JP2001089767A - Production of molded coke - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a molded coke which has a high porosity and a high strength and can reduce ventilation resistance in a blast furnace, and to provide a method for recycling waste plastics as a thermal cracking gas. SOLUTION: This method for producing molded coke comprises adding waste plastics to a blended coal comprising 10 to 50 wt.% of caking coal and 90 to 50 wt.% of fine non-caking coal, press-molding the mixture, and then carbonizing the molded coal. Therein, the waste plastics are preferably added in an amount of 1 to 5 pts.wt. to 100 pts.wt. of the blended coal. The diameter of the waste plastics is preferably <=1/3 of that of the molded coal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing molded coke used for blast furnace coke, and more particularly to a method for producing molded coke characterized by adding waste plastic to a raw material.

[0002]

2. Description of the Related Art There is known a method for producing molded coke used as blast furnace coke. As described in Japanese Patent Publication No. 60-38437, for example, a method for producing a molded coke for a blast furnace is to agglomerate a raw coal mainly containing a non-finely caking coal into a molded coal, and to form the molded coal. This is a method for producing molded coke by carbonization. The typical method is to add tar, pitch, binder such as petroleum asphalt to blended coal mainly containing non-sintered coal,
In this method, coal is formed by agglomeration by pressurizing to a high pressure to form coal, and the coal is directly heated and carbonized in a vertical shaft furnace using a heating gas as a heat medium. The molded coke produced by this method has a problem that when filled in a blast furnace as coke for a blast furnace, the ventilation resistance in the blast furnace increases.

[0003] In order to reduce the ventilation resistance in the blast furnace when using the formed coke, the grain size and shape of the formed coke are changed by increasing the size and changing the shape of the formed coal, and the Methods for reducing the airflow resistance by increasing the porosity when charged are being studied. For example, Japanese Patent Application Laid-Open No. 6-57258 discloses a method.
It is disclosed in JP-A-6-57259 and JP-A-6-57260.

[0004]

However, only by changing the size and shape of the formed coke, there is a limit to the reduction of the ventilation resistance, and when the strength of the formed coke having the changed shape is weak, it is difficult to use the blast furnace. Since the formed coke is broken in the transportation process, it becomes difficult to use the coke as a raw material for the blast furnace.

[0005] Regarding the treatment of waste plastic discharged in large quantities as plastic industrial waste and plastic general waste, most of the waste has conventionally been landfilled or partially incinerated. Waste plastics are not decomposed by bacteria and bacteria in the soil when landfilled, and when incinerated, generate a large amount of heat and adversely affect incinerators.In the case of waste plastics containing chlorine, the treatment of chlorine in exhaust gas is a problem. It has become. It is anticipated that the landfill disposal site will be in short supply in the future, and environmental problems are increasing, and it is desired to promote recycling of waste plastic. As a recycling method, in addition to reuse as plastic, a method of utilizing heat at the time of combustion or a gas or oil obtained by thermal decomposition as a fuel or a chemical raw material can be considered.

The present invention provides a method for producing molded coke which has a high porosity, a high strength and can reduce the ventilation resistance in a blast furnace, and a method for recycling waste plastic as a pyrolysis gas. The purpose is to do.

[0007]

That is, the gist of the present invention is as follows. (1) Includes caking coal and non-micro caking coal, and has a caking coal mixing ratio of 1
A molded coke characterized in that waste plastic is added to a blended coal of 0 to 50% by weight and mixed, the mixture is press-molded to form a molded coal, and the molded coal is carbonized to produce a molded coke. Manufacturing method. (2) 1 waste plastic per 100 parts by weight of coal blend
The method for producing molded coke according to the above (1), wherein ５5 parts by weight are added and mixed. (3) The method for producing molded coke as described in (1) or (2) above, wherein the particle size of the waste plastic is 1/3 or less of the molded coal.

[0008] The present invention is characterized in that waste plastic is added to blended coal mainly containing non-slightly caking coal when producing molded coke. Waste plastic is thermally decomposed by high temperature heating during the production of molded coke, and most of it is volatilized as a decomposition gas. Therefore, the waste plastic portion mixed in the forming coal as the forming coke raw material becomes a pore during the manufacturing of the forming coke, and the air permeability of the forming coke can be improved. The decomposition gas generated by the thermal decomposition of the waste plastic is a high-calorie gas, which is contained and recovered in the coke oven gas and reused as thermal energy.

[0009]

DETAILED DESCRIPTION OF THE INVENTION In general, coal is classified into a caking coal which has a high caking property but is expensive, and a non-fine caking coal which has a low caking property and is inexpensive. In the production of molded coke, caking coal and non-fine caking coal are blended and used in a predetermined ratio so as to obtain a predetermined coke quality. Whereas so-called coke oven coke produces caking coal as a main blend, molded coke is characterized in that the caking coal blending ratio is reduced and non-fine caking coal can be produced as a main blend.

In the present invention, the blended coal as a raw material includes caking coal and non-fine caking coal. If the ratio of caking coal in the blended charcoal exceeds 50% by weight, excessive swelling occurs when dry-forming the formed coal. Therefore, the upper limit of the ratio of caking coal is set to 50% by weight.
If the ratio of the caking coal is too small, it is impossible to produce a high-strength molded coke.
It is defined as 0% by weight.

[0011] Here, non-fine caking coal generally means JIS M
The highest fluidity index is 10 ddpm in the fluidity test by the Giesler plastometer method specified in 8801.
Or coal whose average reflectance of vitrinite is 0.8 or less.

In the coal blend, S is further added as a binder.
Contains OP, tar, pitch, petroleum asphalt, etc. SOP is soft pitch, and is a residue obtained by distilling tar and removing a light oil fraction in the tar.

The waste plastic to be mixed with the blended coal as the raw material for forming coal of the present invention is preferably added by mixing 1 to 5 parts by weight of the waste plastic with respect to 100 parts by weight of the blended coal. If the added amount of waste plastic is less than 1 part by weight, it is not effective as waste plastic recycling, and if the added amount of waste plastic is 5 parts by weight or less, the strength of the molded coke is sufficiently maintained.

On the other hand, if the particle size of the waste plastic added to the coal blend is too large, cracks are formed in the formed coke and the strength of the formed coke is reduced. preferable. More preferably, the particle size of the waste plastic is 1/5 or less of the coal. Here, the particle size of the waste plastic refers to the average particle size, and the size of the formed coal refers to the smallest value among the different lengths, widths, and thicknesses of the formed coal.

[0015] Waste plastic is mixed with blended coal in which caking coal, non-fine caking coal and a binder are blended in a predetermined blending ratio, and molded under pressure to produce molded coal. A double-roll molding machine or the like can be used for pressure molding. The shape of the formed coal after forming is, for example, a shape as shown in FIG.
As the shape of the formed charcoal, a pillow shape and a shape having a concave shape in the center are preferable. If the weight per piece of the coal is too heavy, the coal may be broken during transportation and carbonization. In order to prevent this cracking, the length and width of the formed coal are preferably in the range of 40 to 80 mm. Further, the thickness of the formed coal is preferably about 30 to 50 mm.

FIG. 1 shows a shaft furnace for carbonizing formed coal to form coke. The formed coal is charged from the formed coal charging apparatus 1 and sequentially descends in the shaft furnace dry distillation chamber 2. The dry distillation chamber 2 has a low-temperature gas blowing tuyere 5 and a high-temperature gas blowing tuyere 6, and a gas for forming coal heating is supplied from a low-temperature gas heater 10 and a high-temperature gas heater 11 to each tuyere. The formed coal sequentially descending in the carbonization chamber 2 reaches the carbonization temperature by the hot gas from each tuyere 5, 6, is carbonized to form molded coke, and is discharged from the molded coke discharge port 3 sequentially.

The high-temperature gas introduced from each tuyere 5 and 6 into the carbonization chamber and the pyrolysis gas generated by the carbonization are discharged from the circulation gas extraction duct 4. The gas is cooled by being subjected to flushing with the circulating water in the circulating gas cooler 9, and after separating light oil and tar, a part of the gas is heated again by the gas heaters 10 and 11 and circulated to the carbonization chamber 2. . The remaining gas is recovered by the coke oven gas recovery facility 16 as coke oven gas. The tar is collected by the tar collecting facility 12. After the water is recovered by the water recovery equipment 13, the caustic soda addition equipment 1
By adding caustic soda by 4, ammonium chloride in the sewage is converted into sodium chloride and ammonia, and the ammonia is then vaporized and removed in the deaeration facility 15.

Most of the waste plastic is thermally decomposed due to the high temperature at the time of coking dry distillation, and becomes high calorie reduction decomposition gas such as hydrogen, methane, ethane and propane. This cracked gas is contained in the circulating gas and discharged from the circulating gas extraction duct 4, and then recovered as coke oven gas. The pyrolysis gas generated by the pyrolysis of waste plastic is
As described above, the gas contained in the coke oven gas is recovered and reused as an energy source. The remaining carbon becomes part of coke and is reused in the blast furnace.

The space occupied by the waste plastic in the formed coal becomes a cavity as a result of the pyrolysis of the waste plastic, and becomes formed coke having a large number of cavities. The presence of these cavities increased the permeability of the formed coke, and made it possible to reduce the ventilation resistance when used in a blast furnace.

When heat-treating waste plastics containing chlorine, it is necessary to heat-treat at a sufficiently high temperature in the environment. When carbonized coal is distilled in a vertical shaft furnace as in the present invention, the temperature during carbonization reaches 1100 ° C. at the maximum. 250 for polyvinyl chloride and polyvinylidene chloride
Thermal decomposition starts at about 400 ° C., gasifies at about 400 ° C., and decomposes almost completely at 1100 ° C. Therefore, as long as the chlorine-containing waste plastic is mixed with the formed coal in the shaft furnace and pyrolyzed, the pyrolysis or carbonization temperature and the carbonization pattern may be the same as those of conventional coal carbonization.

[0021] The chlorine-based gas derived from the waste plastic generated when the chlorine-containing waste plastic is heated reacts with the excess ammonia generated during the carbonization of coal to form ammonium chloride. The ammonium chloride is supplied to the circulating gas cooler 9
Is taken into the circulating water for cooling the circulating gas. Ammonium chloride is decomposed into sodium chloride and ammonia by adding a strong base, for example, sodium hydroxide (caustic soda), to the aqueous solution in which ammonium chloride has accumulated in a large amount. In FIG. 1, the caustic soda addition equipment 14
In step 2, caustic soda is added to the cold water.

Conventionally, a coke oven is provided with a deaeration facility 15 for treating low-temperature water taken out of the system. In the dewaxing facility 15, after free ammonia is vaporized and removed by steam stripping, activated sludge treatment is performed and discharged. As described above, ammonium chloride is converted into sodium chloride and ammonia by sodium hydroxide before entering the deaeration facility, as described above, so all nitrogen components contained in the water are contained in the form of ammonia. I have. Therefore, as a result of ammonia being vaporized and removed in the deaeration facility 15, the nitrogen component in the deionized water is removed. Since only harmless sodium chloride remains in the dewatered water leaving the deaeration facility, there is no risk of increasing the nitrogen content in seawater even if the water is discharged as it is.

[0023]

EXAMPLE Coking coal shown in Table 1 was used as blended coal, waste plastics having properties shown in Table 2 were blended, and 3% of SOP was added as a binder and kneaded, and pressurized at a linear pressure of 2 t / cm. It was molded to produce molded coal. The shape of the coal is as shown in FIG. Waste plastic addition rate of each example,
Average particle size of added waste plastics, length of forming coal,
The width and thickness are as shown in Table 3. Fig. 1
1100 ° C. (No. 5 only 1150 ° C.)
C) to form a molded coke. No. 3 in Table 3. Nos. 1 to 5 are examples of the present invention. 6 to 10 are comparative examples.

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

[Table 3]

The strength of the formed coke is determined by the drum strength (DI
¹⁵⁰ ₁₅ ). Coke drum strength (D
I ¹⁵⁰ ₁₅ ) is, as described in JIS K 2151, charged with 10 kg of coke into a drum tester (both in diameter and length, 1500 mm, four blades), rotated 150 times, and then passed through a 15 mm sieve. It is the value expressed as a percentage of the mass that was sieved and remained on the sieve. In this embodiment, DI
^{When 150} ₁₅ was 82% or more, it was determined that the coke had good strength as blast furnace coke.

The air permeability when the molded coke was used in a blast furnace was evaluated by the porosity of the molded coke. As a method of measuring the airflow resistance, a method was used in which a molded coke was filled to a height of 500 mm into an airflow resistance measuring device having a radius of 600 mm, air was introduced from below, and the differential pressure of the packed layer was measured. In this example, if the porosity was 40% or more, it was determined that the molded coke for blast furnace had good air permeability.

No. 1 of the present invention example. Nos. 1 to 5 are in a suitable range for both the addition ratio of the waste plastic and the particle size, the drum strength is a sufficiently high value, the strength as a coke for blast furnace is high, and the porosity is also a high value. Since the ventilation resistance in each case can be reduced, a high-quality molded coke can be produced in each case.

No. of Comparative Example No. 6 shows the case where no waste plastic is added. Although the coke strength is high, the porosity is low, and the ventilation resistance in the blast furnace when used as blast furnace coke cannot be reduced.

No. of Comparative Example In Nos. 7 to 10, although the waste plastic was added, the permeability of the formed coke was good, but the average particle size of the added waste plastic exceeded 1/3 of the thickness of the formed charcoal. The drum strength of the formed coke was low, and sufficient strength was not obtained as blast furnace coke.

[0032]

According to the present invention, by adding waste plastic to the raw coal of molded coke used for blast furnaces, it is possible to produce high-quality molded coke having high porosity and high strength. As a result, when the molded coke is used in the blast furnace, the ventilation resistance in the blast furnace can be reduced, and the waste plastic can be effectively recycled.

[Brief description of the drawings]

FIG. 1 is a diagram showing a shaft furnace for producing molded coke used in the present invention.

FIG. 2 is a view showing a shape of a formed coal.

[Description of Signs] 1 Molded charcoal charging device 2 Shaft furnace dry distillation chamber 3 Molded coke outlet 4 Circulating gas extraction duct 5 Low temperature gas injection tuyere 6 High temperature gas injection tuyere 7 Heated gas extraction duct 8 Cooling gas injection tuyere 9 Circulating gas cooler 10 Low temperature gas heater 11 High temperature gas heater 12 Tar recovery equipment 13 Water recovery equipment 14 Caustic soda addition equipment 15 Deaeration equipment 16 Coke oven gas recovery equipment

Claims (3)

[Claims] 1. A waste plastic is added to a coal blend containing caking coal and non-fine caking coal and having a blending ratio of caking coal of 10 to 50% by weight and mixed, and the mixture is subjected to pressure molding. A method for producing molded coke, comprising forming molded coal and carbonizing the molded coal to produce molded coke. 2. The method for producing molded coke according to claim 1, wherein 1 to 5 parts by weight of waste plastic is added to 100 parts by weight of the blended coal and mixed. 3. The particle size of the waste plastic is reduced to 1/3 of that of the formed coal.
The method for producing molded coke according to claim 1 or 2, wherein: