Online calculation method for direct reduction degree of blast furnace

Abstract

The invention discloses an on-line calculation method for the direct reduction degree and a use method for judging the furnace condition of a blast furnace. According to the source and the destination of the carbon, the input of the carbon is composed of coke fixed carbon and pulverized coal fixed carbon, the output of the carbon is composed of pig iron carburization and carbon carried out by furnace top gas, the carbon carried out by the furnace top gas is composed of convolution area gasification carbon and direct reduction consumed carbon, and the direct reduction consumed carbon is composed of alloy element direct reduction consumed carbon and iron oxide reduction consumed carbon. And calculating the carbon consumption of the direct reduction of the iron oxide so as to obtain the direct reduction degree. Whether the furnace condition is cool or not is judged according to the direct reduction degree, and an early warning signal indicating that the furnace condition of the blast furnace is cool is timely and accurately provided.

Description

Technical Field

[0001] The present invention relates to the technical fields of ironmaking and energy, and particularly provides a calculation method specifically for real-time calculation of the direct reduction degree of an on-site blast furnace. Background Art

[0002] In modern steel production, blast furnace ironmaking is a core link, and its efficiency and energy consumption directly affect the cost and environmental impact of the entire production process. During the process of blast furnace ironmaking, usually the thermal state regulation of the blast furnace is based on the temperature of molten iron and silicon content, but generally adjustments are made only when the tapping temperature is lower or higher than the acceptable range for two times. This is a slow reaction regulation process and cannot timely judge whether the furnace condition is getting cooler. It may lead to an increase in direct reduction and heat consumption. In order to maintain a fixed operating temperature and thermal regime, additional coke must be input. This not only increases the production cost, but also causes the furnace condition to become cooler, which has an adverse impact on the overall production efficiency. At the same time, the iron production rate is increased, the demand for direct reduction and energy consumption are further increased, and then the temperature in the furnace continues to decrease, forming a negative feedback loop, exacerbating the phenomenon of the furnace condition getting cooler. In severe cases, it may lead to adhesion or accumulation of materials in the furnace, causing tuyere blockage, hearth accumulation, blast furnace shutdown for maintenance, prolonging the non-production time, and damaging refractory materials and other key components.

[0003] The direct reduction degree is an important indicator for judging whether the furnace condition is getting cooler. Therefore, those skilled in the art are committed to developing an online calculation method for the direct reduction degree of the blast furnace, so as to timely provide an early warning signal for the furnace condition getting cooler in the blast furnace, make adjustments, and ensure the smooth operation of the blast furnace. Summary of the Invention

[0004] To achieve the above object, the present invention provides an online calculation method for the direct reduction degree of a blast furnace, wherein the direct reduction degree is calculated according to the following formula by the carbon consumption for direct reduction of iron oxides:

[0005]

[0006] In the formula, r d is the direct reduction degree, C dFe is the carbon consumption for direct reduction of iron oxides, with the unit of t / hr; 12.011 is the molar mass of carbon, with the unit of g / mol; 55.845 is the molar mass of iron, with the unit of g / mol; Q Fe is the hourly output of pig iron, with the unit of t / hr; [Fe] l is the proportion of Fe component in pig iron; among them, Q Fe , [Fe] l are data obtained by on-line measurement in an industrial blast furnace;

[0007] The carbon consumption C for direct reduction of iron oxides dFeAccording to the carbon input and output balance in the blast furnace ironmaking process, it is calculated using the following formula:

[0008]

[0009] In the formula, C 焦炭 is the fixed carbon content of coke, in t / hr, and C 煤粉 is the fixed carbon content of pulverized coal, in t / hr; C l is the carbon content in pig iron, in t / hr; C(V gas ) is the carbon carried out by the top gas of the blast furnace, in t / hr; C da is the carbon consumption for the reduction of alloying elements, in t / hr; is the carbon content in the bosh gas of the blast furnace, in t / hr; among which C 焦炭 , C 煤粉 , C l are the data obtained by on-line measurement in an industrial blast furnace;

[0010] Since the gasified carbon amount in the raceway is equal to the carbon content in the bosh gas of the blast furnace, and the carbon content in the bosh gas is all composed of CO, it is calculated according to the following formula

[0011]

[0012] In the formula, is the volume of CO in the bosh of the blast furnace, in m 3 ; C b is the carbon amount burned at the tuyere, in t / hr; 22.4 is the volume occupied by each mole of gas under standard conditions, in l / mol; 1.25 is the density of CO, in kg / m 3 ; 0.4288 is the mass fraction of element C in CO;

[0013] When calculating C(V gas ), first, based on the nitrogen balance, the top gas volume of the blast furnace is estimated using the following formula:

[0014]

[0015] In the formula, is the mass flow rate of pulverized coal injected per hour, in t / hr; is the mass percentage of nitrogen element in the pulverized coal, 28.014 is the molar mass of N 2 , in g / mol; V b is the blast volume per hour, in m 3 / hr; V b (N 2 %) is the proportion of N 2 in the blast; V gasVgas is the hourly top gas volume, with the unit of m 3 / hr; V gas (N 2 %) is the proportion of N 2 in the top gas volume; where V b 、V b (N 2 %), V gas (N 2 %) are the data obtained by on-line measurement in an industrial blast furnace; then the carbon amount C(V gas ) carried out by the top gas is calculated according to the following formula:

[0016] C(CO) = Vgas * Vgas(CO%) * 1.25 * 0.4288;

[0017] C(CO 2 ) = Vgas * Vgas(CO 2 %) * 1.99 * 0.2729;

[0018] C(V gas ) = C(CO) + C(CO 2 );

[0019] In the formula, C(CO), C(CO 2 ) respectively represent the carbon content of CO and CO 2 gases in the top gas, Vgas(CO%), Vgas(CO 2 %) respectively represent the proportion of CO and CO 2 in the top gas, 1.99 is the density of CO 2 , with the unit of kg / m 3 ; 0.2729 is the elemental mass fraction of C in CO 2 ; where Vgas(CO%), Vgas(CO 2 %) are the data obtained by on-line measurement in an industrial blast furnace.

[0020] The present invention discloses an on-line calculation method for the direct reduction degree and a usage method for judging the blast furnace condition. According to the source and destination of carbon, the carbon input consists of the fixed carbon of coke and the fixed carbon of pulverized coal, the carbon output consists of the carburization of pig iron and the carbon carried out by the top gas, the carbon carried out by the top gas consists of the gasified carbon in the raceway and the carbon consumed by direct reduction, the carbon consumed by direct reduction consists of the carbon consumed by the direct reduction of alloy elements and the carbon consumed by the reduction of iron oxides, calculate the carbon consumption of the direct reduction of iron oxides, so as to obtain the direct reduction degree. Judge whether the furnace condition is getting cooler according to the direct reduction degree, and provide an early warning signal for the cooler furnace condition of the blast furnace in a timely and accurate manner.

[0021] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, features and effects of the present invention. Description of the Drawings

[0022] Figure 1 is the process flow chart of calculating the direct reduction degree of the present invention in a preferred embodiment of the present invention;

[0023] Figure 2 is the process flow chart of blast furnace gas calculation in a preferred embodiment of the present invention. Detailed Embodiments

[0024] The following introduces multiple preferred embodiments of the present invention with reference to the accompanying drawings of the specification to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms of embodiments, and the protection scope of the present invention is not limited to the embodiments mentioned in the text.

[0025] In the drawings, components with the same structure are denoted by the same reference numerals, and components with similar structures or functions are denoted by similar reference numerals. The size and thickness of each component shown in the drawings are arbitrarily shown, and the present invention does not limit the size and thickness of each component. To make the illustration clearer, the thickness of some parts in the drawings is appropriately exaggerated.

[0026] See Figure 1 and Figure 2 The technical solution adopted by the present invention is to calculate the hourly calculated reduction degree based on the input and output of the hourly pig iron production and carbon amount in the blast furnace.

[0027] All the data mentioned here are measured in tons per hour (t / hr). The substances measured by the present invention include: coke amount, pulverized coal injection amount, pig iron production, proportion of fixed carbon component in coke, proportion of fixed carbon component in pulverized coal, proportion of pig iron component content, proportion of top gas component content. The measuring means include: weighing hopper, industrial analysis instrument, top gas on-line gas analysis system.

[0028] The proportion of fixed carbon in coke, fixed carbon in pulverized coal, carburization of pig iron, elements such as Si, Mn, P, S in pig iron components are determined according to industrial component analysis, and the carbon carried out by the top gas is determined according to the measurement results of the top gas on-line gas analysis system.

[0029] The belly gas refers to when hot air, coal, hydrogen and humidity are blown into the blast furnace together through the tuyere, the components react in the tuyere raceway to generate CO, H 2 、N 2 , the gas rises in the furnace to 1200 °C, and a direct reduction reaction occurs, generating additional CO and H 2. In the bosh section, indirect reduction is very limited, and any generated CO 2 and H 2 O will instantly react with coke and generate CO and H 2 again. The top gas refers to the gas mixture discharged from the top of the blast furnace. The gas mainly includes CO, H 2 , N 2 , CO 2 , H 2 O and a small amount of CH 4 . The measured value of the top gas online gas analysis system is dry top gas and does not contain H 2 O.

[0030] The blast volume refers to the total volume of the air and oxygen-enriched mixture entering the blast furnace. The total volume not only involves the evaluation of standard air containing about 21% O 2 , 78% N 2 , but also includes the additional oxygen-enriched gas added, that is, the volume of the gas with an oxygen concentration higher than that of ordinary air.

[0031] The top gas volume is calculated based on the nitrogen balance. During the blast furnace ironmaking process, nitrogen mainly plays a role in transferring heat, and due to its stable chemical properties, no significant chemical reactions or consumption occur during this process. Therefore, the total amount of nitrogen remains basically constant. The following formula is used to estimate the top gas volume.

[0032]

[0033] In the formula, is the mass flow rate of pulverized coal injected per hour (t / hr), is the mass percentage of nitrogen element in the pulverized coal, 28.014 is the molar mass of N 2 , V b is the blast volume per hour (m 3 / hr), V b (N 2 %) is the proportion of N 2 in the blast, V gas is the top gas volume per hour (m 3 / hr), V gas (N 2 %) is the proportion of N 2 in the top gas volume.

[0034] The carbon carried out by the top gas mainly exists in the form of CO and CO 2 . The carbon amount C(V gas ) carried out by the top gas is calculated according to the following formula.

[0035] C(CO) = Vgas * Vgas(CO%) * 1.25 * 0.4288

[0036] C(CO 2 ) = Vgas * Vgas(CO 2 %) * 1.99 * 0.2729

[0037] C(V gas ) = C(CO) + C(CO 2 )

[0038] In the formula, C(CO), C(CO 2 ) respectively represent the carbon content of CO and CO 2 in the top gas, Vgas(CO%), Vgas(CO 2 %) respectively represent the proportion of CO and CO 2 in the top gas, 1.25 is the density of CO (kg / m 3 ), 1.99 is the density of CO 2 (kg / m 3 ), 0.4288 is the elemental mass fraction of C in CO, and 0.2729 is the elemental mass fraction of C in CO 2 .

[0039] The carbon gasified in the raceway is equal to the carbon content of the blast furnace bosh gas. The carbon content of the bosh gas is all composed of CO. The carbon gasified in the bosh gas, that is, the carbon gasified in the raceway, is calculated according to the following formula.

[0040]

[0041] In the formula, is the volume of CO in the blast furnace bosh (m 3 ), C b is the carbon amount burned in front of the tuyere (t / hr), 22.4 is the volume occupied by each mole of gas under standard conditions (l / mol), and 12.011 is the molar mass of carbon (g / mol).

[0042] The carbon burned at the tuyere refers to the amount of carbon that enters the blast furnace and burns at the tuyere. The carbon burned at the tuyere is calculated using the following formula.

[0043] C b = (C 焦炭 + C 煤粉 ) - (C l + C da + C dFe )

[0044] In the formula, C 焦炭 is the fixed carbon amount of coke (t / hr), C 煤粉 is the fixed carbon amount of pulverized coal (t / hr), Cl is the carbon content in pig iron (t / hr), C da is the carbon consumption for reducing alloying elements (t / hr), C dFe is the carbon consumption for direct reduction of iron oxides (t / hr).

[0045] The degree of direct reduction is calculated from the carbon consumption for direct reduction of iron oxides..

[0046]

[0047] In the formula, r d is the degree of direct reduction, 55.845 is the molar mass of iron (g / mol), Q Fe is the hourly output of pig iron (t / hr), [Fe] l is the proportion of Fe component in pig iron.

[0048] The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and variations based on the concept of the present invention without creative efforts. Therefore, all technical solutions that can be obtained by those skilled in the art in the technical field according to the concept of the present invention through logical analysis, reasoning or limited experiments on the basis of the prior art should be within the protection scope determined by the claims.

Claims

1. An online calculation method for blast furnace direct reduction degree, characterized in that: The direct reduction degree is calculated by the carbon consumption of direct reduction of iron oxides according to the following formula: In the formula, r d is the direct reduction degree, C dFe is the carbon consumption for direct reduction of iron oxides, in t / hr; 12.011 is the molar mass of carbon, in g / mol; 55.845 is the molar mass of iron, in g / mol; Q Fe is the output of pig iron per hour, in t / hr; [Fe] l is the percentage of Fe in pig iron; Q Fe , [Fe] l It is the data obtained by online measurement in industrial blast furnace; Carbon consumption of direct reduction of iron oxides C dFe According to the carbon input and output balance in the blast furnace ironmaking process, the following formula is used for calculation: In the formula, C 焦炭 is the fixed carbon content of coke, in t / hr, C 煤粉 is the fixed carbon content of pulverized coal, in t / hr; C l is the carbon content in pig iron, in t / hr; C(V gas ) is the carbon carried out by the top gas, in t / hr; C da is the carbon consumption for alloy element reduction, in t / hr; is the carbon content of blast furnace bosh gas, in t / hr; C 焦炭 , C 煤粉 , C l It is the data obtained by online measurement in industrial blast furnace; Since the carbon content of gasification in the cyclone zone is equal to the carbon content of the blast furnace bosh gas, and the carbon content of the bosh gas is entirely composed of CO, it is calculated according to the following formula: In the formula, is the volume of CO in the blast furnace bosh, in m 3 ; C b is the amount of carbon burned at the tuyere, in t / hr; 22.4 is the volume occupied by each mole of gas under standard conditions, in l / mol; 1.25 is the density of CO, in kg / m 3 ; 0.4288 is the element mass fraction of C in CO; Calculate C(V gas ), firstly, based on the nitrogen balance, the furnace top gas volume is estimated using the following formula: In the formula, is the mass flow rate of pulverized coal injected per hour, in t / hr; is the mass percentage of nitrogen in coal powder, 28.014 is the molar mass of N2, in g / mol; V b is the blast air volume per hour, in m 3 / hr; V b (N2%) is the proportion of N2 in the blast; V gas is the amount of gas at the top of the furnace per hour, in m 3 / hr; V gas (N2%) is the proportion of N2 in the furnace top gas; V b 、V b (N2%), V gas (N2%) is the data obtained by online measurement in industrial blast furnaces; then the carbon content C(V gas ): C(CO)=Vgas*Vgas(CO%)*1.25*0·4288; C(CO2)=Vgas*Vgas(CO2%)*1.99*0.2729; C(V gas )=C(CO)+C(CO2); In the formula, C(CO) and C(CO2) represent the carbon content of CO and CO2 in the furnace top gas, respectively; Vgas(CO%) and Vgas(CO2%) represent the composition ratio of CO and CO2 in the furnace top gas, respectively; 1.99 is the density of CO2, in kg / m 3 ; 0.2729 is the element mass fraction of C in CO2; Vgas(CO%) and Vgas(CO2%) are data obtained by online measurement in industrial blast furnaces.

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