JPH0335930Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a fluidized bed boiler for fluidized combustion of coal, etc., and particularly relates to a fluidized bed boiler provided with a desulfurizing material fluidized bed.

[Prior Art] As is well known, in a fluidized bed boiler, a gas dispersion plate is installed inside a furnace body, a fluidized combustion section is formed above the gas dispersion plate, and a fluidized combustion section is formed below the gas dispersion plate. forms an air chamber. Then, particles such as coal flow together with the fluidizing medium and are combusted by the air blown up from the air chamber through the gas distribution plate.

As this type of fluidized bed boiler, a fluidized bed of desulfurization material such as limestone is formed downstream of a combustion section that uses sand as a fluidized medium to burn solid particles such as coal,
In recent years, a system has been developed in which the gas from the combustion fluidized bed is introduced into the desulfurization material fluidized bed for desulfurization.

[Problem that the invention aims to solve] Unburned particles (carbon) scattered from the fluidized combustion section
is introduced directly into the desulfurization material fluidized bed, resulting in low combustion efficiency.

In addition, when desulfurization is performed by introducing combustion gas into a fluidized bed of desulfurization material, if the amount of particles (ash) contained in the combustion gas increases, such as when the solid fuel has a high ash content, the desulfurization reaction will be hindered. Desulfurization efficiency may decrease. That is, CaSO ₄ , which is a desulfurization reaction product, has the effect of lowering the melting point of the atsushi, so if too much atsushi flows into the fluidized deflow bed, the atsushi will melt and stick to the surface of the desulfurization agent particles such as limestone. The deflow reaction becomes obstructed.

[Means for Solving the Problems] The fluidized bed boiler of the present invention comprises: a combustion section that performs fluidized combustion of fuel; a desulfurization section that forms a desulfurization material fluidized bed provided downstream of the fluidized combustion section; The present invention includes a collection section provided between the combustion section and the desulfurization section for collecting scattered particles from the combustion section, and a path for returning the collected matter in the collection section to the combustion section.

[Operation] In the fluidized bed boiler of the present invention, fuel such as coal is supplied to the combustion section and is fluidized and combusted. A suitable fluidizing medium, for example sand, is fed into this combustion section. A considerable amount of unburned carbon scattered from the combustion section and small diameter particles in the ash is collected in the collection section and sent to the combustion section again. In this way, the unburned fuel introduced from the collection section is introduced into the combustion section at a high temperature, so the temperature of the combustion section does not drop and both the fuel and the returned unburned components are efficiently combusted. be done.

In addition, since the combustion gas from which the required amount of particles have been collected and separated in the collection section is introduced into the desulfurization section, inhibition of the desulfurization reaction by particles (ash) is prevented.
An efficient desulfurization reaction is carried out.

[Example] Examples will be described below with reference to the drawings.

FIG. 1 is a system diagram showing a fluidized bed boiler according to an embodiment of the present invention. Reference numeral 10 is the main body of the fluidized bed boiler, in which a dispersion plate 14 is installed at the bottom of the furnace body 12, the lower side of the dispersion plate 14 is used as an air chamber 16, and the upper side of the dispersion plate 14 is used for fluidized combustion. A combustion section 18 is formed. Reference numeral 20 indicates a pipe for supplying fuel (coal in this embodiment).

A water pipe 22 is installed in the furnace body 12, and an opening 26 is provided on the side in the upper freeboard section 24, which communicates with a chamber 30 of an inertial dust collector 28 as a collection section. This inertial dust collector 28 is equipped with a collision plate 32, and the combustion gas from the freeboard portion 24 goes around the bottom of the collision plate 32 and flows downstream, and the inertial dust collection of scattered particles is carried out within this chamber 30. It is done.

The inertial dust collector 28 is connected to the desulfurization section 34. This desulfurization section 34 fluidizes limestone as a desulfurization material supplied from a supply pipe 36 on a dispersion plate 38 to form a fluidized bed of limestone to perform desulfurization. A first waste heat boiler 40 and a second waste heat boiler 42 are installed in series on the downstream side of the desulfurization section 34. Reference numeral 44 indicates these waste heat boilers 4.
0 and 42, and 46 indicates a duct for guiding the gas passing through the waste heat boiler 42 to a bag filter, an electrostatic precipitator, etc. Reference numeral 48 denotes a dust collector, which is connected to the ash processing device via a powder discharge device such as a rotary valve 50 and piping 52.

A system 58 consisting of a pipe 54, a rotary valve 56, etc. is connected to the lower end of the chamber 30 so as to return the collected material to the combustion section 18. Note that the reference numeral 54a is a discharge pipe for appropriately extracting the debris in the collected material from the middle of the pipe 54.

Reference numeral 60 indicates a discharge pipe for withdrawing the fluid medium and large-diameter ash and sending it to the separator 62. Reference numeral 64 indicates a discharge pipe for large particles from the separator 62, and 66 indicates a recycle line for small particles.

In the fluidized bed boiler configured in this way,
Coal as a fuel is supplied to the combustion section 1 through a supply pipe 20.
8 and is fluidized and combusted by the air blown up from the air chamber 16. The combustion gas rises within the furnace body 12, exchanges heat with the water tube 22, and is then introduced into the inertial dust collector 28 through the opening 26, where a required amount of scattered particles are collected. The gas is further introduced into the desulfurization section 34,
The limestone desulfurization material supplied from the supply pipe 36 undergoes a desulfurization reaction while passing through the fluidized bed, and then sequentially passes through the first waste heat boiler 40 and the second waste heat boiler 42 to exchange heat, and then the duct 46 is extracted from the fluidized bed boiler.

Particles collected by the inertial dust collector 28 are transferred to the pipe 54
Then, it is introduced into the combustion section 18 again at a high temperature, and the unburned components contained in the combustion ash and collected particles are re-burned. Further, the fluidized medium and combustion ash extracted from the combustion section 18 through the discharge pipe 60 are separated into large diameter ones and small diameter ones in the combustion ash and fluidized media in the separator 62. The material passes through the discharge pipe 64,
Discarded after heat recovery. In addition, small-diameter particles are returned to the combustion section 18 of the furnace body 12 through the recycling line 66 and reused as a fluidized medium. Incidentally, an ash portion of the collected matter collected by the inertial dust collector 28 is appropriately extracted from the discharge pipe 54a.

Since the particles collected by the inertial dust collector 28 are directly introduced into the combustion section 18 without being cooled, the temperature of the combustion section 18 does not decrease, resulting in efficient combustion (fuel combustion). and combustion of the returned unburned matter).

Further, since the gas in which the required amount of scattered particles have been collected and separated by the inertial dust collector 28 is introduced into the desulfurization section 34, a decrease in desulfurization efficiency due to ash is prevented, and an extremely efficient desulfurization reaction is carried out. .

In this embodiment, if sand is used instead of limestone as the fluid medium in the combustion section 18, the combustion section 1
Since CaSO ₄ , a product of desulfurization reaction by limestone, is not included in the particles scattered from 8, when the particles are re-burned, CaSO ₄ decomposes and sulfur oxides are generated again, making it difficult to use limestone for desulfurization. Combustion section 18
There is no need to supply even more. And in this case, the product of the desulfurization reaction CaSO ₄
If coal ash is mixed with coal ash, the melting point of the coal ash will drop and it will tend to stick to the dust collector 28, but this does not happen.

Note that by adjusting the protruding length of the collision plate 32 into the chamber 30, the particle collection efficiency within the inertial dust collector 28 can be adjusted, thereby reducing the amount of scattered particles (ash) sent to the desulfurization section 34. ) can be controlled. Also,
As shown by the dashed line in Figure 1, the chamber 30
The amount of thrust may be controlled by providing another collision plate 70 on the upper part of the inner wall, or in place of the collision plate 32, by providing a buffle in which a large number of plates are provided diagonally at intervals in the vertical direction.

In the above embodiment, a plurality of furnace bodies 12 are installed together, and the combustion waste gas from each furnace body 12 is introduced into a common desulfurization section 34, but one desulfurization section is provided for one furnace body. may be provided.

Further, although two waste heat boilers are installed in series, this installation method is arbitrary. The separator 62 may be provided in the middle of the piping 60.

[Effect] As described above, in the fluidized bed boiler of the present invention, unburned matter and debris contained in the combustion gas from the combustion section that performs fluidized combustion of fuel are collected and returned to the combustion section. , a temperature drop in the combustion section due to the input of the collected material is prevented, resulting in good combustion efficiency. In addition, the amount of unburned matter generated from the fluidized bed boiler as a whole is also small. Furthermore, desulfurization efficiency can be improved by reducing scattered particles in the combustion gas introduced into the desulfurization section.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing an embodiment of the present invention. 18... Combustion section, 28... Inertial dust collector, 34
... Desulfurization section, 40, 42 ... Waste heat boiler.

Claims (1)

[Scope of claim for utility model registration] A combustion section that performs fluidized combustion of fuel, a desulfurization section that forms a fluidized bed of desulfurization material provided downstream of the fluidized combustion section, and between the combustion section and the desulfurization section. A fluidized bed boiler comprising: a collection section for collecting scattered particles from the combustion section; and a path for returning the collected material from the collection section to the combustion section.