JPH0245600Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a heater wire that is buried vertically underground, which facilitates facility work.

In recent years, in order to prevent freezing of the soil around underground tanks that store low-temperature liquids such as liquefied natural gas, soil Heater wires 3 are placed in the vertical direction of soil 2 to heat the soil.

Conventionally, when burying a heater wire vertically underground, a method has been adopted in which a protection pipe 4 is buried underground in advance and the heater wire is inserted into it.

The length of the protection pipe is usually 30 to 50 m, and the heater wire also needs to be of the same length, but in order to obtain uniform temperature distribution, it is desirable to place the heater wire at the center of the protection pipe.

However, since the protection pipe is buried underground and the heater wire is flexible, when inserting the heater wire from the ground surface to the bottom of the protection pipe,
Visual observation was not possible, and there was a risk of injury due to the curl of the heater wire during insertion, making it difficult to proceed with the work safely.

The present invention eliminates the drawbacks of the prior art described above,
The purpose of this project is to provide an improved heater wire structure that allows the heater wire to be safely and easily inserted to the bottom of a vertically buried protection pipe where the bottom is closed. , for heater wires installed in bottomed protection pipes buried vertically underground, spacers with circular or elliptical plates slightly smaller than the diameter of the protection pipes are installed at predetermined intervals of the heater wires. is arranged so that the circular or elliptical surface is vertical, and a positive vertical gap is formed between the circular or elliptical surface and the inner surface of the protective pipe. This is due to the structure of the heater wire.

Next, an embodiment of the heater wire structure of the present invention will be further explained with reference to the attached drawings. FIGS. 2 and 3 show an example in which an MI wire (magnesium oxide insulated stainless steel sheathed wire) is used as the heater wire 3. , second
The figure shows an example in which a disk is used as the spacer 5, and FIG. 3 shows an example in which an elliptical plate is used.

As mentioned above, prior to inserting the heater wire 3,
A hole of 30 to 50 m is dug perpendicularly to the soil 2, and a protective pipe 4 with an inner diameter of about 100 mm is inserted to prevent the hole from collapsing.

The bottom of the protective pipe 4 is sealed to prevent water from entering, and from the viewpoint of strength, a copper pipe is preferable.

The protection pipe 4 is usually a standard length of about 5 m and is inserted into the soil one by one while welding with a sleeve etc.
This will form a 50m protective pipe layer.

The heater wire 3 facility is inserted from the ground surface into the protection pipe 4 by its own weight, but at that time, a circular or oval spacer 5 as shown in FIGS. 2 and 3 is placed on the surface of the heater wire 3 in advance. Install it.

The spacer 5 has a diameter slightly smaller than the inner diameter of the protection pipe 4, and is preferably made of a metal plate in terms of mechanical strength and heat resistance.

Ideally, the spacers 5 are installed at intervals of 3 to 5 m, but they may be installed arbitrarily depending on the situation of the facility.

Reference numeral 6 denotes a binding wire for fixing the spacer 5 to the heater wire 3, and from the viewpoint of mechanical strength and heat resistance, a metal material is preferable, but the main purpose is to firmly fix the spacer 5 to the heater wire 3. There are no particular limitations on the material, shape, or fixing method.

In the case of this embodiment, the binding wire 6 is fixed by cross-crossing.

The heater wire structure of this embodiment constructed in this way can be achieved by attaching and inserting a spacer with a diameter slightly smaller than the inner diameter of the protection pipe at an arbitrary position, thereby placing the heater wire in the center of the protection pipe. It becomes possible to do so.

In addition, since the spacer has rounded corners, there is less resistance when inserting the heater wire, which helps prevent injury.It is very effective in applications where the length of the facility is quite deep and visual insertion is not possible. It is something.

Furthermore, the spacer 5 is provided so that its circular or elliptical surface is vertical, and in order to actively form a vertical gap between the spacer 5 and the inner surface of the pipe 4, When inserting the heater wire in the direction, the spacer does not act as resistance to the air in the pipe and increase the insertion resistance.

In this embodiment, an MI wire was used as the heater wire, but any cable having a resistance wire may be used.

The heater wire may be either a two-core type or a single-core folded type, and is not limited to a heater wire for vertical facilities, but may also be for diagonal or horizontal facilities. It is not intended to be interpreted in a limited manner.

As explained above, according to the present invention, the heater wire can be safely inserted into the vertical bottomed protection pipe without causing any damage, and the spacer can be inserted extremely easily within the pipe without experiencing air resistance. The practical benefits of being able to provide a heater wire that is safe and easy to operate at the facility are significant.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing an example of a heating method for an underground low-temperature tank, Figs. 2 and 3 show two embodiments of the heater wire structure of the present invention, A is an explanatory cross-sectional view of each, and B is an explanatory diagram of each. It is a longitudinal cross-sectional explanatory view. 1... Underground buried low temperature tank, 2... Soil, 3...
...Heater wire, 4...Protection pipe, 5...Spacer, 6...Binding wire.

Claims (1)

[Scope of utility model registration request] In heater wires installed in bottomed protection pipes buried vertically underground, spacers with circular or elliptical plates slightly smaller than the diameter of the protection pipes are installed at predetermined intervals of the heater wires. The circular or elliptical surface is provided vertically, and a positive vertical gap is formed between the circular or elliptical surface and the inner surface of the protective pipe. Structure of heater wire.