JPS582579A - Method and device for recovering heat in painting oven - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for recovering heat in a painting oven and an apparatus for the same, and in particular to miniaturization of the apparatus by improving the oven atmosphere circulation mechanism provided in each heating zone in the painting oven. The present invention also relates to a thermal recovery method and apparatus designed to save energy.

Conventionally, in the painting process where a strip coated with a specified paint such as a thin steel plate is run and continuously heated, dried, and baked, it is important to take precautions against the accumulation of organic solvents that are caused by the strip. is needed.

For this purpose, for example, as shown in FIG. 1, in a coating open 2 consisting of a drying zone 4 in which a strip 1 coated with a predetermined paint is run, and a subsequent baking zone 6, a solvent-containing furnace is used. By discharging the gas using the suction fan 8, the concentration of evaporated solvent in the atmosphere within the oven 2 is reduced, thereby preventing an explosion. More specifically, drying zone 4
The in-furnace gas containing the solvent is taken out by the suction fan 8 from near the inlet of the incinerator (catalytic combustion type deodorizing device) equipped with a known noble metal catalyst such as platinum or palladium.
10 to be burned and deodorized. A part of this combustion exhaust gas is released into the atmosphere as needed, and the remaining combustion exhaust gas is used for heating the strip l.
branched into one circulation mechanism 13 via a valve 11.
The pulp is then guided to two other circulation mechanisms 14 via the pulp 12. These circulation mechanisms 18.14 heat the furnace gases led from the drying zone 4 and the baking zone 6, respectively, by appropriate heating means such as heat exchangers 16.18, and then heat them together with the combustion exhaust gas. , hot air circulation fan 20.
22 to circulate the gas into each zone and heat the strip 1 in each zone, thus achieving the purpose of utilizing heat in the combustion exhaust gas and diluting the gas in the furnace. Heating takes place.

In such equipment, even though the amount of evaporated solvent generated differs from zone to zone, the gas in the furnace is sucked and exhausted all at once, so that the solvent in the atmosphere inside the coating opening is reduced. This has the advantage of stabilizing the content, but on the other hand, it requires 7 amps of suction to process the gas in the furnace all at once.
It is inevitable that the ability and Incinerator 10 will become larger, and it is a must for each lane! In order to circulate and supply the required amount of heat, an automatic heat-resistant valve that can withstand high heat of approximately 700°C is used to distribute the combustion exhaust gas generated by the incinerator lO to each circulation mechanism. There are problems in that it is necessary to use pulps 11 and 12 or to install separate open heaters or cooling devices that can be finely adjusted and controlled in each circulation mechanism.

In view of such circumstances, the present invention provides for the purpose of the present invention, in which a material coated with a predetermined paint is heated in an oven to dry and bake the material, and the exhaust gas containing the solvent is discharged from the oven. After the gas is guided to an incinerator and the solvent in the exhaust gas is combusted under the action of a catalyst, at least a part of the combustion exhaust gas is circulated through the ovens 2'' of each of the plurality of heating zones in the oven. Part number 0 is supplied, while a part of the open internal surrounding air circulated in each of these circulation paths is respectively combusted under the action of a catalyst and returned to the oven.

In addition, in the present invention, in order to effectively carry out the above method, a material coated with a predetermined paint is heated inside the opening to dry and bake it. , the exhaust gas containing the solvent discharged from the oven is led to an incinerator, and after the solvent in the exhaust gas is combusted under the action of a catalyst, at least -g of the combustion exhaust gas is transferred to multiple sources in the oven. In the heat recovery device used for heating the Mij material ladle in the heating zone, (1) each circulation path that circulates the atmosphere inside the oven in each heating zone in the oven, and (
2) a catalytic combustion mechanism provided in each of the circulation paths and provided with a catalyst layer for combusting the solvent in the atmosphere inside the open; -(3) combustion exhaust gas from the incinerator in the catalytic combustion mechanism; (4) atmosphere introducing means for introducing a part of the atmosphere inside the open that is circulated through the circulation path into the catalytic combustion mechanism; That's how many digits there are.

Thus, according to the present invention, in addition to the solvent treatment in the iscinerator that burns the solvent under the action of the catalyst, the solvent treatment in each zone is possible by using the circulation path that allows low-temperature combustion by the catalytic combustion mechanism. Differences in the rate of generation of evaporated solvent within the coating oven can be effectively averaged out, and an energy saving effect can be enjoyed due to the heat generated within the oven. Furthermore, since solvent treatment is carried out in each zone, the incinerator for batch treatment becomes small-scale, and the calorific value of the flue gas is also reduced. It also becomes easier. Another advantage is that the capacity of the suction fan for circulation can be small.

Hereinafter, two embodiments of the present invention will be described in more detail based on the drawings.

First, in FIG. 2, 3o is a coating oven that heats a strip 32 such as a thin steel plate coated with a predetermined paint while running it, and performs predetermined drying and baking. consists of two zones, zone 36. And painting oven 8
The solvent-containing furnace gas (exhaust gas) sucked in by the suction fan 40 through the conduit passage 38 from the vicinity of the 32-person strip 0 is transferred to the branch passage 421. ．． If it is led to the incinerator 46 via the valve 44, on the other hand, the branch path 48
, the predetermined amount can be discharged to the outside of the system as a bypass via the evaporation tube 50 if necessary.

The branch pipe 48 and the valve 50 are connected to the external discharge mechanism 5.
1 is formed. Incidentally, the above-mentioned Incinere aid p%--1
-55 k'-6F? , Soldier,, Mae, □I! The furnace gas that could not be guided to 84□ is heated in the heat exchange section 52 and then guided to the catalytic combustion section 54 through the conduction path 56.

In this catalytic combustion mechanism 4, the gas in the furnace is combusted and deodorized under the action of a catalyst such as platinum or rhodium, if necessary with the help of a burner 55, and then transferred to the catalytic combustion section 54 in heat exchange s52. After being used to preheat the introduced gas in the furnace, a part of the gas is discharged from the exhaust pipe 60 to the outside of the system via the pallet 9-58, if necessary. The remaining combustion exhaust gas passes through the conduit 62 and is divided into two parts, and a part of it passes through the valve 62.
4 to the first open heater 6 by the conduction path 66 via M.
8, and the rest is led to a second open heater 74 via four passages 72 via a pulp 70. Here are the enemy passages 62, 66, 72 and the pulp 6.
4.70 forms the combustion exhaust gas introduction means 75.

Then, one of the two divided combustion exhaust gases is guided to the first oven heater 68 through a conduit passage 66 under the flow rate regulation by the pulp 64, and a part of the combustion exhaust gas is guided to the first oven heater 68 as it is through hot air circulation.
0, and the rest is guided to a catalytic combustion chamber (catalytic combustion mechanism) 78.

On the other hand, the furnace gas containing the evaporated solvent in the first drying zone 84 flows through the catalytic combustion chamber 84 through the conduit passage 84 provided with the valve 83.
The air is guided into the oven heater 68 by a conduction path 86 provided with a pulp 85, and then directly into the hot air circulation fan 80.

In this way, the gas introduced into the catalytic combustion chamber 78 is combusted at a low temperature under the action of the catalyst, and the combustion exhaust gas is transferred to the catalyst layer 79 in the first oven heater 68.
The conduction path 86 is regulated by the valve 85 and does not pass through.
The hot air circulation fan 80 sucks in the furnace gas, ie, the gas from the drying zone, and returns it through the conduit passage 82 into the drying zone 34, where the strip 32 is heated and dried.

Similarly, the other of the two divided combustion exhaust gases is led to the second oven heater 74 through the conduit 72, a part of which is directly directed to the hot air circulation fan 90, and the rest of which is directed to the catalytic combustion chamber.
(Catalytic combustion mechanism) 88.

On the other hand, during baking, the furnace gas in the zone 36 is not guided into the catalytic combustion chamber 88 through the conduit passage 94 provided with the valve 93, but is further guided directly into the second oven heater 74 through the conduit passage 96 provided with the valve 95. The hot air is guided to a hot air circulation fan 90.

The combustion exhaust gas generated by the combustion action in the catalyst layer 89 in the catalytic combustion chamber 88 does not pass through the catalyst layer 89, but the furnace gas is guided through the conduit passage 96 under the flow rate regulation by the valve 95. It is sucked together with the hot air circulation fan 90 and returned to the zone 86 through the conduction pipe 92, and the heating and firing of the IJ tube 32 is performed.

Here, a first open heater 68 and a hot air circulation fan 80 are installed.
．． The conduit 82.84.86 and the valve 88.85 form the first circulation path 99 for the drying zone 84, and likewise the second oven heater 74, the hot air circulation 7 amp 90 conduit 92.94.96 and Valves 98 , 95 form a second circulation path 100 to zone 86 .

Therefore, in such a heat recovery device, the temperature at 50°C
Because solvent treatment is possible with low-temperature combustion using a catalytic combustion method, the concentration of solvent in the furnace can be partially reduced, and the second circulation 1h + 100 is evaporation in zone 36. It is possible to circulate the in-furnace gas with a low solvent concentration and perform solvent treatment using a low-temperature combustion mechanism also using the catalytic combustion method at a circulation rate different from that in the first circulation path 99. In other words, the amount and temperature of hot air required in each heating zone are effectively assisted by the combustion of the furnace gas in each circulation path. In this way, differences in the rate of evaporated solvent generation within the wrapping oven 30 can be effectively averaged out, thereby eliminating the risk of explosion within the furnace.

It is.

In addition, the hot air heat 11. required in each heating zone 84.86. (temperature) can be effectively controlled by the supply heat rate of the flue gas from the incinerator 46 and the combustion heat generated and caused in the catalytic combustion chamber 78.88 in the oven heater 68.74. (Valve 88.
93), the control became extremely easy and the solvent combustion energy could be used effectively.

Furthermore, as a result of the solvent treatment being carried out to a certain degree in each zone, the concentration of solvent in the atmosphere inside the coating oven 80 decreases, and the amount of exhaust from the oven 30 decreases, so that the incinerator 46 for batch treatment is reduced. In addition, the capacity of the suction fan 40 is not small and has an excellent effect such as 6, which further improves the energy saving effect.

In addition, regarding the out-of-system discharge mechanism 51 as a bypass, generally speaking, solvent-containing paint differs depending on the type of coating, coating thickness, material board width, and line speed, and the amount of heat required to raise the temperature of the material also depends on the set temperature. Since it varies depending on the spraying temperature, the amount of solvent, the size of the material, etc., the amount of heat possessed by the evaporated solvent generated in the oven 20 often exceeds the amount of heat required to raise the temperature. In this case, installing a furnace that burns the entire amount of suction gas would increase the scale of the furnace, resulting in auxiliary combustion,
Since the fuel for the gas 55 is also uneconomical, the suction gas unnecessary for raising the temperature of the material is directly discharged into the atmosphere by the discharge mechanism 51 without passing through the combustion furnace.

Further, in the above description, the coating oven 30 is formed of two zones, the drying zone 34 and the baking zone 36, but the present invention is not limited to this in any way, and there are multiple zones. It suffices if there are 1 heating zone. Furthermore, although the exhaust mechanism 51 is provided as a bypass, it is not necessary if the amount of heat the evaporated solvent has is not excessive. - Moreover, it goes without saying that various modifications and improvements can be made in addition to this J based on the knowledge of those skilled in the art without departing from the spirit of the present invention.

[Brief Description of the Drawings] Fig. 1 is a cross-sectional explanatory diagram schematically showing a heat recovery device of a conventional painting oven, and Fig. 2 is a cross-sectional explanatory diagram showing a heat recovery device of a conventional painting oven. FIG. , 30: Painting oven 34: Drying zone 36-: Baking zone 46: Incinerator 75; Combustion exhaust gas introduction means 99. 100: Circulation path 84. 94: Conduit path Applicant Daido Steel Co., Ltd.

Claims (1)

[Scope of Claims] (]) In a painting oven in which a material coated with a predetermined paint is heated in an opening to dry and bake the material, exhaust gas containing a solvent is discharged from the opening. is introduced into an incinerator, and after the solvent in the exhaust gas is combusted under the action of a catalyst, at least a portion of the combustion exhaust gas is supplied to an open internal atmosphere circulation path of each of the plurality of heating zones in the oven. A method for recovering heat in a coating oven, characterized in that a part of the atmosphere inside the oven circulated in each of the circulation paths is combusted under the action of a catalyst, and then returned to the opening. (2) In the painting oven, which is designed to dry and bake the material coated with the specified paint by heating it in the oven, the exhaust gas containing the solvent discharged from the opening is guided to the incinerator, and the exhaust gas is A heat recovery device that burns a solvent in a gas under the action of a catalyst and then uses at least a portion of the combustion exhaust gas to heat the material in a plurality of heating zones in the oven, each heating zone in the oven. a catalytic combustion mechanism comprising: each circulation path for circulating the oven atmosphere in each zone; and a catalyst layer provided in each circulation path for burning a solvent in the oven atmosphere; a combustion exhaust gas introducing means for introducing combustion exhaust gas from the incinerator into the combustion mechanism and heating the catalyst layer to a temperature sufficient to cause the solvent to burn; and an oven atmosphere that is circulated through the circulation path within the catalytic combustion mechanism. (3) A heat recovery device for a coating oven, characterized in that it includes an atmosphere introducing means for guiding a portion of the coating oven. 3. The device according to claim 2, further comprising a discharge mechanism for extracting a predetermined amount of the exhaust gas from the outer ring of the system.