US3162568A

US3162568A - Press units for moisture removal

Info

Publication number: US3162568A
Application number: US97914A
Authority: US
Inventors: James E Post
Original assignee: Individual
Current assignee: Individual
Priority date: 1961-03-23
Filing date: 1961-03-23
Publication date: 1964-12-22
Anticipated expiration: 1981-12-22

Description

Dec. 22, 1964 J. E. POST mass UNITS FOR MOISTURE REMOVAL Filed March 23. 196].

TO JOURNAL www FIG?) FIG.4

United States Patent ERESS UNlTS FOR MGR'STURE REMOVAL James E. Post, Samoset Road, Box 367, South Duxhui y, Mass.

Filed Mar. 23, 1961, Ser. No. 97,914 3 Claims. (Cl. 162-358} This invention relates to the extraction of liquid from a moving web or sheet and, more particularly, to press units for use in paper-making machines. for extracting water from a web of pulp or paper that is carried on or between a porous material such as a felt member or belt.

A principal object of the present invention is to provide improved press or pressure units or assemblages for the more efficient and economical removal of water from a rapidly moving web or sheet of material such as paper.

Still another object of the invention is to provide an improved lower press unit or assemblage comprising an endless belt or blanket of a resilient material such as rubher having on one surface thereof a plurality or profusion of holes of predetermined depth.

Still another object of the invention is to provide an improved upper press roll or unit having a porous structure through which hot air or steam may be passed.

A still further object of the invention is to utilize said improved upper press roll and lower press unit in combination in, for example, a paper-making machine.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the apparatus possessing the construction, combination of elements md arrangement of par-ts which are exemplified in the following detailed disclosure and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings wherein:

FIGURE 1 is an isometric view, with parts in section, showing a web of wet paper carried by a felt belt passing between the preferred press units or assemblages of the invention;

H6. 2 is n isometric view, with parts in section, she ing a web of wet paper carried between two felt belts passing between the preferred press units of the invention; and

FIGS. 3 and 4 are cross-sectional views of the endless belt of the lower press unit showing the preferred constructions of the holes or wells present in said belt.

in the manufacture of paper, it is generally the practice to convey a web or sheet of paper, after it is formed on the Fourdrinie-r wire or other sheet-forming device and which contains about 85 percent or more of water, through the presses and then through the dryers for the removal of water. In the press part of a paper-making machine, the web of wet paper is carried by the aid of one or more press felts between pressure rolls for the purpose of squeezing or pressing water from the web by pressure exerted between the rolls. These rolls are generally arranged in vertical or superposed pairs, two, three or more pairs being employed. The lower roll, or each lower roll of the press may be a suction roll, that is, provided with means for removing water from the paper web by the application of a vacuum, or it may be a plain roll, that is, without perforations.

One form of lower press roll which is frequently employed is a metal shell provided with a plurality of perforations which rotate past a suitably positioned suction box. The outer surface of the shell is generally provided with a layer or covering of a relatively soft material such as rubber which is provided with perforations which are in substantial alignment with the shell perforations 50 that the wet paper web conveyed between the press rolls is subject to a vacuum for removing water therefrom. These suction rolls are generally quite expensive.

The upper or top press roll which may be made of various metals, such as cast iron, brass or bronze jacketed cast iron, or the like, or of rubber, wood such as maple, stone such as granite or other non-rusting material or composition is always provided with a smooth surface. The pressure, exerted between the rolls may be due to the weight of the upper press roll alone or to the weight of said roll and additional pressure applied, for example, to the journals of the upper press roll.

- Heretofore known perforated coated lower press rolls possess several disadvantages. For example, since the shell is usually made of metal, difiiculties are frequently encountered in obtaining a strong adherent bond between the metal shell and the covering which is usually rubber. Obviously separation of the covering from the shell can have several undesirable efiects such as slippage of the covering which may cause misalignment of the perforations and thus appreciably reduce the removal of water by suction, or tearing of the covering so as to necessitate shutdown of the machine. Another difficulty is in securing alignment or registry of the perforations in the covering with those in the underlying-metal shell. Still another disadvantage is that when it is desired to replace or recover a lower press roll, it must be removed fromv the paper-making machine which may be difficult due to the size and weight thereof and may also be time consuming thus resulting in expensive down-time. Another disadvantage resides in the fact that it usually is notpo'ssible to replace the covering on the lower press roll while it is still on the machine. It is generally necessary to remove the entire roll and to ship it to the manufacturer thereof thus also necessitating considerable and costly shutdowns.

It has been stated, for example, in US. Patent L978,- 982, that many of the disadvantages inherent with perforated coated lower press rolls should be eliminated by employing an endless belt of, for example, rubber, which is provided with perforations therethrough. However, in paper-making machines traveling over 1200 feet per minute, even this lower press roll construction cannot utilize the full advantage of the suction due to the element of speed and the time element of the web and felt in the nip of the press rolls. Moreover, the lower suction press roll is a highly expensive piece of equipment. In the present invention, there is provided a relatively inexpensive lower press unit which may be used so as to eliminate the above-mentioned disadvantages and which may be efiectively and efficiently utilized without the need of suction or the like. This improved lower press unit comprises a plurality of rolls around which moves an endless belt of, for example, rubber or rubber-like material having .a plurality or profusion of holes or wells of predetermined depth on the outer surface thereof, that is, on the surface which comes into contact with the press felt as it is conveyed between the upper press roll and lower press unit. The holes may be of the same depth or of various depths, however, in no instance do they penetrate through to the bottom or inner surface of said belt. Provisions are made for guiding and tensioning the endless belt.

Much consideration has also been heretofore given to providing an upper press roll which had a hard, smooth surface, and which had a low coefilcient' of friction and substantially no alfinity for the paper fibers, in other words, it must not pick up paper fibers so as to spoil the web running under it. This sticking or picking action of paper fibers to the roll is cumulative so that eventually the surface becomes undesirably uneven and bumpy. Sticking of the paper fibers to the upper press roll may cause the paper to tear which may necessitate greases i9 rethreading the paper web through the machine, again with a considerable loss of time, money and production. Metal rolls for the most part can be provided with a straight or crowned, smooth, hard surface. However, generally such metal rolls possess the disadvantage of readily picking up paper fibers which, as pointed out, is undesirable. In the present invention there is provided a metallic upper press roll of a construction such that paper fibers can be prevented from being picked up thereby or from sticking thereto. The preferred upper press roll comprises a hollow roll or cylinder of suitably sintered metal having va predetermined porosity. This roll although having a porous surface which has little or no tendency to pick up paper fibers, is also easily provided with a smooth, hard, straight 'or crowned surface. Moreover, the present invention also contemplates the introduction of hot air or steam under suitable pressure into said roll, the hot air or steam then flowing or permeating through the porous sintered metal roll so as to force the paper web from the roll, thus minimizing picking problems. Furthermore, the heated upper press roll and the hot air or steam flowing therefrom Will also aid in water removal by vaporizing or evaporating water in the nip formed by the upper press roll and lower press unit. 7

Referring now to FIGURE 1 wherein. there is shown a porous press belt 10, generally of felt, conveying or carrying a water-'ladened paper web or sheet 12. The press felt 10 and the paper web 12 are advanced or propelled between the nip of an upper or top press roll or unit 14 and a lower or bottom press unit 16 for pressing or squeezing water from paper web 12. Although only one pair of vertical press units are shown, it should be understood that two, three or more of such press units may be utilized in a paper-making machine.

The upper press roll 14 preferably comprises an elongated hollow body or structure having at least its longitudinal wall 13 formed of a suitable thickness of sintered metal. The end walls 20 of the upper press roll 14 which need not be formed of sintered metal are provided with journals or shafts 22. The upper press roll 14 is mountedby its journals 22 in suitable supports or bearings (not shown). The choice of the type of metal or alloy employed in sintered form depends on the conditions of service. Among'the many metals or alloys 4 which may be utilized as the upper press roll in sintered 7 d the hollow center of the sintered metal roll 14 to create a hot surface to iron and help dry the paper web 12. 0bviously more water can be extracted from the paper web by employing elevated temperatures. One manner or means by which the hot air or stream from a suitable supply 40 can be injected is, for example, through a condit 42 in each of the roll journals 22. Preferably, the hot air or steam is injected into the upper press roll 14 under a suitable pressure so as to have the hot air or steam flow through the porous sintered metal roll and to vaporize or evaporate water in the nip formed by the upper press roll and lower press unit, thus helping to increase water removal. The elevated temperatures will also result in vaporizing or evaporating, to some extent, the water pressed into the holes of the belt, thus achieving more water removal. of steam or hot air pressure utilized will depend on the condition of service. It should also be noted that by forcing the steam or hot air through the porous sintered metal roll there should be provided a tendency to force the paper web from the roll thus helping to minimize any picking problem. Furthermore, such outward flow of hot air or steam should aid in maintaining the roll clean. The bottom press unit 16 comprises an endless belt, blanket, bolster or the like 24 and a plurality of predeterminedly spaced rolls over which belt 24 moves or travels. In order to support, guide and tension the. endless belt 24 a plurality of rolls are provided, four rolls 26, 28, and 32 being shown here. These rolls are suitably mounted or supported through their shafts.

Rolls

28 and 32, for the most part, hold the endless belt away from nip or press roll 26 but allow the curb less belt to come in contact with roll 26 at a point where it nips with the upper press roll 14. To insure that inner surface of endless belt 24 has sufficient frictional engagement with roll 26 so as to prevent slippage therebetween,

at least one of rolls 28, $0 and 32 may function as a tension roll, the others then functioning as idler or carryform, mention may be made of bronze, brass, stainless steel, mild steel, cast iron and the like. The degree of porosity in the sintered metal may be controlled. The use of an'upper press roll 14 of any particular degree of porosity will depend upon many factors such as, for example, the grade of paper being run and other operating conditions on the machine. The outer surface of, sintered metal wall 18 can be appropriately machined to provide the desired smooth, straight or crowned surface. It should be noted that the outer smooth surface of wall 18 contains a profusion of minute pores. however, are too small to mark or to leave any imprint upon the paper web 12. As pointed out above, the permanently porous surface which is achieved through the use of sintered metal has little or no tendency to pick up paper fibers in cases where the paper web comes into direct contact with its surface. This may be due to the trapping of air between the upper press roll and paper web which prevents any picking up or sticking of paper fibers.

The sintered .metal roll may be doctored with steel, Micarta, Monel (trademark of International Nickel Company for nickel-copper corrosion resistant alloys) or other similar type oscillating blades (not shown) in order to prevent wrapping of the upper press roll by the paper Web in the event of a break.

In one embodiment, means are provided to heat the sintered metal roll. Preferably a hot gas such as, for example, hot air or steam is injected or introduced into These pores,

ing rolls for the endless belt 24. As shown, upper press roll 14, roll 26 and roll 30 are invertical axial alignment while the spaced pair of rolls 2% and 32 are in horizontal axial alignment and predeterminedly positioned with respect to the vertically spaced rolls 26 and 30. At least one of

rolls

26, 28, 30 and 32, for example, roll 26 or 30, is driven in synchronism with the feed rolls of the press felt 10 so that the endless belt travels in the same direction and at the same speed as the press felt 10. 'It should be pointed out that the endless belt 24, and rolls associated therewith, as well as upper press roll 14, travel at high speeds so as to pass therebetween, paper web and press felt, at rates in excess of 1000 feet per minute. The

rolls

26, 28, 30 and 32 may be constructed of any of the well known suitable materials, such as brass, stainless steel and the like. The rolls, particularly roll 26, to provide less wear and thus increased life to endless belt 24, may have a suitable rubber covering therearound. Such rubber covering may also be employed on mild steel rolls to relieve the corrosion problem present.

The, endless belt 24 preferably comprises a relatively flexible or resilient material such as rubber or rubberlike material or other polymericmaterial. The choice of the endless belt material would depend upon the conditions of service such as types of paper to be run, type of machine, pressure, temperature, concentration of chemicals that might be'involved in the operation and the like. The belt preferably of rubber, may be manufactured endless on a mandrel, cured in a Vulcanizer or similar vessel and then suitably finished on the mandrel or after removal, or made as a belt, cured and then made endless by splicing the ends together. The endless belt may be manufactured with or without suitable reinforcement members. Thickness and hardness of the endless belt will depend on the type of paper machine, grades of paper, pressures and other operating condi tions. The thickness of the endless belt generally is on The amount the order of about one inch although a somewhat thinner or thicker belt may be utilized. The width of the end less belt would be at least equal to or slightly greater than the width of the paper web 12. Thus, in present commercial paper-making machines the width of the endless belt may range from about 50 to 300 inches or more. It should be mentioned that the upper press roll 14 and other rolls heretofore mentioned are preferably coextensive in width with the endless belt.

Circumferentially and widthwise, the endless belt 24- is provided on its outer or upper surface, that is, the surface which comes into contact with the press felt 10, with a plurality or profusion of holes or wells 34 of a depth which is less than the thickness of the belt. The holes 34 are preferably predeterminedly spaced to form a definite pattern. The pattern can be varied depending on the type of paper or paper board machine, grades of paper and other operating conditions. A definite pattern of holes is desirable for uniformity of water remaining in the paper web. The holes 34 will vary in diameter depending upon such factors as mentioned above. For example, under many operating conditions, hole diameters on the order of a sixteenth of an inch may be suitable. However, when pigments or the like are present in the web of paper, larger hole diameters, say on the order of an eighth of an inch or bigger, may be employed so as to prevent blocking or clogging of the holes by pigment or other material. It may also be possible to employ an endless belt having therein holes of different diameters. through the endless belt and may thus be termed blind holes may be of the same depth or they may be of various depths such as shown, for example, in FlGS. 3 and 4. It should be particularly noted that holes 34 do not penetrate completely through the endless belt 24. The holes 34 can be drilled into the surface of the belt or the holes can be moulded into belt or provided by some other suitable means.

The use of an endless belt of the above construction provides for a more generous or wider nip and hence the opportunity of filling up more holes with water as the belt is passed through the nip at a high speed. The water so pressed or entrapped in the holes while passing through the nip is thrown 0r spewed out by centrifugal force from the belt and thereby eliminated from the system. The blind holes in the endless belt also act as tiny reservoirs or wells of water in the area of the nip and the use of heat in the area of the nip will result, to some degree, in the vaporization or evaporation of water from these holes thus resulting in more or increased water removal. Moreover, the use of the preferred endless belt not only results in conditioning the press felt to carry its maximum capacity in respect to water removal but also permits increased felt life due to the softer more cushioned-like nip.

Referring now to FIG. 2 wherein like numbers refer to like elements of FIG. 1, there is shown in this case a web of paper 12 carried between a pair of press felts a and 1%. It is obvious that the use of two felts can be utilized with the apparatus of FIG. 1 and that the use of a single felt as shown in FIG. 1 can also be used with the apparatus of FIG. 2. The press felts 10a and 10b with the paper web 12 therebetween is advanced between the upper press roll 14 of a construction as heretofore described and a lower press unit 16. In this embodiment, the endless belt 24 travels around two vertically spaced apart rolls 26 and 36 which are also in axial alignment with upper press roll 14. Roll 30 may be employed for suitably tensioning the endless belt.

Roll

26 or 30 may be provided with means (not shown) for driving the endless belt in the same direction and at the same speed as the press felts. The construction of the endless belt and rolls 26 and 39 is as heretofore described.

The holes 34 which extend only partially The apparatus described above could be installed at one or more positions on a paper-making machine such as, for example, the main press section and hot press positions on a Fourdrinier paper machine, at the main press and primary presses on a Cylinder Machine and at the main press or in the pressure roll or drier position on a Yankee Fourdrinier.

In the preferred operation of the apparatus, as shown in the drawings, a paper 12, after it is formed in the Fourdrinier, is conveyed at a high speed by one or more press felts 10 between the upper press roll 14 and lower press unit 16. team or hot air under suitable pressure, for example, 20 to 25 pounds of steam is introduced into the hollow center of the sintered metal roll 14 to create a hot surface to iron and dry the paper web, particularly in the case where the roll comes into direct contact with the paper web such as shown in FIG. 1. When two felts with the paper web therebetween are employed such as illustrated in FIG. 2, the heated roll adds to the drying thereof in addition to the normal water removal by pressure. The steam or hot air is forced out through the porous roll and heats not only the paper web and felt in the nip but also the water which has been pressed or squeezed into the blind holes 34 carried by the endless belt 24. The use of such elevated temperatures aids in increasing water removal by vaporizing or evaporating Water in the nip including, to some extent, the vaporization or evaporation of water held or pressed into the small blind holes carried by the endless belt 24. Due to the porosity of the surface of upper press roll 14- it has little tendency to pick up paper fiber. The elimination of having paper fibers picked up and accumulated on the roll is furthered by the outward flow of hot air or steam from the roll which tends to force the paper Web away from the roll. Furthermore, the outward flow of hot air or steam from the upper press roll 14 also aids in maintaining the roll clean.

As the rapidly moving endless belt passes through the nip, water pressed and squeezed from the paper web and felt is entrapped or picked up in blind holes 34 and then thrown or spewed out by centrifugal force. The removal of water from the paper Web is thus achieved through a combination of pressure, squeezing, heat and centrifugal force.

Although the described improved upper and lower press units are preferably employed in combination, it should be pointed out that each press unit may be utilized in combination with a press roll of Well-known construction. For example, the improved upper press roll herein described may be employed in conjunction with heretofore well-known bottom press rolls such as, for example, suction press rolls or other conventional bottom press rolls. It should also be pointed out that the improved lower press unit having an endless belt provided with a profusion of blind holes on the outer surface thereof may be used in combination with well-known upper press rolls. For example, a conventional upper press roll constructed of a metal such as brass, bronze, stainless steel, mild steel or other metal or alloy, chrome-plated roll, granite, wood and the like could be employed with the preferred endless belt. The roll may be heated internally or as shown in FIG. 2, externally such as by jet of steam into the nip to elevate the temperature of the surface of the upper press roll and the endless belt. Suitable conduits 44 and jet means 46 can be utilized to provide a flow of hot gas into the nip. Although the use of such improved press units do provide an improved press when used in conjunction with well-known upper or lower press rolls, the preferred and most advantageous combination is when they are used together as shown in the drawings.

The press units of the present invention when used in a paper-making machine possess or achieve many significant advantages. For instance, the endless belt is not i suction press rolls.

* of the present invention also eliminates the need for exbonded to the lower press roll and thus, if the belt developed some imperfection or became worn from use, it could be removed and replaced without the major difficulty of removing the entire lower press roll or reconditioning the surface thereof. In many instances, the endless belt could be reconditioned while in use on the machine. Furthermore, since the endless belt is removable and replaceable it does not take the press out of service for any great length of time nor does it requ le the difiiculty and expense of removing the entire lower press roll and shipping it to the original manufacturer for repairs or recovery. Moreover, the endless belt eliminates the requirement for the special and expensive rubber to metal bonding now needed for rolls currently employed. Furthermore, there is eliminated the accurate and expensive drilling of holes in the rubber coverings utilized in lower Very significantly, the endless belt pensive suction boxes or means now used with the press rolls. Additionally, the endless belt enables the papermaking machine to beoperated at higher speeds and provides a greater surface within the nip or area of engagement of the press units where the water can pass from the paper web into the holes of the belt. Moreover, the life of the press felts can be increased considerably due to the more cushioned-like nip and thus felt costs can be reduced. Additionally, the improved press units improve water removal, permit lower steam costs per ton of paper or, board, improve finish of the paper web or sheet in cases Where the upper press roll comes in direct contact with the paper web, minimize what is generally known in the paper industry as picking, provide cleaner felts for longer periods of time due to the additional springor cushion-like action in the nip which has the desirable eifect of keeping the felts open, achieve less cost of overall maintenance, less replacement costs, less capital investment and lower cost per ton of paper or board.

Although the improved press rolls have been described in connection with a paper-making machine, it should be pointed out that such press units are also applicable to other machines such as of the type used, for example, in

the manufacture of asbestos or asbestos-cement products.

Since certain changes may be made in the above prod ucts or apparatus without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A press assembly for use in extracting liquid from a moving web of material comprising, in combination, an upper press unit and a lower press unit, said units defining a nip therebetween, said upper press unit comprising a hollow roll of sintered metal having a prede termined porosity and means for heating said roll at least in the area of and adjacent the nip, said lower press unit comprising an endless belt of a resilient ma terial and a plurality of rolls around which said endless belt travels, said endless belt having circumferentially and widthwise on the outer surface thereof a profusion of holes of a depth which is less than the thickness of said endless belt.

2. A press according to claim l wh'erein said endless belt comprises rubber.

3. A press assembly for use in extracting liquid from a moving web of material comprising, in combination, an upper press unit and a lower press'unit, said units defining anip therebetween, said upper press unit comprising a hollow roll of sintered metal having a predetermined porosity and means for supplying a hot gas under pressure into said roll to heat said roll and to provide a flow of hot gas through said roll, said lower press unit comprising'an endless belt of resilient material and a plurality of rolls around which said endless belt travels, said endless belt having circumferentially and widthwise on the outer surface thereof a profusion of predeterminedly spaced holes which extend only partially through said endless belt.

References Cited in the tile of this patent UNITED STATES PATENTS 1,722,503 Millspaugh July 30, 1929 1,978,982 Barstow Oct. 30, 1934 1,990,102 Smith Feb. 5, 1935 1,998,046 Ellis Apr. 16, 1935 2,167,544 De Bats et al July 25, 1939 2,209,759 Berry July 30, 1940 2,288,675 Berry July 7, 1942 2,997,406 Freeman et al Aug. 22, 1961 3,023,805 Walker Mar. 6, 1962 FOREIGN PATENTS 1,198,432 France June 15, 1959 568,264 Belgium June 30, 1958 720,165 Great Britain Dec. 15, 1954

Claims

1. A PRESS ASSEMBLY FOR USE IN EXTRACTING LIQUID FROM A MOVING WEB OF MATERIAL COMPRISING, IN COMBINATION, AN UPPER PRESS UNIT AND A LOWER PRESS UNIT, SAID UNITS DEFINING A NIP THEREBETWEEN, SAID UPPER PRESS UNIT COMPRISING A HOLLOW ROLL OF SINTERED METAL HAVING A PREDETEMINED POROSITY AND MEANS FOR HEATING SAID ROLL AT LEAST IN THE AREA OF AND ADJACENT THE NIP, SAID LOWER PRESS UNIT COMPRISING AN ENDLESS BELT OF A RESILIENT MATERIAL AND A PLURALITY OF ROLLS AROUND WHICH SAID ENDLESS BELT TRAVELS, SAID ENDLESS BELT HAVING CIRCUMFERENTIALLY AND WIDTHWISE ON THE OUTER SURFACE THEREOF A PROFUSION