JP2014181249A - Coal combustion auxiliary composition, coal combustion auxiliary agent using the composition and coal combustion method using the coal combustion auxiliary agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coal combustion auxiliary composition which removes sulfur content efficiently from coal for combustion when mixed with the coal for combustion and burnt, reduces unburnt ingredients contained in the combustion ash, or fly ash, by improving the ignitability and combustibility of the coal for combustion and thereby secures efficient combustion of the coal for combustion.SOLUTION: A powder type coal combustion auxiliary agent composition to be added to coal for combustion contains calcium carbonate and biomass in a ratio of 10-25 pts.mass of biomass to 100 pts.mass of calcium carbonate and contains further coal for combustion promotion. The mass ratio of the combined amount of calcium carbonate and biomass to the amount of the coal for combustion promotion is (90:10) to (25:75).

Description

  The present invention relates to a coal combustion aid composition containing calcium carbonate, biomass, and the like, a coal combustion aid formed using this composition, and a method for burning combustion coal using this coal combustion aid. It is.

  Conventionally, an aqueous solution or suspension of slaked lime is attached to a biomass material made of biomass powder or pulverized biomass, the biomass material to which this liquid is attached is heated to 80 to 100 ° C., and the heated biomass material is 80 to A method for producing a biomass-based molded fuel that is heated and molded into a briquette or plate shape by applying a pressure of 100 to 500 MPa with a double roll press at a temperature of 100 ° C. is disclosed (for example, see Patent Document 1). .

  In the manufacturing method of the biomass type | mold molded fuel comprised in this way, plasticity is provided to biomass raw material by attaching the aqueous solution of slaked lime etc. to the biomass raw material which consists of biomass powder etc., and the biomass raw material which this liquid adhered is 80 By heating to ~ 100 ° C, plasticity is further imparted to the biomass material, and the heated biomass material is subjected to a pressure of 100 to 500 MHz by a double roll press at a temperature of 80 to 100 ° C to form a briquette or the like. By heating and molding, the fuel is molded with a high compressive force while applying a strong shearing force to the fibrous biomass raw material in the presence of steam. As a result, fibrous biomass raw materials are strongly entangled with each other, and a molded fuel having a relatively high density can be obtained. When coal and biomass are co-fired at the same time, the combustion efficiency is increased, or the nitrogen content contained in the woody biomass is less than the nitrogen content contained in the coal, so that the concentration of NOx in the exhaust gas can be reduced.

JP 2009-51985 (Claim 1, paragraphs [0010] and [0021], FIG. 1)

  However, in the method for producing a biomass-based molded fuel disclosed in Patent Document 1 above, slaked lime as a combustion aid is used for mere desulfurization purposes, and biomass as a combustion aid is the use of biomass with a low nitrogen content. Is used for the purpose of denitrification by that amount, and in mixed combustion such as pulverized coal combustion and circulating fluidized bed, improvement of coal combustibility, suppression of generation of air pollutants, reforming of combustion ash (fly ash) There is a problem that multi-faceted effects such as cannot be obtained.

  The first object of the present invention is to efficiently remove sulfur from combustion coal when it is mixed with combustion coal and combusted, and combustion ash (fly ash) is improved by improving the ignitability and combustibility of combustion coal. ) Coal combustion aid composition, coal combustion aid using the composition, and coal using the coal combustion aid, which can reduce unburned components contained therein and thereby efficiently burn coal for combustion It is in providing the combustion method of this. The second object of the present invention is to provide a coal combustion aid composition that can suppress the NOx generation amount derived from the volatile matter during combustion of pulverized coal to less than the emission standard value and coal combustion assistance using the composition. It is providing the coal combustion method using the agent and the coal combustion auxiliary agent. A third object of the present invention is a coal combustion auxiliary composition capable of suppressing release of harmful components into the atmosphere by immobilizing a trace amount of harmful metal components in combustion coal to combustion ash and its An object of the present invention is to provide a coal combustion auxiliary using the composition and a method for burning coal using the coal combustion auxiliary. The fourth object of the present invention is to obtain a combustion ash having a good particle size structure, which is self-hardening as well as pozzolanic reactivity, and does not contain porous coarse particles that become a strength defect of a cured product. An object of the present invention is to provide a coal combustion aid composition, a coal combustion aid using the composition, and a method for burning coal using the coal combustion aid.

  A first aspect of the present invention is a powdery coal combustion aid composition used for adding to combustion coal and containing calcium carbonate and biomass, wherein the biomass is added to 100 parts by mass of calcium carbonate. It contains 10 to 25 parts by mass.

  2nd viewpoint of this invention is invention based on 1st viewpoint, Comprising: The coal for combustion promotion is further included, The total amount of calcium carbonate and biomass, and the quantity of coal for combustion promotion are mass ratio (90: 10) to (25:75).

  A third aspect of the present invention is a coal combustion aid formed by molding the powdery coal combustion aid composition described in the first or second aspect into a flat plate shape, a briquette shape, or a granular shape.

  According to a fourth aspect of the present invention, the powdery coal combustion auxiliary composition described in the first or second aspect is 50 to 400 MPa in pressure, 15 mm or less in thickness, and has a length, width, or diameter. It is a coal combustion aid formed into a flat plate shape of 100 mm or less, or a briquette shape with a volume of 30 ml or less, or by pulverizing these products into granules with a particle size of 20 mm or less. .

  A fifth aspect of the present invention is a step of mixing 10 to 5% by mass of the coal combustion aid according to the third or fourth aspect with respect to 90 to 95% by mass of fuel coal having a particle size of 80 mm or less, And a step of supplying the mixture to a fluidized bed combustion furnace and burning the mixture.

  The 6th viewpoint of this invention mixes 10-5 mass% of coal combustion adjuvants as described in the 3rd or 4th viewpoint with respect to 90-95 mass% of coal for combustion with a particle diameter of 80 mm or less, and particle diameter is 75 micrometers. It is a coal combustion method including a step of pulverizing so as to include 70 to 80% by mass of the following, and a step of supplying the pulverized mixture to a pulverized coal combustion furnace and burning it.

  In the coal combustion auxiliary composition of the first aspect of the present invention, 10 to 25 parts by mass of biomass is contained with respect to 100 parts by mass of calcium carbonate. Therefore, when the coal combustion auxiliary is molded using this composition. Biomass in the composition acts as a binder and gives properties and strength that can withstand normal storage and handling. In addition, when the coal combustion aid molded using the above composition is mixed with combustion coal and combusted, calcium oxide derived from calcium carbonate in the coal combustion aid is sulfur content in the combustion coal, etc. It reacts with harmful components to immobilize these harmful components, and the release of harmful components in combustion coal into the atmosphere can be suppressed. In addition to the ignitability of combustion coal by biomass, it can improve the flammability due to the catalytic action of calcium oxide, thereby reducing the unburned components contained in the combustion ash (fly ash), so the combustion coal can be efficiently used Can burn.

  In the coal combustion aid composition according to the second aspect of the present invention, in the fluidized bed combustion at 850 to 860 ° C., the coal combustion aid is finely divided when mixed with combustion coal and burned. In addition to further improving the ignitability and combustibility of coal for combustion, the calcium carbonate derived from calcium carbonate is dispersed, so that this calcium carbonate reacts with harmful components such as sulfur in the combustion coal, and this harmful component is reduced. Immobilization can suppress the release of harmful components in combustion coal into the atmosphere. Similarly, in pulverized coal combustion at 1400 to 1500 ° C., the coal-composite pulverized combustion aid containing biomass, calcium carbonate, and combustion-promoting coal is divided and dispersed uniformly, This contributes to the dispersion of charcoal (combustion coal) and greatly improves its combustibility. In addition, the particle size composition of combustion ash (fly ash) generated by combustion reduces the fine particles (submicron particles) and increases the coarseness. The particles are transferred to the fine particles side by the coal particle splitting, and the dust collection effect and the structure of good particle size for utilization of civil engineering materials are obtained.

  In the coal combustion aids according to the third and fourth aspects of the present invention, the biomass in the coal combustion aid acts as a binder and gives properties and strength that can withstand normal storage and handling. In addition, when the coal combustion aid is mixed with combustion coal and burned, calcium oxide derived from calcium carbonate in the coal combustion aid reacts with harmful components such as sulfur in the combustion coal to cause this harmful effect. By immobilizing components, it is possible to suppress the release of harmful components in combustion coal into the atmosphere. In addition, the use of coal combustion aids containing calcium carbonate and biomass can improve the ignitability of combustion coal by biomass and the combustibility due to the catalytic action of calcium oxide, thereby unburned components contained in the combustion ash. Therefore, combustion coal can be burned efficiently. By using a coal combustion aid containing calcium carbonate, biomass and combustion promoting coal, the ignitability and combustibility of the combustion coal can be further improved in both fluidized bed combustion and pulverized coal combustion. Since unburned components contained therein can be further reduced, combustion coal can be burned more efficiently.

  In the coal combustion method according to the fifth aspect of the present invention, in the fluidized bed combustion, when a coal combustion aid containing calcium carbonate, biomass, and combustion promoting coal is used, compared to the case of burning only the combustion coal. As the amount of combustion per unit time increases, the granulated coal combustion aid is instantly split and uniformly dispersed in the combustion coal, greatly increasing the ignitability and combustibility of the combustion coal. It can be improved. As a result, unburned components in the combustion ash can be greatly reduced, so that the amount of combustion coal used can be reduced. Although the amount of NOx derived from the volatile matter in the combustion coal slightly increases due to the improvement of the combustibility, the amount of NOx generated can be suppressed below the emission standard value, and the calcium carbonate in the coal combustion aid can be reduced. The derived calcium oxide absorbs the sulfur content in the combustion coal and reacts with this sulfur content, so that the sulfur content in the combustion coal is hardly released into the atmosphere. In addition, by fixing harmful components in combustion coal to combustion ash, it is possible to suppress the release of harmful components to the atmosphere. Furthermore, since the unburned components in the combustion ash are reduced, when the combustion ash is used as a cement admixture, the hydration and hardening characteristics of the cement can be improved and the blending of cement and the like can be reduced. It can be used effectively as a material.

  In the method for burning coal according to the sixth aspect of the present invention, when a coal combustion aid containing calcium carbonate, biomass, and coal for combustion promotion is used, the combustion promoting action of this three-component composite coal combustion aid, In addition to reducing the unburned components in the combustion ash, it is possible to suppress the coarsening and porosity of the combustion ash (fly ash) related to the unburned carbon from the combustion coal, especially in pulverized coal combustion. Strength can be improved, that is, self-hardening can be imparted to the combustion ash particles. By preventing a decrease in the strength of the combustion ash particles, it can be effectively used as a civil engineering material. In addition, among toxic components in combustion coal, volatile toxic components are fixed by contacting and reacting with calcium-based substances, which are pyrolysis products of calcium carbonate, and non-volatile toxic components are burnt ash by high temperature melting. Therefore, the property of combustion ash can be improved by immobilization and non-elution in the combustion furnace. As a result, the combustion ash can be effectively used as a new civil engineering material such as a water-permeable ground material. Further, the chemical composition of the combustion ash is improved by reducing the unburned components in the combustion ash and increasing the calcium component from the combustion aid, so that the polazone reactivity can be improved. Due to the improvement of the polyazone reactivity and the provision of the above-mentioned self-hardening property, a sufficient cement strength can be expressed with poor blending of about 5% by mass of cement. Here, the pozzolanic reaction is the hydroxylation produced by mixing the combustion ash (fly ash) with Portland cement and adding water to the silicon dioxide contained in the combustion ash (fly ash). A reaction that reacts with calcium to form a dense and durable hydrated calcium silicate. Furthermore, in the pulverized coal combustion, the coal combustion aid is instantaneously divided and the coal combustion aid is uniformly dispersed, thereby promoting the division and combustion of the nearby cloudy pulverized coal for combustion (combustion coal), The ignitability and combustibility of pulverized coal for combustion (combustion coal) can be greatly improved. In addition, the particle size composition of the combustion ash particles is improved, that is, the particle size of the combustion ash particles is substantially uniform, so that the combustion ash can be efficiently and electrically collected by reducing the fine particles (submicron particles), and the combustion ash The porous coarse particles in the inside are reduced, and for example, by collecting fine particles having a particle size of 40 μm or less by classification, the yield can be greatly improved in using the combustion ash. As a result, the combustion ash can be effectively used as a civil engineering material such as cement admixture or concrete admixture.

The flowchart which burns coal for combustion using this coal combustion auxiliary agent, after shape | molding coal combustion auxiliary agent using the coal combustion auxiliary agent composition which contains calcium carbonate and biomass of 1st Embodiment of this invention, and was manufactured with the wet method. FIG. It is a flowchart figure which burns coal for combustion using this coal combustion assistant, after shape | molding a coal combustion assistant using the coal combustion assistant composition which contains calcium carbonate and biomass and was manufactured with the dry process. The coal combustion aid is molded using the coal combustion aid composition containing the calcium carbonate, biomass and combustion promoting coal of the second embodiment of the present invention and manufactured by a wet method, and then the coal combustion aid is used for combustion. It is a flowchart figure which burns coal. In the flowchart figure which burns coal for combustion using this coal combustion auxiliary agent after shape | molding coal combustion auxiliary agent using the coal combustion auxiliary agent composition which contains calcium carbonate, biomass, and combustion promotion coal, and was manufactured by the dry method is there. It is a figure which shows the change of the furnace temperature with respect to the height of a fluidized-bed combustion furnace when the coal combustion adjuvant of Examples 6-8 and the comparative example 2 is mixed with combustion coal, and combusted. It is a figure which shows the change of NOx generation amount with respect to an unburned rate when the coal combustion auxiliary | assistance of Example 9 and 10 and the comparative example 3 is mixed with combustion coal, and it burns. It is a principal part perspective view which shows the state which is performing the destructive strength test of tablets, such as combustion ash of Examples 11-16 and Comparative Examples 4-6. It is a figure which shows the breaking strength of tablets, such as combustion ash of Examples 11-16 and Comparative Examples 4-6. It is a figure which shows the particle size distribution (frequency and accumulation rate) of the combustion ash (fly ash) which generate | occur | produced when the coal fuel adjuvant of the comparative example 3 was added to the coal for combustion, and it grind | pulverized and combusted. It is a figure which shows the particle size distribution (frequency and accumulation rate) of the combustion ash which generate | occur | produced when the coal fuel adjuvant of Example 9 was added to the coal for combustion, and it grind | pulverized and combusted.

  Next, an embodiment for carrying out the present invention will be described with reference to the drawings.

<First Embodiment>
The powdery coal combustion auxiliary composition of the present invention contains calcium carbonate and biomass. This coal combustion auxiliary composition contains 10 to 25 parts by mass of biomass on a dry matter basis with respect to 100 parts by mass of calcium carbonate. Here, the reason why the biomass content relative to 100 parts by mass of calcium carbonate is limited to the range of 10 to 25 parts by mass is based on the following reason. If the biomass is less than 10% by mass, the amount of biomass is too small and the biomass does not act as a binder, and properties and strength that can withstand normal storage, handling, etc. of coal combustion aids molded using this composition This is because the ignitability and combustibility as a coal combustion aid cannot be improved. On the other hand, if the biomass exceeds 25% by mass, the properties and strength of the coal combustion aid formed from the composition are hardly improved in spite of an increase in the content of biomass, and the ignitability as a coal combustion aid. This is because the flammability is hardly improved. Further, the dry matter base refers to a state in which the moisture content of the biomass is about 0% by holding the biomass at a temperature of 105 ° C. for 1 hour and drying it.

  Examples of the calcium carbonate include limestone and combustible calcium carbonate. As the limestone, heavy calcium carbonate obtained by pulverizing limestone to a particle size of 150 μm or less, preferably 75 μm or less, or synthetic calcium carbonate obtained by carbonated quick lime is used. In addition, combustible calcium carbonate is a sugar product (lime cake) discharged in a sugar manufacturing process at a sugar factory, or a pulverized product obtained by drying shells such as scallops and oysters to a particle size of 150 μm or less, preferably 10 μm or less. Etc. are used. The sugar effluent (lime cake) contains organic substances in addition to calcium carbonate, and pulverized products such as scallops and oysters contain organic combustible components in addition to calcium carbonate. The organic matter and the organic combustible component function as the biomass of the present invention or a part thereof. On the other hand, examples of the biomass include waste paper, wood waste, agricultural waste, agricultural processing by-products, agricultural processing emissions, and the like. Waste paper is used after being crushed in newspaper, magazines, cardboard and the like and then dried. Further, the wood waste material is obtained by drying and pulverizing sawdust, sawmill processing waste material (end material), old building material (wood house waste material) or the like. Agricultural waste, by-products of agricultural processing, and agricultural processing discharges are obtained by drying and pulverizing rice straw, rice husk, beet pulp, bagasse and the like.

  The powdery coal combustion aid composition is formed into a flat plate shape, briquette shape or granule shape to produce a coal combustion aid. Specifically, by molding the powdery coal combustion aid composition at a pressure of 50 to 400 MPa, preferably 200 to 300 MPa, the thickness is 15 mm or less, preferably 10 mm or less, and the length and width or diameter. Are each made of a plate-like (square plate or disk) coal combustion aid having a size of 100 mm or less, preferably about 50 mm, or a briquette coal combustion aid having a volume of 30 ml or less, preferably 10 to 20 ml. Is done. Further, the above-mentioned flat or briquette coal combustion aid is pulverized to a particle size of 20 mm or less, preferably 10 to 1 mm to produce a granular coal combustion aid.

  Here, the molding pressure of the powdery coal combustion aid composition is limited to the range of 50 to 400 MP because a hard molded product cannot be obtained if it is less than 50 MPa, and the molded product is harder than necessary if it exceeds 400 MPa. Because it becomes. Moreover, the reason why the thickness of the flat coal combustion aid is limited to 15 mm or less is that when it exceeds 15 mm, a hard molded product cannot be obtained. The reason why the length, width, or diameter of the plate-like coal combustion aid is limited to 100 mm or less is that if it exceeds 100 mm, the handleability of the molded product is lowered. Further, the reason why the volume of the briquette coal combustion aid is limited to 30 ml or less is that when it exceeds 30 ml, the handleability of the molded product is lowered. The reason why the particle size of the granular coal combustion aid is limited to 20 mm or less is that if it exceeds 20 mm, a hard molded product cannot be obtained.

  In the coal combustion aid configured as described above, the biomass in the coal combustion aid acts as a binder and gives properties and strength that can withstand normal storage and handling.

  Next, a specific method for producing a flat or briquette coal combustion aid using the powdered coal combustion aid composition will be described with reference to FIGS. There are a wet method and a dry method as a method for producing a coal combustion aid.

[1-1] Method for producing coal combustion auxiliary by wet method (FIG. 1)
First, calcium carbonate such as limestone and biomass such as waste paper are weighed so as to have a predetermined ratio, and these are crushed and pulverized in water so that the particle size is 150 μm or less, preferably 75 μm or less, Mix uniformly to prepare a slurry. Next, the slurry is squeezed and dehydrated so that the water content becomes 30 to 40%, and then the dehydrated product is dried to a moisture content of 5 to 10% and subjected to high pressure molding, or the dried product is 70 to 80 ° C. In the state heated to high pressure, a flat or briquette coal combustion aid is produced. The high-pressure molding is a roll-type high-pressure molding by binderless without adding any binder other than biomass because biomass acts as a binder under a shearing force mainly composed of compressive force. Here, the reason why the particle size of the mixture in the slurry was pulverized and pulverized so as to be 150 μm or less is that when the particle diameter exceeds 150 μm, the strength of the high-pressure molded product and the reactivity due to calcium carbonate decrease. In addition, when using the sugar production effluent (lime cake), the water content of the sugar production effluent is about 30%, and the biomass contained in the sugar production effluent is 10 to 13% by mass on a dry matter basis. As a composite material containing both biomasses, the above wet process is performed to produce a flat or briquette coal combustion aid. The granular coal combustion aid is produced by crushing the flat or briquette coal combustion aid.

[1-2] Method for producing coal combustion aid by dry method (Figure 2)
First, calcium carbonate such as limestone is pulverized to a particle size of 150 μm or less, preferably 74 μm or less. Next, plant fiber biomass such as wood waste and agricultural waste whose moisture is about 15% by natural drying is pulverized to a particle size of 2.0 mm or less, preferably 1.0 mm or less. Here, examples of the wood waste include sawdust, sawmill processing waste (endwood), old building materials (wood house waste), and agricultural wastes include rice straw and rice husks. Furthermore, after mixing the said grind | pulverized calcium carbonate and biomass, this mixture is high-pressure-molded in the state heated to 70-80 degreeC at room temperature, or a flat or briquette coal combustion auxiliary agent is manufactured. The high-pressure molding is a roll-type high-pressure molding by binderless without adding any binder other than biomass because biomass acts as a binder under a shearing force mainly composed of compressive force. Here, when the particle size of the calcium carbonate is reduced to 150 μm or less, if the particle size exceeds 150 μm, the surface area of the calcium oxide derived from the calcium carbonate is reduced, so that the adsorptivity of volatile harmful components in the coal for combustion is increased. This is because the reactivity with volatile harmful components decreases. The granular coal combustion aid is produced by crushing the flat or briquette coal combustion aid.

  A method for burning combustion coal using the coal combustion aid produced by the methods [1-1] and [1-2] will be described with reference to FIGS. 1 and 2. Combustion methods of combustion coal include a fluidized bed combustion method and a pulverized coal combustion method.

[1-3] Coal Combustion Method Using Fluidized Bed Combustion Method First, 90 to 95% by mass of combustion coal having a particle size of 80 mm or less, preferably 0.5 to 10.0 mm, and the above [1-1] and [1] -2] is mixed with 10-5% by mass of coal combustion aid produced by the method of [-2]. Next, this mixture is supplied to a fluidized bed combustion furnace and burned. Here, the mixing ratio of the coal combustion aid is limited to the range of 10 to 5% by mass, and if the ratio exceeds 10% by mass, the effect of combustion (mixed combustion) is small as the ratio is increased. This is because there is a problem in terms of economy that the burden on the cost is increased, and if it is less than 5% by mass, the characteristic that the coal combustion auxiliary agent exhibits the multifaceted effect cannot be utilized. Combustion coal includes steam coal (fuel ratio (fixed carbon / volatility by industrial analysis) used in large or medium-sized or small boiler combustion furnaces used in power generation, steam generation, etc. Min): 0.8 to 2.5). For example, Newlands coal (NL coal) produced in Australia, Kushiro Colemine coal (KCM coal) produced in Kushiro, Hokkaido, etc. are mentioned.

[1-4] Coal Combustion Method by Pulverized Coal Combustion Method First, 90 to 95% by mass of combustion coal having a particle size of 80 mm or less, preferably 30 mm or less, and the methods of [1-1] and [1-2] above. Is mixed with 10 to 5% by mass of the coal combustion aid produced in step 1, and then the mixture is pulverized to the particle size of coal used in ordinary pulverized coal combustion, that is, the mixture has a particle size of 75 μm. It grind | pulverizes so that the following may be included including 70-80 mass% and a particle size of 250 micrometers or less. Next, this pulverized mixture is supplied to a pulverized coal combustion furnace and burned.

  When coal is burned by the above methods [1-3] and [1-4], calcium carbonate in the coal combustion aid reacts with harmful components such as sulfur in the combustion coal to immobilize this harmful component. Thus, it is possible to suppress the release of harmful components in combustion coal into the atmosphere. Moreover, since the ignitability and combustibility of combustion coal can be improved by biomass, unburned components contained in the combustion ash (fly ash) can be reduced. As a result, the combustion coal can be burned efficiently.

<Second Embodiment>
3 and 4 show a second embodiment of the present invention. In this embodiment, the coal combustion aid composition further includes combustion promoting coal in addition to calcium carbonate and biomass. Here, as the combustion promoting coal, as in the combustion coal of the first embodiment, it is used overseas or domestically used in large, medium or small boiler combustion furnaces for power generation, steam generation, etc. General coal produced (fuel ratio by industrial analysis (fixed carbon / volatile content): 0.8 to 2.5). For example, Newlands coal (NL coal) produced in Australia, Kushiro Colemine coal (KCM coal) produced in Kushiro, Hokkaido, etc. are mentioned. However, the combustion promoting coal may use the same coal type as the combustion coal, or may use a different coal type. Further, the total amount of calcium carbonate and biomass and the amount of coal for promoting combustion are mass ratios of (90:10) to (25:75), preferably (60:40) to (40:60). Contains. Here, the reason why the mixing ratio of the total amount of calcium carbonate and biomass and the amount of coal for combustion promotion is limited to the range of (90:10) to (25:75) by mass ratio is as follows. The coal combustion aid of the present invention exhibits a multifaceted effect by making calcium carbonate, biomass, and combustion promoting coal into a composite system mixture at an appropriate composition ratio. Therefore, the amount of combustion promoting coal is 10 If it is less than mass%, the combined effect on the combustion characteristics of coal blended for combustion promotion is greatly impaired, and when the combustion promotion coal is mixed with the combustion coal and pulverized, it is selectively pulverized. However, there is a great difficulty that the combustion promoting coal cannot be pulverized so as to be uniformly dispersed in the combustion coal. Also, if the amount of coal for promoting combustion exceeds 75% by mass, a sufficiently strong coal combustion aid molded product cannot be obtained due to the reduction of fine particulate calcium carbonate and biomass acting as a binder. There is a problem. In addition, the said mixing rate is the value measured on the dry matter base whose moisture content of biomass is 0%.

  The powdery coal combustion aid composition is formed into a flat plate shape, briquette shape or granule shape to produce a coal combustion aid. Specifically, by molding the powdery coal combustion aid composition at a pressure of 50 to 400 MPa, preferably 200 to 300 MPa, the thickness is 15 mm or less, preferably 10 mm or less, and the length and width or diameter. Are each made of a plate-like (square plate or disk) coal combustion aid having a size of 100 mm or less, preferably about 50 mm, or a briquette coal combustion aid having a volume of 30 ml or less, preferably 10 to 20 ml. Is done. Further, the above-mentioned flat or briquette coal combustion aid is pulverized to a particle size of 20 mm or less, preferably 10 to 1 mm to produce a granular coal combustion aid. The reason why the molding pressure of the powdery coal combustion aid composition is limited to the range of 50 to 400 MP, the reason that the thickness of the flat coal combustion aid composition is limited to 15 mm or less, and the single plate-like coal combustion Reasons for limiting the vertical and horizontal or diameter of the auxiliary agent to 100 mm or less, the reason for limiting the volume of briquette coal combustion auxiliary to 30 milliliters or less, and the particle size of granular coal combustion auxiliary to 20 mm or less The reason is the same as the reason described in the first embodiment.

  In the coal combustion aid configured as described above, the biomass in the coal combustion aid acts as a binder and gives properties and strength that can withstand normal storage and handling.

  Next, a specific method for producing a plate-like or briquette-like coal combustion aid using the powdery coal combustion aid composition will be described with reference to FIGS. There are a wet method and a dry method as a method for producing a coal combustion aid.

[2-1] Method for producing coal combustion auxiliary by wet method (Fig. 3)
First, calcium carbonate such as limestone and biomass such as waste paper are weighed so as to have a predetermined ratio, and these are crushed and pulverized in water so that the particle size is 150 μm or less, preferably 75 μm or less, Mix uniformly to prepare a slurry. Next, this slurry is squeezed and dehydrated so that the water content becomes 30 to 40%. Furthermore, after drying so that the moisture content of the dehydrated product is 5 to 10%, the pulverized product is pulverized so that the particle size becomes 3.0 to 5.0 mm or less so that the particle size becomes 2.0 mm. The combustion-promoting coal pulverized into the above-mentioned ratio is mixed, and the mixture is subjected to high-pressure molding as it is, or high-pressure molding in a state of being heated to 70 to 80 ° C. to obtain a flat or briquette coal combustion aid. Manufacturing. The high-pressure molding is a roll-type high-pressure molding by binderless without adding any binder other than biomass because biomass acts as a binder under a shearing force mainly composed of compressive force. In addition, when using the sugar production effluent (lime cake), the water content of the sugar production effluent is about 30%, and the biomass contained in the sugar production effluent is 10 to 13% by mass on a dry matter basis. A composite raw material containing both biomass is used, and combustion-promoting coal is added to the dried product and mixed to produce a flat or briquette coal combustion aid. The granular coal combustion aid is produced by crushing the flat or briquette coal combustion aid.

[2-2] Coal combustion aid manufacturing method by dry method (Figure 4)
First, calcium carbonate such as limestone is pulverized so that the particle size is 150 μm or less, preferably 75 μm or less. Next, plant fiber biomass such as wood waste and agricultural waste whose moisture is about 15% by natural drying is pulverized to a particle size of 2.0 mm or less, preferably 1.0 mm or less. Here, examples of the wood waste include sawdust, sawmill processing waste (endwood), old building materials (wood house waste), and agricultural wastes include rice straw and rice husks. Furthermore, after mixing the combustion-promoting coal pulverized so that the particle size is 1.0 mm or less into the mixture obtained by mixing the pulverized calcium carbonate and biomass, the mixture is heated to 70 to 80 ° C. In the state heated to high pressure, a flat or briquette coal combustion aid is produced. The high-pressure molding is a roll-type high-pressure molding by binderless without adding any binder other than biomass because biomass acts as a binder under a shearing force mainly composed of compressive force. The granular coal combustion aid is produced by crushing the flat or briquette coal combustion aid.

  A method for burning combustion coal using the coal combustion aid produced by the methods [2-1] and [2-2] will be described with reference to FIGS. 3 and 4. Combustion methods of combustion coal include a fluidized bed combustion method and a pulverized coal combustion method.

[2-3] Coal Combustion Method by Fluidized Bed Combustion Method First, coal for combustion having a particle size of 80 mm or less, preferably 0.5 to 10 mm, 90 to 95% by mass, the above [2-1] and [2- 2) 10 to 5% by mass of coal combustion aid produced by the method of [2]. Next, this mixture is supplied to a fluidized bed combustion furnace and burned. Here, the reason why the mixing ratio of the coal combustion aid is limited to the range of 10 to 5% by mass is the same as the reason for the first embodiment. The combustion coal is the same as the combustion coal of the first embodiment.

  When coal is burned by the method described in [2-3] above, the amount of combustion per unit time is increased and the coal combustion aid is instantaneously split compared to the case of burning only coal for combustion. By uniformly dispersing the coal combustion aid, the ignitability and combustibility of the combustion coal can be greatly improved. As a result, unburned components in the combustion ash can be greatly reduced, so that the amount of combustion coal used can be reduced. Although the amount of NOx derived from the volatile matter in the combustion coal slightly increases due to the improvement of the combustibility, the amount of NOx generated can be suppressed below the emission standard value, and the calcium carbonate in the coal combustion aid can be reduced. The sulfur content in the combustion coal is hardly released into the atmosphere due to the reaction between the calcium oxide derived from the sulfur content in the combustion coal. In addition, by fixing harmful components in combustion coal to combustion ash, it is possible to suppress the release of harmful components to the atmosphere. Furthermore, since the unburned components in the combustion ash are reduced, when the combustion ash is used as a cement admixture, the hydration and hardening characteristics of the cement can be improved and the blending of cement and the like can be reduced. It can be used effectively as a material.

[2-4] Coal Combustion Method by Pulverized Coal Combustion Method First, 90 to 95% by mass of coal for combustion having a particle size of 80 mm or less, preferably 30 mm or less, and the methods of [1-1] and [1-2] above. Is mixed with 10 to 5% by mass of the coal combustion aid produced in step 1, and then the mixture is pulverized to the particle size of coal used in ordinary pulverized coal combustion, that is, the mixture has a particle size of 75 μm. It grind | pulverizes so that the following may be included including 70-80 mass% and a particle size of 250 micrometers or less. Next, this pulverized mixture is supplied to a pulverized coal combustion furnace and burned.

  When coal is burned by the method described in [2-4] above, the combustion promoting action of this coal combustion aid can reduce the unburned components in the combustion ash, and it is related to the unburned carbon in the combustion coal. It is possible to suppress the coarsening of the combustion ash and the combustion ash from becoming porous, and to improve the quality and strength of the combustion ash particles, that is, to impart self-hardness to the combustion ash particles. By preventing deterioration of the quality and strength of the combustion ash particles, it can be effectively used as a civil engineering material. In addition, among toxic components in combustion coal, volatile toxic components are fixed in combustion ash by calcium oxide derived from calcium carbonate, and their elution is suppressed, and in pulverized coal combustion, non-volatile toxic components are melted at high temperature. Since it is immobilized on combustion ash and made non-eluting, the properties of combustion ash can be improved. As a result, the combustion ash can be effectively used as a new civil engineering material such as a water-permeable ground material. In addition, by reducing the unburned components in the combustion ash and improving the chemical composition of the combustion ash, the polazone reactivity can be improved. Due to the improvement of the polyazone reactivity and the provision of the above-mentioned self-hardening property, a sufficient cement strength can be expressed with poor blending of about 5% by mass of cement. Also, the combustion-promoting coal in the coal-burning aid is instantaneously split and the coal-burning aid is uniformly dispersed, which can promote the combustion of nearby cloudy pulverized coal, and the ignitability and combustion of the combustion coal Can greatly improve performance. Furthermore, by improving the particle size composition for effective use of combustion ash, fine particles (submicron order) combustion ash can be collected efficiently, and in the combustion ash classification process, for example, combustion ash of 40 μm or less The yield can be greatly improved. As a result, the combustion ash can be effectively used as a civil engineering material such as cement admixture or concrete admixture.

  Next, examples of the present invention will be described in detail together with comparative examples.

<Example 1>
First, limestone as calcium carbonate is pulverized to a particle size of 75 μm or less, plant fiber beet fiber (biomass) is pulverized to a particle size of 1.0 mm or less, and combustion promoting coal is sized. Was pulverized so as to be 1.0 mm or less. Here, the moisture content of the beet fiber was 4%. Next, 80% by mass of the calcium carbonate and 20% by mass of the beet fiber were mixed in a mass ratio, and 50% by mass of the mixture and 50% by mass of combustion promoting coal were mixed. Furthermore, after curing this mixture at room temperature, it was molded under high pressure at a pressure of 240 MPa while being heated to 80 ° C. to produce a flat coal combustion aid. The coal combustion aid was disk-shaped with a diameter of 24.7 mm, a thickness of 3.0 mm, and a mass of 3 g. Next, this coal combustion aid was pulverized to a particle size of 1.0 mm or less and combustion coal having a particle size of 1.0 mm or less was mixed at a mass ratio of 10:90, and then the particle size was changed. Was pulverized so as to be 75 μm or less. This powder was referred to as Example 1. The combustion promoting coal and the combustion coal are Newlands coal (NL coal), and the composition thereof is shown in Table 1.

<Example 2>
A powder was prepared in the same manner as in Example 1 except that waste paper having a moisture content of about 16% was used as biomass, and this waste paper was crushed and crushed in water so that the particle size was 2.0 mm or less. . This powder was determined as Example 2.

<Example 3>
A powder was obtained in the same manner as in Example 1 except that wood (dry wood waste) having a moisture content of about 9% was used as biomass, and the wood was pulverized to a particle size of 1.0 mm or less. Prepared. This powder was determined as Example 3.

<Example 4>
A powder was prepared in the same manner as in Example 1 except that a lime cake containing calcium carbonate and biomass and having a water content of about 6% was crushed so that the particle size was 1.0 mm or less. . This powder was determined as Example 4. The lime cake was a dry matter-based mixture containing 88.3 mass% calcium carbonate and 11.7 mass% biomass.

<Example 5>
A powder was prepared in the same manner as in Example 4 except that Kushiro Coleman coal (KCM coal) was used as the combustion promoting coal. This powder was determined as Example 5. The composition of the Kushiro Coleman charcoal (KCM charcoal) is shown in Table 1.

<Comparative Example 1>
Fuel coal made of Newlands coal (NL coal) was pulverized so as to have a particle size of 75 μm or less. This powder was referred to as Comparative Example 1.

<Comparative test 1 and evaluation>
The combustion test of the powders of Examples 1 to 5 and Comparative Example 1 was performed. Specifically, air was flowed at a flow rate of 300 ml / min into a fluidized bed containing 0.5 g of powder, and the ignition temperature was measured by heating while the powder was flowing. At this time, the temperature that ignites inside the fluidized bed was defined as the ignition temperature. The results are shown in Table 2. Table 2 shows the mixing ratio of combustion coal and coal combustion aid, the mixing ratio of combustion promoting coal, calcium carbonate and biomass, and the mass ratio of biomass to calcium carbonate, along with the ignition temperature. .

  As is clear from Table 2, the ignition temperature in Comparative Example 1 was as high as 229.8 ° C., whereas in Examples 1 to 5, the ignition temperature was as low as 198.8 to 213.4 ° C. In Examples 1-5, since it is a temperature range in which calcium carbonate (thermal decomposition temperature: around 800 ° C.) is not involved at the temperature until the powder ignites, it is considered that the ignitability is improved by blending biomass. It is done. Moreover, in Examples 1-3, the effect of the fall of ignition temperature is acquired by the content rate of the biomass in coal combustion auxiliary | assistance with a small quantity as 1.0 mass%, and in Examples 4 and 5, the biomass in a lime cake is obtained. The effect of lowering the ignition temperature was obtained with a further small amount of 0.55% by mass.

<Example 6>
First, prepare a lime cake containing 88.3% by mass of calcium carbonate and 11.7% by mass of biomass on a dry matter basis and having a moisture content of 31%, so that the lime cake has a moisture content of 5%. And dried to a particle size of 1.0 mm or less. Next, this crushed material is formed into a binderless high-pressure molding at room temperature using a high-pressure roll press machine at a pressure of 200 MPa, and a coal combustion aid having a length and width of about 100 mm and a thickness of about 7 mm is continuously formed. After that, the mixture was pulverized to a diameter of 1 to 5 mm to prepare a coal combustion auxiliary (LCB) with a granular lime cake. Further, 95% by mass of combustion coal made of Newlands coal and 5% by mass of the coal combustion aid were mixed. This coal mixture (NL charcoal + LCB) was determined as Example 6.

<Example 7>
50% by mass of lime cake obtained by drying and pulverizing in the same manner as in Example 6 and 50% by mass of coal for combustion promotion consisting of Newlands coal pulverized to a particle size of 1.0 mm or less were mixed. This mixture was subjected to binderless high-pressure molding at room temperature using a high-pressure roll press at a pressure of 200 MPa, and a thin-layer flat coal combustion aid having a length and width of about 100 mm and a thickness of about 7 mm was continuously added. After being molded into a granulated coal combustion aid (NL CCI), it was pulverized to a diameter of 1 to 5 mm. Furthermore, 90% by mass of coal for combustion made of Newlands coal having a particle size of 0.25 to 5 mm and 10% by mass of the coal combustion aid were mixed. This coal mixture (NL charcoal + NL CCI) was taken as Example 7.

<Example 8>
A coal combustion aid (KCM CCI) having a diameter of 1 to 5 mm was produced in the same manner as in Example 7 except that Kushiro Coleman coal was used as the combustion promoting coal, and Newlands having a particle size of 0.25 to 5 mm. 90% by mass of combustion coal made of charcoal and 10% by mass of the coal combustion aid were mixed. This coal mixture (NL charcoal + KCM CCI) was taken as Example 8.

<Comparative example 2>
The combustion coal was pulverized to a particle size of 0.25 to 5 mm without adding a coal combustion aid to the combustion coal made of Newlands coal. This combustion coal (NL coal) was designated as Comparative Example 2.

<Comparative test 2 and evaluation>
Combustion tests were performed on the coal mixtures of Examples 6 to 8 and the combustion coal of Comparative Example 2 using a circulating fluidized bed combustion furnace. In this circulating fluidized bed combustion furnace, two cylindrical towers having an inner diameter of 100 mm and a height of 5.1 m are provided extending vertically, and the upper and lower parts of these towers are connected in communication. Composed. And while maintaining the temperature in a fluidized-bed combustion furnace at 850-60 degreeC and maintaining the oxygen concentration of the waste gas discharged | emitted from a combustion furnace at 4.0%, the coal mixture of Examples 6-8 and the comparative example 2 Combustion coal was supplied to the fluidized bed combustion furnace at a rate of 3 to 5 kg / hour and burned. The result is shown in FIG. Table 3 shows the average feed rates of the coal mixtures of Examples 6 to 8 and the combustion coal of Comparative Example 2. Furthermore, in Table 4, the supply rate of the coal mixture of Examples 6-8 is shown by the ratio when the supply rate of the combustion coal of Comparative Example 2 is 1.0.

  As is apparent from FIG. 5, in Examples 6 to 7, it was found that recovery from a rapid drop in the temperature in the combustion furnace was faster than that in Comparative Example 2, and that a high combustion temperature could be maintained throughout the combustion furnace. Further, as apparent from Table 3, in Comparative Example 2, the average supply rate (average supply amount per unit time) was as small as 3.41 kg / hour, while in Examples 6 to 8, the average supply rate ( The average supply amount per unit time) increased to 3.49 to 4.20 kg / hour. On the other hand, as is apparent from Table 4, the supply rate (kg / hour) of the supply rate in Example 8 increased 1.16 times that of Comparative Example 2, and the supply rate in Examples 6 and 7 was Comparative Example 2. Decreased to 0.97 times and 0.98 times, respectively. However, in Examples 6 and 7, 5% by mass and 10% by mass of LCB and NL-based CCI are added, respectively, so that the supply rate is substantially higher than that of Comparative Example 2.

<Comparative test 3 and evaluation>
The combustion mixture of Examples 6 to 8 and the combustion coal of Comparative Example 2 were subjected to a combustion test using a circulating fluidized bed combustion furnace, and unburned content contained in the combustion ash (fly ash) generated at this time The amount was measured. And combustion efficiency was calculated | required from the content rate (dry matter base) of the ash content in these coal mixtures. The results are shown in Table 5. Table 6 shows the desulfurization rate calculated from the SO ₂ concentration and NOx concentration generated when the coal mixtures of Examples 6 to 8 and the combustion coal of Comparative Example 2 are burned, and the SO ₂ concentration.

As is clear from Table 5, in Comparative Example 2, the unburned content was as high as 14.3% by mass, whereas in Examples 6 to 8, the unburned content was reduced to 4.9 to 8.7% by mass. It was. As is clear from Table 5, the combustion efficiency in Comparative Example 2 was as low as 96.8%, whereas in Examples 6 to 8, the combustion efficiency was as high as 97.7 to 98.8% by mass. . On the other hand, as apparent from Table 6, in Comparative Example 2, the SO ₂ concentration was as high as 130 ppm, while in Examples 6 to 8, the SO ₂ concentration was extremely low as 1 to 12 ppm. Thereby, in Examples 6-8, the desulfurization rate was very high with 91-99%, and it turned out that the effect by the composite coal combustion auxiliary of calcium carbonate and biomass containing especially coal for combustion promotion is large. Further, as apparent from Table 6, the NOx concentration in Comparative Example 2 was 120 ppm, whereas in Examples 6 to 8, the NOx concentration derived from coal volatiles was increased due to an increase in the amount of coal combustion per unit time. Although increased to 150 to 250 ppm, the NOx concentrations in Examples 6 to 8 were below the emission standard value (250 ppm or less).

<Comparative test 4 and evaluation>
The combustion mixture of Examples 6-8 and the combustion coal of Comparative Example 2 were subjected to a combustion test using a circulating fluidized bed combustion furnace as in Comparative Test 3, and combustion ash (fly ash) generated at this time The amount of harmful components (arsenic, boron, selenium and fluorine) contained in each was measured. The results are shown in Table 7. Table 7 shows the harmful components in the fine particulate cyclone ash (S ash) separated by the cyclone and the extremely fine particulate bag filter ash (B ash) collected in the bag filter. The harmful components were separately listed. Moreover, the generation ratio of the cyclone ash (S ash) and the bag filter ash (B ash) was 1: 1 by mass ratio.

  As is clear from Table 7, in Comparative Example 2, the fluorine in the cyclone ash (S ash) was as high as 1.0 mg / liter, whereas in Examples 6 to 8, the fluorine in the cyclone ash (S ash) was It decreased to 0.3 to 0.8 mg / liter. In Comparative Example 2, the amount of fluorine in the bag filter ash (B ash) was 23.7 mg / liter, whereas in Examples 6 to 8, the fluorine in the bag filter ash (B ash) was 1.2. It decreased to ˜4.4 mg / liter. Furthermore, about arsenic, boron, and selenium, it was found that Examples 6 to 8 and Comparative Example 2 were much lower than the soil environment standard, and the effect of suppressing elution of arsenic, boron, and selenium was great.

<Example 9>
The granular coal combustion aid (NL CCI) having a particle diameter of 1 to 5 mm in Example 7 was added to the combustion coal (NL coal) so as to have a mass ratio of 10: 100 and mixed and pulverized. . This mixed finely pulverized product was designated as Example 9. The particle size distribution of the mixed finely pulverized product was prepared so that 80% of the particles having a particle size of 75 μm or less existed, the maximum particle size was 150 μm, and the mass median diameter D _P 50 was about 40 μm.

<Example 10>
The granular coal combustion aid (KCM CCI) having a particle diameter of 1 to 5 mm in Example 8 was added to the combustion coal (NL coal) so as to have a mass ratio of 10: 100 and mixed and pulverized. . This mixed finely pulverized product was designated as Example 10. The particle size distribution of the mixed finely pulverized product was prepared so that 80% of the particles having a particle size of 75 μm or less existed, the maximum particle size was 150 μm, and the mass median diameter D _P 50 was about 40 μm.

<Comparative Example 3>
The combustion coal of Comparative Example 2 having a particle size of 0.25 to 5 mm was pulverized. This finely pulverized coal was used as Comparative Example 3. The particle size distribution of the finely pulverized coal was prepared such that 80% of the particles having a particle size of 75 μm or less existed, the maximum particle size was 150 μm, and the mass median diameter D _P 50 was about 40 μm.

<Comparative test 5 and evaluation>
Combustion tests were performed on the mixed finely pulverized products of Examples 9 and 10 and the finely pulverized coal of Comparative Example 3 using a pulverized coal combustion furnace. This pulverized coal combustion furnace has an inner diameter of 300 mm and a height of 2.8 m, and is a turbulent flow furnace simulating the combustion of an actual boiler (feed rate of mixed pulverized product or pulverized coal: 6 to 7 kg / hour) ). Also, the mixed finely pulverized product or finely pulverized coal is supplied into a furnace maintained at a temperature of 1450 ° C., and the front stage combustion air ratio becomes 0.9 by changing the blowing position and the amount of air of the second stage combustion air. A combustion test was performed under operating conditions such that the combustion air ratio was 0.35, the overall combustion air ratio was 1.25, and the oxygen concentration in the exhaust gas was 4.2%. And while measuring the content rate of the unburned component in the combustion ash obtained on the said operating condition, the unburned rate was computed, and the generation amount of NOx was measured. The relationship between the unburned rate and the amount of NOx generated is shown in FIG. Incidentally, the amount of NOx was carried out in O ₂ -6% conversion.

  As apparent from FIG. 6, in Comparative Example 3, the amount of NOx generated relative to the unburned rate was large, whereas in Examples 9 and 10, the amount of NOx generated relative to the unburned rate decreased. Combustion with reduced NOx emissions can be achieved without reducing the burn-off (unburned rate).

<Comparative test 6 and evaluation>
The mixed finely pulverized product of Examples 9 and 10 and the finely pulverized coal of Comparative Example 3 were subjected to a combustion test using a pulverized coal combustion furnace in the same manner as Comparative Test 5, and the combustion ash (fly ash) generated at this time was used. The amount of contained harmful components (hexavalent chromium, arsenic, selenium, boron and fluorine) in water was measured by the soil environment standard measurement method. The results are shown in Table 8.

  As is apparent from Table 8, for hexavalent chromium, arsenic, selenium and boron, both Example 9, Example 10 and Comparative Example 3 were below the soil environmental standards, and elution of hexavalent chromium, arsenic, selenium and boron was observed. It was found that there is an inhibitory effect. In particular, for hexavalent chromium and boron, both Examples 9 and 10 were significantly below the soil environmental standards, and it was found that the effect of suppressing elution of hexavalent chromium and boron was great. Moreover, regarding fluorine, although both exceeded the upper limit of 0.8 mg / liter of soil environmental standards, it was as high as 5.9 mg / liter in Comparative Example 3, whereas in Examples 9 and 10, it was 3. It decreased to 5 mg / liter and 5.0 mg / liter.

<Comparative test 7 and evaluation>
The content of fluorine contained in the mixed finely pulverized products of Examples 9 and 10 and the finely pulverized coal of Comparative Example 3 was analyzed by fluorescent X-ray. Further, the mixed finely pulverized product of Examples 9 and 10 and the finely pulverized coal of Comparative Example 3 were subjected to a combustion test using a pulverized coal combustion furnace in the same manner as in Comparative Test 5, and Example 9, Example 10 and Comparative Example were compared. The content of fluorine in the combustion ash of Example 3 was analyzed by fluorescent X-ray.

  As a result of the X-ray fluorescence analysis, the combustion ash of Comparative Example 3 could not detect fluorine due to its detection limit, whereas the combustion ash of Examples 9 and 10 was included in raw coal (combustion coal). A value close to the fluorine content was confirmed. Therefore, in Comparative Example 3, it is considered that the fluorine content in the raw coal (combustion coal) was attached to the combustion ash in such an amount that it could be detected as an elution component, and most of it was released to the atmosphere. On the other hand, in Examples 9 and 10, although a part of fluorine is eluted, most of the fluorine comes into contact with and reacts with calcium oxide derived from calcium carbonate in the coal combustion aid during combustion. It is thought that it was fixed to.

<Example 11>
The mixed finely pulverized product of Example 9 was mixed by adding 20% by mass of water to 80% by mass of combustion ash (FA) produced by combustion in a pulverized coal combustion furnace, and this mixture was disc at a low pressure of 0.1 MPa. Shaped tablets (mass: 3 g). This tablet was referred to as Example 11.

<Example 12>
A tablet was formed in the same manner as in Example 11 except that the finely mixed powder in Example 9 was replaced with the finely ground mixture in Example 10. This tablet was referred to as Example 12.

<Example 13>
20% by mass of water and 2% by mass of cement were added to and mixed with 78% by mass of combustion ash (FA) produced by combustion in a pulverized coal combustion furnace, and the mixture was mixed with 0.1 MPa. A disk-shaped tablet (mass: 3 g) was molded at a low pressure of 5 mm. This tablet was referred to as Example 13.

<Example 14>
A tablet was formed in the same manner as in Example 13, except that the finely mixed product of Example 9 was replaced with the finely mixed product of Example 10. This tablet was referred to as Example 14.

<Example 15>
20% by mass of water and 2% by mass of CaO were added to and mixed with 78% by mass of combustion ash (FA) produced by combustion in a pulverized coal combustion furnace with the mixed finely pulverized product of Example 9, and this mixture was mixed with 0.1 MPa. A disk-shaped tablet (mass: 3 g) was molded at low pressure. This tablet was referred to as Example 15.

<Example 16>
A tablet was formed in the same manner as in Example 15 except that the mixed finely pulverized product of Example 9 was replaced with the mixed pulverized product of Example 10. This tablet was referred to as Example 16.

<Comparative example 4>
A tablet was formed in the same manner as in Example 11 except that the mixed finely pulverized product of Example 9 was replaced with the finely pulverized coal of Comparative Example 3. This tablet was referred to as Comparative Example 4.

<Comparative Example 5>
A tablet was formed in the same manner as in Example 13, except that the mixed finely pulverized product of Example 9 was replaced with the finely pulverized coal of Comparative Example 3. This tablet was referred to as Comparative Example 5.

<Comparative Example 6>
A tablet was molded in the same manner as in Example 15 except that the mixed finely pulverized product of Example 9 was replaced with the finely pulverized coal of Comparative Example 3. This tablet was designated as Comparative Example 6.

<Comparative test 8 and evaluation>
The strength of the tablets of Examples 11 to 16 and Comparative Examples 4 to 6 was measured with a crushing tester. As shown in FIG. 7, this crushing tester is configured by attaching a spherical indenter 12 to the lower end of a cylinder 11 that can move up and down. The spherical indenter 12 was pushed into the tablet 13 and the load when the tablet 13 was cracked was defined as the strength of the tablet 13. The result is shown in FIG.

  As is clear from FIG. 8, in Comparative Example 4, the tablet strength was as low as 0.33 kg and did not show self-hardening, whereas in Examples 11 and 12, the tablet strength was 1.21 kg and 0.70 kg. It became high and exhibited self-hardness. In Comparative Example 5, the strength of the tablet was as low as 0.42 kg depending on the blending of cement, whereas in Examples 13 and 14, the strength of the tablet was as high as 1.68 kg and 1.40 kg. Furthermore, in Comparative Example 6, the tablet strength was as low as about 0.83 kg even when CaO was added, whereas in Examples 15 and 16, the tablet strength was as high as 1.23 kg and 1.30 kg. As is clear from the above results, the combustion ash obtained by burning the mixed finely pulverized products of Examples 11 to 16 is self-hardening and is hydrated and hardened with poor blending of cement or CaO (slight blending). Intensity due to sexual reaction was developed.

<Comparative test 9 and evaluation>
Combustion tests were performed on the mixed finely pulverized product of Example 9 and the finely pulverized coal of Comparative Example 3 using a pulverized coal combustion furnace, and the particle size distribution of the combustion ash was examined. FIG. 9 shows the particle size distribution of the combustion ash obtained by combustion of the finely pulverized coal of Comparative Example 3, that is, the combustion of only Newlands coal (NL coal). FIG. 10 shows the particle size distribution of combustion ash obtained by combustion of a mixed finely pulverized product of Lands coal (NL coal) and coal combustion aid (NL CCI).

  As is clear from FIG. 9, in Comparative Example 3, the unburned content is 7.0% (based on dry matter), the average particle size is about 17 μm, and the particle size distribution is as wide as 0.3 to 100.5 μm. As is apparent from FIG. 10, in Example 9, the unburned content decreased to 4.2% (dry matter basis), the average particle size was about 11 μm, and the particle size distribution was 0. It was distributed in a narrow range of .6 to 37.0 μm. From this, the reduction of fine particles (submicron particles) of combustion ash leads to an improvement in the dust collection effect, and a large shift of the particle size from the coarse particle side to the trickle side means that the particle size of the combustion ash is effective for effective use of the combustion ash It was found that the configuration could be improved.

Claims (6)

A powdery coal combustion aid composition used to add to combustion coal and containing calcium carbonate and biomass,
10-25 mass parts of said biomass is contained with respect to 100 mass parts of said calcium carbonate. The coal combustion adjuvant composition characterized by the above-mentioned.   The coal for combustion promotion is further included, and the total amount of the calcium carbonate and the biomass and the amount of the coal for combustion promotion are contained in a mass ratio of (90:10) to (25:75). Coal combustion aid composition.   A coal combustion aid formed by molding the powdery coal combustion aid composition according to claim 1 or 2 into a flat plate shape, a briquette shape or a granule shape.   The powdery coal combustion auxiliary composition according to claim 1 or 2 in a plate shape having a thickness of 15 mm or less and a length, width, or diameter of 100 mm or less at a pressure of 50 to 400 MPa, or 30 ml. A coal combustion aid formed into the following briquettes or formed by pulverizing these formations into granules having a particle size of 20 mm or less. A step of mixing 10 to 5% by mass of the coal combustion aid according to claim 3 or 4 with respect to 90 to 95% by mass of fuel coal having a particle size of 80 mm or less;
Supplying the mixture to a fluidized bed combustion furnace and combusting the mixture. The coal combustion aid according to claim 3 or 4 is mixed with 90 to 95% by mass of combustion coal having a particle size of 80 mm or less so as to contain 70 to 80% by mass of particles having a particle size of 75 μm or less. Crushing step;
Supplying the pulverized mixture to a pulverized coal combustion furnace and burning the mixture.

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