JP-7855975-B2 - Corrosion prevention structure for joints between flange sections

JP7855975B2JP 7855975 B2JP7855975 B2JP 7855975B2JP-7855975-B2

Inventors

十川郁夫
木下博之
重岡潤一

Assignees

中国電力株式会社

Dates

Publication Date: 20260511
Application Date: 20220907

Claims (1)

A structure for preventing corrosion at the joint between flange portions, One of the flange portions to be joined is, A water level detection device, which has a container that communicates with the steam drum of a boiler via two piping systems and detects the water level of the steam drum by utilizing the buoyancy of a float housed inside the container, is connected to the piping system by a first flange portion, The other flange portion of the flange portions to be joined together is The second flange portion is for connecting the on-off valves, which are provided in the outdoor piping sections of the two aforementioned piping systems and which open and close the flow path of the piping system by the displacement of the valve stem, to the water level detection device. Both of the on-off valves provided in the piping sections of the two aforementioned piping systems are arranged such that the direction in which the valve stems are displaced is horizontal or substantially horizontal. Furthermore, the corrosion prevention structure for the joint portion between flange portions is characterized in that a cover member is provided on both the piping portions of the two piping systems, extending from the location of the on-off valve to the container of the water level detection device, and covering the piping portion including the on-off valve and the first and second flange portions, and is formed into a cylindrical shape by joining a plurality of arc-shaped members, with the joining position for forming the cylindrical shape of the arc-shaped members being on the side.

Description

This invention relates to a structure for preventing corrosion due to rainwater intrusion at the joint between a flange portion for connecting an on-off valve and a flange portion for connecting a water level detection device, which are part of a piping system that connects a steam drum of an in-house boiler to a water level detection device. The on-site boilers of power generation facilities have a water level detection device for detecting the water level in the steam drum located above the boiler, as shown in, for example, Patent Document 1. This water level detection device may be of a type that detects and notifies of changes in water level by utilizing the vertical movement due to the buoyancy of a float and the attraction and detachment of a magnet (hereinafter referred to as the float type). Such a float type water level detection device has at least a container housing the float, and as shown in, for example, Patent Document 1, the upper side of the container is connected to the upper part of the steam drum via the steam-side piping system, and the lower side of the container is connected to the lower part of the steam drum via the boiler water-side piping system. Each piping system is equipped with an on-off valve, as shown in, for example, Patent Document 1. In some cases, the piping portion of this system equipped with the on-off valve extends outdoors. The water level detection device container and the on-off valves of each piping system are connected by joining the flange surfaces of the flange portions. Each piping system is then covered with a cover member, such as an insulating cover, extending from around the on-off valve to both flange portions connecting to the water level detection device container. Furthermore, the cover member, such as the insulating cover, is secured by metal fittings. Japanese Patent Application Publication No. 10-185108 This is a schematic diagram illustrating the configuration of a steam drum, a water level detection device, and two piping systems connecting the steam drum and the water level detection device of an in-house boiler to which the present invention can be applied.The diagram provides a schematic overview of the configuration of a water level detection device to which the present invention can be applied, with (a) showing the state in which the water level in the container of the water level detection device is normal, and (b) showing the operation when the water level in the container of the water level detection device falls below (a).This is a schematic perspective view showing the container of the water level detection device, a laterally extending pipe section located outdoors in one of the two piping systems, and the on/off valve provided in the said pipe section, all covered by a cover member.This is a schematic front view showing the container of the water level detection device, the piping portion of the two piping systems located outdoors, and the on-off valve provided in the piping portion, with the piping portion and the on-off valve covered by a cover member.This is a schematic front view showing the container of the water level detection device, the piping portion of the two piping systems located outdoors, and the on/off valve provided in the piping portion, with the cover member removed from the state shown in Figure 4.This is an explanatory diagram showing an example of an on-off valve to which the present invention can be applied, where (a) shows the external appearance of the on-off valve and (b) shows the internal structure of the on-off valve.This is an explanatory diagram illustrating the flow of rainwater when the aforementioned on-off valve is covered by a cover member. The embodiments of the present invention will be described below with reference to the drawings. Figure 1 shows an example of a boiler to which this invention can be applied: an in-house boiler 1 used in power generation facilities such as thermal power plants. The in-house boiler 1 is installed, for example, to supply steam (auxiliary steam) to a predetermined steam usage point (e.g., a turbine shaft seal) during the startup and shutdown of the power generation facility. The in-house boiler 1 is composed of a steam drum 2 (also referred to as a steam drum, etc.; hereinafter the same) located above it, a water drum 3 (also referred to as a water drum, etc.; hereinafter the same) located below it, and a boiler body 4 located between these drums 2 and 3. The steam drum 2 is for extracting steam, and generally, under proper conditions, the lower half is filled with water and the upper half with steam. To prevent malfunctions in the in-house boiler 1 due to the water level in the steam drum 2 deviating from the proper state, the in-house boiler 1 has a water level detection device 5 that detects the water level in the steam drum 2. The steam drum 2 and the container 51 of the water level detection device 5 are connected by two piping systems 7 and 8. The upper of the