EP1398587A2 - Dryer for objects, in particular for vehicle bodies, as well as method for its operation - Google Patents

Abstract

A dryer (1) for objects, in particular for vehicle bodies, has, in a manner known per se, a housing (2) in which a drying chamber (3) accommodating the objects is formed. There the objects are exposed to IR radiation which is generated by at least one catalytic emitter (5). The dryer (1) can be used as a device for cleaning air containing pollutants by supplying the supply air to the drying chamber (3) exclusively via the catalytically active layer (13) of the catalytic radiator (5), so that the air contained in the supply air is there organic impurities can be catalytically oxidized in a controlled manner. In this case, the catalytic radiator (5) must be heat-resistant in the sense that it does not require air cooling. The dryer (1) can be used to clean both contaminated air which has accumulated elsewhere and the air which has been produced in the dryer (1) and contains organic contaminants.

Description

a) einem Gehäuse, in dem ein die Gegenstände aufnehmender Trockenraum ausgebildet ist;

b) einem Anschluß für Zuluft;

c) einem Anschluß für Abluft;

d) mindestens einem Katalytstrahler, der seinerseits aufweist:

da) mindestens einen Anschluß für Verbrennungsgas;

db) eine katalytisch aktive Schicht, welcher das Verbrennungsgas zugeführt wird;

dc) mindestens einen Anschluß für Verbrennungsluft, der über eine Luftführung mit der katalytisch aktiven Schicht verbunden ist;

sowie
ein Verfahren zum Betreiben eines Trockners für Gegenstände, insbesondere Fahrzeugkarosserien, bei dem

a) die zu trocknenden Gegenstände in einen Trockenraum im Gehäuse des Trockners eingebracht werden;

b) die zu trocknenden Gegenstände in dem Trockenraum einer Infrarotstrahlung ausgesetzt werden, die von einem Katalytstrahler erzeugt wird, dessen katalytisch aktiver Schicht Verbrennungsgas und Verbrennungsluft zugeführt werden;

c) dem Trockenraum ständig Zuluft zugeführt und Abluft entnommen wird.

The invention relates to a dryer for objects, in particular for vehicle bodies

a) a housing in which a drying chamber accommodating the objects is formed;

b) a connection for supply air;

c) a connection for exhaust air;

d) at least one catalytic emitter, which in turn has:

da) at least one connection for combustion gas;

db) a catalytically active layer, to which the combustion gas is supplied;

dc) at least one connection for combustion air, which is connected to the catalytically active layer via an air duct;

such as
a method for operating a dryer for objects, in particular vehicle bodies, in which

a) the objects to be dried are placed in a drying chamber in the housing of the dryer;

b) the objects to be dried are exposed in the drying room to infrared radiation which is generated by a catalytic radiator, the catalytically active layer of which is supplied with combustion gas and combustion air;

c) supply air is constantly supplied to the drying room and extract air is extracted.

Dryers that use catalytic lamps as a heat source, are enjoying increasing popularity. This for good Reason: On the one hand is the primary energy used, namely the combustion gas (natural gas, propane, butane or liquid gas), very inexpensive compared to electrical energy. To the another can be one with such catalytic emitters Infrared radiation especially in that long-wave Create an area that is used for drying or firing coatings, especially paint finishes particularly, effectively is. Energy savings are also achieved by that essentially only the one to be dried Coating, but not other objects heated become.

Furthermore, the long-wave radiation from a catalytic emitter the property by a compared with short or medium-wave rays moderate energy density the subject Warm and dry gently.

It was previously recognized that in the catalytic active layer of catalytic emitters organic impurities are catalytically oxidized, which in the the Combustion air supplied to the catalytic heater are. So far, however, this fact has only been a positive one Side effect of using catalytic emitters considered and not used specifically. This was at the known dryers of the type mentioned not possible because they used catalytic emitters, who needed air cooling or the air flow in the Inside the dryer was not defined. It was there that is, fresh air is introduced into the drying room, which is not flowed inevitably over the catalytically active layer. Impurities contained in this supply air thus remained unoxidized, so that the removed from the dryer Exhaust air from a separate exhaust air cleaning device, for example a thermal, a regenerative or a catalytic afterburning device had to be fed. These devices then served often as collective disposal for everyone with organic Substances, especially exhaust air volume flows loaded with solvents, those in the entire facility, so not only in the dryer. These come with painting systems typically in particular from the spray booth, the Evaporation zone, the dryer, the paint mixing room or off other sources.

The known dryers of those mentioned Type thus required additional exhaust gas purification devices cause, of course, proportionate high costs.

The object of the present invention is a dryer of the type mentioned in such a way that on a separate exhaust gas cleaning device is dispensed with can be or at least the amount of exhaust air can be reduced so that the separate exhaust gas purification device kept smaller and therefore cheaper can be.

e) der Anschluß des Trockners für Zuluft ausschließlich mit dem Anschluß des Katalytstrahlers für Verbrennungsluft verbunden ist, derart, daß abgesehen von unvermeidlichen Leckagen des Gehäuses die gesamte Zuluft als Verbrennungsluft über den Katalytstrahler geführt wird;

f) der Katalytstrahler in dem Sinne hitzebeständig ausgeführt ist, daß er keiner Luftkühlung bedarf.

This object is achieved in that

e) the connection of the dryer for supply air is connected exclusively to the connection of the catalytic radiator for combustion air, such that, apart from unavoidable leakages in the housing, the entire supply air is conducted as combustion air via the catalytic radiator;

f) the catalytic heater is heat-resistant in the sense that it does not require air cooling.

The idea of the invention is as follows: if catalytic emitters are used that do not require air cooling, can put the entire in the drying room of the dryer Supply air via the connection of the catalytic lamp for forced air to be directed, so that all supply air that enters the drying room at least once on the catalytically active layer flowed past or through the catalytically active layer is. In this way it becomes possible to use the catalytic oxidative conversion of organic impurities to be carried out in the supply air as a controlled reaction, including quantitative predictions of reaction sales possible are.

In favorable cases, the single passage of the Supply air through the catalytically active layer of a catalytic lamp, to provide adequate cleaning.

The supply air supplied to the dryer can partially from the dryer itself, but also from other parts of the system originate, so that the dryer as a "collective disposal facility" So far for the entire system provided separate exhaust air cleaning devices can replace in whole or in part.

The catalytic emitter can have a connection via which is only supplied with air. This Supply air is placed in one place within the catalytic heater directed from which it is a surface of the catalytic flow to the active layer. This will Conditions created under which a controlled Implementation of the organic contained in the supply air Contamination takes place.

An even better efficiency is achieved with that embodiment achieved the invention in which the Catalytic emitter has a connection with a Pre-mixer is connected in the combustion gas and Supply air to be mixed together. This before Entry into the catalytic heater mixing takes place promotes from combustion gas and polluted supply air the catalytically activated oxidation of the organic Impurities, so that a higher degree of implementation is achieved becomes.

For convective heating of the objects to be dried a fan can be provided with which the air in the Drying room can be circulated.

In those cases where a one-off Passage of the supply air through the catalytically active layer adequate cleaning of a catalytic emitter an embodiment of the invention can be achieved are used in which the dryer is multi-stage is formed, with each stage in the in one of the Claims 1 to 4 described manner is formed and the connection for exhaust air from the upstream Stage with the connection for the supply air each downstream stage is connected. In this way passes through the supply air supplied to the dryer during the passage through the dryer several times a catalytically active Layer of a catalytic emitter with the result that the Implementation of organic contaminants more completely succeed. In principle, any number of such Stages are provided until the desired level of cleaning is reached.

The object of the present invention is also a Method for operating a dryer at the beginning Specify the type in which the in the dryer contained catalytic emitters in a targeted and controllable manner used to clean the supply air supplied to the dryer can be.

d) die gesamte dem Trockenraum zugeführte Zuluft abgesehen von unvermeidlichen Leckagen des Gehäuses des Trockners als Verbrennungsluft über die katalytisch aktive Schicht des Katalytstrahlers geführt wird;

e) ein Katalytstrahler verwendet wird, der in dem Sinne hitzebeständig ausgebildet ist, daß er keiner Kühlung bedarf.

This object is achieved in that

d) the entire supply air supplied to the drying room, apart from inevitable leaks in the housing of the dryer, is conducted as combustion air over the catalytically active layer of the catalytic radiator;

e) a catalytic radiator is used which is heat-resistant in the sense that it does not require cooling.

The advantages of this method according to the invention correspond analogous to the above-mentioned advantages of the invention Dryer.

Appropriate configuration of the method according to the invention are given in claims 6 to 10. This too achievable advantages find their counterpart in above Advantages of certain embodiments of the Dryer.

Figur 1:

schematisch einen zweistufigen Trockner zur Verwendung in einer Lackieranlage für Fahrzeugkarosserien;

Figur 2:

einen schematischen Schnitt einen Katalytstrahler, wie er in dem Trockner der Figur 1 Verwendung findet;

Figur 3:

den Katalytstrahler der Figur 2 in Kombination mit einem Vormischer, der wahlweise bei dem in Figur 1 dargestellten Trockner eingesetzt werden kann.

Embodiments of the invention are explained in more detail below with reference to the drawing; show it

Figure 1:

schematically a two-stage dryer for use in a painting system for vehicle bodies;

Figure 2:

a schematic section of a catalytic radiator, as used in the dryer of Figure 1;

Figure 3:

2 in combination with a pre-mixer, which can optionally be used in the dryer shown in FIG. 1.

Reference is first made to FIG. 1. The total The dryer provided with the reference number 1 comprises a dryer Housing 2 with an outer wall 2a and an inner wall 2 B. The inner wall 2b of the housing 2 encloses one Drying room 3 by a device 4, z. Legs Partition, in two air-technical separated Sub-rooms 3a and 3b is divided. Freshly painted Vehicle bodies are not shown in the drawing shown locks, coming from the left, into the sub-area 3a by means of a likewise not shown Conveyor system introduced by this through a the device 4 provided lock in the subspace 3b transferred and leave the housing 2 of the dryer 1 by another not shown in the drawing Lock.

In the inner wall 2b of the housing 2, preferably both in their side walls and in the ceiling wall, several catalytic emitters 5 are used, such that they with their radiant surface the sub-rooms 3a and 3b of the drying room 3 are facing. The construction method this catalytic emitter 5 is shown in the schematic figure 2 out. As this shows, each catalytic emitter includes 5 an outer housing 6 and an inner housing 7, between which a flow gap serving as air guidance 8 remains. The outer case 6 and the inner case 7 are on the lower in Figure 2, the drying room in operation 3 facing side open.

The inner housing 7 of the catalytic emitter 5 contains from top down a gas distribution device 9, in which a gas supply line 10 opens, an insulation layer 11, an electrical preheater 12 and one catalytically active layer 13, which on the in Figure 2 downward-facing side is exposed.

In the flow gap 8 between the outer housing 6 and the inner housing 7 opens an air supply nozzle 14th

The entire catalytic emitter 5 is by the choice of materials used designed to withstand high temperatures, therefore also required at operating temperatures of for example 250 to 300 ° C no cooling air.

As shown in Figure 1, that in sub-room 3a of the drying room 3 arranged catalytic emitters 5 via a line 15 and branch lines 15a, 15b connected to the corresponding ones Air supply connector 14 of the catalytic radiator 5 connected are supplied with supply air. This supply air can z. B. solvent-laden exhaust air from a dryer 1 assigned evaporation zone or slightly odorous Exhaust air from a cataphoretic dip painting system his.

The contained in the sub-room 3a of the drying room 3 Air can be drawn through a line 16 in which a blower 17 lies, circulate. Branches from line 16 a further line 18 leading to the air supply nozzle 14 in the second sub-room 3b of the drying room 3 arranged catalytic radiator 5 leads. That too Sub-space 3b is assigned a circulation line 19, in which is another blower 20. From the circulation line 19 leads an exhaust duct 21 to the outside atmosphere.

The dryer 1 described above works as follows:

At the start of operation, the catalytically active layers 13 of the different catalytic rays 5 with the help the electrical preheaters 12 to a temperature preheated from approx. 150 to 200 ° C, for catalytic Oxidation of the combustion gas is required. Now the catalytic emitters 5 in both sub-rooms 3a, 3b of the drying room 3 via the respective gas supply lines 10 combustion gas supplied. This is in the corresponding catalytic emitter 5 by the gas distribution device 9 over the entire flow cross-section evened out, penetrates the insulating layer 11, which also because of their flow resistance a contribution to the equalization of the gas flow performs, and then reaches the preheated catalytic active layer 13.

At the outer, directed downwards in Figure 2 Surface meets the supply air, which over the respective Air supply pipe 14 and the flow gap 8 flowed and the edge flanges 22 bent inwards of the outer housing 6 a main flow direction in parallel obtained to the surface of the catalytically active layer 13 has on the combustion gas. It now finds the catalytic one Reaction with the combustion gas flowing out flat instead, with the catalytically active layer on an operating temperature of about 600 ° C is heated. The hot outer surface of the catalytically active layer 13 now emits infrared radiation in the long-wave Area. After reaching the operating temperature the electrical preheating 12 switched off.

The airways are shown in detail in FIG Dryer 1 as follows:

The supplied via line 15, for example from the evaporative zone and with organic substances polluted air gets into the catalytic radiators 5, the are assigned to the left subspace 3a in FIG. 1, in Contact with the combustion gases and reacts with them catalytically. It also becomes a part of this Organic impurities oxidized in air. The air in sub-room 3a is blown with the help of the blower 17 circulated and an air stream drawn off via line 18, the - converted to the same temperature - that Air volume corresponds to that through the line 15 is supplied.

The air circulated by the fan also overflows the object to be dried and heats it convectively. The amount of circulated air also determines whose temperature is the amount of energy transferred.

The catalytic emitters 5 transfer to the one to be dried Subject energy in the form of infrared radiation. This Amount of energy is by the amount of combustion gas that is supplied through the lines 10, and through the Distance between the object to be dried and the Catalytic radiators 5 determined.

According to the object to be dried, by Varying the amount of recirculated air and by setting the power the catalytic radiator 5 and by the distance between the object to be dried and the catalytic emitters 5 the ratio in which the heat input is varied by radiation and by convection. there Two borderline cases are conceivable: a very small one Distance between object and catalytic emitter and very low circulation of low temperature air approaches the portion of the radiation 100% heat transfer. With a very large distance between Object and catalytic emitters 5 and lower power the catalytic radiator 5 as well as with a high amount of circulating air and high The proportion of convective air temperature approaches 100% heat transfer.

Which in this way is somewhat organic Substances freed air is via the line 18 Catalytic emitters 5 supplied, the one on the right in FIG Subspace 3b of the drying room 3 are assigned. There similarly finds a reaction of the carried organic impurities on the catalytic layers 13 instead. The result is that by means of the blower 20 and circulated air in the subspace via line 19 3b of the drying room largely from organic substances is exempt so that the discharged via line 21 Air can be released into the outside atmosphere can.

Of course it is possible to change the number of cleaning stages, the air spaces separated from each other and circulators, if necessary increase to a higher degree of purification of the air achieve.

In Figure 3, a second type is shown as the Catalytic radiator 5 can be supplied with supply air. The catalytic emitter 5 of FIG. 3 coincides with that of Figure 2 are identical. Via the gas supply line 10, however, does not become a pure combustion gas, but a mixture of polluted supply air and combustion gas inside the catalytic emitter 5 initiated. This mixture is in a premixer 23 produced, the combustion gas via a first line 24 and via a second line 25 containing pollutants Exhaust air is supplied.

The lines are installed in the dryer 1 of FIG. 1 25 the premixer 23 the catalytic emitter 5, the assigned to the left subspace 3a of the drying room 3 are parallel to the branch lines 15a, 15b to the Line 15 connected, through which the contaminated supply air comes from the evaporation zone while the ducts 25, which is the right in FIG. 1 subspace 3b of the drying room 3 are assigned, parallel to the lines 18a, 18b leading to the already pre-cleaned air Line 18 are connected.

The ratio in which the combustion gas 24 in the premixers 23 is mixed with air set that according to the pollution of the Air catalytic oxidation as complete as possible the pollutants take place. In a corresponding way the proportion of the polluted air via line 25 to the premixer and what proportion over the air supply nozzle 14 is supplied to the catalytic emitter 5.

Claims (10)

Dryer for objects, in particular for vehicle bodies, with a) a housing in which a drying chamber accommodating the objects is formed; b) a connection for supply air; c) a connection for exhaust air; d) at least one catalytic emitter, which in turn has: da) at least one connection for combustion gas; db) a catalytically active layer, to which the combustion gas is supplied; dc) at least one connection for combustion air, which is connected to the catalytically active layer via an air duct; characterized in that e) the connection (15) of the dryer (1) for supply air is connected exclusively to the connection (14) of the catalytic radiator (5) for combustion air, such that, apart from inevitable leakages in the housing (2), the entire supply air as combustion air via the Catalytic radiator (5) is guided; f) the catalytic radiator (5) is heat-resistant in the sense that it does not require air cooling. Dryer according to claim 1, characterized in that the catalytic radiator (5) has a connection (14) through which only supply air is supplied to it. Dryer according to Claim 1 or 2, characterized in that the catalytic emitter (5) has a connection (10) which is connected to a premixer (22) in which the combustion gas and supply air are mixed with one another. Dryer according to one of the preceding claims, characterized in that it has at least one blower (17) with which the air in the drying chamber (3) can be circulated. Dryer according to one of the preceding claims, characterized in that it is constructed in several stages, each stage being designed in the manner described in one of claims 1 to 4 and the connection for exhaust air of the upstream stage in each case with the connection for supply air each downstream level is connected. Method for operating a dryer for objects, in particular vehicle bodies, in which a) the objects to be dried are placed in a drying chamber in the housing of the dryer; b) the objects to be dried are exposed in the drying room to infrared radiation which is generated by a catalytic radiator, the catalytically active layer of which is supplied with combustion gas and combustion air; c) supply air is constantly supplied to the drying room and air is extracted;
characterized in that d) the entire supply air supplied to the drying room (3), apart from inevitable leaks in the housing (2) of the dryer (1), is conducted as combustion air via the catalytically active layer (13) of the catalytic radiator (5); e) a catalytic radiator (5) is used which is heat-resistant in the sense that it does not require cooling. Method according to claim 5, characterized in that at least part of the supply air is mixed with the combustion gas before it enters the catalytic emitter (5). A method according to claim 6 or 7, characterized in that the exhaust air removed from a first stage of the dryer is supplied to at least one downstream stage of the dryer as supply air. Method according to one of claims 6 to 8, characterized in that the objects to be dried are additionally heated convectively by a circulated air stream. Method according to Claim 9, characterized in that the ratio of the heat introduced into the objects to be dried by radiation and by convective heating is variable.

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