Machine and method for the operation thereof for producing or treating a fibrous web, said machine having a heat pump

Abstract

The invention relates to a machine (1) and a method for producing or treating a fibrous web (F), in particular a paper, board or tissue web (F), comprising at least one machine section (2, 3, 4), preferably a dryer section (2, 4) or forming section (3), at least one thermal-energy load, preferably a steam and condensate system (5) and / or a secondary system load (70, 71, 82), and at least one thermal-energy recovery system (6), wherein a heat pump (90) extracts residual thermal energy from an exhaust-air flow of at least one exhaust-air line (84, 84') from at least one machine section (2, 3, 4) and, being additionally fed electrical energy (80), feeds thermal energy to the at least one thermal-energy load (5, 70, 71, 82), preferably to a condensate of the at least one condensate return line (58). According to the invention, the heat pump (90) is disposed in the exhaust-air line (84) such that the heat pump (90) recovers the residual thermal energy before a dew point temperature of the exhaust-air flow in the exhaust-air line (84, 84') is reached, and the steam and condensate system (5) comprises a steam accumulator (54) for storing the steam, said steam accumulator being downstream of the heat pump (90).

Description

[0001] Machine and method for its operation for the production or treatment of a fibrous web with a heat pump

[0002] The invention relates to a machine for producing or treating a fibrous web, in particular a paper, cardboard, or tissue web, comprising at least one machine section, preferably a drying section or forming section, and at least one thermal energy consumer, preferably a steam and condensate system and / or a secondary system consumer, and at least one thermal energy recovery system, and wherein the at least one machine section comprises at least one exhaust air line, and wherein the thermal energy recovery system is arranged in the at least one exhaust air line and comprises at least one heat pump, and wherein the at least one machine section and the at least one thermal energy consumer are operatively connected via the at least one thermal energy recovery system, such thatthat the heat pump partially extracts residual heat energy from an exhaust air flow of at least one exhaust air duct and supplies heat energy to a heating medium flow of one heat energy consumer with an additional supply of electrical energy.

[0003] The invention also relates to a method for use in a machine according to the invention.

[0004] The document DE102015219379 A1 discloses a machine and a method for operating a machine, wherein a medium for drying a fibrous web is supplied to a drying area and the medium is removed from the drying area downstream of the drying area and supplied as a heat source to a heat pump, by means of which a second medium is heated and supplied further downstream to a Yankee cylinder within the drying area.

[0005] The document DE102015219381 A1 discloses a machine and a method for operating a machine, wherein a medium for drying a fibrous web is supplied to a drying area and the medium is discharged from the drying area downstream of the drying area and supplied as a heat source to a heat pump, by means of which the same medium is heated with the addition of further energy and is supplied to the drying area at the beginning again.

[0006] Document W02020 079326 A1 discloses a heat pump insert into a recirculation system and a recirculation method for a drying section of a board or machine. The system comprises at least three air recirculation sections connected one after the other to a drying section hood in the running direction of a web-shaped material. Each recirculation section comprises one or more heat recovery units. Each heat recovery unit comprises a recirculation fan for sucking moist exhaust air from the drying section hood through the heat recovery unit and for supplying at least a portion of the conditioned moist exhaust air to the drying section hood, and an air-fluid heat exchanger for conditioning the moist exhaust air by cooling and reducing the moisture content of the moist exhaust air.

[0007] Document DE10 2007 051165 A1 discloses a machine and a method comprising a wet section and a dryer section, wherein the dryer section includes a drying section and a dryer section hood for the paper web. Energy from the exhaust air of the dryer section is fed via a heat pump to heat supply air in a heating device arranged in the wet section.

[0008] The document DE2630853 A1 , 1976, discloses a drying section for a machine, wherein a heat pump is connected between the inlet line with fresh, hot supply air and the outlet line with moist exhaust air, thereby enabling energy recovery from the exhaust air and transfer of the energy to the inlet line of the drying section.

[0009] Various drying devices are used to dry fibrous webs or tissue paper in the paper industry. These include, for example, contact drying sections and contactless drying sections. Contact drying sections include, for example, single-row and double-row drying cylinder drying sections, while contactless drying sections include, for example, air drying devices or infrared drying sections. Heat in the form of hot air for the drying sections is typically generated either by steam heating registers, preferably high-pressure steam heating registers, or gas burners. If steam is used, such as in steam-heated drying cylinders, it is often taken from a fossil-fuel-fired steam generator, for example, a combined cycle power plant.The hot air typically has an inlet temperature of greater than 180°C, sometimes even greater than 100°C, and can reach temperatures as high as 650°C. Steam air heaters, thermal oil air heaters, or gas burners are commonly used in the lower temperature range. Gas burners are predominantly used in the upper temperature range, and thermal oil air heaters are less common. The hot steam typically has temperatures greater than 110°C and less than 150°C.

[0010] However, the solutions mentioned to date have a number of disadvantages. The solutions mentioned in the prior art show the use of a heat pump within a drying section, sometimes in a recirculation mode, which is an unfavorable arrangement from an energy perspective. The medium for drying a fibrous web in a drying section requires a high level of thermal energy. Extracting further thermal energy from this medium after the initial cooling by the drying section using a heat pump and then increasing it again to supply a drying section or another system with electrical energy means increasing the thermal energy required at the beginning of the drying section and requiring more initial thermal energy to be supplied compared to direct recirculation.

[0011] The heat pump arrangements shown in a thermal energy recovery system for a drying section are significantly more efficient, as the thermal energy cannot actually be reused for the drying section, which operates at a higher temperature level. The recovery of thermal energy and supply of the dryer hood supply air heating are achieved through sometimes complex heat transfer systems. Another disadvantage is that the heat pumps are limited in providing the required increased energy levels from the perspective of an efficient operating point (COP). This results in a limited heating temperature by the heat pump if acceptable efficiency values ​​are to be achieved.

[0012] The machines also require a high level of fossil fuels, particularly natural gas, for drying the fibrous web, with the expected cost disadvantages. Rising procurement costs and increasingly stringent CO2 regulations and CO2 taxes account for a significant portion of manufacturing costs. Furthermore, due to global crises, availability and reputation with regard to the impact on the global climate are often other important considerations.

[0013] In the context of decarbonization, it would be ideal to use a heat pump to supply the dryer sections alone. However, this poses a number of challenges regarding the correct positioning of the heat pump in the machine and also for the operation of a paper machine. Normally, paper machines are operated around the clock for economic reasons, i.e. in a state of normal operation. However, unforeseen errors such as a web break or planned short downtimes can occur during normal operation, for example during a grade change or minor maintenance work. These short downtimes usually last from a few hours to a maximum of three days. The systems and machine sections do not usually cool down completely, but they do lose some heat energy, and when the machine is restarted, this is referred to as a warm start.During a warm start, the heat pump in use can only generate the larger temperature differences that then occur very inefficiently or not at all compared to normal operation. Further problems arise from the longer downtime that usually occurs every year for upcoming maintenance or a major overhaul of the machine. During this time, the machine cools down completely over several days or weeks, and the paper machine and its associated components must be completely warmed up from ambient temperature to operating temperature. A so-called cold start requires significantly more heat energy, which cannot be supplied by a heat pump alone.

[0014] The inventors have recognized that an advantageous arrangement in the machine and an optimized method of operation can eliminate the disadvantages.

[0015] The object of the invention is to provide a machine and a method for producing and / or treating a fibrous web, in particular a paper, cardboard or tissue web, with a heat pump, wherein the required heat energy for the drying section is provided in an energetically efficient manner mainly, preferably solely in normal operation, by an improved arrangement of a heat pump in the heat energy recovery system of an exhaust air.

[0016] A further object of the invention is to provide an efficient solution for the provision of heat energy in an exceptional operating case such as a cold start or a warm start for the operation of the machine with a sole provision of the required heat energy by a heat pump in normal operation.

[0017] A further object of the invention is to significantly reduce and / or completely eliminate the need for fossil fuels, especially natural gas, when drying a fibrous web. This significantly reduces operating costs, as well as the risk of dependence on a single consumption medium or supplier.

[0018] The object is achieved according to the invention by a machine and a method according to the independent claims. Further advantageous embodiments of the present invention can be found in the subclaims.

[0019] The machine according to the invention is characterized in that the at least one heat pump is arranged in the exhaust air duct in such a way that the heat pump recovers the remaining heat energy before the exhaust air flow in the exhaust air duct reaches a dew point temperature.

[0020] An arrangement of the heat pump before the dew point temperature of the exhaust air flow is reached means that at the inlet or the inlet temperature of the exhaust air flow into the heat pump, it is higher than the dew point temperature of the exhaust air flow. This enables the heat pump to reduce the temperature and residual heat energy of the available exhaust air to such an extent that the moisture absorbed by it during the drying process is at least partially, preferably completely, condensed in the heat pump. In other words, the exhaust air flow used is cooled below the dew point temperature as it flows through the heat pump. On the other hand, the heat extracted from the exhaust air flowing through the outlet line is transferred at a higher level into a heat consumer circuit, for example a steam and condensate system and / or a secondary system consumer. The heat energy required for the drying temperature can be completely electrically or.with non-fossil fuels and with lower energy consumption. By removing moisture from the exhaust air in the form of condensate, a significant saving in water consumption is achieved, for example, in the aforementioned case of a paper mill. At the same time, the environmental impact, which is often caused by the rising steam clouds caused by the moist exhaust air, is reduced.

[0021] The heat energy required for evaporation is advantageously obtained solely or at least partially from the exhaust air from various machine sections. This primarily includes the drying section with its various drying sections, which have the highest amounts of residual heat in the exhaust air. Large quantities of exhaust air from the vacuum blowers usually included in the drying sections or, for very large quantities, the vacuum blowers in the forming section can also be advantageously used. The exhaust air is recovered using a heat pump. The heat energy still contained in the exhaust air can be further recovered using multi-stage heat energy recovery systems, for example plate or tube bundle heat exchangers, and used to supply secondary system consumers, such as dryer hood supply air heating, process water heating, or heating water heating.The heat exchangers are arranged in the order of the temperature levels of the consumers to be supplied in order to keep the heating surfaces and costs of the heat exchangers as small as possible.

[0022] It is also advantageous if the steam and condensate system includes a steam storage unit downstream of the heat pump to store the steam.

[0023] Advantageously, the steam accumulator allows for the temporary storage of a sufficient amount of steam at a specific steam temperature. This temporary storage advantageously bridges periods during a warm start or possibly even a cold start of the machine, during which the heat pump will operate with limited or inefficient efficiency, or is unable to provide the required temperature level without the presence of residual exhaust air heat energy.

[0024] In an alternative embodiment, the machine is characterized in that at least one further heat exchanger is arranged upstream of the heat pump in the exhaust air line, preferably an air-air heat exchanger or an air-heat transfer medium heat exchanger.

[0025] In an alternative embodiment, the machine is characterized in that a further heat exchanger is arranged upstream of the heat pump in the exhaust air line, preferably an air-heat transfer medium heat exchanger, in particular an air-water heat exchanger, such that the heat pump recovers the heat from a separate heat transfer medium intermediate circuit.

[0026] In an alternative embodiment, the machine is characterized in that the heat pump is arranged to recover heat energy at a temperature of the exhaust air flow in the exhaust air duct of greater than or equal to 45°C, preferably greater than or equal to 60°C, and less than or equal to 80°, preferably less than or equal to 70°C.

[0027] In an alternative embodiment, the machine is characterized in that the heat pump is designed in such a way that a steam requirement required during normal operation of the machine, preferably a steam temperature and a steam mass flow, is provided in the steam and condensate system solely by the heat pump.

[0028] In an alternative embodiment, the machine is characterized in that a steam generator included in the steam and condensate system is arranged downstream of the heat pump, preferably a passively functioning or electrically operated steam generator, which is designed to convert a condensate heated to steam temperature by the heat pump into steam.

[0029] Advantageously, a steam generator is used downstream of the heat pump, generating steam from the condensate heated by the heat pump with little or no additional energy input. For example, a passive steam generator can be a throttle through which the heated condensate undergoes flash evaporation.

[0030] In an alternative embodiment, the machine is characterized in that the steam accumulator comprises an electric heating device or a hydrogen burner heating device for maintaining a steam temperature.

[0031] In an alternative embodiment, the machine is characterized in that the steam accumulator is designed such that the steam accumulator has a steam storage time of greater than or equal to 8 hours, preferably greater than or equal to 12 hours, in particular greater than or equal to 72 hours, for the sole supply of the required amount of steam during a warm start of the machine.

[0032] In an alternative embodiment, the machine is characterized in that the steam accumulator is designed such that the steam accumulator stores steam at a steam temperature of greater than or equal to 110°C and a steam pressure level of greater than or equal to 0.4 and less than or equal to 1.5 bar above atmospheric pressure. In an alternative embodiment, the machine is characterized in that the steam and condensate system comprises at least one electrically operated steam compressor, preferably two, three or four electrically operated steam compressors connected in series, designed such that steam in the steam supply line is increased to a steam pressure level of greater than or equal to 5, preferably greater than or equal to 6 and less than or equal to 12, preferably less than or equal to 10, bar above atmospheric pressure.

[0033] The steam compressors used are designed as electrically driven, pure compression units and serve to further compress the existing steam. These steam compressors differ from the so-called thermocompressors commonly used in paper machines.

[0034] In an alternative embodiment, the machine is characterized in that the steam and condensate system comprises a further steam generator, preferably a mobile steam generator, which is designed such that a steam requirement required briefly for the duration of a cold start of the machine, preferably a steam temperature and a steam mass flow, is provided in the steam and condensate system solely until an operating temperature for normal operation of the machine is reached.

[0035] In an alternative embodiment, the machine is characterized in that the exhaust air line can be connected to a drying hood of a drying section, a drying hood of a Yankee drying cylinder, a drying hood of a contactless drying section, a vacuum blower of a drying section and / or a vacuum blower of a forming section.

[0036] The method according to the invention for producing or treating a fibrous web, in particular a paper, cardboard or tissue web, in a machine according to claim 1, is characterized in that the heat pump recovers the remaining thermal energy before a dew point temperature of the exhaust air flow in the exhaust air line is reached and that steam is stored in a steam accumulator arranged downstream of the heat pump and that a set steam requirement of the steam and condensate system a) is provided solely by the heat pump during normal operation of the machine and b) is provided solely by the steam accumulator in the steam and condensate system during a warm start of the machine.

[0037] In a further alternative embodiment, the method is additionally characterized in that c) during a cold start of the machine, a further steam generator, preferably a mobile further steam generator, is arranged in the steam and condensate system in such a way that the required steam requirement until normal operation of the machine is provided by the further steam generator solely and / or in addition to the heat pump.

[0038] In an alternative embodiment, the machine is characterized in that the heat pump is arranged to increase a heating medium flow, preferably a condensate in a condensate return line of the steam and condensate system, by a temperature difference of greater than or equal to 15°K, preferably greater than or equal to 40°K, preferably greater than or equal to 60°K.

[0039] In an alternative embodiment, the machine is characterized in that the steam accumulator is designed as a boiling water accumulator, preferably a Ruth steam accumulator.

[0040] In an alternative embodiment, the machine is characterized in that the steam and condensate system comprises a mixing line downstream of the steam compressor and that the mixing line is connectable to a low-pressure area for mixing the steam to a set steam pressure level.

[0041] In an alternative embodiment, the machine is characterized in that the steam and condensate system comprises a further steam generator, preferably a mobile further steam generator heated with non-fossil fuels, preferably a mobile further steam generator heated with hydrogen, with biogas, geothermally, solar and / or electrically.

[0042] The invention expressly extends to embodiments which are not given by combinations of features from explicit references to the claims, with which the disclosed features of the invention can be combined with one another - as far as this is technically reasonable.

[0043] Corresponding elements of the exemplary embodiments in the figures are provided with the same reference numerals. The functions of such elements in the individual figures correspond to one another unless otherwise stated and unless contradictory. A repeated description is therefore omitted.

[0044] It should also be noted that the differing features of the illustrated embodiments can be interchanged and combined with one another. The invention is therefore not limited to the combinations of features shown in the illustrated embodiments.

[0045] Further features and advantages of the invention will become apparent from the following description of preferred embodiments with reference to the drawings.

[0046] The invention is explained below with reference to the following figures.

[0047] Figures 1a to 1d show schematically illustrated arrangements of the machine according to the invention with a heat pump and a steam accumulator;

[0048] Figure 2 shows a schematic cross-section through a heat pump designed as a compression heat pump;

[0049] Figures 3a to 3e show further schematically illustrated arrangements of the machine with a heat pump. Figures 1a and 3a illustrate, in a schematic and highly simplified representation, the basic structure and basic function of a machine 1 designed according to the invention for producing or treating a fibrous web F, in particular a paper, board, or tissue web F, with a heat pump 90 and a steam accumulator 54.

[0050] The machine 1 comprises at least one drying section 2, 4. In the exemplary arrangement, two drying sections 2, 4 are shown, with at least one further machine section 3 being arranged between the two drying sections 2, 4. This is, for example, an application device or a calender. The machine 1 is shown schematically and in a highly simplified manner and only reproduced with regard to the components relevant to the invention. The otherwise usual other upstream and downstream sections or components of a machine 1 for producing or treating a fibrous web F, such as a headbox, a former, a press, an application device, a calender, a smoothing device and a reel are not shown, since these are assumed to be known.Typically, after leaving the last drying section 4, the fibrous web F is transferred to a subsequent machine section such as a smoothing device and / or the reel.

[0051] To illustrate the individual directions, a Cartesian coordinate system has been created. The x-direction represents the longitudinal direction, also known as the machine direction (MD). The y-direction corresponds to the direction perpendicular to the machine direction and is referred to as the cross-machine direction (CD), while the z-direction corresponds to the vertical direction.

[0052] The flow directions of the different media are illustrated in the figures by a directional arrow in the pipes.

[0053] The fibrous web F typically enters a first drying section 2 shown, wherein the first drying section 2 is divided into several drying sections 21, 22, 23, and a total of five drying sections 21, 22, 23 are shown. The drying sections in the first drying section 2 are further enclosed by two drying hoods 29, which collect or capture the heat energy released and not consumed in the drying sections in the form of exhaust air.

[0054] The machine 1 further comprises a steam and condensate system 5 and a thermal energy recovery system 6. The steam and condensate system 5 is typically used to supply the drying sections 2, 4 with heat in the form of heated, superheated and / or warmed steam. The steam and condensate system 5 is connectable to the drying section 2, 4 and / or the drying sections 21, 22, 23, 41 via a steam supply line 57 and a condensate return line 58. The steam and condensate system 5 typically provides steam with maximum temperatures T_57 of greater than or equal to 100°C to less than or equal to 130°C and a volume or mass flow to supply the drying section 2, 4. The steam consumed in the drying section 2, 4 is returned in the form of condensate in a condensate return line 58 in the closed steam and condensate system 5. Typically, the condensate has a return temperature of T_58 of greater than or equal to 90°C to less than or equal to 100°C.

[0055] Furthermore, a drying section 21 is shown within the first drying section 2 with a further drying hood 291. This can, for example, be a drying section 21 which is designed as a contactless drying section 21, such as an impingement flow drying section 21 or an infrared drying section 21. The contactless drying sections are preferably heated electrically or with hydrogen.

[0056] The second drying section 4 is designed, for example, with a single drying section 41 and drying hood 49. This can advantageously be a drying section 41 designed as a contactless drying section 41, such as an impingement flow drying section 41, or an infrared drying section, preferably heated electrically or with hydrogen.

[0057] The drying section 4 can also be designed, for example, as a high-performance drying hood 49 of a Yankee drying cylinder 41.

[0058] The dryer section 2, 4 can be designed differently in its structure and components; for example, combinations or similar designs of the following exemplary embodiments are conceivable. The dryer section 2, 4 can, for example, be designed as a single-row and / or double-row drying cylinder drying section 21, 22, 23, 41 with enclosing drying hoods 29, 49. Furthermore, the dryer section can, for example, be designed in a tissue machine as a high-performance drying hood 29, 49 on a Yankee drying cylinder, with the Yankee drying cylinder forming a drying section 21, 22, 23, 41.

[0059] Furthermore, another possible source for exhaust air 84 is shown in another machine section 3 of the machine 1. A forming section 3 typically comprises so-called vacuum blowers of the forming section 31 for dewatering the fibrous web F, which provide another exhaust air 84 with residual heat.

[0060] The illustrated drying hoods 29, 291, 49 are connectable to an air supply duct 82 and an exhaust duct 84, with a preferably heated fresh air stream 82 being supplied through the air supply duct 82 to better absorb the released moisture. The heated and moist air generated by the drying of the fibrous web is removed again through the connected exhaust duct 84.

[0061] Advantageously, several exhaust air lines 84 can be connected together, for example, in order to obtain a larger exhaust air volume flow and / or alternatively, if the available heat is significantly higher than the required temperatures for efficient heat energy recovery, they can be further blended or mixed in order to provide an optimal initial temperature level with a higher volume flow for efficient heat energy recovery.

[0062] For efficient utilization of the residual heat, the exhaust air streams 84 are each individually fed to their own heat recovery system 6. Advantageously, each exhaust air line 84 has a separate heat recovery system, which can just as advantageously be interconnected and mixed on the consumer side, for example, to achieve the desired temperatures in a secondary system consumer 70, 71, 72, 73, 74. Another resulting advantage is, for example, when the existing exhaust air volume flows 84, such as in the case of a vacuum blower in a forming section 31, are so large that the dimensions of the exhaust air lines 84, for example in diameter, have to be routed over long distances of the machine 1 and become too complex in terms of cost and manufacturing technology.In this case, a heat exchanger 60, preferably an air-heat transfer medium heat exchanger 60, is installed upstream in an exhaust air duct kept as short as possible, which advantageously transfers the heat with minimal losses into a heat transfer medium intermediate circuit 86. The heat transfer medium 86, preferably water 86, has a high specific heat capacity compared to the exhaust air, so that transport over longer distances in the machine 1 is easier to implement.

[0063] To enable particularly efficient operation of the machine 1, the machine 1 comprises a heat energy recovery system 6 with at least one heat pump 90 for supplying the drying sections 21, 22, 23, 41 included in the drying section 2, 4 with heat, which extracts the necessary heat from an exhaust air line 84, 84' from a machine section. The exhaust air 84, 84' is preferably taken from a drying section 2, 4 and / or directly from a drying section 21, for example, from an included vacuum suction box or an impingement air or hot air drying section 21. The residual heat or temperatures found there are higher than, for example, an exhaust air flow 84 of a vacuum blower of a forming section 31 compared to other exhaust air flows. If higher volume flows are required in the exhaust air flow 84, it is advantageous to admix various exhaust air lines 84 along the entire heat energy recovery system / process 6.Ideally, the outlet temperatures of the mixed exhaust air streams 84 are still above the dew point, thus enabling advantageous recovery of the condensation heat contained therein.

[0064] Further required supply air is taken from the environment 88 of the machine 1, whereby the environment has an ambient temperature and an ambient pressure, usually essentially 1 atm (atmosphere) or 1 bar.

[0065] Furthermore, the steam and condensate system 5 comprises a high-pressure region 51 and a low-pressure region 52, wherein the high-pressure region 51 is characterized in that a steam pressure level of greater than or equal to 5, preferably greater than or equal to 6 and less than or equal to 12, preferably less than or equal to 10, bar above atmospheric pressure is present and in the low-pressure region 52 a steam pressure level of greater than or equal to 0, preferably greater than or equal to 0.4 and less than or equal to 1, preferably less than or equal to 1.5, bar above atmospheric pressure.

[0066] Furthermore, the high-pressure region 51 comprises at least one steam compressor 55, preferably two, three or four steam compressors 55 connected in series, which are designed to increase an existing steam pressure level of the low-pressure region 52 to the set steam pressure level of the high-pressure region.

[0067] The at least one steam compressor 55, preferably the two, three or four steam compressors 55 connected in series, are designed such that a steam in the steam supply line 57 of the drying sections 21, 22, 23, 41 is increased to a steam pressure level of greater than or equal to 5, preferably greater than or equal to 6 and less than or equal to 12, preferably less than or equal to 10, bar above atmospheric pressure.

[0068] The steam and condensate system 5 further includes a steam accumulator 54. The steam accumulator 54 may, for example, be a boiling water accumulator, but may also be another form of steam storage to meet the requirements. The steam accumulator 54 is arranged downstream of the heat pump 90.

[0069] Advantageously, the steam accumulator 54 is designed such that it has a storage time of the heated steam of greater than or equal to 8 hours, preferably greater than or equal to 12 hours, in particular greater than or equal to 72 hours.

[0070] It is advantageous if the storage duration can be achieved without additional heat input, i.e., through passive methods. "Storage duration" essentially means that the heated steam can be maintained at its original temperature and pressure.

[0071] This enables short-term, limited bridging in the event of brief machine downtimes due to possible errors and / or minor maintenance work.

[0072] In an alternative embodiment, the steam storage 54 has an electric heating device or a hydrogen burner heating device for maintaining a boiling water temperature. This can be used when passive methods are not entirely sufficient. Furthermore, the steam and condensate system 5 includes a steam distributor 50, which can distribute the steam into a high-pressure region 51 and a low-pressure region 52.

[0073] The steam and condensate system 5 further comprises a steam generator 53, wherein the steam generator 53 is arranged downstream of the heat pump 90 and the steam generator 53 is passively or electrically heated, and the steam generator 53 is designed such that the steam generator 53 can convert condensate heated to over 110°C in the condensate return line 58' downstream of the heat pump 90 into steam with no or only a minimal supply of electrical energy. Typically, the heat pump is suitable for directly achieving a phase transition from liquid condensate to gaseous vapor when the temperature of the condensate from the condensate return line 58 increases to a heated condensate in the condensate return line 58'. The usual pressure level in the condensate return line 58' is between 0.4 and 1.5 bar above atmospheric pressure and at a temperature of greater than or equal to 100°C and less than or equal to 120°C.

[0074] In the event of a prolonged downtime of the machine 1, in an alternative embodiment, the steam and condensate system 5 can comprise an additional steam generator 56. This can be, for example, a stationary and / or a mobile, temporarily deployed additional steam generator 56. The additional steam generator 56 is preferably a steam generator 56 heated with non-fossil fuels, preferably a steam generator 56 heated with hydrogen, biogas, geothermally, solar, and / or electrically.

[0075] A separate, mobile additional steam generator 56 can usually be planned due to the predictability or planability of a longer downtime and can be arranged specifically only for the required period; this is advantageous from an economic point of view.

[0076] The additional steam generator 56 is designed such that the additional steam generator 56 can briefly cover the steam demand of the thermal energy consumers 5, 70, 71, 72, 73, 74, 82 alone for a cold start of the machine 1. This means that a set steam temperature and a steam mass flow are provided until an operating temperature of the machine 1 is reached. It is further conceivable that the additional steam generator 56 is operated in combination with the heat pump 90 such that the additional steam generator 56 and the heat pump 90 together briefly provide the set steam temperature and the mass flow for a cold start of the machine 1 until an operating temperature of the machine 1 is reached.For example, in a simple case, once a certain temperature level is reached in the exhaust air lung 84, a linear relationship between the additional steam generator and the heat pump can be regulated, so that as the temperature increases until the operating temperature is reached, the heat pump provides an increasing proportion of the steam requirement.

[0077] The additional steam generator 56 can be arranged directly downstream of the steam accumulator 54 and supply the required steam upstream of a steam compressor in the low-pressure region 52 of the steam and condensate system 5. Advantageously, at least one steam compressor 55, for example, shown here with three stages and three steam compressors in series, can then be used to achieve the set steam pressure level, which makes it possible to reduce the required power class of a mobile steam generator 56.

[0078] In an alternative arrangement, the steam generator 56 feeds the required steam entirely into the steam and condensate system 5, essentially directly after the steam compressors 55.

[0079] The steam and condensate system 5 further comprises a mixing line 59, which connects the high-pressure region 51 and the low-pressure region 52 to a secondary system consumer 70, preferably a steam secondary consumer system. It allows a high-pressure steam to be added to a secondary system consumer 70 after one, preferably after two, three, or four steam compressors 55, if a specific pressure level between the existing low pressure and high pressure is required. Figures 1a to 1c, for example, show an arrangement with three steam compressors 55 in series.

[0080] By using the heat pump 90, a lower temperature T_84' can be used compared to the higher temperature T_84 to extract further heat from the exhaust air in the exhaust air duct 84 until a lower temperature 84" or an ambient temperature T_88 is reached. By means of the extracted heat and use of additional electrical energy 80 to operate the heat pump 90, another media stream 58 in a heating medium supply line 97, preferably a condensate in a condensate return line 58 or a secondary system consumer 70, 71, 72, 73, 74, with a temperature T_97 to a higher temperature T_91 or an increased condensate return line temperature 58'. It is important that the temperature, for example, in the exhaust air duct 84 drops after each heat sink or heat exchanger, thus a temperature T_84 greater than or equal to T84' greater than equal to T84" and greater than or equal to T_88.The same applies to the temperatures in the other lines that are routed via a heat sink.

[0081] The structure of a heat pump 90 is shown as an example in Fig. 2. The heat pump 90 extracts residual heat from a heat source, preferably an exhaust air stream in an exhaust air duct 84, 84', 84" or another heat transfer medium 86, 86', preferably water 86, 86', wherein the heat source is connectable to the first heat exchanger 93 of the heat pump via a heat source supply line 92 and a heat source outlet 98. It is characteristic that the temperature in the heat source supply line T_92 is greater than or equal to the temperature in the heat source outlet T_98.

[0082] The heat pump 90, which can be designed, for example, as a compression heat pump 90, comprises a first heat exchanger 93, which is also referred to as a cold heat exchanger 93 or evaporator 93. Furthermore, the heat pump 90 comprises a second heat exchanger 95, which is also referred to as a warm or hot heat exchanger 95 or condenser 95.

[0083] When the heat pump 90 is designed as a compression heat pump, the heat pump 90 further comprises a circuit 99 with a heat transport medium and further an evaporator 93, a compressor 94, an expansion device 96 and a condenser 95. The medium to be heated or heating medium, preferably water or condensate in the condensate return line 58, flows through the condenser 95, wherein the condenser 95 can usually be connected to or supplied with a closed system with a heating medium having a heating medium supply line 97 and a heating medium outlet line 91. The heating medium outlet line 91 is connected in such a way that the necessary consumers and / or secondary system consumers are supplied with heat. It is characteristic that the temperature in the heating medium supply line T_97 is less than or equal to the temperature in the outlet line T_91.

[0084] The first heat exchanger 95 is, for example, a condenser 95, by means of which the heat transport medium contained in the circuit 99 of the heat pump 90 is condensed. The heat transport medium is expanded by means of the expansion device 96, while the second heat exchanger 93 is, for example, an evaporator 93, by means of which the heat transport medium is evaporated. Finally, the heat transport medium can be recompressed by means of the compressor 94. To drive the compressor 94, the motor is supplied with electrical energy, so that the heat transport medium can be compressed by the compressor 94 with the aid of electrical energy 80 or electrical current 80 and thus heated.

[0085] As shown, the first heat exchanger 93 can alternatively be connected by different media flows 84, 86, preferably air and / or water, or media flows with different temperature levels 84, 84' from which residual heat is to be recovered.

[0086] Alternatively, the first heat exchanger 93 may also be a component of an upstream, separate further heat exchanger 60, 61 or a separate air heater.

[0087] Alternatively, the second heat exchanger 95 may also be a component of a downstream, separate, further heat exchanger 60, 61 or a separate air heater.

[0088] Furthermore, it is conceivable that the heat pump 90 is designed as a thermochemical heat pump 90. In the thermochemical heat pump 90, a chemical, heat-absorbing, and thus endothermic, reaction is effected by means of heat supplied to the heat pump 90.

[0089] Figure 1a shows an arrangement of the heat pump 90 within the thermal energy recovery system 6, marked with a dashed box. The exhaust air duct 84 from the machine 1, at a typical temperature of greater than or equal to 75°C to 90°C, is fed to a first heat exchanger 60 arranged upstream of the heat pump 90. In the arrangement shown, a first portion of the residual heat still contained in the exhaust air 84 is transferred to the supply air 82 or supply air duct 82 flowing in from the environment of the machine 1.

[0090] Advantageously, in this arrangement, the upstream or first heat exchanger 60 is designed as an air-air heat exchanger 60.

[0091] The exhaust air 84' leaving the first heat exchanger 60 now has a lower temperature T_84' than the temperature T_84 of the incoming exhaust air 84.

[0092] The exhaust air flow 84' passed through the first, upstream heat exchanger 60 is now fed to the heat pump 90, or to the first heat exchanger 93 of the heat pump 90, via the heat source supply line 92, and thus a further part of the residual heat still contained in the exhaust air 84' is further utilized.

[0093] At the same time, the heating medium to be heated is supplied to the heat pump 90 through the condensate return line 58 at a temperature T_58 via the heating medium supply line 97. By simultaneously supplying electrical energy 80, the heating medium is heated by the heat pump 90 to a higher temperature level T_58' in the heating medium outlet 91, and the exhaust air 84' is cooled to a lower temperature, here to ambient temperature T_88, or discharged into the environment 88 through the heat source outlet 98.

[0094] Advantageously, the heat pump 90 is suitable for recovering heat energy at a temperature T_84 in the exhaust air line 84 of greater than or equal to 55°C, preferably greater than or equal to 60°C, and less than or equal to 80°C, preferably less than or equal to 70°C, particularly energy-efficiently.

[0095] The heated heating medium 58', preferably the condensate, is provided to the steam and condensate system 5 at a set temperature level T_58' of greater than or equal to 100°C, preferably greater than or equal to 110°C, and less than or equal to 130°C, preferably less than or equal to 120°C.

[0096] The heat pump 90 is suitable for increasing the temperature of a condensate in the condensate return line 58 by a temperature difference of greater than or equal to 40°K, preferably greater than or equal to 60°K. Figure 1b only shows the area of ​​the thermal energy recovery system 6 and the steam and condensate system 5 and the corresponding supply lines and discharge lines, which are included in the machine 1, as shown in Figure 1a. Furthermore, Figure 1b shows an arrangement of the heat pump 90 within the thermal energy recovery system 6 marked with a dashed box, wherein the steam accumulator 54 is essentially arranged directly downstream of the heat pump 90 and thus does not have an additional steam generator 53, as shown in Figure 1a. Furthermore, an alternative arrangement of the preferably mobile additional steam generator 56 in the high-pressure area 51 after the last steam compressor 55 is shown.Furthermore, a second thermal energy recovery system 6 is shown, marked with another dashed box. The second thermal energy recovery system 6 for a second secondary system consumer 71 comprises a further heat exchanger 62, which transfers the heat of the steam to another separate secondary system consumer circuit. This can advantageously be an air- or water-convection system. The steam conducted through the further heat exchanger 62 is fed via a recirculation line to the condensate return line 58 and thus reheated via the heat pump arrangement.

[0097] Furthermore, the exhaust air line 84 from the machine 1, at a typical temperature of greater than or equal to 75°C to 90°C, is fed to a first heat exchanger 60 arranged upstream of the heat pump 90. In the illustrated arrangement, a first portion of the residual heat still contained in the exhaust air 84 is transferred to the supply air 82 or supply air line 82 flowing in from the environment of the machine 1, which is supplied from the environment 88.

[0098] The exhaust air 84' leaving the first heat exchanger 60 now has a lower temperature T_84' than the temperature T_84 of the incoming exhaust air 84. Advantageously, in this arrangement, the upstream or first heat exchanger 60 is designed as an air-to-air heat exchanger 60.

[0099] The exhaust air stream 84' passed through the first, upstream heat exchanger 60 is then passed downstream through a further, second heat exchanger 61, which is advantageously designed as an air-to-heat-transfer medium heat exchanger 61. The second heat exchanger 61 transfers the residual heat contained in the exhaust air 84' to a separate, preferably closed, intermediate heat-transfer medium circuit 86, 86'. The heat-transfer medium 86 can advantageously be water or a heat-transfer medium with high heat capacity.

[0100] The heat transfer medium intermediate circuit 86, 86' is now fed to the heat pump 90, or to the first heat exchanger 93 of the heat pump 90, via the heat source supply line 92, and thus a further part of the residual heat still contained in the exhaust air 84' before the second heat exchanger 61 and transferred into the separate heat transfer medium intermediate circuit 86 is further utilized.

[0101] The arrangement shown in Figure 1b, with a second, intermediate heat exchanger 61 and a closed, intermediate heat transfer medium circuit 86, 86' upstream of the heat pump 90, is advantageously selected when a condition of the exhaust air must be expected that, for example, is aggressive towards the materials used in the heat exchanger. For example, the moist exhaust air can be corrosive and there is a risk that the heat exchanger 93 of the heat pump 90 will be attacked. This successfully prevents corrosion of the heat exchanger 93 of the heat pump 90, which, under certain conditions, can release the heat transfer medium contained in the circuit 99. This is particularly advantageous when the heat pump 90 is filled with special heat transfer media, which, if they escape from the circuit 99, can be harmful to the environment and / or pose a risk of explosion.Further advantageously, the heat transfer medium intermediate circuit 86, 86' can be designed such that the intermediate circuit has a sufficiently high heat capacity or heat storage, similar to the integrated steam accumulator 54. Such a dimensioned intermediate circuit can temporarily compensate for the departing heat source or exhaust air 84 with sufficient thermal energy in the event of an unplanned or planned machine downtime, for example, in the event of a breakdown. This advantageously enables short-term continued operation of the included components and advantageously prevents damage due to excessive temperature gradients in the heat pump.

[0102] At the same time, the heating medium to be heated is supplied to the heat pump 90 through the condensate return line 58 at a temperature T_58 via the heating medium supply line 97. By simultaneously supplying electrical energy 80, the heating medium is heated by the heat pump 90 to a higher temperature level T_58' in the heating medium discharge line 91, and the return of the separate heat transfer medium intermediate circuit 86' is cooled to a lower temperature T_86'.

[0103] The heated heating medium 58', preferably the condensate, is provided to the steam and condensate system 5 at a set temperature level T_58' of greater than or equal to 100°C, preferably greater than or equal to 110°C, and less than or equal to 130°C, preferably less than or equal to 120°C.

[0104] The heat pump 90 is suitable for increasing a temperature of a condensate in the condensate return line 58 by a temperature difference of greater than or equal to 40°K, preferably greater than or equal to 60°K.

[0105] Advantageously, the heat pump 90 is suitable for recovering heat energy at a temperature T_84 in the exhaust air line 84, 84' of greater than or equal to 55°C, preferably greater than or equal to 60°C, and less than or equal to 80°C, preferably less than or equal to 70°C, particularly energy-efficiently.

[0106] Figure 1 c shows an alternative arrangement to the arrangement shown in Figure 1 b, wherein a further heat exchanger 63, which is advantageously designed as an air-air heat exchanger 63, is arranged downstream of the heat pump 90 within the heat energy recovery system 6 marked with a dashed box.

[0107] The downstream further heat exchanger 63 supplies a further, third secondary consumer system 72 with the exhaust air 84" of the previous heat exchanger 61 and uses a further part of the residual heat still contained in the exhaust air 84".

[0108] Furthermore, in Figure 1c, the additional mobile steam generator 56 in the low-pressure region 52 is arranged upstream of the steam compressors 55, and the preferably passive or electrically heated steam generator 53 is arranged essentially directly downstream of the heat pump 90. Figure 1d shows an alternative arrangement to the arrangement shown in Figure 1b, wherein a further heat exchanger 63, which is advantageously designed as an air-to-air heat exchanger 63, is arranged downstream of the heat pump 90 within the thermal energy recovery system 6 marked with a dashed box.

[0109] The downstream additional heat exchanger 63 supplies the dryer hood supply air heating 82, which is also a secondary consumer system, with the exhaust air 84' of the preceding heat exchanger 61 and uses a further part of the residual heat still contained in the exhaust air 84'.

[0110] Furthermore, in Figure 1 d, the further mobile steam generator 56 in the high-pressure area 51 is arranged downstream of the steam compressors 55 and the steam generator 53, which is preferably passive or electrically heated, is arranged essentially directly downstream of the heat pump 90.

[0111] Furthermore, in Figure 1 d, the heat exchanger 61 arranged upstream of the heat pump 90 is supplied directly with the exhaust air 84 via a separate heat transfer medium intermediate circuit 86.

[0112] The exhaust air 84" leaving the downstream heat exchanger 63 now has a lower temperature T_84" than the temperature T_84' of the incoming exhaust air 84' or is discharged into the environment 88.

[0113] In an alternative embodiment not shown, the exhaust air line 84 from the machine 1 can be fed directly to the heat pump 90 at a typical temperature of greater than or equal to 75°C to 90°C. The supplied exhaust air stream 84 is fed to the heat pump 90, or rather, the first heat exchanger 93 of the heat pump 90, via the heat source supply line 92, and a first portion of the residual heat contained in the exhaust air 84 is further utilized. No further heat exchanger 60 is connected upstream of the heat pump 90.

[0114] Figures 3a to 3e show further alternative arrangements of at least one heat pump 90 in the machine 1. The heat pump 90 is advantageously included in the heat energy recovery system 6 of the machine 1, indicated by a dashed box. The heat energy recovery systems 6 of the machine 1 are advantageously also used for the energy-efficient supply of required heat in other secondary system consumers 70, 71, 72, 73, 74.

[0115] Figure 3a shows an arrangement of a heat pump 90, which is arranged downstream of a first heat exchanger 60. The exhaust air flow 84" is subsequently passed through a second heat exchanger 61, followed by another heat pump 90 and a third heat exchanger 62 for energy-efficient heat energy recovery and the possibility of increasing the heat energy to a slightly higher temperature level, if required. Advantageously, the set temperature differences in a second heat pump are in the range of dT = 15°K.

[0116] Furthermore, the first heat exchanger 60 heats, for example, the supply air 82 for the drying hoods 29, 39, 49 of a drying section 2, 4 from the environment 88. The first heat pump 90 supplies the steam and condensate system 5, the second heat exchanger 61 supplies a first secondary system consumer circuit 70, the second heat pump 90 supplies a second, further secondary system consumer circuit 71, and the third heat exchanger 62 supplies a third, further secondary system consumer circuit 72. The decisive factor for such a multi-stage arrangement is that the temperature levels required to supply the secondary system consumer circuits 70, 71, 72 are further lowered or reduced as the components progress, and the greatest possible part of the thermal energy contained in the exhaust air 84 is recovered, and the temperature T_84 is cooled approximately to ambient temperature T_88.It is crucial that the separate heat exchangers 60, 61, 62, 63, 64 used or the heat exchangers 93 included in the heat pump 90 are designed in such a way that they have large heat exchanger transfer surfaces for the efficient exchange of heat energy in order to heat the greatest possible recovered heat energy with a low energy requirement 80 of the heat pump 90 to the required temperature level or heat level.

[0117] At the same time, the maximum heat exchanger transfer area is limited due to manufacturing and cost considerations. Secondary system consumers 70, 71, 72, 73, 74 with reduced or low temperature levels can be connected, for example, to the dryer hood supply air 82, the process water heating, the hall ventilation or heating, and the supply to steam blow boxes in the drying sections.

[0118] For the secondary system consumers, after adjusting the heat exchanger transfer surfaces in the heat pump 90 or the separate heat exchangers 60, 61, 62, 63, 64 during operation of the machine 1, a lower, so-called temperature spread results, which is determined via the temperature difference in the heat pump 90 between the temperature in the heat exchanger 93 or the evaporator 93 and the temperature in the heat exchanger 95 or the evaporator 95. The temperature difference usually used, for example for hall ventilation or hall heating on the heating medium side of the heat exchanger, is between greater than or equal to 18°K and less than or equal to 22°K, preferably 20°K. This allows the usual high inlet and return temperatures of 25°C to 50°C to be achieved.To achieve the usual hall temperature of 20°C to 25°C, the modified heat exchangers on the heating medium side are only operated with reduced inlet and return temperatures of 20°C to 40°C and a temperature difference of greater than or equal to 13°K to less than or equal to 18°K, preferably essentially 15°K.

[0119] A heat deficit still present in a subsequent secondary system consumer 72, 73, 74, for example in the heating water or process water system, but also at other points in the paper production process with heat requirements at a temperature level of up to 60°C can be compensated by a second, downstream heat pump 90, whereby this second heat pump then again operates with a small temperature difference and thus very efficiently.

[0120] Figure 3b shows only the area of ​​the thermal energy recovery system 6 and the corresponding supply and discharge lines, which are included in the machine 1, as shown in Figure 1a or 3a. Figure 3b also shows an arrangement in which the exhaust air flow 84 is fed directly into a heat pump 90, for example, to supply the dryer hood supply air 82. Two further heat exchangers 60, 61 for thermal energy recovery with associated secondary consumers 70, 71 are then arranged downstream of the heat pump 90.

[0121] Advantageously, a heat pump 90 operates more efficiently the smaller the temperature lift or temperature difference to be achieved. Arranging the first heat exchanger 93 or the evaporator 93 of a heat pump 90 as the first stage for heat recovery in an exhaust air duct 84 is therefore particularly advantageous.

[0122] Figure 3c shows an alternative arrangement to the arrangement shown in Figure 3a, wherein the heat pump 90 supplies a secondary system consumer 70 and three heat exchangers 61, 62, 63 are arranged downstream of the heat pump 90, and each heat exchanger 61, 62, 63 supplies a secondary system consumer 71, 72, 73. It is characteristic that the downstream secondary system consumers are further reduced in temperature.

[0123] Figure 3d shows an alternative arrangement to the arrangement shown in Figure 3a, wherein the heat pump 90 arranged downstream of the first heat exchanger 60, a separate heat transfer medium intermediate circuit 86, 86', and a further heat exchanger 61 are arranged upstream of the heat pump 90. Analogous to Figures 1c and 1d, this results in the explained advantages. The exhaust air stream 84 is passed through a first heat exchanger 60, for example to supply the dryer hood supply air 82. The exhaust air stream 84' is passed through a further downstream heat exchanger 61, preferably an air-heat transfer medium heat exchanger 61. The further heat exchanger 61 exchanges the heat with a downstream heat pump 90 via a separate heat transfer medium intermediate circuit 86.The additional heat exchanger 61 can be followed by a further heat exchanger 62 in the exhaust air line 84" to supply a secondary system consumer 72 before the exhaust air 84" has reached an ambient temperature 88. In a parallel thermal energy recovery system 6, a secondary system consumer 70 is efficiently heated to a required temperature by the heat pump 90. It is also conceivable to connect several, preferably two, heat pumps 90 shown in series one after the other to supply additional secondary system consumers 70, 71, or a combination can be achieved with a heat pump bypass line 89, whereby the second heat pump 90 can be switched on when demand increases.

[0124] Figure 3e shows an arrangement in which the exhaust air stream 84 is passed through a first heat exchanger 60, preferably an air-to-heat transfer medium heat exchanger 60. The heat exchanger 60 exchanges the heat via a separate heat transfer medium intermediate circuit 86 with a downstream, first heat pump 90. This first heat pump 90 heats fresh air from the environment 88 of the machine 1 and is supplied as heated dryer hood supply air 82 to the dryer hoods 29, 39, 49 of the dryer section 2, 4. Due to a small temperature difference, this first heat pump 90 operates particularly efficiently. A further heat exchanger 61 can be connected downstream of the heat exchanger 60 in the exhaust air line 84' to supply, for example, the steam and condensate system 5 via a further, second heat pump 90 and a separate heat transfer medium intermediate circuit 86, since the exhaust air 84" can still be corrosive to the materials in the heat exchanger.

[0125] Furthermore, further heat can be extracted from the exhaust air 84" by a further heat exchanger 62, which in this arrangement can be used to supply a secondary system consumer 70.

[0126] Before the exhaust air 84 has reached an ambient temperature 88, a further, third heat pump 90 is arranged directly in the exhaust air flow 84'", which extracts the remaining heat from the exhaust air 84'" and heats it particularly efficiently by the third heat pump 90 to a usable temperature level for another secondary system consumer 71.

[0127] The addition or removal of heat energy into or from a "line" means that the medium moving in the line at a certain temperature and mass and volume flow, for example air, water, preferably steam and / or condensate or a special heat transfer medium, releases or absorbs the heat energy. The "optimal COP" of a heat pump means that the heat pump is operated at the most efficient operating point with the highest efficiency for the requested or required temperature difference dT and can therefore provide many times the heat energy from the added energy, usually electrical. The optimal COP increases with a smaller requested temperature difference. For example, with a temperature difference of dT=60°K, theoretical COP values ​​of approximately 3 are achievable; for example, with a temperature difference of dT=15°K, theoretical COP values ​​of approximately 10 are achievable.The temperature difference between the first heat exchanger and the second heat exchanger of the heat pump is measured. To achieve the most energy-efficient operation possible, it is advantageous to position the heat pump as early as possible to recover condensation heat from the exhaust air stream.

[0128] A "cold start" of a machine means that all possible storage devices have been used up and the temperature of the machine and its components is essentially the same as the ambient temperature. This typically occurs after a prolonged downtime, such as a modernization or remodeling project.

[0129] A "warm start" of a machine means that sufficient heat is still stored in the machine and the machine is restarted from a standstill. This usually occurs after a short downtime, such as a minor fault such as a web break or a brief maintenance operation.

[0130] The term “heat source” is understood to mean a media flow or a heat transfer medium flow, preferably an exhaust air flow 84 and / or water flow 86, with residual heat from a machine section 2, 3, 4 of the machine 1, wherein the residual heat from the “heat source” is utilized.

[0131] The term “heat sink” or “heat consumer” is understood to mean a medium flow or a heating medium flow, preferably a supply air flow 82 and / or water, steam and condensate flow 57, 58, preferably for a heat consumer such as a steam condensate system 5 or a so-called secondary system consumer 70, 71, 72, 73, 74, for example a dryer hood supply air heating system 82, wherein heat is supplied to the heat sink.

[0132] The "dew point" temperature is the temperature in a medium, preferably a heat transfer medium, in particular a humid exhaust air 84, 84', 84", at which the condensation of the contained gaseous portion, preferably the moisture, takes place. The dew point is characterized by the fact that the vapor saturation pressure is equal to the vapor partial pressure of the medium.

[0133] List of reference symbols

[0134] 1 machine

[0135] 2 Dry section

[0136] 21 Dry section

[0137] 22 Drying section

[0138] 23 Drying section

[0139] 29 Drying hood

[0140] 291 Drying hood of a drying section

[0141] 3 more machine batches

[0142] 31 Vacuum blower of a forming section

[0143] 4 Drying section

[0144] 41 Drying section

[0145] 49 Drying hood

[0146] 5 Steam and condensate system

[0147] 50 steam distributors

[0148] 51 High pressure area

[0149] 52 Low pressure range

[0150] 53 steam generators

[0151] 54 steam storage

[0152] 55 Dam pfkom pressor

[0153] 56 additional steam generators

[0154] 57 Steam supply line

[0155] 58 Condensate return line

[0156] 58' Condensate return line with increased temperature compared to 58

[0157] 59 Mixing line high pressure-low pressure area

[0158] 6 Heat energy recovery system

[0159] 60 heat exchangers

[0160] 61 additional heat exchangers

[0161] 62 additional heat exchangers

[0162] 63 additional heat exchangers

[0163] 70 secondary system consumers 71 additional secondary system consumers

[0164] 72 additional secondary system consumers

[0165] 73 additional secondary system consumers

[0166] 74 additional secondary system consumers

[0167] 80 electrical power supply

[0168] 82 Supply air line drying hood, supply air flow

[0169] 84 Exhaust air duct drying hood, exhaust air flow

[0170] 84' Low temperature exhaust air duct compared to 84 (T_84>=T84'>=T84")

[0171] 84" low temperature exhaust duct compared to 84'(T_84>=T84'>=T84")

[0172] 85 non-fossil fuel supply, preferably hydrogen supply

[0173] 86 Separate heat transfer medium intermediate circuit, preferably water

[0174] 86' Heat transfer medium intermediate circuit with higher temperature T_86' than T_86

[0175] 88 Environment, ambient line, ambient temperature, ambient pressure

[0176] 89 By-pass return line, additional heat exchanger intermediate circuit

[0177] 90 heat pump

[0178] 91 Heating medium drainage, preferably water or condensate

[0179] 92 Heat source supply line

[0180] 93 Heat exchangers, evaporators

[0181] 94 Compressor

[0182] 95 Heat exchanger, condenser

[0183] 96 Relaxation organ

[0184] 97 Heating medium supply line, preferably water or condensate

[0185] 98 Heat source dissipation

[0186] 99 Cycle

[0187] F Fibrous web

[0188] T Temperature

[0189] MD Machine direction

[0190] CD Cross machine direction x, y, z coordinates

Claims

Patent claims 1. Machine (1) for producing or treating a fibrous web (F), in particular a paper, board or tissue web (F), comprising at least one drying section (2, 4) and at least one steam and condensate system (5) and at least one thermal energy recovery system (6), and wherein the at least one drying section (2, 4) comprises at least one exhaust air line (84) and at least one drying section (21, 22, 23, 41), and wherein the steam and condensate system (5) comprises at least one steam supply line (57) and at least one condensate return line (58), and wherein the thermal energy recovery system (6) comprises at least one heat pump (90), and wherein the at least one drying section (21, 22, 23, 41) is connectable to the steam and condensate system (5) by the steam supply line (57) and the condensate return line (58) and is substantially completely or partially can be supplied with steam, and wherein the at least one drying section (2,4) and the at least one steam and condensate system (5) are operatively connected via the at least one thermal energy recovery system (6), such that the heat pump (90) partially extracts residual thermal energy from an exhaust air stream of the at least one exhaust air line (84, 84', 84") and, with the additional supply of electrical energy (80), supplies thermal energy to a condensate of the at least one condensate return line (58), characterized in that the at least one heat pump (90) is arranged in the exhaust air line (84) such that the heat pump (90) recovers the residual thermal energy before a dew point temperature of the exhaust air stream in the exhaust air line (84, 84', 84") is reached, and in that the steam and condensate system (5) comprises a steam accumulator (54) arranged downstream of the heat pump (90) for storing the steam. Machine (1) according to claim 1, characterized in that at least one further heat exchanger (60) is arranged upstream of the heat pump (90) in the exhaust air line (84), preferably an air-to-air heat exchanger (60) or an air-to-heat transfer medium heat exchanger (60). Machine (1) according to claim 1 or 2, characterized in that a further heat exchanger (61) is arranged upstream of the heat pump (90) in the exhaust air line (84), preferably an air-to-heat transfer medium heat exchanger (61), in particular an air-to-water heat exchanger (61), such that the heat pump (90) recovers the heat from a separate heat transfer medium intermediate circuit (86, 86').Machine (1) according to one of the preceding claims, characterized in that the heat pump (90) is arranged such that it recovers heat energy at a temperature, preferably dew point temperature, of the exhaust air flow in the exhaust air line (84, 84', 84") of greater than or equal to 45°C, preferably greater than or equal to 60°C, and less than or equal to 80°C, preferably less than or equal to 70°C. Machine (1) according to one of the preceding claims, characterized in that the heat pump (90) is designed such that a steam requirement required during normal operation of the machine (1), preferably a steam temperature and a steam mass flow, in the steam and condensate system (5) is provided solely by the heat pump (90).Machine (1) according to one of claims 1 to 4, characterized in that the heat pump (90) is followed by a steam generator (53) included in the steam and condensate system (5), preferably a passively functioning or electrically operated steam generator (53) which is designed in such a way. to convert condensate (58) heated to steam temperature by the heat pump (90) into steam.

7. Machine (1) according to one of the preceding claims, characterized in that the steam accumulator (54) comprises an electric heating device (80) or a hydrogen burner heating device (85) for maintaining a steam temperature.

8. Machine (1) according to one of the preceding claims, characterized in that the steam accumulator (54) is designed such that the steam accumulator (54) has a storage time of the steam of greater than or equal to 8 hours, preferably greater than or equal to 12 hours, in particular greater than or equal to 72 hours, for the sole supply of the required amount of steam during a warm start of the machine (1).

9. Machine (1) according to one of the preceding claims, characterized in that the steam accumulator (54) is designed such that the steam accumulator (54) stores steam at a steam temperature of greater than or equal to 110°C and a steam pressure level of greater than or equal to 0.4 and less than or equal to 1.5 bar above atmospheric pressure.

10. Machine (1) according to one of the preceding claims, characterized in that the steam and condensate system (5) comprises at least one electrically operated steam compressor (55), preferably two, three or four series-connected and electrically operated steam compressors (55), designed such that a steam in the steam supply line (57) is increased to a steam pressure level of greater than or equal to 5, preferably greater than or equal to 6 and less than or equal to 12, preferably less than or equal to 10, bar above atmospheric pressure.

11. Machine (1) according to one of the preceding claims, characterized in that the steam and condensate system (5) comprises a further steam generator (56), preferably a mobile steam generator (56), which is designed in such a way that a steam requirement required briefly for the duration of a cold start of the machine (1), preferably a steam temperature and a steam mass flow, is provided in the steam and condensate system (5) solely until an operating temperature for normal operation of the machine (1) is reached.

12. Machine (1) according to one of the preceding claims, characterized in that the exhaust air line (84) can be connected to a drying hood (29, 291, 49) of a drying section (2, 4), a drying hood (29, 291, 49) of a Yankee drying cylinder, a drying hood (291) of a contactless drying section (21, 22, 23, 41), a vacuum blower of a drying section (21, 22, 23, 41) and / or a vacuum blower of a forming section (31).

13. A method for producing or treating a fibrous web (F), in particular a paper, cardboard or tissue web (F), in a machine (1) according to claim 1, characterized in that the heat pump (90) recovers the remaining thermal energy before a dew point temperature of the exhaust air flow in the exhaust air line (84, 84', 84") is reached, and in that steam is stored in a steam accumulator (54) arranged downstream of the heat pump (90), and in that a set steam requirement of the steam and condensate system (5) a) during normal operation of the machine (1) is provided solely by the heat pump (90), and b) during a warm start of the machine (1) is provided solely by the steam accumulator (54) in the steam and condensate system (5). Method according to claim 13, characterized in that additionally c) during a cold start of the machine (1), a further steam generator (56), preferably a mobile further steam generator (56), is arranged in the steam and condensate system (5) in such a way that the required steam requirement until normal operation of the machine (1) is provided by the further steam generator (56) solely and / or in addition to the heat pump (90). Machine (1) for producing or treating a fibrous web (F), in particular a paper, cardboard or tissue web (F), comprising at least one machine section (2, 3, 4), preferably a drying section (2, 4) or forming section (3), and at least one thermal energy consumer, preferably a steam and condensate system (5) and / or a secondary system consumer (70, 71, 72, 73, 74, 82), and at least one thermal energy recovery system (6), and wherein the at least one machine section (2, 3, 4) comprises at least one exhaust air line (84),and wherein the thermal energy recovery system (6) is arranged in the at least one exhaust air line (84) and comprises at least one heat pump (90), and wherein the at least one machine section (2, 3, 4) and the at least one thermal energy consumer are operatively connected via the at least one thermal energy recovery system (6) such that the heat pump (90) partially extracts residual thermal energy from an exhaust air flow of the at least one exhaust air line (84, 84', 84") and supplies thermal energy to a heating medium flow of the one thermal energy consumer (5, 70, 71, 72, 73, 74, 82) with an additional supply of electrical energy (80), characterized in that, the at least one heat pump (90) is arranged in the exhaust air duct (84, 84', 84") such that the heat pump (90) recovers the remaining heat energy before a dew point temperature of the exhaust air flow in the exhaust air duct (84, 84', 84") is reached.

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