the guide rollers 19, 20, 21 and 22. In this manner the web is protected while passing through the velocity seals but exposed while. in the vacuum chamber A.

As the dry web 10 passes out of the vacuum chamber it is again protected by the waterproof felts 11 and 12 as it passes through the velocity seal at the exit end of the chamber. The lower waterproof felt 12 passes over the guide rollers 23, 24, 25 and 26 in an endless circuit traveling at the same speed that the web is traveling. The upper waterproof felt 11 travels in the same manner over the guide rollers 27, 28, 29 and 30.

Instead of employing water as the fluid in the velocity seal at the exit end of the vacuum chamber A, I may use steam, air or any other suitable fluid as described in my said parent application of which this is a divislon.

In the form of the invention shown in Figs. 1 and 3 the water of the velocity seal is collected in the boxes 14, 14 and withdrawn by the pipes 31, 31 to be used again in the velocity seals, or the water may be permitted to run to waste.

In some cases I may omit'the boxes, 14, 14. I have shown such a construction in Fig. 4.

In some cases I dry the web 10 by passing it over one or more drying drums or cylinders mounted in the vacuum chamber A.

In Fig. 3, I have shown such a construc- .tion in which the Web 10 and the upper and lower felts 11 and 12' pass through the velocity seal at the left of Fig. 3 and into the vacuum chamber A. The web 10 then passes in contact with the heated drying drums or cylinders 32, 33, 34, 35 and 36 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 lower felt 12, while in the vacuum chamber passes over the drying drums or cylinders 32, 34 and 36 and over the guide rollers 37, 38, 39, 40 and 41. The guide rollers 39 and 42 may be made hollow and heated in any suitable manner to dry the felt 12 if desired. The upper felt 11 passes over the drying drums or cylinders 32, 33, 35 and 36 and over the guide rollers 45, 46, 47 and 48. I The guide roller 47 may be enlarged and heated in any suitable manner to drythe upper felt 11 if this is found desirable.

Steam, air or any suitable fluid may be used in the velocity'seal at the exit end of the vacuum chamber, the same as previously described in connection with Fig. 1.

My method possesses many advantages known that the minimum temperature 212,

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 dlsadvantages, and yet it is used today and has been in use 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 ineflicient and costly, because it requires many separate manipulations, is extremely slow, uses extensive floor space and wastes heat. I

The process which is employed in the ordinary paper machine in common use, is likewise subject to many disadvantages. In such machine, the wet paper as it comes from the paper machine, is passed over many revolving cylinders, heated internally by steam to sufficiently high degree of heat to raise the temperature of the water in the paper to 212 F., the atmospheric boiling point of water. It is customary to supply the drying cylinders with steam at approximately 5.3 pounds gauge pressure, at which the steam has a temperature of 228 F., giving a difference of temperature (228- 2-12) of only 16 F. With 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 re uirement. The thermal efficiency of atmosp eric 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 constantl saturated with moisture as to rust and u timately destroy all iron and steel materials, and produces an exceedingly disagreeable and unhealthy atmosphere in which to work. It is well the atmospheric boiling point of water. is positively injurious 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 atmospheric drying process rea vacuum of about 28" of mercury, in which 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.X8=128 F.) than the temperature ifi'erence in atmospheric drying. In my improved method the paper dries approximately 8 times faster than in atmospheric drying, and I require only about one-eighth the number of drying cylinders to dry paper at the same rate of speed. I am able to dry paper with 5 c linders in the same time re quired of 40 cy inders drying at atmospheric pressure, resulting in great economies in cost of the machine, floor space and of necessary piping, felts, auxiliary equipment, and

particularly in power and maintenance in the piping system, and other inefliciencies,

it 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 steam required to dry a ton of paper by my method is approximately 5200 pounds.

It is an established fact that paper dried at low temperatures is much stronger thanwhen 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. When paper is dried by my method, therefore, a cheaper furnish or stock can be used and still produce a ,paper equal in strength to atmospheric dried paper, in which a higher grade furnish or stock is used. In making newsprint pa er, I am able to dispense with a considera 1e 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 asit passes over the cylinders.

Furthermore, 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 exhaustersare 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 blownthrough the dryer section, which will lower the temperature 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 thatthe 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 .diiferent 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 a vacuum .cham her having an opening for the admission of material into said vacuum chamber to be treated, consisting in preventing admission of air through said opening by passing water outward through said opening in the vacuum chamber under s uflicient velocity to prevent tghe admission of air into the vacuum cham- 2. The method of feeding a web of wet paper protected by water-resisting means into and out of a vacuum chamber through water moving outward with sufficient velocity to prevent the admission of air into the vacuum chamber and drying the web of wet paper in the vacuum chamber.

3. The method of drying a web of sheet material consisting in feeding the web into a vacuum chamber having a velocity fluid seal, the fluid of said seal having an affinity for the sheet material, and protecting the sheet material while in the velocity fluid seal from the fluid of said seal and drying the web of sheet material in the vacuum chamber.

4. The method of drying a web of paper consisting in feeding the web of paper into a vacuum-chamber having a velocity fluid seal, the fluid of said seal having an afiinity for-the paper, and protecting the web of paper while in the velocity fluid seal from the fluid ofsaid seal and drying said web of paper in the vacuum chamber.

5. The method of drying. a web of sheet material consisting in feeding the web into a vacuum chamber having a. velocity water seal, the water of said seal having an of finity for the sheet material, and protecting the sheet material while in the velocit fluid seal from the water of said seal and rying said web of sheet material in the vacuum chamber. 4

*6. The method of drying a web ofpaper consisting in feeding the web of paper into a vacuum chamber having a velocity water seal, the Water of said seal having an afiinity for the paper, and protecting the web of paper while in the velocity fluid seal from the water of said seal and drying said web of paper in the vacuum chamber.

7. The method of continuously drying a web of paper consisting in continuously feeding the web of paper into a vacuum chamber having a velocity fluid seal, the

fluid of said seal having an aflinity for the paper, protecting the web of paper while in the velocity fluid seal from the fluid of saidseal, drying the web in the vacuum chamber, and continuously passing the dry Web out through a seal protectingthe exit opening of the vacuum chamber.

8. The method of continuously drying a web of paper consisting in continuously feeding the web of paper into a vacuum chamber having a velocity fluid seal, the fluid of said seal having an affinity for the paper, protecting the web of paper while in the velocity fluid seal from the fluid of said seal, drying the web in the vacuum chamber, and continuously passing the dry web out through a velocity fluid seal protecting the exit opening of the vacuum chamber.

9. The method of continuously drying a web of paper consisting in continuously feeding the web of paper into a vacuum chamber having a velocity fluid seal the fluid of said seal having an afiinity for the paper, protecting the web of paper while in the velocity fluid seal from the fluid of said seal, drying the web in the vacuum chamber by passing the web over one or more heated rying drums or cylinders, and continuously passing the dry web out through a seal protecting the exit opening of the vacuum chamber.

10. In a vacuum apparatus the combination of a vacuum chamber having one or more openings therein for the admission of material into said vacuum chamber to be treated and for its passage therefrom, and

her, the fluid of said seal having an aflinity for the material to be treated, and means to protect the material against contact with the fluid in its passage through the velocity seal or seals. 1

11. In a vacuum apparatus the combination of a vacuum chamber having one or more openings therein for the admission of material into said vacuum chamber to be treated and for its passage therefrom, and one or more velocity Water seals protecting-said opening or openings andpreventing the admission of air into said vacuum chamber, the water of said seal having an affinity for the material to be treated, and means to proteot the material in its passage through the velocity seal or seals. 7

12. In a vacuum apparatus the combination of a vacuum chamber having one or more openings therein for the admission of material into said vacuum chamber to be treated and for its passage therefrom, and one or more velocity fluid seals protecting said opening or openings and preventingthe admission of air into said vacuum chamber, the fluid of said seal having an atfinity for the material to'loe treated, and Water prooi felts to contact with and protect the material in its passage through the velocity seal or seals,

13. In a vacuum apparatus for drying paper in a continuous web, the combination of a vacuum chamber having an entrance and an exitopening for the entrance and exit of a web of aper, and velocity fluid seals protecting said entrance and exit passages and preventing the admission of air into said vacuum chamber, the fluid of at least one of said seals having an affinity for the Web of paper, one or more drying drums or cylinders mounted in the vacuum cham her to dry the eb, and means to protect the Web of paper from the fluid of the seal which has an aflinity for the paper.

14. In a vacuum apparatus for drying paper in a continuous Web, the combination of a vacuum chamber having an entrance and an exit opening for the entrance and exit of a Web of paper, and velocity seals protecting said entrance and exit sages and preventing the admission. of into said vacuum chamber, the fluid least one of said seals having an at inity for the Web of paper, one or more drying drums or cylinders mounted in the vacuum chamher to dry the Web, and endless felts to protect the Web of paper from the fluid of the seal-Which has an afiinity tor the paper,

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