JP2000227205A - Simultaneous denitration desulfurization system and coal gasification combined power generation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the rate of desulfurization and decompose NH3 to decrease the load of a denitration system or to eliminate the necessity of the denitration system itself, by charging a Ni catalyst having NiO as a main component and limestone into a desulfurization furnace. SOLUTION: A Ni catalyst having NiO as a main active component is supplied to a desulfurization furnace 2 through a catalyst charging pipe 25 from a charging hopper 24 by using a particle supplying device. It is possible for the Ni catalyst to be supplied to a limestone supplying pipe 14 and to be supplied to a desulfurization furnace 2 with limestone. The Ni catalyst to be supplied is a fresh Ni catalyst at the beginning of operation, but afterwards, it is the mixture of the recycled portion of the used Ni catalyst and the fresh Ni catalyst as makeup. In the desulfurization furnace 2, the concentration of H2S in coal gasification gas is desulfurized to 10 ppm or less, for example, by the action of the limestone and NiO in the Ni catalyst, and at the same time NH3 is decomposed to nitrogen and hydrogen by the catalytic action.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a simultaneous denitration and desulfurization system and an integrated coal gasification combined cycle system, and more particularly, to purifying a coal gasification gas discharged from a coal gasification furnace by simultaneously removing a denitration gas from the gasification gas. The present invention relates to a desulfurization simultaneous denitration desulfurization system and an integrated coal gasification combined cycle system.

[0002]

2. Description of the Related Art Conventionally, an integrated coal gasification combined cycle system has been developed to improve the power generation efficiency of a coal-fired power plant. FIG. 2 shows an example of the system. FIG.
Then, coal gasifier 1, desulfurization furnace 2, oxidation furnace 3, dust removal device 6, gas turbine 8, steam turbine 13, denitration device 11
The system is configured from the above.

When gasifying carbon and hydrogen in coal as carbon monoxide, carbon dioxide, hydrogen or steam,
The sulfur content in coal is mainly hydrogen sulfide (H ₂ S)
And a small amount of carbonyl sulfide (COS) mainly containing ammonia (NH ₃ ) or a small amount of hydrogen cyanide (H
CN) and the like are mixed into the gasified gas. The incorporation of H ₂ S and the like promotes corrosion of the metal pipes, and becomes a source of sulfur oxides (SOx) when the gasified gas is burned in the gas turbine combustor 7. In addition, mixing of nitrogen such as NH ₃ is a source of nitrogen oxides (NOx). Therefore, it is necessary to remove or detoxify H ₂ S, COS, NH _{3 and the} like in the coal gasification gas.

In the conventional system example shown in FIG. 2, a desulfurization furnace is installed downstream of the coal gasifier 1 to perform limestone desulfurization to remove sulfur. For the nitrogen content, a denitration device is installed at the gas turbine outlet, and NOx generated is selectively reduced with a catalyst to make it harmless. Desulfurization by limestone, by the following reaction Scheme I and II Scheme I CaC0 ₃ → CaO + C0 ₂ Scheme _{II CaO + H 2 S → CaS} + H 2 O, Ca0 + COS → CaS + CO 2, coal gas H ₂ S, CO generated during the reduction
S can be desulfurized to about 100 ppm. The desulfurized CaS is discharged from the desulfurization furnace 2 and supplied to the oxidation furnace 3.

The oxidizing furnace 3 is supplied with desulfurized material desulfurized from the desulfurizing furnace 2 and exhaust ash containing unburned components from the gasification furnace 1. %. In the oxidizing furnace 3, CaS in the desulfurizing material is oxidized as in the following reaction formulas III and IV together with complete combustion of the unburned portion. Scheme III CaS + 20 ₂ → CaSO ₄ Scheme _{IV CaS + 3/20 2 → CaO +} S0 S0 2 released by ₂ above Scheme IV are immobilized again as gypsum (CAS0 ₄₎ by the following reaction . Scheme _{V CaO + S0 2 + 1/20 2} → CaS0 4 or more stabilized desulfurizing material as CAS0 _4, ash from coal, is discharged out of the system based.

[0006] The features of such prior art are (1)
Because it can be desulfurized at around 950 ° C with limestone, there is no need to cool the temperature of coal gasification gas, and it is highly efficient as a power generation system. Can be However, in the conventional system described above, since (3) limestone desulfurization, the H ₂ S + COS concentration at the desulfurization furnace outlet is limited to about 100 ppm at about 950 ° C. at which the desulfurization furnace is operated, and SOx downstream of the gas turbine is The concentration is limited to about 50 ppm. For future use as a power plant near an urban area in Japan, a lower concentration of SOx may be required, and in that case, a separate desulfurization device is required. Also,
(4) NH ₃ generated in the gasification furnace is supplied to the gas turbine combustor with almost no decomposition in the desulfurization furnace filled with limestone, and is converted into NOx. In order to remove this NOx, a separate denitration device is required, and there is a problem that the cost is increased. Therefore, in the integrated coal gasification combined cycle system, it is necessary to solve the problems (3) and (4) while utilizing the features of the conventional systems (1) and (2).

[0007]

SUMMARY OF THE INVENTION In view of the above problems, the present inventors have improved the desulfurization rate in a desulfurization furnace, decomposed NH ₃ , and reduced the load on the denitration device without adding a complicated device. In addition, the intense study was conducted to develop a system that eliminates the need for a denitration device itself. As a result, the present inventors have found that in the integrated coal gasification combined cycle system, limestone and N
A simultaneous denitration and desulfurization system for charging a catalyst containing iO and as a main component, or Ni downstream of the desulfurization furnace,
It has been found that such a problem can be solved by providing a simultaneous denitration and desulfurization system in which a reactor composed of a Ni-based catalyst containing O as a main component is installed. The present invention has been completed from such a viewpoint.

[0008]

That is, the present invention relates to a system having a gasification furnace, a desulfurization furnace and an oxidation furnace, wherein a Ni-based catalyst mainly composed of NiO and limestone are charged into the desulfurization furnace. It is intended to provide a simultaneous denitration and desulfurization system characterized by the following, and an integrated coal gasification combined cycle system provided with the simultaneous denitration and desulfurization system. Here, the catalyst charged in the desulfurization furnace is oxidized and regenerated in the oxidation furnace,
It is preferable to provide a denitration / desulfurization system in which a catalyst separation / recovery device is provided in the ash treatment system from the oxidation furnace, and only the Ni-based catalyst particles are separated and recovered by the catalyst separation / recovery device and re-input to the desulfurization furnace. Further, it is preferable to use a fluidized bed at normal pressure as the above-mentioned catalyst separation and recovery device, and to extract only Ni-based catalyst particles having a large specific gravity from the furnace bottom by a gentle fluidized bed near the fluidization start speed. And, as the Ni-based catalyst,
For example, it is a supported catalyst containing NiO as a main component, and the carrier of the supported catalyst is at least one oxide (composite oxide) selected from the group consisting of SiO ₂ , Al ₂ O _3, and MgO, or a main component thereof. And those made of natural minerals. Cr, Fe, Cu, Z
It may contain one or more compounds selected from the group consisting of n, Ce, Pr, Ru, Rh, Pd and Pt.

According to the present invention, in a system having a gasification furnace, a desulfurization furnace, and an oxidation furnace, a fixed-bed reactor using a Ni-based catalyst containing NiO as a main component is installed downstream of the desulfurization furnace. An object of the present invention is to provide a simultaneous denitration and desulfurization system and a combined coal gasification combined cycle system provided with the simultaneous denitration and desulfurization system. In the denitrification desulfurization system and the integrated coal gasification combined cycle system, the Ni-based catalyst
This is a supported catalyst containing NiO as a main component, and its shape can be used without any particular limitation. For example, a granular catalyst or a honeycomb catalyst can also be used. Here, in order to minimize the amount of Ni-based catalyst material that is more expensive than limestone, two or more fixed bed reactors are connected in parallel, and coal gasification gas and regeneration gas are separately supplied to each reactor. When the denitrification and desulfurization performance of the reactor that supplied and supplied coal gasification gas decreased, the gas supplied to each reactor was switched, and denitration was continuously performed while repeating denitration and desulfurization and regeneration in each reactor in sequence. Desulfurization can also be performed. For example, two fixed-bed reactors are connected in parallel, coal gasification gas is supplied to one reactor, regeneration gas is supplied to the other reactor, and supply is performed at the stage where the denitrification and desulfurization performance of one reactor decreases. The gas is switched, the coal gasification gas is supplied to the other reactor, the regeneration gas is supplied to the one reactor, and the simultaneous denitration and desulfurization is continuously performed while sequentially repeating the denitration and desulfurization and regeneration using the two reactors. An embodiment is mentioned.

Further, the present invention relates to a system having a gasification furnace, a desulfurization furnace and an oxidation furnace, wherein a moving bed reactor and a moving bed using a Ni-based catalyst containing NiO as a main component are provided downstream of the desulfurization furnace. An object of the present invention is to provide a simultaneous denitration and desulfurization system provided with a regenerating apparatus, and a combined coal gasification combined cycle system including the simultaneous denitration and desulfurization system. In this denitration and desulfurization system and the integrated coal gasification combined cycle system, the Ni-based catalyst is a supported catalyst containing NiO as a main component, and its shape can be used without any particular limitation. Used for

According to the present invention, it is possible to improve the desulfurization rate in a desulfurization furnace, decompose NH ₃ , reduce the load on the denitration device, or eliminate the need for the denitration device itself without adding a complicated device. That is, according to the system of the present invention,
By injecting a Ni-based catalyst containing NiO as a main component into a desulfurization furnace at the same time as limestone, it is possible to achieve an H ₂ S concentration that cannot be achieved by conventional desulfurization of limestone alone, and to reduce the SOx concentration at the gas turbine outlet. it can.

Further, according to the present invention, it is not necessary to provide a separate denitration apparatus for removing NOx converted from NH ₃ generated in the gasification furnace by decomposition of NH ₃ by the Ni-based catalyst, and the denitration can be performed at low cost. It can be performed. Further, in the present invention, since limestone can be used for desulfurization at around 950 ° C., there is no need to cool the temperature of coal gasification gas, and when used as a power generation system, the efficiency is high, and inexpensive limestone and a recycled Ni-based catalyst are used. And low cost. Hereinafter, the present invention will be described in detail.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1, 6 and 7 show schematic diagrams of a system according to a preferred embodiment of the present invention.
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Embodiment (No. 1) FIG. 1 shows a schematic configuration diagram of an integrated coal gasification combined cycle system according to the present embodiment (No. 1). The main difference between this combined power generation system and the conventional combined power generation system is that a simultaneous denitration / desulfurization including a catalyst introduction pipe 25 for charging / collecting a Ni-based catalyst, a hopper 24 attached thereto, and a catalyst separation / recovery device 23. The point is that a system is provided.

A Ni-based catalyst containing nickel oxide (NiO) as a main active component (hereinafter abbreviated as Ni-based catalyst) is supplied from a charging hopper 24 to a desulfurization furnace 2 from a catalyst charging tube 25 using a particle supply device. . Limestone supply pipe 1 with Ni-based catalyst
4 and together with limestone to the desulfurization furnace 2. The supplied Ni-based catalyst is a fresh Ni-based catalyst at the beginning of the operation, and thereafter, a mixture of the used Ni-based catalyst regenerated and the fresh Ni-based catalyst as makeup. In the desulfurization furnace 2, the H ₂ S concentration in the coal gasification gas is desulfurized to 10 ppm or less by the action of limestone and NiO in the Ni-based catalyst,
At the same time, NH ₃ is converted to nitrogen (N ₂ ) and hydrogen (H ₂ ) by catalytic action.
And is decomposed into

The Ni-based catalyst is supplied to the oxidation furnace 3 together with the used limestone. In the Ni-based catalyst at this stage, nickel as an active component is converted into nickel sulfide (NiS) by a desulfurization action. In the oxidation furnace 3, the NiS is oxidized to NiO, and the desulfurization ability is regenerated. Since the Ni-based catalyst regenerated in the oxidizing furnace 3 is in a state of being mixed with gypsum and ash derived from coal, the Ni-based catalyst separation / recovery device 23 is provided in the discharged ash treatment system in a fluidized bed at normal pressure to perform the fluidization. The Ni-based catalyst particles having a large specific gravity are segregated in the lower part of the fluidized bed in the bed, the Ni-based catalyst particles are recovered from the furnace bottom, and the other particles are extracted from the upper part of the furnace. The recovered Ni-based catalyst particles are returned to the charging hopper 24 via the catalyst re-supply pipe 27, and are again supplied to the desulfurization furnace 2 for reuse.

In the desulfurization furnace 2, denitration and denitration are performed by the action of a Ni-based catalyst.
The desulfurized coal gas is burned in the gas turbine combustor 7, and if necessary, NOx is selectively reduced to N ₂ by the denitration device 11 downstream of the gas turbine, and then discharged from the chimney 12. In the system of the present embodiment, since the amount of NH ₃ is reduced by the action of the Ni-based catalyst,
1 is no longer required, or the load is reduced to 15% or less compared to conventional systems.

Regarding the system in the present embodiment,
The operation and effect of the configuration shown in FIG. 1 will be specifically described.
In the conventional system described with reference to FIG.
Limestone fed to the reaction formula I CaC0 ₃ → CaO + C0 ₂ Scheme _{II CaO + H 2 S → CaS} + H 2 O, produced during coal gasification by reaction of CaO + COS → CaO + CO ₂ H ₂ S, COS
Can be desulfurized to about 100 ppm. However, as shown in FIG. 3, from the thermodynamic equilibrium calculation, at the operating temperature of the desulfurization furnace and the partial pressure of steam, H ₂ S = 60 pp
m is the limit that can be desulfurized.

On the other hand, in the system of the present invention described with reference to FIG. 1, the reaction VI NiO + H ₂ S → NiS + desulfurization reaction of H ₂ 0 to proceed. As shown in FIG. 3, the equilibrium H ₂ of NiO at the temperature at which the desulfurization furnace is
The S concentration is 0.003 ppm, and the H ₂ S concentration at the desulfurization furnace outlet, which cannot be reached by the conventional desulfurization of limestone alone, is 10 ppm.
The following can be achieved: Assuming that H ₂ S + COS = 10p
In the case of desulfurization to pm, the present system allows the SOx concentration at the gas turbine outlet to be about 2 ppm.
Further, in the present system, it is also possible to use a Ni-based catalyst and limestone in combination to perform, for example, crude desulfurization to about 100 ppm with limestone and to perform precise desulfurization from 100 ppm to about 10 ppm with a Ni-based catalyst. According to such a method, there is an advantage that the usage amount of the Ni-based catalyst can be reduced as compared with desulfurization using only the Ni-based catalyst.

On the other hand, the NH originally contained in the Ni-based catalyst_ThreeDisassembly
NH generated during coal gasification due to activity_ThreeIs the following
Decomposed by reaction. Reaction VII 2NH_Three→ N_Two+ 3H_Two FIG. 4 shows NH of the Ni-based catalyst._ThreeTo investigate resolution
The results of the tests performed are shown. From this figure, the operating temperature 950
Around ℃_ThreeIt can be seen that the decomposition rate is 85% or more
You. NH_ThreeNH by decomposition_ThreeConcentration drop is caused by gas turbine
To reduce the NOx concentration at the outlet,
Can be reduced to 15% or less of the related art. Sand
That is, for example, a
Monmonia (NH _Three) Can be reduced. Also, denitration
Reduce equipment size by reducing equipment processing gas volume
For this purpose, denitrify only part of the processing gas volume and do not
The method of mixing with the amount of exhaust gas and adjusting to the outlet NOx target value
Conceivable.

Since the active component in the Ni-based catalyst which has become NiS by the desulfurization action cannot absorb sulfur S any more, it is discharged from the desulfurization furnace together with the desulfurized CaS and supplied to the oxidation furnace. Same as the conventional oxidation furnace described above 90
Temperature range of from 0 to 950 ° C., when operating in oxygen concentration of 4% of, NiS decomposes in NiS0 ₄ is 840 ° C. or higher S
In order to release O ₂ , only the following oxidation reaction proceeds. The reaction _{VIII NiS + 3/20 2 → NiO +} S0 2 emitted S0 ₂ is absorbed by CaO, CAS0
₄ Immobilized as (gypsum). That is, in a desulfurization furnace,
The Ni-based catalyst which has become iS and has lost the desulfurization ability is regenerated into NiO in the oxidation furnace, and the desulfurization ability is restored again.

The Ni-based catalyst regenerated in the oxidation furnace includes gypsum,
It is in a state of being mixed with ash derived from coal, and it is necessary to separate and collect it because only the Ni-based catalyst is supplied to the desulfurization furnace again. Therefore, in the present embodiment, a catalyst separation and recovery apparatus 23 having a fluidized bed at normal pressure as shown in FIG. In the fluidized bed of this apparatus, Ni-based catalyst particles having a large specific gravity are segregated at the lower portion of the fluidized port, the Ni-based catalyst particles are recovered from the furnace bottom, and other particles are extracted from the upper part of the furnace. The ash discharged from the oxidation furnace 3 is supplied to a catalyst separation and recovery device 23 through a discharge pipe 22. The feed particles are fluidized by fluidizing air 29,
Ni-based catalyst particles 31 having a large specific gravity are segregated to the furnace bottom, and other ash having a small specific gravity is segregated to the upper part of the furnace. Ni based catalyst particles are withdrawn from the Ni-based catalyst withdrawal tube (catalyst resupply pipe) 27, other CaO, CaC0 _3, CaS0 mixtures such as ₄ Coal-derived ash is discharged from the ash discharge pipe 28.

Embodiment (No. 2) FIG. 6 is a schematic diagram showing an example of an integrated coal gasification combined cycle system according to the present embodiment. Unlike traditional systems,
Behind the cyclone 4 downstream of the limestone desulfurization furnace 2, Ni
A simultaneous denitration and desulfurization system having a fixed bed reactor 101 filled with a system catalyst is installed. In this reactor 101, the NH ₃ in the gas is decomposed and the gas is subjected to depth desulfurization to about 10 ppm. Further, in order to restore the desulfurization performance, the configuration is such that a regeneration gas can be flowed. Hereinafter, these configurations will be described.

The gasification gas generated in the coal gasifier 1 is
Desulfurized with limestone in desulfurization furnace 2
H in the_TwoDesulfurized to about S + COS = 100ppm
You. The gas desulfurized in desulfurization furnace 2 is
After the dust in the catalyst is roughly removed, the Ni-based catalyst fixed bed reaction
Is supplied to the vessel 101. Ni-based catalyst in reactor 101
Is catalyzed by NH in the coal gasification gas. _ThreeA minute
And the active ingredient nickel oxide (NiO)
By reacting with nickel sulfide (NiS) by desulfurization,
H_TwoDesulfurize to about S + COS = 10 ppm. That
Therefore, the desulfurization capacity of desulfurization with a Ni-based catalyst is
It is defined by the amount of Kel. However, nickel sulfide is oxidized
To regenerate into nickel oxide and have desulfurization activity again
Can be used repeatedly.

Therefore, in order to reduce the amount of the Ni-based catalyst material that is more expensive than limestone, for example, as shown in FIG.
Providing two reactors and, while processing coal gasification gas (reducing gas) in the first reactor, oxidizing gas (for example, air) is passed through the Ni-based catalyst in the second reactor to regenerate Can be. After the regeneration in the second reactor is completed, the gas is switched to process the coal gasification gas in the second reactor, and the first reactor is regenerated with the oxidizing gas. By repeating this,
It is possible to continuously process coal gasification gas.
At the time of gas switching, there is a danger that the oxidizing gas and the reducing gas may be mixed and explode. Therefore, it is effective to purge with an inert gas (such as N ₂ ) before and after regeneration. SOx
Is supplied to an oxidation furnace and reacted with limestone to be fixed as gypsum, or separately supplied to SOx processing equipment such as S manufacturing equipment and sulfuric acid manufacturing equipment. The present embodiment is not limited to the case of two reactors as shown in FIG. 6, and it is also possible to perform simultaneous denitration and desulfurization continuously while repeating denitration and desulfurization and regeneration sequentially using more reactors. it can.

Embodiment (Part 3) FIG. 7 is a schematic diagram of a system according to this embodiment. In the present embodiment, in the above embodiment (No. 2), instead of the fixed bed reactor filled with the Ni-based catalyst,
The reactor is a moving bed reactor 201 as shown in FIG.
A Ni-based catalyst is continuously charged from the upper portion of the moving bed reactor 201, and after desulfurization and denitration, discharged from the lower portion. In the present embodiment, the discharged Ni-based catalyst is supplied to the moving bed regenerating device 202, and the regeneration gas 205 is supplied to perform the oxidative regeneration. The gas containing SOx after the regeneration is discharged through the regeneration gas outlet 206. The Ni-based catalyst whose desulfurization activity has been recovered by regeneration is fed into the reactor 201 again through the circulation line 204. At the time of re-feeding, fresh Ni-based catalyst is applied as make-up 203 only for the shortage due to non-regeneration or wear.

The operation and effect of the system according to the above-described embodiments (part 2) and (part 3) will be specifically described based on FIG. In the conventional system shown in FIG. 2, limestone fed to the desulfurization furnace 2, Scheme I CaC0 ₃ → CaO + C0 ₂ Scheme _{II CaO + H 2 S → CaS} + H 2 O, CaO + COS → CaO + CO _By a series of reactions shown in Reactions I and II of ₂ , H ₂ S and COS generated during coal gasification can be desulfurized to about 100 ppm.

On the other hand, in the system of the present invention shown in FIG. 6, the reaction VI NiO + H ₂ S → NiS + H ₂₀ is performed in a fixed bed reactor using a Ni-based catalyst mainly composed of NiO downstream of limestone desulfurization. The desulfurization reaction shown in Reaction VI proceeds. As shown in FIG.
The equilibrium H ₂ S concentration of NiO at the temperature at which the desulfurization furnace is operated and the partial pressure of steam is 0.003 ppm, and the H ₂ S concentration at the outlet of the desulfurization furnace which cannot be reached by the conventional desulfurization of only limestone 1
0 ppm or less can be achieved. Assuming that H ₂ S + COS
= 10 ppm, the present system allows the SOx concentration at the gas turbine outlet to be about 2 ppm. Also in the present embodiment, it is possible to use a Ni-based catalyst and limestone in combination, for example, to perform crude desulfurization to about 100 ppm with limestone, and to perform precise desulfurization from 100 ppm to about 10 ppm with a Ni-based catalyst. According to such a method, there is an advantage that the usage amount of the Ni-based catalyst can be reduced as compared with desulfurization using only the Ni-based catalyst.

On the other hand, as in the case of the first embodiment, the NH ₃ generated during coal gasification is decomposed by the following reaction VII due to the NH ₃ decomposition activity inherent in the Ni-based catalyst. Reaction VII NiS generated during the desulfurization of NH ₃ → N ₂ + 3H ₂ is oxidized in the regeneration
It becomes iO, and the desulfurization ability can be restored again. The oxidation reaction, the following reaction VII, but IX is considered, NiS0 ₄ 8
Above 40 ° C., it decomposes and releases SO ₂ , so the reaction VII
Only the oxidation reaction of I to NiO proceeds. The reaction _{VIII NiS + 3/20 2 → NiO +} S0 2 reaction IX NiS + 20 ₂ → NiS0 ₄

That is, the Ni-based catalyst, which has become desulfurized by becoming NiS due to the desulfurization reaction, switches the gas to 0 ₂
By flowing an oxidizing regenerating gas containing Ni, the NiO is regenerated and the desulfurization ability is restored again. Gas containing S0 ₂ to be released upon regeneration was put into an oxidation furnace, Ca
How O to be absorbed to immobilized as CAS0 ₄ (gypsum) and are considered. The method for immobilizing the sulfur component in the system of the present invention is not limited to this method, and other methods include reduction and recovery as sulfur, and sulfuric acid recovery.

[0030]

According to the denitrification desulfurization system of the present invention, the desulfurization rate in the desulfurization furnace can be improved without adding a complicated device, and N
By decomposing H ₃ , the load on the denitration device can be reduced or the denitration device itself can be made unnecessary. That is, according to the system of the present invention, the desulfurization reaction proceeds by introducing a Ni-based catalyst containing NiO as the main component into the desulfurization furnace at the same time as limestone, so that H ₂ S that cannot be achieved by the conventional desulfurization of limestone alone is used. A concentration of 10 ppm or less can be achieved, and the SOx concentration at the gas turbine outlet can be about 2 ppm. Then, in the system of the present invention, the crude desulfurization can be performed with limestone and the precision desulfurization can be performed with the Ni-based catalyst by using the Ni-based catalyst and limestone in combination, whereby the desulfurization can be carried out economically and efficiently.

Further, according to the present invention, it is not necessary to provide a separate denitration apparatus for removing NOx converted from NH ₃ generated in the gasification furnace by decomposition of NH ₃ by the Ni-based catalyst, and the denitration can be performed at low cost. It can be performed. Furthermore, in the present invention, since limestone can be used for desulfurization at around 950 ° C., there is no need to cool the temperature of coal gasification gas, and when used as a power generation system, the efficiency is high, and inexpensive limestone and a recycled Ni-based catalyst are used. And low cost. The present invention is a system that can sufficiently cope with a low required SOx concentration in the future.
It is expected that it can be suitably used as a power plant near an urban area in Japan.

[Brief description of the drawings]

FIG. 1 is a configuration diagram schematically showing a system according to an embodiment (first) of the present invention.

FIG. 2 is a configuration diagram schematically showing a conventional system.

FIG. 3 is a diagram showing the temperature dependence of the equilibrium H ₂ S concentration representing the desulfurization ability of a desulfurization material.

FIG. 4 is a diagram showing the temperature dependence of the ammonia decomposition rate of a Ni-based catalyst.

FIG. 5 is a configuration diagram illustrating an example of a Ni-based catalyst separation and recovery device.

FIG. 6 is a configuration diagram schematically showing a system including a fixed-bed reactor according to the embodiment (No. 2) of the present invention.

FIG. 7 is a configuration diagram schematically showing a system including a moving bed reactor according to an embodiment (part 3) of the present invention.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 coal gasifier 2 desulfurizer 3 oxidizer 4 cyclone 5 gas cooler 6 dust remover 7 gas turbine combustor 8 gas turbine 9 air compressor 10 exhaust gas boiler 11 denitrifier 12 chimney 13 steam turbine 14 limestone supply pipe 15 gas Coal supply pipe for gasifier 16 Air supply pipe for gasifier 17 Coal supply pipe for oxidation furnace 18 Air supply pipe for oxidation furnace 19 Char discharge pipe (residue of coal gasification) 20 Desulfurizer discharge pipe (Ni-based catalyst, CaS , CaO, C
aC0 _3, CaSO _4, a mixture of char) 21 cyclone recovery ash transport pipe (CaS, CaO, Ca
C0 _3, CaSO _4, mixture) 22 oxidizing furnace discharge pipe of discharging ash char (Ni-based catalyst, CaO, C
aC0 _3, CaS0 _4, mixture) 23 Ni-based catalyst separation and recovery device 24 Ni catalyst charging hopper 25 Ni catalyst injection tube 26 Ni catalyst makeup tube 27 Ni catalyst withdrawal pipe other coal-derived ash (Ni-based catalyst re supply pipe) 28 ash discharge pipe _{(CaO, CaC0 3, CaS0 4} , other mixtures coal from ash) 29 separation and recovery device fluidizing air _{30 CaO, CaC0 3, CaS0 4} , a mixture of other coal-derived ash 31 Ni catalysts Particle 101 Ni-based catalyst fixed bed reactor 102 Regenerating gas inlet 103 Regenerating gas outlet 201 Ni-based catalyst moving bed reactor 202 Moving bed regenerating device 203 Fresh Ni-based catalyst input port 204 Ni-based catalyst circulation line 205 Regenerating gas inlet 206 Regenerating gas exit

Continued on the front page (72) Inventor Yoshihiko Tsuchiyama 5-717-1, Fukabori-cho, Nagasaki-shi, Nagasaki F-term in Nagasaki Research Laboratory, Mitsubishi Heavy Industries, Ltd. 3K065 TA01 TA02 TB02 TB18 TB19 TC01 TC10 TD06 TF10 TG05 TK01 TK05

Claims (9)

[Claims] 1. A simultaneous denitration and desulfurization system comprising a gasification furnace, a desulfurization furnace, and an oxidation furnace, wherein a Ni-based catalyst containing NiO as a main component and limestone are charged into the desulfurization furnace. 2. The catalyst put into the desulfurization furnace is oxidized and regenerated in the oxidizing furnace, and a ash treatment system from the oxidizing furnace is provided with a catalyst separating and recovering device. 2. The simultaneous denitration and desulfurization system according to claim 1, wherein the denitrification is separated and recovered and re-input to a desulfurization furnace. 3. The method according to claim 1, wherein the catalyst separation and recovery device uses a fluidized bed at normal pressure, and extracts only the Ni-based catalyst particles having a large specific gravity from the furnace bottom by a gentle fluidized bed near the fluidization start speed. Item 3. A simultaneous denitration and desulfurization system according to Item 2. Wherein a supported catalyst in which the Ni-based catalyst is mainly composed of NiO, support said supported catalyst is Si0 _2, A1 ₂ 0
_3. The simultaneous denitration and desulfurization system according to claim 1, wherein the system is made of at least one oxide selected from the group consisting of MgO and MgO or a natural mineral containing them as a main component. 5. An integrated coal gasification combined cycle system comprising the simultaneous denitration and desulfurization system according to claim 1. Description: 6. A simultaneous denitration and desulfurization system comprising a gasification furnace, a desulfurization furnace, and an oxidation furnace, wherein a fixed-bed reactor using a Ni-based catalyst containing NiO as a main component is installed downstream of the desulfurization furnace. . 7. The denitrification and desulfurization performance of a reactor in which two or more fixed bed reactors are connected in parallel, a coal gasification gas and a regeneration gas are separately supplied to each reactor, and the coal gasification gas is supplied to the reactors. 7. The simultaneous denitration and desulfurization system according to claim 6, wherein the gas supplied to each of the reactors is switched at a stage where the temperature decreases, and the denitration and desulfurization is continuously performed while sequentially repeating the denitration and desulfurization and the regeneration in each of the reactors. 8. In a system having a gasification furnace, a desulfurization furnace, and an oxidation furnace, a moving bed reactor and a moving bed regeneration device using a Ni-based catalyst containing NiO as a main component are installed downstream of the desulfurization furnace. Simultaneous denitration and desulfurization system. 9. An integrated coal gasification combined cycle system comprising the simultaneous denitration and desulfurization system according to claim 6. Description: