JP2002349821A - Combustion device and combustion method for solid fuel and method for remodeling pulverized coal fired boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent corrosion of a heat transfer pipe, increase a combustion gas temperature, increase thermal energy which can be recovered from a combustion device, and remodel a pulverized coal fired boiler into a boiler suitable for a multi-fuel combustion with the solid fuel and coal, in a method and a device to effect mixed combustion of solid fuel, containing much chloride, such as solid waste and biomass, and coal. SOLUTION: Solid fuel, such as solid waste and biomass, is burnt at a fluidized bed 11, situated at the lower part (the upper stream side) of a fuel device 10 at temperature lower than 800 deg.C suitable for desalting. Fuel, like coal, not containing much chloride is burnt at a powder combustion part 12 at the upper part (the downstream sided) of a combustion furnace.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to solid waste such as municipal waste and biomass such as wood and wood chips.
The present invention relates to a combustion apparatus and a combustion method suitable for mixing and burning a solid fuel containing a chlorine-based compound and coal, and a method for converting a pulverized coal boiler into a combustion apparatus suitable for mixed combustion with the solid fuel.

[0002]

2. Description of the Related Art Solid waste is household waste, business waste,
There are a wide variety of wastewater containing organic components treated in septic tanks of local governments and offices, and organic components processed in factories, such as packaging materials, old tires, waste cables, waste plastic materials, waste substrate materials, and the like. These solid wastes contain chlorine compounds and generate hydrogen chloride (HCl) by combustion. Hydrogen chloride corrodes heat transfer tubes. For example, Japanese Patent Publication No. 60-25179 discloses a method of removing hydrogen chloride by spraying quick lime (CaO) or slaked lime (Ca (OH) ₂ ) into the exhaust gas after burning to remove calcium chloride (CaCl _2). ) Shows a method of collecting with a filter. Limestone (CaC
The use of O ₃ ) is also well known.

[0003] Desalting agents include alkali metals (Na, K, L).
The oxides or carbonates of i) and alkaline earth metal oxides or carbonates are used. Generally, limestone, slaked lime, and quicklime which are compounds of alkaline earth metals are used.
The optimal reaction temperature for desalting agents such as calcium compounds is 45
When the temperature is high, the product after desalination such as calcium chloride is decomposed and chlorine is released as a gas. For this reason, about 8 combustion methods are suitable for desalination.
Fluidized bed combustion, which enables stable combustion at a temperature of 00 ° C. or less, is mainly used.

[0004] Biomass, such as wood and fir husks, is a renewable fuel using natural energy.
It is attracting attention as a fuel that can control the amount of carbon dioxide on the earth. However, biomass contains more halogens such as chlorides than coal. For this reason, when it is used as an alternative fuel to coal, immobilization of halogen elements such as chlorine, bromine, and fluorine becomes a problem. In addition, since the supply amount of biomass fuel varies from season to season, mixed combustion with coal (hereinafter referred to as co-firing) is desirable to obtain a constant power generation amount. In this case, a method of supplying biomass from the same burner as coal is common.

[0005]

In the above-mentioned prior art,
When using fluidized bed combustion when co-firing coal and solid fuel consisting of at least one of solid waste and biomass,
Since the temperature of the combustion gas is as low as about 800 ° C. or less, the steam temperature obtained by heat recovery is low, and the thermal efficiency cannot be increased. Further, when the solid fuel and coal are co-fired in the powder combustion (floating combustion) method used in ordinary coal combustion, the temperature of the combustion gas can be set to 1200 ° C. or higher, so that the thermal efficiency increases. However, halogen elements such as chlorine are released into gas from halogenated substances such as chloride contained in solid waste and biomass. The halogen element such as chlorine has a problem of corroding the heat transfer tube in the form of hydrogen chloride or the like. In order to suppress the concentration of hydrogen chloride in the combustion gas, for example, in the case of co-firing of biomass and coal, the proportion of biomass in the calorific value should be 5 to 5.
It must be limited to 10% or less.

SUMMARY OF THE INVENTION An object of the present invention is to fix and transfer halogenated substances such as chlorides contained in solid waste and biomass when co-firing coal with solid fuel comprising at least one of solid waste and biomass. An object of the present invention is to provide a combustion device and a combustion method that can increase the temperature of combustion gas around a heat transfer tube and increase thermal efficiency when reducing corrosion of a heat tube and obtaining thermal energy as steam from the combustion device.

Still another object of the present invention is to provide a combustion method for suppressing the generation of unburned components and dioxins in the fluidized bed combustion section and the powder combustion section.

Another object of the present invention is to convert a pulverized coal boiler to a boiler capable of mixing and burning pulverized coal with a solid fuel comprising at least one of solid waste and biomass. In fixing halogenated substances, such as chlorides, contained in the heat transfer tube, reducing the heat transfer tube corrosion, and obtaining heat energy as steam from the combustion device, the temperature of the combustion gas around the heat transfer tube was raised to improve the heat efficiency. It is an object of the present invention to provide a boiler conversion method that can be enhanced.

[0009]

According to the present invention, there is provided a combustion apparatus comprising: a fluidized bed combustion section for solid fuel comprising at least one of solid waste and biomass; and a fluidized bed combustion section provided downstream of the fluidized bed combustion section. It has a powder combustion unit of pulverized coal into which the combustion gas of the combustion unit flows, and a heat recovery unit provided downstream of the powder combustion unit and into which the combustion gas of the powder combustion unit flows. I do.

Chloride, which is contained in large amounts in solid waste and biomass, burns at a low temperature by fluidized bed combustion. At this time, an alkali metal or alkaline earth metal oxide contained in coal ash generated in the pulverized coal combustion section provided on the downstream side of the fluidized bed combustion and a desalting agent supplied into the fluidized bed, The chloride is desalted and discharged out of the fluidized bed as particles. Therefore, the amount of halogen elements such as chlorine contained in the combustion gas generated in fluidized bed combustion is small. Further, a fuel which does not contain a large amount of chloride, such as coal, is subjected to powder combustion at the upper part (downstream side) of the combustion furnace. Since the heat load can be higher in powder combustion than in fluidized bed combustion, the temperature of the combustion gas becomes higher (usually 1200 ° C. or higher). For this reason, the steam temperature of the heat transfer tube of the heat recovery unit can be increased, and the amount of recovered heat energy can be increased.

In the combustion apparatus according to the present invention, a separator for separating powder and combustion gas may be provided between the fluidized bed combustion section and the powder combustion section.

In the fluidized bed, chlorine fixed in the form of an alkali metal or alkaline earth metal chloride (eg, CaCl ₂ ) by a desalination reaction becomes a fine powder. Providing the separator makes it difficult for the powder generated by the desalination reaction to flow out of the fluidized bed into the powder combustion section. For this reason, the risk that the desalted chlorine is re-decomposed in the powder combustion section and causes corrosion of the heat transfer tube is reduced.

Further, the combustion apparatus of the present invention may have an air inlet for supplying air downstream of the powder combustion section. By injecting air stepwise from a powder combustion burner and an air inlet, the first half of the powder combustion section can be burned in a reduced state with insufficient air. In air-deficient combustion, the amount of nitrogen oxides at the outlet of the combustion device can be reduced because nitrogen oxides generated by the reaction of fuel and nitrogen in the air are reduced to nitrogen. In the latter stage of the powder combustion section, it is important to completely burn with air from the air inlet and to reduce unburned components and dioxins.

In the solid waste combustion apparatus according to the present invention, it is desirable that the temperature in the fluidized bed of the fluidized bed combustion section is adjusted to 800 ° C. or less. As the desalting agent, an oxide or carbonate of an alkali metal (Na, K, Li, or the like) or an oxide or carbonate of an alkaline earth metal is used. Generally, limestone, slaked lime, and quicklime, which are compounds of alkaline earth metals, are used. The optimum reaction temperature of a desalinating agent such as a calcium compound is 450 to 650 ° C. When the temperature is increased, a product after desalting such as calcium chloride is decomposed, and chlorine and the like are released as a gas. For this reason, it is necessary to reduce the temperature in the fluidized bed to 800 ° C. or lower in order to increase the burning rate and fix halogen elements such as chlorine.

As a method of reducing the temperature in the fluidized bed,
A method of drawing back a part of the combustion gas from the downstream of the heat exchange section of the combustion device and supplying the combustion gas to the fluidized bed combustion section, or cooling the fluidized medium to a flow path of the fluidized medium circulating between the fluidized bed combustion section and the outside. There is a method of providing a cooling unit that performs cooling.

Further, in order to suppress the emission of unburned components due to fluctuations in the combustion state in the combustion device, the amount of air supplied to the powder combustion step is determined by changing the temperature and brightness of the flame generated in the powder combustion step. , Shape can be adjusted based on the measurement result. Fuel ejected from the burner in the powder combustion section burns under a combustion gas atmosphere generated in a fluidized bed at the bottom of the combustion furnace. For this reason, even if fuel and air are ejected from the burner in a fixed amount, the temperature and brightness in the flame fluctuate due to fluctuations in the oxygen concentration of the combustion gas in the fluidized bed. By capturing the temperature variation and the brightness variation, the variation in the combustion state in the fluidized bed is captured, and based on the result, the amount of air supplied to the powder combustion process is adjusted, so that the oxygen concentration at the outlet of the combustion device is adjusted. Changes and the emission of unburned components can be suppressed.

[0017]

Embodiments of the present invention will be described with reference to the drawings. (First Embodiment) FIG. 1 is a schematic view of a combustion apparatus showing a first embodiment according to the present invention.

The combustion apparatus 10 has a fluidized bed combustion section 11 at the bottom.
Is provided with a powder burning section 12 at the top. 13 is an air inlet for feeding combustion air into the fluidized bed 11, 14 is a discharge pipe for extracting combustion ash and fluidized medium from the fluidized bed 11, 15 is a fuel inlet for the fluidized bed 11, 16 is a desalinating agent or fluidized medium. It is the entrance of. In addition, the fuel inlet 15 of the fluidized bed 11 and the inlet 16 of the desalting agent or the fluid medium may be the same inlet. Reference numeral 17 denotes a burner for powder combustion, reference numeral 18 denotes a combustion air inlet, and reference numeral 19 denotes a heat transfer tube provided at an upper portion of the combustion device.
In the heat transfer tube, water or steam is passed through, and the heat energy of the combustion gas is recovered by a steam turbine (not shown). The fuel is divided into a fuel hopper 20 containing chlorides such as solid waste and biomass and a fuel hopper 21 for coal. The fuel containing chloride is supplied from a fuel hopper 20 via a fuel supply port 22 via a fuel supply device 22. Fluidized bed combustion section 11
In addition to the fuel, a fluid medium and a desalinating agent are supplied from the hopper 23. Sand or the like is used as a fluid medium, and an oxide or carbonate of an alkali metal (Na, K, Li, or the like) or an oxide or carbonate of an alkaline earth metal is used as a desalting agent. Generally, limestone, slaked lime, and quicklime, which are compounds of alkaline earth metals, are used. Discharge pipe 1 below fluidized bed
A separator 24 for separating the fluid medium, the combustion ash, and the chlorides in the fuel is connected to the fluid medium 4, and the fluid medium and the unreacted desalinating agent are recovered and supplied again to the fluidized bed from the inlet 16.

The coal is supplied from the fuel hopper 21 to the fuel feeder 2.
5, The powder is supplied from the burner 17 for powder combustion through the crusher 26 together with a part of the combustion air into the combustion furnace. The combustion air is supplied from the supply blower 27 into the combustion furnace through the air inlet 13 at the lower part of the fluidized bed, the powder burner 17 at the upper part of the combustion furnace, and the air inlet 18. Usually, the amount of combustion air is 1.2 to 2 times the amount of air required for complete combustion of fuel in the entire combustion furnace. As shown in FIG. 2, the air inlet 18 of the combustion air is omitted, and the air is supplied from the supply blower 27 into the furnace through the air inlet 13 below the fluidized bed and the powder burner 17 above the combustion furnace. It is also possible to throw in.

In this embodiment, the fluidized bed 1 at the lower part of the combustion furnace
In 1, fuel supplied from the inlet 15 is burned at a temperature of 800 ° C. or lower. Further, the fuel supplied from the burner 17 provided in the powder burning section 12 in the upper part of the combustion furnace is burned at a temperature higher than the fluidized bed of about 1200 ° C. The fuel supplied to the fluidized bed 11 is solid waste such as municipal waste containing a large amount of chlorides, or biomass such as wood chips, wood, and rice hulls, and the fuel supplied from the burner 17 is chloride such as coal. It is characterized by using a fuel that does not contain a large amount of substances.

Chloride contained in solid waste and biomass is released into the gas as chlorine. This chlorine has the problem of corroding the heat transfer tubes in the form of hydrogen chloride. Therefore, in order to suppress the concentration of hydrogen chloride in the combustion gas, for example, in the case of co-firing of biomass and coal, it is necessary to limit the ratio of biomass in the calorific value to 5 to 10% or less.
On the other hand, as a method for removing hydrogen chloride from fuel, there is a method using a desalting agent. Alkali metals (N
a, K, Li, etc.) or an alkaline earth metal oxide or carbonate. Generally, limestone, slaked lime, and quicklime which are compounds of alkaline earth metals are used. The optimal reaction temperature of a desalinating agent such as a calcium compound is 450 to 650 ° C. When the temperature becomes high, the product after desalting such as calcium chloride is decomposed and chlorine is released as a gas. For this reason, fluidized bed combustion capable of performing stable combustion at about 800 ° C. or less is the mainstream as a combustion method suitable for desalination. At this time, since the temperature of the combustion gas is as low as about 800 ° C. or less, when the heat energy of the combustion gas is recovered as steam, the steam temperature is reduced and the thermal efficiency is reduced.

In the embodiment of the present invention, when fuels having different concentrations of chlorides contained in the fuel, such as solid waste and biomass and coal, are used, the above-described combustion method of each fuel is changed to change the above-described fuel. Try to solve the problem. That is, a fuel having a high concentration of chloride contained in the fuel, such as solid waste and biomass, is supplied to a fluidized bed provided at the lower part (upstream side) of the fuel furnace at a temperature of 800 ° C. or less suitable for desalination. Burn. For example, when quicklime is used as a desalting agent, desalting is performed by the following reaction.

CaO + 2HCl → CaCl ₂ + H ₂ O
Chlorine fixed in the form of an alkali metal or alkaline earth metal chloride, such as calcium chloride, is a fine powder. The immobilized chlorine is supplied to the outlet 1 at the bottom of the fluidized bed 11.
Extracted from 4. Further, a fuel which does not contain a large amount of chloride, such as coal, is subjected to powder combustion at the upper part (downstream side) of the combustion furnace. Since the heat load can be higher in powder combustion than in fluidized bed combustion, the temperature of the combustion gas becomes higher (usually 1200 ° C. or higher). At this time, the immobilized chlorine such as calcium chloride is decomposed when the temperature is increased, and chlorine is released. For this reason, the fluidized bed 11 and the burner in the combustion furnace have a sufficient space (usually 2 m or more), and even if the immobilized chlorine rolls up at the upper part of the fluidized bed, the high temperature as in the powder burning section 12 is maintained. It is desirable not to reach the region where

It is desirable that the amount of air supplied to the fluidized bed 11 is smaller than the amount of air required to completely burn the fuel supplied to the fluidized bed. By burning the fluidized bed 11 in a reduced state with insufficient air, the combustion reaction proceeds slowly. In the fluidized bed 11, local high-temperature portions may be generated due to uneven distribution of fuel and air. When a high temperature portion is formed, the fixation of chlorine by the desalting agent does not proceed, and the amount of hydrogen chloride released to the outside of the fluidized bed increases. By making the inside of the fluidized bed 11 short of air and burning slowly, generation of a high-temperature portion can be suppressed, and generation of hydrogen chloride can be suppressed.

Further, in order to suppress the temperature in the fluidized bed 11,
It is desirable to provide the cooler 31 in the circulation pipe of the fluid medium. By cooling the fluidized medium with the cooler 31, the temperature in the fluidized bed can be controlled to be constant. Further, as a method of controlling the temperature in the fluidized bed, there is a method of supplying a combustion gas cooled by a heat exchanger (not shown) downstream of the combustion device to the fluidized bed. The combustion gas has a low oxygen concentration and contains a large amount of carbon dioxide gas. Therefore, the heat capacity in the fluidized bed is increased by the supply of the combustion gas, so that the fluidized bed can be burned slowly.

The combustion gas generated in the fluidized bed 11 passes through the powder combustion section 12 in the upper part of the combustion furnace, so that the temperature of the gas rises. For this reason, the steam temperature in the heat transfer tube in the upper part of the combustion furnace can be increased as compared with the case of only fluidized bed combustion, and the heat energy that can be recovered can be increased. In addition, since air can be completely burned at a high temperature by the air supplied from the burner 17 and the air inlet 18 in the upper part of the combustion furnace, generation of unburned components such as carbon monoxide and dioxins can be suppressed.

Further, when using coal in powder combustion,
Part of the combustion ash generated by the combustion of the coal falls into the fluidized bed 11 at the lower part of the combustion furnace. The composition of the combustion ash varies depending on the type of coal. However, roughly, oxides of alkali metals and alkaline earth metals such as CaO and MgO are converted to ash having a weight of 5 to 1%.
Contain about 0%. The oxide of the alkali metal or alkaline earth metal in the combustion ash acts as a desalting agent in the fluidized bed 11. Therefore, the amount of the desalinating agent supplied can be reduced by burning the powder in the upper part of the fluidized bed and dropping the combustion ash into the fluidized bed.
Further, the combustion ash of coal is pulverized by being mixed with the fluid medium in the fluidized bed, and is easy to handle.

Fluidized bed combustion, as described above, tends to cause fluctuations in the oxygen concentration of the combustion gas due to variations in combustion, as described above. When the oxygen concentration in the combustion gas decreases, unburned components are emitted, and the thermal efficiency decreases. Also, when the amount of air is excessively increased, thermal energy that cannot be recovered as sensible heat of the combustion gas increases, and the thermal efficiency decreases. It is difficult to detect the state of combustion in a fluidized bed, and the temperature change is slower than that in powder combustion.
Further, even if the amount of air in the fluidized bed is changed, the diffusion speed of air in the fluidized bed is lower than in the case of powder combustion. For this reason, it is difficult to reduce the variation in the oxygen concentration by the method of controlling the supply amount of air due to the temperature variation in the fluidized bed.

In the embodiment of the present invention shown in FIG. 1, fluctuations in the oxygen concentration of the combustion gas in the fluidized bed are detected, and as a means for keeping the oxygen concentration at the combustion furnace outlet constant, the flame temperature of the fuel injected from the burner 17 is measured. Alternatively, it has a flame luminance measuring device 32 and a flow controller 33 for changing the amount of air supplied from an air supply port or a burner based on the measurement result.

The fuel injected from the burner burns in a combustion gas atmosphere generated in the fluidized bed 11 at the lower part of the combustion furnace. Therefore, even if the fuel or air is supplied from the burner 17 at a constant supply amount, the oxygen concentration of the combustion gas in the fluidized bed 11 fluctuates.
The temperature and brightness in the flame fluctuate. By capturing the temperature fluctuation and the luminance fluctuation, the fluctuation of the combustion state in the fluidized bed 11 can be detected. Normally, when the oxygen concentration of the combustion gas in the fluidized bed 11 decreases, the oxygen concentration also decreases in the powder combustion section 12 on the downstream side, so that the flame temperature and the brightness decrease. In particular,
Flame at the lower part of the powder combustion part 12 facing the fluidized bed 11 has a large fluctuation and is easy to detect.

By detecting the change in the oxygen concentration of the combustion gas generated in the fluidized bed 11 and adjusting the amount of air in the upper part of the combustion furnace,
The oxygen concentration at the combustion furnace outlet is kept constant, and the generation of unburned components can be suppressed. Further, since the fluctuation range of the oxygen concentration is reduced, it is not necessary to increase the amount of air more than necessary. For this reason, the amount of combustion exhaust gas and thermal energy that cannot be recovered as sensible heat can be reduced.

In order to suppress the increase of carbon dioxide on the earth, it is desirable to use renewable energy such as biomass or energy of waste such as solid waste. However, biomass and solid waste vary in seasonal supply. Another disadvantage is that the moisture content and the calorific value are not constant. Therefore, co-firing with coal can be considered for use in power generation. When remodeling the pulverized coal-fired boiler to co-firing with the solid waste and biomass, the lower part (upstream side) of the burner of the pulverized coal-fired boiler was remodeled, and FIG.
It is conceivable to provide the fluidized bed 11 as follows. At this time, since the heat transfer tubes and structures above (downstream) from the burner can be made the same as before the modification, the modification cost can be reduced.

(Second Embodiment) FIG. 3 is a schematic view of a combustion apparatus showing a second embodiment according to the present invention.

The difference from the combustion apparatus according to the first embodiment of the present invention shown in FIG. 1 is that the combustion furnace is separated into two parts, a fluidized bed 11 and a powder combustion part 12, and a particle is provided at the outlet of the fluidized bed. And a combustion gas separator 41 to supply only the combustion gas to the powder combustion unit 12.

In the fluidized bed, the chlorine fixed in the form of a chloride (for example, calcium chloride) of an alkali metal or alkaline earth metal by a desalination reaction becomes a fine powder. FIG.
By providing the separator 41 as described above, the powder generated by the desalination reaction hardly flows out of the fluidized bed into the powder combustion unit 12. For this reason, the danger that chlorine desalted in the fluidized bed due to high-temperature combustion in the powder combustion section 12 is re-decomposed and causes corrosion of the heat transfer tube is reduced.

In the case of remodeling work for co-firing solid waste and biomass in a pulverized coal boiler, heat transfer tubes, which are pressure pipes, are routed around the combustion furnace wall. Often becomes. By separating the fluidized bed as shown in FIG. 3, there is no need to take measures against abrasion of the heat transfer tubes in the fluidized bed compared to the case where the fluidized bed is provided in the combustion furnace as in the combustion furnace shown in FIG. For this reason, the remodeling part of a combustion furnace can be reduced.

[0037]

According to the present invention, in a combustion method and a combustion apparatus for co-firing coal with solid fuel containing a large amount of chloride such as solid waste and biomass, corrosion of a heat transfer tube or the like by chloride is prevented, and In addition, the temperature of the combustion gas can be increased, and the heat energy that can be recovered from the combustion device can be increased.
Further, the pulverized coal boiler can be modified into a combustion device suitable for co-firing with the solid fuel.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a combustion device according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a combustion device according to another embodiment of the present invention.

FIG. 3 is a schematic configuration diagram of a combustion device according to still another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Combustion apparatus, 11 ... Fluidized bed combustion part, 12 ... Powder combustion part (floating combustion part), 13, 18 ... Air inlet, 14 ... Discharge port, 15 ... Fuel inlet, 16 ... Desalinating agent and fluid Medium inlet, 17: burner for powder combustion, 19: heat transfer tube, 20,
21: fuel hopper, 22, 25, 28: fuel supply device, 2
3: hopper, 24, 41: separator, 26: crusher, 27
... supply blower, 31 ... cooler, 32 ... measuring instrument, 33 ... flow controller, 42 ... flame.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masayuki Taniguchi 7-2-1, Omika-cho, Hitachi City, Ibaraki Prefecture Inside Power and Electricity Research Laboratory, Hitachi, Ltd. (72) Inventor Kenji Yamamoto Omika-cho, Hitachi City, Ibaraki Prefecture 7-2-1, Hitachi, Ltd. Electric Power and Electric Development Laboratory (72) Inventor Shunichi Tsumura 6-9 Takara-cho, Kure-shi, Hiroshima Babcock-Hitachi Kure Factory (72) Inventor Yoshitaka Takahashi, Kure, Hiroshima No. 6-9, Ichitakacho B terminus in the Kure factory of Babcock Hitachi Co., Ltd. F term (reference) 3K062 AA11 AB01 AC01 AC17 BA02 CA01 CB03 DA01 DA05 DA40 DB08 3K064 AA04 AA08 AA10 AB01 AC02 AC06 AC10 AC12 AD05 AD08 AE01 AE04 AE06 AE11 BB07 3K065 AA11 AB01 AC01 AC17 BA01 JA05 JA18

Claims (11)

[Claims] 1. A fluidized bed combustion section for solid fuel comprising at least one of solid waste and biomass, and pulverized coal provided downstream of the fluidized bed combustion section and into which combustion gas from the fluidized bed combustion section flows. An apparatus for burning solid fuel, comprising: a powder combustion unit; and a heat recovery unit provided downstream of the powder combustion unit and into which combustion gas from the powder combustion unit flows. 2. A fluidized bed combustion section for solid fuel comprising at least one of solid waste and biomass; a separator for separating powder and combustion gas downstream of the fluidized bed combustion section; A powder combustion unit for pulverized coal provided on the downstream side, and a heat recovery unit provided on the downstream side of the powder combustion unit and into which the combustion gas of the powder combustion unit flows; A solid fuel combustion apparatus, wherein the separated powder is returned to the fluidized bed combustion section. 3. An air inlet for supplying air to a downstream side of the powder combustion section.
The combustion device according to claim 1. 4. The solid fuel combustion according to claim 1, wherein the fluidized bed combustion section has a combustion exhaust gas inlet for supplying a part of the combustion gas discharged from the heat recovery section. apparatus. 5. The fluidized bed combustion section has a flow path for circulating a fluid medium with the outside of the fluidized bed combustion section, and the flow path has a cooling section for cooling the fluid medium. The solid fuel combustion device according to claim 1 or 2, wherein: 6. A fluidized bed combustion of a solid fuel composed of at least one of solid waste and biomass, and a powder combustion process of burning pulverized coal using a combustion gas of the fluidized bed combustion process. A method for burning solid fuel, characterized in that: 7. The method according to claim 6, wherein an oxide of an alkali metal or an alkaline earth metal is used as a fluid medium in the fluidized bed combustion step. 8. The method for burning solid fuel according to claim 6, wherein the temperature of the combustion gas in said fluidized bed combustion step is adjusted to 800 ° C. or lower. 9. The combustion method according to claim 6, wherein an amount of air supplied to the powder combustion step is determined based on a measurement result of any one of temperature, brightness, and shape of a flame generated in the powder combustion step. A method for burning solid fuel, comprising adjusting. 10. A boiler modification method for modifying a pulverized coal boiler into a mixed combustion boiler of pulverized coal and solid fuel comprising at least one of solid waste and biomass, wherein a fluidized bed combustion zone is provided at the bottom of the pulverized coal boiler, A method for remodeling a boiler, wherein a supply port for supplying a solid fuel such as solid waste or biomass, an oxide of an alkali metal or an alkaline earth metal, a fluid medium, and combustion air is provided in the fluidized bed combustion zone. 11. A boiler modification method for modifying a pulverized coal boiler into a mixed combustion apparatus of pulverized coal and solid fuel comprising at least one of solid waste and biomass, wherein a fluidized bed combustion furnace is provided upstream of the pulverized coal boiler. A powder and combustion gas separator is provided between the fluidized bed combustion furnace and the pulverized coal boiler, the powder discharged from the separator is returned to the fluidized bed combustion furnace, and the combustion gas discharged from the separator is fine powder. A method for remodeling a boiler, comprising providing a supply port for supplying from a burner of a coal boiler from an upstream side.