JPS6141516Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a drain attack prevention device installed in branch pipes such as drain vent pipes, air vent pipes, sampling take-out pipes, and pressure detection pipes that branch from a high-temperature steam main pipe in a thermal power plant or the like.

In the conventional type, the branch pipe was simply attached to the main pipe via the nozzle stand.

The condensed condensate stagnant inside the branch pipe may self-evaporate due to changes in the pressure inside the branch pipe (mainly when it decreases), or the condensate at saturated temperature may drip back to the main pipe side and flow back to the main pipe base and As a result of repeated rapid cooling and thermal shock to the inner surface of the main tube near the nozzle stub, cracks have formed on the nozzle stub and the inner surface of the main tube near the nozzle stub. For this reason, although various improvements have been made to the shape of branch pipes in order to prevent cracks from occurring, the current situation is that no cracks have been completely eliminated.

Therefore, if it is impossible to eliminate the cracking phenomenon that occurs frequently at present, this invention aims to change the place where the crack occurs, that is, to repair or remodel the problem, which cannot be repaired without spending a lot of time and money. This was developed with the purpose of providing a device that can prevent cracks on the inner surface of the pipe or the inner surface of the nozzle welded to the main pipe, and generate cracks in places where they can be easily repaired even if cracks occur. The idea is that a drain attack prevention device is placed in the middle of a branch pipe that branches from the main pipe, and includes an inner cylinder whose one end is connected to the end of the branch pipe on the main pipe side and whose other end is sealed. an outer cylinder that surrounds the main tube and has one end connected to the end of the branch pipe on the side opposite to the branch pipe on the side of the main pipe, and a plurality of holes are provided in the inner cylinder located in the outer cylinder, This invention provides a drain attack prevention device characterized by having a drain blow pipe attached to the lower part of an outer cylinder.

According to the device of the present invention, it is possible to prevent condensed drain flowing backward or dripping through the branch pipe from flowing toward the main pipe,
Even if there is a backflow, it has the function of discharging condensed condensate from the blow pipe to the outside of the system, so the cracks that often occur in the past do not occur on the inner surface of the main pipe or the inner surface of the main pipe nozzle stand, and instead cracks occur. If so, it is the inner and outer cylinders of the drain attack prevention device or the branch pipes near the device, and by regularly inspecting the device or considering the device as a consumable item and replacing it regularly, you can avoid critical situations such as conventional plant operation shutdowns. I can do it.

Next, the present invention will be specifically explained based on an embodiment shown in the drawings.

A nozzle stub 2 is welded to the main pipe 1, and a branch pipe 3 is further welded and attached to the nozzle stub 2. Main tube 1
A perforated inner cylinder 4 is attached to the side branch pipe 3 by welding. A branch pipe 3 is provided on the outer periphery of the perforated inner cylinder 4.
An outer cylinder 6 having a diameter larger than the diameter of the outer cylinder 6 is provided.
is connected to the branch pipe 3 on the side opposite to the branch pipe 3 on the side of the main pipe 1 via the reducer 7 . Hollow inner tube 4
A cap 5 is attached to the tip. The cap 5 is a flat plate or hemispherical blind cap, but depending on the installation orientation of the device, an extremely small diameter air vent hole may be provided at the top, and the perforated inner cylinder 4 secures the inner diameter area of the branch pipe 3. The holes may have a small diameter so as to have an area of 200 mm or more, and the size, shape, and number of the holes may be any size. Further, the outer cylinder 6 and reducer 7 may have any shape, whether circular or square. A blow pipe 8 having a stop valve and a drain trap in the middle is provided at the lower part of the outer cylinder 6.

In the case of conventional branch pipes without a drain attack prevention device, the condensed condensate in the branch pipe would reach the main pipe directly, but by installing the drain attack prevention device, the condensate that drips down the branch pipe 3 and flows backwards. The drain passes through the hole in the hollow inner cylinder 4 to the main pipe 1.
Since the drain is discharged from the system via the blow pipe 8 from the drain hole provided at the bottom of the outer cylinder 6 before reaching the drain hole, no drain attack is caused to the nozzle stub 2 and the main pipe 1. In the unlikely event that cracks occur first due to drain attack, it is the inner and outer cylinders 4 and 6.
Since the inner and outer cylinders 4 and 6 are simply welded to the branch pipe 3, inspection and replacement are extremely easy.

In this embodiment, the branch pipe 3 is attached to extend upward from the main pipe 1, but the present invention can also be applied to a structure in which the branch pipe 3 extends downward or laterally.

[Brief explanation of the drawing]

The figure is a front sectional view of one embodiment of the present invention. 1...Main pipe, 2...Nozzle stand, 3...Branch pipe, 4...
...Inner cylinder with holes, 5...Cap, 6...Outer cylinder, 7...
...Reducer, 8...Blow tube.

Claims (1)

[Scope of utility model registration request] In a drain attack prevention device placed in the middle of a branch pipe branching from the main pipe, one end is connected to the end of the branch pipe on the main pipe side, and the other end is a sealed inner cylinder, surrounding a part of the inner cylinder. , an outer cylinder having one end connected to a branch pipe on the main pipe side and an end of the branch pipe on the opposite side, a plurality of holes being provided in the inner cylinder located in the outer cylinder, and a lower part of the outer cylinder A drain attack prevention device characterized by having a drain blow pipe attached to the drain attack prevention device.