JP2661978B2 - Surface burner - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface burning burner in which a number of small flame holes are formed in a far-infrared radiator.

[Conventional technology]

Conventionally, far-infrared radiators have been made of ceramics.

[Problems to be solved by the invention]

However, the shape of ceramics could not be arbitrarily selected due to restrictions on the molding surface, and the mechanical strength and the strength against thermal shock were insufficient, so that there was a defect in durability.

An object of the present invention is to provide a surface combustion burner which is excellent not only in far-infrared radiation characteristics but also in moldability and durability.

[Means for solving the problem]

The feature of the first invention is that the far-infrared radiator that forms a number of small flame holes in the surface combustion burner is made of Fe, Cr and Al.
Most of the length is 2μ on the surface of stainless steel containing
m having an alumina whisker of at least m, and a surface roughness Ra of the surface is 0.5 μm or more,
The surface with the alumina whisker is arranged on the combustion surface side, and the operation is as follows.

(Operation)

In other words, if the far-infrared radiator is formed of any material, far-infrared radiation can be efficiently performed, and the shape can be arbitrarily selected, and the mechanical strength and the strength against thermal shock can be sufficiently improved. The following facts became clear as a result of pursuit through experiments.

The surface of stainless steel containing Fe, Cr, and Al is mostly formed with alumina whiskers having a length of 2 μm or more and a roughness Ra of 0.5 μm or more. , A high emissivity comparable to that of ceramics was obtained.

Further, since the alumina whiskers have sufficiently grown, they do not peel off due to external force or thermal shock. Besides, the surface roughness
Since Ra is sufficiently large, the density of the alumina whisker is increased, which also suppresses the peeling of the alumina whisker. Whisker peeling was completely prevented.

Therefore, when the above-described stainless steel with alumina whiskers is used to form the far-infrared radiator for forming the small flame holes of the surface combustion burner and the surface having the alumina whiskers is disposed on the combustion surface side, efficient far-infrared radiation can be realized only. Instead, the shape of the far-infrared radiator can be made to be an optimum shape suitable for the application, and the durability of the far-infrared radiator can be sufficiently improved.

By the way, in order to improve the moldability, it is conceivable to apply a well-known far-infrared radiation paint on the surface of (a) ordinary stainless steel, or (b) use a wire net as a far-infrared radiator. In the case of item b), the paint peels off early,
The far-infrared radiation performance is reduced, and the item (b) has low far-infrared radiation performance and is liable to change its shape due to heat distortion. It can combine all functions, moldability and strength.

[Means for solving the problem]

The feature of the second invention is that the far-infrared radiator which forms a number of small flame holes in the surface combustion burner is 20 to 35% by weight.
Cr, 0.5 to 5% by weight of Mo, 3% by weight or less of Mn and 3% by weight or less of Si Fe-Co-Mo stainless steel containing a high-temperature oxide film of 0.2 mg / cm ² or more The surface with the high-temperature oxide film is disposed on the combustion surface side, and the operation is as follows.

(Operation)

In other words, if the far-infrared radiator is formed of any material, far-infrared radiation can be efficiently performed, and the shape can be arbitrarily selected, and the mechanical strength and the strength against thermal shock can be sufficiently improved. Further investigations have revealed the following facts.

The composition of stainless steel is 20-35 wt% Cr, 0.5-5
% Of Mo, 3% by weight or less of Mn, and 3% by weight or less of Si.
When a high-temperature oxide film of ² mg / cm ² or more was provided and far infrared rays were emitted from the surface by heating stainless steel, a high emissivity comparable to that of ceramics was obtained.

In addition, the high-temperature oxide film with a concentration of 0.2 mg / cm ² or more does not peel off due to external force or thermal shock, can be easily formed into any shape by pressing, etc., and completely prevents peeling of the high-temperature oxide film during use. Was.

Therefore, in the stainless steel with high temperature oxide film described above,
Forming a far-infrared radiator for forming a small flame hole of a surface combustion burner, and arranging the surface having a high-temperature oxide film on the combustion surface side,
Not only can efficient far-infrared radiation be realized, but also the shape of the far-infrared radiator can be made optimal according to the application, and the durability of the far-infrared radiator can be sufficiently improved.

〔The invention's effect〕

As a result, it has become possible to provide a surface combustion burner which is not only excellent in far-infrared radiation performance but also excellent in moldability and durability.

〔Example〕

 Next, an embodiment will be described with reference to the drawings.

Attach far infrared radiator (2) to burner body (1),
Forming a number of small flame holes (3) in the far-infrared radiator (2);
A gas permeable heat insulating material (4) such as glass wool is disposed on the entire back surface of the far-infrared radiator (2), and a nozzle (5) for jetting gas fuel into the burner body (1) is provided. ) Is formed in the burner body (1) to absorb the outside air with the gas jet from the burner body (1).

That is, the gas fuel from the nozzle (5) and the combustion air from the air port (6) in such an amount that the gas fuel can be completely burned are mixed in the burner body (1), and the air-fuel mixture is made into small flame holes ( The mixture is distributed and supplied to 3), and the air-fuel mixture from the small flame hole (3) is surface-burned on the combustion surface side of the far-infrared radiator (2), and the structure of the heat insulating material (4) prevents flashback. I have.

In addition, the efficient infrared radiation from the far-infrared radiator (2) enables mild heating and improved heating performance. Next, the details of the far-infrared radiator forming the far-infrared radiator (2) will be described. explain.

(Example 1) The far-infrared radiating material has alumina whiskers on the surface of stainless steel containing Fe, Cr and Al, and the surface is arranged on the combustion surface side.

The content of Cr is desirably 12% by weight or more from the viewpoint of rust prevention and 28% by weight or less from the viewpoint of preventing embrittlement.

Al content is 2% by weight from the alumina whisker formation surface
As described above, the content is preferably 6% by weight or less from the viewpoint of preventing embrittlement.

When C, Si, and Mn are contained in stainless steel, the content of C is reduced to 0.03% by weight or less from the crack prevention surface, the content of Si is reduced to 1% by weight or less from the ductility maintaining surface, and the content of Mn is deteriorated in toughness. It is desirable that the content be 1% by weight or less from the viewpoint of preventing or maintaining high-temperature oxidation resistance.

0.5% by weight or less of Ti or Zr to improve toughness and oxidation resistance
May be contained in stainless steel, or a rare earth element such as Y, Ce, La, Nd or the like of 0.3% by weight or less may be contained in stainless steel in order to improve peel resistance.

Most of the alumina whiskers have a length of 2 μm or more, so that it is possible to improve the far-infrared radiation efficiency and prevent the peeling of the alumina whiskers due to external force.

In order to form alumina whiskers of 2 μm or more, it is necessary to oxidize stainless steel in an oxidizing atmosphere at a temperature of 850 to 1000 ° C. and at a high temperature of 4 hours or more, and preferably at 920 to 930 ° C.
High temperature oxidation treatment is performed for Hr.

In order to form alumina whiskers in a high-density state and to improve the far-infrared radiation efficiency and to prevent the peeling of alumina whiskers due to external force more effectively, the surface roughness Ra of the stainless steel should be 0.5 μm or more. It is. The roughness Ra is a center line average roughness (JIS B0601) measured by a stylus type surface roughness measuring instrument (JIS B0651).

Before the high-temperature oxidation treatment, blast treatment is performed to make the surface roughness Ra 0.5 μm or more.

The blasting is performed by, for example, projecting abrasive grains of alumina or silicon carbide having a roughness of 100 to 400 or an iron ball or iron grid having a diameter of 0.05 to 1.0 mm.

When the Al content is less than 3% by weight or when the work distortion of the stainless steel surface due to the blast treatment is insufficient, the pre-oxidation is performed before the high-temperature oxidation treatment in order to make the length and density of the alumina whiskers sufficient. It is desirable to perform processing.

In the preliminary oxidation treatment, in order to improve the formation of alumina whiskers, the O ₂ concentration in the atmosphere is 0.1% or less, the heating temperature is 700 ° C. or more, and the treatment time is 10 seconds or more.
The heating temperature is set to 1000 ° C or less to prevent embrittlement.

(Example 2) The far-infrared radiation material has a high-temperature oxide film of 0.2 mg / cm ² or more on the surface of stainless steel containing Fe, Cr, and Mo, and the surface is disposed on the combustion surface side. I have.

Cr content should be 20% by weight or more from the viewpoint of improving corrosion resistance.
And it is necessary to make it 35 weight or less from the viewpoint of embrittlement prevention and easy workability.

Mo content is 0.5% by weight or more from the viewpoint of improving corrosion resistance,
In addition, the content needs to be 35% by weight or less from the viewpoints of embrittlement prevention and easy workability.

When Mn is contained, the content needs to be 3% by weight or less in order to prevent deterioration of toughness and oxidation resistance at high temperatures.

When Si is contained, oxidation resistance at high temperatures is improved and high-temperature oxidation treatment is facilitated.
The following is desirable.

When one or more selected from the group consisting of Ti, Nb, and Zr is included, the content is reduced to 0.3% by weight or less,
It is desirable to improve toughness and oxidation resistance.

When one or more members selected from the group consisting of La, Ce, Nd, and Y are contained, it is desirable to reduce the content to 0.3% by weight or less to improve the peeling resistance of the high-temperature oxide film.

To form a high-temperature oxide film, it is desirable to heat stainless steel at 900 to 1200 ° C. in an oxidizing atmosphere.

In other words, if the heating temperature is lower than 900 ° C., the diffusion of Cr in the stainless steel is slow, so that it escapes as oxide on the surface.
The diffusion replenishment amount of Cr from the inside to the surface is reduced with respect to the amount of Cr, and a layer having a low Cr content is formed over a thickness of several tens of μm on the surface side, and the corrosion resistance is significantly deteriorated.
By heating as described above, the diffusion rate of Cr inside becomes sufficiently large, and sufficient corrosion resistance is obtained. The heating temperature is 12
If the temperature exceeds 00 ° C., the high-temperature deformation of the stainless steel becomes so severe that it cannot be used practically. However, if heated at 1200 ° C. or lower, the deformation can be sufficiently suppressed.

A heating program for forming a high-temperature oxide film at a concentration of 0.2 mg / cm ² or more can be appropriately selected. In general, when the temperature is 900 ° C. or more and less than 1100 ° C., the temperature is T (° C.) and the time is t (mi).
The heating time is set so that t ≧ 142.5−0.125T as n).
If the temperature is lower than 00 ° C., heat for 5 minutes or more. Note that the heating temperature may be appropriately changed during heating.

Air, oxygen-enriched gas, steam-enriched gas, combustion gas, and other suitable gases can be used to create an oxidizing atmosphere.

The high-temperature oxide film is optimally 0.5 to ² mg / cm ^2, and is desirably 10 mg / cm ² or less to make it difficult to peel off.

It is desirable to increase the surface roughness of the stainless steel so as to increase the radiation area of far-infrared rays. In this case, the surface is subjected to processing distortion by blasting or dull skin pass rolling before heating.

(Experimental example)

 Next, an experimental example will be described.

<Experimental Example 1> A steel sheet having the composition shown in Table 1 below was prepared from stainless steel treated in the order of rolling, annealing, and pickling.

Incidentally, the steel plate is 10 cm square and 1 mm thick, and A-1 to A-3 are compositions corresponding to the stainless steel of the present invention,
B-1 and B-2 are compositions corresponding to conventional products.
Is a percentage by weight.

The samples of A-1 to A-3 in Table 1 were subjected to blast treatment, pre-oxidation treatment, or part or all of high-temperature oxidation treatment, and the treatment conditions were changed to adjust the roughness Ra, the length of the alumina whiskers, and the emissivity. It measured and obtained the result of Table 2 below.

Note that in the blasting process, SiC is a case where a No. 180 SiC shot is used, and Fe is a case where a 0.1 mm iron ball shot is used. The emissivity is at a wavelength of 5 to 15 at 400 ° C.
The far-infrared radiation intensity of μm is shown as an average ratio with blackbody radiation.

From the results in Table 2, it can be seen that most of the surfaces have alumina whiskers having a length of 2 μm or more, and the surface roughness Ra is
It has been found that a high emissivity of 0.7 or more can be obtained when the thickness is 0.5 μm or more.

Next, Samples Nos. 1 to 5 in Table 2 (products of the present invention)
A sample obtained by coating a sample of B-1 and B-2 in Table 1 with a commercially available alumina / silica-based far-infrared paint (conventional product)
Were subjected to the following heating and cooling repetition tests (a) and (b).

(A) After heating to 700 ° C, let it cool in the air for 20 minutes and repeat the heating and cooling. (B) After heating to 700 ° C, cool by spraying water for 20 minutes and repeat the heating and cooling.

As a result, all of the products of the present invention did not change at all after repeated heating and cooling 20 times, and had good properties that did not peel off due to external force or thermal shock. However, the conventional B
-1 indicates that the paint was cracked by repeating heating and cooling 17 times in the above test (a), and the conventional B-2
In the test of item (b) above, brown spots were formed on the paint by repeating heating and cooling five times, and in each case, the paint was easily peeled off by external force or thermal shock.

In other words, since the product of the present invention does not peel off due to external force or thermal shock, it can be easily formed into an arbitrary shape by pressing or the like, and even when used as a far-infrared radiator for forming small flame holes of a surface burning burner, It has been found that durability can be sufficiently improved.

<Experimental example 2> A stainless steel sheet having the composition shown in Table 3 below was prepared.

The steel plate is 10 cm square and 1 mm thick. C-1 to C-6 are commercially available annealed and pickled stainless steels, and D-1 and D-2 are stainless steels which were experimentally melted, rolled, annealed, and pickled. It is. The unit in Table 3 is% by weight.

The samples in Table 3 were subjected to surface treatment or high-temperature oxidation treatment without surface treatment, changing the treatment conditions, measuring the roughness Ra, the amount of the high-temperature oxide film, the emissivity, and examining the corrosion resistance. The results in Table 4 below were obtained.

In the surface treatment, SiC is a blast treatment using a No. 180 SiC shot, Fe is a blast treatment using a 0.1 mm iron ball shot, and rolling is a dull skin pass that roughens the surface by rolling with a rough surface roll. This is a rolling process.

The amount of the high-temperature oxide film is a value obtained by measuring the weight of the stainless steel sheet before and after the high-temperature oxidation treatment, obtaining the weight increase per unit surface area, and multiplying the increase weight by 3.3. That is, high-temperature oxidation film is made of mostly Cr ₂ O ₃ According to X-ray analysis, because the molar weight ratio of Cr ₂ O ₃ and _{O 2 (Cr 2 O 3 /} O 2) of 3.3, as described above The amount of the high temperature oxide film was determined.

 The emissivity was determined in the same manner as in Experimental Example 1.

For corrosion resistance, a salt spray test (JIS Z2371) was performed for 4 hours.

From the results in Table 4, it was found that Fe-Cr-Mo stainless steel
It contains 0.2% by weight of Cr, 0.5% to 5% by weight of Mo, 3% by weight or less of Mn, and 3% by weight or less of Si.
It was found that, for those having a high-temperature oxide film of g / cm ² or more, that is, Nos. 1 to 5, a high emissivity of 0.7 or more was obtained, and it was excellent in corrosion resistance and was not peeled off by external force.

Therefore, it can be used as a far-infrared radiator for forming small flame holes of a surface combustion burner.

(Another embodiment)

 Next, another embodiment will be described.

The shape of the far-infrared radiator (2) can be freely changed, and for example, the combustion surface can be formed into a spherical or trough-shaped convex or concave surface, a box shape, a flat shape, or the like.

The small flame holes (3) may be appropriately changed in size, number, arrangement, etc., and may be formed in a planar shape without excessively extending the flame.

The specific structure and application of the surface combustion burner are not limited. For example, a fan for supplying combustion air may be provided, or a mixture such as a perforated plate may be uniformly distributed to the small flame holes (3) in the burner body (1). For example, it is possible to provide a dispersing tool.

In the claims, reference numerals are provided for convenience of comparison with the drawings, but the present invention is not limited to the structure and the method of the accompanying drawings.

[Brief description of the drawings]

 The drawings are sectional views showing an embodiment of the present invention. (2): Far infrared radiator; (3): Small flame hole.

Claims (2)

(57) [Claims] 1. A surface burning burner in which a number of small flame holes (3) are formed in a far-infrared radiator (2), wherein the far-infrared radiator (2) contains stainless steel containing Fe, Cr and Al. Most of the surface of the steel has alumina whiskers having a length of 2 μm or more, and the surface roughness Ra of the surface is 0.5 μm or more. Surface burning burners located. 2. A surface burning burner in which a plurality of small flame holes (3) are formed in a far-infrared radiator (2), wherein the far-infrared radiator (2) is 20 to 35% by weight of Cr, 0.5% by weight. ~ 5% by weight
Mo, 3% by weight or less of Mn and 3% by weight or less of Si: Fe-Cr-Mo stainless steel containing a high-temperature oxide film of 0.2 mg / cm ² or more on the surface thereof. Consisting of
A surface combustion burner wherein the surface with the high-temperature oxide film is disposed on a combustion surface side.