JPS61116204A - Boiler device preventing corrosion at high temperature of superheater - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] <Industrial Application> The present invention relates to a boiler device, in particular a boiler device for burning a waste liquid called black liquor discharged in a paper manufacturing process to recover heat and recover chemicals contained therein. :Relating to IT equipment.

<Prior art and its problems> When producing pulp, it is necessary to separate the wood components cellulose (fiber) and lignin (resin) to extract only the cellulose. N
a Use chemicals such as S and NaOH. A solution containing dissolved lignin and the above chemicals after pulping processes such as cooking and washing is discharged as a waste liquid called black liquor, but the recovery boiler burns this black liquor to reduce the inorganic chemicals in the black liquor and convert it into Nat.
S and Na1OO! It also collects steam and supplies the steam needed for the pulp process and other equipment.

Figure 1 shows a black liquor recovery boiler.

The boiler main body 1 is provided with an oscillator 12. The oscillator 12 sprays black liquor in the form of coarse particles, and the sprayed black liquor crosses the furnace and adheres to the opposing wall surface, where it is dried by the radiant heat within the furnace. During drying on the wall surface, many bubbles are generated inside the black liquor, and the dried porous solids (char) are successively peeled off from the wall surface and fall to the bottom of the furnace to form charbet 6. The solid content forming the charbet 6 is burned at the bottom of the furnace. By burning the charbet, a molten substance called smelt is generated and discharged from the smelt bout 13 to the outside to recover useful substances such as Na (chemicals).

On the other hand, the high temperature combustion gas rising inside the furnace is transferred to the superheater 2. It passes through the evaporation water pipe 4 and heats the internal fluid.

In recovery boilers, high-temperature corrosion of superheater tubes is often observed due to inorganic salts entrained in combustion gas, so the tube wall temperature must be kept below a certain temperature. For this reason, a shield called a nose baffle 5 is formed in the lower part of the superheater 2 to block radiant heat from the furnace. However, recently, in order to improve the efficiency of boilers, high temperatures and high pressures have been attempted, but for this reason, the superheater 2 has also become larger, and a portion of it protrudes from the nose baffle.

(See Figure 2) Changing the shape of the nose baffle itself would mean major remodeling of the boiler and would have a large effect on the gas flow, so it is virtually impossible. Therefore, in order to properly maintain the temperature of the protruding tube wall of the superheater, a screen tube 3 is formed to cover the superheater (Figures 1 and 2).
Alternatively, measures have been taken such as making the superheater itself have a special structure. Note that the reference numeral 7 is a superheater header.

FIG. 3 shows the case where a screen tube 3 is formed. A part of the screen tube 3 with headers 8 placed at both ends is placed below the superheater 2' to block the radiant heat 14 from the furnace, but if the superheater 2 is thermally deformed 2', )
As a result, complete protection could not be achieved as the device would be directly exposed to the radiant heat 14.

As another method, as shown in FIG. 4, in the superheater 2,
It has also been proposed that the low-temperature tube on the steam inflow side is placed below the superheater main body to form the protective section 2'', and the superheater itself has a radiation heat protection function, but this method does not constitute a superheater. There is a problem that stress is concentrated in a part of the tube, so it is not practical.

In the end, conventional devices cannot fundamentally solve the problem, and the development of more effective protective measures is desired.

<Object of the present invention> The present invention has been constructed in view of the above-mentioned problems, and it is an object of the present invention to provide a boiler device having a structure that can effectively prevent high-temperature corrosion of a superheater.

Summary of Means for Solving the Problems> In short, the present invention connects the screen tube placed at the bottom of the superheater and the superheater so as to absorb stress, and the displacement of the superheater causes the superheater to be protected from radiant heat by the screen tube. This is a boiler device configured to effectively protect the superheater by preventing it from being displaced outside.

<Example> Examples of the present invention will be described below.

In FIGS. 5 and 6, 3 is a screen tube;
A part of it is arranged below the superheater 2 and is configured to block strong radiant heat 14 from the furnace and protect the superheater. Reference numeral 15 designates a superheater locking portion bent upward in the screen tube, and the locking portion 15 and the superheater 2 are connected to each other so as to absorb thermal stress.
This prevents displacement due to heat and prevents the superheater from deviating from the radiation heat protection area provided by the screen tube.

FIG. 6 shows an example of a locking structure between a superheater and a screen pipe. In the figure, reference numeral 10a is a collar (ring-shaped body) attached to the screen tube side, IOb is a collar attached to the superheater 2 side, and the pin 11 is inserted through both collars. Since the collars are arranged with a certain space between them, the superheater 2 is allowed to move in the vertical direction by the locking portion 15 of the screen tube 3, but is restricted from moving in the horizontal direction.

Therefore, the superheater 2 does not come out of the radiation heat protected area by the screen tube, and high-temperature corrosion is prevented.

Here, it is effective to supply steam instead of boiler water as the fluid to the screen pipe 3.

If steam is supplied, good flow within the pipe can be maintained even if the locking portion 15 is formed. That is, when the internal fluid is boiler water, the generated steam stays in the upper part of the locking part 15, and the flow of the internal fluid is inhibited. However, by performing forced circulation, it is possible to ensure the fluidity of the internal fluid even if it is boiler water.

Incidentally, in recent years, there have been accidents in black liquor recovery boilers in which lumps of dust attached to the superheater fall all at once and damage the screen pipes, and in the unlikely event that a large amount of boiler water leaks and falls onto the charbet. It is very dangerous as there is a high risk of it reacting with 49 components and causing an explosion. For this reason, there is a tendency to change the internal fluid of the screen tube to steam, and the configuration of the present invention is consistent with this tendency.

Effects> According to the present invention, high temperature corrosion of the superheater can be effectively prevented.

[Brief explanation of the drawing]

Figures 1 and 2 are cross-sectional views of the black liquor recovery boiler, and Figure 3 (
The figure is a side view of the screen tube, and the figure is A-A.
4 is a side view of a superheater having a self-protection function against radiant heat, FIG. 5 is a side view of a screen tube showing an embodiment of the present invention, and FIG. Detailed view of part B, (b) is a sectional view taken along the O-0 line of (fL). 2...Superheater 3...Screen tube 14...Radiant heat 15...Superheater section Fig. 3 Fig. 4

Claims (1)

[Claims] 1. In a structure in which a screen pipe is arranged at the lower part of the superheater hanging down from the header to block radiant heat to the superheater, a part of the screen pipe is bent to lock the superheater. A boiler device for preventing high-temperature corrosion of a superheater, characterized in that the superheater locking part and the superheater are connected to each other so as to restrict horizontal displacement of the lower part of the superheater. 2. A boiler device for preventing high-temperature corrosion of a superheater according to claim 1, characterized in that the fluid supplied to the screen pipe is steam.