JPS6365251A - Heating of liquid - Google Patents

Abstract

PURPOSE:To permit a time for heating liquid to an objective temperature to be shortened remarkably, by a method wherein the liquid in a tube member with an opening, which is made of fluorine resin and is dipped into a pipe or a tank made of fluorine resin, is heated directly by the projection of microwave. CONSTITUTION:Liquid, objective for heating, is made to flow through a tube 5, made of fluorine resin, with a constant flow rate and microwave is projected from the microwave transmitting unit 3 of a microwave generating unit 1 against the liquid flowing through the tube 5 of fluorine resin simultaneously with the flow of the same liquid. The liquid in the tube 5 of fluorine resin may be deemed as a dielectric load with respect to the projection of the micro wave, therefore, the liquid may be heated directly while flowing through the tube 5 of fluorine resin by the conversion of the microwave into heat energy due to an electric power loss. In this case, a shield case 40 prevents the leakage of the microwave to the outside of the system.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a liquid heating method for heating corrosive liquids such as chemical liquids, high purity reagents, and other corrosive liquids such as acids and alkalis used in semiconductor manufacturing processes.

(Prior Art) Conventionally, the following methods are known as methods for heating liquids such as chemicals used in semiconductor manufacturing processes.

(a) A method of heating using a so-called throw heater in which a plate-shaped electric heater is completely coated with fluororesin.

(b) A method in which a nichrome wire is passed through a fluororesin tube and coated, and the coated tube containing the nichrome wire is heated by an injection heater formed into a coil shape.

(C) A method in which a rod-shaped heater is heated using an immersion heater completely covered with fluororesin.

(d) A method in which a heated fluid is passed through a bundle of fluororesin tubes, and the tube bundle is immersed in a chemical solution to heat it by heat exchange.

(Problems to be solved by the invention) However, in such conventional heating methods,
The thermal conductivity of the fluororesin coating is low due to the properties of the coating, and the heat resistance temperature of the fluororesin is lower than the heating capacity of the heater, so it is not possible to raise the temperature of the heater, and the temperature of the chemical solution used in the semiconductor manufacturing process is low. There was a problem in that it took a very long time, for example, one day and night, to heat the water to a predetermined target temperature.

(Means for Solving the Problems) The present invention has been made in view of these conventional problems, and is capable of efficiently heating liquids such as corrosive chemical solutions or high-purity reagents to a predetermined temperature in a short time. It is an object of the present invention to provide a method for heating a liquid.

In order to achieve this objective, in the present invention, a liquid such as a corrosive chemical solution or a high-purity reagent to be heated is passed through a fluororesin tube, and as the liquid flows through the tube, a microwave emission source is emitted. The liquid is heated by irradiating it with microwaves.

Further, in the present invention, a liquid such as a corrosive chemical liquid or a high-purity reagent is stored in a tank, and a fluororesin open tube member that receives liquid circulation due to natural convection is immersed in the tank. The liquid in the open lobe member is heated by being irradiated with microwaves from a microwave emission source installed outside the tank through a waveguide lined with a fluororesin and an electronic shield.

(Function) According to the heating method of the present invention, the internal liquid of the open fluororesin tube member immersed in the fluororesin tube or tank is directly heated by microwave irradiation, so heating efficiency is high. , it is possible to significantly shorten the heating time to heat a certain amount of liquid to a predetermined target temperature, and further,
Fluororesins are less affected by microwave irradiation and can efficiently heat liquids without causing problems with the heat resistance of fluororesins.

(Example) FIG. 1 is an explanatory diagram showing an example of the apparatus configuration used in the heating method of the present invention.

In FIG. 1, reference numeral 1 denotes a microwave generator, which has a microwave transmitter 2 made of a magnetron. In response to the high voltage from the high voltage generation circuit 4 that generates high voltage of several KV or more based on the
For example, microwave transmitter 2 emits microwaves of 2450 MHz. A microwave generator 1 equipped with a microwave transmitter 2 is built into a shield case 4,
A fluororesin tube 5 is located at a position opposite to the microwave transmitter 2 of the microwave generator 1 incorporated in the shield case 4.
A liquid such as a corrosive chemical solution or a high-purity reagent to be heated is pumped into the fluororesin tube 5 as shown by the arrow to flow through it.

-5= Next, to explain the heating method of the present invention using the device configuration shown in FIG. At the same time as the liquid flows through the microwave transmitter 3 of the microwave generator 1
The liquid flowing inside the fluororesin tube 5 is now irradiated with microwaves. Since the liquid inside the resin tube 5 can be regarded as a dielectric load when irradiated with microwaves, the liquid is directly heated as it flows through the fluororesin tube 5 by exchanging heat energy due to microwave power loss caused by the liquid. Become so.

At this time, the seed case 4 comes to prevent the microwave from leaking to the outside.

Further, the temperature of the liquid can be controlled by adjusting the flow rate of the liquid flowing through the fluororesin tube 5, switching the power supply, changing the microwave transmission capacity, etc.
A temperature sensor may be provided on the outflow side of the microwave, and feedback control such as adjusting the flow rate, switching the power source, changing the microwave transmission capacity, etc. may be performed so that the temperature detected by the temperature sensor matches the set temperature.

On the other hand, the fluororesin tube 5 through which liquid flows has a fluororesin that is resistant to corrosive liquids and has sufficient mechanical strength to be used as a structural material and a piping material for flowing liquid. have.

The fluororesin of the fluororesin tube 5 used in the heating method of the present invention is PTFE (tetrafluoroethylene resin>
, PFA (tetrafluoroethylene/perfluoroalkyl vinyl ether copolymer resin), FEP (tetrafluoroethylene/hexafluoropropylene copolymer resin), PCTFE (trifluorochloroethylene resin), PVdF (vinylidene fluoride resin> ,
ETFE (tetrafluoroethylene/ethylene copolymer resin), E
CTFE (trifluorochloroethylene/ethylene copolymer resin)
, EPE (fluorinated ethylene propylene/ether copolymer resin), etc.

Among these, PTFESPFA has particularly excellent heat resistance and
It can be used at high temperatures up to ℃, has excellent chemical resistance, and has sufficient mechanical strength. Furthermore, due to its low dielectric constant, it is hardly affected by microwaves and can transmit the irradiated microwaves to the internal liquid with almost no attenuation, making it the most suitable for the heating method of the present invention. It can be called a material.

FIG. 2 is an explanatory diagram showing another embodiment of the fluororesin tube 5 used in the apparatus configuration of FIG. ＞
As shown in FIG. 2, the fluororesin tubes 5 are formed into a coil shape, and as shown in FIG. Figure 2 (C)
It is desirable to form the fluororesin tube 5 in a meandering shape as shown in FIG.

FIG. 3 is an explanatory diagram showing a device configuration for realizing another heating method of the present invention. It is characterized in that a liquid such as a reagent is heated by microwave irradiation.

In FIG. 3, 7 is a tank that stores the liquid 12 to be heated, and an open tube member 8 made of fluororesin is immersed in the tank 7. For example, as the open tube member 8, both ends are An open cylindrical member is used and is placed in the tank 7 with the cylindrical member standing vertically and opening upward and downward.

On the other hand, a microwave generator 1 equipped with a microwave transmitter 2 is installed outside the tank 7.
A waveguide 9 connects the opening tube member 8 and the opening tube member 8 immersed in the liquid in the tank 7 so that microwaves from the microwave transmitter 2 can be supplied to the inside of the opening tube member 8. Open-9 = As is clear from FIG. 4, which is an enlarged view of part A, the rotube member 8 has a structure in which a fluororesin lining 8b is provided on the inside and outside of a conductive pipe 8a.

In the heating method of the present invention using the device configuration shown in FIG. The liquid inside the open tube member 8 is heated by microwave irradiation. Open tube 8 by microwave irradiation
When the liquid in the tank 7 is heated, the liquid 12 in the tank 7 causes natural convection as shown by the arrow, and the liquid in the tank 7 can be uniformly heated without the need for forced stirring. Of course, the heating temperature can be controlled by switching the power supply, changing the microwave transmission capacity, etc.

(Effects of the Invention) As explained above, according to the present invention, in the method of first heating the liquid by irradiating it with microwaves during the process of flowing the liquid into the fluororesin tube, the liquid is heated by microwaves. The microwaves pass almost completely through the fluororesin tube, allowing efficient heating of only the liquid inside, and therefore a certain amount of liquid can be heated to a predetermined target temperature in a short period of time.

In addition, since the part that comes into contact with the fluid is made of fluororesin,
It can be used for all kinds of corrosive liquids or chemicals, and since the fluororesin is not heated by microwave irradiation, there is no elution of impurities from the fluororesin, and the purity of the liquid can therefore be maintained at a high level. .

On the other hand, in a heating method that heats the liquid stored in a tank by irradiating microwaves, the liquid is heated by irradiating microwaves to generate natural convection without stirring the liquid. The temperature of the liquid inside can be raised uniformly.

Further, regardless of the heating method, since the liquid can be heated to the target temperature in a short period of time, the temperature can be easily controlled by a feedback system using a temperature sensor.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of the configuration of an apparatus used in the heating method of the present invention, FIG. 2 is an explanatory diagram showing the shape of the fluororesin tube used in the apparatus of FIG. 1, and FIG. The figure is an explanatory diagram showing an example of the configuration of an apparatus used in another heating method of the present invention, and FIG. 4 is an enlarged sectional view of section A in FIG. 3. 1: Microwave generator 2 2 Microwave transmitter 3: Power supply circuit 4: High pressure generation circuit 5: Fluororesin tube 6: Joint 7: Tank 8: Open tube member 8a: Conductive pipe 8b: Fluororesin lining 9: Waveguide 10: Shield case

Claims (2)

[Claims] (1) A liquid such as a corrosive chemical solution or a high-purity reagent is passed through a fluororesin tube, and as the liquid flows through the tube, microwaves from a microwave emission source are irradiated to heat the liquid. A liquid heating method characterized by: (2) A liquid such as a corrosive chemical solution or a high-purity reagent is stored in a tank, and a fluororesin coating and electromagnetic shield are applied to the fluororesin open tube member immersed in the tank from a microwave emission source installed outside the tank. A method for heating a liquid, characterized in that the liquid in the open tube member is heated by being irradiated with microwaves through a waveguide provided with the above.