US2929448A - Single stage continuous paper making process and apparatus - Google Patents

Description

March 22, 1960 N. SHOUMATOFF SINGLE STAGE CONTINUOUS PAPER MAKING PROCESS AND APPARATUS Filed June 16, 1958 M 2 D A R 4 m s an s m U E .d V M m 4. ms m m 2 P m v 0 mm W 1 Pa M a H 2 NICHOLAS SHouMm'oFF United States Patent SINGLE STAGE CONTINUOUS PAPER MAKING PROCESS AND APPARATUS Application June 16, 1958, Serial No. 742,218 12 Claims. (Cl. 162-313) This invention relates to the manufacture of paper and has for its principal object the development of a method and apparatus for achieving the complete manufacture of pulp into a formed and dried paper web at a single .pass of less than a complete revolution upon the surface of a continuously rotary drum.

To this end it is a feature that means is provided for evenly depositing slightly moist pulp, desirably containing substantially no more than 67% moisture, wet basis, at a pulp receiving station on a continuously rotary drum which has an uninterrupted pervious circumferential zone. The pulp so deposited is continuously forwarded on the surface of the drum while confined out of contact with the atmosphere between the surface of the drum and a traveling, impermeable, flexible, heat conductive band or belt. Steam is applied under pressure tothe outer side of the belt, and suction is applied to the inner surface of the paper web from within the drum. The steam is first utilized primarily for its pressure effect to press the liquid out of the web and into the drum, although the steam serves also during this pressing stage to heat the liquid and thereby lower its viscosity. As the web contained liquid becomes reduced below the concentration at which it can be mechanically expressed, the action of the unit changes progressively from that of a mechanical press to an evaporating drier. The steam pressure presses the belt hard against the web, maintaining it in intimate and efficient heat conductive engagement therewith. At the same time the suction exerted from within the drum maintains the web under a substantial vacuum and thereby lowers the boiling point of the liquid while serving also to suck away the vapors. The result is that a very rapid and effective drying action is secured.

, A combined pressing and drying unit of the kind above referred to but adapted to act only upon an already formed web, is disclosed and claimed in my pending application, Serial No. 652,302, filed April 11, 1957, for Apparatus for Drying Web Material, and such unit per .se does not broadly constitute a feature of the present invention.

It is, however, a very important feature of the invention that a unit of this kind is combined with means which deposits evenly on the drum a web forming pulp which is only slightly moist. The combination is important for the reason, among others, that the web forma tion does not, as is usual in cylinder machines, require the cylinder to run partially submerged in a body of liquid. It is possible therefore to utilize almost the entire circumferential extent of the forming drum for pressing and drying, and this without the retarding of pressing and drying induced by the periodic chilling which .would occur if the drum were required to operate in a partially submerged state.

Even though the drumis used for web forming, it is possible to steam jacket all or any desired part of the ;.drum and to utilize the heat and pressure of the steam with full effect and efliciency substantially throughout the jacketed arc.

The slightly moist pulp may be deposited on the drum in an arc of the drum which is not subject to superatmospheric pressure either in a steam entrained condition or by a mechanical means. More advantageously, however, the pulp is deposited upon an arc of the drum which is under superatmospheric pressure, and for this purpose it is an important feature that steam injector means is provided, constructed and arranged to conduct the pulp into the pressure area and to deposit it in a steam entrained condition. The combination of r a unit having its pressure area extended to include the pulp receiving station, with steam injector means for delivering the pulp to such station in a steam entrained condition is regarded as an important feature of the invention.

It is a further feature that the endless impervious pressure band or belt is housed substantially completely within the steam jacket which extends around the drum, the result being that the band is heated rather than cooled in that portion of its travel in which it is out of bearing relation with the drum.

Other objects and advantages will hereinafter appear.

In the drawing forming part of this specification,

Fig. 1 is a view in sectional elevation of a practical and advantageous form of paper making machine embodying features of the invention, the section being taken on the line 1-1 of Fig. 2, looking in the direction of the arrows; and

Fig. 2 is a view in sectional elevation on a larger scale than Fig. l, the section being taken on the line 2-2 of Fig. 1, looking in the direction of the arrows.

The machine 10 comprises a closed housing 12 in which a paper web is formed from pulp, pressed and dried. The housing 12 provides a pressure chamber to which steam is delivered by the conduit 14 and from which condensate is discharged through a conduit .16. Any desired steam pressure may be employed so long as the resulting temperature is not sufficiently high to discolor or otherwise damage the Paper fibers.

The drum 18 is rotatively mounted in the housing 12. At one end the drum is fixedly secured on a shaft 20 which is rotatably mounted in a bearing 22 of the housing 12, the shaft also having fast upon it a driving gear 24 through which it is continuously driven at uniform speed by suitable driving mechanism (not shown). At the opposite end the drum has fast with it a hollow journal member 26 which is rotatably supported in. a

bearing 28 of the housing 12. The drum 18 has a wide uninterrupted, perforated, circumferential zone, and may advantageously be made to include a steam and water pervious felt cover (not shown). I

Within the drum 18 a trough 30 is provided which includes arms 32 by which it is supported in a pendent condition from the shaft 20 and the journal 26. The trough 30 serves to collect water which is mechanically pressed from the web into the drum, and any water which may be formed by condensation of steam within the drum. A suction pipe 34 extends through the hollow journal 26 and has a fixed downturned end 35 which terminates in close proximity to the trough. The pipe serves to withdraw water from the trough when water is present, and to withdraw steam when no water is present.

A housing member 36 of channel-like construction is supported in proximity to the periphery of the drum by a bracket 38. The housing 36 is connected to a suitable source of suction through a conduit 40, and conreases 67%. moisture (wet basis) isfed from a reservoir 42 by a screw conveyor 44 into a manifold conduit 46. Steam discharged under pressure into manifold 46 under the control of a manually settable valve 47 from a conduit 48, picks up and eritrains the pulp 49 and carries it through angularly disposed branch conduits 50 and nozzles 52 onto the drum 18 at a web forming station. A recirculating loop 53 is provided for maintaining adequate velocity of the pulp and steam to prevent plugging of the pipes. The pulp 49 is carried under a thin, impervious, metallic, pressure band or belt 54 which is more than wide enough to cover the pervious zone of the drum 18. As the pulp encounters the band pressure it is flattened and evened iii thickness. i

The impervious band 54 may be of any suitable thin, strong, flexible, non-rustable, heat conductive material, stainless steel being a preferred material. The band 54 istrained to run on a plurality of idler rollers 56, all of which are borne internally by the end ,walls of the housing 12. The band is driven by the paper web from the drum 18, and runs in unison with the paper web. As the web travels initially between the band and the drum, it contains suflicient moisture to admit of squeezing out through pressing. The. steam exerts a pressure upon the paper web through the band of a different order of magnitude from that which could be secured by a mere tensioning of the band, causing the paper web to be heavily compressed, and causing a substantial part of the web contained water to be pressed out of the web and sucked into the drum. This action is made more effective because the heat furnished to the web from thesteam lowers the viscosity of the water.

As the web continues its advance, there is a gradual and progressive change of operating effect from that of a mechanical press" to thatof an evaporating drier. This is brought about by the diminishing water content of the web and the continued heating of the web. The drying by evaporationis aided, of course, by (1) the high temperature of the steam in the housing 12, (2) the high pressure of the band 54 against the web, which serves both to improve the conductance of heat into. the web through the boundary between the band and the web, and also to improve the conductivity of the web itself through a compacting of the web, (3) the lowering of the. boiling temperature of the liquid inthe web by reason of the fact that the interior of the drum, and the web itself, are: maintained under a substantial vacuum, and (4) the, continual and prompt withdrawal of the vapors from the Web by the suction maintained within the drum.

'As has been pointed out above, the. drier featuresper se are disclosed and claimed in my pending application Serial No. 652,302. The present invention, however, is characterized by the fact thatthese advantages are provided over an extensive arc of the same drum upon which the webforming material is deposited in the form. of a thick pulp. Notwithstanding thefact thatthe drum 18 serves the function of a web forming cylinder,- there is relatively little water to extract, and thereis, noneed for the drum to run partially submerged. r

The fact that steam, rather than water, serves as the entraining medium for the pulp has anurnber of advantages, (1) it enables thepulp to be deliveredin fluid suspension without the employment. of a. great excess of liquid, thereby avoiding the need for filteringout and disposing of a great quantity of water, 2-) it tends to eyeri out the distribution of the fibersacross thedrurn and to dispose them completelywithout orientation so that a grainless paper having great thoughness'in the crossmachine direction will result, (3) the vehicle steam as it"s'eparates' from the. pulp within the housing 12 simply mingles with the steam introduced through the conduit 14, contributingitsmassand its latent heatto the pressiire steam, and (4) it cooperates with the housing 12 and band 54 to keep the pulp web free ffrom contaminahat'ths stea .assent d. r wns-fi been formed drum periphery and collected in the drum 18 will be pure enough for use as steam in pipes or heat exchange elements, with or without pressure and temperature boosting.

The formed and dried paper web 58 is conveyed away from the drum 18 through a peripheral exit opening of the housing 12 between the band 54 and a sealing roller 60. Beyond the ends of the roller 60 and the final idler roller 56, the drum is provided with sealing webs 62, 64, 66 which bear against the ends of said roller. These webs may be provided with strips or facings of any suitable material, desirably including a facing, at least, of a highly anti-friction material such as Teflon. Sealing strips 68 and 70 are also provided for closing the spaces between the periphery of the final idler roller 56 and the housing periphery, and between the sealing roller 60 and the housing periphery.

In order to prevent possible contamination of the finished web by splashed or floating pulp fibers, the housing 36 and the bracket 38 are made jointly to form a solid barrier between the nozzles 56 and the discharge end of the band 54.

It is a feature of considerable importance that the band 54 is completely contained within the steam pressure housing 12, and that it has only a negligibly short portion exposed to the atmosphere adjacent the point of web discharge. The band is thus caused to be heated rather than cooled when traveling out of bearing relation with the drum 18.

The illustrative machine may be supported in any suit able manner. As shown, two I-beams 72, carried by a frame structure (not shown), have the housing suspended from them.

While certain preferred embodiments of the invention have been illustrated and described in detail, it is to be understood that changes may be made therein and the invention embodied in other structures. It is not, therefore, the intention to limit the patent to the specific construction illustrated, but to cover the invention broadly in whatever form is principles may be utilized. 2 v

I claim:

I. A single stage paper making machine comprising, in combination, a rotary suction drum having a circumferential water pervious zone in its peripheral wall, an impervious, endless, flexible, heat conductive belt having an active stretch running around the major portion of the in bearing relation thereto, means for hurling moist, web-forming fibers evenly onto the drum in an area which is clear of the belt, means forming with the drum an enclosure in which the active stretch of the belt is substantially completely contained, and means for introducing hot fluid under pressure intothe enclosure to serve as an evaporating heat and pressure supplying. medium for pressing the belt againstthe web and transmitting heat through the belt to the web, and means, cooperrating with the belt for feeding the dry web, which has and dried on the drum, away from the pressure zone defined by the enclosure.

2. A single stage paper making machine comprising, in combination, a rotary suction drum having a circumferential water pervious zone in its peripheral wall; an im pervious, endless, flexible, heat conductive belt having an active stretch running around the major portion of the drum periphery in bearing relation thereto, means for hurling steam entrained, moist web-forming fibers evenly onto the drum in an area which is clear of the belt, means forming with thedrum an enclosure in which the belt is substantially completely contained, and means for introducing steam into the enclosure to serve as an-evaporating heat and pressuresupplying medium for pressing the belt against the web and transmitting heat through the belt. to the web, and means cooperating with the belt for feeding the dry web, which has been formed and dried on the away from the pressure zone defined by the enclosure,

1; 3, Asinglestagetpaper makingmachine comprising in -combination, a rotary suction drum having a circumferential water pervious zone in its peripheral wall, an impervious, endless, flexible, heat conductive belt having an active stretch running-around the major portion of the drum periphery in bearing relation thereto, means for 4 hurling moist, web forming fibers evenly onto the drum, in an area which is clear of the belt, means forming with the drum an enclosure in which the belt is substantially completely-contained, means for introducing steam into the enclosure to serve as an evaporating heat and pressure supplying medium, and means cooperating with the belt for feeding the dry web which is formed and dried on the drum away from the pressure zone defined by the enclosure.

4. A single stage paper making machine comprising, in combination, means forming a sealed enclosure, including a casing, a foraminous, rotary suction drum in the enclosure, an'imperviou's, endless, flexible, heat conductive belt disposed within the casing and having an active stretch rimning around the major portion of the drum periphery in bearing relation thereto, means for evenly hurling a thick, pulpy, web-forming, fibrous mass onto an area of the traveling drum which is clear of the belt but within the enclosure, means for introducing hot fluid under pressure into the casing to serve as an evaporating heat and pressure supplying medium, and means for feeding the dry web which has been formed and dried in the enclosure away from the pressure zone around the suction drum which is defined within the enclosure.

5. A single stage paper making machine comprising, in combination, means forming a sealed enclosure, including a casing, a forarninous, rotary suction drum in the enclosure, an impervious, endless, flexible, heat conductive belt disposed within the casing and having an active stretch running around the major portion of the drum periphery in bearing relation thereto, means for evenly hurling a thick, pulpy, web-forming, fibrous mass onto an area of the traveling drum which is clear of the belt but within the enclosure, means for introducing steam under pressure into the casing to serve as an evaporating heat and pressure supplying medium, and means for feeding the dry web which has been formed and dried in the enclosure away from the pressure zone around the suction drum which is defined within the enclosure.

6. A single stagepaper making machine comprising, in combination, means forming a sealed enclosure, including a casing, a foraminous, rotary suction drum in the enclosure, an impervious, endless, flexible, heat conductive belt disposed within the casing and having an active stretch running around the major portion of the drum periphery in bearing relation thereto, means for evenly spraying a thick, pulpy, web-forming, fibrous mass onto an area of the traveling drum which is clear of the belt but within the enclosure, means for introducing steam under pressure into the casing to serve as an evaporating heat and pressure supplying medium, and feeding rollers constituting part of the enclosure forming means and complementary to the casing, for feeding the dry web which has been formed and dried in the enclosure away from the pressure zone around the suction drum which is defined within the enclosure.

7. A single stage paper making machine comprising, in combination, means forming a sealed enclosure, including a casing, a foraminous, rotary suction drum in the enclosure, an impervious, endless, flexible, heat conductive belt disposed within the casing and having an active stretch running around the major portion of the drum periphery in unison therewith and in bearing relation thereto, steam injector means for evenly hurling moist, steam entrained, web-forming fibers onto an area of the traveling drum which is clear of the belt but within the enclosure, means for introducing steam under pressure into the casing to serve as an evaporating heat and pressure supplying medium, and feeding rollers constituting part of the enclosure forming means and complementary to the casing,

the enclosure, an impervious, endless,

(6 ing not substantially more suction drum which is defined for feeding the dry web which has been formed and dried in the enclosure away from the pressure zone around the by the enclosure.

8. A single stage paper making machine comprising, in combination, means forming a sealed enclosure, including a casing, a foraminous, rotary suction drum in flexible, heat conductive belt disposed within the casing and having an active stretch running around the major portion of the drum periphery in bearing relation thereto, means for evenly hurling a thick, pulpy, web-forming, fibrous mass onto an area of the traveling drum which is clear of the belt but within the enclosure, means for introducing steam under pressure into the casing to serve as an evaporating heat and pressur e supplying medium, and feeding rollers constituting part of the enclosure forming means and complementary to the casing, for feeding the dry web which has been formed and dried in the enclosure away from the pressure zone around the suction drum which is defined within the enclosure, the belt and suction drum cooperating first to form a mechanical water press for expressing water from the web, and thereafter, as the water content is progressively depleted, to form an evaporating heater and vapor extractor, the construction and arrangement being such that the material which entered the enclosure as discrete moist fibers, leaves the enclosure in the form of a dry paper web.

9. A single stage paper making machine comprising, in combination, means forming a sealed enclosure, including a casing, a foraminous, rotary suction drum in the enclosure, an impervious, endless, flexible, heat conductive belt disposed within the casing and having an active stretch running around the major portion of the drum periphery in bearing and sealing relation thereto, means for evenly hurling a thick, pulpy, web-forming, fibrous mass onto an exposed area of the traveling drum, means for introducing steam under pressure into the casing to serve as an evaporating heat and pressure supplying medium, and feeding rollers constituting part of the enclosure forming means and complementary to the casing, for feeding the dry web which has been formed and dried in the enclosure away from the pressure zone which is defined around the suction drum and within the enclosure, the construction and arrangement being such that the band and drum are exposed substantially continuously to a surrounding environment of steam under super-atmospheric pressure.

10. A single stage paper making machine comprising, in combination, means forming a sealed enclosure which includes a casing, a foraminous, rotary suction drum in the enclosure, an impervious, endless, flexible, heat conductive belt disposed within the casing and having an active stretch running around the major portion of the drum periphery in bearing relation thereto, means for evenly hurling a thick, pulpy, web-forming, fibrous mass onto an exposed area of the traveling drum, means for introducing hot fluid under pressure into to the casing to serve as a heat and pressure supplying medium, means for withdrawing steam from the interior of the drum comprising a suction conduit which includes a suction housing disposed in the enclosure between the drum and the casing and extending across the pervious circumferential zone of the drum, said housing having an open intake side which directly faces the drum, the construction and arrangement being such that steam which is drawn from the web into the drum from the permeable zone of the drum is drawn outward from the drum through the permeable zone and thence through said housing, and means for feeding thedry web which has been formed, pressed and dried on the drum away from the drum.

11. The method of forming, pressing and drying a paper web at a single continuous passage of less than one complete revolution upon the surface of a drum, which comprises evenly hurling fibrous material containthan 67% moisture, wet basis,

ata pulp receiving stationionto a' drum which has a circumferential, pervious zone, continuouslylforwarding the pulp on the surface of the drum' while. confiningxit between the surface of the drrum and auf'overlying;v impermeable, flexible, heat-conductive belt, ap'plyingsuctin 12. The method of forming, pressing anii' drying'a paper web at a single continuousipassage cfrle'sshtham one Complete revolutionupon the surface of a" drum, which comprises evenly hurling steam borne fibrous, web forming material containing not substantially more" than 67%moisture, wet basis,.at a pulp; receiving station, fonto a drum which has a'circumferential; petvious'zone; conthrough the belt, I the web at sub-atmospheric pressure by heat transmitted 10 away from the drum and belt.

- t-iimously forwarding thepulp on the surfaceof-thc: drum -whilc confining it 'betwe'en the; surface of the. drutnland an overlying, impermeable, flexible, heat-conductivebelt, applying suction to the. web from within the drum and concurrently applying steam under pressure't'o the outer side of the belt, first to mechanically squeeze moisture from the web into the drum by steam pressureexertd and then to evaporate moisture; from from the steam through the belt, and web, which has been formed conducting the: dry and dried on the drum,

References Cited in the file of this patent UNITED STATES PATENTS" 5 1, 161', 74 7 Stamets NW2;

2,473,270 Adams June 14, 19 9 FOREIGN PATENTS.

736,592 Germany 22 1943

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