JP4133676B2 - Boiler with water supply path backflow prevention structure - Google Patents

Description

  The present invention relates to a boiler having a water supply path backflow prevention structure.

As described in FIG. 2 which is a conventional example and Japanese Patent Application Laid-Open No. 2002-139202, a water supply path 4 is connected to a return water pipe 3 that connects the steam separator 2 and the boiler body 1 in a once-through boiler, There is a boiler that supplies water through the return pipe 3. When normal temperature water is supplied, the anticorrosive effect due to chemicals cannot be fully exhibited at normal temperature, but the boiler water flowing through the return water pipe is hot, so the water supply temperature can be achieved by supplying water to the return water pipe 3. Increases immediately, and the efficacy of the drug can be exerted in a short period of time. Control of water supply is performed based on the water level in the boiler detected by the water level detection device 13. When the water level in the boiler decreases to the water supply start water level, the water supply pump 12 is activated to start water supply and rise to the water supply stop water level. Control to stop the water supply pump and stop the water supply. In this case, since there is a flow of water flowing to the boiler in the water supply path during water supply, the boiler water cannot flow back to the water supply path 4. However, when the water supply is stopped, the boiler water has a high pressure, and therefore, the boiler water may flow back to the water supply path 4. Therefore, a check valve 5 is provided near the end of the water supply path 4 to prevent the boiler water from flowing backward. Since the check valve may come into contact with boiler water, and the boiler water is hot, the check valve must have high resistance to high temperatures.
JP 2002-139202 A

  The problem to be solved by the present invention is to prevent the check valve provided near the end of the water supply path from being exposed to high-temperature boiler water and improve the durability of the check valve.

  Through a boiler body that heats water to generate steam, an air-water separator that separates steam taken out from the boiler body, and a return pipe that returns the liquid separated by the steam separator to the boiler body In each boiler that has a water supply path connected to the return water pipe to supply water to the boiler body, a check valve is provided near the end of the water supply path, and the check valve is installed between the check valve and the return water pipe. A U-shaped pipe is provided below the vertical position and the return water pipe connecting part height position of the water supply path.

  By implementing the present invention, the check valve near the end of the water supply path is not exposed to high-temperature boiler water, and the durability of the check valve can be improved. There is an advantage that the restriction of having to be eliminated is also eliminated.

  FIG. 1 is a schematic diagram of a boiler implementing the present invention. The boiler body 1 has a structure in which an upper header 7 is provided at the upper part, a lower header 8 is provided at the lower part, and a plurality of heat transfer pipes 9 are connected between the upper and lower headers, and a combustion device 10 is provided at the upper center. . A steam communication pipe 11 is connected to the upper header 7, and a steam / water separator 2 is provided at the other end of the steam communication pipe 11. The steam-water separator 2 has a return water pipe 3 connected to the lower part, and the return water pipe 3 is connected to the lower header 8 of the boiler body 1. A water supply path 4 is connected in the middle of the return water pipe 3, a check valve 5 is provided near the end of the water supply path 4, and a check valve is provided between the check valve 5 and the return water pipe 3 of the water supply path 4. 5 A U-shaped pipe 6 is provided below the installation height position and the return water pipe 3 connecting portion height position of the water supply path 4.

  Water is supplied to the boiler body 1 through the water supply path 4 and is fed into the lower header 8 through the check valve 5, the U-shaped pipe 6 and the return water pipe 3. The water that has entered the lower header 8 is dispersed into the heat transfer tubes 9, and steam is generated in the heat transfer tubes 9 by heating the heat transfer tubes 9 by the combustion device 10. The steam generated in the heat transfer tube 9 gathers in the upper header 7 and then enters the steam / water separator 2 through the steam communication tube 11. Since the steam sent to the steam separator 2 contains a large amount of liquid, it is separated into steam and liquid by the steam separator, and the steam with increased dryness is taken out from the upper part of the steam separator 2, The separated liquid is circulated through the return water pipe 3 to the lower header 8.

  Water supply control is performed by operating the water supply pump 12 of the water supply path 4 based on the water level in the boiler detected by the water supply control device 14 by the water level detection device 13. When the boiler water level drops to the water supply start water level, the water supply control device 14 starts the water supply to the boiler by operating the water supply pump 12, and when the boiler water level rises to the water supply stop water level, the water supply control device 14 supplies the water supply pump 12. To stop water supply to the boiler. When the feed water pump 12 is in operation, the feed water pump 12 sends water at a pressure higher than the pressure in the boiler, so the water in the feed water path 4 flows toward the boiler, and the boiler water flows from the boiler to the feed water path 4. There is no backflow.

  When the water supply pump is stopped, the flow of water supply in the water supply path 4 is stopped, and water is collected in the U-shaped pipe 6. Since the boiler water is high in temperature and has a small specific gravity, and the feed water is low in temperature and has a larger specific gravity than the boiler water, the feed water stored below the U-shaped pipe 6 and the boiler flowing from above The water is not changed, and the boiler water does not enter the U-shaped pipe 6. Therefore, as long as the check valve 5 is functioning normally, the hot boiler water does not flow back to the upstream side of the water supply path 4 from the U-shaped pipe 6, and the check valve 5 is not hot. You will never be touched.

  When the water supply path 4 is a conventional one without the U-shaped pipe 6, when the operation of the water supply pump is stopped, the water supply and boiler water are mixed on the downstream side of the check valve 5 in the water supply path 4. Valve 5 was to be exposed to hot boiler water. However, the provision of the U-shaped pipe 6 prevents the check valve 5 from being exposed to high temperatures, thereby improving the durability of the check valve and eliminating the need for durability against high temperatures. The restriction of having to be a type of check valve is also eliminated.

Outline diagram of boiler implementing the present invention Overview of conventional boiler

Explanation of symbols

1 Boiler body
2 Air-water separator
3 Return pipe
4 water supply routes
5 Check valve
6 U-shaped piping
7 Upper header 8 Lower header 9 Heat transfer tube 10 Combustion device 11 Steam communication tube
12 Water Supply Pump 13 Water Level Detection Device 14 Water Supply Control Device

Claims (1)

Through a boiler body that heats water to generate steam, an air-water separator that separates steam taken out from the boiler body, and a return pipe that returns the liquid separated by the steam separator to the boiler body In each boiler that has a water supply path connected to the return water pipe to supply water to the boiler body, a check valve is provided near the end of the water supply path, and the check valve is installed between the check valve and the return water pipe. A boiler having a water supply path backflow prevention structure characterized in that a U-shaped pipe is provided below the vertical position and the return water pipe connection portion height position of the water supply path.

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