Device for producing a corrugated board and method for operating such a device

Abstract

The invention relates to a method for operating a device (2), the device (2) having a cardboard device (4) for producing a cardboard (6), the device (2) having a printing device (8) for printing a paper layer (10) with a printed product, the device (2) having a heat engine (12) for generating a thermal power (Pth) and an electrical power (Pel), the cardboard device (4) and the printing device (8) forming a composite material, the thermal power (Pth) and the electrical power (Pel) are thus jointly provided by the heat engine (12). A corresponding device (2) is also provided.

Description

Technical Field

[0001] The invention relates to a method for operating a plant suitable for manufacturing corrugated board and to a corresponding plant. Background Art

[0002] In the manufacture of corrugated board, several paper layers are joined together by a corrugating machine to form a corrugated board web, which is then optionally assembled further. For example, to produce double-layer (also called two-part) corrugated board, two paper layers are in each case corrugated by slotting rollers and then alternately bonded with three non-corrugated paper layers to form a stack. The corrugated board web is finally assembled and, for example, divided into individual batches. In the manufacture of corrugated board, the different processing stations of the corrugating machine require corresponding energy. On the one hand, electrical power (current) is required to drive the corrugating machine, and on the other hand, thermal power (heat) is required for drying or generating steam at different points, for example when producing the corrugated web by slotting rollers. In this case, the demand for thermal power usually significantly exceeds the demand for electrical power.

[0003] In principle, it is desirable to make the manufacture of corrugated board as energy-efficient and economical as possible and to make the best possible use of the primary energy used to operate the corrugated board plant for this purpose. The concept of combined heat and power (CHP) or even combined cooling, heating and power (CCHP) generally offers the advantage that the primary energy used (e.g. natural gas) is essentially completely converted into heat and electricity in one integrated process and can therefore be used efficiently. However, the ratio of electrical power to thermal power achieved in this case cannot be adjusted at will, but is predetermined by the conversion process of the primary energy, so that combined heat and power or combined cooling, heating and power may not necessarily be the best fit for every process. Summary of the invention

[0004] Against this background, one object of the present invention is to make the production of corrugated board as energy-efficient as possible. In particular, a combined heat and power process or even a combined cooling, heating and power process will be used here. To this end, a correspondingly improved device for producing corrugated board and a method for operating the same will be provided.

[0005] According to the invention, this object is achieved by a method having the features of claim 1 and a device having the features of claim 18. Advantageous embodiments, improvements and variants are the subject matter of the dependent claims. The detailed descriptions relating to the method also apply to the device and vice versa. In the case of the steps of the method described below, an advantageous design of the device is obtained in that the device is designed to carry out one or more of these steps. For this purpose, the device in particular has a correspondingly designed control unit.

[0006] The core idea of ​​the invention is in particular to combine a corrugating machine with a printing machine and then operate it together with a heat engine. In other words, the corrugating machine, the printing machine and the heat engine are coupled to each other in terms of energy. This is based on the recognition that the ratio of the thermal power to the electrical power (i.e. the power ratio) of the heat engine particularly best reflects the total demand for thermal power and electrical power of the corrugating machine combined with the printing machine. In contrast, a heat engine is less suitable for supplying only one printing machine or only one corrugating machine, since their respective power demand ratios (ratio of thermal power to electrical power demand) do not specifically correspond to the power ratio of the heat engine.

[0007] The method according to the invention is used to operate an apparatus. The apparatus comprises a corrugated board machine for producing corrugated board. For example, the corrugated board is produced as a continuous corrugated board web or as an assembly batch. In addition, the apparatus has a printing device for printing a paper layer with a printed product, in particular by means of a printing head. The printing device and the corrugated board machine are in particular operated simultaneously. The paper layer is preferably used for producing corrugated board and is transferred from the printing device to the corrugated board machine for this purpose, but this is not mandatory in itself. The printing is preferably carried out even before the paper layer is further processed, in particular before it is connected to other paper layers to form the corrugated board. Alternatively, the paper layer is printed if it is already connected to one or more other paper layers. The printing device is preferably a digital printing device, although other printing devices are also suitable in principle, but this is assumed in the following without limiting the generality.

[0008] In general, in an advantageous embodiment, the plant is used for producing printed corrugated board. The printing plant and the corrugated board plant are preferably operated inline (inline operation), i.e. the printed paper layer passes through the printing plant and the corrugated board plant without being wound and unwound again in between. With regard to the control of the conveying speed, the printing plant preferably follows the corrugated board plant, i.e. the corrugated board plant specifies the conveying speed, which is then taken over by the printing plant. The conveying speed varies, in particular, depending on the current production order of the plant, so that the thermal power and electrical power requirements can also vary accordingly within a certain range.

[0009] As an alternative to the above-described inline operation, a design in which the printing plant and the corrugating board plant are operated separately from each other is also suitable, that is, the paper layers are not directly transferred to the corrugating board plant and, in one possible design, are even used elsewhere and are not further processed in the corrugating board plant. For example, the printing plant and the corrugated board web produce the printed paper layers on the one hand and the corrugated board on the other hand completely independently of each other. In a suitable design, the printing plant is operated in roll-to-roll mode, i.e. the paper layers are unrolled at the inlet of the printing plant, then printed by the printing plant and finally rolled up into a roll at the end of the printing plant. The roll is then transferred to the corrugating board plant and unrolled again there to produce corrugated board, or the roll is used in a completely different way, for example in another corrugating board plant. Alternatively or additionally, the corrugating board plant is similarly operated in roll-to-sheet mode. In each case, the respective conveying speeds of the printing plant and / or the corrugating board plant also vary regularly according to the current production order, so that the thermal power and electrical power requirements also vary accordingly within certain limits.

[0010] The device also includes a heat engine for generating thermal power and electrical power. The heat engine preferably includes a gas turbine and, in particular, also includes a generator. The gas turbine operates with gas as the primary energy carrier (i.e. a chemically supplied primary energy source) and, during its combustion, generates, on the one hand, mainly thermal power and, on the other hand, mechanical power, which drives a generator, which then generates electrical power. Without limiting the generality, a gas turbine with a generator is assumed below, but other heat engines are also suitable in principle. Preferably, the entire device uses only one single primary energy source with a CO2 balance that is as low as possible (e.g. SNG, biogas or green hydrogen).

[0011] The corrugating machine and the printing machine now form a component, so that the heat power and the electrical power are jointly provided by the heat engine, i.e. the heat power and the electrical power generated by the heat engine are distributed between the corrugating machine and the printing machine. In this case, both the corrugating machine and the printing machine consume heat power and electrical power in particular. As mentioned above, it is not important whether the printing machine and the corrugating machine are operated inline or separately from each other. First of all, it is only important that the heat power and the electrical power are jointly provided by the heat engine to the combination of the printing machine and the corrugating machine.

[0012] A significant advantage of the invention is that the power demand ratio of the combination of a corrugating machine and a printing machine corresponds particularly well to the power ratio of a heat engine. When the printing machine and the corrugating machine are operated simultaneously, their thermal and electrical power requirements are added and can then be operated jointly by a single heat engine as described above. By combining the corrugating machine with the printing machine, the disadvantages of the combined heat and power or combined heat and power process, which can only be used with difficulty when considered separately, are advantageously eliminated. Thus, it has been observed that, for example, a gas turbine has a power ratio of approximately 2:1 (e.g. 3.7 MW of thermal power and 1.8 MW of electrical power), while a corrugating machine generally has a power ratio of approximately 10:1 (e.g. 2.5 MW of thermal power and 250 kW of electrical power), and a printing machine has a power ratio of approximately 1:1 (e.g. 1 MW of thermal power and 1 MW of electrical power each). However, the combination results in a power demand ratio of approximately 2.8:1, so that in the combination of a corrugating machine and a printing machine, the use of a combined heat and power or combined heat and power process is particularly economical. Heat engines therefore have a corresponding ratio of thermal power to electrical power that allows for minor deviations from the ideal ratio, in particular when excess electrical power is generated, since this can be transferred particularly easily into the grid. Heat engines with a power ratio of 2:1 to 3:1 (heat to electricity) are therefore already advantageous. As explained in more detail below, the power requirement ratio for the composite material can still be adjusted within certain limits, so that the power ratio of the heat engine can be further optimized and approached. Since the CHP / CHP process enables maximum utilization of chemical primary energy, efficiency is significantly increased compared to the separate operation of the corrugating plant and printing plant. In addition, operating costs during network operation are reduced. As long as CO2-neutral primary energy carriers are used, the CO2 load in corrugated board manufacturing is correspondingly reduced.

[0013] In order to operate the plant as economically as possible, it is designed in particular in such a way that in each case there are as many simultaneous consumers as possible for the thermal power and electrical power of the heat engine (demand simultaneity factor). This is particularly desirable in the combination of a corrugated board plant and a printing plant described here, thus providing not only an economical but also a possible CO2-neutral method of energy supply. But even when fossil gas is used in the heat engine, CO2 emissions corresponding to the power are significantly reduced.

[0014] The heat engine preferably provides thermal power in the form of hot gas, wherein a first hot gas portion is used in the printing plant, in particular directly for drying the paper layers and / or printed products, and a second hot gas portion is used to generate process steam for the corrugated board plant. In the case of a gas turbine, the hot gas is the flue gas generated during the combustion of the primary energy carrier. The temperature of this flue gas is in particular in the range of 500° C. to 600° C. The thermal power of the heat engine is therefore utilized in two different ways, i.e. the plant is in this respect a bivalent system: on the one hand, the hot gas in the printing plant is used directly for drying (direct thermal utilization) and, on the other hand, for simultaneously generating process steam for the corrugated board plant (indirect thermal utilization). Downstream of the heat engine, the hot gas flow is divided into two partial flows, one of which is directed to the printing plant and the other to a waste heat boiler, with which process steam for the corrugated board plant is generated, in particular by means of sensible heat in the waste heat boiler.

[0015] The first hot gas portion is preferably at least partially supplied to a predryer of the printing apparatus for drying the paper layer before printing, in particular in order to pretreat the paper web to obtain a more stable process. Alternatively or additionally, the first hot gas portion is at least partially supplied to a hot air dryer of the printing apparatus for drying the printed product, i.e. for drying after printing. Predryers and hot air dryers are also often referred to as dryers. In each case, the dryer is preferably configured as a convection dryer, i.e. it discharges hot drying air which is in direct contact with the paper layer and, if necessary, with the printed product (direct gas drying). Hot air from a heat machine is particularly suitable for such direct hot convection drying in a printing apparatus, since the hot air does not contain particles or similar contaminants in principle. In addition, the hot air is sterile and contains essentially CO2, N2 and water vapor. In such direct gas drying, a heat exchanger which would generate heat transfer losses is advantageously not required and is appropriately omitted. Another advantage of using gas directly is that, for reasons of energy efficiency, internal recirculation air operation can be omitted and is also conveniently omitted. In the recirculating air, the water vapor partial pressure and the relative humidity will increase, with the result that the drying / evaporation of the solvent under pressure will in principle be suppressed. The recirculating air operation of the dryer dispenses with complex ductwork and radial fans for supply and recirculating air. In addition, the drying air has an almost constant moisture load, which has a positive effect on the drying characteristics of the printed product.

[0016] The printing in the printing device is preferably based on an inkjet process. Preferably, the printing device uses only one or more water-based inks to print the paper layer. This avoids flammable solvent mixtures combined with hot gases, which helps to prevent explosions.

[0017] The temperature of the specific drying air in the specific dryer, i.e. the drying temperature, is in particular adjustable and conveniently adjustable in the range of 100° C. to 600° C. as required. The drying temperature is preferably adjusted by mixing in fresh air. In a preferred design, the drying temperature in the hot air dryer is controlled or even adjusted as a function of the transport speed of the paper layer through the printing device. This is based on the consideration that when the transport speed changes, the time for which the paper layer and the printed product are in contact with the drying air also changes. In order to obtain a consistent drying result, the drying temperature is then appropriately adjusted, i.e. the drying temperature is reduced at lower transport speeds and, vice versa, the drying temperature is increased at higher transport speeds.

[0018] In a suitable embodiment, the exhaust gas stream from the hot air dryer is supplied to a predryer for drying the paper layer before printing. The drying air is directed onto the paper layer in the hot air dryer and then discharged as an exhaust gas stream. Since the drying air may not release all of its heat to the paper layer under the print, the exhaust gas stream has a corresponding waste heat (e.g., a temperature in the range of 100° C. to 200° C.), which is now still used in the predryer. Alternatively or additionally, depending on the temperature of the hot air dryer, the exhaust gas stream of the hot air dryer is advantageously used at high temperature, in particular in the range of 200° C. to 400° C., and / or used in an exhaust gas recovery device (in particular an air / air recovery device) at low temperature, in particular in the range of 100° C. to 200° C., for producing a process refrigerant, for example in an absorption chiller. The same applies to the corresponding exhaust gas stream of the predryer, if present.

[0019] In addition to the first hot gas portion for direct gas utilization, the second hot gas portion is supplied to the waste heat boiler (also called partial flow waste heat boiler) in particular via a regulated hot gas bypass, which is, for example, configured with a valve for dividing the hot gas into two hot gas portions (with which the direct gas utilization is then "bypassed" and the hot gas is supplied to the waste heat boiler and vice versa). The distribution of the hot gas between the two hot gas portions, i.e. the ratio of the first hot gas portion to the second hot gas portion, is conveniently regulated, in particular via the hot gas bypass. In this case, appropriate regulation is carried out depending on the medium with the highest added value. This is in particular process steam. When the plant is started up, it is convenient to measure the maximum volume flow of the hot gas (first hot gas portion) that must be branched off in order to use the gas directly for drying in the printing plant. The remaining hot gas is fed to the waste heat boiler (second hot gas portion). This design is part of the process balance. The heat engine is then designed accordingly depending on the power ratio. If the respective thermal power requirements of the corrugated board machine and the printing machine vary, the distribution of the hot gas between the first and second hot gas portions is preferably controlled so that the corrugated board machine is in particular always supplied with sufficient thermal power and thus has priority over the thermal power supply to the printing machine. In other words, the thermal power requirement of the corrugated board machine has priority over the thermal power requirement of the printing machine. A possible shortage of thermal power supplied to the printing machine is appropriately compensated by providing additional thermal power generated separately from the thermal power of the heat machine, in particular by heating elements, such as gas burners or electric heating registers, etc. The latter has the advantage of conveniently using the electrical power of the heat machine, which may be slightly in excess in any case. As a result, the demand of the corrugated board machine for process steam has overall priority, i.e., if more power is suddenly needed to generate process steam, the first hot gas portion is correspondingly reduced compared to the second hot gas portion, i.e., less hot gas is conveyed to the printing machine for drying. As described above, the reduction of the first hot gas portion is appropriately compensated by the additional thermal power.

[0020] In principle, it is advantageous to supply the hot air for direct air drying to one or more dryers in continuous operation and to discharge it again from there as exhaust air, and if necessary, to use any waste heat elsewhere. However, a variant is also advantageous in which one or more dryers of the printing system are operated at least temporarily or even permanently in recirculation air mode, i.e. the supplied hot air is not only simply passed through and then discharged as exhaust air, but is at least partially circulated continuously. As mentioned above, recirculation air operation is particularly advantageous if the lack of thermal power of the printing device is compensated by providing additional thermal power with heating elements (e.g. gas burners, electric heating registers, etc.). Therefore, by recirculation air operation, the supply of hot air flow is advantageously reduced, since the temperature of the recirculation air cooled by heat losses only needs to be kept constant. In general, at least the following two variants are advantageous. In a first variant, the drying is carried out in continuous operation. Compared to recirculation air operation, the required hot air flow here is higher, but the required temperature is lower, since the volume flow must be relatively large in order to achieve a specific, required blow-off velocity at the dryer outlet (e.g. dryer nozzle) (in recirculation air operation, this is achieved by a separate recirculation air fan). In the second variant, partial recirculation air operation (mixed operation) takes place. Compared to continuous operation, the required hot air flow is now much lower, but the temperature must be higher in order to compensate for the heat losses of recirculation air operation. In particular, the heating element is used only to compensate in the event of the above-mentioned deficiency and then represents a backup solution in this respect in order to compensate any peaks in the thermal power demand as required.

[0021] However, in an advantageous design, the recirculation air operation can alternatively or additionally be used in a different way, as follows: Since the hot air from the heat engine usually has a temperature that is much higher than the temperature required for drying, this hot air can also be used in the recirculation air operation for a period of time or even permanently before the temperature drops below the minimum temperature required for drying. Therefore, in an advantageous design, at least a part of the hot air from the heat engine is supplied to the hot air dryer of the printing device (preferably the above-mentioned hot air dryer), which is then operated in the recirculation air mode. The minimum temperature is in particular at least the temperature required for drying, and is preferably in the range of 200° C. and 300° C. In contrast, the hot air from the heat engine has a significantly higher temperature, preferably in the range of 500° C. to 600° C., or 200° C. to 400° C. above the minimum temperature, so that a correspondingly large amount of heat is generated for the recirculation air operation. When the hot air temperature in the hot air dryer reaches the minimum temperature, the hot air, which can now be said to be "used", is discharged as exhaust air and the process is restarted as required.

[0022] A suitable recirculation air operation is partial recirculation air operation (also called mixed operation), in which only a part of the hot air circulates in the hot air dryer and another part is discharged as exhaust air and then conveniently replaced by fresh hot air. 100% (completely closed) recirculation air operation is usually not possible, since solvents (mainly water vapor) would be concentrated in the recirculation air. Therefore, even in recirculation air operation, it is convenient to supply cold, uncontaminated fresh air and discharge contaminated, hot exhaust air, but both volume flows are kept as small as possible. Preferably, if there is too little hot air for drying in the printing plant, a switch is made to partial recirculation air operation. In this operation, additional heating elements, such as gas burners or the like, can also be used in the recirculation air and are preferably also used, which is not possible in the case of direct continuous drying.

[0023] The waste heat boiler generates in particular saturated steam, for example at 16 bar, and thus advantageously covers the entire process steam requirement and thus also the entire thermal power requirement of the corrugated board plant. The second part of the divalent heat utilization significantly increases the overall efficiency of the plant.

[0024] The process steam for the corrugated board plant is appropriately first conveyed from the waste heat boiler to a steam distributor, which then conveys the process steam at an appropriate pressure to the corresponding treatment stations of the corrugated board plant. The corrugated board plant has in particular one or more of the following treatment stations: a preheater for preheating one or more paper layers, e.g. before gluing; a laminating unit and / or a heating and stretching section, each for gluing a plurality of paper layers together; a modular facing machine for the corrugated paper layers (e.g. with slotting rollers). One or more of the above-mentioned treatment stations has a heating device and / or a humidifying device, e.g. a heating plate or a spray beam, which requires process steam.

[0025] As already pointed out at the beginning, the thermal power requirement of the composite material may vary depending on the current production order. Therefore, the plant appropriately has a steam storage device, by means of which the thermal power requirement of the composite material that varies over time is compensated. In other words: in particular, the heat engine generates in each case a substantially constant amount of thermal power and electrical power, whereas the composite material can have different thermal power and electrical power requirements depending on the production application. Any excess thermal power is then transferred to the steam storage device or, conversely, removed from this thermal power if the thermal power requirement of the composite material exceeds the thermal power of the heat engine (with regard to electrical power, analogously, for example, a public network is used instead of a steam storage device). The hot gas from the heat engine (more precisely: the hot gas from the second hot gas flow) is stored in the steam storage device and used, if required, for the printing plant or the corrugated board plant or both. In an advantageous embodiment, hot water or hot steam is separated from the waste heat boiler or the steam storage device, if required, and used to produce a process refrigerant. In an advantageous embodiment, the hot steam is used as saturated steam for re-moistening and / or for adjusting the transverse wetting profile in the printing plant.

[0026] In a suitable design, the ratio of the thermal power of the first and second hot gas parts is 3:4 to 1:4, that is, most of the thermal power is supplied to the waste heat boiler and / or steam storage, and is used as process steam for the corrugated board equipment, while only about 20% to 45% of the thermal power is used for the printing equipment. For example, the thermal power of direct use of gas (first hot gas flow) is 1.6 MW, and the remaining thermal power (second hot gas flow) is 2.5 MW, with a ratio of about 2:3.

[0027] In an advantageous embodiment, the device is designed to generate a process refrigerant and, for this purpose, has in particular an absorption refrigeration machine and / or a compression refrigeration machine. The process refrigerant is advantageously used to cool one or more components of a printing plant and / or a corrugated board plant, for example, to operate a cooling roller for cooling a paper layer in a printing plant. The process refrigerant is supplied, for example, via cooling water which is cooled by the absorption refrigeration machine and / or the compression refrigeration machine.

[0028] The absorption refrigeration machine is operated with thermal power, for example, as described above, with the exhaust gas flow from the printing device, or with hot water or hot steam from a waste heat boiler or a steam storage, or directly with hot gas from a heat engine. On the other hand, the compression refrigeration machine is operated by electrical power, which in particular comes directly from the heat engine. Therefore, depending on the supply of thermal power and electrical power, the process refrigerant can be produced flexibly in different ways. Therefore, in an advantageous design for producing the process refrigerant, the device has an absorption refrigeration machine operated with thermal power and a compression refrigeration machine operated with electrical power, and the respective power consumption of the absorption refrigeration machine and the compression refrigeration machine is controlled in such a way that the combined thermal power demand and the electrical power demand are adapted as best as possible to the electrical power and the thermal power of the heat engine. In other words, in each case, a given amount of process refrigerant is produced by the absorption refrigeration machine and the compression refrigeration machine in proportion, so that the thermal power and the electrical power of the heat engine are optimally utilized. Therefore, the power consumption of the absorption refrigeration machine and the compression refrigeration machine is controlled according to the type of power still available at a given time, so that the combined power demand ratio is optimized as a whole. This is based on the consideration that the way in which the process refrigerant is generated is independent of the use of the process refrigerant. For example, if no thermal power is available at a given time to generate the process refrigerant, but electrical power is, the process refrigerant is generated with a compression refrigerator. Conversely, in the case of an excess supply of thermal power, the process refrigerant is generated by an absorption refrigerator. The generated process refrigerant is preferably kept constant. Mixed operation is also possible and is advantageous depending on the respective power provision.

[0029] As long as a sufficient amount of thermal power is available, the absorption chiller is preferably operated as a continuous chiller, which is designed for the longest possible number of operating hours. The compression chiller is preferably only activated to cover the peak cooling load and otherwise remains inactive. The compression chiller is thus an emergency unit that is only activated in exceptional cases to operate the peak load, while the absorption chiller in particular always operates the base load.

[0030] Like the thermal power, the electrical power of the heat machine is also used by the printing plant and the corrugated board machine. In a preferred embodiment, the electrical power is used to operate at least one infrared dryer (i.e., infrared dryer) of the printing plant, at least one drive (i.e., for conveying one or more paper layers, corrugated board or an intermediate product thereof) of the printing plant and / or the corrugated board machine and at least one processing station, such as the wet end or dry end of the corrugated board machine. The dry end preferably has one or more of the following processing stations: transverse cutter, longitudinal cutter, slitting device, slotting device. The dry end is adjacent to the wet end of the corrugated board machine and refers to that part of the corrugated board machine to which the paper layers connected together to form the corrugated board web are supplied for further processing, in particular assembly, i.e. the paper layers are no longer present separately at the dry end, but are connected to the corrugated board web.

[0031] Infrared dryers in printing devices are used in particular for drying printed products. Compared with convection drying, the advantage of infrared dryers is that they do not particularly blur the still fresh printed image. Therefore, the infrared dryer is preferably arranged directly downstream of the print head of the printing device. However, the disadvantages of infrared dryers are their high electrical power demand (usually in the range of about 500 kW to 1000 kW), their relatively short life (for example, the limited life of the carbon filament) and the fact that the effectiveness of drying depends on the absorption coefficient of the printing ink and therefore sometimes on the color. In order to eliminate the above-mentioned disadvantages of infrared dryers and to integrate an additional heat sink into the device, it is advantageous to combine the infrared dryer with a hot air dryer in the printing device. Instead of using the infrared dryer exclusively for drying, it is smaller in size and combined with the hot air dryer so that at least the required drying performance is achieved in total. Therefore, in an advantageous design, the printing device has at least one infrared dryer and at least one hot air dryer (in particular as described above) for drying the printed products, and the infrared dryer is arranged upstream of the hot air dryer with respect to the conveying direction of the printed paper layer. In this way, the printed product is pre-dried by the infrared dryer before the necessary remaining drying is carried out by the hot air dryer. By pre-drying with the infrared dryer, blurring of the printed product during drying in the hot air dryer is advantageously avoided. In addition, the hot air dryer reduces the demand for electrical power of the printing equipment and has lower maintenance costs compared to the infrared dryer.

[0032] Preferably, the printing device has at least two infrared dryers, namely a first infrared dryer located upstream of the hot air dryer and a second infrared dryer located downstream of the hot air dryer (with respect to the transport direction of the paper layer).

[0033] Similar to the combination of absorption refrigeration machine and compression refrigeration machine for producing process refrigerant, the combination of infrared dryer and dryer is also advantageously able to optimize the power demand ratio of the composite material, so that the heat and electric power demand can be adapted to the actual available heat and electric power, if necessary, also in response to the changed operation, for example, by changing the production order of the equipment. The above statements about the production of process refrigerant are also applicable to drying, and vice versa. In an advantageous design, the printing device for drying printed products has an infrared dryer operated with electric power and a dryer (hot air dryer) operated with thermal power. The infrared dryer and dryer preferably correspond to the above-mentioned infrared dryer or hot air dryer, respectively. The respective power consumption of the infrared dryer and the dryer is now controlled in such a way that the thermal power demand and the electric power demand of the components are adapted to the electric power and the thermal power of the heat machine. For example, in the case of an oversupply of thermal power, the power demand of the dryer increases and the power demand of the infrared dryer decreases (correspondingly, in the case of an oversupply of electric power, the opposite), appropriately in a way that the drying power of the dryer and the combination of infrared dryers remains constant. Similar to the combination of an absorption chiller and a compression chiller, one dryer, especially a hot air dryer, operates with respect to the base load of drying, while the other dryer, especially an infrared dryer, operates with peak load only when needed. However, in detail, the control of the different dryers depends on the design of the entire plant (number, type and performance of the different dryers) and the process balance (thermal and electrical power distribution between the corrugated board plant and the printing plant).

[0034] For the purpose of illustration, a preferred embodiment of the device is described in summary below. A paper layer is fed to a printing device, for example starting from an unwinder. The paper layer is first optionally predried with a predryer. The paper layer is then printed with a plurality of printing heads, i.e. a print is provided, which is then dried first with an infrared dryer and then with a hot air dryer. Optionally, a further infrared dryer follows as a booster, in order to achieve a particularly high drying performance in total, for example at particularly high conveying speeds, if necessary. The printed and dried paper layer is finally cooled by one or more cooling rollers and then transferred, in particular, directly to a corrugated board machine. Therein, the paper layer is bonded to other paper layers at the wet end to form a corrugated board web and then optionally assembled at the dry end. The finished corrugated board is then output from the corrugated board machine as a continuous product or as several batches. The thermal power of the heat machine is distributed on the one hand to the predryer and the hot air dryer and on the other hand to the waste heat boiler and the optional steam storage. The waste heat boiler supplies process steam to the individual processing stations of the corrugated board machine for joining the paper layers to form corrugated boards. Optionally, part of the thermal power of the printing plant and / or one or more exhaust gas streams is used to produce process refrigerant and / or is supplied to an exhaust gas recovery unit for preheating fresh air for the heat engine. The cooled but still warm exhaust gas from the exhaust gas recovery unit is used, for example, to produce process refrigerant. The electrical power of the heat engine is distributed to the infrared dryer of the printing plant and to one or more drive units of the printing plant and the corrugated board plant. In addition, electrical power is supplied to the dry end for the assembly of the corrugated board web there, for example for cutting and / or slotting. If necessary, the excess electrical power is fed into the public grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In the following, embodiments of the present invention are explained in more detail with reference to the accompanying drawings, wherein:

[0036] Figure 1 shows a flow chart for operating the device,

[0037] Figure 2 Shows Figure 1 Process balance of equipment. DETAILED DESCRIPTION

[0038] Figure 1The device 2 shown has a corrugated board machine 4 for producing corrugated board 6, which is produced, for example, as a continuous corrugated board web or as an assembly batch. In addition, the device 2 has a printing device 8, here a digital printing device, which has a plurality of printing heads (not explicitly shown) for printing a paper layer 10 with a printed product. In the embodiment shown here, an in-line operation is realized, wherein the printed paper layer 10 is transferred directly from the printing device 8 to the corrugated board machine 4 in order to use the paper layer 10 in the production of the corrugated board 6. On the other hand, in an alternative embodiment not explicitly shown, the printing device 8 and the corrugated board machine 4 are operated separately from each other, and the printing device 8 is operated, for example, in a roll-to-roll operation. Regardless of whether the printing device 8 and the corrugated board machine 4 are operated in-line or separately, they are operated simultaneously in any case.

[0039] In the embodiment shown, printing is performed even before the paper layer 10 is connected with other paper layers to form the corrugated board 6. Therefore, the device 2 is generally used for the production of printed corrugated board 6. The printing device 8 and the corrugated board machine 4 operate in-line, i.e. the printed paper layer 10 passes through the printing device 8 and the corrugated board machine 4 without being wound and unwound again in between. If the paper layer 10 is not used for the production of corrugated board 6 together with the corrugated board machine 4, the device 2 is in any case used for the production of printed paper layers 10 on the one hand and for the production of corrugated board 6 on the other hand.

[0040] The device 2 also includes a heat engine 12 for generating thermal power Pth and electrical power Pel from the supplied chemical power Pchem. In the embodiment shown, the heat engine 12 has a gas turbine, not explicitly shown, and a generator, also not explicitly shown. The gas turbine operates with gas as primary energy source 14.

[0041] The corrugated board machine 4 and the printing machine 8 now form a composite structure, so the thermal power Pth and the electrical power Pel are jointly provided by the heat engine 12, that is, the thermal power and the electrical power Pth, Pel generated by the heat engine 12 are distributed to the corrugated board machine 4 and the printing machine 8, which consume thermal power and electrical power respectively. Figure 2 A possible process balance for allocating thermal and electrical powers Pth, Pe1 is shown. Figure 2 In the embodiment of the invention, the electric power Pel is 1.9 MW and the thermal power Pth is 4.1 MW, so that the power ratio of the heat engine 12 is about 2:1. The thermal power Pth is then distributed again to the printing device 8 and the corrugated board device 4 in a ratio of 2:3, with the corrugated board device 4 receiving a larger proportion. However, the values ​​and ratios may be different depending on the specific design of the entire device 2.

[0042] The heat engine 12 shown here provides a thermal power Pth in the form of hot gas at, for example, 550° C., wherein a first hot gas portion 16 is used directly in the printing unit 8 for drying the paper layer 10 and / or the printed product. A second hot gas portion 18 of the hot gas is used to generate process steam 20 for the corrugated board plant 4. The thermal power Pth is used in two different ways, namely on the one hand for drying in the printing unit 8 (direct heat utilization) and on the other hand for simultaneously generating process steam for the corrugated board plant 4 (indirect heat utilization). Downstream of the heat engine 12, the hot gas flow is divided into two partial flows 16, 18 via a hot gas bypass 21 (here realized by a valve), one of which is led to the printing unit 8 and the other to a waste heat boiler 22, which is used to generate process steam 20 for the corrugated board plant 4.

[0043] The first hot air portion 16 is partially supplied to a pre-dryer 24 for drying the paper layer 10 before printing. Figure 1 In the embodiment shown, the first hot air portion 16 is also partially supplied to a hot air dryer 26 for drying the printed products, i.e. for drying after printing. The predryer 24 and the hot air dryer 26 are also often referred to as dryers. The dryers 24, 26 are each configured as convection dryers, that is to say they discharge hot drying air which comes into direct contact with the paper layer 10 and, if necessary, with the printed products (direct gas drying). The temperature of the respective drying air in the respective dryer 24, 26, i.e. the drying temperature, is adjustable and, in the illustrated embodiment, is adjusted as required in the range of 100° C. to 600° C., in this case by mixing in fresh air 28 having a temperature of, for example, 20° C.

[0044] The following calculation example is intended to roughly illustrate the design of the device 2: The heat engine 12 provides hot gas with a mass flow rate in the range of 5 to 10 kg / s, such as Figure 2 As shown, the hot air is distributed to the printing machine 8 and the corrugated board machine 4 in a ratio of approximately 2:3. Knowing the temperature of the hot air, the corresponding volume flow can be calculated and distributed to the various tasks, in particular the dryers 24, 26. The volume flow of the printing machine 8 and its temperature are regulated by the fresh air 28, the flow of which is determined according to the specific requirements. For example, about half of the hot air temperature is selected as the temperature of the dryers 24, 26, for which the first hot air portion 16 is mixed with the fresh air 28 in a ratio of approximately 3:1 (volume flow ratio) in order to obtain a sufficient amount of hot air with a sufficient temperature for drying.

[0045] In addition, Figure 1In the embodiment of the present invention, the waste gas stream 30 from the hot air dryer 26 is supplied to the predryer 24 for drying the paper layer 10 before printing. The drying air is directed onto the paper layer in the hot air dryer and then discharged as the waste gas stream 30. Alternatively or additionally, in a design not shown, the waste gas stream 30 is used in a waste gas recovery device and / or for generating a process refrigerant 44, depending on its temperature. The same applies to the corresponding waste gas stream of the predryer 24, if present.

[0046] In addition to the first hot gas portion 16 for direct gas utilization, in this case a second hot gas portion 18 is supplied to a waste heat boiler 22. This produces saturated steam, thereby meeting the entire process steam demand of the corrugator 4. The process steam 20 for the corrugator 4 is firstly conducted from the waste heat boiler 22 to a steam distributor 32, which then conducts the process steam 20 at an appropriate pressure to the corresponding processing stations of the corrugator 4. The corrugator 4 shown here as an example has the following processing stations: a preheater 34 for preheating one or more paper layers; a modular facing machine 36 for corrugating paper layers; a laminating unit 38 and a heating and stretching section 40, each for bonding a plurality of paper layers together.

[0047] Depending on the current production order, the thermal power requirements of the composite material may change. Figure 1 The device 2 in the embodiment further has a steam accumulator 42, with which the time-varying thermal power requirement of the composite material is compensated. The hot gas is stored in the steam accumulator 42 and can be withdrawn when required. In the embodiment shown here, hot water or hot steam can even be separated from the waste heat boiler 22 or the steam accumulator 42 if necessary and used to produce a process refrigerant 44. In an advantageous embodiment, the hot steam is used as saturated steam for re-moistening and / or for regulating the transverse moistening profile in the printing device.

[0048] As already indicated, the plant 2 shown here is designed to produce a process refrigerant 44 and, for this purpose, has in this example an absorption refrigeration machine 46 and a compression refrigeration machine 48. The process refrigerant 44 is used to cool one or more components of the printing plant 8 and / or the corrugated board plant 4. Figure 1 In particular, it is used to operate a cooling roller 50 to cool the paper layer 10 in the printing device 8. The process refrigerant 44 is supplied, for example, by cooling water 52, which is cooled by an absorption refrigerator 46 and a compression refrigerator 48.

[0049] The absorption chiller 46 is operated with a thermal power Pth, while the compression chiller 48 is operated with an electrical power Pel. Thus, depending on the supply of thermal and electrical powers Pth, Pel, the process refrigerant 44 can be produced flexibly in different ways. Thus, in this example, the respective power consumptions of the absorption chiller 46 and the compression chiller 48 are controlled in such a way that the thermal power demand and the electrical power demand of the components are adapted as best as possible to the electrical power Pel and the thermal power Pth of the heat engine 12. Thus, the power consumptions of the absorption chiller 46 and the compression chiller 48 are controlled depending on the type of power Pth, Pel available at a given time, so that the power demand ratio of the combination is optimized as a whole.

[0050] Like the thermal power Pth, the electrical power Pel is also used by the printing device 8 and the corrugated board machine 4. In the embodiment shown, the electrical power Pel is used to operate the two infrared dryers 54, 56 (i.e., infrared dryers) of the printing device 8, as well as the corresponding drives 62 of the printing device 8 and the corrugated board machine 4, and is also used to operate at least one processing station of the dry end 58 of the corrugated board machine 4. The dry end 58 has one or more of the following processing stations: transverse cutter, longitudinal cutter, slitting device, slotting device. For the sake of simplicity, these are not explicitly shown here. The dry end 58 is connected to the wet end 60 of the corrugated board machine 4.

[0051] The infrared dryer 54 is arranged directly downstream of the printing head of the printing device 8. In the printing device 8, it is combined with the hot air dryer 26 as an additional heat sink. Figure 1 As shown, the infrared dryer 54 is arranged upstream of the hot air dryer 26 with respect to the conveying direction of the printed paper layer 10. In this way, the printed product is pre-dried by the infrared dryer 54 before the remaining drying by the hot air dryer 26. In addition, the printing device 8 shown here also includes a second infrared dryer 56 located downstream of the hot air dryer 26.

[0052] Similar to the combination of the absorption refrigeration machine 46 and the compression refrigeration machine 48 for producing the process refrigerant 44, the combination of the infrared dryers 54, 56 and the dryers 24, 26 also makes it possible to optimize the power demand ratio of the composite material, so that the thermal power and electrical power demand are adapted to the actually available thermal power and electrical power Pth, Pel. The statements about the production of the process refrigerant 44 also apply to the drying, and vice versa. The respective power consumption of the infrared dryers 54, 56 and the dryers 24, 26 is now controlled in such a way that the thermal power demand and electrical power demand of the components are adapted to the electrical power Pel and thermal power Pth of the heat engine 12.

[0053] If necessary, excess electric power Pel is fed into the public network 64 .

[0054] Reference numerals list

[0055]

Claims

1. A method for operating a device (2), - wherein the device (2) comprises a corrugated board device (4) for producing corrugated board (6), -in, The device (2) has a printing device (8) for printing a paper layer (10) with a printed product. - wherein the device (2) has a heat engine (12) for generating thermal power (Pth) and electrical power (Pel), - wherein the corrugated board device (4) and the printing device (8) form a composite material, so that the thermal power (Pth) and the electrical power (Pel) are jointly provided by the heat engine (12).

2. The method according to claim 1, in, The heat engine (12) provides the thermal power (Pth) in the form of hot air, wherein a first hot air portion (16) is used for drying in the printing device (8) and a second hot air portion (18) is used to generate process steam (20) for the corrugated board device (4).

3. The method according to claim 2, in, When the respective thermal power requirements of the corrugated board machine (4) and the printing machine (8) fluctuate, the distribution of the hot air between the first hot air portion and the second hot air portion (16, 18) is adjusted in such a way that sufficient thermal power (Pth) is supplied to the corrugated board machine (4) so ​​as to have priority over the thermal power (Pth) supplied to the printing machine (8), Therein, a possible shortage of thermal power supplied to the printing device (8) is compensated by providing additional thermal power generated separately from the thermal power (Pth) of the thermal engine (12).

4. The method according to claim 2 or 3, in, The first hot air portion (16) is at least partially supplied to a pre-dryer (24) of the printing device (8) for drying the paper layer (10) before printing.

5. The method according to any one of claims 2 to 4, in, The first hot air portion (16) is at least partially supplied to a hot air dryer (26) of the printing device (8) for drying the printed product.

6. The method according to claim 4 and claim 5, in, The exhaust gas stream (30) from the hot air dryer (26) is supplied to the pre-dryer (24).

7. The method according to claim 5, in, The drying temperature in the hot air dryer (26) is controlled according to the conveying speed of the paper layer (10) through the printing device (8).

8. The method according to any one of claims 1 to 7, in, At least part of the hot air of the heat engine (12) is supplied to a hot air dryer (26) of the printing device (8), which then operates in circulating air mode.

9. The method according to any one of claims 1 to 8, in, The device (2) has a steam accumulator (42) which is used to compensate for the time-varying thermal power requirement of the composite material.

10. The method according to any one of claims 1 to 9, in, The device for producing a process refrigerant (44) has an absorption refrigeration machine (46) operated with a thermal power (Pth) and a compression refrigeration machine (48) operated with an electrical power (Pel), The respective power consumption of the absorption refrigerator (46) and the compression refrigerator (48) is controlled in such a way that the thermal power demand and the electrical power demand of the composite material match the electrical power (Pel) and the thermal power (Pth) of the heat engine (12).

11. The method according to any one of claims 1 to 10, in, The electrical power (Pel) used to operate - at least one infrared dryer (54, 56) of the printing device (8), - at least one drive of the printing device (8) and / or the corrugated board device (4), and - at least one processing station of the corrugated board machine (4).

12. The method according to any one of claims 1 to 11, in, The printing device (8) comprises at least one infrared dryer (54) and at least one hot air dryer (26) for drying the printed product. The infrared dryer (54) is arranged upstream of the hot air dryer (26) relative to the conveying direction of the paper layer (10).

13. The method according to any one of claims 1 to 12, in, The printing device (8) for drying the printed product comprises an infrared dryer (54, 56) operated with electric power (Pel) and a dryer (24, 26) operated with thermal power (Pth), The respective power consumption of the infrared dryer (54, 56) and the dryer (24, 26) is controlled in such a way that the thermal power demand and the electrical power demand of the composite material match the electrical power (Pel) and the thermal power (Pth) of the heat engine (12).

14. The method according to any one of claims 1 to 13, in, The heat engine (12) comprises a gas turbine.

15. The method according to any one of claims 1 to 14, in, The printing device (8) is a digital printing device.

16. The method according to any one of claims 1 to 15, in, The printing device (8) and the corrugated board device (4) operate online.

17. The method according to any one of claims 1 to 15, in, The printing device (8) and the corrugated board device (4) are operated separately from each other. Therein, the printing device (8) and / or the corrugated board device (4) are operated in particular in roll-to-roll operation and / or roll-to-sheet operation.

18. An apparatus (2) configured to operate according to the method of any one of claims 1 to 17.

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