JPS5851200B2 - How to clean combustion gas contact surfaces - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for quickly cleaning only a combustion gas contacting surface without harming other parts.

In general, deposits mainly composed of these fuel ash (hereinafter simply referred to as deposits) accumulate in various parts of boiler furnaces that burn heavy oil, crude oil, and residual oil from petroleum plants. It is known to induce various types of disorders.

(1) A large amount of deposits adheres to the outer surface of the heat transfer surface in the boiler furnace and obstructs heat transfer.

(2) As a result, the exhaust gas temperature rises, which adversely affects equipment in the gas flow path.

(3) Deposits are generally highly corrosive to metals and corrode heat transfer surfaces.

(4) When the amount of deposits increases, the exhaust gas flow path is narrowed, combustion itself becomes difficult, and normal operation of the boiler is inhibited.

On the other hand, the present inventors investigated the properties of deposits inside a heavy oil-fired boiler and obtained the results shown in the following table.

As is clear from the above table, even in the same boiler, the physical properties such as hardness and adhesion to heat transfer tubes vary depending on the location where it is deposited, as well as the chemical composition. However, at low temperatures, there is little vanadium and the pH of water-soluble components tends to be low.

In other words, the sulfur contained in the fuel reacts as follows: S+02→5O2 S +'/202→5O3 SO+HO4H2SO4 2 , and part of it becomes sulfuric acid. Sulfuric acid condenses more easily at lower temperatures, so the heat exchanger tube temperature Where the pH is low, the pH will be low.

Conventionally, in order to deal with the above-mentioned problems, deposits on the high-temperature pipes are removed using hammers, sandblasting, etc. when the tank is stopped, but this not only requires a lot of manpower but also creates noise and dust, which creates a difficult work environment. Moreover, in the latter case, problems remain when removing the used sand as waste, and the deposits on the low-temperature pipes are soft, and the heat transfer area is large, making it difficult to reach by human power. It cannot be removed by methods such as hot section tubes.

For this reason, it is possible to remove the deposits from the low-temperature pipes by washing them with water, but the pH of the washed water is low, and there are some parts where washing cannot be done sufficiently due to the structure, so the water that has been washed may stagnate. There is a risk of serious accidents such as progression of acid corrosion as a secondary failure.

To deal with this problem, it is possible to use alkaline water as washing water, but in addition to using alkaline water that is harmful to the human body, depending on the washing area, corrosion may occur due to insufficient acid neutralization, and when the ignition temperature rises. This is not a perfect countermeasure as it is affected by residual alkali salts.

Therefore, the present inventors investigated the properties of the deposits shown in the table above, and found that the water-soluble components are relatively difficult to remove, and if the washing water is modified, it is possible to remove the deposits while preventing acid corrosion. proposed a method of removing deposits while preventing corrosion by first covering parts that do not require water washing with a water-impermeable sheet and using washing water containing an acid corrosion inhibitor. No. 31558 [Unexamined Japanese Patent Publication No. 53-134102]
), is being applied to actual work, and through this work,
I realized that complete waterproofing of objects other than those to be washed is extremely important.

In other words, steel is generally used for the structural materials of heavy oil-fired boilers and combustion furnaces that heat steel materials, but refractory bricks are used for structural materials in areas where strength is unnecessary (i.e., areas other than the combustion gas contact surface). When the inside of the furnace is cleaned using the preceding method, it has a corrosion-preventing effect on steel materials, but since the firebricks are porous, the washing water is If a large amount of water permeates into the bricks and the temperature rises when the water is ignited after washing, the permeated washing water will evaporate and there will be no problem if the rising temperature is very slow, but under normal operation the washing water The evaporation of water is rapid, a large volumetric expansion occurs, and the destruction of the refractory brick occurs.

Therefore, it is necessary to prevent washing water from splashing on the refractory brick part (i.e., the part other than the combustion gas contact surface), and for this reason, in the above-mentioned previous method, waterproofing measures are taken using a non-water permeable sheet. However, it has been difficult to completely waterproof parts with complex structures.

The present invention has been made in view of the above points, and is a method for cleaning a combustion gas contact surface, which supplies water to a combustion gas contact surface on which deposits mainly composed of fuel ash have adhered to dissolve and remove the deposits. In the above, a method for cleaning a combustion gas contact surface is provided, which comprises applying an emulsion-like waterproofing agent made of synthetic resin to a portion other than the combustion gas contact surface to form a film, and then supplying water. It is something to do.

The waterproofing agent used in the method of the present invention is an emulsion obtained by dissolving a polymerizable monomer such as vinyl chloride monomer, acrylic monomer, vinyl acetate monomer, styrene monomer, or styrene-butadiene monomer in water using an emulsifier, or a hydrophilic polymer such as alkyd resin. and emulsions made from various synthetic resins that form a water-insoluble film once dried.As the emulsifier, anionic activators such as maleated polybutadiene can be used. .

The above waterproofing agent is applied to areas other than the combustion gas contact surface, but (1) it can be applied by spraying, brushing, or any other method, and (2) it can be diluted with water during application. (3) It can be applied to complex structures that cannot be reached by human power; (4) It forms an impermeable film after drying. Not only is the coating efficiency extremely high, but the waterproofing effect is also extremely good.

In addition, since the above waterproofing agent is composed of organic compounds such as C, H, and 0, even if the operation is restarted without removing the film after washing with water, the film will be burned, and the film will be burned. The waterproofing part has no negative effects at all.

Hereinafter, the gist of the method of the present invention, its operation, and effects will be explained using the accompanying drawings.

FIG. 1 shows an example in which the method of the present invention is applied to a boiler economizer.

In the figure, the distance between the economizer 1, which is the object to be washed, and the front, rear, left, and right side walls is narrow, about 50 mm, and after operation, this distance becomes even narrower due to deposits, and furthermore, the distance between the economizer 1 and the side walls, etc. Since various connecting pipes 2 and size mix ties 3 are provided between the economizer 1 and the economizer 1, it is impossible to completely cover the parts other than the economizer 1 with a non-water permeable sheet such as a vinyl sheet. In addition, water that has already been washed tends to accumulate.

Therefore, the above-mentioned waterproofing agent is diluted with water to an appropriate viscosity, and is allowed to flow down from each side wall of the upper part of the economizer 1 to the lower part using a spray, a brush, or the like.

Next, after confirming that the waterproofing agent is sufficiently applied to the intended application area using furnace lighting or a flashlight, the area is left to dry.

After drying, after confirming that there are no cracks or the like in the formed film 4, the waterproofing measures of the previous method may be applied using a water-impermeable sheet 5 such as a vinyl sheet to ensure complete safety.

Thereafter, washing water is sprayed by movable nozzles 6 installed at the upper and lower parts of the economizer 1.

The nozzle 6 is connected to a flow meter 8 by a flexible water supply pipe T.
It is connected to a water supply line 11 via a valve 9 and a water supply pump 10.

In addition, a hopper trust beam 12 is installed at the bottom of the economizer 1.
Scaffolding 13 is installed, and a receiving tank 19 for washing water is provided with a vinyl sheet or the like on top of the scaffolding 13. A drainage pump (slurry pump) 14 is attached to the bottom of the receiving tank 19.

The washing water sprayed from the movable nozzle 6 dissolves and peels off the deposits on the economizer 1 and falls into the receiving tank 19, but the parts other than the economizer 1 are covered with a film 4 and non-water permeable. Since the adhesive sheet 5 is completely waterproof, there is no possibility of any contact.

The washed water accumulated in the receiving tank 19 is transferred to the drain pump 1 described above.
4, and the flow rate and pH are checked through piping 15 through a flowmeter 17 and a pH meter 18, and the neutralization tank 1 outside the furnace is discharged.
Sent to 6.

The washing condition is determined based on the flow rate and pH tick, and the amount of washing water is increased or decreased depending on the situation.

As explained above, according to the method of the present invention, even in places where the structure is complex and human power cannot reach, waterproofing of parts other than the combustion gas contact surface is easy and complete, so that there is no possibility of harm to the parts. Only the combustion gas contact surface can be quickly cleaned without cleaning.

The method of the present invention is applicable not only to boilers but also to heating furnaces, garbage incinerators, gas turbines, etc.

Next, the effects of the method of the present invention will be explained in more detail with reference to Examples and Reference Examples.

Example A synthetic latex prepared by suspending an acrylic acid ester copolymer in water was used as a waterproofing agent, and it was applied as shown in FIG. 1 and left to dry for io hours.

In addition, the 5TBA24 gap test piece shown in Figure 2 (l21
0am, m=2018.1-1:3 Q. Using (1) and 5TBA24 flat plate test piece (5X20 X3 omm) (2), 1
), apply and dry the same waterproofing agent as above and apply it to the tank 19 directly below the economizer 1 (the position where the flushing water falls) and the water tank 19.
Tohe, regarding (2), apply the same waterproofing agent as above to one side and dry it, and put both into the receiving tank 19 without applying the waterproofing agent to the other side.
Installed each.

Thereafter, washing with water was performed as shown in FIG.

When we restarted the operation after washing, we found that the temperature of the exhaust gas from the economizer 1 had dropped by about 70°C compared to just before washing, and as a result, the deposits that had adhered to the economizer 1 were completely removed. It was found that heat recovery in the economizer 1 was carried out efficiently.

In addition, for the above test piece (1), approximately 40
After a period of time, the test piece was taken out, the film was removed, and the wet state of the gap was observed, but no moisture was observed.
As for 2), we took it out every hour and examined its corrosion weight loss, and found that those coated with waterproofing agent ranged from 0.005 to 0.
008■/cIfl-h, and those that were not coated were 0.
It was 1 to 0.157'Q〆bo・h.

Reference examples Waterproofing agent: (1) vinyl chloride monomer and emulsifier (maleated polybutadiene) dissolved in water to form an emulsion (2) acrylic monomer and the same emulsifier as (1) dissolved in water to form an emulsion (3) ) An alkyd resin made hydrophilic and emulsified with the same emulsifier as in (1) was applied to a commercially available refractory brick, and two days later, the refractory brick was immersed in water for 1 hour to determine its water content. , the results shown in the table below were obtained.

[Brief explanation of drawings]

FIG. 1 is an explanatory view showing an example of the case where the method of the present invention is applied to a boiler, and FIG. 2 is a perspective view showing a 5TBA24 gap test piece used in the example.

Claims (1)

[Claims] 1. In a method for cleaning a combustion gas contact surface in which water is supplied to a combustion gas contact surface to which deposits mainly composed of fuel ash have adhered to dissolve and remove the deposits, a synthetic resin is applied to a portion other than the combustion gas contact surface. A method for cleaning combustion gas contact surfaces, which comprises applying water to form a film by applying an emulsion-like waterproofing agent consisting of: