JP4095829B2

JP4095829B2 - Char circulation type coal gasification power plant system

Info

Publication number: JP4095829B2
Application number: JP2002146031A
Authority: JP
Inventors: 克彦横濱; 雄一郎北川; 泰成柴田
Original assignee: Mitsubishi Heavy Industries Ltd
Current assignee: Mitsubishi Heavy Industries Ltd
Priority date: 2002-05-21
Filing date: 2002-05-21
Publication date: 2008-06-04
Anticipated expiration: 2022-05-21
Also published as: JP2003336081A

Description

【０００１】
【発明の属する技術分野】
本発明は、石炭ガス化炉で発生させた石炭（微粉炭）の粗ガスをガス精製設備で精製して燃料ガスを発生させ、その燃料ガスをガスタービンで燃焼させて発電を行う石炭ガス化発電プラントシステムに係り、特に前記ガス化炉で発生した石炭未燃分（以後チャーという）をガス化炉に戻し、燃焼効率の向上を図ったチャー循環型の石炭ガス化発電プラントシステムに関する。
【０００２】
【従来の技術】
一般に、石炭ガス化複合発電プラントは、微粉炭とガス化剤とを反応させて可燃性ガスを生成する石炭ガス化炉が設けられ、ガス化炉で発生させた石炭の粗ガスをガス精製設備で精製して燃料ガスを発生させ、その燃料ガスをガスタービンで燃焼させると共に、ガスタービンで燃焼させた排ガスの排熱及びガス化炉設備で蒸気を発生させ、その蒸気で蒸気タービンを駆動し発電するように構成されており、又近年前記ガス化炉で発生した熱分解ガスをボイラ等により冷却後サイクロン等で微粉固形状の石炭未燃分（チャー）をサイクロンで捕捉して石炭ガス化炉に戻し、熱効率の向上を図っていた。
【０００３】
係る技術を図４に基づいて説明するに、図中１は、コンバスタ１ａとリダクタ１ｂからなる空気吹き加圧二段噴流床式ガス化炉で、コンバスタ１ａ内に微粉炭（石炭）とチャーと空気及び必要に応じて酸素富化空気とを投入して高温燃焼した後、更にその上方のリダクタ１ｂ内に更に微粉炭（石炭）を投入してコンバスタ１ａの高温燃焼を利用して乾留ガス化させる。ガス化したＣＯやＨ₂等の生成ガスは、熱回収ボイラ等の冷却器１２により冷却された後、ポーラスフィルタやサイクロンでチャーを回収分離した後、ガス熱交換器２１、ＣＯＳ変換器２２、ガス熱交換器２３を経てガス冷却塔１４及びガス洗浄塔１５からなるアンモニア除去装置でアンモニアを除去した後、Ｈ₂Ｓ吸収塔１６に送られ、Ｈ₂Ｓを除去する。
Ｈ₂Ｓ吸収塔１６では、吸収液により粗生成ガス中のＨ₂Ｓ、ＣＯＳ等の硫黄化合物がガスタ−ビン１７の許容濃度以下まで除去される。
【０００４】
一方Ｈ₂Ｓ吸収塔１６で精製されたガスはスチーム熱交換器２４、ガス熱交換器２３及びガス熱交換器２１で順次昇温してガスタ−ビン１７に送られ、発電が行われ、一方ガスタ−ビン１７からの燃焼排ガスは不図示の排熱回収ボイラにて冷却されると同時にスチーム熱交換器２４で昇温された高圧蒸気を回収し、ここで得られた蒸気は不図示の蒸気タービンに送られ、発電が行われる。
【０００５】
又Ｈ₂Ｓ吸収塔１６でＨ₂Ｓ等の硫黄化合物を吸収した吸収液は吸収再生塔１８に送られ、吸収液再生加熱器１９で加熱することで吸収しているＨ₂Ｓを脱離し再生される。
【０００６】
しかしながらこのようなチャー再循環型の石炭ガス化炉で生成した燃料ガスの発熱量は、発生する石炭未燃分（チャー）の投入量の変動によって変動していた。
一般に、チャー投入量は循環系のホッパ重量を一定に保つか又が発熱量をある程度一定に保つように、重量制御と組み合わせて制御を行っているが、ホッパの重量の変動の制約又はチャーをガス化炉に噴出して燃焼する際の、バーナの一時的な詰まり若しくはホッパよりガス化炉までの搬送路における流量変動によってチャー投入量が変動することを防止することは極めて困難であった。
このチャーの変動によって生成ガスの発熱量が変動し、結果としてガスタービン発電機の出力すなわちプラント負荷が変動するために安定した発電出力が得られないという欠点を有していた。
【０００７】
又チャー再循環するシステムとしては、例えば特開２０００−３２８０７４が開示されている。
かかる技術は微粉炭とガス化剤とを反応させて可燃性ガスを生成する石炭ガス化炉が設けられ、可燃性ガス（熱分解ガス）生成時にチャーが発生するため、サイクロンとフィルタで回収して石炭ガス化炉にリサイクルされている。このような石炭ガス化システムにおいて、チャー回収後の可燃性ガスの一部を取り出して熱交換器で加熱する。そして、その加熱後の可燃性ガスを搬送用ガスとして用いて、微粉炭およびチャーを石炭ガス化炉に供給するものである。
【０００８】
しかしながら係る技術においては、本発明の目的は、搬送用ガスが粉体燃料と混合したときにガス中の水分の凝縮を防ぎ、粉体燃料の搬送を安定して行うことのできるものであるが、チャーの変動によって発熱量が変動することは何等考慮されていない。特にチャーの搬送ガスとして可燃性ガスを用いるために、発熱量の変動が更に大きくなる。
【０００９】
【発明が解決しようとする課題】
本発明は、かかる従来技術の課題に鑑み、ガス発熱量及びガスタービン等の出力の安定化を図るために、石炭ガス化炉より得られる可燃性ガスのガス発熱量やガスタービン等の出力等の二次的な変動に基づいて石炭ガス化炉に投入される石炭（微粉炭）を制御するのではなく、チャー投入量そのものから補正して石炭量を増加させる。又炉内空気比を一定に保つことから本質的に石炭ガス化炉内の発熱量を一定に保ち、結果としてガス発熱量及びガスタービン等の出力の安定化を図ることを目的とする。
本発明の他の目的は起動時にチャーが発生し、ホッパに蓄積するまでに、石炭量を増加させ発熱量及び出力を一定に保つことにある。
【００１０】
【課題を解決するための手段】
本発明はかかる課題を解決するために、石炭（微粉炭）ガス化炉設備で発生させた石粗可燃性ガスをガス精製設備で精製して燃料ガスを発生させ、その燃料ガスをガスタービンで燃焼させて発電を行うとともに、前記粗ガスより固気分離器を介して石炭未燃分（以後チャーという）を分離して搬送路を介してガス化炉に戻すように構成したチャー循環型の石炭ガス化発電プラントシステムにおいて、
前記石炭ガス化炉起動時に、チャーの循環動作を行うことなく、石炭投入量を増加させて運転し、前記供給装置にチャーが所定量蓄積するまでに、石炭投入量の増加を維持させ、前記チャー供給装置にチャーが所定量蓄積した段階で前記ガス化炉にチャーを戻すチャーの循環制御を開始する第１のステップと、
前記第１のステップ終了後、前記チャーの循環制御でチャー戻し量若しくはその変動量を検知しつつ空気、酸素等の酸化剤の流量は一定とし、石炭量とチャー量を合算した可燃分に対する理論燃焼空気量と投入酸素量の比（炉内空気比）が一定になるように、石炭投入量を制御させることを特徴とする。
このように、石炭ガス化炉から発生する生成ガス発熱量を一定に保つためには、前記ガス化炉に投入している空気、酸素等の酸化剤の流量は一定とし、投入石炭量のみを増減制御させる。
これにより石炭ガス化炉より得られる可燃性ガスのガス発熱量やガスタービン等の出力等の二次的な変動に基づいて石炭ガス化炉に投入される石炭投入量を制御するのではなく、チャー投入量そのものから補正して石炭量を増加させるために、投入制御量が精度良く確実に行われ、且つタイム遅れがない。
【００１１】
特に、本発明は、炉内空気比を一定に保つことから本質的に石炭ガス化炉内の発熱量を一定に保ち、結果として生成ガス発熱量及びガスタービン等の出力の安定化を図ることが出来る。
【００１２】
そしてこのような発明の具体的装置は、前記固気分離器で回収したチャーを一時貯留するチャー供給装置を介して搬送路より前記ガス化炉にチャーを戻すように構成するとともに、前記第１のステップ終了後、前記供給装置の重量変化より演算して得られた前記搬送路を流れるチャー流量変化や、前記搬送路のチャー密度と流速から演算して得られたチャー流量変化や前記搬送路の差圧から演算して得られたチャー流量変化に基づいて、投入すべき石炭量を制御すればよい。
【００１３】
又本発明は、第１のステップで前記石炭ガス化炉起動時に、チャーの循環動作を行うことなく、石炭投入量を増加させて運転し、前記供給装置にチャーが所定量蓄積するまでに、石炭投入量の増加を維持させ、所定量蓄積した段階でチャーの循環制御を開始することを特徴とする。
【００１４】
従来の技術では、起動時には石炭を定常量投入してもチャーが発生していないために、前記供給装置（ホッパ）にチャーが蓄積するまで、石炭ガス化炉内の発熱量は減少し、結果としてガス発熱量及びガスタービン等の出力が起動時に不安定化するが、本発明によればチャーの循環量が安定するまで石炭量を増加させ結果として炉内より発生する可燃ガスの発熱量及び出力を一定に保つことが出来る。
このような発明は前記固気分離器で回収したチャーを一時貯留するチャー供給装置を介して前記ガス化炉にチャーを戻す搬送路を設けるとともに、前記第１のステップで、チャー供給装置内のチャー重量を検知して所定量のチャー蓄積を判断するように構成すればよい。
【００１５】
【発明の実施の形態】
以下、本発明を図に示した実施例を用いて詳細に説明する。但し、この実施例に記載される構成部品の寸法、形状、その相対配置などは特に特定的な記載がない限り、この発明の範囲をそれのみに限定する趣旨ではなく単なる説明例に過ぎない。
図１は本発明の実施例に係るチャー循環経路を示す要部構成図で、図中１は、コンバスタ１ａとリダクタ１ｂからなる空気吹き加圧二段噴流床式ガス化炉で、コンバスタ１ａ内に微粉炭（石炭）とチャーと空気及び必要に応じて酸素富化空気とを投入して高温燃焼した後、更にその上方のリダクタ１ｂ内に更に微粉炭（石炭）を投入してコンバスタ１ａの高温燃焼を利用して乾留ガス化させる。４０及び４１はブロワである。そしてガス化したＣＯやＨ₂等の生成ガスは、熱回収ボイラ等の冷却器１２により冷却された後、ポーラスフィルタやサイクロン等のチャー回収装置１３でチャーを回収分離した後、前記した後流側に導かれ、精製されたガスはガスタ−ビンに送られ、所定の発電が行われるとともに、ガスタ−ビンからの燃焼排ガスは不図示の排熱回収ボイラにて冷却されると同時に高圧蒸気を回収し、蒸気タービンに送られ、発電が行われる。
【００１６】
一方、チャー回収装置１３で回収分離されたチャーは搬送管８及び搬送管８に設けたベンチュリーフィーダ等の粉体搬送機７によりイナートガス等を利用してガス化炉１内に戻される。
かかる構成までは公知である。
【００１７】
そして本発明は図１（Ａ）に示すように、前記チャー供給装置としてのホッパ１０にロードセル２０を設け、ホッパ１０に一次貯留されているチャーの重量変化（重量／時間）を検知しているとともに、前記搬送管８の途中に差圧計５を設け、搬送管８を流れるチャーの差圧を測定してチャー流量を演算している。
係る実施例によれば、図２（Ａ）に示すようにチャー変動検知回路３で、ロードセル２０から取り込んだ、ホッパ１０に一次貯留されているチャーの重量変化より差圧計５の差圧により得られる搬送管８内を流れるチャー気混合流の流量を補正して、サンプリング間隔毎の石炭ガス化炉に戻されるチャー重量が求められる。
そして石炭指令回路４において前記チャー戻し重量を差分器３２で基準チャー設定値から引いて変動値を求め、その変動重量に見合う等価エネルギ分に対応する石炭投入量の増減量を差分器３３により石炭投入基準量から引いて、石炭投入量の増減制御を行う。この場合、石炭ガス化炉内の発熱量を一定に保つためには、前記ガス化炉１に投入している空気、酸素等の酸化剤の流量は一定とし、投入石炭量のみを増減制御させる。この結果図３（Ａ）に示すように、チャー投入量の変動の等価エネルギに見合った石炭量の増減制御が出来るために、投入制御量が精度良く確実に行われ、且つタイム遅れがない。
【００１８】
尚、前記チャー戻し量を若しくはその変動量を検知し、石炭量とチャー量を合算した可燃分に対する理論燃焼空気量と投入酸素量の比（炉内空気比）が一定になるように、石炭投入量を制御させるのがよく、このため場合によっては空気量の制御も必要となる場合があるが制御が煩雑化するので石炭量だけの増減制御を行う。
これにより炉内空気比を一定に保つことから本質的に石炭ガス化炉内の発熱量を一定に保ち、結果としてガス発熱量及びガスタービン等の出力の安定化を図ることが出来る。
【００１９】
さて、前記石炭ガス化炉１起動時には、従来は石炭を定常量投入しているために、ホッパ１０内にチャーが貯留されていないために、図３（Ｂ）の（Ｓ１）に示すように、前記供給装置（ホッパ１０）にチャーが蓄積するまで、石炭ガス化炉内の発熱量は減少し、結果としてガス発熱量及びガスタービン等の出力が起動時に不安定化する。
そこで前記チャー供給装置としてのホッパ１０に設けたロードセル２０により、ホッパ１０に一次貯留されているチャーの重量を検知し、起動回路にて前記石炭ガス化炉起動時に、チャーの循環動作を行うことなく、石炭投入量を増加させて運転し、前記供給装置にチャーが所定量蓄積するまでに、石炭投入量の増加を維持させ、所定量蓄積した段階でチャーの循環制御を開始するのがよい。
【００２０】
すなわち図２（Ｂ）及び図３（Ｂ）（２）に示すように、ガス化炉１の起動（Ｓ１）後、石炭投入量を、定常投入量（１００％）１に対し、４０％増加（Ｓ２）した状態でガス化炉１の運転を行い、その間ホッパ１０内のチャー重量を測定（Ｓ３）してホッパ内のチャー重量が基準値に達した段階（Ｓ４）で、チャーの投入を開始（Ｓ５）し、石炭量とチャー量を合算した可燃分に対する理論燃焼空気量と投入酸素量の比（炉内空気比）が一定になるように、石炭投入量を制御させる。そして石炭が１００％、チャーが４０％の定常状態に移行した後、図３（Ａ）の制御を続ける（Ｓ６）。
前記実施例によればチャーの循環量が安定するまで石炭量を増加させ結果として炉内より発生する可燃ガスの発熱量及び出力を一定に保つことが出来る。
【００２１】
【発明の効果】
以上記載のごとく本発明によれば、ガス発熱量及びガスタービン等の出力の安定化を図るために、石炭ガス化炉より得られる可燃性ガスのガス発熱量やガスタービン等の出力等の二次的な変動に基づいて石炭ガス化炉に投入される石炭（微粉炭）を制御するのではなく、チャー投入量そのものから補正して石炭量を増加させることができる。特に石炭ガス化炉から発生する生成ガス発熱量を一定に保つためには、前記ガス化炉に投入している空気、酸素等の酸化剤の流量は一定とし、投入石炭量のみを増減制御させて炉内空気比を一定に保つことから本質的に石炭ガス化炉内の発熱量を一定に保ち、結果としてガス発熱量及びガスタービン等の出力の安定化を図ることが出来る。
又本発明によれば起動時にチャーが発生し、ホッパに蓄積するまでに、石炭量を増加させ発熱量及び出力を一定に保つことが出来る。
【図面の簡単な説明】
【図１】本発明の実施例に係るチャー循環経路を示す要部構成図で、（Ａ）は第１実施例、（Ｂ）は第２実施例である。
である。
【図２】（Ａ）は図１の作用を示すブロック図で、運転状態を示す。（Ｂ）は図１の起動時の流れを示すフロー図である。
【図３】（A）は図１の実施例における運転状態の石炭とチャーの投入量を示すグラフ図、（Ｂ）の（１）は従来技術の起動時の石炭とチャーの投入量を示すグラフ図、（Ｂ）の（２）は実施例の石炭とチャーの投入量を示すグラフ図である。
【図４】従来技術にかかる図１対応の石炭ガス化複合発電システムの全体図である。
【符号の説明】
１ガス化炉
１ａコンバスタ
１ｂリダクタ
３チャー変動検知回路
４石炭投入量指令回路
５差圧計
１０ホッパ
１２チャー回収装置
２０ロードセル
５０流量計[0001]
BACKGROUND OF THE INVENTION
The present invention relates to coal gasification in which crude gas of coal (pulverized coal) generated in a coal gasification furnace is refined with a gas purification facility to generate fuel gas, and the fuel gas is burned with a gas turbine to generate power. More particularly, the present invention relates to a char circulation type coal gasification power plant system in which unburned coal (hereinafter referred to as char) generated in the gasification furnace is returned to the gasification furnace to improve combustion efficiency.
[0002]
[Prior art]
Generally, a coal gasification combined power plant is provided with a coal gasification furnace that generates flammable gas by reacting pulverized coal with a gasifying agent, and gas purification equipment for the crude coal gas generated in the gasification furnace The fuel gas is generated by refining the gas, and the fuel gas is combusted by the gas turbine. The exhaust heat of the exhaust gas combusted by the gas turbine and steam are generated by the gasifier equipment, and the steam turbine is driven by the steam. It is configured to generate electricity, and the pyrolysis gas generated in the gasification furnace in recent years is cooled by a boiler, etc., and the fine powdered solid unburned coal (char) is captured by the cyclone and then gasified into the coal. It was returned to the furnace to improve thermal efficiency.
[0003]
This technique will be described with reference to FIG. 4. In the figure, reference numeral 1 denotes an air blown pressurized two-stage entrained bed gasification furnace composed of a combustor 1a and a reductor 1b. In the combustor 1a, pulverized coal (charcoal), char and char After injecting air and, if necessary, oxygen-enriched air for high-temperature combustion, further pulverized coal (coal) is further introduced into the upper reductor 1b and dry distillation gasification is performed using the high-temperature combustion of the combustor 1a. Let The gasified product gas such as CO and H ₂ is cooled by a cooler 12 such as a heat recovery boiler, and after char is collected and separated by a porous filter or cyclone, a gas heat exchanger 21, a COS converter 22, after removal of the ammonia in the ammonia removal device comprising a gas cooling tower 14 and the gas washing column 15 via a gas heat exchanger 23, it is sent to the H ₂ S absorption tower 16, to remove the H ₂ S.
In the H ₂ S absorption tower 16, sulfur compounds such as H ₂ S, COS and the like in the crude product gas are removed by the absorption liquid to an allowable concentration of the gas turbine 17 or less.
[0004]
On the other hand, the gas refined in the H ₂ S absorption tower 16 is heated in sequence in the steam heat exchanger 24, the gas heat exchanger 23 and the gas heat exchanger 21 and sent to the gas turbine 17 to generate power. The combustion exhaust gas from the gas turbine 17 is cooled by an unillustrated exhaust heat recovery boiler, and at the same time, the high-pressure steam heated by the steam heat exchanger 24 is recovered, and the obtained steam is an unillustrated steam. Power is generated by being sent to the turbine.
[0005]
The absorbent that has absorbed the sulfur compounds such as H ₂ S in H ₂ S absorption tower 16 is sent to an absorption regeneration tower 18, the H ₂ S which is absorbed by heating the absorption liquid regeneration heater 19 desorbed Played.
[0006]
However, the calorific value of the fuel gas generated in such a char recirculation-type coal gasifier has fluctuated due to fluctuations in the input amount of unburned coal (char) generated.
In general, the amount of char input is controlled in combination with weight control so that the hopper weight of the circulation system is kept constant or the calorific value is kept constant to some extent. It has been extremely difficult to prevent the amount of char input from fluctuating due to temporary clogging of the burner or fluctuation in the flow rate in the conveyance path from the hopper to the gasification furnace when jetting into the gasification furnace and burning.
The calorific value of the product gas fluctuates due to the fluctuation of the char, and as a result, the output of the gas turbine generator, that is, the plant load fluctuates, so that a stable power generation output cannot be obtained.
[0007]
Japanese Patent Laid-Open No. 2000-328074, for example, discloses a char recirculation system.
This technology is equipped with a coal gasification furnace that reacts pulverized coal with a gasifying agent to generate combustible gas, and char is generated when combustible gas (pyrolysis gas) is generated. Recycled into a coal gasifier. In such a coal gasification system, a part of the combustible gas after char recovery is taken out and heated by a heat exchanger. And the pulverized coal and char are supplied to a coal gasification furnace using the combustible gas after the heating as a carrier gas.
[0008]
However, in such a technique, the object of the present invention is to prevent condensation of moisture in the gas when the carrier gas is mixed with the pulverized fuel and to stably carry the pulverized fuel. It is not taken into account that the calorific value fluctuates due to fluctuations in char. In particular, since the combustible gas is used as the carrier gas for the char, the variation in the calorific value is further increased.
[0009]
[Problems to be solved by the invention]
In view of the problems of the prior art, the present invention provides a gas calorific value of combustible gas obtained from a coal gasification furnace, an output of a gas turbine, etc. in order to stabilize the gas calorific value and the output of a gas turbine. Instead of controlling the coal (pulverized coal) input to the coal gasifier based on the secondary fluctuations of the above, the amount of coal is increased by correcting from the amount of char input itself. Another object is to keep the heat ratio in the coal gasification furnace constant because the air ratio in the furnace is kept constant, and as a result, to stabilize the heat value of the gas and the output of the gas turbine and the like.
Another object of the present invention is to increase the amount of coal and keep the calorific value and output constant until char is generated at start-up and is accumulated in the hopper.
[0010]
[Means for Solving the Problems]
In order to solve such a problem, the present invention purifies rough flammable gas generated in a coal (pulverized coal) gasification furnace facility with a gas purification facility to generate a fuel gas, and the fuel gas is generated by a gas turbine. The char circulation type is configured to generate power by burning, and separate unburned coal (hereinafter referred to as char) from the crude gas through a solid-gas separator and return it to the gasifier through a conveyance path. In the coal gasification power plant system,
During the coal gasification furnace start, without circulating operation of the char, by increasing the coal input amount to operate, until the char to the supply device by a predetermined amount of stored, to maintain the increase in coal input amount, the A first step of starting the circulation control of the char that returns the char to the gasifier when a predetermined amount of char has accumulated in the char supply device ;
Wherein after the first step ends, the air while detecting the amount of return char or its variation in circulation control of the char, the flow rate of the oxidizing agent such as oxygen is constant, theory for combustibles obtained by summing the amount of coal and char weight The coal input amount is controlled so that the ratio of the combustion air amount and the input oxygen amount (in-furnace air ratio) is constant.
Thus, in order to keep the generated gas calorific value generated from the coal gasification furnace constant, the flow rate of oxidizers such as air and oxygen input to the gasification furnace is constant, and only the amount of coal input is limited. Ru is increased or decreased control.
Rather than controlling the amount of coal input to the coal gasifier based on secondary fluctuations such as the gas calorific value of the combustible gas obtained from the coal gasifier and the output of the gas turbine, etc. Since the amount of coal is increased by correcting from the amount of char input itself, the input control amount is accurately and reliably performed and there is no time delay.
[0011]
In particular, the present invention is essentially maintaining the calorific value of the coal gasification furnace constant from keeping the furnace air ratio constant, the product gas heating value as a result and it is possible to stabilize the output of the gas turbines, etc. I can do it.
[0012]
The specific device of the present invention is configured to return the char to the gasification furnace from the conveyance path via the char supply device that temporarily stores the char recovered by the solid-gas separator, and the first after step, the supply the transport path char flow rate variation and flowing obtained by calculating from the weight change of the apparatus, the transport path char flow rate change and the conveyance path obtained by calculating from the char density and flow rate of the The amount of coal to be input may be controlled based on the char flow rate change obtained by calculating from the differential pressure.
[0013]
The present onset Ming, the coal gasifier startup in a first step, without performing the circulation operation of the char, by increasing the coal input amount to operate, until the char to the supply device by a predetermined amount accumulates The increase in the input amount of coal is maintained, and the circulation control of char is started when a predetermined amount is accumulated.
[0014]
In the conventional technology, since no char is generated even when a constant amount of coal is input at the time of start-up, the amount of heat generated in the coal gasification furnace decreases until char accumulates in the supply device (hopper). As the gas calorific value and the output of the gas turbine, etc. become unstable at startup, according to the present invention, the amount of coal is increased until the amount of char circulation is stabilized, and as a result, the calorific value of the combustible gas generated from the furnace and The output can be kept constant.
Such an invention provides a transfer path for returning the char to the gasification furnace via a char supply device that temporarily stores the char recovered by the solid-gas separator, and in the first step, What is necessary is just to comprise so that a char amount may be detected and a predetermined amount of char accumulation may be judged.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings. However, unless otherwise specified, the dimensions, shapes, relative arrangements, and the like of the components described in this embodiment are merely illustrative examples and not intended to limit the scope of the present invention.
FIG. 1 is a block diagram showing a main part of a char circulation path according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes an air-blown pressurized two-stage entrained bed gasifier comprising a combustor 1a and a reductor 1b. After pulverized coal (coal), char, air, and oxygen-enriched air as necessary are combusted at a high temperature, the pulverized coal (coal) is further introduced into the upper reductor 1b. Dry distillation gasification using high temperature combustion. 40 and 41 are blowers. After the gasified product gas such as CO and H ₂ is cooled by a cooler 12 such as a heat recovery boiler, the char is recovered and separated by a char recovery device 13 such as a porous filter or a cyclone, and then the wake flow described above. The purified gas is sent to the gas turbine and sent to the gas turbine for predetermined power generation. The combustion exhaust gas from the gas turbine is cooled by a heat recovery steam generator (not shown) and at the same time high-pressure steam is generated. It is collected and sent to a steam turbine for power generation.
[0016]
On the other hand, the char recovered and separated by the char recovery device 13 is returned to the gasification furnace 1 by using an inert gas or the like by the transfer pipe 8 and a powder transfer machine 7 such as a venturi feeder provided in the transfer pipe 8.
Such a configuration is known.
[0017]
In the present invention, as shown in FIG. 1A, a load cell 20 is provided in the hopper 10 as the char supply device, and a change in weight (weight / time) of the char stored in the hopper 10 is detected. At the same time, a differential pressure gauge 5 is provided in the middle of the transport pipe 8, and the char flow rate is calculated by measuring the differential pressure of the char flowing through the transport pipe 8.
According to this embodiment, as shown in FIG. 2A, the char fluctuation detection circuit 3 obtains the differential pressure of the differential pressure gauge 5 from the change in the weight of the char that is taken in from the load cell 20 and is primarily stored in the hopper 10. The char weight returned to the coal gasification furnace at every sampling interval is determined by correcting the flow rate of the char gas mixture flow flowing in the transport pipe 8.
Then, in the coal command circuit 4, the char return weight is subtracted from the reference char set value by the subtractor 32 to obtain a fluctuation value, and an increase / decrease amount of the coal input corresponding to the equivalent energy corresponding to the fluctuation weight is obtained by the subtractor 33. By subtracting from the reference input amount, increase / decrease control of the input amount of coal is performed. In this case, in order to keep the calorific value in the coal gasification furnace constant, the flow rate of oxidizers such as air and oxygen charged into the gasification furnace 1 is constant, and only the input coal quantity is controlled to increase or decrease. The As a result, as shown in FIG. 3 (A), since the increase / decrease control of the coal amount commensurate with the equivalent energy of the variation of the char input amount can be performed, the input control amount is accurately and reliably performed and there is no time delay.
[0018]
The char return amount or its fluctuation amount is detected, and the ratio of the theoretical combustion air amount and the input oxygen amount (in-furnace air ratio) with respect to the combustible component obtained by adding the coal amount and the char amount is constant. It is preferable to control the input amount. For this reason, it may be necessary to control the air amount. However, since the control becomes complicated, the increase / decrease control only for the coal amount is performed.
As a result, the furnace air ratio is kept constant, so that the calorific value in the coal gasification furnace is essentially kept constant, and as a result, the gas calorific value and the output of the gas turbine and the like can be stabilized.
[0019]
Now, when the coal gasification furnace 1 is started up, since a conventional amount of coal is conventionally charged, char is not stored in the hopper 10, so as shown in (S1) of FIG. Until the char is accumulated in the supply device (hopper 10), the calorific value in the coal gasification furnace decreases, and as a result, the gas calorific value and the output of the gas turbine and the like become unstable at startup.
Therefore, the load cell 20 provided in the hopper 10 as the char supply device detects the weight of the char stored in the hopper 10 and performs the circulation operation of the char at the start of the coal gasifier in the start-up circuit. It is better to operate with an increased amount of coal input and maintain an increase in the amount of coal input until the supply device accumulates a predetermined amount of char. .
[0020]
That is, as shown in FIG. 2 (B) and FIG. 3 (B) (2), after the start of the gasification furnace 1 (S1), the input amount of coal is increased by 40% with respect to the steady input amount (100%) 1. The gasification furnace 1 is operated in the state (S2), during which the char weight in the hopper 10 is measured (S3), and the char is charged at the stage (S4) when the char weight in the hopper reaches the reference value. Start (S5), and control the coal input amount so that the ratio of the theoretical combustion air amount and the input oxygen amount (in-furnace air ratio) with respect to the combustible component obtained by adding the coal amount and the char amount becomes constant. Then, after shifting to a steady state in which coal is 100% and char is 40%, the control of FIG. 3A is continued (S6).
According to the embodiment, the amount of coal is increased until the amount of char circulation is stabilized, and as a result, the calorific value and output of the combustible gas generated from the furnace can be kept constant.
[0021]
【The invention's effect】
As described above, according to the present invention, in order to stabilize the gas calorific value and the output of the gas turbine, etc., the gas calorific value of the combustible gas obtained from the coal gasification furnace, the output of the gas turbine, etc. Rather than controlling the coal (pulverized coal) input to the coal gasifier based on the next change, the amount of coal can be increased by correcting the amount of char input itself. In particular, in order to keep the generated gas calorific value generated from the coal gasification furnace constant, the flow rate of oxidizers such as air and oxygen input to the gasification furnace is kept constant, and only the input coal quantity is controlled to increase or decrease. Thus, since the furnace air ratio is kept constant, the heat generation amount in the coal gasification furnace is essentially kept constant, and as a result, the gas heat generation amount and the output of the gas turbine and the like can be stabilized.
Further, according to the present invention, char is generated at the time of start-up, and the amount of coal can be increased to keep the heat generation amount and output constant until the char is accumulated in the hopper.
[Brief description of the drawings]
1A and 1B are main part configuration diagrams showing a char circulation path according to an embodiment of the present invention, in which FIG. 1A is a first embodiment and FIG. 1B is a second embodiment;
It is.
FIG. 2A is a block diagram showing the operation of FIG. 1, showing an operating state. (B) is a flowchart which shows the flow at the time of starting of FIG.
3A is a graph showing the input amounts of coal and char in the operating state in the embodiment of FIG. 1, and FIG. 3B is the graph (1) showing the input amounts of coal and char at the start-up of the prior art. Graph (2) of (B) is a graph showing the input amounts of coal and char of the example.
FIG. 4 is an overall view of a combined coal gasification combined power generation system corresponding to FIG. 1 according to a conventional technique.
[Explanation of symbols]
1 Gasification furnace 1a Combustor 1b Reductor 3 Char fluctuation detection circuit 4 Coal input command circuit 5 Differential pressure gauge 10 Hopper 12 Char recovery device 20 Load cell 50 Flow meter

Claims

The coarse flammable gas generated in the coal (pulverized coal) gasification furnace equipment is refined in the gas purification equipment to generate fuel gas, and the fuel gas is burned in the gas turbine to generate power, and the crude gas In a char circulation type coal gasification power plant system configured to separate unburned coal (hereinafter referred to as char) through a solid-gas separator and return it to a gasification furnace through a conveyance path,
During the coal gasification furnace start, without circulating operation of the char, by increasing the coal input amount to operate, until the char to the supply device by a predetermined amount of stored, to maintain the increase in coal input amount, the A first step of starting the circulation control of the char that returns the char to the gasifier when a predetermined amount of char has accumulated in the char supply device ;
Wherein after the first step ends, the air while detecting the amount of return char or its variation in circulation control of the char, the flow rate of the oxidizing agent such as oxygen is constant, theory for combustibles obtained by summing the amount of coal and char weight A char circulation type coal gasification power plant system that controls the amount of coal input so that the ratio of the combustion air amount and the input oxygen amount (in-furnace air ratio) is constant.

It is configured to return the char to the gasification furnace from the transfer path via a char supply device that temporarily stores the char recovered by the solid-gas separator, and after the first step, the weight change of the supply device The char flow rate obtained by calculating from the char flow rate change flowing through the transport path, the char flow rate change calculated from the char density and flow velocity of the transport path, and the char flow rate obtained by calculating from the differential pressure of the transport path The char circulation type coal gasification power plant system according to claim 1, wherein the amount of coal to be charged is controlled based on a change in flow rate.

The solid-gas the collected char in separator via the char supply device for storing temporarily together when providing a conveying path for returning the char to the gasifying furnace, and detects the char weight of the char supply device of a predetermined amount char The char circulation type coal gasification power plant system according to claim 1, wherein accumulation is judged.