JPH08178202A - Electric heating device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a small and highly reliable electric heating device that can shorten the length of a water pipe and has improved corrosion resistance. In an electric heating device for supplying electric current to a water pipe made of a conductive material to resistance-heat a fluid flowing therein, the water pipe has a resistivity of 100 μΩ · cm at room temperature.
The water pipe is made by using the above-mentioned materials, and a Ni-Cr-Fe-based alloy or a Ni-Mo-based alloy can be used as a material for forming the water pipe.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric heating device,
In particular, it relates to an electric heating device such as an electric boiler that heats an internal fluid by directly energizing a pipe.

[0002]

2. Description of the Related Art Electric boilers are described, for example, in "Boiler Technology Course", Volume 1, pp. 131-132 (April 5, 1972).
Japan, Japan Boiler Association, published by Kyoritsu Shuppan Co., Ltd.). According to the boiler technical course, there are an electrode type in which water is used as an electric resistor to pass a current between electrodes and a hot wire type in which a metal electric resistor is used, but the former is generally used. The boiler main body is small, there is little danger of explosion due to overheating and other causes, it can be used with water containing a relatively large amount of impurities, and it is not difficult to start it in a very short time and maintain efficiency of 95% or more. Many have a working voltage of 3300 V and a capacity of about 500 kW, and a special voltage of 11,000 to 22,000 V and a capacity of 1,000 to
It is described that there are some 2,000 kW.

However, this type of boiler has the following problems. That is, overheating is usually very uneven and concentrated around the heater, which may cause boiling at specific locations and deposit pillows on the heater. The electric boiler also needs to comply with the standard regarding the pressure vessel, and when the pressure of the electric boiler is high, its structure is heavy, and it becomes unfashionable and difficult to move. Furthermore, the problem arises of passing the electrical leads required for the electric heater through the wall of the pressure vessel. In order to solve such a problem, in an electric boiler, particularly an electric steam boiler, a device has been proposed which resistance-heats a meandering pipe and simultaneously heats a medium flowing through the meandering pipe from an inflow pipe to an outflow pipe. (Japanese Patent Publication No. 59-16162). By the way, even in the above apparatus, the meandering tube is made of stainless steel, and it is difficult to reduce the size of the apparatus, and more excellent corrosion resistance is desired.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a small-sized and highly reliable electric heating device which can shorten the length of a water pipe and has improved corrosion resistance.

[0005]

In order to solve the above-mentioned problems, according to the present invention, an electric heating device for supplying an electric current to a water pipe made of a conductive material to resistance-heat a fluid flowing therein is provided. Has a resistivity of 100 μΩ at room temperature
It is intended to be made by using a material of cm or more. As a material for forming the water pipe used in the present invention, Ni-C is used.
An r-Fe based alloy, a Ni-Mo based alloy, etc. can be preferably used.

[0006]

[Function] Fig. 3 is a graph showing the temperature dependence of the resistivity of various materials.
Shown in The material shown in FIG. 3 is an example, but Ni-Cr-
Fe-based alloys (a, c in the figure) and Ni-Mo-based alloys (b in the figure) are materials having a high resistivity of 100 μΩ · cm or more at room temperature and corrosion resistance. In FIG. 3, (a) is JIS NCF.
625, which is equivalent to Inconel Alloy 625, (b)
Corresponds to Hastelloy C according to ASTM UNSN06022, and (c) corresponds to Incoloy Alloy 825 according to JIS NCF825. In FIG. 3, (d) is an austenitic stainless steel (15Cr-10Ni-6M).
n-1Mo), (e) is austenitic stainless steel (18Cr-8Ni), and such commonly used stainless steel has a low resistivity and is difficult to be downsized. ), (B), and (c), it is possible to reduce the size by using a high resistivity material.

Further, when a meandering pipe type water pipe is adopted, if the bending workability of the material is inferior, the bending radius has to be large, and the entire water pipe becomes large in the end, so that it is necessary to reduce the size. Hard to contribute. Therefore, although the material to be used is considerably limited, it can be said that the above-mentioned (a) Inconel alloy 625 and the like are considerably suitable materials. The resistance as a tube can be expressed by the following formula. R = ρ × L / A (R: resistance (Ω), ρ: resistivity (Ω · cm), L: pipe length (m), A: pipe cross-sectional area (cm ² )) That is, even if a high resistance material is used However, using a thick material has no characteristic. The effect of selecting a high resistance material is
It can be exhibited when the wall thickness is almost the same, and if the material with poor bending workability is used, the bending radius becomes large. Even if the tube length can be shortened by using a material with high resistance, the total height of the water pipe part will be high and downsizing will be achieved. Will be difficult to contribute to.

[0008]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. Example 1 FIG. 1 shows a process flow diagram of electric boiler equipment using the electric heating apparatus of the present invention. FIG. 2 shows a perspective view of the electric boiler body. In FIGS. 1 and 2, reference numeral 1 denotes a water pipe, which is a multiple of 3 when three-phase alternating current is applied, but in the drawings, 3 pipes are shown for convenience. Further, 2 is a pipe head, 3 is a steam drum, 4 is a three-phase power source, 5 is a transformer and a power regulator, 6 is a circulation pump, and 7 is a circulation pipe.

Numeral 8 is a deaerator, and the water 16 to be supplied is deionized by the demineralizer 11 and introduced into the deionized water tank 12 to obtain the water supply pump 13 and deaerated by the deaerator 8. It is supplied as pure water to the steam boiler 3. The makeup water passes through the circulation pipe 7 and is introduced into the header 2 by the circulation pump 6.
Water pipe 1 which is heated by the power supply from pipe heads 2 to 4
Enters, is heated and is introduced into the steam drum 3. The steam generated in the steam drum 3 is supplied from the steam pipe 15 to the destination through the silencer 10. Also steam boiler 3
A safety valve 9 is provided in the. Water that does not evaporate is circulated in the water pipe 1 by a circulation pump to take a circulation path for heating. Further, 14 is a cooler and 17 is cooling water. Also, FIG.
In the figure, 18 is a boiler enclosure, 19 is a maintenance window, and 20 is an inspection door. By using such a device, the material of the pipe of the water pipe portion 1 is known SUS316T.
When using B and JIS NCF625TB (inconel alloy 625 equivalent product) of the present invention, the required pipe length is SUS3.
Table 1 shows a comparison result using the material of the present invention when 16 TB is 1.

[0010]

[Table 1] Note) See Fig. 3 for resistivity at 200 ℃. It is assumed that SUS316TB conforms to (d) of FIG. From this, the material can be changed from SUS316TB to NCF625T.
When it was changed to B, the pipe length was reduced by about 1/3, which helped to downsize the water pipe portion and improve the corrosion resistance.

[0011]

The following effects are brought about by using the alloy steel having a large resistivity and corrosion resistance for the water pipe (heating part) of the electric boiler. Since the calorific value per unit length of the water pipe increases, the pipe length was shortened, which contributed to downsizing. Since the corrosion resistance of the water pipe is improved, the reliability is improved.

[Brief description of drawings]

FIG. 1 is a process flow diagram of an electric boiler facility using an electric heating device of the present invention.

FIG. 2 is a perspective view of the electric boiler body of FIG.

FIG. 3 is a graph showing temperature dependence of resistivity.

[Explanation of symbols]

1: Water pipe (heating unit), 2: Heading, 3: Steam drum,
4: 3-phase power supply, 5: transformer, power regulator, 6: circulation pump, 7: circulation pipe, 8: deaerator, 9: safety valve, 1
0: Silencer, 11: Demineralizer, 12: Pure water tank, 1
3: Water supply pump, 14: Cooler, 15: Steam pipe, 16:
Water, 17: Cooling water, 18: Boiler enclosure,
19: Maintenance window, 20: Inspection door

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takao Sato 11-1 Haneda Asahi-cho, Ota-ku, Tokyo Ebara Corporation (72) Inventor Masaaki Yoneda 11-1 Haneda-asahi-cho, Ota-ku, Tokyo Inside the EBARA CORPORATION

Claims (2)

[Claims] 1. An electric heating apparatus for supplying an electric current to a water pipe made of a conductive material to resistance-heat a fluid flowing therein, wherein the water pipe has a resistivity at room temperature of 100 μΩ · c.
An electric heating device characterized by being made using a material of m or more. 2. The material for forming the water pipe is Ni-Cr-F.
The electric heating device according to claim 1, wherein the electric heating device is an e-based alloy or a Ni-Mo based alloy.