A method for judging ring cracks of blast furnace carbon bricks

Abstract

The present invention is a device for judging whether blast furnace carbon bricks are ring-cracked, comprising: a box body, in which a refractory coating is arranged, and in which carbon bricks are suitable for being placed; a first temperature measuring thermocouple, whose temperature measuring end passes through the box body and is inserted into the cold surface of the carbon brick; a second temperature measuring thermocouple, whose temperature measuring end passes through the box body and is inserted into the hot surface of the carbon brick; a flame spray gun, which is inserted into the box body from the side of the box body and heats the hot surface of the carbon brick; an oxygen tank, which is connected to the flame spray gun and passes oxygen into the box body; in multiple temperature sections, the values ​​of the first temperature measuring thermocouple and the second temperature measuring thermocouple are collected, and then the heat flux intensity of the second carbon brick is obtained, and the heat flux intensity of the second carbon brick is compared with the heat flux intensity of the complete first carbon brick. If the value is less than 50%, the second carbon brick is a completely ring-cracked carbon brick; this method can accurately judge whether the blast furnace carbon bricks are ring-cracked.

Description

Technical Field

[0001] The invention relates to the field of blast furnaces, and in particular to a method for judging ring cracks of blast furnace carbon bricks. Background Art

[0002] With the continuous strengthening of blast furnace smelting in recent years, cracks are common in the carbon bricks of the furnace bottom and hearth during use. The formation of cracks will lead to the appearance of air gaps or cavities, and the thermal conductivity of air gaps or cavities is only 0.005W / m·K, which is only one thousandth of that of carbon bricks. This will reduce the heat dissipation capacity of the hearth, aggravate the erosion of the hearth, and reduce the life of the blast furnace. When the temperature of the carbon bricks is high, it is necessary to determine whether the air gap between the carbon bricks and the cooling wall in the furnace, the air gap between the cooling wall and the furnace shell, and the air gap caused by the ring crack of the carbon bricks in the furnace cause the temperature of the side wall of the hearth to rise. This is conducive to providing a basis for studying whether the carbon bricks in the hearth have ring cracks, providing necessary technical support for the next step of governance, and enriching the practical theory of blast furnace longevity.

[0003] At present, there are many different opinions on the causes of carbon brick ring cracks. Blast furnace production practice and theoretical research show that carbon brick ring cracks are related to factors such as carbon brick ash content, cracking, molten iron scouring, alkali metal and zinc corrosion, among which alkali metal and zinc corrosion are the main causes of ring cracks, but their corrosion mechanism is not very clear. In this regard, many scholars at home and abroad are still conducting a lot of research.

[0004] The blast furnace hearth is in a high-pressure, high-temperature working environment, with a temperature of up to 2000°C and a pressure of up to 3-4atm. In addition, blast furnace production is a fully closed, continuous, uninterrupted process, and the outside world can hardly directly observe the internal production situation.

[0005] At present, there are few methods for judging the ring crack of blast furnace carbon bricks, most of which are judged by manual experience and have low accuracy.

[0006] To this;

[0007] In summary, how to accurately judge whether blast furnace carbon bricks are ring cracked has become an urgent problem that researchers in this field need to solve. Summary of the invention

[0008] The technical problem to be solved by the present invention is: how to accurately judge whether the blast furnace carbon bricks are ring cracked

[0009] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0010] The present invention is a device for judging ring cracks of blast furnace carbon bricks, comprising: a box body, in which a refractory coating is arranged, and in which carbon bricks are suitable for being placed; a first temperature measuring thermocouple, whose temperature measuring end passes through the box body and is inserted into the cold surface of the carbon brick; a second temperature measuring thermocouple, whose temperature measuring end passes through the box body and is inserted into the hot surface of the carbon brick; a flame spray gun, which is inserted into the box body from the side of the box body and heats the hot surface of the carbon brick; an oxygen tank, which is connected to the flame spray gun and passes oxygen into the box body.

[0011] In order to illustrate a method for judging the ring cracking of blast furnace carbon bricks, the present invention comprises the following steps: S1: placing a complete first carbon brick into the box; S2: turning on the flame spray gun and the oxygen tank to heat the hot surface of the first carbon brick; S3: completing the heating of the first carbon brick for 10, 20, 30, 40, 50, and 60 minutes, and reading the values ​​of the first temperature measuring thermocouple and the second temperature measuring thermocouple respectively; S4: according to the heat flux intensity definition formula:

[0012] Q = λΔT / ΔS*100%;

[0013] Among them, Q-heat flux intensity of carbon brick, λ-thermal conductivity of carbon brick, ΔT-temperature difference at thermocouple detection point, ΔS-gradient at thermocouple detection point;

[0014] Q1, Q2, Q3, Q4, Q5 and Q6 are calculated; S5, after the box is cooled, the second carbon brick is placed into the box, and steps S2, S3 and S4 are repeated to calculate Q1', Q2', Q3', Q4', Q5'Q6'; S6, Q1 / Q1', Q2 / Q2', Q3 / Q3', Q4 / Q4', Q5 / Q5' and Q6 / Q6' to obtain 6 groups of values; S7: if one of the groups of values ​​is less than 50%, the second carbon brick is judged to be a completely ring-cracked carbon brick.

[0015] Furthermore, the first carbon brick and the second carbon brick have the same size.

[0016] Furthermore, the output flow rate of the oxygen tank is 6 to 8 m 3 / s.

[0017] The beneficial effects of the present invention: The present invention is a device for judging ring cracking of blast furnace carbon bricks and a judgment method thereof. In multiple temperature sections, the values ​​of a first temperature measuring thermocouple and a second temperature measuring thermocouple are collected to obtain the heat flux intensity of the second carbon brick. The heat flux intensity of the second carbon brick is compared with the heat flux intensity of the complete first carbon brick. If the value is less than 50%, the second carbon brick is a completely ring-cracked carbon brick. This method can accurately judge whether the blast furnace carbon bricks are ring-cracked. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0019] Figure 1 It is a schematic diagram of the present invention;

[0020] In the figure: 1. box body, 2. refractory coating, 3. carbon brick, 4. first temperature measuring thermocouple, 5. second temperature measuring thermocouple, 6. flame spray gun, 7. oxygen tank. DETAILED DESCRIPTION

[0021] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0022] Embodiment 1,

[0023] like Figure 1 As shown, the present invention is a device for judging ring crack of blast furnace carbon brick and a judgment method thereof, the outline of the complete first carbon brick is a rectangular parallelepiped, and its outer dimensions are 250mm×100mm×100mm;

[0024] Two through holes of φ10 mm are arranged at the bottom of the box body 1, and a first temperature measuring thermocouple 4 and a second temperature measuring thermocouple 5 are installed in the two through holes respectively; the thermocouples are installed at the above two positions to monitor the temperature of the carbon brick 3 in real time to ensure the temperature environment of the blast furnace is simulated, the first carbon brick ratio is reduced according to 10:1, and the flow rate in the oxygen pipe of the oxygen tank 7 is controlled to be 6-8m 3 / s, the flame spray gun 6 ignites oxygen to ensure that the hot surface temperature of the first carbon brick stabilizes at about 600°C after 40 minutes. It is found that after the hot surface of the first carbon brick is heated for 10, 20, 30, 40, 50, and 60 minutes, the hot surface temperature of the first carbon brick is measured by the second temperature measuring thermocouple 5 to be 185°C, 345°C, 475°C, 602°C, 632°C, and 605°C, and the hot surface temperature of the first carbon brick is measured by the first temperature measuring thermocouple 4 to be 73°C, 212°C, 356°C, 460°C, 482°C, and 474°C; and according to the length of the carbon brick and the thermal conductivity λ of the carbon brick is 20W / m·K (where λ is a constant), ΔS is the gradient of the thermocouple detection point, that is, the spacing between the first and second temperature measuring thermocouples is 250mm;

[0025] According to the formula Q = λΔT / ΔS*100%;

[0026] The calculated heat flux values ​​are Q1 8.96W, Q2 10.64W, Q3 9.52W, Q4 11.36W, Q5 12W, and Q6 10.48W;

[0027] After the box 1 is completely cooled, a second carbon brick of the same size and material is placed in the box 1, and the temperature environment of the blast furnace hearth is simulated again in the box 1 to heat the hot surface of the second carbon brick, and the flow rate in the oxygen pipe of the oxygen tank 7 is controlled to be 6-8m 3 / s, so that the second carbon brick sample is evenly heated, and it is found that after the hot surface of the second carbon brick is heated for 10, 20, 30, 40, 50, and 60 minutes, the hot surface temperature of the second carbon brick is measured by the second temperature measuring thermocouple 5 to be 189°C, 351°C, 508°C, 652°C, 724°C, and 840°C, and the hot surface temperature of the second carbon brick is measured by the first temperature measuring thermocouple 4 to be 64°C, 182°C, 330°C, 350°C, 270°C, and 224°C; and according to the length and The thermal conductivity λ of carbon brick is 20W / m·K. The calculation shows that the heat flux Q1' is 10.00W, Q2' 13.52W, Q3' 14.24W, Q4' 24.16W, Q5' 36.32W and Q6' 49.28W. The ratios of heat flux Qn / Qn' of carbon bricks of the first and second samples are 89.60%, 78.70%, 66.85%, 47.02%, 33.04% and 21.27% respectively.

[0028] The experimental results are analyzed to determine the basis for the formation of ring cracks in the second carbon brick: (1) When the second carbon brick is broken due to thermal stress, there is no other filler in the middle of the crack, and the thermal stress is released quickly after the fracture is formed. This is the direct reason for the sharp rise in the temperature of the hot surface of the carbon brick ring crack; (2) From the above data analysis, it can be concluded that after heating the second carbon brick for 40 minutes, the ratio of the heat flux intensity Q4 / Q4' of the carbon brick is 47.02%<50%, so the carbon brick can be regarded as a completely ring cracked state; that is, as long as Qn / Qn'<50%, the second carbon brick can be regarded as a completely ring cracked state.

[0029] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A method for determining ring cracking of blast furnace carbon bricks, the device comprising: a box body, in which a refractory coating is provided and in which carbon bricks are suitable for being placed; A first temperature measuring thermocouple, whose temperature measuring end passes through the box and is inserted into the cold surface of the carbon brick; a second temperature measuring thermocouple, whose temperature measuring end passes through the box and is inserted into the hot surface of the carbon brick; a flame spray gun, which is inserted into the box from the side of the box and heats the hot surface of the carbon brick; an oxygen tank, which is connected to the flame spray gun and passes oxygen into the box; It is characterized by comprising the following steps: S1: placing a complete first carbon brick into the box; S2: Turn on the flame spray gun and oxygen tank to heat the hot surface of the first carbon brick; S3: heating the first carbon brick for 10, 20, 30, 40, 50, and 60 minutes, and reading the values ​​of the first temperature measuring thermocouple and the second temperature measuring thermocouple respectively; S4: According to the definition of heat flux intensity: Q = λΔT / ΔS*100%; Among them, Q-heat flux intensity of carbon brick, λ-thermal conductivity of carbon brick, ΔT-temperature difference at thermocouple detection point, ΔS-gradient at thermocouple detection point; Q1, Q2, Q3, Q4, Q5, Q6 are calculated; S5. After the box is cooled, put the second carbon brick into the box, and repeat steps S2, S3, and S4 to calculate Q1', Q2', Q3', Q4', Q5', and Q6'; S6, Q1 / Q1', Q2 / Q2', Q3 / Q3', Q4 / Q4', Q5 / Q5', Q6 / Q6', to obtain 6 sets of values; S7: If one of the sets of values ​​is less than 50%, the second carbon brick is judged to be a completely ring-cracked carbon brick.

2. The method for judging ring crack of blast furnace carbon bricks according to claim 1, characterized in that: The first carbon brick and the second carbon brick have the same size.

3. The method for judging ring crack of blast furnace carbon bricks according to claim 2, characterized in that: The output flow rate of the oxygen tank is 6-8m 3 / s.

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