JP2004332080A - Method and device for generating atmospheric gas for carburizing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for generating an atmospheric gas for carburizing where a converted gas with a high CO concentration can stably efficiently be generated for a long period of time without causing clogging or the like due to the generation of soot using a conversion furnace system. <P>SOLUTION: A gaseous mixture of gaseous hydrocarbon, carbon dioxide and air is introduced into a furnace, and exothermic reaction and endothermic reaction are caused to produce an intermediate converted gas. Thereafter, the intermediate converted gas is additionally supplied with gaseous hydrocarbon to cause reforming reaction. In the gaseous mixture used for the reaction of producing the intermediate converted gas, a mixing ratio to control the temperature of an endothermic band in the furnace to ≥800°C is made, and the balance between the exothermic reaction and the endothermic reaction is taken, so that the generation of soot is suppressed. The intermediate converted gas is additionally supplied with gaseous hydrocarbon as an enrich gas to cause reforming reaction, so that the atmospheric gas for carburizing with a high CO concentration is obtained. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００１４】
熱分解したブタンガスは炭素と水素になるため、改質反応が起こらず、一酸化炭素が生じない。
【００１５】
従来の変成炉を用いて、ブタンガスを空気変成、酸素変成、および二酸化炭素変成したときの反応筒内の温度分布の実測結果をそれぞれ図３に示す。図の下側が原料ガスの入口であり、通常の空気変成に比べて酸素変成の場合、入口部の温度が高くなっている。［表１］には図３のデータを得たときの各ガス流量を示し、［表２］には反応により発生したガス中の各成分濃度を示す。また、［表３］には発生ガス中の煤の発生状況を示す。
【００１６】
【表１】

【００１７】
【表２】

【００１８】
【表３】

【００１９】
二酸化炭素とブタンガスによる変成（二酸化炭素変成）の場合、酸素変成とは逆に反応筒入口部の温度が下がり過ぎるという問題があることが判明した。原料ガス中の二酸化炭素の流量比率を上げると、吸熱量が多くなり温度が下がっていく。この変成炉の場合、１４ｍ^３ ／ｈが標準の発生ガス量であるが、１０ｍ^３ ／ｈ以上発生させることができなかった。すなわち、図３から判るように、１０ｍ^３ ／ｈで入口温度が７７７℃である。これ以上変成ガス量を増やせば７５０℃以下に温度が下がってしまう。４００〜７５０℃の間では、（５）式に示すブードワ反応によって、一酸化炭素が二酸化炭素と炭素（煤）に分解してしまう。従って、入口温度を７５０℃以上に保つために、これ以上変成ガス量を増やすことができない。
２ＣＯ→ＣＯ_２ ＋［Ｃ］ ・・・・（５）
【００２０】
このようなことから、従来の変成炉方式によれば、種々の提案にも係わらず、煤を発生することなく長時間にわたって高ＣＯ濃度の変成ガスを生成することは極めて困難である。
【００２１】
本発明はこのような実情に鑑みてなされたもので、変成炉方式を用いて、煤の発生による閉塞等を生じることなく、長時間にわたって高ＣＯ濃度の変成ガスを安定して効率的に発生することのできる方法と、その方法を用いるのに適した装置の提供を目的としている。
【００２２】
【課題を解決するための手段】
上記の目的を達成するため、本発明の浸炭用雰囲気ガスの発生方法は、炭化水素ガスを含む原料ガスを反応させることにより、一酸化炭素と水素とを含む浸炭用雰囲気ガスを発生する方法であって、炭化水素ガスと二酸化炭素および空気の混合ガスを所定の混合比のもとに炉内に導いて発熱反応および吸熱反応させて中間変成ガスを生成した後、その中間変成ガスに対して炭化水素ガスを追加供給して改質反応させることにより浸炭用雰囲気ガスを生成するとともに、上記中間変成ガスを生成する反応に用いる混合ガスは、炉内での吸熱帯の温度が８００℃以上を維持する混合比とすることによって特徴づけられる（請求項１）。
【００２３】
ここで、本発明方法においては、上記改質反応において二酸化炭素濃度が一定となるように炭化水素ガスの追加供給量を調整する方法を好適に採用することができる（請求項２）。
【００２４】
また、本発明の浸炭用雰囲気ガスの発生装置は、炭化水素ガスを含む原料ガスを反応させることにより、一酸化炭素と水素とを含む浸炭用雰囲気ガスを発生するための装置であって、互いに直列に接続され、かつ、それぞれに触媒層を内蔵する第１および第２の反応筒と、上記第１の反応筒に対して炭化水素ガスと二酸化水素および空気を所定の混合比のもとに導入する流量調整手段と、上記第２の反応筒内の二酸化炭素濃度を検出する検出手段と、その検出結果が一定となるように炭化水素ガスの追加供給量を自動的に調整する流量制御手段を備えていることによって特徴づけられる（請求項３）。
【００２５】
そして、この本発明装置においては、上記流量調整手段を、炭化水素ガス、二酸化炭素および空気の３種のガスのうち、２種のガスを所定の混合比のもとに混合する第１の混合手段と、その混合ガスに対してもう１種のガスを所定の混合比のもとに混合する第２の混合手段によって構成すること（請求項４）が好ましい。
【００２６】
本発明の浸炭用雰囲気ガスの発生方法においては、炭化水素ガスと二酸化炭素および空気とを混合したガスを原料ガスとし、反応を２段に分け、１段目では原料ガスを反応させて中間変成ガスを発生させる。この１段目の反応では、煤が発生するような混合比として無理にＣＯ濃度を高くするようなことはせずに、炭化水素ガスの燃焼反応（前記（２）式に例示される発熱反応）と改質反応（前記（３），（４）式に例示される吸熱反応）とのバランスを考慮した混合比とすることによって、反応筒内の吸熱帯の温度を８００℃以上に維持して煤の発生を抑制する。そして、２段目の反応において、中間変成ガスに対して炭化水素ガスを追加供給して改質反応させることにより、高ＣＯ濃度の浸炭用雰囲気ガスを生成することができる。
【００２７】
そして、２段目の反応においては、二酸化炭素の濃度を検出し、その検出結果が一定となるように炭化水素ガスの追加供給量を制御することにより、安定して高ＣＯ濃度の浸炭用雰囲気ガスを得ることができる。
【００２８】
一方、本発明の浸炭用雰囲気ガスの発生装置は、以上の本発明方法の適用を容易化した装置であり、上記した１段目と２段目の反応をそれぞれ個別に行うための第１と第２の反応筒を設けてこれらを互いに直列に接続するとともに、第２の反応筒には、二酸化炭素の濃度の検出手段とその検出結果に基づいて炭化水素ガスの追加供給量を制御する流量制御手段を有している。
【００２９】
そして、この本発明装置において、第１の反応筒に導入する混合ガスの調整手段として、原料となる３種のガスのうちの２種を混合する第１の手段と、その混合後のガスに対してもう１種のガスを混合する第２の混合手段によって構成することにより、簡単な操作のもとに３種のガスの混合比を随意に変更することが可能であり、かつ、混合比も正確なものとすることができる。
【００３０】
なお、本発明において用いられる好適な炭化水素ガスとしては、ブタンガスやＬＰＧなどを挙げることができる。
【００３１】
【発明の実施の形態】
以下、図面を参照しつつ本発明の実施の形態について説明する。
図１は本発明の実施の形態の概略構成を示す系統図である。
【００３２】
反応に用いられる原料ガスは、ブタンガスと二酸化炭素および空気の３種類であり、これらのうち、空気はエアブリーザ１により第１のキャブレタ２に導入され、二酸化炭素は二酸化炭素供給源３から圧力比例弁４を介して同じく第１のキャブレタ２に導入され、設定された混合比のもとに混合される。第１のキャブレタ２により混合されたガスは第２のキャブレタ５に導入される。この第２のキャブレタ５には、また、ブタンガス供給源６からのブタンガスが圧力比例弁７を介して導入されており、この第２のキャブレタ５により、二酸化炭素および空気からなる混合ガスと、ブタンガスとが設定された混合比のもとに混合される。従って、第１のキャブレタ２または第２のキャブレタ５のいずれかの混合比の設定を調整することにより、３種のガスの混合比を随意に変更することができる。
【００３３】
第２のキャブレタ５からの混合ガスは、ルーツブロワ８を介して第１の反応筒９にその底部から導入される。第１の反応筒９は、その内部にニッケル触媒が充填されているとともに、加熱室９ａ内に設けられており、この第１の反応筒９内での混合ガスの反応により、中間変成ガスが生成される。この中間変成ガスは第１の反応筒９の頂部の出口部分に設けられたトップウォータジャケット（図示略）とガスクーラー１０によって急激に冷却される。この急冷により、中間変成ガスのブードア反応による煤の発生を防止すると同時に、ガス中の水分が除去される。
【００３４】
水分除去後の中間変成ガスは、モータバルブ１１を介してブタンガス供給源６から供給されるブタンガスとともに、第２の反応筒１２内にその底部から導入される。この第２の反応筒１２は、第１の反応筒９と同様に、その内部にニッケル触媒が充填されているとともに、加熱室１２ａ内に設けられている。この第２の反応筒１２では、第１の反応筒９から供給される中間変成ガス内に含まれるＣＯ_２ とＨ_２ Ｏを、エンリッチガスとしてのブタンガスでＣＯとＨ_２ に改質する。
【００３５】
第２の反応筒１２により生成されたガスは、第１の反応筒９と同様にトップウォータジャケット（図示せず）およびガスクーラー１３によって急冷され、背圧調整弁１４で所要の圧力に調整されたうえで、バルブ１５を通じて浸炭炉に供給される。なお、余ったガスはガスブリーザ１６で燃やされて廃棄される。
【００３６】
第２の反応筒１２へのブタンガスの供給量は、当該第２の反応筒１２により生成されたガスの二酸化炭素濃度を赤外線式のＣＯ_２ 分析計１７で測定し、その濃度の測定結果が設定された一定値を維持するように前記したモータバルブ１１の弁開度を自動的に調整することによって制御される。これにより、第２の反応筒１２における改質反応により発生するガス中の二酸化炭素濃度が一定に維持され、カーボンポテンシャルが正確に所望値に維持される。
【００３７】
次に、以上の装置を用いて実際に浸炭用雰囲気ガスを生成する具体的な例を述べる。
第１の反応筒９への各ガスの流量と、第２の反応筒１２へのブタンガス（エンリンチガス）の流量、およびその第２の反応筒１２で発生したガスの流量を［表４］に示す。また、［表５］には各反応筒内でのＣＯ，ＣＯ_２ およびＣＨ_４ の濃度を示す。更に、図２には、第１の反応筒９内での温度分布を示す。そして、第１および第２の反応筒９および１２内の煤の発生状況を［表６］に示す。第１の反応筒９内における吸熱帯の温度が８５０℃を越えているため、煤の発生がなく、長期連続運転が可能であることが確かめられた。
【００３８】
【表４】

【００３９】
【表５】

【００４０】
【表６】

【００４１】
以上の例において、第１の反応筒９内における反応式は下記の（６）式に示す通りである。なお、この式（６）において、反応後の各ガスの後ろの括弧内は濃度を示している。
【００４２】

【００４３】
また、Ｃの総モル数は５．０５、（ＣＯ＋ＣＯ_２ ）のＯ_２ の量（モル数換算）２．６２８、Ｏ_２ の総モル数２．８３、余りのＯ_２ のモル数０．２００、余りのＯのモル数０．４００であった。発生ガスの総モル数は１３．９４２で、発生ガス流量は１３．９ｍ^３ ／ｈである。
【００４４】
そして、第１の反応筒９で発生したガスを急冷により水分を除去した後の成分は、

となり、その総モル数は１３．５４２、ガス流量は１３．５ｍ^３ ／ｈである。
【００４５】
第２の反応筒１２内における反応式は、発生する各ガスの濃度を併せて示せば、

であり、Ｃの総モル数が５．２７、ブタン分解により新たに発生するＨ_２ のモル数が０．２７０である。また、この段階で発生したガスの総モル数が１４．０２９で、その流量は１４．０ｍ^３ ／ｈであった。
【００４６】
以上の各反応における熱収支を、ブタン１ｍ^３ 当たりで計算した結果を［表７］に示す。
【００４７】
【表７】

【００４８】
この［表７］に示される通り、熱収支の合計は発熱反応となり、消費電力が極めて少なくてすむことが明らかになった。
【００４９】
なお、以上の例では、炭化水素ガスとしてブタンガスを用いた例を示したが、プロパンガスであっても同等の目的効果を達成することができることが確かめられている。
【００５０】
【発明の効果】
本発明によれば、ＣＯ濃度３５％以上の変成ガスを安定して発生することができ、しかも反応時に煤が発生してガス流路等を閉塞することがないので、長期間にわたって連続運転が可能である。
【００５１】
また、高いＣＯ濃度の雰囲気ガスが得られるため、変成炉方式であってもメタノール方式と同等の高速の浸炭速度が得られ、従ってメタノール供給設備を用いることなく、市街地の工場でも高速浸炭を実現することができる。
【００５２】
更に、本発明においては熱収支の合計を発熱反応とすることができ、従来の変成炉に比して、消費電力を大幅に低減させることができる。発生ガス量１４ｍ^３ の変成炉の場合について比較したとき、従来の変成炉の消費電力が約８ｋＷであったのに対し、本発明の適用した場合には約２ｋＷであることが確かめられた。
【図面の簡単な説明】
【図１】本発明の実施の形態の概略構成を示す系統図である。
【図２】本発明の実施の形態における第１の反応筒内の温度分布の実測結果を示すグラフである。
【図３】従来の変成炉を用いて、ブタンガスを空気変成、酸素変成、および二酸化炭素変成したときの反応筒内の温度分布の実測結果を示すグラフである。
【符号の説明】
１ エアブリーザ
２ 第１のキャブレタ
３ 二酸化炭素供給源
４ 圧力比例弁
５ 第２のキャブレタ
６ ブタンガス供給源
７ 圧力比例弁
８ ルーツブロワ
９ 第１の反応筒
９ａ 加熱室
１０ ガスクーラー
１１ モータバルブ
１２ 第２の反応筒
１２ａ 加熱室
１３ ガスクーラー
１４ 背圧調整弁
１７ ＣＯ_２ 分析計[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method and a device for generating an atmosphere gas used for carburizing and quenching applied to parts such as various gears and rolling bearings used for automobile parts and constant velocity joints, and particularly to an atmosphere gas having a high carbon monoxide concentration. And a method and apparatus capable of efficiently generating the same.
[0002]
[Prior art]
In a general gas carburizing treatment, an atmosphere gas containing carbon monoxide and hydrogen is introduced into the inside of a carburizing furnace while heating a material to be treated. Conventionally, the atmosphere gas is produced by converting a hydrocarbon-based gas such as butane, propane, and city gas (13A) and air as raw material gases in a conversion furnace.
[0003]
On the other hand, a method of introducing methanol directly into a heating furnace (a carburizing furnace) without using a shift furnace and using a methanol decomposition gas as an atmospheric gas has also been implemented.
[0004]
Comparison between the conventional method of generating atmospheric gas using a shift furnace (referred to as a shift furnace method) and the method of directly introducing methanol into a heating furnace and using the decomposed gas as an atmosphere gas (referred to as a methanol method) Then, it is known that the carburizing time of the methanol method is shortened by about 20%. This is mainly due to the fact that the CO generated by the shift converter method has a CO concentration of 20 to 23.5%, whereas the methanol decomposition gas can obtain a CO concentration of 33%.
[0005]
That is, in the carburizing process, it the product of the partial pressure of CO and H ₂ partial pressure in the atmospheric gas is large, it is said that the carburizing speed increases carbon transition coefficient becomes higher. Therefore, if the CO concentration in the atmosphere gas is increased, the carburizing time can be shortened and the cost can be reduced.
[0006]
Further, in order to shorten the carburizing time, in recent years, there has been a tendency to increase the carburizing temperature. Conventionally, the carburizing temperature has been from 930 to 950 ° C, but recently, the temperature has been increased to 1050 ° C. Higher carburizing temperatures have not been widespread because of the obstacle of coarsening of the crystal grains of the material to be treated, but this problem is being overcome by advances in steel materials.
[0007]
Various improvements have also been made in the shift converter system. For example, when a hydrocarbon-based gas such as 13A, air and carbon dioxide are mixed by a mixing and feeding device and introduced into the shift converter, the supply amounts of air and / or carbon dioxide A gas carburizing method and an apparatus for variably controlling the CO% in the metamorphic gas by adjusting the temperature have been proposed (see Patent Document 1).
[0008]
[Patent Document 1]
JP-A-2002-35676 (page 2-3, FIG. 1)
[0009]
[Problems to be solved by the invention]
By the way, although the methanol method is effective in shortening the carburizing time because a high CO concentration can be obtained as described above, since methanol is a dangerous substance of the fourth class alcohol specified by the Fire Service Law, Handling volume is regulated. Since heat treatment plants handle a large amount of quenching oil, there is strong resistance to increasing the amount of hazardous materials handled. In some cases, it is not possible to increase the handling amount of dangerous materials in a factory located in an urban area, and in such a case, it is practically impossible to employ the methanol method.
[0010]
Therefore, it is necessary to generate an atmosphere gas having a higher CO concentration by a conventionally used shift furnace method. However, the present inventors modified the conventional shift furnace to convert the gas with oxygen and LPG. Also, the metabolism by carbon dioxide and LPG was tested, but the desired result could not be obtained.
[0011]
Further, if the gas is converted with oxygen and butane gas, theoretically, a gas with a CO of 44% and a H _{2 of} 56% should be obtained as shown in the following equation (1).
C ₄ H ₁₀ + 2O ₂ → 4CO + 5H ₂ +301 kJ (at 1050 ° C.)
[0012]
However, it was found that, when attempting to convert with oxygen and butane gas using a conventional conversion furnace, a large amount of soot was generated and reached a plateau at a CO concentration of around 30%, and did not increase further. The cause is that when oxygen and butane gas are mixed in a stoichiometric ratio and introduced into the shift furnace, a part of the gas introduced near the inlet of the shift furnace causes a combustion reaction as shown in equation (2). This is because the amount of heat is larger than when air is used, so that the butane gas is thermally decomposed before the reforming (reforming) reaction as shown in the equations (3) and (4).
[0013]

[0014]
Since the thermally decomposed butane gas becomes carbon and hydrogen, no reforming reaction occurs and no carbon monoxide is generated.
[0015]
FIG. 3 shows actual measurement results of the temperature distribution in the reaction tube when butane gas was converted into air, oxygen, and carbon dioxide using a conventional shift furnace. The lower side of the figure is the inlet of the raw material gas. In the case of oxygen conversion, the temperature of the inlet is higher than that of normal air conversion. Table 1 shows the gas flow rates when the data of FIG. 3 was obtained, and Table 2 shows the concentration of each component in the gas generated by the reaction. Table 3 shows the state of soot generation in the generated gas.
[0016]
[Table 1]

[0017]
[Table 2]

[0018]
[Table 3]

[0019]
In the case of conversion using carbon dioxide and butane gas (carbon dioxide conversion), it has been found that there is a problem that the temperature at the inlet of the reaction tube is too low, contrary to the conversion of oxygen. Increasing the flow rate ratio of carbon dioxide in the source gas increases the amount of heat absorbed and lowers the temperature. In the case of this metamorphic furnace, 14 m ³ / h is the standard amount of generated gas, but it was not able to generate 10 m ³ / h or more. That is, as can be seen from FIG. 3, the inlet temperature is 777 ° C. at 10 m ³ / h. If the amount of the transformed gas is further increased, the temperature will decrease to 750 ° C. or less. At a temperature between 400 and 750 ° C., the carbon monoxide is decomposed into carbon dioxide and carbon (soot) by the Boudoir reaction shown in equation (5). Therefore, in order to maintain the inlet temperature at 750 ° C. or higher, the amount of the transformed gas cannot be further increased.
2CO → CO ₂ + [C] (5)
[0020]
For this reason, according to the conventional shift furnace method, it is extremely difficult to generate a shift gas having a high CO concentration for a long time without generating soot, despite various proposals.
[0021]
The present invention has been made in view of such circumstances, and uses a shift furnace method to stably and efficiently generate a shift gas having a high CO concentration for a long time without causing blockage due to the generation of soot. And a device suitable for using the method.
[0022]
[Means for Solving the Problems]
In order to achieve the above object, a method for generating a carburizing atmosphere gas of the present invention is a method for generating a carburizing atmosphere gas containing carbon monoxide and hydrogen by reacting a raw material gas containing a hydrocarbon gas. Then, a mixed gas of hydrocarbon gas, carbon dioxide and air is introduced into a furnace under a predetermined mixing ratio, and an exothermic reaction and an endothermic reaction are performed to generate an intermediate metamorphic gas. Atmosphere gas for carburizing is generated by additionally supplying hydrocarbon gas to cause a reforming reaction, and the mixed gas used for the reaction for generating the above-described intermediate metamorphic gas has a temperature of 800 ° C. or higher in the furnace. It is characterized by maintaining a mixing ratio (claim 1).
[0023]
Here, in the method of the present invention, a method of adjusting the additional supply amount of the hydrocarbon gas so that the carbon dioxide concentration is constant in the reforming reaction can be suitably adopted (claim 2).
[0024]
Further, the apparatus for generating a carburizing atmosphere gas of the present invention is an apparatus for generating a carburizing atmosphere gas containing carbon monoxide and hydrogen by reacting a raw material gas containing a hydrocarbon gas. First and second reaction tubes connected in series and each containing a catalyst layer, and a hydrocarbon gas, hydrogen dioxide, and air are supplied to the first reaction tube at a predetermined mixing ratio. Flow rate adjusting means to be introduced, detecting means for detecting the concentration of carbon dioxide in the second reaction cylinder, and flow rate controlling means for automatically adjusting the additional supply amount of the hydrocarbon gas so that the detection result is constant. (Claim 3).
[0025]
In the apparatus of the present invention, the flow rate adjusting means is provided with a first mixing means for mixing two of the three gases of hydrocarbon gas, carbon dioxide and air at a predetermined mixing ratio. It is preferable that the second gas mixing means is constituted by means and a second mixing means for mixing another gas with the mixed gas at a predetermined mixing ratio (claim 4).
[0026]
In the method for generating an atmosphere gas for carburizing according to the present invention, a gas obtained by mixing a hydrocarbon gas, carbon dioxide and air is used as a raw material gas, and the reaction is divided into two stages. Generate gas. In the first-stage reaction, the combustion ratio of the hydrocarbon gas (exothermic reaction exemplified in the above-mentioned formula (2)) is performed without forcibly increasing the CO concentration as a mixing ratio that generates soot. ) And the reforming reaction (endothermic reaction exemplified in the above formulas (3) and (4)), the temperature is maintained at 800 ° C. or higher by keeping the temperature of the heat absorbing zone in the reaction tube at 800 ° C. or more. To reduce soot generation. Then, in the second-stage reaction, a hydrocarbon gas is additionally supplied to the intermediate shift gas to cause a reforming reaction, whereby a carburizing atmosphere gas having a high CO concentration can be generated.
[0027]
In the second-stage reaction, the concentration of carbon dioxide is detected, and the amount of additional supply of hydrocarbon gas is controlled so that the detection result is constant, thereby stabilizing the carburizing atmosphere having a high CO concentration. Gas can be obtained.
[0028]
On the other hand, the apparatus for generating an atmosphere gas for carburizing according to the present invention is an apparatus which facilitates the application of the above-described method of the present invention, and comprises a first and a second step for individually performing the first-stage and second-stage reactions described above. A second reaction tube is provided and connected in series with each other, and the second reaction tube is provided with a means for detecting the concentration of carbon dioxide and a flow rate for controlling an additional supply amount of hydrocarbon gas based on the detection result. It has control means.
[0029]
In the apparatus of the present invention, as the means for adjusting the mixed gas introduced into the first reaction tube, the first means for mixing two of the three kinds of gas used as the raw material and the mixed gas are used. On the other hand, by using the second mixing means for mixing another gas, the mixing ratio of the three gases can be arbitrarily changed under a simple operation. Can also be accurate.
[0030]
In addition, as a suitable hydrocarbon gas used in the present invention, butane gas, LPG, and the like can be given.
[0031]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a system diagram showing a schematic configuration of an embodiment of the present invention.
[0032]
The source gases used for the reaction are butane gas, carbon dioxide and three types of air, of which air is introduced into the first carburetor 2 by an air breather 1 and carbon dioxide is supplied from a carbon dioxide supply source 3 to a pressure proportional valve. 4 and is also introduced into the first carburetor 2 and mixed under a set mixing ratio. The gas mixed by the first carburetor 2 is introduced into the second carburetor 5. A butane gas from a butane gas supply source 6 is introduced into the second carburetor 5 through a pressure proportional valve 7. The second carburetor 5 allows the second carburetor 5 to mix a mixed gas of carbon dioxide and air with a butane gas. Are mixed under the set mixing ratio. Therefore, by adjusting the setting of the mixing ratio of either the first carburetor 2 or the second carburetor 5, the mixing ratio of the three gases can be changed arbitrarily.
[0033]
The mixed gas from the second carburetor 5 is introduced into the first reaction tube 9 via the roots blower 8 from the bottom. The first reaction tube 9 has a nickel catalyst filled therein and is provided in a heating chamber 9a. By the reaction of the mixed gas in the first reaction tube 9, an intermediate metamorphic gas is produced. Generated. The intermediate gas is rapidly cooled by a gas cooler 10 and a top water jacket (not shown) provided at an outlet at the top of the first reaction tube 9. This quenching prevents the generation of soot due to the voodoo reaction of the intermediate metamorphic gas and, at the same time, removes moisture in the gas.
[0034]
The intermediate metamorphic gas from which water has been removed is introduced into the second reaction tube 12 from the bottom together with the butane gas supplied from the butane gas supply source 6 via the motor valve 11. Like the first reaction tube 9, the second reaction tube 12 has a nickel catalyst filled therein and is provided in the heating chamber 12a. In the second reaction tube 12, CO ₂ and H ₂ O contained in the intermediate conversion gas supplied from the first reaction tube 9 are reformed into CO and H ₂ with butane gas as an enriched gas.
[0035]
The gas generated by the second reaction tube 12 is quenched by a top water jacket (not shown) and a gas cooler 13 similarly to the first reaction tube 9, and adjusted to a required pressure by a back pressure adjusting valve 14. Then, it is supplied to the carburizing furnace through the valve 15. The surplus gas is burned by the gas breather 16 and discarded.
[0036]
The supply amount of butane gas to the second reaction tube 12 is determined by measuring the carbon dioxide concentration of the gas generated by the second reaction tube 12 with an infrared CO ₂ analyzer 17 and setting the measurement result of the concentration. This is controlled by automatically adjusting the valve opening of the motor valve 11 so as to maintain the constant value. As a result, the concentration of carbon dioxide in the gas generated by the reforming reaction in the second reaction tube 12 is maintained constant, and the carbon potential is accurately maintained at a desired value.
[0037]
Next, a specific example of actually generating a carburizing atmosphere gas using the above apparatus will be described.
Table 4 shows the flow rate of each gas to the first reaction tube 9, the flow rate of butane gas (enlynch gas) to the second reaction tube 12, and the flow rate of the gas generated in the second reaction tube 12. . [Table 5] shows the concentrations of CO, CO ₂ and CH ₄ in each reaction tube. FIG. 2 shows a temperature distribution in the first reaction tube 9. Then, the state of soot generation in the first and second reaction tubes 9 and 12 is shown in [Table 6]. Since the temperature of the tropical zone in the first reaction tube 9 exceeded 850 ° C., no soot was generated, and it was confirmed that long-term continuous operation was possible.
[0038]
[Table 4]

[0039]
[Table 5]

[0040]
[Table 6]

[0041]
In the above example, the reaction formula in the first reaction cylinder 9 is as shown in the following formula (6). In the equation (6), the concentration in parentheses after each gas after the reaction indicates the concentration.
[0042]

[0043]
The total number of moles of C is 5.05, (CO + CO ₂₎ the amount of _{O 2} (molar number converted) 2.628 total moles 2.83 _{O 2,} the number of moles of the remainder of the _{O 2} 0.200 The remaining number of moles of O was 0.400. The total number of moles of the generated gas is 13.942, and the flow rate of the generated gas is 13.9 m ³ / h.
[0044]
The components after removing water by quenching the gas generated in the first reaction tube 9 are as follows:

The total number of moles is 13.542, and the gas flow rate is 13.5 m ³ / h.
[0045]
The reaction equation in the second reaction tube 12 indicates the concentration of each generated gas together,

Wherein the total number of moles of C is 5.27 and the number of moles of H ₂ newly generated by butane decomposition is 0.270. In addition, the total number of moles of the gas generated at this stage was 14.29, and the flow rate was 14.0 m ³ / h.
[0046]
Heat balance in the reaction described above, the result of calculation with butane 1 m ³ per shown in Table 7.
[0047]
[Table 7]

[0048]
As shown in [Table 7], it became clear that the total heat balance was an exothermic reaction, and the power consumption was extremely small.
[0049]
Note that, in the above example, an example in which butane gas is used as the hydrocarbon gas has been described, but it has been confirmed that the same intended effect can be achieved even with propane gas.
[0050]
【The invention's effect】
According to the present invention, it is possible to stably generate a metamorphic gas having a CO concentration of 35% or more, and to prevent soot from being generated at the time of reaction to block a gas flow path or the like. It is possible.
[0051]
In addition, since the atmosphere gas with high CO concentration can be obtained, the carburizing speed is the same as that of the methanol method even in the shift furnace method, so that high-speed carburizing can be realized even in a factory in an urban area without using a methanol supply facility. can do.
[0052]
Further, in the present invention, the total heat balance can be regarded as an exothermic reaction, and the power consumption can be greatly reduced as compared with the conventional shift furnace. When a comparison was made for the case of the shift furnace with the generated gas amount of 14 m ³ , it was confirmed that the power consumption of the conventional shift furnace was about 8 kW, whereas that of the present invention was about 2 kW when applied.
[Brief description of the drawings]
FIG. 1 is a system diagram showing a schematic configuration of an embodiment of the present invention.
FIG. 2 is a graph showing an actual measurement result of a temperature distribution in a first reaction tube in the embodiment of the present invention.
FIG. 3 is a graph showing actual measurement results of a temperature distribution in a reaction cylinder when butane gas is subjected to air conversion, oxygen conversion, and carbon dioxide conversion using a conventional conversion furnace.
[Explanation of symbols]
Reference Signs List 1 Air breather 2 First carburetor 3 Carbon dioxide supply source 4 Pressure proportional valve 5 Second carburetor 6 Butane gas supply source 7 Pressure proportional valve 8 Roots blower 9 First reaction cylinder 9a Heating chamber 10 Gas cooler 11 Motor valve 12 Second Reaction tube 12a Heating chamber 13 Gas cooler 14 Back pressure regulating valve 17 CO ₂ analyzer

Claims (4)

A method of generating a carburizing atmosphere gas containing carbon monoxide and hydrogen by reacting a source gas containing a hydrocarbon gas,
A mixed gas of hydrocarbon gas, carbon dioxide, and air is introduced into a furnace under a predetermined mixing ratio, and is subjected to an exothermic reaction and an endothermic reaction to generate an intermediate metamorphic gas. While generating an atmosphere gas for carburizing by performing a reforming reaction by additionally supplying
A method for generating a carburizing atmosphere gas, characterized in that the mixed gas used for the reaction for generating the intermediate metamorphic gas has a mixing ratio such that the temperature in the absorption zone in the furnace is maintained at 800 ° C or higher. 2. The method for generating an atmosphere gas for carburizing according to claim 1, wherein in the reforming reaction, an additional supply amount of the hydrocarbon gas is controlled so that a carbon dioxide concentration is constant. 3. An apparatus for generating a carburizing atmosphere gas containing carbon monoxide and hydrogen by reacting a raw material gas containing a hydrocarbon gas,
First and second reaction tubes connected in series and each containing a catalyst layer, and a hydrocarbon gas, carbon dioxide, and air mixed with the first reaction tube at a predetermined mixing ratio. Flow rate adjusting means, a detecting means for detecting the concentration of carbon dioxide in the second reaction cylinder, and a flow rate controlling means for additionally supplying a hydrocarbon gas so that the detection result is constant. An apparatus for generating an atmosphere gas for carburizing characterized by the following. A first mixing unit configured to mix two types of gas out of three types of gases, namely, a hydrocarbon gas, carbon dioxide, and air, at a predetermined mixing ratio; 4. The carburizing atmosphere gas generating apparatus according to claim 3, further comprising a second mixing means for mixing another kind of gas at a predetermined mixing ratio.

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