Method for prolonging service life of furnace lining refractory material of circulating fluidized bed gas furnace

Abstract

The invention discloses a method for prolonging the service life of a circulating fluidized bed gas furnace lining refractory material, and belongs to the technical field of coal chemical industry. According to the method, nickel ore powder is added into a pulverized coal raw material, a protective shell can be formed on the surface of the furnace lining refractory material in the coal gasification reaction process of a fluidized bed, the service life of the refractory material is effectively prolonged, the equipment maintenance cost is reduced, and the technical problem that the service life of the gas furnace lining refractory material is short is solved.

Description

Technical Field

[0001] The invention relates to a method for prolonging the service life of lining refractory materials of a circulating fluidized bed gas furnace, belonging to the technical field of coal chemical industry. Background Art

[0002] The coal-to-gas process in the existing technology generally has many problems such as low efficiency and serious environmental pollution. However, the circulating fluidized bed pulverized coal gasification furnace stands out in the coal chemical industry due to its high recycling rate. Its industrial advantages: The circulating fluidized bed gasifier returns the separated return material to the material for secondary gasification through the return device, thereby increasing the ton coal output and gasification intensity of pulverized coal gasification and improving the utilization rate of coal; the high-temperature air gasification process is used to improve the quality of coal gas and the utilization efficiency of hot coal gas. The circulating fluidized bed pulverized coal gasification furnace has good adaptability to coal types and can utilize pulverized coal and low calorific value coal; the gas produced by the fluidized bed gasifier does not contain tar and phenolic harmful substances, which simplifies the gas purification system and reduces pollution to the atmospheric environment. However, in the circulating fluidized bed gasifier, a fuel with high gasification reactivity (such as lignite) is used in the gasifier body to produce gas by fluidizing lignite with high pressure and high speed air. Since the lignite particle size is about 3 to 10 mm, and the particle size is small, coupled with the strong heat transfer capacity of the fluidized bed, the coal is heated to the furnace temperature the moment it enters the furnace, and the evaporation of water, decomposition of volatiles, cracking of tar, combustion and gasification of carbon are almost carried out at the same time. Some coal particles begin to melt before they have time to pyrolyze and react with the gasifier. The molten coal particles are highly viscous and can contact with other particles to form larger particles, which may cause coking and damage the lining refractory. At the same time, in the gasifier body, lignite is fluidized with high pressure and high speed air to produce gas, and the high temperature and high speed airflow washes the refractory with coal powder, so the lining refractory is required to withstand the high temperature, high speed airflow and coal powder washing. In summary, extending the service life of refractory in the gasifier is a technical problem to be solved. Summary of the invention

[0003] In view of the technical problems existing in the prior art, the purpose of the present invention is to provide a method for extending the life of the refractory materials of the lining of a circulating fluidized bed gas furnace. The method is to add nickel ore powder to the coal powder raw material, so that a protective shell can be formed on the surface of the refractory materials of the lining during the gasification reaction of the fluidized bed, thereby effectively extending the life of the refractory materials, reducing equipment maintenance costs, and solving the technical problem of short life of the refractory materials of the gas furnace lining.

[0004] In order to achieve the above technical objectives, the present invention provides a method for extending the life of refractory materials of the lining of a circulating fluidized bed gas furnace. The method is that during the normal production process of the circulating fluidized bed gas furnace, nickel ore powder is added to coal powder, and the nickel ore powder enters the gas furnace furnace together with the coal powder for fluidization reaction.

[0005] During the fluidized reaction of coal powder, since the furnace reaction temperature can reach 600~900℃, the main components of nickel ore powder are iron oxides and MgO, SiO2, Al2O3, etc., which will be partially reduced in the furnace. For example, the reduction process of iron oxides is Fe2O3-Fe3O4-FeO, and FeO combines with MgO, SiO2, Al2O3, etc. to form a molten high-temperature slag iron mixture. This mixture has strong adhesion and can be evenly splashed and attached to the furnace wall, forming a hard slag iron protective shell on the contact surface between the furnace refractory and the high-temperature coal gas, thereby achieving the purpose of effectively protecting the furnace refractory and extending its service life.

[0006] As a preferred solution, the main components and mass contents of the nickel ore powder are: Ni 1.5~1.7%; Fe 15~20%; SiO2 32~38%; MgO 19~25%; Al2O3 1.5~3.0%. The main components of the nickel ore powder of the present invention are iron oxides and MgO, SiO2, Al2O3, etc. Under the reducing atmosphere of normal production of a circulating fluidized bed gas furnace, the components of the nickel ore powder itself can form a special Fe-Mg-Si-Al phase, which has good adhesion and can adhere to the surface of the furnace lining refractory to form a stable, hard, and refractory protective shell.

[0007] As a preferred solution, the particle size of the nickel ore powder is -6mm (screened through a 6mm mesh). By adjusting the particle size of the added nickel ore powder, its fluidized splash height on the inner wall of the furnace can be controlled, thereby controlling the specific location of the protective shell layer formed on the surface of the furnace refractory. More preferably, the particle size of the nickel ore powder can be selected from three particle size levels: -6mm~+4mm, -4mm~+2mm, and -2mm, which can respectively correspond to the needs of protecting the lining refractory materials of the gas furnace within 10 meters, 10~20 meters, and 20~30 meters from the bottom of the furnace. The larger the particle size, the lower the splash height. If a large area of ​​lining refractory materials needs to be protected, a combination of nickel ore powders of various particle size levels can be used.

[0008] As a preferred solution, the amount of nickel ore powder added to the coal powder is 0.2-0.8% of the mass of the coal powder, and the continuous addition time is 8-16 hours. If the amount added is too small, it is difficult to form a complete protective layer on the inner wall of the furnace. If the amount added reaches a certain level, further increasing the amount added will not further improve the protective effect of the refractory material on the inner wall of the furnace, but will reduce the furnace capacity. It is best to control the thickness of the protective shell to ≤5mm.

[0009] As a preferred solution, the reaction temperature in the furnace of the gasifier is 600-900° C. At the preferred temperature, the nickel ore powder can be partially reduced in the furnace and combined with the corresponding slag to form a molten high-temperature slag-iron mixture.

[0010] As a preferred solution, the coal powder is lignite powder.

[0011] As a preferred solution, the nickel ore powder is added after the circulating fluidized bed gasifier produces qualified coal gas, or is added when problems occur in the lining refractory of the circulating fluidized bed gasifier, causing local temperature points to rise.

[0012] Compared with the prior art, the technical solution of the present invention has the following beneficial technical effects: The present invention adds nickel ore powder to coal powder, utilizes the nickel ore powder to form a high-temperature slag-iron mixture under the temperature generated by fluidization and reducing conditions, and forms a stable and corrosion-resistant protective shell on the surface of the furnace lining refractory. Under the premise of not shutting down the equipment for maintenance, the refractory of the gas furnace lining is effectively protected, the life of the refractory is extended, the equipment cost is reduced, and a huge contribution is made to the environmental protection and economic cycle of the enterprise. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a process flow chart of the present invention.

[0014] Figure 2 The results of testing the furnace wall temperature of the circulating fluidized bed gas furnace using an infrared thermal scanner before adding nickel ore powder in Example 1.

[0015] Figure 3 The results of testing the furnace wall temperature of the circulating fluidized bed gas furnace using an infrared thermal scanner after adding nickel ore powder to Example 1. DETAILED DESCRIPTION

[0016] The following specific examples are intended to further illustrate the present invention, rather than to limit the scope of protection of the claims of the present invention.

[0017] The main components and mass contents of the nickel ore powder in the following specific examples are: Ni 1.6%; Fe 18%; SiO 2 36%; MgO 22%; Al 2 O 3 2.4%, and the remainder is other impurities.

[0018] Example 1

[0019] 1) During the normal production of the circulating fluidized bed gas furnace, the temperature in the furnace is about 700°C. The infrared thermal scanner shows that there are multiple local temperature points within the 10-meter area of ​​the circulating fluidized bed gas furnace wall, which are higher than 400°C. This confirms that the furnace wall refractory material is corroded and the height range that needs to be protected is within the 10-meter area from the furnace bottom. Figure 2 As shown, the local temperature point reaches 400℃, reflecting the corrosion of some resistant materials.

[0020] 2) Add nickel ore powder with a particle size of +4mm~-6mm into the coal bunker and mix it with lignite. The added amount is 0.5% of the mass of the lignite.

[0021] 3) Continuously add nickel ore powder and pay attention to the furnace wall temperature. It is found that after 8 hours, the area of ​​the local high temperature point on the furnace wall is significantly reduced, and the furnace wall temperature is reduced. Figure 3 As shown, the local temperature point is reduced and the area is significantly reduced, the furnace wall temperature is reduced, which plays a role in protecting the refractory material. After 10 hours, there is no local high temperature point on the furnace wall, at this time, stop adding nickel ore powder.

[0022] Example 2

[0023] 1) During the normal production of the circulating fluidized bed gasifier, the temperature in the furnace is about 800°C. The infrared thermal scanner shows that there are multiple local temperature points in the area 10m~20m away from the furnace bottom of the circulating fluidized bed gasifier, which are relatively high, reaching 500°C. This confirms that the refractory material of the furnace wall is corroded and the height range that needs to be protected is within the area 10m~20m away from the furnace bottom.

[0024] 2) Add nickel ore powder with a particle size of -4mm~+2mm into the coal bunker and mix it with lignite. The added amount is 0.6% of the mass of the lignite.

[0025] 3) Continue to add nickel ore powder while paying attention to the temperature of the furnace wall. It is found that after 9 hours, the area of ​​the local high temperature points on the furnace wall is significantly reduced and the furnace wall temperature is reduced. After 14 hours, there is no local high temperature point on the furnace wall. At this time, stop adding nickel ore powder.

Claims

1. A method for extending the life of refractory materials of circulating fluidized bed gas furnace lining, characterized in that: During the normal production process of the circulating fluidized bed gasifier, nickel ore powder is added to the coal powder and enters the furnace of the gasifier together with the coal powder for fluidization reaction.

2. The method for extending the life of the lining refractory of a circulating fluidized bed gas furnace according to claim 1, characterized in that: The main components and mass contents of the nickel ore powder are: Ni 1.5-1.7%; Fe 15-20%; SiO2 32-38%; MgO 19-25%; Al2O3 1.5-3.0%.

3. A method for extending the life of refractory materials of circulating fluidized bed gas furnace lining according to claim 1 or 2, characterized in that: The particle size of the nickel ore powder is -6mm.

4. A method for extending the life of refractory materials of circulating fluidized bed gas furnace lining according to claim 1 or 2, characterized in that: The nickel ore powder is added to the coal powder in an amount of 0.2-0.8% of the mass of the coal powder, and the continuous addition time is 8-16 hours.

5. The method for extending the life of the lining refractory of a circulating fluidized bed gas furnace according to claim 1, characterized in that: The reaction temperature in the furnace of the gas furnace is 600-900°C.

6. A method for extending the life of refractory materials of circulating fluidized bed gas furnace lining according to claim 1, characterized in that: The coal powder is lignite powder.

7. A method for extending the life of refractory materials of circulating fluidized bed gas furnace lining according to claim 1 or 2, characterized in that: The nickel ore powder is added after the circulating fluidized bed gasifier produces qualified coal gas, or is added when problems occur in the lining refractory of the circulating fluidized bed gasifier, causing local temperature points to rise.

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