Combustion system and combustion method

Abstract

To effectively suppress flow defects caused by agglomeration in the fluidized medium that forms the fluidized bed in a combustion furnace. [Solution] The combustion system comprises a combustion furnace that forms a fluidized bed with a fluid medium containing silica sand particles and burns a fuel containing alkali metals in the fluidized bed; an inhibitor input unit that introduces an inhibitor to the combustion furnace that suppresses agglomeration of the silica sand particles, which is produced from used high-alumina products or scraps generated in the manufacturing process of high-alumina products; and a control device that controls the amount of the inhibitor introduced by the inhibitor input unit based on information about the operating status of the combustion furnace, wherein the inhibitor is composed of particles with a particle size of 1 μm or more and 800 μm or less.

Description

Technical Field

[0001] The present invention relates to a combustion system and a combustion method.

Background Art

[0002] As a method for generating electric power using biomass as fuel, there is a method using a fluidized bed furnace. A fluidized bed furnace forms a fluidized bed in which a high-temperature fluidizing medium is fluidized by upwardly blown fluidizing air, and burns the fuel supplied into the furnace in the fluidized bed. As biomass serving as fuel, for example, plant-derived and low-cost biomass such as empty fruit bunches (EFB) of oil palm is attracting attention. However, when power generation is performed by burning empty fruit bunches of oil palm in a fluidized bed furnace, the following problems occur.

[0003] Empty fruit bunches of oil palm contain a large amount of alkali metals such as sodium and potassium. When silica sand is used as the fluidizing medium of the fluidized bed furnace, for example, gaseous potassium released from the empty fruit bunches of oil palm in the fluidized bed furnace reacts with silicon oxide of the silica sand particles, and a SiO₂-K₂O compound is generated on the surfaces of the silica sand particles. Since the melting temperature of this SiO₂-K₂O compound is lower than the temperature in the fluidized bed furnace, it melts to form an adhesive layer on the surfaces of the silica sand particles. When this adhesive layer is formed, several silica sand particles are fused to each other, and when aggregation and agglomeration of the silica sand occur, the silica sand stops flowing, which hinders the normal operation of the fluidized bed furnace. Therefore, as inventions for solving such problems, there are techniques disclosed in, for example, Patent Documents 1 and 2, and Non-Patent Document 1.

[0004] In the technique disclosed in Patent Document 1, the fluidizing medium is composed of particulate mineral and / or particulate slag, and the content of quartz is set to 14 mass% or less. Since the amount of quartz contained in the fluidizing medium is 14 mass% or less, even if the quartz in the fluidizing medium reacts with the alkali metal component in the fuel to form an adhesive layer on the particle surfaces, aggregation or agglomeration of the fluidizing medium does not occur, or is slight even if it occurs, and the fluidized bed can maintain favorable fluidity.

[0005] In the technology disclosed in Patent Document 2, the fluidizing gas velocity inside the fluidized bed furnace is controlled to be close to 4 m / s, and the blow-up status of the fluidized medium near the outlet of the fluidized bed furnace is detected by a laser monitoring device. The amount of incineration air corresponding to the blow-up status is then fed back to the combustion air supply side. By increasing the fluidizing gas velocity inside the fluidized bed furnace to about 4 m / s, the critical salt accumulation amount in the fluidized medium can be increased, thereby increasing the amount of waste that can be processed without causing fluidization problems in the fluidized bed.

[0006] Non-patent document 1 discloses various additives for solving operational problems that occur when burning biomass.

[0007] Furthermore, the technology disclosed in Patent Document 3 uses artificially manufactured spherical refractory particles as a fluid medium, having a chemical composition containing 40% or more by weight of Al2O3 and 60% or less by weight of SiO2. The fluid medium, which has swelled or solidified due to the adhesion of low-melting-point substances such as SiO2-K2O compounds, is rapidly cooled after being removed from the fluidized bed furnace, and then polished to separate the amorphous low-melting-point substances adhering to the fluid medium. This enables effective regeneration of the fluid medium. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2013-121562 [Patent Document 2] Special Publication No. 2019-511360 [Patent Document 3] Patent No. 7422131 [Non-patent literature]

[0009] [Non-Patent Document 1] Liang Wang, et al.; A critical review on additives to reduce ash related operation problems in biomass combustion applications, Energy Procedia, 20(2012) pp.20-29 [Overview of the project] [Problems that the invention aims to solve]

[0010] However, publicly available technologies still have room for improvement in terms of inexpensively and effectively suppressing flow problems caused by agglomeration.

[0011] The present invention has been made in view of the above, and its purpose is to suppress flow defects due to agglomeration in a fluidized medium that forms a fluidized bed in a combustion furnace in an inexpensive and effective manner. [Means for solving the problem]

[0012] To solve the above-mentioned problems and achieve the objective, one aspect of the present invention is a combustion system comprising: a combustion furnace that forms a fluidized bed with a fluid medium containing silica sand particles and burns a fuel containing alkali metals in the fluidized bed; an inhibitor input unit that introduces an inhibitor to the combustion furnace that suppresses agglomeration of the silica sand particles, produced from used high-alumina products or scraps generated in the manufacturing process of high-alumina products; and a control device that receives information on the operating status of the combustion furnace and controls the amount of the inhibitor introduced by the inhibitor input unit based on the input operating status information, wherein the inhibitor is composed of particles with a particle size of 1 μm or more and 800 μm or less.

[0013] In one aspect of the present invention, the inhibitor may consist of particles with a particle size of 300 μm or less.

[0014] In one aspect of the present invention, the information on the operating state of the combustion furnace may be at least one of the following: the amount of alkali metal contained in the fuel fed into the combustion furnace, the furnace bottom temperature of the combustion furnace, the furnace top temperature of the combustion furnace, the amount of residue withdrawn from the furnace bottom of the combustion furnace, the amount of new fluid medium fed into the combustion furnace, the amount of regenerated fluid medium selected from the residue withdrawn from the furnace bottom of the combustion furnace and fed into the combustion furnace, and the pressure loss in the combustion furnace.

[0015] One aspect of the present invention is a combustion method using a combustion furnace in which a fluidized bed is formed by a fluidized medium containing silica sand particles and a fuel containing alkali metals is burned in the fluidized bed, comprising: an inhibitor input step of introducing an inhibitor produced from used high-alumina products or scraps generated in the manufacturing process of high-alumina products into the combustion furnace; and a control step of controlling the amount of inhibitor introduced in the inhibitor input step based on information on the operating status of the combustion furnace obtained, wherein the inhibitor is composed of particles with a particle size of 1 μm or more and 800 μm or less.

[0016] In one aspect of the present invention, the information on the operating state of the combustion furnace may be at least one of the following: the amount of alkali metal contained in the fuel fed into the combustion furnace, the furnace bottom temperature of the combustion furnace, the furnace top temperature of the combustion furnace, the amount of residue withdrawn from the furnace bottom of the combustion furnace, the amount of new fluid medium fed into the combustion furnace, the amount of regenerated fluid medium selected from the residue withdrawn from the furnace bottom of the combustion furnace and fed into the combustion furnace, and the pressure loss in the combustion furnace. [Effects of the Invention]

[0017] According to the present invention, flow defects due to agglomeration in a fluidized medium that forms a fluidized bed in a combustion furnace can be suppressed inexpensively and effectively. [Brief explanation of the drawing]

[0018] [Figure 1] Figure 1 is a diagram showing the configuration of a combustion system according to an embodiment. [Figure 2]Figure 2 is a diagram showing an example of the relationship between the average particle size of the inhibitor and the addition ratio (%) of the inhibitor required for the fluidizing medium to maintain fluidization. [Mode for Carrying Out the Invention]

[0019] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments described below.

[0020] (Embodiment) [Configuration of Combustion System] Figure 1 is a diagram showing the configuration of a combustion system 1000 according to an embodiment of the present invention. The combustion furnace 1 is a Circulating Fluidized Bed (CFB) type furnace. The combustion furnace 1 is a furnace in which a fluidizing medium is caused to flow inside to form a fluidized bed, and fuel supplied into the combustion furnace 1 is combusted in the fluidized bed. The combustion furnace 1 is mainly composed of a riser 10 as the furnace main body, and a downcomer 20 that collects part of the fluidizing medium and returns it to the riser 10.

[0021] The riser 10 is provided at its lower portion with an air diffuser pipe 11 for blowing primary air supplied from a blower 81 upward. Further, on the side wall of the lower portion of the riser 10, a first inlet 12 for introducing the fluidizing medium into the riser 10 above the air diffuser pipe 11, a second inlet 13 for introducing fuel and inhibitor into the riser 10, and a secondary air blowing port 14 for blowing secondary air supplied from a blower 82 into the riser 10 are provided in order from the lower side. In addition, a discharge unit 15 for discharging the fluidizing medium and furnace bottom ash inside the riser 10 is provided at the bottom of the riser 10. The fluidizing medium and furnace bottom ash are examples of retained matter discharged from the discharge unit 15.

[0022] The downcomer 20 is connected to the upper part of the riser 10 by piping 30. The downcomer 20 has a collection section 21 for collecting the fluid medium sent from the riser 10 along with the exhaust gas, a return pipe 22 for returning the fluid medium collected in the collection section 21 back to the lower part of the riser 10, and a sealing section 23 for preventing the gas from the riser 10 from rising inside the collection section 21.

[0023] The fuel feeder 40 is a device that stores the fuel to be burned in the riser 10 and sends it to the second feed port 13. The fuel is an alkali metal-containing fuel, such as biomass such as empty palm fruit bunches.

[0024] The inhibitor dispenser 50 is a device that stores an inhibitor in the riser 10 to suppress agglomeration of the fluid medium and sends it to the second inlet 13. The inhibitor suppresses agglomeration by raising the melting point of compounds that cause agglomeration, such as SiO2-K2O compounds. The inhibitor dispenser 50 is an example of an inhibitor dispenser.

[0025] A circulation line 60 is provided near the combustion furnace 1 to return the fluidized medium discharged from the discharge section 15 to the combustion furnace 1. The circulation line 60 is equipped with a sieving device 61, a mass measuring instrument 62, and a fluidized medium input machine 63, in that order from the discharge section 15.

[0026] The sieving device 61 receives the accumulated material discharged from the discharge section 15, separates the fluidized medium with a predetermined particle size or smaller that has passed through the sieve, and sends it to the mass measuring instrument 62. The particle size of the fluidized medium that passes through the sieve is, for example, 1 mm or less. The fluidized medium selected from such accumulated material is sometimes referred to as recycled fluidized medium. The sieving device 61 also sends clumps of fluidized medium that have become larger in diameter than the predetermined particle size due to agglomeration and have not passed through the sieve, as well as non-combustible materials generated after the combustion of fuel, to a waste line (not shown).

[0027] The mass measuring instrument 62 measures the mass of the recycled fluid medium sorted by the sieving device 61. The mass measuring instrument 62 is installed, for example, on a conveyor that transports the recycled fluid medium. The mass measuring instrument 62 outputs mass data indicating the measurement result to the control device 100, which will be described later.

[0028] The fluid medium dispenser 63 is a device that mixes unused fluid medium (hereinafter sometimes referred to as new fluid medium) supplied from the fluid medium supplyer 70, which will be described later, with recycled fluid medium whose mass has been measured by the mass measuring instrument 62, and sends the mixture to the first inlet 12.

[0029] The fluid medium supply machine 70 stores new fluid medium and supplies it to the fluid medium input machine 63. In this embodiment, the fluid medium is silica sand particles. Silica sand particles are particles whose main component is silicon oxide. For example, silica sand particles have a silica component ratio of 90% or more, and the component other than silica is, for example, alumina (Al2O3). Such silica sand particles are particles made of minerals such as quartz. Furthermore, the shape of the silica sand particles is preferably spherical with no corners. When the shape of the fluid medium is spherical, equipment wear is less likely to occur even if it collides with pipes or combustion furnace walls. Spherical silica sand particles can be manufactured, for example, by calcining raw materials. Furthermore, the particle size of the silica sand particles is, for example, 600 μm or less.

[0030] The riser 10 is also equipped with pressure sensors 91 and 93 and temperature sensors 92 and 94. Pressure sensors 91 and 93 are for measuring the differential pressure between the bottom and top of the riser 10, that is, the differential pressure or pressure loss of the riser 10. Pressure sensor 91 measures the pressure at the bottom of the riser 10, and pressure sensor 93 measures the pressure at the top of the riser 10. Pressure sensors 91 and 93 output pressure data indicating the measurement results to the control device 100. Temperature sensors 92 and 94 are for measuring the temperature inside the riser 10. Temperature sensor 92 is installed at the bottom of the riser 10 and measures the temperature at the bottom of the riser 10. Temperature sensor 94 is installed at the top of the riser 10 and measures the temperature at the top of the riser 10. Temperature sensors 92 and 94 output temperature data indicating the measurement results to the control device 100.

[0031] The control device 100 comprises a control unit 101, an operation unit 102, a display unit 103, and an interface 104. The control unit 101 comprises an arithmetic unit and a memory unit. The arithmetic unit is composed of, for example, a CPU (Central Processing Unit). The memory unit comprises, for example, a part composed of ROM (Read Only Memory) and a part composed of RAM (Random Access Memory). The part composed of ROM stores various programs and data used by the arithmetic unit to perform arithmetic processing. RAM is used to store the workspace for the arithmetic unit when it performs arithmetic processing and the results of the arithmetic processing performed by the arithmetic unit.

[0032] The control unit 101 controls the discharge unit 15, fuel injector 40, inhibitor injector 50, fluid medium injector 63, fluid medium supplyer 70, blowers 81 and 82, etc., by having the CPU execute a program stored in ROM. The functions of the control unit 101 are realized as a functional unit by the CPU reading and executing a program from ROM.

[0033] The operation unit 102 has a keyboard, mouse, and various buttons for operating the control device 100, and is operated by the operator of the combustion system 1000. The display unit 103 is, for example, a display device and displays various information related to the control performed by the control device 100. The operation unit 102 and the display unit 103 may be implemented by a touch panel display device. The interface 104 is controlled by the control unit 101 and outputs control signals to the controlled object. The interface 104 also acquires mass data from the mass measuring instrument 62, pressure data from pressure sensors 91 and 93, and temperature data from temperature sensors 92 and 94.

[0034] The inhibitor production facility 110 is equipment for producing inhibitors. The inhibitor produced in the inhibitor production facility 110 is transported to the inhibitor dispenser 50 and stored there.

[0035] [Inhibitors] Next, the inhibitor in this embodiment will be described in detail. The inhibitor is produced in the inhibitor production equipment 110 from used high-alumina products or scraps generated in the manufacturing process of high-alumina products. Used high-alumina products are, for example, used high-alumina bricks, or waste bricks. Scraps generated in the manufacturing process of high-alumina products are, for example, scraps generated when cutting raw materials to manufacture high-alumina products, or dust collected during cutting. These used materials and scraps are crushed into particles of the particle size described later. In some cases, if it is dust, further crushing may not be necessary. The inhibitor produced in this way can be prepared at a relatively low cost.

[0036] Furthermore, the inhibitor production equipment 110 may be equipment attached to equipment that uses high-alumina products (for example, a furnace), and may use high-alumina products that have been used in said equipment. Alternatively, the inhibitor production equipment 110 may be equipment attached to equipment that manufactures high-alumina products, and may use scraps generated from high-alumina products manufactured in said equipment.

[0037] Furthermore, in this specification, a high-alumina product refers to a product in which the alumina content is between 40% by mass and 99.8% by mass, for example, a product with about 60% alumina. Such products are manufactured using minerals such as bauxite, van shale, sillimanite, kyanite, andalusite, mullite, kaolinite, halosite, zeolite, bentonite, clay, aluminum sulfate, ammonium sulfate, iron sulfate, phosphate compounds, calcium oxide, calcium carbonate, sludge, coal ash, dolomite, bauxite, and titanium oxide as raw materials.

[0038] The inhibitor produced in this manner consists of particles with a particle size of 1 μm to 800 μm. This ensures that the inhibitor introduced into riser 10 effectively contributes to the suppression of agglomeration. If the particle size of the inhibitor is less than 1 μm, the inhibitor may be blown away in the fluidized bed and leak out accompanied by the exhaust gas, reducing the reaction efficiency of agglomeration suppression within riser 10. Furthermore, if the particle size of the inhibitor exceeds 800 μm, non-uniformity of the fluidization state in the fluidized bed may occur, raising concerns about unstable operation.

[0039] Furthermore, the inventors' diligent research has shown that a relatively small particle size of the inhibitor is preferable. The inventors investigated the relationship between the average particle size of the inhibitor and the amount of inhibitor needed to maintain the fluidity of the fluid medium using a combustion furnace with the configuration shown in Figure 1. Specifically, simulated fuel, simulated ash containing 20% ​​by mass of potassium oxide, and kaolin as an inhibitor were added to the combustion furnace with the configuration shown in Figure 1, and the amount of inhibitor needed to maintain the fluidity of the fluid medium for more than 3 hours at a furnace bottom temperature of 1050°C was investigated. Here, the amount of inhibitor to be added is the amount added relative to the fluid medium (by mass). The cessation of the fluidity state was confirmed by three methods. These methods included visually observing the inside of the furnace to determine whether or not fluidity was occurring, measuring the furnace temperature to determine whether or not there was a significant temperature change, and determining whether or not there was a change in furnace pressure. In the tests, all methods met the criteria.

[0040] Figure 2 shows an example of the relationship between the average particle size of the inhibitor and the percentage of inhibitor needed to maintain fluidity in the fluidized medium. As shown in Figure 2, it was confirmed that a smaller average particle size of the inhibitor results in a smaller percentage of inhibitor being needed, i.e., a smaller amount of inhibitor is required to maintain fluidity in the fluidized bed, thus demonstrating a higher inhibitory effect. In particular, the inhibitor is preferably composed of particles with a particle size of 300 μm or less, and more preferably composed of particles with a particle size of less than 25 μm.

[0041] [Control by a control device] Next, the operation of the combustion system will be explained, and the control by the control device 100 will be described in detail. In the combustion furnace 1, the control device 100 controls the blower 81 to blow primary air into the riser 10 from the diffuser pipe 11, and the control device 100 controls the blower 82 to blow secondary air into the riser 10 from the secondary air inlet 14. As a result, a fluidized bed in which the fluidizing medium is fluidized is formed inside the riser 10.

[0042] Furthermore, the fuel feeder 40 and inhibitor feeder 50, controlled by the control device 100, feed fuel and inhibitor into the riser 10 from the second feed port 13 (inhibitor feeding step). Here, the inhibitor is an inhibitor produced in the inhibitor production step from used high-alumina products or scraps generated in the manufacturing process of high-alumina products, and is produced in the inhibitor production equipment 110 and transported to the inhibitor feeder 50.

[0043] The fluidized medium becomes fluid due to the primary air blown in from the diffuser pipe 11, forming a dense layer of the fluidized medium in the lower part of the riser 10. In this dense layer, the high heat capacity and stirring effect promote the drying of the fuel and the release of volatile components. In the upper part of the riser 10, the fluidized medium is blown upward by the blowing in of primary and secondary air, forming a dilute layer of the fluidized medium. In this dilute layer, the fuel 73 is burned due to the heat capacity and stirring effect of the fluidized medium. In other words, the combustion furnace 1 prevents the generation of char, which is unburned carbon, and burns the fuel efficiently by forming a fluidized bed consisting of a dense layer and a dilute layer in the riser 10. The combustion region in the riser 10 is maintained at approximately 850-900°C.

[0044] The exhaust gas generated by the combustion of fuel in the riser 10 is supplied to the collection section 21 of the downcomer 20 via the piping 30. A portion of the fluidized medium is also sent from the riser 10 to the collection section 21 along with the exhaust gas. In the collection section 21, the fluidized medium and relatively large-particle ash are collected and returned to the bottom of the riser 10 through the seal section 23 and the return pipe 22. The exhaust gas and relatively small-particle ash are discharged from the top of the downcomer 20 and sent to the exhaust gas treatment facility via a superheater (not shown). The steam is superheated in the superheater, and after dust removal in the exhaust gas treatment facility, it is released to the outside through a chimney (not shown).

[0045] In this embodiment, the fuel burned in the riser 10 releases gaseous potassium, which is an alkali metal component. This gaseous potassium reacts with silica contained in the fluid medium, forming an SiO2-K2O compound on the surface of the fluid medium. However, in this embodiment, the melting point of the SiO2-K2O compound is raised by the action of the inhibitor, so the fusion of the fluid mediums is suppressed.

[0046] However, some of the fluid medium fuses with the SiO2-K2O compound and falls to the bottom of the riser 10. The fused and fallen fluid medium then fuses further to form a mass. This mass, along with the fluid medium and the non-combustible material remaining after the combustion of the fuel, is discharged from the discharge section 15 at regular intervals and sent to the sieving device 61.

[0047] The sieving device 61 receives the accumulated material and separates the fluid medium (regenerated fluid medium) with a particle size of a predetermined size or smaller that has passed through the sieve, sending it to the mass measuring device 62. The mass measuring device 62 measures the mass of the recycled fluid medium. Note that the recycled fluid medium may have some degree of compounds that cause agglomeration attached to it.

[0048] The control device 100 controls the fluid medium supply machine 70 to supply a predetermined amount of new fluid medium to the fluid medium dispenser 63. The control device 100 controls the fluid medium dispenser 63 to send a predetermined amount of fluid medium, including new fluid medium and recycled fluid medium, to the first inlet 12. As a result, fluid medium is introduced into the riser 10 from the first inlet 12 and replenished.

[0049] Here, the control device 100 receives information about the operating status of the combustion furnace 1. Based on the input and known operating status information, the control device 100 executes a control step to control the amount of inhibitor dispensed by the inhibitor dispenser 50. As a result, an appropriate amount of inhibitor is dispensed according to the operating status of the combustion furnace 1, effectively suppressing flow problems caused by agglomeration.

[0050] The information regarding the operating status of the combustion furnace 1 may include at least one of the following: the amount of alkali metal contained in the fuel fed into the riser 10 of the combustion furnace 1, the furnace bottom temperature of the riser 10, the furnace top temperature of the riser 10, the amount of retained material withdrawn from the furnace bottom of the riser 10, the amount of new fluidized medium fed into the riser 10, the amount of recycled fluidized medium fed into the riser 10, and the pressure drop in the riser 10.

[0051] The amount of alkali metals (especially potassium) contained in the fuel introduced into the riser 10 of the combustion furnace 1 can be, for example, the amount of alkali metal components listed in the fuel quality sheet. This component amount may differ from one fuel lot to another, but the operator may store it in the control unit 101 by operating the control unit 102 of the control device 100. For example, if the amount of alkali metals increases, agglomeration becomes more likely to occur, so the control device 100 increases the amount of inhibitor. This effectively suppresses flow problems caused by agglomeration. Also, if the amount of alkali metals decreases, the control device 100 can suppress excessive use of inhibitor by decreasing the amount of inhibitor.

[0052] Furthermore, for example, if the furnace bottom temperature or furnace top temperature of the riser 10 increases, agglomeration becomes more likely to occur, so the control device 100 increases the amount of inhibitor. This effectively suppresses flow problems caused by agglomeration. Also, if the furnace bottom temperature or furnace top temperature decreases, the control device 100 can reduce the amount of inhibitor, thereby preventing excessive use of the inhibitor.

[0053] Furthermore, for example, if the amount of retained material drawn from the bottom of the riser 10 increases, it indicates that agglomeration is occurring more frequently, so the control device 100 increases the amount of inhibitor. This effectively suppresses flow problems caused by agglomeration. Also, if the amount of retained material decreases, the control device 100 can reduce the amount of inhibitor, thereby preventing excessive use of the inhibitor.

[0054] Furthermore, for example, if the amount of new fluid medium introduced into the riser 10 increases, agglomeration is more likely to occur, so the control device 100 increases the amount of inhibitor. This effectively suppresses poor flow due to agglomeration. Also, if the amount of new fluid medium decreases, the control device 100 can prevent excessive use of the inhibitor by decreasing the amount of inhibitor.

[0055] Furthermore, for example, if the amount of regenerated fluid medium introduced into the riser 10 increases, agglomeration is more likely to occur, so the control device 100 increases the amount of inhibitor. This effectively suppresses flow problems caused by agglomeration. Also, if the amount of regenerated fluid medium decreases, the control device 100 can prevent excessive use of the inhibitor by decreasing the amount of inhibitor.

[0056] Furthermore, for example, if the pressure drop in riser 10 increases, it indicates that agglomeration is occurring more frequently, so the control device 100 increases the amount of inhibitor. This effectively suppresses flow problems caused by agglomeration. Also, if the pressure drop decreases, the control device 100 reduces the amount of inhibitor, thereby preventing excessive use of the inhibitor.

[0057] As described above, the combustion system 1000 and the combustion method performed by this embodiment can suppress flow problems due to agglomeration inexpensively and effectively.

[0058] In the above embodiment, agglomeration mainly caused by potassium-mediated SiO2-K2O compounds was described, but other alkali metals such as sodium and calcium can also react with silica and cause agglomeration. Therefore, the control device 100 may further control the amount of inhibitor added based on information about the amount of other alkali metals such as sodium and calcium contained in the fuel introduced into the riser 10.

[0059] Furthermore, in the above embodiment, the fuel and inhibitor are added without mixing, but they may be mixed beforehand before being added.

[0060] Furthermore, in the above embodiment, the amount of inhibitor to be added may be controlled based on information about the amounts of potassium, sodium, and calcium contained in the recycled fluidized medium. This information about the amounts of these elements contained in the recycled fluidized medium may be obtained, for example, by taking a sample of a portion of the recycled fluidized medium and performing a compositional analysis. The information thus obtained may be stored in the control unit 101 by the operator operating the control unit 102 of the control device 100.

[0061] Furthermore, in the above embodiment, the combustion furnace 1 is a circulating fluidized bed type furnace, but it may also be a bubbling fluidized bed (BFB) type furnace.

[0062] Furthermore, further effects and modifications can be readily derived by those skilled in the art. Broader aspects of the present invention are not limited to the specific details and representative embodiments expressed and described above. Accordingly, various modifications are possible without departing from the spirit or scope of the overall concept of the invention as defined by the appended claims and their equivalents. [Explanation of symbols]

[0063] 1: Combustion furnace 10: Liza 11: Diffuser pipe 12: 1st input port 13:Second input port 14: Secondary air inlet 15: Discharge section 20: Downcomer 21: Collection Section 22: Return tube 23: Seal part 30: Piping 40:Fuel injection machine 50: Inhibitor dispenser 60: Circulation line 61: Sieve device 62: Mass measuring device 63:Fluid medium feeding machine 70: Fluid medium feeder 73: Fuel 81,82: Blower 91,93: Pressure sensor 92,94: Temperature sensor 100: Control device 101: Control Unit 102:Operation unit 103: Display section 104: Interface 110: Inhibitor production equipment 1000: Combustion System

Claims

1. A combustion furnace that forms a fluidized bed using a fluidized medium containing silica sand particles and burns a fuel containing alkali metals in the fluidized bed, The combustion furnace includes an inhibitor input section for introducing an inhibitor that suppresses agglomeration of silica sand particles, which is produced from used high-alumina products or scraps generated in the manufacturing process of high-alumina products. A control device that receives information on the operating status of the combustion furnace and controls the amount of the inhibitor to be injected by the inhibitor injection unit based on the input information on the operating status, Equipped with, The inhibitor is composed of particles with a particle size of 1 μm or more and 800 μm or less. Combustion system.

2. The inhibitor is composed of particles with a particle size of 300 μm or less. The combustion system according to claim 1.

3. The information regarding the operating state of the combustion furnace is at least one of the following: the amount of alkali metal contained in the fuel fed into the combustion furnace, the furnace bottom temperature of the combustion furnace, the furnace top temperature of the combustion furnace, the amount of retained material withdrawn from the furnace bottom of the combustion furnace, the amount of new fluidized medium fed into the combustion furnace, the amount of recycled fluidized medium selected from the retained material withdrawn from the furnace bottom of the combustion furnace and fed into the combustion furnace, and the pressure loss in the combustion furnace. The combustion system according to claim 1.

4. In a combustion method using a combustion furnace in which a fluidized bed is formed with a fluidized medium containing silica sand particles and a fuel containing alkali metals is burned in the fluidized bed, The process includes a step of introducing an inhibitor into the combustion furnace, which is made by introducing an inhibitor produced from used high-alumina products or scraps generated during the manufacturing process of high-alumina products, A control step that controls the amount of inhibitor to be introduced in the inhibitor introduction step based on the information on the operating status of the combustion furnace obtained, Equipped with, The inhibitor is composed of particles with a particle size of 1 μm or more and 800 μm or less. Method of combustion.

5. The information regarding the operating state of the combustion furnace is at least one of the following: the amount of alkali metal contained in the fuel fed into the combustion furnace, the furnace bottom temperature of the combustion furnace, the furnace top temperature of the combustion furnace, the amount of retained material withdrawn from the furnace bottom of the combustion furnace, the amount of new fluidized medium fed into the combustion furnace, the amount of recycled fluidized medium selected from the retained material withdrawn from the furnace bottom of the combustion furnace and fed into the combustion furnace, and the pressure loss in the combustion furnace. The combustion method according to claim 4.

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