Gas injection method in limonite sintering process

Abstract

The invention discloses a coal gas injection method in a limonite sintering process, which comprises the following steps of: integrally imaging a sintering charge level according to a thermal imager above the charge level of a sintering machine to obtain the predicted temperature of the charge level, and dividing the charge level into a preheating area, a low-temperature reaction area, a medium-temperature reaction area, a high-temperature sintering area and a cooling area according to the predicted temperature of the charge level; blowing coal gas and mist water drops to the preheating area, the low-temperature reaction area, the medium-temperature reaction area, the high-temperature sintering area and the cooling area according to the coal gas injection amount and pressure and the mist water drop injection amount and pressure of the corresponding areas, and sintering; local overheating or supercooling can be avoided, and the sintering quality is powerfully guaranteed; the gas permeability of a material layer can be optimized through partitioned injection of water vapor, gas circulation and reaction development are facilitated, according to different sintering stages, coal gas and fog drop water are injected at a certain flow rate and pressure, various working conditions can be well adapted, solid fuel consumption in the sintering process is reduced, and the sintered ore yield is increased.

Description

Technical Field

[0001] The invention belongs to the field of ironmaking, and in particular relates to a coal gas injection method in a limonite sintering process. Background Art

[0002] In the field of raw materials for the steel industry, limonite occupies an important position. However, its own characteristics bring many challenges to processing. Limonite usually contains more crystal water. During the sintering process, the decomposition of crystal water requires a lot of heat, which not only increases energy consumption, but also easily leads to uneven heat distribution. The structural particles of limonite are fine and the air permeability is poor, making it difficult for air and combustion gases to flow smoothly in the material layer. During sintering, this will hinder heat transfer, affect the rate and degree of chemical reaction, and make it difficult to form high-quality sintered ore. In the prior art, coal gas is directly sprayed onto the material surface. Due to the particularity of limonite, the sintering process has fine requirements on conditions such as heat atmosphere, which does not have the particularity for limonite. Excessive coal gas injection will also cause a waste of resources.

[0003] Patent CN201810262280.1 discloses a gas injection device and injection method for a sintering machine. The vertically arranged gas injection device can only evenly inject the sintered ore on the entire sintering machine trolley to improve the quality of the sintered ore. Differentiated supply according to the heat demand of different parts may lead to an oversupply of gas in some areas and insufficient gas supply in some areas, and the energy utilization efficiency is relatively low. Patent CN201610749468.X discloses a multi-row synchronous rotating injection device and injection method for auxiliary sintering. The rotating airflow is formed by rotating the blocked pipe, and the design of multiple rows of gas blowing pipes and multiple blowing pipe blowing holes is combined to allow the gas to mix evenly with the atmosphere, effectively improving the sintering efficiency. Due to the blocking pipe structure and the multi-row coordination problem, this patent has local uneven injection, which will cause excessive local temperature, excessive liquid phase production and bonding of the material layer, and worsen the permeability of the material layer. Summary of the invention

[0004] The purpose of the present invention is to provide a method for gas injection in the process of limonite sintering, so as to increase the utilization ratio of limonite in sintering and reduce the solid fuel consumption of sintering.

[0005] The present invention adopts the following technical scheme: a method for gas injection in the sintering process of limonite, wherein a thermal imager above the material surface of the sintering machine is used to image the sintering material surface as a whole, and the predicted temperature of the material surface is obtained, and the material surface is divided into a preheating zone, a low-temperature reaction zone, a medium-temperature reaction zone, a high-temperature sintering zone, and a cooling zone according to the predicted temperature of the material surface;

[0006] Coal gas and mist water are blown into the preheating zone, low-temperature reaction zone, medium-temperature reaction zone, high-temperature sintering zone and cooling zone according to the gas injection amount and pressure and mist water injection amount and pressure of the corresponding areas, and sintering is carried out.

[0007] Furthermore, when mixing the sintering materials, the proportion of limonite with a particle size of 3-5 mm is more than 65%, and the calorific value of the coal gas during the sintering process is 5500-8000 kJ / m 3 , the exhaust negative pressure is 7-15kPa, and the particle size of the droplet water particles is 100-300μm.

[0008] Furthermore, the temperature range of the preheating zone is 1000-1200°C; the gas injection flow rate of the preheating zone is 600-800m 3 / h, gas injection pressure is 30-45kPa; droplet water injection flow rate is 2-5m 3 / h, the spray pressure of droplet water is 15-20kPa.

[0009] Furthermore, the temperature range of the low temperature reaction zone is 1201-1300°C.

[0010] Furthermore, the gas injection flow rate in the low temperature reaction zone is 200-400m 3 / h, the gas injection pressure is 15-25kPa.

[0011] Furthermore, the temperature range of the medium temperature reaction zone is 1301-1350°C.

[0012] Furthermore, the gas injection flow rate in the medium temperature reaction zone is 50-180m 3 / h, the gas injection pressure is 10-15kPa.

[0013] Furthermore, the temperature range of the high temperature sintering zone is 1351-1400°C.

[0014] Furthermore, the spray flow rate of the mist water in the high temperature sintering zone is 1-1.5m 3 / h, the spray pressure of droplet water is 5-10kPa.

[0015] Furthermore, the temperature of the cooling zone is less than 1000°C, and the spray flow rate of the mist water is 0.2-0.5m 3 / h, the spray pressure of droplet water is 2-5kPa.

[0016] The beneficial effects of the present invention are:

[0017] The present invention divides the material surface of the sintering process into zones according to the material surface temperature, and sprays coal gas and mist water at a certain flow rate and pressure above different sintering machine areas. The coal gas is mixed with the air more evenly and fully through the zones, and local overheating or overcooling is avoided, which effectively guarantees the sintering quality. The zoned spraying of water vapor can optimize the air permeability of the material layer, which is beneficial to gas circulation and reaction. In addition, the spraying of coal gas and mist water at a certain flow rate and pressure according to different sintering stages can well adapt to various working conditions, reduce the solid fuel consumption in the sintering process, and improve the sintered ore yield.

[0018] In terms of combustion characteristics, limonite has a high content of crystalline water and a large burn loss, and it is difficult for traditional sintering fuel combustion to provide stable and sufficient heat. The present invention can use segmented gas injection to accurately control the heat input at each stage and compensate for the heat demand characteristics of limonite. For atmosphere control, gas injection can create a reducing atmosphere, promote the reduction of high-valent iron oxides in limonite, improve its sintering performance, and enable it to still sinter well at a higher ratio. From the perspective of heat transfer and utilization, segmented injection optimizes the temperature distribution in the material layer and reduces heat loss. Limonite can make full use of heat to complete complex physical and chemical changes, thereby increasing its proportion in the mixture, which is beneficial to improving the quality of sintered ore and controlling costs. DETAILED DESCRIPTION

[0019] The present invention is described in detail below in conjunction with specific implementation modes.

[0020] The invention discloses a method for gas injection in the sintering process of limonite, wherein a thermal imager above the material surface of a sintering machine is used to image the sintering material surface as a whole, and a predicted temperature of the material surface is obtained. The material surface is divided into a preheating zone, a low-temperature reaction zone, a medium-temperature reaction zone, a high-temperature sintering zone, and a cooling zone according to the predicted temperature of the material surface;

[0021] Coal gas and mist water are blown into the preheating zone, low-temperature reaction zone, medium-temperature reaction zone, high-temperature sintering zone and cooling zone according to the gas injection amount and pressure and mist water injection amount and pressure of the corresponding areas, and sintering is carried out.

[0022] Among them, the proportion of limonite with a particle size of 3-5mm in the sintering material is more than 65%, and the calorific value of coal gas during the sintering process is 5500-8000kJ / m 3 , the exhaust negative pressure is 7-15kPa, and the particle size of the droplet water particles is 100-300μm.

[0023] The temperature range of the preheating zone is 1000-1200℃; the gas injection flow rate of the preheating zone is 600-800m 3 / h, gas injection pressure is 30-45kPa; droplet water injection flow rate is 2-5m 3 / h, the spray pressure of droplet water is 15-20kPa.

[0024] The temperature range of the low temperature reaction zone is 1201-1300°C. The gas injection flow rate of the low temperature reaction zone is 200-400m 3 / h, the gas injection pressure is 15-25kPa.

[0025] The temperature range of the medium temperature reaction zone is 1301-1350°C. The gas injection flow rate of the medium temperature reaction zone is 50-180m 3 / h, the gas injection pressure is 10-15kPa.

[0026] The temperature range of the high temperature sintering zone is 1351-1400℃. The spray flow rate of the high temperature sintering zone is 1-1.5m 3 / h, the spray pressure of droplet water is 5-10kPa.

[0027] The temperature of the cooling zone is less than 1000℃, and the spray flow rate of the mist water is 0.2-0.5m 3 / h, the spray pressure of droplet water is 2-5kPa.

[0028] If the mist water flow rate in the preheating zone is too large, it will reduce the initial sintering effect. The mist water flow rate in the high-temperature sintering zone can improve the air permeability of the sintered ore and promote the oxidation reaction. However, if the flow rate is too high, it may cause over-humidification and reduce the strength of the sintered ore.

[0029] The sintered ore in the cooling zone has been basically formed. If the mist water flow is too large, the sintered ore will be over-moistened, and then too much water will enter the sintered ore. Internal stress may be generated during the cooling process, resulting in defects such as cracks in the sintered ore, reducing the strength of the sintered ore. Therefore, appropriate pressure is the key to ensure that the mist droplets are evenly distributed in different areas above the sintering machine. The distance from the nozzle to the sintering bed in different areas is different. By controlling the pressure, the mist droplets can achieve an ideal coverage range in each area.

[0030] Example 1

[0031] In the sintering agglomeration method of limonite in this embodiment, the proportion of limonite with a particle size of 3-5 mm in the sintering material is 65%, and the calorific value of the coal gas is 5500 J / m 3 , the negative pressure of exhaust is 7kPa. The particle size of mist droplets is 300μm.

[0032] Preheating zone: gas injection flow rate is 600m 3 / h, gas injection pressure is 30kPa. Mist water injection flow rate is 2m 3 / h, the spray pressure of droplet water is 15kPa.

[0033] Low temperature reaction zone: gas injection flow rate is 200m 3 / h, the gas injection pressure is 15kpa.

[0034] Medium temperature reaction zone: gas injection flow rate is 50m 3 / h, the gas injection pressure is 10kPa.

[0035] High temperature sintering area: the spray flow rate of water droplets is 1m 3 / h, the droplet water spraying pressure is 5kPa.

[0036] Cooling area: mist water spray flow rate is 0.2m 3 / h, the spray pressure of droplet water is 2kPa.

[0037] According to calculation, the sintering solid fuel consumption is 56.4kg / t and the yield is 74.2%.

[0038] Example 2

[0039] In the sintering agglomeration method of limonite in this embodiment, the proportion of limonite with a particle size of 3-5 mm in the sintering material is 67.4%, and the calorific value of the coal gas is 5764 kJ / m 3 The negative pressure of the exhaust is 14.5kPa, and the particle size of the droplet water is 294μm.

[0040] Preheating zone: gas injection flow rate is 643m 3 / h, the gas injection pressure is 31.5kPa. The spray flow rate of the mist water is 2.43m 3 / h, the droplet water spraying pressure is 16.2kPa.

[0041] Low temperature reaction zone: gas injection flow rate is 217m 3 / h, the gas injection pressure is 16.5kPa.

[0042] Medium temperature reaction zone: gas injection flow rate is 64.2m 3 / h, the gas injection pressure is 11.4kPa.

[0043] High temperature sintering area: the spray flow rate of water droplets is 1.05m 3 / h, the droplet water spraying pressure is 5.4kPa.

[0044] Cooling area: mist water spray flow rate is 0.25m 3 / h, the droplet water spraying pressure is 2.4kPa.

[0045] According to calculation, the sintering solid fuel consumption is 54.5kg / t and the yield is 76.4%.

[0046] Example 3

[0047] In the sintering agglomeration method of limonite in this embodiment, the proportion of limonite with a particle size of 3-5 mm in the sintering material is 71.6%, and the calorific value of the coal gas is 6385 kJ / m 3 The negative pressure of the exhaust is 12.5kPa. The particle size of the mist droplets is 216μm.

[0048] Preheating zone: gas injection flow rate is 707m 3 / h, the gas injection pressure is 36.3kPa, and the droplet water injection flow rate is 3.41m 3 / h, the droplet water spraying pressure is 17.6kPa.

[0049] Low temperature reaction zone: gas injection flow rate is 284m 3 / h, the gas injection pressure is 19.7kPa.

[0050] Medium temperature reaction zone: gas injection flow rate is 83.1m 3 / h, the gas injection pressure is 14.4kPa.

[0051] High temperature sintering area: the spray flow rate of water droplets is 1.31m 3 / h, the droplet water spraying pressure is 6.2kPa.

[0052] Cooling area: the spray flow rate of mist water is 0.36m 3 / h, the droplet water spraying pressure is 3.1kPa.

[0053] According to calculation, the sintering solid fuel consumption is 53.4kg / t and the yield is 79.6%.

[0054] Example 4

[0055] In the sintering agglomeration method of limonite in this embodiment, the proportion of limonite with a particle size of 3-5 mm in the sintering material is 75.3%, and the calorific value of the coal gas is 7054 kJ / m 3 The negative pressure of the exhaust is 10.6 kPa. The particle size of the mist droplets is 124 μm.

[0056] Preheating zone: gas injection flow rate is 754m 3 / h, the gas injection pressure is 39.2kPa, and the droplet water injection flow rate is 3.34m 3 / h, the droplet water spraying pressure is 18.6kPa.

[0057] Low temperature reaction zone: gas injection flow rate is 309m 3 / h, the gas injection pressure is 22.4kPa.

[0058] Medium temperature reaction zone: gas injection flow rate is 93.2m 3 / h, the gas injection pressure is 13.1kPa.

[0059] High temperature sintering area: the spray flow rate of water droplets is 1.42m 3 / h, the droplet water spraying pressure is 7.6kPa.

[0060] Cooling area: the mist flow rate is 0.41m 3 / h, the droplet water spraying pressure is 3.6kPa.

[0061] According to calculation, the sintering solid fuel consumption is 52.6kg / t and the yield is 81.3%.

[0062] Example 5

[0063] In the sintering agglomeration method of limonite in this embodiment, the proportion of limonite with a particle size of 3-5 mm in the sintering material is 84.2%, and the calorific value of the coal gas is 8000 J / m 3 The negative pressure of the exhaust is 15kPa. The particle size of the mist droplets is 100μm.

[0064] Preheating zone: gas injection flow rate is 800m 3 / h, the gas injection pressure is 45kPa, and the droplet water injection flow rate is 5m 3 / h, the spray pressure of droplet water is 20kPa.

[0065] Low temperature reaction zone: gas injection flow rate is 400m 3 / h, the gas injection pressure is 25kPa.

[0066] Medium temperature reaction zone: gas injection flow rate is 180m 3 / h, the gas injection pressure is 15kPa.

[0067] High temperature sintering area: the spray flow rate of water droplets is 1.5m 3 / h, the gas injection pressure is 10kPa.

[0068] Cooling area: mist water spray flow rate is 0.5m 3 / h, the droplet water spraying pressure is 5kPa.

[0069] According to calculation, the sintering solid fuel consumption is 50.4kg / t and the yield is 83.5%.

[0070] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for gas injection in a sintering process of limonite, characterized in that: The thermal imager above the sintering machine material surface is used to image the sintering material surface as a whole to obtain the predicted temperature of the material surface. The material surface is divided into a preheating zone, a low-temperature reaction zone, a medium-temperature reaction zone, a high-temperature sintering zone, and a cooling zone according to the predicted temperature of the material surface. The preheating zone, low-temperature reaction zone, medium-temperature reaction zone, high-temperature sintering zone and cooling zone are blown with coal gas and mist water according to the coal gas blowing amount and pressure and mist water blowing amount and pressure of the corresponding areas, and sintering is carried out.

2. The method for gas injection in a limonite sintering process according to claim 1, characterized in that: When mixing the sintering materials, the proportion of limonite with a particle size of 3-5 mm is more than 65%, and the calorific value of the coal gas during the sintering process is 5500-8000 kJ / m 3 , the exhaust negative pressure is 7-15kPa, and the particle size of the droplet water particles is 100-300μm.

3. The method for gas injection in a limonite sintering process according to claim 2, characterized in that: The temperature range of the preheating zone is 1000-1200°C; the gas injection flow rate of the preheating zone is 600-800m 3 / h, gas injection pressure is 30-45kPa; droplet water injection flow rate is 2-5m 3 / h, the spray pressure of droplet water is 15-20kPa.

4. The method for gas injection in a limonite sintering process according to claim 1, characterized in that: The temperature range of the low temperature reaction zone is 1201-1300°C.

5. The method for gas injection in a limonite sintering process according to claim 4, characterized in that: The gas injection flow rate in the low temperature reaction zone is 200-400m 3 / h, the gas injection pressure is 15-25kPa.

6. The method for gas injection in a limonite sintering process according to claim 1, characterized in that: The temperature range of the medium temperature reaction zone is 1301-1350°C.

7. The method for gas injection in a limonite sintering process according to claim 6, characterized in that: The gas injection flow rate in the medium temperature reaction zone is 50-180m 3 / h, the gas injection pressure is 10-15kPa.

8. The method for gas injection in a limonite sintering process according to claim 1, characterized in that: The temperature range of the high temperature sintering zone is 1351-1400°C.

9. The method for gas injection in a limonite sintering process according to claim 8, characterized in that: The spray flow rate of the mist water in the high temperature sintering zone is 1-1.5m 3 / h, the spray pressure of droplet water is 5-10kPa.

10. The method for gas injection in a limonite sintering process according to claim 1, characterized in that: The temperature of the cooling zone is less than 1000°C, and the spray flow rate of the mist water is 0.2-0.5m 3 / h, the spray pressure of droplet water is 2-5kPa.