EP0997697A2 - Apparatus for drying and cooling freshly printed paper webs - Google Patents

Abstract

Nozzles are arranged along the path followed by the strip through the drier and cooler. They discharge hot drying gas or cold air onto the strip. The after-burner chamber is connected to a suction pipe extracting the drying gas enriched by volatile oil or resin, also to feed pipes for clean gas to the nozzles and to an exhaust pipe for surplus clean gas. An absorption-type refrigerator (4) contains a boiler (14) for the concentrated refrigerating solution and an evaporator (21) for liquid refrigerating medium, being thermally connected to the drier (1) and cooler (3). Heat extracted from the clean gas flowing through the exhaust pipe (16) is fed to the boiler and that from the cold air inside the cooler or the fresh air flowing into the cooler is fed to the evaporator.

Description

The invention relates to a device according to the preamble of the claim 1.

A device with the features of the preamble is known from EP 0 543 439 B1 known.

EP 0 396 173 B1 is particularly concerned with a cooler for such a cooler Contraption. As can be seen from the introduction to this document, the paper leaves the dryer with a temperature of, for example, 130 ° C. At this temperature the evaporation has not yet stopped and adheres to the paper a boundary layer of oily vapors. If the dryer, as usual, a Is immediately downstream of the roller cooler, the vapors condense on the Cooling rollers and form a film that smears the paper. This evil is corrected according to the font mentioned that behind the dryer An air cooler is initially arranged in which the web is floating, as in the dryer between blowing nozzles. The air cooler is in chambers divided. Ambient air of around 20 ° C is used as cooling air, which is caused by a Feed opening introduced into the last chamber and in the opposite direction to continuous path from chamber to chamber. In the air cooler the web is cooled to an intermediate temperature, for example 90 ° C, at which the Evaporation is significantly reduced. With this intermediate temperature, this happens Paper to a downstream roller cooler.

DE-AS 1 293 163 describes a multicolor printing line with several in a row switched printing stations, for example offset machines. Behind everyone Printing station, the web to be printed passes through a dryer and a cooler. The cooler consists essentially of a hood and one arranged therein Blow box with nozzle bottom. A line for feeding leads into the blow box of cooling air, which is usually supercooled. Due to the effective recooling be prevented that the resins heated during the drying process liquefy or soften and in this state on the pressure rollers or other Store the accessories of the following machines.

From US-PS 3 328 997 is a heat treatment device for strip material known, which consists of a heating zone and a flow direction on it subsequent cooling zone. The web to be treated is both by the Heating zone, as well as horizontally back and forth through the cooling zone. The Treatment line consists of three straight lines arranged one above the other Sections and two 180 degree arches. One arch connects to one End the lower section with the middle section, the other arch at at the other end the middle section with the upper section. Along the rectilinear sections of the line are blow nozzles below and above the web arranged, which keep the continuous path in suspension. In the field of Arches are made with spiral strips, the semi-cylindrical wrapping surfaces of which Support nozzles are equipped, a contact-free deflection is guaranteed. The meandering configuration of the treatment section results in a short overall length a relatively strong cooling effect.

From DE 43 36 364 A1 it is known in a device for cooling Flat glass, which with nozzles for blowing the glass on both sides and with Fans for circulating the treatment gas is equipped inside the Treatment room, preferably in the intake ducts of the fans, Arrange cooling register.

The invention has for its object a device with the in the preamble of the features specified to improve so that with low Operating costs a much stronger cooling effect is achieved. The paper web should cooled with air to a temperature significantly below 90 ° C, preferably to a temperature with which they can be cooled without additional cooling downstream station, in particular a folder, can be supplied, d. H. to a temperature of 20 to 30 ° C. In this way it should be possible reduce the number of chill rolls required, preferably even that To make the conventional roller cooler dispensable.

This object is achieved by the characterizing features of claim 1. All of the heat required for cooling becomes the exhaust gas flow taken. This keeps costs down. An important advantage of Invention is to be seen in the fact that the cooled paper largely by longitudinal waves free is. In contrast, shows in known devices, the cooler with is equipped with several cooling rollers, the finished product is always a clear one Waviness, the removal of which has not yet been satisfactorily achieved. If if a downstream roll cooler is required at all, that comes Paper in contact with the cold rollers only after it has reached a temperature cooled, in which evaporation of oily substances is excluded. The rollers therefore remain completely free of condensate deposits.

Another advantageous feature is the subject of claim 2.

Figur 1 zeigt eine Vorrichtung gemäß der Erfindung in Seitenansicht.

Figur 2 zeigt die gleiche Zeichnung wie Figur 1, wobei an markanten Punkten die Betriebstemperaturen eingetragen sind; die Bezugszeichen wurden der Deutlichkeit halber fortgelassen.

Figur 3 zeigt für ein anderes Ausführungsbeispiel einen Kühler.

The drawing serves to explain the invention using schematically illustrated exemplary embodiments.

Figure 1 shows a device according to the invention in side view.

FIG. 2 shows the same drawing as FIG. 1, the operating temperatures being entered at prominent points; the reference numerals have been omitted for the sake of clarity.

Figure 3 shows a cooler for another embodiment.

The device illustrated in FIG. 1 also includes a dryer 1 Afterburner 2, a cooler 3 and an absorption refrigeration system 4, which in the Drawing is enclosed by a dashed circle. A to be treated freshly printed paper web passes through dryer 1 and then immediately after cooler 3 connected from there downstream roller cooler 6, the few, preferably at most two Has cooling rollers.

The dryer 1 is constructed in a modular manner from a plurality of chambers 1a to 1d are lined up in the direction of flow. In the chamber 1a are like in the Drawing only indicated - in a known manner above and below the Paper web 5 carrying nozzles 7 for contactless guiding of the paper web arranged. The support nozzles 7 are via a system of channels 8 on the pressure side a fan 9 connected. This is on the suction side with the interior of the Chamber 1a in open communication. The chambers 1b to 1d are essentially equipped analog.

There is a vertical wall 10 between each two adjacent chambers 1a to 1d provided with a slot for the continuous paper web 5 and possibly with an opening 11 is provided. In the last - seen in the direction of flow Chamber 1d houses a suction fan 12, which on the suction side Connection line 13 communicates with the interior of the chamber 1a. On the pressure side, the suction fan 12 opens into the afterburning chamber 2 with the inlet-side chamber 1a and possibly with further chamber 1b, 1c, 1d of the Dryer 1 through openings 15 in connection with which the dryer 1 in Operation hot clean gas is supplied. To remove excess clean gas is an exhaust pipe 16 is connected to the afterburning chamber 2.

The cooler 3, like the dryer 1, is made up of several strings Chambers 3a to 3c constructed. Between the individual chambers 3a to 3c are - analog to the dryer 1- partitions 10 with slots for continuous paper web 5 and possibly with openings 11. The chamber 3a, the connects directly to the dryer 1, is analogous to the chambers 1a to 1d of the Dryer 1 with a circulating air system, not shown in the drawing equipped, which has carrying nozzles, channels and a circulating air fan. The the same applies to chamber 3b. The outlet-side chamber 3 c also has one System of support nozzles 7. These are connected via a channel system to a line 17 to the Supply of cooled fresh air connected. In the individual chambers 3a to 3c cooling registers 18 are accommodated.

As is known per se, the absorption refrigeration system 4 comprises a cooker 19, one Condenser 20, an evaporator 21 and an absorber 22. For heating the Kochers 19 serves a heating coil 23. This is in a heating medium circuit integrated, which via the heat-absorbing flow channel Heat exchanger 24 is guided. The heat-emitting flow channel of the Heat exchanger 24 is on one side to the exhaust duct 16 Afterburner chamber 2 connected, on the other side to a chimney 25. Im Cooker 19 is made from a refrigerant solution, for example an ammonia solution, gaseous refrigerant expelled at elevated temperature and pressure. The gas is fed to the condenser 20 via a line 26. This is with a cooling coil 27 equipped with a cooling water circuit with a Recooler 28 is connected. By exchanging heat with the pumped The gaseous refrigerant is liquefied in cooling water. In this state it will fed to the evaporator 21 via an expansion valve 29. There is one in it Rohrachlange 30 arranged, both with a via a heat transfer circuit Cooling registers 18 of the individual chambers 3a to 3c of the cooler 3 as well a heat exchanger 31 is connected, which in the fresh air line 17 of the cooler 7 is integrated.

From the evaporator 21, the low-pressure refrigerant vapor passes to the Absorber 22, where it is absorbed in low-concentration refrigerant solution. The absorption heat released in the process is dissipated through a coil 32, which is connected to the recooler 28 via pipes. This Pipes not shown in the drawing for the sake of clarity are, the connection points A, B with the points A ', B' of the already mentioned cooling water circuit of the condenser 20. Enriched Refrigerant solution is pumped into the cooker 19 under increased pressure pumped back while at the same time out of the cooker 19 via a control valve 34 low-refrigerant solution is supplied to the absorber 22. In a heat exchanger 35 the enriched colder solution is replaced by the weaker, warmer solution in the Pre-warmed.

In the dryer 1, hot treatment gas, which is caused by Fans 9 is circulated, blown onto the continuous paper web 5, the dried in this way and kept in suspension. Excess, with evaporated solvent-enriched treatment gas flows through the slot and the opening 11 of the partition 10 against the direction of travel of the web of Chamber to chamber and is by the fan 12 via the connecting line 13 sucked out of the first chamber 1a and fed to the afterburning chamber 2. There it is burned together with the supplied fuel gas and in this way freed from solvent. Part of the pure gas thus obtained is via the Openings 15 are returned to the dryer 1 as treatment gas. Excess clean gas is in a not shown in the drawing Heat exchanger by heat exchange with the treatment gas, which the Afterburning chamber 2 is supplied via the fan 12, initially to about 350 ° C. cooled, passed through the exhaust pipe 16 to the heat exchanger 24, therein Heat exchange with the heating medium of the cooker 19 cooled to about 180 ° C and finally expelled through the chimney 25 into the atmosphere. The cooker 19 will heated in this way by the heat that is extracted from the clean gas.

In the cooler 3 is the paper web, which the dryer with a temperature of about Leaves 130 ° C, cooled by blowing cold air and suspended held. In the chamber 3a immediately following the dryer 1 cold air through the aforementioned, not shown in the drawing Circulated fans. The circulated air flow sweeps the cooling register 18 and is kept constantly at a low temperature. The same goes for the adjoining chamber 3b. The outlet-side chamber 3c becomes fresh air supplied by the heat exchanger 31 with the cold heat transfer medium Example water or brine, the absorption refrigeration system 4 has cooled. The heat, that of the cold air circulating inside the cooler 3 through the cooling registers 18 is withdrawn, the heat transfer medium through the coil 30 Evaporator 21 supplied. The same thing happens with the heat in the Heat exchanger 31 is withdrawn from the fresh air.

The cold air circuits of the individual chambers 3c, 3b, 3a each become a partial flow branched off and the one opposite to the direction of travel of the paper web 5 Chamber fed, as indicated in the drawing by small arrows. The one out The partial stream branched off from the chamber 3a reaches the chamber 1d of the dryer 1 and mixes there with the hot treatment gas.

With sufficient capacity of the absorption refrigeration system 4 can at the points C, D other lines can be connected to other units cool, in particular the roller cooler 6 or the rollers of the Dryer 1 upstream printing machine.

In the modified cooler 36 shown in Figure 3, the interior of the Housing by horizontal false ceilings 37 in three levels one above the other arranged chambers 36a, 36b, 36c divided. The paper web 5 passes through a meandering treatment section, consisting of three one above the other arranged straight line sections 38a, 38b, 38c and two 180 ° bends 39, 40. The one arch 39 connects the lower to the middle, in reverse Direction traveled section, the other the middle with the upper section of the route. Along the straight line sections 38a, 38b, 38c support nozzles 7 are arranged above and below the paper web. In the area of the arches 39, 40 turning stations 41, 42 are provided which have a semicircular shape Cross section. The paper web is facing a semi-cylindrical Shell surface, which is provided with nozzle slots, which also in the area of Arches 39, 40 ensure contact-free guidance.

The support nozzles 7 of the lower chamber 36a are connected via a channel system 8 to the Pressure side of a fan 9 connected. At a branch 43 of the duct system the turning station 41 connected. On the suction side, the fan 9 is connected to the Interior of chamber 38a in communication. In the chamber 38a there is a cooling register 18 arranged, which is analogous to Figure 1 in the heat transfer medium Absorption refrigeration system is integrated.

The middle chamber 38b has an analog one, not shown in the drawing Furnishing.

The support nozzles 7 of the upper chamber 38 are jointly connected to a fresh air line 17 connected, as described in connection with Figure 1 via a Heat exchanger with the heat transfer circuit of an absorption refrigeration system in Connection is established.

Claims (2)

Device for drying and cooling freshly printed, continuously moving, in particular floating paper webs with the following features: nozzles for blowing hot drying gas or cold air onto the continuous paper web are arranged in a dryer and a cooler following the dryer in the direction of flow; an afterburning chamber is connected on the one hand to a suction line for the drying gas enriched with volatile oil or resinous substances from the inside of the dryer, on the other hand to supply lines for clean gas to the nozzles of the dryer and to an exhaust gas duct for excess clean gas,
characterized by an absorption refrigeration system (4) which comprises, inter alia, a cooker (19) for concentrated refrigerant solution and an evaporator (21) for liquid refrigerant and is thermally linked to the dryer (1) and the cooler (3, 36) in this way , that the cooker (19) is supplied with heat which is extracted from the clean gas flowing through the exhaust gas duct (16) and that the evaporator (21) is supplied with heat which is extracted from the cold air located inside the cooler (3, 36) and / or the fresh air flowing in to the cooler (3, 36). Device according to claim 1, characterized by a zigzag shape in the cooler (36) current treatment line, consisting of several in straight line sections (38a, 38b, 38c) and arches (39, 40), each with two adjacent straight lines Route sections are connected at one end.

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