JP2000024453A - Treatment of stack gas of fluidized-bed boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of realizing the desulfurization of a stack gas generated in a fluidized-bed boiler with simpler equipment constitution. SOLUTION: This method for treating a stack gas is provided with a desulfurization process in a fluidized-bed boiler in which sulfur dioxide in the stack gas generated by fluidizing a desulfurizing agent and a fuel grain in the fluidized-bed boiler 1 are absorbed by the desulfurizing agent, a conversion process in which the sulfur dioxide remaining in the stack gas A2 discharged from the boiler 1 and passed through a gas turbine 3 is converted to sulfur trioxide by a converter 10 packed with a conversion catalyst, a deposition process in which the sulfur trioxide in the stack gas A3 generated in the conversion process and contg. the sulfur trioxide is reacted with injected ammonia B to deposit ammonium sulfate and a dusk removing process in which a solid component in the stack gas A4 contg. the deposited ammonium sulfate generated in the deposition process is removed by a dust removing means 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technology that enables an effective and simple structure to desulfurize flue gas generated in a fluidized-bed boiler.

[0002]

2. Description of the Related Art In recent years, due to the depletion of petroleum resources and soaring prices, the development of technologies for highly efficient utilization of coal and the like has been promoted.
The combined power generation system according to C) is receiving attention. This combined power generation system can significantly improve the power generation efficiency beyond the limits of ordinary coal-fired power generation, and also has the features of a fluidized-bed boiler that can desulfurize the furnace and emit sulfur oxides and nitrogen oxides. The advantage is that the amount is relatively small. For this reason, practical use is urgently required for effective use of resources and measures for preserving the global environment.

However, even in a power generation system using a fluidized bed boiler as described above, which is expected to spread in the future, sulfur oxides and nitrogen oxides remaining in flue gas discharged from the boiler are removed. It is considered necessary to have flue gas treatment technology to release it into the atmosphere as cleaner flue gas, and emission regulations such as sulfur oxides may be further strengthened in each country in the future due to problems such as acid rain. Considering the nature,
It can be said that it is becoming more important. Hereinafter, as a flue gas treatment technology of such a fluidized bed boiler, currently known,
Alternatively, the proposed technology will be described.

[0004] First, as a desulfurization treatment technique for removing sulfur oxides such as sulfur dioxide (sulfur dioxide) from flue gas generated in a fluidized-bed boiler, the above-mentioned technique called in-furnace desulfurization is known. This utilizes a characteristic of a fluidized bed boiler in which fuel particles such as coal particles flow in the boiler, as described in a gazette described below. That is,
A desulfurizing agent (for example, a calcium compound such as limestone) is charged into a boiler as a fluidizing medium, and the desulfurizing agent is fluidized together with the fuel particles. Sulfur dioxide) is absorbed by the desulfurizing agent and discharged as gypsum.

The in-furnace desulfurization is revolutionary in that the desulfurization of the flue gas can be performed without requiring a desulfurization device as a separate facility. However, as described in the following gazette, in order to achieve a sufficiently high desulfurization rate (for example, 90% or more) capable of responding to recent strict emission regulations and the like, limestone or the like, which is a desulfurizing agent, needs to be used. (For example, a molar ratio of Ca / S of 3 or more). In this case, a large amount of unreacted desulfurizing agent is discarded, which increases operating costs and increases the height of the fluidized bed. There is a problem that it becomes difficult to achieve good combustion.

Therefore, in the processing method disclosed in Japanese Patent Laid-Open No. 3-293015, coal ash in a boiler containing an unreacted desulfurizing agent is first extracted from the boiler and introduced into a slurry manufacturing apparatus. After the slurry is formed in the spray dryer, a secondary desulfurization step is performed in which the sulfur is blown into the flue gas in the spray dryer type desulfurizer, and the sulfur dioxide remaining in the flue gas is absorbed by the desulfurizing agent in the blown slurry and collected as gypsum. I have. According to this method, the desulfurization load of the in-furnace desulfurization (primary desulfurization step) is reduced by the amount processed in the secondary desulfurization step,
Since the amount of the desulfurizing agent to be charged into the boiler can be reduced and the unreacted desulfurizing agent remaining in the boiler can be effectively used, the above-mentioned problem of the furnace desulfurization can be considerably solved.

Next, as a technique for removing nitrogen oxides from flue gas, an ammonia catalytic reduction method using a catalyst is known.
This method is general, and this method is also effective for the flue gas treatment of the fluidized bed boiler described above. That is, using a well-known denitration apparatus configured by a flow section of flue gas loaded with a denitration catalyst, and a means for uniformly blowing ammonia into the flow section, flowing the flue gas through this denitration apparatus, This is a method of decomposing and removing nitrogen oxides in flue gas with ammonia. In the case of a fluidized-bed boiler, lower-temperature combustion is possible as compared with a general boiler, and the amount of nitrogen oxides discharged from the boiler can be reduced as described above. However, from the viewpoint of responding to the emission regulations that have been increasingly tightened in recent years and further purifying the smoke emission to prevent air pollution, the concentration is not sufficient, and the denitration equipment described above is naturally installed downstream of the boiler. Is required.

[0008] In the above-mentioned publication, description and illustration of the denitration process are not found, but actually, it is necessary to separately provide the denitration device as described above. In the above publication, there is no description or illustration of a gas turbine or the like as a power generation system. However, in the case of combined power generation, actually, for example, the downstream side of the multi-cyclone 3 (the upstream side of the air heater 5) in FIG. The gas turbine is located at the position (1), and the steam turbine is driven by heat obtained by the boiler 1, the air heater 5, and the like.

[0009]

According to the flue gas treatment method disclosed in the above publication (Japanese Unexamined Patent Publication No. 3-293015), compared with the case where desulfurization treatment is performed only by furnace desulfurization, Certainly, it is possible to reduce the operating cost, and it is possible to easily realize good combustion in the boiler while maintaining a more preferable fluidized bed height. Further, by providing the above-described denitration apparatus, the nitrogen oxide concentration can be reduced to a necessary level. However, large-scale equipment, such as a slurry production device and a spray dryer type desulfurization device, which is not much different from the desulfurization device used for conventional coal-fired power generation, is required separately. There is a problem that equipment costs increase due to desulfurization treatment performed outside the boiler.

Accordingly, it is a first object of the present invention to provide a method for treating flue gas which can realize desulfurization treatment of flue gas generated in a fluidized-bed boiler with a simpler equipment configuration. It is a second object of the present invention to provide a flue gas treatment method in which the flue gas degassing process can be realized by the same apparatus as the flue gas denitration process, and the facility configuration can be further simplified.

[0011]

In order to achieve the above object, a method for treating flue gas in a fluidized-bed boiler according to the first aspect of the present invention comprises removing at least sulfur dioxide from flue gas generated in a fluidized-bed boiler. In a method, in the fluidized-bed boiler, a desulfurizing agent is fluidized together with fuel particles, and an in-furnace desulfurizing step in which sulfur dioxide in flue gas generated by combustion of the fuel particles is absorbed by the desulfurizing agent, A conversion step of converting sulfur dioxide remaining in the flue gas discharged from the fluidized-bed boiler into sulfur trioxide by a conversion catalyst; and a trioxide in the flue gas containing the sulfur trioxide generated in the conversion step. It is characterized by having a precipitation step of reacting sulfur with the injected ammonia to precipitate as ammonium sulfate, and a dust removing step of removing solids in flue gas containing ammonium sulfate generated in the precipitation step.

Further, in the method for treating flue gas of a fluidized-bed boiler according to claim 2, the flue gas discharged from the fluidized-bed boiler is
A denitration step of decomposing and removing nitrogen oxides contained in the flue gas by contacting with ammonia injected in the presence of a denitration catalyst, wherein the conversion catalyst and the denitration catalyst are sequentially loaded inside In the processing apparatus described above, at least the conversion step is performed together with the denitration step.

Further, in the method for treating flue gas of a fluidized-bed boiler according to claim 3, the flue gas discharged from the fluidized-bed boiler is
A denitration step of decomposing and removing nitrogen oxides contained in the flue gas by contacting the injected ammonia in the presence of a denitration catalyst, further comprising a catalyst that functions as the conversion catalyst and the denitration catalyst. In the processing apparatus loaded inside, at least the conversion step is performed together with the denitration step.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. (First Example) FIG. 1 is a diagram showing a combined cycle power generation system as a first example to which the present invention is applied. Since the present invention has a feature in the configuration of the smoke exhaust treatment, the detailed configuration of the power generation system itself (for example, the configuration of the steam cycle and the like) is omitted in the drawing.

In the pressurized fluidized bed boiler (PFBC) 1, for example, coal particles are burned while flowing together with limestone as a desulfurizing agent, and the steam for driving the steam turbine 4 is heated, and the flue gas A1 is discharged. You. In the boiler 1, sulfur dioxide generated mainly by combustion of coal particles is removed from the flue gas by being absorbed by the limestone and fixed as gypsum (furnace desulfurization step). Here, C
The molar ratio of a / S is set as low as 2-3, for example, and
Achieve a desulfurization rate of about 0%. Therefore, sulfur dioxide slightly remains in the flue gas A1 discharged from the boiler 1. It is known that sulfur trioxide is generally hardly discharged from a pressurized fluidized-bed boiler that performs in-furnace desulfurization. In this case, too, the concentration of sulfur trioxide in the flue gas A1 is almost equal to zero.

The flue gas A1 discharged from the boiler 1 is
First, it is sent to the dust removing means 2 to remove dust composed of unburned carbon, unreacted limestone, and the like. The dust removing means 2 is composed of, for example, a cyclone, a porous filter, or a combination thereof. The dust removed here is, for example, boiler 1
Is sent to a reburning chamber (not shown) and reused. Next, the smoke exhaust A1 is introduced into the gas turbine 3. In the gas turbine 3, the generator 5 is driven by the energy of the exhaust gas A1 having a high temperature and a high pressure to generate power.

The power generation system according to the present embodiment is a so-called combined power generation system including a gas turbine 3 and a steam turbine 4. In the case of FIG. Is driven. Also,
As the high-temperature and high-pressure steam for driving the steam turbine 4, those generated by heating by the boiler 1 or a heat recovery unit 6 described later are used.

Next, the flue gas A2 discharged after working in the gas turbine 3 is introduced into the denitration device 7. The temperature of the flue gas A2 is about 450 ° C. to 550 ° C. Here, the denitration device 7 is provided for performing a denitration step of decomposing nitrogen oxides in the flue gas A2, and decomposes nitrogen oxides by an ammonia catalytic reduction method using a denitration catalyst. That is, ammonia B is injected into the denitration apparatus 7 or upstream of the denitration apparatus 7 and is evenly distributed to the smoke exhaust section inside the denitration apparatus 7 loaded with the denitration catalyst. The substance comes into contact with this ammonia B and is decomposed by a well-known reaction. As the denitration catalyst in this case, a well-known catalyst (for example, one containing TiO ₂ and WO ₃ as main components) used for denitration treatment of boiler flue gas in a general coal-fired power generation facility in recent years is used. be able to.

The conventional denitration catalyst has not only a function of accelerating the decomposition reaction of nitrogen oxides, but also a secondary function of accelerating the conversion reaction of converting sulfur dioxide in flue gas into sulfur trioxide. Was. However, for a general desulfurization unit that absorbs and removes sulfur oxides in the form of sulfur dioxide, sulfur trioxide is difficult to absorb and becomes corrosive sulfuric acid mist when cooled, so it is treated as a harmful substance. Have been. For this reason, recent general denitration catalysts are adjusted to have properties that hardly have the function of accelerating the conversion reaction by adding special components or the like, and almost no sulfur trioxide is generated.

The amount of ammonia B to be injected in the denitration apparatus 7 or in the upstream of the denitration apparatus may be changed as required.
It may be set in excess of the amount required for denitration. For example,
The trace amount of sulfur trioxide originally contained in the flue gas A2 and almost the entire amount of sulfur trioxide generated in the flue gas in the denitration device 7 or in the conversion step described later react with the excess ammonia. It may be configured to inject a larger amount so as to obtain ammonium sulfate ((NH ₄ ) ₂ SO ₄ ). In this way, in the heat recovery unit 6 and the like described later, the possibility and the ratio of sulfur trioxide in flue gas to become harmful sulfuric acid mist and acidic ammonium sulfate (NH ₄ HSO ₄ ) are almost eliminated, and sulfur trioxide is reduced. The problems of scale generation and material corrosion in the heat recovery unit 6 and the like due to the above can be avoided with high reliability.

Next, the flue gas A2 after the denitration treatment is introduced into the converter 10, and almost all of the sulfur dioxide remaining in the flue gas A2 reacts with the oxygen in the flue gas by the conversion catalyst. To be converted to sulfur trioxide (conversion step). Here, the converter 10 is one in which a conversion catalyst is loaded in a flue gas circulation section. As the conversion catalyst, for example, Si such as diatomaceous earth
A carrier obtained by coating a carrier containing O ₂ as a main component and supporting platinum as a catalyst main component on a honeycomb-shaped cordierite substrate can be used. When such a catalyst is used under the condition that the temperature of the flue gas A2 is 450 to 550 ° C., for example, the content of platinum is 2 g /
When the gas contact area is 1950 m ² / m ³ in liter,
SV value indicating the amount of catalyst charged (processing flow rate (m ³ / hr) /
If the amount of catalyst (m ³ ) is set to 2000 (hr ^-1 ),
It has been found from studies by the inventors that a high conversion rate of 80% or more can be achieved.

The sulfur trioxide generated in the above-mentioned conversion step or a trace amount of sulfur trioxide originally contained in the flue gas A2 or A3 is discharged into the converter 10, the flue before and after the converter 10, or the heat In the recovery unit 6 or in a flue before and after the recovery unit 6, in this case, the remaining ammonia B injected before or after the denitration apparatus 7 or the ammonia B injected before and after the heat recovery unit 6 described below, and Reacts with the moisture in the flue gas and precipitates as ammonium sulfate ((NH ₄ ) ₂ SO ₄ ) (precipitation step). This precipitation step is preferably performed at a temperature of 200 ° C. or lower, and the precipitation reaction effectively proceeds in this temperature range. Therefore, as shown in FIG. 1, the ammonia B for converting sulfur trioxide in the flue gas into ammonium sulfate is, as shown in FIG. 1, the flue gas A4 having a low temperature of about 120 ° C. to 200 ° C. (the downstream side of the heat recovery unit 6). May be injected. However, as described above, in order to more reliably prevent a problem caused by the generation of sulfuric acid mist and acidic ammonium sulfate in the heat recovery unit 6 and the like,
A configuration in which ammonia B for converting sulfur trioxide into ammonium sulfate is injected into flue gas is preferable. For example, as an extreme mode, ammonia B is used only in the denitration device 7 or its upstream.
May be injected, so that all of the ammonia B required for the denitration step and the required amount for the precipitation step may be injected. In this case, the location for injecting ammonia B is one location, and there is also an effect that the equipment configuration is simplified.

Next, the flue gas A3 that has passed through the denitration device 7 and the converter 10 is introduced into the heat recovery unit 6. The heat recovery unit 6 recovers heat from the flue gas A3, generates or heats steam supplied to the steam turbine 4 for combined power generation, or heats the combustion air sent to the boiler 1. It is. The temperature of the flue gas A3 introduced into the heat recovery unit 6 is approximately 450 ° C. to 550 ° C., and the temperature of the cooled flue gas A4 derived from the heat recovery unit 6 is 1 °.
It is about 20 ° C to 200 ° C.

Next, the flue gas A4 led out of the heat recovery unit 6 is introduced into a dust removing means 8 such as a dry electric precipitator to remove the solid content C containing ammonium sulfate (dust removing step).
Thereafter, the smoke is discharged from the chimney 9 to the atmosphere as clean smoke A5. According to the conversion step, the precipitation step, and the dust removal step, sulfur dioxide in flue gas is removed as sulfuric acid (solid content) via sulfur trioxide, so that a so-called desulfurization treatment is realized. In this desulfurization treatment, a high desulfurization rate (for example, 80% or more) is possible by sufficiently supplying ammonia, so that the overall desulfurization rate combined with the in-furnace desulfurization step described above is a sufficiently high value ( For example, 90% or more) can be achieved.

As described above, in the flue gas treatment method implemented in the power generation facility of the present embodiment, a sufficiently high desulfurization rate is achieved as a whole, even if the amount of the desulfurizing agent charged into the boiler 1 is set to a small amount. Further, nitrogen oxides in the exhaust gas are sufficiently removed in the denitration process by the denitration device 7. For this reason, the flue gas A5 discharged to the atmosphere becomes clean containing almost no sulfur oxides and nitrogen oxides, and it is easy to maintain good combustion in the boiler. Moreover, as an independent equipment configuration for desulfurization treatment outside the boiler, a simple configuration having only the converter 10 is provided, and equipment costs can be kept low.

(Second Example) Next, FIG. 2 is a diagram showing a combined cycle power generation system as a second example to which the present invention is applied. FIG.
The same components as those in the first example shown in FIG. In this example, the converter 10 described above is used.
It has a denitration device 7a (processing device) that also functions as a device, and is characterized in that it does not have an independent facility corresponding to the converter 10 described above. In the denitration device 7a, for example, the above-described denitration catalyst and conversion catalyst are sequentially loaded in a flue gas circulation section. In this case, the aforementioned denitration step and conversion step,
The deposition process is performed in the denitration apparatus 7a, or the heat exchanger 6b or the flue in the downstream.

Therefore, according to the present embodiment, the same effect as that of the first embodiment can be obtained, and further, the facility cost can be further reduced because the independent converter is not provided. That is, no separate equipment for desulfurization is required outside the boiler, and the equipment configuration becomes extremely simple. In this case, as the denitration device 7a, a device in which one type of catalyst functioning as the conversion catalyst and the denitration catalyst described above may be used. As described above, conventional denitration catalysts (for example, those containing vanadium and / or iron as a main component) also have an action of promoting the production of sulfur trioxide from sulfur dioxide in the first place. A catalyst having such two catalytic actions simultaneously is feasible. For example, when TiO ₂ is used as a carrier and V ₂ O ₅ is
A catalyst containing not more than 1 wt% and 1 to 5 wt% of Fe ₂ O ₃ can be used. When such a catalyst is used, the temperature condition of the catalytic reaction (the above-described denitration reaction or conversion reaction) is preferably set to about 350 to 450 ° C., and the SV value indicating the charged amount of the catalyst is: , 50
It is preferably set to ^{0 to} 1000 (hr ^-1 ). With such a configuration using one type of catalyst, the physical configuration of the denitration device 7a is the same as the conventional one, and the equipment configuration is simplified, and the maintenance and management of the catalyst is also facilitated.

In the embodiment shown in FIG. 2, the heat recovery unit 6
The a and 6b are arranged before and after the denitration device 7a to recover heat from the flue gas, and the temperature of the flue gas in the denitration device 7a (that is, the temperature of the catalytic reaction) is adjusted to an optimum temperature. For example, with such a configuration, the temperature of the flue gas in the denitration apparatus 7a is adjusted to about 250 to 400 ° C., and the temperature of the flue gas A4 after the treatment is set to 120 to 200 ° C.
° C. In addition, the arrangement position of the heat recovery unit is not limited to such an embodiment. For example, the denitration device 7
As a, when a catalyst in which a denitration catalyst and a conversion catalyst similar to those of the first example are sequentially loaded is used, higher temperature conditions are preferable, and heat recovery is performed on the upstream side of the denitration device 7a. There may be no configuration (the configuration in which the heat recovery unit 6a is omitted in FIG. 2). Also, in the configuration of the second example illustrated in FIG. 2, the injection position of ammonia B may have various modes. For example, the injection of ammonia for precipitating ammonium sulfate may be performed downstream of the heat recovery unit 6a,
It may be performed in the denitration apparatus 7a or upstream of the denitration apparatus 7a together with ammonia for the denitration treatment. Alternatively, the denitration device 7a
Alternatively, the insufficient amount of ammonia B in the excessive injection of ammonia performed in the upstream may be additionally injected into the exhaust gas A4 in the downstream of the heat recovery unit 6a.

[0029]

According to the present invention, sulfur dioxide remaining in the flue gas discharged from the boiler which cannot be removed in the furnace desulfurization step is converted to sulfur trioxide by the conversion catalyst in the conversion step,
It reacts with the ammonia injected in the precipitation step to precipitate as ammonium sulfate, and is further removed as a solid in the dust removal step. That is, according to the conversion step, the precipitation step, and the dust removal step of the present invention, sulfur dioxide remaining in the flue gas is removed as ammonium sulfate (solid content) via sulfur trioxide, so that a so-called desulfurization treatment is realized. Become. In this desulfurization treatment, a sufficient desulfurization rate (for example, 80%
Above) is possible. For this reason, even if the amount of the desulfurizing agent to be charged into the boiler for the desulfurization in the furnace is set to a small amount in consideration of the desulfurization rate of, for example, about 50%, the desulfurization rate as a whole is sufficiently high (for example, 90% or more). ) Is achieved. For this reason, the flue gas emitted to the atmosphere is clean with at least little sulfur dioxide and sulfur trioxide,
Moreover, it becomes easy to maintain good combustion in the boiler. In addition, if a general denitrification treatment is performed in addition to the desulfurization treatment, it goes without saying that the flue gas discharged to the atmosphere is also clean in terms of nitrogen oxide concentration.

The conversion step and the precipitation step of the present invention are performed by a converter having a simple structure in which the conversion catalyst is simply loaded therein, and a nozzle or the like for injecting and spraying ammonia into a flow section of the flue gas. It can be easily realized only by means, and the above-mentioned dust-removing process can be easily performed by general dust-removing means (eg, dry electric dust collector, Filters, etc.)
Can be realized. That is, as an independent equipment configuration for desulfurization treatment outside the boiler, a simple configuration having only the converter and the injection means is provided, and the equipment cost can be reduced.

Normally, in this type of flue gas treatment facility, a process of removing nitrogen oxides in flue gas (denitration step)
In this case, if a general denitration apparatus is used, ammonia injection is performed as described above. For this reason, if the amount of ammonia required for the above-mentioned deposition step is also injected into the flue gas using the means for injecting ammonia in this denitration apparatus, it is not necessary to separately provide the means for injecting ammonia. As an independent equipment configuration for desulfurization treatment outside the boiler, a simpler configuration having only the converter is provided, and the equipment cost can be further reduced.

According to a second aspect of the present invention, in the processing apparatus, the conversion catalyst and the denitration catalyst are sequentially loaded inside.
If at least the conversion step is performed together with the denitration step, the facility cost can be further reduced because no independent converter is provided. That is, no separate equipment for desulfurization is required outside the boiler, and the equipment configuration becomes extremely simple.

According to a third aspect of the present invention, in the processing apparatus in which the conversion catalyst and the catalyst functioning as the denitration catalyst are loaded, at least the conversion step is performed together with the denitration step. Since there is no separate converter, it is possible to further reduce the equipment cost and to use a single type of catalyst, so that the maintenance and management of the catalyst becomes easy.

[Brief description of the drawings]

FIG. 1 is a diagram showing a PFBC combined cycle power plant which is an example of the present invention.

FIG. 2 is a diagram showing a PFBC combined cycle power plant as another example of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pressurized fluidized-bed boiler 2 Dust removing means (cyclone or porous filter, etc.) 3 Gas turbine 4 Steam turbine 5 Generator 6, 6a, 6b Heat recovery unit 7 Denitration unit 7a Denitration unit (processing unit) 8 Dust removal unit (dry electric dust collector) Etc.) 9 Chimney 10 Converter A1 to A5 Smoke exhaust B Ammonia C Solid content (including ammonium sulfate)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kozo Iida 4-22, Kannonshinmachi, Nishi-ku, Hiroshima-shi, Hiroshima Mitsubishi Heavy Industries, Ltd. Hiroshima Research Laboratory (72) Inventor Susumu Okino 4-chome, Kannonshinmachi, Nishi-ku, Hiroshima-shi, Hiroshima No.6-22 Mitsubishi Heavy Industries, Ltd. Hiroshima Research Laboratory F term (reference) 3K070 DA02 DA03 DA07 DA14 DA16 DA23 DA25 DA29 DA30 DA48 DA53 DA58 DA85 4D002 AA02 AA12 AC01 BA03 BA05 BA06 BA14 CA09 CA11 CA13 DA05 DA07 DA11 DA16 DA21 DA25 DA46 EA02 FA03 FA06 GA01 GA02 GB01 GB02 GB03 GB06 HA10 4D048 AA02 AA06 AB01 AB02 AB03 AC04 BA07X BA09X BA23X BA27X BA30X BA36X BA41X BB02 CA03 CC32 CD01 CD03 DA02 DA03 DA05 DA06 DA10 DA12

Claims (3)

[Claims] 1. A flue gas treatment method for removing at least sulfur dioxide from flue gas generated in a fluidized bed boiler, comprising: fluidizing a desulfurizing agent together with fuel particles in the fluidized bed boiler; Furnace desulfurization step of absorbing the sulfur dioxide in the flue gas generated by combustion of the flue gas into the desulfurizing agent, and converting sulfur dioxide remaining in the flue gas discharged from the fluidized-bed boiler into sulfur trioxide by a conversion catalyst. A conversion step of converting the sulfur trioxide in the flue gas containing sulfur trioxide generated in this conversion step into a reaction with the injected ammonia to precipitate as ammonium sulfate, and the ammonium sulfate generated in the precipitation step And a dust removing step of removing solids in the flue gas containing the flue gas. 2. A denitration step of decomposing and removing nitrogen oxides contained in the flue gas by contacting the flue gas discharged from the fluidized-bed boiler with ammonia injected in the presence of a denitration catalyst. The processing apparatus in which the conversion catalyst and the denitration catalyst are sequentially loaded therein, wherein at least the conversion step is performed together with the denitration step. Smoke treatment method. 3. A denitration step for decomposing and removing nitrogen oxides contained in the flue gas by bringing the flue gas discharged from the fluidized bed boiler into contact with ammonia injected in the presence of a denitration catalyst. The fluidized bed according to claim 1, further comprising: a processing apparatus in which the conversion catalyst and the catalyst functioning as the denitration catalyst are loaded inside, wherein at least the conversion step is performed together with the denitration step. Boiler exhaust gas treatment method.