JP7415133B2 - Carbon dioxide reduction method - Google Patents

Description

The present invention relates to a method for reducing carbon dioxide.

The steel industry is an energy-intensive industry, and approximately 40% of the waste heat from the integrated blast furnace steelmaking process is unused waste heat. Among the unused waste heat, sensible heat of high-temperature coke oven gas (COG) generated from a coke oven is a heat source that is easily recovered but has not been used in the past. Conventionally, the sensible heat of high-temperature coke oven gas has hardly been utilized, and in most cases the gas has been processed and utilized after cooling. On the other hand, as the reduction of carbon dioxide emissions has become an issue in recent years, the steel industry is an industry that emits a large amount of carbon dioxide, so the development of technology to fix large amounts of carbon dioxide and make it valuable has been attracting attention. There is.

For example, Patent Document 1 below discloses a method in which carbon dioxide is supplied to a carbonization chamber of a coke oven and the amount of coke oven gas is increased using sensible heat in the coke oven. According to Patent Document 1, the amount of carbon dioxide supplied is 0.1 to 10% of the amount of COG generated. In Patent Document 1, carbon dioxide generated in the carbonization process of coal is reduced by supplying carbon dioxide equivalent to 0.002 to 0.2 when converted to the ratio of tar and hydrocarbons to carbonaceous substances in COG (CO ₂ /C). It is said that a boudoir reaction (CO ₂ +C→2CO) occurs in which carbon dioxide reacts with the high-temperature powder coke and deposited carbon.

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

Furthermore, in the following Patent Documents 3 and 4, in order to remove carbon attached to the inner wall of the top space of the coking chamber of the coke oven, carbon generated in the combustion chamber of the coke oven containing CO ₂ and H ₂ O is disclosed. By supplying a part of the combustion exhaust gas (3.5 or 80 Nm ³ /h・kiln. CO ₂ is 25% of it) to the carbonization chamber, carbon attached to the inner wall of the furnace top space is removed and the coke oven is heated. It is said that it can be recovered as gas.

In addition, in Patent Document 5 below, carbon dioxide is used in the dry quenching of coke to cool the coke through an endothermic reaction by the boudoir reaction, convert carbon dioxide into carbon monoxide, and further convert the converted monoxide into carbon monoxide. It is disclosed that carbon is recovered and used for heating the carbonization chamber of a coke oven.

On the other hand, a method of reacting high-temperature COG and carbon dioxide using a catalyst is disclosed by the present inventors, for example, in the following Patent Documents 6 to 8. The present inventors used a tar-containing gas reforming catalyst consisting of a mixture of nickel and magnesium with various metal components, alumina, etc. as a third component, to convert tar-containing COG or biomass gasification gas. Discloses a method of reforming. For example, Patent Document 6 and Patent Document 7 below disclose tar-containing gas reforming catalysts made of oxides containing nickel, magnesium, and aluminum. Moreover, the following Patent Document 8 discloses a tar-containing gas reforming catalyst made of an oxide containing nickel, magnesium, cerium, zirconium, and aluminum. The main focus of both catalysts is to amplify the hydrogen contained in COG, and in addition to the water vapor and carbon dioxide contained in COG, either water vapor or carbon dioxide is added from the outside to reform tar. Efforts are being made to improve activity.

Special Publication No. 2013-515834 JP 2017-115125 Publication Japanese Patent Application Publication No. 3-212486 Japanese Patent Application Publication No. 3-212487 Special table 2014-528503 publication Japanese Patent Application Publication No. 2010-17701 International Publication No. 2010/035430 Japanese Patent Application Publication No. 2011-212574

However, in the technologies disclosed in Patent Documents 1 to 5, carbon dioxide is reacted only in a coke oven, so if too much carbon dioxide is supplied, unreacted carbon dioxide remains that is not converted into carbon monoxide. The amount becomes too large. Therefore, according to studies by the present inventors, there was a problem in that only 10% of carbon dioxide could be supplied at most to COG. In addition, Patent Document 2 does not mention the amount or range of supply of carbon dioxide, and does not mention whether the energy required to heat the supplied carbon dioxide (emission of carbon dioxide) is taken into account. , 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, and therefore a large amount of carbon dioxide cannot be supplied.

Furthermore, regarding the technologies disclosed in Patent Documents 6 to 8, the tar reforming reaction is an endothermic reaction, and in order to proceed with the reaction by adding water vapor or carbon dioxide from the outside, new energy is required. is necessary. Here, in the above reaction, carbon dioxide is generated as the reaction progresses, but the above Patent Documents 6 to 8 do not mention the amount of carbon dioxide generated. The present inventors further investigated the reaction of COG and carbon dioxide using only the catalysts described in Patent Documents 6 to 8, and found that when the energy required for the reaction is taken into account, carbon dioxide It became clear that there is room for further improvement in reducing emissions.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to use carbon dioxide, which can further increase the calorie content of coke oven gas even after subtracting the input energy. The goal is to provide a method of giving back.

In order to solve the above-mentioned problems, the present inventors have intensively studied a method for reducing a large amount of carbon dioxide using a coke oven and a catalyst. As a result, we were able to obtain two new findings shown in (a) and (b) below.

(a) By supplying carbon dioxide to the coking chamber of a coke oven, the carbon dioxide reacts with the coal or tar and hydrogen generated by carbonization of coal in the coking chamber, converting carbon dioxide into carbon monoxide. At the same time, the volume of COG increases.
(b) By using a catalyst to react the high-temperature COG containing unreacted carbon dioxide immediately after it comes out of the carbonization chamber, the tar and hydrocarbons in the COG react with carbon dioxide, resulting in monoxide oxidation. It is converted into carbon, and the volume of COG is further amplified.

Based on the two new findings shown in (a) and (b) above, the present inventors came up with the idea that it is possible to increase the calories of COG while improving the reaction rate of carbon dioxide. In other words, by combining the reaction inside the coke oven and the reaction on the catalyst, it is possible to efficiently convert carbon dioxide and increase the calorie content of COG, including the generation of carbon dioxide using the new energy required for the reaction. became clear.

COG produced by such a carbon dioxide reduction method can further improve the calorie content of COG even after subtracting both the energy required to raise room temperature carbon dioxide to the reaction temperature and the energy required for the endothermic reaction. can.
The gist of the present invention, which was completed based on the above findings, is as follows.

(1) A coke oven reaction in which carbon dioxide is supplied to a coking chamber filled with coal in a coke oven, and the carbon dioxide is reacted with carbon components and hydrogen present in the coking chamber to convert it into carbon monoxide. and supplying the coke oven gas containing the unreacted carbon dioxide supplied to the carbonization chamber to a catalyst furnace provided with a catalyst, and reforming the unreacted carbon dioxide into carbon monoxide. a catalytic reforming step, the carbonization chamber includes an outlet for discharging coke produced from the coal, and a riser pipe for discharging coke oven gas containing unreacted carbon dioxide; is provided, and 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 riser pipe, and A method for reducing carbon dioxide, wherein the coal to be filled contains formic acid prior to charging .
(2) A coke oven reaction in which carbon dioxide is supplied to a coking chamber filled with coal in a coke oven, and the carbon dioxide is reacted with carbon components and hydrogen present in the coking chamber to convert it into carbon monoxide. and supplying the coke oven gas containing the unreacted carbon dioxide supplied to the carbonization chamber to a catalyst furnace provided with a catalyst, and reforming the unreacted carbon dioxide into carbon monoxide. a catalytic reforming step, the carbonization chamber includes an outlet for discharging coke produced from the coal, and a riser pipe for discharging coke oven gas containing unreacted carbon dioxide; is provided, and 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 riser pipe, and is filled into the carbonization chamber. A method for reducing carbon dioxide, wherein the coal is made to contain a Ca component before being charged.
(3) A coke oven reaction in which carbon dioxide is supplied to a coke oven filled with coal, and the carbon dioxide is reacted with carbon components and hydrogen present in the coke oven to convert it into carbon monoxide. and supplying the coke oven gas containing the unreacted carbon dioxide supplied to the carbonization chamber to a catalyst furnace provided with a catalyst, and reforming the unreacted carbon dioxide into carbon monoxide. a catalytic reforming step, the carbonization chamber includes an outlet for discharging coke produced from the coal, and a riser pipe for discharging coke oven gas containing unreacted carbon dioxide; 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 riser, and the carbon dioxide is supplied to the carbonization chamber from a predetermined position closer to the discharge port than the riser pipe. A method for reducing carbon dioxide, which comprises, after filling coal, installing a Ca-containing material on the surface layer of the filled coal.
( 4 ) Any of (1) to (3) , wherein the carbon dioxide supplied to the carbonization chamber has a molar ratio of more than 0.2 to 2.0 with respect to the carbon component in the coke oven gas. The method for reducing carbon dioxide according to item 1 .
( 5 ) Any one of (1) to (4), wherein the coke oven gas containing unreacted carbon dioxide supplied to the catalytic furnace has a space velocity of 250 h ^-1 or more and 2000 h ^-1 or less. The method for reducing carbon dioxide described in .
( 6 ) In any one of (1) to ( 5 ), in the catalytic reforming step, carbon dioxide is further supplied to the catalytic furnace together with coke oven gas containing unreacted carbon dioxide. The carbon dioxide reduction method described.
( 7 ) The carbon dioxide according to ( 6 ), wherein the carbon dioxide supplied to the catalytic furnace has a molar ratio of 0.1 to 1.0 with respect to the carbon component in the coke oven gas. Reduction method.
( 8 ) The method for reducing carbon dioxide according to any one of (1) to ( 7 ), wherein the carbon dioxide is supplied to the furnace top space of the carbonization chamber.
( 9 ) When the ash of the coal filled in the carbonization chamber is measured by X-ray fluorescence analysis, the total concentration of CaO and MgO in the resulting ash composition is 3% by mass or more, ( The method for reducing carbon dioxide according to any one of 1) to ( 8 ).
( 10 ) When the ash of the coal filled in the carbonization chamber is measured by X-ray fluorescence analysis, the concentration of Fe ₂ O ₃ in the obtained ash composition is 5% by mass or more, (1 ) to ( 9 ). The method for reducing carbon dioxide according to any one of (9).

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

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram schematically showing the configuration of coke production equipment according to an embodiment of the present invention. FIG. 2 is an explanatory diagram schematically showing an example of the configuration of a coke oven and a catalyst furnace in the coke production equipment according to the embodiment. It is a flowchart which showed an example of the flow of the reduction method of carbon dioxide concerning the same embodiment. It is a graph diagram showing the net calories of COG and their ratios in Examples. It is a graph diagram showing the net calories of COG and their ratios in a comparative example.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Note that, in this specification and the drawings, components having substantially the same functional configurations are designated by the same reference numerals and redundant explanation will be omitted.

In the method for reducing carbon dioxide according to an embodiment of the present invention, carbon dioxide is supplied to the carbonization chamber of a coke oven, and coal filled in the carbonization chamber of the coke oven, tar and hydrogen generated by carbonization of the coal, and carbon dioxide By reacting with, carbon dioxide is converted to carbon monoxide. In addition, in the carbon dioxide reduction method according to the embodiment of the present invention, high temperature coke oven gas (COG) containing unreacted carbon dioxide is further reformed with a catalyst, and by the reaction between hydrocarbons and carbon dioxide, 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 as the above reaction progresses.

(About coke manufacturing equipment)
<About the overall configuration of coke manufacturing equipment>
Below, first, the overall configuration of 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 coke production equipment according to the present embodiment.

As schematically shown in FIG. 1, the coke production facility 1 according to the present embodiment includes a coke oven 10 and a catalytic 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 filled coal becomes coke by being carbonized in the coke oven 10. Further, in the process of turning coal into coke, COG (coke oven reformed COG) containing hydrocarbons such as methane and tar is generated. In the coke manufacturing equipment 1 according to the present embodiment, carbon dioxide is supplied into the coke oven 10 to cause COG or hydrogen to react with the carbon dioxide, thereby reducing the carbon dioxide to carbon monoxide. Here, the 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 production facility 1 according to the present embodiment, a catalyst furnace 20 provided with a reforming catalyst for reforming hydrocarbons is provided at a position downstream of and near the coke oven 10. The coke oven reformed COG generated in the coke oven 10 is supplied to the catalytic furnace 20 . In addition to components such as hydrocarbons and tar, the coke oven reformed COG also contains carbon dioxide that has not reacted inside the coke oven 10. By supplying such coke oven reformed COG into the catalyst furnace 20, the tar and hydrocarbons in the coke oven reformed COG react with carbon dioxide via 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. Moreover, COG after unreacted carbon dioxide has been reduced to carbon monoxide is discharged to the outside of the catalytic furnace 20 as catalytically reformed COG.

Here, in the coke production equipment 1 according to the present embodiment, in order to more efficiently proceed with the reduction reaction of carbon dioxide in the catalyst furnace 20, for the in-coke oven reformed COG supplied to the catalyst furnace 20, It is preferable to further supply carbon dioxide. Here, it is preferable that the amount of carbon dioxide supplied to the reforming COG in the coke oven is controlled by a control valve 40 as an example of a carbon dioxide supply control mechanism.

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

The overall configuration of the coke production facility 1 according to the present embodiment has been briefly described above. Below, with reference to FIGS. 2 and 3, the configuration of the coke oven and catalytic furnace in the coke production equipment according to the present embodiment, and the method for reducing carbon dioxide carried out in the coke oven and catalytic furnace will be explained in more detail. Explain.

<Example of configuration of coke oven and catalytic furnace>
Hereinafter, an example of a specific configuration of a coke oven and a catalyst furnace in the coke production facility 1 according to the present embodiment will first be described with reference to FIG. 2. FIG. 2 is an explanatory diagram schematically showing an example of the configuration of a coke oven and a catalyst furnace in the coke production equipment according to the present 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. Further, a void remains in the upper part of the carbonization chamber 101 after being filled with coal, and this void is also referred to as a furnace top space 105. Normally, in order to increase coke manufacturing efficiency in the coke oven 10, coal is often filled into the carbonization chamber 101 so that the oven top space 105 is made as small as possible. For example, Japanese Patent Application Laid-open No. 2004-124001 discloses that the height of the carbonization chamber is usually around 6m to 7m, and the height at which coal is charged is about 300mm to 350mm below 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, and becomes coke. The produced coke is discharged out of the furnace from the discharge port 107 provided in the carbonization chamber 101 (more specifically, from the opening created by opening the furnace cover 109 provided in the discharge port 107). Ru. In addition, COG (coke oven reformed COG) 111 containing tar and hydrocarbons generated in the process of producing coke is transported from a riser 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. Inside the carbonization chamber 101, the supplied carbon dioxide reacts with tar and hydrogen generated by carbonization of coal, as well as with the coal itself, and is reduced to carbon monoxide.

In the carbonization chamber 101 of the coke oven 10, the boudoir reaction shown in the following equation 101 occurs, in which carbon dioxide reacts with coal and attached carbon, tar, and hydrogen generated in the carbonization of coal, and the reaction between carbon dioxide and tar occurs. A dry reforming reaction of hydrocarbons (particularly tar) as shown in Equation 103 below, in which carbon dioxide and hydrogen react, and a reverse shift reaction as shown in Equation 105, in which carbon dioxide and hydrogen react, proceed. Through these reactions, 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 (Formula 105)

In addition, the carbon dioxide supplied to the carbonization chamber 101 is often not all reduced to carbon monoxide, and the unreacted carbon dioxide is transported from the riser pipe 113 to the furnace together with the generated COG 111 in the coke oven. It is expelled to the outside.

The amount of carbon dioxide (supply amount) supplied to the carbonization chamber 101 is controlled according to the degree of reaction (reaction rate) of the above three types of reactions within 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 within the carbonization chamber 101. In other words, the amount of COG (coke This also means that the amount of carbon dioxide supplied to the carbonization chamber 101 is controlled according to the space velocity (SV) of the in-furnace reforming COG 111.

The amount of carbon dioxide supplied to the carbonization chamber 101 is such that the molar ratio (CO ₂ /C) of hydrocarbons such as tar and methane to carbon components in COG generated during carbonization of coal is more than 0.2. preferable. By setting the molar ratio (CO ₂ /C) to more than 0.2, it is possible to improve the throughput of carbon dioxide and obtain the effect of increasing the calories of COG more fully. The molar ratio (CO ₂ /C) is more preferably 0.5 or more, and 0.7 or more, from the viewpoint of increasing the amount of carbon dioxide reduction 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 to raise the temperature of the supplied carbon dioxide to the reaction temperature and the energy to compensate for the endothermic reaction are suppressed, and these energies are subtracted. Even so, it is possible to more reliably increase the calories of COG after the reaction than before the reaction. If the calorie of COG after the reaction is smaller than before the reaction, it will be important to increase the amount of catalyst in the subsequent catalytic reaction step to increase the amount of reaction, which will result in higher costs. 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 even more preferable.

Carbon dioxide also reacts with hydrogen through a reverse shift reaction as shown in Equation 105 above, but since the ratio of hydrocarbons and hydrogen in the composition of COG is almost fixed, the ratio of carbon dioxide to carbon is adjusted as shown above. If this is determined, the ratio of carbon dioxide to hydrogen can also be approximately determined. Note that since COG actually contains water vapor, steam reforming of hydrocarbons is also progressing.

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

In the coking chamber 101 of the coke oven 10, there is a pusher side (extrusion side, the side where the riser pipe 113 is located) in the extrusion direction (direction from the riser pipe 113 toward the discharge port 107 in FIG. A furnace cover 109 is provided on each coke side (the discharge side, the side where the discharge port 107 is located) to prevent coal and generated COG from leaking from the coking chamber 101. For example, a carbon dioxide supply port 115 as schematically shown in FIG. 2 is provided on the furnace lid 109 located on the opposite side of the riser pipe 113 into which the generated COG flows, and the May be supplied. The carbon dioxide supply port 115 is preferably provided at one or more locations on the furnace lid 109 of each carbonization chamber, and may be divided into several locations in the height direction. In particular, it is more preferable to supply carbon dioxide from a lower position on the furnace lid 109 because the residence time of carbon dioxide in the carbonization chamber 101 of the coke oven 10 becomes longer and the reaction can be performed more efficiently. The carbon dioxide supply port 115 may be provided in addition to the furnace lid by arranging a supply nozzle in the furnace top space 105 through which COG generated in the coke oven flows.

Inside the carbonization chamber 101, coal is normally carbonized at a temperature of about 1000 to 1200°C, and in the furnace top space 105, the temperature is usually within a range of about 800 to 1000°C. The higher the temperature, the easier the reduction of carbon dioxide will progress, so from this point of view as well, it is more preferable to supply carbon dioxide from a lower position in the carbonization chamber 101.

In the coke manufacturing equipment 1 according to the present embodiment, carbonization is performed near the outlet side of the riser pipe 113 of the coke oven 10 and in front of the position where COG is subjected to gas cooling (dry main 117 in FIG. 2). A catalytic furnace (catalytic reactor) 20 provided with a hydrogen reforming catalyst is provided. By providing the catalytic furnace 20 near the riser pipe 113, the sensible heat of COG discharged from the coke oven 10 and in the above-mentioned high temperature state 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 hydrocarbon reforming catalyst that is resistant to sulfur poisoning and is resistant to hydrogen sulfide at a high concentration of 0.2 to 0.3% by volume contained in COG. Examples of such sulfur poisoning-resistant hydrocarbon reforming catalysts include the catalysts disclosed in Patent Documents 4 to 6 mentioned above. The shape of the catalyst and the type of reaction are not particularly limited. However, since the tar in the reformed COG 111 in the coke oven is likely to thermally decompose and cause carbon precipitation, if it is a fixed bed type, it is preferable to form it into pellets, tablets, rings, honeycombs, etc. rather than powder form. Further, in the case of a fluidized bed type, it is preferable to use a powdered catalyst having an average particle size of 150 μm or less.

In addition, in the catalytic furnace 20, in addition to the reaction between hydrocarbons such as tar and methane and carbon dioxide in the dry reforming of hydrocarbons shown in equation 103 above, monoxide reaction as shown in equation 107 below is carried out. A shift reaction in which carbon and water vapor react mainly proceeds.

CO+ _H2O → _CO2 + _H2 ... (Formula 107)

In order to more reliably reduce the carbon dioxide contained in the coke oven reformed COG 111 to carbon monoxide, it is preferable to suppress the progress of the shift reaction shown in equation 107 above. For this purpose, the amount of water vapor in the coke oven reformed 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 that has been dried in advance using CMC (Coal Moisture Control) or DAPS (Dry-cleaned and Agglomerated Precompaction System).

In this 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 reduce carbon dioxide more efficiently 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 lower, excessive energy required for heating can be more reliably suppressed, and further generation of carbon dioxide can be more reliably prevented. The reaction temperature in the catalyst furnace 20 is more preferably 800°C or lower. It is more preferable to compensate only for the energy of the endothermic reaction by utilizing the sensible heat of the reformed COG 111 in the coke oven at about 800° C., since this does not lead to the generation of excess 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 decomposes and carbon precipitation tends to occur, and the larger the space velocity SV, the more conspicuous the carbon precipitation tends to be. However, by setting the space velocity SV to 2000 h ^-1 or less, it becomes possible to proceed with the tar reforming reaction while suppressing such carbon precipitation more reliably. The space velocity SV is more preferably 1000 h ⁻¹ or less. Note that the space velocity SV can be calculated by gas flow rate (Nm ³ /h)/catalyst volume (m ³ ).

In the carbon dioxide reduction process in the carbonization chamber 101 of the coke oven 10, a portion of the carbon dioxide supplied to the carbonization chamber 101 reacts with a portion of the generated hydrocarbons in the coke oven reformed COG 111. Therefore, when carbon dioxide is supplied into the carbonization chamber 101 of the coke oven 10 at a molar ratio (CO ₂ /C) = 0.5, in the coke oven reforming COG 111 before the catalytic reaction, the molar ratio (CO ₂ /C )=0.3. In addition, when carbon dioxide is supplied to the carbonization chamber 101 of the coke oven 10 at a molar ratio (CO ₂ /C) = 1.0, in the coke oven reforming COG 111 before the catalytic reaction, the molar ratio (CO ₂ /C) =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 that is additionally supplied before the catalyst is determined by the molar ratio (CO ₂ /C) to the carbon components of hydrocarbons such as tar and methane in coke oven reformed COG111 generated by carbonization of coal. It is preferable to set it to 0.1 or more. By setting the molar ratio (CO ₂ /C) of additionally supplied carbon dioxide to 0.1 or more, it becomes possible to increase the amount of carbon dioxide treated in the catalyst furnace 20 more reliably. The amount of additionally supplied carbon dioxide is more preferably 0.2 or more in molar ratio (CO ₂ /C).

In addition, the amount of carbon dioxide additionally supplied before the catalyst is determined based on the molar ratio (CO ₂ /C ) is preferably 1.0 or less. By setting the molar ratio (CO ₂ /C) of additionally supplied carbon dioxide to 1.0 or less, it is more certain that both the energy required to raise the temperature of carbon dioxide and the energy to compensate for the endothermic reaction become excessive. In addition, the amount of unreacted carbon dioxide after the catalytic reaction can be more reliably prevented. As a result, it becomes possible to more reliably reduce carbon dioxide emissions from the process and increase the calorie content of COG. The amount of additionally supplied carbon dioxide is more preferably 0.7 or less in molar ratio (CO ₂ /C).

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

At first glance, in order to reduce a larger amount of carbon dioxide, it may be possible to increase the amount of carbon dioxide supplied into the carbonization chamber of the coke oven without providing a catalytic furnace. However, as mentioned earlier, the top space in the coking chamber of a coke oven is usually small, so if a large amount of carbon dioxide is supplied to the coking chamber of a coke oven, the residence time of carbon dioxide in the coking chamber will be Since carbon dioxide cannot be taken in sufficient amount, carbon dioxide does not react sufficiently in the carbonization chamber, and the calorie content of COG decreases. Therefore, in the coke manufacturing equipment 1 according to the present embodiment, the catalyst furnace 20 is provided at the latter stage of the coke oven 10 to efficiently reduce unreacted carbon dioxide, thereby reducing the amount of carbon dioxide supplied to the carbonization chamber 101 of the coke oven 10. The amount of carbon reaction is increased synergistically. Furthermore, by providing the catalytic furnace 20, the volume of the generated COG is also greatly increased, making it possible to increase the calorie content of the COG.

In this way, the carbon dioxide contained in the reformed COG 111 in the coke oven is efficiently reduced to carbon monoxide, and the catalytically reformed COG 119 with reduced carbon dioxide content is released outside the catalytic furnace 20. be discharged. The discharged catalytic reformed COG 119 is recovered by a dry main 117 and cooled by, for example, spraying with 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 carbonization of coal can be specified as follows. First, before supplying carbon dioxide, COG generated from the carbonization chamber 101 of the coke oven 10 (coke oven reformed COG) is collected and the gas composition of the COG is analyzed using gas chromatography. . In addition, the tar weight obtained by evaporating and removing the solvent used in COG collected by the collection method in accordance with JIS Z 8808 (Method for measuring dust concentration in exhaust gas) is calculated using the liquid collection method. - Analyze by gravimetric method. In addition, carbon, hydrogen, etc. in the collected tar are quantitatively analyzed in accordance with JIS M 8819 (Coal and coke - Elemental analysis method using 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 in advance. Thereby, it is possible to specify the molar amount of carbon components of hydrocarbons such as tar and methane in COG generated during carbonization 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 molar ratio (CO ₂ /C) is controlled to a desired value. be able to.

Also, when measuring the value of the molar ratio (CO ₂ /C) after the fact, 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. It becomes possible to specify the value of the realized molar ratio (CO ₂ /C).

[About various measurement methods]
Each calorie of COG, coke oven reformed COG _, and catalytic reformed COG is determined by analyzing the gas collected in each process using gas chromatography to understand the gas _{concentration} , ) and the gas flow rate (Nm ³ /h) at each step, the gas calorie (MJ/h) for each step can be calculated. The gas flow rate can be easily measured using, for example, a Pitot tube type current meter. More precisely, the standard state gas density (kg/Nm ³ ) is calculated from the gas composition and moisture content measured in accordance with JIS Z 8808, and the gas temperature measured with a K-type thermocouple is used to calculate the high temperature. Convert to gas density (kg/m ³ ) in the state. Next, the flow velocity (m/s) is determined from the dynamic pressure and static pressure of the circulating gas using a Pitot tube and a slight differential pressure Manostar gauge, and the gas flow rate ( ^{Nm 3} /h) can be obtained.

On the other hand, the energy to raise room temperature carbon dioxide to the reaction temperature is determined by the supplied room temperature CO ₂ flow rate (Nm ³ /h), the high temperature COG before CO ₂ mixing whose gas composition is known, and the coke oven renovation. The flow rate (Nm ³ /h) of pure COG and the temperature drop when mixed are calculated, and from the obtained calculation result, the energy required to raise the temperature to the reaction temperature can be determined. In addition, the energy required for the endothermic reaction depends on the gas composition of COG raised to the reaction temperature after supplying carbon dioxide, COG reformed in a coke oven, or reformed COG in a coke oven after supplying carbon dioxide. The reaction heat (endotherm) can be estimated from the gas composition changed by Kirchhoff's law, and the energy to raise the endotherm to the reaction temperature can be determined.

The calorie of COG before carbon dioxide supply is E ₀ , the calorie of COG reformed in the coke oven is E _CO , the calorie of catalytically reformed COG is E _CAT , and 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 catalytic 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 process can be expressed as E _CO ^NET = E _CO - (e ₁ + e ₂ ), and the net calorie E _CAT ^NET in the catalytic reforming process can be expressed as 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 coke oven reaction process can be calculated by E _CO ^NET /E ₁ , and the calorie ratio before and after the reaction, including the catalytic 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, since the higher the calorie ratio is, the more it can be used as an energy source for various purposes, there is no particular restriction on the upper limit value.

An example of a specific configuration of the coke oven and catalyst furnace in the coke production facility 1 according to the present embodiment has been described above in detail with reference to FIG. 2.

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

As shown in FIG. 3, the method of reducing carbon dioxide carried out in the coke production facility 1 as described above includes the coke oven reaction step (step S101) in the coke oven 10 and the catalytic reforming process in the catalytic furnace 20. (Step S103).

In the coke oven reaction step (step S101), carbon dioxide is supplied to the coking chamber 101 filled with coal of the coke oven 10, and the carbon dioxide is reacted with carbon components and hydrogen present in the coking chamber 101. This is the process of converting it into carbon monoxide.

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

Here, the details of the coke oven reaction step and the catalytic reforming step are the same as those described above, and therefore 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 explained above with reference to FIG. 3.

<About the coal used>
Next, the coal to be filled into the carbonization chamber 101 of the coke oven 10 will be briefly described.
Any method can be used to analyze the ash composition of the coal to be filled into the carbonization chamber 101 of the coke oven 10, but the accuracy required for implementing the coke manufacturing equipment 1 and the carbon dioxide reduction method according to the present embodiment may be used. When performing the analysis, it is convenient to use fluorescent X-ray analysis. Normally, it is difficult to accurately analyze the light elements up to the second period of the periodic table (excluding hydrogen, helium, nitrogen, and oxygen) using fluorescent X-ray analysis, but it is difficult to accurately analyze the composition of ash in coal. There is no problem because it does not contain light elements. Note that similar results can be obtained within the measurement error range by using ICP emission spectrometry. No matter which measurement method is used, it is not possible to determine the valence and state of existence of each element, so the mass ratio of each element in terms of oxide is treated as the composition of each coal.

Coal can be mined from coal mines all over the world. Prior to charging coal into the carbonization chamber 101 of the coke oven 10, as mentioned earlier, it is preferable to dry the coal to be used using 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 a high carbon dioxide adsorption ability, they can further improve carbon dioxide reactivity.

In the ash composition of coal to be charged into a coke oven, the concentration of CaO and MgO (converted 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, it becomes possible to further improve the reactivity of carbon dioxide. In order to further improve the reactivity of carbon dioxide, it is more preferable that the total concentration of CaO and MgO in the ash composition when analyzed by X-ray fluorescence is 6% by mass or more.

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

Examples of the above Ca component and Mg component include 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 . I can list things.

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

The Ca-containing substance 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 within the carbonization chamber 101, Ca(OH) ₂ and CaCO ₃ can decompose and change into CaO. On the other hand, due to the presence of water vapor and carbon dioxide in the coexisting gases, the reactions shown in Equations 109 and 111 below proceed, so that Ca changes into various compounds during carbonization. it is conceivable that.

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

Furthermore, 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% by mass or more. Fe ₂ O ₃ may be originally contained in the coal used, or may be pre-mixed before being charged into the carbonization chamber 101 of the coke oven 10 . The premixed iron source may be iron ore. However, in a typical indoor coke oven, at carbonization temperatures of 1150°C or higher, silica, which is the main component of the silica bricks used, reacts with iron to produce fayalite with a low melting point. Damage may result. Therefore, it is more preferable to carry out at least one of reducing the concentration of Fe ₂ O ₃ to 50% by mass or less according to the ash composition analysis, or suppressing the carbonization temperature to about 1100°C.

Moreover, it is preferable to add formic acid to the coal before filling the carbonization chamber 101 of the coke oven 10 with coal. When formic acid is added, the formic acid is decomposed into carbon dioxide and hydrogen when the coal is carbonized in the carbonization chamber 101. Carbon dioxide can contribute to the calorie increase of COG by reacting and being reduced to carbon monoxide. Furthermore, as the amount of hydrogen increases, the reverse shift reaction of the above formula 105 progresses more easily, so that the reduction efficiency of carbon dioxide can be further improved.

The amount of formic acid to be added is not particularly limited, and may be any amount. For example, when the amount of coal to be filled in one furnace of the carbonization chamber 101 is about 30 tons, about 27.6 tons of coal that has been dried in advance with DAPS from 10% to 2% by weight, is mixed with about 2% of formic anhydride. .4t may be added (ie, the same amount of formic acid as the water removed by drying may be added). In this case, the carbon dioxide produced by the decomposition of formic acid is 2.3t-CO ₂ , and the molar ratio (CO ₂ / C)=0.18 carbon dioxide.

If the formic acid used is anhydrous, it can be efficiently incorporated into pre-dried coal. Furthermore, in Japan, if the formic acid content in an aqueous solution is less than 90%, it does not fall under the category of a deleterious substance as stipulated 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 fall under the category of hazardous materials stipulated in the Fire Service Act, so the concentration of the formic acid aqueous solution should be changed depending on the conditions of the factory, etc. where it is used. is also possible. However, if the concentration of formic acid in the aqueous solution is too low, the amount of water will become too large, and water will have to be added to the previously dried coal, resulting in a waste of energy.

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

Hereinafter, the present invention will be explained in more detail with reference to examples. The conditions in the examples are examples of conditions adopted to confirm the feasibility and effects of the present invention, and the present invention is based on these conditions. The examples are not limited. The present invention can adopt various conditions as long as the purpose of the present invention is achieved without departing from the gist of the present invention.

(Example 1)
Carbon dioxide was reduced to increase the calorie content of COG using a manufacturing facility that combines a coke oven and a catalytic furnace as shown in FIGS. 1 and 2. Approximately 30 tons of coal was filled into the carbonization chamber of a coke oven, and carbonization was started by heating at approximately 1100° C. from combustion chambers on both sides of the coke oven. Analysis of the ash content in the coal revealed that, regarding alkaline earth metals, the concentrations of CaO and MgO were 7.2% by mass and 3.1% by mass, respectively, and the concentration of Fe ₂ O ₃ was 8.5% by mass. there were. COG was generated by carbonization in an amount of about 436 Nm ³ /h, and the gas composition (in volume %) was about 50% H ₂ , about 30% CH ₄ , and the balance was N ₂ . Additionally, tar was generated at a rate of 136 kg/h. The gas calorie at this time was 7024 MJ/h on a dry basis.

Here, carbon dioxide is controlled to be supplied from the furnace lid on the exhaust port side at a rate of 158 Nm ³ /h so that the molar ratio (CO ₂ /C) to CH ₄ and carbon contained in the tar is 0.5. I did it. At this time, the temperature in the top space of the coke oven was about 950°C. Furthermore, the high-temperature reformed COG in the coke oven containing unreacted carbon dioxide discharged from the coke oven is supplied to a catalytic furnace heated to about 800°C, and space velocity (SV) = 500 h ^-1 , normal A hydrocarbon CO ₂ reforming reaction 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 using the following equation 201.

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

Furthermore, the ratio between the calorie of the COG after the reaction and the calorie before and after the reaction was calculated from the gas composition and gas volume after the reaction. The conversion rate of _CO2 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 31% _H2 , 19% _CH4 , 21% CO, _CO2 16%, the balance was N ₂ , and the volume was 1.54 times that of COG before reaction.

Furthermore, the CO ₂ conversion rate is 50% in the catalytic furnace, and the composition (volume %) of the catalytically reformed COG at the outlet of the catalytic furnace is 34% H ₂ , 15% CH ₄ , 33% CO , 7% CO ₂ , The remainder was _N2 , and the volume was 1.73 times that of COG before reaction.

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

(Example 2)
In Example 1, CO ₂ was controlled to be supplied from the furnace lid at a rate of 316 Nm ³ /h so that the molar ratio (CO ₂ /C) to CH ₄ and carbon contained in tar was 1.0. The same procedure as in Example 1 was carried out except for the following.

The conversion rate of _CO2 in the coke oven is 40%, and the gas composition of the reformed COG in the coke oven at the outlet of the coke oven is 25% _H2 , 15% _CH4 , 24% CO, ₂₆ % CO2, The remainder was _N2 , and the volume was 1.98 times that of COG before reaction. Furthermore, the CO ₂ conversion rate in the catalytic furnace is 50%, and the composition of the catalytically reformed COG at the outlet of the catalytic furnace is 26% H ₂ , 12% CH ₄ , 43% CO , 11% CO ₂ , and the balance is N _{2 .} The volume was 2.31 times that of COG before reaction. As a result, the calorie of COG after the reaction was 12,416 MJ/h on a dry basis. Here, when we calculated the total amount of energy required to heat CO ₂ at room temperature to a coke oven top space temperature of 950°C and to compensate for the endothermic reactions inside the coke oven and the catalyst furnace, we found that it was 2260 MJ/ It became h. Therefore, it was found that the net calorie of COG after reaction was 10156 MJ/h, which was 1.45 times that of COG before reaction. In this way, it has been found that by combining a coke oven and a catalytic furnace and setting the molar ratio (CO ₂ /C) to 1, it is possible to increase the calorie content of COG.

(Example 3)
In Example 1, CO ₂ was controlled to be supplied from the furnace lid at 474 Nm ³ /h so that the molar ratio (CO ₂ /C) to CH ₄ and carbon contained in tar was 1.5. The same procedure as in Example 1 was carried out except for the following.

The conversion rate of _CO2 in the coke oven is 25%, and the composition of the reformed COG in the coke oven at the outlet of the coke oven is 20% _H2 , 12% _CH4 , 18.5% CO, and 40.9 _{% CO2.} %, the remainder was _N2 , and the volume was 2.33 times that of COG before reaction. Furthermore, in the catalytic furnace, the CO ₂ conversion rate is 50%, and the composition of the catalytically reformed COG at the outlet of the catalytic furnace is 21.2% H ₂ , 8.5% CH ₄ , 42.4% CO ₂ 20.3%, the remainder was N ₂ , and the volume was 2.6 times that of COG before reaction. As a result, the calorie of COG after reaction was 12076 MJ/h on a dry basis. Here, when we calculated the total amount of energy required to heat CO ₂ at room temperature to a coke oven top space temperature of 950°C and to compensate for the endothermic reactions inside the coke oven and catalyst furnace, we found that it was 3036 MJ/ It became h. Therefore, it was found that the net calorie of COG after reaction was 9040 MJ/h, which was 1.29 times that of COG before reaction. In this way, it was found that by combining a coke oven and a catalytic furnace and setting the molar ratio (CO ₂ /C) to 1.5, it was possible to increase the calorie content of COG.

(Example 4)
In Example 1, CO ₂ was controlled to be supplied from the furnace lid at a rate of 632 Nm ³ /h so that the molar ratio (CO ₂ /C) to CH ₄ and carbon contained in tar was 2.0. The same procedure as in Example 1 was carried out except for the following.

The conversion rate of _CO2 in the coke oven is 10%, and the composition of the reformed COG in the coke oven at the coke oven outlet is 18% _H2 , 11% _CH4 , 10% CO, 54% _CO2 , and the balance. N ₂ and the volume was 2.68 times that of COG before reaction. Furthermore, in the catalytic furnace, the CO ₂ conversion rate is 50%, and the composition of the catalytically reformed COG at the outlet of the catalytic furnace is 19% H ₂ , 7% CH ₄ , 42% CO , 26% CO ₂ , and the balance N ₂ The volume was 2.82 times that of COG before reaction. As a result, the calorie of COG after reaction was 12076 MJ/h on a dry basis. Here, when we calculated the total amount of energy required to heat _CO2 at room temperature to a coke oven top space temperature of 950°C and to compensate for the endothermic reactions inside the coke oven and the catalyst furnace, we found that it was 3815 MJ/ It became h. Therefore, it was found that the net calorie of COG after reaction was 8261 MJ/h, which was 1.18 times that of COG before reaction. In this way, it was found that by combining a coke oven and a catalytic furnace and setting the molar ratio (CO ₂ /C) to 2.0, it was possible to increase the calorie content of COG.

(Example 5)
Example 1 was carried out in the same manner as in Example 1, except that the amount of catalyst 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, the CO ₂ conversion rate in the catalytic furnace was 50 ^% , and the composition of the catalytically reformed COG at the outlet of the catalytic furnace 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 reaction. Further, it was found that the net calorie of COG after reaction was 8231 MJ/h, which was 1.17 times that of COG before reaction. Since the reactivity remains the same even when the space velocity SV is set to 1000 h ^-1 , the equipment can be made more compact, leading to a reduction in equipment costs.

(Comparative example 1)
Example 1 was carried out in the same manner as in Example 1, except that a manufacturing facility having only a coke oven and no catalyst furnace as shown in FIG. 2 was used.

As a result, the calorie of COG after reaction was 8624 MJ/h on a dry basis. Here, the total amount of energy required to heat CO ₂ at room temperature to a coke oven top space temperature of 950° C. and to compensate for the endothermic reaction within the coke oven was calculated to be 780 MJ/h. Therefore, it was found that the net calorie of COG after reaction was 7844 MJ/h, which was 1.12 times that of COG before reaction. From these results, in a production facility consisting only of a coke oven without a catalytic furnace, even if carbon dioxide is supplied to the coke oven at a molar ratio (CO ₂ /C) = 0.5, COG It turns out that it is almost impossible to increase the amount of calories.

(Comparative example 2)
In Example 1, CO ₂ was not supplied from the lid of the coke oven, and as shown in FIG. 2, carbon dioxide was supplied only from the front of the catalytic furnace at a molar ratio (CO ₂ /C) of 0.5. , 158 Nm ³ /h except that the supply was controlled in the same manner as in Example 1.

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

(Comparative example 3)
Comparative Example 2 was carried out in the same manner as Comparative Example 2, except that carbon dioxide was controlled to be supplied at 316 Nm ³ /h from before the catalyst furnace so that the molar ratio (CO ₂ /C) = 1. .

As a result, the CO ₂ conversion rate was 50% in the catalytic furnace, and the composition of the catalytically reformed COG at the outlet of the catalytic furnace was: 25.0% H ₂ , 13.8% CH ₄ , 33.4% CO ₂ 18.5%, the balance was N ₂ , and the volume was 1.68 times that of COG before reaction. As a result, the calorie of COG after reaction was 8664 MJ/h on a dry basis. Here, when the total amount of energy required to heat CO ₂ at room temperature to the catalyst furnace temperature of 800° C. and the energy required to compensate for the endothermic reaction within the catalyst furnace was calculated, it was 1669 MJ/h. Therefore, it was found that the net calorie of COG after reaction was 6995 MJ/h, which was 1.00 times that of COG before reaction. These results show that it is not possible to increase the calorie content of COG by simply supplying carbon dioxide to the catalytic furnace at a molar ratio (CO ₂ /C) of 1.

(Example 6)
Example 1 was carried out in the same manner as in Example 1, except that 158 Nm ³ /h of carbon dioxide, which corresponds to a molar ratio (CO ₂ /C) = 0.5, was further controlled to be supplied from before the catalyst furnace. carried out.

As a result, the CO ₂ conversion rate in the catalytic furnace was 50%, and the composition of the catalytically reformed COG at the outlet of the catalytic furnace was: 23.9% H ₂ , 9.7% CH ₄ , 45.1% CO ₂ 13.0%, the balance was N ₂ , and the volume was 2.43 times that of COG before reaction. As a result, the calorie of COG after reaction was 12424 MJ/h on a dry basis. Here, the energy required to heat _CO2 at room temperature to the coke oven top space temperature of 950 °C and the catalyst furnace temperature of 800 °C, as well as the energy required to compensate for the endothermic reactions in the coke oven and the catalyst furnace, are The total amount was calculated to be 2226 MJ/h. Therefore, it was found that the net calorie of COG after reaction was 10198 MJ/h, which was 1.45 times that of COG before reaction. In this way, a coke oven and a catalytic furnace are combined, and the molar ratio (CO ₂ /C) is 0.5 in front of the coke oven, and the molar ratio (CO ₂ /C) is 0.5 in front of the catalytic furnace. It was found that the calorie content of COG could be further increased by supplying carbon dioxide.

(Example 7)
Example 2 was carried out in the same manner as in Example 2, except that 158 Nm ³ /h of carbon dioxide, which corresponds to a molar ratio (CO ₂ /C) = 0.5, was further controlled to be supplied from before the catalyst furnace. did.

As a result, the CO ₂ conversion rate in the catalytic furnace was 50%, and the composition of the catalytically reformed COG at the outlet of the catalytic furnace was 20.9% H ₂ , 7.2% CH ₄ , 49.4% CO ₂ 15.6%, the balance was N ₂ , and the volume was 2.88 times that of COG before reaction. As a result, the calorie of COG after the reaction was 13,872 MJ/h on a dry basis. Here, the energy required to heat _CO2 at room temperature to the coke oven top space temperature of 950 °C and the catalyst furnace temperature of 800 °C, as well as the energy required to compensate for the endothermic reactions in the coke oven and the catalyst furnace, are The total amount was calculated to be 2831 MJ/h. Therefore, it was found that the net calorie of COG after reaction was 11041 MJ/h, which was 1.57 times that of COG before reaction. As a result, a coke oven and a catalytic furnace are combined, and the molar ratio (CO ₂ /C) is 1.0 in front of the coke oven, and the molar ratio (CO ₂ /C) is 0.5 in front of the catalytic furnace. It was found that the calorie content of COG could 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 catalytic furnace was installed at a location approximately 20 m away from the coke oven.

Although the catalytic furnace is 20m away from the coke oven and the piping is insulated with heat insulating material, the temperature of the reformed COG in the coke oven has dropped from 800°C to 500°C, so energy is required to raise the temperature in the catalytic furnace to the reaction temperature. additionally required. Here, the energy required to heat _CO2 at room temperature to a coke oven top space temperature of 950°C, the energy required to compensate for the endothermic reactions in the coke oven and the catalytic furnace, and the reforming in the coke oven at 500°C. The total amount of energy required to heat COG to the catalyst furnace temperature of 800° C. was calculated to be 2732 MJ/h. Therefore, it was found that the net calorie of COG after reaction was 9684 MJ/h, which was 1.38 times that of COG before reaction. From this, it was found that even if the catalytic furnace is separated from the coke oven to some extent, there is no significant effect on the increase in calories of reformed COG.

(Example 9)
In Example 1, the process was carried out in the same manner as in Example 1, except that about 30 tons of coal, which had been impregnated with about 2.4 tons of formic anhydride against about 27.6 tons of coal pre-dried with DAPS, was charged into the carbonization chamber of the coke oven. carried out.

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

(Example 10)
Example 1 was carried out in the same manner as in Example 1, except that the amount of catalyst in the catalytic reaction step was increased five times and the space velocity SV in the catalytic furnace was set to 100 h ^-1 .

As a result, compared to the result at 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 36% H ₂ , CH ₄ 13%, CO 35%, CO ₂ 4%, balance N ₂ , and the volume was 1.77 times that of COG before reaction. Further, it was found that the net calorie of COG after reaction was 8278 MJ/h, which was 1.18 times that of COG before reaction. When the space velocity SV is set to 100 h ^-1 , the reactivity improves, so the calorie content of COG can be increased. However, since the amount of catalyst is five times as large, the size of the catalytic reactor is also five times as large, resulting in an increase in equipment cost.

(Example 11)
Example 1 was carried out in the same manner as in Example 1, except that the amount of catalyst in the catalytic reaction step was reduced to 1/5 and the space velocity SV in the catalytic furnace was set to 2500 h ^-1 .

As a result, compared to 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 catalytically reformed COG at the outlet of the catalytic furnace was 33% H ₂ , CH ₄ 17%, CO 27%, CO ₂ 11%, balance N ₂ , and the volume was 1.73 times that of COG before reaction. Further, it was found that the net calorie of COG after reaction was 8078 MJ/h, which was 1.15 times that of COG before reaction. When the space velocity SV is set to 2500 h ^-1 , the reactivity decreases, so the effect of increasing the calorie content of COG is small, but since the amount of catalyst is 1/5, the equipment can be made compact and the equipment cost can be reduced significantly. This led to a reduction in

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

As a result, the CO ₂ conversion rate progressed at 10% in the coke oven. At this time, the total amount of energy required to heat CO ₂ at room temperature to the coke oven top space temperature of 950° C. and to compensate for the endothermic reaction in the catalyst furnace was calculated to be 1461 MJ/h. It was found that the net calorie of COG after reaction was 8171 MJ/h, which was 1.16 times that of COG before reaction. From this, even if the concentration of CaO and MgO and the concentration of Fe ₂ O ₃ are low in the ash composition of the coal used, if the reactivity in the coke oven progresses to a certain level, the calorie content of COG can be increased. I found out that it can be done.

(Example 13)
In Example 1, in the ash composition analysis of the coal filled in the carbonization chamber of a coke oven, the concentrations of CaO and MgO with respect to alkaline earth metals were 1.5% by mass and 0.4% by mass, respectively. The same procedure as in Example 1 was conducted 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 required to heat CO ₂ at room temperature to a coke oven top space temperature of 950° C. and to compensate for the endothermic reaction in the catalyst furnace was calculated to be 1594 MJ/h. It was found that the net calorie of COG after reaction was 8406 MJ/h, which was 1.20 times that of COG before reaction. From this, it was found that when the concentration of Fe ₂ O ₃ in the ash composition of the coal used is high, the reactivity in the coke oven is high and the calorie content of COG can be increased.

(Example 14)
In Example 1, in the ash composition analysis of the coal filled in the carbonization chamber of a coke oven, the concentrations of CaO and MgO are respectively 12% by mass and 3.5% by mass with respect to alkaline earth metals, The same procedure as in Example 1 was carried out 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 required to heat CO ₂ at room temperature to a coke oven top space temperature of 950° C. and to compensate for the endothermic reaction in the catalyst furnace was calculated to be 1594 MJ/h. It was found that the net calorie of COG after reaction was 8425 MJ/h, which was 1.20 times that of COG before reaction. From this, it was found that when the concentration of CaO is high in the ash composition of the coal used, the reactivity in the coke oven is high and the calorie content of COG can be increased.

(Example 15)
In Example 1, a pre-prepared aqueous solution of Ca(OH) ₂ with a concentration of 15% was sprinkled on coal, and about 30 tons of the coal, whose moisture content was adjusted with CMC, was filled into the carbonization chamber of a coke oven. The temperature was lowered to about 1000°C and carbonization was started. Analysis of the ash content in the coal revealed that, regarding alkaline earth metals, the concentrations of CaO and MgO were 43.8% by mass and 1.2% by mass, respectively, and the concentration of Fe ₂ O ₃ was 3.5% by mass. The same procedure as in Example 1 was carried out except that .

At this time, the temperature in 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 required to heat CO ₂ at room temperature to a coke oven top space temperature of 850° C. and to compensate for the endothermic reaction in the catalyst furnace was calculated to be 1440 MJ/h. It was found that the net calorie of COG after reaction was 8513 MJ/h, which was 1.21 times that of COG before reaction. From this, by adding Ca component in advance to the ash composition of the coal used, the reaction in the coke oven can proceed at a lower temperature, and additional energy can be suppressed, so the calories of COG can be reduced. I found out that I can increase the amount even more.

(Example 16)
In Example 1, about 700 kg of CaCO ₃ was filled on top of the coal packed in the carbonization chamber of a coke oven, so that the height of the limestone layer was about 100 mm, and the carbonization chamber from the combustion chambers on both sides of the coke oven was The same procedure as in Example 1 was carried out, except that the heating temperature was lowered to about 1000° C. and carbonization was started.

At this time, the temperature in 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 CO ₂ at room temperature to a coke oven top space temperature of 850° C. and to compensate for the endothermic reaction in the catalyst furnace was calculated to be 1554 MJ/h. It was found that the net calorie of COG after reaction was 8504 MJ/h, which was 1.21 times that of COG before reaction. This suggests that the presence of a Ca-based compound in the area where _CO2 comes into contact with COG or tar allows the reaction in the coke oven to proceed at a lower temperature, reducing the need for additional energy. It was found that the calorie content of COG could be further increased.

The results obtained in the Examples and Comparative Examples shown above are summarized in Table 1 below and are shown as graphs in FIGS. 4 and 5. Note that 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 a large amount of carbon dioxide at room temperature and further increase the calorie content of COG. It became.

Although 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 clear that a person with ordinary knowledge in the technical field to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea stated in the claims. It is understood that these also naturally fall within the technical scope of the present invention.

1 Coke manufacturing equipment 10 Coke oven 20 Catalytic furnace 30, 40 Control valve 50 Control device 101 Carbonization chamber 103 Coal insertion port 105 Furnace top space 107 Discharge port 109 Furnace lid 111 Reforming COG in coke oven
113 Rising pipe 115 Carbon dioxide supply port 117 Dry main 119 Catalytic reforming COG

Claims (10)

A coke oven reaction step of supplying carbon dioxide to a coking chamber filled with coal in a coke oven, and converting the carbon dioxide into carbon monoxide by reacting with a carbon component and hydrogen present in the coking chamber;
Coke oven gas containing unreacted carbon dioxide supplied to the carbonization chamber is supplied to a catalyst furnace provided with a catalyst, and the unreacted carbon dioxide is reformed into carbon monoxide. Quality process and
including;
The carbonization chamber is provided with an outlet for discharging coke produced from the coal, and a riser pipe for discharging coke oven gas containing unreacted carbon dioxide,
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 riser pipe ,
A method for reducing carbon dioxide, in which the coal to be filled into the carbonization chamber is made to contain formic acid prior to charging . A coke oven reaction step of supplying carbon dioxide to a coking chamber filled with coal in a coke oven, and converting the carbon dioxide into carbon monoxide by reacting with a carbon component and hydrogen present in the coking chamber;
Coke oven gas containing unreacted carbon dioxide supplied to the carbonization chamber is supplied to a catalyst furnace provided with a catalyst, and the unreacted carbon dioxide is reformed into carbon monoxide. Quality process and
including;
The carbonization chamber is provided with an outlet for discharging coke produced from the coal, and a riser pipe for discharging coke oven gas containing unreacted carbon dioxide,
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 riser pipe,
A method for reducing carbon dioxide, in which the coal to be filled into the carbonization chamber is made to contain a Ca component prior to charging. A coke oven reaction step of supplying carbon dioxide to a coking chamber filled with coal in a coke oven, and converting the carbon dioxide into carbon monoxide by reacting with a carbon component and hydrogen present in the coking chamber;
Coke oven gas containing unreacted carbon dioxide supplied to the carbonization chamber is supplied to a catalyst furnace provided with a catalyst, and the unreacted carbon dioxide is reformed into carbon monoxide. Quality process and
including;
The carbonization chamber is provided with an outlet for discharging coke produced from the coal, and a riser pipe for discharging coke oven gas containing unreacted carbon dioxide,
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 riser pipe,
A method for reducing carbon dioxide, comprising: filling the carbonization chamber with the coal, and then installing a Ca-containing substance on the surface layer of the filled coal. According to any one of claims 1 to 3, the carbon dioxide supplied to the carbonization chamber has a molar ratio of more than 0.2 and less than or equal to 2.0 in terms of a molar ratio to the carbon component in the coke oven gas. method for reducing carbon dioxide. The carbon dioxide according to any one of claims 1 to 4 , wherein the coke oven gas containing unreacted carbon dioxide supplied to the catalytic furnace has a space velocity of 250 h ^-1 or more and 2000 h ^-1 or less. Carbon reduction method. The carbon dioxide according to any one of claims 1 to 5 , wherein in the catalytic reforming step, carbon dioxide is further supplied to the catalytic furnace together with coke oven gas containing unreacted carbon dioxide. Reduction method. 7. The method for reducing carbon dioxide according to claim 6 , wherein the carbon dioxide supplied to the catalytic furnace has a molar ratio of 0.1 to 1.0 with respect to the carbon component in the coke oven gas. The method for reducing carbon dioxide according to any one of claims 1 to 7 , wherein the carbon dioxide is supplied to a furnace top space of the carbonization chamber. Claims 1 to 3, wherein when the ash of the coal filled in the carbonization chamber is measured by X-ray fluorescence analysis, the concentration of CaO and MgO in the obtained ash composition is 3% by mass or more in total. 8. The method for reducing carbon dioxide according to any one of 8 . Claims 1 to 9, wherein when the ash of the coal filled in the carbonization chamber is measured by X-ray fluorescence analysis, the concentration of Fe ₂ O ₃ in the obtained ash composition is 5% by mass or more . The method for reducing carbon dioxide according to any one of the above.

Images