JP3617131B2 - Method and apparatus for drying metal strip - Google Patents

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Ｈ_Ｗ ＝Ｈ_ＷＯ−Ｑｔ …（５）
ここで、ρ： 比重、Ｃ：比熱、Ｈ：水膜厚みであり、添字Ｓは鋼帯、Ｗは水膜、ＷＯは乾燥初期の水膜、Ｔ_ＷＯは乾燥初期の水膜温度である
。
【００１３】
また、（２）式及び（４）式より、水膜温度Ｔ_Ｗ は、初期水膜温度Ｔ_ＷＯ、吹付空気の温度Ｔ_Ａ 、熱伝達率αの関数となっていることがわかる。初期水膜温度Ｔ_ＷＯは、乾燥前の水洗で用いる水洗水温度に等しいと考えられ、また熱伝達率αは前記したように空気吹付速度により変更可能である。
従って、水膜表面の空気の絶対湿度ｘ_Ｗ の調整は、水膜温度Ｔ_Ｗ の調整に置き換えが可能であり、水膜温度Ｔ_Ｗ を変更する実機上でのパラメータは、前記（ａ）乾燥前の水洗水温度、（ｂ）吹付空気の温度、（ｃ）吹付空気の速度となる。
３．吹付空気の絶対湿度、ｘ_Ａ
ｘ_Ａ は，例えば空気循環形式の乾燥機を用いると、外気の湿度以上の領域では、循環率を変更することで変更が可能である。また、外気の取入れに際して、除湿器を設置すれば、直接的に変更が可能である。
【００１４】
次に、上記した各制御パラメータを変化させるのに必要なエネルギーを求める。
（１）水洗水の昇温エネルギー、Ｅ_Ｒ
乾燥前の水洗水温度をＴ_Ｒ （℃）、該水洗水の水洗槽取入口での温度をＴ_ＲＯ（℃）、水洗水量をＷ（リッタ／ｍｉｎ）とすると、水洗水をＴ_ＲＯから温度Ｔ_Ｒ に昇温するのに必要なエネルギーＥ_Ｒ は、
Ｅ_Ｒ ＝Ｗ×（Ｔ_Ｒ −Ｔ_ＲＯ） （ｋｃａｌ／ｍｉｎ）
となる。
【００１５】
ここで、水洗水量Ｗは、鋼帯の洗浄に必要な流量であり定数と考えると、Ｔ_ＲＯを測定することで、該エネルギーＥ_Ｒ は、算出可能である。
（２）吹付空気の昇温エネルギー、Ｅ_Ａ
空気用熱交換器前の取入れ空気の温度をＴ_Ａ１（℃）、熱交換後の昇温した空気温度をＴ_Ａ （℃）、風量をＧ（ｍ^３ ／ｍｉｎ）、該空気の比熱をＣ（ｋｃａｌ／ｍ^３ ・℃）とすると、このエネルギーは、
Ｅ_Ａ ＝Ｇ×ｃ×（Ｔ_Ａ −Ｔ_ＡＯ） （ｋｃａｌ／ｍｉｎ）
となる。
【００１６】
ここで、取入れ空気の温度Ｔ_Ａ１は、外気を直接吹付ける形式の乾燥機であれば、外気温度Ｔ_ＡＯに等しいと考えられる。一方、吹付け空気を循環する形式の乾燥機であれば、循環率をβとし、循環戻り空気の温度をＴ_Ａ ’とすると、
Ｔ_Ａ１＝βＴ_Ａ ’＋（１−β）Ｔ_ＡＯ
で与えられる。このＴ_Ａ ’は、実測もしくはＴ_Ａ より熱バランス計算で求めることができるが、いづれにしても外気温度Ｔ_ＡＯを測定することで求めることができる。
（３）空気吹付エネルギー，Ｅ_Ｓ
このエネルギーは、乾燥機のファン動力であり、ファン効率をηとして、
Ｅ_Ｓ ＝（Ｐ×Ｇ）／（η×Ｊ）
で表わされる。
【００１７】
ここで、 Ｐ：空気圧力（ｍｍＡｑ）
Ｊ：熱定数（ｋｇｍ／ｋｃａｌ）
また、吹付風速ｖ_Ａ と圧力の関係は、下記式で求まり、
【００１８】
【数２】

δ：ノズル効率
ｇ：重力加速度
γ：空気の比重
さらに、吹付風量Ｇは、
Ｇ＝Ａ×Ｖ_Ａ
Ａ：ノズル面積
であるので、吹付風速が求まれば、吹付エネルギＥ_Ｓ は容易に求めることができる。
（４）湿度調整に必要なエネルギー、
前記した循環形式の乾燥機において、取入れ外気の湿度調整のため循環率を変化させると、外気取入量も変化し、熱交換器前の空気温度Ｔ_Ａ１が変化する。この変化により変動したエネルギーが、ここでの湿度調整に必要なエネルギーと考えることができる。また、冷凍式除湿器を設置している場合は、この除湿器の運転エネルギーが調湿に必要なエネルギーとなる。
【００１９】
いづれにしても該調湿を行うため及びエネルギー算出のために、取入れ外気の湿度を測定することが必要である。
以上の説明より、高温空気乾燥機での乾燥量は、
（ａ）乾燥前水洗水の温度
（ｂ）吹付空気の温度
（ｃ）吹付空気の湿度
（ｄ）吹付空気の速度
のうち、いずれか１つ以上の調整で可能である。また、それにかかるエネルギーは
ｉ）水洗水取入口
ｉｉ）吹付空気の取入口温度
ｉｉｉ）吹付空気の取入口湿度
を測定することで算出可能である。
【００２０】
したがって、前記（ａ）〜（ｄ）のいずれかを調整可能とし、その設定値をｉ）〜iii)を測定することで決定すれば乾燥に要するエネルギーを最小にした金属帯の完全乾燥が可能である。本発明では、それを５通りの方法で達成するものであり、それらは以下の通りである。
すなわち、本発明は、連続的に薬液処理、水洗した金属帯を、高温空気の吹付けで乾燥するに際して、上記吹付け空気の湿度、温度及び速度を測定もしくは設定すると共に、乾燥前の金属帯表面に付着した水膜厚みを測定若しくは設定し、さらに、これら測定値もしくは設定値、金属帯の板厚、及び水洗水の温度に基づいて算出される乾燥機出口までの水分蒸発量と前記乾燥前の水膜厚みによる水分量が等しくなるよう上記水洗水の温度を決定することを特徴とする金属帯の乾燥方法である。また、本発明は、連続的に薬液処理、水洗した金属帯を、高温空気の吹付けで乾燥するに際して、水洗水の温度、吹付け空気の湿度及び温度を測定もしくは設定すると共に、乾燥前の金属帯表面に付着した水膜厚みを測定もしくは設定し、さらに、これら測定値もしくは設定値、金属帯の板厚、及び吹付け空気の速度に基づいて算出される乾燥機出口までの水分蒸発量と前記乾燥前の水膜厚みによる水分量が等しくなるよう上記吹付け空気の速度を決定することを特徴とする金属帯の乾燥方法であり、吹付け空気の湿度、水洗水の温度及び吹付け空気の速度を測定もしくは設定すると共に、乾燥前の金属帯表面の水膜厚みを測定もしくは設定し、さらに、これら測定値もしくは設定値、金属帯の板厚、及び吹付け空気の温度に基づいて算出される乾燥機出口までの水分蒸発量と前記乾燥前の水膜厚みによる水分量が等しくなるよう上記吹付け空気の温度を決定することを特徴とする金属帯の乾燥方法であり、あるいは水洗水の温度、吹付け空気の温度及び速度を測定もしくは設定すると共に、乾燥前の金属帯表面の水膜厚みを測定もしくは設定し、さらに、これら測定値もしくは設定値、金属帯の板厚、及び吹付空気の湿度に基づいて算出される乾燥機出口までの水分蒸発量と前記乾燥前の水膜厚みによる水分量が等しくなるよう金属帯に上記吹付け空気の湿度を決定することを特徴とする金属帯の乾燥方法である。さらに、本発明は、
（ａ）水洗水の温度
（ｂ）吹付け空気の温度
（ｃ）吹付け空気の湿度
（ｄ）吹付け空気の速度
のうち、いずれか１つ又は２つを測定もしくは設定すると共に、乾燥前の金属帯表面の水膜厚を測定もしくは設定し、さらに、前記（ａ）〜（ｄ）及び金属帯の板厚に基づいて算出される乾燥機出口までの水分蒸発量と前記乾燥前の水膜厚みによる水分量が等しくなり、且つ乾燥エネルギーが最小となるよう残りの３つ又は２つを相互に関連させて決定することを特徴とする金属帯の乾燥方法でもある。
【００２１】
また、これらの方法を実施する装置として、本発明は、薬液処理された金属帯の水洗槽と、該水洗槽に供給する水洗水を昇温する水洗水用熱交換器と、水洗槽から出た金属帯の表面に付着した水を搾るリンガーロールと、通過する該金属帯に高温空気を噴射する複数のノズルを有する乾燥機本体と、外気を取入れる送気ファンと、該取入れた外気を昇温し前記高温空気とする空気用熱交換器とを備えた金属帯の乾燥機において、
上記水洗槽の給水口に水の温度を測定する温度計、
上記リンガーロール出側に金属帯表面の水膜厚みを測定する厚み計、
上記空気用熱交換器出側に高温空気の温度を測定する温度計、
上記ノズル入口に高温空気の湿度を測定する湿度計
を設けると共に、これらの測定値を入力、演算してそれぞれの適正値を求める計算機と、該計算機からの出力を受け水洗水用熱交換器及び空気熱交換器の水蒸気量を変更させる調整手段及び高温空気の流速を変更する調整手段とを備えたことを特徴とする金属帯の乾燥装置である。また、本装置に、上記外気取入口に空気除湿器を追設したり、あるいは上記高温空気の流速を変更する調整手段にＶＶＶＦ制御駆動モータを有する送気ファンを備えるようにした。
【００２２】
その結果、従来に比べてエネルギー消費が少なく、ランニング費用を大幅に低減した金属帯の乾燥が可能になった。
【００２３】
【発明の実施の形態】
（実施形態１）
図１に、本発明に係る金属帯の乾燥方法の１例を示す。
被乾燥体の鋼帯１は、水洗槽５で水洗された後、リンガーロール４により水切りされ、乾燥機６で高温空気の噴射で乾燥される。本発明は、その際、乾燥機６の高温空気取入口に設けた湿度計１６及び空気用熱交換器９の出側に設けた温度計１０により、吹付空気の湿度及び温度が測定される。また、セントラルコンピュータ（Ｃ／Ｃ）１２より，板厚情報がプロセスコンピュータ（Ｐ／Ｃ）１３に与えられ、リンガーロール４出側に設けた水膜厚計１５で水膜厚みが測定される。
【００２４】
そして、以上の情報をプロセスコンピュータ（Ｐ／Ｃ）１３に入力し、そこに記憶されている前記した各式によって乾燥前に行う水洗に用いる水洗水温度を、完全乾燥で且つ乾燥エネルギーが最小になるように決定し、ＴＩＣコントローラ１４’にその値を設定する。その結果、該水洗水温度は、水洗水用熱交換器９’で水蒸気で昇温され、該設定温度に調整される。
【００２５】
なお、吹付空気温度については、本例のように空気昇温機構を持つものであれば、温度計１０の測定値でなく設定値を用いても構わない。また水膜厚計１５を設置していない場合は、水膜厚として仮の値を用いても構わない。
（実施形態２）
図２に、本発明に係る乾燥方法の別の１例を示す。
【００２６】
鋼帯１が水洗槽５で水洗された後、リンガーロール４により水切りされ、乾燥機６の高温空気で乾燥されることは、前記方法と同じである。しかし、本発明では、水洗槽への水取入口に設けた水温計１１で水洗水の温度が、また前記した湿度計１７で吹付空気の湿度が測定される。また、前記方法と同様に、セントラルコンピュータ（Ｃ／Ｃ）１２より，板厚情報がプロセスコンピュータ（Ｐ／Ｃ）１３に与えられ，水膜厚計１６により水膜厚みが測定される。
【００２７】
次に、以上の情報をプロセスコンピュータ（Ｐ／Ｃ）１３に入力し、そこに記憶されている前出の各式を用い、完全乾燥且つ乾燥エネルギーが最小を満足する高温空気の吹付速度を決定し、その値を乾燥機６に設けた空気噴射用のノズルヘッダ７の圧力としてＰＩＣコントローラ１４に設定する。その結果、ＰＩＣコントローラ１４は、送気ファン８の駆動モータ１０の回転数もしくは可変ダンパ１８の開度を変更して、該ノズルヘッダの設定圧力（≒設定風速）になるよう調整される。
【００２８】
なお、水膜計１６を用いずにプロセスコンピュータ（Ｐ／Ｃ）に、水膜厚の設定値を用いても構わない。また、水洗水の温度については、昇温機構が設置されているものは、実測値でなく設定値でも構わない。同様に、吹付空気の湿度についても、調質機構が設置されている場合は実測値でなく設定値でも構わない。
（実施形態３）
図３に、本発明に係る乾燥方法の別の１例を示す。
【００２９】
この方法では、前記同様に、水温計１１により水洗水の温度が、また、湿度計１６により吹付空気の湿度が測定され、さらに、セントラルコンピュータ（Ｃ／Ｃ）１２により板厚情報が与えられる。加えて、水膜厚計１５により水膜厚みが測定され、以上の情報をプロセスコンピュータ（Ｐ／Ｃ）１３に入力して、前記と同様に吹付空気の温度を決定し、それをＴＩＣコントローラ１４に設定する。
【００３０】
その結果、吹付空気の温度は、空気用熱交換器９で水蒸気と熱交換して所定の温度に昇温され、調整される。
なお、水洗水温度については、水洗水の昇温機構を持つものであれば、水温計１１の測定値でなく、設定値を用いても構わない。また、水膜厚計１５を設置していない場合には、水膜厚として仮の値を用いても構わない。
（実施形態４）
図４に、本発明に係る乾燥方法の別の１例を示す。
【００３１】
この例では、水温計１１により水洗水温度が、温度計１０により吹付空気の温度が測定され、セントラルコンピュータ（Ｃ／Ｃ）１２により板厚情報がプロセスコンピュータ（Ｐ／Ｃ）１３に与えられる。また、水膜厚計１５により水膜厚みが測定される。そして、以上の情報をプロセスコンピュータ（Ｐ／Ｃ）１３に入力し、前記と同様にして吹付空気の湿度を決定し、それを湿度コントローラ（ＸＩＣ）１７に設定する。
【００３２】
その結果、外気取入ダンパ１８が調整され、外気取入口１９より外気が取り入れられ、ノズルヘッダ７における吹付空気の湿度が調整される。ところで、外気湿度が高く、可変ダンパー１８を全開にしても目標湿度とならない場合は、除湿器２０を運転することで該空気の湿度を制御する。
なお、水洗水温度については、昇温機構を持つものであれば実測値を用いなくとも設定値で構わない。また、水膜厚計１５を設置していない場合は水膜厚として仮の値を用いても構わないものとする。
（実施形態５）
図５に、本発明に係る５番目の乾燥方法を示す。
【００３３】
本発明では、水洗槽５の水洗水は水洗水用熱交換器９’により温度調整が可能であり、水温計１１’により水洗槽への取入時の水温が測定される。また、乾燥機６で鋼帯１に吹きつける高温空気は、空気用熱交換器９でその温度を調整することが可能であり、送気ファン８の駆動モータ２３のＶＶＶＦ制御により吹付空気の速度（ファン吐出圧力）を調整可能としている。さらに、可変ダンパ１８により高温空気の循環率を、あるいは除湿器２０により高温空気の湿度を調整可能とし、温度計１０’及び湿度計１６’により、取入外気の温度及び湿度を測定できる。
【００３４】
実施手順としては、水温計１１、空気の温度計１０及び湿度計１６’で測定した水洗水及び高温空気取入時の水温、空気の温度及び湿度が、まずプロセスコンユータ（Ｐ／Ｃ）１３に取り込まれる。また、セントラルコンピュータ（Ｃ／Ｃ）１２により板厚が，水膜厚計１５から水膜情報が，同様にプロセスコンピュータ（Ｐ／Ｃ）１３に組み込まれる。そして、該プロセスコンピュータ（Ｐ／Ｃ）１３は、以上の情報を用いて鋼帯１を最小の乾燥エネルギ（コスト）で且つ完全に乾燥させるのに必要な水洗水温、吹付空気の温度、湿度、風速を算出し、それぞれのコントローラ１４、１４’１７、２２に設定値として出力する。次に、各々のコントローラ１４、１４’、１７、２２は、水洗水温、吹付空気の温度、湿度及び速度（風圧）を上記設定値となるように調整し、鋼帯１を乾燥する。
【００３５】
なお、水膜厚計１５のない場合は設定値でもかまわない。また以上の全ての制御がなくても少なくとも２つ以上あれば、その範囲で最適計算を行い、設定するものとする。
【００３６】
【発明の効果】
以上述べたように、本発明により、金属帯の高温空気噴射による完全乾燥をエネルギー最小で行うことが可能となった。
【図面の簡単な説明】
【図１】本発明に係る金属帯の乾燥方法の１実施形態を示す図である。
【図２】本発明に係る金属帯の乾燥方法の１実施形態を示す図である。
【図３】本発明に係る金属帯の乾燥方法の１実施形態を示す図である。
【図４】本発明に係る金属帯の乾燥方法の１実施形態を示す図である。
【図５】本発明に係る金属帯の乾燥方法の１実施形態を示す図である。
【図６】従来の金属帯の乾燥方法を説明する図である。
【図７】本発明に係る金属帯の乾燥方法で用いる制御概念を示す図である。
【符号の説明】
１ 金属帯（鋼帯）
２ 薬液槽
３ 薬液
４ リンガーロール
５ 水洗槽
６ 乾燥機
７ ノズルヘッダ
８ 送気ファン
９ 空気用熱交換器（９’ 水洗水用）
１０ 空気の温度計
１１ 水温計
１２ セントラルコンピュータ（Ｃ／Ｃ）
１３ プロセスコンピュータ（Ｐ／Ｃ）
１４ 温度コントローラ（ＴＩＣ）
１５ 水膜厚計
１６ 湿度計
１７ 湿度コントローラ
１８ 可変ダンパ
１９ 空気取入口
２０ 除湿器
２１ 圧力計
２２ 圧力コントローラ（ＰＩＣ）
２３ 可変速モータ（ＶＶＶＦ）[0001]
[Industrial application fields]
The present invention relates to a method for drying a metal strip, and more particularly, to a method for drying a metal strip that has been subjected to chemical treatment on-line continuously by washing with water and hot air jet and an apparatus used for the method.
[0002]
[Prior art]
In continuous production of a steel strip, the steel strip is subjected to heat treatment such as annealing and pickling, or chemical treatment on-line. An example of the general chemical solution treatment step is shown in FIG. 6. First, the steel strip 1 is immersed in the chemical solution 3 in the chemical solution tank 2, and the chemical solution 3 is squeezed out with the ringer roll 4. And then drained again with the Ringer roll 4. However, since the steel strip 1 still has a portion where a water film is left on the surface, there is a serious problem that rust is generated if the state is maintained. Sent to the process. The dryer 6 used there usually takes outside air with a fan 8, raises the temperature with a heat exchanger 9, and blows it from the air jet header 7 onto the steel strip 1 at high speed.
[0003]
However, the conventional drying method described above often employs an operation method in which the temperature and blowing speed of the air blown from the air jet header 7 of the dryer 6 are always constant, and these values are Virtually the most difficult condition of the metal strip was set excessively. For example, Japanese Examined Patent Publication No. 59-38286 states, “In the method of cooling a metal strip from a continuous annealing furnace, a device for water-cooling the metal strip on the exit side of the annealing furnace and spraying heated air on the metal strip after water cooling. A drying device is provided to pass through the metal band, and the metal band temperature on the inlet side and the outlet side of the drying device is measured, and the metal band temperature on the drying device outlet side is the metal band temperature on the drying device inlet side or the atmosphere. The metal strip cooling method is characterized in that the heating temperature and / or flow rate of the drying air is controlled to be 5 ° C. or more higher than the higher one of the wet bulb temperatures. However, this conventional method is not necessarily optimized for drying, and there is a problem that the motive energy of the fan 8 and the air heating energy consumed by the heat exchanger 9 are wasteful.
[0004]
Further, from the viewpoint of saving energy required for drying, there is a recycling technique for drying exhaust air disclosed in many publications in addition to Japanese Patent Laid-Open No. 58-19490. However, these techniques are not sufficient in terms of optimum drying, and energy waste has not been completely eliminated.
[0005]
[Problems to be solved by the invention]
In view of such circumstances, an object of the present invention is to provide a method and an apparatus for drying a metal strip that consumes less energy than the prior art and can significantly reduce running costs.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the inventor conducted research on a method for completely removing the water film on the surface of the metal strip with a minimum energy as follows.
That is, in the drying of an object by high-temperature air spraying, the relationship of formula (1) is generally established.
[0007]
_{Q = k (x W -x A} ) ... (1)
Q: Evaporated water content per unit area and time (kg / m ² · hr)
k: Mass transfer coefficient (kg / m ² · hr)
x _A : absolute humidity of the blowing air (weight ratio of water and air)
x _w : Expressed by the saturated absolute humidity of air on the object surface. The mass transfer coefficient k is known to be proportional to the heat transfer coefficient α (kcal / m ² · hr ° C.) due to the similarity between mass transfer and heat transfer in turbulent flow.
[0008]
Here, x _W is a numerical value determined in relation to the object to be dried, if the object is a steel plate, size and moving speed of the plate, depending on the thickness and the surface temperature of the water film. However, since the size of the equipment is determined by drying with high-temperature air and it is necessary to dry within a certain time, the dimensions and moving speed of the plate are constant. The optimum drying referred to in the present specification means that the above-mentioned Q is minimized and the energy is not excessively deficient.
[0009]
Therefore, the present invention is to provide a method and an apparatus for constantly maintaining the Q in the formula (1) optimally in the drying, and for this purpose, based on the formula (1), k, x _W , x _A Obviously, the three parameters may be adjusted appropriately. In the present invention, each of the parameters can be adjusted, and some are set to be constant, and various combinations of k, x _W , and x _A necessary for obtaining an optimum drying amount Q are considered. However, parameters to be changed in an actual device to adjust k, x _W , x _A, etc. are as follows:
(A) Washing water temperature before drying (b) Temperature of blowing air (c) Humidity of blowing air (d) Speed of blowing air was selected. FIG. 7 shows an adjustment concept used in the method for drying a metal strip according to the present invention.
[0010]
Hereinafter, each parameter will be described.
1. Mass transfer coefficient, k
As described above, k is considered to be proportional to the heat transfer coefficient α due to the similarity between mass transfer and heat transfer in turbulent flow. Since it is known that the heat transfer coefficient α is generally determined by the shape and blowing speed of the nozzle that blows air, it can be seen that k can be changed by the blowing speed of air.
2. Absolute humidity of air on the surface of the water film, x _W
x _W is determined by the water film temperature of the steel strip surface is dry. Even if it is assumed that the temperature of the water film attached to the steel strip is equal to the temperature of the steel strip, there is no significant error, so the heat balance during drying is expressed by equations (2) and (3).
[0011]
_{E 1 = α (T A -T} W) ... (2)
E ₂ = Q · G (3)
E ₁ : Unit area from blowing air, heat transfer amount per unit time T _A : Blowing air temperature T _W : Water film temperature ≈ steel strip temperature E ₂ : Unit area due to latent heat of evaporation, heat removal amount per hour G: latent heat of evaporation α: follow the heat transfer coefficient, water film temperature (≒ steel strip temperature) T _W is represented by formula (4), MizumakuAtsu H _w is expressed by equation (5).
[0012]
[Expression 1]

H _W = H _WO −Qt (5)
Here, ρ: specific gravity, C: specific heat, H: water film thickness, subscript S is a steel strip, W is a water film, WO is a water film at the initial drying stage, and T _WO is a water film temperature at the initial drying _stage .
[0013]
Further, (2) from the equation, and (4), water film temperature T _W is seen to have become initial water film temperature T _WO, the temperature T _A of the blowing _air, as a function of the heat transfer coefficient alpha. The initial water film temperature _TWO is considered to be equal to the washing water temperature used in the washing before drying, and the heat transfer coefficient α can be changed by the air blowing speed as described above.
Therefore, adjustment of the absolute humidity x _W air water film surface is capable of replacing the adjustment of the water film temperature T _W, the parameters on the actual changing the water film temperature T _W, the (a) dry The previous washing water temperature, (b) the temperature of the blowing air, and (c) the velocity of the blowing air.
3. Absolute humidity of blowing air, x _A
x _A, for example the use of drier air circulation type, in the outside air humidity or more regions, but may be modified by changing the circulation rate. Moreover, when taking in outside air, if a dehumidifier is installed, it can change directly.
[0014]
Next, the energy required to change each control parameter described above is obtained.
(1) Temperature rise energy for flush water, E _R
The washing water temperature before drying _{T R (℃), T RO} (℃) the temperature at inlet water washing tank of water washing water and the washing water and W (liter / min), the temperature washing water from _{T RO} energy _{E R} needed to heated to T _R is,
E _R = W × (T _R −T _RO ) (kcal / min)
It becomes.
[0015]
Here, washing water W, given a is constant flow rate required for cleaning of the steel strip, by measuring the T _RO, the energy E _R can be calculated.
(2) Temperature rise energy of blowing air, E _A
The temperature of the intake air before the heat exchanger for air is T _A1 (° C.), the temperature of the heated air after heat exchange is T _A (° C.), the air volume is G (m ³ / min), and the specific heat of the air is C (Kcal / m ³ · ° C), this energy is
_{E A = G × c × (} T A -T AO) (kcal / min)
It becomes.
[0016]
Here, the temperature T _A1 of the intake air is considered to be equal to the outside air temperature T _AO if the dryer is of a type that directly blows outside air. On the other hand, in the case of a dryer that circulates blowing air, if the circulation rate is β and the temperature of the circulating return air is T _A ′,
T _A1 = βT _A '+ (1-β) T _AO
Given in. This T _A ′ can be obtained by actual measurement or heat balance calculation from T _A, but in any case, it can be obtained by measuring the outside air temperature T _AO .
(3) air-blowing energy, _{E S}
This energy is the fan power of the dryer.
E _S = (P × G) / (η × J)
It is represented by
[0017]
Where P: Air pressure (mmAq)
J: Thermal constant (kgm / kcal)
Further, the relationship between the blowing wind speed v _A and the pressure is obtained by the following equation:
[0018]
[Expression 2]

δ: nozzle efficiency g: acceleration of gravity γ: specific gravity of air
G = A × V _A
A: Since the nozzle area, if Motomare is blowing wind, blowing energy E _S can be easily obtained.
(4) Energy required for humidity adjustment,
In dryer circular fashion described above, varying the circulation rate for the humidity control of the intake fresh air, outdoor air Iriryou also changes, the heat exchanger before the air temperature T _A1 changes. The energy that fluctuates due to this change can be considered as the energy necessary for humidity adjustment here. Further, when a refrigeration dehumidifier is installed, the operating energy of the dehumidifier is energy required for humidity control.
[0019]
In any case, it is necessary to measure the humidity of the intake outside air in order to adjust the humidity and calculate the energy.
From the above explanation, the drying amount in the high-temperature air dryer is
It is possible by adjusting any one or more of (a) temperature of washing water before drying (b) temperature of blowing air (c) humidity of blowing air (d) speed of blowing air. Moreover, the energy concerning it can be calculated by measuring i) the flush water intake port ii) the intake air temperature of the blowing air iii) the intake air humidity of the blowing air.
[0020]
Therefore, if any of the above (a) to (d) can be adjusted and the set value is determined by measuring i) to iii), the metal band can be completely dried with the minimum energy required for drying. It is. In the present invention, this is achieved by five methods, which are as follows.
That is, the present invention is continuously chemical treatment, water washing metal strip, when dried in only blowing hot air, the spraying air humidity, together with the measured or set temperature and speed, before drying the metal strip the water film thickness deposited on the surface was measured or set, in addition, these measurements or setting value, the amount of moisture evaporation until the dryer outlet that is calculated based on the temperature of the plate thickness, and washing water of the metal strip the The metal strip drying method is characterized in that the temperature of the washing water is determined so that the amount of water depending on the thickness of the water film before drying becomes equal . Further, the present invention is continuously chemical treatment, water washing metal strip, when dried in only blowing hot air, the temperature of washing water, measuring or sets the humidity and temperature of the spraying air, before drying the MizumakuAtsu only adhered to the metal strip surface is measured or set, in addition, these measurements or set values, moisture up to the dryer outlet thickness of the metal strip, and that is calculated based on the speed of the blast air a method of drying the metal strip, characterized in that the water content due to water film thickness before the drying and the evaporation amount is determined the speed of the blast air to be equal, spraying air humidity, the temperature of washing water and Measure or set the speed of the blowing air, measure or set the water film thickness on the surface of the metal strip before drying, and further measure or set the measured value or set value, the thickness of the metal strip , and the temperature of the blowing air. is calculated have based Dzu That the dryer is a dry method of metal strip and determining the spraying temperature of the air so that the moisture content be equal due to the moisture evaporation amount and the pre-drying of the water film thickness to the outlet, or the washing water Measure or set the temperature , the temperature and speed of the blowing air, and measure or set the water film thickness on the surface of the metal strip before drying. In addition, these measured values or set values, the thickness of the metal strip , and the blowing air metal characterized by determining the spraying air humidity to the metal strip so that the moisture content be equal due to the moisture evaporation amount and the pre-drying of the water film thickness up to the dryer outlet that is calculated based on the humidity This is a method for drying the belt. Furthermore, the present invention provides
(A) Washing water temperature (b) Temperature of sprayed air (c) Humidity of sprayed air (d) One or two of the speeds of sprayed air are measured or set and before drying the metal strip surface a water film thickness is measured or set, further wherein (a) ~ (d) and before the dryer outlet that is calculated based on the thickness of the metal strip moisture evaporation amount and the pre-drying of the It is also a method for drying a metal strip, wherein the remaining three or two are determined in relation to each other so that the amount of water by the water film thickness is equal and the drying energy is minimized.
[0021]
Further, as an apparatus for carrying out these methods, the present invention includes a washing tank of a metal strip that has been treated with a chemical solution, a heat exchanger for washing water that raises the temperature of washing water supplied to the washing tank, and a washing tank. A ringer roll that squeezes water adhering to the surface of the metal strip, a dryer main body having a plurality of nozzles for injecting high-temperature air to the metal strip passing therethrough, an air supply fan for taking in outside air, and the outside air that has been taken in In a metal strip dryer equipped with a heat exchanger for air that is heated to the high temperature air,
A thermometer for measuring the temperature of water at the water supply port of the washing tank,
A thickness meter that measures the water film thickness on the metal strip surface on the ringer roll exit side,
A thermometer for measuring the temperature of hot air on the outlet side of the air heat exchanger,
A hygrometer that measures the humidity of high-temperature air is provided at the nozzle inlet, a computer for inputting and calculating these measured values to obtain respective appropriate values, a heat exchanger for washing water that receives the output from the computer, and An apparatus for drying a metal strip, comprising: an adjusting means for changing a water vapor amount of an air heat exchanger; and an adjusting means for changing a flow rate of high-temperature air. In addition, an air dehumidifier is additionally installed in the outside air inlet or an air supply fan having a VVVF control drive motor is provided in the adjusting means for changing the flow velocity of the high-temperature air.
[0022]
As a result, it has become possible to dry a metal strip that consumes less energy than before and has greatly reduced running costs.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
(Embodiment 1)
FIG. 1 shows an example of a method for drying a metal strip according to the present invention.
The steel strip 1 to be dried is washed in a water rinsing tank 5, drained by a ringer roll 4, and dried by spraying high-temperature air in a dryer 6. In the present invention, the humidity and temperature of the blowing air are measured by the hygrometer 16 provided at the high temperature air intake port of the dryer 6 and the thermometer 10 provided on the outlet side of the air heat exchanger 9. Further, the central computer (C / C) 12 gives plate thickness information to the process computer (P / C) 13, and the water film thickness is measured by a water film thickness meter 15 provided on the exit side of the ringer roll 4.
[0024]
Then, the above information is input to the process computer (P / C) 13, and the washing water temperature used for washing before drying by the above-described formulas is completely dried and the drying energy is minimized. And the value is set in the TIC controller 14 ′. As a result, the washing water temperature is raised with steam in the washing water heat exchanger 9 'and adjusted to the set temperature.
[0025]
In addition, about a blowing air temperature, as long as it has an air temperature rising mechanism like this example, you may use a set value instead of the measured value of the thermometer 10. FIG. Further, when the water film thickness meter 15 is not installed, a temporary value may be used as the water film thickness.
(Embodiment 2)
FIG. 2 shows another example of the drying method according to the present invention.
[0026]
After the steel strip 1 is washed in the washing tank 5, it is drained by the ringer roll 4 and dried by the high-temperature air of the dryer 6 as in the above method. However, in the present invention, the temperature of the flush water is measured by the water temperature gauge 11 provided at the water intake port to the flush tank, and the humidity of the blowing air is measured by the hygrometer 17 described above. Similarly to the above method, the central computer (C / C) 12 gives plate thickness information to the process computer (P / C) 13, and the water film thickness meter 16 measures the water film thickness.
[0027]
Next, the above information is input to the process computer (P / C) 13 and the above-mentioned equations stored therein are used to determine the spray speed of high-temperature air that is completely dry and that satisfies the minimum drying energy. Then, the value is set in the PIC controller 14 as the pressure of the nozzle header 7 for air injection provided in the dryer 6. As a result, the PIC controller 14 changes the rotational speed of the drive motor 10 of the air supply fan 8 or the opening degree of the variable damper 18 to adjust the nozzle header to the set pressure (≈set wind speed).
[0028]
The set value of the water film thickness may be used in the process computer (P / C) without using the water film meter 16. Moreover, about the temperature of flush water, what is provided with the temperature rising mechanism may be not a measured value but a set value. Similarly, the humidity of the blowing air may be a set value instead of an actual measurement value when a tempering mechanism is installed.
(Embodiment 3)
FIG. 3 shows another example of the drying method according to the present invention.
[0029]
In this method, the temperature of the washing water is measured by the water thermometer 11, the humidity of the blowing air is measured by the hygrometer 16, and the thickness information is given by the central computer (C / C) 12. In addition, the water film thickness is measured by the water film thickness meter 15, and the above information is input to the process computer (P / C) 13 to determine the temperature of the blown air in the same manner as described above. Set to.
[0030]
As a result, the temperature of the blowing air is adjusted by raising the temperature to a predetermined temperature by exchanging heat with water vapor in the air heat exchanger 9.
As for the washing water temperature, a set value may be used instead of the measurement value of the water thermometer 11 as long as it has a washing water temperature raising mechanism. Moreover, when the water film thickness meter 15 is not installed, a temporary value may be used as the water film thickness.
(Embodiment 4)
FIG. 4 shows another example of the drying method according to the present invention.
[0031]
In this example, the washing water temperature is measured by the water thermometer 11, the temperature of the blowing air is measured by the thermometer 10, and the plate thickness information is given to the process computer (P / C) 13 by the central computer (C / C) 12. Further, the water film thickness is measured by the water film thickness meter 15. Then, the above information is input to the process computer (P / C) 13, the humidity of the blowing air is determined in the same manner as described above, and it is set in the humidity controller (XIC) 17.
[0032]
As a result, the outside air intake damper 18 is adjusted, outside air is taken in from the outside air inlet 19, and the humidity of the blowing air in the nozzle header 7 is adjusted. By the way, when the outside air humidity is high and the target humidity is not reached even when the variable damper 18 is fully opened, the humidity of the air is controlled by operating the dehumidifier 20.
The washing water temperature may be a set value without using the actual measurement value as long as it has a temperature raising mechanism. Moreover, when the water film thickness meter 15 is not installed, a temporary value may be used as the water film thickness.
(Embodiment 5)
FIG. 5 shows a fifth drying method according to the present invention.
[0033]
In the present invention, the temperature of the rinsing water in the rinsing tank 5 can be adjusted by the rinsing water heat exchanger 9 ', and the water temperature when taken into the rinsing tank is measured by the water temperature gauge 11'. The temperature of the high-temperature air blown to the steel strip 1 by the dryer 6 can be adjusted by the air heat exchanger 9, and the speed of the blown air is controlled by the VVVF control of the drive motor 23 of the air supply fan 8. (Fan discharge pressure) can be adjusted. Furthermore, the variable damper 18 can adjust the circulation rate of the high-temperature air, or the dehumidifier 20 can adjust the humidity of the high-temperature air, and the temperature and humidity of the intake outside air can be measured by the thermometer 10 ′ and the hygrometer 16 ′.
[0034]
As an implementation procedure, the water temperature, air temperature and humidity at the time of taking in the washing water and high-temperature air measured by the water thermometer 11, the air thermometer 10 and the hygrometer 16 ′ are first a process computer (P / C) 13. Is taken in. Further, the central computer (C / C) 12 incorporates the plate thickness, and the water film thickness meter 15 also incorporates the water film information into the process computer (P / C) 13. Then, the process computer (P / C) 13 uses the above-mentioned information to wash the steel strip 1 with the minimum drying energy (cost) and completely dry the washing water temperature, the temperature of the blowing air, the humidity, The wind speed is calculated and output as a set value to each of the controllers 14, 14 ′ 17 and 22. Next, each controller 14, 14 ′, 17, 22 adjusts the washing water temperature, the temperature of the blowing air, the humidity, and the speed (wind pressure) to the above set values, and dries the steel strip 1.
[0035]
In the case where the water film thickness meter 15 is not provided, a set value may be used. Further, even if there is not all the above control, if there are at least two or more, the optimum calculation is performed and set within that range.
[0036]
【The invention's effect】
As described above, according to the present invention, it is possible to perform complete drying of a metal strip by high-temperature air injection with minimum energy.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of a method for drying a metal strip according to the present invention.
FIG. 2 is a diagram showing an embodiment of a method for drying a metal strip according to the present invention.
FIG. 3 is a view showing an embodiment of a method for drying a metal strip according to the present invention.
FIG. 4 is a diagram showing an embodiment of a method for drying a metal strip according to the present invention.
FIG. 5 is a diagram showing an embodiment of a method for drying a metal strip according to the present invention.
FIG. 6 is a diagram for explaining a conventional method for drying a metal strip.
FIG. 7 is a diagram showing a control concept used in the metal strip drying method according to the present invention.
[Explanation of symbols]
1 Metal strip (steel strip)
2 Chemical solution tank 3 Chemical solution 4 Ringer roll 5 Flushing tub 6 Dryer 7 Nozzle header 8 Air supply fan 9 Air heat exchanger (for 9 'flush water)
10 Air Thermometer 11 Water Thermometer 12 Central Computer (C / C)
13 Process computer (P / C)
14 Temperature controller (TIC)
15 Water thickness meter 16 Hygrometer 17 Humidity controller 18 Variable damper 19 Air intake 20 Dehumidifier 21 Pressure gauge 22 Pressure controller (PIC)
23 Variable speed motor (VVVF)

Claims (8)

Continuously chemical treatment, water washing metal strip, when dried in only blowing hot air,
Measure or set the humidity , temperature and speed of the blowing air, measure or set the thickness of the water film attached to the surface of the metal strip before drying, and further, these measured values or set values, the thickness of the metal strip , and the metal strip, characterized in that the moisture content due to moisture evaporation and the pre-drying of the water film thickness up to the dryer outlet that is calculated based on the temperature of washing water to determine the temperature of the washing water to be equal Drying method. Continuously chemical treatment, water washing metal strip, when dried in only blowing hot air,
The temperature of washing water, the measured or set the humidity and temperature of the spraying air, MizumakuAtsu only adhering to the metal strip surface before drying was measured or set, In addition, these measurements or settings of the metal strip thickness, and determining the speed of the blast air so that the moisture content be equal by the water film thickness before the drying and water evaporation amount until the dryer outlet that is calculated based on the speed of the blast air A method of drying a metal strip characterized. Continuously chemical treatment, water washing metal strip, when dried in only blowing hot air,
Humidity of spraying air, as well as measuring or setting the speed of the temperature and blowing air of the washing water, the water film thickness of the metal strip surface before drying was measured or set, In addition, these measurements or setting value, the metal strip the thickness, and determining the temperature of the spraying air so that the moisture content be equal by spraying water evaporation and the pre-drying of the water film thickness up to the dryer outlet that is calculated based on the temperature of the air A metal band drying method characterized by the above. Continuously chemical treatment, water washing metal strip, when dried in only blowing hot air,
Measure or set the temperature of washing water, the temperature and speed of blowing air, measure or set the water film thickness on the surface of the metal strip before drying, and further, these measured values or set values, the thickness of the metal strip , and characterized by determining the humidity of the spraying air to the metal strip so that the moisture content due to moisture evaporation and the pre-drying of the water film thickness up to the dryer outlet that is calculated based on the humidity of the blowing air is equal A method for drying a metal strip. Continuously chemical treatment, water washing metal strip, when dried in only blowing hot air,
(A) Washing water temperature (b) Temperature of sprayed air (c) Humidity of sprayed air (d) One or two of the speeds of sprayed air are measured or set and before drying the metal strip surface a water film thickness is measured or set, further wherein (a) ~ (d) and before the dryer outlet that is calculated based on the thickness of the metal strip moisture evaporation amount and the pre-drying of the A method for drying a metal strip, characterized in that the remaining three or two are determined in relation to each other so that the amount of water depending on the water film thickness is equal and the drying energy is minimized. A washing tank of a metal strip that has been subjected to chemical treatment, a heat exchanger for washing water that raises the temperature of the washing water supplied to the washing tank, a ringer roll that squeezes water attached to the surface of the metal strip that has come out of the washing tank, A dryer body having a plurality of nozzles for injecting high-temperature air to the metal strip passing therethrough, an air supply fan for taking in the outside air, and an air heat exchanger for raising the temperature of the taken-in outside air to the high-temperature air. In the provided metal strip dryer,
A thermometer for measuring the temperature of water at the water supply port of the washing tank,
A thickness meter that measures the water film thickness on the metal strip surface on the ringer roll exit side,
A thermometer for measuring the temperature of hot air on the outlet side of the air heat exchanger,
While providing a hygrometer for measuring the humidity of high-temperature air at the nozzle inlet,
A calculator that inputs and calculates these measured values to obtain the appropriate values for each,
An apparatus for drying a metal strip, comprising: an adjustment means for changing the water vapor amount of the washing water heat exchanger and the air heat exchanger and an adjustment means for changing the flow rate of the high-temperature air in response to the output from the computer . The metal strip drying apparatus according to claim 6, wherein an air dehumidifier is additionally provided at the outside air inlet. 7. The metal strip drying apparatus according to claim 6, wherein the adjusting means for changing the flow velocity of the high-temperature air includes an air supply fan having a VVVF control drive motor.

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