JPS5842865Y2 - Exhaust heat recovery device in adhesive drying oven - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exhaust heat recovery device that recovers exhaust heat generated in a drying oven during an adhesive drying process and recirculates it as drying hot air.

In general, in order to obtain strong adhesive force with adhesives using solvents, it is necessary to dry the adhesive applied to the adherend with hot air, evaporate the solvent, and then press the adhesive.

Such drying of the adhesive is performed by blowing hot air heated by a burner or the like onto the surface of the material to be dried passing through the drying oven.

In this case, the exhaust heat of the hot air used for drying is recovered, heated, and circulated again as hot air for drying, and the organic solvent that evaporates from the adhesive at that time is oxidized by combustion. It is possible to reduce the amount of fuel used.

For example, in the case of a paint drying oven, Japanese Patent Application Laid-open No. 51-99837 describes a hot air circulation path, burning organic gas generated from the paint in the drying oven with a burner, and removing the remaining exhaust gas. A configuration is disclosed in which post-treatment is performed using a catalyst to make the material non-polluting.

By the way, in this type of paint drying oven, even if the temperature of the drying hot air changes, it does not affect the quality of the product in the slightest, so care should not be taken to control the temperature of the hot air. On the other hand, in an adhesive drying oven, if there is a large temperature change in the hot drying air, it will cause variations in the drying of the adhesive, which will have a large effect on the adhesive strength, so it is necessary to make delicate temperature adjustments. Because of the requirement, hot air cannot simply be circulated.

Therefore, in the past, the hot air used in the drying oven was discharged to the outside together with the evaporated organic solvent.

The present invention has been developed in view of the above points, and it is possible to perform delicate temperature control of drying hot air and significantly reduce fuel consumption when the generated waste heat is circulated. The purpose is to

The configuration of the present invention will be explained below based on the drawings showing one embodiment.

In the figure, 1 is an adhesive drying oven, 2 is a filter, 3 is a blower fan, 4 is a heat exchanger, 5 is a catalyst layer provided in a reaction chamber 6, and 7 is a blower fan.

In the above, the hot air blown onto the adherend 8 that is conveyed through the drying oven 1 by the conveyor is guided to the duct 9 together with the solvent evaporated from the adhesive, and is guided to the filter 2. Blow fan 3. The solvent is sent through a heat exchanger 4 to a reaction chamber 6, where it is decomposed by a catalytic oxidation reaction.

Then, the temperature of the hot air is raised by the decomposition heat generated by the insect removal, and the hot air is sent to the drying oven 1 again through the heat exchanger 49 and the blower fan 7.

Note that 10 is a heating burner provided upstream of the catalyst layer 5;
Reference numeral 12 indicates an exhaust port for excess hot air provided on the way from the catalyst layer 5 to the drying oven 1, and 12 indicates a cooling air suction port that introduces cooling air from the outside.

This suction unit 12 is provided with an air volume damper 13 that adjusts the amount of intake air and an air volume damper 14 that adjusts the amount of hot air sent to the drying oven 1. The temperature of the hot air sent to the drying oven 1 is controlled thereby.

Furthermore, temperature detectors 16 and 17 are installed at the upstream and downstream parts of the catalyst layer 5 in the reaction chamber 6 to control on/off of the burner 10.
is provided, and at the time of start-up, the upstream temperature sensor 16
Therefore, in a steady state, control is performed by the downstream temperature detector 17.

This is because the temperature needs to be higher than a predetermined temperature in order to fully utilize the oxidizing ability of the catalyst, so at the time of startup, the temperature detector 16 on the upstream side controls the burner 10 on and off. This is to promote the catalytic oxidation reaction by maintaining the temperature of the evaporated solvent passing through it at a predetermined temperature, and to quickly shift the temperature of the hot air to a steady state after raising the temperature, thereby reducing fuel consumption.

In addition, in a steady state, when the concentration of the evaporated solvent fluctuates, the catalyst layer 5, which is generated due to the concentration fluctuation,
The temperature difference in the downstream hot air due to the thermal reaction delay in
By controlling the burner 10 on and off by detecting it with the temperature detector 17 on the downstream side, it is possible to reduce fluctuations in the temperature of the hot air and prevent wasteful combustion of the burner 10 to reduce fuel consumption. be.

Therefore, in this way, the temperature detector is switched between the temperature detector at the time of starting and the temperature detector in the steady state.

In the above configuration, the operation will be explained based on a specific example in which toluene is decomposed by a Pt catalyst.
First, at the time of startup, the temperature detector in the upstream section is activated, and the burner 10 is combusted and heated to 180° C., and after about 30 minutes, it is brought to a steady state.

Next, the toluene in the heated gas is decomposed into carbon dioxide gas and water by an oxidation catalyst reaction in the catalyst layer 5, and the temperature is raised to about 300°C by the decomposition heat at that time, and the temperature is raised to about 300°C in the heat exchanger 4. The temperature is lowered to approximately 200° C., and the temperature is further controlled in the external air suction section 12 before being sent to the drying oven 1.

The toluene evaporated in the drying oven 1 reaches a concentration of 500 ppm to 1500 I)pm, is heated by 100°C in the heat exchanger 4, reaches the reaction chamber at a temperature of 180°C, and is converted into carbonic acid in the same manner as above. decomposed into gas and water,
The hot air is sent to the drying oven, but if the temperature downstream of the catalyst layer 5 is low, the burner 1 is
0 is activated to heat the gas in the reaction chamber 4.

In this way, in the present invention, the control of the burner 10 in a steady state is performed by the temperature sensor 17 located downstream of the catalyst layer 5 rather than the upstream region of the catalyst layer 5, so that even if the concentration of the evaporated solvent fluctuates, The thermal response delay caused by the catalyst layer 5 can be significantly reduced, and the temperature change of the hot air can be reduced from ±30°C to ±10°C.

Furthermore, an external air suction section 12 is provided on the way from the catalyst layer 5 to the drying oven 1, and the amount of external air sucked into the suction section is adjusted by a temperature sensor 15 in the drying oven 1. This made it possible to further reduce the temperature change to ±5°C.

Note that 18 indicates an emergency discharge valve, and 19 similarly indicates an emergency stop valve.

As described above, in the present invention, the burner is controlled by a temperature sensor upstream of the catalyst layer during startup, and by a temperature sensor downstream of the catalyst bed in steady state, and external air is controlled on the way to the drying oven. Since the suction section is controlled by a temperature sensor in the drying oven, temperature changes in the hot air caused by delayed thermal reactions in the catalyst layer caused by fluctuations in the concentration of the evaporated solvent can be avoided.
The temperature can be kept to a minimum of 5°C, and therefore, there is no variation in the drying state of the adhesive, and a uniform and strong adhesive force can be obtained, contributing to improved quality.

This is particularly effective when the concentration of the evaporated solvent is significant, such as when the objects to be dried have different sizes.

Furthermore, in addition to circulating the exhaust heat in this way, the combustion of the auxiliary burner is controlled by the temperature sensor downstream of the catalyst layer in a steady state, so the conventional method is 86.
Fuel consumption has been significantly reduced, as kerosene of 51/H has been reduced to 16.81/H.

[Brief explanation of the drawing]

The drawing is a schematic overall view showing an embodiment of the present invention. 1...Drying oven, 5...Catalyst layer, 10.
... Heating burner, 12 ... External air suction section, 15, 16.17 ... Temperature detector.

Claims (1)

[Scope of utility model registration request] In the adhesive drying oven, which supplies hot air into the drying oven to dry the adhesive on the surface of the material to be dried, the waste heat containing the evaporated solvent is guided to the catalyst layer and decomposed, and the temperature is raised by the decomposition heat. A circulation path is used to guide the hot air downstream of the catalyst layer back to the drying oven, and temperature sensors are provided at the upstream and downstream sections of the catalyst layer. In this state, the heating burner upstream of the catalyst layer is controlled by a downstream temperature sensor, and a
An adhesive characterized by having a suction section for introducing air from the outside, and controlling the temperature of the hot air by adjusting the amount of external air sucked into the suction section by a temperature sensor installed in the drying oven. Exhaust heat recovery device in drying oven.