DE102007025760A1 - Dryer for drying or heating coated workpieces, has infra-red (IR) heating device mounted in drying chamber - Google Patents

Abstract

A dryer is equipped with a drying chamber (34) in which is provided an infra-red (IR) heating device (14) provided with a housing (16) which has at least one wall surface (22) which at least surrounds one cavity (18) for IR-heating of a workpiece (20) therein. A least one burner (24) is provided the exhaust gasses of which flow into an exhaust gas duct (26) joined with at least one wall surface (22).

Description

The The invention relates to a dryer with a drying chamber for drying or burning in coated workpieces. This can be about Lacquer layers or powder layers act.

dryer in paint shops are generally with burners (oil / gas) or electrically heated and operated with circulating air, so that a sufficiently uniform temperature distribution guaranteed within the drying chamber is. This is dependent In some cases a considerable air circulation is necessary from the mass throughput, to a sufficiently high temperature stability for the baking process or to ensure the drying process. This means the consumption of considerable amounts of energy. To fast Preheating / heating In the dryer, electric or gas infrared radiators are additionally used. The latter release gas into the dryer over the surface, which is disadvantageous for many Coating materials is.

Of the Invention is based on the object, an improved dryer to create, which heats up quickly and a reduced energy demand has.

These The object is achieved by a Dryers with a drying chamber dissolved in an IR heater is provided, which is a housing having at least one wall surface at least a cavity for IR heating encloses a workpiece received therein, with at least one burner whose flue gases enter a flue gas duct stream, which is in communication with the at least one wall surface, and with a fan for circulation the atmosphere inside the drying chamber.

The Invention is completely solved in this way.

According to the invention the workpieces in the drying chamber first heated by an infrared heater and then inside the drying chamber dried with fan support. The IR heater is heated by a burner whose flue gases into a flue gas duct stream, the one with at least one wall surface communicates to the workpiece by infrared radiation to warm up.

By the upheaval the atmosphere within the drying chamber a uniform temperature distribution is ensured. However, since the heating of the workpiece surfaces is largely done by the IR heater is a significantly reduced Circulating required by the fan.

The Circulating inside the drying chamber can be compared to conventional dryers clearly be reduced because the main heat source, the IR heater, little or no recirculation required.

Of the Flue gas duct can either directly over a wall surface as a heating surface serve to IR heater of the workpiece or can through at least one opening of Flue gas to be flowed through from the flue gas duct, so at least the a wall surface, the the workpiece surrounds, heat up.

For this can the flue gas duct via openings with the wall surfaces which surround the workpiece.

The wall surface the flue gas duct can preferably also be thermally insulated and with a plurality of openings be designed as a flue gas distributor.

hereby the IR heating of the wall surfaces surrounding the workpiece is improved.

According to one Another embodiment of the invention, the flue gas duct opens into a Heating chamber extending along the at least one wall surface, the cavity for workpiece holder encloses.

Preferably the flue gas duct has a wall designed as a heating surface, the above a variety of openings is connected to the heating chamber.

According to one Another embodiment of the invention, the heating chamber is in sections divided, each with openings connected to the flue gas duct.

in this connection the sections are preferably each with an exhaust passage coupled.

On this way can provide an intense and uniform IR radiant heating of the the workpiece facing wall surfaces be achieved.

According to one further execution the invention opens the flue gas channel into a plurality of tubes, along the at least a wall surface run.

Also by such a flue gas guide Tubes can achieve IR radiant heating for the workpiece become.

As far as a heating chamber is provided, which is connected to the flue gas duct, the Heating chamber preferably be divided by baffles, which preferably extend transversely to the at least one wall surface.

On this way, a plurality of subsections can be formed, wherein preferably at least one section meandering is divided.

On This way, an intense and even heat supply to the workpiece facing walls reached the heating chamber.

In alternative version The invention is the object of the invention by a with a Drying chamber solved, in which an IR heater is provided with at least one Burner, whose flue gases flow into a flue, with Radiation tubes for IR heating of a workpiece, with the flue gas channel to the flow connected with flue gases, and with a fan for circulating the the atmosphere inside the drying chamber.

Also In this way, the object of the invention is completely solved.

Also an IR heater with radiant tubes made of flue gases flows through the burner are possible an effective heating of a workpiece.

According to one Continuing the aforementioned execution are the radiation tubes reflectors for the reflection of IR radiation towards the workpiece assigned.

hereby the efficiency of the IR heater is improved.

Even though in many cases in principle the heating power of the IR heater is sufficient to the desired drying temperature within the drying chamber, it is advantageous in some cases to provide an additional heater within the drying chamber.

So can the workpieces after preheating by the IR heater either on one by IR heating reached temperature or heated to a higher operating temperature become.

On this way you can also high operating temperatures, which are for example at 180 to 200 ° C, be achieved particularly fast and energy-saving. The IR heater can for example, a preheating of the workpieces to 120 to 150 ° C cause while by the additional heating in connection with the fan inside the drying room a higher Operating temperature of for example 180 to 200 ° C complied with can be. Due to the IR heater can fast preheating the workpieces especially in continuous operation, while by the additional heating in conjunction with the fan the necessary constancy of the higher operating temperature is guaranteed.

Even though in principle unlike known burners used for infrared heating be, no flue gas circulation is necessary, it may be advantageous in some cases, in addition to one Fan for circulation to use the flue gases.

Of the Dryers can basically be designed as a batch dryer. Preferably, the dryer However, designed as a continuous dryer and has a conveyor for advancement of workpieces through the IR heater and through the drying chamber. there are basically any type of construction conceivable, such as an execution as overhead conveyor, as floor conveyor, as a belt conveyor, roller conveyor, circular conveyor or Power & Free Conveyor.

According to one further execution the invention, the flue gases are guided in an exhaust duct, the a further system component is supplied for heating.

On this way, the relatively large waste heat of the flue gases can be optimal and energy-saving used to heat other parts of the system. For this For example, a heat exchanger can be used be used to perform about a domestic water heating. Furthermore can the flue gases are fed to another dryer that is insensitive against flue gases, which is usually high quality paint jobs undesirable are. It may be about a stick water dryer or act a KTL dryer. Possibly. may also be parts of the flue gases be returned to the dryer itself, as far as the coatings concerned, which are treated in the dryer are insensitive to the influence of flue gas. Likewise can the flue gases heat a downstream heat exchanger, the Additional heating of the drying chamber is used.

According to one further execution The invention provides a controller by means of which the controller the performance of the burner in dependence from the operating temperature in the drying chamber.

In this way, an optimal match between burner performance and operating temperature within the drying chamber guaranteed become.

According to one further execution The invention, the heating chamber and / or the workpiece facing away Parts with a thermal insulation are provided.

hereby the effect of IR heating is improved.

It it is understood that the above and the following yet to be explained features of the invention not only in the respective specified combination, but also usable in other combinations or in isolation, without departing from the scope of the invention.

Further Features and advantages of the invention will become apparent from the following Description of preferred embodiments with reference to the drawing. Show it:

1 a schematic representation of a dryer according to the invention with an IR heater;

2 a schematic longitudinal section through the IR heater according to 1 in an enlarged view;

3 an enlarged cross section through the IR heater according to 1 ;

4 a schematic representation of an IR heater in combination with a bottom conveyor;

5 a schematic representation of an IR heater with a roller or chain conveyor;

6 a modified embodiment of the IR heater according to 1 in which an IR irradiation also takes place from above;

7 a schematic representation showing the coupling of an IR heater with other system components of a paint shop for waste heat utilization of the flue gases of the burner;

8th a modified embodiment of an IR heater;

9 a longitudinal section through the flue gas channel according to 8th ;

10 a cross section through the flue gas channel according to 8th with associated radiation tubes;

11 a modification of the embodiment according to 8th with additional wall reflector; and

12 a schematic representation of a tube reflector that can be used for the radiation tubes to improve the radiation effect.

In 1 an inventive dryer is shown schematically and in total with the numeral 10 designated. The dryer 10 has a housing 12 on, which is provided with a thermal insulation and within which a drying chamber 34 is defined. Inside the drying chamber 34 is an IR heater 14 for preheating workpieces 20 intended. Inside the drying chamber 34 is also a sponsor 46 arranged through the workpieces 20 through the IR heater 14 through and in several serpentine paths through the drying chamber 34 can be moved through. The dryer 10 is formed in the case shown here as a continuous dryer. The atmosphere inside the drying chamber 34 can by a fan 32 be circulated out of the drying chamber 34 in the direction of the arrows 42 Air sucks and these in a ventilation duct 36 promotes. The ventilation duct 36 is through a partition 21 from the drying chamber 34 separated and has a heater 40 on. After heating by the heater 40 the atmosphere thus heated passes through outlet nozzles 38 or slots back into the drying chamber 34 one to the workpieces 20 to heat to operating temperature, which may be, for example, about 180 to 200 ° C.

The IR heater 14 serves to preheat the workpieces 20 to a temperature of about 120 ° C. Further heating of the workpieces 20 to the operating temperature is provided by the heater 40 , In the IR heater 14 is a cavity 18 provided by wall surfaces 22 is limited, which are arranged so that a U-shaped cross-section results, through which the workpieces 20 by means of the conveyor 46 can be promoted through. The cross section of the cavity 18 is due to the shape of the workpieces 20 customized. For heating the IR heater 14 serves a burner 24 , whose flue gases in a heat-insulated flue gas duct 26 stream. The flue gas channel 26 has a wall 28 on, which is parallel to the bottom wall of the cavity 18 runs. This wall 28 is from a variety of openings 30 interspersed, through which the flue gases into a heating chamber 29 pass through the wall surfaces 22 to the cavity 18 is limited. The wall 28 is designed as a flue gas distributor. The through the wall 28 through the openings 30 passing smoke gases flow around so immediately the wall surfaces 22 and heat them up. Preferably, the wall 28 thermally insulated.

The power of the burner 24 is preferably not regulated or by means of a controller 25 depending on the temperature inside the drying chamber 34 regulated. This is in the drying chamber 34 a temperature sensor 27 provided by a line 31 with the controller 25 is coupled, of which the burner power is controlled.

As a result of the IR heater 14 , which preheats the workpieces to about 120 ° C, is a very rapid heating of the workpieces 20 guaranteed to the operating temperature of about 180 to 200 ° C. Furthermore, as a result of the IR heater 14 only a relatively small air circulation within the drying chamber 34 necessary to ensure a uniform air circulation or operating temperature within the drying chamber 34 sure. In this way, the amount of circulating air or the power consumption compared to conventional dryers is significantly reduced.

The structure of the IR heater 14 will be explained in more detail below.

The IR heater 14 according to 1 is in 2 and 3 shown enlarged.

As previously mentioned, the flue gases of the burner flow 24 in the flue gas duct 26 and over openings 30 in the sidewall 28 in the heating chamber 29 , The heating chamber 29 is now in individual sections 48 . 50 . 52 . 54 divided. The sections 48 . 50 . 52 . 54 are each through baffles 58 . 60 divided so that from the wall 28 opposite openings 62 from a meandering flow in the direction of the arrows 66 until it exits to an exhaust duct 56 results.

By the division into the sections 48 . 50 . 52 . 54 and the arrangement of the baffles 58 . 60 a better flue gas distribution and thus a more uniform IR heating is achieved.

In this way, a uniform heating of the lateral wall surfaces 22 of the cavity 18 achieved.

The burner 24 In the case shown here, without a fan, the flue gases are circulated. Compared to conventional burners with oil or gas burners is the burner 24 designed with a lower Heizflächenbelastung so that it can be operated without direct forced cooling. The flue gas channel can be so handy around the cavity 18 be unfolded around, resulting in a significantly improved efficiency for direct IR heating of workpieces 20 results.

The housing 16 The IR heater is outwardly preferably by a heat insulation 57 thermally insulated. Likewise, the wall penetrated by openings 28 preferably thermally insulated.

In The following figures will be corresponding to corresponding parts Reference numerals used.

Another embodiment of an IR heater is in 4 represented and in total with 14a designated. This is in principle a vertically upturned arrangement in comparison to 1 , Instead of an overhead conveyor 46 Here is a bottom conveyor 46 provided while burner and flue 26 arranged above it. The wall surfaces 22 of the cavity 18 turn through the through the openings 30 heated by passing flue gases.

Another variation of the IR heater is in 5 represented and in total with 14b designated.

Again, the IR heating of the workpieces is done 20 from above. Instead of a floor conveyor 46 Here, a roller or belt conveyor is provided.

Another embodiment of the IR heater is in 6 represented and in total with 14c designated.

The only difference to the execution according to the 2 and 3 is that the case 16 the cavity 18 partially encloses also in the ceiling area, so that additionally result in the ceiling IR heating surfaces. Overall, this results in even more uniform heating of workpieces 20 by the conveyor designed as a hanging conveyor 46 be promoted through.

In 7 is shown schematically how the flue gases of the burner of the IR heater 14 can be used to heat other plant components in a paint shop.

A first exhaust duct 56 into which the flue gases of the burner are introduced, is with a heat exchanger 78 coupled to heat, for example, a pretreatment plant or service water.

Another exhaust duct 56 is with another dryer 80 coupled to heat it directly. This may be, for example, a KTL dryer or an adhesive dryer, which are insensitive to flue gases. The flue gas can also be due to a Lufterhit zer (heating 40 according to 1 ).

Another modification of the IR heater is in the 8th . 9 . 10 represented and in total with 14d designated.

This is on a the workpieces 20 enclosing housing omitted. There are radiation tubes 82 built in by flue gas from the heating chamber 29 be flowed through and in individual sections meander parallel to the side surfaces of the workpiece 20 extend and each into the flue gas channel 56 lead. Because on between the radiant tubes 82 and the workpiece 20 arranged wall surfaces is omitted, this results in a more direct radiant heating than in the embodiment according to the 2 and 3 , To improve the efficiency are the radiation tubes 56 preferably additionally surrounded by curved reflectors or surface reflectors. This may be about tube reflectors 86 according to 12 act.

Instead, a wall reflector can also be used 84 as in the modified embodiment according to 1 be provided with a total of 14e designated IR heater shows.

At the wall reflector 84 or the tube reflectors 86 For example, it can be reflective surfaces on the inside or even reflectors with a rough textured surface.

Claims (19)

Dryer with a drying chamber ( 34 ), in which an IR heater ( 14 . 14a . 14b . 14c ), which is a housing ( 16 ), the at least one wall surface ( 22 ) having at least one closed cavity ( 18 ) for IR-heating a workpiece received therein ( 20 ), with at least one burner ( 24 ), whose flue gases into a flue gas duct ( 26 ) flowing with the at least one wall surface ( 22 ) and with a fan ( 32 ) for circulating the atmosphere within the drying chamber ( 34 ). Dryer according to claim 1, wherein the flue gas duct ( 26 ) via openings ( 30 ) with the wall surfaces ( 22 ). Dryer according to claim 1 or 2, wherein the flue gas duct ( 26 ) in a heating chamber ( 29 ), which extends along the at least one wall surface ( 22 ) and through at least one opening ( 30 ) with the flue gas channel ( 26 ) connected is. Dryer according to claim 3, wherein the wall surface ( 22 ) is thermally insulated and with a plurality of openings ( 30 ) is designed as a flue gas distributor. Dryer according to claim 3, wherein the flue gas duct ( 26 ) as a heating surface ( 28 ) formed wall which via a plurality of openings ( 30 ) with the heating chamber ( 29 ) connected is. Dryer according to claim 3, 4 or 5, wherein the heating chamber ( 29 ) into subsections ( 48 . 50 . 52 . 54 ), each via openings ( 62 . 30 ) with the flue gas channel ( 26 ) are connected. Dryer according to Claim 6, in which the sections ( 48 . 50 . 52 . 54 ) each with an exhaust passage ( 56 ) are coupled. Dryer according to one of the preceding claims, wherein the flue gas duct ( 26 ) into a plurality of radiation tubes ( 82 ), which along the at least one wall surface ( 22 ). Dryer according to one of claims 3 to 8, wherein in the heating chamber ( 29 ) Baffles ( 58 . 60 ) are arranged to the subdivision, which preferably transversely to the at least one wall surface ( 22 ). Dryer according to one of claims 3 to 8, wherein the heating chamber ( 29 ) into at least one subsection ( 48 . 50 . 52 . 54 ) is divided meandering. Dryer with a drying chamber ( 34 ), in which an IR heater ( 14e . 14f ), with at least one burner ( 24 ), whose flue gases into a flue gas duct ( 26 ), with radiant tubes ( 82 ) for IR-heating a workpiece, which with the flue gas channel ( 26 ) are connected to the flow of flue gases, and with a fan ( 32 ) for circulating the atmosphere within the drying chamber ( 34 ). Dryer according to claim 11, wherein the radiation tubes ( 82 ) Reflectors ( 84 . 86 ) for reflection of IR radiation in the direction of the workpiece ( 20 ) assigned. Dryer according to one of the preceding claims, with an additional heating ( 40 ) within the drying chamber ( 34 ). Dryer according to one of the preceding claims, at the IR heater a fan for forced cooling having the flue gases. Dryer according to one of the preceding claims, with a conveyor ( 46 ) to promote of workpieces through the IR heater and through the drying chamber ( 34 ), which is preferably designed as a hanging conveyor, floor conveyor, belt conveyor, roller conveyor, circular conveyor or Power & Free conveyor. Dryer according to one of the preceding claims, in which the flue gases are introduced into an exhaust gas duct ( 56 ), which is connected to a further plant component ( 40 . 78 . 80 ) is coupled to warming. Dryer according to Claim 16, in which the further installation component is another dryer ( 80 ), such as an adhesive dryer or a KTL dryer, to a heat exchanger ( 78 ) or an additional heating ( 40 ) for the drying chamber ( 34 ). Dryer according to one of the preceding claims, with a controller ( 25 ) for controlling the power of the burner ( 24 ) as a function of the operating temperature in the drying chamber ( 34 ). Dryer according to one of the preceding claims, in which the heating chamber ( 29 ) and / or the workpiece ( 20 ) facing away from parts with a thermal insulation ( 57 ) are provided.