Method for analyzing and modifying refractory structure of hydrogen-carbon-rich circulating oxygen blast furnace gas heating furnace

Abstract

The invention belongs to the technical field of gas heating furnace refractory material modification, and particularly discloses a hydrogen-rich carbon circulating oxygen blast furnace gas heating furnace refractory material structure analysis and modification method, which comprises the following steps: firstly, carrying out energy spectrum analysis and comparison on refractory materials before and after use, then analyzing the removal path of SiO2 and the reaction mechanism of Al2O3 in a reducing atmosphere, and calculating the content of the refractory materials; determining a substitute material of the refractory material in the upper high-temperature area; the refractory materials before and after use are subjected to XRD detection and comparison, then the used refractory materials are subjected to ash fusion point measurement, and the arrangement of the refractory material structure of the gas heating furnace is determined according to a temperature field distribution diagram of the gas heating furnace. By analyzing the refractory before and after use and modifying the refractory of the gas heating furnace, SiO2 and H2 are effectively prevented from reacting at high temperature to generate gaseous SiO to escape, lattice transformation is avoided, and the service life of the gas heating furnace is prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of refractory modification of gas heating furnaces, and in particular to a method for analyzing and modifying the refractory structure of a hydrogen-rich carbon circulating oxygen blast furnace gas heating furnace. Background Art

[0002] Through the technical research of hydrogen-rich carbon circulating oxygen blast furnace, in order to maintain the continuation of the blast furnace converter long process blast furnace technology, it is necessary to further increase the 400m 3 The hydrogen-rich carbon cycle oxygen blast furnace process was upgraded to 2500m 3 In the blast furnace, 2500m 3 The process of blast furnaces above 2500m 3 The hydrogen-rich carbon cycle oxygen blast furnace is used to achieve promotion value. At the same time, in order to maintain the 2500m 3 Basic structure and economic efficiency of hot blast stove for 2500m 3 The blast furnace was transformed into a 2500m 3 The hot blast furnace was upgraded to a gas heating furnace when the hydrogen-rich carbon circulating oxygen blast furnace was upgraded. After the gas heating furnace was upgraded, the process heating medium changed from the traditional blast furnace hot blast furnace heating cold air to the hydrogen-rich carbon circulating oxygen blast furnace process heating cold decarbonized coal gas.

[0003] In the existing technology, through 2500m 3 In the production practice of the gas heating furnace of the hydrogen-rich carbon cycle oxygen blast furnace, the difference between the dome pressure of the gas heating furnace and the pressure of the cold gas heating furnace at the bottom appeared, that is, the checker brick resistance increased, the amount of gas burning decreased, causing the furnace shell to turn red, and the gas heating temperature also dropped from 1200℃ to 950℃, which seriously affected the 2500m 3 The gas heating temperature, production stability and safe production of the first-class hydrogen-rich carbon circulating oxygen blast furnace gas heating furnace.

[0004] Therefore, it is necessary to study a method for analyzing and modifying the refractory structure of a hydrogen-rich carbon circulating oxygen blast furnace gas heating furnace to solve the problem that the increased resistance loss of the checker bricks causes the furnace shell to turn red, affecting the normal use of the hydrogen-rich carbon circulating oxygen blast furnace gas heating furnace and the production stability and safe production. Summary of the invention

[0005] The purpose of the present invention is to provide a method for analyzing and modifying the refractory structure of a hydrogen-rich carbon circulating oxygen blast furnace gas heating furnace, so as to solve the problem that the increased resistance loss of the checker bricks causes the furnace shell to turn red, affecting the normal use, production stability and safe production of the hydrogen-rich carbon circulating oxygen blast furnace gas heating furnace.

[0006] To achieve the above object, the basic scheme provided by the present invention is: a method for analyzing and modifying the refractory structure of a hydrogen-rich carbon circulating oxygen blast furnace gas heating furnace, comprising the following steps:

[0007] S1: First, take samples of the refractory before and after use, and then perform energy spectrum analysis and comparison on the refractory before and after use;

[0008] S2: Then analyze the main component of SiO2 in the gas heating furnace refractory in the CO-H2 coexistence system, the release path of SiO2 and the reaction mechanism of Al2O3 in the reducing atmosphere, and determine the alternative materials for the refractory in the upper high temperature zone;

[0009] S3: Then the staff conducted XRD tests and compared the refractory materials before and after use, and found that the crystal phase structure of SiO2 in the silicon bricks before and after burning had undergone a significant change, from tridymite to cristobalite;

[0010] S4: XRD test was performed on the damaged refractory material on the roof of the gas heating furnace. The test results showed that in addition to mullite, trace amounts of sillimanite and SiO5, calcium aluminum iron oxide silicate and elemental K and Fe were also detected;

[0011] S5: Then use the ash melting point tester to test the used refractory material. The results show that the white spots on the top surface of the used refractory material have turned dark brown, while the other five surfaces are still white. The upper part of the cross section has changed, while the lower part is still white. Since the temperature of the refractory material was not lowered to room temperature when the refractory material was sampled, the refractory material temperature was 200℃-300℃. When the refractory material was taken out, the surface of the refractory material was in a gelatinous glass phase. After tens of seconds, the surface morphology suddenly changed to a milky white solid.

[0012] S6: Further, according to the temperature field distribution diagram of the gas heating furnace under combustion and gas supply conditions, the influence of the changing law of the temperature field on the gas heating furnace and the changing law inside the furnace are clarified, so as to determine the layout of the refractory structure of the gas heating furnace.

[0013] The beneficial effects of the present invention are as follows: (1) the present invention can increase the gas temperature from 950°C to 1200°C, the through-porosity of the checker bricks after the transformation reaches 100%, and the pressure difference of the checker bricks after production is within 5 kPa; when the gas is heated to 1200°C, the gas temperature is increased by 250°C. According to the effective physical heat of the hot gas, which is 250°C×1.4×750=262.5MJ, the energy per kilogram of coke is 28MJ, and the gas temperature affects the coke ratio as follows: 262.5÷28=9.375kg; the loss is reduced by 9.375×1.8=16.875 yuan / t iron; (2) the lattice transformation of the bricks at the bottom of the furnace at 110-150°C is avoided, thereby extending the service life of the gas heating furnace.

[0014] Option 2 is the preferred basic option. In S1, through analysis, it is found that the main differences on both sides of the boundary are the differences in Si, Al, Ca, K and Mg elements. Elements such as Al, Ca, K and Mg are mainly concentrated in the low melting point phase area, and the distribution density of Si elements in the low melting point phase area is lower than that in the high melting point phase area; the shaded area shown by the Si element distribution is mainly occupied by Al and Ca, and K and Mg are also significantly higher than the Si-enriched area.

[0015] Scheme three is the preferred basic scheme. In S2, the initial generation temperature of SiO is about 1300℃ at 1 atm. As the pressure increases, the generation temperature of SiO increases, and it is still below 1500℃ at 5 atm. Therefore, it is concluded that the only way for SiO2 to escape at a high temperature of 1350℃ is to generate gaseous SiO, which does not react with Al2O3. Since corundum bricks have the characteristics of high temperature resistance and high aluminum content, they can be used as refractory materials for gas heating furnaces under reducing atmospheres. Therefore, it is determined that the silicon brick substitute material in the upper high-temperature zone is corundum bricks, and the refractory structure of the gas heating furnace under reducing atmospheres is further obtained.

[0016] Option 4 is the preferred basic option. In S5, the temperature did not drop to room temperature when the refractory material was sampled. The refractory material temperature was 200℃-300℃. When the refractory material was taken out, the surface of the refractory material was in a gelatinous glass phase. After tens of seconds, the surface morphology suddenly changed to a milky white solid. The crystalline structure of the siliceous lattice brick changed at high temperature, from tridymite to cristobalite. The cristobalite transformed at high temperature was β-cristobalite, which had a bluish-white gelatinous texture. As the temperature dropped, α-cristobalite was formed, which became a milky white opaque solid and the morphology seen.

[0017] Scheme 5 is the preferred basic scheme. In S6, the temperature of the decarbonized coal gas entering the gas heating furnace is 40°C, and the bottom temperatures of various refractory materials under the temperature gradient are 40°C, 60°C, 645°C, 775°C, 915°C, and 1265°C from bottom to top, respectively, and the temperature of the top layer of lattice bricks is 1295°C; after preheating the decarbonized coal gas with heat transfer oil, the bottom temperatures of various refractory materials under the temperature gradient are 150°C, 170°C, 705°C, 835°C, 975°C, and 1325°C from bottom to top, respectively, and the temperature of the top layer of lattice bricks is 1355°C; this forms the temperature field distribution of various refractory materials in the gas heating furnace, which is convenient for further determining the refractory materials used in each layer.

[0018] Scheme six is ​​the preferred basic scheme. In S6, according to the heating sequence of the gas heating furnace, the selection of the gas heating furnace from bottom to top is: low creep clay checker brick, clay checker brick, low creep clay checker brick, low creep high alumina checker brick, siliceous checker brick, corundum mullite checker brick; high alumina refractory materials are used in the top layer of the high temperature zone, which can effectively prevent SiO2 from reacting with H2 at high temperature to generate gaseous SiO and escape, thereby avoiding the silica brick reaction.

[0019] Option seven, this is the preferred basic option. In S6, according to the heating sequence of the gas heating furnace, the layer heights of each refractory material in the gas heating furnace are arranged from bottom to top as follows: 4 layers, 93 layers, 25 layers, 25 layers, 67 layers, and 5 layers, and the thickness of each refractory material is 120 mm; the interface of the siliceous checker brick is raised to 815°C before preheating or 925°C after preheating, which is away from the crystal phase transition point of the silica brick at 600°C. At the same time, the top arrangement of the siliceous checker brick has the characteristics of high temperature resistance and high strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a ternary phase diagram of SiO2-CaO-Al2O3 in a method for analyzing and modifying the refractory structure of a hydrogen-rich carbon cycle oxygen blast furnace gas heating furnace of the present invention;

[0021] Figure 2 It is a schematic diagram of a method for analyzing and modifying the refractory structure of a hydrogen-rich carbon cycle oxygen blast furnace gas heating furnace of the present invention, which reacts with SiO2 in a CO-H2 reducing atmosphere but does not react with Al2O3;

[0022] Figure 3 It is a schematic diagram of the temperature field distribution when the decarbonized coal gas is not preheated in a method for analyzing and modifying the refractory structure of a hydrogen-rich carbon circulating oxygen blast furnace coal gas heating furnace of the present invention;

[0023] Figure 4 It is a schematic diagram of the temperature field distribution during preheating of decarbonized coal gas in a method for analyzing and modifying the refractory structure of a hydrogen-rich carbon circulating oxygen blast furnace coal gas heating furnace of the present invention;

[0024] Figure 5 It is a schematic diagram of refractory selection for a gas heating furnace checker brick in a method for analyzing and modifying refractory structure of a hydrogen-rich carbon cycle oxygen blast furnace gas heating furnace of the present invention;

[0025] Figure 6 It is a schematic flow diagram of preheating of decarbonized coal gas in a method for analyzing and modifying the refractory structure of a hydrogen-rich carbon circulating oxygen blast furnace gas heating furnace of the present invention. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below through specific embodiments:

[0027] The figure marks in the drawings of the specification include: 1. decarbonization device; 2. flue gas heat exchanger; 3. decarbonization gas heater; 4. gas heating furnace; 5. decarbonization gas inlet valve; 6. flue gas outlet valve.

[0028] Example

[0029] like Figures 1 to 6 As shown, a method for analyzing and modifying the refractory structure of a hydrogen-rich carbon circulating oxygen blast furnace gas heating furnace comprises the following steps:

[0030] S1: First, the refractory materials before and after use are sampled, and then the energy spectrum analysis and comparison are performed on the refractory materials before and after use. Through analysis, it is found that the main differences on both sides of the boundary are the differences in Si, Al, Ca, K and Mg elements. Elements such as Al, Ca, K and Mg are mainly concentrated in the low melting point phase area, and the distribution density of Si elements in the low melting point phase area is lower than that in the high melting point phase area;

[0031] S2: Then analyze the main component of gas heating furnace refractory SiO2 in CO-H2 coexistence system, the release path of SiO2 and the reaction mechanism of Al2O3 in reducing atmosphere; it is concluded that the initial generation temperature of SiO is about 1300℃ at 1 atmosphere, and as the pressure increases, the temperature of SiO generation increases, and it is still lower than 1500℃ at 5 atmospheres, so it is concluded that the only way for SiO2 to escape at a high temperature of 1350℃ is to generate gaseous SiO, which does not react with Al2O3, thus determining that the alternative material for refractory in the upper high temperature zone is corundum brick;

[0032] S3: Then the staff conducted XRD tests and compared the refractory materials before and after use, and found that the crystal phase structure of SiO2 in the silicon bricks before and after burning had undergone a significant change, from tridymite to cristobalite;

[0033] S4: XRD test was performed on the damaged refractory material on the roof of the gas heating furnace. The test results showed that in addition to mullite, trace amounts of sillimanite and SiO5, calcium aluminum iron oxide silicate and elemental K and Fe were also detected;

[0034] S5: Then the ash melting point tester was used to test the used refractory material. The results showed that the white spots on the top surface of the used refractory material turned dark brown, while the other five surfaces were still white. The upper part of the cross section changed, while the lower part was still white.

[0035] S6: Further, according to the temperature field distribution diagram of the gas heating furnace under combustion and gas supply conditions, the influence of the change law of the temperature field on the gas heating furnace and the change law in the furnace are clarified; according to the temperature of the decarbonized gas entering the gas heating furnace is 40℃, the bottom temperatures of various refractory materials under the temperature gradient are 40℃, 60℃, 645℃, 775℃, 915℃, 1265℃ from bottom to top, and the temperature of the top checker brick is 1295℃; after the decarbonized gas is preheated by heat transfer oil, the temperature gradient of various refractory materials under the temperature gradient is The bottom layers of the refractory materials are 150°C, 170°C, 705°C, 835°C, 975°C and 1325°C from bottom to top, and the temperature of the top layer of checker bricks is 1355°C. According to the heating sequence of the above-mentioned gas heating furnace, the arrangement of the refractory structure of the gas heating furnace from bottom to top is determined as follows: 4 layers of low creep clay checker bricks, 93 layers of clay checker bricks, 25 layers of low creep clay checker bricks, 25 layers of low creep high alumina checker bricks, 67 layers of siliceous checker bricks and 5 layers of corundum mullite checker bricks.

[0036] After being put into use, in order to avoid Figure 5 The lattice transformation of 110℃-150℃ in the middle heating zone 1 is carried out, and the decarbonized coal gas is preheated by a heat transfer oil preheater. The heat transfer oil preheater is divided into an upper part and a lower part, the upper part is a decarbonized coal gas heater 3, and the lower part is a flue gas heat exchanger 2; the decarbonized coal gas treated by the decarbonization device 1 passes through the decarbonization coal gas heater 3, and is preheated to above 150℃ through heat exchange with the internal heat transfer oil pipe, and then is introduced into the gas heating furnace 4 in the heating period for heating, and is further heated to 850-1250℃ through the gas heating furnace, and finally introduced into the blast furnace. There are three gas heating furnaces, two of which are used for combustion and heat storage, and the other is used for heating; when storing heat, the decarbonized gas inlet valve 5 is closed, and the flue gas outlet valve 6 is opened to continuously provide hot flue gas to the flue gas heat exchanger 2, and then the hot flue gas enters the flue gas heat exchanger 2 to heat the heat transfer oil; when heating, the decarbonized gas inlet valve 5 is opened, the flue gas outlet valve 6 is closed, and the heat transfer oil heats the decarbonized gas in the decarbonized gas heater 3.

[0037] In summary, the refractory structure of the gas heating furnace is finally determined by the above-mentioned method of analyzing and modifying the refractory structure of the gas heating furnace; after being put into use, the decarbonized coal gas is preheated by a thermal oil preheater, and the decarbonized coal gas is preheated to above 150°C by heat exchange with the thermal oil preheater, and then heated in the gas heating furnace 4 to prevent SiO2 in the refractory from reacting with H2 at high temperature to generate gaseous SiO2 and escaping, thus avoiding Figure 5 The low creep clay checker bricks in the middle heating zone 1 undergo lattice transformation at 110°C-150°C, and the siliceous checker bricks in the heating zone 5 undergo lattice transformation at 600°C, thereby extending the service life of the gas heating furnace.

[0038] The above is only an embodiment of the present invention, and the common knowledge such as the known specific structure and characteristics in the scheme is not described in detail here. It should be pointed out that for those skilled in the art, several deformations and improvements can be made without departing from the structure of the present invention, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A method for analyzing and modifying the refractory structure of a hydrogen-rich carbon cycle oxygen blast furnace gas heating furnace, characterized in that: The following steps are involved: S1: First, take samples of the refractory before and after use, and then perform energy spectrum analysis and comparison on the refractory before and after use; S2: Then analyze the main component of SiO2 in the gas heating furnace refractory in the CO-H2 coexistence system, the release path of SiO2 and the reaction mechanism of Al2O3 in the reducing atmosphere, and determine the alternative materials for the refractory in the upper high temperature zone; S3: Then the staff conducted XRD tests and compared the refractory materials before and after use, and found that the crystal phase structure of SiO2 in the silicon bricks before and after burning had undergone a significant change, from tridymite to cristobalite; S4: XRD test was performed on the damaged refractory material on the roof of the gas heating furnace. The test results showed that in addition to mullite, trace amounts of sillimanite and SiO5, calcium aluminum iron oxide silicate and elemental K and Fe were also detected; S5: Then the ash melting point tester was used to test the used refractory material. The results showed that the white spots on the top surface of the used refractory material turned dark brown, while the other five surfaces were still white. The upper part of the cross section changed, while the lower part was still white. S6: Further, according to the temperature field distribution diagram of the gas heating furnace under combustion and gas supply conditions, the influence of the changing law of the temperature field on the gas heating furnace and the changing law inside the furnace are clarified, so as to determine the layout of the refractory structure of the gas heating furnace.

2. The method for analyzing and modifying the refractory structure of a hydrogen-rich carbon cycle oxygen blast furnace gas heating furnace according to claim 1 is characterized in that: In S1, analysis revealed that the main differences on both sides of the boundary are the differences in Si, Al, Ca, K and Mg elements. Elements such as Al, Ca, K and Mg are mainly concentrated in the low melting point phase region, and the distribution density of Si element in the low melting point phase region is lower than that in the high melting point phase region.

3. The method for analyzing and modifying the refractory structure of a hydrogen-rich carbon cycle oxygen blast furnace gas heating furnace according to claim 1 is characterized in that: In S2, the initial generation temperature of SiO at 1 atmosphere is about 1300℃. As the pressure increases, the generation temperature of SiO increases, but it is still below 1500℃ at 5 atmospheres. Therefore, it is concluded that the only way for SiO2 to escape at a high temperature of 1350℃ is to generate gaseous SiO without reacting with Al2O3.

4. The method for analyzing and modifying the refractory structure of a hydrogen-rich carbon cycle oxygen blast furnace gas heating furnace according to claim 1 is characterized in that: In S5, the temperature of the refractory material was not lowered to room temperature when the refractory material was sampled, and the temperature of the refractory material was 200°C-300°C. When the refractory material was taken out, the surface of the refractory material was in a gelatinous glass phase, and after tens of seconds, the surface morphology suddenly changed to a milky white solid.

5. The method for analyzing and modifying the refractory structure of a hydrogen-rich carbon cycle oxygen blast furnace gas heating furnace according to claim 1 is characterized in that: In S6, the temperature of the decarbonized coal gas entering the gas heating furnace is 40°C, and the bottom temperatures of various refractory materials under the temperature gradient are 40°C, 60°C, 645°C, 775°C, 915°C, and 1265°C from bottom to top, respectively, and the temperature of the top layer of lattice bricks is 1295°C; after the decarbonized coal gas is preheated by heat transfer oil, the bottom temperatures of various refractory materials under the temperature gradient are 150°C, 170°C, 705°C, 835°C, 975°C, and 1325°C from bottom to top, respectively, and the temperature of the top layer of lattice bricks is 1355°C.

6. The method for analyzing and modifying the refractory structure of a hydrogen-rich carbon cycle oxygen blast furnace gas heating furnace according to claim 1 is characterized in that: In S6, according to the heating sequence of the gas heating furnace, the selection of the gas heating furnace from bottom to top is: low creep clay checker brick, clay checker brick, low creep clay checker brick, low creep high alumina checker brick, siliceous checker brick, corundum mullite checker brick.

7. The method for analyzing and modifying the refractory structure of a hydrogen-rich carbon cycle oxygen blast furnace gas heating furnace according to claim 1 is characterized in that: In S6, according to the heating sequence of the gas heating furnace, the layer heights of each refractory material in the gas heating furnace are arranged from bottom to top as follows: 4 layers, 93 layers, 25 layers, 25 layers, 67 layers, and 5 layers, and the thickness of each refractory material is 120 mm.

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