A vaporization furnace for preparing nanoscale spherical silica powder

Abstract

This invention relates to a vaporization furnace for preparing nanoscale spherical silica powder. The vaporization furnace includes: a furnace body with an internal cavity; a burner located at the bottom of the internal cavity for generating a high-temperature flame; and an exhaust port located at the top of the internal cavity, connected to a condenser via a delivery pipe. This invention places the burner for heating the material at the bottom of the furnace body, feeding and heating the material at the bottom for vaporization. The vaporized silica rises and is discharged from the top of the furnace body to the condenser for rapid cooling, thus facilitating the formation of nanoscale silica particles. Compared to existing high-temperature melting furnaces, this invention produces fewer solid silica particles discharged from the vaporization furnace. During the ascent, the solid silica is more likely to sink under its own gravity and be re-vaporized by the burner, increasing the purity of the silica vapor cooled in the condenser and thus increasing the final yield of nanoscale spherical silica.

Description

Technical Field

[0001] This invention relates to the field of silica preparation technology, and specifically to a vaporization furnace for preparing nanoscale spherical silica powder. Background Technology

[0002] Nano-spherical silica mainly refers to silica powder with a D50 of less than 1 micrometer, where each particle is spherical. Due to its small particle size and high sphericity, it also possesses low expansion coefficient, high chemical and physical stability, low water absorption, high filling capacity, low forming stress, low friction, and good dielectric properties, making it irreplaceable in many industries and fields. Nano-spherical silica can be used as an additive, catalyst carrier, plastic filler, ink thickener, metal polishing agent, and insulating filler, and is widely used in integrated circuit packaging, copper-clad laminates, high-grade daily cosmetic fillers and spraying materials, pharmaceuticals, environmental protection, and other fields.

[0003] Currently, most commercially available nano-spherical silica is prepared using chemical methods, including precipitation, sol-gel, hydrolysis, and microemulsion methods. These methods are complex wet processes, presenting difficulties in solid-liquid separation. For example, directly drying nano-spherical silica particles results in a large number of hydroxyl groups on the surface, easily causing particle agglomeration and making dispersion difficult during use. Furthermore, their large specific surface area may lead to a porous structure and high oil absorption, making them unsuitable as fillers in epoxy systems. Conventional physical flame methods for preparing spherical silica involve placing the heating zone at the top of the furnace, allowing the silica to sink and naturally cool into spheres after heating. This results in insufficient purity of the heated silica vapor, often containing quartz powder that sinks due to gravity, leading to a low final content of nano-sized spherical silica. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a vaporization furnace for preparing nanoscale spherical silica powder.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A vaporization furnace for preparing nanoscale spherical silica powder, the vaporization furnace comprising:

[0007] The furnace body has an internal cavity.

[0008] A burner, located at the bottom of the inner cavity, is used to generate a high-temperature flame.

[0009] The inner cavity has an exhaust port at the top, and the exhaust port is connected to a condenser via a delivery pipe.

[0010] Furthermore, the furnace body includes an inner layer, a middle layer, and an outer layer arranged coaxially from the inside out;

[0011] The inner layer is made of corundum alumina and has a thickness of 250mm to 400mm.

[0012] The middle layer is made of insulating rock wool with a thickness of 200mm to 300mm;

[0013] The outer body is made of carbon steel protective layer.

[0014] Furthermore, the burner includes:

[0015] A flame diffuser is provided on the furnace body, and a combustion chamber is provided inside it;

[0016] A connecting portion, which is coaxially arranged with the flame diffuser and disposed at the bottom of the flame diffuser;

[0017] The combustion groove has a circular cross-section, and the diameter of the cross-section gradually increases along the axial direction away from the connecting part.

[0018] Furthermore, the connecting part is coaxially provided with a feeding pipe, a combustible gas pipe, a combustion-supporting gas pipe and a protective gas pipe from the inside to the outside.

[0019] The feeding pipe is used to transport oxygen and quartz powder; the combustible gas pipe is used to transport combustible gas; the combustion-supporting gas pipe is used to transport combustion-supporting gas; and the protective gas pipe is used to transport oxygen.

[0020] Furthermore, a bottom guide block is provided at the bottom of the inner layer body. The bottom guide block is an annular component with a trapezoidal cross-section. The burner is located at the center of the bottom guide block. A frustum-shaped bottom guide groove is provided at the upper end of the bottom guide block. The diameter of the upper cross-section of the bottom guide groove is larger than the diameter of the lower cross-section.

[0021] The inner layer is provided with a top guide block at the top. The top guide block is an annular part with a triangular cross-section. The exhaust port is located at the center of the top guide block. The center of the top guide block is provided with a frustum-shaped top guide groove. The diameter of the lower cross-section of the top guide groove is larger than the diameter of the upper cross-section.

[0022] Furthermore, the furnace body is provided with a protective section; the protective section includes a plurality of protective air passage components, wherein at least three of the protective air passage components are disposed at the same height of the furnace body, and the protective air passage components disposed at the same height are evenly distributed in a ring to form a ring protection group, and a plurality of the ring protection groups are arranged vertically on the furnace body.

[0023] Furthermore, the protective airway assembly includes a protective guide groove disposed on the inner wall of the inner layer, a first connecting pipe disposed on the inner layer, a second connecting pipe disposed on the outer layer, and a connecting pipe disposed in the middle layer.

[0024] One end of the connecting pipe is connected to the protective guide groove through the first connecting pipe, and the other end is connected to the external air supply device through the second connecting pipe.

[0025] The protective guide groove, the first connecting pipe, and the connecting pipe extend in a spiral shape on the outside of the inner cavity, and the protective guide groove, the first connecting pipe, and the connecting pipe are arranged sequentially from high to low.

[0026] Furthermore, the first connecting pipe is disposed through the inner layer, and the axis of the port where the first connecting pipe connects to the protective guide groove is tangent to the circular cross-section of the inner cavity.

[0027] Furthermore, the first connecting pipe includes a guide section and a connecting section connected in sequence; the guide section is connected to the protective guide groove, and the axis of the guide section is tangent to the circular cross-section of the inner cavity; the connecting section is connected to the connecting pipe.

[0028] Furthermore, the protective guide groove extends spirally along the axial direction of the inner layer body, and the edge of the protective guide groove is also provided with a guide groove wall at the position corresponding to the first connecting pipe. The guide groove wall extends obliquely from the bottom of the protective guide groove towards the inner wall of the inner layer body.

[0029] Compared with the prior art, the advantages of the present invention are:

[0030] The vaporization furnace of this invention differs from existing high-temperature melting furnaces that use flames to form spheres. In this furnace, the burner for heating the material is located at the bottom of the furnace body. The material is fed and heated at the bottom for vaporization, causing the vaporized silica to rise and be discharged from the top of the furnace body to a condenser for rapid cooling, thus facilitating the formation of nano-sized silica particles. Compared to existing high-temperature melting furnaces, this invention produces fewer solid silica particles discharged from the vaporization furnace. During the ascent, the solid silica is more likely to sink under its own gravity and be re-vaporized by the burner, increasing the purity of the silica vapor cooled in the condenser and thereby increasing the final yield of nano-sized spherical silica. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of the device for preparing nano-spherical silica powder;

[0032] Figure 2 This is a schematic diagram of the gasification furnace.

[0033] Figure 3 This is a cross-sectional view of the burner;

[0034] Figure 4 This is a top view of the burner;

[0035] Figure 5 yes Figure 2 AA view;

[0036] Figure 6 This is a schematic diagram of a bag filter dust collector;

[0037] Figure 7 This is a schematic diagram of the connection structure between the water curtain capture component and the bag capture component;

[0038] Figure 8 This is a schematic diagram of the connection structure of the central tube;

[0039] Figure 9 This is a SEM image of spherical silica collected by the bag filter in Example 1;

[0040] Figure 10 This is a SEM image of spherical silica collected by the bag filter in Example 2.

[0041] in:

[0042] 1-Gasification furnace; 2-Condenser; 3-Cyclone collector; 4-Bag filter; 5-Exhaust fan; 11-Inner layer; 12-Middle layer; 13-Outer layer; 14-Protective part; 15-Burner; 16-Exhaust port; 41-Shell; 42-Water curtain capture assembly; 43-Bag filter assembly; 44-Airflow outlet; 45-Box; 46-Guide baffle; 47-Airflow inlet; 48-Water storage chamber; 49-Water filter; 50-Water supply pipe; 111-Bottom guide block; 112-Top guide block; 141-Protective guide groove; 142-First connecting pipe; 143-Second connecting pipe; 144-Connecting pipe; 151 - Connecting part; 152 Flame expander; 153 Combustion tank; 154 Feeding pipe; 155 Combustible gas pipe; 156 Combustion-supporting gas pipe; 157 Protective gas pipe; 421 Central pipe; 422 Water storage disc; 423 Limiting ring; 424 Water curtain pipe body; 425 Collecting block; 426 Overflow port; 427 Limiting block; 428 Outlet hole; 431 Dust collector bag; 432 Support frame; 433 Fixing seat; 434 Sealing plate; 1411 Guide groove wall; 1421 Guide section; 1422 Connecting section; 4211 Fixing section; 4212 Snap-fit ​​section; 4213 Fixing block. Detailed Implementation

[0043] The present invention will be further described below with reference to the accompanying drawings:

[0044] Example 1

[0045] The present invention comprises a vaporization furnace and condenser, a cyclone collector, a bag filter, and an induced draft mechanism for preparing nano-spherical silica powder, and uses this device to prepare nano-spherical silica powder. Figure 1 This is a schematic diagram of the apparatus for preparing the nano-spherical silica powder. Figure 1 As shown, the apparatus for preparing the nano-spherical silica powder includes a vaporization furnace 1, a condenser 2, a cyclone collector 3, a bag filter 4, and an induced draft fan 5 connected in sequence. A burner is installed at the bottom of the vaporization furnace 1, and the upper end of the vaporization furnace 1 is connected to the condenser 2 via a conveying pipe. A temperature monitor is installed inside the vaporization furnace 1. The condenser 2, the cyclone collector 3, the bag filter 4, and the induced draft fan 5 are connected in sequence. A combustion control system is connected to the burner and the temperature monitor to control the combustion temperature of the burner, thereby controlling the temperature inside the vaporization furnace 1.

[0046] like Figure 2 As shown, the vaporization furnace 1 includes a furnace body. The furnace body has a cylindrical inner cavity, and a burner 15 is located at the bottom of the inner cavity. An exhaust port 16 is located at the top of the inner cavity, and the exhaust port 16 is connected to a condenser 2 via a delivery pipe. The burner 15 generates a high-temperature flame with a temperature greater than 3000℃. The furnace body includes an inner layer 11, a middle layer 12, and an outer layer 13. The inner layer 11 is made of corundum alumina material with a thickness of 250mm to 400mm. The middle layer 12 is made of insulating rock wool with a thickness of 200mm to 300mm. The outer layer 13 is made of carbon steel with a protective layer. A protective section 14 is provided on the arc-shaped surface of the furnace body corresponding to the inner cavity to reduce the contact between silica vapor and the inner wall of the furnace body.

[0047] The vaporization furnace 1 in this invention differs from existing high-temperature melting furnaces that use flame-forming spherical particles. The burner 15, which heats the material, is located at the bottom of the furnace body. Vaporization is achieved through bottom feeding, causing the vaporized silica to rise and be discharged from the top of the furnace body to the condenser 2 for rapid cooling, thus facilitating the formation of nano-sized silica particles. Compared to existing high-temperature melting furnaces, this invention produces fewer solid silica particles discharged from the vaporization furnace 1. During the rising process, the solid silica is more likely to sink under its own gravity and be re-vaporized by the burner 15, increasing the purity of the silica vapor cooled in the condenser 2 and thus increasing the final yield of nano-sized spherical silica. Furthermore, the flame temperature of the burner 15 is much higher than the boiling point of quartz (2230°C), ensuring that the overall temperature inside the cavity remains above 2230°C, guaranteeing that the silica within the cavity is in an optimal vaporization state.

[0048] like Figure 3 and Figure 4 As shown, the burner 15 includes a connecting portion 151 and a flame diffuser 152. The flame diffuser 152 is fixedly mounted on the furnace body, and the connecting portion 151 is fixedly mounted at the bottom of the flame diffuser 152. The connecting portion 151 and the flame diffuser 152 are coaxially arranged. A combustion groove 153 is provided inside the flame diffuser 152. The cross-section of the combustion groove 153 is circular, and the diameter of the cross-section of the combustion groove 153 gradually increases in the direction away from the axis of the connecting portion 151, so as to form a combustion flame with a better shape. A feeding pipe 154 is axially arranged at the center of the connecting portion 151. A combustible gas pipe 155, an auxiliary gas pipe 156, and a protective gas pipe 157 are arranged sequentially from the inside to the outside of the connecting portion 151 with the feeding pipe 154 as the center. The combustible gas pipeline 155, the combustion-supporting gas pipeline 156, and the protective gas pipeline 157 are all configured as annular grooves, and are coaxially arranged. The feeding pipeline 154 is used to transport oxygen and quartz powder, the combustible gas pipeline 155 is used to transport combustible gas, the combustion-supporting gas pipeline 156 is used to transport combustion-supporting gas, and the protective gas pipeline 157 is used to transport oxygen.

[0049] The burner 15, through the aforementioned structural arrangement, ensures that the combustion-supporting gas and oxygen in the protective gas pipe 157 and the combustion-supporting gas pipe 156 enter the combustion chamber 153 more evenly. The quartz powder must move outwards from the center of the combustion flame to achieve complete combustion. The oxygen in the protective gas pipe forms a barrier within the combustion chamber 153, preventing molten particles from adhering to the chamber wall. Simultaneously, due to the centralized arrangement of the feeding pipe 154, the combustible gas pipe 155, the combustion-supporting gas pipe 156, and the protective gas pipe 157, the quartz powder is also "atomized" under the impact of the gases discharged from the combustible gas pipe 155, the combustion-supporting gas pipe 156, and the protective gas pipe 157 during its movement. This effectively prevents particles from sticking together, allowing each "quartz glass droplet" to form an independent sphere, reducing the generation of large particles and particle size drift.

[0050] To facilitate the connection of each pipe to the outside, the connecting part 151 includes a plurality of cylindrical connecting blocks that are fixedly connected in sequence. The connecting blocks are coaxially arranged, and the diameter of each connecting block decreases in sequence along the direction away from the flame diffuser 152, thereby forming a plurality of protrusions on the connecting part 151. Each connecting block has a connection interface on its outer circular surface to correspond to different pipes, so as to realize the connection between different pipes and each gas supply component. While reducing the weight of the burner 15, the distance between the innermost combustible gas pipe 155 and the corresponding connection interface can also be minimized.

[0051] The burner 15 of the present invention can adjust the length of the combustion flame by adjusting the flow rate of combustible gas and the flow rate of combustion-supporting gas, so that all the powder particles are melted into gas. It can also adjust the residence time of quartz powder particles in the flame by adjusting the flow rate of quartz powder. Using oxygen to transport raw materials can maintain a full oxygen atmosphere and improve combustion efficiency.

[0052] The inner layer 11 is provided with a bottom guide block 111 corresponding to the burner 15. The bottom guide block 111 is a ring-shaped part with a trapezoidal cross-section. The burner 15 is located at the center of the bottom guide block 111. The upper end of the bottom guide block 111 is provided with a cylindrical frustum-shaped bottom guide groove. The diameter of the upper cross-section of the bottom guide groove is larger than the diameter of the lower cross-section, so that the upper end of the bottom guide block 111 is inclined towards the center to avoid the accumulation of solid quartz powder in the furnace body. Under the action of its own gravity, the solid quartz powder will gather towards the burner 15 at the inclined end of the bottom guide block 111 to achieve complete combustion and vaporization.

[0053] The inner layer 11 is provided with a top guide block 112 at the top of the furnace body. The top guide block 112 is a ring-shaped part with a triangular cross-section. The exhaust port 16 is located at the center of the top guide block 112. The center of the top guide block 112 is provided with a cylindrical frustum-shaped top guide groove. The diameter of the lower cross-section of the top guide groove is larger than the diameter of the upper cross-section, so that the inner wall of the top guide block 112 is inclined towards the center, which facilitates the smooth discharge of silica vapor in the inner cavity through the exhaust port 16.

[0054] The protection section 14 includes a plurality of protective gas duct assemblies. At least three of the protective gas duct assemblies are arranged at the same height on the furnace body, and the protective gas duct assemblies arranged at the same height are evenly distributed in a ring to form a ring protection group. A plurality of the ring protection groups are arranged vertically on the furnace body. Gas is introduced through the protective gas duct assemblies to form a gas circulation on the inner wall of the furnace, thereby reducing the contact between silica vapor and the inner layer 11.

[0055] like Figure 5 As shown, the protective airway assembly includes a protective guide groove 141, a first connecting pipe 142, a second connecting pipe 143, and a connecting pipe 144. The protective guide groove 141 is disposed on the inner wall of the inner layer 11. The first connecting pipe 142 is fixedly disposed on the inner layer 11, and the second connecting pipe 143 is fixedly disposed on the outer layer 13. The connecting pipe 144 is fixedly disposed in the middle layer 12, one end of the connecting pipe 144 is connected to the protective guide groove 141 through the first connecting pipe 142, and the other end of the connecting pipe 144 is connected to an external air supply device through the second connecting pipe 143. The protective guide groove 141, the first connecting pipe 142, and the connecting pipe 144 extend spirally as a whole outside the inner cavity, and are arranged sequentially from high to low.

[0056] The structure of the protective gas duct assembly is such that while a protective gas layer is formed on the inner wall of the inner body 11, the protective gas layer flows in a spiral shape, thereby providing a certain upward support for the silica vapor in the furnace body, facilitating the discharge of the silica vapor from the exhaust port 16, and accelerating the movement speed of the silica vapor towards the condenser 2.

[0057] The first connecting pipe 142 penetrates the inner layer 11, and the port axis of the first connecting pipe 142 connected to the protective guide groove 141 is tangent to the circular cross-section of the inner cavity, reducing the disturbance of silica vapor in the inner cavity by the gas discharged from the first connecting pipe 142. At the same time, the setting of the protective guide groove 141 is also more conducive to forming a protective gas layer on the inner wall of the inner layer 11.

[0058] Preferably, the first connecting pipe 142 includes a guide section 1421 and a connecting section 1422 connected to each other. The guide section 1421 is connected to the protective guide groove 141, and the axis of the guide section 1421 is tangent to the circular cross-section of the inner cavity. The connecting section 1422 is connected to the connecting pipe 144 to ensure a slow transition from the connecting pipe 144 to the guide section 1421.

[0059] The connecting pipe 144 is embedded in the middle layer 12, and due to the spiral extension, the overall length of the connecting pipe 144 is relatively long, which facilitates the increase of the gas temperature in the connecting pipe 144 in the furnace body and avoids the influence of the protective gas layer temperature on the silica vapor.

[0060] Preferably, the second connecting pipe 143 is connected to an external gas supply device via a heat exchange pipe. The heat exchange pipe is wound around the conveying pipe between the exhaust port 16 and the condenser 2, and exchanges heat with the silica vapor in the conveying pipe, thereby further ensuring the temperature of the protective gas layer delivered to the inner cavity. It is worth noting that heat exchange can also be performed directly with the silica vapor in the condenser 2.

[0061] The protective guide groove 141 extends spirally along the inner layer 11, and the edge of the protective guide groove 141 is provided with a guide groove wall 1411 at the position corresponding to the first connecting pipe 142. The guide groove wall 1411 extends obliquely from the bottom of the protective guide groove 141 towards the inner wall of the inner layer 11, so as to form a protective air layer that fits the inner wall of the inner layer 11.

[0062] like Figure 6 As shown, the bag filter 4 includes a housing 41, a water curtain capture assembly 42, and a bag capture assembly 43. The housing 41 includes an airflow outlet 44, a box 45, a baffle 46, and an airflow inlet 47. The baffle 46 is disposed inside the box 45, and the baffle 46 divides the interior of the housing 41 into an upper cavity and a lower cavity. The upper cavity and the lower cavity are connected by the bag capture assembly 43. The airflow outlet 44 is located at the upper part of the box 45 and is connected to the lower cavity. The upper cavity is connected, and the airflow inlet 47 is located at the lower part of the housing 45 and is connected to the lower cavity. The bag capture assembly 43 is fixed inside the housing 45 by the guide baffle 46. The water curtain capture assembly 42 is fixed inside the bag capture assembly 43. Gas containing nano-sized spherical silica enters the housing 45 through the airflow inlet 47 and is discharged from the airflow outlet 44 under the filtration of the water curtain capture assembly 42 and the bag capture assembly 43.

[0063] The bottom of the housing 45 is provided with a water storage chamber 48. The lower end of the water supply pipe 50 is connected to the water storage chamber 48, and the upper end of the water supply pipe 50 is connected to the water curtain capture assembly 42. A circulating water pump is provided on the water supply pipe 50. The water in the water storage chamber 48 is powered by the circulating water pump and flows through the water supply pipe 50 to the water curtain capture assembly 42 to form a water curtain to capture particles containing silica gas.

[0064] A water filter 49 is provided inside the water storage chamber 48. The water filter 49 divides the water storage chamber 48 into a dust-containing water chamber and a filtered water chamber, which are arranged vertically. The dust-containing water chamber is located above the filtered water chamber. The lower end of the water supply pipe 50 is connected to the filtered water chamber. The water filter 49 reduces the amount of silica particles entering the water circulation.

[0065] Generally, the bottom of the housing 41 is provided with an outlet, the lower end of the water supply pipe 50 is provided with a flow regulating valve, the water supply pipe 50 is connected to the water inlet pipe, and a water valve is provided on the water inlet pipe. The flow regulating valve can open or close the water supply pipe 50 or adjust the water supply speed of the water supply pipe 50 to the water curtain capture component 42. The outlet is used to discharge all the water in the water storage chamber 48, the water inlet pipe is used to provide new water to the water supply pipe 50, and the water valve is used to open or close the water inlet pipe.

[0066] The water filter screen 49 is detachable or rotatable. When collecting silica, the water in the water storage chamber 48 is drained first, and the flow regulating valve and the water valve are closed. The water filter screen 49 is then detached or rotated, so that the silica particles of the water filter screen 49 are accumulated at the outlet and collected and discharged.

[0067] Since this invention uses a physical flame combustion method to produce spherical silica, even with the condenser 2 in the middle for cooling and spheroidization, the discharged gas containing silica particles still has a high temperature. Conventional cyclone collectors 3 use wind-driven settling to separate solid particles, so the cyclone collector 3 does not have high requirements for gas temperature. However, for conventional bag filters, the operating temperature of high-temperature dust collector bags is generally between 160℃ and 260℃. Therefore, this invention improves the corresponding structure for capturing particles by setting the water curtain capture component 42 and the water storage chamber 48. While the water curtain capture component 42 captures nano-sized spherical silica particles, the water flow under its own gravity and the water in the water storage chamber 48 can cool the gas that has just entered the lower chamber, effectively reducing the gas temperature in the housing 45, thus ensuring the working environment of the bag capture component 43 and improving the service life of the dust collector bags.

[0068] like Figure 7As shown, the bag filter assembly 43 includes a support frame and a dust collector bag 431. The dust collector bag 431 is fixedly sleeved on the outside of the support frame. The water curtain filter assembly 42 is disposed inside the support frame. The support frame includes a cylindrical support main frame 432. The support main frame 432 is provided with several ventilation holes to allow gas to pass from the inside of the support frame through the dust collector bag 431 to the outside. One end of the support main frame 432 is provided with a fixed seat 433, and the other end is provided with a circular sealing plate 434. The sealing plate 434 seals one end of the support frame. The support frame is fixedly mounted on the flow guide baffle 46 through the fixed seat 433. The flow guide baffle 46 is provided with a flow hole corresponding to the end of the support frame, so that the gas in the lower cavity can enter the inside of the support frame through the flow hole. Generally, the fixed seat 433 is set as an annular shape and is fixedly sleeved on the end of the support frame.

[0069] The water curtain capture assembly 42 includes a central tube 421, a water storage disc 422, a limiting ring 423, a water curtain tube body 424, and a collecting block 425. The water curtain tube body 424 is a cylindrical tubular component. The water storage disc 422 is fixedly installed at the upper end of the water curtain tube body 424, and the collecting block 425 is fixedly installed at the lower end of the water curtain tube body 424. The limiting ring 423 is fixedly installed on the inner wall of the support frame corresponding to the water storage disc 422. The central tube 421 is fixedly installed on the sealing plate 434, and one end of the central tube 421 is vertically fixed on the water storage disc 422. An annular overflow port 426 is formed between the limiting ring 423 and the water storage disc 422. The water flow from the water storage disc 422 flows through the overflow port 426 to the outer surface of the water curtain tube body 424, thereby forming a continuous and uniformly distributed water film.

[0070] Preferably, the central tube 421, the water storage disc 422, the limiting ring 423, the water curtain pipe body 424, the collecting block 425, and the support frame are all coaxially arranged, and the maximum diameter of the cross-section of the water storage disc 422, the water curtain pipe body 424, and the collecting block 425 is the same, thereby ensuring that a uniformly distributed water film is formed on the outside of the water curtain capture assembly 42.

[0071] When gas enters the support frame, it flows through the annular space between the water curtain pipe 424 and the support frame and passes through the dust collector bag 431. During the flow in the annular space, the gas comes into contact with the surface of the water film, which allows the water film to capture the silica particles in the gas. The captured silica moves downward along the water film and eventually collects in the water storage chamber 48, and is filtered by the water filter screen 49. The silica particles remain on the water filter screen 49.

[0072] This invention greatly improves the collection efficiency of nano-sized silica particles in the gas by using the dry and wet dual particle capture of the bag capture component 43 and the water curtain capture component 42. At the same time, the particles are collected in a concentrated manner by water flow, avoiding dust generation of nano-sized silica during recycling. The final nano-sized silica particles can be obtained by evaporating the silica liquid containing the particles.

[0073] Preferably, the central tube 421 is axially arranged at the center of the sealing plate 434, and the central tube 421 passes through and is fixedly arranged on the sealing plate 434. The end of the central tube 421 connected to the water storage disc 422 is radially provided with a plurality of outflow holes 428. The upper end of the central tube 421 is arranged corresponding to the outlet of the water supply pipe 50. The water in the water supply pipe 50 enters the interior of the central tube 421 through the outlet and flows to the water storage disc 422 through the outflow holes 428.

[0074] Generally, the water storage disc 422 is disc-shaped, and an annular limiting block 427 is provided on the upper surface of the water storage disc 422. The limiting block 427 and the water storage disc 422 are coaxial. The limiting block 427 limits the water storage space on the upper surface of the water storage disc 422. The water flowing out of the central pipe 421 gathers in the water storage space. After gathering to a certain volume, the liquid level in the water storage space is higher than the upper edge of the limiting block 427, thereby forming a water film along the outer wall of the limiting block 427 through the overflow port 426 to the water curtain pipe body 424.

[0075] Preferably, the cross-section of the limiting block 427 is set as a triangle, and the bottom edge of the cross-section of the limiting block 427 is attached and fixed to the upper surface of the water storage disc 422, so that the inner wall and the outer wall of the limiting block 427 are both set as inclined surfaces to facilitate the overflow of water.

[0076] The limiting ring 423 is configured in the shape of a trumpet, with the upper diameter of the limiting ring 423 being larger than the lower diameter. The upper end of the limiting ring 423 is fixedly connected to the inner wall of the support frame, and the lower end of the limiting ring 423 is disposed corresponding to the outer wall of the limiting block 427. A gap is provided between the lower end of the limiting ring 423 and the outer wall of the limiting block 427, and the gap is the overflow port 426.

[0077] The overflow port 426 is formed by the structure of the limiting ring 423 and the water storage disc 422. During operation, the overflow port 426 is submerged in water, forming a watertight structure, thereby preventing dust-laden gas from entering the upper end of the bag filter assembly 43.

[0078] Preferably, the collecting block 425 is cone-shaped, and the circular bottom of the collecting block 425 is fixedly disposed at the bottom end of the water curtain pipe 424, so that the water in the water film can be collected and flow down at the tip of the collecting block.

[0079] like Figure 8 As shown, the sealing plate 434 has a connecting hole at its center, which is a threaded hole. Correspondingly, the outer surface of the central tube 421 has an external thread. The central tube 421 and the connecting hole are threadedly connected, thereby enabling quick disassembly between the water curtain capture assembly 42 and the bag capture assembly 43.

[0080] To achieve precise alignment of the limiting ring 423 and the limiting block 427 and control the size of the overflow port 426, the central tube 421 includes a fixed section 4211 and a snap-fit ​​section 4212. The cross-sectional diameter of the fixed section 4211 is smaller than that of the snap-fit ​​section 4212. The fixed section 4211 is provided with external threads. The fixed section 4211 is connected to the sealing plate 434. The upper end of the snap-fit ​​section 4212 is snapped and positioned with the sealing plate 434, thereby ensuring that the limiting ring 423 and the limiting block 427 can be precisely aligned after each disassembly.

[0081] Similarly, a fixing block 4213 is threadedly connected to the fixing section 4211. The fixing block 4213 is positioned above the sealing plate 434. By fitting the fixing block 4213 and the sealing plate 434 together, the connection stability between the central tube 421 and the sealing plate 434 is enhanced. At the same time, the size of the overflow port 426 can be adjusted in real time by adjusting the position of the central tube 421 and fixing the central tube 421 with the fixing block 4213.

[0082] The preparation method for preparing nano-spherical silica powder using the above-mentioned preparation device is as follows:

[0083] S1. Combustible gas and combustion-supporting gas are mixed and burned in a burner located inside the vaporization furnace 1. The mixed combustion in the vaporization furnace 1 produces a high-temperature flame with a temperature greater than 3000°C and an outer flame temperature greater than 2500°C.

[0084] S2. Quartz powder is fed into a high-temperature flame through a feeding pipe, where it undergoes a solid-liquid-gas transformation to become silica vapor.

[0085] S3. Start the induced draft fan 5. A negative pressure is generated in the vaporization furnace 1. Under the action of the negative pressure, the silica vapor enters the condenser 2 along the conveying pipe and is rapidly cooled in the condenser 2, changing from a gaseous state to a solid state to form spherical silica particles.

[0086] S4. The spherical nano-silica particles in the condenser 2 are moved to the collection section by the induced draft fan 5, and the collection section collects the spherical silica particles.

[0087] Preferably, in step S1, the calorific value of the combustible gas is higher than 12500 Kcal / Nm3, and the combustion-supporting gas is oxygen with a purity greater than 99%.

[0088] The flow rate of the combustible gas in the burner is 50 m³ / h to 250 m³ / h, and the flow rate of the combustion-supporting gas is 100 m³ / h to 500 m³ / h.

[0089] Preferably, the median particle size of the quartz powder is set to 5μm to 30μm, the maximum particle size is not greater than 100μm, and the feeding rate of the quartz powder is 50kg / h to 200kg / h.

[0090] In step S2, the quartz powder is added to the vaporization furnace 1 from the center of the burner using oxygen as the transport gas, with the transport gas pressure set to 0.3 MPa to 0.6 MPa. Since inert gases do not participate in combustion, this invention uses oxygen to transport the raw material, which avoids the inert gas from disrupting the normal distribution of flame temperature, increases the pelletizing rate, reduces the influence of the transport medium on the flame morphology and flame temperature, and simultaneously reduces the contamination of silica particles by impurities.

[0091] Generally, the cooling capacity of the condenser 2 is not less than 200kw; the induced draft fan 5 is a variable frequency fan with a power of 110kw to 160kw.

[0092] Preferably, the particle size of the final nanoparticles is controlled by controlling the cooling rate of the condenser 2. When the cooling rate of the condenser 2 is set to 100℃ / s to 200℃ / s, the particle size of the nano-sized spherical silica particles is 50 nanometers to 1500 nanometers; when the cooling rate of the condenser 2 is set to 200℃ / s to 400℃ / s, the particle size of the nano-sized spherical silica particles is 20 nanometers to 1000 nanometers.

[0093] The collection section includes a cyclone collector 3 and a bag filter 4. The cyclone collector 3 is connected to the condenser 2. The bag filter 4 is disposed between the cyclone collector 3 and the induced draft fan 5. The cyclone collector 3 is used to collect μm-sized spherical silica particles, and the bag filter 4 is used to collect nano-sized spherical silica particles.

[0094] In step S1, the gasification furnace 1 includes an inner layer, a middle layer, and an outer layer. The inner layer is made of corundum alumina with a thickness of 250mm to 400mm, the middle layer is made of insulating rock wool with a thickness of 200mm to 300mm, and the outer layer is made of carbon steel protective layer.

[0095] It is worth noting that during the process of transporting silicon dioxide from the vaporization furnace 1 to the condenser 2, an auxiliary heating device can be added to heat and maintain the silicon dioxide temperature, thereby ensuring that the silicon dioxide remains in a gaseous state throughout the process from the vaporization furnace 1 to the condenser 2. The auxiliary heating device can be an existing conventional heating method such as installing heating pads in the conveying pipeline or an auxiliary heating furnace.

[0096] This invention controls the particle size of the final spherical nano-silica by adjusting factors such as flame temperature, feed particle size, and cooling rate to control the growth of silica grains. A high proportion of nano-sized spherical silica is obtained by vaporizing quartz powder with a high-temperature flame exceeding 3000℃ and then cooling it. Furthermore, this invention employs a dry process, which is simple in route, easy to control, and allows for continuous production, with output sufficient for industrial-scale production. This invention also significantly increases the amount of nano-sized silica solid particles generated by directly heating solid quartz powder to form gaseous silica gas, and then directly condensing the gaseous silica into spherical silica solid particles in a condenser, thereby producing a large quantity of nano-spherical silica powder.

[0097] In this embodiment, the vaporization furnace 1 has a height of 6 meters and an effective diameter of 1200 mm. Four infrared thermometers are evenly distributed in the vaporization furnace 1 to measure the temperature of the outer flame. The combustion control system adjusts the flow rate of fuel gas and oxygen through temperature feedback.

[0098] The inner layer of the gasifier is made of alumina bricks with a thickness of 300 mm, the middle layer is made of insulating rock wool with a thickness of 200 mm, and the outer layer is a carbon steel protective layer. The burner is located at the bottom of the gasifier 1, and the material outlet is located at the top of the gasifier 1.

[0099] The induced draft fan 5 has a power of 132 kW. When the induced draft fan 5 is started, the frequency converter frequency is 45 Hz, generating negative pressure in the entire process piping system, with the pressure controlled at -1.5 kPa. The condenser 2 is then started, with a cooling capacity of 200 kW; the cooling rate of the condenser 2 is set to 200 °C / s.

[0100] The burner is started, using acetylene as fuel and oxygen (purity greater than 99%) as combustion-supporting gas. The mixture is mixed in an oxygen-fuel burner and burned in the vaporization furnace 1 to produce a high-temperature flame with an outer flame temperature of 2500°C and an inner flame temperature of 3100°C.

[0101] Using crystalline quartz powder as raw material, with a D50 of 5 μm, a maximum particle size of less than 30 μm, a SiO2 content of 99.81%, and a specific surface area of ​​3.1 m² / g, the crystalline quartz powder is fed into the vaporization furnace 1 through the feeding pipe using oxygen with a purity of not less than 99% as the transport gas. Since the flame temperature is much higher than the boiling point of quartz (2230℃), the quartz powder absorbs heat in the flame and instantly completes the solid-liquid-gas transformation, becoming silica vapor.

[0102] Under negative pressure, silica vapor enters the condenser 2 through the conveying pipe, where it is rapidly cooled and changes from a gaseous state to a solid state, forming spherical nano-silica particles.

[0103] The cyclone collector 3 collects μm-sized spherical silica with a D50 of 3μm, while the bag filter 4 collects nano-sized spherical silica with a D50 of 0.4μm, a maximum particle size of 0.9μm, a SiO2 content of 99.72%, and a specific surface area of ​​23.1m2 / g.

[0104] Figure 9 This is a SEM image of spherical silica collected by the bag filter 4 in this embodiment. Figure 9 It is clear that, except for a very small number of spherical silica particles with a particle size of nearly 1 μm, most spherical silica particles are in the nanometer range.

[0105] Example 2

[0106] In this embodiment, the vaporization furnace 1 has a height of 6 meters and an effective diameter of 1200 mm. Four infrared thermometers are evenly distributed in the vaporization furnace 1 to measure the temperature of the outer flame. The combustion control system adjusts the flow rate of fuel gas and oxygen through temperature feedback.

[0107] The inner layer of the gasifier is made of alumina bricks with a thickness of 300 mm, the middle layer is made of insulating rock wool with a thickness of 200 mm, and the outer layer is a carbon steel protective layer. The burner is located at the bottom of the gasifier 1, and the material outlet is located at the top of the gasifier 1.

[0108] The induced draft fan 5 has a power of 132 kW. When the induced draft fan 5 is started, the frequency converter frequency is 30 Hz, generating negative pressure in the entire process piping system, with the pressure controlled at -0.9 kPa. The condenser 2 is then started, with a cooling capacity of 300 kW; the cooling rate of the condenser 2 is set to 320℃ / s.

[0109] The burner is started, using acetylene as fuel and oxygen (purity greater than 99%) as combustion-supporting gas. The mixture is mixed in an oxygen burner and burned in the vaporization furnace 1 to produce a high-temperature flame with an outer flame temperature of 2700°C and an inner flame temperature of 3300°C.

[0110] Using crystalline quartz powder as raw material, with a D50 of 15 μm, a maximum particle size of less than 60 μm, a SiO2 content of 99.83%, and a specific surface area of ​​1.2 m² / g, the crystalline quartz powder is fed into the vaporization furnace 1 through the feeding pipe using oxygen with a purity of not less than 99% as the transport gas. Since the flame temperature is much higher than the boiling point of quartz (2230℃), the quartz powder absorbs heat in the flame and instantly completes the solid-liquid-gas transformation, becoming silicon dioxide vapor.

[0111] Under negative pressure, silica vapor enters the condenser 2 through the conveying pipe, where it is rapidly cooled and changes from a gaseous state to a solid state, forming spherical nano-silica particles.

[0112] The cyclone collector 3 collects μm-sized spherical silica with a D50 of 2μm, while the bag filter 4 collects nano-sized spherical silica with a D50 of 0.2μm, a maximum particle size of 0.8μm, a SiO2 content of 99.65%, and a specific surface area of ​​32.6m2 / g.

[0113] Everything else is the same as in Example 1.

[0114] Figure 10 This is a SEM image of spherical silica collected by the bag filter 4 in this embodiment. Figure 10 It is clearly visible that all the spherical silica particles are nanoscale in size.

[0115] The above-described embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A vaporization furnace for preparing nanoscale spherical silica powder, characterized in that, The gasification furnace includes: The furnace body has an internal cavity. A burner, located at the bottom of the inner cavity, is used to generate a high-temperature flame. An exhaust port is provided at the top of the inner cavity, and the exhaust port is connected to a condenser via a delivery pipe. The furnace body includes an inner layer, a middle layer, and an outer layer arranged coaxially from the inside out; the furnace body is provided with a protective section; the protective section includes at least three protective gas duct assemblies, wherein at least three protective gas duct assemblies are arranged at the same height on the furnace body, and the protective gas duct assemblies arranged at the same height are evenly distributed in a ring to form a ring protection group, and multiple ring protection groups are arranged vertically on the furnace body; the protective gas duct assembly includes a protective guide groove provided on the inner wall of the inner layer, a first connecting pipe provided on the inner layer, a second connecting pipe provided on the outer layer, and a connecting pipe provided in the middle layer; one end of the connecting pipe is connected to the protective guide groove through the first connecting pipe, and the other end is connected to an external gas supply device through the second connecting pipe; the protective guide groove, the first connecting pipe, the second connecting pipe, the second connecting pipe, the third ... A connecting pipe and a communicating pipe extend spirally around the outside of the inner cavity, and the protective guide groove, the first connecting pipe, and the communicating pipe are arranged sequentially from high to low. The first connecting pipe passes through the inner layer, and the axis of the port where the first connecting pipe connects to the protective guide groove is tangent to the circular cross-section of the inner cavity. The first connecting pipe includes a guide section and a connecting section connected in sequence. The guide section is connected to the protective guide groove, and the axis of the guide section is tangent to the circular cross-section of the inner cavity. The connecting section is connected to the communicating pipe. The protective guide groove extends spirally along the axial direction of the inner layer, and the edge of the protective guide groove, in addition to the position corresponding to the first connecting pipe, is also provided with a guide groove wall. The guide groove wall extends obliquely from the bottom of the protective guide groove towards the inner wall of the inner layer.

2. The gasification furnace according to claim 1, characterized in that, The inner layer is made of corundum alumina and has a thickness of 250mm to 400mm. The middle layer is made of insulating rock wool with a thickness of 200mm to 300mm; the outer layer is made of carbon steel protective layer.

3. The gasification furnace according to claim 1, characterized in that, The burner includes: a flame diffuser disposed on the furnace body, with a combustion groove inside; and a connecting part coaxially disposed with the flame diffuser and disposed at the bottom of the flame diffuser; wherein the combustion groove has a circular cross-section, and the diameter of the cross-section gradually increases along the axial direction away from the connecting part.

4. The gasification furnace according to claim 3, characterized in that, The connecting section is coaxially arranged from the inside out with a feeding pipe, a combustible gas pipe, an auxiliary gas pipe, and a protective gas pipe; wherein, the feeding pipe is used to transport oxygen and quartz powder; the combustible gas pipe is used to transport combustible gas; the auxiliary gas pipe is used to transport auxiliary gas; and the protective gas pipe is used to transport oxygen.

5. The gasification furnace according to claim 1, characterized in that, The inner layer has a bottom guide block at its bottom, which is an annular component with a trapezoidal cross-section. The burner is located at the center of the bottom guide block. The upper end of the bottom guide block has a frustum-shaped bottom guide groove, the diameter of the upper cross-section of the bottom guide groove being larger than the diameter of the lower cross-section. The inner layer has a top guide block at its top, which is an annular component with a triangular cross-section. The exhaust port is located at the center of the top guide block. The center of the top guide block has a frustum-shaped top guide groove, the diameter of the lower cross-section of the top guide groove being larger than the diameter of the upper cross-section.

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