Method for blowing decarbonized gas and coke oven gas by using hydrogen-enriched carbonic oxide recycling oxygenate furnace

Abstract

Disclosed is a method for blowing decarbonized gas and coke oven gas by using a hydrogen-enriched carbonic oxide recycling oxygenate furnace. The present invention changes the blending method, upgrading the blending of coke oven gas from a low-temperature section of the gas to a high-temperature section. The coke oven gas is improved and optimized over the existing technology and is used, without passing through a gas heating furnace, as mixed gas after heating decarbonized gas of a hydrogen-enriched carbonic oxide recycling oxygenate furnace. Thus, hydrogen-rich gas can also increase in temperature and be blown into the furnace to participate in a reduction process without passing through a gas heating furnace. Meanwhile, the present invention also avoids the disadvantage that hydrogen-rich gas H2 in the coke oven gas reacts with SiO2 in a refractory material after passing through the gas heating furnace, which would degrade the performance of the refractory material.

Description

Method for injecting decarbonized coal gas and coke oven gas into hydrogen-rich carbon circulating oxygen blast furnace Technical Field

[0001] The invention belongs to a gas injection technology for a low-carbon blast furnace, and in particular relates to a method for injecting decarbonized gas and coke oven gas into a hydrogen-rich carbon circulating oxygen blast furnace. Background Art

[0002] The Hydrogen-Rich Carbon Recycled Oxygen Blast Furnace (HyCROF) uses oxygen blast instead of traditional heated air blast, and removes CO2 from the furnace top gas to form a gas medium with a higher concentration of reducing components (CO and H2). At the same time, it is mixed with natural gas and coke oven gas containing reducing gases CH4 and H2. It needs to be heated and then recycled and sprayed into the tuyere of the Hydrogen-Rich Carbon Recycled Oxygen Blast Furnace (HyCROF), and then used as an ironmaking process to reduce carbon and solid fuel. The injection of decarbonized circulating gas and coke oven gas is the core technology of the Hydrogen-Rich Carbon Circulating Oxygen Blast Furnace (HyCROF). When the coke oven gas is heated in a gas heater, the refractory bricks in the high-temperature zone of the dome of the HyCROF gas heater are made of silica bricks with a SiO2 content of 90-95%. Because silica bricks contain a large amount of SiO2, they will produce the reaction SiO2+H2=SiO(g)↑+H2O at high temperatures. In long-term use, there will be weight loss and strength attenuation problems, which greatly affect the stability and safety of the silica bricks in the high-temperature zone of the dome. The specific process is shown in Figure 1 for the injection process of decarbonized coal gas and coke oven gas. Summary of the Invention

[0003] The object of the present invention is to provide a method for injecting decarbonized coal gas and coke oven gas into a hydrogen-rich carbon circulating oxygen blast furnace, which can stably control the temperature of the coal gas injected into the hydrogen-rich carbon circulating oxygen blast furnace, stabilize the temperature and composition of the injected coal gas, and can reduce CO2 emissions by more than 18% and reduce solid fuel consumption by more than 30%.

[0004] The present invention provides a method for injecting decarbonized coal gas and coke oven gas into a hydrogen-rich carbon circulating oxygen blast furnace, and the implementation steps are as follows:

[0005] This method relies on a hydrogen-rich carbon-circulating oxygen blast furnace, and serves as the primary means for adjusting the gas injection temperature and composition. The hydrogen-rich carbon-circulating oxygen blast furnace, a metallurgical facility, primarily uses solid fuels and gaseous fuels as its charge. The solid fuels primarily include coke and injected coal, while the gaseous fuel primarily consists of decarbonized gas containing reducing CO and H2, removed from the top gas, and coke oven gas. The charge's ore composition primarily utilizes alkaline, acidic, and natural lump ores.

[0006] The fuel consumption of the charge is: solid fuel coke 250-280kg / tHM, injection coal 40-80kg / tHM; the decarbonized coal gas injection circulation volume of the gas fuel is 450-750Nm 3 / tHM, coke oven gas injection consumption is 50-150Nm 3 / tHM.

[0007] The decarbonized coal gas described in this method is heated in a gas heating furnace and then blended with coke oven gas at the furnace outlet. The blended medium has a temperature of 1100-1250°C and contains the following main components by volume: CO: 55-60%, H2: 12-25%, N2: 3-5%, CO2: 0-3%, and CH4: 8-10%. The high-temperature coal gas blended with the decarbonized coal gas in this step is injected into the furnace via a composite injection device. The decarbonized coal gas pressure is controlled at 0.35-0.4 MPa.

[0008] The decarbonized coal gas described in the method is heated by a coal gas heating furnace, and at the outlet of the coal gas heating furnace, it has the function of introducing 40°C mixed cold decarbonized coal gas and coke oven gas before being added to the coal gas heating furnace separately or mixed.

[0009] Further adding ambient temperature coke oven gas (COG) to the hot gas pipeline after the gas heater is a functional improvement method based on solving the disadvantages of coke oven gas entering the high temperature area of ​​the gas heater vault. The coke oven gas H2 reacts with SiO2 at high temperature, resulting in weight loss and strength loss. Taking the injection temperature of 1200℃ as an example, the specific addition of ambient temperature coke oven gas, decarbonized gas temperature of 40℃, and average specific heat capacity of 1.371 kJ / Nm 3 .℃, coke oven gas 25℃, average specific heat capacity 1.369 kJ / Nm 3 .℃; when the room temperature coke oven gas and decarbonized gas are mixed and the injection temperature of the mixed medium needs to reach the injection temperature of 1200℃, the decarbonized gas flow rate is increased from 20000 Nm 3 / h increased by 190000Nm 3 / h, the heat required to heat the temperature from 40℃ to 1200℃ increases from 30.3GJ to 288GJ; the coke oven gas flow rate increases from 1000 Nm 3 / h increased by 14600Nm 3 / h, the heat required to heat the temperature from 25°C to 1200°C increased from 1.6GJ to 23.5GJ; the total heat of the mixed coke oven gas and decarbonized gas increased from 31.9GJ to 311.5GJ; in order to maintain the mixed medium temperature at 1200°C after mixing, the actual outlet temperature of the gas heater increased from 1261.7°C to 1294.8°C. The specific adjustment parameter calculation model is shown in the table below:

[0010] .

[0011] The specific method for blending and adding coke oven gas (COG) is achieved through a COG blending and adding device. Taking an injection temperature of 1200°C as an example, the system primarily includes a COG flow control device, pressure detection, flow detection, temperature detection, flow cut-off device, gas heater outlet temperature, pressure, and flow detection, post-blending temperature detection, and safety devices. The specific process flow and operation are as follows: Top gas from a hydrogen-rich carbon-recycled oxygen blast furnace passes through a dust removal and dehydration device, and is pressurized to 0.45-1.6 MPa by a compressor. It then enters a decarbonization device to remove CO2, forming a gas medium with a 65-85% volume fraction of reducing components (CO and H2). After pressure, temperature, and flow detection, it enters a gas heater, is heated to above 1200°C, and then injected into the lower hearth of the hydrogen-rich carbon-recycled oxygen blast furnace using a composite injection device.

[0012] Furthermore, in order to maintain the stability of the injected coal gas temperature, the temperature fluctuation is ±5-10℃. 40℃ mixed cold decarbonized coal gas is introduced before entering the gas heating furnace and mixed into the heated hot gas pipeline system to stabilize the temperature injected into the furnace at 1200℃.

[0013] Furthermore, in order to increase the reducing components (CO and H2) in the injected gas, the CH4 with a volume fraction of 22-24% in the coke oven gas can be decomposed or cracked into CO and H2, while also having a volume fraction of CO+H2 of 55-60%. At the same time, the stability of the injected gas temperature is maintained, with a temperature fluctuation of ±5-10°C. The optimized coke oven gas is mixed and added to the heated hot gas pipeline system to stabilize the temperature injected into the furnace at 1200°C, and the pressure of the coke oven gas is 50-100kPa higher than the pressure of the hot decarbonized gas.

[0014] Preferably, the flow rate of coke oven gas is fixed at 1000-14600 Nm 3 / h, and adjust the flow control device of the 40℃ mixed cold decarbonized coal introduced into the gas heating furnace to stabilize the temperature of the coal injected into the furnace at 1200℃.

[0015] Preferably, the flow regulating device is adopted to adjust the mixing flow of coke oven gas to 1000-14600Nm 3 / h, if the mixing flow of coke oven gas is adjusted to 14600Nm 3 / h, the temperature injected into the furnace is higher than 1200℃. The flow regulating device of the mixed cold decarbonized coal gas at 40℃ introduced before the gas heating furnace can be adjusted to stabilize the temperature injected into the furnace at 1200℃.

[0016] Furthermore, the interlocking requirement for blending and adding is that the pressure of coke oven gas is 30-40 kPa lower than the pressure of thermal decarbonization gas, and two flow cut-off devices are automatically closed to cut off the blending and adding. The safety device is to inject N2 between the flow cut-off devices while cutting off the natural gas source and the coke oven gas source.

[0017] The raw materials and coke of the hydrogen-rich carbon cycle oxygen blast furnace are weighed by a dosing device, and the batch iron content, theoretical coke ratio, and slag basicity are calculated. The ore mass fraction of the raw materials includes 40-55% alkaline ore, 40-50% acidic ore, 5-10% natural lump ore, and 250-280kg / tHM of coke.

[0018] The raw fuels, alkaline ore, acidic ore, natural lump ore and coke are added in layers from the feeding device on the furnace top. The injection coal, decarbonized coal gas and coke oven gas are injected into the furnace from the composite injection device at the bottom of the furnace. At the same time, the composite injection device also injects industrial oxygen into the furnace. The oxygen content is 90-99.9% of room temperature cold oxygen, and the oxygen amount is controlled at 160-230Nm 3 / tHM, the hydrogen-rich carbon circulating oxygen blast furnace finally produces qualified molten iron, by-product gas and slag.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The present invention prevents the reaction of SiO2 in the refractory bricks in the high-temperature zone of the dome of a hydrogen-rich carbon circulating oxygen blast furnace (HyCROF) gas heating furnace with H2 in the coke oven gas and natural gas when the gas heating furnace is heating and injecting coke oven gas. This reaction will cause weight loss and strength attenuation in long-term use, greatly affecting the stability and safety of the silica bricks in the high-temperature zone of the dome.

[0021] 2. The present invention can stably control the temperature of the gas injected into the hydrogen-rich carbon circulating oxygen blast furnace, stabilize the temperature and composition of the injected gas, reduce CO2 emissions by more than 18%, and reduce solid fuel consumption by more than 30%, thus having a certain greenhouse gas emission reduction effect.

[0022] 3. The present invention changes the mixing method, upgrading the coke oven gas from the low-temperature end to the high-temperature end. Since the gas has the characteristics of combustion, explosion, and poisoning, the low-temperature end does not need to consider the impact of its characteristics on intrinsic safety. However, this technology mixes from the high-temperature end, which requires research and design on the correlation between combustion, explosion, poisoning and intrinsic safety production. Therefore, this technology designs high-temperature interlocking pressure protection, nitrogen safety, and accident quick cut-off in hardware, and develops models for composition, flow and heat calculation in software, which has certain creativity and innovation. Technical Solution BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG1 is a schematic diagram of the process flow before optimization of the present invention;

[0024] FIG2 is a schematic diagram of the process flow after optimization of the present invention.

[0025] Specific markings in the figure: 1-hydrogen-rich carbon circulating oxygen blast furnace; 2-coke oven gas source; 3-first coke oven gas flow cut-off device; 4-coke oven gas temperature detection device; 5-coke oven gas pressure detection device; 6-coke oven gas flow detection device; 7-coke oven gas flow regulating device; 8-second coke oven gas flow cut-off device; 9-top gas compressor; 10-decarbonization device; 11-gas heating furnace; 12-first cold decarbonization gas flow cut-off device; 13-cold decarbonization gas temperature detection device; 14-cold decarbonization gas pressure detection device; 15-cold decarbonization gas flow detection device; 16-cold decarbonization gas flow regulating device; 17-second cold decarbonization gas flow cut-off Device; 18-temperature detection device for cold decarbonized coal gas entering the heating furnace; 19-pressure detection device for cold decarbonized coal gas entering the heating furnace; 20-flow detection device for cold decarbonized coal gas entering the heating furnace; 21-N2 gas source device; 22-N2 first cut-off device; 23-N2 second cut-off device; 24-temperature detection device for hot decarbonized coal gas; 25-pressure detection device for hot decarbonized coal gas; 26-flow detection device for hot decarbonized coal gas; 27-temperature detection device for hot mixed medium; 28-composite injection device; 29-raw fuel furnace top adding device (for adding alkaline ore, acidic ore, natural lump ore and coke); 30-dust removal and dehydration device; 31-oxygen gas source device; 32-coal injection device. DETAILED DESCRIPTION

[0026] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention rather than limiting the patent claims of the present invention.

[0027] Embodiment: Referring to Figure 2 in conjunction with Figure 1, a method for injecting decarbonized coal gas and coke oven gas into a hydrogen-rich carbon circulating oxygen blast furnace is provided. The top coal gas of the hydrogen-rich carbon circulating oxygen blast furnace 1 passes through a dust removal and dehydration device 30, and is pressurized to 0.45-1.6 MPa by a top gas compressor 9. The top coal gas then enters a decarbonization device 10 to remove CO2, forming a coal gas medium with a volume fraction of 65-85% of reducing components (CO and H2). After passing through the cold decarbonized coal gas temperature detection 18 entering the heating furnace, the cold decarbonized coal gas pressure detection 19 entering the heating furnace, and the cold decarbonized coal gas flow detection 20 entering the heating furnace, the coal gas enters the gas heating furnace 11 and is heated to above 1200°C. The coal gas is then injected into the lower furnace hearth of the hydrogen-rich carbon circulating oxygen blast furnace 1 using a composite injection device 28 to complete the replenishment of reducing agent and heat in the furnace.

[0028] The present invention aims to optimize the problem shown in FIG1: In order to solve the problem that when the gas heating furnace heats the injected coke oven gas, the SiO2 in the refractory bricks in the high temperature zone of the dome of the hydrogen-rich carbon circulating oxygen blast furnace (HyCROF) gas heating furnace reacts with the H2 in the coke oven gas, which will cause weight loss and strength attenuation in long-term use, greatly affecting the stability and safety of the silicon bricks in the high temperature zone of the dome. See FIG2: After the heating is completed, the gas heating furnace 11 with a certain heat load, at the initial stage of heating of the cold decarbonized gas entering the heating furnace through the gas heating furnace 11, the temperature of the hot decarbonized gas will be much higher than the injection temperature, such as 1200°C. In order to maintain the stability of the injected gas temperature, the temperature fluctuation is ±5-10°C. In order to increase the reducing components (CO and H2) in the injected gas, the CH4 with a volume fraction of 22-24% in the coke oven gas can be decomposed or cracked into CO and H2, and it also has a volume fraction. The CO+H2 fraction is 55-60%, while maintaining the stability of the injected gas temperature with a temperature fluctuation of ±5-10°C. The optimized coke oven gas is mixed and added to the heated hot gas pipeline system to stabilize the temperature of the gas injected into the furnace at 1200°C. Using the flow and pressure output of the coke oven gas source 2, the first coke oven gas flow cut-off device 3 and the second coke oven gas flow cut-off device 8 are opened, and the coke oven gas flow regulating device 7 is adjusted to make the mixed flow rate of the coke oven gas flow detection 6 1000-14600Nm 3 / h, the coke oven gas pressure detection 5 is 50-100kPa higher than the pressure of the thermal decarbonization gas pressure detection 25, the coke oven gas temperature detection 4 is heated from the normal temperature of 25°C to the temperature of 1200°C measured by the hot mixed medium temperature detection 27, and the total flow rate into the furnace can be the sum of the thermal decarbonization gas flow detection 26 and the coke oven gas flow detection 6 as the operation basis.

[0029] If the mixed coke oven gas flow detection 6 of the coke oven gas flow regulating device 7 is adjusted to 14600Nm 3 / h (maximum amount), the temperature of the gas injected into the furnace is still higher than 1200℃, the first cold decarbonized gas flow cut-off device 12 and the second cold decarbonized gas flow cut-off device 17 are opened, and the 40℃ mixed cold decarbonized gas flow regulating device 16 can be adjusted to be introduced before entering the gas heating furnace, so that the temperature measured by the hot mixed medium temperature detection 27 is 1200℃, and the temperature of the gas injected into the furnace is stabilized at 1200℃. The total flow into the furnace is the sum of the hot decarbonized gas flow detection 26, the coke oven gas flow detection 6 and the cold decarbonized gas flow detection 15 as the operation basis.

[0030] The interlocking requirement for blending and adding is that the pressure of coke oven gas is 30-40kPa lower than the pressure of thermal decarbonization gas, and two flow cut-off devices are automatically closed to cut off the blending and adding. The safety device is to inject N2 between the flow cut-off devices while cutting off the coke oven gas source, specifically including 21-N2 gas source device; 22-N2 first cut-off device; 23-N2 second cut-off device.

[0031] The raw materials and coke for the hydrogen-rich carbon cycle oxygen blast furnace of the present invention are weighed by a dosing device 29 to calculate the batch iron content, theoretical coke ratio, and slag basicity. The raw materials are composed of 40-55% basic ore, 40-50% acidic ore, and 5-10% natural lump ore by mass. The coke is 250-280 kg / tHM.

[0032] The raw fuels, alkaline ore, acidic ore, natural lump ore and coke, are added in layers from the furnace top adding device 29. The injection coal 32, decarbonized coal gas, coke oven gas and natural gas are injected into the furnace from the composite injection device at the bottom of the furnace. At the same time, the composite injection device also injects industrial oxygen provided by the oxygen source 31 into the furnace. The oxygen content is 90-99.9% of room temperature cold oxygen, and the oxygen amount is controlled at 160-230Nm 3 / tHM, the implementation of the method of charging and multi-media heating and blowing, causes physical and chemical reactions to occur in the furnace, and ultimately obtains qualified molten iron and by-product gas and slag, while reducing solid fuel consumption and greenhouse gas CO2 emissions.

Claims

1. A method for injecting decarbonized coal gas and coke oven gas into a hydrogen-rich carbon circulating oxygen blast furnace, characterized in that: The devices used in the method include a coke oven gas flow regulating device, a pressure detecting device, a flow detecting device, a temperature detecting device, a flow cut-off device, a gas heating furnace outlet temperature, pressure, and flow detecting device, a post-mixing temperature detecting device, and a safety device; The implementation steps are as follows: 1) The method is used to adjust the gas injection temperature and the composition of the injected gas during the use of a hydrogen-rich carbon circulating oxygen blast furnace. The hydrogen-rich carbon circulating oxygen blast furnace is a metallurgical equipment. The fuel structure of the charge includes solid fuel and gaseous fuel. The solid fuel includes coke and injected coal. The gaseous fuel includes decarbonized coal gas and coke oven gas. The decarbonized coal gas is decarbonized coal gas containing reducing CO and H2 produced by removing CO2 and H2S from the coal gas at the furnace top. The ore distribution structure of the charge adopts alkaline ore, acidic ore and / or natural lump ore. The amount of coke used in the solid fuel is 250-280kg / tHM, the amount of injected coal is 40-80kg / tHM, and the injection circulation amount of the decarbonized coal gas in the gaseous fuel is 450-750Nm 3 / tHM, the injection consumption of coke oven gas is 50-150Nm 3 / tHM; 2) The decarbonized coal gas described in this method is heated in a coal gas heating furnace and mixed with coke oven gas at the outlet of the coal gas heating furnace. The high-temperature mixed coal gas after the mixing and adding has a temperature of 1200°C and contains the following components by volume: CO: 55-60%, H2: 12-25%, N2: 3-5%, CO2: 0-3%, and CH4: 8-10%. The high-temperature mixed coal gas obtained by mixing the decarbonized coal gas with the coke oven gas in this step is injected into the furnace through a composite injection device, and the pressure of the decarbonized coal gas is controlled at 0.35-0.4 MPa. Specifically: A: The hot gas pipeline after the gas heating furnace is mixed with room temperature coke oven gas (COG) to solve the problem of coke oven gas directly entering the high temperature area of ​​the dome of the gas heating furnace. Coke oven gas and H2 react with SiO2 at high temperature. During the mixing process with room temperature coke oven gas, the decarbonized gas temperature is 40℃ and the average specific heat capacity is 1.371kJ / Nm 3 .℃, the coke oven gas temperature is 25℃, and the average specific heat capacity is 1.369kJ / Nm 3 .℃; mix with room temperature coke oven gas and decarbonized gas, when the injection temperature of the high temperature mixed gas reaches the injection temperature of 1200℃, the flow rate of decarbonized gas increases from 20000Nm 3 / h increased to 190000Nm 3 / h, the heat required to heat the temperature from 40℃ to 1200℃ increases from 30.3GJ to 288GJ; the coke oven gas flow rate increases from 1000Nm 3 / h increased to 14600Nm 3 / h, the heat required to heat the temperature from 25℃ to 1200℃ increases from 1.6GJ to 23.5GJ; the total heat of the mixed coke oven gas and decarbonized gas increases from 31.9GJ to 311.5GJ; in order to maintain the temperature of the mixed medium at 1200℃ after blending, the actual outlet temperature of the gas heater increases from 1261.7℃ to 1294.8℃; the top gas of the hydrogen-rich carbon circulating oxygen blast furnace passes through the dust removal and dehydration device, and is pressurized to 0.45-1.6MPa by a compressor, and then enters the decarbonization device to remove CO2, forming a gas medium containing reducing components CO and H2 with a volume fraction of 65-85%. After passing the pressure, temperature and flow detection, it enters the gas heater and is heated to above 1200℃, and then is injected into the lower hearth of the hydrogen-rich carbon circulating oxygen blast furnace using a composite blowing device; A1: To maintain the stability of the injected gas temperature, the temperature fluctuation is controlled within ±(5-10)°C. Before entering the gas heating furnace, 40°C mixed cold decarbonized gas is introduced and mixed into the heated hot gas pipeline system to keep the injection temperature at 1200°C. A2: To increase the content of reducing components CO and H2 in the injected gas, the CH4 (22-24% by volume) in the coke oven gas, which already contains 55-60% by volume of CO+H2, is decomposed or cracked into CO and H2. To maintain the stability of the injected gas temperature, the temperature fluctuation is controlled within ±(5-10)°C. The coke oven gas is blended and fed into the decarbonized hot gas pipeline system after heating in the gas heating furnace, so that the injection temperature is stabilized at 1200°C. The pressure of the coke oven gas needs to be 50-100 kPa higher than that of the hot decarbonized gas. A3: The flow rate of coke oven gas is fixed at 1000-14600Nm 3 / h, and at the same time, adjust the flow control device of the 40℃ mixed cold decarbonized coal gas introduced into the gas heating furnace to stabilize the temperature of the gas injected into the furnace at 1200℃; A4: Use the flow regulating device to adjust the mixing flow of coke oven gas to 1000-14600Nm 3 / h, when the mixing flow of coke oven gas is adjusted to 14600Nm 3 / h, if the temperature injected into the furnace is higher than 1200℃, the flow regulating device of the mixed cold decarbonized coal gas at 40℃ introduced before the gas heating furnace can be adjusted to stabilize the temperature injected into the furnace at 1200℃; A5: The pressure of coke oven gas needs to be 30-40 kPa lower than that of thermally decarbonized coal gas. Two flow cut-off devices are provided to automatically shut down and cut off blending and addition. The safety device is used to inject nitrogen between the flow cut-off devices when the natural gas and coke oven gas sources are cut off. 3) The raw materials and coke of the hydrogen-rich carbon cycle oxygen blast furnace are weighed through a dosing device, and the batch iron content of the raw fuel, the theoretical coke ratio and the slag basicity are calculated. The raw materials, measured by the mass fraction of the ore, include 40-55% alkaline ore, 40-50% acidic ore, 5-10% natural lump ore, and 250-280 kg / tHM of coke. The raw materials, alkaline ore, acidic ore, natural lump ore and coke, are added in layers from the dosing device at the top of the furnace. Pulverized coal, decarbonized coal gas and coke oven gas are injected into the furnace through the composite injection device at the bottom of the furnace. At the same time, the composite injection device also injects industrial oxygen into the furnace. The industrial oxygen is room temperature cold oxygen with an oxygen content of 90-99.9%. The amount of oxygen injected is controlled at 160-230 Nm 3 / tHM, and then the final products, namely molten iron, by-product gas and slag, can be obtained through a hydrogen-rich carbon circulating oxygen blast furnace.

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