JP3977605B2 - Waste heat recovery system - Google Patents

Description

【００２９】
即ち、「給湯負荷」は、その時点の季節及び時刻における次回の給湯予想量であるから、例えば、７月Ｘ日、１８：００にＣＧＳ運転を開始する場合、給湯負荷は６０００ｋｃａｌで計算し、また、２月Ｙ日、５：００にＣＧＳ運転を開始する場合、給湯負荷は２０００ｋｃａｌで計算する。
【００３０】
また、「積算出力」は、制御部１２４に内蔵されている給湯積算出力カウンタ１２５を用いて求められる給湯及び注湯に使用された出力の合計である。即ち、給湯需要があると思われる時間帯で、バックアップと蓄熱利用を含めた全ての出力を求め、そのデータをエンジン運転時間にフィードバックする。
【００３１】
また、貯湯タンク３４のタンク蓄熱量の計算は、例えば、タンク容量を２００リットルとし、図５に示すように、貯湯タンク３４の各ゾーン１〜７は同容量であり、１ゾーン当たりの温水量は約２８．６リットルとなる。ここで、水温を冬期で５℃、春秋期で１５℃、夏期で２５℃と定義すると、各ゾーンの熱量Ｑ（ｋｃａｌ）は、
【００３２】
Ｑ＝２８．６×｛（上側検出温度＋下側検出温度）／２−水温｝・・・（２）
となり、タンク蓄熱量Ｑｍは全ゾーン１〜７の合計である。但し、一つの条件として｛（上側検出温度＋下側検出温度）／２−水温｝＜１０℃の場合には、そのゾーンは零とする。例えば、冬期、温度センサ６４１の検出温度が７５℃、温度センサ６４３の検出温度が７０℃のとき、ゾーン１の熱量Ｑ₁ は、
【００３３】
Ｑ₁ ＝２８．６×｛（７５＋７０）／２−５｝＝１９３０．５（ｋｃａｌ）・・・（３）
となる。なお、温度センサ６４１〜６５０の中、温度センサ６４２、６４９は蓄熱量Ｑｍの計算には使用しない。
【００３４】
そして、ステップＳ５で前記要求蓄熱量が１０００ｋｃａｌ以上であると判定されたとき、又はステップＳ３で暖房命令が発せられているとき、ステップＳ６に移行し、貯湯タンク３４の最下部側の温度センサ６５０の検出温度が所定温度、例えば、４０℃以上か否かを判定し、所定温度以下の場合、ステップＳ７に移行する。ステップＳ７では、前回のエンジン２の停止から所定時間、例えば、６０分以上経過したか否かが判定され、所定時間以下の場合には、エンジン保護のためエンジン２の起動を禁止する。即ち、貯湯タンク３４の最下部側の湯温が低温であることを確認し、エンジン２のオーバーヒートを防止している。そして、所定時間が経過している場合には、ステップＳ８に移行し、エンジン２の起動を行うとともに、暖機運転を行う。この暖機運転では、三方弁３０を切り換えてバイパス路２８を介して排熱回収路６を狭小化し、熱媒温度の急激な立上りを行う。
【００３５】
そして、この暖機運転の後、ステップＳ９に移行し、エンジン２の入口側の熱媒４の温度、即ち、熱媒４の戻り温度が所定温度、例えば、６５℃になるように制御する。この一定温度制御は、温度センサ８、１０の検出温度を監視しながら、直流モータ１７の回転数を増減させ、循環ポンプ１６で圧送される熱媒４の流量を加減することにより行われる。
【００３６】
次に、図６は、図４のステップＳ１の三方弁１４、３０、４２、４４等の弁初期位置設定のサブルーチンを示している。即ち、このサブルーチンがスタートすると、ステップＳ１０１で、三方弁４２はＤ−Ａ方向、三方弁４４はＤ−Ｃ（閉止）方向、三方弁３０はＣ−Ａ方向、三方弁１４はＣ−Ａ方向に切り換えられる。この結果、常時起動プログラムの実行が準備される。
【００３７】
次に、図７は、図４のメインルーチンのステップＳ２のサブルーチンであるエンジン異常停止制御を示している。即ち、このサブルーチンがスタートすると、ステップＳ２０１では、エンジン２の運転状態が「運転」であるか否かが判定され、運転状態にあるときはステップＳ２０２に移行し、所定時間として例えば、１０秒経過の後、ステップＳ２０３に移行し、ガス弁が閉（ＯＦＦ）であるか否かが判定され、閉でない場合にはステップＳ２０１に戻り、閉止している場合にはステップＳ２０４に移行し、エンジン停止を行った後、ステップＳ２０５に移行し、表示器１２６にエンジン異常停止を行った旨の表示としてアラーム表示を行う。
【００３８】
また、ステップＳ２０１で、エンジン２が運転状態でない場合には、ステップＳ２０６に移行し、所定時間として例えば、１０秒経過の後、ステップＳ２０７に移行し、ガス弁が開（ＯＮ）しているか否かが判定され、開でない場合にはステップＳ２０１に戻り、開の場合にはステップＳ２０８に移行し、エンジン停止を行った後、ステップＳ２０９に移行し、表示器１２６に「エンジン停止せず」とのアラーム表示を行う。
【００３９】
次に、図８は、図４のメインルーチンのステップＳ２のサブルーチンであるエンジン運転許可制御を示している。即ち、このサブルーチンがスタートすると、ステップＳ２１１では、エンジン運転が許可時間であるか否かが判定され、運転許可時間にある場合にはステップＳ２１２に移行し、エンジン運転許可指示として「許可」を出力し、また、エンジン運転許可時間でない場合にはステップＳ２１３に移行し、エンジン運転許可を禁止する指示として「禁止」を出力する。
【００４０】
次に、図９は、図４のメインルーチンのステップＳ２のサブルーチンであるエンジン停止制御を示している。即ち、このサブルーチンがスタートすると、ステップＳ２１５では、エンジン２の電源をＯＦＦにした後、ステップＳ２１６に移行し、弁初期位置制御（図６）を実行した後、ステップＳ２１７に移行し、エンジン２の運転状態を停止状態にする。
【００４１】
次に、図１０は、図４のメインルーチンのステップＳ２のサブルーチンであるエンジン強制停止制御を示している。即ち、このサブルーチンがスタートすると、ステップＳ２２１では、強制停止入力手段として例えば、Ｅｓｃキーが押されたか否かが判定され、このＥｓｃキーが押されたとき、ステップＳ２２２に移行し、エンジン停止制御（図９）を実行し、制御を終了する。
【００４２】
次に、図１１は、図４のメインルーチンのステップＳ２のサブルーチンである暖房運転命令制御を示している。即ち、このサブルーチンがスタートすると、ステップＳ２２５では、暖房装置側の暖房命令手段として端末スイッチがＯＮ、又は双方向通信の暖房命令がＯＮしたか否かが判定され、暖房命令が指示されたとき、ステップＳ２２６に移行し、暖房命令を「ＯＮ」とし、制御手段であるバックアップインテリ基板のＥコン端子を「ＯＮ」とする。また、ステップＳ２２７では、暖房装置側の暖房命令手段として端末スイッチのＯＦＦと、双方向通信の暖房命令のＯＦＦとが成立しているか否かが判定され、暖房停止命令が指示されたとき、ステップＳ２２８に移行し、暖房命令を「ＯＦＦ」とし、制御手段であるバックアップインテリ基板のＥコン端子を「ＯＦＦ」とする。
【００４３】
次に、図１２は、図４のメインルーチンのステップＳ２のサブルーチンである給湯積算出力カウンタ１２５の制御を示している。即ち、このサブルーチンがスタートすると、ステップＳ２３１では、エンジン運転が「許可」であるか否かが判定され、許可の場合にはステップＳ２３２に移行し、カウンタリセットを行う。即ち、給湯積算出力カウンタ１２５に格納されている熱量Ｑｃを０ｋｃａｌとした後、ステップＳ２３３に移行し、水温を決定する。即ち、冬期では５℃、春秋期では１５℃、夏期では２５℃を設定した後、ステップＳ２３４に移行し、混合温サーミスタである温度センサ８２の湯温測定を行う。
【００４４】
そして、ステップＳ２３５では、給湯量を検出する流量センサ７８が所定流量として例えば、１リットルカウントしたか否かを判定し、１リットルカウントを行った場合、ステップＳ２３６に移行する。ステップＳ２３６では、１リットル当たりの熱量計算として給湯積算出力熱量Ｑｃを演算する。即ち、この給湯積算出力熱量Ｑｃ（ｋｃａｌ）は、
【００４５】
Ｑｃ＝（湯温−水温）×１（ｋｃａｌ） ・・・（４）
で算出される。
【００４６】
そして、ステップＳ２３７に移行し、エンジン運転許可が「禁止」されているか否かが判定され、エンジン運転が禁止されている場合にはステップＳ２３１に復帰し、エンジン運転が禁止されていない場合にはステップＳ２３４に移行し、ステップＳ２３４〜ステップＳ２３６の処理を実行する。
【００４７】
次に、図１３は、図４のメインルーチンのステップＳ２のサブルーチンである弁異常チェック制御を示している。即ち、このサブルーチンがスタートすると、ステップＳ２４１では、弁出力と切換状態を表すリミットが一致しているか否かが判定され、一致していない場合にはステップＳ２４２で所定時間として例えば、３０秒経過の後、ステップＳ２４３に移行し、表示器１２６に三方弁１４、３０、４２、４４等が異常である旨をアラームによって告知する。また、ステップＳ２４１で弁出力とリミットが一致している場合には、ステップＳ２４４に移行し、正常である旨出力し、表示器１２６にそれを表示する。
【００４８】
次に、図１４は、図４のメインルーチンのステップＳ２のサブルーチンである温度センサ異常チェック制御を示している。即ち、このサブルーチンがスタートすると、ステップＳ２５１では、接続線等に断線又は短絡の異常が生じているか否かが判定され、異常が生じている場合にはステップＳ２５２に移行し、表示器１２６に温度センサ８、１０等が異常である旨をアラームによって告知する。また、ステップＳ２５１で異常が生じていない場合には、ステップＳ２５３に移行し、正常である旨出力し、表示器１２６にそれを表示する。
【００４９】
次に、図１５は、図４に示すフローチャートのステップＳ８のサブルーチンであるエンジン起動及び暖機運転の制御を示している。
【００５０】
ステップＳ８０１では、温水３２の自然対流を防止するため、三方弁４２をＤ−Ａ方向、三方弁４４をＤ−Ｃ方向、暖機回路を構成するため、三方弁３０をＣ−Ａ方向、三方弁１４をＣ−Ａ方向に切り換えるとともに、循環ポンプ１６を中回転に設定した後、ステップＳ８０２に移行し、温度センサ１０の検出温度が所定温度、例えば、５５℃以下であるか否かを判定し、この５５℃を超えている場合、ステップＳ８０３に移行し、所定時間として例えば、２０分が経過したか否かを判定する。５５℃を超えて２０分が経過している場合には何らかの異常が発生していることが予想されるので、ステップＳ８０４に移行し、表示器１２６にアラームを発生させ、「異常停止」を告知する。このとき、エンジン２の停止モードに移行することになる。
【００５１】
ステップＳ８０２で検出温度が所定温度以下の場合、ステップＳ８０５に移行してエンジン２の電源をＯＮとし、ステップＳ８０６に移行してエンジン起動接点を所定時間、例えば、５秒間だけＯＮ状態とし、ステップＳ８０７に移行してエンジン起動接点をＯＦＦにした後、所定時間、例えば、３秒間待機し、ステップＳ８０８に移行する。ステップＳ８０８では、ガス弁がＯＮ状態か否かを判定し、ガス弁がＯＮ状態でない場合、ステップＳ８０９に移行し、その起動が所定回数、例えば、５回目か否かを判定する。所定回数以下の場合には、ステップＳ８１０に移行し、所定回数に移行する所定時間、例えば、５秒間待機してステップＳ８０６に戻る。また、ステップＳ８０９でエンジン起動が所定回数に到達している場合、ステップＳ８１１に移行してエンジン停止とし、ステップＳ８１２で表示器１２６にアラームを発生させるとともに、「エンジン起動失敗」を告知させる。この告知によって利用者は、異常を知ることができる。
【００５２】
ステップＳ８０８でガス弁がＯＮに移行したと判定されたとき、ステップＳ８１３に移行してエンジン２は運転状態となり、ステップＳ８１４に移行する。ステップＳ８１４では温度センサ１０の検出温度が所定温度、例えば、６０℃を超えているか否かを判定し、６０℃を超えていない場合、ステップＳ８１５に移行し、所定時間の経過、例えば、２０分が経過したか否かを判定し、所定時間が経過するまで、検出温度の推移を監視する。２０分が経過したにも拘わらず、検出温度が６０℃を超えない場合には、ステップＳ８１６に移行してエンジン停止を行った後、ステップＳ８１７に移行し、表示器１２６にアラームを発生させるとともに、エンジン・インバータ異常を告知させる。この告知によって利用者は、異常を知ることができる。
【００５３】
そして、ステップＳ８１４で温度センサ１０の検出温度が６０℃を超えている場合、暖機運転が正常に行われたことを表し、ステップＳ８１８に移行し、三方弁３０をＢ−Ｃ方向に切り換え、バイパス路２８を切り離した後、メインルーチン（図４）のステップＳ９にリターンし、エンジン２による発電とともに、排熱回収を開始する。
【００５４】
次に、図１６は、図４のステップＳ９のサブルーチンであるエンジン入温度制御（目標値６５℃の制御）を示している。
【００５５】
ステップＳ９０１ではエンジン２が運転状態か否かを常に監視し、ステップＳ９０２では循環ポンプ４５の回転制御等を実行する。即ち、エンジン２に対する熱媒４の入側温度、即ち、温度センサ８の検出温度である戻り温度が所定温度、例えば、６５℃を目標値として循環ポンプ４５の回転制御を行う。なお、この制御の結果、循環ポンプ４５の回転が停止している場合には、三方弁４４をＡ−Ｃ（閉止）方向に切り換え、循環ポンプ４５が回転している場合は三方弁４４をＤ−Ｂ方向に切り換えた後、ステップＳ９０３に移行する。
【００５６】
ステップＳ９０３では、貯湯タンク３４の最下部側の温度センサ６５０の検出温度が所定温度、例えば、５０℃以上か否かを判定し、所定温度以下の場合、ステップＳ９０４に移行する。この場合、始動条件とのヒステリシス温度は例えば、１０℃に設定する。そして、ステップＳ９０４では、エンジン２に対する熱媒４の入側温度、即ち、温度センサ８の検出温度である戻り温度が所定温度、例えば、７５℃以上が所定時間、例えば、１０秒以上か否か、且つ、循環ポンプ４５の回転数が最大か否かを判定する。所定温度が所定時間以下、且つ、循環ポンプ４５の回転数が最大でない場合、ステップＳ９０５に移行する。
【００５７】
ステップＳ９０５では、エンジン２の運転状態が停止か否かを判定し、エンジン２が停止していないとき、即ち、運転状態のとき、ステップＳ９０６に移行し、暖房接点がＯＮ状態か否かを判定する。ＯＮ状態でない場合には、ステップＳ９０７に移行し、エンジン運転が許可されているか否かを判定し、エンジン運転が許可されている場合には、ステップＳ９０８に移行してタンク蓄熱量が（給湯負荷×１．２−積算出力）より多いか否かを判定する。即ち、この判定は、暖房を行っていない場合、エンジン運転許可時間内であれば、この条件成立でエンジン運転停止を行うことを意図している。
【００５８】
ところで、ステップＳ９０３で温度センサ６５０の検出温度が所定温度、即ち、５０℃を超えている場合、又は、ステップＳ９０４で所定温度が所定時間以上、且つ、循環ポンプ４５の回転数が最大である場合には、ステップＳ９０９に移行し、循環ポンプ４５を停止させ、ステップＳ９１０に移行してエンジン停止を行う。ステップＳ９１１では、エンジン停止から所定時間の経過、例えば、３０秒が経過するまで待機した後、ステップＳ９１２に移行し、循環ポンプ１６を停止させた後、図４に示すメインルーチンのステップＳ２に戻る。即ち、循環ポンプ４５を停止させた後、循環ポンプ１６を停止させるのは、貯湯タンク３４側の階層蓄熱の崩れを防止するためである。
【００５９】
また、ステップＳ９０５でエンジン２の停止、ステップＳ９０７でエンジン２の運転禁止、又は、ステップＳ９０８でタンク蓄熱量が（給湯負荷×１．２−積算出力）を超えている場合には、ステップＳ９１３に移行し、エンジン停止を行い、ステップＳ９１４でエンジン停止から所定時間例えば、３０秒が経過するまで待機した後、ステップＳ９１５に移行し、循環ポンプ４５の停止を行い、ステップＳ９１２に移行する。
【００６０】
このように、この排熱回収システムでは、エンジン２の排熱を冷却水又は熱回収水としての熱媒４を循環させ、その排熱回収路６内に熱交換器２４、２６を設けて熱交換させているが、熱媒４の戻り温度を所定温度、例えば、６５℃となるように循環ポンプ１６の回転制御によって熱媒４の流量を加減することで実現している。一方、この熱媒制御に並行して排熱回収路６から熱交換器２４を通して排熱を回収する循環路３６側では、循環ポンプ４５の回転制御により、温水３２の循環量が制御され、貯湯タンク３４への蓄熱量が可変される。したがって、エンジン２の出口側の熱媒４の温度には、循環ポンプ１６による流量制御だけでなく、循環ポンプ４５による温水３２側の流量制御、熱交換器２６側の循環ポンプ１０８による流量制御が影響するので、これらを総合的に制御することにより、所望の温度、即ち、所定幅に制御することができる。なお、この実施例では、熱媒４の戻り温度を所定値として例えば、６５℃±５℃の範囲に制御しているが、エンジン２における熱媒４の戻り温度と出口温度とを所定の温度幅になるように制御してもよく、このような制御であっても同様の効果が得られる。
【００６１】
入水温度や暖房負荷により冷却水戻り温度は変動するが、より効率良くエンジン２を運転させ、より高温水を貯湯タンク３４に蓄熱させるためには、排熱回収側（受熱側）の循環流量を小流量とし、可変させることが必要である。そこで、排熱回収路６には、消費電力が低く、制御性に優れた直流モータ１７で駆動される循環ポンプ１６を設置したので、小流量から大流量までの幅広い流量制御が可能であり、エンジン２に対する熱媒４の戻り温度を効率良く一定に制御することができる。
【００６２】
そして、排熱回収路としての循環路３６では、循環ポンプ４５を適宜作動させることにより、貯湯タンク３４の底部から取り出した水を貯湯タンク３４の上部側へ送りつつ、熱交換器２４によって熱媒４との熱交換を行う結果、貯湯タンク３４の上層部側から積層沸き上げにより蓄熱が行われる。即ち、貯湯タンク３４には、その最下部側の水が取り出され、それが加熱されて高温水となり、この高温水が貯湯タンク３４の上層部に供給され、取り出された水が高温水として上層部に補填される結果、上層部側から下層部に向かって温度の境界層が際立つ温水層が形成されて蓄熱が行われる。このように、貯湯タンク３４には質の高い積層沸き上げが行われる結果、給湯要求があった場合にはその貯湯タンク３４の上層部から温水３２即ち、蓄熱を取り出し、利用することができ、しかも、運転開始時から温水３２を利用することができる。自然対流方式の蓄熱に比較し、運転開始時に高温水が利用できるという利点がある。
【００６３】
また、排熱回収路６には、２つの熱交換器２４、２６が設置されており、暖房要求があった場合には、暖房側の熱交換器２６のみで熱交換を行えばよいが、熱交換器２４側でも熱交換が行われることになる。このような熱交換を放置すると、貯湯タンク３４に自然対流によって温水循環が生じる。即ち、熱交換器２４を通じて熱媒４側に熱が奪われることになり、熱交換器２６で行う熱交換の循環温度の低下が予想される。そこで、この排熱回収システムでは、循環路３６に三方弁４２、４４が設置され、これらの切換えによって循環路３６を閉止状態に制御するので、温水３２に自然対流を発生させることがなく、貯湯タンク３４の蓄熱崩れを防止できるとともに、暖房運転時の熱媒４の温度低下を防止でき、暖房時の温度の立上りを急峻にでき、暖房効率を高めることができる。
【００６４】
【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 エンジン等の熱源に循環させる流体の入口温度、即ち、戻り温度を所定温度に制御するので、排熱回収の最適化を図ることができるとともに、熱源の運転特性の悪化を防止でき、その耐久性を維持することができる。熱源である駆動源にエンジンを使用した場合、運転時間を長くでき、効率的な運転を実現できる。
ｂ エンジン等の熱源に循環させる流体流量を一定にし、又は変化させることと相まって流体の熱を吸収させる水の流量を制御するので、熱源の排熱回収をより最適化できるとともに、熱源の運転特性の悪化を防止でき、その耐久性を維持することができる。
ｃ 直流モータによってポンプを駆動すれば、小流量から大流量まで流量の制御性を高めることができ、消費電力の低減を図ることができる。
ｄ 回収した排熱を以て水の積層沸き上げを行い、上層部側から温水として熱を取り出すので、運転開始とともに熱利用ができ、熱損失を低減して効率の良い蓄熱を実現できるとともに、排熱の利用効率を高めることができる。
ｅ 熱源の運転時、積層沸き上げで蓄熱された温水の自然対流を防止でき、蓄熱損失の低下や利用効率の低下を抑制できる。
ｆ 蓄熱手段の上部から蓄熱された熱を取り出すので、熱損失を低減でき、蓄熱効率を高め、熱の利用効率を高めることができる。
【図面の簡単な説明】
【図１】本発明の排熱回収システムの実施例を示す図である。
【図２】本発明の排熱回収システムの実施例を示す図である。
【図３】図１の排熱回収システムの一部を拡大して示した図である。
【図４】排熱回収システムの制御動作を示すフローチャートである。
【図５】貯湯タンクの蓄熱形態を示す図である。
【図６】メインルーチンにおける弁初期位置の設定処理に関するサブルーチンを示すフローチャートである。
【図７】メインルーチンにおけるエンジン異常停止処理に関するサブルーチンを示すフローチャートである。
【図８】メインルーチンにおけるエンジン運転許可処理に関するサブルーチンを示すフローチャートである。
【図９】メインルーチンにおけるエンジン停止処理に関するサブルーチンを示すフローチャートである。
【図１０】メインルーチンにおけるエンジン強制停止処理に関するサブルーチンを示すフローチャートである。
【図１１】メインルーチンにおける暖房命令処理に関するサブルーチンを示すフローチャートである。
【図１２】メインルーチンにおける給湯積算出力カウンタ処理に関するサブルーチンを示すフローチャートである。
【図１３】メインルーチンにおける弁異常チェック処理に関するサブルーチンを示すフローチャートである。
【図１４】メインルーチンにおける温度センサ異常チェック処理に関するサブルーチンを示すフローチャートである。
【図１５】メインルーチンにおけるエンジン起動処理及び暖機運転処理に関するサブルーチンを示すフローチャートである。
【図１６】メインルーチンにおけるエンジン入温度６５℃制御処理に関するサブルーチンを示すフローチャートである。
【符号の説明】
２ エンジン（熱源）
４ 熱媒（流体）
６ 排熱回収路
８、１０ 温度センサ（温度検出手段）
１６、４５ 循環ポンプ
１７、４７ 直流モータ
２４ 熱交換器
３４ 貯湯タンク（蓄熱手段）
３６ 循環路
３８、４０ バイパス路（遮断手段）
１２４ 制御部（制御手段）[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an exhaust heat recovery system that uses a drive source such as an engine driving a generator as a heat source and recovers and uses the exhaust heat.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a system is known in which a generator is driven by an engine to generate power, and exhaust heat of the engine that is the driving source is recovered and used. The exhaust heat is recovered through a cooling medium and a heat medium as exhaust heat recovery water flowing through the water jacket portion of the engine and through the heat medium. Then, the heat absorption of the heat medium is accumulated, or the heat is used for hot water supply or the like.
[0003]
[Problems to be solved by the invention]
By the way, using a drive source such as an engine as a heat source and circulating a fluid such as a heat medium in the heat source to absorb the exhaust heat means cooling the heat source, and excessive or insufficient cooling is a heat source. There is a possibility that the driving characteristics of a certain driving source are deteriorated, and the driving efficiency is lowered and the durability is impaired.
[0004]
Therefore, the problem to be solved by the present invention is to provide an exhaust heat recovery system that optimizes exhaust heat recovery from a heat source such as an engine, and secondly, recovers exhaust heat to improve efficiency. It is to provide an exhaust heat recovery system that realizes good heat storage, and thirdly to provide an exhaust heat recovery system that reduces heat storage loss during operation of the heat source.
[0005]
[Means for Solving the Problems]
In order to solve the first problem, the exhaust heat recovery system of the present invention circulates a heat source (engine 2) that releases heat and a fluid (heat medium 4) through the heat source, and the exhaust heat from the heat source is An exhaust heat recovery path (6) to be recovered by the fluid, and a pump (circulation pump 16) for circulating the fluid to the heat source through the exhaust heat recovery path; Heat exchange means (heat exchanger 24) for heating water by the heat of the fluid circulating in the exhaust heat recovery path, water before heating in the lower layer of the accumulated warm water, and heat exchange in the upper layer of the warm water The heat storage means for receiving the supply of the warm water heated by the means, storing the heat by the warm water, and extracting the warm water from the upper layer portion (Hot water storage tank 34) And a temperature detection means (temperature sensor 8) for detecting the temperature of the fluid on the inflow side of the heat source, and a value obtained by subtracting the heat storage amount of the heat storage means from the predicted hot water supply demand is equal to or greater than a predetermined heat storage amount. While operating the heat source, according to the detected temperature of the temperature detecting means Control means (control part 124) which controls the number of rotations of a pump and controls the temperature of the fluid on the inflow side of the heat source to a predetermined value is provided.
[0006]
That is, for example, when a fluid such as a heat medium is circulated by a pump operation through an exhaust heat recovery path to a heat source composed of a drive source constituted by an engine or the like, exhaust heat from the heat source is recovered in the fluid. Therefore, if the rotational speed of the pump is controlled, the exhaust heat recovered for the fluid is adjusted, and as a result, the temperature of the fluid on the inflow side of the heat source is controlled. Therefore, exhaust heat recovery from a heat source such as an engine can be optimized, and exhaust heat recovery can be performed efficiently without deteriorating the operation efficiency and durability of the heat source.
[0007]
In the exhaust heat recovery system of the present invention, in order to solve the first problem, in front The heat of the fluid is absorbed by water In the heat exchange means A circulation path (36) for circulating the water, and a pump (circulation pump 45) installed in this circulation path for circulating the water And It is characterized by having. That is, when a fluid such as a heat medium is circulated through the exhaust heat recovery path through the exhaust heat recovery path to the heat source, the exhaust heat from the heat source is recovered in the fluid, but the heat of the fluid is absorbed by water through the heat exchanger. If the pump of the circulation path to be controlled is controlled, the absorption of heat of the fluid by water greatly changes, and as a result, the temperature of the fluid on the inflow side of the heat source is controlled. Therefore, by adjusting the flow rate of the water on the circulation path side through the heat exchanger, the exhaust heat recovery from the heat source such as the engine can be further optimized, and the operating efficiency and the durability of the driving source as the heat source are deteriorated. The exhaust heat can be efficiently recovered without any trouble.
[0008]
In the exhaust heat recovery system of the present invention, the control means controls the number of rotations of the pump, and controls the temperature width of the fluid on the inflow side and the outflow side of the heat source. That is, when the pump rotation speed is controlled, the flow rate of the fluid changes, so that the temperature range of the fluid on the inflow side and the outflow side of the heat source can be controlled, and the operation efficiency and durability of the drive source that is the heat source are reduced. The exhaust heat can be recovered efficiently without deteriorating the temperature.
[0009]
In the exhaust heat recovery system of the present invention, Of the fluid Inflow side and outflow side of the heat source Each A temperature detecting means (temperature sensors 8, 10) for detecting the temperature is provided. That is, it is advantageous to detect the temperature of the fluid on the inflow side of the heat source or the inflow side and the outflow side of the heat source as the control data of the temperature range.
[0010]
In the exhaust heat recovery system of the present invention, the pump is driven by a DC motor (17, 47). That is, an AC motor or a DC motor can be used for driving the pump, but by using a DC motor, the control range of pump rotation can be increased.
[0011]
In the exhaust heat recovery system of the present invention, in order to solve the second problem, The heat storage means is the Water before heating on the lower layer side, Said Accumulate hot water on the upper layer side With From the lower layer side The extracted water is heated by flowing through the heat exchange means, and the hot water obtained by the heat exchange means Pour into the upper layer side Rarely Hot water having different temperatures is accumulated and accumulated stepwise from the upper layer side toward the lower layer side. In other words, if the heat storage by the hot water in the heat storage means is performed by raising the temperature of the upper layer side and lowering the temperature of the lower layer side and laminating and heating up, the hot water can be used from the start of operation of the drive source, which is the heat source. Can be increased.
[0012]
Further, in the exhaust heat recovery system of the present invention, in order to solve the third problem, the exhaust heat recovery system is provided with blocking means (bypass paths 38, 40) provided in the circulation path and blocking the circulation of the water. To do. That is, since the circulation of water is blocked by the blocking means, it is possible to prevent turbulence of the layer temperature due to stacking boiling and the stacked heat storage of the heat storage means, and it is possible to suppress a decrease in utilization efficiency.
[0013]
In the exhaust heat recovery system of the present invention, a drive source for rotating a generator is used as the heat source. That is, the drive source for driving the generator is composed of, for example, an engine, has a considerable amount of exhaust heat, and becomes an effective heat source.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to examples shown in the drawings.
[0015]
1 to 3 show an embodiment of the exhaust heat recovery system of the present invention, FIG. 1 shows an exhaust heat recovery system such as an engine and a hot water storage tank, FIG. 2 shows a heat storage use system such as a heating terminal, and FIG. 1 shows an enlarged portion of the exhaust heat recovery system 1.
[0016]
In this exhaust heat recovery system, an engine 2 as a drive source for driving a generator (not shown) is used as a heat source for releasing heat, and this engine 2 uses engine coolant or exhaust heat recovery as an exhaust heat recovery fluid. An exhaust heat recovery path 6 is formed in which the heat medium 4 as water is circulated and the heat medium 4 recovers the exhaust heat of the engine 2. Temperature sensors 8 and 10 comprising a thermistor or the like are provided as temperature detecting means on the inlet side and the outlet side of the engine 2 of the exhaust heat recovery path 6, respectively, and a bypass path 12 that shuts off the engine 2 side is a three-way valve. 14 is formed. The exhaust heat recovery path 6 includes a circulation pump 16 for forcibly circulating the heat medium 4, a circulation tank 18 that supplies the heat medium 4 to the exhaust heat recovery path 6, and an electric heater that heats the heat medium 4 with power generation output. 20, a flow rate sensor 22, first and second heat exchangers 24, 26, and the like are provided, and a bypass path 28 for shortening the exhaust heat recovery path 6 during warm-up is provided separately from the bypass path 12. It is formed via a three-way valve 30. The circulation pump 16 is driven by a DC motor 17. Note that the temperature sensors 8 and 10 may be composed of only the temperature sensor 8 on the engine inflow side.
[0017]
The heat exchanger 24 is a heating means for hot water 32 using the heat medium 4 as a heat source, and is provided in a circulation path 36 as an exhaust heat recovery path for circulating water to be heated in a hot water storage tank 34 that is a heat storage means. . The circulation path 36 constitutes a closed circuit connecting the bottom surface side and the ceiling side of the hot water storage tank 34, and is provided with bypass paths 38, 40 as blocking means, and with the bypass paths 38, 40. Three-way valves 42 and 44, a heat exchanger 24, a flow rate sensor 43, a circulation pump 45, a temperature sensor 49, and the like are provided as flow path switching means. The circulation pump 45 is driven by a DC motor 47, for example. That is, the hot water 32 heated by the heat exchanger 24 is supplied to the upper layer side of the hot water storage tank 34 in which the stacked boiling is performed. The hot water storage tank 34 is provided with a first buffer plate 46 as a means for preventing turbulent heat accumulation in the hot water 32 supplied and taken out.
[0018]
A water supply channel 48 is provided on the bottom surface side of the hot water storage tank 34, and a drain plug 50 is provided, so that clean water W is supplied from the water supply pipe 52 to the bottom surface side of the hot water storage tank 34. The water supply pipe 52 is provided with a pressure reducing valve 54 and a flow rate sensor 56, and a hot water supply pipe 60 is connected via a mixing valve 58. Further, the hot water storage tank 34 is provided with a second buffer plate 62 as a means for preventing turbulent heat storage due to water supply. A plurality of temperature sensors 641, 642,... 650 are installed at regular intervals on the side surface of the hot water storage tank 34 as temperature detecting means for detecting the temperature of the water that is stacked and heated. In this embodiment, ten temperature sensors 641, 642,... 650 are installed, but fewer or more may be installed depending on the measurement zone.
[0019]
Further, a hot water outlet path 66 is provided on the ceiling side of the hot water storage tank 34, and one end of the hot water outlet path 66 is opened to the outside air via an overpressure relief valve 68 and a negative pressure valve 70, and on the other end side. Are provided with a third heat exchanger 72 for hot-water supply backup, a temperature sensor 74 for detecting the hot water temperature, and the like. The heat exchanger 72 uses the heat of combustion of the fuel gas by the burner 76 as a heat source. The hot water supply pipe 60 on the outlet side of the heat exchanger 72 is provided with the mixing valve 58, the flow rate sensor 78, the water proportional valve 80, the temperature sensor 82 for detecting the mixed temperature, and the like.
[0020]
Moreover, the hot water HW discharged from the hot water supply pipe 60 is supplied to the side of the recirculation circuit 84 and can be poured into the bathtub 86. A three-way valve 88, a circulation pump 90, a water level sensor 92, a temperature sensor 94, a fourth heat exchanger 96, and the like are provided on the side of the circulation path 84 for remedy.
[0021]
Further, the heat exchanger 26 provided in the exhaust heat recovery path 6 is a heating means for hot water 98 as a heating heat medium using the heat medium 4 as a heat source, and is provided in the heating circulation path 100. The heating circulation path 100 is a means for circulating hot water 98 to heating terminals such as the indoor radiator 102 and the bathroom heater / dryer 104, and the hot water tank 106 serves as a means for accumulating the hot water 98 and suppressing expansion boiling. A circulation pump 108, a flow sensor 110, heat exchangers 96 and 112, and the like are provided. A water supply pipe 114 is connected to the hot water tank 106 and a valve 116 for adjusting the water supply is provided. The level sensor 118 is used for level control for storing an appropriate amount of hot water 98 in the hot water tank 106. The heat exchanger 112 uses the combustion heat of the fuel gas from the burner 120 as a heat source, and is used for back-up heating of the hot water 98 as a heating heat source in addition to the reheating of the hot water 122 in the bathtub 86. In the heat exchanger 96, the hot water 122 on the side of the remedy circulation path 84 is heated by the heat of the hot water 98.
[0022]
In this exhaust heat recovery system, the switching direction A, B, C or D of the three-way valve 14, 30, 42, 44 is shown in FIG. 3, for example, during the warm-up operation, the three-way valve 14 is C- The A direction and the three-way valve 30 are switched to the C-A direction. At this time, the three-way valve 42 is switched to the D-A direction and the three-way valve 44 is switched to the DC (closed) direction to prevent natural convection of the hot water 32. It is done.
[0023]
A control unit 124 composed of a computer or the like is installed as a control unit of the exhaust heat recovery system. The control unit 124 includes a CPU as a calculation unit, a ROM and a RAM as storage units, a drive output and detection. An I / O or the like is provided as an output input / output means, and a hot water supply integration output counter 125 is provided as a hot water supply integration means. The control executed by the control unit 124 includes rotation control of the DC motors 17 and 47, open / close control of the three-way valves 42 and 44, and the like. In order to perform such control, detection outputs from various sensors such as the temperature sensors 8 and 10 and the flow rate sensor 22 are added to the control unit 124 as control inputs, and the control output obtained from the control unit 124 is the DC motor 17. And three-way valves 42 and 44, etc., are added to actuators of various control devices. The control unit 124 is provided with a display 126 as a display means for displaying an alarm or the like. The display 126 can be constituted by a character display, a sound generator, or the like. In this embodiment, in order to perform digital control, the control unit 124 using a computer or the like is described as an example. However, a control circuit that performs analog processing may be used.
[0024]
Next, the control operation of this exhaust heat recovery system will be described with reference to the main routine shown in FIG.
[0025]
When the power is turned on, in step S1, various valves such as the three-way valves 14, 30, 42, and 44 are set to initial positions, and then the process proceeds to step S2. In step S2, a constant activation program is executed. This always-start program includes engine abnormal stop control, engine operation permission control, engine stop control, engine forced stop control, heating command control, hot water supply integrated output counter 125 control, valve abnormality check control, temperature sensor abnormality check control, and the like. Is called. In step S3, it is determined whether or not a heating command has been given to the control unit 124. If there is no heating command, the process proceeds to step S4 to determine whether or not engine operation is permitted. That is, it is confirmed by this determination whether it is within the operation permission time set according to the season.
[0026]
When engine operation is permitted in step S4, the process proceeds to step S5, and it is determined whether the required heat storage amount is equal to or greater than a predetermined heat storage amount. That is, in step S5, for example,
(Hot-water supply load × 1.2−integrated output−tank heat storage amount)> 1000 kcal (1)
If the value obtained by subtracting the heat storage amount of the hot water storage tank 34 from the predicted hot water supply demand is equal to or greater than the predetermined heat storage amount, the engine 2 can be operated. In this case, the coefficient 1.2 is an example of a numerical value for giving a margin to the hot water supply load, and is not limited to this numerical value.
[0027]
Here, the “hot water supply load” used for the calculation in step S5 is to determine the expected hot water supply load for each season in advance.
[0028]
[Table 1]

[0029]
That is, the “hot water supply load” is an estimated amount of hot water supply in the next season and time, so for example, when starting CGS operation at 18:00 on July X, the hot water supply load is calculated at 6000 kcal, In addition, when the CGS operation is started at 5:00 on February Y, the hot water supply load is calculated at 2000 kcal.
[0030]
The “integrated output” is the total of the outputs used for hot water supply and pouring obtained using the hot water supply integrated output counter 125 built in the control unit 124. That is, all outputs including backup and heat storage use are obtained in a time zone where there is a demand for hot water supply, and the data is fed back to the engine operation time.
[0031]
Moreover, the calculation of the tank heat storage amount of the hot water storage tank 34 is, for example, a tank capacity of 200 liters, and as shown in FIG. 5, the zones 1 to 7 of the hot water storage tank 34 have the same capacity, and the amount of hot water per zone Is about 28.6 liters. Here, if the water temperature is defined as 5 ° C. in winter, 15 ° C. in spring / autumn, and 25 ° C. in summer, the calorific value Q (kcal) of each zone is
[0032]
Q = 28.6 × {(upper detection temperature + lower detection temperature) / 2−water temperature} (2)
Thus, the tank heat storage amount Qm is the sum of all zones 1 to 7. However, if one condition is {(upper detection temperature + lower detection temperature) / 2−water temperature} <10 ° C., the zone is zero. For example, when the detected temperature of the temperature sensor 641 is 75 ° C. and the detected temperature of the temperature sensor 643 is 70 ° C. in winter, the amount of heat Q in the zone 1 ₁ Is
[0033]
Q ₁ = 28.6 × {(75 + 70) / 2-5} = 1930.5 (kcal) (3)
It becomes. Of the temperature sensors 641 to 650, the temperature sensors 642 and 649 are not used for calculating the heat storage amount Qm.
[0034]
And when it determines with the said required heat storage amount being 1000 kcal or more by step S5, or when the heating command is issued by step S3, it transfers to step S6 and the temperature sensor 650 of the lowest side of the hot water storage tank 34 is shown. It is determined whether the detected temperature is a predetermined temperature, for example, 40 ° C. or higher. If the detected temperature is not higher than the predetermined temperature, the process proceeds to step S7. In step S7, it is determined whether or not a predetermined time, for example, 60 minutes or more has elapsed since the previous stop of the engine 2, and if it is less than the predetermined time, startup of the engine 2 is prohibited to protect the engine. That is, it is confirmed that the hot water temperature on the lowermost side of the hot water storage tank 34 is low, and overheating of the engine 2 is prevented. And when predetermined time has passed, it transfers to step S8, and while starting the engine 2, warm-up operation is performed. In this warm-up operation, the three-way valve 30 is switched to narrow the exhaust heat recovery path 6 via the bypass path 28, and the heat medium temperature rises rapidly.
[0035]
Then, after this warm-up operation, the process proceeds to step S9, and the temperature of the heat medium 4 on the inlet side of the engine 2, that is, the return temperature of the heat medium 4 is controlled to be a predetermined temperature, for example, 65 ° C. This constant temperature control is performed by increasing / decreasing the number of rotations of the DC motor 17 while monitoring the temperature detected by the temperature sensors 8, 10 and increasing / decreasing the flow rate of the heat medium 4 pumped by the circulation pump 16.
[0036]
Next, FIG. 6 shows a subroutine for setting initial valve positions of the three-way valves 14, 30, 42, 44, etc. in step S1 of FIG. That is, when this subroutine starts, in step S101, the three-way valve 42 is in the D-A direction, the three-way valve 44 is in the DC (closed) direction, the three-way valve 30 is in the C-A direction, and the three-way valve 14 is in the C-A direction. Can be switched to. As a result, execution of the always-start program is prepared.
[0037]
Next, FIG. 7 shows engine abnormal stop control which is a subroutine of step S2 of the main routine of FIG. That is, when this subroutine is started, in step S201, it is determined whether or not the operating state of the engine 2 is “operating”. If it is in the operating state, the process proceeds to step S202, and a predetermined time, for example, 10 seconds elapses. After that, the process proceeds to step S203, where it is determined whether or not the gas valve is closed (OFF). If not, the process returns to step S201, and if it is closed, the process proceeds to step S204 to stop the engine. In step S205, an alarm is displayed on the display 126 as a display indicating that the engine has been stopped abnormally.
[0038]
If it is determined in step S201 that the engine 2 is not in an operating state, the process proceeds to step S206, and for example, after a lapse of 10 seconds, the process proceeds to step S207 and the gas valve is open (ON). If it is not open, the process returns to step S201. If it is open, the process proceeds to step S208, the engine is stopped, then the process proceeds to step S209, and the display 126 indicates “Do not stop the engine”. Alarm display is performed.
[0039]
Next, FIG. 8 shows engine operation permission control which is a subroutine of step S2 of the main routine of FIG. That is, when this subroutine is started, it is determined in step S211 whether or not the engine operation is permitted time. If it is in the operation permitted time, the process proceeds to step S212 and "permitted" is output as an engine operation permission instruction. On the other hand, if it is not the engine operation permission time, the process proceeds to step S213, and “prohibited” is output as an instruction to prohibit engine operation permission.
[0040]
Next, FIG. 9 shows engine stop control which is a subroutine of step S2 of the main routine of FIG. That is, when this subroutine starts, in step S215, the power of the engine 2 is turned off, and then the process proceeds to step S216. After the initial valve position control (FIG. 6) is executed, the process proceeds to step S217. Set the operation state to the stop state.
[0041]
Next, FIG. 10 shows engine forced stop control which is a subroutine of step S2 of the main routine of FIG. That is, when this subroutine is started, in step S221, for example, it is determined whether or not the Esc key is pressed as the forced stop input means. When this Esc key is pressed, the process proceeds to step S222, and engine stop control ( 9) is executed, and the control is terminated.
[0042]
Next, FIG. 11 shows heating operation command control which is a subroutine of step S2 of the main routine of FIG. That is, when this subroutine is started, in step S225, it is determined whether or not the terminal switch is turned on as a heating command means on the heating device side or the heating command for bidirectional communication is turned on. The process proceeds to step S226, where the heating command is set to “ON”, and the E-con terminal of the backup intelligent board that is the control means is set to “ON”. Further, in step S227, it is determined whether or not the terminal switch OFF and the two-way communication heating command OFF are established as the heating command means on the heating device side. When the heating stop command is instructed, The process proceeds to S228, where the heating command is set to “OFF”, and the E-con terminal of the backup intelligent board as the control means is set to “OFF”.
[0043]
Next, FIG. 12 shows control of the hot water supply integrated output counter 125, which is a subroutine of step S2 of the main routine of FIG. That is, when this subroutine is started, in step S231, it is determined whether or not the engine operation is “permitted”. If permitted, the process proceeds to step S232 to reset the counter. That is, after setting the amount of heat Qc stored in the hot water supply integrated output counter 125 to 0 kcal, the process proceeds to step S233 to determine the water temperature. That is, after setting 5 ° C. in the winter, 15 ° C. in the spring and autumn, and 25 ° C. in the summer, the process proceeds to step S234, and the hot water temperature of the temperature sensor 82 that is a mixed temperature thermistor is measured.
[0044]
In step S235, the flow rate sensor 78 that detects the amount of hot water supply determines whether, for example, 1 liter is counted as a predetermined flow rate. If 1 liter is counted, the process proceeds to step S236. In step S236, the hot water supply integrated output heat quantity Qc is calculated as the heat quantity calculation per liter. That is, this hot water supply integrated output heat quantity Qc (kcal) is
[0045]
Qc = (hot water temperature-water temperature) × 1 (kcal) (4)
Is calculated by
[0046]
Then, the process proceeds to step S237, where it is determined whether or not the engine operation permission is “prohibited”. When the engine operation is prohibited, the process returns to step S231, and when the engine operation is not prohibited. The process proceeds to step S234, and the processes of step S234 to step S236 are executed.
[0047]
Next, FIG. 13 shows valve abnormality check control which is a subroutine of step S2 of the main routine of FIG. That is, when this subroutine is started, in step S241, it is determined whether or not the valve output and the limit indicating the switching state coincide with each other. If they do not coincide, for example, 30 seconds have passed as a predetermined time in step S242. Thereafter, the process proceeds to step S243, and the display 126 is notified by an alarm that the three-way valves 14, 30, 42, 44, etc. are abnormal. If the valve output and the limit coincide with each other in step S241, the process proceeds to step S244 to output a normal message and display it on the display 126.
[0048]
Next, FIG. 14 shows temperature sensor abnormality check control which is a subroutine of step S2 of the main routine of FIG. That is, when this subroutine is started, in step S251, it is determined whether a disconnection or short circuit abnormality has occurred in the connection line or the like. If an abnormality has occurred, the process proceeds to step S252, and the display 126 displays the temperature. An alarm notifies that the sensors 8, 10, etc. are abnormal. If no abnormality has occurred in step S251, the process proceeds to step S253 to output a normal message and display it on the display 126.
[0049]
Next, FIG. 15 shows control of engine start-up and warm-up operation, which is a subroutine of step S8 of the flowchart shown in FIG.
[0050]
In step S801, in order to prevent the natural convection of the hot water 32, the three-way valve 42 is configured in the DA direction, the three-way valve 44 is configured in the DC direction, and the warm-up circuit is configured. After switching the valve 14 to the CA direction and setting the circulation pump 16 to medium rotation, the process proceeds to step S802 to determine whether the temperature detected by the temperature sensor 10 is a predetermined temperature, for example, 55 ° C. or less. If it exceeds 55 ° C., the process proceeds to step S803, where it is determined whether, for example, 20 minutes have passed as the predetermined time. If 20 minutes have passed after exceeding 55 ° C., it is expected that some abnormality has occurred. Therefore, the process proceeds to step S804, an alarm is generated on the display 126, and “abnormal stop” is notified. To do. At this time, the engine 2 is shifted to the stop mode.
[0051]
If the detected temperature is equal to or lower than the predetermined temperature in step S802, the process proceeds to step S805 and the power supply of the engine 2 is turned on. The process proceeds to step S806 and the engine start contact is turned on for a predetermined time, for example, 5 seconds. Then, after turning off the engine starting contact point, the system waits for a predetermined time, for example, 3 seconds, and proceeds to step S808. In step S808, it is determined whether or not the gas valve is in an ON state. If the gas valve is not in an ON state, the process proceeds to step S809 to determine whether or not the activation is a predetermined number of times, for example, the fifth time. If it is less than or equal to the predetermined number, the process proceeds to step S810, waits for a predetermined time to shift to the predetermined number, for example, 5 seconds, and returns to step S806. If the engine start has reached the predetermined number of times in step S809, the process proceeds to step S811, the engine is stopped, an alarm is generated on the display 126 in step S812, and “engine start failure” is notified. This notification allows the user to know the abnormality.
[0052]
When it is determined in step S808 that the gas valve has been turned ON, the process proceeds to step S813, the engine 2 enters the operating state, and the process proceeds to step S814. In step S814, it is determined whether or not the detected temperature of the temperature sensor 10 exceeds a predetermined temperature, for example, 60 ° C., and if it does not exceed 60 ° C., the process proceeds to step S815 to elapse a predetermined time, for example, 20 minutes. Whether or not has elapsed has been determined, and the transition of the detected temperature is monitored until a predetermined time has elapsed. If the detected temperature does not exceed 60 ° C. even after 20 minutes have elapsed, the process proceeds to step S816, the engine is stopped, and then the process proceeds to step S817 to generate an alarm on the display 126. Announce engine / inverter abnormality. This notification allows the user to know the abnormality.
[0053]
And when the detection temperature of the temperature sensor 10 exceeds 60 degreeC by step S814, it represents that warming-up operation was performed normally, it transfers to step S818, and the three-way valve 30 is switched to a BC direction, After disconnecting the bypass 28, the process returns to step S9 of the main routine (FIG. 4), and the exhaust heat recovery is started together with the power generation by the engine 2.
[0054]
Next, FIG. 16 shows engine input temperature control (control of target value 65 ° C.), which is a subroutine of step S9 of FIG.
[0055]
In step S901, it is always monitored whether or not the engine 2 is in an operating state. That is, the rotation temperature of the circulation pump 45 is controlled by setting the inlet temperature of the heat medium 4 to the engine 2, that is, the return temperature detected by the temperature sensor 8 as a target value, for example, 65 ° C. As a result of this control, when the rotation of the circulation pump 45 is stopped, the three-way valve 44 is switched to the AC (closed) direction, and when the circulation pump 45 is rotating, the three-way valve 44 is set to D. After switching to the -B direction, the process proceeds to step S903.
[0056]
In step S903, it is determined whether the temperature detected by the temperature sensor 650 on the lowermost side of the hot water storage tank 34 is a predetermined temperature, for example, 50 ° C. or higher. If the temperature is not higher than the predetermined temperature, the process proceeds to step S904. In this case, the hysteresis temperature with respect to the starting condition is set to 10 ° C., for example. In step S904, whether or not the temperature at which the heating medium 4 enters the engine 2, that is, the return temperature detected by the temperature sensor 8 is a predetermined temperature, for example, 75 ° C. or more is a predetermined time, for example, 10 seconds or more. And it is determined whether the rotation speed of the circulation pump 45 is the maximum. When the predetermined temperature is equal to or less than the predetermined time and the rotation speed of the circulation pump 45 is not the maximum, the process proceeds to step S905.
[0057]
In step S905, it is determined whether or not the operating state of the engine 2 is stopped. When the engine 2 is not stopped, that is, when it is in the operating state, the process proceeds to step S906 to determine whether or not the heating contact is in the ON state. To do. If it is not ON, the process proceeds to step S907 to determine whether or not the engine operation is permitted. If the engine operation is permitted, the process proceeds to step S908 and the amount of heat stored in the tank becomes (hot water supply load). X1.2-integrated output). That is, this determination is intended to stop the engine operation when this condition is satisfied if the heating is not performed and the engine operation permission time is satisfied.
[0058]
By the way, when the detected temperature of the temperature sensor 650 exceeds a predetermined temperature, that is, 50 ° C. in step S903, or when the predetermined temperature is longer than a predetermined time and the rotation speed of the circulation pump 45 is maximum in step S904. In step S909, the circulation pump 45 is stopped. In step S910, the engine is stopped. In step S911, after waiting for a lapse of a predetermined time from the engine stop, for example, 30 seconds, the process proceeds to step S912, the circulation pump 16 is stopped, and then the process returns to step S2 of the main routine shown in FIG. . That is, the reason why the circulation pump 16 is stopped after the circulation pump 45 is stopped is to prevent collapse of the tiered heat storage on the hot water storage tank 34 side.
[0059]
If the engine 2 is stopped in step S905, the operation of the engine 2 is prohibited in step S907, or if the amount of heat stored in the tank exceeds (hot water supply load × 1.2−integrated output) in step S908, the process proceeds to step S913. Then, the engine is stopped, and after waiting for a predetermined time, for example, 30 seconds, from the engine stop in step S914, the process proceeds to step S915, the circulation pump 45 is stopped, and the process proceeds to step S912.
[0060]
As described above, in this exhaust heat recovery system, the heat medium 4 as the cooling water or the heat recovery water is circulated through the exhaust heat of the engine 2, and the heat exchangers 24 and 26 are provided in the exhaust heat recovery path 6 to heat the exhaust heat. However, it is realized by adjusting the flow rate of the heat medium 4 by controlling the rotation of the circulation pump 16 so that the return temperature of the heat medium 4 becomes a predetermined temperature, for example, 65 ° C. On the other hand, on the side of the circulation path 36 that collects the exhaust heat from the exhaust heat recovery path 6 through the heat exchanger 24 in parallel with the heat medium control, the circulation amount of the hot water 32 is controlled by the rotation control of the circulation pump 45, and the hot water storage The amount of heat stored in the tank 34 is varied. Accordingly, the temperature of the heat medium 4 on the outlet side of the engine 2 includes not only the flow rate control by the circulation pump 16 but also the flow rate control by the circulation pump 45 on the hot water 32 side and the flow rate control by the circulation pump 108 on the heat exchanger 26 side. Therefore, it is possible to control to a desired temperature, that is, a predetermined width by comprehensively controlling these. In this embodiment, the return temperature of the heat medium 4 is controlled to a predetermined value, for example, in a range of 65 ° C. ± 5 ° C., but the return temperature and outlet temperature of the heat medium 4 in the engine 2 are set to a predetermined temperature. The width may be controlled so that the same effect can be obtained even with such control.
[0061]
Although the cooling water return temperature varies depending on the incoming water temperature and the heating load, in order to operate the engine 2 more efficiently and store hot water in the hot water storage tank 34, the circulation flow rate on the exhaust heat recovery side (heat receiving side) must be It is necessary to change the flow rate to be small. Therefore, the exhaust heat recovery path 6 is provided with a circulation pump 16 driven by a DC motor 17 having low power consumption and excellent controllability, so that a wide range of flow control from a small flow rate to a large flow rate is possible. The return temperature of the heat medium 4 with respect to the engine 2 can be controlled efficiently and constantly.
[0062]
In the circulation path 36 serving as an exhaust heat recovery path, the circulation pump 45 is operated as appropriate so that the water taken out from the bottom of the hot water storage tank 34 is sent to the upper side of the hot water storage tank 34, and the heat medium is transferred by the heat exchanger 24. As a result of performing heat exchange with 4, heat storage is performed by stacking boiling from the upper layer side of the hot water storage tank 34. That is, the lowermost water is taken out from the hot water storage tank 34 and heated to become high-temperature water. This high-temperature water is supplied to the upper layer of the hot-water storage tank 34, and the taken-out water is used as the upper layer as high-temperature water. As a result of being supplemented to the part, a hot water layer in which a boundary layer of temperature stands out from the upper layer part side toward the lower layer part is formed, and heat storage is performed. As described above, the hot water storage tank 34 is subjected to high-quality laminated boiling, and as a result, when hot water is requested, the hot water 32, that is, the heat storage, can be taken out from the upper layer of the hot water storage tank 34 and used. Moreover, the hot water 32 can be used from the start of operation. Compared to natural convection type heat storage, there is an advantage that hot water can be used at the start of operation.
[0063]
In addition, two heat exchangers 24 and 26 are installed in the exhaust heat recovery path 6, and when there is a heating request, heat exchange may be performed only with the heat exchanger 26 on the heating side. Heat exchange is also performed on the heat exchanger 24 side. If such heat exchange is left unattended, hot water circulation occurs in the hot water storage tank 34 by natural convection. That is, heat is taken to the heat medium 4 side through the heat exchanger 24, and a reduction in the circulation temperature of heat exchange performed in the heat exchanger 26 is expected. Therefore, in this exhaust heat recovery system, the three-way valves 42 and 44 are installed in the circulation path 36, and the circulation path 36 is controlled to be closed by switching between them, so that natural convection is not generated in the hot water 32 and hot water storage is performed. The heat storage collapse of the tank 34 can be prevented, the temperature of the heat medium 4 can be prevented from lowering during heating operation, the temperature rise during heating can be made sharp, and the heating efficiency can be increased.
[0064]
【The invention's effect】
As described above, according to the present invention, the following effects can be obtained.
a Since the inlet temperature of the fluid circulated to the heat source such as the engine, that is, the return temperature is controlled to a predetermined temperature, the exhaust heat recovery can be optimized and the deterioration of the operating characteristics of the heat source can be prevented. Sex can be maintained. When an engine is used as a drive source that is a heat source, the operation time can be extended and efficient operation can be realized.
b Since the flow rate of water that absorbs the heat of the fluid is controlled in combination with the constant or change of the flow rate of the fluid circulated to the heat source such as the engine, the heat recovery of the heat source can be further optimized, and the operating characteristics of the heat source Can be prevented and its durability can be maintained.
c If the pump is driven by a DC motor, the controllability of the flow rate from a small flow rate to a large flow rate can be improved, and the power consumption can be reduced.
d Stacked water is heated with the recovered exhaust heat, and heat is extracted from the upper layer side as hot water, so that heat can be used at the start of operation, heat loss can be reduced, efficient heat storage can be realized, and exhaust heat can be achieved. Can improve the efficiency of use.
e During operation of the heat source, it is possible to prevent natural convection of hot water stored by stacking and suppressing reduction in heat storage loss and utilization efficiency.
f Since the heat stored from the upper part of the heat storage means is taken out, heat loss can be reduced, heat storage efficiency can be increased, and heat utilization efficiency can be increased.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of an exhaust heat recovery system of the present invention.
FIG. 2 is a diagram showing an embodiment of an exhaust heat recovery system of the present invention.
FIG. 3 is an enlarged view of a part of the exhaust heat recovery system of FIG.
FIG. 4 is a flowchart showing a control operation of the exhaust heat recovery system.
FIG. 5 is a diagram showing a heat storage form of a hot water storage tank.
FIG. 6 is a flowchart showing a subroutine related to a valve initial position setting process in the main routine.
FIG. 7 is a flowchart showing a subroutine related to engine abnormal stop processing in the main routine.
FIG. 8 is a flowchart showing a subroutine related to engine operation permission processing in the main routine.
FIG. 9 is a flowchart showing a subroutine related to engine stop processing in the main routine.
FIG. 10 is a flowchart showing a subroutine related to engine forced stop processing in the main routine.
FIG. 11 is a flowchart showing a subroutine related to a heating command process in the main routine.
FIG. 12 is a flowchart showing a subroutine related to hot water supply integrated output counter processing in the main routine.
FIG. 13 is a flowchart showing a subroutine related to valve abnormality check processing in the main routine.
FIG. 14 is a flowchart showing a subroutine related to temperature sensor abnormality check processing in the main routine.
FIG. 15 is a flowchart showing a subroutine related to engine start-up processing and warm-up operation processing in a main routine.
FIG. 16 is a flowchart showing a subroutine related to an engine input temperature 65 ° C. control process in the main routine.
[Explanation of symbols]
2 Engine (heat source)
4 Heating medium (fluid)
6 Waste heat recovery path
8, 10 Temperature sensor (temperature detection means)
16, 45 Circulation pump
17, 47 DC motor
24 heat exchanger
34 Hot water storage tank (heat storage means)
36 Circuit
38, 40 Bypass (blocking means)
124 control unit (control means)

Claims (8)

A heat source that releases heat,
An exhaust heat recovery path for circulating a fluid to the heat source and recovering the exhaust heat from the heat source to the fluid;
A pump for circulating the fluid to the heat source through the exhaust heat recovery path;
Heat exchange means for heating water by the heat of the fluid circulating in the exhaust heat recovery path;
The stored hot water is stored in the lower layer of the hot water before being heated, and the upper layer of the hot water is supplied with the hot water heated by the heat exchanging means to store heat by the hot water, and the hot water is taken out from the upper layer. Means,
Temperature detecting means for detecting the temperature of the fluid on the inflow side of the heat source;
When the value obtained by subtracting the heat storage amount of the heat storage means from the predicted hot water supply is equal to or greater than a predetermined heat storage amount, the heat source is operated, and the rotational speed of the pump is controlled according to the detected temperature of the temperature detection means , Control means for controlling the temperature of the fluid on the inflow side of the heat source to a predetermined value;
An exhaust heat recovery system comprising: A circulation passage for circulating the water heat of the previous SL fluid to the heat exchange means to be absorbed in water,
A pump installed in this circulation path for circulating the water ;
Exhaust heat recovery system according to claim 1, further comprising a. 3. The exhaust heat recovery system according to claim 1, wherein the control unit controls a temperature range of the fluid on an inflow side and an outflow side of the heat source by controlling a rotation speed of the pump. The exhaust heat recovery system according to claim 3, further comprising temperature detection means for detecting each temperature of the fluid at the inflow side and the outflow side of the heat source.   The exhaust heat recovery system according to claim 1, wherein the pump is driven by a DC motor. The heat storage means, the water before heating the lower portion side, together with the accumulated hot water in the upper portion side, the water taken out from the lower portion side is heated by passing to the heat exchange means, with said heat exchange means Included resulting hot water is poured into the upper portion rare, exhaust heat recovery according to claim 1, wherein the accumulating laminated stepwise different temperatures hot water toward the lower portion from the upper portion system. The exhaust heat recovery system according to claim 2, further comprising a blocking unit that is provided in the circulation path and blocks the circulation of the water. Claim 1 Symbol placement exhaust heat recovery system characterized by using a driving source for rotating the generator to the heat source.

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