JP2014040570A - Method of manufacturing coke for gasification melting furnace, and method of using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of economically and efficiently manufacturing a coke having excellent fire grate functions when used as a heat source for a gasification melting furnace.SOLUTION: The method of manufacturing a coke for a gasification melting furnace is a method of manufacturing a coke in a serial type molded coke manufacturing process, and includes a molding process of press-molding a raw material containing coal and a binder to obtain molded charcoal and a dry distillation process of dry distilling the molded charcoal by increasing a temperature with a vertical shaft furnace to obtain a coke for the gasification melting furnace having a collapse strength of 2500 N or more. An average rate of temperature increase between 600 to 700°C in the dry distillation process is above 0 and 5°C/min. or less.

Description

  The present invention relates to a method for producing coke for a gasification melting furnace and a method for using coke obtained by the production method.

  The blast furnace coke functions as a reducing material and a heat source, and also functions as a support for maintaining air permeability in the blast furnace, and is indispensable in the blast furnace ironmaking method. In this way, since blast furnace coke functions as a support, from the viewpoint of avoiding an increase in ventilation resistance in the blast furnace, it can easily crack or wear even in contact with hard materials such as iron ore. In order to prevent atomization, a material having a high drum strength (DI) is used.

  As a method for producing such blast furnace coke, a chamber furnace method and an FCP (Formed Coke Process) method are known. Among these, in the FCP method, coke is produced by dry distillation of coal obtained by blending coal and a binder such as pitch, asphalt, and tar and press molding. The FCP method tends to be difficult to obtain large coke because the raw coal is cracked or chipped as compared with the chamber furnace method. For this reason, as raw material coal, it is necessary to use caking coal as shown in patent document 1 in order to suppress breakage of cast coal.

  On the other hand, as a use of coke, in addition to a blast furnace, there is a gasification melting furnace for melting wastes. In such a gasification and melting furnace, a general waste, an industrial waste, or a processed product obtained by drying, incinerating, and pulverizing waste can be melted and recycled as slag and metal. As the coke used in such a gasification melting furnace, blast furnace coke is usually used.

  However, caking coal, the main raw material for blast furnace coke, has a limited production area and a limited amount of mining, and there are concerns that it will be depleted in the future. For this reason, a technique for reducing the amount of blast furnace coke used in a gasification melting furnace has been studied.

Japanese Patent No. 3491902

  However, with the conventional technology, it is difficult to sufficiently reduce the amount of blast furnace coke used as a heat source for a gasification melting furnace. In addition, although an alternative raw material for coke for blast furnace has been proposed, a material that can be mass-produced on an industrial scale has not yet been found. For this reason, it has been required to establish a technique for economically and efficiently producing a heat source for a gasification melting furnace.

  Under such circumstances, the present inventors have not simply improved the blast furnace coke used in the blast furnace, but developed a coke for gasification melting furnace that is suitable for the gasification melting furnace and is different from the blast furnace coke. Various studies were conducted as much as possible. The present invention has been made in view of the above circumstances, and economically and efficiently produces coke for a gasification melting furnace having an excellent grate function when used as a heat source for the gasification melting furnace. An object of the present invention is to provide a manufacturing method that can be used. Moreover, an object of this invention is to provide the usage method of the coke which has the outstanding economical efficiency.

  Since the coke for gasification melting furnace is thrown into a shaft furnace together with waste and used as a heat source, it is required to have an excellent grate function and reduce the coke unit. Therefore, the present inventors examined characteristics that coke should have in order to exhibit an excellent grate function. In order for the coke to exhibit an excellent grate function, it is preferable to have a size larger than that of ordinary blast furnace coke while having sufficient strength. As an index of the strength of blast furnace coke, the drum index is known as described above. The blast furnace coke needs to withstand the load of iron ore filled in the blast furnace because the height of the blast furnace is high.

  However, paying attention to the use of gasification melting furnace coke, the waste contacted with the gasification melting furnace coke tends to be lighter and softer than the iron ore with which the blast furnace coke contacts. For this reason, the gasification melting furnace coke is not required to be as wear resistant as the blast furnace coke. Here, since the drum index is a characteristic that is influenced not only by strength but also by wear, when used as an index of coke for a gasification melting furnace, there is a possibility of over-spec, which is economical and efficient. From the viewpoint of producing coke for a gasification melting furnace, it can be said that the index is not suitable.

  Based on the above-mentioned knowledge, the present inventors use the crushing strength as an index of the strength of the coke for the gasification melting furnace, not the drum index, and have an excellent grate function suitable for use in the gasification melting furnace. A method for economically and efficiently producing coke for a gasification melting furnace having the present invention was studied. As a result, the present inventors have found a method for producing coke that is particularly suitable for a gasification melting furnace without using caking coal as a raw material.

  That is, the present invention is a method for producing coke by a continuous molding coke manufacturing process, in which a molding process for obtaining molding coal by pressure molding a raw material containing coal and a binder, And a carbonization step of obtaining a coke for gasification melting furnace having a crushing strength of 2500 N or more, and having an average value of the temperature increase rate between 600 and 700 ° C. in the carbonization step A method for producing coke for a gasification melting furnace that exceeds 0 and is 5 ° C./min or less is provided.

  According to the method for producing coke for a gasification melting furnace of the present invention, it is possible to economically and efficiently produce coke for gasification melting furnace having an excellent grate function without using caking coal as a raw material. Can do. The reason for this is as follows. That is, in this invention, while using coal not limited to caking coal as a raw material, the continuous type | mold coke manufacturing process method conventionally known as a manufacturing method of coke for blast furnaces is employ | adopted. Here, conventionally, caking coal is indispensable for producing coke having high drum strength, and the continuous molding coke production process method was considered unsuitable for producing large-sized coke. .

  However, in this invention, the cracking of the forming coal in a dry distillation process can be suppressed by making the average value of the temperature increase rate between 600-700 degreeC in a dry distillation process into 5 degrees C / min or less. . Thereby, the coke for gasification melting furnace which has a large size with a high yield can be obtained. The reason why cracking is suppressed by reducing the temperature rising rate between 600 and 700 ° C. in this way is that the carbon-carbon polymerization reaction proceeds in this temperature range. This is thought to be because the shrinkage of the abruptly progresses and cracks are easily induced.

  Moreover, since the crushing strength is employed as an index for maintaining the grate function when used in a gasification melting furnace, it is possible to avoid excessive quality related to the strength of coke. Accordingly, even when coal not limited to caking coal is used as a raw material in the continuous molding coke manufacturing process method, coke suitable for a gasification melting furnace can be manufactured with a high yield.

  The gasification melting furnace coke production method of the present invention uses coal not limited to caking coal as a raw material, and can produce gasification melting furnace coke with a high yield. . Moreover, since the continuous molding coke manufacturing process is adopted, the coke for the gasification melting furnace can be efficiently manufactured. And since the obtained coke for gasification melting furnaces has the crushing strength more than predetermined value, it can exhibit the grate function excellent in the gasification melting furnace. That is, according to the present invention, when used as a heat source for a gasification melting furnace, coke having an excellent grate function can be produced economically and efficiently.

  In the method for producing coke for a gasification melting furnace of the present invention, the coal in the molding step is preferably composed only of non-caking coal. As a result, the method for producing coke for a gasification melting furnace is further improved in economic efficiency.

  In the method for producing a coke for a gasification melting furnace according to the present invention, it is preferable that the average particle diameter of the coal coal in the dry distillation step is 60 mm or more. When such a large size coal was used in the continuous molding coke manufacturing process, it was considered that the yield was reduced due to breakage in the dry distillation process. However, in this invention, since the temperature increase rate between 600-700 degreeC is fully reduced, even if it uses a large sized coal, the fall of the yield by the crack of a coal can be suppressed. . Thus, coke for a gasification melting furnace having a more excellent grate function can be produced with a high yield.

  In the method for producing a coke for a gasification melting furnace according to the present invention, the top temperature of the vertical shaft furnace is preferably 250 to 400 ° C. The initial rate of temperature rise when the charcoal is introduced into the vertical shaft is adjusted by the top temperature of the vertical shaft furnace. By setting the top temperature to 250 ° C. or higher, the coal is rapidly heated to form a hard outer shell. As a result, when the temperature further rises and softens and melts, it is possible to sufficiently prevent the coals from being fused or from being crushed. On the other hand, when the top temperature exceeds 400 ° C., the temperature is rapidly increased to a temperature region where the coal coal expands, and therefore, blistering cracks tend to occur. From these factors, if the temperature of the top portion of the vertical shaft furnace is 250 to 400 ° C., the yield of coke for the gasification melting furnace can be further increased.

In the method for producing a coke for a gasification melting furnace according to the present invention, the vertical shaft furnace has a plurality of tuyere for introducing gases having different temperatures into the furnace, of which the temperature is The temperature at the highest gas tuyere is preferably 850-950 ° C. In this way, the vertical shaft furnace has a plurality of tuyere that introduce gases having different temperatures from each other, whereby the heating rate of the coal can be controlled according to the temperature. The higher the heating temperature in the carbonization process, the greater the strength of the coke. However, when the maximum heating temperature exceeds 950 ° C., coke gasification reaction occurs due to the oxidizing components (H ₂ O, CO ₂ ) contained in the furnace gas, the coke yield decreases, and the strength increases. It tends to decrease. Therefore, the temperature at the tuyeres of the gas with the highest temperature is set to 850 to 950 ° C., and the maximum temperature in the vertical shaft furnace is adjusted to the temperature range, thereby increasing the coke for the gasification melting furnace having high crushing strength. It can be manufactured with yield.

  The present invention also introduces the gasification melting furnace coke and waste obtained by the above-described manufacturing method into the gasification melting furnace, heats the waste using the gasification melting furnace coke as a heat source, and Provided is a method for using coke having a melting step. The method of using coke of the present invention uses coal that is not limited to caking coal as a raw material, and heats and melts waste using coke produced at a high yield. And this coke can exhibit a sufficient grate function in a gasification melting furnace. Therefore, the method for using the coke of the present invention is more economical than the method using the conventional blast furnace coke.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the coke for gasification melting furnaces which can manufacture the coke which has the excellent grate function when used as a heat source for gasification melting furnaces economically and efficiently Can be provided. Moreover, according to this invention, the usage method of the coke which has the outstanding economical efficiency can be provided.

It is a schematic diagram which shows the outline | summary of the continuous type | mold coke manufacturing equipment used for suitable embodiment of the manufacturing method of the coke for gasification melting furnaces of this invention. It is a schematic diagram which shows the outline | summary and temperature gradient of a vertical shaft furnace in suitable embodiment of the manufacturing method of the coke for gasification melting furnaces of this invention. It is a schematic diagram which shows the temperature increase rate of the dry distillation process in suitable embodiment of the manufacturing method of the coke for gasification melting furnaces of this invention. It is a schematic diagram of the measuring apparatus used for the measurement of the crushing strength of the coke for gasification melting furnaces. When the coke for gasification melting furnace obtained by the method for producing coke for gasification melting furnace of the present invention is used in the gasification melting furnace, the size of the coke for gasification melting furnace and the melt of the gasification melting furnace It is a graph which shows the relationship with temperature. It is a schematic diagram which shows the outline | summary of the gasification melting equipment used for suitable embodiment of the usage method of the coke for gasification melting furnaces of this invention. It is a figure which shows the relationship between the highest temperature at the time of manufacturing coke in Examples 1-3 and the comparative example 1, and the crushing strength of the manufactured coke. It is a graph which shows the temperature rising pattern at the time of manufacturing coke in Examples 1-3 and Comparative Example 1. FIG. It is a figure which shows the relationship between the maximum temperature at the time of manufacturing coke in Examples 4-6 and Comparative Example 2, and the crushing strength of the manufactured coke. It is a graph which shows the temperature rising pattern at the time of manufacturing coke in Examples 4-6 and Comparative Example 2. It is a graph which shows the temperature rising pattern at the time of manufacturing coke in Examples 7, 8, and 9. It is a graph which shows the temperature rising pattern at the time of manufacturing coke in Examples 10-15. It is a graph which shows the crushing strength of the coke of Examples 10-15 and Comparative Examples 3-5.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted. Further, the positional relationship such as up, down, left and right is based on the positional relationship shown in the drawings unless otherwise specified. Further, the dimensional ratios in the drawings are not limited to the illustrated ratios.

  The manufacturing method of the coke for gasification melting furnace of this embodiment is a manufacturing method of the coke for gasification melting furnace using the continuous type | mold coke manufacturing process. This manufacturing method includes a molding step of pressure-molding a raw material containing coal and a binder to obtain a coal, and heating the coal using a vertical shaft furnace to dry distillation to coke for a gasification melting furnace. A carbonization step to obtain

  FIG. 1 is a schematic diagram showing an outline of a continuous molding coke production facility used in a method for producing a coke for a gasification melting furnace which is a preferred embodiment of the present invention. 1 is provided on the downstream side of the coal-forming unit 10 and the coal-forming unit 10 for producing the coal by press-molding a raw material containing coal and a binder. And a carbonization section 20 for producing carbonized coke for a gasification melting furnace by carbonizing carbon. Using such a continuous molded coke manufacturing facility 100, the method for manufacturing a coke for a gasification melting furnace according to this embodiment can be implemented.

  In the molding process, first, coal and a binder are prepared. As coal, it is preferable to reduce the ratio of caking coal from a viewpoint of cost reduction, and it is more preferable to use only caking coal without using caking coal at all. As the non-caking coal, one having a crucible expansion index of 3 or less is used from the viewpoint of cost reduction of raw materials and securing of availability. This crucible expansion index is measured according to “Crucible expansion index test method” of JIS M8801. Non-caking coal is introduced from the tank 11 into the primary pulverizer 12 and pulverized, and then introduced into the dryer 13. Here, it is preferable to reduce the moisture contained in the non-coking coal to 2-3 mass%. The non-caking coal dried by the dryer 13 is pulverized and atomized by the secondary pulverizer 14.

  The binder has a function of binding granular non-caking coal, and normal coal tar, petroleum pitch, coal pitch, soft pitch, polyvinyl alcohol, petroleum asphalt, waste oil, and the like can be used. Non-caking coal, a binder, and hot water as necessary are kneaded by a kneader 15 to prepare a raw material for the forming coal. For example, when soft pitch (SOP) is used as the binder, the blending ratio of non-caking coal and SOP is 4 to 8% in mass ratio of non-caking coal based on the total of non-caking coal and SOP. It is preferable.

  The raw material preferably does not contain coal having a crucible expansion index exceeding 3 from the viewpoint of reducing raw material costs. The raw material may contain powdered coke derived from coal, dust collection, or char. As the powder coke and dust collection, for example, those produced in a general coke oven can be used. Char is heat-treated (dry-distilled) of coal such as subbituminous coal and lignite having high ignitability in order to suppress ignitability.

The raw material prepared by the kneading machine 15 is introduced into the molding machine 16 and subjected to pressure molding to produce a plurality of molded charcoal. As the molding machine 16, a double roll molding machine can be used. The pressure molding of the raw material is preferably performed by pressurizing to a linear pressure of 10 to 100 kN / cm. The coal thus produced is once stored in the tank 17. The average particle size of the coal is preferably 60 mm or more. The average particle diameter here is an arithmetic average value of the particle diameter A ₁ [mm] calculated by the following formula (1) on the assumption that the volume V ₁ [ml] of the coal is a sphere having the same volume.
A ₁ = 2 × ((V ₁ × 3/4 / π) ^1/3 ) × 10 (1)

  In this embodiment, since the temperature rising rate in the carbonization step described later is controlled within a specific range, even if using large coal as described above, it is sufficient to break down and chip into small particles. Can be suppressed. Only the coal having a predetermined size or more may be transferred to the dry distillation section 20 as the coal char of the tank 17 produced in the molding process. In this case, those smaller than a predetermined size may be returned to the kneader 15 via a return pipe. The shape of the charcoal is not particularly limited, and may be a Macek type, for example. If the charcoal has a shape that can reduce the temperature difference between the surface portion and the center portion, the occurrence of cracking due to thermal stress can be further reduced in the dry distillation step described later.

  In the carbonization process, the charcoal produced in the molding process is introduced from the top of the carbonization furnace 21 which is a vertical shaft furnace, and the temperature is raised by contacting with the heated gas.

  FIG. 2 is a schematic diagram showing an outline of the dry distillation furnace 21 in the continuous molded coke manufacturing facility 100 and a temperature gradient inside thereof. The dry distillation furnace 21 has a first tuyere 21a that supplies a first heating gas for heating the coal to the inside of the dry distillation furnace 21, and is lower than the first tuyere 21a and higher than the first heating gas. And a second tuyere 21b for supplying a second heated gas having a temperature. The temperature of the first heating gas when the first heating gas is introduced into the dry distillation furnace 21 from the first tuyere 21a, that is, the introduction temperature of the first heating gas is preferably 600 to 700 ° C. The temperature of the second heating gas when the second heating gas is introduced into the dry distillation furnace 21 from the second tuyere 21b, that is, the introduction temperature of the second heating gas is preferably 850 to 1000 ° C., and more Preferably it is 850-950 degreeC. Thus, since the carbonization furnace 21 has a plurality of tuyere for introducing the first heating gas and the second heating gas having different temperatures from each other, the heating rate of the forming coal can be accurately adjusted. Can do.

  The dry distillation furnace 21 has a gas extraction port 21c below the second tuyere 21b. The gas extracted from the gas extraction port 21c by the ejector 25 is integrated with the gas that drives the ejector 25 and becomes the first heating gas. The dry distillation furnace 21 has a cooling gas introduction port 21d for introducing a cooling gas for cooling coke generated by dry distillation, below the gas extraction port 21c. The temperature of the cooling gas introduced from the cooling gas inlet 21d, that is, the introduction temperature of the cooling gas is preferably 20 to 60 ° C. That is, the dry distillation furnace 21 is provided with a first tuyere 21a, a second tuyere 21b, a gas extraction port 21c, and a cooling gas introduction port 21d sequentially from the top to the bottom.

  A region above the first tuyere 21 a of the dry distillation furnace 21 is a first heating region A. In the process of descending the first heating region A, the coal is heated to the vicinity of the introduction temperature of the first heating gas. A region between the first tuyere 21 a and the second tuyere 21 b of the dry distillation furnace 21 is a second heating region B. The forming coal heated to the vicinity of the introduction temperature of the first heating gas in the first heating region A is heated to the vicinity of the introduction temperature of the second heating gas in the process of descending the second heating region B. . By changing the introduction temperature of the first heating gas and the second heating gas, it is possible to adjust the heating rate of the forming coal in the dry distillation furnace 21.

  A curve x in FIG. 2 indicates the temperature of the forming coal, and curves y and z indicate the temperature of the gas in the dry distillation furnace 21. The temperature of the coal in this specification refers to the temperature at the center of the coal. Such temperature can be measured by inserting a thermocouple into the coal and placing the tip of the thermocouple at the center of the coal. As shown in FIG. 2, when the temperature of the coal is raised, the curve x indicating the temperature of the coal tends to be slightly lower than the curve y indicating the gas temperature. On the other hand, when the temperature of the coal is lowered, the curve x indicating the temperature of the coal tends to be slightly higher than the curve z indicating the gas temperature.

  When the charcoal is introduced from the top of the carbonization furnace 21, the charcoal comes into countercurrent contact with the heated gas rising in the carbonization furnace 21. Thereby, the temperature rise of the coal is started. The heating temperature at the beginning of the introduction of the charcoal can be adjusted by changing the temperature at the top of the dry distillation furnace 21. The temperature at the top of the dry distillation furnace 21 is preferably 450 ° C. or lower, more preferably 250 to 400 ° C. By setting it as such a temperature range, the cracking by the expansion | swelling and shrinkage | contraction of the coal is suppressed, and the collapse of the coal due to insufficient caking can be sufficiently suppressed.

  In the present embodiment, the temperature rising rate when the coal coal is heated from 600 ° C. to 700 ° C. in the dry distillation furnace 21 is set to a predetermined range. Specifically, the average value of the heating rate when the coal is heated from 600 ° C. to 700 ° C. exceeds 0 and is 5 ° C./min or less. By setting it as such a temperature increase rate, the crack which arises by shrinkage | contraction accompanying the polymerization reaction of carbon can fully be reduced.

The upper limit of the average value of the heating rate when the temperature of the coal is raised from 600 ° C. to 700 ° C. is preferably 3 ° C./min from the viewpoint of more reliably suppressing the failure of the coal. Preferably, it is 2 ° C./min. In addition, the lower limit of the average value of the heating rate is preferably 0.1 ° C./min, more preferably 1 ° C./min, from the viewpoint of more efficiently producing gasification melting furnace coke. In this specification, for example, the average value of the rate of temperature increase when the temperature is increased from T ₁ ° C to T ₂ ° C is obtained by increasing the temperature difference (T ₂ -T ₁ ) between T ₁ ° C and T ₂ ° C. It can be obtained by dividing by the time (minutes) required for heating.

  It is not essential to adjust the rate of temperature increase when the temperature of the coal is raised to 600 ° C and from 700 ° C. In the temperature range of 500 to 800 ° C., the shrinkage of semi-coke tends to occur. In particular, when the volume of the coal is large, cracks are likely to occur during shrinkage. Therefore, the upper limit of the average value of the heating rate when the temperature is raised from 500 ° C. to 800 ° C. is preferably 3 ° C./min from the viewpoint of obtaining a coal having higher strength. However, the lower limit of the average value of the heating rate when raising the temperature from 500 ° C. to 800 ° C. is preferably 0.1 ° C./min in order to avoid that the residence time of the coal becomes too long. Preferably it is 1 degree-C / min.

  From the viewpoint of producing gasification melting furnace coke having a higher crushing strength with a higher yield, the average value of the heating rate when the temperature of the coal is raised from 200 ° C. to 400 ° C. is preferably 0. Exceeding 25 ° C./min. From the same viewpoint, the average value of the heating rate when the temperature of the coal is raised from 400 ° C. to 500 ° C. is preferably more than 0 and not more than 10 ° C./min. From the same viewpoint, the average value of the heating rate when the temperature of the coal is raised from 800 ° C. to the maximum temperature is preferably more than 0 and 10 ° C./min or less.

  The temperature of the forming coal reaches the maximum temperature in the vicinity of the second tuyere 21b of the dry distillation furnace 21. This maximum temperature is substantially equal to the introduction temperature of the second heated gas. In this way, coking coal is produced and coke is produced. The higher the maximum temperature of the coal, the higher the coke strength. Therefore, the maximum temperature of the coal coal during dry distillation is preferably 850 to 1000 ° C. On the other hand, when there is a lot of moisture contained in the second heated gas, when the temperature of the second heated gas reaches 950 ° C. or higher, the moisture and carbon in the coke react and the generated coke tends to gasify. It is in. When coke is gasified, the strength of the coke is reduced and the yield is also reduced. For this reason, the maximum temperature of the coal is more preferably 850 to 950 ° C. However, this is not the case when the moisture contained in the second heated gas is small.

  The produced coke moves down the dry distillation furnace 21 and descends in the cooling region C. In the cooling region C, the coke is counter-contacted with the cooling gas introduced from the cooling gas inlet 21d and cooled to about 50 to 150 ° C. The cooled coke is taken out from the bottom of the dry distillation furnace 21. Thus, coke suitable for a gasification melting furnace can be obtained.

  FIG. 3 is a graph showing the relationship between the carbonization time and the carbonization temperature in the carbonization step of the gasification melting furnace coke manufacturing method of the present embodiment. In FIG. 3, the solid line indicates the temperature near the center of the coal or coke staying in the dry distillation furnace 21, and the dotted line indicates the temperature inside the dry distillation furnace 21. The coal coal introduced into the dry distillation furnace 21 from the top of the dry distillation furnace 21 comes into contact with the gas rising in the dry distillation furnace 21 and the temperature rise is started. After the coal is introduced, the coal is gradually raised in the dry distillation furnace 21 by descending. The initial temperature increase rate is, for example, 5 to 25 ° C./min. Thereafter, the rate of temperature rise of the charcoal gradually decreases as it approaches the first tuyere 21a.

  While heating the coal to 600-700 ° C. (region P in FIG. 3), the rate of temperature increase is in the range of more than 0 and 5 ° C./min, preferably more than 0 and 3 ° C./min. The range. Thereafter, the coal formed after passing through the position of the first tuyere 21a is further heated. The heating rate at this time is, for example, 3 to 10 ° C./min. The maximum temperature is reached when the charcoal reaches the second tuyere 21b. The produced coke is then cooled and taken out from the dry distillation furnace 21. The coke thus obtained is used as coke for a gasification melting furnace. The residence time of the coal and coke in the dry distillation furnace 21 is, for example, 5 to 10 hours.

  The coke for gasification melting furnace obtained by the production method of the present embodiment has a sufficiently large size since cracking during the dry distillation process is prevented. The coke for the gasification melting furnace has a crushing strength of 2500 or more, preferably 3000 N or more. Although the upper limit of crushing strength is not specifically limited, For example, it is 10,000N. The coke for gasification melting furnace obtained by the production method of the present embodiment has a high grate function when used as coke for the gasification melting furnace and functions as an excellent heat source.

The crushing strength in this specification is measured by the following procedure using the measuring apparatus 60 shown in FIG. First, the coke is exposed to air at 1000 ° C. for 30 minutes. Thereafter, the coke is cooled to room temperature in an N ₂ atmosphere. After cooling, in the measuring device 60 of FIG. 4, a coke 66 as a measurement target is placed on a movable plate 64 placed on a hydraulic jack 62 capable of measuring a pressurized pressure. Then, the movable plate 64 is moved upward by extending the cylinder of the hydraulic jack 62 upward. As a result, the coke 66 is sandwiched between the movable plate 64 and the fixed plate 68 fixed above the movable plate 64. The coke 66 is loaded and finally destroyed. The crushing strength is determined from the load at the time of failure.

  On the other hand, the drum strength that has been conventionally used as a strength evaluation method for blast furnace coke is that coke with a particle size of 50 mm or more is put in the drum, rotated for a predetermined time at a predetermined rotation speed, and then remains on the 15 mm sieve. As a percentage (% by weight). Since this strength is a numerical value affected by wear due to collision with the drum, it is not suitable as an index for evaluating suitability as a heat source in a gasification melting furnace. In the method for producing a coke for a gasification melting furnace according to the present embodiment, a coke having a crushing strength of 2500 N or more is produced. Therefore, when used as a heat source in the gasification melting furnace, an excellent grate function is exhibited. be able to.

  As a gas used as a heat source or a cooling medium in the dry distillation process, a gas generated in the dry distillation process (COG) is circulated and used. Such a gas is circulated and used by a gas circulation facility provided in the dry distillation section 20. That is, the gas discharged from the top of the dry distillation furnace 21 is introduced into a tar recovery facility 22 including a sensible heat recovery device 22a and a gas cooler 22b. The tar recovery facility 22 purifies the gas by removing moisture contained in the gas and light fractions of tar and pitch. The refined gas is reintroduced into the dry distillation furnace 21 by a circulation facility and is circulated for use. The circulation facility is provided with a heat storage furnace 23 and a heat exchanger 24. A part of the purified gas is heated to, for example, 850 to 1000 ° C. in the heat storage furnace 23, and then introduced into the dry distillation furnace 21 from the second tuyere 21 b as the second heating gas. Further, another part of the generated gas is heated to, for example, 500 to 600 ° C. in the heat exchanger 24 and then becomes a driving gas for the ejector 25. This gas is integrated with the gas extracted from the gas extraction port 21c of the dry distillation furnace 21 in the ejector 25 and becomes the first heating gas. This first heated gas is introduced into the dry distillation furnace 21 from the first tuyere 21a.

The coke for gasification melting furnace manufactured by this embodiment is used suitably as a heat source of a normal gasification melting furnace. Since the coke for gasification melting furnace functions as a heat source, it preferably has a large size. From such a viewpoint, the lower limit of the average particle size of the gasification melting furnace coke is preferably 50 mm or more, and more preferably 60 mm or more. Moreover, the upper limit of the average particle diameter of the gasification melting furnace coke is, for example, less than 120 mm from the practical viewpoint such as the ease of handling. The average particle diameter here is an arithmetic average of the particle diameter A ₂ [mm] calculated by the following formula (2) on the assumption that the volume V ₂ [ml] of the gasification melting furnace coke is a sphere having the same volume. Value.
A ₂ = 2 × ((V ₂ × 3/4 / π) 1/3) × 10 (2)

  FIG. 5 is a graph showing the relationship between the average particle size of coke and the melt temperature in the gasification melting furnace when coke is used for the gasification melting furnace. FIG. 5 shows that the melt temperature increases as the average particle size of the coke increases. That is, coke having a large size is suitably used as a heat source for a gasification melting furnace. In addition, the average particle diameter of the coke in FIG. 5 is an arithmetic average value of the diameter when coke is converted into a sphere having the same volume.

  The shape of the coke for the gasification melting furnace is not particularly limited, and may be spherical or a rectangular parallelepiped shape. This shape can be adjusted by changing the shape of the charcoal obtained in the molding process.

  FIG. 6 is a diagram schematically showing a gasification melting furnace for melting waste. Coke produced by the above-described continuous molding coke production process has an excellent crushing function because it has a high crushing strength. Further, since it can be produced more economically and efficiently than coke for blast furnace, it is preferably used as coke for gasification melting furnace as shown in FIG.

  The gasification melting equipment 200 includes a gasification melting furnace 40 and a charging device 50 provided on the upper portion of the gasification melting furnace 40. The gasification melting furnace 40 includes a shaft portion 42, a morning glory portion 44 provided at the lower end of the shaft portion 42, and a furnace bottom portion 46 provided at a lower portion of the morning glory portion 44. In the furnace bottom portion 46, an upper tuyere 45 for a pyrolysis zone and a lower tuyere 47 for a combustion melting zone are provided in order from the top. Each of the upper tuyere 45 and the lower tuyere 47 may have a plurality of stages.

  Coke, waste, and limestone as a basicity adjusting agent for the gasification melting furnace are introduced into the gasification melting furnace 40 by the charging device 50. In this way, coke, waste and limestone are introduced into the gasification melting furnace 40. The waste used here is general waste / industrial waste, or processed products obtained by subjecting them to drying, incineration, crushing, etc., and once they have been landfilled, they are re-digged again. Landfill waste including

  From the lower tuyere 47, oxygen or oxygen-enriched air is supplied, and from the upper tuyere 45, air is supplied as a combustion support gas. The coke 41 disposed in the lower part of the gasification melting furnace 40 is burned by oxygen or oxygen-enriched air supplied from the lower tuyere 47 and functions as a heat source. The coke 41 has a good grate function. The waste 48 disposed in the upper part of the gasification melting furnace 40 is heated by the combustion of coke and becomes a pyrolysis residue 43. The pyrolysis residue 43 is combusted mainly by air supplied from the upper tuyere 45.

  Inside the gasification melting furnace 40, a temperature gradient is generated by the combustion of the coke 41 and the like. Specifically, the gasification melting furnace 40 includes a drying / pre-tropical zone 40a (about 300 to 400 ° C.), a pyrolysis zone 40b (about 600 to 800 ° C.), and a combustion / melting zone 40c (from the top to the bottom). About 1000-1800 ° C.). The waste 48 introduced into the gasification melting furnace 40 passes through the dry / pre-tropical zone 40a, the pyrolysis zone 40b, and the combustion / melting zone 40c in this order. As a result, the combustible matter in the waste 48 is pyrolyzed and gasified and introduced into the combustion chamber, and the ash is converted into a melt through the pyrolysis residue 43. The melt containing slag and metal is discharged from a tap 49 provided in the furnace bottom 46.

  The pyrolysis gas generated in the gasification melting furnace 40 ascends the shaft portion 42 and is introduced into the combustion chamber from the exhaust gas pipe 52 connected to the lower portion of the charging device 50. The combustion exhaust gas is burned as a combustible gas, and then waste heat is recovered by a boiler. Thereafter, the temperature of the exhaust gas is adjusted in the temperature reducing tower, then passes through the dust collector and the catalytic reaction tower, and is discharged from the chimney.

  In the gasification melting equipment 200, waste is processed using the coke for gasification melting furnace manufactured by the above-described manufacturing method as a heat source. Since this gasification melting furnace coke can stably form a grate at the furnace bottom 46, the waste can be efficiently thermally decomposed and melted.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment.

  The contents of the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[Coke production]
Example 1
As raw materials, non-caking coal (crucible expansion index: 2.5) and a binder (SOP) were prepared. These raw materials and water were blended and kneaded and pressure-molded at 40 kN / cm using a double roll molding machine to produce a plurality of molding charcoal. The blending ratio (mass basis) of non-caking coal and binder was non-caking coal: binder = 100: 8. The average particle size of the produced coal was 60 mm. The produced coal was heated in a batch-type electric furnace capable of controlling the rate of temperature rise and subjected to dry distillation, and the reaction when the coal was introduced into the dry distillation furnace and subjected to dry distillation was simulated. In this way, coke equivalent to coke obtained in a dry distillation furnace as shown in FIG. 1 was produced.

  The initial temperature during dry distillation was 10 ° C., the maximum temperature during dry distillation was 1000 ° C., and the average value of the rate of temperature increase from the initial temperature to the maximum temperature was 1.67 ° C./min. Nitrogen gas was used as the gas to be introduced into the electric furnace that was considered as a carbonization furnace. The operating conditions in the carbonization process are as shown in Table 1. In this way, coke of Example 1 was obtained.

(Examples 2 to 6, Comparative Examples 1 and 2)
Examples 2 to 6 and the comparison were made in the same manner as in Example 1 except that the initial temperature and the maximum temperature when carbonizing coal in the carbonization furnace were changed as shown in Tables 1 and 2 and FIGS. Coke of Examples 1 and 2 was obtained.

[Characteristics and yield of coke]
In each of the examples and comparative examples, coke yield and crushing strength were determined. The yield of coke was determined as the mass ratio of the obtained coke to the total mass of the input coal. The crushing strength of the obtained coke was measured by the above-described procedure using the measuring apparatus shown in FIG. Tables 1 and 2 show the coke yield and crushing strength. Table 1 shows the influence of the maximum temperature, and Table 2 shows the influence of the initial temperature (furnace top temperature).

  FIG. 7 is a diagram showing the relationship between the maximum temperature when coke is produced in Examples 1 to 3 and Comparative Example 1 and the crushing strength of the produced coke. The crushing strength can be increased by increasing the maximum temperature at which coke is produced by dry distillation. FIG. 8 is a graph showing temperature rising patterns when coke is produced in Examples 1 to 3 and Comparative Example 1.

  FIG. 9 is a diagram showing the relationship between the initial temperature when coke is produced in Examples 4 to 6 and Comparative Example 2 and the crushing strength of the produced coke. If the initial temperature at the time of producing coke is too high, the crushing strength is lowered. FIG. 10 is a graph showing temperature rising patterns when coke is produced in Examples 4 to 6 and Comparative Example 2.

(Example 7)
Table 3 shows the initial temperature and maximum temperature when carbonizing coal in a carbonization furnace, and the average value of the heating rate of the coal is 0.5 ° C / min only between 600 and 700 ° C. The coke of Example 7 was obtained in the same manner as in Example 1 except that the average value of the heating rate in other temperature ranges was 1.5 ° C./min. Then, the crushing strength of the coke of Example 7 was measured in the same manner as in Example 1. The crushing strength of this coke is shown in Table 3.

(Example 8)
The initial temperature and the maximum temperature when carbonizing coal in a carbonization furnace were as shown in Table 3, and the average value of the heating rate of the coal was 0.5 ° C / min only between 500 and 600 ° C. The coke of Example 8 was obtained in the same manner as in Example 1 except that the average value of the heating rate in other temperature ranges was 1.5 ° C./min. Then, the crushing strength of the coke of Example 8 was measured in the same manner as in Example 1. The crushing strength of this coke is shown in Table 3.

Example 9
The initial temperature and the maximum temperature when carbonizing coal in a carbonization furnace are as shown in Table 3, and the average value of the heating rate of the coal is 0.5 ° C / min only between 700 and 800 ° C. The coke of Example 9 was obtained in the same manner as in Example 1 except that the average value of the heating rate in other temperature ranges was 1.5 ° C./min. Then, the crushing strength of the coke of Example 9 was measured in the same manner as in Example 1. The crushing strength of this coke is shown in Table 3.

  FIG. 11 is a graph showing a temperature rising pattern when producing cokes of Examples 7 to 9. Lines 1, 2, and 3 schematically show changes in the temperature of the formed coal in Examples 7, 8, and 9, respectively. From the results of Examples 7 to 9 shown in Table 3, it was confirmed that the crushing strength of the coke was further improved by reducing the heating rate at 600 to 700 ° C.

(Example 10)
Coking charcoal was produced in the same manner as in Example 1 and heated in an electric furnace for dry distillation. The initial temperature during dry distillation is 10 ° C., the maximum temperature during dry distillation is 900 ° C., the rate of temperature increase from the initial temperature to 300 ° C. is 6 ° C./min, the rate of temperature increase from 300 to 600 ° C. is 3 ° C./min, 600 The carbonization was dry-distilled at a rate of temperature increase up to -700 ° C at 0.5 ° C / min and a rate of temperature increase at 700-900 ° C at 3 ° C / min. Nitrogen gas was used as the gas to be introduced into the electric furnace that was considered as a carbonization furnace. The crush strength of the coke of Example 10 was measured in the same manner as in Example 1. The crush strength of the coke is shown in Table 4 together with the rate of temperature rise.

(Examples 11-15 and Comparative Examples 3-5)
Except that the rate of temperature increase at 600 to 700 ° C. during dry distillation was changed as shown in Table 4, dry distillation was performed in the same manner as in Example 10 to produce cokes of Examples 11 to 15 and Comparative Example 3. . Moreover, except having changed the temperature increase rate of 600-700 degreeC and 700-900 degreeC at the time of dry distillation as shown in Table 4, it carried out similarly to Example 10, and produced the coke of the comparative example 4. . Moreover, except having changed the temperature increase rate of 300-600 degreeC and 600-700 degreeC at the time of dry distillation as shown in Table 4, it dry-distilled similarly to Example 10, and produced the coke of the comparative example 5. . And the crushing strength of the coke of each Example and each comparative example was measured like Example 10. The crushing strength of the coke is shown in Table 4 together with the temperature rising rate and the elapsed time (heating time) from the start of temperature rising.

  FIG. 12 is a graph showing a temperature rise pattern when producing coke of Examples 10 to 15. The production conditions of coke in Examples 10 to 15 differ only in the heating rate of 600 to 700 ° C., and the other production conditions are the same. As shown in Table 4, the production conditions of the coke of Comparative Example 3 differ from Examples 10 to 15 only in the temperature rising rate of 600 to 700 ° C. The production conditions of the coke of Comparative Example 4 are different from those of Examples 10 to 15 in the temperature increase rate of 600 to 700 ° C. and the temperature increase rate of 700 to 900 ° C. The coke production conditions of Comparative Example 5 are different from those of Examples 10 to 15 in the rate of temperature increase of 300 to 600 ° C. and the rate of temperature increase of 600 to 700 ° C.

  FIG. 13 is a graph showing the crushing strength of cokes of Examples 10 to 15 and Comparative Examples 3 to 5. As shown in Table 4, it was confirmed that a coke having a high crushing strength can be produced by setting the heating rate at 600 to 700 ° C. to 5 ° C./min or less.

  According to the present invention, coke having an excellent grate function when used as a heat source for a gasification melting furnace can be produced economically and efficiently. Moreover, according to this invention, coke can be used economically.

DESCRIPTION OF SYMBOLS 10 ... Molding charcoal production part, 11, 17 ... Tank, 12 ... Primary grinder, 13 ... Dryer, 14 ... Secondary grinder, 15 ... Kneading machine, 16 ... Molding machine, 20 ... Dry distillation part, 21 ... Dry distillation furnace 21a ... first tuyere, 21b ... second tuyere, 21c ... gas extraction port, 21d ... cooling gas introduction port, 22 ... tar recovery equipment, 22a ... sensible heat recovery device, 22b ... gas cooler, 23 ... Heat storage furnace, 24 ... heat exchanger, 25 ... ejector, 40 ... gasification melting furnace, 40a ... drying / pre-tropical, 40b ... pyrolysis zone, 40c ... combustion / melting zone, 41, 66 ... coke, 42 ... shaft part 43 ... Pyrolysis residue, 44 ... Morning glory, 45 ... Upper tuyere, 46 ... Furnace bottom, 47 ... Lower tuyere, 49 ... Outlet, 48 ... Waste, 50 ... Charger, 52 ... Exhaust pipe , 60 ... crushing strength measuring device, 62 ... hydraulic jack, 64 ... movable plate, 6 ... fixing plate, 100 ... continuous molding coke production facility, 200 ... gasification melting equipment.

Claims (6)

A method for producing coke by a continuous molding coke production process,
A molding process for obtaining molded coal by pressure molding a raw material containing coal and a binder,
A carbonization step of heating the carbonized coal using a vertical shaft furnace to dry distillation to obtain a coke for gasification melting furnace having a crushing strength of 2500 N or more,
The manufacturing method of the coke for gasification melting furnaces whose average value of the temperature increase rate between 600-700 degreeC in the said carbonization process exceeds 0, and is 5 degrees C / min or less.   The method for producing coke for a gasification melting furnace according to claim 1, wherein the coal in the molding step is composed of only non-coking coal.   The method for producing coke for a gasification melting furnace according to claim 1 or 2, wherein an average particle diameter of the coal in the dry distillation step is 60 mm or more.   The manufacturing method of the coke for gasification melting furnaces as described in any one of Claims 1-3 whose temperature of the top part of the said vertical shaft furnace is 250-400 degreeC. The vertical shaft furnace has a plurality of tuyere for introducing gases having different temperatures into the furnace,
The manufacturing method of the coke for gasification melting furnaces as described in any one of Claims 1-4 whose introduction temperature of the gas with the highest temperature is 850-950 degreeC among the said gas. Introducing the coke and waste obtained by the production method according to any one of claims 1 to 5 into a gasification melting furnace, and heating and melting the waste using the coke as a heat source; How to use coke.

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