Fresh air heat exchanger and method for providing heated fresh air with electrically heated fresh air heat exchanger

Abstract

The invention relates to a fresh air heat exchanger (100) for heating a flow of fresh air, comprising: at least one ventilator (106) for drawing in fresh air and generating a flow of fresh air; and at least one electrically heated heat transfer unit (108) for transferring heat energy to the fresh air flow.

Description

Technical Field

[0001] The invention relates to a fresh air heat exchanger and a method for providing heated fresh air with a corresponding fresh air heat exchanger. Background Art

[0002] It is known from practice to use fresh air heaters within workpiece processing plants, in particular drying plants for vehicle bodies (referred to as dryers for short), which heat the fresh air supplied to the lock region of such plants in order to avoid condensation, in particular in the lock region of the plants.

[0003] In general, the following two possibilities are known for heating with fresh air heaters of this type.

[0004] On the one hand, in a dryer with a waste heat recovery (TAR) hot exhaust gas purification unit, the clean gas enthalpy flow can be used for fresh air warming near the dryer, that is, the heat energy of the clean gas guided from the TAR is transferred to the fresh air supplied to the dryer.

[0005] On the other hand, in the case of burner heating, the fresh air heating can be carried out directly, for example by means of a plate gas burner. It can be carried out directly or indirectly by means of a combustion chamber with a flue gas heat exchanger.

[0006] Therefore, corresponding fresh air heaters are known which comprise the following components: a suction section with a filter, in which suction takes place, for example, directly from the dryer workshop; a sound damping section; a heat exchanger for transferring the thermal energy of the clean gas to the supplied fresh air, or a combustion chamber for burning the burner gas using the supplied fresh air; a ventilator; and the necessary fresh air and clean gas channels.

[0007] In this case, the fresh air heater can be integrated into the housing or be designed separately, wherein in the latter embodiment the individual components are connected by means of a channel system.

[0008] Fresh air heaters of this type can be arranged on a separate steel structure platform above the dryer on the one hand. In rare cases, they can also be arranged below the dryer, wherein the dryer pipe itself is therefore supported on the steel structure.

[0009] On the other hand, in the case of clean gas heating, a fresh air heater can be arranged at the beginning or end of the clean gas passage (Reingasstrang), i.e. at the beginning or end of the dryer, especially before the clean gas is discharged to the atmosphere, i.e. preferably before it is led out of the workshop through the roof, and the temperature of the clean gas is reduced to a low temperature level by means of the supplied fresh air. In order to reduce the temperature of the clean gas by the supplied fresh air, a countercurrent heat exchanger is preferably used.

[0010] In burner-heated dryers, the exhaust gas is usually purified in a gas-driven regenerative hot exhaust gas purification system, which is also called regenerative thermal oxidation (RTO). However, due to the design of this type of system, which generally has three chambers and the dimensions associated therewith, it is conceived to be set up outside a building, i.e. a workshop. Therefore, due to the required channel length between the RTO and the fresh air heat exchanger, waste heat utilization is not used in most cases to preheat the fresh air supply.

[0011] Furthermore, compact designs are not feasible due to the bulky clean gas heat exchanger or the bulky combustion chamber.

[0012] Furthermore, corresponding devices require two separate ducts or duct systems for heating medium and fresh air.

[0013] Furthermore, there are also restrictions on the installation possibilities. Therefore, the arrangement above the dryer requires an additional steel structure platform. In particular, if two locks (inflow and outflow) must be attached from the fresh air heat exchanger, an isolated fresh air duct is always additionally required over at least twice the entire dryer length, regardless of the installation location.

[0014] As mentioned above, fresh air heated in the fresh air heater is supplied to the dryer, specifically on the one hand to the lock area of ​​the dryer and on the other hand to the circulating air assembly or circulating air module of the section of the dryer in which the workpieces are treated or dried.

[0015] The dryer generally has an inlet lock at the (end-side) inlet of the dryer and an outlet lock at the (end-side) outlet of the dryer, wherein the dryer generally comprises a plurality of sections arranged in sequence, which together form a treatment channel. In addition, intermediate locks may also be arranged between the treatment sections of the dryer.

[0016] The inflow lock, the intermediate lock, and the outflow lock may be configured as a single stage, or alternatively, the inflow lock and the outflow lock may be configured as a two-stage lock.

[0017] In the case of single-stage locks, a constant fresh air volume flow is accordingly conducted into these locks by means of a duct starting from the fresh air heater.

[0018] Furthermore, a variable fresh air volume flow is conducted into the circulating air components by means of further channels leading to the individual circulating air components and corresponding branch lines.

[0019] In this case, the fresh air control flap is used to adjust the fresh air quantity in such a way that a variable fresh air portion is supplied to the circulating air component as a function of the dryer load rate, while a constant fresh air portion is always supplied to the damper. This is because at low dryer load rates, for example in a paint dryer, less solvent escapes from the painted surface of the workpiece to be dried. Accordingly, the total fresh air quantity fed into the dryer or the variable portion supplied to the circulating air component can also be smaller.

[0020] In the case of a two-stage inflow lock and / or outflow lock, i.e. a lock with a line-based (silhouettenbasierten) double air curtain at the end side of the dryer, the outer air curtain or outer stage is respectively supplied with fresh air heated in a fresh air heater via its own channel (fresh air curtain), while the inner air curtain or inner stage is respectively supplied with circulating air from an adjacent circulating air component (circulating air curtain). Adjacent here means that the inner stage of the outflow lock is supplied with circulating air from the last treatment section of the dryer, i.e. the last holding zone, or the inner stage of the inflow lock is supplied with circulating air from the first treatment section of the dryer, i.e. the first heating zone.

[0021] In other words, the fresh air curtain can be regarded as a barrier which adjoins the cooler area on its outwardly directed side. Thus, the fresh air curtain of the inlet lock preferably forms a barrier between the environment of the process chamber and the circulating air curtain of the inlet lock, while the fresh air curtain of the outlet lock preferably forms a barrier between the cooling zone located behind the process chamber and the circulating air curtain of the outlet lock.

[0022] Within the framework of the proposed fresh air / exhaust air concept, in the case of a two-stage damper, the inner stage, i.e. the corresponding circulating air curtain, is not directly influenced by the flap adjustment, i.e. the supplied circulating air portion remains constant. Therefore, the air portion is adapted only for the fresh air supplied by the fresh air heater, wherein the portion for the outer stage, i.e. the fresh air curtain, remains constant, while the portion for the circulating air component is adapted or can be adapted depending on the load rate of the dryer via the assigned regulating flap.

[0023] A disadvantage of the previous variable fresh air / exhaust air control is that, in the case of clean gas and burner heating, this approach requires two separate fresh air channels, specifically a sluice channel for a constant fresh air portion and a separate component channel for a variable fresh air portion. These channels must be led to the other end of the dryer, generally to the inlet sluice. In the case of a 30 jph dryer, this corresponds to a channel length of 15 vehicle lengths, and in the case of a 60 jph dryer, this corresponds to a channel length of 30 vehicle lengths.

[0024] Furthermore, by supplying the circulating air component with a variable fresh air portion, the fresh air portion does not contribute to reducing the solvent concentration in the lock region and therefore does not minimize the risk of its condensation in cold edge regions of the dryer, such as the inflow region or the cooling zone. Summary of the invention

[0025] It is therefore an object of the present invention to provide a fresh air heat exchanger for heating a fresh air flow which allows a more flexible and economical arrangement on the dryer plane by means of a more compact design.

[0026] According to the invention, this object is achieved by providing a fresh air heat exchanger for heating a fresh air flow, comprising:

[0027] at least one ventilator for drawing in fresh air and generating a fresh air flow, and

[0028] - At least one electrically heated heat transfer unit for transferring thermal energy to the fresh air flow.

[0029] Advantageously, the fresh air to be heated is preheated in a preheating device before being supplied.

[0030] This approach is particularly economical and sustainable if waste heat from the dryer or regenerative energy is used for this purpose, since the requirement for electrical current with high energy quality (useful energy) can be reduced in this way.

[0031] On the one hand, this can also be achieved by means of an electrical and thus flameless device for regenerative thermal oxidation of the dryer exhaust gas. In contrast to gas-heated RTOs (see above), electrical RTOs can be set up inside a building due to their type of construction (single bed) and thus in the vicinity of the dryer. This makes it possible to carry out fresh air preheating following the electrical RTO with the aid of the clean gas enthalpy flow. The electrical RTO is characterized by a low temperature increase of about 20 K during the thermal oxidation process. The enthalpy flow of the clean gas is generally not sufficient to bring the fresh air to the desired rated temperature solely with the aid of a heat exchanger which transfers the thermal energy of the clean gas to the fresh air. On the other hand, the combination of preheating of the fresh air and the subsequent electrical temperature increase which occurs in the fresh air heat exchanger according to the invention makes it possible to achieve the rated temperature efficiently.

[0032] On the other hand, the heat pump can be used to preheat the fresh air. In this form of preheating, small amounts of waste heat that cannot be used further (e.g., cooling zone exhaust air with a temperature in the range of 40°C to 50°C or residual clean gas enthalpy flow after RTO with a temperature between 60°C and 100°C) are brought to a temperature level that can be used to preheat the fresh air using mechanical drive energy. For example, the heat exchange between the heat pump and the fresh air or clean gas can be carried out via a water-air heat exchanger.

[0033] However, it is also conceivable to carry out direct evaporation of heat absorption on the evaporator side or direct condensation of heat removal on the condenser side by supplying heat energy to the working gas or removing heat energy therefrom via a heat exchanger and thus without an intermediate medium.

[0034] In addition, solar thermal energy can be used for preheating, for example by exchanging heat between fresh air and a solar heat transfer medium (eg thermal oil or water) via a water-air heat exchanger or an oil-air heat exchanger.

[0035] The fresh air heat exchanger according to the invention has the advantage that, due to the omission of the heating medium, a simplified channel arrangement can be achieved inside the treatment plant or inside the dryer, since only the channel wiring for the fresh air has to be carried out. In addition, a reduction in the depth and length of the entire heat exchanger can be achieved compared to a clean gas heat exchanger with a combustion chamber concept. The compact design advantageously allows integrated installation in a circulating air component or a lock or a lock module. In addition, previously unused gaps, for example between the dryer outer wall and the dryer inner wall (useful space wall), can be used to arrange the fresh air heat exchanger according to the invention.

[0036] Unlike the prior art, the compact design of the fresh air heat exchanger allows it to be arranged in the pipeline plane, ie in the plane of the process section of the dryer, preferably in a sandwich between two circulating air components. Therefore, no additional steel structure is required.

[0037] Since the fresh air heat exchanger according to the invention no longer has to be set up at the end of the clean gas passage, it is advantageously possible to split the heat exchanger, i.e. separate fresh air heat exchangers for the inflow lock and outflow lock. Thus, preferably no isolated fresh air channel over the entire length of the dryer is required.

[0038] In the case of an intermediate lock, the inlet lock or outlet lock assembly can also be supplied with electrically heated fresh air from a fresh air heat exchanger. In this case, the temperature of the fresh air heated in the fresh air heat exchanger is adjusted according to the intermediate lock, the heated fresh air flow is diverted, and correspondingly the cold fresh air for the inlet lock is mixed into the heated fresh air flow.

[0039] It is further provided that at least one electrically heated heat transfer unit comprises at least one heating resistor arrangement.

[0040] The electrically heated heat transfer unit, which is also referred to as a register, preferably comprises a heating rod as a heating resistor, which has a profiled tube surrounding the heating wire. This results in low dirt adhesion and at the same time good cleaning possibilities.

[0041] Alternatively, an open electrically isolated coil with high temperature resistance can be used. The fresh air flow flows directly over the heating wire in this case; in this way, a maximum heat transfer efficiency is achieved. Compared to heating rods with shaped tubes, this alternative is a cost-effective variant.

[0042] In one embodiment of the invention, it is provided that at least one electrically heated heat exchange unit is arranged downstream of at least one ventilator.

[0043] Furthermore, it can be provided that the fresh air heat exchanger has at least one filter unit for filtering the drawn-in fresh air.

[0044] Since the fresh air is sucked from, for example, a room around the dryer, filtering the sucked fresh air is beneficial to prevent impurities, especially the heating resistor mechanism. It is sufficient to filter here, because the sucked fresh air has not yet come into contact with the dryer atmosphere.

[0045] In a further embodiment of the invention, it is provided that the fresh air heat exchanger has at least one sound damping unit for reducing the sound emission of the fresh air flow.

[0046] In a further embodiment of the invention, it is provided that at least one filter unit and / or at least one sound damping unit is arranged upstream of at least one fan.

[0047] In a further embodiment of the invention, it is provided that at least one filter unit and / or at least one sound damping unit can be arranged at least partially above at least one fan.

[0048] In a further embodiment of the invention, it is provided that the fresh air heat exchanger has at least two, preferably three, electrically heated heat transfer units.

[0049] In another embodiment of the invention, it is provided that the electrically heated heat transfer units are arranged one behind the other along the fresh air flow.

[0050] As a result, the fresh air flow can be gradually heated in order to reach the target temperature at the latest when it passes through the last heat exchange unit.

[0051] In a further embodiment of the invention, it is provided that a first flow path of the fresh air flow upstream of the fan is perpendicular to a second flow path of the fresh air flow downstream of the fan.

[0052] The fresh air guide is on the suction side of the ventilator, i.e. upstream of the ventilator, for sucking fresh air through the filter unit and through the subsequent sound damping unit, and can be referred to as a first flow path, which forms a U-shape from the filter unit via the sound damping unit to the ventilator. The fresh air flow extends horizontally from the suction section via the filter unit to the sound damping unit with reference to the setting plane of the dryer. Next, the air flow extends vertically through the sound damping unit before it subsequently flows into the ventilator as a horizontal air flow.

[0053] The fresh air guide is preferably guided in the technical direction of conveying or conveying direction of the workpieces or against the technical direction of conveying or conveying direction of the workpieces when it is set up on the pressure side of the ventilator, i.e. downstream of the ventilator, in the longitudinal direction of the housing and thus between two circulating air components on the dryer duct plane. The flow direction downstream of the ventilator can be regarded as a second flow path. Here, the fresh air preferably flows straightly and parallel to the plane in which the dryer is set up through the heat transfer unit, i.e. the fresh air does not turn back and forth as in the case of a cross-counterflow heat exchanger. Therefore, no turning space is required, which may require additional installation space perpendicular to the air guiding direction.

[0054] The first and second flow paths or the planes of the flow paths are preferably perpendicular to each other.

[0055] It is further preferred that the second flow path extends at least approximately along a conveying direction of the treatment device or the treatment chamber or counter to the conveying direction of the treatment device or the treatment chamber.

[0056] In a further embodiment of the invention, it is provided that at least one fan is a radial fan.

[0057] The radial fan converts the fresh air flow on the upstream side into a fresh air flow on the downstream side perpendicular to the former with respect to its flow direction. Therefore, the radial compressor causes the first flow path to extend perpendicularly to the second flow path.

[0058] In a further embodiment of the invention, it is provided that the fresh air heat exchanger comprises a housing in which at least one filter unit, at least one sound damping unit, at least one ventilator and at least one electrically heated heat transfer unit are at least partially accommodated.

[0059] In a further embodiment of the invention, it is provided that the housing comprises a service side which has at least one maintenance access.

[0060] The object is also achieved by the use of a fresh air heat exchanger according to the invention as described above for heating a fresh air flow which is supplied to a treatment device for workpieces, in particular a drying device for vehicle bodies.

[0061] According to the invention, the object is further achieved by a method for providing heated fresh air with an electrically heated fresh air heat exchanger, wherein the method comprises the following steps:

[0062] - extract fresh air from the environment in a fresh air heat exchanger,

[0063] - Filter the fresh air that is drawn in,

[0064] - reduce the sound emission of the sucked fresh air,

[0065] - deflecting the flow direction of the fresh air flow and compressing the fresh air flow,

[0066] - transferring the thermal energy generated by at least one heating resistor means to the fresh air flow, and

[0067] - Exhaust heated fresh air.

[0068] Fresh air is drawn in from the fresh air heat exchanger by the fan and is purified of impurities from the ambient air on the inlet side while flowing through at least one filter unit.

[0069] The sound emission is then reduced within the sound damping unit.

[0070] The fresh air flow is then led through a fan, preferably a radial fan, which compresses the fresh air flow and deflects it in a direction perpendicular to the upstream direction of the fresh air flow.

[0071] Thereafter, the fresh air flow flows around at least one electrically heated heat exchange unit, each of which has a heating resistor.

[0072] Finally, the heated fresh air is discharged from the fresh air heat exchanger in the direction of the lock of the dryer.

[0073] In another embodiment of the invention, it can be provided that the method according to the invention includes a step of preheating the fresh air in a preheating device, wherein the preheating device is a heat pump, a regenerative thermal, in particular purely electrically driven and flameless oxidation device, or a solar thermal energy device including thermal oil or water.

[0074] The heated fresh air is then used in a treatment installation for workpieces, in particular a drying installation for vehicle bodies, or is provided with heated fresh air, whereby the locks of the treatment installation can be supplied with heated fresh air.

[0075] A corresponding processing device for processing workpieces, in particular vehicle bodies, comprises a processing chamber, which in turn comprises a plurality of processing chamber sections, each of which is assigned to one of a plurality of individual circulating air modules of the processing device, and at least one lock. The lock can have a first stage and a second stage, wherein fresh air can be supplied to the first stage of the lock, and wherein circulating air and / or fresh air can be supplied to the second stage.

[0076] It is provided that the treatment plant further comprises at least one electrically heated fresh air heat exchanger according to the invention, which supplies heated fresh air to at least one lock.

[0077] The use of a fresh air heat exchanger enables the use of separate fresh air heat exchangers for the inlet and outlet locks, wherein the heat exchanger provides a constant fresh air quantity for the first stage (fresh air curtain or line) or a variable fresh air quantity for the corresponding second stage (circulation air line or circulation air and fresh air line).

[0078] Advantageously, in particular in the case of these two-stage locks, the lock air, which is constant over the entire dryer length, does not require a separate fresh air channel. Likewise, the air to the circulating air assembly, which is variable over the entire dryer length, no longer requires a separate fresh air channel, since all fresh air is now used in the area of ​​the lock.

[0079] Furthermore, it is conceivable to arrange at least one adjustable and / or controllable throttle element between the electrically heated fresh air heat exchanger and the first stage of the at least one lock, so that a constant volume flow of fresh air can be supplied to the first stage of the lock.

[0080] Furthermore, at least one further adjustable and / or controllable throttle element may be arranged between the process chamber segment and the at least one second stage of the lock, so that a constant volume flow of circulating air and / or fresh air can be supplied to the second stage of the lock.

[0081] Therefore, the first throttle associated with the first stage ensures the volume flow to the first stage by releasing the excess fresh air portion into the passage or guide of the second stage. The total volume flow to the second stage is adjusted via the other, second throttle, so that the second stage is also supplied with a constant volume flow.

[0082] It can further be provided that the second stage of at least one damper is associated with a damper fan. The damper fan preferably comprises a frequency converter or is frequency-regulated and / or controlled.

[0083] Furthermore, it is possible to supply the second stage of the lock with 50%, preferably 100%, particularly preferably 200% more recirculated air than fresh air.

[0084] It can also be provided that the first stage and the second stage of the lock are each associated with a filter unit.

[0085] It is also conceivable that at least one temperature sensor and at least one volume flow sensor are arranged between the at least one electrically heated fresh air heat exchanger and the at least one damper and between the at least one circulating air module and the at least one damper, respectively.

[0086] Furthermore, the second stage of the damper can be associated with a pressure sensor for regulating the damper fan.

[0087] It can also be provided that the first and second stages of the lock comprise slot nozzles for forming a line-based air curtain.

[0088] In the event of an inflow to the lock, the fan of the fresh air heat exchanger according to the invention can therefore supply fresh air to the fresh air line of the first stage of the lock.

[0089] Furthermore, the dedicated lock fan also supplies the circulation air line of the second stage of the lock with circulation air from the adjacent treatment chamber section or the adjacent heating / drying zone.

[0090] The fresh air duct and the circulating air duct are connected to one another via a branch.

[0091] The converging point of the two air ducts opens onto the suction side of the sluice fan. In this way, the sluice fan can be supplied with both fresh air and circulating air.

[0092] Motor-driven throttling mechanisms are arranged in the two supply sections of the lock fan, namely on the suction side for fresh air and circulating air, by means of which, on the one hand, the air volume proportions of fresh air and circulating air can be adjusted according to the lock level, and on the other hand, undesirable flow reversals of the lock air (fresh air lock and circulating air lock) can be prevented.

[0093] The speed of the fan of the fresh air heat exchanger according to the invention and the fresh air quantity delivered thereby depends on the volume flow required for the drying process in the dryer. Since the air quantity of both lock stages must be kept constant in each operating state in order to achieve an optimal lock function, the excess fresh air quantity of the first stage is supplied to the second lock stage, i.e. the circulating air stage, via a branch of the fresh air supply.

[0094] For this purpose, a volume flow probe and a temperature sensor are arranged or installed in the fresh air supply, with the help of which a standard volume flow is calculated. The calculated value is used as a regulating value for the motor-driven throttle mechanism. It is adjusted so that the fresh air flow to the first gate stage is always constant, while the excess fresh air flow can be used for the second gate stage.

[0095] The damper fan uses the signal of the pressure sensor assigned to it to ensure a constant volume flow of the second damper stage. The motor-driven throttle mechanism is adjusted so that the excess fresh air flow together with the circulating air flow results in a constant volume flow for the second damper stage.

[0096] Optionally, the sluice fan can be equipped with a frequency regulator. In this case, the volume flow can be kept constant by means of a speed variation of the fan and by means of a motor-driven throttle mechanism or preferably even without a motor-driven throttle mechanism.

[0097] Preferably, all electrically driven heating components, such as fresh air heat exchangers, can be supplied with, for example, an average voltage of at least about 3 kV and / or at most about 8 kV, in particular 4160 V to 6600 V instead of the usual 400 V. This may require special heating elements with corresponding additional costs, but preferably provides a huge saving potential in external equipment related to wiring parts, cables, etc. In addition, a significantly lower voltage conversion factor from the power supply network is necessary, which also makes the substation smaller and saves space in a way that is conducive to saving investment costs. The connection with electrically driven heating components with this type of average voltage also significantly reduces the cable diameter. BRIEF DESCRIPTION OF THE DRAWINGS

[0098] Further preferred features and / or advantages of the invention are the subject matter of the following description of exemplary embodiments and of the drawings.

[0099] In the attached picture:

[0100] Figure 1 A schematic isometric illustration of an electrically heated fresh air heat exchanger according to the invention is shown;

[0101] Figure 2 A schematic diagram showing an end side of an electrically heated fresh air heat exchanger according to the present invention;

[0102] Figure 3 a schematic diagram showing the service side of an electrically heated fresh air heat exchanger according to the present invention; and

[0103] Figure 4 shows a schematic diagram of the inlet area of ​​a treatment plant with an electrically heated fresh air heat exchanger and a double gate on the inlet side;

[0104] Identical or functionally equivalent elements are provided with the same reference symbols in all figures. DETAILED DESCRIPTION

[0105] exist Figures 1 to 3 The fresh air heat exchanger 100 schematically shown in FIG. 1 is used to provide a heated fresh air heat flow inside a processing device 10 for workpieces (not shown).

[0106] The processing device 10 is, for example, a drying device 12 for drying workpieces.

[0107] The workpiece is, for example, a vehicle body.

[0108] In particular, to simplify the description of the fresh air flow, Figures 1 to 3 A three-dimensional coordinate system with x, y, and z axes is introduced.

[0109] Fresh air heat exchanger 100 comprises a filter unit 102 , a sound damping unit 104 , a radial fan 106 and two electrically heated heat transfer units 108 , which are accommodated together in a housing 110 .

[0110] The housing 110 has a service side 112 in which two maintenance access openings 114 are arranged.

[0111] The filter unit 102 and the sound damping unit 104 are arranged above the radial fan 106 .

[0112] exist Figure 1 In the embodiment of FIG. 1 , the sound damping unit 104 includes four square sound damping elements.

[0113] exist Figure 2 It can be seen in FIG. 1 that fresh air 116 , which is preferably drawn in from the surrounding work area, first flows through filter unit 102 in the y-direction, ie in the horizontal direction, in order to filter possible impurities from the fresh air 116 .

[0114] The sucked-in fresh air 116 can be ambient air, ie ambient air from inside or outside the room in which the treatment device 10 is installed, but can also be purified exhaust air.

[0115] The sucked-in fresh air 116 describes a first U-shaped flow path in the yz plane upstream of the radial compressor 106 , ie, on its suction side.

[0116] The fresh air flow downstream of the filter unit 102 passes through the sound damping unit 104 along a first flow path 118 in the z-direction, ie in the vertical direction.

[0117] The fresh air then flows through the radial fan 106 in the y-direction, ie again in the horizontal direction.

[0118] exist Figure 3 , it is shown that radial fan 106 deflects the fresh air flow into the xz plane.

[0119] On the downstream side of the radial fan 106 , ie on the pressure side, the fresh air flows in the x-direction, ie in the horizontal direction, along a straight second flow path 120 .

[0120] After radial fan 106 , the deflected fresh air flow flows through or around two heat exchange units 108 arranged one behind the other along second flow path 120 .

[0121] Here, heat energy generated by means of heating resistors, preferably heating wires, of electrically heated heat transfer unit 108 is transferred to the fresh air flow before the fresh air flow leaves housing 110 or is directed therefrom as heated fresh air 122 or heated fresh air hot flow.

[0122] Preferably, a temperature sensor 123 and a measuring tube 124 (such as Figure 4 ) to measure or verify that the heated fresh air 122 reaches the rated temperature.

[0123] Preferably, for the case where a split-flow heat exchanger is used for supplying the inlet lock and the intermediate lock or the outlet lock, the standard volume flow at the outlet of the fresh air heat exchanger 100 is 4250 Nm 3 / h and 12000Nm 3 In the case of a single fresh air heat exchanger 100 for supplying all locks, the standard volume flow is up to 24000 Nm 3 / h.

[0124] exist Figure 4 Schematically, an inlet region of a treatment device 10 , for example a drying device 12 , is shown in FIG.

[0125] The processing device 10 includes a processing chamber 200 having a plurality of processing chamber sections, wherein Figure 1 A first process chamber section 202 or first heat generating zone is shown in FIG.

[0126] The first process chamber section 202 is associated with a circulating air module 204 or a circulating air assembly.

[0127] The circulating air module 204 comprises a circulating air fan 206 , a measuring socket 208 for manual measurements, and a heat exchanger 210 .

[0128] Furthermore, a filter unit 212 is arranged in the first treatment chamber section 202 , which filters the circulating air which is guided back from the circulating air module 204 via the circulating air duct 211 .

[0129] In addition, according to Figure 4 In the embodiment of FIG. 2 , the process chamber 200 comprises a two-stage lock 214 , which preferably forms a line-based air curtain in order to, inter alia, keep the solvent in the process chamber 200 or prevent it from being discharged into the environment.

[0130] The lock 214 has a first stage 216 and a second stage 218 , wherein the workpieces first pass through the first stage 216 and then the second stage 218 , with reference to a transport direction 220 of the workpieces within the process chamber 200 .

[0131] Preferably, the first stage 216 and the second stage 218 are arranged directly one after the other in the conveying direction 220 , ie without intermediate elements.

[0132] However, in an advantageous embodiment, it is also conceivable that a pivotable cover plate can be arranged between the stages 216 , 218 , which, in the outwardly pivoted state, serves as a physical barrier that supports the gate function and simultaneously stabilizes the air flow of the first stage 216 .

[0133] Each stage 216 , 218 of the gate 214 is associated with a filter unit 222 , 224 to ensure that impurities from the respective air supply are not applied to the workpiece via the slit nozzles (not shown) of the stages 216 , 214 of the gate 214 .

[0134] Each stage 216 , 218 is also associated upstream of the filter unit 222 , 224 with a measuring cannula 226 , 228 for manual measurement, via which the value of the physical quantity can be monitored manually, in particular during operation of the lock 214 .

[0135] As above combined Figures 1 to 3 As described above, the heated fresh air 122 is supplied from the fresh air heat exchanger 100 to the damper 214 via the fresh air supply portion 230 .

[0136] The fresh air supply 230 , on the one hand, conducts the heated fresh air 122 to the first stage 216 , which forms a fresh air curtain.

[0137] In the flow path from the fresh air supply 230 to the first stage 216 of the gate 214 (which is supplied with a preferably magnitude of 4250 Nm 3 Another measuring sleeve 231 for manual measurement, a compensator 232 and a throttle mechanism 233 are arranged for a constant fresh air volume flow of / h. The compensator 232 is an element for compensating for the movement in the corresponding pipeline of the fresh air supply 230, especially in the case of thermal length changes, vibrations, wall holes or settlement phenomena.

[0138] A temperature sensor 234 and a volume flow sensor 236 , in particular a back pressure sensor, are arranged upstream of the throttle element 233 and downstream of the measuring socket 226 .

[0139] Furthermore, the fresh air supply 230 branches off at a branch 238 in the direction of the second stage 218 in order to also supply fresh air to the second stage 318 .

[0140] A further compensator 240 and an adjustable and / or controllable motor-driven throttle mechanism 242 are arranged downstream of the branch 238 .

[0141] The motor-driven throttle element 242 can be used to adjust, ie, control and / or regulate, the fresh air quantity that can be supplied to the second stage 218 .

[0142] The second stage 218 is supplied essentially with circulating air from the first process chamber section 202 , which is sucked in by means of a sluice fan 243 .

[0143] In other words, the sluice fan 243 supplies the circulating air line of the second stage 218 with circulating air from the adjacent first process section 202 .

[0144] The circulating air quantity is likewise regulated and / or adjusted by means of a motor-driven throttle element 244 .

[0145] A further compensator 246 and a further measuring socket 248 for manual measurement are arranged downstream of the motor-driven throttle element 244 before the branched fresh air flow is fed to the circulating air flow.

[0146] The second stage 218 of the gate 214 is also provided by a preferably 10000 Bm 3 A constant volume flow of 1.5 liters / h forms an air curtain, including circulating air and fresh air.

[0147] A further throttle element 250 for adjusting the volume flow is arranged downstream of the fresh air supply 230 into the circulating air flow.

[0148] Furthermore, in order to compensate for line movements in the region of the sluice fan 243 , a further compensator 252 or 254 is arranged respectively directly upstream and downstream of the sluice fan 243 .

[0149] The rotation speed of the radial compressor 106 of the fresh air heat exchanger 100 and the amount of fresh air delivered or supplied therewith depend on how much air mass flow is required for the treatment process or drying process. Since the amount of fresh air in particular of the first stage 216 of the lock 214 must remain constant in order to achieve an optimal lock function, the excess amount of fresh air is supplied to the second stage 218, i.e. the circulating air stage, via the branch 238.

[0150] For this reason, a temperature sensor 234 and a volume flow sensor 236 are provided in the fresh air supply 230. With the aid of these two measuring devices, a (standard) volume flow can be determined, which serves as a regulating value for a throttle 242 driven by the motor. The throttle 242 can be adjusted so that the fresh air flow to the first stage 216 is always constant and the excess fresh air portion is directed to the second stage 218.

[0151] A pressure sensor 256 is arranged in front of the gate gap or gate nozzle of the second stage 218 and in particular behind the filter unit 224, whose pressure difference relative to the environment, for example the workshop, is used as a control variable for the frequency-controlled gate fan 243. This differential pressure also ensures that the second stage 218 is also loaded with a constant air flow. The arrangement after the filter unit 224 ensures that contamination in the filter unit 224 is insignificant for the pressure measurement.

[0152] As already mentioned, the air flow can consist of pure recirculated air, but also of a mixture of recirculated air and fresh air.

[0153] If the drying process is carried out with a high fresh air volume, ie a high dryer load, the excess fresh air portion is correspondingly high, preferably up to a maximum of 7500 Nm 3 / h. Therefore, the proportion of recirculated air mixed in for the second stage 218 is lower.

[0154] In contrast, at low load rates, ie low dryer load rates, only a few workpieces (eg vehicle bodies) are located in the drying device 12. Here, the amount of fresh air provided by the fresh air heat exchanger is just sufficient to supply fresh air to the first stage 216 of the lock 214.

[0155] In this case, the motor-driven throttle element 242 is completely or largely closed, and the air for the second stage 218 must be completely sucked in from the adjacent first process chamber section 202 by means of the sluice fan 243 .

[0156] The advantage of supplying the second stage 218 with an excess fresh air portion depending on the load rate of the treatment plant 10 is that fresh air is no longer mixed directly into the circulating air module 204 as before, which makes all the fresh air of the lock 214 available in order to help minimize the solvent content in the atmosphere at the edge regions of the treatment chamber 200. In this way, the risk of recondensation of the solvent in these cooler edge regions is better offset.

[0157] Description of Reference Numerals

[0158] 10. Processing Equipment

[0159] 12Drying equipment / dryer

[0160] 100 Fresh air heat exchanger

[0161] 102 Filter unit

[0162] 104 Sound Damping Unit

[0163] 106 Radial Fan

[0164] 108 Heat transfer unit

[0165] 110 Housing

[0166] 112 Service Side

[0167] 114 Maintenance Access Department

[0168] 116 Breathing fresh air

[0169] 118 First flow path

[0170] 120 Second flow path

[0171] 122 Heated Fresh Air

[0172] 123 Temperature Sensor

[0173] 124 Measuring sleeve for manual measurement

[0174] 200 treatment room

[0175] 202 Processing chamber section / first heating zone

[0176] 204 Circulating air module / circulating air assembly

[0177] 206 circulating air ventilator

[0178] 208 Measuring sleeve for manual measurement

[0179] 210 Heat exchanger

[0180] 211 Circulation air guide

[0181] 212 Filter unit

[0182] 214 Two-level gate

[0183] 216 First level of the gate

[0184] 218 Second level of the gate

[0185] 220 Conveying direction

[0186] 222 Filter unit

[0187] 224 Filter unit

[0188] 226 Measuring sleeve for manual measurement

[0189] 228 Measuring sleeve for manual measurement

[0190] 230 Fresh air guide

[0191] 231 Measuring sleeve for manual measurement

[0192] 232 Compensator

[0193] 233 Throttle mechanism

[0194] 234 Temperature Sensor

[0195] 236 Volume Flow Probe

[0196] 238 branches

[0197] 240 Volume Flow Probe

[0198] 242 Motor-driven throttling mechanism

[0199] 243 Sluice Fan

[0200] 244 Motor-driven throttling mechanism

[0201] 246 Compensator

[0202] 248 Measuring sleeve for manual measurement

[0203] 250 throttle mechanism

[0204] 252 Measuring sleeve for manual measurement

[0205] 254 Measuring sleeve for manual measurement

[0206] 256 pressure sensor

Claims

1. A fresh air heat exchanger (100) for heating a fresh air flow, comprising: - at least one ventilator (106) for drawing in fresh air and generating a fresh air flow, and - At least one electrically heated heat transfer unit (108) for transferring thermal energy to said fresh air flow.

2. The fresh air heat exchanger (100) according to claim 1, characterized in that: At least one of the electrically heated heat transfer units (108) includes at least one heating resistor mechanism.

3. The fresh air heat exchanger (100) according to claim 1 or 2, characterized in that: At least one of the electrically heated heat transfer units (108) is arranged downstream of at least one of the ventilators (106).

4. The fresh air heat exchanger (100) according to any one of claims 1 to 3, characterized in that: The fresh air heat exchanger (100) has at least one filter unit (102) for filtering the drawn-in fresh air.

5. The fresh air heat exchanger (100) according to any one of claims 1 to 4, characterized in that: The fresh air heat exchanger (100) has at least one sound damping unit (104) for reducing the sound emission of the fresh air flow.

6. The fresh air heat exchanger (100) according to claim 5, characterized in that: At least one of the filter units (102) and / or at least one of the sound damping units (104) is arranged upstream of at least one of the ventilators (106).

7. The fresh air heat exchanger (100) according to claim 5 or 6, characterized in that: At least one of the filter units (102) and / or at least one of the sound damping units (104) is at least partially arranged above at least one of the ventilators (106).

8. The fresh air heat exchanger (100) according to any one of claims 1 to 7, characterized in that: The fresh air heat exchanger (100) has at least two, preferably three, electrically heated heat transfer units (108).

9. The fresh air heat exchanger (100) according to claim 8, characterized in that: The electrically heated heat transfer units (108) are arranged sequentially along the fresh air flow.

10. The fresh air heat exchanger (100) according to any one of claims 1 to 9, characterized in that: A first flow path (118) of the fresh air flow upstream of the ventilator (106) is perpendicular to a second flow path (120) of the fresh air flow downstream of the ventilator (106).

11. The fresh air heat exchanger (100) according to any one of claims 1 to 10, characterized in that: At least one of the ventilators (106) is a radial ventilator.

12. The fresh air heat exchanger (100) according to any one of claims 5 to 11, characterized in that: The fresh air heat exchanger (100) comprises a housing (110), in which at least one filter unit (102), at least one sound damping unit (104), at least one ventilator (106) and at least one electrically heated heat transfer unit (108) are at least partially accommodated.

13. The fresh air heat exchanger (100) according to claim 12, characterized in that: The housing (110) includes a service side (112) having at least one maintenance access (114).

14. The fresh air heat exchanger (100) according to any one of claims 1 to 13, characterized in that: A preheating device for preheating the fresh air flow is arranged upstream of at least one of the ventilators, wherein the preheating device is a heat pump, a regenerative thermal, in particular purely electrically driven and flameless oxidation device, or a solar thermal device comprising thermal oil or water.

15. Use of a fresh air heat exchanger (100) according to any one of claims 1 to 14 for heating a fresh air flow which is supplied to a treatment device for workpieces, in particular a drying device for vehicle bodies.

16. A method for providing heated fresh air with an electrically heated fresh air heat exchanger (100), wherein the method comprises the following steps: - drawing fresh air (106) from the environment of the fresh air heat exchanger (100), - filtering the sucked fresh air (116), - reducing the sound emission of the sucked fresh air (106), - deflecting the flow direction of the fresh air flow and compressing said fresh air flow, - transferring heat energy generated by at least one heating resistor means to the fresh air flow, and - Expelling the heated fresh air (122).

17. The method according to claim 16, characterized in that The method further comprises the step of preheating the fresh air in a preheating device, wherein the preheating device is a heat pump, a regenerative thermal, in particular purely electrically driven and flameless oxidation device, or a solar thermal device including thermal oil or water.

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