JP5747473B2 - Raw coal dry classification equipment - Google Patents

Description

  The present invention provides a raw material coal for forming a fluidized bed in a dry classification chamber by a high temperature gas ejected from a lower gas chamber through a dispersion plate, heating and drying the raw coal, and classifying the pulverized coal in the raw coal The present invention relates to a dry classification apparatus.

  In performing the steel manufacturing process by the blast furnace method, it is important to improve the productivity of coke, which is one of the raw materials. For this reason, before charging the coke raw material into the coke oven, it is dried and classified in advance, thereby reducing the moisture content to about 2-3% and reducing the load on the coke oven. There was a need.

  Conventionally, as an apparatus for drying and classifying the raw coal, a raw coal drying and classifying apparatus 7 has been proposed as shown in FIG. The drying classifier 7 dries the coal input from the coal input port 71 while forming and transporting a fluidized bed in the fluidized drying zone 72a. The fine-grained coal is blown up and classified in the classification zone 72b, and the coarse-grained coal forms a fluidized bed in the lower part and is transported to the discharge zone 72c. The cutting device 72d provided in the lower part of the discharge zone 72c Cut out. In other words, in the fluidized drying zone 72a, the flow of hot air for the fluid transport and drying / classification of coal is divided into the fluidized drying zone 72a and the classification zone 72b.

  In the fluidized drying zone 72a, the supplied hot air is blown out from the dispersion plate 74, and the coal is dried and fluidized and conveyed. Further, the classification zone 72b is supplied with hot air from the hot air supply pipe 73, and has a superficial velocity corresponding to a classification point for classifying the dry coal conveyed from the fluidized drying zone 72a into coarse coal and fine coal. Hot air is blown out from the dispersion plate 74 to classify coarse coal and fine coal. (For example, refer to Patent Document 1.)

  By the way, in the drying classification apparatus 7 having the above-described configuration, in particular, a fluidized drying zone 72a, a dispersion plate 74 of the classification zone 72b, and a lining plate (500 mm × x) attached to the inner surface thereof to protect the side walls. For example, ordinary steel and austenitic stainless steels such as SUS304 and SUS316L have been used as the material constituting 1500 mm). (For example, see Patent Document 2.)

However, when heated coal containing moisture comes into contact with the lining plate and the dispersion plate 74 on the side wall of the fluidized drying zone 7a made of ordinary steel, SUS304, or the like, due to Cl ^- or SO ₄ ^2- in the coal. The side wall lining plate and the dispersion plate 74 are rusted or chloride stress corrosion cracking occurs. For this reason, when the side wall lining plate and the dispersion plate 74 are made of steel as described above, there is a problem that they cannot withstand long-term use.

  On the other hand, from the viewpoint of improving rust resistance and stress corrosion cracking resistance, there are cases where a duplex stainless steel such as SUS329J is used as the dispersion plate 74 and the side wall lining plate, but because the alloy composition is high, There is also a problem that the manufacturing cost increases and becomes expensive.

  In some cases, ferritic stainless steel material was used, but the steel material was able to ensure chloride stress corrosion cracking resistance but was not expected to have rust resistance.

Japanese Patent Laid-Open No. 11-257868 JP 2008-264657 A

That is, at least as a steel material applied to each dispersion plate and / or side wall lining plate separating the gas chamber and the fluidized drying zone, the gas chamber and the classification zone in the drying classifier, in addition to the resistance to stress corrosion cracking. by applying the steel was improved rust resistance, in the coal Cl ^- was a need to prevent the by rust or SO ₄ by ^2-.

  However, an effective parameter per se focusing on rusting properties has not been proposed. For this reason, there has been a problem that it is not possible to select and examine a steel material for a dispersion plate that can realize both stress corrosion cracking resistance and rust resistance through a parameter indicating rust resistance.

  Therefore, the present invention has been devised in view of the above-mentioned problems, and the object of the present invention is to provide each of the dispersion plates and / or the gas chamber and the fluidized drying zone, the gas chamber and the classification zone, and An object of the present invention is to provide a raw coal drying classification device that selects a steel material made of a component that is inexpensive and can realize both stress corrosion cracking resistance and rust resistance for a side wall lining plate.

  In order to solve the above-described problems, the present inventor newly devised a rusting rate as a parameter indicating rusting property. This rusting rate is defined as the ratio of the rusting area in the surface area obtained by equally dividing the test piece into two in the longitudinal direction. Then, the inventor of the present invention provides a dispersion plate that separates the gas chamber and the fluidized drying zone, the gas chamber and the classified zone, and / or the side wall lining plate of the fluidized drying zone and the classified zone in the raw coal drying and classification device In order to suppress the rusting rate of the steel sheet to be applied to 3% or less, a test piece cut into a plate thickness of 2 mm, a width of 15 mm, and a length of 80 mm in a drying classifier is bent for 3 months in a U-shape. Experiments to hold were performed. As a result, it was found that the rusting rate can be suppressed by applying a steel plate as shown below to the dispersion plate and the side wall.

The raw coal drying classification apparatus according to claim 1, wherein a fluidized bed is formed in the drying classification chamber by the gas ejected from the gas chamber through the dispersion plate, and the raw coal is dried and classified in the fluidized bed. In the coal classification apparatus, the dispersion plate and / or the side wall lining plate are in mass%, Ni: 1 to 4.5 %, Mn: 1 to 6%, Cu: 0.05 to 0.8%, C: 0.08% or less, Si: 1.0% or less, Cr: 21.5 to 35%, Mo: 1.0% or less, the balance being composed of a steel plate made of Fe, N and inevitable impurities It is characterized by.

  The apparatus for drying and classifying raw coal according to claim 2 is characterized in that the jump base and the cap constituting the dispersion plate are made of the steel according to claim 1.

According to the dry classification apparatus for raw material coal having the above-described configuration, the steel material applied as the fluidized drying zone in the dry classification apparatus, the dispersion plate separating the classification zone and the gas chamber, and / or the fluidized drying zone, and the side wall lining plate of the classification zone. As mass%, Ni: 1 to 4.5 %, Mn: 1 to 6%, Cu: 0.05 to 0.8%, C: 0.08% or less, Si: 1.0% or less, Cr : 21.5 to 35%, Mo: 1.0% or less is used, and the balance is Fe, N and a steel plate made of inevitable impurities. As a result, it is inexpensive, and it is possible to prevent the dispersion plate and / or the side wall from being rusted by Cl ^- or SO ₄ ^2- in the coal, and to improve the stress corrosion cracking resistance. Become.

It is a block diagram of the dry classification apparatus of the raw material coal to which this invention is applied. It is a detailed perspective view of the dispersion plate applied to the dry classification apparatus to which the present invention is applied. It is a sectional side view of the dispersion plate applied to the dry classification apparatus to which this invention is applied. (A) is a figure which shows the shape of the test piece for measuring a rusting rate, (b) is a figure which shows the jig | tool for experiment to which this test piece is attached. It is a ternary phase diagram showing the relationship between the content of Ni, Mn, and Cu with respect to the rusting rate. It is a figure which shows the apparatus which dries and classifies the raw material coal in the past.

  Hereinafter, embodiments of a raw coal dry classification apparatus to which the present invention is applied will be described in detail with reference to the drawings.

  FIG. 1 shows a configuration of a raw coal dry classification apparatus 1 to which the present invention is applied. The drying classifier 1 has a substantially box shape, and a dispersion plate 11 is attached in the horizontal direction therein. The fluidized drying zone 17a on the upper side of the dispersion plate 11 is divided by a partition wall 16a, and the fluidized drying zone 17a and the classification zone 17b are partitioned by a partitioning wall 16b. Lined plates (not shown) are provided on the side walls of the fluid drying zone 17a and the classification zone 17b on the back side and the front side in FIG. A fluidized bed 12 is formed immediately above the dispersion plate 11, and a lower portion of the dispersion plate 11 is a gas chamber 13 into which gas is introduced. In addition, an upper portion of the dry classifier 1 is provided with a coal C charging portion 14 to be subjected to a dry classification process, and a discharge portion 15 from which the treated coarse coal is discharged is provided at the other end. The charged coal C is transferred between the lower ends of the partition walls 16a and 16b and the dispersion plate 11 in the transfer direction F indicated by the white arrow in the figure.

  The gas chamber 13 is also provided with partition walls 23 at predetermined intervals, and the gas chambers 13 partitioned by the partition walls 23 are a first gas chamber 13a to a third gas chamber below the first fluid drying zone 17a. 13c is divided into a fourth gas chamber 13d below the classification zone 17b. Further, high-temperature combustion gas is supplied to the first to fourth gas chambers 13a to 13d independently of each other, and the combustion gas is jetted to the fluidized drying zone 17a and the classification zone 17b via the dispersion plate 11. It has become so.

  Further, in the dry classifying apparatus 1, the discharge chute 15 is disposed at the end of the classification zone 17 b that is the end of the fluidized bed 12 on the transfer direction side. A vertical filling portion 25 extends in the discharge chute 15, and a cutting device (rotary valve) is provided at a discharge port 26 at the lower end thereof.

  FIG. 2 is a detailed perspective view of the dispersion plate 11 applied to the drying classifier 1 to which the present invention is applied, and FIG. 3 is a side sectional view thereof.

  A plurality of floor plates 30 are arranged with a predetermined interval in the transfer direction F of the coal C, and the end portions of the front and rear floor plates 30 are opened in a direction orthogonal to the transfer direction F, and the air inlet 31 and It has become. A semi-cylindrical cap 32 is attached between the end portions of the floor plate 30 by welding or the like so as to cover each air inlet 31. Further, the cap 32 is formed with an opening 33 toward the transfer direction F side, and is inclined obliquely upward so that the inclination angle θ with respect to the air inlet 31 is 25 ° or less (15 ° in this example). Is formed. Further, the floor plate 30 is inclined so as to incline obliquely upward from the lower portion of the cap 32 on the rear side in the transfer direction F to the upper portion of the cap 18 on the front side in the transfer direction F between the caps 32 adjacent to each other in the transfer direction F. A jump base 34 is attached by welding or the like.

  In addition, the shape of the opening 33 here may have a circular cross section, or may have an oval shape, an elliptical shape, a rectangular shape, or a trapezoidal shape.

  The atmosphere in the installation position of the test piece 5 mentioned above was temperature 60-100 degreeC, and the moisture 6-2 mass%.

  Moreover, the dry classification apparatus 1 to which the present invention is applied is not limited to the above-described configuration, and it is needless to say that each component and member may be replaced with another configuration.

  The reason why the rusting rate is set to 3% or less is based on the premise that it is not necessary to perform replacement for strength reduction due to rusting for about 10 years.

  Although the present invention may be constituted by a steel plate having a rusting rate of 3% or less for the entire dispersion plate 11, it is slightly inferior in rusting resistance as compared with the duplex stainless steel such as SUS329J. Therefore, it is preferable to use the jump stand 34 that can be easily replaced, and the above-described lining plate (not shown) of the side wall.

  The rusting rate here is a parameter indicating the rusting property of the steel sheet. The rusting rate indicates the ratio of the area where rust of the unit area of the steel plate is generated. The area where rust is generated here means an area of rust that can be identified by the naked eye or an optical microscope.

  A method for actually measuring the rusting rate will be described below.

  First, as shown to Fig.4 (a), the rectangular parallelepiped test piece 5 cut out so that plate | board thickness may be 2 mm, width 15mm, and length may be 80 mm is prepared. Next, about this test piece 5, two holes 51 are opened with an 8 * 11 mm punch. The punching position of the hole by this punch is 8.5 mm from the end of the test piece and the center is symmetric (JISG0576).

  About such a test piece 5, this is bend | folded in U shape. Next, the test piece 5 is attached to a jig 6 as shown in FIG. In this jig 6, a base material 55 made of SUS270 is inserted into a titanium bolt 54, and then a hole 51 in the test piece 5 is inserted into the bolt 54 and a PTFE (polytetrafluoroethylene) spacer. The test piece 5 is pinched by 52. Then, the bolt 54 is screwed and fixed by a titanium nut 54 through a washer 53 from the tip side. As a result, the U-shaped width of the bent test piece is about 20 mm, and the length from the end face of the bolt 54 to the end face of the nut 54 is about 62 mm.

  Such a U-shaped test piece 5 is actually installed at the partition wall 16b in the drying classifier 1, on the fluidized drying zone 17a side, and at a height of 1.5 m from the upper surface of the dispersion plate 11. For 3 months. And after exposure, the test piece 5 is taken out and the area which actually rusted is calculated | required.

  When obtaining this rusting area, for example, as shown in FIG. 4A, the ratio of the rusting area in the surface area D obtained by dividing the test piece 5 into two in the longitudinal direction A may be obtained. At this time, the surface area D is only the surface of the test piece 5 and does not include the side surface and the back surface. Actually, in order to identify this rusting area, for example, an image is taken using an electron microscope, and the image is subjected to signal processing. If the surface color changes to black and reddish brown, rusting occurs. The ratio of the rusting area and the surface area D was defined as the rusting rate.

As a result of diligent experiments on the conditions for the rusting rate thus obtained to be 3% or less, the contents of Ni, Mn, and Cu are mass%, Ni: 1 to 4.5 %, and Mn: 1 to 6. %, Cu: 0.05 to 0.8%, C: 0.08% or less, Si: 1.0% or less, Cr: 21.5 to 35%, Mo: 1.0% or less, the balance Has found that it is necessary to apply a steel plate made of Fe, N and inevitable impurities.

  Hereinafter, the reason for limiting to the range of such components will be described.

Ni: 1 to 4.5 %
Ni is an element effective for enhancing the corrosion resistance of the steel material, and the content ratio is required to be 1% or more in order to exhibit the effect. However, when the Ni content exceeds 4.5 %, the effect is saturated, and an effect commensurate with the content cannot be expected, which is economically disadvantageous. For this reason, the content rate of Ni is 1 to 4.5 %.

Mn: 1 to 6%
Mn has a content of 1% or more in order to exert the detoxifying effect of S by Mn. On the other hand, when Mn exceeds 6%, the grain boundary strength at the time of welding is lowered and a grain boundary crack is generated, and rust is generated from the cracked part to lower the corrosion resistance. I can't let you. For this reason, the Mn content is set to 1 to 6%.

Cu: 0.05 to 0.8%
Cu is added from the viewpoint of improving the corrosion resistance, and its content must be 0.05% or more. However, if the Cu content exceeds 0.8%, the effect is saturated, and an effect commensurate with the content cannot be expected, which is economically disadvantageous. Therefore, the Cu content is that is a .05 to 0.8%.

FIG. 5 shows a ternary phase diagram showing the relationship of the content of Ni, Mn, and Cu to the rusting rate. As shown in FIG. 5, the regions where the rusting rate is more than 1% and 3% or less are Ni: 1 to 4.5 %, Mn: 1 to 6%, Cu: 0.05 to 0.8%. It can be seen that the region is shown. For this reason, when paying attention to the new parameter of rusting rate, it has newly found out that it can be suppressed to 3% or less by limiting the content of Ni, Mn, and Cu to the above-mentioned range. . In addition, since rusting will progress after that if it is more than 3% of rusting, it was made into 3% or less in this invention.

In the present invention, in addition to the above chemical components, C: 0.08 wt% or less, Si: 1.0 wt% or less, Cr: 35 wt% or less, Mo: you containing 1.0 wt% or less .

  In addition, this invention is not limited to embodiment mentioned above, In addition to the application as the dry classification apparatus 1 of raw material coal, it is used for the dry classification apparatus 1, and from the rusting rate and a component mentioned above. Of course, it may be embodied as the dispersion plate 11 or the jump table 34.

  Hereinafter, the Example of the dry classification apparatus of the raw material coal to which this invention is applied is described.

Table 1 shows the components of the specimen used in the verification experiment and the measurement results of the rusting rate. Inventive Examples 1 to 5 are all included in the range defined by Ni, Mn and Cu in the present invention, and in Comparative Examples 1 to 4, any of Ni, Mn and Cu are defined in the present invention. It is out of range. Incidentally, components that are outside the range defined in the present invention are underlined.

As shown in Table 1, the inventive examples 1 to 5 all had a rusting rate of 3% or less. On the other hand, in Comparative Examples 1 to 4 that deviated from the components defined in the present invention, the rusting rate exceeded 3%.

  For this reason, it can be seen that the rusting rate can be suppressed to 3% or less by using the dispersion plate and / or the lining plate provided on the side walls of the fluidized drying zone and the classification zone as the components defined in the present invention described above. .

DESCRIPTION OF SYMBOLS 1 Drying classification apparatus 11 Dispersion plate 12 Fluidized bed 12a 1st fluidized bed 12b 2nd fluidized bed 13 Gas chamber 14 Insertion part 15 Outlet part 16 Partition wall 17 Drying classification room 18 Gap | interval 19 Ceiling 20, 21 Exhaust port 23 Partition 25 Filling portion 26 Discharge port 31 Air introduction port 32 Cap 33 Opening 34 Jump stand

Claims (2)

In a dry classification apparatus for raw coal for forming a fluidized bed in a fluidized drying zone and a classification zone by gas ejected from a gas chamber through a dispersion plate, and drying and classifying raw coal in the fluidized bed,
The dispersion plate and / or fluidized drying zone, the lining plate provided on the side wall of the classification zone,
Ni: 1 to 4.5 %,
Mn: 1 to 6%
Cu: 0.05 to 0.8%,
C: 0.08% or less,
Si: 1.0% or less,
Cr: 21.5 to 35%,
Mo: 1.0% or less of a raw material coal drying and classifying apparatus characterized in that the balance is made of a steel plate made of Fe, N and inevitable impurities.   The apparatus for drying and classifying raw coal according to claim 1, wherein the jump stand and the cap constituting the dispersion plate are made of the steel according to claim 1.

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