US3063692A - Means for drying paper and like materials - Google Patents

Description

Nov. 13, 1962 E. A. TIMSON MEANS FOR DRYING PAPER AND LIKE MATERIALS 3 Sheets-Sheet 1 Filed Jan. 21, 1960 l n ventor ERHIST ARTHUR TIKSON Nov. 13, 1962 E. A. TIMSON MEANS FOR DRYING PAPER AND LIKE MATERIALS Filed Jan. 21, 1960 .3 Sheets-Sheet 2 Inventor IRNIS'I ARTHUR IIHSON q I w I a 7/////%/ //m I m I w M W. I v s: u I W s m m m v m n MN I. w QT" .H I I" V u i |Wn 1 W a 7/ F V W I K N m N M B I 12m! Attorney Nov. 13, 1962 E. A. TlMSON 3,063,692

MEANS FOR DRYING PAPER AND LIKE MATERIALS Filed Jan. 21, 1960 3 Sheets-Sheet 3 Inventor ERNEST ARTHUR TIMSON f Attorney I United States Patent Ofiice 3,063,692 Patented Nov. l3, 1962 3,063,692 MEANS FQR DRYING PAPER AND LIKE MATERIALS Ernest Arthur Timson, 75 Northampton Road, Kettering, England Filed Jan. 21, 1960, Ser. No. 3,883 Claims priority, application Great Britain Jan. 27, H59 2 Claims. ((31. 263-3) This invention appertains to the heating of relatively thin and flexible materials such as paper, textile or knitted fabrics, film, foil and the like requiring to be dried after having been operated upon by, or treated in, a process involving the deposition of moisture or certain materials upon, or the application of inks, stains, dyes or other liquids to, surfaces of such materials.

Although primarily intended for the drying of travelling webs of the said materials, the invention is not limited in this regard a it may also be employed for drying series or successions of suitably conveyed separate sheets.

The invention, moreover, has reference to drying apparatus for the purposes specified and of the kind comprising a defined drying zone in which at least one fluid fuel burner is provided, and means for supporting and guiding a web or webs or one or more series of conveyed sheets in the course of being drawn through the said zone past the burner or burners.

For instance, an apparatus of this kind is suitable for drying travelling webs of paper after they have passed through a printing machine and been printed upon with a volatile ink or like medium, the purpose of the drying process in this instance being to expedite evaporation of the solvent in the medium.

Such an apparatus is also suitable for the drying of films by, for instance, penetration, polymerization, oxidation and other drying processes all of which are accelerated by heat. The fusion of powders distributed on webs, as in electronographic methods of printing, is another process capable of being carried out by an apparatus of the kind concerned.

Heretofore, a drying apparatus of the kind concerned has usually incorporated burners of a type requiring to be supplied with fuel gas or vapour and air under substantial pressure and adapted to produce very high temperatures of the order of from, say, l,800 C. to 2,000 C. and

over.

For example, in certain prior apparatus the aim has been to heat a web uniformly by the employment of at least one multiple burner which extends transversely the full width of the web and has separate, uniformly spaced orifices designed to ettect uniform gas distribution. Such burners have produced hard flames, by mixture of gas and air in theoretical proportions for complete combustion. The intention has been that the high velocities of these hard, minimum volume/maximum temperature, flames, should displace the dead occluded air film carried by the web. The efliciency of each multiple burners, however, has not been very high, and any apparatus embodying the same as far as is known is only capable of drying one side of a web at a time.

It has also previously been proposed to provide burners each comprising a plurality of thin metal strips laid against one another so as to form a pack.

Other pressure gas burners heretofore provided for the purposes in view included radiators of refractory material heated to incandescence by the gas flames and arranged to direct the flames and radiant heat directly against the webs of material in a direction normal or approximately so thereto. Such burners give out a heat so intense that it is capable of raising the temperature of, say, paper far above its scorching point, the period of the application of such heat being, however, limited, to prevent burning or charring of the paper.

Ribbon gas flame burners into which gas is pumped under pressure have also been proposed for use in drying printed webs of paper arranged to run at speed.

In yet another prior drying apparatus, gas radiant heating elements, associated with individual or common reflectors, give out such an intense heat as to necessitate the provision of removable heat insulating means adapted to screen the flexible sheet material from the said elements when the drying chamber is closed and from the operator when the chamber is open.

An object of the present invention is to provide, in a drying apparatus of the kind herein referred to, a burner capable of generating a flame which, being gentler and substantially less hot than burner flames previously used for the same purposes, is found to provide certain advantages as will be hereinafter described.

A further object is the provision, in such an apparatus, of a burner which although designed to generate a large volume flat flame, itself remains relatively cool.

According to this invention, a fluid fuel burner provided in the drying zone of an apparatus of the kind referred to is of a form adapted to produce, by admixture therein of combustible fluid fuel with air at atmospheric pressure, an only moderately hot, in contradistinction to a high temperature, flame which issues lazily from the burner suchwise as to be carried along, and to flow together and in contact, with the travelling material to be dried.

By an only moderately hot flame is meant one of the average order of from 900 C. to 1400 0, depending on the zone considered, in contradistinction to an in tensely hot flame of anything up to 2,200 C.

In this regard it has to be borne in mind that a lazy flame comprises zones of various temperatures.

The longitudinal flow of the flame in the direction of movement of, and hence in company with, the travelling material is c'ompartively sluggish since, unlike burners in prior arrangements, there is no forced draught and blast of air through the burner directing the flame straight at the said material. In other words, the flame issuing from the burner spreads longitudinally as well as trans versely with respect to the path of travel of the material. The travelling material is accordingly contacted by a gentle flame which has a comparatively large area in contact with the web.

Moreover, this flame, being etfective over a comparatively large. area of the travelling material, and notwithstanding the fact that the temperature of the flame is only moderate, is adequate to dry, say, ink printed on paper and avoid the necessity to concentrate-repeatedly as necessarya substantially more intense heat upon a much smaller area of the material. As a consequence, any tendency to alter the physical properties and dimensions of paper during drying is minimised.

In order that the invention may be more clearly understood and readily carried into practical effect, a specific arrangement of gas burners in a web dryer will now be described by way of example, with reference to the accompanying purely diagrammatic drawings, wherein,

FIGURE 1 is a longitudinal sectional view of the said dryer showing not only web travelling therethrough but also the longitudinal flow of a low temperature lazy gas flame beneath the said web,

FIGURE 2 is a sectional plan view of the dryer taken on the line l1-l1 of FIGURE 1, and with a portion of the web torn away to show the arrangement of the gas burners and the longitudinal as well as the transverse spread of the lazy flame issuing therefrom,

FIGURE 3 is a detail plan view, partly in section, illustrating the means whereby a mixture of gas and air, at atmospheric pressure, is injected into a gas pipe or manifold common to a plurality of burners,

FIGURE 4 is a detail elevational view of one of the aerated burners provided in the drying chamber of the web dryer, and

FIGURE is a front view of the said burner.

The-specific web dryer shown in the drawings comprises a drying chamber "1 inwhich two gas burners 2 are provided, and means consisting of guide rollers 3 and 4 and water cooled cylinders 5 and 6 for supporting and guiding a web W of paper in the course of being drawn through the said chamber, past the burners 2, in the direction of the arrows A. The web W enters the chamber 1 through an entrance slot or aperture"? formed in the appropriate end wall 1a of the chamber, and leaves the latter through an exit slot or aperture 8 formed in the opposite end wall 1b. The guide roller 3 is disposed transversely'at right angles to the web W a small distance only aheadof the entrance slot or aperture 7, Whereas the gmide roller 4 is similarly disposed after the water cooled cylinders 5 and 6 which letter are arranged one above the other adjacent to the exit slot or aperture 8-.

In the specific example illustrated, there is provided in the drying chamber 1, fairly near to and below the entrance slot or aperture 8, a common gas pipe or manifold 9 furnished with two suitably spaced branches It) on to the end of each of which is connected one of the gas burners 2. The pipe or manifold 9 is mounted so as to extend transversely across the path of the travelling web W.

Advantageously, the lazy low temperature flame F issuing from each of the burners 2 has a substantial spread of anything from about to approximately 30", and each burner may as shown in FIGURES 1 and 2, be arranged to operate beneath the web W and so as to project its volume of flame F in the same direction as that in which the web travels. Moreover, each such burner .2 may be so arranged that the volume of flame slopes upwardly somewhat, thereby ensuring close intimate contact with the web W. The web W preferably also slopes upwards, as clearly shown in FIGURE 1, to assist the flame F to keep pace with the web and to limit the extent of the lateral spread of the flames. In this regard, the relative heightwise dispositions of the slots or apertures 7 and 8, and the arrangement of the guide roller 3 in relation to the upper water cooled cylinder 5 are such that the web travels uphill away from the burners. The angle a indicated in FIGURE 1 is one of 8.

The persistent lazy flames F have adequate time for their heat to penetrate not only the dead occluded air film carried by the web W but also the web thickness itself. The heat from the flames therefore thoroughly warms the entire thickness of the web W, and ink films on either or both sides of such a web are equally dried, or substantially so.

It may be advisable, however, to provide above the Web W a row of small burners, such as that indicated in FIGURE 1 at 11, to burn off the volatile products given off from the drying ink.

Whereas hard, hot flames slightly too wide for the web tend to scorch the edges of the later, soft lazy flames do not do this even if they overlap such edges.

The aerated burners 2 may be of the Bunsen type, depending on the characteristics of the gas used, and by arranging for the flow'therethrough of a current of air, if required, the lazy flames F produced are substantially hon-luminous, or weakly luminous, so as just to avoid thedeposition of carbon upon the surface of the paper or other material being dried.

In accordance with an important feature of the present invention, moreover, each of the burners provided in the drying chamber 1 of the apparatus may advantageous- 1y be of a form adapted to produce a laterally spread, flat flame F which is very wide in relation to its thickness. Thus, such a flame may conveniently be of a known fan shape akin to that of a bats wing (see more especially FIGURE 3). By virtue of this feature, the number of burners required adequately to cover the full width of the travelling material to be dried can be reduced to a minimum.

A further feature of a gas burner of the form adopted for the purposes of the present invention is that the mixture of gas and air issuing therefrom burns a little ahead or in front of the burner. As, therefore, the widely spread, lazy flame F is spaced from the burner, the body of the latter remains relatively cool so that whenever the supply of gas to the burner is cut off and the flame is extinguished there is only a minimum emission of heat from the burner. This small amount of heat is, in fact, insuiflcient to scorch or fire the travelling web which tends to slacken and touch the burners 2 during a stoppage of the apparatus. Accordingly, any necessity to provide cover plates or shields to protect the material in these circumstances is obviated.

Although it is primarily the intentions to supply the burners with coal or Town gas, there is no limitation in this respect since manifestly the burners could be supplied With any other suitable fluid fuel, such as methane or butane, or with liquid fuel such as oil or paraflin vapour, the fluid fuel being mixed with air at atmospheric pressure when necessary.

It is convenient to employ for the purposes in view gas burners each in the form of a hollow jet having in its outer, mainly closed end a comparatively small outlet aperture communicating with a comparatively wide recess which has an inwardly shaped, e.g. concave, bottom designed to achieve diffusion of the combustible mixture of .gas and air issuing through the said aperture and at the same time producing a wide, thin flame such as F of fan or bats wing shape acquiring the sufficiency of air for complete combustion by free turbulence.

As a specific example of a suitable aerated burner of this form may be quoted the Hypact burner which was developed by the Research Laboratory of the Gas, Light & Coke Company. This hollow cylindrical burner 2, illustrated in FIGURES 4 and 5, is in the nature of an enlarged industrial jet or nozzle, fabricated throughout in metal and adapted to be connected on to the end of a branch 10 of the gas pipe or manifold 9. In the outer surface 2a of the comparatively thick mainly-closed end 2b of the Hypact burner 2 is milled a diametral, concave recess 12. In the bottom of this recess, centrally between its ends, is a small rectangular outlet aperture 13 communicating with the hollow interior '14 of the cylindrical burner, this aperture being produced by forming in the inner surface 20 of the mainly closed end 2b a diametral channel extending at right angles to the milled concave recess 12. By virtue of the formation described a marked degree of aeration is obtained by turbulence.

In FIGURE 3 is depicted an injector 15 for injecting into the common gas pipe or manifold 2a mixture of coal or Town gas at mains pressure with air at atmospheric pressure. As will be seen, the gas issues from a jet 16 into a flared end 17a of a tube 17 of smaller diameter than the surrounding tubular portion 18:: of the injector casing 18. Air inlet apertures are formed in the tubular portion 18a, adjacent to the leading end of the jet 16, to admit air into the interior of the tube 17, whilst similar inlet apertures 20 are formed in the said tubular portion to admit air into the annular space between the injector casing 18 and the exterior of the tube 17. By virtue of this arrangement a thorough admixture of the gas and air is produced for continuous supply to the burners 2.

Such an arrangement as that illustrated in the drawings is particularly suitable for directing lazy flames on to the underside of a printed web of paper for the purpose of drying printing on either or both sides by heat.

The heightwise dimension of the entrance slot 7 may, if desired, be adjustable to enable the opposed horizontal edges of this slot to be set close to the respectively opposite sides of the travelling Web W. In this way, undesired insulating films of air which would otherwise be drawn into the chamber 1 by the web are disturbed and broken by the edges of the slot to facilitate the drying action of the flames F. The edges of an adjustable entrance slot may be constituted by edges of manually adjustable plates located on the end of the drying chamber.

Iclaim:

1. In a web dryer, in combination, a heating chamber having in its opposite ends entrance an exit apertures respectively, means supporting and guiding a Web of paper or the like as it is drawn and caused to travel through said chamber, a gas manifold which has spaced branches and is mounted in said chamber adjacent said entrance apertLu'e so as to extend transversely across a plane projected through said entrance and exit apertures, a plurality of gas burners fitted on said branches of said manifold and directed at an acute angle towards said plane extended through said entrance and exit apertures, and means supplying said burners via said manifold with an admixture of gas with air at atmospheric pressure, each of said burners being of hollow cylindrical form and having an outer surface with a thick mainly closed outer end, said outer end having milled therein a diametral concave recess and there being provided in the bottom of said recess a small outlet aperture centrally between the ends of said recess and extending diametrally at right angles to said recess and communicating with the hollow interior of said cylindrical burner, so as to produce a wide thin flame which is moderately hot having zones of various temperatures of the average order of from 900 C. to 1400" C., and issues lazily from the burner so as to be carried along, and to flow together and in contact with the traveling web, the longitudinal flow of the flame being sluggish, and the flame spreading longitudinally as Well as transversely with respect of the aforesaid path of travel so as to have a comparatively large area in contact with the web.

2. In a Web dryer adapted to dry a travelling web of paper which has been printed upon with a volatile ink, a combination according to claim 1, which includes a row of small gas burners arranged above said plane to burn off the volatile products given ofl from the drying ink.

References Cited in the tile of this patent UNITED STATES PATENTS 94,103 Gill Aug. 24, 1869 677,171 Bernson June 25, 1901 2,099,162 Eberlin Nov. 16, 1937 2,204,802 Gessler June 18, 1940 2,225,166 Erby Dec. 17, 1940 FOREIGN PATENTS 349,849 Italy June 24, 1937

Images