JP2008082628A - Chimney stack maintenance method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for removing a brittle portion of an existing inorganic lining material and then applying to the surface an epoxy resin as a surface protecting material having sulfur permeating resistance, fluorine permeating resistance and high heat resistance to elongate the life of a chimney stack. <P>SOLUTION: The maintenance method is provided for the chimney stack 10 formed by applying the inorganic lining material 12 such as mortar or bricks to the inner face of a steel cylindrical body 11. It comprises removing or separating the brittle portion 13 on the lining surface with blasting or high pressure water washing, and then applying the heat resistant epoxy resin to the surface to form a surface protecting layer 15. The epoxy resin is applied thereto in two or three times to be 100-3,000 μm, preferably, 300-1,000 μm thick. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a maintenance method of a metal chimney such as steel used in, for example, an electric power company, an oil complex and an incinerator chimney, and more specifically, an inorganic lining surface applied to the inner surface of a cylinder body, The present invention relates to a chimney maintenance method for extending the life of a chimney by applying an epoxy resin composition having sulfur permeation resistance, fluorine permeation resistance, and high heat resistance.

  Conventionally, steel chimneys used in electric power companies, petroleum complexes, incinerator chimneys, etc. are sprayed with mortar on the inner surface of the cylinder or bricks or anti-fluorite blocks to prevent corrosion. An inorganic lining material is applied.

  As a known chimney, for example, as shown in FIG. 3, a stud bolt 21 is fixed to the inner surface of a steel cylinder 20 at a predetermined interval, and a vertical bar 22 and a horizontal bar are connected to the stud bolt 21. 23 and a metal mesh 24 are attached, and a structure in which an inorganic lining material 25 made of mortar is sprayed to a predetermined thickness on the inner surface of a cylindrical body 20 using these as a reinforcing core material is known.

Further, as shown in FIG. 4, an inorganic running material 25 made of brick or anti-fluorite block having a predetermined thickness is pasted on the cylinder body 20 using a back joint material 26 and a joint material 27 extending vertically and horizontally as adhesives. The structure is also known.
Japanese Patent Laid-Open No. 10-184034 Japanese Patent Application Laid-Open No. 11-141853

  However, when the above-described inorganic lining material 25 has been used for more than 10 years, the lining material in the weakened region is weakened due to deterioration caused by sulfur and fluorine in the smoke passing through the chimney. There is a problem that it peels off and scatters with the smoke outside the chimney, causing pollution problems.

In addition, cracks and cracks are generated in the weakened region, and there is a possibility that sulfur or fluorine penetrates not only the reinforcing core material but also penetrates the steel plate constituting the tubular body and corrodes them. In particular, dozens of types of raw coal are used in coal-fired power plants, and the composition of the exhaust gas changes frequently. Therefore, the deterioration of the lining material due to sulfur and fluorine in the exhaust gas becomes more remarkable.
In order to deal with such problems, conventionally, there is a method in which an existing inorganic lining material is suspended by using a wheel cutter, an air breaker, etc., and a new inorganic lining material is replaced at the site to perform necessary maintenance. It has been adopted.

Further, for example, in the case of a chimney of a power plant, since a regular operator inspection (regular inspection) is usually performed every two years, it is preferable to complete the replacement work of the lining material during this period. However, the periodic operator inspection must be completed in two months, during which the lining material is replaced, that is, the existing lining material is suspended, the damaged reinforcing core material is replaced, and the lining material is blown. Each process, such as attaching or pasting, curing the lining material, takes time, and the chimney length is about 30 to 35 m (about 500 m ² ) within a very small height within the regular inspection period of about 2 months. The lining material cannot be updated.

  For this reason, when the existing lining material is replaced using the regular inspection period, for example, if the chimney is 200 m, the entire lining material cannot be replaced within the service life of the lining material. Therefore, providing a chimney repair period other than the regular inspection period is undesirable for the operation of the power plant and the like, and therefore an improvement method is desired.

By the way, in order to improve the said problem, patent document 1 removes only the surface side of a lining material, and applies the inorganic lining material to the said surface side instead of replacing | exchanging the existing lining material completely. Maintenance methods and devices for repair have been proposed.
However, since it takes a considerable amount of time for the newly established lining material to fully cure and exhibit the same physical properties as the existing lining material, the maintenance of the existing lining material and the newly installed lining material for several months after the maintenance is completed. The strengths are different, which causes the interface peeling.
Further, Patent Document 2 proposes a method of relining the lining function by lining the surface with a corrosion-resistant steel plate while leaving the existing lining material, but enormous costs are required because the entire surface is covered with the corrosion-resistant steel plate. There is an inconvenience.

[Object of invention]
The present invention has been devised by paying attention to such inconveniences, and its purpose is to remove the fragile portion of the existing inorganic lining material and to prevent sulfur permeation resistance and fluorine permeation resistance as a protective agent on the surface thereof. It is an object of the present invention to provide a chimney maintenance method capable of extending the life of a lining material, and thus a chimney, by applying an epoxy resin having heat resistance and high heat resistance.

In order to solve the above-mentioned object, the chimney maintenance method according to the present invention is a chimney in which an inorganic lining is applied to the inner surface of a metal cylinder,
After removing the weak part of the lining surface, an epoxy resin is applied to the surface to form a surface protective layer.

  In the maintenance, a method is adopted in which the fragile portion is removed or peeled off by blasting or high-pressure water washing (for example, 100 to 300 MPa), and the fragile portion is dried, and then the epoxy resin is applied. The fragile portion is cleaned by uniformly removing the surface side of the lining material to a depth of 3 to 5 mm.

  Moreover, the said epoxy resin is good to apply | coat to 2-3 times so that it may become a film thickness of about 100-3000 micrometers by spray application, Preferably, it is about 300-1000 micrometers.

In the present invention, as shown in FIG. 1A, an inorganic lining material 12 such as mortar or brick is provided on the inner surface side of a cylinder 11 of a chimney 10 via a reinforcing core material or an adhesive (not shown). Applicable to chimneys.
When fragile portions 13A and 13B deteriorated by long-term use occur on the surface side of the lining material 12, initial work is performed to remove or peel the fragile portions 13A and 13B to expose a healthy surface. At this time, since the fragile portion 13A is shallow, the fragile portion removal region 14A (see FIG. 1B) can be obtained simply by removing or peeling. On the other hand, since the fragile portion 13B has a large cross-sectional defect, it is preferably backfilled with a similar lining material (see A portion in FIG. 1B) to form the fragile portion repair region 14B.
Then, after the fragile portion removing area 14 </ b> A and the fragile portion repairing area 14 </ b> B are sufficiently dried, the epoxy resin is spray-coated on the surface of the lining material 12 as the surface protective layer 15. This spray application is performed on the entire surface of the lining material 12 including the fragile portion removal region 14A and the fragile portion repair region 14B, but it does not prevent the surface of the fragile portion removal region 14A and the fragile portion repair region 14B from being made only.

According to the maintenance method of the present invention, sulfur permeation resistance / fluorine permeation resistance is maintained for a long time in high-temperature exhaust gas at 120 to 140 ° C., and the sulfuric acid content (SO ₂ to the inorganic lining material) is maintained.
, SO ₃ ) · hydrofluoric acid (HF) can be prevented.

The epoxy resin composition constituting the surface protective layer 15 of the present invention has a viscosity of 0.3 to 30 Pa · s and has sulfur permeability resistance and fluorine penetration resistance even at high temperatures. The epoxy resin used here has a structure having a bisphenol skeleton, a phenol novolac skeleton, or a glycidylamine skeleton and having a glycidyl group at the terminal or side chain.
The diluent is a glycidyl ether type epoxy resin.
The filler can contain finely divided silica, and the other additive can contain a dibutyltin compound as a catalyst.
As the curing agent, 4.4-diaminodiphenylmethane, 1.3-phenylenediamine,
It is a mixture composed of N- (3-phenoxy-2-hydroxypropyl) -m-phenylenediamine, 4- (3-phenoxy-2-hydroxypropylamine) -4-diaminodiphenylmethane, and other modified aromatic polyamines.

According to the present invention, the surface protective layer has sulfur permeation resistance, fluorine permeation resistance, and high heat resistance, has high adhesion to the lining material, and can exhibit long-term stable durability. By applying an epoxy resin that forms such a surface protective layer, the penetration of sulfur into the future inorganic lining can be greatly reduced, and the life of the lining material can be expected to be greatly extended. Cost can be greatly reduced.
Further, by forming the surface protective layer on the inner surface of the lining material, it is possible to reduce the deterioration of the surface of the lining material and to eliminate the scattering pollution of the peeled material and dust.

As an evaluation test, the following composition was used as a material for the surface protective layer.
Three Longji M-702 is a heat resistant epoxy resin manufactured by Three Bond Unicom.
Three Longji AX-006 is a fast-curing acrylic adhesive manufactured by Three Bond Unicom.
Ceraprotex C2031 is a modified silicone-based heat-resistant and anticorrosive material having a terminal glycidyl group manufactured by Nikkei Co., Ltd.
Pyrokeep TS-1300 is a heat-resistant specially modified silicone resin manufactured by Otsuka Chemical Co., Ltd.

[Evaluation test] Evaluation of heat resistance and chemical resistance Various materials for forming a surface protective layer were applied to an inorganic lining material (Portland cement cured product) of 40 x 40 x 160 mm, and (23 ° C x 24 hours) + ( A specimen cured and cured at 80 ° C. × 3 hours + (150 ° C. × 3 hours) was used as a test piece. A chemical (1% sulfuric acid, 1% hydrofluoric acid) was poured into a pressure vessel so that about 1/3 of the test piece was immersed, and a heat cycle test according to the steps shown in FIG. 2 was performed.
The results of the evaluation test are shown in Table 1 below.

[Example]
Examples of the present invention will be specifically described below.
Epoxy resins were prepared to sprayable viscosities at the compounding amounts of Example 1 and Example 2 using the compounds shown in Table 2 below. Moreover, the said three-longie M-702 was used.

Using the chimney B of an actual coal-fired power plant, the surface of the inorganic lining material is washed with ultra-high pressure water, and the fragile portion of the surface is uniformly removed by 3 to 5 mm to expose a healthy surface of the inorganic lining material. It was. After sufficiently drying, Three Longji M-702 was applied with a rubber spatula, and Examples 1 and 2 were applied by airless spraying. (Two coats, average film thickness 700μm)
After that, when the boiler stopped, it entered the chimney and checked over time (visual appearance, sulfur penetration depth measurement, fluorine penetration depth measurement, Kenken-type adhesion test). The results are shown in Tables 3 to 6 below. In addition, each measurement of sulfur penetration depth and fluorine penetration depth is measured by energy-dispersive X-ray spectroscopy by collecting the core of the surface protective layer in the chimney. That is, characteristic X-rays generated from a sample are directly detected by a semiconductor detector, converted into an electric signal, and subjected to spectral analysis.

As is apparent from Table 3, since each composition used an aromatic polyamine as the curing agent, it turned black, but the gloss was not lost, and no floating, cracking, peeling, or the like was observed.
Further, as shown in Table 4, the sulfur penetration depth is stable for each composition, and there is no penetration diffusion of sulfur into the underlying inorganic lining. In addition, although there exists a part in which sulfur penetration depth has decreased with progress of days, this is considered to originate in having a different measurement point. However, in general, the sulfur penetration depth is not significantly increased.
Further, as shown in Table 5, no fluorine permeation was observed in each composition, and there was no permeation diffusion of fluorine into the underlying inorganic lining. Here, the fluorine permeation is zero because the fluorine content contained in the combustion gas of coal used during the evaluation period is very small. (However, some types of coal contain a large amount of fluorine component, which is a cause of deterioration of the inorganic lining, so the fluorine penetration resistance was also evaluated.)
Further, as apparent from Table 6, the adhesion of the protective material of each composition was measured using a Kenken-type adhesive strength tester, but there was no problem with the adhesion due to the destruction of the base material from the base.

[Comparative Example 1]
The above four types were applied as surface protective materials for the inorganic lining to the two types of chimneys A and B burning different fuels from the coal-fired power plant in operation, and the progress was observed. The results are shown in Table 7.

  As is apparent from Table 7, when the surface protective material according to the present invention was applied to the lining surface using an epoxy resin, no abnormality in appearance was observed with respect to the composition of the comparative example, and sulfur. It is clear that the penetration depth can be suppressed.

(A) is a partial schematic cross-sectional view of a chimney to which the method of the present invention is applied, and (B) is a partial schematic cross-sectional view showing a state at the end of maintenance. The flowchart of the heat cycle test which evaluates the heat resistance and chemical resistance of this invention. The partial cross section figure which shows the conventional chimney structure. The partial cross section figure which shows the other conventional chimney structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Chimney 11 Cylinder 12 Inorganic lining material 13 Fragile part 16 Surface protective layer (epoxy resin)

Claims (3)

In the chimney maintenance method with an inorganic lining on the inner surface of a metal cylinder,
A chimney maintenance method comprising removing a fragile portion of the lining surface and then applying an epoxy resin to the surface to form a surface protective layer. The chimney maintenance method according to claim 1, wherein the fragile portion is peeled off by blasting or high-pressure water washing, and the fragile portion is dried, and then the epoxy resin is applied. The chimney maintenance method according to claim 1, wherein the epoxy resin has a coating thickness of 100 to 3000 μm by spray coating.

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