JPH0632989U - Vacuum dryer - Google Patents

Abstract

(57) [Summary] [Purpose] For the purpose of protecting the global environment, the use of CFCs for cleaning is regulated, and water-based ultrasonic cleaning is adopted as an alternative technology. As a drying method after this washing, a rapid vacuum dryer with no residue is provided. [Construction] In a vacuum dryer in which the dried product in a closed vacuum tank is heated by a plurality of far-infrared plate heaters and the vacuum tank is evacuated by a vacuum pump, an electric resistor is buried in an electrically insulating resin. It is a vacuum dryer that uses a far-infrared plate heater and a vacuum pump that can control the pressure higher than the triple point of evaporation material. [Effect] This is a vacuum dryer in which electric resistance is buried in an electrically insulating resin to prevent electric leakage. In addition, it is a vacuum dryer that emits far infrared rays with high efficiency, supplies heat of vaporization, and uses a vacuum pump that does not reach the pressure for freezing, so that the drying time is short.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The use of CFCs for cleaning, which is one of the ozone depleting substances, is being regulated for the purpose of protecting the global environment. As an alternative to CFC cleaning, water-based ultrasonic cleaning using a water-based cleaning agent or pure water is adopted. We found that water-based ultrasonic cleaning requires a drying step, and that hot air drying leaves a watermark, which results in a long drying time. The present invention relates to a vacuum dryer used in a drying process after water-based ultrasonic cleaning.

[0002]

[Prior art]

 The present inventor has applied for an infrared heating type vacuum dryer equipped with a far infrared plate heater and a water jet pump as a vacuum dryer that does not freeze during drying (Japanese Patent Application No. 1-28419). This infrared heating type vacuum dryer is composed of a water jet pump in which two or more flat infrared plate heaters are arranged in a shelf in a vacuum chamber and the inside of the vacuum chamber is exhausted.

The flat plate-shaped infrared plate heater is arranged so as to completely replenish the latent heat of vaporization lost by the drying in order to prevent the material to be dried in the vacuum chamber from freezing and lowering the drying speed. As shown in FIG. 2, the flat plate-shaped infrared plate heater has a foil-shaped heating resistor 1 sandwiched by two sheets of electrical insulating material 2 mica, and further sandwiched by two sheets of infrared radiation substance 3. It was structured. The water jet pump was a pump capable of discharging a large amount of water without freezing the material to be dried, and also had a function of condensing water vapor.

[0004]

[Problems to be solved by the device]

 However, when the electrode with the silver plating on the surface was ultrasonically cleaned with pure water and then dried using the infrared heating vacuum dryer, the insulating mica of the far infrared plate heater absorbed moisture, resulting in deterioration of the electrical insulation performance. , There was a short circuit. Although the water jet pump does not reduce the pressure below the triple point of water, it takes time to reach a predetermined pressure, so the entire drying time is extended, and the cooling heat of steam and the ejector section There was a drawback that the total frictional heat had to be cooled.

[0005]

[Means for Solving the Problems]

 In order to solve the above problems, the present invention provides an electrically insulating performance in a vacuum dryer in which an object to be dried in a closed vacuum tank is heated by a plurality of far-infrared plate heaters and the inside of the vacuum tank is exhausted by a vacuum pump. The present invention provides a vacuum dryer characterized by using a far-infrared plate heater in which an electric resistor is embedded only in a resin containing a resin and a vacuum pump capable of controlling a pressure higher than the triple point of evaporation material. .

[0006]

[Action]

 The present inventor has found that as a method of preventing electric leakage due to moisture absorption, burying the electric resistor 1 only in a resin having excellent electric insulation is a means for electrically insulating and effectively supplying heat of vaporization. I figured it out.

Electrical insulation must prevent vacuum discharge and leakage. Vacuum discharge can be prevented by burying the electric resistor 1 as shown in FIG. Leakage can be prevented by using fluororesin 4, silicon resin 5, polyimide 6 and the like, which have excellent insulation and heat resistance. It should be noted that other resins having equivalent performance will not cause any problems. Table 1 shows the insulation and heat resistance. In a vacuum, the heat of vaporization is supplied from the far infrared plate heater as radiant heat, so that a far infrared emissivity of 80% or more is required as shown in FIG.

[0008]

[Table 1]

Next, the vacuum pump has a high evacuation speed in order to shorten the start-up time, and is a vacuum pump that can control the pressure higher than the triple point of the evaporation material in order not to freeze the dry material. Limited. Therefore, in the case of drying water, a dry vacuum pump, which has an ultimate pressure higher than 4.6 Torr and whose performance is not deteriorated by water vapor, and which does not use a seal liquid in the rotating part, is suitable. It should be noted that a vacuum pump with equivalent performance will not cause any problems.

When drying the organic solvent or the like, an oil rotary vacuum pump can be applied. A condenser that condenses the expanded gas into a liquid may be installed to assist the vacuum pump. The condenser is preferably a liquid condenser for easy handling of the recovered material.

[0011]

【Example】

 Hereinafter, the present invention will be described with reference to the embodiments of FIGS. FIG. 4 is a structural conceptual diagram of the vacuum dryer. The specifications of this vacuum dryer were as follows. The vacuum pump 7 is a dry type with a motor output of 1.5 kW, an exhaust speed of 670 liters / min (at 20 Torr), and an ultimate pressure of 10 Torr. The vacuum chamber 8 had a capacity of 150 liters, and five far infrared plate heaters 9 were arranged at 80 mm intervals. A tray 11 on which the dried product 10 was placed was placed between the far infrared plate heaters 9. The size of the tray 11 was 440 mm width × 710 mm length, and the bottom surface was lath-shaped.

The far-infrared plate heater 9 had a structure in which the heating resistor 1 made of a stainless steel foil of 50 μm, which was linearly processed to have a resistance of 100 Ω, was embedded in a fluororesin 4 having a thickness of 2 mm. The size is 470 mm width × 720 mm length × 2 mm thickness, and the structure is shown in FIG. The emissivity curve of the fluororesin 4 was as shown in FIG. The surface temperature of the far infrared plate heater was automatically controlled to 130 ° C.

The condenser 12 was a cooler having a cooler output of 0.75 kW and a cooling capacity of 1000 kcal / h (at a liquid temperature of 5 ° C.), and chilled water cooled to 5 ° C. was circulated at 50 liters / min.

The inventor of the present invention dried the ultrasonically-cleaned convex silver-plated electrode using this vacuum dryer. The electrode of the dried sample was spread by 4 kg for each tray and arranged in each stage. The dimensions of the electrodes were 7 mm width x 10 mm height x 0.1 mm thickness. The amount of water attached to the electrode was 100 g / tray. After a drying time of 13 minutes, the water was completely dried. FIG. 5 shows the pressure 13, the electrode temperature 14, the heater temperature 15 and the cooling water temperature 16 for each elapsed time. Even if this drying was repeated for 8 hours a day and 90 days continuously, the insulation of the far infrared plate heater did not deteriorate. Table 2 shows the insulation resistance value when a direct current of 500 V was applied for 1 minute.

The drying time of the same sample by the conventional infrared heating type vacuum dryer was 20 minutes. FIG. 6 shows the pressure 17, the electrode temperature 18, the heater temperature 19 and the cooling water temperature 20 for each elapsed time. The specifications were a water jet pump output of 1.5 kW, a refrigerator output of 1.5 kW, and a cooling capacity of 2000 kcal / h (at a liquid temperature of 5 ° C). The insulation resistance value of the heater after continuous use for 90 days was remarkably lowered as shown in Table 2.

[0016]

[Table 2]

[0017]

[Effect of device]

 As described above, according to the present invention, by using the far infrared plate heater in which the electric resistor is embedded only in the resin having the electric insulation performance, and the vacuum pump capable of controlling the pressure higher than the triple point of the evaporation material, It provides a vacuum dryer that does not leak and has a fast drying time.

[Brief description of drawings]

1 is a sectional view of a far infrared plate heater of the present invention, FIG. 2 is a sectional view of a conventional far infrared plate heater, FIG. 3 is a far infrared emissivity curve diagram, FIG. 4 is a conceptual diagram of the structure of the present invention, and FIG. FIG. 6 is a temperature / pressure diagram for each elapsed time of the present invention, and FIG. 6 is a temperature / pressure diagram for each elapsed time of the conventional infrared heating vacuum dryer.

[Explanation of symbols]

1: Heating resistor, 2: Mica electrical insulating material, 3: Far infrared radiation material, 4: Fluorine resin, 5: Silicon resin, 6: Polyimide, 7: Dry type vacuum pump,
8: Vacuum tank, 9: Far infrared plate heater, 1
0: dried product, 11: tray, 12: condenser, 13:
Pressure (drying example of the present invention), 14: temperature of sample electrode (drying example of the present invention), 15: heater temperature (drying example of the present invention), 16: cooling water temperature (drying example of the present invention), 17:
Pressure (conventional drying example), 18: sample electrode temperature (conventional drying example), 19: heater temperature (conventional drying example),
20: Cooling water temperature (conventional drying example).

Claims (1)

[Scope of utility model registration request] 1. A vacuum dryer in which an object to be dried in a closed vacuum tank is heated by a plurality of far-infrared plate heaters, and the inside of the vacuum tank is evacuated by a vacuum pump. A vacuum dryer characterized by using a far-infrared plate heater in which is embedded and a vacuum pump capable of controlling the pressure higher than the triple point of evaporation material.