Carbon reduction method for direct reduction device

Abstract

The invention belongs to the technical field of metallurgy, and relates to a carbon reduction method for a direct reduction device, which comprises the following steps: step 1, feeding a carbon-containing raw material and an oxidant into a conversion unit for oxidation reaction to obtain crude synthesis gas; 2, feeding the crude synthesis gas into a direct reduction unit for ironmaking, and respectively feeding furnace top gas discharged by the direct reduction unit into a conversion unit and a tail gas discharge unit after dust removal by a dust removal unit; 3, a part of the furnace top gas and a carbon-containing raw material are subjected to a reforming reaction in a conversion unit to obtain synthesis gas, and the synthesis gas is fed into a direct reduction unit for ironmaking; and the other part of furnace top gas is discharged after being treated by the tail gas discharge unit. According to the method, a carbon dioxide closed-loop conversion system is constructed, efficient carbon reduction is achieved through a coupling mechanism of non-catalytic partial oxidation and autothermal reforming, and compared with a traditional hydrogen-based shaft furnace ironmaking method, the carbon reduction method has the advantage that the carbon dioxide emission is reduced by at least 25%.

Description

Technical Field

[0001] The present invention belongs to the technical field of metallurgy and relates to a carbon reduction method for a direct reduction device. Background Art

[0002] The non-catalytic partial oxidation technology does not require a catalyst, and the flame and high temperature in the furnace can achieve the reforming conversion of carbon-containing raw materials and carbon dioxide. Therefore, it has the potential to further reduce carbon. Taking the non-catalytic conversion furnace of gaseous hydrocarbons as an example, the reactions that occur can be roughly summarized as the following reaction equations. The non-catalytic partial oxidation furnace reaction is mainly based on reaction equation (1), CO 2 The dry reforming conversion reaction is mainly based on reaction equation (3):

[0003] 2CH 4 +O 2 →2CO + 4H 2 ΔrHm θ =-73.716 kJ mol -1 (1)

[0004] CH 4 +2O 2 →CO 2 +2H 2 OΔrHm θ =-802.804 kJ mol -1 (2)

[0005] CH 4 +CO 2 →2CO + 2H 2 ΔrHm θ =+245.926 kJ mol -1 (3)

[0006] CH 4 +O 2 →CO + H 2 OΔrHm θ =-520.02 kJ mol -1 (4)

[0007] CH 4 →C + H 2 ΔrHm θ =+73.843 kJ mol -1 (5)

[0008] Non-catalytic partial oxidation is an autothermal reaction, and the heat released by the reaction can be directly utilized by the reactions in the direct reduction device. If the carbon dioxide generated by the direct reduction device and the carbon-containing raw materials are reformed by the heat generated by the autothermal conversion furnace, the conversion of carbon dioxide can be achieved while providing more heat for the direct reduction device, eliminating the need to use a heating furnace.

[0009] In addition, although a catalyst is not required in the non-catalytic partial oxidation furnace, a catalyst can also be selected and set according to actual conditions to adjust the reforming reaction in the furnace. The carbon monoxide generated by carbon dioxide reforming can be used for the reduction reaction of the direct reduction device, reducing the consumption of carbon-containing raw materials and further reducing carbon emissions. Summary of the Invention

[0010] In view of this, the purpose of the present invention is to provide a carbon reduction method for a direct reduction device. This carbon reduction method uses a hybrid reforming device to convert the carbon dioxide generated by the direct reduction device into carbon monoxide and then recycle it to the direct reduction device, reducing the consumption of carbon-containing raw materials while providing the heat required for reducing iron ore, thereby achieving the purpose of further carbon reduction.

[0011] To achieve the above purpose, the present invention provides the following technical solutions:

[0012] A carbon reduction method for a direct reduction device, comprising the following steps:

[0013] Step 1: Feed a carbon-containing raw material and an oxidant into a conversion unit for an oxidation reaction to obtain raw syngas;

[0014] Step 2: Feed the raw syngas into a direct reduction unit for ironmaking, and after the top gas discharged from the direct reduction unit is dust-removed by a dust removal unit, it is respectively fed into the conversion unit and the tail gas emission unit;

[0015] Step 3: A part of the top gas undergoes a reforming reaction with the carbon-containing raw material in the conversion unit to obtain syngas, and the syngas is fed into the direct reduction unit for ironmaking; another part of the top gas is discharged after being treated by the tail gas emission unit.

[0016] In the conversion unit, the partial oxidation reaction of the carbon-containing raw material and the reforming reaction of the carbon-containing raw material with carbon dioxide mainly occur, generating the raw syngas and syngas required for iron ore reduction, and providing the heat required for reduction for iron ore reduction.

[0017] Further, in Step 2, after the top gas is dust-removed by the dust removal unit, it is first fed into a waste heat recovery unit for waste heat recovery and moisture separation, and then respectively fed into the conversion unit and the tail gas emission unit;

[0018] In Step 1, before feeding the carbon-containing raw material and the oxidant into the conversion unit, the carbon-containing raw material and the oxidant are preheated by the waste heat recovery unit to utilize the waste heat of the top gas.

[0019] Further, the carbon-containing raw material is one or more of coal, biomass, liquid hydrocarbons, heavy oil, residue oil, natural gas, coalbed methane, shale gas, coke oven gas, coal gasification gas, and chemical industrial tail gas.

[0020] Further, the oxidant is one or more of air, oxygen, water vapor, and carbon dioxide.

[0021] Further, the conversion unit includes at least one conversion device. When there are multiple conversion devices, their arrangement forms are in series or in parallel;

[0022] When the arrangement form is in parallel, top gas is introduced into at least one of the conversion devices. The conversion device can specifically adopt a reforming furnace, and a catalyst can be set or not set in the reforming furnace according to needs.

[0023] Further, the treatment method of the top gas by the tail gas emission unit is decarbonization or hydrogen extraction, or a combination of both, or directly sending it out;

[0024] The decarbonized gas and / or hydrogen obtained after the tail gas emission unit treats the top gas are mixed with the raw syngas and the syngas to form a reducing gas, which is sent to the direct reduction unit for ironmaking.

[0025] Further, the heat required for the carbon dioxide reforming of the carbonaceous raw material in the conversion unit and the carbon dioxide in the top gas is provided by a combination of one or more heating methods, including the combustion reaction heating of the carbonaceous raw material and oxygen in the conversion unit, plasma heating, and industrial furnace heating.

[0026] Further, the dust removal unit is a high-temperature dust removal unit, and single-stage dust removal or multi-stage dust removal can be correspondingly adopted according to needs.

[0027] The beneficial effects of the present invention are as follows:

[0028] The core innovation of the present invention lies in constructing a carbon dioxide closed-loop conversion system, and realizing efficient carbon reduction through the coupling mechanism of non-catalytic partial oxidation and autothermal reforming. Specifically, in the conversion unit, the partial oxidation of the carbonaceous raw material (such as reaction formula 1) and the dry reforming of carbon dioxide (such as reaction formula 3) are carried out simultaneously. The exothermic reaction of the former (ΔrHmθ = -73.716 kJ / mol) directly drives the endothermic reaction of the latter (ΔrHmθ = +245.926 kJ / mol) to form a self-heating system. The carbon dioxide generated by the direct reduction device returns to the conversion unit to participate in the reforming after dust removal, and the syngas rich in CO and H 2 is recycled for ironmaking, which not only replaces the consumption of some carbonaceous raw materials (such as natural gas), but also avoids the problem of direct emission of CO 2 in the traditional process. This closed-loop design significantly reduces the carbon emissions and saves the energy input of the external heating furnace at the same time.

[0029] The present invention breaks through the limitations of traditional catalytic reforming and proposes a flexible process framework of "mainly non-catalytic, catalytic optional". The conversion equipment can complete the main reaction without a catalyst, greatly reducing sulfur sensitivity and equipment maintenance costs, and is especially suitable for the gas environment with high impurity content in the steel industry. At the same time, for different raw material characteristics (such as coal, biomass, coke oven gas, etc.) or tail gas components, catalysts can be selected to be added in some conversion equipment to optimize the reaction path, for example, to inhibit side reactions of carbon deposition (such as Reaction 5). In addition, the waste heat of the top gas of the furnace is used to preheat the raw materials and oxidants through the waste heat recovery unit, and hydrogen or decarbonized gas is extracted and recycled by combining with the tail gas treatment unit, further improving the energy efficiency and raw material adaptability of the system, and making the process compatible with various oxidant combinations such as air, oxygen, and steam.

[0030] The present invention realizes cost reduction and efficiency improvement at the industrial level through the collaborative optimization of multiple units. The high-temperature dust removal unit can ensure that the top gas of the furnace directly enters the conversion unit at above 600 °C, avoiding heat loss; the parallel / series layout of the conversion equipment supports flexible adjustment of the production line. For example, only some equipment needs to be fed with the top gas of the furnace at low load. The linkage design of the tail gas treatment unit and the syngas (such as the mixed recycling of decarbonized gas) can further reduce the carbon emission intensity. The measured data shows that compared with the traditional hydrogen-based shaft furnace ironmaking method, the carbon dioxide emissions are at least reduced by 25% by using the carbon reduction method of the present invention.

[0031] Other advantages, objectives and features of the present invention will be described to some extent in the subsequent specification, and to some extent, will be obvious to those skilled in the art based on the study of the following text, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the following specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be described in detail preferably with reference to the accompanying drawings, where:

[0033] Figure 1 It is a schematic diagram of a carbon reduction method for a direct reduction device in the present invention;

[0034] Figure 2 It is a schematic diagram of a carbon reduction method for a direct reduction device in Embodiment 1 of the present invention;

[0035] Figure 3 It is a schematic diagram of a carbon reduction method for a direct reduction device in Embodiment 2 of the present invention;

[0036] Figure 4 It is a schematic diagram of a carbon reduction method for a direct reduction device in Embodiment 3 of the present invention;

[0037] Figure 5Schematic diagram of a carbon reduction method for a direct reduction device in Embodiment 4 of the present invention.

[0038] Reference numerals: 1 - conversion unit, 2 - direct reduction unit, 3 - dust removal unit, 4 - waste heat recovery unit, 5 - tail gas emission unit, 6 - No. 1 reforming furnace, 7 - No. 2 reforming furnace, 8 - decarbonization unit, 9 - hydrogen extraction unit;

[0039] F1 - carbonaceous raw material, F2 - preheated carbonaceous raw material, F3 - carbonaceous raw material in No. 1 reforming furnace, F4 - carbonaceous raw material in No. 2 reforming furnace, O1 - oxidant, O2 - preheated oxidant, O3 - oxidant in No. 1 reforming furnace, O4 - oxidant in No. 2 reforming furnace, M - iron ore, D - sponge iron, T1 - top gas for reforming, T2 - un-reformed top gas, S1 - crude syngas at the outlet of No. 1 reforming furnace, S2 - crude syngas at the outlet of No. 2 reforming furnace, RG - reducing gas, DG - desorbed gas, DC - decarbonized gas, CH - recycled hydrogen, OG - hydrogen extraction tail gas. Specific implementation manners

[0040] The following uses specific specific examples to illustrate the implementation manners 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 implementation manners. 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. It should be noted that the drawings provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0041] Among them, the drawings are only for illustrative purposes, showing only schematic diagrams, not physical diagrams, and should not be construed as limiting the present invention; in order to better illustrate the embodiments of the present invention, some components in the drawings will be omitted, enlarged or reduced, and do not represent the dimensions of actual products; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0042] In the drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "rear", etc. indicating the orientation or positional relationship, they are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0043] Please refer to Figure 1 , a carbon reduction method for a direct reduction device, and a corresponding carbon reduction system is provided. The system includes a conversion unit 1, a direct reduction unit 2, a dust removal unit 3, and a tail gas emission unit 5. The conversion unit 1 has an inlet for accessing a carbon-containing raw material, an oxidant, and top gas, and an outlet for discharging raw syngas and syngas. The outlet of the conversion unit 1 is connected to the direct reduction unit 2 to send the raw syngas and syngas into the direct reduction unit 2;

[0044] The inlet of the dust removal unit 3 is connected to the direct reduction unit 2, and the outlet is respectively connected to the conversion unit 1 and the tail gas emission unit 5 to send the top gas discharged from the direct reduction unit 2 to the conversion unit 1 and the tail gas emission unit 5 for reforming and emission after dust removal.

[0045] This carbon reduction method includes the following steps:

[0046] Step 1: Send a carbon-containing raw material and an oxidant into the conversion unit for an oxidation reaction to obtain raw syngas;

[0047] Step 2: Send the raw syngas into the direct reduction unit for ironmaking, and send the top gas discharged from the direct reduction unit to the conversion unit and the tail gas emission unit after dust removal by the dust removal unit;

[0048] Step 3: A part of the top gas undergoes a reforming reaction with the carbon-containing raw material in the conversion unit to obtain syngas, and the syngas is sent into the direct reduction unit for ironmaking; another part of the top gas is discharged after being treated by the tail gas emission unit.

[0049] In the conversion unit, partial oxidation reactions of carbon-containing raw materials and reforming reactions of carbon-containing raw materials with carbon dioxide mainly occur, generating the raw syngas and syngas required for iron ore reduction, and providing the heat required for reduction for iron ore reduction.

[0050] Further, in Step 2, after the top gas is dust-removed by the dust removal unit 3, it is first sent to the waste heat recovery unit 4 for waste heat recovery and moisture separation, and then sent to the conversion unit and the tail gas emission unit respectively;

[0051] In Step 1, before sending the carbon-containing raw material and the oxidant into the conversion unit, the carbon-containing raw material and the oxidant are preheated by the waste heat recovery unit to utilize the waste heat of the top gas.

[0052] Further, the carbon-containing raw material is one or more of coal, biomass, liquid hydrocarbons, heavy oil, residue oil, natural gas, coalbed methane, shale gas, coke oven gas, coal gasification gas, and chemical tail gas.

[0053] Further, the oxidant is one or more of air, oxygen, water vapor, and carbon dioxide.

[0054] Further, the conversion unit includes at least one conversion device, and when there are multiple conversion devices, their arrangement form is in series or parallel;

[0055] When the arrangement form is parallel, top gas is introduced into at least one of the conversion devices. The conversion device can specifically be a reformer. The direct reduction unit is a hydrogen-based shaft furnace, and a catalyst can be provided or not provided in the reformer as needed.

[0056] Further, the treatment method of the top gas by the tail gas emission unit is decarbonization or hydrogen extraction, or a combination of both, or direct external delivery;

[0057] The decarbonized gas and / or hydrogen obtained after the tail gas emission unit treats the top gas are mixed with the raw syngas and the syngas to form a reducing gas, which is sent to the direct reduction unit for ironmaking.

[0058] Further, the heat required for the carbon dioxide reforming of the carbonaceous raw material in the conversion unit and the carbon dioxide in the top gas is provided by a combination of one or more heating methods, including the combustion reaction heating of the carbonaceous raw material and oxygen in the conversion unit, plasma heating, and industrial furnace heating.

[0059] Further, the dust removal unit is a high-temperature dust removal unit, and single-stage dust removal or multi-stage dust removal can be correspondingly adopted as needed.

[0060] To further describe this carbon reduction method, the following provides further detailed description in conjunction with the accompanying drawings.

[0061] Taking natural gas with a methane content of 95% as the carbonaceous raw material F1 and oxygen with a purity of 99% as the oxidant O1 as an example, without considering the carbon dioxide generated by external input heat sources such as electricity and steam, only measuring the amount of carbon dioxide emitted by this system to the outside, the method disclosed in the embodiment is compared with the ironmaking method of a direct reduction device without carbon dioxide conversion (comparative example).

[0062] Example 1

[0063] As Figure 2 shown, in this embodiment, the conversion unit 1 is the No. 1 reformer 6, and the tail gas emission unit 5 is set as the decarbonization unit 8; natural gas with a methane content of 95% as the carbonaceous raw material F1 and oxygen with a purity of 99% as the oxidant O1 are heated to 300 °C by the waste heat recovery unit 4 to obtain the preheated carbonaceous raw material F2 and the preheated oxidant O2;

[0064] The preheated oxygen and carbonaceous raw materials are fed into the No. 1 reforming furnace 6 at a ratio of 0.9 / 1. In addition, a part of the top gas T1 for reforming is added. The carbon dioxide content in both the top gas T1 for reforming and the un-reformed top gas T2 is about 15%. In the No. 1 reforming furnace 6, the partial oxidation reaction of methane, the steam reforming reaction of methane, and the carbon dioxide reforming reaction of methane occur simultaneously. At the outlet of the No. 1 reforming furnace 6, a crude syngas S1 at the outlet of the No. 1 reforming furnace is formed. The parameters of the crude syngas S1 at the outlet of the No. 1 reforming furnace are a temperature of 1000 °C, an effective gas (CO + H 2 ) content of about 85%, and a carbon dioxide content of about 2.5% after reforming; The un-reformed top gas T2 that does not participate in the reforming reaction enters the decarbonization unit 8 to increase the effective gas content to about 90%, and a refined decarbonized gas DC is obtained;

[0065] The crude syngas S1 at the outlet of the No. 1 reforming furnace is mixed with the refined decarbonized gas DC and then used as the reducing gas RG to be fed into the direct reduction unit II to react with the iron ore M, obtaining sponge iron D. The temperature of the reducing gas is about 980 °C, and the effective gas content is about 86%; The carbon entering the system is discharged to the outside through the desorbed gas DG of the decarbonization unit 8, and the carbon dioxide output to the outside is about 0.65 t.CO 2 / t.DRI.

[0066] Example 2

[0067] As Figure 3 shown, in this embodiment, the reforming unit 1 is the parallel No. 1 reforming furnace 6 and No. 2 reforming furnace 7, and the tail gas emission unit 5 is set as the decarbonization unit 8; Natural gas with a methane content of 95% is used as the carbonaceous raw material F1, and oxygen with a purity of 99% is used as the oxidant O1. After being heated to 300 °C through the waste heat recovery unit 4, the preheated carbonaceous raw material F2 and the preheated oxidant O2 are obtained;

[0068] One part of the preheated oxygen is used as the oxidant O3 for the No. 1 reforming furnace, and natural gas is used as the carbonaceous raw material F3 for the No. 1 reforming furnace. They are fed into the No. 1 reforming furnace 6 at a ratio of 0.8 / 1, mainly undergoing the partial oxidation reaction of methane. At the outlet of the No. 1 reforming furnace 6, a crude syngas S1 at the outlet of the No. 1 reforming furnace is formed. The parameters of the crude syngas S1 at the outlet of the No. 1 reforming furnace are a temperature of 1200 °C and an effective gas (CO + H 2 ) content of about 85%;

[0069] Another part of the preheated oxygen enters the 2# reformer 7 as the reformer oxidant O4, and the carbonaceous feedstock enters the 2# reformer 7 as the carbonaceous feedstock F4 together with the top gas T1 for reforming. The methane carbon dioxide reforming reaction and the methane steam reforming reaction mainly occur, generating the raw syngas S2 at the outlet of the 2# reformer. The ratio of oxygen / carbonaceous feedstock / top gas is 5.48 / 9.31 / 1. The carbon dioxide content in the top gas is about 20%. The outlet temperature of the 2# reformer 7 is about 950 °C, the effective gas content is about 90%, and the carbon dioxide content after reforming is only about 2%.

[0070] The un-reformed top gas T2 that did not participate in the reforming reaction enters the decarbonization unit 8 to increase the effective gas content to about 90%. The raw syngas S1 at the outlet of the 1# reformer, the raw syngas S2 at the outlet of the 2# reformer, and the upgraded decarbonized gas DC are mixed and used as the reducing gas RG to enter the direct reduction unit 2 to react with the iron ore M. The temperature of the reducing gas is about 960 °C, and the effective gas content is about 88%. The carbon entering the system is discharged to the outside through the desorbed gas DG of the decarbonization unit 8, and the carbon dioxide output to the outside is about 0.62 t.CO 2 / t.DRI.

[0071] Example 3

[0072] As Figure 4 shown, in this example, the reforming unit 1 is the series-connected 1# reformer 6 and 2# reformer 7, and the tail gas emission unit 5 is set as the decarbonization unit 8. Natural gas with a methane content of 95% is used as the carbonaceous feedstock F1, and oxygen with a purity of 99% is used as the oxidant O1. After being heated to 300 °C by the waste heat recovery unit 4, the preheated carbonaceous feedstock F2 and the preheated oxidant O2 are obtained.

[0073] One part of the preheated oxygen is sent into the 1# reformer 6 as the reformer oxidant O3 and natural gas is sent into the 1# reformer 6 as the carbonaceous feedstock F3 at a ratio of 0.8 / 1. The methane partial oxidation reaction mainly occurs, and the raw syngas S1 at the outlet of the 1# reformer is formed. The parameters of the raw syngas S1 at the outlet of the 1# reformer are a temperature of 1400 °C and an effective gas (CO + H 2 ) content of about 80%.

[0074] Another part of the preheated oxygen enters the 2# reformer 7 as the reformer oxidant O4, and the carbonaceous feedstock enters the 2# reformer 7 as the carbonaceous feedstock F4 together with the top gas T1 for reforming. The methane carbon dioxide reforming reaction and the methane steam reforming reaction mainly occur, generating the raw syngas S2 at the outlet of the 2# reformer. The ratio of carbonaceous feedstock / top gas / raw syngas is 9.38 / 1 / 5.84. The carbon dioxide content in the top gas is about 15%. The temperature of the raw syngas (S2) at the outlet of the 2# reformer is about 1000 °C, the effective gas content is about 88%, and the carbon dioxide content after reforming is about 2.5%.

[0075] The un-reformed top gas T2 that has not participated in the reforming reaction enters the decarbonization unit 8. The decarbonized gas DC of the decarbonization unit is mixed with the raw syngas S2 at the outlet of the 2# reforming furnace and jointly serves as the reducing gas RG for the direct reduction unit. The carbon entering the system is discharged to the outside through the desorbed gas of the decarbonization unit, and the carbon dioxide output to the outside is about 0.64 t.CO 2 / t.DRI.

[0076] Example 4

[0077] As Figure 5 shown, in the example, the reforming unit 1 is the 1# reforming furnace 6, the tail gas emission unit 5 is set as the hydrogen extraction unit 9, and the carbon dioxide content in the top gas is about 15%; natural gas with a methane content of 95% is used as the carbon-containing raw material F1 and oxygen with a purity of 99% is used as the oxidant O1. After being heated to 300 °C by the waste heat recovery unit 4, the preheated carbon-containing raw material F2 and the preheated oxidant O2 are obtained;

[0078] Oxygen and natural gas enter the 1# reforming furnace 6 at a ratio of 0.9 / 1, and a part of the top gas T1 for reforming is additionally added. In the reforming furnace, the partial oxidation reaction of methane, the steam reforming reaction of methane, and the carbon dioxide reforming reaction of methane occur simultaneously. At the outlet of the 1# reforming furnace 6, the raw syngas S1 at the outlet of the 1# reforming furnace is formed. The parameters of the raw syngas S1 at the outlet of the 1# reforming furnace are a temperature of 1000 °C, and the content of effective gas (CO + H 2 ) is about 85%, and the carbon dioxide content after reforming is about 2.5%;

[0079] The un-reformed top gas T2 that has not participated in the reforming reaction enters the hydrogen extraction unit 9 to increase the effective gas content to about 90%; the raw syngas S1 at the outlet of the reforming furnace is mixed with the hydrogen CH obtained by hydrogen extraction and jointly serves as the reducing gas RG to enter the direct reduction unit 2 to react with iron ore. The temperature of the reducing gas is about 980 °C, and the effective gas content is about 88%; the carbon entering the system is discharged to the outside through the hydrogen extraction tail gas OG of the hydrogen extraction unit, and the carbon dioxide output to the outside is about 0.66 t.CO 2 / t.DRI.

[0080] Comparative example

[0081] The difference between the comparative example and Example 1 is that the top gas is all treated by the dust removal unit and the waste heat recovery unit and then enters the decarbonization unit for treatment, obtaining a decarbonized gas DG with a carbon dioxide content of about 1.9% and an effective gas content of about 95%. The decarbonized gas is heated to about 900 °C by the heating furnace and then mixed with the raw syngas S1 at the outlet of the 1# reforming furnace, obtaining a reducing gas RG with an effective gas content of about 88% and a temperature of about 950 °C; the carbon entering the system is discharged to the outside through the desorbed gas DG of the decarbonization unit, and the carbon dioxide output to the outside by the desorbed gas DG is about 0.9 t.CO 2 / t.DRI.

[0082] In summary, the highest carbon dioxide emission value in Examples 1 to 4 is 0.66 t.CO 2 / t.DRI, compared with 0.9 t.CO in the comparative example 2 / t.DRI, a 25% reduction is achieved. It can be seen that compared with the traditional hydrogen-based shaft furnace ironmaking method, by adopting the carbon reduction method of the present invention, the carbon dioxide emission is reduced by at least 25%.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the purpose and scope of the present technical solution, and they should all be covered by the scope of the claims of the present invention.

Claims

1. A carbon reduction method for a direct reduction device, characterized in that: The following steps are involved: Step 1: feeding the carbonaceous raw material and the oxidant into the conversion unit for oxidation reaction to obtain a crude synthesis gas; Step 2: sending the crude synthesis gas to a direct reduction unit for ironmaking, and sending the top gas discharged from the direct reduction unit to a conversion unit and a tail gas emission unit after dust removal by a dust removal unit; Step 3: A portion of the top gas undergoes reforming reaction with carbon-containing raw materials in the conversion unit to obtain synthesis gas, and the synthesis gas is sent to the direct reduction unit for ironmaking; the other portion of the top gas is discharged after being treated in the tail gas emission unit.

2. The carbon reduction method for a direct reduction device according to claim 1, characterized in that: In step 2, the furnace top gas is sent to the waste heat recovery unit for waste heat recovery and water separation after being dedusted by the dedusting unit, and then sent to the conversion unit and the tail gas emission unit respectively; In step 1, before the carbon-containing raw material and the oxidant are fed into the conversion unit, the carbon-containing raw material and the oxidant are preheated by a waste heat recovery unit to utilize the waste heat of the furnace top gas.

3. The carbon reduction method for a direct reduction device according to claim 1, characterized in that: The carbon-containing raw material is one or more of coal, biomass, liquid hydrocarbon, heavy oil, residual oil, natural gas, coalbed methane, shale gas, coke oven gas, coal-to-gas and chemical tail gas.

4. The carbon reduction method for a direct reduction device according to claim 1, characterized in that: The oxidant is one or more of air, oxygen, water vapor and carbon dioxide.

5. The carbon reduction method for a direct reduction device according to claim 1, characterized in that: The conversion unit comprises at least one conversion device, and when there are multiple conversion devices, they are arranged in series or in parallel; When the arrangement is in parallel, top gas is introduced into at least one of the conversion devices.

6. The carbon reduction method for a direct reduction device according to claim 1, characterized in that: The tail gas discharge unit treats the top gas by decarbonization or hydrogenation, or a combination of the two, or directly sends it out; The tail gas discharge unit processes the furnace top gas to obtain decarbonized gas and / or hydrogen, which is mixed with the crude synthesis gas and synthesis gas to form reducing gas, and is sent to the direct reduction unit for ironmaking.

7. The carbon reduction method for a direct reduction device according to claim 1, characterized in that: The heat required for reforming the carbon-containing raw materials in the conversion unit with carbon dioxide in the top gas is provided by a combination of one or more heating methods including heating by the combustion reaction of the carbon-containing raw materials and oxygen in the conversion unit, plasma heating, and industrial furnace heating.

8. The carbon reduction method for a direct reduction device according to claim 1, characterized in that: The dust removal unit is a high-temperature dust removal unit.

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