JP2004044915A

JP2004044915A - Combustion device

Info

Publication number: JP2004044915A
Application number: JP2002203192A
Authority: JP
Inventors: Akira Tsutsumi; 堤　明
Original assignee: Noritz Corp
Current assignee: Noritz Corp
Priority date: 2002-07-11
Filing date: 2002-07-11
Publication date: 2004-02-12
Anticipated expiration: 2022-07-11
Also published as: JP3940908B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a combustion device having a second heat exchanger for collecting the latent heat capable of preventing the second heat exchanger from being heated in the water stop condition during the freezing preventive operation. <P>SOLUTION: The combustion device includes a high temperature side thermo-sensor 40, a low temperature side thermo-sensor 41, and a thermo-sensor for a header part, which are monitored and when either of them indicates 5°C or less, the freezing preventive operation is started, and a heating circulation pump 23 is started, and at the same time, a thermally actuating valve at the heating terminal is opened. As a result, a heating medium flows to the first and second heat exchangers via the heating terminal. Then a bath thermally actuating valve 21 is opened. As a result, the heating medium circulates to the first and second heat exchangers via the primary side of a third heat exchanger. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、燃焼装置に関するものであり、特に燃焼ガスの潜熱を利用する熱交換器を備えた燃焼装置として好適なものである。
【０００２】
【従来の技術】
床暖房等の暖房器具と、風呂の追い焚き機能を一台の燃焼装置で賄う構造の燃焼装置が知られている。当該燃焼装置では、燃焼ガスの流路内に設けられた気・液熱交換器と、燃焼ガス流路外に設けられた液・液熱交換器を備える。そして液・液熱交換器は、気・液熱交換器の両端側を接続する様に配管されている。また液・液熱交換器には熱動弁等の開閉弁が接続されている。そして気・液熱交換器に暖房器具が接続され、液・液熱交換器には風呂が接続される。したがって気・液熱交換器を中心に考えたとき、液・液熱交換器と暖房器具は並列関係となる。また燃焼ガス流路内には、暖房機器をバイパスするバイパス流路が設けられている。なおバイパス流路についても液・液熱交換器および暖房器具と並列関係となる。
【０００３】
【発明が解決しようとする課題】
ところで、近年、省エネルギーや環境保護の観点から、従来の燃焼装置よりもさらにエネルギー効率の高い燃焼装置が切望されている。そこで、本発明者らはかかる要望を解決すべく燃焼ガスの顕熱に加えて潜熱も回収可能な潜熱回収型燃焼装置を試作した。
【０００４】
試作した潜熱回収型燃焼装置は、主として燃焼ガスの顕熱を回収する第１熱交換器と、主として潜熱を回収する第２熱交換器とを備えたものであり、従来の燃焼装置に比べて熱効率が高い。
試作した燃焼装置では、第１熱交換器と第２熱交換器は、直列的に接続され、水等の被加熱物は、第２熱交換器から入り、第１熱交換器側に流れる。また暖房機器をバイパスするバイパス流路が設けられており、当該バイパス流路は、第１熱交換器の出入り側を短絡する様に配管接続されている。また液・液熱交換器は、直列的に接続された状態における前記第１、第２熱交換器の両端側を接続する関係に配管接続され、第１熱交換器と第２熱交換器を中心に考えたとき、液・液熱交換器と暖房器具は並列関係となる。
【０００５】
バイパス流路についても液・液熱交換器および暖房器具と並列関係となる。なおパイパス流路を設ける理由は、床暖房等の暖房端末が未接続であったり、暖房端末側の熱動弁等が閉止している状態であっても暖房循環ポンプを動作させて熱媒体の循環が可能とするためである。すなわちバイパス流路は暖房機器をバイパスするものであり、第１熱交換器の入側と出側を短絡する様に配管接続されているから、床暖房等の暖房端末が未接続であったり、暖房端末側の熱動弁等が閉止している状態であっても暖房循環ポンプを動作させると熱媒体が第１熱交換器を経由して循環する。
またパイパス流路を設けるもう一つの理由は、暖房端末等に流れ込む熱媒体の量を調節するためである。
【０００６】
風呂の追い焚き側の回路は、公知のものと同一であり、ガス流路外に設けられた液・液熱交換器を備え、第１、第２熱交換器と液・液熱交換器は直列的に接続されている。また液・液熱交換器には熱動弁等の開閉弁が接続されている。
【０００７】
上記した構成の燃焼装置は、周知の燃焼装置に潜熱回収用の第２熱交換器を付加したものであり、通常運転の際には何ら問題なく動作する。しかしながら、試作機は、凍結防止運転を行う際に予期しない不具合が生じた。
すなわち寒冷地で使用する燃焼装置は、内部の水の凍結を防止するために、一定条件下においてバーナを燃焼させる。そして同時に気・液熱交換器に水等を循環させる。その結果、器具内の水が加熱され、さらに暖房端末（床暖房器具等）を循環して凍結が防止される。また暖房端末の開閉弁等が閉じている場合には、第１熱交換器をバイパスするバイパス流路を水が循環する。
【０００８】
ところが、本出願人等が試作した燃焼装置では、バイパス流路は、第１熱交換器の両端側だけを短絡するものであるから、暖房端末の開閉弁が閉じていると、第２熱交換器側に通水されない。そのため凍結防止運転の際に、第２熱交換器が止水状態で加熱されることとなり、当該熱交換器内に残留する水が沸騰して異音を発生するという不具合が生じた。
そこで第１熱交換器だけでなく、第２熱交換器をもバイパス流路で短絡させる構成も検討したが、当該流路構成によると第２熱交換器の入力側に高温の湯等が流れ込むタイミングが生じ、熱効率の低下を招く為好ましくない。
【０００９】
そこで本発明は、実験によって発見された不具合を解消することを課題とするものであり、凍結防止運転時における、第２熱交換器の止水状態での加熱を防ぐことができる燃焼装置の開発を課題とするものである。
【００１０】
【課題を解決するための手段】
上記した課題を解決するための請求項１に記載の発明は、燃料を燃焼する燃焼手段と、当該燃焼手段において発生した燃焼ガスと熱交換を行う第１熱交換器と、第１熱交換器よりも燃焼ガスの下流側に配置され第１熱交換器を通過した燃焼ガスと熱交換を行う第２熱交換器と、燃焼ガスの流路外に置かれた第３熱交換器と、ポンプと、第３熱交換器に繋がる開閉弁を有し、前記第１、第２熱交換器は直列的に接続され、第３熱交換器は直列的に接続された状態における前記第１、第２熱交換器の両端側を接続する関係に配管接続され、さらに第１熱交換器と第３熱交換器を結ぶ間と、第２熱交換器と第１熱交換器を結ぶ間同士の間が配管接続され、所定の位置に往き口と戻り口が設けられていて液体が他の機器に対して往き来し、さらに凍結防止運転機能を備え、凍結防止運転に際してはポンプが動作すると共に燃焼手段が燃焼し、開閉弁が開いて第１及び第２熱交換器と第３熱交換器を環状に結ぶ流路を開き、燃焼が終了すると開閉弁が閉じることを特徴とする燃焼装置である。
なお凍結防止運転時におけるポンプの起動、燃焼手段への点火、および開閉弁の開動作の順序は不同であるが、通常は、ポンプが回転を開始した後に燃焼手段に対して点火される。
【００１１】
本発明の燃焼装置では、通常の気・液熱交換器たる第１熱交換器の下流に潜熱回収用の第２熱交換器が設けられている。そのため本発明の燃焼装置は、熱効率が高い。また本発明の燃焼装置においては、凍結防止運転に際して燃焼手段が燃焼すると開閉弁が開いて第３熱交換器に至る流路を開く。ここで本発明では、第３熱交換器は、直列的に接続された状態における前記第１、第２熱交換器の両端側を接続する関係に配管接続されている。そのため第１、第２熱交換器の水は、第３熱交換器を経由して循環する。そのため試作機で問題となった様な、第２熱交換器の止水状態での加熱は起こらない。
また本発明の燃焼装置では、燃焼が終了すると開閉弁が閉じるので、熱媒体の熱が風呂側に逃げることがなく、熱の無駄な放散を防ぐことができる。
【００１２】
また請求項２に記載の発明は、第３熱交換器は、浴槽の水を加熱する液・液熱交換器であることを特徴とする請求項１に記載の燃焼装置である。
【００１３】
本発明の燃焼装置では、第３熱交換器によって浴槽内の湯水を追い焚きすることができる。
【００１４】
また請求項３に記載の発明は、第１、第２熱交換器は、暖房装置に接続されていることを特徴とする請求項１又は２に記載の燃焼装置である。
【００１５】
本発明の燃焼装置では、第１、第２熱交換器によって室内の温度を適温に保つことができる。
【００１６】
【発明の実施の形態】
以下、本発明の一実施形態である燃焼装置について図面を参照しながら説明する。図１は、本実施形態の燃焼装置の配管系統図である。図２は、図１の配管系統図の要部を抜き出して簡略化した配管系統図である。図３は、本発明の燃焼装置の動作を説明するフローチャートである。
【００１７】
本発明の燃焼装置は、内部に独立した二系統の缶体及び配管系統を備える。すなわち図１において、右側の缶体１は、給湯用であり、左側の缶体２は、風呂及び暖房器具用に使用される。
【００１８】
本発明は風呂及び暖房器具用の配管系統に特徴があるので、当該部位の配管に重点を絞って説明する。
すなわち缶体２は、大別して加熱部３と、加熱部３において発生した燃焼ガスと熱媒体（水等）とが熱交換を行う熱交換部４と、熱交換部４を通過した燃焼ガスを缶体２の外部に排出する排気部５とから構成されている。
【００１９】
加熱部３は、ガスや灯油等の液体燃料を燃焼するバーナ（燃焼手段）６と燃焼空間部７とから構成されている。バーナ６において発生した高温の燃焼ガスは、燃焼空間部７を通過し、熱交換部４へと流入する。
【００２０】
熱交換部４は、燃焼空間部７に連続した熱交換器８（第１熱交換器）と、熱交換器１０（第２熱交換器）とが直列的にに配置されたものである。すなわち本実施形態では、燃焼装置は、第１熱交換器８と、第２熱交換器１０という２基の熱交換器を持つ。そして第１熱交換器８と、第２熱交換器１０はいずれも燃焼ガスの流路内にあり、両者は燃焼ガスの流路に対して直列に配置されている。
【００２１】
熱交換器８は、主要部分が銅製であり、主として前記燃焼ガスの顕熱を回収するものであり、内部に湯水や不凍液などの熱媒体が流れるフィンアンドチューブ方式の熱交換器である。熱交換器８は、燃焼空間部７に連続した位置に設けられており、燃焼空間部７から熱交換部３内に流入した高温の燃焼ガスと熱交換を行う。
【００２２】
熱交換器１０は、熱交換器８において熱交換を行った後の燃焼ガスと熱交換を行うものである。熱交換器１０は、主として燃焼ガスの持つ潜熱を回収するものである。燃焼ガスが保有する熱の中で、熱交換器８において回収されなかった熱エネルギーの大部分が熱交換器１０において回収される。そのため、熱交換器１０を通過した燃焼ガスは、１００℃以下程度の低温となる。熱交換器１０は、主要部分がステンレス製等であり、熱交換器８に比べて防錆特性に優れている。そのため、熱交換器１０は、燃焼ガスから潜熱を回収する際に発生する酸性の凝結水に晒される雰囲気下に配置されてもほとんど腐食されず、錆が発生しない。
【００２３】
また風呂側の回路に属する部材として、第３熱交換器２０、風呂熱動弁２１、及び風呂水循環ポンプ２２がある。一方、暖房側の回路に属する部材として、暖房循環ポンプ２３、膨張タンク２４、及びバイパス熱動弁２５がある。
そして前記した第１熱交換器８と第２熱交換器１０は、流路（熱媒流路　具体的には水路）が直列に接続され、その間に膨張タンク２４及び暖房循環ポンプ２３が接続されている。また暖房端末側をバイパスするために設けられたバイパス流路２６が設けられている。なお第１熱交換器８と第２熱交換器１０を中心に考えたとき、第３熱交換器２０、暖房端末側およびバイパス流路２６は互いに並列関係にある。
【００２４】
バイパス流路２６は、第１熱交換器８の入側と出側を短絡するものであり、第１熱交換器８と第３熱交換器２０を結ぶ１−３熱交連結路と、第２熱交換器と第１熱交換器を結ぶ２−１熱交連結路の間がバイパス流路２６を介して配管接続されている。
当該バイパス流路２６にバイパス熱動弁２５が設けられている。またさらにバイパス熱動弁２５をバイパスするサブバイパス流路２７が設けられている。
【００２５】
また燃焼装置には暖房往き口（高温側）３０と暖房戻り口３１及び暖房往き口（低温側）３４が設けられている。そして暖房戻り口３１が第２熱交換器１０の入り側に接続されている。また第２熱交換器１０の出側は膨張タンク２４に接続され、さらに暖房循環ポンプ２３を経て第１熱交換器８の入り側に接続されている。また第１熱交換器８の出側は、高温側暖房往き口３０に接続されている。また暖房循環ポンプ２３の出側と第１熱交換器８の入り側の間が分岐され、暖房往き口（低温側）３４に接続されている。
膨張タンク２４の入り側と第１熱交換器８の出側との間に前記したバイパス流路２６があり、当該バイパス流路２６にバイパス熱動弁２５が設けられている。バイパス流路２６は第１熱交換器８の両端を短絡するものであり、第２熱交換器１０は短絡されない。したがって第１熱交換器８、バイパス流路２６、膨張タンク２４及び暖房循環ポンプ２３によって一つの環状の循環回路が構成される。
すなわち本実施形態では、第１熱交換器８の出側と暖房往き口（高温側）３０の間に分岐部４８が設けられてバイパス流路２６が設けられ、バイパス流路２６の他端側は、第２熱交換器１０と膨張タンク２４の間に接続されている。
【００２６】
また図１，２の様に、第１及び第２熱交換器８，１０に対して直列的に第３熱交換器２０が設けられている。第３熱交換器２０は、第１及び第２熱交換器８，１０で加熱された水と、風呂の湯水との間で熱交換するものであり、液・液型の熱交換器である。したがって第３熱交換器２０には一次側（熱媒体通過側）と二次側（風呂水循環側）があり、それぞれに入り側と出側がある。
【００２７】
第３熱交換器２０は、第２及び第１熱交換器に対して直列的且つ環状に配されたものであり、第３熱交換器は、直列的に接続された状態における前記第１、第２熱交換器の両端側を短絡して接続する関係に配管接続されている。
【００２８】
すなわち第３熱交換器２０の一次側の一方の接続口は、第１熱交換器８の出側と暖房往き口３０の間に接続されている。具体的には、第１熱交換器８の出側と暖房往き口３０の間に分岐点４６が設けられ、第３熱交換器２０の一次側の他方の接続口（入り側）は当該分岐点４６に接続されている。なお本発明においては、分岐点４６，４８のいずれが上流であるか下流であるかは問題ではない。
【００２９】
第３熱交換器２０の一次側の他方の接続口は、暖房戻り口３１から第２熱交換器に至る間に接続されている。すなわち暖房戻り口３１から第２熱交換器に至る間に分岐点４５が設けられ、第３熱交換器２０の一次側の他方の接続口から延長された３２配管が合流している。
【００３０】
一方、第３熱交換器２０の二次側は、風呂戻り口３３と風呂往き口３５に接続され、風呂戻り口３３と第３熱交換器２０の間には風呂水循環ポンプ２２が設けられている。
暖房往き口（高温側）３０及び暖房戻り口３１は、ファンコンベクタ等の高温の熱媒体を使用する暖房端末に接続される。一方、暖房往き口（低温側）３４及び暖房戻り口３１の間には、床暖房装置等の低温の熱媒体を使用する暖房端末に接続される。風呂往き口３５及び風呂戻り口３３は、図示しない浴槽に接続される。
【００３１】
また燃焼装置には、高温側温度センサー４０と、低温側温度センサー４１が設けられている。すなわち高温側温度センサー４０は、第１熱交換器８の出口側に設けられている。高温側温度センサー４０は、第１熱交換器８を出た直後の熱媒温度を測定するものである。
低温側温度センサー４１は膨張タンク２４の底部に設けられている。低温側温度センサー４１は第２熱交換器１０を出て、膨張タンク２４に入った熱媒体の温度を測定するものである。
【００３２】
そしてファンコンベクタや床暖房等の暖房機器を使用する際には、缶体２内の下部に設けられた送風機によって缶体２内に送風しつつ、バーナ６で火炎を発生させる。また同時に暖房循環ポンプ２３を動作させる（暖房循環ポンプ２３は通常運転時には常時動作している）。その結果、暖房端末を経由して水等の熱媒体が第１及び第２熱交換器８，１０に流れる。
すなわち端末側から暖房戻り口３１を経て熱媒体が戻り、最初に第２熱交換器１０を流れる。第２熱交換器１０によってある程度の温度に加熱された熱媒体は、膨張タンク２４と暖房循環ポンプ２３を経た後に第１熱交換器８側と暖房往き口（低温側）３４側に分岐される。そして第２熱交換器１０によってある程度の温度に加熱された熱媒体の一部は暖房往き口（低温側）３４から排出され、低温の熱媒体を使用する床暖房装置等に送られる。また第２熱交換器１０を出た熱媒体の残部は、第１熱交換器８の入り、さらに加熱される。そして第１熱交換器８を出た熱媒体は、暖房往き口（高温側）３０からファンコンベクタ等の高温を要する暖房端末に送られ、室内等を温める。
【００３３】
なお本実施形態では、二つの暖房往き口３０，３１から吐出される熱媒体の割合を、バイパス流路２６に設けられたバイパス熱動弁２５の開閉によって調節している。すなわちバイパス熱動弁２５を全開にすると、第１熱交換器８を出た熱媒体の多くがバイパス流路２６を流れて膨張タンク２４側に戻る。その結果、暖房往き口（高温側）３０から排出される熱媒体の量が減少し、暖房往き口（低温側）３４から排出される熱媒体の量が増大する。逆に、バイパス熱動弁２５を閉止すると、第１熱交換器８を出た熱媒体の多くが暖房往き口（高温側）３０から排出されるので、暖房往き口（高温側）３０から排出される熱媒体の量が増大し、暖房往き口（低温側）３４から排出される熱媒体の量が減少する。
【００３４】
なお本実施形態では、二つの熱交換器８，１０の内、第１熱交換器８の出入口だけをバイパス流路２６で短絡し、第２熱交換器１０は短絡しないが、第２熱交換器１０についてもバイパス流路で短絡させる構成とすると、第２熱交換器に流入する熱媒体の温度が高くなり過ぎ、第２熱交換器の熱効率が低下してしまうという不具合がある。特にバイパス熱動弁２５を開いて第１熱交換器１０を出た熱媒体を上流側に戻す際、第１、第２熱交換器８，１０の双方を短絡させる構成とすると、第１熱交換器１０を出た高温の熱媒体が直接的に第２熱交換器１０に流れ込んでしまい、第２熱交換器１０の熱効率を低下させてしまう。そのため第２熱交換器８，１０を短絡する構成は、採用できない。
【００３５】
浴槽内の湯水を加熱する際には風呂水循環ポンプ２２を起動し、風呂熱動弁２１を開く。その結果、熱媒体が第３熱交換器側２０の一次側に流れ、同二次側には浴槽内の水が流れる。そして熱媒体と浴槽内の水の間で熱交換が行われ、浴槽内の湯水が加熱される。
すなわち風呂熱動弁２１を開くと、第３熱交換器側２０の一次側の流路が開放される。より具体的には、第３熱交換器側２０を含む並列流路たる、分岐点４６，４５間が連通する。その結果、暖房循環ポンプ２３によって加圧され、第１熱交換器８を通過した熱媒が、分岐点４６から分岐路４７に入り、第３熱交換器側２０を流れ、さらに分岐流路３２を流れて分岐点４５から暖房戻り口３１側の流路に入る。そして再度第２熱交換器１０に流れ込む。
一方、第３熱交換器側２０の二次側には、風呂水循環ポンプ２２によって浴槽内の水が流れ込むので、第３熱交換器側２０で熱交換が行われ、二次側の浴槽水が加熱される。
【００３６】
次に凍結防止運転について説明する。凍結防止運転は、燃焼装置内の温度又は図示しないヘッダーの温度が所定の温度以下となった事を契機として開始される。すなわち図３に示すフローチャートにおいて、ステップ１，２で高温側温度センサー４０と、低温側温度センサー４１及びヘッダー部の温度センサーを監視し、これらのいずれかが５℃以下を示すと凍結防止運転が開始される。
具体的には、ステップ３に移行して暖房循環ポンプ２３が起動され、同時に暖房端末の熱動弁（図示せず）が開かれる。その結果、暖房端末を経由して第１、第２熱交換器に熱媒体が流れる。
【００３７】
続いてステップ４に移行し、風呂熱動弁２１が開かれる。その結果第３熱交換器２０の一次側に熱媒体が流れる。
ここで前記した様にステップ３で暖房端末を開くことによって暖房端末を経由して第１、第２熱交換器に熱媒体が流れるから、あえてステップ４で第３熱交換器２０の一次側に熱媒体を流す必要性が低い様にも思われるが、本実施形態では、ステップ４で第３熱交換器２０の一次側に熱媒体を流す。
この理由は、暖房端末の元弁が閉じていたり、暖房端末自体が繋がれていない様な場合もあり得るためであり、この様な状況下においては、第２熱交換器１０側に熱媒体が流れないからである。そこで本実施形態では、ステップ４で風呂熱動弁２１を開いて第３熱交換器２０の一次側に熱媒体を流し、第３熱交換器２０の一次側を経由して第１、第２熱交換器８，１０に熱媒体を循環させている。すなわちステップ４で風呂熱動弁２１が開かれると、第１及び第２熱交換器８，１０と第３熱交換器２０を環状に結ぶ流路が開き、第１、第２熱交換器に熱媒体が流れる。
【００３８】
そして続いてステップ５でバーナ（燃焼手段）６を点火する。そしてステップ６で高温側温度センサー４０が２０℃以上を示すのを待つ。
ステップ６で高温側温度センサー４０が２０℃以上となった事が確認されるとステップ７に移行し、暖房燃焼を終了すると共に風呂熱動弁２１を閉じる。
ここで風呂熱動弁２１を閉じるのは、熱媒体の熱が風呂側に逃げることを防ぐためである。
すなわち風呂熱動弁２１が開いており、さらに風呂水循環ポンプ２２が起動すると第３熱交換器２０内で熱交換が行われ、熱媒体の熱が風呂側に逃げる。そのため熱媒体の温度が急速に低下し、上記した凍結防止の為の燃焼（暖房燃焼）を頻繁に行う結果となる。そこで本実施形態では、このような事態を防ぐために、暖房燃焼が終了すると風呂熱動弁２１を閉じる。
【００３９】
そしてステップ８に移行し、５分経過を待つ。５分が過ぎて機器内に熱媒体が行き渡り、機器内の温度が上昇すると、ステップ９に移行して端末熱動弁を閉じる。そして暖房循環ポンプ２３をポスト循環した後、暖房循環ポンプ２３を停止し、ステップ１に戻る。
【００４０】
【発明の効果】
以上説明した様に、本発明の燃焼装置では、潜熱回収用の第２熱交換器が設けられているので熱効率が高い。また本発明の燃焼装置では、凍結防止運転に際して燃焼手段が燃焼すると開閉弁が開いて、第１、第２熱交換器に対してこれらを短絡する関係にある第３熱交換器に至る流路を開く。その結果、第１、第２熱交換器の水等は、第３熱交換器を経由して循環する。そのため本発明の燃焼装置では、凍結防止運転の際に、第２熱交換器が止水状態で加熱されることが防止される。
また本発明の燃焼装置では、燃焼が終了すると開閉弁が閉じるので、熱媒体の熱が風呂側に逃げることがなく、熱の無駄な放散を防ぐことができる。
【００４１】
さらに請求項２に記載の燃焼装置では、第３熱交換器によって浴槽内の湯水を追い焚きすることができる。
【００４２】
また請求項３に記載の燃焼装置では、第３熱交換器によって室内の温度を適温に保つことができる。
【図面の簡単な説明】
【図１】本実施形態の燃焼装置の配管系統図である。
【図２】図１の配管系統図の要部を抜き出して簡略化した配管系統図である。
【図３】本発明の燃焼装置の動作を説明するフローチャートである。
【符号の説明】
２　缶体
３　加熱部
８　第１熱交換器
１０　第２熱交換器
２０　第３熱交換器
２１　風呂熱動弁
２２　風呂水循環ポンプ
２３　暖房循環ポンプ
２４　膨張タンク
２５　バイパス熱動弁
２６　バイパス流路[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a combustion device, and is particularly suitable as a combustion device provided with a heat exchanger utilizing latent heat of combustion gas.
[0002]
[Prior art]
2. Description of the Related Art A combustion device having a structure in which a heating device such as a floor heater and a bath reheating function are provided by a single combustion device is known. The combustion device includes a gas-liquid heat exchanger provided inside the combustion gas flow path and a liquid-liquid heat exchanger provided outside the combustion gas flow path. The liquid / liquid heat exchanger is connected so as to connect both ends of the gas / liquid heat exchanger. An on-off valve such as a thermal valve is connected to the liquid / liquid heat exchanger. A heating device is connected to the gas-liquid heat exchanger, and a bath is connected to the liquid-liquid heat exchanger. Therefore, when the gas-liquid heat exchanger is mainly considered, the liquid-liquid heat exchanger and the heater have a parallel relationship. In the combustion gas passage, a bypass passage that bypasses the heating device is provided. The bypass flow path also has a parallel relationship with the liquid / liquid heat exchanger and the heating appliance.
[0003]
[Problems to be solved by the invention]
By the way, in recent years, from the viewpoint of energy saving and environmental protection, there has been a long-awaited desire for a combustion device having higher energy efficiency than a conventional combustion device. Therefore, the present inventors have prototyped a latent heat recovery type combustion apparatus capable of recovering latent heat in addition to sensible heat of combustion gas in order to solve such a demand.
[0004]
The prototype latent heat recovery type combustion device includes a first heat exchanger that mainly recovers the sensible heat of the combustion gas, and a second heat exchanger that mainly recovers the latent heat. High thermal efficiency.
In the prototype combustion device, the first heat exchanger and the second heat exchanger are connected in series, and an object to be heated such as water enters from the second heat exchanger and flows toward the first heat exchanger. In addition, a bypass flow path that bypasses the heating device is provided, and the bypass flow path is connected by piping so as to short-circuit the entrance and exit sides of the first heat exchanger. Further, the liquid-liquid heat exchanger is connected by piping so as to connect both ends of the first and second heat exchangers in a state of being connected in series, and connects the first heat exchanger and the second heat exchanger. When considered at the center, the liquid-liquid heat exchanger and the heater are in a parallel relationship.
[0005]
The bypass flow path also has a parallel relationship with the liquid / liquid heat exchanger and the heater. The reason for providing the bypass path is that the heating circulation pump is operated even when the heating terminal such as the floor heating is not connected or the heating valve on the heating terminal side is closed. This is to enable circulation. That is, the bypass flow path bypasses the heating equipment, and is connected by piping so as to short-circuit the input side and the output side of the first heat exchanger, so that a heating terminal such as floor heating is not connected, When the heating circulation pump is operated, the heat medium circulates via the first heat exchanger even when the heat valve on the heating terminal side is closed.
Another reason for providing a bypass channel is to adjust the amount of heat medium flowing into a heating terminal or the like.
[0006]
The circuit on the reheating side of the bath is the same as the known one, and includes a liquid / liquid heat exchanger provided outside the gas flow path. The first and second heat exchangers and the liquid / liquid heat exchanger They are connected in series. An on-off valve such as a thermal valve is connected to the liquid / liquid heat exchanger.
[0007]
The combustion device having the above-described configuration is obtained by adding a second heat exchanger for recovering latent heat to a known combustion device, and operates without any problem during normal operation. However, the prototype had an unexpected problem when performing the anti-freezing operation.
That is, a combustion device used in a cold region burns a burner under certain conditions in order to prevent freezing of water inside. At the same time, water and the like are circulated through the gas-liquid heat exchanger. As a result, the water in the appliance is heated and further circulated through a heating terminal (floor heating appliance or the like) to prevent freezing. Further, when the on-off valve or the like of the heating terminal is closed, water circulates in the bypass flow path that bypasses the first heat exchanger.
[0008]
However, in the combustion device prototyped by the present applicant, the bypass flow path short-circuits only both ends of the first heat exchanger. Therefore, when the on-off valve of the heating terminal is closed, the second heat exchange is performed. Water is not passed to the container side. Therefore, during the antifreezing operation, the second heat exchanger is heated in a water-stop state, and the water remaining in the heat exchanger boils to generate abnormal noise.
Therefore, a configuration in which not only the first heat exchanger but also the second heat exchanger is short-circuited in the bypass flow path was examined. However, according to the flow path configuration, hot water or the like flows into the input side of the second heat exchanger. It is not preferable because timing occurs and thermal efficiency decreases.
[0009]
Therefore, an object of the present invention is to solve the problems found by experiments, and to develop a combustion device that can prevent the second heat exchanger from being heated in a water-stop state during antifreeze operation. Is the subject.
[0010]
[Means for Solving the Problems]
The invention according to claim 1 for solving the above-mentioned problem is achieved by a combustion means for burning fuel, a first heat exchanger for exchanging heat with combustion gas generated in the combustion means, and a first heat exchanger. A second heat exchanger that is disposed downstream of the combustion gas and exchanges heat with the combustion gas that has passed through the first heat exchanger, a third heat exchanger that is located outside the flow path of the combustion gas, and a pump And an on-off valve connected to a third heat exchanger, wherein the first and second heat exchangers are connected in series, and the third heat exchanger is connected in series with the first and second heat exchangers. 2 The pipes are connected so as to connect both ends of the heat exchanger, and between the first heat exchanger and the third heat exchanger and between the second heat exchanger and the first heat exchanger. Is connected to a pipe, and an outgoing port and return port are provided at predetermined positions. A stop operation function is provided, and during the anti-freezing operation, the pump operates and the combustion means burns, and the on-off valve opens to open a flow path connecting the first and second heat exchangers and the third heat exchanger in an annular manner, An on-off valve is closed when combustion is completed.
Note that the order of starting the pump, igniting the combustion means, and opening the on-off valve during the antifreeze operation is not the same, but usually the combustion means is ignited after the pump starts rotating.
[0011]
In the combustion device of the present invention, a second heat exchanger for recovering latent heat is provided downstream of the first heat exchanger, which is a normal gas-liquid heat exchanger. Therefore, the combustion device of the present invention has high thermal efficiency. In the combustion device of the present invention, when the combustion means burns during the anti-freezing operation, the on-off valve opens to open the flow path to the third heat exchanger. Here, in the present invention, the third heat exchanger is connected by piping so as to connect both ends of the first and second heat exchangers in a state of being connected in series. Therefore, the water of the first and second heat exchangers circulates via the third heat exchanger. Therefore, heating of the second heat exchanger in the water stop state, which is a problem in the prototype, does not occur.
Further, in the combustion device of the present invention, since the on-off valve is closed when the combustion is completed, the heat of the heat medium does not escape to the bath side, and wasteful heat dissipation can be prevented.
[0012]
The invention according to claim 2 is the combustion apparatus according to claim 1, wherein the third heat exchanger is a liquid / liquid heat exchanger that heats water in the bathtub.
[0013]
In the combustion device of the present invention, hot water in the bathtub can be reheated by the third heat exchanger.
[0014]
The invention according to claim 3 is the combustion device according to claim 1 or 2, wherein the first and second heat exchangers are connected to a heating device.
[0015]
In the combustion device of the present invention, the first and second heat exchangers can keep the indoor temperature at an appropriate temperature.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a combustion device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a piping diagram of the combustion device of the present embodiment. FIG. 2 is a simplified piping system diagram in which essential parts of the piping system diagram of FIG. 1 are extracted. FIG. 3 is a flowchart illustrating the operation of the combustion device of the present invention.
[0017]
The combustion device of the present invention includes two independent can bodies and a piping system inside. That is, in FIG. 1, the right can 1 is used for hot water supply, and the left can 2 is used for bath and heating appliances.
[0018]
Since the present invention is characterized by a piping system for a bath and a heating appliance, the description will be focused on the piping at the site.
That is, the can body 2 is roughly divided into a heating section 3, a heat exchange section 4 in which a combustion gas generated in the heating section 3 and a heat medium (such as water) exchange heat, and a combustion gas passing through the heat exchange section 4. And an exhaust part 5 for discharging the outside of the can body 2.
[0019]
The heating unit 3 includes a burner (combustion means) 6 for burning liquid fuel such as gas and kerosene, and a combustion space 7. The high-temperature combustion gas generated in the burner 6 passes through the combustion space 7 and flows into the heat exchange unit 4.
[0020]
The heat exchanging section 4 includes a heat exchanger 8 (first heat exchanger) and a heat exchanger 10 (second heat exchanger) that are continuous with the combustion space 7 and are arranged in series. That is, in this embodiment, the combustion device has two heat exchangers, the first heat exchanger 8 and the second heat exchanger 10. The first heat exchanger 8 and the second heat exchanger 10 are both in the flow path of the combustion gas, and both are arranged in series with the flow path of the combustion gas.
[0021]
The heat exchanger 8 is a fin-and-tube heat exchanger whose main part is made of copper and mainly recovers the sensible heat of the combustion gas, and through which a heat medium such as hot water or antifreeze flows. The heat exchanger 8 is provided at a position continuous with the combustion space 7 and exchanges heat with the high-temperature combustion gas flowing into the heat exchange unit 3 from the combustion space 7.
[0022]
The heat exchanger 10 performs heat exchange with the combustion gas after heat exchange in the heat exchanger 8. The heat exchanger 10 mainly recovers latent heat of the combustion gas. Most of the heat energy not recovered in the heat exchanger 8 is recovered in the heat exchanger 10 among the heat retained by the combustion gas. Therefore, the combustion gas that has passed through the heat exchanger 10 has a low temperature of about 100 ° C. or less. The main part of the heat exchanger 10 is made of stainless steel or the like, and is superior in rust prevention characteristics to the heat exchanger 8. Therefore, even if the heat exchanger 10 is placed in an atmosphere exposed to acidic condensed water generated when recovering latent heat from the combustion gas, it is hardly corroded and rust does not occur.
[0023]
The members belonging to the bath-side circuit include a third heat exchanger 20, a bath heat valve 21, and a bath water circulation pump 22. On the other hand, members belonging to the circuit on the heating side include a heating circulation pump 23, an expansion tank 24, and a bypass thermal valve 25.
The first heat exchanger 8 and the second heat exchanger 10 have a flow path (a heat medium flow path, specifically a water path) connected in series, and an expansion tank 24 and a heating circulation pump 23 connected therebetween. ing. Further, a bypass flow path 26 provided to bypass the heating terminal side is provided. When the first heat exchanger 8 and the second heat exchanger 10 are mainly considered, the third heat exchanger 20, the heating terminal side, and the bypass flow path 26 are in a parallel relationship with each other.
[0024]
The bypass flow path 26 is for short-circuiting the inlet side and the outlet side of the first heat exchanger 8, and includes a 1-3 heat exchange connecting path connecting the first heat exchanger 8 and the third heat exchanger 20, The piping is connected between the 2-1 heat exchange connection path connecting the second heat exchanger and the first heat exchanger via a bypass flow path 26.
A bypass thermal valve 25 is provided in the bypass passage 26. Further, a sub bypass flow path 27 that bypasses the bypass thermal valve 25 is provided.
[0025]
Further, the combustion apparatus is provided with a heating outlet (high temperature side) 30, a heating return port 31, and a heating outlet (low temperature side). And the heating return port 31 is connected to the entrance side of the second heat exchanger 10. The outlet side of the second heat exchanger 10 is connected to the expansion tank 24, and further connected to the inlet side of the first heat exchanger 8 via the heating circulation pump 23. The outlet side of the first heat exchanger 8 is connected to the high-temperature side heating outlet 30. The outlet of the heating circulation pump 23 and the inlet of the first heat exchanger 8 are branched and connected to a heating outlet (low temperature side) 34.
The bypass flow path 26 described above is provided between the inlet side of the expansion tank 24 and the outlet side of the first heat exchanger 8, and a bypass thermal valve 25 is provided in the bypass flow path 26. The bypass flow path 26 short-circuits both ends of the first heat exchanger 8, and the second heat exchanger 10 is not short-circuited. Therefore, the first heat exchanger 8, the bypass flow path 26, the expansion tank 24, and the heating circulation pump 23 form one annular circulation circuit.
That is, in the present embodiment, the branch portion 48 is provided between the outlet side of the first heat exchanger 8 and the heating outlet (high-temperature side) 30 to provide the bypass passage 26, and the other end of the bypass passage 26 Is connected between the second heat exchanger 10 and the expansion tank 24.
[0026]
Also, as shown in FIGS. 1 and 2, a third heat exchanger 20 is provided in series with the first and second heat exchangers 8 and 10. The third heat exchanger 20 exchanges heat between the water heated in the first and second heat exchangers 8 and 10 and the hot and cold water in the bath, and is a liquid-liquid type heat exchanger. . Therefore, the third heat exchanger 20 has a primary side (a heat medium passing side) and a secondary side (bath water circulation side), and has an entrance side and an exit side, respectively.
[0027]
The third heat exchanger 20 is arranged in series and annularly with respect to the second and first heat exchangers, and the third heat exchanger is connected to the first and second heat exchangers in a state of being connected in series. The pipes are connected in such a manner that both ends of the second heat exchanger are short-circuited and connected.
[0028]
That is, one connection port on the primary side of the third heat exchanger 20 is connected between the outlet side of the first heat exchanger 8 and the heating outlet 30. Specifically, a branch point 46 is provided between the outlet side of the first heat exchanger 8 and the heating outlet 30, and the other connection port (entrance side) on the primary side of the third heat exchanger 20 is connected to the branch point. Connected to point 46. In the present invention, it does not matter which of the branch points 46 and 48 is upstream or downstream.
[0029]
The other connection port on the primary side of the third heat exchanger 20 is connected between the heating return port 31 and the second heat exchanger. That is, the branch point 45 is provided between the heating return port 31 and the second heat exchanger, and the 32 pipes extending from the other connection port on the primary side of the third heat exchanger 20 join.
[0030]
On the other hand, the secondary side of the third heat exchanger 20 is connected to a bath return port 33 and a bath outlet 35, and a bath water circulation pump 22 is provided between the bath return port 33 and the third heat exchanger 20. I have.
The heating outlet (high-temperature side) 30 and the heating return port 31 are connected to a heating terminal that uses a high-temperature heat medium such as a fan convector. On the other hand, a heating terminal using a low-temperature heat medium such as a floor heating device is connected between the heating outlet (low temperature side) 34 and the heating return port 31. The bath outlet 35 and the bath return port 33 are connected to a bathtub (not shown).
[0031]
Further, the combustion device is provided with a high temperature side temperature sensor 40 and a low temperature side temperature sensor 41. That is, the high temperature side temperature sensor 40 is provided on the outlet side of the first heat exchanger 8. The high temperature side temperature sensor 40 measures the temperature of the heat medium immediately after leaving the first heat exchanger 8.
The low temperature side temperature sensor 41 is provided at the bottom of the expansion tank 24. The low-temperature side temperature sensor 41 measures the temperature of the heat medium that has exited the second heat exchanger 10 and has entered the expansion tank 24.
[0032]
When a heating device such as a fan convector or floor heating is used, a flame is generated by the burner 6 while blowing into the can 2 by a blower provided at a lower portion in the can 2. At the same time, the heating circulating pump 23 is operated (the heating circulating pump 23 is always operating during normal operation). As a result, a heat medium such as water flows to the first and second heat exchangers 8 and 10 via the heating terminal.
That is, the heat medium returns from the terminal side via the heating return port 31 and flows through the second heat exchanger 10 first. The heat medium heated to a certain temperature by the second heat exchanger 10 is branched to the first heat exchanger 8 side and the heating outlet (low temperature side) 34 side after passing through the expansion tank 24 and the heating circulation pump 23. . Then, a part of the heat medium heated to a certain temperature by the second heat exchanger 10 is discharged from the heating outlet (low-temperature side) 34 and sent to a floor heating device or the like using a low-temperature heat medium. The remainder of the heat medium that has exited the second heat exchanger 10 enters the first heat exchanger 8 and is further heated. The heat medium that has exited the first heat exchanger 8 is sent from a heating outlet (high-temperature side) 30 to a heating terminal such as a fan convector that requires a high temperature, and heats the room and the like.
[0033]
In the present embodiment, the ratio of the heat medium discharged from the two heating outlets 30 and 31 is adjusted by opening and closing the bypass thermal valve 25 provided in the bypass passage 26. That is, when the bypass heat valve 25 is fully opened, most of the heat medium that has exited the first heat exchanger 8 flows through the bypass passage 26 and returns to the expansion tank 24 side. As a result, the amount of the heat medium discharged from the heating outlet (high temperature side) 30 decreases, and the amount of the heat medium discharged from the heating outlet (low temperature side) 34 increases. Conversely, when the bypass thermal valve 25 is closed, most of the heat medium that has exited the first heat exchanger 8 is discharged from the heating outlet (high-temperature side) 30, and is discharged from the heating outlet (high-temperature side) 30. As a result, the amount of the heat medium discharged from the heating outlet (low temperature side) 34 decreases.
[0034]
In the present embodiment, of the two heat exchangers 8 and 10, only the entrance and exit of the first heat exchanger 8 are short-circuited by the bypass passage 26, and the second heat exchanger 10 is not short-circuited. If the device 10 is also configured to be short-circuited in the bypass flow path, there is a problem that the temperature of the heat medium flowing into the second heat exchanger becomes too high, and the thermal efficiency of the second heat exchanger is reduced. In particular, when the heat medium that has exited the first heat exchanger 10 is returned to the upstream side by opening the bypass heat valve 25, the first and second heat exchangers 8 and 10 may be short-circuited. The high-temperature heat medium that has exited the exchanger 10 flows directly into the second heat exchanger 10 and reduces the thermal efficiency of the second heat exchanger 10. Therefore, a configuration in which the second heat exchangers 8 and 10 are short-circuited cannot be adopted.
[0035]
When heating the water in the bathtub, the bath water circulation pump 22 is started, and the bath heat valve 21 is opened. As a result, the heat medium flows to the primary side of the third heat exchanger side 20, and the water in the bathtub flows to the secondary side. Then, heat exchange is performed between the heat medium and the water in the bathtub, and the hot water in the bathtub is heated.
That is, when the bath heat valve 21 is opened, the flow path on the primary side of the third heat exchanger side 20 is opened. More specifically, the branch points 46 and 45, which are parallel flow paths including the third heat exchanger side 20, communicate with each other. As a result, the heat medium pressurized by the heating circulation pump 23 and passing through the first heat exchanger 8 enters the branch channel 47 from the branch point 46, flows through the third heat exchanger side 20, and further flows into the branch channel 32. To enter the flow path on the heating return port 31 side from the branch point 45. Then, it flows into the second heat exchanger 10 again.
On the other hand, since the water in the bathtub flows into the secondary side of the third heat exchanger side 20 by the bath water circulation pump 22, heat is exchanged on the third heat exchanger side 20 and the bathtub water on the secondary side is discharged. Heated.
[0036]
Next, the anti-freezing operation will be described. The anti-freezing operation is started when the temperature in the combustion device or the temperature of the header (not shown) becomes equal to or lower than a predetermined temperature. That is, in the flowchart shown in FIG. 3, in steps 1 and 2, the high temperature side temperature sensor 40, the low temperature side temperature sensor 41, and the temperature sensor in the header part are monitored, and if any one of them indicates 5 ° C. or less, the antifreeze operation is performed. Be started.
More specifically, the process proceeds to step 3, where the heating circulation pump 23 is started, and at the same time, a thermal valve (not shown) of the heating terminal is opened. As a result, the heat medium flows to the first and second heat exchangers via the heating terminal.
[0037]
Subsequently, the process proceeds to step 4, where the bath heat valve 21 is opened. As a result, the heat medium flows to the primary side of the third heat exchanger 20.
As described above, since the heating medium flows to the first and second heat exchangers via the heating terminal by opening the heating terminal in step 3, the heating medium is intentionally transferred to the primary side of the third heat exchanger 20 in step 4. Although it may seem that the necessity of flowing the heat medium is low, in the present embodiment, the heat medium is flown to the primary side of the third heat exchanger 20 in Step 4.
The reason for this is that there may be cases where the main valve of the heating terminal is closed or the heating terminal itself is not connected, and in such a situation, the heat medium is supplied to the second heat exchanger 10 side. Is not flowing. Therefore, in the present embodiment, the bath heat valve 21 is opened in Step 4 to flow the heat medium to the primary side of the third heat exchanger 20, and the first and second heat exchangers are passed through the primary side of the third heat exchanger 20. The heat medium is circulated through the heat exchangers 8 and 10. That is, when the bath heat valve 21 is opened in step 4, a flow path connecting the first and second heat exchangers 8, 10 and the third heat exchanger 20 in an annular shape is opened, and the first and second heat exchangers are opened. Heat medium flows.
[0038]
Then, in step 5, the burner (combustion means) 6 is ignited. Then, in step 6, the control waits until the high temperature side temperature sensor 40 indicates 20 ° C. or more.
When it is confirmed in step 6 that the temperature of the high temperature side sensor 40 has become equal to or higher than 20 ° C., the process proceeds to step 7 to end the heating combustion and close the bath heat valve 21.
The reason why the bath heat valve 21 is closed is to prevent the heat of the heat medium from escaping to the bath side.
That is, when the bath heat valve 21 is opened and the bath water circulation pump 22 is started, heat is exchanged in the third heat exchanger 20, and the heat of the heat medium escapes to the bath side. As a result, the temperature of the heat medium drops rapidly, resulting in frequent combustion (heating combustion) for preventing the above-mentioned freezing. Then, in this embodiment, in order to prevent such a situation, when the heating combustion is completed, the bath heat operated valve 21 is closed.
[0039]
Then, the process proceeds to step 8, and waits for 5 minutes. When 5 minutes have passed and the heat medium has spread throughout the device and the temperature inside the device has increased, the process proceeds to step 9 and the terminal thermal valve is closed. After the heating circulation pump 23 is post-circulated, the heating circulation pump 23 is stopped, and the process returns to step 1.
[0040]
【The invention's effect】
As described above, in the combustion device of the present invention, since the second heat exchanger for recovering latent heat is provided, the thermal efficiency is high. Further, in the combustion device of the present invention, when the combustion means burns during the antifreezing operation, the on-off valve opens, and the flow path to the third heat exchanger is short-circuited to the first and second heat exchangers. open. As a result, water and the like in the first and second heat exchangers circulate through the third heat exchanger. Therefore, in the combustion device of the present invention, the second heat exchanger is prevented from being heated in the water stop state during the antifreezing operation.
Further, in the combustion device of the present invention, since the on-off valve is closed when the combustion is completed, the heat of the heat medium does not escape to the bath side, and wasteful heat dissipation can be prevented.
[0041]
Further, in the combustion device according to the second aspect, the third heat exchanger can reheat the hot water in the bathtub.
[0042]
Further, in the combustion device according to the third aspect, the indoor temperature can be kept at an appropriate temperature by the third heat exchanger.
[Brief description of the drawings]
FIG. 1 is a piping diagram of a combustion device according to an embodiment.
FIG. 2 is a simplified piping system diagram in which essential parts of the piping system diagram of FIG. 1 are extracted.
FIG. 3 is a flowchart illustrating the operation of the combustion device of the present invention.
[Explanation of symbols]
2 can body 3 heating section 8 first heat exchanger 10 second heat exchanger 20 third heat exchanger 21 bath heat valve 22 bath water circulation pump 23 heating circulation pump 24 expansion tank 25 bypass heat valve 26 bypass flow path

Claims

A combustion means for burning fuel, a first heat exchanger for exchanging heat with combustion gas generated in the combustion means, and a first heat exchanger disposed downstream of the first heat exchanger for the combustion gas and passing through the first heat exchanger A second heat exchanger for exchanging heat with the combustion gas, a third heat exchanger located outside the flow path of the combustion gas, a pump, and an on-off valve connected to the third heat exchanger. The first and second heat exchangers are connected in series, and the third heat exchanger is connected by piping so as to connect both ends of the first and second heat exchangers in a state of being connected in series. A pipe is connected between the first heat exchanger and the third heat exchanger and between the second heat exchanger and the first heat exchanger, and an outlet and a return are provided at predetermined positions. And the liquid flows to and from other equipment, and is equipped with an anti-freezing operation function. And the combustion means burns, the on-off valve opens to open a flow path connecting the first and second heat exchangers and the third heat exchanger in an annular shape, and the on-off valve closes when the combustion is completed. apparatus.

The combustion apparatus according to claim 1, wherein the third heat exchanger is a liquid / liquid heat exchanger that heats water in a bathtub.

The combustion device according to claim 1, wherein the first and second heat exchangers are connected to a heating device.