JP2011148929A - Method for estimating the amount of raised dust of coal to be charged, method for estimating the thickness of deposited carbon, and method for operating chamber-type coke oven - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably operate a coke oven by precisely estimating the amount of raised dust in consideration of the impact and raising dust effect of fine powder and properly estimating the thickness of deposited carbon based on the estimate. <P>SOLUTION: Raw material coal is classified into fine powder coal and coarse particle coal. The fine powder coal is agglomerated into agglomerated coal. The agglomerated coal and the coarse particle coal are charged into a coke oven as a coal to be charged for dry distillation. At this time, the amount Hdst (mass%) of raised dust which is raised when coal is charged is estimated by the following formula (1) and the thickness of deposited carbon is properly estimated based on the estimate: Hdst=k1[HGI]+k2+[Gv]+k3[Dp]+k4[M]+k5[OL]+k6[Mrf]+k7[Rsep]+k8[Mcp]+k9 (1), wherein HGI: grindability index of coal, Gv: gas flow rate (m/s), Dp: fineness number of coal, M: moisture content of coal (mass%), OL: oil addition rate to coal (mass%), Mrf: proportion of fine powder in coarse particle coal (mass%), Rsep: classification rate (mass%), Mcp: proportion of 0.3-1 mm in coal to be charged (mass%), and k1-k9: coefficient determined by multiple linear regression analysis. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a method for estimating the amount of dust generated from charging coal in the operation of a chamber coke oven, a method for estimating the thickness of attached carbon, and a method for operating a chamber coke oven based on the estimation method.

  In the process of carbonizing coal in a coke oven carbonization chamber to produce coke, carbonization gas (hydrocarbon compound) generated from coal is pyrolyzed to produce carbon, and the furnace wall and top space of the carbonization chamber, Furthermore, it adheres to the riser base. Increasing the amount of carbon adhering to the furnace wall and top space of the carbonization chamber will increase coke extrusion resistance during coke extrusion after coal carbonization, resulting in operational failures and economic losses such as furnace damage and coke clogging. Will be invited.

  In addition, if the carbon adhering amount at the base of the riser is excessively increased and the riser is clogged during coal dry distillation, the flow of coke oven dry distillation gas to the gas refining process is interrupted. Or carbonization gas leaks from the coke oven inlet and the furnace lid, which has a significant impact on the environment and energy.

  Therefore, various countermeasures against carbon adhering to the riser base or adhering carbon have been proposed so far from the viewpoint of (1) not adhering carbon or (2) removing adhering carbon. ((1) viewpoint: Patent Documents 1 to 5, see, (2) viewpoint: Patent Documents 6 to 10).

  All of these measures are expected to be effective in terms of carbon adhesion suppression or carbon removal, but when carbonization of pyrolysis gas proceeds significantly faster, carbon adhesion suppression Or removal of adhering carbon may not be in time, and the riser may be blocked.

  In view of this, the present inventors have proposed a method for estimating the deposited carbon thickness and a method for operating a coke oven using the estimated method in order to solve the problem of clogging of the riser due to carbon adhesion (see Patent Document 11). .

  The above estimation method takes into consideration the moisture and volatile content of conventional coal, the temperature of the furnace top space (including the riser base), dust generation during charging, and the volume of the furnace top space, This is to estimate the deposited carbon thickness. And according to the said operation method, since obstruction | occlusion of a riser base part can be avoided and operation is stabilized, a big economic and technical effect can be acquired.

  However, in order to classify coal into pulverized coal and coarse coal, and reduce the amount of dust generated from pulverized coal, the pulverized coal is agglomerated to form agglomerated coal, which is then mixed with coarse coal and carbonized. In the case of a method for producing coke charged into a chamber (for example, see Patent Document 12), in particular, when the use ratio of agglomerated coal is increased, the actually measured adhered carbon is larger than the deposited carbon thickness estimated by the estimation method of Patent Document 11. It became clear that the estimated value and the measured value differed as the thickness increased.

  In this way, when the estimated value is less than the actual measured value, even if the estimated value predicts that no blockage will occur during dry distillation, the riser will be blocked in actual operation. So it is not preferable. Therefore, in place of the estimation method of Patent Document 11, there is a need for an estimation method of the attached carbon thickness at the riser base that can be applied even when agglomerated coal and coarse coal are mixed and used.

Japanese Patent Laid-Open No. 05-14136 Japanese Utility Model Publication No. 60-82442 Japanese Patent Laid-Open No. 06-271864 JP-A-53-72002 JP 09-263663 A JP 58-120686 A Japanese Patent Laid-Open No. 05-1287 Japanese Patent Laid-Open No. 05-271661 Japanese Patent Laid-Open No. 06-322373 JP 07-247482 A JP 2002-173683 A JP 2006-283008 A

CAMP-ISIJ, vol.20, 2007, p.875

  When coke is produced by classifying raw coal into pulverized coal and coarse coal, agglomerating pulverized coal into agglomerated coal, and then mixing this agglomerated coal and coarse coal, coke is used. When the ratio is large, the estimated value of the attached carbon thickness estimated by the estimation method of Patent Document 11 deviates from the actually measured value of the attached carbon thickness. This is due to the following reason.

  (I) In the process of classifying pulverized coal into pulverized coal and coarse coal, it is extremely difficult to completely separate fine coal particles of 0.3 mm or less that greatly affect the carbon adhesion amount of the coke oven from coarse coal. The pulverized particles remain in the coarse coal. (Ii) After the pulverized coal is agglomerated into agglomerated coal, the agglomerated coal is mixed with the coarse coal and charged coal. (Ii-1) The fine powder remaining in the coarse coal (hereinafter also referred to as “residual fine particles”) is separated from the coarse coal when it is charged into the carbonization chamber. The amount of dust generation increases due to scattering (hereinafter referred to as “impact / dust generation effect of fine powder. This effect will be described in detail later), (ii-2) As a result, during the carbonization in the coke oven. The amount of produced carbon increases (see Non-Patent Document 1).

  Therefore, the present invention classifies the raw coal into pulverized coal and coarse coal, agglomerates the pulverized coal into agglomerated coal, and then mixes the agglomerated coal and coarse coal and charges them into the coke oven. Then, when carbonizing coke, considering the impact and dust generation effect of fine powder, accurately estimate the dust generation amount of the charging coal, and properly estimate the attached carbon thickness based on the estimated value, Furthermore, it makes it a subject to operate a room-type coke oven stably based on this estimated value.

  On the premise of the estimation formula for the dust generation amount of the charging coal proposed in Patent Document 11, the present inventors classify the raw coal into pulverized coal and coarse coal, agglomerate the pulverized coal, Then, when the agglomerated coal and the coarse coal are charged into a chamber coke oven as dry coal and dry-distilled, the amount of dust generated taking into account the impact and dusting effect of fine powder caused by the agglomerated coal The estimation formula of As a result, the estimation formula Hdst defined by the following formula (1) was created.

Hdst = k1 [HGI] + k2 [Gv] + k3 [Dp] + k4 [M] + k5 [OL]
+ K6 [Mrf] + k7 [Rsep] + k8 [Mcp] + k9 (k1 to k9: coefficients determined by multiple regression analysis) (1)

  The above formula (1) is based on the estimation formula H proposed in Patent Document 11 in consideration of the impact and dust generation effect of fine powder due to the agglomerated coal, Mrf: the proportion of fine powder in coarse coal (mass%) ), Rsep: classification rate (mass%), and Mcp: a new term relating to the proportion (mass%) of coal particles of 0.3 to 1 mm in the charged coal is added by linear linear combination, To do.

  The present invention has been made on the basis of the above formula (1) in consideration of the impact and dust generation effect of fine powder, and the gist thereof is as follows.

(1) Classifying raw coal into pulverized coal and coarse coal, agglomerating pulverized coal into agglomerated coal, and then loading the agglomerated coal and coarse coal into a chamber coke oven. A method for estimating the amount of dust generated by charging coal, characterized in that the amount of dust Hdst (mass%) generated from the charged coal during charging is estimated by the following equation (1). .
Hdst = k1 [HGI] + k2 [Gv] + k3 [Dp] + k4 [M] + k5 [OL]
+ K6 [Mrf] + k7 [Rsep] + k8 [Mcp] + k9 (1)
HGI: Coal grindability index Gv: Gas flow rate (m / s)
Dp: Coal particle size index M: Coal moisture content (% by mass)
OL: Oil addition rate to coal (mass%)
Mrf: Ratio of fine powder in coarse coal (mass%)
Rsep: Classification rate (mass%)
Mcp: Ratio of coal particles of 0.3 to 1 mm in charging coal (mass%)
k1 to k9: Coefficients determined by multiple regression analysis

  (2) After classifying the raw coal into pulverized coal and coarse coal and agglomerating the pulverized coal into agglomerated coal, the coal and the coarse coal are charged into the chamber coke oven. When carbonizing and carbonizing, the horizontal thickness of carbon adhering to the inner surface of the riser during one cycle of carbonization: Doil-space-fine (mm / day) is estimated by the following formula (2). A method for estimating the thickness of attached carbon.

Doil-space-fine
= 64.5 x Exp (k10 x OL + k11 x W + k12-7950 / T)
× VM × (1-0.0476 × M)
× Exp {(k13 + k14 × Hdst) × (1-ξ (τ))} (2)
Hdst = k1 [HGI] + k2 [Gv] + k3 [Dp] + k4 [M] + k5 [OL]
+ K6 [Mrf] + k7 [Rsep] + k8 [Mcp] + k9
OL: Oil addition rate to coal (mass%)
W: Coal charge into the carbonization chamber (ton)
T: Temperature of the riser base (K)
VM: Coal volatile matter (mass%)
M: Moisture content of coal (% by mass)
Hdst: Coal dust generation (% by mass)
ξ (τ): Correction factor τ: Elapsed time after charging coal (h)
HGI: Coal grindability index Gv: Gas flow rate (m / s)
Dp: Particle size index of coal Mrf: Ratio of fine powder in coarse coal (mass%)
Rsep: Classification rate (mass%)
Mcp: Ratio of coal particles of 0.3 to 1 mm in charging coal (mass%)
k1 to k14: Coefficient

  (3) After classifying the raw coal into pulverized coal and coarse coal, agglomerating the pulverized coal into agglomerated coal, and then loading the agglomerated coal and the coarse coal into the chamber coke oven as charging coal. When carbonizing and carbonizing, the horizontal thickness of carbon adhering to the inner surface of the riser during one cycle of carbonization: Doil-space-fine (mm / day) is estimated by the following formula (3). A method for estimating the thickness of attached carbon.

Doil-space-fine
= 64.5 × Σ [Exp (k10 × OL + k11 × W + k12-7950 / Tm (Δτ))
× VM × (1-0.0476 × M)
× Exp {(k13 + k14 × Hdst) × (1-ξm (Δτ))}] (3)
Hdst = k1 [HGI] + k2 [Gv] + k3 [Dp] + k4 [M] + k5 [OL]
+ K6 [Mrf] + k7 [Rsep] + k8 [Mcp] + k9
OL: Oil addition rate to coal (mass%)
W: Coal charge into the carbonization chamber (ton)
Tm: Average value of temperature in minute time Δτ (K)
VM: Coal volatile matter (mass%)
M: Moisture content of coal (% by mass)
Hdst: Coal dust generation (% by mass)
ξm (τ): Average value of correction coefficient (−) in minute time Δτ
Δτ: Minute time (relative value for one cycle of carbonization)
HGI: Coal grindability index Gv: Gas flow rate (m / s)
Dp: Particle size index of coal Mrf: Ratio of fine powder in coarse coal (mass%)
Rsep: Classification rate (mass%)
Mcp: Ratio of coal particles of 0.3 to 1 mm in charging coal (mass%)
k1 to k14: Coefficient

  (4) Based on the adhesion carbon thickness estimated by the method for estimating the adhesion carbon thickness described in (2) above, the carbon on the inner surface of the riser pipe is adjusted in advance by adjusting the properties and / or operating conditions of the charging coal. A method for operating a coke oven, characterized by suppressing adhesion of the riser and preventing the riser from being blocked.

  (5) Based on the adhesion carbon thickness estimated by the method for estimating the adhesion carbon thickness described in (3) above, during the operation, the properties and / or operation conditions of the charging coal are adjusted, and the inner surface of the riser pipe is adjusted. A method for operating a coke oven, characterized by suppressing carbon adhesion and preventing the riser from being blocked.

  According to the present invention, when mixed agglomerate and coarse coal are used as charging coal, the raw coal is classified into pulverized coal and coarse coal, and the pulverized coal is agglomerated and agglomerated. Then, when charging the carbonized coal and the coarse coal into the chamber coke oven as dry coal and dry distillation, the dust generation amount of the charged coal is accurately estimated, and based on the estimated value. Adhering carbon thickness can be estimated appropriately, and the coke oven can be stably operated based on the estimated value.

It is a figure which shows the correlation of the estimated dust generation amount (mass%) by the estimation formula H (patent document 11) and the measured dust generation amount (mass%) in the case where the agglomerated coal which consists of pulverized coal is not used as charging coal. . Correlation between estimated dust generation (mass%) and estimated dust generation (mass%) according to estimation formula H (Patent Document 11) in the case of dry distillation of mixed coal of coarse coal and coarse coal consisting of pulverized coal FIG. It is a figure which shows the one aspect | mode of the pretreatment process which manufactures the mixed charging coal of the agglomerated coal and coarse-grained coal which consist of pulverized coal. It is a figure which shows the aspect of the test apparatus which measures the amount of dust generation. It is a figure which shows the dust generation mechanism at the time of charging charcoal charging. (A) shows a dust generation mechanism in the case of sample B of coarse coal (residual fine particles of 0.3 mm or less: including 19% by mass), and (b) coarse coal B: 75% by mass + Agglomerated coal: A dust generation mechanism in the case of 25% by mass of sample C is shown. It is a figure which shows the result of investigating how much dust generation amount changes with the presence or absence of agglomerated coal by making the quantity of the residual fine powder particle | grains contained in charging coal into the same. It is a figure which shows the particle size distribution before the fall of the sample measured with the test apparatus shown in FIG. 4, and the particle size distribution after the drop. (A) shows the particle size distribution of sample D (see Table 1) of coarse coal (residual fine particles of 0.3 mm or less, including less than 1% by mass), (b) shows “coarse of sample D The particle size distribution of Sample E (see Table 1) of “granulated coal: 75 mass% + agglomerated coal: 25 mass%” is shown. It is a figure which shows an example of the result of having determined Hdst and having compared the estimated value of dust generation amount, and the measured value. It is a figure which shows the growth rate (kg / m < ² > / h) of the adhesion carbon measured about 835 degreeC and 950 degreeC about the sample A, C, and E shown in Table 1. FIG. (A) shows the growth rate of attached carbon at 835 ° C., and (b) shows the growth rate of attached carbon at 950 ° C. It is a figure which shows the relationship between the dust generation amount (mass%) at the time of charging charcoal charging, and the growth rate (kg / m < ² > / h) of attached carbon. It is a figure which shows the procedure which estimates the amount of adhesion carbon. It is a figure which shows the correlation of the estimated adhesion carbon amount (kg / m < ² > / ch) and the measurement estimated adhesion carbon amount (kg / m < ² > / ch). It is a figure which contrasts the obstruction | occlusion rate of a riser base part with the conventional obstruction | occlusion rate. It is a figure which shows the outline of the test apparatus for evaluating the growth rate of the adhesion carbon in this invention.

The present invention will be described in detail. In the patent document 11, the present inventors proposed the estimation formula H of the dust generation amount.
H = k1 ′ [HGI] + k2 ′ [Gv] + k3 ′ [Dp] + k4 ′ [M] + k5 ′ [OL]
k1 'to k5' are coefficients determined by multiple regression analysis

  HGI is a pulverization index of coal, and usually a hard glove index (an index according to a test method for coal according to JIS M8801) is used. Gv is a gas flow rate (m / s), and the gas flow rate measured by the dust concentration measuring method in the exhaust gas of JIS Z8808 is usually used.

  Dp is the particle size index of coal, and the mass% under the sieve when measured using a sieve with an arbitrary opening diameter is used. M is the moisture content (mass%) of coal, and the moisture content measured by the industrial analysis method of JIS M8812 is usually used. OL is an oil addition rate (mass%) to coal. k1 ′ to k5 ′ are coefficients determined by multiple regression analysis.

  FIG. 1 shows the correlation between the estimated dust generation amount (% by mass) and the actually measured dust generation amount (% by mass) according to the estimation formula H when agglomerated coal made of pulverized coal is not used as charging coal. In addition, the estimated dust generation amount (mass%) by the estimation formula H was obtained by the estimation method of Patent Document 11. When agglomerated coal is not used as charging coal, the estimated dust generation (mass%) and the measured dust generation (mass%) agree very well.

  However, in the case where charging coal comprising a mixture of agglomerated coal and coarse coal is charged, when the dust generation amount is estimated by the estimation formula H, as shown in FIG. 2, the estimated dust generation amount and the actual dust generation amount are shown. (% By mass) is not correlated. This is due to the fact that the estimation formula H does not take into account the impact / dust generation effect of fine powder resulting from agglomerates that cannot be ignored.

  In FIG. 3, the one aspect | mode of the pre-processing process which manufactures the mixed charging coal of the agglomerated coal and coarse-grained coal which consist of pulverized coal is shown.

  The pulverized coal 1 is charged into a fluidized bed drying classifier 2 and heated gas 3 is ejected from the bottom of the fluidized bed drying classifier 2 to classify into coarse coal 4 and fine powder 5 while drying the coal 1 while flowing. To do. At this time, the classification points of the coarse coal 4 and the fine powder 5 are appropriately determined depending on the operating conditions of the coke oven, but generally, the classification is about 0.5 mm from the viewpoint of suppressing dust generation during the transport of the dry coal. At this point, it is classified into coarse coal 4 and fine powder 5.

  In this embodiment, the drying and classification of the coal are simultaneously performed using the fluidized bed drying classification 2. However, after the coal is dried using the dryer, the pulverized coal and the coarse coal are subsequently used using the classifier. You may classify them.

  The fine powder 5 after classification is transported to the molding machine 6 as it is and molded into the agglomerated coal 7. This agglomerated coal 7 is mixed with the coarse coal 4 and charged into the coke oven carbonization chamber 8 as charged coal.

  By using the classified fine powder as agglomerated coal, it is possible to suppress the generation of dust to a considerable extent as compared with the case where dry coal is charged without classification and charged into the coke oven carbonization chamber.

  However, fine powder particles adhere to the accompanied coarse coal particles or are discharged from the classifier 2 in the accompanying state, mixed with the agglomerated coal as it is, and the residual fine particles charged into the coke oven carbonization chamber. There are many.

  These residual fine particles are the cause of dust generation due to the impact and dust generation effect of the agglomerated coal when the agglomerated coal and coarse coal made of pulverized coal are charged into the coke oven carbonization chamber as the charged coal. Presumed. As shown in FIG. 2, it is confirmed in the next test that the estimated dust generation amount and the actually measured dust generation amount (mass%) are not correlated when the estimation method of Patent Document 11 is used. did.

  FIG. 4 shows the test apparatus. A sample container 10 installed on the upper part of an acrylic pipe (φ125 × height 2000 mm) 14 is filled with a sample (mixed coal of agglomerated coal and coarse coal) 9 having a predetermined particle size and amount (for example, 1 kg). .

  A suction machine (not shown) connected to the suction machine connection port 12 is operated, and the acrylic pipe 14 is passed through the air blowing port 15 at a predetermined flow rate (for example, 3.7 m / s equivalent to an actual furnace). With the air 17 in the upward direction, the upper slide gate 11 is opened, and the sample 9 is dropped by gravity. Here, the suction flow rate is set based on the suction gas flow rate in the carbonization chamber when charging coal into the actual furnace.

  One minute after opening the upper slide gate 11, the operation of the suction device is stopped, and the lower slide gate 11 is opened and the coal sample deposited on the lower slide gate 11 is accommodated in the sample receiver 16. And measure its mass.

The dust generation amount (mass) and the dust generation rate (mass%) are obtained as follows.
Dust generation amount (mass) = Mass of fine powder taken out of acrylic pipe 14 = (Mass of sample filled in sample container 10) − (Mass of sample accommodated in sample receiver 16)
Dust generation rate (mass%) = [{(mass of sample filled in sample container 10) − (mass of sample contained in sample receiver 16)} / (mass of sample filled in sample container 10)] × 100

  Since the sample is charged coal made of a mixture of agglomerated coal and coarse coal, the dust generation amount is a dust generation amount including the impact and dust generation effect of fine powder resulting from the agglomeration coal. In addition, the suction flow rate of the suction machine is set to the suction gas flow rate in the carbonization chamber when charging the charging coal into the actual furnace, so the dust generation amount is a mixed charging coal of coarse coal and coarse coal. It corresponds to the amount of dust generated when is charged into an actual furnace.

  The present inventors prepared samples A to F made of six kinds of charged coals having different properties, and measured the dust generation rate (mass%) with the test apparatus shown in FIG. The results are shown in Table 1.

  From Table 1, the following can be understood.

  (O) From the comparison between the dust generation rate of sample A and (a1) the dust generation rates of sample B and sample C, when the amount of residual fine particles decreases, the dust generation rate also decreases, and (a2) sample D From the comparison with the dust generation rate of sample E, when the amount of residual fine particles is almost completely removed, the dust generation rate is greatly reduced.

  (P) When sample B and sample C are compared, sample C has a small dust generation rate (10.6% by mass) despite the small amount of residual fine particles (25% by mass compared to sample B). ) Is the same as the dust generation rate (10.5% by mass) of Sample B.

  (Q) When sample D and sample E are compared, sample E has a small amount of coarse coal (25% by mass compared to sample D), but the dust generation rate of sample E (4.4% by mass) Is the same as the dust generation rate of sample D (4.7% by mass). Also in this case, it is considered that the impact and dust generation effect of fine powder by the agglomerated coal is expressed.

  (R) There is no dust generation from sample F (agglomerated coal: 100% by mass).

  The test result (p) above (the sample B and the sample C have no difference in dust generation rate) is considered to be due to the following dust generation mechanism.

  FIG. 5 shows a dust generation mechanism when charging coal. FIG. 5 (a) shows a dust generation mechanism in the case of sample B of coarse coal (residual fine particles of 0.3 mm or less: including 19% by mass). FIG. 5 (b) shows coarse coal B: 75% by mass + agglomerated coal: The dust generation mechanism of Sample C of 25% by mass is shown.

  As shown in FIG. 5A, in the case of coarse coal Cc of sample B (residual fine particles Cf of 0.3 mm or less: including 19% by mass), when falling into the carbonization chamber, it is natural that the impact is caused by a drop impact. Residual fine particles Cf are scattered to generate dust.

  Further, as shown in FIG. 5 (b), “Coarse Coal Cc of Sample B (including residual fine powder Cf of 0.3 mm or less: including 19% by mass): 75% by mass + Agglomerated coal Cb: In the case of “25 mass%”, when falling into the carbonization chamber, the residual fine powder particles Cf are scattered and generated by the drop impact of the agglomerated coal Cb.

  In the case of the sample C, the amount of the residual fine powder particles Cf originally contained is smaller than that of the coarse coal of the sample B, but the residual fine powder particles Cf are scattered by the drop impact of the agglomerated coal Cb. It is considered that there was no difference in the dust generation rate.

  The test result of (o) is supported by another test result shown in FIG. The test results shown in FIG. 6 are the results of investigating how much the dust generation rate changes depending on the presence or absence of agglomerated coal with the same amount of residual fine particles contained in the charging coal. From this figure, it can be seen that even if the amount of residual fine particles contained in the charging coal is the same, the presence of agglomerated coal increases the dust generation rate.

  The test results of (p) and (q) above quantitatively support the existence of the impact / dust generation effect of fine powder by agglomerated coal.

  Then, the present inventors earnestly examined the estimation formula which considers the impact and dust generation effect of the fine powder by agglomerated on the assumption of the estimation formula H of patent document 11, and the estimation formula defined by following formula (1) Invented Hdst.

Hdst = k1 [HGI] + k2 [Gv] + k3 [Dp] + k4 [M] + k5 [OL]
+ K6 [Mrf] + k7 [Rsep] + k8 [Mcp] + k9 (1)
k1 to k9 are coefficients determined by multiple regression analysis (details will be described later).

  In consideration of the impact and dust generation effect of fine powder, the above formula (1) is Mrf: proportion of fine powder in coarse coal (mass%), Rsep: classification rate (mass%), and Mcp: charged coal A new term relating to the ratio (mass%) of 0.3 to 1 mm of coal particles is added to the estimation formula H by linear linear combination. The above formula (1) is the knowledge forming the basis of the present invention.

  Since the fine powder particles remaining in the coarse coal are scattered to generate dust, the amount of dust generation depends on the ratio (mass%) of the fine powder particles remaining in the coarse coal: Mrf. Therefore, the proportion of fine powder remaining in the coarse coal (mass%): Mrf was incorporated into the above formula (1) defining the dust generation amount by linear linear combination.

  In addition, agglomerated coal is involved in the impact and dust generation effect of fine particles, and the ratio depends on the classification rate (mass%): Rsep. Therefore, the classification rate (mass%): Rsep was incorporated into the above formula (1) defining the dust generation amount by linear linear combination.

  Furthermore, as shown in FIG. 7 (described later), it has been experimentally found that 0.3 to 1 mm coal particles in the charging coal are also involved in dust generation. The proportion of coal particles of 0.3 to 1 mm (mass%): Mcp was also incorporated into the above formula (1), which defines the dust generation amount, by linear linear combination.

  FIG. 7 is a diagram showing the particle size distribution before dropping of the coal sample and the particle size distribution after dropping measured by the test apparatus shown in FIG.

  FIG. 7 (a) shows the particle size distribution before and after dropping of sample D (see Table 1) of coarse coal (residual fine particles of 0.3 mm or less: including less than 1% by mass), FIG. 7 (b). These show the particle size distribution before and after the fall of sample E (see Table 1) of “coarse coal of sample D: 75% by mass + agglomerated coal: 25% by mass”.

  Each sample is a sample in which components of 0.3 mm or less are reduced as much as possible. In addition, the particle size distribution shown in FIG.7 (b) is a particle size distribution of the coarse coal except the agglomerated coal.

  7 (a) and 7 (b), it can be seen that even in the case of coal particles having a particle size of 0.3 to 1 mm, a difference occurs in the particle size distribution before and after dropping. From this, coal particles with a particle size of 0.3 to 1 mm in charging coal composed of a mixture of agglomerated coal and coarse coal are also involved in the impact and dust generation effect of fine powder by agglomerated coal. Therefore, the ratio (mass%) of coal particles of 0.3 to 1 mm in the charged coal: Mcp was also incorporated into the above formula (1) defining the dust generation amount by linear linear combination.

  After defining the above formula (1), the present inventors conducted further tests at the levels shown in Table 2 in order to determine the coefficients k1 to k9.

  The hard glove index (HGI) defined in JIS M 8801 was used as an index indicating the pulverization property of coal. Separately from HGI, a mass ratio (mass%) of coal particles of 3 mm or less (hereinafter also referred to as -3 mm%) was used as an index (Dp) representing the particle size of the actually pulverized coal.

  The measured dust generation amount is an objective function, and the coal grindability index (HGI), gas flow rate (Gv), coal particle size index (Dp), coal water content (M), oil addition rate to coal ( OL), the ratio of fine powder in coarse coal (Mrf), the classification rate (Rsep), and the ratio of 0.3 to 1 mm in charging coal (Mcp) as explanatory variables, the values shown in Table 2 Multiple regression analysis was performed on the range.

  As a result, k1 = 0.0253, k2 = 0.1756, k3 = −0.065, k4 = −0.002, k5 = −0.258 with respect to the coefficients k1 to k9 used in the above equation (1). K6 = 0.002, k7 = -0.076, k8 = 0.021, and k9 = 7.211.

  Next, in order to confirm the estimation accuracy of Hdst defined by the above equation (1), k1 = 0.0253, k2 = 0.1756, k3 = −0.065, k4 = −0.002, k5 = −0. .258, k6 = 0.002, k7 = -0.076, k8 = 0.021, k9 = 7.211, Hdst was determined, and the estimated value of dust generation amount was compared with the actual measurement value. A part of the results is shown in FIG.

  In FIG. 8, the horizontal axis represents the actual dust generation amount (mass%) obtained in the above test, and the vertical axis represents the estimated dust generation quantity (mass%) calculated by Hdst defined in the above k1 to k9.

  The correlation between the measured dust generation (mass%) and the estimated dust generation (mass%) is very good. Therefore, it is possible to accurately estimate the amount of dust generated when charging coal containing agglomerated coal, using Hdst defined by the above equation (1). However, the dust generation amount obtained by the above formula (1) is the dust generation amount when charging coal is charged into the carbonization chamber.

  In general, in actual furnaces, the amount of dust generation decreases with the passage of time since charging (see Ironmaking Conference Proceedings, AIME, 1998, p. 1041 to 1051), and the dust generation determined by the above equation (1). When the amount is incorporated into the formula for determining the growth rate of attached carbon, it is necessary to correct the dust generation amount so that the dust generation amount decreases with time. This point will be described later.

  In the patent document 11, the present inventors proposed the following formula as a formula for estimating the growth rate of attached carbon.

Doil-space-fine '
= 64.5 × Exp (k6 ′ × OL + k7 ′ × W + k8′-7950 / T) × VM
× (1-0.0476 × M) × Exp {(k9 ′ + k10 ′ × H) × (1-ξ (τ))}
H = k1 ′ [HGI] + k2 ′ [Gv] + k3 ′ [Dp] + k4 ′ [M] + k5 ′ [OL]
OL: Oil addition rate to coal (mass%)
W: Coal charge into the carbonization chamber (ton)
T: Temperature of the riser base (K)
VM: Coal volatile matter (mass%)
M: Moisture content of coal (% by mass)
H: Coal dust generation (% by mass)
ξ (τ): Correction factor τ: Elapsed time after charging coal (h)
k1 'to k10': coefficients

  The reason why the term relating to the dust generation amount H is corrected by the correction coefficient ξ (τ) in the formula “Doil-space-fine ′” will be described.

  As described above, in an actual furnace, the amount of dust generation decreases with time (see Ironmaking Conference Proceedings, AIME, 1998, p. 1041 to 1051), and therefore, “Exp (k9 ′ + k10 ′” in the above equation. If the term “× H)” is used as it is, the amount of dust generated during charging will be calculated from the amount of dust generated at the time of charging, which is inconsistent with the actual situation.

  Therefore, the present inventors have introduced a correction coefficient ξ (τ) in order to match the time lapse of the dust generation amount H with the actual state. Since the elapsed time τ after coal charging is a dimensionless time as a relative value for one cycle of dry distillation, it changes in the range of 0 ≦ ξ (τ) <1.

  The above formula “Doil-space-fine '” works effectively when the charged coal does not include agglomerated coal consisting of pulverized coal, but when the charged coal includes agglomerated coal, the actual adhesion Deviation from the growth rate of carbon.

The present inventors first experimentally investigated the relationship between the dust generation amount Hdst defined by the above formula (1) and the growth rate (kg / m ² / h) of attached carbon.

  FIG. 14 shows an outline of the experimental apparatus. First, 10 kg of coal 18 is charged into the coal supply hopper 21. Next, the carbonization vessel 24 is heated in the carbonization furnace 23, and the test material 19 installed in the exhaust pipe 27 is heated in the electric furnace 20 to raise the temperature to a predetermined temperature. When the predetermined temperature is reached, the slide gate 25 of the coal supply hopper 21 is opened, and the coal 18 is charged into the dry distillation vessel 24.

  The dry distillation gas generated from the coal heated in the dry distillation vessel 24 rises in the exhaust pipe 27 and is exhausted to the outside of the system (see generated gas flow 26). Adhesive carbon is generated on the surface of the installed test material 19.

  The temperature of the coal charged in the dry distillation vessel 24 is measured with a thermocouple (not shown). When this temperature reaches 1000 ° C., the electric furnace 20 and the dry distillation furnace 23 are turned off. When the temperature of the test material 19 decreases to near room temperature, the exhaust pipe 27 is opened, the test material 19 is taken out, and the weight is measured.

  A value obtained by calculating the amount of adhering carbon from the difference between the weight of the test material 19 measured first and the weight when the adhering carbon was generated, and dividing that amount by the product of the surface area of the test material and the carbonization time. Was defined as the growth rate of attached carbon.

FIG. 9 shows the growth rate of attached carbon measured for samples A, C, and E shown in Table 1 at temperatures of 835 ° C. and 950 ° C. (average temperature of thermocouple 22 during carbonization). (Kg / m ² / h) is shown. FIG. 9A shows the growth rate of attached carbon at 835 ° C., and FIG. 9B shows the growth rate of attached carbon at 950 ° C.

Sample A is coarse coal (residual fine particles of 0.3 mm or less: including 25% by mass), and sample C is “coarse coal of sample B: 75% by mass + agglomerated coal: 25% by mass”. And sample E is “coarse coal of sample D (residual fine particles of 0.3 mm or less: including less than 1% by mass): 75% by mass + agglomerated coal: 25% by mass”. As the amount decreases, the growth rate (kg / m ² / h) of deposited carbon decreases.

FIG. 10 shows the relationship between the amount of dust generation (mass%) and the growth rate (kg / m ² / h) of attached carbon. It is clear that reducing the amount of dust generation reduces the amount of carbon attached. Note that the lower the temperature, the greater the reduction in the amount of carbon attached. This is considered to be due to the greater contribution of carbon derived from thermal decomposition at higher temperatures.

  Based on the results of the above investigation, the present inventors replaced H in the above formula “Doil-space-fine” with Hdst defined in the above formula (1), The thickness in the horizontal direction of carbon adhering to the inner surface: The formula for estimating Doil-space-fine (mm / day) is defined by the following formula (2) (basically, the estimation formula proposed in Patent Document 11) Is the same.)

Doil-space-fine = 64.5 × Exp (k10 × OL + k11 × W + k12-7950 / T)
× VM × (1-0.0476 × M)
× Exp {(k13 + k14 × Hdst) × (1-ξ (τ))} (2)
Hdst = k1 [HGI] + k2 [Gv] + k3 [Dp] + k4 [M] + k5 [OL]
+ K6 [Mrf] + k7 [Rsep] + k8 [Mcp] + k9 (1)
OL: Oil addition rate to coal (mass%)
W: Coal charge into the carbonization chamber (ton)
T: Temperature of the riser base (K)
VM: Coal volatile matter (mass%)
M: Moisture content of coal (% by mass)
Hdst: Coal dust generation (% by mass)
ξ (τ): Correction factor τ: Elapsed time after charging coal (h)
HGI: Coal grindability index Gv: Gas flow rate (m / s)
Dp: Particle size index of coal Mrf: Ratio of fine powder in coarse coal (mass%)
Rsep: Classification rate (mass%)
Mcp: Ratio of coal particles of 0.3 to 1 mm in charging coal (mass%)
k1 to k14: Coefficient

  When the above equation (2) is applied to the operation of an actual furnace, the temperature, gas flow rate, fine powder concentration, etc. change from time to time in the actual furnace. In order to do this, as shown in the following formula (3), it is preferable to determine the amount of attached carbon for each minute section and use the sum thereof.

Doil-space-fine
= 64.5 × Σ [Exp (k10 × OL + k11 × W + k12-7950 / Tm (Δτ))
× VM × (1-0.0476 × M)
× Exp {(k13 + k14 × Hdst) × (1-ξm (Δτ))}] (3)
Δτ: Minute time (relative value for one cycle of carbonization)
Tm: Average value of temperature in minute time Δτ (K)
ξm: Average value of the correction coefficient in the minute time Δτ (−)

  Here, a procedure for accurately estimating the amount of carbon adhering to the inner surface of the riser based on the above formulas (1) and (2) and controlling the operation based on the estimated value will be described. FIG. 11 shows the procedure.

  Charging coal properties A include coal moisture content, oil addition rate, volatile matter, particle size (for example, the proportion (mass%) of coal particles of 3 mm or less (hereinafter referred to as -3 mm%)), and other HGI As a new factor, the proportion of fine powder in coarse coal, classification rate, and the proportion of 0.3 to 1 mm coal particles in the charged coal are used.

  In addition, the particle size of charging coal is not limited to -3 mm%. Particle size composition that varies depending on the type of coal, degree of pulverization, and moisture content, such as the ratio (mass%) of coal particles having a sieve particle diameter of 6 mm or less (hereinafter referred to as -6 mm%), the ratio of coal particles having a diameter of 0.1 mm or less Any particle size may be used as long as it can display correctly.

  Data relating to these factors can be obtained by daily process analysis, analysis performed at the time of arrival of coal, analysis performed when changing the composition and particle size for controlling coke quality, and the like.

  On the other hand, as the furnace operating condition B, the coal charge and the furnace wall temperature are used. Coal charge is available as operation management data. The furnace wall temperature is preferably a temperature measured by a thermometer attached to the ram head of the extruder. However, when the thermometer is not attached, the furnace wall temperature may be a temperature estimated by heat transfer calculation from an actual measurement value of the combustion chamber temperature. In addition, it is also possible to use the indicated value of the thermometer installed in the predetermined location of the furnace body for furnace temperature management.

  First, the furnace top space volume is calculated from the moisture content of coal, the oil addition rate, and the coal charge. This is a calculation for obtaining the furnace top space volume from the difference between the volume of the carbonization chamber and the filling volume calculated from the charging density of coal and the charging amount. From this furnace top space volume, the temperature of the furnace top space part is estimated based on the relationship between the furnace top space volume of the carbonization chamber and the temperature of the riser base (see Patent Document 11).

  Next, the amount of gas generated during dry distillation is determined from the operating conditions of the furnace. This is a calculation for estimating the temperature distribution in the coal packed bed of the coke oven carbonization chamber and calculating the gas generation amount from the coal for each part and every time by heat transfer calculation. The gas flow rate in the furnace top space is estimated from the obtained gas generation amount, furnace top space volume, and furnace top space temperature.

  In addition to the obtained gas flow rate, moisture content of coal, oil addition rate, particle size, and HGI, the ratio of fine powder in coarse coal as a new factor, classification rate, and 0.3-1 mm in charging coal From the ratio of coal particles, the amount of dust generated in the charged coal at the time of charging is estimated by a regression equation.

  Next, the final amount of adhering carbon is estimated from the estimated values of the furnace top space temperature and the amount of dust generation, and the coal moisture and volatile matter.

  Here, the estimated carbon amount (mass) obtained is divided by the density of the attached carbon and converted to “thickness”. This “thickness” is compared with the inner cylinder diameter of the ascending pipe to which carbon is adhered to determine the blockage state.

  That is, in the case where the time for which the adhered carbon grows to make the gas passage area of the riser to zero is shorter than one cycle of dry distillation (from coal charging into the carbonization chamber to the end of coke extrusion), during the dry distillation, The riser blockages. If clogging of the riser is predicted, the charging coal properties and / or furnace operating conditions are changed to conditions that do not clog the riser.

  A specific method for controlling the properties of the charged coal and / or the operating conditions of the furnace according to the state of carbon adhesion will be described. First, the property of the charging coal is controlled by adjusting one or more of an increase in moisture, a reduction in volatile content, and a particle size. The oil addition rate suppresses the amount of dust generated and reduces the amount of carbon adhering, but on the other hand, it increases the volatile content, so there is a conflicting effect that the amount of carbon adhering increases. It is desirable to find the optimum value.

  Under the operating conditions of the coke oven, the coal charge is effective to ensure the specified charge level, and lowering the furnace wall temperature is effective from the viewpoint of reducing the carbon deposit. However, if the furnace wall temperature is lowered, the carbonization time becomes longer and the coke productivity decreases, so a realistic countermeasure in normal operation is to secure a coal charge.

  In the coke oven carbonization chamber, if the coal charge is small and lower than the specified charge level, the furnace top space volume increases, the furnace top space temperature rises, and the carbon deposition amount increases, which is not preferable. .

  The above measures can be taken before charging coal into the carbonization chamber. For example, as disclosed in Japanese Patent Application Laid-Open No. 9-104869, the method for suppressing clogging after coal charging is as follows: (i) Reducing the top space temperature and reducing the rate of formation (growth) of attached carbon Or (ii) opening the top cover of the riser and mechanically removing carbon adhering to the inner wall surface of the riser.

  Even if the riser pipe does not become blocked, if the gas passage cross-sectional area of the riser pipe decreases, the ventilation resistance increases, the gas pressure in the furnace rises, and gas leaks from the furnace body. Therefore, even if the factors used for estimation change during dry distillation, if it can be used, it is possible to estimate the amount of carbon adhering every moment, and to estimate at which point in the dry distillation the riser blockages It becomes.

  Here, the presence or absence of clogging of the riser means that the area of the opening when carbon adheres to the inner wall surface of the riser, except for the case where gas flow is impossible due to complete clogging, there is no adhering carbon In this case, it is determined when the opening area is 80% by mass or less, preferably 50% by mass or less.

  Next, examples of the present invention will be described. The conditions in the examples are one example of conditions used for confirming the feasibility and effects of the present invention, and the present invention is based on this one example of conditions. It is not limited. The present invention can adopt various conditions as long as the object of the present invention is achieved without departing from the gist of the present invention.

(Example)
By substituting the coal properties and the coke oven operating conditions into the above equation (3) where Δτ = 0.139, the carbon adhering amount at the base of the riser pipe was estimated by the estimation formula of the present invention, and the adhering carbon amount measured. Compared with. The result is shown in FIG. The estimated value and the measured value agree very well. Therefore, the amount of carbon adhering to the riser base can be accurately estimated by the estimation formula of the present invention.

  Based on the estimation formula of the present invention, the amount of carbon adhering to the riser base was estimated, and a management system was constructed in which the riser was not blocked during dry distillation due to the growth of the adhering carbon. This management system was applied to the operation of an actual furnace, and the effect of preventing the riser blockage of the present invention was investigated. The result is shown in FIG.

  In FIG. 13, the vertical axis indicates the rate at which the riser is blocked during the period from coal charging to coke extrusion. A lower ratio means that the riser is not blocked and is in a favorable state.

  A is a conventional example before applying the present invention, and B is applied to the present invention to reduce the particle size (-3 mm%) of the charged coal from 85% by mass to 75% by mass. This is a case where the amount of dust generation at the time of entering is reduced to suppress the generation of fine powder. From FIG. 13, it can be seen that according to the management system based on the estimation formula of the present invention, the clogging rate of the riser pipe is greatly reduced.

  As described above, according to the present invention, when agglomerated coal composed of pulverized coal and coarse coal are mixed and used as charging coal, the amount of dust generation is accurately estimated, and based on the estimated value. Thus, the carbon thickness can be properly estimated, and the coke oven can be stably operated based on the estimated value. Therefore, the present invention has high applicability in the coke manufacturing industry.

DESCRIPTION OF SYMBOLS 1 Coal 2 Fluidized bed drying classifier 3 Heated gas 4 Coarse coal 5 Fine powder 6 Molding machine 7 Coal coal 8 Coke oven carbonization chamber 9 Sample 10 Sample container 11 Slide gate 12 Suction machine connection port 13 Suction port 14 Suction pipe 15 Air Inlet 16 Sample receiver 17 Air 18 Coal 19 Test material 20 Electric furnace 21 Coal supply hopper 22 Thermocouple 23 Drying furnace 24 Drying vessel 25 Sliding gate 26 Flow of generated gas 27 Exhaust pipe A Charging coal properties B Furnace operation Conditions Cc Coarse coal with a particle size of over 0.3 mm Cf Residual fine particles with a particle size of 0.3 mm or less Cb Agglomerated coal

Claims (5)

After classifying the raw coal into pulverized coal and coarse coal, the pulverized coal is agglomerated into agglomerated coal, and then the agglomerated coal and the coarse coal are charged into a chamber coke oven as charging coal. A method for estimating a dust generation amount of charging coal, characterized in that a dust generation amount Hdst (mass%) generated from charging coal during charging is estimated by the following equation (1).
Hdst = k1 [HGI] + k2 [Gv] + k3 [Dp] + k4 [M] + k5 [OL]
+ K6 [Mrf] + k7 [Rsep] + k8 [Mcp] + k9 (1)
HGI: Coal grindability index Gv: Gas flow rate (m / s)
Dp: Coal particle size index M: Coal moisture content (% by mass)
OL: Oil addition rate to coal (mass%)
Mrf: Ratio of fine powder in coarse coal (mass%)
Rsep: Classification rate (mass%)
Mcp: Ratio of coal particles of 0.3 to 1 mm in charging coal (mass%)
k1 to k9: Coefficients determined by multiple regression analysis After classifying the raw coal into pulverized coal and coarse coal, the pulverized coal is agglomerated into agglomerated coal, and then the agglomerated coal and the coarse coal are charged into a chamber coke oven as charging coal. During carbonization, the horizontal thickness of carbon adhering to the inner surface of the riser during one cycle of carbonization: Doil-space-fine (mm / day) is estimated by the following equation (2). Estimated carbon thickness estimation method.
Doil-space-fine
= 64.5 x Exp (k10 x OL + k11 x W + k12-7950 / T)
× VM × (1-0.0476 × M)
× Exp {(k13 + k14 × Hdst) × (1-ξ (τ))} (2)
Hdst = k1 [HGI] + k2 [Gv] + k3 [Dp] + k4 [M] + k5 [OL]
+ K6 [Mrf] + k7 [Rsep] + k8 [Mcp] + k9
OL: Oil addition rate to coal (mass%)
W: Coal charge into the carbonization chamber (ton)
T: Temperature of the riser base (K)
VM: Coal volatile matter (mass%)
M: Moisture content of coal (% by mass)
Hdst: Coal dust generation (% by mass)
ξ (τ): Correction factor τ: Elapsed time after charging coal (h)
HGI: Coal grindability index Gv: Gas flow rate (m / s)
Dp: Particle size index of coal Mrf: Ratio of fine powder in coarse coal (mass%)
Rsep: Classification rate (mass%)
Mcp: Ratio of coal particles of 0.3 to 1 mm in charging coal (mass%)
k1 to k14: Coefficient After classifying the raw coal into pulverized coal and coarse coal, the pulverized coal is agglomerated into agglomerated coal, and then the agglomerated coal and the coarse coal are charged into a chamber coke oven as charging coal. When carbonizing, the horizontal thickness of carbon adhering to the inner surface of the riser during one cycle of carbonization: Doil-space-fine (mm / day) is estimated by the following formula (3). Estimated carbon thickness estimation method.
Doil-space-fine
= 64.5 × Σ [Exp (k10 × OL + k11 × W + k12-7950 / Tm (Δτ))
× VM × (1-0.0476 × M)
× Exp {(k13 + k14 × Hdst) × (1-ξm (Δτ))}] (3)
Hdst = k1 [HGI] + k2 [Gv] + k3 [Dp] + k4 [M] + k5 [OL]
+ K6 [Mrf] + k7 [Rsep] + k8 [Mcp] + k9
OL: Oil addition rate to coal (mass%)
W: Coal charge into the carbonization chamber (ton)
Tm: Average value of temperature in minute time Δτ (K)
VM: Coal volatile matter (mass%)
M: Moisture content of coal (% by mass)
Hdst: Coal dust generation (% by mass)
ξm (τ): Average value of correction coefficient (−) in minute time Δτ
Δτ: Minute time (relative value for one cycle of carbonization)
HGI: Coal grindability index Gv: Gas flow rate (m / s)
Dp: Particle size index of coal Mrf: Ratio of fine powder in coarse coal (mass%)
Rsep: Classification rate (mass%)
Mcp: Ratio of coal particles of 0.3 to 1 mm in charging coal (mass%)
k1 to k14: Coefficient   Based on the adhesion carbon thickness estimated by the method for estimating the adhesion carbon thickness according to claim 2, the properties and / or operating conditions of the charging coal are adjusted in advance to suppress the adhesion of carbon to the inner surface of the riser pipe. And operating the coke oven in the room-type coke oven, which prevents the riser from being blocked.   Based on the adhesion carbon thickness estimated by the method for estimating the adhesion carbon thickness according to claim 3, during the operation, the properties and / or operation conditions of the charging coal are adjusted so that the carbon adheres to the inner surface of the riser pipe. A method of operating a coke oven, characterized by suppressing and preventing clogging of the riser pipe.

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