A device for enriching and recycling smelting reduction furnace gas

Abstract

The application relates to a device for enriching and recycling smelting reduction furnace gas, belonging to the technical field of iron oxide smelting reduction. The device solves the problems of high CO2 content and low calorific value of the furnace top gas. The device comprises a smelting reduction furnace, a vaporization cooling flue, a gas purification device, a CO2 removal device, a gas pressurizing device 5, a CO2 storage tank 6 and the like; the first five components are sequentially connected, the gas pressurizing device is connected with a gas injection lance and a gas heating device respectively; the CO2 removal device is connected with the CO2 storage tank and a CO2 pressurizing device respectively, and the CO2 pressurizing device and a material outlet of an iron-containing material preheating and pre-reducing device are connected with a solid material injection lance through a material injection system. The use method comprises the following steps: after the gas is cooled and purified through the vaporization cooling flue and the gas purification device, the CO2 in the gas is separated out through the CO2 removal device, then the gas is pressurized to 300-1000 kPa through the gas pressurizing device, the separated CO2 gas is pressurized to 600-1000 kPa through the CO2 pressurizing device, and finally the gas is injected into the smelting reduction furnace. The device has the advantages that low-calorific-value gas enrichment is realized, the enriched gas can be used for preheating and pre-reducing iron-containing materials, and CO2 recycling and utilization are realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of iron oxide smelting reduction, and particularly relates to a device for enriching and recycling coal gas of a smelting reduction furnace. BACKGROUND

[0002] Modern blast furnace ironmaking technology has been developed for more than 200 years, and the process technology is becoming mature. The production efficiency, energy consumption and service life of the blast furnace have achieved good application results, and the blast furnace is still the most important ironmaking process device. The biggest challenge of blast furnace ironmaking is that it cannot get rid of the dependence on coke. Coke has four functions in the blast furnace, namely, heat generating agent, reducing agent, carburizing agent and column skeleton, especially the function of column skeleton, which cannot be replaced by other materials. In other words, coke becomes the material and energy basis for the survival of the blast furnace. In addition, the blast furnace ironmaking process needs to process the raw materials to process the iron ore powder into artificial ore such as pellet and sinter, and needs to have excellent physical properties and high temperature metallurgical properties to meet the requirements of blast furnace production. Therefore, the modern blast furnace must be equipped with coking, sintering, pelletizing and other iron-making process devices to prepare artificial ore and coke as raw materials and fuel for the blast furnace.

[0003] Statistics show that the energy consumption of the iron-making process of the blast furnace production process accounts for about 70%-85% of the entire steel manufacturing process, the pollutant emission of the iron-making process accounts for more than 70%, and the CO2 emission accounts for more than 75%. Therefore, the smelting reduction process using powder flow and completely canceling coke has significant advantages: the coking, sintering, pelletizing and other iron-making processes can be completely canceled, the natural iron ore powder can be directly used to replace the sinter or pellet, and the coal powder can be used to replace the coke. In the smelting reduction reactor, molten iron is produced through high temperature smelting. This full powder flow smelting reduction process can significantly reduce the emissions of particulate matter, SO x , NO x , reduce the energy consumption of the iron-making process, has significant CO2 emission technical advantages and potential, and is the main technical development direction of future non-blast furnace low-carbon green metallurgy and hydrogen metallurgy.

[0004] In the existing smelting reduction process, the heat value of the top gas is low, and it can only be used as a general industrial gas fuel and cannot be fully utilized. Moreover, due to the high direct carbon consumption in the smelting reduction process, the volume percentage of CO2 in the top gas is generally more than 25%, and the CO2 emission intensity of the unit process is high. SUMMARY

[0005] The purpose of this invention is to provide a device for enriching and recycling molten reduction furnace gas, and to solve the key technical defects of the existing molten reduction process: (1) high CO2 volume percentage in the furnace top gas, low calorific value of the gas, and large emission of CO2 without separation and removal treatment; (2) insufficient pre-reduction of ore powder, low pre-reduction rate, and high direct carbon consumption in the molten reactor; (3) using N2 as the carrier gas for ore powder and coal powder, resulting in high N2 volume percentage and low calorific value of metallurgical gas; (4) in the molten reduction metallurgical reactor, the high temperature zone is located in the upper part of the reactor, resulting in low efficiency of the heat transfer mechanism to the lower molten pool and insufficient heat in the furnace hearth.

[0006] A device for enriching and recycling molten reduction furnace gas includes: a molten reduction furnace 1, a vaporization cooling flue 2, a gas purification device 3, a CO2 removal device 4, a gas pressurization device 5, a CO2 storage tank 6, a CO2 pressurization device 7, a solid material spray gun 8, a gas spray gun 9, an oxygen spray gun 10, a gas heating device 11, and an iron-containing material preheating and pre-reduction device 12; the gas outlet of the molten reduction furnace 1 is sequentially connected to the vaporization cooling flue 2, the gas purification device 3, the CO2 removal device 4, and the gas pressurization device 5. The gas outlet of the gas pressurizing device 5 is connected to the gas spray gun 9 and the inlet of the gas heating device 11, respectively. The inlet of the gas heating device 11 is connected to the gas inlet of the iron-containing material preheating and pre-reduction device 12. The CO2 outlet of the CO2 removal device 4 is connected to the inlet of the CO2 storage tank 6 and the inlet of the CO2 pressurizing device 7, respectively. The outlet of the CO2 pressurizing device 7 and the material outlet of the iron-containing material preheating and pre-reduction device 12 are connected to the solid material spray gun 8 through the material blowing system. The oxygen spray gun 10 is connected to the melting reduction furnace 1 through a flange.

[0007] The operating method and parameters of the device for enriching and recycling molten reduction furnace gas are as follows:

[0008] 1. The gas from the molten reduction furnace 1 is cooled and purified by the vaporization cooling flue 2 and the gas purification device 3. Then, the CO2 in the gas is separated by the CO2 removal device 4. As the volume percentage of CO in the gas increases, the corresponding calorific value and reduction potential increase.

[0009] 2. After CO2 is removed by the CO2 removal device 4, the gas is pressurized by the gas pressurization device 5 to a pressure of 300-1000 kPa. Part of the gas is sent to the gas heating device 11 through the gas pipeline for heating. The heated gas is used as the reducing gas in the iron-containing material preheating and pre-reduction device 12. The rest is injected into the melting reduction furnace 1 through the gas spray gun 9. After mixing with the oxygen injected into the furnace by the oxygen spray gun 10, the gas is burned and released heat to provide heat to the reaction pool. There are 1-4 gas spray guns 9, which are evenly distributed in the horizontal direction on the inner surface of the upper furnace wall of the melting reduction furnace 1. The insertion length and angle can be adjusted.

[0010] 3. The CO2 gas separated from the coal gas is pressurized by the CO2 pressurizing device 7 to a pressure of 600-1000 kPa. Part of it is used as carrier gas for solid material injection. After passing through the conveying pipeline and injection system, the iron-containing material treated by the iron-containing material preheating and pre-reduction device 12 is finally injected into the melting reduction furnace 1 along with coal powder and flux through the solid material spray gun 8. The excess CO2 is sent out through the CO2 storage tank 6.

[0011] The CO2 removal device 4 described in step 1 removes CO2 using physical or chemical methods;

[0012] In step 1, the CO2 gas separated from the coal gas has a CO2% volume percentage greater than 85%.

[0013] The gas purification device 3 described in step 1 uses either wet gas dust removal or dry gas bag filter dust removal.

[0014] The oxygen injected into the furnace by the oxygen lance 10 in step 2 is pure oxygen or oxygen-enriched hot air. When the oxygen-enriched hot air is injected, the oxygen content of the hot air is 35%-42% by volume.

[0015] The iron-containing material preheating and pre-reduction device 12 described in step 3 adopts a fluidized bed, gas-based vertical shaft furnace, or other process devices with the same function;

[0016] The degree of pre-reduction of the iron-containing material treated by the iron-containing material preheating and pre-reduction device 12 in step 3 is 10%-95%;

[0017] The volume percentage of (CO+H2) in the coal gas after CO2 removal by the CO2 removal device 4, as described in step 2, is 30-90%.

[0018] The advantages of this invention are:

[0019] 1) By removing CO2 from the molten reduction furnace gas, CO2 can be separated and removed for capture, storage or reuse (CCUS). On the other hand, the top gas can be modified and enriched, which can enrich the low-calorific-value gas. The enriched gas can be used for preheating and pre-reduction of iron-containing materials, which can realize the efficient utilization of high-temperature low-calorific-value gas, which is conducive to improving the smelting efficiency of the molten reduction furnace and reducing energy consumption.

[0020] 2) It adopts mature CO2 removal technology, with a simple process flow, low investment, and stable and reliable operation;

[0021] 3) By using CO2 separated from the gas of the molten reduction furnace to replace nitrogen and as the carrier gas for transporting ore powder and coal powder in the molten reduction furnace, CO2 can be recycled, thereby achieving CO2 emission reduction. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a device for enriching and recycling gas from a molten reduction furnace. The device includes: 1. Molten reduction furnace; 2. Vaporization cooling flue; 3. Gas purification device; 4. CO2 removal device; 5. Gas pressurization device; 6. CO2 storage tank; 7. CO2 pressurization device; 8. Solid material spray gun; 9. Gas spray gun; 10. Oxygen spray gun; 11. Gas heating device; and 12. Iron-containing material preheating and pre-reduction device. Detailed Implementation

[0023] like Figure 1 As shown, an apparatus for enriching and recycling molten reduction furnace gas includes: a molten reduction furnace 1, a vaporization cooling flue 2, a gas purification device 3, a CO2 removal device 4, a gas pressurization device 5, a CO2 storage tank 6, a CO2 pressurization device 7, a solid material spray gun 8, a gas spray gun 9, an oxygen spray gun 10, a gas heating device 11, and an iron-containing material preheating and pre-reduction device 12; the gas outlet of the molten reduction furnace 1 is sequentially connected to the vaporization cooling flue 2, the gas purification device 3, the CO2 removal device 4, and the gas pressurization device 5. The gas outlet of the gas pressurizing device 5 is connected to the gas spray gun 9 and the inlet of the gas heating device 11, respectively. The inlet of the gas heating device 11 is connected to the gas inlet of the iron-containing material preheating and pre-reduction device 12. The CO2 outlet of the CO2 removal device 4 is connected to the inlet of the CO2 storage tank 6 and the inlet of the CO2 pressurizing device 7, respectively. The outlet of the CO2 pressurizing device 7 and the material outlet of the iron-containing material preheating and pre-reduction device 12 are connected to the solid material spray gun 8 through the material blowing system. The oxygen spray gun 10 is connected to the melting reduction furnace 1 through a flange.

[0024] The gas from the molten reduction furnace 1 is cooled and purified by the vaporization cooling flue 2 and the gas purification device 3. Then, CO2 is separated from the gas by the CO2 removal device 4. Part of the gas after CO2 removal is pressurized to 800 kPa by the gas pressurization device 5, and part is sent to the gas heating device 11 for heating via a gas pipeline. The gas heated to 970℃ is used as the reducing gas in the iron-containing material preheating and pre-reduction device 11, which employs a gas-based vertical shaft furnace process. The other part of the gas is injected into the molten reduction furnace 1 through the gas injection gun 9. There are two lances 9, symmetrically distributed horizontally on the inner surface of the upper furnace wall of the molten reduction furnace 1. CO2 gas (95% CO2) separated from the coal gas is pressurized to 900 kPa by the CO2 pressurizing device 7. A portion of this gas is used as carrier gas for solid material injection, connected to the injection system via a conveying pipeline. The iron-containing material, treated by the iron-containing material preheating and pre-reduction device 12, along with pulverized coal and flux, is injected into the molten reduction furnace 1 through the solid material injection lance 8. The pre-reduction degree of the iron-containing material is 80%. Excess CO2 is sent out through the CO2 storage tank 6. The oxygen-containing gas injected into the furnace through the oxygen injection lance 10 has an oxygen content of 95%.

Claims

1. A device for enriching and recycling molten reduction furnace gas, characterized in that, The apparatus includes a molten reduction furnace (1), a vaporization cooling flue (2), a gas purification device (3), a CO2 removal device (4), a gas pressurization device (5), a CO2 storage tank (6), a CO2 pressurization device (7), a solid material spray gun (8), a gas spray gun (9), an oxygen spray gun (10), a gas heating device (11), and an iron-containing material preheating and pre-reduction device (12); the gas outlet of the molten reduction furnace (1) is sequentially connected to the vaporization cooling flue (2), the gas purification device (3), the CO2 removal device (4), and the gas pressurization device (5), and the gas pressurization device is... The gas outlet of device (5) is connected to the gas spray gun (9) and the inlet of the gas heating device (11) respectively. The inlet of the gas heating device (11) is connected to the gas inlet of the iron-containing material preheating and pre-reduction device (12). The CO2 outlet of CO2 removal device (4) is connected to the inlet of CO2 storage tank (6) and the inlet of CO2 pressurization device (7) respectively. The outlet of CO2 pressurization device (7) and the material outlet of iron-containing material preheating and pre-reduction device (12) are connected to the solid material spray gun (8) through the material blowing system. The oxygen spray gun (10) is connected to the melting reduction furnace (1) through a flange.

2. The method of using the apparatus for enriching and recycling molten reduction furnace gas according to claim 1, characterized in that, The steps and parameters are as follows: 1) The gas from the molten reduction furnace (1) is cooled and purified by the vaporization cooling flue (2) and the gas purification device (3). Then, the CO2 in the gas is separated by the CO2 removal device (4). As the volume percentage of CO in the gas increases, the corresponding calorific value and reduction potential increase. 2) After CO2 is removed by the CO2 removal device (4), the gas pressure is 300-1000 kPa after being pressurized by the gas pressurization device (5). Part of the gas is sent to the gas heating device (11) through the gas pipeline for heating. The heated gas is used as the reducing gas of the iron-containing material preheating and pre-reduction device (12). The rest is injected into the melting reduction furnace (1) through the gas spray gun (9). After mixing with the oxygen injected into the furnace by the oxygen spray gun (10), the gas is burned and released heat to provide heat to the reaction pool. There are 1-4 gas spray guns (9), which are evenly distributed on the inner surface of the upper furnace wall of the melting reduction furnace (1) in the horizontal direction. The insertion length and angle can be adjusted. 3) The CO2 gas separated from the coal gas is pressurized by the CO2 pressurizing device (7) to a pressure of 600-1000 kPa. Part of it is used as carrier gas for solid material injection. After passing through the conveying pipeline and injection system, the iron-containing material treated by the iron-containing material preheating and pre-reduction device (12) is finally injected into the melting reduction furnace (1) along with coal powder and flux through the solid material spray gun (8). The excess CO2 is sent out through the CO2 storage tank (6).

3. The method according to claim 2, characterized in that, The CO2 removal device (4) described in step 1) removes CO2 using physical or chemical methods.

4. The method according to claim 2, characterized in that, In step 1), the CO2 gas separated from the coal gas has a CO2% volume percentage greater than 85%.

5. The method according to claim 2, characterized in that, The gas purification device (3) described in step 1) uses wet gas dust removal or dry gas bag filter dust removal.

6. The method according to claim 2, characterized in that, In step 2), the oxygen injected into the furnace by the oxygen lance (10) is pure oxygen or oxygen-enriched hot air. When the oxygen-enriched hot air is injected, the oxygen content of the hot air is 35%-42% by volume.

7. The method according to claim 2, characterized in that, The volume percentage of CO+H2 in the gas after CO2 removal by the CO2 removal device (4) in step 2) is 30-90%.

8. The method according to claim 2, characterized in that, The iron-containing material preheating and pre-reduction device (12) described in step 3) adopts a fluidized bed or gas-based vertical furnace.

9. The method according to claim 2, characterized in that, The pre-reduction degree of the iron-containing material processed by the iron-containing material preheating and pre-reduction device (12) in step 3) is 10%-95%.

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