JP5300390B2 - Active coke for exhaust gas treatment process of moving bed system with excellent durability - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide activated coke which has a larger average grain diameter and is reduced in replenishing amount and used in an exhaust gas treatment process utilizing a moving bed system. <P>SOLUTION: The activated coke is produced by using coal as a main raw material and used in the exhaust gas treatment process utilizing the moving bed system. The activated coke has a double layer structure composed of a surface layer part having an average carbon particle filling ratio of &ge;60% and an inner layer part having an average carbon particle filling ratio of &lt;60%. It is preferable that the boundary between the surface layer part and the inner layer part is within a range of 0.5-0.9 in terms of the ratio Rm/Ri of the radius (Rm) of the inner layer part of the activated coke to the radius (Ri) of the activated coke. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to an active coke having excellent durability, and more particularly to an active coke having excellent durability for use in a moving bed type exhaust gas treatment process. The activated coke of the present invention is a molded product of activated coke produced by compression or extrusion molding, carbonization and activation of carbon-containing particles mainly made of coal such as semi-coke and caking coal. Say it.

Exhaust gas emitted from industries that burn fossil fuels such as chemicals, energy, and steel, such as petroleum and coal, contains a large amount of sulfur oxides and nitrogen oxides. It has become an important issue to reduce the emission and release into the environment. Many methods have been developed for exhaust gas treatment technology that removes these sulfur oxides and nitrogen oxides from exhaust gas, for example, desulfurization and denitration technologies, but a moving bed utilizing adsorption and catalytic action by active coke. The dry desulfurization / denitrification method of the system is often employed because the treatment of the removed sulfur oxides and nitrogen oxides is easier than the wet system. The activated coke is industrial activated coke, and the main raw material is coal (caking coal) or semi-coke. Hereinafter, a dry desulfurization denitration process will be described as an example of the exhaust gas treatment process, but the present application is not limited to this.
In the moving bed type dry desulfurization denitration process, the active coke moves down in the dry denitrification process (reaction tower) due to gravity. In addition to mechanical loss in which the surface of the active coke is cracked or chipped due to contact between the active cokes in the meantime or contact with the apparatus wall, so-called mechanical loss, in particular, in the process of regenerating the active coke, SOx in the gas or Due to the chemical loss that is consumed as a reducing agent due to the reaction with oxygen mixed therein, the particle size of the activated coke after passing through the process decreases. After removing the active coke having a reduced particle size or pulverized active coke, if necessary, new active coke is replenished and added, and the cycle is used again by charging in the process.
However, due to repeated use, the average particle diameter of the active coke in the moving bed as a whole gradually decreases until it reaches a steady state, and it is inevitable that the pressure loss of the processing gas increases.
Therefore, the active coke suitable for this has high SOx adsorption capacity, high NOx removal ability under the addition of NOx NH _3, and suppresses impacts in the moving bed, destruction due to wear, and powdering due to reaction. Therefore, high durability is required.

On the other hand, for example, in Patent Document 1, semi-finished coke obtained by subjecting coal to low temperature carbonization at 300 to 600 ° C. is used as a main raw material, caking coal as a secondary raw material, mixed with a binder, and carbonized. In the production of activated activated carbon, the coal for semi-coke raw material has high mobility and high adsorbing capacity by making the amount of mobile hydrogen component calculated from NMR measurement results at the softening and melting temperature 30% or less. It is disclosed to make activated carbon having
Patent Document 2 discloses that volatile matter is 2.0% or more, fixed carbon is 87 to 94%, Fe ₂ O ₃ + TiO ₂ is 0.7% or more, and K ₂ O + Na ₂ O + MgO is 0.00. An activated carbon that is 3 to 1.0% is disclosed.
As described above, in these patent documents, a method for producing activated carbon, which is said to have high strength, excellent desulfurization performance with high adsorption ability, and withstand cyclic use in a moving bed type dry desulfurization denitration process, and an impact strength of 97 %, Logger strength 96% or more, SO ₂ adsorption capacity 70 mg / gr or more, denitration rate 20% or more under ammonia addition, and pulverization rate 1.0% or less activated carbon for desulfurization and denitrification have been proposed.
Patent Document 3 discloses an activated carbon made of coal as a raw material for vapor phase adsorption of volatile substances such as gasoline, having a hardness of 90% or more and a surface area of 500 to 1000 m ² / cc. There has been proposed an activated carbon which has a pore diameter of 24 to 60 mm on the surface and a volume of 0.1 cc / cc or more, an activated carbon having an average diameter of 0.5 to 2.5 mm and does not increase the airflow pressure loss.
In Patent Document 4, a large particle size coal powder and a small particle size coal powder are mixed to maintain the coke core strength, and the coal fine powder is adhered around the large particle size coal powder. It is disclosed that internal pores are promoted and the surface layer is reinforced.
JP 2002-348111 A JP 2002-355557 A JP 7-277716 A JP-A-11-349317

However, in the activated coke proposed in Patent Documents 1 and 2, the moving bed type exhaust gas treatment process is insufficient for reducing durability and pressure loss, and the activated carbon of Patent Document 3 is a moving bed type exhaust gas. It is not intended for processing processes. Patent Document 4 does not disclose that the particle distribution is controlled in the radial direction to have an intensity distribution. Although it is possible to improve the wear resistance, it is difficult to increase the average particle size in the exhaust gas treatment process.
In order to find active coke having excellent durability and low pressure loss, the inventors have examined the durability of these active cokes and the factors affecting pressure loss in the reaction tower.

A moving bed type exhaust gas treatment process (for example, an adsorption tower of a dry desulfurization denitrification process) is filled with 1000 to 4000 tons of active coke, and these activated cokes are extracted after passing through the adsorption tower. The regeneration and re-charging are repeated about 50 to 100 times, and after a long period of time, for example, the initial particle diameter (diameter) Di: from 9.0 to 9.5 mm to a particle diameter of 1 mm or less It will wear out. Active coke that has been worn down to a certain particle size (usually Do: less than 1.5 mm) is screened out of the process and replenished with new active coke that is commensurate with that amount. By repeating this, the particle size of the active coke in the reaction process converges to a certain steady state particle size distribution after a certain period of time.
In the present invention, the active coke sampled in a converged state (steady state) in the reaction process is investigated for the average particle diameter, the number ratio of particles, and the like, and the characteristics of the active coke are compared and evaluated. . In the following description, unless otherwise specified, the average particle diameter, the number ratio of particles, and the like refer to the properties of active coke in the samples sampled in the above state.

  By the way, in the moving bed type exhaust gas treatment process as described above, since active coke formed into a cylindrical body is usually used, in the present invention, active coke is formed into a cylindrical body. Let's take an example. That is, chemical loss and mechanical loss proceed not only in the radial direction of the cylindrical body but also in the axial direction, but in the evaluation of the shape of the active coke according to the present invention, the diameter of the cylindrical body is a representative example and will be described as the particle diameter. . However, it goes without saying that the activated coke of the present invention is not limited to a cylindrical shape, and may be spherical or elliptical.

Various conventional activated cokes S1 and S2 (initial particle size (diameter) S1: Di: 9.4 mm and S2: Di: 9.3 mm) are packed in a moving bed type reaction tower, and combustion exhaust gas is put into the reaction tower. Was investigated by paying particular attention to particle size distribution, average particle size, particle number ratio, and the like.
The “conventional active coke” (active coke S1, S2, conventional active coke (i), (ii), etc.) referred to in the present invention means a commercially available active coke purchased.

FIG. 15 shows the particle size distribution and the average particle size after using S1 and S2 of the conventional activated coke for a certain period in the desulfurization and denitrification process, but the average particle size is reduced due to mechanical wear and chemical loss. It is getting smaller.
FIG. 16 shows the ratio of the number of particles of the above-mentioned active coke S1 and S2, that is, the number of particles for each particle size range after a certain period of use as a ratio to the initial number of particles. For example, 300% This indicates that the number of particles in the range has increased three times due to cracking of the active coke. As can be seen from FIG. 16, the smaller the particle size ratio, the larger the particle number ratio. This change in the particle size distribution indicates that the particles are not only uniformly worn and become smaller in diameter during circulation use, but also the particles are cracked on the way to become smaller.

  In the moving bed type desulfurization / denitrification process, the decrease rate of the activated coke particle size due to chemical loss or mechanical loss (hereinafter also referred to as wear rate) may be relatively increased as the particle size of the activated coke decreases. It is generally known, therefore, the amount of replenishment increases when cracked during use to reduce the particle size.

FIG. 17 shows the relationship between the average particle diameter of activated coke and the pressure loss of exhaust gas in the adsorption tower (reaction tower) of the desulfurization and denitrification process. The smaller the average particle diameter, the pressure loss of exhaust gas in the adsorption tower. Therefore, it can be seen that the average particle size of the activated coke has a great influence on the operation of the desulfurization and denitration process.
Therefore, active coke suitable for use in a moving bed type exhaust gas treatment process and having a small pressure loss and a small replenishment amount has a low wear rate, is hard to crack, and can maintain a large average particle size. It turns out that coke is important.
An object of the present invention is to provide an active coke that can be used in such a moving bed type exhaust gas treatment process and that can maintain a large average particle diameter and that is difficult to break and can reduce the replenishment amount.

First, the inventors of the present invention focused on the fact that the conventional active coke is easily cracked, the average particle diameter is reduced by the cracking, and the wear rate is further increased. The effect of increasing the size and making it difficult to break was examined by analysis.
That is, it is assumed that activated coke with uniformly enhanced radial strength i) does not crack in the middle, ii) the rate of radial wear is constant, and iii) wear occurs only in the radial direction. The average particle diameter of the activated coke which has been used for a certain period in the moving bed type exhaust gas treatment process and has reached a steady state can be obtained by simple calculation.
Considering a single active coke, the particle size of the active coke is reduced in proportion to time, but it is assumed that wear occurs only in the radial direction, so the weight of the active coke is the square of the particle size. It will be proportional.

In the above analysis, the strength is uniformly increased in the radial direction of the active coke, that is, the wear rate is the same in all regions, that is, the initial particle size Di of the active coke is 9.5 mm, and the size is removed by a sieve. Do was less than 1.5 mm.
As a result, as shown in Table 1, an average particle diameter of 7.14 mm was obtained.

On the other hand, as described above, when the conventional activated coke is actually used in the moving bed type desulfurization denitration process, when the initial particle diameter Di is 9.3 mm (S2), as shown in FIG. The average particle diameter is around 7.3 mm, which is not significantly different from the case where it is assumed that the entire active coke is strengthened almost uniformly in the analysis. That is, if the entire active coke is uniformly strengthened, cracks are reduced and the replenishment amount can be reduced, but the average particle size is the same as the conventional one, and the effect of reducing the pressure loss cannot be expected. understood.
For this reason, the inventors next focused on the cross-sectional structure of the active coke (here, the active coke formed into a cylindrical shape is assumed, and the cross-sectional structure is a cross section perpendicular to the cylinder axis), Consider the average particle size when the active coke strength is not uniform in the radial direction but the active coke has a two-layer structure (surface layer and inner layer) with a difference in strength or wear rate in the radial direction. did.

That is, the change in the average particle diameter in the case of the active coke having a structure in which the wear rate was changed in the radial direction of the active coke was analyzed and examined.
FIG. 1 is a schematic view showing a state of a cross section perpendicular to the central axis of the active coke having a two-layer structure of the present invention.
In this analysis, the active coke 1 is divided into two sections of the surface layer portion 2 and the inner layer portion 3 in the radial direction, and the wear rate on the center side (inner layer portion) is larger than 1 with respect to the wear rate 1 of the surface layer portion. It was. Here, the wear rate ratio is defined as the wear rate of the inner layer portion / the wear rate of the surface layer portion. That is, a wear rate ratio of 5 indicates that the wear rate of the inner layer portion is five times the wear rate of the surface layer portion. This wear rate ratio is related to the crushing strength of the activated coke as will be described later. Further, the boundary position 4 in the radial direction dividing the surface layer portion and the inner layer portion is changed. The boundary position 4 can be represented by a ratio Rm / Ri of the inner layer radius Rm to the initial radius Ri.
In this analysis, the initial particle diameter Di was 9.5 mm, and the sieve diameter Do to be removed was 1.5 mm, as described above.

Active coke has a two-layer structure, and the active coke has a uniform strength in each layer. I) There is no cracking in the middle, ii) The radial wear rate in each layer is constant, and iii) Assuming that wear occurs only in the radial direction, the average particle diameter of the activated coke that has been used for a certain period in the moving bed type exhaust gas treatment process and has reached a steady state can be obtained by simple calculation.
In other words, when focusing on a single active coke, the particle size of the active coke decreases (wears) in proportion to time, but wear is assumed to occur in the radial direction. The residence time becomes shorter in inverse proportion to the wear rate, but the number ratio of each particle size range is proportional to this stay time. That is, the product of the wear rate and the number ratio in each particle size range is a constant value. The average particle size was determined using this relationship, and the results are shown in Table 1. For comparison, Table 1 shows the results when the single-layer structure, that is, the above-described wear rate is uniform in the radial direction (wear rate ratio 1).
For example, the boundary position between the surface layer portion and the inner layer portion of the active coke having a two-layer structure has a particle size of Dm = 8 mm (Rm = 4 mm), and the wear rate is defined as the surface layer portion 1 and the inner layer portion 4 (wear rate ratio 4). In the example of the active coke, as shown in Table 1, the average particle diameter is 8.045 mm, and the average particle size of the active coke in the case of the single layer structure shown as the comparative example, that is, the wear rate is uniformly all 1. It can be seen that the average particle size can be greatly increased compared to the diameter of 7.14 mm.

  The inventors further changed the wear rate ratio in this analysis from 1.25 to 16, that is, the wear rate 1 of the surface layer portion to a range of 1.25 to 16 times that of the inner layer portion. The boundary position (Rm / Ri) between the surface layer portion and the inner layer portion was changed, and the average particle diameter was determined in each case.

FIG. 2 shows the result, and it can be seen that the average particle diameter tends to increase as the wear rate ratio increases, in other words, the wear rate of the inner layer portion is larger than the wear rate of the surface layer portion. . Moreover, it turns out that an average particle diameter changes with the magnitude | size of the wear rate ratio of a surface layer part and an inner layer part, and the boundary position which divides a surface layer part and an inner layer part. Then, it can be seen that Rm / Ri at the boundary position (hereinafter, this boundary position is also referred to as the optimal boundary position) when the average particle diameter is maximum (maximum average particle diameter) also varies depending on each wear rate ratio.
Based on the results of FIG. 2, the relationship between the wear rate ratio and the maximum average particle size is shown in FIG. It can be seen that the average particle diameter can be increased by increasing the wear rate ratio, that is, by increasing the wear rate of the inner layer portion relative to the wear rate of the surface layer portion.

FIG. 4 shows the relationship between the wear speed ratio and Rm / Ri at the boundary position (optimum boundary position) between the surface layer portion and the inner layer portion when the maximum average particle diameter is obtained. The horizontal axis in FIG. 4 indicates the wear rate ratio as a logarithmic value.
For example, from FIGS. 3 and 4, when the wear rate ratio is 1.25, the maximum average particle diameter is 7.30 mm, and the optimum boundary position Rm / Ri is 0.78, but the wear rate ratio is 8 In this case, the maximum average particle diameter is 8.36 mm, and Rm / Ri at the optimum boundary position is approximately 0.87.

  Further, as can be seen from FIG. 4, the boundary position (optimum boundary position) Rm / Ri for separating the surface layer portion and the inner layer portion when the maximum average particle diameter is given increases as the wear rate ratio increases. That is, as the wear rate ratio is larger, the optimum boundary position is closer to the surface, and is found to be in the range of 0.5 to 0.9.

  The inventors conducted the same analysis when the initial particle diameter Di of the active coke was 5.6 mm and 15 mm in addition to the above case of 9.5 mm. According to this, the boundary position (optimal boundary position) when the average particle diameter is maximum varies depending on the wear rate ratio, but the range is considered to be in the range of about 0.5 to 0.9. It was found that the initial particle size was not significantly affected.

As described above, the active coke has a two-layer structure of the surface layer portion and the inner layer portion, and with respect to the wear rate of the surface layer portion, that of the inner layer portion is increased, that is, the wear rate ratio is set to be greater than 1. It was found that the particle size can be increased.
The inventors have found the carbon particle filling rate of the active coke as an element for controlling the strength and wear rate of the above-mentioned active coke, and confirmed that this is closely related to the above characteristics. That is, the strength and wear rate can be controlled by adjusting the carbon particle filling rate of the activated coke. As a result of confirming the knowledge obtained by the above-mentioned analysis by trial production and evaluation of activated coke by controlling the carbon particle filling rate, as described above, the wear rate of the inner layer portion is changed to the wear rate of the inner layer portion as described above. On the other hand, by increasing the two-layer structure and strengthening the surface layer portion, it was possible to increase the average particle diameter and to obtain active coke that is difficult to break.

This invention is based on said knowledge, and makes the following a summary.
(1) Activated coke used in a moving bed type exhaust gas treatment process manufactured using coal as a main raw material, the activated coke comprising a surface layer portion having an average carbon particle filling rate of 60% or more, an average carbon An active coke for an exhaust gas treatment process of a moving bed system characterized by having a two-layer structure having an inner layer portion with a particle filling rate of less than 60%.
(2) The movement according to (1), wherein a boundary between a surface layer portion and an inner layer portion of the active coke is in a range of 0.5 to 0.9 in a ratio Rm / Ri of the radius of the active coke. Activated coke for exhaust gas treatment process of layer system. Where Rm is the radius of the inner layer of the active coke and Ri is the radius of the active coke.
(3) The ratio according to (1) or (2), wherein the ratio of the average carbon particle filling factor of the surface layer part to the average carbon particle filling factor of the inner layer part of the activated coke is 1.07 or more. Activated coke for exhaust gas treatment process of layer system.

According to the present invention, the carbon particle filling rate of the active coke is not uniformly increased from the center to the surface, but the carbon particle filling rate of the surface layer portion of the active coke has a two-layer structure larger than the inner layer portion, and By making the average carbon particle filling rate of the surface layer portion 60% or more, it is preferable that the boundary between the surface layer portion and the inner layer portion is in the range of 0.5 to 0.9 in terms of the active coke radius ratio Rm / Ri. In addition, preferably, when the ratio of the average carbon particle filling rate of the surface layer portion to the average carbon particle filling rate of the inner layer portion is 1.07 or more, the active coke is filled in the moving bed and used. It is possible to suppress the active coke from cracking and reducing its diameter due to wear or impact of the material, and to reduce the replenishment amount. Moreover, since the average particle diameter can be maintained larger, the pressure loss in the exhaust gas treatment process can be reduced.
That is, the activated coke of the present invention has a two-layer structure in which the average carbon particle filling rate of the surface layer portion is higher than that of the inner layer portion. As a result, first, the strength of the surface layer portion can be improved, it can be made difficult to break, the wear rate can be reduced, the durability can be improved, and the replenishment rate of active coke can be reduced. Next, as described above, the average carbon particle filling rate of the inner layer portion of the active coke is lower than that of the surface layer portion. Wear out. Accordingly, it is possible to suppress the small-diameter particles from staying in the reaction system for a long period of time, that is, to maintain a large average particle diameter. The present invention ensures the durability by making the active coke as described above, and can achieve two purposes by increasing the average particle diameter, reducing the replenishment rate of the active coke, The pressure loss in the reaction system can be reduced.

Hereinafter, the present invention will be described more specifically.
In the present invention, in order to specifically realize the active coke having the two-layer structure as described above, the carbon particle filling rate in the cross-sectional structure of the active coke is introduced as a control index reflecting the strength or wear rate of the active coke. The relationship between this and the properties of active coke such as structure, strength, and average particle size was investigated. That is, the carbon particle filling rate is defined as that obtained by the following method.
In this method, active coke (cylindrical body) is embedded in resin, a cross section perpendicular to the cylinder axis of the active coke is polished, and this cross section is observed with a microscope at a magnification of 200 times. Compared to the real image for a field of view of about 500 μm × 300 μm, the gradation is fixed to 200, which is near the minimum frequency of 256 gradations so as to be two types of carbon particles and pores, binarized in black and white, and pore area ( The minimum unit 1 μm ² ) and the area of carbon particles (carbon matrix) are measured. Next, the carbon particle filling rate (%) = carbon particle area / (carbon particle area + pore area) × 100 is obtained.

  About one active coke, it becomes an observation visual field for every about 500 micrometers width | variety from the center of the cross section of an active coke to radial direction, for example, in the case of an active coke with a diameter of 9.5 mm, it becomes nine visual fields. Here, FIG. 5 is a schematic diagram showing, as an example, a field of view of a cross section perpendicular to the axial direction of an active coke having a particle size (diameter) of 9.5 mm, and an observation range (observation range (1)) from the center to the left and right. The field of view for each width of about 500 μm in the observation range (2) is shown.

FIGS. 6A and 6B exemplify a situation of microscopic observation in the field of view of the surface layer portion and the inner layer portion in the cross section of the active coke. FIG. 6A is a real image, and FIG. 6B is an image obtained by binarizing the real image into black and white. From this binarized image, the carbon particle filling rate can be obtained by the method as described above.
The average carbon particle filling rate is an area weighted average of the carbon particle filling rate of the active coke measured in a series of multiple visual fields in the radial direction unless otherwise specified. For example, the observation range (1) shown in FIG. Alternatively, the carbon particle filling rate in each field of view of the observation range (2) is an area weighted average according to the radius region.
In the investigation of the carbon particle filling rate, the number of active cokes to be investigated is not particularly specified, and one active coke may be investigated, but about 5 to 10 in consideration of some variation. It is preferable that the average value be the carbon particle filling rate of the lot.

Next, the inventors investigated the relationship between the carbon particle filling rate, strength (crush strength), and wear rate. As described later, in the production of activated coke, a conventional single-layer structure having a substantially uniform carbon particle filling rate in the radial direction and a surface layer by changing the molding conditions such as the particle size of the raw coal or the die shape An active coke having a two-layer structure in which the carbon filling rate is different between the inner portion and the inner layer portion was manufactured by changing the overall average carbon particle filling rate level, and the strength (crushing strength) was measured by a crushing strength test. FIG. 7 shows the relationship between the average carbon particle filling rate and the crushing strength.
FIG. 7 confirms that there is a clear correlation between the simple average carbon particle filling rate of active coke and the strength (crushing strength), and it has been found that the strength is improved when the carbon particle filling rate is high. .

  It is also known that the active coke wear rate in moving bed type exhaust gas treatment is closely related to the strength of the active coke, and improving the strength has been an important factor for suppressing the wear of the active coke. It is said that. As described above, it has been confirmed that there is a clear correlation between the strength (crushing strength) of active coke and the average carbon particle filling rate, and the average carbon particle filling rate is closely related to the wear rate.

  In order to confirm this, the inventors used six types of active coke in which the average carbon particle filling rate was changed between 53.9% and 64.2%, and the durability of the active coke was confirmed. The sulfuric acid strength test described later for evaluating the property (abrasion resistance) was conducted, and the number of repeated tests until the residual ratio reached approximately 20% by mass was investigated. Durability was evaluated using the ratio of the number of tests of other active cokes to the number of tests of active coke with an average carbon particle packing ratio of 53.9% (the level of the average carbon particle filling ratio of conventional active coke) as the wear rate ratio. . The result is shown in FIG. As shown in FIG. 8, the result that the wear rate ratio becomes smaller as the carbon particle filling rate becomes higher was obtained. As can be seen from FIG. 8, it was confirmed that the wear rate ratio of the activated coke was also closely related to the carbon particle filling rate. An increase in the carbon particle filling rate means that the carbon particles inside the activated coke are densely bonded, which improves strength and at the same time suppresses wear, resulting in a reduced wear rate. Think.

  As mentioned above, it was confirmed that the above-mentioned carbon particle filling rate becomes an index for controlling and evaluating the strength or wear rate of activated coke. In the present invention, this carbon particle filling rate is used to control the structure of the active coke having a two-layer structure and evaluate the characteristics.

  The inventors investigated the carbon particle filling rate of the active coke (single layer structure) (i) and (ii) having a particle diameter of 9.4 mm, which has been conventionally used. The results are shown in Table 2. On the very surface of 4.5 to 5 mm in the radial direction from the center, although the carbon particle filling rate is slightly higher than other parts, it varies in the radial direction. The average value is about 54 to 55 (%).

Next, based on the cross-sectional state of these conventional active cokes, an active coke having a two-layer structure having a surface layer portion with a high carbon particle filling rate and a low inner layer portion as described above was prototyped. First, trial production of active coke (a), (b), (c), (d) with varying boundary positions Rm / Ri for dividing the carbon particle filling rate, and its strength characteristics (logger strength and crushing strength) investigated.
Table 2 shows the structure, properties (carbon particle filling rate, Rm / Ri ratio), and strength characteristics of the prototype activated coke (a), (b), (c), and (d). In Table 2, the conventional active coke (single layer structure) (i) and (ii) are also shown for comparison.

  In the active coke (a), (b), (c) of the present invention having a two-layer structure, the boundary position Rm / Ri between the surface layer portion and the inner layer portion is different, but the carbon particle filling rate of the surface layer portion is 62 to 65%, the average carbon particle filling rate was 62 to 63%, the carbon particle filling rate of the inner layer portion was 52 to 59%, and the average carbon particle filling rate was 57 to 58%. In the active coke (d), the boundary position Rm / Ri is 0.74, which is substantially the same as that of the active coke (b). However, in the surface layer portion, the carbon particle filling rate is about 59%, and the average carbon particle filling rate is about The inner layer portion had a carbon particle filling factor of 54 to 57%, an average carbon particle filling factor of 55.6%, and an overall average carbon particle filling factor of 57.2%. On the other hand, the conventional activated coke varies from 54 to 59% from the surface layer portion to the inner layer portion as described above, and the average carbon particle filling rate is about 54 to 55%.

  The activated coke (a) to (d) of the present invention has a two-layer structure in which the carbon particle filling rate of the surface layer portion is higher than that of the inner layer portion, and the strength characteristics (crush strength) are superior to the conventional one. I understand. In addition, the boundary position between the surface layer portion and the inner layer portion in the two-layer structure, that is, the Rm / Ri ratio was changed from 0.5 to 0.9. In either case, the single-layer structure of the conventional active coke is used. Compared to those, the strength characteristics (crush strength) are superior. The logger strength was almost the same level as in (a) to (d) and the conventional (i) and (ii), and it was found that it was difficult to say that the structural characteristics of the active coke were sufficiently reflected. Therefore, the following strength characteristics are mainly evaluated by crushing strength.

Moreover, when active coke (a)-(c) and (d) are compared, it turns out that the crushing strength of (a)-(c) is clearly high compared with (d). This is presumably because the average carbon particle filling rate of the surface layer part is as low as less than 60% in (d) while (a) to (c) is 60% or more. For this reason, in this invention, the average carbon particle filling rate of a surface layer part shall be 60% or more.
That is, in order to make active coke difficult to crack and reduce wear, it is necessary to ensure a certain level of crushing strength.

  The boundary position between the surface layer portion and the inner layer portion in the two-layer structure, that is, Rm / Ri is not particularly limited, but if it exceeds 0.9, the surface layer portion is too thin, and sufficient strength and wear rate improvement effects are obtained. On the other hand, if it is less than 0.5, the improvement effect is saturated, and the production cost increases to raise the carbon particle filling rate to the inside highly. Is preferred. More preferably, it is the range of 0.75-0.9.

In addition, the ratio of the average carbon particle filling rate of the surface layer portion to the average carbon particle filling rate of the inner layer portion of the active coke having a two-layer structure is preferably 1.07 or more. This is because, if this ratio is less than 1.07, the effect of improving the strength and wear rate in the case of the two-layer structure is reduced.
This ratio is preferably 1.06 or more, more preferably 1.10 or more.

  On the other hand, the conventional activated cokes (i) and (ii) have a single-layer structure in which the carbon particle filling rate varies from the surface layer portion to the inner layer portion, and the total average carbon particle filling rate is the activity of the present invention. Low compared to coke. The active coke (d) of the present invention and the conventional active coke (ii) have a similar total average carbon particle filling rate, but the active coke (d) having a two-layer structure has strength characteristics (crushing strength). ) Is far superior to the conventional activated coke (ii), and it can be seen that the activated coke having a two-layer structure is advantageous in terms of wear rate and the like. However, as described above, the crushing strength is low and the durability is slightly inferior to the active cokes (a) to (c) of the present invention.

In the activated coke having a two-layer structure of a surface layer portion with an average carbon particle filling ratio of 60% or more and an inner layer portion of less than 60% according to the present invention, the boundary position Rm / Ri between the surface layer portion and the inner layer portion is a carbon particle filling ratio. From the measurement results, the following is obtained.
About the cross section (cross section perpendicular | vertical to an axial direction) of the shape | molded active coke, as shown in FIG. 5, for every range of 500 micrometers from the center toward the surface, for example, 0 [center] -0.5 mm, 0.5- The carbon particle filling rate is measured as 1.0 mm, 1.0 to 1.5 mm. In addition, the measurement position of the carbon particle filling rate in the range is represented by the upper limit value of the radius in each range. That is, representative measurement positions in each range are 0.5 mm, 1.0 mm, 1.5 mm, and so on.

Next, the boundary between the surface layer and the inner layer is assumed (hereinafter referred to as an assumed boundary position) with respect to the measurement positions for every 500 μm described above, and the center side is defined as the inner layer portion and the surface side is defined as the surface layer portion. Based on the carbon particle filling rate measured every 500 μm, the average carbon particle filling rate of the surface layer portion and the inner layer portion is calculated. In addition, let the value of this average carbon particle filling rate be an area weighted average value as mentioned above.
That is, the assumed boundary position is sequentially shifted from the center side to the surface side (by 500 μm), and the average carbon particle filling rate of the surface layer portion and the inner layer portion at each assumed boundary position is obtained. When the measurement range of the carbon particle filling rate set from the center side is less than 500 μm, the range is omitted. The outermost layer (approximately 0.1 mm from the surface) is hardened by the influence of contact with the die during the molding process, heating during the carbonization process, etc., and the carbon particle filling rate is often significantly higher than other parts. In addition, since the thickness is very small in this range, the evaluation of the durability and wear resistance of the active coke particles as a whole does not impair the effects of the present invention even if this portion is excluded. Because. In the present invention, it is needless to say that the surface layer is a surface layer portion including the outermost surface layer.

  Next, based on the average carbon particle filling rate of the surface layer portion and the inner layer portion, the ratio of the surface layer portion / inner layer portion of the average carbon particle filling rate at each assumed boundary position is calculated. Then, in the relationship between the assumed boundary position and the ratio of the surface layer portion / inner layer portion of the average carbon particle filling rate, (a) a convex inflection point was recognized in the surface layer portion / inner layer portion ratio of the average carbon particle filling rate. If the inflection point is not clear, (b) if the inflection point is not clear, at the assumed boundary position where the maximum ratio of the surface layer / inner layer ratio of the average carbon particle filling rate is recognized, If the average carbon particle filling rate of the surface layer portion is 60% or more, the assumed boundary position is the boundary position between the surface layer portion and the inner layer portion of the active coke having the two-layer structure of the present invention. To do. That is, at the true boundary position between the surface layer portion and the inner layer portion in the two-layer structure, the ratio of the surface layer portion / inner layer portion of the average carbon particle filling rate greatly changes before and after that.

FIG. 9 is a diagram for explaining the setting of the boundary position of the active coke (b) of the present invention shown in Table 2. FIG. 9 shows the relationship between the assumed boundary position (Rm / Ri), the ratio of the surface layer portion / inner layer portion of the average carbon particle filling rate, and the average carbon particle filling rate.
As can be seen from FIG. 9, when the assumed boundary position Ri / Rm is moved from the center to the surface side, an upward inflection point exists at a position of 0.76. Moreover, the average carbon particle filling rate of the surface layer part when this position is taken as a boundary is 60% or more, and this position can be determined as the boundary position between the surface layer part and the inner layer part. That is, it can be determined that the coke has the two-layer structure of the present invention. When a plurality of inflection points are seen, the assumed boundary position where the ratio of the surface layer portion / inner layer portion of the average carbon particle filling rate is the largest can be determined as the boundary position, and a two-layer structure can be determined.

  FIG. 10 is a diagram for explaining the setting of the boundary position of the active coke (a) of the present invention in Table 2. FIG. 10 shows the relationship between the assumed boundary position (Rm / Ri), the ratio of the surface layer portion / inner layer portion of the average carbon particle filling rate, and the average carbon particle filling rate, as in FIG. As can be seen from FIG. 10, when the assumed boundary position (Rm / Ri) is moved from the central part to the surface side, the ratio of the surface layer part / inner layer part is maximized at a position where Rm / Ri is 0.86, The average carbon particle filling rate of the surface layer portion at this position is 60% or more, and this position can be set as a boundary position between the surface layer portion and the inner layer portion. In the case of the activated coke (a), the upper limit between the assumed boundary position (Rm / Ri) and the ratio of the surface layer portion / inner layer portion of the average carbon particle filling rate as in the activated coke (b) shown in FIG. Although the inflection point that becomes convex is not seen, the surface layer portion can be obtained by considering the position where the ratio of the surface layer portion / inner layer portion of the average carbon particle filling rate is maximum and the average carbon particle filling rate at that position. And the boundary position between the inner layer and the inner layer can be set.

  In this way, the active coke has a two-layer structure having a surface layer portion having a high average carbon particle filling rate of 60% or more and an inner layer portion having a lower average carbon particle filling rate, thereby improving the strength and making it difficult to break. Thus, the wear rate is improved and the replenishment rate can be reduced. Further, when the wear progresses and the diameter becomes small to some extent, the wear is accelerated by the inner layer portion having a low carbon particle filling rate, and the time for staying in the system as particles with a small particle size is shortened. When used in an exhaust gas treatment process, the average particle size can be maintained large, and the pressure loss of the exhaust gas can be reduced.

As described above, the activated coke having a two-layer structure according to the present invention can reduce the replenishment rate and maintain a large average particle size in the moving bed type exhaust gas treatment process, and the exhaust gas pressure loss in the process. This active coke can be obtained by adjusting the carbon particle filling rate during production.
FIG. 11 is a diagram illustrating an example of a process for producing activated coke according to the present invention. The activated coke of the present invention is mainly made of coal, that is, semi-coke coal and caking coal as semi-coke as a raw material. Coal which is subjected to low temperature carbonization treatment to form raw semi-coke is charged into a low temperature carbonization furnace, and usually has a heating atmosphere with an oxygen concentration of 1% by mass or less and 300 to 600 ° C, preferably 400 to 550 ° C. In the furnace, pre-distillation is carried out under the condition that the residence time in the furnace is 15 minutes to 150 minutes or less to obtain semi-coke. This semi-coke is put into a grinder and pulverized, and then stored in a semi-coke powder hopper. Moreover, caking coal is also put into a grinder and pulverized, and then stored in a caking coal powder hopper.

  Next, the pulverized semi-coke powder and caking coal powder are cut out from each hopper at a ratio of 9: 1 to 5: 5 and kneaded in a kneader. At that time, coal-based or petroleum-based oil as a binder and a hydrophilic oil as a molding aid are simultaneously added and kneaded. This kneaded product is introduced into a granulator to obtain a molded product (cylindrical body) having a particle size of 5 to 20 mmφ and a length of 5 to 25 mm. Next, the molded product (grains) was carbonized and charged in an activation furnace, and steam was added in an amount of 0.5 to 1.5 ton / ton-active coke molded product (grains), so that the activation progressed, and 1000 A heated gas of ˜1100 ° C. is sent into the furnace, and the molded product (grains) is carbonized and activated at a temperature of 800 to 950 ° C. for a residence time in the furnace of 60 minutes to 180 minutes, and then cooled with a cooler. Thereafter, it is sieved into an active coke powder having a particle size smaller than a predetermined particle size and an active coke product having a particle size equal to or larger than a predetermined particle size by a sieving machine. An active coke containing mass% can be obtained.

In the present invention, the composition of the active coke is not particularly limited, but it is preferable that the composition of the active coke usually used in a moving bed type exhaust gas treatment process, for example, a dry desulfurization denitration process, For example, the volatile content is 2% by mass or more and the fixed carbon contains 87 to 94% by mass. The specific surface area is preferably 50 to 500 m ² / gr.

  In addition, the pulverization of semi-coke and caking coal is controlled to adjust the particle size of the raw material, or the distribution of the particle size of the raw material at the time of molding, or the disk pellet which is a compression granulator. In addition, the carbon particle filling rate of the granulated molded product is adjusted and the packing density of the surface layer portion is increased by changing the shape of the inlet side of the die hole of this disk pelleter or combining them. Thus, the active coke having a two-layer structure of the present invention which is difficult to break can be obtained.

Below, an example of the manufacturing method of the active coke which has a two-layer structure of this invention is demonstrated.
Semi-coke and caking coal were pulverized so that particles of 100 μm or less were 90% by mass or more to obtain raw material powder. As a molding method, compression molding is preferable to extrusion molding (for example, an extrusion granulator), and it is preferable to use, for example, a disk pelleter as the compression molding machine. This compression molding machine has a block body provided with a plurality of die holes on one end side of a cylindrical body, and a powder raw material is press-fitted from the other end side of the cylindrical body. Thereby, the active coke powder raw material is press-fitted into the die hole from one side (entry side) of the block body, and the activated coke formed from the other side (exit side) is pushed out.

  The shape of the die hole of this block body is usually a cylindrical shape with the same diameter from the entry side to the exit side, but in the present invention, the shape of the entry side of this die hole is a truncated cone shape that opens to the entry side, and from the middle The exit side was cylindrical. Furthermore, the conical surface of the truncated cone was formed into a curved truncated cone shape in which the axial direction of the cone (which is the raw material inflow direction) was a curved surface. When the die hole has such a shape, when the raw material powder is compressed and flows into the die hole, the stress is applied to the raw material powder near the raw material inflow portion (entrance side) and the wall surface of the curved cone of the die hole To be applied uniformly in the circumferential direction as well as in the radial direction. At this time, since the shape of the die hole is a curved cone shape as described above, the amount of compressive deformation of the raw material powder increases as the surface layer portion increases. As a result, the carbon particle filling rate of the formed active coke can be made high and dense in the surface layer portion and low in the center side (inner layer portion), and the active coke having a two-layer structure as in the present invention can be obtained. Can do.

  In addition, when the pulverized particle size of semi-coke and caking coal is 90% by mass or more as in the conventional case of 200 μm or less, one carbon particle is large. It is difficult to control the carbon particle filling rate. For this reason, it is preferable that the pulverized particle size be 90 μm or more when 100 μm or less. As described above, the pulverized particle size of the raw material powder is adjusted so that 100 μm or less is 90% by mass or more, the molding pressure is adjusted as compression molding, and the die having a curved truncated cone shape on the inlet side in compression molding. By combining the conditions such as the formation of pores, the active coke having a two-layer structure with different average carbon particle filling rate of the present invention can be produced.

Hereinafter, based on an Example, this invention is demonstrated concretely.
As coal for semi-coke, fixed carbon: 40% by mass, volatile component (VM): 35-48% by mass, ash: 10% by mass or less, crystal water: 6% by mass or less, and this is low-temperature carbonized Semi-coke (fixed carbon: 65% by mass or more, volatile component (VM): 15-25% by mass, ash: 10% by mass or less) and caking coal (fixed carbon: 65% by mass or more, Volatile component (VM): 15-25% by mass, ash: 10% by mass or less, crystal water: 2.5% by mass or less) and binding aid (tar or tar refined product) and semi-coke and caking property The pulverized particle size of coal and the blending ratio of semi-coke, caking coal, and binding aid were adjusted and mixed. This mixed raw material is formed (granulated) using a disk pelleter with the die shape and extrusion pressure adjusted (granulated), and the surface layer part, the carbon particle filling rate of the inner layer part, and the boundary position of the surface layer part and inner layer part are changed. (Grain). The molded product (grains) was charged into a carbonization / activation furnace, carbonized and activated at a predetermined temperature and time, and activated coke having a two-layer structure for exhaust gas desulfurization and denitration.
In the carbonization / activation furnace, activation was advanced by adding 1.0 to 1.2 tons of water vapor per ton of molded product (grains). Table 3 shows the production conditions of the activated coke of Examples 1 to 4 and Comparative Example 1.

The obtained active coke was measured for strength properties such as crushing strength and logger strength, in addition to structural properties such as carbon particle filling rate and Rm / Ri. In addition, the carbon particle filling rate was made into the average value of five in Examples 1-4 and Comparative Examples 1-3. These results are shown in Table 4.
In addition, a sulfuric acid strength test was performed in order to evaluate the durability of the activated coke, that is, the wear resistance. These characteristics were also confirmed for comparison in Comparative Examples 2 (conventional active coke (i)) and 3 (conventional active coke (ii)) of conventional active coke (single layer structure). .
In addition, carbon content of the obtained active coke of Examples 1-4 and the comparative example 1 is 88-94 mass%, a volatile matter is 0.8-3.3 mass%, and the comparative example 2 , 3 has a carbon content of 75 to 85% by mass and a volatile content of 1.2 to 3.2% by mass, both of which are normal levels, and the desulfurization and denitration function as an active coke is a problem. It was not.

  The crushing strength, the logger strength, the specific surface area, and the sulfuric acid strength test were performed according to the following methods.

<Crush strength>
As shown in FIG. 18, the crushing strength is measured by using a compressive strength measuring tester 6 (2000 model manufactured by Intesco), with the cylinder axis of the active coke (cylindrical body) 1 placed horizontally on the anvil 5, The maximum load W (kgf) at the time of compressive fracture was divided by the longitudinal cross-sectional area S = (diameter: D) × (length: L) of the active coke. The value was taken as the crushing strength.

<Loga strength>
As shown in FIG. 19, 30 g of active coke sample was placed in a rotating cylinder 9 (200 mmφ × 70 mm) in which two baffle plates 8 having a height of 30 mm were installed on the diagonal of the cylinder, and the motor 10 rotated at 50 rpm. The cylinder 9 was rotated 1000 times. Thereafter, the activated coke was taken out, fine powder was removed with a 3 mm sieve, and the weight ratio on the 3 mm sieve with respect to the input activated coke weight was determined.

<Specific surface area>
A powder sample obtained by grinding 2 g of an activated coke sample with agate is placed in a measurement cell (Monosorb: manufactured by Yuasa Ionix Co., Ltd.) and nitrogen streamed at 350 ° C. for 1 hour. The specific surface area was calculated by the BET single point method.

<Sulfuric acid strength test>
30 g of active coke was sampled and 1) this was immersed in a 60% by mass sulfuric acid solution at room temperature for 2 hours to adsorb sulfuric acid to the active coke. 2) The activated coke is lifted from the sulfuric acid solution and dried at 120 ° C. for 2 hours to remove moisture. 3) Next, this is maintained at 400 ° C. for 2 hours under a nitrogen atmosphere, and a regeneration treatment is performed to remove sulfuric acid. 4) The activated coke after the regeneration treatment is charged into the logger testing machine shown in FIG. 22 and rotated at 50 rpm for 20 minutes. 5) Thereafter, the activated coke is taken out, fine particles are removed with a 3 mm sieve, the weight on the remaining 3 mm sieve is measured, and 6) the weight ratio on the 3 mm sieve to the collected weight of 30 g is obtained as the residual ratio. 7) The test of 1) to 6) is repeated, and the durability is evaluated by repeating the test until the residual ratio becomes 0% by mass or close to 20% by mass. The greater the number of repetitions, the better the durability.

These activated cokes were used in a moving bed type dry desulfurization denitration apparatus for treating exhaust gas from a sinter production apparatus for iron making, and the monthly replenishment rate and average particle diameter were measured. The results are also shown in Table 4. Incidentally, the amount of exhaust gas treated during this period was 900,000 Nm ³ / Hr~100 ten thousand Nm ³ / Hr.

  Examples 1 to 4 are active cokes having a two-layer structure of the present invention, in which the boundary position between the surface layer part and the inner layer part is changed from the surface layer part to the inner layer part side. The active coke of Comparative Example 1 has a two-layer structure in which the boundary position is almost the same as that of Example 2, but shows an example in which the average carbon particle filling rate of the surface layer is less than 60%, and Comparative Examples 2 and 3 are conventional. 2 shows an example of an active coke having a single layer structure.

  That is, in Example 1, the boundary Rm / Ri between the surface layer portion and the inner layer portion is 0.86, and the average carbon particle filling rate is 62.7% for the surface layer portion and 57.6% for the inner layer portion, The surface layer portion is higher than the average carbon particle filling rate of 58.6%. The difference in the average carbon particle filling rate between the surface layer portion and the inner layer portion is 5.1%. Further, in Example 2, the boundary Rm / Ri between the surface layer part and the inner layer part is 0.76, and the boundary position is on the inner layer part side as compared with Example 1. The average carbon particle filling rate is 63.3% in the surface layer portion and 58.1% in the inner layer portion, and the surface layer portion is higher than the overall average carbon particle filling rate 60.1%. The difference in the average carbon particle filling rate between the surface layer portion and the inner layer portion is 5.2%. In Example 3, the boundary Rm / Ri between the surface layer part and the inner layer part is 0.54, and the boundary position is further on the inner layer part side compared to Examples 1 and 2. The average carbon particle filling rate is 63.4% in the surface layer portion and 57.8% in the inner layer portion, and the surface layer portion is higher than the total average carbon particle filling rate 61.7%. The difference in the average carbon particle filling rate between the surface layer portion and the inner layer portion is 5.6%.

  In Example 4, the boundary Rm / Ri between the surface layer portion and the inner layer portion is 0.76, which is the same as that in Example 2. The average carbon particle filling rate of the surface layer portion is 56.8% for the inner layer portion and 60 for the surface layer portion. .6% and the surface layer portion exceeds 60%, which is the active coke having the two-layer structure of the present invention as in Examples 1-3. In addition, the difference of the average carbon particle filling rate of the surface layer part of the surface layer part and the inner layer part is 3.8%. The average carbon particle filling rate of the surface layer portion of Example 4 is slightly lower than those of other Examples 1 to 3, and the difference in average carbon particle filling rate between the surface layer portion and the inner layer portion of the surface layer portion is also different from that of other examples. It is a little smaller than.

  Regarding the strength characteristics, the logger strength is not much different from the active coke of the comparative example 1 having a two-layer structure and the comparative examples 2 and 3 having a single-layer structure, but the crushing strength is an example having a two-layer structure. It turns out that the activated coke of 1-4 is remarkably excellent. Moreover, although the active coke of the comparative example 1 of 2 layer structure has high crushing strength compared with the comparative examples 2 and 3 of a single layer structure, it is low compared with 1-4 of the Example of this invention. This is apparent from the average particle diameter, and the active coke of Examples 1 to 4 according to the present invention is the active coke having the two-layer structure of Comparative Example 1 and the conventional active coke of Comparative Examples 2 and 3. It can be seen that the average particle size is larger than that, wear is small, and cracking is difficult. The activated coke of Comparative Example 1 having a two-layer structure also has a smaller average particle diameter than Examples 1 to 4, although the average particle diameter is larger than that of the single-layer structure. Moreover, it turns out that the monthly replenishment rate of Examples 1-4 is smaller than that of a comparative example, and is excellent in durability.

  FIG. 12 shows the use of the conventional activated coke (i) of Comparative Example 2 in Table 4 in the dry desulfurization denitration apparatus described above, and in the middle of Example 1, Example 2, Example 3, or Example 4 and comparison The change was made by replenishing the active coke of Example 1, and the change in the replenishment amount thereafter was investigated. The monthly replenishment rate and the cumulative replenishment rate are obtained based on the replenishment amounts of various active cokes obtained for each month, and the horizontal axis indicates the cumulative replenishment rate and the vertical axis indicates the monthly replenishment rate. The horizontal axis represents the cumulative replenishment rate, but means the time course after switching to various active cokes. Furthermore, it shows that the cumulative replenishment rate needs to be 100% or more in order for the monthly replenishment rate to be stable. As apparent from FIG. 12 and Table 4, when the active coke of the present invention (Examples 1 to 4) was used, compared to the active coke of Comparative Example 1 and Comparative Example 2 (conventional active coke (i)). It can be seen that the monthly replenishment rate is clearly lower and the cumulative replenishment rate is also lower. The monthly replenishment rate was determined as (monthly replenishment weight / total weight of activated coke in the desulfurization denitrification apparatus) × 100 (%). The cumulative replenishment rate was determined as (cumulative replenishment amount / total weight of activated coke of the desulfurization denitrification apparatus) × 100 (%).

  FIG. 13 shows the results of the sulfuric acid strength test when the active cokes of Examples 1 to 4 and Comparative Example 2 in Table 4 were used. As can be seen from FIG. 13, the active coke of the present invention of Examples 1 to 4 is more durable than the conventional active coke of Comparative Example 2 in the number of tests until the residual rate is close to 0%. You can see that

  14 (a) and 14 (b) show that the activated coke of the present invention of Examples 1 to 4 and the conventional activated coke (Comparative Example 2) as a comparative example are used in the above-mentioned dry desulfurization denitration process, and for a certain period of time. The particle number distribution of the active coke sampled later is shown. As can be seen from these figures, it is clear that the active coke having a two-layer structure according to the example of the present invention has a low particle number ratio and is hard to break compared with the conventional active coke.

  In the present invention, the active coke having a particle size (diameter) of about 9 mm has been described as an example. However, the present invention is not limited to this particle size, and a particle size (diameter) usually used is around 5 to 15 mm. Of course, it is needless to say that the effects of the present invention can be obtained by forming the same structure even in activated coke of 5 to 10 mm.

As described above, when the activated coke having a two-layer structure of the present invention is used in a moving bed type desulfurization / denitrification process, it is difficult to break, can maintain a large average particle diameter, and can reduce pressure loss. Moreover, it has the very outstanding characteristic that the replenishment amount can be reduced.
In order to improve the reactivity with exhaust gas on the surface of the active coke of the present invention, that is, the outer surface of the surface layer portion, and to improve the strength, a coating layer such as nanocarbon may be formed as the outermost layer portion, The effect of the active coke having the two-layer structure of the present invention is not impaired.

It is a schematic diagram which shows the cross section of the active coke of the 2 layer structure of this invention. It is a figure which shows the result of the analysis of the average particle diameter of active coke, Rm / Ri of the boundary position of a surface layer part and an inner layer part, and a wear rate. It is a figure which shows the relationship between a wear rate ratio and a maximum average particle diameter. It is a figure which shows the relationship between Rm / Ri of the optimal boundary position of the active coke of a two-layer structure, and a wear rate ratio. It is a schematic diagram of the cross section of the activated coke which shows the measuring method of the carbon particle filling rate in this invention. It is a figure which shows an example of the visual field image in the measuring method of the carbon particle filling rate of this invention, (a) is a real image, (b) is a binarized image. It is a figure which shows the relationship between the carbon particle filling ratio and strength characteristic (crushing strength) in this invention. It is a figure which shows the relationship between the carbon particle filling rate and wear rate ratio in this invention. It is a figure explaining the setting of the boundary position of the surface layer part and inner layer part in the active coke of the two-layer structure of this invention. It is a figure which shows the other example explaining the setting of the boundary position of the surface layer part and inner layer part in the active coke of the two-layer structure of this invention. It is a flow outline figure explaining an example of a manufacturing process of active coke of the present invention. It is a figure which shows the change of the replenishment rate of the active coke of this invention in a dry-type desulfurization denitration process. It is a figure which shows the result of the sulfuric-acid-strength test of the active coke of this invention. It is a figure which shows the particle number distribution of the active coke in a dry desulfurization denitration process, (a) is Example 1, 2 of this invention, (b) is activity of Example 3, 4 of this invention, and Comparative Example 2, respectively. The case of coke is shown. It is a figure which shows the particle size distribution (average particle diameter) of the conventional active coke. It is a figure which shows the particle number distribution of the conventional active coke. It is a figure which shows the relationship between the exhaust gas pressure loss and the average particle diameter in a desulfurization denitration process. It is a figure which shows the apparatus which measures the crushing strength of active coke. It is a figure which shows the apparatus which measures the logger strength of active coke.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Active coke 2 Surface layer part 3 Inner layer part 4 Boundary position 5 Anvil 6 Compressive strength measurement tester 7 Crosshead 8 Baffle plate 9 Rotating cylinder 10 Motor

Claims (3)

  An active coke used in a moving bed type exhaust gas treatment process manufactured using coal as a main raw material, the active coke having a surface layer portion with an average carbon particle filling rate of 60% or more, and an average carbon particle filling rate An active coke for an exhaust gas treatment process of a moving bed system characterized by having a two-layer structure having an inner layer portion of less than 60%.   2. The moving bed system according to claim 1, wherein a boundary between a surface layer portion and an inner layer portion of the active coke is in a range of 0.5 to 0.9 in a radius ratio Rm / Ri of the active coke. Active coke for exhaust gas treatment process. Where Rm is the radius of the inner layer portion of the activated coke and Ri is the radius of the activated coke.   The ratio of the average carbon particle filling rate of the surface layer part to the average carbon particle filling rate of the inner layer part of the active coke is 1.07 or more, The exhaust gas treatment of the moving bed system according to claim 1 or 2 Active coke for process.