Manufacturing method for calcined bodies
The use of solid biomass fuels in the calcination of limestone addresses the need for environmentally friendly and efficient production of calcined bodies by maintaining high combustion temperatures and reducing emissions, optimizing the calcination process.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- UBE CHEM IND CO LTD
- Filing Date
- 2024-03-28
- Publication Date
- 2026-06-03
AI Technical Summary
Existing firing technologies face challenges in replacing fossil fuels with environmentally friendly alternatives and require more efficient fuel utilization, particularly in the production of calcined bodies like quicklime and calcined dolomite.
A method involving the calcination of limestone using solid biomass fuels such as wood chips, wood pellets, and carbonized biomass in a calcination furnace, with specific fuel switching strategies to optimize the calcination process.
This approach enables the production of environmentally friendly and efficient calcined bodies by maintaining high combustion temperatures and reducing residual carbon dioxide emissions, while ensuring stable furnace operation.
Smart Images
Figure 0007869824000002 
Figure 0007869824000003 
Figure 0007869824000004
Abstract
Description
Technical Field
[0001] The present disclosure relates to a method for manufacturing a fired body.
Background Art
[0002] Conventionally, when firing limestone, firing technologies have been developed that use fuels that can replace fossil fuels such as oil and coal, or suppress emissions of carbon dioxide and the like generated by fuel combustion, taking environmental considerations into account. For example, Patent Document 1 discloses a method for manufacturing quicklime and calcined dolomite, which includes a step of gasifying an organic substance such as waste plastic in a gas generation unit to generate a combustible gas, and a step of feeding the combustible gas generated in the above step into a firing furnace to generate quicklime or calcined dolomite.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] Regarding the firing technology of Patent Document 1, it is required to appropriately adopt a fuel that can replace fossil fuels and develop an environmentally friendly firing technology. Further, in Patent Document 1, it is necessary to once gasify the fuel in the gas generation unit, and more efficient firing of the fuel is required.
[0005] Therefore, an object of the present disclosure is to provide a method for manufacturing an environmentally friendly fired body, and another object is to provide a method for manufacturing an efficient fired body.
Means for Solving the Problems
[0006] The method for manufacturing a calcined body according to this disclosure is a method for manufacturing a calcined body obtained by calcining limestone, which involves placing the limestone into a calcination furnace and then adding solid biomass fuel to calcine the limestone. [Effects of the Invention]
[0007] This disclosure makes it possible to provide an environmentally friendly method for manufacturing fired products. It also makes it possible to provide an efficient method for manufacturing fired products. [Brief explanation of the drawing]
[0008] [Figure 1A] Graph showing the temperature of each combustion chamber in relation to firing time. [Figure 1B] Graph showing the heat load of each combustion chamber in relation to firing time. [Figure 2] Graph showing flame temperature when using each fuel. [Figure 3A] Graph showing residual carbon dioxide in calcined bodies obtained using each fuel. [Figure 3B] Graph showing silicon dioxide content in calcined bodies obtained using each fuel. [Modes for carrying out the invention]
[0009] <Embodiment> Embodiments of this disclosure will be described in detail below. The manufacturing method of the fired body described below is intended to embody the technical concept of this disclosure, and unless otherwise specified, this disclosure is not limited to the following.
[0010] <Kiln> In this embodiment, quicklime or a calcined body containing quicklime is produced by calcining limestone in a calcination furnace (calcination apparatus). The calcination furnace is not particularly limited and examples include vertical calcination furnaces such as Merz furnaces, Beckenbach furnaces, mixed calcination furnaces, shaft kilns, and spool-type furnaces, as well as horizontal calcination furnaces such as rotary kilns. Among these, vertical calcination furnaces are preferred, and Beckenbach furnaces are particularly preferred. In a vertical calcination furnace, upward gas generated from fuel etc. inside the furnace comes into countercurrent contact with the limestone that has been introduced and filled (deposited) into the furnace. The calcination conditions are not particularly limited and the calcination conditions of each calcination furnace can be used.
[0011] A firing furnace is equipped with one or more input ports for introducing fuel into the furnace. For example, in the case of a vertical firing furnace, it comprises a cylindrical furnace body, an input port at the top of the furnace body into which limestone or the like can be introduced (top input port), a combustion chamber arranged along the outer circumference of the furnace body, and an input port in the combustion chamber that allows fuel to be introduced into the furnace from the side of the furnace body (side input port: burner). Multiple combustion chambers and burners may be arranged along the outer circumference of the furnace body. Multiple burners may include a pair of burners that are positioned opposite each other on the outer circumference of the furnace body. For example, the combustion chambers and burners may include five lower combustion chambers and five lower burners arranged at predetermined intervals on the outer circumference of the furnace body, and five upper firing chambers and five upper burners arranged above the lower combustion chambers and lower burners, and arranged at predetermined intervals on the outer circumference of the firing furnace.
[0012] <Method for manufacturing a fired body> The method for manufacturing a calcined body in this embodiment is a method for manufacturing a calcined body obtained by calcining limestone, and includes a step (calcination step) in which limestone is placed in a calcination furnace together with a lump of fuel, and solid biomass fuel is placed in to calcine the limestone.
[0013] Examples of biomass fuels include wood chips, wood waste, wood pellets, waste wood, thinned wood, sawdust, straw, rice husks, coconut husks, corn residue, bagasse, papermaking sludge, waste pulp, recycled paper, black liquor, semi-carbonized biomass, carbonized biomass, bioethanol, bio-derived methane, livestock waste, 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 oil, coconut, salak, and sea oak. These coconut shells can be used individually or in combination. Palm oil is used as a raw material for food, detergents, and biodiesel oil. Therefore, palm oil shells are a large amount of biomass waste. Carbonized biomass is made by carbonizing raw materials (biomass) that are derived from living organisms, excluding fossil fuels such as petroleum. Examples include wood 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 for biomass fuel, from the viewpoint of being environmentally conscious and efficiently producing calcined products, it is preferable to use at least one of the above: carbonized biomass, palm kernel shells, and wood pellets.
[0016] The solid biomass fuel fed into the furnace is finely pulverized and in powder form. The manufacturing method for the calcined body may include a pulverization step before the calcination process in which the biomass fuel is finely pulverized to a size that can be fed through the inlet. The particle size (average particle diameter) 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 1 mm. By setting the particle size within this range, it is possible to easily inject the biomass fuel into the calcination furnace from the burner which serves as the inlet of the calcination furnace. In addition, it is possible to calcine the limestone efficiently.
[0017] The method of charging biomass fuel into the furnace is not particularly limited. For example, the biomass fuel may be charged (injected) into the furnace from a burner together with a gas. Examples of this gas include air, but other gases may also be used. The charging of materials from the top charging port of the furnace may be carried out by conveying limestone premixed with lump-shaped fuel, for example, to above the top of the furnace using a belt conveyor and then charging it into the furnace through the top charging port.
[0018] The temperature inside the furnace (charging temperature) when charging the biomass fuel can be appropriately changed depending on the biomass fuel. This charging temperature may be, for example, 900 degrees or higher, 1000 degrees or higher, 1100 degrees or higher, 1150 degrees or higher, or 1200 degrees or higher. The upper limit of the charging temperature is not particularly limited, but from the perspective of protecting the bricks of the firing furnace, it is preferably 1400 degrees or lower. According to such a range, efficient firing of limestone becomes possible. Also, the temperature inside the furnace can be stabilized.
Examples
[0019] Specific examples of the present disclosure are shown below, but these do not limit the present disclosure.
[0020] First, the firing furnace, materials, etc. used in this example are shown. [Firing Furnace] A Beckenbach furnace, which is a vertical firing furnace (maximum production capacity: 200 - 400 t / day), was used. This firing furnace has five upper combustion chambers and upper burners, and five lower combustion chambers and lower burners (designated as the first burner to the fifth burner). Biomass fuel is charged into the furnace from the first burner, which is one of the five lower burners. [Limestone] Limestone with a particle size of 40 mm to 70 mm was used. [Biomass Fuel] The materials used were one of the following: carbonized biomass produced in the United States (average particle size 1 mm or less (maximum 2 mm)), palm kernel shells from Indonesia (ground to an average particle size of 1 mm or less (maximum 2 mm)), or wood pellets from Indonesia (ground to an average particle size of 1 mm or less (maximum 2 mm)). [Other fuels] Heavy oil (recycled oil) was used. [Fuel input from each burner] The firing process was carried out from day 1 to day 5. Heavy oil was injected from all burners except the first burner (burners 2 through 5, and the upper burner). From the first burner, biomass fuel and heavy oil were injected, switching between them as needed.
[0021] <Example 1> Limestone, along with chunks of anthracite (from Russia) as fuel, was loaded into the furnace through the top inlet and filled. Heavy oil was then added from each burner to ignite the mixture, and the limestone was fired (for convenience, midnight on the following day will be considered midnight on day 1 of firing). Subsequently, the fuel supplied from the first burner located in one of the lower combustion chambers was switched from heavy oil to carbonized biomass, and carbonized biomass was added to the furnace to fire the limestone (11:00 on day 1 of firing). After that, the fuel supplied from the first burner was switched back from carbonized biomass to heavy oil (16:00 on day 1 of firing). Next, the fuel supplied from the first burner was switched back from heavy oil to carbonized biomass (9:30 on day 2 of firing).
[0022] <Example 2> Following Example 1, the fuel supplied to the first burner was switched from carbonized biomass to palm kernel shells (13:00 on the second day of firing). Next, the fuel supplied to the first burner was switched from palm kernel shells to heavy oil (16:00 on the second day of firing). Subsequently, the fuel supplied to the first burner was switched back from heavy oil to palm kernel shells (9:00 on the third day of firing). Next, the fuel supplied to the first burner was switched back from palm kernel shells to heavy oil (11:30 on the third day of firing).
[0023] <Example 3> After Example 2, the fuel supplied to the first burner was switched from heavy oil to wood pellets (9:00 AM on the 4th day of firing). Next, the fuel supplied to the first burner was switched from wood pellets to heavy oil (12:00 PM on the 4th day of firing). After that, the fuel supplied to the first burner was switched back from heavy oil to wood pellets (1:30 PM on the 4th day of firing). Next, the fuel supplied to the first burner was switched back from wood pellets to heavy oil (4:00 PM on the 4th day of firing). After that, the fuel supplied to the first burner was switched back from heavy oil to wood pellets (9:00 AM on the 5th day of firing). Next, the fuel supplied to the first burner was switched back from wood pellets to heavy oil (11:00 AM on the 5th day of firing).
[0024] <Comparative Example 1> Comparative Example 1 was constructed in the same manner as Example 1, except that heavy oil was introduced into the furnace from a second burner located in one of the lower combustion chambers throughout the day from the first to the fifth day of firing.
[0025] <Comparative Examples 2 to 4> Comparative Examples 2 through 4 were conducted in the same manner as in Comparative Example 1, except that heavy oil was introduced into the furnace using the third through fifth burners.
[0026] The above examples and comparative examples are summarized in Table 1. [Table 1]
[0027] [Evaluation of temperature and heat quantity in each combustion chamber in relation to 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 inside the combustion chamber. The heat quantity in each combustion chamber (combustion chamber heat load) was calculated from the weight of the 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 (1100 degrees Celsius or higher). In Examples 1 to 3, the combustion chamber temperature was consistently higher than that of Comparative Example 2 (third burner) and Comparative Example 4 (fifth burner), and was equivalent to that of Comparative Example 1 (second burner) and Comparative Example 3 (fourth burner). When carbonized biomass was used in Example 1, the amount of heat was lower compared to Comparative Examples 1 to 4 when the firing time was from 11:00 to 16:00 on the first day.
[0029] [Evaluation of frame temperature and brightness] The flame temperature of the combustion chamber was measured when each fuel was used. The flame temperature was measured using an infrared radiation thermometer. In addition, the brightness of each combustion chamber was observed visually. The results for flame temperature are shown in Figure 2. Note that "80% co-firing" means that 80% of the heat load of the combustion chamber was changed to the heat load of biomass fuel supplied from the burner, and "100% pure firing" means that 100% of the heat load was changed in the same way.
[0030] In all fuel cases, the flame temperature was above 1000 degrees Celsius. When carbonized biomass was used, the flame temperature was higher compared to when other biomass fuels (palm kernel shells, wood pellets) or heavy oil were used. When carbonized biomass was used, the flame temperature was above 1250 degrees Celsius with 80% co-firing and above 1300 degrees Celsius with 100% pure carbonized biomass. The brightness when carbonized biomass was used was higher than with other biomass fuels.
[0031] [Evaluation of residual carbon dioxide and silicon dioxide in calcined materials] After calcining the limestone in the above examples and comparative examples, quicklime (calcined body) was obtained from the bottom of the calcination furnace in each case. The residual carbon dioxide and silicon dioxide contained in the quicklime obtained by calcining with the first burner (Examples 1-3) and the quicklime obtained by calcining with the third burner located on the opposite side of the first burner (Comparative Example 2) were measured according to the quantitative method for silicon dioxide and insoluble residue (JIS R9011). The results are shown in Figures 3A and 3B. In the figures, the "+30mm" item represents the top of the sieve after sieving with a 30mm mesh, the "-5mm" item represents the bottom of the sieve after sieving with a 5mm mesh, and the "5-30mm" item represents the intermediate value.
[0032] When carbonized biomass was used as fuel, the residual carbon dioxide levels were lower compared to when heavy oil was used. When palm kernel shells or wood pellets were used as fuel, the residual carbon dioxide levels were comparable to those of heavy oil. The silicon dioxide levels when using biomass fuel were comparable to those of heavy oil (silicon dioxide levels in the -5mm range for carbonized biomass and in the 5-30mm range for palm kernel shells).
Claims
1. A method for producing a calcined body obtained by calcining limestone, The process includes the step of placing the limestone into a Beckenbach furnace equipped with multiple burners, and then adding heavy oil and solid biomass fuel to calcine the limestone, In the above process, among the plurality of burners, In at least one burner, the heavy oil and the biomass fuel are alternately switched and supplied into the furnace, In other burners, the heavy oil is supplied into the furnace. A method for manufacturing a fired body.
2. The aforementioned biomass fuel is finely ground. A method for producing a fired body according to claim 1.
3. The particle size of the finely pulverized biomass fuel is 5 mm or less. The method for producing a fired body according to claim 2.
4. As the biomass fuel, at least one of carbonized biomass, palm kernel shells, and wood pellets is used. A method for producing a fired body according to claim 1 or 2.
5. The plurality of burners comprises an upper burner and a plurality of lower burners located below the upper burner, In the above process, at least one of the plurality of lower burners is supplied to the furnace by alternately switching between the heavy oil and the biomass fuel, In the upper burner and among the plurality of lower burners, the heavy oil is supplied into the furnace. A method for producing a fired body according to claim 1 or 2.