Preparation method of gas-based shaft furnace reducing gas

Abstract

The invention discloses a gas-based shaft furnace reducing gas preparation method, and belongs to the field of direct reduction iron. According to the method, the components of the raw material gas are adjusted by adding another gas into the raw material gas, and the H2 / CO value in the synthesis gas generated by the non-catalytic partial oxidation reaction of the raw material gas after the components are adjusted and pure oxygen is smaller than the H2 / CO value in the synthesis gas generated by the non-catalytic partial oxidation reaction of the raw material gas before the components are adjusted and the pure oxygen; and at least part of CO2-removed furnace top purified coal gas of the gas-based shaft furnace is mixed with synthesis gas, and the mixed gas serves as gas-based shaft furnace reducing gas. The method solves the problems of high oxidation component content of the reducing gas and carbon deposition in heating of the top gas when the non-catalytic partial oxidation method is used for preparing the reducing gas of the gas-based shaft furnace, reduces the consumption of the feed gas and improves the economic benefit.

Description

Technical Field

[0001] The present invention belongs to the field of hydrogen metallurgy, and particularly relates to a method for preparing reducing gas for a gas-based shaft furnace. Background Art

[0002] As a technology of green metallurgy, the gas-based shaft furnace has received attention and admiration from the global steel industry. However, due to resource limitations, there is a lack of natural gas for gas-based shaft furnaces in China, which has restricted the development of this technology in China. Therefore, industry experts and technicians in China have begun to consider using industrial by-products such as coke oven gas, pyrolysis gas, and semi-coke gas, which are relatively abundant in China, as the gas source for gas-based shaft furnaces. These gases contain rich CH4 and H2 components, but due to factors such as complex gas composition and high impurity content, no technology that is both economically and technically feasible has been developed. Currently, the industry generally believes that the non-catalytic partial oxidation technology can reduce the purification investment of gas sources such as coke oven gas according to the characteristics of domestic gas sources, and relevant patents have been applied for. For example, the patent application number is 202010762774.3. This patent uses the non-catalytic partial oxidation method to prepare reducing gas from coke oven gas, solving the problem of complex purification process and large investment due to high impurity content in coke oven gas. However, during the process of heat exchange of the gas-based shaft furnace top gas in the heat exchanger to obtain hot reducing gas at a temperature of 500-950°C, carbon deposition will occur. As is well known, carbon deposition affects the stable operation of production. However, this patent does not mention the occurrence of carbon deposition and the solution to carbon deposition; another example is the patent application number 202110960672.7. This patent uses a non-catalytic pure oxygen reforming furnace for the raw material gas and a partial oxidation furnace for heating the gas-based shaft furnace top gas. Although it avoids carbon deposition in the heating of the top gas, it increases the oxidation components in the reducing gas, making the quality of the reducing gas unable to meet the requirements of the gas-based shaft furnace. To sum up, using the non-catalytic partial oxidation technology to prepare reducing gas for gas-based shaft furnaces can solve the problems of complex purification process and large investment in raw material gases such as coke oven gas, but there are still the following problems: (1) Since the technology of preparing reducing gas by non-catalytic partial oxidation is still in its infancy, this technology involves knowledge in both the chemical engineering and metallurgy fields. The metallurgy industry lacks the understanding of the high oxidation components (H2O + CO2) in the syngas prepared by non-catalytic partial oxidation technology, and the chemical engineering industry also lacks the understanding of the strict control of oxidation components in the reducing gas for gas-based shaft furnaces. Therefore, the technical solutions reported by technicians in both industries do not solve the problem of high oxidation components in the syngas prepared by non-catalytic partial oxidation, which is not suitable as reducing gas. Therefore, the patent solutions lack practicality; (2) The gas-based shaft furnace top gas is rich in CO gas. When it is externally heated above 400°C, carbon deposition occurs, affecting the stable operation of production. Therefore, the technical solution of externally heating the gas-based shaft furnace top gas above 400°C is also not feasible. Summary of the Invention

[0003] However, to solve the above technical problems, the present invention provides a method for preparing reducing gas for a gas-based shaft furnace.

[0004] The object of the present invention is to simultaneously achieve the following through the solution of the present invention:

[0005] i) Avoid the problem of carbon deposition caused by the heating of the top gas in the gas-based shaft furnace in the prior art.

[0006] ii) Improve the quality of the reducing gas prepared by the non-catalytic partial oxidation process, and solve the problem that the oxidation component in the high-temperature reducing gas produced by the gas-based shaft furnace using the non-catalytic partial oxidation process is high and is not suitable as the reducing gas for the gas-based shaft furnace.

[0007] iii) Maximize the recycling of the top gas of the gas-based shaft furnace to reduce the consumption of raw material gas and achieve the purpose of reducing the gas source cost.

[0008] Other objects of the present invention will be pointed out later or will be obvious to those skilled in the art.

[0009] To achieve this object, the present invention adopts the following technical solutions:

[0010] A method for preparing a reducing gas for a gas-based shaft furnace, wherein the main components of the raw material gas are CH4 and hydrogen, and a non-catalytic partial oxidation furnace is used for preparing the reducing gas, including the following steps: (1) Adjust the composition of the raw material gas; (2) The gas after adjusting the composition undergoes a non-catalytic partial oxidation reaction with pure oxygen to generate syngas; (3) After adding H2 and / or CO gas to the syngas, it becomes the reducing gas for the gas-based shaft furnace; any one of the following three solutions is adopted to implement the above three steps:

[0011] Solution 1: By adding another gas to the raw material gas, adjust the composition of the raw material gas. The H2 / CO value in the syngas generated by the non-catalytic partial oxidation reaction of the raw material gas after adjusting the composition with pure oxygen is less than the H2 / CO value in the syngas generated by the non-catalytic partial oxidation reaction of the raw material gas before adjusting the composition. Mix at least part of the top purified gas of the gas-based shaft furnace after CO2 removal with the syngas, and the mixed gas is used as the reducing gas for the gas-based shaft furnace;

[0012] Solution 2: Mix at least part of the top purified gas of the gas-based shaft furnace after CO2 removal with the raw material gas to form a mixed gas, and the mixed gas is the raw material gas after adjusting the composition. The raw material gas after adjusting the composition undergoes a non-catalytic partial oxidation reaction with pure oxygen to generate syngas. After heating hydrogen, mix it with the syngas to become the reducing gas for the gas-based shaft furnace;

[0013] Solution 3: The feed gas consists of two types. One has a main component of CH4, and the other has a main component of hydrogen. At least part of the purified gas from the top of the gas-based shaft furnace is mixed with the feed gas with a main component of CH4 to form a mixed gas, which is the feed gas after adjusting the composition. The feed gas after adjusting the composition undergoes a non-catalytic partial oxidation reaction with pure oxygen to generate syngas. The feed gas with a main component of hydrogen is heated and then mixed with the syngas to form the reducing gas for the gas-based shaft furnace.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] A. In Solution 1 of the present invention, by adding another gas to the feed gas to adjust the composition of the feed gas, the H2 / CO ratio of the syngas generated by non-catalytic partial oxidation is reduced, and further the temperature of the reducing gas required to enter the gas-based shaft furnace is reduced; and because the temperature of the reducing gas required to enter the gas-based shaft furnace is reduced, the purpose of mixing more purified gas from the top of the gas-based shaft furnace into the syngas is achieved; as the amount of purified gas from the top of the gas-based shaft furnace mixed into the syngas increases, the consumption of the feed gas is smaller (more economical), and since the oxidizing components in the purified gas from the top of the gas-based shaft furnace are extremely low after purification, as the amount of the purified gas from the top of the furnace mixed into the syngas increases, the quality of the reducing gas is improved, and in the solution of the present application, the purified gas from the top of the gas-based shaft furnace does not need to be externally heated between 400 and 700 °C and will not form carbon deposits. Therefore, Solution 1 of the present application can simultaneously achieve the purposes of reducing the consumption of the feed gas (improving economic benefits), improving the quality of the reducing gas, and avoiding carbon deposition in the process of preparing the reducing gas (affecting the stable operation of production).

[0016] B. In Solution 2 of the present invention, at least part of the purified gas from the top of the gas-based shaft furnace after CO2 removal is mixed with the feed gas to form a mixed gas, which is the feed gas after adjusting the composition. The purpose of adjusting the composition of the feed gas is to burn and heat the CO in the purified gas from the top of the gas-based shaft furnace by non-catalytic partial oxidation furnace, so as to solve the problem of carbon deposition between 400 and 700 °C when the purified gas from the top of the gas-based shaft furnace is heated by an external heat pipe furnace in the prior art; the purpose of heating the hydrogen and then mixing it into the syngas to form the reducing gas is to improve the quality of the reducing gas and solve the problem that the oxidation components in the high-temperature reducing gas produced by the non-catalytic partial oxidation process of the gas-based shaft furnace are high and not suitable as the reducing gas for the gas-based shaft furnace; as the amount of the purified gas from the top of the furnace mixed in increases, the consumption of the feed gas decreases (economic benefits are improved); as the amount of hydrogen mixed into the syngas increases, the quality of the reducing gas is improved; and hydrogen heating will not form carbon deposits. Therefore, Solution 2 of the present application overcomes the problems of the prior art and simultaneously achieves the purposes of reducing the consumption of the feed gas (improving economic benefits), improving the quality of the reducing gas, and avoiding carbon deposition in the process of preparing the reducing gas (affecting the stable operation of production).

[0017] C. In the third solution of the present invention, when the raw material gas with the main components of CH4 and H2 includes two types, one with the main component of CH4 and the other with the main component of hydrogen, by mixing at least part of the purified gas from the top of the gas-based shaft furnace with the raw material gas with the main component of CH4 to form a mixed gas, and the mixed gas undergoes a non-catalytic partial oxidation reaction with pure oxygen to generate syngas, for the following purposes: ① Using the non-catalytic partial oxidation furnace to burn and heat CO in the purified gas from the top of the gas-based shaft furnace to solve the problem of carbon deposition between 400 and 700 °C when the purified gas from the top of the gas-based shaft furnace is heated by an external heat pipe furnace in the prior art; ② Mixing CH4 gas into the purified gas from the top of the gas-based shaft furnace to reduce the oxidation components in the syngas; The purpose of heating the raw material gas with the main component of hydrogen and then mixing it with the syngas to form the reducing gas of the gas-based shaft furnace is to improve the quality of the reducing gas and solve the problem that the high-temperature reducing gas produced by the non-catalytic partial oxidation process in the gas-based shaft furnace has high oxidation components and is not suitable as the reducing gas of the gas-based shaft furnace; As the mixing amount of the purified gas from the top of the furnace increases, the consumption of the raw material gas decreases (economic benefits are improved); As the amount of hydrogen mixed into the syngas increases, the quality of the reducing gas improves; and no carbon deposition occurs during the heating of hydrogen. Therefore, the second solution of the present application overcomes the problems in the prior art and simultaneously achieves the purposes of reducing the consumption of the raw material gas (improving economic benefits), improving the quality of the reducing gas, and avoiding carbon deposition in the process of preparing the reducing gas (affecting the stable operation of production).

[0018] The preferred solution of the present invention is:

[0019] In the adjusted raw material gas composition of Solution 1, the ratio of the number of carbon atoms to the number of hydrogen atoms is greater than that in the raw material gas composition before adjustment.

[0020] Further, the other gas added in Solution 1 is a combustible gas containing carbon elements, and the ratio of the number of hydrogen atoms to the number of carbon atoms in the gas is less than or equal to 4.

[0021] Still further, the main component of the combustible gas containing carbon elements is a mixed gas of CH4 and CO or CO gas.

[0022] Even further, in the syngas generated after the partial oxidation reaction of the adjusted gas in Solution 1 with pure oxygen, H2 / CO = 1.15 - 1.45, preferably H2 / CO = 1.2 - 1.4.

[0023] Also further, the purified gas from the top of the gas-based shaft furnace for removing CO2 in Solution 1 is first preheated to below 400 °C, preferably below 300 °C, and then mixed into the syngas, and the temperature of the formed reducing gas is 850 - 980 °C.

[0024] In Solution 2, at least part of the hydrogen is extracted from the mixed gas.

[0025] Furthermore, the extracted hydrogen is heated and then mixed with syngas to form the reducing gas for the shaft furnace, and the quality of the reducing gas is adjusted by the amount of hydrogen extracted and mixed into the syngas.

[0026] Still further, in the second solution, the temperature of the reducing gas is 950 - 1100°C, preferably 1000 - 1100°C, and the heating temperature of hydrogen is 700 - 900°C.

[0027] In the raw material gas of each of the above solutions, the proportion of hydrogen is greater than 20%.

[0028] Compared with the prior art, the preferred solution of the present invention has the following beneficial effects:

[0029] D. In the first solution, by adjusting the composition of the raw material gas, the H2 / CO in the syngas generated by the partial oxidation reaction of the adjusted gas with pure oxygen is 1.15 - 1.45, preferably H2 / CO = 1.2 - 1.4, so as to reduce the temperature of the reducing gas entering the shaft furnace to 850 - 980°C, preferably 870 - 930°C, and finally realize mixing more purified gas at the top of the shaft furnace, achieving the purpose of the present invention.

[0030] E. When there is no suitable hydrogen raw material gas at the location of the planned construction project in the second solution, the present application adjusts the composition of the raw material gas by the method of hydrogen extraction after mixing the purified gas at the top of the shaft furnace and the raw material gas. By adjusting three parameters: the amount of H2 extracted from the raw material gas and the purified gas at the top of the shaft furnace, the amount of H2 gas mixed into the syngas, and the heating temperature of H2, the quality of the reducing gas is adjusted, achieving the purpose of further increasing the metallization rate of DRI in the shaft furnace. Description of the Drawings

[0031] Figure 1 It is the process flow diagram of the first solution of the present invention;

[0032] Figure 2 It is the process flow diagram of the second solution of the present invention;

[0033] Figure 3 It is the process flow diagram of the third solution of the present invention.

[0034] The markings in the figure are: 1 - non-catalytic partial oxidation furnace, 2 - shaft furnace, 3 - reducing gas, 4 - purified gas at the top of the shaft furnace, 5 - oxygen, 6 - gas containing carbon element, 7 - raw material gas, 8 - syngas, 9 - top gas of the furnace without CO2 removed, 10 - mixture of raw material gas and purified gas at the top of the shaft furnace, 11 - remaining gas after hydrogen extraction from the mixture of raw material gas and purified gas at the top of the shaft furnace, 12 - hydrogen extracted from the mixture formed by the raw material gas and the purified gas at the top of the shaft furnace, 21 - dust collector, 22 - carbon dioxide removal device, 23 - tubular heating furnace, 71 - gas mainly composed of CH4, 72 - gas mainly composed of H2. Detailed Embodiments

[0035] To fully understand the objectives, features, and effects of the present invention, the following detailed embodiments are provided to elaborate on the present invention in detail. However, the present invention is not limited thereto only.

[0036] Embodiment 1

[0037] Please refer to Figure 1 . The raw material gas 7 is coke oven gas, and the carbon-containing gas 6 is a mixture of CO gas extracted from converter gas and natural gas. The coke oven gas and the carbon-containing gas 6 are mixed in a certain proportion to form a mixed gas. The mixed gas and oxygen 5 undergo a partial oxidation reaction in the non-catalytic partial oxidation furnace 1 to generate syngas 8. The temperature of the syngas 8 is 1100 - 1350 °C, and H2 / CO is about 1.4. The top gas of the gas-based shaft furnace is divided into two streams after passing through the dust collector 21, namely the top gas 9 without CO2 removal and the purified top gas 4 of the gas-based shaft furnace that has been de-carbon dioxide through the carbon dioxide removal device 22 and then desulfurized (not shown in the figure). Among them, the top gas 9 without CO2 removal accounts for more than 1 / 3 of the top gas volume of the gas-based shaft furnace. The purified top gas 4 of the gas-based shaft furnace is heated to 290 - 390 °C in the tubular heating furnace 23 and then mixed with the syngas 8 to form the reducing gas 3. The temperature of the mixed reducing gas is 910 - 980 °C, and H2O + CO2 in the mixed reducing gas is 9 - 10%. The reducing gas 3 enters the gas-based shaft furnace 2.

[0038] Embodiment 2

[0039] Please refer to Figure 1 . The raw material gas 7 is coke oven gas, and the carbon-containing gas 6 is CO gas extracted from converter gas. The coke oven gas and the carbon-containing gas 6 are mixed in a certain proportion. The mixed gas and oxygen 5 undergo a partial oxidation reaction in the non-catalytic partial oxidation furnace 1 to generate syngas 8. The temperature of the syngas 8 is 1100 - 1300 °C, and H2 / CO is about 1.3. The top gas of the gas-based shaft furnace is divided into two streams after passing through the dust collector 21, namely the top gas 9 without CO2 removal and the purified top gas 4 of the gas-based shaft furnace that has been de-carbon dioxide through the carbon dioxide removal device 22 and then desulfurized (not shown in the figure). Among them, the top gas 9 without CO2 removal accounts for about 1 / 3 of the top gas volume of the gas-based shaft furnace. The purified top gas 4 of the gas-based shaft furnace is heated to 280 - 380 °C in the tubular heating furnace 23 and then mixed with the syngas 8 to form the reducing gas 3. The temperature of the mixed reducing gas is 880 - 930 °C, and H2O + CO2 in the mixed reducing gas is 8 - 9%. The reducing gas 3 enters the gas-based shaft furnace 2.

[0040] Embodiment 3

[0041] Please refer to Figure 1。The feed gas 7 is coke oven gas, and the carbon-containing gas 6 is CO gas extracted from blast furnace gas. The coke oven gas and the CO gas extracted from blast furnace gas are mixed in a certain proportion. The mixed gas and oxygen 5 undergo a partial oxidation reaction in the non-catalytic partial oxidation furnace 1 to generate syngas 8. The temperature of the syngas 8 is 1200 - 1300 °C, and H2 / CO is about 1.2. The top gas of the gas-based shaft furnace is divided into two streams after passing through the dust collector 21, namely the top gas 9 without CO2 removal and the purified top gas 4 of the gas-based shaft furnace that is desulfurized (not shown in the figure) after passing through the carbon dioxide removal device 22. Among them, the top gas 9 without CO2 removal accounts for less than 1 / 3 of the top gas volume of the gas-based shaft furnace and is used for other purposes such as fuel. The purified top gas 4 of the gas-based shaft furnace is heated to 250 - 350 °C in the tubular heating furnace 23 and then mixed with the syngas 8 to form the reducing gas 3. The temperature of the mixed reducing gas is 850 - 900 °C, and H2O + CO2 in the mixed reducing gas is 7 - 8%. The reducing gas 3 enters the gas-based shaft furnace 2.

[0042] As can be seen from the above Examples 1, 2, and 3, as the proportion of the top gas 9 without CO2 removal in the top gas volume of the gas-based shaft furnace decreases, the amount of the purified top gas 4 of the gas-based shaft furnace for recycling and mixing with the syngas 8 increases. The content of the oxidation components H2O + CO2 in the reducing gas 3 decreases from 9 - 10% to 7 - 8%, and the quality of the reducing gas is significantly improved. As the amount of the purified top gas 4 of the gas-based shaft furnace for recycling increases, the consumption of the feed gas 7 decreases, and the economic benefit is improved. Moreover, the purified top gas 4 of the gas-based shaft furnace is heated to a maximum temperature of 390 °C in the tubular heating furnace 23, and no carbon deposition occurs, solving the problem of carbon deposition that occurs when the external heating furnace is used to increase the recycling amount of the purified top gas of the gas-based shaft furnace and the heating temperature needs to be raised above 400 °C in the prior art.

[0043] Example 4

[0044] Please refer to Figure 2 。The feed gas 7 is coke oven gas. The top gas of the gas-based shaft furnace is divided into two streams after passing through the dust collector 21, namely the top gas 9 without CO2 removal and the purified top gas 4 of the gas-based shaft furnace that has CO2 removed and is then desulfurized after passing through the carbon dioxide removal device 22. Among them, the top gas 9 without CO2 removal accounts for about 25 - 35% of the top gas volume of the gas-based shaft furnace. The purified top gas 4 of the gas-based shaft furnace after CO2 removal and desulfurization is mixed with the feed gas 7 to form a mixed gas 10. The hydrogen 12 in the mixed gas 10 is extracted to the maximum extent, and the remaining gas is the gas 11 with adjusted composition. The gas 11 with adjusted composition and oxygen 5 undergo a partial oxidation reaction in the non-catalytic partial oxidation furnace 1 to generate syngas 8. The temperature of the syngas 8 is 1200 - 1350 °C. The extracted hydrogen 12 is heated to 700 - 800 °C in the tubular heating furnace 23 and then mixed with the syngas 8 to become the reducing gas 3 of the gas-based shaft furnace. The temperature of the reducing gas 3 is 950 - 1050 °C, and H2O + CO2 in the reducing gas is 8.5 - 10%. The reducing gas 3 enters the gas-based shaft furnace 2.

[0045] Example 5

[0046] Please refer to Figure 2 The raw material gas 7 is coke oven gas. After passing through the dust collector 21, the top gas of the gas-based shaft furnace is divided into two streams, namely the top gas 9 without CO2 removal and the purified top gas 4 of the gas-based shaft furnace that has been decarbonized by the decarbonization device 22 and then desulfurized (not shown in the figure). Among them, the top gas 9 without CO2 removal accounts for about 10-25% of the top gas volume of the gas-based shaft furnace and is used for other purposes such as fuel. The purified top gas 4 of the gas-based shaft furnace after decarbonization and desulfurization is mixed with the raw material gas 7 to form a mixed gas 10. The hydrogen 12 in the mixed gas 10 is extracted to the maximum extent, and the remaining gas is the gas 11 with adjusted composition. The gas 11 with adjusted composition undergoes a partial oxidation reaction with oxygen 5 in the non-catalytic partial oxidation furnace 1 to generate syngas 8, and the temperature of the syngas 8 is 1200-1350°C. The extracted hydrogen 12 is heated to 800-900°C by the tubular heating furnace 23 and then mixed with the syngas 8 to become the reducing gas 3 of the gas-based shaft furnace. The temperature of the reducing gas 3 is 950-1100°C, and H2O + CO2 = 7-8.5% in the reducing gas. The reducing gas 3 enters the gas-based shaft furnace 2.

[0047] It can be seen from Examples 4 and 5 that as the amount of the purified top gas 4 of the gas-based shaft furnace after decarbonization and desulfurization mixed into the raw material gas 7 increases, the amount of hydrogen 12 extracted from the mixed gas 10 increases, the amount of hydrogen mixed into the syngas 8 increases, the content of the oxidation components H2O + CO2 in the reducing gas 3 decreases from 8.5-10% to 7-8.5%, the quality of the reducing gas improves, the consumption of the raw material gas 7 decreases, and the economic benefit improves; no carbon deposition occurs during hydrogen heating.

[0048] Example 6

[0049] Please refer to Figure 3There are two raw material gases 7, namely, the gas 71 rich in CH4, which is abundant in the chemical industry, and the gas 72 mainly composed of H2; the top gas of the shaft furnace is divided into two streams after passing through the dust collector 21, namely, the top gas 9 without CO2 removal and the purified top gas 4 of the shaft furnace with CO2 removed after passing through the CO2 removal device 22. Among them, the top gas 9 without CO2 removal accounts for about 5-20% of the top gas volume of the shaft furnace and is used for other purposes such as fuel; the purified top gas 4 of the shaft furnace with CO2 removed is mixed with the raw material gas 71 to form a mixed gas 10. The mixed gas 10 is a gas with adjusted composition. The gas with adjusted composition undergoes a partial oxidation reaction with oxygen 5 in the non-catalytic partial oxidation furnace 1 to generate synthesis gas 8, and the temperature of the synthesis gas 8 is 900-1250°C. The hydrogen 72 is heated to 600-900°C by the tubular heating furnace 23 and then mixed with the synthesis gas 8 to become the reducing gas 3 of the shaft furnace. The temperature of the reducing gas 3 is 900-1100°C, and H2O + CO2 = 6-8% in the reducing gas. The reducing gas 3 enters the shaft furnace 2. In this embodiment, when the ratio of (raw material gas 71) / (raw material gas 71 + raw material gas 72) is less than 10%, the top gas of the shaft furnace can also not remove CO2. One part is used for other purposes such as fuel, and the other part is mixed with the raw material 71 to form a mixed gas 10.

[0050] The above are only the preferred embodiments of the present invention. Of course, those skilled in the art can make changes and modifications to the present invention. If these modifications and variations fall within the scope of the claims of the present invention and their equivalent technologies, they should be considered as the protection scope of the present invention.

Claims

1. A method for preparing reducing gas in a gas-based shaft furnace, where the main components of the raw material gas are CH4 and H2, and a non-catalytic partial oxidation furnace is used for preparing the reducing gas, characterized in that It includes the following steps: (1) Adjust the composition of the raw gas; (2) The adjusted raw gas undergoes a non-catalytic partial oxidation reaction with pure oxygen to produce syngas; (3) After adding H2 and / or CO gas to the syngas, it becomes the reducing gas for the shaft furnace. Any one of the following three schemes is adopted to implement the above three steps: Scheme 1, by adding another gas to the raw gas to adjust the composition of the raw gas, the H2 / CO value in the syngas produced by the non-catalytic partial oxidation reaction of the adjusted raw gas with pure oxygen is less than the H2 / CO value in the syngas produced by the non-catalytic partial oxidation reaction of the raw gas before composition adjustment. At least part of the top-purified gas from the shaft furnace with CO2 removed is mixed with the syngas as the reducing gas for the shaft furnace; Scheme 2, at least part of the top-purified gas from the shaft furnace with CO2 removed is mixed with the raw gas to form a mixed gas, and the mixed gas is the adjusted raw gas. The adjusted raw gas undergoes a non-catalytic partial oxidation reaction with pure oxygen to produce syngas. After heating the hydrogen, it is mixed with the syngas to become the reducing gas for the shaft furnace; Scheme 3, the raw gas includes two types. One has a main component of CH4, and the other has a main component of hydrogen. At least part of the top-purified gas from the shaft furnace is mixed with the raw gas with a main component of CH4 to form a mixed gas, and the mixed gas is the adjusted raw gas. The adjusted raw gas undergoes a non-catalytic partial oxidation reaction with pure oxygen to produce syngas. After heating the raw gas with a main component of hydrogen, it is mixed with the syngas to become the reducing gas for the shaft furnace.

2. The method for preparing reducing gas in a gas-based shaft furnace according to claim 1, characterized in that In Scheme 1, the ratio of the number of carbon atoms to the number of hydrogen atoms in the adjusted raw gas composition is greater than the ratio of the number of carbon atoms to the number of hydrogen atoms in the raw gas composition before adjustment.

3. A method for preparing reducing gas in a gas-based shaft furnace according to claim 2, characterized in that The other gas added in Scheme 1 is a combustible gas containing carbon elements, and the ratio of the number of hydrogen atoms to the number of carbon atoms in the gas is less than or equal to 4.

4. A method for preparing reducing gas in a gas-based shaft furnace according to claim 3, characterized in that The main components of the combustible gas containing carbon elements are a mixed gas of CH4 and CO or CO gas.

5. A method for preparing reducing gas in a gas-based shaft furnace according to claim 4, characterized in that In Scheme 1, the H2 / CO in the syngas produced after the partial oxidation reaction of the adjusted gas with pure oxygen is 1.15 - 1.45, preferably H2 / CO = 1.2 - 1.

4.

6. The method for preparing reducing gas in a gas-based shaft furnace according to claim 5, characterized in that In Scheme 1, the top-purified gas from the shaft furnace with CO2 removed is preheated to below 400 °C, preferably below 300 °C, and then mixed into the syngas to form the reducing gas, and the temperature of the reducing gas is 850 - 980 °C.

7. A method for preparing reducing gas in a gas-based shaft furnace according to claim 1, characterized in that In Scheme 2, at least part of the hydrogen is extracted from the mixed gas.

8. A method for preparing reducing gas for a gas-based shaft furnace according to claim 7, characterized in that The extracted hydrogen is heated and then mixed with the syngas to become the reducing gas for the shaft furnace, and the quality of the reducing gas is adjusted by the amount of hydrogen extracted and mixed into the syngas.

9. A method for preparing reducing gas in a gas-based shaft furnace according to claim 7, characterized in that In Scheme 2, the temperature of the reducing gas is 950 - 1100 °C, preferably 1000 - 1100 °C, and the heating temperature of the hydrogen is 700 - 900 °C.

10. A method for preparing reducing gas in a gas-based shaft furnace according to any one of claims 1 to 9, characterized in that The hydrogen content in the raw gas is greater than 20%.

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