JPS62242713A - Flow regulator plate for coal burner nozzle - Google Patents

Abstract

PURPOSE:To improve an anti-wear characteristic and a heat-resistant shock characteristic by a method wherein a main body of flow regulator removably inserted into main bodies of a plurality of stage nozzles is formed by a chromeum-nickel steel and a ceramics is attached to a surface part of the flow regulator plate with a fixing member of chromeum-nickel-molybdenum steel. CONSTITUTION:As a material of a main body 3 of flow regulator plate, a chromeum- nickel steel containing more than 23% of chromeum is used in consideration of an anti-oxidation characteristic, a hot temperature strength and a thermal shock characteristic. A rectangular plate-like ceramics 4 is attached to a rear part 3b of the flow regulator plate showing an excessive wear due to fine powder coal. A fixing of the fixing member 11 to the main body 3 of the flow regulator is performed by a stud welding method which is used in a general metallic material welding process. The fixing member 11 is made of chromeum-nickel-molybdenum steel and so a clearance machining with the ceramic fixing hole under a mechanical work before an aging hardening in a hot temperature heating operation can be performed. Since the main body of the flow regulator plate can be extended, its crack can be prevented and further an excessive hard ceramics is fixed with the fixing member to a surface of the rear part showing erosion, so that it is possible to improve an anti-wear characteristic.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement of a rectifier plate for a coal burner nozzle of a combustion device for a coal-fired boiler used in a high-temperature, heavily worn part.

[Conventional technology]

FIG. 4 shows a general coal burner nozzle, and FIG. 5 shows a conventional rectifier plate for a coal burner nozzle.

This coal burner nozzle has a stainless steel nozzle body 01
A plurality of grooves 02t are formed in the groove 02t, into which a rectifying plate 03f made of high Or cast iron or chromium-nickel steel is removably inserted. With this coal burner nozzle,
Pulverized coal pulverized by the mill passes through the upper or lower part of the rectifying plate 05 from a pulverized coal supply pipe (not shown) connected to the nozzle body 01, and is blown into the furnace and burned.

That is, pulverized coal flows in the direction of arrow A (upstream) to arrow B (downstream). Therefore, as shown in FIG. 5, the temperature of the front part 03& of the rectifying plate 03 near the furnace is 10% due to the combustion flame of the furnace.
The temperature rises to nearly 00C. Further, since the pulverized coal becomes a high-speed powder slurry and flows toward the current plate 03, erosion occurs at the rear part n5b (shaded area) of the current plate 05 due to collision of the pulverized coal.

Therefore, if the entire baffle plate 03 is made of a single plate and made of high wear-resistant cast iron, the material has almost no ductility and the temperature difference between the front part Q5a and the rear part 03b of the baffle plate 03 increases. Thermal stress is generated, and this thermal stress causes cracks C to occur from the poona portion Q3a of the baffle plate 05, causing fragments to fall to the bottom of the furnace, damaging the tube metal, and causing problems such as deterioration of combustion efficiency.

Furthermore, if the entire current plate 03 is made of a single plate made of chromium-nickel steel, etc., the erosion resistance is inferior to that of the above-mentioned high ar cast iron.

Therefore, the degree of wear due to erosion by pulverized coal is greater than that of high-Or cast iron, and its life is significantly shorter than that of high-Or cast iron.

Further, the wear resistance may be improved by attaching ceramic gold, which has high hardness and excellent wear resistance, to the rear part of the rectifier plate 05 where the p-john occurs. However, since ceramics have almost no ductility, the current plate 0
3.Using a single ceramic plate at the rear is highly effective.
Same as cast iron plate, it is impossible.

Therefore, it is practical to make the main body of the current plate 03 from a metal material and use ceramics only on the surface of the rear part 03b of the current plate where erosion occurs. However, it is extremely difficult to attach ceramics to metal, and methods such as bonding with inorganic adhesives, brazing with special alloys, mechanical fixation with metal bolts, and welding with metal material pins are generally used. .

The rectangular plate-shaped ceramic 04 is attached to the rear ASB of the rectifier plate using an inorganic adhesive.
Since the operating temperature of the rear part 03kl of the rectifier plate reaches approximately 700C, the ceramic 04 may crack due to thermal changes in the adhesive.

The details are shown in FIG. 7, and cracks 06 occur due to shrinkage of the adhesive 05. In addition, there is no suitable brazing material for bonding using a brazing filler metal because the temperature at which it is used is high, and bonding between metal and ceramic 04 using a brazing filler metal has a problem in terms of adhesive strength.

[As shown in FIG. 8, when the ceramics 04 and the rectifying plate main body 05 are fixed by the metal bolts 07, the ends of the metal bolts 07 are exposed on the surface of the rectifying plate 05, so the two lotions caused by the coal powder are intense. In extreme cases, the ceramics 04 may fall off from the current plate body.

Furthermore, as shown in Figure 49, the metal material pin 08 is joined to the ceramic 04 and the rectifying plate body 03 by welding, but even in this method, since the metal material pin 08i is exposed on the surface of the rectifying plate 03, it is subject to erosion, and in severe cases. This may cause ceramics 04 to fall off. Generally, the metal material pin 08 and the current plate 03 can be joined by stud welding. 09 in FIG. 9 is the stud welding portion.

Furthermore, as shown in FIG.
4' may be considered, but in the case of the rectifier plate O5 used at high temperatures, it is difficult to join the ceramic cover 04' and the metal material pin 08.

Bonding metal materials and ceramics using metal pins is a common method and is considered to be a reliable method at present. When joining metal and ceramics using metal material pins, the coefficient of linear expansion of ceramics is lower than that of metals. Required between the hole and the metal pin. Finally, in order to prevent cracking of the ceramic due to the difference in thermal expansion, a metal pin is prepared to form a gap with the ceramic, but it is necessary to process and form a mounting hole on the ceramic side. Mounting holes in ceramics are hard after firing, so it is common practice to machine them before firing, but forming gaps is done by machining metal pins, which are easier to machine than precisely machining mounting holes in ceramics before firing. is common.

Materials with excellent wear resistance such as 7t, ceramics, and high CR cast iron have high hardness and are difficult to machine, so metal pins are machined as described above, and in this case, materials with low hardness that are easy to machine are used. Since the metal pin used as the mounting material does not have sufficient wear resistance.

The metal pins that are commonly used as mounting materials have a chromium content of less than 20X, so they lack oxidation resistance, and there is a concern that the metal pins that are the mounting materials will be worn out by oxidation and the ceramics will fall off.

[Purpose of the invention]

The present invention has been made in order to eliminate the above-mentioned drawbacks, and its purpose is to provide a current plate for a ceramic-mounted coal burner nozzle that has excellent wear resistance and high thermal shock resistance that does not cause cracking during use. It is something.

[Means for solving problems]

The present invention includes a rectifying plate main body that is removably inserted into a multi-stage nozzle body, and is made of chromium-nickel steel, and a mounting material of chromium-nickel-molybdenum steel is used on the surface of the rectifying plate, which is subject to severe wear. This is a rectifier plate for tip-attached coal burner nozzles.

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

FIG. 1 shows a rectifier plate for a coal burner nozzle according to one embodiment of the present invention.
Since the oxidation resistance can reach up to 1OOOC, a material with good high-temperature oxidation resistance is required. Further, the rear part 5b of the baffle plate is cooled by the air carrying the fine powder and subjected to C thermal shock, so it requires full ductility.

When the chromium content of chromium-nickel steel increases to 23x or more, the oxidation resistance in air up to 1200 t:' is significantly improved. Therefore, in the present invention, the material of the current plate main body 5 is 25 Or -20Ni containing 25x or more chromium, taking into account oxidation resistance, high temperature strength, and thermal shock properties.
450r -50Ni, 5 Q Or -50N1
Use chromium-nickel steel such as

A rectangular ceramic plate 4 is attached to the rear part 5b of the rectifier plate, which is subject to severe wear due to pulverized coal. Ceramic 4Fi alumina, silicon carbide, silicon nitride, zircon, etc. may be used, but alumina is usually used because it is cheap.

The installation of the current plate 3 and the ceramics 4 will be explained with reference to FIG. Reference numeral 5 denotes a main body of the rectifying plate, 4 a ceramic material with mounting holes formed in advance, 11 a metal material for mounting, and 12 a gap in consideration of thermal expansion of the mounting material at the operating temperature of the rectifying plate. This gap 12 is usually determined by the thermal expansion coefficient ax1o-'/C (0 to 8 Q QC) of ceramics (in the case of alumina).
The difference between the thermal expansion coefficient 19xto-'/C (ri~aooc) of the mounting material (chromium nickel molybdenum steel) and the mounting material (chromium nickel molybdenum steel) is 11X
O-'/C: Determined by considering the operating temperature of 700C and the diameter of the mounting hole.

The mounting hole may be of any shape, but it is preferably in the shape of an inverted truncated cone, as shown in the figure, to prevent the ceramic from falling off.

The mounting material 11Ω can be fixed to the rectifying plate main body 3 by stud welding, which is commonly used for welding metal materials. 9 is the stud welded part. The mounting material 11 is chrome, nickel,
It is a molybdenum-based steel, and its hardness is as low as 250 Brinell hardness before age hardening by high-temperature heating, making it possible to machine the gap between it and the ceramic mounting hole.

However, with this hardness, as shown in FIG. 3, the erosion resistance is lower than that of ceramics, so there is a risk that the mounting portion will wear out and the ceramics will fall off. The test results shown in Fig. 3 are based on the current plate main body S (450r-50Ni
Cast steel), Ceramics 4 (Alumina), Mounting materials 110 Materials before and after age hardening and high cr cast iron for reference (0; 2.75.81 g G, 57, Mn;
0.64, Or; 25.50. An erosion test was conducted on the remaining Fa) in pulverized coal ash. The test conditions were a flow rate of 100 m/see, an ash impact angle of 90 degrees, an ash concentration of 50 jl/ml', and a test time of 8.
It is 0 hours.

The amount of wear was measured by measuring the depth of wear with a surface roughness meter, and then expressed as a comparison with a standard material (carbon steel) tested at the same time.

From Figure 3, it is clear that the ceramic (alumina) attached to the rear of the rectifier plate has excellent wear resistance, and is about 6 times more resistant to wear than the rectifier plate itself.

Gap processing and stud welding are performed with the mounting material having low hardness.This is because when welding materials with high hardness, the welded part is likely to break during welding.

After welding the mounting material to the body of the rectifying plate, the material of the present invention has a
Since it is age hardened at 0C to have a hardness of iHB550 or higher, its wear resistance is dramatically improved.

According to the current plate configuration shown in FIG. 1, the front part 3a of the current plate 5 has low hardness and is made of a material with excellent ductility, so there is little possibility of cracking at the corner part 30 where the thermal shock force is large. Even at °C, cracks will not develop.

The material of the front part 5a, which is exposed to high temperatures, is 45Or-3ONl cast steel, which is a chromium-nickel steel with excellent oxidation resistance, so it is less likely to be damaged by high-temperature oxidation. Rear part 3 is the weak point
Ceramics, which has significantly better wear resistance than 450r-30Ni cast steel, is attached to the erosion-generating part in b, so there is little risk of erosion. Thermal expansion is also taken into account, so there is no chance of the ceramic cracking.As for the wear resistance of the mounting material, the mounting material is age hardened to increase its hardness and improve its wear resistance. Ceramics will not fall off during use.

Therefore, it is possible to prevent cracking and erosion of the current plate, as well as cracking and falling off of the ceramics in the ceramic-attached current plate, as seen in the past.

In addition, the current plate of the present invention is a composite material of ceramics, which has excellent wear resistance, and chromium-nickel steel, which has thermal shock resistance, so it has excellent performance, and has a long service life, so it is cost-effective. Better than conventional products.

Next, experimental examples and examples of the present invention will be explained.

Experimental Example Table 1 shows the chemical composition of the chromium-nickel-molybdenum steel of the mounting material and the chromium-nickel steel of the rectifier body.The main components are cr: 2y,
s 1%, Ni: 6.94 X%M.

: 2.44N. The current plate body is 450r-3O
It is Ni steel.

Table 2 shows the relationship between aging temperature and hardness of chromium-nickel-molybdenum steel (holding time = 15 hours).When heated to 700~aooc, Purinel hardness HB
) was found to be about 600.

Table 1 Examples 3 baffle plate bodies shown in FIGS. 1 and 2 were cast using a T-Flan mold. Its chemical composition is shown in Table 1. A rectangular ceramic (alumina) tile with pre-drilled mounting holes is stud-welded to the rectifier body using chromium-nickel-molybdenum steel mounting material. Thereafter, the entire rectifier plate was heated to 700C using an electric furnace or other heating device to harden the mounting material. As a result, the hardness of the front part 3a of the current plate 3 shown in FIG. 1 was H8270, the hardness of the rear ceramic was HB762 (Pickus hardness HV870), and the hardness of the mounting material was FiHB600.

As is clear from the above results, according to the present invention, the current plate main body is highly ductile, so cracking can be prevented, and the rear surface where the two lotions occur is coated with extremely hard ceramic as a mounting material that can age harden. Since it is fixed, it has the effect of increasing wear resistance.

[Brief explanation of drawings]

FIG. 1 is a diagram showing one embodiment of the current plate for a coal burner nozzle according to the present invention, and shows a plan view of one of the current plates. FIG. 2 shows a sectional view of the rear part of one of the rectifying plates shown in FIG. FIG. 3 is a chart showing the relationship between the hardness of various materials and the wear rate ratio. FIG. 4 is a perspective view showing the configuration of a general coal burner nozzle, and FIG. 5 is a plan view of a rectifier plate (one sheet) used in the cole burner nozzle of FIG. FIG. 6 to FIG. 10 are diagrams for explaining the structure of a conventional rectifier plate. Sub-agents 1) Meifuku agent Ryo Hagiwara - Sub-agent Atsuo Anzai Figure 3 Hardware () IV)

Claims (1)

[Claims] The rectifying plate body, which is removably inserted into the multi-stage nozzle body, is made of chromium-nickel steel, and ceramics are attached to the surface of the rectifying plate, which is subject to severe wear, using mounting material made of chromium-nickel-molybdenum steel. Rectifier plate for coal burner nozzles.