JP2020084184A - Method of reducing carbon dioxide and facility for producing coke - Google Patents

Abstract

To make it possible to produce coke oven gas having a higher calorie, even if input energy is taken into consideration and subtracted.SOLUTION: A method of reducing carbon dioxide, comprising (i) a coke oven reaction process in which carbon dioxide is supplied to a carbonization chamber in a coke oven filled with coal, and the carbon dioxide is converted to carbon monoxide through reaction with carbon components and hydrogen that are present in the carbonization chamber, and (ii) a catalytic reforming step of supplying the coke oven gas containing an unreacted portion of the carbon dioxide supplied to the chamber, to a catalyst furnace charged with a catalyst, thereby reforming the unreacted carbon dioxide into carbon monoxide.SELECTED DRAWING: Figure 1

Description

The present invention relates to a carbon dioxide reduction method and a coke manufacturing facility.

The steel industry is an energy-intensive industry, and about 40% of the waste heat in the integrated blast furnace ironmaking process is unused waste heat. Among unused waste heats, as a heat source that is easily recovered but has not been used conventionally, there is sensible heat of high temperature coke oven gas (Cokes Oven Gas: COG) generated from a coke oven. Conventionally, the sensible heat of the high temperature coke oven gas is hardly used, and in most cases, the cooled gas is processed and used. On the other hand, in recent years, while the reduction of carbon dioxide emissions has become a problem, the steel industry is an industry that emits large amounts of carbon dioxide. There is.

For example, Patent Document 1 below discloses a method of supplying carbon dioxide to a carbonization chamber of a coke oven and increasing the amount of coke oven gas by utilizing sensible heat in the coke oven. According to Patent Document 1, the supplied carbon dioxide is 0.1 to 10% of the COG generation amount. In Patent Document 1, when converted to the ratio of tar and hydrocarbon in COG to carbonaceous matter (CO ₂ /C), 0.002 to 0.2 equivalent of carbon dioxide is supplied to generate carbon dioxide during the carbonization process. It is said that the Budoire reaction (CO ₂ +C→2CO) in which the high temperature powdered coke or adhered carbon and the carbon dioxide react with each other is advanced.

Similar to Patent Document 1, as a method for increasing carbon dioxide by reacting carbon dioxide in a coke oven, Patent Document 2 below discloses a method of supplying carbon dioxide and pulverized coal to the coke oven. In the cited document 2, it is said that by simultaneously supplying pulverized coal, the conversion rate of carbon dioxide by the Boudwar reaction can be increased, and the supplied carbon dioxide is heated to 500°C.

Further, in the following Patent Document 3 and Patent Document 4, in order to remove carbon adhering to the inner wall of the furnace top space of the carbonization chamber of the coke oven, it is generated in the combustion chamber of the coke oven containing CO ₂ and H ₂ O. By supplying a part of the combustion exhaust gas (3.5 or 80 Nm ³ /h · kiln; 25% of CO ₂ is 25%) to the carbonization chamber, while removing the carbon adhering to the inner wall of the furnace top space, a coke oven It is said that it can be recovered as gas.

Further, in Patent Document 5 below, carbon dioxide is used in dry quenching of coke to cool the coke by an endothermic reaction due to a Boudwar reaction, while converting carbon dioxide into carbon monoxide, and further converting the converted monoxide. It is disclosed that carbon is recovered and used for heating a carbonization chamber of a coke oven.

On the other hand, a method of reacting high temperature COG with carbon dioxide using a catalyst is disclosed by the present inventors, for example, in Patent Documents 6 to 8 below. The present inventors used a tar-containing gas reforming catalyst composed of a component obtained by mixing nickel and magnesium with various metal components such as alumina and the like as a third component, to produce a tar-containing COG or biomass gasification gas. A method of modifying is disclosed. For example, Patent Documents 6 and 7 below disclose a tar-containing gas reforming catalyst composed of an oxide containing nickel, magnesium, and aluminum. Further, Patent Document 8 below discloses a tar-containing gas reforming catalyst composed of an oxide containing nickel, magnesium, cerium, zirconium, and aluminum. In both catalysts, the main purpose is to amplify hydrogen contained in COG, and in addition to steam or carbon dioxide contained in COG, either steam or carbon dioxide is further added from the outside to reform tar. We are trying to improve the activity.

Japanese Patent Publication No. 2013-515834 JP, 2017-115125, A JP-A-3-212486 JP-A-3-212487 Japanese Patent Publication No. 2014-528503 JP, 2010-17701, A International Publication No. 2010/035430 JP, 2011-212574, A

However, in the techniques disclosed in Patent Documents 1 to 5 above, since carbon dioxide is reacted only in the coke oven, if carbon dioxide is supplied too much, unreacted carbon dioxide that is not converted into carbon monoxide remains. The amount will increase. Therefore, according to the study by the present inventors, there was a problem that COG could be supplied up to 10% at maximum. In addition, the above-mentioned Patent Document 2 does not mention the supply amount and supply range of carbon dioxide, and also whether the energy required for heating the supplied carbon dioxide (emission of carbon dioxide) is taken into consideration. , Not mentioned.

As described above, in the techniques disclosed in Patent Documents 1 to 5, the reaction rate of the supplied carbon dioxide is limited, so that a large amount of carbon dioxide cannot be supplied.

Further, regarding the techniques disclosed in Patent Documents 6 to 8 above, the tar reforming reaction is an endothermic reaction, and in order to proceed with the addition of steam or carbon dioxide from the outside, new energy is required. is necessary. Here, in the above reaction, carbon dioxide is generated along with the progress of the reaction, but in Patent Documents 6 to 8 above, the generation amount of carbon dioxide and the like are not mentioned. As a result of further studies on the reaction of COG and carbon dioxide with only the catalysts described in Patent Documents 6 to 8 above, when the energy required for the reaction was taken into consideration, the present inventors It has become clear that there is room for further improvement in the reduction of carbon dioxide emissions.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to make it possible to further increase the calorie of the coke oven gas even if the input energy is subtracted, carbon dioxide. To provide a reduction method and coke manufacturing equipment.

In order to solve the above problems, the present inventors have diligently studied a method for reducing a large amount of carbon dioxide using a coke oven and a catalyst. As a result, two new findings shown in (a) and (b) below could be obtained.

(A) By supplying carbon dioxide to the carbonization chamber of the coke oven, the tar and hydrogen generated by the carbonization of the coal in the carbonization chamber react with carbon dioxide, and the carbon dioxide is converted into carbon monoxide. At the same time, the volume of COG is amplified.
(B) By reacting high-temperature COG containing unreacted carbon dioxide immediately after it comes out of the carbonization chamber using a catalyst, tar and hydrocarbons in the COG react with carbon dioxide to carry out monoxide. Converted to carbon, the COG volume is further amplified.

The present inventors have conceived that, based on the two new findings as shown in (a) and (b) above, COG calories can be increased while improving the reaction rate of carbon dioxide. That is, by combining the reaction in the coke oven and the reaction in the catalyst, it is possible to efficiently convert carbon dioxide, including the generation of carbon dioxide by the new energy required for the reaction, and improve the calories of COG. Became clear.

COG by such a method of reducing carbon dioxide can further improve the calories of COG by subtracting both the energy required to raise carbon dioxide at room temperature to the reaction temperature and the energy required for the endothermic reaction. it can.
The gist of the present invention completed based on the above findings is as follows.

(1) Reaction in a coke oven in which carbon dioxide is supplied to a coal-filled carbonization chamber of a coke oven, and the carbon dioxide is reacted with carbon components and hydrogen existing in the carbonization chamber to convert into carbon monoxide And a coke oven gas containing unreacted carbon dioxide supplied to the carbonization chamber is supplied to a catalytic furnace provided with a catalyst to reform unreacted carbon dioxide into carbon monoxide. A method for reducing carbon dioxide, which comprises:
(2) The carbon dioxide supplied to the carbonization chamber has a molar ratio with respect to a carbon component in the coke oven gas of more than 0.2 and 2.0 or less. How to reduce.
(3) The space velocity of the coke oven gas containing the unreacted part of the carbon dioxide supplied to the catalyst furnace is 250 h ⁻¹ or more and 2000 h ⁻¹ or less, and the carbon dioxide according to (1) or (2). How to reduce carbon.
(4) In the catalyst reforming step, further supplying carbon dioxide to the catalyst furnace together with the coke oven gas containing the unreacted portion of the carbon dioxide, (1) to (3) The method for reducing carbon dioxide described.
(5) The carbon dioxide supplied to the catalytic furnace has a molar ratio with respect to a carbon component in the coke oven gas of 0.1 or more and 1.0 or less. How to reduce.
(6) The carbonization chamber is provided with a discharge port for discharging the coke produced from the coal, and a riser pipe for discharging the coke oven gas containing the unreacted carbon dioxide. Any one of (1) to (5), wherein the carbon dioxide supplied to the carbonization chamber of the coke oven is supplied into the carbonization chamber from a predetermined position closer to the discharge port than the rising pipe. The method for reducing carbon dioxide described in 1.
(7) The carbon dioxide reduction method according to (6), wherein the carbon dioxide is supplied to the furnace top space of the carbonization chamber.
(8) When the ash of the coal filled in the carbonization chamber is measured by a fluorescent X-ray analysis method, the concentration of CaO and MgO in the obtained ash composition is 3% by mass or more in total, ( The method for reducing carbon dioxide according to any one of 1) to (7).
(9) When the ash of the coal filled in the carbonization chamber is measured by a fluorescent X-ray analysis method, the concentration of Fe ₂ O ₃ in the obtained ash composition is 5% by mass or more, (1 )-(8) The method for reducing carbon dioxide according to any one of.
(10) The carbon dioxide reduction method according to any one of (1) to (9), wherein the coal filled in the carbonization chamber is allowed to contain a Ca component prior to filling.
(11) The carbon dioxide reduction method according to any one of (1) to (10), wherein after the coal is filled in the carbonization chamber, a Ca-containing material is installed on a surface layer of the filled coal.
(12) The method for reducing carbon dioxide according to any one of (1) to (11), wherein formic acid is contained in the coal filled in the carbonization chamber prior to filling.
(13) A carbonization chamber is provided in which carbon dioxide is supplied to the filled coal, and in the carbonization chamber, coke is produced from the filled coal and the carbon dioxide is present in the carbonization chamber. A coke oven that is converted into carbon monoxide by reacting with a carbon component and hydrogen that are provided, a catalyst is provided inside, and a coke oven gas containing an unreacted portion of the carbon dioxide supplied to the carbonization chamber is According to the reaction degree of the reaction inside the carbonization chamber and the catalyst furnace in which the unreacted portion of the carbon dioxide is reformed to carbon monoxide, the carbon dioxide is supplied to the carbonization chamber. A carbon dioxide supply control mechanism for controlling the supply amount of carbon dioxide, the coke manufacturing equipment.

As described above, according to the present invention, it is possible to reduce carbon dioxide at room temperature in a large amount by using the sensible heat of the coke oven and the COG, and the catalyst to further increase the calorie of the COG. In particular, even if the energy for heating the carbon dioxide at room temperature to the reaction temperature and the newly input energy required for the endothermic reaction are subtracted, COG can be further increased in calories.

It is explanatory drawing which showed typically the structure of the coke manufacturing equipment which concerns on embodiment of this invention. It is explanatory drawing which showed typically an example of the structure of the coke oven and the catalyst furnace in the coke manufacturing equipment which concerns on the same embodiment. It is a flowchart which showed an example of the flow of the reduction method of the carbon dioxide which concerns on the same embodiment. It is the graph figure which showed the net calorie of COG and its ratio in an Example. It is a graph which showed the net calorie of COG and its ratio in a comparative example.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present specification and the drawings, constituent elements having substantially the same functional configuration are designated by the same reference numerals, and a duplicate description will be omitted.

In the carbon dioxide reduction method according to the embodiment of the present invention, carbon dioxide is supplied to the carbonization chamber of the coke oven, and the tar and hydrogen generated in the carbonization of the coal and the coal filled in the carbonization chamber of the coke oven, and carbon dioxide By reacting with and, carbon dioxide is converted into carbon monoxide. Further, in the carbon dioxide reduction method according to the embodiment of the present invention, the high temperature coke oven gas (COG) containing unreacted carbon dioxide is further reformed by a catalyst, and the reaction between the hydrocarbon and carbon dioxide causes Converts carbon dioxide to carbon monoxide. Further, in the carbonization chamber of the coke oven, coke is produced from the coal in the carbonization chamber in the course of the above reaction.

(About coke manufacturing equipment)
<Overall structure of coke manufacturing equipment>
Hereinafter, first, the overall configuration of the coke manufacturing equipment used in the carbon dioxide reduction method according to the present embodiment will be described with reference to FIG. 1. FIG. 1 is an explanatory diagram schematically showing the configuration of the coke manufacturing equipment according to the present embodiment.

As schematically shown in FIG. 1, the coke manufacturing equipment 1 according to the present embodiment includes a coke oven 10 and a catalyst furnace 20 provided on the downstream side of the coke oven.

The inside of the coke oven 10 (more specifically, the inside of the carbonization chamber provided in the coke oven 10) is filled with coal. The charged coal becomes coke by being carbonized in the coke oven 10. Further, COG (hydrocarbon reforming COG) containing hydrocarbons such as methane and tar is generated during the process in which coal becomes coke. In the coke manufacturing facility 1 according to the present embodiment, by supplying carbon dioxide into the coke oven 10, COG or hydrogen is reacted with carbon dioxide to reduce carbon dioxide to carbon monoxide. Here, the supply amount of carbon dioxide supplied into the coke oven 10 is controlled by a control valve 30 as an example of a carbon dioxide supply control mechanism.

Further, in the coke manufacturing facility 1 according to the present embodiment, a catalytic furnace 20 provided with a reforming catalyst for reforming hydrocarbons is provided at a position near the downstream side of the coke oven 10. The reformed COG in the coke oven generated in the coke oven 10 is supplied to the catalyst furnace 20. The reformed COG in the coke oven contains carbon dioxide that has become unreacted inside the coke oven 10 in addition to components such as hydrocarbon and tar. By supplying such a reforming COG in the coke oven into the catalyst furnace 20, the tar and the hydrocarbon in the reforming COG in the coke oven react with carbon dioxide through the reforming catalyst, Unreacted carbon dioxide is reduced to carbon monoxide. As a result, the reduction rate of carbon dioxide supplied into the coke oven 10 can be further improved. Further, COG after the unreacted carbon dioxide is reduced to carbon monoxide is discharged to the outside of the catalytic furnace 20 as catalyst reforming COG.

Here, in the coke manufacturing equipment 1 according to the present embodiment, in order to more efficiently proceed the reduction reaction of carbon dioxide in the catalytic furnace 20, with respect to the coke internal reforming COG supplied to the catalytic furnace 20, Further, it is preferable to supply carbon dioxide. Here, the amount of carbon dioxide supplied to the reforming COG in the coke oven is preferably controlled by a control valve 40 as an example of a carbon dioxide supply control mechanism.

The states of the control valve 30 and the control valve 40 are controlled by the control device 50 having a CPU, a ROM, a RAM and the like. The control device 50 controls the control valve 30 based on a preset value so as to match the degree of progress of the reaction (that is, the reaction rate) in the coke oven 10 that is identified by performing verification in advance. Alternatively, the state of the control valve 30 may be dynamically controlled while grasping the reaction rate inside the coke oven 10. Further, the control device 50 controls the control valve based on preset values so as to match the reaction rate in the coke oven 10 and the reaction rate in the catalyst furnace 20 which are specified by performing verification in advance. The control valve 40 may be controlled, or the state of the control valve 40 may be dynamically controlled while grasping the reaction rate inside the coke oven 10 and the catalyst oven 20. The control device 50 is not particularly limited, and may be an information processing device such as various computers and servers, or may be various process computers.

The overall configuration of the coke manufacturing equipment 1 according to this embodiment has been briefly described above. Hereinafter, the configurations of the coke oven and the catalyst oven in the coke manufacturing equipment according to the present embodiment and the carbon dioxide reduction method performed in the coke oven and the catalyst oven will be described in more detail with reference to FIGS. 2 and 3. Explained.

<Regarding configuration examples of coke oven and catalytic oven>
Hereinafter, first, with reference to FIG. 2, an example of a specific configuration of the coke oven and the catalytic oven in the coke manufacturing facility 1 according to the present embodiment will be described. FIG. 2 is an explanatory diagram schematically showing an example of the configuration of a coke oven and a catalytic oven in the coke manufacturing equipment according to this embodiment.

In the coke oven 10 according to the present embodiment, the internal space of the carbonization chamber 101 is filled with coal from, for example, a plurality of coal insertion ports 103 provided in the upper part of the carbonization chamber 101. A void remains in the upper part of the carbonization chamber 101 after being filled with coal, and the void is also referred to as a furnace top space 105. Usually, in order to increase the production efficiency of coke in the coke oven 10, coal is often filled in the carbonization chamber 101 so that the furnace top space 105 is as small as possible. For example, Japanese Unexamined Patent Application Publication No. 2004-124001 discloses that the height of the carbonization chamber is usually around 6 m to 7 m, and the height at which coal is filled is a level lower by about 300 mm to 350 mm from the ceiling. There is.

The coal filled in the carbonization chamber 101 is carbonized by the heat generated in the combustion chamber (not shown) of the coke oven 10 to form coke. The produced coke is discharged from the discharge port 107 provided in the carbonization chamber 101 (more specifically, from the opening formed by opening the furnace lid 109 provided at the discharge port 107) to the outside of the furnace. It In addition, a COG (reforming COG in the coke oven) 111 containing tar and hydrocarbons generated in the process of producing coke is discharged from an ascending pipe 113 provided on the opposite side of the discharge port 107 of the carbonization chamber 101. It is discharged to the outside of the coke oven 10.

Here, in the coke manufacturing equipment 1 and the carbon dioxide reduction method according to the present embodiment, carbon dioxide is supplied to the inside of the carbonization chamber 101 of the coke oven 10. The supplied carbon dioxide reacts with tar and hydrogen generated by the carbonization of coal and the coal itself inside the carbonization chamber 101, and is reduced to carbon monoxide.

In the carbonization chamber 101 of the coke oven 10, carbon dioxide reacts with coal and adhered carbon, tar, and hydrogen generated by carbonization of coal, and the Boudwar reaction represented by the following formula 101 and carbon dioxide and tar. Of the hydrocarbon (particularly tar) represented by the following formula 103, and the reverse shift reaction represented by the following formula 105 in which carbon dioxide and hydrogen react. By these reactions, the carbon dioxide supplied into the carbonization chamber 101 is reduced to carbon monoxide.

CO ₂ +C → 2CO (Formula 101)
CO ₂ +1/nC _n H _m → 2CO+(m/2n)H ₂ (Formula 103)
CO ₂ +H ₂ →CO+H ₂ O (Equation 105)

In addition, the carbon dioxide supplied to the carbonization chamber 101 is often not all reduced to carbon monoxide, and unreacted carbon dioxide, together with the generated coke in-furnace reforming COG 111, flows from the rising pipe 113 to the furnace. It is discharged to the outside.

The amount (supply amount) of carbon dioxide supplied to the carbonization chamber 101 is controlled according to the reaction degrees (reaction rates) of the above-described three types of reactions in the carbonization chamber 101. In other words, the amount of carbon dioxide supplied to the carbonization chamber 101 is controlled according to the reaction rate in the carbonization chamber 101. In other words, the COG (coke) supplied to the catalytic furnace 20 provided in the subsequent stage is controlled. It also means that the amount of carbon dioxide supplied to the carbonization chamber 101 is controlled according to the space velocity (Space Velocity: SV) of the in-furnace reforming COG) 111.

The supply amount of carbon dioxide to the carbonization chamber 101 is more than 0.2 in terms of a molar ratio (CO ₂ /C) of hydrocarbons such as tar and methane in COG generated by carbonization of coal to carbon components. preferable. By setting the molar ratio (CO ₂ /C) to more than 0.2, it becomes possible to improve the amount of carbon dioxide to be treated and to more sufficiently obtain the effect of increasing the calories of COG. The molar ratio (CO ₂ /C) is more preferably 0.5 or more, and is 0.7 or more, from the viewpoint of increasing the reduction amount of carbon dioxide and further amplifying the calories of COG. More preferably.

On the other hand, the above molar ratio (CO ₂ /C) is preferably 2.0 or less. By setting the molar ratio (CO ₂ /C) to 2.0 or less, the energy for raising the supplied carbon dioxide to the reaction temperature and the energy for compensating the endothermic reaction are suppressed, and these energies are subtracted. Even in this case, the calorie of COG after the reaction can be increased more reliably than before the reaction. If the calorie of COG after the reaction becomes smaller than that before the reaction, it is important to increase the amount of the catalyst in the subsequent catalytic reaction step and increase the amount of the reaction, so that more cost is required. Will occur. The molar ratio (CO ₂ /C) is preferably 1.5 or less, and 1.3 or less from the viewpoint of increasing the amount of carbon dioxide reduction and further amplifying the calories of COG. Is more preferable.

Carbon dioxide also reacts with hydrogen by the reverse shift reaction as shown in the above formula 105, but since the ratio of hydrocarbon and hydrogen is almost fixed in the composition of COG, the ratio of carbon dioxide to carbon should be the above. If so determined, the ratio of carbon dioxide to hydrogen can also be roughly determined. Since COG actually contains water vapor, steam reforming of hydrocarbons is also in progress.

Here, as mentioned above, in order to improve the production efficiency of coke, coal is usually filled so that the furnace top space 105 is as small as possible. Therefore, in order to make the above-mentioned reaction proceed more reliably, the carbon dioxide supply position in the carbonization chamber 101 is set to make the contact time with the tar in the coal or COG longer (in other words, carbonization). It is preferable that the residence time in the chamber 101 be long). From this point of view, carbon dioxide is preferably supplied from the upstream side of the flow of COG, and for example, may be supplied into the carbonization chamber 101 from a predetermined position on the discharge port 107 side of the rising pipe 113. preferable.

In the extruding direction in the carbonization chamber 101 of the coke oven 10 (the direction from the rising pipe 113 to the discharge port 107 in FIG. 2, also referred to as the furnace length direction), there is a pusher side (extrusion side, side where the rising pipe 113 is located). Furnace lids 109 are provided on each of the coke sides (the discharge side and the side on which the discharge port 107 is located) to prevent coal and generated COG from leaking from the carbonization chamber 101. For example, among these furnace lids 109, a carbon dioxide supply port 115 as schematically shown in FIG. 2 is provided in the furnace lid 109 located on the side opposite to the rising pipe 113 into which the generated COG flows, and carbon dioxide is supplied. May be supplied. The carbon dioxide supply port 115 is preferably provided in one or more places on the furnace lid 109 of each carbonization chamber, and may be divided into several places in the height direction. In particular, it is more preferable to supply the carbon dioxide from a lower position of the furnace lid 109 because the retention time of carbon dioxide in the carbonization chamber 101 of the coke oven 10 becomes longer and the reaction can be performed efficiently. The carbon dioxide supply port 115 may be provided, for example, by disposing a supply nozzle in the furnace top space 105 in which COG generated in the coke furnace flows, in addition to the furnace lid.

Coal is usually carbonized in the carbonization chamber 101 at a temperature of about 1000 to 1200° C., and the furnace top space 105 is usually in a state where the temperature is in the range of about 800 to 1000° C. Since the higher the temperature is, the more easily the reduction of carbon dioxide proceeds, it is more preferable to supply carbon dioxide from the lower position of the carbonization chamber 101 also from this viewpoint.

In the coke manufacturing equipment 1 according to the present embodiment, carbonization is performed in the vicinity of the outlet side of the ascending pipe 113 of the coke oven 10 and the position before the position where the COG is subjected to gas cooling (the dry main 117 in FIG. 2). A catalytic furnace (catalytic reaction furnace) 20 provided with a hydrogen reforming catalyst is provided. By providing the catalytic furnace 20 in the vicinity of the rising pipe 113, the sensible heat of COG discharged from the coke oven 10 in the high temperature state as described above can be effectively used for the catalytic reaction.

The catalyst used in the catalytic furnace 20 is not particularly limited as long as it is a general hydrocarbon reforming catalyst, and various known hydrocarbon reforming catalysts can be used. However, it is preferable to use a sulfur poisoning-resistant hydrocarbon reforming catalyst that is resistant to a high concentration of 0.2 to 0.3% by volume of hydrogen sulfide contained in COG. Examples of such sulfur poisoning-resistant hydrocarbon reforming catalysts include the catalysts disclosed in Patent Documents 4 to 6 above. The shape and reaction form of the catalyst are not particularly limited. However, the tar in the reformed COG 111 in the coke oven is likely to be thermally decomposed to cause carbon precipitation. Therefore, in the case of the fixed bed type, it is preferable to form pellets, tablets, rings, honeycombs or the like rather than the powder shape. Further, in the case of the fluidized bed type, it is preferable to use a powder catalyst pulverized to have an average particle size of 150 μm or less.

In addition, in the catalytic furnace 20, in addition to the reaction of hydrocarbons such as tar and methane with carbon dioxide in the dry reforming of hydrocarbons shown in the above formula 103, in addition to the monoxide as shown in the following formula 107, The shift reaction in which carbon and steam react mainly proceeds.

CO+H ₂ O → CO ₂ +H ₂ (Formula 107)

In order to more reliably reduce the carbon dioxide contained in the reformed COG 111 in the coke oven to carbon monoxide, it is preferable to suppress the progress of the shift reaction represented by the above formula 107. For that purpose, the amount of steam in the coke oven reforming COG 111 generated in the coke oven 10 may be reduced. Therefore, it is preferable to fill the carbonization chamber 101 of the coke oven 10 with coal previously dried by CMC (Coal Moisture Control) or DAPS (Dry-cleaned and Agglomerated Precompaction System).

In the present embodiment, the reaction temperature in the catalytic furnace 20 is preferably 650°C or higher. By setting the reaction temperature to 650° C. or higher, it becomes possible to more efficiently reduce carbon dioxide while maintaining the reforming activity of the catalyst. The reaction temperature in the catalytic furnace 20 is more preferably 700° C. or higher. On the other hand, the reaction temperature in the catalytic furnace 20 is preferably 850° C. or lower. By setting the reaction temperature to 850° C. or less, it is possible to more reliably suppress an excess of energy required for heating, and it is possible to more reliably prevent further generation of carbon dioxide. The reaction temperature in the catalytic furnace 20 is more preferably 800° C. or lower. It is more preferable to utilize the sensible heat of the reformed COG 111 in the coke oven at about 800° C. to compensate for the energy of the endothermic reaction as much as possible, as it does not lead to the generation of extra carbon dioxide.

The space velocity SV in the catalytic reaction step is preferably 250 h ⁻¹ or more. By setting the space velocity SV to 250 h ⁻¹ or more, it is possible to more reliably prevent an increase in equipment cost due to an increase in equipment size. The space velocity SV is more preferably 500 h ⁻¹ or more. On the other hand, the space velocity SV in the catalytic reaction step is preferably 2000 h ^-1 or less. In the tar reforming reaction, tar is easily decomposed to cause carbon deposition, and carbon deposition tends to be more remarkable as the space velocity SV is larger. However, by setting the space velocity SV to 2000 h ^-1 or less, it becomes possible to proceed the tar reforming reaction while more reliably suppressing such carbon precipitation. The space velocity SV is more preferably 1000 h ^-1 or less. The space velocity SV can be calculated by the gas flow rate (Nm ³ /h)/catalyst volume (m ³ ).

In the carbon dioxide reduction treatment in the carbonization chamber 101 of the coke oven 10, a part of the carbon dioxide supplied to the carbonization chamber 101 and a part of the generated hydrocarbons in the coke oven reforming COG 111 react. Therefore, when supplying carbon dioxide into the carbonization chamber 101 of the coke oven 10 at a molar ratio _(CO 2 /C)=0.5, in a coke oven reforming COG111 before catalysis, the molar ratio _(CO 2 / C )=0.3. The molar ratio _(in the case of supplying carbon dioxide to the carbonization chamber 101 of the coke oven 10 with CO 2 /C)=1.0, in a coke oven reforming COG111 before catalysis, the molar ratio _(CO 2 / C) Change to about 0.5.

In order to further increase the throughput of carbon dioxide in the catalytic furnace 20, it is preferable to additionally supply carbon dioxide before the catalyst, as shown in FIGS. 1 and 2. The amount of carbon dioxide additionally supplied before the catalyst is a molar ratio (CO ₂ /C) with respect to the carbon components of hydrocarbons such as tar and methane in the coke-furnace reforming COG111 generated by dry distillation of coal. It is preferably 0.1 or more. By setting the molar ratio (CO ₂ /C) of carbon dioxide to be additionally supplied to 0.1 or more, it becomes possible to more reliably increase the amount of carbon dioxide to be processed in the catalytic furnace 20. The amount of carbon dioxide to be additionally supplied is more preferably 0.2 or more in terms of molar ratio (CO ₂ /C).

Further, the amount of carbon dioxide to be additionally supplied before the catalyst is set to a molar ratio (CO ₂ /C) with respect to carbon components of hydrocarbons such as tar and methane in the reformed COG 111 in the coke furnace generated by carbonization of coal. ) Is preferably 1.0 or less. By setting the molar ratio (CO ₂ /C) of carbon dioxide to be additionally supplied to 1.0 or less, it is possible to more reliably ensure that both the energy required to raise the carbon dioxide and the energy that compensates for the endothermic reaction become excessive. The amount of unreacted carbon dioxide after the catalytic reaction can be suppressed more reliably. As a result, reduction of carbon dioxide emissions from the process and COG calorie amplification can be realized more reliably. The amount of carbon dioxide to be additionally supplied is more preferably 0.7 or less in terms of molar ratio (CO ₂ /C).

In the catalytic furnace 20 according to the present embodiment, as described above, the unreacted carbon dioxide contained in the coke oven reforming COG 111 is reduced to carbon monoxide by the catalytic reaction. As a result, in the coke manufacturing facility 1 according to the present embodiment, it is possible to reduce carbon dioxide at room temperature in a large amount by utilizing the sensible heat of the coke oven and the COG and the catalyst to further increase the calorie of the COG. Becomes In particular, even if the energy for heating the carbon dioxide at room temperature to the reaction temperature and the newly input energy required for the endothermic reaction are subtracted, COG can be further increased in calories.

At first glance, in order to reduce carbon dioxide in a larger amount, it may be possible to increase the amount of carbon dioxide supplied into the carbonization chamber of the coke oven without providing a catalyst furnace. However, as mentioned earlier, since the top space in the carbonization chamber of a coke oven is usually small, when a large amount of carbon dioxide is supplied to the carbonization chamber of the coke oven, the residence time of carbon dioxide in the carbonization chamber is reduced. Is not sufficiently taken, carbon dioxide does not sufficiently react in the carbonization chamber, and the calorie of COG is reduced. Therefore, in the coke manufacturing equipment 1 according to the present embodiment, the catalytic furnace 20 is provided in the latter stage of the coke oven 10 to efficiently reduce unreacted carbon dioxide, and thus the carbon dioxide supplied to the carbonization chamber 101 of the coke oven 10 is supplied. The amount of reaction of carbon is increased synergistically. Further, by providing the catalytic furnace 20, the volume of COG generated is greatly increased, so that it is possible to increase the calorie of COG.

In this way, the carbon dioxide contained in the coke oven reforming COG 111 is efficiently reduced to carbon monoxide, and the catalyst reforming COG 119 in which the carbon dioxide content is reduced is provided outside the catalyst furnace 20. Is discharged. The discharged catalyst reforming COG 119 is recovered by the dry main 117 and is cooled, for example, by spraying ammonia water.

[About molar ratio (CO ₂ /C)]
Here, the molar amount of carbon components of hydrocarbons such as tar and methane in COG generated by dry distillation of coal can be specified as follows. First, before supplying carbon dioxide, COG (reformed COG in the coke oven) generated from the carbonization chamber 101 of the coke oven 10 is sampled, and the gas composition of the COG is analyzed using gas chromatography. .. At the same time, the tar weight obtained by evaporating and removing the solvent used for collecting was collected with the tar in COG collected by the collecting method according to JIS Z 8808 (a method for measuring the dust concentration in exhaust gas), and the liquid was collected. -Analyze by gravimetric method. Further, carbon, hydrogen, etc. in the collected tar are quantitatively analyzed by JIS M 8819 (coal and coke-elemental analysis method by instrumental analyzer). By this method, the tar concentration contained in the COG discharged from the carbonization chamber 101 of the coke oven 10 is measured. This makes it possible to specify the molar amount of carbon components of hydrocarbons such as tar and methane in COG generated by dry distillation of coal. Then, by controlling the molar amount of carbon dioxide supplied to the carbonization chamber 101 of the coke oven 10 or the catalytic furnace 20, the value of the above molar ratio (CO ₂ /C) is controlled to a desired value. be able to.

Also, when the value of the molar ratio (CO ₂ /C) is subsequently measured, the molar amount of the carbon component and the molar amount of the supplied carbon dioxide should be measured separately in the same manner as above. Thus, it is possible to specify the value of the realized molar ratio (CO ₂ /C).

[About various measurement methods]
For each calorie of COG, reforming COG in the coke oven, and catalytic reforming COG, the gas collected in each process is analyzed by gas chromatography to grasp the gas concentration, and combustible gases (H ₂ , CH ₄ , CO ) And the gas flow rate (Nm ³ /h) in each step, the gas calorie (MJ/h) in each step can be calculated. The gas flow rate can be easily measured by, for example, a Pitot tube-type current meter. More accurately, the gas density (kg/Nm ³ ) in the standard state is calculated from the gas composition and the water content measured according to JIS Z 8808, and the high temperature is measured using the gas temperature measured by a K-type thermocouple or the like. It is converted to the gas density (kg/m ³ ) in the state. Subsequently, the flow velocity (m/s) was obtained from the dynamic pressure and static pressure of the flowing gas using a Pitot tube and a slight differential pressure manostar gauge, and the flow rate (Nm ³ ) of the gas was calculated together with the cross-sectional area (m ² ) of the pipe. /H) can be obtained.

On the other hand, the energy to raise the carbon dioxide at room temperature to the reaction temperature is the CO ₂ flow rate (Nm ³ /h) at room temperature to be supplied and the high temperature COG before mixing CO ₂ and coke oven The flow rate (Nm ³ /h) of the ^high- quality COG and the lowering temperature when they are mixed with each other are calculated, and the energy for raising the reaction temperature can be obtained from the obtained calculation result. The energy required for the endothermic reaction is the reaction between the COG after the carbon dioxide is supplied to the reaction temperature or the gas composition of the reformed COG in the coke oven or the reformed COG in the coke oven after the carbon dioxide is supplied. The reaction heat (endotherm) can be estimated by the Kirchhoff's law from the changed gas composition, and the endotherm can be obtained as energy for raising the reaction temperature.

The calorie of COG before supplying carbon dioxide is E ₀ , the calorie of reformed COG in the coke oven is E _CO , the calorie of the catalytically reformed COG is E _CAT , and the carbon dioxide at room temperature in the reaction process in the coke oven is raised to the reaction temperature. The energy is e ₁ , the energy required for the endothermic reaction is e ₂ , the energy for raising carbon dioxide to the reaction temperature in the catalyst reforming step is e ₃ , and the energy required for the endothermic reaction is e ₄ . The net calorie E _CO ^NET in the coke oven reaction step can be expressed as E _CO ^NET =E _CO −(e ₁ +e ₂ ), and the net calorie E _CAT ^NET in the catalyst reforming step is E _CAT ^NET = It can be expressed as E _CAT −(e ₃ +e ₄ ). Furthermore, the calorie ratio before and after the reaction in the reaction process in the coke oven can be calculated by E _CO ^NET /E ₁ , and the calorie ratio before and after the reaction including the catalyst reforming process can be calculated by E _CAT ^NET /E ₁ . can do. The calorie ratio (E _CAT ^NET /E ₁ ) in the present invention is preferably more than 1.1, more preferably 1.2 or more. Further, the higher the calorie ratio, the more it can be used as an energy source for various purposes, so there is no particular limitation on the upper limit.

Heretofore, with reference to FIG. 2, an example of a specific configuration of the coke oven and the catalyst furnace in the coke manufacturing equipment 1 according to the present embodiment has been described in detail.

<About carbon dioxide reduction method>
Next, the flow of the carbon dioxide reduction method using the coke manufacturing equipment 1 as shown in FIGS. 1 and 2 will be briefly described with reference to FIG. FIG. 3 is a flow chart showing an example of the flow of the carbon dioxide reduction method according to the present embodiment.

As shown in FIG. 3, the method for reducing carbon dioxide carried out in the coke production facility 1 as described above is performed in the coke oven reaction step (step S101) in the coke oven 10 and the catalyst reforming in the catalyst furnace 20. The process (step S103) is included.

In the coke oven reaction step (step S101), carbon dioxide is supplied to the coal-filled carbonization chamber 101 of the coke oven 10, and the carbon dioxide is reacted with carbon components and hydrogen existing in the carbonization chamber 101. This is a step of converting to carbon monoxide.

In the catalyst reforming step (step S103), a COG (reforming COG in the coke oven) 111 containing unreacted carbon dioxide supplied to the carbonization chamber 101 of the coke oven 10 is provided in a catalyst furnace provided with a catalyst. In this step, the carbon dioxide contained in the reformed COG 111 in the coke oven is reformed into carbon monoxide.

Here, since the details of the reaction process in the coke oven and the catalyst reforming process are the same as those described above, detailed description will be omitted below.

The flow of the carbon dioxide reduction method using the coke manufacturing equipment 1 as shown in FIGS. 1 and 2 has been briefly described above with reference to FIG.

<About coal used>
Next, the coal filled in the carbonization chamber 101 of the coke oven 10 will be briefly described.
Although any method can be used for analyzing the ash composition of the coal filled in the carbonization chamber 101 of the coke oven 10, the accuracy required for carrying out the coke manufacturing facility 1 and the carbon dioxide reduction method according to the present embodiment. It is convenient to use fluorescent X-ray analysis for the analysis. Normally, for light elements up to the second cycle of the periodic table (excluding hydrogen, helium, nitrogen, and oxygen), accurate component analysis is difficult by fluorescent X-ray analysis, but the ash composition in coal is Since no light elements are included, there is no problem. Note that similar results can be obtained within the measurement error range by using ICP emission analysis. Regardless of which measuring method is used, the valence and the state of existence of each element cannot be determined. Therefore, the mass ratio of each element converted to oxide is treated as the composition of each coal.

The coal can be mined from coal mines around the world. Before the coal is charged into the carbonization chamber 101 of the coke oven 10, as mentioned above, it is preferable that the coal to be used is dried by CMC or DAPS.

In the ash composition analysis of any coal, CaO and MgO are detected among the alkaline earth metals. Since these two components have high carbon dioxide adsorption ability, the reactivity of carbon dioxide can be further improved.

In the ash composition of the coal charged in the coke oven, the concentration of CaO and MgO (converted value to CaO and MgO) in the ash composition when analyzed by fluorescent X-ray measurement is 3% by mass or more in total. preferable. When the total concentration of CaO and MgO is 3% by mass or more, the reactivity of carbon dioxide can be further improved. In order to further improve the reactivity of carbon dioxide, the total concentration of CaO and MgO in the ash composition when analyzed by fluorescent X-ray measurement is more preferably 6% by mass or more in total.

Oxides of Ca and Mg, which are an example of Ca and Mg components, may be originally contained in the coal used, or may be premixed before being filled in the carbonization chamber 101 of the coke oven 10. good. When pre-mixing, compounds such as oxides, hydroxides, and carbonates may be made into powder or slurry and mixed with coal.

As the above-mentioned Ca component and Mg component, for example, various Ca-containing substances such as CaO, Ca(OH) ₂ and CaCO ₃ , and various Mg-containing substances such as MgO, Mg(OH) ₂ and MgCO _3. The thing etc. can be mentioned.

The Ca-containing material as described above may be installed, placed and concentrated on the coal filled in the carbonization chamber 101, and the Ca-containing material may be additionally filled on the coal layer after filling. Alternatively, the slurry may be sprayed onto the filled coal. By doing so, the carbon dioxide introduced into the carbonization chamber 101 and COG or tar are likely to react directly with each other, which is preferable. The amount of the Ca-containing material additionally filled is not particularly limited. However, from the viewpoint of ensuring the flowability of the generated COG and the carbon dioxide introduced into the carbonization chamber 101 in the furnace top space 105 and ensuring the quality of the coke, the height of the Ca-containing filling layer is 5 to 150 mm. It is preferable that

The Ca-containing material is preferably a compound containing Ca as a main component, and particularly preferably, CaO, Ca(OH) ₂ , CaCO _{3 and the} like can be mentioned. At the temperature in the carbonization chamber 101, Ca(OH) ₂ and CaCO ₃ can decompose and change to CaO. On the other hand, the presence of water vapor and carbon dioxide in the coexisting gas causes the reactions shown in the following formulas 109 and 111 to proceed, so that Ca is changed into various compounds during the carbonization. it is conceivable that.

CaO+H ₂ O → Ca(OH) ₂ (Formula 109)
CaO+CO ₂ → CaCO ₃ ... (Formula 111)

Further, in the ash composition analysis of the coal filled in the carbonization chamber 101 of the coke oven 10, the concentration of Fe ₂ O ₃ in the ash composition when analyzed by fluorescent X-ray measurement is preferably 5 mass% or more. Fe ₂ O ₃ may be originally contained in the coal used, or may be premixed before being charged into the carbonization chamber 101 of the coke oven 10. The premixed iron source may be iron ore. However, in a general chamber furnace coke oven, at a carbonization temperature of 1150° C. or higher, silica, which is the main component of the silica stone brick used, reacts with iron to produce low-melting firelite, and May cause damage. Therefore, it is more preferable to set the concentration of Fe ₂ O ₃ to 50% by mass or less in the ash composition analysis or to suppress the carbonization temperature to about 1100° C.

Further, it is preferable to add formic acid to the coal before filling the coal in the carbonization chamber 101 of the coke oven 10. When formic acid is added, formic acid is decomposed into carbon dioxide and hydrogen when coal is carbonized in the carbonization chamber 101. Carbon dioxide can contribute to the increase in calories of COG by reacting and being reduced to carbon monoxide. Moreover, since the reverse shift reaction of the above formula 105 is more likely to proceed due to the increase in hydrogen, the reduction efficiency of carbon dioxide can be further improved.

The amount of formic acid added is not particularly limited and may be any amount. For example, when the amount of coal to be filled in one kiln of the carbonization chamber 101 is about 30 tons, about 27.6 tons of coal that has been previously dried with DAPS to have a water content of 10% by mass to 2% by mass is used. .4t may be added (that is, the same amount of formic acid as the water removed by drying may be added). In this case, carbon dioxide generated by decomposition of formic acid is 2.3 t-CO _2, which is a molar ratio (CO ₂ /CO _{2 to} carbon of hydrocarbons such as tar and methane in COG generated by dry distillation of coal. Corresponds to C)=0.18 carbon dioxide.

If the formic acid to be used is anhydrous, it can be efficiently added to pre-dried coal. In Japan, if the content of formic acid in the aqueous solution is less than 90%, it does not correspond to the deleterious substance specified in the Poisonous and Deleterious Substances Control Law. Furthermore, if the concentration of formic acid in the aqueous solution is less than 78%, it does not correspond to a dangerous substance specified by the Fire Service Law. Therefore, change the concentration of the formic acid aqueous solution according to the situation of the factory to be used. Is also possible. However, if the concentration of formic acid in the aqueous solution is too low, the amount of water will be too large, and the water will be added again to the coal dried in advance, resulting in a waste of energy.

It is preferable that the amount of formic acid added is about 30 tons of coal and formic acid to be filled in the carbonization chamber 101, because coke productivity is not impaired. In the case of formic anhydride, it is preferable to set coal:formic acid=30t:0t to 25t:5t. Since the decomposition of formic acid is an exothermic reaction, the larger the amount of formic acid, the more the heat generated during decomposition can be used for carbonization of coal and reduction of carbon dioxide.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the conditions in the Examples are one condition example adopted to confirm the feasibility and effects of the present invention. It is not limited to the example. The present invention can employ various conditions as long as the object of the present invention is achieved without departing from the gist of the present invention.

(Example 1)
Carbon dioxide was reduced and the calorie of COG was increased using the manufacturing equipment which combined the coke oven and the catalyst oven as shown in FIG. 1 and FIG. About 30 tons of coal was filled in the carbonization chamber of the coke oven, and heated at about 1100° C. from the combustion chambers on both sides of the carbonization chamber to start dry distillation. When the ash composition analysis in coal was performed, the concentrations of CaO and MgO were 7.2% by mass and 3.1% by mass, respectively, and the Fe ₂ O ₃ concentration was 8.5% by mass with respect to the alkaline earth metal. there were. COG was generated in an amount of about 436 Nm ³ /h by dry distillation, the gas composition (volume %) was about 50% H ₂ , about 30% CH ₄ , and the balance was N ₂ . In addition, tar was generated at 136 kg/h. The gas calorie at this time was 7024 MJ/h on a dry basis.

Control for supplying carbon dioxide to carbon contained in CH ₄ and tar from the furnace lid on the outlet side at 158 Nm ³ /h so that the molar ratio (CO ₂ /C) is 0.5. I went. At this time, the temperature of the top space of the coke oven was about 950°C. Further, high-temperature coke oven reforming COG containing unreacted carbon dioxide discharged from the coke oven was supplied to a catalyst furnace heated to about 800° C., and space velocity (SV)=500 h ⁻¹ , normally. The CO ₂ reforming reaction of hydrocarbons was carried out under pressure. The gas before and after the reaction was sampled, the gas composition was analyzed by gas chromatography, and the CO ₂ conversion rate was calculated by the following formula 201.

CO ₂ conversion rate (%)=(CO ₂ volume before reaction−CO ₂ volume after reaction)/(CO ₂ volume before reaction)×100 (Formula 201)

Further, the ratio of the calorie of COG after the reaction and the calorie before and after the reaction was calculated from the gas composition and the gas volume after the reaction. The conversion rate of CO _{2 in} the coke oven is 40%, and the composition (volume %) of the reformed COG in the coke oven at the outlet of the coke oven is H ₂ 31%, CH ₄ 19%, CO 21%, CO ₂ 16%, the balance was N ₂ , and the volume was 1.54 times the COG before the reaction.

Further, in the catalytic furnace, the CO ₂ conversion rate is 50%, and the composition (volume %) of the catalytic reforming COG at the catalytic furnace outlet is H ₂ 34%, CH ₄ 15%, CO 33%, CO ₂ 7%, The balance was N ₂ , and the volume was 1.73 times that of COG before the reaction.

As a result, the calorie of COG after the reaction was 9953 MJ/h on a dry basis. Here, the energy for heating room temperature CO ₂ to the coke oven top space temperature of 950° C. and the total amount of energy required for compensating the endothermic reaction in the coke oven and the catalytic oven were calculated to be 1481 MJ/h. became. Therefore, it was found that the net calorie of COG after the reaction was 8472 MJ/h, which was 1.21 times that of the COG before the reaction. From these results, it was found that the calorie of COG can be increased by combining the coke oven and the catalyst oven and setting the molar ratio (CO ₂ /C)=0.5.

(Example 2)
Conducted in Example 1, with respect to the carbon contained of CO ₂ to CH ₄ and tar, such that the molar ratio _(CO 2 /C)=1.0, the control supplied from the furnace lid 316 nm ³ / h Example 1 was repeated except that

The CO ₂ conversion rate in the coke oven is 40%, and the gas composition of the reformed COG in the coke oven at the coke oven outlet is H ₂ 25%, CH ₄ 15%, CO 24%, CO ₂ 26%, The rest was N ₂ , and the volume was 1.98 times that of COG before the reaction. Further, the CO ₂ conversion rate in the catalytic furnace was 50%, and the composition of the catalytic reforming COG at the catalytic furnace outlet was H ₂ 26%, CH ₄ 12%, CO 43%, CO ₂ 11%, and the balance N ₂ . Yes, the volume was 2.31 times that of COG before the reaction. As a result, the calorie of COG after the reaction was 12416 MJ/h on a dry basis. Here, the total amount of energy required to heat the room temperature CO ₂ to the coke oven top space temperature of 950° C. and the energy required to compensate the endothermic reaction in the coke oven and the catalytic oven was 2260 MJ/ It became h. Therefore, it was found that the net calorie of COG after the reaction was 10156 MJ/h, which was 1.45 times that of the COG before the reaction. As described above, it was found that the calories of COG can be increased by combining the coke oven and the catalyst oven and setting the molar ratio (CO ₂ /C)=1.

(Example 3)
Conducted in Example 1, with respect to the carbon contained of CO ₂ to CH ₄ and tar, such that the molar ratio _(CO 2 /C)=1.5, the control supplied from the furnace lid 474 nm ³ / h Example 1 was repeated except that

The conversion rate of CO _{2 in} the coke oven was 25%, and the composition of the reformed COG in the coke oven at the outlet of the coke oven was as follows: H ₂ 20%, CH ₄ 12%, CO 18.5%, CO ₂ 40.9 %, the balance was N ₂ , and the volume was 2.33 times the COG before the reaction. Further, in the catalytic furnace, the CO ₂ conversion rate is 50%, and the composition of the catalytic reforming COG at the catalytic furnace outlet is H ₂ 21.2%, CH ₄ 8.5%, CO 42.4%, CO ₂ It was 20.3% and the balance was N ₂ , and the volume was 2.6 times that of COG before the reaction. As a result, the calorie of COG after the reaction was 12076 MJ/h on a dry basis. Here, the total amount of energy required to heat the room temperature CO ₂ to the coke oven top space temperature of 950° C. and the energy required to compensate the endothermic reaction in the coke oven and the catalytic oven was calculated to be 3036 MJ/ It became h. Therefore, the net calorie of COG after the reaction was 9040 MJ/h, which was 1.29 times that of the COG before the reaction. As described above, it was found that the calorie of COG can be increased by combining the coke oven and the catalyst oven and setting the molar ratio (CO ₂ /C)=1.5.

(Example 4)
Conducted in Example 1, with respect to the carbon contained of CO ₂ to CH ₄ and tar, such that the molar ratio _(CO 2 /C)=2.0, the control supplied from the furnace lid 632 nm ³ / h Example 1 was repeated except that

The conversion rate of CO _{2 in} the coke oven is 10%, and the composition of the reformed COG in the coke oven at the coke oven outlet is H ₂ 18%, CH ₄ 11%, CO 10%, CO ₂ 54%, and the balance. N ₂ and the volume was 2.68 times that of COG before the reaction. Further, in the catalytic furnace, the CO ₂ conversion rate is 50%, and the composition of the catalytic reforming COG at the catalytic furnace outlet is H ₂ 19%, CH ₄ 7%, CO 42%, CO ₂ 26%, balance N ₂ And the volume was 2.82 times that of COG before the reaction. As a result, the calorie of COG after the reaction was 12076 MJ/h on a dry basis. Here, the energy for heating room temperature CO ₂ to the coke oven top space temperature of 950° C. and the total amount of energy required for compensating the endothermic reaction in the coke oven and the catalytic oven were calculated to be 3815 MJ/ It became h. Therefore, it was found that the net calorie of COG after the reaction was 8261 MJ/h, which was 1.18 times that of the COG before the reaction. As described above, it was found that the calorie of COG can be increased by combining the coke oven and the catalyst oven and setting the molar ratio (CO ₂ /C)=2.0.

(Example 5)
Example 1 was carried out in the same manner as in Example 1 except that the catalyst amount in the catalytic reaction step was halved and the space velocity SV in the catalytic furnace was set to 1000 h ⁻¹ .

As a result, as in the case of the space velocity SV=500 h ⁻¹ in Example 1, the CO ₂ conversion rate in the catalytic furnace was 50%, and the composition of the catalytic reforming COG at the catalytic furnace outlet was H ₂ 33. %, CH ₄ 15%, CO 32%, CO ₂ 8%, balance N ₂ , and the volume was 1.72 times that of COG before the reaction. It was also found that the net calorie of COG after the reaction was 8231 MJ/h, which was 1.17 times that of the COG before the reaction. Since the reactivity does not change even if the space velocity SV is set to 1000 h ^-1 , the equipment can be made compact and the equipment cost is reduced.

(Comparative Example 1)
It carried out like Example 1 except having used only the coke oven as shown in Drawing 2, and using the manufacturing equipment which does not have a catalyst furnace.

As a result, the calorie of COG after the reaction was 8624 MJ/h on a dry basis. Here, the total amount of energy for heating CO ₂ at room temperature to the coke oven top space temperature of 950° C. and the total amount of energy required for compensating the endothermic reaction in the coke oven was 780 MJ/h. Therefore, it was found that the net calorie of COG after the reaction was 7844 MJ/h, which was 1.12 times that of the COG before the reaction. From these results, even if carbon dioxide is supplied to the coke oven at a molar ratio (CO ₂ /C)=0.5 in a production facility that does not have a catalyst furnace and that includes only a coke oven, COG It turns out that I can hardly increase the calories of.

(Comparative example 2)
In Example 1, CO ₂ was not supplied from the furnace lid of the coke oven, and as shown in FIG. 2, the carbon dioxide had a molar ratio (CO ₂ /C)=0.5 only before the catalytic furnace. It carried out like Example 1 except having controlled to supply with 158 Nm< ³ >/h.

As a result, the CO ₂ conversion rate in the catalytic furnace was 50%, and the composition of the catalytic reforming COG at the catalytic furnace outlet was H ₂ 35.5%, CH ₄ 14.1%, CO 26.6%, CO ₂ It was 12.0% and the balance was N ₂ , and the volume was 1.69 times that of COG before the reaction. As a result, the calorie of COG after the reaction was 8365 MJ/h on a dry basis. Here, the total amount of energy required to heat the room temperature CO ₂ to the catalyst furnace temperature of 800° C. and the energy required to compensate the endothermic reaction in the catalyst furnace was calculated to be 835 MJ/h. Therefore, it was found that the net calorie of COG after the reaction was 7530 MJ/h, which was 1.07 times that of the COG before the reaction. From these results, it was found that the COG calories could hardly be increased only by supplying carbon dioxide to the catalytic furnace only under the condition of the molar ratio (CO ₂ /C)=0.5.

(Comparative example 3)
Comparative Example 2 was performed in the same manner as Comparative Example 2 except that the carbon dioxide was controlled to be supplied at 316 Nm ³ /h from the front of the catalytic furnace so that the molar ratio (CO ₂ /C) was 1. ..

As a result, the CO ₂ conversion rate in the catalytic furnace becomes 50%, and the composition of the catalytic reforming COG at the catalytic furnace outlet is H ₂ 25.0%, CH ₄ 13.8%, CO 33.4%, CO ₂ It was 18.5%, the balance was N ₂ , and the volume was 1.68 times that of COG before the reaction. As a result, the calorie of COG after the reaction was 8664 MJ/h on a dry basis. The total amount of energy required to heat the room temperature CO ₂ to the catalyst furnace temperature of 800° C. and the energy required to compensate the endothermic reaction in the catalyst furnace was calculated to be 1669 MJ/h. Therefore, it was found that the net calorie of COG after the reaction was 6995 MJ/h, which was 1.00 times the COG before the reaction. From these results, it was found that the COG calorie cannot be increased only by supplying carbon dioxide only to the catalytic furnace under the condition of the molar ratio (CO ₂ /C)=1.

(Example 6)
In the same manner as in Example 1, except that the control of supplying carbon dioxide of 158 Nm ³ /h corresponding to the molar ratio (CO ₂ /C)=0.5 was further performed from before the catalytic furnace. Carried out.

As a result, the CO ₂ conversion in the catalytic furnace becomes 50%, and the composition of the catalytic reforming COG at the catalytic furnace outlet is H ₂ 23.9%, CH ₄ 9.7%, CO 45.1%, CO ₂ It was 13.0% and the balance was N ₂ , and the volume was 2.43 times the COG before the reaction. As a result, the calorie of COG after the reaction was 12424 MJ/h on a dry basis. Here, each of the energy for heating CO ₂ at room temperature to the coke oven top space temperature of 950° C. and the catalyst oven temperature of 800° C., and the energy required to compensate the endothermic reaction in the coke oven and the catalyst oven When the total amount was calculated, it was 2226 MJ/h. Therefore, it was found that the net calorie of COG after the reaction was 10198 MJ/h, which was 1.45 times that of the COG before the reaction. Thus, combining the coke oven and the catalyst reactor, further, the molar ratio before the coke oven _(CO 2 /C)=0.5 next, the molar ratio before the catalyst reactor and _(CO 2 /C)=0.5 It was found that the COG calories can be further increased by supplying each of the following carbon dioxides.

(Example 7)
In Example 2, the same procedure as in Example 2 was performed except that the control was performed to supply 158 Nm ³ /h of carbon dioxide corresponding to the molar ratio (CO ₂ /C)=0.5 from before the catalytic furnace. did.

As a result, the CO ₂ conversion rate in the catalytic furnace becomes 50%, and the composition of the catalytic reforming COG at the catalytic furnace outlet is H ₂ 20.9%, CH ₄ 7.2%, CO 49.4%, CO ₂ 15.6%, the balance was N ₂ , and the volume was 2.88 times the COG before the reaction. As a result, the calorie of COG after the reaction was 13872 MJ/h on a dry basis. Here, each of the energy for heating CO ₂ at room temperature to the coke oven top space temperature of 950° C. and the catalyst oven temperature of 800° C., and the energy required to compensate the endothermic reaction in the coke oven and the catalyst oven When the total amount was calculated, it was 2831 MJ/h. Therefore, it was found that the net calorie of COG after the reaction was 11041 MJ/h, which was 1.57 times that of the COG before the reaction. Thus, combining a coke oven and a catalyst reactor, further comprising a molar ratio in the previous coke oven _(CO 2 /C)=1.0 next, the molar ratio before the catalyst reactor and _(CO 2 /C)=0.5 It was found that the COG calories can be further increased by supplying carbon dioxide respectively.

(Example 8)
Example 2 was carried out in the same manner as in Example 2 except that the catalyst furnace was installed at a location about 20 m away from the coke oven.

Although the temperature of the reforming COG in the coke oven has dropped from 800°C to 500°C because the catalyst furnace is 20 m away from the coke oven, the piping is insulated with heat insulating material. Was required in addition. Here, the energy to heat the room temperature CO ₂ to the coke oven top space temperature of 950° C., the energy required to compensate the endothermic reaction in the coke oven and the catalyst oven, and the coke oven reforming at 500° C. When the total amount of energy for heating the COG to a catalyst furnace temperature of 800° C. was calculated, it was 2732 MJ/h. Therefore, it was found that the net calorie of COG after the reaction was 9684 MJ/h, which was 1.38 times that of the COG before the reaction. From this, it was found that even if the catalyst furnace was separated from the coke oven to some extent, it did not significantly affect the calorie increase of the reformed COG.

(Example 9)
In the same manner as in Example 1, except that about 30 t of coal obtained by impregnating about 27.6 t of coal pre-dried by DAPS with about 2.4 t of formic acid anhydride was charged in the carbonization chamber of the coke oven in Example 1. Carried out.

As a result, it was found that the net calorie of COG after the reaction was 9113 MJ/h, which was 1.30 times that of the COG before the reaction. Thus, it was found that COG calories can be further increased by adding formic acid to coal in advance.

(Example 10)
The procedure of Example 1 was repeated, except that the catalyst amount in the catalytic reaction step was quintuple and the space velocity SV in the catalytic furnace was 100 h ⁻¹ .

As a result, compared with the result at the space velocity SV=500 h ⁻¹ in Example 1, the CO ₂ conversion rate in the catalytic furnace was 70%, and the composition of the catalytically reformed COG at the outlet of the catalytic furnace was H ₂ 36%. , CH ₄ 13%, CO 35%, CO ₂ 4% and the balance N ₂ , and the volume was 1.77 times that of COG before the reaction. It was also found that the net calorie of COG after the reaction was 8278 MJ/h, which was 1.18 times that of the COG before the reaction. When the space velocity SV is 100 h ^-1 , the reactivity is improved, and thus the calorie of COG can be increased. However, since the amount of the catalyst is 5 times, the size of the catalytic reactor is also 5 times, and the equipment cost is increased.

(Example 11)
Example 1 was carried out in the same manner as in Example 1 except that the catalyst amount in the catalytic reaction step was ⅕ and the space velocity SV in the catalytic furnace was 2500 h ⁻¹ .

As a result, compared with the result at space velocity SV=500 h ⁻¹ in Example 1, the CO ₂ conversion rate in the catalytic furnace was 25%, and the composition of the catalyst reformed COG at the catalytic furnace outlet was H ₂ 33%. , CH ₄ 17%, CO 27%, CO ₂ 11%, balance N ₂ , and the volume was 1.73 times that of COG before the reaction. It was also found that the net calorie of COG after the reaction was 8078 MJ/h, which was 1.15 times that of the COG before the reaction. When the space velocity SV is 2500 h ⁻¹ , the reactivity decreases, so the effect of increasing the calorie of COG is small, but since the amount of catalyst is 1/5, the equipment can be made compact and the equipment cost is significantly reduced. It led to a reduction.

(Example 12)
In Example 1, the coal filled in the carbonization chamber of the coke oven was analyzed for the ash composition of the coal, and the concentrations of CaO and MgO were 2.1% by mass and 0.6% by mass with respect to the alkaline earth metal. And the same procedure as in Example 1 was performed except that the Fe ₂ O ₃ concentration was changed to 3.5% by mass.

As a result, the CO ₂ conversion proceeded at 10% in the coke oven. At this time, the total amount of energy for heating CO ₂ at room temperature to the coke oven top space temperature of 950° C. and the total energy required for compensating the endothermic reaction in the catalytic furnace was 1461 MJ/h. It was found that the net calorie of COG after the reaction was 8171 MJ/h, which was 1.16 times that of the COG before the reaction. From this, even if the concentrations of CaO and MgO and the concentration of Fe ₂ O ₃ were low in the ash composition of the coal used, if the reactivity in the coke oven progressed to a certain extent, the amount of COG calories was increased. I knew I could do it.

(Example 13)
In Example 1, the coal filled in the carbonization chamber of the coke oven, in the ash composition analysis value of the coal, the concentrations of CaO and MgO with respect to the alkaline earth metal are 1.5% by mass and 0.4% by mass, respectively. And the same procedure as in Example 1 was performed except that the Fe ₂ O ₃ concentration was changed to 25% by mass.

As a result, the CO ₂ conversion rate progressed by 50% in the coke oven. At this time, the total amount of energy for heating CO ₂ at room temperature to the coke oven top space temperature of 950° C. and the total energy required for compensating the endothermic reaction in the catalytic furnace was 1594 MJ/h. It was found that the net calorie of COG after the reaction was 8406 MJ/h, which was 1.20 times that of the COG before the reaction. From this, it was found that, in the ash composition of the coal used, when the concentration of Fe ₂ O ₃ was high, the reactivity in the coke oven was high and the calorie of COG could be increased.

(Example 14)
In Example 1, the coal filled in the carbonization chamber of the coke oven, in the ash composition analysis value of the coal, the concentration of CaO and MgO is 12 mass% and 3.5 mass% with respect to alkaline earth metal, The same procedure as in Example 1 was performed except that the Fe ₂ O ₃ concentration was changed to 3.1% by mass.

As a result, the CO ₂ conversion rate progressed by 50% in the coke oven. At this time, the total amount of energy for heating CO ₂ at room temperature to the coke oven top space temperature of 950° C. and the total energy required for compensating the endothermic reaction in the catalytic furnace was 1594 MJ/h. It was found that the net calorie of COG after the reaction was 8425 MJ/h, which was 1.20 times that of the COG before the reaction. From this, it was found that, in the ash composition of the coal used, when the concentration of CaO was high, the reactivity in the coke oven was high and the calorie of COG could be increased.

(Example 15)
In Example 1, a 15% Ca(OH) ₂ aqueous solution prepared in advance was sprayed on the coal, and the coal whose water content was adjusted by CMC was charged into the carbonization chamber of the coke furnace for about 30 t, and the combustion chambers on both sides of the carbonization chamber were filled. The temperature from the above was lowered to about 1000° C., and dry distillation was started. When the ash composition analysis in the coal was performed, the concentrations of CaO and MgO were 43.8% by mass and 1.2% by mass, respectively, and the Fe ₂ O ₃ concentration was 3.5% by mass with respect to the alkaline earth metal. Was performed in the same manner as in Example 1 except that the above was changed.

At this time, the temperature of the top space of the coke oven was about 850° C., but the conversion rate of CO ₂ in the coke oven was 40%.

As a result, the total amount of energy for heating CO ₂ at room temperature to the coke oven top space temperature of 850° C. and the total energy required for compensating the endothermic reaction in the catalytic furnace was 1440 MJ/h. It was found that the net calorie of COG after the reaction was 8513 MJ/h, which was 1.21 times that of the COG before the reaction. From this, in the ash composition in the coal used, by adding the Ca component in advance, the reaction in the coke oven can proceed at a lower temperature and the additional energy can be suppressed, so the calories of COG can be reduced. It turns out that the amount can be increased.

(Example 16)
In Example 1, about 700 kg of CaCO ₃ was filled on the coal filled in the carbonization chamber of the coke oven so that the height of the layer of limestone was about 100 mm. The same procedure as in Example 1 was performed except that the heating was lowered to about 1000° C. and the dry distillation was started.

At this time, the temperature of the top space of the coke oven was about 850° C., but the conversion rate of CO ₂ in the coke oven was 50%.

As a result, the total amount of energy required to heat the room temperature CO ₂ to the coke oven top space temperature of 850° C. and the energy required to compensate the endothermic reaction in the catalytic furnace was 1554 MJ/h. It was found that the net calorie of COG after the reaction was 8504 MJ/h, which was 1.21 times that of the COG before the reaction. As a result, the presence of the compound containing Ca as a main component at the location where CO ₂ comes into contact with COG or tar allows the reaction in the coke oven to proceed at a lower temperature and suppresses additional energy. Therefore, it was found that the calorie of COG can be increased.

The results obtained in the above-described Examples and Comparative Examples are summarized in Table 1 below and shown in the graphs of FIGS. 4 and 5. In addition, the notation “alkaline earth metal” in the “Remarks” column of Table 1 below represents the total concentration of CaO and MgO. From these results, it is clear that by using the coke manufacturing equipment and the carbon dioxide reduction method according to the embodiment of the present invention, it is possible to reduce carbon dioxide at room temperature in a large amount and further increase COG calories. Became.

Although the preferred embodiments of the present invention have been described above in detail with reference to the accompanying drawings, the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can come up with various alterations or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

1 Coke Manufacturing Equipment 10 Coke Oven 20 Catalyst Furnace 30,40 Control Valve 50 Controller 101 Coking Chamber 103 Coal Insertion Port 105 Top Space 107 Outlet Port 109 Furnace Top 111 Coke Reforming COG
113 Upcomer pipe 115 Carbon dioxide supply port 117 Dry main 119 Catalytic reforming COG

Claims (13)

Supplying carbon dioxide to a carbonization chamber filled with coal in a coke oven, reacting the carbon dioxide with carbon components and hydrogen present in the carbonization chamber to convert into carbon monoxide, a coke oven reaction step,
The coke oven gas containing the unreacted carbon dioxide supplied to the carbonization chamber is supplied to a catalyst furnace provided with a catalyst to reform the unreacted carbon dioxide into carbon monoxide. Quality process,
And a method for reducing carbon dioxide. The method for reducing carbon dioxide according to claim 1, wherein the carbon dioxide supplied to the carbonization chamber has a molar ratio with respect to a carbon component in the coke oven gas of more than 0.2 and 2.0 or less. The method for reducing carbon dioxide according to claim 1 or 2, wherein the space velocity of the coke oven gas containing the unreacted carbon dioxide supplied to the catalyst furnace is 250 h ^-1 or more and 2000 h ^-1 or less. The carbon dioxide according to any one of claims 1 to 3, wherein carbon dioxide is further supplied to the catalyst furnace together with a coke oven gas containing an unreacted portion of the carbon dioxide in the catalyst reforming step. How to reduce. The carbon dioxide reduction method according to claim 4, wherein the carbon dioxide supplied to the catalyst furnace has a molar ratio with respect to a carbon component in the coke oven gas of 0.1 or more and 1.0 or less. The carbonization chamber is provided with an outlet for discharging coke produced from the coal, and a riser for discharging coke oven gas containing unreacted carbon dioxide,
The carbon dioxide supplied to the carbonization chamber of the coke oven is supplied to the inside of the carbonization chamber from a predetermined position closer to the discharge port than the rising pipe. The method for reducing carbon dioxide according to 1. The method for reducing carbon dioxide according to claim 6, wherein the carbon dioxide is supplied to the furnace top space of the carbonization chamber. The concentration of CaO and MgO in the obtained ash composition is 3 mass% or more in total when the ash of the coal filled in the carbonization chamber is measured by a fluorescent X-ray analysis method. 8. The method for reducing carbon dioxide according to any one of 7 above. The concentration of Fe ₂ O ₃ in the obtained ash composition is 5 mass% or more when the ash of the coal filled in the carbonization chamber is measured by a fluorescent X-ray analysis method. The method for reducing carbon dioxide according to any one of 1. The carbon dioxide reduction method according to any one of claims 1 to 9, wherein a Ca component is contained in the coal filled in the carbonization chamber prior to filling. The carbon dioxide reduction method according to any one of claims 1 to 10, wherein a Ca-containing material is installed on a surface layer of the filled coal after the coal is filled in the carbonization chamber. The method for reducing carbon dioxide according to any one of claims 1 to 11, wherein formic acid is contained in the coal filled in the carbonization chamber prior to filling. It has a carbonization chamber in which carbon dioxide is supplied to the coal being filled, and in the carbonization chamber, coke is produced from the filled coal and the carbon dioxide is a carbon component present in the carbonization chamber. And a coke oven that is converted to carbon monoxide by reacting with hydrogen,
A catalyst is provided inside, and the coke oven gas containing the unreacted carbon dioxide supplied to the carbonization chamber is supplied to the catalyst to convert the unreacted carbon dioxide into carbon monoxide. And a catalytic furnace
Depending on the reaction degree of the reaction inside the carbonization chamber, a carbon dioxide supply control mechanism for controlling the supply amount of the carbon dioxide supplied to the carbonization chamber,
Coke manufacturing equipment equipped with.

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