A method of prolonging the life of the refractory lining of a circulating fluidized bed coal gasifier

Abstract

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

Description

Technical Field

[0001] This invention relates to a method for extending the service life of refractory linings in circulating fluidized bed gasifiers, belonging to the field of coal chemical technology. Background Technology

[0002] Existing coal-to-gas conversion processes generally suffer from low efficiency and severe environmental pollution. However, circulating fluidized bed (CFB) pulverized coal gasifiers stand out in the coal chemical industry due to their high recycling rate. Their industrial advantages include: the CFB gasifier returns separated material to the mains for secondary gasification via a return feeder, thereby increasing the coal yield per ton and gasification intensity, and improving coal utilization; the use of high-temperature air gasification improves gas quality and thermal gas utilization efficiency. CFB pulverized coal gasifiers are adaptable to various coal types, utilizing pulverized coal and low-calorific-value coal; the gas produced by the fluidized bed gasifier does not contain tar or harmful phenolic substances, simplifying the gas purification system and reducing atmospheric pollution. However, in circulating fluidized bed gasifiers, the gasifier uses highly reactive fuels (such as lignite) within the furnace body. Gas is produced by fluidizing the lignite under high pressure and high speed. Because the lignite particle size is approximately 3-10 mm, and given the strong heat transfer capacity of the fluidized bed, the coal is heated to the furnace temperature almost instantly upon entering the furnace. Moisture evaporation, volatile matter decomposition, tar cracking, carbon combustion, and gasification occur almost simultaneously. Some coal particles begin to melt before they have time to pyrolyze and react with the gasifying agent. These molten coal particles are highly viscous and can come into contact with other particles to form larger particles, potentially leading to coking and damaging the furnace lining refractory. Simultaneously, the high-pressure, high-speed airflow carrying coal dust erodes the refractory within the gasifier, requiring the refractory lining to withstand the high temperature, high-speed airflow, and coal dust erosion. Therefore, extending the service life of the refractory in the gasifier is a technical problem that needs to be solved. Summary of the Invention

[0003] To address the technical problems existing in the prior art, the purpose of this invention is to provide a method for extending the service life of the refractory lining of a circulating fluidized bed gasifier. This method involves adding nickel ore powder to the pulverized coal raw material, which can form a protective shell on the surface of the refractory lining during the coal gasification reaction in the fluidized bed, effectively extending the service life of the refractory lining, reducing equipment maintenance costs, and solving the technical problem of short service life of the refractory lining of the gasifier.

[0004] To achieve the above-mentioned technical objectives, the present invention provides a method for extending the service life of the refractory lining of a circulating fluidized bed gasifier. The method involves adding nickel ore powder to pulverized coal during the normal production process of the circulating fluidized bed gasifier, and having the pulverized coal enter the furnace chamber of the gasifier together for fluidization reaction.

[0005] During the fluidized bed reaction of pulverized coal, 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. 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 adhered to the furnace wall, forming a hard slag-iron protective shell on the contact surface between the furnace refractory and the high-temperature gas, thereby effectively protecting the furnace refractory and extending its service life.

[0006] As a preferred embodiment, the main components and mass content 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 in a circulating fluidized bed gasifier, the components in the nickel ore powder 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 embodiment, the nickel ore powder has a particle size of -6mm (the undersize material passing through a 6mm mesh sieve). By adjusting the particle size of the added nickel ore powder, its fluidization and splashing height on the inner wall of the furnace can be controlled, thereby controlling the specific location where a protective shell layer forms on the surface of the furnace lining. More preferably, the nickel ore powder can be selected from three particle size levels: -6mm to +4mm, -4mm to +2mm, and -2mm. These can respectively correspond to the protection needs of the furnace lining refractory material in areas within 10 meters, 10 to 20 meters, and 20 to 30 meters from the bottom of the gas furnace. The larger the particle size, the lower the splashing height. If a large area of ​​the furnace lining refractory material needs protection, a combination of nickel ore powders with different particle size levels can be used.

[0008] As a preferred embodiment, the nickel ore powder is added to the pulverized coal at a rate of 0.2-0.8% of the pulverized coal mass, with a continuous addition time of 8-16 hours. If the amount added is too small, it will be 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 will not further improve the protective effect on the refractory material of the inner wall of the furnace, but will instead reduce the furnace capacity. It is best to control the thickness of the protective shell to ≤5mm.

[0009] As a preferred embodiment, the reaction temperature inside the gasifier furnace is 600~900℃. At this preferred temperature, nickel ore powder can be partially reduced inside the furnace and combine with the corresponding molten slag to form a molten high-temperature slag-iron mixture.

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

[0011] As a preferred embodiment, the nickel ore powder is added after the circulating fluidized bed gasifier produces qualified gas, or when a problem occurs in the refractory lining of the circulating fluidized bed gasifier, causing a local temperature rise.

[0012] Compared with existing technologies, the beneficial technical effects of the present invention are as follows:

[0013] This invention adds nickel ore powder to pulverized coal, and utilizes the high temperature and reducing conditions generated by fluidization of the nickel ore powder to form a high-temperature slag-iron mixture. This mixture forms a stable and corrosion-resistant protective shell on the surface of the furnace lining refractory material. Without requiring equipment shutdown for maintenance, this effectively protects the gasifier furnace lining refractory material, extends its service life, reduces equipment costs, and makes a significant contribution to the company's environmental protection and economic cycle. Attached Figure Description

[0014] Figure 1 This is a process flow diagram of the present invention.

[0015] Figure 2 The results of testing the furnace wall temperature of the circulating fluidized bed gasifier using an infrared thermal scanner were obtained before adding nickel ore powder in Example 1.

[0016] Figure 3 The results of testing the furnace wall temperature of the circulating fluidized bed gasifier using an infrared thermal scanner were obtained after adding nickel ore powder to Example 1. Detailed Implementation

[0017] The following specific embodiments are intended to further illustrate the content of the present invention, rather than to limit the scope of protection of the claims of the present invention.

[0018] The main components and their mass content of the nickel ore powder in the following specific embodiments are as follows: Ni 1.6%; Fe 18%; SiO2 36%; MgO 22%; Al2O3 2.4%, with the balance being other impurities.

[0019] Example 1

[0020] 1) During normal production of the circulating fluidized bed gasifier, the furnace temperature is approximately 700℃. Infrared thermal scanning revealed multiple localized temperature points exceeding 400℃ within a 10-meter radius of the furnace wall. This confirms corrosion of the furnace wall refractory material, and the area requiring protection is defined as the region within 10 meters of the furnace bottom. Specifically... Figure 2 As shown, the local temperature point reached 400℃, reflecting partial corrosion of the refractory material.

[0021] 2) Add nickel ore powder with a particle size of +4mm to -6mm to the coal bunker and mix it with lignite. The amount added is 0.5% of the mass of lignite.

[0022] 3) Nickel ore powder was continuously added while monitoring the furnace wall temperature. It was observed that after 8 hours, the area of ​​areas with excessively high local temperatures on the furnace wall significantly decreased, and the furnace wall temperature dropped. Specifically, as shown below... Figure 3 As shown, the local temperature points decreased and the area decreased significantly, and the furnace wall temperature decreased, which played a role in protecting the refractory material. After 10 hours, there were no local temperature points on the furnace wall that were too high, at which point the addition of nickel ore powder was stopped.

[0023] Example 2

[0024] 1) During the normal production process of the circulating fluidized bed gasifier, the temperature inside the furnace is about 800℃. The infrared thermal scanner shows that there are multiple local temperature points with higher temperatures, reaching 500℃, in the area of ​​10m to 20m from the bottom of the furnace wall. This confirms that the furnace wall refractory material is corroded, and the height range that needs to be protected is the area of ​​10m to 20m from the bottom of the furnace.

[0025] 2) Add nickel ore powder with a particle size of -4mm to +2mm to the coal bunker and mix it with lignite. The amount added is 0.6% of the mass of lignite.

[0026] 3) Continue to add nickel ore powder while monitoring the furnace wall temperature. After 9 hours, the area of ​​localized high temperature points on the furnace wall will decrease significantly, and the furnace wall temperature will decrease. After 14 hours, there will be no localized high temperature points on the furnace wall. At this point, stop adding nickel ore powder.

Claims

1. A method for extending the service life of the refractory lining of a circulating fluidized bed gasifier, 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 gasifier furnace together with the coal powder for fluidization reaction; The main components and mass content of the nickel ore powder are as follows: Ni 1.5~1.7%; Fe 15~20%; SiO2 32~38%; MgO 19~25%; Al2O3 1.5~3.0%; The nickel ore powder has a particle size of -6mm.

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

3. The method for extending the service life of the refractory lining of a circulating fluidized bed gasifier according to claim 1, characterized in that: The reaction temperature inside the gasifier furnace is 600~900℃.

4. The method for extending the service life of the refractory lining of a circulating fluidized bed gasifier according to claim 1, characterized in that: The coal powder is lignite powder.

5. The method for extending the service life of the refractory lining of a circulating fluidized bed gasifier according to claim 1, characterized in that: The nickel ore powder is added after the circulating fluidized bed gasifier produces qualified gas, or when a problem occurs in the refractory lining of the circulating fluidized bed gasifier, causing a local temperature rise.

Images