JP2020045504A - Pulverized coal injection method - Google Patents
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本発明は、高炉のＰＣＩ（Pulverized Coal Injection:微粉炭吹き込み）において、微粉炭供給配管の詰まりを解消できる微粉炭吹き込み方法に関するものであり、特に微粉炭の高炉への供給を継続した状態で微粉炭供給配管の詰まりを解消できる微粉炭吹き込み方法に関するものである。 The present invention relates to a pulverized coal injection method capable of eliminating clogging of a pulverized coal supply pipe in PCI (Pulverized Coal Injection) of a blast furnace, and particularly to a pulverized coal injection method in which pulverized coal is continuously supplied to a blast furnace. The present invention relates to a method of injecting pulverized coal that can eliminate clogging of a coal supply pipe.
高炉の主たる還元材はコークスであるが、羽口から補助還元材料として微粉炭（Pulverized Coal：ＰＣ）を吹込むことにより高生産性、高効率化が促進されてきた。一般的に、微粉炭吹き込み（ＰＣＩ）装置は、石炭を所定の粒度に粉砕した後、粉砕した微粉炭を搬送ガスに乗せて主配管を通じて供給し、分配器により羽口数に応じて分岐させた支管（分岐支管）を通して高炉内へ吹き込む。羽口の数は、高炉のサイズや形状によって異なるが、大型化された高炉では約３０〜４０におよぶこともある。その約３０〜４０におよぶ羽口は、炉内の還元反応バランスを考慮して、高炉本体の下部で、円周方向に均等に配置されることが一般的である。微粉炭（ＰＣ）の供給分岐支管の数は、羽口の数が数十に応じた数であり、羽口が数十であれば、ＰＣ供給分岐支管の数も数十におよぶ。 Although the main reducing agent of the blast furnace is coke, high productivity and high efficiency have been promoted by injecting pulverized coal (PC) as an auxiliary reducing material from the tuyere. In general, a pulverized coal injection (PCI) device pulverizes coal to a predetermined particle size, and then supplies the pulverized pulverized coal to a carrier gas through a main pipe, and branches the pulverized coal according to the number of tuyeres by a distributor. It is blown into the blast furnace through a branch pipe (branch branch pipe). The number of tuyeres varies depending on the size and shape of the blast furnace, but may be as large as about 30 to 40 in a larger blast furnace. Generally, the tuyeres of about 30 to 40 are arranged evenly in the circumferential direction at the lower part of the blast furnace main body in consideration of the reduction reaction balance in the furnace. The number of supply branch branches of pulverized coal (PC) is a number corresponding to several tens of tuyeres, and if the number of tuyeres is several tens, the number of PC supply branch branches is also several tens.
当然のことながら、高炉内では安定的にバランスのとれた還元反応条件となるように、微粉炭（ＰＣ）が安定的に継続して高炉に吹き込まれることが望まれる。しかしながら、羽口の数が数十におよび、またそれに連なるＰＣ供給分岐支管の数も数十におよぶため、微粉炭（ＰＣ）吹き込み状況は分岐支管ごとに差異が生じていることがあり、その結果として高炉内の還元反応条件にバラツキを生じることがあり得る。また、実際の操業では、微粉炭（ＰＣ）やあるいは微粉炭内に混在している木片、ウエス、ビニール、糸くず等の異物が、微粉炭吹き込み装置の配管やノズル等で詰まることがしばしばあり、これが配管ごとの吹き込み状況の差異を生む一因となっている。このような詰まりは、高炉の安定操業に大きな悪影響を及ぼすため、詰まりが生じた系統の吹き込みラインからの吹き込みを停止し、逆洗パージガスや順洗パージガス等を詰まり部に吹き込んで、詰まりを解消することが行われてきた。 Naturally, it is desired that pulverized coal (PC) be continuously and stably blown into the blast furnace so that the reduction reaction conditions are stably balanced in the blast furnace. However, since the number of tuyeres is several tens, and the number of PC supply branch branches connected to it is also several tens, the pulverized coal (PC) injection situation may differ for each branch branch. As a result, the reduction reaction conditions in the blast furnace may vary. In the actual operation, foreign substances such as pulverized coal (PC) or wood chips, waste, vinyl, lint and the like mixed in the pulverized coal are often clogged by the pipes or nozzles of the pulverized coal blowing device. This is one of the causes of the difference in the blowing condition for each pipe. Since such clogging has a significant adverse effect on the stable operation of the blast furnace, stop the blowing from the blowing line of the system where the clogging occurred, and blow backwash purge gas or forward cleaning purge gas, etc., into the clogged part to eliminate the clogging. That has been done.
特許文献１は、詰まり解消のための逆洗ラインおよび詰まりの発生を検出する装置を、あらかじめ微粉炭吹き込み配管に設けておくことを提案している。吹込管内での詰まりの発生が検出されると、直ちに逆洗ラインで詰まりを解消するとしている。具体的には、微粉体自体はかなりの高温状態で搬送されるため、微粉炭が搬送される分岐配管の温度に着目した検出手段や紛体流量計により、詰まりを検出するとしている。そして、詰まり検出手段によって分岐支管の詰まりが検出されたならば、当該詰まりの生じている分岐支管の供給入側弁（分配器出口弁）および供給出側弁（高炉入口弁）を閉弁させたうえで、詰まり解消のための逆洗用ガス吹込管よりＮ2 ガスを詰まりの生じている分岐支管に供給して、分岐支管に詰まった微粉炭を除去している。図１および図２は、それぞれ、特許文献１の通常吹き込み状態と、詰まりが発生して逆洗を行っている状態を、模式的に示したものである。図中の黒色で表示されたバルブは、閉状態であることを意味する。 Patent Document 1 proposes that a backwash line for eliminating clogging and a device for detecting occurrence of clogging be provided in advance in a pulverized coal blowing pipe. When the occurrence of clogging in the blowpipe is detected, the clogging is immediately eliminated in the backwash line. Specifically, since the fine powder itself is transported in a considerably high temperature state, the clogging is detected by a detection means or a powder flow meter that focuses on the temperature of the branch pipe through which the pulverized coal is transported. When the clogging of the branch branch is detected by the blockage detecting means, the supply inlet valve (distributor outlet valve) and the supply outlet valve (blast furnace inlet valve) of the clogged branch branch are closed. in Ue is supplied to branch branch pipes occurring clogging the N 2 gas from the backwash gas blowing tubes for plugging overcome, and removing the pulverized coal jammed branch branch pipe. FIGS. 1 and 2 schematically show a normal blowing state and a state in which clogging occurs and backwashing is performed, respectively, in Patent Document 1. A valve displayed in black in the drawing means that the valve is in a closed state.
従来、特許文献１のように、高炉へのＰＣ分岐支管で詰まりが生じると、当該詰まりの生じた分岐支管でのＰＣ供給を停止したうえで、詰まりを解消するためパージ操作を行うことが一般的であった。この場合、詰まりが解消するまでは、当該分岐支管ラインからは、高炉内へＰＣおよび搬送用ガス等の供給ができない。これは、高炉内の還元反応バランスに少なからず影響を与え得る。高炉において、羽口の数、およびＰＣ供給ラインは、複数あり、数十におよぶこともあるが、それらが継続的に安定してＰＣおよび搬送用ガスを高炉内へ供給することにより、高炉内の還元反応バランスを保った運転が可能である。ところが、ＰＣ供給ラインのいずれか一つにおいて通常どおりにＰＣ等の供給がされていない状態になると、その羽口からはＰＣおよび搬送用ガス等が供給されず、その羽口において大幅な熱量変動を生じ、ひいては炉内の還元反応バランスが変動し、高炉から排出される銑鉄の製品品質に影響がおよぶことがあり得る。 Conventionally, when a PC branch branch to a blast furnace is clogged as in Patent Literature 1, it is common to stop the supply of PC to the clogged branch branch and then perform a purge operation to eliminate the blockage. It was a target. In this case, PC and carrier gas cannot be supplied into the blast furnace from the branch branch line until the blockage is eliminated. This can have a considerable effect on the reduction reaction balance in the blast furnace. In a blast furnace, the number of tuyeres and the number of PC supply lines are plural and sometimes dozens, but they are continuously and stably supplied to the blast furnace by supplying PC and carrier gas to the blast furnace. It is possible to operate while maintaining the reduction reaction balance. However, when the PC or the like is not supplied as usual in one of the PC supply lines, the tuyere does not supply the PC and the carrier gas, and a large heat quantity variation occurs at the tuyere. And the balance of the reduction reaction in the furnace may fluctuate, which may affect the product quality of pig iron discharged from the blast furnace.
上記の状況に鑑みて、本願発明は、高炉での微粉炭吹き込みにおいて、微粉炭の高炉への供給を継続した状態で微粉炭供給配管の詰まりを解消し、高炉において安定的かつ継続的にバランスのとれた還元反応条件を維持できる方法を提供することを目的とする。 In view of the above situation, the present invention eliminates clogging of pulverized coal supply pipes while pulverized coal is continuously supplied to the blast furnace during pulverized coal injection in the blast furnace, and stably and continuously balances in the blast furnace. It is an object of the present invention to provide a method capable of maintaining good reduction reaction conditions.
本発明により以下の態様が提供される。 The following aspects are provided by the present invention.
［１］気流輸送される微粉炭が分配器によって支管に分岐され、羽口を通じて高炉内へ吹き込まれ、ここで前記支管のそれぞれに支管流量調整弁および支管流量計が設置されている、微粉炭吹き込み方法において、
前記支管流量計で前記微粉炭の吹き込み量低下及び／または詰まりが確認された場合に、前記支管流量調整弁の開度を全開とすることを特徴とする、微粉炭吹き込み方法。
［２］平常運転時において、前記支管流量調整弁の開度を、前記支管流量調整弁での圧力損失が予め規定された範囲内になるように、設定し、
前記支管から前記羽口への微粉炭吹き込み量を、前記支管流量計を用いて、監視し、
前記微粉炭吹き込み量が、平常運転時の目標微粉炭吹き込み量と等しくなるように、前記支管流量調整弁の弁開度を調整することを特徴とする、［１］に記載の微粉炭吹き込み方法。
［３］さらに、前記微粉炭の吹き込み量低下及び／または詰まりが解消された後、前記支管流量調整弁の開度を、前記支管流量調整弁での圧力損失が予め規定された範囲内になるように、設定することを含む、［１］または［２］に記載の微粉炭吹き込み方法。
［４］前記支管での前記微粉炭の吹き込み量低下及び／または詰まりが、前記微粉炭吹き込み量が予め規定された判定基準を下回ったことにより、確認される、［１］から［３］のいずれか１つに記載の微粉炭吹き込み方法。
[1] Pulverized coal to be pneumatically transported is branched into branch pipes by a distributor and blown into a blast furnace through tuyeres, where a branch pipe flow control valve and a branch pipe flow meter are installed in each of the branch pipes. In the blowing method,
The pulverized coal blowing method, wherein when the pulverized coal blowing amount is confirmed to be reduced and / or clogged by the branch pipe flow meter, the opening of the branch pipe flow control valve is fully opened.
[2] During normal operation, the opening of the branch pipe flow control valve is set such that the pressure loss at the branch pipe flow control valve falls within a predetermined range,
The amount of pulverized coal blown from the branch pipe to the tuyere is monitored using the branch pipe flow meter,
The pulverized coal injection method according to [1], wherein the pulverized coal injection amount is adjusted so that the pulverized coal injection amount is equal to a target pulverized coal injection amount during normal operation. .
[3] Further, after the pulverized coal blowing amount is reduced and / or clogged, the opening degree of the branch pipe flow control valve is adjusted so that the pressure loss at the branch pipe flow control valve falls within a predetermined range. The pulverized coal blowing method according to [1] or [2], including setting as described above.
[4] The reduction of the pulverized coal blowing amount and / or clogging in the branch pipe is confirmed by the pulverized coal blowing amount falling below a predetermined criterion, [1] to [3]. The pulverized coal blowing method according to any one of the above.
本願発明によれば、高炉での微粉炭吹き込みにおいて、微粉炭の高炉への供給を継続した状態で微粉炭供給配管の吹き込み量低下及び／または詰まりを解消し、高炉において安定的かつ継続的にバランスのとれた還元反応条件を維持できる。 ADVANTAGE OF THE INVENTION According to this invention, in the pulverized coal injection in a blast furnace, while the supply of the pulverized coal to the blast furnace is continued, a reduction in the blowing amount and / or clogging of the pulverized coal supply pipe is eliminated, and the pulverized coal is stably and continuously supplied to the blast furnace. Balanced reduction reaction conditions can be maintained.
本発明の実施態様について説明する。
一般的な微粉炭吹き込み（ＰＣＩ）装置では、石炭を所定の粒度に粉砕した後、粉砕した微粉炭を搬送ガスに乗せて主配管に吹き込み、分配器により羽口数に応じて分岐させた支管（分岐支管）およびそれに連なる羽口を通して高炉内へ吹き込む。本発明による、微粉炭吹き込み（ＰＣＩ）装置は、支管（分岐支管）のそれぞれに支管流量計および支管流量調整弁が設置されている。
支管流量計により、支管から羽口への微粉炭吹き込み量を測定することができ、運転中にその吹き込み量が適切な範囲に維持されているかどうか、適切な範囲から逸脱していないかを監視することができる。
支管流量調整弁は、その弁開度を調整することができ、それにより支管での微粉炭吹き込み量を調整することが可能である。
なお、平常運転時に吹込み量が安定している場合は、支管での微粉炭吹き込み量を調整する必要はなく、支管流量調整弁の開度を一定として操業することができる。
An embodiment of the present invention will be described.
In a general pulverized coal injection (PCI) apparatus, after pulverizing coal to a predetermined particle size, the pulverized pulverized coal is loaded on a carrier gas and blown into a main pipe, and a branch pipe is branched by a distributor according to the number of tuyeres. (Branch branch pipe) and the tuyere connected thereto are blown into the blast furnace. In the pulverized coal injection (PCI) device according to the present invention, a branch pipe flow meter and a branch pipe flow control valve are installed in each of the branch pipes (branch branch pipes).
The branch pipe flow meter can measure the amount of pulverized coal blown from the branch pipe to the tuyere, and monitors whether the blown amount is maintained within the appropriate range during operation and whether it has deviated from the appropriate range. can do.
The branch pipe flow control valve is capable of adjusting the valve opening degree, thereby adjusting the pulverized coal blowing amount in the branch pipe.
When the blowing amount is stable during normal operation, it is not necessary to adjust the pulverized coal blowing amount in the branch pipe, and the operation can be performed with the opening degree of the branch pipe flow control valve being constant.
概して、粒度調整された微粉炭のみを吹き込む場合、支管内での吹き込み量の低下や詰まりは生じない。しかしながら、実際の微粉炭吹き込みでは、微粉炭やあるいは微粉炭内に混在している木片、ウエス、ビニール、糸くず等の異物が、支管（分岐支管）で詰まることがしばしばある。特定の理論に拘束されることを望むものではないが、詰まりが成長する機構として、微小な異物が支管内に堆積し、それを起点にさらに微粉炭やその他の異物の堆積が続き、堆積が大きくなり、支管内の流量を低下させて、結果として詰まりが生じることが考えられる。 In general, when only the pulverized coal whose particle size has been adjusted is blown, the amount of blown air in the branch pipe and clogging do not occur. However, when pulverized coal is actually blown, foreign matter such as wood chips, waste, vinyl, and lint mixed in the pulverized coal or pulverized coal is often clogged in the branch pipe (branch branch pipe). Although not wishing to be bound by any particular theory, the mechanism by which the clogs grow is that small foreign matter accumulates in the branch pipe, followed by pulverized coal and other foreign matter accumulation, starting from that point. It is conceivable that the air flow becomes large and reduces the flow rate in the branch pipe, resulting in clogging.
本発明者は、鋭意検討の結果、支管内で生じた微粉炭の吹き込み量低下及び／または詰まりを解消するために、以下の着想を得た。すなわち、支管内で微粉炭の吹き込み量低下及び／または詰まりが生じた際に、流量調整弁の開度を全開にする。これにより、流量調整弁での圧力損失が低下し、微粉体またはそれを吹き込む気流が流れやすくなり、流量（吹き込み量）が増加し、ひいては支管内の詰まりを解消するように作用させることができる。全開にする前の流量調整弁の開度範囲は特に限定されるものではない。ただし、開度が小さすぎると平常運転時の圧力損失が大きくなりすぎることがある。圧力損失が大きくなると、タンク圧力が過度に上昇することがあり、また同一の弁操作でも制御対象（吹き込み量）の変化量が大きくなって微調整が困難なことがある。そのため、弁開度は３０％以上、好ましくは４０％以上としてもよい。一方、開度が大きすぎると、流量低下や詰まり発生時に全開にした場合の圧力ポテンシャルが十分でなく、流量低下や詰まりが解消しにくいことがあるので、弁開度を６０％以下、好ましくは５０％以下としてもよい。 As a result of intensive studies, the present inventor has obtained the following idea in order to eliminate a decrease in the amount of pulverized coal blown and / or clogging generated in the branch pipe. That is, when the amount of pulverized coal to be blown is reduced and / or clogged in the branch pipe, the opening of the flow control valve is fully opened. As a result, the pressure loss at the flow control valve is reduced, and the fine powder or the airflow that blows it becomes easier to flow, the flow rate (blowing amount) increases, and the clogging of the branch pipe can be prevented. . The opening range of the flow control valve before it is fully opened is not particularly limited. However, if the opening is too small, the pressure loss during normal operation may be too large. When the pressure loss increases, the tank pressure may increase excessively, and even with the same valve operation, the amount of change in the control target (blowing amount) may increase, making fine adjustment difficult. Therefore, the valve opening may be 30% or more, preferably 40% or more. On the other hand, if the opening degree is too large, the pressure potential when fully opened when the flow rate decreases or clogging occurs is not sufficient, and the flow rate reduction or clogging may be difficult to be eliminated. Therefore, the valve opening degree is set to 60% or less, preferably It may be 50% or less.
さらに、高炉の平常運転時において、微粉炭の吹き込み量が、平常運転時の目標微粉炭吹き込み量と等しい量になっているかを支管流量計で監視し、その範囲を逸脱しそうな兆候があれば、支管流量調整弁の開度を調整してもよい。別の言い方をすると、微粉炭吹き込み量の目標値と実績値の差異に応じて弁開度を調整してもよい。これにより、微粉炭の吹き込み量が、平常運転時の目標微粉炭吹き込み量と等しくなるように、制御される。その結果、平常運転時に、微粉炭供給量は一定であり、高炉内では安定した還元反応条件が維持される。 Furthermore, during normal operation of the blast furnace, the pulverized coal injection amount is monitored with a branch pipe flow meter to determine whether the amount of pulverized coal injected is equal to the target pulverized coal injection amount during normal operation. Alternatively, the opening of the branch pipe flow control valve may be adjusted. Stated another way, the valve opening may be adjusted according to the difference between the target value and the actual value of the pulverized coal injection amount. Thus, the pulverized coal blowing amount is controlled so as to be equal to the target pulverized coal blowing amount during normal operation. As a result, during normal operation, the supply amount of pulverized coal is constant, and stable reduction reaction conditions are maintained in the blast furnace.
なお、前述のとおり、平常運転時に吹込み量が安定している場合は、このような制御を行わず、支管流量調整弁の開度を一定として操業してもよい。平常運転時の吹き込み量が安定しているかどうかは、操業条件に応じて適宜判断されるものである。微粉炭の吹き込み量が、平常運転時の目標微粉炭吹き込み量を基準として、所定時間内に±３０％以上、好ましくは±２０％以上、より好ましくは±１０％以上の変動をする場合に、吹き込み量が安定していないと判断して、支管流量調整弁の開度を調整する制御を行ってもよい。吹き込み量の変動を測定する所定時間とは、運転状況に応じて適宜設定されるものであり、特に限定されるものではなく、数分間〜数十分（例えば１分以上３０分以下）の範囲から選択してもよい。 As described above, when the blowing amount is stable during normal operation, such control may not be performed, and the operation may be performed with the opening of the branch pipe flow control valve being constant. Whether or not the blowing amount during normal operation is stable is appropriately determined according to operating conditions. When the injection amount of pulverized coal fluctuates by ± 30% or more, preferably ± 20% or more, more preferably ± 10% or more within a predetermined time with respect to the target pulverized coal injection amount during normal operation, It may be determined that the blowing amount is not stable, and control may be performed to adjust the opening of the branch pipe flow control valve. The predetermined time for measuring the fluctuation of the blowing amount is appropriately set according to the driving situation, and is not particularly limited, but is in a range of several minutes to several tens of minutes (for example, 1 minute to 30 minutes). You may choose from.
平常運転時において、支管に設置された流量調整弁での圧力損失が予め規定した範囲内になるように、流量調整弁の開度を設定しておくことができる。（この開度設定は、平常運転時に、支管流量調整弁の開度を一定とする場合、支管流量調整弁の開度を調整する場合のいずれでも適用可能である。）開度設定に応じて、流量調整弁で圧力損失が生じ、その圧力損失が大きいほど、流量調整弁以降の支管では微粉体またはそれを吹き込むための気流は流れにくくなる。逆に、流量調整弁の開度を開けていくと、圧力損失は小さくなり、微粉体または気流は流れやすくなり、流量（吹き込み量）が増加する。そのため、支管内で微粉炭の吹き込み量低下及び／または詰まりが生じた際に、流量調整弁の開度を全開にすることにより、圧力損失が低下し、微粉体またはそれを吹き込む気流が流れやすくなり、流量（吹き込み量）が増加し、ひいては支管内の詰まりを解消するように作用させることができる。 During normal operation, the opening of the flow control valve can be set so that the pressure loss at the flow control valve installed in the branch pipe falls within a predetermined range. (This opening setting can be applied to the case where the opening of the branch pipe flow control valve is constant during normal operation or the case where the opening of the branch pipe flow adjusting valve is adjusted.) In accordance with the opening setting In addition, pressure loss occurs in the flow control valve, and the larger the pressure loss, the harder the fine powder or the air flow for blowing the fine powder flows in the branch pipe after the flow control valve. Conversely, as the opening of the flow control valve is increased, the pressure loss decreases, the fine powder or the air flow becomes easier to flow, and the flow rate (blowing amount) increases. Therefore, when the amount of pulverized coal to be blown is reduced and / or clogged in the branch pipe, by fully opening the flow control valve, the pressure loss is reduced, and the fine powder or the airflow blowing it is easy to flow. As a result, the flow rate (blowing amount) is increased, and thus, it is possible to act to eliminate clogging in the branch pipe.
予め規定しておく圧力損失の範囲は、吹き込まれる微粉炭やガスの性状や、支管の形状等に起因する詰まりの発生しやすさ、ならびに流量調整弁の弁開度特性等を考慮して、適宜設定することができる。予め規定された圧力損失が得られれば、流量調整弁の開度範囲は特に限定されるものではない。ただし、開度が小さすぎると平常運転時の微粉炭吹き込み量の変動に追随するための開度調整裕度が狭く、制御が困難なことがあるので、弁開度を３０％以上、好ましくは４０％以上としてもよい。一方、開度が大きすぎると、流量低下や詰まり発生時に全開にした場合の圧力ポテンシャルが十分でなく、流量低下や詰まりが解消しにくいことがあるので、弁開度を６０％以下、好ましくは５０％以下としてもよい。 The range of the pressure loss to be specified in advance is determined in consideration of the properties of the pulverized coal or gas to be blown and the likelihood of clogging due to the shape of the branch pipe, and the valve opening characteristics of the flow control valve. It can be set appropriately. As long as a predetermined pressure loss can be obtained, the opening range of the flow control valve is not particularly limited. However, if the opening is too small, the opening adjustment allowance for following the fluctuation of the pulverized coal blowing amount during normal operation is narrow and control may be difficult. Therefore, the valve opening is set to 30% or more, preferably It may be 40% or more. On the other hand, if the opening degree is too large, the pressure potential when fully opened when the flow rate decreases or clogging occurs is not sufficient, and the flow rate reduction or clogging may be difficult to be eliminated. Therefore, the valve opening degree is set to 60% or less, preferably It may be 50% or less.
弁開度、圧力損失および流量との間には、流体特性や配管構成等の影響を受けるものの、一定の相関関係が存在すると考えられる。すなわち、一般的には、弁開度が大きいほど、圧力損失は小さく、流量は大きくなる傾向が認められる。したがって、詰まりを解消するために必要とされる流量の増加分を想定しておき、そのような流量増加が得られるような圧力損失量や弁開度を設定することができる。逆に、支管（分岐支管）に設置された流量調整弁の弁特性（弁開度）から、実現可能な流量の増減を確認しておき、詰まりを解消するための必要とされる流量の増加分が得られるように、弁開度を設定してもよい。平常運転時の流量は、高炉の運転条件に基づいて任意に設定されるものであり、通常のキャリアガス流量として１００Ｎｍ３／ｈ前後（±３０％）を採用してもよい。これに対して、流量低下や詰まりを解消するための流量は、平常運転時の流量より多いことが必要であり、多いほど好ましいが、一方で流量低下や詰まりを解消するために必要な流量以上とすることは不要である。そのため、詰まりを解消するための流量は、平常運転時の流量の１．２倍以上、好ましくは１．５倍以上であってもよく、２．０倍以下、好ましくは１．７倍以下であってもよい。
また、流量調整弁での圧力損失を指標とすることができ、全開時に流量を増して、流量低下や詰まりを解消させる観点からはできるだけ圧力損失が大きい方が好ましいが、一方でそのような大きい圧力損失を得るには流量調整弁の耐圧性等を過剰に向上させたり、平常運転時の流量調整範囲が過剰に制限されたりする等、設備や運転上の制約が増す。例えば、吹込みタンク圧力の耐圧上限にかかってしまうため、最大０．２ＭＰａ程度しか増加させられない、あるいは、圧力損失を得るために過剰な流速が必要であり、それによって流量調整部の摩耗が進む等の問題がある。上記の観点から、適当平常運転時の流量に対して適切な圧力損失となるように設定することができ、０．０１〜０．２ＭＰａ程度の圧力損失となるように、弁開度を調整してもよい。
It is considered that there is a certain correlation between the valve opening degree, the pressure loss, and the flow rate, though it is affected by the fluid characteristics, the piping configuration, and the like. That is, generally, the larger the valve opening is, the smaller the pressure loss and the larger the flow rate is. Therefore, the amount of increase in the flow rate required to eliminate the clogging is assumed, and the pressure loss amount and the valve opening that can obtain such an increase in the flow rate can be set. Conversely, from the valve characteristics (valve opening) of the flow control valve installed in the branch pipe (branch branch pipe), it is confirmed whether the achievable increase or decrease in the flow rate is increased, and the increase in the flow rate required to eliminate the clogging is confirmed. The valve opening may be set so that the minute is obtained. The flow rate during normal operation is arbitrarily set based on the operating conditions of the blast furnace, and a normal carrier gas flow rate of around 100 Nm 3 / h (± 30%) may be employed. On the other hand, the flow rate for eliminating the flow rate decrease and clogging needs to be larger than the flow rate during normal operation, and the more it is preferable, the more the flow rate is necessary for eliminating the flow rate decrease and clogging. Is not necessary. Therefore, the flow rate for eliminating the clogging may be 1.2 times or more, preferably 1.5 times or more, 2.0 times or less, preferably 1.7 times or less of the flow rate during normal operation. There may be.
In addition, the pressure loss at the flow control valve can be used as an index, and from the viewpoint of increasing the flow rate at the time of full opening and eliminating the flow rate decrease and clogging, it is preferable that the pressure loss is as large as possible. In order to obtain a pressure loss, restrictions on equipment and operation are increased, such as excessively improving the pressure resistance of the flow control valve and excessively restricting the flow control range during normal operation. For example, since the upper limit of the withstand pressure of the blowing tank pressure is applied, only a maximum of about 0.2 MPa can be increased, or an excessive flow rate is required to obtain a pressure loss, thereby causing abrasion of the flow control section. There are problems such as progress. From the above point of view, it is possible to set the pressure loss to be appropriate for the flow rate during normal operation, and to adjust the valve opening so that the pressure loss is about 0.01 to 0.2 MPa. You may.
流量低下や詰まりを解消するために、流量調整弁の開度を全開にする場合、弁はできるだけ迅速に開度を大きくすることが好ましい。全開にする速度が速いほど、流量低下や詰まり解消のためのインパクトが大きくなるためである。流量調整弁の開度調整手法によって決まる弁開度調整速度の最大許容速度で全開にしてもよい。定量的に表現すれば、流量調整弁の開度を全開にするまでの時間が、３秒以内であることが好ましい。さらに好ましくは１秒以内であってもよい。なお、流量調整弁を全開にしてから、数十秒程度（例えば６０±１０秒）全開状態を維持して、パージガスが十分に通過するように、すなわち詰まりが十分に解消するようにしてもよい。 When the opening of the flow control valve is fully opened in order to eliminate the flow rate decrease and clogging, it is preferable to increase the opening of the valve as quickly as possible. This is because the higher the speed of full opening, the greater the impact of reducing the flow rate and eliminating clogging. The valve may be fully opened at the maximum allowable speed of the valve opening adjustment speed determined by the opening adjustment method of the flow control valve. Quantitatively, it is preferable that the time until the opening of the flow control valve is fully opened is within 3 seconds. More preferably, it may be within one second. After the flow regulating valve is fully opened, the fully opened state may be maintained for about several tens of seconds (for example, 60 ± 10 seconds) so that the purge gas sufficiently passes, that is, the clogging may be sufficiently eliminated. .
微粉炭を気流輸送するための流体は、高炉内へ搬送される流体であり、高炉内での還元反応条件や微粉炭の性状や輸送量に応じて調製される。微粉炭と輸送のための気流流体の割合（固気比[ｋｇ／ｋｇ]）が調整されてもよい。固気比が高すぎると、流量低下や詰まりが生じやすく、流量低下や詰まり解消のために流量調整弁の開度を全開にして、流量を増加させても、流量低下や詰まりが解消しにくい場合がある。流量低下や詰まりを生じにくくする観点からは、固気比は低い方が安定的な吹込み状況は得られるために好ましい。ただし、固気比が低すぎると、すなわち気流流体の割合が高くなると、配管の圧力損失増加や用役コスト悪化等の課題がある。そのため、固気比（ｋｇ／ｋｇ）は、３以上〜５０以下で操業してもよい。 The fluid for pneumatically transporting the pulverized coal is a fluid conveyed into the blast furnace, and is prepared in accordance with the reduction reaction conditions in the blast furnace, the properties of the pulverized coal, and the transport amount. The ratio of the pulverized coal and the airflow fluid for transportation (solid-gas ratio [kg / kg]) may be adjusted. If the solid-gas ratio is too high, the flow rate decreases and clogging is likely to occur, and even if the flow control valve is fully opened to reduce the flow rate and eliminate the clogging and the flow rate is increased, it is difficult to eliminate the flow rate decrease and clogging There are cases. From the viewpoint of reducing the flow rate and preventing clogging, it is preferable that the solid-gas ratio is low because a stable blowing state can be obtained. However, if the solid-gas ratio is too low, that is, if the ratio of the airflow fluid is high, there are problems such as an increase in pressure loss of pipes and deterioration of utility costs. Therefore, the operation may be performed at a solid-gas ratio (kg / kg) of 3 to 50.
上記に記載した方法により、微粉炭の吹き込みの供給を継続しながら、支管（分岐支管）での詰まりを解消することが可能である。従来は、流量低下や詰まりを解消するためのパージを行う際に、微粉炭の供給を停止するのが一般的であった。そのため、流量低下や詰まりの解消を行うと、高炉内での還元反応条件が平常運転時とは異なるものとなり、特に、複数ある支管（分岐支管）の一つから微粉炭の供給がなく、その他の支管では微粉炭が供給されているため、高炉内の還元反応バランスに大きく影響する場合がある。本発明により、そのような還元反応条件の変動が小さくなり、還元反応バランスを継続的に安定に保つことができ、これにより製品品質の維持、向上に極めて有用である。 By the method described above, it is possible to eliminate clogging in the branch pipe (branch branch pipe) while continuing to supply the pulverized coal. Conventionally, the supply of pulverized coal has generally been stopped when purging to reduce the flow rate or eliminate clogging. Therefore, if the flow rate is reduced or clogging is eliminated, the reduction reaction conditions in the blast furnace will be different from those during normal operation, and in particular, pulverized coal will not be supplied from one of the plurality of branch pipes (branch branch pipes). Since the pulverized coal is supplied to the branch pipe, the reduction reaction balance in the blast furnace may be greatly affected. According to the present invention, such fluctuations in the reduction reaction conditions are reduced, and the reduction reaction balance can be maintained continuously and stably, which is extremely useful for maintaining and improving product quality.
流量調整弁を全開にして、支管内での微粉炭の流量低下及び／または詰まりが解消された後は、流量調整弁の開度を、予め規定された圧力損失の範囲になるように設定してもよい。これにより、平常運転時の弁開度に戻すことになり、吹き込み量が安定している場合は流量調整弁を一定開度にすることができ、また、流量調整弁の開度を調整する制御を行う場合は微粉炭の吹き込み量が平常時の目標吹き込み量と等しくするための流量制御を再開できる。これらの結果、高炉内での安定した還元反応条件を継続的に維持することが可能である。 After the flow control valve is fully opened and the decrease in flow rate and / or clogging of the pulverized coal in the branch pipe is eliminated, the opening of the flow control valve is set so as to be within a predetermined pressure loss range. You may. As a result, the valve opening is returned to the normal operation valve opening. When the blowing amount is stable, the flow regulating valve can be kept at a constant opening, and the control for adjusting the opening of the flow regulating valve can be performed. Is performed, the flow control for making the amount of pulverized coal blown equal to the target amount of blown air in normal times can be restarted. As a result, stable reduction reaction conditions in the blast furnace can be continuously maintained.
支管内で微粉炭の流量低下及び／または詰まりが発生しているかどうかは、一般的に用いられる閉塞判断手法を用いてもよい。本発明では、支管に設置された支管流量計で流量（微粉炭吹き込み量）を監視しているため、監視している現在（または通常時）の流量を平常運転の基準（例えば１．０）として、流量低下の判定基準（例えば０．７）や詰まりの判定基準（例えば０．５）を設定しておき、監視している流量が前記の判定基準を下回った場合、支管内で流量低下及び／または詰まりが生じていると判断してもよい。判定基準は、微粉炭性状、配管構成、高炉還元反応条件等に応じて適宜設定してもよい。平常運転時は、微粉炭吹き込み量が目標値と等しくなるように調整されているため、流量が、平常運転時の目標流量を１．０として、それよりも数割程度（例えば、０．３〜０．５）以上、低下した場合に、流量低下や詰まりが生じていると判断してもよい。 Whether the flow rate of the pulverized coal is reduced and / or clogged in the branch pipe may be determined by a generally used blockage determination method. In the present invention, since the flow rate (pulverized coal blowing amount) is monitored by the branch pipe flow meter installed in the branch pipe, the current (or normal) flow rate being monitored is set to the standard for normal operation (for example, 1.0). As a reference, a criterion for determining a decrease in flow rate (for example, 0.7) or a criterion for determining clogging (for example, 0.5) is set, and if the monitored flow rate falls below the criterion, the flow rate decreases in the branch pipe. And / or it may be determined that clogging has occurred. The criterion may be appropriately set according to the properties of the pulverized coal, the piping configuration, the blast furnace reduction reaction conditions, and the like. During normal operation, since the pulverized coal injection amount is adjusted to be equal to the target value, the flow rate is set to 1.0 as the target flow rate during normal operation, and the flow rate is about several percent (for example, 0.3%). -0.5) If the flow rate is reduced, it may be determined that the flow rate is reduced or clogged.
本発明について、以下の実施例を通じて説明する。ただし、本発明の範囲は、実施例によって限定して解釈されるものではない。 The present invention will be described through the following examples. However, the scope of the present invention is not construed as being limited by the examples.
内容積５０００ｍ３ であって、その周囲に４０箇所の羽口を有する実規模の高炉を想定して、分配器（ディストリビューター）以降の、羽口までの配管（支管：分岐支管に相当）を用意し、当該配管には上流側から支管流量調整弁、三方弁、支管流量計が設置された。図３〜５は、本実施例および参考例での装置構成および気体の流れを模式的に表現したものである。黒色で表示されたバルブは、閉状態であることを意味する。 Assuming a full-scale blast furnace having an inner volume of 5000 m 3 and 40 tuyeres around it, pipes (branch pipes: equivalent to branch pipes) from the distributor (distributor) to the tuyeres are assumed. A pipe flow control valve, a three-way valve, and a branch pipe flow meter were installed on the pipe from the upstream side. 3 to 5 schematically illustrate the device configuration and the gas flow in the present embodiment and the reference example. A valve displayed in black means a closed state.
図３は、本実施例による、（通常時における、）微粉炭の吹き込みの状態を示した図である。図３に示すように、微粉炭を気流輸送するための流体として空気を用い、平常運転時を想定した流量として１００Ｎｍ３/ｈ（支管１本あたり）とした。微粉炭の量としては、固気比が７．８ｋｇ／ｋｇなるように設定した。吹き込み試験用の微粉炭として、流量低下や詰まりが比較的発生しやすい性状の微粉炭を用いた。さらに、実際の操業で詰まりの原因となったことのある木片、ウエス、ビニール、糸くず等の異物を模擬したものを微粉炭に混合して、吹き込み試験に用いた。これは流量低下や詰まりの発生のしやすさ（またはしにくさ）を加速試験的に評価するためである。
設置した支管流量調整弁で前記の流量を得るための弁開度は、約４０％であった。このときの支管流量調整弁での圧力損失は、おおよそ０．１ＭＰａであった。
図４は、本実施例による、微粉炭の詰まりを解消するためのパージを行っている状態を示した図である。図４に示すように、対象となる羽口につながる支管流量調整弁の弁開度を４０％から全開（１００％）にすると（このとき対象外となる羽口につながる支管流量調整弁の弁解度は４０％のままとした）、流量が１７０Ｎｍ３/ｈ（支管１本あたり）となり、大幅に流量を増加できることが確認された。
FIG. 3 is a diagram showing a state of pulverized coal injection (at a normal time) according to the present embodiment. As shown in FIG. 3, air was used as a fluid for pneumatically transporting pulverized coal, and the flow rate was set to 100 Nm 3 / h (per branch pipe) assuming normal operation. The amount of pulverized coal was set such that the solid-gas ratio was 7.8 kg / kg. As the pulverized coal for the blowing test, pulverized coal having a property in which a decrease in flow rate and clogging are relatively likely to occur was used. Furthermore, what simulated foreign materials such as wood chips, rags, vinyl, and lint that had caused clogging in actual operation was mixed with pulverized coal and used for a blowing test. This is to evaluate the easiness (or difficulty) of the decrease in flow rate and the occurrence of clogging in an accelerated test.
The valve opening for obtaining the flow rate with the installed branch pipe flow control valve was about 40%. The pressure loss at the branch pipe flow control valve at this time was approximately 0.1 MPa.
FIG. 4 is a diagram showing a state in which purging for eliminating clogging of pulverized coal is performed according to the present embodiment. As shown in FIG. 4, when the valve opening of the branch pipe flow control valve connected to the target tuyere is changed from 40% to full open (100%) (at this time, the valley of the branch pipe flow control valve connected to the non-target tuyere is released). The degree was kept at 40%), and the flow rate was 170 Nm 3 / h (per branch pipe), and it was confirmed that the flow rate could be greatly increased.
支管の流量低下や詰まりを模擬的に再現するために、支管出口（羽口の直前部に相当）に微粉炭による閉塞物を充填した。このときの流量は６０Ｎｍ３/ｈ（支管１本あたり）となった。この流量低下や詰まりを解消するために、図４に示すように、支管流量調整弁の弁開度を瞬時（１秒以内）に４０％から全開（１００％）にすると、流量は増加し、流量低下や詰まりは解消した。その後、弁開度を平常運転時の開度（４０％）まで戻し（図３参照）、微粉炭の流量制御（目標微粉炭吹き込み量と等しくする）を再開した。流量低下や詰まりの解消のために弁開度を全開にし、流量低下や詰まり解消確認後、平常運転時の弁開度に戻し、通常時の微粉炭の供給が開始できるようになるまでの時間は、数十秒以内であった。 In order to simulate the decrease in flow rate and clogging of the branch pipe, the outlet of the branch pipe (corresponding to the part immediately before the tuyere) was filled with an obstruction made of pulverized coal. The flow rate at this time was 60 Nm 3 / h (per branch pipe). As shown in FIG. 4, when the valve opening of the branch pipe flow control valve is instantaneously (within one second) changed from 40% to full open (100%) in order to eliminate the flow rate decrease and blockage, the flow rate increases. Flow rate reduction and clogging have been resolved. Thereafter, the valve opening was returned to the opening during normal operation (40%) (see FIG. 3), and the pulverized coal flow control (equal to the target pulverized coal injection amount) was restarted. Time to fully open the valve to eliminate the flow rate drop and clogging, return to the valve opening during normal operation after confirming the flow rate drop and clogging clearance, and start the normal pulverized coal supply Was within tens of seconds.
なお、参考例として、上記と同様の模擬閉塞物で詰まりを生じさせた場合に、図５に示すように、三方弁の流れ方向を変更し、微粉炭の供給を停止して、エアパージを１２０Ｎｍ３/ｈ（支管１本あたり）を行った。この場合でも、模擬閉塞物が支管出口から排出され、流量低下や詰まりは解消した。三方弁を切り替えて、エアパージによる詰まり解消を行って、通常時の微粉炭の供給が再開できるようになるには、数分の時間を要した。 As a reference example, when clogging was caused by the same simulated obstruction as described above, as shown in FIG. 5, the flow direction of the three-way valve was changed, the supply of pulverized coal was stopped, and air purge was performed at 120 Nm. 3 / h (per branch tube) was performed. Even in this case, the simulated obstruction was discharged from the branch pipe outlet, and the decrease in flow rate and the clogging were resolved. It took several minutes for the three-way valve to be switched, to clear the clogging by air purge, and to resume the supply of pulverized coal during normal times.
Claims (4)
前記支管流量計で前記微粉炭の吹き込み量低下及び／または詰まりが確認された場合に、前記支管流量調整弁の開度を全開とすることを特徴とする、微粉炭吹き込み方法。 In the pulverized coal injection method, pulverized coal to be pneumatically transported is branched into branch pipes by a distributor and blown into a blast furnace through tuyeres, where a branch pipe flow control valve and a branch pipe flow meter are installed in each of the branch pipes. ,
The pulverized coal blowing method, wherein when the pulverized coal blowing amount is confirmed to be reduced and / or clogged by the branch pipe flow meter, the opening of the branch pipe flow control valve is fully opened.
前記支管から前記羽口への微粉炭吹き込み量を、前記支管流量計を用いて、監視し、
前記微粉炭吹き込み量が、平常運転時の目標微粉炭吹き込み量と等しくなるように、前記支管流量調整弁の弁開度を調整することを特徴とする、請求項１記載の微粉炭吹き込み方法。 During normal operation, the opening degree of the branch pipe flow control valve is set so that the pressure loss at the branch pipe flow control valve falls within a predetermined range,
The amount of pulverized coal blown from the branch pipe to the tuyere is monitored using the branch pipe flow meter,
2. The pulverized coal injection method according to claim 1, wherein the valve opening of the branch pipe flow control valve is adjusted such that the pulverized coal injection amount is equal to a target pulverized coal injection amount during normal operation. 3.
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| CN114350863A (en) * | 2021-12-24 | 2022-04-15 | 鞍钢集团工程技术有限公司 | Method for blowing coal powder into blast furnace |
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