JP2000111032A - Coal gasifying composite power generation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coal gasifying composite power generation system having an excellent reducing capability of SOx concentration value in an exhaust gas. SOLUTION: In the coal gasifying composite power generation system comprising a coal partial oxidizing furnace 1, an oxidizing furnace 2, a desulfurizing furnace 3 for removing a sulfur component in a coal gasified gas, a gas turbine 4 supplied with the obtained gas as a fuel, and an exhaust heat recovering unit 5 for recovering exhaust heat from the exhaust gas from the turbine; a secondary desulfurizing unit 6 is disposed at a tail flow of the unit 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an integrated coal gasification combined cycle system.

[0002]

2. Description of the Related Art In order to improve the power generation efficiency of a coal-fired power plant, the development of an integrated coal gasification combined cycle power generation system using a highly pressurized fluidized bed combustion system has been promoted. Such a power generation system includes a coal partial oxidation furnace (coal gasification furnace), a desulfurization furnace, an oxidation furnace (PFBC: pressurized fluidized bed combustion furnace), a dust removal device, a gas turbine, a steam turbine, a denitration device, and the like. ing. In such a system, carbon in coal,
When gasifying hydrogen as carbon monoxide, carbon dioxide, hydrogen, and water vapor, sulfur contained in coal is mixed into the gasified gas as hydrogen sulfide (H ₂ S) or carbonyl sulfide (COS). Conventionally, as a countermeasure against this, a desulfurization furnace was installed downstream of a coal gasification furnace (partial oxidation furnace), and limestone desulfurization was performed to remove sulfur.

[0003] In a system using such a desulfurization furnace, the total concentration of H ₂ S and COS at the outlet of the desulfurization furnace can be removed only up to about 100 ppm, and the SO _x concentration downstream of the gas turbine is reduced. It is about 50 ppm. If a lower concentration of SO _x concentration is required for future use as a power plant near an urban area in Japan,
The desulfurization performance was not sufficiently satisfactory.

[0004]

For the present invention is the situation [0005] relates to SO _x concentration value in the exhaust gas, and an object thereof is to provide a coal gasification combined cycle system with excellent reduction ability.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a partial oxidation furnace for coal, an oxidation furnace, a desulfurization furnace for removing sulfur from coal gasification gas, and a method for removing the obtained gas. In a coal gasification combined cycle system including a gas turbine supplied as fuel and an exhaust heat recovery device that recovers exhaust heat from exhaust gas from the gas turbine, a secondary desulfurization device is disposed downstream of the exhaust heat recovery device. It is characterized by the following. In the present invention, the secondary desulfurization device can be a limestone-gypsum method desulfurization device including an absorbing section and an oxidizing section. In the present invention, an ACF desulfurizer using activated carbon fibers can be employed as the secondary desulfurizer.

[0006] Further, the secondary desulfurization unit is an activated carbon adsorption tower.
And a regeneration tower. In that case,
SO from regeneration tower_xIt is preferable to return
Suitable. In addition, the secondary desulfurization unit is equipped with an activated carbon adsorption tower and a regeneration tower.
And the SO from the regeneration tower_xLime to be introduced
The provision of a stone-gypsum desulfurization apparatus is also included in the present invention.
On the other hand, the secondary desulfurization unit consists of an activated carbon adsorption tower and a regeneration tower.
And the SO from the regeneration tower _xConverter for oxidizing
And the resulting SO_ThreeFurther includes a recovery tower for recovering
This is also included in the present invention. In yet another form, the shape
Desulfurization equipment for chars discharged from a state coal partial oxidation furnace
Introduced to SO_xThe char adsorbed in the oxidation furnace
This is also included in the present invention. And yet another
As a form, it further includes an activation device for activating coal.
Activated coal is introduced into the secondary desulfurization unit,_xAdsorbed
In the present invention, it is possible to supply
include.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an integrated coal gasification combined cycle system according to the present invention will be described with reference to the embodiments shown in the accompanying drawings.

[0008] A secondary desulfurization unit is provided by the limestone-gypsum method.
Embodiment (First Embodiment) FIG. 1 shows a first embodiment of an integrated coal gasification combined cycle system according to the present invention. This embodiment is of a type in which a secondary desulfurization device is disposed downstream of an exhaust heat recovery device that recovers exhaust heat from exhaust gas from a gas turbine. As shown in FIG. 1, the integrated coal gasification combined cycle system according to the present invention includes a coal partial oxidation furnace 1, an oxidation furnace 2, a desulfurization furnace 3, a gas turbine 4, an exhaust heat recovery device 5, a secondary desulfurization device (desulfurization tower). 6) and chimney 7.

First, the main components included in the present embodiment will be outlined. Coal partial oxidation furnace (gasification furnace) 1
Is a furnace for converting coal into coal gasification gas.
That is, in the furnace 1, the coal and the char produced therefrom are used as fluidizing particles, and the combustion gas and the oxidizing gas (generally, air) from the oxidizing furnace 2 are used as the fluidizing gas. A fluidized bed is formed by these particles and the gas. Then, a part of the coal is burned by oxygen contained in the oxidizing furnace combustion gas and the oxidizing gas. The coal is converted into a coal gasified gas by the carbon dioxide and steam generated by the combustion and the carbon dioxide and steam in the oxidation furnace combustion gas. Note that the char is a carbonaceous porous material remaining when gasifying coal.

[0010] The desulfurization furnace 3 is a furnace for fixing and desulfurizing the sulfur content in the coal gasification gas as CaS in limestone. The fluidized bed is connected to the coal partial oxidation furnace 1 and uses the limestone charged as fluidization particles and the coal gasification gas introduced from the coal partial oxidation furnace 1 as a fluidization gas. , Fix the sulfur content in the gas. In the oxidation furnace 2, char is supplied from the coal partial oxidation furnace 1 and limestone is supplied from the desulfurization furnace 3.
While burning the char, the CaS is replaced with CaS
Was converted into O _4, heating water or water vapor in the heat exchanger 8 with a built-in reaction heat generated by them oxidation reactions, to deliver combustion gas after heat exchange to the coal partial oxidation furnace 1. An exhaust gas boiler 9 is generally used for the exhaust heat recovery device 5. Water or steam is heated by the waste heat of the combustion gas discharged from the gas turbine 4 and sent to the heat exchanger 9 of the oxidizing furnace 2. The gas turbine 4 burns the coal gasified gas in the combustor 11 with the air from the air compressor 10 and rotates by this. It is preferable that the gas turbine is compatible with coal gasification gas.

Further, in the first embodiment, a desulfurization tower 6 for performing desulfurization by a limestone-gypsum method is provided as a secondary desulfurization device downstream of the exhaust heat recovery device 5. This desulfurization tower 6
Includes a cooling unit 12, an absorbing unit 13, and an oxidizing unit 14. As such a desulfurization tower 6, there are conventionally various known ones.
There is no particular limitation as long as the object of the present invention is met. . The cooling unit 12 is a unit for adjusting the temperature of the exhaust gas to a temperature suitable for processing. It is unnecessary if the exhaust gas is introduced at a moderate temperature. This is provided when sufficient device efficiency cannot be obtained only by heat exchange in the gas gas heater 15.

Using limestone or slaked lime slurry as an absorbent, the absorption section 13 absorbs SO ₂ . The reaction is complicated, but the outline is as follows. Absorber 13
For example, water containing an absorbent is blown up from a spray nozzle and is brought into contact with downward exhaust gas to perform absorption. CaO + SO ₂ = CaSO ₃ CaCO ₃ + SO ₂ = CaSO ₃ + CO ₂ CaSO ₃ (lime sulphite) produced by the reaction is a fine crystal of 1-2 μm which is hardly soluble in water and has no use. Then, fine bubbles of air or oxygen are blown into the formed slurry in the oxidizing section 14 to oxidize the slurry and collect it as gypsum. The oxidizing unit 14 may be configured as an oxidizing tank provided below the absorbing unit 13. The reaction is as follows. _{CaSO 3 + 1 / 2O 2 +} 2H 2 O = CaSO 4 · 2H 2 O

Next, the operation of the integrated coal gasification combined cycle system according to the first embodiment will be described. First, when coal and an oxidizing gas (air) are supplied to the coal partial oxidation furnace 1, the coal is gasified in the partial oxidation furnace 1 by the oxygen in the oxidizing gas and the combustion gas from the oxidizing furnace 2. by this,
Converted to gasified gas and char. The generated char is sent to the oxidation furnace 2. Next, the gasification gas is supplied to the desulfurization furnace 3.
Sent to In the desulfurization furnace 3, limestone is supplied to form a fluidized bed of limestone, and the coal gasification gas plays a role of fluidizing gas in the fluidized bed. Here, the sulfur content (H ₂ S and COS) in the coal gasification gas contains Ca in the limestone.
S is fixed and desulfurization is performed. Limestone containing CaS which is a remaining desulfurizing agent is sent to the oxidation furnace 2. The amount of limestone withdrawn can be adjusted by a desulfurizing agent transfer device (not shown).

The coal gasified gas after desulfurization is cyclone 1
After passing through 6, it is sent to the gas cooler 17. Cyclone 16
Then, the CaS and the remaining char are separated and the oxidation furnace 2
Sent to In the oxidation furnace 2, mainly limestone (desulfurizing agent)
This forms a fluidized bed. As described above, char and limestone are supplied to the fluidized bed. The fluidized bed is fluidized by air and steam supplied from the furnace bottom. In the fluidized bed, char is rapidly converted to gas and ash by a combustion reaction, while char in limestone is changed.
Since aS is slowly converted to CaSO ₄ , the fluidized particles of the fluidized bed are mainly limestone. A heat exchanger 8 is installed on the free board of the oxidation furnace, and absorbs the heat of particles and gas soaring from the fluidized bed to maintain the temperature of the fluidized bed at an appropriate temperature (850 to 1050 ° C). In this temperature range, the reaction of converting CaS to CaSO ₄ occurs, and the reaction of reacting SO ₂ generated by the side reaction with CaO to form CaSO ₄ proceeds, and the ash and desulfurizing agent do not soften.

The combustion gas discharged from the oxidizing furnace 2 is sent to the coal partial oxidizing furnace 1 via the cyclone 18. In the cyclone 18, gypsum and ash are removed from the combustion gas. On the other hand, the coal gasified gas is cooled by a gas cooler 17 and then cooled by a ceramic filter 1 provided as a dust remover.
9 removes dust. Here, the temperature is about 450 ° C. Then, this gas is sent to the combustor 11 of the gas turbine 4. The combustor 11 burns the coal gasification gas with the air from the air compressor 10, and rotates the turbine on the expansion side.
Then, the exhaust gas is sent to the exhaust gas boiler 9, the denitration device 20, and the second exhaust gas boiler 21 that constitute the exhaust heat recovery device 5. Exhaust heat recovery is performed in the exhaust gas boilers 9 and 21,
The energy is recovered and used as a power source for a steam turbine (not shown) to generate power. In the denitration device 20, denitration from exhaust gas is performed according to a known method. The operation described above is
The same applies to other embodiments of the present invention, and the above description may be referred to in the following description.

The exhaust gas passing through the exhaust gas boiler has a temperature of about 130 ° C. This exhaust gas is introduced into the gas gas heater 15 and exchanges heat with the exhaust gas discharged from the desulfurization tower 6. That is, some cooling is performed. In addition, the gas gas heater 15 raises the desulfurization efficiency by sufficiently lowering the temperature of the exhaust gas in the previous stage of the desulfurization tower 6, suppresses the consumption of working water, and sufficiently raises the chimney inlet gas temperature to increase the processing gas diffusion efficiency. It is provided for the purpose of raising. Desulfurization tower 6
As described above, operations such as cooling of exhaust gas, absorption of sulfurous acid gas, and oxidation of sulphite lime are performed as described above.
Gypsum is recovered from 4. The exhaust gas after secondary desulfurization is about 5
Although the temperature is 0 ° C., the heat is
It reaches 0 ° C and is discharged from the chimney. Since the temperature is raised in this way, it does not become white smoke. As described above, SO _x <10 ppm can be achieved by the desulfurization tower 6 provided as a secondary desulfurization device downstream of the exhaust heat recovery device 5. That is, the coal gasification combined power generation system according to this embodiment relates to a SO _x concentration value in the exhaust gas, and thus with excellent reduction ability.

Secondary desulfurization equipment using activated carbon fiber (ACF)
Embodiment provided with an installation (second embodiment) FIG. 2 shows a second embodiment of the integrated coal gasification combined cycle system according to the present invention. This embodiment is also of a type in which a secondary desulfurization device is disposed downstream of an exhaust heat recovery device that recovers exhaust heat from exhaust gas from a gas turbine. In this embodiment, as a secondary desulfurization device, A made of activated carbon fiber is used.
Uses CF desulfurization equipment. In this embodiment, the same parts as those in FIG. 1 are denoted by the same reference numerals, and the description is used. In the present embodiment, an ACF desulfurization device 31 using an activated carbon fiber layer is provided downstream of the exhaust heat recovery device 5, a cooler 32 is provided upstream of the ACF desulfurization device, and a heater 33 is provided downstream.

The ACF desulfurization apparatus 31 has been developed by the present inventors as a simple desulfurization method that does not require a sulfur oxide absorbent or a large desulfurization facility. In the desulfurization device 31, the SO ₂ in the exhaust gas is oxidized into SO ₃ by contacting the activated carbon fiber for desulfurization reaction with water adhered to the surface, and the SO ₃ and water on the activated carbon fiber for desulfurization reaction are combined. To produce sulfuric acid. As the desulfurization catalyst, a catalyst in which a lattice having an integrally formed catalyst supporting grating structure is provided in a box container and a plurality of desulfurization catalyst elements are accommodated in a catalyst pack structure thus formed is preferable. As the desulfurization catalyst, a gas parallel flow catalyst in which the exhaust gas flows in the vertical direction is preferable. The gas parallel flow type is a method in which exhaust gas flows in parallel in a gas passage of a desulfurization catalyst, which is regularly formed and arranged in a lattice shape, a honeycomb shape, a plate shape, or the like. This method is suitable for preventing the catalyst from being clogged by dust.

Since oxygen (O ₂ ) is used to oxidize SO ₂ to SO ₃ during desulfurization, it is necessary to include oxygen in the exhaust gas or to separately supply oxygen to the exhaust gas. The content of oxygen in the exhaust gas is 3% to 21% by volume
It is as follows. As gas components other than SO ₂ and O ₂ , components such as nitrogen, carbon dioxide, and carbon monoxide can be generally included. The flow rate of the gas is usually about 0.2 to 1 liter / minute per unit weight of the activated carbon fiber for the desulfurization reaction. The generated SO ₃ becomes dilute sulfuric acid by the reaction with water supplied from the water spray nozzle and on the activated carbon fibers for the desulfurization reaction, and is stored in the lower part of the desulfurizer.

The activated carbon fiber for desulfurization reaction used in the present embodiment functions as a catalyst when SO _{2 in} the exhaust gas is oxidized to SO ₃ . A method for producing such an activated carbon fiber for desulfurization reaction will be described below. The type of activated carbon fiber used as a raw material is not particularly limited, and active carbon fibers such as pitch-based, polyacrylonitrile-based, phenol-based, and cellulose-based activated carbon fibers can be used. Among these, those having higher hydrophobicity on the surface of the activated carbon fiber are particularly desirable, and specific examples thereof include pitch-based activated carbon fiber.

Activated carbon fibers are usually heat-treated at a temperature of about 600 to 1200 ° C. in a non-oxidizing atmosphere such as nitrogen gas. The processing time may be appropriately determined according to the processing temperature and the like. By this heat treatment, carbon fibers for the desulfurization reaction used in the present embodiment can be obtained. Since the activated carbon fiber for desulfurization reaction has been partially or entirely removed as CO, CO ₂ or the like by a heat treatment, the hydrophilic oxygen functional groups have been removed.
The surface has a greater hydrophobicity than before the treatment. Therefore, it occurs readily snapping SO ₂ to oxidized active sites SO _2, yet produced results that discharge also proceeds rapidly sulfate, without the function of the catalyst is inhibited, the desulfurization reaction is accelerated.

A specific example of the production example of the activated carbon fiber for the desulfurization reaction is as follows, for example. Specific Example 1 A pitch-based activated carbon fiber (“OG-20A”, manufactured by Adol Co., Ltd.) was used in a nitrogen atmosphere at 900 to 1,
Baking is performed for 1 hour in a temperature range of 200 ° C. Specific Example 2 Polyacrylonitrile-based activated carbon fiber (“FE-30
0 "(manufactured by Toho Rayon Co., Ltd.) and fired in a nitrogen atmosphere within a temperature range of 800 to 1200 ° C. for 1 hour. The properties of the activated carbon fiber for desulfurization reaction used in the present embodiment are usually 7 to 20 μm in thickness and 5 to specific surface area.
00 to 2,500 m ² / g, outer surface area 0.2 to 2.0
m ² / g, and the pore diameter is 45 Å or less.

Next, the operation of the integrated coal gasification combined cycle system according to the second embodiment will be described. In the present embodiment, the exhaust gas is supplied at about 125 ° C. to the upstream of the cooler 32 through a procedure similar to that of the embodiment of FIG. The exhaust gas is cooled by the cooler 32 to a temperature of 90 to 100 ° C. Then, in the ACF desulfurization device 31, the SCF in the exhaust gas is brought into contact with activated carbon fibers for desulfurization reaction having water adhered to the surface.
The O ₂ causes oxidized to SO _3, to produce a sulfuric acid by reaction with the SO ₃ and desulfurization reaction activated carbon fibers on the water. Then, the sulfuric acid is recovered. ACF desulfurizer 31
The exhaust gas that has passed through is about 50 ° C., which is heated by the heater 33 and discharged at about 110 ° C. Since the temperature is raised in this way, it does not become white smoke.

As described above, the ACF desulfurization unit 31 provided as a secondary desulfurization unit provided downstream of the exhaust heat recovery unit 5
As a result, SO _x <10 ppm can be achieved. That is, the coal gasification combined power generation system according to this embodiment relates to a SO _x concentration value in the exhaust gas, and thus with excellent reduction ability. Also, there is an effect that sulfuric acid can be obtained as a by-product. The resulting sulfuric acid can be recovered or sprayed onto ash to gypsum.

Secondary desulfurization consisting of activated carbon adsorption tower and regeneration tower
Embodiment with Apparatus (Third Embodiment) FIG. 3 shows a third embodiment of the integrated coal gasification combined cycle system according to the present invention. This embodiment is also of a type in which a secondary desulfurization device is disposed downstream of an exhaust heat recovery device that recovers exhaust heat from exhaust gas from a gas turbine. In this embodiment, a desulfurization apparatus including an activated carbon adsorption tower 41 and a regeneration tower 42 is used as a secondary desulfurization apparatus. In this embodiment, the same parts as those in FIG. 1 are denoted by the same reference numerals, and the description is used.

In the present embodiment, SO ₂ in the exhaust gas is adsorbed on the activated carbon contained in the activated carbon adsorption tower 41. SO ₂
The activated carbon adsorbed is sequentially sent to the regeneration tower 42. That is, it falls to the regeneration tower side by weight. Regeneration tower 42
, An inert gas such as nitrogen is introduced as a regeneration gas. The gas containing SO ₂ is sent to the oxidizing furnace 2 and used as oxidizing gas for coal. The sulfur content in SO ₂ is finally recovered as gypsum. The activated carbon regenerated in the regeneration tower 42 is sent to the adsorption tower 41 again and reused. Note that a certain amount of fresh activated carbon is also appropriately replenished.

Activated carbon not only adsorbs SO _x but also adsorbs NO _x . Therefore, in the present embodiment, ammonia is added to the exhaust gas in advance. As a result, the SO _x removal rate is increased, and N
The removal rate of O _x is also increased. Note that the addition of various metal compounds to activated carbon further increases the NO _x removal rate. In the present embodiment, a dust removing device 43 is provided to remove dust generated by the treatment with activated carbon. As described above, SO _x <10 ppm by the secondary desulfurization device provided at the subsequent stage of the exhaust heat recovery device.
It can be. That is, the coal gasification combined power generation system according to this embodiment relates to a SO _x concentration value in the exhaust gas, and thus with excellent reduction ability. In addition, it is possible not only to improve the desulfurization performance by returning SO ₂ to the oxidizing furnace 2 but also to improve the efficiency of the entire apparatus.

Secondary desulfurization consisting of activated carbon adsorption tower and regeneration tower
Limestone-gypsum method for desulfurizing regeneration gas from equipment
Embodiment provided with desulfurization device (fourth embodiment) FIG. 4 shows a fourth embodiment of the integrated coal gasification combined cycle system according to the present invention. This embodiment is also of a type in which a secondary desulfurization device is disposed downstream of an exhaust heat recovery device that recovers exhaust heat from exhaust gas from a gas turbine. In this embodiment, a desulfurization device comprising an activated carbon adsorption tower and a regeneration tower was used as a secondary desulfurization device, and a limestone-gypsum method desulfurization device for desulfurizing regeneration gas was provided. In this embodiment, the same parts as those in FIG. 1 are denoted by the same reference numerals, and the description is used.

This embodiment is the same as the third embodiment.
In the activated carbon adsorption tower 41, SO _TwoAnd then re-adsorb
SO in the live tower 42_TwoDesorption of water to regenerate activated carbon
You. In the present embodiment, the SO gas in the regeneration gas_TwoExcluding
Limestone-gypsum method
A desulfurization tower 51 for performing desulfurization is provided. This desulfurization tower 51
Includes a cooling unit 52, an absorbing unit 53, and an oxidizing unit 54;
This is similar to the embodiment. . In the desulfurization tower 51,
As described above for the first embodiment, the cooling of exhaust gas
Operations such as sulphite gas absorption and sulphite lime oxidation
Is performed, and gypsum is collected from the oxidizing unit 54. And
The gas from the absorber 53 was removed by the dust remover 43.
Later, it is discharged from the chimney 7.

Activated carbon has the property of adsorbing NO _{x as} well as adsorbing SO _x . Therefore, also in the present embodiment, ammonia is added to the exhaust gas in advance. As a result, the SO _x removal rate is increased, and N
The removal rate of O _x is also increased. Note that the addition of various metal compounds to activated carbon further increases the NO _x removal rate. As described above, SO _x <10 ppm can be achieved by the secondary desulfurization device provided downstream of the exhaust heat recovery device. That is, the coal gasification combined power generation system according to this embodiment relates to a SO _x concentration value in the exhaust gas, and thus with excellent reduction ability. Further, in the present embodiment, the SO ₂ once adsorbed by the activated carbon is treated, and the SO ₂ concentration in the regeneration gas is much higher than that of the exhaust gas immediately after the exhaust heat recovery device. It can be implemented on a much smaller scale than the desulfurization tower of the form (1).

Secondary desulfurization consisting of activated carbon adsorption tower and regeneration tower
Device and oxidizes SO _x in the regeneration gas from this device
And a recovery tower for recovering SO ₃
Embodiments Including Further (Fifth Embodiment) FIG. 5 shows a fifth embodiment of the integrated coal gasification combined cycle system according to the present invention. This embodiment is also of a type in which a secondary desulfurization device is disposed downstream of an exhaust heat recovery device that recovers exhaust heat from exhaust gas from a gas turbine. In this embodiment, a desulfurization apparatus including an activated carbon adsorption tower and a regeneration tower is used as a secondary desulfurization apparatus, and further, SO _x in the regeneration gas is used.
And a recovery tower for recovering SO ₃ . In this embodiment, the same parts as those in FIG. 1 are denoted by the same reference numerals, and the description is used.

This embodiment is the same as the third embodiment.
In the activated carbon adsorption tower 41, SO _TwoAnd then re-adsorb
SO in the live tower 42_TwoDesorption of water to regenerate activated carbon
You. The activated carbon is SO_xNot only adsorb
NO_xAlso has the property of adsorbing. Therefore, in this embodiment,
Also pre-add ammonia to the exhaust gas. to this
So SO_xNO removal rate and NO_xRemoval rate
Is also increasing. In addition, various metal compounds are added to activated carbon.
NO by_xRemoval rate is further increased. Form of this implementation
In the state, SO in the regeneration gas_TwoTo oxidize
Inverter 61 and the resulting SO_ThreeCollection to collect
A tower 62 is provided. Converter 61 is a vanadium pentoxide
Converter book filled with a catalyst mainly composed of
Increase the gas temperature to the temperature required for the reaction between the body and the converter
It consists of a heat exchanger for raising. Converter book
In the body, on the catalyst surface, SO_Two+1/20_Two= SO_Three The reaction of SO_TwoIs oxidized to SO_ThreeConvert to reaction
The oxygen required for the gas is the oxygen concentration in the gas, SO_TwoDepends on concentration
Where air needs to be supplied so that
In some cases. SO_ThreeThe reaction gas containing
After being cooled by the heat exchanger of
You. The recovery tower 62 is filled with Raschig rings, for example, and
And spray water from the bottom of the tower
SO_ThreeIs supplied by the following reaction. SO_Three+ H_TwoO = H_TwoSO_Four Water can be circulated and used to increase sulfuric acid concentration.
You.

In the present embodiment, converter 61 uses SO
₂ is oxidized to SO _3, and water is added thereto to recover sulfuric acid in a recovery tower 62, or the obtained sulfuric acid is sprayed on ash.
3 and fixed as gypsum, and can be disposed of or otherwise treated. The gas from the recovery tower 62 is discharged from the chimney 7 via the dust removing device 43. As described above, the secondary desulfurization device provided at the subsequent stage of the exhaust heat recovery device allows the SO _x
<10 ppm. That is, the coal gasification combined power generation system according to this embodiment relates to a SO _x concentration value in the exhaust gas, and thus with excellent reduction ability. Further, in this embodiment, once or obtain sulfuric acid processes the SO ₂ adsorbed by the activated carbon, it is possible to effectively utilize the like, the final product to be used for ash treatment.

Secondary desulfurization consisting of activated carbon adsorption tower and regeneration tower
In addition to the equipment, the reactor further includes a coal reduction furnace and a Claus furnace.
Embodiment (Sixth Embodiment) FIG. 6 shows a sixth embodiment of the integrated coal gasification combined cycle system according to the present invention. This embodiment is also of a type in which a secondary desulfurization device is disposed downstream of an exhaust heat recovery device that recovers exhaust heat from exhaust gas from a gas turbine. In this embodiment, a desulfurization apparatus including an activated carbon adsorption tower and a regeneration tower is used as a secondary desulfurization apparatus, and further includes a coal reduction furnace and a Claus furnace. In this embodiment, the same parts as those in FIG. 1 are denoted by the same reference numerals, and the description is used.

This embodiment is the same as the third embodiment.
In the activated carbon adsorption tower 41, SO _TwoAnd then re-adsorb
SO in the live tower 42_TwoDesorption of water to regenerate activated carbon
You. The activated carbon is SO_xNot only adsorb
NO_xAlso has the property of adsorbing. Therefore, in this embodiment,
Also pre-add ammonia to the exhaust gas. to this
So SO_xNO removal rate and NO_xRemoval rate
Is also increasing. In addition, various metal compounds are added to activated carbon.
NO by_xRemoval rate is further increased.

In the present embodiment, a coal reduction furnace 71 and a Claus furnace 72 are further included. In the present embodiment, SO ₂
A small amount of air is mixed with a regeneration gas containing, and the mixture is introduced into the lower part of a coal reduction furnace 71 filled with coal, and the inside of the furnace is maintained at 700 ° C by partial combustion of coal to cause the next reaction. _{C + H 2 O = H 2} + CO C + SO 2 = about 90% of the _{S + CO 2 H 2 + S} = H 2 S CO + S = COS SO 2 reacts in the coal reduction furnace 71, 45%
Is S, 30% is H ₂ S, and 10% is COS. This gas is cooled to separate S (sulfur), and then the Claus furnace 7
Sent to 2.

The Claus furnace is a method for producing sulfur S by the reaction of hydrogen sulfide H ₂ S and SO ₂ .
In the reaction (a), a catalyst such as bauxite containing iron is used, and two or three Claus furnaces are connected to complete the reaction. In _{2H 2 S + SO 2 = 2H} 2 O + 3S (a) COS + H 2 O = H 2 S + CO 2 (b) Claus furnace 72, almost all of the H ₂ S and COS becomes S. Actually, a part of SO ₂ is also put into the Claus furnace 72 to adjust the H ₂ S / SO ₂ ratio. Also in this embodiment, the exhaust gas that has passed through the adsorption tower is discharged from the chimney through the dust remover.

As described above, SO _x <10 ppm can be achieved by the secondary desulfurization device provided downstream of the exhaust heat recovery device. That is, the coal gasification combined power generation system according to this embodiment relates to a SO _x concentration value in the exhaust gas, and thus with excellent reduction ability. Further, in the present embodiment, there is an advantage that S can be obtained by treating SO ₂ once adsorbed by activated carbon.

The char discharged from the coal partial oxidation furnace is
Embodiment (Seventh embodiment)
FIG. 7 shows a seventh embodiment of the integrated coal gasification combined cycle system according to the present invention. This embodiment is also of a type in which a secondary desulfurization device is disposed downstream of an exhaust heat recovery device that recovers exhaust heat from exhaust gas from a gas turbine. In this embodiment, the char discharged from the partial oxidation furnace is led to the secondary desulfurization device. Each component in FIG. 7 uses a slightly different notation from FIG. However, the same parts as those of FIG. In the present embodiment, the discharged char is sent not to the oxidation furnace 2 but to the secondary desulfurization device. Char is
It is produced by gasifying part of coal in the partial oxidation furnace 1. Therefore, it can be used as a porous carbon material. The present inventors have paid attention to this point.

In the present embodiment, the char is sent to the secondary desulfurization device 82 via the line 81 to adsorb SO ₂ and then sent to the oxidation furnace 2 via the line 83. In the oxidation furnace 2, the char burns, and the adsorbed SO ₂ becomes C ₂
It is recovered as aSO _4. The secondary desulfurization device 82
Is constituted by, for example, a moving bed reactor, in which the char is continuously supplied from the upper part of the apparatus, and the char having adsorbed SO ₂ is sequentially taken out from the lower part of the apparatus. The gas is supplied from the lower part of the secondary desulfurization device 82, and is discharged from the upper part of the device after being desulfurized by the char. A dust removal device can be attached downstream of the secondary desulfurization device 82 as needed.

The numerical values shown in FIG. 7 indicate data in a state where this embodiment is actually operated.
The combustion temperature of the partial oxidation furnace 1 is 1173 to 1373 K
And coal is supplied at 104 t / h. CaCO ₃ is supplied to the generated coal gasification gas in the desulfurization furnace 3 at a rate of 3.7 h / h. At the outlet of the denitration device 20, the exhaust gas has the following properties. Exhaust gas temperature 130 ° C Pressure 1.1ata SO _x 30 ppm NO _x 30 ppm CO ₂ 7.3% O ₂ 11.88% N ₂ 75.8%

The exhaust gas is sent to the secondary desulfurizer 82 at a rate of 1.8 × 10 ⁶ Nm ³ / h. From partial oxidation furnace 1, 2
Send char at a rate of 0 ton / h. Although these numerical values are merely examples, the intended function can be obtained under such specifications. As described above, the secondary desulfurization device 82 provided at the subsequent stage of the exhaust heat recovery device allows SO _x <1
It can be 0 ppm. That is, the integrated coal gasification combined cycle system according to this embodiment has
With respect to the O _x concentration value, it will have excellent lowering ability. Further, the present embodiment has an advantage that the char can be positively utilized as an adsorbent, and the secondary desulfurization apparatus does not require a separate adsorbent from outside the system.

The activated coal is to be introduced into a secondary desulfurization unit.
Eighth Embodiment FIG. 8 shows an eighth embodiment of the integrated coal gasification combined cycle system according to the present invention. This embodiment is also of a type in which a secondary desulfurization device is disposed downstream of an exhaust heat recovery device that recovers exhaust heat from exhaust gas from a gas turbine. In this embodiment, activated coal supplied from the coal activation device is guided to the secondary desulfurization device. The components in FIG. 8 use notations slightly different from those in FIG. However, the same parts as those of FIG.

The activated coal can be used as a carbonaceous adsorbent. The present inventors have paid attention to this point. In the present embodiment, the coal is activated by the activation device 91. The activation device 91 partially decomposes the coal at a predetermined temperature in an inert gas atmosphere to give the coal an SO ₂ adsorption ability. The activation device 91 may be either a moving bed or a fluidized bed reactor, and continuously supplies coal, and the activated coal is continuously taken out and supplied to the secondary desulfurization device 93.
The gas discharged from the activation device 91 is a volatile component in coal,
Gases such as CO and CO ₂ generated by thermal decomposition are supplied to a partial oxidation furnace. The activated coal is sent to a secondary desulfurization unit 93 via a line 92 to adsorb SO ₂ ,
4 to the partial oxidation furnace 1. Partial oxidation furnace 1
In the above, the activated coal is partially oxidized together with the directly input coal. Note that the secondary desulfurization device 93 is configured by, for example, a moving bed reactor, in which activated coal is continuously supplied from the upper portion of the device, and activated coal after adsorbing SO ₂ is sequentially extracted from the lower portion of the device. The gas is supplied to the secondary desulfurizer 93
It is supplied from the lower part and discharged from the upper part of the device after being desulfurized by activated coal. A dust removal device can be attached downstream of the secondary desulfurization device 93 as needed.

As described above, SO _x <10 ppm can be achieved by the secondary desulfurization device provided downstream of the exhaust heat recovery device. That is, the coal gasification combined power generation system according to this embodiment relates to a SO _x concentration value in the exhaust gas, and thus with excellent reduction ability. Furthermore, in the present embodiment, activated coal is used as an adsorbent, and the secondary desulfurization apparatus has an advantage that no additional adsorbent is required.

[0046]

According to the coal gasification combined power generation system of the present invention, the SO _x concentration in the chimney outlet gas it is possible to 10ppm or less, it is possible to implement good environmental measures.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a first embodiment of an integrated coal gasification combined cycle system according to the present invention.

FIG. 2 is a conceptual diagram showing a second embodiment of the integrated coal gasification combined cycle system according to the present invention.

FIG. 3 is a conceptual diagram showing a third embodiment of the integrated coal gasification combined cycle system according to the present invention.

FIG. 4 is a conceptual diagram showing a fourth embodiment of the integrated coal gasification combined cycle system according to the present invention.

FIG. 5 is a conceptual diagram showing a fifth embodiment of the integrated coal gasification combined cycle system according to the present invention.

FIG. 6 is a conceptual diagram showing a sixth embodiment of the integrated coal gasification combined cycle system according to the present invention.

FIG. 7 is a conceptual diagram showing a seventh embodiment of the integrated coal gasification combined cycle system according to the present invention.

FIG. 8 is a conceptual diagram showing an eighth embodiment of the integrated coal gasification combined cycle system according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Coal partial oxidation furnace 2 Oxidation furnace 3 Desulfurization furnace 4 Gas turbine 5 Exhaust heat recovery apparatus 6 Desulfurization tower 7 Chimney 8 Heat exchanger 9 Exhaust gas boiler 10 Air compressor 11 Combustor 12 Cooling part 13 Absorption part 14 Oxidation part 15 Gas gas heater Reference Signs List 16 cyclone 17 gas cooler 18 cyclone 19 ceramic filter 20 denitrifier 21 exhaust gas boiler 31 ACF desulfurizer 32 cooler 33 heater 41 adsorption tower 42 regeneration tower 43 dust remover 51 desulfurization tower 52 cooling section 53 absorption section 54 oxidation section 61 converter 62 Recovery tower 71 Coal reduction furnace 72 Claus furnace 81, 83 line 82 Secondary desulfurization unit 91 Activation unit 92, 94 line 93 Secondary desulfurization unit

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F01K 23/10 B01D 53/34 123B F23B 5/00 301 125E (72) Inventor Akinori Yasutake Fukahori, Nagasaki City, Nagasaki Prefecture 5-717, Machi Nagasaki R & D Co., Ltd. F-term (Reference) 3G081 BA13 BC07 DA22 DA30 3K046 AA01 AB01 AC01 CA08 CA10 EA03 FA06 3K070 DA02 DA03 DA14 DA15 DA23 DA26 DA81 4D002 AA02 AA03 AA04 AC10 BA02 BA04 BA05 DA05 DA12 DA16 DA44 DA66 EA08 EA13 FA03 FA08

Claims (9)

[Claims] 1. A coal partial oxidation furnace, an oxidation furnace, a desulfurization furnace for removing sulfur from coal gasification gas, a gas turbine supplied with the obtained gas as fuel, and waste heat from exhaust gas from the gas turbine. An integrated coal gasification combined cycle system including a waste heat recovery unit that performs recovery, wherein a secondary desulfurization unit is disposed downstream of the exhaust heat collection unit. 2. The integrated coal gasification combined cycle system according to claim 1, wherein said secondary desulfurization device is a limestone-gypsum method desulfurization device including an absorption section and an oxidation section. 3. The integrated coal gasification combined cycle system according to claim 1, wherein said secondary desulfurization unit is an ACF desulfurization unit using activated carbon fibers. 4. The integrated coal gasification combined cycle system according to claim 1, wherein said secondary desulfurization unit comprises an activated carbon adsorption tower and a regeneration tower. 5. The integrated coal gasification combined cycle system according to claim 4, wherein SO _x from said regeneration tower is returned to an oxidation furnace. 6. The integrated coal gasification combined cycle system according to claim 4, further comprising a limestone-gypsum desulfurization apparatus into which SO _x from the regeneration tower is introduced. 7. The integrated coal gasification combined cycle system according to claim 4, further comprising a converter for oxidizing SO _x from the regeneration tower, and a recovery tower for recovering the obtained SO ₃ . 8. The coal gasification according to claim 1, wherein the char discharged from the coal partial oxidation furnace is introduced into a secondary desulfurization apparatus, and the char having adsorbed SO _x is processed in the oxidation furnace. Combined power generation system. 9. An apparatus for activating a coal, further comprising an activating apparatus for introducing the activated coal into a secondary desulfurization apparatus, adsorbing SO _x and then supplying the SOx to a partial oxidation furnace. The integrated coal gasification combined cycle system according to claim 1.