JP5941183B1 - Method for producing combustion aid for co-firing and combustion method for combustion coal using this combustion aid - Google Patents

Abstract

An object of the present invention is to accurately improve the ignitability and combustibility of combustion coal, thereby reducing unburned components contained in combustion ash (fly ash) and improving combustion efficiency. A combustion aid for mixed combustion is mixed with combustion coal and used to assist combustion of the combustion coal. The combustion aid for co-firing is formed by extruding a mixture of paper sludge crushed and dehydrated and then crushed and coal powder into a rod shape of a predetermined length, and then cutting and drying the molded product. It is a stick-shaped dry molded product obtained in this way. [Selection] Figure 1

Description

The present invention relates to a method for producing a mixed combustion combustion aid for improving the combustibility of combustion coal, and a combustion method for combustion coal using the combustion aid. More specifically, a method for producing a combustion aid for mixed combustion obtained by mixing paper sludge and coal powder that has been dewatered and mixed with coal powder (including low-pressure molding) or high-pressure molding, and mixing the combustion aid for mixed combustion with combustion coal. The present invention relates to a method of burning this coal for combustion by performing treatment or mixing / pulverization treatment.

  Conventionally, in order to improve the combustibility of coal powder, the technology of burning (ie, exclusively burning) coal powder alone is improved, and coal powder and biomass powder that is wood powder of pine, cedar, oak, etc. are mixed. A technique for burning (that is, co-firing) is disclosed (for example, see Non-Patent Document 1). In this Non-Patent Document 1, as a method for co-firing pulverized coal that is coal powder with biomass in a pulverized coal-fired boiler, a single pulverization method that pulverizes biomass alone and mixed pulverization that mixes and pulverizes biomass and coal. The method is shown. In the above single pulverization method, pulverized coal obtained by finely pulverizing coal is supplied to a pulverized coal-fired boiler in a pulverized coal combustion furnace, and at the same time, biomass powder obtained by finely pulverizing biomass is supplied to the pulverized coal combustion furnace. In pulverized coal and biomass powder are mixed and burned. In the mixed pulverization method, coal and biomass are mixed and then pulverized, supplied to a pulverized coal combustion furnace, and burned. In the above-mentioned single pulverization method, it is necessary to install a pulverizer or burner dedicated to biomass. By mixing coal and biomass on the conveyor for transportation, existing pulverized coal machines and pulverized coal burners can be used, so there is little additional equipment and there is little impact on power in the power plant.

  However, in the mixed combustion technology using the above-mentioned mixed pulverization method, wood and coal are simultaneously pulverized with a pulverized coal machine, so the power load on the pulverized coal machine is large and the mixing rate of wood cannot be increased. There is. As an improvement technique of this co-firing technique, a coal combustion method is disclosed in which coal powder obtained by pulverizing coal, biomass carbide powder obtained by carbonizing a plant-derived biomass material, and vinegar are mixed and supplied to a combustion apparatus. (For example, refer to Patent Document 1). According to this method, coal powder, biomass carbide powder, and vinegar liquid are mixed and mixed, so that calcium that is an ash component of coal and further calcium that is an ash component of biomass carbide is dissolved in the vinegar liquid. Is uniformly dispersed and supported on the surface of coal powder and biomass carbide powder so as to exhibit combustion catalytic activity. In Patent Document 1, as an effect of the invention, the combustibility can be improved as compared with the case where the coal powder is burned (i.e., exclusively burned), and the coal powder and the biomass carbide powder are mixed and burned (i.e. It is described that flammability can be improved as compared with the case of co-firing, and at the same time, the amount of carbon dioxide emission can be reduced.

  On the other hand, solid fuel made by mixing paper sludge (paper sludge) and low-quality coal pulverized coal (coal powder) as a fuel technology by mixing paper sludge and coal powder (for example, patent documents) 2), and a method for making a pulverized fuel (see, for example, Patent Document 3) in which a waste organic substance having a high water content such as paper sludge and a heat-generating auxiliary material such as coal powder are mixed to produce a pulverized fuel. ing. The solid fuel shown in Patent Document 2 is produced by kneading low-quality coal pulverized coal, paper sludge, oil sludge, and slaked lime, and solidifying the mixture. According to this solid fuel, slaked lime reacts with sulfur in paper sludge and oil sludge to prevent its sulfurous acid gasification, and effectively uses paper sludge that has become a pollution source by dumping, and generates heat. Low quality coal can be burned.

  Also, in the method for converting to powder fuel shown in Patent Document 3, paper sludge, which is a waste organic substance with a high water content, is dried to form a dry waste organic substance, and then this dry waste organic substance is put into a mixer and water-soluble heat such as poval is added. An appropriate amount of a plastic resin and a heat-generating auxiliary material such as coal powder that removes residual moisture by absorbing residual moisture in the dried waste organic matter is mixed and mixed to make a powder fuel raw material. The fueled raw material is further put into a hopper of an extrusion molding machine, heated, pressurized, kneaded and extruded into a stick shape to form a short columnar combustible raw material. Further, the short columnar combustible raw material is put into a crusher and made into a fine powder. Powdered fuel is obtained by crushing. According to this method for converting to powder fuel, powder that retains high thermal energy so that dioxins are not generated even when discarded and burned by powerfully removing moisture from water-containing waste organic matter such as paper sludge and making it odor-free. Fuel can be produced.

Emi Ohno et al. “Biomass utilization technology in pulverized coal-fired boilers”, Ishikawajima-Harima Technical Report Vol.44 No.6 (2004-11)

JP2013-11377A (Claim 1, Claim 2, Paragraph [0035]) Japanese Patent Application Laid-Open No. 55-12117 (Claims, page 1, left column, line 14 to page 17, right column, line 17) JP 2003-138282 A (Claim 1, paragraph [0003])

  However, in the coal combustion method disclosed in Patent Document 1, since vinegar, which is one of coal powder combustion aids, is a strongly acidic aqueous solution, it is easy to corrode the liquid feed pump that supplies the vinegar and its piping. In addition, there is a problem that the working environment is liable to be deteriorated by the odor generated from the vinegar.

  Moreover, the solid fuel shown in Patent Document 2 and the pulverized fuel shown in Patent Document 3 are literally used as fuels and are not used for the purpose of improving the combustibility of combustion coal. In the case where the solid fuel shown in Patent Document 2 is used as a combustion aid for combustion coal, the solid fuel requires oil sludge and slaked lime, and there is a problem that the components of the solid fuel increase. is there. In addition, regarding the papermaking sludge constituting the solid fuel shown in Patent Document 2, any water content or sludge shape / size may be used, and the blending amount with low quality coal is not specified. There is also a problem that the combustibility of combustion coal cannot be improved accurately when solid fuel is mixed and burned with combustion coal.

  In addition, when the powder fuel shown in Patent Document 3 is used as a combustion aid for combustion coal, the powder fuel requires a water-soluble thermoplastic resin such as poval, and the composition of the powder fuel. There is a problem that the component increases. Furthermore, the dry waste organic paper sludge constituting the pulverized fuel shown in Patent Document 3 may have any moisture content, sludge form / size, and the amount of coal sludge is specified. Therefore, there is a problem that the combustibility of the combustion coal cannot be improved accurately when this powder fuel is mixed and burned with the combustion coal.

The first object of the present invention is to improve the ignitability and combustibility of combustion coal accurately, thereby reducing the unburned content contained in the combustion ash (fly ash) and increasing the efficiency of combustion. An object of the present invention is to provide a method for producing a combustion aid for co-firing and a method for burning combustion coal using the same.

The second object of the present invention is that, when mixed with combustion coal and combusted, it can be burned with low NOx by improving its combustibility, and the calcium carbonate in the paper sludge contains sulfur content in the combustion coal. A method for producing a combustion aid for co-firing that can absorb and react efficiently and that can be treated in a combustion furnace, unlike the conventional NOx / SOx reduction method by wake treatment. It is providing the combustion method of the coal for combustion using this.

According to a third object of the present invention, when mixed with combustion coal and combusted, calcium carbonate in the paper sludge reacts with a trace amount of harmful metal components in the combustion coal to immobilize this component, and It can be reduced unburned ash through improved flammability, effective use of fly ash, can improve its properties and particle size configuration and the like, preparation and combustion coal using the same co-firing combustion aid It is to provide a combustion method.

The fourth object of the present invention is to synthesize paper biomass of papermaking waste in the form of a combustion aid for mixed firing, and to synthesize fiber biomass such as cellulose and lignin as main components contained therein, and As described above, calcium carbonate provides a multifaceted effect on pulverized coal combustion as a combustion aid as described above. On the other hand, high-efficiency thermal recycling is achieved from the thermal energy of clean biomass that occupies 2-3% by mass of paper sludge. It is an object of the present invention to provide a method for producing a combustion aid for mixed combustion and a method for burning combustion coal using the same.

A first aspect of the present invention is a method for producing a co-firing combustion aid for mixing with combustion coal and assisting combustion of the combustion coal, which is squeezed, dewatered and then crushed paper sludge and after the mixture obtained by mixing the coal powder was extruded into bars of predetermined length, and a water content to produce a stick of dry molding 7 to 10 percent by dry cutting the molded product, the The dry molded product is further compression-molded at a predetermined pressure without a binder to form a plate or almond .

According to a second aspect of the present invention, a coal for combustion having an average particle diameter of 50 mm or less and a combustion aid for mixed combustion produced by the method described in the first aspect are mixed with respect to 100% by mass of the coal for combustion. A step of preparing a mixture by mixing so that the combustion auxiliary agent is in a proportion of 3 to 25% by mass, and this mixture is a fluidized bed furnace, a circulating fluidized bed coal combustion furnace, a moving bed coal combustion furnace, an incinerator Or it is the combustion method of the coal for combustion including the process of supplying and burning to a gasification combustion furnace.

According to a third aspect of the present invention, a combustion coal having an average particle diameter of 50 mm or less and a combustion aid for mixed combustion produced by the method described in the first aspect are mixed with 100% by mass of combustion coal. A step of preparing a mixture by mixing so that the combustion auxiliary agent is in a proportion of 3 to 25% by mass, and this mixture is a fluidized bed furnace, a circulating fluidized bed coal combustion furnace, a moving bed coal combustion furnace, an incinerator Or it is the combustion method of the coal for combustion including the process of supplying and burning to a gasification combustion furnace.

According to a fourth aspect of the present invention, a combustion coal having an average particle size of 50 mm or less and a combustion aid for mixed combustion produced by the method described in the first aspect are mixed with respect to 100% by mass of the combustion coal. A step of preparing a mixture by mixing so that the combustion aid is in a ratio of 3 to 25% by mass, a step of preparing a mixed and finely pulverized product by finely pulverizing the mixture, A method for burning combustion coal, including a step of supplying a pulverized product to a pulverized coal combustion furnace and burning the pulverized product.

According to a fifth aspect of the present invention, a combustion coal having an average particle size of 50 mm or less and a combustion aid for mixed combustion produced by the method described in the first aspect are mixed with respect to 100% by mass of the combustion coal. A step of preparing a mixture by mixing so that the combustion aid is in a ratio of 3 to 25% by mass, a step of preparing a mixed and finely pulverized product by finely pulverizing the mixture, A method for burning combustion coal, including a step of supplying a pulverized product to a pulverized coal combustion furnace and burning the pulverized product. In the present specification, the average particle size in the powders of combustion coal, paper sludge, synthetic calcium carbonate and the like refers to the average particle size based on the number distribution, and is the average particle size of 200 powders.

  The combustion aid for co-firing according to the first aspect of the present invention is obtained by extruding a mixture of paper sludge crushed and dewatered and then crushed and coal powder into a rod shape having a predetermined length, and then forming the molded product. This is a stick-shaped dry molded product obtained by cutting and drying, so that the moisture content of the combustion aid for mixed combustion becomes low, and the ignitability and combustibility of combustion coal mixed with this combustion aid for mixed combustion Can be improved accurately. As a result, it is possible to reduce the unburned content contained in the combustion ash (fly ash) and to improve the combustion efficiency of the combustion aid for mixed combustion and the coal for combustion.

The paper sludge contains fibrous biomass such as cellulose and lignin, synthesized calcium carbonate, kaolin mineral, etc., and the dried fibrous biomass has a low moisture content and a high volatile content. Therefore, combustion coal with a small amount of volatile matter can be efficiently co-fired by long flame combustion (evaporative combustion) of this fibrous biomass. As a result, the efficiency of the boiler such as the circulating fluidized bed coal combustion furnace can be improved, and an energy saving effect can be achieved. Further, more complete heat utilization of the fibrous biomass is possible, that is, heat recovery (thermal recycling) corresponding to the amount of fibrous biomass used is possible, so that the amount of combustion coal used can be reduced. In addition, calcium oxide derived from ultrafine synthetic calcium carbonate contained in the paper sludge reacts with harmful components such as sulfur in the combustion coal to immobilize this harmful component, and the harmful component atmosphere in the combustion coal In addition to being able to suppress the release into the interior, the catalytic action of calcium oxide derived from the synthetic calcium carbonate can improve the combustion characteristics or gasification characteristics of the combustion coal, thereby being contained in the combustion ash (fly ash) Unburned components can be reduced. In this specification, “synthetic calcium carbonate” refers to the former quick lime (CaO) among quick lime (CaO) and carbon dioxide (CO ₂ ) obtained by firing limestone (CaCO ₃ ) at 1100 ° C. Carbon dioxide (CO ₂ ) is blown into a slaked lime (Ca (OH) ₂ ) suspension and reacted to react with the newly synthesized CaCO ₃ . “Synthetic calcium carbonate” is sometimes called light calcium carbonate or precipitated calcium carbonate, as distinguished from heavy calcium carbonate crushed from limestone. However, in this specification, although the synthetic calcium carbonate contained in the paper sludge is described, the paper sludge usually contains heavy calcium carbonate in addition to the synthetic calcium carbonate, so the calcium carbonate in the paper sludge is: It may be synthetic calcium carbonate, heavy calcium carbonate, or both synthetic and heavy calcium carbonate.

Furthermore, the combustion aid for co-firing according to the first aspect of the present invention has a moisture content of 7 to 10% in a dry molded product, and the dry molded product is further compression-molded at a predetermined pressure without a binder. Since it is shaped like an almond, it can be formed to a certain quality, shape and size, and it can withstand transportation and handling, etc. It becomes possible to supply directly to the burner combustion furnace through mixing and pulverization. This combustion aid for mixed firing enables high-order recycling of industrial waste paper sludge discharged in large quantities from many paper mills across the country.

In the combustion coal combustion method according to the second aspect of the present invention, the combustion coal having an average particle size of 50 mm or less and the combustion aid for mixed combustion produced by the method according to the first aspect are used. Since a mixture is prepared by mixing so that the combustion aid for mixed combustion becomes a ratio of 3 to 25% by mass with respect to 100% by mass, and this mixture is supplied to a circulating fluidized bed coal combustion furnace or the like and burned, Combustion coal can be burned with NOx in the exhaust gas reduced, and sulfur content can be removed efficiently from the combustion coal by absorption and reaction of calcium carbonate in the paper sludge. Unlike the NOx and SOx reduction methods, it offers the possibility of in-combustion treatment. Also, with this combustion method, when mixed combustion aids are mixed with combustion coal and burned, calcium carbonate in the paper sludge reacts with trace amounts of harmful metal components in the combustion coal to fix this component. In addition, it is possible to reduce the unburned content in the combustion ash (fly ash) by improving the combustibility and to effectively use the combustion ash (fly ash), and to improve the properties, the particle size constitution, and the like. Furthermore, during mixed combustion in a circulating fluidized bed coal combustion furnace (combustion temperature of about 850 ° C), low-temperature sintering and coarsening of combustion ash (fly ash) enables efficient collection of coarse cyclone ash by high-temperature cyclone, and low-temperature combustion Can promote the reactivity of pozzolanic to combustion ash (fly ash). Here, the pozzolanic reaction is calcium hydroxide produced by the hydration reaction of silicon dioxide contained in combustion ash (fly ash) when water is added after mixing the combustion ash (fly ash) with cement. Reaction to produce a dense and durable calcium silicate hydrate.

In the combustion method for combustion coal according to the third aspect of the present invention, combustion coal having an average particle size of 50 mm or less and the combustion aid for mixed combustion produced by the method according to the first aspect are used. Since a mixture is prepared by mixing so that the combustion aid for mixed combustion becomes a ratio of 3 to 25% by mass with respect to 100% by mass, and this mixture is supplied to a circulating fluidized bed coal combustion furnace or the like and burned, In addition to the effects of the combustion method of the third aspect, the effects of the combustion method of the second aspect can be obtained.

In the combustion coal combustion method of the fourth aspect of the present invention, the combustion coal having an average particle size of 50 mm or less and the combustion aid for mixed combustion produced by the method described in the first aspect are used. A mixture is prepared by mixing so that the combustion aid for mixed firing is in a ratio of 3 to 25% by mass with respect to 100% by mass, and the mixture is pulverized to prepare a mixed and finely pulverized product. Since this mixed and finely pulverized product is supplied to the pulverized coal combustion furnace and combusted, when the co-firing combustion aid is mixed with the flame-retardant combustion coal and pulverized, it is uniformly dispersed in the pulverized coal. Is supplied to the combustion furnace. As a result, a combined combustion field is formed by mixing and finely pulverized product in the pulverized coal combustion furnace, and fine particles derived from the composition of the combustion coal fine particles (pulverized coal) and the mixed combustion combustion aid in the combustion field As a result of this interaction, it is possible to improve the combustibility in the pulverized coal combustion furnace, which cannot be expected by burning only the fine particles (pulverized coal) of the combustion coal, and to reduce NOx and SOx in the exhaust gas. In addition, the new mineralogical composition added together with calcium carbonate during co-firing in a pulverized coal combustion furnace (combustion temperature of about 1450 ° C.) can improve the properties and particle size composition of combustion ash (fly ash), and the mineralogical composition described above. Can promote pozzolanic reactivity to high-temperature combustion ash (fly ash).

In the combustion coal combustion method according to the fifth aspect of the present invention, the combustion coal having an average particle size of 50 mm or less and the combustion aid for mixed combustion produced by the method according to the first aspect are used. A mixture is prepared by mixing so that the combustion aid for mixed firing is in a ratio of 3 to 25% by mass with respect to 100% by mass, and the mixture is pulverized to prepare a mixed and finely pulverized product. Since the mixed and finely pulverized product is supplied to the pulverized coal combustion furnace and combusted, the effect of the combustion method of the fourth aspect can be obtained in addition to the effect of the combustion method of the fifth aspect.

It is a flowchart which shows the process of manufacturing the combustion adjuvant for mixed combustion of this invention embodiment, and the process of burning the coal for combustion using this combustion adjuvant. It is the schematic of a circulating fluidized bed coal combustion furnace. It is the schematic of a small pulverized coal combustion furnace. It is a figure which shows the change of the moisture content with respect to time passage of the mixed molding of Example 1, the paper sludge of Comparative Example 1, and the KCM charcoal of Comparative Example 2. It is a figure which shows the SOx density | concentration and desulfurization rate in exhaust gas by the mixed combustion of the mixed fuel of Examples 4-6, and the combustion of the single fuel of the comparative example 3. It is a figure which shows the NOx density | concentration in the waste gas by the mixed combustion of the mixed fuel of Examples 4-6 and the combustion of the single fuel of the comparative example 3. FIG. (A) is a figure which shows the particle size distribution of the bag ash obtained by the mixed combustion of the mixed fuel of Example 4, and the combustion of the single fuel of the comparative example 3, (b) is the mixed combustion of the mixed fuel of Example 4. 4 is a graph showing the particle size distribution of cyclone ash obtained by combustion of a single fuel in Comparative Example 3. FIG. (A) is a figure which shows the particle size distribution of the bag ash obtained by the mixed combustion of the mixed fuel of Example 6, and the combustion of the single fuel of the comparative example 3, (b) is the mixed combustion of the mixed fuel of Example 6. 4 is a graph showing the particle size distribution of cyclone ash obtained by combustion of a single fuel in Comparative Example 3. FIG. It is a microscope picture figure of the cyclone ash obtained by co-firing of the mixed fuel of Examples 4-6 and combustion of the single fuel of the comparative example 3. It is a figure which shows the crushing strength of the cement hardening body using the cyclone ash and bag ash obtained by the mixed combustion of the mixed fuel of Examples 4-6 and the combustion of the single fuel of the comparative example 3. It is a figure which shows the NOx density | concentration in the waste gas by combustion of the finely pulverized mixed fuel of Examples 7 and 8 and combustion of the finely pulverized single fuel of Comparative Example 4. It is a figure which shows the particle size distribution of the combustion ash obtained by the co-firing of the finely pulverized mixed fuel of Example 7 and the combustion of the finely pulverized single fuel of Comparative Example 4. It is a figure which shows the crushing strength of the cement hardening body using the combustion ash obtained by combustion of the finely pulverized mixed fuel of Examples 7 and 8 and combustion of the finely pulverized single fuel of Comparative Example 4.

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

  The combustion aid for mixed combustion of the present invention is used for mixing with combustion coal and assisting combustion of the combustion coal. The combustion aid for co-firing of the present invention is a stick-shaped dry molded product obtained by mixing paper sludge and coal powder and extrusion-molding it into a rod shape, and then cutting and drying this molded product.

<Characteristics of paper sludge and raw paper sludge>
The paper sludge of the present invention is a compression molded product having a water content of 45 to 60% obtained by pressing and dehydrating slurry having a concentration of 4 to 8% discharged from the papermaking process at a pressure of 2.5 to 4.0 MPa. The raw paper sludge differs depending on the raw pulp used in the papermaking process, but when the entire sludge is 100% by mass, the cellulose / lignin fiber is 25-50% by mass, and the synthetic calcium carbonate is 25-35% by mass. And 15-25% by mass of kaolin mineral and the like. That is, the paper sludge of the present invention is an aggregate of fine particles such as calcium carbonate and kaolin mineral (kaolinite clay mineral) that are electrically coupled to the wood sludge while containing many wood fibers. Although the paper sludge before drying is an organic sludge having a high water content, it has excellent drying characteristics in a low temperature range (for example, 25 to 50 ° C.), that is, air drying characteristics, compared to general organic sludge. It has characteristics as a raw material for combustion aids for mixed combustion.

<Coal powder>
The coal types used in the coal powder contained in the combustion aid for mixed combustion of the present invention are sub-bituminous and bituminous coals having a fuel ratio (industrial analysis: fixed carbon / volatile content) of domestic and foreign coals of around 1.0. In terms of charcoal, it is desirable to be a non-caking coal having excellent gasification reactivity and deep combustibility, and a relatively good quality with low ash content and low sulfur content. As coal corresponding to this quality, there is Kushiro coal mine coal (hereinafter referred to as KCM coal), the only underground production in Japan, and it is difficult to secure such coal types in terms of price and quantity for overseas coal. It is in. Among them, as a coal that can be easily procured instead of the above-mentioned coal types, mixed combustion to support the combustion of flame retardant combustion coal for overseas steam coal with a fuel ratio of about 1.5 to 2.0 It can be used as a raw material for combustion aids. In particular, the above KCM coal is a coal having extremely low combustible sulfur content, high boiler efficiency in a circulating fluidized bed coal combustion furnace and the like, and excellent gasification characteristics. The coal powder should be pulverized with a pulverized coal machine such as a hammer mill so that the average particle size is 2.0 mm or less, and air-dried or heat-dried to adjust the moisture content to 5 to 10%. Is obtained. If the average particle diameter of the coal powder exceeds 2.0 mm, the crushing strength of the molded product obtained by mixing paper sludge and coal powder and molding at high pressure becomes lower than the desired value, so that it cannot withstand storage, handling, transportation and the like. On the other hand, if the moisture content is less than 5% or exceeds 10%, the crushing strength of the molded product becomes lower than a desired value, and it cannot withstand storage, handling, transportation and the like.

<Combustion aid 1 for co-firing consisting of a composite molding of paper sludge and coal powder>
The paper sludge and the coal powder are mixed with paper sludge: coal powder in a mass ratio within the range of (4: 6) to (6: 4) to prepare a mixture, and the mixture is formed into a rod shape having a diameter of 5 to 30 mm. After extrusion molding, it is cut into a length of 10 to 30 mm and dried to produce a stick-shaped dry molded product. Thereby, the combustion aid 1 for mixed combustion is obtained. The moisture content of the dried stick-shaped dry molded product is preferably in the range of 7 to 10%. Moreover, you may form in the pellet form of diameter 5-10mm by carrying out the low-pressure shaping | molding of the said dried stick-shaped dry molding with a die | dye without a binder. Here, the paper sludge: coal powder was limited to a mass ratio within the range of (4: 6) to (6: 4) because of the types of raw materials in the mixed combustion combustion aid and the mixed combustion combustion aid. The mixing ratio is appropriately set depending on the purpose of use. Further, the moisture content of the stick-shaped dry molded product is limited to the range of 7 to 10% because the crushing strength of the combustion aid 1 for co-firing becomes lower than a desired value when the content is less than 7%, storage, handling, It is because it cannot endure transportation etc., and if it exceeds 10%, the effect as a combustion aid for mixed combustion, that is, the effect of improving the combustibility of combustion coal is reduced.

<Characteristics of combustion aid 1 for mixed firing>
The mixed combustion combustion aid 1 has a low moisture content, and can improve the ignitability and combustibility of the combustion coal mixed with the mixed combustion combustion aid 1. As a result, it is possible to reduce the unburned content contained in the combustion ash (fly ash) and to improve the combustion efficiency of the combustion aid for mixed combustion and the coal for combustion. In addition, since the fibrous biomass contained in the paper sludge in the mixed combustion combustion aid 1 has a low moisture content and a large amount of volatile matter, the combustion of the fibrous biomass with a small amount of volatile matter is caused by the long flame combustion (evaporative combustion). Coal fire can be efficiently mixed. As a result, the efficiency of the boiler such as the circulating fluidized bed coal combustion furnace can be improved, and an energy saving effect can be achieved. Further, more complete heat utilization of the fibrous biomass is possible, that is, heat recovery (thermal recycling) corresponding to the amount of fibrous biomass used is possible, so that the amount of combustion coal used can be reduced. In addition, calcium oxide derived from ultrafine synthetic calcium carbonate contained in the paper sludge reacts with harmful components such as sulfur in the combustion coal to immobilize this harmful component, and the harmful component atmosphere in the combustion coal In addition to being able to suppress the release into the interior, the catalytic action of calcium oxide derived from the synthetic calcium carbonate can improve the combustion characteristics or gasification characteristics of the combustion coal, thereby being contained in the combustion ash (fly ash) Unburned components can be reduced.

<Combustion aid 2 for co-firing consisting of high-pressure molding of paper sludge and coal powder>
The above-mentioned dried stick-shaped dry molding is continuously high-pressure molded into a plate or briquette at a pressure (linear pressure) of 3 to 5 tons / cm using a double roll molding machine without a binder. As a result, the dried molded product is subjected to high-pressure composite granulation to obtain a combustion aid 2 for mixed firing. One of the high pressure molding characteristics is that it can be manufactured with high productivity. In addition, dry molded products that have already been consolidated by extrusion molding are further consolidated while maintaining good degassing conditions under high pressure in the high-pressure granulation process, and the wood fibers contained therein are molded. It acts greatly as a material reinforcing material, and its crushing strength is improved, and water resistance is also improved. Here, if the pressure of the high pressure molding is less than 3 ton / cm, a desired strength cannot be obtained in the molded product, and the molded product tends to collapse during transportation or handling. Further, even if the pressure of high pressure molding exceeds 5 ton / cm, the strength of the molded product does not increase so much.

<Characteristics of combustion aid 2 for mixed firing>
The combustion aid 2 for mixed combustion can be formed in a certain quality, shape and size, and is strong enough to withstand transportation and handling, and its fine pulverization property. It becomes possible to supply directly to the burner combustion furnace through mixing and pulverization. Moreover, the combustion aid 2 for mixed firing enables high-order recycling of paper sludge of industrial waste discharged in large quantities from many paper mills across the country.

  <Combustion method of coal for combustion>

[1] Combustion method of mixture of combustion aid 1 for co-firing and coal for combustion (FIG. 1)
Combustion coal with an average particle size of 50 mm or less and stick-like or pellet-like combustion aid 1 for mixed combustion A ratio of 3 to 25% by mass of combustion aid 1 for mixed combustion with respect to 100 mass% of combustion coal Prepare a mixture by mixing. Then, this mixture is supplied to a fluidized bed furnace, a circulating fluidized bed coal combustion furnace, a moving bed coal combustion furnace, an incinerator or a gasification combustion furnace and burned. As a result, combustion coal can be burned with NOx in the exhaust gas reduced, and sulfur from the combustion coal can be efficiently removed by absorption and reaction of calcium carbonate in the paper sludge. Unlike the method for reducing NOx and SOx by treatment, efficient in-furnace treatment is possible. In this combustion method, when the combustion aid for mixed combustion is mixed with combustion coal and burned, calcium oxide derived from calcium carbonate in the paper sludge reacts with a trace amount of harmful metal components in the combustion coal. By immobilizing this component and improving its combustibility, it is possible to reduce the unburned content in the combustion ash (fly ash), effectively use the combustion ash (fly ash), and improve its properties, particle size constitution and the like. Furthermore, during mixed combustion in a circulating fluidized bed coal combustion furnace (combustion temperature of about 850 ° C), low-temperature sintering and coarsening of combustion ash (fly ash) enables efficient collection of coarse cyclone ash by high-temperature cyclone, and low-temperature combustion Can promote the reactivity of pozzolanic to combustion ash (fly ash). Here, if the combustion aid 1 for mixed combustion is less than 3% by mass, the gasification performance improvement effect by the combustion aid for mixed combustion is influenced by the amount of biomass, calcium carbonate, etc. in the combustion aid, and composite gas. Gasification reactivity due to the interaction in the gasification field decreases, the melting point of the combustion ash increases, and gasification performance decreases. In addition, when the mixed combustion combustion aid 1 is 10% by mass with respect to 100% by mass of the flame-retardant combustion coal, the desired ignitability and combustibility can be improved. If it exceeds 50%, it cannot be expected that the gasification performance will be improved enough to be economical.

  The fluidized bed furnace is a furnace that burns fuel in high-temperature sand that has been fluidized by blowing up pressurized air from the bottom upward. As shown in FIG. 2, the circulating fluidized bed coal combustion furnace 10 includes a combustion furnace body 13, a primary cyclone 11, and a loop seal 14, and a fluidizer (fine alumina etc.) 17 along with a high-speed gas flow. Circulates between the combustion furnace main body 13, the primary cyclone 11 and the loop seal 14 together with the fuel 16, and the fuel 16 burns during this circulation. The fluidizer (fine alumina etc.) 17 descends into the loop seal 14 by its own weight from the primary cyclone 11 and circulates in the furnace, and the exhaust gas is discharged from the upper end of the primary cyclone 11 to the secondary cyclone 12. Inflow. The relatively heavy ash (cyclone ash) in the exhaust gas is collected by the secondary cyclone 12, and the exhaust gas discharged from the upper end of the secondary cyclone 12 passes through the gas cooler 18 and the bag filter 19 and is blown into the atmosphere by the blower 21. To be discharged. Note that relatively light ash (bug ash) is collected by the bag filter 19. Moreover, the code | symbol 22 in FIG. 2 is a hopper which stores the fuel 16, and the code | symbol 23 is a preheater. In addition, the moving bed (stalker) type coal combustion furnace is a furnace that burns while moving fuel on a stalker that is a staircase grate. Incinerators include various large and medium incinerators. Further, a gasification combustion furnace is a furnace configured to burn a part of fuel in a primary furnace to generate a combustible gas and to burn the combustible gas in a secondary furnace.

[2] Combustion method of mixture of combustion aid 2 for co-firing and coal for combustion (FIG. 1)
Combusting coal having an average particle size of 50 mm or less and the co-firing combustion aid 2 are mixed so that the co-firing combustion aid 2 is in a ratio of 3 to 25 mass% with respect to 100 mass% of the combustion coal. Prepare the mixture by Then, this mixture is supplied to a fluidized bed furnace, a circulating fluidized bed coal combustion furnace, a moving bed coal combustion furnace, an incinerator or a gasification combustion furnace and burned. Thereby, the effect by the combustion method of the mixture of the combustion aid 1 for co-firing and the coal for combustion of [1] is obtained. Moreover, the combustion aid 2 for co-firing can be molded to a certain quality, shape and size, and can be used for combustion coal in existing pulverization facilities of pulverized coal-fired power plants because of its strength that can withstand transportation and handling and its fine pulverization properties. It becomes possible to supply to the burner combustion furnace directly after mixing and pulverizing. Here, the reason why the combustion aid 2 for co-firing is limited to the range of 3 to 25 mass% with respect to 100 mass% of the coal for combustion is that the combustion aid 1 for co-firing is 3 with respect to 100 mass% of the coal for combustion. It is the same as the reason limited within the range of ˜25% by mass.

[3] Combustion method of co-firing combustion aid 1 and combusting coal and combustion of finely pulverized product (Fig. 1)
By mixing the combustion coal having an average particle size of 50 mm or less and the combustion aid 1 for mixed combustion so that the combustion aid for mixed combustion becomes 3 to 25 mass% with respect to 100 mass% of combustion coal. A mixture is prepared, and this mixture is pulverized to prepare a mixed and pulverized product. Then, the mixed and finely pulverized product is supplied to the pulverized coal combustion furnace and burned. As a result, when the co-firing combustion aid 1 is mixed with the flame-retardant combustion coal and pulverized, it is supplied to the combustion furnace in a state of being uniformly dispersed in the pulverized coal. As a result, a composite combustion field is formed by mixing and pulverized product in the pulverized coal combustion furnace, and the fine particles derived from the composition of the combustion coal fine particles (pulverized coal) and the mixed combustion combustion aid 1 in this combustion field. As a result, it is possible to improve the combustibility in the pulverized coal combustion furnace, which cannot be expected only by burning only the fine particles (pulverized coal) of the combustion coal, and to reduce NOx and SOx in the exhaust gas. In addition, the new mineralogical composition added with calcium carbonate at the time of co-firing in the pulverized coal combustion furnace (combustion temperature 1450 ° C.) can improve the properties and particle size composition of the combustion ash (fly ash), and the above mineralogical composition. Pozzolanic reactivity to high-temperature combustion ash (fly ash) can be promoted. As shown in FIG. 3, the pulverized coal combustion furnace 40 is a furnace in which a pulverized coal fuel (mixed and finely pulverized product) 41 is supplied into the combustion cylinder 42 together with air and burned by the burner 43. Primary air heated by a preheater (not shown) is supplied from the upper end of the combustion cylinder 42 together with pulverized coal fuel (mixed and finely pulverized product) 41, and secondary air heated by the preheater 44 is combusted cylinder 42. The two-stage combustion air supplied to the upper part of the combustion chamber and further heated by the preheater 46 is supplied to the upper part and the central part of the combustion cylinder 42. Accordingly, the pulverized coal fuel (mixed and finely pulverized product) 41 is configured to burn at a relatively high temperature. Reference numeral 47 in FIG. 3 is a hopper for storing pulverized coal fuel (mixed and finely pulverized product) 41, and reference numeral 48 is a cyclone. Further, reference numeral 49 in FIG. 3 is a bag filter, and reference numeral 51 is a plurality of carrier air introduction ports.

[4] Combustion method for mixed and finely pulverized mixture of co-firing combustion aid 2 and combustion coal (Fig. 1)
By mixing the coal for combustion with an average particle size of 50 mm or less and the combustion aid 2 for mixed combustion so that the amount of the combustion aid for mixed combustion becomes 3 to 25 mass% with respect to 100 mass% of the coal for combustion. A mixture is prepared, and this mixture is pulverized to prepare a mixed and pulverized product. Then, the mixed and finely pulverized product is supplied to the pulverized coal combustion furnace and burned. Thereby, in addition to the effect by the combustion method of said [3], the effect by the combustion method of said [2] is acquired.

Examples of the present invention are shown below together with comparative examples. The present invention is not limited to these examples.

  First, Table 1 shows the component composition of paper sludge by paper mill used in Examples and Comparative Examples, and Table 2 shows the type of coal and the component composition and properties after drying. In Table 1, PS is paper sludge.

In Table 1, “moisture content before drying (%)” refers to the moisture content of the paper sludge when the slurry discharged from the papermaking process is compression-dehydrated. Further, “fiber after drying (mass%)” means that the above-mentioned compressed dehydrated product is dried at 105 ° C., and the dried product is heat-treated at 500 ° C. in an oxidizing atmosphere. , Lignin substance) is a value obtained by calculation. In addition, “calcium carbonate after drying (mass%)” is obtained by further heating at 500 ° C. and treating at 900 ° C. The weight loss at that time is regarded as CO ₂ decomposed from calcium carbonate (CaCO ₃ ). This is a value obtained by calculating the mass% of calcium carbonate from the atomic weight ratio of CaO and CO ₂ . Furthermore, “other inorganic substances (mass%)” is a value obtained by calculating the remainder of the above-mentioned fibrous substance and calcium carbonate as subtracted from the total composition of 100 mass%. In addition, as a mineral composition of “other minerals”, kaolinite was mainly identified by X-ray diffraction.

  In Table 2, “Australian Coal A” is a steam coal produced in Australia, has low volatile content, high combustion sulfur and nitrogen content, and has expansibility and weak cohesion. Belongs to coal. In contrast, “KCM Coal” produced by Kushiro Coalmine and “Australian Coal B” produced by Australia are both volatile and non-flammable, and therefore belong to easily burnable coal. "Is a coal with extremely low sulfur content and excellent combustion. The “industrial analysis” is an analytical value based on JIS standards, and the fuel ratio is a value measured by fixed carbon / volatile matter (dry ash free basis).

<Example 1>
First, two types of paper sludge (average particle size: 10 mm or less) shown in Table 1 and three types of coal powder (average particle size of 2 mm or less) shown in Table 2 were prepared. Next, the paper sludge and coal powder were blended so that the mass ratio (dry basis) was 1: 1. Next, the paper sludge was mixed while being mixed to prepare a mixture. Furthermore, the said mixture was shape | molded into the pellet form using the extrusion molding machine which has two or more pellet-shaped dice | dies with a diameter of 5 mm, and the pellet-form mixed molded product was obtained. This pellet-shaped mixed molded product was designated as Example 1.

<Comparative Examples 1 and 2>
Paper sludge (average particle size: 10 mm or less) discharged from the B paper mill was used as Comparative Example 1, and KCM charcoal (average particle size of 2 mm or less) of the above coal powder was used as Comparative Example 2.

<Test 1 and evaluation>
The drying characteristics of the pellet-shaped mixed molded product of Example 1, the paper sludge of Comparative Example 1, and the coal powder of Comparative Example 2 were measured. Specifically, first, one pellet-shaped mixed molded product of Example 1 (5 g), 5 g of paper sludge of Comparative Example 1 and 5 g of coal powder of Comparative Example 2 were prepared. Next, from the relationship between the moisture content (%) and the drying time when heated from room temperature to 105 ° C. with a dryness measuring device, the mixed molded product of Example 1, the paper sludge of Comparative Example 1, and the Comparative Example The moisture content of coal powder No. 2 was measured. The result is shown in FIG. FIG. 4 shows the average value of three data obtained by performing the above test three times.

  As is clear from FIG. 4, the mixed molded product of Example 1 was heated from room temperature, passed through constant rate drying with a moisture content of about 10%, and reduced to drying with a target moisture content of 8.0%. Showed almost the same drying rate as the paper sludge of Comparative Example 1. This means that the drying rate of the paper sludge is not affected by its compaction. Therefore, the drying characteristics of the mixed molded product of Example 1 are the points that bring about a significant reduction in the drying cost related to the effective use of paper sludge, especially the handling and equipment for the pre-treatment of raw materials for higher recycling. This is an extremely important finding. Further, the drying characteristics of the mixed molded product of Example 1 enable highly efficient thermal recycling of the fiber contained in the paper sludge as clean woody biomass energy by drying. In addition, although the pellet-shaped mixed molded product was used in Example 1, strictly speaking, the mixed molded product after drying, that is, the dried molded product (combustion aid for mixed firing) is used in Example 1.

<Example 2>
A mixture of Example 1 was formed into a stick shape by using an extrusion molding machine having a plurality of dies having a diameter of 5 mm to produce a pellet-shaped mixed molded product, and then the mixed molded product was placed on a vibrating conveyor. Then, the mixture is passed through a vibrating conveyor for a predetermined distance (2.0 m), and the pellet-shaped mixed molded product and a fragment of the mixed molded product partially broken are dried in an oven as they are to obtain a combustion aid for mixed firing. It was. This combustion aid for co-firing was designated as Example 2.

<Test 2 and evaluation>
Combustion aid for co-firing consisting of a stick-shaped dry molded product of Example 2 and a dried product (powdered product) of a fragment of the mixed molded product crushed on the vibration conveyor, with an opening of 2.0 mm, The particle size was measured after sieving with a vibrator having a size of 1.0 mm, 0.5 mm and 0.25 mm for 5 minutes with a vibrator. The results are shown in Table 3.

  As is apparent from Table 3, the powdered material having a size of 0.25 mm or less is extremely low at 1.0% or less, and has a strength that can withstand normal handling, storage, transportation, etc. In particular, the stick-like mixed firing of Example 2 Despite the fact that the combustion aid contains a large amount of woody biomass, it is excellent in moisture resistance and water resistance. Accordingly, it was found that the stick-shaped dry molded product of Example 2 has strength and the like when used as a combustion aid for coal-fired coal such as a fluidized bed or a stoker type as it is.

<Example 3>
The stick-shaped dry molded product of Example 2 was continuously compression-molded (linear pressure: 3 to 4 ton / cm) by a double roll type molding machine as it was without a binder, and a plate-like mixed combustion combustion aid was obtained. Obtained. This plate-like mixed combustion combustion aid was defined as Example 3. The internal volume of the plate-like cavity of the double roll type molding machine was about 1.0 cc.

<Example 4>
The stick-shaped dry molded product of Example 2 was continuously compression-molded (linear pressure: 3 to 4 ton / cm) with a double roll molding machine as it was without a binder, and an almond-shaped combustion aid for mixed firing was obtained. Obtained. This almond-like mixed combustion combustion aid was defined as Example 3. The internal volume of the almond-shaped cavity of the double roll type molding machine was about 6.0 cc.

<Test 3 and evaluation>
The crushing strengths of the combustion aids for mixed combustion of Examples 3 and 4 were measured. Specifically, 10 each of the combustion aids for mixed combustion of Examples 3 and 4 were prepared, a steel spherical indenter was pushed into the center of each surface, and the load when the tablet was broken was defined as the crushing strength. .

  As a result, the crushing strength of the plate-shaped mixed combustion combustion aid of Example 3 was 40 to 50 kg, and the crushing strength of the almond-shaped mixed combustion combustion aid of Example 4 was 100 to 120 kg. Accordingly, it has been found that the plate-like mixed combustion combustion aid and the almond-like mixed combustion aid have sufficient strength to withstand storage, handling and transportation for practical use.

<Example 4>
First, the paper sludge (average particle size: 10 mm or less) discharged from the A paper mill in Table 1 and the KCM charcoal (average particle size of 2 mm or less) in Table 2 have a mass ratio (dry basis) of 1: 1. It mix | blended so that it might become, and it mixed, dissolving the said paper sludge, and prepared the mixture. Subsequently, the said mixture was shape | molded into the pellet form using the extrusion molding machine which has two or more pellet-shaped dice | dies with a diameter of 5 mm, and the pellet-form mixed molded object was produced. Next, the mixed molded product was dried in an oven so that the water content was 7 to 8% to prepare a dried molded product, and then compression molded (linear pressure: 3 to 4 ton / s) by a double roll type high pressure molding machine. cm) to obtain a combustion aid for co-firing consisting of a plate-like compression molded product. This combustion aid for co-firing was mixed with Australian coal A (average particle size of 5 mm or less) in Table 2 so that the mass ratio was 1: 9. This mixed fuel was designated as Example 4.

<Example 5>
First, the paper sludge (average particle size: 10 mm or less) discharged from the A paper mill in Table 1 and Australian charcoal B (average particle size of 2 mm or less) in Table 2 have a mass ratio (dry basis) of 1: 1. A combustion aid for co-firing consisting of a plate-like compression-molded product was obtained in the same manner as in Example 4 except that it was blended so as to be. This combustion aid for co-firing was mixed with Australian coal A (average particle size of 5 mm or less)% in Table 2 at a mass ratio of 1: 9. This mixed fuel was designated as Example 5.

<Example 6>
First, the paper sludge (average particle size: 10 mm or less) discharged from the paper mill A in Table 1 and the Australian coal A (average particle size 2 mm or less) in Table 2 have a mass ratio (dry basis) of 1: 1. A combustion aid for co-firing consisting of a plate-like compression-molded product was obtained in the same manner as in Example 4 except that it was blended so as to be. This combustion aid for co-firing was mixed with Australian coal A (average particle size of 5 mm or less)% in Table 2 at a mass ratio of 1: 9. This mixed fuel was designated as Example 6.

<Comparative Example 3>
Without mixing the combustion aid for mixed combustion, only the Australian coal A powder shown in Table 2 (average particle size of 5 mm or less) was used as the fuel. This single fuel was designated as Comparative Example 3.

<Test 4 and evaluation>
Combustion tests were performed on the mixed fuels of Examples 4 to 6 and the single fuel of Comparative Example 3. In the combustion test, in the circulating fluidized bed coal combustion furnace 10 shown in FIG. 2, the fixed point temperature is maintained in the range of 850 to 860 ° C., and the oxygen concentration in the exhaust gas is maintained in the range of 3 to 4%. The fuel 16 was circulated through the combustion furnace main body 13, the primary cyclone 11 and the loop seal 14 together with the fluidizer (fine alumina) 17, and the amount of coal supplied per hour was measured in a state where stable combustion could be maintained. The results are shown in Table 4. The oxygen concentration in the exhaust gas is extracted from the exhaust pipe between the gas cooler 18 into which the exhaust gas discharged from the secondary cyclone 12 flows and the bag filter 19 into which the exhaust gas that has passed through the gas cooler 18 flows. Analyzed by analyzer. Moreover, PS in Table 4 is paper sludge.

  As is clear from Table 4, in the single fuel of Comparative Example 3 in which only the combustion coal is used without mixing the combustion aid (0%) with the combustion coal, the fuel required for maintaining the same combustion is supplied. In the mixed fuels of Examples 4 to 6 in which the coal quantity was 4.8 kg / hour, while the combustion aid for mixed combustion (10%) was mixed with combustion coal, fuel supply required for maintaining the same combustion The amount was greatly reduced to 2.55 to 2.78 kg / hour. This is not related to the amount of heat generated from each fuel, and does not mean direct energy saving. The mixed fuels of Examples 4 to 6 match the combustion mechanism of a circulating fluidized bed coal combustion furnace. It is considered that the combustion characteristics obtained were brought about by mixing the combustion aid for co-firing with paper sludge as the raw material and coal for combusting, and the co-firing method.

<Test 5 and evaluation>
Similarly to the test 4, the combustion test was performed on the mixed fuels of Examples 4 to 6 and the single fuel of Comparative Example 3. In the combustion test, in the circulating fluidized bed coal combustion furnace 10 shown in FIG. 2, the fixed point temperature is maintained in the range of 850 to 860 ° C., and the oxygen concentration in the exhaust gas is maintained in the range of 3 to 4%. The fuel 16 is circulated through the combustion furnace main body 13, the primary cyclone 11 and the loop seal 14 together with the fluidizer (fine alumina) 17, and SOx in the exhaust gas discharged outside the circulating combustion system of the circulating fluidized bed coal combustion furnace 10. Concentration and NOx concentration were measured. Specifically, the SOx concentration and NOx concentration in the exhaust gas discharged from the primary cyclone 11 and passed through the secondary cyclone 12, the gas cooler 18, and the bag filter 19 were measured. The results are shown in FIGS. The oxygen concentration in the exhaust gas was extracted and analyzed from the exhaust pipe between the gas cooler 18 into which the exhaust gas discharged from the secondary cyclone 12 flows and the bag filter 19 into which the exhaust gas that passed through the gas cooler 18 flows. . Moreover, PS in Table 4 is paper sludge.

Combustion coal was not mixed with combustion aid (0%) for combustion, only combustion coal was used, and Australian coal A with a high combustible sulfur content of 0.48 mass% (dry ash free) was used. In Comparative Example 3, the SO ₂ concentration in the exhaust gas was as high as 370 ppm by volume. As is clear from FIG. 5, even when Australian coal A having a high combustible sulfur content of 0.48 mass% (dry ash free) was used, the combustion coal for combustion (10%) was mixed with the combustion coal. In Examples 4 to 6, the SO ₂ concentration in the exhaust gas decreased, and the desulfurization rate was improved to 55 to 69% when the desulfurization rate of Comparative Example 3 was taken as the standard (0%). At this time, the Ca / S value of the ratio of sulfur to calcium in the fuel was as small as 0.2 in Comparative Example 3, whereas it was as large as 1.6 to 2.2 in Examples 4 to 6. . Such a desulfurization effect is considered to be achieved by the fact that SO ₂ in the exhaust gas is fine in the combustion aid for mixed combustion, and reaction and fixation with highly reactive synthetic calcium carbonate, that is, paper sludge. It is thought that this was brought about by co-firing the combustion aid for co-firing with the coal for fuel utilizing the raw material composition.

  On the other hand, as is clear from FIG. 6, in Comparative Example 3 in which only the combustion coal was used without mixing the combustion aid (0%) with the combustion coal, the NOx concentration in the exhaust gas was 170 ppm (oxygen) 6% conversion: 140 to 160 ppm), whereas in Examples 4 to 6 in which the combustion coal for combustion (10%) was mixed with the combustion coal, the NOx concentration in the exhaust gas was 170 to 220 ppm (oxygen concentration) 6% conversion: 160 to 200 ppm), which is slightly higher than Comparative Example 3. In this manner, the NOx concentration in the exhaust gas was slightly increased in Comparative Examples 3 to 6 in Examples 4 to 6 due to the improvement in combustibility by co-combustion of the combustion aid and combustion coal, but the concentration was regulated by the amount of exhaust gas. Among industrial boilers we received, the concentration was sufficient to clear the emission scale of small and medium boilers that require denitration measures.

<Test 6 and evaluation>
Similarly to the test 4, the combustion test was performed on the mixed fuels of Examples 4 to 6 and the single fuel of Comparative Example 3. In the combustion test, in the circulating fluidized bed coal combustion furnace 10 shown in FIG. 2, the fixed point temperature is maintained in the range of 850 to 860 ° C., and the oxygen concentration in the exhaust gas is maintained in the range of 3 to 4%. The fuel 16 is circulated through the combustion furnace main body 13, the primary cyclone 11 and the loop 14 together with the fluidizer (fine alumina) 17, and the cyclone ash and bugs discharged out of the circulating combustion system of the circulating fluidized bed coal combustion furnace 10. The ash was collected by the secondary cyclone 12 and the bag filter 19 respectively, and the collected amounts of the cyclone ash and the bag ash were measured to calculate the collection ratios. The results are shown in Table 5. The oxygen concentration in the exhaust gas was extracted and analyzed from the exhaust pipe between the gas cooler 18 into which the exhaust gas discharged from the secondary cyclone 12 flows and the bag filter 19 into which the exhaust gas that passed through the gas cooler 18 flows. . Bag ash is a fine particle classified by a secondary cyclone from combustion ash with a particle size of 10 to 20 μm as a cut point. Furthermore, PS in Table 4 is paper sludge.

  As is apparent from Table 5, in Comparative Example 3 in which only the combustion coal was used without mixing the combustion coal (0%) with the combustion coal, the mass ratio of bag ash: cyclone ash was 34. 8 to 65.2, but in Examples 4 to 6 in which combustion coal was mixed with combustion coal (10%), the mass ratio of bug ash: cyclone ash was (15.5 to 32). 7): (86.0 to 67.3), and in Examples 4 to 6, the distribution tendency increased to the cyclone ash. In particular, in Examples 4 and 6 in which KCM coal and Australian coal A are used as raw materials for combustion aids for mixed combustion, 80% or more of them are recovered as cyclone ash, and Examples in which Australian coal A is used as raw materials for combustion aids for mixed combustion In No. 6, nearly 80% was recovered as cyclone ash.

<Test 7 and evaluation>
The particle size distributions of bag ash obtained by burning the mixed fuels of Examples 4 and 6 recovered in Test 6 and bag ash obtained by burning the single fuel of Comparative Example 3 were measured. The results are shown in FIGS. 7 (a) and 8 (a). Moreover, the particle density (g / cm < ³ >) of the bag ash in a circulating fluidized bed coal combustion furnace was measured. The results are shown in Table 6.

  As is clear from FIGS. 7 (a) and 8 (a), bag ash is easily burned as coal powder in the combustion aid for mixed combustion, regardless of the type and quality of coal used in the combustion aid for mixed combustion. In the case of mixed combustion of the mixed fuel of Example 4 using the natural KCM charcoal (fuel ratio: 0.98) and Example 6 using the non-combustible Australian coal A (fuel ratio 1.74) Compared with the combustion of single fuel of Comparative Example 3 in which only Australian coal A was used as combustion coal without using combustion aids, the mode diameter (maximum frequency%) increased with that value and the same as the median diameter. The particle size distribution shifted to the correct value. Thus, in Examples 4 and 6, the mode diameter of the bag ash was shifted to the fine particle side, and the particle size distribution range was narrow, and the particle size constitution of finely stable powder was exhibited.

  In Table 6, the particle densities of the bag ash of Examples 4 to 6 in which the combustion aid for mixed combustion is mixed with the combustion coal are all used only for the combustion coal without mixing the mixed combustion combustion agent with the combustion coal. Compared with the particle density of the bag ash of Comparative Example 3, the difference was larger, but a significant difference in the particle density value confirmed the transition of the mode diameter to the fine particle side in the particle size distribution of the bag ash. ing.

<Test 8 and evaluation>
The particle size distributions of the cyclone ash by combustion of the mixed fuel of Examples 4 and 6 recovered in Test 6 and the cyclone ash by combustion of the single fuel of Comparative Example 3 were measured, respectively. The results are shown in FIGS. 7 (b) and 8 (b). Moreover, the particle diameter of the cyclone ash of Examples 4-6 collect | recovered in the test 6 and the cyclone ash of the comparative example 3, the shape, the aggregate | assembly condition of a particle, etc. were observed with the microscope. The result is shown in FIG.

  As apparent from FIGS. 7B and 8B, the particle size distribution of the cyclone ash of Examples 4 to 6 in which the combustion aid for mixed combustion is mixed with the combustion coal has a wide particle size distribution range. Moreover, compared with the particle size distribution of the cyclone ash of Comparative Example 3 in which only the combustion coal is used without mixing the combustion agent for combustion with the combustion coal, both the median diameter and the mode diameter are increased. While decreasing the frequency%, a characteristic particle size distribution that increases the frequency of the coarse particle size was exhibited. Thus, the cyclone ash of Examples 4 and 6 had a particle size distribution that was coarser as a whole than the cyclone ash of Comparative Example 3.

  As is clear from FIG. 9, the cyclone ash of Comparative Example 3 was observed as an aggregate of particles over a wide particle size range with unclear grain boundaries (FIG. 9 (a)). On the other hand, in the cyclone ash of Examples 4 to 6, as in Comparative Example 3, although the particle size distribution was wide, the entire particles were observed as aggregates with clearer grain boundaries (FIG. 9 ( b) to (d)). This is because in Examples 4 to 6, the cyclone ash particles are slightly sintered during the combustion, and are not found in the combustion ash of a normal circulating fluidized bed coal combustion furnace, due to the welding between the ash particles. It also suggested partial coarsening, and the important findings were obtained as an effect of improving the particle size composition brought about by the raw material composition of the paper sludge in the combustion aid for mixed combustion. In addition, the combustion temperature is relatively low at 850 ° C., and the combustion ash is recovered outside the circulating fluidized bed coal combustion furnace in two stages, a secondary cyclone and a bag filter dust collector. Morphological changes such as coal-containing minerals, kaolinite illite clay minerals, etc. (other minerals generated by changes in crystal structure: mullite, amorphous quartz, aluminosilicates, etc.) Etc.) was not generated. In fact, in any ash, the formation of meta-kaolinite from kaolinite could be confirmed by X-ray diffraction analysis, but the formation of mullite or the like by sintering / melting was not observed.

<Test 9 and evaluation>
Water and cement were poor in the cyclone ash and bag ash obtained by burning the mixed fuels of Examples 4 to 6 and the cyclone ash and bag ash obtained by burning the single fuel of Comparative Example 3 collected in Test 6, respectively. The cured body was prepared by blending, and the crushing strength of the cured body was measured. Here, for the cyclone ash, the test sample of the above cured body was changed to a mass ratio of 100% combustion ash and 30% water, and the cement mixing ratio was changed to 0%, 5% and 10%. After mixing and mixing, extrusion molding (low pressure molding) was carried out to produce a cured product having a diameter, thickness and mass of 25 mm, about 2 mm and 3 g, respectively. In addition, for the bag ash, the test sample of the above-mentioned cured body was mixed by mixing 30% water and 5% cement with 100% combustion ash by mass ratio, and extrusion molding (low pressure molding). A cured body having a diameter, thickness and mass of 25 mm, approximately 2 mm and 3 g was produced. And the measurement of crushing strength was performed by the indentation method of the steel spherical indenter, after leaving a hardening body still for one week. Specifically, a steel spherical indenter having a diameter of 10 mm was pressed against the upper surface of the cured body to gradually increase the load, and the load when the cured body was broken was defined as the crushing strength. The result is shown in FIG. In addition, the said crushing strength was performed 5 times for every combustion ash (cyclone ash and bug ash) and every mixing ratio of cement, and those average values were calculated. On the other hand, the content ratios of SiO ₂ , Al ₂ O ₃ and CaO in the cyclone ash and the bag ash were analyzed, respectively. The results are shown in Table 7. In Table 7, PS is paper sludge.

  As is clear from FIG. 10, for the cyclone ash, when no cement was blended, the crushing strength of the cured body using the cyclone ash by the combustion of the mixed fuel of Examples 4 to 6 was the same as that of Comparative Example 3. It was almost the same as the crushing strength of the hardened body using cyclone ash by combustion of one fuel. However, when cement was poorly blended (cement blending: 5%), the crushing strength of the cured body using cyclone ash by combustion of a single fuel in Comparative Example 3 was as low as 0.6 kg, whereas Example 4 The crushing strength of the cured body using cyclone ash by combustion of the mixed fuel of -6 increased to 1.5-4.1 kg. In addition, when the cement was poorly blended (cement blending: 10%), the crushing strength of the cured body using cyclone ash by combustion of the single fuel of Comparative Example 3 was as low as 2.4 kg, whereas Example 4 The crushing strength of the cured product using cyclone ash by combustion of the mixed fuel of -6 increased to 4.8-11.2 kg. The reason for this is that in the cyclone ash produced by combustion of the mixed fuels of Examples 4 to 6, the pozzolanic reactivity is imparted by the grain boundary sintering, and as shown in Table 7, the calcium carbonate in the combustion aid for mixed combustion is used. It is thought that the strength of the hardened body containing poor cement was increased by the improvement of the properties of the combustion ash, such as the improvement of the particle size composition, in addition to the high content of quick lime, in addition to the high content of quicklime. It is done.

  On the other hand, for the bag ash, when the cement was poorly blended (cement blend: 5%), the crushing strength of the cured body using the bag ash from the combustion of a single fuel in Comparative Example 3 was as low as 1.2 kg. On the other hand, the crushing strength of the cured body using bag ash by the combustion of the mixed fuels of Examples 4 to 6 increased to 2.2 to 3.2 kg. As the reason, among the reasons relating to the cured body using cyclone ash, it is considered that bug ash which is a fine particle is particularly affected by mild sintering of the ash grain boundary and improvement of the particle size composition.

<Test 10 and evaluation>
The elution trace metal components in the cyclone ash and bag ash obtained by burning the mixed fuels of Examples 4 and 6 recovered in Test 6 and the cyclone ash and bag ash obtained by burning the single fuel of Comparative Example 3 were analyzed. The results are shown in Table 8. Here, the above-mentioned elution trace metal components are 5 elements (arsenic (As), selenium (Se), hexavalent chromium (Cr ⁶⁺ )) of elution tests generally examined in the treatment and utilization of coal combustion ash. , Boron (B) and fluorine (F)). These elements are easy to volatilize in the combustion process, so that Cr ⁶⁺ of group 1 (non-volatile element), As, B and Se of group 2 (volatile-condensable element), and group 3 (volatile) -Non-condensable) and F. In Table 8, PS is paper sludge.

As is apparent from Table 8, when the behavior of each element during combustion is considered, F (fluorine), which is a volatile / non-condensable element, is not captured by cyclone ash in Comparative Example 3 and most of it is captured. In contrast to concentration and adhesion to bag ash, in Examples 4 to 6, they were captured and immobilized by cyclone ash and bag ash. In particular, it was found that in Example 4 in which KCM coal was used as the coal powder for the combustion aid for mixed combustion, elution of F (fluorine) was suppressed. In addition, the non-volatile element Cr ⁶⁺ (hexavalent chromium) that is not found in the cyclone ash and the bag ash of Comparative Example 3 was used in Example 5 in which Australian Coal B was used as the coal powder for the combustion aid for mixed combustion. In Example 6 in which Australian coal A was used as the coal powder for the co-firing combustion aid, new concentration above the soil environment standard value in cyclone ash and bag ash was confirmed. This is presumed to be the result of the promotion of the oxidation of coal-derived Cr (chromium) by the Ca (calcium) content derived from the combustion aid for mixed combustion. The behavior of trace elements during the generation of such combustion ash is evidence of the interaction between each substance in the combined combustion field formed by the co-firing of flame-retardant combustion coal and co-firing combustion aid. It can be seen that this was brought about by the production of the composite combustion aid (fuel aid for co-firing) of the present technology and the new combustion mechanism (composite combustion field) by the co-firing method.

<Example 7>
First, the paper sludge (average particle diameter: 10 mm or less) discharged from the B paper mill in Table 1 and the KCM charcoal (average particle diameter of 2 mm or less) in Table 2 have a mass ratio (dry basis) of 1: 1. It mix | blended so that it might become, and it mixed, dissolving the said paper sludge, and prepared the mixture. Subsequently, the said mixture was shape | molded into the pellet form using the extrusion molding machine which has two or more dice | dies with a diameter of 5 mm, and the pellet-form mixed molded object was produced. Next, the mixed molded product was dried in an oven so that the water content was 7 to 8% to prepare a dried molded product, and then compression molded (linear pressure: 3 to 4 ton / s) by a double roll type high pressure molding machine. cm) to produce a plate-like compression molded product. Then, this plate-like compression molded product was pulverized to obtain a combustion aid for mixed firing having a particle size of 5 mm or less. Furthermore, after mixing this combustion aid for mixed combustion with Australian coal A adjusted to a particle size of 5 mm or less at a mass ratio of 1:10, 80% of powder having a particle size of 75 μm passes through this mixture. The finely pulverized mixed fuel was adjusted so that the top size was 150 μm and the average particle size (Dp50) was about 40 μm. This finely pulverized mixed fuel was designated as Example 7.

<Example 8>
First, the paper sludge (average particle size: 10 mm or less) discharged from the B paper mill in Table 1 and Australian charcoal B (average particle size of 2 mm or less) in Table 2 have a mass ratio (dry basis) of 1: 1. A combustion aid for co-firing consisting of a compression-molded product was obtained in the same manner as in Example 7, except that it was blended so that After mixing this combustion aid for co-firing with Australian coal A adjusted to a particle size of 5 mm or less in a mass ratio of 1:10, 80% of powder with a particle size of 75 μm passes through the top size. The finely pulverized mixed fuel was adjusted so that the average particle size (Dp50) was about 40 μm. This finely pulverized mixed fuel was designated as Example 8.

<Comparative example 4>
In Australian coal A adjusted to a particle size of 5 mm or less without mixing the combustion aid for mixed firing, 80% of the powder with a particle size of 75 μm passes, the top size becomes 150 μm, and the average particle size (Dp50) is about 40 μm. The finely pulverized single fuel was adjusted so that This finely pulverized single fuel was designated as Comparative Example 4.

<Test 11 and evaluation>
The finely pulverized mixed fuel of Examples 7 and 8 and the finely pulverized single fuel of Comparative Example 4 were supplied to a small pulverized coal combustion furnace 40 shown in FIG. Specifically, the fuel 41 is supplied while keeping the furnace heat input constant (burner vicinity temperature: 1400 ° C.) while swirling the burner 43, and under any operating condition, A combustion test was conducted with the oxygen concentration maintained at 4.2%. Then, the coal feed rate during combustion of the fuel 41 was calculated, the unburned content in the ash after combustion was measured, and the combustion efficiency was calculated from this unburned content. The results are shown in Table 9. In addition, the unburned part in ash is a measured value when pulverized coal combustion conditions are 79.3% for primary and secondary air and 20.7% for two-stage combustion air. Further, FIG. 11 shows the relationship between the NOx generation amount (ppm) and the unburned carbon ratio (%) when two-stage combustion is performed.

  As is clear from Table 9, the coal feed rate in the combustion of the finely pulverized single fuel of Comparative Example 4 was 5.85 kg / hour, whereas in the combustion of the finely pulverized mixed fuel of Examples 7 and 8 The coal feed rate increased slightly to 6.05 kg / hour and 6.00 kg / hour, respectively. However, in Examples 7 and 8, it was found that the combustibility could be improved from the unburned content and the combustion efficiency calculated therefrom. Therefore, in Examples 7 and 8, considering that about 5% of non-fuel paper sludge is contained in the finely pulverized mixed fuel, one of the effects of the mixed combustion is expected to reduce the use amount of combustion coal. it can. In Examples 7 and 8, 44% by mass of the wood sludge of paper sludge discharged from the B paper mill and 29% of the wood sludge of paper sludge discharged from the A paper mill on a dry basis. There are many, and thermal recycling with the increased amount can be expected.

  As is apparent from FIG. 11, the finely pulverized mixed fuel of Examples 7 and 8 and the finely pulverized single fuel of Comparative Example 4 are two of the air amounts required for combustion (oxygen concentration in exhaust gas: 4.2%). Although the proportion of the stage combustion air amount increased and NOx decreased, the unburned carbon ratio from the unburned ash content in the measured value increased. In such a tendency, the finely pulverized mixed fuels of Examples 7 and 8 were compared with the finely pulverized single fuel of Comparative Example 4 and the NOx was about 2% within the range where the unburned carbon ratio was 2% or less. It was found to reduce by 100 ppm. Moreover, as a practical numerical value in the combustion of the incombustible combustion coal, when the unburned carbon ratio is 1.0%, the combustion aid for mixed combustion of Examples 7 and 8 is mixed with the combustion coal and mixed combustion. In order to reduce the NOx concentration to about 250 ppm when only the combustion coal of Comparative Example 4 is burned, while the NOx concentration is about 250 ppm, the unburned carbon ratio is reduced to 2.0%. It is necessary to strengthen combustion. This difference in the unburned carbon ratio of 1% has a great effect on the reduction of coal consumption and the properties and quality of the use of combustion ash. In other words, the co-firing combustion aids of Examples 7 and 8 in which paper sludge and coal powder were uniformly mixed in advance and formed at high pressure were mixed with pulverized coal in advance with the flame-retardant combustion coal. As a result of being supplied to the combustion furnace in a state of being uniformly dispersed therein, the pulverized coal particles, the single separated particles of the raw material derived from the composition of the combustion aid, and the interaction between the composite particles and the "composite combustion field" It is thought to be deeply related to formation. Therefore, it is difficult to form such a combustion field by co-firing paper sludge with mere non-combustible combustion coal, which has a great technical difficulty in processing such as drying and pulverization. It is thought that the co-firing together with the improvement of ignitability and flammability, as well as the multifaceted effects related to the property improvement / reformation in the use of combustion ash.

<Test 12 and evaluation>
The finely pulverized mixed fuels of Examples 7 and 8 and the finely pulverized single fuel of Comparative Example 4 are supplied to the small pulverized coal combustion furnace 40 shown in FIG. The SO ₂ concentration in the obtained exhaust gas was measured, and the SO ₂ conversion rate obtained from the SO ₂ concentration and the theoretical SO ₂ concentration in the exhaust gas was calculated. The results are shown in Table 10.

As is clear from Table 10, in Examples 7 and 8 and Comparative Example 4, the desulfurization rate from the SO ₂ conversion rate is 6.8 to 15.2%, which is compared with the high desulfurization rate in the circulating fluidized bed coal combustion furnace. Thus, the effect of co-firing with the combustion coal of the co-firing combustion aid was not clearly confirmed. This is because the calcium carbonate-derived CaO particles in the paper sludge contained in the combustion aid raw material for mixed combustion that brings about the desulfurization action sinters by passing through the high temperature part (around 1400 ° C.) in the turbulent flow furnace. This is thought to be due to a decrease in sex.

<Test 13 and evaluation>
The particle size distributions of the combustion ash obtained by combustion of the finely pulverized mixed fuel of Example 7 recovered in Test 11 and the combustion ash obtained by combustion of the finely pulverized single fuel of Comparative Example 4 were measured. The result is shown in FIG.

  As is clear from FIG. 12, the particle size constitution of the combustion ash obtained by burning the finely pulverized single fuel of Comparative Example 4 using only the combustion coal without using the combustion aid for mixed combustion is the combustion for mixed combustion. It was found that this was improved by the co-firing of the finely pulverized mixed fuel of Example 7 in which the auxiliary agent was mixed with combustion coal. That is, in the combustion ash by the mixed combustion of Example 7, the combustion ash by the mixed combustion of Example 7 is on the coarse grain side while increasing the frequency with a mode diameter of about 15 μm as in the combustion ash by the combustion of Comparative Example 4. It exhibited a particle size distribution in which particles between 40 and 160 μm decreased. This is because the non-combustible Australian coal A has low volatility and also has expansibility and weak cohesion, so that the combustion ash produced by co-firing in Example 7 enters the coarse grain side during the high-temperature combustion process. It is considered that the porous char (unburned carbon) and the vitreous molten multi-foamed particles that are coming in are mixed with the combustion aid co-firing to suppress the formation of the coarse particle char, and the foamed coarse particles break up and shift to the fine particle side. If the improvement of the particle size composition and the combustibility are deeply related, as shown in Table 9 in Test 11, the combustion by combustion of Comparative Example 4 is a comparison of the unburned content in the combustion ash of pulverized coal. However, it is considered to be supported by the fact that it decreased to 4.5% in the combustion by the mixed combustion of Example 7 while it was as large as 9.4%.

<Test 14 and evaluation>
Cured ash obtained by burning the finely pulverized mixed fuel of Examples 7 and 8 recovered in Test 11 and the burned ash of the combusted ash of the finely pulverized single fuel of Comparative Example 4 by blending poorly with water and cement, respectively. Was prepared, and the crushing strength of the cured body was measured. Here, the test sample of the cured body was mixed by mixing 30% water and 5% cement with 100% combustion ash in a mass ratio, and extrusion molding (low pressure molding). Cured bodies having a mass of 25 mm, approximately 2 mm, and 3 g, respectively, were prepared. And the measurement of crushing strength was performed by the indentation method of the steel spherical indenter, after leaving a hardening body still for one week. Specifically, a steel spherical indenter having a diameter of 10 mm was pressed against the upper surface of the cured body to gradually increase the load, and the load when the cured body was broken was defined as the crushing strength. The result is shown in FIG. In addition, the said crushing strength was performed 5 times for every combustion ash, and those average values were computed. On the other hand, the content ratio of SiO ₂ , Al ₂ O ₃ and CaO in the combustion ash was analyzed. The results are shown in Table 11. In Table 11, PS is paper sludge.

As is clear from FIG. 13, when the cement was poorly blended (cement blending: 5%), the crushing strength of the cured body using the combustion ash from the combustion of the single fuel of Comparative Example 4 was as low as 3.8 kg. On the other hand, the crushing strength of the hardened body using the combustion ash by the combustion of the mixed fuel of Examples 7 and 8 increased to 6.0 kg and 6.8 kg. Also, the pattern at the time of destruction was buckling failure in the cured body using the combustion ash from the combustion of a single fuel in Comparative Example 4, whereas the combustion ash from the combustion of the mixed fuel in Examples 7 and 8 was changed. The crushing of the cured body used was brittle fracture. This is the production of a novel sandy granulated product with water permeability and water retention by poor blending of slaked lime etc. to combustion ash by mixed firing of Examples 7 and 8 and carbonation treatment with a certain degree of interparticle bonding strength. Suggests possibilities. The curing characteristics of the combustion ash by the co-firing of Examples 7 and 8 described above are the improvement in the properties and particle size composition by the co-firing of the new combustion aid, and the main chemical composition of the co-fired ash as shown in Table 11. It is thought to be caused by a hydration hardening reaction of some pozzolanic reactive silica (SiO ₂ ), alumina (Al ₂ O ₃ ) and slaked lime (calcium hydroxide: Ca (OH) ₂ ) derived from a combustion aid.

<Test 15 and evaluation>
The elution trace metal component in the combustion ash by combustion of the finely pulverized mixed fuel of Examples 7 and 8 recovered in Test 11 and the combustion ash by combustion of the finely pulverized single fuel of Comparative Example 4 was analyzed. The results are shown in Table 12. Here, the above-mentioned elution trace metal components are 5 elements (arsenic (As), selenium (Se), hexavalent chromium (Cr ⁶⁺ )) of elution tests generally examined in the treatment and utilization of coal combustion ash. , Boron (B) and fluorine (F)). These elements are easy to volatilize in the combustion process, so that Cr ⁶⁺ of group 1 (non-volatile element), As, B and Se of group 2 (volatile-condensable element), and group 3 (volatile) -Non-condensable) and F. In Table 9, PS is paper sludge. Further, “<0.01” in Table 9 is a soil environment standard value, and the numerical value in parentheses is an actual measurement value.

As is clear from Table 12, in the combustion ash produced by combustion of finely pulverized single fuel of Comparative Example 4 using only combustion coal without using the co-firing combustion aid, the environmental soil standard value for all the above five elements. In the combustion ash produced by co-firing the finely pulverized mixed fuel of Examples 7 and 8 in which the co-firing combustion aid is mixed with the coal for combustion, both As (arsenic) and Se (selenium) are environmental soil standards. The F (fluorine) elution amount was lower than that of Comparative Example 4. This is thought to be due to the insoluble “Ca salt” formed by the reaction with CaO derived from the combustion aid for mixed combustion in Examples 7 and 8, for example, F (fluorine) becomes CaF ₂ and immobilized. In addition, the amount of elution of B (boron) did not change between Examples 7 and 8 and Comparative Example 4, whereas in Cr ⁶⁺ (hexavalent chromium), Examples 7 and 8 increased from Comparative Example 4. Although it was a result, it is thought that this is a result of promoting the oxidation of Cr (III) by CaO derived from the combustion aid for mixed combustion. From such behavior and elution characteristics of each element, all of the five elements cannot be reduced below the environmental soil standard value only by in-furnace treatment by co-firing of the combustion aids for co-firing in Examples 7 and 8. However, in the in-furnace treatment by the mixed combustion technology of the present invention, it can be linked to pretreatment for the final treatment use of combustion ash, so the current properties and quality variations have a certain range of properties. Therefore, the technical effect is large in stably supplying the fly ash of quality.

  The combustion aid for co-firing of the present invention meets the long-standing urgent and important needs in the field of high-grade recycling of paper sludge discharged in large quantities from many paper mills nationwide and environmentally friendly and energy-saving coal applications. To do. For this reason, it contributes greatly in a wide industrial field such as paper industry, various industries having coal-fired power plants, and electric power industry. Plate-shaped or almond-shaped high-pressure molded products that can be produced in the same way as the combustion aids for mixed firing are fluidized bed furnaces, circulating fluidized bed coal combustion furnaces, moving bed (stoker) type coal combustion furnaces, and large and medium-sized incinerations. It can be used in furnaces, gasification combustion furnaces, and pulverized coal combustion furnaces, and contributes greatly to energy saving and environmental measures.

10 Circulating Fluidized Bed Coal Combustion Furnace 16 Fuel (mixture of combustion coal and co-firing combustion aid)
40 Pulverized coal combustion furnace 41 Pulverized coal fuel (mixed and finely pulverized product of combustion coal and co-firing combustion aid)

Claims (5)

A method for producing a combustion aid for co-firing to mix with combustion coal and assist combustion of the combustion coal,
A mixture of paper sludge crushed and dehydrated and then pulverized and coal powder is extruded into a rod shape of a predetermined length, and then the molded product is cut and dried to have a moisture content of 7 to 10%. A method for producing a combustion aid for co-firing, characterized in that a stick-shaped dry molded article is produced, and the dry molded article is further compression-molded at a predetermined pressure without a binder to form a plate or almond . Combustion coal having an average particle size of 50 mm or less and a combustion aid for mixed combustion produced by the method according to claim 1, wherein 3 to 25 mass of the combustion aid for mixed combustion is used with respect to 100 mass% of the combustion coal. A step of preparing a mixture by mixing in a ratio of%,
A method of burning coal for combustion, comprising a step of supplying the mixture to a fluidized bed furnace, a circulating fluidized bed coal combustion furnace, a moving bed coal combustion furnace, an incinerator or a gasification combustion furnace and burning the mixture. Combustion coal having an average particle size of 50 mm or less and a combustion aid for mixed combustion produced by the method according to claim 1 , wherein 3 to 25 mass of the combustion aid for mixed combustion is used with respect to 100 mass% of the combustion coal. A step of preparing a mixture by mixing in a ratio of%,
A method of burning coal for combustion, comprising a step of supplying the mixture to a fluidized bed furnace, a circulating fluidized bed coal combustion furnace, a moving bed coal combustion furnace, an incinerator or a gasification combustion furnace and burning the mixture. Combustion coal having an average particle size of 50 mm or less and a combustion aid for mixed combustion produced by the method according to claim 1, wherein 3 to 25 mass of the combustion aid for mixed combustion is used with respect to 100 mass% of the combustion coal. A step of preparing a mixture by mixing in a ratio of%,
A step of preparing a mixed and pulverized product by pulverizing the mixture;
A method for combusting coal for combustion, comprising a step of supplying the combusted and pulverized product to a pulverized coal combustion furnace and combusting it. Combustion coal having an average particle size of 50 mm or less and a combustion aid for mixed combustion produced by the method according to claim 1 , wherein 3 to 25 mass of the combustion aid for mixed combustion is used with respect to 100 mass% of the combustion coal. A step of preparing a mixture by mixing in a ratio of%,
A step of preparing a mixed and pulverized product by pulverizing the mixture;
A method for combusting coal for combustion, comprising a step of supplying the combusted and pulverized product to a pulverized coal combustion furnace and combusting it.