System for making iron and co-producing methanol by using methane reformed gas

Abstract

The utility model belongs to the technical field of ironmaking, and particularly discloses a system for ironmaking and co-producing methanol by using methane reforming gas, which comprises a feed gas supply unit, a methane reforming reactor, a direct reduction shaft furnace, a methanol synthesis unit and a methanol separation unit, the raw material gas supply unit is used for mixing methane-rich gas and furnace top gas to serve as methane reforming raw material gas to be sent to the methane reforming reactor to be converted into high-temperature reducing gas; one part of the high-temperature reducing gas is introduced into the direct reduction shaft furnace, and the other part of the high-temperature reducing gas is used as methanol synthesis raw material gas to enter a methanol synthesis unit to be converted into methanol-rich product gas, and then the methanol separation unit is used for purification to obtain methanol and low-temperature reducing gas; methanol flows back to the shaft furnace, and low-temperature reducing gas is recycled as methanol synthesis raw material gas. By adopting the system, methanol can be co-produced while direct reduced iron is produced, and double yields of carbon sequestration and economic benefits can be realized by flexibly adjusting product distribution, so that carbon emission is greatly reduced, and even zero carbon emission is realized.

Description

Technical Field

[0001] This application relates to the field of ironmaking equipment technology, and in particular to a system for ironmaking and methanol co-production using methane reforming gas. Background Technology

[0002] Blast furnace ironmaking emits significant carbon emissions, and the advancement of dual carbon targets has led to increasing attention being paid to shaft furnace ironmaking. Hydrogen-based shaft furnaces, represented by Midrex and HYL, have been widely promoted and applied worldwide. Essentially, they utilize syngas generated from methane reforming to reduce iron ore and produce direct reduced iron. However, because CO participates in the reduction reaction and the system's internal heating relies on the combustion of fuel gases (such as natural gas and top gas), it still results in relatively high levels of carbon emissions.

[0003] To address the aforementioned issues, patent CN103525966A provides a method and system for producing gas-based direct reduced iron using natural gas catalytic conversion. This system treats the furnace top gas using a decarburization method; however, the removed carbon dioxide is emitted externally, meaning that carbonaceous substances entering the system are ultimately emitted as carbon dioxide and are not converted or utilized. Furthermore, the heaters used in this system are fueled by natural gas or purified tail gas, which will increase additional carbon emissions to some extent.

[0004] Patent CN103276133A provides a method for producing direct reduced iron using the partial oxidation of natural gas. The method includes: furnace top gas discharged from a vertical shaft furnace is washed with water, compressed, and divided into three parts: gas 1, gas 2, and gas 3; gas 1 is mixed with natural gas, preheated in a preheater, and then heated in a heating furnace; gas 2 is introduced into the heating furnace as fuel; the heated gas, along with oxygen and water vapor, enters a partial oxidizer for an oxidative reforming reaction to generate high-temperature reducing gas; the high-temperature reducing gas is mixed with desulfurized and decarbonized gas 3 and then introduced into the vertical shaft furnace to reduce iron oxide pellets; the iron oxide pellets are reduced to obtain direct reduced iron, which is then cooled in the cooling section of the vertical shaft furnace before being discharged. While this method can efficiently and flexibly utilize furnace top gas, it is similar to the method provided by patent CN103525966A, and also suffers from the problems of direct emission of decarbonized gas and carbon emissions from the heating furnace.

[0005] Patent CN108315523A provides a method and system for producing direct reduced iron through autothermal reforming of carbon dioxide and methane. This system recycles a portion of the carbon dioxide and uses methane and carbon dioxide to reform syngas, which can alleviate carbon emissions. However, it still cannot avoid the drawback that carbon-containing substances in the raw materials are ultimately emitted as carbon dioxide.

[0006] The above analysis clearly shows that while there are many current methods for mitigating carbon emissions from vertical shaft furnaces, none of them address the issue of carbonaceous materials ultimately being converted into carbon dioxide within the system. Based on these considerations, developing a method and system that combines vertical shaft furnace ironmaking with carbon sequestration technology would be highly effective in reducing carbon emissions. Utility Model Content

[0007] In view of the shortcomings of the prior art described above, the purpose of this application is to provide a system for co-producing methanol from ironmaking using methane reforming gas. This system can recycle carbon dioxide produced in ironmaking into carbon monoxide and convert excess carbon monoxide into liquid methanol, thereby achieving carbon sequestration. In addition, the system uses electric heating instead of burning fuel gas for heating, thus greatly reducing carbon emissions or even achieving zero carbon emissions. Furthermore, by-products can be used to improve the production efficiency of the vertical shaft furnace according to market conditions, achieving carbon sequestration while flexibly adjusting product distribution, thereby maximizing benefits.

[0008] To achieve the above and other related objectives, this application provides a system for co-producing methanol from iron using methane reforming gas, comprising a feed gas supply unit, a methane reforming reactor, a direct reduction shaft furnace, a methanol synthesis unit, and a methanol separation unit.

[0009] The feed gas supply unit is used to supply methane reforming feed gas to the methane reforming reactor. The methane reforming feed gas includes methane-rich gas and top gas from the direct reduction shaft furnace, which includes carbon dioxide and water vapor.

[0010] The methane reforming reactor is the place where the methane reforming feed gas is converted into high-temperature reducing gas through the methane reforming reaction. The high-temperature reducing gas includes carbon monoxide and hydrogen. The methane reforming reactor is connected to the direct reduction shaft furnace and is used to introduce a portion of the high-temperature reducing gas into the direct reduction shaft furnace.

[0011] The direct reduction shaft furnace is a place where iron ore is reduced to direct reduced iron and the furnace top gas is generated.

[0012] The methanol synthesis unit is a place where methanol synthesis feed gas is converted into methanol-rich product gas through a methanol synthesis reaction.

[0013] The methanol separation unit is used to purify the methanol-rich product gas to obtain methanol product and low-temperature reducing gas; the methanol separation unit is provided with a methanol outlet, which is connected to the direct reduction vertical furnace;

[0014] The methanol synthesis feed gas includes another portion of the high-temperature reducing gas and the low-temperature reducing gas.

[0015] The main process of using the system provided in this application to produce methanol from iron ore through methane reforming gas is as follows:

[0016] Methane reforming feedstock gas enters the methane reforming reactor, where it is converted into high-temperature reducing gas, primarily composed of carbon monoxide and hydrogen. A portion of this high-temperature reducing gas enters a direct reduction shaft furnace, where it reacts with iron ore from the furnace top, reducing the iron ore to direct reduced iron. The furnace top gas, primarily composed of carbon dioxide and water vapor, is then recycled back into the feedstock gas supply unit as a source of feedstock gas for methane reforming. Another portion of this high-temperature reducing gas serves as feedstock gas for methanol synthesis, entering the methanol synthesis unit where carbon monoxide, carbon dioxide, and hydrogen are converted into methanol through a methanol synthesis reaction, yielding a methanol-rich product gas. The methanol-rich product gas enters the methanol separation unit, where it is purified to separate out the methanol. A portion of the methanol can be recycled back to the direct reduction shaft furnace, where iron ore catalyzes the decomposition of methanol into carbon monoxide and hydrogen, which are then used as reducing gas in the shaft furnace for ironmaking, thereby improving the furnace's production efficiency and maximizing its benefits. Simultaneously, the methanol separation unit separates unreacted gases such as carbon monoxide, carbon dioxide, and hydrogen, which are then used as low-temperature reducing gas. This mixture is then combined with the high-temperature reducing gas to serve as raw material for methanol synthesis and reused.

[0017] Using the above methods, the carbon dioxide produced in ironmaking will not be emitted externally, but will be converted back into usable carbon monoxide as a raw material for methane reforming, thus reducing carbon emissions. At the same time, the carbon elements input from methane will eventually be converted into methanol, achieving carbon fixation while generating additional economic benefits. In addition, depending on product price fluctuations, some of the by-product methanol can be used as a means to improve the quality and efficiency of the reducing gas in the direct reduction shaft furnace, thereby maximizing economic benefits.

[0018] Furthermore, the raw material gas supply unit includes a first buffer tank, which is the place where the methane-rich gas is mixed with the top gas.

[0019] Furthermore, the bottom of the first buffer tank is provided with a condensate outlet, which is used to discharge condensate.

[0020] Furthermore, the methane reforming reactor is loaded with a first catalyst, which is the catalyst required for the methane reforming reaction; preferably, the methane reforming reactor is provided with a catalyst bed loaded with the first catalyst. The methane reforming reaction is carried out in the presence of the first catalyst.

[0021] Furthermore, the methanol synthesis unit includes a pressurizing device and a methanol synthesis reactor. The pressurizing device is used to pressurize, cool, and dehydrate the methanol synthesis feed gas. The methanol synthesis reactor is the site where the methanol synthesis feed gas is converted into the methanol-rich product gas through a methanol synthesis reaction.

[0022] Furthermore, the methanol synthesis reactor is loaded with a second catalyst, which is the catalyst required for the methanol synthesis reaction; preferably, the methanol synthesis reactor is provided with a catalyst bed loaded with the second catalyst. The methane synthesis reaction is carried out in the presence of the second catalyst.

[0023] Furthermore, the methanol synthesis unit also includes a second buffer tank, which is a place where another part of the high-temperature reducing gas is mixed with the low-temperature reducing gas and cooled to form the methanol synthesis feedstock gas.

[0024] Furthermore, the methanol separation unit includes a methanol purification device, which is used to separate methanol from the methanol-rich product gas by liquefying methanol and obtain the low-temperature reducing gas.

[0025] Furthermore, the methanol purification device is equipped with a gas outlet, which is connected to the second buffer tank. Unreacted carbon monoxide, hydrogen, carbon dioxide, etc. (i.e., the low-temperature reducing gas) are separated out and enter the second buffer tank to mix with the high-temperature reducing gas.

[0026] Furthermore, the system also includes a power supply device connected to the methane reforming reactor, used to generate heat through electricity to provide Joule heat for the methane reforming reaction. This setup ensures that the heat required for the methane reforming reaction is generated upon power supply, thus preventing additional carbon dioxide emissions from the use of fossil fuels and achieving near-zero carbon emissions.

[0027] Furthermore, the system also includes a dust removal unit, which is used to remove dust from the top gas discharged from the direct reduction shaft furnace. The dust removal unit is located between the direct reduction shaft furnace and the raw material gas supply unit. After the top gas is dusted, it is mixed with methane-rich gas.

[0028] Furthermore, the system also includes a cooler connected to both the direct reduction shaft furnace and the methanol synthesis unit. The cooler serves as a heat exchange point between the direct reduced iron produced by the direct reduction shaft furnace and the methanol synthesis feedstock gas. The direct reduced iron discharged from the furnace bottom is at a very high temperature; exchanging heat with the methanol synthesis feedstock gas cools the direct reduced iron while simultaneously heating the methanol synthesis feedstock gas to the temperature required for the methanol synthesis reaction. In this way, the heat required for methanol synthesis is provided by the hot sponge iron, eliminating the need for additional heating and achieving both waste heat recovery and cooling of the direct reduced iron.

[0029] Furthermore, the cooler is connected to the direct reduction shaft furnace, the pressurizing equipment, and the methanol synthesis reactor, respectively. The cooler serves as a heat exchange station for the direct reduced iron produced by the direct reduction shaft furnace and the methanol synthesis feed gas, which has been pressurized, cooled, and dehydrated by the pressurizing equipment. The methanol synthesis feed gas is first pressurized, cooled, and dehydrated before entering the cooler to exchange heat with the direct reduced iron, and then enters the methanol synthesis reactor for the methanol synthesis reaction. Attached Figure Description

[0030] Figure 1 The diagram shows the layout of a system for co-producing methanol from iron using methane reforming gas, as described in some embodiments of this application.

[0031] Figure 2 The diagram shows the layout of a system for co-producing methanol from iron using methane reforming gas, as described in some other embodiments of this application.

[0032] Figure 3 The diagram shows the layout of a system for co-producing methanol from iron using methane reforming gas, as described in some other embodiments of this application.

[0033] Figure 4 The diagram shows the layout of a system for co-producing methanol from iron using methane reforming gas, as described in some other embodiments of this application.

[0034] Explanation of reference numerals in the attached figures:

[0035] 1. Direct reduction shaft furnace; 2. Dust removal unit; 3. First buffer tank; 4. Methane reforming reactor; 5. Power supply equipment; 6. Cooler; 7. Second buffer tank; 8. Pressurization equipment; 9. Methanol synthesis reactor; 10. Methanol purification unit. Detailed Implementation

[0036] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0037] It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show components relevant to the present invention and are not drawn according to the actual number, shape, and size of components in implementation. In actual implementation, the form, quantity, and proportion of each component can be arbitrarily changed, and the component layout may be more complex. The structures, proportions, sizes, etc., depicted in the accompanying drawings are only for illustrative purposes to aid those skilled in the art and are not intended to limit the implementation conditions of the present invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effects and objectives of the present invention, should still fall within the scope of the technical content disclosed in the present invention. Furthermore, the terms such as "upper," "lower," "left," "right," "middle," and "one" used in this specification are only for clarity of description and are not intended to limit the scope of the present invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the present invention.

[0038] Please refer to Figure 1 One embodiment of this application provides a system for co-producing methanol from iron using methane reforming gas, including a feed gas supply unit, a methane reforming reactor 4, a direct reduction shaft furnace 1, a methanol synthesis unit, and a methanol separation unit.

[0039] The feed gas supply unit is used to supply methane reforming feed gas to the methane reforming reactor 4. The methane reforming feed gas includes methane-rich gas and top gas from the direct reduction shaft furnace 1. The top gas includes carbon dioxide and water vapor, as well as unreacted carbon monoxide and hydrogen. The methane-rich gas is, for example, one or more of natural gas, coalbed methane, shale gas, and coke oven gas, but is not limited to these.

[0040] The methane reforming reactor 4 is the place where the methane reforming feed gas is converted into high-temperature reducing gas through the methane reforming reaction. The high-temperature reducing gas includes carbon monoxide and hydrogen. The methane reforming reactor 4 is connected to the direct reduction shaft furnace 1 and is used to introduce a portion of the high-temperature reducing gas into the direct reduction shaft furnace 1.

[0041] The direct reduction shaft furnace 1 is a place where iron ore is reduced to direct reduced iron (DRI, also known as sponge iron) and the furnace top gas is generated.

[0042] The methanol synthesis unit is a place where methanol synthesis feed gas is converted into methanol-rich product gas through a methanol synthesis reaction.

[0043] The methanol separation unit is used to purify the methanol-rich product gas to obtain methanol product and low-temperature reducing gas; the methanol separation unit is provided with a methanol outlet, which is connected to the direct reduction vertical furnace 1;

[0044] The methanol synthesis feed gas includes another portion of the high-temperature reducing gas and the low-temperature reducing gas.

[0045] An exemplary method for producing methanol from iron using methane reforming gas using the system provided in this application includes the following steps:

[0046] S1. Methane-rich gas is mixed with top gas in the feed gas supply unit to obtain methane reforming feed gas, whose main components are methane, carbon dioxide, and water vapor. To ensure complete reaction of the methane gas, the ratio of methane to carbon dioxide in the methane reforming feed gas is, for example, close to or slightly less than 1:1.

[0047] S2. The methane reforming feed gas enters the methane reforming reactor 4, where it undergoes a methane reforming reaction to become a high-temperature reducing gas, primarily composed of carbon monoxide and hydrogen. The high-temperature reducing gas also contains small amounts of carbon dioxide and methane. The temperature of the high-temperature reducing gas is, for example, 800–1300°C. The methane reforming reaction mainly includes methane steam reforming and methane dry gas reforming. The steam and carbon dioxide required for the reaction originate from the top gas of the furnace. The main chemical equations involved are:

[0048] I. CH4 + H2O → CO + 3H2;

[0049] II. CH4 + CO2 → 2CO + 2H2.

[0050] S3. A portion of the high-temperature reducing gas from the outlet of the methane reforming reactor 4 enters the direct reduction shaft furnace 1 and reacts with the iron ore from the top of the furnace to reduce the iron ore to DRI. The DRI is discharged from the bottom of the furnace. The top gas obtained from the top of the direct reduction shaft furnace 1, which mainly consists of carbon dioxide and water vapor, enters the feed gas supply unit as the source of feed gas for methane reforming and is reused.

[0051] S4. The other part of the high-temperature reducing gas is used as the feed gas for methanol synthesis. It enters the methanol synthesis unit, where carbon monoxide, carbon dioxide, and hydrogen are converted into methanol through a methanol synthesis reaction, yielding a methanol-rich product gas. The main chemical equations involved in the methane synthesis reaction are:

[0052] III. CO + 2H₂ → CH₃OH;

[0053] IV. CO2 + 3H2 → CH3OH + H2O.

[0054] S5. The methanol-rich product gas enters the methanol separation unit, where it is purified to separate methanol as the product. The separated methanol has a purity of, for example, >99%. Depending on the shaft furnace reaction efficiency and product price, a portion of the methanol can be recycled back to the direct reduction shaft furnace 1. Iron ore catalyzes the decomposition of methanol into carbon monoxide and hydrogen, which are then used as reducing gas in the shaft furnace for ironmaking, thereby improving the furnace's production efficiency and maximizing profits. Simultaneously, the methanol separation unit separates unreacted carbon monoxide, carbon dioxide, and hydrogen, which are used as low-temperature reducing gas and mixed with high-temperature reducing gas as raw material for methanol synthesis, for reuse. Additionally, the methanol separation unit can also separate impurity gases such as nitrogen. The separation of carbon monoxide, carbon dioxide, and hydrogen from impurity gases such as nitrogen employs known methods, such as adsorption, utilizing the differences in adsorption capacity of adsorbents for different gases; or distillation, utilizing the differences in boiling points between different gases through distillation, etc.

[0055] Through the above methods, the carbon dioxide produced by ironmaking will not be emitted to the outside, but will be converted back into usable carbon monoxide as raw material for methane reforming, thereby reducing carbon emissions. At the same time, the carbon elements input by methane will eventually be converted into methanol, achieving carbon fixation while generating additional economic benefits. In addition, depending on product price fluctuations, some of the by-product methanol can be used as a means to improve the quality and efficiency of the reducing gas in the direct reduction shaft furnace 1, thereby maximizing economic benefits.

[0056] Please continue to refer to this. Figure 1 In some embodiments, the feed gas supply unit includes a first buffer tank 3, which is the place where the methane-rich gas is mixed with the top gas to form the methane reforming feed gas. In step S1 above, the methane-rich gas and the top gas enter the first buffer tank 3 and mix in the first buffer tank 3 to form methane reforming feed gas whose main components are methane, carbon dioxide and water vapor.

[0057] Please continue to refer to this. Figure 1 Furthermore, in some embodiments, the bottom of the first buffer tank 3 is provided with a condensate outlet for discharging a small amount of condensate from the top gas. When methane-rich gas mixes with the top gas, some of the water vapor in the top gas may condense into water; therefore, a condensate outlet is provided at the bottom of the first buffer tank 3 to discharge the condensate.

[0058] In some embodiments, the methane reforming reactor 4 is loaded with a first catalyst, which is the catalyst required for the methane reforming reaction. The methane reforming reaction is typically carried out in the presence of a catalyst. Exemplarily, the methane reforming reactor 4 includes, but is not limited to, fixed-bed reactors, fluidized-bed reactors, and microchannel reactors, etc., and the first catalyst is selected from one or more combinations of nickel, aluminum, titanium, cobalt, vanadium, chromium, manganese, iron, copper, zinc, platinum, palladium, ruthenium, rhodium, iridium, and their corresponding oxides and derivatives, but is not limited thereto.

[0059] Furthermore, in some embodiments, the methane reforming reactor 4 is provided with a catalyst bed loaded with the first catalyst. The methane reforming feed gas enters the methane reforming reactor 4, passes through the catalyst bed, and undergoes a methane reforming reaction under the action of the first catalyst.

[0060] Please continue to refer to this. Figure 1 In some embodiments, the methanol synthesis unit includes a pressurizing device 8 and a methanol synthesis reactor 9. The pressurizing device 8 is used to pressurize, cool, and dehydrate the methanol synthesis feed gas, and the methanol synthesis reactor 9 is the site where the methanol synthesis feed gas is converted into the methanol-rich product gas through a methanol synthesis reaction. The pressurizing device 8 is, for example, a compressor, and the pressurized methanol synthesis feed gas has a pressure of, for example, 1.5–5 MPaG; the methane synthesis reactor is, for example, a fixed-bed reactor, a fluidized-bed reactor, or a microchannel reactor.

[0061] Furthermore, in some embodiments, the methanol synthesis reactor 9 is loaded with a second catalyst, which is the catalyst required for the methanol synthesis reaction. The methanol synthesis reaction described above is typically carried out in the presence of a catalyst. Exemplarily, the second catalyst is selected from one or more combinations of manganese, iron, cobalt, nickel, copper, zinc, titanium, aluminum, magnesium, indium, tungsten, platinum, palladium, ruthenium, rhodium, silver, gold, and their corresponding oxides and derivatives, but is not limited thereto.

[0062] Furthermore, in some embodiments, the methanol synthesis reactor 9 is provided with a catalyst bed loaded with the second catalyst. Methane synthesis feed gas enters the methane synthesis reactor, passes through the catalyst bed, and undergoes a methane synthesis reaction under the action of the second catalyst.

[0063] Please continue to refer to this. Figure 1 In some embodiments, the methanol synthesis unit further includes a second buffer tank 7, which is a place where another portion of the high-temperature reducing gas is mixed with the low-temperature reducing gas and cooled to form the methanol synthesis feedstock gas. The other portion of the high-temperature reducing gas is first mixed with unreacted carbon monoxide, hydrogen, carbon dioxide, etc. (i.e., the low-temperature reducing gas) separated from the methanol separation unit, and then subsequent operations are performed, including pressurization, cooling and dehydration, heating, and the methanol synthesis reaction.

[0064] Please continue to refer to this. Figure 1 In some embodiments, the methanol separation unit includes a methanol purification device 10, which separates methanol from the methanol-rich product gas by liquefying methanol, and obtains the low-temperature reducing gas. The methanol-rich product gas produced from methanol synthesis enters the methanol purification device 10, where methanol is liquefied and separated as a product from the bottom of the device. A portion is returned to the direct reduction shaft furnace 1, and the other portion can be stored. Further, in some embodiments, the methanol separation unit also includes a storage tank for storing the separated methanol.

[0065] Please continue to refer to this. Figure 1 In some embodiments, the methanol purification device 10 is provided with a gas outlet, which is connected to the second buffer tank 7. Unreacted carbon monoxide, hydrogen, carbon dioxide, etc. (i.e., the low-temperature reducing gas) are separated and enter the second buffer tank 7 to mix with the high-temperature reducing gas.

[0066] Please refer to Figure 2 In some embodiments, the system further includes a power supply device 5 connected to the methane reforming reactor 4, used to generate heat by supplying electricity to provide Joule heat for the methane reforming reaction. In step S2 above, because the methane reforming reaction is a strongly endothermic reaction, it is usually carried out at high temperatures, for example, maintaining a reaction temperature of 950–1100°C. Using the power supply device 5 to generate heat, known as Joule heat, allows the Joule heating effect to be utilized to provide heat for the methane reforming reaction. Thus, the heat required for methane reforming comes from Joule heat generated by electricity, preventing additional carbon dioxide emissions caused by the use of fossil fuels.

[0067] Furthermore, in some embodiments, the power supply equipment 5 is also connected to the direct reduction shaft furnace 1 to generate heat through power supply, providing Joule heat for the reduction reaction inside the furnace. In this way, the heat required for ironmaking also comes from the Joule heat generated by electricity, which can further prevent additional carbon dioxide emissions caused by the use of fossil fuels and achieve zero carbon emissions as much as possible.

[0068] Furthermore, in some embodiments, the power supply device 5 is connected to the catalyst bed containing the first catalyst. When the catalyst bed is energized, it generates Joule heat required for the methane reforming reaction. Exemplarily, the catalyst bed containing the first catalyst includes a conductive metal support on which the first catalyst is supported. The catalyst bed in the methane reforming reactor 4 uses a conductive metal support to support the first catalyst, and the power supply device 5 is connected to the conductive metal support, generating Joule heat required for the methane reforming reaction when energized.

[0069] Please refer to Figure 3In some embodiments, the system further includes a dust removal unit 2, which is used to remove dust from the top gas discharged from the direct reduction shaft furnace 1. This unit is located between the direct reduction shaft furnace 1 and the raw material gas supply unit. The top gas first enters the dust removal unit 2 for dust removal, and then enters the first buffer tank 3 to mix with methane-rich gas from the outside. The dust removal unit 2 includes, for example, a coarse dust collector and a fine dust collector, and the dust content of the top gas after dust removal is, for example, less than 10 mg / Nm³. 3 .

[0070] Please refer to Figure 4 In some embodiments, the system further includes a cooler 6, which is connected to both the direct reduction shaft furnace 1 and the methanol synthesis unit. The cooler 6 serves as a heat exchanger between the direct reduced iron produced by the direct reduction shaft furnace 1 and the methanol synthesis feedstock gas. The methanol synthesis feedstock gas formed by mixing low-temperature reducing gas and high-temperature reducing gas has a relatively low temperature, for example, 40–80°C, and needs to be heated before the methanol synthesis reaction. By setting up the cooler 6, the hot DRI exiting from the bottom of the direct reduction shaft furnace 1 exchanges heat with the methanol synthesis feedstock gas, cooling the hot DRI to cold DRI while simultaneously heating the methanol synthesis feedstock gas to raise its temperature before the methanol synthesis reaction. For example, the methanol synthesis feedstock gas is heated to, for example, 250–500°C, and the methanol synthesis reaction temperature is, for example, 200–500°C. In this way, the heat required for methanol synthesis is provided by the hot DRI, eliminating the need for additional heating.

[0071] Please continue to refer to this. Figure 4 Furthermore, in some embodiments, the cooler 6 is connected to the direct reduction shaft furnace 1, the pressurizing equipment, and the methanol synthesis reactor, respectively. The cooler 6 serves as a heat exchange station for the direct reduced iron produced by the direct reduction shaft furnace 1 and the methanol synthesis feed gas, which has been pressurized, cooled, and dehydrated by the pressurizing equipment. After being pressurized, cooled, and dehydrated, the methanol synthesis feed gas enters the cooler 6 for heat exchange with the direct reduced iron before entering the methanol synthesis reactor for the methanol synthesis reaction.

[0072] The above embodiments are merely illustrative of the principles and effects of this application and are not intended to limit this application. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this application. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this application should still be covered by the claims of this application.

Claims

1. A system for co-producing methanol from iron ore using methane reforming gas, characterized in that, It includes a feed gas supply unit, a methane reforming reactor, a direct reduction shaft furnace, a methanol synthesis unit, and a methanol separation unit; The feed gas supply unit is used to supply methane reforming feed gas to the methane reforming reactor. The methane reforming feed gas includes methane-rich gas and top gas from the direct reduction shaft furnace, which includes carbon dioxide and water vapor. The methane reforming reactor is the place where the methane reforming feed gas is converted into high-temperature reducing gas through the methane reforming reaction. The high-temperature reducing gas includes carbon monoxide and hydrogen. The methane reforming reactor is connected to the direct reduction shaft furnace and is used to introduce a portion of the high-temperature reducing gas into the direct reduction shaft furnace. The direct reduction shaft furnace is a place where iron ore is reduced to direct reduced iron and the furnace top gas is generated. The methanol synthesis unit is a place where methanol synthesis feed gas is converted into methanol-rich product gas through a methanol synthesis reaction. The methanol separation unit is used to purify the methanol-rich product gas to obtain methanol product and low-temperature reducing gas; the methanol separation unit is provided with a methanol outlet, which is connected to the direct reduction vertical furnace; The methanol synthesis feed gas includes another portion of the high-temperature reducing gas and the low-temperature reducing gas.

2. The system for co-producing methanol from iron ore using methane reforming gas according to claim 1, characterized in that: The raw material gas supply unit includes a first buffer tank, which is the place where the methane-rich gas is mixed with the top gas.

3. The system for co-producing methanol from iron ore using methane reforming gas according to claim 2, characterized in that: The first buffer tank is provided with a condensate outlet at the bottom, which is used to discharge condensate.

4. The system for co-producing methanol from iron ore using methane reforming gas according to claim 1, characterized in that: The methane reforming reactor is loaded with a first catalyst, which is the catalyst required for the methane reforming reaction.

5. The system for co-producing methanol from iron ore using methane reforming gas according to claim 1, characterized in that: The methanol synthesis unit includes a pressurizing device and a methanol synthesis reactor. The pressurizing device is used to pressurize, cool, and dehydrate the methanol synthesis feed gas. The methanol synthesis reactor is the place where the methanol synthesis feed gas is converted into the methanol-rich product gas through a methanol synthesis reaction.

6. The system for co-producing methanol from iron ore using methane reforming gas according to claim 5, characterized in that: The methanol synthesis reactor is loaded with a second catalyst, which is the catalyst required for the methanol synthesis reaction. And / or, the methanol synthesis unit further includes a second buffer tank, which is a place where another part of the high-temperature reducing gas is mixed with the low-temperature reducing gas and cooled to form the methanol synthesis feedstock gas.

7. The system for co-producing methanol from iron ore using methane reforming gas according to claim 1, characterized in that: The methanol separation unit includes a methanol purification device, which is used to separate methanol from the methanol-rich product gas by liquefying methanol and obtain the low-temperature reducing gas.

8. The system for co-producing methanol from iron ore using methane reforming gas according to claim 7, characterized in that: The methanol purification device is equipped with a gas outlet, which is connected to the second buffer tank.

9. The system for co-producing methanol from iron ore using methane reforming gas according to any one of claims 1 to 8, characterized in that: The system also includes a power supply device connected to the methane reforming reactor, which is used to generate heat by supplying power to provide Joule heat for the methane reforming reaction. And / or, the system further includes a dust removal unit for removing dust from the top gas discharged from the direct reduction shaft furnace, and is located between the direct reduction shaft furnace and the raw material gas supply unit; And / or, the system further includes a cooler connected to the direct reduction shaft furnace and the methanol synthesis unit, respectively, and the cooler is a place for heat exchange between the direct reduced iron produced by the direct reduction shaft furnace and the methanol synthesis feed gas.

10. The system for co-producing methanol from iron ore using methane reforming gas according to claim 9, characterized in that: The cooler is connected to the direct reduction shaft furnace, the pressurizing equipment, and the methanol synthesis reactor, respectively. The cooler is a place for heat exchange between the direct reduced iron produced by the direct reduction shaft furnace and the methanol synthesis feed gas after being pressurized, cooled, and dehydrated by the pressurizing equipment.

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