JPH0227563B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to boilers, heating furnaces, garbage incinerators, etc.
The present invention relates to a fluidized bed combustion device used to burn solid fuel.

[Prior art] Fluidized bed combustion equipment can burn solid fuel at a relatively low temperature in solid particles, so the content of nitrogen oxides contained in exhaust gas is small and deflow is possible within the fluidized bed. Because it has excellent advantages such as being able to use bottom-grade coal as fuel, it is widely used in boilers, heating furnaces, garbage incinerators, etc.

[Problems to be solved by the invention] The thickness of the fluidized bed in a conventional fluidized bed combustion apparatus generally requires 1 to 2 m, which increases the operating power cost and increases the speed of particles due to the growth of air bubbles. Because of this, there were drawbacks such as the high cost of countermeasures for heat exchanger tube wear. Furthermore, in order to comply with the current strict pollution regulations, it is necessary to further effectively reduce nitrogen oxides (NOx) and sulfur oxides (SOx), and the utilization rate of desulfurization is at its lowest (for example, Ca /S molar ratio = 4, the desulfurization agent was about 9%).

The present invention aims to solve the conventional drawbacks and problems by significantly reducing nitrogen oxides, improving desulfurization performance, and reducing the thickness of the fluidized bed to reduce operating power costs and heat exchanger tube wear. It is.

[Means for Solving the Problems] The present invention provides a fluidized bed furnace, a spouted bed furnace that is integrated with the fluidized bed furnace and extends vertically, and supplies air from below the fluidized bed furnace. A primary air supply port, a jet air supply port that blows out air from below the fluidized bed position of the fluidized bed furnace in the spouted bed furnace, and an upper part of the fluidized bed furnace above the fluidized bed position are communicated with the spouted bed furnace. an upper communication port, a lower communication port that communicates the lower part of the fluidized bed of the fluidized bed furnace with the spouted bed furnace, and particles that are provided in the upper part of the fluidized bed furnace and supply fuel and desulfurization agent into the fluidized bed furnace. A supply port, a dust collector connected to an upper outlet of the spouted bed furnace and returning scattered particles to the particle supply port, and an ash extraction port provided below the spouted bed furnace. This is related to a fluidized bed combustion equipment.

[Function] The fluidized bed of the fluidized bed furnace is thinned, the sulfur dioxide gas that remains without being desulfurized in the fluidized bed furnace is degassed in the spouted bed furnace, and the ash scattered from the spouted bed furnace is circulated to the fluidized bed furnace. The ash remaining in the spouted bed furnace will be extracted from the ash outlet.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

In FIGS. 1 and 2, a cylindrical spouted bed furnace 2 with a small diameter and long vertically is disposed at the center of a large-diameter cylindrical fluidized bed furnace 1. A diffuser plate 3 is attached nearby, and a wind box 4 is formed below the diffuser plate 3. A primary air supply port 5 is provided at the bottom of the fluidized bed furnace 1.
Air is supplied into the wind box 4 via the valve 6, the air supply pipe 7, and the primary air supply port 5. The air supplied into the air box 4 is supplied above the air diffuser plate 3 through a large number of holes formed in the air diffuser plate 3. A particle supply port 8 is provided on the top surface of the fluidized bed furnace 1, and solid fuel such as coal is supplied from a fuel feeder 9 provided outside the fluidized bed furnace 1, and a desulfurization agent feeder 10 is supplied thereto. A desulfurizing agent is supplied to the fluidized bed furnace 1 through a particle supply port 8.

A plurality of lower communication ports 11 located on the upper surface of the diffuser plate 3 and a plurality of upper communication ports 12 located on the lower portion of the upper surface of the fluidized bed furnace 1 are bored in the outer peripheral wall of the spouted bed furnace 2. , the lower and upper parts of the fluidized bed furnace 1 are communicated with the inside of the spouted bed furnace 2. A pipe-shaped jet air supply port 13 is attached to the lower part of the spouted bed furnace 2, and the secondary air is forced upward into the spouted bed furnace 2 through the valve 14 and the jet air supply port 13. It is becoming well supplied. The lower end of the spouted bed furnace 2 is connected to an ash outlet 15.

A tertiary air supply port 16 is provided in a portion of the spouted bed furnace 2 that projects above the fluidized bed furnace 1, and tertiary air is supplied via a valve 17 as necessary. There is. The upper outlet of the spouted bed furnace 2 is connected to a dust collector 18 such as a cyclone, which separates particles from gas and sends the particles to a particle supply port 8.
The gas is supplied to the inside of the fluidized bed furnace 1, and the gas is discharged to the outside through a chimney or the like.

In the fluidized bed combustion apparatus shown in FIGS. 1 and 2 described above, the particle supply port 8 of the fluidized bed furnace 1 is
The fuel and desulfurizing agent supplied into the chamber are filled relatively thinly on the diffuser plate 3 as fluidization 19. The fluidized bed 19 is fluidized and formed by the air supplied from the primary air supply port 5 through the wind box 4, and the fuel is burned under air-deficient conditions to suppress the production of nitrogen oxides. Fly ash containing unburned carbon and small cinders enters the spouted bed furnace 2 through the upper communication port 12, mixes with the high-speed secondary air supplied from the spouted air supply port 13, and flows into the spouted bed furnace 2. secondary combustion occurs. In addition, sulfur dioxide gas remaining without being desulfurized in the fluidized bed 19
SO ₂ is desulfurized in an entrained bed furnace 2 in an atmosphere of excess air. Scattered particles such as ash from the spouted bed furnace 2 are separated by a dust collector 18 disposed at the outlet of the spouted bed furnace 2, and circulated into the fluidized bed furnace 1 through the particle supply port 8.

The coarse ash remaining in the fluidized bed 19 is moved into the spouted bed furnace 2 through the lower communication port 11 and selectively separated by secondary air supplied from the spouted air supply port 13. The ash is extracted from the ash extraction port 15. The opening degrees of the valves 6 and 14 are adjusted to change the balance between primary air and secondary air, and the valve 17 is opened as necessary to supply tertiary air to a portion above the upper communication port 12.

3 and 4 show other embodiments of the present invention, and the same parts as in FIGS. 1 and 2 are given the same reference numerals.

In the embodiment shown in FIGS. 3 and 4, a spouted bed furnace 2 also having a rectangular cross section is provided on one side of a fluidized bed furnace 1 having a rectangular cross section, and an evaporation tube 21 is provided in the fluidized bed 19. It is used as a fluidized bed boiler, and the combustion conditions are shown in Figures 1 and 2.
There is no difference from the embodiment shown in the figure.

The fluidized bed furnace 1 and the spouted bed furnace 2 may be circular or rectangular, or may have a combination of other shapes. The optimum position for the circulation return is selected depending on the fuel. Further, the installation location of the evaporation tube 21 is not limited to the inside of the fluidized bed 19, but may be installed on the side wall of the fluidized bed furnace 1 or in the exhaust gas passage path above the spouted bed furnace 2.

[Effect of the invention] The present invention has the following effects.

(i) Since there is a lack of air in a fluidized bed furnace and an excess of air in an entrained bed furnace, nitrogen oxides can be significantly reduced and high desulfurization performance can be achieved.

(ii) Since the secondary side in the spouted bed furnace has good combustibility, the fluidized bed on the primary side in the fluidized bed furnace can be made thinner, and the operating power can be reduced.

(iii) Since the fluidized bed is thin, bubbles do not grow and there is less wear on evaporation tubes, etc.

(iv) By returning the scattered particles to the fluidized bed furnace on the primary side, combustibility and desulfurization properties can be further improved, and the amount of desulfurization agent consumed can be reduced.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of one embodiment of the present invention, FIG. 2 is a cross-sectional view of FIG. FIG. In the figure, 1 is a fluidized bed furnace, 2 is an entrained bed furnace, 5 is a primary air supply port, 8 is a particle supply port, 11 is a lower communication port, 12 is a lower communication port, 13 is a jet air supply port,
Reference numeral 15 indicates an ash extraction outlet, and reference numeral 18 indicates a dust collector.

Claims (1)

[Claims] 1. A fluidized bed furnace, an entrained bed furnace that is integrally formed with the fluidized bed furnace and extends vertically, and a primary air supply port that supplies air from below the fluidized bed furnace.
a jet air supply port that blows out air from below the fluidized bed position of the fluidized bed furnace in the spouted bed furnace;
an upper communication port that communicates between an upper part of the fluidized bed of the fluidized bed furnace and the spouted bed furnace; a lower communication port that communicates the lower part of the fluidized bed of the fluidized bed furnace with the spouted bed furnace;
a particle supply port provided in the upper part of the fluidized bed furnace to supply fuel and desulfurization agent into the fluidized bed furnace; and a dust collector connected to an upper outlet of the spouted bed furnace to return scattered particles to the particle supply port. , and an ash extraction port provided below the spouted bed furnace.