EP2531796B1 - Device for drying articles - Google Patents

Description

1. a) einem Trockentunnel, welcher in einem isolierten Gehäuse angeordnet ist;
2. b) einer Mehrzahl von Tunnelabschnitten, welche jeweils wenigstens einen Luftauslass und wenigstens einen Lufteinlass umfassen;

wobei

• c) jedem Tunnelabschnitt ein Heizaggregat zugeordnet ist, welchem Luft aus dem wenigstens einen Luftauslass des Tunnelabschnitts zuführbar und in welchem eine heiße Primärgasströmung erzeugbar ist;
• d) das heiße Primärgas in einen Umwälzluft-Wärmetauscher des Heizaggregats leitbar ist, in dem Umwälzluft durch heißes Primärgas erhitzbar ist, die dem Tunnelabschnitt wieder in einem Kreislauf über den wenigstens einen Lufteinlass zuführbar ist;
• e) das Heizaggregat eine Verteilereinrichtung umfasst, durch welche die aus einem Tunnelabschnitt austretende Luft in einen Umwälzluftstrom und einen Abluftstrom aufteilbar ist;
• f) das Heizaggregat eine thermische Nachverbrennungseinrichtung umfasst, welcher die Abluft zuführbar ist und durch welche die heiße Primärgasströmung erzeugbar ist.

The invention relates to a device for drying objects, in particular of vehicle bodies, with

1. a) a drying tunnel, which is arranged in an insulated housing;
2. b) a plurality of tunnel sections, each comprising at least one air outlet and at least one air inlet;

in which

• c) each tunnel section is assigned a heating unit to which air can be supplied from the at least one air outlet of the tunnel section and in which a hot primary gas flow can be generated;
• d) the hot primary gas can be conducted into a circulating air heat exchanger of the heating unit, in which circulating air can be heated by hot primary gas, which can be supplied to the tunnel section again in a circuit via the at least one air inlet;
• e) the heating unit comprises a distributor device, by means of which the air emerging from a tunnel section can be divided into a recirculating air stream and an exhaust air stream;
• f) the heating unit comprises a thermal post-combustion device to which the exhaust air can be supplied and through which the hot primary gas flow can be generated.

Such from the market and from the DE 10 2008 012 792 A1 known dryers are used in particular for drying freshly painted vehicle bodies, but also for drying other objects. Such dryers are heated by, among other things, sucking air from short tunnel sections, which are short in relation to the total length of the drying tunnel, heated in a heating unit by means of a heat exchanger and recirculated to the corresponding tunnel section. When drying freshly painted vehicle bodies, the air taken from the tunnel section is mainly loaded with solvent, which is released during the drying process. In addition, in this air are found when drying the vehicle body liberated coating components; However, for the sake of simplicity, only solvent-containing air or exhaust air will be discussed below.

The disposal of the solvent-containing exhaust air takes place in other known systems in a separate and independent of the heating circuits system. For this purpose, the solvent-containing exhaust air to be disposed of is sucked off at a central outlet of the drying tunnel and fed to a thermal or regenerative afterburning, in which the solvents are burned. Optionally, the afterburning heat exchanger downstream, in which fresh air is heated by means of the resulting hot combustion gases. This hot fresh air is then fed to the drying tunnel, whereby this is also heated.

However, the lines to lead the solvent-containing exhaust air for afterburning, there are quite long. Since a complex isolation of these lines is required, the resulting costs for the system are relatively high overall.

In addition, there are relatively large energy losses, since the hot, clean combustion gases - apart from their use in the fresh air heat exchanger - are largely released unused via a fireplace to the environment.

The afterburning and thus the disposal of the solvent-containing exhaust air is integrated in the device of the type mentioned in the heating unit and only a portion of the tunnel section removed air recirculated as recirculated air back into the tunnel section. The hot combustion gases form at least in part the hot primary gas flow which is used to heat the recirculation air. As a result, the energy contained in the hot combustion gases is effectively used to heat the dryer.

Thus, can be dispensed with an external afterburning. On the one hand, this lowers the construction costs and, on the other hand, allows a more compact design of the dryer. In addition to the smaller space requirement of the dryer thereby thermal losses are reduced.

It is an object of the invention to provide a device of the type mentioned, in which in particular the energy balance is further improved.

• g) das Heizaggregat einen Abluft-Wärmetauscher umfasst, in welchen heißes Primärgas leitbar ist und in dem die Abluft vor Erreichen der Nachverbrennungseinrichtung durch heißes Primärgas erhitzbar ist;
• h) die Menge von heißem Primärgas, die dem Abluft-Wärmetauscher zugeführt wird, mittels einer ersten Regulierklappe einstellbar ist;
• i) die erste Regulierklappe in einer Bypass-Leitung angeordnet ist, durch welche heißes Primärgas an dem Abluft-Wärmetauscher vorbei geleitet werden kann.

This object is achieved in a device of the type mentioned in that

• g) the heating unit comprises an exhaust air heat exchanger, in which hot primary gas is conductive and in which the exhaust air is heated by hot primary gas before reaching the afterburner;
• h) the amount of hot primary gas that the exhaust air heat exchanger is supplied, is adjustable by means of a first regulating flap;
• i) the first regulating flap is arranged in a bypass line through which hot primary gas can be conducted past the exhaust air heat exchanger.

Characterized in that the heating unit comprises an exhaust air heat exchanger in which hot primary gas is conductive and in which the exhaust air is heated by hot primary gas before reaching the afterburner, the exhaust air can be preheated prior to their combustion. In this way, the energy required by the burner can be reduced, which is required to heat the solvent-containing exhaust air from its initial temperature, with which it reaches the burner, to the combustion temperature.

Since the amount of hot primary gas supplied to the exhaust air heat exchanger is adjustable by means of a first regulating flap located in a bypass line through which hot primary gas can be passed past the exhaust air heat exchanger, the extent of preheating the exhaust air can be adjusted.

In practice, it has proved to be advantageous if the afterburner is a gas burner.

In this case, it is particularly favorable in view of the air budget of the dryer when the gas burner is operable without the supply of additional air. In this case, the hot primary gas flow consists solely of hot combustion gases, which are thus fully and effectively used to heat the recirculation air.

It is of particular advantage if the gas burner is a surface burner. A surface burner offers a good burning performance and does not require any additional air supply.

If hot primary gas, which has flowed through the exhaust air heat exchanger, can be supplied to the circulating-air heat exchanger, the hot combustion gases can be used twice and thus particularly effectively. They then serve on the one hand for preheating the exhaust air and on the other hand for heating the circulating air.

In the event that the temperature of the coming from the exhaust heat exchanger hot primary gas is not sufficient to heat the circulating air to the desired temperature, it is advantageous if the circulating air heat exchanger hot primary gas from a section of the bypass line can be fed downstream the first regulating flap is arranged. In this way, the recirculating air heat exchanger is not or only very little cooled primary gas can be supplied.

If the section of the bypass line is arranged between the first regulating flap and a second regulating flap, the amount of primary gas for the circulating air heat exchanger can be regulated via the second regulating flap, without the position of the first regulating flap and of the exhaust air heat exchanger passing by guided part of the primary gas flow would have to be changed.

If the heating unit comprises a fresh air heat exchanger in which hot primary gas is conductive and in the fresh air can be heated by hot primary gas, the primary gas can also be used to heat any fresh air required for dryer heating.

In this case, the primary gas flow can be used in triplicate if the heating unit comprises a fresh air heat exchanger in which hot primary gas can be conducted, which has flowed through the exhaust air heat exchanger and the recirculating air heat exchanger. Alternatively, the fresh primary gas supplied to the fresh air heat exchanger may have previously passed through only the exhaust air heat exchanger or the recirculating air heat exchanger.

In order to control the heating of the fresh air, it is advantageous if the fresh air heat exchanger hot Primary gas from a portion of the bypass line can be fed, which is arranged downstream of the second regulating flap.

Hot fresh air is supplied in particular to an inlet lock area arranged at the entrance of the drying tunnel and / or to an outlet lock area arranged at the exit of the drying tunnel, from where the hot fresh air can flow into the drying tunnel.

Figur 1

ein schematisches Layout eines Trockners mit einem mehrere Tunnelabschnitte umfassenden Trockentunnel, denen jeweils ein Heizaggregat zugeordnet ist;

Figur 2

ein in Figur 1 gezeigtes Heizaggregat in vergrößertem Maßstab.

An embodiment of the invention will be explained in more detail with reference to the drawing. In this shows:

FIG. 1

a schematic layout of a dryer with a tunnel tunnel comprising several tunnel sections, each associated with a heating unit;

FIG. 2

a in FIG. 1 shown heating unit in an enlarged scale.

In FIG. 1 10 is a total of 10 a dryer comprising an insulated housing 12 in which a drying tunnel 14 is arranged. The drying tunnel 14 comprises a plurality of tunnel sections 16.1, 16.2, ..., 16.n arranged one behind the other.

The dryer 10 is used in particular for drying freshly painted vehicle bodies, but can also be used in its basic concept for drying any objects.

The vehicle bodies enter the dryer 10 at one end of the dryer 10 on a conveyor system (not shown), first pass into an inlet lock 18 and from there into the drying tunnel 14. The vehicle bodies finally exit the dryer 10 through an outlet lock 20 in the dried state, after they have passed through the tunnel sections 16.1, 16.2, ..., 16.n.

Each tunnel section 16.1, 16.2,..., 16.n has an air outlet 22 and an air inlet 24.

Each tunnel section 16.1, 16.2, ..., 16.n is also assigned its own heating unit 26, of which in FIG. 1 only the heating units 26 of the tunnel sections 16.1 and 16.2 can be seen.

By means of the heating units 26 can be heated from the respective tunnel section 16.1, 16.2, ..., 16.n sucked air and be returned in a cycle through the respective air inlet 24 in the corresponding tunnel section 16.1, 16.2, ..., 16.n. The returned air is e.g. guided on non-specifically illustrated nozzles on the vehicle bodies to be dried.

In this way it is possible to maintain different temperatures in the tunnel sections 16.1, 16.2,..., 16.n, as is most favorable for the drying process in each case.

The structure and operation of the heating units 26 will now be described using the example of the tunnel section 16.1 associated heating unit 26. The remaining heating units 26 are constructed accordingly and work in the same manner.

When drying a vehicle body located in the tunnel section 16.1, solvents are released, inter alia, so that an atmosphere of solvent-containing air prevails in the tunnel section 16.1.

The heating unit 26 comprises a fan 28 which is arranged in a line 30 which is connected to the air outlet 22 of the tunnel section 16.1, so that solvent-containing air can be sucked out of the tunnel section 16.1. This solvent-containing air is usually between about 140 ° C and 220 ° C hot.

The temperatures specified below relate to a drying process and a air balance, as they usually occur during drying of cataphoretic dip-coated vehicle bodies, for example. Depending on the type of varnish used, deviations upwards and downwards are possible accordingly.

Hereinafter, it is assumed that the solvent-containing air in the tunnel section 16.1 is about 200 ° C hot.

The line 30 opens downstream into a distribution device 32 which divides the sucked air into an exhaust air stream and a recirculating air stream.

The exhaust air flows from the distributor device 32 further through a line 34 into a heat exchanger coil 36 of an exhaust air heat exchanger 38. From there it flows into a combustion chamber 40 of a thermal afterburning device 42 with a gas burner 44, which is indicated by two arrows 46 and 48. As a gas burner 44, a burner is used in the embodiment described here, which can be operated without the supply of additional air. In practice, a surface burner has proven itself, as it is known in and of itself. Alternatively, however, it is also possible to use a forced-air burner, which must be supplied with air in a known manner for operation.

In the thermal afterburner 40, the Solvent in the exhaust air burned as much as possible, with the primary gas hot combustion gases produced at a temperature of about 700 ° C. These hot combustion gases are conducted via a feed line 50 to the exhaust air heat exchanger 38, where they heat the flowing through the heat exchanger coil 36 solvent-containing exhaust air to a temperature of about 400 ° C. At this temperature, the solvent-containing exhaust air consequently flows into the combustion chamber 40 of the thermal afterburning device 42.

The originally about 700 ° C hot combustion gases, however, are cooled in the exhaust air heat exchanger 38 and leave this via a first intermediate line 52 at a temperature of about 450 ° C.

About the intermediate line 52, the combustion gases are passed into a recirculating air heat exchanger 54. Whose heat exchanger coil 56 is traversed by the circulating air, which is supplied to the circulation air heat exchanger 54 via a line 56 from the manifold 32. The recirculating air coming from the distributor 32 at a temperature of about 200 ° C is heated by the hot combustion gases to a temperature of about 220 ° C, the hot combustion gases in turn cooling from about 450 ° C to a temperature of about 350 ° C.

The approximately 220 ° C hot recirculating air flows from the heat exchanger coil 56 of the recirculating air heat exchanger 54 in a return line 58, which leads to the air inlet 24 of the tunnel section 16.1. From there, the air is guided back to the vehicle bodies to be dried.

The now about 350 ° C hot combustion gases flow in the heating unit 26 from the circulation air heat exchanger 54 via an intermediate line 60 in a fresh air heat exchanger 62, whose heat exchanger coil 64 is fed via a fresh air line 66 with a fan 68. By the hot combustion gases flowing through the fresh air heat exchanger 62, the fresh air in the heat exchanger coil 64 is heated to about 200 ° C, wherein the hot combustion gases in turn cool to about 80 ° C.

The hot fresh air leaves the fresh air heat exchanger 62 via a line 70, which leads to the entrance lock 18. From there it enters the drying tunnel 14. The respective line 70 of heating units 26, which are arranged closer to the outlet lock 20, leads in a corresponding manner to the outlet lock 20, so that the hot fresh air can flow from there into the drying tunnel 14.

The cooled to 80 ° C combustion gases are passed through a discharge line 72 through a condensate 74 and from there to an exhaust chimney 76. About this get the purified combustion gases into the environment.

In the heating unit 26, the supply line 50 is connected to the exhaust air heat exchanger 38 with the discharge line 72 at the fresh air heat separator 62 via a bypass line 78 in connection. This has four bypass sections 78a, 78b, 78c and 78d, wherein between the first section 78a and the second section 78b, a first regulating flap 80, between the second section 78b and the third section 78c, a second regulating flap 82 and between the third section 78c and the fourth section 78d, a third regulating flap 84 is arranged.

The second bypass section 78b communicates via a conduit 86 with the intermediate conduit 52 between the exhaust air heat exchanger 38 and the recirculating air heat exchanger 54 in connection.

The third bypass section 78c communicates via a line 88 with the intermediate line 60 between the recirculating air heat exchanger 38 and the fresh air heat exchanger 54 in connection.

The above-explained operations and temperatures are achieved when the first regulating flap 80 is completely closed. In addition, it is assumed that the second regulating flap 82 and the third regulating flap 84 are also completely closed.

In this case, the hot combustion gases are completely guided out of the combustion chamber 40 into the exhaust air heat exchanger 38. The exhaust air is thereby preheated in the exhaust air heat exchanger 38 to 400 ° C, whereby relatively little energy is required for the gas burner 44 to heat the thus preheated exhaust air to the combustion temperature of 700 ° C.

However, since all the combustion gas cools in the exhaust air heat exchanger 38, the residual energy of the combustion gas is sufficient only to heat the 200 ° C hot circulating air in the circulation air heat exchanger 54 to 220 ° C. However, if the recirculating air heat exchanger requires more energy, either due to its design or to bring the recirculation air to a higher end temperature, the first regulating flap 80 can be opened.

A portion of the about 700 ° C hot combustion gases are thereby passed from the combustion chamber via the first two bypass sections 78a and 78b and the line 86 in the first intermediate line 52, where they mix with the coming of the exhaust air heat exchanger 38 combustion gases. The resulting combustion gas flow has a higher temperature than the combustion gases coming from the exhaust air heat exchanger 38. Thus, more energy is supplied to the recirculating air heat exchanger 54 for heating the recirculation air.

The proportion of the combustion gases flowing through the bypass line 78 into the intermediate line 52, and thus the energy supplied to the recirculating air heat exchanger 54 as a result of the mixing of the two gas streams, can be controlled via the opening degree of the first regulating flap 80.

In turn, the exhaust air in the exhaust air heat exchanger 38 is preheated when the first regulating flap 80 is opened no more to the extent as with closed first regulating flap 80. Thus, the power of the gas burner 44 must be increased to reach the combustion temperature in the combustion chamber 40, which leads to a higher consumption of fuel gas for the gas burner 44.

Similarly, the additional opening of the second regulating flap 82 in the bypass line 78 causes the hot combustion gases from the combustion chamber 40 to enter the intermediate conduit 60 where they heat the combustion gas stream coming from the recirculating air heat exchanger 54.

The combustion gases then flow at a higher temperature into the fresh air heat exchanger 62 than in the case of the closed second regulating flap 82.

The proportion of the combustion gases flowing through the bypass line 78 into the intermediate line 60, and thus the energy which is supplied to the fresh air heat exchanger 62 as a result of the mixing of the two gas streams, can here via the opening degree of the second regulating flap 82, optionally in conjunction with the opening degree of the first regulating flap 80, are controlled. The opening degree of the second Regulator flap 82 of course also affects the proportion of the combustion gases flowing through the bypass line 78, which reach the first intermediate line 52, which in turn affects the temperature of the result in the recirculation heat exchanger 54 combustion gas flow.

In addition, by opening the third regulating door 84, a part of the combustion gases flowing in the third bypass section 78c may be led past the fresh air heat exchanger 62 to the discharge line 72. As a result, the temperature of the combustion gas flow, which finally reaches the fresh-air heat exchanger 62, can again be set to lower temperatures than when the third regulating flap 84 is closed and the first and second regulating valves 80 and 82 are open.

Overall, through the bypass line 78 with the three regulating flaps 80, 82 and 84, the energy supplied to the circulating air heat exchanger 54 and the fresh air heat exchanger 62 in the form of hot combustion gases can be varied and adjusted.

In a modification 88 regulating valves are also provided in one or both lines 86, 88. In this case, a bypass flow path of combustion gases at the exhaust air heat exchanger 38 and the recirculating air heat exchanger 54 to the fresh air heat exchanger 62 or a bypass flow path of combustion gases on all three heat exchangers 38, 54 and 62 to the discharge line 72 are additionally possible ,

Each heating chamber 26 thus contributes both to the disposal of solvent-containing exhaust air and to heating of the dryer. The entrained by the exhaust pollutants are largely converted directly into usable energy in the heating chambers 26. In addition, the burner no additional fresh air must be supplied; for the combustion air or the primary gas flow directly the hot exhaust air is used.

It is also possible to retrofit existing dryers, as known from the prior art and which implement an external afterburning of the exhaust air, with heating chambers 26, as described above.

Claims (11)

1. A device for drying articles, in particular vehicle bodies, having

   a) a drying tunnel (14) which is arranged in an insulated housing (12);

   b) a plurality of tunnel sections (16.1, 16.2, ..., 16.n) which each comprises at least one air outlet (22) and at least one air inlet (24);

   wherein

   c) a heating unit (26), which can be supplied with air from the at least one air outlet (22) of the tunnel section (16.1, 16.2, ..., 16.n) and in which a hot primary gas flow can be generated, is associated with each tunnel section (16.1, 16.2, ..., 16.n);

   d) the hot primary gas can be directed into a circulating air heat exchanger (54) of the heating unit (26), in which circulating air can be heated by hot primary gas, which circulating air can be supplied to the tunnel section (16.1, 16.2, ..., 16.n) again in a circuit by way of the at least one air inlet (24);

   e) the heating unit (26) comprises a distributor device (32) by means of which the air exiting a tunnel section (16.1, 16.2, ..., 16.n) can be divided into a circulating air flow and an exhaust air flow;

   f) the heating unit (26) comprises a thermal afterburning device (42) to which the exhaust air can be supplied and by means of which the hot primary gas flow can be generated,

   characterised in that

   g) the heating unit (26) comprises an exhaust air heat exchanger (38) into which hot primary gas can be directed and in which the exhaust air can be heated by hot primary gas before it arrives at the afterburning device (42);

   h) the quantity of hot primary gas supplied to the exhaust air heat exchanger (38) can be adjusted by means of a first regulating flap (80);

   i) the first regulating flap (80) is arranged in a bypass line (78) by means of which hot primary gas can be guided to bypass the exhaust air heat exchanger (38).
2. A device according to Claim 1, characterised in that the afterburning device (42) is a gas burner.
3. A device according to Claim 2, characterised in that the gas burner (42) can be operated without a supply of secondary air.
4. A device according to Claim 3, characterised in that the gas burner (42) is a surface burner.
5. A device according to one of Claims 1 to 4, characterised in that the circulating air heat exchanger (54) can be supplied with hot primary gas which has flowed through the exhaust air heat exchanger (38).
6. A device according to Claim 5, characterised in that the circulating air heat exchanger (54) can be supplied with hot primary gas from a section (78b) of the bypass line (78) which is arranged downstream of the first regulating flap (80).
7. A device according to Claim 6, characterised in that the section (78b) of the bypass line (78) is arranged between the first regulating flap (80) and a second regulating flap (82).
8. A device according to one of Claims 1 to 7, characterised in that the heating unit (26) comprises a fresh air heat exchanger (62) into which hot primary gas can be directed and in which fresh air can be heated by hot primary gas.
9. A device according to one of Claims 1 to 8, characterised in that the heating unit (26) comprises a fresh air heat exchanger (62) into which hot primary gas can be directed, which has flowed through the exhaust air heat exchanger (38) and/or the circulating air heat exchanger (54).
10. A device according to Claim 8 or 9 with reference to Claim 7, characterised in that the fresh air heat exchanger (62) can be supplied with hot primary gas from a section (78c) of the bypass line (78) which is arranged downstream of the second regulating flap (82).
11. A device according to one of Claims 8 to 10, characterised in that hot fresh air can be supplied to an entry gate region (18) arranged at the entry of the drying tunnel (14) and/or an outlet gate region (20) arranged at the exit of the drying tunnel (14), from where the hot fresh air can flow into the drying tunnel (14).

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