JPS61105007A - Fluidized bed type combustion method and combustion mechanism - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a fluidized bed combustion method and combustion mechanism, and is useful for effectively burning solid or liquid fuel, particularly while suppressing nitrogen oxides.

(Prior Art) Combustion devices that use a fluidized bed to burn coal containing sulfur have already been proposed. In this conventional combustion apparatus, the fluidized bed uses the so-called bubbling fluidized bed method (bubbly fluidized bed method).
The surface flow velocity of this fluidized bed is 4 to 12 feet/second.
(approximately 120 to 3600%/sec), and the average particle size is approximately 10
It is made up of 00 micron particles. Coal particles are burned in a fluidized bed, and limestone or dolomite absorbents are added to the fluidized bed to reduce the release of sulfur oxides. This absorbent is added to the fluidized bed as particles with a particle size of 1000-3000 microns, and the fluidized bed mainly contains coal ash9 reacted absorbent, partially reacted absorbent and partially burned fuel particles. It will be done. In addition, a tube is installed in the fluidized bed to transfer heat to the steam, and another tube is installed above the fluidized bed to remove heat from the combusted hot gas and lower the temperature of the hot gas. ing. During combustion, particulates of charcoal, ash, and partially reacted absorbent are released from the fluidized bed. Most of these particulates are transferred to the recirculating cyclone downstream of the convection heat exchanger to completely burn out the fuel particles and the unreacted absorbent absorbs the sulfur oxides more effectively. It is then captured and returned to the fluidized bed. It is provided that only the finest particles are emitted from the cyclone and sent to the filter device where they are captured. Further, the flow rate in the recirculation path is set to be approximately equal to the total flow rate of the solid content of the fuel and absorbent supplied into the combustion device.

(Problems to be Solved by the Invention) However, the conventional combustion apparatus described above has several problems. First, unburned fuel particulates were released from the combustion device, and the combustion efficiency was reduced to about 97X. This became extremely noticeable when burning a fuel with a low volatile component such as petroleum coke with a carbon content of 9ON compared to coal with a carbon content of 42X. Absorbent utilization is also low, requiring a molar ratio of calcium to sulfur of at least 3 to meet the requirements of normal air pollution regulations.
It was necessary to maintain a ratio of 1:1 and suppress sulfur oxides by 90%. Therefore, although sulfur oxides were absorbed on the surface of the absorbent particles by a relatively large amount of the absorbent particles, most of the absorbent inside the particles was released in an unused state. Furthermore, the combustion equipment was emitting nitrogen oxides, which are produced from the nitrogen contained in the fuel and pollute the atmosphere. In this case, the amount of nitrogen oxides released exceeded the regulatory level in Southern California, which has high regulatory limits.

On the other hand, in order to improve the combustion efficiency of combustion equipment, US Pat.
, 177.741 proposes a method of agglomerating recycled fine particles before introducing them into a bubbling fluidized bed. In this case, the agglomerated fine particles are effectively prevented from flowing into the fluidized bed, so that combustion within the fluidized bed is enhanced. In addition, in U.S. Patent No. 4,259°911, in a fluidized bed (=
A configuration for agglomerating coal particulates and recycled particles prior to fuel injection is disclosed, and US Pat.
, 329.

In No. 234, in order to increase the utilization rate of the absorbent, a part of the fluidized bed is omitted and the absorbent is crushed to a particle size of 50 microns to increase the surface area of the absorbent, thereby increasing the absorption rate of sulfur oxides. Disclosed. In this case, the finely divided absorbent particles are aggregated with coal (fuel) particles and reintroduced into the fluidized bed. However, all of these configurations only improve the details of the fluidized bed combustion apparatus, and have not sufficiently suppressed the above-mentioned problems, particularly nitrogen oxides.

Furthermore, German Patent No. 3,023,480 discloses another arrangement for increasing the utilization of the absorbent and suppressing sulfur oxides originating from the combustion gases. In this case, the combustion gas has a particle size of 3
It is passed through a fluidized bed containing absorbent particles of 0 to 200 microns and whose surface velocity is 3 to 30 feet/second (approximately 90 to 900 m7 seconds), and the particle density of the fluidized bed is adjusted to 0.1 to 10 KP/second.
Make it m2. Particles contained in the high flow rate gas are removed by a cyclone, and the temperature is 1300-2000'lt.
' (approximately 704 DEG -1093 DEG C.) and the recirculation flow rate per hour is approximately 5 times that of the overlapping fluidized bed. According to this configuration, sulfur oxides can be suitably suppressed using fine particles that have a large surface area and are actively mixed.
The technical idea of arranging cooling pipes in the fluidized bed to recover heat had not yet been reached.

U.S. Pat. No. 4,111,158 also discloses an arrangement for enhancing fluidized bed combustion efficiency and suppression or removal of sulfur oxides and nitrogen oxides. In this case, the surface flow velocity of the bubbling fluidized bed is 4 to 12 feet/sec, and the upper surface of the bubbling fluidized bed is clearly demarcated, and the surface flow velocity of the connected fluidized bed is 15 to 45 feet/sec. / second (approx. 450~1350@
/sec), and the top surface of the continuous fluidized bed is not clearly demarcated, and the particle density changes gradually from the bottom to the top of the combustion device.

Particles contained in the gas stream within the combustion device are separated by a recirculation cyclone located downstream of the combustion device and reintroduced into the fluidized bed. Particle sizes range from 30 to 250 microns and particle densities range from 10 to 40 Ky/m'' at the top of the combustor. In this case no heat is recovered from the particles and gases in the combustor and recirculation path, and The inner tubes are susceptible to erosion, and the particle density is low compared to that of the bubbling fluidized bed (500 Ky/m''), so there is no effective heat transfer. Heat is therefore recovered by removing a portion of the fluidized bed from the bottom of the combustion device and cooling it in a suitable heat exchanger. High combustion efficiency is achieved through complete combustion of well-mixed, small-diameter fuel particles in the combustor and recirculation path. Absorbent utilization is increased by using fine absorbent particles and maintaining temperatures at effective levels throughout the combustion device and recirculation path. Also, by sequentially introducing combustion air over the entire length of the combustion device, the generation of nitrogen oxides can be suppressed. However, this combustion apparatus particularly requires a separate heat exchanger containing a fluidized bed, and also has problems in that it requires a large recirculation cyclone.

US Pat. No. 3,900,554 discloses a structure in which ammonia is injected without using a catalyst to suppress nitrogen oxides. In this case, the basic gas reaction of ammonia
Nitrogen oxides can be reduced as desired at 00°O), when the molar ratio of ammonia to nitrogen oxides is 2
It is said that it will be suppressed by 0%. On the other hand, when the molar ratio of ammonia to nitrogen oxides is likewise 2, as in a recirculating cyclone, good mixing is obtained;
It was not possible to generate 95% of nitrogen oxide ions.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a fluidized bed combustion method and combustion mechanism that achieves high combustion efficiency without using a separate heat exchanger incorporating a fluidized bed or a large recirculation cyclone.

(Means for Solving the Problems) According to the present invention, the above object is achieved by providing a combustion apparatus having a bubbling fluidized bed, in which heat transfer pipes are disposed, and particles of the fluidized bed are provided. The average particle size of the fluidized bed is within the range of 100 to 800 microns, 20 to 40% of the particles have a particle size smaller than 200 microns, and the surface flow velocity of the fluidized bed is 3 to 7 feet/1. (approximately 90 to 210 feet/second), which is sufficiently lower than the flow rate of 15 to 45 feet/second in the rest of the fluidized bed, and the relatively small surface flow velocity in one part of the layer consisting of small-diameter particles. A bubbling fluidized bed is produced by increasing the discharge flow rate of the particulate components, preferably with a particle density of 0.5 and 7 m3 in the upper part of the fluidized bed,
Adopt a configuration that coexists with the normal value 10 to 4 Q K9/m3 of the other part of the fluidized bed (20 to 4 is achieved).

(Function) In the present invention as described above, the surface flow velocity is extremely low even though the particle size is the same as that of the other part of the fluidized bed, so the particles are moved extremely small, and this has a remarkable effect of obtaining a good bubbling fluidized bed. can be realized.

In addition, according to the present invention, since the average particle size is extremely small (500 microns vs. 1000 microns) compared to the conventional bubbling fluidized bed combustion device, the moving speed can be considerably increased. Since there is no heat transfer surface to cool the gas and particles between the fluidized bed and the recirculation cyclone as in the prior art, an isothermal recirculation path can be created that operates at the ideal temperature during combustion or sulfur absorption. In the present invention, unlike conventional fluidized bed combustion equipment, ammonia is injected at the inlet of the cyclone, so the release of nitrogen oxides can be extremely effectively suppressed.Also, the particle size of particles in the fluidized bed can be reduced. Therefore, the heat transfer coefficient of the pipes installed in the fluidized bed (2) can be increased by 100 to 300 K, and the corrosion of the pipes can be reduced by lowering the tile surface flow velocity (the corrosion of the pipes is an exponential function of the surface flow velocity). increase).

(Example) The drawing shows a combustion mechanism according to the present invention comprising a combustion device (101) for combustion of a fluidized bed.The combustion device C1l includes a combustion chamber (111), and the combustion chamber αυ is It is configured to form a fluidized bed B made of particles on a distribution plate α2 disposed therein.

In addition, the combustion chamber (111) of the combustion device α [includes a cooling pipe located in the fluidized bed B, a fuel supply path I, and a fluidized bed outlet path (L61). Furthermore, the combustion chamber (
A fluidizing air inlet αD is provided at the bottom of 111, through which air for fluidizing particles is introduced. The hot gas and fine particles released from the surface of the fluidized bed B are sent to the recirculation cyclone (211) disposed above the fluidized bed through the freeboard section (1) and the conduit α2.

The linear intrusion leg extending downward from the cyclone (211) is sufficiently long to allow the fine particles to return smoothly to the fluidized bed.In this case, the point of the cyclone (21) is approximately 1
It is 2 microns.

To suppress nitrogen oxides produced when fuel is combusted with nitrogen, ammonia is injected into the hot gas stream flowing in conduit σ9 from an ammonia injector (c) located immediately upstream of the cyclone (21). . Ammonia is supplied from the ammonia supply tank (2) to the ammonia injector (c).

The hot gas is sent to the convection type heat exchanger (c) through the cyclone ■υ or conduit, and the heat is absorbed from the hot gas in the heat exchanger (c). The hot gas from which the heat has been removed is transferred to a heat exchanger (
) to filter devices such as baghouse filters (
5), where the dust is removed and released into the atmosphere from the chimney.

More specifically, in the fluidized bed combustion method and combustion apparatus of the combustion mechanism according to the present invention, the surface flow velocity of the bubbling fluidized bed B is O.S~7 ft/sec (about 15~210 Gl
/sec), and the particle diameter of fluidized bed B is 45~
2000 microns and fluidized bed B
40-20X of the particles are each smaller than 200 microns in diameter. The refractionally large particles in the particles of fluidized bed B depend on the size of the dolomite feedstock used.

In addition, heat is partially removed from the fluidized bed B through a cooling pipe α3 arranged in the high temperature fluidized bed B, and the heat transfer coefficient outside the cooling pipe (13) is different from that inside the fluidized bed B. Since it consists of fine particles, 100 to 200 BTU/FT2・)ll'
t-F (petiny per hour square foot degree F, IB
TU/FT2・HR-F =0.2048 xca1/
solid or liquid fuel is fed directly into the flow Jtj B.

A sulfur absorbent such as limestone or dolomite is also fed directly into fluidized bed B.

The freeboard part αa of the combustion chamber αD of the combustion device (Lα) is heated to a high temperature and is not provided with a heat transfer surface.A large amount of fine particles are released from the fluidized bed B to the freeboard part αa, and the hot gas and fine particles are mixed. In this state, it remains in the freeboard area (1υ) for a sufficiently long time and a chemical reaction occurs.

Most of the particles released from the fluidized bed B to the freeboard section (181) are returned to the fluidized bed B, but a large amount of particles are sent to the cyclone CI!υ along with the hot gas flow, and It is separated from the hot gas and returned to the fluidized bed B at substantially the same temperature.The amount of fine particles contained in the hot gas introduced into the cyclone is approximately 0.5 to 5I/
About 11L2 teal. 7! By thoroughly mixing fine coal particles and combustion gas containing a large amount of oxygen in the l-bow 1' section (181 and cyclone circle) and allowing them to stagnate for a sufficiently long time, the coal particles in the mixture are completely removed. It is burned and released from cyclone C11.

These charcoal particles reduce nitrogen oxide formation down to 1400°F.
Similarly, in the freeboard section (181 and cyclone (2il) the sulfur oxides and fine absorbent particles contained in the combustion gases are sufficiently The sulfur oxides are properly captured by the absorbent by being thoroughly mixed and retained for a long time. At 211, it takes about 3 seconds.

Cyclone (21) has a dropping point of 5 microns and an intrusion leg @
through which the majority of particles substantially larger than 5 microns are smoothly recycled to the fluidized bed B, and the emission of particles larger than 5 microns from the filter device can be prevented. The flow rate of particles trapped in the recirculation process is about 20 times higher than the flow rate at which the mixed flow of fuel and absorbent is fed into fluidized bed B.
If the flow rate is doubled, the flow rate per hour will be twice the weight of the fluidized bed B.

If the fuel contains nitrogen combined with the fuel and it is necessary to suppress nitrogen fluoride, ammonia is injected into the combustion hot gas stream immediately upstream of the inlet of the cyclone (2υ). Without using, 1743-1832'?
Nitrogen oxides can be reduced with maximum efficiency as desired in the range of 1:1 ammonia within the range of 1450-1650°F (approximately 788-89°C).
By operating the fluidized bed B at a temperature of 9°C) and bringing the temperature at the top of the fluidized bed B after combustion to 0~150＠F (approximately -18~66°C), nitrogen oxides can be further reduced effectively. Ru.

When ammonia is injected so that the molar ratio of ammonia and nitrogen oxides is 1.5:2, a cyclone (2
Since good mixing is obtained within 1 J, nitrogen oxides are suppressed by 80-95%. Under certain conditions, nitrogen oxides can be suppressed without ammonia injection. That is, when combustion temperatures are lowered to as low as 1450 degrees Fahrenheit (about 788 degrees Celsius) and the fuel contains a certain high percentage of carbon, most of the recycled particles are charcoal particles. In the present invention, special features (:
These carbon particles suppress 86% of nitrogen and reduce nitrogen oxides.

The hot combustion gas and dust released from the Nylon Re J are sent to a convection type heat exchanger (c), where heat is removed from the hot gas and the hot gas is cooled to the release temperature. Finally, the hot gas is sent from the heat exchanger (c) to the filter device (5), where dust is removed and released into the atmosphere.

In this case, the present invention uses various solid and liquid fuels, including those that are difficult to combust (e.g. low-volatile petroleum coke containing 90% carbon), or fuels containing sulfur, nitrogen and mixtures thereof (all of which are air pollutants). The goal is to burn cleanly. Therefore, according to the present invention, fuel is combusted using a bubbling fluidized bed B consisting of fine particulate components while recirculating most of the particulates through the hot gas recirculation path. 90% carbon
Using petroleum coke, the molar ratio of calcium/a yellow was set to 1.
When set to 8, the combustion efficiency is 99.4. %, 98% of sulfur oxides were suppressed. The ammonia/nitrogen molar ratio is 2
．． 95 when 0. % of nitrogen oxides were suppressed. These results were all obtained by burning with the same combustion mechanism.

Another feature of the invention is to increase the fluidization range, such as up to 15:1. Since the fluidized bed B is composed of fine particles, the minimum fluidization speed of the fluidized bed B is about 0.5 foot/second (about 15 alI/second).

Experimental Example 1 (When petroleum coke is used) Petroleum coke was combusted in air in the combustion chamber αυ of a combustion apparatus αα having the configuration shown in the drawing. The combustion chamber aυ is of fireproof construction and has a diameter of 3 feet (approximately 90 mm) and a height of 12 feet (approximately 36 mm).
0 m), and a cyclone r is installed at the top of the combustion chamber αυ.
2I) was installed. The depth of the fluidized bed B was 31/2 to 4 feet (approximately 105 to 120 feet), and heat transfer pipes (13) were installed in the fluidized bed B. And the calorific value is as shown below.

Carbon 89.7% by weight Elements 1.9% by weight Sulfur 2.1% by weight Other volatiles 4.4% by weight Ash 0.3 weight JILx Moisture 1.6% by weight Calorific value (HHI 14.270BTU/LB( Biteil per bond, IBTU/LB= T-cho KcalΔ
9) This petroleum coke has little volatile content, so it is difficult to burn.
<Contains nitrogen and sulfur, which generate nitrogen oxides and sulfur oxides as air pollutants. This petroleum coke was introduced into the fluidized bed B through the fuel supply channel (141), and the particle size of the fuel was mostly in the range of 50 to 400 microns.
51 into the fluidized bed.

The components of dolomite are as follows.

Carbonation power #Sium 56,6 (5-53,6) Weight x Magnesium carbonate 45.5 (~43,5) Weight x Inert ingredients 0.9% by weight Dolomite particle size is 47
The reeds were burned in the fluidized bed B in the form of fine particles in the range of 0.00-1200 microns.

Fluidized bed B initially contained dolomite with an average particle size of 800 microns.

After approximately 500 hours of combustion, the average surface of fluidized bed B (containing natural, old and partially aged absorbent, with an average particle size of approximately 300 microns) The flow rate was 4 feet/second (approximately 1,200,717 seconds), and it was necessary to periodically maintain fluidized bed B to keep the average surface flow rate at a constant level.

In the cyclone circle, most of the combustion chamber space is occupied by particles larger than 5 microns, and by providing an infiltration leg device, the particles can be freely collected into the fluidized bed B with virtually no resistance. was designed to be As a result, the recirculation flow rate of fine particles was large, and the recirculation flow rate per hour was twice that of the overlapping fluidized bed B and 20 times the solid content supply flow rate. The fuel particles and absorbent particles did not leave the fluidized bed B along with the gas flow until they became extremely small in size, and were held within the fluidized bed B and fragmented by the action of the fluidized bed B. With the combustion chamber (111), even difficult-to-burn fuel containing about 90% carbon was completely combusted with high efficiency. Combustion efficiency could be further increased by keeping the temperature isometric with the recirculation path.Fuel particles were placed in the fluidized bed B The temperature of the fluidized bed B was set to 1600'? (approximately 871
”O) 1m x 20~30x (7) When combustion was performed with excess air, the combustion efficiency was 99.4X. In this case, the temperature above the fluidized bed B after combustion was 50~100＠F (approximately 1
0 to 38'O).

By dividing and retaining the absorbent particles, the surface area of the absorbent becomes large, and sulfur is absorbed from the gas in the combustion chamber (lυ).When the molar ratio of calcium to sulfur is 1.8, 98 % of sulfur oxides was suppressed. Combustion chamber (l
Because the particle size in D is fine, the heat transfer coefficient on the surface of the tube disposed in fluidized bed B has been increased.The heat transfer coefficient on the surface of this tube is 40 to 60 BT
U/HR-F'r2- F was 100~
It became 200 BTU/HR-FT2-F.

In order to suppress the emission level of nitrogen oxides in order to pass air pollution regulations in Lufhornia, southern United States, ammonia (NH3) is injected upstream of the cyclone (21), mixed with combustion gas, and reacted to produce nitrogen oxides (NH3). NO)
was converted into nitrogen and water. When the molar ratio of NH3 and No was set to 2, about 95% of No was suppressed.

Coal from Utah was soot-roasted in the same manner using the same combustion chamber αD as in Experimental Example ①. The components and calorific value of this coal are as follows.

Carbon 43% Nitrogen 1.3X; Sulfur 0.6x Other volatiles 37.1. %” Ash content 8.Oy Moisture 10.OX Calorific value 11,500 BTU/LB Utah state-grade coal has a much lower carbon content and a higher volatile content, so it was easier to burn than petroleum coke.Utah. The size of state coal was less than 15/8 inches (4,126).

The same dolomite as in Experimental Example I was used as the sulfur absorbent, and its components were as follows.

Lucicum carbonate 56.6 (~53°6) weight x magnesium carbonate 45.5 (~43.5) weight x inert ingredients 0.9 *fmx Dolomite grain size ranges from 1,200 to 4,700 microns It was burned in the form of fine particles in the fluidized bed B.

When this coal is combusted with 20X excess air, the combustion efficiency is 998x and the temperature of fluidized bed B is 1600'y (
It was approximately 87 picoC). Also, in the case of this coal, only 20
1400°F (approximately 760°a
) and had good combustion characteristics.

For petroleum coke, the desired combustion characteristics can be achieved at 1450°F (approximately 78°F) only by increasing the excess air to 60%.
The temperature could be maintained at 8'O).

The fuel is coal and the fluidized bed B temperature is 1600″F (approximately 871″
In the case of C), the afterburning in the upper part of the fluidized bed B is 10 to 2
The temperature was reduced to 0°F (approximately -12 to -6.7"O). In this experimental example as well, sulfur oxides and nitrogen oxides were suppressed as in the case of petroleum coke.

(Effects of the Invention) According to the present invention configured as described above, the configuration is sufficiently simplified, and even in petroleum coke with particularly low volatile components, the generation of nitrogen oxides is significantly suppressed, and the To achieve effective effects such as achieving complete combustion with high combustion efficiency.

[Brief explanation of drawings]

The drawing is a simplified explanatory diagram of a combustion mechanism equipped with a combustion device according to the present invention.

Claims (11)

[Claims] (1) Supplying solid fuel into a fluidized bed combustion device and forming a fluidized bed containing inert particles, ash particles, and partially burned fuel particles with an average particle size within the range of 100 to 800 microns. a step in which a fluidized bed is operated at a surface velocity of 0.5 to 7 ft/sec (approximately 15 to 210 cm/sec) to release a significant amount of particulates from the fluidized bed, and the particles contained in the exhaust gas from a combustion device. is captured in a recirculation cyclone and returned to the fluidized bed at a return flow rate of 1 to 5 times the weight of the fluidized bed per hour, and from the pipes arranged in the fluidized bed and the exhaust gas stream downstream of the cyclone. a process of recovering heat;
Collecting dust from a cooled exhaust gas stream. (2) Supplying an absorbent for sulfur oxides into the combustion device at the same time as the fuel, and inert particles, ash particles, partially burned fuel particles and portions having an average particle size within the range of 100 to 800 microns. A fluidized bed combustion method according to claim 1, comprising the step of forming a fluidized bed containing absorbent particles for reacted sulfur oxides. (3) A fluidized bed combustion method according to claim 1, comprising the step of introducing ammonia into the combustion hot gas stream immediately upstream of the recirculation cyclone. (4) The fluidized bed combustion method according to claim 2, comprising the step of introducing ammonia into the combustion hot gas stream immediately upstream of the recirculation cyclone. (5) Set the combustion device to 1400-1500°F (approximately 760°F
816° C.) to produce charcoal particles and suppress nitrogen oxides with hot ash particles in the fluidized bed and recirculation path. . (6) Maintain the particle size distribution of the fluidized bed and reduce heat transfer within the fluidized bed by 1
2. The fluidized bed combustion method according to claim 1, which includes a step of increasing the fuel consumption to 00 to 200 BTU/FT2-HR-F. (7) a combustion device, a device for supplying fuel into the combustion device, and combustion of a fluidized bed containing inert particles, ash particles, and partially burned fuel particles with an average particle size in the range of 100 to 800 microns; The device that generates in the device and the 0 in the combustion device
．． A device that provides a surface flow velocity in the range of 5 to 7 feet/second (approximately 15 to 210 cm/second) and releases a significant amount of particulates from the fluidized bed, and a device that captures particles contained in the exhaust gas from the combustion device and creates a fluidized bed. equipment for returning heat to the fluidized bed at a return flow rate per hour equal to 2 to 5 times the weight of the fluidized bed, equipment for recovering heat from the fluidized bed as well as the exhaust gas stream, and equipment for collecting dust from the cooled exhaust gas stream. Fluidized bed combustion mechanism. (8) A device for supplying an absorbent for sulfur oxides into the combustion device at the same time as fuel, and inert particles, ash particles, partially burned fuel particles, and particles with an average particle size within the range of 100 to 800 microns. and a device for producing a fluidized bed containing completely reacted absorbent particles for sulfur oxides. (9) A fluidized bed combustion mechanism according to claim 7, comprising a device for introducing ammonia into the combustion hot gas stream immediately upstream of the recirculation cyclone. (10) A fluidized bed combustion mechanism according to claim 8, comprising a device for introducing ammonia into the combustion gas stream immediately upstream of the recirculation cyclone. (11) Set the combustion device to 1400-1500°F (approximately 760°F)
Fluidized bed combustion according to claim 7, comprising a device for producing charcoal particles and suppressing nitrogen oxides by hot ash particles in the fluidized bed and recirculation path. mechanism.