WO1999041450A1

WO1999041450A1 - Steam box

Info

Publication number: WO1999041450A1
Application number: PCT/FI1999/000104
Authority: WO
Inventors: Seppo Tavi
Original assignee: Valmet Corporation
Priority date: 1998-02-13
Filing date: 1999-02-11
Publication date: 1999-08-19
Also published as: FIU980081U0; FI3463U1; AU2426299A

Abstract

The invention relates to a steam box (10) for a paper/board machine, comprising a distribution chamber (11), into which steam is passed first, and which steam box comprises steam feed sections (A1, A2, A3 ...), into which the steam can be passed selectively while regulated by valves (12a1, 12a2 ...). The valves (12a1, 12a2 ...) are disposed in a valve cassette (14) which can be moved into the interior of the steam box (10) and out of the steam box for servicing.

Description

Steam box

The invention relates to a steam box in a paper/board machine for passing steam into connection with a paper/board web.

From prior art a steam box is known which is used in connection with a press of the Sym-Press II type and through which hot steam is passed into connection with a paper web in order to reduce the viscosity of water present in the web and to thereby promote removal of water from the web.

The applicant's earlier FI 945969 patent application discloses a steam box structure which comprises a blower part and a separate steam distributor frame and a connecting duct therebetween. The apparatus comprises separate valves through which steam can be passed from the distributor frame through the valves into hoses and further into a distribution chamber/chambers of the blower part and further into connection with a steam distribution surface/a board web/a paper web. Thus, the regulation valves for regulating the flow of steam into the distributor part are situated in a different unit from that of the discharge surface of steam. The regulation valves can thus be placed more readily in a location where it is easy to service them.

Further, prior art arrangements are known in which regulation valves are situated in connection with the blower part itself. In that case, it is possible to service the regulation valves only during shutdown periods.

This application discloses a totally novel type of arrangement for a steam box structure. The invention proposes using a separate cassette which contains steam regulation valves and which can be removed from inside the steam box on support of guides. The cassette can be removed to a service position or moved altogether out of connection of a machine for servicing. The steam box in accordance with the invention is characterized by what is set forth in the claims.

In the following, the invention will be described with reference to some advantage- ous embodiments of the invention shown in the figures of the accompanying drawings, to which embodiments the invention is, however, not intended to be exclusively confined.

Figure 1 A is an axonometric view of a steam box from the front.

Figure IB is an axonometric view of the steam box and from the rear. Dashed lines illustrate a valve cassette and steam feed compartments which are situated inside the steam box and through which steam can be fed from a profiled web width into connection with the web.

Figure 2 shows a section I— I of the steam box illustrated in Fig. 1A.

Figure 3 is an axonometric view of taking the valve cassette out of the interior of the steam box.

Figure 4 shows a section II— II of Fig. IB, i.e. the valve cassette and the steam box in a running position.

Fig. 1A shows a steam box 10 in connection with a paper/board web. As shown in the figure, the flow of steam into connection with the paper /board web can be regulated by regulating the supply of steam into different feed sections A₁,A₂... (different feed sections of the steam box) by means of valves arranged across the width of the steam box. Further, the steam box may comprise a structure by means of which steam is passed into a constant steam feed section A₁₀₀ at the inlet side 50' of a steam discharge surface 50 of the steam box (viewed in the direction of run of the web). At the outlet side 50" of the steam discharge surface 50, there are situated feed sections A^A^A ..., of which there are a plurality across the width of the steam box.

Fig. IB shows the steam box from the rear. As shown in the figure, the steam feed sections A_j,A₂... are arranged across the width of the steam box, and steam can be passed from an inlet chamber 11 through the valves 12a_{1 ;} 12a₂... of a valve cassette 14 into each section A₁,A₂,A₃..., as desired. The figures show an embodiment in which the steam box is disposed in connection with a cylinder surface, in which connection the discharge surface for the steams of the box is curved. The invention is also suitable for straight steam boxes. Thus, in the invention, the shape of the steam box is not restricted in any way.

Fig. 2 shows a section I— I of Fig. 1A. As shown in the figure, steam is passed through an inlet tube into the distribution chamber 11 of the steam box 10 and therefrom, for example, through the valve 12a_j into the steam feed section Ai . The supply of steam into the feed section A_j and further the disch-arge of steam through a discharge surface A{ of the feed section A_t into connection with a paper/board web are regulated by moving a spindle of the valve 12S ^ . Openings O_{l 5}O₂ of a spindle tube 13aι of each valve 12a_{1 ;} 12a₂... open into the space 11, in which connection steam enters a spindle cavity E of the valve 12a₁,12a₂... through the openings O_{l 5}O₂ and further, depending on the position of the spindle 12b of the valve 12a_j,12a₂..., steam is passed, while it is regulated, into an end space 13b of the spindle tube 13a and further from the end space 13b, for example, into the steam feed section A_j situated in connection with the valve 12a_j. The valves 12aι ,12a₂... are situated in the movable valve cassette 14. The valves 12a_1;12a₂... are attached to the cassette 14, which is a box-shaped elongated frame part, the spindle 12b of the valve lla^ extending through a frame surface Ma_j of said frame part. The position of the valve spindle 12b can be adjusted by adjusting the position of the spindle by means of air pressure. The spindle tube 13a is advantageously a flexible, e.g. bellows-like structure, which is positioned at its end 13b, for example, around the steam inlet opening Ji in the wall T_j of the feed section A_j when the cassette 14 is in a running position. The cassette 14, being an elongated box-shaped structure, 4 comprises tube connections e₁₍e₂ inside it for each valve 12a_{1 ;}12a₂... for adjusting the position of each of them by means of air pressure. The air pressure can be passed into a space N on the other side of a piston 12c of the spindle 12b of the valve 12a _j , 12₂.... By means of the compressed air, the spindle 12b can be pressed against the spring force of a spring 13c to a desired regulation position. The cassette 14 preferably comprises wheels, guides or equivalent 15a_} , 15a₂... , on whose support the cassette 14 can be brought from a running position to a servicing position. As shown in the figure, on a bottom part Gi of the space 11 there may be an actuator 16, preferably, for instance, an elongated loading hose, for pressing the end of the spindle tube 12b into contact with the wall T, of the feed section A_l when the cassette 14 is in the running position.

As shown in Fig. 3, the cassette 14 is guided by means of a pull-out casing 17, which defines a steam inlet chamber D_j inside it. The pull-out casing 17 extends sideways perpendicularly to the machine direction of a paper/board machine and, by means of the pull-out tube 17, the cassette 14 can be drawn sufficiently out of connection of the steam box structures to allow servicing operations. As shown in Fig. 3, the cassette 14 has been drawn to a servicing position from inside the pull- out tube 17.

Fig. 4 shows a section II— II of Fig. 1. Connecting hoses fι ,f₂... are connected to the ends of the tubes e₁,e₂ at the end of the cassette 17. On the box structure 14 there may be, for instance, quick-release couplings for connecting the hoses for passing an air pressure from the hoses through the couplings into the tubes which are situated inside the cassette 14 and through which air is passed further to each valve 12a_{l t}12₂....

Claims

1. A steam box (10) for a paper/board machine, comprising a distribution chamber (11), into which steam is passed first, and which steam box comprises steam feed sections (A^A^A ...), into which the steam can be passed selectively while regulated by valves (12a╬╣ ,12a₂...), characterized in that the valves (12a₁,12a₂...) are disposed in a valve cassette (14) which can be moved into the interior of the steam box (10) and out of the steam box for servicing.

2. A steam box as claimed in claim 1, characterized in that the valve cassette (14) can be moved out of the interior of the steam box (10) from its steam chamber space (11) by means of wheels/guides or equivalent (15a_{1 ;} 15a₂...) forming a bearing-like surface therebetween.

3. A steam box as claimed in any one of the preceding claims, characterized in that the valve (12a_1;12a₂...) comprises a spindle (12b) whose position can be adjusted by adjusting the position of the spindle by means of an air pressure, and that the spindle (12b) is arranged to project at one end thereof from a frame box of the valve cassette (14), and that a spring (13c) and a piston (12c) associated with the valve (12a_j , 12a₂...) are disposed in a protected space inside the box structure of the valve cassette (14), and that the end of the valve spindle (12b) extending out of the interior of the valve cassette is disposed inside a spindle tube (13a), and that the spindle tube (13a) can be placed around a steam inlet opening (J_j) of a wall (T_j) of the feed section (A_j,A₂...) when the cassette (14) is in a running position, the spindle tube (13a) comprising at its side surfaces openings (O╬╣ ,O₂) through which steam can be passed into the spindle tube and further out of the end of the spindle tube through the steam inlet opening (J_j) into the feed section (Ai) depending on the adjustment position of the spindle (12b) while the end of the spindle (12b) can be positioned against / in relation to a back-up opening (O₃) situated at the end of the spindle tube (13a) in order to regulate the supply of steam from the chamber space (11) into the interior of the spindle tube and further from the spindle tube into the steam feed section (A_{1 ;}A₂...). 6

4. A steam box as claimed in any one of the preceding claims, characterized in that between the valve cassette (14) and the bottom part of the steam box (10) there is an actuator (16), preferably an elongated loading hose, by whose means the end of the spindle tube (12b') can be pressed against the wall of its feed section (A_j, A₂...) around the steam inlet opening (J_j), whereby the spindle tube (13a) is sealed with respect to its back-up surface (T_j).