Method for adjusting hydrogen-rich carbon cycle oxygen blast furnace solid fuel ratio

Abstract

The invention provides a method for adjusting the solid fuel ratio of a hydrogen-rich carbon cycle oxygen blast furnace. The method comprises the following steps: step 1, calculating the variation of energy input of the hydrogen-rich carbon cycle oxygen blast furnace caused by cycle gas change; 2, effective energy input of the solid fuel per unit mass in the hydrogen-rich carbon circulation oxygen blast furnace is calculated; and 3, calculating the adjustment amount of the hydrogen-carbon-rich circulating oxygen blast furnace solid fuel ratio according to the results of the previous two steps.

Description

Technical Field

[0001] The present invention relates to a method for adjusting the solid fuel ratio of a hydrogen-rich carbon circulating oxygen blast furnace, and in particular to a method for accurately adjusting the solid fuel ratio according to the amount of circulating gas to maintain a stable furnace temperature when the amount of circulating gas in the hydrogen-rich carbon circulating oxygen blast furnace changes, and belongs to the field of low-carbon ironmaking. Background Art

[0002] With the increasing global warming and extreme weather events, addressing climate change and reducing greenhouse gas CO2 emissions have become severe challenges faced by all mankind. The steel industry is the backbone of national economic development, one of the key carbon emission industries in the industrial field, and one of the important areas for achieving carbon peak and carbon neutrality goals. Carbon peak and carbon neutrality in the steel industry is a complex system engineering. The steel industry mainly uses blast furnace + converter smelting long process technology, with coke and coal as the main fuels.

[0003] Blast furnaces are extremely efficient reactors that can provide the cleanest raw materials for steelmaking. It is unscientific for iron and steel metallurgy to completely abandon the blast furnace process route. The reason why blast furnaces have high carbon emissions is that they need large pieces of coke made from coal as a skeleton, reducing agent and heat source to ensure the efficient process of smelting iron ore into metallic iron. With the continuous development of blast furnace technology, the use of traditional ironmaking operation technologies such as fine materials, high wind temperature, oxygen-enriched coal injection, and reasonable material distribution to reduce carbon consumption and carbon emissions has approached the limit of conventional blast furnace operation. Although there is still a large part of CO in the blast furnace top gas, due to the limitation of chemical reaction equilibrium, excess CO needs to be maintained in the reduction gas, which limits the further improvement of carbon utilization in conventional blast furnaces. In the current process, the concentration of these CO in the gas is too low and can only be used for combustion and heat release, but not for reduction. In the era of fossil fuels, this process is the best process, and the CO in the gas has become a valuable resource and should play a more important role. At the same time, using hydrogen to replace carbon as a reducing agent and fuel in the iron-making process to the maximum extent can further reduce CO2 emissions and fundamentally achieve low-carbon smelting in blast furnaces.

[0004] The hydrogen-rich carbon cycle oxygen blast furnace technology can effectively solve this problem. The key is the full oxygen and coal gas quality improvement cycle. After the blast furnace achieves full oxygen blasting, a large amount of nitrogen is prevented from entering the blast furnace top gas, which is conducive to the separation of CO. The separated high-concentration CO coal gas is sent to the tuyere and the furnace body for reducing iron ore, and the carbon cycle is used to achieve the full utilization of carbon chemical energy. At the same time, the coal gas cycle also allows the hydrogen in the coal gas to circulate in the blast furnace, solving the problem of the decline in hydrogen utilization after the blast furnace uses a large amount of hydrogen-rich substances, and providing a prerequisite for the large-scale use of hydrogen-rich substances in the blast furnace, thereby reducing the consumption of fossil energy in the blast furnace process.

[0005] It can be seen that the hydrogen-rich carbon circulating oxygen blast furnace is very different from the traditional blast furnace in terms of process principles and processes, and the fuel structure has undergone fundamental changes. The biggest difference from the traditional blast furnace in terms of energy balance is that the high-temperature coal gas sprayed from the tuyere is an important component of the blast furnace heat source input. However, the amount of circulating coal gas is affected by many factors such as the operation in the furnace and the decarbonization process outside the furnace, and will change greatly with the fluctuation of production. In the existing theory and operation system, there is currently no method for adjusting the solid fuel ratio when adjusting the circulating coal gas amount of the hydrogen-rich carbon circulating oxygen blast furnace. In order to accurately control the adjustment amount of the solid fuel ratio and avoid production fluctuations caused by furnace heat or furnace cooling, the present invention proposes a method for adjusting the solid fuel ratio according to the circulating coal gas amount. According to the influence of the adjustment amount of the circulating coal gas on the heat balance in the furnace, the adjustment formula of the solid fuel ratio is calculated, thereby realizing the timely and accurate conversion of the circulating coal gas amount and the solid fuel ratio of the hydrogen-rich carbon circulating oxygen blast furnace under the premise of maintaining the furnace temperature stable. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a method for accurately adjusting the solid fuel ratio to maintain a stable furnace temperature when the amount of circulating gas in a hydrogen-rich carbon circulating oxygen blast furnace changes. During the calculation process, it is considered that the energy input to the blast furnace will change when the amount of circulating gas in the hydrogen-rich carbon circulating oxygen blast furnace changes, and the different utilization rates of the circulating gas are taken into account to obtain the energy input data of carbon and hydrogen elements in the blast furnace per ton of iron solid fuel and circulating gas, and then the adjustment amount of the solid fuel is calculated according to the change in the amount of circulating gas, ultimately achieving the purpose of accurately adjusting the solid fuel ratio to maintain a stable furnace temperature.

[0007] The energy-related changes in the circulating gas of the hydrogen-rich carbon circulating oxygen blast furnace are mainly:

[0008] 1) Capacity;

[0009] 2) CO content;

[0010] 3) H2 content;

[0011] 4) CH4 content.

[0012] The energy-related changes in the solid fuel of the hydrogen-rich carbon cycle oxygen blast furnace are mainly:

[0013] 1) Calorific value of solid fuel;

[0014] 2) Utilization rate of C and H in solid fuel.

[0015] The method for adjusting the solid fuel ratio of a hydrogen-rich carbon circulating oxygen blast furnace proposed by the present invention is divided into three steps:

[0016] The first step is to calculate the change in energy input of the hydrogen-rich carbon circulating oxygen blast furnace caused by the change in circulating coal gas. The second step is to calculate the effective energy input per unit mass of solid fuel in the hydrogen-rich carbon circulating oxygen blast furnace. The third step is to calculate the adjustment amount of the solid fuel ratio of the hydrogen-rich carbon circulating oxygen blast furnace based on the results of the first two steps.

[0017] in,

[0018] The first step is to calculate the change in energy input of the hydrogen-rich carbon circulating oxygen blast furnace caused by the change in circulating coal gas as follows:

[0019] (1) Physical heat carried by circulating gas:

[0020] The circulating gas needs to be heated to a high temperature before being injected into the hydrogen-rich carbon circulating oxygen blast furnace, and is a high-temperature gas. However, it is discharged from the furnace top after a series of physical and chemical reactions with the charge in the furnace. Therefore, from the perspective of the input and output of the entire process, the physical heat carried by the circulating gas is related to the inlet temperature and the furnace top temperature. In addition, the composition of the circulating gas does not change much during normal production, and its specific heat capacity does not change much either. Here, only the physical heat Q1 required for the change in the amount of gas per ton of iron is considered, and the calculation formula is as follows:

[0021] Q1=C 煤气 ·(T 顶温 -T 煤气 )·ΔV·ρ 煤气

[0022] Among them, C 煤气 is the average specific heat capacity of the circulating gas, kJ / (kg·K);

[0023] T 顶温 is the furnace top gas temperature, °C;

[0024] T 煤气 is the initial temperature of the gas, °C;

[0025] ΔV is the change of circulating gas per ton of iron, with an increase being a negative value and a decrease being a positive value, Nm 3 ;

[0026] ρ 煤气 is the average density of circulating gas, kg / Nm 3 ;

[0027] (2) Heat generated by the chemical reaction of CO in the furnace: Affected by the utilization rate of CO in the furnace, only a part of the CO in the circulating gas reacts to generate CO2 in the furnace, and the other part is still discharged from the top of the furnace in the form of CO. Therefore, the calculation formula for the heat Q2 generated by the chemical reaction of CO in the furnace is as follows:

[0028]

[0029] Among them, α CO is the CO content in coal gas, %;

[0030] η CO is the utilization rate of CO in the furnace, %;

[0031] ΔH CO is the reaction enthalpy of 1 mol CO to generate CO2, 283 kJ / mol;

[0032] (3) Heat generated by the chemical reaction of H2 in the furnace: H2 will not react completely in the furnace. The amount of reaction is affected by the hydrogen utilization rate. The unreacted H2 is still discharged from the top of the furnace in the form of H2. Therefore, the heat Q3 generated by the chemical reaction of H2 in the furnace is calculated as follows:

[0033] in, is the H2 content in coal gas, %;

[0034] is the utilization rate of H2 in the furnace, %;

[0035] is the reaction enthalpy of 1 mol H2 to generate H2O, 242 kJ / mol;

[0036] (4) Heat generated by the chemical reaction of CH4 in the furnace: The hydrogen-rich carbon cycle oxygen blast furnace mainly comes from coke oven gas, which contains CH4. Therefore, the effect of CH4 on the furnace temperature needs to be considered. CH4 is first cracked and oxidized into C and H2 in the cyclotron zone, and C is then 100% oxidized to CO. The generated CO and H2 will further undergo chemical reactions in the furnace, and their impact on the heat in the furnace will be the same as the heat calculation in (2) and (3). Therefore, the heat Q4 generated by the chemical reaction of CH4 in the furnace is calculated as follows:

[0037]

[0038] in, is the content of CH4 in coal gas, %;

[0039] is the utilization rate of H2 in the furnace, %;

[0040] is the reaction enthalpy of 1 mol CH4 to generate H2 and C, -75 kJ / mol;

[0041] ΔH C is the reaction enthalpy of 1 mol C to CO, 118 kJ / mol;

[0042] Combining the calculation results of (1)(2)(3)(4), we can get the change in energy input Q of the hydrogen-rich carbon circulating oxygen blast furnace caused by the change in circulating coal gas: 煤气 :

[0043]

[0044] The second step is to calculate the effective energy input per unit mass of solid fuel in the hydrogen-rich carbon cycle oxygen blast furnace as follows:

[0045] The solid fuels of the hydrogen-rich carbon circulating blast furnace are coke and pulverized coal. The time for coke to affect the furnace temperature lags behind a smelting cycle (4 to 6 hours), and the time for pulverized coal to affect the furnace temperature is close to that of the circulating coal gas. Therefore, when the amount of circulating coal gas changes, if the coke ratio is adjusted to adapt to the heat balance in the furnace, it needs to be advanced by one smelting cycle. If the coal ratio is adjusted to adapt to the heat balance in the furnace, it can be directly replaced.

[0046] (5) Physical heat carried by unit mass of solid fuel: The initial temperature of the solid fuel is related to the temperature of the conveying gas, which is generally lower than the furnace top temperature. The solid fuel undergoes a series of physical and chemical changes in the furnace, and the C and H elements are eventually discharged in the form of furnace top gas. Therefore, from the perspective of the input and output of the entire process, the physical heat carried by the circulating gas is related to the furnace inlet temperature and the furnace top temperature. The required physical heat Q5 calculation formula is as follows:

[0047] Q5=C 燃料 ·1·(T 顶温 -T 燃料 )

[0048] Among them, C 燃料 is the specific heat capacity of solid fuel, kJ / (kg·K);

[0049] T 顶温 is the furnace top gas temperature, °C;

[0050] T 燃料 is the initial temperature of solid fuel, °C;

[0051] 1 represents the unit mass, kg;

[0052] (6) Heat released by complete combustion of unit mass of solid fuel: Generally speaking, the ratio of solid fuel is stable, and the heat released by complete combustion is related to its calorific value. Therefore, the calculation formula of heat released by complete combustion of unit mass of solid fuel Q6 is as follows:

[0053] Q6=q 燃料 1

[0054] Among them, q 燃料 is the calorific value of solid fuel, kJ / kg;

[0055] (7) Heat from incomplete reaction of C and H elements in solid fuel in the furnace: C element in solid fuel will generate CO in the furnace. Affected by the utilization rate of CO and H2, CO and H2 will not completely participate in the reaction. Therefore, the formula for calculating the heat Q7 from incomplete reaction of C and H elements in solid fuel in the furnace based on the utilization rate of CO and H2 is as follows:

[0056]

[0057] Among them, α C is the mass fraction of C in solid fuel, %;

[0058] α H is the mass fraction of H in solid fuel, %;

[0059] Combining the calculation results of (5)(6)(7), the change in effective energy input per unit mass of solid fuel in the hydrogen-rich carbon cycle oxygen blast furnace can be obtained as Q 燃料 :

[0060]

[0061] The third step is to calculate the adjustment amount of the solid fuel ratio of the hydrogen-rich carbon cycle oxygen blast furnace:

[0062] When the amount of circulating gas in a hydrogen-rich carbon circulating oxygen blast furnace changes, its impact on the heat in the furnace can be calculated in the first step, and the effective heat input into the furnace by unit mass of solid fuel can be calculated in the second step. The calculation results of these two steps can be used to obtain the amount of solid fuel that needs to be adjusted to offset the impact of the change in circulating gas on the heat balance of the blast furnace. The calculation formula is as follows:

[0063]

[0064] Among them, m 燃料 It indicates the adjustment amount of the solid fuel ratio of the hydrogen-rich carbon cycle oxygen blast furnace. A positive value represents an increase in solid fuel, and a negative value represents a decrease in solid fuel, kg.

[0065] Compared with the prior art, the method using the above technical solution has the following advantages and beneficial effects:

[0066] The hydrogen-rich carbon circulating oxygen blast furnace process is a new process. The circulating gas volume is affected by many factors such as the operation inside the furnace and the decarbonization process outside the furnace, and will change greatly with the fluctuation of production. There is no adjustment and conversion method for the circulating gas volume and the solid fuel ratio in the existing theoretical and operating system. The calculation formula for obtaining the relationship between the circulating gas adjustment volume and the solid fuel ratio adjustment volume based on the heat balance inside the furnace proposed in the present invention can effectively solve the problem that the hydrogen-rich carbon circulating oxygen blast furnace process cannot accurately control the influence of the circulating gas volume and the solid fuel ratio on the furnace heat, and can achieve the effect of accurately controlling the solid fuel ratio adjustment volume when the circulating gas volume changes, so that the circulating gas volume and the solid fuel ratio can be converted in time and accurately, avoiding production fluctuations caused by furnace heat or furnace cooling, and has a guiding effect on the stable smooth operation of the hydrogen-rich carbon circulating oxygen blast furnace process and low-carbon smelting. DETAILED DESCRIPTION

[0067] The specific embodiments of the present invention are described in further detail below.

[0068] Below is a 400m 3 The actual data of the hydrogen-rich carbon cycle oxygen blast furnace further describes the calculation method proposed in the present invention in detail.

[0069] When the injected gas decreases by 200Nm 3 / tFe, the coal ratio in the solid fuel ratio is used instead of the circulating gas, and the required data is sorted out according to the real-time data during blast furnace production as shown in Table 1 below.

[0070] Table 1:

[0071] <![CDATA[Circulating gas change amount, Nm 3 / t]]> CO content in coal gas, % <![CDATA[H2 content in gas, %]]> <![CDATA[CH4 content in gas, %]]> 200 58 19 8 Average specific heat capacity of gas, kJ / (kg·K) Average density of gas, kg / Nm3 CO utilization rate, % <![CDATA[H2 utilization rate, %]]> 1.281 1.08 48 45 Furnace top temperature, ℃ Gas temperature, °C Pulverized coal temperature, °C 150 800 20 Average specific heat capacity of pulverized coal, kJ / (kg·K) Calorific value of pulverized coal, kJ / kg C content in coal powder, % H content in coal powder, % 1.15 29306 78 3.1

[0072] The data in the table are brought into the present invention to calculate the corresponding adjustment amount of the solid fuel ratio when the gas volume of the hydrogen-rich carbon circulating oxygen blast furnace circulating gas changes,

[0073]

[0074] That is, when the injected gas is reduced by 200Nm 3 / tFe, the coal injection ratio should be increased to 77.1kg / tFe to maintain the furnace temperature stable in the hydrogen-rich carbon circulation oxygen blast furnace.

[0075] The method for adjusting the solid fuel ratio of a hydrogen-rich carbon circulating oxygen blast furnace provided by the present invention is to accurately adjust the solid fuel ratio to maintain a stable furnace temperature when the amount of circulating coal gas in the hydrogen-rich carbon circulating oxygen blast furnace changes. The hydrogen-rich carbon circulating oxygen blast furnace is a new low-carbon ironmaking process, which is very different from the traditional blast furnace in terms of fuel use. The circulating coal gas is an important aspect of its energy input. The present invention takes into account that the energy input to the blast furnace will change when the amount of circulating coal gas in the hydrogen-rich carbon circulating oxygen blast furnace changes, and takes into account the different utilization rates of the circulating coal gas, and calculates the energy input data of the solid fuel, the carbon element and the hydrogen element in the circulating coal gas in the blast furnace, and then calculates the adjustment amount of the solid fuel according to the change in the amount of circulating coal gas, and finally achieves the purpose of accurately adjusting the solid fuel ratio to maintain a stable furnace temperature.

Claims

1. A method for adjusting the solid fuel ratio of a hydrogen-rich carbon cycle oxygen blast furnace, characterized in that: The steps include: Step 1: Calculate the change in energy input of the hydrogen-rich carbon circulating oxygen blast furnace caused by the change in circulating coal gas; Step 2: Calculate the effective energy input per unit mass of solid fuel in the hydrogen-rich carbon cycle oxygen blast furnace; Step 3: Calculate the adjustment amount of the solid fuel ratio of the hydrogen-rich carbon cycle oxygen blast furnace based on the results of the first two steps.

2. The method for adjusting the solid fuel ratio of a hydrogen-rich carbon cycle oxygen blast furnace according to claim 1, characterized in that: Step one includes: (1) Calculation of physical heat carried by circulating gas: Among them, the physical heat Q1 required for the change in the amount of coal gas per ton of iron is calculated using the following formula: Q1=C 煤气 ·(T 顶温 -T 煤气 )·ΔV·ρ 煤气 In the formula, C 煤气 is the average specific heat capacity of the circulating gas, kJ / (kg·K); T 顶温 is the furnace top gas temperature, °C; T 煤气 is the initial temperature of the gas, °C; ΔV is the change of circulating gas per ton of iron, with an increase being a negative value and a decrease being a positive value, Nm 3 ; ρ 煤气 is the average density of circulating gas, kg / Nm 3 ; (2) Calculation of heat Q2 generated by the chemical reaction of CO in the furnace: The following calculation formula is used: In the formula, α CO is the CO content in coal gas, %; η CO is the utilization rate of CO in the furnace, %; ΔH CO is the reaction enthalpy of 1 mol CO to generate CO2, 283 kJ / mol; (3) Calculation of the heat Q3 generated by the chemical reaction of H2 in the furnace: The following calculation formula is used: in, is the H2 content in coal gas, %; is the utilization rate of H2 in the furnace, %; The reaction enthalpy of 1 mol H2 to generate H2O is 242 kJ / mol; (4) Calculation of heat Q4 generated by the chemical reaction of CH4 in the furnace: The following calculation formula is used: In the formula, is the content of CH4 in coal gas, %; is the utilization rate of H2 in the furnace, %; is the reaction enthalpy of 1 mol CH4 to generate H2 and C, -75 kJ / mol; ΔH C is the reaction enthalpy of 1 mol C to CO, 118 kJ / mol; (5) Combining (1)-(4), we can obtain the change in energy input of hydrogen-rich carbon circulating oxygen blast furnace caused by the change in circulating coal gas, Q 煤气 :

3. The method for adjusting the solid fuel ratio of a hydrogen-rich carbon cycle oxygen blast furnace according to claim 1, characterized in that: In step 2, when the solid fuel is coke, the time of its effect on the furnace temperature lags behind one smelting cycle; when the solid fuel is coal powder, the time of its effect on the furnace temperature is close to that of the circulating coal gas.

4. The method for adjusting the solid fuel ratio of a hydrogen-rich carbon cycle oxygen blast furnace according to claim 1, 2 or 3, characterized in that: Step 2 includes: (1) Calculation of physical heat Q5 carried by unit mass of solid fuel: The following calculation formula is used: Q5=C 燃料 ·1·(T 顶温 -T 燃料 ) In the formula, C 燃料 is the specific heat capacity of solid fuel, kJ / (kg·K); T 顶温 is the furnace top gas temperature, °C; T 燃料 is the initial temperature of solid fuel, °C; 1 represents the unit mass, kg; (2) Calculation of the heat released by complete combustion of unit mass of solid fuel Q6: The following calculation formula is used: Q6=q 燃料 ·1 In the formula, q 燃料 is the calorific value of solid fuel, kJ / kg; (3) Calculation of heat Q7 of incomplete reaction of C and H elements in solid fuel in the furnace: The following calculation formula is used: In the formula, α C is the mass fraction of C in solid fuel, %; α H is the mass fraction of H in solid fuel, %; (4) Combining (1)-(3), we can obtain the change in effective energy input per unit mass of solid fuel in the hydrogen-rich carbon cycle oxygen blast furnace: 燃料 :

5. The method for adjusting the solid fuel ratio of a hydrogen-rich carbon cycle oxygen blast furnace according to claim 4, characterized in that: In step 3, the adjustment amount m of the solid fuel ratio of the hydrogen-rich carbon cycle oxygen blast furnace is 燃料 The following calculation formula is used:

6. The method for adjusting the solid fuel ratio of a hydrogen-rich carbon cycle oxygen blast furnace according to claim 4, characterized in that: m 燃料 A positive value indicates an increase in solid fuel, m 燃料 Negative values ​​represent a reduction in solid fuel.

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