Film stretching system with a solar thermal process temperature control system

Description

Field of invention

[0001] The present invention relates to a film stretching system comprising a solar thermal process temperature control system. background

[0002] Film production, and in particular the operation of film stretching plants on an industrial scale, is associated with high energy consumption.

[0003] For film production, a starting material, typically at least a polymer, is provided in granule and / or powder form and converted into a film, for example a biaxially oriented film, in several process steps, which typically have different temperature levels.

[0004] The largest energy consumers within this film manufacturing process are typically the drying of the polymeric starting material (e.g., granules and / or powder), extrusion, and mono- or biaxial stretching. Stretching is carried out, for example, using a longitudinal stretching machine (also known as an MDO (Machine Direction Orienter)), a transverse stretching machine (also known as a TDO (Transverse Direction Orienter)), or a simultaneous stretching machine, in which the film is stretched simultaneously in both the transverse and longitudinal directions.

[0005] In film production, the starting material (granules and / or powder) is typically fed first into one (or more) extruder(s). A typical extruder comprises a temperature-controlled (heated) cylinder in which one or two plasticizing screws can rotate. The screw(s) are responsible for conveying the plastic granules (or powder) and the molten plastic formed downstream, melting and homogenizing the starting material through shear (friction), and generating sufficient pressure to continuously force the molten plastic through a shaping die. Different extrusion dies can be used depending on the type of film being produced.

[0006] In blown film production (blown film line), the molten plastic is forced through a (temperature-controlled) die with an annular tip after extrusion. The resulting molten film tube is inflated with air and cooled by (temperature-controlled) cooling air from the outside and, if necessary, from the inside. The cooled film tube is then flattened and wound up.

[0007] In flat film production (also known as flat film extrusion), the molten plastic is typically formed into a flat film after extrusion using a (temperature-controlled) slot die. The film formed by the slot die (also known as cast film) can, for example, be extruded onto a cooling roll and then stretched.

[0008] A film can generally be stretched sequentially or simultaneously. In sequential stretching, the film is first stretched lengthwise and then crosswise. In simultaneous stretching, the stretching in the longitudinal and crosswise directions occurs at the same time.

[0009] The longitudinal stretching (MDO step) of the plastic film typically involves tempering the extruded plastic web and guiding the (cast) film over (tempered) rollers. The rollers, rotating at different speeds, stretch the plastic web lengthwise.

[0010] The subsequent transverse stretching (TDO step) of the plastic film in the case of sequential stretching typically involves tempering the extruded plastic web (in an oven) and then stretching it transversely. For this, the film is typically clamped and then stretched laterally. The biaxially stretched film can then be wound up.

[0011] In simultaneous stretching, the extruded film is first tempered and then fed into a simultaneous stretching machine (e.g., a simultaneous stretching oven). In the simultaneous stretching machine, the film is typically clamped in place and then stretched in width and length.

[0012] In the respective ovens, as typically used for transverse and simultaneous stretching, the film to be stretched is heated before the stretching process and also kept at a predetermined temperature during the stretching process. The stretched film can then be cooled in the oven.

[0013] Simultaneous longitudinal and transverse stretching, in particular, requires a significant amount of thermal energy. Currently, various generation concepts exist for this purpose (e.g., electric heating, heating via thermal oil, heat input via gas burners, and the like). When using thermal oil, the oil is heated via a heating system, such as an oil, gas, or coal boiler. This means that fossil fuels (coal, gas, oil, etc.) are still predominantly involved, resulting in an unfavorable CO₂e footprint for the manufactured film.

[0014] CN 205 202 225 U concerns a boiler system for rubber processing. The system comprises a gas-fired oil-fired boiler, an energy storage unit, and a solar collector.

[0015] WO 2012 / 110 328 A2 discloses a method for operating a directly heated, solar thermal steam generator and DE 20 2019 000 308 U1 discloses a solar-wind hybrid plant.

[0016] The object of the present invention is therefore to eliminate the aforementioned disadvantages and to reduce, or even avoid, the use of fossil fuels for film production. In particular, CO₂e emissions are to be saved. Description of the invention

[0017] The problem is solved by a film stretching system according to claim 1. Further aspects of the invention are part of the dependent claims.

[0018] In particular, the task is solved by a film stretching system which includes a solar thermal process temperature control system. The process temperature control system includes at least one solar heat generator which is integrated into a heat generation circuit, wherein the heat generation circuit carries a first heat transfer fluid.

[0019] The solar thermal energy generator converts solar energy into usable thermal energy. In particular, at least one solar thermal energy generator includes solar thermal collectors that concentrate the incident radiation (e.g., Concentrated Solar Power - CSP systems) to heat the first heat transfer fluid to the highest possible temperatures.

[0020] For example, the solar heat generator can heat the first heat transfer fluid to at least 250°C, at least 300°C, at least 400°C, at least 450°C, at least 500°C, or at least 550°C. Furthermore, the process temperature control system includes at least one heat storage tank. Thermal energy generated by the solar heat generator can be supplied to the heat storage tank via the first heat generation circuit. The heat storage tank is therefore designed to store thermal energy.

[0021] Depending on its design, the storage medium used, the size of the heat storage unit, and its thermal insulation, the heat storage unit can be used as a short-term or long-term heat storage unit. A short-term heat storage unit allows for the storage of a quantity of heat for heating the consumer(s) independently of sunlight for a few minutes up to an hour. With a long-term heat storage unit, the consumer(s) can be heated independently of sunlight for several hours (for example, at least 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 hours).

[0022] The storage medium used by the heat storage system can be the primary heat transfer fluid (direct storage) or an intermediate circuit heat transfer fluid (indirect storage). Other storage media can also be used.

[0023] The process temperature control system further comprises at least one heat consumer circuit that carries a second heat transfer fluid. This second heat transfer fluid can differ from the first. Likewise, the same heat transfer fluid can be used for both the first and second heat transfer fluids.

[0024] The heat consumer circuit is connected to at least one heat storage unit in order to be able to extract stored thermal energy.

[0025] In particular, the heat consumer circuit can comprise a supply section and a return section, whereby the consumer(s) can be integrated into the heat consumer circuit between the supply section and the return section, such that the temperature of the second heat transfer fluid in the supply section is higher than the temperature of the second heat transfer fluid in the return section.

[0026] The process temperature control system further comprises at least one temperature control device. The temperature control device includes at least one heat transfer fluid outlet for supplying the consumer(s). The heat transfer fluid outlet is thus located between the supply section and the return section.

[0027] The at least one temperature control device is configured to supply the second heat transfer fluid at a defined temperature to the at least one heat transfer fluid output (and thus to the consumer(s)) in order to supply at least one component of the film stretching machine directly or indirectly with heat transfer fluid at a defined temperature. In this way, the film stretching machine can be supplied with thermal energy.

[0028] The process temperature control system thus makes it possible to supply thermal energy to the film stretching machine, which is generated by at least one solar heat generator. This enables the reduction of CO2e emissions.

[0029] The process temperature control system can further include a first heat exchanger. This first heat exchanger can be connected between at least one heat storage unit and the heat consumer circuit. In particular, the first heat exchanger can be controlled and / or regulated so that the thermal energy transferred from the heat storage unit to the heat consumer circuit can be controlled. For example, the inflow and / or outflow (e.g., flow rate, flow volume, etc.) of the heat exchanger can be controlled and / or regulated. Thus, the temperature of the second heat transfer fluid in the supply section of the heat consumer circuit can be controlled / regulated.

[0030] The process temperature control system can further include a second heat exchanger. This second heat exchanger can be connected between at least one heat storage tank and the heat generation circuit. In particular, the second heat exchanger can be controlled and / or regulated so that the thermal energy transferred from the heat generation circuit to the heat storage tank can be monitored. For example, the inflow and / or outflow (e.g., flow rate, flow volume, etc.) of the second heat exchanger can be controlled and / or regulated. Thus, the temperature of the storage medium in the heat storage tank can be controlled / regulated.

[0031] In particular, the heat storage unit can be integrated into an intermediate circuit, which uses an intermediate circuit heat transfer fluid. This intermediate circuit heat transfer fluid can differ from the first and / or the second heat transfer fluid. It is also possible that the same heat transfer fluid is used for the first and / or the second heat transfer fluid and / or the intermediate circuit heat transfer fluid.

[0032] When different heat transfer fluids are used, they can be adapted to the specific requirements. For example, a heat transfer fluid with a very high specific heat capacity can be used for heat storage to store as much energy as possible in a small space. For the heat generation circuit and / or the heat consumer circuit, on the other hand, heat transfer fluids with lower viscosity may be advantageous, as they are easier to pump to the heat generator(s) and / or consumers. Furthermore, the boiling points of the heat transfer fluids can be adapted to the respective operating temperatures.

[0033] At least one solar thermal generator can be configured to supply the first heat transfer fluid, at a temperature of at least 250°C (or at least 300°C, or at least 400°C, or at least 450°C, or at least 500°C, or at least 550°C), to the heat storage tank or the second heat exchanger. In this case, the first heat transfer fluid can be an oil or a molten salt whose boiling point is, for example, above the aforementioned temperatures. Water, which is evaporated under pressure in the solar thermal generator, can also be used as the heat transfer fluid.

[0034] The first heat transfer fluid, the second heat transfer fluid and / or the intermediate circuit heat transfer fluid can be selected from one of the following heat transfer fluids: Water, a thermal oil, or a molten salt solution, The first heat transfer fluid, the second heat transfer fluid, and / or the intermediate circuit heat transfer fluid may differ. Typically, heat transfer fluids are in liquid form. However, gaseous (steam) heat transfer fluids can also be used, particularly in the heat generator(s).

[0035] The thermal storage unit can be configured to store a heat transfer fluid at a temperature of at least 180°C, or at least 210°C, and in particular at least 240°C. For example, the thermal storage unit can be configured to store temperatures in the range of 180°C to 560°C, or from 210°C to 500°C, or from 240°C to 400°C. In particular, the temperature of the heat transfer fluid stored in the thermal storage unit depends on the dimensions of the thermal storage unit (e.g., volume, geometric dimensions, insulation, etc.), the type of fluid used, and the type of thermal storage unit. It is understood that the temperature in the thermal storage unit need not be uniformly distributed and, in particular, different temperature ranges may be present.

[0036] In particular, the heat storage system can be a stratified storage system. In such a system, the storage medium is contained in layers with different temperatures, with the temperature decreasing from top to bottom. This type of stratified storage system can thus be connected to the heat consumer circuit at different temperature levels. This allows for the extraction of large amounts of energy when needed.

[0037] The at least one solar heat generator may include a line-concentrating solar heat generator, in particular at least one parabolic trough collector and / or at least one Fresnel collector.

[0038] In parabolic trough collectors, the direct solar radiation is concentrated onto a receiver located at the focus of the parabolic mirror(s) by means of one or more parabolic mirrors.

[0039] In Fresnel collectors, several primary mirrors are aligned to reflect direct solar radiation onto a centrally mounted receiver. To minimize the accuracy requirements of the primary mirrors, a secondary concentrator (for example, a parabolic mirror) can be used to focus the solar rays reflected by the primary mirrors onto the receiver.

[0040] The receiver used in parabolic trough or Fresnel collectors comprises, for example, a tube, such as a steel tube, which may be encased in an evacuated glass tube to minimize heat loss. This tube carries the first heat transfer fluid. The tube may also be coated. This coating ensures high absorption of solar radiation combined with the lowest possible emissivity to further minimize heat loss. The achievable temperature level of the first heat transfer fluid is up to 550 °C, or even higher.

[0041] At least one solar heat generator can be a tracking heat generator, meaning it can follow the sun's position. This can be achieved with a control system that either determines the sun's position itself or receives relevant data. Based on this position, actuators can then be controlled to track the solar heat generator(s). Specifically, at least one solar heat generator can incorporate single-axis tracking.

[0042] In parabolic trough collectors, the parabolic mirror(s) can be tracked uniaxially via a servo motor. This enables high energy yield with less design complexity. In Fresnel collectors, tracking can be achieved via the primary mirrors, which can be adjusted in position. In particular, several primary mirrors can be grouped together and then tracked individually to minimize the control system complexity.

[0043] Furthermore, the process temperature control system can include at least one pump. This pump(s) can be integrated into the process temperature control system to circulate a primary heat transfer fluid, a secondary heat transfer fluid, and / or intermediate circuit heat transfer fluids. By controlling the pump(s), the flow rate of the heat transfer fluids in the respective circuits can be controlled. Thus, the amount of thermal energy transferred can also be controlled.

[0044] In particular, the temperature control device can be configured to mix heat transfer fluid from the supply section with colder heat transfer fluid, for example from the return section, in order to supply the second heat transfer fluid at a defined temperature to the at least one heat transfer fluid outlet. Furthermore, or alternatively, the temperature control device can be configured to control at least one pump of the process temperature control system to control and / or regulate the flow rate of the corresponding heat transfer fluid in the circuit assigned to the pump. By controlling the pump(s), the second heat transfer fluid at a defined temperature can be supplied to the at least one heat transfer fluid outlet.

[0045] For this purpose, at least one controllable pump can be arranged in the heat generation circuit, and / or at least one controllable pump in the intermediate circuit and / or at least one controllable pump in the heat consumer circuit.

[0046] Furthermore, the process temperature control system can include at least one auxiliary heating device. This auxiliary heating device can be assigned to the heat consumer circuit, in particular the flow section and / or the heat storage tank. The auxiliary heating device can compensate for fluctuations, especially naturally occurring fluctuations (day / night, weather, etc.), in solar thermal heat generation and / or raise the temperature level to a required level.

[0047] The auxiliary heating device can be electric or based on other energy sources such as coal, oil, gas, pellets, wood chips, and / or the like. If the auxiliary heating device is, for example, connected to the heat storage unit, it can be an electric heating element that directly heats the corresponding heat transfer fluid.

[0048] Furthermore, the process temperature control system can include at least one supply manifold connected downstream of at least one consumer output. This supply manifold is designed to distribute the second heat transfer fluid to different consumers of a film stretching line. Thus, various consumers, such as extruders, longitudinal stretching units (MDOs), transverse stretching units (TDOs), and / or the like, can be supplied with thermal energy.

[0049] Furthermore, the process temperature control system can include at least one return manifold and a distribution device. The return manifold receives the returning secondary heat transfer fluid from at least one consumer and supplies it to the distribution device. The distribution device is configured to supply the heat transfer fluid to the heat storage tank, the first heat exchanger, and / or the temperature control device. The distribution device can be static. Alternatively, the distribution device can be controlled and / or regulated to control / regulate the corresponding flow rates. Appropriate valves can be provided for this purpose.

[0050] The film stretching system according to the invention, which includes the process temperature control system described above, further comprises at least one of the following components: A drying unit for drying raw materials such as polymer granules and / or polymer powder; a feed hopper, which may be temperature-controlled, for supplying the raw material for film production to an extruder; an extruder, which may be temperature-controlled, that plasticizes the raw material and delivers it as a plastic web or (cast) film to a cooling roller; a blown film line, which may be temperature-controlled, and which is configured to produce a blown film; a cooling roller, which may be temperature-controlled, and which is configured to temperature-control the extruded plastic web (cast film); a longitudinal stretching line, which may be temperature-controlled, and which is configured to stretch an extruded plastic web and / or a blown film longitudinally;A transverse stretching machine, which may be temperature-controlled and which is configured to stretch an extruded plastic web and / or a blown film in the transverse direction; a simultaneous stretching machine, which may be temperature-controlled and which is configured to stretch an extruded plastic web and / or a blown film simultaneously in the longitudinal and transverse directions; a film take-off device, which may be temperature-controlled and which is configured to determine a film thickness and / or to subject the film to a surface treatment; a winding device, which may be temperature-controlled and which is configured to wind the film into rolls; and / or an absorption chiller for process temperature control, in particular for process cooling.

[0051] The film stretching machine is designed so that at least one of its components can be supplied with thermal energy, directly or indirectly, via the process temperature control system to achieve a defined temperature. It is understood that the aforementioned components of the film stretching machine can be temperature-controlled as such, and / or corresponding subassemblies (such as rollers, housings, housing sections, and / or the like) can be temperature-controlled.

[0052] Thus, the film stretching plant, or at least one component (or sub-assembly of the component), can be supplied with solar-generated thermal energy, thereby replacing previously necessary fossil fuels. This leads to an improvement in the CO₂e emission balance of film production.

[0053] Examples of component subassemblies include temperature-controlled rollers, temperature-controlled housings, temperature-controlled housing sections, and the like. These subassemblies can be supplied with heat transfer fluid or thermal energy directly or indirectly.

[0054] In particular, at least one of the components of the film stretching system can be connected to the heat transfer fluid outlet to be supplied directly with heat transfer fluid. With direct supply, the heat transfer fluid can be routed directly from the heat transfer fluid outlet to the respective component (or a subassembly thereof). For example, a roller that guides the film can be cooled by the flow of heat transfer fluid.

[0055] Examples of rollers include the cooling roller, roller(s) assigned to the longitudinal stretching system (such as preheating roller(s), stretching roller(s), annealing roller(s), and / or the like), roller(s) of the film take-off device and / or roller(s) of the winding device.

[0056] Likewise, parts of the drying equipment (in particular a housing part and / or a mixer, ...), the filling hopper, the extruder (in particular a screw and / or a cylinder, or another housing part), housing(s) of the stretching machine(s) and / or the absorption chiller can be directly permeated by tempered heat transfer fluid.

[0057] In indirect supply, the heat transfer fluid is fed to a heat exchanger assigned to the respective component (or subassembly). For example, to temperature-control a housing or housing section of a component (especially longitudinal, transverse, and / or simultaneous stretching systems), the heat transfer fluid can be passed through a heat exchanger that is swept or flowed through with a temperature control medium (such as air). This temperature control medium can then be introduced into the housing or housing section to be temperature-controlled.

[0058] In particular, the film stretching machine can include one or more nozzle boxes, through which air is blown into different temperature zones or housing sections of the stretching machine. Such nozzle boxes are used especially as subassemblies of transverse stretching machines and / or simultaneous stretching machines to achieve the most precise possible temperature control of the film. This nozzle box, at least one of them, can be temperature-controlled by the heat transfer fluid provided by the process temperature control system.

[0059] The film stretching system may further include at least one additional heating device, wherein the additional heating device is designed to supply at least one of the components of the film stretching system with additional thermal energy.

[0060] The auxiliary heating device can compensate for fluctuations in solar thermal heat generation, particularly naturally occurring fluctuations (day / night, weather, etc.), and / or raise the temperature of the respective component to a required level. Furthermore, this auxiliary heating device enables a base temperature level to be maintained via the process temperature control system. If higher temperatures are required for one (or more) components, the auxiliary heating device can provide the additional thermal energy needed to reach and / or maintain the required temperature level.

[0061] The problem is further solved by using the previously described process temperature control system in a previously described film stretching machine, wherein the process temperature control system supplies at least one of the components of the film stretching machine (in particular a subassembly thereof) directly or indirectly with thermal energy in order to control its temperature in a defined manner. Brief description of the characters

[0062] The accompanying figures illustrate aspects of the present invention. In particular, they show Fig. 1 a schematic representation of a process temperature control system with direct heat storage; Fig. 2 a schematic representation of a process temperature control system with direct heat storage; Fig. 3 a schematic representation of a process temperature control system with direct heat storage; Fig. 4 a schematic representation of a process temperature control system with indirect heat storage; Fig. 5 a schematic representation of a film stretching system, and Fig. 6 a schematic representation of a transverse stretching system (TDO). Detailed description of the characters

[0063] In particular, it shows Fig. 1 a schematic representation of a process temperature control system 10 with direct heat storage.

[0064] The process temperature control system 10 comprises a heat generation circuit 100. A solar heat generator 110, in particular a concentrating CSP solar heat generator, such as a parabolic trough collector, is integrated into this heat generation circuit 100. This generator can convert solar radiation energy into usable thermal energy. A first heat transfer fluid 112 is circulated in the heat generation circuit 100 and heated to approximately 550°C, for example, by the solar heat generator 110. A pump 124, which is assigned to the heat generation circuit 100, can circulate the first heat transfer fluid 112 (e.g., water, steam, thermal oil, molten salt, etc.).

[0065] Furthermore, the process temperature control system 10 comprises at least one heat storage unit 210. Thermal energy generated by the at least one solar heat generator 110 can be supplied to the heat storage unit 210 for storage via the heat generation circuit 100. In the embodiment shown here, the heat storage unit 210 contains the first heat transport fluid 112. The storage medium is therefore the first heat transport fluid, so that the thermal energy is stored directly.

[0066] A heat consumer circuit 300, which carries a second heat transfer fluid 312, is connected to the heat storage tank 210 via a heat exchanger 230. This allows thermal energy to be extracted from the heat storage tank 210. The heat exchanger 230 can be operated as described in... Fig. 1The heat exchanger can be located outside the heat storage unit. It is also possible to locate the heat exchanger inside the heat storage unit. The heat exchanger can be, for example, a plate heat exchanger, a tube heat exchanger, and / or the like. This heat exchanger can be operated, for example, in parallel flow, counterflow, or crossflow mode.

[0067] The heat consumer circuit 300 comprises a supply section 320 and a return section 340, wherein the temperature of the second heat transfer fluid 312 is higher in the supply section 320 than in the return section 340. Furthermore, the heat consumer circuit 300 comprises at least one temperature control device 330. This temperature control device 330 has at least one heat transfer fluid output 350, which is connected to a supply distributor 500.

[0068] This supply distributor 500 is designed to supply the second heat transfer fluid 312 to different consumers (components) of a film stretching system 1 (see below). Fig. 5 to distribute the heat. This allows different consumers, such as extruders, longitudinal drawing machines (MDO), transverse drawing machines (TDO), and the like, to be supplied with thermal energy. If only one consumer is to be supplied with heat transfer fluid 312, it can be connected to the heat transfer fluid outlet 350. The supply manifold 500 is therefore optional. Similarly, the return manifold 400 is also optional if, for example, the heat transfer fluid 312 is returned from only one consumer.

[0069] In order to achieve the most accurate temperature control possible, the temperature control device 330 is configured to mix the second heat transfer fluid 312 of the supply section 320 and the second heat transfer fluid 312 of the return section 340 in such a way as to provide the second heat transfer fluid 312 at a defined temperature to the at least one heat transfer fluid output 350.

[0070] The process temperature control system 10 from Fig. 1 The system also includes at least one return manifold 400 and a distribution device 342. The return manifold 400 receives the returning second heat transfer fluid 312 from at least one consumer of the film stretching system and supplies it to the distribution device 342. The distribution device 342 then supplies the returning second heat transfer fluid 312 to the heat exchanger 230. There, it can again absorb thermal energy from the heat storage tank 210 and be directed to the supply section 320.

[0071] In particular, 300 pumps 322, 326 can be provided in the heat consumer circuit to pump or circulate the second heat transfer fluid 312. These can also be controlled or regulated by means of the temperature control device 330.

[0072] Furthermore, the process temperature control system 10 can include at least one auxiliary heating device 324, which is integrated into the heat consumer circuit 300. This allows additional thermal energy to be provided if required. Heat transfer fluid 312 can be directed to the auxiliary heating device 324 via a controllable valve 323 and thus heated additionally. The controllable valve 323 can be a proportional valve, which allows control of the flow rate. In particular, the valve 323 can be controlled or regulated by means of the temperature control device 330.

[0073] Fig. 2Figure 1 shows a schematic representation of another process temperature control system 10 with direct heat storage. This process temperature control system 10 differs from the one in Figure 1. Fig. 1 The process temperature control system 10 shown, in particular in the type of construction of the heat consumer circuit 300.

[0074] The heat consumer circuit 300 of the in Fig. 2 The process temperature control system 10 shown comprises a supply section 320 and a return section 340, wherein the temperature of the second heat transfer fluid 312 is higher in the supply section 320 than in the return section 340.

[0075] Furthermore, the heat consumer circuit 300 includes at least one temperature control device 330. This temperature control device 330 has at least one heat transfer fluid output 350, which is connected to a supply distributor 500.

[0076] This supply distributor 500 is designed to supply the second heat transfer fluid 312 to different consumers (components) of a film stretching system 1 (see below). Fig. 5 to distribute the heat. This allows different consumers, such as extruders, longitudinal drawing machines (MDO), transverse drawing machines (TDO), and the like, to be supplied with thermal energy. If only one consumer is to be supplied with heat transfer fluid 312, it can be connected to the heat transfer fluid outlet 350. The supply manifold 500 is therefore optional. Similarly, the return manifold 400 is also optional if, for example, the heat transfer fluid 312 is returned from only one consumer.

[0077] To achieve the most precise temperature control possible, the temperature control device 330 is configured to mix the second heat transfer fluid 312 of the supply section 320 and the second heat transfer fluid 312 of the return section 340 in such a way as to supply the second heat transfer fluid 312 at a defined temperature to the at least one heat transfer fluid outlet 350. Valves 330a, 330b, and 330c are provided for this purpose.

[0078] Furthermore, the process temperature control system comprises 10 components. Fig. 2at least one return manifold 400. The return manifold 400 receives the returning second heat transfer fluid 312 from at least one consumer of the film stretching system and supplies it, among other things, to valve 330a and valve 330c. Via valve 330c, the returning second heat transfer fluid 312 can be directed to the heat exchanger 230. There, it can again absorb thermal energy from the heat storage tank 210 and be directed to the supply section 320.

[0079] Valves 330a, 330b, and 330c can be controllable valves that can be controlled or regulated by the temperature control device 330. In particular, valves 330a, 330b, and 330c can be proportional valves, which allow control of the flow rate. By selectively controlling valves 330a, 330b, and 330c, the heat transfer fluid 312 can be mixed and supplied to the heat exchanger 210 and / or the heat transfer fluid outlet 350 at a defined temperature.

[0080] In particular, a pump 321 can be provided in the heat consumer circuit 300, which can pump or circulate the second heat transfer fluid 312. Optionally, a pump 222 can also be provided between the heat storage tank 210 and the heat exchanger 230 to pump the corresponding heat transfer fluid. These pumps 321 and 222 can also be controlled or regulated by means of the temperature control device 330.

[0081] Furthermore, the process temperature control system 10 can include at least one auxiliary heating device 324, which is integrated into the heat consumer circuit 300. This allows additional thermal energy to be provided if required. Heat transfer fluid 312 can be directed to the auxiliary heating device 324 via a controllable valve 323 and thus heated additionally. The controllable valve 323 can be a proportional valve, which allows control of the flow rate. In particular, the valve 323 can be controlled or regulated by means of the temperature control device 330.

[0082] Fig. 3 Figure 1 shows a schematic representation of another process temperature control system 10 with direct heat storage. This process temperature control system 10 differs from those described in the Fig. 1 and 2 shown process temperature control systems, in particular in the type of design of the heat consumer circuit 300.

[0083] A pump 222 pumps heat transfer fluid from the heat storage tank 210 to the heat exchanger 230. A pump 331 is connected upstream of the heat exchanger 230. Furthermore, the heat consumer circuit 300 includes several (here, for example, two) auxiliary heating devices 324a, 324b, which are connected in parallel to the heat exchanger 230. A pump 332, 333 is connected upstream of each of the auxiliary heating devices 324a, 324b.

[0084] A return collector 400 receives the returning second heat transfer fluid 312 from at least one consumer of the film stretching system and makes it available to the pumps 331, 332, 333.

[0085] These pumps 222, 331, 332, and 333 can be controlled by the temperature control device 330 to control and / or regulate the flow rate of the corresponding heat transfer fluid in the circuit assigned to the pump. Pump 222 can control / regulate the flow rate of the heat transfer fluid assigned to the heat storage unit 210 in the heat exchanger 230. Pump 331 can control / regulate the flow rate of the heat transfer fluid 312 in the heat exchanger 230. Thus, the amount of thermal energy extracted from the storage unit 210 can be controlled / regulated via pump(s) 222 and / or 331.

[0086] The flow rate of the heat transfer fluid 312 in the auxiliary heaters 324a and 324b can be controlled / regulated via pumps 332 and 333. Thus, the thermal energy transferred to the heat transfer fluid 312 can also be controlled / regulated here.

[0087] After the heat transfer fluid 312 has passed through the circuits of the auxiliary heater(s) 324a, 324b and / or the heat exchanger 230, the circuits are mixed and fed to the heat transfer fluid outlet 350 or the supply manifold 500. As explained above, the supply manifold 500 is optional and can be omitted if only one consumer is to be supplied with heat transfer fluid 312. Similarly, the return manifold 400 is also optional if, for example, the heat transfer fluid 312 is returned by only one consumer.

[0088] Fig. 4 Figure 1 shows a schematic representation of a process temperature control system 10 with indirect heat storage. This process temperature control system 10 differs from the one described in Figure 1. Fig. 1 The process temperature control system 10 shown is particularly interesting in the way the heat storage unit 210 is integrated into the process temperature control system 10. In the Fig. 4In the system shown, the first heat transfer fluid 212 is not fed directly into the heat storage unit 210, but rather through a heat exchanger 215. This heat exchanger 215 is integrated into an intermediate circuit 200, which also includes the heat storage unit 210. The intermediate circuit 200 carries an intermediate circuit heat transfer fluid 212. This intermediate circuit heat transfer fluid 212 can differ from the first heat transfer fluid 112 and / or the second heat transfer fluid 312.

[0089] The energy generated by the solar heat generator 110 is first transferred to the first heat transport fluid 112 (in the solar heat generator 110) and then transferred in the heat exchanger 215 to the intermediate circuit heat transport fluid 212 for storage in the heat storage tank 210 (indirect storage).

[0090] Fig. 5Figure 1 shows a schematic representation, in a highly simplified form, of a film stretching machine 1, which is set up for the biaxial stretching of film 9. This film stretching machine 1 comprises several components that represent the individual process steps of film production. In particular, the film stretching machine 1 is set up for the sequential biaxial stretching of film 9.

[0091] First, the starting material to be processed, i.e. a polymer (granules and / or powder), is supplied via a dosing system comprising a filling hopper 2 to an extruder 3 and melted in the extruder 3.

[0092] The polymer melt is applied to a cooling roller 4 and cooled by means of a nozzle unit 3a (for example, a slot die) which is connected downstream of the extruder(s) 3. The resulting film 9 is then stretched lengthwise in the machine direction by means of a longitudinal stretching unit (MDO) 5. Depending on the material and process, this longitudinal stretching takes place in a temperature range of approximately 80°C to approximately 140°C.

[0093] The film is then inserted into a transverse stretching device (TDO) 6 and stretched transversely. The stretching is carried out with reference to Fig. 6This process is described in more detail below. Depending on the material and process, this transverse stretching takes place within a temperature range of approximately 80°C to 200°C, with the temperature range for stretching being material-dependent. For PA, PET, and PP films, this temperature range is approximately 80°C to 200°C. The oven of the transverse stretching device (TDO) can be operated at a higher temperature, for example, in a range of 80°C to 240°C.

[0094] The film 9 is then pulled out of the oven by means of a downstream film pull-off device 7 (so-called pull roll) and subsequently wound up by means of the winding device 8.

[0095] Similarly, stretching can be performed simultaneously rather than sequentially. The difference between simultaneous and sequential stretching lies in the simultaneous stretching of the films in both longitudinal and transverse directions (MD and TD directions). This is achieved in a so-called simultaneous stretching system (e.g., a simultaneous stretching oven). The simultaneous stretching system heats and accelerates a clamped film in such a way that it is stretched simultaneously in both the longitudinal and transverse directions. Consequently, a separate longitudinal stretching system is not necessary.

[0096] By means of a previously described process temperature control system 10 (see Fig. 1 , 2 , 3 or 4The individual components (for example, the feed hopper 2, the extruder 3, the cooling roller 4, the longitudinal stretching unit (MDO) 5, the transverse stretching unit (TDO) 6, the film take-off device 7 and / or the winding device 8) can be temperature-controlled. This allows solar energy to be used for film production and reduces the use of fossil fuels.

[0097] The following example illustrates this. Consider a solar thermal system comprising linear Fresnel collectors. With a solar thermal system size of 5000 m², an average DNI (Direct Normal Irradiance) of 340 W / m² results in approximately 3,520 MWh of thermal energy at a heat transfer fluid temperature of approximately 250 °C. Given a total annual thermal demand of about 15,000 MWh for the TDO and MDO systems, currently supplied by coal, this corresponds to 23% or 1.471 tCO₂e.

[0098] As the above example shows, the use of concentrated solar thermal energy offers high energy saving potential in heat generation for a film stretching plant.

[0099] Fig. 6 Figure 1 shows a schematic representation of a transverse stretching machine (TDO). It is also conceivable that the stretching machine is a simultaneous stretching machine. The transverse stretching machine 6 comprises a furnace 612, a transport system 614, and a compensating device 616.

[0100] Oven 612 has a discharge direction R, which corresponds to the direction of movement of the film 9 to be stretched. Perpendicular to the discharge direction R and horizontally runs the transverse direction Q of oven 612, and vertically the vertical direction H.

[0101] The oven 612 has different zones along the extraction direction R for treating the film 9 to be stretched.

[0102] In the first zone 622, also called the preheating zone, the film is heated. In the subsequent second zone 624 ("stretching zone"), the film is stretched in the transverse direction Q, so that at the end of the second zone 624 it has a greater width than at the beginning.

[0103] After stretching, the film 9 then passes through the third zone 626 ("heat treatment zone", "further heating zone" and / or "annealing zone"), where relaxation of the film 9 can take place at high temperatures.

[0104] The film 9 then passes through a fourth zone 628 and a fifth zone 630 ("cooling zone"), where the film is cooled in the fifth zone 630.

[0105] The fourth zone, 628, is called the neutral zone and serves to separate the third zone, 626, and the fifth zone, 630. The neutral zone is, for example, an empty room without ventilation.

[0106] The transport system 614 comprises, in a manner known per se, two transport rails 632 which are arranged symmetrically with respect to a central plane M of the stretching system 6 or of the furnace 612 and which extend at least partially into the furnace 612.

[0107] In an inlet zone 634 and an outlet zone 636, in which the film to be stretched is fed into and out of the stretching system 6, the transport rails 632 run outside the oven 612.

[0108] The film 9 is gripped in a manner known per se by clamps (not shown) of the transport system 614, which are guided along the transport rails 632, and transported through the oven 612 in the discharge direction R. The film runs in a film track F which is defined in the oven 612 by the transport system 614. The film track F intersects the median plane M.

[0109] In particular, zones 634, 622, 624, 626, 628, 630 and 636 of the furnace 612 can be temperature-controlled using the process temperature control system 10.

[0110] Furthermore, several nozzle boxes (not shown) are arranged in the oven 612, which convey hot (tempered) air towards the film web F. The hot air is used to heat, cool, or maintain the interior of the oven, and thus the film 9, at a predetermined temperature. The air can be tempered via suitable heat exchangers of the transverse stretching system using the process temperature control system 10. Reference symbol list

[0111] 1 Film stretching machine 2 Feed hopper 3 Extruder 4 Cooling roller 5 Longitudinal stretching machine (MDO) 6 Transverse stretching machine (TDO) 7 Film take-off device 8 Winding device 9 Film 10 Process temperature control system 100 Heat generation circuit 110 Solar heat generator 112 First heat transfer fluid 124 Pump 200 Intermediate circuit 210 Heat storage (buffer storage) 212 Intermediate circuit heat transfer fluid 215 Heat exchanger (generator side) 222 Pump 230 Heat exchanger (consumer side) 300 Heat consumer circuit 312 Second heat transfer fluid 320 Flow section 322 Pump 321 Pump 323 Valve (for auxiliary heating) 324 Auxiliary heating device 324a Auxiliary heating device 324b Auxiliary heating device 326 Pump 330 Temperature control device 330a Valve 330b Valve 330c Valve 331 Pump 332 Pump 333 Pump 340 Return section 342 Distribution device 350 Heat transfer fluid outlet 400 Return manifold 500 Flow distributor 612 Oven 614 Transport system 616 Compensation device 622 Preheating zone 624 Stretching zone 626 Heat treatment zone, reheating zone and / or annealing zone 628 Neutral zone 630 Cooling zone 632 Transport rail 634 Infeed zone 636 Outfeed zone H Upward direction of the furnace 612 Q Transverse direction of the furnace 612 R Extraction direction M Middle plane of the transverse stretching system

Claims

1. A film stretching unit (1) comprising a process temperature control system (10), as well as at least one of the following components: a drying apparatus, a feed hopper (2), an extruder (3), a blown film unit, a chill roll (4), a machine direction orienter (5), a transverse direction orienter (6), a simultaneous stretching unit, a pull-roll device (7), a wrapping device (8), and / or an absorption cooling machine, wherein the film stretching unit (1) is configured in such a way that at least one of the components is supplied with thermal energy directly or indirectly by means of the process temperature control system (10) in order to be temperature-controlled in a defined manner, and wherein the solar-thermal process temperature control system (10) comprises at least one solar heat generator (110), which is integrated into a heat generation circuit (100), wherein the heat generation circuit (100) conveys a first heat transfer fluid; at least one heat storage unit (210), to which thermal energy is supplied via the first heat generation circuit (100), said thermal energy having been generated by said at least one solar heat generator (110), wherein the heat storage unit (210) is configured to store the thermal energy; at least one heat consumer circuit (300), which conveys a second heat transfer fluid (312), wherein the heat consumer circuit (300) is connected to the heat storage unit (210) in order to be capable of drawing stored thermal energy, at least one temperature control device (330), wherein said at least one temperature control device (330) comprises at least one heat transfer fluid outlet (350) and is configured to supply the second heat transfer fluid at a defined temperature to said at least one heat transfer fluid outlet (350) in order to supply at least one component of a film stretching unit (1) directly or indirectly with defined temperature-controlled heat transfer fluid.

2. The film stretching unit (1) according to claim 1, wherein the process temperature control system (10) further comprises a first heat exchanger (230) that is connected between said at least one heat storage unit (210) and the heat consumer circuit (300).

3. The film stretching unit (1) according to any of the preceding claims, wherein the process temperature control system (10) further comprises a second heat exchanger (215) that is connected between said at least one heat storage unit (210) and the heat generation circuit (100).

4. The film stretching unit (1) according to claim 2 and 3, wherein the heat storage unit (210) is integrated into an intermediate circuit (200) that conveys an intermediate-circuit heat transfer fluid (212).

5. The film stretching unit (1) according to any of the preceding claims, wherein said at least one solar heat generator (110) is configured to supply the first heat transfer fluid (112) at a temperature of at least 550°C to the heat storage unit (210) or the second heat exchanger (215).

6. The film stretching unit (1) according to any of the preceding claims, wherein the first heat transfer fluid (112), the second heat transfer fluid (312) and / or the intermediate-circuit heat transfer fluid (212) is selected from the following heat transfer fluids: water, a thermal oil, or a molten salt, wherein the first heat transfer fluid (112), the second heat transfer fluid (312) and / or the intermediate-circuit heat transfer fluid (212) may differ.

7. The film stretching unit (1) according to any of the preceding claims, wherein said at least one heat storage unit (210) is configured to store a heat transfer fluid at a temperature of at least 180°C, or at least 210°C and in particular at least 240°C.

8. The film stretching unit (1) according to any of the preceding claims, wherein said at least one solar heat generator (110) comprises a linear concentrating solar power generator, in particular at least one parabolic trough collector and / or at least one Fresnel collector.

9. The film stretching unit (1) according to any of the preceding claims, wherein said at least one solar heat generator (110) is a tracking heating generator that comprises at least one single-axis tracking.

10. The film stretching unit (1) according to any of the preceding claims, wherein the process temperature control system (10) a further comprises at least one pump (124, 322, 326), which is integrated into the process temperature control system (10) in such a way to circulate the first heat transfer fluid (112), second heat transfer fluid (312) and / or intermediate-circuit heat transfer fluid (212).

11. The film stretching unit (1) according to any of the preceding claims, wherein the heat consumer circuit (300) comprises a supply section (320) and a return section (340), wherein the temperature control device (330) is configured to mix heat transfer fluid of the supply section (320) with colder heat transfer fluid, for example from the return section (340), in order to supply the second heat transfer fluid at a defined temperature to said at least one heat transfer fluid outlet (350), and / or wherein the temperature control device (330) is configured to activate at least one pump (124, 322, 326, 331, 332, 333) of the process temperature control system in order to control the flow velocity of the corresponding heat transfer fluid in the circuit allocated to the pump in order to supply the second heat transfer fluid at a defined temperature to said at least one heat transfer fluid outlet (350).

12. The film stretching unit (1) according to any of the preceding claims, wherein the process temperature control system (10) further comprises at least one additional heating device (324), wherein said at least one additional heating device (324) is allocated to the heat consumer circuit (300), in particular the supply section (320), and / or the heat storage unit (210).

13. The film stretching unit (1) according to any of the preceding claims, wherein the process temperature control system (10) further comprises at least one supply manifold (500) that is connected downstream of the heat transfer fluid outlet (350) and is configured to distribute the second heat transfer fluid to different consumers of the film stretching unit (1).

14. The film stretching unit (1) according to any of the preceding claims, wherein the process temperature control system (10) further comprises at least one return collector (400) and a distributing device (342), wherein the return collector (400) takes the second heat transfer fluid from at least one consumer and supplies it to the distributing device (342), wherein the distributing device (342) is configured to supply the heat transfer fluid to the heat storage unit (210), the first heat exchanger (230) and / or the temperature control device (330).

15. The Film stretching unit (1) according to any one of claims 1 to 14, wherein at least one of the components is connected to the heat transport fluid outlet (350) to be supplied directly with heat transfer fluid.

16. Film stretching unit (1) according one of the claims 1 or 15, further comprising at least one additional heating device, wherein the additional heating device is configured to supply at least one of the components (2, 3, 4, 5, 6, 7, 8) of the film stretching unit (1) with additional thermal energy.