A method for improving the combustion efficiency of pulverized coal injected with oxygen enrichment in a blast furnace

Abstract

The present invention discloses a method for improving the combustion efficiency of pulverized coal with oxygen enrichment in a blast furnace, comprising the following steps: Step 1, prepare the raw materials charged into the blast furnace, the fuel charged into the furnace, and the injection materials. The raw materials charged into the furnace are sinter, pellet, and lump ore; the fuel charged into the furnace is large coke and coke breeze, and the pulverized coal injection material for the blast furnace is a mixed powder of bituminous coal + anthracite + blast furnace slag; Step 2, the blast furnace adopts a burden distribution mode of "restraining the peripheral gas flow + developing the central gas flow", and the mass percentage of the ore charged at the periphery is 33.3 - 35.7% of the ore batch; Step 3, the oxygen enrichment rate adopted by the blast furnace is 10 - 14%, and the air inlet area is adjusted according to the actual air volume of the blast furnace, with the actual wind speed being 285 - 300 m / s; Step 4, the blast furnace smelts with technical parameters of a hot blast temperature of 1250 - 1350 °C and a coal injection ratio of 190 - 220 kg / t·Fe, realizing the improvement of the combustion efficiency of pulverized coal with oxygen enrichment in the blast furnace. This method can increase the oxygen enrichment rate of the blast furnace blast, increase the output of the blast furnace, use a large proportion of high-volatile bituminous coal for injection, increase the coal ratio charged into the furnace, and reduce the coke consumption.

Description

Technical Field

[0001] The present invention relates to metallurgical technology, and particularly to a method for improving the combustion efficiency of pulverized coal injected into a blast furnace with oxygen enrichment. Background Art

[0002] The oxygen enrichment technology for blast furnaces has been implemented in different iron and steel enterprises for decades. It can be said that this technology has been relatively mature both in terms of the oxygen production process equipment and the specific application in blast furnaces, achieving the effects of increasing the blast furnace production capacity and reducing fuel consumption. Therefore, considering the importance of oxygen enrichment technology for blast furnace production, it is of great significance for iron and steel enterprises to increase the oxygen enrichment rate in the hot blast blown into the blast furnace on the premise of maintaining the stable and smooth operation of the blast furnace.

[0003] The main functions of oxygen enrichment injection in blast furnace production are as follows: (1) It can improve the pulverized coal replacement ratio, reduce coke consumption, and increase the pulverized coal injection ratio of the blast furnace; (2) During the process of intensifying smelting and increasing the production of the blast furnace, by increasing the oxygen enrichment rate, the gas recovery per ton of iron decreases, the total gas recovery increases, the N2 content in the recovered gas decreases, and the gas calorific value increases; (3) With the increase in iron production and gas recovery, the power generation of TRT also increases; (4) By increasing the oxygen enrichment rate, the net power consumption per ton of iron decreases, the power consumption efficiency of the blast furnace can be improved, which is beneficial to reducing the ironmaking cost.

[0004] As an important means of intensifying smelting, oxygen enrichment blowing can effectively increase the blast furnace production. Theoretically, for every 1% oxygen enrichment, the blast furnace can increase production by 4.76%. In practice, however, with the increase in the oxygen enrichment rate, the production increase effect of every 1% oxygen enrichment gradually decreases. For example, when the oxygen content in the air at the tuyere during production is 21 - 25%, for every 1% increase in O2, the production increase is 3.2 - 3.5%; when the oxygen content is 25 - 30%, for every 1% increase in O2, the production increase is 3%; when the oxygen content is 30 - 35%, for every 1% increase in O2, the production increase is 2.7%; when the oxygen enrichment reaches 40%, for every 1% increase in O2, the production increase is 2.4%.

[0005] The practice of pulverized coal injection in blast furnaces at home and abroad shows that the oxygen enrichment technology is the most effective measure to increase the theoretical tuyere temperature. Generally, it is considered that the theoretical combustion temperature increases after oxygen enrichment, and for every 1% increase in the oxygen enrichment rate, the theoretical combustion temperature increases by 45 - 50°C. Simply considering the compensation of the theoretical combustion temperature by pulverized coal decomposition, for every 1% increase in the oxygen enrichment rate, the pulverized coal injection rate can be increased by about 20 kg / t. According to the actual blast furnace production calculation, for every 1% increase in the oxygen enrichment rate in the blast, the pulverized coal injection rate increases by about 13 kg / t. Thus, it can be seen that oxygen enrichment and pulverized coal injection in the blast furnace are mutually conditional and interdependent. In fact, however, it is very difficult to achieve balance in this complementarity in industrial production, especially when the oxygen enrichment rate is above 10%. How to regulate between oxygen enrichment and pulverized coal injection still requires a large number of experimental explorations. Only by solving the problem of the quantity balance between oxygen enrichment and pulverized coal injection can the oxygen-enriched blast furnace smelting technology be comprehensively mastered.

[0006] The internationally leading PCI rate of blast furnaces is 266 kg / t. Baosteel has reached a level of 260 kg / t, and Shagang's 5800 m 3 The oxygen enrichment rate of blast furnaces has reached 10%. There are some deficiencies or defects in the oxygen enrichment and PCI technology of blast furnaces in most enterprises. For example, when the PCI rate of blast furnaces in some enterprises increases, a large amount of unburned pulverized coal appears at the same time. The coke ratio and fuel ratio do not decrease but increase, and the purpose of PCI is not achieved. At present, the theory and practice of a large amount of pulverized coal injection in blast furnaces at home and abroad show that as the amount of pulverized coal injection increases, the combustion rate of pulverized coal in the raceway decreases, and the amount of unburned pulverized coal blown out from the furnace top increases. The unburned pulverized coal has an adverse effect on the coke permeability of the cohesive zone, which will lead to a decrease in the blast furnace permeability and a reduction in the gas utilization rate.

[0007] In addition, to achieve carbon emission reduction, large oxygen-enriched blast furnaces will become a trend. After significantly increasing the oxygen enrichment, although the amount of pulverized coal injection increases, the blast furnace has a limited PCI capacity due to the changing environment. After a large amount of oxygen enrichment, the temperature of the tuyere raceway will increase. To cope with this, large oxygen-enriched blast furnaces often adopt humidified blowing. At present, some scholars believe that during the process of pressurized air entering the blast furnace, due to the increase in temperature, it has always been in an unsaturated state. During the gas leakage process in the blast furnace, the gas reaching the gap between the furnace shell and the cooling stave is at normal temperature and under pressure, and will reach a supersaturated state, thus continuously generating condensed water, causing the gasification and disappearance of the hot surface carbon bricks, triggering the collapse of the ceramic cup, or triggering the periodic thinning of the solidified iron layer, eroding the carbon bricks at the lower part of the hearth, and reducing the service life of the blast furnace.

[0008] Some scholars have believed through years of research and experiments that: by adding combustion improvers such as rare earth oxides like lanthanum oxide and cerium oxide, the combustion rate of pulverized coal can be effectively improved. However, since rare earths are controlled resources, and for the production of iron-making blast furnaces, due to the large amount of pulverized coal injection and continuous production, even if the addition ratio of the combustion improver is 1%, the demand for rare earths is extremely huge. Therefore, it is difficult to be applied industrially. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to provide a method for improving the combustion efficiency of pulverized coal injected with oxygen enrichment in blast furnaces in view of the above-mentioned deficiencies in the prior art, which can increase the oxygen enrichment rate of blast furnace blowing, increase the output of blast furnaces, use high-volatile bituminous coal for injection in a large proportion, increase the coal ratio in the furnace, and reduce the coke consumption.

[0010] The technical solution adopted by the present invention to solve the above-mentioned problems is as follows:

[0011] A method for improving the combustion efficiency of pulverized coal injected with oxygen enrichment in blast furnaces, comprising the following steps:

[0012] Step 1: Prepare the raw materials, fuels and injection materials for the blast furnace. The raw materials for the blast furnace are sinter, pellet and lump ore; the fuels for the blast furnace are large coke and coke breeze, and the injection material for the blast furnace is a mixed powder of bituminous coal + anthracite + blast furnace slag;

[0013] Step 2: The blast furnace adopts a burden distribution mode of "restraining the peripheral gas flow + developing the central gas flow", and the mass percentage of ore distributed at the periphery is 33.3 - 35.7% of the ore batch.

[0014] Step 3: The oxygen enrichment rate adopted by the blast furnace is 10 - 14%, the inlet air area is adjusted according to the actual air volume of the blast furnace, and the actual wind speed is controlled at 285 - 300 m / s.

[0015] Step 4: The blast furnace smelts with the technical parameters of hot blast temperature of 1250 - 1350 °C and coal injection ratio of 190 - 220 kg / t·Fe, so as to improve the combustion efficiency of oxygen-enriched pulverized coal injection in the blast furnace.

[0016] According to the above scheme, in Step 1, the proportional relationship among the three materials of the raw materials charged into the furnace, the fuels charged into the furnace and the injection materials is 1.53 - 1.67 t: 0.27 - 0.34 t: 0.19 - 0.22 t.

[0017] According to the above scheme, in Step 1, the iron grade of the raw materials charged into the furnace is 60 - 65%, and the clinker ratio is 85 - 90%. The raw materials charged into the furnace include sinter, pellet and lump ore. Sinter and pellet are clinkers, and lump ore is raw ore, that is, the mass percentage of lump ore in the raw materials charged into the furnace is 10 - 15%. Further, the raw materials charged into the furnace are, by mass percentage: 70 - 75% of sinter, 10 - 20% of pellet, and 10 - 15% of lump ore. Among them, the sinter meets TFe 57 - 62%, R 1.70 - 1.85, the mass percentage of particles less than 5 mm is 0 - 5%, and the softening temperature range is 70 - 100 °C; the pellet meets TFe 63 - 68%, the compressive strength ≥ 2500 N / piece, and the softening temperature range is 60 - 110 °C; the lump ore meets TFe 63 - 68%, and the softening temperature range is 65 - 105 °C.

[0018] According to the above scheme, in Step 1, the mass ratio between the large coke and coke breeze is 27:2 - 64:7. It is required that the coke (i.e., the large coke and coke breeze) meets the requirements of moisture 0.2 - 0.4%, ash content 8 - 12.5%, M40 ≥ 85.00%, M10 ≤ 6.00%, CSR ≥ 68.00%, and CRI ≤ 26.00%.

[0019] According to the above scheme, in Step 1, by mass percentage, the bituminous coal ratio in the blast furnace injection material is 45 - 50%, the anthracite ratio is 46 - 49%, and the blast furnace slag ratio is 1 - 9%. The preparation method of the blast furnace injection material is as follows: The high-temperature molten blast furnace slag is naturally cooled to obtain the blast furnace slag; the blast furnace slag is mixed with the injection raw coal (i.e., anthracite and bituminous coal), and after grinding and pulverizing, a mixed powder is formed; among them, the mass percentage of particles with a particle size less than 0.075 mm in the mixed powder is greater than or equal to 80%.

[0020] According to the above solution, in step one, by mass percentage, the main components of blast furnace slag are: 32-34% of SiO2, 39-42% of CaO, 7-10% of MgO, 14-15% of Al2O3, 0.10-0.50% of FeO, 0.10-0.30% of MnO, 0.50-1.0% of TiO2, and inevitable impurities, etc.

[0021] According to the above solution, in step one, the volatile matter (V daf / % ) range of anthracite is 8-12%, and the fixed carbon (FC d ) range is 80-88%; the volatile matter (V daf / % ) range of bituminous coal is 25-40%, and the fixed carbon (FC d ) range is 62-70%; the volatile matter (V daf / % ) range of the mixed powder is 19-24%, and the fixed carbon (FC d ) ≥ 72%; among them, the volatile matter V daf of the mixed powder = volatile matter V daf of bituminous coal × bituminous coal ratio + volatile matter V daf of anthracite × anthracite ratio.

[0022] According to the above solution, the "inhibiting peripheral gas flow + developing central gas flow" burden distribution mode adopts a burden distribution matrix from the outer ring to the inner ring, and the charging matrix is: Or Or Where C is large coke, O is sinter + pellet + lump ore + coke breeze, the upper right number is the burden distribution angular position, and the lower right number is the burden distribution ring number corresponding to the upper right number.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] First of all, the present invention improves the blast furnace tuyere oxygen enrichment rate, increases the blast furnace output, uses a large proportion of high-volatile bituminous coal injection, increases the pulverized coal injection ratio into the furnace, and reduces the coke consumption; moreover, in order to deal with a large amount of unburned pulverized coal generated by increasing the pulverized coal injection amount, blast furnace slag is added to the pulverized coal injection, which improves the combustion performance of the pulverized coal and increases the combustion efficiency of the pulverized coal. This is because the pulverized coal combustion process is mainly controlled by the diffusion of oxygen. Adding a small amount of oxygen-containing blast furnace slag to the pulverized coal can increase the concentration of oxygen or oxidizing substances in the combustion zone, improve the oxygen supply conditions during pulverized coal combustion, promote pulverized coal combustion, thereby increasing the pulverized coal combustion rate, increasing the coal-coke replacement ratio, and reducing the blast furnace fuel ratio.

[0025] Second, the injection of anhydrous blast furnace slag in the present invention reduces the temperature of the tuyere raceway, replaces the humidified blast, reduces the possible condensation water volume in the blast furnace, reduces the erosion degree of the carbon bricks in the lower part of the hearth, and increases the blast furnace life.

[0026] Thirdly, blast furnace slag is a solid waste generated in blast furnace ironmaking with extremely low cost. In the present invention, blast furnace slag is used as an additive for pulverized coal injection. For blast furnaces with large pulverized coal injection amount and continuous production, the cost of combustion-supporting pulverized coal injection additive is reduced, and the production cost of oxygen-enriched blast furnace ironmaking is greatly reduced. Moreover, the use of blast furnace slag in the present invention plays a positive role in environmental protection. Detailed implementation manners

[0027] To better understand the present invention, the content of the present invention will be further clarified below in conjunction with embodiments, but the present invention is not limited to the following embodiments.

[0028] In the following embodiments, the ore batch is the raw materials charged into the blast furnace for each batch, excluding coke; the coke charged into the blast furnace for each batch is called the coke batch, and the sum of the ore batch and the coke batch is the combustion raw materials charged into the furnace for each batch.

[0029] Comparative example

[0030] A certain ironmaking plant with a volume of 3200 m 3 , prepares the raw materials for charging into the blast furnace, the fuels for charging into the furnace and the pulverized coal injection materials: for the raw materials charged into the furnace, there are 64.8 t of sinter ore per batch, 9.0 t of pellet ore per batch, and 16.2 t of lump ore per batch; the iron grade of the raw materials charged into the furnace is 59.8%, and the clinker rate is 82%; for the fuels charged into the furnace, there are 15.9 t of large coke and 2.1 t of coke breeze, and the pulverized coal injection amount of the blast furnace is 67 t / h;

[0031] Raw materials charged into the furnace: The TFe of the sinter ore is 58%, the basicity R is 1.90, the mass percentage of particles smaller than 5 mm is 6.5%, and the softening temperature range is 91 °C; the TFe of the pellet ore is 63%, the compressive strength is 2450 N / piece, and the softening temperature range is 105 °C; the TFe of the lump ore is 64%, and the softening temperature range is 62 °C; the moisture content of the coke charged into the furnace (large coke and coke breeze) is 0.5%, the ash content is 11.5%, M40 is 84.00%, M10 is 5.00%, CSR is 67.00%, and CRI is 27.00% by mass percentage;

[0032] The pulverized coal injection material of the blast furnace is bituminous coal + anthracite. Among them, by mass percentage: the proportion of bituminous coal is 47%, and the proportion of anthracite is 53%; the volatile content (V daf / % ) of bituminous coal is 35%, the volatile content (V daf / % ) of anthracite is 10%, and the volatile content (V daf / % ) of the mixed powder is 22%; the fixed carbon (FC d ) of bituminous coal is 60%, the fixed carbon (FC d ) of anthracite is 82%, and the fixed carbon (FC d ) of the mixed powder is 71.7%;

[0033] The blast furnace adopts a burden distribution mode of "restraining the peripheral gas flow + developing the central gas flow", specifically using a burden distribution matrix from the outer ring to the inner ring. The charging matrix is as follows: The charging matrix is: The mass percentage of the ore charged at the periphery is 25.0% of the ore batch. Here, C represents large coke, O represents sinter + pellet + lump ore + coke breeze, the upper right number is the charging angular position, and the lower right number is the charging ring number corresponding to the upper right number.

[0034] The oxygen enrichment rate adopted by the blast furnace is 9%, the inlet air area is 0.4260 m 2 , and the actual wind speed is 260 m / s.

[0035] The blast furnace smelts with technical parameters of hot blast temperature of 1250 °C, humidified blast volume of 3 g / m 3 , and coal injection ratio of 200 kg / t·Fe. After about 6 hours of smelting, the furnace charge is discharged through the taphole, and pig iron products with Si content of 0.25 - 0.80% are obtained.

[0036] During the smelting process, the daily output of the blast furnace is 9050 t, and the gas utilization efficiency is 48.5%. According to the consumption and output of the blast furnace, the fuel consumption per ton of iron is calculated. The coke ratio is 327 kg / t·Fe, and the fuel ratio is 527.0 kg / t·Fe.

[0037] Example 1

[0038] A method for improving the combustion efficiency of oxygen-enriched pulverized coal injection in a blast furnace, the specific process includes the following steps:

[0039] Step 1: For a 3200 m 3 blast furnace in a certain iron and steel plant, prepare the furnace charge, furnace fuel and injection materials: Each batch of sinter in the furnace charge is 63 t, each batch of pellet is 16.2 t, and each batch of lump ore is 10.8 t, that is, the ore batch is 90 t; The iron grade of the furnace charge is 60.1%, and the clinker ratio is 88%; The furnace fuel (coke batch 16.5 t) includes 15.3 t of large coke and 1.2 t of coke breeze, and the blast furnace injection material is 67 t / h.

[0040] Furnace charge: The TFe of sinter is 57.8%, R is 1.78, the mass percentage of particles less than 5 mm is 2%, and the softening temperature range is 82 °C; The TFe of pellet is 65%, the compressive strength is 2525 N / each, and the softening temperature range is 76 °C; The TFe of lump ore is 66%, and the softening temperature range is 71 °C.

[0041] Furnace fuel: The moisture content of the furnace coke (large coke and coke breeze) is 0.3%, the ash content is 11.5%, M40 is 87.00%, M10 is 3.00%, the hot strength CSR is 71.00%, and the hot reactivity CRI is 25.00%.

[0042] The blast furnace injection material is a mixed powder of bituminous coal + anthracite + blast furnace slag, and the preparation method is as follows: After the high-temperature molten blast furnace slag is naturally cooled, it is mixed with the injected raw coal (i.e., bituminous coal + anthracite), and ground to produce a mixed powder. The mass percentage of particles with a size below 0.075 mm is 82%; among them, by mass percentage: the proportion of bituminous coal is 48%, the proportion of anthracite is 49%, and the proportion of blast furnace slag is 3%; the volatile content (V daf / % ) of bituminous coal is 35%, the volatile content (V daf / % ) of anthracite is 10%, and the volatile content (V daf / % ) of the mixed powder is 22%; the fixed carbon (FC d ) of bituminous coal is 63%, the fixed carbon (FC d ) of anthracite is 87%, and the fixed carbon (FC d ) of the mixed powder is 72.9%; the mass percentage composition of blast furnace slag is SiO2 32%, CaO 40%, MgO 7.5%, Al2O3 14.2%, FeO 0.25%, MnO 0.15%, TiO2 0.58%, and others 5.32%;

[0043] Step 2: The blast furnace adopts a burden distribution mode of "suppressing the peripheral gas flow + developing the central gas flow", specifically using a burden distribution matrix from the outer ring to the inner ring. The charging matrix is: Among them, C is large coke, O is sinter + pellet + lump ore + coke breeze. The upper right number is the burden distribution angle position, and the lower right number is the burden distribution ring number corresponding to the upper right number. And it is controlled that the mass percentage of the ore burden distributed at the periphery is 35.7% of the ore batch;

[0044] Step 3: The oxygen enrichment rate adopted by the blast furnace is 11%, the inlet air area is 0.3859 m 2 , and the actual wind speed is 287 m / s;

[0045] Step 4: The blast furnace smelts with technical parameters of a hot blast temperature of 1250 °C, no humidified blast, and a coal injection ratio of 200 kg / t·Fe. The charged raw materials are discharged through the taphole after about 6 hours of smelting, and pig iron products with a Si content of 0.25 - 0.80% are obtained.

[0046] During the smelting process, the daily output of the blast furnace is 9521 t, and the gas utilization efficiency is 48.4%. According to the consumption and output of the blast furnace, the fuel consumption per ton of iron is calculated. The coke ratio is 316.4 kg / t·Fe, and the fuel ratio is 516.4 kg / t·Fe. The results show that compared with the comparative example, when the coal ratio remains unchanged at 200 kg / t·Fe, the gas utilization efficiency is close, and the proportion of blast furnace slag is 3%, the pulverized coal combustion rate is increased, the coke ratio is reduced by 10.6 kg / t·Fe, the coal-coke replacement ratio is increased, which proves that the combustion efficiency of the pulverized coal is improved, the fuel ratio is reduced by 2%, and the blast furnace production is increased by 5.2%.

[0047] Example 2

[0048] A method for improving the combustion efficiency of pulverized coal with oxygen enrichment in a blast furnace, and the specific process includes the following steps:

[0049] Step 1. For a certain iron-making plant with a volume of 3200 m 3 , prepare the raw materials, fuels and injection materials for the blast furnace: for each batch of raw materials charged into the furnace, there are 63 t of sinter, 14.4 t of pellet and 12.6 t of lump ore. The iron grade of the raw materials charged into the furnace is 61.6%, and the clinker ratio is 86%; for the fuels charged into the furnace, there are 14.6 t of large coke and 1.4 t of coke breeze, and the pulverized coal injection rate for the blast furnace is 67 t / h;

[0050] Raw materials charged into the furnace: The TFe of the sinter is 59.5%, R is 1.80, the mass percentage of particles less than 5 mm is 2.5%, and the softening temperature range is 95°C; the TFe of the pellet is 65%, the compressive strength is 2570 N / piece, and the softening temperature range is 69°C; the TFe of the lump ore is 68%, and the softening temperature range is 84°C; the moisture content of the coke (large coke and coke breeze) charged into the furnace is 0.31%, the ash content is 9.5%, M40 is 87.00%, M10 is 4.00%, CSR is 69.00%, and CRI is 24.00%;

[0051] The pulverized coal injection material for the blast furnace is a mixed powder of bituminous coal + anthracite + blast furnace slag. Among them, by mass percentage: the ratio of bituminous coal is 48%, the ratio of anthracite is 47%, and the ratio of blast furnace slag is 5%; the volatile matter (V daf / % ) of the bituminous coal is 31%, the volatile matter (V daf / % ) of the anthracite is 9%, and the volatile matter (V daf / % ) of the mixed powder is 19%; the fixed carbon (FC d ) of the bituminous coal is 65%, the fixed carbon (FC d ) of the anthracite is 87%, and the fixed carbon (FC d ) of the mixed powder is 72.1%; the mass percentage composition of the blast furnace slag is SiO2 34%, CaO 41%, MgO 8.3%, Al2O3 14.5%, FeO 0.30%, MnO 0.20%, TiO2 0.61%, and others 1.09%;

[0052] Step 2. The blast furnace adopts a burden distribution mode of "restraining the peripheral gas flow + developing the central gas flow", specifically using a burden distribution matrix from the outer ring to the inner ring. The charging matrix is: The charging matrix is: The mass percentage of the ore charged at the periphery is 33.3% of the ore batch. Among them, C is large coke, O is sinter + pellet + lump ore + coke breeze. The upper right number is the charging angular position, and the lower right number is the charging ring number corresponding to the upper right number;

[0053] Step 3: The oxygen enrichment rate adopted by the blast furnace is 12%, the air inlet area is 0.3900 m 2 , and the actual wind speed is 290 m / s;

[0054] Step 4: The blast furnace smelts with the technical parameters of hot blast temperature of 1250 °C, humidification blast volume of 0 g / m 3 , and coal injection ratio of 200 kg / t·Fe. After about 6 hours of smelting, the raw materials charged into the furnace are discharged through the iron notch, and pig iron products with Si content of 0.25 - 0.80% are obtained.

[0055] During the smelting process, the daily output of the blast furnace is 9783 t, and the gas utilization efficiency is 48.5%. According to the consumption and output of the blast furnace, the fuel consumption per ton of iron is calculated. The coke ratio is 311.7 kg / t·Fe, and the fuel ratio is 511.7 kg / t·Fe. The results show that compared with the comparative example, when the coal ratio remains unchanged at 200 kg / t·Fe, the gas utilization efficiency is close, and the blast furnace slag ratio is 5%, the pulverized coal combustion rate is increased, the coke ratio is reduced by 15.3 kg / t·Fe, the coal-coke replacement ratio is increased, the fuel ratio is reduced by 3%, and the blast furnace production is increased by 8.1%.

[0056] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the inventive concept of the present invention, several improvements and transformations can still be made, and these all belong to the protection scope of the present invention.

Claims

1. A method for improving the combustion efficiency of pulverized coal injected with oxygen enrichment in a blast furnace, characterized in that It includes the following steps: Step 1: Prepare the raw materials, fuels and injection materials for the blast furnace; among them, the raw materials for the blast furnace are sinter, pellet and lump ore, and the fuels for the blast furnace are large coke and coke breeze; the injection material for the blast furnace is a mixed powder of bituminous coal + anthracite + blast furnace slag. By mass percentage, the proportion of bituminous coal is 48-50%, the proportion of anthracite is 46-49%, and the proportion of blast furnace slag is 1-5%; by mass percentage, the main components of the blast furnace slag are: SiO2 32-34%, CaO 39-42%, MgO 7-10%, Al2O3 14-15%, FeO 0.1-0.5%, MnO 0.1-0.3%, TiO2 0.5-1.0%; Step 2: The blast furnace adopts a burden distribution mode of "suppressing the peripheral gas flow + developing the central gas flow", and the mass percentage of the ore burden distributed at the periphery is 33.3-35.7% of the ore batch; Step 3: The oxygen enrichment rate adopted by the blast furnace is 10-14%, and the inlet air area is adjusted according to the actual air volume of the blast furnace to control the actual wind speed at 285-300 m / s; Step 4: The blast furnace smelts with technical parameters of hot blast temperature of 1250-1350 °C and coal injection ratio of 190-220 kg / t·Fe to improve the combustion efficiency of oxygen-enriched pulverized coal injection in the blast furnace.

2. A method for improving the combustion efficiency of pulverized coal injected with oxygen enrichment in a blast furnace according to claim 1, characterized in that In Step 1, the iron grade of the raw materials charged into the furnace is 60-65%, and the clinker ratio is 85-90%.

3. A method for improving the combustion efficiency of pulverized coal injected with oxygen enrichment in a blast furnace according to claim 1, characterized in that The preparation method of the injection material for the blast furnace is: the high-temperature molten blast furnace slag is naturally cooled to obtain the blast furnace slag; the blast furnace slag is mixed with anthracite and bituminous coal and ground into a mixed powder; among them, the mass percentage of the particle size below 0.075 mm in the mixed powder is not less than 80%.

4. A method for improving the combustion efficiency of pulverized coal injected with oxygen enrichment in a blast furnace according to claim 1 or 3, characterized in that In Step 1, the volatile matter V of anthracite daf ranges from 8% to 12%, and the volatile matter V of bituminous coal daf ranges from 25% to 40%. The volatile matter V of the mixed powder daf ranges from 19% to 24%. Among them, the volatile matter V of the mixed powder daf = V of bituminous coal daf × proportion of bituminous coal + V of anthracite daf × proportion of anthracite.

5. A method for improving the combustion efficiency of pulverized coal injected with oxygen enrichment in a blast furnace according to claim 1, characterized in that In Step 2, the cloth distribution mode of "restraining the peripheral gas flow + developing the central gas flow" adopts a cloth matrix from the outer ring to the inner ring, and the charging matrix is as follows: Or Or , where C is large coke, O is sinter + pellet + lump ore + coke breeze, the upper right number is the cloth corner position, and the lower right number is the cloth ring number corresponding to the upper right number.

Images