JP6256701B2 - Method of injecting pulverized coal into the blast furnace - Google Patents

Description

  The present invention relates to a method of air transportation of pulverized coal, and in particular, in the air transportation (hereinafter also referred to as “air transportation”) in which pulverized coal is transported using a gas, the adhesion between particles and the transport amount of the pulverized coal By selecting pulverized coal that is considered suitable when paying attention to or by using it in a desirable blending ratio, a method for realizing stable pulverized coal in-pipe (pipe) air feeding, and in a blast furnace using this method We propose a method for injecting pulverized coal.

  Pulverized coal is one of solid fuels having a large specific surface area and excellent ignitability. This pulverized coal also has characteristics that it is easy to stop supply and can be ignited and extinguished in the same manner as liquid fuel or gaseous fuel when burned with a burner. Utilizing such characteristics, conventionally, in a blast furnace, this pulverized coal is practiced as a so-called pulverized coal injection operation in which part of the pulverized coal is blown into the furnace from the tuyere instead of coke as a reducing material. The operation of injecting pulverized coal into the blast furnace provides a significant cost reduction effect because pulverized coal is less expensive than blast furnace coke. Moreover, the injection of pulverized coal into the blast furnace leads to a reduction in the burden on the coke oven, which is a blast furnace coke manufacturing facility, and also contributes to the extension of the life of the coke oven. In recent blast furnace operations, technological development has progressed so that more pulverized coal can be injected, and at present, pulverized coal injection operation of about 120 kg / t-molten iron or more is also possible.

  By the way, when the pulverized coal is air-transported using a pipe and finally blown into a blast furnace through a tuyere, adhesion or blockage may occur in the pipe or the like. As one of the factors, the influence of the particle size distribution of pulverized coal has been pointed out. Therefore, conventionally, a method has been proposed in which the change over time in the particle size distribution of the pulverized coal is measured and managed so that the particle size distribution of the pulverized coal flowing in the piping to be aired is always properly maintained. In response to such demands, conventionally, a pulverized coal particle size measuring device, a pulverized coal production system, a blast furnace operation method, and the like for continuously measuring the particle size of pulverized coal have been developed. For example, a technique as disclosed in Patent Document 1 There is.

  In addition, as a control value of the particle size distribution performed in the prior art, the particle size distribution of the pulverized coal is based on the mass proportion of the particle size of −44 μm and the mass proportion of the particle size of −74 μm in the pulverized coal. Is measured, and the pulverization force of coal is adjusted so that the particle size distribution of pulverized coal of “45 mass% ≦ −44 μm ≦ 50 mass%, 60 mass% ≦ −74 μm” is obtained (Patent Document 1).

  In addition, it is suggested that the cohesiveness and adhesion inherent in each coal brand have an effect on the piping clogging phenomenon. Therefore, in order to evaluate the cohesiveness and adhesion of this pulverized coal, recently, the pulverized coal after drying is granulated, the granulated product is sieved for a certain period of time, and the residual rate on the sieve is measured. A method has been proposed (for example, Patent Document 2).

  In addition, an adjustment method has been proposed in which the fluidity index (rest angle, compression degree, spatula angle, sum of measurement indices of cohesion degree) of the pulverized coal used for preventing blockage of the pipe is greater than a reference value (for example, Patent Document 3).

JP 2013-43998 A Japanese Patent Laid-Open No. 4-65591 JP-A-4-224610

  By the way, in the technology disclosed in Patent Document 1, regardless of the coal brand, the particle size distribution is adjusted so that “45 mass% ≦ −44 μm ≦ 50 mass%, 60 mass% ≦ −74 μm” is satisfied to prevent blockage of the air supply piping. Are trying. However, even when the particle size distribution is adjusted as in this technique, there is a problem that when the coal brand is changed, the number of clogged pulverized coal feed pipes increases.

  In addition, the method disclosed in Patent Document 2, that is, the method of preparing pulverized coal for each coal brand, sieving the granulated material obtained at that time, and measuring the residual rate on the sieve is an actual method. There is a problem that this is not taken into account in spite of the fact that the particle size of the pulverized coal particles and the porosity between the particles have a large effect on the strength of the granulated product. Therefore, it is difficult to evaluate the inherent cohesiveness and adhesion of each coal brand only with the residual rate on the sieve.

  Further, the method disclosed in Patent Document 3 has the following problems. In other words, in the method of measuring the liquidity index for each coal brand, even if the pulverized coal of different brands has the same liquidity index (the sum of angles of repose, compression, spatula, and cohesion) Individual repose angles, compression degrees, spatula angles and cohesion indices may differ. Therefore, for example, when the angle of repose has a strong influence on the blockage of piping, when using pulverized coal with an extremely large angle of repose regardless of the flowability index, or when using small pulverized coal For example, it is considered that the pipe is often blocked.

  The present invention has been made in order to solve the above-described problems of the prior art, and by considering the interparticle adhesion between pulverized coal particles for each coal brand, the transport amount of pulverized coal, etc. It is an object of the present invention to propose a method for air-carrying pulverized coal, which is effective for preventing clogging in the piping for air-feeding coal, and a method for injecting pulverized coal into a blast furnace using this method.

  The present invention, as a method for solving the above-mentioned problems and realizing the above-mentioned object, provides the interparticle adhesion force and transport amount of the pulverized coal when air-transporting the pulverized coal from a plurality of pipes to the tuyere tuyeres. An effective method for preventing clogging in the pulverized coal pneumatic piping by selecting and using a suitable coal (pulverized coal) for pneumatic transportation when considering it is proposed.

(σ:引張破断強度(Ｎ／ｍ^２)、ε:空隙率(−)、Ｄ_Ｐ:調和平均径(ｍ)、Ｈ:２粒子間の付着力(Ｎ)) That is, the present invention is based on the following Rumpf equation as pulverized coal to be air-transported in a method of air-transporting in which one or more types of pulverized coal contained in a tank are transported using gas through a pipe. In this method, pulverized coal having an interparticle adhesion force value (H) of 3.26 × 10 ⁻⁷ N or less is used.

(sigma: Tensile strength at break ^{(N / m 2), ε} : voidage (-), D _P: the harmonic mean diameter (m), H: adhesion between the two particles (N))

(σ:引張破断強度(Ｎ／ｍ^２)、ε:空隙率(−)、Ｄ_Ｐ:調和平均径(ｍ)、Ｈ:２粒子間の付着力(Ｎ)) The present invention also relates to a method of blowing one kind of pulverized coal in a tank or two or more kinds of mixed pulverized coal into the furnace from the tuyeres of a blast furnace, and the following Rumpf A pulverized coal or mixed pulverized coal whose inter-particle adhesion value (H) calculated based on the equation is 3.26 × 10 ⁻⁷ N or less is air-transported and blown into a blast furnace from a tuyere through a blow pipe. We propose a method for injecting pulverized coal into a blast furnace.
Record

(sigma: Tensile strength at break ^{(N / m 2), ε} : voidage (-), D _P: the harmonic mean diameter (m), H: adhesion between the two particles (N))

In the present invention,
(1) The value of the adhesion between the particles of the pulverized coal is determined by compressing a powder layer of a kind of pulverized coal or a mixed pulverized coal composed of two or more types, and moving the compressed sample of the obtained pulverized coal powder layer up and down. Obtaining by measuring the maximum tensile rupture strength when the compressed sample of the pulverized coal powder layer is ruptured, pulled from the direction,
(2) A mixed pulverized coal obtained by selecting and combining a plurality of types of pulverized coal so that the interparticle adhesion value of the pulverized coal calculated using the Rumpf equation is 3.26 × 10 ⁻⁷ N or less. Air transport,
Furthermore,
(3) Pulverized coal blended so that the blockage index obtained by multiplying the adhesion force (N) between the particles by the amount of pulverized coal transport per hour (t / h) is 2.04 × 10 ⁻⁵ or less is air-flow transported And blow into the blast furnace from the tuyere through the blow pipe,
Is considered a more preferred embodiment.

  In the present invention, by adopting the configuration as described above, in consideration of the interparticle adhesion force of pulverized coal obtained for each coal brand, each pulverized coal does not cause aggregation due to adhesion. Select and use charcoal, or use any of these pulverized coals as mixed pulverized coal with low interparticle adhesion, or, if necessary, pulverized coal brands while considering transportation It becomes possible to appropriately adjust the blending conditions. As a result, according to the present invention, it is possible to prevent the pulverized coal from adhering and accumulating in the transport pipe and reliably prevent the pipe from being blocked.

  Further, according to the present invention, the prevention of clogging of the pneumatic piping can be achieved, so that a substantial increase in the amount of pulverized coal injected into the blast furnace can be achieved, and stable blast furnace pulverized coal injection can be achieved. Since it can be operated, blast furnace hot metal can be manufactured at low cost.

It is explanatory drawing for demonstrating the method of blowing pulverized coal in a blast furnace. It is explanatory drawing of the cell used with the measuring apparatus of the adhesion force between the particles of pulverized coal. It is a transition diagram of the number of closed pipes when pulverized coal A is blown into the blast furnace. It is a transition diagram of the number of closed pipes when pulverized coal B is blown into the blast furnace. It is the figure which showed the number of pipe | tube obstruction | occlusion of the daily average when pulverized coal A and pulverized coal B were injected in the blast furnace.

Hereinafter, a method for air-flow transportation of pulverized coal according to the present invention and a method for blowing pulverized coal into a blast furnace will be briefly described with reference to the drawings.
In FIG. 1, pulverized coal is blown into a blast furnace by storing coal 1 stocked in a yard in a coal hopper 2 and cutting out the coal 1 stored in the coal hopper 2 using a feeder 3. This is supplied to the pulverized coal production apparatus 4. The pulverized coal production apparatus 4 pulverizes the coal 1 and dries it to prepare pulverized coal 5 having a predetermined particle size.

  The pulverized coal 5 thus prepared is generally air-flowed to the large bag filter 7 through the main pipe 6. Next, the pulverized coal 5 collected by the large bag filter 7 is stored in the coalbin 8 and then accommodated in the blowing tank 9. The pulverized coal 5 in the blowing tank 9 is sent to the distributor 10, and further from the distributor 10 to a plurality of tuyere 13 at the lower part of the blast furnace 12 through the plurality of branch pipes 11 and the blow pipe 15. Distributed by air. Note that the pulverized coal 5 is injected from the blowing nozzle into the hot air supplied from the hot air furnace 14 to the blow pipe 15 of each tuyere 13 part, and is blown into the blast furnace 12 through the tuyere 13 together with the hot air to burn. To do.

  Thus, in order to blow the pulverized coal 5 into the furnace of the blast furnace 12, it is necessary to pass through several piping systems, valves, blowing devices, and the like. However, in today's pulverized coal injection blast furnace operation where a large amount of injection is required, the pulverized coal may adhere to the inside of the piping system or the like, and further, these piping may be blocked. When such pulverized coal is attached or blocked in a piping system or the like, normal blast furnace operation cannot be continued. In many cases, such adhesion and blockage in the piping system or the like often occur between the blowing tank 9 and the distributor 10, and this is because the pulverized coal transport speed in this portion is structurally smaller than that after the distributor 10. This is because the pulverized coal particles tend to adhere and agglomerate due to the setting.

  For example, if pulverized coal is blocked in one of the pipes, if this is blown into the blast furnace, there will be variations in the amount of pulverized coal blown in the circumferential direction of the furnace, which may lead to fluctuations in the hot metal components and furnace conditions. Cause. In particular, in the case of blast furnace operation with a large amount of pulverized coal injection, it is forced to reduce the wind and stop wind, which causes a significant problem such as reduced production.

  As described above, when pulverized coal adheres to the inner surface of the pipe or the pipe itself is blocked, a great loss is caused to the blast furnace operation. Therefore, when blowing pulverized coal into the blast furnace, the pulverized coal should flow smoothly without adhering to the piping system, that is, pipes, valves, holders, etc. Is strongly demanded.

  FIG. 2 is a diagram showing, in particular, the cell portion of the interparticle adhesion force measuring apparatus for calculating the adhesion force between particles of pulverized coal necessary for carrying out the method of the present invention, for example, between two particles. is there. As shown in this figure, the inter-particle adhesion measuring apparatus for pulverized coal is charged with the pulverized coal in a two-divided cell 19 composed of an upper cell 16, a lower cell 17, and a lower lid 18, and the two-divided cell. An upper lid 20 is placed on 19, tapped a predetermined number of times, and then compressed with a predetermined stress from above by the adhesive force measuring device to form a compressed sample comprising a powder layer 21. Then, the tensile rupture strength required for dividing the cell after applying the compressive stress, that is, the strength at the time of rupture when the compressed sample is pulled in the vertical direction is measured, and the tensile rupture strength is expressed by the following Rumpf equation: Substituting into (1), the adhesion force between the two particles is calculated.

(σ:引張破断強度(Ｎ／ｍ^２)、ε:空隙率(−)、Ｄ_Ｐ:調和平均径(ｍ)、Ｈ:２粒子間の付着力(Ｎ))

(sigma: Tensile strength at break ^{(N / m 2), ε} : voidage (-), D _P: the harmonic mean diameter (m), H: adhesion between the two particles (N))

  In addition, about the harmonic mean diameter of the pulverized coal in said (1) type | formula, the particle size distribution of the pulverized coal in the range of 17 nm-2500 micrometers is measured using the wet particle size distribution measuring apparatus by a laser diffraction scattering method, It calculates using the following formula | equation (2) from a volume ratio (vol%).

(Ｄ_Ｆ:調和平均径(ｍ)、ｄ:粒径(ｍ)、ｎ:体積割合(％))

( _DF : harmonic mean diameter (m), d: particle size (m), n: volume fraction (%))

  Moreover, about the porosity ε of the powder layer (compressed sample) of the pulverized coal in the above formula (1), the bulk density obtained from the height of the powder layer measured by an adhesion force measuring device and the pulverized coal particles It calculates using the particle density of. Here, the height of the powder layer is the height of the pulverized coal powder layer (compressed sample) after the compressive stress is applied by the adhesive force measuring device, and the particle density is measured using the particle density measuring device. The

  Now, the present invention calculates the interparticle adhesion force (H) of pulverized coal for each coal brand, selects one or more types of pulverized coal having a small adhesion force, and further determines the particle size and porosity. Is also a method of preventing the clogging of the pipe by preventing the adhesion and aggregation of the pulverized coal particles in the transport pipe by adjusting the formulation in consideration of the above.

  In addition, since the aggregation of the pulverized coal particles in the transport pipe is also affected by the amount of pulverized coal transport, it is more preferable to add pulverized coal having a low interparticle adhesion force while also considering the amount of pulverized coal transport. .

For example, coal A and coal B having the chemical compositions shown in Table 1 are dried in a N ₂ atmosphere and then pulverized by a pulverizer to form pulverized coal, and each particle size distribution is measured with a wet particle size distribution measuring device. When the harmonic mean diameter was calculated, pulverized coal A was 1.4 × 10 ⁻⁵ m, and pulverized coal B was 1.7 × 10 ⁻⁵ m.

And in order to calculate the adhesion between the particles of the pulverized coals A and B, first, by using the measuring apparatus shown in FIG. It was measured. As measurement conditions, first, each pulverized coal was charged into a two-part cell 19 having an inner diameter of 20 mm to the height of the cell, and the upper lid 20 was placed and tapped up and down about 100 times. Thereafter, the pulverized coal powder layer in the cell was compressed at a rate of 0.1 mm / sec while maintaining the temperature at 25 ° C., and the compressed state was maintained for 60 seconds when the compressive stress reached 4.0 MPa. Then, the upper cell 16 and the lower cell 17 were pulled in the vertical direction at a speed of 0.1 mm / sec, and the tensile breaking strength σ required for division was measured. As a result, the pulverized coal A, tensile strength at break of the pulverized coal B was respectively ^{4300N / m 2, 1750N / m} 2. Further, the particle density ρ ₂ of pulverized coal A and pulverized coal B was measured in advance with a particle density measuring device.

The particle density of the pulverized coal A measured was 1461.9 kg / m ³ , and the particle density of the pulverized coal B was 1404.8 kg / m ³ . From the volume calculated by measuring the height of the pulverized coal powder layer 21 when a stress of 4.0 MPa is applied to the pulverized coal pulverized coal layer 21 using an interparticle adhesion measuring device and the mass of the pulverized coal input, the pulverized coal The bulk density ρ ₁ of the powder layer was calculated. The porosity ε was calculated from the particle density ρ ₂ and the bulk density ρ ₁ using the following formula (3). The porosity of pulverized coal A and pulverized coal B was 0.325 and 0.330, respectively.

(ε：空隙率(−)、ρ_１：嵩密度(ｋｇ／ｍ^３)、ρ_２：粒子密度（ｋｇ／ｍ^３）)

(ε: porosity (−), ρ ₁ : bulk density (kg / m ³ ), ρ ₂ : particle density (kg / m ³ ))

Therefore, the inter-particle adhesion force of pulverized coal by substituting the measured tensile rupture strength (σ), harmonic mean diameter (m), and porosity (ε) of the pulverized coal powder layer 21 into the Rumpf equation (1). As a result, the adhesion between particles of pulverized coal A and pulverized coal B is 4.25 × 10 ⁻⁷ N and 2.60 × 10 ⁻⁷ N, respectively. The result was small.

  Here, the adhesion / aggregation force between particles is (1) Van der Waals force (intermolecular force between solid particles), (2) charged adhesion force, and (3) moisture in the atmosphere is adsorbed on the particles. (4) Mechanical entanglement between particles due to the surface shape of the particles due to surface tension and capillary negative pressure generated by the liquid cross-linking, and the total shape of these forces is the sum of these forces. It is the interparticle adhesion force of pulverized coal calculated using Equation (1). That is, the interparticle adhesion force calculated using the Rumpf equation (1) is considered to be a numerical value that affects the adhesion and aggregation of pulverized coal particles. Moreover, the interparticle adhesion of pulverized coal varies depending on the coal brand.

Particularly in the present invention, as the pulverized coal to be air-transported in the pipe, the mixed pulverized coal obtained by selecting one or more of the pulverized coal has a predetermined value and a range of adhesion between these particles. It is important to use it. According to the knowledge of the inventors, the value (H) of interparticle adhesion calculated using the Rumpf equation of pulverized coal or mixed pulverized coal to be transported by airflow is 3.26 × 10 ⁻⁷ N or less. At one time, it was found that the result that the blockage of the airflow transportation pipe was eliminated to the extent that it hardly caused a problem in the operation of the blast furnace, that is, once a day or less.

That is, in the method of injecting pulverized coal into the blast furnace, if the blockage in the air flow transportation pipe is less than once a day, the blast furnace operation can be stably performed and the heat fluctuation in the furnace can be prevented. Is possible. If heat fluctuation occurs, an operation action is required to stabilize the heat by increasing the amount of expensive coke compared to pulverized coal, leading to an increase in hot metal costs.
Therefore, in the present invention, the use of pulverized coal (including mixed pulverized coal) exhibiting an interparticle adhesion force (H) ≦ 3.26 × 10 ⁻⁷ N with a blocking rate of once or less per day. It was.

[Example 1]
In this example, in order to confirm the influence of the adhesion force within the pulverized coal particles calculated by the Rumpf equation (1), the pulverized coal A and the pulverized coal B shown in Table 1 were replaced with 40 tuyere. In the blast furnace having an internal volume of 5153 m ³ , the operation of blowing pulverized coal into the blast furnace at a target 10000 t / day hot metal production rate and a pulverized coal ratio of [150 kg / t-hot metal] was carried out for 7 days. If the pulverized coal transportation piping toward each tuyere is blocked, the actual pulverized coal ratio is changed without changing the amount of pulverized coal injection per tuyere so that the load of the pulverized coal transportation piping does not change. The minute coke ratio was adjusted. The management value of the particle size distribution of the pulverized coal to be blown was set to “45 mass% ≦ −44 μm ≦ 50 mass%, 60 mass% ≦ −74 μm”.

Changes in the number of closed transportation pipes for 7 days when pulverized coal A and pulverized coal B are used are shown in FIGS. 3 and 4, respectively. Further, FIG. 5 shows the daily average number of closed transportation pipes. From the results of FIGS. 3, 4 and 5, pulverized coal B (H = 2.60 × 10 ⁻⁷ N) is selected and pulverized, and this is used for pulverized coal injection operation into a blast furnace. Piping blockage could be reliably prevented.

[Example 2]
In this example, an operation was performed in which pulverized coal obtained by mixing and pulverizing a plurality of brands of coal was blown into a blast furnace. That is, pulverized coal A and pulverized coal B are mixed at different ratios, and the mixed pulverized coal is mixed in a blast furnace having an inner volume of 5153 m ³ having 40 tuyere and a target amount of hot metal production of 10,000 t / day, [150 kg / T-hot metal], the operation of blowing from the tuyere was carried out for 7 days. When the pulverized coal transportation pipes of each tuyere are blocked, the actual pulverized coal ratio is changed without changing the amount of pulverized coal injection per tuyere so that the load of the pulverized coal transportation pipes does not change. The coke ratio was adjusted. The control value of the particle size distribution of the pulverized coal to be blown was set to “45 mass% ≦ −44 μm ≦ 50 mass%, 60 mass% ≦ −74 μm”.

Table 2 shows the average number of closed transport pipes per day when the mixing ratio of pulverized coal A and pulverized coal B is changed. Moreover, the weight average of each adhesion force of pulverized coal A and pulverized coal B was used for the adhesive force between two particles of pulverized coal A which changed and changed the ratio of pulverized coal A and pulverized coal B. From the results of the test, the average pipe clogging per day under the conditions of blending pulverized coal A of 40 mass% or less and pulverized coal B of 60 mass% or more (adhesion between particles is 3.26 × 10 ⁻⁷ N or less) The number was 1.0 or less, and it was found that blockage of the transportation piping can be effectively prevented.

In this example, in order to operate at a target 10000 t / day hot metal production rate and a pulverized coal ratio of [150 kg / t-hot metal], the pulverized coal transport rate was blown to 62.5 t / h. However, when the transport amount is changed, it is considered that the frequency of occurrence of pipe clogging also changes, so that the condition of adhesive force is such that the number of pipe clogging per day is 1.0 or less. It is considered necessary to change the blending ratio of pulverized coal A and pulverized coal B. Therefore, this time, attention was focused on an index obtained by multiplying the adhesion force (N) of pulverized coal particles and the transport amount of pulverized coal (t / h). Table 3 shows the clogging index calculated when the index was taken as the clogging index, and the operation was performed at a target 10000 t / day hot metal production volume and a pulverized coal ratio of [150 kg / t-hot metal]. From Table 3, when considering the transport amount of pulverized coal, when the clogging index is 2.04 × 10 ⁻⁵ or less, the average number of clogged pipes per day is 1.0 or less, and the clogging of pipes It can be prevented.

[Example 3]
Next, when the pulverized coal adhesion force and pulverized coal transport amount are such that the clogging index is 2.04 × 10 ⁻⁵ or less, the number of clogged pipes per day is 1.0 or less, and the target is 10,000 t. Per day for 7 days. The pulverized coal ratio is [120 kg / t-hot metal], [140 kg / t-hot metal], [160 kg / t-hot metal], [180 kg / t-hot metal], and each pulverized coal transport amount is 50.0 t / h, Since it is 58.3 t / h, 66.7 t / h, and 75.0 t / h, the target adhesion force of the pulverized coal particles is 4.08 × 10 ⁻⁷ N, 3.49 × 10 ⁻⁷ N, and 3. The blending conditions of pulverized coal A and pulverized coal B were determined so as to be 06 × 10 ⁻⁷ N and 2.72 × 10 ⁻⁷ N. Table 4 shows the operation results at this time. From Table 4, the average number of closed pipes per day is reduced to 1.0 or less by changing the blending ratio so that the pulverized coal adhesion becomes 2.04 × 10 ⁻⁵ or less from Table 4. Effective. It is thought that it is possible to prevent obstructing piping.

In addition, as shown in Table 5, pulverized coal produced only from coal A into the blast furnace in the operation under the condition that the blockage index is 2.04 × 10 ⁻⁵ or less and the pulverized coal ratio of [150 kg / t-molten metal]. Compared with Table 6 of the operation result in which A was blown, the coke ratio can be suppressed in the operation where the blockage index is 2.04 × 10 ⁻⁵ or less and the average number of closed pipes per day is 1.0 or less. It was proved that it was possible to produce low-cost blast furnace hot metal by substantially increasing the amount of pulverized coal injection.

  The technique for gas transport of pulverized coal according to the present invention can be applied as a gas transport technique for piping of the same kind of powder and granules other than pulverized coal, in addition to a method for blowing pulverized powder into a blast furnace.

1 Coal stocked in 1 yard 2 Coal hopper 3 Feeder 4 Pulverized coal production equipment (conventional example)
5 Pulverized coal 6 Main pipe 7 Large bag filter 8 Coalbin 9 Blowing tank 10 Distributor 11 Branch pipe 12 Blast furnace 13 Tuyere 14 Hot air furnace 15 Blow pipe 16 Upper cell 17 Lower cell 18 Lower lid 19 Two-divided cell 20 Upper lid 21 Powder layer

Claims (2)

In a method in which one kind of pulverized coal in a tank or two or more kinds of mixed pulverized coal is blown into the furnace from the tuyere's tuyeres, the pulverized coal to be air-transported and the mixed pulverized coal are based on the following Rumpf equation (1). The pulverized coal and mixed pulverized coal whose adhering force value (H) between the two particles is 3.26 × 10 ⁻⁷ N or less and transported with the pulverized coal per hour in the adhering force (H) between the two particles. To the blast furnace, which is blended so that the blockage index multiplied by the amount (t / h) is 2.04 × 10 ⁻⁵ or less, transported by airflow, and blown into the blast furnace from the tuyere through the blow pipe. Of pulverized coal .
Record

(sigma: Tensile strength at break ^{(N / m 2), ε} : voidage (-), D _P: the harmonic mean diameter (m), H: adhesion between the two particles (N)) The value of the adhesion between the particles of the pulverized coal is determined by compressing a powder layer of a kind of pulverized coal or a mixture of two or more types of pulverized coal, and pulling the compressed sample of the obtained pulverized coal powder layer from above and below. The method for injecting pulverized coal into a blast furnace according to claim 1, wherein the maximum tensile rupture strength when the compressed sample of the pulverized coal powder layer is ruptured is measured.

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