JP2017025394A - Thermal spray construction method - Google Patents
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- 239000007921 spray Substances 0.000 title claims abstract description 15
- 238000010276 construction Methods 0.000 title claims abstract description 7
- 239000002184 metal Substances 0.000 claims abstract description 55
- 229910052751 metal Inorganic materials 0.000 claims abstract description 55
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 43
- 239000001301 oxygen Substances 0.000 claims abstract description 43
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 43
- 239000000843 powder Substances 0.000 claims abstract description 39
- 239000007789 gas Substances 0.000 claims abstract description 27
- 238000000034 method Methods 0.000 claims abstract description 19
- 238000002485 combustion reaction Methods 0.000 claims abstract description 17
- 239000000463 material Substances 0.000 claims abstract description 17
- 239000012159 carrier gas Substances 0.000 claims abstract description 7
- 230000000694 effects Effects 0.000 claims abstract description 5
- 238000012546 transfer Methods 0.000 claims abstract description 5
- 239000000428 dust Substances 0.000 claims abstract description 4
- 230000020169 heat generation Effects 0.000 claims abstract description 3
- 238000007751 thermal spraying Methods 0.000 claims description 22
- 238000005507 spraying Methods 0.000 claims description 21
- 238000004880 explosion Methods 0.000 claims description 6
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 abstract 2
- 229910001882 dioxygen Inorganic materials 0.000 abstract 2
- 238000007664 blowing Methods 0.000 abstract 1
- 230000005855 radiation Effects 0.000 abstract 1
- 239000011863 silicon-based powder Substances 0.000 description 24
- 239000003832 thermite Substances 0.000 description 17
- 239000006185 dispersion Substances 0.000 description 11
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 7
- 239000000203 mixture Substances 0.000 description 5
- 239000011449 brick Substances 0.000 description 4
- 238000004364 calculation method Methods 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- 229910001111 Fine metal Inorganic materials 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 239000002360 explosive Substances 0.000 description 1
- 239000005350 fused silica glass Substances 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 239000011819 refractory material Substances 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 239000004575 stone Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
Abstract
Description
本発明は、テルミット溶射法による溶射施工方法に関する。 The present invention relates to a thermal spraying method using a thermite thermal spraying method.
工業用窯炉の炉壁を補修する技術の一つとして、耐火原料粉及び金属粉を主材として含む溶射材を、酸素又は酸素を含有するガスを搬送ガスとしてノズル先端から被施工面（被補修面）に吹き付け、金属粉の燃焼発熱を利用して耐火原料を溶融付着させるテルミット溶射法が知られている。 As one of the techniques for repairing the furnace wall of an industrial furnace, a thermal spray material containing refractory raw material powder and metal powder as the main material, oxygen or a gas containing oxygen as a carrier gas from the tip of the nozzle (surface to be processed) There is known a thermite spraying method in which a refractory raw material is melted and deposited by spraying on the repair surface) and utilizing the heat generated by combustion of metal powder.
このようにテルミット溶射法に使用する溶射材は金属粉を含むことから、必然的に発火が生じやすいという問題がある。一般的に発火現象は、以下の３条件が揃った際に発生する。
１）適用金属粉の粉塵濃度が爆発下限界濃度以上であること。
２）発火するに必要な着火源（スパーク）が存在すること。
３）酸素が存在していること。
Thus, since the thermal spray material used for the thermite thermal spraying method contains metal powder, there is a problem that ignition is apt to occur. In general, the ignition phenomenon occurs when the following three conditions are met.
1) The dust concentration of the applicable metal powder is not less than the lower explosion limit concentration.
2) An ignition source (spark) necessary to ignite exists.
3) Oxygen is present.
ここで、テルミット溶射方法では、３）の条件は原理上回避できないため、１）又は２）のいずれか又は双方を回避しておく必要がある。また、２）に関しては、適用する金属粉によって最小着火エネルギーがあることが知られているが、テルミット溶射法では溶射材の搬送時に発生するスパークや配管内静電気といった着火源が生じやすく、さらに金属粉の燃焼発熱によりノズル先端が加熱されることから、２）の条件を回避することは非常に難しい。したがって、テルミット溶射法において発火現象を抑制するには、１）の条件を回避することが基本となる。従来技術も１）の条件に関連するものが多く、例えば特許文献１には、金属粉（金属Ｓｉ粉）のメジアン径が小さいと、微細な金属Ｓｉ粉が凝集して擬似粒子を形成することで、金属Ｓｉ粉の活性が低下し、爆発下限界濃度が急激に高くなって発火しにくくなるこという知見に基づき、金属Ｓｉ粉のメジアン径を１０μｍ以下にする技術が開示されている。 Here, in the thermite spraying method, the condition of 3) cannot be avoided in principle, so it is necessary to avoid either 1) or 2) or both. With regard to 2), it is known that there is a minimum ignition energy depending on the metal powder to be applied. However, in the thermite spraying method, ignition sources such as sparks generated during the transfer of the sprayed material and static electricity in the pipe are likely to occur. Since the nozzle tip is heated by the combustion heat of the metal powder, it is very difficult to avoid the condition 2). Therefore, in order to suppress the ignition phenomenon in the thermite spraying method, it is fundamental to avoid the condition 1). The prior art is also often related to the condition 1). For example, in Patent Document 1, when the median diameter of the metal powder (metal Si powder) is small, the fine metal Si powder aggregates to form pseudo particles. On the basis of the knowledge that the activity of the metal Si powder is reduced and the lower explosion limit concentration is rapidly increased and it is difficult to ignite, a technique for reducing the median diameter of the metal Si powder to 10 μm or less is disclosed.
一方、テルミット溶射法においては、上述した発火現象の他に、金属粉の燃焼発熱による燃焼火焔がノズル先端を経て材料切り出しホッパーまで逆流する逆火現象が発生することが知られている。したがってテルミット溶射法においては、発火現象と逆火現象の双方を抑制する対策を講じることが求められる。この点、特許文献２には、吐出導管の流路を形成する少なくとも一部を樹脂又はゴムで構成することで発火現象を抑制するとともに、吐出導管のストレート部の内径及び噴出ノズルのノズル孔径を限定することで逆火現象を抑制する技術が開示されている。 On the other hand, in the thermite spraying method, in addition to the above-described ignition phenomenon, it is known that a backfire phenomenon occurs in which a combustion flame caused by the heat generated by combustion of metal powder flows back to the material cutting hopper through the nozzle tip. Therefore, in the thermite spraying method, it is required to take measures to suppress both the ignition phenomenon and the flashback phenomenon. In this regard, Patent Document 2 discloses that at least a part of the flow path of the discharge conduit is made of resin or rubber to suppress the ignition phenomenon, and the inner diameter of the straight portion of the discharge conduit and the nozzle hole diameter of the ejection nozzle are set. A technique for suppressing the flashback phenomenon by limiting is disclosed.
しかし、この特許文献２の技術は、噴出ノズル内及び吐出導管内における逆火現象の進展の抑制には効果があるものの、ノズル先端から吐出された金属粉の燃焼発熱による燃焼火焔が逆流するという逆火現象の根本的な発生原因を解消することはできず、実際の溶射施工の現場においては、依然として逆火現象を散見する。 However, although the technique of this patent document 2 is effective in suppressing the progress of the flashback phenomenon in the ejection nozzle and the discharge conduit, the combustion flame due to the combustion heat of the metal powder discharged from the nozzle tip flows back. The root cause of the flashback phenomenon cannot be resolved, and the flashback phenomenon is still common at the actual spraying site.
本発明が解決しようとする第１の課題は、テルミット溶射法による溶射施工方法において逆火現象を抑制することにあり、第２の課題は、逆火現象とともに発火事象を抑制することにある。 The first problem to be solved by the present invention is to suppress the flashback phenomenon in the thermal spraying method by thermite spraying method, and the second problem is to suppress the ignition event together with the flashback phenomenon.
本発明の一観点によれば、次の溶射施工方法が提供される。
酸素又は酸素を含有するガスを搬送ガスとして金属粉を含む溶射材をノズル先端から被施工面に吹き付け、金属粉の燃焼発熱で被施工面に溶融付着させる溶射施工方法において、
ノズル先端からの酸素又は酸素を含有するガスの吐出線流速を（１）式で表される速度Ｖmin（ｍ/ｓ）以上とすることを特徴とする溶射施工方法。
ここで、
λ：酸素と金属粉との平均熱伝導率（ｋｃａｌ／ｍ・℃・ｈｒ）
ρ：酸素と金属粉との平均密度（ｋｇ／Ｎｍ３）
Ｃ：酸素と金属粉との平均比熱（ｋｃａｌ／ｋｇ・℃）
ｂ：燃焼帯長さ（ｍ）
Ｔｂ：燃焼時の最高温度（℃）
Ｔｚ：予熱帯の温度（℃）
Ｔｕ：粉塵雲の初期温度（℃）
ｋ：輻射伝熱の効果を補正する係数でｋ＝１．１
According to one aspect of the present invention, the following thermal spraying method is provided.
In the thermal spraying method in which oxygen or a gas containing oxygen is used as a carrier gas to spray a sprayed material containing metal powder onto the surface to be processed from the nozzle tip, and melt and adhere to the surface to be processed by combustion heat generation of metal powder,
A thermal spraying method characterized in that a discharge line flow rate of oxygen or oxygen-containing gas from a nozzle tip is set to a speed Vmin (m / s) or more represented by the formula (1).
here,
λ: Average thermal conductivity between oxygen and metal powder (kcal / m · ° C · hr)
ρ: Average density of oxygen and metal powder (kg / Nm 3 )
C: Average specific heat of oxygen and metal powder (kcal / kg · ° C)
b: Combustion zone length (m)
Tb: Maximum temperature during combustion (° C)
Tz: Pre-tropical temperature (° C)
Tu: Initial temperature of dust cloud (° C)
k: coefficient for correcting the effect of radiant heat transfer, k = 1.1
この本発明の溶射施工方法において特徴的な前記（１）式は、本発明者らによる以下のような発想及び知見により導き出されたものである。 The characteristic formula (1) in the thermal spraying method of the present invention is derived from the following ideas and knowledge by the present inventors.
まず本発明者らは、逆火現象を抑制する点から、ノズル先端から吐出する、溶射材（金属粉）を含む搬送ガス（酸素又は酸素を含有するガス）の吐出線流速を火焔伝播速度以上にしようという発想を得、さらに、テルミット溶射法における火焔伝搬速度の評価に、可燃混合ガスの火焔伝搬速度Ｖを表すMallard-Chatlierの式を適用しようという発想を得た。 First, in order to suppress the flashback phenomenon, the present inventors set the discharge line flow rate of the carrier gas (oxygen or gas containing oxygen) discharged from the nozzle tip to the flame propagation velocity or higher. Furthermore, the idea of applying the Mallard-Chatlier equation representing the flame propagation velocity V of the combustible gas mixture to the evaluation of the flame propagation velocity in the thermite spraying method was obtained.
Mallard-Chatlierの式とは次の（２）式である。
ここで、
Ｖ：火焔伝搬速度（ｍ／ｓ）
λ：可燃混合ガスの熱伝導率（ｋｃａｌ／ｍ・℃・ｈｒ）
ρ：可燃混合ガスの密度（ｋｇ／Ｎｍ３）
Ｃ：可燃混合ガスの比熱（ｋｃａｌ／ｋｇ・℃）
ｂ：燃焼帯長さ（ｍ）
Ｔｂ：燃焼時の最高温度（℃）
Ｔｚ：予熱帯の温度（℃）
Ｔｕ：可燃混合ガスの初期温度（℃）
The Mallard-Chatlier formula is the following formula (2).
here,
V: Flame propagation speed (m / s)
λ: Thermal conductivity of combustible gas mixture (kcal / m · ° C · hr)
ρ: Density of combustible gas mixture (kg / Nm 3 )
C: Specific heat of combustible gas mixture (kcal / kg · ° C)
b: Combustion zone length (m)
Tb: Maximum temperature during combustion (° C)
Tz: Pre-tropical temperature (° C)
Tu: Initial temperature of combustible gas mixture (° C)
本発明者らは、このMallard-Chatlierの式をテルミット溶射法に適用するにあたり、これまでのテルミット溶射法に関する種々の知見に基づき検討した結果、Mallard-Chatlierの式におけるλ、ρ及びＣは、テルミット溶射法では、それぞれ、酸素と金属粉との平均熱伝導率、平均密度及び平均比熱に置き換え、かつ、Mallard-Chatlierの式におけるｂ、Ｔｂ、Ｔｚ及びＴｕは、使用条件に則した値を代入してテルミット溶射法における火焔伝搬速度を算出した。 The inventors of the present invention applied the Mallard-Chatlier equation to the thermite spraying method, and as a result of examining based on various knowledge about the thermite spraying method so far, λ, ρ and C in the Mallard-Chatlier equation are: In the thermite spraying method, the average thermal conductivity, average density and average specific heat of oxygen and metal powder are respectively replaced, and b, Tb, Tz and Tu in the Mallard-Chatlier formula are values in accordance with the use conditions. The flame propagation velocity in thermite spraying method was calculated by substitution.
しかし、本発明者らが、搬送ガス（酸素又は酸素を含有するガス）の吐出線流速を前記Mallard-Chatlierの式に基づき算出した火焔伝播速度Ｖとして試験したところ、依然として逆火現象が発生した。その原因について本発明者らが検討したところ、テルミット溶射法では、ノズル先端から吐出される搬送ガスに金属粉が含まれることから、その熱伝達は熱伝導に加え輻射伝熱が加わり、結果として、前記のMallard-Chatlierの式に基づき算出される火焔伝播速度よりも、実際の火焔伝播速度が速くなるためと考えられた。 However, when the present inventors tested the discharge line flow velocity of the carrier gas (oxygen or a gas containing oxygen) as the flame propagation velocity V calculated based on the Mallard-Chatlier equation, the flashback phenomenon still occurred. . As a result of the investigation by the present inventors, the thermite spraying method includes metal powder contained in the carrier gas discharged from the tip of the nozzle. It was thought that the actual flame propagation speed was faster than the flame propagation speed calculated based on the above-mentioned Mallard-Chatlier equation.
以上より、本発明者らは、前記のMallard-Chatlierの式をテルミット溶射法に適合するように上述の置き換えを行うとともに、輻射伝熱の効果を補正する係数ｋを導入することに想到した。さらに種々の検討及び試験の結果、係数ｋ＝１．１が適当であることを突き止め、前記（１）式を完成させた。 From the above, the present inventors have conceived that the above-mentioned replacement of the Mallard-Chatlier equation is made so as to be compatible with the thermite spraying method and that a coefficient k for correcting the effect of radiant heat transfer is introduced. Furthermore, as a result of various examinations and tests, it was found that the coefficient k = 1.1 was appropriate, and the above equation (1) was completed.
この（１）式で表される速度Ｖmin（ｍ／ｓ）は、テルミット溶射法における火焔伝搬速度に相当する。したがって、ノズル先端からの酸素又は酸素を含有するガスの吐出線流速を火焔伝搬速度Ｖmin（ｍ／ｓ）以上とすることで、逆火現象を抑制することができる。 The velocity Vmin (m / s) represented by the equation (1) corresponds to the flame propagation velocity in the thermite spraying method. Therefore, the flashback phenomenon can be suppressed by setting the discharge line flow rate of oxygen or oxygen-containing gas from the nozzle tip to the flame propagation velocity Vmin (m / s) or more.
以上のとおり本発明の溶射施工方法によれば逆火現象を抑制することができ、安全な溶射施工が可能となる。 As described above, according to the thermal spraying method of the present invention, the flashback phenomenon can be suppressed, and safe thermal spraying can be performed.
表１は、溶射材に含有する金属粉を金属Ｓｉ粉とし、酸素と金属Ｓｉ粉との固気比、すなわち酸素中の金属Ｓｉ粉分散量（ｋｇ／Ｎｍ３）を変化させて、前記（１）式により火焔伝搬速度Ｖmin（ｍ／ｓ）を算出した結果を示す。また、図１は、その算出結果をプロットしたものである。 Table 1 shows that the metal powder contained in the thermal spray material is metal Si powder, the solid-gas ratio of oxygen and metal Si powder, that is, the amount of metal Si powder dispersed in oxygen (kg / Nm 3 ) is changed, The result of calculating the flame propagation velocity Vmin (m / s) by the equation (1) is shown. FIG. 1 is a plot of the calculation results.
以下、具体的に火焔伝搬速度Ｖmin（ｍ／ｓ）の算出方法について示す。 Hereinafter, a method for calculating the flame propagation velocity Vmin (m / s) will be specifically described.
まず、表１におけるρ、λ、Ｃの算出例を以下に示す。
算出例として、酸素の熱伝導率＝０．０２（ｋｃａｌ／ｍ・℃・ｈｒ）、酸素の密度＝１．１７（ｋｇ／Ｎｍ３）、酸素の比熱＝０．２２（ｋｃａｌ／ｋｇ・℃）、金属Ｓｉ粉の熱伝導率＝７１．９７（ｋｃａｌ／ｍ・℃・ｈｒ）、金属Ｓｉ粉の比熱＝０．１６（ｋｃａｌ／ｋｇ・℃）、金属Ｓｉ粉分散量＝０．１０（ｋｇ／Ｎｍ３）の場合について以下に示す。
ρ＝１．１７＋０．１０＝１．２７（ｋｇ／Ｎｍ３）
λ＝{（１．１７／１．２７）×０．０２}＋{（０．１０／１．２７）×７１．９７}＝５．７０（ｋｃａｌ／ｍ・℃・ｈｒ）
Ｃ＝{（１．１７／１．２７）×０．２２}＋{（０．１０／１．２７）×０．１６}＝０．２２（ｋｃａｌ／ｋｇ・℃）
First, calculation examples of ρ, λ, and C in Table 1 are shown below.
As calculation examples, thermal conductivity of oxygen = 0.02 (kcal / m · ° C. · hr), oxygen density = 1.17 (kg / Nm 3 ), specific heat of oxygen = 0.22 (kcal / kg · ° C.) ), Thermal conductivity of metal Si powder = 71.97 (kcal / m · ° C. · hr), specific heat of metal Si powder = 0.16 (kcal / kg · ° C.), metal Si powder dispersion amount = 0.10 ( kg / Nm 3 ) is shown below.
ρ = 1.17 + 0.10 = 1.27 (kg / Nm 3 )
λ = {(1.17 / 1.27) × 0.02} + {(0.10 / 1.27) × 71.97} = 5.70 (kcal / m · ° C. · hr)
C = {(1.17 / 1.27) × 0.22} + {(0.10 / 1.27) × 0.16} = 0.22 (kcal / kg · ° C.)
平均密度ρは酸素の密度と金属Ｓｉ粉分散量の加算値である。
平均熱伝導率λは、質量分率×酸素と金属Ｓｉ粉各々の熱伝導率の総和であり、平均比熱Ｃは質量分率×酸素と金属Ｓｉ粉各々の比熱の総和である。
上記算出方法により、金属Ｓｉ粉分散量（ｋｇ／Ｎｍ３）の値に応じた平均密度ρ、平均熱伝導率λ、平均比熱Ｃを算出した。
The average density ρ is an added value of the oxygen density and the metal Si powder dispersion amount.
The average thermal conductivity λ is the mass fraction × the sum of the thermal conductivities of the oxygen and the metal Si powder, and the average specific heat C is the sum of the specific heat of the mass fraction × the oxygen and the metal Si powder.
The average density ρ, average thermal conductivity λ, and average specific heat C corresponding to the value of the metal Si powder dispersion amount (kg / Nm 3 ) were calculated by the above calculation method.
また、ｂ、Ｔｂ、Ｔｚ及びＴｕの値は、ｂ＝１ｍｍ（０．００１ｍ）、Ｔｂ＝１６５０℃、Ｔｚ＝６００℃、Ｔｕ＝２５℃とし、これらの値を定数とした。 The values of b, Tb, Tz, and Tu were b = 1 mm (0.001 m), Tb = 1650 ° C., Tz = 600 ° C., and Tu = 25 ° C., and these values were constants.
上記手法により算出したρ、λ、Ｃ及び上記ｂ、Ｔｂ、Ｔｚ及びＴｕの値を式（１）に代入し、金属Ｓｉ粉分散量（ｋｇ／Ｎｍ３）の値に応じて火焔伝搬速度Ｖmin（ｍ／ｓ）を算出し、図１に示す関係を求めた。 Substituting the values of ρ, λ, C and b, Tb, Tz, and Tu calculated by the above method into Equation (1), and the flame propagation velocity Vmin according to the value of the metal Si powder dispersion (kg / Nm 3 ) (M / s) was calculated to obtain the relationship shown in FIG.
このようにあらかじめ図１の関係を求めておけば、あとはその溶射施工における金属Ｓｉ粉分散量（ｋｇ／Ｎｍ３）に応じて、ノズル先端からの酸素又は酸素を含有するガスの吐出線流速（以下、単に「ガスの吐出線流速」という。）を火焔伝搬速度Ｖmin（ｍ／ｓ）以上とすれば良い。これにより、ノズル先端からの溶射材の吐出量が５０（ｋｇ／ｈｒ）以上のような大量吐出を行う場合であっても、逆火事象を抑制できる。 If the relationship shown in FIG. 1 is obtained in advance, the discharge line flow rate of oxygen or oxygen-containing gas from the nozzle tip depends on the metal Si powder dispersion (kg / Nm 3 ) in the thermal spraying process. (Hereinafter, simply referred to as “gas discharge line flow velocity”) may be set to a flame propagation velocity Vmin (m / s) or more. Thereby, even if it is a case where mass discharge of the spraying material discharge amount from a nozzle tip is 50 (kg / hr) or more, a backfire event can be suppressed.
ここで、金属Ｓｉ粉分散量（ｋｇ／Ｎｍ３）は、発火現象を抑制する点から爆発下限界濃度以下とすることが好ましい。したがって、例えば、爆発下限界濃度が０．３ｋｇ／Ｎｍ３の金属Ｓｉを使用する場合、金属Ｓｉ粉分散量（ｋｇ／Ｎｍ３）は０．３ｋｇ／Ｎｍ３を上限とし、この上限の金属Ｓｉ粉分散量＝０．３ｋｇ／Ｎｍ３で溶射施工する場合は、ガスの吐出線流速は図１（前記（１）式）に従い、２６．８０（ｍ／ｓ）以上に設定する。 Here, the amount of metal Si powder dispersion (kg / Nm 3 ) is preferably set to a lower explosion limit concentration or less from the viewpoint of suppressing the ignition phenomenon. Thus, for example, if the lower explosive limit concentration is the use of metal Si of 0.3 kg / Nm 3, a metal Si powder dispersion amount (kg / Nm 3) is capped at 0.3 kg / Nm 3, metallic Si in the upper When thermal spraying is performed at a powder dispersion amount of 0.3 kg / Nm 3 , the gas discharge line flow velocity is set to 26.80 (m / s) or more in accordance with FIG. 1 (the above formula (1)).
なお、金属Ｓｉ粉以外の金属粉においても、同様に前記（１）式に基づきガスの吐出線流速を火焔伝搬速度Ｖmin（ｍ／ｓ）以上に設定すれば良く、この場合も、金属粉分散量（ｋｇ／Ｎｍ３）は爆発下限界濃度以下とすることが好ましい。 For metal powders other than metal Si powder, the gas discharge line flow rate may be set equal to or higher than the flame propagation velocity Vmin (m / s) based on the equation (1). The amount (kg / Nm 3 ) is preferably less than the lower explosion limit concentration.
このように、本発明は、ガスの吐出線流速を火焔伝搬速度Ｖmin（ｍ／ｓ）以上にすることで逆火現象を抑制するもので、逆火現象を抑制する点からはガスの吐出線流速の上限を規定する必要はない。ただし、溶射施工における付着歩留りを確保するなどの点からは、ガスの吐出線流速は、前記(１)式において係数ｋ＝２としたときの速度Ｖmax（ｍ/ｓ）以下とすることが好ましい。 As described above, the present invention suppresses the flashback phenomenon by making the gas discharge line flow velocity equal to or higher than the flame propagation velocity Vmin (m / s). From the viewpoint of suppressing the flashback phenomenon, the gas discharge line There is no need to specify an upper limit for the flow velocity. However, from the standpoint of securing the adhesion yield in the thermal spraying construction, the gas discharge line flow rate is preferably equal to or less than the speed Vmax (m / s) when the coefficient k = 2 in the equation (1). .
表２は、本発明の実施例を比較例と共に示す。 Table 2 shows examples of the present invention along with comparative examples.
金属粉として、酸素雰囲気下で測定した爆発下限界濃度が０．４ｋｇ／Ｎｍ３又は０．４５ｋｇ／Ｎｍ３の金属Ｓｉ粉を使用し、金属Ｓｉ粉１５質量％に対し、非金属の耐火材料粉としてシリカ質粉を８５質量％加え、溶射材とした。シリカ質粉としては、天然石英粉、溶融シリカ粉、珪砂、珪石粉、あるいはこれらの成分を主体とした耐火物粉等が挙げられる。
なお、表２における火焔伝搬速度は、金属Ｓｉ粉分散量の値に対応する火焔伝搬速度を図１から読み取った。
As the metal powder, the explosion lower limit concentration measured under an oxygen atmosphere using a metal Si powder 0.4 kg / Nm 3 or 0.45 kg / Nm 3, to a metal Si powder 15 wt%, the refractory material of the non-metallic As a powder, 85% by mass of siliceous powder was added to obtain a thermal spray material. Examples of the siliceous powder include natural quartz powder, fused silica powder, silica sand, silica stone powder, and refractory powder mainly composed of these components.
In addition, the flame propagation speed in Table 2 read the flame propagation speed corresponding to the value of metal Si powder dispersion amount from FIG.
各例の溶射材を被施工面であるれんが表面に溶射施工し、その溶射施工時の逆火、発火の有無を評価した。 The sprayed material of each example was sprayed on the brick surface, which is the work surface, and the presence or absence of flashback or ignition during the spraying was evaluated.
溶射施工には一般的な溶射装置を用い、タンクの底部に備え付けたテープフィーダをもって溶射材を切り出し、酸素で搬送し、ノズル先端かられんが表面に向けて吹き付けた。れんが表面とノズル先端との距離は８０ｍｍとし、１回あたり３ｋｇの溶射材をれんが表面に吹付けた。 A general thermal spraying apparatus was used for thermal spraying, and the thermal spray material was cut out with a tape feeder provided at the bottom of the tank, transported with oxygen, and sprayed from the nozzle tip toward the brick surface. The distance between the brick surface and the nozzle tip was 80 mm, and 3 kg of spray material was sprayed on the brick surface at one time.
溶射施工時の逆火（発火）の有無は、上述の溶射施工を繰り返し１００回行い、逆火（発火）が１回も発生しなかったものを「無」、逆火（発火）が１回でも発生したものは「有」と評価した。 The presence or absence of backfire (ignition) at the time of thermal spraying is repeated 100 times for the above thermal spraying, and the case where no backfire (ignition) has occurred once is “no” and the backfire (ignition) is 1 time. But what occurred was rated as “Yes”.
各例の金属Ｓｉ粉分散量は、「金属Ｓｉ粉分散量（ｋｇ／Ｎｍ３）＝溶射材吐出量（ｋｇ／ｈｒ）×金属Ｓｉ濃度０．１５÷酸素流量（Ｎｍ３／ｈｒ）」により算出される。 The metal Si powder dispersion amount in each example is “metal Si powder dispersion amount (kg / Nm 3 ) = spraying material discharge amount (kg / hr) × metal Si concentration 0.15 ÷ oxygen flow rate (Nm 3 / hr)” Calculated.
実施例１〜３は、いずれもノズル先端からのガスの吐出線流速を、前記（１）式（図１）から得た火焔伝搬速度Ｖmin（ｍ／ｓ）以上に設定したもので、逆火も発火も発生しなかった。 In each of Examples 1 to 3, the discharge line flow velocity of the gas from the nozzle tip is set to be equal to or higher than the flame propagation velocity Vmin (m / s) obtained from the equation (1) (FIG. 1). There was no ignition.
一方、比較例１は、ノズル先端からのガスの吐出線流速を、前記（１）式においてｋ＝１として得た速度に設定したもので、逆火が発生した。 On the other hand, in Comparative Example 1, the discharge line flow velocity of the gas from the nozzle tip was set to the speed obtained by setting k = 1 in the equation (1), and backfire occurred.
Claims (4)
ノズル先端からの酸素又は酸素を含有するガスの吐出線流速を（１）式で表される速度Ｖmin（ｍ／ｓ）以上とすることを特徴とする溶射施工方法。
ここで、
λ：酸素と金属粉との平均熱伝導率（ｋｃａｌ／ｍ・℃・ｈｒ）
ρ：酸素と金属粉との平均密度（ｋｇ／Ｎｍ３）
Ｃ：酸素と金属粉との平均比熱（ｋｃａｌ／ｋｇ・℃）
ｂ：燃焼帯長さ（ｍ）
Ｔｂ：燃焼時の最高温度（℃）
Ｔｚ：予熱帯の温度（℃）
Ｔｕ：粉塵雲の初期温度（℃）
ｋ：輻射伝熱の効果を補正する係数でｋ＝１．１ In the thermal spraying method in which oxygen or a gas containing oxygen is used as a carrier gas to spray a sprayed material containing metal powder onto the surface to be processed from the nozzle tip, and melt and adhere to the surface to be processed by combustion heat generation of metal powder,
A thermal spraying method characterized in that a discharge line flow rate of oxygen or oxygen-containing gas from a nozzle tip is set to a speed Vmin (m / s) or more represented by the formula (1).
here,
λ: Average thermal conductivity between oxygen and metal powder (kcal / m · ° C · hr)
ρ: Average density of oxygen and metal powder (kg / Nm 3 )
C: Average specific heat of oxygen and metal powder (kcal / kg · ° C)
b: Combustion zone length (m)
Tb: Maximum temperature during combustion (° C)
Tz: Pre-tropical temperature (° C)
Tu: Initial temperature of dust cloud (° C)
k: coefficient for correcting the effect of radiant heat transfer, k = 1.1
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| JP2020059899A (en) * | 2018-10-12 | 2020-04-16 | 黒崎播磨株式会社 | Flame spraying method |
| JP2020190011A (en) * | 2019-05-21 | 2020-11-26 | 黒崎播磨株式会社 | Flame splay method |
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| JPH09248497A (en) * | 1996-01-12 | 1997-09-22 | Sumitomo Metal Ind Ltd | Method and apparatus for flame spraying of refractory |
| JP2007284707A (en) * | 2006-04-12 | 2007-11-01 | Kurosaki Harima Corp | Thermal spraying method |
| JP2010532252A (en) * | 2007-07-05 | 2010-10-07 | フィブ−サーヴィシーズ アンテルナシオナル ソシエテ アノニム | Method and apparatus for introducing and spraying powder material into a carrier gas |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JPH09248497A (en) * | 1996-01-12 | 1997-09-22 | Sumitomo Metal Ind Ltd | Method and apparatus for flame spraying of refractory |
| JP2007284707A (en) * | 2006-04-12 | 2007-11-01 | Kurosaki Harima Corp | Thermal spraying method |
| JP2010532252A (en) * | 2007-07-05 | 2010-10-07 | フィブ−サーヴィシーズ アンテルナシオナル ソシエテ アノニム | Method and apparatus for introducing and spraying powder material into a carrier gas |
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| JP2020059899A (en) * | 2018-10-12 | 2020-04-16 | 黒崎播磨株式会社 | Flame spraying method |
| JP2020190011A (en) * | 2019-05-21 | 2020-11-26 | 黒崎播磨株式会社 | Flame splay method |
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