N2-free co gas for synthetic fuels or method for producing co2 gas

Abstract

If oxygen is blown in place of air into a blast furnace through the tuyeres, then a blast furnace gas does not contain N2 and can be a raw material for synthetic fuels. However, there is a problem wherein the amount of a gas generated in front of tuyeres decreases and it is difficult to control the temperature in front of tuyeres and a thermal flow ratio. Provided is a method for producing hydrogen and an N2-free CO gas for synthetic fuels, the method comprising operating a blast furnace so that: oxygen is blown thereinto in place of air through the tuyeres; water vapor and a recycled CO gas are further blown through the tuyeres; a CO2 gas is separated from a blast furnace gas discharged from the blast furnace top and is collected; an H2 gas is separated from an H2 gas / CO gas mixture which has resulted from the CO2 separation; some of the CO gas which has resulted from the H2 gas separation is collected; and the remaining CO gas, which has resulted from the collection of some CO gas, is heated as a recycled CO gas together with water vapor, and the resultant mixture is blown through the tuyeres of the blast furnace. The method is characterized in that the amount of gases to be generated in front of the tuyeres is made substantially the same as that in the ordinary blast furnace into which air is blown.

Description

Method for producing CO gas or CO2 gas for synthetic fuel containing no N2

[0001] The present invention relates to a method for producing CO gas or CO2 gas for synthetic fuel containing no N2.

[0002] Due to the recent demand for carbon neutrality, there has been active development of synthetic fuels (e-fuels). Synthetic fuels (e-fuels) are a new fuel that can replace gasoline, and are liquid fuels for engine vehicles, large trucks, aviation fuel (SAF) for aircraft where electrification is difficult, and ships. They are widely expected to replace petroleum. At the end of March 2023, Europe allowed the sale of engine vehicles that use synthetic fuels, attracting attention. Because synthetic fuels are made by capturing CO2, emissions are offset by the amount captured, and the result is a "net-zero" count. If synthetic fuels are used in engine vehicles, CO2 emissions will be zero. In other words, synthetic fuels are fuels that "do not increase CO2 in the atmosphere" when considered in total from production to use, in other words, they are "carbon neutral" fuels. N ２ CO-free gas is a feedstock for synthetic fuels. ２ From the reverse shift reaction (CO2 + H ２ →CO+H ２ However, this reaction requires high temperatures and is costly, so much money and manpower is being spent on its development. On the other hand, blast furnaces emit large amounts of CO and CO2 gases. However, conventional blast furnace gas contains N ２ Since it contains N2, it cannot be used as a raw material for synthetic fuel. If it is possible to remove N2 from blast furnace gas and provide CO2 gas that does not contain N2, it can be used as a raw material for synthetic fuel, which will contribute to the provision of new energy and at the same time reduce carbon dioxide emissions. Patent Document 1 describes a method for producing CO2 gas by removing N2 from the blast furnace tuyere. ２ O or CO ２ ) is injected into the furnace top, and preheat gas is injected into the furnace bottom. The blast furnace gas not containing N2 is obtained from the top of the blast furnace, and a part of it is de-CO ２Patent Document 2 describes a method of treating the blast furnace with a treatment device and using the resulting CO gas as a raw material for synthetic fuel. ２ and CO ２ After the CO gas is removed, N2 gas is blown in through the tuyeres and circulated. ２ There is a statement about reducing emissions.

[0003] JP 1985-159104 A International Publication WO / 2023 / 153407

[0004] Conventional blast furnace gas contains a large amount of N2 gas and cannot be used as a raw material for synthetic fuel. However, there have been attempts to use CO2 gas emitted from the top of a blast furnace as a raw material for chemical synthesis.

[0005] Patent Document 1 aims to obtain N-free blast furnace gas discharged from the top of a blast furnace in an oxygen operation in which oxygen is injected into the blast furnace tuyere instead of air, and to use the resulting CO gas as a raw material for chemical synthesis. However, this operation does not inject N from the tuyere, resulting in an increase in the raceway temperature before the tuyere (Tf). Furthermore, the lack of N injected from the tuyere results in an insufficient amount of gas in the blast furnace, resulting in an excessive heat flow ratio (the ratio of the heat capacity of the solid to the heat capacity of the gas), which in turn results in insufficient heat transfer from the furnace gas to the charge, resulting in a decrease in the pig iron temperature. To address the increase in the raceway temperature before the tuyere (Tf), a cooling gasifier (HO or CO) is injected from the tuyere. To prevent an excessive heat flow ratio, N-free preheat gas is injected from the middle of the furnace. However, injecting N-free preheat gas from the middle of the furnace has the problem that the injected preheat gas does not reach the vicinity of the furnace center. In addition, a device for blowing preheated gas that does not contain N2 into a blast furnace from the middle of the furnace is large-scale and places a heavy burden on the furnace. Patent Document 2 circulates N2 gas together with blast furnace CO gas, and ２ Although this method is effective in reducing emissions, N2 is mixed into the CO gas, making it impossible to use it as a raw material for synthetic fuels.

[0006] The present invention provides the following: (1) A method for producing CO gas for synthetic fuel that does not contain N2, which comprises blowing oxygen into a blast furnace through a tuyere instead of air, separating and recovering CO2 gas from the blast furnace gas discharged from the top of the blast furnace, recovering a portion of the CO2 gas after the CO2 separation and recovery, and blowing the remaining CO gas through the blast furnace tuyere as recycled CO gas, and which is characterized in that the amount of gas generated before the tuyere is equivalent to that of a normal air-blowing blast furnace. (2) A method for producing CO gas and hydrogen for synthetic fuel that does not contain N2, comprising the steps of: injecting oxygen into a blast furnace through the tuyere instead of air, and further injecting steam and recycled CO gas through the tuyere to separate and recover CO2 gas from the blast furnace gas discharged from the top of the blast furnace; separating and recovering H2 gas from a mixed gas of CO gas and H2 gas after CO2 separation; recovering a portion of the CO gas after H2 gas separation, and recycling the remaining CO gas after recovering a portion of the CO gas, which is then heated together with steam and injected through the blast furnace tuyere, wherein the amount of gas generated before the tuyere is equivalent to that of a blast furnace with normal air blowing. (3) A method for producing CO2 gas, comprising the steps of: injecting oxygen into a blast furnace through the tuyere instead of air, and separating and recovering CO2 gas from the blast furnace gas discharged from the top of the blast furnace; (4) A method for producing CO gas for synthetic fuel that does not contain N2, by separating and recovering CO2 gas from a mixed gas of CO, CO2, and N2 discharged from the top of an air-blowing blast furnace, and separating and recovering CO from the mixed gas of CO and N2 after the CO2 separation and recovery.

[0007] Here, blast furnace operation in which oxygen is blown into the blast furnace tuyere instead of air is sometimes referred to as "oxygen operation." Separating and removing CO2 gas from the blast furnace gas discharged from the top of the blast furnace and blowing the CO gas after CO2 separation and removal into the blast furnace tuyere is sometimes referred to as "CO gas recycling." CO gas that does not contain N2 is sometimes referred to as "N2-free CO gas."

[0008] In the oxygen blast furnace, CO gas is recycled to ２It is possible to produce CO2-free gas and provide it as a raw material for synthetic fuel (e-fuel). ２ It is possible to provide hydrogen together with CO2 gas for synthetic fuel that does not contain CO2 gas. In oxygen blast furnaces, CO2 gas emissions can be reduced by recycling CO2 gas. In air-blast blast furnaces, CO2 gas can be separated and recovered from blast furnace gas to produce N2 gas. ２ CO2-free gas can be produced and used as a raw material for synthetic fuel (e-fuel).

[0009] Figure 1 shows a basic operation. Figure 2 shows a method for producing N2-free CO gas by recycling CO gas in oxygen operation (Example 1). Figure 3 shows a method for producing hydrogen and N2-free CO gas by recycling CO gas in oxygen operation and injecting steam through the tuyeres (Example 2). Figure 4 shows a method for producing CO2 gas by recycling CO gas (Example 3). Figure 5 shows a method for producing N2-free CO gas by separating and recovering CO gas from a mixed gas of CO, CO2, and N2 discharged from the top of an air-blowing blast furnace (Example 4).

[0010] The production of synthetic fuel (e-fuel) requires CO gas that does not contain N2 gas. In oxygen operation, CO gas that does not contain N2 gas is produced by blowing oxygen into the tuyere instead of air. Oxygen operation eliminates the need for N2 to be blown into the tuyere, reducing the amount of gas before the tuyere, resulting in an increase in the raceway temperature before the tuyere and an increase in the heat flow ratio. However, this is premised on the smooth operation of the blast furnace, which can produce the intended pig iron. The blast furnace operation design for this purpose is as follows: (1) Ensure the amount of gas in the raceway before the tuyere and prevent an increase in the heat flow ratio (the ratio of the heat capacity of the solid to the heat capacity of the gas). (2) Maintain the temperature before the tuyere, Tf, at 2000°C to 2300°C, the same as conventional blast furnaces. This section discusses blast furnace operation methods that meet the above conditions.

[0011] (Base operation) Comparative Example 1 (Table 1) Figure 1 Base operation will be explained first for comparison with the present invention. Base operation is the blast furnace operation that was normally carried out before the present invention. The assumptions for the base operation are as follows: (1) For ease of understanding, the base operation is an all-coke operation with a blast volume of 100 Nm3 per unit time. ３ (N2 is 79 Nm ３ , O2 is 21 Nm ３ (2) The indirect reduction rate in the blast furnace is 70%. The direct reduction rate is 30%. (3) The gas utilization rate (ηCO) of the blast furnace is 50%. (4) All the ores charged are Fe ２ O ３ (5) Although some of the charged carbon enters the pig iron, it is not directly involved in the reaction in the blast furnace, so in this study we will discuss iron that does not contain carbon.

[0012] The operating conditions of blast furnace 1 during base operation are shown in Figure 1. Blast flow rate: 100 Nm ３ This is the calculation of the hit. N2 is 79Nm ３ , O ２　 is 21Nm ３ The gas composition in the raceway before the tuyere is 79 Nm ３ , O ２ is C+O ２　 → In the reaction of 2CO, CO is 42Nm ３ The composition of the lower shaft is as follows: A portion of the carbon is directly reduced from FeO + C to Fe + CO, and CO is converted to XNm ３ The amount of CO generated by direct reduction is XNm ３ is 42 Nm before the tuyere ３ This contributes to indirect reduction together with the CO generated in the lower furnace. Since the gas utilization rate is 50%, only half of the CO generated in the lower furnace contributes. The direct reduction rate is assumed to be 30%, and the following formula holds: Here, the numerator corresponds to the amount of oxygen taken by direct reduction. The denominator is the sum of the CO generated before the tuyere and the CO (X) generated by direct reduction, which is half (gas utilization rate 50%) of the total, which corresponds to the oxygen taken by indirect reduction, and is the sum of the oxygen taken by direct reduction. From this formula, X = 11.45, and the CO at the bottom of the shaft is 53.45 Nm３ The furnace top gas composition is 42 + 11.45. The blast furnace gas utilization rate (ηCO) is 50%, so the CO generated at the bottom of the shaft is 53.45 Nm ３ and half of CO at the furnace top. ２ and CO. ２ is 26.73 Nm ３ , remaining CO is 26.73 Nm ３ All of the carbon charged is CO or CO contained in the furnace gas. ２ Therefore, the amount of gasified carbon charged is 2.386 kmol (53.45 / 22.4), or 28.63 kg (2.386 x 12).

[0013] Iron production can be calculated from the oxygen balance. The oxygen from the blast is 30 kg (21 Nm ３ The oxygen contained in the furnace gas is 57.27 kg (26.73 Nm ３ / 22.4×16kg + 26.73 Nm ３ The oxygen removed from the iron ore is 27.27 kg (57.27 - 30). The oxygen in the iron ore is 0.8522 moles (27.27 / 32). Therefore, the iron production is 63.62 kg (breakdown: 27.27 x 112 / 48). Here, 112 / 48 is the amount of Fe ２ O ３ The iron to oxygen ratio in the pig iron is (56 x 2 / 16 x 3). The pig iron production is 66.62 kg (63.62 / 0.955 → 4.5% carbon in the pig iron). The gasified coke charge is 31.81 kg (28.63 / 0.9 → 90% carbon in the coke). 28.63 is the amount of gasified carbon charged (see paragraph "0012" above). The gasified coke rate is 477 kg / tpig (31.81 kg / 66.62 kg). The coke rate is 522 kg / tpig (477 + 45, plus 45 kg of carbon in the pig iron).

[0014] (Heat input during base operation) Next, the heat input during base operation is calculated. In FIG. 1, the heat input sources to the blast furnace 1 are charged carbon and sensible heat of the blast heated by the hot stove 2. The charged carbon reacts with oxygen in the blast furnace and is oxidized to produce CO２ and CO, which are released as furnace top gas. ２ and the heat of formation of CO. Therefore, the heat input to the blast furnace 1 is ２ and the sum of the heat of CO production and the sensible heat of airflow.

[0015] (1) CO of charged carbon ２ In Figure 1, half of the charged carbon (2.386 kmoles) is 1.193 kmoles. ２ Therefore, the heat generation amount is 112.2 × 10 ３ kcal (breakdown: 1.193 kmoles x 393.5 kJ / mol x 0.239 cal / j x 10 ３ kcal). 393.5 kj / mol is the carbon dioxide from C to CO ２ The heat generated by oxidation to (C + O ２ =CO ２ , ΔH = -393.5 kJ / mol). The standard heat of formation of gas ΔH is taken from Basic Chemistry 21st Edition (Shokabo), p. 132.

[0016] (2) The reaction heat of the charged carbon to CO is 31.51 × 10 because half of the charged carbon (2.386 kmoles) (1.193 kmoles) became CO in Figure 1. ３ kcal (breakdown: 1.193 kmole x 110.5 kJ / mol x 0.239 cal / j x 10 ３ The heat of formation of CO gas is ΔH = -110.5 kj / mol.

[0017] (3) The temperature of the airflow is 1000°C. The sensible heat of the airflow is 33.78 x 10 ３ kcal (breakdown: N ２ ;26.37 x 10 ３ kcal + O ２ 7.41 x 10 ３ kcal). N ２ The sensible heat is 26.37 x 10 ３ kcal (breakdown: 79 Nm ３ / 22.4) × 28 kg × 0.267 cal / kg × 1000 °C), and O ２ The sensible heat is 7.41 x 10 ３ kcal (breakdown: (21 Nm ３ / 22.4) × 32 kg × 0.247 cal / kg × 1000 °C), where 0.267 cal / kg and 0.247 cal / kg are the N ２ and O ２ The specific heat capacity is 1000°C.

[0018] (4) The total heat input is 177.5 x 10 ３ kcal. Breakdown: 112.2 x 10 ３ kcal+31.5×10 ３ kcal+33.78×10 ３ In Figure 1, 177.5 x 10 kcal is required to produce 63.62 kg of iron. ３ kcal of heat is required. This heat includes the heat of iron reduction, the heat carried away by pig iron and slag, heat dissipated by the furnace body, and others. The breakdown is as follows: heat of iron reduction (67.6%), sensible heat of molten iron and slag (17.2%), sensible heat of furnace top gas (6.2%), heat loss from the furnace body, and others (Ironmaking and Steelmaking, Asakura Publishing, p. 22).

[0019] (Tyreway temperature Tf during base operation) In a blast furnace, it is important to ensure not only heat throughout the entire furnace, but also heat in the lower part of the furnace. It is important that the tuyere raceway temperature Tf calculated from the heat balance in the lower part of the furnace is an appropriate temperature. (Heat input to the tuyere raceway) (1) Sensible heat of blast: 33.78 x 10 ３ kcal See paragraph "0017" (2) Heat of carbon combustion 49.53 x 10 ３ kcal Calculation details: (1.875 kmole x 110.5 kj / mol x 0.239 Cal / j) 1.875 is the oxygen concentration of 21 Nm3 in the air ３ The amount of carbon burned in (2C+O ２ = 2CO) (3) Heat capacity of carbon entering the raceway before the tuyere 20.25 x 10 ３ kcal Calculation: (42 / 22.4) kmol x 6 cal / kmol x (2100°C x 0.75) = 20.25 x 10 ３kcal. Assuming that the raceway temperature before the tuyere is 2100°C, 2100°C x 0.75 is the carbon temperature entering the raceway before the tuyere, which is 0.75 of the temperature before the tuyere (Ram's formula). 6 cal / kmole is the specific heat of carbon at 2100°C. (4) Total heat input to the raceway before the tuyere: 103.6 x 10 ３ kcal ・Calculation details; 33.78×10 ３ kcal+49.53×10 ３ kcal+20.25×10 ３ kcal (Calculation of the raceway temperature Tf before the tuyere) (1) Heat capacity of the gas in the raceway ・N ２ 79 Nm ３ Heat capacity: 79 / 22.4 x 28 x 0.29 x Tf = 28.64 Tf CO42 Nm ３ Heat capacity of 42 / 22.4 x 28 x 0.292 x Tf = 15.33Tf 28 is N ２ The molecular weights of N and CO, 0.29 and 0.292, are the values ​​when Tf is assumed to be 2100 °C. ２ and the specific heat of CO. (2) Raceway temperature Tf 103.6×10 ３ kcal= (28.64Tf+15.33Tf)×10 ３ From kcal, Tf = 2356°C is obtained. (3) In all-coke operation, the raceway temperature in front of the tuyere reaches a high temperature of 2356°C, but in actual operation, it is thought that the temperature will reach around 2100°C due to the injection of pulverized coal.

[0020] (N by CO gas recycling ２ Method for producing free CO gas) Invention Example 1 (Table 1) Figure 2 Invention Example 1 is a method for producing N ２ Free CO is produced in a blast furnace. Conventionally, CO generated in factories and thermal power plants is all produced in air combustion, so ２ In the present invention, N is used in the blast furnace. ２ To produce free CO, oxygen operation is carried out by blowing only oxygen into the blast furnace tuyeres instead of the conventional air blowing. When oxygen is substituted for air, the N in the air ２Therefore, in Example 1, in order to secure the amount of gas in front of the tuyere when only oxygen is blown into the blast furnace tuyere instead of the conventional air blowing, the N in the blast furnace gas is reduced. ２ Instead of the content, CO gas is recycled. Oxygen blown into the tuyere is 21 Nm ３ CO gas is 79 Nm ３ By recycling, the amount of gas before the tuyere is kept at the same level as in base operation, and the temperature before the tuyere and the heat flow ratio are kept at the same level as in base operation. Specifically, when oxygen operation is first started, the generated CO is not recovered but is stored in the CO gas relay tank 4. The oxygen blown into the tuyere is 21 Nm ３ CO gas is 79 Nm ３ Once the storage has been completed, tuyere injection of CO gas from the relay tank 4 begins. Furthermore, in conventional operations, pulverized coal is generally injected, so by injecting recycled CO gas instead of pulverized coal, it is possible to prevent the temperature before the tuyere from rising. The only carbon source that generates gas in the blast furnace is carbon C, which is charged from the furnace top. The C charged into the blast furnace becomes CO2 and CO through new reactions inside the blast furnace. The newly generated CO2 and CO are recovered from the blast furnace circulation system to external recovery product tanks, respectively. The recycled CO is the CO gas that was initially stored in the relay tank. Of course, the newly generated CO gas and the CO gas stored in the relay tank are mixed, but it is the amount of CO gas that was initially stored in the relay tank that is recycled. The CO gas that is released to the outside and recovered is N ２ As free CO, it can be used as a raw material for synthetic fuel (e-fuel).

[0021] Here, the difference between the blast furnace gas recycling of the present invention and the conventional blast furnace gas recycling will be explained. The purpose of the conventional blast furnace gas recycling is to reduce the coke ratio (i.e., CO ２ The blast furnace gas utilization rate ηCO is about 50%, and unused CO gas is recycled and blown into the tuyeres for ore reduction. ２On the other hand, the purpose of the blast furnace gas recycling of the present invention is to ２ The CO2-free gas is recovered as much as possible and provided as a raw material for synthetic fuel (e-fuel). Since it is provided as CO2 gas in the synthetic fuel manufacturing process, ２ This results in a reduction in CO2 emissions (see paragraph "0064"). That is, in Invention Example 1, the amount of gas before the tuyere is secured by recycling CO2 gas, and CO generated by charging C is recovered. The CO2 gas recycling of the present invention and the conventional CO2 gas recycling for reducing CO2 emissions are different in method and purpose.

[0022] (Overall heat balance of the blast furnace and lower furnace heat balance) ２ An example of a blast furnace operation method for producing free CO is shown below. In oxygen operation, the same iron content as in the base operation (63.62 kg) was produced in the blast furnace per oxygen injection of 21 Nm3 as in the base operation shown in Figure 1, the carbon charge amount was Y kmol, and the CO gas recycling amount was 79 Nm3 instead of nitrogen. ３ The charged Yk moles of carbon react in the blast furnace, and at the top of the furnace, CO ２ The calculation is based on the assumption that the amount of CO gas is 50%.

[0023] (N ２ Overall heat balance of blast furnace operation for free CO production (required heat amount of the entire blast furnace) The same 63.62 kg of iron as in base operation is produced, and the required heat amount of the entire blast furnace is 177.5 x 10 ３ (1) The heat input from the combustion of C is 60.2Y × 10 ３ kcal. Explanation: The charged Yk moles of carbon are 50% CO2 and 50% CO gas. ２ exotherm; 0.5Y x 393.5 kj / mol x 0.239 Cal / j x 10 ３ Heat release of CO: 0.5Y x 110.5 kj / mol x 0.239 Cal / j x 10 ３ From the sum of the heat generated by the above formula, the heat input due to the combustion of C is 60.2Y x 10 ３ kcal. C to CO ２ The heat of combustion is the chemical reaction C + O２ =CO ２ , ΔH = -393.5 kj / mol. C + 1 / 2O ２ = CO, ΔH = -110.5 kj / mol. The standard heat of gas formation ΔH is from Basic Chemistry 21st Edition (Shokabo), p. 132. 1j = 0.239 cal. (2) The sensible heat of CO gas injected into the tuyere is 26.66 x 10 ３ kcal. Explanation: 79 / 22.4 x 28 kg x 0.27 kcal / kg x 1000°C. 79 Nm ３ of CO is heated to 1000°C. 28 kg is the molecular weight of CO (kg / kmol), and 0.27 kcal / kg is the specific heat of CO at 1000°C. ２ The purpose is to produce free CO gas, 79 Nm ３ In the CO recycling, 0.5Yk moles of CO generated by charging Yk moles of C was collected and recovered, and the remaining 79Nm ３ In actual operation, after oxygen operation starts, the amount of recycled CO gas required is 79 Nm ３ After being stored in a relay tank, 0.5Yk moles of N ２ Free CO gas is collected. (3) The total heat input is 60.2Y x 10 ３ kcal+26.66×10 ３ kcal.

[0024] The iron production is 63.62 kg, the same as the base operation. ３ kcal is required (see paragraph "0018"). Therefore, 60.2Y x 10 ３ kcal+26.66kcal=177.5×10 ３ From kcal, we get Y = 2.506 kmoles. If 2.506 kmoles of carbon is charged, the heat capacity of the entire blast furnace can be secured.

[0025] (Ensuring heat quantity in the lower part of the furnace) In a blast furnace, it is important to ensure not only the heat quantity of the entire blast furnace but also the heat quantity in the lower part of the furnace. In the blast furnace 1 in Figure 2, iron ore is charged from the top of the furnace, heated and reduced as it descends inside the furnace, and finally, high-temperature molten pig iron is discharged from the lower part of the furnace. By ensuring the heat quantity in the lower part of the furnace, the temperature of the molten pig iron flowing out from the lower part of the furnace is ensured. As an index of the heat quantity in the lower part of the furnace, the target is to set the tuyere raceway temperature Tf at 2000°C to 2300°C. In this calculation, the amount of CO gas generated in the raceway in front of the tuyere is set to 121 Nm3, the same as in conventional operation. ３ When this is the case, the temperature Tf of the raceway before the tuyere is calculated from the heat quantity of the gas entering and leaving the raceway before the tuyere.

[0026] (Heat input to the raceway before the tuyere) (1) The heat input due to the combustion of C to CO before the tuyere is 49.52 × 10 ３ kcal. Explanation: 21 / 22.4 x 2 x 110.5 x 0.239 x 10 ３ kcal 21 Nm injected into the tuyere ３ of oxygen combusts to 2 kmoles of CO (2C + O ２ = 2CO). The heat of CO combustion of C is 110.5 kj / mol (the heat of CO formation is ΔH = -110.5 kj / mol). (2) Sensible heat of CO injected into the tuyere: 26.66 x 10 ３ kcal. Explanation: See paragraph "0023". (3) The heat capacity of the carbon entering the raceway before the tuyere is 17.72 x 10 ３ kcal. Explanation: 21 / 22.4 x 2 x 6 x 2100°C x 0.75 The carbon entering the pre-tuyere raceway from above is heated and has heat capacity. The carbon temperature entering the pre-tuyere raceway is set to 0.75 times the pre-tuyere raceway temperature Tf (RAM formula). 21 Nm ３ is the O blown into the tuyere ２ The amount, 6 cal / K mol, is the specific heat of carbon at 2100°C, and the temperature of the raceway before the tuyere, Tf, is assumed to be 2100°C. (4) The total heat input to the raceway before the tuyere is 93.9 x 10 ３ kcal.

[0027] (Heat capacity of gas exiting the raceway) (1) The heat capacity of CO2 exiting the raceway is 43.71 Tf × 10 ３ kcal. Explanation 121 / 22.4 x 28 x 0.289 x Tf 121 is the tuyere blowing 21 Nm ３ CO generated by oxygen and recycled 79 Nm ３ The total of CO. 28 is the molecular weight of CO (kg), and 0.289 is the specific heat of CO (kcal / kg °C) assuming Tf is 2100 °C. (2) Raceway temperature From the heat balance, it is 93.9 x 10 ３ kcal=43.71Tf×10 ３ kcal Tf = 2148°C.

[0028] (Gas amount before the tuyere) CO: 42 Nm ３ CO : 79 Nm ３ Total recycled amount: 121 Nm ３ (Product gas amount) CO: 28.1 Nm ３ 2.506 kmoles x 0.5 x 22.4 CO 2　　 ; 28.1 Nm ３ 2.506 kmoles x 0.5 x 22.4

[0029] (Coke ratio) Gasification C charge Y = 30.07 kg (2.506 kmole x 12) Gasification coke = 33.41 kg (30.07 / 0.9 ASH in coke; 10%) Gasification coke ratio = 501.5 kg / tpig (33.41 / 66.62 kg ← pig amount) Coke ratio = 546.5 kg / tpig (501.5 + 45 ← C in pig)

[0030] (O / C of the shout section) O / C of the shout section = 2.7 (1500 kg / 546.5 kg; 1500 is the amount of ore (kg) required to produce 1000 kg of pig iron)

[0031] (Invention in which 0.8 kmoles of heated steam is injected) Invention Example 2, Explanation of Figure 3 The outline of the present invention will be explained using Figure 3. In a blast furnace that produces pig iron, hydrogen and CO gas for liquid fuel can be produced. In a conventional blast furnace in a steelworks, carbon (C) is charged from the top of the furnace, air is sent from the tuyeres at the bottom of the furnace, the C is burned, and iron ore is heated and reduced in the furnace to produce molten pig iron. CO generated not only in blast furnaces but also in factories and thermal power plants is burned in air, so N ２ In the present invention, in order to produce CO gas and hydrogen that do not contain N2 in a blast furnace, oxygen operation is carried out in which only oxygen is blown into the blast furnace tuyere instead of the conventional air blowing. When oxygen is substituted for air, the N in the air ２ Since there is no air blowing, the temperature in front of the blast furnace rises too much. This causes an increase in the heat flow ratio (the ratio of the heat capacity of the solid to the heat capacity of the gas) in the blast furnace. In other words, the amount of gas in front of the tuyere decreases, so the amount of gas in the furnace decreases, and the heat transfer from the gas in the furnace to the contents (ore, etc.) in the furnace decreases, causing a drop in the temperature of the molten iron and making continuous operation difficult. Therefore, the present invention injects only oxygen from the blast furnace tuyere instead of the conventional air blowing, and in this case, in order to adjust the temperature in front of the tuyere and ensure the amount of gas in front of the tuyere, the N in the blast furnace gas is ２ Instead of the above, part of the CO gas in the blast furnace gas is recycled and heated steam is injected from the tuyere. Although there are cases where steam is injected into the tuyere for the purpose of lowering the temperature before the tuyere, in the present invention, the purpose is to inject as much steam as possible to increase the amount of CO gas generated that does not contain hydrogen or N2. That is, the steam injected into the tuyere is heated to a high temperature of 1000°C or more in the raceway before the tuyere, and the H ２ O + C → CO + H ２ ΔH = 131.3 kj / mol of H ２ By blowing in O, 1 kmole of CO and 1 kmole of H ２This generates CO2, which contributes to ensuring sufficient gas volume in the blast furnace. However, since the above reaction is an endothermic reaction of 131.3 kJ / mol, injecting a large amount of steam will result in a drop in the temperature before the tuyere. Therefore, the steam and recycled CO gas to be injected into the tuyere are heated to a high temperature of over 1000°C using an existing hot stove and then injected through the tuyere.

[0032] In the oxygen operation of Figure 3, the pig iron production amount of 66.62 kg (iron content 63.62 kg) is produced, which is the same as the base operation of Figure 1, and Yk moles of carbon are charged. ２ and recycled CO gas and H ２ O was injected, and the gas volume in the raceway in front of the tuyere was 121 Nm ３ Recycled CO gas and H ２ The blast furnace gas (CO ) discharged from the top of the blast furnace is heated to 1200°C in the existing hot stove 2. ２ , CO, H ２ ) to CO ２ The gas separation and recovery device 3 ２ The entire amount of CO is separated and recovered. ２ After separation (CO, H ２ ) Gas to H ２ The gas separation and recovery device 5 ２ Separate and collect. ２ A part of the CO gas after separation and recovery is recovered as CO gas. ２ The total amount of gas and CO gas is the amount of gas equivalent to the amount of carbon charged. ２ The total amount of CO gas and the amount of CO gas is recovered. The remaining CO gas is recycled as water vapor H ２ It is heated together with O in a hot air furnace 5 and blown in through the tuyere.

[0033] (Thermochemical calculation concept using Hess's law) Regardless of the course of reactions that occur in a blast furnace, it is possible to calculate the heat of a blast furnace as long as the final heat and material balance of the input and output of the blast furnace is known (Hess's law). Using this law, we will consider the case where heated steam is injected into the blast furnace tuyere.

[0034] (Reason for considering the injection of 0.8kmol of heated steam) ２　 According to the injection experiment (COURSE50), the hydrogen reduction rate increases with hydrogen injection, but the direct reduction rate decreases accordingly (Nippon Steel Technical Report No. 417, 12m ３ Test blast furnace report). 277 Nm ３ / tpig's H ２ It has been reported that the direct reduction rate is reduced to about 15%, half of the original amount. When 0.8 kmol of heated steam is injected into a blast furnace, 0.8 kmol of H and 0.8 kmol of CO are generated by the water-gas reaction in front of the tuyere (H ２ O + C → H ２ + CO). Therefore, in the case of 0.8 kmol steam injection at a pig iron production of 66.62 kg, H ２ The blowing amount is 269 Nm ３ / tpig. 12m ３ H at the test blast furnace ２ This is equivalent to the injection amount. Therefore, we will consider the case where 0.8 kmoles of heated steam is injected. In Figure 3, we will consider the case where iron with the same iron content of 63.62 kg as in base operation is produced. In terms of material balance, if x kmoles of oxygen are injected into the tuyere, the inputs to the blast furnace 1 are x kmoles of oxygen, Y kmoles of carbon, and 0.8 kmoles of steam. There are two unknown quantities: the carbon charge Y kmoles and x kmoles of oxygen injected into the tuyere. The heat balance is calculated from the thermochemical heat of formation. 0.5Y kmoles C is the CO ２ The remaining 0.5Yk moles of C contributes 110.5 kJ / mol of heat to the blast furnace as CO. The entire amount of 0.8 kmoles of steam blown into the tuyere is decomposed in front of the tuyere to form CO and H. ２ However, (H ２ O + C → H ２ +CO), H ２　 If the gas utilization rate is 50%, half of the gas (0.4 kmoles) will combine with the oxygen in the ore inside the blast furnace and return to steam, so the heat absorbed by the steam injection is 0.4 kmoles. Taking into account the heat input to the blast furnace due to the heating of the steam and recycled CO to 1200°C, the heat balance of the entire blast furnace will be examined. The details will be discussed below.

[0035] (From the oxygen balance, the relational expression between the carbon charge amount Y and the amount of oxygen blown into the tuyere x is derived.) From the oxygen balance, which is a material balance, formula A is derived, which shows the relationship between the charged carbon Yk moles and the oxygen xk moles blown in from the tuyere. The oxygen balance in the blast furnace is as follows: (1) Oxygen at the top of the furnace Explanation (1) Yk moles of C charged into the blast furnace are converted into CO in the furnace. ２ The remaining 50% becomes CO. 0.8 kmoles of steam injected from the tuyere becomes H ２ 0+C=H ２ +CO reaction produces 0.4 kmol of H ２ and is recovered, and the remaining 0.4 kmole is water H ２ It is discharged as O. (2) Oxygen taken from the charged ore: 0.8522 kmoles. See paragraph "0013" (3) Oxygen introduced through the tuyere: x kmoles + 0.2 kmoles. 0.4 kmoles is the kmoles of oxygen that entered from 0.8 kmoles of steam. Explanation The sum of x kmoles of oxygen blown into the tuyere and 0.4 kmoles of oxygen contained in 0.8 kmoles of steam is blown into the tuyere. (4) Balance The oxygen discharged from the furnace top is the sum of the oxygen from the ore and the oxygen blown into the tuyere. 0.75Y + 0.2 = 0.8522 + x + 0.4 In summary, 0.75Y - x = 1.052...Equation A Formula A is obtained from the relationship between the amount of carbon charged and the amount of oxygen blown into the tuyere.

[0036] (Calculate the amount of CO recycled to the tuyere.) Amount of CO recycled to the tuyere: 85.16 - 44.8 x Explanation (1) Amount of gas before the tuyere: When steam is injected, the amount of gas generated before the tuyere is 121 Nm3, the same as during base operation. ３ The amount of CO to be recycled is calculated so that the gas volume is 21 Nm3. ３ C → CO combustion by 42 Nm ３ and nitrogen 79 Nm ３ Total: 121 Nm ３ (2) C combustion before the tuyere: 2x x 22,4 = 44.8 x Nm ３ ← (2C + O ２ = 2CO) (3) CO generated by blowing 0.8 kmol of steam: 17.92 Nm ３←22.4 × 0.8 (4) H generated by blowing in 0.8 kmol of steam ２ ; 17.92 Nm ３ ←22.4 x 0.8 (5) The amount of CO to be recycled is 85.16 - 44.8 x Explanation: 121 - 44.8 x - 17.92 - 17.92

[0037] (Heat requirement for the entire blast furnace) The same amount of iron as in base operation, 63.62 kg, is produced, and the heat requirement for the entire blast furnace is 177.5 x 10 ３ (1) The heat input from the combustion of C is 60.2Y × 10 ３ Explanation: The charged Yk moles of carbon is CO ２ 50% and CO gas 50%. ２ exotherm; 0.5Y x 393.5 kj / mol x 0.239 Cal / j x 10 ３ Heat release of CO: 0.5Y x 110.5 kj / mol x 0.239 Cal / j x 10 ３ From the sum of the heat generated by the above formula, the heat input due to the combustion of C is 60.2Y x 10 ３ kcal is obtained. Here, C to CO ２ The heat of combustion is the chemical reaction C + O ２ =CO ２ , ΔH = -393.5 kj / mol. C + 1 / 2O ２ = CO, ΔH = -110.5 kj / mol. The standard heat of gas formation ΔH is from Basic Chemistry 21st Edition (Shokabo), p. 132. 1j = 0.239 cal. (2) H ２ Heat of reaction of O 23.12 x 10 ３ 0.8 kmol of water vapor (heat of formation: -241.8 kJ / mol) became 0.4 kmol of water vapor at the top of the furnace and was discharged outside the furnace. 0.8 kmol H ２ O → 0.4 kmol H ２ O ΔH=((-0.4×241.8-(-0.8×241.8))×0.239=23.12×10 ３ kcal (3) Heat input from heating recycled CO to 1200°C: (35.13-18.48x) x 10 ３kcal Explanation: (85.16 - 44.8 x) / 22.4 x 28 x 0.275 x 1200°C Amount of recycled CO gas Molecular weight of CO Heating to 1200°C (4) Heat input by heating the injected steam to 1200°C: 9.05 x 10 ３ kcal Explanation: 0.8 x 18 x 0.524 x 1200°C (5) Total heat input: 60.2Y x 10 ３ kcal - 18.48x + 21.06 (6) Balance: The iron production is 63.62 kg, the same as in the base operation. The iron production is 177.5 x 10 ３ kcal is required (see paragraph "0018"). 60.2Y - 18.48x + 21.06 = 177.5, so (60.2Y - 18.48x) x 10 ３ kcal=156.44×10 ３ By combining equation A, which shows the oxygen balance, and equation B, which shows the overall balance of the blast furnace, we get Y = 2.956 kmol and x = 1.165 kmol.

[0038] (Ensuring heat quantity in the lower part of the furnace) In a blast furnace, it is important to ensure not only the heat quantity of the entire blast furnace but also the heat quantity in the lower part of the furnace. In the blast furnace 1 in Figure 3, iron ore is charged from the top of the furnace, heated and reduced as it descends inside the furnace, and finally, high-temperature molten pig iron is discharged from the lower part of the furnace. By ensuring the heat quantity in the lower part of the furnace, the temperature of the molten pig iron flowing out from the lower part of the furnace is ensured. As an index of the heat quantity in the lower part of the furnace, the target is a tuyere raceway temperature Tf of 2000°C to 2300°C. In this calculation, the amount of CO gas generated in the raceway in front of the tuyere is set to 121 Nm3, the same as in conventional operation. ３ When this is the case, the temperature Tf of the raceway before the tuyere is calculated from the heat quantity of the gas entering and leaving the raceway before the tuyere.

[0039] (Heat input to the raceway before the tuyere) (1) The heat input due to the combustion of C to CO before the tuyere is 61.53 × 10 ３ kcal. Explanation: 1.165 x 2 x 110.5 x 0.239 x 10 ３ The oxygen blown into the tuyere is 1.165 kmol, and 2 moles of CO are generated from 1 mole of oxygen (2C + O ２= 2CO). The heat of CO combustion of C is 110.5 kj / mol (the heat of CO formation is ΔH = -110.5 kj / mol). (2) Sensible heat of recycled CO injected into the tuyere: 13.60 x 10 ３ kcal. Explanation: Substitute x = 1.165 into (85.16 - 44.8x) / 22.4 x 28 x 0.275 x 1200°C. (3) The heat capacity of the carbon entering the raceway before the tuyere due to the combustion of C is 20.97 x 10 ３ kcal. Explanation: 1.165 x 2 x 6 x 2000°C x 0.75 The carbon entering the pre-tuyere raceway from above is heated and has heat capacity. The carbon temperature entering the pre-tuyere raceway is set to 0.75 times the pre-tuyere raceway temperature Tf (RAM formula). 1.165 is the O injected into the tuyere. ２ The amount, 6 cal / kmol, is the specific heat of carbon at 2000°C, and the raceway temperature before the tuyere, Tf, is assumed to be 2000°C. (4) Sensible heat brought in by the heated steam: 9.056 x 10 ３ kcal. Explanation: The amount of heat generated by injecting 0.8 kmoles of steam into the tuyere is 0.8 x 18 x 0.524 x 1200°C. The molecular weight of the steam is 1200°C. (5) The amount of heat brought into the raceway by C reacting with the injected steam is 7.2 x 10 ３ kcal Explanation 0.8 x 6 x 2000°C x 0.75 (6) Heat of reaction in the steam raceway: 25.10 x 10 ３ It is an endothermic reaction of kcal. ２ O+C=H ２ +CO ΔH=25.10×10 ３ kcal -241.8 -110.5 ΔH=(-110.5-(-241.8))×0.239=31.38×10 ３ kcal When 0.8 kmoles of steam is blown in, the ３ kcal endotherm (7) Total heat input: 87.26 x 10 ３ kcal The total heat input to the raceway in front of the tuyere is 87.26 x 10 ３ kcal.

[0040] (Heat capacity of gas exiting the raceway) (1) The heat capacity of the gas exiting the raceway is 43.11 Tf x 10 ３ kcal. Explanation: CO gas emitted: 121 - 17.92 = 103.1 Nm ３ Heat capacity of exhausted CO gas: 103.1 / 22.4 x 28 x 0.288 x Tf = 37.11Tf 0.288 is the specific heat of CO at 2000°C when Tf is assumed to be 2000°C. ２ Gas: 0.8 x 2 kg x 3.743 x Tf = 5.99 Tf. 3.743 is the H gas when Tf is assumed to be 2000°C. ２ Specific heat capacity of gas at 2000°C Total heat capacity of gas: 43.11 Tf

[0041] (2) Raceway temperature Tf: 2024°C Explanation: Heat input to the raceway = 87.26 x 10 from the heat capacity of the gas exiting the raceway ３ kcal=43.11Tf

[0042] (Coke ratio) Gasification C charge = 35.47 kg (2.956 kmole x 12) Gasification coke = 39.41 kg (35.47 / 0.9... Ash 10% in coke) Gasification coke ratio = 591.6 kg / tpig (39.41 / 66.62 kg ← pig amount) Coke ratio = 636.6 kg / tpig (591.6 + 45 ← C in pig)

[0043] (Gas volume before tuyere) H ２ ;17.92Nm ３ H ２ O+C=H ２ +CO H ２ Reaction with O and CO: 17.92 Nm ３ CO combustion: 52.19 Nm ３ Substitute x; 1.165 into 44.8x Recycled CO; 32.97 Nm ３ Substitute 1.165 for 85.16-44.8x to get a total of 121 Nm ３ (Product gas amount) CO: 33.1 Nm ３ 2.956 kmol x 0.5 H ２ 9.0 Nm ３

[0044] (O / C of shout section) O / C of shout section = 2.4 (1500 kg / 637 kg)

[0045] (The effect of the direct reduction rate decreasing due to the injection of heated steam) As mentioned above, the H ２ According to the blowing experiment (COURSE50), 277 Nm ３ / tpig's H ２ Injection of 0.8 kmol of heated steam into the blast furnace reduces the direct reduction rate to about 15% by half. ２ and 0.8 kmole of CO is generated (H ２ O + C → H ２ +CO), 17.92Nm ３ H ２ and 17.92 Nm ３ of CO is generated. ２ If the gas utilization rate is 50%, the H generated in front of the tuyere ２ At the furnace top, 50% is H ２ O, 50% is H ２ It is discharged at 17.92 Nm before the tuyere. ３ However, the CO generation decreases due to the decrease in the direct reduction rate, and the CO gas generation at the furnace top decreases accordingly.

[0046] (CO by CO gas recycling ２ Example 3 of the present invention (Table 1) Fig. 4 shows Example 3 of the present invention. ２ This is a blast furnace operation method in which only gas is recovered. ２ and CO ２ The separated CO gas is blown into the blast furnace tuyeres, and all of it is CO ２ This is a blast furnace operation method in which the amount of O2 recovered as gas is 21 Nm3, the same as in the conventional operation of Comparative Example 1 (Fig. 1). ２ And, N ２ instead of 79 Nm ３　 The recycled CO gas is injected from the tuyere to ensure the amount of gas in the raceway before the tuyere. ２Since the CO generated from the CO2 is insufficient, it is stored in the CO2 relay tank 4 in advance. After storage, the CO2 is stored at a steady state of 79 Nm3. ３ CO gas was blown in from the tuyeres, and 121 Nm ３ Ensure the amount of CO gas before the tuyere.

[0047] (Heat requirement for the entire blast furnace) 79 Nm ３ Consider the overall heat balance of blast furnace operation when CO is injected through the tuyere. ２ and CO gas. Unused CO gas is recycled many times and blown into the blast furnace through the tuyere, ２ Therefore, all of the Yk moles of carbon charged are converted into CO ２　 This is true even if the CO gas concentration in the furnace increases and the CO gas utilization rate increases. ２ Recycle instead of 79Nm ３ The amount of CO gas is N ２ It can be considered that there is no reaction in the furnace, just like gas. The same amount of iron as in base operation, 63.62 kg, is produced, and the heat required for the entire blast furnace is 177.5 x 10 ３ kcal (see paragraph "0018"), the required carbon amount Yk moles is calculated. Since a decrease in the temperature before the tuyere is expected, the recycled CO ３ is heated to 1000°C. (1) The heat input due to the combustion of C is 94.05Y x 10 ３ kcal. Explanation: CO ２ Y x 393.5 kJ / mol x 0.239 Cal / j x 10 ３ The charged Yk moles of carbon generates Yk moles of CO in the furnace as blast furnace gas, and by recycling, Yk moles of CO ２ Gas is recovered. C to CO ２ The heat generated by combustion is the chemical reaction C + O ２ =CO ２ , ΔH = -393.5 kj / mol. C + 1 / 2O ２ = CO, ΔH = -110.5 kj / mol. The standard heat of gas formation ΔH is from Basic Chemistry 21st Edition (Shokabo), p. 132. 1j = 0.239 cal.

[0048] (2) The sensible heat of the CO gas injected through the tuyere is 26.66 x 10 ３ kcal. Explanation: 79 / 22.4 x 28 kg x 0.270 kcal / kg x 1000°C. 79 Nm3 of CO is heated to 1000°C. 28 kg is the molecular weight of CO (kg / kmol), and 0.270 kcal / kg is the specific heat of CO at 1000°C. (3) The total heat input is 94.05 Y x 10 ３ kcal+26.66×10 ３ kcal.

[0049] The iron production is 63.62 kg, the same as the base operation. ３ kcal is required (see paragraph "0018"). Therefore, 94.05Y x 10 ３ kcal+26.66×10 ３ kcal=177.5×10 ３ kcal From the above formula, we obtain Y = 1.604 kmole. If 1.604 kmole of carbon is charged, the heat capacity of the entire blast furnace can be secured.

[0050] (Heat quantity required in the lower part of the furnace) In a blast furnace, it is important to ensure not only the heat quantity of the entire blast furnace but also the heat quantity in the lower part of the furnace. In the blast furnace 1 in Figure 2, iron ore is charged from the top of the furnace, heated and reduced as it descends inside the furnace, and finally, high-temperature molten pig iron is discharged from the lower part of the furnace. By ensuring the heat quantity in the lower part of the furnace, the temperature of the molten pig iron flowing out from the lower part of the furnace is ensured. As an index of the heat quantity in the lower part of the furnace, the target is a tuyere raceway temperature Tf of 12,000°C to 2,300°C. In this calculation, the amount of CO gas generated in the raceway in front of the tuyere is set to 121 Nm3, the same as in conventional operation. ３ When this is the case, the temperature Tf of the raceway before the tuyere is calculated from the heat quantity of the gas entering and leaving the raceway before the tuyere.

[0051] (Heat input to the raceway before the tuyere) (1) The heat input due to the combustion of C to CO before the tuyere is 49.52 × 10 ３ kcal. Explanation: 21 / 22.4 x 2 x 110.5 x 0.239 x 10 ３ kcal 21 Nm injected into the tuyere ３of oxygen combusts to 2 kmoles of CO (2C + O ２ = 2CO). The heat of CO combustion in C is 110.5 kj / mol (the heat of CO formation is ΔH = -110.5 kj / mol). (2) The sensible heat of CO gas injected into the tuyere is 26.66 x 10 ３ kcal. Explanation: 79 / 22.4 x 28 kg x 0.270 kcal / kg x 1000°C. 79 Nm ３ of CO is heated to 1000°C. 28 kg is the molecular weight of CO (kg / kmol), and 0.270 kcal / kg is the specific heat of CO at 1000°C. (4) The heat capacity of the carbon entering the pre-tuyere raceway is 17.72 x 10 ３ kcal. Explanation: 21 / 22.4 x 2 x 6 x 2100°C x 0.75 The carbon entering the pre-tuyere raceway from above is heated and has heat capacity. The temperature of the carbon entering the pre-tuyere raceway is set to 0.75 times the pre-tuyere raceway temperature Tf (RAM formula). 6 cal / K mol is the specific heat of carbon at 2100°C, and the pre-tuyere raceway temperature Tf is assumed to be 2100°C. One mole of oxygen reacts with two C atoms. 2C + O ２ = 2CO (6) The total heat input is 93.9 x 10 ３ It becomes kcal.

[0052] (Heat capacity of gas exiting the raceway) (1) The heat capacity of CO2 exiting the raceway is 43.71 Tf × 10 ３ kcal. Explanation: 121 / 22.4 x 28 x 0.289 x Tf x 10 ３ kcal 121 is tuyere injection 21 Nm ３ CO generated by oxygen and recycled 79 Nm ３ Total CO. 28 is the molecular weight of CO in kg, and 0.289 is the specific heat of CO in kcal / kg°C assuming Tf is 2100°C. (Raceway temperature) From the heat balance, it is 93.9 x 10 ３ kcal=43.71Tf×10 ３ kcal Tf=2148℃

[0053] (Gas volume before tuyere) Tuyere injection O ２ CO = 42 Nm ３Tuyere-injected recycled CO gas 79 Nm ３ Total: 121Nm ３ (O to the tuyere ２ Injection amount) 21 Nm ３ (Gas amount before the tuyere) CO: 42 Nm ３ Recycled CO: 79 Nm ３ Total: 121Nm ３ (Product gas volume) CO ２ ; 35.9 Nm ３ 1.604 kmol

[0054] (Coke ratio) Gasification C charge Y = 19.25 kg (1.604 kmole x 12) Gasification coke = 21.39 kg (19.25 / 0.9... Ash in coke 10%) Gasification coke ratio = 321 kg / tpig (21.39 / 66.62 kg ← pig amount) Coke ratio = 366 kg / tpig (321 + 45 ← C in pig)

[0055] (O / C of shout section) O / C of shout section = 4.1 (1500 kg / 366 kg)

[0056]

[0057] (Summary of Table 1) 1. Comparative Example (Conventional Blast Furnace) (1) To make the calculation easier to understand, the conventional blast furnace was set at a blast speed of 100 Nm 3 The calculation was based on all-coke operation per ton and compared with CO gas recycling operation. The CO gas utilization rate was set at 50%. (2) In all-coke operation, the temperature before the tuyere reaches a high temperature of 2,356°C, but in actual operation, pulverized coal is injected, and if 200 kg / t is injected, the temperature becomes 2,084°C. 2. Invention Example 1 (N by CO gas recycling) ２ (1) Method for producing free CO gas ２ In order to produce blast furnace CO gas that does not contain CO, oxygen operation is performed instead of air blast. ２ Instead of CO gas 79 Nm ３ (2) The charged Yk moles of carbon are recycled at the furnace top, and 50% is CO ２ (3) The gas heating in Example 1 is calculated as O ２Since the recycled gas is not heated and only the recycled gas is heated, the heat input is reduced compared to conventional operation, and the coke ratio is slightly higher. 3. Example 2 (Operation with 0.8 kmol of heated steam injected) (1) To produce blast furnace gas that does not contain N2, oxygen operation is performed instead of air blowing. Then, to produce H2, 0.8 kmol of heated steam at 1200°C is injected from the tuyeres, and 9 Nm of hydrogen is blown. 3 and CO gas 33 Nm without N2 ３ (2) The injected steam decomposes before the tuyere and absorbs heat. Due to these factors, the coke rate increases to 637 kg / tpig. However, the increase in coke rate increases the amount of useful new gases of H2 and CO. (3) When 0.8 kmole of steam is injected, 0.8 kmole of H2 and 0.8 kmole of CO are generated before the tuyere (H2O + C → H2 + CO). As a result, the recycled CO gas is 33 Nm ３ The gas generation volume before the tuyere will be 121 Nm3, which is the same as in conventional operation. (4) The new gases H2 and CO gas will be used for synthetic chemical CO gas, so CO2 emissions from steelworks, etc. will be reduced by 38% compared to conventional operation. (54-33) / 53) (5) The temperature before the tuyere, Tf, will be 2024°C, and the gas generation volume before the tuyere will be 121 Nm3. ３ The shaft O / C is 2.4, which is smaller than that of a conventional blast furnace. This lowers the hurdle for blast furnace operation. 4. Invention Example 4 (CO reduction by CO gas recycling) ２ Gas production method) (1) All CO generated in the furnace is recycled to the tuyere, and CO ２ This is an operation to replace pulverized coal with CO2 recycle gas. The operating level of a coke ratio of 366 kg / tpig and a shout section O / C of 4.1 is almost the same as the current operating level of pulverized coal injection of 150 kg / tpig, and there is no difficulty in operation. By recycling CO2 gas, CO2 ２ can be reduced by 33%.

[0058] (In conventional blast furnaces, CO and CO from blast furnace gas ２ and N ２ From the gas mixture ２ (Produces free CO) → Figure 5 Invention Example 5 Table 1 In industry, carbon is burned with air, so it contains N2, and N ２The generation of CO gas that does not contain N is small. ２ If CO could be separated and captured from ２ Under the same operating conditions as conventional blast furnaces, a large amount of N can be produced cheaply without using precious H2. ２ It is possible to provide a CO gas that does not contain CO.

[0059] First, CCS (CO ２ and CO separation) by amine absorption solution ２ CO gas, N ２ The gas is neutral and therefore not absorbed by the amine absorbent.

[0060] CO ２ CO gas and N after separation ２ The gas mixture is subjected to pressure swing adsorption (PSA) to adsorb CO onto an adsorbent, and N ２ CO gas and N are separated and collected by passing through the ２ The gases have very similar physical and chemical properties. The size (Å) is 3.76 Å for CO and 3.76 Å for N. ２ Since the particle size is 3.64 Å, it is difficult to make the adsorbent for PSA highly functional at the molecular level using porous materials such as zeolite and activated carbon, which are commonly used, and therefore they are unsuitable. The adsorbent should be one that can be made highly functional at the molecular level. (1) PSA method using carbon molecular sieves (CMS): A highly reliable method that has been used for a long time. (2) Adsorption method using porous metal complexes (PCP): A highly efficient method based on the latest research results. (3) NaY type zeolite (NA ２ O.Al ２ There is an adsorption method using SiO3.5SiO2.

[0061] CO gas and N ２ The boiling point of the gas is -192°C for CO and -192°C for N ２ is -196°C, so CO and N ２ can also be separated.

[0062] Effects of the Invention: CO gas in blast furnace gas can be used as a raw material for synthetic fuel without changing the operating conditions of the conventional blast furnace. Conventional hot air blast and pulverized coal injection are carried out, and the fuel ratio, etc. are the same as in conventional operation.

[0063] (Quality control of CO gas for synthetic fuel) The quality of CO gas used in FT synthesis must be as follows: (1) High purity CO (95% or more). (2) Extremely low catalyst toxic components such as sulfur and water. (3) Low CO2 and CH ４ (4) H ２ The H / CO ratio must be appropriate (approximately 2:1). In the FT process, sulfur is a catalyst poison and significantly reduces the activity of the catalyst. ２ The content of sulfur compounds in blast furnace gas (such as sulphur) must be 0.1 ppm or less. The concentration of sulfur compounds in blast furnace gas is low, generally around 1 to 10 ppm, but this is insufficient and desulphurisation is required. In the pre-treatment process for FT synthesis, quality control is carried out by appropriately combining gas purification technologies (adsorption, membrane separation, chemical reaction, etc.).

[0064] (CO ２ (Responsibility for emissions) Carbon offsetting involves ２ Responsibility for emissions is usually borne by the end user who actually emitted the gas. Under the international standard (Greenhouse Gas Protocol), end users are responsible for emissions. However, ２ This depends on the contract with the supply chain, such as the steel company that provides the CO2-free gas and the oil refinery that provides the synthetic fuel, but the end user of the synthetic fuel is usually required to take responsibility for carbon offsetting.

[0065] In the blast furnace, CO ２ By recycling the CO gas after separation and removal, N ２ It is possible to produce CO2-free gas and provide it as a raw material for synthetic fuel (e-fuel). By blowing in heated steam, it is also possible to produce hydrogen. ２ By recycling the CO gas after separation and removal, ２ Gas emissions can be reduced.

[0066] 1 Blast furnace 2 Hot stove 3 CO ２ Gas removal device 4 Tuyere-injected CO gas relay tank 5 Hydrogen separation device 6 CO separation device

Claims

1. In a blast furnace, a process for producing CO gas for synthetic fuel without N2, characterized in that oxygen is blown from tuyeres instead of air, CO2 gas is separated and recovered from the blast furnace gas discharged from the top of the blast furnace, a part of the CO gas after CO2 separation and removal is recovered, and the remaining CO gas is blown from the blast furnace tuyeres as recycled CO gas, and the gas generation amount in front of the tuyeres is made equivalent to that of a blast furnace with normal air blowing.

2. In a blast furnace, a process for producing CO gas for synthetic fuel without N2 and hydrogen, characterized in that oxygen is blown from tuyeres instead of air, and further, steam and recycled CO gas are blown from the tuyeres, CO2 gas is separated and recovered from the blast furnace gas discharged from the top of the blast furnace, H2 gas is separated and recovered from the mixed gas of CO gas and H2 gas after CO2 separation, a part of the CO gas after H2 gas separation is recovered, the remaining CO gas after a part of the CO gas is recovered is used as recycled CO gas, heated together with steam and blown from the blast furnace tuyeres, and the gas generation amount in front of the tuyeres is made equivalent to that of a blast furnace with normal air blowing.

3. In a blast furnace, a process for producing CO2 gas, characterized in that oxygen is blown from tuyeres instead of air, CO2 gas is separated and recovered from the blast furnace gas discharged from the top of the blast furnace, and all of the CO gas after CO2 separation and recovery is recycled and blown from the blast furnace tuyeres, and the gas generation amount in front of the tuyeres is made equivalent to that of a blast furnace with normal air blowing.

4. A method for producing CO gas for synthetic fuel without N2, in a blast furnace with air blowing, wherein CO2 gas is separated and recovered from the mixed gas of CO, CO2 and N2 discharged from the top of the blast furnace, CO is separated and recovered from the mixed gas of CO and N2 after CO2 separation and recovery.

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