JP3544689B2

JP3544689B2 - Start-up controller for variable-pressure once-through boiler

Info

Publication number: JP3544689B2
Application number: JP19632393A
Authority: JP
Inventors: 祐司国広
Original assignee: Babcock Hitachi KK
Current assignee: Mitsubishi Power Ltd
Priority date: 1993-08-06
Filing date: 1993-08-06
Publication date: 2004-07-21
Anticipated expiration: 2019-07-21
Also published as: JPH0755103A

Description

【０００１】
【産業上の利用分野】
本発明は、ボイラ点火からタービン通気に至るまでの昇温・昇圧時間を目標スケジュール通りに制御するための変圧貫流ボイラの起動制御装置に関する。
【０００２】
【従来の技術】
一般に、火力発電所で稼働する変圧貫流ボイラは、消費電力量が低下する夜間は停止され、翌朝消費電力量が増加する時刻にあわせて起動される。変圧貫流ボイラの起動は、ボイラ点火時から主蒸気温度及び圧力をタービン起動に必要な値まで上昇するに要する時間を考慮し、電力の併入が要求される時刻よりもこの時間だけ早い時刻に行なわれる。したがって、ボイラの昇温・昇圧は、電力の併入が要求される時刻に間にあわせるべく、当初予定されたスケジュール通りに行なわれることが特に要求される。また、ボイラの昇温・昇圧に要する時間は、燃料消費量を低減するため、なるべく短時間で所定値に達することが好ましい。
【０００３】
図４に、従来より知られている変圧貫流ボイラとその起動制御装置を示す。この図に示すように、変圧貫流ボイラ１００は、給水ポンプ１と、給水ポンプ１からの給水を加熱する高圧給水加熱器２と、煙道ガスの余熱を利用して給水を予熱する節炭器３と、節炭器３からの給水が導入される水壁構造を有するボイラ４と、ボイラ４にて発生した蒸気を気水分離する気水分離器５と、分離されたボイラ水を貯水する貯水タンク６と、貯水タンク６内の水を節炭器３へ送るボイラ再循環ポンプ７と、気水分離器５で分離された飽和蒸気を過熱して過熱蒸気とする過熱器８と、過熱器８からの過熱蒸気を駆動源として回転する高圧タービン９と、過熱器８と復水器とを連通する過熱器バイパス管路に設置された過熱器バイパス弁１０と、過熱器８の出口管と復水器とを連通するタービンバイパス管路に設置されたタービンバイパス弁１１とを備えている。
【０００４】
一方、起動制御装置２００は、前記ボイラ１００の主蒸気圧力を検出する主蒸気圧力検出器１５と、該主蒸気圧力検出器１５の出力信号に応じた弁開度プログラム信号を出力する関数発生器１６と、該関数発生器１６から出力された弁開度プログラム信号から弁開度の変化率を設定する変化率制限器１７と、該変化率制限器１７の出力信号をそれに応じた弁駆動信号に変換する信号切替器１９とから構成されている。この起動制御装置２００によれば、主蒸気圧力を指標とする弁開度プログラムによって過熱器バイパス弁１０及びタービンバイパス弁１１の開度がプログラム制御され、高圧タービン９を起動する主蒸気の昇温・昇圧が行なわれる。
【０００５】
なお、図中の符号３００は、タービン通気開始後の過熱器バイパス弁１０及びタービンバイパス弁１１の制御装置であって、発電量指令信号を発生する信号発生器１２と、発電量指令信号をそれに対応する主蒸気目標圧力に変換する関数発生器１３と、該関数発生器１３の出力信号と前記主蒸気圧力検出器１５の出力信号との差分データを求める減算器１４と、減算器１４から出力される差分データを弁開度制御信号に変換する比例・積分器１８と、該比例・積分器１８の出力信号をそれに応じた弁駆動信号に変換する信号切替器１９とから構成されている。
【０００６】
【発明が解決しようとする課題】
前記した従来の起動制御装置２００は、高圧タービン９を起動させるための蒸気条件作成に際しての昇温・昇圧制御を、主蒸気圧力を指標とする弁開度プログラムによって行なうので、弁開度プログラムとボイラ４への燃料投入量とによって、主蒸気圧力の昇温・昇圧時間が一義的に定まる。このため、例えばボイラ点火時においてボイラがホットモードにあるかコールドモードにあるかに拘らず、常に一定の弁開度プログラムにしたがって主蒸気圧力の昇温・昇圧が制御されるので、予定時間通りにタービンを起動することが難しいという不都合がある。また、ボイラ点火からタービン通気に至るまでのスケジュールを変更するためには、関数発生器１６に記憶された弁開度プログラムを書き替えなくてはならず、スケジュールを必要に応じて適宜変更することができないという不都合がある。
【０００７】
かかる不都合を回避し、常に主蒸気をスケジュール通り昇温・昇圧にするためには、プログラム制御によらない新たな起動制御装置の開発が不可欠である。
【０００８】
本発明は、かかる課題を解決するためになされたものであって、その目的は、主蒸気を常にスケジュール通り昇温・昇圧できる変圧貫流ボイラの起動制御装置を提供することにある。
【０００９】
【課題を解決するための手段】
本発明は、前記課題を解決するため、ボイラ点火からタービン通気に至るまでの間、変圧貫流ボイラの過熱部に設置された過熱器バイパス弁及び／又は過熱部の出口以降に設置されたタービンバイパス弁の開度を制御することで、主蒸気温度及び圧力を目標値まで目標スケジュール通りに昇温・昇圧する変圧貫流ボイラの起動制御装置において、信号発生器から入力される発電量指令値を昇圧完了目標温度に変換し、この昇圧完了目標温度とボイラ点火時における前記水壁出口のボイラ水温度との差分から目標スケジュール通りにボイラ水温度を昇温させるための昇温率を設定し、この昇温率から求められる各時間ごとの目標圧力値とその時の主蒸気圧力との差分から制御信号を得て前記過熱器バイパス弁及び／又はタービンバイパス弁の開度を制御するようにした。
【００１０】
また他の手段として、前記と同様の変圧貫流ボイラの起動制御装置において、信号発生器から入力される発電量指令値を昇圧完了目標圧力に変換し、この昇圧完了目標圧力とボイラ点火時における前記主蒸気圧力との差分から目標スケジュール通りに主蒸気圧力を昇圧させるための昇圧率を設定し、この昇圧率から求められる各時間ごとの目標圧力値とその時の主蒸気圧力との差分から制御信号を得、ボイラ点火時のボイラがホットモードにあるときには、前記過熱器バイパス弁の開度を制御することによって前記主蒸気の昇圧制御を行い、ボイラ点火時のボイラがコールドモードにあるときには、前記タービンバイパス弁の開度を制御することによって前記主蒸気の昇圧制御を行なうようにした。
【００１１】
前記第１の課題解決手段においても、主蒸気の昇温・昇圧制御を過熱器バイパス弁の開度を制御することで行なうか、タービンバイパス弁の開度を制御することで行なうかは、任意に選択できるが、過熱器のメタル保有熱の放出を極力少なくし、かつ起動時におけるボイラ出口の蒸気温度を高温に保てることから、ボイラ点火時においてボイラがホットモードにあるときには、過熱器バイパス弁の開度を制御することによって主蒸気の昇圧制御を行い、ボイラ点火時においてボイラがコールドモードにあるときには、タービンバイパス弁の開度を制御することによって主蒸気の昇圧制御を行なうことが特に好ましい。
【００１２】
【作用】
前記手段によると、発電量指令値から得られる昇圧完了目標温度とボイラ点火時における水壁出口のボイラ水温度との差分から目標スケジュール通りにボイラ水温度を昇温させるための昇温率を設定するので、ボイラ点火時においてボイラがホットモードになっているかコールドモードになっているかに関係なく、常に目標スケジュール通りの主蒸気の昇温・昇圧制御が可能になる。また、前記他の手段もこれと同様であって、発電量指令値から得られる昇圧完了目標圧力とボイラ点火時における主蒸気圧力との差分から目標スケジュール通りに主蒸気圧力を昇圧させるための昇圧率を設定するので、ボイラ点火時においてボイラがホットモードになっているかコールドモードになっているかに関係なく、常に目標スケジュール通りの主蒸気の昇温・昇圧制御が可能になる。
【００１３】
【実施例】
図１に、第１実施例に係る変圧貫流ボイラ及びその起動制御装置を示す。本実施例においても、変圧貫流ボイラについては従来技術と同一構成のものが用いられるので、重複を避けるため、対応する各装置に図４と同一の符号を付して説明を省略する。
【００１４】
本実施例の起動制御装置２０１は、図１に示すように、発電量指令信号ａを発生する信号発生器２０と、発電量指令信号ａを昇圧完了目標温度に変換する信号切替器２１と、ボイラ水壁出口のボイラ水温度を検出する温度検出器２２と、前記昇圧完了目標温度とボイラ点火時における前記水壁出口のボイラ水温度との差分信号ｂから目標スケジュール通りにボイラ水温度を昇温させるための昇温率を設定する昇温率制限器２３と、前記差分信号ｂに対するそれに好適な昇温率のテーブルが予め記憶された昇温率設定器２４と、昇温率制限器２３の出力信号ｃをその温度に相当する飽和蒸気圧力信号ｄに変換する関数発生器２５と、高圧タービン９入口の主蒸気圧力を検出する主蒸気圧力検出器２６と、前記飽和蒸気圧力信号ｄと主蒸気圧力検出器２６から出力される主蒸気圧力信号ｅとの差を求める減算器２７と、減算器２７から出力される差分信号ｆをそれに応じた弁開度信号ｇに変換する比例・積分器２８と、弁開度信号ｇを過熱器バイパス弁１０の駆動信号ｈ及び／又はタービンバイパス弁１１の駆動信号ｉに変換する信号切替器２９とから構成されている。
【００１５】
図２に、ボイラ点火、タービン通気、電力併入のタイミングと過熱器バイパス弁１０及び／又はタービンバイパス弁１１の開度との関係、それに前記タイミングと主蒸気圧力及び負荷の大きさとの関係を示す。この図から明らかなように、ボイラ点火がなされると、初期の段階では過熱器バイパス弁１０及び／又はタービンバイパス弁１１の開度が一定の変化率で大きくなり、主蒸気圧力が徐々に上昇する。主蒸気圧力が所定値に達すると、当該主蒸気圧力値を保持するように過熱器バイパス弁１０及び／又はタービンバイパス弁１１の開度が差分信号ｆの大きさ及び符号に応じて繰返し微調整され、主蒸気温度の上昇が図られる。そして、主蒸気温度及び圧力が所定の値に達した段階でタービン通気が実行され、その後の高圧タービン９の出力が安定した段階で併入が行なわれる。主蒸気温度及び圧力の上昇と共に、過熱器バイパス弁１０及び／又はタービンバイパス弁１１の開度は徐々に低下し、やがて全閉される。その後、変圧貫流ボイラが循環運転から貫流運転に切り替わり、主蒸気圧力が上昇する。併入後、高圧タービン９の負荷が徐々に高められ、発電量指令信号ａに応じた発電が行なわれる。
【００１６】
本例の起動制御装置２０１は、ボイラ点火ごとに、その時点におけるボイラ水温度を参照してそれに好適な昇温率を設定し、過熱器バイパス弁１０及び／又はタービンバイパス弁１１の開度を制御するので、ボイラ点火時においてボイラ４がホットモードになっているかコールドモードになっているかに関係なく、常に目標スケジュール通りに主蒸気を昇温・昇圧制御できる。
【００１７】
なお、主蒸気の昇温・昇圧制御を過熱器バイパス弁１０の開度制御で行なうかタービンバイパス弁１１の開度制御で行なうかは、任意に選択できるが、過熱器のメタル保有熱の放出を極力少なくし、かつ起動時におけるボイラ出口の蒸気温度を高温に保てることから、ボイラ点火時においてボイラ４がホットモードにあるときには、過熱器バイパス弁１０の開度を制御することによって行ない、ボイラ点火時においてボイラ４がコールドモードにあるときには、タービンバイパス弁１１の開度を制御することによって行なうことが特に好ましい。
【００１８】
図３に、第２実施例に係る変圧貫流ボイラ及びその起動制御装置を示す。図３において、符号３１は信号切替器、符号３２は昇圧率制限器、符号３３は昇圧率設定器を示し、その他前出の図１と対応する各装置には、それと同一の符号が表示されている。
【００１９】
本実施例の起動制御装置２０２は、図３に示すように、発電量指令信号ａを発生する信号発生器２０と、発電量指令信号ａを昇圧完了目標圧力に変換する信号切替器３１と、高圧タービン９入口の主蒸気圧力を検出する主蒸気圧力検出器２６と、前記昇圧完了目標圧力とボイラ点火時における前記主蒸気圧力との差分信号ｊから目標スケジュール通りに主蒸気圧力を昇圧させるための昇圧率を設定する昇圧率制限器３２と、前記差分信号ｊに対するそれに好適な昇圧率のテーブルが予め記憶された昇圧率設定器３３と、昇温率制限器３２の出力信号ｋと主蒸気圧力検出器２６から出力される主蒸気圧力信号ｌとの差を求める減算器２７と、減算器２７から出力される差分信号ｍをそれに応じた弁開度信号ｇに変換する比例・積分器２８と、弁開度信号ｇを過熱器バイパス弁１０の駆動信号ｈ及び／又はタービンバイパス弁１１の駆動信号ｉに変換する信号切替器２９とから構成されている。
【００２０】
本例の起動制御装置は、発電量指令値ａから得られる昇圧完了目標圧力とボイラ点火時における主蒸気圧力との差分から目標スケジュール通りに主蒸気圧力を昇圧させるための昇圧率を設定するので、ボイラ点火時においてボイラがホットモードになっているかコールドモードになっているかに関係なく、常に目標スケジュール通りの主蒸気の昇温・昇圧制御が可能になる。本実施例の場合にも、主蒸気の昇温・昇圧制御を過熱器バイパス弁１０の開度制御で行なうかタービンバイパス弁１１の開度制御で行なうかは任意に選択できるが、過熱器８のメタル保有熱の放出を極力少なくし、かつ起動時におけるボイラ４出口の蒸気温度を高温に保てることから、ボイラ点火時においてボイラ４がホットモードにあるときには、過熱器バイパス弁１０の開度を制御することによって行ない、ボイラ点火時においてボイラ４がコールドモードにあるときには、タービンバイパス弁１１の開度を制御することによって行なうことが特に好ましい。
【００２１】
本例の起動制御装置は、前記第１実施例と同様の効果を奏するほか、発電量指令値ａから昇圧完了目標圧力を得て、直接ボイラ点火時における主蒸気圧力と比較するようにしたので、回路構成を簡略化できるという効果がある。
【００２２】
【発明の効果】
以上説明したように、本発明によれば、ボイラ点火時においてボイラがホットモードになっているかコールドモードになっているかに関係なく、常に目標スケジュール通りの主蒸気の昇温・昇圧制御が可能になるので、電力の併入遅れを防止できる。また、昇温率設定器又は昇圧率設定器のデータを書き替えるだけでボイラ点火からタービン通気に至るまでのスケジュールを適宜変更できるので、気候等にあわせて決め細かいスケジュール調整を行なうことができ、燃料の無駄を防止できる。
【図面の簡単な説明】
【図１】第１実施例に係る変圧貫流ボイラ及びその起動制御装置を示す説明図である。
【図２】第１実施例に係る変圧貫流ボイラの動作説明図である。
【図３】第２実施例に係る変圧貫流ボイラ及びその起動制御装置を示す説明図である。
【図４】従来例に係る変圧貫流ボイラ及びその起動制御装置を示す説明図である。
【符号の説明】
１００変圧貫流ボイラ
２０１，２０２起動制御装置
４ボイラ
８過熱器
９高圧タービン
１０過熱器バイパス弁
１１タービンバイパス弁
２０信号発生器
２１信号切替器
２２温度検出器
２３昇温率制限器
２４昇温率設定器
２５関数発生器
２６主蒸気圧力検出器
２７減算器
２８比例・積分器
２９信号切替器
３１信号切替器
３２昇圧率制限器
３３昇圧率設定器[0001]
[Industrial applications]
The present invention relates to a variable-pressure once-through boiler start-up control device for controlling a temperature rising / boosting time from boiler ignition to turbine ventilation according to a target schedule.
[0002]
[Prior art]
In general, a once-through boiler operated in a thermal power plant is stopped at night when the power consumption decreases, and is started at the time when the power consumption increases the next morning. The startup of the variable-pressure once-through boiler takes into account the time required to raise the main steam temperature and pressure to the values required for turbine startup from the time of boiler ignition, and consider this time earlier than the time when power supply is required. Done. Therefore, it is particularly required that the temperature rise and pressure rise of the boiler be performed according to the originally scheduled schedule in order to meet the time at which the power supply is required. In addition, it is preferable that the time required to raise and lower the temperature of the boiler reaches a predetermined value in a short time as much as possible in order to reduce fuel consumption.
[0003]
FIG. 4 shows a conventionally known variable-pressure once-through boiler and its startup control device. As shown in this figure, the variable-pressure once-through boiler 100 includes a feedwater pump 1, a high-pressure feedwater heater 2 for heating the feedwater from the feedwater pump 1, and an economizer for preheating the feedwater by using the residual heat of the flue gas. 3, a boiler 4 having a water wall structure into which water supplied from the economizer 3 is introduced, a steam-water separator 5 for separating steam generated in the boiler 4 from steam and water, and storing the separated boiler water. A water storage tank 6, a boiler recirculation pump 7 for sending water in the water storage tank 6 to the economizer 3, a superheater 8 that superheats the saturated steam separated by the steam separator 5 to superheat steam, A high-pressure turbine 9 rotating by using the superheated steam from the heater 8 as a drive source, a superheater bypass valve 10 installed in a superheater bypass line connecting the superheater 8 and the condenser, and an outlet pipe of the superheater 8 Turbine installed in a turbine bypass line that communicates with the condenser And a path valve 11.
[0004]
On the other hand, the start control device 200 includes a main steam pressure detector 15 for detecting the main steam pressure of the boiler 100, and a function generator for outputting a valve opening degree program signal corresponding to an output signal of the main steam pressure detector 15. 16, a change rate limiter 17 for setting a change rate of the valve opening degree from a valve opening degree program signal output from the function generator 16, and a valve drive signal corresponding to the output signal of the change rate limiter 17 , And a signal switch 19 for converting the signal into a signal. According to the startup control device 200, the opening degrees of the superheater bypass valve 10 and the turbine bypass valve 11 are program-controlled by a valve opening degree program using the main steam pressure as an index, and the temperature rise of the main steam that starts the high-pressure turbine 9 -A boost is performed.
[0005]
Reference numeral 300 in the figure is a control device of the superheater bypass valve 10 and the turbine bypass valve 11 after the start of turbine ventilation, and a signal generator 12 for generating a power generation amount command signal and a power generation amount command signal. A function generator 13 for converting to a corresponding main steam target pressure, a subtractor 14 for obtaining difference data between an output signal of the function generator 13 and an output signal of the main steam pressure detector 15, and an output from the subtractor 14. The proportional / integrator 18 converts the differential data to a valve opening control signal, and a signal switch 19 converts an output signal of the proportional / integrator 18 into a corresponding valve drive signal.
[0006]
[Problems to be solved by the invention]
The above-described conventional start-up control device 200 performs the temperature increase / step-up control at the time of creating the steam conditions for starting the high-pressure turbine 9 by using the valve opening degree program using the main steam pressure as an index. The time for raising and lowering the main steam pressure is uniquely determined by the amount of fuel supplied to the boiler 4. For this reason, for example, at the time of boiler ignition, regardless of whether the boiler is in the hot mode or the cold mode, the temperature rise and pressure increase of the main steam pressure are always controlled according to a fixed valve opening program, so that the scheduled time However, there is a disadvantage that it is difficult to start the turbine. In addition, in order to change the schedule from boiler ignition to turbine ventilation, the valve opening program stored in the function generator 16 must be rewritten, and the schedule must be changed as necessary. There is a disadvantage that you can not.
[0007]
In order to avoid such inconveniences and to always raise and raise the temperature of the main steam as scheduled, it is essential to develop a new start-up control device that does not rely on program control.
[0008]
The present invention has been made to solve such a problem, and an object of the present invention is to provide a start-up control device for a variable-pressure once-through boiler that can always raise and raise the temperature of main steam as scheduled.
[0009]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention provides a superheater bypass valve installed in a superheated section of a variable-pressure once-through boiler and / or a turbine bypass installed after an outlet of the superheated section from boiler ignition to turbine ventilation. By controlling the opening of the valve, in the start-up control device of the variable-pressure once-through boiler, which raises and raises the main steam temperature and pressure to target values according to the target schedule, the power generation command value input from the signal generator is boosted. The target temperature is converted to the completion target temperature, and the temperature rise rate for raising the boiler water temperature according to the target schedule is set from the difference between the boosting completion target temperature and the boiler water temperature at the water wall outlet at the time of boiler ignition. A control signal is obtained from the difference between the target pressure value for each time obtained from the temperature increase rate and the main steam pressure at that time to open the superheater bypass valve and / or the turbine bypass valve. It was to control the.
[0010]
As another means, in the start-up control device for a variable-pressure once-through boiler similar to the above, the power generation amount command value input from the signal generator is converted into a boost completion target pressure, and the boost completion target pressure and the boiler ignition From the difference with the main steam pressure, a pressure increase rate for setting the main steam pressure to be increased according to the target schedule is set, and the control signal is obtained from the difference between the target pressure value for each hour obtained from the pressure increase rate and the main steam pressure at that time. When the boiler at the time of boiler ignition is in the hot mode, the booster control of the main steam is performed by controlling the opening of the superheater bypass valve, and when the boiler at the time of the boiler ignition is in the cold mode, The control of the pressure of the main steam is performed by controlling the opening of the turbine bypass valve .
[0011]
Also in the first means for solving the problems , it is optional whether the temperature rise / pressure control of the main steam is performed by controlling the opening of the superheater bypass valve or by controlling the opening of the turbine bypass valve. However, since the release of the metal possessed heat of the superheater is reduced as much as possible and the steam temperature at the boiler outlet at the time of startup can be kept high, when the boiler is in the hot mode at the time of boiler ignition, the superheater bypass valve It is particularly preferable to control the pressure of the main steam by controlling the opening of the main steam, and to control the pressure of the main steam by controlling the opening of the turbine bypass valve when the boiler is in the cold mode at the time of boiler ignition. .
[0012]
[Action]
According to the above-mentioned means, a heating rate for raising the boiler water temperature according to the target schedule is set from the difference between the boosting completion target temperature obtained from the power generation amount command value and the boiler water temperature at the water wall outlet at the time of boiler ignition. Therefore, regardless of whether the boiler is in the hot mode or the cold mode when the boiler is ignited, it is possible to always control the temperature rise and pressure of the main steam according to the target schedule. Further, the other means is the same as the above, and the booster for raising the main steam pressure according to the target schedule is obtained from the difference between the boost completion target pressure obtained from the power generation amount command value and the main steam pressure at the time of boiler ignition. Since the rate is set, the temperature rise / pressure control of the main steam can always be performed according to the target schedule, regardless of whether the boiler is in the hot mode or the cold mode at the time of boiler ignition.
[0013]
【Example】
FIG. 1 shows a variable-pressure once-through boiler according to a first embodiment and a startup control device thereof. Also in this embodiment, since the same configuration as that of the prior art is used for the variable-pressure once-through boiler, corresponding devices are denoted by the same reference numerals as in FIG.
[0014]
As shown in FIG. 1, the start control device 201 of the present embodiment includes a signal generator 20 that generates a power generation amount command signal a, a signal switch 21 that converts the power generation amount command signal a into a boost completion target temperature, A temperature detector 22 for detecting a boiler water temperature at a boiler water wall outlet, and a boiler water temperature is raised according to a target schedule from a difference signal b between the boost completion target temperature and the boiler water temperature at the water wall outlet at the time of boiler ignition. A heating rate limiting device 23 for setting a heating rate for heating; a heating rate setting device 24 in which a table of a heating rate suitable for the difference signal b is stored in advance; , A function generator 25 for converting the output signal c into a saturated steam pressure signal d corresponding to the temperature, a main steam pressure detector 26 for detecting the main steam pressure at the inlet of the high-pressure turbine 9, and the saturated steam pressure signal d. Main steam pressure detection A subtractor 27 for obtaining a difference from the main steam pressure signal e output from the device 26, a proportional / integrator 28 for converting the difference signal f output from the subtracter 27 into a corresponding valve opening signal g, A signal switch 29 for converting the valve opening signal g into a drive signal h for the superheater bypass valve 10 and / or a drive signal i for the turbine bypass valve 11.
[0015]
FIG. 2 shows the relationship between the timing of boiler ignition, turbine ventilation, and power supply and the degree of opening of the superheater bypass valve 10 and / or the turbine bypass valve 11, and the relationship between the timing and the magnitude of the main steam pressure and load. Show. As is apparent from this figure, when the boiler is ignited, the opening of the superheater bypass valve 10 and / or the turbine bypass valve 11 increases at a constant rate in the initial stage, and the main steam pressure gradually increases. I do. When the main steam pressure reaches a predetermined value, the opening degree of the superheater bypass valve 10 and / or the turbine bypass valve 11 is repeatedly finely adjusted according to the magnitude and sign of the difference signal f so as to maintain the main steam pressure value. As a result, the main steam temperature is increased. Then, when the main steam temperature and the pressure reach the predetermined values, turbine ventilation is performed, and after that, when the output of the high-pressure turbine 9 is stabilized, the entrainment is performed. As the main steam temperature and pressure increase, the opening degree of the superheater bypass valve 10 and / or the turbine bypass valve 11 gradually decreases, and is eventually fully closed. Thereafter, the variable-pressure once-through boiler switches from circulation operation to once-through operation, and the main steam pressure rises. After the insertion, the load on the high-pressure turbine 9 is gradually increased, and power generation is performed according to the power generation amount command signal a.
[0016]
The startup control device 201 of the present embodiment refers to the boiler water temperature at that time and sets a suitable heating rate for each boiler ignition, and determines the opening degree of the superheater bypass valve 10 and / or the turbine bypass valve 11. Since the control is performed, the temperature of the main steam can be constantly raised and raised according to the target schedule regardless of whether the boiler 4 is in the hot mode or the cold mode when the boiler is ignited.
[0017]
It should be noted that it is possible to arbitrarily select whether the control of the temperature rise and pressure increase of the main steam is performed by controlling the opening of the superheater bypass valve 10 or by controlling the opening of the turbine bypass valve 11. Is reduced as much as possible, and the steam temperature at the boiler outlet at the time of start-up can be kept high. Therefore, when the boiler 4 is in the hot mode at the time of boiler ignition, the boiler 4 is controlled by controlling the opening of the superheater bypass valve 10. When the boiler 4 is in the cold mode at the time of ignition, it is particularly preferable to control the opening degree of the turbine bypass valve 11.
[0018]
FIG. 3 shows a variable-pressure once-through boiler and a start-up control device thereof according to a second embodiment. In FIG. 3, reference numeral 31 denotes a signal switch, reference numeral 32 denotes a boosting rate limiter, and reference numeral 33 denotes a boosting rate setting device. Other devices corresponding to those in FIG. ing.
[0019]
As shown in FIG. 3, the start control device 202 of the present embodiment includes a signal generator 20 that generates a power generation amount command signal a, a signal switch 31 that converts the power generation amount command signal a into a boost completion target pressure, A main steam pressure detector 26 for detecting a main steam pressure at the inlet of the high-pressure turbine 9 and a main steam pressure is raised according to a target schedule from a difference signal j between the target pressure for completion of pressure increase and the main steam pressure at the time of boiler ignition. A boosting rate limiter 32 for setting the boosting rate, a boosting rate setter 33 in which a table of a suitable boosting rate for the difference signal j is stored in advance, an output signal k of the temperature increasing rate limiter 32 and the main steam. A subtractor 27 for obtaining a difference from the main steam pressure signal 1 output from the pressure detector 26, and a proportional / integrator 28 for converting the difference signal m output from the subtracter 27 into a corresponding valve opening signal g. And the valve And a signal switch 29 for converting the degrees signal g to the drive signal i of the drive signals h and / or the turbine bypass valve 11 of the superheater bypass valve 10.
[0020]
The startup control device of the present embodiment sets the boost rate for increasing the main steam pressure according to the target schedule from the difference between the boost completion target pressure obtained from the power generation amount command value a and the main steam pressure at the time of boiler ignition. In addition, regardless of whether the boiler is in the hot mode or the cold mode at the time of boiler ignition, it is possible to always control the temperature rise and pressure of the main steam according to the target schedule. Also in the case of the present embodiment, it is possible to arbitrarily select whether the temperature rise / pressure control of the main steam is performed by controlling the opening of the superheater bypass valve 10 or by controlling the opening of the turbine bypass valve 11. When the boiler 4 is in the hot mode at the time of the boiler ignition, the opening of the superheater bypass valve 10 is reduced by minimizing the release of the heat possessed by the metal and keeping the steam temperature at the outlet of the boiler 4 at a high temperature at the time of startup. It is particularly preferable to perform the control by controlling the opening of the turbine bypass valve 11 when the boiler 4 is in the cold mode at the time of boiler ignition.
[0021]
The startup control device of the present embodiment has the same effects as the first embodiment, and also obtains the boosting completion target pressure from the power generation amount command value a and compares it with the main steam pressure at the time of direct boiler ignition. This has the effect of simplifying the circuit configuration.
[0022]
【The invention's effect】
As described above, according to the present invention, it is possible to always control the temperature and pressure of the main steam according to the target schedule, regardless of whether the boiler is in the hot mode or the cold mode at the time of boiler ignition. Therefore, it is possible to prevent the delay of power supply. In addition, since the schedule from boiler ignition to turbine ventilation can be changed as appropriate simply by rewriting the data of the heating rate setting device or the boosting rate setting device, it is possible to make a detailed schedule adjustment according to the climate etc. Fuel waste can be prevented.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a variable-pressure once-through boiler and a startup control device thereof according to a first embodiment.
FIG. 2 is an operation explanatory diagram of the variable-pressure once-through boiler according to the first embodiment.
FIG. 3 is an explanatory diagram showing a variable-pressure once-through boiler and a startup control device thereof according to a second embodiment.
FIG. 4 is an explanatory diagram showing a variable-pressure once-through boiler and a startup control device thereof according to a conventional example.
[Explanation of symbols]
REFERENCE SIGNS LIST 100 Transformer once-through boilers 201, 202 Start-up control device 4 Boiler 8 Superheater 9 High-pressure turbine 10 Superheater bypass valve 11 Turbine bypass valve 20 Signal generator 21 Signal switch 22 Temperature detector 23 Heating rate limiter 24 Heating rate setting Unit 25 Function generator 26 Main steam pressure detector 27 Subtractor 28 Proportional / integrator 29 Signal switch 31 Signal switch 32 Step-up rate limiter 33 Step-up rate setting unit

Claims

By controlling the opening degree of the superheater bypass valve installed in the superheating section of the variable-pressure once-through boiler and / or the turbine bypass valve installed after the exit of the superheating section from the boiler ignition to the turbine ventilation, In a start-up control device of a variable-pressure once-through boiler that raises and raises steam temperature and pressure to target values according to a target schedule, a power generation command value input from a signal generator is converted into a boosting completion target temperature. From the difference between the temperature and the boiler water temperature at the water wall outlet at the time of boiler ignition, a heating rate for raising the boiler water temperature according to a target schedule is set, and a target for each hour obtained from the heating rate is set. A pressure control unit that obtains a control signal from a difference between a pressure value and a main steam pressure at that time to control an opening degree of the superheater bypass valve and / or the turbine bypass valve. Boiler startup control device.

By controlling the opening degree of the superheater bypass valve installed in the superheated section of the variable-pressure once-through boiler and / or the turbine bypass valve installed after the outlet of the superheated section during the period from boiler ignition to turbine ventilation, In a start-up control device of a variable-pressure once-through boiler that raises and raises steam temperature and pressure to target values according to a target schedule, a power generation command value input from a signal generator is converted into a boosting completion target pressure. From the difference between the pressure and the main steam pressure at the time of boiler ignition, a boost rate for increasing the main steam pressure according to a target schedule is set, and a target pressure value for each time obtained from the boost rate and the main steam at that time are set. obtain a control signal from the difference between the pressure, when the boiler at the boiler ignition is in the hot mode, before by controlling the opening degree of the superheater bypass valve Performs boost control of the main steam, when the boiler at the boiler ignition is in cold mode, the activation of the transformer once-through boiler, characterized by performing step-up control of the main steam by controlling the degree of opening of the turbine bypass valve Control device.

2. The startup control device for a variable- pressure once- through boiler according to claim 1, wherein when the boiler is in a hot mode at the time of boiler ignition, the main steam pressure is increased by controlling an opening degree of the superheater bypass valve. A startup control apparatus for a variable-pressure once-through boiler, wherein when the boiler at the time of ignition is in a cold mode, the main steam is boosted by controlling an opening of the turbine bypass valve.