US1704436A - Steam-heating system for paper mills - Google Patents

Description

March 5, 1929. l. c. JENNINGS STEAM HEATING SYSTEM FOR PAPER MILLS March 5, 1929. l. c. JENNINGS STEAM HEATING SYSTEM FOR PAPER MILLS 4 Sheets-Sheet 2 Filed Aug. 19, 1924 f@ ZP da v, waff @nM-y azz-...yf

NWN mwN NNI March 5, 1929. Q JENNINGS STEAM HEATING SYSTEM FOR PAPER MILLS Filed Aug. 19, 1924 4 Sheets-Sheet March 5, 1929.

I. C. JENNlNGS STEAM HEATING SYSTEM FOR PAPER. MILLS Filed Aug. 19, 1924 4 Sheets-Sheet 4 sof Patented Mar. 5, 1929.

PATENT OFFICE.

IRVING- C. J' ENNIN GS, OF SOUTH NORWALK, CONNECTICUT.

STEAM-HEATING SYSTEM FOR PAPER MILLS. i

Application led August 19,

Tue object of this invention is to provide a new and improved steam heating system for driers for paper mills or other machines designed to obtain a rapid circulation of steam therethrough and the removal of all air and condensate therefrom. The drier, which is attached to cfr-used in conjunction with a paper mill or paper making machine, consists of a number of cylinders, around which the wet freshly formed paper is drawn, steam beingl admitted to the inside of these cylinders, whereby they are heated so that the paper will be dried and finished in its passage around the cylinders.V As a large number of cylinders is usually employed, it has been a diificult matter to get steam to i circulate properly through and to get the air and water out of these cylinders. Various syst-ems have been used, but none of them, so far as I am advised, has been entirely satisfactory. y

One method in common use has been to lemploy an individual trap on the exit pipe of each cylinder. ,Th-is has been found to be eficient only where a low steam pressure is used and it is open to the serious objection that a great number. of traps have to be in-` stalled which require more or less attention and which add a great deal to the expense.

Efforts have been made to overcome this difculty by using one trap in connection with several cylinders. This has not proved satisfactory because steam may be blown through one or two of the cylinders irst and the same may back up in the return and prevent the other cylinders from discharging their condensate. i

Another trouble with most systems installed has been due to the fact that they are laid out for one steam pressure and if this pressure varies the cylinders may vbecome j l water bound.

The object of this invention is to overcome' these diilic'ulties, to provide for a more `economic-al use of steam, and to produce better paper.- l y Briefly stated, my improved system is arranged as follows :-The cylinders are dif vided into groups, and steam is supplied at whatever pressure may be desired to one` .group of cylinders. The exhaust from theseV cylinders passes into an exhaust line which is used as the supplyline for the next group Y of cylinders. The groups and piping are so 1924. Serial No. 733,004.

proportioned that not enough steam will pass into the exhaust line to supply the second group of cylinders. An automatic pressure reducing valve is arranged between the steam supply line and the exhaust line of the irst group of cylinders which supplies the second group. This reducing valve is set to maintain a proper differential pressure, whereby the setting of this reducing valve will determine the pressure and tem perature of the steam supplied to the second group of cylinders. Thus a definite differential pressure will always be maintained between. the first group and the second group of cylinders, which assures that the condensate will always be removed properly from the first group. Aysteam trap is applied on the exhaust line from the first group of cylinders to remove any condensate which has accumulated and a thermostatically controlled air valve is provided to allow any air which may accumulate in this part of the system to blow out. The condensate may be withdrawn by a suitable exhausting pumping apparatus or unit. My improved system may bey applied to different groupings of cylinders as hereinafter described.

f This system does away with about twothirds of the traps, and assures a better circulation and a better control of the steam. It has been found in drying paper that it is advantageous to have the temperature at the wet end less than the temperature in the intermediate cylinders. It has also been found advisable to reducethe temperature on the dry end Y The system which I have invented makes possible a graduation of temperature at yeither end of the machine or at the center,

as desired. n

My improved system is illustrated in the accompanying foursheets of drawings, in which Fig. l is a diagrammatic view of a drier with my system applied thereto illustrating one grouping of the employed;

Fig. 2 isa similar view showing another grouping of the cylinders with my invention applied thereto;

Fig. 3 is a detail of one ofthe drier cylinders showing the wa the steam is led into and exhausted there rom; 4

Fig. 4 is an elevation partly in section cylinders which may be having thirty-four till Fig. 9 is a view similar to Fig. 6 showing' a different method of piping employed at higher pressures.

Referring first tol lFig. 1 and in detail, it will be seen that ll have shown in this iigure a paper drier consisting of a number of rotating hollow cylinders C. Steam is admitted through one of the bearings or shafts of each cylinder by a pipe 10. and is exhausted therefrom through a pipe 11 extending through the bearing and having a depending pipe or siphon leg 12, as illustrated in lFig. 3.

ln the system novvunder discussion, the drier cylinders are divided into three groups, an intermediate group and a group at the Wet end and a group at the dry end of the apparatus. ln the drawing, a drier cylinders is illustrated and these cylinders are grouped so that there will be twenty-four in the intermediate group, five in the group at the Wet end, and five in the group at the dry end of the apparatus. r1`he number of cylinders employed and the number of cylinders in each group will be determined by the size of the apparatus and the kind of paper to be handled and the character of drying desired. The numbers stated Will serve for illustration.

The pipe 14 may be supplied with live steam from pipe 15 orwvith exhaust steam through pipe 16 or both. If exhaust steam is used an oil separator and trap is preferably used if the exhaust steam contains lubricant, and a back pressure relief valve vented to the atmosphere is added in the exhaust line.

A pressure reducing valve R is preferably employed in the pipe 15 so that steam at a governed pressure Will be supplied to the line 13. The pressure reducing valve R employed may be of any ordinary or improved type. f

These parts are arranged so that the ins termediate group of drier cylindersvvill be supplied with steam at a governed pressure, say of five pounds. The exhaust pipes treatise 11 from this intermediate group of cylinders are connected to a discharge line 19 extending substantially the length of the apparatus. rlhe supply pipes 10a of the five drier cylinders at the right hand or Wet end of the apparatus are connected to the exhaust line 19. rlhe exhaust pipes 11@ from these live cylinders are connected to a short discharge line 20. A float trap 'l with a thermostatic air vent V is preferably used in connection With each exhaust pipe 11a.

"lfhis'tra ma be of anv Ordinar or nnproved construct-ion. Une form thereof Which may be used is illustrated in Figs. 6 to 9 which show a valve 21 controlled by an open :float 22.

lthe thermostatic air vent consists of a valve which is operated by a thermostatie element which may consist of a spring coil filled with a volatile liquid Which flashes into vapor, the expansion of which closes the valve When the temperature rises to a predetermined point. rlthe valve thus allows air to escape but closes against steam.

lt will be seen that ll expose this thermostatic element of the air vent to the pressure in the system beyond the air valve or to the pressure on the discharge side of the trap so that it Will not be subjected to steam under pressure of the supply. This will prevent the development of excessive pressure which might tend to distort or break the parts.

llt vwill be seen that these thermostatic valves are all open when the apparatus is cold or out of operation, which permits thev rapid escape of air from all parts of the system and allows the drier to heat up very promptly in starting. After the apparatus is Warm no steam is allowed to escape.

Each of the ve cylinders at the left hand or dry end of the apparatus is also connected to the pipe 19 through a supply pipe 10h and the exhaust pipes 11b from these cylinders are connected to a short discharge line 200. Float traps T `With thermostatie air vents arranged as previously described are used in these exhaust pipes 11b.

Asteam pressure reducing valve R is arranged between the steam supply 14 and the exhaust line 19. This pressure reducing valve maybe onehaving a diaphragm 17 operating a weighted valve 18 as shown in Fig. 4. exposed to the pressure in the supply for thisv group of cylinders and the other side to the pressure in the exhaust from this group of cylinders whereby. a substantially constant difference in pressure is maintained between said supply and exhaust.

This is necessary because as the parts are arranged the exhaust from the intermediate group of cylinders is not enough to supply the groups of cylinders at the Wet and dry @ne side of the diaphragm is llt) lli

ends of the machine and this reducing valve exhaust line 19 is slightly gradeddownL wardly from its center to its right and left ends and the final discharge line 23 is slightly graded downward from its ends to a pipe E24 which connects the system to an exhaust unit which preferably is the drier exhaust unit shown in my patent reissued June 26, 1923,"No- 15,637, wet vacuum pumping apparatus. A single unit` preferably only is employed. This unit has an air or gas exhaust pump 25 and a centrifugal liquid pump 26 as illustrated in Fig. 6. These pumps are arranged to withdraw the con densate from the line 23 and to remove the air or gas therefrom and preferably to return the water to the hot well. f

Float traps T with thermostatic air vents which may be similar in construction to the trap T previously described are preferably arranged between the line 19 and the discharge pipes extending from the short lines 20 and 200. The function of the traps and vents as arranged in all the locations described is to allow any liquid condensate to pass along and not bloclrtlie supply of steam and to let any an' which may accumulate 1n the system blow along.

By the system described it will be seen that the drier cylinders are always full of steam and free from air and condensate. It will be seen that a minimum of float traps is employed. It will be seen that there will be a rapid elimination of air and condensate in starting the machine and that a minimum amount of steam will be used as there is no waste of steam orhot water. It will be seen that constant temperature conditions will be maintained in the drier cylinders which will vbe highest in the middle and graduated olf to a lower temperature at the wetland dry ends of the apparatus regardless of the speed of the machine or the kind of paper. This arrangement will allow the paperk to be dried at a low temperature and will produce a superior quality of paper.

. My improved system may be applied in many other ways to paper driers. F or example'. the grouping of the cylinders may be such that the pressure of steam may be reduced from the dry end to the wet end of the machine. Such an arrangement is shown in F ig. 2. In this system the cylinders are divided into three groups, Itwelve at the dry end of the machine, twelve at the intermediate, and ten at the wet end of the machine.

`In this system the steam supply line 13 is pipes 11 from these cylinders are connected to the exhaust line 19, to which the pipe 10 of the intermediate group of cylinders are connected. A steam pressure reducing valve R is arranged between the lines 13 and 19, as previously described. The exhaust pipes 11 from the intermediate group of cylinders connect to axsecond exhaust line 190, the supply pipes 10 of the right hand group of cylinders being connected to this line 19() and the exhaust pipes 11 therefrom being connected to a discharge line 23() connected to the exhaust unit. A steam pressure reducing valve R2 is arranged between the main steam line 13 and the exhaust line 190. Float traps T with atmospheric relief vents are arranged between the lines 19 and 190 and between the lines 190 and 230.

With this system traps need only be employed in the exhaust pipes of the right hand group of drier cylinders near the wet end of the machine. y `In this system the exhaust from the cylinders at the dry end of the machine is not sufficient to supply the line 19, the reducing valve R"admitting steam thereto for this purpose, andthe exhaust in the line 190 is not sufficient to supply the group of cylinders at the wet end of the machine, steam being admitted thereto to make up the supply by the reducing valve R2.

These reducing valves may be arranged so that for illustration fifteen pounds of steam pressure may be applied to the .left hand group of cylinders, seven and one half pounds to the intermediate group, and two pounds to the right hand group. Thus, the steam which comes olf the exhaust from each group of driers is utilized in the next group of driers and on the last group the temperature is so low that the exhaust is practically water.

Thus, whatever steam comes off from the exhaust from the first group of cylinders is employed in the second group of cylinders and whatever steam comes oft' from the exhaust from the second group of cylinders` is employed inthe third group of cylinders and the exhaust from the third group of cylinders will be as at low pressure as possible, as, even if it is under atmospheric pressure, it will be taken lcare of by the cxhaust unit. e

Thus, by the arrai'igcments described steam is most economically employed, the device is not apt to bind or water log and a tine grade of paper can beproduced.

The steam pressures and their relative differences and also the grouping of the cylinders will be varied and designed for different conditions, products or plants. ,1

The arrangement herein shown and described may be greatly varied by a skilled mechanic without departing fromA thescope of my invention as expressed in 'theclaims f-llaving thus fully described my invention, what l claim and desire to Isecure by llietters Patent is z# l l. rfhe combination with drier cylinders, of a steam heating system therefor comprising a line for supplying steam toa group of cylinders, a line for conducting the exhaust therefrom to another group of cylinders at subnormal pressure, and means for con ystant-ly supplying steam to this exhaust line to maintain a substantially fixed pressure or temperature therein.

2. `rll`he combination with drier cylinders,V

of a steam heating system therefor compris` ing a line for supplying steam to a group of cylinders, a line for conducting the exhaust therefrom to another group of cylinders at subnormal pressure, and means for constantly supplying steam to this exhaust line to maintain a substantially fixed difference in pressure between said supply andexhaust lines.

3. 'llhe combination with drier cylinders, of av steam heating system therefor comprising a line for supplying steam to a group of Cylinders, an exhaust line for conducting the exhaust therefrom to another group of cylinders at subnormal pressure, and a pressure reducing Valve between the supply line and the exhaust line to maintain a substantially fixed difference in pressure between said supply and exhaust lines by constantly adi mitting steam to said exhaust line.

It. rfhe combination with drier cylinders, of a steam heating system therefor, a line for supplying steam to a middle group of cylinders, an exhaust line for conducting the exhaust therefrom at subnormal pressure to a group of cylinders at the wet end and to a group of cylinders at the dry end of the machine, and means for constantly supplying steam to this exhaust line to maintain a substantially fixed difference -in pressure between said supply and exhaust lines.

5. rlhe combination with drier cylinders, of a steam heating system therefor comprising a line for supplyingisteam to a group of cylinders, an exhaust line for conducting the exhaust therefrom to another group dersat subnormal pressure, means for constantly supplying steam to this exhaust line to maintain a substantially `fixed difference in pressure between said supply and exhaust lines, and a unit for withdrawing the condensate from the second group of cylinders. 6. rlhe combination with drier cylinders,

. of a steam heating system therefor, comprising a line for supplying steam toa middle group of cylinders, an exhaust line for conducting the exhaust therefrom at subnormal pressure to a group of cylinders at` the wet end and to a group of cylinders at the dry end of the machine, means for contantly supplying steam to this exhaust and to maintam a substantially fixed difference in presifroafiae sure between said supply and exhaust lines, and a unit for withdrawing the condensate from the groups of cylinders at the wet and dry ends of the machine. 7. The combination with drier cylinders, ofl a steam heating system therefor, comprising a line for supplying steam to a group of cylinders, an exhaust line for conducting the exhaust therefrom' to another group of cylinders at subnormal pressure, means for constantiy supplying steam to this exhaust line to maintain a substantially vfixed difference in pressure between said supply and exhaust lines, and a trap between the exhaust line supplying the second group of cylinders and the discharge therefrom.

8. lhe combination with drier cylinders, of a steam heating system therefor, comprisling a line for supplying steam to a middle group of cylinders, an exhaust line for con- S5 ducting the exhaust therefrom at subnormal pressure to a group of cylinders at the wet end and to a group of cylinders at the dry end of the machine, means for constantly supplying steam to this exhaust line to maintain a substantially fixed difference in pressure between said supply and exhaust lines, and traps between the exhaust line supplying the groups of cylinders at the wet and dry ends of the machine and the discharge therefrom. y f

9. rlhe combination with drier cylinders, of a steam heating system therefor, compris` ing a line for supplying steam to a group of cylinders, an exhaust line for conducting the exhaust therefrom to another group of cylinders at subnormal pressure, means for constantly supplying steam to this exhaust line to maintain a substantially fixed difference in pressure between said supply and exhaust lines, a trap between the exhaust line supplying the second group of cylinders and the discharge therefrom, and a unit for withdrawing the condensate from the discharge line of the second group of cylinders.

10. 'lhe combination with drier cylinders, of a steam heating system therefor, com prising a line for supplying steam to a middle group of cylinders, an exhaust line for conducting the exhaust therefrom at sub- H5 normal pressure to a group of cylinders at the wet end and to a group of cylinders at the dry end of the apparatus, means for constantly supplying steam to this exhaust line to maintain a substantially fixed difference in pressure between said supply and exhaust lines, discharge lines from the groups of cylinders at the wet and dry ends of the apparatus, steam traps between the exhaust supply and discharge lines of the groups of cylinders at the wet and dry ends of the apparatus, and a unit for withdrawing the condensate from the discharge lines of the groups of cylinders at the wet and dry ends of the apparatus.

ll. The combination with drier cylinders,

of a steam heating system therefor, comprising a line for supplying steam to a group of cylinders, an exhaust line for conducting the exhaust therefrom to another group of cylinders at subnormal pressure, means for constantly supplying steam to this exhaust line to maintain a substantially fixed difference in pressure between said supply and exhaust lines, and steam traps in the discharge pipes from the second group of cyl-V inders.

12. The combination with drier cylinders, of a steam heating system therefor, comprising a line for supplying steam to a group of cylinders, an exhaust line for conducting the exhaust to another group of cylinders at subnormal pressure, a discharge line therefrom and a thermostatic air Vent between the exhaust and the discharge lines, the thermostatic element thereof being exposed to the discharge, and means for constantly supplying steam from said supply line to said exhaust line.

13. The combination with drier cylinders, of a steam heating system therefor, comprising a line for supplyingsteam to a groupof cylinders, an exhaust line for conducting the exhaust therefrom to another group of cylinders at subnormal pressure, a discharge line therefrom, means for constantly supplying steam to the exhaust line to maintain a substantially fixed difference in presf sure between said supply and exhaust lines,

steam traps between the exhaust line conducting the exhaust to the second group of cylinders and the discharge line therefrom, and thermostatic air vents between the exhaust line and the discharge line having their thermostatic elements` exposed to the discharge.

In testimony whereof I have hereunto affixed my signature.

IRVING C. JENNINGS.

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