JPWO2018181366A1 - Boiler system - Google Patents

Abstract

A boiler system is a boiler system including a furnace for burning fuel, and an exhaust gas passage through which exhaust gas generated in the furnace passes and in which a tubular member is disposed.The furnace includes Mg in the furnace. A spray unit for spraying the compound to be contained is provided.

Description

  The present invention relates to a boiler system.

  2. Description of the Related Art As a conventional boiler system, there is known a boiler system including a furnace for burning fuel, and an exhaust gas passage provided downstream of the furnace for passing exhaust gas generated in the furnace. A tubular member is arranged in the exhaust gas passage, and the tubular member heats a fluid such as steam in the tubular member by the heat of the exhaust gas passing through the exhaust gas passage. Here, in recent years, biomass such as construction waste wood and the like, for example, waste tires, waste plastics, RPF, and other wastes are sometimes used as fuel for furnaces. Dust generated by burning such biomass fuel and waste fuel adheres to the tubular member, causing a problem that the tubular member is corroded. With respect to such a problem, in Patent Document 1, corrosion of the tubular member is suppressed by adding an additive to the combustion gas in the flow path of the combustion gas downstream of the furnace. .

Japanese Patent No. 4028801

  However, in the above-described boiler system, the effect of reducing the amount of deposits attached to the surface of the tubular member due to the flow of exhaust gas from the furnace was not sufficient. Therefore, there has been a demand for further reducing the amount of deposits adhering to the tubular member.

  In view of the above, it is an object of the present invention to provide a boiler system capable of suppressing adhesion of deposits to a tubular member arranged in an exhaust gas flow path downstream of a furnace.

  A boiler system according to an embodiment of the present invention is a boiler system including a furnace for burning fuel, and an exhaust gas passage through which exhaust gas generated in the furnace passes and in which a tubular member is arranged. And a spraying section for spraying a compound containing Mg into the furnace.

  In the boiler system according to one aspect of the present invention, the furnace is provided with a spray unit for spraying a compound containing Mg into the furnace. According to such a configuration, the supply of the compound is performed not in the exhaust gas passage where the molten salt adheres to the tubular member, but in a furnace upstream of the exhaust gas passage. Therefore, at a stage before the adhesion of the molten salt to the tubular member, the molten salt can be converted into a compound that is less likely to adhere to the tubular member. The compound supplied to the furnace contains Mg. Further, the low-melting-point molten salt attached to the tubular member of the exhaust gas passage exists as a gas in the combustion gas in the high-temperature furnace. On the other hand, when the compound containing Mg is sprayed into the furnace by the spraying section, the compound is supplied into the furnace in a state substantially close to a gas. Thereby, the chemical reaction between the compound and the molten salt proceeds as well as the reaction between gases. As described above, it is possible to suppress the adhesion of the deposit to the tubular member disposed in the exhaust gas flow path on the downstream side of the furnace.

  In one embodiment, the furnace is provided with a fuel supply unit for supplying fuel into the furnace and a gas outlet for discharging combustion gas generated in the furnace, and the spray unit includes a fuel supply unit and a gas outlet. Compounds may be sprayed in the area between. In a region upstream of the fuel supply unit, which is a stage before the combustion of the fuel occurs, molten salt which causes deposits on the tubular member has not yet been generated. Downstream from the gas outlet, the temperature of the combustion gas decreases. Therefore, the spray unit sprays the compound on the region between the fuel supply unit and the gas outlet, so that the chemical reaction between the compound and the molten salt can be favorably advanced.

  In one embodiment, the spraying unit sprays the compound by supplying the compound into the furnace together with the pumping air (pumping gas) blown into the furnace, and diffuses the compound by adjusting the blowing amount of the pumping air. The position may be controlled. As described above, by using the compressed air, the compound can be sprayed into the furnace in a state where the compound is sufficiently diffused. Further, by adjusting the blowing amount of the compressed air, the diffusion position of the compound can be easily controlled.

  In one mode, the furnace is provided with a secondary combustion air supply unit that supplies secondary combustion air (secondary combustion gas) into the furnace, and the spray unit uses the secondary combustion air as the compressed air. Good. At the place where the secondary combustion air is supplied in the furnace, various substances contained in the combustion gas are in a well-mixed state. Therefore, by spraying the compound together with the secondary combustion air, a chemical reaction between the compound and the molten salt in the combustion gas can be favorably advanced.

  In one mode, the furnace is provided with a secondary combustion air supply unit for supplying secondary combustion air (secondary combustion gas) into the furnace, and the spray unit is provided as compared with the fuel supply unit and the gas outlet. It may be provided at a position near the secondary combustion air supply unit. At the place where the secondary combustion air is supplied in the furnace, various substances contained in the combustion gas are in a well-mixed state. Therefore, by providing the spray section at a position near the secondary combustion air supply section, the compound and the molten salt can be reacted in a well-mixed state. Thereby, the chemical reaction between the molten salt in the combustion gas and the compound can be favorably advanced.

  ADVANTAGE OF THE INVENTION According to this invention, the boiler system which can suppress the adhesion of the deposit to the tubular member arrange | positioned in the exhaust gas flow path downstream of a furnace can be provided.

It is a schematic structure figure of a boiler system concerning an embodiment of the present invention. It is a schematic block diagram of the furnace shown in FIG. It is a schematic structure figure of a furnace concerning a modification. It is a graph which shows the average attached ash weight of the attached matter of the probe after performing a test using each additive. It is a graph which shows the result of having measured the average estimated adhesion ash height of the attachment of the probe after performing a test using each additive. It is a photograph which shows the external appearance of the probe after performing a test using each additive.

  An embodiment of the present invention will be described with reference to the drawings. However, the following embodiment is an exemplification for describing the present invention, and is not intended to limit the present invention to the following contents. In the description, the same reference numerals will be used for the same elements or elements having the same functions, and redundant description will be omitted.

  The configuration of the boiler system 100 according to the present embodiment will be described with reference to FIG. The boiler system 100 is a circulating fluidized bed boiler of an external circulating type (Circuling Fluidized Bed type). The boiler system 100 includes a fluidized bed type furnace 3 having a vertically long cylindrical shape. A fuel supply port 3a for supplying fuel is provided at an intermediate portion of the furnace 3, and a gas outlet 3b for discharging combustion gas is provided at an upper portion. The fuel supplied from the fuel input device 5 to the furnace 3 is supplied to the inside of the furnace 3 through the fuel supply port 3a. The fuel may include biomass, such as construction waste wood, and waste, such as waste tires, waste plastics, and RPF.

  A cyclone 7 functioning as a solid-gas separation device is connected to the gas outlet 3 b of the furnace 3. The outlet 7a of the cyclone 7 is connected to a subsequent gas processing system via a gas line. A return line 9 called a downcomer extends downward from a bottom outlet of the cyclone 7, and a lower end of the return line 9 is connected to a side surface of an intermediate portion of the furnace 3.

  In the furnace 3, the solid containing fuel supplied from the fuel supply port 3 a flows by the air for combustion and flow introduced from the lower air supply line 3 c, and the fuel flows, for example, about 800 to 900. Burns at ℃. The combustion gas generated in the furnace 3 is introduced into the cyclone 7 while accompanied by solid particles. The cyclone 7 separates the solid particles and the gas by the centrifugal action, returns the solid particles separated via the return line 9 to the furnace 3, and sends the combustion gas from which the solid particles have been removed to the gas line 7a through the outlet 7a. To the gas processing system at the subsequent stage.

  In the furnace 3, a solid material called “furnace bed material” is generated and accumulates at the bottom. Sintering and melting and solidification of the bed material caused by concentration of impurities (such as low-melting substances) in the furnace bed material, or It is necessary to suppress malfunction due to incombustible impurities. For this reason, in the furnace 3, the in-furnace bed material is periodically or continuously discharged to the outside from the discharge port 3d at the bottom. The discharged bed material is supplied to the furnace 3 again after removing unsuitable substances such as metal and coarse particles on a circulation line (not shown).

  The gas processing system described above has a gas heat exchange device (exhaust gas passage) 13 connected to the outlet 7a of the cyclone 7 via a gas line, and a gas heat exchange device 13 connected to the outlet 13a of the gas heat exchange device 13 via a gas line. And a collected dust collector 15. The gas heat exchange device 13 is provided with a boiler tube 13b that superheats steam so as to cross the flow path of the exhaust gas. When the high-temperature exhaust gas sent from the cyclone 7 comes into contact with the boiler tube 13b, the heat of the exhaust gas is recovered into the steam in the tube, and the superheated high-temperature steam is passed through the boiler tube (tubular member) 13b for power generation. Sent to turbine. The dust collector 15 removes fine particles such as fly ash still entrained in the combustible gas. As the dust collector 15, for example, a bag filter, an electric dust collector, or the like is employed. The clean gas discharged from the discharge port 15a of the dust collector 15 is discharged to the outside from the chimney 19 via the gas line and the ventilator 17.

  The solid particles generated in the furnace 3 circulate in a circulation system 21 including the furnace 3, the cyclone 7, and the return line 9. In the following description, a fluid of solid particles is referred to as a heat transfer medium. In the circulation system 21, a heat exchange chamber 20 is formed between the return line 9 and the bottom of the furnace 3. A heat transfer medium is stored in the heat exchange chamber 20. Further, a heat exchanger 22 can be provided in the heat exchange chamber 20.

Next, a schematic configuration of the furnace will be described with reference to FIG. The furnace 3 is provided with a spray unit 30 for spraying a compound containing Mg into the furnace 3. As compounds containing Mg, for example, _{MgO · SiO 2, CaO · MgO} · 2SiO 2 etc., or mixtures thereof are employed.

  Here, the fuel contains salts such as Na, K, and Cl, and heavy metals such as lead and zinc. Therefore, the combustion gas generated in the furnace 3 contains a low melting point molten salt such as KCl (melting point 776 ° C.), NaCl (melting point 800 ° C.), for example. Therefore, the molten salt such as KCl affects both the adhesion of ash to the boiler tube 13b and the progress of corrosion. Therefore, the spraying unit 30 sprays the compound containing Mg and reacts the compound with a molten salt such as KCl to convert the compound into gas such as HCl gas and high melting point ash. Thereby, ash adhesion to the boiler tube 13b can be suppressed.

  The particle size of the compound is not particularly limited, but may be, for example, 15 μm or less. When the particle size is 15 μm or less, the reactivity of the compound with KCl or the like in the combustion gas can be improved because the compound particles are small. On the other hand, when the particle size is larger than 15 μm, the handleability of the compound is improved. The amount of the compound added to the furnace 3 may be such that the molar ratio of Mg to Cl contained in the fuel and the compound is 2 to 3 (“molar ratio Mg / Cl = 2 to 3”).

  Here, the term “spray” does not mean simply supplying the compound by dropping it into the internal space of the furnace 3, but supplying the compound with sufficient diffusibility. The molten salt such as KCl in the combustion gas is in a gaseous state. Therefore, the compound can be supplied into the furnace 3 in a state where the compound can be regarded as a gas by spraying the compound with the spraying unit 30 and supplying the compound. Thereby, the reaction between the molten salt and the compound in the combustion gas can be brought into a state close to the reaction between the gases. Here, the advantage of approaching the reaction between gases will be described. For comparison, for example, pouring the particles of the compound into a molten salt in a liquid state (supplying the particles in a dense state instead of supplying the particles in a state of being widely dispersed like a spray) Think about the reaction of things. In this case, the state is close to the reaction between the liquid and the solid (or the reaction between the liquid and the liquid). The liquid is a state in which particles (atoms) constituting a substance are combined with each other to form a dense aggregate. Therefore, in the reaction between the liquids, the aggregate in which the particles are combined comes into contact with another aggregate, and the reaction proceeds at the contacted portion. In the case of such a reaction mode, the reaction does not proceed because the particles existing inside the aggregate away from the interface do not contact each other. Regarding the reaction between the liquid and the solid, the explanation to the same effect is valid because the solid is in a state in which the particles are densely aggregated. On the other hand, the gas is in a state in which particles (atoms) constituting a substance are moving in a space with being separated from each other. Therefore, in the reaction between the gases, the particles are more likely to contact (collide) with each other in the entire space than the reaction between the liquids or the reaction between the liquid and the solid, so that the reaction proceeds more easily. Therefore, by supplying a compound in a state that can be regarded as a gas by spraying the molten salt in a gas state, the reactivity between the molten salt and the compound can be improved.

  When the spray unit 30 is provided on the side wall of the furnace 3 as shown in FIG. 2, a part of the sprayed compound reaches at least the central axis CL of the furnace 3. Part of the compound reaches the central axis CL at a position above the height position of the fuel supply port 3a. Further, since the sprayed compound sufficiently diffuses in the furnace 3, the density in the space of the furnace 3 is lower than when the compound is simply dropped and supplied. Note that the spray unit 30 may not be provided on the side wall of the furnace 3, and the spray unit 30 may be provided on the ceiling of the furnace 3, and the spray unit 30 may spray the compound downward. In this case, the sprayed compound is supplied so as to spread sufficiently in the horizontal direction. For example, the sprayed compound spreads over a range wider than half the width of the furnace 3 in the horizontal direction (indicated by the dimension “R” in FIG. 2). At a position above the height position of the fuel supply port 3a, the compound spreads over a range wider than half the width (dimension R).

  The spraying unit 30 sprays the compound in a region between the fuel supply port 3a, which is a fuel supply unit, and the gas outlet 3b. In addition, regardless of the position where the spray unit 30 is attached, the position where the compound is sprayed may be in the above-described region.

  The spray unit 30 may spray the compound by supplying the compound into the furnace 3 together with the compressed air (pumped gas) blown into the furnace 3. That is, a pumping air supply section (pumping gas supply section) 31 for blowing the pumping air into the furnace 3 is provided, and the compound supply section 32 supplies the compound to a flow path through which the pumping air passes. Thus, the force of the compressed air acts on the compound, so that the compound is sufficiently diffused in the furnace 3. Further, the spray unit 30 can control the diffusion position of the compound by adjusting the blowing amount of the compressed air. For example, when it is desired to spread the compound diffusion position further away from the side wall of the furnace 3, the spray unit 30 sends a control signal to the pumping air supply unit 31 to increase the blowing amount of the pumping air supply unit 31. Alternatively, the spraying unit 30 increases the blowing amount of the compressed air by increasing the opening of a valve (not shown) of the line of the compressed air.

  Further, the furnace 3 is provided with a secondary combustion air supply unit (secondary combustion gas supply unit) 34 for supplying secondary combustion air into the furnace 3. The spray unit 30 is provided at a position closer to the secondary combustion air supply unit 34 than the fuel supply port 3a and the gas outlet 3b, which are fuel supply units. That is, when the spray unit 30 is provided between the secondary combustion air supply unit 34 and the gas outlet 3b, the spray unit 30 is provided at a position near the secondary combustion air supply unit 34. When the spray unit 30 is provided between the secondary combustion air supply unit 34 and the fuel supply port 3a, the spray unit 30 is provided at a position near the secondary combustion air supply unit 34. Thus, the spray unit 30 is provided near the secondary combustion air supply unit 34. At the place where the secondary combustion air is supplied in the furnace 3, the combustion gas is in a sufficiently diffused state. Therefore, by providing the spraying section 30 near the secondary combustion air supply section 34, the compound can be sprayed toward a portion where the combustion gas is diffused, so that the molten salt such as KCl in the combustion gas and the compound can be sprayed. And the reactivity with is improved. The “near” of the secondary combustion air supply unit 34 is defined as “distance = R / 2 (R is a half of the width of the furnace 3 in the horizontal direction) with respect to the secondary combustion air supply unit 34 as a base point. )).

  Alternatively, the spray unit 30 may use secondary combustion air as the compressed air. Specifically, as shown in FIG. 3, the compound supply unit 32 may supply the compound to the flow path of the secondary combustion air supply unit 34. As a result, the spraying unit 30 sprays the compound and simultaneously supplies the secondary combustion air. Alternatively, the flow path of the secondary combustion air may be branched, and the compound supply unit 32 may supply the compound to the branched flow path.

  Here, with reference to FIGS. 4 to 6, a test for confirming the effect when a compound containing Mg is adopted as the compound to be added to the furnace 3 will be described.

In the test, a test device simulating a gas heat exchange device (exhaust gas passage) 13 was used. The test apparatus has a portion where the sample ash is reacted, and a portion where a probe for adhering a deposit is arranged downstream of the portion. The temperature of the reaction section for reacting the sample ash was set to 750 ° C., and the temperature of the place where the probe was disposed was set to 480 ° C. As a sample ash, a ash obtained by adding a predetermined additive to (or not adding) a bio-fired pilot test fly ash to which a KCl reagent had been added was prepared. Specifically, the test (No1) using the sample ash without adding the additive and the test (“mol ratio: S / Cl = 1”) with the sample ash to which (NH ₄ ) ₂ SO ₄ was added ( No. 2) and a test (No. 3) in which “molar ratio: S / Cl = 4” and a test in which the sample ash to which an Al-containing compound was added and “molar ratio: Al / Cl = 0.6” (No4), and a test (No5) in which “molar ratio: Al / Cl = 2.4”, and a sample ash to which a Mg-containing compound was added, wherein “molar ratio: Mg / Cl = 1.2” (No. 6) and a test (No. 7) of “molar ratio: Mg / Cl = 2.5” were performed. In each test, the sample ash was supplied by air to the reaction section of the test apparatus. After heating with the test apparatus was continued for 10 hours, the attached matter attached to the probe was observed.

FIG. 6 shows the appearance of the probe obtained by the above test. The one to which the additive is added shows the appearance of a large amount of the additive. As shown in FIGS. 6 (a) and 6 (b), it was confirmed that many of the non-added and the (NH ₄ ) ₂ SO ₄ -added ones had attached thereto. On the other hand, as shown in FIGS. 6 (c) and 6 (d), it was confirmed that the addition of the Al-containing compound and the addition of the Mg-containing compound suppressed the attachment of deposits to the probe. . FIG. 4 shows the results of measuring the average attached ash weight of the attached matter of the probe, and FIG. 5 shows the results of measuring the average estimated attached ash height of the attached matter of the probe. In FIGS. 4 and 5, the value according to the result of the test (No 1) using the sample ash to which no additive is added is set to “1.0”, and Nos. 2 to 7 indicate the ratios to the No. 1. As shown in FIG. 4 and FIG. 5, as compared with the case where the Al-containing compound was added, the case where the Mg-containing compound was added showed smaller values in both the average attached ash weight and the average estimated attached ash height. Thus, the effect of suppressing deposits was confirmed. In addition, it was confirmed that the effect of suppressing the attached matter was increased by increasing the additive in any of the additives. After the measurement, when the substance adhered to the probe was rubbed with a brush, the substance containing the Al-containing compound and the substance containing the Mg-containing compound were compared with those containing (NH ₄ ) ₂ SO _4. Was able to easily remove the deposits. From this, it is understood that even if the deposits adhere to the tubular member, the deposits can be easily removed when the compound containing Mg is added.

  Next, the operation and effects of the boiler system 100 according to the present embodiment will be described.

  First, as a boiler system according to a comparative example, a boiler system having no spray unit 30 as in the present embodiment will be described. The low-melting molten salt generated in the furnace 3 is contained in the combustion gas and the exhaust gas and reaches the gas heat exchange device (exhaust gas passage) 13 at the subsequent stage together with the combustion ash. The boiler tube (tubular member) 13b provided in the gas heat exchange device 13 functions as a superheater that generates high-temperature and high-pressure steam for use in power generation. Since the surface temperature of the boiler tube 13b is lower than the temperature of the surrounding exhaust gas, a molten salt such as KCl existing as a gas in the exhaust gas condenses as a liquid on the surface of the boiler tube 13b and accumulates together with the combustion ash. In addition, there arises a problem that the boiler tube 13b is corroded.

  On the other hand, in the boiler system 100 according to the present embodiment, the furnace 3 is provided with a spray unit 30 for spraying a compound containing Mg into the furnace 3. According to such a configuration, the supply of the compound is not performed in the gas heat exchange device 13 where the molten salt adheres to the boiler tube 13b, but is performed in the furnace 3 upstream of the gas heat exchange device 13. Will be Therefore, before the molten salt adheres to the boiler tube 13b, the molten salt can be converted into a compound (a compound having a high melting point) that does not easily adhere to the boiler tube 13b. The compound supplied to the furnace 3 contains Mg. The melting point of the compound containing Mg is closer to the temperature in the furnace 3 than other additives (for example, a compound containing Al). Therefore, by spraying such a compound containing Mg into the furnace 3, the chemical reaction between the molten salt in the reaction gas and the compound proceeds favorably in the furnace 3. The low-melting-point molten salt attached to the boiler tube 13 b of the gas heat exchange device 13 exists as a gas in the combustion gas in the furnace 3. On the other hand, when the compound containing Mg is sprayed onto the furnace 3 by the spray unit 30, the compound is supplied into the furnace 3 in a state substantially close to a gas. Thereby, the chemical reaction between the compound and the molten salt proceeds as well as the reaction between gases. As described above, it is possible to suppress the adhesion of the deposit to the boiler tube 13b disposed in the gas heat exchange device 13 on the downstream side of the furnace 3. Further, even if the deposits adhere to the boiler tube 13b, they can be easily peeled off.

  In the boiler system 100, the furnace 3 is provided with a fuel supply port 3 a for supplying fuel into the furnace 3 and a gas outlet 3 b for discharging combustion gas generated in the furnace 3. The compound may be sprayed in a region between the supply port 3a and the gas outlet 3b. In a region upstream of the fuel supply port 3a, which is a fuel supply portion, since the stage before the combustion of the fuel occurs, molten salt causing deposits on the boiler tube 13b has not yet been generated. Downstream from the gas outlet 3b, the temperature of the combustion gas decreases. Therefore, the spraying unit 30 sprays the compound in a region between the fuel supply port 3a and the gas outlet 3b, so that the chemical reaction between the compound and the molten salt can be favorably advanced.

  In the boiler system 100, the spraying unit 30 sprays the compound by supplying the compound into the furnace 3 together with the compressed air blown into the furnace 3, and adjusts the blowing amount of the compressed air to diffuse the compound. The position may be controlled. As described above, by using the compressed air, the compound can be sprayed into the furnace 3 in a state where the compound is sufficiently diffused. Further, by adjusting the blowing amount of the compressed air, the diffusion position of the compound can be easily controlled.

  In the boiler system 100, the furnace 3 is provided with a secondary combustion air supply unit 36 that supplies secondary combustion air into the furnace 3, and the spray unit 30 may use the secondary combustion air as compressed air. . In the place where the secondary combustion air is supplied in the furnace 3, various substances contained in the combustion gas are in a well-mixed state. Therefore, by spraying the compound together with the secondary combustion air, a chemical reaction between the compound and the molten salt in the combustion gas can be favorably advanced.

  In the boiler system 100, the furnace 3 is provided with a secondary combustion air supply unit 36 for supplying secondary combustion air into the furnace 3, and the spray unit 30 includes a fuel supply port 3a serving as a fuel supply unit and a gas outlet. 3b, it may be provided at a position closer to the secondary combustion air supply unit 34. In the place where the secondary combustion air is supplied in the furnace 3, various substances contained in the combustion gas are in a well-mixed state. Therefore, by providing the spray unit 30 at a position near the secondary combustion air supply unit 36, the compound and the molten salt can be reacted in a well-mixed state. Thereby, the chemical reaction between the molten salt in the combustion gas and the compound can be favorably advanced.

  A method for preventing corrosion of a boiler system is a method for preventing corrosion of a boiler system including a furnace for burning fuel, and an exhaust gas passage through which exhaust gas generated in the furnace passes and in which a tubular member is disposed. The method for preventing corrosion of a boiler system in which a compound containing Mg is sprayed.

  The present invention is not limited to the above embodiment.

  The overall configuration of the boiler system according to the above-described embodiment is merely an example, and may be appropriately changed within the scope of the present invention. Further, the configuration of the furnace is not limited to the above-described embodiment, and the shape and the like may be appropriately changed.

  In the boiler system according to the above-described embodiment, the compound is sprayed using the compressed air, but instead, a method in which the fuel and the compound are mixed in advance and the fuel is simultaneously supplied from the fuel input device to the furnace may be employed. Good.

  Reference numeral 3: furnace, 3a: fuel supply port (fuel supply section), 3b: gas outlet, 13: gas heat exchanger (exhaust gas passage), 13b: boiler tube (tubular member), 30: spray section, 34: secondary combustion Air supply unit, 100 ... boiler system.

Claims (5)

A furnace for burning fuel,
Exhaust gas generated in the furnace passes through, an exhaust gas passage in which a tubular member is disposed, a boiler system,
A boiler system, wherein the furnace is provided with a spray unit for spraying a compound containing Mg into the furnace. The furnace is provided with a fuel supply unit that supplies the fuel into the furnace, and a gas outlet that discharges combustion gas generated in the furnace,
The boiler system according to claim 1, wherein the spraying unit sprays the compound in a region between the fuel supply unit and the gas outlet. The spraying unit,
By supplying the compound into the furnace together with the pumping gas blown into the furnace, spraying the compound,
The boiler system according to claim 1, wherein a diffusion position of the compound is controlled by adjusting a blowing amount of the pumping gas. The furnace is provided with a secondary combustion gas supply unit that supplies a secondary combustion gas into the furnace,
The boiler system according to claim 3, wherein the spraying unit uses the secondary combustion gas as the pumping gas. The furnace is provided with a secondary combustion gas supply unit that supplies a secondary combustion gas into the furnace,
3. The boiler system according to claim 2, wherein the spray unit is provided at a position closer to the secondary combustion gas supply unit than the fuel supply unit and the gas outlet. 4.