WO2017086070A1 - Method for gasifying carbonaceous fuel, method for operating iron mill, and method for producing gasified gas - Google Patents

Abstract

The present invention addresses the problem of providing: a method for gasifying a carbonaceous fuel, the method allowing the carbonaceous fuel to be gasified in high yield; a method for operating an iron mill that uses the carbonaceous fuel by gasifying the same in high yield; and a method for producing gasified gas, the method allowing the gasified gas to be produced from the carbonaceous fuel in high yield. This problem is solved by supplying the carbonaceous fuel and a gasifying agent that includes H₂, CO₂, and H₂O into a fluidized bed gasifier that uses quick lime as a fluidizing medium.

Description

Method for gasifying carbonaceous fuel, method for operating steelworks and method for producing gasified gas

The present invention relates to a carbonized fuel gasification method, a steel mill operation method, and a gasification gas production method using a fluidized bed gasification furnace.

In the past, many techniques have been disclosed for gasifying carbonaceous fuels such as coal and converting them into product gas having a relatively high calorific value.

For example, Patent Document 1, an extracted portion of the product gas produced in the coal gasification furnace, by burning the extracted product gas with oxygen to convert into CO ₂ and H ₂ O, the CO ₂ and H A coal gasification facility using a mixed gas with ₂ O as a carrier gas for supplying coal to a coal gasifier is disclosed.
In the coal gasification facility of Patent Document 1, by having such a configuration, the combustion heat of the product gas is increased as compared with the case of transporting coal with N ₂ .

Patent Document 2 discloses a gasification furnace for supplying pure oxygen, in which an iron by-product gas containing CO ₂ generated from a steelmaking furnace is supplied to the gasification furnace, and char and iron production by-product generated by coal gasification are disclosed. A method is disclosed in which the generated gas is reformed and the calorific value is increased by CO generated by the reaction with CO ₂ in the raw gas.

In Patent Document 3, as a coal coke gasification device, a fluidized bed gasification furnace (reactor) containing a fluidized bed made of a mixture of coal coke particles and a fluidized medium, and sunlight is concentrated on the upper surface of the fluidized bed. And a gasification furnace having a draft pipe buried in the fluidized bed and a means for introducing water vapor into the gasification furnace from below, and the fluidized bed becomes a draft pipe by the introduced water vapor. A gasifier having a configuration of circulating and flowing inside and outside is disclosed. In Patent Document 3, quartz sand (SiO ₂ ) is mainly used as a fluid medium.
The apparatus described in Patent Document 3 uses a fluidized bed made of a mixture of coal coke particles and a fluidized medium, thereby preventing a decrease in the reaction rate of the fluidized bed particles and allowing the gasification reaction to proceed smoothly. Yes.

Further, Patent Document 4 discloses a gasification method using steam as a gasifying agent and CaO as a fluid catalyst in co-gasification of biomass and coal.
Specifically, Patent Document 4 uses a three-column circulating fluidized bed composed of a fluidized bed combustion tower, a fluidized bed tar reforming tower, and a fluidized bed gasification tower in co-gasification of biomass and coal. Using CaO as a heat medium, tar reforming catalyst, and CO ₂ and H ₂ S absorbent, circulating CaO in an apparatus connecting three towers and supplying biomass, coal, and high-temperature steam to the gasification tower Then, a method of generating gasified gas by generating volatile gas and char (fixed carbon) by gasifying the gas with steam by thermally decomposing in contact with a heat medium is disclosed. ing. Further, Patent Document 4 introduces volatile matter gas generated in a gasification tower, gasification gas, and water vapor into a tar reforming tower, performs catalytic reforming of tar in contact with a heat medium, and Char is introduced into the combustion tower together with the heat medium, the heat medium is heated by burning the char with air, and the heated heat medium is returned to the tar reforming tower and the gasification tower through the cyclone. Maintaining the temperature of the quality column and gasification column is also disclosed.
Since this method is steam gasification, the gasification reaction is considered to be mainly a steam reforming reaction of methane represented by the formula (1).
CH ₄ + H ₂ O → CO + 3H ₂ Formula (1)

JP 2000-355893 A Japanese Patent Laid-Open No. 2007-9069 Japanese Patent Laying-Open No. 2015-86232 JP 2014-74144 A

However, the above prior art has the following problems.
The facility described in Patent Document 1 extracts a part of the generated gas generated in the gasifier and burns it with oxygen to convert it into CO ₂ and H ₂ O. This mixed gas of CO ₂ and H ₂ O is converted into CO ₂ and H ₂ O. Coal carrier gas.
Therefore, the ratio of CO ₂ and H ₂ O supplied into the gasification furnace as the carrier gas cannot be arbitrarily controlled. As a result, the product gas cannot be produced in high yield by controlling the reaction amounts of the following formulas (2) and (3).
C + CO ₂ → 2CO (2)
C + H ₂ O → CO + H ₂ Formula (3)

The method described in Patent Document 2 is a method of reforming the generated gas by the above formula (2) with the CO ₂ in the iron by-product gas and the char obtained in the gasifier, and CO ₂ in the iron by-product gas. In this method, the reforming efficiency is determined depending on the concentration.
Therefore, it is the same as the equipment described in Patent Document 1 that it has a problem that the produced gas cannot be produced with high yield.

In the apparatus described in Patent Document 3, the gasification reaction can be performed using solar energy and the gasification reaction can proceed smoothly, but in terms of the yield of the product gas, it is sufficient. I can not say.
In addition, when silicon dioxide is used as the fluid medium, if a carbonaceous fuel with a high sodium content such as subbituminous coal is used as the gasification raw material, sodium and silicon dioxide react to form soda glass, soda There is also a problem that the glass is melted in the gasification furnace and cannot be smoothly gasified.

Furthermore, in the method described in Patent Document 4, since the maximum proportion of coal in the raw material is only 10%, carbonaceous fuel cannot be gasified with a high yield. Further, since CaO acts as a catalyst for the steam reforming reaction of methane represented by the above-described formula (1), in which a large amount of H ₂ is generated, CO that is a high combustion heat component in the generated gas is high. There is also a problem that it cannot be produced in a yield.

Accordingly, an object of the present invention is to provide a gasification method for carbonaceous fuel capable of gasifying carbonaceous fuel with high yield, a method for operating a steelworks using gasification of carbonaceous fuel with high yield, and carbonaceous fuel. Another object of the present invention is to provide a gasification gas production method capable of producing gasification gas with high yield.

As a result of repeated studies to solve the above-mentioned problems, the inventors of the present invention used a gasifying agent containing H ₂ , CO _2, and H ₂ O for fluidizing a carbonaceous fuel in a fluidized bed gasification furnace. While supplying to a gasification furnace, it discovered that it was effective to use quicklime (CaO) as a fluid medium. Furthermore, the present invention was completed by obtaining knowledge about a preferable production method of the gasifying agent to be used.
The present invention has been made on the basis of such findings and has the following gist.

That is, according to the gasification method for carbonaceous fuel of the present invention, when gasifying carbonaceous fuel in a fluidized bed gasification furnace, quick lime is used as a fluid medium, and a gasifying agent containing H ₂ , CO ₂ and H ₂ O is used. Is supplied to the fluidized bed gasifier, and a carbonaceous fuel gasification method is provided.

In such a method for gasifying carbonaceous fuel according to the present invention, the gasifying agent is preferably obtained by shift modification by adding excess water vapor to an iron by-product gas.
The iron by-product gas preferably has a CO concentration of 5 vol% or more and an N ₂ concentration of 60 vol% or less.
Furthermore, the carbonaceous fuel is preferably at least one selected from peat, lignite and subbituminous coal.

The first aspect of the method for operating a steel mill according to the present invention is to supply a carbonaceous fuel and a gasifying agent containing H ₂ , CO ₂ and H ₂ O to a fluidized bed gasifier using quick lime as a fluidized medium. By doing so, the operation method of the steelworks which gasifies the said carbonaceous fuel and uses the produced | generated gas as at least one part of the energy source of a steelworks is provided.

The second aspect of the operation method of the steelworks of the present invention, the fluidized-bed gasification furnace used quicklime as flow medium, and carbonaceous fuel, and the gasifying agent comprising H _2, CO ₂ and H ₂ O To provide a method for operating a steel mill that gasifies the carbonaceous fuel and uses the generated gas as at least a part of the iron oxide reducing material.

In such a method for operating a steel mill according to the present invention, the gasifying agent is preferably obtained by shift modification by adding excess water vapor to a steelmaking byproduct gas.
Further, the generated gas is preferably a mixed gas containing CO, H ₂ and a hydrocarbon having 1 to 4 carbon atoms.

Furthermore, the method for producing gasified gas of the present invention supplies a carbonaceous fuel and a gasifying agent containing H ₂ , CO _2, and H ₂ O to a fluidized bed gasifier using quick lime as a fluidized medium. Provides a method for producing gasified gas, characterized in that the carbonaceous fuel is gasified.

In such a method for producing a gasification gas according to the present invention, the gasifying agent is preferably obtained by shift modification by adding excess water vapor to an iron-produced by-product gas.

According to the gasification method for carbonaceous fuel of the present invention, the carbonaceous fuel can be gasified with a high yield, and the carbonization fuel can be gasified at low cost. Further, according to the method of operating a steel plant of the present invention, the operation cost in the steel plant is obtained by gasifying the carbonaceous fuel with a high yield and using the generated gas for the energy source of the steel plant and the reduction of iron oxide. Can be reduced. Furthermore, according to the gasification gas production method of the present invention, gasification gas can be produced with high yield by gasification of carbonaceous fuel.

FIG. 1 is a conceptual diagram for explaining an example of a carbonaceous fuel gasification method, an ironworks operation method, and a gasification gas production method of the present invention.

Hereinafter, the gasification method for carbonaceous fuel, the method for operating a steel mill and the method for producing gasification gas according to the present invention will be described in detail based on preferred examples shown in the accompanying drawings.

FIG. 1 shows a conceptual diagram for explaining an example of a carbonized fuel gasification method, an ironworks operation method, and a gasification gas production method of the present invention. In addition, the operation method of the steelworks of the present invention is that the generated gas generated by the method shown in FIG. 1 is converted into at least part of the energy in the steelworks or at least part of the reducing material in the reduction of iron oxide at the steelworks. It is used as

The present invention gasifies carbonaceous fuel such as coal.
In the example shown in FIG. 1, a gas dispersion plate 12 is provided in the fluidized bed gasification furnace 10, and quick lime (powder) is used as a fluidized medium on the gas dispersion plate 12 in the fluidized bed gasification furnace 10. Filled to form a fluidized bed 16. In the following description, “fluidized bed gasifier 10” is also referred to as “gasifier 10”.
A shift modifier 14 is provided below the gasification furnace 10. In FIG. 1, an iron-produced by-product gas and water vapor are supplied to the shift modifier 14 and the iron-produced by-product gas (shift-modified iron-produced byproduct gas) modified by the shift modifier 14 is used as a gasifying agent. By blowing this gasifying agent into the fluidized bed 16 via the gas dispersion plate 12, the gasifying agent is supplied to the gasification furnace 10, and the fluidized bed 16, that is, the quick lime as the fluidizing medium is fluidized.

A predetermined amount of carbonaceous fuel such as lignite, which is a gasification raw material, is cut out by a feeder (not shown) and is quantitatively supplied into the gasification furnace 10 continuously or intermittently from above. The carbonaceous fuel supplied to the gasification furnace 10 is gasified by the action of the gasifying agent and quicklime which is a fluidized medium. The product gas generated by the gasification of the carbonaceous fuel is discharged (recovered) from the upper part of the gasification furnace 10.

In the present invention, the gasification furnace 10 is not limited. Therefore, in addition to a general bubble fluidized bed, various known types of fluidized bed gasification furnaces such as a high-speed fluidized bed, an external circulating fluidized bed, or an internal circulating fluidized bed can be used.
The present invention uses a fluidized bed gasification furnace with fast heat transfer and uses quick lime as a fluidized medium, thereby eliminating the temperature distribution and making the reaction progress in the gasification furnace uniform. Furthermore, the carbonaceous fuel can be gasified with a high yield by fully expressing the action of quicklime as described below as a catalyst.

There is no restriction | limiting also in the shift modifier 14, The well-known reactor which can perform shift modification reaction, such as a fixed bed reactor and a fluidized bed reactor, can be used.
The shift modifier 14 is usually filled with a commercially available shift catalyst. In addition, although there exist a low temperature shift catalyst and a high temperature shift catalyst as a shift catalyst, both can be used in this invention.
In the illustrated example, the shift-modifier 14 is supplied with both the iron-produced by-product gas and water vapor with the flow rate adjusted by a known method. Moreover, you may preheat the iron-producing by-product gas, water vapor | steam, or the mixed gas of iron-manufacturing by-product gas and water vapor | steam as needed.

The shift modifier 14 is supplied with a mixed gas of iron by-product gas and excess water vapor. In addition, excess water vapor | steam means the excessive quantity with respect to CO contained in iron-making byproduct gas in Formula (4) mentioned later.
The ironmaking byproduct gas contains CO and H ₂ O. When iron-produced by-product gas and excess water vapor are supplied to the shift reformer 14, the iron-produced by-product gas is shift-modified as shown in the following formula (4), and gasification containing CO ₂ , H ₂ and H ₂ O is performed. It becomes an agent (shift-modified steelmaking byproduct gas).
CO + H ₂ O → CO ₂ + H ₂ Formula (4)
That is, the gasifying agent that has been shift-denatured by adding excess water vapor to the iron by-product gas contains CO ₂ and H ₂ resulting from shift denaturation, and H ₂ O that is an excess of water vapor added excessively.

As described above, the carbonaceous fuel that is the gasification raw material is supplied in a constant amount from the upper portion of the gasification furnace 10 continuously or intermittently.
The carbonaceous fuel supplied into the gasification furnace 10 is gasified by the action of the gasifying agent and the fluidized medium. As will be shown later in the examples, the present invention gasifies carbonaceous fuel in a high yield by using quicklime as a fluidized medium (fluidized bed 16) in the gasification of carbonaceous fuel using a fluidized bed gasification furnace. The produced gas (gasification gas) can be produced. For this reason, quick lime is presumed to have a catalytic function for the gasification reaction of carbonaceous fuel, but details are unknown.

Examples of the catalytic function of quicklime include various reforming reactions such as formulas (5) to (8) and hydrocracking reactions such as formula (9). In the present invention, since CO ₂ in the gasifying agent reacts at a high conversion rate, it is speculated that among these reactions, the contributions of the reactions of formulas (5) and (7) are large.
C + CO ₂ → 2CO (5)
C + H ₂ O → CO + H ₂ Formula (6)
CH ₄ + CO ₂ → 2CO + 2H ₂ Formula (7)
CH ₄ + H ₂ O → CO + 3H ₂ Formula (8)
C ₂ H ₆ + H ₂ → 2CH ₄ Formula (9)

In the example shown in FIG. 1, the carbonaceous fuel is shown as being supplied from the upper part of the gasification furnace 10, but the carbonaceous fuel may be supplied to the middle stage of the gasification furnace 10, or the lower stage. Alternatively, it may be supplied directly to the fluidized bed 16 region.
Further, a carrier gas such as N ₂ may be supplied to a pipe for supplying the carbonaceous fuel to the gasifier 10, and the carbonaceous fuel may be supplied to the gasifier 10 together with the carrier gas.

The product gas generated by the gasification of the carbonaceous fuel is extracted from the upper part of the gasification furnace 10 and purified through a cyclone, a gas scrubber, an oil-water separator (not shown), etc. It is taken out.
The extracted product gas can be widely used as fuel. Moreover, in the operation method of the steelworks of this invention, the produced | generated gas produced | generated in this way is used as a reducing material of the iron oxide in an energy source of a steelworks, or a steelworks.

Hereinafter, the details and preferred conditions of the carbonized fuel gasification method, the steel mill operation method, and the gasification gas production method of the present invention will be described.

In the present invention, carbonaceous fuel is gasified using a fluidized bed gasification furnace. Moreover, quicklime is used as a fluid medium.
As the quicklime (CaO), various known materials can be used. As an example, quicklime produced by calcining calcium carbonate (CaCO ₃ ), quicklime produced by firing slaked lime (Ca (OH) ₂ ), and the like can be exemplified. In addition, quick lime absorbs CO ₂ in the atmosphere and returns to CaCO ₃ , or reacts with water vapor in the atmosphere and changes to Ca (OH) ₂ , so that inert gas such as dry air or N _{2 is used.} It is better to store quicklime in it.
Quick lime not only has sufficient heat resistance corresponding to the gasification of carbonaceous fuel, but also acts as a catalyst for the gasification reaction of carbonaceous fuel as described above. Therefore, according to the present invention, a carbonaceous fuel can be gasified with a high yield to produce a product gas (gasification gas), and the produced gas produced with a high yield can be converted into the energy and oxidation of a steelworks. It can be used as an iron reducing material.

There is no restriction | limiting in the average particle diameter of quicklime, What is necessary is just to set suitably according to the magnitude | size of the gasification furnace 10, the filling amount assumed, the supply amount of a gasifying agent, etc.
Here, in the present invention, quicklime is used as a fluid medium of the (fluidized bed) gasification furnace 10. Considering this point, the average particle size of quicklime is preferably about 30 to 300 μm, more preferably about 50 to 200 μm. By setting the average particle size of quicklime to 30 to 300 μm, good fluidity can be ensured and the operation of the gasifier 10 can be performed stably.

There is no limit to the amount of quicklime filled, depending on the size of the gasifier 10, the amount of carbonaceous fuel supplied to the gasifier 10, the amount of gasifying agent supplied to the gasifier 10, etc. What is necessary is just to set suitably the supply amount which can gasify fuel appropriately.

Gasifying agent used in the gasification of carbonaceous fuels is intended to include H _2, CO ₂ and H ₂ O.
In the present invention, quick lime is used as a fluidized medium of a fluidized bed gasifier, and a gasifying agent containing H ₂ and CO ₂ in addition to H ₂ O is used to produce carbonaceous fuel in a high yield. It is possible to make it.

As described above, in Patent Document 4, in co-gasification of biomass and coal using a three-column circulating fluidized bed, a fluid medium (a heat transfer medium, a tar reforming catalyst, and CO ₂ and H ₂ S It is described that quick lime (CaO) is used as the absorbent and high-temperature steam (H ₂ O) is used as the gasifying agent.
However, in the gasification of carbonaceous fuel using quicklime as a fluid medium, when the gasifying agent does not contain H ₂ and CO ₂ but contains only H ₂ O, the above-mentioned formulas (5) and (7) Since the gasification reaction of the carbonaceous fuel by the reaction shown in FIG. 2 does not proceed, the carbonaceous fuel cannot be gasified with a high yield.

On the other hand, in the present invention, in the gasification of carbonaceous fuel, quick lime is used as a fluid medium in a fluidized bed gasification furnace, and a gasifying agent containing H ₂ and CO ₂ in addition to H ₂ O is used. As will be described later in Examples, the present invention makes it possible to cause the reaction represented by the formulas (5) and (7) to greatly contribute as described above, and to react CO ₂ at a high conversion rate. As a result, the carbonaceous fuel can be gasified with a high yield.

As described above, in the present invention, the gasifying agent used for gasification of the carbonaceous fuel contains H ₂ , CO ₂ and H ₂ O.
In the illustrated example, as a preferred embodiment, a gasification agent containing H ₂ , CO _2, and H ₂ O is used as a shift-modified iron-produced by-product gas obtained by shift modification by adding excess water vapor to the iron-produced by-product gas. It is used as.
By using a gasification agent obtained by shift-modifying iron-produced by-product gas as the gasification agent, the gasification agent becomes cheaper than a gasification agent in which pure H ₂ and CO ₂ gas is mixed with water vapor. preferable.

The iron by-product gas used as a gasifying agent by shift modification preferably has a CO concentration of 5 vol% or more and an N ₂ concentration of 60 vol% or less.
By setting the CO concentration of the iron by-product gas to 5 vol% or more, the concentrations of H ₂ and CO ₂ in the gasifying agent obtained by shift modification can be sufficiently increased, and the product gas yield can be improved. In addition, by setting the N ₂ concentration of the iron by-product gas to 60 vol% or less, it is possible to obtain sufficient combustion heat of the gaseous fuel and to improve the shift reaction rate.

Specific examples of the iron by-product gas include blast furnace gas and shaft furnace gas (general gas compositions are CO: 10 to 30 vol%, CO ₂ : 10 to 30 vol%, N from the viewpoint of the preferable gas composition described above. _{2: 30 ~ 55vol%, H} 2: 0 ~ 10vol%) is preferred.
In addition, as iron-produced by-product gas, iron-produced by-product gas containing CO other than blast furnace gas and shaft furnace gas may be used, but those having a gas composition in the above-described preferred range are preferable. Examples of such a steelmaking by-product gas include exhaust gas discharged from a combustion furnace in a steel mill and metallurgical furnace generated exhaust gas such as converter gas. The above steelmaking byproduct gas can be used alone or in combination of two or more.

In the present invention, there are no restrictions on the concentrations of H ₂ , CO ₂ and H ₂ O in the gasifying agent.
Here, the H ₂ O concentration is preferably about 5 to 70 vol% from the viewpoint of ensuring the yield of the product gas and suppressing the residual CO ₂ in the product gas. Further, from the viewpoint of ensuring the yield of the product gas, both the H ₂ concentration and the CO ₂ concentration in the gasifying agent are preferably 3 vol% or more. From the same viewpoint, the preferred composition of the gasifying agent is H ₂ O: 20 to 70 vol%, H ₂ : 5 to 40 vol%, CO ₂ : 5 to 40 vol%. Note that the gasification agent, in addition to these components, other components (e.g., N ₂₎ does not prevent be included.

The gasifying agent used in the present invention is not limited to the shift-modified iron-produced by-product gas obtained by shift modification by adding excess water vapor to the iron-produced by-product gas as described above.
That is, in the present invention, for example, the CO ₂ obtained by vaporizing H ₂ gas and liquefied gas, may be used gasifying agent was prepared by mixing the steam generated in a boiler or the like. Alternatively, a gasifying agent containing H ₂ , CO _2, and H ₂ O prepared by purifying and mixing gases produced as a by-product in an iron manufacturing process or the like may be used.

There is no limitation on the supply amount of the gasifying agent, and the gasification of the carbonaceous fuel is appropriate according to the size of the gasification furnace 10, the amount of quicklime filled in the gasification furnace 10, the supply amount of the carbonaceous fuel, etc. The amount of supply that can be performed in a short time may be set as appropriate.

As the carbonaceous fuel used as the gasification raw material, various known carbonaceous fuels such as coal, biomass, wastes such as waste tires and plastics can be used.
Among these, the carbonaceous fuel is preferably at least one selected from peat, lignite, and sub-bituminous coal. Peat, lignite, and subbituminous coal are preferably used because they are carbonaceous fuels that are relatively easily gasified, are relatively inexpensive, and are resources that exist in large quantities.

In the present invention, the carbonaceous fuel supply method is not limited, and may be dry supply or wet supply using water slurry or the like.
The size of the carbonaceous fuel is not particularly limited, but may be a standard size as a solid raw material supplied to the fluidized bed. Specifically, the size of the carbonaceous fuel is preferably 1 to 50 mm, and more preferably 3 to 30 mm. The granulation of the carbonaceous fuel may be performed by a known method.

There is no limit to the amount of carbonaceous fuel supplied. Depending on the size of the gasification furnace 10, the amount of quicklime charged in the gasification furnace 10, the amount of gasifying agent that can be supplied, etc. What is necessary is just to set suitably the supply amount which can be performed appropriately.

The gasification reaction temperature of the carbonaceous fuel is not limited, but the gasification reaction temperature is preferably 600 to 1500 ° C, more preferably 800 to 1200 ° C.
By setting the gasification reaction temperature to 600 ° C. or higher, the yield of the product gas can be improved, and by-product formation of a highly viscous tar-like substance can be prevented, thereby preventing troubles such as blockage of piping. Further, by setting the gasification reaction temperature to 1500 ° C. or less, a product gas having high combustion heat can be obtained. Furthermore, by setting the gasification reaction temperature to 1500 ° C. or less, it is preferable in that the cost can be reduced by suppressing the amount of the heat source input to the gasification furnace 10.

There is no limitation on the heating method of the gasification furnace 10, such as a method using an external heating heater, a method of supplying a heating medium to a jacket covering the gasification furnace, and heating the gasification furnace 10. What is necessary is just to perform by the well-known method utilized for heating of this.

The operation method of the steel mill of the present invention is to use the gas generated by performing the same treatment as the gasification method of the carbonaceous fuel of the present invention for the operation of the steel mill, and a fluidized bed using quick lime as a fluid medium. By supplying carbonaceous fuel and a gasifying agent containing H ₂ , CO _2, and H ₂ O to the gasifier, the carbonaceous fuel is gasified, and in the first aspect, the generated gas is made into iron. In the second embodiment, the generated gas is used as at least a part of a reducing material in the reduction of iron oxide in iron making.
Although the product gas according to the present invention has a wide range of uses as a fuel gas, it is preferable to use a shift-modified iron production by-product gas as a gasifying agent as described above, so that it is used as an energy source in a steel plant. It is reasonable. The use of the product gas according to the present invention specifically includes a fuel for private power generation facilities, a fuel gas for sintering iron ore, a fuel gas for a blast furnace hot stove, or a mix produced by mixing various by-product gases. Examples thereof include gas source gas.
The product gas according to the present invention is a gas containing CO, H ₂ and hydrocarbons having 1 to 4 carbon atoms. Therefore, this generated gas can be used as a reducing material for iron oxide to be introduced into a blast furnace, a shaft furnace, or the like. Here, the iron oxide includes dust and sludge containing iron oxide generated in a blast furnace, a converter and the like in addition to iron ore.
As will be shown later in Examples, according to the present invention, product gas can be obtained from carbonaceous fuel with high yield. Therefore, according to the operation method of the steelworks of the present invention, the cost of energy used at the steelworks and the reduction cost of the oxidizing gas can be reduced.

The gasified gas production method of the present invention is a gasified gas produced by performing the same process as the carbonaceous fuel gasification method of the present invention, and a fluidized bed gasification furnace using quick lime as a fluidized medium. In addition, a carbonized fuel and a gasifying agent containing H ₂ , CO _2, and H ₂ O are supplied to gasify the carbonaceous fuel to produce a gasified gas.
As described above, according to the present invention, product gas can be obtained from carbonaceous fuel with high yield. Therefore, according to the gasification gas production method of the present invention, the gasification gas can be produced with a high yield, and the production cost of the gasification gas can be reduced.

As mentioned above, although the gasification method of the carbonaceous fuel of this invention, the operation method of a steel mill, and the manufacturing method of gasification gas were demonstrated in detail, this invention is not limited to the above-mentioned example, The summary of this invention is shown. Of course, various improvements and modifications may be made without departing from the scope.

Hereinafter, specific examples of the present invention will be given, and the gasification method for carbonaceous fuel, the method for operating a steel mill, and the method for producing gasification gas according to the present invention will be described in more detail.
Needless to say, the present invention is not limited to the following examples.

[Example 1]
A micro fluidized bed gasification test apparatus (inner diameter: 22 mm) capable of supplying 10-30 g / h (hours) of coal by dry supply was prepared.
The gasification test apparatus was filled with a reagent CaO (manufactured by High-Purity Chemical Laboratory) as a fluid medium at 75 mm as a bed height at rest. Further, a mixed gas containing H ₂ : 14 vol%, H ₂ O: 35 vol%, CO ₂ : 24 vol%, N ₂ : 27 vol% was prepared as a simulated shift-modified iron byproduct gas and used as a gasifying agent.
This gasifying agent 400 mL (liter) / min was supplied from the lower part of the fluidized bed to fluidize CaO.
As the carbonaceous fuel, lignite (55 wt% volatile, 36 wt% fixed carbon, 8 wt% ash) granulated to a diameter of 1 to 3 mm using water as a binder (water content after granulation: 14 wt%) was used.

After the temperature inside the fluidized bed was raised to 1000 ° C. with an external heating heater, granulated lignite was supplied at a supply rate of 20 g / h to start a gasification reaction. The reaction time was 1 hour, gas sampling was performed 3 times every 20 minutes, and the generated gas was analyzed.
As a result of averaging the three gas analysis results, the carbon-based product gas yield is 61%, and the combustion heat of the product gas is 2.6 Mcal / Nm ^3. It was. Considering this result and the result of Comparative Example 1 described later, quick lime is considered to act as a good catalyst in the gasification reaction of the carbonaceous fuel. Incidentally, 67Vol% of CO ₂ was supplied as a gasifying agent, has been consumed in the reaction, such as formula (5).
As gas components in the product gas, CO, H ₂ , and hydrocarbons having 1 to 4 carbon atoms (a mixture of paraffin and olefin) were contained in a total of 80 vol%. In addition, N ₂ and CO ₂ were included as incombustible components. Since this product gas has a total concentration of CO, H ₂ , and hydrocarbons having 1 to 4 carbon atoms of 80 vol%, it is clear that there is no problem as an energy source for ironworks or a reducing material for iron oxide. .

In addition, the carbon-based product gas yield was determined as follows.
In the present invention, the carbon sources supplied to the gasification furnace (gasification test apparatus) are carbonaceous fuel (brown coal) and a gasifying agent (simulated shift-modified iron byproduct gas).
When the supply amount of carbonaceous fuel supplied to the gasification furnace is Akg / h and the carbon concentration of the carbonaceous fuel is xwt%, the supply amount β [kmol / h] of carbon to the gasification furnace by carbonaceous fuel is It can be calculated by the following formula. In the following formula, “12” is the atomic weight of carbon.
β [kmol / h] = (A / 12) × (x / 100)
Further, when the supply amount of the gasifying agent supplied to the gasification furnace is BNm ³ / h and the CO ₂ concentration of the gasifying agent is yvol%, the supply amount γ [kmol / h] can be calculated by the following equation. In the following formula, “22.4” is the volume (L) of 1 mol of gas.
γ [kmol / h] = (B / 22.4) × (y / 100)
That is, β + γ [kmol / h] is the amount of carbon supplied to the gasifier.

On the other hand, the amount of generated gas generated in the gasifier is CNm ³ / h.
As described above, the product gas includes, as a carbon compound, CO, CO ₂ , C ₁ hydrocarbon (C ₁ ), C ₂ hydrocarbon (C ₂ ), C ₃ hydrocarbon (C ₃ ) And C ₄ hydrocarbons (C ₄ ). Here, the content of CO in the product gas is Z ₁ vol%, the content of CO ₂ is Z ₂ vol%, the content of C ₁ is Z ₃ vol%, and the content of C ₂ is Z ₄ When the vol%, the C ₃ content is Z ₅ vol%, and the C ₄ content is Z ₆ vol%, the carbon amount α [kmol / h] in the product gas is represented by the following formula. In the following formula, “22.4” is the volume (L) of 1 mol of gas.
α [kmol / h] =
{C × [(Z ₁ + Z ₂ + Z ₃ + 2Z ₄ + 3Z ₅ + 4Z ₆ ) / 100]} / 22.4

Here, in this invention, carbon resulting from a gasifying agent is also contained in the product gas produced | generated with a gasifier. Accordingly, the carbon-based product gas yield [%] is calculated by the following equation by subtracting the carbon supply amount γ by the gasifying agent from the amount α of carbon in the product gas. .
Product gas yield [%] = [(α−γ) / (β + γ)] / 100

[Example 2]
A gasification test was conducted in the same manner as in Example 1 except that the carbonaceous fuel was sub-bituminous coal having a volatile content of 40 wt%, fixed carbon of 52 wt%, ash content of 9 wt%, and a moisture content of 3 wt% after granulation.
As a result, the carbon-based product gas yield was 32%, and the combustion heat of the product gas was 2.5 Mcal / Nm ³ . Although the gas yield was lower than that of lignite, a gas with high combustion heat was obtained at a relatively high yield considering that 52 wt% of fixed carbon was contained. Considering this result and the result of Comparative Example 2 described later, it is considered that quick lime acts as a good catalyst in the gasification reaction of the carbonaceous fuel as in Example 1. Incidentally, 49Vol% of CO ₂ was supplied as a gasifying agent, has been consumed in the reaction, such as formula (5).
As gas components in the product gas, CO, H ₂ and hydrocarbons having 1 to 4 carbon atoms (a mixture of paraffin and olefin) were contained in a total of 73 vol%. In addition, N ₂ and CO ₂ were included as incombustible components. Since the total concentration of CO, H ₂ , and hydrocarbons having 1 to 4 carbon atoms is 73 vol%, it is clear that this product gas has no problem as an energy source for ironworks or as a reducing material for iron oxide. is there.

[Comparative Example 1]
A gasification test was performed in the same manner as in Example 1 except that the fluid medium was industrial silica sand (SiO ₂ ).
As a result, the carbon-based product gas yield was 36%, and the combustion heat of the product gas was 2.7 Mcal / Nm ³ . Since SiO ₂ is considered to be completely inactive as a catalyst for the gasification reaction, the gas yield was very low as compared with Example 1 using quicklime as a fluid medium. The combustion heat of the product gas was almost the same as in Example 1.

[Comparative Example 2]
A gasification test was performed in the same manner as in Example 2 except that the fluid medium was industrial silica sand (SiO ₂ ).
As a result, the carbon-based product gas yield was 10%, and the combustion heat of the product gas was 2.4 Mcal / Nm ³ . As in Comparative Example 1, in this example using SiO ₂ having no catalytic activity as a fluid medium, the gas yield was much lower than that in Example 2. The combustion heat of the product gas was about the same as in Example 2.

It can be suitably used for the generation of fuel gas used in the steel industry and the power generation industry and the reduction of iron oxide at steelworks.

10 Gasifier 12 Gas Dispersion Plate 14 Shift Modifier 16 Fluidized Bed

Claims (10)

1. When gasifying a carbonaceous fuel in a fluidized bed gasification furnace, quick lime is used as a fluidized medium, and a gasifying agent containing H ₂ , CO ₂ and H ₂ O is supplied to the fluidized bed gasification furnace, To gasify carbonaceous fuel.
2. The method for gasifying a carbonaceous fuel according to claim 1, wherein the gasifying agent is obtained by shift modification by adding excess water vapor to an iron byproduct gas.
3. The steel-product gas is a CO concentration of 5 vol% or more, the gasification method of the carbonaceous fuel according to claim 2 N ₂ concentration is less 60 vol%.
4. The method for gasifying carbonaceous fuel according to any one of claims 1 to 3, wherein the carbonaceous fuel is at least one selected from peat, lignite and subbituminous coal.
5. Produced by gasifying the carbonaceous fuel by supplying carbonaceous fuel and a gasifying agent containing H ₂ , CO ₂ and H ₂ O to a fluidized bed gasifier using quick lime as a fluidized medium A method of operating a steel plant that uses gas as at least part of the energy source of the steel plant.
6. Produced by gasifying the carbonaceous fuel by supplying carbonaceous fuel and a gasifying agent containing H ₂ , CO ₂ and H ₂ O to a fluidized bed gasifier using quick lime as a fluidized medium A method of operating a steel mill that uses gas as at least part of the iron oxide reducing material.
7. The method for operating a steel mill according to claim 5 or 6, wherein the gasifying agent is obtained by shift modification by adding excess water vapor to an iron by-product gas.
8. The method of operating a steel mill according to any one of claims 5 to 7, wherein the generated gas is a mixed gas containing CO, H ₂ and a hydrocarbon having 1 to 4 carbon atoms.
9. The carbonaceous fuel is gasified by supplying carbonaceous fuel and a gasifying agent containing H ₂ , CO ₂ and H ₂ O to a fluidized bed gasification furnace using quick lime as a fluidized medium. A method for producing gasification gas.
10. The method for producing a gasification gas according to claim 9, wherein the gasifying agent is obtained by shift modification by adding excess water vapor to an iron byproduct gas.

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