JPS60101411A - Coal burner nozzle - Google Patents

Abstract

PURPOSE:To improve resistance to thermal impact and resistance to wear, by a method wherein a nozzle is made of a specified material, and heating treatment is applied thereon. CONSTITUTION:A flow uniformizing plate 13, removably attached to a multistage body 1, is formed by chrome-nickel series steel, and the part on the upper stream side of said flow uniformizing plate is age-hardened by high-temperature heating. The chrome-nickel series steel is age-hardened by high-temperature heating and therefore, 25Cr-20Ni, 45Cr-30Ni, 50Cr-50Ni are used. The flow uniformizing plate 13 is formed such that hardening process is not applied on a front 13a, needing resistanc to thermal impact, the hardness thereof is set to HB300 or less, and only a rear 13b, needing resistance to wear, is age-hardened at 600-900 deg.C to set the hardness to HB500 or more. Thus, the front 13a of the uniformizing plate 13 is low in hardness and is formed by a material having excellent ductility, and thereby, even if crack extends to a corner part, the crack is prevented from extending to the front 13a of the flow uniformizing plate 13.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a coal burner nozzle, which is a combustion device for a coal-fired digi.

1 and 2 show a conventional coal burner nozzle. This coal burner nozzle has a nozzle body 1 made of stainless steel with a plurality of grooves 2 formed therein, and a rectifying plate 311 made of high Cr cast iron or stainless cast steel. It is constructed by removably inserting the .

In this coal burner nozzle, pulverized coal pulverized by a mill is supplied through a pulverized coal supply pipe (not shown) connected to the nozzle body 1.
It passes through the rectifier plate 3, is blown out into the furnace, and is combusted. That is, pulverized coal flows in the direction of arrow A (upstream) to arrow B (downstream).

Therefore, as shown in FIG.
In case a, the temperature rises to nearly 1000°C due to the combustion flame of the furnace. In addition, pulverized coal becomes a high-speed powder slurry,
Since the liquid flows along the current plate 3, two lotions are likely to be generated on the current plate 3. Therefore, if the entire baffle plate 3 is made of a single plate and made of wear-resistant material such as high Cr cast iron, the temperature difference between the front part 3a and the rear part 3b of the baffle plate 3 will be As a result, thermal stress is generated, and due to this thermal stress, a crack C occurs from the corner portion 3C of the rectifier plate 3.
There are problems where debris falls to the bottom of the furnace, damaging the tubes and worsening combustion efficiency.

Furthermore, if the entire rectifying plate 3 is made of a single plate and made of heat-resistant material such as stainless steel cast steel, the erosion resistance is inferior to that of the above-mentioned high Cr cast iron.

Therefore, the degree of wear caused by erosion caused by pulverized coal is greater than that of high Cr@iron, and its lifespan is shortened by high Cr.
It will be as small as the size of cast iron.

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

That is, the present invention includes a rectifier plate that is removably inserted into a multi-stage nozzle body and is made of chromium-nickel steel, and the upstream portion of the rectifier plate is age-hardened by heating at a high temperature. Features.

The present invention will be explained below with reference to the drawings.

FIG. 3 shows a current plate of a coal burner nozzle according to the present invention. This current plate 13 is made of chromium-nickel steel. Chromium-nickel steels are age hardened by heating to high temperatures.For example, duplex stainless steels,
25Cr-2ON1, '45Cr-3ONi,
Examples include 50Cr-5ONi.

This current plate 13 has a front part 1.7 a that requires thermal shock resistance.
is not hardened to have a hardness of HB300 or less, and only the rear portion 13b, which requires wear resistance, is age-hardened at 600 to 900°C to have a hardness of H8500 or more. In FIG. 3, the boundary between the front portion 13h and the rear portion 13b (indicated by a broken line) is the front surface 1, ? I made it parallel to e, but the fourth
The boundary portion may follow the outer shape of the rear portion 13b as shown by the broken line in the figure.

However, according to the structure of the lever, since the front part 13a of the current plate 13 is made of a material with low hardness and excellent ductility, even if a crack occurs at the corner part, the crack will not propagate to the front part 13h of the current plate 13. There isn't. Therefore, the current plate 1 as seen in the past
Can prevent cracking in step 3. In addition, since the rectifier plate 13 having both wear resistance and thermal shock resistance can be obtained with a single plate,
It is superior to conventional products in terms of performance and cost.

The rectifier plate 13 is made of chromium-nickel steel, which has even better oxidation resistance.
The front part 1, which is exposed to high temperatures because it is used in
A also has the effect of being less likely to be damaged by high-temperature oxidation.

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

Experimental example Figure 4 shows C: 0.03%, Si: 0.7%, Mn: 0
．． 6%, Cr: 27.2%, Nl: 6.5%, Mo
: Relationship between aging temperature and hardness of chromium-nickel steel (duplex stainless steel) with remaining iron (holding time: 1
5 hours).

According to Figure 4, this chromium-nickel steel has a
It was found that when heated to a temperature in the 900° C. range, it exhibited a Purinelle hardness of 500 or more.

This seems to be because the σ phase precipitates when heated to 600 to 900°C. When this precipitates, ductility and toughness generally decrease, but wear resistance improves.

EXAMPLE The current plate No. 3 shown in FIGS. 3 and 4 was cast using a 7-run mold. Its composition is chromium-nickel steel (C:
0.025%, Si: 0.65%, Mn: 0.55
%, Cr*26.5%, Ni:6.31Mo:2
．． The rear part 13b of the rectifying plate 13 shown in FIG. 3 is inserted into an electric furnace, and the rear part 13b of the rectifying plate 13 shown in FIG. It was cured by heating to ℃.

The hardness of the front part 13m of the current plate 13 shown in FIG. 3 is I(B2
45. The hardness of the rear part 13b is HB580, the hardness of the front part J3a of the rectifying plate 13 shown in FIG. 4 is HB251, and the hardness of the rear part 13 is HB580.
The hardness of b was HB605.

As is clear from the above results, according to the present invention, the front part of the current plate is made ductile to prevent cracking, and the rear part is hardened to improve wear resistance.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a conventional coal burner nozzle, FIG. 2 is a plan view of the current plate, and FIGS. 3 and 4 are plan views showing different embodiments of the coal burner nozzle according to the present invention. FIG. 5 is an explanatory diagram showing the relationship between aging temperature and Purinelle hardness in chromium-nickel steel. DESCRIPTION OF SYMBOLS 1... Nozzle body, 2... Groove, 3, 13... Rectifier plate, 13a... Front part, 13b... Rear part, 13C...
・Front. Applicant's Sub-Agent Patent Attorney Takehiko Suzue Figure 2 Figure 3 Figure 4 Figure 5 l 2( 1( Onwatari (6C)

Claims (1)

[Claims] A coal burner nozzle in which a rectifier plate is removably inserted into a multi-stage nozzle body and is made of chromium-nickel steel, and the upstream portion of the rectifier plate is age-hardened by heating at high temperature.