JP2012188742A - Method for operating blast furnace - Google Patents

Method for operating blast furnace Download PDF

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JP2012188742A
JP2012188742A JP2011279954A JP2011279954A JP2012188742A JP 2012188742 A JP2012188742 A JP 2012188742A JP 2011279954 A JP2011279954 A JP 2011279954A JP 2011279954 A JP2011279954 A JP 2011279954A JP 2012188742 A JP2012188742 A JP 2012188742A
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pulverized coal
blast furnace
less
lance
gas
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JP5923967B2 (en
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Daiki Fujiwara
大樹 藤原
Akinori Murao
明紀 村尾
Shiro Watakabe
史朗 渡壁
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JFE Steel Corp
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JFE Steel Corp
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Priority to JP2011279954A priority Critical patent/JP5923967B2/en
Application filed by JFE Steel Corp filed Critical JFE Steel Corp
Priority to TW101106750A priority patent/TWI487791B/en
Priority to KR1020147019598A priority patent/KR101629123B1/en
Priority to BR112014015336-1A priority patent/BR112014015336B1/en
Priority to PCT/JP2012/055893 priority patent/WO2013094230A1/en
Priority to EP23184934.0A priority patent/EP4283233A1/en
Priority to EP12860851.0A priority patent/EP2796566B1/en
Priority to EP18181898.0A priority patent/EP3421618B1/en
Priority to IN1261KON2014 priority patent/IN2014KN01261A/en
Priority to AU2012355194A priority patent/AU2012355194B2/en
Priority to CN201280063993.6A priority patent/CN104024440B/en
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    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02PCLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00Technologies related to metal processing
    • Y02P10/20Recycling

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  • Manufacture Of Iron (AREA)

Abstract

PROBLEM TO BE SOLVED: To provide a method for operating a blast furnace capable of enhancing a combustion temperature, and, as a result, reducing discharged CO.SOLUTION: A lance 4 for injecting fuel from a tuyere 3 is formed into a double tube to inject fine powdery coal from an inner tube 21 of the double-tube lance 4, and to blow oxygen from an outer tube 22 of the double-tube lance 4. A notch 23 is provided in a blowing end of the inner tube 21 of the double-tube lance 4 to set an oxygen concentration of a gas consisting of a carrier gas of the fine powdery coal and the gas blown from the outer tube to 35 vol.% or more. Thereby, the combustion temperature can be raised even in an operation of a high fine powdery coal ratio in which a volatile matter concentration of the fine powdery coal is 25 mass% or less, and a fine powdery coal ratio is 150 kg/t-pig iron or more, and, as a result, discharged COcan be reduced, and oxygen unit consumption can be suppressed by setting the oxygen concentration to less than 70 vol.%. Moreover, the combustion efficiency is further improved by providing a plurality of notches 23 at an even interval in the circumferential direction of the inner tube 21 of the double-tube lance 4.

Description

本発明は、高炉羽口から微粉炭を吹込んで、燃焼温度を上昇させることにより生産性の向上及び排出CO2の低減を図る高炉の操業方法に関するものである。 The present invention relates to a method for operating a blast furnace in which pulverized coal is blown from a blast furnace tuyere and the combustion temperature is raised to improve productivity and reduce exhaust CO 2 .

近年、炭酸ガス排出量の増加による地球温暖化が問題となっており、製鉄業においても排出CO2の抑制は重要な課題である。高炉は、主にコークス及び羽口から吹込む微粉炭を還元材として使用しており、事前処理により生じる炭酸ガス排出量の差から、できるだけコークスよりも微粉炭を使用することが排出CO2の抑制につながる。例えば、下記特許文献1では、微粉炭比が150kg/t−銑鉄以上、揮発分が25mass%以下の微粉炭を用い、羽口から燃料を吹込むためのランスに微粉炭と酸素を供給し、ランス中の酸素濃度を70vol%以上とすることで、燃焼効率を向上することができるとしている。また、この特許文献1では、ランスが単管である場合には、酸素と微粉炭の混合物をランスから吹込みランスが二重管である場合には、二重管ランスの内側管から微粉炭を吹込み、二重管ランスの外側管から酸素を吹込むことも提案されている。なお、微粉炭比とは、銑鉄1tあたりに使用される微粉炭の質量である。 In recent years, global warming due to an increase in carbon dioxide emissions has become a problem, and the suppression of emitted CO 2 is an important issue even in the steel industry. Blast furnace, mainly we use blown pulverized coal coke and tuyere as reducing agent, the difference in carbon dioxide emissions generated by the pre-treatment, the use of pulverized coal than possible coke discharge CO 2 Leads to suppression. For example, in Patent Document 1 below, pulverized coal with a pulverized coal ratio of 150 kg / t-pig iron or more and volatile content of 25 mass% or less is used, and pulverized coal and oxygen are supplied to a lance for injecting fuel from the tuyere. Combustion efficiency can be improved by setting the oxygen concentration of the gas to 70 vol% or more. In Patent Document 1, when the lance is a single pipe, a mixture of oxygen and pulverized coal is blown from the lance. When the lance is a double pipe, the pulverized coal is injected from the inner pipe of the double pipe lance. It has also been proposed to blow oxygen from the outer tube of the double tube lance. The pulverized coal ratio is the mass of pulverized coal used per 1 ton of pig iron.

また、下記特許文献2では、二重管ランスの外側管に凹凸を設けて微粉炭を分散させ、微粉炭と酸素の反応を促進するようにしている。
また、下記特許文献3では、二重管の内側管から微粉炭を吹込み、二重管ランスの外側管から酸素を吹込む場合に、二重管ランスの内側管を外側管より短くして、つまり内側管の微粉炭吹出し先端部を外側管の酸素吹出し先端部より吹出し方向手前側として微粉炭と酸素の接触性を向上している。
Moreover, in the following patent document 2, irregularities are provided on the outer tube of the double tube lance to disperse the pulverized coal so as to promote the reaction between the pulverized coal and oxygen.
In Patent Document 3 below, when pulverized coal is blown from the inner pipe of the double pipe and oxygen is blown from the outer pipe of the double pipe lance, the inner pipe of the double pipe lance is made shorter than the outer pipe. That is, the contact property between the pulverized coal and oxygen is improved by using the pulverized coal blowing tip of the inner tube as the front side in the blowing direction from the oxygen blowing tip of the outer tube.

特許第4074467号公報Japanese Patent No. 4074467 韓国特許公開公報2002−00047359Korean Patent Publication No. 2002-047359 特開平6−100912号公報Japanese Patent Application Laid-Open No. 6-10092

羽口には大量の空気が送風されているものの、ランスは高温に晒される恐れがあり、前記特許文献1に記載されるように、単管ランスに高濃度の酸素と微粉炭の混合物を供給するのは安全面から現実的でない。また、更なる排出CO2の低減が要求されていることから、例えば微粉炭比を170kg/t−銑鉄以上とすることが望まれているが、微粉炭比が170kg/t−銑鉄以上の高微粉炭比では、前記特許文献1に記載されるように、単に二重管ランスの内側管から微粉炭を吹込み、外側管から酸素を吹込んでも、燃焼温度が飽和してしまって燃焼効率が高くならない。 Although a large amount of air is blown through the tuyere, the lance may be exposed to high temperatures, and as described in Patent Document 1, a mixture of high-concentration oxygen and pulverized coal is supplied to the single tube lance. This is not practical from a safety standpoint. Further, since further reduction of exhausted CO 2 is required, for example, it is desired that the pulverized coal ratio be 170 kg / t-pig iron or higher, but the pulverized coal ratio is higher than 170 kg / t-pig iron. In the pulverized coal ratio, as described in Patent Document 1, even if pulverized coal is simply blown from the inner pipe of the double pipe lance and oxygen is blown from the outer pipe, the combustion temperature is saturated and combustion efficiency is increased. Does not increase.

また、二重管ランスの外側管に流れるガスは当該外側管の冷却の役目も担っているため、前記特許文献2に記載されるように、外側管に設けられた凹凸のようにガスの流れを妨げるものが存在する場合、流れが弱い部分に熱負荷がかかり、割れや溶損などの損耗が生じる可能性がある。このような損耗が発生した場合、逆火やランスの詰まりなどを誘発する恐れがある。また、微粉炭量が増加すると、内側管から噴出する微粉炭により凸部の摩耗発生を避けられない問題がある。   In addition, since the gas flowing in the outer tube of the double tube lance also plays a role of cooling the outer tube, as described in Patent Document 2, the flow of gas is similar to the unevenness provided in the outer tube. If there is something that hinders the heat flow, a heat load is applied to the portion where the flow is weak, and wear such as cracking or melting may occur. If such wear occurs, there is a risk of causing backfire or clogging of the lance. Moreover, when the amount of pulverized coal increases, there is a problem that the occurrence of wear on the convex portions cannot be avoided due to the pulverized coal ejected from the inner pipe.

また、前記特許文献3に記載されるように、二重管ランスの内側管の先端部を単に外側管より短くしただけでは、微粉炭と酸素の接触性は向上しても、酸素の流れによって微粉炭の分散が抑制され、十分な燃焼性向上効果が得られない。
本発明は、上記のような問題点に着目してなされたものであり、燃焼温度を向上することができ、その結果、排出CO2の低減を可能とする高炉操業方法を提供することを目的とするものである。
Further, as described in Patent Document 3, even if the tip of the inner pipe of the double pipe lance is simply made shorter than the outer pipe, the contact between pulverized coal and oxygen is improved, The dispersion of pulverized coal is suppressed, and a sufficient combustibility improvement effect cannot be obtained.
The present invention has been made paying attention to the above-mentioned problems, and an object of the present invention is to provide a blast furnace operating method capable of improving the combustion temperature and, as a result, reducing the exhaust CO 2. It is what.

上記課題を解決するために、本発明のうち請求項1に係る発明は、揮発分が25mass%以下の微粉炭を準備し、羽口から微粉炭と支燃性ガスを吹込むための、内側管と外側管とを有する二重管ランスを準備し、前記羽口から熱風を吹込み、前記二重管ランスの内側管の吹込み先端部に、軸方向に凹んだ切欠きを周方向に複数設け、当該内側管から150kg/t−銑鉄以上の微粉炭比で前記微粉炭を搬送ガスと共に吹込み、前記二重管ランスの外側管から支燃性ガスを吹込み、前記搬送ガスと支燃性ガスとからなるガスの酸素濃度が35vol%以上である、高炉操業方法である。   In order to solve the above-mentioned problems, the invention according to claim 1 of the present invention provides an inner pipe for preparing pulverized coal having a volatile content of 25 mass% or less and blowing pulverized coal and combustion-supporting gas from the tuyere. A double tube lance having an outer tube is prepared, hot air is blown from the tuyere, and a plurality of notches recessed in the axial direction are provided in the circumferential direction at the blowing tip of the inner tube of the double tube lance The pulverized coal is blown together with the carrier gas at a pulverized coal ratio of 150 kg / t-pig iron or more from the inner pipe, and the combustion-supporting gas is blown from the outer pipe of the double-pipe lance. This is a blast furnace operating method in which the oxygen concentration of the gas composed of the gas is 35 vol% or more.

また、本発明のうち請求項2に係る発明は、前記切欠きは、前記二重管ランスの内側管の先端部周方向に等間隔に設けられている請求項1に記載の高炉操業方法である。
また、本発明のうち請求項3に係る発明は、前記切欠きの幅は、前記二重管ランスの内側管の内周の長さに対する全ての切欠きの幅の計の比で0を超え、0.5以下とする請求項2に記載の高炉操業方法である。
Moreover, the invention which concerns on Claim 2 among this invention is the blast furnace operating method of Claim 1 with which the said notch is provided at equal intervals in the front-end | tip part circumferential direction of the inner side pipe | tube of the said double pipe lance. is there.
In the invention according to claim 3 of the present invention, the width of the notch exceeds 0 in the ratio of the total width of all the notches to the inner circumference of the inner tube of the double pipe lance. The blast furnace operating method according to claim 2, wherein the blast furnace is 0.5 or less.

また、本発明のうち請求項4に係る発明は、前記切欠きの幅は、前記二重管ランスの内側管の内周の長さに対する全ての切欠きの幅の計の比で0.05以上、0.3以下とする請求項3に記載の高炉操業方法である。
また、本発明のうち請求項5に係る発明は、前記切欠きの幅は、前記二重管ランスの内側管の内周の長さに対する全ての切欠きの幅の計の比で0.1以上、0.2以下とする請求項4に記載の高炉操業方法である。
In the invention according to claim 4 of the present invention, the width of the notch is 0.05 as a ratio of the total width of all the notches to the inner peripheral length of the inner tube of the double tube lance. The blast furnace operating method according to claim 3, wherein the blast furnace is 0.3 or less.
In the invention according to claim 5 of the present invention, the width of the notch is 0.1 as a ratio of the total width of all the notches with respect to the inner peripheral length of the inner tube of the double tube lance. The blast furnace operating method according to claim 4, wherein the blast furnace is 0.2 or less.

また、本発明のうち請求項6に係る発明は、前記切欠きの深さは、0mmを超え、12mm以下とする請求項2に記載の高炉操業方法である。
また、本発明のうち請求項7に係る発明は、前記切欠きの深さは、2mm以上、10mm以下とする請求項6に記載の高炉操業方法である。
また、本発明のうち請求項8に係る発明は、前記切欠きの深さは、3mm以上、7mm以下とする請求項7に記載の高炉操業方法である。
Moreover, the invention which concerns on Claim 6 among this invention is the blast furnace operating method of Claim 2 which makes the depth of the said notch exceed 0 mm and 12 mm or less.
Moreover, the invention which concerns on Claim 7 among this invention is the blast furnace operating method of Claim 6 which makes the depth of the said notch 2 mm or more and 10 mm or less.
Moreover, the invention which concerns on Claim 8 among this invention is a blast furnace operating method of Claim 7 which makes the depth of the said notch 3 mm or more and 7 mm or less.

また、本発明のうち請求項9に係る発明は、前記二重管ランスの内側管の内周長を1つの切欠きの幅で除したときの整数部を最大切欠き数とした場合、前記切欠きの数は、最大切欠き数に対する切欠き数の比で0を超え、0.8以下とする請求項2に記載の高炉操業方法である。
また、本発明のうち請求項10に係る発明は、前記切欠きの数は、前記最大切欠き数に対する切欠き数の比で0.1以上、0.6以下とする請求項9に記載の高炉操業方法である。
In the invention according to claim 9 of the present invention, when the integer part when the inner peripheral length of the inner pipe of the double pipe lance is divided by the width of one notch is the maximum notch number, The number of notches is a blast furnace operating method according to claim 2, wherein the ratio of the number of notches to the maximum number of notches exceeds 0 and is 0.8 or less.
Moreover, the invention which concerns on Claim 10 among this invention WHEREIN: The number of the said notches is 0.1 or more and 0.6 or less by ratio of the number of notches with respect to the said maximum number of notches. It is a blast furnace operation method.

また、本発明のうち請求項11に係る発明は、前記切欠きの数は、前記最大切欠き数に対する切欠き数の比で0.2以上、0.5以下とする請求項10に記載の高炉操業方法である。
また、本発明のうち請求項12に係る発明は、前記支燃性ガスは酸素であり、送風に富化する酸素の一部を前記二重管ランスの外側管から吹込む請求項1に記載の高炉操業方法である。
Moreover, the invention which concerns on Claim 11 among this invention sets the number of the said notches to 0.2 or more and 0.5 or less by ratio of the number of notches with respect to the said maximum number of notches. It is a blast furnace operation method.
Further, in the invention according to claim 12 of the present invention, the combustion-supporting gas is oxygen, and a part of oxygen enriched in blowing is blown from the outer pipe of the double pipe lance. This is the blast furnace operation method.

また、本発明のうち請求項13に係る発明は、前記微粉炭が、3mass%以上25mass%以下の揮発分を有する請求項1に記載の高炉操業方法である。
また、本発明のうち請求項14に係る発明は、前記二重管ランスの外側管から吹込まれる支燃性ガスが、20〜120m/secの出口流速を有する請求項1に記載の高炉操業方法である。
Moreover, the invention which concerns on Claim 13 among this invention is a blast furnace operating method of Claim 1 in which the said pulverized coal has a volatile matter of 3 mass% or more and 25 mass% or less.
The invention according to claim 14 of the present invention is the blast furnace operation according to claim 1, wherein the combustion-supporting gas blown from the outer pipe of the double pipe lance has an outlet flow velocity of 20 to 120 m / sec. Is the method.

また、本発明のうち請求項15に係る発明は、前記微粉炭比が170kg/t−銑鉄以上である請求項1に記載の高炉操業方法である。
また、本発明のうち請求項16に係る発明は、前記微粉炭比が170kg/t−銑鉄以上であり、前記搬送ガスと支燃性ガスとからなるガスの酸素濃度が35vol%以上70vol%未満である、請求項1に記載の高炉操業方法である。
Moreover, the invention which concerns on Claim 15 among this invention is a blast furnace operating method of Claim 1 whose said pulverized coal ratio is 170 kg / t-pig iron or more.
In the invention according to claim 16 of the present invention, the pulverized coal ratio is 170 kg / t-pig iron or more, and the oxygen concentration of the gas composed of the carrier gas and the combustion-supporting gas is 35 vol% or more and less than 70 vol%. It is a blast furnace operating method of Claim 1 which is.

また、本発明のうち請求項17に係る発明は、前記搬送ガスと支燃性ガスとからなるガスの酸素濃度が40vol%以上65vol%以下である請求項16に記載の高炉操業方法である。
また、本発明のうち請求項18に係る発明は、前記搬送ガスと支燃性ガスとからなるガスの酸素濃度が45vol%以上60vol%以下である請求項17に記載の高炉操業方法である。
Moreover, the invention which concerns on Claim 17 among this invention is a blast furnace operating method of Claim 16 whose oxygen concentration of the gas which consists of the said carrier gas and combustion support gas is 40 vol% or more and 65 vol% or less.
Moreover, the invention which concerns on Claim 18 among this invention is a blast furnace operating method of Claim 17 whose oxygen concentration of the gas which consists of the said carrier gas and combustion support gas is 45 vol% or more and 60 vol% or less.

また、本発明のうち請求項19に係る発明は、前記微粉炭比が170kg/t−銑鉄以上300kg/t−銑鉄以下である請求項15に記載の高炉操業方法である。
また、本発明のうち請求項20に係る発明は、前記微粉炭比が170kg/t−銑鉄以上300kg/t−銑鉄以下である請求項16に記載の高炉操業方法である。
また、本発明のうち請求項21に係る発明は、前記搬送ガスと支燃性ガスとからなるガスの酸素濃度が35vol%以上70vol%未満である請求項1に記載の高炉操業方法である。
Moreover, the invention which concerns on Claim 19 among this invention is a blast furnace operating method of Claim 15 whose said pulverized coal ratio is 170 kg / t-pig iron or more and 300 kg / t-pig iron or less.
Moreover, the invention which concerns on Claim 20 among this invention is a blast furnace operating method of Claim 16 whose said pulverized coal ratio is 170 kg / t-pig iron or more and 300 kg / t-pig iron or less.
Moreover, the invention which concerns on Claim 21 among this invention is a blast furnace operating method of Claim 1 whose oxygen concentration of the gas which consists of the said carrier gas and combustion support gas is 35 vol% or more and less than 70 vol%.

また、本発明のうち請求項22に係る発明は、前記搬送ガスと支燃性ガスとからなるガスの酸素濃度が40vol%以上65vol%以下である請求項21に記載の高炉操業方法である。
また、本発明のうち請求項23に係る発明は、前記搬送ガスと支燃性ガスとからなるガスの酸素濃度が45vol%以上60vol%以下である請求項22に記載の高炉操業方法である。
The invention according to claim 22 of the present invention is the blast furnace operating method according to claim 21, wherein the oxygen concentration of the gas composed of the carrier gas and the combustion-supporting gas is 40 vol% or more and 65 vol% or less.
Moreover, the invention which concerns on Claim 23 among this invention is a blast furnace operating method of Claim 22 whose oxygen concentration of the gas which consists of the said carrier gas and combustion support gas is 45 vol% or more and 60 vol% or less.

また、本発明のうち請求項24に係る発明は、前記微粉炭比が150kg/t−銑鉄以上300kg/t−銑鉄以下である請求項1に記載の高炉操業方法である。
また、本発明のうち請求項25に係る発明は、前記微粉炭比が150kg/t−銑鉄以上170kg/t−銑鉄未満である請求項1に記載の高炉操業方法である。
また、本発明のうち請求項26に係る発明は、前記微粉炭比が150kg/t−銑鉄以上170kg/t−銑鉄未満であり、前記搬送ガスと支燃性ガスとからなるガスの酸素濃度が35vol以上70vol%未満である、請求項1に記載の高炉操業方法である。
Moreover, the invention which concerns on Claim 24 among this invention is a blast furnace operating method of Claim 1 whose said pulverized coal ratio is 150 kg / t-pig iron or more and 300 kg / t-pig iron or less.
Moreover, the invention which concerns on Claim 25 among this invention is a blast furnace operating method of Claim 1 whose said pulverized coal ratio is 150 kg / t-pig iron or more and less than 170 kg / t-pig iron.
In the invention according to claim 26 of the present invention, the ratio of the pulverized coal is 150 kg / t-pig iron or more and less than 170 kg / t-pig iron, and the oxygen concentration of the gas composed of the carrier gas and the combustion-supporting gas is It is a blast furnace operating method of Claim 1 which is 35 vol or more and less than 70 vol%.

また、本発明のうち請求項27に係る発明は、前記微粉炭に、廃プラスチック、廃棄物固形燃料、有機性資源、廃材、CDQ集塵コークスからなるグループのうち、少なくとも1つを加える請求項1乃至26の何れか一項に記載の高炉操業方法である。
また、本発明のうち請求項28に係る発明は、前記微粉炭の割合を80mass%以上として、前記廃プラスチック、廃棄物固形燃料、有機性資源、廃材、CDQ集塵コークスを使用する請求項27に記載の高炉操業方法である。
Moreover, the invention which concerns on Claim 27 among this invention is a claim which adds at least 1 out of the group which consists of a waste plastic, waste solid fuel, an organic resource, a waste material, and CDQ dust collection coke to the said pulverized coal. It is a blast furnace operating method as described in any one of 1-26.
Further, the invention according to claim 28 of the present invention uses the waste plastic, waste solid fuel, organic resources, waste material, CDQ dust collecting coke, wherein the ratio of the pulverized coal is 80 mass% or more. The blast furnace operating method described in 1.

而して、本発明の高炉操業方法によれば、羽口から燃料を吹込むためのランスを二重管とし、二重管ランスの内側管から微粉炭を搬送ガスと共に吹込むと共に、二重管ランスの外側管から支燃性ガスを吹込み、二重管ランスの内側管の吹込み先端部に切欠きを設け、二重管ランス中の搬送ガスと支燃性ガスとからなるガスの酸素濃度を35vol%以上とすることにより、微粉炭の揮発分が25mass%以下で且つ微粉炭比が150kg/t−銑鉄以上の高微粉炭比操業であっても燃焼温度を高めることができ、その結果、排出CO2を低減することができる。また、微粉炭比が170kg/t−銑鉄以上である場合には、二重管ランス中の搬送ガスと支燃性ガスとからなるガスの酸素濃度を70vol%未満とすることにより、酸素などの支燃性ガスの原単位を抑制することができる。 Thus, according to the blast furnace operating method of the present invention, the lance for injecting fuel from the tuyere is a double pipe, pulverized coal is blown together with the carrier gas from the inner pipe of the double pipe lance, and the double pipe lance Of the gas consisting of the carrier gas and the combustion-supporting gas in the double-pipe lance. When the volatile content of pulverized coal is 25 mass% or less and the pulverized coal ratio is 150 kg / t-pig iron or higher, the combustion temperature can be increased. , Exhaust CO 2 can be reduced. In addition, when the pulverized coal ratio is 170 kg / t-pig iron or more, the oxygen concentration of the gas composed of the carrier gas and the combustion-supporting gas in the double-pipe lance is less than 70 vol%, so that The basic unit of the combustion-supporting gas can be suppressed.

また、切欠きを二重管ランスの内側管の先端部周方向に等間隔に複数設けることにより、微粉炭及び支燃性ガスの拡散を促進し、燃焼効率をより一層向上することができる。
また、送風に富化する酸素の一部を支燃性ガスとして二重管ランスの外側管から吹込むことにより、高炉内のガスバランスを損なうことがなく、酸素の過剰供給を回避することができる。
In addition, by providing a plurality of notches at equal intervals in the circumferential direction of the tip of the inner pipe of the double pipe lance, diffusion of pulverized coal and combustion-supporting gas can be promoted, and combustion efficiency can be further improved.
In addition, by blowing a part of oxygen enriched in the blast from the outer pipe of the double pipe lance as a combustion-supporting gas, it is possible to avoid excessive supply of oxygen without impairing the gas balance in the blast furnace. it can.

本発明の高炉操業方法が適用された高炉の一実施形態を示す縦断面図である。It is a longitudinal cross-sectional view which shows one Embodiment of the blast furnace to which the blast furnace operating method of this invention was applied. 図1のランスから微粉炭だけを吹込んだときの燃焼状態の説明図である。It is explanatory drawing of a combustion state when only pulverized coal is blown in from the lance of FIG. 図2の微粉炭の燃焼メカニズムの説明図である。It is explanatory drawing of the combustion mechanism of the pulverized coal of FIG. 微粉炭と酸素を吹込んだときの燃焼メカニズムの説明図である。It is explanatory drawing of a combustion mechanism when pulverized coal and oxygen are blown. 燃焼実験装置の説明図である。It is explanatory drawing of a combustion experiment apparatus. 微粉炭流の濃化の説明図である。It is explanatory drawing of concentration of a pulverized coal flow. 図1のランスの吹込み先端部の詳細図である。It is detail drawing of the blowing front-end | tip part of the lance of FIG. 図7のランス及びストレート管からなるランスの微粉炭流の説明図である。It is explanatory drawing of the pulverized coal flow of the lance which consists of a lance and a straight pipe of FIG. 微粉炭比が150kg/t−銑鉄以上170kg/t−銑鉄未満であるときのランス供給ガス中の酸素濃度と燃焼率の関係を示すグラフである。It is a graph which shows the relationship between the oxygen concentration in a lance supply gas, and a combustion rate when pulverized coal ratio is 150 kg / t-pig iron or more and less than 170 kg / t-pig iron. 微粉炭比が170kg/t−銑鉄以上であるときのランス供給ガス中の酸素濃度と燃焼率の関係を示すグラフである。It is a graph which shows the relationship between the oxygen concentration in a lance supply gas when a pulverized coal ratio is 170 kg / t- pig iron or more, and a combustion rate. 内側管の径方向から見たときの切欠きの形状の説明図である。It is explanatory drawing of the shape of a notch when it sees from the radial direction of an inner side pipe | tube. 切欠きの先端中心と下端中心のなす角度θの説明図である。It is explanatory drawing of angle (theta) which the front-end | tip center and notch center of a notch make. 酸素と微粉炭の接触面積及び微粉炭の分散幅の実験の説明図である。It is explanatory drawing of experiment of the contact area of oxygen and pulverized coal, and the dispersion width of pulverized coal. 切欠きの幅を変更したときの酸素と微粉炭の接触面積及び微粉炭の分散幅の説明図である。It is explanatory drawing of the contact area of oxygen and pulverized coal when the width | variety of a notch is changed, and the dispersion | distribution width | variety of pulverized coal. 切欠きの深さを変更したときの酸素と微粉炭の接触面積及び微粉炭の分散幅の説明図である。It is explanatory drawing of the contact area of oxygen and pulverized coal when the depth of a notch is changed, and the dispersion width of pulverized coal. 切欠きの数を変更したときの酸素と微粉炭の接触面積及び微粉炭の分散幅の説明図である。It is explanatory drawing of the contact area of oxygen and pulverized coal when the number of notches is changed, and the dispersion width of pulverized coal. 切欠きの形状が四角形である場合と三角形である場合で、それらの切欠きの幅を変更したときの酸素と微粉炭の接触面積及び微粉炭の分散幅の説明図である。It is explanatory drawing of the contact area of oxygen and pulverized coal, and the dispersion | distribution width | variety of pulverized coal when the shape of a notch is a square and when it is a triangle, when the width of those notches is changed. ランスの出口流速とランス表面温度の関係を示す説明図である。It is explanatory drawing which shows the relationship between the exit flow velocity of a lance, and the lance surface temperature.

次に、本発明の高炉操業方法の一実施形態について図面を参照しながら説明する。
図1は、本実施形態の高炉操業方法が適用された高炉の全体図である。図に示すように、高炉1の羽口3には、熱風を送風するための送風管2が接続され、この送風管2を貫通してランス4が設置されている。羽口3の熱風送風方向先方のコークス堆積層には、レースウエイ5と呼ばれる燃焼空間が存在し、主として、この燃焼空間で還元材の燃焼、ガス化が行われる。
Next, an embodiment of the blast furnace operating method of the present invention will be described with reference to the drawings.
FIG. 1 is an overall view of a blast furnace to which the blast furnace operating method of the present embodiment is applied. As shown in the figure, a blast pipe 2 for blowing hot air is connected to the tuyere 3 of the blast furnace 1, and a lance 4 is installed through the blast pipe 2. A combustion space called a raceway 5 exists in the coke deposit layer in the hot air blowing direction ahead of the tuyere 3, and the reducing material is mainly combusted and gasified in this combustion space.

図2には、ランス4から固体還元材として微粉炭6だけを吹込んだときの燃焼状態を示す。ランス4から羽口3を通過し、レースウエイ5内に吹込まれた微粉炭6は、コークス7と共に、その揮発分と固定炭素が燃焼し、揮発分が放出されて残った、一般にチャーと呼ばれる炭素と灰分の集合体は、レースウエイから未燃チャー8として排出される。羽口3の熱風送風方向先方における熱風速度は約200m/secであり、ランス4の先端からレースウエイ5内における酸素の存在領域は約0.3〜0.5mとされているので、実質的に1/1000秒のレベルで微粉炭粒子の昇温及び酸素との接触効率(分散性)の改善が必要となる。   FIG. 2 shows a combustion state when only pulverized coal 6 is blown from the lance 4 as a solid reducing material. The pulverized coal 6 that has passed through the tuyere 3 from the lance 4 and is blown into the raceway 5 is combusted with coke 7 and its volatile matter and fixed carbon, and the volatile matter is released and is generally called char. The aggregate of carbon and ash is discharged as unburned char 8 from the raceway. The hot air velocity at the tip of the tuyere 3 in the direction of blowing hot air is about 200 m / sec, and the oxygen existing area in the raceway 5 from the tip of the lance 4 is about 0.3 to 0.5 m. In addition, it is necessary to improve the temperature rise of the pulverized coal particles and the contact efficiency (dispersibility) with oxygen at a level of 1/1000 second.

図3は、ランス4から送風管2内に微粉炭(図ではPC:Pulverized Coal)6のみを吹込んだ場合の燃焼メカニズムを示す。羽口3からレースウエイ5内に吹込まれた微粉炭6は、レースウエイ5内の火炎からの輻射伝熱によって粒子が加熱し、更に輻射伝熱、伝導伝熱によって粒子が急激に温度上昇し、300℃以上昇温した時点から熱分解が開始し、揮発分に着火して火炎が形成され、燃焼温度は1400〜1700℃に達する。揮発分が放出してしまうと、前述したチャー8となる。チャー8は、主に固定炭素であるので、燃焼反応と共に、ソリューションロス反応、水素ガスシフト反応といった炭素溶解反応と呼ばれる反応も生じる。   FIG. 3 shows a combustion mechanism when only pulverized coal (PC: Pulverized Coal in the figure) 6 is blown into the blow pipe 2 from the lance 4. The pulverized coal 6 blown into the raceway 5 from the tuyere 3 is heated by the radiant heat transfer from the flame in the raceway 5, and the temperature of the pulverized coal 6 is rapidly increased by the radiant heat transfer and conduction heat transfer. The thermal decomposition starts when the temperature is raised to 300 ° C. or more, and the volatile matter is ignited to form a flame. The combustion temperature reaches 1400 to 1700 ° C. When the volatile matter is released, the above-described char 8 is obtained. Since the char 8 is mainly fixed carbon, a reaction called a carbon dissolution reaction such as a solution loss reaction and a hydrogen gas shift reaction also occurs along with the combustion reaction.

図4は、ランス4から送風管2内に微粉炭6と共に支燃性ガスとして酸素9を吹込んだ場合の燃焼メカニズムを示す。微粉炭6と酸素9の吹込み方法は、単純に平行に吹込んだ場合を示している。なお、図中の二点鎖線は、図3に示した微粉炭のみを吹込んだ場合の燃焼温度を参考に示している。このように微粉炭と酸素を同時に吹込む場合、ランス近傍で微粉炭と酸素との混合が促進され、より早期から微粉炭の燃焼が開始するものと考えられ、これによりランスに近い位置で燃焼温度が更に上昇する。   FIG. 4 shows a combustion mechanism in the case where oxygen 9 is blown as flammable gas together with pulverized coal 6 from the lance 4 into the blower pipe 2. The method of blowing pulverized coal 6 and oxygen 9 simply shows a case of blowing in parallel. In addition, the dashed-two dotted line in a figure has shown the combustion temperature at the time of injecting only the pulverized coal shown in FIG. 3 with reference. When pulverized coal and oxygen are injected at the same time, mixing of pulverized coal and oxygen is promoted in the vicinity of the lance, and combustion of the pulverized coal is considered to start earlier, thereby burning near the lance. The temperature rises further.

このような知見に基づき、図5に示す燃焼実験装置を用いて燃焼実験を行った。高炉内部を模擬して実験炉11内にはコークスが充填されており、覗き窓からレースウエイ15の内部を観察することができる。送風管12にはランス14が差し込まれ、熱風炉から高炉へ送風する熱風として燃焼バーナ13で生じた熱風を実験炉11内に所定の送風量で送風することができるようになっている。また、この送風管12では、送風の酸素富化量を調整することも可能である。ランス14は、微粉炭及び酸素の何れか一方又は双方を送風管12内に吹込むことができる。実験炉11内で生じた排ガスは、サイクロンと呼ばれる分離装置16で排ガスとダストに分離され、排ガスは助燃炉などの排ガス処理設備に送給され、ダストは捕集箱17に捕集される。   Based on such knowledge, a combustion experiment was performed using the combustion experiment apparatus shown in FIG. Simulating the inside of the blast furnace, the experimental furnace 11 is filled with coke, and the inside of the raceway 15 can be observed from the viewing window. A lance 14 is inserted into the blower pipe 12 so that hot air generated in the combustion burner 13 can be blown into the experimental furnace 11 as a hot air to be blown from the hot blast furnace to the blast furnace. Moreover, in this ventilation pipe 12, it is also possible to adjust the oxygen enrichment amount of ventilation. The lance 14 can blow either one or both of pulverized coal and oxygen into the blower pipe 12. The exhaust gas generated in the experimental furnace 11 is separated into exhaust gas and dust by a separator 16 called a cyclone, the exhaust gas is fed to an exhaust gas treatment facility such as an auxiliary combustion furnace, and the dust is collected in a collection box 17.

微粉炭の諸元は、固定炭素(FC:Fixed Carbon)71.4%、揮発分(VM:Volatile Matter)19.5%、灰分(Ash)9.1%である。送風条件は、送風温度1200℃、流量300Nm/h、羽口先風速130m/s、酸素富化6%(酸素濃度27.0%、空気中酸素濃度21%に対し、6.0%の富化)とした。微粉炭吹込み条件として、ランス14には二重管ランスを用い、二重管ランスの内側管から微粉炭を吹込み、二重管ランスの外側管から支燃性ガスとして酸素を吹込んだ。微粉炭は搬送ガスと共に吹込まれ、微粉炭の搬送ガスには窒素を用いた。なお、微粉炭と、微粉炭を搬送する搬送ガスの固気比は、少ないガス量で粉体、つまり微粉炭を輸送する方式(高濃度搬送)では固気比10〜25kg/Nm3、多量のガスで輸送する方式(低濃度搬送)では固気比5〜10kg/Nm3である。搬送ガスには窒素の他、空気を用いることもできる。そして、微粉炭比を100kg/t−銑鉄〜180kg/t−銑鉄の間で種々に変更して、特に微粉炭流の変化について実験した。なお、支燃性ガスとして酸素を吹込む場合には、送風に富化する酸素の一部を用い、炉内に吹込まれる酸素の総量が変化しないようにした。また、支燃性ガスとしては酸素富化空気を用いることもできる。 The specifications of pulverized coal are 71.4% fixed carbon (FC), 19.5% volatile matter (VM), and 9.1% ash (Ash). The air blowing conditions were as follows: air temperature 1200 ° C., flow rate 300 Nm 3 / h, tuyere wind speed 130 m / s, oxygen enrichment 6% (oxygen concentration 27.0%, air oxygen concentration 21%, richness 6.0% ). As a pulverized coal blowing condition, a double pipe lance was used for the lance 14, pulverized coal was blown from the inner pipe of the double pipe lance, and oxygen was blown as a combustion supporting gas from the outer pipe of the double pipe lance. . The pulverized coal was blown together with the carrier gas, and nitrogen was used as the carrier gas for the pulverized coal. The solid-gas ratio between the pulverized coal and the carrier gas that conveys the pulverized coal is 10 to 25 kg / Nm 3 in the solid-gas ratio in the method of transporting the powder, that is, the pulverized coal with a small amount of gas (high concentration conveyance). In the method of transporting with gas (low concentration transport), the solid-gas ratio is 5 to 10 kg / Nm 3 . In addition to nitrogen, air can also be used as the carrier gas. Then, the pulverized coal ratio was variously changed between 100 kg / t-pig iron to 180 kg / t-pig iron, and an experiment was conducted particularly on the change in the pulverized coal flow. In addition, when injecting oxygen as a combustion-supporting gas, a part of oxygen enriched in ventilation was used so that the total amount of oxygen injected into the furnace did not change. Moreover, oxygen-enriched air can also be used as the combustion-supporting gas.

この実験を通じて、本発明者等は更に以下の知見を得た。即ち、二重管ランスの内側管から微粉炭を吹込み、外側管から支燃性ガス、即ち酸素を吹き込む場合、微粉炭の揮発分が25mass%以下であっても、微粉炭比が150kg/t−銑鉄未満の低い微粉炭比操業であれば、酸素濃度を高めることで燃焼温度が高くなる。しかしながら、微粉炭比が150kg/t−銑鉄以上の高微粉炭比操業では、酸素濃度を高めても燃焼温度が高くならない。微粉炭比150kg/t−銑鉄以上の領域では、酸素濃度35vol%程度で燃焼温度が飽和してしまう。これは、後述するように、二重管ランスの内側管から吹込まれる微粉炭が吹込み流の中央部分に集中(濃化ともいう)し、二重管ランスの外側管から吹込まれる酸素と接触しにくくなる、或いは接触しなくなるためである。そこで、本発明では、二重管ランスの内側管から微粉炭を吹込み、外側管から支燃性ガス、例えば酸素を吹込む点は同じであるが、特に内側管の吹込み先端部に切欠きを設け、微粉炭及び支燃性ガスの拡散を促進し、両者を接触し易くして燃焼温度の向上を図る。しかし、一方で、二重管ランスの内側管吹込み先端部に切欠きを設けても、微粉炭比が170kg/t−銑鉄以上の場合には、ランス全体の酸素濃度が70vol%以上になると、やはり燃焼温度は飽和してしまって高くならない。つまり、それ以上、酸素濃度を高めても、酸素原単位が増すだけで燃焼効率は高くはならない。なお、二重管ランスの内側管に切欠きを設ける場合には、邪魔板などの突起物を突設する場合と異なり、突起物に微粉炭が衝突して突起物が損耗するなどのトラブルがない。   Through this experiment, the present inventors further obtained the following knowledge. That is, when pulverized coal is blown from the inner pipe of the double pipe lance and combustion supporting gas, that is, oxygen is blown from the outer pipe, even if the volatile content of the pulverized coal is 25 mass% or less, the pulverized coal ratio is 150 kg / If it is a low pulverized coal ratio operation less than t-pig iron, combustion temperature will become high by raising oxygen concentration. However, in high pulverized coal ratio operation where the pulverized coal ratio is 150 kg / t-pig iron or more, the combustion temperature does not increase even if the oxygen concentration is increased. In the region where the pulverized coal ratio is 150 kg / t-pig iron or more, the combustion temperature is saturated at an oxygen concentration of about 35 vol%. This is because, as will be described later, the pulverized coal blown from the inner pipe of the double pipe lance concentrates (also referred to as concentration) in the central portion of the blow flow, and oxygen blown from the outer pipe of the double pipe lance. This is because it becomes difficult to contact or no longer contacts. Therefore, in the present invention, the pulverized coal is blown from the inner pipe of the double pipe lance and the combustion-supporting gas such as oxygen is blown from the outer pipe. A notch is provided to promote the diffusion of pulverized coal and combustion-supporting gas, making them easy to contact and improving the combustion temperature. However, on the other hand, even if a notch is provided at the inner tube blowing tip of the double tube lance, if the pulverized coal ratio is 170 kg / t-pig iron or more, the oxygen concentration of the entire lance becomes 70 vol% or more. After all, the combustion temperature is saturated and does not increase. In other words, even if the oxygen concentration is further increased, the combustion efficiency does not increase only by increasing the oxygen intensity. Note that when notches are provided in the inner pipe of the double-pipe lance, unlike when projecting projections such as baffle plates, troubles such as pulverized coal colliding with the projections and the projections being worn out can occur. Absent.

図6aには、微粉炭比が150kg/t−銑鉄未満の低微粉炭比操業状態における微粉炭流を示す。実験では、ランスの形状が一定径のストレート管であるため、微粉炭の分散幅はほぼ一定である。このように微粉炭比が低い場合には、分散幅内で微粉炭流はほぼ均一な濃度となる。しかしながら、微粉炭比が150kg/t−銑鉄以上の高微粉炭比操業状態では、図6bに示すように、分散幅内の中央部が濃化し、特に微粉炭比が170kg/t−銑鉄以上の高微粉炭比操業状態では、微粉炭流の中央部が著しく濃化する。酸素は、二重管ランスの外側管から吹込まれるので、微粉炭流の中央部に濃化した微粉炭は酸素と接触せず、未燃焼のまま炉内に持ち込まれ、高炉内の通気を悪化させる。酸素との接触を促進するために酸素の吹込み量を増加しても、図6cに示すように、酸素の吹込み量が一定量以上になると、周囲の酸素流の中央部に一段と微粉炭流が濃化するだけで、酸素との接触は実質的に促進せず、後述するように燃焼温度は飽和する。   FIG. 6a shows the pulverized coal flow in the low pulverized coal ratio operation state where the pulverized coal ratio is less than 150 kg / t-pig iron. In the experiment, since the shape of the lance is a straight pipe having a constant diameter, the dispersion width of the pulverized coal is almost constant. Thus, when the pulverized coal ratio is low, the pulverized coal flow has a substantially uniform concentration within the dispersion width. However, in the high pulverized coal ratio operation state where the pulverized coal ratio is 150 kg / t-pig iron or more, as shown in FIG. 6b, the central portion within the dispersion width is concentrated, and in particular, the pulverized coal ratio is 170 kg / t-pig iron or more. In the high pulverized coal ratio operation state, the central part of the pulverized coal flow is remarkably concentrated. Since oxygen is blown from the outer pipe of the double-pipe lance, the pulverized coal concentrated in the center of the pulverized coal flow does not come into contact with oxygen, but is brought into the furnace unburned to ventilate the blast furnace. make worse. Even if the amount of oxygen injection is increased to promote contact with oxygen, as shown in FIG. 6c, when the amount of oxygen injection exceeds a certain amount, pulverized coal is further increased in the center of the surrounding oxygen flow. Only the flow is concentrated, contact with oxygen is not substantially promoted, and the combustion temperature is saturated as described below.

図7は、本実施形態の二重管ランス4の吹込み先端部の詳細を示すものであり、図7aは縦断面図、図7bは図7aのA−A断面図である。そこで、本実施形態では、図7に示すように、二重管ランス4の内側管21の吹込み先端部に切欠き23を設け、この切欠き23を通じて微粉炭6と支燃性ガスである酸素9とが互いに拡散し、これにより両者が効率的に接触する状態を作り出し、もって燃焼温度を向上する。切欠き23は、例えば内側管21の内径がφ16mm程度である場合に、5mm×5mm程度の方形断面とし、これを内側管21の周方向に90度毎の等間隔に4つ設けた。外側管22はストレート管のままとした。なお、切欠き23の形状は前記に限定されるものではなく、後述するように、例えば三角形状、U字形状などであってもよく、また、切欠き23の個数も前記に限定されるものではない。   FIG. 7 shows the details of the blowing tip of the double tube lance 4 of this embodiment, FIG. 7a is a longitudinal sectional view, and FIG. 7b is an AA sectional view of FIG. 7a. Therefore, in the present embodiment, as shown in FIG. 7, a notch 23 is provided at the blowing tip of the inner pipe 21 of the double pipe lance 4, and the pulverized coal 6 and the combustion-supporting gas are provided through the notch 23. Oxygen 9 diffuses with each other, thereby creating a state of efficient contact between the two, thereby increasing the combustion temperature. For example, when the inner tube 21 has an inner diameter of about φ16 mm, the notches 23 have a rectangular cross section of about 5 mm × 5 mm, and four are provided at equal intervals of 90 degrees in the circumferential direction of the inner tube 21. The outer tube 22 was a straight tube. Note that the shape of the notch 23 is not limited to the above, but may be, for example, a triangular shape or a U-shape as described later, and the number of the notches 23 is also limited to the above. is not.

このように二重管ランス4の内側管21の吹込み先端部に切欠き23を設けると、図8aに示すように、この切欠き23を通じて微粉炭6と支燃性ガスである酸素9とが互いに拡散して接触し、燃焼温度を高めることができる。これに対し、内側管21の吹込み先端部に切欠きがない、従来の二重管ランス4では、図8bに示すように、微粉炭6が支燃性ガスである酸素9の中央部にのみ濃化してしまい、酸素9との接触量が低下して燃焼温度が飽和する。なお、前述したように、二重管ランス4の内側管21に切欠き23を設ける場合には、邪魔板などの突起物を突設する場合と異なり、突起物に微粉炭が衝突して突起物が損耗するなどのトラブルがない。   When the notch 23 is provided at the blowing tip of the inner tube 21 of the double-pipe lance 4 in this way, as shown in FIG. 8a, the pulverized coal 6 and the oxygen 9 as the combustion-supporting gas are passed through the notch 23. Can diffuse and contact each other to increase the combustion temperature. On the other hand, in the conventional double pipe lance 4 in which there is no notch at the blowing tip of the inner pipe 21, as shown in FIG. 8b, the pulverized coal 6 is in the central part of the oxygen 9 which is a combustion-supporting gas. As a result, the amount of contact with oxygen 9 decreases and the combustion temperature is saturated. As described above, when the notch 23 is provided in the inner tube 21 of the double-pipe lance 4, unlike the case where a projection such as a baffle is projected, the pulverized coal collides with the projection and the projection. There is no trouble such as wear.

図9には、微粉炭比150kg/t−銑鉄、微粉炭の揮発分25mass%以下、送風条件一定、酸素富化率一定で、内側管21の吹込み先端部に切欠き23を設けた二重管ランス4を用いた場合と、内側管21の吹込み先端部に切欠きのない二重管ランス4を用いた場合の燃焼温度を燃焼率で表した。何れも、二重管ランス4の内側管から微粉炭を吹込み、外側管から支燃性ガスとして酸素を吹込んだ。同図から明らかなように、内側管21に切欠きのない二重管ランス4を用いた場合には、ランス中の微粉炭を搬送する搬送ガスと支燃性ガスとからなるガスの酸素濃度が35vol%以上で燃焼温度が飽和してしまう。つまり、内側管21に切欠きのない二重管ランス4の場合には、酸素濃度を35vol%以上にしても燃焼温度は高くならない。これに対し、内側管21に切欠き23を設けた二重管ランス4を用いる場合には、搬送ガスと支燃性ガスとからなるガスの酸素濃度が35vol%以上でも燃焼温度が高くなる。これは、微粉炭比150kg/t−銑鉄以上170kg/t−銑鉄未満の領域では、二重管ランス4から吹込まれる微粉炭流が濃化していないことを意味する。   FIG. 9 shows a pulverized coal ratio of 150 kg / t-pig iron, a volatile content of pulverized coal of 25 mass% or less, a constant blowing condition, a constant oxygen enrichment rate, and a notch 23 provided in the blowing tip of the inner pipe 21. The combustion temperature in the case of using the heavy pipe lance 4 and the case of using the double pipe lance 4 having no notch at the blowing tip of the inner pipe 21 is represented by a combustion rate. In either case, pulverized coal was blown from the inner pipe of the double pipe lance 4, and oxygen was blown from the outer pipe as a combustion-supporting gas. As is apparent from the figure, when the double pipe lance 4 without notches is used in the inner pipe 21, the oxygen concentration of the gas composed of the carrier gas for conveying the pulverized coal in the lance and the combustion-supporting gas. Is over 35 vol%, the combustion temperature will be saturated. That is, in the case of the double pipe lance 4 in which the inner pipe 21 is not cut, the combustion temperature does not increase even if the oxygen concentration is 35 vol% or more. On the other hand, when the double pipe lance 4 provided with the notch 23 in the inner pipe 21 is used, the combustion temperature becomes high even if the oxygen concentration of the gas composed of the carrier gas and the combustion-supporting gas is 35 vol% or more. This means that the pulverized coal flow blown from the double pipe lance 4 is not concentrated in the region where the pulverized coal ratio is 150 kg / t-pig iron or more and less than 170 kg / t-pig iron.

しかし、一方、内側管21に切欠き23を設けた二重管ランス4を用いた場合でも、微粉炭比が170kg/t−銑鉄以上である場合には、図10に示すように、ランス中の搬送ガスと支燃性ガスとからなるガスの酸素濃度が70vol%以上となると、燃焼温度が飽和してしまい、それ以上、酸素濃度を高めても燃焼温度は高くならない。つまり、微粉炭比170kg/t−銑鉄以上の領域では、ランス中の搬送ガスと支燃性ガスとからなるガスの酸素濃度が70vol%以上で酸素原単位が増加するだけで、燃焼効率はよくならない。従って、内側管21に切欠き23を設けた二重管ランス4を用いる場合でも、微粉炭比を150kg/t−銑鉄以上170kg/t−銑鉄未満とするか、又は微粉炭比が170kg/t−銑鉄である場合には搬送ガスと支燃性ガスとからなるガスの酸素濃度を35vol%以上70vol%未満、好ましくは40vol%以上65vol%以下、より好ましくは45vol%以上60vol%以下とする。なお、微粉炭比の上限は300kg/t−銑鉄以下、好ましくは250kg/t−銑鉄以下とする。   However, on the other hand, even when the double pipe lance 4 provided with the notch 23 in the inner pipe 21 is used, if the pulverized coal ratio is 170 kg / t-pig iron or more, as shown in FIG. When the oxygen concentration of the gas composed of the carrier gas and the combustion-supporting gas is 70 vol% or more, the combustion temperature is saturated, and even if the oxygen concentration is increased further, the combustion temperature does not increase. In other words, in the region where the pulverized coal ratio is 170 kg / t-pig iron or more, the combustion efficiency is good only by increasing the oxygen consumption rate when the oxygen concentration of the carrier gas and the combustion-supporting gas in the lance is 70 vol% or more. Don't be. Therefore, even when using the double pipe lance 4 provided with the notch 23 in the inner pipe 21, the pulverized coal ratio is 150 kg / t-pig iron or more and less than 170 kg / t-pig iron, or the pulverized coal ratio is 170 kg / t. -In the case of pig iron, the oxygen concentration of the gas composed of the carrier gas and the combustion-supporting gas is 35 vol% or more and less than 70 vol%, preferably 40 vol% or more and 65 vol% or less, more preferably 45 vol% or more and 60 vol% or less. The upper limit of the pulverized coal ratio is 300 kg / t-pig iron or less, preferably 250 kg / t-pig iron or less.

また、内側管21の径方向から見たときの切欠き23の形状は、図11aに示すような四角形、図11bに示すような三角形、図11cに示すようなU字形などとし、切欠きの大きさは、単純に切欠き21の開口の幅と、切欠き21の開口から底までの深さで表す。また、切欠き23の先端中心と下端中心のなす角度θ、具体的には切欠き23の開口の中心と底の中心を結ぶ線分が当該開口を結ぶ弦となす角度θは、図12に示すように、30〜90°とするのが好ましい。この切欠きの形状、特に大きさを種々に変更したときの酸素と微粉炭の接触面積や微粉炭の分散幅について実験した。実験は、図13に示すように、二重管ランスの内側管及び外側管、つまり微粉炭流路及び酸素流路から夫々煙を流し、微粉炭流路から出た煙と酸素流路から出た煙の重なる領域の面積を酸素と微粉炭の接触面積として画像解析によって算出すると共に、微粉炭流路から出た煙の広がり角度から微粉炭の分散幅を求めた。実験は、内側管の径方向から見たときの切欠きの形状が四角形のものについて主として行った。   The shape of the notch 23 when viewed from the radial direction of the inner tube 21 is a quadrangle as shown in FIG. 11a, a triangle as shown in FIG. 11b, a U-shape as shown in FIG. The size is simply expressed by the width of the opening of the notch 21 and the depth from the opening of the notch 21 to the bottom. Further, the angle θ formed by the center of the notch 23 and the center of the lower end, specifically, the angle θ formed by the line connecting the center of the opening and the center of the bottom of the notch 23 and the string connecting the opening is shown in FIG. As shown, it is preferably 30 to 90 °. Experiments were conducted on the contact area between oxygen and pulverized coal and the dispersion width of pulverized coal when the shape of the notch, particularly the size, was changed in various ways. As shown in FIG. 13, the experiment was conducted by letting smoke flow from the inner and outer pipes of the double-pipe lance, that is, the pulverized coal flow path and the oxygen flow path, respectively. The area where the smoke overlapped was calculated by image analysis as the contact area of oxygen and pulverized coal, and the dispersion width of the pulverized coal was determined from the spread angle of the smoke emitted from the pulverized coal flow path. The experiment was mainly performed on a rectangular cutout when viewed from the radial direction of the inner tube.

まず、切欠きの幅を種々に変更したときの酸素と微粉炭の接触面積及び微粉炭の分散幅を図14に示す。切欠きの幅は、内側管の内周の長さに対する全ての切欠きの幅の計の比で表し、酸素と微粉炭の接触面積及び微粉炭の分散幅は、切欠きのない内側管を用いたときの比率で表した。図から明らかなように、切欠きの幅を大きくすると、酸素と微粉炭の接触面積も微粉炭の分散幅も大きくなるが、微粉炭の分散幅はあるところから減少傾向となる。これは、切欠きの幅を大きくすると、酸素と微粉炭の混合性はよくなるものの、切欠きの幅が大きすぎると、酸素が二重管ランスの径方向内側に流れ込んで微粉炭の分散が抑えられるためであると考えられる。そのため、切欠きの幅は、内側管外周に対する全ての切欠きの幅の計の比で0を超え、0.5以下とするのが好ましく、より好ましくは0.05以上、0.3以下とし、更に好ましくは0.1以上、0.2以下とする。   First, FIG. 14 shows the contact area between oxygen and pulverized coal and the dispersion width of pulverized coal when the width of the notch is variously changed. The width of the notch is expressed as the ratio of the total width of all the notches to the inner circumference of the inner pipe.The contact area of oxygen and pulverized coal and the dispersion width of the pulverized coal are the same for the inner pipe without notches. Expressed as a ratio when used. As is apparent from the figure, when the width of the notch is increased, the contact area between oxygen and pulverized coal and the dispersion width of pulverized coal increase, but the dispersion width of pulverized coal tends to decrease from a certain point. This is because, when the width of the notch is increased, the mixing of oxygen and pulverized coal improves, but when the width of the notch is too large, oxygen flows into the radial inner side of the double-pipe lance and suppresses the dispersion of pulverized coal. It is thought that this is because Therefore, the width of the notch is preferably more than 0 and not more than 0.5, more preferably not less than 0.05 and not more than 0.3, as a ratio of the total width of all notches to the outer circumference of the inner tube. More preferably, it is 0.1 or more and 0.2 or less.

また、切欠きの深さを種々に変更したときの酸素と微粉炭の接触面積及び微粉炭の分散幅を図15に示す。切欠きの深さは深さそのものの寸法で表し、酸素と微粉炭の接触面積及び微粉炭の分散幅は、切欠きのない内側管を用いたときの比率で表した。図から明らかなように、切欠きの深さを大きくすると、酸素と微粉炭の接触面積も微粉炭の分散幅も大きくなるが、微粉炭の分散幅はあるところから減少傾向となる。これは、切欠きの深さを大きくすると、酸素と微粉炭の混合性はよくなるものの、切欠きの深さが大きすぎると、ランス先端での流れが安定化するため、微粉炭の分散が抑えられるためであると考えられる。そのため、切欠きの深さは、寸法で0を超え、12mm以下とするのが好ましく、より好ましくは2mm以上、10mm以下とし、更に好ましくは3mm以上、7mm以下とする。   FIG. 15 shows the contact area between oxygen and pulverized coal and the dispersion width of pulverized coal when the depth of the notch is variously changed. The depth of the notch is represented by the dimension of the depth itself, and the contact area between oxygen and pulverized coal and the dispersion width of the pulverized coal are represented by the ratio when an inner pipe without a notch is used. As is clear from the figure, when the depth of the notch is increased, the contact area between oxygen and pulverized coal and the dispersion width of pulverized coal increase, but the dispersion width of pulverized coal tends to decrease from a certain point. This is because if the depth of the notch is increased, the mixing of oxygen and pulverized coal will be improved, but if the depth of the notch is too large, the flow at the tip of the lance will be stabilized, and dispersion of pulverized coal will be suppressed. It is thought that this is because Therefore, the depth of the notch exceeds 0 in dimension and is preferably 12 mm or less, more preferably 2 mm or more and 10 mm or less, and further preferably 3 mm or more and 7 mm or less.

また、切欠きの数を種々に変更したときの酸素と微粉炭の接触面積及び微粉炭の分散幅を図16に示す。切欠きの数は最大切欠き数に対する切欠き数の比で表し、酸素と微粉炭の接触面積及び微粉炭の分散幅は、切欠きのない内側管を用いたときの比率で表した。なお、最大切欠き数とは、内側管の内周長を切欠きの幅で除したときの整数部であり、具体的には内側管に所定幅の切欠きを最大で幾つ形成できるかを表すものである。図から明らかなように、切欠きの数を多くすると、酸素と微粉炭の接触面積も微粉炭の分散幅も大きくなるが、微粉炭の分散幅はあるところから減少傾向となる。これは、切欠きの数を多くすると、酸素と微粉炭の混合性や微粉炭の分散性はよくなるものの、切欠きの数が多すぎると、内側管に流れる酸素の比率が大きくなり、微粉炭の分散が抑えられるためであると考えられる。そのため、切欠きの数は、最大切欠き数に対する切欠き数の比で0を超え、0.8以下とするのが好ましく、より好ましくは0.1以上、0.6以下とし、更に好ましくは0.2以上、0.5以下とする。   FIG. 16 shows the contact area between oxygen and pulverized coal and the dispersion width of pulverized coal when the number of notches is variously changed. The number of notches was represented by the ratio of the number of notches to the maximum number of notches, and the contact area between oxygen and pulverized coal and the dispersion width of pulverized coal were represented by the ratio when an inner pipe without notches was used. The maximum number of notches is an integer part obtained by dividing the inner peripheral length of the inner tube by the width of the notch, and specifically, how many notches of a predetermined width can be formed at the maximum in the inner tube. It represents. As is clear from the figure, when the number of notches is increased, the contact area between oxygen and pulverized coal and the dispersion width of pulverized coal increase, but the dispersion width of pulverized coal tends to decrease from a certain point. This is because if the number of notches is increased, the mixing of oxygen and pulverized coal and the dispersibility of pulverized coal will be improved, but if the number of notches is too large, the proportion of oxygen flowing into the inner pipe will increase and the pulverized coal will increase. This is thought to be due to the suppression of dispersion. Therefore, the number of notches is preferably more than 0 and not more than 0.8 in the ratio of the number of notches to the maximum number of notches, more preferably not less than 0.1 and not more than 0.6, still more preferably. It shall be 0.2 or more and 0.5 or less.

また、切欠きの形状が四角形である場合と三角形である場合で、それらの切欠きの幅を種々に変更したときの酸素と微粉炭の接触面積及び微粉炭の分散幅を図17に示す。図17は、前述した図14に、三角形の切欠きの実験結果を上書きしたものである。切欠きの幅は、内側管の内周の長さに対する全ての切欠きの幅の計の比で表し、酸素と微粉炭の接触面積及び微粉炭の分散幅は、切欠きのない内側管を用いたときの比率で表した。図から明らかなように、切欠きの形状が四角形である場合も三角形である場合も、切欠きの幅を大きくすると、酸素と微粉炭の接触面積も微粉炭の分散幅も大きくなるが、微粉炭の分散幅はあるところから減少傾向となる。この理由は、切欠きの形状が三角形である場合も、前記図14の説明と同様に、切欠きの幅を大きくすると、酸素と微粉炭の混合性はよくなるものの、切欠きの幅が大きすぎると、酸素が二重管ランスの径方向内側に流れ込んで微粉炭の分散が抑えられるためであると考えられる。そのため、切欠きの幅は、切欠きの形状そのものにかかわらず、内側管外周に対する全ての切欠きの幅の計の比で0を超え、0.5以下とするのが好ましく、より好ましくは0.05以上、0.3以下とし、更に好ましくは0.1以上、0.2以下とする。   FIG. 17 shows the contact area between oxygen and pulverized coal and the dispersion width of pulverized coal when the notch shape is a square and a triangle, and the widths of the notches are variously changed. FIG. 17 is obtained by overwriting the above-described FIG. 14 with the experimental result of the triangular notch. The width of the notch is expressed as the ratio of the total width of all the notches to the inner circumference of the inner pipe.The contact area of oxygen and pulverized coal and the dispersion width of the pulverized coal are the same for the inner pipe without notches. Expressed as a ratio when used. As is clear from the figure, whether the shape of the notch is square or triangular, increasing the width of the notch increases the contact area between oxygen and pulverized coal and the dispersion width of pulverized coal. The distribution width of charcoal tends to decrease. The reason for this is that even when the shape of the notch is a triangle, if the width of the notch is increased, the mixing of oxygen and pulverized coal is improved, but the width of the notch is too large. This is considered to be because oxygen flows into the radial inner side of the double-pipe lance and dispersion of pulverized coal is suppressed. Therefore, the width of the notch is preferably greater than 0 and less than or equal to 0.5, more preferably 0, as a ratio of the total width of all the notches with respect to the outer periphery of the inner pipe, regardless of the shape of the notch itself. .05 or more and 0.3 or less, more preferably 0.1 or more and 0.2 or less.

ところで、前述のような燃焼温度の上昇に伴って、二重管ランスの外側管は高温に晒され易くなる。ランスは、例えばステンレス鋼鋼管で構成される。ランスの外側には所謂ウォータージャケットと呼ばれる水冷が施されている例もあるが、ランス先端までは覆うことができない。特に、この水冷の及ばない二重管ランスの外側管の先端部が熱で変形し易いことが分かった。ランスが変形する、つまり曲がると所望部位にガスや微粉炭を吹込むことができないし、消耗品であるランスの交換作業に支障がある。また、微粉炭の流れが変化して羽口に当たることも考えられ、そのような場合には羽口が損傷する恐れがある。また、二重管ランスの外側管が曲がると、内側管との隙間が閉塞され、外側管からガスが流れなくなると、二重管ランスの外側管が溶損し、場合によっては送風管が破損する可能性もある。ランスが変形したり損耗したりすると、前述のような燃焼温度を確保することができなくなり、ひいては還元材原単位を低減することもできない。   By the way, as the combustion temperature rises as described above, the outer tube of the double tube lance is easily exposed to high temperature. The lance is composed of, for example, a stainless steel pipe. Although there is an example where water cooling called a so-called water jacket is performed outside the lance, the tip of the lance cannot be covered. In particular, it has been found that the tip of the outer tube of the double tube lance that is not subject to water cooling is easily deformed by heat. If the lance is deformed, that is, bent, gas or pulverized coal cannot be blown into a desired part, and there is a problem in replacing the lance that is a consumable item. In addition, the flow of pulverized coal may change and hit the tuyere, and in such a case, the tuyere may be damaged. Also, if the outer pipe of the double pipe lance is bent, the gap with the inner pipe is closed, and if the gas does not flow from the outer pipe, the outer pipe of the double pipe lance is melted, and in some cases, the blower pipe is damaged. There is a possibility. If the lance is deformed or worn out, the combustion temperature as described above cannot be secured, and as a result, the reducing material basic unit cannot be reduced.

水冷できない二重管ランスの外側管を冷却するためには、内部に流れるガスで冷却するしかない。内部に流れるガスに放熱して例えば二重管ランスの外側管自体を冷却する場合、ガスの流速がランス温度に影響を与えると考えられる。そこで、本発明者等は、二重管ランスの外側管から吹込まれるガスの流速を種々に変更してランス表面の温度を測定した。実験は、二重管ランスの外側管から酸素を吹込み、内側管から微粉炭を吹込んで行い、ガスの流速調整は、外側管から吹込まれる酸素の供給量を加減した。なお、酸素は、酸素富化空気でもよく、2%以上、好ましくは10%以上の酸素富化空気を使用する。酸素富化空気を使用することによって、冷却の他、微粉炭の燃焼性の向上を図る。測定結果を図18に示す。   The only way to cool the outer tube of a double-pipe lance that cannot be cooled with water is by cooling with the gas flowing inside. When heat is radiated to the gas flowing inside to cool the outer tube itself of the double tube lance, for example, the gas flow rate is considered to affect the lance temperature. Therefore, the inventors measured the temperature of the lance surface by variously changing the flow rate of the gas blown from the outer pipe of the double pipe lance. The experiment was performed by blowing oxygen from the outer pipe of the double pipe lance and blowing pulverized coal from the inner pipe, and the gas flow rate was adjusted by adjusting the amount of oxygen supplied from the outer pipe. The oxygen may be oxygen-enriched air, and 2% or more, preferably 10% or more of oxygen-enriched air is used. By using oxygen-enriched air, flammability of pulverized coal is improved in addition to cooling. The measurement results are shown in FIG.

二重管ランスの外側管には、20Aスケジュール5Sと呼ばれる鋼管を用いた。また、二重管ランスの内側管には、15Aスケジュール90と呼ばれる鋼管を用い、外側管から吹込まれる酸素と窒素の合計流速を種々に変更してランス表面の温度を測定した。ちなみに、「15A」、「20A」はJIS G 3459に規定する鋼管外径の称呼寸法であり、15Aは外径21.7mm、20Aは外径27.2mmである。また、「スケジュール」はJIS G 3459に規定する鋼管の肉厚の称呼寸法であり、20Aスケジュール5Sは1.65mm、15Aスケジュール90は3.70mmである。なお、ステンレス鋼鋼管の他、普通鋼も利用できる。その場合の鋼管の外径はJIS G 3452に規定され、肉厚はJIS G 3454に規定される。   A steel pipe called 20A schedule 5S was used for the outer pipe of the double pipe lance. In addition, a steel pipe called 15A schedule 90 was used as the inner pipe of the double pipe lance, and the total flow rate of oxygen and nitrogen blown from the outer pipe was variously changed to measure the temperature of the lance surface. Incidentally, “15A” and “20A” are nominal dimensions of the steel pipe outer diameter defined in JIS G 3459, 15A has an outer diameter of 21.7 mm, and 20A has an outer diameter of 27.2 mm. The “schedule” is a nominal dimension of the thickness of the steel pipe specified in JIS G 3459. The 20A schedule 5S is 1.65 mm, and the 15A schedule 90 is 3.70 mm. In addition to stainless steel pipes, plain steel can also be used. In this case, the outer diameter of the steel pipe is specified in JIS G 3453, and the wall thickness is specified in JIS G 3454.

同図に二点鎖線で示すように、二重管ランスの外側管から吹込まれるガスの流速の増加に伴ってランス表面の温度が反比例的に低下している。鋼管を二重管ランスに使用する場合、二重管ランスの表面温度が880℃を上回るとクリープ変形が起こり、二重管ランスが曲がってしまう。従って、二重管ランスの外側管に20Aスケジュール5Sの鋼管を用い、二重管ランスの表面温度が880℃以下である場合の二重管ランスの外側管の出口流速は20m/sec以上となる。そして、二重管ランスの外側管の出口流速が20m/sec以上である場合には二重管ランスに変形や曲がりは生じない。一方、二重管ランスの外側管の出口流速が120m/secを超えたりすると、設備の運用コストの点で実用的でないので、二重管ランスの外側管の出口流速の上限を120m/secとした。ちなみに、単管ランスは二重管ランスに比べて熱負荷が少ないため、必要に応じ、出口流速を20m/sec以上とすればよい。   As indicated by a two-dot chain line in the figure, the temperature of the lance surface decreases inversely with the increase in the flow velocity of the gas blown from the outer pipe of the double pipe lance. When using a steel pipe for a double pipe lance, when the surface temperature of a double pipe lance exceeds 880 degreeC, creep deformation will occur and a double pipe lance will bend. Therefore, when the steel pipe of 20A schedule 5S is used for the outer pipe of the double pipe lance and the surface temperature of the double pipe lance is 880 ° C. or less, the outlet flow velocity of the outer pipe of the double pipe lance is 20 m / sec or more. . And when the exit flow velocity of the outer pipe of the double pipe lance is 20 m / sec or more, the double pipe lance is not deformed or bent. On the other hand, if the outlet flow velocity of the outer pipe of the double pipe lance exceeds 120 m / sec, it is not practical in terms of the operating cost of the equipment, so the upper limit of the outlet flow velocity of the outer pipe of the double pipe lance is 120 m / sec. did. Incidentally, since the single tube lance has a smaller thermal load than the double tube lance, the outlet flow velocity may be set to 20 m / sec or more as necessary.

前記実施形態では、微粉炭の平均粒子径は10〜100μmで使用されるが、燃焼性を確保し、ランスからの送給並びにランスまでの供給性を考慮したとき、好ましくは20〜50μmとするとよい。微粉炭の平均粒子径が20μm未満では、燃焼性は優れるが、微粉炭輸送時(気体輸送)にランスが詰まり易く、50μmを超えると微粉炭燃焼性が悪化する恐れがある。   In the said embodiment, although the average particle diameter of pulverized coal is used with 10-100 micrometers, when ensuring combustibility and considering the supply property to a lance and supply to a lance, when it is preferably 20-50 micrometers Good. If the average particle size of the pulverized coal is less than 20 μm, the combustibility is excellent, but the lance is easily clogged during pulverized coal transportation (gas transportation), and if it exceeds 50 μm, the pulverized coal combustibility may be deteriorated.

また、二重管ランスの内側管から吹込む微粉炭として使用できるのは、25mass%以下の揮発分を有する石炭の他、無煙炭も固体還元材として使用してよい。無煙炭は3〜5mass%の揮発分を有する。従って、本発明では、使用する微粉炭は、無煙炭を含む、3mass%以上25mass%以下の揮発分を有する微粉炭と表現する。
また、吹込む固体還元材には、微粉炭を主として、その中に廃プラスチック、廃棄物固形燃料(RDF)、有機性資源(バイオマス)、廃材、CDQ集塵コークスを使用してもよい。CDQ集塵コークスは、乾式消火装置(CDQ)で集塵されたコークス粉である。使用の際は、微粉炭の全固体還元材に対する比は80mass%以上とするのが好ましい。即ち、微粉炭と、廃プラスチック、廃棄物固形燃料(RDF)、有機性資源(バイオマス)、廃材、CDQ集塵コークスなどでは反応による熱量が異なるため、互いの使用比率が近くなると燃焼に偏りが生じ易くなり、操業の不安定となり易い。また、微粉炭と比して、廃プラスチック、廃棄物固形燃料(RDF)、有機性資源(バイオマス)、廃材等は燃焼反応による発熱量が低位であるため、多量に吹込むと炉頂より装入される固体還元材に対する代替効率が低下するため、またCDQ集塵コークスは発熱量は高いが、揮発分がないため着火しにくく、代替効率が低下するため、微粉炭の割合を80mass%以上とするのが好ましいのである。
In addition to coal having a volatile content of 25 mass% or less, anthracite coal may be used as the solid reducing material that can be used as pulverized coal blown from the inner tube of the double tube lance. Anthracite has a volatile content of 3-5 mass%. Therefore, in this invention, the pulverized coal to be used is expressed as pulverized coal having an volatile content of 3 mass% or more and 25 mass% or less including anthracite coal.
Further, as the solid reducing material to be blown in, pulverized coal is mainly used, and waste plastic, waste solid fuel (RDF), organic resources (biomass), waste material, and CDQ dust collecting coke may be used therein. CDQ dust collection coke is coke powder collected by a dry fire extinguisher (CDQ). In use, the ratio of pulverized coal to the all-solid reducing material is preferably 80 mass% or more. In other words, pulverized coal and waste plastics, waste solid fuel (RDF), organic resources (biomass), waste materials, CDQ dust collection coke, etc. have different amounts of heat due to the reaction. It tends to occur and the operation becomes unstable. Compared with pulverized coal, waste plastics, solid waste fuel (RDF), organic resources (biomass), waste materials, etc. have a lower calorific value due to the combustion reaction. Since the substitution efficiency for the solid reducing material is reduced, and the CDQ dust collection coke has a high calorific value, it is difficult to ignite because there is no volatile matter, and the substitution efficiency is reduced, so the proportion of pulverized coal is 80 mass% or more It is preferable that

なお、廃プラスチック、廃棄物固形燃料(RDF)、有機性資源(バイオマス)、廃材は、6mm以下、好ましくは3mm以下の細粒として微粉炭と使用できる。また、CDQ集塵コークスはそのまま使用可能である。微粉炭との割合は、搬送ガスにより気送される微粉炭と合流させることで混合可能である。予め微粉炭と混合して使用しても構わない。
このように、本実施形態の高炉操業方法では、羽口3から燃料を吹込むためのランス4を二重管とし、二重管ランス4の内側管21から微粉炭を吹込むと共に、二重管ランス4の外側管22から酸素(支燃性ガス)を吹込み、二重管ランス4の内側管21の吹込み先端部に切欠き23を設け、微粉炭を搬送する搬送ガスと支燃性ガスとからなるガスの酸素濃度を35vol%以上とすることにより、微粉炭の揮発分が25mass%以下で且つ微粉炭比が150kg/t−銑鉄以上の高微粉炭比操業であっても燃焼温度を高めることができ、その結果、排出CO2を低減することができる。また、微粉炭比が170kg/t−銑鉄以上の場合には、微粉炭を搬送する搬送ガスと支燃性ガスとからなるガスの酸素濃度を70vol%未満とすることにより、酸素原単位を抑制することができる。
Waste plastics, solid waste fuel (RDF), organic resources (biomass), and waste materials can be used with pulverized coal as fine particles of 6 mm or less, preferably 3 mm or less. The CDQ dust collecting coke can be used as it is. The ratio with pulverized coal can be mixed by merging with pulverized coal fed by carrier gas. You may mix and use beforehand with pulverized coal.
Thus, in the blast furnace operating method of the present embodiment, the lance 4 for injecting fuel from the tuyere 3 is a double pipe, pulverized coal is injected from the inner pipe 21 of the double pipe lance 4, and the double pipe lance is used. 4, oxygen (flammable gas) is blown from the outer pipe 22, a notch 23 is provided at the blowing tip of the inner pipe 21 of the double pipe lance 4, and a carrier gas and a flammable gas for conveying pulverized coal. By setting the oxygen concentration of the gas consisting of 35 vol% or more to a high pulverized coal ratio operation in which the volatile content of pulverized coal is 25 mass% or less and the pulverized coal ratio is 150 kg / t-pig iron or more As a result, emission CO 2 can be reduced. In addition, when the pulverized coal ratio is 170 kg / t-pig iron or more, the oxygen concentration is suppressed by setting the oxygen concentration of the gas composed of the carrier gas for conveying the pulverized coal and the combustion-supporting gas to less than 70 vol%. can do.

また、切欠き23を二重管ランス4の内側管21の先端部周方向に等間隔に複数設けることにより、微粉炭及び支燃性ガスの拡散を促進し、燃焼効率をより一層向上することができる。
また、送風に富化する酸素の一部を(支燃性ガスとして)二重管ランス4の外側管22から吹込むことにより、高炉内のガスバランスを損なうことがなく、酸素の過剰供給を回避することができると共に、使用する酸素の原単位を低減することができる。
Further, by providing a plurality of notches 23 at equal intervals in the circumferential direction of the distal end of the inner pipe 21 of the double pipe lance 4, the diffusion of pulverized coal and combustion-supporting gas is promoted, and the combustion efficiency is further improved. Can do.
In addition, by blowing a part of oxygen enriched in blowing air (as a combustion-supporting gas) from the outer tube 22 of the double tube lance 4, the oxygen balance can be excessively supplied without impairing the gas balance in the blast furnace. This can be avoided and the basic unit of oxygen used can be reduced.

1は高炉
2は送風管
3は羽口
4はランス
5はレースウエイ
6は微粉炭
7はコークス
8はチャー
9は酸素
21は内側管
22は外側管
23は切欠き
1 is a blast furnace 2 is a blower tube 3 is a tuyere 4 is a lance 5 is a raceway 6 is pulverized coal 7 is coke 8 is char 9 is oxygen 21 is an inner tube 22 is an outer tube 23 is notched

Claims (28)

揮発分が25mass%以下の微粉炭を準備し、
羽口から微粉炭と支燃性ガスを吹込むための、内側管と外側管とを有する二重管ランスを準備し、
前記羽口から熱風を吹込み、
前記二重管ランスの内側管の吹込み先端部に、軸方向に凹んだ切欠きを周方向に複数設け、
当該内側管から150kg/t−銑鉄以上の微粉炭比で前記微粉炭を搬送ガスと共に吹込み、
前記二重管ランスの外側管から支燃性ガスを吹込み、
前記搬送ガスと支燃性ガスとからなるガスの酸素濃度が35vol%以上である、
高炉操業方法。
Prepare pulverized coal with a volatile content of 25 mass% or less,
Preparing a double pipe lance with an inner pipe and an outer pipe for injecting pulverized coal and supporting gas from the tuyere,
Hot air is blown from the tuyere,
A plurality of notches recessed in the axial direction are provided in the circumferential direction in the blowing tip of the inner tube of the double tube lance,
Blowing the pulverized coal with a carrier gas at a pulverized coal ratio of 150 kg / t-pig iron or more from the inner pipe,
Blowing inflammable gas from the outer pipe of the double pipe lance,
The oxygen concentration of the gas composed of the carrier gas and the combustion-supporting gas is 35 vol% or more,
Blast furnace operation method.
前記切欠きは、前記二重管ランスの内側管の先端部周方向に等間隔に設けられている請求項1に記載の高炉操業方法。   The blast furnace operating method according to claim 1, wherein the notches are provided at equal intervals in the circumferential direction of the tip of the inner tube of the double tube lance. 前記切欠きの幅は、前記二重管ランスの内側管の内周の長さに対する全ての切欠きの幅の計の比で0を超え、0.5以下とする請求項2に記載の高炉操業方法。   The blast furnace according to claim 2, wherein the width of the notch is greater than 0 and less than or equal to 0.5 in the ratio of the total width of all the notches to the inner circumference of the inner tube of the double pipe lance. Operation method. 前記切欠きの幅は、前記二重管ランスの内側管の内周の長さに対する全ての切欠きの幅の計の比で0.05以上、0.3以下とする請求項3に記載の高炉操業方法。   The width of the notch is 0.05 or more and 0.3 or less as a ratio of the total width of all the notches to the inner peripheral length of the inner pipe of the double pipe lance. Blast furnace operation method. 前記切欠きの幅は、前記二重管ランスの内側管の内周の長さに対する全ての切欠きの幅の計の比で0.1以上、0.2以下とする請求項4に記載の高炉操業方法。   The width of the notch is 0.1 or more and 0.2 or less as a ratio of the total width of all the notches to the inner circumference of the inner pipe of the double pipe lance. Blast furnace operation method. 前記切欠きの深さは、0mmを超え、12mm以下とする請求項2に記載の高炉操業方法。   The blast furnace operating method according to claim 2, wherein the depth of the notch is greater than 0 mm and not greater than 12 mm. 前記切欠きの深さは、2mm以上、10mm以下とする請求項6に記載の高炉操業方法。   The blast furnace operating method according to claim 6, wherein a depth of the notch is 2 mm or more and 10 mm or less. 前記切欠きの深さは、3mm以上、7mm以下とする請求項7に記載の高炉操業方法。   The blast furnace operating method according to claim 7, wherein a depth of the notch is 3 mm or more and 7 mm or less. 前記二重管ランスの内側管の内周長を1つの切欠きの幅で除したときの整数部を最大切欠き数とした場合、前記切欠きの数は、最大切欠き数に対する切欠き数の比で0を超え、0.8以下とする請求項2に記載の高炉操業方法。   When the integral part when the inner peripheral length of the inner tube of the double pipe lance is divided by the width of one notch is the maximum number of notches, the number of notches is the number of notches with respect to the maximum number of notches. The blast furnace operating method according to claim 2, wherein the ratio is more than 0 and 0.8 or less. 前記切欠きの数は、前記最大切欠き数に対する切欠き数の比で0.1以上、0.6以下とする請求項9に記載の高炉操業方法。   The blast furnace operating method according to claim 9, wherein the number of notches is 0.1 to 0.6 in terms of a ratio of the number of notches to the maximum number of notches. 前記切欠きの数は、前記最大切欠き数に対する切欠き数の比で0.2以上、0.5以下とする請求項10に記載の高炉操業方法。   The blast furnace operating method according to claim 10, wherein the number of notches is 0.2 to 0.5 in terms of the ratio of the number of notches to the maximum number of notches. 前記支燃性ガスは酸素であり、送風に富化する酸素の一部を前記二重管ランスの外側管から吹込む請求項1に記載の高炉操業方法。   The blast furnace operating method according to claim 1, wherein the combustion-supporting gas is oxygen, and a part of oxygen enriched in blowing is blown from an outer pipe of the double pipe lance. 前記微粉炭が、3mass%以上25mass%以下の揮発分を有する請求項1に記載の高炉操業方法。   The blast furnace operating method according to claim 1, wherein the pulverized coal has a volatile content of 3 mass% or more and 25 mass% or less. 前記二重管ランスの外側管から吹込まれる支燃性ガスが、20〜120m/secの出口流速を有する請求項1に記載の高炉操業方法。   The blast furnace operating method according to claim 1, wherein the combustion-supporting gas blown from the outer pipe of the double pipe lance has an outlet flow velocity of 20 to 120 m / sec. 前記微粉炭比が170kg/t−銑鉄以上である請求項1に記載の高炉操業方法。   The blast furnace operating method according to claim 1, wherein the pulverized coal ratio is 170 kg / t-pig iron or more. 前記微粉炭比が170kg/t−銑鉄以上であり、
前記搬送ガスと支燃性ガスとからなるガスの酸素濃度が35vol%以上70vol%未満である、
請求項1に記載の高炉操業方法。
The pulverized coal ratio is 170 kg / t-pig iron or more,
The oxygen concentration of the gas consisting of the carrier gas and the combustion-supporting gas is 35 vol% or more and less than 70 vol%,
The blast furnace operating method according to claim 1.
前記搬送ガスと支燃性ガスとからなるガスの酸素濃度が40vol%以上65vol%以下である請求項16に記載の高炉操業方法。   The blast furnace operating method according to claim 16, wherein the oxygen concentration of the gas composed of the carrier gas and the combustion-supporting gas is 40 vol% or more and 65 vol% or less. 前記搬送ガスと支燃性ガスとからなるガスの酸素濃度が45vol%以上60vol%以下である請求項17に記載の高炉操業方法。   The blast furnace operating method according to claim 17, wherein the oxygen concentration of the gas composed of the carrier gas and the combustion-supporting gas is 45 vol% or more and 60 vol% or less. 前記微粉炭比が170kg/t−銑鉄以上300kg/t−銑鉄以下である請求項15に記載の高炉操業方法。   The blast furnace operating method according to claim 15, wherein the pulverized coal ratio is 170 kg / t-pig iron or more and 300 kg / t-pig iron or less. 前記微粉炭比が170kg/t−銑鉄以上300kg/t−銑鉄以下である請求項16に記載の高炉操業方法。   The blast furnace operating method according to claim 16, wherein the pulverized coal ratio is 170 kg / t-pig iron or more and 300 kg / t-pig iron or less. 前記搬送ガスと支燃性ガスとからなるガスの酸素濃度が35vol%以上70vol%未満である請求項1に記載の高炉操業方法。   The blast furnace operating method according to claim 1, wherein the oxygen concentration of the gas composed of the carrier gas and the combustion-supporting gas is not less than 35 vol% and less than 70 vol%. 前記搬送ガスと支燃性ガスとからなるガスの酸素濃度が40vol%以上65vol%以下である請求項21に記載の高炉操業方法。   The method for operating a blast furnace according to claim 21, wherein the oxygen concentration of the gas composed of the carrier gas and the combustion-supporting gas is 40 vol% or more and 65 vol% or less. 前記搬送ガスと支燃性ガスとからなるガスの酸素濃度が45vol%以上60vol%以下である請求項22に記載の高炉操業方法。   The blast furnace operating method according to claim 22, wherein the oxygen concentration of the gas composed of the carrier gas and the combustion-supporting gas is 45 vol% or more and 60 vol% or less. 前記微粉炭比が150kg/t−銑鉄以上300kg/t−銑鉄以下である請求項1に記載の高炉操業方法。   The blast furnace operating method according to claim 1, wherein the pulverized coal ratio is 150 kg / t-pig iron or more and 300 kg / t-pig iron or less. 前記微粉炭比が150kg/t−銑鉄以上170kg/t−銑鉄未満である請求項1に記載の高炉操業方法。   The blast furnace operating method according to claim 1, wherein the pulverized coal ratio is 150 kg / t-pig iron or more and less than 170 kg / t-pig iron. 前記微粉炭比が150kg/t−銑鉄以上170kg/t−銑鉄未満であり、
前記搬送ガスと支燃性ガスとからなるガスの酸素濃度が35vol以上70vol%未満である、
請求項1に記載の高炉操業方法。
The pulverized coal ratio is 150 kg / t-pig iron or more and less than 170 kg / t-pig iron,
The oxygen concentration of the gas composed of the carrier gas and the combustion-supporting gas is 35 vol. Or more and less than 70 vol.%.
The blast furnace operating method according to claim 1.
前記微粉炭に、廃プラスチック、廃棄物固形燃料、有機性資源、廃材、CDQ集塵コークスからなるグループのうち、少なくとも1つを加える請求項1乃至26の何れか一項に記載の高炉操業方法。   The blast furnace operating method according to any one of claims 1 to 26, wherein at least one of a group consisting of waste plastic, solid waste fuel, organic resources, waste material, and CDQ dust collection coke is added to the pulverized coal. . 前記微粉炭の割合を80mass%以上として、前記廃プラスチック、廃棄物固形燃料、有機性資源、廃材、CDQ集塵コークスを使用する請求項27に記載の高炉操業方法。   The blast furnace operating method according to claim 27, wherein the ratio of the pulverized coal is 80 mass% or more, and the waste plastic, waste solid fuel, organic resource, waste material, and CDQ dust collection coke are used.
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