JPS6231993Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a well-inserted preheater.

In this specification, a well-inserted preheating heater (hereinafter simply referred to as a heater) refers to a heater that is inserted into a well tube installed along the outer surface of a pipe in advance to preheat the pipe.

Since this heater is used by being inserted into the well tube, there are various problems that need to be solved.

(a) Since the piping route is installed directly, the well tube installed along the piping and the well tube installed along the complicated route take a complicated route, and the total length of the pipe is also It is long and requires sufficient flexibility.

(b) Since the preheating temperature of piping is normally around 200 to 300°C, the temperature of the inserted heater is expected to exceed 400°C, so it needs to have a heat resistance of 500°C or higher.

(c) Of course, it can be inserted into the well tube, but
After being inserted into the well tube, it needs to be easily pulled out of the well tube.

(d) When there is a temperature gradient along the length of the piping, for example in the case of sodium piping in a nuclear reactor, the temperature of the piping on the reactor vessel side rises due to heat conduction from the reactor, but the temperature outside the reactor vessel is preheated. When not heated by a heater, it is at room temperature, and in order to preheat uniformly in the longitudinal direction of the piping with one heater, it is necessary to be able to adjust the output distribution.

(e) Frictional force, bending stress, and torsional force are applied to the heater when inserting the heater into the well tube or pulling it out from the well tube, so mechanical strength is also required.

The object of the present invention is to provide a well-inserted preheater that satisfies the above requirements, and the present invention will be described below with reference to examples.

FIG. 1 is a partial sectional view of an embodiment of the present invention.

1 is a spherical plug, a hole is provided in the center of the spherical plug 1, a core wire 2 is inserted into the hole, and the core wire 2 is inserted into the hole.
and the tip of the spherical plug 1 are welded together.

On the other hand, a coil 3 made of a heat-resistant metal such as Inconel is welded to the surface of the cylindrical portion of the plug 1.

In this case, since the coil 3 has flexibility, it can be easily inserted into the well tube 5.

Also, the heater 4 is placed on the outside of the coil 3 at a predetermined pitch.
is wound into a coil, and one end of the heater coil 4 is connected to the tip of the coil 3 on the plug 1 side.

The well-inserted preheater configured as described above maintains flexibility as a whole even when the heater 4 is placed outside the coil 3, and even if the well tube is bent, the coil 3 can be pushed in. This allows the heater 4 to be inserted into the well tube 5 at the same time.

Furthermore, by winding the heater 4 on the outside of the coil 3, the thermal resistance between the heater 4 and the well tube 5 can be reduced. If the coil 3 is provided outside the heater 4, the thermal resistance of the coil 3 will be added, and the temperature difference between the well tube and the heater will increase by this amount. However, heater 4 has coil 3
Since the heater 4 is provided outside the heater 4, the temperature of the heater 4 is lowered and it is safe from the temperature.

Next, other embodiments of the present invention will be described.

FIG. 2 is a partial sectional view of another embodiment of the present invention.

In this embodiment, as shown in FIG.
A heat-resistant wire 6 made of, for example, Inconel is wound in a coil shape between the heater 4 wound in a coil shape on top, and a coil of the heater 4 and a coil of the heat-resistant wire 6 are placed on the coil 3. and are wound in close contact with each other.

Therefore, between the heaters 4 wound at a predetermined pitch, there is a heat-resistant wire 6 wound in a coil shape, which is similar to tightly wound winding, and there is an effect that pitch unevenness of the coil around the heater 4 is eliminated. Even in this case, the flexibility of the intercalated preheater is not lost.

As explained above, according to the present invention, it has sufficient flexibility, requires sufficient temperature resistance, and can be easily inserted into and removed from the well tube. The drawing can be done by applying a tensile force to the core wire, and the main part of the insertion type preheater will not be stretched. It also has sufficient mechanical strength.

[Brief explanation of drawings]

FIG. 1 is a partial sectional view of an embodiment of the present invention. Second
The figure is a partial sectional view of another embodiment of the present invention. 1: plug, 2: core wire, 3: coil, 4: heater, 5: well tube, 6: heat-resistant wire.

Claims (1)

[Scope of utility model registration request] a tip plug, a close-contact coil made of a heat-resistant wire and having one end fixed to the tip plug, and a heater wound in a coil shape at a predetermined pitch on the coil;
A well-inserted preheater comprising a core wire having one end fixed to the tip plug and passing through the coil.