A system and method for fully hydrogenated ironmaking

Abstract

The present invention discloses a full hydrogen ironmaking system, which relates to the field of iron and steel metallurgy technology, including a molten iron vertical furnace that integrates a feeding section, a reduction section, and a melting and heating section from top to bottom, and a process gas recovery pipeline connected to the reduction section of the molten iron vertical furnace, and also includes a hydrogen injection pipeline with an inlet and an outlet respectively connected to the process gas recovery pipeline and the melting and heating section of the molten iron vertical furnace. The present invention also discloses a full hydrogen ironmaking method, which is implemented using the above system. In this way, after hydrogen is rapidly heated to hot reducing gas in the melting and heating section, it enters the reduction section to undergo a reduction reaction with iron ore. The obtained hot sponge iron enters the melting and heating section to undergo a reduction reaction with the hydrogen therein to produce molten iron. The top gas obtained in the reduction section is purified by the process gas recovery pipeline and then enters the melting and heating section through the hydrogen injection pipeline for recycling. This solves the problems of difficulty in heating hydrogen, low utilization of heat energy and reducing gas, and difficulty in controlling furnace charge, and has the advantages of high reaction efficiency and environmental friendliness.

Description

Technical Field

[0001] The present invention belongs to the technical field of iron and steel metallurgy, and in particular relates to a system and method for full-hydrogen ironmaking. Background Art

[0002] Currently, the world's most advanced direct reduction iron technology is gas-based shaft furnace direct reduction. This technology primarily uses natural gas as a feedstock. After conversion to H2- and CO-rich gas, it is directly reduced with iron ore under high-temperature solid-state conditions to produce sponge iron. Currently, the inevitable trend in the steel industry to reduce CO2 emissions is the development of hydrogen metallurgy. Using full hydrogen ironmaking can utilize the chemical energy of hydrogen, but the system's thermal energy is insufficient. Using other fuels for heating would inevitably increase carbon emissions. Using green electricity to heat hydrogen smelting, on the other hand, utilizes the chemical energy of hydrogen without increasing carbon emissions. The coupled electricity-hydrogen approach to sponge iron production is the preferred technical approach for carbon reduction.

[0003] Generally speaking, the Midrex and HYL processes, among gas-based shaft furnace processes, hold a clear advantage. With technological advancements, the requirements for reducing gases have become more diverse, with both hydrogen-rich and full hydrogen at pressures greater than 0.1 MPa being acceptable. Using full hydrogen as the reducing gas requires heating, a traditional method typically employing fuel combustion or electric heating. Fuel combustion inevitably results in significant amounts of carbon dioxide in the flue gas, increasing carbon emissions. Furthermore, heating full hydrogen can easily lead to hydrogen embrittlement, posing significant challenges to furnace materials and limiting heating temperatures. Electric heating, particularly green electricity, reduces CO2 emissions from fuel combustion, but limitations in furnace materials and heating temperatures hinder the development of full hydrogen smelting. The traditional Midrex and Energiron shaft furnaces consist of a top feeding system, a reduction system, a cooling system, and a discharge system. The reduction system occupies a relatively small portion of the shaft furnace height, while the cooling and discharge systems occupy a significant portion, resulting in energy waste and complex control. Summary of the Invention

[0004] The purpose of the present invention is to provide a system and method for all-hydrogen ironmaking to solve the problems of high carbon emissions in ironmaking, unsafe hydrogen heating, heat waste in the cooling section of the traditional vertical furnace, and complex control.

[0005] The above-mentioned purpose of the present invention can be achieved by adopting the following technical solutions:

[0006] A full hydrogen ironmaking system, comprising:

[0007] A molten iron vertical furnace having a feeding section, a reduction section, and a melting and heating section connected from top to bottom; wherein the melting and heating section has at least one hot reducing gas outlet, and at least one of the hot reducing gas outlets is connected to the reducing section;

[0008] A process gas recovery pipeline is connected to the molten iron vertical furnace, and the process gas recovery pipeline has a heat exchanger, a scrubber and a desulfurizer connected in sequence;

[0009] The hydrogen injection pipeline has a connected hydrogen injection pipe and at least one hydrogen spray gun, the hydrogen injection pipe is connected to the heat exchanger, and at least one hydrogen spray gun extends into the melting and heating section.

[0010] In a specific embodiment, the reduction section further includes a sponge iron discharge pipe, the sponge iron discharge pipe can extend into the melting and heating section, and the sponge iron discharge pipe is connected to a switch valve.

[0011] In a specific embodiment, it further includes: an electric heating mechanism is provided on the outside of the melting and heating section, and a refractory material layer is provided between the electric heating mechanism and the melting and heating section.

[0012] In a specific embodiment, the process gas recovery pipeline further includes a dehydrator, and along the gas flow direction in the process gas recovery pipeline, the dehydrator is located at the downstream end of the desulfurizer.

[0013] In a specific embodiment, the process gas recovery pipeline also includes a pressurizing mechanism, which is located at the downstream end of the dehydrator along the gas flow direction in the process gas recovery pipeline, and is connected to the inlet end of the hydrogen injection pipe.

[0014] The heat exchanger has a cold medium inlet and a cold medium outlet, and the cold medium inlet and the cold medium outlet are respectively connected to the hydrogen injection pipe.

[0015] Wherein, a plurality of flux spray guns are provided on the melting and heating section, and the plurality of flux spray guns are arranged at intervals along the circumferential direction of the melting and heating section and can extend into the slag layer in the melting and heating section.

[0016] Wherein, the flux injected into the flux spray gun is one or a combination of lime, limestone and dolomite.

[0017] There are multiple hydrogen spray guns, which are arranged at intervals along the circumferential direction of the melting and heating section and can extend into the molten iron layer in the melting and heating section.

[0018] Wherein, the reaction temperature of the melting and heating section is greater than 1500° C., and the pressure of the hydrogen injected into the melting and heating section is greater than 0.1 MPa.

[0019] A full hydrogen ironmaking method is implemented using the above-mentioned full hydrogen ironmaking system, and the method comprises the following steps:

[0020] feeding iron ore into the feed section of the molten iron shaft furnace, wherein the iron ore reacts with the hot reducing gas injected into the reducing section to produce sponge iron, water and top gas;

[0021] The top gas and the water enter the heat exchanger of the process gas recovery pipeline, are pre-cooled by the heat exchanger, are passed into the scrubber for cooling and dust removal, and are then passed into the desulfurizer for desulfurization to obtain purified top gas; the sponge iron passes through the reduction section and settles into the melting and heating section;

[0022] The purified top gas is mixed with hydrogen injected into the hydrogen injection pipe of the hydrogen injection pipeline, and after being preheated by the heat exchanger, is injected into the molten iron layer of the melting and heating section through the hydrogen lance to generate hot reducing gas that is transported to the reduction section;

[0023] The sponge iron undergoes a reduction reaction with the hydrogen injected into the melting and heating section to generate molten iron and slag.

[0024] The temperature of the top gas after pre-cooling by the heat exchanger and cooling and dust removal by the scrubber is 30°C to 50°C. The purified top gas is mixed with the hydrogen injected into the hydrogen injection pipe to form a mixed gas. The temperature of the mixed gas after preheating by the heat exchanger is 200°C to 500°C.

[0025] Among them, along the gas flow direction in the process gas recovery pipeline, a dehydrator is provided at the downstream end of the desulfurizer, and a compressor is provided at the downstream end of the dehydrator; wherein, the purified furnace top gas is dehydrated by the dehydrator to become process gas, and the process gas is pressurized by the compressor and then mixed with hydrogen at the inlet end of the hydrogen injection pipe to form a mixed gas, and the hydrogen content in the mixed gas accounts for more than 55%.

[0026] The metallization rate of the reduction section is greater than 30%, and the metallization rate of the melting and heating section is greater than 95%.

[0027] The characteristics and advantages of the full hydrogen ironmaking system and method of the present invention are:

[0028] 1. Hydrogen is rapidly heated to hot reducing gas in the melting and heating section of the molten iron vertical furnace. The hot reducing gas enters the reduction section and undergoes a reduction reaction with the iron ore. The resulting hot sponge iron directly enters the melting and heating section under the control of an on-off valve, where it undergoes a reduction reaction with hydrogen injected by a hydrogen lance under the heating of an electric heating mechanism to produce molten iron. During stable operation, the on-off valve is always open, and the discharge rate of the reduction section is controlled by the discharge of molten iron. This solves the difficulties of hydrogen heating, namely unsafe heating, slow heating rate and low temperature, heat waste in the cooling section of the traditional vertical furnace, high overall process energy consumption, and difficult charge control. It has the advantages of near-zero CO2 emissions, high reaction efficiency, and environmental friendliness.

[0029] 2. The process gas recovery pipeline connected to the molten iron vertical furnace can purify and dehydrate the furnace top gas into process gas, and then pressurize it and send it into the melting and heating section, so that the unreacted reducing gas in the reduction section can be recycled, which significantly improves the utilization rate of the reducing gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0031] Figure 1 is a schematic diagram of the full hydrogen ironmaking system of the present invention;

[0032] Figure 2 A partial schematic enlarged view of the molten iron vertical furnace of the full hydrogen ironmaking system of the present invention;

[0033] Figure 3 This is a process flow chart of the all-hydrogen ironmaking method of the present invention.

[0034] Description of Figure Numbers:

[0035] 1. Molten iron vertical furnace;

[0036] 11. Feeding section; 111. Feeding bin; 112. Iron ore inlet;

[0037] 12. Reduction section; 121. Sponge iron discharge pipe; 122. On / off valve; 123. Top gas outlet; 124. Hot reduction gas inlet;

[0038] 13. Melting and heating section; 131. Hot reducing gas outlet; 132. Electric heating mechanism; 133. Flux spray gun; 134. Slag outlet; 135. Molten iron outlet; 136. Molten iron tank;

[0039] 2. Process gas recovery pipeline; 21. Heat exchanger; 22. Scrubber; 23. Desulfurizer; 24. Dehydrator; 25. Pressurizing mechanism;

[0040] 3. Hydrogen injection pipeline; 31. Hydrogen injection pipe; 32. Hydrogen spray gun. DETAILED DESCRIPTION

[0041] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0042] Implementation Method 1

[0043] like Figures 1 to 2 As shown, the present invention provides a full hydrogen ironmaking system, which includes:

[0044] The molten iron vertical furnace 1 comprises a feeding section 11, a reduction section 12, and a melting and heating section 13, which are sequentially connected from top to bottom. The melting and heating section 13 has at least one hot reducing gas outlet 131, and the at least one hot reducing gas outlet 131 is connected to the reducing section 12.

[0045] A process gas recovery pipeline 2 connected to the molten iron vertical furnace 1, the process gas recovery pipeline 2 having a heat exchanger 21, a scrubber 22 and a desulfurizer 23 connected in sequence;

[0046] The hydrogen injection pipeline 3 is connected to the molten iron vertical furnace 1, and the hydrogen injection pipeline 3 has a connected hydrogen injection pipe 31 and at least one hydrogen spray gun 32. The hydrogen injection pipe 31 is connected to the heat exchanger 21, and the at least one hydrogen spray gun 32 extends into the melting and heating section 13 of the molten iron vertical furnace 1.

[0047] In the all-hydrogen ironmaking system of the present invention, hydrogen is rapidly heated to hot reducing gas in the melting and heating section 13 of the molten iron vertical furnace 1, which has the characteristics of fast heating rate, high heating temperature, no combustion of carbon-containing fuel, and low carbon emissions. At the same time, the process gas recovery pipeline 2 connected to the molten iron vertical furnace 1 can significantly improve the utilization rate of the reducing gas. In addition, the molten iron vertical furnace 1 of the present invention omits the cooling section of the traditional vertical furnace, effectively solving the problems of low thermal energy utilization and high overall process energy consumption in the prior art.

[0048] Specifically, such as Figure 1As shown, the feeding section 11 of the molten iron vertical furnace 1 is provided with a feeding bin 111 and an iron ore inlet 112; the reduction section 12 is located below the feeding section 11, and a furnace top gas outlet 123 is opened on its upper portion for connecting to the process gas recovery pipeline 2, and at least one hot reducing gas inlet 124 is opened on the lower portion of the reduction section 12. In this embodiment, there are multiple hot reducing gas inlets 124, and the multiple hot reducing gas inlets 124 are arranged at intervals along the circumferential direction of the reduction section 12; the melting heating section 13 is located below the reduction section 12, and a furnace top gas outlet 123 is opened on its upper portion for connecting to the process gas recovery pipeline 2. At least one hot reduction gas outlet 131 is provided. In this embodiment, there are multiple hot reduction gas outlets 131, and the multiple hot reduction gas outlets 131 are arranged at intervals along the circumferential direction of the melting and heating section 13. The multiple hot reduction gas outlets 131 of the melting and heating section 13 are connected to the multiple hot reduction gas inlets 124 of the reduction section 12 through a hot reduction gas pipeline; in the present invention, a slag outlet 134 and a molten iron outlet 135 are also provided at the lower part of the melting and heating section 13, and a molten iron tank 136 can be connected below the molten iron outlet 135. The iron ore entering from the feed section 11 of the molten iron vertical furnace 1 undergoes a reduction reaction in the reduction section 12 to obtain sponge iron. The sponge iron settles into the melting and heating section 13 and reacts to generate molten iron and slag. The molten iron is concentrated at the bottom of the melting and heating section 13 to form a molten iron layer and enters the molten iron tank 136 through the molten iron outlet 135. The slag floats above the molten iron layer to form a slag layer and is continuously discharged through the slag outlet 134. In this embodiment, the reaction temperature of the melting and heating section 13 is 1500°C to 1800°C.

[0049] The inlet end of the process gas recovery pipeline 2 is the end of the top gas outlet 123 of the reduction section 12. A heat exchanger 21, a scrubber 22, and a desulfurizer 23 are arranged in sequence along the direction of gas flow within the process gas recovery pipeline 2. The heat medium inlet and the heat medium outlet of the heat exchanger 21 are connected to the top gas outlet 123 and the inlet of the scrubber 22, respectively. The outlet of the scrubber 22 is connected to the inlet of the desulfurizer. After the top gas undergoes heat exchange in the heat exchanger 21 and is then cooled and dust-removed by the scrubber 22, the temperature of the top gas drops from 300°C to 500°C to 30°C to 50°C. The sulfur content of the top gas after desulfurization by the desulfurizer 23 is less than or equal to 10 ppmv. In this embodiment, the desulfurizer 23 can employ either dry or wet desulfurization, which is not limited by the present invention.

[0050] The inlet end of the hydrogen injection pipeline 3 is connected to an external hydrogen supply device. Along the gas flow direction in the hydrogen injection pipeline 3, a hydrogen injection pipe 31 is provided, which is connected to the cold medium inlet on the heat exchanger 21 and the cold medium outlet on the heat exchanger 21. The end of the hydrogen injection pipe 31 is connected to at least one hydrogen spray gun 32 that can extend into the melting and heating section 13. In this embodiment, there are multiple hydrogen spray guns 32, and the multiple hydrogen spray guns 32 are arranged at intervals along the circumferential direction of the melting and heating section 13 and can extend into the molten iron layer in the melting and heating section 13. In this embodiment, the pressure of the hydrogen injected into the melting and heating section 13 by the hydrogen spray gun 32 is greater than 0.1 MPa.

[0051] According to one embodiment of the present invention, the reduction section 12 has a sponge iron discharge pipe 121 , which can extend into the melting and heating section 13 . The sponge iron discharge pipe 121 is connected to a switch valve 122 .

[0052] In this embodiment, iron ore undergoes a reduction reaction in the reduction section 12 to obtain hot sponge iron. The hot sponge iron does not need to be cooled and can directly enter the molten heating section 13 through the sponge iron discharge pipe 121 under the control of the switch valve 122. The thermal energy of the hot sponge iron can be fully utilized, which promotes the rate of generating molten iron. When the system is running stably, the switch valve 122 can be kept open, and the discharge rate of the hot sponge iron in the reduction section 12 can be controlled by the discharge situation of the molten heating section 13, which is simple to control.

[0053] Specifically, such as Figure 1 As shown, the reduction section 12 has a sponge iron discharge pipe 121 located at the bottom center of the reduction section 12. The bottom center opening of the reduction section 12 is connected to the inner cavity of the sponge iron discharge pipe 121. The sponge iron discharge pipe 121 can extend into the melting and heating section 13, connecting the reduction section 12 and the melting and heating section 13. A switch valve 122 for controlling the sponge iron discharge rate is connected to the sponge iron discharge pipe 121. When the full hydrogen ironmaking system is operating stably, the switch valve 122 is always open, and the discharge rate of the hot sponge iron generated by the reduction reaction in the reduction section 12 is controlled by the discharge situation of the melting and heating section 13.

[0054] According to one embodiment of the present invention, an electric heating mechanism 132 is provided on the exterior of the melting and heating section 13, with a refractory layer (not shown) provided between the electric heating mechanism 132 and the melting and heating section 13. In this embodiment, the hydrogen injected into the melting and heating section 13 by the hydrogen lance 32 can be quickly and safely heated to form hot reducing gas, thus resolving the difficulty in heating hydrogen in the prior art.

[0055] Specifically, such as Figure 2As shown, the electric heating mechanism 132 is sleeved along the lower outer ring of the melting and heating section 13. The height of the electric heating mechanism 132 at least covers the height of the molten iron layer and the slag layer formed by the molten iron and slag generated by the reduction reaction of the sponge iron in the melting and heating section 13. In this embodiment, a refractory layer is provided between the electric heating mechanism 132 and the melting and heating section 13. This refractory layer provides insulation and increases the service life of the molten iron shaft furnace 1. In this embodiment, the electric heating mechanism 132 utilizes a medium-frequency induction heater with an output power greater than 5MW. Green electricity is preferred for heating, and alumina is used as the refractory material for the refractory layer.

[0056] According to one embodiment of the present invention, the process gas recovery pipeline 2 further comprises a dehydrator 24 , and along the gas flow direction in the process gas recovery pipeline 2 , the dehydrator 24 is located at the downstream end of the desulfurizer 23 .

[0057] In this embodiment, the dehydrator 24 can dehydrate the purified top gas, so that the dehydrated process gas helps to extend the service life of the facilities connected to the dehydrator 24 during the process gas recovery and utilization.

[0058] Specifically, such as Figure 1 As shown, the inlet of the dehydrator 24 is connected to the outlet of the desulfurizer 23. In this embodiment, the dehydrator 24 adopts one or a combination of centrifugal separation, adsorption dehydration, and freeze dehydration.

[0059] Furthermore, the process gas recovery pipeline 2 also has a pressurizing mechanism 25 , which is located at the downstream end of the dehydrator 24 along the gas flow direction in the process gas recovery pipeline 2 and is connected to the inlet end of the hydrogen injection pipe 31 .

[0060] In this embodiment, the dehydrated process gas is pressurized by the pressurizing mechanism 25 and more easily flows into the melting and heating section 13 of the molten iron vertical furnace 1 through the hydrogen injection pipe 31, thereby increasing the recycling rate of the process gas entering the melting and heating section 13.

[0061] Specifically, such as Figure 1 As shown, the inlet of the pressurizing mechanism 25 is connected to the outlet of the dehydrator 24. In this embodiment, the pressure of the dehydrated process gas after pressurization by the pressurizing mechanism 25 is 0.1-0.8 MPa.

[0062] According to one embodiment of the present invention, a plurality of flux spray guns 133 are provided on the melting and heating section 13 . The plurality of flux spray guns 133 are spaced apart along the circumferential direction of the melting and heating section 13 and can extend into the slag layer in the melting and heating section 13 .

[0063] In this embodiment, flux can be injected into the slag layer in the melting and heating section 13 through the flux spray gun 133 to lower the melting point of the sponge iron, accelerate the reduction reaction of the sponge iron, and improve the production efficiency of molten iron.

[0064] Specifically, such as Figure 2 As shown, the melting and heating section 13 is provided with a plurality of flux spray guns 133, which are arranged at intervals along the circumferential direction of the melting and heating section 13 and can extend into the slag layer in the melting and heating section 13. In this embodiment, the flux injected into the flux spray guns 133 can be one or a combination of lime, limestone, and dolomite.

[0065] Implementation Method 2

[0066] like Figure 1-3 As shown, the present invention also provides a full hydrogen ironmaking method, that is, a method for implementing electric-hydrogen coupled direct reduction ironmaking using a full hydrogen ironmaking system, the method comprising the following steps:

[0067] The iron ore is fed into the feed section 11 of the molten iron shaft furnace 1, and reacts with the hot reducing gas injected into the reduction section 12 to produce sponge iron, water and top gas;

[0068] The top gas enters the heat exchanger 21 of the process gas recovery line 2, is pre-cooled by the heat exchanger 21, passes through the scrubber 22 for cooling and dust removal, and then passes through the desulfurizer 23 for desulfurization to obtain purified top gas; the sponge iron passes through the reduction section 12 and settles into the melting and heating section 13;

[0069] The purified top gas is mixed with hydrogen from the hydrogen injection pipe 31 of the hydrogen injection pipeline 3, preheated by the heat exchanger 21, and then injected into the molten iron layer in the melting and heating section 13 through the hydrogen lance 32 to generate hot reducing gas that is transported to the reduction section 12;

[0070] The sponge iron undergoes a reduction reaction with the hydrogen injected into the melting and heating section 13 to generate molten iron and slag.

[0071] In the all-hydrogen ironmaking method of the present invention, the hydrogen injected into the melting and heating section 13 from the hydrogen injection pipe 31 of the hydrogen injection pipeline 3 can be quickly and safely heated into hot reducing gas. The hot reducing gas enters the reduction section 12 and can quickly undergo a reduction reaction with the iron ore entering from the feed section 11 to obtain hot sponge iron, water and furnace top gas. The hot sponge iron does not need to be cooled and can directly enter the melting and heating section 13. The hot sponge iron undergoes a reduction reaction with the hydrogen injected into the melting and heating section 13 to generate molten iron and slag, thereby fully utilizing the thermal energy; the furnace top gas obtained by the reaction in the reduction section 12 directly enters the process gas recovery pipeline 2 for purification, and the purified furnace top gas is mixed with the hydrogen in the hydrogen injection pipe 31 and then injected into the melting and heating section 13 by the hydrogen spray gun 32 for recycling, thereby significantly improving the utilization rate of the reducing gas in the ironmaking process.

[0072] Specifically, such as Figure 1 and Figure 3 As shown, after being processed into pellets or lump ore, iron ore is fed from the feed section 11 through the feed bin 111 and enters the reduction section 12 through the iron ore inlet 112. Hydrogen is injected into the melting and heating section 13 through the hydrogen injection pipe 31 of the hydrogen injection pipeline 3 through the hydrogen lance 32. The hydrogen is then rapidly heated to a hot reducing gas having a temperature greater than 1000°C by the electric heating mechanism 132 of the melting and heating section 13. The hot reducing gas flows in a reverse direction from the hot reducing gas outlet 131 of the melting and heating section 13 through the hot reducing gas pipeline and enters the reduction section 12 through the hot reducing gas inlet 124 of the reduction section 12. The hot reducing gas reacts with the iron ore entering the reduction section 12 at a temperature of 1100°C to produce sponge iron, water, and top gas. In this embodiment, the metallization of the sponge iron is 30% to 95% and the temperature is 650°C.

[0073] The top gas and water enter the heat exchanger 21 of the process gas recovery pipeline 2 through the top gas outlet 123 of the reduction section 12, where they are mixed with the hydrogen injected from the hydrogen injection pipe 31 to form a mixed gas for heat exchange and pre-cooling, and then enter the scrubber 22 for cooling and dust removal, and then enter the desulfurizer 23 to remove hydrogen sulfide and organic sulfur to obtain purified top gas. The sponge iron enters the melting and heating section 13 through the sponge iron discharge pipe 121 of the reduction section 12. In this embodiment, the desulfurizer 23 can adopt dry desulfurization or wet desulfurization. The sulfur content of the top gas after desulfurization is less than or equal to 10 ppmv, and the metallization rate of the melting and heating section 13 is greater than 95%.

[0074] The purified top gas is mixed with the hydrogen in the hydrogen injection pipe 31 injected into the hydrogen injection pipeline 3 to form a mixed gas, which is preheated by the heat exchanger 21 and then injected into the molten iron layer in the melting and heating section 13 by the hydrogen spray gun 32 connected to the end of the hydrogen injection pipe 31. In the present invention, an electric heating mechanism 132 is provided on the outside of the melting and heating section 13. The mixed gas in the molten iron layer in the melting and heating section 13 can be quickly heated into hot reducing gas that can be sent to the reduction section 12 under the heating of the electric heating mechanism 132.

[0075] In the present invention, a flux spray gun 133 is further provided on the melting and heating section 13. The sponge iron from the reduction section 12 is fed into the melting and heating section 13 through the sponge iron discharge pipe 121. Under the action of the heating of the electric heating mechanism 132 and the flux injected by the flux spray gun 133, the sponge iron undergoes a reduction reaction with the hydrogen in the mixed gas injected into the molten iron layer by the hydrogen spray gun 32, and the sponge iron is converted into slag and molten molten iron. In this embodiment, the molten iron generated in the melting and heating section 13 enters the molten iron tank 136 from the molten iron outlet 135 and is intermittently sent to the next section to participate in the subsequent steelmaking process, and the slag is continuously discharged through the slag outlet 134.

[0076] According to one embodiment of the present invention, the top gas is pre-cooled by the heat exchanger 21, and the temperature of the top gas after cooling and dust removal by the scrubber 22 is 30°C to 50°C. The purified top gas is mixed with the hydrogen injected into the hydrogen injection pipe 31 to form a mixed gas. The temperature of the mixed gas after preheating by the heat exchanger 21 is 200°C to 500°C.

[0077] In this embodiment, the top gas and the mixed gas exchange heat in the heat exchanger 21, the top gas is quickly pre-cooled before purification, and the mixed gas is quickly preheated before entering the melting heating section 13, thereby fully utilizing the thermal energy of the top gas and promoting the generation rate of hot reducing gas.

[0078] Specifically, such as Figure 3 As shown, the temperature of the top gas coming out of the reduction section 12 is 300°C to 500°C. After being pre-cooled by the heat exchanger 21 and cooled and dust-removed by the scrubber 22, the temperature is reduced to 30°C to 50°C. The top gas purified by the process gas recovery pipeline 2 is mixed with the hydrogen injected into the hydrogen injection pipe 31 to form a mixed gas with a temperature of the ambient temperature. After being preheated by the heat exchanger 21, the temperature is raised to 200°C to 500°C.

[0079] According to another embodiment of the present invention, a dehydrator 24 is provided at the downstream end of the desulfurizer 23 along the gas flow direction in the process gas recovery pipeline 2, and a pressurizing mechanism 25 is provided at the downstream end of the dehydrator 24; wherein, the purified furnace top gas is dehydrated by the dehydrator 24 to become process gas, and after the process gas is pressurized by the pressurizing mechanism 25, it is mixed with hydrogen at the inlet end of the hydrogen injection pipe 31 to form a mixed gas, and the hydrogen content in the mixed gas accounts for more than 55%.

[0080] In this embodiment, the obtained process gas is dry, which can extend the service life of subsequent facilities to a certain extent. The process gas pressurized by the pressurizing mechanism 25 is more likely to flow into the melting and heating section 13 of the molten iron vertical furnace 1 through the hydrogen injection pipe 31 for recycling. Figure 1 As shown, along the gas flow direction in the process gas recovery pipeline 2, a dehydrator 24 is provided at the downstream end of the desulfurizer 23, and a pressurizing mechanism 25 is provided at the downstream end of the dehydrator 24, that is, the outlet of the desulfurizer 23 is connected to the dehydrator 24, and the outlet of the dehydrator 24 is connected to the pressurizing mechanism 25; wherein, the purified furnace top gas is dehydrated by the dehydrator 24 to become process gas, and the process gas is pressurized by the pressurizing mechanism 25 and mixed with hydrogen at the inlet end of the hydrogen injection pipe 31 to form a mixed gas, and the hydrogen content in the mixed gas accounts for more than 55%, preferably, the hydrogen content in the mixed gas accounts for more than 90%, and in this embodiment, the dehydrator 24 adopts one or more combinations of centrifugal separation, adsorption dehydration, and freeze dehydration.

[0081] The above is only one embodiment of the present invention. Those skilled in the art may make various changes or modifications to the embodiment of the present invention based on the contents disclosed in the application documents without departing from the spirit and scope of the present invention.

Claims

1. A full hydrogen ironmaking system, characterized in that: include: A molten iron vertical furnace having a feeding section, a reduction section, and a melting and heating section connected from top to bottom; wherein the melting and heating section has at least one hot reducing gas outlet, and at least one of the hot reducing gas outlets is connected to the reducing section; A process gas recovery pipeline is connected to the molten iron vertical furnace, and the process gas recovery pipeline has a heat exchanger, a scrubber and a desulfurizer connected in sequence; A hydrogen injection pipeline having a connected hydrogen injection pipe and at least one hydrogen spray gun, wherein the hydrogen injection pipe is connected to the heat exchanger, and at least one hydrogen spray gun extends into the melting and heating section; The reduction section has a sponge iron feeding pipe, which can extend into the melting and heating section, and the sponge iron feeding pipe is connected to a switch valve; An electric heating mechanism is provided on the outside of the melting and heating section, and a refractory material layer is provided between the electric heating mechanism and the melting and heating section.

2. The all-hydrogen ironmaking system according to claim 1, characterized in that: The process gas recovery pipeline further comprises a dehydrator, and along the gas flow direction in the process gas recovery pipeline, the dehydrator is located at the downstream end of the desulfurizer.

3. The all-hydrogen ironmaking system according to claim 2, characterized in that: The process gas recovery pipeline also has a pressurizing mechanism, which is located at the downstream end of the dehydrator along the gas flow direction in the process gas recovery pipeline and is connected to the inlet end of the hydrogen injection pipe.

4. The all-hydrogen ironmaking system according to claim 1, characterized in that: The heat exchanger has a cold medium inlet and a cold medium outlet, and the cold medium inlet and the cold medium outlet are respectively connected to the hydrogen injection pipe.

5. The all-hydrogen ironmaking system according to claim 1, characterized in that: The melting and heating section is provided with a plurality of flux spray guns, which are arranged at intervals along the circumferential direction of the melting and heating section and can extend into the slag layer in the melting and heating section.

6. The all-hydrogen ironmaking system according to claim 5, characterized in that: The flux injected into the flux spray gun is one or a combination of lime, limestone and dolomite.

7. The all-hydrogen ironmaking system according to claim 1, characterized in that: There are multiple hydrogen spray guns, which are arranged at intervals along the circumferential direction of the melting and heating section and can extend into the molten iron layer in the melting and heating section.

8. The all-hydrogen ironmaking system according to claim 1, characterized in that: The reaction temperature of the melting and heating section is greater than 1500° C., and the pressure of the hydrogen injected into the melting and heating section is greater than 0.1 MPa.

9. A full hydrogen ironmaking method, characterized in that: The method is implemented using the full hydrogen ironmaking system according to any one of claims 1 to 8, comprising the following steps: feeding iron ore into the feed section of the molten iron shaft furnace, wherein the iron ore reacts with the hot reducing gas injected into the reducing section to produce sponge iron, water and top gas; The top gas and the water enter the heat exchanger of the process gas recovery pipeline, are pre-cooled by the heat exchanger, are passed into the scrubber for cooling and dust removal, and are then passed into the desulfurizer for desulfurization to obtain purified top gas; the sponge iron passes through the reduction section and settles into the melting and heating section; The purified top gas is mixed with hydrogen injected into the hydrogen injection pipe of the hydrogen injection pipeline, and after being preheated by the heat exchanger, is injected into the molten iron layer of the melting and heating section through the hydrogen lance to generate hot reducing gas that is transported to the reduction section; The sponge iron undergoes a reduction reaction with the hydrogen injected into the melting and heating section to generate molten iron and slag.

10. The all-hydrogen ironmaking method according to claim 9, characterized in that: The temperature of the furnace top gas after cooling through the heat exchanger and the scrubber is 30°C to 50°C. The purified furnace top gas is mixed with the hydrogen injected into the hydrogen injection pipe to form a mixed gas. The temperature of the mixed gas after preheating through the heat exchanger is 200°C to 500°C.

11. The all-hydrogen ironmaking method according to claim 9, characterized in that: Along the gas flow direction in the process gas recovery pipeline, a dehydrator is provided at the downstream end of the desulfurizer, and a pressurizing mechanism is provided at the downstream end of the dehydrator; wherein, the purified furnace top gas is dehydrated by the dehydrator to become process gas, and after the process gas is pressurized by the pressurizing mechanism, it is mixed with hydrogen at the inlet end of the hydrogen injection pipe to form a mixed gas, and the hydrogen content in the mixed gas accounts for more than 55%.

12. The all-hydrogen ironmaking method according to claim 9, characterized in that: The metallization rate of the reduction section is greater than 30%, and the metallization rate of the melting and heating section is greater than 95%.

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