JPH07332612A - Apparatus for oxidizing cas and its operating method - Google Patents

Abstract

PURPOSE:To provide an apparatus for oxidizing CaS in which CaS can be effectively converted into CaSO4. CONSTITUTION:Fluidzed beds 1a, 1b and 1c are formed within an oxidizing furnace 10 constituting an apparatus for oxidizing CaS To the fluidized beds 1b and la are independently supplied fuels 101b and 101a containing CaS as well as airs 102b and 102a, respectively. Within the fluidized bed 1c is installed a heat transfer pipe 2. A dispersion plate 3b located at a part oppositely facing against a supplying nozzle 6b for supplying the fuel 101b is provided with holes closely gathered therein so as to facilitate the supplied fuel to be easily dispersed into the fluidized bed 1b. A rate of fuel supplying amount and an flow rate of air at both fluidized beds 1a and 1b is adjusted so as to adjust a local air volume and a gas vacant tower speed at both fluidized beds and concurrently a particle replacing amount between both fluidized beds 1a and 1b is controlled, a temperature of the fluidized bed la having no heat transfer pipe installed therein is set to 900 deg.C to 1100 deg.C and a temperature of the fluidized bed 1b having the heat transfer pipe installed therein is set to 850 deg.C to 950 deg.C and then the operation is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coal gasification gas containing hydrogen sulfide and the like before it is supplied to a gas turbine in a power generator for generating gasification gas using coal as a fuel and using a gas turbine and a steam turbine for power generation. Calcium sulfide produced by desulfurization of limestone (in the present invention, C
aS)), the CaS
The present invention relates to a fluidized bed combustion device that converts carbon dioxide into CaSO _{4 that} has a small impact on the environment.

[0002]

2. Description of the Related Art In a device for generating gasified gas using coal as a fuel and using a gas turbine and a steam turbine for power generation, a power generation device in which desulfurization with limestone is combined with coal gasified gas is disclosed in Japanese Patent Application No. Hei. As described in No. -50564, high efficiency power generation is possible using coal as a fuel. When desulfurizing coal gasification gas with limestone, CaS
The present invention relates to a structure of an oxidation furnace for converting CaS generated when desulfurized coal gasification gas is generated into CaSO ₄ . First, the configuration of an apparatus for producing a coal gasification gas desulfurized from coal in the power generator will be described with reference to FIG.

Coal 201 is supplied to the gasification furnace 20. In the gasification furnace 20, air 202 and the gas generated by the oxidation furnace 10 are supplied.
It is gasified by 3. The coal gasification gas 203 is supplied to the desulfurization furnace 30. The char 204 after gasification of coal is supplied to the oxidation furnace 10. Limestone 307 is supplied to the desulfurization furnace 30, limestone 307 and hydrogen sulfide in the coal gasification gas 203 are reacted, and hydrogen sulfide is fixed as CaS in limestone. Coal gasification gas 3 desulfurized in the desulfurization furnace 30
03 is sent to a gas turbine (not shown).

Oxidizer 10 mixed with air and steam
2, steam 107, char 204 produced in the gasification furnace,
And CaS-containing limestone 304 introduced from desulfurization furnace
Is supplied to the oxidation furnace 10. Char 204 in oxidation furnace 10
To burn CaS and CaSO _FourOxidize to. Char
Combusted combustion gas is gasified as oxidation furnace generated gas 103
It is supplied to the furnace 20, and the steam and nitrogen in the oxidation furnace generated gas 103
Carbon oxide serves as a gasification agent for coal in the gasifier 20
Used. The heat exchanger 2 is installed in the oxidation furnace 10,
Steam 105 is supplied and heated to steam 106,
Steam 106 is supplied to a steam turbine (not shown).
Be done.

A conventional example of the oxidation furnace will be described in more detail with reference to FIG. The oxidation furnace 10 is surrounded by a so-called water wall 2a, which has a wall surface formed by connecting pipes through which a heat medium such as water can flow, and the bottom of the oxidation furnace 10 is above the wind box 9c. The mixture 101 of char, CaS and limestone is supplied to the fluidized bed 1c from the char supply pipe 6c. The oxidizer 102, which is a mixture of air and water vapor, is supplied from the air supply pipe 7c to the wind box 9c, and is supplied into the fluidized bed 1c via the dispersion plate 3c.

In the oxidation furnace 10, the limestone containing CaS, the coal ash, and the burning char are fluidized by the oxidizer 102 that is a mixture of air and steam to form a fluidized bed 1c. The heat transfer tube 2 is installed inside the fluidized bed 1c, and the heat medium 105 of water or steam is flowed through the fluidized bed 1c.
It is heated by the heat generated in c. Char burns with oxygen in the air and is converted to carbon dioxide and ash.

CaS in limestone is oxidized to CaSO ₄
Converted to. Combustion gas 103 is supplied from pipe 4 to the upper gasification furnace. Ash and limestone are extracted from the furnace bottom nozzle 8 and discharged to the outside of the system.

[0008]

In the conventional oxidation device,
Even after the oxidation treatment, some CaS remains unreacted on the surface of the limestone. Therefore, when limestone discharged from the furnace bottom is used as a landfill material, CaS contained therein causes the following problems. That is, CaS is very slowly oxidized and converted to CaSO ₄ at room temperature, but C
A part of H ₂ S is generated from aS. Therefore, when CaS is used as a landfill material in its bare state, it increases the COD value in water and generates H ₂ S, which causes environmental pollution.

The conversion reaction from CaS to CaSO ₄ proceeds more easily at higher temperatures, and it is preferable to raise the temperature of the entire fluidized bed in the oxidation device. Since the particles in the fluidized bed are agitated very well by the bubbles, the heat exchange between the particles is good, and the temperature difference in the entire fluidized bed is small.

However, when the temperature of the fluidized bed rises, the ash in the coal is melted, and the molten ash and the ash are combined with each other, and an agglomeration phenomenon in which the ash gradually grows into a large lump of ash tends to occur. Clinker trouble occurs in which the fluidization of the whole becomes poor and the fluidized bed cannot be fluidized at last. In addition, the cost is increased because an expensive material is used to improve the durability of the heat exchanger inserted in the fluidized bed.

The present invention is a CaS capable of efficiently converting CaS to CaSO ₄ without causing clinker trouble or the like.
It is an object of the present invention to provide an oxidizing device and its operating method.

[0012]

Means and Actions for Solving the Problems The present invention is based on CaS.
The fuel containing hydrogen is reacted with oxygen in the fluidized bed to form its Ca
In order to solve the above problems in the CaS oxidation device that converts S into CaSO ₄ , the fluidized bed described above is composed of a fluidized bed partially provided with a heat transfer tube and a fluidized bed not provided with a heat transfer tube. Each layer is provided with a nozzle that independently supplies a fuel containing CaS associated with gas and a pipe that supplies air.

Further, a porous plate for injecting gas is provided on the inner wall portion of the fluidized bed, which is directly irradiated with the fuel from the nozzle for supplying the fuel containing CaS. The particles in the fluidized bed are agitated by the ascending bubbles. If the ascending speed of the bubbles is high, the agitation of the fluidized bed particles becomes difficult, the particles in the entire fluidized bed are well mixed, and the temperature of the fluidized bed is easily homogenized.

In the oxidizer according to the present invention, the amounts of fuel and air to the fluidized bed with the heat transfer tubes and to the fluidized bed without the heat transfer tubes can be adjusted independently, so that the temperature of both fluidized beds can be adjusted. Can be changed.

Further, the temperature in the fluidized bed can be made non-uniform by slowing the particle exchange rate between the particles in the fluidized bed at a high temperature and the particles in the fluidized bed at a low temperature.
If the gas superficial velocity is too slow, clinker trouble is likely to occur, and if the gas superficial velocity is high, the heat exchange rate is high and the temperature difference between the fluidized layers is less likely to occur.

The exchange rate between particles in the fluidized bed increases as the gas superficial velocity increases, and the heat exchange rate between the fluidized beds can be controlled by controlling the gas superficial velocity.

As described above, according to the oxidizing apparatus of the present invention, it is possible to control the amount of fuel such as char containing CaS that burns in the fluidized bed and the heat exchange rate due to the particle exchange between the fluidized beds. Part of the temperature is set to high and C there
It becomes possible to accelerate the oxidation of aS.

Thus, in the oxidation device according to the present invention, it is preferable that the temperature of the fluidized bed without a heat transfer tube is set to 900 °
1100 ℃, the temperature of the fluidized bed with heat transfer tube installed 850 ℃
Run at 950 ° C.

In order to operate the fluidized bed in such two different temperature portions, for example, the temperature is 900 ° to 1100.
The gas flow velocity in the fluidized bed set to ℃ is set to a gas superficial velocity of 2 to 3.5 times the minimum fluidization start speed of the fluidized particles, or a temperature of 900 ° to 1100 ° C. ,
A wall for partitioning each fluidized bed is provided between the fluidized beds whose temperature is set to 850 ° C to 950 ° C, and the amount of particle exchange is adjusted by the size of the holes opened in the wall.

On the other hand, it is in the vicinity of the dispersion plate where the movement of particles is poor and the oxygen concentration is high that the temperature of the fluid is locally highest in the fluidized bed due to the heat of combustion. When the temperature of the fluidized bed is increased, clinker is likely to be formed in the vicinity of this dispersion plate, and it is necessary to make the movement of the particles on the dispersion plate good so as not to form clinker in this part.

In the oxidizer according to the present invention, a perforated plate (dispersion plate) having a large number of small holes is installed on the opposite side of a nozzle for supplying a fuel such as limestone containing CaS, coal or char, and air is supplied from the small holes. By adopting the structure for blowing out the particles, the mixing of the particles of the dispersion plate having a large number of small holes is promoted. As a result, it becomes possible to prevent clinker growth that occurs when the jet stream of gas containing solids generated in the furnace collides face-to-face with limestone, coal or char containing CaS by air.

In this way, limestone, CaS, and coal can be satisfactorily agitated by the jets facing each other by air-transporting limestone, coal, or char containing CaS and supplying it from the nozzle into the fluidized bed. Alternatively, the effect that the char can be uniformly distributed over the entire fluidized bed is generated, and it is not necessary to install a large number of supply nozzles in order to uniformly supply limestone, CaS, coal or char to the fluidized bed as in the conventional case. The effect of reducing the number of supply nozzles of CaS, coal or char is also produced.
As described above, according to the oxidizing apparatus of the present invention, a fluidized bed portion having a high temperature and a fluidized bed portion having a low temperature are formed in the fluidized bed, and stable operation for CaS oxidation can be performed without trouble such as clinker generation.

[0023]

EXAMPLES One example of the CaS oxidation apparatus according to the present invention and the mode of operation of the apparatus will be specifically described below. First, a first embodiment shown in FIGS. 1 to 4 will be described. In FIG. 1, the oxidation furnace 10 constituting the oxidation device has a lower part made up of a wall made of a refractory heat insulating material 5 and an upper part made up of a wall made of a water wall 2a.
In the oxidation furnace 10, a fluidized bed 1a, a fluidized bed 1b and a fluidized bed 1c are provided.
To form a fluidized bed.

At the bottom of the fluidized bed is a dispersion plate 3a provided with a limestone containing CaS and a fuel supply nozzle 6a for supplying coal or char and an ash extraction pipe 8. Dispersion plate 3a
A fluidized bed 1a is formed on the upper part of the. A dispersion plate 3b and a fuel supply nozzle 6b for supplying fuel such as limestone containing CaS and coal or char to the dispersion plate 3b are attached to the upper part thereof. The fuel supply nozzles 6a and 6b are arranged so as to inject fuel toward the porous dispersion plates 3a and 3b, respectively.

A fluidized bed 1b is formed on the dispersion plate 3b. The outer walls of the fluidized bed 1a and the fluidized bed 1b are covered with a refractory heat insulating material 5 so that the heat radiation to the outside of the fluidized bed 1a and the fluidized bed 1b is suppressed to a low level. Fluidized bed 1b
Is formed with a fluidized bed 1c, and a heat exchanger (heat transfer tube) 2 is installed in the fluidized bed 1c.

The main fuel 101b such as CaS and char to the oxidation furnace 10 is supplied from the supply nozzle 6b into the fluidized bed 1b. The oxidizing agent 102b, which is a mixture of air and water vapor, is supplied to the oxidizing furnace 10 from the air supply nozzle 7b to the air box 9b, and is supplied from the dispersion plate 3b to the fluidized bed 1b via the air box 7b. The particles between the fluidized bed 1a, the fluidized bed 1b, and the fluidized bed 1c are vertically mixed by the bubbles rising therein.

Fuel such as CaS and char for setting the temperature of the fluidized bed 1a higher than that of the fluidized beds 1b and 1c
01a is supplied from the nozzle 6a to the fluidized bed 1a. The oxidizer 102a, which is a mixture of air and steam for burning the fuel, is supplied from the air supply nozzle 7a into the wind box 9a, and passes from the dispersion plate 3a to the fluidized bed 1a via the wind box 7a.
Is supplied to.

The fluidized bed 1b and the fluidized bed 1c have a fluidized bed temperature of 8
Main fuel 10 containing CaS at 50 ° to 950 ° C
1b, the amount of the oxidant 102b in which air and steam are mixed is adjusted, and the superficial gas velocity of the fluidized bed 1b is set to 3.5 to 5 times the fluidization start velocity.

If the gas superficial velocity is higher than this range, the particles in the fluidized bed are likely to flow out to the upper part, and unreacted particles are easily increased. If the gas superficial velocity is lower than this range, it becomes difficult for the supplied main fuel 101b containing CaS to be rapidly mixed into the entire fluidized bed 1b.

The heat of combustion is transferred from the heat exchanger 2 to the steam 105.
Thus, the steam 105 becomes the heated steam 106. Ca
S reacts with oxygen to CaSO_FourWill be converted to
CaO and SO₂Will also be converted. The CaO is in the fluidized bed
SO while remaining₂And O ₂Reacts with CaSO_FourWhen
Become.

On the other hand, the fluidized bed 1a has a fluidized bed temperature of 900 °
Fuels such as CaS and char 10 to be maintained at ~ 1100 ℃
1a, the amount of oxidant 102a mixed with air and water vapor is adjusted, and the gas superficial velocity of the fluidized bed 1a is adjusted to 2 to 3 times the fluidization start velocity in order to reduce the amount of particles exchanged with the fluidized bed 1b.
Set to 5 times.

If the gas superficial velocity is slower than this range, hot spots are likely to occur in the fluidized bed 1a, and so-called clinker trouble is likely to occur, in which coal ash is melted and formed into a large mass. On the other hand, if the gas superficial velocity is higher than this range, particle exchange between the fluidized beds 1b and 1a becomes too good, and it becomes difficult to set the temperature of the fluidized bed 1a higher than that of the fluidized bed 1b.

The particles of the fluidized bed 1b pass through the hot fluidized bed 1a.
Therefore, the fluidized bed 1a of the fluidized bed 1a is
Under high temperature conditions, the CaS in the ash discharged is completely
SO _FourAlternatively, it is converted to CaO. Generated in oxidation furnace 10
The generated combustion gas is passed through the pipe 4 to a gasification furnace (not shown).
Sent to.

FIG. 2 shows the dispersion plate 3a from the AA cross section of FIG.
It is the figure which looked at the dispersion plate 3b. By disposing small holes closer to B than a part of the dispersion plate 3b facing the fuel supply nozzle 6b, the main fuel 101b containing the supplied CaS is promoted to be dispersed in the fluidized bed 1b. Is considered.

FIG. 3 is a cross-sectional view of the dispersion plate 3a and the dispersion plate 3b, and FIG. 4 shows a part of the cross section CC of FIG. 3, in which the dispersion plate 3a and the dispersion plate 3b are small. It is explanatory drawing of the shape of the hole 3e. As shown in FIG. 4, the small hole 3e has a line passing through the center of the circle of the cross section and the center line of the small hole 3e whose angle D is usually 20 ° to
It is arranged to be 70 °, preferably 35 ° to 55 °.

Since the angle D causes a jet of air to move the particles on the dispersion plate 3a clockwise, the angle D
Is set to bend the jet flow containing the fuel so that the jet flow containing the fuel does not directly hit the dispersion plate 3a, and the fuel in the jet flow is uniformly dispersed in the cross section of the fluidized bed. .

Next, a second embodiment of the oxidizing apparatus according to the present invention shown in FIG. 5 will be described. In FIG. 5, the same parts as those of the first embodiment shown in FIG. 1 are designated by the same reference numerals for simplification of description.

The difference between the embodiment of FIG. 5 and the embodiment of FIG. 1 is that the fluidized bed 1a in the high temperature portion is arranged next to the fluidized bed 1c in the low temperature portion. During normal operation, ash is not extracted from the ash extraction pipe 8 ′ attached to the dispersion plate 3b installed in the fluidized bed 1b in the low temperature part, and the dispersion plate 3 installed in the fluidized bed 1a in the high temperature part is not extracted.
The ash is extracted from the ash extraction pipe 8 attached to a.

Ash removal pipe 8'attached to the dispersion plate 3b
The ash is extracted from the container only when particles having a particularly large particle size have accumulated in the fluidized bed 1b. By arranging the fluidized beds as shown in FIG. 5, the amount of particles exchanged between the fluidized beds 1a and 1c can be adjusted by adjusting the bed height of the fluidized bed 1c. Even if the speed is set to 2 to 3.5 times or more than the fluidization start speed, the fluidized bed 1a
It is possible to raise the temperature of.

The present invention has been specifically described above based on the illustrated embodiments. However, the present invention is not limited to these embodiments, and its structure and operation are within the scope of the present invention shown in the claims. It goes without saying that various changes may be added to the.

[0041]

According to the apparatus for oxidizing CaS and the method for operating the same according to the present invention, the fluidized bed for reacting CaS with oxygen is composed of a fluidized bed partially having a heat transfer tube and a fluidized bed having no heat transfer tube. However, by independently adjusting the supply of fuel containing CaS and air to both fluidized beds, the temperature of both fluidized beds can be changed and CaS can be effectively oxidized in the high temperature portion. Further, the growth of the clinker is prevented by providing the perforated plate on the inner wall of the fluidized bed facing the fuel supply nozzle containing CaS.

As described above, by adopting the oxidizer and the operating method thereof according to the present invention in the CaS oxidizer in the coal gasification power generator, almost no CaS is contained in the desulfurized limestone discharged from the coal gasification power generator. Do not contain Ca, or even if it does, CaS should not react with CaS
Since CaS is present inside the SO ₄ shell, even if it is used as a landfill material, CaS does not decompose in the environment, and it is possible to use limestone after desulfurization as a landfill material that does not adversely affect the environment.

[Brief description of drawings]

FIG. 1 is a sectional view showing the structure of an oxidizer according to a first embodiment of the present invention.

FIG. 2 is a plan view showing an example of a structure of a furnace bottom portion of a fluidized bed and a dispersion plate in the oxidation device according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view showing an example of the structure of a dispersion plate in the oxidation device according to the first embodiment of the present invention.

FIG. 4 is a sectional view showing an example of the structure of a dispersion plate in the oxidation device according to the first embodiment of the present invention.

FIG. 5 is a cross-sectional view showing the configuration of an oxidation device according to a second embodiment of the present invention.

FIG. 6 is a configuration diagram showing the concept of a coal gasification desulfurization apparatus in which an oxidizing apparatus according to the present invention is used.

FIG. 7 is a cross-sectional view showing the configuration of a conventional oxidation device.

[Explanation of symbols]

1a, 1b, 1c Fluidized bed 2 Heat transfer tube (heat exchanger) 3a, 3b, 3c Dispersion plate 3e Small hole 4 Piping 5 Fireproof heat insulating material 6a, 6b, 6c Fuel supply nozzle 7a, 7b, 7c Air supply nozzle 8, 8 'Exhaust pipe 9a, 9b, 9c Wind box 10 Oxidation furnace 101, 101a, 101b Fuel or char and C
Desulfurized limestone containing aS 102, 102a, 102b Oxidizing agent 103 Oxidizing furnace gas 104 Exhaust ash 105, 106 Steam

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location C10J 3/46 M F02C 3/28 (72) Inventor Katsuhiko Shinoda 2-5-1, Marunouchi, Chiyoda-ku, Tokyo 3 Hishi Heavy Industries Ltd.

Claims (2)

[Claims] 1. A CaS that reacts a fuel containing CaS with oxygen in a fluidized bed to convert the CaS into CaSO ₄ .
In the oxidizer, the fluidized bed is composed of a fluidized bed partially provided with a heat transfer tube and a fluidized bed not provided with a heat transfer tube, and both fluidized beds are independently accompanied by gas C
A nozzle for supplying fuel containing aS, a pipe for supplying air, and a perforated plate which is installed on an inner wall portion from which the fuel from the nozzle directly irradiates and which ejects gas are provided, and the air-fuel ratio and gas empty in both fluidized beds are provided. An apparatus for oxidizing CaS, characterized in that the tower speed is independently controllable. 2. A flow without adjusting the heat transfer tube while adjusting the local air amount and gas superficial velocity in both fluidized beds by adjusting the ratio of the fuel supply amount and the air flow rate in both fluidized beds. By controlling the gas flow velocity of the bed to control the amount of particles exchanged with the fluidized bed with the heat transfer tube installed, the temperature of the fluidized bed without the heat transfer tube set to 900 ° to 11 °
00 ℃, the temperature of the fluidized bed where the heat transfer tube is installed is 850 °
The method for operating a CaS oxidation device according to claim 1, wherein the method is operated by setting the temperature to 950 ° C.