US1575615A - Heating system for paper driers - Google Patents

Description

March 9 1926.

A. E. BROUGHTON HEATING SYSTEM FOR PAPER DRIERS Filed March .15, 1 2 sheetvsheot A l; afforuu Mamh '9 31926.

A. E. EROUGHTQN HEATING SYSTEM FOR PAPER DRIERS Filed March 15 1924 2 Sweats-Sheet 2 Patented Mar. 9, 1926.

ARTHUR E. BROUGHTON, 0F MINNEAPOLIS, MINNESOTA.

HEATING SYSTEM FOR PAPER DRIERS.

Application filed March 15, 1924. I Serial No. 699,464.

To all whom it may concern:

Be it known that I, ARTHUR E. BROUGH- TON, a citizen of the United States, residing at Minneapolis, in the county of Hennepin and State of Minnesota, have invented new and useful Improvements in Heating Systems for Paper Driers, of which the following is a specification.

This invention relates to improvements in steam heating systems for paper driers, and includes novel means for removing condensate, air and other gases from the driers and for returning the condensate to a boiler.

It is my object to effect a saving of steam and at the same time to .make it possible to improve the product and increase the rate of drying by providing apparatus in which the useful or available heat in the steam is utilized entirely in the rolls to which it is initially supplied, while the temperature applied at the wet end of the machine is entirely independent of'the temperature applied at the dry end.

A further object of this invention is to provide novel and unusually simple and efiicient means for removing the condensate from the driers and for returning the same to a boiler. This invention also includes improved apparatus for separating air and other gases from condensate and does away with all power driven .mechanism for removing condensate-from the driers.

'As is well known, paper driers of the modern type supply steam at a relatively high pressure to a section or group of driers near the dry end of the machine and then withdraw at least a portion of the steam so supplied for use at a lower pressure in a section of driers nearer the wet end of the inachine. The steam is passed successively from one section of driers to another until it reaches the wet end, and is then condensed and returned to the boiler or otherwise disposed of. In all of such systems known to applicant, the temperature of the driers at the wet end of the machine is dependent to a certain extent at least upon the tempera ture at the dry end. Further, to prevent searing certain kinds of paper, it is necessary to apply at a low temperature (and correspondingly low pressure) at the wet end of the machine, while it is important in order to carry out the drying as rapidly as possible to apply high temperatures and pressures nearer the dry end of the machine. \Vith this common type of machine it is not possible, without sacrificing a substantial amount of the available heat in the steam, to a the ry end and at. the same time to apply, as is frequently desirable, a very low temperature at the wet end. With the system of the present invention, however, the temperatures at the ends of the machine are entirely independent of each other, the temperatures of each section of driers being regulated by independent adjustment of the pressure. In the present system, steam at the desired pressure is transmitted to each of the several driers, wherein its available heat is all utilized and only the condensate (together with tra ped air) is withdrawn from any of the drlers. Steam is prevented from passin from one drying roll to an other and rom one group of driers to another.

I-Ieretofore, it has been common practice to withdraw the condensate and air from the driers by power driven means, such as a vacuum pump, fluid operated ejector, or by reduced pressure in the'receiving header. No such means are employed in the present invention, the condensate being allowed to flow by gravity toga series of direct return traps. v

The invention will be readily understood from the following description, referring to the accompanying drawings. In the drawings, Figure 1 is a diagram of my improved system applied to .the driers of a paper machine; Fig. 2 is a diagramatic elevation partially in central, vertical section, showing a portion of one of the driers and the apparatus for removing air and condensate from the same; Fig. 3 is a sideelevation, partially in central, vertical section, of a suitable return trap -for my system, and Fig. 4

is a plan view of the piping and valves of said trap.

In the drawings I have used the numeral 1 to indicate-the several driers which. are arranged. in sections or groups and adapted ply the desired high temperature at to be supplied with steam from a series of steam headers 2, 3, 4 and 5. The driers are connected by pipes 6 with the headers which are severally supplied with steam at difiering pressures. A high pressure steam line 7 communicates through a reducing valve 8 of common type with the header 2 at the dry end of the machine, while steam at a lower pressure, preferably from the engine exhaust, is transmitted to the headers 2 and 3 by a pipe 9 having a check valve 10 ada ted to prevent flow from the pipe 7 to t e pipe 9. A branch of the pipe 9 communicates with the header 4 through a pressure reducing valve 11, and said branch also connects with the header 5 which also may be supplied with steam at still lower pressures by a pipe 12 leading to the exhaust of the return traps, as hereinafter described. Valves 13 and 14 are adapted to be manipulated to open the header 5 into either the pipe 9 or pipe 12.

The pipes 6 connecting the several driers with the headers open into hollow trunnions at one end of the drying rolls, as

shown in Fig. 2, so as to supply steam to the interior thereof. To withdraw condensate from each drier, a pipe 15 is rovided which extends axially through t e trunnion 16 and projects within the drier to a position 17 near its lower periphery, whence the condensate is withdrawn. The outer portion of the pipe 15 extends downward and communicates through a check valve 18 with one of the several condensate headers 19 or 20. In order to furnish means for testing whether or not condensate is flowing properly through the pipe 15, a valve 21 is connected to said pipe near the lowest point therein between the check valve 18 and drier.

Each of the headers 19 is adapted to drain into one of a series of receivers 22, from which air is allowed to escape through a water trap 23 and a thermostatic valve 24. Air which collects in the top of the receiver 22 is allowed to pass through a pipe 25 into the water trap 23 and then is carried to the valve 24 through a float actuated valve 26 and a pipe 27. Should the receiver 22 become filled with water, any further supply of water would flow into the trap 23 and cause the valve 26 to close and prevent the escape of water through the air valve 24. Any steam which enters the receiver 22 is prevented from escaping by the action of the thermostatic valve 24. To allow water, which sometimes fills the trap 23, to flow back into the receiver 22, a bypass 28 for air is placed on the tra From each of the receivers 22 water is carried to one of a series of return traps 29 by a pipe 30, a check valve '31 being provided to prevent flow from the trap toward the receiver. The pipe 30, as shown in Figs.

3 and 4, connects with a pipe 32 which opens at 33 into the base of the trap 29. This pipe 32 also communicates with an outlet pipe 34 leading to a header 35 (Fig. 1), a check valve 36 being placed in the pipe 34. The trap 29 is of the tilting, direct return type operating at boiler pressure. High.

pressure steam is supplied through a pipe 37, valve 38 and pipe 39 to the top of the trap proper and steam is exhausted from the trap through the pipe 39, a valve 40, a pipe 41 and a check valve 42. The trap 29 is tiltably supported upon bearings 43 and is normally maintained in substantially horizontal position by a wei ht 44 supported upon a lever 45 having a fu crum 46 and pivotally connected at its end 47 to the pipe 32. A stop 48 is provided for limiting the tilting movement of the trap, while levers 49 and 50 are suitably arranged and connected respectively with the valves 38 and 40 so as to actuate. said valves when the trap is tilted.

Water is allowed to flow from the receiver 22 to the trap 29 through the pipe 30, check valve 31 and pipe '32. As the water rises in the trap-29 to a predetermined level therein, the weight 44.becomes over balanced and the trap tilts in the bearings 43 to the stop 48. During the flow of water into the trap, the valve 40 is maintained in open position by the lever 50 and the valve 38 is closed by the lever 49. However, when the trap is tilted to the stop 48 by'in-flowing water, the left ends of the levers 49 and 50 (as viewed in Fig. 3) are depressed to open the steam valve 38 and close the exhaust valve 40. High pressure steam is thus admitted to the trap through the pipe 39 to force substantially all of the water out of the trap through the pipes 32 and 34 past the check valve 36. When substantially all of the water has been forced out, the weight 44 again returns the trap to horizontal position to thereby close the valve 38 and open the valve 42. Pressure in the trap is thus relieved by allowing the escape of steam through the pipe 41 which communicates with the pipe 12. As soon as the pressure becomes equalized, the water again flows from the receiver 22 and the above described operation is repeated.

The several outlet pipes 34 transmit the condensate to the header 35 which communicates through a check valve 51 with a high pressure receiver 52. The pipe 35 communicates with the bottom of the receiver 52 so as to allow water in the receiver to seal said pipe. High pressure steam is supplied to the surface of the water in the receiver 52 by a pipe 53. A conduit 54 is arranged to carry the condensate from the receiver 52 to suitable boiler pumps or traps, from which backward flow' is prevented by a check valve 55 in the pipe 54. A water seal is maintained on the open ends of the pipes 35 and 54 within the receiver 52 by a float actuated valve 56 positioned in the latter pipe.

' Operation.

With certain kinds of paper, high pressures and correspondingly high temperatures may be applied to the rolls near the dry end of the machine. Where such paper closed, the pressure in said connected header.

is to be dried, a valve 7 sure steam pipe is opened; otherwise, the valve 7 may be closed to admit steam under engine exhaust pressureto the header 2. The valve 11 reduces the pressure in the header 4, and where desirable or necessary, steam under a still lower pressure may be supplied to the wet end header 5 by opening the valve 14 and closing the valve 13. Low pressure steam from the trap exhaust may be supplied to the wet end driers or steam at a somewhat higher pressure may be furnished by closing the valve 14 and opening the valve 13.. Thus, as will be readily understood, steam is supplied to the several sections or groups of drying rolls at independently differing pressures.

Sufficient steam is supplied to each roll in the high presbeing removed from the rolls. As long as there is insuflicient condensate to seal the open ends 17 of the pipes 15, the pressures in said pipes and in the header 19 and receiver 22 remains the same as the pressure in the rolls 1 of the same group. However, when sufiicient condensate collects in one of the rolls 1 so that the end 17 of apipe 15 is drops (the check valve 18 preventing any back flow from the header 19) with the re suit that condensate is forced into the pipe 1.5 by reason of the higher pressure in the roll. As soon as the water has been thus raised to the level of the axis of the roll it will flow past the valve 18 into the header 19 and thence into the receiver 22. Obviously, the pressure in the rolls nearest the wet end of a group will be slightly lower than at the dry end of that group. This results in maintaining a pressurein each of the headers 19 equalto the pressure in the rolls nearest the dry end of the corres onding group and condensate stands above tie check valves 18 in the pipes 15 leading to the other rolls of each group at such a height as to compensate for the difierence in pressure in any particular roll and in the It will now be evident that condensateis withdrawn as'fast as it forms in each roll and is allowed to flow into the headers 19.

Similarly condensate is removed from the rolls 1 at the wet end of the machine but flows from the header 20 directly to the trap 29, instead of passing through an interpipe quickly mediate receiver. might otherwise form pockets in the driers is removed with the condensate and delivered to the receivers 22, whence it is allowed to escape through the trap 23 and thermostatic valve 24. Water and steam is prevented from escaping with the air by reason of the arrangement of the water 'tra 23 and thermostatio valve 24, described a ove.

-The several return traps 29 are arranged at a lower level than the receivers 22 and headers 19 and 20, so that condensate flows freely from the receivers and the header 20 into the traps 29, whence it is discharged under boiler pressure, through the pipes 34 All air and gas which and feeder 35 to the high pressure receiver 52. From said receiver the water is carried. by the pipe 54 to suitable boiler feed pumps or traps and then to the feed water place of disposal such as a feed water heater.

ar type of return traps has been described somewhat in detail, obviously, other types of traps could be used with my invention and I do not wish to limit myself to any specific form of trap. It will also be evident that there are other suitable types of pressure reducing valves or pressure regulators which mightbe used in place of the piston oper- While for the sake of clearness, a particu ated reducing valves 8 and 11 shown diagrammatically in the drawings.

It is to be understood that where the term receiver is used in the following claims that the said term indicates a header or other receptacle'for steam from the driers, whether of cylindrical or other shape.

Having described my invention what I claim as new and desire to protect by Letters Patent is:

1. The combinationwith a machine having a plurality 0? arranged in steam at di drying rolls roups, of means for supplying ering pressures to the rolls of the several groups, and means for withdrawing condensate from said rolls comprising, a header,

with said header, and check valves arranged in said pipes to prevent back pressure in said pipes and to allow fluid to be drawn by ravity from said rolls to said header. 2. The combination with a aper making machine having a plurality of drying rolls, of means for-supp ying steam under ressure to said rolls, and means for with rawin condensate from said rolls comprising, a header, a series of pipes severally communicating atone end with said rolls and at the other end with said header, and check pipes severally communicating at' one end with said rolls and at the other end aper making valves arranged in said pipes to prevent back pressure in said pipes and to allow fluid to pass from said rolls to said header, the pressure in said header being maintained substantially equal to the pressure in said rolls.

3. The combination with a paper making vmachine having a plurality of drying rolls arranged in groups, of means for supplying steam at differing pressures to the rolls of the several groups and means for withdrawing condensate from said rolls comprising separate headers for the several groups, pipes severally communicating at one end with said rolls and at the other end with said headers, and check valves arranged in said pipes to prevent back pressure in said pipes and to allow fluid to be drawn from said rolls to the headers by gravity.

4. The combination with a paper machine having a plurality of drying rolls arranged in groups, of means for supplying steam at differing pressures to the rolls of the several groups, means for withdrawing condensate from each of said rolls, a single receiver, means for transmitting condensate from allof said rolls to said receiver, and means for preventing the flow of steam from one of said groups to another.

5. The combination with a paper machine having a plurality of drying rolls arranged in groups, of means for supplying steam at differing pressures to the rolls of the several groups, the heat of the steam being utilized wholly in the rolls to which it is initially supplied, a single receiver and means for transmitting condensate from all of said rolls to said receiver.

6. The combination with a paper machine having a pluralit-yof drying rolls arranged in groups, of means for supplying steam at differing pressures to the rolls of the several groups, the pressures applied in the groups being independent one of another, means for preventing the flow of steam from one of said groups to another, a receiver for each roup, means for transmitting fluid from sai rolls to said receivers and means mounted on said receiver for allowing the escape of air and gases therefrom and for preventing the escape of steam and condensate therefrom.

7. In a pa ermaking machine having a plurality of rying rolls, means for supplying steam under pressure to said r0 ls, a receiver connected by piping with said rolls whereby the pressure in the receiver is maintained substantially equal to the pressure in the rolls, and means adapted to permit the escape of air and gases from said receiver.

8. In a paper making machine having a plurality of drying rolls, means for supplying steam under ressure to said rolls, a receiver connected y piping with said rolls whereby the pressure in the receiver is maintained substantially equal tothe pressure in the rolls, a thermostatic valve on said re ceiver adapted to permit the escape of air and gases therefrom and a water trap arranged to prevent the escape of condensate through said valve.

9. In a paper making machine havin a plurality of drying rolls, means for supp ying steam under pressure to said rolls, a receiver disposed at a lower lever than said rolls connected by iping therewith 'whereby the pressure in t e receiver is mai tained substantially equal to the pressure 'n the rolls and condensate is allowed to flow by gravity from the rolls to said receiver, means adapted to permit the escape of air and gases from said receiver, means for preventing the escape of steam and condensate from said receiver, a returntrap disposed beneath said receiver for condensate therefrom, said trap being adapted to increase the presssure on condensate therein and an outlet pipe. from which condensate is allowed to flow at increased pressure from said trap.

10. In a paper making machine having a plurality of drying rolls arran ed in groups, means for supplying steam at. ifferingpressures to the rolls of the several groups, a

separate receiver for condensate from each or sa1d groups, piping connecting the rolls with the receivers whereby the pressure in the rece ver of each group is maintained substantlally equal to the pressure in .the rolls of the same grou a high pressure tank adapted to receive t e condensate from all of sa1d receivers, and return traps operating under an equally high pressure, severally connected to the receivers and to said tank and arranged to allow condensate to pass by gravit to said tank.

11. The com ination with a machine having a plurality of drying rolls arranged in groups, of means for supplying steam at Clll'fQX'lIlg pressures to the rolls of the several groups, a separate header for the condensate from each group, pipes severally connecting the rolls with the headers, check valves arranged in said pipes to allow fluid to pass from the rolls to the headers, a receiver arranged beneath each of said headers to receive fluid therefrom, the pressure in said rolls, headers and receivers being equalized to permit flow by gravity from the rolls to the receivers, a high pressure tank adapted to receive the condensate from all of said receivers and return traps and piping adapted to deliver condensate from sa1d receivers to said tank. 7

. 12. The combination with a machine having a plurality of drying rolls arranged in groups, of means for supplying steam at inde endently difl'ering pressures to the rolls of tie several groups, aseparate header for the condensate from each group, pipes severally connecting the rollswith the headers, check valves arranged in said pipes from said receivers, a high pressure tank to allow fluid to pass from the rolls to the adapted to receive the condensate from all of l headers, a receiver arranged beneath each said receivers, and return traps and piping of said headers to receive fluid therefrom, adapted to deliver condensate from said 5 the pressure in said rolls, headers and rereceivers to said tank ceivers being equalized to permit flew by In testimony whereoffI have hereunto gravity from the rolls to the receivers, signed my name to this specification. means adapted to allow the escape of air ARTHUR E. BROUGHTON.

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