Synthetic quartz glass deposition furnace and dynamic environment control method thereof

Abstract

The invention relates to the technical field of quartz glass preparation, in particular to a synthetic quartz glass deposition furnace and a dynamic environment control method thereof. The deposition furnace comprises a furnace body, a furnace top, a blast burner, a rotary lifting crucible and a set of dynamic environment control system, and the system comprises a gas curtain generating device, an exhaust system capable of being independently controlled in a partitioned mode, a sensor array used for monitoring pressure and particulate matter concentration and a closed-loop feedback controller. The state in the furnace is monitored in real time through a sensor, particle aggregation is recognized through a control algorithm, and an exhaust system in a specific area is triggered to conduct fixed-point removal. And meanwhile, through cooperative compensation control, the stability of the pressure in the furnace can still be maintained when pollutants are removed. According to the method, the contradiction between the pollutant removal efficiency and the process environment stability is solved, the product defects can be effectively reduced, and the structural uniformity and the optical performance of the large-size synthetic quartz glass are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of quartz glass preparation technology, specifically to a deposition furnace and its control method capable of dynamic and precise control of the furnace environment, which is particularly suitable for preparing high-quality synthetic quartz glass. Background Technology

[0002] High-quality, large-size synthetic quartz glass, due to its extremely high purity, excellent optical transmittance (especially in the deep ultraviolet band), extremely low coefficient of thermal expansion, and outstanding chemical stability, is a key fundamental material for modern cutting-edge technologies. It is widely used in core components of the semiconductor industry, optics, laser technology, and aerospace. With the continuous improvement of chip manufacturing processes and laser power requirements due to technological advancements, unprecedentedly stringent requirements have been placed on the internal quality of synthetic quartz glass, especially its structural consistency and the uniformity of its optical refractive index.

[0003] Chemical vapor deposition (CVD) is the mainstream industrial method for preparing high-quality, large-size synthetic quartz glass. Its basic principle is as follows: a high-purity silicon-containing precursor is fed into an oxyhydrogen torch under a carrier gas, where it undergoes high-temperature hydrolysis and oxidation reactions in a flame at nearly 2000°C, generating nanoscale silicon dioxide (SiO2) particles. These incandescent microparticles move downwards and deposit on the surface of a high-temperature target in the center of the furnace chamber. Through continuous deposition and high-temperature melting, a dense synthetic quartz glass ingot is eventually formed.

[0004] However, a key technical challenge exists in this deposition process. In the complex high-temperature gas flow environment inside the furnace, not all generated SiO2 microparticles can successfully reach the target surface and be effectively deposited. Typically, about 15% to 40% of the microparticles will be suspended and drifting within the furnace cavity due to the convection and turbulence of the high-temperature gas. These suspended microparticles will continuously collide and adhere during circulation, gradually agglomerating into larger particles, and even sintering into macroscopic flake or flocculent deposits on the furnace top or walls.

[0005] These large, loose particles or deposits are the main cause of product defects. Once they detach due to gravity or airflow disturbance and fall onto the quartz glass growth interface, they will form macroscopic defects such as bubbles, solid inclusions, and streaks inside or on the surface. These defects severely disrupt the continuity and consistency of the quartz glass structure, leading to a decrease in its optical uniformity and potentially creating stress concentration points. Ultimately, this results in expensive product downgrading or scrapping, significantly impacting yield and economic benefits.

[0006] To address this issue, existing technologies typically incorporate exhaust vents on the furnace sidewalls to extract waste gas and suspended particles using negative pressure. However, the exhaust volume in these solutions is usually adjusted solely based on the negative pressure value, aiming to maintain a constant set pressure. This approach relies entirely on indirect pressure control, lacking real-time monitoring and diagnosis of particulate matter within the furnace. It cannot determine whether pressure fluctuations are caused by particle agglomeration or other disturbances, nor can it identify aggregated particles that do not cause significant pressure changes. More importantly, this pressure-feedback-based adjustment fails to address the interference of the exhaust process itself on the delicate furnace environment. For example, when a clump of particles passes through the exhaust vent, the system passively increases the exhaust volume. This global increase in negative pressure, in turn, leads to fluctuations in the pressure and temperature field throughout the furnace cavity. For large-size, high-quality quartz glass, such fluctuations in the process environment are a key technological bottleneck hindering the improvement of its optical uniformity. Therefore, existing technologies fundamentally fail to resolve the contradiction between contaminant removal efficiency and process environment stability. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a synthetic quartz glass deposition furnace and a dynamic environmental control method thereof, which can effectively discharge polluting particulate matter while maintaining the stability of the furnace environment to the maximum extent, thereby significantly improving the quality of synthetic quartz glass products.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: I. A Synthetic Quartz Glass Deposition Furnace The present invention provides a synthetic quartz glass deposition furnace, which mainly includes: a furnace body 100, a blowtorch 102 disposed on the furnace top 101, a rotating and lifting crucible 103 disposed in the middle of the furnace cavity, and a dynamic environmental control system. The furnace cavity is divided into multiple exhaust zones along the vertical height direction. The dynamic environment control system specifically includes: a gas curtain generating device 200 integrated and installed on the furnace top 101; an exhaust system 300 installed on the side wall of the furnace body 100 in each exhaust zone and can be controlled separately in each zone; a sensor array for collecting furnace environment information; and a closed-loop feedback controller 500 running a dynamic environment control program. The sensor array includes a particulate sensor 410 and a local pressure sensor 420 respectively disposed in each exhaust zone, and a global pressure sensor 430 disposed inside the furnace cavity. The gas curtain generating device 200, the exhaust system 300, the particulate matter sensor 410, the local pressure sensor 420, and the global pressure sensor 430 are all electrically connected to the closed-loop feedback controller 500.

[0009] Furthermore, an annular groove 201 is provided on the lower surface of the furnace top 101. The annular groove 201 is concentric with the central axis of the furnace top 101, and the radius R of the annular groove 201 and the radius r of the annulus containing the outermost torch 102 of the furnace top satisfy: 1.1r < R < 1.4r.

[0010] Furthermore, the gas curtain generating device 200 includes an annular hollow pipe assembly 210 fixedly installed in the annular groove 201. The annular hollow pipe assembly 210 is composed of an inner pipe 211 and an outer pipe 212. The inner pipe 211 is provided with a cooling medium circulation channel, and the cooling medium inlet and outlet of the cooling medium circulation channel are connected to the cooling circulation system outside the furnace. The outer pipe 212 coaxially covers the outer ring of the inner pipe 211, and an inert gas distribution and pressure storage cavity 213 is formed between the inner wall of the outer pipe 212 and the outer wall of the inner pipe 211. The lower wall of the outer pipe 212 is provided with a plurality of gas injection holes 214 that are connected to the inert gas distribution and pressure storage cavity 213 at equal intervals along the circumference.

[0011] Furthermore, the inert gas inlet of the inert gas distribution and storage chamber 213 is connected to the gas supply system outside the furnace through a gas pipeline 215. A mass flow controller 221 for controlling the inert gas flow rate and an online gas heater 222 for heating the inert gas to a preset temperature are connected in series on the gas pipeline 215. Both the mass flow controller 221 and the online gas heater 222 are electrically connected to the closed-loop feedback controller 500.

[0012] Furthermore, the number of exhaust zones is positively correlated with the inner diameter of the furnace cavity; the furnace sidewall of each exhaust zone is composed of an inner furnace wall 100a and an outer furnace wall 100b, and an annular flue 320 is formed between the inner furnace wall 100a and the outer furnace wall 100b, and the inner furnace wall 100a is uniformly provided with multiple exhaust ports 321 that are connected to the annular flue 320 in a circumferential direction.

[0013] Furthermore, the annular flue 320 is connected to the regional exhaust pipe 330 extending from the outer wall 100b of the furnace body. The regional exhaust pipe 330 is equipped with a particulate sensor 410 for real-time monitoring of silica particulate matter concentration in the airflow and a regional electric regulating valve 340 for controlling the exhaust volume of the area. Both the particulate sensor 410 and the regional electric regulating valve 340 are electrically connected to the closed-loop feedback controller 500.

[0014] Furthermore, the local pressure sensor 420 is used to measure the real-time pressure inside the furnace in the corresponding exhaust zone. Its pressure measuring point is inserted into the side wall of the furnace body through a pressure guiding pipe, and the opening of the pressure guiding pipe is flush with the inner wall 100a of the furnace body. The global pressure sensor 430 is used to measure the reference total pressure inside the furnace cavity. Its pressure measuring point is located on the lower surface of the furnace top 101 at a position away from the blowtorch 102.

[0015] II. A method for dynamic environmental control of a synthetic quartz glass deposition furnace Based on the same inventive concept, the present invention also provides a dynamic environmental control method for the synthetic quartz glass deposition furnace as described above, which mainly includes the following steps: S1, Particulate matter agglomeration identification and determination: The closed-loop feedback controller analyzes the signal correlation between the local pressure sensor and the particulate matter sensor in each exhaust zone to identify whether particulate matter agglomeration that needs to be dealt with has occurred in each exhaust zone. If so, proceed to step S2. S2, Exhaust system exhaust volume coordinated control: The closed-loop feedback controller sends a forced exhaust command to the regional electric regulating valve of the exhaust zone where particulate matter agglomerates, increasing the opening of the regional electric regulating valve of that exhaust zone from the initial degree to the forced exhaust opening, so as to capture and discharge the agglomerated particulate matter in that exhaust zone; at the same time, based on the feedback signal of the global pressure sensor, the closed-loop feedback controller sends a pressure compensation command to the regional electric regulating valve of the remaining exhaust zones, synchronously reducing the opening of the corresponding regional electric regulating valve by a preset amount, so as to stabilize the global pressure in the furnace within a preset range; S3, Dynamic control of gas curtain flow: The closed-loop feedback controller sends a dynamic adjustment command to the mass flow controller of the gas curtain generating device according to the current exhaust volume of each exhaust zone, so that the injection flow of inert gas is dynamically changed according to the opening of the regional electric regulating valve of each exhaust zone to maintain the stability of the gas curtain shape. S4, System Control Parameter Reset: The closed-loop feedback controller continuously monitors the particulate sensor signal in the exhaust zone where particulate matter agglomerates. When the particulate matter concentration returns to the baseline concentration range and remains there for a preset time period, the controller sends a reset command to the mass flow controller of the regional electric regulating valve and the gas curtain generating device in each exhaust zone, so that the system equipment can smoothly return to the initial setting state.

[0016] Furthermore, in step S1, the criteria for determining the occurrence of particulate matter agglomeration requiring treatment include: 1) Judgment condition one: The real-time pressure fluctuation amplitude detected by the local pressure sensor in the current exhaust zone exceeds the preset pressure fluctuation threshold. 2) Judgment condition two: The growth rate of silica particulate matter concentration in the exhaust pipe detected by the particulate matter sensor in the current exhaust zone exceeds the preset concentration growth rate threshold. When both judgment condition one and judgment condition two are satisfied, it is determined that particulate matter agglomeration requiring treatment has occurred in the current exhaust zone.

[0017] Furthermore, in step S3, the increase in the inert gas injection flow rate ΔL is proportional to the increase in the opening of the regional electric regulating valve in the exhaust zone where the particulate matter agglomerates ΔK.

[0018] Compared with the prior art, the present invention has the following main advantages: 1. This invention organically integrates a gas curtain generating device, a multi-zone exhaust system, a multi-dimensional sensor array, and a closed-loop feedback controller. Through the static pressure chamber design, it ensures the uniformity of suction within each exhaust zone. Relying on the particulate matter concentration monitor on the main exhaust pipe of each zone, it achieves accurate identification of the level of particulate matter agglomeration. At the same time, for the identified particulate matter agglomeration areas, the system performs an overall and uniform capture and removal operation, which can accurately locate and deal with particulate matter agglomeration problems, effectively reduce defects such as bubbles and solid phase inclusions caused by pollutants falling, and improve the product molding quality.

[0019] 2. This invention adopts a closed-loop control logic of collaborative compensation to dynamically regulate the pressure field inside the furnace during the exhaust operation. This can effectively suppress fluctuations in the pressure field inside the furnace while ensuring efficient exhaust, maintain a high degree of stability in the process environment, and provide reliable environmental protection for the production process.

[0020] 3. This invention adopts an on-demand exhaust mode, triggering the exhaust function only in necessary areas, avoiding long-term, high-flow-rate continuous exhaust, which can significantly save energy consumption; and the entire process is automatically completed by the controller without human intervention, which greatly improves the automation level of the production process, ensures the consistency of process execution, and reduces the risk of errors caused by human operation. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of the synthetic quartz glass deposition furnace in an embodiment of the present invention; Figure 2 This is a cross-sectional view of the installation position of the gas curtain generating device in an embodiment of the present invention; Figure 3 This is a horizontal sectional view of the annular hollow pipe assembly in an embodiment of the present invention; Figure 4 This is a schematic diagram of the control loop of the gas curtain gas supply system in an embodiment of the present invention; Figure 5 This is a horizontal cross-sectional view of a single exhaust region in an embodiment of the present invention; Figure 6 This is a schematic diagram of the sensing and control loop for a single exhaust area in an embodiment of the present invention; Figure 7This is a schematic diagram illustrating the working principle of the gas curtain and exhaust system working together to remove particulate matter in an embodiment of the present invention; Figure 8 This is a logic flowchart of the closed-loop feedback control method for the dynamic environment inside the furnace in an embodiment of the present invention.

[0022] In the diagram: 100-Furnace body; 100a-Inner wall of furnace body; 100b-Outer wall of furnace body; 101-Furnace top; 102-Blowtorch; 103-Rotating lifting crucible; 200-Gas curtain generating device; 201-Annular groove; 210-Annular hollow pipe assembly; 211-Inner pipe; 212-Outer pipe; 213-Inert gas distribution and pressure storage chamber; 214-Gas injection hole; 215-Gas pipeline; 221-Mass flow controller; 222-Linear gas heater; 310a-Upper exhaust zone; 310b-Middle exhaust zone; 310c-Lower exhaust zone; 320-Annular flue; 321-Exhaust port; 330-Exhaust main pipe; 340-Zone electric regulating valve; 410-Particulate matter sensor; 420-Local pressure sensor; 430-Global pressure sensor; 500-Closed-loop feedback controller; 610-Particulate matter cloud. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0024] It should be noted that, depending on the implementation needs, the various steps / components described in this application can be broken down into more steps / components, or two or more steps / components or parts of the operation of steps / components can be combined into new steps / components to achieve the purpose of this invention.

[0025] In this invention, unless otherwise expressly specified and limited, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise expressly and specifically limited.

[0026] Example 1: This example provides a synthetic quartz glass deposition furnace, such as... Figure 1 As shown, it mainly includes: a furnace body 100, a blowtorch 102 installed on the furnace top 101, a rotating and lifting crucible 103 installed in the middle of the furnace cavity, and an integrated dynamic environmental control system.

[0027] The dynamic environmental control system includes: a gas curtain generating device 200 integrated into the furnace top 101; an exhaust system 300 that divides the exhaust zone into an upper exhaust zone 310a, a middle exhaust zone 310b, and a lower exhaust zone 310c, and can be independently controlled in each zone; a sensor array composed of various sensors, including particulate matter sensors 410 and local pressure sensors 420 installed in each exhaust zone, and a global pressure sensor 430 installed in the furnace cavity; and a closed-loop feedback controller 500 for analyzing and processing sensor signals. The controller 500 is electrically connected to the aforementioned devices and all sensors, and through coordinated operation, achieves dynamic and precise removal of pollutants while maintaining a stable furnace environment.

[0028] like Figure 2 As shown, on the lower surface of the furnace top 101 of the deposition furnace, i.e., the side facing the furnace cavity, a ring-shaped groove 201 for positioning and fixing is pre-machined or constructed. The ring-shaped groove 201 is concentrically arranged with the central axis of the furnace top 101. The gas curtain generating device 200 is installed in the ring-shaped groove 201 on the lower surface of the furnace top 101. To ensure that the gas curtain can effectively cover the core deposition area while avoiding interference with the flame of the outermost torch, the radius R of the ring-shaped groove 101 and the radius r of the ring containing the outermost torch 102 preferably satisfy the following relationship: 1.1r < R < 1.4r.

[0029] In this embodiment, the radius d of the ring containing the outermost torch 102 is 800mm, and the radius R of the annular groove 201 is set to 960mm.

[0030] like Figure 3 As shown, the core of the gas curtain generating device 200 is an annular hollow pipe assembly 210, which is installed and fixed in the annular groove. Its main body is a sealed metal pipe with a coaxial double-layer pipe structure. The assembly is preferably made of stainless steel or nickel-based high-temperature alloy material with good heat resistance and high-temperature corrosion resistance.

[0031] In this embodiment, the annular hollow pipe assembly 210 is made of Inconel 601 nickel-based superalloy. The assembly consists of an inner pipe 211 and an outer pipe 212, concentrically integrated. The inner pipe 211 is a hollow annular pipe, forming a completely sealed cooling medium circulation channel inside. This channel has a cooling medium inlet and outlet (not shown), used to connect to an external cooling circulation system (not shown). During operation, the cooling medium is forcibly pumped into this channel and continuously circulates. Through forced convection heat transfer, the heat transferred from the furnace to the entire assembly is efficiently removed, maintaining the temperature of the pipe assembly within the material's tolerance temperature. The cooling medium is preferably nitrogen, compressed air, or water (water is used in this embodiment).

[0032] Furthermore, the outer pipe 212 concentrically covers the inner pipe 211, forming a closed inert gas distribution and storage chamber 213 together with the outer wall of the inner pipe. This storage chamber has at least one inert gas inlet for connecting to an external gas supply system. The inert gas is preferably high-purity nitrogen, argon, or a mixture thereof. Gas injection holes 214 are machined at 20mm intervals along the lower wall of the outer pipe 212. The inert gas is ejected downwards through these holes, forming a cylindrical gas curtain.

[0033] like Figure 4 As shown, to achieve precise control and preheating of the inert gas flow rate, an online gas heater 222 and a mass flow controller (MFC) 221 are connected in series on the gas pipeline 215 connected to the inert gas inlet in the gas supply system. The online gas heater 222 and the mass flow controller 221 operate according to the instructions of the controller 500. The mass flow controller 221 is used to precisely control the flow rate of the inert gas, and its flow rate setting range is 50 to 200 standard liters per minute (SLM). The online gas heater 222 is used to heat the gas to a preset temperature, which is positively correlated with the current furnace temperature to avoid the low-temperature gas flow from impacting the furnace thermal field. The inert gas, after precise flow control and preheating, is sent into the pressure storage chamber. The annular chamber structure makes the gas pressure tend to be uniform across the entire circumference, providing initial conditions for subsequent uniform injection.

[0034] In this embodiment, the preheating temperature of the inert gas is set to 500°C; and the flow rate of the inert gas is precisely controlled by the mass flow controller 221. In this embodiment, the flow rate is set to 100 SLM during steady-state operation.

[0035] like Figure 1 and Figure 5As shown, the sidewall of the furnace body can be divided into 1 to 3 independent annular exhaust zones along its vertical height. The number and layout of these exhaust zones are directly related to the inner diameter of the furnace chamber, to accommodate airflow organization and particulate matter distribution patterns within furnaces of different sizes. The specific configuration is as follows.

[0036] When the furnace inner diameter is less than or equal to 2.0m, the exhaust system is equipped with a central exhaust zone and a lower exhaust zone. The central exhaust zone is located at a height of 100mm to 400mm from the top edge of the crucible in the vertical direction, and is used to capture particles that escape from the crucible and float upwards. The lower exhaust zone is located in an area at a height of 0mm to 300mm from the bottom of the crucible in the vertical direction, and is designed to intercept particles that sink along the furnace wall and enter the recirculated airflow, preventing them from being re-entrained into the upper space inside the furnace.

[0037] When the inner diameter of the furnace is greater than 2.0m, the exhaust system is set with three exhaust zones. In addition to the two exhaust zones mentioned above, an upper exhaust zone is added above the crucible. The position of the upper exhaust zone is set at a height of 400mm to 600mm from the upper edge of the crucible in the vertical direction, which is used to intercept particulate matter at the source.

[0038] In this embodiment, the inner diameter of the furnace is greater than 2.0m, and the exhaust system is set with three exhaust zones, namely the upper exhaust zone 310a, the middle exhaust zone 310b, and the lower exhaust zone 310c.

[0039] Furthermore, to create a uniform and stable negative pressure field within each independent exhaust region, the furnace body 100 employs a hollow double-layer furnace wall structure within the height range of this exhaust region. The inner furnace wall 100a and the outer furnace wall 100b together form an internal annular flue 320. In this embodiment, four exhaust ports 321 penetrating the inner furnace wall 100a are evenly distributed around this annular flue. Gas extracted from the furnace directly enters the annular flue through these exhaust ports. This annular flue serves as a static pressure chamber, its core function being to buffer and homogenize the extracted waste gas, ensuring that the negative pressure at all exhaust port locations tends to be consistent, avoiding localized over-extraction or insufficient suction.

[0040] like Figure 6 As shown in the figure, this diagram illustrates the sensing and control loop for a single exhaust zone. A corresponding zone exhaust main pipe 330 is led out from the outer wall of the annular flue 320, and a particulate matter sensor 410 and a high-precision zone electric regulating valve 340 are sequentially connected in series on this zone exhaust main pipe 330; simultaneously, local pressure sensors 420 are installed within the annular flue 320.

[0041] like Figure 6The electrical connection shown is as follows: both the particulate matter sensor 410 and the local pressure sensor 420 input signals to the closed-loop feedback controller 500. The closed-loop feedback controller 500 then sends precise control commands to the high-precision zone electric regulating valve 340, and based on these commands, continuously adjusts the valve opening within the range of 0% to 100%, thereby dynamically and precisely controlling the total exhaust volume of the entire exhaust zone.

[0042] Furthermore, such as Figure 1 and Figure 6 As shown, a local pressure sensor 420 is installed in each annular exhaust area. Its pressure measuring point passes through the furnace wall through a pressure guide tube, so that the tube opening is flush with the inner wall of the furnace, for accurately measuring the real-time pressure inside the furnace in the corresponding height area. At the same time, the system is also equipped with an independent global pressure sensor 430, which is used to measure the reference total pressure of the furnace cavity. Its measuring point is set in a stable area inside the furnace away from the torch flame and exhaust port. Its reading is used as the pressure reference set value that the control system needs to maintain.

[0043] Furthermore, the particulate sensor 410 is used to monitor the concentration of silica particles in the airflow discharged from a specific area in real time. Specifically, it is installed on the main exhaust pipe 330 of each exhaust area, before the area regulating valve 340. In this example, the particulate sensor 410 is an online high-temperature particulate matter concentration monitor. The controller 500 analyzes and compares the particulate matter concentration readings of each area to determine the specific area where high concentrations of pollutants are generated.

[0044] like Figure 7 As shown, the gas curtain generating device 200, together with the exhaust system 300 of the upper exhaust zone 310a, the middle exhaust zone 310b and the lower exhaust zone 310c, forms a synergistic particulate matter removal method.

[0045] Its working principle is as follows: The downward-sprayed gas curtain acts as a "rigid wall," first isolating the core deposition area from the external furnace cavity; when the controller 500 detects a risk of particle agglomeration in a certain area (taking the central exhaust zone 310b as an example in this case) and activates the exhaust system in that area, the annular flue 320 in that area forms a uniform overall annular negative pressure field; at this time, the downward thrust of the gas curtain and the overall annular suction force formed in the exhaust area work together to guide the constrained particulate cloud 610 to the entire annular exhaust zone and be uniformly sucked into each exhaust port 321 for discharge, greatly avoiding the problem of particulate matter escaping everywhere in the furnace, thereby achieving the overall capture and removal of pollutants at a specific level.

[0046] Example 2, based on the same inventive concept, also provides a dynamic environmental control method for the synthetic quartz glass deposition furnace as described above, such as... Figure 8 As shown, the main decision-making process is as follows.

[0047] Step S1, Particulate Matter Agglomeration Identification and Determination: The closed-loop feedback controller analyzes the signal correlation between the local pressure sensor and the particulate sensor in each exhaust zone to identify whether particulate matter agglomeration that needs to be dealt with has occurred in each exhaust zone. If so, proceed to step S2.

[0048] The conditions for determining the occurrence of particulate matter agglomeration requiring treatment include: Condition 1, the controller detects abnormal pressure fluctuations in a certain exhaust area, that is, the real-time pressure fluctuation amplitude monitored by the local pressure sensor in the current exhaust area exceeds the preset pressure fluctuation threshold (10~40 Pa in this example); Condition 2, the concentration growth rate of silica particles in the exhaust pipe monitored by the particulate matter sensor in the current exhaust area exceeds the preset concentration growth rate threshold (20 (mg / m³) / s in this example, preferably more than 40 (mg / m³) / s).

[0049] When both judgment condition one and judgment condition two are satisfied, it is determined that particulate matter agglomeration requiring treatment has occurred in the current exhaust zone.

[0050] Step S2, coordinated control of exhaust volume in the exhaust system: The closed-loop feedback controller sends a forced exhaust command to the regional electric regulating valve of the exhaust zone where particulate matter agglomerates, increasing the opening of the regional electric regulating valve of that exhaust zone from the initial opening (15%~30% in this example) to the forced exhaust opening (40%~70% in this example) to capture and discharge the agglomerated particulate matter in that exhaust zone; at the same time, based on the feedback signal from the global pressure sensor, the closed-loop feedback controller sends a pressure compensation command to the regional electric regulating valve of the remaining exhaust zone, synchronously reducing the opening of the corresponding regional electric regulating valve by a preset amount to compensate for the pressure loss caused by the forced exhaust, so that the global pressure in the furnace is stabilized within the preset range.

[0051] Step S3, Dynamic control of gas curtain flow: The closed-loop feedback controller sends a dynamic adjustment command to the mass flow controller of the gas curtain generating device according to the current exhaust volume of each exhaust zone, so that the injection flow of inert gas is dynamically changed according to the opening of the regional electric regulating valve of each exhaust zone, so as to maintain the stability of the gas curtain shape.

[0052] The increase in the injection flow rate of the inert gas, ΔL, is proportional to the increase in the opening of the electric regulating valve in the exhaust zone where the particulate matter agglomerates, ΔK.

[0053] In this example, when the opening of the zone control valve is between 40% and 60%, the controller instructs the flow rate of the gas curtain to increase by 15%; when the opening of the zone control valve is between 60% and 70%, the controller instructs the flow rate of the gas curtain to increase by 25%.

[0054] Step S4, system control parameter reset: The closed-loop feedback controller continuously monitors the particulate sensor signal in the exhaust zone where particulate matter agglomerates. When the particulate matter concentration recovers to within 120% of the baseline level before the event and remains stable for 20 seconds, the controller sends a reset command to the mass flow controller of the regional electric regulating valve and the gas curtain generating device in each exhaust zone, so that the system equipment smoothly returns to the initial setting state and prepares for the next adjustment action.

[0055] Example 3: This example provides another configuration of the deposition furnace, which is suitable for deposition furnaces with an inner diameter of less than 2.0m, such as a furnace with an inner diameter of 1.8m.

[0056] The overall structure, gas curtain generating device 200, sensor array, closed-loop feedback controller 500 and its control logic of this embodiment are basically the same as those of Embodiment 1 and Embodiment 2. The main difference is the configuration of the multi-zone exhaust system 300: According to the above scheme, when the inner diameter of the furnace is less than 2.0m, the exhaust system is set in two exhaust zones, that is, it is only divided into a middle exhaust zone 310b and a lower exhaust zone 310c.

[0057] Accordingly, in the control program of the closed-loop feedback controller 500, the global pressure compensation logic is simplified as follows: when a region (e.g., the middle exhaust region 310b) is determined to be an affected region and strong exhaust is performed, the controller 500 instructs another region (i.e., the lower exhaust region 310c) to act as a compensation region and reduce the opening of its region's electric regulating valve. Conversely, when the lower exhaust region 310c is determined to be an affected region, the controller 500 instructs the middle exhaust region 310b to act as a compensation region and reduce its opening to perform compensation.

[0058] Furthermore, all parts of this application that are not described in detail are the same as or implemented using existing technology.

[0059] In summary: 1. This invention organically integrates a gas curtain generating device, a multi-zone exhaust system, a multi-dimensional sensor array, and a closed-loop feedback controller. Through the static pressure chamber design, it ensures the uniformity of suction within each exhaust zone. Relying on the particulate matter concentration monitor on the main exhaust pipe of each zone, it achieves accurate identification of the level of particulate matter agglomeration. At the same time, for the identified particulate matter agglomeration areas, the system performs an overall and uniform capture and removal operation, which can accurately locate and deal with particulate matter agglomeration problems, effectively reduce defects such as bubbles and solid phase inclusions caused by pollutants falling, and improve the product molding quality.

[0060] 2. This invention adopts a closed-loop control logic of collaborative compensation to dynamically regulate the pressure field inside the furnace during the exhaust operation. This can effectively suppress fluctuations in the pressure field inside the furnace while ensuring efficient exhaust, maintain a high degree of stability in the process environment, and provide reliable environmental protection for the production process.

[0061] 3. This invention adopts an on-demand exhaust mode, triggering the exhaust function only in necessary areas, avoiding long-term, high-flow-rate continuous exhaust, which can significantly save energy consumption; and the entire process is automatically completed by the controller without human intervention, which greatly improves the automation level of the production process, ensures the consistency of process execution, and reduces the risk of errors caused by human operation.

[0062] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0063] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0064] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A synthetic quartz glass deposition furnace, comprising a furnace body (100), a blowtorch (102) disposed on the furnace top (101), and a rotating and lifting crucible (103) disposed in the middle of the furnace cavity, characterized in that, The interior of the furnace cavity is divided into multiple exhaust zones along the vertical height direction, and the deposition furnace is also equipped with a dynamic environmental control system. The dynamic environment control system includes: a gas curtain generating device (200) integrated on the furnace top (101), an exhaust system (300) installed on the side wall of the furnace body (100) in each exhaust zone and capable of being controlled separately in each zone, a sensor array for collecting information on the furnace environment, and a closed-loop feedback controller (500) running a dynamic environment control program. The sensor array includes a particulate sensor (410) and a local pressure sensor (420) respectively disposed in each exhaust zone, and a global pressure sensor (430) disposed inside the furnace cavity. The gas curtain generating device (200), the exhaust system (300), the particulate matter sensor (410), the local pressure sensor (420), and the global pressure sensor (430) are all electrically connected to the closed-loop feedback controller (500).

2. The synthetic quartz glass deposition furnace according to claim 1, characterized in that, The furnace top (101) has an annular groove (201) on its lower surface. The annular groove (201) is concentric with the central axis of the furnace top (101). The radius R of the annular groove (201) and the radius r of the ring containing the outermost torch (102) on the furnace top satisfy: 1.1r < R < 1.4r.

3. The synthetic quartz glass deposition furnace according to claim 2, characterized in that, The gas curtain generating device (200) includes an annular hollow pipe assembly (210) fixedly installed in the annular groove (201). The annular hollow pipe assembly (210) consists of an inner pipe (211) and an outer pipe (212). The inner pipe (211) is provided with a cooling medium circulation channel, and the cooling medium inlet and outlet of the cooling medium circulation channel are connected to the cooling circulation system outside the furnace. The outer pipe (212) is coaxially wrapped around the outer ring of the inner pipe (211), and an inert gas distribution and storage cavity (213) is formed between the inner wall of the outer pipe (212) and the outer wall of the inner pipe (211). The lower wall of the outer pipe (212) is provided with a plurality of gas injection holes (214) that are connected to the inert gas distribution and storage cavity (213) at equal intervals along the circumference.

4. The synthetic quartz glass deposition furnace according to claim 3, characterized in that, The inert gas inlet of the inert gas distribution and storage chamber (213) is connected to the gas supply system outside the furnace through a gas pipeline (215). A mass flow controller (221) for controlling the flow rate of inert gas and an online gas heater (222) for heating the inert gas to a preset temperature are connected in series on the gas pipeline (215). Both the mass flow controller (221) and the online gas heater (222) are electrically connected to the closed-loop feedback controller (500).

5. A synthetic quartz glass deposition furnace according to claim 1, characterized in that, The number of exhaust zones is positively correlated with the inner diameter of the furnace cavity; the furnace sidewall of each exhaust zone is composed of an inner furnace wall (100a) and an outer furnace wall (100b), and an annular flue (320) is formed between the inner furnace wall (100a) and the outer furnace wall (100b), and the inner furnace wall (100a) is uniformly provided with multiple exhaust ports (321) that are connected to the annular flue (320) in the circumferential direction.

6. A synthetic quartz glass deposition furnace according to claim 5, characterized in that, The annular flue (320) is connected to the regional exhaust pipe (330) extending from the outer wall (100b) of the furnace body. The regional exhaust pipe (330) is equipped with a particulate sensor (410) for real-time monitoring of silica particulate matter concentration in the airflow and a regional electric regulating valve (340) for controlling the exhaust volume of the area. Both the particulate sensor (410) and the regional electric regulating valve (340) are electrically connected to the closed-loop feedback controller (500).

7. A synthetic quartz glass deposition furnace according to claim 5, characterized in that, The local pressure sensor (420) is used to measure the real-time pressure inside the furnace in the corresponding exhaust zone. Its pressure measuring point is inserted into the side wall of the furnace body through a pressure guide pipe, and the opening of the pressure guide pipe is flush with the inner wall (100a) of the furnace body. The global pressure sensor (430) is used to measure the reference total pressure inside the furnace cavity. Its pressure measuring point is located on the lower surface of the furnace top (101) away from the blowtorch (102).

8. A dynamic environmental control method for a synthetic quartz glass deposition furnace as described in any one of claims 1 to 7, characterized in that, Includes the following steps: S1, Particulate matter agglomeration identification and determination: The closed-loop feedback controller analyzes the signal correlation between the local pressure sensor and the particulate matter sensor in each exhaust zone to identify whether particulate matter agglomeration that needs to be dealt with has occurred in each exhaust zone. If so, proceed to step S2. S2, Exhaust system exhaust volume coordinated control: The closed-loop feedback controller sends a forced exhaust command to the regional electric regulating valve of the exhaust zone where particulate matter agglomerates, increasing the opening of the regional electric regulating valve of that exhaust zone from the initial degree to the forced exhaust opening, so as to capture and discharge the agglomerated particulate matter in that exhaust zone; at the same time, based on the feedback signal of the global pressure sensor, the closed-loop feedback controller sends a pressure compensation command to the regional electric regulating valve of the remaining exhaust zones, synchronously reducing the opening of the corresponding regional electric regulating valve by a preset amount, so as to stabilize the global pressure in the furnace within a preset range; S3, Dynamic control of gas curtain flow: The closed-loop feedback controller sends a dynamic adjustment command to the mass flow controller of the gas curtain generating device according to the current exhaust volume of each exhaust zone, so that the injection flow of inert gas is dynamically changed according to the opening of the regional electric regulating valve of each exhaust zone to maintain the stability of the gas curtain shape. S4, System control parameter reset: The closed-loop feedback controller continuously monitors the particulate sensor signal in the exhaust zone where particulate matter agglomerates. When the particulate matter concentration returns to the baseline concentration range and is maintained for a preset time period, a reset command is sent to the mass flow controller of the regional electric regulating valve and the gas curtain generating device in each exhaust zone.

9. The dynamic environment control method according to claim 8, characterized in that... In step S1, the criteria for determining the occurrence of particulate matter agglomeration requiring treatment include: 1) Judgment condition one: The real-time pressure fluctuation amplitude detected by the local pressure sensor in the current exhaust zone exceeds the preset pressure fluctuation threshold. 2) Judgment condition two: The growth rate of silica particulate matter concentration in the exhaust pipe detected by the particulate matter sensor in the current exhaust zone exceeds the preset concentration growth rate threshold. When both judgment condition one and judgment condition two are satisfied, it is determined that particulate matter agglomeration requiring treatment has occurred in the current exhaust zone.

10. The dynamic environment control method according to claim 8, characterized in that... In step S3, the increase in the injection flow rate of the inert gas, ΔL, is proportional to the increase in the opening of the electric regulating valve in the exhaust zone where the particulate matter agglomerates, ΔK.

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