Gasifier start-up burner seat gradient cooling composite sealing structure and installation method

Abstract

The application discloses a kind of gradient cooling composite sealing structure and installation method of start-up burner seat of gasification furnace, it is related to the sealing technical field of water-cooled wall of gas flow bed gasification furnace.The structure includes sleeve and cooling coil, the lower part of sleeve is circular truncated cone, side angle is 60 °~75 °;Truncated cone side is distributed with slag nail, its density gradually decreases from bottom to top;Truncated cone side and main water-cooled wall slope form sealing gap and fill sealing material;Cooling coil is coiled in sleeve, and the density gradually decreases from bottom to top, and radial fin is welded on the outer wall of coil pipe and embedded in sealing material;The composite structure of bottom fire surface of start-up burner seat adopts the welding of coil pipe and fin and fills silicon carbide protective layer.The application is avoided by slope, gradient anchoring, gradient cooling and layered protection synergistic effect, effectively avoids the direct scouring of multi-nozzle opposed gasification furnace dome rising gas flow, solves the problem of annular cavity over-temperature caused by leakage of start-up burner seat sealing surface, improves the safety and operation cycle of device.

Description

Technical Field

[0001] This invention relates to the field of water-cooled wall sealing technology for fluidized bed gasifiers, and more specifically, to a gradient cooling composite sealing structure for the burner seat during gasifier startup and its installation method. Background Technology

[0002] Water-cooled wall gasifiers employ a "slag-against-slag" lining design, offering significant advantages such as long operating cycles and wide coal adaptability (especially capable of gasifying high ash fusion point coal). Currently, the mainstream water-cooled wall gasifiers in industrial operation are mainly classified into two types based on the arrangement of their pulverized coal burners: top-mounted (single or three burners) and multi-nozzle opposed (four or six burners).

[0003] For top-mounted gasifiers, a cylindrical sealing structure is generally used at the bottom of the burner seat during startup. When the top burner injects material, the high-speed jet will create an entrainment effect around it, resulting in a relatively low-pressure area near the burner seat. The high-temperature gas in the furnace generally will not enter the water-cooled wall ring cavity through the burner seat sealing gap, causing overheating.

[0004] For multi-nozzle opposed gasifiers, the start-up burners are usually located in the dome area at the top of the furnace. After the jets from the multiple opposed burners collide at the center of the furnace, they turn back and rise to the dome, forming a significant high-pressure zone in this area, which strongly erodes the sealing surface of the start-up burner seat located at the dome.

[0005] The burner seat, located in this high-pressure zone, experiences the greatest pressure difference between the inside and outside of the water-cooled wall annulus on its sealing surface. This sealing surface is typically a vertical cylinder, directly subjected to the intense scouring of the rising airflow. In actual operation, this cylindrical vertical sealing structure is highly susceptible to the sealing packing being dispersed and eroded by the high-temperature airflow, leading to seal failure. This, in turn, allows high-temperature gas to seep into the upper part of the water-cooled wall annulus, causing overheating and seriously threatening the safe, long-term operation of the unit. Summary of the Invention

[0006] The purpose of this invention is to solve the problems mentioned in the background art, and to propose a gradient cooling composite sealing structure for the burner seat during gasification start-up and an installation method.

[0007] The technical solution adopted by this invention to solve its technical problem is: A gradient cooling composite sealing structure for a gasifier burner seat during startup includes a sleeve and a cooling coil. The lower part of the sleeve is shaped like a frustum, and the angle between the side of the frustum and the horizontal direction is 60°~75°. Several slag nails are distributed along the circumferential and axial directions on the side of the frustum, and the distribution density of the slag nails on the side of the frustum gradually decreases from bottom to top. A sealing gap is formed between the side of the frustum and the corresponding inclined surface of the main water-cooled wall, and the gap is filled with sealing material. The sleeve is internally coiled and connected to the external cooling water inlet and outlet pipelines through the flange passing through the burner seat. The bottom of the burner seat is surrounded by coils, with fins welded between the coils. Slag nails are welded to the fire-facing side and filled with a silicon carbide protective layer.

[0008] Furthermore, the slag nails include a first type of slag nail located on the lower air-facing side of the truncated cone and a second type of slag nail located on the upper air-repellent side of the truncated cone. The first type of slag nail is a T-shaped slag nail, and the second type of slag nail is a straight rod-shaped slag nail.

[0009] Furthermore, the slag nails are arranged in multiple staggered rows on the side of the frustum, with adjacent rows of slag nails being staggered in the circumferential direction.

[0010] Furthermore, the winding density of the cooling coils inside the sleeve gradually decreases axially from bottom to top, with the coil spacing near the furnace side being d1 and the coil spacing away from the furnace side being d2. <d2。

[0011] Furthermore, radially extending fins are welded to the outer wall of the cooling coil, and the fins are embedded in the sealing material.

[0012] Furthermore, the fins are continuously arranged along the spiral direction of the cooling coil, and an anchoring space for accommodating sealing material is formed between adjacent fins.

[0013] Furthermore, the sealing material has a three-layer composite structure, consisting of an inner refractory fiber layer, a middle alumina hollow sphere castable layer, and an outer silicon carbide castable layer, from the inside out.

[0014] Furthermore, the sealing gap between the side of the frustum and the corresponding inclined surface of the main water-cooled wall is 40mm.

[0015] Furthermore, a method for installing the sealing structure of the burner seat in a multi-nozzle opposed fluidized bed gasifier includes the following steps: Step 1: Align the frustum-shaped sleeve with the main water-cooled wall at the designed angle, so that a sealing gap of a predetermined width is formed between the side of the frustum and the corresponding inclined surface of the main water-cooled wall. Step 2: Weld slag studs onto the side of the frustum, wherein the density of slag studs on the lower, gas-facing side of the frustum is greater than the density of slag studs on the upper, gas-repellent side of the frustum. Step 3: Fill the sealing gap with sealing material in layers. First, fill the inner refractory fiber layer, then fill the middle layer of alumina hollow sphere castable, and finally fill the outer silicon carbide castable layer. Step 4: Install the cooling coils, ensuring that the coil density gradually decreases from bottom to top along the axial direction, and connect the external cooling water inlet and outlet pipes.

[0016] Compared with the prior art, the beneficial effects of the present invention are: 1. Fundamentally improves the erosion resistance and integrity of the sealing surface. By replacing the traditional cylindrical vertical seal with a frustum-shaped inclined seal at an angle of 60°~75°, the direct impact of the rising airflow from the furnace dome is avoided, and the inclined structure decomposes and reduces the impact force layer by layer. Thermal simulation testing has verified that this structure significantly extends the service life of the sealing material compared to the traditional vertical structure, effectively solving the problem of annular gas leakage and overheating caused by packing loss.

[0017] 2. A gradient anchoring system precisely matched to the scouring intensity of the flow field was formed. T-shaped high-anchoring-force slag nails were used on the lower, air-facing side of the frustum, with increased distribution density. Straight-rod slag nails were used on the upper, air-repellent side, with multiple rows of circumferentially staggered slag nails. Combined with the anchoring space formed by the radial fins of the cooling coil, a multi-level, three-dimensional anti-detachment network was constructed. This design ensures reliable fixation in the high-scouring zone while also considering ease of construction. Even in the event of localized damage, it prevents large-area detachment of the sealing material.

[0018] 3. Gradient cooling and thermal stress homogenization are achieved. The density of cooling coils inside the sleeve gradually decreases from bottom to top, that is, the coil spacing d1 near the high heat load zone of the furnace is smaller than the coil spacing d2 away from the furnace zone. This ensures that the cooling intensity is precisely matched with the heat load distribution, avoids creep and thermal fatigue caused by local overheating, and greatly improves the reliability of the structure in long-term service.

[0019] 4. A composite protective layer for the fire-facing surface was constructed using slag to resist slag. The bottom fire-facing surface of the burner seat at start-up adopts an integral cooling wall with coils and fins welded together. Slag nails are welded on it and filled with a silicon carbide protective layer. During operation, a stable liquid slag layer is formed on the surface, transforming passive protection into active heat insulation, providing a durable and effective thermal barrier for the water-cooled wall metal.

[0020] 5. The installation process is clearly structured, with three layers of composite material (refractory fiber layer, alumina hollow sphere castable layer, and silicon carbide castable layer) filling the sealing gap in sequence. Each layer plays a role in buffering, heat insulation, and erosion resistance, and forms a strong mechanical interlock with the anchoring structure, ensuring the construction quality and long-term stability of the overall sealing structure. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 A schematic diagram showing the orientation of the slag nails; Figure 3 A schematic diagram of the cooling coil installation; Figure 4 This is a schematic diagram of the sealing material structure; Figure 5 This is a schematic diagram showing the fin installation distribution; Figure 6 This is an overall flowchart of the present invention; Figure label: 1. Sleeve; 2. Cooling coil; 21. Inlet pipe; 22. Return pipe; 3. Slag nail; 31. Type I slag nail; 32. Type II slag nail; 4. Sealing material; 41. Refractory fiber layer; 42. Alumina hollow sphere castable layer; 43. Silicon carbide castable layer; 5. External cooling water inlet and return pipes; 6. Fins; 7. Silicon carbide protective layer. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0023] This invention addresses the flow field characteristics of the furnace dome region in a multi-nozzle opposed-flow bed gasifier, proposing a gradient cooling composite sealing structure for the burner seat during gasifier startup and its installation method.

[0024] In the traditional structure, a cylindrical (vertical) seal is used between the burner seat and the main water-cooled wall. This sealing surface is directly exposed to the strong upward airflow formed at the dome after the burner material collides with it. The sealing material 4 is easily broken and damaged, causing high-temperature gas to enter the water-cooled wall annular cavity, triggering an upper over-temperature accident, which seriously threatens the safe long-term operation of the unit.

[0025] The core idea of ​​this invention is to change the sealing surface of the part bearing the greatest pressure difference from a vertical surface to a sloping surface, and to reduce the impact force of airflow layer by layer through a gradient-designed anchoring, cooling and protection structure, thereby completely solving the above problems.

[0026] Example 1: Sealing Structure like Figures 1 to 5 As shown, the structure mainly includes a sleeve 1 connected to the burner seat and a combined cooling and sealing system.

[0027] The sleeve 1 can be made of heat-resistant alloy steel, such as 15CrMoR, with a wall thickness of 10mm to ensure structural strength in high-temperature environments.

[0028] The lower part of sleeve 1 is shaped like a frustum, and the angle between the side of the frustum and the horizontal direction is a key flow field adaptability parameter. In this embodiment, the angle is selected as 65°. This angle range (60°~75°) can effectively guide the main body of the rising airflow impacting the sealing surface to the center of the furnace obliquely downward, rather than directly impacting the sealing gap, thus achieving the effects of "avoidance" and "force dissipation".

[0029] It should be clarified that the cooling coil 2 is arranged inside the wall thickness of the sleeve 1 or attached to its inner wall surface. The fins 6 extend radially outward along the cooling coil 2 and pass through the side wall of the sleeve 1, extending into the sealing gap between the side of the frustum and the inclined surface of the main water-cooled wall. This increases the heat exchange area while embedding the fins into the sealing material 4 to form a mechanical anchor. This spatial layout ensures direct cooling of the sleeve body by the cooling medium and couples the sealing material and cooling structure together through the fins, preventing the sealing material from delaminating from the cooling wall due to local thermal expansion.

[0030] Regarding concerns that the inclined surface seal may increase the sealing area, this application further explains as follows: Although the inclined surface increases the actual length of the sealing interface compared to the vertical surface under the condition of a certain radial projection width, the 60°~75° inclination angle guides the originally vertically impacting rising airflow to the center of the furnace at the lower angle. The normal component of the airflow acting at the inlet of the sealing gap is greatly reduced, and the effective scouring dynamic pressure is only 20%~30% of that of the vertical surface structure. At the same time, the lengthened inclined surface sealing path increases the friction resistance of the gas leakage. Combined with the internal multi-layer sealing material filling, it forms a more reliable flow barrier than the vertical surface seal.

[0031] On the side of the frustum, several slag nails 3 are distributed along its circumference and axial direction to anchor the subsequent filling of sealing material 4. The distribution of the slag nails 3 is not uniform, but rather exhibits a gradient change: the density of slag nails 3 is highest in the air-facing region of the lower part of the frustum side, which first contacts the rising airflow, and gradually decreases towards the air-repellent region of the upper part of the frustum side. This design is based on the actual needs of stress and preventing detachment, providing the strongest anchoring force in the lower part where scouring is most severe.

[0032] Furthermore, the types of slag nails 3 are also designed in a gradient manner according to their location and stress requirements. For example... Figure 2 As shown, the slag nail 3 located on the air-facing side of the lower part of the truncated cone is a first-class slag nail 31, specifically a T-shaped slag nail 3. Its forked or bent head can provide great anchoring force to prevent the sealing material 4 from being lifted up as a whole under strong airflow.

[0033] The slag studs 3 located on the upper part of the side surface of the circular truncated cone on the gas-back side are the second type of slag studs 32, which can specifically adopt straight-rod type slag studs 3, sufficiently meeting the shear resistance requirement of this region, and have a simple structure and are easy for construction. All the slag studs 3 are arranged in multiple staggered rows on the side surface of the circular truncated cone, and two adjacent rows of slag studs 3 are arranged in a circumferentially offset manner to form a three-dimensional anchoring network, so that the sealing material 4 is divided and fixed in a plurality of independent, mutually staggered tiny regions, and even local damage will not cause large-area falling off.

[0034] An annular sealing gap with a width of 40mm is formed between the side surface of the circular truncated cone and the corresponding inclined surface of the main water wall. This gap not only provides a tolerance adjustment space for manufacturing and installation, but more importantly, serves as a filling cavity to accommodate the sealing material 4 with erosion resistance and sealing functions. In a preferred embodiment, the sealing material 4 adopts a three-layer composite structure, which from the inside to the outside (i.e., from the side surface of the circular truncated cone close to the sleeve 1 toward the corresponding inclined surface of the main water wall) is sequentially as follows: The inner layer is a refractory fiber layer 41, serving as the first flexible buffer and sealing layer; The middle layer is an alumina hollow sphere castable layer 42, serving as the main high-temperature resistant and heat insulating layer; The outer layer is a silicon carbide castable layer 43, which directly faces potential gas leakage, and exerts the functions of high strength, erosion resistance and forming a liquid slag protective film.

[0035] A gradient cooling system is integrated inside the sleeve 1 and on the fire-facing surface at the bottom of the start-up burner seat. A cooling coil 2 is adopted inside the sleeve 1, which surrounds the inner cavity of the sleeve 1 in a coil form, and passes through the flange of the start-up burner seat to be connected with the external cooling water inlet and return pipelines. The coiling density of the cooling coil 2 gradually decreases from bottom to top along the axial direction (i.e., from the side close to the furnace to the side far away from the furnace). Specifically, in the high heat load zone close to the furnace side, the coil spacing is d1; in the low heat load zone far away from the furnace side, the coil spacing is d2, and d1<d2. Preferably, d1 is 50~80mm, and d2 is 100~150mm, so as to realize the precise matching of cooling intensity and heat load.

[0036] Simulation verification example: To verify the actual effect of gradient cooling, heat transfer simulation calculation is carried out under the same heat load condition in this embodiment. Taking the heat flux density of 250kW / m² on the furnace side as the boundary condition, under the working condition of the traditional uniform coil (with a spacing of 100mm), the metal wall temperature in the bottom high-temperature zone reaches 620℃, and the axial temperature difference is about 120℃; after adopting the gradient coil of this embodiment (d1=60mm, d2=120mm), the wall temperature in the bottom high-temperature zone drops to 540℃, and the axial temperature difference is reduced to about 45℃. The results show that the gradient cooling design makes the thermal stress distribution more uniform, and effectively avoids creep and thermal fatigue damage caused by local overheating.

[0037] Radially extending fins 6 are welded onto the outer wall of the cooling coil 2. The fins 6 are continuously arranged along the spiral direction of the cooling coil 2, and an anchoring space for accommodating the sealing material 4 is formed between adjacent fins 6. These fins 6 are embedded in the sealing material 4 (especially the alumina hollow sphere castable layer 42), which not only increases the heat exchange area, but also plays an additional anchoring role similar to slag nails 3.

[0038] The bottom of the burner seat directly bears the high temperature of the furnace on the fire-facing side. Slag nails 3 are welded to the fire-facing side wall, and a silicon carbide protective layer 7 is filled on the anchoring structure formed by the slag nails 3 and the coil fins 6. During operation, a layer of molten liquid slag will form on the surface of the silicon carbide protective layer 7, realizing "slag-resistant slag" and effectively protecting the metal cooling structure at the bottom.

[0039] To more intuitively demonstrate the technical advantages of this embodiment compared with the prior art, a comparative analysis is conducted based on the operating conditions of a multi-nozzle opposed water-cooled wall gasifier, as shown in Table 1.

[0040] Table 1. Performance Comparison of this Embodiment with Traditional Cylindrical Sealing Structure

[0041] As shown in Table 1, this invention systematically improves the reliability and lifespan of the burner seat seal during the start-up of a multi-nozzle opposed gasifier through comprehensive gradient design (structural gradient, anchoring gradient, cooling gradient, and material gradient), and completely solves the industry problem of annular cavity overheating caused by gas leakage in the high-pressure zone of the furnace dome.

[0042] Example 2: Installation Method Corresponding to the above structure, the present invention provides an installation method for the sealing structure of the start-up burner seat of a multi-nozzle opposed fluidized bed gasifier, the specific steps of which are shown in the appendix to the instruction manual. Figure 6 As shown, the specific details are as follows: Step 1: Alignment and Gap Formation The frustum-shaped sleeve 1 is precisely aligned with the main water-cooled wall at the designed angle (e.g., 65°). This creates a uniform annular sealing gap of 40mm between the side of the frustum-shaped sleeve 1 and the corresponding pre-reserved inclined surface on the main water-cooled wall. This gap is used to absorb dimensional deviations during manufacturing and installation, and to provide space for filling the sealing material 4.

[0043] Step 2: Welding of slag nail 3 Slag studs 3 are welded onto the side of the frustum. During welding, the gradient design principle is strictly followed to ensure that the density of slag studs 3 on the lower gas-facing side of the frustum is greater than that on the upper gas-repellent side of the frustum.

[0044] At the same time, different types of slag nails 3 are installed according to their positions. T-shaped slag nails are mainly arranged on the air-facing side, and straight rod-shaped slag nails 3 are arranged on the air-repelling side, so that the whole structure is arranged in multiple rows of axial and circumferential staggered arrangement.

[0045] Step 3: Fill with sealant in layers 4 Within the formed sealing gap, sealing material 4 is filled in layers from the inside out.

[0046] First, a flexible refractory fiber layer 41 is filled into the innermost part of the gap to serve as a buffer and initial seal. Secondly, on the outside of the refractory fiber layer 41, a layer of alumina hollow sphere castable is tamped or vibrated to form a dense heat-resistant and heat-insulating layer in the middle layer. In this step, it is ensured that the castable is fully embedded between the fins 6 of the cooling coil 2 and around the slag nails 3 to form a strong mechanical interlock. Finally, on the outermost side of the gap, that is, the side facing the possible gas leakage, a layer of silicon carbide castable is coated or poured to form a highly wear-resistant and erosion-resistant external protective layer.

[0047] Step 4: Installation and connection of cooling coil 2 Install the cooling coils 2 inside the sleeve 1 and at the bottom of the start-up burner seat. Ensure that the winding density of the cooling coils 2 inside the sleeve 1 is strictly arranged according to the design requirements, i.e., gradually decreasing from bottom to top along the axial direction, to enhance the cooling capacity of the high heat load area. After the inlet pipe 21 and return pipe 22 of the cooling coils 2 are connected, they reliably pass through the flange of the start-up burner seat and are connected to the external cooling water inlet and return headers, and pass the water pressure test. Finally, weld slag nails 3 to the fire-facing side at the bottom of the start-up burner seat and fill this area with a silicon carbide protective layer 7 to complete the entire installation process.

[0048] The sealing structure installed using the above method integrates multiple functions such as inclined flow avoidance, gradient anchoring, gradient cooling, and layered protection, providing a reliable solution for the weak points of the dome of a multi-nozzle opposed gasifier.

[0049] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A gradient cooling composite sealing structure for a gasifier burner seat during startup, comprising a sleeve (1) and a cooling coil (2), characterized in that: The lower part of the sleeve (1) is shaped like a frustum, and the angle between the side of the frustum and the horizontal direction is 60°~75°. Several slag nails (3) are distributed along the circumferential and axial directions on the side of the frustum. The distribution density of the slag nails (3) on the side of the frustum gradually decreases from bottom to top. A sealing gap is formed between the side of the frustum and the corresponding inclined surface of the main water-cooled wall, and the gap is filled with sealing material (4). The sleeve (1) is internally coiled and passes through the flange of the burner seat to connect with the external cooling water inlet and outlet pipeline (5); The bottom of the burner seat is surrounded by coils, with fins (6) welded between the coils. Slag nails (3) are welded to the fire-facing side and filled with a silicon carbide protective layer (7).

2. The gradient cooling composite sealing structure for the gasifier start-up burner seat according to claim 1, characterized in that: The slag nail (3) includes a first type of slag nail (31) located on the lower air-facing side of the side of the frustum and a second type of slag nail (32) located on the upper air-repellent side of the side of the frustum. The first type of slag nail (31) is a T-shaped slag nail, and the second type of slag nail (32) is a straight rod type slag nail.

3. The gradient cooling composite sealing structure for the gasifier start-up burner seat according to claim 1, characterized in that: The slag nails (3) are arranged in multiple staggered rows on the side of the frustum, with adjacent rows of slag nails (3) staggered in the circumferential direction.

4. The gradient cooling composite sealing structure for the gasifier start-up burner seat according to claim 1, characterized in that: The winding density of the cooling coils (2) inside the sleeve (1) gradually decreases from bottom to top along the axial direction. The coil spacing near the furnace side is d1, and the coil spacing away from the furnace side is d2. <d2。 5. The gradient cooling composite sealing structure for the gasifier start-up burner seat according to claim 1, characterized in that: The outer wall of the cooling coil (2) is welded with radially extending fins (6), which are embedded in the sealing material (4).

6. The gradient cooling composite sealing structure for the gasifier start-up burner seat according to claim 5, characterized in that: The fins (6) are continuously arranged along the spiral direction of the cooling coil (2), and an anchoring space for accommodating the sealing material (4) is formed between adjacent fins (6).

7. The gradient cooling composite sealing structure for the gasifier start-up burner seat according to claim 1, characterized in that: The sealing material (4) is a three-layer composite structure, consisting of an inner refractory fiber layer (41), a middle alumina hollow sphere castable layer (42), and an outer silicon carbide castable layer (43) from the inside out.

8. The gradient cooling composite sealing structure for the gasifier start-up burner seat according to claim 1, characterized in that: The sealing gap between the side of the frustum and the corresponding inclined surface of the main water-cooled wall is 40mm.

9. A method for installing a sealing structure for the burner seat during startup of a multi-nozzle opposed-flow gasifier, characterized in that, Includes the following steps: Step 1: Align the frustum-shaped sleeve (1) with the main water-cooled wall at the designed inclination angle, so that a sealing gap of a predetermined width is formed between the side of the frustum and the corresponding inclined surface of the main water-cooled wall; Step 2: Weld slag nails (3) onto the side of the frustum, wherein the density of the slag nails (3) located on the lower gas-facing side of the frustum is greater than the density of the slag nails (3) located on the upper gas-repellent side of the frustum. Step 3: Fill the sealing gap with sealing material in layers (4). First, fill the inner refractory fiber layer (41), then fill the middle layer of alumina hollow sphere castable layer (42), and finally fill the outer silicon carbide castable layer (43). Step 4: Install the cooling coil (2), so that the coil density of the cooling coil (2) gradually decreases from bottom to top along the axial direction, and connect the external cooling water inlet and outlet pipes (5).

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