Combustion system for alkaline metal containing fuel and combustion method for alkaline metal containing fuel

Abstract

To suppress poor fluidization due to agglomeration in a fluid medium that forms a fluidized bed within a combustion furnace.SOLUTION: A combustion system that uses a combustion furnace forming a fluidized bed by using a fluid medium and burning fuel containing alkaline metal in the fluidized bed includes: a sieve device that separates a fluid medium discharged from the combustion furnace into a fluid medium of which particle size is equal to or lower than a predetermined particle size value and a fluid medium of which particle size exceeds the predetermined particle size value; an analyzer that measures a concentration of alkaline metal included in the fluid medium separated by the sieve device and having the particle size equal to or lower than the predetermined particle size value through a fluorescence X-ray analysis; and a control device that controls an amount of the fluid medium to be discharged from the combustion furnace and an amount of the fluid medium to be supplied to the combustion furnace in accordance with the concentration.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a combustion system for an alkali metal-containing fuel and a method for burning an alkali metal-containing fuel.

Background Art

[0002] There is a method using a fluidized bed furnace as a method for generating electricity using biomass as fuel. A fluidized bed furnace forms a fluidized bed in which a high-temperature fluid medium is fluidized by the fluidizing air that blows up, and burns the fuel supplied into the furnace in the fluidized bed. As biomass as fuel, for example, biomass derived from plants and inexpensive like palm coconut empty fruit bunch (EFB) has attracted attention. However, when generating electricity by burning palm coconut empty fruit bunch in a fluidized bed furnace, the following problems occur.

[0003] Palm coconut empty fruit bunch contains a large amount of potassium which is an alkali metal. Although silica sand is used as the fluid medium of the fluidized bed furnace, the gaseous potassium released from palm coconut empty fruit bunch in the fluidized bed furnace reacts with silicon oxide of the silica sand particles, and a SiO2-K2O compound is formed on the surface 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 and an adhesive layer is formed on the surface of the silica sand particles. When this adhesive layer is formed, several silica sand particles fuse together, and when agglomeration and lumping (agglomeration) of silica sand occur, the silica sand does not flow, and the normal operation of the fluidized bed furnace is hindered. Therefore, as inventions for solving such problems, there are, for example, the inventions disclosed in Patent Documents 1 and 2.

[0004] The invention disclosed in Patent Document 1 is such that the fluid medium consists of particulate minerals and / or particulate slag, and the quartz content is 14% by mass or less. Since the amount of quartz contained in the fluid medium is 14% by mass or less, even if the quartz in the fluid medium reacts with the alkali metal component in the fuel to form an adhesive layer on the particle surface, agglomeration and lumping of the fluid medium do not occur or occur only slightly, and the fluidized bed can maintain good fluidity.

[0005] The invention disclosed in Patent Document 2 detects the blowing-up situation of the fluidized medium near the outlet of the fluidized bed furnace with a laser monitoring device while controlling the fluidizing gas velocity inside the fluidized bed furnace to be near 4 m / s, and feeds back the amount of incineration air corresponding to the blowing-up state to the supply side of the combustion air. By increasing the fluidizing gas velocity in the fluidized bed furnace to about 4 m / s, the limit salt accumulation amount in the fluidized medium can be increased, thereby increasing the amount of waste that can be processed without causing poor fluidization in the fluidized bed.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] In the invention disclosed in Patent Document 1, examples of the fluidized medium include garnet, ilmenite, kanran stone, ferronickel slag, etc. However, as described in Table 2 of Patent Document 1, these are more expensive than inexpensive and general-purpose silica sand, and it costs to replace the fluidized medium. In the invention of Patent Document 2, although the limit salt accumulation amount in the fluidized medium can be increased, since agglomeration occurs due to a slight change in the alkali metal, there is a risk that agglomeration will occur suddenly and lead to poor fluidization when the limit salt accumulation amount is exceeded.

[0008] The present invention has been made in view of the above, and an object thereof is to suppress poor fluidization due to agglomeration in a fluidized medium that forms a fluidized bed in a combustion furnace.

Means for Solving the Problems

[0009] A combustion system for an alkali metal-containing fuel according to an aspect of the present invention is a combustion system using a combustion furnace that forms a fluidized bed with a fluid medium and burns a fuel containing an alkali metal in the fluidized bed. The combustion system includes a screening device that separates the fluid medium discharged from the combustion furnace into a fluid medium having a particle size equal to or less than a predetermined particle size value and a fluid medium having a particle size exceeding the predetermined particle size value, an analyzer that measures the concentration of the alkali metal contained in the fluid medium having a particle size equal to or less than the predetermined particle size value separated by the screening device by X-ray fluorescence analysis, and a controller that controls the amount of the fluid medium discharged from the combustion furnace and the amount of the fluid medium supplied to the combustion furnace according to the concentration.

[0010] Further, in the combustion system for an alkali metal-containing fuel according to the present invention, a measuring device measures the particle size value of the mass of the fluid medium having a particle size exceeding the predetermined particle size value separated by the screening device and the weight per unit time of the fluid medium having a particle size exceeding the predetermined particle size value separated and conveyed by the screening device. The controller may control the amount of the fluid medium discharged from the combustion furnace and the amount of the fluid medium supplied to the combustion furnace according to the particle size value measured by the measuring device and the weight measured by the measuring device.

[0011] Further, in the combustion system for an alkali metal-containing fuel according to the present invention, the controller may control the amount of the fuel supplied to the combustion furnace according to the concentration.

[0012] Further, in a combustion system of an alkali metal-containing fuel according to the present invention, in a combustion system using a combustion furnace that forms a fluidized bed with a fluid medium and burns a fuel containing an alkali metal in the fluidized bed, a sieve device that separates the fluid medium discharged from the combustion furnace into a fluid medium having a particle size value equal to or less than a predetermined particle size value and a fluid medium having a particle size value exceeding the predetermined particle size value; a measuring device that measures the particle size value of the fluid medium having a particle size value exceeding the predetermined particle size value separated by the sieve device and the weight per unit time of the fluid medium having a particle size value exceeding the predetermined particle size value separated and conveyed by the sieve device; and a control device that controls the amount of the fluid medium discharged from the combustion furnace and the amount of the fluid medium supplied to the combustion furnace according to the particle size value measured by the measuring device and the weight measured by the measuring device.

[0013] A combustion method of an alkali metal-containing fuel according to one aspect of the present invention is a combustion method using a combustion furnace that forms a fluidized bed with a fluid medium in a furnace and burns a fuel containing an alkali metal in the fluidized bed, the method comprising: a separation step of separating the fluid medium discharged from the combustion furnace into a fluid medium having a particle size value equal to or less than a predetermined particle size value and a fluid medium having a particle size value exceeding the predetermined particle size value; an analysis step of measuring the concentration of the alkali metal contained in the fluid medium having a particle size value equal to or less than the predetermined particle size value separated in the separation step by fluorescent X-ray analysis; and a control step of controlling the amount of the fluid medium discharged from the combustion furnace and the amount of the fluid medium supplied to the combustion furnace according to the concentration.

[0014] Further, a method for burning an alkali metal-containing fuel according to an aspect of the present invention is a combustion method using a combustion furnace that forms a fluidized bed with a fluid medium in the furnace and burns a fuel containing an alkali metal in the fluidized bed. The method includes a separation step of separating the fluid medium discharged from the combustion furnace into a fluid medium having a particle size equal to or less than a predetermined particle size value and a fluid medium having a particle size exceeding the predetermined particle size value, a measurement step of measuring the particle size value of the fluid medium having a particle size exceeding the predetermined particle size value separated in the separation step and the weight per unit time of the fluid medium having a particle size exceeding the predetermined particle size value separated and conveyed in the separation step, and a control step of controlling the amount of the fluid medium discharged from the combustion furnace and the amount of the fluid medium supplied to the combustion furnace according to the particle size value measured in the measurement step and the weight measured in the measurement step.

Advantages of the Invention

[0015] According to the present invention, there is an effect that it is possible to suppress poor fluidization due to agglomeration in the fluid medium that forms a fluidized bed in the combustion furnace.

Brief Description of the Drawings

[0016]

Figure 1

Modes for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that the present invention is not limited by the embodiments described below. Also, the drawings are schematic, and it is necessary to note that the dimensional relationships of each element may be different from the actual ones.

[0018] [Embodiment] FIG. 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) furnace. The combustion furnace 1 is a furnace that forms a fluidized bed by flowing a fluid medium 81 inside and burns the fuel 73 supplied into the combustion furnace 1 in the fluidized bed. The combustion furnace 1 mainly includes a riser 10 as a furnace body and a downcomer 20 that collects a part of the fluid medium 81 and returns it to the riser 10.

[0019] The riser 10 is provided with a diffuser pipe 11 at the lower part for blowing the primary air supplied from the blower 91 upward. Further, on the side wall of the lower part of the riser 10, there are provided, in order from below, a fluid medium supply port 12 for supplying the fluid medium 81 into the riser 10 above the diffuser pipe 11, a fuel supply port 13 for supplying the fuel 73 into the riser 10, and a secondary air blowing port 14 for blowing the secondary air supplied from the blower 92 into the riser 10. Also, at the bottom of the riser 10, a discharge part 15 for discharging the fluid medium 81 and furnace bottom ash inside the riser 10 is provided.

[0020] The downcomer 20 is connected to the upper part of the riser 10 by a pipe 30. The downcomer 20 has a collection part 21 for collecting the fluid medium 81 sent together with the exhaust gas from the riser 10, a return pipe 22 for returning the fluid medium 81 collected by the collection part 21 to the lower part of the riser 10, and a seal part 23 for preventing the gas from the riser 10 from rising inside the collection part 21.

[0021] Near the combustion furnace 1, a circulation line 40 is provided for regenerating the fluid medium 81 discharged from the discharge part 15 and returning it to the combustion furnace 1. In the circulation line 40, a sieve device 41, a polishing device 42, a sorting device 43, and a fluid medium feeder 44 are arranged in order from the discharge part 15.

[0022] The screening device 41 receives the fluid medium 81 and the bottom ash discharged from the discharge section 15, and sends out the fluid medium 81 with a particle size below a predetermined size that has passed through the sieve to the polishing device 42. The particle size of the fluid medium 81 passing through the sieve is, for example, 1 mm or less. Further, the screening device 41 sends out the agglomerated mass of the fluid medium 81 having a diameter larger than the predetermined size due to agglomeration that does not pass through the sieve, and the incombustibles generated after the combustion of the fuel 73, to the waste line 50 for discarding the fluid medium 81. The step of separating the fluid medium 81 with a particle size below a predetermined size from the fluid medium with a particle size exceeding the predetermined size in the screening device 41 is an example of a separation step.

[0023] The polishing device 42 polishes the fluid medium 81 sent from the screening device 41 and removes the alkali metal component adhering to the fluid medium 81. There is no limitation on the polishing method used in the polishing device 42. For example, a self-crushing method, a shear grinding method, a blasting method, etc. are applicable. The fluid medium 81 from which the alkali metal component has been removed by the polishing device 42 and the alkali metal component removed from the fluid medium 81 are sent to the sorting device 43.

[0024] The sorting device 43 sorts the fluid medium 81 from the mixture of the alkali metal component and the fluid medium 81 sent from the polishing device 42. There is no limitation on the sorting method used in the sorting device 43. For example, a pneumatic sorting method, a specific gravity sorting method, etc. are applicable. The fluid medium 81 sorted by the sorting device 43 is sent to the fluid medium feeder 44.

[0025] The fluid medium feeder 44 stores the fluid medium 81 sent from the sorting device 43 and supplies the fluid medium 81 into the riser 10. In the present embodiment, the fluid medium 81 is, for example, silica sand. A part of the fluid medium 81 stored in the fluid medium feeder 44 is discarded from the lower part of the fluid medium feeder 44. In the fluid medium feeder 44, since a part of the stored fluid medium 81 is discarded, new fluid medium 81 is replenished to make up for the discarded portion. The fluid medium 81 stored in the fluid medium feeder 44 is sent to the fluid medium supply port 12 and supplied into the riser 10 from the fluid medium supply port 12. Note that a part of the fluid medium 81 may be discarded by the polishing device 42 or the sorting device 43.

[0026] Also, the fluid medium 81 sent from the sieving device 41 to the polishing device 42 is extracted at a predetermined cycle and sent to the analyzer 52. The analyzer 52 is a device that analyzes the fluid medium 81 extracted between the sieving device 41 and the polishing device 42 by X-ray fluorescence analysis and measures the concentration of the alkali metal component contained in the fluid medium 81. The analyzer 52 transmits the measurement result of the measured concentration of the alkali metal component to the control device 51. The step of measuring the concentration of the alkali metal component contained in the fluid medium 81 with the analyzer 52 is an example of the analysis step.

[0027] Also, the particle size and weight of the fluid medium 81 sent from the sieving device 41 to the waste line 50 are measured by the measuring device 53. Specifically, the measuring device 53 takes a picture of the fluid medium 81 in the waste line 50 with the camera 53a, recognizes the plurality of agglomerated fluid media 81 by image recognition technology, and takes the average value of the diagonal lengths of the bounding boxes surrounding the recognized plurality of agglomerated fluid media 81 as the particle size value of the agglomerated fluid medium 81. In addition, a load cell 53b is provided on the belt conveyor that conveys the fluid medium 81 in the waste line 50, and the weight of the fluid medium 81 being conveyed in the waste line 50 is measured by this load cell 53b. The measuring device 53 acquires the measurement result of the load cell 53b and measures the weight of the fluid medium 81 conveyed per unit time. The measuring device 53 transmits the measured particle size value and weight to the control device 51. The step of measuring the particle size value of the agglomerated fluid medium 81 and the weight of the fluid medium 81 exceeding a predetermined particle size conveyed per unit time is an example of the measurement step.

[0028] The control device 51 is a device that controls the discharge unit 15 and the fluid medium supply machine 44. The control device 51 controls the discharge unit 15 and the fluid medium supply machine 44 based on the measurement result of the concentration of the alkali metal component transmitted from the analyzer 52 and the particle size value and weight sent from the measuring device 53. The step of the control device 51 controlling the discharge unit 15 and the fluid medium supply machine 44 is an example of the control step.

[0029] The fuel supply device 61 is a device that sends the fuel 73 to be burned in the combustion furnace 1 to the fuel supply port 13. The fuel supply device 61 sends the fuel 73 obtained by mixing the first fuel 71 and the second fuel 72 to the fuel supply port 13. The first fuel 71 is a fuel with a high content of alkali metal components, such as palm coconut empty fruit bunches. The second fuel 72 is a fuel with a lower content of alkali metal components compared to the first fuel 71, such as wood chips.

[0030] Next, the operation of the combustion system 1000 will be described. By blowing the primary air sent from the blower 91 into the riser 10 from the air diffuser pipe 11 and blowing the secondary air sent from the blower 92 into the riser 10 from the secondary air injection port 14, a fluidized bed in which the fluid medium 81 is fluidized is formed in the riser 10.

[0031] Also, the fuel 73 is supplied into the riser 10 from the fuel supply port 13. Regarding the fuel 73 supplied from the fuel supply port 13, it is preferable that the proportion of the first fuel 71 is larger from the perspective of operating cost. The fuel 73 supplied into the riser 10 burns in the fluidized bed.

[0032] Specifically, the fluid medium 81 becomes fluidized by the primary air blown from the air diffuser pipe 11, and a dense layer where the fluid medium 81 is dense is formed at the lower part in the riser 10. In this dense layer, the drying of the fuel 73 and the release of volatile components are promoted by the high heat capacity and stirring effect. Also, at the upper part in the riser 10, the fluid medium 81 is blown up by the blowing of the primary air and the secondary air, and a dilute layer where the fluid medium 81 is dilute is formed. In this dilute layer, the combustion of the fuel 73 is carried out by the heat capacity and stirring effect possessed by the fluid medium 81. That is, the combustion furnace 1 forms a fluidized bed composed of a dense layer and a dilute layer in the riser 10 to prevent the generation of char, which is unburned carbon, and efficiently burn the fuel 73, which is palm coconut empty fruit bunches. Note that the combustion region in the riser 10 is maintained at about 850 to 900 °C.

[0033] The exhaust gas generated by the combustion of fuel 73 in riser 10 is supplied to the collection section 21 of downcomer 20 via pipe 30. Also, a part of the fluid medium 81 is also sent from riser 10 to collection section 21 together with the exhaust gas. In collection section 21, the fluid medium 81, ash with a relatively large particle size, etc. are recovered and returned to the lower part of riser 10 through seal section 23 and return pipe 22. Further, the exhaust gas, ash with a relatively small particle size, etc. are discharged from the top of downcomer 20, sent to exhaust gas treatment equipment via a superheater (not shown), the steam is superheated in the superheater, and after dust removal in the exhaust gas treatment equipment, it is discharged to the outside from a chimney (not shown).

[0034] In this embodiment, the first fuel 71 (palm coconut empty fruit bunch) contained in the fuel 73 burned in riser 10 releases gaseous potassium, which is an alkali metal component. This gaseous potassium component reacts with silicon dioxide of the silica sand particles that are the fluid medium 81, and an SiO2-K2O compound is formed on the surface of the silica sand particles. This SiO2-K2O compound melts to form an adhesive layer on the surface of the silica sand particles. Due to this adhesive layer, several fluid medium 81 particles fuse together and fall to the bottom of riser 10. The fused and fallen fluid medium 81 further fuses to form a lump. The fluid medium 81 containing this lump and the incombustibles remaining after the combustion of fuel 73 are discharged from discharge section 15 at a predetermined amount per unit time and sent to screening device 41.

[0035] Screening device 41 to which the fluid medium 81 is sent sends out the fluid medium 81 with a particle size below a predetermined size that has passed through the screen to polishing device 42. Also, screening device 41 sends out the incombustibles after combustion and the lumps of fluid medium 81 with a particle size exceeding the predetermined size to waste line 50. In polishing device 42, the fluid medium 81 is polished, and the alkali metal component adhering as an adhesive layer on the surface of the fluid medium 81 is removed from the surface of the fluid medium 81. The alkali metal component removed from the fluid medium 81 in polishing device 42 and the fluid medium 81 from which the alkali metal component has been removed in polishing device 42 are sent to sorting device 43.

[0036] In the sorting device 43, the fluid medium 81 is sorted and the alkali metal component is separated, and the sorted fluid medium 81 is sent to the fluid medium feeder 44. In the fluid medium feeder 44, a part of the fluid medium 81 is discarded from the lower part of the fluid medium feeder 44, and new fluid medium 81 is replenished from the upper part.

[0037] In addition, the fluid medium 81 sent from the screening device 41 to the polishing device 42 is extracted at a predetermined cycle and sent to the analyzer 52. The analyzer 52 analyzes the fluid medium 81 extracted between the screening device 41 and the polishing device 42 by fluorescent X-ray analysis and measures the concentration of the alkali metal component contained in the fluid medium 81. Here, since the fluid medium 81 is separated by the screening device 41 and its diameter is made uniform, the concentration of the alkali metal component on the surface of the silica sand particles, which is the fluid medium 81, can be accurately measured. The measured concentration is transmitted to the control device 51.

[0038] Also, for the fluid medium 81 sent from the screening device 41 to the waste line 50, the particle size value of the agglomerated fluid medium 81 and the weight of the fluid medium 81 conveyed per unit time are measured by the camera 53a, the load cell 53b, and the measuring device 53. The measuring device 53 transmits the measured particle size value and the weight of the fluid medium 81 conveyed per unit time to the control device 51.

[0039] The control device 51 controls the fluid medium feeder 44, and according to the amount of the fluid medium 81 discharged per unit time from the discharge part 15, it sends the fluid medium 81 stored in the fluid medium feeder 44 to the fluid medium supply port 12 and supplies a predetermined amount of the fluid medium 81 into the riser 10.

[0040] In addition, the control device 51 controls the discharge part 15 and the fluid medium feeder 44 based on the measurement result of the concentration of the alkali metal component contained in the fluid medium 81 transmitted from the analyzer 52 and the particle size value and the weight transmitted from the measuring device 53, thereby controlling the discharge amount of the fluid medium 81 from the riser 10 and the supply amount of the fluid medium 81 from the fluid medium feeder 44 to the riser 10.

[0041] For example, when the concentration of the alkali metal contained in the fluid medium 81 is equal to or higher than a predetermined threshold value, the measured particle size value is equal to or higher than a predetermined threshold value, and the measured weight is equal to or higher than a predetermined threshold value, the control device 51 controls the discharge unit 15 to increase the amount of the fluid medium 81 discharged from the discharge unit 15 per unit time from a predetermined amount, and controls the fluid medium supply device 44 to increase the amount of the fluid medium 81 supplied from the fluid medium supply device 44 into the riser 10 per unit time from a predetermined amount. Thereby, the mass of the fluid medium 81 can be discharged, and the poor flow of the fluid medium 81 can be suppressed.

[0042] Further, for example, when the concentration of the alkali metal contained in the fluid medium 81 is less than a predetermined threshold value, the measured particle size value is less than a predetermined threshold value, and the measured weight is less than a predetermined threshold value, the control device 51 controls the discharge unit 15 to return the amount of the fluid medium 81 discharged from the discharge unit 15 to a predetermined amount, and controls the fluid medium supply device 44 to return the amount of the fluid medium 81 supplied from the fluid medium supply device 44 to the riser 10 to a predetermined amount.

[0043] Note that the control device 51 may control the supply amount of the first fuel 71 and the supply amount of the second fuel 72 based on the measured alkali metal concentration, the measured particle size value, and the measured weight. For example, when the alkali metal concentration contained in the fluid medium 81 is equal to or higher than a predetermined threshold value, the particle size value measured by the measuring device 53 is equal to or higher than a predetermined threshold value, and the weight measured by the measuring device 53 is equal to or higher than a predetermined threshold value, the fuel supply machine 61 may be controlled such that the ratio of the first fuel 71 in the fuel 73 is reduced and the ratio of the second fuel 72 increases. Further, when the alkali metal concentration contained in the fluid medium 81 is less than a predetermined threshold value, the particle size value measured by the measuring device 53 is less than a predetermined threshold value, and the weight measured by the measuring device 53 is less than a predetermined threshold value, the fuel supply machine 61 may be controlled such that the ratio of the first fuel 71 in the fuel 73 is returned to a predetermined ratio. According to this control, when the alkali metal concentration increases, the ratio of the first fuel 71 containing the alkali metal decreases, so that the occurrence of agglomeration can be suppressed.

[0044] [Modification Example] As described above, the embodiments of the present invention have been described. However, the present invention is not limited to the above-described embodiments and can be implemented in various other forms. For example, the present invention may be implemented by modifying the above-described embodiments as follows. Note that the above-described embodiments and the following modification examples may be combined with each other. The present invention also includes those configured by appropriately combining the components of the above-described embodiments and each modification example. Further, additional effects and modification examples can be easily derived by those skilled in the art. Therefore, a broader aspect of the present invention is not limited to the above-described embodiments and modification examples, and various changes are possible.

[0045] In the above-described embodiment, the combustion furnace 1 is a circulating fluidized bed type furnace, but may be a bubbling fluidized bed (BFB) type furnace.

[0046] In the present invention, in order to suppress the decrease in the temperature inside the riser 10 due to the supply of the new fluid medium 81 into the riser 10, the supply amount of the fuel 73 into the riser 10 may be increased according to the supply amount of the fluid medium 81. In this case, in order to suppress the occurrence of agglomeration, the ratio of the second fuel 72 may be increased. Further, in order to suppress the decrease in the temperature inside the riser 10 due to the increase in the supply amount of the fluid medium 81, kerosene or heavy oil may be supplied as auxiliary fuel.

[0047] In the present invention, the fuel 73 may include the shells of the seeds of the oil palm (PKS: Palm Kernel Shell).

[0048] In the present invention, the temperature inside the riser 10 may be measured, and the amount of the fluid medium 81 discharged from the discharge part 15 and the amount of the fluid medium 81 supplied from the fluid medium supply machine 44 to the riser 10 may be controlled according to the measured temperature.

[0049] When the concentration of the alkali metal contained in the fluid medium 81 is equal to or higher than a predetermined threshold value without using the particle size value and the weight transmitted from the measuring device 53, the control device 51 controls the discharge part 15 to increase the amount of the fluid medium 81 discharged from the discharge part 15 per unit time from a predetermined amount, and controls the fluid medium supply machine 44 to increase the amount of the fluid medium 81 supplied from the fluid medium supply machine 44 into the riser 10 per unit time from a predetermined amount.

[0050] When the particle size value transmitted from the measuring device 53 is equal to or higher than a predetermined threshold value and the weight transmitted from the measuring device 53 is equal to or higher than a predetermined threshold value without using the alkali metal concentration transmitted from the analyzing device 52, the control device 51 controls the discharge part 15 to increase the amount of the fluid medium 81 discharged from the discharge part 15 per unit time from a predetermined amount, and controls the fluid medium supply machine 44 to increase the amount of the fluid medium 81 supplied from the fluid medium supply machine 44 into the riser 10 per unit time from a predetermined amount.

Explanation of Signs

[0051] 1 Combustion furnace 15 Discharge section 40 Circulation line 41 Sieve device 42 Grinding device 43 Sorting device 44 Fluid medium feeder 50 Waste line 51 Control device 52 Analyzer 53 Measuring device 53a Camera 53b Load cell 61 Fuel feeder 71 First fuel 72 Second fuel 1000 Combustion system

Claims

1. In a combustion system using a combustion furnace that forms a fluidized bed with a fluid medium and burns a fuel containing an alkali metal in the fluidized bed, a screening device that separates the fluid medium discharged from the combustion furnace into a fluid medium having a particle size equal to or less than a predetermined particle size value and a fluid medium having a particle size exceeding the predetermined particle size value; an analyzer that measures the concentration of the alkali metal contained in the fluid medium having a particle size equal to or less than the predetermined particle size value separated by the screening device by X-ray fluorescence analysis; a control device that controls the amount of the fluid medium discharged from the combustion furnace and the amount of the fluid medium supplied to the combustion furnace according to the concentration; A combustion system for an alkali metal-containing fuel comprising:

2. a measuring device that measures the particle size value of the mass of the fluid medium having a particle size exceeding the predetermined particle size value separated by the screening device and the weight per unit time of the fluid medium having a particle size exceeding the predetermined particle size value separated and conveyed by the screening device; The control device controls the amount of the fluid medium discharged from the combustion furnace and the amount of the fluid medium supplied to the combustion furnace according to the particle size value measured by the measuring device and the weight measured by the measuring device. The combustion system for an alkali metal-containing fuel according to claim 1.

3. The control device controls the amount of the fuel supplied to the combustion furnace according to the concentration. The combustion system for an alkali metal-containing fuel according to claim 1 or claim 2.

4. In a combustion system using a combustion furnace that forms a fluidized bed with a fluid medium and burns a fuel containing an alkali metal in the fluidized bed, a screening device that separates the fluid medium discharged from the combustion furnace into a fluid medium having a particle size equal to or less than a predetermined particle size value and a fluid medium having a particle size exceeding the predetermined particle size value; a measuring device that measures the particle size value of the fluid medium having a particle size exceeding the predetermined particle size value separated by the screening device and the weight per unit time of the fluid medium having a particle size exceeding the predetermined particle size value separated and conveyed by the screening device; a control device that controls the amount of the fluid medium discharged from the combustion furnace and the amount of the fluid medium supplied to the combustion furnace according to the particle size value measured by the measuring device and the weight measured by the measuring device; A combustion system for an alkali metal-containing fuel comprising:

5. In a combustion method using a combustion furnace that forms a fluidized bed with a fluid medium in the furnace and burns a fuel containing an alkali metal in the fluidized bed, A separation step of separating the fluidized medium discharged from the combustion furnace into a fluidized medium having a particle size equal to or less than a predetermined particle size value and a fluidized medium having a particle size exceeding the predetermined particle size value; An analysis step of measuring the concentration of the alkali metal contained in the fluidized medium having a particle size equal to or less than the predetermined particle size value separated in the separation step by X-ray fluorescence analysis; A control step of controlling the amount of the fluidized medium discharged from the combustion furnace and the amount of the fluidized medium supplied to the combustion furnace according to the concentration; A combustion method of an alkali metal-containing fuel comprising the above.

6. In a combustion method using a combustion furnace in which a fluidized bed is formed by a fluidized medium in the furnace and a fuel containing an alkali metal is burned in the fluidized bed, A separation step of separating the fluidized medium discharged from the combustion furnace into a fluidized medium having a particle size equal to or less than a predetermined particle size value and a fluidized medium having a particle size exceeding the predetermined particle size value; A measurement step of measuring the particle size value of the fluidized medium having a particle size exceeding the predetermined particle size value separated in the separation step and the weight per unit time of the fluidized medium having a particle size exceeding the predetermined particle size value separated and conveyed in the separation step; A control step of controlling the amount of the fluidized medium discharged from the combustion furnace and the amount of the fluidized medium supplied to the combustion furnace according to the particle size value measured in the measurement step and the weight measured in the measurement step; A combustion method of an alkali metal-containing fuel comprising the above.

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