JP2009250571A - Starting method of circulating fluidized bed furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a starting method of a circulating fluidized bed furnace for preventing generation of CO caused by flame-out or instability of flames of a burner on sand at start and enabling prompt and stable start. <P>SOLUTION: In the starting method for the circulating fluidized bed furnace for burning a burned object while mixing it with a fluid medium, the burner 24 on sand is provided above a fluidized bed 2a and a burner 25 in sand is provided within the fluidized bed 2a. The starting method includes: a first process of igniting the burner 24 on sand with the burner 25 in sand stopped and controlling primary air amount and secondary air amount so that superficial velocity becomes below 2.0 m/s at start of the furnace; and a second control process of stopping the burner 24 on sand, injecting fuel from the burner 25 in sand and performing control so that the superficial velocity exceeds 2.0 m/s when the fluidized bed temperature exceeds self-burning temperature of fuel supplied to the burner 25 in sand. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for starting a circulating fluidized bed furnace in which a combusted material is combusted while being mixed with a fluidized medium, and more particularly, a first burner provided above the fluidized bed and a first burner provided in the fluidized bed. The present invention relates to a method for starting a circulating fluidized bed furnace capable of stably and quickly starting up in a circulating fluidized bed furnace having two burners.

  Conventionally, circulating fluidized bed furnaces are widely used in combustion treatment of combustibles such as sewage sludge, municipal waste, industrial waste, and coal. FIG. 6 shows a configuration of a general circulating fluidized bed furnace 61 disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2000-18538) and the like. The bottom of the riser 62 is filled with a fluid medium, and the fluidized bed 62a is formed by introducing the primary air from the primary air inlet 65 and fluidizing the fluid medium. Combusted matter is burned and mixed while being mixed with the fluidized medium in the fluidized bed 62a, and the scattered fluid is accompanied to the free board 62b by the secondary air introduced from the secondary air inlet 66. The unburned portion is completely burned, the fluid medium is separated from the combustion exhaust gas by the cyclone 63, the fluid medium is returned to the riser 52 via the seal pot 64, and the fluid medium is recycled.

Such a circulating fluidized bed furnace can instantly dry and incinerate the combusted material, thereby maintaining the fluidized medium at a high temperature and enabling continuous combustion. In addition, since the fluid medium has a very large heat capacity, it is suitable for intermittent operation with little heat release during stoppage, and is also suitable for combustibles with a high water content such as sewage sludge.
The circulating fluidized bed furnace is provided with a plurality of burners for the purpose of raising the temperature or maintaining the temperature in the furnace. The burner 67 on the sand provided above the fluidized bed 62a and the sand provided in the fluidized bed 62a. There is a burner 68. Generally, the on-sand burner 67 is used at the time of temperature rise such as when the furnace is started up, and the in-sand burner 68 is used to maintain the temperature during normal operation in which a combustible material is charged and combustion is performed.

In a conventional general circulating fluidized bed furnace starting method, a fluid medium is supplied to the lower part of the riser, primary air is introduced from the primary air introduction port 65, and secondary air is introduced from the secondary air introduction port 66. Fluidize the medium. At the same time, the temperature of the fluid medium is raised by the flame of the burner 67 on the sand. In addition, the sand burner 67 is installed downward so that the flame goes to the fluidized bed. When the inside of the furnace is heated to a predetermined temperature and the auxiliary fuel can be ignited, the sand burner 67 stops. During normal operation, the auxiliary fuel is ejected by the sand burner 68 and burned to maintain the furnace temperature. .
As another starting method, Patent Document 2 (Japanese Patent Laid-Open No. 6-28111) discloses that a primary medium is raised to a predetermined temperature by a starting burner installed in a primary air duct, and a fluid medium is supplied by high-temperature primary air. A method for raising the temperature is disclosed.

  However, in the method in which the temperature is raised by the sand burner at the start-up, the fluidized fluid medium may collide with the sand burner and the sand burner may extinguish. Moreover, since the flame becomes unstable, CO is likely to be generated. Therefore, a method of preventing flame extinction by increasing the position of the burner on the sand and a method of reducing the blowing up of the fluidized medium by reducing the primary air amount can be considered, but in both cases, the amount of heat supplied to the fluidized bed is reduced Therefore, there is a problem that it takes time to increase the temperature of the fluid medium.

On the other hand, in various incinerators including the circulating fluidized bed furnace as described above, the combustion air used for the primary air and the secondary air is in the pit for storing combustibles such as sludge and dust in addition to the atmosphere. Odor gas is used. For example, Patent Document 3 (Japanese Patent Application Laid-Open No. 8-338619) discloses a configuration in which odor gas in a garbage pit is supplied into a furnace by a forced air blower and deodorized. This is intended to burn odor components by supplying odor gas into a high-temperature furnace.
However, when the incinerator has been stopped for a long period of time, flammable gas such as methane may be accumulated in the pit, and if the gas is introduced into the incinerator as a combustion gas at the time of start-up, there is a risk of explosion.

JP 2000-18538 A JP-A-6-28111 JP-A-11-82975

As described above, problems at the time of starting the circulating fluidized bed furnace include extinguishing the burner on the sand by blowing up the fluidized medium, or generating CO by destabilizing the flame. Further, if the amount of primary air is reduced so that the fluid medium does not collide with the burner on the sand, it takes time to raise the fluid medium, and there is a problem that rapid start-up cannot be performed. Moreover, in the method of raising the temperature of the primary air by the start burner as in Patent Document 2, there is a problem that the temperature rise in the furnace cannot be accurately performed while the temperature rise takes time because the primary air amount is limited. there were. Furthermore, as in Patent Document 3, when the odor gas in the pit is led into the furnace at the time of startup, there is a problem that safety cannot be ensured by the combustible gas accumulated in the pit.
Accordingly, in view of the above-mentioned problems of the prior art, the present invention prevents circulation of the burner on the sand due to blowing up of the fluidized medium or CO generation due to destabilization of the flame, and enables a rapid and stable start-up. It aims at providing the starting method of.

Therefore, in order to solve such a problem, the present invention forms a fluidized bed by fluidizing the fluidized medium with primary air introduced from the lower part of the riser, and also uses the primary air and secondary air introduced from above the fluidized bed. In the starting method of the circulating fluidized bed furnace in which the fluidized medium is blown up and discharged from the upper part of the riser together with the combustion gas, the fluidized medium is separated and collected from the combustion gas and returned to the riser.
A first burner provided above the fluidized bed and a second burner provided in the fluidized bed;
When starting up the circulating fluidized bed furnace, the first burner is ignited while the second burner is stopped, and the primary air amount and the secondary air so that the superficial velocity of the riser is less than 2.0 m / s. A first control step for controlling the amount of air;
The temperature inside the riser is measured, and when the temperature becomes equal to or higher than the self-combustion temperature of the fuel supplied to the second burner, the first burner is stopped and fuel is ejected from the second burner, and the empty And a second control step of controlling the primary air amount and the secondary air amount so that the tower speed becomes 2.0 m / s or more.

According to the present invention, when the sand burner is ignited at start-up, the superficial velocity is set to less than 2.0 m / s, thereby avoiding extinction due to collision of the fluid medium with the sand burner and stabilizing the flame of the sand burner. CO reduction is possible. Further, by raising the temperature with a low amount of air, cooling by air is avoided, and the temperature raising rate can be improved. Furthermore, NOx can be reduced by starting with a low amount of air.
On the other hand, after switching to the burner in sand, by increasing the superficial velocity to 2.0 m / s or more, it is possible to increase the heating rate by starting circulation of the fluid medium, and by increasing the amount of gas in the furnace, In the air preheater that heats the primary air and the secondary air with the exhaust gas of the circulating fluidized bed furnace, the amount of heat exchange is increased, and the temperature of the fluidized air is increased, thereby increasing the temperature rising rate. The self-combustion temperature is a temperature at which the fuel starts to burn without igniting the fuel.

In the first control step, the primary air amount is made smaller than the secondary air amount, and in the second control step, the ratio of the primary air amount to the secondary air amount is increased as compared with the first control step. It is characterized by that.
In this way, in the first control step, the primary air amount is set to a smaller value, so that the sand burner is prevented from extinguishing or the flame becomes unstable, the generation of CO at the start-up is reduced, and the sand burner is reduced. It is possible to reduce the frequency of misfires. Further, in the second control step, by increasing the increase amount of the primary air amount more than the increase amount of the secondary air, it is possible to promote fluidization of the fluid medium and to quickly raise the temperature.

The riser temperature is a fluidized bed temperature, and when the fluidized bed temperature reaches 600 ° C., the first control step is switched to the second control step.
In this way, by using the temperature of the fluidized bed in which the burner in the sand exists as a reference for switching between the first process and the second control process, the fuel ejected from the burner in the sand is surely self-burning from the burner on the sand to the sand. Can switch to medium burner. Further, by setting the switching temperature to 600 ° C., the sand burner is started at a temperature at which most types of fuels self-combust, and the furnace can be reliably started.

Further, the primary air and the secondary air are led from the atmosphere when the temperature in the riser is less than 800 ° C., and are led from the pit for storing the combustible when the temperature in the riser is 800 ° C. or more. It is characterized by having an odor gas.
Thus, when the fluidized bed temperature is less than 800 ° C, the odorous gas may not be burned completely and deodorization may be insufficient. Therefore, the odorous gas is burned only when the fluidized bed temperature is 800 ° C or higher. By using it as air, the odor component is completely burned and sufficient deodorizing treatment can be performed.

Furthermore, the combustible component concentration of the odor gas in the pit is measured, and when the measured combustible component concentration is equal to or higher than a preset lower explosion limit, the primary air and the second It is characterized by introducing the atmosphere as secondary air.
When the furnace has not been operated for a long time, the pit may be filled with flammable gas such as methane. Therefore, the concentration of combustible components in the pit is measured, and when the measured combustible component concentration is above the lower limit of explosion, the primary air or secondary air is supplied by always introducing the atmosphere into the furnace. It is possible to prevent explosion of combustible gas in the duct or in the furnace, and keep safety high.

As described above, according to the present invention, flame extinguishing due to the collision of the fluid medium with the burner on the sand is avoided, CO can be reduced by stabilizing the flame of the burner on the sand, and the rate of temperature rise is improved. Is possible.
In addition, by setting the primary air amount to a value smaller than the secondary air amount in the first control step, it is possible to prevent the burner on the sand from extinguishing and the flame from becoming unstable, and to reduce CO generation at startup. This makes it possible to reduce the frequency of misfires on the sand burner. Further, in the second control step, it is possible to quickly raise the temperature by making the increase amount of the primary air amount larger than the increase amount of the secondary air.

Furthermore, by using the temperature of the fluidized bed in which the burner in the sand exists as a reference for switching between the first process and the second control process, the switching from the burner on the sand to the burner in the sand is smoothly performed, and the switching temperature is set to 600 ° C. As a result, the sand burner can be started at a temperature at which most types of fuel self-combust, and the furnace can be reliably started.
Further, by using the odor gas in the pit as the combustion air only when the fluidized bed temperature is 800 ° C. or higher, the odor component is completely burned and sufficient deodorization treatment can be performed.
Furthermore, when the flammable component concentration of the odor gas in the pit is above the lower limit of explosion, the air is always introduced into the furnace, so that the primary air or the secondary air is supplied into the duct or the furnace. It is possible to prevent the explosion of flammable gas at high temperature and keep safety high.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.
The circulating fluidized bed furnace according to the present embodiment is a furnace that performs combustion treatment while mixing combustibles such as sewage sludge, municipal waste, industrial waste, and coal with a fluidized medium. It is suitably used for the treatment of sewage sludge.

  With reference to FIG. 1, the circulating fluidized bed furnace of this embodiment is demonstrated. In the figure, a circulating fluidized bed furnace 1 includes a riser 2 having a fluidized bed 2a formed by fluidizing a fluid medium such as silica sand filled in the furnace bottom, and a free board 2b positioned above the fluidized bed 2a. 2 is connected to the upper part of 2 and is connected to the cyclone 3 through the downcommer 4 for collecting the fluid medium blown up from the free board 2b and discharging the exhaust gas separated from the fluid medium to the flue, A seal pot 5 for preventing the unburned gas in the furnace from being blown into the cyclone 3 and a fluid medium return pipe 6 for returning the fluid medium stored in the seal pot 5 to the riser 2 are provided.

Combustible material input means 21 is provided on the furnace wall of the riser 2. The combustible material input means 21 is configured to input the combustible material received from the input hopper into the furnace in an appropriate amount by the supply feeder.
A primary air inlet 22 is provided at the bottom of the riser 2, and the fluidized medium is fluidized by the primary air introduced from the primary air inlet 22 to form a fluidized bed 2 a. A secondary air inlet 23 is provided in the riser furnace wall above the fluidized bed 2a, and the superficial velocity of the free board 2b is maintained by the secondary air introduced therefrom, and unburned in the combustion exhaust gas. The minutes are burned.
Air is guided to the primary air inlet 22 and the secondary air inlet 23 by the blowers 32 and 34, respectively, and the air flow rate adjusting valves 31 and 33 adjust the flow rate of air introduced into the respective inlet ports 22 and 23. Is done. Air introduced into the inlets 22 and 23 is heated by an air preheater (not shown) and heated to a predetermined temperature, and then introduced into the furnace through the inlets 22 and 23. The air preheater is a device that heats air with the heat of combustion exhaust gas discharged from the circulating fluidized bed furnace 1.

Further, a plurality of burn-up burners are provided on the furnace wall of the riser 2 in order to raise or maintain the temperature in the furnace. Among these, the sand burner (first burner) 24 is provided above the fluidized bed 2a and the nozzle tip is disposed downward, so that the flame from the sand burner 24 directly heats the fluidized medium of the fluidized bed 2a. It has become. A sand burner (second burner) 25 is provided in the fluidized bed 2a. The sand burner 25 is preferably disposed at a position where it is buried in the deposition layer of the fluid medium even when the primary air is not introduced and the fluid medium is not fluidized.
Auxiliary fuel such as methane gas (including digestion gas), city gas, and heavy oil is supplied to the sand burner 24 and the sand burner 25. The supply of this auxiliary fuel is adjusted by auxiliary fuel flow rate adjusting valves 35 and 36, respectively. Is done.

Moreover, the temperature measurement means 38 which measures the temperature of the fluidized bed 2a is provided. The temperature measuring means 38 is preferably a thermocouple. In this embodiment, the temperature in the furnace is the temperature of the fluidized bed 2a, but it may be another part in the riser, such as the temperature of the free board 2b. In that case, each temperature setting may be adjusted as appropriate.
Further, in the present embodiment, when the circulating fluidized bed furnace 1 is started, the primary air amount and the secondary air amount introduced into the furnace based on the temperature measured by the temperature measuring means 38 are set to the air flow rate adjusting valves 31, 33. And a control device 40 for controlling the start / stop of the sand burner 24 and the sand burner 25 by the auxiliary fuel flow rate adjusting valves 35, 36.

A starting method of the circulating fluidized bed furnace including the starting control by the control device 40 is shown in FIG.
First, a fluid medium is supplied into the riser 2, and the fluid medium is filled to a predetermined height (S1). The primary blower 32 is activated to introduce primary air into the furnace through the primary air introduction port 22, and the secondary blower 34 is activated to introduce secondary air into the furnace through the secondary air introduction port 23 (S2). . Then, the primary air amount and the secondary air amount are adjusted by controlling the air flow rate adjusting valves 31 and 33 so that the superficial velocity in the vicinity of the sand burner 24 in the riser 2 is less than 2.0 m / s (S3). .
At the same time, the auxiliary fuel flow rate adjusting valve 35 is opened to ignite the sand burner 24 (S4). The starting flow so far is defined as a first control step.

  The temperature is measured continuously or intermittently by the temperature measuring means 38 (S5), and it is determined whether or not the measured fluidized bed temperature is higher than a preset switching reference temperature (S6). The switching reference temperature is a predetermined temperature higher than the self-combustion temperature of the auxiliary fuel supplied to the sand burner 25, and this switching reference temperature is set in the control device 40 in advance. The self-combustion temperature is a temperature at which the auxiliary fuel starts to burn without igniting the auxiliary fuel. Preferably, the switching reference temperature is 550 to 650 ° C, more preferably 600 ° C.

When the fluidized bed temperature is lower than the switching reference temperature, the first control process is continued.
When the fluidized bed temperature is higher than the switching reference temperature, the auxiliary fuel flow rate adjustment valve 35 is closed to stop the fuel supply to the sand burner 24 and the auxiliary fuel flow rate adjustment valve 36 is opened to supply the sand burner 25 to the sand. Fuel supply is started and the burner 25 is activated (S7). At the same time, the primary air amount and the secondary air amount are controlled by the air flow rate adjusting valves 31 and 33 so that the superficial velocity becomes 2.0 m / s or more (S8).
Then, when the temperature in the furnace is raised to the combustion temperature, the start-up is terminated (S9), and the normal operation is started. The startup flow up to the previous stage before entering the normal operation is defined as the second control step. Note that the normal operation is an operation in which the inside of the furnace is maintained at a predetermined superficial velocity and combustion is performed by introducing a combustible. For example, the combustion temperature is 800 ° C.

Here, FIGS. 2 and 3 show specific examples of control of the superficial velocity and each air amount from the first control step to the second control step of the start control. FIG. 2 is a graph showing the superficial velocity with respect to the fluidized bed temperature, and FIG. 3 is a graph showing the primary air amount and the secondary air amount with respect to the fluidized bed temperature. Here, as an example, the switching reference temperature is set to 600 ° C.
As shown in FIG. 2, in the first control process in which only the sand burner 24 is activated, the superficial velocity is set to less than 2.0 m / s. Further, the primary air amount and the secondary air amount are controlled so that the superficial velocity gradually increases within the superficial velocity of less than 2.0 m / s.
In the second control step in which only the sand burner 25 is activated, the superficial velocity is set to 2.0 m / s or higher, and the superficial velocity is gradually increased so as to approach the superficial velocity during normal operation. . As shown in the figure, the rate of increase in superficial velocity is greater in the second control process than in the first control process. Although the superficial velocity is increased linearly here, it may be increased stepwise.

As described above, according to the present embodiment, when the circulating fluidized bed furnace 1 is started, the superficial velocity is set to less than 2.0 m / s when the sand burner 24 is ignited, so that the fluid medium collides with the sand burner 24. Flame extinguishing is avoided and CO reduction by stabilization of the flame of the sand burner 24 is enabled. Further, by raising the temperature with a low amount of air, cooling by air is avoided, and the temperature raising rate can be improved. Furthermore, NOx can be reduced by starting with a low amount of air.
On the other hand, after switching to the burner in sand, by increasing the superficial velocity to 2.0 m / s or more, it is possible to increase the heating rate by starting circulation, and by increasing the amount of gas in the furnace, primary air and The amount of heat exchange in the air preheater that heats the secondary air is increased, and the temperature of the flowing air is increased, so that the heating rate can be increased.

  Further, as shown in FIG. 3, in the first control step, the primary air amount is made smaller than the secondary air amount, and in the second control step, the primary air amount with respect to the secondary air amount is smaller than in the first control step. It is preferable to increase the ratio. In other words, in the first control process, the primary air amount is set to a smaller value, so that the sand burner 24 is prevented from extinguishing the flame or the flame becomes unstable, the generation of CO at the start-up is reduced, and the sand burner This makes it possible to reduce the frequency of misfires. Further, in the second control step, by increasing the increase amount of the primary air amount more than the increase amount of the secondary air, it is possible to promote fluidization of the fluid medium and to quickly raise the temperature.

FIG. 5 shows a circulating fluidized bed furnace to which the embodiment of the present invention is applied.
As an example, the combustible supplied to the circulating fluidized bed furnace 1 is sludge. The sludge collected by the transport vehicle is temporarily stored in the pit 50. The sludge in the pit 50 is transferred by a crane, discharged from the pit 50, and supplied to the circulating fluidized bed furnace 1. The odor gas in the pit 50 is sucked from the exhaust part 51 and guided into the furnace as primary air or secondary air, and burns in the furnace to be deodorized.

In this embodiment, the switching means 53 and 54 which switch the odor gas line led from the pit 50 to the furnace and the atmospheric line led from the atmosphere to the furnace are provided. The switching means 53 and 54 are controlled by the control device 40 based on the fluidized bed temperature measured by the temperature measuring means 38. When the fluidized bed temperature is lower than 800 ° C., the switching means 53 and 54 are switched to the atmosphere side to introduce the atmosphere into the primary air inlet 22 or the secondary air inlet 23. On the other hand, when the fluidized bed temperature is 800 ° C. or higher, the switching means 53 and 54 are switched to the odor gas side to introduce the odor gas from the pit 50 into the primary air introduction port 22 or the secondary air introduction port 23.
Thus, when the fluidized bed temperature is less than 800 ° C, the odorous gas may not be burned completely and deodorization may be insufficient. Therefore, the odorous gas is burned only when the fluidized bed temperature is 800 ° C or higher. By using it as air, the odor component is completely burned and sufficient deodorizing treatment can be performed.

Further, when the circulating fluidized bed furnace 1 has not been operated for a long period of time, since the fermentation of sludge proceeds in the pit 50, the pit 50 may be filled with a combustible gas such as methane. Therefore, when a methane concentration meter 52 for measuring the methane concentration in the pit 50 is installed and the measured methane concentration is equal to or higher than the lower explosion limit, the switching means 53 and 54 are switched regardless of the fluidized bed temperature. Always introduce the atmosphere into the furnace. Preferably, when the measured methane concentration is 25% LEL or higher, the atmosphere is introduced even when the fluidized bed temperature is 800 ° C. or higher.
Thereby, it is possible to prevent the explosion of the combustible gas in the duct for supplying the primary air or the secondary air or in the furnace, and to keep the safety high.

  In the present invention, when the circulating fluidized bed furnace is started, the burning of the fluid medium is prevented from extinguishing the burner on the sand or the generation of CO due to the destabilization of the flame is prevented, so that quick and stable starting is possible. It can be suitably applied to general circulating fluidized bed furnaces that incinerate combustibles such as industrial waste and coal.

It is a block diagram which shows the circulating fluidized bed furnace which concerns on embodiment of this invention. It is a graph which shows the superficial velocity with respect to fluidized bed temperature. It is a graph which shows the primary air quantity and secondary air quantity with respect to fluidized bed temperature. It is a flowchart which shows the starting control which concerns on embodiment of this invention. It is a block diagram which shows the circulating fluidized bed furnace to which embodiment of this invention is applied. It is a block diagram which shows the conventional circulating fluidized bed furnace.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Circulating fluidized bed furnace 2 Riser 2a Fluidized bed 2b Free board 3 Cyclone 5 Seal pot 22 Primary air inlet 23 Secondary air inlet 24 Sand burner (first burner)
25 Burner in sand (second burner)
31, 33 Air flow rate adjusting valve 32, 34 Blower 35, 36 Auxiliary fuel flow rate adjusting valve 40 Control device 50 Pit 51 Exhaust part 52 Methane concentration meter 53, 54 Switching means

Claims (5)

The fluidized medium is fluidized by the primary air introduced from the lower part of the riser to form a fluidized bed, and the fluidized medium is blown up by the primary air and the secondary air introduced from above the fluidized bed and discharged together with the combustion gas from the upper part of the riser. In the starting method of the circulating fluidized bed furnace in which the fluidized medium is separated and collected from the combustion gas and returned to the riser,
A first burner provided above the fluidized bed and a second burner provided in the fluidized bed;
When starting up the circulating fluidized bed furnace, the first burner is ignited while the second burner is stopped, and the primary air amount and the secondary air so that the superficial velocity of the riser is less than 2.0 m / s. A first control step for controlling the amount of air;
The temperature inside the riser is measured, and when the temperature becomes equal to or higher than the self-combustion temperature of the fuel supplied to the second burner, the first burner is stopped and fuel is ejected from the second burner, and the empty And a second control step for controlling the primary air amount and the secondary air amount so that the tower speed becomes 2.0 m / s or more.   In the first control step, the primary air amount is made smaller than the secondary air amount, and in the second control step, the ratio of the primary air amount to the secondary air amount is increased as compared with the first control step. The method for starting a circulating fluidized bed furnace according to claim 1.   The circulating fluidized bed according to claim 1 or 2, wherein when the temperature inside the riser is a fluidized bed temperature and the fluidized bed temperature reaches 600 ° C, the first control step is switched to the second control step. How to start the furnace.   The primary air and the secondary air are air derived from the atmosphere when the temperature inside the riser is less than 800 ° C., and the odor derived from the pit that stores the combustible when the temperature inside the riser is 800 ° C. or more. The method for starting a circulating fluidized bed furnace according to any one of claims 1 to 3, wherein the gas is gas.   The flammable component concentration of the odor gas in the pit is measured, and when the measured combustible component concentration is equal to or higher than a preset lower explosion limit, the primary air and the secondary air are used regardless of the temperature in the riser. The method of starting a circulating fluidized bed furnace according to claim 4, wherein the atmosphere is introduced.

Images