JPH0412328Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a superheat reducer for various boilers.

Conventionally, a typical boiler has a furnace 2, superheaters 3, 4, desuperheater 5, boiler water pipe 6, economizer 7, water supply pipe 8, main steam pipe 10, as shown in FIG. The fuel 1 used in the boiler is put into the furnace 2 together with combustion air (not shown) as shown by the arrow, combustion is completed in the furnace 2, and the combustion gas is radiated. It is discharged through the superheaters 3 and 4, which are convection heat transfer surfaces, the boiler water pipe 6, which is a convection heat transfer surface, and the energy saver 7.

On the other hand, the water supplied to the boiler is led from the feed water pump outlet to the water supply pipe 8 as shown by the arrow, passes through the economizer 7, and enters the steam drum at the upper part of the boiler water pipe 6.
The water that has entered the boiler is evaporated in the furnace 2 and boiler water pipe 6, and the generated steam is led from the steam drum to superheaters 3 and 4 where it is superheated, and then from the main steam pipe 10 to the steam turbine (not shown). ) or vented to the factory air line.

In such a boiler, the temperature of the generated steam fluctuates with the boiler load (generally decreases with the boiler load), and when a variety of fuels are used, it tends to fluctuate greatly depending on the fuel.

On the other hand, the side that uses the generated steam (steam turbine or factory air supply line) requires that steam be always supplied at a constant temperature, so on the boiler side, in order to control the steam temperature, the area of the superheater is reduced. A desuperheater 5 is provided between the superheaters in order to increase the size and raise the temperature higher than the specified temperature, and a portion of the water supplied in the water supply pipe 8 to the boiler is injected into the desuperheater 5. , the steam temperature is kept at a specified value. This control is controlled by a valve 9 that measures the output steam temperature with a detector 11 and controls the amount of water injected.

The superheat reducer has a structure as shown in FIG.
A water injection nozzle 21 is inserted, and water 24 is injected from the water injection nozzle 21 into the steam 25 of the communication pipe 20 as shown by the arrow, and the temperature of the steam is lowered using the evaporation heat of the injection water.

In this way, water is injected into the superheated steam,
Water may come into contact with the inner surface of the communication pipe 20 through which steam passes, and in order to protect such an inner surface of the communication pipe 20, an internal protection cylinder 22 is generally installed downstream of the water injection nozzle 21 of the communication pipe 20. It is installed inside to protect the connecting pipe 20.

However, when water is injected into steam in this way, the distance it takes for the water to complete evaporation depends on the amount of injection and the size of the water droplets, but as shown in Figure 3, Between the distance from the water injection position and the spray water remaining percentage, as the water injection amount increases from a to b to c, the spray water remaining percentage tends to increase, and the steam distance is relatively long, Even if the temperature on the downstream side of the water injection point is actually measured by the detector 23, only the temperature of the evaporated water is often measured.

If it takes a long distance for the water to evaporate, you can lengthen the inner protection tube 22 and connect the connecting tube 2.
0 is protected, but this requires the provision of a connecting pipe 20 that extends beyond the furnace width of the boiler, which is undesirable from both a structural and cost standpoint.

Furthermore, if the length of the internal protection tube 22 is insufficient, the inner surface of the communication tube 20 in the area without the protection tube 22 will be partially or intermittently cooled, and a temperature change will occur in this area. However, there were drawbacks such as the possibility of destruction due to thermal fatigue during long-term operation.

The present invention solves the above-mentioned conventional drawbacks, and aims to complete the evaporation of water injected as quickly as possible in the desuperheater, making it structurally compact, and reducing the temperature change on the inner surface of the steam pipe that communicates with the superheated pipes. The purpose is to effectively arrange and use the protective tube in order to minimize the size of the protective tube.

In order to achieve the above object, the present invention provides a bent part downstream of the water injection part in a superheat reducer installed in a steam pipe that communicates between superheaters of a boiler,
A protection tube is disposed on the inner surface of the curved portion, and the water is forcibly evaporated by the protection tube.

Embodiments of the present invention will be described below with reference to the drawings.

Figure 4 shows the first embodiment of the present invention.
0 is a water injection nozzle of a normal desuperheater for water injection 48, 41 is a steam pipe that communicates between superheaters, 42
43 is a metal fitting that fixes the protection tube 42 to the steam pipe 41.

The length of the protective tube 42 is about 3 m as before, and the steam pipe 4 is placed as close as possible downstream of the protective tube 42.
One bent part 44 is provided, and a protection cylinder 45 is provided in this bent part 44. The shape of the protective tube 45 of the bent portion 44 is made into a vent pipe in accordance with the shape of the bent portion.

Figure 5A shows a second embodiment of the present invention.
The bent portion 46 is T-shaped, and a protective tube 47 housed in the bent portion 46 represents a T-piece tube. The protection tube 47 has a structure in which a portion of the upstream side is cut out, as shown in FIG. 5B. Other parts are the same as in FIG.

Moreover, various shapes of the protective tube can be adopted depending on the shape of the bent portion.

FIG. 6 shows a third embodiment of the present invention, in which the protective tube for the bent portion has a double structure. That is, 61 is a normal-shaped protection tube installed inside the bent part, but there is another protection tube 6 inside this protection tube 61.
2, and by making a large number of holes in the protective tube 62, it is possible to increase the area of the protective tube with which unevaporated moisture comes into contact.

As mentioned above, by providing the bent parts 44 and 46 downstream of the water injection part of the desuperheater and arranging the protective cylinders 45, 47, 61, and 62 on the inner surface of this bent part,
While the steam passes through the steam pipe 41, water is injected from the water injection nozzle 40 and the water evaporates, and the unevaporated water is forced to collide with the protective tubes 45, 47, 61, 62 to quickly evaporate, and the steam pipe 41 This prevents the water from coming into contact with the inner surface of the

By configuring the present invention as described above,
The evaporation of the water injected into the desuperheater is not only caused by the evaporation of water droplets in the steam, but also by bringing the steam into contact with the protective tube at the bend, which promotes evaporation and therefore shortens the distance it takes to complete evaporation. ,
It can be a compact attemperator.

[Brief explanation of the drawing]

Figure 1 is a schematic side view of a typical boiler, Figure 2 is a longitudinal cross-sectional view of a conventional attemperator, and Figure 3 shows the relationship between the distance from the water injection position of the superheater and the remaining proportion of spray water. 4 is a vertical cross-sectional view of a superheat reducer showing the first embodiment of the present invention, and FIG. 5A is a longitudinal cross-sectional view of the superheat reducer showing the second embodiment of the present invention.
FIG. 5B is a view taken along the line A--A in FIG. 5A, and FIG. 6 is a longitudinal cross-sectional view of a protective tube of a superheater showing a third embodiment of the present invention. 40...Water injection nozzle, 41...Steam pipe, 42,
45, 47, 61, 62...Protective tube, 43...Hardware, 44, 46...Bent part.

Claims (1)

[Scope of utility model registration request] A superheat reducing device installed in a steam pipe that communicates superheaters of a boiler with each other, the superheat reducing device being characterized in that a bent portion is provided on the downstream side of a water injection portion, and a protective cylinder is provided on the inner surface of the bent portion.