Fire-resistant structure of hydrogen-rich carbon circulating oxygen blast furnace gas heating furnace and determination method of fire-resistant structure

Abstract

The invention belongs to the technical field of type selection of refractory materials of heating furnaces, and particularly discloses a refractory structure of a hydrogen-carbon-rich circulating oxygen blast furnace gas heating furnace and a method for determining the refractory structure. The refractory structure is formed by sequentially building low-creep clay checker bricks, clay checker bricks, low-creep clay checker bricks, low-creep high-aluminum checker bricks, siliceous checker bricks and corundum mullite checker bricks from bottom to top. In order to solve the problem that a furnace body is damaged and collapsed due to weight loss of a refractory material in a heating furnace under reductive CO and H2, SiO2 and H2 are prevented from high-temperature reaction to generate gaseous SiO which escapes in a manner of selecting a more efficient and safer refractory material of the heating furnace, so that silica brick reaction is avoided, and the problem that when a gas heating furnace heats decarburized gas, the decarburized gas cannot be heated by the gas heating furnace is solved. The problem that high-reducibility CO and H2 in decarburized coal gas react with a refractory material in a coal gas heating furnace in a high-temperature environment, so that the refractory material is damaged and loses efficacy, and finally the coal gas heating furnace cannot normally heat coal gas is solved.

Description

Technical Field

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

[0002] The medium heated by the hydrogen-rich carbon cycle oxygen blast furnace gas heating furnace is decarbonized coal gas or even hydrogen-rich decarbonized coal gas, which can provide 1200℃ high-pressure injection coal gas for the hydrogen-rich carbon cycle oxygen blast furnace. At present, the gas heating furnace is built from bottom to top with low creep clay checker bricks, clay checker bricks, low creep clay checker bricks and silica checker bricks, and the number of layers of each checker brick is 4 layers, 106 layers, 25 layers and 84 layers respectively. Under this refractory structure, when the gas heating furnace is used to heat the injection coal gas, due to the large amount of SiO2 contained in the silica bricks, the SiO2+H2=SiO(g)↑+H2O reaction will occur at high temperature, causing the refractory material to fail. Checker bricks will also have problems of weight loss and strength attenuation under long-term use, which greatly affects the stability and safety of the checker bricks in the high-temperature area of ​​the arch, causing the furnace skin of the gas heating furnace in the low-creep clay checker brick section to turn red, and even causing safety hazards such as furnace body collapse, ultimately causing the gas heating furnace to be unable to heat the gas normally.

[0003] Therefore, in order to extend the service life of the refractory materials of the hydrogen-rich carbon cycle oxygen blast furnace gas heating furnace, it is necessary to design a refractory structure of the hydrogen-rich carbon cycle oxygen blast furnace gas heating furnace and a method for determining the refractory structure. The present invention adopts refractory materials and refractory structures that are more suitable for hydrogen-rich carbon cycle oxygen blast furnace gas heating furnaces to solve the problem that the reducing CO and H2 react with the refractory materials in the heating furnace at high temperature, causing damage and failure of the refractory materials. Summary of the invention

[0004] The purpose of the present invention is to provide a refractory structure of a hydrogen-rich carbon circulating oxygen blast furnace gas heating furnace and a method for determining the refractory structure, so as to solve the problem that when the gas heating furnace heats decarbonized gas, the highly reducing CO and H2 in the decarbonized gas react with the refractory materials in the gas heating furnace under a high temperature environment, causing the refractory materials to be damaged and fail, and ultimately resulting in the gas heating furnace being unable to heat the gas normally.

[0005] To achieve the above object, the basic scheme provided by the present invention is: a method for determining the refractory structure of a hydrogen-rich carbon cycle oxygen blast furnace gas heating furnace, characterized in that it comprises the following steps:

[0006] S1: When selecting refractory materials for gas heating furnaces, the staff will first take samples of the used refractory materials and perform chemical composition analysis;

[0007] S2: The staff will conduct XRD test on the refractory materials before and after use;

[0008] S3: Then, based on thermodynamics, we can infer the release path of SiO2 and the reaction mechanism of Al2O3 in a reducing atmosphere after the reducing CO and H2 react with the refractory material at high temperature;

[0009] S4: Determine the replacement material for the silicon refractory material in the high temperature zone of the gas heating furnace according to the result of the SiO2 escape path;

[0010] S5: Determine the masonry height of each refractory material in the gas heating furnace according to the temperature field distribution diagram;

[0011] S6: Finally, the operator will carry out on-site construction preparation and refractory masonry.

[0012] The beneficial effects of the present invention are as follows: (1) the present invention not only reduces the cost, but also effectively prevents SiO2 and H2 from reacting at high temperature to generate gaseous SiO and escaping, avoids the reaction of silicon bricks, thereby preventing the refractory material from being damaged and causing failure, and prolongs the service life of the gas heating furnace; (2) after the refractory material of the gas heating furnace is modified, the through-porosity rate of the checker brick is 100%, and the pressure difference of the checker brick is within 5KPa after being put into production. The furnace shell temperature below the surface of the refractory material of the gas heating furnace is less than 80°C. Through the reselection and optimization of the refractory material, the gas heating furnace's burning and gas delivery functions are enhanced, achieving long-term stability while reducing the solid fuel ratio.

[0013] Scheme 2 is the preferred basic scheme. In S1, the SiO2 content of the refractory material before use is 95.102wt%, the CaO content is 2.585wt%, the Fe2O3 content is 0.842wt%, the Al2O3 content is 0.508wt%, and the K2O content is 0.148wt%. The SiO2 content of the refractory material after use is 91.954wt%, the CaO content is 0.552wt%, the Fe2O3 content is 0.184wt%, the Al2O3 content is 1.331wt%, and the K2O content is 0.26wt%; the SiO2, CaO and Fe2O3 contents in the refractory material after use are reduced compared with those in the refractory material before use, while the Al2O3 and K2O contents are increased compared with those in the refractory material before use.

[0014] Option three is the preferred basic option. In S3, the temperature at which SiO2 is reduced to SiO in the CO-H2 coexistence system is 1300℃-1500℃, and it does not react with Al2O3. The chemical reactions that may occur in the gas heating furnace under a high-temperature and high-reducing atmosphere are determined, and it is found that under hydrogen-rich smelting conditions, the chemical corrosion of high-temperature hydrogen on siliceous refractory materials is more serious, thereby determining alternative materials for siliceous refractory materials in the high-temperature zone.

[0015] Option 4 is the preferred basic option. In S5, the temperature field is divided into a low-temperature section, a medium-temperature section and a high-temperature section. The temperature of the low-temperature section is ≤500°C, the temperature of the medium-temperature section is: 500°C < medium-temperature section temperature <800°C, and the temperature of the high-temperature section is: 800°C ≤ high-temperature section temperature <1000°C. The refractory structure of the gas heating furnace is determined according to the temperature of the internal area of ​​the gas heating furnace, which can not only effectively prevent SiO2 and H2 from reacting at high temperature to generate gaseous SiO and escaping, avoid silicon brick reaction, but also reduce costs.

[0016] Scheme 5, which is the preferred basic scheme, is a refractory structure of a hydrogen-rich carbon circulating oxygen blast furnace gas heating furnace, characterized in that the refractory structure is built from bottom to top with low creep clay lattice bricks, clay lattice bricks, low creep clay lattice bricks, low creep high aluminum lattice bricks, siliceous lattice bricks and corundum mullite lattice bricks; the refractory structure of the gas heating furnace is determined according to the temperature of each area in the gas heating furnace, which can not only effectively prevent SiO2 and H2 from reacting at high temperature to generate gaseous SiO and escaping, avoiding the reaction of silica bricks, but also arranges high-temperature resistant and high-strength high-aluminum refractory materials on the top of the silica bricks, which can also prevent the refractory materials from being damaged and failing.

[0017] Scheme six, which is the preferred embodiment of scheme five, the low-temperature section is built with low-creep clay checker bricks and clay checker bricks, the low-creep clay checker bricks and clay checker bricks are built with 4 and 93 layers respectively, the composition ratio of the low-creep clay checker bricks is: Al2O342-53%, Fe≤1%, CaO+MgO≤0.7%, Na2O+K2O≤0.8%, the composition ratio of the clay checker bricks is: Al2O342-53%, Fe≤1%, CaO+MgO≤0.7%, Na2O+K2O≤0.8%; the composition ratio of Al2O3, Fe, CaO+MgO, Na2O+K2O and SiO2 in the refractory material ensures the strength and high temperature resistance of the refractory material, so that the volume of the refractory material is relatively stable when used for a long time at high temperature, and it is not easy to deform.

[0018] Option seven, which is the preferred option of Option five, the medium temperature section adopts low creep clay checker bricks and low creep high alumina checker bricks, the low creep clay checker bricks and low creep high alumina checker bricks are built in 25 layers and 25 layers respectively, the composition ratio of the low creep high alumina checker bricks is: Al2O365%-80%, Fe<0.5%; the composition ratio of Al2O3, Fe, CaO+MgO, Na2O+K2O and SiO2 in the refractory material ensures the strength and high temperature resistance of the refractory material, so that the volume of the refractory material is relatively stable when used for a long time at high temperature and is not easy to deform.

[0019] Option 8 is the preferred option of Option 5. The high-temperature section is built with siliceous lattice bricks and corundum mullite lattice bricks. The siliceous lattice bricks and corundum mullite lattice bricks are built with 67 layers and 5 layers respectively. The composition ratio of the siliceous lattice bricks is: SiO2 93%-98%, Fe<0.5%, and the composition ratio of the corundum mullite lattice bricks is: Al2O3>85%, Fe<0.5%. High-aluminum refractory materials with high temperature resistance and high strength are arranged on the top of the refractory structure to prevent the refractory materials from being damaged and failing, and to reduce costs.

[0020] Option nine, which is the preferred option of option five, the performance indicators of the low creep high alumina checker bricks are: apparent porosity <20%, load softening temperature >1650°C, the performance indicators of the siliceous checker bricks are: apparent porosity <20%, load softening temperature >1650°C, the performance indicators of the corundum mullite checker bricks are: apparent porosity <19%, load softening temperature >1700°C, thermal shock resistance greater than 30 times; the strength and high temperature resistance of the refractory material are guaranteed, so that the volume of the refractory material is relatively stable when used for a long time at high temperature, and it is not easy to deform. The lower the apparent porosity, the higher the mechanical strength of the refractory material, and it can also reduce the contact area with the slag in the furnace.

[0021] Option 10 is the preferred option of Option 5. The heights of the low creep clay lattice bricks, clay lattice bricks, low creep clay lattice bricks, low creep high alumina lattice bricks, siliceous lattice bricks and corundum mullite lattice bricks are all 120 mm. The height of each refractory material is consistent, which is convenient for subsequent construction by the staff. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The invention discloses a ternary phase diagram of SiO2-CaO-Al2O3 in a refractory structure of a hydrogen-rich carbon circulating oxygen blast furnace gas heating furnace and a method for determining the refractory structure. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below through specific embodiments:

[0024] Example 1

[0025] like Figure 1 As shown, a method for determining the refractory structure of a hydrogen-rich carbon circulating oxygen blast furnace gas heating furnace comprises the following steps:

[0026] S1: When selecting the refractory material for the gas heating furnace, the staff first sampled the used refractory material and analyzed the chemical composition. It was found that the content of SiO2 in the refractory material before use was 95.102wt%, the content of CaO was 2.585wt%, the content of Fe2O3 was 0.842wt%, the content of Al2O3 was 0.508wt%, and the content of K2O was 0.148wt%. The content of SiO2 in the refractory material after use was 91.954wt%, the content of CaO was 0.552wt%, the content of Fe2O3 was 0.184wt%, the content of Al2O3 was 1.331wt%, and the content of K2O was 0.26wt%. The contents of SiO2, CaO and Fe2O3 in the refractory material after use were all reduced compared with those in the refractory material before use, while the contents of Al2O3 and K2O were all increased compared with those in the refractory material before use;

[0027] S2: The staff will conduct XRD test on the refractory materials before and after use. Through XRD test, the crystal structure, lattice constant, grain size, crystal orientation and relative content of the sample can be determined. It is found that the crystal phase structure of SiO2 in the refractory materials before and after use has changed, and the phase in the refractory materials after use has been completely transformed from phosphorus quartz to quartz;

[0028] S3: Then, based on thermodynamics, we infer the release path of SiO2 and the reaction mechanism of Al2O3 in a reducing atmosphere after the reducing CO and H2 react with the refractory material at high temperature. We find that the only way for SiO2 to be released at high temperature is to generate gaseous SiO, and Al2O3 does not react in a reducing atmosphere.

[0029] S4: According to the results of SiO2 escape path, it is concluded that the initial generation temperature of SiO is about 1300℃ under 1 atmosphere. As the pressure increases, the generation temperature of SiO increases. However, under 5 atmospheres, the generation temperature of SiO is still lower than 1500℃, so it is determined that the replacement material for the silicon refractory material in the high temperature zone of the gas heating furnace is corundum mullite checker brick;

[0030] S5: According to the temperature field distribution diagram, it is determined that the refractory structure is laid from bottom to top with 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;

[0031] S6: Finally, the operator will carry out on-site construction preparation and carry out refractory masonry work according to the determined refractory structure. After the masonry is completed, the furnace shell is sealed to complete the construction.

[0032] In summary, in Example 1, by analyzing the chemical composition of the refractory material after use, it is concluded that the contents of SiO2, CaO and Fe2O3 in the refractory material after use are lower than those of the refractory material before use, while the contents of Al2O3 and K2O are higher than those of the refractory material before use, thereby concluding that the refractory material has lost weight by about 6%. The escape path of SiO2 in the refractory material and the reaction mechanism of Al2O3 under a reducing atmosphere are used to determine the alternative material for the upper high-temperature zone of the gas heating furnace. Finally, the structure of the refractory material of the gas heating furnace and the height of each layer are determined through the temperature field distribution diagram, and finally the minimum temperature of the silicon brick interface is increased from 720°C to 790°C, which is far away from the crystal phase transition point of silicon brick at 600°C, effectively preventing SiO2 from reacting with H2 at high temperature to generate gaseous SiO and escaping, avoiding the silicon brick reaction, thereby preventing the refractory material from being damaged and causing failure. After the refractory material is modified, the service life of the gas heating furnace is extended to 5-10 years. If the gas heating furnace is built from bottom to top with 4 layers of low creep clay checker bricks, 106 layers of clay checker bricks, 25 layers of low creep clay checker bricks and 84 layers of siliceous checker bricks, the furnace skin will turn red after about one year of use, and the gas heating furnace may even collapse.

[0033] 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 determining the refractory structure of a hydrogen-rich carbon cycle oxygen blast furnace gas heating furnace, characterized in that: The following steps are involved: S1: When selecting refractory materials for gas heating furnaces, the staff will first take samples of the used refractory materials and perform chemical composition analysis; S2: The staff will conduct XRD test on the refractory materials before and after use; S3: Then, based on thermodynamics, we can infer the release path of SiO2 and the reaction mechanism of Al2O3 in a reducing atmosphere after the reducing CO and H2 react with the refractory material at high temperature; S4: Determine the replacement material for the silicon refractory material in the high temperature zone of the gas heating furnace according to the result of the SiO2 escape path; S5: Determine the masonry height of each refractory material in the gas heating furnace according to the temperature field distribution diagram; S6: Finally, the operator will carry out on-site construction preparation and refractory masonry.

2. The method for determining the refractory structure of a hydrogen-rich carbon cycle oxygen blast furnace gas heating furnace according to claim 1, characterized in that: In S1, the SiO2 content of the refractory material before use was 95.102wt%, the CaO content was 2.585wt%, the Fe2O3 content was 0.842wt%, the Al2O3 content was 0.508wt%, and the K2O content was 0.148wt%. The SiO2 content of the refractory material after use was 91.954wt%, the CaO content was 0.552wt%, the Fe2O3 content was 0.184wt%, the Al2O3 content was 1.331wt%, and the K2O content was 0.26wt%.

3. The method for determining the refractory structure of a hydrogen-rich carbon cycle oxygen blast furnace gas heating furnace according to claim 1, characterized in that: In S3, SiO2 is reduced to SiO at a temperature of 1300°C-1500°C in the CO-H2 coexistence system, and does not react with Al2O3 in the CO-H2 coexistence system.

4. The method for determining the refractory structure of a hydrogen-rich carbon cycle oxygen blast furnace gas heating furnace according to claim 1, characterized in that: In S5, the temperature field is divided into a low temperature section, a medium temperature section and a high temperature section. The temperature of the low temperature section is ≤500°C, the temperature of the medium temperature section is: 500°C < medium temperature section temperature <800°C, and the temperature of the high temperature section is: 800°C ≤ high temperature section temperature <1000°C.

5. A refractory structure for a hydrogen-rich carbon circulating oxygen blast furnace gas heating furnace, characterized in that: The refractory structure is built from bottom to top with low creep clay checker bricks, clay checker bricks, low creep clay checker bricks, low creep high alumina checker bricks, siliceous checker bricks and corundum mullite checker bricks.

6. The refractory structure of a hydrogen-rich carbon circulating oxygen blast furnace gas heating furnace according to claim 5, characterized in that: The low-temperature section is built with low-creep clay checker bricks and clay checker bricks. The low-creep clay checker bricks and clay checker bricks are built with 4 and 93 layers respectively. The composition ratio of the low-creep clay checker bricks is: Al2O342-53%, Fe≤1%, CaO+MgO≤0.7%, Na2O+K2O≤0.8%. The composition ratio of the clay checker bricks is: Al2O342-53%, Fe≤1%, CaO+MgO≤0.7%, Na2O+K2O≤0.8%.

7. The refractory structure of a hydrogen-rich carbon circulating oxygen blast furnace gas heating furnace according to claim 5, characterized in that: The medium temperature section is built with low creep clay checker bricks and low creep high alumina checker bricks, the low creep clay checker bricks and low creep high alumina checker bricks are built in 25 layers and 25 layers respectively, and the composition ratio of the low creep high alumina checker bricks is: Al2O365%-80%, Fe<0.5%.

8. The refractory structure of a hydrogen-rich carbon circulating oxygen blast furnace gas heating furnace according to claim 5, characterized in that: The high temperature section is built with siliceous lattice bricks and corundum mullite lattice bricks, and the siliceous lattice bricks and corundum mullite lattice bricks are built with 67 layers and 5 layers respectively. The composition ratio of the siliceous lattice bricks is: SiO2 93%-98%, Fe<0.5%, and the composition ratio of the corundum mullite lattice bricks is: Al2O3>85%, Fe<0.5%.

9. The refractory structure of a hydrogen-rich carbon circulating oxygen blast furnace gas heating furnace according to claim 5, characterized in that: The performance indicators of the low creep high alumina checker brick are: apparent porosity <20%, load softening temperature >1650°C, the performance indicators of the siliceous checker brick are: apparent porosity <20%, load softening temperature >1650°C, the performance indicators of the corundum mullite checker brick are: apparent porosity <19%, load softening temperature >1700°C, and thermal shock resistance greater than 30 times.

10. The refractory structure of a hydrogen-rich carbon circulating oxygen blast furnace gas heating furnace according to claim 5, characterized in that: The heights of the low creep clay checker bricks, clay checker bricks, low creep clay checker bricks, low creep high alumina checker bricks, siliceous checker bricks and corundum mullite checker bricks are all 120 mm.

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