JP3638908B2 - Combustion plate and infrared burner - Google Patents

Description

燃焼プレートの表面温度測定
燃焼開始後５分が経過した時点で左右各プレート表面中央付近の温度をそれぞれ測定し、その平均値を表面温度とした。
表面温度の測定には、携帯用ディジタル放射温度計（大同特殊鋼製スターサーモＤＳ−０６ＣＦ）を用いた。輻射率を０．５０に設定。
【００３２】
上記の条件のもとで、従来例１とこの発明の実施例１乃至３の場合、燃焼量Ｗを１６７４、２５１０、３３４７、４１８４としたときの表面温度を測定したところ、図８、図９、図１０、表１、表２、表３に示す結果が得られた。先ず、図８は従来例１とこの発明の実施例の燃焼プレート形状で得られる表面温度特性について、燃焼量Ｗと表面温度℃との関係がグラフで示され、表１には燃焼量Ｗ（Ｗ）に対応する各実施例の燃焼プレート形状で得られる表面温度特性と面負荷（ｋＷ／ｍ^２）が表わされている。尚、１６７４Ｗは本実験バーナにおける標準インプットである。
総燃焼量（標準インプット）；Ｗ
面負荷＝Ｗ／プレート面積 ；Ｗ／ｍｍ^２
炎孔負荷＝Ｗ／炎孔総面積 ；Ｗ／ｍｍ^２
標準インプットが１６７４Ｗの場合
面負荷＝１５７ｋＷ／ｍ^２
炎孔負荷＝８４１ｋＷ／ｍ^２
開孔率が２０％を越えるバーナプレート（例えば、山形突起部にも小炎孔が穿設され、小炎孔１．０ｍｍφ、１．２ｍｍφ）では炎孔負荷が８４１ｋＷ／ｍ^２よりかなり小さい（１／２以下）ので、面負荷が１５７ｋＷ／ｍ^２ を越えると、いちはやく逆火を生ずる。また、開孔率を５％以下とすることは成形上困難である。従って、この発明はこの逆火現象を生じないように小炎孔の開孔率を全体として５％〜２０％とする。実験では前記のように、開孔率＝１８．７％としてある。
【００３３】
【表１】

【００３４】
図８、表１の結果において、従来例１とこの発明の実施例１〜３の燃焼プレートとの特性を比較する。
従来例１は、燃焼量を４１８４Ｗまで増加しても燃焼プレートの表面温度は１０１３℃程度までしか上昇しない。すなわち、従来の燃焼プレートでは燃焼量を２〜２．５倍に増大させても表面温度の上昇をそれに追随させて高めることは難しかった。
この発明の実施例１〜３において、燃焼量（面負荷）の増加に伴って、表面温度が上昇した。また、同一燃焼量の時の表面温度は、実施例１から実施例３の順に徐々に増大した。
図８と表１において、従来例１において、３１５ｋＷ／ｍ^２ （燃焼量３３４７Ｗ）以上の面負荷では面負荷増大に伴う表面温度上昇が緩和された。また、面負荷３９３ｋＷ／ｍ^２（燃焼量４１８４Ｗ）に至って表面温度は１０００℃を越えた。
これに対して、本発明の実施例１〜３においてはその面負荷３９３ｋＷ／ｍ^２（燃焼量４１８４Ｗ）において、１１００℃近傍あるいはそれよりはるかに高温に達した。実施例３の実験結果に基づけば、約２５３ｋＷ／ｍ^２ 程度の比較的低い面負荷（燃焼量約２７００Ｗ）において、すでに１１００℃に達したものと理解できる。実施例３では燃焼量４１８４Ｗで表面温度は１１７３℃にまで達した。燃焼面は非常に明るく、ダイヤ部全体が赤熱していた。また、ダイヤ部の溝の深さを深くして行くことによって燃焼量（インプット）を高くした場合においても、火炎の発生はなく、実施例３のプレートでは標準インプットの約２．５倍の燃焼においても火炎の発生は見られなかった。いずれのダイヤ形状でも燃焼量は通常の高温型プレートの燃焼音と同等であった。
【００３５】
従来例１とこの発明の実施例１との対比において、面負荷１５７ｋＷ／ｍ^２（燃焼量が１６７４Ｗ）以下の低負荷時には表面温度には特段の差が生じなかったが、それ以上の高負荷時には差が生じた。
この結果を生ずる理由について、考察するために各々の凹溝部容積および形状に着目する必要がある。
従来例１では溝部の断面形状が矩形で短く、溝部によって矩形に形成される空間容積が小さく、赤熱面積が小さいこと、その溝部で火炎が滞留せず溝部の下流で火炎が形成されることで、プレートの表面温度の上昇は表１、図８に示すように面負荷を増大しても緩やかで低く、１０００度を少し越える程度の表面温度までである。
これに対して、本発明の台形状凹溝３は、火炎の形成および燃焼ガスの滞留、或いは僅かな未燃焼成分が二次空気と混合されることによって燃焼を完結せしめる等のための空間（火袋）として作用する。また、溝部側壁面３ａは燃焼火炎に直接さらされるので、実質的な赤熱部としての役目をする。
実施例１〜３では溝部が深く、台形形状となったため、溝部側壁面積ならびに溝部空間容積が増大したことなどによる相乗効果として、火炎の形成および燃焼ガスの滞留、或いは僅かな未燃焼成分が二次空気と混合されることによって燃焼を完結せしめることができる。
実施例１では本発明の効果は面負荷が或る程度増大した以後において発揮される。すなわち、前記したように面負荷１５７ｋＷ／ｍ^２ では従来例１と大差ないものの、面負荷２３６ｋＷ／ｍ^２ ですでに表面温度が１０００度を越え、さらに面負荷が増大することにより１１００度近くまで上昇させることができた。実施例２、３では、本発明の効果が低負荷域においてすでに発揮された。すなわち、面負荷１５７ｋＷ／ｍ^２ から表面温度が高く、面負荷２３６ｋＷ／ｍ^２ で表面温度が１０００度を越え、面負荷の増大で表面温度が実施例２では１１３３度、実施例３では１１７３度まで上昇させることができた。
【００３６】
従来例１および実施例１の燃焼プレートにおいて、面負荷３９３ｋＷ／ｍ^２ （燃焼量４１８４Ｗ）の高負荷燃焼時の燃焼火炎の状態を真横から観察した。
従来例１では燃焼プレートの凹溝３’の上方に明るい火炎が形成され、立炎が上方に伸びているのが確認された。すなわち、従来の燃焼プレートの凹溝は浅いので、火袋効果は生じず、赤熱面も少なく、凹溝３’の上方（下流）で炎が形成され、立炎が生じる。
これに対して、本発明の実施例１では凹溝３で火炎が滞留して側壁面が赤熱され、火炎を抑えて高温表面燃焼が実現でき、立炎はほとんど見られなかった。本発明による凹溝が好適な火袋効果を奏することが理解される。すなわち、凹溝内で火袋効果で両側の傾斜した側壁面を赤熱し、全体が赤熱するので、赤外線エネルギーが側壁面だけでなく、突起の頂部を含んで全面に火炎を抑えた低い火炎が形成される。
【００３７】
次に、実施例１、３に保護金網を設けない場合と、保護金網を有する場合とで比較する。
実施例１（金網なし）および実施例３（金網なし）の燃焼プレートを用いた場合と、それに保護金網を配したときに得られる表面温度特性を実施例４（金網有り）および実施例５（金網有り）とする。実施例４、５に用いる保護金網は図１０の実施例のように前記実施例のプレートの上面に間隔をおいて設置する。この金網は、燃焼プレート表面への落下物ないし衝撃力など、著しい外的応力を受けた際にも燃焼プレートの破損を防ぐ作用を有するが、その他に、この金網を設置することで、火炎リテンション材の効果を奏することから立炎抑制されること、並びに、二次空気の混合状態が良好になるなどの結果として燃焼プレート表面温度がさらに上昇することなどが、経験上知られている。
図９にはプレート形状と保護金網の相乗効果についての燃焼量Ｗと表面温度℃との関係がグラフで示され、表２に保護金網で得られる表面温度につき、燃焼量Ｗ（Ｗ）に対応する各実施例の燃焼プレート形状で得られる表面温度特性が表わされている。
【００３８】
【表２】

【００３９】
図９、表２の結果において、この発明の実施例１、３、４、５の燃焼プレートとの特性を比較する。
凹溝部の作用によって奏する上記したような燃焼促進効果については、図９（実施例４および実施例５での金網設置の結果）から明らかである。
実施例４および実施例５では、燃焼プレート上方に保護金網を設置したときの表面温度特性を検討した。燃焼プレートは本実験に用いたそれぞれ実施例１および実施例３のものと同じである。
【００４０】
図９と表２において、実施例１（金網無し）と実施例４（金網有り）との表面温度特性の差が、このことを示している。すなわち、金網を載せることにより、金網なしのときより表面温度が高くなり、燃焼量３３４７Ｗで表面温度が１１０５℃であった。金網を載せることによって、火炎の発生も抑えられた。従って、最も優れた燃焼特性を示すダイヤ形状は溝の深さが最大となる実施例３、それに保護金網を配した実施例５の場合である。このダイヤ形状で燃焼プレートを作成するのが最も好ましい。
一方、実施例５（金網有り）においては、実施例３（金網無し）との差が殆ど生じなかった。このことから、実施例４の燃焼プレートでは、上記したような経験上知られている金網の作用に比類する燃焼促進効果のあることが理解される。従って、本発明によれば、金網およびその配設に纏わる部品点数を削減できる。
【００４１】
図１０には炎孔長を７．５ｍｍとしたときの表面温度特性についての燃焼量Ｗと表面温度℃との関係が示され、表３には燃焼量Ｗ（Ｗ）に対応する各実施例の燃焼プレート形状で得られる表面温度特性が表されている。
【００４２】
【表３】

【００４３】
燃焼プレートの凹溝形状が実施例１と同一で、また炎孔長Ｌを前記実施例より短い７．５ｍｍとしたときの表面温度特性を検討した結果である。比較例１は実施例１の炎孔長を７．５ｍｍとした場合の表面温度特性である。
この表３で比較例１の場合には、燃焼量の増大に伴う表面温度上昇は、実施例１に及ばなかった。このことは凹溝を実施例１と同じとしても炎孔長を短くすると、表面温度が低くなり、従来例１の表面温度特性とほぼ似たものとなるので、炎孔長を短くしすぎると効果のないことが判明した。従って、大幅なターンダウンを可能にする赤外線バーナを設計する際には、予混合気の予熱領域を確保する程度に炎孔長を決める必要がある。
その理由を考察するために、実施例１の燃焼プレート内に複数の熱電対を埋設し、プレート内部の温度分布を測定した。その結果を図１１、表４に示す。
【００４４】
【表４】

【００４５】
図１１、表４において、炎孔部最上流（深さ１２．０ｍｍ）から深さ６ｍｍ付近までほとんど温度が上昇せず、深さ６ｍｍより下流側（プレート表面側）で温度は急激に上昇した後、深さ１．５ｍｍよりやや下流地点（表面近傍）で温度が一定となることから、火炎面がこの付近に存在するものと考えられる。これは赤外線バーナに特徴的なプレート内燃焼であると言える。
対流による熱伝達が無い定常状態であれば、プレート内の予混合気の流れ方向の伝熱は略熱伝導によるもののみとなり、均質な平板内の熱伝導と同じく温度勾配は一定になるはずである。しかし、本実験の結果では、温度勾配は一定でない。これは、予混合気への熱伝達が行われているためであると考えられる。予混合気が予熱されることによって、燃焼性が良好となる。
火炎面より上流（予混合気入口側）におけるプレート内での伝熱は、放射を無視すれば、上流方向へはセラミックスによる熱伝導以外に熱の移動はないと考えてよい。炎孔上流側のプレート内ですでに常温になっている所が存在することから、上流方向に伝わった熱量はすべて予混合気の予熱に使われたものと考えられる。
面負荷をさらに増大させると、炎孔内を流れる予混合気の流速が増大し、同時に火炎面はさらに下流側に移動する。面負荷が増大し続けると、やがて、プレート内燃焼状態から付着火炎状態（立炎状態）へ、さらには、剥離火炎状態（ブルーフレーム状態）と移行する。
従って、大幅なターンダウンを可能にする赤外線バーナを設計する際には、予混合気の予熱領域を確保する程度に炎孔長を決定するとともに、高負荷燃焼に伴い火炎面が最下流域まで移動しても、なお火炎がプレート表面部の赤熱に寄与できるような火袋構造を具備することが必要である。
【００４６】
以上の実験よりこの発明の燃焼プレートによれば、１個のバーナによって、ターンダウン比を３／１程度まで拡大することができ、表面温度が約８００度〜１１００度以上の範囲において調整ができる。
さらに、１１００度以上の高温表面を得るための面負荷が、約３１５〜２５０ｋＷ／ｍｍ^２ 程度にまで低減されるために、従来比、約４０〜５５％の燃料が節約でき、同時にＣＯ_２ 発生量を削減できる。
高負荷燃焼時に際しても、立炎が解消されるので、燃焼プレート表面から被加熱物までの距離をこれまで以上に小さくすることができる。これに伴って加熱効率がさらに向上し、結果的に、装置のダウンサイジング（コンパクト化）や、処理時間の短縮化が実現されるなど、燃焼機器の省エネルギー性が増すとともに、燃焼量が可変となるので、設計自由度も拡大する。
【００４７】
図６は前記燃焼プレートを備えたこの発明の赤外線バーナを備えたガスバーナを示す断面図、図７はこの赤外線バーナを複数個備えた焼成装置を示す説明図である。
【００４８】
図６に示すガスバーナでは、バーナ本体１０の上面に前記１又は複数枚の燃焼プレート１をセラミックウール１１を介在して備え、その燃焼プレート１の上面に間隔をおいて、保護金網１２が備えられている。図において、符号１３は混合ガス噴出ノズル、１４はスロート、１５は混合ガス通路、１６は邪魔板、１７は燃焼プレート支持部である。バーナの燃焼プレートには点火棒等で点火するか、点火栓、パイロットバーナ等点火装置を関連して備えで点火する。
この発明の燃焼プレートを備えた赤外線バーナによれば、高負荷燃焼に際して立炎が解消されるので、被加熱物の加熱効率をさらに向上でき、装置のダウンサイジング（コンパクト化）や処理時間の短縮化が実現できる。
なお、前記実施例では、保護金網を備えた場合を示したが、これに限られるものではなく、保護金網は設けなくともよい。
【００４９】
図７において、食品等の焼成装置を示す。この焼成装置はベルトコンベアー２６上に複数のこの発明の赤外線バーナ２１が任意の間隔をおいて平行に設置され、ベルトコンベアー２６上に置かれた食品を移動しながら焼成するものである。図中、符号２２は燃料通路、２３はブロアー、２４はミキサー、２５は熱風ダクト、２６はコンベアー、Ｐ1〜Ｐ5は圧力計、Ｖ1〜Ｖ5はバルブ、Ｇ１〜Ｇ2はガバナである。
従来であれば加熱処理に適した温度勾配となるようにバーナの設置位置（バーナ間隔、高さ）等を検討する必要があったが、本発明によれば、表面温度が広範囲に制御できるので処理に適した昇温曲線が燃焼量の調節によっても容易に設定される。また、高負荷燃焼に際して立炎が解消されるので、バーナ表面から被加熱物までの距離をこれまで以上に小さくすることができ、これに伴いベルトコンベアー上の被加熱物の加熱効率をさらに向上できる。
この発明の燃焼プレートは、ブロアーを使用して強制的に空気を送り込むバーナに使用すると効果がある。
【００５０】
図１２は燃焼プレートの実施例３を示す一部拡大平面図、図１３はこの実施例３の突起部の平面と側面の拡大図、図１４は炎孔部下流域および溝部におけるガス噴出速度と火炎伝播速度とのつり合い状態を示す模式図で、（イ）は実施例６の１３Ａガスの場合、（ロ）は実施例７の１３Ａガスの場合、（ハ）は実施例６のＢＰ３０ガスの場合を示し、図１５は従来例２の突起部の平面と側面の拡大図である。
【００５１】
図１、図１２および図１３において、１は耐火材からなる燃焼プレートで、斜め格子状等格子状に形成された凹溝３と、該凹溝３により側面が形成された多面体形状の多数の上方に延びる山形突起２と、前記凹溝３の底面に形成された多数の小炎孔４が備えられている。燃焼プレート１は、多面体形状に形成された上方に延びる多数の山形突起２と、該山形突起２の側面を形成する凹溝３と、該凹溝３の底面に形成された多数の小炎孔４とが備えられている。
そして、前記凹溝３は、火炎を滞留させるために幅が底面から上方に向かって広がるように形成されている。前記凹溝３は、底面における幅が凹溝全体においてほぼ均一であり、かつ、上端における幅も凹溝全体においてほぼ均一に構成されている。凹溝３は、火炎を滞留させるために幅が底面から上方に向かって広がるように形成され、その側壁面が小炎孔の軸線に対して傾斜角度θに形成される。
実施例の燃焼プレートの多数の山形突起２は四面体形状（菱形）が縦横に配列し、その各山形突起２間に前記形状の凹溝３が形成されている。この凹溝３の底面の幅Ｂは小炎孔４と同じか、或いは僅かに広く形成される。小炎孔４は前記実施例と同じで直径０．７ｍｍφ〜０．９５ｍｍφとして、山形突起部２の交叉部と凹溝３とにほぼ等間隔をおいて複数個形成される。実施例では各山形突起部２の凹溝３の一辺に二個ずつと交叉部に一個ずつが等間隔に設けられている。
前記燃焼プレートに対する凹溝３に穿設する多数の小炎孔４の開孔率は、前記したように５％〜２０％ととして、ガス噴出速度を速くして燃焼位置を炎孔の下流端近傍に伸ばし、ガス噴出速度の上昇と火炎伝播速度とのつり合いを保たせて燃焼させ、ガス噴出による逆火現象を防ぐことができる。
【００５２】
この凹溝３の側壁面は傾斜面として、前記した実施例では、ＬＰＧに対応する場合として、該凹溝の側壁面の傾斜角度θは、前記小炎孔の軸線に対して１０度〜２０度とした。
燃焼速度の速いＬＰＧを想定した場合は、傾斜角度θを２０度以上開くと火炎の滞留効果が減じられるために好ましくないとしたが、その後の試験により次のことが判明した。
すなわち、例えば、ＬＮＧの１３Ａガス、１２Ａガス等燃焼速度の遅い燃料を用いて燃焼量を抑えた状態（低負荷燃焼）で実施例６のプレートを使用した場合、燃焼音が鳴り止まないと言った課題がある。
而して、燃焼速度が遅い１３Ａガス、１２Ａガスの下では、ＬＰＧよりも燃焼火炎が下流側にシフトし易い性格があるため、特に低負荷燃焼の場合においては、溝部の傾斜角度をさらに緩める（２０度以上開く）ことで、混合ガスが細炎孔から噴出する速度（燃焼ガスの流速）がさらに減じられ、火炎面を上流側（炎孔真近）に維持することができるようにする。これを溝部の滞留効果とし、結果的に、このとき、燃焼音が解消されることが判明した。１３Ａガス等を用いる場合は、溝部の傾斜角度は２０度以上４５度以内とするのが好ましい。
従って、ＬＮＧに対応するには、溝部の傾斜角度を２０度以上４５度以内であることが望ましいから、前記凹溝３の側壁面の傾斜角度θは、前記小炎孔４の軸線に対して１０度〜４５度とする。
溝部の傾斜角度は２０度以上４５度以内とする燃焼プレートは、１３Ａ規格のガス用に適する。前記燃焼プレートは、１３Ａ規格のガス用かつ面負荷１７０ｋＷ／ｍ^２未満において使用するものである。
【００５３】
凹溝の深さＨは、前記実施例では１．５ｍｍ以上として説明したが、１３ＡとＢＰ３０ガスによる試験で、１．４ｍｍの深さの場合でも、実施例８に示したように使用できる範囲であることが判明した。図１６乃至図１８で、実施例７、８がその燃焼音の低下すること、燃焼量に対する表面温度が使用範囲であることを示す。従って、前記凹溝３は、深さが１．４ｍｍ以上とするのが好ましい。前記小炎孔４は、予混合気の予熱領域を確保しうる長さＬを備えている。この予混合気の予熱領域を確保しうる長さＬについては、前記実施例と同様にする。
【００５４】
以上のことから、ガス種に依ることなく低負荷域から高負荷域までの幅広い領域で燃焼量の制御が可能とするには、傾斜角度θを１０度以上４５度以内の範囲でＬＰＧ、ＬＮＧに対応するに適した傾斜角度θとする。
この発明によれば、ガス種に依ることなく低負荷域から高負荷域までの幅広い領域で燃焼量の制御が可能になる上に、燃焼音が解消される。また、燃料の節約およびＣＯ_２ 発生量の削減等にも繋がる。
この発明の赤外線バーナ２１は上記した構成の燃焼プレートを備え、燃焼効率を良くすることができる。
【００５５】
次に、この発明の燃焼プレートの実施例６〜８と従来例２の燃焼プレートとの低負荷領域における特性を比較する。この特性を比較するための試験方法は次のとおりである。
低負荷領域（面負荷；１３５〜１７０ｋＷ／ｍ^２ に対して１３ＡとＬＰＧを用いた双方の燃焼特性について説明する。特に燃焼音および表面温度特性に関する。
【００５６】

表面温度測定
燃焼開始後５分が経過した時点で左右各プレート表面中央付近の温度をそれぞれ測定し、その平均値を表面温度とした。表面温度の測定には、携帯用ディジタル放射温度計（大同特殊鋼製スターサーモＤＳ−０６ＣＦ）を用いた。輻射率を０．５０に設定。
【００５７】
なお、実験に使用した１３Ａガス（ＬＮＧ）と、ＢＰ３０ガス（ＬＰＧ）の性質と組成は次の通りである。
１３Ａガスの性質
総発熱量４６，０５５ｋＪ／ｍ^３
１３Ａガスの組成は一例を表５に示す。
【００５８】
【表５】

【００５９】
ＢＰ３０ガスの性質
総発熱量（２５℃、１ａｔｍ）： ４９７３５ｋＪ／ｋｇ
ＢＰガスの組成は一例を表６に示す。
【００６０】
【表６】

【００６１】
実験に使用した従来例２の燃焼プレートと、この発明の燃焼プレートの概要を説明する。
図１５に従来例２の燃焼プレートの一例の寸法を示す。従来の燃焼プレートは凹溝と突起自体に多数の炎孔が形成されている。

図１３に、この発明の燃焼プレートの一例の寸法を示す。

実施例６、７、８はその燃焼プレートの傾斜角度θと凹溝の深さＨを変えた場合である。

なお、この従来例２は前記従来例１と凹溝の深さ、傾斜角度はほぼ同じであるが、炎孔径は大きく異なる。また、実施例６と前記実施例３とでは、凹溝の深さ、傾斜角度、炎孔径、開孔率がいずれも同じ場合である。
【００６２】
表７にガス種と燃焼量の変化に対する着火後燃焼音が継続した時間の変化を示す。
【００６３】
【表７】

【００６４】
表７で、従来例２では、凹溝が浅く、凹溝の上部の錘型頂部の傾斜面の角度が６６度と開いているために１３Ａガス、ＢＰ３０ガス共に、燃焼音は発生しなかった。
実施例６では、１３Ａを用いた場合、面負荷１５５ｋＷ／ｍ^２ 以下の低燃焼では、燃焼音が顕著に発生し、燃焼開始以後１０分以上を経てもそれが鳴り止まなかった。一方、実施例６をＢＰ３０ガスで燃焼した場合には、面負荷１５３ｋＷ／ｍ^２ 以下のとき、燃焼音が発生し、着火後約４０秒経過したときにその燃焼音は消滅した。
【００６５】
以下に、凹溝の側壁面の傾斜角度θおよびガス種並びに燃焼量の違いによって変化する燃焼音につき考察する。
図１４（イ）、（ロ）、（ハ）は炎孔部下流域および溝部におけるガス噴出速度と火炎伝播速度とのつり合い状態を示す模式図で、図１４（イ）は実施例６で１３Ａガス１６５０Ｗの場合、図１４（ロ）は実施例７で１３Ａガス１６５０Ｗの場合、図１４（ハ）は実施例６でＢＰ３０ガス１６３０Ｗの場合における燃焼状態と噴出速度と燃焼速度とを示す。
図１４（イ）、（ロ）の場合、ａは赤熱、ｂは或る程度赤熱、ｃは殆ど赤熱されないこと、図１４（ハ）の場合、逆にｃが赤熱、ｂは或る程度赤熱、ａは殆ど赤熱されていないことを示す。図１４（イ）、（ロ）、（ハ）で上向きの矢印は噴出速度、下向きの矢印は燃焼速度を示す。
【００６６】
傾斜角度θの変化に対する燃焼音の有無に関する考察
１３Ａガスを用いて実施例６の燃焼プレートで燃焼量１６５０Ｗ（１５５ｋＷ／ｍ^２ ）で燃焼を行った場合には、図７（イ）に示すように、無炎孔とした突起部の先端ａのみが赤熱し、根元ｃは赤熱しなかった。
図１４（ロ）に示すように実施例７を同じ条件で燃焼した場合には、突起部先端から根元ｃまで赤熱した。
【００６７】
実施例６では、傾斜角度θが小さいことから、突起部根元ｃにおいてもガスの流速が速く、そのため、燃焼位置（火炎面）が下流側へ移行し、突起部根元ｃが赤熱しなかったと言える。よって、突起部根元では混合ガスが滞留し、それが燃焼音の発生に繋がったと考えられる。一方、実施例７および実施例８では、θが増大したことによって、燃焼速度とガス流速とのつり合いから、火炎面が突起部根元付近（上流側）にずれ、突起部根元ｃまで赤熱したといえる。突起部根元付近で燃焼が開始したことが、燃焼量を増大するに伴って燃焼開始後燃焼音が消滅するまでの時間が短くなることと符合する。
【００６８】
ガス種の変化と燃焼音の有無に関する考察
実施例６に対してＢＰ３０ガスを用いて燃焼量１６３０Ｗ（１５３ｋＷ／ｍ^２）で燃焼を行った場合には、突起部先端ａがやや暗く、突起部根元ｃが良好に赤熱した。ＢＰ３０ガスは１３Ａガスより燃焼速度が速いために（空気比λ＝１．０５における燃焼速度は、それぞれ１３Ａガス：約３３ｃｍ／ｓ、ＢＰ３０ガス：約３９ｃｍ／ｓ）、実施例６においても、火炎面が下流側へ移行することなく、突起部根元ｃが赤熱したと言える。また、後述するように、ＢＰ３０ガスを燃料にした場合には、燃焼負荷をさらに低下させた時にも顕著な燃焼音は発生しなかった。
従って、１３Ａガス等の燃焼速度の遅いガスを用いる場合には、傾斜角度θは、１５度より大きくする必要がある。
【００６９】
燃焼負荷と燃焼プレート表面温度の関係
表８に１３ＡガスおよびＢＰ３０ガスにおいて、燃焼量とプレート表面温度の関係を示す。
【００７０】
【表８】

【００７１】
図１６に１３Ａガスを用いた場合の低負荷域における燃焼量とプレート表面温度の関係を示す。図１７にＢＰ３０ガスを用いた場合の低負荷域における燃焼量とプレート表面温度の関係を示す。
【００７２】
１３Ａガスを用いた場合、１，８１２Ｗ（面負荷：１７０ｋＷ／ｍ^２ ）では、実施例６の傾斜角度θが小さい方（実施例６が傾斜角度が小さくて、実施例７、実施例８の順に傾斜角度は大きくなる）が表面温度がより高温に達したが、１，６５０Ｗ（面負荷：１５５ｋＷ／ｍ^２ ）以下の低負荷領域では、実施例６の表面温度は、実施例８程度にまで降下した（図１６）。このとき、むしろ、実施例７の表面温度は実施例６より高温であった。１３Ａガスによって１，６５０Ｗ（面負荷：１５５ｋＷ／ｍ^２ ）以下の低負荷燃焼をした場合、実施例６ではダイヤ部先端ａしか赤熱しなかった。これは、１３Ａガスの燃焼速度が小さいために火炎面が下流側に移行したことを示す。
【００７３】
次いで、ＢＰ３０ガスを用いた場合、１３５〜１６７ｋＷ／ｍ^２ の全域において、実施例６の傾斜角度θが小さい方（実施例６が傾斜角度が小さくて、実施例７、実施例８の順に傾斜角度は大きくなる）が表面温度がより高温であり、実施例６においても、１３Ａガスを低負荷燃焼した時に生じたような傾斜角θと到達表面温度との関係における逆転現象は生じなかった（図１７）。以上のことから、突起部傾斜角度θはガス燃焼速度（ガス種）と面負荷に応じて、燃焼音や表面温度に影響を及ぼすので、それらを勘案したθの最適化が必要となる。
【００７４】
図１６から、１３Ａガス燃焼では、実施例７を１５２ｋＷ／ｍ^２ 程度の低負荷で燃焼させたときの表面温度が、従来例２を１７０ｋＷ／ｍ^２ で燃焼させたときと同等程度であり、同様に、ＢＰ３０ガス燃焼でも、図１７から、実施例７を１４６ｋＷ／ｍ^２ で燃焼させたときの表面温度が従来例２を１６７ｋＷ／ｍ^２ で燃焼させたときと同等程度となることが判る。また、図１６および図１７を１６７ｋＷ／ｍ^２ との比較から、燃焼速度が速いＬＰＧ燃焼の時には、プレート表面温度がより高温になり易いと言える。これから、実施例７（θ＝２７度）は、従来例２（θ＝０度）対比、１０％以上の省エネルギー効果を奏するものと言え、とりわけ燃焼速度が速いＬＰＧ燃焼下では、実施例６（θ＝１５度）によれば、さらなる省エネルギー効果を見積もることができる。１３ＡとＬＰＧで、いずれの場合にも実施例８（θ＝４５度）に依るこの効果は十分とは言い難い。
【００７５】
本願プレート等による燃焼量制御性
図１８に種々のプレートを用いて燃焼量を変化させたときのプレート表面温度の変化を示した。
実施例６（θ＝１５度）ないし実施例７（θ＝２７度）によれば、幅広い領域で燃焼量の制御が可能になり、かつ、表面温度が従来のプレート（従来例２）より大幅に高温化する。図１８はＬＰＧを燃料とした時の結果であるが、１３Ａを燃料としたときにも、大略、同様の結果となる。
ただし、実施例６では、１３Ａを燃料とした場合に燃焼量が１，４００〜１６５０Ｗの範囲において燃焼音が顕著になり、表面温度も実施例７より降下する。従って、傾斜角度θが実施例６（１５度）より大きく、実施例８（４５度）より小さいプレートでは、用いる燃料の燃焼速度の違いに依らずとも本発明の効果が得られるので、ユニバーサル製品として使用できる（ガス種を選ばない）利点がある。
【００７６】
この発明によれば、例えば１３Ａ（都市ガス）等、燃焼速度の遅い燃料を用いて燃焼負荷を抑えて使用した場合においても燃焼音の発生を抑え、かつ実施例６に匹敵する範囲で燃焼量の制御ができる上に、従来例２と対比６〜１２％程度の低負荷においてもプレート表面温度が従来例２と同程度まで達する。
つまり、この発明によれば、ガス種に依ることなく低負荷域から高負荷域までの幅広い領域で燃焼量の制御が可能になる上に、燃焼音が解消される。また、燃料の節約およびＣＯ_２ 発生量の削減等にも繋がる。さらに、既設バーナとの置換によっても省エネルギーが容易に達成できる。
【００７７】
以上この発明の実施の形態の一例について説明したが、この発明はこうした実施の形態に何等限定されるものではなく、この発明の要旨を逸脱しない範囲において種々なる形態で実施し得ることは勿論である。上記した本実験では、最大燃焼量を４１８４Ｗ（そのときの表面温度は、実施例３および５において、約１１８０℃の最高温度に到達）とした。それは、実施例に用いたセラミックプレートの耐熱温度を勘案したものであり、さらに高耐熱性プレートを用いて本発明を実施すれば、より高い燃焼量領域にまで立ち入ることが可能であり、さらに高い表面温度（より大きなターンダウン比）が得られる。
【００７８】
【発明の効果】
この発明は、以上説明したような形態で実施され、以下に記載されるような効果を奏する。
【００７９】
この発明の燃焼プレートは、燃焼プレートの前記凹溝の幅方向の断面形状を燃焼時火炎により両側壁を赤熱可能な傾斜角度とし、火炎を滞留させる深さの台形状としたので、燃焼時に凹溝の下流方向への広がりで火炎を十分滞留させ、下流方向に開いた両側壁面の全面を赤熱することができ、燃焼効率を向上することができる。
上記燃焼プレートによれば、１個のバーナによって、ターンダウン比を３／１程度まで拡大することができ、表面温度が約８００度〜１１００度以上の範囲において調整ができる。
さらに、１１００度以上の高温表面を得るための面負荷が、約３１５〜２５０ｋＷ／ｍｍ^２ 程度にまで低減されるために、従来比、約４０〜５５％の燃料が節約でき、同時にＣＯ_２ 発生量を削減できる。
また、この燃焼プレートをバーナに使用すれば、高負荷燃焼時に際しても、立炎が解消されるので、燃焼プレート表面から被加熱物までの距離をこれまで以上に小さくすることができる。これに伴って加熱効率がさらに向上し、結果的に、装置のダウンサイジング（コンパクト化）や、処理時間の短縮化が実現されるなど、燃焼機器の省エネルギー性が増すとともに、燃焼量が可変となるので、設計自由度も拡大する。
【００８０】
この発明の燃焼プレートは、燃焼速度の速いＬＰＧ用プレートであって、かつ前記凹溝の側壁面の傾斜角度が小炎孔の軸線に対して１０度〜２０となっていることにより、その側壁全面を赤熱面として燃焼効率を最も良くすることができ、また、燃焼プレートは、燃焼速度の遅いＬＮＧ用かつ面負荷１７０ｋＷ／ｍ ^２ より低負荷燃焼での燃焼用プレートであって、かつ前記凹溝の側壁面の傾斜角度が小炎孔の軸線に対して２０度〜４５となっていることにより、側壁を赤熱して燃焼効率を上げることができ、また、前記凹溝の深さが１．４ｍｍ以上であることで、十分な火炎滞留効果をうることができて、凹溝の側壁面を赤熱させることができ、燃焼効率を上げることができる。
【００８２】
この発明の赤外線バーナは、前記した効果を有する燃焼プレートを備えるので、燃焼効率を良くすることができる。高負荷燃焼時に際しても、立炎が解消されるので、バーナ表面から被加熱物までの距離をこれまで以上に小さくすることができ、これに伴って加熱効率がさらに向上でき、また、燃焼量が可変できるので、使い勝手がよい。また、結果的に、装置のダウンサイジング（コンパクト化）や、処理時間の短縮化を実現できる。
【００８３】
この発明の燃焼プレートは、格子状に形成された凹溝と、該凹溝により側面が形成された多面体形状の多数の上方に延びる山形突起と、前記凹溝の底面に形成された多数の小炎孔とを備えた燃焼プレート、或いは多面体形状に形成された上方に延びる多数の山形突起と、該山形突起の側面を形成する凹溝と、該凹溝の底面に形成された多数の小炎孔とを備えた燃焼プレートに、火炎を滞留させるために幅が底面から上方に向かって広がるように凹溝が形成され、前記凹溝の側壁面の深さを１．４ｍｍ以上とすることで、十分な火炎滞留効果をうることができて、凹溝の側壁面を赤熱させることができ、燃焼効率を上げることができる。
【００８５】
この発明の燃焼プレートは、凹溝の側壁面の傾斜角度は、前記小炎孔の軸線に対して１０度〜２０度として、燃焼速度の速いＬＰＧに対応させ、また、この発明の燃焼プレートは、凹溝の側壁面の傾斜角度は、小炎孔の軸線に対して２０度〜４５度として、全面を赤熱面として燃焼効率を最も良くすることができ、燃焼速度の遅いＬＮＧ、例えば１３Ａに対応できる。また、前記凹溝の側壁面の深さを１．４ｍｍ以上とすることで、十分な火炎滞留効果をうることができて、凹溝の側壁面を赤熱させることができ、燃焼効率を上げることができる。
この発明によれば、ガス種に依ることなく低負荷域から高負荷域までの幅広い領域で燃焼量の制御が可能になる上に、燃焼音が解消される。また、燃料の節約およびＣＯ_２ 発生量の削減等にも繋がる。さらに、既設バーナとの置換によっても省エネルギーが容易に達成できる。
この発明の赤外線バーナは、前記した効果を有する燃焼プレートを備えるので、燃焼効率を良くすることができる。
【図面の簡単な説明】
【図１】図１はこの発明の燃焼プレートの一部拡大平面図である。
【図２】この発明の燃焼プレートの実施例１を示す断面図である。
【図３】同実施例２を示す断面図である。
【図４】同実施例３を示す断面図である。
【図５】従来例１の燃焼プレートを示す断面図である。
【図６】前記燃焼プレートを備えたこの発明の赤外線バーナを備えたガスバーナを示す断面図である。
【図７】この赤外線バーナをコンベアー上に多数配列した食品の焼成装置を示す説明図である。
【図８】燃焼プレート形状で得られる表面温度特性を示すグラフである。
【図９】プレート形状と保護金網の相乗効果を示すグラフである。
【図１０】炎孔長を７．５ｍｍとしたときの表面温度を示すグラフである。
【図１１】燃焼プレート上面からの深さと熱電対温度とを示すグラフである。
【図１２】燃焼プレートの実施例３を示す一部拡大平面図である。
【図１３】この実施例３の突起部の平面と側面の拡大図である。
【図１４】炎孔部下流域および溝部におけるガス噴出速度と火炎伝播速度とのつり合い状態を示す模式図で、（イ）は実施例６の１３Ａガスの場合、（ロ）は実施例７の１３Ａガスの場合、（ハ）は実施例６のＢＰ３０ガスの場合を示す。
【図１５】従来例２の突起部の平面と側面の拡大図である。
【図１６】１３Ａガスを用いた場合の低負荷域における燃焼量とプレート表面温度の関係を示すグラフである。
【図１７】ＢＰ３０ガスを用いた場合の低負荷域における燃焼量とプレート表面温度の関係を示すグラフである。
【図１８】ＬＰＧを用いた場合の燃焼量と表面温度の関係を示すグラフである。
【符号の説明】
１ 燃焼プレート
２ 山形突起
３ 凹溝
３ａ 側壁面
４ 小炎孔
２１ 赤外線バーナ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a combustion plate and an infrared burner used for an infrared burner designed to utilize infrared energy for heating, heat treatment, drying, cooking, and the like.
[0002]
[Prior art]
As a conventional combustion plate, a combustion plate of the applicant's patent No. 3015931, in which a large number of chevron convex portions are formed around a ceramic plate with a concave groove around it, and a flame hole is provided in the concave groove. However, in this conventional combustion plate, the cross-sectional shape of the groove in the width direction is rectangular with a side wall surface perpendicular to the axis of the flame hole and shallow in depth (usually 0.5 mm to 0.8 mm), and also in a mountain shape The top has a low height and a gentle slope.
[0003]
[Problems to be solved by the invention]
In the conventional combustion plate, the side wall surface of the groove 3 'is vertical and its depth is usually as shallow as 0.5 mm to 0.8 mm, and the cross-sectional shape in the width direction of the groove 3' is a rectangular shape with a shallow depth. The height of the chevron convex portion 2 'is low and the shape suddenly bends from the upper end of the concave groove to the upper surface of the convex portion (see FIG. 5). Although it becomes red hot, since the part close to the top of the protrusion is not directly heated, the central part of the protrusion becomes dark red and is not sufficiently red hot. From this knowledge, if the amount of combustion on the combustion plate is increased, the temperature rises as it is, but the surface temperature tends to saturate soon, and after that, it is observed as a standing flame or flashback. In practice, the amount of combustion cannot be increased. It also leads to energy loss.
Also, according to the prior art, some of the individual infrared burners have a surface temperature of 800 degrees to 1100 degrees or more. However, in this type of burner, since the possible turndown ratio for one burner is at most 1.5 / 1 (usually less than that), the turndown ratio cannot be obtained substantially. The surface temperature obtained was almost fixed. For example, the surface load for obtaining a surface temperature of about 800 degrees is about 157 kW / m.² On the other hand, in order to obtain a high temperature of 1100 ° C. or more, the surface load is about 550 kW / m.² It was necessary to raise it to the extent. As a means for such high-load combustion, means for reducing the flame hole area (decreasing the aperture ratio) in accordance with an increase in surface load is taken. Therefore, there has been no infrared burner that can achieve a wide range of temperature control from 800 degrees to 1100 degrees by one burner. In an infrared burner, a simple increase in the amount of combustion causes backfire and standing flame (adhered flame state), while the dark reduction of the amount of combustion causes a problem of defective combustion.
Easily increasing the amount of combustion to obtain a hot surface is not only from the viewpoint of saving fossil energy resources,₂ This is also not preferable from the viewpoint of reducing the amount released. In addition, since a standing flame is generated during high-load combustion, a loss occurs in the combustion energy for heating the combustion plate accompanying the standing flame, which also affects the efficiency of the infrared burner. There was a restriction when it was necessary to shorten the distance from the to the object to be heated.
On the other hand, in order to reduce the area of the flame holes, it is necessary to be sophisticated to accurately form the fine flame holes, or the complexity of the flame hole arrangement, which makes it difficult to manufacture the combustion plate. As a result, there were problems such as an increase in product cost.
[0004]
In order to solve the above problems, the inventors of the present invention have found that the cross section of the groove surrounding the vertical and horizontal protrusions of the combustion plate is trapezoidally open in the downstream direction to improve combustion efficiency and increase the turndown ratio. .
In view of this, the present invention forms a large number of flame-shaped projections in the surface of a combustion plate made of a refractory material in the vertical and horizontal directions with concave grooves around it, and a plurality of small flame holes are formed in the concave grooves. The combustion plate has been improved, and in particular the cross-sectional shape in the width direction of the concave groove can be red-heated by the flame, and the trapezoidal shape of the inclination angle and depth where the flame stays improves the combustion efficiency and expands the turndown ratio. An object of the present invention is to provide a combustion plate that can be adjusted in a range of a surface temperature of about 800 degrees to 1100 degrees or more. Moreover, it aims at providing the infrared burner provided with this combustion plate.
It is another object of the present invention to provide a combustion plate that expands the width of a concave groove from the bottom surface in order to retain a flame to improve combustion efficiency and expand a turndown ratio, and an infrared burner including the combustion plate. .
[0005]
[Means for Solving the Problems]
The combustion plate according to claim 1 of the present invention for solving the above-mentioned problem is provided with a groove 3 around the surface of the combustion plate 1 made of a refractory material. In a combustion plate formed vertically and horizontally with a plurality of small flame holes 4 having an opening ratio of 5% to 20% in the groove 3 as a whole, a recess provided around the chevron 2 The gist is that the cross-sectional shape in the width direction of the groove 3 is expanded in the downstream direction at an inclination angle θ at which both side walls 3a can be red-heated by a flame to form a trapezoid having a depth H for retaining the flame.
[0006]
  According to a second aspect of the present invention, there is provided a combustion plate according to the first aspect.The combustion plate is an LPG plate having a high combustion rate, andThe inclination angle of the side wall surface of the groove is 10 degrees to the axis of the small flame hole20 degreesThis is the summary.
  The combustion plate according to claim 3 is:2. The combustion plate according to claim 1, wherein the combustion plate is for LNG having a low combustion speed and a surface load of 170 kW / m. ² It is a combustion plate in a lower load region, and the gist is that the inclination angle of the side wall surface of the groove is 20 to 45 degrees with respect to the axis of the small flame hole.
Claims of the invention4The combustion plate according to claim 1.Or in any of 3GrooveThe depth H is 1.4It is gist that it is more than mmThe
[0007]
  An infrared burner according to claim 5 of the present invention for solving the above-mentioned problems is provided.The combustion plate according to claim 1 is provided.This is the gist.
[0008]
  A combustion plate according to a sixth aspect of the present invention includes a concave groove 3 formed in a lattice shape, a large number of polyhedrally shaped protrusions 2 having side surfaces formed by the concave groove 3 and extending upward, and the concave grooves It is a combustion plate 1 made of a refractory material having a large number of small flame holes 4 formed on the bottom surface, and the concave groove 3 is formed so that the width widens upward from the bottom surface in order to retain the flame. TheAnd the depth is 1.4 mm or moreIt is characterized by this.
[0009]
  The combustion plate according to claim 7 of the present invention is formed in a large number of upwardly projecting chevron protrusions 2 formed in a polyhedral shape, a concave groove 3 forming a side surface of the chevron protrusion, and a bottom surface of the concave groove. It is a combustion plate 1 made of a refractory material having a large number of small flame holes 4, wherein the concave groove 3 is formed so that its width widens upward from the bottom surface in order to retain the flame.And the depth is 1.4 mm or moreIt is characterized by this.
[0014]
The combustion plate according to claim 1 of the present invention having the above-described structure is a depth in which the cross-sectional shape in the width direction of the concave groove of the combustion plate is expanded in the downstream direction at an inclination angle at which both side walls can be red-heated by the flame, and the flame is retained. Because of the trapezoidal shape, the flame is sufficiently retained in the groove during combustion, and the entire surfaces of both side walls opened in the downstream direction by the flame can be red-heated, and the combustion efficiency can be improved.
[0015]
  The combustion plate according to claim 2 of the present invention having the above-described configuration is as follows.An LPG plate with a fast burning rate, andThe inclination angle of the side wall surface of the groove is 10 degrees to the axis of the small flame hole20By setting the degree within the range, the entire side wall surface of the groove can be made a bright red surface to improve the combustion efficiency.
The combustion plate according to claim 3 of the present invention having the above-described configuration is for LNG having a low combustion rate and a surface load of 170 kW / m. ² It is a combustion plate for lower load combustion, and the inclination angle of the side wall surface of the groove is in the range of 20 degrees to 45 degrees with respect to the axis of the small flame hole, so that the side wall of the groove Can be red-hot, and combustion efficiency can be improved.
[0016]
  Claims of the present invention having the above-described configuration4The listed combustion plate isSaidGroove depth1.4Since it is possible to obtain a flame retention effect by being at least mm, combustion efficiency can be improved.The
[0017]
Since the infrared burner according to claim 5 of the present invention having the above-described configuration includes the combustion plate having the above-described effects, an infrared burner with improved combustion efficiency can be provided.
[0018]
  The combustion plate according to claim 6 of the present invention having the above-described configuration is a concave groove formed in a lattice shape, a large number of polyhedrally-shaped protrusions having side surfaces formed by the concave groove, and the concave groove In order to retain the flame in the combustion plate having a large number of small flame holes formed on the bottom surface of the, a groove is formed so that the width widens upward from the bottom surface. A dwell groove formed so as to sufficiently stay in the flame and spread upward from the bottom surface with the flame can be red-hot, and the combustion efficiency can be improved.By making the depth of the concave groove 1.4 mm or more, a flame retention effect can be obtained, so that the combustion efficiency can be improved.
[0019]
  A combustion plate according to claim 7 of the present invention having the above-described configuration is formed on a plurality of upwardly extending chevron projections formed in a polyhedron shape, a concave groove forming a side surface of the chevron projection, and a bottom surface of the concave groove. In order to retain the flame in the combustion plate having a large number of small flame holes, the groove is formed so that the width widens upward from the bottom surface, so that the flame is sufficiently retained in the groove during combustion. The groove formed so as to spread upward from the bottom surface by the flame can be red-hot, and the combustion efficiency can be improved.By making the depth of the concave groove 1.4 mm or more, a flame retention effect can be obtained, so that the combustion efficiency can be improved.
[0021]
  This invention having the above configurationBurningIn the baking plate, the inclination angle of the side wall surface of the concave groove is set to 10 degrees to 20 degrees with respect to the axis of the small flame hole to correspond to LPG having a high combustion rate. Also,Of this inventionFor the combustion plate, the inclination angle of the side wall surface of the groove is relative to the axis of the small flame hole.20Degree to 45 degreesBurningIt can cope with LNG with a slow baking rate, for example, 13A.
  This inventionBurningThe baked plate is for 13A standard gas.13A standard gas and surface load 170kW / m²It is used in less than.
[0022]
  This invention having the above configurationBurningSince the baking plate can obtain the flame retention effect by setting the depth of the concave groove to 1.4 mm or more, the combustion efficiency can be improved. This inventionBurningThe firing plate has a flame hole length of the combustion plate that is long enough to ensure a preheating region of the premixed gas, thereby further improving the combustion efficiency by the synergistic effect of the depth of the groove and the inclination angle. it can.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
In order to further clarify the configuration and operation of the present invention described above, embodiments of the combustion plate of the present invention will be described in detail with reference to the drawings.
1 is a partially enlarged plan view of a combustion plate of the present invention, FIG. 2 is a cross-sectional view showing a first embodiment of the combustion plate of the present invention, FIG. 3 is a cross-sectional view showing the second embodiment, and FIG. FIG. 5 is a cross-sectional view showing a combustion plate of Conventional Example 1. As shown in FIG.
[0026]
FIG. 1 shows an embodiment of a combustion plate according to the present invention. Reference numeral 1 is a rectangular combustion plate made of a refractory material having a high fire resistance such as cordierite and mullite refractory, and a large number of rhombuses ( A diamond-shaped projection 2 having a flame-free hole is formed in a vertical and horizontal shape with a narrow groove 3 around it, and a number of small flame holes 4 are drilled in the groove 3 at regular intervals. Set up. The small flame hole 4 has a diameter that increases the gas ejection speed so that the combustion position is in the vicinity of the downstream end of the flame hole, and keeps the balance between the increase of the gas ejection speed and the flame propagation speed for combustion. preferable.
As the combustion gas, for example, LNG (liquefied natural gas) such as 13A gas, 12A, LPG (liquefied petroleum gas) such as propane gas, butane gas or the like is used.
The rhombus-shaped protrusion 2 of this embodiment is formed in a quadrangular pyramid shape with the center at the top, and twelve small flame holes 4 are formed in the groove 3 surrounding it, and the groove 3 has a diameter of 0.7 mmφ to 0 mm. .A large number of small flame holes 4 with a diameter of 95 mm are drilled through the front and back, and the overall plate opening rate (flame hole total area / plate area) is about 5% to 20%, and the gas ejection speed is increased. Thus, the combustion position can be extended to the vicinity of the downstream end of the flame hole and burned while maintaining the balance between the increase in gas ejection speed and the flame propagation speed, thereby preventing backfire due to gas ejection.
In the embodiment, the bottom surface of the protrusion 2 is a rhombus (diamond shape), but is not limited to this shape, and may be a polygonal shape such as a square shape or a circular shape. Further, the size of the small flame hole is not limited to the above-mentioned size, and may be a conventional diameter of about 1 mm.
Although the said embodiment showed the case where a flame hole was provided also in the site | part which the vertical and horizontal ditch | groove of the combustion plate 1 crossed, it is not restricted to this, For example, the flame hole of the site | part where a ditch | groove intersects is shown. A flameless hole portion may be provided in the four sides of the rhomboid protrusion 2 by closing (as a blind) so as to reduce the hole area ratio and enable higher-load combustion. This combustion plate has almost the same action as the above combustion plate, and the opening ratio can be reduced by the amount of blockage of the intersection of the grooves, so the gas injection speed is increased accordingly, the gas injection speed is increased, and the flame propagation It is possible to burn while maintaining the balance with the speed, and to prevent the flashback phenomenon due to gas ejection.
[0027]
In the combustion plate 1 of the present invention, in the above-described combustion plate, the cross-sectional shape in the width direction of the groove 3 provided around the chevron 2 can be red-heated by a gas flame with both side walls 3a as small flow holes. It is characterized by being formed in a trapezoidal shape having a depth H that spreads in a downstream direction at a small inclination angle θ and retains the flame. In this way, the concave groove of the combustion plate has a trapezoidal shape and has a depth and depth in the downstream direction, so that the gas and flame ejected from the small flame hole in this concave groove are decelerated and sufficiently retained, and the concave groove The entire surfaces of the inclined side wall surfaces are red-heated to improve the combustion efficiency.
[0028]
1 to 4 show a case where the cross-sectional shape in the width direction of the concave groove surrounding the projection of the combustion plate of the present invention is changed, and FIG. 5 shows the cross-sectional shape of the combustion plate of Conventional Example 1. In FIG.
The cross-sectional shape in the width direction of the concave groove 3 of the combustion plate 1 is a trapezoidal shape in which both side walls 3a are expanded downstream at an inclination angle θ that can be red-heated by a flame and the depth is H for retaining the flame.
The inclineable inclination angle θ of both side wall surfaces 3 a of the concave groove 3 of the combustion plate 1 is an angle formed by the both side wall surfaces 3 a with respect to the axis of the small flame hole 4. The inclination angle θ is preferably 10 degrees to 20 degrees or less. In the case of LPG having a high combustion rate, the inclination angle θ is more preferably 10 degrees to 15 degrees. By giving the above-mentioned inclination angle to the side wall surface 3a of the groove, the gas ejection speed or the flame speed from the small flame hole is decelerated by spreading to the downstream of the groove and the groove side wall is red hot while staying in the groove, The combustion reaction is promoted along with the red heat, so it is considered that a large turndown is possible while suppressing the standing flame even at high load. When assuming an LPG with a high combustion rate, it is not preferable to open the inclination angle θ by 20 degrees or more because the effect of flame retention is reduced.
The width of the bottom of the concave groove 3 having a trapezoidal cross section is formed to be substantially the same as or slightly wider than the diameter of the small flame hole 4, and a small flame hole is provided at the center. In the figure, the width of the bottom of the concave groove and the diameter of the small flame hole are the same.
Moreover, as the depth H at which the flame is retained in order to red heat the side wall 3a of the groove 3 of the combustion plate 1, at least the depth of the groove from the upper surface of the flame hole is 1.5 mm or more. The reason why the depth is set to 1.5 mm is that the conventional 0.5 to 0.8 mm is red hot by the flame, but the red hot surface is too narrow, and when the flame is in the standing flame state or exfoliation flame state, the gas is blown out. The narrow groove is cooled, and the side wall surface of the narrow groove is not sufficiently red-hot. As a result of the test, the red-hot surface is narrow at 1.5 mm or less, and a sufficient flame retention effect is obtained. It was found that it was not obtained. By increasing the depth by at least 1 mm from the current level, the surface temperature increased and the occurrence of flame was also suppressed. As a result of investigating the combustion characteristics for the depth of the groove in the plate, it was found that the deeper the groove, the higher the surface temperature of the plate and the less the occurrence of flame. If the small flame hole has a small diameter as in the embodiment, the gas and flame speed are increased, and the combustion position can be moved to the downstream side accordingly, so that the combustion can be effectively performed by setting the depth to the above-mentioned depth. . At the same time, the flashback phenomenon can be prevented. The combustion noise was equivalent to the conventional high temperature plate. Therefore, the depth H of the concave groove 3 needs to be at least 1.5 mm or more. The upper limit of the depth of the concave groove 3 is set to a range in which the side wall surface 3a can be red-hot with a flame. The upper limit of the groove is determined by the size and shape of the protrusion. In Examples 1, 2, and 3, the test was performed by changing the height of the groove, the height of the top of the chevron, and the height of the flame hole length. The width of the protrusions of Examples 1 to 3 is 3.02 mm, and the diameter of the small flame hole 4 is 0.85 mmφ. In the case of Example 3, when the inclination angle is 15 degrees, the protrusion has a triangular cross section. In the manufacture of the combustion plate, the height of the protrusion (diamond) is set until the diamond rises. Actually, in the case of the third embodiment, it is necessary to make the top portion close to the upper end in the same manner as in the second embodiment, in the form of a mountain, to be flat, or to be rounded.
The combustion plate 1 is preferably made of a material having a high porosity, and the use of this material can further improve the combustion efficiency. If a material with high porosity is used as the plate material, the groove is deepened, and the side wall surface is inclined, high-temperature surface combustion is possible in which backfire is unlikely to occur.
Further, the flame hole length L of the flame hole 4 of the combustion plate 1 is set to a length that can secure a preheating region of the premixed gas as will be described later.
The combustion plate according to the present invention burns with a small flame hole in the groove to increase the gas ejection speed, and the cross-sectional shape in the width direction of the groove has an inclination angle at which both side walls can be red-heated by the flame, so that the flame is retained. Since the trapezoidal shape has a depth that allows the flame to stay in the downstream direction of the groove during combustion, the entire surface of both side walls opened in the downstream direction can be red-hot, improving combustion efficiency. it can. It is possible to prevent the occurrence of a flashback phenomenon. That is, according to the present invention, it is possible to improve the combustion efficiency regardless of the conventional flame hole diameter combustion plate or the degree of opening rate. Moreover, restrictions on the accuracy of formation of the flame holes, such as the opening ratio of the flame holes in the recessed grooves or the flame hole diameter, can be reduced, and the manufacture of the combustion plate can be facilitated. As a result, an inexpensive product can be provided.
[0029]
  The width B of the groove 3 of the combustion plate of Example 1 shown in FIG. 2 is 0.85 mm at the lower end, the inclination angle θ of the side wall surface 3a is 15 degrees, the depth H of the groove is 1.8 mm, When the height H1 is 0.5 mm and the flame hole length L is 11.5 mm,
  The width B of the concave groove 3 of the combustion plate of the second embodiment shown in FIG. 3 is such that the lower end is 0.85 mm and the side wall surface 3a is inclined at an inclination angle θ of 15 degrees.GroovedDepth H is 4.1 mm,Height H of Yamagata 1Is 0.2 mm and the flame hole length L is 9.5 mm,
  The width B of the groove 3 of the combustion plate of the third embodiment shown in FIG. 4 is 0.85 mm at the lower end, the inclination angle θ of the side wall surface 3a is 15 degrees, the depth H is 5.3 mm, and the flame hole length L is 8. The case where it is set to 5 mm is shown.
  In any of the examples, the diameter of the flame hole is 0.85 mm which is the same as the width B of the lower end of the groove.
  The combustion plate of Conventional Example 1 shown in FIG. 5 has a concave groove width B of 0.85 mm, a side wall surface is vertical, a depth of 0.5 mm, a chevron height H1 of 0.8 mm, and a flame hole length L. Is 12.5 mm.
[0030]
The characteristics of Examples 1 to 3 of the present invention and Conventional Example 1 are compared. The test method for comparing these characteristics is as follows.
[0031]

Combustion plate surface temperature measurement
When 5 minutes passed after the start of combustion, the temperatures near the center of the left and right plate surfaces were measured, and the average value was defined as the surface temperature.
For the measurement of the surface temperature, a portable digital radiation thermometer (Daido Special Steel Star Thermo DS-06CF) was used. Set the emissivity to 0.50.
[0032]
Under the above conditions, in the case of Conventional Example 1 and Examples 1 to 3 of the present invention, the surface temperature when the combustion amount W was set to 1647, 2510, 3347, 4184 was measured. The results shown in FIG. 10, Table 1, Table 2, and Table 3 were obtained. First, FIG. 8 is a graph showing the relationship between the combustion amount W and the surface temperature ° C. with respect to the surface temperature characteristics obtained with the combustion plate shapes of the conventional example 1 and the embodiment of the present invention. Surface temperature characteristics and surface load (kW / m) obtained with the combustion plate shape of each example corresponding to W)²) Is shown. Note that 1674W is a standard input in this experimental burner.
Total combustion (standard input); W
Surface load = W / plate area; W / mm²
Flame hole load = W / total area of flame hole; W / mm²
When standard input is 1474W
Surface load = 157 kW / m²
Flame hole load = 841 kW / m²
With a burner plate with an open area ratio of more than 20% (for example, small flame holes are also formed in the chevron projections and the small flame holes are 1.0 mmφ and 1.2 mmφ), the flame hole load is 841 kW / m²It is much smaller (1/2 or less), so the surface load is 157 kW / m² If it exceeds, a flashback will occur quickly. In addition, it is difficult to form a hole area ratio of 5% or less. Therefore, according to the present invention, the aperture ratio of the small flame holes as a whole is set to 5% to 20% so as not to cause this flashback phenomenon. In the experiment, as described above, the hole area ratio is 18.7%.
[0033]
[Table 1]

[0034]
8 and Table 1, the characteristics of Conventional Example 1 and the combustion plates of Examples 1 to 3 of the present invention are compared.
In Conventional Example 1, even if the combustion amount is increased to 4184 W, the surface temperature of the combustion plate only rises to about 1013 ° C. That is, with the conventional combustion plate, even if the combustion amount is increased by 2 to 2.5 times, it is difficult to increase the surface temperature following the increase.
In Examples 1 to 3 of the present invention, the surface temperature increased as the combustion amount (surface load) increased. Further, the surface temperature at the same combustion amount gradually increased in the order of Example 1 to Example 3.
8 and Table 1, in Conventional Example 1, 315 kW / m² With a surface load of (combustion amount 3347W) or more, the increase in surface temperature accompanying the increase in surface load was mitigated. Moreover, surface load 393kW / m²The surface temperature exceeded 1000 ° C. (combustion amount 4184 W).
In contrast, in Examples 1 to 3 of the present invention, the surface load is 393 kW / m.²In (combustion amount 4184W), the temperature reached around 1100 ° C. or much higher. Based on the experimental results of Example 3, about 253 kW / m²  It can be understood that the temperature has already reached 1100 ° C. at a relatively low surface load (combustion amount: about 2700 W). In Example 3, the combustion temperature was 4184 W and the surface temperature reached 1173 ° C. The burning surface was very bright and the entire diamond was red hot. Further, even when the combustion amount (input) is increased by increasing the depth of the diamond groove, there is no flame, and the plate of Example 3 burns about 2.5 times the standard input. There was no occurrence of flames. In any diamond shape, the combustion amount was equivalent to the combustion noise of a normal high temperature plate.
[0035]
In comparison between Conventional Example 1 and Example 1 of the present invention, the surface load is 157 kW / m.²There was no particular difference in the surface temperature at a low load (combustion amount 1673 W) or less, but a difference occurred at a higher load than that.
In order to consider the reason for this result, it is necessary to pay attention to the volume and shape of each groove.
In Conventional Example 1, the cross-sectional shape of the groove is short and rectangular, the space volume formed into a rectangular shape by the groove is small, the red hot area is small, and the flame does not stay in the groove and the flame is formed downstream of the groove. As shown in Table 1 and FIG. 8, the rise in the surface temperature of the plate is gradual and low even when the surface load is increased, up to a surface temperature slightly exceeding 1000 degrees.
On the other hand, the trapezoidal groove 3 of the present invention has a space for completing the combustion by forming a flame and staying of combustion gas, or mixing a small amount of unburned components with secondary air ( Acts as a firebag). Moreover, since the groove part side wall surface 3a is directly exposed to a combustion flame, it serves as a substantial red hot part.
In Examples 1 to 3, since the groove portion is deep and trapezoidal, a synergistic effect due to an increase in the groove side wall area and groove space volume, and the like, flame formation and combustion gas retention, or slight unburned components are Combustion can be completed by mixing with the secondary air.
In Example 1, the effect of the present invention is exhibited after the surface load increases to some extent. That is, as described above, the surface load is 157 kW / m.² However, although it is not much different from Conventional Example 1, the surface load is 236 kW / m.²As a result, the surface temperature already exceeded 1000 ° C., and the surface load increased, so that it could be increased to nearly 1100 ° C. In Examples 2 and 3, the effect of the present invention was already exhibited in the low load range. That is, the surface load 157 kW / m²  Surface temperature is high, surface load 236kW / m²Thus, the surface temperature exceeded 1000 ° C., and the surface temperature could be increased to 1133 ° C. in Example 2 and 1173 ° C. in Example 3 by increasing the surface load.
[0036]
In the combustion plates of Conventional Example 1 and Example 1, the surface load is 393 kW / m.² The state of the combustion flame at the time of high load combustion (combustion amount 4184W) was observed from the side.
In Conventional Example 1, it was confirmed that a bright flame was formed above the concave groove 3 ′ of the combustion plate and the standing flame extended upward. That is, since the groove of the conventional combustion plate is shallow, there is no sparking effect, there is little red hot surface, a flame is formed above (downstream) the groove 3 ', and a standing flame is generated.
On the other hand, in Example 1 of the present invention, the flame stayed in the concave groove 3 and the side wall surface was red-hot, high-temperature surface combustion could be realized by suppressing the flame, and almost no standing flame was seen. It will be understood that the groove according to the present invention provides a suitable sparking effect. That is, the side wall surfaces inclined on both sides are red-heated due to the flame effect in the groove, and the whole is red-hot, so that the low energy flame is suppressed not only on the side wall surface but also on the entire surface including the top of the protrusion. It is formed.
[0037]
Next, the case where the protective wire mesh is not provided in Examples 1 and 3 is compared with the case where the protective wire mesh is provided.
The surface temperature characteristics obtained when using the combustion plate of Example 1 (without a wire mesh) and Example 3 (without a wire mesh) and when a protective wire mesh is disposed thereon are shown in Example 4 (with a wire mesh) and Example 5 ( With wire mesh). The protective wire mesh used in Examples 4 and 5 is installed on the upper surface of the plate of the above example with an interval as in the example of FIG. This wire mesh has the effect of preventing damage to the combustion plate even when subjected to significant external stresses such as falling objects or impact force on the surface of the combustion plate. In addition, by installing this wire mesh, flame retention It is known from experience that the flame is suppressed due to the effect of the material, and that the surface temperature of the combustion plate further rises as a result of, for example, better mixing of the secondary air.
FIG. 9 is a graph showing the relationship between the combustion amount W and the surface temperature ° C. with respect to the synergistic effect of the plate shape and the protective wire mesh, and Table 2 corresponds to the combustion amount W (W) for the surface temperature obtained with the protective wire mesh. The surface temperature characteristics obtained with the shape of the combustion plate of each example are shown.
[0038]
[Table 2]

[0039]
In the results of FIG. 9 and Table 2, the characteristics of the combustion plates of Examples 1, 3, 4, and 5 of the present invention are compared.
The above-described combustion promotion effect produced by the action of the concave groove is apparent from FIG. 9 (results of installation of the wire mesh in Example 4 and Example 5).
In Example 4 and Example 5, the surface temperature characteristics when a protective wire mesh was installed above the combustion plate were examined. The combustion plate is the same as that of Example 1 and Example 3 used in this experiment.
[0040]
In FIG. 9 and Table 2, this is shown by the difference in surface temperature characteristics between Example 1 (without wire mesh) and Example 4 (with wire mesh). That is, by placing a wire mesh, the surface temperature was higher than when there was no wire mesh, and the surface temperature was 1105 ° C. with a combustion amount of 3347 W. By placing a wire mesh, the occurrence of flame was also suppressed. Therefore, the diamond shape showing the most excellent combustion characteristics is the case of Example 3 in which the depth of the groove is maximum, and Example 5 in which a protective wire mesh is arranged. Most preferably, the combustion plate is made in this diamond shape.
On the other hand, in Example 5 (with a wire mesh), the difference from Example 3 (without a wire mesh) hardly occurred. From this, it is understood that the combustion plate of Example 4 has a combustion promotion effect comparable to the action of the wire mesh known from experience as described above. Therefore, according to the present invention, it is possible to reduce the number of parts associated with the wire mesh and its arrangement.
[0041]
FIG. 10 shows the relationship between the combustion amount W and the surface temperature ° C. for the surface temperature characteristics when the flame hole length is 7.5 mm, and Table 3 shows examples corresponding to the combustion amount W (W). The surface temperature characteristics obtained with the shape of the combustion plate are shown.
[0042]
[Table 3]

[0043]
It is the result of examining the surface temperature characteristics when the groove shape of the combustion plate is the same as in Example 1 and the flame hole length L is 7.5 mm, which is shorter than that in the above example. Comparative Example 1 shows surface temperature characteristics when the flame hole length of Example 1 is 7.5 mm.
In Table 3, in the case of Comparative Example 1, the surface temperature rise accompanying the increase in the amount of combustion did not reach Example 1. Even if the concave groove is the same as in Example 1, if the flame hole length is shortened, the surface temperature becomes low and becomes almost similar to the surface temperature characteristic of Conventional Example 1, so if the flame hole length is too short, It turned out to be ineffective. Therefore, when designing an infrared burner that enables a significant turndown, it is necessary to determine the flame hole length to such an extent that a preheating region of the premixed gas is secured.
In order to consider the reason, a plurality of thermocouples were embedded in the combustion plate of Example 1 and the temperature distribution inside the plate was measured. The results are shown in FIG.
[0044]
[Table 4]

[0045]
In FIG. 11 and Table 4, the temperature hardly increased from the most upstream of the flame hole (depth 12.0 mm) to near the depth of 6 mm, and the temperature rapidly increased downstream from the depth 6 mm (plate surface side). Later, since the temperature becomes constant at a point slightly downstream (near the surface) from a depth of 1.5 mm, it is considered that the flame surface exists in this vicinity. This can be said to be the in-plate combustion characteristic of infrared burners.
In the steady state where there is no heat transfer due to convection, the heat transfer in the flow direction of the premixed gas in the plate is only due to heat conduction, and the temperature gradient should be constant as in the heat conduction in a homogeneous flat plate. is there. However, the temperature gradient is not constant in the results of this experiment. This is considered to be due to the heat transfer to the premixed gas. Combustibility is improved by preheating the premixed gas.
As for the heat transfer in the plate upstream (on the premixed gas inlet side) from the flame surface, if radiation is ignored, it may be considered that there is no heat transfer in the upstream direction other than heat conduction by ceramics. Since there is already a room temperature in the plate on the upstream side of the flame hole, it is considered that the amount of heat transmitted in the upstream direction was all used for preheating the premixed gas.
When the surface load is further increased, the flow velocity of the premixed gas flowing in the flame hole increases, and at the same time, the flame surface moves further downstream. If the surface load continues to increase, it will eventually shift from the in-plate combustion state to the attached flame state (standing flame state), and further to the peeling flame state (blue frame state).
Therefore, when designing an infrared burner that enables significant turndown, the flame hole length should be determined to the extent that the preheated area of the premixed gas is secured, and the flame surface reaches the most downstream area with high load combustion. Even if it moves, it is necessary to provide a fire bag structure that can still contribute to the red heat of the plate surface.
[0046]
From the above experiment, according to the combustion plate of the present invention, the turndown ratio can be expanded to about 3/1 by one burner, and the surface temperature can be adjusted in the range of about 800 degrees to 1100 degrees or more. .
Furthermore, the surface load for obtaining a high temperature surface of 1100 degrees or more is about 315 to 250 kW / mm.²  As a result, the fuel can be saved by about 40 to 55% compared with the conventional case, and at the same time, CO can be saved.₂  The amount generated can be reduced.
Even during high-load combustion, since the standing flame is eliminated, the distance from the surface of the combustion plate to the object to be heated can be made smaller than before. Along with this, the heating efficiency is further improved, and as a result, downsizing (compacting) of the device and shortening of the processing time are realized. As a result, the degree of freedom in design is expanded.
[0047]
FIG. 6 is a sectional view showing a gas burner provided with the infrared burner of the present invention provided with the combustion plate, and FIG. 7 is an explanatory view showing a baking apparatus provided with a plurality of the infrared burners.
[0048]
In the gas burner shown in FIG. 6, the one or more combustion plates 1 are provided on the upper surface of the burner body 10 with ceramic wool 11 interposed therebetween, and a protective wire mesh 12 is provided on the upper surface of the combustion plate 1 with an interval. ing. In the figure, reference numeral 13 is a mixed gas ejection nozzle, 14 is a throat, 15 is a mixed gas passage, 16 is a baffle plate, and 17 is a combustion plate support. The combustion plate of the burner is ignited with an ignition rod or the like, or ignited with an ignition device such as a spark plug and a pilot burner.
According to the infrared burner provided with the combustion plate of the present invention, the standing flame is eliminated during high-load combustion, so that the heating efficiency of the object to be heated can be further improved, downsizing (compacting) of the apparatus and shortening of the processing time. Can be realized.
In addition, although the case where the protection wire mesh was provided was shown in the said Example, it is not restricted to this, It is not necessary to provide a protection wire mesh.
[0049]
In FIG. 7, a baking apparatus for food and the like is shown. In this baking apparatus, a plurality of infrared burners 21 of the present invention are installed in parallel on the belt conveyor 26 at an arbitrary interval, and the food placed on the belt conveyor 26 is baked while moving. In the figure, reference numeral 22 is a fuel passage, 23 is a blower, 24 is a mixer, 25 is a hot air duct, 26 is a conveyor, P1 to P5 are pressure gauges, V1 to V5 are valves, and G1 to G2 are governors.
Conventionally, it was necessary to examine the installation position (burner interval, height), etc. of the burner so as to obtain a temperature gradient suitable for heat treatment, but according to the present invention, the surface temperature can be controlled over a wide range. A temperature rise curve suitable for processing is easily set by adjusting the amount of combustion. In addition, since the standing flame is eliminated during high-load combustion, the distance from the burner surface to the object to be heated can be made smaller than before, and the heating efficiency of the object to be heated on the belt conveyor is further improved accordingly. it can.
The combustion plate of the present invention is effective when used in a burner that forcibly feeds air using a blower.
[0050]
12 is a partially enlarged plan view showing a third embodiment of the combustion plate, FIG. 13 is an enlarged view of a plane and a side surface of the projection portion of the third embodiment, and FIG. 14 is a gas ejection speed and flame in the downstream area and groove portion of the flame hole. FIG. 5 is a schematic diagram showing a balanced state with the propagation velocity, where (A) is the case of 13A gas of Example 6, (B) is the case of 13A gas of Example 7, and (C) is the case of BP30 gas of Example 6. FIG. 15 is an enlarged view of the flat surface and the side surface of the protrusion of the second conventional example.
[0051]
1, 12, and 13, reference numeral 1 denotes a combustion plate made of a refractory material, and includes a plurality of concave grooves 3 formed in an oblique lattice shape and a polyhedral shape having side surfaces formed by the concave grooves 3. A chevron 2 extending upward and a plurality of small flame holes 4 formed on the bottom surface of the groove 3 are provided. The combustion plate 1 includes a large number of chevron protrusions 2 formed in a polyhedral shape and extending upward, a concave groove 3 that forms a side surface of the chevron protrusion 2, and a large number of small flame holes formed in the bottom surface of the concave groove 3. 4 is provided.
And the said groove 3 is formed so that a width may spread upwards from a bottom face in order to make a flame stay. The concave groove 3 has a substantially uniform width at the bottom surface in the entire concave groove, and a substantially uniform width at the upper end in the entire concave groove. The concave groove 3 is formed so that its width widens upward from the bottom surface in order to retain the flame, and its side wall surface is formed at an inclination angle θ with respect to the axis of the small flame hole.
A large number of chevron projections 2 of the combustion plate of the embodiment are arranged in a tetrahedron shape (diamonds) vertically and horizontally, and a concave groove 3 having the shape is formed between the chevron projections 2. The width B of the bottom surface of the groove 3 is the same as or slightly wider than the small flame hole 4. A plurality of small flame holes 4 having a diameter of 0.7 mmφ to 0.95 mmφ are formed in the intersection portion of the chevron projection 2 and the groove 3 at substantially equal intervals. In the embodiment, two on each side of the groove 3 of each chevron protrusion 2 and one on the intersection are provided at equal intervals.
The number of small flame holes 4 drilled in the concave groove 3 with respect to the combustion plate is 5% to 20% as described above, and the gas ejection speed is increased to set the combustion position at the downstream end of the flame hole. It can be extended to the vicinity and burned while maintaining a balance between the increase in gas ejection speed and the flame propagation speed, thereby preventing backfire due to gas ejection.
[0052]
The side wall surface of the groove 3 is an inclined surface. In the above-described embodiment, the inclination angle θ of the side wall surface of the groove is 10 degrees to 20 degrees with respect to the axis of the small flame hole. Degree.
When assuming an LPG with a high combustion rate, opening the inclination angle θ of 20 degrees or more is not preferable because the flame retention effect is reduced, but the following test has revealed the following.
That is, for example, when the plate of Example 6 is used in a state where the combustion amount is suppressed (low-load combustion) using a fuel with a slow combustion speed such as LNG 13A gas, 12A gas, etc., the combustion noise does not stop. There is a problem.
Thus, under the 13A gas and 12A gas, which have a slow combustion rate, the combustion flame tends to shift to the downstream side rather than the LPG. Therefore, particularly in the case of low load combustion, the inclination angle of the groove is further relaxed. By opening (opening 20 degrees or more), the speed at which the mixed gas is ejected from the narrow flame hole (flow velocity of the combustion gas) is further reduced, and the flame surface can be maintained upstream (near the flame hole). . This was regarded as the retention effect of the groove, and as a result, it was found that the combustion noise was eliminated at this time. When 13A gas or the like is used, the inclination angle of the groove is preferably 20 degrees or more and 45 degrees or less.
Therefore, in order to cope with LNG, it is desirable that the inclination angle of the groove is 20 degrees or more and 45 degrees or less. Therefore, the inclination angle θ of the side wall surface of the groove 3 is set with respect to the axis of the small flame hole 4. 10 degrees to 45 degrees.
A combustion plate having an inclination angle of the groove of 20 degrees or more and 45 degrees or less is suitable for 13A standard gas. The combustion plate is for 13A standard gas and has a surface load of 170 kW / m²It is used in less than.
[0053]
The depth H of the groove has been described as 1.5 mm or more in the above-described embodiment, but it can be used as shown in Embodiment 8 even when the depth is 1.4 mm in a test with 13A and BP30 gas. It turned out to be. 16 to 18 show that Examples 7 and 8 show that the combustion noise is reduced and the surface temperature with respect to the amount of combustion is within the use range. Therefore, it is preferable that the groove 3 has a depth of 1.4 mm or more. The small flame hole 4 has a length L that can secure a preheating region of the premixed gas. About the length L which can ensure the preheating area | region of this premixed gas, it carries out similarly to the said Example.
[0054]
From the above, in order to be able to control the combustion amount in a wide range from the low load range to the high load range without depending on the gas type, the inclination angle θ is set to 10 ° to 45 ° within the range of LPG, LNG. An inclination angle θ suitable for dealing with.
According to this invention, the combustion amount can be controlled in a wide range from a low load range to a high load range without depending on the gas type, and combustion noise is eliminated. It also saves fuel and CO₂  It also leads to reduction of the amount generated.
The infrared burner 21 of the present invention includes the combustion plate having the above-described configuration, and can improve the combustion efficiency.
[0055]
Next, the characteristics in the low load region between the combustion plates of Examples 6 to 8 of the present invention and the combustion plate of the conventional example 2 are compared. The test method for comparing these characteristics is as follows.
Low load area (surface load: 135 to 170 kW / m²  On the other hand, both combustion characteristics using 13A and LPG will be described. In particular, it relates to combustion noise and surface temperature characteristics.
[0056]

Surface temperature measurement
When 5 minutes passed after the start of combustion, the temperatures near the center of the left and right plate surfaces were measured, and the average value was defined as the surface temperature. For the measurement of the surface temperature, a portable digital radiation thermometer (Daido Special Steel Star Thermo DS-06CF) was used. Set the emissivity to 0.50.
[0057]
The properties and composition of 13A gas (LNG) and BP30 gas (LPG) used in the experiment are as follows.
Properties of 13A gas
Total calorific value 46,055 kJ / m³
An example of the composition of 13A gas is shown in Table 5.
[0058]
[Table 5]

[0059]
Properties of BP30 gas
Total calorific value (25 ° C., 1 atm): 49735 kJ / kg
An example of the composition of BP gas is shown in Table 6.
[0060]
[Table 6]

[0061]
The outline of the combustion plate of Conventional Example 2 used in the experiment and the combustion plate of the present invention will be described.
FIG. 15 shows the dimensions of an example of the combustion plate of Conventional Example 2. In the conventional combustion plate, a number of flame holes are formed in the groove and the projection itself.

FIG. 13 shows the dimensions of an example of the combustion plate of the present invention.

Examples 6, 7, and 8 are cases in which the inclination angle θ of the combustion plate and the depth H of the groove are changed.

The conventional example 2 has substantially the same depth and inclination angle as the conventional groove 1, but the flame hole diameter is greatly different. In Example 6 and Example 3, the depth of the groove, the inclination angle, the flame hole diameter, and the hole area ratio are all the same.
[0062]
Table 7 shows the change in time over which the combustion sound after ignition continued with respect to the change in the gas type and the combustion amount.
[0063]
[Table 7]

[0064]
In Table 7, in Conventional Example 2, since the groove was shallow and the angle of the inclined surface of the top of the weight type at the top of the groove was 66 degrees, no combustion noise was generated in both 13A gas and BP30 gas. .
In Example 6, when 13A is used, the surface load is 155 kW / m.²  In the following low combustion, a combustion noise was remarkably generated and did not stop even after 10 minutes or more after the start of combustion. On the other hand, when Example 6 was burned with BP30 gas, the surface load was 153 kW / m.²  In the following cases, a combustion noise was generated, and the combustion noise disappeared when about 40 seconds passed after ignition.
[0065]
Hereinafter, the combustion noise that changes depending on the inclination angle θ of the side wall surface of the concave groove, the gas type, and the combustion amount will be considered.
FIGS. 14 (a), (b), and (c) are schematic diagrams showing a balanced state of the gas ejection speed and the flame propagation speed in the downstream area of the flame hole and in the groove, and FIG. In the case of 1650 W, FIG. 14 (b) shows the combustion state, ejection speed, and combustion speed in the case of 13A gas 1650 W in Example 7, and FIG. 14 (c) shows the case of BP30 gas 1630 W in Example 6.
14 (a) and 14 (b), a is red hot, b is somewhat red hot, c is hardly red hot, and in FIG. 14 (c), c is red hot and b is red hot to some extent. , A indicates that it is hardly red-hot. In FIGS. 14 (a), (b), and (c), the upward arrow indicates the ejection speed, and the downward arrow indicates the combustion speed.
[0066]
Consideration of the presence or absence of combustion noise for changes in the tilt angle θ
Combustion amount of 1650 W (155 kW / m) with the combustion plate of Example 6 using 13 A gas²  7), only the tip “a” of the projection part which was a flameless hole was red hot, and the root “c” was not red hot as shown in FIG.
As shown in FIG. 14 (b), when Example 7 was burned under the same conditions, it was red hot from the tip of the protrusion to the root c.
[0067]
In Example 6, since the inclination angle θ is small, the flow velocity of the gas is high also at the protrusion root c, so that the combustion position (flame surface) has shifted to the downstream side, and it can be said that the protrusion root c did not become red hot. . Therefore, it is considered that the mixed gas stays at the base of the protrusion, which leads to generation of combustion noise. On the other hand, in Example 7 and Example 8, with the increase in θ, the flame surface shifted to the vicinity of the protrusion root (upstream side) from the balance between the combustion speed and the gas flow velocity, and red heat was generated up to the protrusion root c. I can say that. The fact that the combustion has started near the base of the protrusion coincides with a decrease in the time until the combustion noise disappears after the start of combustion as the amount of combustion increases.
[0068]
Consideration on change of gas type and presence of combustion noise
Combustion amount 1630W (153 kW / m) using BP30 gas as compared with Example 6.²), The protrusion tip a was slightly dark and the protrusion root c was red hot. Since BP30 gas has a higher combustion speed than 13A gas (the combustion speed at the air ratio λ = 1.05 is 13A gas: about 33 cm / s and BP30 gas: about 39 cm / s, respectively), even in Example 6, the flame It can be said that the protrusion root c was red hot without the surface moving downstream. As will be described later, when BP30 gas was used as fuel, no significant combustion noise was generated even when the combustion load was further reduced.
Therefore, when using a gas having a slow combustion rate such as 13A gas, the inclination angle θ needs to be larger than 15 degrees.
[0069]
Relationship between combustion load and combustion plate surface temperature
Table 8 shows the relationship between the combustion amount and the plate surface temperature in 13A gas and BP30 gas.
[0070]
[Table 8]

[0071]
FIG. 16 shows the relationship between the combustion amount in the low load region and the plate surface temperature when 13A gas is used. FIG. 17 shows the relationship between the amount of combustion in the low load region and the plate surface temperature when BP30 gas is used.
[0072]
When using 13 A gas, 1,812 W (surface load: 170 kW / m²  ), The surface angle of the one having the smaller inclination angle θ of Example 6 (Example 6 has a smaller inclination angle, and the inclination angle becomes larger in the order of Example 7 and Example 8) reached a higher temperature. 1,650W (Surface load: 155kW / m² ) In the following low load region, the surface temperature of Example 6 dropped to about Example 8 (FIG. 16). At this time, rather, the surface temperature of Example 7 was higher than that of Example 6. 1,650 W with 13 A gas (surface load: 155 kW / m² ) In the case of the following low load combustion, in Example 6, only the diamond tip a was red hot. This indicates that the flame surface has shifted to the downstream side because the burning speed of 13A gas is low.
[0073]
Next, when BP30 gas is used, 135 to 167 kW / m²  In the whole area, the surface temperature is higher when the inclination angle θ of Example 6 is smaller (Example 6 has a smaller inclination angle, and the inclination angle becomes larger in the order of Example 7 and Example 8). Also in Example 6, there was no reversal phenomenon in the relationship between the inclination angle θ and the reached surface temperature that occurred when 13A gas was burned at a low load (FIG. 17). As described above, the protrusion inclination angle θ affects the combustion noise and the surface temperature in accordance with the gas combustion rate (gas type) and the surface load. Therefore, it is necessary to optimize θ in consideration of them.
[0074]
From FIG. 16, in 13A gas combustion, Example 7 is 152 kW / m.² The surface temperature when burned at such a low load is 170 kW / m in the conventional example 2.² In the same manner as in the case of BP30 gas combustion, Example 7 is 146 kW / m from FIG.² The surface temperature when burned at 167 kW / m in conventional example 2² It can be seen that it is about the same as when burned with. 16 and 17 are 167 kW / m.² From the comparison, it can be said that the plate surface temperature tends to be higher during LPG combustion with a high combustion rate. From this, it can be said that Example 7 (θ = 27 degrees) has an energy saving effect of 10% or more as compared with Conventional Example 2 (θ = 0 degrees), and in particular, in Example 6 ( (θ = 15 degrees), a further energy saving effect can be estimated. In both cases, 13A and LPG, this effect according to Example 8 (θ = 45 degrees) is hardly sufficient.
[0075]
Combustion amount controllability by the plate etc. of this application
FIG. 18 shows changes in plate surface temperature when the amount of combustion is changed using various plates.
According to Example 6 (θ = 15 degrees) to Example 7 (θ = 27 degrees), the combustion amount can be controlled in a wide range, and the surface temperature is significantly higher than that of the conventional plate (Conventional Example 2). The temperature rises rapidly. FIG. 18 shows the result when LPG is used as fuel, but the same result is obtained when 13A is used as fuel.
However, in Example 6, when 13A is used as fuel, the combustion noise becomes significant in the range of combustion amounts of 1,400 to 1650 W, and the surface temperature also falls from Example 7. Therefore, with the plate having the inclination angle θ larger than that of Example 6 (15 degrees) and smaller than Example 8 (45 degrees), the effect of the present invention can be obtained regardless of the difference in the burning speed of the fuel used. There is an advantage that it can be used as (no choice of gas type).
[0076]
According to the present invention, for example, when a fuel with a slow combustion speed such as 13A (city gas) is used and the combustion load is suppressed, the generation of combustion noise is suppressed, and the amount of combustion is within a range comparable to that of the sixth embodiment. In addition, the plate surface temperature reaches the same level as in the conventional example 2 even at a low load of about 6 to 12% as compared with the conventional example 2.
That is, according to the present invention, the combustion amount can be controlled in a wide range from the low load range to the high load range without depending on the gas type, and combustion noise is eliminated. It also saves fuel and CO₂  It also leads to reduction of the amount generated. Furthermore, energy saving can be easily achieved by replacing the existing burner.
[0077]
Although an example of the embodiment of the present invention has been described above, the present invention is not limited to such an embodiment, and can of course be implemented in various forms without departing from the gist of the present invention. is there. In the above-described experiment, the maximum combustion amount was 4184 W (the surface temperature at that time reached the maximum temperature of about 1180 ° C. in Examples 3 and 5). It takes into account the heat resistance temperature of the ceramic plate used in the examples, and if the present invention is further implemented using a high heat resistance plate, it is possible to enter a higher combustion amount region, which is even higher. A surface temperature (greater turndown ratio) is obtained.
[0078]
【The invention's effect】
The present invention is implemented in the form as described above, and has the effects described below.
[0079]
In the combustion plate of the present invention, the cross-sectional shape in the width direction of the concave groove of the combustion plate is a trapezoidal shape with a depth that allows both sides of the wall to be red-heated by the flame during combustion and has a depth to retain the flame. Flames can be sufficiently retained by spreading the grooves in the downstream direction, and the entire surfaces of both side walls opened in the downstream direction can be red-heated, so that the combustion efficiency can be improved.
According to the combustion plate, the turndown ratio can be expanded to about 3/1 by one burner, and the surface temperature can be adjusted in the range of about 800 degrees to 1100 degrees or more.
Furthermore, the surface load for obtaining a high temperature surface of 1100 degrees or more is about 315 to 250 kW / mm.²  As a result, the fuel can be saved by about 40 to 55% compared with the conventional case, and at the same time, CO can be saved.₂  The amount generated can be reduced.
Further, if this combustion plate is used as a burner, the standing flame is eliminated even during high-load combustion, so the distance from the surface of the combustion plate to the object to be heated can be made smaller than before. Along with this, the heating efficiency is further improved, and as a result, downsizing (compacting) of the device and shortening of the processing time are realized. As a result, the degree of freedom in design is expanded.
[0080]
  The combustion plate of this invention isAn LPG plate with a fast burning rate, andInclination angle of the side wall surface of the grooveBut10 degrees to the axis of the small flame hole20WhenHas becomeByIts side wallsThe entire surface is red-hot and the combustion efficiency is best.The combustion plate is for LNG with a slow combustion rate and a surface load of 170 kW / m ² It is a combustion plate for lower load combustion, and the inclination angle of the side wall surface of the groove is 20 degrees to 45 degrees with respect to the axis of the small flame hole, so that the side wall is red hot and the combustion efficiency Can raiseAlso, the concave grooveDepth ofThe1.4mm or moreIsThus, a sufficient flame retention effect can be obtained, the side wall surface of the groove can be red-hot, and the combustion efficiency can be increased.
[0082]
Since the infrared burner of this invention is provided with the combustion plate which has an above-described effect, it can improve combustion efficiency. Even during high-load combustion, the standing flame is eliminated, so the distance from the burner surface to the object to be heated can be made smaller than before, and accordingly heating efficiency can be further improved, and the amount of combustion Is variable, so it is easy to use. As a result, downsizing (compacting) of the apparatus and shortening of processing time can be realized.
[0083]
  The combustion plate according to the present invention comprises a plurality of concave grooves formed in a lattice shape, a large number of polyhedral-shaped protrusions having side surfaces formed by the concave grooves, and a plurality of small protrusions formed on the bottom surface of the concave grooves. Combustion plate provided with a flame hole, or a large number of chevron protrusions formed in a polyhedral shape and extending upward, a concave groove forming a side surface of the chevron protrusion, and a large number of small flames formed on the bottom surface of the concave groove A groove is formed in the combustion plate equipped with holes so that the width widens upward from the bottom to retain the flame.In addition, by setting the depth of the side wall surface of the concave groove to 1.4 mm or more, a sufficient flame retention effect can be obtained, the side wall surface of the concave groove can be heated red, and the combustion efficiency can be increased. Can do.
[0085]
  The combustion plate according to the present invention corresponds to LPG having a high combustion rate by setting the inclination angle of the side wall surface of the concave groove to 10 to 20 degrees with respect to the axis of the small flame hole.LetTheOf this inventionFor the combustion plate, the inclination angle of the side wall surface of the groove is relative to the axis of the small flame hole.20From 45 degrees to 45 degrees, the entire surface is red hot and the combustion efficiency is best.FireIt is possible to deal with LNG with a slow baking rate, for example, 13A. Moreover, by making the depth of the side wall surface of the concave groove 1.4 mm or more, a sufficient flame retention effect can be obtained, the side wall surface of the concave groove can be red-hot, and the combustion efficiency is increased. Can do.
  According to this invention, the combustion amount can be controlled in a wide range from a low load range to a high load range without depending on the gas type, and combustion noise is eliminated. It also saves fuel and CO₂  It also leads to reduction of the amount generated. Furthermore, energy saving can be easily achieved by replacing the existing burner.
  Since the infrared burner of this invention is provided with the combustion plate which has an above-described effect, it can improve combustion efficiency.
[Brief description of the drawings]
FIG. 1 is a partially enlarged plan view of a combustion plate according to the present invention.
FIG. 2 is a cross-sectional view showing a first embodiment of a combustion plate of the present invention.
3 is a sectional view showing Example 2. FIG.
4 is a cross-sectional view showing Example 3. FIG.
5 is a cross-sectional view showing a combustion plate of Conventional Example 1. FIG.
FIG. 6 is a sectional view showing a gas burner equipped with the infrared burner of the present invention equipped with the combustion plate.
FIG. 7 is an explanatory view showing a food baking apparatus in which a large number of infrared burners are arranged on a conveyor.
FIG. 8 is a graph showing surface temperature characteristics obtained with a combustion plate shape.
FIG. 9 is a graph showing a synergistic effect of the plate shape and the protective wire mesh.
FIG. 10 is a graph showing the surface temperature when the flame hole length is 7.5 mm.
FIG. 11 is a graph showing the depth from the upper surface of the combustion plate and the thermocouple temperature.
FIG. 12 is a partially enlarged plan view showing Example 3 of the combustion plate.
FIG. 13 is an enlarged view of the flat surface and the side surface of the protrusion of the third embodiment.
14A and 14B are schematic diagrams showing a balance state of gas ejection speed and flame propagation speed in the downstream area of the flame hole part and in the groove part. FIG. 14A shows the case of 13A gas in Example 6, and FIG. In the case of gas, (C) shows the case of BP30 gas of Example 6.
FIG. 15 is an enlarged view of a flat surface and a side surface of a protruding portion of Conventional Example 2;
FIG. 16 is a graph showing the relationship between the amount of combustion and the plate surface temperature in a low load region when 13A gas is used.
FIG. 17 is a graph showing the relationship between the amount of combustion and the plate surface temperature in a low load region when BP30 gas is used.
FIG. 18 is a graph showing the relationship between the amount of combustion and the surface temperature when LPG is used.
[Explanation of symbols]
1 Combustion plate
2 chevron
3 groove
3a Side wall surface
4 Small flame hole
21 Infrared burner

Claims (7)

On the surface of the combustion plate made of a refractory material, a number of rhombuses, squares, and other chevron-shaped projections with appropriate shapes and flameless holes are formed vertically and horizontally with concave grooves around them. In a combustion plate having a plurality of small flame holes of% to 20%,
A combustion plate characterized in that the cross-sectional shape in the width direction of the concave groove provided around the chevron is expanded in a downstream direction at an inclination angle at which both side walls can be red-heated by a flame, and has a trapezoidal depth to retain the flame. . 2. The combustion according to claim 1, wherein the combustion plate is an LPG plate having a high combustion rate, and the inclination angle of the side wall surface of the concave groove is 10 degrees to 20 degrees with respect to the axis of the small flame hole. plate. The combustion plate is for LNG with a low combustion rate and a surface load of 170 kW / m ² The combustion plate according to claim 1, wherein the combustion plate is in a lower load region, and the inclination angle of the side wall surface of the groove is 20 to 45 degrees with respect to the axis of the small flame hole. The combustion plate according to claim 1 , wherein the groove has a depth of 1.4 mm or more. An infrared burner comprising the combustion plate according to any one of claims 1 to 4 . A refractory material comprising: a concave groove formed in a lattice shape; a large number of upwardly projecting chevron-shaped protrusions whose side surfaces are formed by the concave grooves; and a large number of small flame holes formed on the bottom surface of the concave groove. A combustion plate consisting of
The said ditch | groove is formed so that a width may spread upward from a bottom face in order to make a flame stay , and the depth is 1.4 mm or more, The combustion plate characterized by the above-mentioned . Combustion plate made of a refractory material comprising a large number of chevron protrusions formed in a polyhedral shape and extending upward, a concave groove forming a side surface of the chevron protrusion, and a large number of small flame holes formed in the bottom surface of the concave groove Because
The said ditch | groove is formed so that a width may spread upward from a bottom face in order to make a flame stay , and the depth is 1.4 mm or more, The combustion plate characterized by the above-mentioned .

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