JP2004361059A

JP2004361059A - Exhaust gas outlet temperature control method and device for temperature reducing tower

Info

Publication number: JP2004361059A
Application number: JP2003163458A
Authority: JP
Inventors: Yasuo Tsuruya; 康雄鶴屋
Original assignee: IHI Corp
Current assignee: IHI Corp
Priority date: 2003-06-09
Filing date: 2003-06-09
Publication date: 2004-12-24
Anticipated expiration: 2023-06-09
Also published as: JP4093121B2

Abstract

<P>PROBLEM TO BE SOLVED: To accurately adjust an exhaust gas temperature of a temperature reducing tower outlet to a set temperature without humidifying dust in exhaust gas. <P>SOLUTION: The gas outlet temperature control device for the temperature reducing tower is provided with injection nozzles arranged in two tiers with a predetermined interval in a flowing direction in a gas inlet side of the temperature reducing tower leading exhaust gas in from a gas inlet and leading the exhaust gas from a gas outlet, flow regulating valves respectively provided in the injection nozzles, a temperature detector installed in the gas outlet, and a controller inputted with a detected temperature 17 of the temperature detector, adjusting an opening of one flow regulating valve on the basis of change of an average value T<SB>1</SB>of the detected temperature 17 of the temperature detector within a narrow width detection time S<SB>1</SB>set at a short time interval, and adjusting an opening of the other flow regulating valve on the basis of change of an average value T<SB>2</SB>of the detected temperature 17 within a wide width detection time S<SB>2</SB>set at a long interval. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、ごみ処理施設やセメントプラント等の燃焼炉を有する燃焼設備において、排ガスを所要の設定温度まで減温させるために用いられる減温塔の排ガス出口温度制御方法及び装置に関するものである。
【０００２】
【従来の技術】
ごみ処理施設やセメントプラント等の燃焼炉を有する燃焼設備において、ダストを含んだ排ガスの温度を減温する方法としては、排ガスに直接水を噴射して水の蒸発潜熱によって減温する方法がある。
【０００３】
近年、ごみ処理施設においてはダイオキシンの再合成防止の観点から、排ガスの温度を低下させる要求が多く発生しており、特に排熱ボイラを設置しないごみ処理施設の場合には、減温塔を設置して、高温の排ガスをダイオキシンの再合成が防止できる低温まで減温することが要求されている。
【０００４】
このため、従来より例えば、塔状容器内に排ガスを流入して冷却水を噴射することにより排ガスを冷却するようにしてある減温塔において、上部位置に噴射ノズルを設けた塔状容器と、塔状容器頂部の排ガス入口の上側に、一側より導入される排ガスをガイドベーンで周方向に分散させるようにし且つ底面中央部にガスの出口を設けた分散室と、分散室のガスの出口と塔状容器の排ガス入口との間に設けた垂直方向に延びる多数の細いガス流路を形成させる絞り部とからなるガス導入部を構成したものがある（例えば、特許文献１参照）。
【０００５】
【特許文献１】
特開２００２−２１９３２３号公報
【０００６】
【発明が解決しようとする課題】
上記特許文献１では、燃焼炉から導かれた排ガスは、先ず、ガス導入部の分散室内にてガイドベーンに邪魔されて、その流線が左右方向（周方向）に分散された後、絞り部に向かうようになり、次いで、該絞り部に形成された垂直方向に延びる多数の細い流路を通過することにより、流れ方向が垂直方向下向きに整流された状態になって、塔状容器の頂部中央の排ガス入口より塔状容器内に流入されるようになる。これにより、塔状容器内に流入する排ガスは、周方向に均等に且つ塔状容器中心部を垂直方向下向きに流されることから、噴射される冷却水と排ガスとの効率的な熱交換が行われ、このため冷却水はすべて蒸発させられ、ダストと共に塔状容器内壁面に付着することが防止されるとしている。
【０００７】
上記特許文献１による減温塔では、高温の排ガスを２５０℃程度まで減温する際には有効であった。
【０００８】
しかし、特許文献１の減温塔で排ガスを２５０℃以下の温度に減温しようとした場合には、排ガスの最終到達温度と水温とが近付くために完全蒸発を行わせることが困難であるという問題を有していた。
【０００９】
更に、上記特許文献１に示す如く従来の減温塔では、噴射ノズルを塔状容器上部の１個所（周方向には複数備えられているが、上下方向には１段）に設けている。そして、例えば９００℃の排ガスをダイオキシンの再合成が防止できる１８０℃程度まで減温する場合には、減温塔の出口温度を検出し該出口温度が１８０℃になるように流量制御弁の開度を調節して前記噴射ノズルの噴射量を制御する。しかし、このとき、減温塔に１段のみ設けている噴射ノズルと流量制御弁は、小噴射量から大噴射量まで調節できるよう元々大容量に構成しているために、出口温度の変化に応じて流量制御弁の開度を微調節しても、水の噴射量が大きく変化してしまい、このための応答遅れによる調整過剰によって出口温度を例えば１８０℃の設定温度に精度良く保持することができない。
【００１０】
また、特に、前記した如く減温塔上部の高さ方向１段に噴射ノズルを設けた構成では、噴射ノズルから大量の水を噴射したときに、水滴が微粒とならずに塊を生じたまま落下し易く、塊となった水滴は完全な蒸発が行われ難い。
【００１１】
上記したように、従来の減温塔では、排ガスの最終到達温度と水温とが近付くこと、水噴射の応答遅れ、噴射した水が塊を形成し易いこと等が相俟って、噴射した水の完全蒸発が行われず、そのために排ガス中のダストが湿りを生じ、湿ったダストは減温塔内下部に付着堆積する問題を生じる。更に、このような湿ったダストは、輸送や貯留時等のトラブルの原因となる。従って、従来の減温塔では１８０℃前後のような低温域まで排ガスを減温することは実際上問題を有していた。
【００１２】
本発明は、排ガス中のダストに湿りを生じさせることなく、減温塔出口の排ガス温度を設定温度に精度良く調節できるようにした減温塔の排ガス出口温度制御方法及び装置を提供しようとするものである。
【００１３】
【課題を解決するための手段】
請求項１に記載の発明は、ガス導入口から排ガスを導入してガス導出口から導出する減温塔の前記ガス導入口側に、各々に流量調整弁を備えた噴射ノズルをガスの流動方向に所要の間隔を隔てて２段に設け、更にガス導出口に排ガス温度を検出する温度検出器を設け、一方の噴射ノズルに備えた流量調整弁は、短い時間間隔に設定した狭幅検出時間内における温度検出器の検出温度の平均値の変化に基づいて開度を調節し、他方の噴射ノズルに備えた流量調整弁は、長い時間間隔に設定した広幅検出時間内における検出温度の平均値の変化に基づいて開度を調節して、ガス導出口の排ガス温度を設定温度に保持することを特徴とする減温塔の排ガス出口温度制御方法、に係るものである。
【００１４】
請求項２に記載の発明は、ガス導入口から排ガスを導入してガス導出口から導出する減温塔の前記ガス導入口側に、各々に流量調整弁を備えた噴射ノズルをガスの流動方向に所要の間隔を隔てて２段に設け、更にガス導出口に排ガス温度を検出する温度検出器を設け、一方の噴射ノズルに備えた流量調整弁は、温度検出器の検出温度に基づいて設定された流量調整範囲内で開度を調節し、他方の噴射ノズルに備えた流量調整弁は、前記一方の流量調整弁の開度が流量調整範囲の限界に達したときに温度検出器の検出温度に基づいて開度を調節して、ガス導出口の排ガス温度を設定温度に保持することを特徴とする減温塔の排ガス出口温度制御方法、に係るものである。
【００１５】
請求項３に記載の発明は、ガス導入口から排ガスを導入してガス導出口から導出する減温塔の前記ガス導入口側にガスの流動方向に所要の間隔を隔てて２段に配置した噴射ノズルと、噴射ノズルの夫々に設けた流量調整弁と、前記ガス導出口に設置した温度検出器と、該温度検出器の検出温度を入力し、短い時間間隔に設定した狭幅検出時間内における温度検出器の検出温度の平均値の変化に基づいて一方の流量調整弁の開度を調節し、且つ長い時間間隔に設定した広幅検出時間内における温度検出器の検出温度の平均値の変化に基づいて他方の流量調整弁の開度を調整するようにした制御器と、を備えたことを特徴とする減温塔の排ガス出口温度制御装置、に係るものである。
【００１６】
請求項４に記載の発明は、ガス導入口から排ガスを導入してガス導出口から導出する減温塔の前記ガス導入口側にガスの流動方向に所要の間隔を隔てて２段に配置した噴射ノズルと、噴射ノズルの夫々に設けた流量調整弁と、前記ガス導出口に設置した温度検出器と、温度検出器の検出温度に基づいて設定した流量調整範囲内で一方の流量調整弁の開度を調節し、且つ該一方の流量調整弁の開度が設定した流量制御範囲の限界に達したときに温度検出器の検出温度に基づいて他方の流量調整弁の開度を調節するようにした制御器と、を備えたことを特徴とする減温塔の排ガス出口温度制御装置、に係るものである。
【００１７】
請求項５に記載の発明は、前記各流量調整弁は、各噴射ノズルに水を供給する給水管の戻り管に設けていることを特徴とする請求項３または４に記載の減温塔の排ガス出口温度制御装置、に係るものである。
【００１８】
請求項６に記載の発明は、前記一方の流量調整弁は弁開度に対する噴射流量が小さい小流量調整弁であり、他方の流量調整弁は弁開度に対する噴射流量が大きい大流量調整弁であることを特徴とする請求項３〜５のいずれか１つに記載の減温塔の排ガス出口温度制御装置、に係るものである。
【００１９】
請求項７に記載の発明は、前記大流量調整弁は、小流量調整弁に対してガス導入口に近い位置に設けられていることを特徴とする請求項６に記載の減温塔の排ガス出口温度制御装置、に係るものである。
【００２０】
上記手段によれば、以下のように作用する。
【００２１】
温度検出器による検出温度が細かく変動する小さな変動に対しては、狭幅検出時間で捕えた検出温度の平均値によって一方の噴射ノズルに備えた流量調整弁を微調整して噴射ノズルによる噴射量を微調節し、一方、温度検出器による検出温度の大きな変動に対しては、広幅検出時間で捕えた検出温度の平均値によって他方の噴射ノズルに備えた流量調整弁を調節することで噴射ノズルの噴射量を大きな変化量でベースの調整を行うようにしたので、前記微調整とベースの調整が同時に行われることによって応答遅れを殆ど生じることなくガス導出口の排ガスの温度を精度良く設定温度に保持することができる。
【００２２】
一方の噴射ノズルに備えた流量調整弁は、温度検出器の検出温度に基づいて設定された流量調整範囲内で開度を調節し、他方の噴射ノズルに備えた流量調整弁は、前記一方の流量調整弁の開度が流量調整範囲の限界に達したときに温度検出器の検出温度に基づいて開度を調節するようにしたので、各流量調整弁の調節が１つの目標値に向かって制御されるようになり、よってガス導出口の排ガスの温度が変動することなく設定温度に精度良く制御されるようになる。
【００２３】
各流量調整弁を、各噴射ノズルに水を供給する給水管の戻り管に設けたことにより、噴射ノズルの入口圧力を安定させることができ、よって最大噴射量と最少噴射量の制御幅を広くでき、しかも全噴射域において微細な粒子による噴射が可能になってボタ落ちの問題を防止できる。
【００２４】
弁開度に対する噴射流量が大きい大流量調整弁をガス導入口に近い位置に設け、弁開度に対する噴射流量が小さい小流量調整弁をガス導入口から遠い位置に設けたことにより、噴射ノズルによる噴射水の完全蒸発が更に行われ易くなる。
【００２５】
【発明の実施の形態】
以下、本発明の好適な実施の形態を図面に基づいて説明する。
【００２６】
図１は本発明の減温塔の排ガス出口温度制御装置の実施の一形態を示すもので、図中１は減温塔であり、該減温塔１は、上部のガス導入口２から排ガス３を導入し、下部のガス導出口４から排ガス３を導出するようにしている。
【００２７】
前記減温塔１の上部位置には、上下に所要の間隔を隔てて配置した２段の噴射ノズル５，６を設けている。上下二段に設けられる噴射ノズル５，６の夫々は、減温塔１を取り巻くように複数配置されている。
【００２８】
上段の噴射ノズル５には、給水ポンプ７と圧力調節弁８とを有して一端が給水タンク９に連通した給水管１０の他端が接続されている。更に、噴射ノズル５に形成された図示しない旋回室（ワールチャンバー）には戻り管１０ａが接続されており、該戻り管１０ａに流量調整弁１１を設置することによりフローバックノズルを構成している。このとき、前記流量調整弁１１は、弁開度に対する噴射流量が大きい大流量調整弁１１Ｍとしている。
【００２９】
また、噴射ノズル６には、給水ポンプ１２と圧力調節弁１３とを有して一端が給水タンク９に連通した給水管１４の他端が接続されている。更に、噴射ノズル６に形成された図示しない旋回室（ワールチャンバー）には戻り管１４ａが接続されており、該戻り管１４ａに流量調整弁１５を設置することによりフローバックノズルを構成している。このとき、前記流量調整弁１５は、弁開度に対する噴射流量が小さい小流量調整弁１５Ｌとしている。前記戻り管１０ａと戻り管１４ａは一本に連通されて給水タンク９に導かれている。
【００３０】
前記フローバックノズルの構成は、大流量調整弁１１Ｍ及び小流量調整弁１５Ｌが全開のときには、圧力調節弁８，１３の下流に圧力が立たないために噴射ノズル５，６からは水が噴射されず、一方、大流量調整弁１１Ｍ及び小流量調整弁１５Ｌの開度を絞ると、その開度に応じて圧力調節弁８，１３の下流に圧力が立つことによって噴射ノズル５，６から水が噴射されるようになっている。
【００３１】
前記ガス導出口４には温度検出器１６が設置してあり、該温度検出器１６の検出温度１７は制御器１８に入力されている。
【００３２】
制御器１８は、前記噴射ノズル５，６に供給する水の圧力が所定の一定圧力に保持されるように前記各圧力調節弁８，１３を制御する。
【００３３】
一方、前記制御器１８は、温度検出器１６の検出温度１７に基づいて、大流量調整弁１１Ｍ及び小流量調整弁１５Ｌの開度を調節し、前記噴射ノズル５，６から減温塔１内に噴射する水の量を調節することにより、ガス導出口４の排ガス温度が所定の設定温度Ｔ（例えば１８０℃）になるように制御している。
【００３４】
図１の構成において、噴射ノズル５，６よりも上流側の給水管１０，１４に、流量調整弁１１，１５を設置することも可能であるが、このようにした場合には、噴射ノズル５，６入口の圧力の一定保持が難しく、そのために最大噴射量と最少噴射量の制御幅が狭く制限され、しかも噴射量が小さい時にボタ落ちを生じる問題がある。これに対し、前記したように噴射ノズル５，６の戻り管１０ａ，１４ａに大流量調整弁１１Ｍ及び小流量調整弁１５Ｌを設置したフローバックノズルの構成によれば、噴射ノズル５，６の入口圧力を安定させることができ、よって最大噴射量と最少噴射量の制御幅を広くでき、しかも全噴射域において微細な粒子による噴射が可能になってボタ落ちの問題を防止できる。従って、図１の構成によれば、減温塔１によって高温の排ガス３を減温するのに好適に用いることができる。
【００３５】
また、噴射ノズル５，６に、専用の給水ポンプ７，１２を備えた独自の給水管１０，１４を接続して給水を行うようにしたので、１つの給水ポンプを供用した場合のように一方の噴射ノズルを噴射したときの圧力の変動の影響を他方の噴射ノズルが受けるという問題を防止でき、噴射ノズル５，６に対する給水の圧力の変動を更に低減できる。
【００３６】
次に、図１に示した構成において減温塔の出口温度を制御する２つの制御方法について説明する。
【００３７】
第１の制御方法について図１及び図２を参照して説明する。図２は、ガス導出口４の排ガス３の温度が変動したときの検出温度と時間との関係を模式的に表わした線図であり、図中Ｔは設定温度（例えば１８０℃）である。
【００３８】
制御器１８は、前記温度検出器１６の検出温度１７を入力しており、図２に示す如く、短い時間間隔に設定した狭幅検出時間Ｓ_１内における温度を検出してその平均値Ｔ_１を求めている。一方、長い時間間隔に設定した狭幅検出時間Ｓ_２内における温度を検出してその平均値Ｔ_２を求めている。
【００３９】
そして、狭幅検出時間Ｓ_１で検出した検出温度１７の平均値Ｔ_１の比較的小さい変化幅の変化に対しては小流量調整弁１５Ｌの開度を微調節して噴射ノズル６による噴射量を調整する。
【００４０】
一方、狭幅検出時間Ｓ_２で検出した検出温度１７の平均値Ｔ_２の比較的大きな変化幅の変化に対しては大流量調整弁１１Ｍの開度を調整することにより噴射ノズル６の噴射量を調整する。
【００４１】
図３は上記第１の制御方法を実施した小流量調整弁１５Ｌの弁開度Ａと、大流量調整弁１１Ｍの弁開度Ｂとを示したものであり、小流量調整弁１５Ｌの弁開度Ａは大きく変動しており、大流量調整弁１１Ｍの弁開度Ｂは小さい変動となっている。
【００４２】
上記した第１の制御方法によれば、温度検出器１６による検出温度１７が細かく変動する小さな変動に対しては、狭幅検出時間Ｓ_１で捕えた検出温度１７の平均値Ｔ_１によって小流量調整弁１５Ｌが図３に示す弁開度Ａの如く大きく変化（噴射流量の変化は小さい）されて噴射ノズル６の噴射量を微調整する。
【００４３】
一方、温度検出器１６による検出温度１７の大きな変動に対しては、広幅検出時間Ｓ_２で捕えた検出温度１７の平均値Ｔ_２によって大流量調整弁１１Ｍが図３に示す弁開度Ｂの如く小さく変化（噴射流量の変化は大きい）されて噴射ノズル５による大きな変化量での調整（ベースの調整）を行うようにしたので、微調整とベースの調整が同時に行われることによって応答遅れを殆ど生じることなくガス導出口４の排ガス３の温度を精度良く設定温度Ｔに保持することができる。
【００４４】
第２の制御方法について図１及び図４を参照して説明する。図４は、大流量調整弁１１Ｍ及び小流量調整弁１５Ｌの、開度と噴射流量との関係を模式的に表わした線図であり、大流量調整弁１１Ｍは弁開度に対する噴射流量が大きく、小流量調整弁１５Ｌは弁開度に対する噴射流量が小さくなっている。
【００４５】
更に、この場合の制御器１８’は、小流量調整弁１５Ｌによる開度を、例えば４０％〜６０％の範囲とする設定流量範囲Ｘを設定するようにしており、また、大流量調整弁１１Ｍの開度を前記設定流量範囲Ｘより大きい、例えば２０％〜８０％の使用範囲で制御するようにしている。
【００４６】
そして、制御器１８’は、前記温度検出器１６による検出温度１７が変化すると、検出温度１７が設定温度Ｔ（例えば１８０℃）になるように、まず小流量調整弁１５Ｌの開度を調節する。このとき、小流量調整弁１５Ｌは弁開度に対する噴射流量が小さいので、検出温度１７の小さな変化に対して精度良く追従し、微調整を効果的に実施できる。
【００４７】
一方、検出温度１７の変化が大きくなると、小流量調整弁１５Ｌに設定した設定流量範囲Ｘでは調節できない限界（４０％以下、及び６０％以上）になる。このように、小流量調整弁１５Ｌの開度が設定流量範囲Ｘの限界に達すると、制御器１８’は、前記温度検出器１６の検出温度１７に基づいて、大流量調整弁１１Ｍの開度を調節範囲Ｙ_１及びＹ_２内で調節し、検出温度１７が設定温度Ｔ（例えば１８０℃）になるように制御する。
【００４８】
上記した第２の制御方法によれば、小流量調整弁１５Ｌと大流量調整弁１１Ｍとの調節が１つの目標値に向かって制御されるようになるので、ガス導出口４の排ガス３の温度が変動することなく設定温度に精度良く制御されるようになる。
【００４９】
尚、図１の形態では戻り管１０ａ，１４ａに流量調整弁１１，１５を設けたフローバックノズルの構成とした場合について説明したが、戻り管を備えることなく、給水管に流量調整弁を設置した場合にも、前記フローバックノズルの構成による効果は期待できないが、２段に設けた噴射ノズルによる噴射を別個に制御することによって得られる効果は発揮することができる。
【００５０】
また、前記形態では、大流量調整弁１１Ｍをガス導入口２に近い上段に設け、小流量調整弁１５Ｌをガス導入口２から遠い下段に設けた場合について説明したが、大流量調整弁１１Ｍと小流量調整弁１５Ｌは上下を逆転して設けてもよく、また流量調整弁１１と流量調整弁１５を同等の性能（開度に対する噴射流量）を有したものとしてもよい。
【００５１】
更に、本発明は上記形態例にのみ限定されるものではなく、本発明の要旨を逸脱しない範囲内において種々変更を加え得ることは勿論である。
【００５２】
【発明の効果】
本発明によれば、以下の如く優れた効果を奏し得る。
【００５３】
温度検出器による検出温度が細かく変動する小さな変動に対しては、狭幅検出時間で捕えた検出温度の平均値によって一方の噴射ノズルに備えた流量調整弁を微調整して噴射ノズルによる噴射量を微調節し、一方、温度検出器による検出温度の大きな変動に対しては、広幅検出時間で捕えた検出温度の平均値によって他方の噴射ノズルに備えた流量調整弁を調節することで噴射ノズルの噴射量を大きな変化量でベースの調整を行うようにしたので、前記微調整とベースの調整が同時に行われることにより、応答遅れを殆ど生じることなくガス導出口の排ガスの温度を精度良く設定温度に保持することができる。
【００５４】
一方の噴射ノズルに備えた流量調整弁は、温度検出器の検出温度に基づいて設定された流量調整範囲内で開度を調節し、他方の噴射ノズルに備えた流量調整弁は、前記一方の流量調整弁の開度が流量調整範囲の限界に達したときに温度検出器の検出温度に基づいて開度を調節するようにしたので、各流量調整弁の調節が１つの目標値に向かって制御されるようになり、よってガス導出口の排ガスの温度が変動することなく設定温度に精度良く制御されるようになる。
【００５５】
各流量調整弁を、各噴射ノズルに水を供給する給水管の戻り管に設けたことにより、噴射ノズルの入口圧力を安定させることができ、よって最大噴射量と最少噴射量の制御幅を広くでき、しかも全噴射域において微細な粒子による噴射が可能になってボタ落ちの問題を防止できる。
【００５６】
弁開度に対する噴射流量が大きい大流量調整弁をガス導入口に近い位置に設け、弁開度に対する噴射流量が小さい小流量調整弁をガス導入口から遠い位置に設けたことにより、噴射ノズルによる噴射水の完全蒸発が更に行われ易くなる。
【図面の簡単な説明】
【図１】本発明の減温塔の排ガス出口温度制御装置の実施の一形態を示すブロック図である。
【図２】ガス導出口の排ガスの温度が変動したときの検出温度と時間との関係を模式的に表わした線図である。
【図３】小流量調整弁の弁開度と大流量調整弁の弁開度とを実測した値の線図である。
【図４】大流量調整弁及び小流量調整弁の、開度と噴射流量との関係を模式的に表わした線図である。
【符号の説明】
１減温塔
２ガス導入口
３排ガス
４ガス導出口
５噴射ノズル
６噴射ノズル
１０給水管
１０ａ戻り管
１１流量調整弁
１１Ｍ大流量調整弁
１４給水管
１４ａ戻り管
１５流量調整弁
１５Ｌ小流量調整弁
１６温度検出器
１７検出温度
１８制御器
１８’ 制御器
Ｓ_１狭幅検出時間
Ｓ_２広幅検出時間
Ｔ設定温度
Ｔ_１平均値
Ｔ_２平均値
Ｘ設定流量範囲[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method and an apparatus for controlling the temperature of an exhaust gas outlet of a cooling tower used for reducing the temperature of exhaust gas to a required set temperature in a combustion facility having a combustion furnace such as a waste treatment facility or a cement plant.
[0002]
[Prior art]
As a method of reducing the temperature of exhaust gas containing dust in a combustion facility having a combustion furnace such as a waste treatment facility or a cement plant, there is a method of directly injecting water into the exhaust gas and reducing the temperature by latent heat of vaporization of water. .
[0003]
In recent years, from the viewpoint of preventing re-synthesis of dioxins, many requests have been made to lower the temperature of exhaust gas in waste treatment facilities. Particularly, in the case of waste treatment facilities that do not have waste heat boilers, a cooling tower is installed. Then, it is required to reduce the temperature of the high-temperature exhaust gas to a low temperature at which re-synthesis of dioxin can be prevented.
[0004]
For this reason, conventionally, for example, in a cooling tower configured to cool the exhaust gas by injecting the exhaust gas into the tower-shaped container and injecting cooling water, a tower-shaped container provided with an injection nozzle at an upper position, A dispersing chamber in which exhaust gas introduced from one side is dispersed in the circumferential direction by a guide vane above the exhaust gas inlet at the top of the tower-shaped vessel, and a gas outlet is provided at the center of the bottom surface, and a gas outlet of the dispersing chamber. There is a gas inlet configured to include a plurality of narrow gas passages extending in a vertical direction and provided between an exhaust gas inlet of a tower-shaped vessel and a gas inlet (see, for example, Patent Document 1).
[0005]
[Patent Document 1]
JP 2002-219323 A
[Problems to be solved by the invention]
In Patent Literature 1, the exhaust gas led from the combustion furnace is first disturbed by the guide vanes in the dispersion chamber of the gas introduction unit, and its streamlines are dispersed in the left-right direction (circumferential direction). Then, by passing through a large number of narrow flow paths extending in the vertical direction formed in the throttle portion, the flow direction is rectified vertically downward, the top of the tower-shaped vessel The gas flows into the tower vessel from the central exhaust gas inlet. As a result, the exhaust gas flowing into the tower-shaped vessel flows evenly in the circumferential direction and vertically downward in the center of the tower-shaped vessel, so that efficient heat exchange between the injected cooling water and the exhaust gas is performed. For this reason, all the cooling water is evaporated to prevent the cooling water from adhering to the inner wall surface of the tower-like container together with the dust.
[0007]
The cooling tower according to Patent Literature 1 was effective in reducing the temperature of high-temperature exhaust gas to about 250 ° C.
[0008]
However, when the exhaust gas is to be cooled to a temperature of 250 ° C. or less in the cooling tower of Patent Document 1, it is difficult to completely evaporate the exhaust gas because the final temperature of the exhaust gas and the water temperature are close to each other. Had a problem.
[0009]
Further, as shown in Patent Document 1, in the conventional cooling tower, the injection nozzle is provided at one location in the upper part of the tower-shaped vessel (a plurality of nozzles are provided in the circumferential direction, but one stage in the vertical direction). For example, when the temperature of the exhaust gas at 900 ° C. is reduced to about 180 ° C. at which dioxin resynthesis can be prevented, the outlet temperature of the cooling tower is detected, and the flow control valve is opened so that the outlet temperature becomes 180 ° C. The injection amount of the injection nozzle is controlled by adjusting the degree. However, at this time, the injection nozzle and the flow control valve provided only in one stage in the cooling tower are originally configured to have a large capacity so that the injection amount can be adjusted from a small injection amount to a large injection amount. Even if the degree of opening of the flow control valve is finely adjusted accordingly, the water injection amount changes greatly, and the outlet temperature is accurately maintained at a set temperature of, for example, 180 ° C. due to excessive adjustment due to a response delay. Can not.
[0010]
Further, in particular, as described above, in the configuration in which the injection nozzle is provided at one stage in the height direction above the cooling tower, when a large amount of water is injected from the injection nozzle, water droplets remain in a lump without forming fine particles. It is easy to fall, and it is difficult to completely evaporate the water droplets formed as a lump.
[0011]
As described above, in the conventional cooling tower, the final temperature of the exhaust gas and the water temperature are close to each other, the response of the water injection is delayed, and the injected water is likely to form a lump. Is not completely evaporated, so that the dust in the exhaust gas is moistened, and the moist dust adheres and accumulates in the lower part of the cooling tower. Further, such wet dust causes trouble during transportation and storage. Therefore, in the conventional cooling tower, there is a practical problem in reducing the temperature of the exhaust gas to a low temperature range such as around 180 ° C.
[0012]
An object of the present invention is to provide a method and an apparatus for controlling the temperature of an exhaust gas outlet of a cooling tower, in which the temperature of the exhaust gas at the outlet of the cooling tower can be accurately adjusted to a set temperature without causing the dust in the exhaust gas to become wet. Things.
[0013]
[Means for Solving the Problems]
According to the first aspect of the present invention, an injection nozzle provided with a flow control valve on each of the gas introduction ports of a cooling tower that introduces exhaust gas from a gas introduction port and derives from a gas discharge port has a flow direction of gas. Is provided in two stages at a required interval, and a temperature detector for detecting exhaust gas temperature is provided at the gas outlet, and the flow control valve provided on one of the injection nozzles has a narrow detection time set at a short time interval. The opening is adjusted based on the change in the average value of the temperature detected by the temperature detector in the inside, and the flow control valve provided in the other injection nozzle is the average value of the detected temperature in the wide detection time set at a long time interval. And controlling the exhaust gas temperature of the gas outlet at the set temperature by adjusting the opening degree based on the change of the exhaust gas temperature.
[0014]
According to the second aspect of the present invention, an exhaust nozzle which is provided with a flow control valve on each gas inlet side of a cooling tower for introducing exhaust gas from a gas inlet and leading it out of a gas outlet is provided with a gas flow direction. Are provided in two stages with a required interval, and a temperature detector for detecting exhaust gas temperature is provided at the gas outlet, and a flow control valve provided for one injection nozzle is set based on the temperature detected by the temperature detector. The opening degree is adjusted within the set flow rate adjustment range, and the flow rate adjustment valve provided in the other injection nozzle detects the temperature detector when the opening degree of the one flow rate adjustment valve reaches the limit of the flow rate adjustment range. The present invention relates to a method for controlling an exhaust gas outlet temperature of a cooling tower, wherein an opening degree is adjusted based on a temperature to maintain an exhaust gas temperature at a gas outlet at a set temperature.
[0015]
According to a third aspect of the present invention, the exhaust gas is introduced from the gas inlet and the gas is introduced from the gas outlet. An injection nozzle, a flow control valve provided for each of the injection nozzles, a temperature detector installed at the gas outlet, and a detection temperature of the temperature detector are input, and a narrow detection time set at a short time interval is input. The opening degree of one of the flow control valves is adjusted based on the change in the average value of the temperature detected by the temperature detector in the above, and the change in the average value of the temperature detected by the temperature detector within a wide detection time set at a long time interval And a controller that adjusts the opening of the other flow rate control valve based on the above.
[0016]
In the invention according to claim 4, the exhaust gas is introduced from the gas introduction port and is disposed in two stages at a required interval in the gas flow direction on the side of the gas introduction port of the cooling tower that is derived from the gas outlet. Injection nozzle, a flow control valve provided in each of the injection nozzles, a temperature detector installed in the gas outlet, and one of the flow control valves within a flow control range set based on the temperature detected by the temperature detector. When the opening of one of the flow control valves reaches the limit of the set flow control range, the opening of the other flow control valve is adjusted based on the temperature detected by the temperature detector. And an exhaust gas outlet temperature control device of the cooling tower.
[0017]
The invention according to claim 5 is characterized in that each of the flow control valves is provided in a return pipe of a water supply pipe that supplies water to each injection nozzle. An exhaust gas outlet temperature control device.
[0018]
According to a sixth aspect of the present invention, the one flow control valve is a small flow control valve having a small injection flow rate with respect to the valve opening, and the other flow control valve is a large flow control valve having a large injection flow rate with respect to the valve opening. An exhaust gas outlet temperature control device for a temperature-reducing tower according to any one of claims 3 to 5, wherein
[0019]
The exhaust gas of the cooling tower according to claim 6, wherein the large flow regulating valve is provided at a position close to the gas inlet with respect to the small flow regulating valve. Outlet temperature control device.
[0020]
According to the above means, the following operation is performed.
[0021]
For small fluctuations in which the temperature detected by the temperature detector fluctuates finely, the flow rate adjustment valve provided for one of the injection nozzles is fine-tuned based on the average value of the detected temperatures captured in the narrow detection time, and the amount of injection by the injection nozzle On the other hand, for a large fluctuation in the temperature detected by the temperature detector, the average value of the detected temperatures captured in the wide detection time adjusts the flow control valve provided in the other injection nozzle to adjust the injection nozzle. Since the base adjustment is performed with a large change amount of the injection amount of the gas, the fine adjustment and the base adjustment are performed at the same time, so that the temperature of the exhaust gas at the gas outlet is accurately set to the set temperature with almost no response delay. Can be held.
[0022]
The flow control valve provided on one of the injection nozzles adjusts the opening within a flow control range set based on the temperature detected by the temperature detector, and the flow control valve provided on the other injection nozzle has the one When the opening of the flow control valve reaches the limit of the flow control range, the opening is adjusted based on the temperature detected by the temperature detector, so that the adjustment of each flow control valve is directed toward one target value. As a result, the temperature of the exhaust gas at the gas outlet is accurately controlled to the set temperature without fluctuating.
[0023]
By providing each flow control valve on the return pipe of the water supply pipe that supplies water to each injection nozzle, the inlet pressure of the injection nozzle can be stabilized, and the control range of the maximum injection amount and the minimum injection amount can be widened. In addition, fine particles can be sprayed in the entire spray area, and the problem of dropping can be prevented.
[0024]
By providing a large flow control valve with a large injection flow rate to the valve opening near the gas inlet and a small flow control valve with a small injection flow to the valve opening far from the gas inlet, the injection nozzle Complete evaporation of the injection water is further facilitated.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
[0026]
FIG. 1 shows an embodiment of an exhaust gas outlet temperature control device for a temperature reducing tower according to the present invention. In the figure, reference numeral 1 denotes a temperature reducing tower. 3 is introduced, and the exhaust gas 3 is led out from the lower gas outlet 4.
[0027]
At the upper position of the cooling tower 1, two-stage injection nozzles 5 and 6 arranged vertically and at a required interval are provided. A plurality of injection nozzles 5 and 6 provided in two stages, upper and lower, are arranged so as to surround the cooling tower 1.
[0028]
The other end of a water supply pipe 10 having a water supply pump 7 and a pressure control valve 8 and having one end communicating with a water supply tank 9 is connected to the upper injection nozzle 5. Further, a return pipe 10a is connected to a swirl chamber (whirl chamber) (not shown) formed in the injection nozzle 5, and a flow control valve 11 is provided in the return pipe 10a to constitute a flow back nozzle. . At this time, the flow control valve 11 is a large flow control valve 11M having a large injection flow rate with respect to the valve opening.
[0029]
Further, the injection nozzle 6 is connected to the other end of a water supply pipe 14 having a water supply pump 12 and a pressure control valve 13 and having one end communicating with the water supply tank 9. Further, a return pipe 14a is connected to a swirl chamber (whirl chamber) (not shown) formed in the injection nozzle 6, and a flow control valve 15 is provided in the return pipe 14a to constitute a flow back nozzle. . At this time, the flow control valve 15 is a small flow control valve 15L having a small injection flow rate with respect to the valve opening. The return pipe 10a and the return pipe 14a communicate with each other and are led to the water supply tank 9.
[0030]
The configuration of the flow-back nozzle is such that when the large flow control valve 11M and the small flow control valve 15L are fully opened, water does not flow downstream of the pressure control valves 8 and 13 so that water is injected from the injection nozzles 5 and 6. On the other hand, when the openings of the large flow control valve 11M and the small flow control valve 15L are reduced, the pressure rises downstream of the pressure control valves 8, 13 in accordance with the openings, so that water is injected from the injection nozzles 5, 6. It is to be injected.
[0031]
A temperature detector 16 is provided at the gas outlet 4, and a detected temperature 17 of the temperature detector 16 is input to a controller 18.
[0032]
The controller 18 controls the pressure regulating valves 8 and 13 so that the pressure of water supplied to the injection nozzles 5 and 6 is maintained at a predetermined constant pressure.
[0033]
On the other hand, the controller 18 adjusts the opening degree of the large flow control valve 11M and the small flow control valve 15L based on the detected temperature 17 of the temperature detector 16, and controls the injection nozzles 5, 6 from inside the cooling tower 1. The exhaust gas temperature at the gas outlet 4 is controlled to a predetermined set temperature T (for example, 180 ° C.) by adjusting the amount of water injected into the gas outlet 4.
[0034]
In the configuration of FIG. 1, it is possible to install the flow control valves 11 and 15 in the water supply pipes 10 and 14 on the upstream side of the injection nozzles 5 and 6, however, in such a case, the injection nozzle 5 , 6 is difficult to maintain a constant pressure, so that the control widths of the maximum injection amount and the minimum injection amount are narrowly limited, and there is a problem that drop occurs when the injection amount is small. On the other hand, according to the configuration of the flow back nozzle in which the large flow regulating valve 11M and the small flow regulating valve 15L are installed in the return pipes 10a and 14a of the injection nozzles 5 and 6 as described above, the inlets of the injection nozzles 5 and 6 are provided. The pressure can be stabilized, the control range of the maximum injection amount and the minimum injection amount can be widened, and fine particles can be injected in the entire injection range, so that the problem of dropping can be prevented. Therefore, according to the configuration of FIG. 1, it is possible to suitably use the temperature reducing tower 1 to reduce the temperature of the high-temperature exhaust gas 3.
[0035]
In addition, since the water supply is performed by connecting the water supply pipes 10 and 14 provided with the exclusive water supply pumps 7 and 12 to the injection nozzles 5 and 6, one side water supply pump is used as in the case where one water supply pump is used. Can be prevented from being affected by the fluctuation of the pressure when the other injection nozzle is injected, and the fluctuation of the pressure of the water supplied to the injection nozzles 5 and 6 can be further reduced.
[0036]
Next, two control methods for controlling the outlet temperature of the cooling tower in the configuration shown in FIG. 1 will be described.
[0037]
The first control method will be described with reference to FIGS. FIG. 2 is a diagram schematically showing the relationship between the detected temperature and the time when the temperature of the exhaust gas 3 at the gas outlet 4 fluctuates, where T is a set temperature (for example, 180 ° C.).
[0038]
Controller 18, the which receives a detection temperature 17 temperature detector 16, as shown in FIG. 2, by detecting the temperature in the short time narrow detection time S ₁ set to the interval average value T ₁ Seeking. On the other hand, seeking the average value T ₂ to detect the temperature in a long time narrow detection time S in ₂ set at intervals.
[0039]
Then, the injection amount by the average value T injection nozzle 6 by finely adjusting the opening of the small flow rate adjusting valve 15L for changes in a relatively small change in the width of _one of the detection temperature 17 detected by the narrow detection time S ₁ To adjust.
[0040]
On the other hand, the injection amount of the injection nozzle 6 by adjusting the degree of opening of a large flow rate adjusting valve 11M for changes in a relatively large range of change in the average value T ₂ of the detected temperature 17 detected by the narrow detection time S ₂ To adjust.
[0041]
FIG. 3 shows the valve opening A of the small flow regulating valve 15L and the valve opening B of the large flow regulating valve 11M in which the first control method is performed. The degree A fluctuates greatly, and the valve opening degree B of the large flow regulating valve 11M fluctuates slightly.
[0042]
According to the first control method described above, for small variations vary minutely the temperature detected 17 by the temperature detector 16, the small flow rate by the average value T ₁ of the detection temperature 17 captured by the narrow detection time S ₁ The adjustment valve 15L is greatly changed (the change in the injection flow rate is small) like the valve opening A shown in FIG. 3 to finely adjust the injection amount of the injection nozzle 6.
[0043]
On the other hand, for large fluctuations in the detected temperature 17 by the temperature detector 16, the average value T ₂ of the temperature detected 17 captured by the wide detection time S ₂ is a high flow rate regulating valve 11M of the valve opening B shown in FIG. 3 Since the adjustment (the adjustment of the base) is performed with a small change (the change of the injection flow rate is large) by the injection nozzle 5, the fine adjustment and the adjustment of the base are simultaneously performed, so that the response delay is reduced. The temperature of the exhaust gas 3 at the gas outlet 4 can be accurately maintained at the set temperature T with almost no occurrence.
[0044]
The second control method will be described with reference to FIGS. FIG. 4 is a diagram schematically showing the relationship between the opening degree and the injection flow rate of the large flow rate adjustment valve 11M and the small flow rate adjustment valve 15L. The large flow rate adjustment valve 11M has a large injection flow rate with respect to the valve opening degree. The small flow rate adjusting valve 15L has a small injection flow rate with respect to the valve opening.
[0045]
Further, the controller 18 'in this case sets the set flow rate range X such that the opening degree of the small flow rate control valve 15L is, for example, in a range of 40% to 60%, and the large flow rate control valve 11M. Is controlled in a use range larger than the set flow rate range X, for example, 20% to 80%.
[0046]
When the temperature 17 detected by the temperature detector 16 changes, the controller 18 'first adjusts the opening degree of the small flow regulating valve 15L so that the detected temperature 17 becomes the set temperature T (for example, 180 ° C.). . At this time, since the small flow rate adjusting valve 15L has a small injection flow rate with respect to the valve opening degree, the small flow rate adjusting valve 15L can accurately follow a small change in the detected temperature 17 and perform fine adjustment effectively.
[0047]
On the other hand, when the change in the detected temperature 17 increases, the limit cannot be reached within the set flow rate range X set for the small flow rate regulating valve 15L (40% or less and 60% or more). As described above, when the opening of the small flow regulating valve 15L reaches the limit of the set flow range X, the controller 18 'determines the opening of the large flow regulating valve 11M based on the detected temperature 17 of the temperature detector 16. the adjusted within adjustment range _{Y 1} and _{Y 2,} the detected temperature 17 is controlled to be the set temperature T (e.g., 180 ° C.).
[0048]
According to the second control method described above, the adjustment of the small flow control valve 15L and the large flow control valve 11M is controlled toward one target value. Is accurately controlled to the set temperature without fluctuation.
[0049]
In the embodiment of FIG. 1, a description has been given of a case where the flow-back nozzle has a configuration in which the flow control valves 11 and 15 are provided in the return pipes 10 a and 14 a, but the flow control valve is installed in the water supply pipe without the return pipe. Also in this case, the effect of the configuration of the flow back nozzle cannot be expected, but the effect obtained by separately controlling the injection by the injection nozzles provided in two stages can be exhibited.
[0050]
Further, in the above-described embodiment, the case where the large flow control valve 11M is provided in the upper part near the gas inlet 2 and the small flow control valve 15L is provided in the lower part far from the gas inlet 2 has been described. The small flow control valve 15L may be provided upside down, or the flow control valve 11 and the flow control valve 15 may have the same performance (injection flow rate with respect to opening).
[0051]
Further, the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the spirit of the present invention.
[0052]
【The invention's effect】
According to the present invention, the following excellent effects can be obtained.
[0053]
For small fluctuations in which the temperature detected by the temperature detector fluctuates finely, the flow rate adjustment valve provided for one of the injection nozzles is fine-tuned based on the average value of the detected temperatures captured in the narrow detection time, and the amount of injection by the injection nozzle On the other hand, for a large fluctuation in the temperature detected by the temperature detector, the average value of the detected temperatures captured in the wide detection time adjusts the flow control valve provided in the other injection nozzle to adjust the injection nozzle. Since the base adjustment is performed with a large change amount of the injection amount, the fine adjustment and the base adjustment are performed at the same time, so that the temperature of the exhaust gas at the gas outlet can be accurately set with almost no response delay. Can be kept at temperature.
[0054]
The flow control valve provided on one of the injection nozzles adjusts the opening within a flow control range set based on the temperature detected by the temperature detector, and the flow control valve provided on the other injection nozzle has the one When the opening of the flow control valve reaches the limit of the flow control range, the opening is adjusted based on the temperature detected by the temperature detector, so that the adjustment of each flow control valve is directed toward one target value. As a result, the temperature of the exhaust gas at the gas outlet is accurately controlled to the set temperature without fluctuating.
[0055]
By providing each flow control valve on the return pipe of the water supply pipe that supplies water to each injection nozzle, it is possible to stabilize the inlet pressure of the injection nozzle, and thus to widen the control range of the maximum injection amount and the minimum injection amount. In addition, fine particles can be sprayed in the entire spray area, and the problem of dropping can be prevented.
[0056]
By providing a large flow control valve with a large injection flow rate to the valve opening near the gas inlet and a small flow control valve with a small injection flow to the valve opening far from the gas inlet, the injection nozzle Complete evaporation of the injection water is further facilitated.
[Brief description of the drawings]
FIG. 1 is a block diagram showing one embodiment of an exhaust gas outlet temperature control device of a temperature reducing tower according to the present invention.
FIG. 2 is a diagram schematically showing a relationship between a detected temperature and time when the temperature of exhaust gas at a gas outlet changes.
FIG. 3 is a diagram of values obtained by actually measuring a valve opening degree of a small flow regulating valve and a valve opening degree of a large flow regulating valve.
FIG. 4 is a diagram schematically illustrating a relationship between an opening degree and an injection flow rate of a large flow rate adjustment valve and a small flow rate adjustment valve.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 cooling tower 2 gas inlet 3 exhaust gas 4 gas outlet 5 injection nozzle 6 injection nozzle 10 water supply pipe 10a return pipe 11 flow control valve 11M large flow control valve 14 water supply pipe 14a return pipe 15 flow control valve 15L small flow control valve 16 Temperature detector 17 Detected temperature 18 Controller 18 'Controller S ₁ Narrow detection time S ₂ Wide detection time T Set temperature T ₁ Average value T ₂ Average value X Set flow rate range

Claims

On the gas inlet side of the cooling tower where the exhaust gas is introduced from the gas inlet and led out from the gas outlet, two injection nozzles each having a flow control valve are provided at a required interval in the gas flow direction. Is provided at the gas outlet, and a temperature detector for detecting the exhaust gas temperature is provided at the gas outlet, and the flow control valve provided on one of the injection nozzles is provided with a detection temperature of the temperature detector within a narrow detection time set at a short time interval. The opening is adjusted based on the change in the average value, and the flow control valve provided on the other injection nozzle adjusts the opening based on the change in the average value of the detected temperature within a wide detection time set at a long time interval. And maintaining the exhaust gas temperature at the gas outlet at a set temperature.

On the gas inlet side of the cooling tower where the exhaust gas is introduced from the gas inlet and led out from the gas outlet, two injection nozzles each having a flow control valve are provided at a required interval in the gas flow direction. And a temperature detector for detecting the temperature of the exhaust gas at the gas outlet, and the flow control valve provided on one of the injection nozzles has an opening within a flow control range set based on the temperature detected by the temperature detector. The flow control valve provided in the other injection nozzle adjusts the opening based on the temperature detected by the temperature detector when the opening of the one flow control valve reaches the limit of the flow control range. And maintaining the exhaust gas temperature at the gas outlet at a set temperature.

Injection nozzles arranged in two stages at a required interval in the gas flow direction on the side of the gas introduction port of the cooling tower where exhaust gas is introduced from the gas introduction port and derived from the gas discharge port, and each of the injection nozzles The flow control valve provided, the temperature detector installed at the gas outlet, and the detected temperature of the temperature detector are input, and the average of the detected temperatures of the temperature detector within a narrow detection time set at a short time interval The opening degree of one of the flow control valves is adjusted based on the change in the value, and the other flow control valve is adjusted based on the change in the average value of the temperature detected by the temperature detector within the wide detection time set at a long time interval. An exhaust gas outlet temperature control device for a cooling tower, comprising: a controller configured to adjust an opening degree.

Injection nozzles arranged in two stages at a required interval in the gas flow direction on the side of the gas introduction port of the cooling tower where exhaust gas is introduced from the gas introduction port and derived from the gas discharge port, and each of the injection nozzles A flow control valve provided, a temperature detector installed at the gas outlet, and an opening of one of the flow control valves within a flow control range set based on a temperature detected by the temperature detector, and A controller that adjusts the opening of the other flow control valve based on the temperature detected by the temperature detector when the opening of the flow control valve reaches the limit of the set flow control range. An exhaust gas outlet temperature control device for a cooling tower.

5. The exhaust gas outlet temperature control device for a cooling tower according to claim 3, wherein each of the flow control valves is provided in a return pipe of a water supply pipe that supplies water to each injection nozzle. 6.

4. The valve according to claim 3, wherein the one flow control valve is a small flow control valve having a small injection flow with respect to the valve opening, and the other flow control valve is a large flow control valve having a large injection flow with respect to the valve opening. 6. The exhaust gas outlet temperature control device for a desupercooling tower according to any one of items 1 to 5,

The exhaust gas outlet temperature control device for a temperature reduction tower according to claim 6, wherein the large flow control valve is provided at a position closer to a gas inlet with respect to the small flow control valve.