JP2004308941A

JP2004308941A - Supporting structure of thermal insulation member in high temperature microwave heating furnace

Info

Publication number: JP2004308941A
Application number: JP2003099424A
Authority: JP
Inventors: Tsuneo Kiriyama; 恒夫桐山; Akihiko Negishi; 晃彦根岸
Original assignee: Saint Gobain TM KK
Current assignee: Saint Gobain TM KK
Priority date: 2003-04-02
Filing date: 2003-04-02
Publication date: 2004-11-04
Anticipated expiration: 2023-04-02
Also published as: JP4129865B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal insulation structure of a high temperature microwave heating furnace enabling the stable operation of the furnace by preventing an adjacent thermal insulation member from being deformed or a closed space surrounded by the thermal insulation members from being deformed by the expanding or contracting movement of a thermal insulation member in the operation of the furnace. <P>SOLUTION: In this supporting structure of the thermal insulation member in the high temperature microwave heating furnace in which microwave is used as a heating source, the thermal insulation members are formed so as to surround heated materials 7 disposed in the furnace by the thermal insulation members 6. The thermal insulation members comprise side wall portions and a ceiling portion, generally the total weight of the thermal insulation members at the ceiling portion is supported by a support body. The weight of the thermal insulation members at the ceiling portion is substantially not applied to the thermal insulation members at the side wall portions. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、高温用マイクロ波加熱炉における断熱部材の支持構造に関し、さらにいえば、たとえば高温用マイクロ波加熱炉において、被加熱物を囲むように閉空間を構成する断熱部材の、天井部分の支持構造に関する。
【０００２】
【関連の技術】
マイクロ波加熱は、マイクロ波電力を誘電体に吸収させて誘電体（被加熱物）の内部より自己発熱させるものである。
【０００３】
このため、ガス、電気抵抗等を熱源とした、熱伝導や輻射による従来の加熱方式に比べて、マイクロ波加熱は、急速加熱が可能となり、しかも熱効率が高いため、短時間で加熱処理を行うことができる。
【０００４】
この原理を応用して、マイクロ波加熱は、ゴムの加熱加硫や木材の接着乾燥装置として広く利用されている。
【０００５】
また、これら低温用途の他に、高温用途としてセラミックや陶器等の焼成用のマイクロ波加熱炉が特許文献１に、電子レンジを利用して焼成を行う焼成炉が特許文献２にそれぞれ記載されている。このような高温用途においては、被加熱物の自己発熱によって発生した熱を放散させないように、被加熱物を断熱材で囲む必要があった。
【０００６】
【特許文献１】特公昭５９−２５９３７号公報
【０００７】
【特許文献２】特開平７−３１８２６２号公報
高温用途のマイクロ波加熱炉は、主に、マイクロ波発振装置、マイクロ波の発振口である導波管、マイクロ波を散らすためのファン、マイクロ波の漏洩を防止するケーシング、及び断熱材からなる。
【０００８】
上記公報に示されている、これまでの高温用途のマイクロ波加熱炉は、小型であった。そのため、被加熱物を囲む閉空間（炉内の空間）を断熱材で構築する際に、側壁部分と天井部分をほぼー体に成形した単体の断熱材を用いることができた。その結果、断熱材を支持するための支持体は特に必要がなかった。即ち、一体に成形した断熱材は、そのままで力学的に安定に自立することができた。
【０００９】
しかし、炉を大型化する場合、断熱材で構築された広い閉空間が必要になる。この広い空間を構築するためには、複数の断熱材を組み合わせて側壁部分や天井部分を構成する必要が生じた。その結果、複数の断熱材を支持し、固定する必要が生じた。
【００１０】
他方、一般に、ガス、電気抵抗等を熱源とした従来の加熱方式の大型炉においては、断熱部材の固定方法としては、棒状あるいは爪状の金属製支持体を使用して、外枠を兼ねた強度のある金属製ケーシングに断熱材を固定する方法が一般的である。
【００１１】
一方、マイクロ波は、金属の一部に吸収されて熱を発生させるが、金属の大部分により反射する性質を持つ。この性質は、必要に応じて使い分けられている。例えば、一般の電子調理器、またマイクロ波を熱源とした加熱炉ではマイクロ波が金属によって反射する性質を利用して、金属で調理器や炉全体を囲い、炉外ヘマイクロ波が漏れないようにして危険防止を図っている。
【００１２】
さらに、高温でマイクロ波加熱を行うためには、考慮すべき点がある。即ち、ａ）被加熱物を断熱部材で覆い、断熱部材の外側にマイクロ波発振器及び導波管を配置しなければならない。これは、断熱部材の使用により、被加熱物自身から発生する高熱を、断熱部材で覆った閉空間に閉じこめて、被加熱物を高温に保つと共に、断熱部材の外側を低温に保ち、マイクロ波発振器及び導波管が損傷しないようにするためである、従って、内側より、被加熱物、断熱材、発振器及び導波管を順に設ける。
【００１３】
ｂ）炉の運転中、断熱部材で構成した閉空間が、大きく変形することなく安定である必要がある。断熱部材で構成した閉空間が大きく変形すると、炉内（閉空間内）からの熱が、断熱部材の隙間から漏れたり、閉空間自身が崩れたりして危険である。
【００１４】
ｃ）一方、マイクロ波は発振器から導波管を通して発振され、閉空間を構成する外側の断熱部材を透過して、効率よく最も内側にある被加熱物に達する必要がある。従って、少なくとも導波管と被加熱物の間には、それを妨げるような部材、または自身が溶損して本来の機能を失うような部材を配置することはできるだけ避ける必要がある。例えば、金属製の板、支持体等は、そのままでは配置して使用できない。
【００１５】
ｄ）断熱部材は、マイクロ波による被加熱物の発熱を妨げないような材質、つまり、マイクロ波に対して透過性の優れた材質であることが必要である。これは、断熱部材がマイクロ波を多く吸収してしまうと、被加熱物にマイクロ波が到達しなくなり、被加熱物自身の発熱が起こりにくくなるからである。言い換えると、断熱部材、支持体、接着材は、誘電損失が被加熱物と同じか、又は被加熱物よりも小さいことが必要である。
【００１６】
ｅ）人体に対して安全性を確保するため、マイクロ波が炉の外側に漏れ出ることは防止しなければならない。即ち、少なくとも断熱部材の外側を覆い、閉空間を作る金属製ケーシングが必要である。
【００１７】
ここで、ａ）、ｄ）に関する手段は、既に特願２００１−３３９１６２号で提案されている。
【００１８】
又、本発明者は、炉の大型化について、既に、特願２００２−０３３９９２号、特願２００２−０３４０４５号、特願２００２−０３４８０１号で、被加熱物を囲んで構成する閉空間（炉内）を、複数の断熱部材、及び、誘電損失が被加熱物と同じか、被加熱物よりも小さい材料の支持体で構築する、高温用マイクロ波加熱炉の断熱構造を提案している。
【００１９】
【発明が解決しようとする課題】
しかし、炉を大型化する際、天井や、天井と側壁が接する部分に断熱部材として焼成耐火物や、セラミックファイバーボード等を、例えば天井をアーチ構造にして使用すると、炉の運転中に断熱部材の加熱時の膨張、降温時の収縮、特に天井部分の断熱部材の動きによって、側壁都分の断熱部材が外側（炉外側）に押され、押された状態で、天井部分の断熱部材の重量がかかるため断熱部材で構成する閉空間が変形し、炉の運転が安定に行えなくなる。特に炉が大型化すると、天井部分の断熱部材も重量が増加し、一層閉空間を構成する断熱部材の変形が起こりやすい、という問題が生じる。
【００２０】
本発明の目的は、炉の運転時に天井部分の断熱部材の膨張・収縮の動きによって、側壁部分の断熱部材が変形したり、それにより、断熱部材で囲まれた閉空間が変形することなく、安定して炉の運転が行える高温用マイクロ波加熱炉の断熱構造を提供することである。
【００２１】
【課題を解決するための手段】
本発明者は、高温用マイクロ波加熱炉における前述の課題を解決するために鋭意検討の結果、高温用マイクロ波加熱炉の天井部分の支持方法を改良して、特に、天井部分の断熱部材を、誘電損失が被加熱物と同じか、または被加熱物よりも小さい材料の支持体によって、側壁の断熱部材とは独立して、天井部分の大半の重量を支持し、好ましくは側壁部分の断熱部材に天井部分の断熱部材の荷重が実質的にかからないようにすることによって、課題を解決できることを見出し、本発明を完成させた。
【００２２】
本発明の解決手段を例示すると、各請求項に記載の高温用マイクロ波加熱炉断熱部材の支持構造である。
【００２３】
ここで、好ましくは、ケーシングは金属製であって、導波管よりも外側に位置し、マイクロ波が炉外に漏れることを防止するため、及び、支持体を支持、固定するためのものである。
【００２４】
【発明の実施の形態】
本発明は、マイクロ波を加熱源として用いる高温用マイクロ波加熱炉の、天井部分の断熱部材の支持構造を改良したものである。
【００２５】
通例、炉の内側より順に、被加熱物、断熱部材及び支持体、金属製ケーシングを配置する。金属製ケーシングにマイクロ波の発振口である導波管を設け、導波管から被加熱物に向けてマイクロ波を照射する。金属製ケーシングの内側に、被加熱物を囲うように、断熱部材を壁の形で用いて閉空間を構成し、その断熱部材を支持体で支持する。
【００２６】
本発明による高温用マイクロ波加熱炉の支持構造では、特に、天井部分の断熱部材を、誘電損失が被加熱物と同じか、または被加熱物よりも小さい材料の支持体によって、側壁部分の断熱部材とは独立して、天井部分の大半の重量を支持して、好ましくは側壁部分の断熱部材に天井部分の断熱部材の荷重が実質的にかからないようにする。このようにして炉の運転時において、断熱部材が構成する閉空間（炉内）が、断熱部材、特に、天井部分の断熱部材の熱変動たとえば膨張、収縮の動きによって、変形するのを防止し、安定して炉の運転が行えるようにするものである。
【００２７】
本発明の好ましい支持構造を図に基づいて説明する。
【００２８】
まず、天井部分の断熱部材の支持構造について説明する。
【００２９】
図１は、第１の支持構造の概念図である。天井部分の断熱部材の第１の支持構造は、閉空間（炉内）の天井部分を構成する断熱部材を、吊り具支持体１と、ワッシャ状支持具２、チューブ状若しくは棒状支持体３を用いて支持する構造である。これらの支持部材の材料はいずれも誘電損失の小さい材料、例えばアルミナの焼結体が好適である。吊り具支持体１は、例えば上端部がフック状、下端部がワッシャ状支持具を固定するためにネジ加工が施されているものが好適であるが、吊り具支持体１の下端部は、吊り具支持体１とワッシャ状支持具２が嵌合するようにして固定するなど、吊り具支持体１を固定できれば特に制限されない。吊り具支持体１は、フック状とした上端部を、チューブ状若しくは棒状支持体３に引っ掛け、下端部は断熱部材を垂直方向に貫通して、断熱部材の炉内面においてワッシャ状支持具２で固定して断熱部材を支持する。
【００３０】
又、吊り具支持体１は、上端部をフック状とせず、吊り具支持体１に設けた水平方向の貫通孔にチューブ状若しくは棒状支持体３を通して支持しても良い。
【００３１】
チューブ状若しくは棒状支持体３は、金属製ケーシング１１の一方の側面から、他方の側面へ水平方向に渡して、金属製ケーシング１１と接した部分で支持され、固定される。この場合チューブ状若しくは棒状支持体３は、少なくとも、上述の金属製ケーシング１１の両側面間の距離を渡すことのできる長尺のものが適している。
【００３２】
図２は、上端部をフック状とした吊り具支持体１の概念図である。
【００３３】
次に天井部分の断熱部材の第２の支持構造について説明する。
【００３４】
図３は、第２の支持方法の概念図である。
【００３５】
第２の支持構造は、チューブ状若しくは棒状支持体を使用せず、吊り具支持体１の上端部を金属製ケーシング１１の上面外側において、筒状ホルダー４とピン５を用いて、又はワッシャ状支持具２を用いて支持し、下端部を断熱部材６の炉内面でワッシャ状支持具２により支持する構造である。
【００３６】
この場合、例えば、図５に示すように、断熱部材６を貫通した吊り具支持体１の上端部を、金属製ケーシング１１に設けた孔から突出させ、突出させた吊り具支持体１に筒状ホルダー４を被せ、吊り具支持体１の上端部近くの側面に設けた貫通孔と筒状ホルダー４の側面に設けた貫通孔に棒状のピン５をそれぞれに差し込み渡すことによって支持する構造が好適である。
【００３７】
また、図６のように、筒状ホルダー４を用いず、上端部をネジ加工した吊り具支持体１と、貫通孔をネジ加工したワッシャ状支持具２を用いて螺合させたり、あるいは吊り具支持体１と、ワッシャ状支持具２が嵌合するように加工して、支持しても艮い。
【００３８】
一方、吊り具支持体１は、断熱部材６を垂直方向に貫通して断熱部材６の炉内面で、吊り具支持体１の下端部にワッシャ状支持具２を固定することによって、断熱部材６を支持する。ここで、ワッシャ状支持具２の固定は、図７のように、端部をネジ加工した吊り具支持体１と、貫通孔をネジ加工したワッシャ状支持具２を用いて螺合させる構造や、吊り具支持体１と、ワッシャ状支持具２が嵌合するように加工して、支持する構造などが好適である。
【００３９】
次に天井部分の断熱部材の第３の支持構造について説明する。
【００４０】
図４は、第３の支持構造の概念図である。天井部分の断熱部材の第３の支持構造は、チューブ状若しくは棒状支持体３を、天井部分の断熱部材６に水平方向に貫通させ、チューブ状若しくは棒状支持体３は、吊り具支持体１が支持し、吊り具支持体１は、その上端部が金属製ケーシング１１から突出して金属製ケーシング１１の外側で、ホルダー４及びピン５によって、またはワッシャ状支持具２によって支持されることで、天井部分の断熱部材６を支持する。また、天井部分の断熱部材６を水平方向に貫通したチューブ状若しくは棒状支持体３は、必要に応じて、その両端を金属製ケーシングの側面で支持しても良い。また、吊り具支持体１の下端部はフック状として、チューブ状若しくは棒状支持体３を支持しても良い。または、吊り具支持体１の下端部に水平方向に設けた貫通孔に、チューブ状若しくは棒状支持体３を通して、チューブ状若しくは棒状支持体３を支持しても良い。
【００４１】
この場合、チューブ状若しくは棒状支持体３は、天井の断熱部材６を水平方向に支持できる長さがあればよい。
【００４２】
吊り具支持体１、チューブ状若しくは棒状支持体３の使用数は、炉の大きさに応じて任意に増減させてよいが、吊り具支持体１は、およそ２００〜４００ｍｍ間隔で、チューブ状若しくは棒状支持体３１は、およそ３００〜５００ｍｍ程度の間隔で配する事が好適である。
【００４３】
次に側壁部分の断熱部材の支持構造について説明する。
【００４４】
本発明においては、好ましくは、天井部分の断熱部材が側壁部分とは独立に支持されているので、側壁部分の断熱部材は、自身の膨張収縮の動きや、地震など外力による動きに対して安全であるような（大きな変形を起こさない）支持を行えばよい。側壁部分を構成する断熱部材は、対向面に位置する金属製ケーシングの一方の側面から、対向する他方の側面に支持体を渡して、断熱部材を支持体により支持することが好適である。
【００４５】
さらに、好ましくは、支持体は、金属製ケーシングと接した部分で支持されて固定される。この場合、支持体は、上述のように、長尺の支持体が適している。側壁部分を構成する断熱部材を支持する長尺の支持体は、少なくともその一部で断熱部材の外側または表面を支持すればよい。また支持体で断熱部材を貫通して支持しても良く、短尺の支持体で、隣接する断熱部材同士を互いに貫通して支持しても良い。
【００４６】
図８は、高温用マイクロ波加熱炉全体の概念図である。
【００４７】
以上のように、天井部分の断熱部材を側壁部分の断熱部材とは独立に支持して、天井部分の断熱部材の荷重が、側壁部分の断熱部材に実質的にかからないようにするのが好ましい。
【００４８】
このようにすることによって、高温用マイクロ波加熱炉の運転時に、断熱部材が構成する閉空間（炉内）が、断熱部材の膨張、収縮の動きによって、変形することを防止でき、安定して炉の運転をが行うことができる。
【００４９】
金属製ケーシングよりも内側に配置する吊り具支持体、チューブ状若しくは棒状支持体、ワッシャ状支持具は、前述のように、安全に配置される。従って、マイクロ波透過性及び耐熱性に優れ、高温での強度があり、成形や加工が容易な材料が好ましく、非金属かつ無機質材料が好適であり、例えばアルミナ質、ムライト質、ステアタイト質、ジルコン質、コーディエライト質、シリカ質、石英、炭化ケイ素、窒化ケイ素等からなる耐火物が好ましい。
【００５０】
高温用マイクロ波加熱炉において、使用する材料と被加熱物のマイクロ波に対する性質は重要である。材料に対する、マイクロ波の透過、反射、吸収を考えた場合、マイクロ波の透過性に優れた材料は、言い換えればマイクロ波を反射、吸収しにくい性質を持っているものである。その性質を表すひとつの要素として誘電損失がある。
【００５１】
誘電損失が大きい材料は、マイクロ波を吸収しやすい。その結果、材料の発熱量が多くなる。従って、高温用マイクロ波加熱炉においては、被加熱物よりも高温になってしまい、高温で必要な強度を維持できなくなり、また、このような材料が被加熱物の近くにあれば、これら材料からの熱の影響を受け、被加熱物の正確な温度制御が困難となる。さらに、マイクロ波が被加熱物に届く前にこれらの材料に吸収されてしまい、被加熱物の発熱効率が悪くなるため好ましくない。
【００５２】
つまり、高温用マイクロ波加熱炉においては、断熱部材を支持する支持体等は、その誘電損失が被加熱物と同じか、または被加熱物よりも小さいことが好ましい。例えば、被加熱物がムライトである場合は、支持体等はムライトまたはアルミナが好ましい材料であり、被加熱物がアルミナである場合は、支持体等はアルミナであることが好ましい。
【００５３】
本発明で用いる吊り具支持体は、棒状、または、チューブ状が好適であり、端部は必要に応じてフック状、ネジ加工など、支持に適した形状とすることが好ましい。吊り具支持体の棒状、またはチューブ状である部分の断面が、例えば円形の場合では、その直径は、棒状で５〜２０ｍｍ程度、チューブ状で外径２０〜４０ｍｍ程度が好ましい。
【００５４】
本発明で主に水平方向に用いるチューブ状若しくは棒状支持体は、断面の形状、断面の幅、径等は任意のものでよい。ただし、幅、径が小さすぎると支持体としての強度が不足し、大きすぎると、支持体にマイクロ波が吸収される量が多くなり、被加熱物を効率よく加熱できなくなる。これは、吊り具支持体についても同様である。
【００５５】
支持体は、材料の入手のしやすさ、価格、加工性、施工性を考慮するとチューブ状にするのが最も好ましい。主に水平方向に用いるチューブ状若しくは棒状支持体では、その断面が、例えば円形の場合では、その直径は、１０〜４０ｍｍ程度が好ましい。
【００５６】
また、支持体をチューブ状とすれば、チューブ内に冷媒を通して支持体を冷却し、支持体の発熱を防止することもできる。
【００５７】
また、支持体を冷却しようとする場合、冷媒は、空気、窒素、またはアルゴン等の不活性気体や、それらの混合気体を使用でき、水、油等の液体を使用できる。これら冷媒を使用する際は、高温によって発火等の危険性のないものを、さらに価格を考慮して選択する必要がある。
【００５８】
炉内面で使用する場合のワッシャ状支持具２の形状、大きさは特に制限されないが、ワッシャ状支持具２が円板状であれば、直径が小さすぎるとワッシャ状支持具と接する部分の断熱部材に荷重がかかりすぎるため、直径２０〜８０ｍｍ程度が好ましい。
【００５９】
また、断熱部材の外側と、金属製ケーシング及び導波管の間には、空間を設けて空気流を自然対流させて、支持体を自然冷却することが好ましい。
【００６０】
次に断熱部材について説明する。
【００６１】
本発明に使用する断熱部材としては、アルミナ繊維等の無機繊維と、無機バインダー、必要に応じて無機粉体、有機結合材からなる断熱部材で、例えば、アルミナ繊維、アルミナシリカ繊維の１種または両方を水中で分散させ、アルミナ粉を加えてスラリーとしたものを、吸引用の成形モールドによって平板状に真空成形した平板状成形体が好適である。また、作製時に必要に応じ、少量の有機バインダーを使用することもできるが、その場合は成形後に加熱処理して有機バインダーを焼失させることが必要である。ここで、一般に、アルミナ繊維とは、Ａｌ_２Ｏ_３含有率が７０％以上で残部がＳｉＯ_２である、アルミナ及び／またはムライトの結晶質繊維を言い、アルミナシリカ繊維とは、Ａｌ_２Ｏ_３含有率が４６〜５４％で残部がＳｉＯ_２である非晶質無機繊維を言う。
【００６２】
また、被加熱物の処理温度が１０００℃程度であるような、処理温度の低い炉では、アルミナシリカ繊維、無機バインダー、必要に応じ少量の有機バインダーを加えてスラリーとしたものをモールドで成形して平板状成形体としたものが好適である。この際も、有機バインダーを使用した場合は、成形後に有機バインダーを消失させることが必要である．
さらに、上記の如きスラリーの水分量を少なく調整し、モールドを用いてスタンプ成形することによって平板状成形体を作製してもよい。
【００６３】
また、断熱部材として無機繊維ブロックを使用することもできる。無機繊維ブロックは、アルミナ繊維等のブランケットまたはマットを積層して、ブロック状に構成したものである。無機繊維ブロックは、例えば、アルミナ繊維、アルミナシリカ繊維の１種または両方からなるブランケットまたはマットを、同じ大きさに切断して小片とし、これらの小片を積層して積層体とするか、または、細長いブランケットまたはマットを葛折りにして積層体とし、この積層体を圧縮し、バンド締めや縫製によって作製する。無機繊維の構成材であるブランケット及びマットは、繊維が結合材なしに絡み合う状態なので、柔軟性があり、外部からの力に対し復元力を有する。従って、これらブランケットまたはマットで構成された無機繊維ブロックも、柔軟性があり、復元力を有する。
【００６４】
無機繊維ブロツクは、閉空間（炉内）の天井部分の断熱部材として好適である。無機繊維ブロックは前記した平板状成形体に比べ、嵩密度が８０〜２００ｋｇ／ｍ^３と小さく、断熱部材としての重量を軽くでき、支持体が天井部分の断熱部材の荷重を支持する際に、断熱部材にかかる負担が軽減できる。
【００６５】
１０００℃以上で使用する高温用マイクロ波加熱炉用に無機繊維ブロックを使用する場合は、無機繊維ブロックと平板状成形体を組み合わせて使用する。
【００６６】
その理由は、以下の通りである。即ち、炉内が１０００℃以上の高温になってくると、熱の伝導は輻射によって行われる割合が大きくなる。無機繊維ブロックは、繊維が結合材なしに絡み合っている状態で、その嵩密度は８０〜２００Ｋｇ／ｍ^３と小さいため、高温時には、輻射によって外側（炉外側）に熱を逃がしやすく、炉内温度が上がりにくい。一方、平板状成形体は、その嵩密度が２２０〜１０００Ｋｇ／ｍ^３と、無機繊維ブロックに比べ大きく、輻射によって熱を逃がしにくい。従って、無機繊維ブロックを使用する場合は、無機繊維ブロックと平板状成形体を組み合わせることで、効率のよい加熱が行える。
【００６７】
また、複数の断熱部材は、支持体で貫通した形で一体（ユニット）とすることができる。この場合、支持体は、短くてよく、例えば、少なくとも隣り合う断熱部材を支持して一体とすることができる程度の長さの短尺支持体が適している。支持体の長さは、一体としたい断熱部材の大きさや数量に応じて決めることができる。
【００６８】
天井部分の断熱部材は、前述の平板状成形体や、無機繊維ブロックが好適に使用できる。
【００６９】
天井部分の断熱部材として、平板状成形体を用いる場合は、平板状成形体の広い面を炉内面として、厚さ方向に積層（床に垂直な方向に積層）して用いることができる。この場合、断熱部材の支持構造としては、第１又は第２の支持構造が好適である。
【００７０】
また、平板状成形体は、端面を炉内側に向けて、厚さ方向に積層（水平方向に積層）して天井部分の断熱部材とすることができる。この場合は、断熱部材の支持構造としては、第３の支持構造が好適である。
【００７１】
さらに、天井部分の断熱部材として無機繊維ブロックを使用する場合、例えば、隣接する無機繊維ブロック同士を、短尺の支持体をブロックに貫通してユニット化し、ユニット化した無機繊維ブロックを第１又は第２の支持構造によって支持できる。また、短尺の支持体は用いずに、第３の支持方法によって支持することもできる。
【００７２】
また、前述のように、１０００℃以上で使用するマイクロ波加熱炉に、無機繊維ブロックを使用する場合には、平板状成形体を併用する。この場合は、平板状成形体の広い面が炉内面となるように配置し、その外側に無機繊維ブロックを配置して、第１、第２、第３何れかの支持構造で支持することが好適である。この際、平板状成形体と無機繊維ブロックは無機接着材で接着してもよい。
【００７３】
側壁部分を構成する断熱部材は、前述の平板状成形体や、無機繊維ブロックが好適に使用でき、天井部分と同様に、１０００℃以上で使用するマイクロ波加熱炉に、無機繊維ブロックを使用する場合には、平板状成形体を併用する必要がある。
【００７４】
この場合、平板状成形体の広い面が炉内面となるように配置し、その外側に無機繊維ブロックを配置する。無機繊維ブロックと平板状成形体は、無機接着材で接着する、または短尺の支持体とワッシャ状支持具で支持（接合）することが好適である。
【００７５】
本発明においては、天井部分と側壁部分との接合関係は、前述の実施例に限らず、種々のものを採用することができる。たとえば、図示例では、天井部分のエッジ部が中心部と同じ厚みで平坦になっているが、天井部分のエッジ部の厚みを変化させたり（たとえば厚くしたり）、エッジ部分の形状を変化させたり（たとえばＬ字形に曲げたり）することも可能である。
【００７６】
【実施例】
断熱部材として、アルミナ繊維、無機粉体、結合材を水で分散させたスラリーをモールドを用いて真空成形して得られた平板状成形体を使用した。
【００７７】
側壁部分は、平板状成形体（厚さ７０ｍｍ）を、その厚さ方向に積層し、積層方向が床と平行な方向になるようにして構成した。さらに、側壁部分の外側（金属製ケーシング側）の面に接するように、外径３５ｍｍのアルミナチューブを断熱部材の積層方向と同方向に配して側壁部分を支持した。また、アルミナチューブは、金属製ケーシングの一方の側面から対面する他方の側面に渡し、アルミナチューブの端部は金属製ケーシングに開けた穴に差し込んで固定した。さらにアルミナチューブの一端から冷媒として空気を流し、他端に抜けるようにしてアルミナチューブを冷却した。
【００７８】
天井部分は、断熱部材として、上記平板状成形体（厚さ４０ｍｍ）を用いた。平板状成形体を厚さ方向に積層し、積膚する方向が床と平行となるように構成した。（平板状成形体の端面が炉内面となる）
天井部分の支持構造としては、第３の支持構造を用いた。
【００７９】
吊り具支持体として、内径２８ｍｍ、外径３５ｍｍ、長さ４１０ｍｍのアルミナチューブを使用した。吊り具支持体の上端から２５ｍｍ、及び下端から２５ｍｍの位置を中心として、直径１５ｍｍの孔を径方向に貫通孔を１ヶづつ設けた。上端部の孔は、金属製ケーシングに固定したホルダー、及びアルミナピン（内径９ｍｍ、外径１３ｍｍ、長さ５０ｍｍ）によって吊り具支持体を支持するための、アルミナピンを差し込むための孔とし、下端の孔は、天井部分の断熱部材を水平方向に貫通する長尺のアルミナチューブ支持体が通る孔とした。
【００８０】
吊り具支持体は、天井の断熱部材の所定位置で、金属製ケーシング側から約６０ｍｍの深さまで断熱部材に孔加工を施して、吊り具支持体の下端部を差し込み、アルミナチューブ支持体（内径９ｍｍ、外径１３ｍｍ、長さ７９０ｍｍ）が、天井の断熱部材を水平方向に貫通し、吊り具支持体の下端部の孔を通って断熱部材を支持するようにした。
【００８１】
吊り具支持体の他端部（上端部）は、金属製ケーシングに設けた直径５０ｍｍの孔を通って、金属製ケーシングに設けた孔の外側部分に固定された円筒状ホルダーと、吊り具支持体の上端部に設けた貫通孔に差し込まれたアルミナピンとで支持するようにした。
【００８２】
床部分は、上記平板状成形体（厚さ４０ｍｍ）を平板状成形体の広い面を炉内側にして、３層積層して用いた。
【００８３】
これら側壁、天井、床の、各断熱部材で囲まれた閉空間は、幅８２０ｍｍ、高さ４４０ｍｍ、奥行き４４０ｍｍであった。
【００８４】
金属製ケーシングは、天井、側壁、床の断熱部材を囲むように（６面）配した。さらに側壁部分の断熱部材及び天井部分の断熱部材と、金属製ケーシングとの間は、約２００ｍｍの間隔を設け、空気流の自然対流で冷却できる構造とした。
この高温用マイクロ波加熱炉で、被加熱物として陶磁器材料を１３００℃で加熱したところ、断熱部材で囲まれた閉空間は変形することなく安定に陶磁器材料を加熱できた。また、陶磁器材料には、歪みや割れを生じることなく、支持体は、変形することなく、断熱部材を安定に固定、支持できた。
【００８５】
【発明の効果】
本発明の、高温用マイクロ波加熱炉断熱材の支持構造によれば、高温用マイクロ波加熱炉において、炉の運転中に断熱部材の加熱時の膨張、降温時の収縮、特に天井部分の断熱部材の動きによって、側壁部分の断熱部材が外側（炉外側）に押されることがなく、炉の運転中に、断熱部材で構成する閉空間が変形することを防止し、炉の運転を安定に行うことができる。
【図面の簡単な説明】
【図１】本発明による高温用マイクロ波加熱炉の断熱部材の支持構造を示す概念図である。
【図２】本発明で使用する吊り具支持体の例を示す図である。
【図３】本発明による高温用マイクロ波加熱炉の断熱部材の支持構造を示す概念図である。
【図４】本発明による高温用マイクロ波加熱炉の断熱部材の支持構造を示す概念図である。
【図５】吊り具支持体の上端部を筒状ホルダーと、ピンによって支持した例の概念図である。
【図６】吊り具支持体の上端部をネジ加工し、吊り具支持体をワッシャ状支持具と螺合して支持した例の概念図である。
【図７】吊り具支持体の下端部をネジ加工し吊り具支持体をワッシャ状支持具と螺合して支持した例の概念図である。
【図８】本発明による高温用マイクロ波加熱炉全体の概念図である。
【符号の脱明】
１吊り具支持体
２ワッシャ状支持具
３チューブ状若しくは棒状支持体
４筒状ホルダー
５ピン
６断熱部材
７被加熱物
８棚板
９マイクロ波発振器
１０導波管
１１金属製ケーシング
１２高温用マイクロ波加熱炉[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a support structure for a heat insulating member in a high-temperature microwave heating furnace, and more specifically, for example, in a high-temperature microwave heating furnace, a ceiling portion of a heat insulating member that forms a closed space so as to surround an object to be heated. Regarding the support structure.
[0002]
[Related technologies]
In microwave heating, microwave power is absorbed by a dielectric and self-heats from inside the dielectric (heated object).
[0003]
For this reason, compared with the conventional heating method using heat conduction or radiation, which uses gas, electric resistance, or the like as a heat source, microwave heating enables rapid heating and has high thermal efficiency, so that heat treatment is performed in a short time. be able to.
[0004]
Applying this principle, microwave heating is widely used as an apparatus for heating and vulcanizing rubber or bonding and drying wood.
[0005]
In addition to these low-temperature applications, Patent Document 1 describes a microwave heating furnace for firing ceramics and ceramics as a high-temperature application, and Patent Document 2 describes a firing furnace that performs firing using a microwave oven. I have. In such a high-temperature application, it is necessary to surround the object to be heated with a heat insulating material so as not to dissipate the heat generated by the self-heating of the object to be heated.
[0006]
[Patent Document 1] Japanese Patent Publication No. 59-25937
[0007]
[Patent Document 2] Japanese Patent Application Laid-Open No. 7-318262
The microwave heating furnace for high temperature use mainly consists of a microwave oscillating device, a waveguide which is a microwave oscillating port, a fan for dispersing microwaves, a casing for preventing microwave leakage, and a heat insulating material. .
[0008]
The conventional microwave heating furnace disclosed in the above publication for high temperature use has been small. Therefore, when constructing the closed space (space in the furnace) surrounding the object to be heated with the heat insulating material, it was possible to use a single heat insulating material in which the side wall portion and the ceiling portion were substantially formed into a body. As a result, a support for supporting the heat insulating material was not particularly required. In other words, the integrally formed heat insulating material was able to stand mechanically and stably on its own.
[0009]
However, when the furnace is enlarged, a large closed space made of a heat insulating material is required. In order to construct such a wide space, it is necessary to form a side wall portion and a ceiling portion by combining a plurality of heat insulating materials. As a result, it became necessary to support and fix a plurality of heat insulating materials.
[0010]
On the other hand, in general, in a conventional large heating furnace using a gas, electric resistance, or the like as a heat source, a rod-shaped or claw-shaped metal support is used as an outer frame as a method of fixing the heat insulating member. A method of fixing a heat insulating material to a strong metal casing is generally used.
[0011]
On the other hand, microwaves are absorbed by a part of a metal to generate heat, but have a property of being reflected by most of the metal. This property is used as needed. For example, in a general electronic cooker or a heating furnace using microwaves as a heat source, the property that microwaves are reflected by metal is used to surround the cooker and the entire furnace with metal so that microwaves do not leak outside the furnace. To prevent danger.
[0012]
Furthermore, there is a point to be considered in performing microwave heating at a high temperature. That is, a) The object to be heated must be covered with a heat insulating member, and the microwave oscillator and the waveguide must be arranged outside the heat insulating member. This is because the use of a heat insulating member confines the high heat generated from the object to be heated in a closed space covered by the heat insulating member, keeping the object to be heated at a high temperature, and keeping the outside of the heat insulating member at a low temperature, and using microwaves. This is to prevent the oscillator and the waveguide from being damaged. Therefore, the object to be heated, the heat insulating material, the oscillator, and the waveguide are provided in this order from the inside.
[0013]
b) During operation of the furnace, the closed space formed by the heat insulating member needs to be stable without being greatly deformed. If the closed space formed by the heat insulating member is greatly deformed, heat from the inside of the furnace (inside of the closed space) leaks from a gap in the heat insulating member, or the closed space itself collapses, which is dangerous.
[0014]
c) On the other hand, the microwave needs to be oscillated from the oscillator through the waveguide, transmitted through the outer heat insulating member constituting the closed space, and efficiently reach the innermost heated object. Therefore, it is necessary to avoid, as much as possible, at least between the waveguide and the object to be heated, a member that obstructs the object or a member that melts and loses its original function. For example, a metal plate, a support, or the like cannot be arranged and used as it is.
[0015]
d) The heat insulating member needs to be made of a material that does not hinder the heat generation of the object to be heated by the microwave, that is, a material that has excellent permeability to the microwave. This is because if the heat insulating member absorbs a large amount of microwaves, the microwaves do not reach the object to be heated, and the object to be heated hardly generates heat. In other words, the heat insulating member, the support, and the adhesive need to have the same dielectric loss as that of the object to be heated or smaller than that of the object to be heated.
[0016]
e) To ensure safety for the human body, it is necessary to prevent microwaves from leaking out of the furnace. That is, a metal casing that covers at least the outside of the heat insulating member and creates a closed space is required.
[0017]
Here, means relating to a) and d) have already been proposed in Japanese Patent Application No. 2001-339162.
[0018]
In addition, the present inventor has already disclosed, in Japanese Patent Application Nos. 2002-033992, 2002-034045, and 2002-034801, a closed space (enclosed in the furnace) surrounding an object to be heated. ) Is constructed with a plurality of heat insulating members and a support made of a material having a dielectric loss equal to or smaller than that of the object to be heated.
[0019]
[Problems to be solved by the invention]
However, when the furnace is upsized, if a fired refractory or a ceramic fiber board is used as a heat insulating member at a ceiling or a portion where the ceiling and the side wall are in contact with each other, for example, by making the ceiling an arch structure, the heat insulating member is used during the operation of the furnace. Due to expansion during heating and shrinkage during cooling, particularly the movement of the heat insulating member in the ceiling, the heat insulating member in the side wall is pushed outward (outside the furnace), and in the pressed state, the weight of the heat insulating member in the ceiling is increased. However, the closed space formed by the heat insulating member is deformed, and the furnace cannot be operated stably. In particular, when the size of the furnace is increased, the weight of the heat insulating member in the ceiling increases, and the heat insulating member forming the closed space is more likely to be deformed.
[0020]
The object of the present invention is that, during operation of the furnace, due to the expansion and contraction movement of the heat insulating member of the ceiling portion, the heat insulating member of the side wall portion is deformed, and thereby, the closed space surrounded by the heat insulating member is not deformed, An object of the present invention is to provide a heat insulating structure of a high-temperature microwave heating furnace in which the furnace can be operated stably.
[0021]
[Means for Solving the Problems]
The inventor of the present invention has intensively studied to solve the above-mentioned problems in the microwave heating furnace for high temperature, and as a result, has improved the method of supporting the ceiling portion of the microwave heating furnace for high temperature, and in particular, the heat insulating member of the ceiling portion has been improved. Independently of the side wall insulation, the support of the bulk of the ceiling part is supported by a support of a material whose dielectric loss is the same as or smaller than the object to be heated, and preferably the insulation of the side wall part The present inventors have found that the problem can be solved by preventing the load of the heat insulating member in the ceiling portion from being substantially applied to the member, and completed the present invention.
[0022]
An example of the solution of the present invention is a support structure for a high-temperature microwave heating furnace heat insulating member described in each claim.
[0023]
Here, preferably, the casing is made of metal, located outside the waveguide, to prevent microwaves from leaking out of the furnace, and for supporting and fixing the support. is there.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention is an improvement of a supporting structure of a heat insulating member on a ceiling portion of a high-temperature microwave heating furnace using a microwave as a heating source.
[0025]
Usually, an object to be heated, a heat insulating member and a support, and a metal casing are arranged in this order from the inside of the furnace. A waveguide, which is a microwave oscillating port, is provided in a metal casing, and microwaves are emitted from the waveguide toward an object to be heated. A closed space is formed by using a heat insulating member in the form of a wall inside the metal casing so as to surround the object to be heated, and the heat insulating member is supported by a support.
[0026]
In the supporting structure of the microwave heating furnace for high temperature according to the present invention, particularly, the heat insulating member of the ceiling portion is insulated at the side wall portion by a support of a material having the same dielectric loss as the object to be heated or smaller than that of the object to be heated. Independently of the members, the bulk of the ceiling portion is supported, preferably such that the thermal insulation of the ceiling portion is substantially free of the load of the thermal insulation of the ceiling portion. In this way, during operation of the furnace, it is possible to prevent the closed space (furnace) defined by the heat insulating member from being deformed due to heat fluctuation, for example, expansion and contraction of the heat insulating member, particularly, the heat insulating member in the ceiling portion. , So that the furnace can be operated stably.
[0027]
A preferred support structure of the present invention will be described with reference to the drawings.
[0028]
First, the support structure of the heat insulating member on the ceiling will be described.
[0029]
FIG. 1 is a conceptual diagram of the first support structure. The first supporting structure of the heat insulating member of the ceiling portion includes a heat insulating member constituting the ceiling portion of the closed space (inside the furnace), a hanging member support 1, a washer-shaped support 2, a tube-shaped or rod-shaped support 3, and the like. It is a structure to support using. As a material for these support members, a material having a small dielectric loss, for example, a sintered body of alumina is preferable. The hanging member support 1 is preferably, for example, one in which the upper end is provided with a hook shape, and the lower end is provided with a screw processing for fixing the washer-shaped supporting member. There is no particular limitation as long as the hanging support 1 can be fixed, such as by fixing the hanging support 1 and the washer-shaped support 2 so as to fit. The hanging tool support 1 has a hook-shaped upper end hooked on a tube-shaped or rod-shaped support 3, and a lower end vertically penetrates a heat insulating member. Fix and support the heat insulating member.
[0030]
Further, the hanging member support 1 may be supported through a tube-shaped or rod-shaped supporting member 3 in a horizontal through hole provided in the hanging member support 1 without forming the upper end portion in a hook shape.
[0031]
The tube-shaped or rod-shaped support body 3 is horizontally supported from one side of the metal casing 11 to the other side, and is supported and fixed at a portion in contact with the metal casing 11. In this case, the tube-shaped or rod-shaped support 3 is suitably long, which can at least pass the distance between both side surfaces of the metal casing 11 described above.
[0032]
FIG. 2 is a conceptual diagram of the hanger support 1 having a hook-shaped upper end.
[0033]
Next, the second support structure of the heat insulating member in the ceiling portion will be described.
[0034]
FIG. 3 is a conceptual diagram of the second supporting method.
[0035]
The second support structure does not use a tube-shaped or rod-shaped support, and uses the cylindrical holder 4 and the pin 5 on the upper end of the hanging tool support 1 on the outside of the upper surface of the metal casing 11 or a washer-shaped support. The structure is such that the supporting member 2 is used for supporting, and the lower end is supported by the washer-shaped supporting member 2 on the inner surface of the furnace of the heat insulating member 6.
[0036]
In this case, for example, as shown in FIG. 5, the upper end portion of the suspender support 1 penetrating the heat insulating member 6 is projected from a hole provided in the metal casing 11, and the projecting suspender support 1 is provided with a cylinder. A structure in which a rod-shaped pin 5 is inserted into a through-hole provided on the side surface near the upper end of the hanging member support 1 and a through-hole provided on the side surface of the cylindrical holder 4 so as to support each other. It is suitable.
[0037]
Further, as shown in FIG. 6, instead of using the cylindrical holder 4, the hanging support 1 having a threaded upper end and the washer-shaped support 2 having a threaded through hole are screwed or suspended. The tool support 1 and the washer-shaped support 2 are processed so as to be fitted and supported.
[0038]
On the other hand, the hanging member support 1 penetrates the heat insulating member 6 in the vertical direction and fixes the washer-shaped supporting member 2 to the lower end of the hanging member support 1 on the inner surface of the furnace of the heat insulating member 6. Support. Here, as shown in FIG. 7, the washer-shaped support 2 is fixed by using a hanging support 1 having a threaded end and a washer-shaped support 2 having a threaded through hole. It is preferable that the suspension support 1 and the washer-shaped support 2 are processed so as to be fitted and supported.
[0039]
Next, a third support structure of the heat insulating member in the ceiling portion will be described.
[0040]
FIG. 4 is a conceptual diagram of the third support structure. The third support structure of the heat insulating member in the ceiling portion allows the tubular or rod-shaped support member 3 to pass through the heat insulating member 6 in the ceiling portion in the horizontal direction. The supporting and hanging member support 1 has an upper end projecting from the metal casing 11 and being supported by the holder 4 and the pin 5 or by the washer-shaped support 2 on the outside of the metal casing 11, thereby providing a ceiling. A portion of the heat insulating member 6 is supported. Further, the tube-shaped or rod-shaped support body 3 which horizontally penetrates the heat-insulating member 6 at the ceiling may be supported at both ends by side surfaces of a metal casing as necessary. Further, the lower end of the hanging member support 1 may have a hook shape to support the tube-shaped or rod-shaped support 3. Alternatively, the tube-shaped or rod-shaped support 3 may be supported by passing the tube-shaped or rod-shaped support 3 through a through hole provided in the lower end portion of the hanger support 1 in the horizontal direction.
[0041]
In this case, the tube-shaped or rod-shaped support 3 only needs to be long enough to support the heat insulating member 6 on the ceiling in the horizontal direction.
[0042]
The number of the hanger support 1, the tube-shaped or rod-shaped support 3 may be arbitrarily increased or decreased according to the size of the furnace, but the hanger support 1 may be in the form of a tube or a bar at an interval of about 200 to 400 mm. The rod-shaped supports 31 are preferably arranged at intervals of about 300 to 500 mm.
[0043]
Next, a support structure of the heat insulating member on the side wall portion will be described.
[0044]
In the present invention, since the heat insulating member of the ceiling portion is preferably supported independently of the side wall portion, the heat insulating member of the side wall portion is safe from movement due to expansion and contraction of itself and movement due to external force such as earthquake. What is necessary is just to provide a support that does not cause large deformation. It is preferable that the heat insulating member constituting the side wall portion is supported by the support by extending the support from one side surface of the metal casing located on the opposing surface to the other opposing side surface.
[0045]
Further, preferably, the support is supported and fixed at a portion in contact with the metal casing. In this case, a long support is suitable for the support as described above. It is sufficient that at least a part of the long support for supporting the heat insulating member constituting the side wall portion supports the outside or the surface of the heat insulating member. Further, the heat insulating member may be penetrated and supported by the support, or the adjacent heat insulating members may be supported by penetrating each other by the short support.
[0046]
FIG. 8 is a conceptual diagram of the entire high-temperature microwave heating furnace.
[0047]
As described above, it is preferable that the heat insulating member of the ceiling portion is supported independently of the heat insulating member of the side wall portion so that the load of the heat insulating member of the ceiling portion is not substantially applied to the heat insulating member of the side wall portion.
[0048]
In this way, during operation of the high-temperature microwave heating furnace, the closed space (inside the furnace) formed by the heat insulating member can be prevented from being deformed by the expansion and contraction of the heat insulating member, and can be stably performed. Furnace operation can be performed.
[0049]
The hanger support, the tube-like or rod-like support, and the washer-like support that are disposed inside the metal casing are safely disposed as described above. Therefore, it is excellent in microwave permeability and heat resistance, has high-temperature strength, and is preferably a material that can be easily formed and processed, and a nonmetallic and inorganic material is preferable.For example, alumina, mullite, steatite, Preferred are refractories made of zircon, cordierite, silica, quartz, silicon carbide, silicon nitride and the like.
[0050]
In a high-temperature microwave heating furnace, the properties of the material used and the object to be heated with respect to microwaves are important. When considering the transmission, reflection and absorption of microwaves with respect to a material, a material having excellent microwave permeability has, in other words, a property that is difficult to reflect and absorb microwaves. One factor that expresses this property is dielectric loss.
[0051]
Materials with high dielectric loss tend to absorb microwaves. As a result, the calorific value of the material increases. Therefore, in a high-temperature microwave heating furnace, the temperature is higher than that of the object to be heated, and the required strength cannot be maintained at a high temperature. As a result, accurate temperature control of the object to be heated becomes difficult. Further, the microwaves are absorbed by these materials before reaching the object to be heated, and the heat generation efficiency of the object to be heated deteriorates.
[0052]
That is, in the high-temperature microwave heating furnace, it is preferable that the dielectric loss of the support or the like supporting the heat insulating member is equal to or smaller than that of the object to be heated. For example, when the object to be heated is mullite, the support or the like is preferably made of mullite or alumina, and when the object to be heated is alumina, the support or the like is preferably made of alumina.
[0053]
The hanging member support used in the present invention is preferably in the shape of a rod or a tube, and the end is preferably in a shape suitable for support, such as a hook or a screw, if necessary. In the case where the cross section of the rod-shaped or tube-shaped portion of the hanging member support is, for example, circular, the diameter is preferably about 5 to 20 mm for a rod and about 20 to 40 mm for an outer diameter for a tube.
[0054]
The tubular or rod-shaped support used mainly in the horizontal direction in the present invention may have any shape, such as cross-sectional shape, cross-sectional width, and diameter. However, if the width and the diameter are too small, the strength of the support is insufficient. If the width and the diameter are too large, the amount of the microwave absorbed by the support increases, and the object to be heated cannot be efficiently heated. This is the same for the hanger support.
[0055]
The support is most preferably in the form of a tube in consideration of availability of materials, price, workability, and workability. In the case of a tubular or rod-shaped support mainly used in the horizontal direction, when the cross section is, for example, circular, the diameter is preferably about 10 to 40 mm.
[0056]
Further, if the support is formed in a tube shape, the support can be cooled by passing a cooling medium through the tube, and heat generation of the support can be prevented.
[0057]
When the support is to be cooled, the refrigerant may be an inert gas such as air, nitrogen, or argon, or a mixed gas thereof, or a liquid such as water or oil. When using these refrigerants, it is necessary to select a refrigerant having no danger of ignition or the like due to high temperature in consideration of the price.
[0058]
The shape and size of the washer-like support 2 when used on the inner surface of the furnace are not particularly limited. However, if the washer-like support 2 is disc-shaped, if the diameter is too small, heat insulation of a portion in contact with the washer-like support is performed. Since a load is excessively applied to the member, the diameter is preferably about 20 to 80 mm.
[0059]
In addition, it is preferable that a space is provided between the outside of the heat insulating member and the metal casing and the waveguide to allow natural convection of the air flow to naturally cool the support.
[0060]
Next, the heat insulating member will be described.
[0061]
As the heat insulating member used in the present invention, an inorganic fiber such as an alumina fiber and an inorganic binder, if necessary, an inorganic powder, an insulating member made of an organic binder, for example, alumina fiber, one kind of alumina silica fiber or A plate-like molded product obtained by dispersing both in water, adding an alumina powder to form a slurry, and vacuum-molding the slurry into a plate shape by a molding mold for suction is preferable. In addition, a small amount of an organic binder can be used as needed at the time of fabrication. In that case, however, it is necessary to perform a heat treatment after molding to burn off the organic binder. Here, generally, the alumina fiber is Al ₂ O ₃ The content is 70% or more and the balance is SiO ₂ Alumina and / or mullite crystalline fibers are referred to as alumina silica fibers. ₂ O ₃ The content is 46-54% and the balance is SiO ₂ Is an amorphous inorganic fiber.
[0062]
Further, in a furnace having a low processing temperature such that the processing temperature of the object to be heated is about 1000 ° C., a slurry obtained by adding alumina silica fiber, an inorganic binder, and a small amount of an organic binder as necessary is molded in a mold. It is preferable to use a flat molded body. At this time, when an organic binder is used, it is necessary to eliminate the organic binder after molding.
Further, a flat molded body may be produced by adjusting the water content of the slurry as described above to a small value and stamp-molding using a mold.
[0063]
In addition, an inorganic fiber block can be used as the heat insulating member. The inorganic fiber block is formed by laminating a blanket or a mat of alumina fiber or the like to form a block. Inorganic fiber block, for example, alumina fiber, one or both of alumina silica fiber blanket or mat, cut into the same size into small pieces, these pieces are laminated to form a laminate, or, An elongated blanket or mat is folded into a laminate, and the laminate is compressed and manufactured by banding or sewing. Blankets and mats, which are constituents of inorganic fibers, are flexible and have a restoring force against external force because the fibers are entangled without a binder. Therefore, the inorganic fiber block composed of these blankets or mats is also flexible and has a restoring force.
[0064]
The inorganic fiber block is suitable as a heat insulating member for a ceiling portion of a closed space (in a furnace). The inorganic fiber block has a bulk density of 80 to 200 kg / m, as compared with the above-mentioned flat molded body. ³ Therefore, the weight of the heat insulating member can be reduced, and the load on the heat insulating member can be reduced when the support supports the load of the heat insulating member on the ceiling.
[0065]
When using an inorganic fiber block for a high-temperature microwave heating furnace used at 1000 ° C. or higher, a combination of the inorganic fiber block and a flat molded body is used.
[0066]
The reason is as follows. That is, when the temperature inside the furnace becomes 1000 ° C. or higher, the rate of heat conduction by radiation increases. The inorganic fiber block has a bulk density of 80 to 200 kg / m in a state where the fibers are entangled without a binder. ³ Therefore, at high temperatures, heat is easily released to the outside (outside of the furnace) by radiation, and the temperature inside the furnace is unlikely to rise. On the other hand, the flat molded body has a bulk density of 220 to 1000 kg / m. ³ Is larger than the inorganic fiber block, and it is difficult to release heat by radiation. Therefore, when the inorganic fiber block is used, efficient heating can be performed by combining the inorganic fiber block and the flat molded body.
[0067]
Further, the plurality of heat insulating members can be integrated (unit) in a form penetrated by the support. In this case, the support may be short, and for example, a short support having a length that can support and integrate at least the adjacent heat insulating members is suitable. The length of the support can be determined according to the size and quantity of the heat insulating member to be integrated.
[0068]
As the heat-insulating member of the ceiling portion, the above-mentioned flat molded body or inorganic fiber block can be suitably used.
[0069]
When a flat molded body is used as the heat insulating member of the ceiling portion, the flat molded body can be used by laminating in the thickness direction (laminated in the direction perpendicular to the floor) using the wide surface of the flat molded body as the furnace inner surface. In this case, the first or second support structure is suitable as a support structure for the heat insulating member.
[0070]
In addition, the flat molded body can be laminated in the thickness direction (laminated in the horizontal direction) with the end face facing the inside of the furnace to be used as a heat insulating member for the ceiling portion. In this case, the third support structure is suitable as a support structure for the heat insulating member.
[0071]
Furthermore, when an inorganic fiber block is used as a heat insulating member of the ceiling portion, for example, adjacent inorganic fiber blocks are unitized by penetrating a short support into the block, and the unitized inorganic fiber block is first or second. 2 can be supported. Further, it is also possible to support by a third supporting method without using a short supporting body.
[0072]
Further, as described above, when an inorganic fiber block is used in a microwave heating furnace used at a temperature of 1000 ° C. or higher, a flat molded body is used in combination. In this case, it is possible to arrange the flat molded body so that the wide surface thereof becomes the inner surface of the furnace and arrange the inorganic fiber block outside thereof so as to be supported by any of the first, second, and third support structures. It is suitable. At this time, the flat molded body and the inorganic fiber block may be bonded with an inorganic adhesive.
[0073]
As the heat insulating member constituting the side wall portion, the above-mentioned flat molded body or inorganic fiber block can be suitably used, and, like the ceiling portion, the inorganic fiber block is used in a microwave heating furnace used at 1000 ° C. or higher. In such a case, it is necessary to use a flat molded body together.
[0074]
In this case, the flat shaped body is arranged so that the wide surface of the shaped body becomes the inner surface of the furnace, and the inorganic fiber block is arranged outside thereof. It is preferable that the inorganic fiber block and the flat molded body are bonded with an inorganic adhesive or supported (joined) with a short support and a washer-like support.
[0075]
In the present invention, the joining relationship between the ceiling portion and the side wall portion is not limited to the above-described embodiment, and various types can be adopted. For example, in the illustrated example, the edge portion of the ceiling portion is flat with the same thickness as the center portion, but the thickness of the edge portion of the ceiling portion is changed (for example, the thickness is increased) or the shape of the edge portion is changed. (E.g., bent into an L-shape).
[0076]
【Example】
As the heat insulating member, a flat molded body obtained by vacuum forming a slurry in which alumina fiber, inorganic powder, and binder were dispersed in water using a mold was used.
[0077]
The side wall portion was formed by laminating a plate-like molded body (thickness: 70 mm) in the thickness direction thereof so that the lamination direction was parallel to the floor. Further, an alumina tube having an outer diameter of 35 mm was arranged in the same direction as the laminating direction of the heat insulating member to support the side wall portion so as to be in contact with the outer surface (the side of the metal casing) of the side wall portion. The alumina tube was passed from one side to the other side of the metal casing, and the end of the alumina tube was inserted and fixed in a hole formed in the metal casing. Further, air was flowed as a refrigerant from one end of the alumina tube, and the alumina tube was cooled so as to escape to the other end.
[0078]
The flat part (40 mm in thickness) was used for the ceiling part as a heat insulating member. The flat molded bodies were laminated in the thickness direction, and the stacking direction was parallel to the floor. (The end face of the flat molded body becomes the furnace inner surface)
The third support structure was used as a support structure for the ceiling portion.
[0079]
An alumina tube having an inner diameter of 28 mm, an outer diameter of 35 mm, and a length of 410 mm was used as a hanger support. Holes having a diameter of 15 mm were provided one by one in the radial direction, centered on positions 25 mm from the upper end and 25 mm from the lower end of the hanging member support. The hole at the upper end is a hole for inserting an alumina pin for supporting a hanging support by a holder fixed to a metal casing and an alumina pin (inner diameter 9 mm, outer diameter 13 mm, length 50 mm). Is a hole through which a long alumina tube support penetrating the heat insulating member in the ceiling portion in the horizontal direction passes.
[0080]
The hanging member support is formed by drilling a hole in the heat insulating member to a depth of about 60 mm from the metal casing side at a predetermined position of the heat insulating member on the ceiling, inserting the lower end portion of the hanging member support, and forming an alumina tube support (inner diameter). 9 mm, an outer diameter of 13 mm, and a length of 790 mm) penetrate the ceiling heat insulating member in the horizontal direction, and support the heat insulating member through a hole at the lower end of the hanging member support.
[0081]
The other end (upper end) of the hanging tool support passes through a 50 mm diameter hole provided in the metal casing, and is fixed to an outer portion of the hole provided in the metal casing. It was supported by an alumina pin inserted into a through hole provided in the upper end of the body.
[0082]
The floor portion was formed by laminating three layers of the above-mentioned plate-like molded product (40 mm thick) with the wide surface of the plate-like molded product inside the furnace.
[0083]
The closed space surrounded by the heat insulating members of the side wall, ceiling, and floor was 820 mm in width, 440 mm in height, and 440 mm in depth.
[0084]
The metal casing was arranged (6 sides) so as to surround the heat insulating members of the ceiling, the side walls, and the floor. Further, a space of about 200 mm was provided between the heat insulating member of the side wall portion and the heat insulating member of the ceiling portion, and the metal casing, and the structure was such that cooling could be performed by natural convection of air flow.
When the ceramic material was heated at 1300 ° C. as an object to be heated in this microwave heating furnace for high temperature, the closed space surrounded by the heat insulating member could be heated stably without deformation. In addition, the ceramic body material was able to stably fix and support the heat insulating member without causing distortion or cracking and without deforming the support.
[0085]
【The invention's effect】
According to the support structure of the microwave heating furnace heat insulating material for high temperature of the present invention, in the microwave heating furnace for high temperature, the expansion of the heat insulating member during the operation of the furnace during the operation of the furnace, the contraction at the time of cooling down, especially the heat insulation of the ceiling portion. Due to the movement of the members, the heat insulating member on the side wall portion is not pushed outward (outside the furnace), and the closed space formed by the heat insulating member is prevented from being deformed during the operation of the furnace, thereby stably operating the furnace. It can be carried out.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram showing a support structure of a heat insulating member of a high-temperature microwave heating furnace according to the present invention.
FIG. 2 is a view showing an example of a hanger support used in the present invention.
FIG. 3 is a conceptual diagram showing a support structure of a heat insulating member of the microwave heating furnace for high temperature according to the present invention.
FIG. 4 is a conceptual diagram showing a supporting structure of a heat insulating member of the microwave heating furnace for high temperature according to the present invention.
FIG. 5 is a conceptual diagram of an example in which an upper end portion of a hanger support is supported by a cylindrical holder and a pin.
FIG. 6 is a conceptual diagram of an example in which an upper end portion of a suspender support is screwed, and the suspender support is screwed and supported with a washer-like support.
FIG. 7 is a conceptual diagram of an example in which a lower end portion of a suspender support is screwed and the suspender support is screwed and supported with a washer-like support.
FIG. 8 is a conceptual diagram of an entire high-temperature microwave heating furnace according to the present invention.
[Decoding of sign]
1 hanging support
2 Washer-like support
3 tubular or rod-shaped support
4 Cylindrical holder
5 pin
6 Insulation members
7 Heated object
8 shelves
9 Microwave oscillator
10 Waveguide
11 Metal casing
12 Microwave heating furnace for high temperature

Claims

In a high-temperature microwave heating furnace using microwaves as a heating source,
A heat insulating member is arranged so as to surround the object to be heated,
The heat insulating member has a side wall portion and a ceiling portion,
The support supports the majority of the weight of the heat-insulating member in the ceiling portion, and the heat-insulating member in the side wall portion is not substantially deformed even if one of the shape and size changes due to heating of the heat-insulating member in the ceiling portion. The supporting structure of the heat insulating member.

A heat insulating member of a ceiling portion is supported by a suspender support vertically penetrating the heat insulating member, and a washer-like support fixed to a lower end portion of the suspender support. The upper end is supported by a tubular or rod-shaped support, and the tubular or rod-shaped support extends from one side of the metal casing to the other side in a horizontal direction and is in contact with the metal casing. The support structure for a heat insulating member according to claim 1, wherein the support structure is supported.

A heat insulating member of a ceiling portion is supported by a suspender support vertically penetrating the heat insulating member, and a washer-like support fixed to a lower end portion of the suspender support. The support structure for a heat insulating member according to claim 1, wherein an upper end portion protrudes from a hole provided in the metal casing and is supported outside the metal casing.

The heat-insulating member of the ceiling portion is supported by a tubular or rod-shaped support that penetrates the heat-insulating member in the horizontal direction at the lower end of the suspender support vertically arranged. The support structure for a heat insulating member according to claim 1, wherein the support member projects from a hole provided in the metal casing and is supported outside the metal casing.

The support structure for a heat insulating material according to any one of claims 1 to 4, wherein the support is made of a nonmetallic and inorganic material.