US3541697A - High velocity through-drying system - Google Patents

Description

Nov 24, 1970 J. A. VILLALOBOS 3,

HIGH VELOCITY THROUGH-DRYING SYSTEM Filed Aug. 1, 1968 5 Sheets-Sheet '1' I IN VENTORS Jase 0b J4. Vfla/oboS BY HTTOAWEYS 1970 J. A. VILLALOBOS 3,

HIGH VELOCITY THROUGH-DRYING SYSTEM Filed Aug. 1, 1968 5 Sheets-Shet 2 IN VENTOR.

Jbse bb 14 WHO/01205 BY QT TOPNEYS Nov. 24, 1970 J. A. VILLALOBOS HIGH VELOCITY THROUGH-DRYING SYSTEM Filed Aug. 1, 1968 5' Sheets-Sheet :5

X WW n-r TORNE Y5- Nov. 24, 1970 J. A. VILLALOBOS 3,541,697

I HIGH VELOCITY THROUGH-DRYING SYSTEM 5 Sheets-Sheet 4 Filed Aug. 1, 1968 INVENTOR. Jseph 14. lfi/M/obos BY HTTOPNEYS.

Nova 24, 1970 VILLALQBQS 3,541,697

HIGH VELOCITY THROUGH-DRYING SYSTEM Filed Aug. 1, 1968 5 Sheets-Sheet 5 v Comb. Chamber 60 45 4. 42 /8 E 1 I E U I L :'v 52 I .1

IN VENTOR.

JErscph A V/'//a/obo5 United States Patent 3,541,697 HIGH VELOCITY THROUGH-DRYING SYSTEM Joseph A. Villalobos, Ramsey, N.J., assignor to AER Corporation, Ramsey, N.J., a corporation of New Jersey Filed Aug. 1, 1968, Ser. No. 749,549 Int. Cl. F26b 11/02 US. Cl. 34-115 17 Claims ABSTRACT OF THE DISCLOSURE A system for drying a wet web supported on an openwork surface in 'which nozzles direct a plurality of jets of high velocity hot air from a combustion chamber onto the surface of the web. A first portion of the high velocity air produces a scrubbing action at the surface of the web and is returned to the combustion chamber together with a quantity of water from the web. A secondary portion of the air passes through the web and through the openwork surface to an exhaust space. The system includes means for regulating the jets across the width of the web and in the direction of travel of the web with the surface. The jet-forming means is readily moved out of cooperative relationship with the surface to permit access to the interior of the system for repair and maintenance.

BACKGROUND OF THE INVENTION Various systems are known in the prior art for drying a Wet Web. In one particular arrangement known in the prior art, the web is supported on a honeycomb roll as it travels through the system. Hot air is supplied to a relatively large plenum chamber adjacent the roll. An exhaust system draws this heated air through the Web. A certain percentage of the circulating air is continuously discharged. In one form of this system, the hot air is supplied to a space over the roll, is drawn radially through the web into the interior of the roll and is exhausted axially from the ends of the roll. Alternatively, the heated air may be supplied axially through the open ends of the roll and the exhaust system may draw the air from inside the roll radially outwardly.

While systems of the type described above achieve higher drying rates than were possible with systems theretofore used, they embody a number of defects. First, the amount of air which can be drawn through the web is limited by the water content of the web and thus the possible drying rate which can be achieved is limited. Secondly, arrangements of the prior art using the system described above do not permit ready access to the roll such as is required, for example, when the web breaks, a not too rare occurrence in handling webs of the type to which the system is applied. Another drawback of systems of the type described above is that they do not ensure even drying of the web across its width. Still another defect of a system of this type is its lack of versatility. That is to say, while the arrangement is applicable to drying of a relatively permeable web, it has no utility whatever in drying impermeable webs.

I have invented an improved web drying system which overcomes the disadvantages of web drying systems of the prior art. My system achieves markedly greater drying rates than are possible by use of systems of the prior art. My improved system ensures even drying of the web across its width. Apparatus incorporating my system is arranged to permit ready access to the web supporting element in the event of web breakage or the like. My apparatus, while it is especially adapted for drying pervious webs, may be employed as well to dry imprevious webs.

One object of my invention is to provide an improved web drying system which is a high velocity throughdrying system.

Another object of my invention is to provide an improved web drying system for achieving drying rates heretofore unobtainable.

A further object of my invention is to provide an improved web drying system which permits ready access to the surface supporting the web.

A still further object of my invention is to provide an improved web drying apparatus 'which ensures even drying across the surface of the Web.

Yet another object of my invention is to provide an improved web drying apparatus which is more versatile than are drying systems of the prior art.

Other and further objects of my invention will appear from the following description.

In general my invention contemplates the provision of an improved web drying system in which jets of high velocity hot air from a combustion chamber are directed onto the surface of the wet web which is supported on an openwork roll or belt. A first portion of the high velocity air produces a scrubbing action at the surface of the web and, together with a relatively large quantity of water, is drawn away from the web surface and returned to the combustion chamber. A secondary portion of the jetted air passes through the web and through the open work surface to an exhaust space. The apparatus incorporating my system includes two hood sections which can readily be moved out of cooperative relationship with the web supporting surface to permit access thereto. Preferably, I provide means for regulating the jets of air both in a direction transversely of the web and in the direction of travel thereof.

BRIEF DESCRIPTION OF THE DRAWINGS :In the accompanying drawings which form part of the instant specification and which are to be read in conjunction therewith and in which like reference numerals are used to indicate like parts in the various views:

FIG. 1 is a perspective view of one embodiment of my improved web drying system.

FIG. 2 is an end elevation of the form of my system shown in FIG. 1 with parts removed.

FIG. 3 is a side elevation of the form of my improved web drying apparatus illustrated in FIGS. 1 and 2 with a part broken away.

FIG. 4 is a fragmentary end elevation of a portion of the system shown in FIGS. 1 to 3 with a part broken away.

FIG. 5 is a fragmentary plan view illustrating a detail of the form of my improved air drying system shown in FIGS. 1 to 4.

FIG. 6 is a schematic view illustrating an alternate embodiment of my improved web drying system.

FIG. 7 is a sectional view of my improved web drying apparatus illustrating an alternate air distribution system.

FIG. 8 is a diagrammatic view illustrating the flow of drying air in my improved Web drying system.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, my improved drying system includes a roll or drum, indicated generally by the reference character 10, around which the web 12 to be dried is trained by idler rollers 14 and 16 supported in any suitable manner known to the art. The roll or drum 10 includes a cylindrical openwork body 18 so formed as to provide a multiplicity of openings 20 leading to the interior of the body 18. Preferably the body Patented Nov. 24, 1970 18 is so constructed that from 85% to 90% of its surface is made up by the openings 20. Respective end plates 22 and 24 close the ends of the drum 10. A shaft 26 supports the drum for rotary movement in bearings 28 and 30 carried by uprights 32 and 34 supported on beams 36 and 38 which may make up part of a floor structure of a mill or the like.

For reasons to be explained more fully hereinafter, I connect respective exhaust conduits 40 and 42 through the end plates 22 and 24 of drum or roll 10 to the interior of the drum 10. These connections may be made through the end plates 20 and 22 with suitable seals 44 being provided to prevent the escape of air while permitting relative rotation between the end plates and the conduits 40 and 42. It will be appreciated that shaft 26 extends through each of the conduits 40 and 42 to the bearings 28 and 30.

My drying apparatus further includes respective hood sections, indicated generally by the reference characters 46 and 48, each of which has an enclosure comprising a top 50, an end 52, and respective sides 54 and 56. A frame 58 carried by legs 60 on the beams 36 and 38 supports the hood sections 46 and 48. I secure respective pairs of roller supports 62 and 64 to the sides 54 and 56 of each of the sections 46 and 48. The supports 62 and 64 carry respective rollers 66 and 68 which ride on cam tracks 70 and 72 on the frame 58. Piston and cylinder assemblies 74 pivotally supported on a bracket 76 on the frame have rods 78 connected to the respective roller supports 64 on the sides of frame 58. The arrangement is such that when access to the roll 10 is desired, fluid under pressure from any suitable source (not shown) may be supplied to the assemblies 74 to cause them to draw the respective sections 46 and 48 radially outwardly away from the roll 10. The shape of the cam tracks 70 and 72 is such that in the course of this movement of the sections away from the drum 10, the sections pivot slightly around the rollers 66 so as to permit access to the drum.

Each of the sections 46 and 48 includes an air supply duct 80 extending into the interior of the section through the wall 54. A return duct 82 extends through wall 54 into the space within each of the hood sections 46 and 48.

I connect each of the supply ducts 80 to a distributing header 84 extending across the width of the section 46. Respective distributor connections 86 carry air from the header 84 to respective lead-in connections 88 which direct air through openings 90 in one arcuate wall 92 of each of a number of inner high pressure air chambers 94 distributed across the sections 46 and 48. The other wall 96 of each of the chambers 94 is provided with a plurality of pairs of generally radially inwardly directed flanges 98 and 100 extending transversely of the drum 10 to form a plurality of elongated transversely extending nozzles, spaced circumferentially of the roll 10 for directing jets of high velocity air onto the surface of the web 12 supported by the openwork frame 18. Each of the distributing conduits 88 supplies one of a number of chambers 94 of the hood section arranged transversely across the roll 10. Dividers or partitions 102 extending between walls 92 and 96 are spaced across the hood to separate the chambers 94.

Adjacent each of the connecting ducts 86 I provide a respective damper 104 having a shaft 106 which extends outwardly to a handle 108 outside the hood to permit the supply of air provided by that particular distributor duct to be varied. In this Way I am able to regulate the air supplied to the web 12 over a plurality of narrow sections across its width so as to ensure that drying occurs evenly across the width of the web.

The transversely elongated jets of high velocity air emanating from the nozzles formed by flanges 98 and 100 are directed onto the surface of the web 12 so as to provide a scrubbing action thereat. As has been explained hereinabove, the amount of air which can pass through the web is limited by the amount of water contained therein.

I provide means for returning a portion of the high velocity air carrying moisture which has been removed from the web 12 by the scrubbing action referred to hereinabove. A plurality of short lengths of tubing or ports 110 extend through wall 96 at locations between the nozzles, through the chambers 94 and through the wall 92 of chambers 94 to the space within the hood section outside the high pressure air chambers 94. As has been explained hereinabove, return ducts 82 lead into this space to permit the return air to be carried out of each hood section. It will readily be appreciated of course that there are no return tubes 110 in the region wherein high velocity air is introduced by one of the distributor ducts 88.

As has been explained hereinabove, a portion of the high velocity air impinging on the surface of the web 12 is returned through the tubes 110 and through the duct 82. Another portion of this supply air travels through the web 12 and through the openings in the open frame 18 to the space within the roll 10 carrying moisture therewith. This moisture laden air is exhausted through the exhaust conduits 40 and 42 connected to the ends of the roll.

Referring now to FIG. 8, I have shown a diagrammatic view of the air system of my web drying arrangement. Any suitable means, such as a blower 112, supplies air from a combustion chamber 114 to the two inlet ducts 80 associated with the respective hood sections 46 and 48. This air produces high velocity jets through nozzles formed by flanges 98 and 100. A portion of this high velocity air impinging on the surface of the web 12 removes moisture from the web by a scrubbing action and returns through conduits 110 to the spaces within the hood sections outside the high pressure air chambers 94 and travels outwardly through the return ducts 82. This air is returned to the combustion chamber 114 as indicated schematically by the broken line 116 in FIG. 8. The other portion of the air from the jets formed by flanges 98 and 100 travels through the web and through the openings 20 in framework 18 to the space within the openwork roll 10. This air is exhausted through the ducts 40 and 42 by any suitable means such, for example, as by an exhaust blower 118.

In the structure just described, I have provided an arrangement wherein each of the hood sections 46 and 48 is divided into a plurality of sub-sections or chambers 94 transversely of the web so as to facilitate even drying across the web. In many instances it is desirable that the hood be divided additionally in the direction of travel of the web so that further control of moisture removal is possible. Referring to FIG. 7, I have shown such an arrangement in which, in addition to the partitions 102 which form the transverse sub-section, I provide another partition 120 extending transversely of the hood so as to divide the hood section into sub-sections in the direction of travel of the web. In such an arrangement I provide an auxiliary high velocity air supply duct 122 leading to a header 124 from which connecting ducts 126 direct air to distributing ducts 128 connected to openings in the wall 92 on the other side of the partition 120 from the openings 90. Baflles 130 associated respectively with the connecting ducts 128 are provided with handles 132 for regulating the flow of air from the distributing header and through the connecting duct 128 to the particular section with which that duct is associated. It will readily be appreciated that by adjusting all of the baflies 104 and 130 any desired degree of control of drying of the web both in the direction of travel thereof and across the surface thereof can be achieved. For the purpose of controlling drying of the web in the direction of travel thereof it may not be necessary to provide the additional partition or partitions 120. That is, it may be suflicient merely to provide one or more auxiliary distributing headers 124 spaced in the direction of travel of the web with respect to header 84.

I provide each of the hood sections 46 and 48 with an air seal 134 extending entirely around the periphery of the hood adjacent the roll to permit the area of the web covered by the hood to be pressurized to cause some of the air to be forced through the web. I have found this to be required to produce the optimum drying rates even though a negative pressure exists within the drum. Seals 134 may be of any suitable construction which will prevent the hot high velocity air from spilling out around the edge of the hood section. I have found that a flexible wire brush-like seal which presents a large pressure drop to the air flow while at the same time having sufiicient flexibility to accommodate expected variations in drum circumference is suitable for this purpose. Each of the hoods further includes a closure plate 136 extending from adjacent the upper portion of the roll 10 at the center thereof to the top wall 50 of the corresponding hood.

Referring now to FIG. 6, I have shoWn an alternate embodiment of my improved web drying system in which an openwork endless conveyor or belt 138 carried by rolls 140 and 142 is adapted to support a web 144 to be dried for movement in the direction if the air indicated in the figure. I arrange a hood, indicated generally by the reference character 146, over the web 144 on the upper portion of the belt 138 between rolls 140 and 142. Hood 146 includes a first chamber 148 to which I supply high velocity air by means of a duct 150. Chamber 148 includes an upper wall or partition 152 and a lower wall 154. I form wall 154 with a plurality of pairs of downwardly extending flanges 156 and 158 directed toward each other so as to form nozzles extending transversely of the web 144 It will readily be appreciated that the hood 146 can be divided into sections across the web 144 as well as sections along the length of the web in a manner analogous to that in which sections are formed in the embodiment of my invention described hereinabove.

A plurality of return conduits 159 extend through portions of the lower chamber wall 154 between flanges 156 and 158 and through the upper wall 150 to a space 160 within the hood above chamber 148. I connect a return duct 162 to the space 160 so as to return air to the combustion chamber. I provide a seal 164 around the periphery of hood 146 at the bottom thereof so as to prevent the escape of hot high velocity air from under the hood.

An exhaust chamber 166 below the upper portion of conveyor 138 registers with the hood 146. A portion of the high velocity air supplied by the nozzles formed by flanges 156 and 158 passes through the web 144 and through the openwork conveyor 138 to chamber 166. An exhaust conduit 168 carries the air from chamber 166 to the exhaust.

In operation of my improved high velocity throughair drying system, air under pressure is supplied to both ducts 80 from the combustion chamber 114. The amount of this air passing to each of the sections of the hoods can be regulated by adjusting dampers 104- to ensure even drying across the web 12. If desired, the machine may be divided into sections in the direction of travel of the Web and baffles 130 can be adjusted to control the relative drying effect of the two sections in the direction of travel of the Web.

Air supplied by the ducts 80 travels through the header 84 down through the connecting ducts 86, past the dampers 104 and through distributing ducts 88 to the high pressure air space 94 This air emerges from the nozzles formed by flanges 98 and 100' in the form of transversely elongated jets of high velocity air. By way of example, the air emerging from the nozzles formed by the pairs of flanges may have a velocity of the order of about 20,000 f.p.m. It may be at a temperature of about 600 F. In order for maximum drying with a minimum horsepower expenditure to be achieved, it is desirable that the nozzels be very close to the web. The web itself may be travelling at a speed of between 3,000 to 4,000 f.p.m.

The high velocity hot air impinging on the surface of the web 12 produces a scrubbing action thereat so that a relatively large quantity of moisture is picked up by this air. A portion of the high velocity air carrying moisture travels backwardly through the return ducts to the space within the hood outside the chamber 94 from whence it is returned to the combustion chamber through the return duct 82. Another portion of the air supplied by the nozzles travels through the web and into the space inside the roll 10. It will be understood that as the air travels through the web, it picks up additional moisture. This through air is carried to the exhaust through the conduits 40 and 42.

I have discovered that a suitable inter-nozzle spacing for use in my system is about 3 /2 inches between centers. Under the conditions described above, I have been able to achieve a drying rate of between 30 to 35 lbs. of water per square foot per hour as contrasted with a drying rate of about 20 lbs. of water per square foot per hour by systems of the prior art described above.

As has been pointed out hereinabove, web speed in a system to which I may apply my dryer is from 3,000 to 4,000 f.p.m. In the event that there is a web break, very large quantities of paper accumulate before the apparatus can be stopped. With the relatively high temperature of the air being supplied, it is essential that the system be able to be opened up rapidly so as to permit the web carrier to be cleared in order to avoid the danger of fire. In my system, if such a break occurs, the apparatus is stopped and fluid under pressure is at once applied to the cylinders 74 to cause them to move the hood sections 46 and 48 outwardly of the roll 10' and to tilt them slightly in the course of so doing to permit ready access to the cylinders.

It will be seen that I have accomplished the objects of my invention. I have provided an improved web drying system for achieving much higher drying rates than are possible by use of systems of the prior art. My system is so arranged as to ensure even drying of the web. It permits ready access to the inside of the hood in the event of a Web break or the like.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of my claims. It is further obvious that various changes may be made in details within the scope of my claims without departing from the spirit of my invention. It is, therefore, to be understood that my invention is not to be limited to the specific details shown and described.

Having thus described my invention, What I claim is:

1. A system for drying a web including in combination, means providing a foraminous surface for supporting said web with an outer surface of the web remote from said foraminous surface, means for directing a plurality of jets of high velocity drying gas onto said outer surface of the supported web, means for removing a portion of said gas in a direction outwardly from said outer surface after impingement thereon while permitting a portion of the gas to pass through said web and through said foraminous surface and means for removing another portion of the gas which has passed through said surface.

2. A system as in claim 1 in which said jet directing means is elongated transversely of said supporting surface.

3. A system as in claim 1 in which said jets are positioned across said surface.

4. A system as in claim 1 in which said jets are elongated and extend transversely of the surface.

5. A system as in claim 1 in which said jets extend transversely of said surface and means for regulating the amount of air supplied tothe respective jets.

6. A system as in claim 1 in which said jets are positioned along said surface and means for individually regulating the air supplied to the respective jets.

7. A system for drying a web including in combination, means providing a foraminous surface for supporting said web with an outer surface of the web remote from said foraminous surface, a hood provided with a pressure chamber formed in part by a first wall conforming generally to the shape of a portion of said foraminous surface and by a second wall spaced from said first wall, means forming a plurality of nozzles in said first wall, means for supplying gas under pressure to said chamber to produce a plurality of high velocity jets of gas from said nozzles directed toward said outer surface of said web on said foraminous surface, means for removing a first portion of said gas outwardly from said outer surface after impingement thereon and for returning said first portion of the gas to said supplying means and means for removing another portion of said gas which has passed through said surface.

8. A system as in claim 7 in which said surface providing means is a drum.

9. A system as in claim 7 in which said surface providing means is a horizontally disposed conveyor.

10. A system as in claim 7 including means providing a seal between the first wall and said surface providing means, said seal extending around said first wall.

11. A system as in claim 7 including a flexible wire brush seal between said first wall and said surface providing means, said seal extending around the periphery of said first wall.

12. A system as in claim 7 in which said means for returning said first portion of said high velocity air comprises a duct extending through said first and second Walls between said nozzles.

13. A system as in claim 7 including means mounting said hood for movement with relation to said surface providing means and actuatable means for moving said hood away from said surface providing means 14. A system as in claim 7 including means for regulating the supply of gas to said nozzles in a direction transversely of said surface-providing means.

15. A system as in claim 7 including means for moving said surface providing means and means for regulating the supply of gas to respective nozzles in the direction of movement of said surface-providing means.

16. A system as in claim 7 including means for moving said surface providing means, means for regulating the supply of gas in a direction transverse to said direction of movement and means for regulating the supply of gas in said direction of movement.

1'7. A system for drying a Wet web including in combination, a drum having a generally cylindrical foraminous wall and having a pair of end plates, a first hood section provided with a pressure chamber formed in part by a first wall conforming generally to the shape of a portion of said surface and by a second wall spared from the first wall, means forming a plurality of nozzles in said first wall, a second hood section having a pressure chamber formed in part by a first wall conforming generally to the shape of another portion of said surface and by a second wall spared from the first wall, means forming a plurality of nozzles in the second section first wall, means mounting the respective hood sections for movement between operative positions at which the first walls are adjacent to said surface and inoperative positions at which the first walls are remote from said surface, means at the peripheries of said first walls forming air seals between the sections and the surface in the operative positions of the sections, means for supplying gas under under pressure to said chambers to produce a plurality of high velocity of jets of gas from said nozzles directed toward said web or said surface, means for returning a portion of the gas directed against said web to said supplying means, and means for removing another portion of said gas through said web.

References Cited UNITED STATES PATENTS 1,533,086 4/1925 Baker 34-131 X 3,222,279 12/1965 Taylor 34122 3,284,920 11/1966 Hayrinen et al. 34122 3,406,466 10/1968 Smith 34-155 3,435,751 4/1969 Goodman et a1. 34155 X 3,447,247 6/1969 Daane 34-155 X ROBERT A. OLEARY, Primary Examiner T. W. STREULE, Assistant Examiner US. Cl. X.R. 34-122, 155

253 3 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION P.tent N 3 Datd NoVeInber 24,

Inventor) Joseph A. Villalobos It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 7, line 35:

A period should be inserted after 'means" Column 8, line 9:

" spared" should be spaced Column 8, line 14:

" spared" should be spaced Column 8, line 23:

"under" (second occurrence) should be deleted.

new) MD 8.21250 B Atteat:

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