Air pre-treatment system for gas phase white carbon black production and gas phase white carbon black production system

Abstract

The application provides an air pretreatment system and a fumed white carbon black production system, which comprises a sealed shell, a rotating runner arranged in the sealed shell, a honeycomb structure in the runner, a wall surface of the runner loaded or filled with an adsorbent, a sealing assembly fixed to the inner part of the sealed shell and attached to the end surface of the runner, an adsorption area and a regeneration area separated from each other in the inner cavity of the sealed shell, a desorption area, a deep regeneration area and a cooling area sequentially separated by a partition plate along the rotating direction of the runner in the regeneration area, a communication between the deep regeneration area and the desorption area through an internal air duct arranged in the sealed shell, a communication of the air inlet end of the deep regeneration area to a reactant material pipeline heat exchanger of the fumed white carbon black production system, and an independent communication of the cooling area to ambient air. Through the above scheme, the tail gas discharged from the deep regeneration area is introduced into the desorption area as a crude desorption heat source through the internal air duct arranged in the back air duct layer of the sealed shell on the same side of the runner, the sensible heat and latent heat are all reserved, external pipelines and condensation and dehumidification equipment are not needed, the system structure is greatly simplified, and the heat energy recovery efficiency is high.

Description

Technical Field

[0001] This application relates to the field of fumed silica production technology, and more particularly to an air pretreatment system and a fumed silica production system for fumed silica production. Background Technology

[0002] Fumed silica is typically produced by the high-temperature hydrolysis of silicon halides in an oxyhydrogen flame. This process has extremely high requirements for the humidity of the reaction air; even trace amounts of moisture can severely affect the particle size and dispersion properties of the fumed silica. The dew point temperature of the reaction air usually needs to be controlled below -40°C to ensure that the core performance indicators of the final product, such as specific surface area and tap density, meet industrial standards.

[0003] Currently, the industry commonly uses general-purpose adsorption dryers for air pretreatment. These adsorption dryers typically employ a dual-tower or multi-tower switching process, removing moisture from the air by filling it with adsorbents such as silica gel or molecular sieves. In actual production, a high-power air compressor is required to provide high-pressure gas to overcome the resistance of the adsorption bed. Furthermore, the dehydration and regeneration of the adsorbent relies entirely on a high-power electric heater to heat the air before it is passed into the adsorption bed for sweeping and regeneration. The electric heater power of a single unit is typically 30kW-100kW, consuming tens to hundreds of kilowatt-hours of electricity per hour, resulting in extremely high energy consumption and production costs.

[0004] In recent years, rotary dehumidification systems have been widely used in HVAC and general industrial dehumidification fields due to their advantages such as continuous operation and small footprint. However, directly applying conventional rotary dehumidification systems to the continuous production of fumed silica presents several insurmountable technical drawbacks, specifically: First, it cannot be directly integrated with the special heat source of the precipitated silica system, resulting in a significant energy consumption problem. Conventional rotary dehumidifier systems typically have independent electric or gas heating modules for regeneration. If used directly for the energy-intensive production of precipitated silica, it would substantially increase the overall operating cost. Even if industrial waste heat generated in the precipitated silica production process (such as heat exchange of reactants) is introduced, the high-temperature hot air is directly discharged after a single desorption cycle through the conventional rotary dehumidifier, resulting in extremely low heat utilization and making it impossible to meet the high-volume, high-depth dehumidification requirements of the precipitated silica process.

[0005] Secondly, the deep regeneration and cooling processes involve thermodynamic interference, affecting the dehumidification limit. The fumed silica process has extremely stringent requirements for air dew point. Conventional rotary systems often only have simple "adsorption zones" and "regeneration zones." If industrial waste heat is used to forcibly perform high-temperature deep desorption, the adsorbent at high temperatures will lose its adsorption activity when it enters the adsorption zone, failing to effectively adsorb moisture from the air. This will lead to excessive moisture content in the outlet air. If this humid air enters the downstream fumed silica reactor, it will cause catastrophic equipment corrosion and product spoilage. Summary of the Invention

[0006] This application provides an air pretreatment system and a fumed silica production system for fumed silica production, aiming to solve the problems of heat source waste and low dehumidification efficiency caused by the incompatibility of traditional rotary dehumidification systems with fumed silica production systems.

[0007] To address the aforementioned issues, an air pretreatment system for fumed silica production includes: a sealed housing; a rotating impeller housed within the sealed housing; a sealing assembly fitted to the end face of the impeller; the sealing assembly divides the end face of the impeller and the inner cavity of the sealed housing into independent adsorption and regeneration zones; the regeneration zone is sequentially divided into a desorption zone, a deep regeneration zone, and a cooling zone by partitions along the rotation direction of the impeller; the exhaust outlet of the deep regeneration zone and the air inlet of the desorption zone are located on the same side of the impeller, and the two are connected through an internal air duct housed within the sealed housing; the air inlet of the deep regeneration zone is connected to the heat exchanger of the reaction material pipeline of the fumed silica production system; and the cooling zone is independently connected to the external ambient air.

[0008] With the above scheme, the exhaust gas discharged from the deep regeneration zone is not discharged from the system, but is directly introduced into the desorption zone as a coarse desorption heat source through the internal air duct of the back air duct layer in the sealed shell, on the same side of the rotor. The sensible heat and latent heat are all retained, and there is no need for external pipelines and condensation dehumidification equipment. The system structure is greatly simplified and the heat recovery efficiency is high.

[0009] Furthermore, the internal space of the regeneration zone corresponding to the sealed housing is divided into an end face sealing layer near the rotor and a back air duct layer away from the rotor along the axial direction; a partition is provided on the end face sealing layer and abuts against the rotor; the internal air duct is enclosed in the back air duct layer and is connected to the desorption zone and the deep regeneration zone respectively through the interface that penetrates the end face sealing layer.

[0010] Furthermore, the internal air duct is formed by an arc-shaped air guide baffle and an end face sealing layer; the interface includes two openings that penetrate the end face sealing layer, which are respectively connected to the exhaust outlet of the deep regeneration zone and the air inlet of the desorption zone.

[0011] Furthermore, the sealing assembly is made of polytetrafluoroethylene and includes an outer peripheral sealing ring and several radial sealing strips; the several radial sealing strips are arranged radially to correspondingly separate the adsorption zone and the regeneration zone, and maintain an elastic contact with the end face of the rotor with a compression amount of 1mm-3mm.

[0012] Furthermore, the ratio of the rotor end face area of ​​the adsorption zone to that of the regeneration zone is 2:1; within the regeneration zone, the ratio of the rotor end face area of ​​the desorption zone to that of the deep regeneration zone is 1:1.

[0013] Furthermore, the air inlet of the adsorption zone is connected to an air filter, and a process air supply fan is installed on the process air duct connected to the adsorption zone; the air outlet of the desorption zone is connected to a dehumidification duct.

[0014] Furthermore, a temperature regulating device is installed on the high-temperature regeneration air duct leading into the deep regeneration zone. The temperature regulating device includes a water-cooled temperature control mechanism installed on the upstream duct of the heat exchanger and an venting regulating valve installed on the high-temperature regeneration air duct.

[0015] The present invention also provides a fumed silica production system, comprising a reactor, an aggregator, a cyclone separator and a deacidifier connected in sequence, and the aforementioned air pretreatment system; a heat exchanger is connected in series on the material conveying pipeline between the reactor and the aggregator; the process air outlet of the air pretreatment system is connected to the reactor.

[0016] With the above scheme, the heat exchanger is directly connected in series on the material pipeline between the reactor and the aggregator, using the waste heat of the high-temperature material at the reactor outlet as the heat source for the regeneration zone. There is no need to configure additional electric heating or gas equipment, resulting in low operating costs. At the same time, the waste heat resources of the air pretreatment system and the production system form a closed loop for utilization, and the overall energy efficiency is significantly higher than that of an independently operating pretreatment system.

[0017] The present invention also provides a control method for the above-mentioned air pretreatment system, comprising the following steps: The treated air enters the adsorption zone, is dehumidified by the adsorbent, and is then output as pretreated air. The adsorbent undergoes desorption, deep regeneration, and cooling in sequence; In the desorption zone, the exhaust gas from the deep regeneration zone is heated and desorbed by the internal air duct. Deep regeneration is carried out in the deep regeneration zone by heating with a high-temperature heat source from the heat exchanger of the reactant pipeline of the fumed silica production system for deep desorption. Cooling is achieved by introducing ambient temperature air into the cooling zone; When the regeneration air temperature is below 100℃, the adsorbent decelerates with the impeller to increase the residence time based on the deviation between the air temperature and the median of the optimal temperature range, and the frequency of the process air supply fan is reduced simultaneously.

[0018] Through the above scheme, high-temperature dry air first enters the deep regeneration zone to thoroughly remove stubborn moisture from micropores, and the discharged medium-temperature humid exhaust gas is introduced into the desorption zone to remove free water. High-temperature removal of stubborn moisture and medium-temperature removal of free water are reasonably matched and the overall regeneration efficiency is high. When the regeneration air temperature is below 100℃, the rotor speed is reduced to increase the adsorbent residence time, and the frequency of the process fan is reduced to decrease the processing air volume. The dual setting of extending the time and reducing the load is used to deal with insufficient waste heat and ensure that the outlet dew point meets the standard.

[0019] Furthermore, the temperature of the high-temperature regeneration air introduced into the deep regeneration zone is 100℃-140℃, and the temperature of the humid and hot exhaust gas discharged from the desorption zone is 80℃-100℃. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the air pretreatment system provided in an embodiment of this application; Figure 2 This is a schematic diagram of the rotary wheel structure provided in an embodiment of this application; Figure 3 This is a schematic diagram of a fumed silica production system provided in an embodiment of this application; Explanation of reference numerals in the attached figures: 1. Sealed housing; 2. Rotary wheel; 4. Sealing assembly; 41. Radial sealing strip; 42. Outer peripheral sealing ring; 5. Adsorption zone; 6. Regeneration zone; 6a. Desorption zone; 6b. Deep regeneration zone; 6c. Cooling zone; 6e. Internal air duct; 6f. Baffle plate; 7. Air filter; 8. Process air supply fan; 9. High-temperature regeneration air duct; 10. Heat exchanger; 11. Temperature control device; 111. Water-cooled temperature control mechanism; 112. Vent regulating valve; 12. Exhaust duct; 14. Cooling fan; 15. Cooling air filter; 100. Reactor; 200. Aggregator; 300. Cyclone separator; 400. Deacidifier. Detailed Implementation

[0021] The following will be combined with the appendix Figures 1-3 The embodiments of the technical solution of this application are described in detail below. The following embodiments are only used to illustrate the technical solution of this application more clearly, and are therefore only examples and should not be used to limit the scope of protection of this application.

[0022] like Figure 1 and Figure 2 As shown, the air pretreatment system for fumed silica production provided by the present invention mainly includes a sealed housing 1; a rotating wheel 2 rotatably disposed within the sealed housing 1; a drive mechanism rotatably connected to the rotating wheel 2; and a sealing assembly 4 attached to the end face of the rotating wheel 2. The sealing assembly 4 divides the end face of the rotating wheel 2 and the inner cavity of the sealed housing 1 into an independent adsorption zone 5 and a regeneration zone 6. The regeneration zone 6 is sequentially divided into a desorption zone 6a, a deep regeneration zone 6b, and a cooling zone 6c by a partition 6f along the rotation direction of the rotating wheel 2. The exhaust outlet of the deep regeneration zone 6b and the air inlet of the desorption zone 6a are located on the same side of the rotating wheel 2, and the two are connected through an internal air duct 6e disposed within the sealed housing 1. The air inlet of the deep regeneration zone 6b is connected to the heat exchanger 10 of the reaction material pipeline of the fumed silica production system. The cooling zone 6c is independently connected to the external ambient air.

[0023] This application utilizes a rotor 2 structure containing adsorbent for air pretreatment and introduces waste heat from the combustion process during fumed silica production to regenerate the adsorbent. The exhaust gas from the deep regeneration zone 6b is directly introduced into the desorption zone 6a on the same side of the rotor 2 via an internal air duct 6e located within the sealed housing 1, serving as a coarse desorption heat source. Compared to existing technologies that draw heat through external pipelines, condense and dehumidify it, and then reheat it for return, this invention retains all sensible and latent heat for coarse desorption, significantly improving heat recovery efficiency. It also eliminates the need for external pipelines, condensers, dehumidification devices, and other equipment, greatly simplifying the system structure and reducing space requirements. Furthermore, this solution avoids connecting high-energy-consuming external heating equipment. By connecting to the reaction material pipeline heat exchanger 10 of the fumed silica production system, the waste heat from the high-temperature material at the reactor outlet after heat exchange is utilized, achieving the recycling of internal heat energy and air. This objectively reduces the overall power and thermal energy consumption of the process, effectively saving production costs.

[0024] Specifically, the sealing housing 1 is a cylindrical structure made of welded stainless steel, which has good sealing performance and corrosion resistance. End caps are provided at both ends of the sealing housing 1, and the end caps have inlet and outlet ports corresponding to the adsorption zone 5 and the regeneration zone 6, respectively.

[0025] The rotating wheel 2 is rotatably disposed inside the sealed housing 1. The rotating wheel 2 has a disc-shaped structure, its diameter matching the inner diameter of the sealed housing 1, and its axial thickness is 200mm-500mm. The interior of the rotating wheel 2 has a honeycomb structure, with honeycomb channels extending axially along the rotating wheel 2, allowing gas to pass freely along the axial direction. The walls of the honeycomb channels serve as adsorption carriers, on which adsorbents are loaded or filled. The adsorbent is at least one of silica gel, activated alumina, or molecular sieves. In this embodiment, silica gel is preferred because it has a large specific surface area and suitable pore size distribution, exhibiting good adsorption selectivity for water molecules in the air. The honeycomb structure results in a large flow area and short flow channels when air passes through, leading to low system resistance, far lower than the resistance level of traditional fixed-bed adsorbers.

[0026] The drive mechanism is rotatably connected to the rotating wheel 2 and is used to drive the rotating wheel 2 to rotate slowly within the sealed housing 1. The specific form of the drive mechanism can be selected according to the actual scenario; in this embodiment, it preferably includes a motor, a gearbox, and a transmission belt. The motor is fixedly mounted on the outer wall of the sealed housing 1. The output shaft of the motor is connected to the input end of the gearbox. The output end of the gearbox drives the driven pulley connected to the central shaft of the rotating wheel 2 through the driving pulley and the transmission belt, thereby driving the rotating wheel 2 to rotate. After being decelerated by the gearbox, the motor drives the rotating wheel 2 to rotate slowly at a speed of 0.05 r / min to 0.17 r / min. The rotation speed of the rotating wheel 2 can be flexibly adjusted according to the production load and air humidity, and is usually controlled at 3 to 10 revolutions per hour, that is, a complete rotation cycle is completed every 6 to 20 minutes.

[0027] The central shaft of the rotor 2 is mounted on the sealed housing 1 via a rotor support assembly. The rotor support assembly includes bearing seats and support bearings located on both sides of the housing, providing radial and axial load-bearing support for the rotor. A shaft end dynamic seal assembly is installed at the point where the central shaft exits the sealed housing 1. This assembly employs a combination of labyrinth seal and lip seal to ensure the airtightness of the housing during shaft rotation, preventing air exchange between the inside and outside of the housing and affecting the dehumidification effect. An axial thrust structure is also provided on the central shaft, which, in conjunction with the limiting end face of the bearing seat, restricts the axial movement of the rotor, ensuring a stable gap between the two end faces of the rotor and the sealing assembly 4, maintaining consistent sealing compression, and preventing seal failure or sudden changes in operating resistance due to axial movement.

[0028] Furthermore, the sealing assembly 4 is fixed inside the sealing housing 1 and fits against the end face of the rotating wheel 2. Specifically, as shown... Figure 2 As shown, the sealing assembly 4 includes a radial sealing strip 41 and an outer peripheral sealing ring 42. The radial sealing strip 41 is arranged in a fan shape with an included angle of 120° on both end faces of the rotor 2, extending from the center of the rotor 2 to the edge, dividing the end face of the rotor into two independent areas: an adsorption zone 5 and a regeneration zone 6. The outer peripheral sealing ring 42 is arranged along the outer periphery of the rotor 2 to seal the annular gap between the rotor 2 and the sealing housing 1, preventing airflow from bypassing the outer edge of the rotor 2. The sealing assembly 4 is made of polytetrafluoroethylene, which has excellent heat resistance and a low coefficient of friction. The sealing assembly 4 maintains an elastic contact with the end face of the rotor 2 with a compression amount of 1mm-3mm, which can effectively prevent airflow between the adsorption zone 5 and the regeneration zone 6, and will not affect the normal rotation of the rotor 2 due to excessive frictional resistance. At the same time, this compression range can maintain stable sealing performance during long-term operation.

[0029] Continue to refer to the appendix Figure 2 The ratio of the rotor end face area of ​​adsorption zone 5 to regeneration zone 6 is 2:1, that is, adsorption zone 5 occupies 2 / 3 of the total rotor end face area, which is a 240° fan-shaped area, and regeneration zone 6 occupies 1 / 3 of the total rotor end face area, which is a 120° fan-shaped area. This ratio is the optimal partitioning scheme determined after extensive experimental verification: outside air enters adsorption zone 5, where the moisture is adsorbed by the adsorbent. The dried air is then output from the outlet of adsorption zone 5 and sent to the reactor of the fumed silica production system. Two-thirds of the area ensures sufficient processing gas volume and adequate residence time, so that the outlet dew point meets the process requirements and the outlet temperature reaches 50°C, providing the basic temperature for the combustion of the reaction gas required by the reactor. Regeneration zone 6 is used to desorb and regenerate the adsorbent that has adsorbed moisture, restoring its adsorption performance. It uses one-third of the area. During the continuous rotation of rotor 2, the adsorbent that has completed moisture absorption enters regeneration zone 6 in sequence. After being desorbed and regenerated by high-temperature regeneration air, it is transferred back to adsorption zone 5 for operation, achieving continuous and uninterrupted air drying treatment.

[0030] Along the rotation direction of the rotor 2, the regeneration zone 6 is sequentially divided into three independent sub-regions by the partition 6f: a desorption zone 6a, a deep regeneration zone 6b, and a cooling zone 6c. Within the regeneration zone 6, the ratio of the rotor end-face area of ​​the desorption zone 6a to that of the deep regeneration zone 6b is 1:1; the desorption zone 6a and the deep regeneration zone 6b together occupy the majority of the total area of ​​the regeneration zone, with the remaining area being the cooling zone 6c. The equal area of ​​the desorption zone 6a and the deep regeneration zone 6b ensures a balanced residence time for coarse desorption and deep regeneration, while the cooling zone 6c is configured with an appropriate area to meet the adsorbent cooling requirements. In a preferred embodiment, the ratio of the rotor end-face area of ​​the desorption zone 6a, the deep regeneration zone 6b, and the cooling zone 6c is 2:2:1. As the rotor 2 rotates, the moisture-loaded adsorbent sequentially transfers from the adsorption zone 5 into the desorption zone 6a, the deep regeneration zone 6b, and the cooling zone 6c, and then returns to the adsorption zone 5, completing a full adsorption-regeneration cycle.

[0031] The exhaust outlet of the deep regeneration zone 6b and the air inlet of the desorption zone 6a are located on the same side of the rotor 2. They are connected by an internal air duct 6e located within the sealed housing 1, enabling the cascade utilization of waste heat from the regeneration exhaust gas. Specifically, the sealed housing 1, corresponding to the internal space of the regeneration zone 6, is divided into two layers along the axial direction of the rotor 2: an end-face sealing layer near the end face of the rotor 2, and a back air duct layer away from the rotor 2. A partition 6f is fixedly installed within the end-face sealing layer, and a sealing component 4 is embedded in its end face facing the rotor 2, abutting against the end face of the rotor 2 to achieve airtight separation between the sub-regions. The internal air duct 6e is enclosed within the back air duct layer, not intruding into the rotation space of the rotor 2, thus avoiding interference with the rotor.

[0032] like Figure 2 As shown, the internal air duct 6e is formed by an arc-shaped air guide baffle and the back wall of the end-face sealing layer; the arc of the arc-shaped air guide baffle corresponds to the fan-shaped angle between the exhaust outlet of the deep regeneration zone 6b and the air inlet of the desorption zone 6a. The two ends of the internal air duct 6e are connected through two interfaces that penetrate the end-face sealing layer: the first opening corresponds to the exhaust outlet of the deep regeneration zone 6b, and the second opening corresponds to the air inlet of the desorption zone 6a.

[0033] This results in the following tiered airflow path: the medium-temperature exhaust gas discharged from the deep regeneration zone 6b enters the internal air duct 6e within the back air duct layer from the dehumidification outlet, flows along the arc-shaped air guide baffle, and is sent into the air inlet of the desorption zone 6a through the second opening, serving as a preheating heat source for coarse desorption. After the coarse desorption pretreatment, most of the free water in the adsorbent has been removed and discharged with the airflow from the desorption zone. The adsorbent entering the deep regeneration zone 6b retains only a small amount of bound water inside the micropores; the high-temperature regeneration air only removes a small amount of moisture, therefore the exhaust gas discharged from the deep regeneration zone is not saturated with water vapor. This unsaturated medium-temperature exhaust gas mainly carries sensible heat, which is introduced into the desorption zone 6a to raise the temperature of the adsorbent matrix, preventing water vapor condensation. The entire heat exchange and flow guiding process is completed inside the sealed shell 1, and the sensible heat of the exhaust gas is fully recovered and utilized without any additional overflow loss.

[0034] During operation, the initial temperature of the adsorbent entering the desorption zone 6a is 40-60℃. The medium-temperature exhaust gas first rapidly raises the overall temperature of the adsorbent through convection heat transfer. Once the adsorbent temperature rises above the exhaust gas dew point, the free water on the adsorbent surface begins to vaporize and desorb, exiting from the outlet of the desorption zone 6a along with the exhaust gas. This process utilizes the sensible heat of the exhaust gas to preheat and coarsely desorb the adsorbent, while a large amount of free water is directly discharged from the desorption zone, significantly reducing the heat load and desorption load of deep regeneration and improving overall energy efficiency.

[0035] Cooling zone 6c is equipped with an independent cooling ventilation circuit. The air inlet of cooling zone 6c is connected in sequence to cooling fan 14 and cooling air filter 15. Cooling fan 14 draws ambient air at room temperature and sends it into cooling zone 6c through cooling air filter 15. When the ambient air passes through the honeycomb channel of the rotor, it exchanges heat with the high-temperature adsorbent that has completed deep regeneration, reducing the adsorbent temperature to the suitable adsorption temperature range of 40-60℃. The cooled adsorbent returns to adsorption zone 5 with the rotation of rotor 2, starting a new adsorption cycle.

[0036] In another preferred embodiment, the air inlet of cooling zone 6c is connected to the air inlet pipe at the front end of adsorption zone 5 via a branch pipe. Purified air is drawn from upstream of process fan 8 as the cooling air source. A cooling branch regulating valve and a cooling fan 14 are installed on the branch pipe. This air source is pre-filtered and dust-removed by air filter 7, which eliminates the need for a separately installed cooling air filter 15 and prevents dust from entering the impeller. At the same time, the humidity of the cooling air is relatively stable, reducing the risk of the adsorbent reabsorbing moisture during the cooling process.

[0037] The heated air after cooling and heat exchange is directly discharged to the outside environment from the air outlet of cooling zone 6c, or it can be connected to the waste heat recovery pipeline network according to the needs of the plant area.

[0038] Combination Figure 1As shown, in the process air circuit, a process air supply fan 8 is installed on the process air duct connected to the adsorption zone 5 to overcome the mechanical resistance when the gas flows through the adsorbent layer filled in the impeller 2. In the specific implementation process, the process air supply fan 8 has two equivalent configuration methods according to the flow field design requirements. The first implementation method is: the process air supply fan 8 is installed as a blower at the air inlet of the adsorption zone 5. In this structure, the ambient temperature air to be treated first enters the process air supply fan 8, and after being pressurized, it is pushed into the interior of the adsorption zone 5 under positive pressure, forcibly passing through the impeller 2 for dehumidification. The dehumidified dry air is then discharged from the air outlet of the adsorption zone 5 and sent to the reactor. The second implementation method is as follows: the process air supply fan 8 is set as an induced draft fan at the outlet end of the adsorption zone 5. In this structure, the ambient temperature air to be treated is drawn in from the inlet end under the negative pressure of the pipeline and passes through the adsorption zone 5 of the rotor 2. After being adsorbed and dried, the process air flows out of the adsorption zone 5 and enters the inlet of the process air supply fan 8. Then, it is sent out from the outlet end of the process air supply fan 8 with a slight positive pressure and directed to the reactor. Thanks to the rotor structure adopted in this application, which has thin-layer or honeycomb macroscopic flow characteristics, this application preferably uses a blower. Dry air can be obtained by directly passing the filtered atmosphere through the adsorption zone 5, which meets the requirements for continuous and stable delivery of dry air for the fumed silica production line. This objectively limits the power of the power shaft required for system operation and realizes low-energy delivery.

[0039] The air inlet of regeneration zone 6 is connected to the reaction material pipeline heat exchanger 10 of the fumed silica production system via high-temperature regeneration air duct 9. The reaction material pipeline heat exchanger 10 utilizes the waste heat released by the high-temperature material generated by the reactor 100 on the subsequent material conveying pipeline to heat the ambient air to 100℃-140℃, which is then used as high-temperature regeneration air and introduced into regeneration zone 6 via high-temperature regeneration air duct 9 to desorb and regenerate the moisture-saturated adsorbent.

[0040] Furthermore, the regeneration zone 6 is equipped with a dehumidification pipe 12, which is connected to the air outlets of the desorption zone 6a and the cooling zone 6c via branch pipes. Moisture desorbed from the adsorbent is swept away by the regeneration airflow and discharged to the outside of the system via the dehumidification pipe 12. Specifically, the dehumidification pipe 12 has two optional implementations: first, a dehumidification fan is installed on the dehumidification pipe 12; second, the dehumidification pipe 12 only has an open dehumidification outlet, without additional ventilation equipment.

[0041] When the exhaust pipe 12 is only equipped with an open exhaust port and no exhaust fan is configured, the entire regeneration air circuit relies on the high-temperature regeneration air sent by the heat exchanger 10 to maintain a positive pressure of 4kPa to 6kPa. The pressure difference formed by this positive pressure and the external atmospheric pressure is used to drive the airflow autonomously, so that the hot air flows through the high-temperature regeneration air pipe 9, the deep regeneration zone 6b, the internal air duct 6e, and the desorption zone 6a in sequence, and finally depressurizes and is discharged from the exhaust port, without the need for an additional negative pressure suction device.

[0042] An auxiliary air supply fan can be added to the pipeline supplying ambient temperature regeneration fresh air to heat exchanger 10. The auxiliary air supply fan pre-pressurizes the ambient temperature fresh air to 4kPa~6kPa before sending it into heat exchanger 10. The fresh air absorbs the waste heat of the high-temperature material inside the heat exchanger and rises in temperature. A pressure compensation device can be installed on the pipeline after heat exchange to ensure a continuous and stable output of regeneration hot air at a pressure of 4kPa~6kPa at the heat exchanger outlet, providing sufficient air pressure for purging the regeneration zone, forming a stable airflow in the regeneration loop, and realizing effective regeneration and drying of the rotary adsorbent.

[0043] Furthermore, the temperature regulating device 11 is connected to the heat exchanger 10 and the high-temperature regeneration air duct 9 respectively, for regulating the regeneration air temperature. Specifically, the temperature regulating device 11 includes a vent regulating valve 112 and a temperature sensor installed on the high-temperature regeneration air duct 9. The vent regulating valve 112 can be an electric butterfly valve or an electric gate valve, installed on the bypass pipe or at the end of the high-temperature regeneration air duct 9. When the regeneration air temperature output by the heat exchanger 10 is too high, the control system automatically opens the vent regulating valve 112 to directly vent some of the high-temperature hot air, increasing the air velocity in the duct and reducing the air temperature that finally reaches the regeneration zone 6; conversely, when the air temperature is too low, the vent regulating valve 112 is closed or shut off to achieve rapid fine-tuning of the regeneration air temperature.

[0044] Furthermore, the temperature control device 11 also includes a water-cooled temperature control mechanism 111 installed on the upstream pipeline of the reactant pipeline heat exchanger 10. The water-cooled temperature control mechanism 111 controls the flow rate of cooling water to pre-cool the reactants entering the heat exchanger 10, adjusting the upper limit of the heat exchange temperature of the heat exchanger 10, thereby coarsely adjusting the regeneration air temperature over a wide range. When the temperature of the reactants rises abnormally, the flow rate of cooling water in the water-cooled temperature control mechanism 111 is increased, allowing the materials to be pre-cooled before entering the heat exchanger 10, thus significantly reducing the regeneration air temperature.

[0045] Through the temperature control adjustment of the water-cooled temperature control mechanism 111 (pre-coarse adjustment) and the hot air venting fine adjustment of the venting regulating valve 112, the present invention can control the temperature of the high-temperature regeneration air entering the regeneration zone 6 within the optimal range of 100℃-140℃, and the high-temperature regeneration air pressure output from the heat exchanger 10 to the high-temperature regeneration air pipeline 9 is 4kPa-6kPa, ensuring that the desorption and regeneration effect of the adsorbent is stable and reliable.

[0046] On the other hand, such as Figure 3 As shown, the present invention also provides a fumed silica production system, including a reactor 100, an aggregator 200, a cyclone separator 300 and a deacidifier 400 connected in sequence by pipelines, and also includes the aforementioned air pretreatment system.

[0047] Reactor 100 is the reaction equipment of this system. Silicon halides, such as silicon tetrachloride, undergo hydrolysis with hydrogen and air in a high-temperature flame within reactor 100, producing fumed silica particles and hydrogen chloride as byproducts. The air required for the reaction is supplied by the process air supply fan 8 through the process air outlet of the air pretreatment system. Due to the adsorption drying process of the rotor 2, the air entering reactor 100 experiences a certain temperature rise due to the heat transfer effect of the rotor 2, directly saving preheating energy consumption of the reactor.

[0048] The outlet of reactor 100 is sequentially connected to collector 200 and cyclone separator 300. The high-temperature silica particles and mixed gas generated in the reaction first enter collector 200 for preliminary gas-solid separation and product collection, and then enter cyclone separator 300 for further separation and recovery of fine particles, improving product yield. Downstream of cyclone separator 300 is deacidifier 400. Deacidifier 400 deacidifies the separated and collected silica, removing residual hydrogen chloride to ensure the product meets high acidity standards such as food-grade or pharmaceutical-grade. The exhaust gas from deacidifier 400 is treated to meet emission standards.

[0049] Heat exchangers 10 are connected in series on the material conveying pipeline between the reactor 100 and the collector 200. Since the material temperature immediately leaving the reactor 100 reaches 300℃-600℃, the material conveying pipeline is a high-temperature heat source channel. In the specific equipment selection of heat exchangers 10, considering the extremely harsh operating conditions in the production of fumed silica, including high temperature, extremely fine fumed silica solid particles, and the presence of highly corrosive hydrogen chloride gas, the heat exchanger 10 for the reaction material pipeline is preferably a straight-tube shell-and-tube heat exchanger. The tube side carries the high-temperature reaction material containing fumed silica particles and hydrogen chloride, and a larger straight tube diameter is used to prevent dust blockage and ash accumulation; the shell side carries clean, room-temperature air. To meet the requirements of high temperature resistance and acid corrosion resistance, the pressure-bearing material of the heat exchanger 10 in contact with the high-temperature corrosive material is preferably Hastelloy or silicon carbide composite material to ensure structural stability and high heat transfer efficiency under long-term extreme operating conditions.

[0050] The water-cooled temperature control mechanism 111 is located upstream of the pipeline, providing pre-cooling regulation for high-temperature materials. The heat exchanger 10, located downstream of the pipeline, uses the material transport pipeline as the heat source. Through air-to-air heat exchange, it heats ambient air to 100℃-140℃ and outputs it as regeneration air, which is then supplied to the regeneration zone 6 of the air pretreatment system via the high-temperature regeneration air pipeline 9. During the aforementioned heat exchange process, the ambient air supplied to the shell side (or the side to be heated) of the heat exchanger 10 is drawn from the external environment or the ambient air supply system. To ensure that the regeneration air entering the air pretreatment system does not introduce external impurities, a pre-air filter is installed on the pipeline preceding the air inlet on the side to be heated of the heat exchanger 10. Ambient air from outside flows through this pre-air filter to remove dust and other mechanical impurities before being input into the heat exchanger 10 as clean ambient air to be heated. The air to be heated absorbs heat from the material inside the heat exchanger 10 and is then continuously and stably supplied as high-temperature regeneration air through the high-temperature regeneration air pipeline 9 to the regeneration zone 6 of the air pretreatment system for use in the cyclic desorption and regeneration of the adsorbent in the rotor 2.

[0051] In the above-mentioned fumed silica production system, a single air pretreatment system can simultaneously supply dry air to 2-5 reactors 100. The water-cooled temperature control mechanism 111 and heat exchanger 10 on the material conveying pipeline between each reactor 100 and the aggregator 200 can be connected in parallel to the regeneration zone 6 of the same air pretreatment system, realizing the waste heat recovery and air pretreatment functions of multi-furnace linkage, significantly improving energy utilization efficiency and equipment utilization rate.

[0052] The working process of this invention is as follows: Normal temperature and pressure air is purified by a blower and air filter 7 before entering the adsorption zone 5. The moisture in the air is adsorbed by the adsorbent in the rotor 2. The dried air (dew point ≤ -65℃) is transported to the reactor 100 through a pipeline to participate in the hydrolysis reaction.

[0053] The desorbed water wheel 2 rotates slowly under the drive of the drive mechanism and enters the regeneration zone 6. The high-temperature material at the outlet of the reactor 100 passes through the heat exchanger 10 of the reaction material pipeline, which heats the ambient air to 100℃-140℃ as regeneration air. This air is then sent into the regeneration zone 6 through the high-temperature regeneration air pipeline 9 to desorb the water from the adsorbent. The humid regeneration air is then discharged from the system through the exhaust pipeline 12.

[0054] When the temperature of the reactants rises and the regeneration air temperature exceeds 140℃, the cooling water valve of the water-cooled temperature control mechanism 111 is first opened to reduce the temperature of the material entering the heat exchanger 10 for coarse adjustment; at the same time, the venting regulating valve 112 is opened to vent some of the high-temperature hot air for fine adjustment, so that the regeneration air temperature is stabilized within the range of 100℃-140℃.

[0055] On the other hand, the present invention also provides a control method using the above-described air pretreatment system, comprising the following steps: Step 1: Adsorption and Dehumidification. After dust particles are removed from the outside air through the air filter 7, the outside air is sent into the adsorption zone 5 by the process fan 8. The air passes through the honeycomb channels of the rotor 2, where the moisture is adsorbed by the adsorbent; the dried pretreated air is output from the outlet of the adsorption zone 5, with a dew point below -40℃, and is sent into the reactor 100 as process air.

[0056] Step 2: As the rotor 2 rotates, the adsorbent sequentially undergoes desorption, deep regeneration, and cooling. The adsorbent that has adsorbed moisture rotates with the rotor 2, exiting from the adsorption zone 5 and sequentially entering the desorption zone 6a, the deep regeneration zone 6b, and the cooling zone 6c.

[0057] Step 3: Coarse Desorption and Preheating in the Desorption Zone. The adsorbent initially entering the desorption zone 6a has a temperature of 40-60℃ and a large amount of free water on its surface. At this time, the medium-temperature exhaust gas discharged from the deep regeneration zone 6b is introduced into the desorption zone 6a through the internal air duct 6e. First, the adsorbent temperature is rapidly increased through convection heat transfer. Once the adsorbent temperature rises above the exhaust gas dew point, the surface free water vaporizes and desorbs, completing the coarse desorption process. After coarse desorption, the water content of the adsorbent is significantly reduced; most of the free water is removed, leaving only bound water deep within the micropores. The hot, humid exhaust gas carrying the desorbed water is discharged from the outlet of the desorption zone 6a through the exhaust pipe 12.

[0058] Step 4: Deep Desorption in the Deep Regeneration Zone. The adsorbent, after coarse desorption, enters the deep regeneration zone 6b as the rotor 2 rotates. High-temperature regeneration air from heat exchanger 10 is introduced into the deep regeneration zone 6b to perform deep desorption of the adsorbent. The high-temperature air has a strong driving force for desorption, which can completely remove the bound water deep within the micropores of the adsorbent, restoring the adsorbent to near its initial adsorption capacity. The exhaust gas temperature from the deep regeneration zone 6b drops to 80-100℃ and is then sent to the desorption zone 6a through the internal air duct 6e for secondary heat utilization.

[0059] Step 5: Cooling in the cooling zone. The adsorbent, after deep regeneration, is at a high temperature. Directly entering the adsorption zone would result in insufficient adsorption capacity, leading to an unacceptable dew point. Therefore, the adsorbent rotates with rotor 2 into cooling zone 6c. Cooling fan 14 delivers ambient air to cooling zone 6c, exchanging heat with the high-temperature adsorbent to lower its temperature to 40-60℃, restoring its strong adsorption capacity. The cooled adsorbent then returns to adsorption zone 5 with rotor 2, beginning a new adsorption cycle.

[0060] Step Six: Adaptive Control. A temperature sensor monitors the regeneration air temperature entering the deep regeneration zone 6b in real time. When the air temperature falls below the set lower limit, indicating insufficient waste heat provided by heat exchanger 10 or significant fluctuations, the control system executes the following synchronous control based on the deviation between the air temperature and the median of the optimal temperature range: (1) Reduce the rotation speed of rotor 2 and prolong the residence time of adsorbent in each sub-region of the regeneration zone to ensure sufficient desorption under low wind temperature conditions; (2) Simultaneously reduce the operating frequency of the process air supply fan 8, reduce the processing air volume, reduce the adsorption load of the adsorbent, and make the regeneration capacity match the processing volume.

[0061] By synchronously adjusting the rotor speed and the process fan, the outlet dew point can be kept stable and up to standard under fluctuating waste heat conditions, ensuring the continuous and stable operation of the production system.

[0062] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. An air pretreatment system for the production of fumed silica, comprising: A sealing housing (1); a rotating wheel (2) disposed within the sealing housing (1); a sealing assembly (4) fitted to the end face of the rotating wheel (2); characterized in that, The sealing assembly (4) divides the end face of the rotating wheel (2) and the inner cavity of the sealing housing (1) into an independent adsorption zone (5) and a regeneration zone (6). The regeneration zone (6) is divided into a desorption zone (6a), a deep regeneration zone (6b) and a cooling zone (6c) in sequence by a partition (6f) along the rotation direction of the wheel (2). The exhaust outlet of the deep regeneration zone (6b) and the air inlet of the desorption zone (6a) are located on the same side of the rotor (2), and the two are connected by an internal air duct (6e) provided in the sealed housing (1). The air inlet of the deep regeneration zone (6b) is connected to the heat exchanger (10) of the reaction material pipeline of the fumed silica production system; the cooling zone (6c) is independently connected to the external ambient air.

2. The air pretreatment system according to claim 1, characterized in that, The sealed housing (1) corresponds to the internal space of the regeneration zone (6), and is divided into an end face sealing layer close to the rotor (2) and a back air duct layer away from the rotor (2) along the axial direction. The partition (6f) is disposed on the end face sealing layer and abuts against the wheel (2); the internal air duct (6e) is enclosed in the back air duct layer and is connected to the desorption zone (6a) and the deep regeneration zone (6b) respectively through the interface that penetrates the end face sealing layer.

3. The air pretreatment system according to claim 2, characterized in that, The internal air duct (6e) is formed by an arc-shaped air guide baffle and the end face sealing layer; the interface includes two openings that penetrate the end face sealing layer, which are respectively connected to the exhaust outlet of the deep regeneration zone (6b) and the air inlet of the desorption zone (6a).

4. The air pretreatment system according to claim 1, characterized in that, The sealing component (4) is made of polytetrafluoroethylene and includes an outer peripheral sealing ring (42) and several radial sealing strips (41). The several radial sealing strips (41) are arranged radially to correspondingly separate the adsorption area (5) and the regeneration area (6), and maintain an elastic contact with the end face of the rotating wheel (2) with a compression amount of 1mm-3mm.

5. The air pretreatment system according to claim 2, characterized in that, The ratio of the rotor end face area of ​​the adsorption zone (5) to that of the regeneration zone (6) is 2:1; within the regeneration zone (6), the ratio of the rotor end face area of ​​the desorption zone (6a) to that of the deep regeneration zone (6b) is 1:

1.

6. The air pretreatment system according to claim 1, characterized in that, An air filter (7) is connected to the air inlet of the adsorption zone (5), and a process air supply fan (8) is provided on the process air duct that is connected to the adsorption zone (5); the air outlets of the desorption zone (6a) and the cooling zone (6c) are respectively connected to a dehumidification duct (12).

7. The air pretreatment system according to claim 1, characterized in that, A temperature regulating device (11) is provided on the high temperature regeneration air duct leading to the deep regeneration zone (6b). The temperature regulating device (11) includes a water-cooled temperature control mechanism (111) provided on the preceding pipeline of the heat exchanger (10) and an vent regulating valve (112) provided on the high temperature regeneration air duct (9).

8. A fumed silica production system, comprising a reactor (100), an aggregator (200), a cyclone separator (300), and a deacidifier (400) connected in sequence, characterized in that, It also includes an air pretreatment system as described in any one of claims 1 to 7; the heat exchanger (10) is connected in series on the material conveying pipeline between the reactor (100) and the aggregator (200); the process air outlet of the air pretreatment system is connected to the reactor (100).

9. A control method for an air pretreatment system as described in any one of claims 1 to 7, characterized in that, Includes the following steps: The air to be treated is dehumidified by the adsorbent in the adsorption zone (5) and then output as pretreated air; After absorbing moisture, the adsorbent undergoes desorption, deep regeneration, and cooling in sequence. The desorption in the desorption zone (6a) is achieved by heating the exhaust gas in the deep regeneration zone (6b) that flows back through the internal air duct (6e); The deep regeneration is carried out in the deep regeneration zone (6b) by heating with a high-temperature heat source from the heat exchanger (10) of the reactant pipeline of the fumed silica production system for deep desorption; The cooling process involves introducing ambient temperature air into the cooling zone (6c). When the regeneration air temperature is below 100℃, the adsorbent decelerates with the rotor (2) to increase the residence time based on the deviation between the air temperature and the median of the optimal temperature range, and the frequency of the process air supply fan (8) is reduced simultaneously.

10. The control method for the air pretreatment system according to claim 9, characterized in that, The temperature of the high-temperature regeneration air introduced into the deep regeneration zone (6b) is 100℃-140℃, and the temperature of the humid and hot exhaust gas discharged from the desorption zone (6a) is 80℃-100℃.

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