US1180752A - Method of drying paper. - Google Patents

Description

J. 0. WOODSOME. METHOD OF DRYING PAPER.

APPLICATION FILED OCT. 20, 19I3.

Patented Apr. 25, 1916.

UIWINE.

JOHN WQOIDSOIVIE, OF CHICAGO, ILLINOIS, ASSIGNOR T CRANE COMPANY, OF

CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS. I

Specification of Letters Patent.

Patented Apr. 25, 1916.

Original application filed. August 19, 1911, Serial No. 645,008. Divided and this application filed October 20, 1913. Serial No. 796,164.

To all whom it may concern:

Be it known that I, JOHN O. WOODSOME, a citizen of the United States, and residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Method of Drying Paper, of which the following is a full, clear, and exact description.

This invention relates generally to the art of paper making, and more particularly to an improved manner of drying paper in paper drying machines of the heated cylinder type, and it is a division of my co-pending application, Serial No. 645,008, filed August 19, 1911. v

In this art, it is well known to pass the wet paper web over a series of heated drying rolls, which are usually arranged in two or more rows, the members of one row being disposed in-an alternate arrangement with respect to the members of an adjacent row, so that the paper web passes diagonally over and between the rolls. When the web enters the feed end of the machine for passing over the initial rolls, it is naturally in the wettest stage in so far as the drying operation is concerned. At this stage it frequently contains 50% moisture and as the web progresses rearwardly over the rolls it correspondingly parts with its moisture,

- emerging at the rear end in a dry state.

In some of the types of machinesheretofore used, itwas customary to subject the wet web to steam at a stated. temperature, and in the event of any change required to be made in the temperature of the steam in the rolls, an attempt would be made to obtain this change by regulating the pressures at which the live steam entered the machine.

would regulate the steam pressure in anendeavor to obtain the proper temperature to evenly dry out the web as it passed over the rolls.

ThlS' generally has been found unsatisfactory. Inattention on the partof the oporator frequently caused a breakage of the web, and a consequent delay to the drying operation from uneven. drying, finally resulting in the production of an inferior grade of paper. Furthermore, if the temperature at the Wet end, that is in the initial cylinders, be too high, the pulpy web would be blown away from the cylinders, or would crack and blister.

Another disadvantage prevalent in machines of this character, was the accumulation of water of condensation and air in the rolls, which condition to a large extent detracted from the radiating efficiency of the rolls, and seriously impaired the capacity of the drying apparatus as a whole.

The purpose of this invention is to overcome these defects, and to provide a simple and effective method of drying paper, or the like, requiring but little or no attention from operators; and a method which in effect provides means for automatically regulating and controlling the amount of work to be done, which, in other words, is the automatic application of heat in correct ratios throughout the apparatus, in order to obtain an even drying out of the web, and to avoid breakage and consequent delay to the drying operation. a

One of the primary objects of my invention is the provision of a method which provides for the free circulation of steam through the cylinders to obtain their maximum drying capacity, in contradistinction to the bottling up of the steam in rolls, which is the prevailing situation owing to an attempt to utilize the latent heat throughout the system, which, to a large extent was defeated by the accumulation of condensation and air in the rolls. Another object of the invention resides in the provision of a novel method for supplying large quantities of heat at relatively lower temperatures to the Wet end of the machine, the point where the largest quantities of heat units are-fabsorbed.

In carrying out my invention, the wet web of paper, after leaving the squeezing rolls, is intended to be passed over and between heating rolls or cylinders of a paper drying machine, which may be of the type illustrated in the accompanying drawing, and more specifically set forth in the aforesaid co-pending application for Letters Patent.

It is considered preferable to divide. the series of heating rolls 1, into a plurality of drying sections, such as for example the sections A, B, C, and D; though it will be under- I stood that the method hereinafter describedis applicable to any preferred assemblage of heating rolls, and in any desired number of sections. Steam is supplied to the rolls 1 in sections B, C and D, in any suitable manner, such as through the media of their respective headers2 .and pipe connections 3; the outlet from the rolls being through the pipes 1 4 which communicate with the return headers 5. These in turn are connected to the supply header 2 of section A through the pipes 6 and 7. The rolls then in section A, which represents the wet end, are

adapted to receive their supply of steam from the rear section, or sections, as the case may be.

Prior to imparting rotary movement to the, rolls 1, I cut in the supply of steam for the rolls in sections B, O, and D,hereinafter termed the rear sections,so that the steam through the rear sections enters the rolls in section A, and in its passage forces out the air "in all the .rolls, and thoroughly heats the latter in readiness to receive the paper web. The rolls are" then revolved, as

is usual, and the wet web enters the section A and initially passes over the rolls 1 comprised within this section. The web as thus initially presented contains a large amount of water, frequently as much as 75per cent, and condensing the steam in section A, consequently exerts a pull upon the steam in the rear sections in order to keep the condensing section fully supplied. Bythis means I induce a rapid flow and a free circulation'of steam to obtain the highest efficiency in the application of heat units to'the web as it passes over the 40 rolls. For example, with the steam pressure at five pounds, the steam enters the rear section's at a temperature of above 212, and as the web passes over the rolls in these sections it absorbs the heat from the rapidly '45 flowing steam. As already stated the steam is then induced to enter the condensing section A, where it enters at a temperature of substantially 212, and here the latent heat contained in th stea is utilized for-drying the web at its ettest stage. It follows that the front section A in ieceiving the web at its wettest stage should,

and in this case does at a relatively low temperature, do the greater part of the work,

56 and I find that the web absorbs the latent -heat in this section as fast as itcan draw the steam from the rear sections; where it has been deprived of some of its heat. As previously indicated this more or less rapid to transmission of the steam in the rear'sections, efi'ectual ly prevents the accumulation of condensation and air in the rolls addin considerably to the efiiciency of the drying operation. One of the peculiar advantages of this method of drying out the paper web, re-

sides in the manner in which it adapts itself be thin and of course containing less moisture, it is clear that the rear sections accommodate themselves accordingly to the lesser Work performed in the condensing section A.

In practice it has been found that the method is practically automatic in its operation; that it requires but little attention from operators; that it has positively increased the drying out capacity of the rolls;

that it has eliminated uneven drying of the' Web and consequent breakage of the same; and that it prevents the accumulation of Water and air in the rolls.

I do not desire to convey any impression that my novel method as herein set forth is restricted to any particular grouping of rolls in sections, as it is obvious that the rear sections may be consolidated to form one section embodying a greater 1% lesser number of rolls accordingly as it may be desired. The drawing illustrates my preferred grouping and in the practical carrying forward of my invention I have grouped the rolls in such a manner that the ratio of the area of drying surface in the condensing system to that of the balance of the rolls is preferably about one to four or five, roughly speaking.

Other advantages will readily present themselves to those skilled the art.

illustrated its use what I claim as new and desire to secure by Letters Patent, is the following f 1. In the herein described-method'of increasing the drying action of paper stock drying machines of the grouped heated roll type, which methodconsists in supplying Having thus described my invention and steam at a temperature of above 212 to a group at substantially equalized pressures throughout the rolls of the group, passing the stock-through the group whereby it is subjected'to the drying action of the said steam therein, and simultaneously rapidly abstracting by suction the used steam from the group before appreciable condensation 3 occurs in any of thejrolls of the group, and

m a manner whereby to maintain a rapid g flow-of high temperature steam through the group for the absorption of units of the steam 'by'the passage through the group.

giy sensible heat ock during its 1,1eo,7ta I lit 2. The herein described method of increasing the drying action of paper stock drying machines of the grouped heated roll type, .whieh method consists 'in supplying high temperature steam to a group at substantially equalized pressures throughout the rolls of the group, passing the stock through the group whereby it is subjected to the drying action of the said steam therein, simultaneously rapidly abstracting by suction the used steam from said rolls before appreciable condensation occurs in the group thereby maintaining a rapid flow of the stock.

In testimony whereof l have hereunto 20 signed my name ln-the presence of the two subscribed Witnesses.

JOHN O. WOODSOME.

Witnesses: i W. HERBERT FOWKES,

U. H. GROENLUND.

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