JPH0512277Y2 - - Google Patents
Info
- Publication number
- JPH0512277Y2 JPH0512277Y2 JP1986061493U JP6149386U JPH0512277Y2 JP H0512277 Y2 JPH0512277 Y2 JP H0512277Y2 JP 1986061493 U JP1986061493 U JP 1986061493U JP 6149386 U JP6149386 U JP 6149386U JP H0512277 Y2 JPH0512277 Y2 JP H0512277Y2
- Authority
- JP
- Japan
- Prior art keywords
- gas
- heat treatment
- outlet
- raw material
- heat
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 239000007789 gas Substances 0.000 claims description 228
- 238000010438 heat treatment Methods 0.000 claims description 168
- 238000000197 pyrolysis Methods 0.000 claims description 57
- 239000002994 raw material Substances 0.000 claims description 49
- 238000004891 communication Methods 0.000 claims description 12
- 239000011261 inert gas Substances 0.000 claims description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 59
- 238000000034 method Methods 0.000 description 32
- 229910052757 nitrogen Inorganic materials 0.000 description 30
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 24
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 22
- 239000000203 mixture Substances 0.000 description 20
- 238000005979 thermal decomposition reaction Methods 0.000 description 18
- 238000005255 carburizing Methods 0.000 description 15
- 229910002092 carbon dioxide Inorganic materials 0.000 description 11
- 239000001569 carbon dioxide Substances 0.000 description 11
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 10
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 9
- 229910000831 Steel Inorganic materials 0.000 description 9
- 239000004071 soot Substances 0.000 description 9
- 239000010959 steel Substances 0.000 description 9
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 8
- 239000000463 material Substances 0.000 description 8
- 239000003054 catalyst Substances 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 6
- 239000003915 liquefied petroleum gas Substances 0.000 description 6
- 229930195733 hydrocarbon Natural products 0.000 description 5
- 150000002430 hydrocarbons Chemical class 0.000 description 5
- 229910052751 metal Inorganic materials 0.000 description 5
- 239000002184 metal Substances 0.000 description 5
- 230000001590 oxidative effect Effects 0.000 description 5
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 4
- 239000004215 Carbon black (E152) Substances 0.000 description 4
- 238000005485 electric heating Methods 0.000 description 4
- 239000001257 hydrogen Substances 0.000 description 4
- 229910052739 hydrogen Inorganic materials 0.000 description 4
- 238000005121 nitriding Methods 0.000 description 4
- 239000001294 propane Substances 0.000 description 4
- 230000005855 radiation Effects 0.000 description 4
- 102200029231 rs11551768 Human genes 0.000 description 4
- 238000011282 treatment Methods 0.000 description 4
- 230000002411 adverse Effects 0.000 description 3
- 239000001273 butane Substances 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
- 238000000354 decomposition reaction Methods 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- IJDNQMDRQITEOD-UHFFFAOYSA-N n-butane Chemical compound CCCC IJDNQMDRQITEOD-UHFFFAOYSA-N 0.000 description 3
- OFBQJSOFQDEBGM-UHFFFAOYSA-N n-pentane Natural products CCCCC OFBQJSOFQDEBGM-UHFFFAOYSA-N 0.000 description 3
- 239000011265 semifinished product Substances 0.000 description 3
- 238000005245 sintering Methods 0.000 description 3
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 229910001315 Tool steel Inorganic materials 0.000 description 2
- LBPGGVGNNLPHBO-UHFFFAOYSA-N [N].OC Chemical compound [N].OC LBPGGVGNNLPHBO-UHFFFAOYSA-N 0.000 description 2
- 229910021529 ammonia Inorganic materials 0.000 description 2
- 238000005219 brazing Methods 0.000 description 2
- 238000005256 carbonitriding Methods 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 150000002431 hydrogen Chemical class 0.000 description 2
- 238000012423 maintenance Methods 0.000 description 2
- 239000007769 metal material Substances 0.000 description 2
- 230000002829 reductive effect Effects 0.000 description 2
- 230000000717 retained effect Effects 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 230000009466 transformation Effects 0.000 description 2
- 229910000851 Alloy steel Inorganic materials 0.000 description 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- 229910001018 Cast iron Inorganic materials 0.000 description 1
- 229910001208 Crucible steel Inorganic materials 0.000 description 1
- XBDQKXXYIPTUBI-UHFFFAOYSA-M Propionate Chemical compound CCC([O-])=O XBDQKXXYIPTUBI-UHFFFAOYSA-M 0.000 description 1
- 229910000746 Structural steel Inorganic materials 0.000 description 1
- KXKVLQRXCPHEJC-UHFFFAOYSA-N acetic acid trimethyl ester Natural products COC(C)=O KXKVLQRXCPHEJC-UHFFFAOYSA-N 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 239000003570 air Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 238000009529 body temperature measurement Methods 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 239000010962 carbon steel Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 239000002826 coolant Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 238000007791 dehumidification Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 150000002829 nitrogen Chemical class 0.000 description 1
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- BDERNNFJNOPAEC-UHFFFAOYSA-N propan-1-ol Chemical compound CCCO BDERNNFJNOPAEC-UHFFFAOYSA-N 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- 230000000171 quenching effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000002441 reversible effect Effects 0.000 description 1
- 229910052703 rhodium Inorganic materials 0.000 description 1
- 239000010948 rhodium Substances 0.000 description 1
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 238000005496 tempering Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Landscapes
- Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
Description
産業上の利用分野
本考案は、窒素などの不活性ガスをベースとす
るガス雰囲気下に金属材料、半製品等の被処理体
の熱処理を行うための熱処理炉に関するものであ
る。
従来の技術
〈熱処理、その種類、雰囲気ガス〉
金属材料、半製品等に所望の性質を与えるため
の熱的操作を金属の熱処理と言う。金属の熱処理
により、金属加工の際に起こる結晶の歪みの修
正、金属中の炭素や珪素の量や配列の変更がなさ
れる結果、金属が強靱性を有するようになつた
り、美麗仕上げがなされる。
熱処理の種類としては、焼なまし、焼入れ、焼
もどし、浸炭、浸炭窒化、窒化、軟窒化、鑞付
け、焼結、焼ならし、光輝熱処理などがあげられ
る。
このような熱処理に際して用いられる雰囲気ガ
スとして、従来より、この業界では周知のRXガ
ス、DXガス、NXガス、HNXガス、AXガスと
呼ばれるガスをはじめとする種々の組成のガスが
使用されている。たとえばRXガスは、一酸化炭
素22〜25％、水素32〜34％、窒素残部の比率を持
つガスであり、無酸化焼入れ、浸炭、焼結などに
際しての雰囲気ガスとして広く用いられている。
〈変成炉を用いる方式〉
雰囲気ガスの製造し熱処理炉へ供給する方式と
しては、熱処理炉とは別個の触媒充填変成炉にメ
タン、プロパン、ブタンなどの炭化水素系ガスと
空気との混合物またはアンモニアガスを供給し、
該変成炉で触媒と接触させて所望のガス組成とな
し、このガスを常温近くにまで冷却した後、目的
によつては炭酸ガスを除去して、熱処理炉に送る
方式が現在最も一般的となつている。
この変成炉方式によれば、たとえばRXガス
は、プロパンやブタンに空気を混入した原料ガス
をニツケル系やロジウム系などの触媒を充填した
変成炉に供給して約1150℃で変成分解することに
より得られる。
変成炉で生成したガスは、上述のように一旦常
温近くまで冷却するのが通例であるが、上記ガス
を熱処理炉に供給する管路に熱交換器を設け、こ
の熱交換器において水、油などの冷却剤との間で
熱交換を行つて所定の温度まで冷却（ただし700
℃以上に保つように）することにより、変成炉で
生成したガスを700℃以上に保つたまま熱処理炉
に供給する方式が提案されている。（たとえば特
開昭50−130609号公報）
また、変成炉で生成した高温のガスを、まず熱
処理炉内に設けられた放熱管内を通すことにより
熱処理炉内の雰囲気にその保有熱を与え、ついで
冷却、脱湿、成分調節等を行つた後、必要に応じ
前記高温のガスと熱交換させてから、熱処理炉内
に導入して雰囲気ガスを形成する方法も提案され
ている。（たとえば特公昭39−27991号公報）
〈変成炉を使用しない方式〉
変成炉を使用しない方式の一つとして、特公昭
48−34085号公報には、熱処理炉内に内管と外管
とからなる二重構造の電熱管を配置し、電熱管の
うち内管の一端から液化石油ガスと空気との混合
物を供給して内管内で熱分解させ、熱分解したガ
スを内管の他端から熱処理炉内に送り込み、一方
電熱管のうち外管により熱処理炉内を加熱する方
式が示されている。
変成炉を使用しない方式として、最近では、窒
素などの不活性ガスにメタノール、プロパン、液
化石油ガスなどを混合した熱処理雰囲気原料ガス
（以下「原料ガス」と略す）を直接熱処理炉に供
給して炉内で熱分解を行い、雰囲気ガスとするい
わゆる窒素ベース熱処理法が注目されている。
この窒素ベース熱処理法は、変成炉および触媒
が不要になることから初期投資、電力消費、設備
保全、設置面積・容積の点で有利であり、また窒
素ベースであるため安全性にすぐれ、夜間の無人
操業が簡単であつたり、熱処理炉の立ち上がりが
速く、操作性、作業生が向上することなどの点で
も有利である。窒素ベース熱処理法では吸着分離
方法による窒素、たとえばいわゆるPSA方式に
より得られる安価な窒素を使用できるので、その
運転経費は充填法と同等となり、さらに上述のよ
うな有利さがあるので、将来大変有望視されてい
る技術である。
考案が解決しようとする問題点
上記中変成炉を用いる方式は、従来より広く採
用されているが、変成炉およびそれに充填する触
媒の使用を必須とするため、初期投資、設備保全
などの点で不利であり、また変成炉は馴し運転
（エージング）が必要である。
これに対し窒素ベース熱処理法は、前述のよう
な利点を有するのでその将来生が期待されている
が、この方法も次に列挙するような問題点を残し
ている。
熱処理の雰囲気ガスの組成は炉温度に関係な
く常に一定でなければならないが、窒素ベース
熱処理法を採用した場合は熱処理炉の温度が変
化するとそれに応じてガス組成が変動するた
め、熱処理に悪影響を及ぼす。たとえば浸炭熱
処理の場合、浸炭の活性炭素濃度、深さが不均
一になりやすい。
熱処理温度が低くなると煤（スス）が発生す
るおそれがあり、特に窒素−メタノール、窒素
−液化石油ガスの場合には煤が発生しやすく、
普及の障害となつている。
軟窒化処理については、この処理が550〜600
℃という比較的低温で行う熱処理であるため、
窒素ベース熱処理法では分解が不充分で、従つ
て窒素ベース熱処理法は軟窒化処理には適用で
きない。
熱処理温度が低い場合、熱分解が完全には進
まないため熱分解ガスの発生量が少なく、従つ
て供給する原料ガスの量が多くなつて資源の浪
費を招き、原価的にも不利になる。
また変成炉を使用しない方式の一つとして先に
あげた特公昭48−34085号公報の技術は、原料ガ
ス（液化石油ガスと空気との混合物）の加熱を専
ら電熱管（内管）のみにより行うものであるた
め、熱処理炉の炉内温度が熱分解には有効利用さ
れないこと、原料ガスが内管内を通過する短時間
の間に熱分解を完了しなければならないため、電
気エネルギーの消費が多くなり、また熱分解不足
を生ずるおそれがあることなどの問題点がある。
そのため、この方法を窒素ベース熱処理法に適用
しようとしても、実用化までは期待できるもので
はない。
本考案は、窒素ベース熱処理法を採用しながら
も、窒素ベース熱処理法の持つ上述のような問題
点を解消することを目的に鋭意研究を重ねた結果
到達したものである。
問題点を解決するための手段
本考案の熱処理炉は、不活性ガスをベースとす
るガス雰囲気下に被処理体の熱処理を行うための
熱処理炉において、
熱処理室１の外部に熱分解室５を設けること、
該熱分解室５は、最外筒２、外筒３および内筒
４からなる三重筒の形状を有し、かつ熱処理雰囲
気原料ガスと排ガスとの間で熱交換する熱交換器
の構造を有し、さらに加熱手段１４を備えている
こと、
上記熱分解室５の最外筒２には排ガス入口６と
排ガス出口７とを設けて最外筒２と外筒３との間
〓部８を排ガス流路となすこと、
上記熱分解室５の外筒３には第１ガス出入口Ａ
を、内筒４には第２ガス出入口Ｂを、さらに、内
筒４には内外筒間〓部１２との連通口１１を設
け、
［イ］ 第１ガス出入口Ａを熱処理雰囲気原料ガ
ス供給系１９と接続して原料ガス供給口９とし
て用い、一方第２ガス出入口Ｂを熱処理室ガス
供給口と接続して熱分解ガス導出口１０として
用いるか、あるいは、
［ロ］ 第２ガス出入口Ｂを熱処理雰囲気原料ガ
ス供給系１９と接続して原料ガス供給口９とし
て用い、一方第１ガス出入口Ａを熱処理室ガス
供給口と接続して熱分解ガス導出口１０として
用いること、
上記加熱手段１４は、熱分解室５内部の内外筒
間〓部１２、連通口１１、内筒内部空間１３を繋
ぐガス流路を熱処理雰囲気原料ガスが流通する間
に該ガスを熱分解するために、内筒内部空間１３
内に設置すること、
を特徴とするものである。
本考案において用いられる原料ガスとしては、
不活性ガス（通常は窒素、場合によりアルゴン、
ヘリウム）をベースとし、熱処理の目的によつて
還元性ガス（水素など）、浸炭性ガス、液（メタ
ン、プロパン、ブタン、メタノール、プロパノー
ル、酢酸メチル、液化石油ガス、アセトンなど）
を添加したものが用いられる。具体例のいくつか
を以下に列挙する。
１ 光輝熱処理、鑞付け、焼結雰囲気ガス
窒素＋水素
完全光輝熱処理
窒素＋水素＋炭化水素
非脱炭光輝熱処理
窒素＋メタノール
非脱炭光輝熱処理
２ 浸炭、浸炭窒化雰囲気ガス
窒素＋炭化水素
浸炭熱処理
窒素＋メタノール＋炭化水素
浸炭熱処理
窒素＋メタノール＋炭化水素＋アンモニア
浸炭、窒化熱処理
熱処理炉はバツチ式の炉であつても、連続式の
炉であつてもよい。連続式の場合、熱処理室１は
たとえば昇温帯域、浸炭帯域、拡散帯域および降
温帯域からなるが、本考案における熱分解室５か
ら導出される熱分解ガスは、これらの帯域のうち
任意の１ないし２以上の帯域に送り込むことがで
きる。
熱処理室１の熱源は、燃焼加熱、電気的加熱の
いずれであつてもよく、また加熱方式も直接加熱
方式、間接加熱方式の如何を問わない。
排ガスとしては、熱源となりうる適当な排ガス
がある場合にはその排ガスを適宜使用することが
できるが、熱処理室１をガスで加熱する型の熱処
理室とするときは、排ガスとして、たとえば熱処
理室１内にしばしば設置し管内でガスを燃焼し高
温となつた管の輻射熱で加熱を行う輻射管型バー
ナ（ラジアントチユーブ型バーナ）１５から排ガ
スを用いるのが最も実用的であり、そのほか場合
により熱処理室１内の高温の雰囲気ガスを排出し
たときの排ガスを用いることもできる。
熱処理室１の外部に設ける熱分解室５の構成に
ついては、後の実施例で詳述する。なお熱分解室
５の内筒内部空間１３には、排ガスの保有する熱
量のみによつては不足することのある熱量を補償
するため、加熱手段１４を配置する。
加熱手段１４としては、電熱線加熱器、高周波
加熱器、赤外線加熱器、熱媒により加熱する熱交
換器、輻射管型バーナ等を必要に応じ適宜選択し
て用いればよいが、本考案における加熱手段１４
がここに例示した加熱手段によつて限定されるも
のではないことはもちろんである。
被処理体としては、溶接構造用鋼、機械構造用
炭素鋼、機械構造用合金鋼、ステンレス鋼、炭素
工具鋼、合金工具鋼、特殊用途鋼、鋳鉄、鋳鋼、
鍛鋼などの各種材料やそれらから造られた半製品
等があげられる。
作 用
窒素などの不活性ガスをベースとし、これに還
元性ガス、浸炭性ガス、液などを混入した原料ガ
スを熱処理雰囲気原料ガス供給系１９から原料ガ
ス供給口９を経て熱分解室５に供給し、内外筒間
〓部１２、連通口１１、および内筒内部空間１３
を経て（あるいは、内筒内部空間１３、連通口１
１、内外筒間〓部１２を経て）、熱分解ガス導出
口１０から導出し、熱処理室１内に送り込む。そ
してその間に、排ガス入口６から導入し最外筒２
と外筒３との間〓部８を経て排ガス出口７から導
出する排ガスとの間の熱交換により原料ガスを熱
分解する。内筒内部空間１３に加熱手段１４を設
けることにより、不足する熱量を補償する。
上記の熱分解により所定の組成となつたガスを
熱処理室１の内部空間に送り込み、被処理体をこ
の雰囲気ガスの下に熱処理する。
もし熱分解室５内で煤が発生したときは、空気
供給系２０から空気を送り込むことにより、熱分
解室５内の煤を燃焼によつて除去できる。
窒素ガスをベースとし、これにそれぞれメタノ
ール、メタン、メタンと二酸化炭素、メタンと水
を混入して熱分解室５に供給したときの熱分解反
応は、主として次式の左辺の物質から右辺の物質
が生成する反応によるものと推定される。
N2＋CH3OH→N2＋H2＋CO＋CH4＋CO2＋H2Ｏ
N2＋CH4→N2＋H2＋Ｃ＋CH4
N2＋CH4＋CO2→N2＋H2＋CO＋CH4＋CO2＋H2
Ｏ
N2＋CH4＋H2Ｏ→N2＋H2＋CO＋CH4＋CO2＋
H2Ｏ
実施例
次に実施例をあげて本考案の熱処理炉をさらに
説明する。
実施例 １
第１図は、本考案の熱処理炉の一例を示した断
面説明図である。
１は熱処理室であり、１６はその外壁である。
１５は熱処理室１内を所定の温度に加熱するため
の輻射管型バーナ、１７は炉内の雰囲気を攪拌ま
たは循環するためのフアン、１８はエジエクタ
ー、２１は被処理体である。
５は熱分解室であり、最外筒２、外筒３および
内筒４を設置した三重筒の形状を有する。
６は排ガス入口であり、最外筒２の側部下側に
設けてある。７は排ガス出口であり、最外筒２の
頂部に設けてある。そして最外筒２と外筒３との
間〓部８が排ガス流路を形成している。
熱処理室１の輻射管型バーナ１５からエジエク
ター１８を経て排ガス入口６から間〓部８に導入
された排ガスを排ガス出口７から排出する。
Ａは外筒３の下端に設けた第１ガス出入口であ
り、本実施例においてはこれを熱分解ガス導出口
１０として用いた。
１１は内筒４の頂部に設けた連通口であり、Ｂ
は内筒４の下端に設けた第２ガス出入口であり、
本実施例においてはこれを原料ガス供給口９とし
て用いた。
１２は内外筒間〓部、１３は内筒内部空間であ
る。
内筒内部空間１３に配置した加熱手段１４とし
ては、熱処理室１内の高温の雰囲気ガスを排出し
たときの排ガスの保有する熱を利用するための熱
交換器を用いた。
１９は熱処理雰囲気原料ガス供給系であり、窒
素などの不活性ガスをベースとし、これに適当な
ガスまたは液を混入した原料ガスが前記の原料ガ
ス供給口９に供給できるように配管してある。
２０は、熱分解室５内に煤が付着したとき、そ
の煤を燃焼除去するための空気供給系である。
このように構成することにより、原料ガス供給
口９から供給された原料ガスを、内筒内部空間１
３、連通口１１、内外筒間〓部１２を通過させる
間に熱分解し、熱分解ガス導出口１０から熱処理
室１に送り込んだ。
第１図に示した熱処理炉を用いてRX相当雰囲
気ガスによる鉄鋼材の浸炭処理を行うべく、熱分
解室５に窒素55vol％およびメタノール45vol％よ
りなる原料ガスを供給して、種々の温度における
熱分解ガス（すなわち雰囲気ガス）の発生を試み
た。このときの熱分解ガスの組成を第１表に示
す。
INDUSTRIAL APPLICATION FIELD The present invention relates to a heat treatment furnace for heat treating objects to be treated, such as metal materials and semi-finished products, in a gas atmosphere based on an inert gas such as nitrogen. BACKGROUND TECHNOLOGY (Heat treatment, its types, atmospheric gas) Thermal operations for imparting desired properties to metal materials, semi-finished products, etc. are called heat treatment of metals. Heat treatment of metal corrects crystal distortions that occur during metal processing and changes the amount and arrangement of carbon and silicon in the metal, making the metal tougher and giving it a beautiful finish. . Types of heat treatment include annealing, hardening, tempering, carburizing, carbonitriding, nitriding, soft nitriding, brazing, sintering, normalizing, bright heat treatment, and the like. Conventionally, gases of various compositions have been used as atmospheric gases used in such heat treatments, including gases known in the industry as RX gas, DX gas, NX gas, HNX gas, and AX gas. . For example, RX gas is a gas with a ratio of 22 to 25% carbon monoxide, 32 to 34% hydrogen, and the balance nitrogen, and is widely used as an atmospheric gas in non-oxidizing quenching, carburizing, sintering, etc. <Method using a shift furnace> As a method of producing atmospheric gas and supplying it to the heat treatment furnace, a mixture of hydrocarbon gases such as methane, propane, butane, and air or ammonia is supplied to a catalyst-filled shift furnace separate from the heat treatment furnace. supply gas,
Currently, the most common method is to bring the gas into contact with a catalyst in the conversion furnace to achieve the desired gas composition, cool this gas to near room temperature, remove carbon dioxide depending on the purpose, and send it to a heat treatment furnace. It's summery. According to this shift furnace system, RX gas, for example, is produced by supplying raw material gas such as propane or butane with air to a shift furnace filled with a nickel-based or rhodium-based catalyst, and decomposing it at approximately 1150°C. can get. As mentioned above, the gas generated in the conversion furnace is normally cooled to near normal temperature, but a heat exchanger is installed in the pipe line that supplies the gas to the heat treatment furnace, and this heat exchanger cools the gas to near room temperature. It cools down to a specified temperature by exchanging heat with a coolant such as (however, 700
A method has been proposed in which the gas generated in the shift furnace is maintained at 700°C or higher and then supplied to the heat treatment furnace. (For example, Japanese Patent Application Laid-Open No. 130609/1983) Also, the high temperature gas generated in the conversion furnace is first passed through a heat radiation tube installed in the heat treatment furnace to give its retained heat to the atmosphere inside the heat treatment furnace, and then A method has also been proposed in which after cooling, dehumidification, component adjustment, etc., the gas is exchanged with the high-temperature gas as necessary, and then introduced into a heat treatment furnace to form an atmospheric gas. (For example, Japanese Patent Publication No. 39-27991) <Method that does not use a transformation furnace> As a method that does not use a transformation furnace,
Publication No. 48-34085 discloses that a double-structure electric heating tube consisting of an inner tube and an outer tube is arranged in a heat treatment furnace, and a mixture of liquefied petroleum gas and air is supplied from one end of the inner tube of the electric heating tube. In this method, the gas is thermally decomposed in the inner tube, and the thermally decomposed gas is sent into the heat treatment furnace from the other end of the inner tube, while the inside of the heat treatment furnace is heated by the outer tube of the electric heating tube. Recently, as a method that does not use a shift furnace, a heat treatment atmosphere raw gas (hereinafter referred to as "raw material gas"), which is a mixture of inert gas such as nitrogen and methanol, propane, liquefied petroleum gas, etc., is supplied directly to the heat treatment furnace. A so-called nitrogen-based heat treatment method that performs thermal decomposition in a furnace and uses atmospheric gas is attracting attention. This nitrogen-based heat treatment method is advantageous in terms of initial investment, power consumption, equipment maintenance, and installation space and volume because it eliminates the need for a conversion furnace and catalyst.Also, since it is nitrogen-based, it is highly safe and can be used at night. It is also advantageous in that unmanned operation is easy, the heat treatment furnace can be started up quickly, and operability and work efficiency are improved. Since the nitrogen-based heat treatment method allows the use of nitrogen produced by adsorption separation methods, for example the inexpensive nitrogen obtained by the so-called PSA method, its operating costs are comparable to those of the filling method, and it also has the advantages mentioned above, making it very promising in the future. It is a technology that is widely regarded. Problems that the invention aims to solve The above method using a medium-sized converter has been widely adopted, but since it requires the use of a converter and a catalyst to fill it, it has problems in terms of initial investment, equipment maintenance, etc. This is a disadvantage, and the converter requires aging. On the other hand, the nitrogen-based heat treatment method has the above-mentioned advantages and is expected to be used in the future, but this method also has the following problems. The composition of the atmospheric gas for heat treatment must always be constant regardless of the furnace temperature, but when a nitrogen-based heat treatment method is adopted, the gas composition changes accordingly when the temperature of the heat treatment furnace changes, which can adversely affect heat treatment. affect For example, in the case of carburizing heat treatment, the activated carbon concentration and depth of carburization tend to be uneven. If the heat treatment temperature is low, soot may be generated, and soot is particularly likely to be generated when using nitrogen-methanol or nitrogen-liquefied petroleum gas.
This is becoming an obstacle to its widespread use. Regarding nitrocarburizing treatment, this treatment is 550 to 600
Because the heat treatment is performed at a relatively low temperature of °C,
Nitrogen-based heat treatment methods provide insufficient decomposition, and therefore nitrogen-based heat treatment methods cannot be applied to soft-nitriding treatments. When the heat treatment temperature is low, thermal decomposition does not proceed completely, so the amount of pyrolysis gas generated is small, and therefore the amount of raw material gas to be supplied increases, leading to waste of resources and being disadvantageous in terms of cost. Furthermore, the technology disclosed in Japanese Patent Publication No. 48-34085 mentioned earlier as a method that does not use a conversion furnace heats the raw material gas (a mixture of liquefied petroleum gas and air) exclusively using electric heating tubes (inner tubes). Because the temperature inside the heat treatment furnace is not effectively used for pyrolysis, and the pyrolysis must be completed within a short time while the raw material gas passes through the inner tube, electrical energy consumption is reduced. There are also problems such as the possibility of insufficient thermal decomposition.
Therefore, even if this method is applied to a nitrogen-based heat treatment method, it cannot be expected to be put to practical use. The present invention was arrived at as a result of intensive research aimed at solving the above-mentioned problems of the nitrogen-based heat treatment method while employing the nitrogen-based heat treatment method. Means for Solving the Problems The heat treatment furnace of the present invention is a heat treatment furnace for heat treating objects to be treated in an inert gas-based gas atmosphere, and includes a pyrolysis chamber 5 outside the heat treatment chamber 1. The pyrolysis chamber 5 has a triple cylinder shape consisting of an outermost cylinder 2, an outer cylinder 3, and an inner cylinder 4, and is equipped with a heat exchanger for exchanging heat between the raw material gas and the exhaust gas in the heat treatment atmosphere. The outermost cylinder 2 of the pyrolysis chamber 5 is provided with an exhaust gas inlet 6 and an exhaust gas outlet 7 between the outermost cylinder 2 and the outer cylinder 3. The outer cylinder 3 of the pyrolysis chamber 5 is provided with a first gas inlet/outlet A.
, the inner cylinder 4 is provided with a second gas inlet/outlet B, and the inner cylinder 4 is further provided with a communication port 11 with the inner/outer cylinder inter-cylinder part 12; 19 and used as the raw material gas supply port 9, while the second gas inlet/outlet B is connected to the heat treatment chamber gas supply port and used as the pyrolysis gas outlet 10, or [b] the second gas inlet/outlet B is The heating means 14 is connected to a heat treatment atmosphere raw material gas supply system 19 and used as a raw material gas supply port 9, while the first gas inlet/outlet A is connected to a heat treatment chamber gas supply port and used as a pyrolysis gas outlet 10. , inside the inner cylinder in order to thermally decompose the gas while the raw material gas flows through the gas flow path connecting the inner and outer cylinder part 12, the communication port 11, and the inner cylinder internal space 13 inside the thermal decomposition chamber 5. space 13
It is characterized by the fact that it can be installed within the The raw material gas used in this invention is as follows:
Inert gas (usually nitrogen, sometimes argon,
depending on the purpose of heat treatment, reducing gases (hydrogen, etc.), carburizing gases, liquids (methane, propane, butane, methanol, propanol, methyl acetate, liquefied petroleum gas, acetone, etc.)
is used. Some specific examples are listed below. 1 Bright heat treatment, brazing, sintering atmosphere gas Nitrogen + hydrogen Complete bright heat treatment Nitrogen + hydrogen + hydrocarbons Non-decarburizing bright heat treatment Nitrogen + methanol Non-decarburizing bright heat treatment 2 Carburizing, carbonitriding atmosphere gas Nitrogen + hydrocarbon Carburizing heat treatment Nitrogen + Methanol + Hydrocarbon Carburizing heat treatment Nitrogen + Methanol + Hydrocarbon + Ammonia Carburizing, nitriding heat treatment The heat treatment furnace may be a batch type furnace or a continuous type furnace. In the case of a continuous type, the heat treatment chamber 1 is composed of, for example, a temperature increasing zone, a carburizing zone, a diffusion zone, and a temperature decreasing zone, but the pyrolysis gas derived from the pyrolysis chamber 5 in the present invention can be used in any one of these zones. or can be sent to two or more bands. The heat source of the heat treatment chamber 1 may be either combustion heating or electrical heating, and the heating method may be a direct heating method or an indirect heating method. As the exhaust gas, if there is a suitable exhaust gas that can serve as a heat source, that exhaust gas can be used as appropriate; however, when the heat treatment chamber 1 is a type of heat treatment chamber heated with gas, for example, The most practical method is to use exhaust gas from a radiant tube burner (radiant tube burner) 15, which is often installed inside the tube and burns gas inside the tube to heat the tube using the radiant heat of the tube. It is also possible to use exhaust gas when the high-temperature atmospheric gas in 1 is discharged. The structure of the pyrolysis chamber 5 provided outside the heat treatment chamber 1 will be described in detail in later examples. Note that a heating means 14 is disposed in the inner cylinder space 13 of the pyrolysis chamber 5 in order to compensate for the amount of heat that may be insufficient depending only on the amount of heat held by the exhaust gas. As the heating means 14, a heating wire heater, a high-frequency heater, an infrared heater, a heat exchanger heating with a heat medium, a radiation tube burner, etc. may be selected and used as necessary, but the heating means in the present invention Means 14
Of course, it is not limited to the heating means illustrated here. Objects to be treated include welded structural steel, mechanical structural carbon steel, mechanical structural alloy steel, stainless steel, carbon tool steel, alloy tool steel, special purpose steel, cast iron, cast steel,
Examples include various materials such as forged steel and semi-finished products made from them. Function A raw material gas based on an inert gas such as nitrogen and mixed with reducing gas, carburizing gas, liquid, etc. is supplied to the thermal decomposition chamber 5 from the heat treatment atmosphere raw gas supply system 19 through the raw gas supply port 9. between the inner and outer cylinders 12, the communication port 11, and the inner cylinder internal space 13.
(or the inner cylinder internal space 13, the communication port 1
1. The pyrolysis gas is led out from the outlet 10 (via the inner and outer cylinder section 12) and sent into the heat treatment chamber 1. During that time, the exhaust gas is introduced from the inlet 6 into the outermost cylinder 2.
The raw material gas is thermally decomposed by heat exchange between the outer cylinder 3 and the exhaust gas led out from the exhaust gas outlet 7 via the bottom part 8. By providing the heating means 14 in the inner cylinder internal space 13, the insufficient amount of heat is compensated for. The gas having a predetermined composition due to the above thermal decomposition is sent into the internal space of the heat treatment chamber 1, and the object to be treated is heat treated under this atmospheric gas. If soot is generated in the pyrolysis chamber 5, the soot in the pyrolysis chamber 5 can be removed by combustion by feeding air from the air supply system 20. When nitrogen gas is used as a base and methanol, methane, methane and carbon dioxide, and methane and water are mixed and supplied to the thermal decomposition chamber 5, the thermal decomposition reaction mainly changes from the substance on the left side to the substance on the right side of the following equation. It is presumed that this is due to the reaction that generates. N 2 +CH 3 OH→N 2 +H 2 +CO+CH 4 +CO 2 +H 2 O N 2 +CH 4 →N 2 +H 2 +C+CH 4 N 2 +CH 4 +CO 2 →N 2 +H 2 +CO+CH 4 +CO 2 +H 2
O N 2 +CH 4 +H 2 O→N 2 +H 2 +CO+CH 4 +CO 2 +
H 2 O Examples Next, the heat treatment furnace of the present invention will be further explained with reference to examples. Example 1 FIG. 1 is a cross-sectional explanatory diagram showing an example of a heat treatment furnace of the present invention. 1 is a heat treatment chamber, and 16 is its outer wall.
15 is a radiation tube burner for heating the inside of the heat treatment chamber 1 to a predetermined temperature, 17 is a fan for stirring or circulating the atmosphere in the furnace, 18 is an ejector, and 21 is an object to be processed. 5 is a pyrolysis chamber, which has the shape of a triple cylinder in which an outermost cylinder 2, an outer cylinder 3, and an inner cylinder 4 are installed. Reference numeral 6 denotes an exhaust gas inlet, which is provided at the lower side of the outermost cylinder 2. 7 is an exhaust gas outlet, which is provided at the top of the outermost cylinder 2. A bottom portion 8 between the outermost cylinder 2 and the outer cylinder 3 forms an exhaust gas flow path. The exhaust gas introduced from the radiant tube burner 15 of the heat treatment chamber 1 through the ejector 18 to the exhaust gas inlet 6 into the intermediate part 8 is discharged from the exhaust gas outlet 7. A is a first gas inlet/outlet provided at the lower end of the outer cylinder 3, and this was used as the pyrolysis gas outlet 10 in this example. 11 is a communication port provided at the top of the inner cylinder 4;
is a second gas inlet/outlet provided at the lower end of the inner cylinder 4,
In this example, this was used as the raw material gas supply port 9. 12 is a portion between the inner and outer cylinders, and 13 is an internal space of the inner cylinder. As the heating means 14 disposed in the inner cylinder internal space 13, a heat exchanger was used to utilize the heat retained in the exhaust gas when the high-temperature atmospheric gas in the heat treatment chamber 1 was discharged. Reference numeral 19 denotes a heat treatment atmosphere raw material gas supply system, which is piped so that raw material gas, which is based on an inert gas such as nitrogen and mixed with an appropriate gas or liquid, can be supplied to the raw material gas supply port 9. . Reference numeral 20 denotes an air supply system for burning and removing soot when it adheres to the inside of the pyrolysis chamber 5. With this configuration, the raw material gas supplied from the raw material gas supply port 9 is transferred to the inner cylinder internal space 1.
3. The gas was thermally decomposed while passing through the communication port 11 and the inner/outer cylinder inter-cylinder part 12, and was sent into the heat treatment chamber 1 through the thermal decomposition gas outlet 10. In order to carburize steel materials using an atmospheric gas equivalent to RX using the heat treatment furnace shown in Fig. 1, a raw material gas consisting of 55 vol% nitrogen and 45 vol% methanol was supplied to the pyrolysis chamber 5, and carburization was performed at various temperatures. An attempt was made to generate pyrolysis gas (ie, atmospheric gas). The composition of the pyrolysis gas at this time is shown in Table 1.
【表】
また、上記において熱処理温度を850℃に設定
し、被処理体として鉄鋼材（JIS S15C、
SCM415、SCr415）を用いて浸炭を行つた後の
品質を第２表に示す。[Table] In addition, in the above, the heat treatment temperature was set at 850℃, and the object to be treated was steel material (JIS S15C,
Table 2 shows the quality after carburizing using SCM415, SCr415).
【表】
硬度の標準偏差は、S15Cの場合が0.431、
SCM415の場合が0.410、SCr415の場合が0.443で
ある。
なお参考のため、従来のRXガスを用いて浸炭
を行つた場合を第２表に［ ］で示す。
実施例 ２
実施例１で用いた熱処理炉において、熱分解室
５内のガスの流れを逆にする。
すなわち、外筒３に設けた第１ガス出入口Ａを
原料ガス供給口９として用い、内筒４に設けた第
２ガス出入口Ｂを熱分解ガス導出口１０として用
いる如く改装した熱処理炉を用いて、実施例１と
同一組成の原料ガスを第１ガス出入口Ａから供給
し、内外筒間〓部１２、連通口１１、内筒内部空
間１３を経て第２ガス出入口Ｂから熱処理室１へ
送り込んで、実施例１と同じ熱処理温度で鉄鋼材
の浸炭を行つた。
その結果、熱分解ガスの組成、浸炭後の品質と
もに実施例１の場合とほぼ同一の成績を得た。
比較例 １
熱分解室５を設けることなく、従来の窒素ベー
ス熱処理法に従つて実験を行つた。種々の熱処理
温度における熱分解ガス（すなわち雰囲気ガス）
の組成を第３表に示す。[Table] The standard deviation of hardness is 0.431 for S15C,
The value is 0.410 for SCM415 and 0.443 for SCr415. For reference, Table 2 shows cases in which carburizing was performed using conventional RX gas. Example 2 In the heat treatment furnace used in Example 1, the flow of gas in the pyrolysis chamber 5 is reversed. That is, using a heat treatment furnace that has been renovated so that the first gas inlet/outlet A provided in the outer cylinder 3 is used as the raw material gas supply port 9, and the second gas inlet/outlet B provided in the inner cylinder 4 is used as the pyrolysis gas outlet 10. , a raw material gas having the same composition as in Example 1 was supplied from the first gas inlet/outlet A, and sent into the heat treatment chamber 1 from the second gas inlet/outlet B via the inner and outer cylinder inter-cylinder part 12, the communication port 11, and the inner cylinder internal space 13. The steel material was carburized at the same heat treatment temperature as in Example 1. As a result, the composition of the pyrolysis gas and the quality after carburization were almost the same as in Example 1. Comparative Example 1 An experiment was conducted according to a conventional nitrogen-based heat treatment method without providing a pyrolysis chamber 5. Pyrolysis gas (i.e. atmospheric gas) at various heat treatment temperatures
The composition of is shown in Table 3.
【表】
また、上記において熱処理温度を850℃に設定
し、被処理体として鉄鋼材（JIS S15C、
SCM415、SCr415）を用いて浸炭を行つた後の
品質を第４表に示す。[Table] In addition, in the above, the heat treatment temperature was set at 850℃, and the object to be treated was steel material (JIS S15C,
Table 4 shows the quality after carburizing using SCM415, SCr415).
【表】
硬度の標準偏差は、S15Cの場合が0.493、
SCM415の場合が0.465、SCr415の場合が0.501で
ある。
なお参考のため、従来のRXガスを用いて浸炭
を行つた場合を第４表に［ ］で示す。
第１表と第３表との比較から、次のことがわか
る。
まず通常の窒素ベース熱処理法による比較例１
においては、熱処理温度によつて原料ガスの熱分
解挙動が異なるため、熱処理温度が変わると組成
がかなり変動し、しかも微量成分である炭酸ガス
および水蒸気の割合が熱処理温度に応じ著しく変
動する。
このように微量成分である炭酸ガスおよび水蒸
気の割合が変化することは、
2CO＝CO2＋［Ｃ］
CO＋H2＝H2Ｏ＋［Ｃ］
に従い雰囲気ガス中の炭酸ガスおよび水蒸気を計
測して浸炭処理時の活性炭素濃度［Ｃ］を制御す
る方法を採用しようとすると、熱処理温度ごとに
制御条件を変えなければならないことになり、制
御系統が著しく複雑になることを免れない。
また、このように酸化性ガス（炭酸ガス、水蒸
気）の生成量が低温測の熱処理条件下で増大する
ことは、被処理体の粒界酸化層が増加するなど悪
影響を与えることになる。
これに対し本考案の熱処理炉を用いて熱処理を
行つた場合においては、熱処理温度の如何にかか
わらず、雰囲気ガス組成が微量成分である炭酸ガ
スおよび水蒸気を含め一定している上、被処理体
の熱処理に悪影響を与える上記の酸化性ガスの生
成が少ない。
従つて本考案においては、雰囲気ガス中の炭酸
ガスおよび水蒸気を計測して熱処理時の活性炭素
濃度［Ｃ］を制御することが容易であり、また上
記の酸化性ガスの生成量が低温側の熱処理条件下
でも少ないので、熱処理後の品質が安定すること
になる。
第２表と第３表に示した熱処理後の製品の品質
を比較すると、硬度標準偏差値に見られるように
実施例１（および実施例２）の方が良く、本考案
の熱処理炉を用いれば従来のようなバラツキまた
は品質のむらを生じないことがわかる。
実施例 ３
第２図は、本考案の熱処理炉の他の例を示した
断面説明図である。
この実施例における熱分解室５は、第１図に示
した熱分解室５とは、外筒３に設けた第１ガス出
入口Ａを原料ガス供給口９として用いた点、内筒
４に設けた第２ガス出入口Ｂを熱分解ガス導出口
１０として用いた点、内筒内部空間１３に加熱手
段１４の一例として電熱線加熱器を配置した点、
および熱分解室５を横型とした点が異なる。
他の構造については実施例１の場合と同様であ
るので、説明を省略する。
この実施例における熱分解室５内のガスの流れ
は実施例１の場合と逆にした。つまり、原料ガス
供給口９（すなわち第１ガス出入口Ａ）から供給
した原料ガスを内外筒間〓部１２で輻射管型バー
ナ１５の排ガスと熱交換して加熱し、連通口１１
を経て内筒内部空間１３に流入させ、ここで電熱
線加熱器１４により不足する熱を補償して所定の
温度まで加熱して熱分解し、熱分解ガス導出口１
０（すなわち第２ガス出入口Ｂ）から熱処理室１
に送り込み、鉄鋼材（JIS S15CK、SCM21、
SNC21）の浸炭処理を行つた。
熱分解室５に供給する原料ガスの組成は、窒素
55vol％およびメタノール45vol％とした。熱処理
室１における熱処理温度は920℃に設定したが、
被処理体装入時にはそのままでは最大300℃前後
低下する。そこで、排ガス、原料ガスおよび熱分
解ガスの温度を次のように設定した。
排ガス
排ガス入口６温度 1100℃
排ガス出入口７温度 900℃
原料ガス、熱分解ガス
原料ガス供給口９温度 常温
熱分解ガス導出口１０温度 920℃
すなわち、定常状態においては原料ガスは排ガ
スとの熱交換のみによつて920℃にまで高められ
るため電熱線加熱器１４を作動させなかつたが、
被処理体装入時などの熱処理室１内の温度低下に
より排ガス温度も低下するときは、電熱線加熱器
１４を作動させて不足熱量分を補償し、最終的な
熱分解ガス導出口１０温度が常に920℃になるよ
うに制御した。 熱分解ガス導出口１０から熱処
理室１に至る経路から熱分解ガス（つまり雰囲気
ガス）を抽出し、その組成を測定した。結果を第
５表に示す。[Table] The standard deviation of hardness is 0.493 for S15C,
The value is 0.465 for SCM415 and 0.501 for SCr415. For reference, Table 4 shows cases in which carburizing was performed using conventional RX gas. A comparison between Tables 1 and 3 reveals the following. First, comparative example 1 using the usual nitrogen-based heat treatment method.
Since the thermal decomposition behavior of the raw material gas differs depending on the heat treatment temperature, the composition changes considerably when the heat treatment temperature changes, and the proportions of carbon dioxide and water vapor, which are trace components, vary significantly depending on the heat treatment temperature. This change in the ratio of carbon dioxide gas and water vapor, which are trace components, can be explained by measuring carbon dioxide gas and water vapor in the atmospheric gas according to 2CO = CO 2 + [C] CO + H 2 = H 2 O + [C]. If a method of controlling the activated carbon concentration [C] during treatment is adopted, the control conditions must be changed for each heat treatment temperature, and the control system will inevitably become extremely complicated. Further, such an increase in the amount of oxidizing gases (carbon dioxide, water vapor) generated under the heat treatment conditions of low temperature measurements has an adverse effect, such as an increase in the grain boundary oxidation layer of the object to be treated. On the other hand, when heat treatment is performed using the heat treatment furnace of the present invention, regardless of the heat treatment temperature, the atmospheric gas composition remains constant, including trace components of carbon dioxide and water vapor, and the object to be treated is There is little generation of the above-mentioned oxidizing gases that adversely affect heat treatment. Therefore, in the present invention, it is easy to control the active carbon concentration [C] during heat treatment by measuring carbon dioxide gas and water vapor in the atmospheric gas, and the amount of oxidizing gas produced is Since the amount is small even under heat treatment conditions, the quality after heat treatment is stable. Comparing the quality of the products after heat treatment shown in Tables 2 and 3, as seen in the hardness standard deviation values, Example 1 (and Example 2) is better, and the heat treatment furnace of the present invention is better. It can be seen that there is no variation or unevenness in quality as in the conventional method. Example 3 FIG. 2 is a cross-sectional explanatory diagram showing another example of the heat treatment furnace of the present invention. The pyrolysis chamber 5 in this embodiment is different from the pyrolysis chamber 5 shown in FIG. The second gas inlet/outlet B is used as the pyrolysis gas outlet 10, the heating wire heater is arranged in the inner cylinder space 13 as an example of the heating means 14,
The difference is that the thermal decomposition chamber 5 is of a horizontal type. The other structures are the same as those in the first embodiment, so their explanation will be omitted. The flow of gas in the pyrolysis chamber 5 in this example was reversed to that in Example 1. That is, the raw material gas supplied from the raw material gas supply port 9 (i.e., the first gas inlet/outlet A) is heated by exchanging heat with the exhaust gas of the radiant tube burner 15 in the inner and outer cylinder interface part 12, and is heated through the communication port 11.
The gas flows into the inner cylinder space 13 through the heating wire heater 14, where it is heated to a predetermined temperature and thermally decomposed by compensating for the insufficient heat.
0 (that is, the second gas inlet/outlet B) to the heat treatment chamber 1
The steel materials (JIS S15CK, SCM21,
SNC21) was carburized. The composition of the raw material gas supplied to the pyrolysis chamber 5 is nitrogen.
55 vol% and methanol 45 vol%. The heat treatment temperature in heat treatment chamber 1 was set at 920°C.
When the object to be processed is loaded, the temperature will drop by around 300°C at most. Therefore, the temperatures of the exhaust gas, raw material gas, and pyrolysis gas were set as follows. Exhaust gas Exhaust gas inlet 6 temperature 1100°C Exhaust gas inlet 7 temperature 900°C Raw material gas, pyrolysis gas Raw gas supply port 9 temperature Room temperature Pyrolysis gas outlet 10 temperature 920°C In other words, in steady state, the raw material gas only exchanges heat with the exhaust gas The heating wire heater 14 was not activated because the temperature was raised to 920℃ by
When the temperature of the exhaust gas decreases due to a decrease in the temperature inside the heat treatment chamber 1, such as when loading an object to be treated, the heating wire heater 14 is operated to compensate for the insufficient amount of heat, and the final temperature at the pyrolysis gas outlet 10 is lowered. was controlled so that the temperature was always 920℃. Pyrolysis gas (that is, atmospheric gas) was extracted from the path leading from the pyrolysis gas outlet 10 to the heat treatment chamber 1, and its composition was measured. The results are shown in Table 5.
【表】
また、この熱分解ガスを用いて浸炭を行つた後
の鉄鋼材の硬度等の品質も良好であつた。
実施例 ４
実施例３で用いた熱処理炉において、熱分解室
５内のガスの流れを逆にする。
すなわち、内筒４に設けた第２ガス出入口Ｂを
原料ガス供給口９として用い、外筒３に設けた第
１ガス出入口Ａを熱分解ガス導出口１０として用
いる如く改装した熱処理炉を用いて、実施例３と
同一組成の原料ガスを第２ガス出入口Ｂから供給
し、内筒内部空間１３、連通口１１、内外筒間〓
部１２を経て第１ガス出入口Ａから熱処理室１へ
送り込んで、実施例３と同じ熱処理温度で同じ鉄
鋼材の浸炭を行つた。その結果、熱分解ガスの組
成、浸炭後の品質ともに実施例３の場合とほぼ同
一の成績を得た。
考案の効果
本考案の熱処理炉を用いれば、熱処理温度の如
何にかかわらず雰囲気ガス組成が一定しているの
で、被処理体の熱処理を安定して行うことができ
る。しかも、たとえばRXガスに相当する雰囲気
ガスを得る場合、酸化性ガス（炭酸ガス、水蒸
気）の生成量が低温側の熱処理条件下でも少ない
ので、熱処理後の品質がすぐれている。
また、このように熱処理温度が変化しても原料
ガスの分解挙動が一定し、しかも微量成分である
炭酸ガスおよび水蒸気の割合も一定しているた
め、雰囲気ガス中の炭酸ガスおよび水蒸気を計測
して浸炭処理時の活性炭素濃度［Ｃ］を制御する
制御系統が簡単となり、制御の精度も高くなる。
加えて原料ガスの熱分解が熱分解室５内で完全
に行われるため、生成する雰囲気ガス量が多くな
り、従つて同一容量の雰囲気ガスを得るのに要す
る原料ガスの量がそれだけ低減し、資源の有効利
用に役立ち、運転経費上も有利となる。
そして本考案においては、原料ガス供給口９か
ら熱分解室５内に供給された原料ガスを、熱分解
ガス導出口１０から導出するまでの間に、最外筒
２と外筒３との間〓部８を流れる熱処理排ガスと
の間で熱交換して熱分解するので、排ガスの保持
する熱量を原料ガスの分解に有効利用できる。
熱分解に不足する熱量は、内筒内部空間１３を
通過する間に加熱手段１４により補償するので、
完全な熱分解が可能である。また、排ガスの保有
する熱量を利用しているので、加熱手段１４が熱
エネルギー発生能力の比較的小さいものを用いる
ことができ、この加熱手段１４を作動させるエネ
ルギーも節約できるので有利である。
このように本考案の熱処理炉においては、原料
ガスは、内外筒間〓部１２から内筒内部空間１３
を経て（あるいはその逆のルートで）熱処理室１
に送り込まれるので、熱分解室５内での滞留時間
が長く、従つて原料ガスの熱分解不足を生ずるお
それがなく、分解操作を安定して行うことができ
る。
また、従来においては熱処理温度が低いため窒
素ベース熱処理法を適用できなかつた軟窒化処理
にも、本考案の熱処理炉を用いれば適用が可能と
なる。
加えて、熱分解室５の設置は装置費上それほど
負担が大きいものではなく（触媒を用いる装置に
比べて装置が簡単かつ小型になり、設備の保全も
容易となる）、また先にも述べたように排ガスの
保有する熱量が原料ガスの熱分解に有効利用され
るので、併用した加熱手段１４の作動は被処理体
装入時に熱処理炉が温度低下するときや熱処理温
度が低いときにその温度不足分を補償するだけで
足り、従つて加熱手段１４の熱エネルギー発生能
力の点でもそれほどの負担にはならない。
なお本考案は原料ガスの熱分解を伴うものであ
るため、窒素−メタノール、窒素−液化石油ガス
のどの組合せなどの場合には煤発生を完全には防
止できないこともあるが、煤が発生しても煤の付
着は熱処理室１に付設した熱分解室５内にとどめ
ることができるため、熱処理室１自体はほとんど
汚染されず、従つて熱処理室１内の洗浄を保つこ
とができる。また、熱分解室５内に空気を導入で
きる構造とすれば、たとえ熱分解室５内に煤が付
着しても、その煤を簡単に燃焼除去することがで
きる。
よつて上述の種々の長所を考慮すると、熱分解
室５設置のための装置費や加熱手段１４作動のた
めに要するエネルギーなどの不利をはるかに上回
る利点がある。[Table] In addition, the quality of the steel material, such as hardness, was also good after carburizing using this pyrolysis gas. Example 4 In the heat treatment furnace used in Example 3, the flow of gas in the pyrolysis chamber 5 is reversed. That is, using a heat treatment furnace that has been renovated so that the second gas inlet/outlet B provided in the inner cylinder 4 is used as the raw material gas supply port 9, and the first gas inlet/outlet A provided in the outer cylinder 3 is used as the pyrolysis gas outlet 10. , a source gas having the same composition as in Example 3 is supplied from the second gas inlet/outlet B, and the space between the inner cylinder internal space 13, the communication port 11, and the inner and outer cylinders is
The gas was fed into the heat treatment chamber 1 through the first gas inlet/outlet A through the gas section 12, and the same steel material was carburized at the same heat treatment temperature as in Example 3. As a result, almost the same results as in Example 3 were obtained in both the composition of the pyrolysis gas and the quality after carburization. Effects of the Invention If the heat treatment furnace of the present invention is used, the atmospheric gas composition is constant regardless of the heat treatment temperature, so that the object to be treated can be stably heat treated. Moreover, when obtaining an atmospheric gas corresponding to, for example, RX gas, the amount of oxidizing gas (carbon dioxide gas, water vapor) produced is small even under low-temperature heat treatment conditions, so the quality after heat treatment is excellent. In addition, even if the heat treatment temperature changes, the decomposition behavior of the raw material gas remains constant, and the proportions of carbon dioxide and water vapor, which are trace components, are also constant, so it is possible to measure carbon dioxide and water vapor in the atmospheric gas. This simplifies the control system for controlling the activated carbon concentration [C] during carburization, and improves control accuracy. In addition, since the thermal decomposition of the raw material gas is completely carried out within the pyrolysis chamber 5, the amount of atmospheric gas generated increases, and therefore the amount of raw material gas required to obtain the same volume of atmospheric gas is reduced accordingly. This helps in the effective use of resources and is advantageous in terms of operating costs. In the present invention, there is a gap between the outermost cylinder 2 and the outer cylinder 3 before the raw material gas supplied into the pyrolysis chamber 5 from the raw material gas supply port 9 is led out from the pyrolysis gas outlet 10. Since thermal decomposition is performed by exchanging heat with the heat-treated exhaust gas flowing through the bottom section 8, the amount of heat held by the exhaust gas can be effectively used for decomposing the raw material gas. The amount of heat insufficient for thermal decomposition is compensated for by the heating means 14 while passing through the inner cylinder internal space 13.
Complete thermal decomposition is possible. Furthermore, since the amount of heat possessed by the exhaust gas is utilized, it is possible to use a heating means 14 having a relatively small thermal energy generation capacity, which is advantageous because the energy for operating the heating means 14 can also be saved. In this way, in the heat treatment furnace of the present invention, the raw material gas flows from the inner and outer cylinder space 12 to the inner cylinder inner space 13.
(or the reverse route) to heat treatment chamber 1
Since the raw material gas is sent into the thermal decomposition chamber 5 for a long time, there is no fear that the raw material gas will be insufficiently decomposed, and the decomposition operation can be performed stably. Furthermore, the heat treatment furnace of the present invention can be applied to nitrocarburizing, to which nitrogen-based heat treatment could not be applied conventionally due to the low heat treatment temperature. In addition, installing the pyrolysis chamber 5 is not a big burden in terms of equipment costs (compared to equipment that uses a catalyst, the equipment is simpler and smaller, and the equipment is easier to maintain), and as mentioned earlier. As described above, since the amount of heat held by the exhaust gas is effectively used for thermal decomposition of the raw material gas, the operation of the heating means 14 used in conjunction with the heating means 14 is limited when the temperature of the heat treatment furnace decreases when the object to be treated is charged or when the heat treatment temperature is low. It is sufficient to compensate for the temperature deficiency, and therefore there is no significant burden on the thermal energy generation capacity of the heating means 14. Since the present invention involves thermal decomposition of the raw material gas, it may not be possible to completely prevent soot generation in the case of combinations such as nitrogen-methanol or nitrogen-liquefied petroleum gas. However, the adhesion of soot can be kept within the pyrolysis chamber 5 attached to the heat treatment chamber 1, so that the heat treatment chamber 1 itself is hardly contaminated, and therefore the inside of the heat treatment chamber 1 can be kept clean. Moreover, if the structure is such that air can be introduced into the pyrolysis chamber 5, even if soot adheres to the inside of the pyrolysis chamber 5, the soot can be easily burned and removed. Therefore, considering the various advantages mentioned above, the advantages far outweigh the disadvantages such as the cost of equipment for installing the pyrolysis chamber 5 and the energy required for operating the heating means 14.
第１図は、本考案の熱処理炉の一例を示した断
面説明図である。第２図は、本考案の熱処理炉の
他の例を示した断面説明図である。
１……熱処理室、２……最外筒、３……外筒、
４……内筒、５……熱分解室、６……排ガス入
口、７……排ガス出入口、８……最外筒２と外筒
３との間〓部、９……原料ガス供給口、１０……
熱分解ガス導出口、１１……連通口、１２……内
外筒間〓部、１３……内筒内部空間、１４……加
熱手段、１５……輻射管型バーナ、１６……外
壁、１７……フアン、１８……エジエクター、１
９……熱処理雰囲気原料ガス供給系、２０……空
気供給系、２１……被処理体、Ａ……第１ガス出
入口、Ｂ……第２ガス出入口。
FIG. 1 is an explanatory cross-sectional view showing an example of the heat treatment furnace of the present invention. FIG. 2 is an explanatory cross-sectional view showing another example of the heat treatment furnace of the present invention. 1...Heat treatment chamber, 2...Outermost cylinder, 3...Outer cylinder,
4... Inner cylinder, 5... Pyrolysis chamber, 6... Exhaust gas inlet, 7... Exhaust gas inlet/outlet, 8... Part between outermost cylinder 2 and outer cylinder 3, 9... Raw material gas supply port, 10...
Pyrolysis gas outlet, 11...Communication port, 12...Between the inner and outer cylinders, 13...Inner cylinder interior space, 14...Heating means, 15...Radiation tube type burner, 16...Outer wall, 17... ...Juan, 18...Egiector, 1
9... Heat treatment atmosphere raw material gas supply system, 20... Air supply system, 21... Processed object, A... First gas inlet/outlet, B... Second gas inlet/outlet.
Claims (1)
処理体の熱処理を行うための熱処理炉におい
て、 熱処理室１の外部に熱分解室５を設けるこ
と、 該熱分解室５は、最外筒２、外筒３および内
筒４からなる三重筒の形状を有し、かつ熱処理
雰囲気原料ガスと排ガスとの間で熱交換する熱
交換器の構造を有し、さらに加熱手段１４を備
えていること、 上記熱分解室５の最外筒２には排ガス入口６
と排ガス出口７とを設けて最外筒２と外筒３と
の間〓部８を排ガス流路となすこと、 上記熱分解室５の外筒３には第１ガス出入口
Ａを、内筒４には第２ガス出入口Ｂを、さら
に、内筒４には内外筒間〓部１２との連通口１
１を設け、 ［イ］ 第１ガス出入口Ａを熱処理雰囲気原料
ガス供給系１９と接続して原料ガス供給口９
として用い、一方第２ガス出入口Ｂを熱処理
室ガス供給口と接続して熱分解ガス導出口１
０として用いるか、あるいは、 ［ロ］ 第２ガス出入口Ｂを熱処理雰囲気原料
ガス供給系１９と接続して原料ガス供給口９
として用い、一方第１ガス出入口Ａを熱処理
室ガス供給口と接続して熱分解ガス導出口１
０として用いること、 上記加熱手段１４は、熱分解室５内部の内外筒
間〓部１２、連通口１１、内筒内部空間１３を繋
ぐガス流路を熱処理雰囲気原料ガスが流通する間
に該ガスを熱分解するために、内筒内部空間１３
内に設置すること、 を特徴とする熱処理炉。 ２ 加熱手段１４として、熱処理室１内の高温の
雰囲気ガスを排出したときの排ガスの保有する
熱量を利用する熱交換器を用いることを特徴と
する実用新案登録請求の範囲第１項記載の熱処
理炉。 ３ 加熱手段１４として、電熱線加熱器を用いる
ことを特徴とする実用新案登録請求の範囲第１
項記載の熱処理炉。[Claims for Utility Model Registration] 1. In a heat treatment furnace for heat-treating objects to be treated in an inert gas-based gas atmosphere, a pyrolysis chamber 5 is provided outside the heat treatment chamber 1; The chamber 5 has the shape of a triple cylinder consisting of the outermost cylinder 2, the outer cylinder 3, and the inner cylinder 4, and has a structure of a heat exchanger for exchanging heat between the heat treatment atmosphere raw material gas and the exhaust gas. The outermost cylinder 2 of the pyrolysis chamber 5 has an exhaust gas inlet 6.
and an exhaust gas outlet 7 to form a part 8 between the outermost cylinder 2 and the outer cylinder 3 as an exhaust gas flow path; 4 has a second gas inlet/outlet B, and furthermore, the inner cylinder 4 has a communication port 1 with the inner and outer cylinder part 12.
[A] Connect the first gas inlet/outlet A to the heat treatment atmosphere raw material gas supply system 19 to open the raw material gas supply port 9.
On the other hand, the second gas inlet/outlet B is connected to the heat treatment chamber gas supply port to connect the pyrolysis gas outlet 1.
0, or [B] The second gas inlet/outlet B is connected to the heat treatment atmosphere raw material gas supply system 19 and the raw material gas supply port 9 is used.
On the other hand, the first gas inlet/outlet A is connected to the heat treatment chamber gas supply port to connect the pyrolysis gas outlet 1.
0, the heating means 14 is configured to heat the raw material gas in the heat treatment atmosphere while it flows through the gas flow path connecting the inner and outer cylinder parts 12, the communication port 11, and the inner cylinder internal space 13 inside the pyrolysis chamber 5. In order to thermally decompose the inner cylinder internal space 13
A heat treatment furnace characterized by: being installed in a furnace. 2. The heat treatment according to claim 1 of the utility model registration, characterized in that the heating means 14 is a heat exchanger that utilizes the amount of heat held in the exhaust gas when the high-temperature atmospheric gas in the heat treatment chamber 1 is discharged. Furnace. 3 Utility model registration claim 1 characterized in that a heating wire heater is used as the heating means 14
The heat treatment furnace described in section.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1986061493U JPH0512277Y2 (en) | 1986-04-22 | 1986-04-22 |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1986061493U JPH0512277Y2 (en) | 1986-04-22 | 1986-04-22 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS62175069U JPS62175069U (en) | 1987-11-06 |
| JPH0512277Y2 true JPH0512277Y2 (en) | 1993-03-29 |
Family
ID=30894883
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1986061493U Expired - Lifetime JPH0512277Y2 (en) | 1986-04-22 | 1986-04-22 |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0512277Y2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2012506025A (en) * | 2008-10-20 | 2012-03-08 | エープナー インドゥストリーオーフェンバウ ゲゼルシャフト ミット ベシュレンクテル ハフツング | Heat exchanger for an annealing furnace to exchange heat between two fluids |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5634797B2 (en) * | 2010-08-24 | 2014-12-03 | 大陽日酸株式会社 | Heat treatment atmosphere gas generation method and apparatus, and metal oxide heat treatment method |
| CN107532853B (en) | 2015-05-01 | 2020-06-30 | 株式会社Ihi | Heat treatment apparatus |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5722973A (en) * | 1980-07-14 | 1982-02-06 | Mitsubishi Agricult Mach Co Ltd | Falldown preventive device of tractor |
| JPS5722972A (en) * | 1980-07-16 | 1982-02-06 | Kubota Ltd | Steering device of working vehicle |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58163551U (en) * | 1982-04-22 | 1983-10-31 | 関東冶金工業株式会社 | Atmosphere heating furnace |
-
1986
- 1986-04-22 JP JP1986061493U patent/JPH0512277Y2/ja not_active Expired - Lifetime
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5722973A (en) * | 1980-07-14 | 1982-02-06 | Mitsubishi Agricult Mach Co Ltd | Falldown preventive device of tractor |
| JPS5722972A (en) * | 1980-07-16 | 1982-02-06 | Kubota Ltd | Steering device of working vehicle |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2012506025A (en) * | 2008-10-20 | 2012-03-08 | エープナー インドゥストリーオーフェンバウ ゲゼルシャフト ミット ベシュレンクテル ハフツング | Heat exchanger for an annealing furnace to exchange heat between two fluids |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS62175069U (en) | 1987-11-06 |
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