Steam and condensate coupling for a drying cylinder in a paper machine

Abstract: The invention concerns a steam and condensate coupling (26) for a drying cylinder (10) in a paper machine. The steam and condensate coupling (26) for a drying cylinder in a paper machine comprises a piston ring (29) and therein a seal (24), which is pressed by means of steam pressure against the revolving axle (10c) or against a flange part (22) or equivalent permanently connected to said axle. In the coupling (26), there is a piston ring (29), which comprises a face (32) that is placed substantially perpendicularly to the axial direction (X) of the roll, or slightly inclined from said perpendicular plane. In the coupling construction, the steam pressure is passed (arrow S) onto said face of the piston ring (29), and a force (F) is produced, by which force the piston ring (29) and the seal (24) provided in same are pressed with force towards the revolving axle (10c). Thereby, by means of the steam pressure, a pressure-tight joint is provided between the stationary, non-revolving seal (24) and the revolving axle (10c).

Description: The invention concerns a paper machine according to the preamble of claim 1, being based on US-A-2,402,224. As further prior art is mentioned GB-A-1 540 516. By means of a steam and condensate coupling for a drying cylinder, a pressure-tight joint is formed between the revolving axle of the drying cylinder and the stationary constructions. By means of spring force and steam pressure, a seal ring is pressed against a revolving flange attached to the end of the axle. Steam and condensate pipes are passed through the axle journal, and a seal ring is fitted to surround said pipe systems. The installation of a prior-art coupling is a time-consuming operation that imposes high requirements. The flanges attached to the end of the axle of the drying cylinder perform a swinging movement axially and radially. Frequently, such swinging remains to be corrected after the installation. The replacement of the carbon seal in the coupling constructions is difficult to carry out. The force with which the carbon is pressed against the flange attached to the end of the axle depends on the spring forces of the springs and of the bellows. Thus, the adjustability of the force is poor and, when the carbon seal is worn, the spring force becomes lower. In the prior-art coupling constructions, in starting situations, a high starting friction is produced on the carbon seal. Thereby the carbon is worn and damaged rapidly. The object of the present invention is to form a steam and condensate coupling of a novel type for a drying cylinder in a paper machine in which coupling the drawbacks mentioned above are avoided. The object of the invention has been achieved by means of a solution of equipment in which the sealing pressure applied to the carbon ring is mostly produced by a steam pressure applied to the face of a piston part. In view of a situation of negative pressure, the construction is provided with spiral springs. As a static seal, between the carbon and the piston part, a flat seal is used, and between the piston part and the coupling body a groove-ring seal. As a limiter of radial movements of the piston, a guide band made of teflon is used. Rotation of the carbon ring is prevented by three pins and by a press ring. The paper machine in accordance with the invention has the features in the characterizing clause of claim 1. The invention will be described in the following with reference to some preferred embodiments of the invention illustrated in the figures in the accompanying drawings, the invention being, yet, not supposed to be confined to said embodiments alone. Figure 1 is a sectional view of a steam and condensate coupling in accordance with the invention for a drying cylinder in a paper machine. What is shown is one end of the drying cylinder in a paper machine. Figure 2 shows the area A in Fig. 1. What is shown is an enlarged view of a coupling in accordance with the invention. Figure 3 shows a second preferred embodiment of a coupling in accordance with the invention. In the interior of the mantle 10a, the drying cylinder 10 comprises a space D, into which the steam is passed. The mantle 10a of the drying cylinder 10 is connected to the axle journal 10c by means of the flange 10b. The drying cylinder 10 is fitted to revolve on bearings 11. The steam is introduced through a system of steam pipes 12 into the space inside the drying cylinder 10, and upon condensation of the steam the condensate water is carried out of the drying cylinder through a system of condensate pipes. The steam is passed out of the inlet steam pipe 12 into the steam pipe 13 parallel to the central axis X of the drying cylinder through perforations 13a at the end of the pipe. The steam flow out of the inlet steam pipe 12 into the steam pipe 13 through the perforations 13a at its end is illustrated by the arrows L 1 . The steam is discharged into the space D in the interior of the mantle 10a of the drying cylinder in the way indicated by the arrow L 2 . After the steam has condensed and delivered its heat to the drying process, the condensate is carried, being collected by the suction pipe 14, out of the condensate groove 15 provided on the inner face of the mantle 10a. The suction pipe is carried by a support 16. When the sense of rotation of the drying cylinder 10 is reversed, the position of the suction pipe 14 can be reversed. The condensate water is carried out of the space D in the way indicated by the arrow L 3 . Out of the suction pipe 14, the condensate is transferred into the condensate pipe 17, which is parallel to the central axis X of the drying cylinder 10. As is shown by the arrow L 4 , the condensate is carried further through the flow indicator 18 into the exhaust pipe 19 and further out of connection with the drying cylinder. The outflow of the condensate is promoted by means of a pump (not shown). The condensate pipe 17 runs inside the steam pipe 13. As is shown in the figure, the outer steam pipe 13 is supported by means of a support bushing 20. A shield pipe 21 is passed from the support bushing to the end flange 22 connected to the axle. The end flange 22 is connected to the end of the axle 10c by means of a screw 23, and the end flange 22 comprises a front face E, with which the seal, preferably a carbon ring 24, is connected. The steam pressure is passed out of the space 25 between the shield pipe 21 and the steam pipe 13, out of the interior of the cylinder, to the condensate and steam coupling 26 in accordance with the invention. Fig. 2 is a more detailed illustration of the area A in Fig. 1 and of the steam and condensate coupling 26 in accordance with the invention. As is shown in Fig. 2, the steam and condensate coupling 26 comprises a support frame 27 and therein an annular space 28 for a piston ring 29. The piston ring 29 is fitted to move in the axial direction (direction X) of the steam and condensate pipe and of the cylinder. The piston ring 29 comprises a piston part 30 and a projection part 31 projecting inwards from the piston part, said projection part 31 comprising a face 32 substantially perpendicular to the axial direction X, said face 32 being fitted to be affected by the steam pressure. The inside wall 33 defined by the annular space 28 in the support 27 comprises a groove 34, to which a seal 35, preferably a seal band, can be fitted. A second seal 37, preferably a groove-ring seal, is fitted to be effective between the wall of the annular space 28 and the piston ring 29. By means of the seal 37, access of the pressure into the space G between the end face of the piston part and the ring groove is excluded. The flange 22 that revolves along with the axle 10c is connected in a sealing way against the seal ring 24 proper when the steam pressure is passed into contact with the face 32 of the piston ring 29. The seal 24, preferably a carbon ring seal, is fitted between the end face of the piston part and the front face E of the flange 22. The seal 24 is fitted to be attached to the piston ring 29 itself by means of a separate fastening ring 38 at the side opposite to the face of effect of the steam pressure on the projection part 31 of the piston ring 29. In such a case, the force F acts directly at the seal 24. Detrimental torque effects do not arise. As is shown in Fig. 2, the seal 24 is attached to the piston ring so that the shoulder f on the fastening ring 38 engages a counter-shoulder g on the seal 24. When the fastening ring 38 is pressed by means of a screw R 1 or spring into contact with the piston part 29, the fastening ring 38 presses the seal 24 into tight contact with the piston part 29. In the way shown in the figure, the other extreme position of the piston part is adjusted by means of a screw R 2 passed through the support 27, which screw is freely engaged in a hole h made into the piston ring 29. A radial movement of the piston part 29 is prevented by means of a seal band 35, which is fitted between the rotatory support and the piston ring 29. Fig. 3 shows a second preferred embodiment of a coupling in accordance with the invention. In this embodiment, the piston ring 29 comprises a spring cavity h, into which the spring 39 is fitted when the spring acts between the bottom i of the spring cavity h and the bottom j of the ring groove provided for the piston part 29 in the rotatory support 27. By means of the force of the spring 39, the seal 24, preferably a carbon ring or any other durable seal, is kept in contact with its counter-face, i.e., in the embodiment shown in the figure, with the end face E of the flange connected to the end of the axle 10c. Also in the embodiment shown in Fig. 2, the sealing force proper is produced by passing the steam pressure out of the space D, in the way indicated by the arrow S, onto the face 32 of the piston ring 29 and by thereby, by means of the force F, acting upon the piston ring 29. By means of the force F, the seal 24, which is attached to the piston part 29, is pressed against the end face E of the flange 22 that revolves along with the cylinder 10. Rotation of the carbon ring or of an equivalent seal 24, such as a ceramic seal, is prevented by between the piston part 29 and the seal 24 employing a pin 40 that prevents rotation.

Claims: Paper machine with a revolving drying cylinder (10) having an axle (10c) supported by a bearing (11) and a stationary coupling construction (26) for supplying steam to the cylinder and for sucking condensate from the cylinder through steam and condensate conduits (13, 17), which extend through the coupling construction (26) and the axle (10c) into the cylinder interior (D), a pressure tight joint being provided between the revolving axle and the coupling construction by means of a seal (24) surrounding the conduits (13, 17) and pressed against the axle (10c) or a flange part (22) thereof or equivalent attached thereto, characterized in that the seal is part of the stationary, non-revolving coupling construction and is axially pressed against a front face (E) of the axle (10c) or flange part (22) thereof or equivalent attached thereto by means of a piston ring (29) to which the seal (24) is connected, the piston ring (29) surrounding the conduits which consist of pipes (13, 17) and being axially movable within the coupling construction (26), that the piston ring (29) is provided on its side opposite the seal (24) with a face (32) substantially perpendicular to the axis (X) of the cylinder (10), and that a space (25) is provided between the interior of the cylinder axle (10c) and the pipes (13, 17), between the seal (24) and the pipes (13, 17) and between the piston ring (29) and the pipes (13, 17) in order to transfer the steam pressure in the cylinder to the face (32) of the piston ring (29) for pressing the piston ring and the seal (24) connected thereto towards the axle (10c). Paper machine as claimed in claim 1, characterized in that the piston ring (29) comprises a piston part (30), which is fitted to move in an annular space (28) in a support (27) provided in the coupling construction (26), and a projection part (31) that projects towards the axis (X) of the cylinder and comprises said face (32). Paper machine as claimed in claim 2, character- ized in that, between the piston ring (29) and the support (27), the coupling construction comprises a first further seal (37), preferably a groove-ring seal, and that on one wall of the annular space (28), the coupling comprises a second further seal (35), preferably a seal band, which is fitted to minimize the radial movement of the piston ring (29). Paper machine as claimed in any of the preceding claims, characterized in that said seal (24) is attached to the piston ring (29). Paper machine as claimed in any of the preceding claims, characterized in that the seal (24) is attached to the piston ring (29) by means of a fastening ring (38). Paper machine as claimed in claim 5, characterized in that the seal (24) comprises a shoulder (g), which is jointly operative with a shoulder (f) on the fastening ring (38), whereby, when pressed into contact with the piston ring (29) by means of a screw (R 1 ) or spring, the fastening ring (38) presses the seal (24) by means of its shoulder (f) into its position in contact with the piston ring (29) while the shoulder (f) on the fastening ring (38) is engaged with the shoulder (g) on the seal (24). Paper machine as claimed in any of the claims 2-6, characterized in that the coupling construction (26) comprises a spring (39) between the piston ring (29) and the support (27), which spring (39) is fitted, by means of its spring force, to press the piston ring (29) and the seal (24) against the revolving axle (10c) or against a flange attached to said axle. Paper machine as claimed in claim 7, characterized in that the spring (39) between the piston ring (29) and the support (27) is fitted in a spring cavity (h) in the piston ring (29), and it is fitted between the bottom (i) and the bottom (j) of the annular space (28) provided for the piston part in the support (27). Paper machine as claimed in any of the claims 2-8, characterized in that the coupling construction (26) comprises a screw (R 2 ) between the support (27) and the piston ring (29), the extreme position of the movement of the piston ring away from the revolving axle (10c) being adjustable by threading of said screw.

Inventors: JAATINEN ERKKI, JUSSILA KALERVO, MOILANEN ESA, VIITANEN OLAVI, JAATINEN, ERKKI, JUSSILA, KALERVO, MOILANEN, ESA, VIITANEN, OLAVI
Applicants: VALMET CORP, VALMET CORPORATION
Application year: 1992
Main classification: D21F5
IPC codes: D21F5