JP7173981B2 - Circulating fluidized bed boiler and its operation method - Google Patents

Description

The present invention relates to a circulating fluidized bed boiler and its operating method.

In recent years, there have been many demands to use new energy fuels such as biomass fuels in boiler facilities.

Patent Document 1 discloses a technique of supplying a compound containing sulfate into a steam boiler or a superheater area in order to reduce the deposition of chlorides in the superheater in a boiler facility that uses biomass fuel. .

Further, Patent Literature 2 discloses a technique of intermittently allowing SO ₂ gas to coexist in a combustion furnace to combust combustibles in order to remove chlorides adhering to the surfaces of heat transfer tubes. FIG. 2 of Patent Document 2 discloses a structure in which an SO ₂ gas supply pipe is connected to a fluidizing air supply pipe of an intrabed circulating fluidized bed furnace.

International Publication No. 2006/134227 JP-A-9-303743

Many biomass fuels contain large amounts of alkali salts, and when used as fuel, the adherence of alkali salts to the superheater and the resulting corrosion of the superheater become a problem.

On the other hand, the technique of Patent Document 1 attempts to reduce the accumulation of chlorides in the superheater by supplying a compound containing sulfate into the superheater region. Further, in the technique of Patent Document 2, the chloride adhering to the surface of the heat transfer tube is peeled off by burning the combustible material in the presence of SO ₂ gas. However, in these methods, when a fuel containing a large amount of alkali salts is used and the exhaust gas contains an extremely large amount of alkali salts, it is difficult to efficiently chemically react the alkali salts in the exhaust gas. there were.

The present invention is a circulating fluidized bed that can efficiently remove alkali salts contained in exhaust gas even when fuel containing a large amount of alkali salts is used, and can suppress the adhesion of alkali salts to the superheater and the resulting corrosion of the superheater. An object of the present invention is to provide a boiler and its operation method.

The circulating fluidized bed boiler according to the present invention is
a furnace;
a solid-gas separator for collecting solid particles discharged from the furnace;
a return section in which the solid particles collected by the solid-gas separator are retained before being returned to the furnace;
an introduction section for introducing a sulfur element-containing compound into the return section;
a first measuring unit for measuring the concentration of the sulfur element-containing compound in a passage between the solid-gas separation device and the return unit;
A control unit that controls the introduction amount of the sulfur element-containing compound using the measurement result of the first measurement unit;
It was configured to include

A method for operating a circulating fluidized bed boiler according to the present invention includes:
A furnace, a solid-gas separation device for collecting solid particles discharged from the furnace, and a return section in which the solid particles collected by the solid-gas separation device are retained before being returned to the furnace. A method of operating a circulating fluidized bed boiler, comprising:
introducing a sulfur element-containing compound into the return section;
measuring the concentration of the sulfur element-containing compound in a passage between the solid-gas separation device and the return section;
A method of controlling the introduction amount of the sulfur element-containing compound using the measurement result of the concentration of the sulfur element-containing compound is employed .

According to the present invention, even if a fuel containing a large amount of alkali salt is used, the alkali salt contained in the exhaust gas can be efficiently removed, and the adhesion of the alkali salt to the superheater and the resulting corrosion of the superheater can be suppressed. effect is obtained.

1 is a configuration diagram showing a circulating fluidized bed boiler according to Embodiment 1 of the present invention; FIG. FIG. 2 is a configuration diagram showing details around a flow material return portion of FIG. 1 ; 4 is a flowchart showing a procedure of SO ₂ gas introduction processing executed by a control unit; 4 is a time chart for explaining SO ₂ gas introduction processing executed by a control unit; Fig. 2 is a configuration diagram showing a circulating fluidized bed boiler according to Embodiment 2 of the present invention; FIG. 3 is a configuration diagram showing a circulating fluidized bed boiler according to Embodiment 3 of the present invention;

Hereinafter, each embodiment of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 is a configuration diagram showing a circulating fluidized bed boiler according to Embodiment 1 of the present invention. FIG. 2 is a block diagram showing the details of the periphery of the flow material return portion of FIG.

A circulating fluidized bed boiler 1 according to Embodiment 1 of the present invention, as shown in FIG. 12, and a flue 13. The circulation section 12 is provided with an introduction section 125 through which the SO2 gas is introduced, a _first measurement section 126 that measures the concentration of the SO2 gas, and a _second measurement section 127 that measures the HCl concentration. Furthermore, the circulating fluidized bed boiler ₁ includes superheaters 14a and 14b, an SO2 tank 15, a variable flow valve 16, a dust collector 17, a pump 18, a chimney 19 and a controller 20.

The furnace 10 is a circulating fluidized bed combustion furnace, and uses silica sand or the like as a fluidizing material (also referred to as "fluidized sand" or "bed material"), and fuels such as biomass fuel, low-grade coal, sludge, waste plastics, and waste tires. to burn.

The solid-gas separator 11 is, for example, a cyclone, and separates the exhaust gas discharged from the furnace 10 from solid particles (fluidized material, etc.). The separated exhaust gas is sent to the flue 13 , and the separated solid particles are collected and sent to the circulation section 12 .

The circulation section 12 includes a downcomer 121, a return section 122, a partition 123, and a return chute 124, as also shown in FIG. The downcomer 121 is a passage that connects the solid-gas separation device 11 and the return section 122, and causes the solid particles collected by the solid-gas separation device 11 to descend to the return section 122 by gravity. The return chute 124 is a passage that connects the return section 122 and the furnace 10, and returns the solid particles from the return section 122 to the furnace 10 by gravity. The return section 122 is a space in which collected solid particles are retained before being returned to the furnace 10 .

The partition 123 separates the space of the return section 122 between the downcomer 121 and the return chute 124 . The partition 123 partitions at least the upper part of the space of the return part 122 from the middle stage, and the lower part is open. The lower part opened by the partition 123 is always filled with solid particles (fluid material). The portion filled with the solid particles and the partition 123 form a loop seal, which blocks the flow of gas from the furnace 10 to the flue 13 in the circulation section 12 and allows only the solid particles to return to the furnace 10. to

An introduction section 125 that introduces the SO ₂ gas into the return section 122 is arranged below the return section 122, for example. The introduction part 125 also serves as an introduction part for introducing fluid air for fluidizing the solid particles, although not particularly limited, and the SO ₂ gas is added to the fluid air and introduced to the return part 122 . Specifically, SO ₂ is supplied from the SO ₂ tank 15 in which the SO ₂ gas is accumulated or generated to the fluidizing air pipe 21 via the flow rate variable valve 16 . Then, SO ₂ gas is supplied to the return portion 122 by sending this flowing air to the return portion 122 via the introduction portion 125 . The SO ₂ gas and fluidizing air introduced into the return section 122 have the effect of fluidizing the solid particles and sending them to the furnace 10 through the return chute 124 . Since the SO ₂ gas and fluidized air introduced into the return section 122 have a lower pressure than the exhaust gas of the furnace 10 , they do not flow into the furnace 10 but rise through the downcomer 121 and flow into the flue 13 .

The first measurement unit 126 and the second measurement unit 127 are arranged in the downcomer 121 and measure the concentration of SO ₂ gas and the concentration of HCl gas in the gas passing through the downcomer 121 . Among the first measurement unit 126 and the second measurement unit 127, a filter that allows only gaseous components to pass is provided around the measurement element arranged in the downcomer 121, and the first measurement unit 126 and the second measurement unit 127 can measure the concentration of gas by eliminating the influence of solid components. Note that the first measurement unit 126 and the second measurement unit 127 may be configured to measure another physical quantity and convert the measured physical quantity to obtain the gas concentration instead of directly measuring the gas concentration. good.

The control unit 20 inputs the measurement results of the first measurement unit 126 and the second measurement unit 127 and controls the flow rate variable valve 16 to control the introduction amount of SO ₂ gas to the return unit 122 .

One superheater 14a is provided in the flue 13 and receives the heat of the high-temperature exhaust gas to superheat the steam. The other superheater 14b is provided in the return section 122 of the circulation section 12 and receives the heat of the high temperature fluid material to superheat the steam.

An economizer that preheats hot water using residual heat of exhaust gas and an air preheater that preheats combustion air using residual heat of exhaust gas are provided in the flue 13 after the superheater 14a. may

The dust collector 17 is a bag filter, an electric dust collector, or the like, and collects dust from low-temperature exhaust gas.

A pump 18 and a chimney 19 expel the flue gas into the air.

<Combustion operation>
In the circulating fluidized bed boiler 1 configured as described above, fuel such as biomass fuel containing a large amount of alkali salt is fed into the furnace 10, while combustion air is supplied to the furnace 10 to burn the fuel. When the fuel is burned, a large amount of gaseous MCl (M is K (potassium), Na (sodium), etc.), which is an alkali salt, is generated and discharged from the furnace 10 together with the exhaust gas. Also, some of the solid particles are expelled from the furnace 10 by the force of the exhaust gas. In the solid-gas separator 11, the exhaust gas discharged from the furnace 10 is separated from the solid particles, and the solid particles are collected. When the solid particles and exhaust gas are separated, the solid particles are exposed to the exhaust gas, and a large amount of MCl adheres to the solid particles. Most of the solid particles are fluid material and are returned to the circulation section 12 . The remaining MCl not attached to solid particles is sent to flue 13 .

The fluid material to which a large amount of MCl adheres is retained in the return section 122 and is exposed to the introduced SO ₂ gas. The fluid material retained in the return portion 122 is uniformly exposed to the SO ₂ gas while being fluidized by the fluid air. At this time, for example, a chemical reaction represented by the reaction formula (1) occurs, and MCl adhering to the fluid material is converted into HCl (hydrogen chloride) and M ₂ SO ₄ (M is K (potassium), Na (sodium, etc.) In general, a solid-gas reaction can promote a chemical reaction more efficiently than a gas-gas reaction, and in the return section 122, the solid-gas reaction can efficiently promote reaction (1) chemical reaction is obtained.

MCl ₊ SO2 _{+ H2O} →HCl+ _M2SO4 (1)

The HCl gas produced in the return section 122 flows through the downcomer 121 into the flue 13, and the M ₂ SO ₄ produced in the return section 122 is returned to the furnace 10 together with, for example, the fluid material to form a liquid powder. is recovered from the furnace 10 as

Further, part of the SO ₂ gas introduced into the return section 122 and not chemically reacted passes through the downcomer 121 and flows into the flue 13 . At that time, this SO ₂ gas chemically reacts with MCl discharged into the flue 13 and has the effect of reducing MCl in the exhaust gas of the flue 13 .

<SO ₂ gas introduction process>
Fuels such as biomass fuels vary in content of alkali salts (MCl). Therefore, the control unit 20 performs control so that the introduction amount of the SO ₂ gas is optimized according to the alkali salt content. Next, the process of controlling the introduction amount of SO ₂ gas by the control unit 20 will be described.

FIG. 3 is a flow chart showing the procedure of SO ₂ gas introduction processing executed by the control unit. FIG. 4 is a time chart for explaining SO ₂ gas introduction processing executed by the control unit. In FIG. 4, "amount of mixed MCl" indicates the amount of alkali salt mixed in the fuel. “Measured amount of SO ₂ ” and “measured amount of HCl” indicate concentrations of SO ₂ and HCl measured by the first measurement unit 126 and the second measurement unit 127 . “SO ₂ introduction amount” indicates the introduction amount of SO ₂ to the return section 122 . In FIG. 4, the scale of "measured amount of SO ₂ " is enlarged more than the scale of "measured amount of HCl".

As shown in FIG. 3, in the SO ₂ gas introduction process, the control unit 20 repeatedly executes the loop process of steps S1 to S8 in short cycles during the period in which the fuel containing alkali salt is supplied. In this loop process, the control unit 20 first acquires the concentration of SO ₂ gas and the concentration of HCl gas in the downcomer 121 (steps S1 and S2). The flow rate of the gas flowing through the downcomer 121 is constant, and the concentrations of SO ₂ gas and HCl gas are substantially proportional to the flow rates of SO ₂ gas and HCl gas flowing through the downcomer 121 . Therefore, the control unit 20 can convert the concentrations into the flow rates of the SO ₂ gas and the HCl gas by multiplying the concentrations by the constant of proportionality.

If the flow rate of the gas passing through the downcomer 121 is not constant, in steps S1 and S2, the control unit ₂₀ multiplies the flow rate of the gas by the concentration, the flow rate of the SO2 gas passing through the downcomer 121, HCl Gas flow rates may be calculated. Then, the control unit 20 may be configured to perform the subsequent determination steps (S3, S5, S7) based on the flow rate instead of the concentration.

In the loop processing of steps S1 to S8, the control unit 20 determines whether the SO ₂ gas concentration obtained in step S1 is below the set lower limit (step S3) or above the set upper limit (step S5). . Here, the set _lower limit value is the concentration of SO2 gas measured by the downcomer 121 when the alkali salt is sufficiently abundant with respect to the amount of introduced _SO2 gas. It is a value preset as a slightly larger value than . _The set upper limit value is set in advance so as to indicate the concentration of SO2 gas measured by the downcomer 121 when the introduced _SO2 gas is slightly rich with respect to the amount of alkali salt. value. As shown in the _time chart of "SO ₂ measurement amount" in _FIG . can be considered to be a suitable amount to chemically react with the alkali salt of

If the determination result of step S3 is YES, the controller 20 increases the introduction amount of the SO ₂ gas (step S4, see periods T1 and T3 in FIG. 4). Further, if the determination result in step S4 is YES, the control unit 20 reduces the SO ₂ gas introduction amount (step S6, see period T2 in FIG. 4).

Further, if both determination results in steps S3 and S4 are NO, the control unit 20 determines whether the concentration of HCl gas obtained in step S2 has decreased (step S7). Specifically, the control unit 20 removes, for example, an error component from a series of changes in the concentration of HCl gas obtained in step S2 in a plurality of loop processes, and compares the rate of change with a threshold to obtain HCl It can be determined whether the gas concentration has decreased. As a result, when it is determined that the concentration of HCl gas has decreased, the controller 20 decreases the introduction amount of SO ₂ gas (step S8, see period T2 in FIG. 4).

In the loop processing, if the determination results of steps S3, S5, and S7 are all NO, the control unit ₂₀ returns the processing to step S1 while maintaining the current introduction amount of SO2 gas.

According to the SO ₂ gas introduction process described above, as shown in FIG. 4, when the alkali salt content of the fuel increases or decreases, the SO ₂ gas introduction amount is controlled to increase or decrease. Furthermore, according to the SO ₂ gas introduction process described above, the SO ₂ gas is controlled to be introduced in a slightly larger amount so that the chemical reaction between the MCl and the SO ₂ gas is saturated in the return section 122 . For example, as shown at the end portions of periods T1 and T3 in FIG. 4, when the introduction amount of SO ₂ gas increases and the amount of chemical reaction saturates, the measured amount of HCl saturates, and immediately after that, SO ₂ The amount of gas introduced is maintained. Further, as shown at the end of period T2 in FIG. 4, when the introduction amount of SO ₂ gas is decreased following the decrease in MCl and the chemical reaction amount is saturated, the measured amount of HCl is saturated, and immediately after that, , the introduction amount of SO ₂ gas is maintained.

With such control, a large proportion of the MCl adhering to the circulation material can be chemically reacted with the SO ₂ gas in the return section 122 , and the SO ₂ gas that has not completely reacted passes through the downcomer 121 to the flue 13 . to be sent to Then, the SO ₂ gas sent to the flue 13 chemically reacts with MCl contained in the flue gas of the flue 13 and can act to dilute the MCl in the flue 13 .

In the processing of FIG. 3, the configuration is shown in which the introduction amount of SO ₂ gas is reduced when the condition of step S5 or the condition of step S7 is satisfied. Only the amount of SO ₂ gas introduced may be reduced. As another condition, the control unit 20 may be configured to determine whether or not the amount of HCl gas reaches equilibrium (saturation) during the period in which the introduction amount of SO ₂ gas is being increased. Then, when it is determined that equilibrium has been reached, the controller 20 may be configured to stop increasing the introduction amount of SO ₂ gas and maintain the introduction amount of SO ₂ gas. As a condition for judging equilibrium, a condition under which saturation can be identified by subtracting an error variation, such as when the ratio of the rate of increase of HCl gas to the rate of increase of SO ₂ gas is below a threshold value, may be applied.

As described above, according to the circulating fluidized bed boiler 1 of Embodiment 1 and the operating method thereof, SO ₂ gas is introduced into the return section 122 where the fluidized material collected by the solid-gas separation device 11 is retained. . As a result, even if a large amount of gaseous MCl is discharged into the exhaust gas from the furnace 10, a large proportion of the MCl adheres to the fluid material in the solid-gas separation device 11, and the MCl and SO ₂ gas adhered to the fluid material in the return section 122 and can be efficiently chemically reacted. That is, a large amount of MCl can be removed from the flue gas in the upstream stage of the flue 13 . Therefore, the phenomenon that the fluidized material to which MCl adheres is returned from the return part 122 to the furnace 10, and the MCl is melted again by combustion and discharged into the exhaust gas is significantly reduced, and the MCl concentration in the exhaust gas is significantly reduced. can be reduced to As a result, adhesion of alkali salts to the superheater 14b provided in the return section 122 and the superheater 14a provided in the flue 13 and corrosion of the superheaters 14a and 14b due to the alkali salt can be greatly suppressed.

In particular, when the alkali salt adheres to the superheater 14b arranged in the return section 122, friction of the fluid material occurs in the portion corroded by the adherence of the alkali salt, which tends to reduce the wall thickness. , the thinning of the superheater 14b can be significantly suppressed.

Further, according to the circulating fluidized bed boiler 1 of Embodiment 1, part of the SO ₂ gas introduced into the return section 122 flows through the downcomer 121 into the flue 13 . Therefore, the MCl in the exhaust gas flowing through the flue 13 also reacts with the SO ₂ gas, and the concentration of MCl in the exhaust gas can be further reduced. Also by this, adhesion of the alkali salt to the superheater 14a provided in the flue 13 and corrosion of the superheater 14a by the alkali salt can be further suppressed.

Further, according to the circulating fluidized bed boiler 1 and the operating method thereof of Embodiment 1, the first measuring unit 126 and the second measuring unit 127 that measure the concentration of SO ₂ gas and the concentration of HCl gas, respectively, are downcomers. 121. Then, the introduction amount of SO ₂ gas is controlled based on these measurement results. Since the exhaust gas does not enter the downcomer 121 from the furnace 10, the concentration of SO ₂ gas and the concentration of HCl gas sent from the return part 122 can be measured with little influence of the exhaust gas. Therefore, it is possible to accurately measure the concentrations of the SO ₂ gas and the HCl gas after the chemical reaction in the return section 122, and based on these, it is possible to accurately control the introduction amount of the SO ₂ gas.

Further, according to the circulating fluidized bed boiler 1 of Embodiment 1 and its operating method, the process of increasing or decreasing the introduction amount of SO ₂ gas based on the determination results of steps S3, S5, and S7 in FIG. of _SO2 gas can be introduced.

(Embodiment 2)
FIG. 5 is a configuration diagram showing a circulating fluidized bed boiler according to Embodiment 2 of the present invention.

A circulating fluidized bed boiler 1A of the second embodiment has the same configuration as that of the first embodiment except for the superheater 14b arranged in the return section 122, and the rest is the same as that of the first embodiment.

The SO ₂ gas introduction process in the return section 122 has the effect of significantly reducing MCl flowing into the flue 13 as described above. Therefore, this introduction treatment has the effect of significantly suppressing adhesion of alkali salts to the superheater 14a arranged in the flue 13 and corrosion of the superheater 14a due to the alkali salts.

(Embodiment 3)
FIG. 6 is a configuration diagram showing a circulating fluidized bed boiler according to Embodiment 3 of the present invention.

The circulating fluidized bed boiler 1B of Embodiment 3 is configured such that part of the flue gas sent to the chimney 19 is mixed with the SO ₂ gas from the SO ₂ tank 15 and introduced into the return part 122. Same as form 1.

The flue gas discharged from the chimney 19 contains a small amount of SO ₂ . In order to make effective use of this, in the third embodiment, a pipe 171 is passed from the front stage of the chimney 19 to the return part 122, a part of the exhaust gas sent to the chimney 19 is flowed to the pipe 171, and SO ₂ is It is configured to add SO ₂ gas from tank 15 . Then, the gas is introduced from the pipe 171 to the return portion 122 through the introduction portion 125 .

If the concentration of SO ₂ gas contained in the exhaust gas is substantially constant, the control unit ₂₀ performs the SO ₂ gas introduction process in the same manner as in FIG. Adjustable. On the other hand, if the concentration of SO ₂ gas contained in the exhaust gas changes, this concentration is measured, and the control unit 20 controls the total introduction amount of SO ₂ gas, so that the SO gas supplied to the return unit 122 ₂ gas can be adjusted to the optimum amount.

Each embodiment of the present invention has been described above. However, the present invention is not limited to the above embodiments. For example, in the above embodiment, the configuration in which SO ₂ gas is applied as the sulfur element-containing compound to be introduced into the return section 122 has been described as an example. However, as the sulfur element-containing compound, any sulfur element-containing compound, such as sulfuric acid or sulfide minerals such as pyrite, may be used as long as it is a compound that can replace alkali salts with hydrogen sulfide and sulfide. When sulfuric acid is used, it is introduced into the return section 122 as a liquid, and after introduction, changes to a gas in the return section 122 . Further, when pyrite is used, it is introduced into the return section 122 as a granular solid, and after introduction, the reaction of the following formula (2) is caused by heating, and sulfur oxides can be generated in the return section 122. The introduction part for introducing the sulfur element-containing compound to the return part may be provided at a position above the region where the fluid material stays and upstream of the loop seal.
4FeS ₂ + 11O ₂ → 2Fe ₂ O ₃ + 8SO ₂ (2)

In addition, in the above _- described embodiment, the introduction part 125 of the return part 122 is configured to introduce the SO2 gas and the flowing air _together . may have been Note that the introduction section that introduces gas or fluid into the return section may be called an injection section that injects gas or fluid into the return section.

Further, in the above-described embodiment, the control unit 20 controls switching between increasing, decreasing, and maintaining the SO2 gas immediately after the measurement results of the first measurement unit 126 and the _second measurement unit 127 satisfy a predetermined condition. showed how. However, the control unit 20 may control the introduction amount of the SO ₂ gas based on the measurement results, for example, by PID (Proportional-Integral-Differential) control. In addition, the control unit 20 uses only the measurement result of the first measurement unit 126, or the measurement result of the first measurement unit 126 and the concentration measurement result of substances other than HCl, to determine the introduction amount of SO ₂ gas. may be controlled. Other details shown in the embodiments can be changed as appropriate without departing from the scope of the invention.

INDUSTRIAL APPLICABILITY The present invention can be used for a circulating fluidized bed boiler and its operating method.

Reference Signs List 1, 1A, 1B circulating fluidized bed boiler 10 furnace 11 solid-gas separator 12 circulation section 13 flue 14a, 14b superheater 15 SO ₂ tank 16 variable flow valve 19 stack 20 control section 121 downcomer 122 return section 123 partition 124 return Chute 125 Introduction part 126 First measurement part 127 Second measurement part 171 Pipe

Claims (6)

a furnace;
a solid-gas separator for collecting solid particles discharged from the furnace;
a return section in which the solid particles collected by the solid-gas separator are retained before being returned to the furnace;
an introduction section for introducing a sulfur element-containing compound into the return section;
a first measuring unit for measuring the concentration of the sulfur element-containing compound in a passage between the solid-gas separation device and the return unit;
A control unit that controls the introduction amount of the sulfur element-containing compound using the measurement result of the first measurement unit;
circulating fluidized bed boiler. Further comprising a second measuring unit for measuring the concentration of hydrogen chloride in the passage,
The control unit uses the measurement result of the first measurement unit and the measurement result of the second measurement unit to control the introduction amount of the sulfur element-containing compound.
The circulating fluidized bed boiler according to claim 1 . The control unit
When it is determined that the amount of hydrogen chloride in the passage has reached equilibrium while the introduction amount of the sulfur element-containing compound is increasing, or the amount of the sulfur element-containing compound in the passage is set from a preset lower limit value When it is determined that it is between the upper limit values, maintaining the amount of the sulfur element-containing compound introduced,
increasing the introduction amount of the sulfur element-containing compound when it is determined that the amount of the sulfur element-containing compound in the passage has become lower than the set lower limit;
When it is determined that the amount of the sulfur element-containing compound in the passage has become higher than the set upper limit value, or when it is determined that the amount of the hydrogen chloride in the passage has decreased, the introduction amount of the sulfur element-containing compound decrease the
The circulating fluidized bed boiler according to claim 2 . A furnace, a solid-gas separation device for collecting solid particles discharged from the furnace, and a return section in which the solid particles collected by the solid-gas separation device are retained before being returned to the furnace. A method of operating a circulating fluidized bed boiler, comprising:
introducing a sulfur element-containing compound into the return section;
measuring the concentration of the sulfur element-containing compound in a passage between the solid-gas separation device and the return section;
Controlling the introduction amount of the sulfur element-containing compound using the measurement result of the concentration of the sulfur element-containing compound,
A method of operating a circulating fluidized bed boiler. Measuring the concentration of hydrogen chloride in the passageway,
Controlling the introduction amount of the sulfur element-containing compound using the measurement result of the concentration of the sulfur element-containing compound and the measurement result of the hydrogen chloride concentration,
A method of operating a circulating fluidized bed boiler according to claim 4 . When the amount of hydrogen chloride in the passage reaches equilibrium while the introduction amount of the sulfur element-containing compound is increasing, or when the amount of the sulfur element-containing compound in the passage is changed from a preset lower limit value to a preset upper limit value maintaining the introduction amount of the sulfur element-containing compound when it is between
increasing the introduction amount of the sulfur element-containing compound when the amount of the sulfur element-containing compound in the passage becomes lower than the set lower limit;
When the amount of the sulfur element-containing compound in the passage becomes higher than the set upper limit value, or when the amount of the hydrogen chloride in the passage decreases, reducing the introduction amount of the sulfur element-containing compound.
A method for operating a circulating fluidized bed boiler according to claim 5 .

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