Blast furnace high volatile bitumite injection furnace temperature regulation method

Abstract

The present application provides a blast furnace high volatile bituminous coal injection furnace temperature regulation method, belongs to the field of blast furnace ironmaking calculation. The present application determines the blast furnace heat loss, theoretical combustion temperature and slag basicity of the reference period through full furnace energy quality balance calculation and regional energy quality balance calculation; then adjusts the volatile content of bituminous coal, maintains the blast furnace coke ratio unchanged, comprehensively adjusts the sinter proportion entering the furnace, coal ratio, oxygen enrichment rate to maintain the blast furnace heat loss, theoretical combustion temperature and slag basicity basically unchanged, and then indirectly regulates the blast volume, ore quantity, slag quantity, bosh coal gas quantity, H2 and CO utilization rate and other parameters, realizes the furnace temperature regulation, and ensures that the blast furnace can normally and stably produce after injecting high volatile bituminous coal.

Description

Technical Field

[0001] This invention relates to the field of pulverized coal injection technology in blast furnace ironmaking, and more particularly to a method for controlling the furnace temperature of blast furnace high-volatile bituminous coal injection. Background Technology

[0002] As an energy- and resource-intensive industry, the steel industry consumes approximately 150 million tons of pulverized coal annually, primarily anthracite, with bituminous coal, a low-rank coal, accounting for less than 40%. However, my country faces a shortage of anthracite resources, with recoverable reserves insufficient for more than 21 years, while low-rank coal reserves are abundant. Therefore, the rational and effective utilization of various low-rank coal resources, expanding the sources of fuel for ironmaking, and reducing fuel costs in the ironmaking process have become key breakthroughs for coal and steel enterprises seeking profits under the new normal of economic development.

[0003] From the perspective of blast furnace smelting technology, bituminous coal is more suitable for pulverized coal injection because it has good combustion performance, which is conducive to the combustion of pulverized coal in the blast furnace, thereby increasing the pulverized coal injection ratio. At the same time, because bituminous coal is widely distributed and relatively inexpensive, it can further reduce the cost of ironmaking fuel. Therefore, pulverized coal injection has become the direction of development for blast furnace ironmaking production. Currently, most advanced blast furnaces abroad and some domestic blast furnaces are gradually increasing the amount of bituminous coal injected.

[0004] However, when increasing the bituminous coal injection rate to 100% and using only high-volatile bituminous coal, changes in the volatile matter content of the coal, without effective control of process parameters, can lead to problems such as insufficient hearth heat and excessive fuel consumption, causing abnormal blast furnace conditions and affecting normal blast furnace production. How to control process parameters to ensure normal blast furnace production even after changes in bituminous coal volatile matter content is a pressing issue that needs to be addressed.

[0005] In view of this, it is necessary to design a method for controlling the furnace temperature of blast furnaces with high volatile matter bituminous coal injection, so as to effectively control the furnace temperature through specific parameter adjustment after the volatile matter content of bituminous coal changes, in order to solve the above problems. Summary of the Invention

[0006] To address the shortcomings of the existing technology, the present invention aims to provide a method for controlling the furnace temperature of blast furnaces injecting high-volatile bituminous coal. This method uses blast furnace heat loss, theoretical combustion temperature, and slag basicity as control targets. By maintaining a constant blast furnace coke ratio and comprehensively adjusting the sinter feed ratio, coal ratio, and oxygen enrichment rate, the blast furnace heat loss, theoretical combustion temperature, and slag basicity are kept essentially constant. This indirectly controls parameters such as blast volume, ore quantity, slag quantity, furnace gas quantity, and H2 and CO utilization rates to achieve furnace temperature control, ensuring normal and stable production after the injection of high-volatile bituminous coal into the blast furnace.

[0007] To achieve the above objectives, the present invention provides a method for temperature control in a blast furnace using high-volatile bituminous coal injection, comprising the following steps:

[0008] S1. Pre-set the blast furnace process parameters for the reference period, and determine the blast furnace heat loss, theoretical combustion temperature and slag basicity for the reference period through whole furnace energy and mass balance calculation and regional energy and mass balance calculation.

[0009] S2. Keep the blast furnace process parameters of the baseline period, only change the volatile matter content of the injected bituminous coal, and then obtain the blast furnace heat loss, theoretical combustion temperature and slag basicity corresponding to the changed bituminous coal volatile matter content through whole furnace energy quality balance calculation and regional energy quality balance calculation.

[0010] S3. Based on step S2, keep the coke ratio and volatile matter content of bituminous coal unchanged, adjust the sinter feed ratio, oxygen enrichment rate and coal ratio to make the calculated blast furnace heat loss, theoretical combustion temperature and slag basicity consistent with the corresponding parameter values ​​of the baseline period in step S1, obtain the actual process parameters corresponding to the changed bituminous coal volatile matter content, and complete the furnace temperature control.

[0011] As a further improvement of the present invention, in step S3, the adjustment method of the sinter feed ratio, oxygen enrichment rate and coal ratio is as follows: first, gradually increase or gradually decrease the sinter feed ratio to keep the slag basicity consistent with the value of the reference period; then, alternately adjust the coal ratio and oxygen enrichment rate to keep the blast furnace heat loss obtained after adjusting the coal ratio consistent with the value of the reference period, and the theoretical combustion temperature obtained after adjusting the oxygen enrichment rate consistent with the value of the reference period.

[0012] As a further improvement of the present invention, the overall furnace energy and mass balance calculation includes material balance and overall furnace heat balance.

[0013] As a further improvement of the present invention, the regional energy-mass balance calculation refers to the calculation of the theoretical combustion temperature in the air vent swirl zone.

[0014] As a further improvement of the present invention, the blast furnace heat loss is calculated according to the following formula:

[0015]

[0016] In the formula, η HL For blast furnace heat loss, %; Q Z Total heat expenditure; Q YF Q represents the total heat consumed in the decomposition of oxides. S Heat consumption for desulfurization; Q Fuel-F The heat consumed by the decomposition of injected fuel; Q slag Enthalpy carried away by slag; Q pig-iron The enthalpy carried away by molten iron; Q dust The heat carried away by the furnace dust; Q gas The heat carried away by the gas at the top of the furnace; Heat is consumed during the decomposition of water; This is the heat loss due to carbon melting.

[0017] As a further improvement of the present invention, the theoretical combustion temperature is calculated according to the following formula:

[0018]

[0019] In the formula, T f Q is the theoretical combustion temperature; ck The heat released by the combustion of coke; Q cm The heat released by the combustion of pulverized coal; H b Sensible heat introduced by the oxygen-enriched blower; H ck Sensible heat introduced by coke; H m Sensible heat introduced by pulverized coal; H gas The sensible heat introduced by the pulverized coal carrier gas; Q w-g The water-gas reaction is endothermic; Q decom The fuel decomposition absorbs heat; Q gas The carrier gas absorbs heat; V g The volume of gas in the furnace hearth; m a The ash content of coke and fuel burned in front of the tuyeres; m w C represents the amount of unburned fuel. pg The heat capacity of the gas in the furnace hearth; C a Specific heat capacity of ash; C w This is the specific heat capacity of unburned fuel.

[0020] As a further improvement of the present invention, the pulverized coal combustion rate corresponding to bituminous coal with different volatile matter content is obtained by a blast furnace pulverized coal injection simulation experimental device and used for the calculation of the heat release of pulverized coal combustion.

[0021] As a further improvement of the present invention, the slag alkalinity is calculated according to the following formula:

[0022]

[0023] In the formula, R is the binary basicity of the slag; The content of CaO in the slag, in kg / t; The content of SiO2 in the slag is expressed in kg / t.

[0024] As a further improvement of the present invention, in step S1, the volatile matter content of the bituminous coal in the reference period is 31%; in step S2, the volatile matter content of the modified bituminous coal is 33% to 37%.

[0025] As a further improvement of the present invention, in step S1, the blast furnace process parameters include the composition and proportion of sinter, pellets and lump ore used in blast furnace smelting, the composition, coke ratio, coal ratio, preset pig iron composition and blast parameters of coke and bituminous coal used in blast furnace smelting.

[0026] The beneficial effects of this invention are:

[0027] The blast furnace temperature control method provided by this invention, based on overall furnace energy and mass balance calculations and regional energy and mass balance calculations, uses blast furnace heat loss, theoretical combustion temperature, and slag basicity as direct control targets. Compared to methods that only control the theoretical combustion temperature, this method can more comprehensively and accurately reflect the actual furnace temperature, avoiding problems such as insufficient hearth heat and excessive fuel consumption, thus ensuring normal blast furnace production. Furthermore, after changing the volatile matter content of the bituminous coal, to facilitate more convenient and effective furnace temperature control, this invention maintains a constant blast furnace coke ratio, using blast furnace heat loss, theoretical combustion temperature, and slag basicity to maintain consistency with the baseline period as control targets. It adjusts the sinter feed ratio, coal ratio, and oxygen enrichment rate according to a set pattern. While controlling blast furnace heat loss, theoretical combustion temperature, and slag basicity, it can also indirectly control parameters such as blast volume, ore quantity, slag quantity, furnace gas quantity, H2 and CO utilization rates, achieving furnace temperature control to ensure normal and stable production after the injection of high-volatile bituminous coal into the blast furnace. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to specific embodiments.

[0029] Additionally, it should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0030] This invention provides a method for temperature control in a blast furnace using high-volatile bituminous coal injection, comprising the following steps:

[0031] S1. Pre-set the blast furnace process parameters for the reference period, and determine the blast furnace heat loss, theoretical combustion temperature and slag basicity for the reference period through whole furnace energy and mass balance calculation and regional energy and mass balance calculation.

[0032] S2. Keep the blast furnace process parameters of the baseline period, only change the volatile matter content of the injected bituminous coal, and then obtain the blast furnace heat loss, theoretical combustion temperature and slag basicity corresponding to the changed bituminous coal volatile matter content through whole furnace energy quality balance calculation and regional energy quality balance calculation.

[0033] S3. Based on step S2, keep the coke ratio and volatile matter content of bituminous coal unchanged, adjust the sinter feed ratio, oxygen enrichment rate and coal ratio to make the calculated blast furnace heat loss, theoretical combustion temperature and slag basicity consistent with the corresponding parameter values ​​of the baseline period in step S1, obtain the actual process parameters corresponding to the changed bituminous coal volatile matter content, and complete the furnace temperature control.

[0034] The blast furnace process parameters include the composition and proportion of sinter, pellets, and lump ore used in blast furnace smelting; the composition, coke ratio, coal ratio, preset pig iron composition, and blast parameters of coke and bituminous coal used in blast furnace smelting. Specifically, based on blast furnace smelting experience, the composition of sinter, pellets, and lump ore used in blast furnace production is analyzed; industrial and elemental analyses are performed on coke and bituminous coal used in blast furnace production; and the ash composition of coke and bituminous coal is determined. Combined with basic blast furnace production data, and based on the principle of energy and mass balance, overall furnace energy and mass balance calculations and regional energy and mass balance calculations are performed. Overall furnace energy and mass balance calculations include material balance and overall furnace heat balance; regional energy and mass balance calculations refer to the calculation of the theoretical combustion temperature in the tuyeres swirl zone.

[0035] Specifically, the heat loss of the blast furnace is calculated according to the following formula:

[0036]

[0037] In the formula, η HL For blast furnace heat loss, %; Q Z Total heat expenditure; Q YF Q represents the total heat consumed in the decomposition of oxides. S Heat consumption for desulfurization; Q Fuel-F The heat consumed by the decomposition of injected fuel; Q slag Enthalpy carried away by slag; Q pig-iron The enthalpy carried away by molten iron; Q dust The heat carried away by the furnace dust; Q gas The heat carried away by the gas at the top of the furnace; Heat is consumed during the decomposition of water; This is the heat loss due to carbon melting.

[0038] The theoretical combustion temperature is calculated using the following formula:

[0039]

[0040] In the formula, T f Q is the theoretical combustion temperature; ck The heat released by the combustion of coke; Q cm The heat released by the combustion of pulverized coal; H b Sensible heat introduced by the oxygen-enriched blower; H ck Sensible heat introduced by coke; H m Sensible heat introduced by pulverized coal; H gas The sensible heat introduced by the pulverized coal carrier gas; Q w-g The water-gas reaction is endothermic; Q decom The fuel decomposition absorbs heat; Q gas The carrier gas absorbs heat; V g The volume of gas in the furnace hearth; m aThe ash content of coke and fuel burned in front of the tuyeres; m w C represents the amount of unburned fuel. pg The heat capacity of the gas in the furnace hearth; C a Specific heat capacity of ash; C w This refers to the specific heat capacity of unburned fuel. It should be noted that when the injection rate of bituminous coal reaches 100%, the coal powder mentioned in this article refers to bituminous coal.

[0041] Among them, the heat released by pulverized coal combustion is Q cm The following formula is used for calculation:

[0042]

[0043] In the formula, q cm The heat released when one kg of carbon in pulverized coal burns to CO is taken as the same value as the heat of carbon combustion in coke, which is 4.18 × 2340 kJ·kg. -1 η represents the combustion rate of pulverized coal, in percentages; W M The hourly pulverized coal injection rate is expressed in kJ·h. -1 C M The carbon content (including fixed carbon) in pulverized coal, %; H2O M The moisture content of pulverized coal is %.

[0044] Preferably, the pulverized coal combustion rate η corresponding to bituminous coal with different volatile matter contents is obtained by detecting the pulverized coal injection simulation experiment device in a blast furnace. Compared with other calculation methods, this method can more accurately reflect the actual situation and is beneficial to improving the accuracy of the control method provided by the present invention. In one embodiment of the present invention, the pulverized coal injection simulation experiment device used is the experimental device provided in the patent with publication number CN201258335Y.

[0045] The alkalinity of the slag is calculated according to the following formula:

[0046]

[0047] In the formula, R is the binary basicity of the slag; The content of CaO in the slag, in kg / t; The content of SiO2 in the slag is expressed in kg / t.

[0048] It should be noted that the improvement of this invention over the prior art does not lie in how to calculate each parameter involved in the above formula, and the calculation methods for these parameters are well known in the art, so they will not be described in detail here. The improvement of this invention lies in addressing the problems of insufficient hearth heat and high fuel consumption caused by the different volatile matter content of bituminous coal during high-volatile matter coal injection. It proposes to use the blast furnace heat loss, theoretical combustion temperature, and slag basicity in the baseline period as direct control targets, and preferably maintains the blast furnace coke ratio unchanged, while controlling the blast furnace heat loss, theoretical combustion temperature, and slag basicity by regularly adjusting the sinter feed ratio, coal ratio, and oxygen enrichment rate. This conveniently and efficiently adjusts the blast furnace heat loss, theoretical combustion temperature, and slag basicity to be consistent with the baseline period. During this adjustment process, changes in the proportion of sintered ore fed into the furnace, the coal ratio, and the oxygen enrichment rate not only affect the calculation results of blast furnace heat loss, theoretical combustion temperature, and slag basicity, but also affect the calculation results of parameters such as blast volume, ore volume, slag volume, furnace gas volume, H2 and CO utilization rate. Based on the basic calculations, the corresponding parameters after adjustment can be obtained, ensuring normal and stable production after the blast furnace is injected with high volatile bituminous coal while effectively controlling the furnace temperature.

[0049] Specifically, based on the variation patterns obtained by the inventors, changes in the coal ratio and oxygen enrichment rate have virtually no impact on slag basicity, while the sinter feed ratio is positively correlated with slag basicity. Therefore, adjusting the sinter feed ratio can effectively regulate slag basicity. Changes in the coal ratio and oxygen enrichment rate, however, affect blast furnace heat loss and theoretical combustion temperature. Specifically, the coal ratio primarily affects blast furnace heat loss and also alters the theoretical combustion temperature; the coal ratio is positively correlated with heat loss and negatively correlated with theoretical combustion temperature. The oxygen enrichment rate primarily affects the theoretical combustion temperature and also alters heat loss; the oxygen enrichment rate is positively correlated with theoretical combustion temperature and negatively correlated with blast furnace heat loss. Based on this, when adjusting the sinter feed ratio, oxygen enrichment rate, and coal ratio:

[0050] First, gradually increase or decrease the proportion of sinter fed into the furnace to keep the slag basicity consistent with the value of the baseline period (if it is necessary to increase the slag basicity, gradually increase the proportion of sinter fed into the furnace; otherwise, gradually decrease the proportion of sinter fed into the furnace until the slag basicity reaches the value of the baseline period).

[0051] The coal ratio and oxygen enrichment rate are then alternately adjusted to ensure that the blast furnace heat loss obtained after adjusting the coal ratio remains consistent with the value of the baseline period, and the theoretical combustion temperature obtained after adjusting the oxygen enrichment rate remains consistent with the value of the baseline period. The specific method is as follows:

[0052] Gradually increase or decrease the coal ratio to keep the blast furnace heat loss consistent with the baseline period (if it is necessary to increase the blast furnace heat loss, gradually increase the coal ratio; otherwise, gradually decrease the coal ratio until the blast furnace heat loss reaches the baseline period value).

[0053] Gradually increase or decrease the oxygen enrichment ratio to keep the theoretical combustion temperature consistent with the value of the reference period (if it is necessary to increase the theoretical combustion temperature, gradually increase the oxygen enrichment ratio; otherwise, gradually decrease the oxygen enrichment ratio until the theoretical combustion temperature reaches the value of the reference period).

[0054] If the blast furnace heat loss is inconsistent with the baseline value after adjusting the oxygen enrichment rate, repeat the above steps, alternately adjusting the coal ratio and oxygen enrichment rate until the final blast furnace heat loss and theoretical combustion temperature are consistent with the baseline value.

[0055] It should be noted that the differences between the adjusted slag basicity, blast furnace heat loss, and theoretical combustion temperature and their corresponding values ​​in the baseline period are considered consistent as long as they are within the allowable error range. Preferably, the differences between the adjusted slag basicity and the baseline slag basicity are within 0.0005%, the differences between the adjusted blast furnace heat loss and the baseline blast furnace heat loss are within 0.005%, and the differences between the adjusted theoretical combustion temperature and the baseline theoretical combustion temperature are within 0.5℃. Since the coal ratio and oxygen enrichment rate have different effects on blast furnace heat loss and theoretical combustion temperature, alternatingly adjusting the coal ratio and oxygen enrichment rate in the above manner can ultimately reduce the differences between the corresponding values ​​of blast furnace heat loss and theoretical combustion temperature and their corresponding values ​​in the baseline period to within the allowable error range.

[0056] In some embodiments of the present invention, in step S1, the volatile matter content of the bituminous coal in the baseline period is 31%; in step S2, the volatile matter content of the bituminous coal can be gradually increased to 33% to 37%.

[0057] The method for controlling the temperature of blast furnace high-volatile bituminous coal injection provided by the present invention will be described below with reference to specific embodiments.

[0058] Example

[0059] This embodiment provides a method for temperature control in a blast furnace using high-volatile bituminous coal injection, including the following steps:

[0060] S1. Based on the pre-set blast furnace process parameters for the baseline period, determine the blast furnace heat loss, theoretical combustion temperature, and slag basicity corresponding to the baseline period when the bituminous coal with a total volatile matter content of 31% is injected, through whole-furnace energy and mass balance calculation and regional energy and mass balance calculation.

[0061] In this embodiment, the pre-set blast furnace process parameters include the composition and proportion of the sinter, pellets and lump ore used, the composition, coke ratio, coal ratio of the coke and bituminous coal used in blast furnace smelting, the preset pig iron composition and blast parameters, etc., as shown in Tables 1 to 5.

[0062] Table 1. Main chemical components of blast furnace feedstock and the proportion of various ores charged into the furnace (wt%,%)

[0063]

[0064] Table 2 Fuel composition / wt, %

[0065]

[0066] Table 3 Preset molten iron composition / wt,%

[0067]

[0068] Table 4 shows the distribution ratio of elements in slag, iron, and gas.

[0069]

[0070] Table 5 Blast Furnace Smelting Parameters

[0071]

[0072] In addition, the combustion rate of bituminous coal with a volatile matter content of 31% in this embodiment was tested using a blast furnace pulverized coal injection simulation test device, and its combustion rate was measured to be 75%.

[0073] Based on the above parameters, overall furnace energy and mass balance calculations (i.e., material balance calculations and overall furnace heat balance calculations) and regional energy and mass balance calculations (i.e., calculations of theoretical combustion temperature in the tuyeres swirl zone) were performed. The resulting blast furnace material balance table and overall furnace heat balance table for the baseline period are shown in Tables 6 and 7, respectively.

[0074] Table 6. Blast Furnace Material Balance Sheet for Base Period

[0075]

[0076] Table 7. Overall Furnace Heat Balance Table for Base Period

[0077]

[0078] The blast furnace heat loss in the table above is calculated using the following formula:

[0079]

[0080] In the formula, η HL For blast furnace heat loss, %; Q Z Total heat expenditure; Q YF Q represents the total heat consumed in the decomposition of oxides. S Heat consumption for desulfurization; Q Fuel-F The heat consumed by the decomposition of injected fuel; Q slag Enthalpy carried away by slag; Q pig-iron The enthalpy carried away by molten iron; Qdust The heat carried away by the furnace dust; Q gas The heat carried away by the gas at the top of the furnace; Heat is consumed during the decomposition of water; This is the heat loss due to carbon melting.

[0081] Similarly, the theoretical combustion temperature is calculated using the following formula:

[0082]

[0083] In the formula, T f Q is the theoretical combustion temperature; ck The heat released by the combustion of coke; Q cm The heat released by the combustion of pulverized coal; H b Sensible heat introduced by the oxygen-enriched blower; H ck Sensible heat introduced by coke; H m Sensible heat introduced by pulverized coal; H gas The sensible heat introduced by the pulverized coal carrier gas; Q w-g The water-gas reaction is endothermic; Q decom The fuel decomposition absorbs heat; Q gas The carrier gas absorbs heat; V g For the volume of gas in the hearth; m a The ash content of coke and fuel burned in front of the tuyeres; m w C represents the amount of unburned fuel. pg The heat capacity of the gas in the furnace hearth; C a Specific heat capacity of ash; C w This is the specific heat capacity of unburned fuel.

[0084] Among them, the heat released by pulverized coal combustion is Q cm The following formula is used for calculation:

[0085]

[0086] In the formula, q cm The heat released when one kg of carbon in pulverized coal burns to CO is taken as the same value as the heat of carbon combustion in coke, which is 4.18 × 2340 kJ·kg. -1 η represents the combustion rate of pulverized coal, which was measured to be 75% in this embodiment; W M The hourly pulverized coal injection rate is expressed in kJ·h. -1 C M The carbon content (including fixed C) in pulverized coal, %; H2O M The moisture content of pulverized coal is %.

[0087] The basicity of slag is calculated using the following formula:

[0088]

[0089] In the formula, R is the binary basicity of the slag; The content of CaO in the slag, in kg / t; The content of SiO2 in the slag is expressed in kg / t.

[0090] The specific calculation methods for the parameters involved in the above formulas are well known in the field. To avoid being too lengthy, the specific calculation process will not be listed here.

[0091] After calculation according to the above formula, the final blast furnace heat loss for the baseline period obtained in this embodiment is 5.26%, the theoretical combustion temperature is 2371℃, and the slag basicity is 1.14.

[0092] S2. Maintain the blast furnace process parameters of the baseline period, and only change the volatile matter content of the injected bituminous coal to 33% (in other embodiments of the present invention, it is also changed to 35% and 37% respectively). The pulverized coal combustion rates measured by the blast furnace pulverized coal injection simulation experimental device are 76%, 80%, and 85% respectively when the volatile matter content is 33%, 35%, and 37%. Then, perform the whole furnace energy and mass balance calculation and the regional energy and mass balance calculation in the same way as in step S1 to obtain the blast furnace heat loss, theoretical combustion temperature, slag basicity and other related parameters corresponding to the changed bituminous coal volatile matter content, as shown in Table 8.

[0093] Table 8. Relevant parameters of the blast furnace under different operating conditions before furnace temperature control.

[0094] Oxygen enrichment rate % 5.85 5.85 5.85 5.85 Theoretical combustion temperature (°C) 2371 2375 2373 2368 Slag alkalinity 1.144 1.147 1.153 1.162 % of sintered ore fed into the furnace 62 62 62 62 Coke ratio kg / t 396 396 396 396 Coal ratio kg / t 150 150 150 150 fuel ratio kg / t 546 546 546 546 <![CDATA[Blast air volume m 3 / t]]> 915.56 902.76 893.48 886.45 ore kg / t 1628.93 1628.91 1628.86 1628.79 Slag quantity kg / t 330.34 329.86 328.86 327.39 <![CDATA[H₂ utilization rate %]]> 0.4990 0.5000 0.5000 0.5000 CO utilization rate % 0.4531 0.4555 0.4569 0.4577 <![CDATA[Bosh gas volume m 3 / t]]> 1357.22 1344.15 1335.59 1329.89 Material balance error % 0.01 0.01 0.02 0.02 Heat loss % 5.26 4.85 4.58 4.41

[0095] As shown in Table 8, under the condition that the oxygen enrichment rate, coke ratio, coal ratio and fuel ratio remain unchanged, as the volatile matter content in bituminous coal increases, the basicity of blast furnace slag gradually increases, the blast volume gradually decreases, and the theoretical combustion temperature first rises and then falls, resulting in fluctuations. Meanwhile, the heat loss of the blast furnace continues to decrease, leading to unstable blast furnace temperature.

[0096] S3. Based on step S2, keep the coke ratio and volatile matter content of bituminous coal unchanged, adjust the sinter feed ratio, oxygen enrichment rate and coal ratio to make the calculated blast furnace heat loss, theoretical combustion temperature and slag basicity consistent with the corresponding parameter values ​​of the baseline period in step S1, obtain the actual process parameters corresponding to the changed bituminous coal volatile matter content, and complete the furnace temperature control.

[0097] Taking the change of the volatile matter content of bituminous coal to 33% in this embodiment as an example, the specific adjustment method is as follows:

[0098] First, the slag basicity was controlled by adjusting the proportion of sinter fed into the furnace. Using the baseline period with a volatile matter content of 31% and a slag basicity of 1.144 as the standard, in order to reduce the slag basicity corresponding to a volatile matter content of 33%, the proportion of sinter fed into the furnace was gradually reduced from 62%, and the calculated slag basicity results were observed. When the proportion of sinter fed into the furnace was reduced to 61.8%, the slag basicity was reduced to 1.144, which was consistent with the value of the baseline period, thus completing the control of the proportion of sinter fed into the furnace.

[0099] Then, the blast furnace heat loss was controlled by adjusting the coal ratio. Using the baseline period's blast furnace heat loss of 5.26% (corresponding to 31% volatile matter) as a standard, to increase the blast furnace heat loss at 33% volatile matter, the coal ratio was gradually increased from 150 kg / t, and the calculated blast furnace heat loss was observed. When the coal ratio increased to 154 kg / t, the blast furnace heat loss also increased to 5.26%, consistent with the baseline period. At this point, the theoretical combustion temperature decreased to 2370℃. Next, the theoretical combustion temperature was controlled by adjusting the oxygen enrichment rate. Using the baseline period's theoretical combustion temperature of 2371℃ (corresponding to 31% volatile matter) as a standard, to maintain consistency with the baseline period's theoretical combustion temperature at 33% volatile matter, the oxygen enrichment rate was gradually increased from 5.85%, and the calculated theoretical combustion temperature was observed. When the oxygen enrichment rate increased to 5.88%, the theoretical combustion temperature also increased from 2370℃ to 2371℃, consistent with the baseline period. At this point, the blast furnace heat loss decreased to 5.24%. The coal ratio was then adjusted again, still using 5.26% as the standard, gradually increasing from 154 kg / t, and the calculated blast furnace heat loss was observed. When the coal ratio reached 154.2 kg / t, the blast furnace heat loss also increased to 5.26%, consistent with the baseline period. At this point, the theoretical combustion temperature decreased to 2370.8℃, with an error of 0.2℃ from the baseline period, within the allowable error range. After rounding, it was recorded as 2371℃, consistent with the baseline period. At this point, both the blast furnace heat loss and the theoretical combustion temperature were consistent with the corresponding values ​​of the baseline period, thus completing the adjustment of the coal ratio and oxygen enrichment rate.

[0100] Similarly, by changing the volatile matter content of bituminous coal to 35% and 37% respectively, the sinter feed ratio, coal ratio, and oxygen enrichment rate can be adjusted in the same way as described above to ensure that the adjusted slag basicity, blast furnace heat loss, and theoretical combustion temperature remain consistent with the baseline period. The relevant parameters for blast furnace operation corresponding to different bituminous coal volatile matter contents are shown in Table 9.

[0101] Table 9 shows the relevant parameters of the blast furnace under different operating conditions after furnace temperature control.

[0102]

[0103]

[0104] As shown in Table 9, when the volatile matter content of bituminous coal increases, by keeping the coke ratio constant, reducing the proportion of sintered ore fed into the furnace, increasing the coal ratio, and increasing the oxygen enrichment rate, the blast furnace heat loss, theoretical combustion temperature, and slag basicity can be kept basically unchanged compared with the baseline period. This indirectly controls parameters such as blast volume, ore quantity, slag quantity, furnace gas quantity, H2 and CO utilization rate, thereby achieving furnace temperature control and ensuring normal and stable production after the blast furnace is fully injected with high volatile matter bituminous coal.

[0105] In summary, this invention provides a method for controlling the furnace temperature of blast furnaces using high-volatile bituminous coal injection, belonging to the field of blast furnace ironmaking calculations. This invention determines the blast furnace heat loss, theoretical combustion temperature, and slag basicity during the baseline period through whole-furnace energy and mass balance calculations and regional energy and mass balance calculations. Then, by adjusting the volatile content of the bituminous coal and maintaining a constant blast furnace coke ratio, the invention comprehensively adjusts the sinter feed ratio, coal ratio, and oxygen enrichment rate to keep the blast furnace heat loss, theoretical combustion temperature, and slag basicity essentially constant. This indirectly controls parameters such as blast volume, ore quantity, slag quantity, furnace gas quantity, H2 and CO utilization rates, thereby achieving furnace temperature control to ensure normal and stable production after the injection of high-volatile bituminous coal into the blast furnace.

[0106] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for temperature control in a blast furnace using high-volatile bituminous coal injection, characterized in that, Includes the following steps: S1. Pre-set the blast furnace process parameters for the reference period, and determine the blast furnace heat loss, theoretical combustion temperature and slag basicity for the reference period through whole furnace energy and mass balance calculation and regional energy and mass balance calculation. S2. Keep the blast furnace process parameters of the baseline period, only change the volatile matter content of the injected bituminous coal, and then obtain the blast furnace heat loss, theoretical combustion temperature and slag basicity corresponding to the changed bituminous coal volatile matter content through whole furnace energy quality balance calculation and regional energy quality balance calculation. S3. Based on step S2, keep the coke ratio and the volatile matter content of bituminous coal unchanged, adjust the sinter feed ratio, oxygen enrichment rate and coal ratio, so that the calculated blast furnace heat loss, theoretical combustion temperature and slag basicity are consistent with the corresponding parameter values ​​of the baseline period in step S1, obtain the actual process parameters corresponding to the changed bituminous coal volatile matter content, and complete the furnace temperature control. In step S3, the adjustment methods for the sinter feed ratio, oxygen enrichment rate, and coal ratio are as follows: first, gradually increase or gradually decrease the sinter feed ratio to keep the slag basicity consistent with the value of the baseline period; then, alternately adjust the coal ratio and oxygen enrichment rate to keep the blast furnace heat loss obtained after adjusting the coal ratio consistent with the value of the baseline period, and the theoretical combustion temperature obtained after adjusting the oxygen enrichment rate consistent with the value of the baseline period.

2. The method for controlling the furnace temperature of high-volatile bituminous coal injection in a blast furnace according to claim 1, characterized in that: The overall furnace energy and mass balance calculation includes material balance and overall furnace heat balance.

3. The method for temperature control in a blast furnace with high volatile matter bituminous coal injection according to claim 1, characterized in that: The energy-mass balance calculation in the region refers to the calculation of the theoretical combustion temperature in the vortex zone.

4. The method for controlling the furnace temperature of high-volatile bituminous coal injection in a blast furnace according to claim 1, characterized in that: The heat loss of the blast furnace is calculated according to the following formula: In the formula, For blast furnace heat loss, % Total heat expenditure; This represents the total heat consumed in the decomposition of oxides; Heat is consumed for desulfurization; The heat consumed by the decomposition of injected fuel; The enthalpy carried away by the slag; The enthalpy carried away by the molten iron; The heat carried away by the furnace dust; The heat carried away by the gas at the top of the furnace; Heat is consumed during the decomposition of water; This is the heat loss due to carbon melting.

5. The method for temperature control in a blast furnace with high volatile matter bituminous coal injection according to claim 1, characterized in that: The theoretical combustion temperature is calculated using the following formula: In the formula, The theoretical combustion temperature; The heat released during the combustion of coke; The heat is released by the combustion of pulverized coal; Sensible heat introduced by the oxygen-enriched blower; The sensible heat introduced by the coke; The sensible heat introduced by the pulverized coal; The sensible heat introduced by the pulverized coal carrier gas; Q w-g The water-gas reaction is endothermic; The fuel decomposes and absorbs heat; The carrier gas absorbs heat; This refers to the amount of gas in the furnace hearth. The ash content of the coke and fuel burned in front of the tuyeres; This refers to the amount of unburned fuel. The heat capacity of the gas in the furnace hearth; Specific heat capacity of ash; This is the specific heat capacity of unburned fuel.

6. The method for temperature control in a blast furnace with high volatile matter bituminous coal injection according to claim 5, characterized in that: The pulverized coal combustion rate corresponding to bituminous coal with different volatile matter contents was obtained by testing a blast furnace pulverized coal injection simulation experimental device and used for calculating the heat release of the pulverized coal combustion.

7. The method for temperature control in a blast furnace with high volatile matter bituminous coal injection according to claim 1, characterized in that: The alkalinity of the slag is calculated according to the following formula: In the formula, The basicity is binary basicity of slag; In the slag Content, kg / t; In the slag The content, kg / t.

8. The method for temperature control in a blast furnace with high volatile matter bituminous coal injection according to claim 1, characterized in that: In step S1, the volatile matter content of the base period bituminous coal is 31%; in step S2, the volatile matter content of the modified bituminous coal is 33% to 37%.

9. The method for temperature control in a blast furnace with high volatile matter bituminous coal injection according to claim 1, characterized in that: In step S1, the blast furnace process parameters include the composition and proportion of sinter, pellets and lump ore used in blast furnace smelting, the composition, coke ratio, coal ratio, preset pig iron composition and blast parameters of coke and bituminous coal used in blast furnace smelting.

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