US 2091805 A
Description (OCR text may contain errors)
H. A. CHUSE PAPER MAKING METHOD AND MACHINE Filed Oct. 6, 1934 5 Sheets-Sheet 1 a n a .o- .HQ. 0 G w o M kw o 1 u Ma N Aug. 31, 1937. H. A. CHUSE 2,091,805 PAPER MAKING METHOD AND MACHINE I Filed Oct. 6, 1934 5 Sheets-Sheet 2 for i W i W5 7 M W.
Q N x E QM Aug. 31, 1937.
H. A. CHUSE PAPER MAKING METHOD AND MACHINE Filed Oct. 6, 1954 5 Sheets-Sheet 3 NWE M e JMLL Aug. 31, 1937. H. A. 'CHUSE PAPER MAKING METHOD AND MACHINE Filed 001;. 6, 1934 5, Sheets-Sheet, 4
5 Sheets-sheet 5 H. A. CHUSE PAPER MAKING METHOD AND MACHINE Filed Oct. 6, 1934 OOOOOOOOGG Jid/ iv 2 v 7 0 7a? 7. (we: MM )au w? mmN Aug. 31, 1937.
. WMN MMN NWN Patented Aug. 31, 1937 UNITED STATES PATENT OFFICE Application October 6,
This invention, relating to paper making methods and machines, is concerned particularly with the procedure and equipment employed subsequent to the making of the wet sheet; the objects of the invention being to provide an improved method and means for drying paper in the process of manufacture in a'continuous'sheet, and to provide an improved method and means for the entire procedure to which the paper sheet is subjected after its removal from the medium on which it is formed. In a general sense the invention may be regarded as providing a novel paper making method and machine as a whole, though not involving novelty with respect to the making of the wet sheet.
The process of making paper in a continuous sheet involves progressive removal of water from the formed sheet by the action of a succession of agencies. On a Fourdrinier paper-making machine, for example, the removal of water from the paper sheet begins while the sheet is still on the making wire, much water being removed by draining through the wire, some water being displaced from the sheet by the action of the flat suction boxes across which the wire slides, and an additional percentage ofwater being forced from the sheet-by the action of the suction couch roll at the delivery end of the wire. However, after the sheet. has formed with accompanying drain- 30 age of its surplus water by gravity and table roll action, the water contained in the sheet is so tenaciously held that only a limited reduction of the water content of the sheet can be accomplished by the action of the flat suction boxes and the suction couch rell. Ordinarily when the wet sheet leaves the making wire, or after it has passed the suction couch roll, it will be only about or less dry, or in other words will contain 80% or more of water, depending upon the thickness or the sheet, the stock from which it is formed, the speed at which it is made and the efiiciency of the flat suction boxes and suction couch roll to reduce the moisture content of the particular sheet made at the particular speed.
Thus the wet paper sheet delivered from a Fourdrinier making wire or other medium on which the sheet is formed is composed of a relatively large proportion of water and a relatively small proportion of paper material, by weight,
the percentage of water contained in the sheet being, as above stated, ordinarily about 80% or more. This great amount of water or most of it must be removed from the sheet by subsequent r operations to reduce the sheet to the relatively low moisture content desired for the calendering 1934, Serial No. 747,175
ing wire or medium on which it is formed and the calendaring operation, the conventional method which for many years has been and is now employed involves the expressing or squeezing out of a certain proportion of the water from the wet sheet by the action of a series of presses,
which requires the carrying of the wet sheet on moisture absorbing press felts through the first and second presses and sometimes through the third press; and the drying of the sheet after pressing by carrying the sheet around or in contact with a series of ordinary driers consisting i of revolving steam heated cylinders which heat the paper and cause its drying by evaporation, the evaporated moisture being carried oil. by ventilation.
As the paper cannot be produced any faster than it can be delivered in sufficiently dry state for the calendering operation, the capacity of ordinary drying equipment required for a paper making machine will depend upon the speed at which the paper made on such machine is formed and delivered to the driers, and upon the amount of water contained in the sheet when it is delivered to the driers, wherefore it has been considered advisable to remove by pressing or by pressing and supplemental agencies as much water as it is practicable to remove from the sheet in this manner before the sheet is delivered to the driers. The modern high speed Fourdrinier paper making machine of conventional character has therefore elaborate press and press felt equipment, and extensive drying equipment to provide the drying capacity required for drying the paper as fast as it is delivered from the Fourdrinier making wire or other medium on which the sheet is formed.
Now the press section of a paper making machine, besides comprising elaborate and cumbersome equipment occupying a considerable amount of space, has always been and is a troublesome part of the machinery, due among other causes to the difficulty of running the paper through the presses without breakage or without injuring the paper or by crushing effects. The speed at which paper can be produced on conventional machines is primarily limited not only by the rate at which it can be formed on the table but also by the speed at which it can be run through the presses without injury and then dried for calendering. Modern improvements in the Fourdrinier including particularly the sliction couch roll, and the use of long press felts of good quality and other improvements in connection with the presses including particularly suction press rolls, have made it possible to pro duce ordinary news print paper at speeds ranging up to 1,000 ft. per minute and over. Nevertheless the press section of the Fourdrinier remains a troublesome factor and is believed to impose a speed limitation without which it might be possible in the future to attain substantially higher speeds in paper production than are now feasible.
Moreover the press section of the paper machine requires constant attention, the maintenance of the press felts in cleansed condition, and the frequent removal and replacement of press felts, with consequent expense. Furthermore the amount of water which can be removed from the sheet by pressing, or by the use of a series of heavy presses in conjunction with press felts, is quite limited. Ordinarily the sheet after it leaves the third or last press of the paper making machine will contain about 65% or more of water, which large amount of water except the low percentage desired to be retained in the finished product must be removed by drying, requiring consequent extensive drying equipment where the conventional method of drying is employed.
The present invention contemplates a radical departure from conventional paper making methods and machines with respect'both to the drying and drying equipment in the ordinary sense and the entire procedure between the stages of delivery of the wet sheet from the-Fourdrinier making wire or other medium on which it is formed and the calendering of the sheet. The invention provides for drying the sheet in such manner as not only to give requisite drying capacity for a high speed paper making machine with much less extensive equipment than if ordinary driers were used, but also in such manner as to dry the sheet advantageously and economically without preliminarily removing water from the sheet by pressing, and yet with substantially less extensive equipment than the ordinary drying equipment required after the sheet has been subjectedto the usual pressing operation. Thus the invention contemplates omission of the step of removing water fromthe sheet by pressing,
thereby'eliminating the elaborate, cumbersome and costly press and press felt equipment with all of its diificulties and objections. On the other hand, pressing the. sheet while sufiiciently moist to be'compacted and smoothed by the pressing is desirable, and the invention contemplates retaining a limited pressing operation preferably performed by a single pair of press rollsoperating on the bare paper sheet at a stage of the drying operation after the sheet is too dry for expressing moisture of for injury by the pressing operation. Preferably the pressing is done when the sheet is about from 70 to 80% dry, or in other words when the moisture content of the sheet is reduced tofrom about 20% to 30%, it having been fiber strength to conduct the pressing'operation when the sheet has been reduced'to such a rela-- the drying of the paper principally or mainly found most advantageous from the standpoint of,
- next suction drier.
before pressing, and the reduction of the pressing operation to a compacting and smoothing operation at an intermediate stage in the drying operation, preferably by the use of a single press,
after the sheet is of too low a moisture content of the invention in connection with the said drying methods and equipment, are susceptible of general utility in the paper making industry, or in other words that the drying methods and equipment embodying the present invention or features thereof are intended to replace present methods of drying in paper manufacture, whether with or without preliminary removal of water from the paper sheet by pressing or by pressing and other agencies before delivery of the sheet to said drying equipment.
For the paper drying process, the invention utilizes extensively the property of air to absorb moisture with which it is brought into intimate contact. According to the invention, the drying process involves successively forcing large volumes of air through the paper sheet, under conditions promoting vaporization of the moisture in the sheet and the absorption and carrying off of the moisture by the air passing therethrough. In carrying out the invention the paper sheet delivered from the making wire may be entrained about a series of revolving closely perforated cylinders, the air being forced through the paper and the perforations in the cylinders. The forcing of the air through the paper may be induced by external air pressure or by suction within the cylinders or by a combination of both. As the most expedient and practicable system, suction within the cylinders is employed. The said cylinders may consist of the perforated shells of suction rolls of appropriate construction to provide extensive suction areas to be sealed by the paper sheet entrained about the cylinders. For convenience such cylinders are herein referred to as suction driers to distinguish from the ordinary driers which merely heat the paper sheet to cause evaporation of moisture.
The process of drying the paper by forcing air therethrough can be hastened and can be ac complished with a smaller use of air than would otherwise be needed by heating the air considerably and heating the paper sheet occasionally or in alternation with the forcing of the heated air therethrough. The process of evaporation by air circulating in intimate contact with the moisture in the sheet has a cooling effect notwithstanding that the air forced through the sheet is in a heated state. It is therefore highly advantageous to heat the paper sheet occasionally or in alternation with the serving proper heat balance for full rnoisture saturation of the heated air passing through the sheet. It will be understood that the volume of heated air which passes through the paper sheet on any suction drier absorbs and carries oif a certain proportion of moisture/in the sheet, but with a cooling effect as above noted, which without. succeeding heating of the sheet would reduce the moisture absorbing effect of the volume of heated air passed through the sheet on the By carrying the sheet around ordinary driers in alternation with the suction driers, the desired heat balance between the sheet and the heated air to be forced therethrough is restored. The heat imparted to the sheet by the ordinary driers promotes rapid vaporization of the moisture in the sheet and full moisture saturation of the air successively passed through the sheet.
On ordinary paper machines the ideal temperature of the paper is from five to ten degrees below the temperature of the steam heated driers, and it remains constant. By a system of drying the paper by carrying it alternately around ordinary driers and suction driers, the
paper leaves a. heated drier at about the same temperature as in ordinary practice but under the evaporation process in the succeeding suction drier or driers it may cool 100 or more by the time it reaches the next reheating drier;
hence the average temperature range will produce a flow of heat from the heated drier to the paper of five or six times the rate possible with the old method.
With ordinary methods of drying, there is considerable diificulty in drying the paper to the narrow limit desired by the trade. If the paper contains too much moisture it will not print well.
If delivered too dry, there is a loss in desired weight and the calendering is not so effective 0 nor will the paper print as easily as if properly calendered. The invention contemplates therefore drying the paper to a higher degree than is desired for calendering, and then conditioning the paper for calendering by forcing moisture laden air through the paper just before it is calendered.
Other method and mechanical features of the invention will be apparent from the following description of certain methods and machines embodying the invention, reference being had to the accompanying drawings in which:
Fig. 1 is a diagrammatic view of a paper making machine of one practicable construction embodying and for practicing a method embodying 5 the invention.
Fig. 2 is an enlarged view of the first section of the drying equipment of said machine.
Fig. 3 is an enlarged view of the second section of said drying equipment.
tion of said drying equipment.
Fig. 5 is a crosssection through one of the drying sections and condensing apparatus as sociated therewith.
Fig. 6 is a diagrammatic view of a modified machine embodying features of the invention.
Fig. 7 is an enlarged view of the second section (Faii thg drying equipment of the machine shown in Fig. 9 is a view partly in end elevation and. partly in cross section of said suction drier.
Fig. 10 is an end view of blocking oif means of a suction drier.
Fig. 11 is an enlarged detail view of the blocking ofi means shown in Fig. 9.
The specific machine selected for illustration will now be particularly described, it being understood that the following description thereof is to be taken asexplanatory and not as limiting the. invention which is hereinafter set forth in the claims.
In Fig. 1, the reference numeral l designates the making wire of a high speed Fourdrinier paper making machine. The wet section 'of the ma- Fig. 4 is an enlarged view of'the third sec- Fig. 8 is a longitudinal section of a suction drierchine, represented by the making wire, will be understood as including all approved equipment necessary or desirable in connection with the making of the wet sheet, including liquid stock supplying apparatus, the breast roll, table rolls, deckles, dandy roll, fiat suction boxes and other accessories employed in modern high speed Fourdriniers. The making wire at its delivery end is entrained on a suction couch roll 2 whereby the wet paper sheet which forms on the making wire, after submission to the action of the flat suction boxes, is subjected over the suction couch roll to a constant high tension vacuum action with a resultant consolidating and moisture reducing efiect such that the paper sheet is made in a relative firm and intact condition, though containing, as before indicated, usually about per cent or more of water. The wet sheet made on the machine is designated by the numeral 3.
The machine represented in Fig. 1 comprises the Fourdrinier wet section, herein represented by the making wire, drying equipment which in this instance is in three sections, a single press 4 located between the second and third sections of the drying equipment, andcalenders 5; there being no press section in the ordinary sense of equipment for pressing water from the paper sheet preparatory to drying.
The drying equipment, shown more clearly in Figs. 2, 3, and 4, comprises in this instance a series of driers numbered 6 to 29, inclusive, including suction driers numbered 1, 9, ll, I3, l5, l1, [9, 2|, 23, 24, 26, 27, 28, and ordinary driers numbered 6, 8, l0, l2, l4, l6, i8, 20, 22, 25. sheet is carried successively around the driers in the order in which they are numbered. With the particular arrangement shown, the paper sheetis carried alternately around suction and ordinary driers in the first and *second sections of the drier equipment (Figs. 2 and 3), and in the third section is carried alternately around ordinary and suction driers and then, around a succession of suction driers 26, 21, 2B and then around a conditioning unit 29 which is similar to the suction driers but is employed in this instance for forcing moisture laden air to the dry paper sheet preparatory to calendaring.
Each suction drier comprises a revolving cylinder in the form of a closely perforated metal shell 30 having closed ends and containing alarge perforated suction pipe 3| in connection with suitable vacuum pumping apparatus (not shown) The paper whereby to maintain sufflcient suction or vacuum action within the cylinder to cause the forcing of air from the exterior of .thepylinder through the paper sheet entrained thereon. The major portion of the cylindric area of such suction drier is sealed or covered by the paper sheet passing around or about the drier, while the small segment which is not covered by the paper sheet is blocked on by means indicated atv 32 in Figs. 2 to 4 to prevent the ingress of air through the perforated area not covered by the sheet, whereby to cause all air drawn into the cylinder topass through the paper. Each cylinder may be covered or jacketed by a wire cloth jacket 33 (Figs. 8 and.9) to avoid any possibility of water marking or other marking of the sheet by the perforated pattern of the shell.
As before stated, the drying system in th illustrated machine is arranged in three sections respectively shown in Figs. 2, 3, and 4. Each drying section comprises a number of said suction driers and-of said ordinary driers, together with suitable carrying means for carrying the paper sheet successively around the driers or with carrying and holding means for-carrying the sheet around certain of the driers and for holding them in cooperative relation with certain of the other driers, which carrying means or carrying and holding means are represented by the drier felts'hereinafter referred to, though in some instances and particularly in the manufacture of paper heavier and denser than ordinary newsprint the drier felts or certain of them may be replaced by wire cloth aprons.
nection with a source of warm or preheated air, and contain air drying or air heating equipment, such for example as steam heating coils. All steam heating coils in the several drier sections are designated by the numeral 34.
The first drier section (Fig. 2) which receives the wet paper sheet from the Fourdrinier making wire, and in which the most elementary stage of the drying is performed, comprises the ordinary driers 6, 8, l0, l2 and suction driers T, 9, ll, I3 arranged in alternation therewith, and the coacting felts 35 and 3B which receive the paper sheet between them and carry the sheet successively substantially surrounding the respective areas of the suction driers which are entrained by the felts and paper sheet carried thereby. As shown,
the wet paper sheet 3 delivered from the Fourdrinier making wire. is deposited upon the felt 35 which carries the sheet through the guide opening 42 into the housing and travels around the guide roll 38 whereby the sheet is brought into contactwith the coacting-felt 36 and the two felts carrying the sheetbetween them travel successively around the driers. The sheet passes from the last drier l3 under the guide roll 43 and out from the housing for delivery to the next section of the drying equipment. In the particular construction shown in Fig. 2, the housing opening through which the paper sheet emerges is substantially closed by the drier-I3 and guide roll 43. Guide openings in the housing for the return run of the lowerfelt 3? are indicated at 4%.
With the illustrative arrangement of the felts 35 and 35 of the first drier section, one of said felts is inside the paper and the other felt is outside as the paper is carried around the driers. This arrangement is advantageous for the first stage of the drying paper sheet in the relatively wet condition in which it is received from the Fourdrinier making wire. It protects the freshly made wet paper sheet from the sudden heat of thefirst driers, thus protecting the sheet from tendency to burn to the driers. It passes the paper sheet from drier to drier, will deliver all broke for removal as hereinafter described, and
The driers of. each section are enclosed by a housing in cona drier section, whereby the moisture content of the sheet is reduced below that obtainable by use of the ordinary elaborate press and press felt equipment, so that the sheet delivered from said first drier section will be substantially dryer than when delivered to the drying equipment of a paper making machine having conventional press and drier equipment.
The -.second drier section (Fig. 3) comprises the suction driers l5, l1, l9, 2| and ordinary driers I4, I6, [8, arranged in alternation with said suction driers, a felt 45 which travels successively around all of the driers, and a felt 46 which cooperates with the suction driers to assist in passing the paper sheet and in holding the sheet to said suction driers, said felt 46 being arranged for short are contact with the sheet on said suction driers. The housing for the second drier section is designated by the numeral 41, and the warm air inlet by the numeral 48. Guide openings forthe felt 45 are indicated at 49. Guide rolls at the paper inlet and outlet ends of the drier are indicated at 50 and 5|; other guide rolls for the felts at 52, and adjustable take-up rolls for tensioning the felts at 53. Within the drier housing 41 are steam coils 34 arranged in association with the suction driers in the same manner as already described. g
The paper sheet delivered from the first drier section is deposited upon the felt 45 and follows the same route as said felt throughthe second drier section, passing with the felt into the drier housing 41 and over the guide roll 50 and then successively around all the driers and then passing with said felt under the guide roll 5| and out from the drier housing.
With the arrangement of 'felts employed in the second drier section, the paper sheet passing through said section is inside the felt 45 as it goes around the ordinary driers l4, Hi, It, 20,
so that the paper sheet is carried in direct contact with said ordinary driers or steam heated cylinders as is now desirable for efiicient heating ,of and rapid evaporation of moisture from the partly dried sheet. On the suction driers l5, l1, I9, the felt 45 is on the inside of the paper sheet as before to protect the paper. The small contact of the other felt 46 presents less obstruction for the passage of air through the paper sheet than does the ordinary arrangement.
As the sheet is delivered to the second drier section in a partially dried state and without having undergone the compressive action of presses, the forcing of heated air through the sheet is very effective in the second drier section, and by this action in alternation with the heating ,of the sheet on steam heated drying cylinders or ordinary driers the sheet in passing through said second section is further dried in an advantageous manner, and may-be rendered as dry as or dryer than after having passed through threefourths of ordinary drying equipment.
In both the first and second drier sections,
the feltsmust have a very beneficial effect in moisture and surrendering it to the warm air through which the felts are continually passing. This feature is especially strong in the first drier section. The two felts can hardly fail to reach the paper except-in dry and hot condition. These two dry and hot felts pressed one on each side of the wet sheet of paper will instantly take up a large percentage of its moisture which will be removed from the felts by evaporation on the return runs of the felts.
The function 'of the first and second drier sections is to dry the paper sufficiently to bring it to an advantageous state of dryness for pressing. As before indicated, it is desirable to avoid pressing while the paper sheet is relatively wet, and to press the paper for compacting and smoothing effect after its moisture content has been reduced to from about 30% to almost 20%. Probably the most advantageous moisture content of the paper sheet for pressing is about or near to 20%. It is contemplated therefore that the capacity of the first and second drier sectionsshall be such that the paper sheet delivered from the seconddrier shall be between 70% and 80% dry, preferably about or near 80% dry. After delivery from the second drier section, the paper sheet runs through the single press 4 for compacting and smoothing, and is then delivered to the third drier section for further drying preparatory to calendering.
The third drier section comprises the ordinary driers 22 and 25, suction driers 23 and 24 in alternation therewith, additional suction driers 26, 27, 28 and conditioning unit 29, a felt 54 arranged to cooperate with the lower tier of driers Z2, 24, 2B, 28, and'a short felt 55 arranged to cooperate with the one ordinary drier 25 of the upper tier of driers. The felt 54 is held in cooperative relation to the lower tier of driers by the guide rolls 56, while the return run of said felt is engaged by guide rolls and the adjustable take-up roll 58 for tensioning the felt. Guide rolls for the short felt 54 are indicated at 59.
The housing for the third drier section is num- Some of the steam coils in the housing 60 are also arranged in proximity to the surfaces of the ordinary driers 22 and 25 which are engaged by the paper sheet and felts.
In the third drier section the paper sheet is covered by the felt 54 on the ordinary drier,22 and by'the short felt 55 on the ordinary drier 25, but is carried around the suction driers free of felts except for the short contacts of the felt 54' on the suction driers 24, 26, 28. As the paper sheet passes through the third drier section, the drying of the sheet is continued, first by the alternate action of ordinary driers and suction driers, and then by the continued forcing of heated air through the sheet on the suction driers 26, 21, 28, whereby the paper sheet is rendered sufiiciently dry for calendering or, in this instance, dryer than desired for calendering.
Because of the difficulty of drying paper to the narrow limits desired by the paper trade, the illustrative machine is designed to dry the paper continuously too dry and then to condition the Within the drier housing 60 are" paper for calendering by passing moisture laden air through the sheet, utilizing for this purpose the roll 29 which is similar to the suction driers. As shown in Fig. 4, the conditioning unit 29 is contained in a separate compartment of the drier housing, which separate compartment is formed by the partition 64. Warm moist air enters said compartment through the inlet openings 65 and is drawn through the paper sheet on the unit 29, conditioning the paper for calendering. Water coils 66 may be arranged in said compartment for cooling the warm moist air entering the same .to a predetermined temperature which may be kept constant by a suitable temperature control (not shown) which admits just enough cooling water to do this. The air having a constant temperature will have a constant ca-* pacity for moisture as any excess of moisture in the entering air will be condensed and carried out by the drip collector 61. Since paper has a great affinity for moisture if subjected to moisture laden air, it will draw moisture from the saturated air which is passed through it. This absorption will depend upon the relative humidity of the air, kept constant as above indicated, and the time of exposure. The time of exposure is kept constant as it is the time required for the paper to pass overthe suction unit 29. Hence, paper at or near. the desired final moisture. content will be tempered to very close limits by properly governing the temperature of the saturated air passed through it. The amount of absorption of moist air by the paper could also be controlled in otherways as for example by the method hereinafter explained with reference to Figs. 6' and 7.
In threading the paper sheet through the drying apparatus, the sheet is carried through the first drier section by the coacting belts 35 and 36. It may be threaded through the second drier section by means of an ordinary Shehan carrier (not shown). However it is possible to thread the paper sheet through the second section by means of the felt 45 with the assistance of air jets presently to be referred to and with the assistance of the top felt 46. For threading the other suitable source from a series of pipes 68 located within said suction drier. The broken sheet may be caught on the broke catcher 69 and discharged through an opening normally closed by the door 10. In, the second drier section (Fig. 3), a number of air nozzles H are arranged to discharge jets of air against the sheet in directions to hold it against the suction driers as the sheet passes thereto from the ordinary driers. Hence any broke will be carried around an ordinary drier by the felt 45, and thence to the next suction drier by the said felt withthe assistance of the air jets discharged at H, and over said suction drier by the top felt 46 cooperating with the lower felt; and after the broken sheet passes from the felt 46 the suction within the suction drier will cause the sheet to hug to the felt .45 and be carried thereby to the next ordinary drier. Thus broke will be delivered in the second drier section to the last drier 2|, from which it may be blown off by air blowing from pipes '12. The broken sheet may be caught on the broke catcher I3 and dis- 5 charged through an opening normally closed by the door 14. In the third drier section, nozzles are arranged to discharge jets of air toward the receiving sides of the several suction driers. Additional nozzles I6 near the off-bearing side of the drier 22 are arranged to discharge air downwardly. The several suction driers are provided with air pipes H for blowing the paper sheet from the ofi-bearing sides of said driers. The suction driers 24, 26, 28 in the lower tier of driers are provided with additional air pipes 18 arranged to blow air from the receiving sides of said driers. If a break occurs on the first drier 22, the broke will be blown from the ofi-bearing side of said drier by the nozzles and will be car- 20 ried' by the felt 54 under the lower tier of driers, the air discharged by the pipes 18 preventing the broke from ascending the receiving side of any of the driers 24, 26, 28. If the break occurs on the suction drier 23, the air jets discharged by the nozzles 15 associated with this drier will hold the sheet to its receiving side and the suction within the drier will hold it to its off-bearing side, and the broke will be blown off by the air blowing from pipes 11 in said drier and will be held to the next drier 24 by the air jets discharged from nozzles 15 associated therewith. Thus the broke will be caught on the felt 54, and will be prevented from ascending the receiving 3? side of any of the suction driers 24, 26, 28 by the discharge of air from pipes 18. 'If'broke occurs at any subsequent stage in the third drier section, the mode of handling it will be obvious. Nozzles I9 near the off-bearing side of the drier 28 are arranged to discharge air downwardly to 40 assist in discharging broke over the slide 80 iglgirough an opening normally closed by the door The blow-off pipes 68 in the last drier of the first drier section, the corresponding blow-off pipes 12 in the last drier of I the second section, the nozzles ll of said second section, the nozzles l5, l6 and 15 of the third section, and the blowoff pipes TE and 18 of the suction driers of said last section, are used respectively only to assist 0 in carrying the sheet when it is being threaded through the machine, or to carry broke. These several nozzles and blow-off pipes may be connected through separate valve-controlled connections (not shown) with any suitable source of compressed air, so that the air can be turned on for use when and if required, and shut off during the normal use of the machine.
The sheet metal-casings or housings containing the drier sections are constructed with numerous doors to permit access to the driers, felts and paper. As shown in Figs. 2 to 4, the drier housings are constructed with various doors or hinge sections in the top, ends and bottom. Various other doors or hinge sections are provided in the .sides of the housings.
It is desirable to provide for recovery and utilization of the large amount of heat that is contained in'the air and moisture discharged from the various suction driers, and particularly from those of the first drier section which removes from the wet paper sheet by evaporation water that is ordinarily pressed out and which uses a relatively large amount of heat. Reference will now be made. to provision for such hea I QOV 'Y- As shown in Fig. 5, the suction driers of the first drier section are connected to vacuum-pumping apparatus (not shown) through a counterfiow heat intercharger comprising a casing 82 having inlet and outlet chambers 83 and 84 connected by a series of condenser tubes 85. The inlet chamber 83 is connected by the piping 86 with the suction pipes in the suction driers, and the outlet chamber 84 is connected by the pipe 81 with the vacuum-pumping apparatus. The tubes extend. through an intermediate chamber 88 through which is drawn the air that is supplied to the first drier section. The air to be so supplied is drawn from the fresh air duct 89 and discharges through the outlet duct 90 either direct to the housing of the first drier section or to an intermediate apparatus for further pre-heating the air. The fresh air thus drawn through the heat intercharger condenses about 90% of the moisture in the air discharged from the suction driers, thus heating such air and recovering a large amount of heat that. would otherwise be wasted} while the moisture condensed in the tubes 85 may be drawn off through the hot water outlet 9| and may be used again as hot as desired in the white water supplied for making the pulp solution to be used on the wet section of the machine or may be used as boiler feed water.
Each section of the drier may be equipped with similar heat recovery apparatus, or the entire series of suction driers may be connected with similar apparatus of sufficiently large capacity to recover the heat in the air and moisture discharged from all the suction driers.
The air supplied to the drier sections is thus preheated by the heat discharged from said sections, with accompanying condensation of the water discharged from said sections. The condensed hot water can be used as boiler feed water. white water or for heating .purposes. Thus the actual consumption of heat in the drying process is materially reduced". The preheated air supplied to the drier sections may be further preheated by passing over steam coils supplied with exhaust steam from the engine or bleeder turbine. In the drier sections the air is further kcheated by steam coils 34, in which some. live steam may advantageously be used, though it is intended to use principally exhaust steam in the coils 34 as well as in the ordinary driers or steam heated drying cylinders.
The hot moist air supplied to the conditioning unit 29 may be derived from any suitable source; for example the suction pipe of an individual suction drier in the first drier section may be connected with the inlets 65 01 the chamber in which the conditioning unit 29 is situated, so that the conditioning unit will draw the. supply of moist air from such drier.
The drying equipment described with reference to Figs. 1 to 5 is in accordance with a construction and arrangement of drying equipment which has been designed for a machine for high speed production of newsprintpaper. It will be understood that said equipment may be variously modified as to the number of drying sections, the number and arrangement of suction driers and ordinary driers in the respective sections, and as to various details, to suit various different conditions and requirements. It is contemplated for example that wires may be used in place of some or all of the felts, that some of the felts may be omitted, or others added, and that drying systems embodying features of the invention may omit all felts or wires for carrying or holding the paper sheet.
The wet section of .the illustrative machine represented by' the Fourdrinier making wire I typifies any suitable wet section. The wire I typifies any suitable medium on which the wet paper sheet is formed or any suitable carrying medium to which the sheet is transferred from the surface on which it is formed.
Reference will now be made to Figs. 6 and 7, which represent a machine embodying features of the invention and adapted for conditions in which the sheet of paper or paper material can be dried for pressing with less drying capacity than that of the machine first described. The machine of Figs. 6 and '7 is in accordance with a con struction designed especially for manufacture of bulky or loose paper such as blotter and the like. It would also be suitable for drying pulp sheets if the press were omitted.
The wet section of the machine shown in Figs. 6 and '7 is represented by a Fourdrinier making wire I 00 entrained at its delivery end on a suction couch roll I M tions I02 and I03, a press I04 between the two drier sections, and calenders I05.
The first drier section I02 comprises a series of suction driers I06 and cooperating felts or wires I01 and I08 by and between which the paper sheet I09 is carried successively around said suc-' tion driers. Said drier section is enclosed by a housing similar to the housing previously described, and contains steam heating coils IIO.
The sheet in passing through said section is dried 30 by the forcing of the heated air through the sheet,
'together with the drying effected by the hot felts and the heat radiated to the sheet from the heating coils.
The second drier section I03 comprises ordinary 4O driers I I I, suction driers I I2, a felt I I3 which cooperates with the lower tier of driers, and a short top felt II4 cooperating with the one ordinary drier in the upper tier. This second drier section is substantially similar in all respects to the last drier section of the machine shown in Fig. 1, except that in the machine of Figs. 6 and 7 a different means is provided for conditioning the sheet for calendering. In the machine of Figs. 6 and 7, the paper sheet passes successively around the driers and from the last drier passes around guide rolls H5 and H6. Moist air for conditioning the sheet is drawn through the sheet on a segment of the last suction drier. The moist air is drawn from a suitable source of supply into the inlet chamber Ill and flows from said chamber through the passage II8 to the hood II9 from which the moist air is drawn through the sheet by the suction in the last suction drier. The passage H8 is controlled by the rotary valve I20 operated by the lever arm I 2i. The lever arm HI is pivotally connected to and suspended from link I23, the last mentioned link being pivoted to the drier housingat I24. Link I22 is pivotally connected to the long arm I25 of a bell crank lever whichis fulcrumed at I26 and the short arm I21 of which carries an adjustably mounted weight I28. Another weight I29 is adjustably mounted on the arm I25 of the bell crank lever. The arm I25 of the bell crank lever carriesa roller 30 held against the paper sheet between the guide rollers H5 and H6. The weights I28 and I29 are so adjusted that the roller I30 bears against the paper sheet. When the paper sheet taut the parts are in the position shown in Fig. 7, the valve I20 being open. If the paper The machine has two drier secsheet receives too much moisture, the sheet will stretch between the rollers H5 and H6, allowing the roller to move toward the right and close or partially close the rotary valve I 20, thereby regulating the amountv of moist air that can be drawn through the sheet from the hood II9.
Reference will now be made to Figs. 8 and.9, illustrating one practicable construction for a suction drier. As before stated, the reference numeral 30 designates the perforated shell of the drier, 3| the perforated suction pipe therein, 32 the means for blocking off the segment of the shell which is not sealed by the paper sheet, and 33 the wire cloth jacket on the sheet.
In the specific construction shown, the shell 30 is rigidly attached to heads I3I and I32. The suction pipe I3I has at one end a tubular extension I33 extending through the head I3I and secured in the hearing or support. I34. The head I3I is rotatably mounted on the extension I33 by the bearing I35. The suction pipe communicates with the vacuum-pumping apparatus (not shown) through the passage I36 in the support I34 registering with an opening in the suction pipe extension I33 which is closed at its outer end. At its opposite end the suction pipe has a projecting trunnion I3'I on which the head I32 is rotatably mounted through the bearing I38. Said head I32 has an extended journal portion I39 journalled on the fixed bearing I40.
As shown in Fig. 9, the suction pipe 3| is constructed with a projecting member of T-shaped cross section comprising the radial web MI and segmental web I42 connected with the end sectorshaped webs I43 and tn'aced'by intermediate sector-shaped webs I44. Attached to the segmental web I42 are side members I45 and segmental end members I46 which are preferably very nearly but not in actual bearing contact with the interior of the perforated shell 30. The construc tion referred to including especially the web I 42 carried by the suction pipe and the side members I45 and end members I 40 attached thereto constitute the blocking ofi means which has been referred to as a whole by the numeral 32.
It is desirable to avoid rubbing contact between the blocking off means and the interior surfaces of the revolving perforated shell, since there would be no adequate means of lubricating these surfaces if in rubbing contact. Hence it is desirable to'maintain a slight clearance of from .001" to .003? between the interior surface of the shell and the adjacent surfaces of the members I45 and I 46. The members I 45 are attached to the flanged or enlarged sides of the segmental web I42 by bolts I41 passing through short slots in said members. Adjusting screws I48 passing through the extensions I49 of the flanged sides of the web I42 bear against the members I 45. By adjusting the screws I48 the members I45 may be moved as closely as desired to the inner surface of the rotating shell, and the screws I41 may then be tightened to fasten said members in place. The screws I48 are provided with lock nuts I50. Theend members I46 are adjustably secured to the ends of the web I42 by fastening screws I5I passing through short radial slots in said members.
In making newsprint paper, and various other papers having considerable porosity, large volumes of air can be drawn through the paper sheet on the suction driers With the use of a comparatively low vacuum, so that the leakage of air which will take place through the very slight clearances between the members I45, I46 and incomposition or be provided with packing strips of special metal or composition to reduce the friction.
Within the suction pipe 3| are pipes I52 and H53 connected through valve-controlled connections (not shown) with any suitable source of compressed air, andfrom which respectively extend the blow-01f pipes I54 and I55. The blow- .oif pipes I54 correspond to the blow-off pipes IT in Fig. 4, and the blow-off pipes I55 correspond to the pipes-B8 in Fig. 3 and I8 in Fig. 4. 1
All of the suction driers may be of the construction described or other suitable construction. The illustrative construction of the suction drier is included as a feature of this invention, but the invention in other aspects is not limited to any specific construction of the suction drier.
Besides eliminating ordinary press and press felt equipment and all the objections incident thereto, the present invention makes possible a very substantial reduction in drying equipment, as compared with ordinary drying equipment, thus reducing the investment required for machinery, machinery space and buildings and also materially reducing maintenance expense. The majority of the steam traps and about threefourths of the drier steam joints and siphons required in connection with ordinary drying equipment can be eliminated by the use of the present invention. The paper can be made stronger and of better quality and in greater varieties than by ordinary methods. By controlling the humidity of the paper for calendering, the paper will ar-.
rive at the calenders at a more constant condition and will calender with a more uniform finish.
By using heat'over and over again in the drying apparatus a substantial economy is effected. Due to the heat recovery system, a saving -in the power required to produce suction in the suction driers is effected by reason of the condensation of the vapor in the discharged air. The recovery of pure hot water for use over again as white water is highly advantageous, avoiding low temperature which tends to congeal the sizing in the paper when made on a Fourdrinier having ordinary press and drier equipment. As there is no escape of'hot vapor into the machine room, the working conditions are much improved for the machine crew. The same condition prevents the condensation of moisture on the ceiling, overhead pipes and the like, and the dripping of dew on the finished paper, thereby preventing damage.
Whatl claim as my invention, and desire to secure by Letters Patert, is:
1. A paper making machine comprising a wet section on which the paper sheet is made in the wet state, drying equipment to which the wet sheet is delivered from said wet section, said drying equipment comprising a series of drying rolls around which the sheet is carried, certain of said rolls being perforated suction drying rolls having associated means for continuously forcing heated air through substantially the entire area of the sheet entrained on said perforated rolls and the other rolls being heated drying rolls, a press throughv which the sheet passes after deliveryfrom said drying equipment, and further terior of the shell will not be serious, and all drying equipment through which the sheet passes after pressing.
2. In paper drying apparatus, a series of driers comprising ordinary driers and suction driers, a housing containing the same, said housing having awarm air inlet, steam coils in said housing for heating the air therein, said coils being arranged in proximity to the suction driers, and coacting felts'for carrying the paper sheet successivelyaround said driers.
3. The improvement in the process of making paper in a continuous sheet which comprises partially drying the sheet before any pressing by drying action involving the carrying of the wet sheet between heated felts and successively forcing large volumes of heated air through the sheet, and thereafter drying the sheet by heating it and successively forcing large volumes of heated air therethrough.
4. The improvement in the process of making paper in a continuous sheet which comprises partially drying the sheet before any pressing by drying action which involves carrying the sheet between heated felts while successively forcing large volumes of heated air therethrough, further drying the sheet before any pressing by heating it and successively forcing large volumes of heated air therethrough, and thereafter drying the sheet by heating it and successively forcing large volumes of heated air therethrough.
5. The improvement in the process of making paper in a continuous sheet which comprises partially drying the sheet before any pressing by carrying the sheet between heated felts while alternately heating and forcing large volumes of heated air through the felts and interposed paper sheet, further drying the sheet before any pressing by alternately heating the sheet and forcing large volumes of heated air therethrough, and thereafter drying the sheet by drying actioninvolving successively forcing large volumes of heated air through the sheet.
6. The improved method of drying paper in the course of manufacture in a continuous sheet which comprises carrying the wet sheet between heated felts while successively forcing large volumes of heated air through the sheet, and further drying the sheet by alternately heating it and forcing large volumes of heated air therethrough and then by successively forcing large volumes of heated air therethrough.
'7. The improved method of drying paper in the course of manufacture in a continuous sheet which comprises carrying the wet sheet between heated felts while alternately heating and forcing large volumes of heated air through the felts and interposed sheet, continuing the drying by heating the sheet and successively forcing large volumes of heated air therethrough, and completing the drying by successively forcing large volumes of heated air through the sheet.
8. A paper making machine comprising awet section on which the paper sheet is made in the wet state, a press remote from the wet section, drying equipment through which the sheet is passed between said wet section and press, said drying equipment comprising a series of suction drying rolls and heated drying rolls in alternation with suction drying rolls, around which rolls successively the sheet is carried, and drying equipment beyond said press comprising a series of suction drying rolls and heated drying rolls in alternation with suction drying rolls, around p 2,091,805 arranged to receive the wet sheet, said drying section comprising a series of alternately arranged suction drying rolls and heated drying rolls and coacting endless aprons of porous material between which the sheet is carried successively around said driers, a second drying section comprising a series of alternately arranged suction drying rolls and heated drying rolls around which the sheet is successively carried 10 and an endless apron of porous material which passes with the sheet successively around said rolls of said second section, said apron being outside the sheet on heated drying rollsand inside the sheet on suction drying rolls, and a third drying section comprising a series of driers ineluding heated drying rolls and suction drying rolls around which successively the sheet is carried.
HARRY A. CHUSE.