JP3992420B2

JP3992420B2 - Heat exchange device and hot water supply device

Info

Publication number: JP3992420B2
Application number: JP2000122746A
Authority: JP
Inventors: 達範原; 哲司森田; 浩市川; 易司佐野; 直輝石井
Original assignee: Takagi Industrial Co Ltd; Osaka Gas Co Ltd
Current assignee: Takagi Industrial Co Ltd; Osaka Gas Co Ltd
Priority date: 2000-04-24
Filing date: 2000-04-24
Publication date: 2007-10-17
Anticipated expiration: 2020-04-24
Also published as: JP2001304687A

Description

【０００１】
【発明の属する技術分野】
本発明は、燃焼排気から熱を吸収して水等の被加熱流体を加熱する熱交換装置及び給湯装置に関する。
【０００２】
【従来の技術】
メタン、プロパン、ブタン等の燃料を燃焼させ、その燃焼排気から熱を吸収する熱交換器には、複数の熱交換器を併設することにより、顕熱又は潜熱又は双方を回収するために機能分担させたものがある。即ち、熱交換器として燃焼排気から顕熱を回収する顕熱回収用熱交換器を設置し、この顕熱回収用熱交換器側を通過させた燃焼排気から潜熱を回収する潜熱回収用熱交換器を備えるものがそれである。このような熱交換器を設置することにより、給水を潜熱回収用熱交換器側で加熱し、それを顕熱回収用熱交換器で再加熱すれば、熱交換の効率化を図ることができる。
【０００３】
このような熱交換器では９０％以上の熱交換効率を達成することができるが、潜熱回収用熱交換器にはその外表面に燃焼排気中の水蒸気が結露し、窒素酸化物によって強酸性の液体を生じることがある。このため、潜熱回収用熱交換器は強酸性の液体に耐え得る材質で構成することが必要であり、また、強酸性の液体を回収して中和することが必要となる。
【０００４】
また、潜熱回収用熱交換器側で潜熱を回収するには燃焼排気中に含まれる水蒸気を結露する程度まで降温させる必要がある。そこで、顕熱回収用熱交換器には銅等の熱伝導性の高い材質を使用するとともに、吸熱のためフィンを多数配置する等して熱交換効率を高め、燃焼排気から十分に吸熱する必要がある。このように構成した場合、顕熱回収用熱交換器の熱交換効率が８０％程度を越えると、顕熱回収用熱交換器では顕熱と潜熱の両者を回収し始め、潜熱回収によって顕熱回収用熱交換器の表面に結露が生じ、これが腐食の原因になる。このような不都合を防止する技術として特開平１１−１４８７２０号「熱交換器」がある。この熱交換器は、排気経路の上流側に顕熱回収用熱交換器を設け、その下流側に潜熱回収用熱交換器を設置し、顕熱回収用熱交換器の熱交換効率を結露しない範囲、即ち、その実施例によれば、８０％程度の熱交換効率を越えない範囲としたものである。
【０００５】
【発明が解決しようとする課題】
ところで、顕熱回収用熱交換器側の熱交換効率を８０％程度に抑制しても、そのフィン形状、出湯温度、外気温の変化、燃焼量の変動、ガス種による燃焼量の相違によっては露点温度以下に低下して結露を生じるおそれがあり、結露を防止できない。また、顕熱回収用熱交換器と潜熱回収用熱交換器を直列化した場合、その分だけ流体抵抗が増加して流量が減少し、例えば、給湯装置では出湯量を低下させる原因になる。
【０００６】
そこで、本発明は、燃焼排気から顕熱及び潜熱を回収して熱交換効率を向上させ、結露の抑制を実現した熱交換装置及び給湯装置を提供することを課題とする。
【０００７】
【課題を解決するための手段】
本発明は、燃焼手段（バーナ６）で発生した燃焼排気（ＥＧ）中に第１及び第２の熱交換器（２０、２２）を設置し、第１の熱交換器を通して被加熱流体（給水Ｗ）に燃焼排気から主として顕熱を吸収させるとともに、第２の熱交換器を通して被加熱流体に燃焼排気から主として潜熱を吸収させ、第１の熱交換器の受熱管（水管２４）又は第１及び第２の熱交換器の受熱管（水管２４、２８）に並列にバイパス管路（５４、５５）を設置し、このバイパス管路に流す被加熱流体によって第１の熱交換器側の被加熱流体の流量を制御し、第１の熱交換器側で凝縮水によって生じる結露を抑制し、腐食、腐食による強度の低下や損傷の発生防止、熱交換効率の有効活用により燃料消費量の低減を図っている。
【０００８】
また、請求項１に係る本発明の熱交換装置は、燃料を燃焼させて燃焼排気（ＥＧ）を排気通路（８）に流す燃焼手段（バーナ６）と、前記排気通路の上流側に設置されて受熱管（水管２４）に流れる被加熱流体（給水Ｗ）に前記燃焼排気から主として顕熱を吸収させる第１の熱交換器（２０）と、この第１の熱交換器の前記受熱管に直列に接続されるとともに、前記排気通路の下流側に設置された受熱管（水管２８）に流れる前記被加熱流体に、前記第１の熱交換器を通過した前記燃焼排気から主として潜熱を吸収させる第２の熱交換器（２２）と、前記第２の熱交換器の前記受熱管を通過した加熱後の前記被加熱流体を前記第１の熱交換器の前記受熱管に流す管路（４０）と、前記第１の熱交換器の前記受熱管を通過した加熱後の前記被加熱流体を流す管路（４２）との間に接続され、前記第２の熱交換器の前記受熱管を通過した前記被加熱流体の一部を、前記第１の熱交換器の前記受熱管を通過した加熱後の前記被加熱流体に混合させるバイパス管路（５４）と、このバイパス管路に設置されて前記被加熱流体の流量を調整する可変オリフィス（５６）、前記第１の熱交換器の前記受熱管を通過した前記被加熱流体と前記バイパス管路を通過させた前記被加熱流体とを混合して出湯させる混合管路（５７）と、この混合管路に設置されて出湯量を制御する水量制御弁（５０）とを備え、前記第２の熱交換器の前記受熱管を複数の並列化した管路（３０、３２、３４）により構成し、前記第２の熱交換器の前記受熱管の管路断面を前記第２の熱交換器の前後に接続される前記管路より増大させ、前記水量制御弁で制御される前記出湯量に応じて前記可変オリフィスの開度を調整し、前記第１の熱交換器の前記受熱管に流れる前記被加熱流体の流量を制御することを特徴とする。
【０００９】
即ち、燃料の燃焼によって生じた燃焼排気は排気通路の上流側から下流側に流れる。排気通路の上流側の第１の熱交換器の受熱管に流れる被加熱流体は燃焼排気から主として顕熱を吸収し、下流側の第２の熱交換器の受熱管に流れる被加熱流体は主として潜熱を吸収する。この場合、第２の熱交換器の受熱管に流れる被加熱流体が顕熱を吸収することはあり得るが、第２の熱交換器側で主として潜熱の吸収により加熱された被加熱流体が第１の熱交換器の受熱管に流れて顕熱の吸収により高温に加熱される。また、前記第２の熱交換器の受熱管を複数の管路を並列化して管路断面積を拡大させたので、流体抵抗を低下させることができる。その結果、所望の流量、流水速度を確保して熱交換効率を高め、燃料消費量の抑制に寄与する。
【００１０】
また、第２の熱交換器の出口側で分流させた被加熱流体は、バイパス管路を通じて第１の熱交換器の出口側の被加熱流体に合流する。即ち、第２の熱交換器側の低温の被加熱流体は、それを第１の熱交換器で加熱したその出口側の高温の被加熱流体と混合されるので、被加熱流体の全流量を以て第１の熱交換器の受熱管側の被加熱流体の流量とバイパス管路側の流量との比率を任意に調整できる。したがって、第１の熱交換器側の被加熱流体の加熱温度を露点温度以上に高めることができ、第１の熱交換器側の凝縮水による結露を防止できる。
【００１１】
また、請求項２に係る本発明の熱交換装置は、燃料を燃焼させて燃焼排気（ＥＧ）を排気通路（８）に流す燃焼手段（バーナ６）と、前記排気通路の上流側に設置されて受熱管（水管２４）に流れる被加熱流体に前記燃焼排気から主として顕熱を吸収させる第１の熱交換器（２０）と、この第１の熱交換器の前記受熱管に直列に接続されるとともに、前記排気通路の下流側に設置された受熱管（水管２８）に流れる前記被加熱流体に、前記第１の熱交換器を通過した前記燃焼排気から主として潜熱を吸収させる第２の熱交換器（２２）と、前記第２の熱交換器の前記受熱管に加熱前の前記被加熱流体を流す管路（３８）と前記第１の熱交換器の前記受熱管を通過した加熱後の前記被加熱流体を流す管路（４２）との間に接続され、前記第２の熱交換器の前記受熱管の通過前の前記被加熱流体の一部を前記第１の熱交換器の前記受熱管を通過した前記被加熱流体に混合させるバイパス管路（５５）と、このバイパス管路に設置されて前記被加熱流体の流量を調整する可変オリフィス（５６）と、前記第１の熱交換器の前記受熱管を通過した前記被加熱流体と前記バイパス管路を通過させた前記被加熱流体とを混合して出湯させる混合管路（５７）と、この混合管路に設置されて出湯量を制御する水量制御弁（５０）とを備え、前記第２の熱交換器の前記受熱管を複数の並列化した管路（３０、３２、３４）により構成し、前記第２の熱交換器の前記受熱管の管路断面を前記第２の熱交換器の前後に接続される前記管路より増大させ、前記水量制御弁で制御される前記出湯量に応じて前記可変オリフィスの開度を調整し、前記第１の熱交換器の前記受熱管に流れる前記被加熱流体の流量を制御することを特徴とする。
【００１２】
即ち、この場合も同様に、第２の熱交換器側で潜熱の吸収により加熱された被加熱流体は、第１の熱交換器の受熱管に流れて顕熱の吸収により高温に加熱される。また、前記第２の熱交換器の受熱管を複数の管路を並列化して管路断面積を拡大させたので、流体抵抗を低下させることができる。その結果、所望の流量、流水速度を確保して熱交換効率を高め、燃料消費量の抑制に寄与する。
【００１３】
そして、第２の熱交換器の入口側で分流させた被加熱流体は、バイパス管路を通じては第１の熱交換器の出口側の被加熱流体に合流する。即ち、加熱されていない被加熱流体は分流され、その一部が第２の熱交換器及び第１の熱交換器で加熱され、その出口側の高温の被加熱流体に他の一部が混合されるので、被加熱流体の全流量を以て第１の熱交換器の受熱管側の被加熱流体の流量とバイパス管路側の流量との比率を任意に調整できる。したがって、第１の熱交換器側の被加熱流体の加熱温度を露点温度以上に高めることができ、第１の熱交換器側の凝縮水による結露を防止できる。
【００１４】
また、請求項３に係る本発明の熱交換装置は、前記第１の熱交換器（２０）側の前記受熱管（水管２４）を流れる前記被加熱流体の温度を検出する温度検出手段（温度センサ４８）を備え、前記被加熱流体の温度に応じて前記可変オリフィスの開度を調整して前記被加熱流体の流量を制御し、前記第１の熱交換器を露点温度以上に加熱することを特徴とする。
【００１５】
即ち、第１の熱交換器側の受熱管の被加熱流体の温度を検出し、この検出温度に基づき第１の熱交換器の受熱管又は第１及び第２の熱交換器の受熱管の流量調整を行う。この結果、第１の熱交換器の受熱管側の温度低下を防止でき、第１の熱交換器側の結露を防止できる。
【００１６】
また、請求項４に係る本発明の熱交換装置は、前記被加熱流体の設定温度により前記燃焼手段の燃焼量を制御手段（制御装置７０）によって制御することを特徴とする。即ち、制御手段により燃焼手段の燃焼量を制御することにより、第１の熱交換器側の加熱温度を制御することができる。
【００１７】
また、請求項５に係る本発明の熱交換装置は、前記第１の熱交換器の前記受熱管（水管２４）の吸熱フィン（２６）の突出長（Ｌ）又は厚さによって吸熱量を調整したことを特徴とする。即ち、吸熱フィンの突出長又は厚さにより、その吸熱量を調整でき、第１の熱交換器の受熱管の吸熱フィンの低温化を防止できる。
【００１８】
また、請求項６に係る本発明の熱交換装置は、前記第２の熱交換器の外壁部材を耐酸性素材で構成し、かつ、前記第２の熱交換器の外表面に生じた凝縮水（５８）を回収する手段（回収ホッパ６０）を備え、回収した前記凝縮水を中和させることを特徴とする。即ち、第２の熱交換器の外壁部材をチタン、ステンレス鋼等の耐酸性素材で構成することにより、酸性の凝縮水による腐食、腐食による機械的強度の低下や損傷の発生を防止できる。その凝縮水は、回収して中和することにより無害化でき、自由に廃棄することができる。
【００１９】
また、請求項７に係る本発明の熱交換装置は、前記第１の熱交換器の受熱管を複数の管路で構成し、前記第１の熱交換器の前記受熱管の管路断面を前記第１の熱交換器の前後に接続される前記管路より増大させたことを特徴とする。即ち、受熱管を屈曲形成すれば、燃焼排気から潜熱又は顕熱を効率的に回収することができるが、その分だけ流体抵抗が増大する。そこで、この受熱管を複数の管路を並列化して管路断面積を拡大すれば、流体抵抗を低下させることができる。その結果、所望の流量、流水速度を確保して熱交換効率を高め、燃料消費量の抑制に寄与することができる。
【００２０】
そして、請求項８に係る本発明の給湯装置は、前記熱交換装置を用いて給水を加熱し、給湯することを特徴とする。即ち、被加熱流体を給水とすれば、その給水を効率的に加熱して給湯することができる。
【００２１】
【発明の実施の形態】
図１には本発明の熱交換装置及びそれを用いた給湯装置の実施形態が示されている。この熱交換装置及び給湯装置のハウジング２には胴部３が設置され、この胴部３の内部に燃焼室４が形成されている。この燃焼室４には燃焼手段であるバーナ６が設置され、このバーナ６の下側には給気部として燃焼空気を取り込む給気ファン７が設けられ、燃焼室４の上部及び側部側に胴部３を延長する形態で排気通路８が形成され、この排気通路８は排気口１０に開口されている。バーナ６にはガス供給管１２を通じて燃料ガスＧが供給されており、このガス供給管１２には燃料ガスＧの供給又は遮断を切り換える燃料開閉弁１４、燃料ガスＧの供給を制御する燃料比例弁１６が設けられ、また、バーナ６には隣接して着火手段である放電器１８が設置されている。したがって、給気ファン７からの給気Ｅと燃焼ガスＧとを以てバーナ６の燃焼により発生した燃焼排気ＥＧは、排気通路８を経てハウジング２の排気口１０から外気に放出される。
【００２２】
そして、燃焼室４の上部側、即ち、排気通路８の上流側には第１の熱交換器２０、その下流側には第２の熱交換器２２が設置されている。熱交換器２０は、受熱管として水管２４を燃焼室４の外壁に巻き付けて設置され、その水管２４の周囲には複数の吸熱フィン２６が形成されている。また、熱交換器２２は、排気通路８内に屈曲した受熱管としての水管２８を設置したものであり、この実施形態では、複数の管路３０、３２、３４の併設によって管路断面積を拡大した水管２８が構成され、その周囲に無数の吸熱フィン３６が設けられている。また、管路３０、３２、３４をフレキシブルパイプ等の波状の管体にして吸熱効率を向上させても良い。熱交換器２２の水管２８及び吸熱フィン３６は、ステンレスやチタン等の耐酸性素材で形成されている。即ち、燃焼排気ＥＧの上流側に設置されている熱交換器２０には水管２４を流れる被加熱流体として例えば、給水Ｗに燃焼排気ＥＧから主として顕熱を吸収させ、燃焼排気ＥＧの下流側に設置されている熱交換器２２には水管２８を流れる給水Ｗに燃焼排気ＥＧから主として潜熱を吸収させる。
【００２３】
また、熱交換器２２の水管２８の入口側には、上水等の給水Ｗを受けるための管路３８が連結され、水管２８の出口側と熱交換器２０の水管２４の入口側との間は管路４０を通じて連結され、また、熱交換器２０の出口側には出湯用の管路４２が接続されている。管路３８には給水温度を検出する温度センサ４４が設けられ、管路４０には水量センサ４６が設けられ、管路４２には熱交換器２０の出口側の温度を検出する温度センサ４８が設けられている。そして、管路４０と管路４２との間には、水管２４と並列にバイパス管路５４が設けられ、このバイパス管路５４には通過水量を調整する可変オリフィス５６が設けられている。そして、バイパス管路５４からの温水と管路４２からの温水は混合管路５７で合流し、この混合管路５７には水量制御弁５０及び温度センサ５２が設けられている。
【００２４】
また、熱交換器２２の水管２８の下側には凝縮水５８を受ける回収手段としての回収ホッパ６０が設けられ、この回収ホッパ６０に回収された凝縮水５８は、管路６２を通じて中和器６４に導かれる。この中和器６４には酸性の凝縮水５８を中和するため、アルカリ性等の中和剤６６が充填されている。中和された凝縮水５８は、管路６８を通して外部に排出される。
【００２５】
次に、図２は、給湯制御部の実施の形態を示している。この給湯制御部にはマイクロコンピュータ等で構成された制御手段として制御装置７０が設置され、この制御装置７０は演算手段としてのＣＰＵ、記憶手段としてのＲＯＭ及びＲＡＭ等を備えており、ＲＯＭには給湯制御等のプログラム、ＲＡＭには検出データ等がそれぞれ格納される。
【００２６】
制御装置７０には温度設定器７２から設定温度が加えられるとともに、各種の温度センサ４４、４８、５２、水量センサ４６等の検出出力が取り込まれ、制御出力が燃料開閉弁１４、燃料比例弁１６、可変オリフィス５６、水量制御弁５０、給気ファン７のファンモータ７４等に加えられる。
【００２７】
次に、動作を説明すると、図３に示すように、バーナ６で燃料ガスＧを燃焼させると、燃焼排気ＥＧが発生する。この燃焼排気ＥＧが持つ熱量をＨ₀、熱交換器２０側の交換熱量をＨ₁、水温上昇をΔｔ₁、熱交換器２２側の交換熱量をＨ₂、水温上昇をΔｔ₂とすると、燃焼排気ＥＧの熱量Ｈ₀から熱交換器２０側で熱量Ｈ₁が吸収されて熱交換器２２側には熱量（Ｈ₀−Ｈ₁）の燃焼排気ＥＧが流れ、熱交換器２２を通過した燃焼排気ＥＧの熱量は（Ｈ₀−Ｈ₁−Ｈ₂）となる。
【００２８】
そこで、バイパス管路５４側を閉鎖した状態を想定し、熱交換器２２に水温ｔ₀の給水Ｗを行うと、熱交換器２２の出口側、即ち、熱交換器２０の入口側の水温ｔ₁は（ｔ₀＋Δｔ₂）に昇温され、この温水は熱交換器２０側に流れ、出湯温度ｔ₂は、（ｔ₀＋Δｔ₂＋Δｔ₁）となる。
【００２９】
この場合、バーナ６で得られた燃焼排気ＥＧの温度を１５００℃とすると、熱交換器２０を通過した燃焼排気ＥＧの温度は２００℃に低下し、さらに熱交換器２２を通過した燃焼排気ＥＧの温度は８０℃に低下することとなる。
【００３０】
このとき、熱量Ｈ₀に対する交換熱量Ｈ₁の比率（Ｈ₁／Ｈ₀）は、Ｈ₁／Ｈ₀＝８０％、熱量Ｈ₀に対する交換熱量Ｈ₂の比率（Ｈ₂／Ｈ₀）は、Ｈ₂／Ｈ₀＝１０％、（Ｈ₁＋Ｈ₂）／Ｈ₀＝９０％であり、Δｔ₂：Δｔ₁＝１０：８０、Ｈ₁：Ｈ₂＝Δｔ₁：Δｔ₂である。
【００３１】
そして、図４の（ａ）に示すように燃焼排気中の顕熱は熱交換効率９０％まで回収でき、潜熱は熱交換効率が９０％を越えるとき、回収される。そこで、図４の（ｂ）に示すように熱交換効率９０％の熱交換器を熱交換器２０に用いた場合、理論的には顕熱の総てを回収できる筈であるが、実際には、顕熱の８５％、潜熱の５％程度が回収され、その際、熱交換器２０は流水の吸熱により、その一部が露点温度（４０〜５０℃）以下に低下する。この結果、熱交換器２０の表面には凝縮水が生じ、この凝縮水は酸性であるため腐食を生じさせる。このため、図４の（ｃ）に示すように、熱交換器２０側で顕熱のみを回収できる最大の熱交換効率（例えば最大燃焼時において８０％の熱交換効率）を設定し、残りの熱量を耐酸性素材で形成された熱交換器２２で吸収させて高効率化を実現している。
【００３２】
ところで、熱交換器２０を通過した燃焼排気の温度は約２００℃程度に低下するため、熱交換器２０の水管２４の吸熱フィン２６の一部等が低温化、即ち、４０℃〜５０℃以下の露点温度に冷却されて凝縮水を生じさせるおそれがある。これは給水温度ｔ₀によっても発生する。このような露点温度以下の低温化を防止するには、水管２４を通過する温水の温度を上昇させて吸熱フィン２６の温度を露点温度以上に昇温させることが必要となる。熱交換器２０側の対策として、吸熱フィン２６から水管２４への吸熱量を調整し、吸熱フィン２６の熱交換面が露点温度より高くなるようにする。即ち、図５に示すように、吸熱フィン２６の吸熱量は吸熱フィン２６と水管２４との距離Ｌや吸熱フィン２６の厚みを調整して実現することができる。この結果、熱交換器２０の排気側、即ち、下流側の結露防止をある程度図ることができる。この場合、給水Ｗは、上流側の熱量Ｈ₀を受けて加熱されると、その水温ｔ₀は水管２４の下側で（ｔ₀＋Δｔ_1a）に上昇し、その上昇温度Δｔ_1aは熱量Ｈ_1aに対応する。このため、水管２４の上側、即ち、下流側で熱量（Ｈ₀−Ｈ_1a）を受け、熱交換器２０から水温（ｔ₀＋Δｔ₁）の湯が得られる。
【００３３】
そして、バイパス管路５４の通過水量によって吸熱フィン２６の温度を露点温度以上に昇温させるには、熱交換器２０の出口側の温水温度を温度センサ４８で検出し、その検出温度に応じて可変オリフィス５６の開度を調整することにより、バイパス管路５４側と熱交換器２０側に流れる水量の比率を変更する。即ち、バイパス管路５４側の水量を少なくし、熱交換器２０側の水量を増加させて水管２４側の温水温度を上昇させることができ、熱交換器２０側が露点温度以下に低温化することを防止でき、熱交換器２０側の結露を防止できる。
【００３４】
この場合、バイパス管路５４側の水量と熱交換器２０側の水量の比を１：１とすると、熱交換器２２の水管２８を通過した給水Ｗは熱量Ｈ₂を吸収し、給水ＷをΔｔ₂だけ昇温させることができる。図６は、この場合の等価回路を示しており、この温水はバイパス管路５４と熱交換器２０側とに例えば、１：１で分流され、熱交換器２０側で熱量Ｈ₁が吸収され、温水は更にΔｔ₁だけ昇温する。この場合、バイパス管路５４側の温水の温度ｔａは、
ｔａ＝（ｔ₀＋Δｔ₂）・・・（１）
であり、熱交換器２０側の温水の温度ｔｂは、
ｔｂ＝（ｔ₀＋Δｔ₂＋Δｔ₁）・・・（２）
である。
【００３５】
混合比率は１：１であるから、混合管路５７の出湯温度ｔｃは、

である。ここで、バイパス管路５４が無い場合、又は可変オリフィス５６を閉じている場合には、混合管路５７の出湯温度ｔｄは、
ｔｄ＝ｔ₀＋Δｔ₂＋Δｔ_1b ・・・（４）
となる。
【００３６】
ここで、出湯温度ｔｃ、ｔｄを同一と仮定すれば、バイパス管路５４のない場合には、熱交換器２０側の水量がバイパス管路５４のある場合の２倍となるため、Δｔ₁：Δｔ_1b＝２：１の関係から、
Δｔ_1b＝Δｔ₁／２・・・（５）
となる。この結果、バイパス管路５４を通じて温水を分流させて混合管路５７で合流させる場合には、熱交換器２０の水管２４の温水温度を高くでき、熱交換器２０側の結露を防止することができる。
【００３７】
また、熱交換器２０を通過する水量を多くすることによる熱交換効率の増加も期待でき、熱回収効率が高く、燃料の消費量を低減することができる。
【００３８】
ところで、この熱交換装置及び給湯装置において、バイパス管路５４と熱交換器２０の熱回収率との関係、即ち、バイパス管路５４による分流の熱交換器２０の熱回収率への影響について見ると、熱交換器２０は上述のように、１５００℃程度に加熱され、一方、水温は数十℃であるため、バイパス管路５４が無いとき、熱交換器２０の熱交換量が大きくなるが、熱交換器２０の加熱温度１５００℃から見れば、無視できる程度の温度差であり、バイパス管路５４による分流が熱交換器２０の熱吸収率に影響することはない。
【００３９】
また、バイパス管路５４と熱交換器２０の熱交換効率との関係、即ち、バイパス管路５４による分流が熱交換器２０の熱交換効率への影響について見ると、バイパス管路５４を設けて分流することは、熱交換器２０による加熱前と加熱後で温度差が若干縮まること、その結果、熱交換器２０の水管２４の管内流速の低下による管内伝熱係数の減少により、熱交換器２０の熱交換効率が僅かに低下する。しかしながら、バイパス管路５４が無い場合、熱交換器２０の熱交換率が８０％、バイパス管路５４を付けた場合、熱交換器２０の熱交換率が７８〜７９％程度の犠牲であるから、バイパス管路５４の設置による結露防止が遙に有利となる。
【００４０】
また、出湯量と加熱温度との関係について見ると、出湯量を同一にして熱交換器２０の水量を抑えた場合、即ち、総流量を変えずに熱交換器２０側とバイパス管路５４側との分配比を変化させ、熱交換器２０の水量を少なくすれば、熱交換器２０の熱交換効率がその流量に応じて低下し、熱交換器２０の加熱温度が上昇することになる。また、出湯量を同一にして熱交換器２０側の水量を多くした場合、熱交換器２０側の加熱温度は低下することになる。
【００４１】
また、熱交換器２０側の吸熱フィン２６の突出長Ｌや厚さにより、熱交換器２０自体の熱交換効率や熱回収率を調整することができるが、吸熱フィン２６の温度には適正な範囲があり、例えば、露点温度以上酸化温度（２５０℃）以下が好ましく、この範囲を越えて高い場合も低い場合も不都合である。また、吸熱フィン２６の厚さについては、その材質に銅を用いた場合、伝熱的な要素よりも耐久的な要素の方が強く、伝熱面積を多く取る場合には、吸熱フィン２６の増加、そのピッチの減少が必要である。
【００４２】
ところで、熱交換器２０、２２は直列に接続されており、水管２４側の流体抵抗をＲ₁、水管２８側の各流体抵抗をＲ₂とすると、通水経路は図７に示す等価回路で表すことができる。水管２８側の管路３０〜３４の並列数をｎとすると、全通水抵抗Ｒは、
Ｒ＝Ｒ₁＋Ｒ₂／ｎ・・・（６）
となり、水管２８側の管路３０〜３４の並列化により全通水抵抗Ｒの大幅な低減が図られる。したがって、給湯装置では安定した出湯量を得ることができる。
【００４３】
そして、混合管路５７から得られる出湯量は、水量制御弁５０によって制御することができ、その出湯量に応じて可変オリフィス５６の開度を調整し、熱交換器２０側の流量を制御することができる。熱交換器２０側の流量を多く設定すれば、熱交換器２０の水管２４の温水温度を高くでき、熱交換器２０側の結露を防止することができる。
【００４４】
また、混合管路５７から得られる出湯温度は温度センサ５２によって検出され、その検出温度によってバーナ６の燃焼量を加減することにより設定温度の出湯が可能である。そして、この場合も、設定温度に応じて熱交換器２０側の流量を制御することが可能であり、熱交換器２０の水管２４の温水温度を高くすることで、熱交換器２０側の結露を防止することができる。
【００４５】
次に、図８に示す本発明の他の実施の形態について説明すると、管路３８と熱交換器２０の出口側の管路４２との間にバイパス管路５５を設置し、給水Ｗを熱交換器２２の入口側で例えば、１：１の比率で分流させ、その給水Ｗを熱交換器２０の出口側の温水に混合してもよい。図９は、この場合の等価回路を示しており、バイパス管路５５側の給水の温度はｔ₀であり、熱交換器２０、２２で加熱された温水の温度ｔｅは、
ｔｅ＝ｔ₀＋Δｔ₂＋Δｔ₁ ・・・（７）
である。
【００４６】
混合比率は１：１であるから、混合管路５７の出湯温度ｔｆは、

となる。但し、ΔＴ_a＝（Δｔ₂＋Δｔ₁）／２である。ここで、バイパス管路５５が無い場合又は可変オリフィス５６を閉じて出湯温度ｔｇを得る場合は式（４）に示した出湯温度ｔｄと同様であり、

となる。但し、ΔＴ_b＝Δｔ₂＋Δｔ_1bである。
【００４７】
ΔＴ_a：ΔＴ_b＝２：１となることから、バイパス管路５５を通じて給水Ｗを分流させ、混合管路５７で合流させることで、熱交換器２０の水管２４の温水の温度を高くすることができる。そして、この場合も、熱交換器２０を通過する水量を多くすることによる熱交換効率の増加も期待でき、熱回収効率が高く、燃料の消費量を低減することができる。
【００４８】
なお、上記実施形態では、給湯装置に適用した熱交換装置を例に取って説明したが、本発明の熱交換装置は、給湯装置以外にも適用でき、例えば、被加熱流体としての熱媒を加熱する暖房装置に適用することもできる。
【００４９】
【発明の効果】
以上説明したように、本発明によれば、次の効果が得られる。
ａ請求項１に係る本発明によれば、第２の熱交換器で加熱した被加熱流体を第１及び第２の熱交換器で加熱した被加熱流体と混合するので、第１の熱交換器側の加熱温度を高くでき、第１の熱交換器側の結露を抑制して凝縮水による第１の熱交換器側の腐食、腐食による強度の低下や損傷の発生を防止でき、熱回収効率の有効活用を図ることができ、燃料の消費量を低減することができる。また、第２の熱交換器の受熱管は複数の管路を並列化して管路断面積を拡大して流体抵抗を低下させたので、所望の流量、流水速度を確保して熱交換効率を高め、燃料消費量の抑制に寄与することができる。
ｂ請求項２に係る本発明によれば、加熱前の被加熱流体と第１及び第２の熱交換器で加熱した被加熱流体とを混合するので、第１の熱交換器側の加熱温度を高くでき、第１の熱交換器側の結露を抑制して凝縮水による第１の熱交換器側の腐食、腐食による強度低下や損傷の発生を防止でき、熱回収効率の有効活用により燃料の消費量を低減させることができる。
ｃ請求項３に係る本発明によれば、第１の熱交換器側の受熱管の被加熱流体の温度を検出し、この検出温度に基づき第１の熱交換器の受熱管又は第１及び第２の熱交換器の受熱管の流量調整を行うので、第１の熱交換器の受熱管側の温度低下を防止でき、第１の熱交換器側の結露を防止できる。
ｄ請求項４に係る本発明によれば、燃焼手段の燃焼量を制御して第１の熱交換器側の加熱温度を制御するので、第１の熱交換器側の加熱温度を高くでき、第１の熱交換器側の結露を抑制することができる。
ｅ請求項５に係る本発明によれば、第１の熱交換器の受熱管の吸熱フィンの突出長又は厚さを以て吸熱量を調整するので、被加熱流体の加熱制御と相まって第１の熱交換器の受熱管の吸熱フィンの低温化を防止でき、結露を抑制できる。
ｆ請求項６に係る本発明によれば、第２の熱交換器の外壁部材をチタン、ステンレス鋼等の耐酸性素材で構成するので、酸性の凝縮水による損傷を防止でき、また、その凝縮水は、回収して中和することにより無害化を達成できる。
ｇ請求項７に係る本発明によれば、複数の管路を並列化して管路断面積を拡大することにより、受熱管の流体抵抗が低下するので、所望の流量、流水速度を確保して熱交換効率を高め、燃料消費量の抑制に寄与することができる。
ｈそして、請求項８に係る本発明によれば、効率的を給湯を行うことができるとともに、凝縮水による損傷を防止でき、高耐久性の給湯装置を提供できる。
【図面の簡単な説明】
【図１】本発明の熱交換装置及び給湯装置の一実施形態を示す配管図である。
【図２】制御部の構成を示すブロック図である。
【図３】バーナの発生熱量、第１及び第２の熱交換器による熱交換を示す図である。
【図４】熱交換器の熱交換及び熱効率を示す図である。
【図５】第１の熱交換器側の結露及びその防止を示す図である。
【図６】バイパス管路による温水混合を示す図である。
【図７】第１及び第２の熱交換器における流体抵抗による等価回路を示す回路図である。
【図８】バイパス管路の他の実施形態を示す配管図である。
【図９】バイパス管路による温水混合を示す図である。
【符号の説明】
６バーナ（燃焼手段）
８排気通路
Ｇ燃料ガス
Ｗ給水
ＥＧ燃焼排気
２０第１の熱交換器
２２第２の熱交換器
２４水管（受熱管）
２６吸熱フィン
２８水管（受熱管）
３０、３２、３４管路
４８温度センサ（温度検出手段）
５４、５５バイパス管路
５６可変オリフィス（流量調整手段）
５８凝縮水
６０回収ホッパ
７０制御装置（制御手段）[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat exchange device and a hot water supply device that absorbs heat from combustion exhaust and heats a fluid to be heated such as water.
[0002]
[Prior art]
A heat exchanger that burns fuel such as methane, propane, and butane and absorbs heat from the combustion exhaust has a function sharing in order to recover sensible heat or latent heat or both by providing multiple heat exchangers. There is something that let me. In other words, a sensible heat recovery heat exchanger that recovers sensible heat from combustion exhaust as a heat exchanger is installed, and latent heat recovery heat exchange that recovers latent heat from the combustion exhaust that has passed through the sensible heat recovery heat exchanger side It is the one with the vessel. By installing such a heat exchanger, if the feed water is heated on the latent heat recovery heat exchanger side and then reheated on the sensible heat recovery heat exchanger, the efficiency of heat exchange can be improved. .
[0003]
In such a heat exchanger, a heat exchange efficiency of 90% or more can be achieved. However, in the heat exchanger for latent heat recovery, water vapor in the combustion exhaust is condensed on the outer surface of the heat exchanger. May produce liquid. For this reason, it is necessary to configure the heat exchanger for recovering latent heat with a material that can withstand a strongly acidic liquid, and it is also necessary to recover and neutralize the strongly acidic liquid.
[0004]
Further, in order to recover latent heat on the latent heat recovery heat exchanger side, it is necessary to lower the temperature to such an extent that water vapor contained in the combustion exhaust is condensed. Therefore, the heat exchanger for sensible heat recovery needs to use a material with high thermal conductivity such as copper and increase heat exchange efficiency by arranging a large number of fins for heat absorption to absorb heat sufficiently from the combustion exhaust. There is. In this configuration, when the heat exchange efficiency of the sensible heat recovery heat exchanger exceeds about 80%, the sensible heat recovery heat exchanger starts to recover both sensible heat and latent heat, and sensible heat is recovered by latent heat recovery. Condensation forms on the surface of the recovery heat exchanger, which causes corrosion. As a technique for preventing such an inconvenience, there is JP-A-11-148720 “Heat Exchanger”. This heat exchanger has a sensible heat recovery heat exchanger on the upstream side of the exhaust path and a latent heat recovery heat exchanger on the downstream side thereof, so that the heat exchange efficiency of the sensible heat recovery heat exchanger is not condensed. The range, that is, the range that does not exceed the heat exchange efficiency of about 80% according to the embodiment.
[0005]
[Problems to be solved by the invention]
By the way, even if the heat exchange efficiency on the sensible heat recovery heat exchanger side is suppressed to about 80%, depending on the fin shape, tapping temperature, change in outside air temperature, fluctuation in combustion amount, and difference in combustion amount depending on gas type Condensation may occur due to a drop below the dew point temperature, and condensation cannot be prevented. In addition, when the sensible heat recovery heat exchanger and the latent heat recovery heat exchanger are serialized, the fluid resistance increases and the flow rate decreases by that amount. For example, in a hot water supply device, the amount of discharged hot water is reduced.
[0006]
Then, this invention makes it a subject to collect | recover sensible heat and latent heat from combustion exhaust, improve heat exchange efficiency, and provide the heat exchange apparatus and hot water supply apparatus which implement | achieved suppression of dew condensation.
[0007]
[Means for Solving the Problems]
In the present invention, the first and second heat exchangers (20, 22) are installed in the combustion exhaust (EG) generated by the combustion means (burner 6), and the heated fluid (feed water) is passed through the first heat exchanger. W) mainly absorbs sensible heat from the combustion exhaust gas and causes the fluid to be heated to absorb mainly latent heat from the combustion exhaust gas through the second heat exchanger, so that the heat receiving pipe (water pipe 24) or the first heat exchanger pipe of the first heat exchanger In addition, bypass pipes (54, 55) are installed in parallel with the heat receiving pipes (water pipes 24, 28) of the second heat exchanger, and the first heat exchanger side is covered by the heated fluid flowing through the bypass pipes. Controls the flow rate of the heating fluid, suppresses condensation caused by condensed water on the first heat exchanger side, reduces the amount of fuel consumed by corrosion, reduces strength due to corrosion, prevents damage, and effectively uses heat exchange efficiency I am trying.
[0008]
  The heat exchanging device of the present invention according to claim 1 is installed on the upstream side of the combustion means (burner 6) for burning the fuel and flowing the combustion exhaust (EG) to the exhaust passage (8), and the exhaust passage. A first heat exchanger (20) that causes the heated fluid (feed water W) flowing through the heat receiving pipe (water pipe 24) to absorb mainly sensible heat from the combustion exhaust, and the heat receiving pipe of the first heat exchanger. The heated fluid that is connected in series and that flows through the heat receiving pipe (water pipe 28) installed on the downstream side of the exhaust passage mainly absorbs latent heat from the combustion exhaust gas that has passed through the first heat exchanger. A second heat exchanger (22);2The heated fluid that has passed through the heat receiving pipe of the heat exchanger1A pipe (40) that flows through the heat receiving pipe of the first heat exchanger and a pipe (42) through which the heated fluid that has passed through the heat receiving pipe of the first heat exchanger flows. And bypassing a part of the heated fluid that has passed through the heat receiving pipe of the second heat exchanger with the heated fluid that has passed through the heat receiving pipe of the first heat exchanger. A conduit (54), a variable orifice (56) installed in the bypass conduit to adjust the flow rate of the heated fluid, the heated fluid that has passed through the heat receiving tube of the first heat exchanger, and the A mixing pipe (57) for mixing and heating out the heated fluid that has passed through the bypass pipe, and a water amount control valve (50) that is installed in the mixing pipe and controls the amount of hot water, A plurality of pipes (30, 32, 34) in which the heat receiving pipes of the second heat exchanger are arranged in parallel The pipe cross section of the heat receiving pipe of the second heat exchanger is larger than the pipe connected to the front and rear of the second heat exchanger, and is controlled by the water amount control valve. The flow rate of the fluid to be heated flowing in the heat receiving pipe of the first heat exchanger is controlled by adjusting the opening of the variable orifice according to the amount of hot water.
[0009]
  That is, the combustion exhaust generated by the combustion of fuel flows from the upstream side to the downstream side of the exhaust passage. The heated fluid flowing in the heat receiving pipe of the first heat exchanger on the upstream side of the exhaust passage mainly absorbs sensible heat from the combustion exhaust, and the heated fluid flowing in the heat receiving pipe of the second heat exchanger on the downstream side is mainly Absorbs latent heat. In this case, the heated fluid flowing in the heat receiving pipe of the second heat exchanger may absorb sensible heat, but the heated fluid heated mainly by the absorption of latent heat on the second heat exchanger side 1 flows into the heat receiving tube of the heat exchanger 1 and is heated to a high temperature by absorbing sensible heat.Further, since the heat receiving pipe of the second heat exchanger has a plurality of pipes arranged in parallel to expand the pipe cross-sectional area, the fluid resistance can be reduced. As a result, a desired flow rate and flowing water speed are ensured to increase heat exchange efficiency and contribute to the suppression of fuel consumption.
[0010]
In addition, the fluid to be heated divided on the outlet side of the second heat exchanger joins the fluid to be heated on the outlet side of the first heat exchanger through the bypass pipe. That is, the low-temperature heated fluid on the second heat exchanger side is mixed with the high-temperature heated fluid on the outlet side heated by the first heat exchanger, so that the total flow rate of the heated fluid is increased. The ratio of the flow rate of the heated fluid on the heat receiving pipe side of the first heat exchanger and the flow rate on the bypass pipe side can be arbitrarily adjusted. Therefore, the heating temperature of the fluid to be heated on the first heat exchanger side can be increased to the dew point temperature or higher, and condensation due to condensed water on the first heat exchanger side can be prevented.
[0011]
  The heat exchanging device of the present invention according to claim 2 is installed on the upstream side of the exhaust passage and the combustion means (burner 6) for burning the fuel and flowing the combustion exhaust (EG) to the exhaust passage (8). A first heat exchanger (20) for absorbing mainly sensible heat from the combustion exhaust to the heated fluid flowing through the heat receiving pipe (water pipe 24), and the heat receiving pipe of the first heat exchanger. And second heat that causes the heated fluid flowing in the heat receiving pipe (water pipe 28) installed downstream of the exhaust passage to mainly absorb latent heat from the combustion exhaust gas that has passed through the first heat exchanger. After heating through the exchanger (22), the conduit (38) for flowing the heated fluid before heating to the heat receiving pipe of the second heat exchanger, and the heat receiving pipe of the first heat exchanger Connected to a pipe line (42) through which the fluid to be heated flows. Bypass line for mixing a portion of the heated fluid before passing through the heat receiving tube exchanger to the heated fluid passing through the heat receiving pipe of the first heat exchanger (55),A variable orifice (56) that is installed in the bypass pipe to adjust the flow rate of the heated fluid, and the heated fluid that has passed through the heat receiving pipe of the first heat exchanger and the bypass pipe are passed through. The second heat exchanger includes a mixing pipe (57) for mixing and heating the fluid to be heated and a water amount control valve (50) installed in the mixing pipe for controlling the amount of hot water. The heat receiving pipe is configured by a plurality of parallel pipe lines (30, 32, 34), and a pipe cross section of the heat receiving pipe of the second heat exchanger is connected before and after the second heat exchanger. The heated fluid flowing through the heat receiving pipe of the first heat exchanger, the opening of the variable orifice being adjusted according to the amount of hot water controlled by the water amount control valve. Control the flow rate ofIt is characterized by that.
[0012]
  That is, in this case as well, the fluid to be heated heated by the absorption of latent heat on the second heat exchanger side flows into the heat receiving pipe of the first heat exchanger and is heated to a high temperature by absorption of sensible heat. .Further, since the heat receiving pipe of the second heat exchanger has a plurality of pipes arranged in parallel to expand the pipe cross-sectional area, the fluid resistance can be reduced. As a result, a desired flow rate and flowing water speed are ensured to increase heat exchange efficiency and contribute to the suppression of fuel consumption.
[0013]
And the to-be-heated fluid shunted on the inlet side of the second heat exchanger joins the to-be-heated fluid on the outlet side of the first heat exchanger through the bypass line. That is, the heated fluid that has not been heated is diverted, part of which is heated by the second heat exchanger and the first heat exchanger, and the other part is mixed with the hot heated fluid on the outlet side. Therefore, the ratio of the flow rate of the heated fluid on the heat receiving pipe side of the first heat exchanger and the flow rate on the bypass line side can be arbitrarily adjusted with the total flow rate of the heated fluid. Therefore, the heating temperature of the fluid to be heated on the first heat exchanger side can be increased to the dew point temperature or higher, and condensation due to condensed water on the first heat exchanger side can be prevented.
[0014]
  Moreover, the heat exchange device of the present invention according to claim 3 is a temperature detection means (temperature) for detecting the temperature of the heated fluid flowing through the heat receiving pipe (water pipe 24) on the first heat exchanger (20) side. Equipped with sensor 48)Oh, beforeDepending on the temperature of the fluid to be heatedAdjust the opening of the variable orificeControl the flow rate of the heated fluidShiThe first heat exchanger is heated to a dew point temperature or higher.
[0015]
That is, the temperature of the fluid to be heated of the heat receiving pipe on the first heat exchanger side is detected, and the heat receiving pipe of the first heat exchanger or the heat receiving pipes of the first and second heat exchangers is detected based on the detected temperature. Adjust the flow rate. As a result, it is possible to prevent a temperature drop on the heat receiving tube side of the first heat exchanger and to prevent condensation on the first heat exchanger side.
[0016]
According to a fourth aspect of the present invention, the heat exchanging device of the present invention is characterized in that the amount of combustion of the combustion means is controlled by the control means (control device 70) according to the set temperature of the heated fluid. That is, the heating temperature on the first heat exchanger side can be controlled by controlling the combustion amount of the combustion means by the control means.
[0017]
Further, the heat exchange device of the present invention according to claim 5 adjusts the amount of heat absorption by the protrusion length (L) or thickness of the heat absorption fin (26) of the heat receiving pipe (water pipe 24) of the first heat exchanger. It is characterized by that. That is, the amount of heat absorption can be adjusted by the protrusion length or thickness of the heat absorption fin, and the temperature reduction of the heat absorption fin of the heat receiving pipe of the first heat exchanger can be prevented.
[0018]
Moreover, the heat exchange apparatus of the present invention according to claim 6 is configured such that the outer wall member of the second heat exchanger is made of an acid-resistant material, and condensed water is generated on the outer surface of the second heat exchanger. A means (recovery hopper 60) for collecting (58) is provided, and the collected condensed water is neutralized. That is, by forming the outer wall member of the second heat exchanger from an acid-resistant material such as titanium or stainless steel, it is possible to prevent corrosion due to acidic condensed water, mechanical strength decrease due to corrosion, and occurrence of damage. The condensed water can be rendered harmless by being recovered and neutralized, and can be disposed of freely.
[0019]
  Moreover, the heat exchanging device of the present invention according to claim 7 comprises a heat receiving pipe of the first heat exchanger as a plurality of pipes,The pipe cross section of the heat receiving pipe of the first heat exchanger is made larger than the pipe connected before and after the first heat exchanger.It is characterized by that. That is, if the heat receiving pipe is bent, latent heat or sensible heat can be efficiently recovered from the combustion exhaust, but the fluid resistance increases accordingly. Therefore, if this heat receiving pipe has a plurality of pipes arranged in parallel to increase the pipe cross-sectional area, the fluid resistance can be reduced. As a result, it is possible to secure a desired flow rate and flowing water speed, increase heat exchange efficiency, and contribute to suppression of fuel consumption.
[0020]
And the hot-water supply apparatus of this invention which concerns on Claim 8 heats feed water using the said heat exchange apparatus, It is characterized by the above-mentioned. That is, if the fluid to be heated is water supply, the water supply can be efficiently heated to supply hot water.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows an embodiment of a heat exchange device of the present invention and a hot water supply device using the same. A body 3 is installed in the housing 2 of the heat exchange device and the hot water supply device, and a combustion chamber 4 is formed inside the body 3. The combustion chamber 4 is provided with a burner 6 as combustion means, and an air supply fan 7 that takes in combustion air as an air supply section is provided below the burner 6. An exhaust passage 8 is formed so as to extend the body portion 3, and the exhaust passage 8 is opened to the exhaust port 10. A fuel gas G is supplied to the burner 6 through a gas supply pipe 12, and a fuel on-off valve 14 for switching the supply or cutoff of the fuel gas G to the gas supply pipe 12 and a fuel proportional valve for controlling the supply of the fuel gas G. 16 is provided, and the burner 6 is provided with a discharger 18 as an ignition means adjacent thereto. Therefore, the combustion exhaust EG generated by the combustion of the burner 6 by the supply air E and the combustion gas G from the air supply fan 7 is discharged from the exhaust port 10 of the housing 2 to the outside air through the exhaust passage 8.
[0022]
A first heat exchanger 20 is installed on the upper side of the combustion chamber 4, that is, upstream of the exhaust passage 8, and a second heat exchanger 22 is installed on the downstream side thereof. The heat exchanger 20 is installed with a water pipe 24 wound around the outer wall of the combustion chamber 4 as a heat receiving pipe, and a plurality of heat absorbing fins 26 are formed around the water pipe 24. In addition, the heat exchanger 22 is provided with a water pipe 28 as a heat receiving pipe bent in the exhaust passage 8. In this embodiment, the pipe cross-sectional area is increased by providing a plurality of

pipes

30, 32, 34. An enlarged water pipe 28 is formed, and an infinite number of heat absorbing fins 36 are provided around the water pipe 28. In addition, the heat absorption efficiency may be improved by making the

conduits

30, 32, and 34 into wavy tubular bodies such as flexible pipes. The water tubes 28 and the heat absorption fins 36 of the heat exchanger 22 are formed of an acid resistant material such as stainless steel or titanium. That is, in the heat exchanger 20 installed on the upstream side of the combustion exhaust EG, as the fluid to be heated flowing in the water pipe 24, for example, the feed water W mainly absorbs sensible heat from the combustion exhaust EG, and on the downstream side of the combustion exhaust EG. The installed heat exchanger 22 causes the feed water W flowing through the water pipe 28 to mainly absorb latent heat from the combustion exhaust EG.
[0023]
Further, a pipe line 38 for receiving water supply W such as clean water is connected to the inlet side of the water pipe 28 of the heat exchanger 22, and the outlet side of the water pipe 28 and the inlet side of the water pipe 24 of the heat exchanger 20 are connected. The space is connected through a conduit 40, and a hot water discharge conduit 42 is connected to the outlet side of the heat exchanger 20. The pipe 38 is provided with a temperature sensor 44 that detects the feed water temperature, the pipe 40 is provided with a water amount sensor 46, and the pipe 42 is provided with a temperature sensor 48 that detects the temperature on the outlet side of the heat exchanger 20. Is provided. A bypass pipe 54 is provided between the pipe 40 and the pipe 42 in parallel with the water pipe 24, and a variable orifice 56 for adjusting the amount of passing water is provided in the bypass pipe 54. The warm water from the bypass line 54 and the warm water from the line 42 are merged in a mixing line 57, and a water amount control valve 50 and a temperature sensor 52 are provided in the mixing line 57.
[0024]
A recovery hopper 60 as a recovery means for receiving the condensed water 58 is provided below the water pipe 28 of the heat exchanger 22, and the condensed water 58 recovered in the recovery hopper 60 is neutralized through the pipe 62. 64. The neutralizer 64 is filled with a neutralizing agent 66 such as alkaline to neutralize the acidic condensed water 58. The neutralized condensed water 58 is discharged to the outside through the pipe 68.
[0025]
Next, FIG. 2 shows an embodiment of the hot water supply control unit. This hot water supply control unit is provided with a control device 70 as a control means constituted by a microcomputer or the like. The control device 70 includes a CPU as a calculation means, a ROM and a RAM as storage means, and the ROM includes Detection data and the like are stored in a program for controlling hot water supply and the RAM.
[0026]
A set temperature is applied from the temperature setter 72 to the control device 70, and detection outputs from

various temperature sensors

44, 48, 52, a water amount sensor 46, and the like are taken in. The control outputs are the fuel on-off valve 14 and the fuel proportional valve 16. , The variable orifice 56, the water amount control valve 50, the fan motor 74 of the air supply fan 7, and the like.
[0027]
Next, the operation will be described. As shown in FIG. 3, when the fuel gas G is burned by the burner 6, combustion exhaust EG is generated. The amount of heat that the combustion exhaust EG has is H₀, The amount of exchange heat on the heat exchanger 20 side is H₁, T₁The amount of exchange heat on the heat exchanger 22 side is H₂, T₂Then, the amount of heat H of the combustion exhaust EG₀To heat exchanger 20 side heat quantity H₁Is absorbed and the amount of heat (H₀-H₁) Of the combustion exhaust EG flows, and the amount of heat of the combustion exhaust EG passing through the heat exchanger 22 is (H₀-H₁-H₂)
[0028]
Therefore, assuming that the bypass line 54 side is closed, the water temperature t₀When the water supply W is performed, the water temperature t on the outlet side of the heat exchanger 22, that is, on the inlet side of the heat exchanger 20.₁Is (t₀+ Δt₂), The hot water flows to the heat exchanger 20 side, and the tapping temperature t₂(T₀+ Δt₂+ Δt₁)
[0029]
In this case, if the temperature of the combustion exhaust EG obtained by the burner 6 is 1500 ° C., the temperature of the combustion exhaust EG that has passed through the heat exchanger 20 decreases to 200 ° C., and further the combustion exhaust EG that has passed through the heat exchanger 22. The temperature of this will drop to 80 ° C.
[0030]
At this time, heat quantity H₀Heat of exchange for H₁Ratio (H₁/ H₀) Is H₁/ H₀= 80%, heat H₀Heat of exchange for H₂Ratio (H₂/ H₀) Is H₂/ H₀= 10%, (H₁+ H₂) / H₀= 90% and Δt₂: Δt₁= 10: 80, H₁: H₂= Δt₁: Δt₂It is.
[0031]
As shown in FIG. 4 (a), the sensible heat in the combustion exhaust can be recovered to a heat exchange efficiency of 90%, and the latent heat is recovered when the heat exchange efficiency exceeds 90%. Therefore, when a heat exchanger having a heat exchange efficiency of 90% is used for the heat exchanger 20 as shown in FIG. 4B, theoretically, all of the sensible heat should be recovered. In this case, 85% of the sensible heat and about 5% of the latent heat are recovered. At that time, the heat exchanger 20 is partly lowered to a dew point temperature (40 to 50 ° C.) or less due to the endothermic heat absorption. As a result, condensed water is generated on the surface of the heat exchanger 20, and since this condensed water is acidic, it causes corrosion. For this reason, as shown in FIG. 4C, the maximum heat exchange efficiency (for example, 80% heat exchange efficiency at the time of maximum combustion) that can recover only sensible heat on the heat exchanger 20 side is set, and the remaining The heat is absorbed by the heat exchanger 22 made of an acid-resistant material to achieve high efficiency.
[0032]
By the way, since the temperature of the combustion exhaust gas that has passed through the heat exchanger 20 decreases to about 200 ° C., a part of the heat-absorbing fins 26 of the water pipe 24 of the heat exchanger 20 is lowered, that is, 40 ° C. to 50 ° C. or less. There is a risk that it will be cooled to the dew point temperature and cause condensed water. This is the water supply temperature t₀Also occurs. In order to prevent such a decrease in temperature below the dew point temperature, it is necessary to raise the temperature of the hot water passing through the water pipe 24 and raise the temperature of the heat sink fins 26 above the dew point temperature. As a countermeasure on the heat exchanger 20 side, the heat absorption amount from the heat absorption fins 26 to the water pipe 24 is adjusted so that the heat exchange surface of the heat absorption fins 26 becomes higher than the dew point temperature. That is, as shown in FIG. 5, the endothermic amount of the endothermic fin 26 can be realized by adjusting the distance L between the endothermic fin 26 and the water pipe 24 and the thickness of the endothermic fin 26. As a result, it is possible to prevent condensation on the exhaust side, that is, the downstream side of the heat exchanger 20 to some extent. In this case, the water supply W is the amount of heat H on the upstream side.₀The water temperature t₀Is below the water pipe 24 (t₀+ Δt_1a) And the rising temperature Δt_1aIs the amount of heat H_1aCorresponding to For this reason, the amount of heat (H₀-H_1a), And the water temperature (t₀+ Δt₁) Hot water.
[0033]
Then, in order to raise the temperature of the heat sink fin 26 to the dew point temperature or more by the amount of water passing through the bypass pipe 54, the temperature sensor 48 detects the temperature of the hot water on the outlet side of the heat exchanger 20, and according to the detected temperature. By adjusting the opening degree of the variable orifice 56, the ratio of the amount of water flowing to the bypass conduit 54 side and the heat exchanger 20 side is changed. That is, the amount of water on the bypass conduit 54 side can be reduced, the amount of water on the heat exchanger 20 side can be increased, and the hot water temperature on the water tube 24 side can be raised, and the heat exchanger 20 side can be lowered to the dew point temperature or lower. Can be prevented, and condensation on the heat exchanger 20 side can be prevented.
[0034]
In this case, if the ratio of the amount of water on the bypass conduit 54 side and the amount of water on the heat exchanger 20 side is 1: 1, the water supply W that has passed through the water pipe 28 of the heat exchanger 22 is the amount of heat H.₂The water supply W by Δt₂Only the temperature can be raised. FIG. 6 shows an equivalent circuit in this case, and this hot water is diverted, for example, 1: 1 to the bypass conduit 54 and the heat exchanger 20 side, and the amount of heat H on the heat exchanger 20 side is shown.₁Is absorbed and the hot water is further Δt₁Only warm up. In this case, the temperature ta of the hot water on the bypass line 54 side is
ta = (t₀+ Δt₂(1)
The temperature tb of the hot water on the heat exchanger 20 side is
tb = (t₀+ Δt₂+ Δt₁(2)
It is.
[0035]
Since the mixing ratio is 1: 1, the tapping temperature tc of the mixing pipe 57 is

It is. Here, when there is no bypass line 54 or when the variable orifice 56 is closed, the tapping temperature td of the mixing line 57 is:
td = t₀+ Δt₂+ Δt_1b ... (4)
It becomes.
[0036]
Here, if it is assumed that the tapping temperatures tc and td are the same, the amount of water on the heat exchanger 20 side is double that in the case where there is the bypass conduit 54 when there is no bypass conduit 54.₁: Δt_1b= 2: 1 From the relationship
Δt_1b= Δt₁/ 2 (5)
It becomes. As a result, when the hot water is diverted through the bypass pipe 54 and merged in the mixing pipe 57, the hot water temperature of the water pipe 24 of the heat exchanger 20 can be increased, and condensation on the heat exchanger 20 side can be prevented. it can.
[0037]
In addition, an increase in heat exchange efficiency due to an increase in the amount of water passing through the heat exchanger 20 can be expected, heat recovery efficiency is high, and fuel consumption can be reduced.
[0038]
By the way, in this heat exchange device and hot water supply device, the relationship between the bypass pipe 54 and the heat recovery rate of the heat exchanger 20, that is, the influence of the diversion by the bypass pipe 54 on the heat recovery rate of the heat exchanger 20 is seen. As described above, the heat exchanger 20 is heated to about 1500 ° C., while the water temperature is several tens of degrees Celsius, so that when the bypass pipe 54 is not provided, the heat exchange amount of the heat exchanger 20 increases. When viewed from the heating temperature 1500 ° C. of the heat exchanger 20, the temperature difference is negligible, and the diversion by the bypass pipe 54 does not affect the heat absorption rate of the heat exchanger 20.
[0039]
Further, when looking at the relationship between the bypass pipe 54 and the heat exchange efficiency of the heat exchanger 20, that is, the influence of the diversion by the bypass pipe 54 on the heat exchange efficiency of the heat exchanger 20, the bypass pipe 54 is provided. The diversion causes the temperature difference to be slightly reduced before and after heating by the heat exchanger 20, and as a result, the heat transfer coefficient in the pipe due to the decrease in the pipe flow velocity of the water pipe 24 of the heat exchanger 20, thereby reducing the heat exchanger. The heat exchange efficiency of 20 is slightly reduced. However, when there is no bypass line 54, the heat exchange rate of the heat exchanger 20 is 80%, and when the bypass line 54 is attached, the heat exchange rate of the heat exchanger 20 is about 78 to 79%. In addition, prevention of dew condensation by the installation of the bypass pipe line 54 is advantageous.
[0040]
Further, looking at the relationship between the amount of tapping water and the heating temperature, when the tapping amount is made the same and the amount of water in the heat exchanger 20 is suppressed, that is, the heat exchanger 20 side and the bypass line 54 side without changing the total flow rate. If the distribution ratio is changed and the amount of water in the heat exchanger 20 is reduced, the heat exchange efficiency of the heat exchanger 20 is lowered according to the flow rate, and the heating temperature of the heat exchanger 20 is raised. Moreover, when the amount of hot water is made the same and the amount of water on the heat exchanger 20 side is increased, the heating temperature on the heat exchanger 20 side is lowered.
[0041]
The heat exchange efficiency and heat recovery rate of the heat exchanger 20 itself can be adjusted by the protruding length L and thickness of the heat sink fin 26 on the heat exchanger 20 side. There is a range, for example, a dew point temperature or higher and an oxidation temperature (250 ° C.) or lower is preferable, and it is inconvenient whether it is higher or lower than this range. As for the thickness of the heat sink fin 26, when copper is used as the material, the durable element is stronger than the heat transfer element. It is necessary to increase and decrease the pitch.
[0042]
By the way, the

heat exchangers

20 and 22 are connected in series, and the fluid resistance on the water tube 24 side is R.₁, Each fluid resistance on the water pipe 28 side is R₂Then, the water flow path can be represented by an equivalent circuit shown in FIG. When the parallel number of the pipes 30 to 34 on the water pipe 28 side is n, the total water flow resistance R is
R = R₁+ R₂/ N (6)
Thus, the total water resistance R is significantly reduced by paralleling the pipes 30 to 34 on the water pipe 28 side. Therefore, the hot water supply apparatus can obtain a stable amount of hot water.
[0043]
The amount of hot water obtained from the mixing pipe 57 can be controlled by the water amount control valve 50, and the opening of the variable orifice 56 is adjusted according to the amount of hot water to control the flow rate on the heat exchanger 20 side. be able to. If the flow rate on the heat exchanger 20 side is set large, the hot water temperature of the water pipe 24 of the heat exchanger 20 can be increased, and condensation on the heat exchanger 20 side can be prevented.
[0044]
Further, the temperature of the hot water obtained from the mixing pipe 57 is detected by the temperature sensor 52, and the hot water at the set temperature can be discharged by adjusting the amount of combustion of the burner 6 by the detected temperature. In this case as well, the flow rate on the heat exchanger 20 side can be controlled according to the set temperature, and dew condensation on the heat exchanger 20 side can be achieved by increasing the hot water temperature of the water pipe 24 of the heat exchanger 20. Can be prevented.
[0045]
Next, another embodiment of the present invention shown in FIG. 8 will be described. A bypass line 55 is installed between the line 38 and the line 42 on the outlet side of the heat exchanger 20 to heat the water supply W. For example, the water supply W may be diverted at a ratio of 1: 1 on the inlet side of the exchanger 22 and mixed with the hot water on the outlet side of the heat exchanger 20. FIG. 9 shows an equivalent circuit in this case, and the temperature of the feed water on the bypass line 55 side is t₀The temperature te of hot water heated by the

heat exchangers

20 and 22 is
te = t₀+ Δt₂+ Δt₁ ... (7)
It is.
[0046]
Since the mixing ratio is 1: 1, the tapping temperature tf of the mixing pipe 57 is

It becomes. However, ΔT_a= (Δt₂+ Δt₁) / 2. Here, when there is no bypass line 55 or when the variable orifice 56 is closed to obtain the tapping temperature tg, the same as the tapping temperature td shown in the equation (4),

It becomes. However, ΔT_b= Δt₂+ Δt_1bIt is.
[0047]
ΔT_a: ΔT_bSince the ratio becomes = 2: 1, the temperature of the hot water in the water pipe 24 of the heat exchanger 20 can be increased by diverting the water supply W through the bypass pipe 55 and joining it in the mixing pipe 57. In this case as well, an increase in heat exchange efficiency by increasing the amount of water passing through the heat exchanger 20 can be expected, heat recovery efficiency is high, and fuel consumption can be reduced.
[0048]
In the above embodiment, the heat exchange device applied to the hot water supply device has been described as an example. However, the heat exchange device of the present invention can be applied to other than the hot water supply device, for example, a heat medium as a fluid to be heated. It can also be applied to a heating apparatus that heats.
[0049]
【The invention's effect】
  As described above, according to the present invention, the following effects can be obtained.
  a According to the first aspect of the present invention, since the heated fluid heated by the second heat exchanger is mixed with the heated fluid heated by the first and second heat exchangers, the first heat exchange Heating temperature on the heat exchanger side can be increased, condensation on the first heat exchanger side can be suppressed, corrosion on the first heat exchanger side due to condensed water, reduction in strength and damage due to corrosion can be prevented, and heat recovery Effective utilization of efficiency can be achieved, and fuel consumption can be reduced.In addition, since the heat receiving pipe of the second heat exchanger has a plurality of pipes arranged in parallel to expand the pipe cross-sectional area and reduce the fluid resistance, the desired flow rate and flowing water speed are ensured to increase the heat exchange efficiency. Can contribute to the suppression of fuel consumption.
  b According to the second aspect of the present invention, since the heated fluid before heating and the heated fluid heated by the first and second heat exchangers are mixed, the heating temperature on the first heat exchanger side It is possible to reduce the dew condensation on the first heat exchanger side and prevent the first heat exchanger side from being corroded by condensate, preventing the deterioration of strength and damage due to corrosion, and the effective use of heat recovery efficiency Consumption can be reduced.
  c According to the third aspect of the present invention, the temperature of the fluid to be heated of the heat receiving pipe on the first heat exchanger side is detected, and the heat receiving pipe of the first heat exchanger or the first and Since the flow rate of the heat receiving pipe of the second heat exchanger is adjusted, a temperature drop on the heat receiving pipe side of the first heat exchanger can be prevented, and condensation on the first heat exchanger side can be prevented.
  d According to the present invention of claim 4, since the heating temperature on the first heat exchanger side is controlled by controlling the combustion amount of the combustion means, the heating temperature on the first heat exchanger side can be increased, Condensation on the first heat exchanger side can be suppressed.
  e According to the present invention of claim 5, since the endothermic amount is adjusted by the protruding length or thickness of the heat sink fin of the heat receiving tube of the first heat exchanger, the first heat coupled with the heating control of the fluid to be heated. It is possible to prevent the heat sink fin of the heat receiving pipe of the exchanger from being lowered, and to suppress dew condensation.
  f According to the present invention according to claim 6, since the outer wall member of the second heat exchanger is made of an acid-resistant material such as titanium or stainless steel, damage due to acidic condensed water can be prevented, and the condensation can be prevented. Water can be rendered harmless by recovery and neutralization.
  g According to the invention of claim 7,,By parallelizing multiple pipes and expanding the pipe cross-sectional area,Heat receiving pipeSince the fluid resistance is lowered, it is possible to secure a desired flow rate and flowing water speed, increase heat exchange efficiency, and contribute to suppression of fuel consumption.
  h According to the present invention according to claim 8, hot water can be efficiently supplied, damage from condensed water can be prevented, and a highly durable hot water supply apparatus can be provided.
[Brief description of the drawings]
FIG. 1 is a piping diagram showing an embodiment of a heat exchange device and a hot water supply device of the present invention.
FIG. 2 is a block diagram illustrating a configuration of a control unit.
FIG. 3 is a diagram showing heat generated by a burner and heat exchange by first and second heat exchangers.
FIG. 4 is a diagram showing heat exchange and thermal efficiency of a heat exchanger.
FIG. 5 is a diagram showing dew condensation on the first heat exchanger side and its prevention.
FIG. 6 is a diagram showing hot water mixing by a bypass line.
FIG. 7 is a circuit diagram showing an equivalent circuit based on fluid resistance in the first and second heat exchangers.
FIG. 8 is a piping diagram showing another embodiment of a bypass pipe line.
FIG. 9 is a diagram showing hot water mixing by a bypass line.
[Explanation of symbols]
6 Burner (combustion means)
8 Exhaust passage
G Fuel gas
W water supply
EG combustion exhaust
20 First heat exchanger
22 Second heat exchanger
24 Water pipe (heat receiving pipe)
26 Endothermic fin
28 Water pipe (heat receiving pipe)
30, 32, 34 pipelines
48 Temperature sensor (temperature detection means)
54, 55 Bypass pipeline
56 Variable orifice (flow rate adjusting means)
58 Condensate
60 Recovery hopper
70 Control device (control means)

Claims

燃料を燃焼させて燃焼排気を排気通路に流す燃焼手段と、
前記排気通路の上流側に設置されて受熱管に流れる被加熱流体に前記燃焼排気から主として顕熱を吸収させる第１の熱交換器と、
この第１の熱交換器の前記受熱管に直列に接続されるとともに、前記排気通路の下流側に設置された受熱管に流れる前記被加熱流体に、前記第１の熱交換器を通過した前記燃焼排気から主として潜熱を吸収させる第２の熱交換器と、
前記第２の熱交換器の前記受熱管を通過した加熱後の前記被加熱流体を前記第１の熱交換器の前記受熱管に流す管路と、前記第１の熱交換器の前記受熱管を通過した加熱後の前記被加熱流体を流す管路との間に接続され、前記第２の熱交換器の前記受熱管を通過した前記被加熱流体の一部を、前記第１の熱交換器の前記受熱管を通過した加熱後の前記被加熱流体に混合させるバイパス管路と、
このバイパス管路に設置されて前記被加熱流体の流量を調整する可変オリフィスと、
前記第１の熱交換器の前記受熱管を通過した前記被加熱流体と前記バイパス管路を通過させた前記被加熱流体とを混合して出湯させる混合管路と、
この混合管路に設置されて出湯量を制御する水量制御弁と、
を備え、前記第２の熱交換器の前記受熱管を複数の並列化した管路により構成し、前記第２の熱交換器の前記受熱管の管路断面を前記第２の熱交換器の前後に接続される前記管路より増大させ、前記水量制御弁で制御される前記出湯量に応じて前記可変オリフィスの開度を調整し、前記第１の熱交換器の前記受熱管に流れる前記被加熱流体の流量を制御することを特徴とする熱交換装置。Combustion means for burning fuel and flowing combustion exhaust gas into an exhaust passage;
A first heat exchanger that is installed on the upstream side of the exhaust passage and that absorbs mainly sensible heat from the combustion exhaust to a heated fluid that flows to a heat receiving pipe;
The fluid that is connected in series to the heat receiving pipe of the first heat exchanger and that flows through the heat receiving pipe installed on the downstream side of the exhaust passage passes through the first heat exchanger. A second heat exchanger that mainly absorbs latent heat from the combustion exhaust;
A conduit for flowing the heated fluid that has passed through the heat receiving pipe of the second heat exchanger to the heat receiving pipe of the first heat exchanger; and the heat receiving pipe of the first heat exchanger A part of the fluid to be heated which is connected to a pipe line through which the fluid to be heated after passing through the second heat exchanger passes and which has passed through the heat receiving pipe of the second heat exchanger. A bypass line to be mixed with the heated fluid that has passed through the heat receiving pipe of the vessel; and
A variable orifice installed in this bypass line to adjust the flow rate of the heated fluid;
A mixing pipe that mixes the heated fluid that has passed through the heat receiving pipe of the first heat exchanger and the heated fluid that has passed through the bypass pipe to discharge hot water;
A water amount control valve installed in this mixing line to control the amount of hot water;
The heat receiving pipe of the second heat exchanger is configured by a plurality of parallel pipe lines, and the pipe cross section of the heat receiving pipe of the second heat exchanger is the same as that of the second heat exchanger. The opening of the variable orifice is adjusted in accordance with the amount of hot water controlled by the water amount control valve, increased from the pipe connected to the front and rear, and flows to the heat receiving pipe of the first heat exchanger A heat exchange device that controls a flow rate of a fluid to be heated.

燃料を燃焼させて燃焼排気を排気通路に流す燃焼手段と、
前記排気通路の上流側に設置されて受熱管に流れる被加熱流体に前記燃焼排気から主として顕熱を吸収させる第１の熱交換器と、
この第１の熱交換器の前記受熱管に直列に接続されるとともに、前記排気通路の下流側に設置された受熱管に流れる前記被加熱流体に、前記第１の熱交換器を通過した前記燃焼排気から主として潜熱を吸収させる第２の熱交換器と、
前記第２の熱交換器の前記受熱管に加熱前の前記被加熱流体を流す管路と前記第１の熱交換器の前記受熱管を通過した加熱後の前記被加熱流体を流す管路との間に接続され、前記第２の熱交換器の前記受熱管の通過前の前記被加熱流体の一部を前記第１の熱交換器の前記受熱管を通過した前記被加熱流体に混合させるバイパス管路と、
このバイパス管路に設置されて前記被加熱流体の流量を調整する可変オリフィスと、
前記第１の熱交換器の前記受熱管を通過した前記被加熱流体と前記バイパス管路を通過させた前記被加熱流体とを混合して出湯させる混合管路と、
この混合管路に設置されて出湯量を制御する水量制御弁と、
を備え、前記第２の熱交換器の前記受熱管を複数の並列化した管路により構成し、前記第２の熱交換器の前記受熱管の管路断面を前記第２の熱交換器の前後に接続される前記管路より増大させ、前記水量制御弁で制御される前記出湯量に応じて前記可変オリフィスの開度を調整し、前記第１の熱交換器の前記受熱管に流れる前記被加熱流体の流量を制御することを特徴とする熱交換装置。Combustion means for burning fuel and flowing combustion exhaust gas into an exhaust passage;
A first heat exchanger that is installed on the upstream side of the exhaust passage and that absorbs mainly sensible heat from the combustion exhaust to a heated fluid that flows to a heat receiving pipe;
The fluid that is connected in series to the heat receiving pipe of the first heat exchanger and that flows through the heat receiving pipe installed on the downstream side of the exhaust passage passes through the first heat exchanger. A second heat exchanger that mainly absorbs latent heat from the combustion exhaust;
A conduit for flowing the heated fluid before heating to the heat receiving tube of the second heat exchanger, and a conduit for flowing the heated fluid after passing through the heat receiving tube of the first heat exchanger; And a part of the heated fluid before passing through the heat receiving tube of the second heat exchanger is mixed with the heated fluid that has passed through the heat receiving tube of the first heat exchanger. A bypass line;
A variable orifice installed in this bypass line to adjust the flow rate of the heated fluid;
A mixing pipe that mixes the heated fluid that has passed through the heat receiving pipe of the first heat exchanger and the heated fluid that has passed through the bypass pipe to discharge hot water;
A water amount control valve installed in this mixing line to control the amount of hot water;
The heat receiving pipe of the second heat exchanger is configured by a plurality of parallel pipe lines, and the pipe cross section of the heat receiving pipe of the second heat exchanger is the same as that of the second heat exchanger. The opening of the variable orifice is adjusted in accordance with the amount of hot water controlled by the water amount control valve, increased from the pipe connected to the front and rear, and flows to the heat receiving pipe of the first heat exchanger A heat exchange device that controls a flow rate of a fluid to be heated.

前記第１の熱交換器側の前記受熱管を流れる前記被加熱流体の温度を検出する温度検出手段を備え、前記被加熱流体の温度に応じて前記可変オリフィスの開度を調整して前記被加熱流体の流量を制御し、前記第１の熱交換器を露点温度以上に加熱することを特徴とする請求項１又は２記載の熱交換装置。 Temperature detecting means for detecting the temperature of the heated fluid flowing through the heat receiving pipe on the first heat exchanger side, and adjusting the opening of the variable orifice according to the temperature of the heated fluid to adjust the opening of the variable fluid. The heat exchange device according to claim 1 or 2, wherein a flow rate of the heating fluid is controlled to heat the first heat exchanger to a dew point temperature or higher.

前記被加熱流体の設定温度により前記燃焼手段の燃焼量を制御手段によって制御することを特徴とする請求項１又は２記載の熱交換装置。 The heat exchange device according to claim 1 or 2, wherein a combustion amount of the combustion means is controlled by a control means according to a set temperature of the fluid to be heated.

前記第１の熱交換器の前記受熱管の吸熱フィンの突出長又は厚さによって吸熱量を調整したことを特徴とする請求項１又は２記載の熱交換装置。 3. The heat exchange device according to claim 1, wherein the heat absorption amount is adjusted by a protruding length or thickness of a heat absorption fin of the heat receiving pipe of the first heat exchanger.

前記第２の熱交換器の外壁部材を耐酸性素材で構成し、かつ、前記第２の熱交換器の外表面に生じた凝縮水を回収する手段を備え、回収した前記凝縮水を中和させることを特徴とする請求項１又は２記載の熱交換装置。 The outer wall member of the second heat exchanger is made of an acid-resistant material, and includes means for recovering condensed water generated on the outer surface of the second heat exchanger, and neutralizes the recovered condensed water The heat exchange device according to claim 1 or 2, wherein

前記第１の熱交換器の受熱管を複数の管路で構成し、前記第１の熱交換器の前記受熱管の管路断面を前記第１の熱交換器の前後に接続される前記管路より増大させたことを特徴とする請求項１又は２記載の熱交換装置。 The heat receiving pipe of the first heat exchanger is constituted by a plurality of pipes, and the pipe connected to the cross section of the heat receiving pipe of the first heat exchanger before and after the first heat exchanger. The heat exchange device according to claim 1 or 2, wherein the heat exchange device is larger than the passage.

請求項１〜７に記載の熱交換装置を用いて給水を加熱し、給湯することを特徴とする給湯装置。 A hot water supply apparatus for heating hot water using the heat exchange device according to claim 1 to supply hot water.