JP2012017528A - Method for operating blast furnace using woody biomass as raw material, and coke production method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for effectively using woody biomass in a steel plant, that is, the methods for operating a blast furnace using woody biomass as a raw material and for producing cokes using woody biomass as the raw material, and also to achieve the reduction of a reducing material ratio in the blast furnace by using woody biomass.SOLUTION: The method for operating a blast furnace is characterized by heating and drying the woody biomass to use as a blast-furnace raw material. In that case, they are preferable to: dry the woody biomass so as to be ≥5 and <30 mass% in a moisture content; perform drying of the biomass by using the waste heat of ≤300°C; pulverize the dried biomass to obtain a molded body by molding together with a coal; and charge, in the blast furnace, the cokes produced by charging the molded body with the coal in a coke oven and drying it.

Description

The present invention relates to a technique for reducing the amount of coal used by substituting a part of coal used in the steel manufacturing process with woody biomass, and relates to the woody that can achieve energy saving and CO ₂ emission reduction according to the amount of biomass used. The present invention relates to a method for operating a blast furnace using biomass as a raw material and a method for producing coke.

Even in Japan's steel industry, where energy conservation is thorough, further energy conservation and CO ₂ emission reductions are required to achieve the greenhouse gas emission reduction targets set by the Kyoto Protocol. Since the use of biomass can be an effective means for reducing CO ₂ emissions due to carbon neutral, various methods of using biomass have been proposed in the steel industry. For example, a method of blowing pulverized waste wood powder or carbonized powder of RDF (Refused Derived Fuel) into a blast furnace together with pulverized coal, a method of mixing with coal powder and charging into a coke oven, etc. have been proposed (for example, non-patent literature) 1). In addition, an experiment of blowing carbon-neutral woody biomass into a blast furnace with the aim of reducing CO ₂ emissions has also been performed (see, for example, Non-Patent Document 2).

  As a method for producing coke using biomass, there has been proposed a method in which woody biomass chips are blended with raw coal powder, and this mixture is charged into a normal room furnace type coke oven and subjected to high temperature dry distillation. At this time, pyrolysis gas and tar are recovered as by-products, and residual carbides are used as coke. In this method, it is possible to thermally decompose woody biomass at a high temperature and recover 100% of the generated gas, tar, and residue (charcoal). However, biomass chips have large particle size differences and density differences from coal, and it is difficult to mix them uniformly into a coke oven. In addition, woody biomass does not exhibit caking properties when heated, so the bonding strength between particles is weakened, and the reactivity of coke produced after high temperature dry distillation is improved, but the strength is significantly reduced, so it can be used as blast furnace coke. There was a limit to the amount of biomass blended. Furthermore, the woody biomass has a high water content of 30 to 60 mass% and a low density. For this reason, when charging a mixture of coal and biomass into a chamber-type coke oven, there is a problem that the charging density becomes low due to the gravity charging method, and as a result, the productivity of coke decreases and during dry distillation Phenomena such as an increase in the amount of heat generated, an increase in the heat consumption of coke production, and a decrease in the efficiency of gas purification equipment were likely to occur. In order to solve these problems, as a method of using the biomass raw material in a chamber furnace type coke oven, the biomass raw material is first heat-treated at 150 to 400 ° C., and the oil component generated by thermal decomposition is separated and recovered. Next, a method is proposed in which the char of the residue is pulverized to a predetermined particle size, then supplied to a coke production facility, coal and char are mixed, charged into a coke oven, and carbonized to produce coke. (For example, refer to Patent Document 1).

  On the other hand, as a method for operating a blast furnace using biomass, there has been proposed a method for efficiently operating a blast furnace by blowing dry sewage sludge together with pulverized coal as biomass from a blast furnace tuyere (see, for example, Patent Document 2). Also, a ferro-coke manufacturing method in which woody biomass is mixed and molded with coal and iron ore and carbonized in a chamber-type coke oven, and the heat storage zone temperature of the blast furnace is lowered by using this method, thereby reducing the reducing material ratio of the blast furnace. A blast furnace operating method has been proposed (see, for example, Patent Document 3). Patent Document 3 can reduce the temperature of the blast furnace shaft portion by using coke with increased reactivity as a blast furnace raw material, and as a result, the FeO-Fe reduction equilibrium achievement is constant, leading to a reduction in the reducing material ratio. The result is similar to that of the report (for example, see Non-Patent Document 3).

Further carbonized biomass, which together reduce the use as a sintering energy by adding the sintering raw material, is proposed sinter manufacturing method of reducing NO _x, SO _x in the exhaust gas easily at low cost (For example, refer to Patent Document 4).

Japanese Patent Laying-Open No. 2005-272569 (FIG. 1) Japanese Patent Laid-Open No. 2006-37196 (FIGS. 1 and 2) JP 2004-217914 A (Table 1, FIG. 4) JP 2003-328044 A (FIG. 1)

Yoshio Okuno "Feramu" 8, 2003, p. 217 Kazumasa Wakimoto et al. “Materials and Processes” 18, 2005, p. 1112 Naito Masaaki et al. “Iron and Steel” 87, 2001, p. 357 “Biomass Ratio Calculation Method, Enforcement Regulations, Article 7, Paragraph 2” Agency for Natural Resources and Energy, February 2003 The Japan Institute of Energy "Biomass Handbook" Ohm Corporation 2002 “Biomass Nippon (FY2004 Biomass Nippon Biomass Nippon Strategy Promotion Project)” 2004 "2004 Iron and Steel Statistics Manual" Japan Iron and Steel Federation "Statistical data: Production volume of pig iron in 2005" Japan Iron and Steel Federation

  In the coke production technology that uses a biomass material in a chamber-type coke oven, the biomass material is first heat-treated at 150 to 400 ° C. in advance as described in Patent Document 1 and the like. Next, the residual char generated by pyrolysis is pulverized to a predetermined particle size, mixed with ordinary blended coal, charged into a coke oven, and dry-distilled to produce coke. However, there is a problem in that the production equipment becomes complicated in the method in which the biomass raw material is heat-treated in advance to char and the residual char is pulverized to a predetermined particle size and charged into a normal chamber furnace coke. In addition, after cooling the pre-heated residual char to near room temperature, mixing it with blended coal again, charging it into a coke oven, and dry-distilling (heating treatment) to about 1100 ° C in the furnace is inefficient. Is clear. Further, the char residue is not caking as in the case of woody biomass, and when it is blended, the coke strength decreases. Therefore, it is necessary to increase the caking property by increasing the blending ratio of strong caking coal in the blended charcoal, or to add an expensive caking agent. Further, the pyrolysis char becomes porous due to the devolatilization during the heat treatment process, and when pulverized to a predetermined particle size, a large amount of fine powder of 0.5 mm or less is generated, and the yield is deteriorated. In addition, when mixed with ordinary blended coal and charged into a coke oven, the amount of carbon deposited on the coke oven wall increases due to the generation of fine powder, which impedes stable operation of the coke oven. For this reason, there is a problem that the coke production process becomes complicated and the production cost and the blended coal price increase due to an increase in energy consumption.

On the other hand, Non-Patent Document 2 discloses a method for operating a blast furnace in which wood biomass is blown together with pulverized coal from the tuyere of the blast furnace to reduce the amount of pulverized coal and lump coke charged from the top of the furnace and CO ₂ emissions. ing. By the way, woody biomass is characterized by a higher water content than pulverized coal. Table 1 shows a comparison of moisture content, organic matter ratio, ash content, and calorific value of typical biomass (see Non-Patent Document 5).

  From Table 1, it is recognized that the water content of the woody biomass is 30 to 60 mass%. In order to inject solid fuel from the tuyere of the blast furnace and reduce the coke consumption efficiently, the tuyere tip temperature usually needs to be controlled at 2000 ° C. or higher. When the temperature is lower than 2000 ° C., the injected fuel does not burn sufficiently in the tuyere tip space and partially chars in an unburned state. When the biomass moisture content is high, if the other air blowing conditions are constant, the latent heat of vaporization of water of 2500 kJ / kg (see Non-Patent Document 4) is lost at the tuyere. Therefore, the tuyere tip temperature decreases according to the amount of injection, and stable combustion of the injected fuel becomes difficult. For this reason, measures in blast furnace operation such as an increase in blowing temperature, an increase in oxygen enrichment rate, and dehumidification blowing are required, and all of them lead to cost increase.

  In order to solve such a problem, Patent Document 2 proposes a method of drying sewage sludge, mixing it with pulverized coal, and blowing it. As a result, compared with the case where the moisture content sludge of 90 mass% or more shown in Table 1 is blown in, the reduction of the tuyere temperature is suppressed and a significant improvement in combustion efficiency can be expected. However, sludge in the biomass has an ash content of 20 mass% or more as shown in Table 1, and is 20 times or more the content of wood biomass. For this reason, sludge ash accumulates in the furnace core or the cohesive zone in the tuyere space compared with wood biomass blowing, and the air permeability and liquid permeability are relatively deteriorated. If the drying heat source required for pre-drying depends on fossil fuel, heat energy is required at this stage. Therefore, steel production energy including this heat requires changes in other blast furnace operating conditions, such as an increase in blowing temperature, an increase in oxygen enrichment rate, dehumidification blowing, etc., with insufficient drying of sludge. It may not lead to rationalization of steel manufacturing costs.

  On the other hand, Non-Patent Document 3 shows that the method of reducing the FeO-Fe reduction equilibrium temperature of the shaft thermal storage zone of the blast furnace by using highly reactive coke blast furnace and reducing the reducing material ratio by the analysis of the general material and heat balance model Presents. This result clarifies that increasing the reactivity of coke leads to a reduction in the reducing material ratio. However, highly reactive coke makes the coke structure porous in order to increase the reactivity in the production process. As a result, the coke strength tends to decrease. In FIG. 6 of Patent Document 3, the same tendency is shown. For this reason, it is important for high-reactivity coke to maintain its strength and reactivity within the desired range at the same time in order to continue stable operation under the low reducing agent ratio of the blast furnace.

  As described above, when using wood biomass at steelworks, there are problems such as reduced coke strength and complication of the coke production process, and when injecting wood biomass from the blast furnace tuyere, the tuyere tip temperature There are problems such as lowering and difficulty in stable combustion of injected fuel, both of which greatly increase pig iron production costs.

  Therefore, an object of the present invention is to solve such problems of the prior art and provide a method of effectively using woody biomass in an ironworks, that is, a blast furnace operating method and woody biomass using woody biomass as raw materials. The object is to provide a method for producing coke as a raw material.

  Another object of the present invention is to achieve a reduction in the reducing material ratio of the blast furnace by using woody biomass.

  In the present invention, in order to solve the problems of the method of injecting biomass from the tuyere of the blast furnace and the highly reactive coke charged from the top of the blast furnace, the woody biomass as a raw material is dried in advance, and this is reacted with the highly reactive coke. Used as raw material and tuyere blown raw material. This makes it possible to improve the combustion efficiency of solid fuel in the tuyere compared to the conventional similar technology, and to reduce the blast furnace heat preservation zone temperature by producing coke that maintains strength and increases reactivity, and reduces the reducing material ratio. Achieved.

The features of the present invention are as follows.
(1) A blast furnace operating method using woody biomass as a raw material, wherein the woody biomass is heated and dried and used as a blast furnace raw material.
(2) The blast furnace operation method using the woody biomass as a raw material according to (1), wherein the woody biomass is dried so that the water content is 5 mass% or more and less than 30 mass%.
(3) The method for operating a blast furnace using the woody biomass as a raw material according to (1) or (2), wherein the woody biomass is dried using exhaust heat of 300 ° C. or less.
(4) A blast furnace operating method using the woody biomass as described in any one of (1) to (3), wherein the dried woody biomass is pulverized and blown from the tuyere of the blast furnace.
(5) The dried woody biomass is pulverized and molded together with coal to form a molded body, and the molded body is charged together with coal into a coke oven and dry-distilled coke is charged into a blast furnace. A method for operating a blast furnace using the woody biomass according to any one of (1) to (3).
(6) The dried woody biomass is pulverized and molded with coal to form a molded body. The sieve obtained by sieving the molded body is charged into a coke oven together with coal, and the coke produced by dry distillation is used as a blast furnace. The blast furnace operation method using woody biomass as a raw material according to any one of (1) to (3), wherein the sieved material that has been charged and sieved is blown into a blast furnace from a tuyere.
(7) The method for operating a blast furnace using woody biomass as a raw material according to (6), wherein the sieve mesh for sieving is 3 to 6 mm.
(8) Crushing the dried woody biomass, molding it with coal to form a molded body, charging the molded body with coal into a coke oven, and dry-distilling the produced coke into the blast furnace, The method for operating a blast furnace using woody biomass as a raw material according to any one of (5) to (7), wherein the amount of coke is less than 80 mass% of the total amount of coke to be charged.
(9) The woody biomass is pulverized to a particle size of 3 mm or less, mixed with coal and molded, and the volume of the molded body is 10 cm ³ or more and 50 cm ³ or less, and the bulk density is 0.8 g / cm ³ or more and 1.1 g. / cm ^3, characterized in that below (5) to blast furnace operation method woody biomass according as the raw material in any one of (8).
(10) The blast furnace operating method using the woody biomass as described in any one of (5) to (9), wherein the pulverized woody biomass is molded together with coal and a binder.
(11) Wood biomass is heated and dried, then pulverized, molded with coal to form a molded body, and the molded body is charged with coal into a coke oven and dry-distilled as a raw material. Coke production method.
(12) The woody biomass is pulverized to a particle size of 3 mm or less, mixed with coal and molded, and the volume of the molded body is 10 cm ³ or more, 50 cm ³ or less, and the bulk density is 0.8 g / cm ³ or more. The method for producing coke using woody biomass as a raw material according to (11), characterized by being 1 g / cm ³ or less.
(13) The method for producing coke using the woody biomass as a raw material according to (11) or (12), wherein the pulverized woody biomass is molded together with coal and a binder.

By applying the present invention to an integrated steelworks in Japan as a whole, the effects of reducing the amount of coal used and reducing CO ₂ emissions are significantly increased. That is, approximately 14.8 million tons of woody biomass is generated annually in Japan, of which the amount that is unused and discarded reaches 7.40 million tons (see Non-Patent Document 6). This amount corresponds to 5.1 million tons in terms of coal calorific value (see Non-Patent Document 4). On the other hand, the amount of coal used in the steel industry in Japan is 65 million tons (see Non-Patent Document 7). If woody biomass is used as a coke raw material according to the present invention, the amount of CO ₂ reduction by carbon neutral is
2.394 (t-CO ₂ / t-coal) × 510 (10,000 t / y) ≈1220 (10,000 t-CO ₂ / y)
It becomes. In addition, when wood biomass (moisture 5 mass%) is blown into the blast furnace at 40 kg / pig-t, the amount of pulverized coal blown by wood biomass, which is carbon neutral, 38 kg / pig-t (40 kg / pig-t × 0.95) In addition, it is possible to reduce the reducing material ratio of 11 kg / pig-t (breakdown: PCI ratio of 3 kg / pig-t, coke ratio of 8 kg / pig-t) by using 80 mass% of highly reactive coke in the blast furnace from Table 7 described later. As a result, considering the amount of pig iron production of 82940 thousand tons in 2005 (see Non-Patent Document 8), coal use due to coke ratio reduction effect by using woody biomass as a substitute for pulverized coal injection and highly reactive coke feedstock The amount reduction effect is
(0.038 (coal-t / pig-t) +0.003 (coal-t / pig-t) +0.008 (coke-t / pig-t) /0.75 (coke-t / coal-t) ) × 82940 thousand (pig-t / y) = 4288 thousand (coal-t / y)
Can be evaluated. In this way, the present invention presents a technique for simultaneously achieving energy saving and reduction of environmental emission CO _{2 in the} steel industry by effectively using woody biomass, which has been a problem in use in the steel industry.

The graph which shows the relationship between the water | moisture content of biomass, and a tuyere tip maximum temperature. The graph which shows the relationship between the compounding rate of a highly reactive coke, and a reducing material ratio. The whole process outline | summary figure of this invention which shows drying by exhaust heat of biomass, mixed agglomeration with coal, high-reactive coke production and use to a blast furnace, and blast furnace injection of dry biomass. The graph which shows the result of having dried the biomass with which supply amount differs with a rotary kiln using the unused waste heat of a sintering machine cooler. The graph which shows the superficial velocity in the kiln of the dry exhaust gas obtained according to biomass supply amount when drying biomass with a rotary kiln. The graph which shows the result from which drying behavior changes with biomass particle size when drying biomass in a rotary kiln. The graph which shows the drying behavior when changing the amount of dry gas according to the initial moisture content of the biomass charged to a rotary kiln. The graph which shows the influence on the coke property of the method of simply adding biomass to coal and the method of molding a mixture of coal and biomass and blending the coal. The graph which shows the relationship between the moisture content of biomass, and coke property by the method of shape | molding the mixture of coal and biomass, and mix | blending coal. The graph which shows the relationship between the particle size of biomass, and a coke property by the method of shape | molding the mixture of coal and biomass, and mix | blending coal. The graph which shows the relationship between the compounding ratio of the biomass in the case of mixing and shaping | molding coal and biomass, and manufacturing a molding, and the property of a molding. The graph which shows the compounding ratio to the coal of a molding, and a coke property. The graph which shows the temperature and gas composition in the raceway space at the time of blowing biomass from a tuyere. The blowing condition 1 indicates a case where only pulverized coal is blown, a blowing condition 2 indicates a case where undried biomass is blown, and a blowing condition 3 indicates a case where dry biomass is blown. The graph which shows the result of having analyzed the way of thinking of the blast furnace fuel ratio when the thermal preservation zone temperature of a blast furnace fell by the list diagram. Schematic of a biomass drying experiment apparatus simulating a great furnace system. The graph which shows the experimental result of a great system. The graph which shows the experimental result of a great system. The graph which shows the experimental result of a great system. The graph which shows the experimental result of a great system.

  In the present invention, the dried wood biomass material is used as a blast furnace material or a coke material. The drying of the woody biomass is preferably performed using exhaust heat of 300 ° C. or less, and the low-temperature cooler exhaust heat of the sintered ore sintering machine can be used particularly effectively. The blast furnace raw material is preferably blown from the blast furnace tuyere. As coke raw material, after mixing dried woody biomass raw material into coal, it is agglomerated with a molding machine, this molded product is mixed with ordinary coal for coke and charged into a coke oven to produce coke. Is preferred. In the present invention, a mixture of biomass raw material and coal is formed into a high-density molded product by mechanical pressure. Therefore, the adhesion between the biomass raw material and the coal particles in the molded product is improved, and the strength of the coke is further improved by using a binder having caking properties at the time of molding. When a high-density molded product is mixed with normal blended coal at a predetermined ratio and charged into a coke oven, the coal charging density increases, so that the caking property of coal is improved and coke strength is improved. In addition, since the biomass raw material is charged into the coke oven as a molded product, the biomass is uniformly dispersed in the coke oven and segregation is suppressed, thereby reducing the variation in coke quality in the furnace area, which was a conventional problem. The Moreover, since the biomass raw material is not char by preheating, carbon loss due to loss of heat energy and generation of fine powder does not occur. Further, since coke is produced by blending biomass raw material with coal, the porosity of coke due to gasification increases during the heat treatment process of biomass. Moreover, the optical structure of the residual carbide from biomass is highly reactive due to the isotropic component, and the reactivity can be increased while maintaining the strength of coke. These are coke production methods that can be realized for the first time by the present invention.

  When producing coke as described above, after mixing wood biomass raw material with coal, the molded product agglomerated with a molding machine is sieved, and the sieve top is charged together with coal into a coke oven and dry-distilled. It is preferable to charge the produced coke into a blast furnace and blow the screened sieve under the blast furnace from the tuyere.

  The woody biomass used in the present invention is a biomass or the like classified as “woody” in Table 1 (non-patent document 5), and is waste wood, thinned wood, pruned trees, etc., and has a moisture content It is a biomass with high ash content. The woody biomass used in the present invention may include a woody biomass whose water content has been reduced due to natural drying or the like in a part thereof, and in such a case, the water content of the woody biomass as a whole is less than 30 mass%. In some cases. Hereinafter, “woody biomass” is simply referred to as “biomass”.

  Although drying of biomass can be performed using an arbitrary apparatus, it is preferable to use drying in a rotary kiln using a drying gas, a moving grate, a fluidized bed, or the like.

  In the present invention, the biomass is preferably dried to a moisture content of 5 mass% or more and less than 30 mass%.

  The moisture content after drying of the biomass is preferably 5 mass% or more and less than 30 mass% for the following reasons. When biomass is blown from the tuyere together with pulverized coal under constant blowing conditions, the tuyere tip temperature changes according to the moisture content. A hot model that simulates the tuyere of a blast furnace and is capable of high-temperature blowing and fuel blowing, equivalent to 40 kg / t (dry weight conversion) of biomass with different moisture contents under the fuel blowing conditions shown in Table 2, and equivalent to 78 kg / t of pulverized coal The maximum temperature at the tuyere was measured with a blow-in thermometer. The result is shown in FIG.

  According to Fig. 1, the tuyere tip raceway condition is such that the tuyere tip maximum temperature decreases as the moisture content in the biomass increases. In this measurement result, when the biomass moisture exceeds 30 mass%, the temperature drops by about 100 ° C., and the combustion of the injected fuel becomes incomplete in the raceway space. As a result, unburned char is deposited on the coke bed, and the blowing pressure tends to increase.

  From these experimental results, it is appropriate that the moisture content of the biomass is less than 30 mass%, desirably 25 mass% or less that can achieve stable combustion. More preferably, by setting it to 20 mass% or less, the amount of decrease in the tuyere tip temperature is small, and the blast furnace operation can be performed stably. On the other hand, it is determined from the exposure test in the atmosphere that the amount of water that does not ignite during biomass transportation is 5 mass% or more. Therefore, when these are combined, it is desirable that the moisture content of the biomass is controlled to be 5 mass% or more and less than 30 mass%.

  The biomass is preferably adjusted to a particle size of 100 mm or less to reduce moisture. Here, the biomass having a particle size of 100 mm or less is the state of biomass under a sieve passing through a 100 mm (or less) sieve mesh. By adjusting the particle size to be equal to or smaller than the predetermined particle size and drying, the water content contained in the biomass is easily released, and the drying efficiency is increased. The optimum particle size varies depending on the drying method, but when a rotary kiln having a furnace length of about 10 m is used for drying, a particle size of about 100 mm or less is appropriate.

  The atmospheric temperature for drying the biomass is preferably 100 ° C. or higher and 300 ° C. or lower. Moisture in the biomass exists as water adhering to the particle surface or trapped moisture in the pores due to the porous nature. For this reason, when the biomass is heat-treated, the attached water on the biomass surface and the moisture contained in the pores evaporate and dehydrate at around 100 ° C, and the biomass, which is an organic substance, starts thermal decomposition at about 300 ° C to 500 ° C. , Char (amorphous carbon) while generating gas, tar and generated water. Accordingly, the heating temperature of the biomass is suitably 300 to 500 ° C. for charring, but is preferably 300 ° C. or less in the present invention for the purpose of drying the biomass. On the other hand, if it is less than 100 ° C., the drying efficiency of the woody biomass is lowered, and therefore the drying temperature is preferably 100 ° C. or higher.

  For drying such biomass, it is preferable to use exhaust gas at a relatively low temperature (for example, 300 ° C. or lower). Exhaust heat of 300 ° C. or less cannot normally be effectively used because heat recovery by steam recovery or the like is difficult, but in the present invention, it can be effectively used for drying biomass. An exhaust gas of 200 ° C. or lower is more preferable from the viewpoint of heat recovery.

As the relatively low temperature exhaust gas, for example, medium / low temperature exhaust heat discharged from a sintering machine cooler for producing sintered ore can be used. This is because the cooler exhaust heat gas is basically composed of high-temperature air, has a low moisture content and is excellent in drying efficiency, and the ratio of the amount of unused external exhaust gas at 300 ° C or less is the total exhaust heat. This is because it is 60% or more. In addition, as shown in Non-Patent Document 1, woody biomass is not charred under such dry conditions. Charging is difficult in the atmosphere and requires a large investment in equipment including gas treatment during the charing process. Utilizing exhaust heat of 300 ° C. or less, which is difficult to use effectively, for drying biomass is a highly desirable embodiment because it does not generate CO ₂ by heating for drying.

  The dried biomass can be pulverized and used as a blown raw material blown from the tuyere of a blast furnace, or molded together with coal to form a molded body as a coke raw material. The pulverization is preferably about 10 mm or less when using the blown raw material, and about 3 mm or less suitable for molding when using the coke raw material.

For example, a molded product that is formed by mixing biomass and coal is blended with dried biomass raw material, mixed with a binder and then mixed in a mixer, and then supplied to a double roll molding machine. A molded product having a body volume of 10 cm ³ or more and 50 cm ³ or less and a bulk density of 0.8 g / cm ³ or more and 1.1 g / cm ³ or less is produced. This molded product is mixed with blended coal in the range of 5 to 30 mass%, and charged into a coke oven to produce highly reactive coke having the same strength as ordinary coke.

As a method for producing a molded product, a pan pelletizer or the like can be used in addition to a double roll type molding machine. Adhesion of biomass material and coal particles in the molded product to produce a high-density molded product by pressurizing the mixture containing biomass, coal and, if necessary, a binder with mechanical pressure using a double roll molding machine The strength of coke is improved by using a binder that has improved caking properties and has caking properties during molding. If the volume of the molded body is 10 cm ³ or less, the productivity of the molded product is low when the particle size of the biomass is 3 mm or less, and if it is 50 cm ³ or more, segregation of the molded product occurs when it is charged into the coke oven. It causes quality variation. When the bulk density of the molded product is 0.8 g / cm ³ or less, the strength of the molded product is reduced, and it cannot be endured for conveyance to the coke oven, and pulverizes. When the bulk density is 1.1 g / cm ³ or more, the addition rate of expensive binders is increased. There is a problem that it is necessary to increase the molding pressure of the molding machine or to increase the manufacturing cost of the molded product. Also, when a high-density molded product is mixed at a predetermined ratio with normal blended coal and charged into a coke oven, the coal charging density increases, so that the coal cohesiveness is improved and coke strength is improved. . In order to charge the biomass raw material into the coke oven as a molded product as it is, it is uniformly dispersed in the coke oven, segregation is suppressed, and variations in coke quality are reduced. However, if the blending ratio of the molded product into the blended coal is 40 mass% or more, the charging density into the coke oven is lowered because it is far from the closest packing condition, and the coke strength is lowered along with the increase in the amount of biomass added. . Furthermore, there is an advantage that carbon trouble due to loss of heat energy and generation of fine powder does not occur because the biomass raw material is not charred by preheating.

The coke produced as described above is highly reactive coke. In the highly reactive coke, the coke gasification reaction shown in the following formula (a) becomes active in the blast furnace heat preservation zone region (region in which the temperature of gas and solid is approximately 1000 ° C.).
C (coke) + CO ₂ = 2CO (a)
Since the reaction of formula (a) is an endothermic reaction, the use of highly reactive coke tends to lower the temperature of the heat preservation zone. It is known that the reduction of iron oxide represented by the following formula (b), which is the main component in this region, reaches almost equilibrium because of the long heat conservation zone region.
FeO + CO = Fe + CO ₂ (b)
In equation (b), as the equilibrium temperature decreases, the equilibrium gas oxidation degree (= CO ₂ / (CO + CO ₂ (−)) shifts to the high oxidation degree side, in other words, to the high gas utilization rate side, so the reducing material ratio decreases. The above is the reason why the ratio of reducing material can be reduced by introducing blast furnace operation technology using highly reactive coke made from woody biomass. The idea of lowering is confirmed by experiments in Non-Patent Document 3, and it is clear that highly reactive coke using biomass as a raw material contributes as an achievement means.

The present invention achieves stable operation, reduced reductant ratio, and reduced CO ₂ emissions compared to conventional blast furnace operations that have problems with reduced coke strength and tuyere temperature due to the use of biomass. .

  When the coke produced as described above is charged into a blast furnace and used as a raw material, the charging ratio into the blast furnace is preferably less than 80 mass% of the total amount of coke charged into the blast furnace. Coke produced by co-molding biomass as a raw material with coal and carbonizing with coal (mixed coal) in a coke oven is more reactive than ordinary coke, and is described in the above formulas (a) and (b). For reasons, it has been recognized that it contributes to reducing the reducing material ratio of the blast furnace (see Non-Patent Document 3). FIG. 2 shows the results of evaluating the reducing material ratio by blending high-reactivity coke with normal coke based on the blast furnace operating conditions shown in Table 7 (described later). According to FIG. 2, as the high reactive coke blending ratio produced using biomass as a raw material increases, the thermal storage zone temperature of the blast furnace decreases, resulting in a constant shaft efficiency (a parameter indicating the degree of FeO to Fe reduction equilibrium). Originally, the reducing material ratio decreases. This tendency decreases almost linearly as the high reactive coke content increases. However, when the blending ratio is 80 mass% or more, the reducing material ratio tends to increase. The reason for this is that the reducing material ratio decreases according to the blending ratio, but in parallel with this, the heat flow ratio (ratio of the enthalpy on the solid side to the enthalpy of the gas in the blast furnace shaft region) representing the heat transfer characteristics in the blast furnace is The heat transfer is not stably performed from the gas side to the solid side. As a result, stable blast furnace operation becomes difficult, and at a high reactive coke compounding ratio of 80 mass% or more, operation that deliberately deteriorates the shaft efficiency, in other words, stable operation cannot be realized unless the reductant ratio is high. In this evaluation, the heat flow ratio is 0.900 (−) or less and needs to be controlled. For this control, it was confirmed that the blending of 80 mass% or more hinders stable operation. From these evaluations, the range of the desirable mixing ratio is a high reactive coke blending ratio of 5 mass% or more, at which the temperature of the heat preservation zone starts to be reduced, and 80 mass% or less, in which the reducing material ratio keeps decreasing.

An outline of a manufacturing process according to an embodiment of the present invention is shown in FIG. The woody biomass or woody biomass chip adjusted to a particle size of 10 mm or less in order to improve the drying efficiency is once accumulated in the biomass chip tank 1 and transferred to the drying step 2 in order to increase energy efficiency when used in the subsequent iron making process. Drying is performed in a rotary kiln, moving grate, fluidized bed or the like. Note that the heat source used for drying does not depend on fossil fuels, but uses the exhaust heat of the steel mill, for example, the unused 100-300 ° C. exhaust heat discharged from the cooler 3 of the sintering machine, thereby improving the energy efficiency of the entire ironmaking process. It leads to improvement. Biomass dried to a moisture content of 5 mass% or more and less than 30 mass% is stored in a dedicated storage tank 5 to prevent spontaneous ignition. Biomass is supplied from the dedicated storage tank 5 to the crushing / pulverizing machine 6 where it is pulverized to a particle size of 3 mm or less. Next, the pulverized biomass is charged into the mixer 9 together with the coal 7 and the binder 8 and mixed uniformly, and then granulated or agglomerated in the molding step 10. No. 10 requires a briquetting machine or pelletizer and an agglomeration device having equivalent functions. A molded product having a bulk density of 0.8 to 1.1 t / m ³ by mixing and molding a low bulk density of 0.4 to 0.6 t / m ³ with coal by passing through 10 molding steps. Is manufactured. Since the bulk density of the molded product is higher than the bulk density of the coal powder, it has physical properties suitable for the subsequent coking process and the blowing process into the blast furnace. If the bulk density is 0.8 t / m ³ or less, the powder is pulverized in the course of conveyance to the coke oven, so that segregation with coal proceeds in the coke oven and the yield after dry distillation is reduced, and the productivity is lowered. On the other hand, if it is 1.1 t / m ³ or more, the mechanical molding pressure becomes high, the equipment becomes expensive, and the addition rate of the binder needs to be increased, resulting in an increase in production cost. The use of cohesive coal tar pitch as a binder in combination with the uniform mixing of coal powder and biomass and the coating of the surface layer of biomass during agglomeration forms pores while maintaining coke strength. However, this is an important operation for producing highly reactive coke. The biomass agglomerated with coal is sieved in the sieving step 11, coarse particles having a particle size of 5 mm or more are sent to the coke oven 13, and fine particles having a particle size of less than 5 mm are sent to the biomass storage tank 17. Biomass is cut out from the biomass storage tank 17 at a ratio of a predetermined amount and blown into the blast furnace 14 from the tuyere together with the pulverized coal 18 under the management of the tuyere tip temperature, thereby contributing to the reduction of the amount of lump coke used. This blowing method can increase the amount of blowing under controlled conditions with a tip temperature of 2000 ° C. or higher compared with the case where the biomass is blown in an undried state, and as a result, the amount of substitution with pulverized coal is all from the tuyere. It can be increased up to 20 mass% of the solid fuel injection amount. Moreover, compared with the method of drying biomass using fossil fuel, it uses an unused mid- and low-temperature exhaust heat, which makes the drying method more energy efficient.

  Next, the present invention will be described with reference to an example in which model calculation is used in combination.

[Example 1]
When woody biomass is dried in a rotary kiln, the drying behavior is affected by the drying temperature, the dry gas flow ratio to biomass, the initial biomass moisture, the biomass particle size, and the like. Among these factors, the results of drying experiments on the operating factors important for drying are shown. The experiment was performed using a rotary kiln having a diameter of 3 m and a length of 10 m. Table 3 shows other main operating conditions.

FIG. 4 shows the gas temperature in the furnace and the moisture removal rate of biomass when 200 ° C. exhaust gas was blown into the kiln under the conditions of a gas quantity basic unit of 1300 Nm ³ / t and a biomass average particle size of 3 cm. From this, when the biomass supply amount is 30 t / h, the drying is completed at a point of about 3 to 4 m in the kiln, but when the supply amount is 60 t / h, the drying is gradually completed at the point of 8 m. Operating conditions with a large supply amount are desirable from the viewpoint of productivity of dry biomass. However, if the biomass supply is increased under a constant gas unit, the gas supply to the kiln inevitably increases. In this series of experiments, the gas flow rate in the kiln increases. FIG. 5 shows the relationship between the biomass supply amount and the empty gas flow rate in the kiln. In this series of experiments, the amount of biomass scattered in the kiln begins to increase due to fluidization at a superficial gas flow rate of 2.0 m / s or more, and the yield of dry biomass decreases significantly at 2.5 m / s or more. Therefore, under the operating conditions shown in Table 3, the biomass throughput is preferably 30 to 50 t / h.

[Example 2]
An experiment was conducted to determine the appropriate particle size range of biomass supplied to the kiln from the effect of biomass particle size on drying behavior. Based on the operating conditions shown in Table 3, a drying test was conducted under the conditions of 35 mass% of initial biomass moisture, 1300 Nm ³ / t of gas unit, and 50 t / h of biomass supply, and the results are shown in FIG. When the particle size is smaller than this result, the drying speed is high because the specific surface area is large. For example, when the particle size is 1 cm, the drying is completed at about 4 m from the biomass kiln charging portion. On the other hand, when the particle size is increased, the drying is delayed with a particle size of 7 cm. For this reason, it is desirable that the particle size of the biomass is small, but in this case, there arises a problem that the yield of the product deteriorates due to the spread of the particle size distribution. If a small particle size is required when the chips are received, the adjustment of the particle size is costly and the economical advantage is lost. On the other hand, as shown in FIG. For this reason, the appropriate particle size of the desired receiving biomass is determined to be in the range of 1 to 10 cm.

[Example 3]
Figure 7 shows the effect of initial biomass moisture content on drying characteristics by experiments based on waste heat supply basic unit of 1300 Nm ³ / t, biomass supply of 40 t / h, biomass average particle size of 3 cm, and operating conditions in Table 3. The obtained result is shown. As a result, when the initial biomass moisture content is 30 mass%, the drying is completed at approximately 7 m from the biomass charging port of the kiln. However, when the water content is 35 mass%, the drying is no longer completed under these conditions, so that the waste heat supply basic unit of 1500 Nm ³ / t is necessary. Further, if the moisture is 40 mass%, 1700 Nm ³ / t is required similarly. In this case, the gas superficial velocity in the kiln was 2.0, 2.4, and 2.7 m / s, respectively. Therefore, as in the case of Example 1, as the moisture content increases, the gas superficial velocity increases. As a result, the fluidization of biomass in the kiln becomes remarkable, and the dry biomass yield deteriorates. Under the present experimental conditions, it was confirmed that the initial biomass moisture was desirably 40% by mass or less, and desirably the biomass moisture condition controlled to 35% by mass or less.

[Example 4]
After the dry biomass, coal and binder were mixed and molded, the molded product was blended with ordinary blended coal for coke production, and charged into a 250 kg dry distillation test furnace to conduct a coke production test.

  Coal and biomass were cut out at a predetermined ratio, combined with a binder coal tar soft pitch (addition of 5 mass% of outer frame), charged into a KB mixer, mixed, and then molded with a double roll molding machine. The molding pressure of the molding machine was a linear pressure of 1000 kg / cm, and the molded product was a Macek type (width: 43 mm, length: 25 mm, thickness: 18 mm).

The molded product was mixed with ordinary blended coal at a predetermined ratio, and then charged into a 250 kg dry distillation test furnace and subjected to dry distillation at a dry distillation temperature of 1100 ° C. to produce coke. As the properties of coke, coke strength (JIS drum strength DI30 / 15), CO ₂ reactivity (CRI) and strength after CO ₂ reaction (CSR + 9.5) were measured and evaluated. Table 4 shows the particle size distribution of the raw coal and biomass used.

  Fig. 8 shows the coke produced by mixing the biomass raw material with coal, producing a molded product and charging it into the coke oven (molded compounding method), and simply mixing the biomass and charging it into the coke oven (biomass simple compounding method). The effect on properties was shown. The coke properties of ordinary coal for coke without adding biomass (ordinary charcoal) are also shown.

A molded product of biomass and coal was manufactured using a double roll molding machine for mixing by adding coal tar soft pitch (addition of 5 mass% of outer frame) as a binder to biomass (17 mass%) and ordinary blended coal (83 mass%). . The molded product was blended in 30% by mass into ordinary coal for coke and charged into a 250 kg dry distillation test furnace to produce coke. In the method of simply blending the biomass feedstock insufficient melting of the coal particles to the biomass does not exhibit caking during heating, coke strength (DI30 / 15) and CO ₂ strength after reaction (CSR) is reduced did. However, the coke reactivity is increasing due to the high porosity of coke due to the devolatization of biomass and the high reactivity (CRI) of the residue. On the other hand, after mixing biomass raw material, coal and binder, molding, mixing with ordinary blended coal to produce coke, while maintaining coke strength and CO ₂ reaction strength almost the same as normal coke, Coke reactivity is increasing.

[Example 5]
FIG. 9 shows the relationship between the moisture content of biomass and coke properties in the molded product produced by the same method as the molded product production method of Example 4. Biomass and coal having different water contents were mixed and molded, and then blended into a normal coke blending coal at a constant ratio of 30 mass%, and charged into a 250 kg test dry distillation furnace to produce coke. As for the coke properties, the higher the moisture content of biomass, the lower the coke strength and strength after CO ₂ reaction. If the moisture content of the biomass is high during the heating process in the coke oven, the molded product will collapse when the moisture evaporates. Therefore, in addition to the increase in latent heat of vaporization accompanying the dehydration of high-moisture biomass, it is assumed that the adhesion between the biomass and coal particles is reduced and the meltability is hindered due to the low bulk density, resulting in a decrease in coke strength. . Accordingly, the moisture content of the biomass is 10 mass% or less, and preferably in the range of 5 mass% to 10 mass% from the ignitability of the biomass after drying.

[Example 6]
FIG. 10 shows the influence on the particle size of biomass and coke properties in the molded product produced by the same method as the molded product production method of Example 4. After mixing and molding biomass and coal having different particle diameters, the molded product was blended into a normal coke blending coal at a constant ratio of 30 mass%, and charged into a 250 kg test dry distillation furnace to produce coke. As for the coke properties, the coke strength and the strength after CO ₂ reaction decrease as the particle size of the biomass increases. The larger the particle size of the biomass, the larger the particle size difference with coal, so that it is not uniformly mixed at the time of blending, and the meltability between the biomass and the coal particles decreases, so the coke strength decreases. Biomass is not meltable, and moisture and gas escape during heat treatment, so it exists as a porous inert substance in the coke mass. For this reason, it is presumed that when the particle size of the biomass increases, the weak inert material also increases and the coke strength decreases. In addition, woody biomass has more fiber and elasticity and is less pulverizable than coal, etc. For example, when pulverizing to 1.5 mm or less, there is a problem that costs such as pulverization and maintenance of pulverization equipment are increased. .

  From this, it is desirable that the particle size of the biomass be pulverized to 6 mm or less, preferably 3 mm or less, which is the maximum particle size of ordinary coal for coke.

[Example 7]
FIG. 11 shows the relationship between the blending ratio of biomass in the molded product and the influence on the molded product properties in the same manner as the molded product manufacturing method of Example 4. As the properties of the molded product, crushing strength, trommel strength and molded product yield (+5 mm) were measured. When the blending ratio of biomass is increased, the crushing strength and the trommel strength tend to decrease, and the amount of biomass added is at least 25 mass%, preferably 20 mass%, considering pulverization due to impact in the process of conveying the molded product to the coke oven. The following is desirable. On the other hand, a blending ratio of 30% by mass or more is not preferable because a back spring phenomenon after molding occurs, the molded product is cracked, and the molded product yield is significantly reduced.

[Example 8]
FIG. 12 shows the relationship between the blending ratio of the molded product and the coke properties when the coke was produced by blending the molded product produced by the method for producing the molded product of Example 4 into an ordinary coal for coke. It was confirmed that the coke strength and strength after CO ₂ reaction did not change so much until the blending ratio of the molded product was about 30 mass%, but greatly decreased at 40 mass%. When the molding compounding ratio increases, it is estimated that the amount of biomass added increases, the porosity increases, and the coke strength decreases. However, the reactivity of coke is increased by increasing the amount of moldings. Thus, in order to produce coke having high reactivity while maintaining the same strength as normal coke, the blending ratio of the molded product is preferably 30 mass% or less. Moreover, it is possible to improve coke strength and strength after CO ₂ reaction by increasing the amount of binder added. Furthermore, by blending a biomass material having a hydrogen content higher than that of coal, a gas having a higher hydrogen concentration than normal by-product gas is generated.

[Example 9]
In the present invention, it is intended to reduce the thermal load during blast furnace blowing by pre-drying of biomass. FIG. 13 shows the results of evaluating the gas composition and temperature distribution in the blast furnace raceway space when the biomass is blown in an undried state and when blown dry, using a mathematical model based on the material and the heat balance. Table 5 shows chemical components of the wood biomass for blowing. Table 6 shows the conditions for blowing the solid fuel from the tuyere. Accordingly, the blowing condition 1 is a reference blowing condition, in which only pulverized coal is blown at 118 kg / t. On the other hand, blowing condition 2 is a case where biomass having a water content of 30 mass% is blown in an undried state at 40 kg / t. At this time, the blowing quantity of pulverized coal is set to 78 kg / t, and the entire blowing quantity is adjusted to blowing condition 1. The blowing condition 3 is a condition within the scope of the present invention. Although it is the same as blowing condition 2, it is the conditions which blow in the biomass dried to water content 5mass% beforehand.

  From FIG. 13, the tuyere tip maximum temperature in blowing condition 1 is 2045 ° C., but in blowing condition 2 in which the biomass is blown in undried, the maximum temperature remains at 1980 ° C. due to the increase in the moisture content. For this reason, combustion of the solid fuel in the raceway space is suppressed, and accumulation of unburned char in the lower blast furnace cohesive zone and the furnace core located in front of the raceway as well as deterioration of air permeability and liquid permeability are easily expected. The The deterioration of the replacement ratio with the coke coke due to this is also estimated. On the other hand, under the blowing condition 3, which falls within the scope of the present invention, which is previously dried with unused exhaust heat outside the system, the heat of moisture decomposition is reduced in the raceway, so the maximum temperature rises to 2066 ° C. As a result, it is presumed that the solid fuel combustion in the raceway is improved and the replacement rate with the lump coke is improved.

[Example 10]
Highly reactive coke can be produced by pre-mixing agglomeration of biomass and coal. It was verified in the blast furnace material / heat balance summary model (list model) that the reduced reactive material ratio of the blast furnace can be achieved by replacing the highly reactive coke produced here with conventional coke and using it in the blast furnace. In the verification, first, normal blast furnace operation in which only pulverized coal is blown without using highly reactive coke is used as a standard. Based on this standard operating condition, the coke was switched to highly reactive coke, and the thermal preservation zone temperature drop due to the coke reaction rate improvement shown in FIG.

  In setting the conditions, the blending of highly reactive coke using biomass as a raw material with respect to the total amount of coke is 65 mass% and 80 mass%. Experiments have revealed that this formulation improves the JIS reaction rate of mixed coke from 30% to 35% and 41% of the standard condition. It is clear from Non-Patent Document 3 that when these mixed cokes are used in a blast furnace, the temperature of the heat preservation zone decreases from 1000 ° C. as a reference condition to 980 ° C. with 65 mass% of highly reactive coke and 960 ° C. with 80 mass%. It is. Table 7 is obtained by analyzing the operation of the blast furnace using the list model based on these conditions.

From Table 7, by blending highly reactive coke, the fuel ratio can be reduced by 6 kg / t in operation 1 and 11 kg / t in operation 2 compared to the standard conditions. FIG. 14 is obtained when the analysis results of the standard operation and the operation 2 are illustrated. As a result, the thermal storage zone temperature (T _R ) is lowered from 1000 ° C. to 960 ° C. by the reaction shown in the above formulas (a) and (b). As a result, the coordinates of X _W shift to a relatively high oxidation degree side. . As a result, under a constant shaft efficiency (a parameter indicating the degree of attainment of FeO to Fe reduction equilibrium), the gradient of the operating line (L) representing the reducing material ratio decreases and becomes L ₁ , leading to a fuel ratio of 11 kg / t. Further, the blast unit and the amount of generated gas at the top of the furnace are reduced by the reduction of the reducing material ratio, and X _A indicating the degree of oxidation of the furnace top gas shifts from L to L _{1, so that} it shifts to the high oxidation side. Table 7 is obtained based on such balance results.

  The mixing limit of highly reactive coke depends on the heat transfer characteristics of the blast furnace when the coke strength is constant and the air permeability in the blast furnace is maintained. The heat flow ratio (= enthalpy of solids in the heat storage zone / same gas) is a parameter that indicates the heat transfer characteristics of the blast furnace due to the relative reduction in the amount of gas generated from the tuyere when the reducing material ratio decreases due to the use of highly reactive coke. Defined by the ratio of enthalpy of Usually, in order to maintain the stable operation of the blast furnace, it is desirable to manage the heat flow ratio at 0.900 (−) or less. Table 7 shows 0.866 in operation 2, suggesting that the operation limit is almost approached from the viewpoint of heat transfer characteristics.

  From the above, when using a highly reactive coke made of woody biomass as a blast furnace, it was recognized that it is necessary to control the blending rate within 80 mass% in order to reduce the ratio of reducing materials. A particularly desirable blending ratio range is 50 to 80 mass%.

[Example 11]
The drying behavior was clarified by experiments on the premise that the biomass is dried by the Great method. The lower part of FIG. 15 is a biomass drying experiment apparatus using a pot grate furnace for sintering iron ore. In order to simulate the great drying furnace process 19 in the upper part of FIG. The heat insulating pot 20 is filled with woody biomass 21 having a predetermined moisture and particle size to a height of 30 cm. In this state, a dry gas 22 having a predetermined temperature and a predetermined flow rate is supplied from the upper part of the pot 20 under the condition that there is no drift, and exhausted from the lower part of the pot 20 through the blower 23. During the experiment, the temperature is continuously measured by the thermometer 24 on the bed, the thermometer 25 in the bed, and the thermometer 26 in the lower layer of the bed, and the experiment is interrupted every predetermined time, and the biomass of each part is collected. Moisture was measured. The drying characteristics of biomass are affected by biomass average particle size, bed passing gas flow rate, biomass layer thickness, drying temperature, initial moisture content, and the like. In this experiment, the influence of these operating factors on drying characteristics was experimentally clarified. Standard test for biomass drying in the Great Furnace system, assuming a biomass average particle size of 5 cm, a dry gas superficial velocity of 1.0 m / s, a biomass layer thickness of 30 cm, a drying temperature of 300 ° C., and a biomass initial moisture of 35 mass%. Was set.

(A) Influence of gas flow rate FIG. 16 shows the experimental results. It can be seen that the temperature rise of the gas is delayed because the latent heat of evaporation accompanying the drying is taken away from the gas side in the time region where the drying is actively progressing. Drying is completed in about 20 minutes at the standard superficial velocity of 1.0 m / s, but at 0.5 m / s, the biomass in the lower layer of the bed is dried only by about 60 mass%. When the flow rate is increased to 1.5 m / s, drying is completed in about 16 minutes. Accordingly, when the condition of the standard operation is the drying condition, the gas superficial velocity passing through the bed is desirably 1.0 m / s or more.

(B) Effect of drying gas temperature FIG. 17 shows the experimental results. From this point, when the drying temperature is 200 ° C. or less, the drying of the bed lower layer starts to be delayed. At 100 ° C., only about 50% of the drying proceeds, so that it is necessary to set a longer drying time. In addition, although drying progresses sufficiently at 300 degreeC, there exists a possibility of igniting biomass above this, Drying temperature is 100-300 degreeC, Desirably 200-300 degreeC is preferable.

(C) Influence of biomass initial moisture FIG. 18 shows the experimental results. As biomass moisture increases, the delay in drying becomes significant. Under the experimental conditions of the standard operation, the initial moisture limit is estimated to be 40 mass%. At 45 mass% or more, although the temperature rise in the lower layer of the bed is not sufficient, drying is achieved at about 90 mass%. When the initial moisture is 45 mass% or more, it is necessary to increase the gas flow rate or extend the drying time.

(D) Influence of biomass particle size FIG. 19 shows the experimental results. As the biomass particle size increases, the specific surface area of the biomass decreases and the heat transfer area decreases, resulting in a delay in the drying rate. Under standard operating conditions, when the biomass diameter is 10 cm, the drying time is delayed to nearly 26 minutes, but there is still room for drying conditions. For this reason, it is estimated that it is possible to select an operation in consideration of economics such as a decrease in drying temperature and a decrease in the drying gas superficial velocity. If the particle size is 10 cm or less, the operating conditions can be further afforded.

(E) Appropriate drying conditions using a great furnace The appropriate drying conditions can be set as follows from a drying experiment simulating a great furnace.
Dry gas superficial velocity: 0.5 to 1.5 m / s
Drying gas temperature: 100-300 ° C (However, it is necessary to extend the drying time at 100 ° C)
Biomass initial moisture: 40 mass% or less Biomass particle size: 10 cm or less (Drying conditions can be relaxed by reducing particle size)

DESCRIPTION OF SYMBOLS 1 Biomass chip tank 2 Drying process 3 Sinter cooler 4 Sintering machine 5 Dedicated storage tank 6 Crushing and grinding machine 7 Coal 8 Binder 9 Mixer 10 Molding process 11 Sieving process 12 Coal mixing tank 13 Coke oven 14 Blast furnace 15 Pig iron 16 Slag 17 Biomass storage tank 18 Pulverized coal 19 Great drying furnace process 20 Thermal insulation pot 21 Woody biomass 22 Drying gas 23 Blower 24 Thermometer on bed 25 Thermometer in bed 26 Thermometer in lower layer of bed

Claims (9)

  Heating and drying woody biomass, molding with coal to form a molded body, charging the molded body with coal into a coke oven and dry-distilling coke and charging into a blast furnace Blast furnace operation method using woody biomass as a raw material.   The blast furnace operation method using woody biomass as a raw material according to claim 1, wherein the woody biomass is dried so that the moisture content is 5 mass% or more and less than 30 mass%.   The method for operating a blast furnace using woody biomass as a raw material according to claim 1 or 2, wherein the woody biomass is dried using exhaust heat of 300 ° C or lower.   The dried woody biomass is pulverized, molded with coal to form a molded body, and the molded body is charged into a coke oven together with coal, and the charging ratio of the coke produced by dry distillation is charged into the blast furnace. A blast furnace operating method using woody biomass as a raw material according to any one of claims 1 to 3, wherein the amount is less than 80 mass% of the total amount of coke to be produced. Woody biomass is pulverized to a particle size of 3 mm or less, mixed with coal and molded. The volume of the molded body is 10 cm ³ or more and 50 cm ³ or less, and the bulk density is 0.8 g / cm ³ or more and 1.1 g / cm ^3. A blast furnace operating method using the woody biomass according to any one of claims 1 to 4 as a raw material.   The blast furnace operating method using the woody biomass as a raw material according to any one of claims 1 to 5, wherein the pulverized woody biomass is molded together with coal and a binder.   Coke production using woody biomass, characterized by heating and drying woody biomass, crushing it, molding it with coal to form a molded body, charging the molded body together with coal into a coke oven, and dry distillation Method. Woody biomass is pulverized to a particle size of 3 mm or less, mixed with coal and molded. The volume of the molded body is 10 cm ³ or more and 50 cm ³ or less, and the bulk density is 0.8 g / cm ³ or more and 1.1 g / cm ^3. 8. The method for producing coke using woody biomass as a raw material according to claim 7, characterized in that:   The method for producing coke using wood biomass as a raw material according to claim 7 or 8, wherein the pulverized wood biomass is molded together with coal and a binder.

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