WO2022201828A1

WO2022201828A1 - Carburizing gas supply system and carburizing system

Info

Publication number: WO2022201828A1
Application number: PCT/JP2022/002544
Authority: WO
Inventors: 章軍司; 晃平吉川; 昌俊杉政
Original assignee: 株式会社日立製作所
Priority date: 2021-03-25
Filing date: 2022-01-25
Publication date: 2022-09-29
Also published as: JP2022149184A

Abstract

The main purpose of the present invention is to provide a carburizing gas supply system with which it is possible to reduce the carbon dioxide emission amount, to reduce the usage amount of new carburizing gas, and to supply an optimum gas composition in accordance with the state in a furnace.　This carburizing gas supply system comprises: a gas discharge unit that discharges exhaust gas from a carburizing furnace; a first flow rate measurement unit that measures the flow rate of the exhaust gas; a first concentration measurement unit that measures the concentration of components of the exhaust gas; a first supply unit that supplies carbon dioxide to the exhaust gas; a control unit that controls the supply amount of the carbon dioxide on the basis of the flow rate of the exhaust gas and the concentration of the components; a carbon dioxide conversion unit that generates hydrocarbon or carbon monoxide from the carbon dioxide, and removes water or oxygen; and a carburizing gas supply unit that supplies, to the carburizing furnace, regenerated carburizing gas containing components derived from the generated hydrocarbon or carbon monoxide.

Description

Carburizing gas supply system and carburizing system

The present invention relates to a carburizing gas supply system that supplies a carburizing gas to a carburizing furnace that performs carburizing, and a carburizing system that uses the carburizing gas supply system.

In order to increase the wear resistance of steel parts, carburizing treatment is performed to diffuse carbon from the surface of the steel material. In the carburizing process, a gas called RX gas containing hydrogen (H ₂ ), carbon monoxide (CO), and nitrogen (N ₂ ) as main components is produced by reacting a hydrocarbon such as methane (CH ₄ ) with air. is generated and supplied to the carburizing furnace as a base gas. Furthermore, the carburizing process is controlled by adjusting the carbon potential (CP) in the carburizing furnace by adding hydrocarbons called enriched gas to the RX gas as needed. The carbon potential can be estimated from the composition and temperature of the carburizing gas, which is the RX gas or the RX gas to which the enriched gas is added, and can be controlled by the supply flow rate of the enriched gas.

In the carburizing process, carburizing gas with controlled carbon potential is continuously supplied to the carburizing furnace in order to maintain the atmosphere in the carburizing furnace. However, most of the carbon monoxide and hydrogen contained in the carburizing gas are discharged to the outside of the carburizing furnace without reacting, and are exhausted after being burned. Therefore, there is a problem of consuming a lot of fuel. On the other hand, effective utilization of the exhaust gas discharged from the carburizing furnace has been proposed.

For example, in Patent Document 1, exhaust gas discharged from a carburizing furnace is recovered, water vapor (H ₂ O) and carbon dioxide (CO ₂ ) are removed from the exhaust gas, and the exhaust gas after removing water vapor and carbon dioxide is disclosed. A gas supply system that recycles is described.

JP 2017-226893 A

However, in the gas supply system described in Patent Document 1, since there is no description about the treatment of carbon dioxide removed from the exhaust gas in Patent Document 1, carbon dioxide is discharged as it is and is released into the atmosphere as a greenhouse gas. . In addition, since nitrogen is not removed from the exhaust gas and stays in the gas supply system, the concentration and flow rate of nitrogen in the recycled gas increase over time. As a result, when the RX gas and the recycle gas are mixed, the concentration of carbon monoxide and carbon dioxide decreases, which may decrease the carburization rate.

The present invention has been made in view of the above problems, and can reduce carbon dioxide emissions, reduce the amount of new carburizing gas used, and supply an optimum gas composition according to the conditions inside the furnace. A main object of the present invention is to provide a carburizing gas supply system and a carburizing system.

In order to solve the above-described problems, the carburizing gas supply system of the present invention provides a carburizing gas supply system that supplies a carburizing gas to a carburizing furnace that performs carburizing treatment, comprising: , a first flow rate measurement unit for measuring the flow rate of the exhaust gas, a first concentration measurement unit for measuring the concentration of the components of the exhaust gas, a first supply unit for supplying carbon dioxide to the exhaust gas, and the flow rate of the exhaust gas. and a control unit that controls the supply amount of the carbon dioxide based on the concentrations of the above components, a carbon dioxide conversion unit that generates hydrocarbons or carbon monoxide from carbon dioxide and removes water or oxygen, and the carbon dioxide a carburizing gas supply unit for supplying the regenerated carburizing gas containing the hydrocarbons or carbon monoxide generated in the converting unit to the carburizing furnace.

A carburizing system according to the present invention includes the carburizing gas supply system and a carburizing furnace for carburizing.
This specification includes the disclosure content of Japanese Patent Application No. 2021-051216, which is the basis of priority of this application.

According to the present invention, the amount of carbon dioxide emissions can be reduced, the amount of new carburizing gas used can be reduced, and the optimum gas composition can be supplied according to the conditions inside the furnace.

The problems, configurations, and effects of the present invention other than those described above will be clarified by the following description of the mode for carrying out the invention.

1 is a diagram showing an outline of a carburizing gas supply system and a carburizing system according to Embodiment 1. FIG. 1 shows an outline of a carburizing gas supply system and a carburizing system according to a modification of the first embodiment, in which the carburizing gas supply system measures the flow rate of the gas supplied to the carburizing furnace and the concentration of the components of the gas; FIG. 4 is a diagram showing; FIG. 5 is a diagram showing an outline of a carburizing gas supply system and a carburizing system according to Embodiment 2; FIG. 10 is a diagram showing an outline of a carburizing gas supply system and a carburizing system according to Embodiment 3; FIG. 10 is a diagram showing an outline of a carburizing gas supply system and a carburizing system according to Embodiment 4; 1 is a schematic diagram of a conventional carburizing gas supply system and a carburizing system; FIG.

Hereinafter, embodiments according to the present invention will be described using drawings and the like. The following description shows specific examples of the content of the present invention, and the present invention is not limited to these descriptions, and can be implemented by those skilled in the art within the scope of the technical ideas disclosed herein. Various changes and modifications are possible. In addition, in all the drawings for explaining the present invention, parts having the same functions are denoted by the same reference numerals, and repeated explanations thereof may be omitted.

"~" described in this specification is used to mean that the numerical values before and after it are included as lower and upper limits. In the numerical ranges described stepwise in this specification, the upper limit value or lower limit value described in one numerical range may be replaced with the upper limit value or lower limit value described in another stepwise manner. The upper or lower limits of the numerical ranges described herein may be replaced with the values shown in the examples.

When selecting a material from the material group exemplified below, the material may be selected singly or in combination as long as it is not inconsistent with the content disclosed in this specification. , materials other than those exemplified below may be selected as long as they are consistent with what is disclosed herein.

(Embodiment 1)
A carburizing gas supply system and a carburizing system according to Embodiment 1 will be described. FIG. 1 is a schematic diagram of a carburizing gas supply system and a carburizing system according to Embodiment 1. FIG. FIG. 6 is a schematic diagram of a conventional carburizing system.

A conventional carburizing system 100 includes an RX gas generator 1, an enriched gas supply unit 2, a carburizing furnace 3, a combustion facility 4, and a gas flow path 20, as shown in FIG. In contrast, the carburizing system 100 according to the first embodiment includes an RX gas generator 1, an enriched gas supply unit 2, a carburizing furnace 3, a carburizing gas supply system 50, a combustion facility 4, a gas flow path 20.

The RX gas generator 1 reacts a hydrocarbon such as methane (CH ₄ ) with air to produce RX gas, which is mainly composed of hydrogen (H ₂ ), carbon monoxide (CO), and nitrogen (N ₂ ). and is supplied to the carburizing furnace 3 through the gas flow path 20 and the supply port 3a. The enriched gas supply unit 2 adds a hydrocarbon called enriched gas to the RX gas as necessary, and supplies the RX gas to the carburizing furnace 3 via the supply port 3a via the gas flow path 20 . Although the composition of the RX gas is not particularly limited, for example, it contains 40% by volume of hydrogen, 20% by volume of carbon monoxide, and 40% by volume of nitrogen, in addition to some carbon dioxide (CO ₂ ) and water vapor (H ₂ O). Examples of the enriched gas include, but are not limited to, methane (CH ₄ ), propane (C ₃ H ₈ ), and the like.

If it is necessary to add the enriched gas to the RX gas, it is necessary to control the carburizing process by adjusting the carbon potential (CP) in the carburizing furnace 3 by adding the enriched gas to the RX gas. is the case.

To the carburizing furnace 3, RX gas or a gas obtained by adding enriched gas to RX gas is supplied as a new carburizing gas. The carburizing furnace 3 uses a new carburizing gas to carburize the steel material placed in the carburizing furnace 3 . Specifically, in the carburizing treatment, carbon is diffused from the surface of the steel material. After the new carburizing gas has been used for the carburizing process, the gas is discharged as exhaust gas from the carburizing furnace 3 to the gas flow path 20 through the discharge port 3b. Exhaust gas contains carbon dioxide and water vapor (water) in addition to hydrogen, carbon monoxide, and nitrogen. Although the composition of the exhaust gas is not particularly limited, it contains, for example, a total of 55 to 59% by volume of hydrogen and carbon monoxide, a total of 1 to 4% by volume of carbon dioxide and water vapor, and 40 to 43% by volume of nitrogen.

A carburizing gas supply system 50 according to the first embodiment is a carburizing gas supply system that supplies a carburizing gas to a carburizing furnace 3, and includes a gas discharge section 30, a first flow rate measuring section 5, and a first concentration measuring section. 6, a first supply unit 8, a second supply unit 9, a third supply unit 15, a control unit 7, a carbon dioxide conversion unit 10, a pressure increasing unit 13, a reforming reaction unit 14, and for carburizing A gas supply unit 40 and a gas flow path 20 are provided.

The gas discharge part 30 is composed of an outlet 3b of the carburizing furnace 3 and a gas flow path 20 connected to the outlet 3b, and discharges exhaust gas from the carburizing furnace 3 to the gas flow path 20 through the outlet 3b. The gas flow path 20 is branched downstream of the gas discharge section 30 and connected to the combustion equipment 4 and the first flow rate measurement section 5 respectively. In the carburizing gas supply system 50 , exhaust gas discharged from the carburizing furnace 3 is introduced into the first flow rate measuring section 5 through the gas flow path 20 . All of the exhaust gas discharged from the carburizing furnace 3 can be introduced into the first flow rate measuring unit 5, or only a part of it can be introduced into the first flow rate measuring unit 5. From the viewpoint of reduction, it is preferable to introduce all of them into the first flow rate measuring section 5 . The rest of the exhaust gas that is not introduced into the first flow rate measuring unit 5 is introduced into the combustion facility 4 via the gas flow path 20, and discharged outside after detoxification.

The first flow rate measurement unit 5 measures the flow rate of the exhaust gas introduced into the first flow rate measurement unit 5 . After the flow rate measurement, the exhaust gas is introduced into the first concentration measuring section 6 via the gas flow path 20 . The first concentration measuring section 6 measures the concentrations of the components of the exhaust gas introduced into the first concentration measuring section 6 . The first concentration measuring unit 6 is not particularly limited as long as it measures the concentration of the exhaust gas component that enables the estimation of the carbon consumption, which will be described later. The first concentration measuring unit 6 may measure the concentration of some or all of the components of the exhaust gas. For example, it may be one that measures the concentration of at least carbon dioxide among the components of the exhaust gas.

Here, FIG. 2 shows a carburizing gas supply system and a carburizing system according to a modified example of the first embodiment, in which the flow rate of the gas supplied to the carburizing furnace by the carburizing gas supply system and the concentration of the components of the gas are measured. It is a figure which shows the outline of what was made to carry out.

The carburizing gas supply system 50 according to the modification of the first embodiment further includes a second flow rate measuring section 21 and a second concentration measuring section 22 in addition to the configuration of the carburizing gas supply system 50 shown in FIG. . The second flow rate measuring unit 21 measures the flow rate of the regeneration carburizing gas supplied to the carburizing furnace 3 . The second concentration measuring unit 22 measures the concentration of the components of the regeneration carburizing gas supplied to the carburizing furnace 3 . As in the modification of Embodiment 1, in addition to the first flow rate measurement unit 5 and the first concentration measurement unit 6 measuring the flow rate of the exhaust gas and the concentration of the components of the exhaust gas, the second flow rate measurement unit 21 and the second 2 By measuring the flow rate of the regenerating carburizing gas and the concentration of the components of the regenerating carburizing gas by the concentration measuring unit 22, it becomes easier to estimate the amount of carbon consumed in the carburizing furnace, and the gas to be supplied to the carburizing furnace can be easily estimated. It becomes even easier to supply the optimum gas composition.

The first supply unit 8 supplies carbon dioxide to the exhaust gas on the downstream side of the first concentration measurement unit 6 in the gas flow path 20 . The second supply unit 9 supplies hydrogen to the exhaust gas on the downstream side of the first concentration measurement unit 6 in the gas flow path 20 .

The control unit 7 determines the supply amount of carbon dioxide supplied to the exhaust gas by the first supply unit 8 based on the flow rate and component concentrations of the exhaust gas measured by the first flow rate measurement unit 5 and the first concentration measurement unit 6, and the amount of hydrogen supplied to the exhaust gas by the second supply unit 9 is controlled. Here, a method for controlling the amount of carbon dioxide supplied and the amount of hydrogen supplied will be described in detail.

In the carburizing process in the carburizing furnace 3, the amount of carbon added to the steel material from the new carburizing gas and consumed from the new carburizing gas (hereinafter sometimes abbreviated as "consumed carbon amount") is determined by the flow rate and the composition of the exhaust gas. can be estimated from the concentration of Specifically, as a method for estimating the amount of carbon consumed, for example, carbon is added to the steel material by the reaction shown in formula (1) in the carburizing process, so the amount of carbon consumed is the same amount of substance as the increase in carbon dioxide Based on the premise that it will be After obtaining the amount of increase, the amount of carbon consumption is estimated from the amount of increase in the flow rate of the exhaust gas and the carbon dioxide concentration. Note that even when carbon dioxide reacts according to equation (5) described later, the amount of carbon consumed can be estimated by measuring the water vapor concentration.

2CO→C+CO ₂ (1)

Therefore, in this control method, after estimating the amount of carbon consumed, the flow rate of carbon dioxide supplied to the exhaust gas by the first supply unit 8 is adjusted so that the same amount of carbon as the amount of carbon consumed is supplied to the exhaust gas. Control. Furthermore, based on the flow rate and component concentration of the exhaust gas, the flow rate of carbon dioxide contained in the exhaust gas is calculated, and the flow rate of carbon dioxide contained in the exhaust gas and the amount of carbon dioxide supplied to the exhaust gas by the first supply unit 8 The flow rate of hydrogen supplied to the exhaust gas by the second supply unit 9 is controlled so that the flow rate of the substance amount is the same as the total flow rate. As described above, the supply amount of carbon dioxide and the supply amount of hydrogen are controlled. As a result, the carbon dioxide conversion section 10 and the reforming reaction section 14 can generate reformed gas having the same composition as the carburizing gas.

Although the hydrogen supply source of the second supply unit 9 is not particularly limited, for example, from the viewpoint of suppressing the use of fossil fuels, hydrogen generated from a water electrolysis device (electrolysis device) is preferable. Alternatively, the second supply unit 9 may supply water vapor together with hydrogen to the exhaust gas. Thereby, carbon deposition in the methanation reaction section 11 can be suppressed. The control unit 7 can also control the supply amount of water vapor supplied to the exhaust gas by the second supply unit 9 based on the flow rate and component concentration of the exhaust gas.

The third supply section 15 may supply water vapor to the exhaust gas on the downstream side of the first concentration measurement section 6 in the gas flow path 20 . Thereby, carbon deposition in the methanation reaction section 11 can be suppressed. The control unit 7 can also control the amount of water vapor supplied to the exhaust gas by the third supply unit 15 based on the flow rate and component concentration of the exhaust gas.

The carbon dioxide conversion section 10 is arranged downstream of the first concentration measurement section 6 in the gas flow path 20, generates hydrocarbons or carbon monoxide from carbon dioxide, and removes water or oxygen. The carbon dioxide conversion unit 10 according to Embodiment 1 has a methanation reaction unit 11 and a water vapor removal unit 12 . The methanation reaction unit 11 generates methane (hydrocarbon) and water vapor (water) by catalytic reaction from the exhaust gas and the mixed gas of carbon dioxide and hydrogen supplied to the exhaust gas.

Specifically, in the methanation reaction unit 11, methane and water vapor are generated from carbon dioxide and hydrogen contained in the mixed gas by advancing the methanation reaction represented by the formula (2) through a catalytic reaction.

_CO2 +4H2->CH4 ₊ _2H2O ( ₂ )

Also, in the methanation reaction unit 11, the methanation reaction represented by Formula (3) proceeds simultaneously with the reaction represented by Formula (2). In the reaction represented by formula (3), methane and water vapor are produced from carbon monoxide and hydrogen contained in the mixed gas.

CO+3H2→CH4 ₊ _H2O ( ₃ )

When the reaction represented by formula (3) proceeds too much, the amount of heat absorbed by the reaction in the reforming reaction section 14 on the downstream side of the carbon dioxide conversion section 10 in the gas flow path 20 increases, and the energy consumption increases. There is a risk. Therefore, the reaction temperature of the reaction represented by the formula (2) in the methanation reaction section 11 is preferably 500° C. to 600° C. from the viewpoint of suppressing the progress of the reaction represented by the formula (3).

In the methanation reaction section 11, as described above, the mixed gas is converted into the converted gas by the reactions shown in the formulas (2) and (3).

As the methanation reaction unit 11, an appropriate reactor is selected to allow the reaction shown in formula (2) to proceed. The catalyst used in the methanation reaction section 11 is not particularly limited, but examples thereof include Ni-based catalysts.

The water vapor removal unit 12 removes water vapor from the converted gas and discharges it to the outside. A method for removing water vapor is not particularly limited, but examples thereof include condensation by cooling, adsorption separation, membrane separation, and the like.

The amount of water vapor to be removed is the same amount of oxygen as the oxygen contained in the carbon dioxide supplied to the exhaust gas by the first supply unit 8, and the same amount of hydrogen as the amount of hydrogen supplied to the exhaust gas by the second supply unit 9. of hydrogen is adjusted to be removed from the converted gas. Further, when water vapor is supplied to the exhaust gas by at least one of the third supply unit 15 and the second supply unit 9, the amount of water vapor removed by at least one of the third supply unit 15 and the second supply unit 9 is The same material amount of water vapor as was supplied to is also arranged to be removed from the converted gas. As described above, the reforming reaction section 14 can generate a reformed gas having the same composition as the carburizing gas.

The pressurizing section 13 is arranged downstream of the carbon dioxide conversion section 10 in the gas flow path 20, sucks the exhaust gas discharged from the carburizing furnace 3 into the gas flow path 20, and produces a reformed gas in the reforming reaction section 14. The gas is pressurized so as to obtain a pressure for supplying to the carburizing furnace 3. The boosting unit 13 is not particularly limited, but for example, a blower, a pump, or the like can be selected.

The converted gas from which water vapor has been removed is introduced into the reforming reaction section 14 via the gas flow path 20 . The reforming reaction section 14 is arranged downstream of the pressurizing section 13 in the gas flow path 20, and produces carbon monoxide and hydrogen by catalytic reaction from methane contained in the converted gas after water vapor removal.

Specifically, in the reforming reaction section 14, carbon monoxide and hydrogen are generated from methane and water vapor contained in the converted gas after water vapor removal by advancing the reaction shown in formula (4) through a catalytic reaction. Furthermore, by advancing the reaction shown in Formula (5) together with the reaction shown in Formula (4), carbon monoxide and water vapor are generated from carbon dioxide and hydrogen contained in the converted gas after water vapor removal.

CH4+ _H2O →CO+3H2 ( ₄ ) _CO2 ₊ H2→CO ₊ _H2O (5)

The reaction temperature of the reactions represented by formulas (4) and (5) in the reforming reaction section 14 is 900 from the viewpoint of suppressing carbon deposition and generating a reformed gas having the same composition as the carburizing gas. °C or higher is preferred. Moreover, from the viewpoint of suppressing deterioration of the reforming catalyst, the temperature is preferably 1200° C. or less. Moreover, from the viewpoint of making the composition similar to that of the carburizing gas, the same temperature as that of the RX gas generation section is preferable.

In the reforming reaction section 14, as described above, the converted gas from which water vapor has been removed is reformed by the reactions shown in formulas (4) and (5) to generate a reformed gas.

As the reforming reaction unit 14, an appropriate reactor is selected to allow the reactions shown in formulas (4) and (5) to proceed. As the reforming reaction section 14, the reactor used as the RX gas generation section 1 may also be used. The catalyst used in the reforming reaction section 14 is not particularly limited, but examples thereof include Ni-based catalysts.

The carburizing gas supply unit 40 is composed of the supply port 3a of the carburizing furnace 3 and the gas flow path 20 connected to the supply port 3a. , through the gas passage 20 and through the supply port 3a to the carburizing furnace 3.

Therefore, in the first embodiment, in the carburizing gas supply system 50, while reusing hydrogen, carbon monoxide, and nitrogen contained in the exhaust gas, carbon monoxide is regenerated from carbon dioxide, water vapor, etc. generated in the carburizing process. is doing. Therefore, the amount of carbon dioxide emissions can be reduced, and carbon monoxide can be regenerated from carbon dioxide, water vapor, and the like with little energy consumption. Furthermore, the amount of RX gas generated by the RX gas generator 1 and the amount of enriched gas added by the enriched gas supply unit 2 can be reduced according to the amount of the reformed gas supplied to the carburizing furnace 3 as the regeneration carburizing gas. . That is, the amount of new carburizing gas used can be reduced. As a result, energy consumption can be reduced during the entire process for carburizing with the carburizing system 100 . Moreover, since the amount of methane consumed by the RX gas generator 1 can be reduced, costs can be reduced.

Furthermore, in the first embodiment, the first supply unit 8 supplies carbon dioxide to the exhaust gas based on the flow rate and component concentrations of the exhaust gas measured by the first flow rate measurement unit 5 and the first concentration measurement unit 6. The supply amount of hydrogen supplied to the exhaust gas by the second supply unit 9 and the supply amount of water vapor supplied to the exhaust gas by the third supply unit 15 or the like can be controlled to optimum amounts. As a result, the carbon potential (CP) in the carburizing furnace can be adjusted to an optimum value by adjusting the amount of components such as carbon monoxide and hydrogen contained in the reformed gas to an optimum amount.

It should be noted that the carburizing gas supply system 50 preferably operates using renewable energy as electric power.

(Embodiment 2)
A carburizing gas supply system and a carburizing system according to the second embodiment will be described, focusing on the differences from the first embodiment. FIG. 3 is a schematic diagram of a carburizing gas supply system and a carburizing system according to a second embodiment.

The carburizing gas supply system 50 according to the second embodiment is arranged downstream of the first concentration measuring unit 6 and upstream of the carbon dioxide conversion unit 10 in the gas flow path 20, in addition to the configuration according to the first embodiment. A flow control unit 16 is further provided. Furthermore, unlike the first embodiment, the carburizing gas supply system 50 according to the second embodiment does not include the third supply section 15 .

The flow control unit 16 branches the exhaust gas after the concentration measurement, thereby introducing a part of the exhaust gas into the methanation reaction unit 11 of the carbon dioxide conversion unit 10 via the gas flow path 20, and transferring the remaining exhaust gas to By flowing it to the downstream side of the carbon dioxide conversion section 10 through the gas flow path 20 , the gas is directly introduced into the reforming reaction section 14 .

In the carburizing gas supply system 50 according to the second embodiment, the first supply unit 8 supplies carbon dioxide to a portion of the exhaust gas introduced into the methanation reaction unit 11, and the second supply unit 9 supplies carbon dioxide to a portion of the exhaust gas introduced into the methanation reaction unit 11. Hydrogen is supplied to part of the exhaust gas introduced into the section 11 . Then, a part of the exhaust gas and a mixed gas in which carbon dioxide and hydrogen supplied to the exhaust gas are mixed are introduced into the methanation reaction section 11 of the carbon dioxide conversion section 10 via the gas flow path 20 .

The reaction temperature of the reaction represented by formula (2) in the methanation reaction section 11 is preferably 200°C to 300°C from the viewpoint of increasing the reaction rate.

The reforming reaction unit 14 generates a reformed gas in which the remainder of the exhaust gas not introduced into the methanation reaction unit 11 and the converted gas after the removal of water vapor are reformed by the reactions shown in formulas (4) and (5). .

In the carburizing gas supply system 50 and the carburizing system 100 according to the second embodiment, the supply amount of carbon dioxide and the amount of hydrogen supplied in the first supply unit 8 and the second supply unit 9 are different from those described above. and the amount of water vapor removed by the water vapor removal unit 12 are the same as those of the first embodiment.

Therefore, in the second embodiment, the amount of exhaust gas introduced into the methanation reaction unit 11 is reduced by branching the exhaust gas after concentration measurement by the flow control unit 16, thereby reducing the amount of the exhaust gas introduced into the methanation reaction unit 11. size can be reduced. In addition, by controlling the flow rate of carbon dioxide and hydrogen supplied to the exhaust gas in the same manner as in the first embodiment, the ratio of the flow rate of the exhaust gas to which carbon dioxide is supplied to the flow rate of carbon dioxide supplied to the exhaust gas is reduced. Therefore, carbon deposition in the methanation reaction section 11 can be suppressed. Furthermore, the amount of methane produced in the methanation reaction section 11 can be controlled by causing the flow control section 16 to partially flow the exhaust gas after the concentration measurement to the bypass channel and to the downstream side of the carbon dioxide conversion section 10. Since it becomes possible, it becomes easy to control the reaction.

(Embodiment 3)
A carburizing gas supply system and a carburizing system according to the third embodiment will be described, focusing on the differences from the first embodiment. FIG. 4 is a schematic diagram of a carburizing gas supply system and a carburizing system according to the third embodiment.

The carburizing gas supply system 50 according to Embodiment 3, in addition to the configuration according to Embodiment 1, is arranged downstream of the first concentration measuring unit 6 and upstream of the carbon dioxide conversion unit 10 in the gas flow path 20. A separation section 17 (separation section) is further provided. Unlike the first embodiment, the carbon dioxide conversion unit 10 is arranged downstream of the separation unit 17 in the gas flow path 20, and includes the methanation reaction unit 11 or the carbon monoxide generation reaction unit 18 and the water vapor removal unit 12. and Furthermore, unlike the first embodiment, the carburizing gas supply system 50 does not include the third supply section 15 . Further, unlike the first embodiment, the pressurizing section 13 is arranged downstream of the first concentration measuring section 6 and upstream of the separating section 17 .

The separation unit 17 separates water vapor (water) and carbon dioxide from the exhaust gas whose concentration has been measured, and passes the separated gas containing water vapor and carbon dioxide as main components to the carbon dioxide conversion unit 10 through the gas flow path 20. By introducing the waste gas into the methanation reaction unit 11 or the carbon monoxide generation reaction unit 18 and flowing the remainder of the exhaust gas after the separation gas is separated downstream of the carbon dioxide conversion unit 10 through the gas flow path 20, It is introduced into the reforming reaction section 14 as it is.

The separation method of the separation gas of the separation unit 17 is not particularly limited, but includes, for example, adsorption separation, membrane separation, and the like. The adsorbent used for adsorptive separation is not particularly limited, but examples thereof include zeolite, ceria, molecular sieves, activated carbon and the like. By providing two reaction chambers in the separation unit 17 that performs adsorption separation, the adsorbent can be regenerated by changing the pressure, temperature, etc., in one reaction chamber while adsorption separation is performed in the other reaction chamber. In order to equalize the flow rate of the separation gas, a buffer may be provided between the separation section 17 and the location where the gas is supplied from the first supply section 8 in the gas flow path 20 .

In the carburizing gas supply system 50 according to Embodiment 3, the first supply unit 8 supplies carbon dioxide to the separation gas downstream of the separation unit 17 in the gas flow path 20, and the second supply unit 9 supplies the gas flow Hydrogen is supplied to the separation gas downstream of separation section 17 in line 20 . Then, the separation gas and the mixed gas of carbon dioxide and hydrogen supplied to the separation gas are supplied to the methanation reaction section 11 or the carbon monoxide generation reaction section 18 of the carbon dioxide conversion section 10 through the gas flow path 20. be introduced.

In the methanation reaction unit 11, methane and water vapor are generated from carbon dioxide and hydrogen contained in the mixed gas by advancing the methanation reaction represented by the formula (2) through a catalytic reaction. The reaction temperature of the reaction represented by formula (2) in the methanation reaction section 11 is preferably 200° C. to 300° C. from the viewpoint of increasing the reaction rate.

In the methanation reaction section 11, the mixed gas is converted by the reaction represented by the formula (2) as described above to generate a converted gas.

The carbon monoxide generation reaction unit 18 generates carbon monoxide and water vapor from carbon dioxide and hydrogen contained in the mixed gas by advancing the reaction shown in formula (5) through a catalytic reaction.

The reaction temperature of the reaction represented by formula (5) in the carbon monoxide generation reaction section 18 is preferably 700°C or higher from the viewpoint of increasing the reaction rate. Moreover, from the viewpoint of suppressing deterioration of the catalyst, the temperature is preferably 1200° C. or less. As the carbon monoxide generation reaction section 18, an appropriate reactor is selected to allow the reaction shown in the formula (5) to proceed. The catalyst used in the carbon monoxide generation reaction unit 18 is not particularly limited, but examples thereof include Ni-based catalysts and Cu-based catalysts. Cu-based catalysts are preferable from the viewpoint of suppressing the generation of methane. The carbon monoxide generation reaction section 18 may also serve as the water vapor removal section 12 by mixing zeolite with a catalyst and selectively adsorbing water vapor. In that case, the reaction represented by formula (5) proceeds even at low temperatures, so the reaction temperature can be reduced to 300° C. or lower.

In the carbon monoxide generation reaction section 18, the mixed gas is converted by the reaction represented by the formula (5) as described above to generate a converted gas.

The reforming reaction section 14 is arranged on the downstream side of the separation section 17 in the gas flow path 20, and the remainder of the exhaust gas after the separation gas is separated and the converted gas after removal of water vapor are expressed by the formulas (4) and (5). ) to generate a reformed gas reformed by the reaction shown in ).

In the carburizing gas supply system 50 and the carburizing system 100 according to the third embodiment, the supply amount of carbon dioxide and the amount of hydrogen supplied in the first supply unit 8 and the second supply unit 9 are different from those described above. and the amount of water vapor removed by the water vapor removal unit 12 are the same as those of the first embodiment.

Therefore, in Embodiment 3, water vapor and carbon dioxide are separated from the exhaust gas after concentration measurement by the separation unit 17, and the separated gas containing water vapor and carbon dioxide as main components is converted to the methanation reaction unit 11 or the carbon monoxide generation reaction. Since it is introduced into the methanation reaction unit 11 or the carbon monoxide generation reaction unit 18, the concentration of water vapor, carbon dioxide, etc. in the mixed gas to be reacted in the methanation reaction unit 11 or the carbon monoxide generation reaction unit 18 can be improved. Carbon deposition in the production reaction section 18 can be suppressed. Furthermore, the reaction in the methanation reaction section 11 or the carbon monoxide generation reaction section 18 is facilitated because it is not affected by hydrogen or carbon monoxide.

(Embodiment 4)
A carburizing gas supply system and a carburizing system according to the fourth embodiment will be described, focusing on the differences from the third embodiment. FIG. 5 is a schematic diagram of a carburizing gas supply system and a carburizing system according to a fourth embodiment.

In the carburizing gas supply system 50 according to the fourth embodiment, unlike the third embodiment, the carbon dioxide conversion section 10 has the electrolytic reaction section 19 instead of the methanation reaction section 11 or the carbon monoxide generation reaction section 18. , and does not have the water vapor removal section 12 . Furthermore, unlike the third embodiment, the carburizing gas supply system 50 does not include the second supply section 9 .

In the carburizing gas supply system 50 according to Embodiment 4, the first supply section 8 supplies carbon dioxide to the separation gas on the downstream side of the separation section 17 in the gas flow path 20 . Then, the mixed gas in which the separation gas and the carbon dioxide supplied to the separation gas are mixed is introduced into the electrolytic reaction section 19 of the carbon dioxide conversion section 10 via the gas flow path 20 .

At the fuel electrode of the electrolysis reaction unit 19, the reaction represented by the formula (6) is advanced by electrolysis, so that the carbon dioxide contained in the mixed gas, that is, the carbon dioxide contained in the separated gas and the dioxide supplied to the separated gas Produces carbon monoxide from carbon. At the same time, hydrogen is generated from the water vapor (water) contained in the mixed gas as the reaction represented by the formula (7) proceeds. At this time, the amount of current in the electrolysis is controlled so that the carbon dioxide contained in the mixed gas is converted to carbon monoxide. is also used, so not all carbon dioxide is converted to carbon monoxide.

CO ₂ +2e ⁻ →CO+O ²⁻ (6) H ₂ O+2e ⁻ →H ₂ +O ²⁻ (7)

On the other hand, at the oxygen electrode of the electrolysis reaction unit 19, oxygen is generated from oxide ions by advancing the reaction shown in formula (8) by electrolysis. The electrolytic reaction section 19 discharges the oxygen to the outside.

O ²⁻ →0.5O ₂ +2e ⁻ (8)

In the electrolytic reaction section 19, as described above, the mixed gas is converted into the converted gas by the reactions shown in the formulas (6) to (8).

The electrolysis reaction unit 19 is not particularly limited, but includes a solid oxide cell capable of co-electrolysis of water vapor and carbon dioxide.

The reforming reaction section 14 is arranged on the downstream side of the electrolytic reaction section 19 in the gas flow path 20, and the remainder of the exhaust gas and the converted gas after the separation gas is separated are represented by the formulas (4) and (5). A reformed gas that is reformed by the reaction is generated.

The carburizing gas supply system 50 and the carburizing system 100 according to the fourth embodiment are the same as those of the third embodiment except for the method of controlling the amount of carbon dioxide supplied in the first supply unit 8. is.

Therefore, in the fourth embodiment, the functions of the second supply unit 9 and the carbon monoxide generation reaction unit 18 according to the third embodiment can be integrated into the electrolytic reaction unit 19, so the configuration can be simplified compared to the third embodiment. . Also, by controlling the amount of electric current in electrolysis, it becomes possible to control the reaction rate, which facilitates the control of the reaction.

The present invention is not limited to the embodiments. However, it is included in the technical scope of the present invention and includes various modifications. For example, the embodiments are described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the described configurations. Also, part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Moreover, it is possible to add, delete, or replace part of the configuration of each embodiment with another configuration.

1 RX gas generation unit 2 Enriched gas supply unit 3 Carburizing furnace 4 Combustion equipment 5 First flow measurement unit 6 First concentration measurement unit 7 Control unit 8 First supply unit 9 Second supply unit 10 Carbon dioxide conversion unit 11 Methanation reaction Section 12 Water vapor removing section 13 Pressure increasing section 14 Reforming reaction section 15 Third supply section 16 Flow rate control section 17 Separation section 18 Carbon monoxide generation reaction section 19 Electrolysis reaction section 20 Gas flow path 21 Second flow measurement section 22 Second concentration Measurement Section 30 Gas Discharge Section 40 Carburizing Gas Supply Section 50 Carburizing Gas Supply System 100 Carburizing System All publications, patents and patent applications cited herein are hereby incorporated by reference in their entirety.

Claims

In a carburizing gas supply system that supplies carburizing gas to a carburizing furnace that performs carburizing,
a gas discharge unit for discharging exhaust gas from the carburizing furnace;
a first flow rate measurement unit that measures the flow rate of the exhaust gas;
a first concentration measuring unit for measuring concentrations of components of the exhaust gas;
a first supply unit that supplies carbon dioxide to the exhaust gas;
a control unit that controls the supply amount of the carbon dioxide based on the flow rate and the concentration of the component of the exhaust gas;
a carbon dioxide conversion unit that produces hydrocarbons or carbon monoxide from carbon dioxide and removes water or oxygen;
a carburizing gas supply unit for supplying the regenerated carburizing gas containing the hydrocarbons or carbon monoxide generated in the carbon dioxide conversion unit to the carburizing furnace.
The carburizing gas supply system further includes a second supply unit that supplies hydrogen to the exhaust gas,
2. The gas supply system for carburizing according to claim 1, wherein the control unit controls the supply amount of the hydrogen based on the flow rate of the exhaust gas and the concentration of the component.
The carburizing gas supply system according to claim 2, wherein the second supply unit has an electrolytic device.
The carburizing gas supply system according to any one of claims 1 to 3, wherein the carbon dioxide conversion unit has a catalyst that produces hydrocarbons or carbon monoxide from carbon dioxide.
The carburizing gas supply system further includes a third supply unit that supplies water to the exhaust gas,
5. The gas supply system for carburizing according to claim 4, wherein the control unit controls the supply amount of the water based on the flow rate and the concentration of the component of the exhaust gas.
The carburizing gas supply system according to claim 1, wherein the carbon dioxide conversion unit has an electrolytic reaction unit that generates carbon monoxide by electrolysis of carbon dioxide.
The carburizing gas supply system further comprises a reforming reactor having a catalyst,
The reforming reactor produces carbon monoxide and hydrogen from the hydrocarbon produced from the carbon dioxide conversion unit,
7. The carburizing gas supply unit according to any one of claims 1 to 6, wherein the regenerated carburizing gas containing the carbon monoxide generated in the reforming reactor is supplied to the carburizing furnace. 2. The gas supply system for carburizing according to item 1.
The carburizing gas supply system further comprises a flow rate control unit arranged upstream of the carbon dioxide conversion unit,
The flow rate control unit introduces a portion of the exhaust gas into the carbon dioxide conversion unit based on the flow rate of the exhaust gas and the concentration of the component, and causes the remainder of the exhaust gas to flow downstream of the carbon dioxide conversion unit. The carburizing gas supply system according to any one of claims 1 to 7, characterized in that:
The carburizing gas supply system further comprises a separation section arranged upstream of the carbon dioxide conversion section,
8. The separation unit separates water and carbon dioxide from the exhaust gas, and supplies the separated water and carbon dioxide to the carbon dioxide conversion unit. The gas supply system for carburizing described in .
The gas supply system for carburizing according to claim 9, wherein the separation unit adsorbs and separates the water and the carbon dioxide from the exhaust gas.
The carburizing gas supply system further comprises a second flow rate measuring section and a second concentration measuring section,
The second flow rate measuring unit measures the flow rate of the regeneration carburizing gas,
The carburizing gas supply system according to any one of claims 1 to 10, wherein the second concentration measuring unit measures the concentration of the component of the regenerating carburizing gas.
The gas supply system for carburizing according to any one of claims 1 to 11, which is operated by using renewable energy as electric power.
A carburizing system comprising: the carburizing gas supply system according to any one of claims 1 to 12; and a carburizing furnace for carburizing.