JP3396403B2 - Cleaning method of regenerative air preheater - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cleaning rotating elements of a regenerative air preheater used in coal-fired boiler equipment.

[0002]

BACKGROUND OF THE INVENTION Regenerative air preheaters are heat exchangers which transfer the high temperature heat of the exhaust gas of a boiler to the combustion air which is fed to the boiler via a rotating element which rotates horizontally on its vertical axis.
Therefore, the coal ash contained in the exhaust gas adheres and adheres to the rotating element having a radius of about 6 m through which the exhaust gas passes, particularly the intermediate temperature layer element. For this reason, as shown in FIG. 3, the housing 3 containing the rotary element 2 that horizontally rotates on the vertical axis 1 by a drive device (not shown) is connected to the upper inlet duct 4a into which exhaust gas flows through the denitration device. Inside and the outlet side duct 4 where the exhaust gas flows out
Cleaning pipes 5 and 6 for injecting cleaning water from above and below are arranged in the radial direction to the inside connected to b, and are provided in the exhaust gas inlet side damper D1 provided in the duct 4a and the duct 4b. The exhaust gas outlet side damper D2, the combustion air inlet side damper D3 provided in the duct 7a, and the combustion air outlet side damper D4 provided in the duct 7b are closed.
The industrial water supplied to the water tank 8 provided below the air preheater is pumped up by the pump P1, and the cleaning water is sprayed from above and below through the water supply pipe 9 from the cleaning pipes 5 and 6 to the rotating rotary element.
Coal ash and the like stuck to the rotating element are removed. The cleaning wastewater injected from the two cleaning pipes 5 and 6 to the rotary element rotates horizontally, and therefore the hopper 4'at the bottom of the outlet duct 4b below which exhaust gas flows out and the combustion air. Is supplied to the inside of the housing 3 and flows down to the hopper 7'at the bottom of the upward inlet duct 7a, and is discharged from both hoppers 4'and 7'into the water tank 8 through the drain pipe 10 and is circulated and used as washing water. Although not shown, a seal member is provided on the outer periphery of the rotary element 2 to seal the inner periphery of the housing 3 so that combustion air and exhaust gas are provided between the outer periphery of the rotary element and the inner periphery of the housing. To prevent it from flowing through.

[0003]

As described above, even if the washing pipes 5 and 6 are regularly washed with industrial water, the coal ash and the like cannot be completely removed. For this reason, coal ash or the like gradually accumulates in the rotary element over a long period of time, and the intermediate temperature layer element 2a of the rotary element is blocked, which may seriously hinder the operation of the boiler. Further, when hot water is sprayed on the rotating element as washing water, an acid such as sulfuric acid is generated and corrodes the rotating element.

[0004]

The present invention was developed in order to solve the above-mentioned problems, and a cleaning method according to claim 1 is for cleaning a rotary element of a regenerative air preheater with hot water. The acid corrosion inhibitor is added to the warm water without adding the acid neutralizer . Also, claim 2
The method of cleaning, see contains an acid corrosion inhibitor of the rotating element of the regenerative air preheater, after washing with hot water containing no antacid, washed with high-pressure jet water containing rust inhibitor, and rust It is characterized by performing.

[0005]

EXAMPLE FIG. 1 (A) shows that the medium temperature layer element of the rotary element is blocked to some extent, and the differential pressure of the air preheater tends to rise, so that a chemical tank, a chemical pump, a high-pressure washer mounted on the vehicle, etc. Of the temporary equipment is carried in, the rotary element is washed with hot water by the nozzle header 12, and then high pressure water from the high pressure jet pump built in the high pressure washing machine 21 mounted on the vehicle is washed by the high pressure jet water jetted from the automatic washing nozzle 22. Indicates the state to be performed.

Even when the above cleaning is performed, the dampers D1
, D2, D3, D4 are closed. During hot water cleaning and high pressure jet water cleaning, steam mist is generated to protect the denitration catalyst and prevent boiler corrosion in the furnace.
The manhole cover on the housing 3 and the ducts 7a and 7b is opened, and the worker enters the manhole through the manhole, and the side of the dampers D1, D2, D3, and D4 facing the inside of the housing 3 is sealed with a flameproof sheet 11. And seal. Specifically, stains (coal ash, rust, etc.) on the inner wall surface of the duct to which the flameproof sheet 11 is attached are removed, a double-sided adhesive tape is attached, and the peripheral edge of the flameproof sheet 11 is attached to the double-sided adhesive tape. Urethane foam is sprayed and sealed at the boundary between the peripheral edge portion and the inner peripheral wall surface of the flameproof sheet to a thickness of 30 to 50 mm and a width of 150 to 200 mm.

First, the washing with hot water will be described. The carried-in nozzle header 12 is a main pipe 13 which is radially inserted into the housing as shown in FIG. 1B, and a predetermined space (for example, 1 m) from the main pipe. ) And a plurality of branch pipes 14 connected in an orthogonal manner, the length of the branch pipes 14 located on the outer peripheral side of the rotary element is long, and a large number of nozzles 15 are attached downward and positioned on the inner peripheral side. The rod lamp shape has a shorter length and a smaller number of downwardly mounted nozzles 15. In the figure, the length of the two branch pipes 14 on the outer peripheral side is 3 m, and four nozzles are attached at equal intervals. The length of the two branch pipes inside is 2 m, and three nozzles are equally spaced. The length of the two branch pipes on the inner peripheral side is 1 m, and nozzles are attached to both ends.

Each branch pipe 14 is composed of two pipes 14a, 14b of the same length which can be attached to and detached from the main pipe 13 in the shape of a cross. In order to arrange the nozzle header 12 so as not to interfere with the cleaning pipe 5 in the housing 3, the main pipe 13 is inserted in the radial direction from the manhole, and the operator holds two branch pipes from each of the branch pipes to move the housing from the manhole. 2 of each branch pipe to the main pipe 13 that is inserted from the manhole in the radial direction.
Assemble the books by attaching them to the cross. Then, the base portion 13 'of the main pipe projecting outward from the manhole is connected to the water supply pipe 9, and the nozzle header 12 is suspended from the housing or welded to the housing to be supported.

In order to inject hot water from the nozzle 15 of the nozzle header to the rotary element, an in-line heater 16 into which steam is injected is connected in the middle of the water supply pipe 9. Further, by injecting the industrial water and acid corrosion inhibitors without the addition of acid neutralizing agent in chemical tank 17 carried, the amount of the acid corrosion inhibitor industrial water in the water tank 8 by chemical feed pump P2 0.
It is added so as to be 0 to 1%, preferably 0.03 to 0.05%. As this acid corrosion inhibitor, a liquid anti-rust (registered trademark) J manufactured by Kurita Engineering Co., Ltd. is used.
-10 can be used. 18 is a chemical tank 17
The piping for injecting industrial water is shown in.

[0010] performing warm water washing, the nozzle header manhole inserting the main 13 of or aゝopen, closing valve of the existing washing pipe 5,6, in water bath 8 in which the acid corrosion inhibitor was added Of industrial water is pumped up to the water supply pipe 9 by the pump P1, heated to about 50 to 70 ° C. with steam supplied to the in-line heater 16 connected in the middle of the water supply pipe, and the nozzle header 12
It is jetted from the nozzle 15 to the rotating element 2. The rotation speed of the rotary element is appropriately adjusted by a drive device (not shown). Since the cleaning water drained from the hoppers 4'and 7'through the drain pipe 10 to the water tank 8 contains the acid corrosion inhibitor, it can be circulated and used for 20 to 26 hours. After the first washing with warm water, the washing is interrupted, the water in the water tank 8 is discharged, new industrial water and an acid corrosion inhibitor are added without adding an acid neutralizing agent , and the washing is performed again for 20 to 26 hours. Circulate water to wash with warm water. 2-3 times to wash with warm water
It's enough. Since the cleaning water contains an acid corrosion inhibitor, it can be circulated and used for 20 to 26 hours.
Use less wash water.

When the rotating element is washed with warm water to remove the coal ash that adheres and accumulates, the sulfuric acid contained in the coal ash turns the washing water into sulfuric acid acid water, and this sulfuric acid water is removed after removing the coal ash and the like. Although the surface of the steel material of the rotating element is corroded, since the acid corrosion inhibitor is added to the cleaning water, the rotating element is not corroded after cleaning.

After the washing with warm water was completed, a worker entered the housing from the manhole and connected to the left and right sides of the main pipe.
Remove the branch pipe for the book and take it out of the housing.
Is pulled out from the manhole and the in-line heater 18 connected to the water supply pipe 9 is removed.

Next, cleaning with high-pressure jet water will be described with reference to FIG. The automatic cleaning nozzle 2 in which the manhole cover at the upper part of the housing near the duct 7b for flowing the heated combustion air toward the boiler is opened, and the worker enters and is carried in
An I-beam 23 as a rail for movably mounting 2 is inserted radially inside the housing above the rotating element. The vertical axis 1 of the rotary element has an outer cylinder 1a that rotates integrally to fix the rotary element 2, and a non-rotating slip ring 1'is provided on the outer cylinder, so The end is this slip ring 1 '
It is placed on top and the outer end is welded and fixed to the housing 3. Then, the automatic cleaning nozzle 22 is attached to the I-beam, and a bearing device supporting the sprockets 24 is attached to the inner and outer ends of the I-beam to automatically clean the endless chain 25 stretched between the sprockets 24, 24. The sprocket 24 on the outer end side is connected to the nozzle 22 and is driven to rotate forward and backward by an air motor so that the automatic cleaning nozzle can reciprocate along the I-beam.

An industrial water pipe 18 and a pipe from the above-mentioned chemical injection pump P2 are connected to a tank 26 of a vehicle-mounted high-pressure washing machine, and the tank 26 and an automatic washing nozzle 22 are connected by a high-pressure hose 27. Since the automatic cleaning nozzle 22 reciprocates along the I-beam, the length of the high pressure hose is determined so that the automatic cleaning nozzle does not interfere with the reciprocating motion.

To carry out cleaning with high-pressure jet water, I
The manhole to which the beam 23 is attached remains open, and a rust preventive agent and industrial water from the pipe 18 are poured into the chemical tank 17. As the rust preventive agent, liquid anti-laser (registered trademark) J-4 manufactured by Kurita Engineering Co., Ltd. can be used. Pipe 1 for industrial water to the tank 26 of the high-pressure washer
The water is continuously supplied from 8 and the rust preventive agent in the chemical tank 17 is continuously proportionally injected into the tank 26 from the chemical injection pump P2 so as to be 0.3 to 0.5%, and the high pressure jet pump of the high pressure washing machine is used. The cleaning water containing the rust preventive agent is supplied to the automatic cleaning nozzle 22 via the high pressure hose 27, and jetted to the rotating element.

At this time, the rotation of the rotary element is appropriately adjusted by a driving device (not shown), and the jet pressure is 200 to 3
50 kg / cm ² , the amount of washing water is 20 to 40 m ³ / hour, the automatic washing nozzle 21 is positioned on the inner circumference of the rotating element, and the automatic washing nozzle is directed to the nozzle width (90 mm) every time the rotating element makes one rotation. Although it is moved intermittently toward the outer periphery, in a place where the blockage is severely blocked, the automatic cleaning nozzle is stopped and intensive cleaning is performed during multiple rotations of the rotating element, thus taking about 20 hours from the inner periphery to the outer periphery of the rotating element. Wash all around until. Since the cleaning water sprayed on the rotary element is discharged from the hoppers 4'and 7'through the drain pipe 10 to the water tank 8, it is continuously discharged from the water tank 8 during cleaning.

Since the high-pressure jet water contains a rust preventive agent, even if the metal surface of the rotating element is exposed by cleaning, the rust preventive agent prevents secondary rusting. It never happens.

By sufficiently performing the warm water cleaning performed by circulating the cleaning water in the preceding stage, the cleaning time with the high pressure jet water can be shortened and the amount of the high pressure jet water used can be reduced.

After the washing with the high-pressure jet water, the worker enters the inside of the housing through the manhole, removes the automatic washing machine and the sprocket bearing device from the I-beam, removes the high-pressure hose from the automatic washing machine, and takes them out respectively. Then remove the I-beam from the housing and pull it out of the manhole. And these, a chemical tank, a chemical pump,
Remove temporary equipment such as the nozzle head.

Finally, a worker enters from the manhole, removes the flameproof sheet 11 with the seal curing on the side facing the inside of the housing of each of the dampers D1, D2, D3, D4, and puts it out, and puts a lid on each manhole. Install and close, open each damper and restart operation.

[0021]

As is apparent from the above, according to claim 1 of the present invention, when the rotating element of the regenerative air preheater is washed with warm water, the acid corrosion inhibitor is added to the warm water without adding an acid neutralizing agent. Therefore, the deposits such as coal ash that cannot be removed by washing with normal temperature water are added with warm water containing an acid corrosion inhibitor.
Together can be removed and dissolve, the corrosion of metal parts of the rotating element with sulfuric acid water produced during the washing can be suppressed with an acid corrosion inhibitor, and can use the washing water long circulating, washed The amount of water used can be reduced.
In addition to the effect of claim 1, in the second aspect, since the metal portion of the rotating element is subjected to the rust prevention treatment at the time of washing with the high pressure jet water, it is possible to prevent rusting after washing.

[Brief description of drawings]

FIG. 1A is an explanatory view showing a state where hot water washing and washing with high-pressure jet water are prepared, and hot water washing is performed;
(B) is a perspective view of a hot water washing nozzle header.

FIG. 2 is an explanatory diagram showing a state where cleaning is performed with high-pressure jet water.

FIG. 3 is an explanatory view showing the operation of the regenerative air preheater.

[Explanation of symbols]

1 Vertical axis of regenerative air preheater 2 Rotating element of regenerative air preheater 3 Regenerative air preheater housing 4a Exhaust gas inlet side duct 4b Exhaust gas exhaust side duct 4'hopper 5 Washing pipe 6 washing pipe 7a Combustion air inlet side duct 7b Combustion air outlet side duct 7'hopper 8 aquarium 9 Water supply pipe to the washing pipe Drainage pipe to 10 water tank 11 Flameproof sheet 12 Nozzle header for hot water cleaning 13 Main of nozzle header for washing with hot water 14 Branch pipe of nozzle header for washing with warm water 15 Hot water cleaning nozzle Header nozzle 16 In-line heater 17 Chemical tank 18 Industrial water supply pipe 21 High pressure washer 22 Automatic cleaning nozzle 23 I-beam 24 sprockets 25 endless chain 26 High Pressure Washer Tank 27 high pressure hose

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-9-126689 (JP, A) SAIKAI 62-70291 (JP, U) SUNKOKEI 2-33040 (JP, Y2) JPB 57- 13794 (JP, B1) (58) Fields surveyed (Int.Cl. ⁷ , DB name) F28G 9/00 F28G 1/16

Claims (2)

(57) [Claims] 1. When washing the rotating element of a regenerative air preheater with warm water, an acid neutralizer is not added to the warm water.
A method for cleaning a regenerative air preheater, which comprises adding a oxalic corrosion inhibitor. 2. A viewing including the acid corrosion inhibitor of the rotating element of the regenerative air preheater, after washing with hot water containing no antacid, washed with high-pressure jet water containing rust inhibitor, and rust A method for cleaning a regenerative air preheater, which comprises: