Method for manufacturing sintered body

Abstract

To provide a method for manufacturing an environmentally friendly sintered body.SOLUTION: A method for manufacturing a sintered body according to the present disclosure is a method for manufacturing a sintered body that is obtained by sintering limestone. The method includes loading the limestone and loading solid biomass fuel into the inside of a firing furnace, followed by sintering of the limestone.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] The present disclosure relates to a method for producing a sintered body. [Background technology]

[0002] Conventionally, environmentally friendly calcination technologies have been developed for calcining limestone, such as by using fuels that can replace fossil fuels such as petroleum and coal, and by suppressing emissions of carbon dioxide and other substances generated by fuel combustion. For example, Patent Document 1 discloses a method for producing quicklime and burnt dolomite, which includes a step of gasifying organic matter such as waste plastics in a gas generating unit to generate combustible gas, and a step of feeding the combustible gas generated in the above step into a calcining furnace to generate quicklime and burnt dolomite. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-072446 Summary of the Invention [Problem to be solved by the invention]

[0004] There is a need to develop environmentally friendly firing technology that appropriately employs fuels that can replace fossil fuels in relation to the firing technology of Patent Document 1. Furthermore, Patent Document 1 requires that the fuel be gasified once in the gas generating section, and there is a need for more efficient firing of fuel.

[0005] Therefore, an object of the present disclosure is to provide an environmentally friendly method for producing a sintered body, and also to provide an efficient method for producing a sintered body. [Means for solving the problem]

[0006] The method for producing a calcined body according to the present disclosure is a method for producing a calcined body obtained by calcining limestone, in which the limestone is loaded into a calcination furnace, and solid biomass fuel is loaded to calcinate the limestone. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to provide an environmentally friendly method for producing a sintered body, and also to provide an efficient method for producing a sintered body. [Brief explanation of the drawings]

[0008] [Figure 1A] Graph showing the temperature of each combustion chamber versus firing time [Figure 1B] Graph showing the heat load of each combustion chamber versus firing time [Figure 2] Graph showing flame temperatures when using various fuels [Figure 3A] Graph showing residual carbon dioxide in fired bodies obtained using each fuel [Figure 3B] Graph showing silicon dioxide in the fired body obtained using each fuel DETAILED DESCRIPTION OF THE INVENTION

[0009] <Embodiment> The embodiments of the present disclosure will be described in detail. Note that the manufacturing method of the sintered body described below is intended to embody the technical idea of ​​the present disclosure, and unless otherwise specified, the present disclosure is not limited to the following.

[0010] <Firing furnace> In this embodiment, limestone is calcined in a calcination furnace (calcination apparatus) to produce a calcined body such as quicklime or a material containing quicklime. The calcination furnace is not particularly limited, and examples include vertical calcination furnaces such as a Mertz furnace, a Beckenbach furnace, a co-firing furnace, a shaft kiln, and a top kiln, as well as horizontal calcination furnaces such as a rotary kiln. Of these, vertical calcination furnaces are preferred, and Beckenbach furnaces are particularly preferred. In a vertical calcination furnace, upward gas generated from fuel or the like comes into countercurrent contact with the limestone introduced and packed (piled) into the furnace. The calcination conditions are not particularly limited, and the calcination conditions for each calcination furnace can be used.

[0011] A calcination furnace has one or more inlets for introducing fuel and the like into the furnace. For example, a vertical calcination furnace has a cylindrical furnace body, an inlet (top inlet) at the top of the furnace body through which limestone and the like can be introduced into the furnace, a combustion chamber arranged along the outer periphery of the furnace body, and an inlet (side inlet: burner) arranged in the combustion chamber through which fuel can be introduced into the furnace from the side of the furnace body. A plurality of combustion chambers and burners may be arranged along the outer periphery of the furnace body. The plurality of burners may include a pair of burners arranged opposite each other on the outer periphery of the furnace body. For example, the combustion chambers and burners may include five lower combustion chambers and five lower burners arranged at a predetermined interval on the outer periphery of the furnace body, and five upper calcination chambers and five upper burners arranged above the lower combustion chambers and lower burners and arranged at a predetermined interval on the outer periphery of the calcination furnace.

[0012] <Method for manufacturing fired body> The method for producing a calcined body in this embodiment is a method for producing a calcined body obtained by calcining limestone, and includes a step (calcination step) of charging limestone together with lumped fuel into a calcination furnace, and then charging solid biomass fuel to calcinate the limestone.

[0013] Examples of biomass fuels include wood chips, sawdust, wood pellets, waste wood, thinned wood, sawdust, straw, rice husks, coconut shells, corn residue, bagasse, papermaking sludge, waste pulp, recycled paper, black liquor, semi-carbonized biomass, carbonized biomass, bioethanol, bio-derived methane, livestock excrement, and industrial waste. Examples of lump fuels that are added together with limestone include anthracite, coal coke, and petroleum coke.

[0014] Examples of coconut shells include those from palm trees (oil palms), coconut palms, salak palms, and omi palms. These coconut shells can be used alone or in combination. Palm trees are used as food, detergent raw materials, biodiesel raw materials, etc. Therefore, palm shells, which are the shells of coconut trees, are generated in large quantities as biomass waste. Carbonized biomass is carbonized raw materials (biomass) derived from living organisms, excluding fossil fuels such as petroleum, and examples include charcoal, bamboo charcoal, rice husk charcoal, black pellets, and biochar. Examples of industrial waste include waste plastics, waste oil, waste tires, RPF, construction waste, construction soil, waste gypsum, and waste lime.

[0015] As the biomass fuel, from the viewpoint of environmental consideration and efficient production of the fired body, it is preferable to use at least one of carbonized biomass, palm kernel shells, and wood pellets among the above.

[0016] The solid biomass fuel fed into the furnace is finely pulverized and in powder form. The method for producing a calcined body may include a pulverization step, prior to the calcination step, in which the biomass fuel is pulverized to a size that can be fed through the feed port. The particle size (average particle size) of the pulverized biomass fuel may be 5 mm or less and 0.1 mm or more, 3 mm or less and 0.3 mm or more, 2 mm or less and 0.5 mm or more, or even 1 mm. Setting the particle size within these ranges makes it easier to inject the biomass fuel into the calcination furnace from the burner that serves as the feed port of the calcination furnace. Furthermore, limestone can be efficiently calcined.

[0017] The method for feeding biomass fuel into the furnace is not particularly limited, but for example, the biomass fuel may be fed (sprayed) into the furnace from a burner together with a gas. This gas may be air, but gases other than air may also be used. The material may be fed from the furnace top inlet by, for example, transporting limestone mixed with lump fuel above the furnace top on a belt conveyor and feeding it into the furnace through the inlet at the top.

[0018] The temperature inside the furnace when biomass fuel is charged (charging temperature) can be changed as appropriate depending on the biomass fuel. This charging temperature may be, for example, 900°C or higher, 1000°C or higher, 1100°C or higher, 1150°C or higher, or 1200°C or higher. There is no particular upper limit to the charging temperature, but from the perspective of protecting the bricks of the firing furnace, a temperature of 1400°C or lower is desirable. This range allows for efficient calcination of limestone. It also allows for a stable temperature inside the furnace. [Example]

[0019] Specific examples of the present disclosure are shown below, but the present disclosure is not limited to these.

[0020] First, the firing furnace, materials, etc. used in this example will be described. [Firing furnace] A vertical Beckenbach furnace (maximum production capacity 200-400 t / day) was used. This furnace is equipped with five upper combustion chambers and upper burners, and five lower combustion chambers and lower burners (referred to as burner 1 to burner 5). Biomass fuel is fed into the furnace through burner 1, one of the five lower burners. [Limestone] The limestone used had a particle size of 40 mm to 70 mm. [Biomass fuel] The materials used were carbonized biomass produced in the United States (average particle size of 1mm or less (maximum 2mm)), palm kernel shells from Indonesia (crushed to an average particle size of 1mm or less (maximum 2mm)), and wood pellets from Indonesia (crushed to an average particle size of 1mm or less (maximum 2mm)). [Other fuels] Heavy oil (recycled oil) was used. [Fuel input from each burner] The start of firing was counted as day 1, and firing continued until day 5. Heavy oil was injected from burners other than burner 1 (burners 2 to 5 and the upper burner). Biomass fuel and heavy oil were injected from burner 1, switching between them as needed.

[0021] Example 1 Limestone was loaded into the kiln through the top inlet, along with anthracite (Russian) as lump fuel. Heavy oil was then loaded from each burner and ignited to calcine the limestone (for convenience, midnight of the following day is considered midnight on the first calcination day). The fuel loaded from the first burner in one of the lower combustion chambers was then switched from heavy oil to carbonized biomass, and the carbonized biomass was loaded into the furnace, where the limestone was calcined (11:00 on the first calcination day). The fuel loaded from the first burner was then switched back from carbonized biomass to heavy oil (4:00 on the first calcination day). The fuel loaded from the first burner was then switched back from heavy oil to carbonized biomass (9:30 on the second calcination day).

[0022] <Example 2> After Example 1, the fuel input from the first burner was switched from carbonized biomass to palm kernel shells (1:00 PM on the second day of burning). Next, the fuel input from the first burner was switched from palm kernel shells to heavy oil (4:00 PM on the second day of burning). After that, the fuel input from the first burner was switched from heavy oil back to palm kernel shells (9:00 AM on the third day of burning). Next, the fuel input from the first burner was switched from palm kernel shells back to heavy oil (11:30 AM on the third day of burning).

[0023] Example 3 After Example 2, the fuel charged from the first burner was switched from heavy oil to wood pellets (9:00 on the fourth day of firing). Next, the fuel charged from the first burner was switched from wood pellets to heavy oil (12:00 on the fourth day of firing). Thereafter, the fuel charged from the first burner was switched from heavy oil back to wood pellets (13:30 on the fourth day of firing). Next, the fuel charged from the first burner was switched from wood pellets back to heavy oil (16:00 on the fourth day of firing). Thereafter, the fuel charged from the first burner was switched from heavy oil back to wood pellets (9:00 on the fifth day of firing). Next, the fuel charged from the first burner was switched from wood pellets back to heavy oil (11:00 on the fifth day of firing).

[0024] <Comparative Example 1> Comparative Example 1 was conducted in the same manner as Example 1, except that heavy oil was fed into the furnace from a second burner located in one of the lower combustion chambers every day from the first to fifth firing days.

[0025] <Comparative Examples 2 to 4> Comparative Examples 2 to 4 were prepared for each burner in the same manner as Comparative Example 1, except that heavy oil was fed into the furnace using the third to fifth burners.

[0026] The above examples and comparative examples are summarized in Table 1. [Table 1]

[0027] [Evaluation of temperature and heat quantity of each combustion chamber against combustion time] For the above examples and comparative examples, the temperature of each combustion chamber was measured with respect to the combustion time. The temperature of each combustion chamber was measured using a thermocouple installed in the combustion chamber. The heat quantity in each combustion chamber (combustion chamber heat load) was calculated from the weight of fuel quantitatively discharged from the fuel tank and supplied to the burner. The results are shown in Figures 1A and 1B.

[0028] In Examples 1 to 3, even when biomass fuel was used instead of heavy oil, the combustion chamber temperature could be maintained at a high temperature (above 1100°C). In Examples 1 to 3, the combustion chamber temperature could be maintained at a constantly higher temperature than in Comparative Example 2 (third burner) and Comparative Example 4 (fifth burner), and could be maintained at a temperature equivalent to that of Comparative Example 1 (second burner) and Comparative Example 3 (fourth burner). When the carbonized biomass of Example 1 was used, the calorific value was lower than in Comparative Examples 1 to 4 when the burning date and time was between 11:00 and 16:00 on the first day.

[0029] [Evaluation of frame temperature and brightness] The flame temperature in the combustion chamber was measured when each fuel was used. The flame temperature was measured using an infrared thermometer. The brightness of each combustion chamber was also observed visually. The results for the flame temperature are shown in Figure 2. Note that "80% mixed combustion" means that 80% of the combustion chamber heat load is changed to the heat amount of biomass fuel supplied from the burner, and "100% mono-combustion" means that 100% of the heat load is changed in the same way.

[0030] In all cases, the flame temperature was over 1000°C. When carbonized biomass was used, the flame temperature was higher than when other biomass fuels (palm kernel shells, wood pellets) or heavy oil were used. When carbonized biomass was used, the flame temperature was over 1250°C in 80% co-firing and over 1300°C in 100% mono-firing. The brightness when carbonized biomass was used was higher than that of other biomass fuels.

[0031] [Evaluation of residual carbon dioxide and silicon dioxide in fired body] After calcining the limestone in the above Examples and Comparative Examples, quicklime (calcined body) was obtained from the bottom of each calcination furnace. The residual carbon dioxide and silicon dioxide contained in the quicklime obtained by calcining using the first burner (Examples 1 to 3) and the quicklime obtained by calcining using the third burner (Comparative Example 2) located on the opposite side of the first burner were measured using the method for quantifying silicon dioxide and insoluble residue (JIS R9011). The results are shown in Figures 3A and 3B. In the figures, the "+30mm" column represents the oversized particles sieved using a 30mm mesh, the "-5mm" column represents the undersized particles sieved using a 5mm mesh, and the "5-30mm" column represents the intermediate values.

[0032] When carbonized biomass was used as fuel, residual carbon dioxide was lower than when heavy oil was used. When palm kernel shells or wood pellets were used as fuel, residual carbon dioxide was equivalent to that when heavy oil was used. Silicon dioxide when using biomass fuel was equivalent to that when heavy oil was used (silicon dioxide in the range of -5mm for carbonized biomass and 5-30mm for palm kernel shells).

Claims

1. A method for producing a calcined body obtained by calcining limestone, comprising: The limestone is charged into a calcination furnace, and solid biomass fuel is charged therein to calcinate the limestone. Method for manufacturing a fired body.

2. The biomass fuel is finely pulverized. A method for producing the sintered body according to claim 1.

3. The particle size of the pulverized biomass fuel is 5 mm or less. A method for producing the fired body according to claim 2.

4. At least one of carbonized biomass, palm kernel shells, and wood pellets is used as the biomass fuel. A method for producing the fired body according to claim 1 or 2.

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