Drying system and method for drying coating of tank

Abstract

The invention relates to a drying system (100) for drying a coating of a tank, the drying system comprising a drying chamber (104) having a drying line (106) with a preheating section (108) and a polymerization chamber (114), a transfer device (124) capable of moving the tank through the drying chamber (114), a heating system capable of heating the tank through the preheating section (108), the heating system is used for applying temperature control processing fluid to the tank in the drying chamber (104), the heating system is connected to a control device (122) for signal communication, the preheating section (108) is provided with a first preheating chamber (110) and a second preheating chamber (112) downstream of the first preheating chamber (110), and the control device (122) is designed to control the heating system, so that the second preheating chamber (112) is communicated with the first preheating chamber (110). The tank in the first preheating chamber (110) is heated to a first temperature, preferably lower than 80 DEG C, and the tank in the second preheating chamber (112) is heated to a second temperature, preferably lower than 120 DEG C, where the second temperature is higher than the first temperature. The temperature gradient of the tank along the drying line (106) is made low to a degree to reduce sublimation of the tank coating in order to prevent condensation formation.

Description

Field of the Invention

[0001] The present invention relates to a drying system and method for drying a coating of a tank. Background Art

[0002] Drying systems for drying coatings of tanks are generally known. Such drying systems can be designed to dry the tank coating on the inner or outer surface of the tank. A drying system for drying the tank coating inside the tank is also referred to as an internal baking oven or IBO. A drying system for drying the tank coating on the outer surface of the tank is also referred to as a "pin oven".

[0003] In a process step before the drying system, a varnish is applied to the inner wall forming a cavity. In the drying system, the coating is dried and / or polymerized. For this purpose, the tank is moved through the drying system and exposed to hot air. Similarly, the coating is applied to the outer wall of the tank and then dried and / or polymerized in the pin oven.

[0004] The drying system can have a number of drying chambers arranged one behind the other, in which the water contained in the coating evaporates, the tank is heated to the polymerization temperature and / or held at the polymerization temperature for a predefined polymerization period.

[0005] Condensate is produced when drying the tank coating. In addition, particles are deposited during the drying process. The condensate and particles block the above-mentioned drying systems to such an extent that they have to be cleaned regularly, which is an expensive and time-consuming process. In normal operation, such drying systems are cleaned manually and / or with dry ice. This cleaning is so time-consuming that millions of tanks cannot be produced during each cleaning process. In addition, this cleaning can be harmful to the health of the cleaning personnel.

[0006] In the past, coatings containing bisphenol were often used, in which bisphenol (BPA) was used as an adhesive. However, bisphenol can have a carcinogenic effect, which is why the use of coatings containing BPA has been prohibited in many countries. One disadvantage of using BPA-free coatings is that they result in significantly higher condensate deposition and higher particle contamination. The existing problems of condensate and particle deposition are thus exacerbated by the use of BPA-free coatings.

[0007] The object of the present invention is to provide a drying system and method that mitigate or eliminate one or more of the mentioned disadvantages. In particular, the object of the present invention is to provide a solution for reducing condensation and / or particle contamination during the drying of the tank coating. Summary of the Invention

[0008] This task is solved by a drying system and method according to the features of the independent claims. Further advantageous embodiments of these aspects are indicated in the respective dependent patent claims. The features described and shown in the patent claims, the description and the drawings can be combined with one another in any technically useful way, thereby indicating further embodiments of the invention.

[0009] According to a first aspect, the above task is solved by a drying system for drying a coating of a can, the drying system comprising a drying chamber, a conveying device, a heating system, the drying chamber having a drying line which has a preheating section and a polymerization chamber, the can being movable through the drying chamber by means of the conveying device, the heating system being adapted to apply a temperature-controlled treatment fluid to the can within the drying chamber, wherein the heating system is coupled to a control device for signal communication, the preheating section having a first preheating chamber and a second preheating chamber downstream of the first preheating chamber, and the control device being arranged to control the heating system such that the can in the first preheating chamber is heated to a first temperature which is preferably below 80 °C, particularly below 70 °C, for example 65 °C, and the can in the second preheating chamber is heated to a second temperature which is preferably below 120 °C, particularly below 110 °C, for example 100 °C, wherein the second temperature is higher than the first temperature such that the temperature gradient of the can along the drying line is low to the extent of reducing the sublimation of the can coating in order to prevent the formation of condensate, and / or wherein the heating system is arranged and designed to act on the treatment fluid at a transfer temperature which is below 800 °C, in particular below 700 °C, preferably below 600 °C, on which treatment fluid, such that the combustion products containing particles are reduced in order to minimize particle contamination.

[0010] The present invention is based on the recognition that the formation of condensate within the drying system is caused substantially by the sublimation of the can coating or the paint forming the can coating. In the prior art, water-based can coatings are typically heated so rapidly that the water evaporates quickly and carries components of the can coating or varnish during the evaporation process. The effect behind this finding is also known as steam distillation.

[0011] The present invention is also based on the recognition that by slowing down the heating of the can in the first section of the drying line, the sublimation of the can coating can be reduced or avoided, thereby reducing the formation of condensate. For this purpose, the drying system comprises a first preheating chamber and a second preheating chamber, wherein the can is heated to a lower temperature in the first preheating chamber than in the second preheating chamber.

[0012] Furthermore, the present invention is based on the recognition that it is advantageous to heat-treat the process fluid only at a low transfer temperature of less than 800 °C, thereby reducing the particulate-containing combustion products to minimize particulate contamination of the drying system. It should be noted that the process fluid in such a drying system usually does not consist of fresh air, but is usually operated with recirculated air in order to improve energy efficiency. This recirculated air usually already contains evaporated coatable components, which produce particles that subsequently contaminate the drying system when reheated, for example, by a gas burner at 1200 °C. The present invention is also based on the recognition that such particulate deposition can be reduced by using a transfer temperature of less than 800 °C (for example, by using a porous burner), which will be explained in more detail below.

[0013] The drying system is designed to dry coatings for cans. The cans can be cans for containing food, especially food and / or beverages. The can coating can be a varnish for coating the inner wall and / or outer wall of the can. The drying system itself can be an internal dryer and / or a pin oven.

[0014] The drying system includes a drying chamber having a drying line with a preheating section and a polymerization chamber. The drying chamber preferably includes an inlet side and an outlet side. The drying chamber also preferably has a chamber inlet for the cans to enter on the inlet side and a chamber outlet for the cans to leave on the outlet side. The cans are moved, for example, by a conveyor belt of a conveying device between the chamber inlet and the chamber outlet. The conveyor belt can be, for example, fluid-permeable. The polymerization chamber preferably has a heating section and a temperature-maintaining section, where the cans are heated to a polymerization temperature, for example, from 100 °C to 200 °C, in the heating section and maintained at this polymerization temperature in the temperature-maintaining section. The heating section and / or the temperature-holding section can be formed as separate sub-chambers, which are, for example, fluidically separated from each other or can be separate. Fluid separation can be achieved, for example, by using an air lock.

[0015] In the IBO, the cans are usually exposed to the heat-treatment fluid from above, which then passes through the conveyor belt and is supplied from the conveyor belt to the recirculated air and / or the exhaust system. Furthermore, the drying chamber can have different flow media so that the cans can be exposed to the process fluid as evenly as possible.

[0016] Furthermore, the drying chamber preferably has two or more fluid supply lines, which are specifically arranged and designed to supply recirculated air and / or fresh air to the drying chamber. Furthermore, it is preferred that the drying chamber is substantially fluid-impermeable (for example, by means of the chamber walls).

[0017] The drying system includes a conveying device through which the cans can be moved through the drying chamber. The conveying device can, for example, include the conveyor belt described above or can be in the form of a pin chain.

[0018] The drying system includes a heating system for applying a temperature-controlled process fluid to the cans inside the drying chamber. For this purpose, the heating system can have a fluid supply, a fluid outlet, and / or a recirculated air supply. It is particularly preferred that the heating system is arranged and designed to apply the temperature-controlled process fluid to the cans in the preheating section, particularly in the first preheating chamber and the second preheating chamber and in the polymerization chamber, independently of each other by means of the temperature-controlled process fluid, such that the process fluid supplied to the aforementioned chambers can be adjusted and / or controlled in a chamber-dependent manner with respect to the fluid volume and / or the fluid temperature. Preferably, the temperature-controlled process fluid is supplied to the polymerization chamber such that the cans in the polymerization chamber have a temperature between 150 °C and 250 °C, for example 200 °C.

[0019] The process fluid is preferably air. The process fluid can include fresh air and / or recirculated air or consist of fresh air and / or recirculated air.

[0020] In an alternative, the heating system is coupled to a control device for signal communication. The preheating section has a first preheating chamber and a second preheating chamber downstream of the first preheating chamber. Here, downstream is specifically understood in the direction of movement of the cans. The cans thus enter the drying system, first pass through the first preheating chamber, then enter the second preheating chamber, and are then guided through the polymerization chamber.

[0021] The control device is designed to control the heating system such that the cans in the first preheating chamber are heated to a first temperature and the cans in the second preheating chamber are heated to a second temperature. This results in the cans in the first preheating chamber being heated slowly first at a lower temperature (particularly below 80 °C). As a result, the expected sublimation is reduced. In the second preheating chamber, the cans are then heated to a temperature at which the water component of the can coating evaporates.

[0022] The first preheating chamber and the second preheating chamber are designed as separate chambers. In particular, these can have different drying line lengths such that the temperature gradient of the cans can be adjusted as required.

[0023] Preferably, the first drying chamber, the second drying chamber, and / or the conveying device are arranged and designed and / or the control device is set such that the cans move through the first drying chamber with a first passage time between 20 - 90 seconds, particularly between 30 - 60 seconds, and move through the second drying chamber with a second passage time between 20 - 90 seconds, particularly between 30 - 60 seconds.

[0024] In a second alternative, the heating system is arranged and designed to act on the process fluid at a transfer temperature below 800 °C, such that particulate-containing combustion products are reduced in order to reduce particulate contamination. The transfer temperature should be specifically understood as the temperature at which the process fluid is heated. This can be, for example, a unit of the heating system that heats the process fluid, such as an electric heating wire or a porous burner, etc. This is contrary to the method taken in the prior art, where the process fluid is typically heated using a gas burner, and the gas flame of the gas burner is, for example, 1200 °C. Thus, the heating system described above is capable of heating the process fluid at a lower temperature (i.e., below 800 °C), thereby reducing or avoiding particulate formation.

[0025] In a preferred embodiment of the drying system, it is provided that the drying system includes two alternatives, namely, the heating system is coupled to a control device for signal communication, the preheating section has a first preheating chamber and a second preheating chamber downstream of the first preheating chamber, the control device is arranged to control the heating system such that the cans in the first preheating chamber are heated to a first temperature and the cans in the second preheating chamber are heated to a second temperature, wherein the second temperature is higher than the first temperature, such that the temperature gradient of the cans along the drying line is low to such an extent that sublimation of the can coating is reduced in order to prevent the formation of condensate, and the heating system is arranged and designed to act on the process fluid at a transfer temperature less than 800 °C, such that particulate-containing combustion products are reduced in order to reduce particulate contamination.

[0026] A preferred embodiment of the drying system is characterized in that the first preheating chamber, the second preheating chamber, and the polymerization chamber each have an exhaust fan, such that a first exhaust gas volume of the exhaust gas of the first preheating chamber, a second exhaust gas volume of the exhaust gas of the second preheating chamber, and a third exhaust gas volume of the exhaust gas of the polymerization chamber can be adjusted independently of each other.

[0027] For example, the first preheating chamber may have a first exhaust fan, the second preheating chamber may have a second exhaust fan, and the polymerization chamber may have a third exhaust fan. These exhaust fans can be specifically coupled to the exhaust ducts described in more detail below. The fresh air volume in the individual chambers can be adjusted independently of each other by separate exhaust fans.

[0028] In a further preferred embodiment of the drying system, the first preheating chamber has a first drying line, the second preheating chamber has a second drying line, and the polymerization chamber has a polymerization line, and the first drying line is longer than the second drying line, and / or the first drying line and the second drying line together are longer than the polymerization line.

[0029] Since the first temperature is lower than the second temperature, the temperature gradient during the heating process of the can is kept low by the long first drying line. The low temperature gradient ensures that sublimation is kept low or avoided. In particular, it is preferred that the length of the preheating line composed of the first drying line and the second drying line is such that sublimation is avoided. This can be achieved in particular by the preheating line being longer than the polymerization line.

[0030] A preferred design of the drying system is characterized in that the first preheating chamber, the second preheating chamber, and the polymerization chamber each have an exhaust duct for discharging exhaust gas, such that the exhaust gases from the first preheating chamber, the second preheating chamber, and the polymerization chamber are substantially not mixed with each other, thereby reducing condensate in the exhaust duct.

[0031] The present invention is also based on the recognition that exhaust ducts (which are typically contaminated) in the drying system are necessary because the exhaust gas flows from different chambers have different temperatures. Once these exhaust gas flows with different temperatures are mixed together, condensate is usually formed. The condensate precipitates in the exhaust ducts and blocks them, making the above-mentioned cleaning necessary. Separate embodiments of the exhaust ducts prevent such condensate formation.

[0032] Particularly preferably, the exhaust duct leads to a condensate chamber, and the condensate chamber is arranged and designed to separate the condensate from the exhaust gas. Thus, the condensate is deliberately formed first in the condensate chamber rather than in the exhaust duct itself. The condensate chamber can, for example, have a cooling element such that the condensate is deliberately formed thereon.

[0033] In a preferred design of the drying system, a removable condensate separator is further provided in the condensate chamber. The condensate separator can, for example, be designed in the form of a box. The removable condensate separator has the advantage of being easy to clean. The condensate separator can, for example, have a cooling element or be a cooling element.

[0034] In a further preferred embodiment of the drying system, it is provided that this includes a fluid interface which is arranged and designed to fluidly and / or thermally couple the first preheating chamber and / or the second preheating chamber to the device for manufacturing the can, such that the processing fluid introduced into the first preheating chamber and / or the second preheating chamber can be at least partially provided by the device for manufacturing the can and / or can be thermally influenced by the device for manufacturing the can.

[0035] The device for manufacturing cans can be any device within a canning factory. These are devices that directly manufacture such cans, such as forming devices, and also indirectly acting devices, such as waste gas purifiers. Specifically, the waste gas purifier has a high waste gas temperature, and this waste gas temperature can be used to advantageously heat the process fluid. Thereby, the energy efficiency of the drying system can be further improved. For this purpose, the waste gas from the device for manufacturing cans can be directly used as the process fluid. Alternatively, the waste gas can be thermally coupled to the process fluid by means of a heat exchanger, such that the thermal energy of the waste gas from the device for manufacturing cans can be separated into the process fluid.

[0036] In a further preferred embodiment of the drying system, the heating system includes a combustion unit and / or an electric heating unit, which is arranged and designed such that the transfer temperature is less than 800 °C, preferably less than 700 °C, particularly less than 600 °C.

[0037] The combustion unit can be, for example, a gas burner. The gas can be, for example, LNG, natural gas, and / or hydrogen. For example, the electric heating unit can include heating wires.

[0038] In a further preferred embodiment, the combustion unit is or includes a porous burner. Specifically, the porous burner has a porous structure where the combustion reaction occurs. Thus, the porous burner generally does not have an open flame, such that the transfer temperature is reduced.

[0039] In a further preferred embodiment of the drying system, it is provided that fresh air can be supplied to the process fluid such that the temperature of the process fluid can be adjusted by the fresh air volume of the fresh air. For this purpose, the drying system preferably has an air supply duct. Specifically, preferably, the first preheating chamber, the second preheating chamber, and / or the polymerization chamber each have an air supply duct.

[0040] The preferred design of the drying system is characterized by the fact that an air lock is arranged between the first preheating chamber, the second preheating chamber, and / or the polymerization chamber such that during normal operation, the fluid exchange between the first preheating chamber, the second preheating chamber, and / or the polymerization chamber is at least reduced.

[0041] Such an air lock between separate chambers has the advantage that the target temperature can be set particularly advantageously in a controlled manner, especially when the predetermined temperature is actually set.

[0042] In a further preferred embodiment of the drying system, the first preheating chamber, the second preheating chamber, and / or the polymerization chamber is provided with a cleaning unit, which is arranged and designed to separate condensates and / or particles.

[0043] The present invention is based on the following understanding: Condensate and / or particles can also occur in these individual chambers, such that the condensate and / or particles can also settle in the chambers during operation and not only in the exhaust ducts. The formation of condensate and / or particles can thus be further reduced by a single cleaning unit or by cleaning units arranged in the respective chambers. Preferably, the first preheating chamber has a first cleaning unit, the second preheating chamber has a second cleaning unit and / or the polymerization chamber has a third cleaning unit.

[0044] In a preferred embodiment, it is provided that the cleaning unit, in particular the first cleaning unit, the second cleaning unit and / or the third cleaning unit, is designed to operate mechanically, electrostatically and / or pressure-based. With such a cleaning unit, particles and / or condensate can be advantageously separated in the individual chambers such that they accumulate exactly in the cleaning unit and do not contaminate areas of the drying system that are difficult or impossible to clean.

[0045] According to another aspect, the above task is solved by a method for coating a drying can, in particular by means of a drying system according to one of the above embodiments, the method comprising the steps of: conveying the can along a drying line having a first preheating chamber and a second preheating chamber downstream of the first preheating chamber, heating the can to a first temperature preferably below 80 °C by exposure to a temperature-controlled treatment fluid in the first preheating chamber, heating the can to a second temperature preferably below 120 °C by exposure to a temperature-controlled treatment fluid in the second preheating chamber, wherein the second temperature is higher than the first temperature such that the temperature gradient of the can along the drying line is low to the extent that sublimation of the can coating is reduced in order to prevent the formation of condensate.

[0046] It may preferably be provided that the method comprises the steps of temperature-controlling the treatment fluid at a transfer temperature of less than 800 °C, in particular less than 700 °C, preferably less than 600 °C, such that particulate-containing combustion products are reduced in order to minimize particle contamination.

[0047] According to another aspect, the above task is solved by a method for coating a drying can, in particular by using a drying system according to one of the above embodiments, the method comprising the steps of: conveying the can along a drying line comprising a preheating section and a polymerization chamber, subjecting the can to a temperature-controlled treatment fluid, and temperature-controlling the treatment fluid at a transfer temperature of less than 800 °C, preferably less than 700 °C, in particular less than 600 °C, such that particulate-containing combustion products are reduced in order to reduce particle contamination.

[0048] The method and its possible enhanced features have features and method steps that make them particularly suitable for use in drying systems and their enhancements.

[0049] For further advantages, example variations, and other aspects of the details of the embodiments and their possible implementations, reference is also made to the previous description of the corresponding features of the device and the embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Referring to the drawings, preferred exemplary embodiments are illustrated by way of example. It shows:

[0051] Figure 1 : A schematic two-dimensional view of an exemplary embodiment of a drying system;

[0052] Figure 2 : Figure 1 A schematic two-dimensional cross-sectional view of the drying system shown in ;

[0053] Figure 3 : A schematic diagram of an exemplary method for coating a drying tank; and

[0054] Figure 4 : A schematic diagram of another method for coating a drying tank. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0055] In the figures, the same or functionally identical or similar elements are denoted by the same reference numerals.

[0056] Figure 1 and Figure 2 The drying system 100 shown in and is designed to dry the tank 102. The drying system 100 includes a drying chamber 104, and a drying line 106 extends through the drying chamber 104. The drying line 106 extends from an inlet at the left end of the drying system 100 to an outlet at the right end of the drying system 100. The drying chamber 104 includes a preheating section 108 and a polymerization chamber 114. The preheating section 108 includes a first preheating chamber 110 and a second preheating chamber 112. The polymerization chamber 114 is shown in a simplified form as it generally has two separate chambers, where the tank 102 is heated to a polymerization temperature in a heating chamber and the polymerization temperature is maintained in an insulation chamber.

[0057] In normal operation, the tank 102 is first moved by the transfer device 124 into the first preheating chamber 110, then into the second preheating chamber 112, and then into the polymerization chamber 114. A heating system including a first heating unit 116, a second heating unit 118, and a third heating unit 120 is used to expose the tank 102 within the drying chamber 104 to a temperature-controlled process fluid.

[0058] Specifically, the cans 102 are exposed to the treatment fluid such that they are first slowly heated in the first preheating chamber 110 to a temperature of, for example, 65 °C, then heated in the second preheating chamber 112 to a temperature of 100 °C and then heated in the polymerization chamber 114 to a polymerization temperature of, for example, 200 °C and held at this temperature.

[0059] For this purpose, the drying system includes control means (122) which are coupled to the heating system for signal communication. The control means 122 are designed to control the heating system such that the cans 102 in the first preheating chamber 110 are heated to a first temperature, for example 65 °C, and the cans 102 in the second preheating chamber 112 are heated to a second temperature, for example 100 °C. This is done such that the second temperature is higher than the first temperature. Thus, the temperature gradient of the cans 102 along the drying line 106 is set so low that sublimation of the can coating of the cans 102 is reduced in order to prevent condensate formation. This is especially due to the fact that heating the can coating, which usually contains water, too quickly causes foaming such that the evaporated water carries the colorant with it.

[0060] The drying system 100 is designed such that the fluid can be directed in each of the chambers 110, 112, 114, which fluid can be circulated during the process of the recirculated air and can also be disposed of. For this purpose, for example, the first preheating chamber 110 has a fluid interface 148. Fresh air can be supplied through the fluid interface 148. Alternatively, the first preheating chamber 110 can be fluidly and / or thermally coupled to the device for manufacturing the cans by means of the fluid interface 148 such that the treatment fluid introduced into the first preheating chamber 110 can be at least partially provided by the device for manufacturing the cans and / or can be thermally influenced by the device for manufacturing the cans.

[0061] Furthermore, the first preheating chamber 110 includes an air recirculation fan for circulating the recirculated air, which air recirculation fan is arranged between the chamber space and the mixing chamber 150. The recirculated air is in particular supplied from the preheating chamber 110 through the fluid recirculation unit 156 of the mixing chamber 150. Before the mixing chamber 150, the recirculated air is thermally influenced, in particular temperature-controlled, by means of the first combustion unit 152 and / or the first electrical heating unit 154. Among other things, the recirculated air serving as the treatment fluid is temperature-controlled by the combustion unit 152 and / or the electrical heating unit with a transfer temperature of less than 800 °C such that the combustion products containing particles are reduced in order to minimize particle contamination. The second preheating chamber 112 and the polymerization chamber 114 similarly include a second combustion unit 164, a second electrical heating unit 166, a third combustion unit 168 and a third electrical heating unit 170.

[0062] In addition, an exhaust duct 138 is provided to remove the initial exhaust gas 132 from the first preheating chamber 110. The exhaust duct 138 is coupled to an exhaust fan 126 for discharging the initial exhaust gas 132 from the first preheating chamber 110. In a similar manner, the second exhaust gas 134 can be discharged from the second preheating chamber 112 by means of a second exhaust fan 128 and a second exhaust duct 140. In addition, the third exhaust gas 136 can be discharged from the polymerization chamber 114 by means of a third exhaust fan 130 and a third exhaust duct 142.

[0063] The exhaust ducts 138, 140, 142 are each designed to be separate from each other and terminate in a condensate chamber 144. The condensate chamber 144 further includes a condensate separator 146 where the condensate of the first exhaust gas 132, the second exhaust gas 134, and the third exhaust gas 136 is selectively separated. The condensate separator 146 can be designed to be removable from the condensate chamber 144. The condensate separator 146 can be designed, for example, in the form of a box and can be removed like a box.

[0064] Figure 3 A method for drying the coating of the can 102 is shown. The method includes step 200: conveying the can 102 along a drying line 106 having a first preheating chamber 110 and a second preheating chamber 112 downstream of the first preheating chamber 110.

[0065] In addition, the method includes step 202: in the first preheating chamber 110, heating the can 102 to a first temperature preferably below 80 °C by exposure to a temperature-controlled process fluid; in addition, the method includes step 204: heating the can 102 in the first preheating chamber 112 to a first temperature preferably below 120 °C by exposure to a temperature-controlled process fluid;

[0066] Steps 202 and 204 are carried out in such a way that the second temperature is higher than the first temperature, so that the temperature gradient of the can 102 along the drying line 106 is low enough to reduce the sublimation of the can coating in order to prevent the formation of condensate.

[0067] Figure 4 Another method for drying the coating of the can 102 is shown. The method includes step 300: conveying the can 102 along a drying line 106 having a preheating section 108 and a polymerization chamber 114. In step 302, the can 102 is exposed to a temperature-controlled process fluid. In step 304, the process fluid is temperature-controlled at a transfer temperature below 800 °C so that the particulate-containing combustion products are reduced in order to reduce particulate contamination.

[0068] The advantages of the drying system 100 and the corresponding method described above are that the formation of condensates and particles within the drying system 100 is significantly reduced. On the one hand, this is achieved by maintaining a low temperature gradient in the preheating section 106 to reduce sublimation during the heating of the cans or can coatings. Among other things, this is made possible by the fact that a first preheating chamber 110 and a second preheating chamber 112 are provided, in which the can 102 is heated to a first temperature in the first preheating chamber 110 and to a second temperature in the second preheating chamber 112. This reduction or avoidance of sublimation is achieved in particular by a judicious choice of temperatures, specifically a first temperature below 80 °C, for example 65 °C, and a second temperature of approximately 100 °C.

[0069] Furthermore, the reduced formation of condensates or dust is achieved by a special form of tempering of the process fluid (i.e., maintaining a transfer temperature below 800 °C, in particular below 600 °C). It has been found that, among other things, the process fluid operated as recirculated air produces less dust formation.

[0070] A further advantage of the described drying system is that the formation of condensates and process residues can be specifically influenced such that, for example, the condensates settle in a defined manner in the condensate chamber, thus simplifying the cleaning of the drying system.

[0071] Reference Signs

[0072] 100 drying system

[0073] 102 can

[0074] 104 drying chamber

[0075] 106 drying line

[0076] 108 preheating section

[0077] 110 first preheating chamber

[0078] 112 second preheating chamber

[0079] 114 polymerization chamber

[0080] 116 first heating unit

[0081] 118 second heating unit

[0082] 120 third heating unit

[0083] 122 control device

[0084] 124 conveyor device

[0085] 126 first exhaust fan

[0086] 128 Second exhaust fan

[0087] 130 Third exhaust fan

[0088] 132 First exhaust gas

[0089] 134 Second exhaust gas

[0090] 136 Third exhaust gas

[0091] 138 First exhaust pipe

[0092] 140 Second exhaust pipe

[0093] 142 Third exhaust pipe

[0094] 144 Condensate chamber

[0095] 146 Condensate separator

[0096] 148 Fluid interface

[0097] 150 Mixing chamber

[0098] 152 First combustion unit

[0099] 154 First electric heating unit

[0100] 156 Fluid recirculation unit

[0101] 158 First cleaning unit

[0102] 160 Second cleaning unit

[0103] 162 Third cleaning unit

[0104] 164 Second combustion unit

[0105] 166 Second electric heating unit

[0106] 168 Third combustion unit

[0107] 170 Third electric heating unit

Claims

1. A drying system (100) for a coating of a drying tank (102), comprising a drying chamber (104), the drying chamber (104) having a drying line (106), the drying line (106) having a preheating section (108) and a polymerization chamber (114), - a conveying device (124) through which the tank (102) can be moved through the drying chamber (104), - a heating system for applying a temperature-controlled treatment fluid to the tank (102) within the drying chamber (104), - wherein, the heating system is coupled to a control device (122) for signal communication, the preheating section (108) having a first preheating chamber (110) and a second preheating chamber (112) downstream of the first preheating chamber (110), and the control device (122) being designed to control the heating system such that the tank (102) in the first preheating chamber (110) is heated to a first temperature preferably below 80 °C and such that the tank (102) in the second preheating chamber (112) is heated to a second temperature preferably below 120 °C, wherein the second temperature is higher than the first temperature such that the temperature gradient of the tank (102) along the drying line (106) is low enough to reduce sublimation of the coating of the tank to prevent condensate formation, and / or - wherein the heating system is arranged and designed to act on the treatment fluid at a transfer temperature below 800 °C to reduce particulate combustion products and thus reduce particulate contamination.

2. The drying system (100) according to claim 1, wherein, - the first preheating chamber (110), the second preheating chamber (112) and the polymerization chamber (114) each have an exhaust fan (126, 128, 130) such that a first exhaust volume of the exhaust of the first preheating chamber (110), a second exhaust volume of the exhaust of the second preheating chamber (112) and a third exhaust volume of the exhaust of the polymerization chamber (114) can be set independently of each other.

3. The drying system (100) according to one of the preceding claims, - wherein the first preheating chamber (110) includes a first drying line, the second preheating chamber (112) includes a second drying line, and the polymerization chamber (114) includes a polymerization line, and - the first drying line is longer than the second drying line, and / or the first drying line and the second drying line together are longer than the polymerization line.

4. The drying system (100) according to one of the preceding claims, - The first preheating chamber (110), the second preheating chamber (112), and the polymerization chamber (114) each have exhaust ducts (138, 140, 142) for discharging exhaust gas, such that the exhaust gases of the first preheating chamber (110), the second preheating chamber (112), and the polymerization chamber (114) are substantially not mixed with each other, thereby reducing condensation in the exhaust ducts (138, 140, 142).

5. The drying system (100) according to one of the preceding claims, - The exhaust ducts (138, 140, 142) lead into a condensate chamber (144), and the condensate chamber (144) is arranged and designed to separate condensate from the exhaust gas.

6. The drying system (100) according to any one of the preceding claims, wherein, The condensate chamber (144) includes a removable condensate separator (146).

7. The drying system (100) according to any one of the preceding claims, comprising: - A fluid interface (148) that is arranged and designed to fluidly and / or thermally connect the first preheating chamber (110) and / or the second preheating chamber (112) to a device for manufacturing cans, such that the processing fluid introduced into the first preheating chamber (110) and / or the second preheating chamber (112) can be at least partially provided by the device for manufacturing cans and / or can be thermally affected by the device for manufacturing cans.

8. The drying system (100) according to one of the preceding claims, - The heating system includes combustion units (152, 164, 168) and / or electric heating units (154, 166, 170), and the combustion units (152, 164, 168) and / or the electric heating units (154, 166, 170) are arranged and designed such that the transfer temperature is lower than 800 °C.

9. The drying system (100) according to one of the preceding claims, - The combustion units (152, 164, 168) are or include porous burners.

10. The drying system (100) according to one of the preceding claims, - Fresh air can be supplied to the processing fluid such that the temperature of the processing fluid can be adjusted by the volume of fresh air of the fresh air.

11. The drying system (100) according to one of the preceding claims, - An air lock is arranged between the first preheating chamber (110), the second preheating chamber (112), and / or the polymerization chamber (114) such that during normal operation, fluid exchange between the first preheating chamber (110), the second preheating chamber (112), and / or the polymerization chamber (114) is at least reduced.

12. The drying system (100) according to one of the preceding claims, - The first preheating chamber (110), the second preheating chamber (112) and / or the polymerization chamber (114) include cleaning units (158, 160, 162) arranged and designed for separating condensate and / or particles.

13. The drying system (100) according to one of the preceding claims, - The cleaning units (158, 160, 162) are designed to operate mechanically, electrostatically and / or based on pressure.

14. A method for coating a can for drying, comprising the steps of: - conveying the can along a drying line (106) having a first preheating chamber (110) and a second preheating chamber (112) downstream of the first preheating chamber (110); - heating the can to a first temperature preferably below 80 °C by exposure to a temperature-controlled process fluid in the first preheating chamber (110); - heating the can to a second temperature preferably below 120 °C by exposure to a temperature-controlled process fluid in the second preheating chamber (112), wherein the second temperature is higher than the first temperature such that the temperature gradient of the can along the drying line (106) is low enough to reduce sublimation of the can coating to prevent formation of condensate; 15. A method for coating a can for drying, comprising the steps of: - conveying the can along a drying line (106) having a preheating section (108) and a polymerization chamber (114); - applying a temperature-controlled process fluid to the can; - temperature-controlling the process fluid at a transfer temperature below 800 °C such that particulate combustion products are reduced to minimize particulate contamination.

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