FI129176B - An arrangement and a method for removing moisture from a pocket space of a drying section of a paper or board machine - Google Patents
An arrangement and a method for removing moisture from a pocket space of a drying section of a paper or board machine Download PDFInfo
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- FI129176B FI129176B FI20205782A FI20205782A FI129176B FI 129176 B FI129176 B FI 129176B FI 20205782 A FI20205782 A FI 20205782A FI 20205782 A FI20205782 A FI 20205782A FI 129176 B FI129176 B FI 129176B
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- ventilator
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
- D21F5/00—Dryer section of machines for making continuous webs of paper
- D21F5/02—Drying on cylinders
- D21F5/04—Drying on cylinders on two or more drying cylinders
- D21F5/042—Drying on cylinders on two or more drying cylinders in combination with suction or blowing devices
- D21F5/046—Drying on cylinders on two or more drying cylinders in combination with suction or blowing devices using pocket ventilation systems
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Abstract
The invention relates to an arrangement and method for removing moisture from a pocket space (100) of a drying section of a paper or board machine. The method comprises arranging a pocket ventilator (10) between an entry side (5a) of the wire (5) and an exit side (5b) of the wire (5), supplying dry air from an inflow chamber (12) of the pocket ventilator (10) through a supply orifice (120) at the second side (10b) of the pocket ventilator to outside of the pocket ventilator (10) and through the wire (5) into the pocket space (100), and discharging moisture air from the pocket space (100) through the wire (5) and through a first discharge orifice (110) at the second side (10b) of the pocket ventilator (10) to an exhaust chamber (11) of the pocket ventilator (10).
Description
FIELD OF THE INVENTION The present invention relates to an arrangement in connection with a drying section of a paper or board machine and more particularly to an arrangement as defined in the preamble of the independent claim 1.
The present invention further relates to a method for removing moisture from a pocket space of a drying section of a paper or board machine and more particularly to a method as defined in the preamble of the independent claim
10.
BACKGROUND OF THE INVENTION The drying section of the present invention is provided as a twin-wire draw in which the drying cylinders in the drying group have been arranged in at least two rows placed one above the other. The upper row cylinders and the lower row cylinders are arranged as interlocked such that the upper and lower row cylinders are not directly above each other. The twin-wire draw is arranged by providing an upper wire and a lower wire by whose means the paper web is pressed against the heated surfaces of drying cylinders. Turn rolls for the wires, also acting as guide rolls, are placed between the cylinders so as to guide the free running paper web between the rows of cylinders. A pocket space is formed in the area between the free draws of the paper web and the upper wire and its turn roll and the drying cylinder in the lower row. Correspondingly, the next pocket space is formed in the area between the free draws of the paper web and the lower wire and its turn roll and the drying cylinder in the upper row.
N 25 Publication US 2002040535 discloses a ventilator used to ventilate an N offset pocket in the drying section of a papermaking machine, and publication EP 3 0472513 discloses a procedure and device in a cylinder drying section of a paper 0 machine. I A typical drying section of a paper machine is arranged inside a hood. a 30 Because the wet paper web is dried in the drying section and the hood is around 2 the drying section, the conditions inside the hood are humid. The hood can be S closed or open, however a wet paper web and hot cylinders make the conditions in the pocket spaces moist in any case. One problem relating to the pocket spaces is that they have a high moisture level present when the paper web is dried. In prior artarrangements blow boxes are provided in connection with the pocket spaces in order to equalize the pressure conditions in the pocket space and to provide more stable paper web running. The blow boxes also create an under pressure which ventilate the pocket space while maintaining the paper web stable.
BRIEF DESCRIPTION OF THE INVENTION An object of the present invention is to provide an arrangement and a method for removing moisture from the pocket space of the drying section of a paper machine and enable saving thermal energy.
The objects of the invention are achieved by an arrangement and a method for removing moisture from the pocket space of the drying section of a — paper machine which are characterized by what is stated in the independent claims. The preferred embodiments of the invention are disclosed in the dependent claims.
The invention is based on the idea of removing moisture, i.e. humid air and water vapour, directly from the pocket space formed in connection with a twin wire draw of a drying section. The invention is further based on the idea of removing moisture in an unsymmetrical pocket space in which the turn roll of the wire defining the pocket space is arranged in the vicinity of a web. In the vicinity means in this connection that the turn roll and the web are separated only by the wire. Moisture is removed by a pocket ventilator extending in a cross-machine direction and arranged in connection with the pocket space, such that the cross- machine moisture profile of the web is well controlled.
In this application the pocket space is defined by the free draws of the web and the upper wire and its turn roll that guides the upper wire and the drying cylinder in the lower row. On the other hand, the adjacent pocket space in the drying section is defined by the free draws of the web and by the drying cylinder in N the upper row and the lower wire and its turn roll that guides the lower wire.
N In this application the web running or arranged to run the web path is I a paper web or a board web.
© In this application a first cylinder is the first one of the cylinders in the E 30 running direction of the web forming the pocket space from where the moisture is N removed with the pocket ventilator provided in connection with the pocket space.
S In other words, the first cylinder is in the running direction of the web the first of a the cylinders in connection with which the pocket ventilator is arranged. The N second cylinder is the next cylinder in the same row of cylinders as the first cylinder and the third cylinder is the cylinder between the first cylinder and the second cylinder arranged in a different cylinder row than the first cylinder and the second cylinder.
In the arrangement in connection with a drying section of a paper or board machine according to the invention, the drying section comprises a first cylinder, a second cylinder, a third cylinder, a turn roll, a wire arranged to travel from the first cylinder through the turn roll to the second cylinder and a web path from the first cylinder via the turn roll to the third cylinder and through the third cylinder to the second cylinder.
The first cylinder, the second cylinder, the third cylinder and the web path between the cylinders form a pocket space.
The first and second cylinders may be the upper cylinders or the lower cylinders and correspondingly the third cylinder may be the lower cylinder or the upper cylinder, depending on the location of the drying section.
The arrangement comprises a pocket ventilator arranged between an entry side of the wire and an exit side of the wire.
The entry side of the wire is the part of the wire which enters the turn roll and the exit side of the wire is the part of the wire which exits the turn roll.
In other words, the exit side and the entry side are separated by the turn roll.
In still other words, the entry side is the side between the first cylinder and the turn roll, and the exit side is the side between the turn roll and the second cylinder where the wire runs.
In still other words, the entry side of the wire is the part of the wire entering the turn roll in the running direction of the wire.
The pocket ventilator is further arranged next to the turn roll.
In other words, the pocket ventilator is arranged in a space which is defined by the entry side of the wire, the turn roll and the exit side of the wire.
The pocket ventilator has a first side arranged toward the entry side of the wire and a second side arranged toward the exit side of the wire.
In other words, the pocket ventilator has a first side and a second side and when _ the pocket ventilator is arranged in connection with the drying section the first side S of the pocket ventilator is towards the entry side of the wire and the second side of N the pocket ventilator is towards the exit side of the wire.
The pocket ventilator ? comprises an exhaust chamber having a first discharge orifice at the second side of © 30 — the pocket ventilator, which the first discharge orifice is arranged to provide a flow = path from the pocket space to the exhaust chamber for exhausting air from the N pocket space.
The discharge orifice is arranged in the pocket ventilator such that 5 the flow path is formed to guide moisture air from the pocket space through the N exit side of the wire to the first discharge orifice and into the exhaust chamber.
The N 35 first discharge orifice comprises one or more openings at the second side of the pocket ventilator, which the one or more openings extending from an outer surface of the pocket ventilator through the structure of the pocket ventilator into the exhaust chamber.
The pocket ventilator further comprises an inflow chamber having a supply orifice at the second side of the pocket ventilator, which the supply orifice is arranged to provide a flow path from the inflow chamber to the pocket — space for supplying air into the pocket space.
The supply orifice is arranged in the pocket ventilator such that the flow path is formed to guide dry air from the inflow chamber through the supply orifice and through the exit side of the wire to the pocket space.
The supply orifice comprises one or more openings at the second side of the pocket ventilator, which the one or more openings extending from an outer — surface of the pocket ventilator through the structure of the pocket ventilator into the inflow chamber.
Alternatively, or in addition, the supply orifice comprises one or more supply nozzles arranged at the second side of the pocket ventilator and being in a flow communication with the inflow chamber.
The first discharge orifice and the supply orifice are provided to the pocket ventilator at the second side of the pocket ventilator which is toward the exit side of the wire such that air from the pocket space is able to move through the wire to the discharge orifice and correspondingly so that the air from the supply orifice is able to move through the wire to the pocket space.
According to the invention the pocket ventilator further comprises a second discharge orifice arranged at the first side of the pocket ventilator which the second discharge orifice is arranged to provide a flow path from an entry space formed between the wire at the entry side of the wire and the first side of the pocket ventilator to the exhaust chamber.
In other words, the entry space is a space between the wire at the entry side and the first side of the pocket ventilator.
The second discharge orifice comprises one or more openings extending from the first _ side of the pocket ventilator through the structure of the pocket ventilator to the N exhaust chamber.
N According to an embodiment of the invention the exhaust chamber and ? the inflow chamber are formed in the pocket ventilator such that the inflow © 30 chamber is next to the turn roll when the pocket ventilator is arranged between E the entry side of the wire and the exit side of the wire.
In other words, the exhaust N chamber is arranged further away from the turn roll than the inflow chamber in 5 the pocket ventilator when the pocket ventilator is arranged at its operating N position.
N 35 According to the invention the pocket ventilator further comprises a first seal element and a second seal element arranged at the second side of the pocket ventilator on opposite sides of the first discharge orifice such that the first seal element is provided toward the wire at the second cylinder, i.e. toward the wire when the wire is at the second cylinder, and the second seal element is provided toward the wire at a free space, i.e. toward the wire when the wire is ata 5 free space, between the supply orifice and the second cylinder such that an exit space is formed between the wire at the exit side of the wire and the second side of the pocket ventilator and between the first seal element and the second seal element. The first discharge orifice may comprise multiple openings arranged to the second side of the pocket ventilator so the first and second seal elements may — be provided on opposite sides of the first discharge orifice such that the multiple openings are provided between the first and second seal elements.
According to the invention the pocket ventilator further comprises a third seal element and a fourth seal element arranged at the first side of the pocket ventilator on opposite sides of the second discharge orifice such that the third seal —elementis provided toward the wire at the first cylinder, i.e. toward the wire when the wire is at the first cylinder, and the fourth seal element is provided toward the wire ata free space, i.e. when the wire is at the free space, between the first cylinder and the turn roll such that the entry space is formed between the wire at the entry side of the wire and the first side of the pocket ventilator and between the third seal element and the fourth seal element.
According to the invention the inflow chamber comprises an equalizing plate arranged to divide the inflow chamber into an inlet chamber section and a supply chamber section. The equalizing plate has apertures through the equalizing plate for providing a flow path from the inlet chamber section to the supply chamber section. The inlet chamber section comprises an inlet arranged to form a _ flow path from outside of the pocket ventilator to the inflow chamber and the S supply chamber section comprises the supply orifice for providing the flow path N form the inflow chamber to the pocket space. The inlet forming the flow path to the ? inflow chamber is in a flow connection with an air supply device which the air © 30 supply device is arranged to supply dry air in a volumetric flow rate of at least 0,1 = - 0,3 m3/s/m. The air coming to the inlet chamber section is dry and preferably hot N air.
S According to the invention the pocket ventilator is connected to a heat N recovery system for removing moisture from the air coming from the pocket space N 35 such that the exhaust chamber is arranged in a flow connection with the heat recovery system.
According to the invention the heat recovery system is further arranged in a flow connection with the inflow chamber for at least partly recirculating the moisture air, which is removed from the pocket space, as a hot and dry air back to pocket space through the inflow chamber.
According to the invention the exhaust chamber is connected to a suction device for exhausting air from the pocket space through the first discharge orifice to the exhaust chamber and further from the exhaust chamber to an exhaust system. Alternatively, or in addition the inflow chamber is connected to an air supply device for supplying air from the air supply device to the inflow chamber and further through the supply orifice to the pocket space.
In the method for removing moisture from a pocket space of a drying section of a paper or board machine according to the invention, the drying section comprises a first cylinder, a second cylinder, a third cylinder, a turn roll and a wire travelling from the first cylinder through the turn roll to the second cylinder and a — web path from the first cylinder via the turn roll to the third cylinder and through the third cylinder to the second cylinder. The first cylinder, the second cylinder, the third cylinder, the web path between the cylinders, the turn roll and the wire between the turn roll and the second cylinder form a pocket space. The first and second cylinders may be the upper cylinders or the lower cylinders and correspondingly the third cylinder may be the lower cylinder or the upper cylinder, depending on the location of the drying section.
The method comprises steps of arranging a pocket ventilator between an entry side of the wire and an exit side of the wire, the pocket ventilator having a first side arranged toward the entry side of the wire and a second side arranged toward the exit side of the wire, supplying dry air from an inflow chamber of the _ pocket ventilator through a supply orifice at the second side of the pocket O ventilator to outside of the pocket ventilator and through the wire into the pocket LÖ space, and discharging moisture air from the pocket space through the wire and ? through a first discharge orifice at the second side of the pocket ventilator to an © 30 exhaust chamber of the pocket ventilator. The pocket ventilator is according to any = embodiment above described in connection with the arrangement. The method N comprises steps of supplying dry and hot air from the inflow chamber through the 5 supply orifice and through the wire at the exit side of the wire to the pocket space N and discharging moisture air from the pocket space through the wire at the exit N 35 side of the wire through the discharge orifice into the exhaust chamber which the steps of supplying and discharging are performed at the same side of the pocket ventilator.
In other words, the method comprises supplying and discharging air through the wire at the exit side of the wire.
The step of discharging air is removing air from the pocket space which is performed by suction.
According to the invention the method further comprises arranging a first under-pressure zone at an exit space between the second side of the pocket ventilator and the exit side of the wire.
The first under-pressure zone being arranged by arranging a first seal element protruding from the pocket ventilator towards the wire at the second cylinder, by arranging a second seal element protruding from the pocket ventilator at the opposite side of the first discharge orifice than the first seal element towards the wire at a free space between the supply orifice and the second cylinder, and by discharging air through the first discharge orifice at the second side of the pocket ventilator to the exhaust chamber.
In other words, the method comprises a step of providing the first and the second seal element on opposite sides of the first discharge orifice and forming the first — under-pressure zone by providing suction such that air is removed from the pocket space through the wire and through the first discharge orifice to the exhaust chamber.
The first under-pressure zone is formed by providing a space between the wire at the exit side of the wire and the second side of the pocket ventilator and further between the first seal and the second seal protruding from the pocket ventilator at the second side of the pocket ventilator and on opposite sides of the first discharge orifice.
The second seal element protruding from the pocket ventilator at the second side of the pocket ventilator between the first discharge orifice and the supply orifice.
According to the method of the invention the method further comprises a step of supplying dry air from the pocket ventilator to the pocket space at a _ volumetric flow rate of 0,1 - 0,5 m3/s/m, i.e. the flow rate is per width of the pocket O ventilator (i.e. per metre). LÖ According to the method ofthe invention the method further comprises ? a step of supplying dry air from the pocket ventilator to the pocket space at a 0 30 volumetric flow rate of 0,1 — 0,4 m3/s/m. = According to the method of the invention the method further comprises N a step of discharging moisture air from the pocket space and through the pocket 5 ventilator at a volumetric flow rate of 0,1 - 0,5 m3/s/m, i.e. the flow rate is per N width of the pocket ventilator (i.e. per metre). N 35 According to the method of the invention the method further comprises a step of discharging moisture air from the pocket space and through the pocket ventilator at a volumetric flow rate of 0,1 — 0,4 m3/s/m.
According to the method of the invention the method further comprises a step of arranging a second discharge orifice at the first side of the pocket ventilator for providing a flow path outside of the pocket ventilator to the exhaust chamber; and a step of arranging a second under-pressure zone at an entry space between the first side of the pocket ventilator and the entry side of the wire.
The second under-pressure zone is arranged by arranging a third seal element protruding from the pocket ventilator towards the wire at the first cylinder, by arranging a fourth seal element protruding from the pocket ventilator at the — opposite side of the second discharge orifice than the third seal element towards the wire at a free space between the first cylinder and the third cylinder, and by discharging air through the second discharge orifice at the first side of the pocket ventilator to the exhaust chamber.
The first under-pressure zone is a space which is delimited by the second cylinder, the wire at the exit side of the wire, the first and second seal elements and the second side of the pocket ventilator.
The first seal element protruding from the pocket ventilator at the second side of the pocket ventilator is directed towards the second cylinder, and the second seal element protruding from the pocket ventilator at the second side of the pocket ventilator is directed towards — the wire at the exit side of the wire between the turn roll and the second cylinder.
The first under-pressure zone is created by suction, for example by means of a suction device connected to the exhaust chamber such that air is drawn from outside of the pocket ventilator at the second side of the pocket ventilator through the first discharge orifice extending between the exhaust chamber and the first under-pressure zone.
The function of the first under-pressure zone is to effectively _ remove moisture from the pocket space.
S The second under-pressure zone is a space which is delimited by the N first cylinder, the wire at the entry side of the wire, the third and fourth seal ? elements and the first side of the pocket ventilator.
The third seal element © 30 protruding from the pocket ventilator at the first side of the pocket ventilator is = directed towards the first cylinder, and the fourth seal element protruding from N the pocket ventilator at the first side of the pocket ventilator is directed towards 5 the wire at the entry side of the wire between the first cylinder and the turn roll.
N The second under-pressure zone is created by suction, for example by means of a N 35 suction device connected to the exhaust chamber such that air is drawn from outside of the pocket ventilator at the first side of the pocket ventilator through the second discharge orifice extending between the exhaust chamber and the second under-pressure zone. The function of the second under-pressure zone is to stabilize the web running from the first cylinder to the third cylinder.
The method of the invention is most advantageously performed by the arrangement according to the invention.
An advantage of the invention is that the moisture of the pocket space can be effectively removed when both hot and dry air is supplied to the same side of the wire between the turn roll and the second cylinder from which the moist air is removed. The air supply and air removal performed at the second side of the pocket ventilator create a controlled airflow in the pocket space resulting an even moisture profile of the web. The advantage of the invention is that moisture is effectively removed from the pocket space only through one part of the pocket space which is the exit side of the wire running between the turn roll and the second cylinder.
BRIEF DESCRIPTION OF THE DRAWINGS The invention is described in detail by means of specific embodiments with reference to the enclosed drawings, in which Figure 1 shows an arrangement according to the invention; Figure 2 shows an arrangement according to the invention in more detailed; and Figure 3 shows an arrangement according to the invention showing successive pocket spaces.
DETAILED DESCRIPTION OF THE INVENTION Figure 1 shows an arrangement according to the invention in which the N 25 method according to the invention is performed. The arrangement and the method N for removing moisture from a pocket space 100 are provided in connection with a 3 drying section of a paper or a board machine. The drying section comprises a first 0 cylinder 1, a second cylinder, a third cylinder, a turn roll 4, a wire 5 extending from I the first cylinder 1 through the turn roll 4 to the second cylinder and a web path w a 30 provided from the first cylinder 1 via the turn roll 4 to the third cylinder 3 and from 2 the third cylinder to the second cylinder 2. The web path w is provided via the turn S roll 4 such that the web path w passes the turn roll 4 such that the wire 5 is arranged between the turn roll 4 and the web running via the turn roll 4. The pocket space 100 is formed as already described between the web path w, the turn roll 4 and the third cylinder 3 and the free run of the wire 5 between the turn roll
4 and the second cylinder 2. The free run of the wire 5 between the turn roll 4 and the second cylinder 2 is an exit side 5b of the wire 5, i.e. wire 5 exiting the turn roll
4. Whereas, the wire 5 entering the turn roll 4 is an entry 5a of the wire 5 which the entry side 5a of the wire 5 runs together with the web path w until separated atthe turn roll 4.
The pocket ventilator 10 comprises a first side 10a and a second side 10b which the first side 10a is arranged toward the entry side 5a of the wire 5 and the second side 10b is arranged toward the exit side 5b of the wire 5. A third side 10c of the pocket ventilator 10 extending between the first side 10a and the second side 10b is arranged toward the turn roll 4. Although the drying section is presented in figure 1 such that the first and second cylinders 1, 2 are at the upper row and the third cylinder 3 is at the lower row, the set up can be vice versa, such that the third cylinder 3 is at the upper row and the first and second cylinders 1, 2 are atthe lower row, and the arrangement and method of the invention still applies.
The arrows at the second side 10b of the pocket ventilator 10 in figure 1 present the air flows between the pocket ventilator 10 and the pocket space 100. In the method the pocket ventilator 10 is arranged between an entry side 5a of the wire 5 and an exit side 5b of the wire 5 such that the third side 10c of the pocket ventilator 10, i.e. the bottom of the pocket ventilator 10 in this configuration is next — to the turn roll 4. When the configuration is upside down as it is in the adjacent pocket space, then the top of the pocket ventilator 10 is next to the turn roll 4. The dry and hot air is supplied from the pocket ventilator 10 through a supply orifice (shown in figure 2) and through the exit side 5b of the wire 5 to the pocket space 100 which is illustrated with the arrow directed away from the pocket ventilator 10 and the moisture air is discharged, i.e. removed, from the pocket space 100 _ through the exit side 5b of the wire 5 and through a first discharge orifice (shown O in figure 2) to the pocket ventilator 10 which is illustrated with arrows directed LÖ toward the pocket ventilator 10. In the method the ventilation between the pocket ? space 100 and the pocket ventilator 10 is arranged through the second side 10b of © 30 the pocket ventilator 10 and through the exit side 5b of the wire 5. = The figure 2 shows in more detailed the arrangement in connection N with the drying section in which the pocket ventilator 10 is provided between the 5 entry side 5a of the wire 5 and the exit side 5b of the wire 5 and next to the turn N roll 4. The pocket ventilator 10 comprises at the second side 10b of the pocket N 35 ventilator 10 a first seal element 13 protruding from the pocket ventilator 10 toward the second cylinder 2 and a second seal element 14 protruding from the pocket ventilator 10 toward the exit side 5b of the wire 5 at a free space between the turn roll 4 and the second cylinder 2 and in more specifically between a supply orifice 120 and a first discharge orifice 110 of the pocket ventilator 10. The first seal element 13 and the second seal element 14 define an exit space 50b between the second side 10b of the pocket ventilator 10 and the exit side 5b of the wire 5. The moisture air removed from the pocket space 100 to the pocket ventilator 10 is discharged through the exit side 5b of the wire to the exit space 50b in which a first under-pressure zone is created by providing suction through the first discharge orifice 110 from a suction device connected to the exhaust chamber 11 of the pocket ventilator 10. The dry and hot air is supplied to the pocket space 100 from the inflow chamber 12 of pocket ventilator 10 through the supply orifice 120 and through the exit side 5b of the wire 5. An area around the supply orifice 120 outside the pocket ventilator 10 is delimited by the second seal element 15 and a fifth seal element 17 protruding from the third side 10c of the pocket ventilator 10, i.e. from the side of the pocket ventilator 10 next to the turn roll 4. The fifth seal element 17 protruding toward the turn roll 4 such that the supplied air from the supply orifice 120 will not be led to the first side of the pocket ventilator 10, but all the air will be led to the pocket space 100. The inflow chamber 12 is divided into two sections, an inlet chamber section 12a and a supply chamber section 12b which are separated by an equalizing plate 112 having apertures through the equalizing plate for allowing air to pass through the equalizing plate 112. The pocket ventilator 10 further may comprise a third seal element 15 and a fourth seal element 16 protruding from the first side 10a of the pocket ventilator 10 toward the entry side 5a of the wire 5. The third seal element 15 and _ the fourth seal element 16 define an entry space 50a between the first side 10a of O the pocket ventilator 10 and the entry side 5a of the wire 5. The third seal element LÖ 15 and the fourth seal element 16 are also provided on opposite sides of a second ? discharge orifice 111 arranged at the first side 10a of the pocket ventilator 10. The © 30 entry space 50a forms a second under-pressure zone which is created by providing = suction through the second discharge orifice 111 from a suction device connected N to the exhaust chamber 11 of the pocket ventilator 10. 5 The first side 10a of the pocket ventilator 10 is next to the entry side 5a N of the wire 5 coming from the first cylinder 1 with the web path w.
The web path N 35 wand the wire 5 are separated at the turn roll 4 from where the web path continues to the third cylinder 3 and from the third cylinder 3 to the second cylinder 2 at where the wire 5 and the web path w are united. The turn roll 4 is positioned unsymmetrically in relation to the first cylinder 1 and the second cylinder 2 such that the pocket space 100 is larger at the exit side 5b of the wire 5 and therefore the ventilation of the pocket space 100 is provided through the exit side 5b of the wire5.
Figure 3 shows an arrangement according to the invention in which successive pocket spaces 100 and successive pocket ventilators 10 provided to remove moisture from said successive pocket spaces 100 are shown. The figure shows an upper wire and a lower wire, i.e. two wires 5, such that the wire 5 at the upper row is running from the first cylinder 1 to the second cylinder 2 via the turn roll 4, and the wire 5” at the lower row is running from the third cylinder 3, which is for the wire 5’ at the lower row the first cylinder 17, via the turn roll 4 to the fourth cylinder, which is for the wire at the lower row the second cylinder 2. Therefore, the first cylinder 1, 1' in the context of this application means the first — cylinder in connection with which the pocket ventilator 10 is arranged in the running direction of the wire 5 prior to the pocket ventilator 10. Therefore, the first and second cylinders 1, 2, i.e. the cylinders in the upper row of cylinders, are the first and second cylinders for the pocket ventilator 10 provided in connection with the wire 5 at the upper row, i.e. the upper wire, and the third and fourth cylinders in the lower row of the cylinders are the first and second cylinders 1’, 2” for the pocket ventilator 10 provided in connection with the wire 5” at the lower row, i.e. the lower wire. The third cylinder 3'of the arrangement of the pocket ventilator 10 in connection with the lower wire 5” is the second cylinder 2 of the arrangement of the pocket ventilator 10 in connection with the upper wire 5. The lower wire 5” comprises similarly as the upper wire 5 the entry side 5a'of the wire 5” and the exit _ side 5b'of the wire 5”. The entry side 5a'of the wire 5” is the wire 5 entering the O turn roll 4 and the exit side 5b' of the wire 5” is the wire 5” exiting the turn roll 4. LÖ Although the configuration of the pocket ventilator 10 and the pocket space 100 of ? the second pocket space 100 shown in figure 3 is upside down and inverted relative © 30 to the pocket ventilator 10 and the pocket space 100 of the first pocket space 100, = the configuration of the arrangement according to the invention still applies N because the running direction of the wires and the web remain the same. The web 5 path w runs from the first cylinder 1 at the upper row to the third cylinder 3 at the N lower row which is the first cylinder 1' for the pocket ventilator 10 provided in N 35 connection with the lower wire 5’, from the third cylinder 3 at the lower row to the second cylinder 2 at the upper row and from the second cylinder 2 at the upper row to the fourth cylinder at the lower row which is the second cylinder 2” for the pocket ventilator 10 in connection with the lower wire 5”. The invention has been described above with reference to the examples shown in the figures. However, the invention is in no way restricted to the above examples but may vary within the scope of the claims.
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Claims (14)
1. An arrangement in connection with a drying section of a paper or board machine, the drying section comprising a first cylinder (1), a second cylinder (2), a third cylinder (3), a turn roll (4), a wire (5) arranged to travel from the first cylinder (1) through the turn roll (4) to the second cylinder (2) and a web path (w) from the first cylinder (1) via the turn roll (4) to the third cylinder (3) and through the third cylinder (3) to the second cylinder (2); the first cylinder (1), the second cylinder (2), the third cylinder (3) the web path (w) between the cylinders (1, 2, 3), the turn roll (4) and the wire (5) between the turn roll (4) and the second cylinder (2) forming a pocket space (100), characterized in that the arrangement comprises a pocket ventilator (10) arranged between an entry side (5a) of the wire (5) and an exit side (5b) of the wire (5), the pocket ventilator (10) having a first side (10a) arranged toward the entry side (5a) of the wire (5) and a second side (10b) arranged toward the exit side (5b) of the wire (5), the pocket ventilator (10) comprising: - an exhaust chamber (11) having a first discharge orifice (110) at the second side (10b) of the pocket ventilator (10), the first discharge orifice (110) is arranged to provide a flow path from the pocket space (100) to the exhaust chamber (11) for exhausting air from the pocket space (100); - an inflow chamber (12) having a supply orifice (120) at the second side (10b) of the pocket ventilator (10), the supply orifice (120) is arranged to provide a flow path from the inflow chamber (12) to the pocket space (100) for supplying air into the pocket space (100).
2. An arrangement according to claim 1, characterized in that — the pocket ventilator (10) comprising a second discharge orifice (111) arranged at O the first side (10a) of the pocket ventilator (10), the second discharge orifice (111) ro is arranged to provide a flow path from an entry space (50a) formed between the - wire (5) at the entry side (5a) of the wire (5) and the first side (10a) of the pocket 2 30 ventilator (10) to the exhaust chamber (11).
a a N 3. An arrangement according to claim 1 or 2,characterized in 5 that the exhaust chamber (11) and the inflow chamber (12) are formed in the ON pocket ventilator (10) such that the inflow chamber (12) is next to the turn roll (4) N 35 when the pocket ventilator (10) is arranged between the entry side (5a) of the wire (5) and the exit side (5b) of the wire (5).
4. An arrangement according to any previous claim, characterized in that the pocket ventilator (10) further comprises a first seal element (13) and a second seal element (14) arranged at the second side (10b) of the pocket ventilator (10) on opposite sides of the first discharge orifice (110) such that the first seal element (13) is provided toward the wire (5) at the second cylinder (2) and the second seal element (14) is provided toward the wire (5) ata free space between the supply orifice (120) and the second cylinder (2) such that an exit space (50b) is formed between the wire (5) at the exit side (5b) of the wire — (5) and the second side (10b) of the pocket ventilator (10) and between the first seal element (13) and the second seal element (14).
5. An arrangement according to any of claims 2-4, characterized in that the pocket ventilator (10) further comprises a third seal element (15) and a fourth seal element (16) arranged at the first side (10a) of the pocket ventilator (10) on opposite sides of the second discharge orifice (111) such that the third seal element (15) is provided toward the wire (5) at the first cylinder (1) and the fourth seal element (16) is provided toward the wire (5) ata free space between the first cylinder (1) and the turn roll (4) such that the entry space (50a) is formed between the wire (5) at the entry side (5a) of the wire (5) and the first side (10a) of the pocket ventilator (10) and between the third seal element (15) and the fourth seal element (16).
6. An arrangement according to any previous claim, characterized in that the inflow chamber (12) comprising an equalizing _ plate (112) arranged to divide the inflow chamber (12) into an inlet chamber O section (12a) and a supply chamber section (12b), the egualizing plate (112) LÖ having apertures through the plate (112) for providing a flow path from the inlet ? chamber section (12a) to the supply chamber section (12b), the inlet chamber © 30 section (12a) comprising an inlet arranged to form a flow path from outside of the = pocket ventilator (10) to the inflow chamber (12) and the supply chamber section N (12b) comprising the supply orifice (120) for providing the flow path form the 5 inflow chamber (12) to the pocket space (100).
S N 35 7. An arrangement according to any previous claim, characterized in that the pocket ventilator (10) is connected to a heat recovery system for removing moisture from the air coming from the pocket space (100) such that the exhaust chamber (11) is arranged in a flow connection with the heat recovery system.
8. An arrangement according to claim 7, characterized in that the heat recovery system is further arranged in a flow connection with the inflow chamber (12) for at least partly recirculating moisture air as a hot and dry air back to pocket space (100) through the inflow chamber (12).
9. An arrangement according to any previous claim, characterized in that the exhaust chamber (11) is connected to a suction device for exhausting air from the pocket space (10) through the first discharge orifice (110) to the exhaust chamber (11) and further from the exhaust chamber (11) to an exhaust system, and/or the inflow chamber (12) is connected to an air supply device for supplying air from the air supply device to the inflow chamber (12) and further through the supply orifice (120) to the pocket space (100).
10. Method for removing moisture from a pocket space (100) of a drying section of a paper or board machine, which the drying section comprising a first cylinder (1), a second cylinder (2), a third cylinder (3), a turn roll (4) and a wire (5) travelling from the first cylinder (1) through the turn roll (4) to the second cylinder (2) and a web path (w) from the first cylinder (1) via the turn roll (4) to the third cylinder (3) and through the third cylinder (3) to the second cylinder (2); the first cylinder (1), the second cylinder (2), the third cylinder (3), the web path (w) _ between the cylinders (1, 2, 3), the turn roll (4) and the wire (5) between the turn O roll (4) and the second cylinder (2) forming a pocket space (100), LÖ characterized in that the method comprises: ? arranging a pocket ventilator (10) between an entry side (5a) of the © 30 wire (5) and an exit side (5b) of the wire (5), the pocket ventilator (10) having a = first side (10a) arranged toward the entry side (5a) of the wire (5) and a second N side (10b) arranged toward the exit side (5b) of the wire (5), 5 supplying dry air from an inflow chamber (12) of the pocket ventilator N (10) through a supply orifice (120) at the second side (10b) of the pocket ventilator N 35 to outside of the pocket ventilator (10) and through the wire (5) into the pocket space (100), and discharging moisture air from the pocket space (100) through the wire (5) and through a first discharge orifice (110) at the second side (10b) of the pocket ventilator (10) to an exhaust chamber (11) of the pocket ventilator (10).
11. Method according to claim 10, characterized in that the method further comprises: arranging a first under-pressure zone at an exit space (50b) between the second side (10b) of the pocket ventilator (10) and the exit side (5b) of the wire (5): by arranging a first seal element (13) protruding from the pocket ventilator (10) towards the wire at the second cylinder (2), by arranging a second seal element (14) protruding from the pocket ventilator (10) at the opposite side of the first discharge orifice (110) than the first seal element (13) towards the wire at a free space between the supply orifice (120) and the second cylinder (2), and by discharging air through the first discharge orifice (110) at the second side (10b) of the pocket ventilator (10) to the exhaust chamber (11).
12. Method according to claim 10 or 11, characterized in that — the method further comprises: supplying dry air from the pocket ventilator (10) to the pocket space (100) at a volumetric flow rate of 0,1 - 0,5 m3/s/m, or supplying dry air from the pocket ventilator (10) to the pocket space (100) at a volumetric flow rate of 0,1 — 0,4 m3/s/m.
_
13. Method according to any of claims 10-12, characterized in O that the method comprises: LÖ discharging moisture air from the pocket space (100) and through the ? pocket ventilator (10) at a volumetric flow rate of at least 0,1 - 0,5 m3/s/m, or © 30 discharging moisture air from the pocket space (100) and through the = pocket ventilator (10) at a volumetric flow rate of at least 0,1 - 0,4 m3/s/m.
O 5
14. Method according to any of claims 10-13, characterized in N that the method further comprises: N 35 arranging a second discharge orifice (111) at the first side (10a) of the pocket ventilator (10) for providing a flow path outside of the pocket ventilator
(10) to the exhaust chamber (11); and arranging a second under-pressure zone at an entry space (50a) between the first side (10a) of the pocket ventilator (10) and the entry side (5a) of the wire (5): by arranging a third seal element (15) protruding from the pocket ventilator (10) towards the wire at the first cylinder (1), by arranging a fourth seal element (16) protruding from the pocket ventilator (10) at the opposite side of the second discharge orifice (111) than the third seal element (15) towards the wire at a free space between the first cylinder (1) and the third cylinder (3), and by discharging air through the second discharge orifice (111) at the first side (10a) of the pocket ventilator (10) to the exhaust chamber (11).
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I a a
N 00
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O
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O
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Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FI20205782A FI129176B (en) | 2020-08-04 | 2020-08-04 | An arrangement and a method for removing moisture from a pocket space of a drying section of a paper or board machine |
| CN202021677171.5U CN213571317U (en) | 2020-08-04 | 2020-08-12 | Device in connection with a drying section of a paper or board machine |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FI20205782A FI129176B (en) | 2020-08-04 | 2020-08-04 | An arrangement and a method for removing moisture from a pocket space of a drying section of a paper or board machine |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| FI20205782A1 FI20205782A1 (en) | 2021-08-31 |
| FI129176B true FI129176B (en) | 2021-08-31 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| FI20205782A FI129176B (en) | 2020-08-04 | 2020-08-04 | An arrangement and a method for removing moisture from a pocket space of a drying section of a paper or board machine |
Country Status (2)
| Country | Link |
|---|---|
| CN (1) | CN213571317U (en) |
| FI (1) | FI129176B (en) |
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2020
- 2020-08-04 FI FI20205782A patent/FI129176B/en active IP Right Grant
- 2020-08-12 CN CN202021677171.5U patent/CN213571317U/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| CN213571317U (en) | 2021-06-29 |
| FI20205782A1 (en) | 2021-08-31 |
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