Method for measuring and calculating ignition point of mixed pulverized coal for injection

Abstract

The invention relates to a method for measuring and calculating an ignition point of mixed pulverized coal for injection. The method comprises the following steps: 1) determining evaluation parameters of the mixed pulverized coal related to the ignition point; 2) grouping and setting contribution values of each evaluation parameter to ignition point measurement and calculation; 3) respectively setting correlation coefficients of each group of evaluation parameters for mixed pulverized coal ignition point measurement and calculation; and 4) establishing a mixed pulverized coal ignition point calculation formula composed of each group of evaluation parameters, and setting an error compensation coefficient. According to the method, on the basis of fully considering the pulverized coal components related to the ignition point of the mixed pulverized coal, the ignition point of the mixed pulverized coal for injection with different components is accurately measured and calculated, so that a reliable basis is provided for pulverized coal preparation safety, coal type selection and matching and blast furnace coal injection process optimization related to a blast furnace coal injection process.

Description

Technical Field

[0001] The invention relates to the technical field of steel smelting, and in particular to a method for calculating the ignition point of mixed coal powder for injection. Background Art

[0002] As the most economical method of making pig iron, blast furnace ironmaking still has an irreplaceable position. Most of the current steel products are processed and manufactured from molten iron produced by blast furnace smelting. Many studies and production practices have also proved that blast furnaces are still the production equipment with the highest thermal utilization efficiency, that is, the best thermal efficiency can be achieved in blast furnaces with the least energy consumption. Therefore, economic efficiency is also the reason why it is the mainstream ironmaking equipment.

[0003] In the process of smelting iron-containing charge in the blast furnace, the reduction reaction of the charge in the furnace is mostly endothermic. From the perspective of energy balance, external heat supplement is needed to maintain the reaction process in the furnace. The external heat source of the blast furnace is mainly composed of the following two parts: one is the hot air blown in from the outside, whose temperature is usually maintained between 1100℃ and 1350℃, which can provide 20% to 30% of the heat required for the reaction in the furnace; and the main source of heat in the furnace is the added fuel, mainly including the coke fed into the furnace and the pulverized coal injection. These fuels provide most of the heat energy required for the reaction in the furnace and are the basis for maintaining the smooth progress of the reaction in the furnace.

[0004] As the main fuel for blast furnace smelting, coke and pulverized coal have both similarities and differences in their roles in the furnace. The commonality between the two is that they both play the role of carburizing agent, heating agent, and reducing agent, while the difference is that coke also plays the role of material column skeleton in the blast furnace, while pulverized coal injection does not have this function. In addition, there are large differences in the morphology and performance of the two. The coke entering the furnace is the product of coal powder after dry distillation. Its appearance is blocky and the particle size requirement is generally not less than 25mm; while pulverized coal injection is composed of fine-grained powder, and the general particle size control requirement is that the proportion of particles less than 0.071mm is not less than 70%. At the same time, the evaluation performance of the two is also different. The usual evaluation indicators of coke include drum strength M40, wear resistance M10, compressive strength, coke thermal performance CRI and post-reaction strength CSR; while the evaluation indicators of pulverized coal injection usually include calorific value, grindability, ash melting point, ignition point (burning point), combustion rate, coking property, etc.

[0005] Among the many indicators for evaluating pulverized coal injection, the ignition point is the most important one. The ignition point indicator is mainly related to the safety of the pulverizing system and the utilization effect of pulverized coal in the furnace. Generally speaking, the higher the ignition point, the more beneficial it is to the safety of the pulverizing system (for example, adding a high proportion of anthracite can have an explosion-proof effect). The lower the ignition point of the pulverized coal injected into the furnace, the lower the temperature when the pulverized coal starts to burn. The mixed pulverized coal with a low ignition point will promote the combustion of pulverized coal in the limited space of the cyclonic zone, thereby increasing the combustion rate of pulverized coal and improving the heat utilization effect of pulverized coal in the furnace. Since the requirements for the above two properties are contradictory, it is necessary to analyze the ignition point of the mixed pulverized coal in order to find a more suitable mixed pulverized coal ratio.

[0006] At present, the main analytical methods for the ignition point of coal powder are analytical calculation method and instrumental analysis method. The analytical calculation method is to analyze and calculate the ignition temperature of coal powder based on relevant theories and experiments, such as the "Calculation method of ignition temperature of coal powder airflow of a single type of coal" disclosed in the Chinese patent application with publication number CN111274526A, the "Calculation method of ignition temperature of mixed coal powder airflow after two single types of coal are blended" disclosed in the Chinese patent application with publication number CN111859711A, the "Test and evaluation method of ignition performance of thermal coal" disclosed in the Chinese patent application with publication number CN108680699A, and the "Measurement method of ignition point of air-powder mixture in coal-fired boiler" disclosed in the Chinese invention patent with authorization announcement number CN102288632B. The instrumental analysis method uses a special coal powder ignition point measuring instrument to analyze the ignition point of different types of coal powder. The ignition point index obtained can provide the necessary basic reference for coal powder storage, transportation, and injection. For example, the Chinese utility model patent with authorization announcement number CN206450622U discloses "a multifunctional ignition point detection device", and the Chinese utility model patent with authorization announcement number CN216051473U discloses "a multi-sample synchronous coal ignition point detection device". However, the existing instruments for ignition point determination are mainly used for testing a single type of coal, and there are few that can test mixed coal powder, especially high-ignition point coal powder and alternative coal types used as blast furnace injection coal powder. The structure and composition of the mixed coal powder used for blast furnace injection are complex. When the existing single-type coal powder ignition point tester is used to measure and analyze the mixed coal powder, there is often a certain degree of error between the measurement results and the actual usage. Moreover, the above-mentioned detection device or analysis method does not involve the ignition point determination of blast furnace injection coal powder, especially mixed coal powder with different coal types (including alternative coal types).

[0007] Among the currently available literature and materials at home and abroad, those related to the ignition point of coal powder include "Analysis of the method for determining the ignition point in coal combustion experiments" (Chemical Engineering Design Communications, Vol. 45, No. 12, 2019, p. 238), "Research on the ignition point and microstructure change characteristics of weakly sticky coal during oxidation" (Coal Mine Safety, Vol. 50, No. 1, 2019, pp. 29-37), "Investigation on the spontaneous combustion point of coal and its influencing factors" (Coal Mine Safety, Vol. 40, No. 1, 2009, pp. 65-69), etc. However, the above literature and materials mainly focus on the impact of the ignition point on the safety of coal combustion, and do not involve the method of analyzing the ignition point of mixed coal powder for blast furnace injection through the composition of the mixed coal powder. Summary of the invention

[0008] The present invention provides a method for calculating the ignition point of mixed pulverized coal for blast furnace injection. On the basis of fully considering the pulverized coal components related to the ignition point of the mixed pulverized coal, the ignition point of mixed pulverized coal for injection with different components is accurately calculated, thereby providing a reliable basis for the pulverizing safety, coal type selection and matching involved in the blast furnace coal injection process, and the optimization of the blast furnace coal injection process.

[0009] In order to achieve the above object, the present invention adopts the following technical solutions:

[0010] A method for calculating the ignition point of mixed pulverized coal for injection comprises the following steps:

[0011] 1) Determine the evaluation parameters related to the ignition point of the mixed coal powder, including fixed carbon content, volatile matter content, ash content and sulfur content, as well as the silicon dioxide content, aluminum oxide content, calcium oxide content and magnesium oxide content in the ash;

[0012] 2) According to the historical data recorded in the blast furnace production and operation database, the contribution values ​​of various evaluation parameters to the ignition point measurement are set in groups; among them, the fixed carbon content and the volatile matter content are the first group of evaluation parameters, the ash content and the sulfur content are the second group of evaluation parameters, and the silicon dioxide content, aluminum oxide content, calcium oxide content and magnesium oxide content in the ash are the third group of evaluation parameters;

[0013] 3) According to the historical data recorded in the blast furnace production and operation database, the correlation coefficients of each group of evaluation parameters for the ignition point calculation of the mixed coal powder are set respectively;

[0014] 4) Establish a calculation formula for the ignition point of mixed pulverized coal composed of each group of evaluation parameters, and set the error compensation coefficient based on the historical data recorded in the blast furnace production and operation database;

[0015] The calculation formula for the ignition point of mixed pulverized coal for injection is:

[0016]

[0017] Where:

[0018] KP--ignition point of mixed pulverized coal for injection, ℃;

[0019] F C --Fixed carbon content in mixed coal powder, %;

[0020] V--volatile matter content in mixed coal powder, %;

[0021] A--ash content in mixed coal powder, %;

[0022] S--Sulfur content in mixed coal powder, %;

[0023] ω(SiO2)--Silicon dioxide content in mixed coal powder ash, %;

[0024] ω(Al2O3)--aluminum oxide content in mixed coal powder ash, %;

[0025] ω(CaO)--Calcium oxide content in mixed coal powder ash, %;

[0026] ω(MgO)--magnesium oxide content in mixed coal powder ash, %;

[0027] K--error compensation coefficient, which is a constant and takes the value of 198.62, ℃;

[0028] m1--the correlation system of the first set of evaluation parameters, which is a constant and takes the value of 78.60, ℃;

[0029] m2--Correlation coefficient of the second group of evaluation parameters, which is a constant and takes the value of 14.77, ℃;

[0030] m3--Correlation coefficient of the third group of evaluation parameters, which is a constant and takes the value of 5.61, ℃.

[0031] Furthermore, the mixed coal powder is composed of two or more different types of coal powder, and the different types of coal powder include anthracite, lean coal, lean lean coal, bituminous coal, lignite and alternative coal.

[0032] Furthermore, the alternative coal types include one or more of lignite, CDQ powder, upgraded coal, biomass fuel, and blast furnace dust ash.

[0033] Furthermore, the biomass fuel includes one or more of charcoal, activated carbon, straw, fruit wood shell, and rice husk.

[0034] Furthermore, the blast furnace dust ash includes one or more of the following: coke trough dust ash, furnace top dust ash, and furnace front dust ash.

[0035] Furthermore, the mixed coal powder has a fixed carbon content of 50% to 88%, a volatile matter content of 6% to 40%, an ash content of 5% to 20%, and a sulfur content of 0.2% to 2.5%.

[0036] Furthermore, the SiO2 content in the mixed coal powder ash is 15% to 65%, the Al2O3 content is 5% to 40%, the CaO content is 1% to 15%, and the MgO content is 0.2% to 10%.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] On the basis of fully considering the coal powder components related to the ignition point of the mixed coal powder, the ignition point of the mixed coal powder with different components for injection is accurately calculated, thereby providing a reliable basis for the pulverizing safety, coal type selection and matching involved in the blast furnace coal injection process, as well as the optimization of the blast furnace coal injection process. DETAILED DESCRIPTION

[0039] The method for calculating the ignition point of mixed pulverized coal for injection described in the present invention comprises the following steps:

[0040] 1) Determine the evaluation parameters related to the ignition point of the mixed coal powder, including fixed carbon content, volatile matter content, ash content and sulfur content, as well as the silicon dioxide content, aluminum oxide content, calcium oxide content and magnesium oxide content in the ash;

[0041] 2) According to the historical data recorded in the blast furnace production and operation database, the contribution values ​​of various evaluation parameters to the ignition point measurement are set in groups; among them, the fixed carbon content and the volatile matter content are the first group of evaluation parameters, the ash content and the sulfur content are the second group of evaluation parameters, and the silicon dioxide content, aluminum oxide content, calcium oxide content and magnesium oxide content in the ash are the third group of evaluation parameters;

[0042] 3) According to the historical data recorded in the blast furnace production and operation database, the correlation coefficients of each group of evaluation parameters for the ignition point calculation of the mixed coal powder are set respectively;

[0043] 4) Establish a calculation formula for the ignition point of mixed pulverized coal composed of each group of evaluation parameters, and set the error compensation coefficient based on the historical data recorded in the blast furnace production and operation database;

[0044] The calculation formula for the ignition point of mixed pulverized coal for injection is:

[0045]

[0046] Where:

[0047] KP--ignition point of mixed pulverized coal for injection, ℃;

[0048] FC --Fixed carbon content in mixed coal powder, %;

[0049] V--volatile matter content in mixed coal powder, %;

[0050] A--ash content in mixed coal powder, %;

[0051] S--Sulfur content in mixed coal powder, %;

[0052] ω(SiO2)--Silicon dioxide content in mixed coal powder ash, %;

[0053] ω(Al2O3)--aluminum oxide content in mixed coal powder ash, %;

[0054] ω(CaO)--Calcium oxide content in mixed coal powder ash, %;

[0055] ω(MgO)--magnesium oxide content in mixed coal powder ash, %;

[0056] K--error compensation coefficient, which is a constant and takes the value of 198.62, ℃;

[0057] m1--the correlation system of the first set of evaluation parameters, which is a constant and takes the value of 78.60, ℃;

[0058] m2--Correlation coefficient of the second group of evaluation parameters, which is a constant and takes the value of 14.77, ℃;

[0059] m3--Correlation coefficient of the third group of evaluation parameters, which is a constant and takes the value of 5.61, ℃.

[0060] Furthermore, the mixed coal powder is composed of two or more different types of coal powder, and the different types of coal powder include anthracite, lean coal, lean lean coal, bituminous coal, lignite and alternative coal.

[0061] Furthermore, the alternative coal types include one or more of lignite, CDQ powder, upgraded coal, biomass fuel, and blast furnace dust ash.

[0062] Furthermore, the biomass fuel includes one or more of charcoal, activated carbon, straw, fruit wood shell, and rice husk.

[0063] Furthermore, the blast furnace dust ash includes one or more of the following: coke trough dust ash, furnace top dust ash, and furnace front dust ash.

[0064] Furthermore, the mixed coal powder has a fixed carbon content of 50% to 88%, a volatile matter content of 6% to 40%, an ash content of 5% to 20%, and a sulfur content of 0.2% to 2.5%.

[0065] Furthermore, the SiO2 content in the mixed coal powder ash is 15% to 65%, the Al2O3 content is 5% to 40%, the CaO content is 1% to 15%, and the MgO content is 0.2% to 10%.

[0066] In order to more intuitively embody the present invention, the embodiments of the present invention are further described in conjunction with examples. The following examples are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any technical solution that can be obviously obtained by a person skilled in the art within the technical scope disclosed in the present invention, including simple changes or equivalent replacements, is within the protection scope of the present invention.

[0067] [Example 1]

[0068] This example uses a steel plant with an effective furnace capacity of 300m 3 Taking pulverized coal injection in blast furnace as an example, the composition ratio of mixed pulverized coal for blast furnace injection is shown in Table 1-1.

[0069] Table 1-1 Composition ratio of mixed pulverized coal for blast furnace injection

[0070]

[0071] The composition of the mixed coal powder for blast furnace injection is detailed in Table 1-2.

[0072] Table 1-2 Composition of mixed pulverized coal for blast furnace injection, wt%

[0073]

[0074] The ash composition of mixed coal powder for blast furnace injection is shown in Table 1-3.

[0075] Table 1-3 Composition of mixed coal fly ash for blast furnace injection, wt%

[0076]

[0077] Formula 1 is used to calculate the ignition point of the mixed pulverized coal for injection. The calculation results are shown in Table 1-4.

[0078] Table 1-4 Ignition point of mixed pulverized coal for injection, ℃

[0079]

[0080] According to the calculation results, for an effective furnace capacity of 300m 3The ignition point of the mixed coal powder injected into a blast furnace is 353.33°C, which means that under the coal type ratio in this embodiment, the ignition point of the mixed coal powder can fully meet the needs of the safety of the pulverizing system and the combustion effect of the coal powder in the furnace (the industry generally requires the ignition point to be controlled between 330°C and 380°C). The coal type matching scheme is a more reasonable coal mixing structure, which is conducive to low-consumption and high-efficiency production of blast furnaces.

[0081] [Example 2]

[0082] This example uses a steel plant with an effective furnace capacity of 1800m 3 Taking pulverized coal injection in blast furnace as an example, the composition ratio of mixed pulverized coal for blast furnace injection is shown in Table 2-1.

[0083] Table 2-1 Composition ratio of mixed pulverized coal for blast furnace injection

[0084]

[0085] The composition of the mixed coal powder for blast furnace injection is detailed in Table 2-2.

[0086] Table 2-2 Composition of mixed pulverized coal for blast furnace injection, wt%

[0087]

[0088] The ash composition of mixed coal powder for blast furnace injection is shown in Table 2-3.

[0089] Table 2-3 Composition of mixed coal fly ash for blast furnace injection, wt%

[0090]

[0091] Formula 1 is used to calculate the ignition point of the mixed coal powder for injection. The calculation results are shown in Table 2-4.

[0092] Table 2-4 Ignition point of mixed pulverized coal for injection, ℃

[0093]

[0094] According to the calculation results, for an effective furnace capacity of 1800m 3 The ignition point of the mixed pulverized coal injected into a blast furnace was 358.37°C, indicating that under the coal type ratio in this embodiment, the ignition point of the mixed pulverized coal can fully meet the needs of the safety of the pulverizing system and the combustion effect of the pulverized coal in the furnace. The coal type matching scheme is a more reasonable coal mixing structure, which is conducive to low-consumption and high-efficiency production of blast furnaces.

[0095] [Example 3]

[0096] This example uses a steel plant with an effective furnace capacity of 2580m 3Taking pulverized coal injection in blast furnace as an example, the composition ratio of mixed pulverized coal for blast furnace injection is shown in Table 3-1.

[0097] Table 3-1 Composition ratio of mixed pulverized coal for blast furnace injection

[0098]

[0099] The composition of the mixed coal powder for blast furnace injection is detailed in Table 3-2.

[0100] Table 3-2 Composition of mixed pulverized coal for blast furnace injection, wt%

[0101]

[0102] The ash composition of mixed coal powder for blast furnace injection is shown in Table 3-3.

[0103] Table 3-3 Composition of mixed coal fly ash for blast furnace injection, wt%

[0104]

[0105] Formula 1 is used to calculate the ignition point of the mixed coal powder for injection. The calculation results are shown in Table 3-4.

[0106] Table 3-4 Ignition point of mixed pulverized coal for injection, ℃

[0107]

[0108] According to the calculation results, for an effective furnace capacity of 2580m 3 The ignition point of the mixed pulverized coal injected into a blast furnace was 348.77°C, indicating that under the coal type ratio in this embodiment, the ignition point of the mixed pulverized coal can fully meet the needs of the safety of the pulverizing system and the combustion effect of the pulverized coal in the furnace. The coal type matching scheme is a more reasonable coal mixing structure, which is conducive to low-consumption and high-efficiency production of blast furnaces.

[0109] [Example 4]

[0110] This example uses a steel plant with an effective furnace capacity of 3200m 3 Taking pulverized coal injection in blast furnace as an example, the composition ratio of mixed pulverized coal for blast furnace injection is shown in Table 4-1.

[0111] Table 4-1 Composition ratio of mixed pulverized coal for blast furnace injection

[0112]

[0113] The composition of the mixed coal powder for blast furnace injection is detailed in Table 4-2.

[0114] Table 4-2 Composition of mixed pulverized coal for blast furnace injection, wt%

[0115]

[0116] The ash composition of mixed coal powder for blast furnace injection is shown in Table 4-3.

[0117] Table 4-3 Composition of mixed coal fly ash for blast furnace injection, wt%

[0118]

[0119] Formula 1 is used to calculate the ignition point of the mixed coal powder for injection. The calculation results are shown in Table 4-4.

[0120] Table 4-4 Ignition point of mixed pulverized coal for injection, ℃

[0121]

[0122] According to the calculation results, for an effective furnace capacity of 3200m 3 The ignition point of the mixed pulverized coal injected into a blast furnace was 344.05°C, indicating that under the coal type ratio in this embodiment, the ignition point of the mixed pulverized coal can fully meet the needs of the safety of the pulverizing system and the combustion effect of the pulverized coal in the furnace. The coal type matching scheme is a more reasonable coal mixing structure, which is conducive to low-consumption and high-efficiency production of blast furnaces.

[0123] [Example 5]

[0124] This example uses a steel plant with an effective furnace capacity of 4038m 3 Taking pulverized coal injection in blast furnace as an example, the composition ratio of mixed pulverized coal for blast furnace injection is shown in Table 5-1.

[0125] Table 5-1 Composition ratio of mixed pulverized coal for blast furnace injection

[0126]

[0127] The composition of the mixed coal powder for blast furnace injection is detailed in Table 5-2.

[0128] Table 5-2 Composition of mixed pulverized coal for blast furnace injection, wt%

[0129]

[0130] The ash composition of mixed coal powder for blast furnace injection is detailed in Table 5-3.

[0131] Table 5-3 Composition of mixed coal fly ash for blast furnace injection, wt%

[0132]

[0133] Formula 1 is used to calculate the ignition point of the mixed coal powder for injection. The calculation results are shown in Table 5-4.

[0134] Table 5-4 Ignition point of mixed pulverized coal for injection, ℃

[0135]

[0136] According to the calculation results, for an effective furnace capacity of 4038m 3 The ignition point of the mixed pulverized coal injected into a blast furnace was 342.60°C, indicating that under the coal type ratio in this embodiment, the ignition point of the mixed pulverized coal can fully meet the needs of the safety of the pulverizing system and the combustion effect of the pulverized coal in the furnace. The coal type matching scheme is a more reasonable coal mixing structure, which is conducive to low-consumption and high-efficiency production of blast furnaces.

[0137] [Example 6]

[0138] This example uses a steel plant with an effective furnace capacity of 5500m 3 Taking pulverized coal injection in blast furnace as an example, the composition ratio of mixed pulverized coal for blast furnace injection is shown in Table 6-1.

[0139] Table 6-1 Composition ratio of mixed pulverized coal for blast furnace injection

[0140]

[0141] The composition of the mixed coal powder for blast furnace injection is detailed in Table 6-2.

[0142] Table 6-2 Composition of mixed pulverized coal for blast furnace injection, wt%

[0143]

[0144] The ash composition of mixed coal powder for blast furnace injection is detailed in Table 6-3.

[0145] Table 6-3 Composition of mixed coal fly ash for blast furnace injection, wt%

[0146]

[0147] Formula 1 is used to calculate the ignition point of the mixed coal powder for injection. The calculation results are shown in Table 6-4.

[0148] Table 6-4 Ignition point of mixed pulverized coal for injection, ℃

[0149]

[0150] According to the calculation results, for an effective furnace capacity of 5500m 3 The ignition point of the mixed pulverized coal injected into a blast furnace was 341.38°C, indicating that under the coal type ratio in this embodiment, the ignition point of the mixed pulverized coal can fully meet the needs of the safety of the pulverizing system and the combustion effect of the pulverized coal in the furnace. The coal type matching scheme is a more reasonable coal mixing structure, which is conducive to low-consumption and high-efficiency production of blast furnaces.

[0151] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for calculating the ignition point of mixed pulverized coal for injection, characterized in that: The following steps are involved: 1) Determine the evaluation parameters related to the ignition point of the mixed coal powder, including fixed carbon content, volatile matter content, ash content and sulfur content, as well as the silicon dioxide content, aluminum oxide content, calcium oxide content and magnesium oxide content in the ash; 2) According to the historical data recorded in the blast furnace production and operation database, the contribution values ​​of various evaluation parameters to the ignition point measurement are set in groups; among them, the fixed carbon content and the volatile matter content are the first group of evaluation parameters, the ash content and the sulfur content are the second group of evaluation parameters, and the silicon dioxide content, aluminum oxide content, calcium oxide content and magnesium oxide content in the ash are the third group of evaluation parameters; 3) According to the historical data recorded in the blast furnace production and operation database, the correlation coefficients of each group of evaluation parameters for the ignition point calculation of the mixed coal powder are set respectively; 4) Establish a calculation formula for the ignition point of mixed pulverized coal composed of each group of evaluation parameters, and set the error compensation coefficient based on the historical data recorded in the blast furnace production and operation database; The calculation formula for the ignition point of mixed pulverized coal for injection is: Where: KP--ignition point of mixed pulverized coal for injection, ℃; F C --Fixed carbon content in mixed coal powder, %; V--volatile matter content in mixed coal powder, %; A--ash content in mixed coal powder, %; S--Sulfur content in mixed coal powder, %; ω(SiO2)--Silicon dioxide content in mixed coal powder ash, %; ω(Al2O3)--aluminum oxide content in mixed coal powder ash, %; ω(CaO)--Calcium oxide content in mixed coal powder ash, %; ω(MgO)--magnesium oxide content in mixed coal powder ash, %; K--error compensation coefficient, which is a constant and takes the value of 198.62, ℃; m1--the correlation system of the first set of evaluation parameters, which is a constant and takes the value of 78.60, ℃; m2--Correlation coefficient of the second group of evaluation parameters, which is a constant and takes the value of 14.77, ℃; m3--Correlation coefficient of the third group of evaluation parameters, which is a constant and takes the value of 5.61, ℃.

2. The method for calculating the ignition point of mixed pulverized coal for injection according to claim 1, characterized in that: The mixed coal powder is composed of two or more different types of coal powder, and the different types of coal powder include anthracite, lean coal, lean lean coal, bituminous coal, lignite and alternative coal.

3. The method for calculating the ignition point of mixed pulverized coal for injection according to claim 2, characterized in that: The alternative coal types include one or more of lignite, CDQ powder, upgraded coal, biomass fuel, and blast furnace dust ash.

4. The method for calculating the ignition point of mixed pulverized coal for injection according to claim 3, characterized in that: The biomass fuel includes one or more of charcoal, activated carbon, straw, fruit wood shell and rice husk.

5. The method for calculating the ignition point of mixed pulverized coal for injection according to claim 3, characterized in that: The blast furnace dust removal ash includes one or more of the following: ore coke trough dust removal ash, furnace top dust removal ash, and furnace front dust removal ash.

6. The method for calculating the ignition point of mixed pulverized coal for injection according to claim 1, characterized in that: The mixed coal powder has a fixed carbon content of 50% to 88%, a volatile matter content of 6% to 40%, an ash content of 5% to 20%, and a sulfur content of 0.2% to 2.5%.

7. The method for calculating the ignition point of mixed pulverized coal for injection according to claim 1, characterized in that: The SiO2 content in the mixed coal powder ash is 15% to 65%, the Al2O3 content is 5% to 40%, the CaO content is 1% to 15%, and the MgO content is 0.2% to 10%.

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