JP2934528B2 - Rust prevention equipment for dust collectors - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rust prevention treatment device for a dust collector.

[0002]

2. Description of the Related Art In a dust collector used in a thermal power plant or the like, ash (ash) floating in a gas by a metal dust collecting plate and a discharge electrode disposed inside the dust collecting plate is electrically applied to the dust collecting plate. Attached to and collected. Removal of the ash attached to the dust collecting plate is usually wiped off by a hammering device,
At the time of internal inspection or maintenance after the plant is stopped, cleaning is performed by spraying washing water from a nozzle mounted on the inner surface of the ceiling of the dust collector in order to clean residual ash.

[0003]

By the way, in the case of an oil-fired boiler, the main component of the ash adhering to the dust collecting plate is ammonium sulfate ((NH ₄ ) ₂ SO ₄ ) or acidic ammonium sulfate (NH ₄ HSO ₄ ). Is an acidic component of Therefore, if the amount of the washing water applied when removing the ash attached to the dust collecting plate is insufficient and ash remains on the dust collecting plate, the acidic components of the ash become wet and the dust collecting plate becomes wet. There is a problem of corrosion. On the other hand, in the case where a sufficient amount of washing water is sprayed so that ash does not remain on the dust collecting plate, it is difficult to determine when to end the spraying of the washing water, and when a sufficient amount of washing water is sprayed. Even if ash adhering to the dust collecting plate is removed, there is a problem that the metal surface inside the dust collector corrodes during a long-term plant stop due to a trace amount of acidic components remaining in the dust collector.

[0004] The present invention has been made to solve the conventional problems, and a rust prevention treatment apparatus for a dust collector that can reliably and efficiently prevent corrosion inside the dust collector after the plant is stopped. It is intended to provide.

[0005]

According to the present invention, there is provided a spray nozzle mounted in a dust collector, cleaning water supply means for supplying cleaning water to the spray nozzle, and A pH measuring device for measuring the pH value of the discharged liquid, and a rust preventive agent supply means for supplying a rust preventive agent to the spray nozzle based on the pH value of the discharged liquid, This is a rust prevention treatment device for dust collectors.

Examples of the rust preventive include sodium nitrite (NaNO ₂ ), sodium chromate (Na ₂ CrO ₄ ),
Composed of an inorganic compound such as hydrazine (N ₂ H ₄ ),
Alternatively, a material composed of an organic compound such as dicyclohexylammonium nitrite used as a vaporizable rust preventive (VPI, VCI) is exemplified.

[0007]

According to the rust-prevention treatment apparatus of the dust collector of the present invention, the cleaning water is supplied to the spray nozzle mounted in the dust collector by the cleaning water supply means, so that the dust is collected from the spray nozzle. Spray the washing water inside. At this time, the pH value of the effluent (wash water) from inside the dust collector is measured by the pH meter, and it can be detected from this pH value that the ash attached to the dust collecting plate has been sufficiently removed. After confirming the completion of the washing by such pH measurement, the spraying of the washing water is stopped, and a rust preventive agent is supplied to the spraying nozzle by the rust preventive agent supply means. Spray rust preventive on metal surfaces such as dust collectors and discharge electrodes. At this time, the pH value of the effluent (rust inhibitor) from the inside of the dust collector is measured by the pH meter, and it can be detected from this pH value that the rust preventive agent is sufficiently distributed in the dust collector. .

Therefore, after sufficiently removing the ash adhering to the dust collecting plate in the dust collector, the plant is further sprayed with a rust preventive on metal surfaces such as the dust collecting plate and the discharge electrode in the dust collector. After the stop, the inside of the dust collector can be reliably prevented. Moreover,
The timing for terminating the application of the washing water and the rust inhibitor can be grasped, and the application of the washing water and the rust inhibitor can be minimized, so that the running cost can be reduced.

[0009]

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

FIG. 1 is an explanatory view showing a rustproofing device for a dust collector according to this embodiment. That is, 1 in the figure is a dust collector.
As shown in FIGS. 2 and 3, two dust collecting plates are arranged on the same line along the flow direction of the boiler gas 2, as shown in FIGS.
8 are arranged in parallel, and five discharge electrodes 4 are arranged at regular intervals in the flow direction between the dust collecting plates 3 facing each other. The dust collecting plate 3
Has a structure in which both ends of a plurality of iron plates 3a are bent and engaged with each other as shown in FIG.

A plurality of spray nozzles 5 are mounted on the inner surface of the ceiling of the dust collector 1 so that washing water and the like can be sprayed to all areas in the dust collector 1. Spray nozzle 5
Is connected by a pipe 7 to a supply source 6 of industrial water as washing water. The first pipe 7 is connected to the first
Second valves 8, 9 are interposed sequentially. The industrial water supply source 6, the pipe 7, and the first and second valves 8 and 9 constitute cleaning water supply means.

In the figure, reference numeral 10 denotes sodium nitrite (NaN).
O ₂ , a rust inhibitor) A tank containing a rust inhibitor solution 11 in which 2 to 5% by weight is dissolved. This tank 10 has a stirrer 12
Is provided. The tank 10 has a rust inhibitor supply source 13
A rust preventive is supplied through a pipe 14 from the container. The pipe 14 is provided with a third valve 15. The water of the industrial water supply source 6 is stored in the tank 10 with the supply source 6 and the first water.
The gas is supplied through a pipe 16 branched from the pipe 7 located between the valve 8. The pipe 16 is provided with a fourth valve 17. Steam from a heat source 18 is supplied to the tank 10 through a pipe 19, and
A valve 20 is interposed. A pipe 21 is mounted near the bottom of the tank 10, and the other end of the pipe 21 is connected to the pipe 7 located between the first and second valves 8 and 9. A sixth valve 22, a liquid feed pump 23, and a seventh valve 24 are sequentially provided in the pipe 21 from the side of the connection with the tank 10. These tank 10, sixth valve 22,
The pipe 7 from the connection part with the liquid feed pump 23, the seventh valve 24, the pipe 21 to the connection part with the spray nozzle 5, and the second valve
9 constitutes the rust preventive agent supply means.

An exhaust port 25 is provided at the bottom of the dust collector 1. The outlet 25 is connected to a waste liquid treatment facility 26 by a pipe 27.
Are connected by A pipe 27 near the outlet 25 has p
An H measuring device 28 is mounted, and an eighth valve 29 is interposed at a position below the mounting portion of the pH measuring device 28. A pipe 30 branches off from the pipe 27 located between the mounting portion 30 of the pH measuring device 28 and the eighth valve, and the other end of the pipe 30 is connected to the tank 10. A ninth valve 31 and a circulation pump 32 are sequentially provided in the pipe 30 from the side of the connection with the pipe 27.

Next, the operation of the rust preventive treatment apparatus for a dust collector will be described with reference to FIG. 1 to FIG. 4 and FIG. 5 showing a change in the pH value of the effluent from the dust collector.

During operation of the plant, a large amount of ash composed of acidic components such as ammonium sulfate and acidic ammonium sulfate in the boiler gas 2 adheres to the dust collecting plate 3 of the dust collector 1.

After stopping the plant, the first and second valves
8 and 9, the water from the industrial water supply source 6 is supplied to the plurality of spraying nozzles 5 through the pipe 7, and the washing water (industrial water) is sprayed from each spraying nozzle 5 into the dust collector 1. At this time, the pH value of the effluent from the inside of the dust collector 1 is measured by the pH meter 28.
Measure with The pH value of the measured effluent is, for example, as shown in FIG.
As shown in (1), in the initial stage of spraying the washing water, the ash attached to the dust collecting plate 3 is on the acidic side (pH 3 to 4) because it is dissolved in the discharged liquid (washing water). When the ash adhering to the dust collecting plate 3 is sufficiently removed and neutralized (p
H7) is reached. After detecting that the discharged liquid has become neutral as described above, the first valve 8 is closed to stop spraying the washing water. If hot water supplied from a hot water supply source (not shown) connected to the pipe 7 is used as the washing water, it is possible to more effectively remove ash attached to the dust collecting plate 3. Become.

Next, by opening and closing the third and fourth valves 15 and 17, a rust inhibitor and water are supplied into the tank 10 to prepare a rust inhibitor solution 11 having a concentration of 2 to 5% by weight. Subsequently, the sixth and seventh valves 22 and 24 are opened, and the liquid feeding pump is opened.
By operating 23, the rust inhibitor solution in the tank 10
11 is supplied to the plurality of spray nozzles 5, and a rust preventive solution 11 is sprayed from each spray nozzle 5 into the dust collector 1 to perform a rust preventive treatment. At this time, the pH of the effluent from the dust collector 1
The value is measured by the pH meter 28. The pH value of the effluent to be measured is near neutral, for example, as shown in FIG. 5, since the washing water sprayed earlier is discharged from the dust collector 1 at the initial stage of spraying the rust inhibitor solution. When the spraying of the rust preventive solution proceeds and the alkaline rust preventive solution spreads in the dust collector 1, the pH reaches the point B where the pH value of the rust preventive solution is reached. After detecting that the discharged liquid has reached the pH value of the rust preventive solution, the liquid feed pump 23 is stopped, and the sixth and seventh valves 22 and 24 are closed to close the rust preventive solution. Finish spraying. If the fifth valve 20 is opened and steam is supplied from the heat source 18 into the tank 10 to heat the rust inhibitor solution 11, the metal surface in the dust collector 1 is more effectively rust-proofed. It becomes possible. The discharged liquid from the discharge port 25 of the dust collector 1 is supplied to the tank 10 again by closing the eighth valve 29, opening the ninth valve 31 and operating the circulation pump 32 to supply the discharged liquid to the tank 10. Of the rust inhibitor solution components can be circulated and used. On the other hand, unnecessary effluent can be supplied to the waste liquid treatment equipment 26 and processed by opening the eighth valve 29 and closing the ninth valve 31.

Further, as shown in FIG. 5, after spraying the rust inhibitor solution, the rust inhibitor solution adhering to the dust collector 1 is dried to form a rust inhibitor film on the metal surface in the dust collector 1. if,
The rust prevention effect of the metal surface in the dust collector 1 can be maintained for a longer time.

As described above, after the ash adhering to the dust collecting plate 3 in the dust collector 1 is sufficiently removed, the dust collecting plate in the dust collector 1 is further removed.
By performing rust-preventive treatment on the metal surface such as 3, the discharge electrode 4, etc., it is possible to prevent the progress of corrosion inside the dust collector 1 for a long time after the plant is stopped. In addition, the completion time of the application of the washing water and the rust inhibitor can be grasped, and the application of the washing water and the rust inhibitor can be suppressed to the minimum amount, so that the running cost can be reduced.

[0020]

As described above in detail, according to the present invention, it is possible to provide a rust preventive treatment apparatus for a dust collector which can reliably and efficiently prevent corrosion inside the dust collector after the plant is stopped. it can.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a rust prevention treatment device for a dust collector according to the present embodiment.

FIG. 2 is an explanatory view of the dust collector of FIG. 1 as viewed from a side.

FIG. 3 is a sectional view taken along line XX of FIG. 2;

FIG. 4 is an enlarged sectional view showing a dust collecting plate and discharge electrodes in the dust collector of the present embodiment.

FIG. 5 is a characteristic diagram showing an example of a change in the pH value of the effluent from the inside of the dust collector according to the present embodiment.

[Explanation of symbols]

1 ... dust collector, 3 ... dust collecting plate, 4 ... discharge electrode, 5 ... spray nozzle, 6 ... supply source of cleaning water (industrial water), 10 ... tank, 11
... Rust inhibitor solution, 13 ... Rust inhibitor supply source, 25 ... Dust collector outlet, 28 ... pH meter.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Katsutoshi Yada 1-1-1 Wadazakicho, Hyogo-ku, Kobe-shi, Hyogo Mitsubishi Heavy Industries, Ltd. No. 1-1 in the Takasago Research Laboratory, Mitsubishi Heavy Industries, Ltd. (72) Inventor Yasumasa Ishibashi 2-1-1, Shinhama, Arai-machi, Takasago-shi, Hyogo Prefecture In the Takasago Research Laboratory, Mitsubishi Heavy Industries, Ltd. JP, A) JP-A-62-180765 (JP, A) JP-A-3-173338 (JP, A) JP-A-5-15811 (JP, A) JP-A-62-140953 (JP, U) (58) ) Surveyed field (Int.Cl. ⁶ , DB name) B03C 3/00-3/88

Claims (1)

(57) [Claims] 1. A spraying nozzle mounted in a dust collector, a washing water supply means for supplying washing water to the spraying nozzle, and measuring a pH value of a effluent from the dust collector. Anticorrosion treatment for a dust collector, comprising: a pH measuring device for supplying a rust inhibitor to the spray nozzle based on the pH value of the discharged liquid. apparatus.