Dryer for providing drying air in a printing process of a printing press and method for operating this dryer

Abstract

The invention relates to a dryer for providing drying air in the printing process of a printing press, comprising a heat exchanger, wherein the heat exchanger is designed to heat the drying air to be provided in the printing process of the printing press, wherein the heat exchanger is designed as a water / air heat exchanger, wherein the heat exchanger is designed to transfer the heat from water of a process separate from the printing process of the printing press to the drying air to be provided in the printing process of the printing press.A method for operating this dryer is also described, in which the heat exchanger heats the drying air to be provided in the printing process of the printing press by means of heat transferred by water, preferably using water from a process carried out in a combined heat and power plant or water from a process carried out in a biomass power plant, in particular in a wood chip power plant or water from a district heating network.

Description

[0001] The invention relates to a dryer for providing drying air in a printing process of a printing press according to the preamble of claim 1 and a method for operating this dryer according to the preamble of claim 8.

[0002] In an industrial printing process, liquid printing fluids, either in the form of a printing ink or a varnish, are applied to a sheet-shaped or web-shaped substrate using a printing press. These printing fluids are often water-based, meaning a colorant, i.e., a coloring agent, is dissolved in water. To prevent the applied printing fluid from smearing or contaminating other items during further transport and / or processing of the substrate, the printed substrate is dried in a dryer as soon as possible after application to evaporate most of the water contained in the printing fluid. These dryers typically use drying air, which is directed onto the surface of the printed substrate, often with the assistance of a fan. The drying air is usually...The dryer uses air heated to a temperature between 50°C and 150°C, particularly hot air of 100°C and above. The dryer draws the air to be heated, for example, by means of a fan, from a room surrounding the dryer, such as a printing room where the printing press is located. This air drawn from the room surrounding the printing press has a temperature of, for example, up to 30°C. Often, the temperature of this incoming air is between 10°C and 25°C. The air, which is directed by the dryer onto the surface of the printed substrate as drying air, is heated, for example, by means of a heating element, usually electrically operated, located in the dryer and / or supported by at least one electrically operated infrared heater.In any case, warming or heating the air supplied to the dryer requires a large amount of energy, which is not insignificant in the cost balance of the printing process carried out by the printing press.

[0003] DE 10 2011 084 815 A1 discloses a printing press with a dryer unit and waste heat recovery system as well as a method for optimizing waste heat recovery on a printing press, wherein a waste heat recovery system includes a heat exchanger which heats air and makes it available for a dryer unit.

[0004] The invention is based on the objective of creating a dryer for providing drying air in a printing process of a printing press and a method for operating this dryer, wherein the drying air is heated in an energy-efficient manner.

[0005] The problem is solved according to the invention by the features of claim 1 and by the features of claim 8. The dependent claims relate to advantageous embodiments and / or further developments of the solution found.

[0006] The advantages achievable with the invention lie particularly in the fact that, in a dryer used to supply drying air in a printing press process, at least a large portion of the electrical energy required to heat the drying air can be saved. The solution found provides the dryer with at least one additional heat source, the use of which can significantly reduce or even completely eliminate the previously required electrical energy for supplying drying air.

[0007] An embodiment of the invention is shown in the drawing and is described in more detail below.

[0008] They show: Fig. 1. A dryer supplying drying air to a printing press, with a heat exchanger for heating the drying air.

[0009] In the Fig. Figure 1 is a schematic and simplified example, without limitation, of a printing press designed as a sheet-fed printing press, wherein the printing press is associated with at least one dryer 17 with at least one heat exchanger 36. The heat exchanger 36 heats air supplied to the dryer 17 from the environment of the printing press via an air supply duct 37 and directs this air as drying air to a drying section provided in the printing press, extending along the transport path of the substrate. In a sheet-fed printing press, the substrate is always in the form of a sheet.

[0010] The one in Fig. An exemplary sheet-fed printing press, shown in the transport direction T of the sheets, first has a sheet feeder 01 in which a first stack 02 of sheets is ready for processing. The sheets are preferably rectangular substrates made of paper, cardboard, or corrugated board. Paper, cardboard, and corrugated board differ in their respective basis weight, i.e., the weight in grams per square meter of these sheets. Paper has a basis weight between 30 g / m². 2 and 150 g / m² 2 Cardboard has a basis weight between 150 g / m² 2 and 600 g / m² 2 and cardboard with a basis weight of more than 600 g / m² 2 The substrate can also be a plastic material and / or a thin sheet made of, for example, a metallic material. The sheet feeder 01 can also be a magazine feeder comprising several first stacks 02.

[0011] In the case of a printing press designed as a sheet-fed printing press, a sheet separator 03, also referred to as a suction head, grasps each of the stacked sheets successively from above and feeds these sheets, e.g., by means of a first vibrating gripper 04 and optionally a transfer drum 34 cooperating with the first vibrating gripper 04, in a sequence of separated sheets to, e.g., a first coating unit 05, wherein this first coating unit 05 is designed, e.g., as a primer application unit. The first coating unit 05 has a transport cylinder 06, designed, e.g., as a printing cylinder, and, e.g.,A printing cylinder 07, cooperating with this transport cylinder 06, has an application roller 08 attached to or at least adjustable against this printing cylinder 07, preferably in the form of an anilox roller, wherein at least one doctor blade 09 or a chambered doctor blade system 09 extends in the axial direction of the application roller 08 for optimal metering of a coating material to be applied to the surface of the sheets. The transport cylinder 06 transports the sheets held on its outer surface along a curved, in particular arc-shaped, transport path. The first coating device 05 applies the coating material, e.g., a primer, to one of the two sides of the sheets either completely or only at certain, i.e., previously determined, locations. The sheets are then transferred from the transport cylinder 06 of the first coating device 05, e.g.,by means of a preferably continuously circulating first gripper system 11, in particular a first chain conveyor, and e.g. at least one first conveyor belt 12, the sheets are transferred to a printing unit, e.g. designed as a non-impact printing unit 13, wherein the first gripper system 11 and the first conveyor belt 12 cooperate when transferring the sheets to the non-impact printing unit 13, such that the first gripper system 11 delivers the sheets to the first conveyor belt 12, which has a linear transport section, and the sheets are transferred to the non-impact printing unit 13 from the first conveyor belt 12. The first conveyor belt 12 is preferably designed as a continuously circulating endless belt. In an advantageous embodiment, a first dryer 14 is provided in the area of ​​the first gripper system 11 for drying the sheets coated in the first coating unit 05, wherein this dryer 14 is e.g.is designed as a hot air dryer and / or as a dryer that dries using IR radiation or UV radiation.

[0012] The non-impact printing unit 13 comprises, for example, several, in particular at least four, independently controllable inkjet printing units, each of which applies a different printing color to the side of the sheet previously coated, for example, in the first coating unit 05, to create a preferably multi-colored printed image. In the sheet-fed printing press described here as an example, the non-impact printing unit 13 preferably has a second conveyor belt 16, so that the sheets are printed by the inkjet printing units while lying on this second conveyor belt 16. The second conveyor belt 16 is preferably designed as a continuous, circulating belt. Downstream of the non-impact printing unit 13, in the transport direction T of the sheets, a second dryer 17 is arranged for drying the printed sheets, this second dryer 17 also being, for example,The second dryer 17 is designed as a hot air dryer and is optionally supported by a radiation source emitting IR radiation. The second dryer 17 has a transport device 18 which transports the sheets translationally in a horizontal position, i.e., along a linear transport path. This transport path connected to the second dryer 17 is also referred to as the drying path, since it is of particular importance for the present invention. The transport device 18 of the second dryer 17 is located in the [unclear - possibly a diagram or section]. Fig. In the sheet-fed printing press shown as an example, a third conveyor belt 18 is configured. This third conveyor belt 18 is also preferably configured as a continuous, circulating belt. The transport device 18 of the second dryer 17 in this example transfers the dried sheets preferably to a suction belt table 19, which is typically located directly downstream. From there, the sheets are transferred, for example, by means of a second vibrating gripper 21 and optionally a transfer drum 33 cooperating with the second vibrating gripper 21, to a second coating device 22. The second coating device 22 is configured, for example, as a coating device, wherein this second coating device 22 applies a coating material, e.g., a varnish, in particular to a printed image previously created in the non-impact printing device 13. The second coating device 22 again has, for example, a transport device for the sheets to be transported.A transport cylinder 23 designed as a printing cylinder, wherein, for example, a printing cylinder 24 with an application roller 26 attached to or at least attachable to this printing cylinder 24, preferably in the form of an anilox roller, interacts with this transport cylinder 23, wherein at least one doctor blade 27 or a chambered doctor blade system 27 extends in the axial direction of the application roller 26. The first transport belt 12 and / or the second transport belt 16 and / or the third transport belt 18 are each preferably designed as a circulating flat belt and furthermore preferably as a suction belt, wherein the suction belt has a perforation at least in sections.

[0013] The sheets are then transported from the transport cylinder 23 of the second coating unit 22, e.g., by means of a preferably continuously rotating second gripper system 28, in particular a second chain conveyor, to a delivery unit 29, wherein the sheets processed in this exemplary sheet-fed printing press described are placed by the second gripper system 28 in the delivery unit 29, preferably in a second stack 32. In an advantageous embodiment, a third dryer 31 is provided in the area of ​​the second gripper system 28 for drying the sheets coated in the second coating unit 22, wherein this third dryer 31 is designed, e.g., as a hot air dryer and / or as a dryer that dries by IR radiation or by UV radiation. The delivery unit 29 can also be designed as a multi-stack delivery unit comprising several second stacks 32.

[0014] The one in Fig. The sheet-fed printing press shown as an example is a digital printing press designed for use in an industrial printing process, particularly for the mass production of printed materials. This sheet-fed printing press sequentially feeds individual sheets from the sheet feeder 01 to the delivery 29 at a transport speed of several thousand sheets per hour, e.g., between 2,500 and 10,000 sheets per hour. Along at least one of the linear transport paths, adjacent sheets in their transport direction T, i.e., sheets that follow directly one another in the sequence, are separated from each other by a gap. This gap is significantly smaller than the length of the sheets extending in the transport direction T and is only a few millimeters, e.g., approximately 20 mm.

[0015] According to the invention, the heat exchanger 36, which heats or warms air, e.g., for the second dryer 17, and thus produces drying air, is designed as a water / air heat exchanger, wherein the heat exchanger 36 is configured to transfer heat from water in a process separate from the printing process of the printing press to the drying air to be provided in the printing process of the printing press. In particular, it is provided that process heat-carrying water from an industrial plant, process heat-carrying water from a process carried out in a combined heat and power plant, process heat-carrying water from a process carried out in a biomass-fired power plant, in particular in a wood chip-fired power plant, or water from a district heating network is used.This heat-transporting water is supplied via a piping system 38 to an inlet of the heat exchanger 36 and fed into the respective heat exchanger 36 of the dryer 17. In particular, the water supplied to the respective heat exchanger 36 via the inlet from an industrial plant, or the water supplied to the respective heat exchanger 36 via the inlet from a combined heat and power plant, or the water supplied to the respective heat exchanger 36 via the inlet from a biomass-fired power plant, is, for example, cooling water used in the respective process, which has been heated by the respective process in the industrial plant, in the combined heat and power plant, or in the biomass-fired power plant to a temperature range between 30°C and 60°C, or even heated to over 60°C.It can also be provided that hot water from a hot water system is supplied to the heat exchanger 36 in question, where, in thermal engineering, hot water refers to liquid water at a temperature of 110°C or higher, whereby a corresponding pressure, which must be higher than the saturated vapor pressure, prevents the water from boiling and ensures that the water remains in liquid form even above 100°C. Hot water is used, for example, in a district heating system and is conveyed in a piping system 38 of a district heating network.

[0016] In the supply air duct 37, through which air to be heated is supplied from the environment of the printing press to the relevant heat exchanger 36 of the dryer 17, a fan 39 is arranged, for example, for air intake. Likewise, a valve 41 is arranged, for example, in the supply air duct 37 to control the volume of air flowing to the relevant heat exchanger 36 of the dryer 17. In a duct 42 that conducts the air heated by the relevant heat exchanger 36 of the dryer 17, i.e., the drying air, to the drying section, another fan 43 is arranged, for example, to promote the volume flow of the drying air. The respective flow direction of the air to be heated and the heated or dried air is specified in the Fig. 1 each indicated by a directional arrow.

[0017] To obtain information about the temperature of the air heated or warmed by the heat exchanger 36 of the dryer 17, or the drying air, a temperature sensor 44 is preferably arranged in or near the duct 42 that conducts the drying air to the drying section. In an advantageous embodiment of the dryer 17, which includes the heat exchanger 36, a control unit 46 is provided that receives measured values ​​from the temperature sensor 44 and, in particular, controls or regulates, based on these measured values, e.g., the valve 41 and / or the fan 39 arranged in the supply air duct 37 and / or the fan 43 arranged in the duct 42 for supplying the drying air to the drying section.A control system implemented by the control unit 46 ensures that an optimal setpoint for the drying air is maintained throughout the entire printing process performed by the printing press. The fan 39, located in the supply air duct 37, and the fan 43, located in the duct 42 for supplying the drying air to the drying section, are, for example, both housed in a cabinet associated with the printing press.

[0018] The control system implemented by the control unit 46 can, for example, be configured such that the volume flow of the water supplied to the relevant heat exchanger 36 via the inlet – be it water from an industrial plant, a combined heat and power plant, a biomass power plant, or a hot water system – is reduced, for example, by a valve system arranged in the inlet to the heat exchanger 36 and / or in the piping system 38, in particular designed as a throttling device, when the dryer air heated by the relevant heat exchanger 36 has a higher temperature, as measured by the temperature sensor 44, than the setpoint temperature set for the dryer 17. This setpoint temperature was previously supplied to the control unit 46 for the purpose of this control and / or set in the control unit 46. This control system is used, for example,It is used when the amount of drying air required in the drying process has to be reduced due to pressure process conditions and / or the setpoint temperature of the drying air has to be lowered due to pressure process conditions and / or the temperature of the water fed into the relevant heat exchanger 36 is higher than is required to warm or heat the drying air.

[0019] To generate the required drying air from the air supplied to the dryer 17, particularly via the supply air duct 37, several heat exchangers 36 can be arranged in the dryer 17, wherein process heat-carrying water from different sources, i.e., from different heat generators, is supplied to these heat exchangers 36. For example, process heat-carrying water from an industrial plant is fed into a first heat exchanger 36, and / or process heat-carrying water from a process carried out in a combined heat and power plant is fed into a second heat exchanger 36, and / or process heat-carrying water from a process carried out in a biomass power plant, particularly a wood chip power plant, is fed into a third heat exchanger 36, and / or water from a district heating network is fed into a fourth heat exchanger 36.These heat exchangers 36 are preferably arranged sequentially in the dryer 17 along the path of the air flowing through it, thus forming different heating stages. It can also be provided that a heating element 47 is arranged, particularly in or near the channel 42 of the dryer 17 that conducts the drying air to the drying section. This heating element 47 is switched on or off by the control unit 46 as needed, e.g., depending on the measured values ​​of the temperature sensor 44. The heating element 47 can thus be operated in a pulsed manner by the control unit 46. It can also be provided that only a single heat exchanger 36 is arranged in the dryer 17, but that heat-carrying water from several different sources, i.e., from different heat generators, is supplied via the inlet of the heat exchanger 36. This supply of heat from different sources can also be, for example,The valve system arranged in the piping system 38 may be controlled or regulated by the control unit 46 in the manner described above. Reference symbol list 01 Bow feeder 02 first stack 03 Sheet separator 04 first swing gripper 05 first coating facility 06 Transport cylinders 07 Printing cylinder 08 Application roller 09 Doctor blade; chamber doctor blade system 10 - 11 first gripper system 12 conveyor belt 13 Non-Impact Printing Device 14 first dryer 15 - 16 conveyor belt 17 second dryer 18. Transport equipment; conveyor belt 19 Suction belt table 20 - 21 second swing gripper 22 second coating unit 23 transport cylinders 24 printing cylinders 25 - 26 Application roller 27 doctor blades; chamber doctor blade system 28 second gripper system 29 Display 30 - 31 third dryer 32 second stack 33 Transfer drum 34 Transfer drum 35 - 36 heat exchangers 37 Supply air duct 38 Piping system 39 Fan 40 - 41 Valve 42-channel 43 Fan 44 Temperature sensor 45 - 46 Control unit 47 heating registers T Transport direction QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2011 084 815 A1

[0003]

Claims

[1] Dryer (17) for providing drying air in a printing process of a printing press, comprising at least one heat exchanger (36), wherein the heat exchanger (36) in question is designed to heat the drying air to be provided in the printing process of the printing press, characterized by that the heat exchanger (36) in question is designed as a water / air heat exchanger, wherein the heat exchanger (36) in question is designed to transfer the heat from water of a process separate from the printing process of the printing press to the drying air to be provided in the printing process of the printing press. [2] Dryer (17) according to claim 1, characterized by that the water supplied to the water / air heat exchanger in question from the process separate from the printing process of the printing press is cooling water from an industrial plant or from a combined heat and power plant or from a biomass heating plant or from a district heating plant. [3] Dryer (17) according to claim 1 or 2, characterized by that a fan (39) and / or a valve (41) influencing air intake is / are arranged in a supply air duct (37) supplying air from the surroundings of the printing press to the heat exchanger (36) in question. [4] Dryer (17) according to claim 1 or 2 or 3, characterized by that a fan (43) is arranged in a duct (42) conducting the drying air from the heat exchanger (36) in question to a drying section arranged in the printing press and / or a temperature sensor (44) is arranged in or near the duct (42) conducting the drying air to the drying section. [5] Dryer (17) according to claim 4, characterized by that a control unit (46) is provided, wherein the control unit (46) records measured values ​​detected by the temperature sensor (44). [6] Dryer (17) according to claim 5, characterized bythat the control unit (46) is designed such that, depending on the measured values ​​detected by the temperature sensor (44), it controls or regulates the valve (41) arranged in the supply air duct (37) and / or the fan (39) arranged in the supply air duct (37) and / or the fan (43) arranged in the duct (42) for supplying the drying air to the drying section and / or switches on or off a heating register (47) arranged in the dryer (17). [7] Dryer (17) according to claim 4 or 5 or 6, characterized by that the fan (39) arranged in the supply air duct (37) and the fan (43) arranged in the duct (42) for supplying the drying air to the drying section are arranged together in a cabinet assigned to the printing machine. [8] Method for operating a dryer (17), wherein the dryer (17) provides drying air in the printing process of a printing press, wherein the dryer (17) is operated with at least one heat exchanger (36) heating the drying air, characterized by that a water / air heat exchanger is used as the heat exchanger (36), wherein the heat exchanger in question (36) heats the drying air to be provided in the printing process of the printing press by means of heat transferred by water, wherein water from at least one process separate from the printing process of the printing press is used. [9] Method according to claim 8, characterized by that water from a process carried out in an industrial plant and / or water from a process carried out in a combined heat and power plant and / or water from a process carried out in a biomass cogeneration plant, in particular in a wood chip cogeneration plant and / or water from a district heating network is used. [10] Method according to claim 8 or 9, characterized by that the respective heat exchanger (36), which is designed as a water / air heat exchanger, is supplied with warm water in a temperature range between 30°C and 60°C or water heated to over 60°C or hot water with a temperature of 110°C or more and / or that air supplied to the dryer (17) from an environment of the printing press is heated to a temperature in the range between 50°C and 150°C and is then passed as drying air to a drying section arranged in the printing press. [11] Method according to claim 8 or 9 or 10, characterized by that a plurality of heat exchangers (36) are arranged in the dryer (17), wherein water transporting process heat is supplied to these heat exchangers (36) from different heat generators. [12] Method according to claim 11, characterized bythat water transporting process heat from an industrial plant is fed into a first heat exchanger (36) and / or water transporting process heat from a process carried out in a combined heat and power plant is fed into a second heat exchanger (36) and / or water transporting process heat from a process carried out in a biomass combined heat and power plant is fed into a third heat exchanger (36) and / or water from a district heating network is fed into a fourth heat exchanger (36). [13] Method according to claim 8 or 9 or 10 or 11 or 12, characterized by that the dryer (17) provides drying air to a printing press designed as a sheet-fed printing press, in particular to a printing press designed as a digital printing press. [14] Method according to claim 8 or 9 or 10 or 11 or 12 or 13, characterized byin that a volume flow of the water supplied to the relevant heat exchanger (36) via an inlet is reduced by a valve system arranged in the inlet to the relevant heat exchanger (36) and / or in a piping system (38) connected to the inlet of the relevant heat exchanger (36) by a control unit (46) controlling this valve system, when the dryer air heated by the relevant heat exchanger (36) has a higher temperature, measured by a temperature sensor (44) arranged in the relevant heat exchanger (36), than a setpoint temperature set for the dryer air of the dryer (17), wherein this setpoint temperature was previously supplied to the control unit (46) and / or set in the control unit (46).

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