CN-121988272-A - Continuous sol-gel reaction device for preparing nano silicon dioxide

CN121988272ACN 121988272 ACN121988272 ACN 121988272ACN-121988272-A

Abstract

The application relates to the technical field of nano material preparation, and discloses a continuous sol-gel reaction device for preparing nano silicon dioxide, which comprises a corrugated flexible liner, a constraint mechanism and a segmented rigid shell, wherein the corrugated flexible liner is used for containing and conveying reaction materials, the tube wall of the corrugated flexible liner is provided with outwards convex wave peak positions and inwards concave wave trough positions which are alternately distributed along the axial direction, the constraint mechanism is arranged outside the corrugated flexible liner and is used for applying radial displacement limitation to the wave trough positions of the corrugated flexible liner, and the segmented rigid shell is sleeved on the peripheries of the corrugated flexible liner and the constraint mechanism and consists of a plurality of annular tube sections which are axially arranged. The driving mechanism applies three-dimensional topological deformation which is strictly synchronous in radial compression, axial stretching and circumferential torsion on the corrugated flexible liner, and a complex Lagrange chaotic mixing field is forcedly constructed in the pipe, so that the instant uniform mixing of the reaction precursor and the catalyst on the microscopic scale is realized under the condition of not using an invasive stirrer.

Inventors

WANG XIUHUI
SUN MENGQI
CHANG CHAOXIA
YANG PENGSHAN

Assignees

东营一鸣新材料有限公司

Dates

Publication Date: 20260508
Application Date: 20260202

Claims (9)

1. A continuous sol-gel reaction device for preparing nano silicon dioxide, which is characterized by comprising: the corrugated flexible liner (1) is used for containing and conveying reaction materials, and the pipe wall of the corrugated flexible liner (1) is provided with outwards convex crest positions and inwards concave trough positions which are alternately distributed along the axial direction; the constraint mechanism is arranged outside the corrugated flexible liner (1) and is used for applying radial displacement limitation to the trough position of the corrugated flexible liner (1); The sectional rigid shell (2) is sleeved on the periphery of the corrugated flexible liner (1) and the constraint mechanism and consists of a plurality of annular barrel sections (201) which are axially arranged, and the inner walls of the annular barrel sections (201) are fixedly connected with the wall of part of the wave crest position of the corrugated flexible liner (1) respectively; the driving mechanism is used for applying periodic radial extrusion force to the wave crest position, and driving the corrugated flexible liner (1) to generate axial telescopic deformation in cooperation with the limiting action of the constraint mechanism, and driving the adjacent annular barrel sections (201) to generate relative rotation so as to drive the corrugated flexible liner (1) to generate circumferential torsional deformation; The constant temperature immersion box (3), the inside of constant temperature immersion box (3) is filled with heat conduction silicone oil, the whole submergence of ripple flexible inner bag (1), sectional type rigid housing (2) and actuating member of actuating mechanism is in heat conduction silicone oil.
2. The continuous sol-gel reaction device for preparing nano silicon dioxide according to claim 1, wherein the constraint mechanism comprises a plurality of floating slip rings (4) which are independently arranged, the floating slip rings (4) are nested on the trough positions of the corrugated flexible liner (1), and the inner diameter of the floating slip rings (4) is matched with the outer diameter of the trough positions, so as to lock the radial freedom degree of the trough positions and guide the corrugated flexible liner (1) to extend along the axial direction.
3. The continuous sol-gel reaction device for preparing nano silicon dioxide according to claim 2, wherein the annular barrel section (201) coaxially surrounds the outside of the floating slip ring (4), an annular avoidance gap is reserved between the inner wall surface of the annular barrel section (201) and the outer circumferential surface of the floating slip ring (4), and the annular avoidance gap is used for filling a fluid medium to form a lubricating film, so that the floating slip ring (4) performs axial sliding and following rotation independently of the annular barrel section (201).
4. The continuous sol-gel reaction device for preparing nano silicon dioxide according to claim 1, wherein the driving mechanism comprises a main driving shaft (5) and an eccentric cam array fixed on the main driving shaft (5), the eccentric cam array is composed of a plurality of eccentric cams (6) distributed along the axial direction, the working profile surface of each eccentric cam (6) is directly abutted to the crest position of the corrugated flexible liner (1), and a phase gradient is arranged between every two adjacent eccentric cams (6) to enable the corrugated flexible liner (1) to form peristaltic wave deformation in the axial direction.
5. The continuous sol-gel reaction device for preparing nano silicon dioxide according to claim 4, wherein the driving mechanism further comprises a differential incomplete gear set, the differential incomplete gear set comprises a plurality of driving gear plates (7) and driven gear rings (8) fixed on the periphery of the annular barrel section (201), the driving gear plates (7) are of non-full-tooth circumferential structures and are used for periodically meshing the driven gear rings (8), the annular barrel section (201) is driven to perform discontinuous pulse rotation, and meshing phase differences are arranged among different driving gear plates (7).
6. The continuous sol-gel reaction device for preparing nano silicon dioxide according to claim 5, wherein the eccentric cam array and the differential incomplete gear set are respectively distributed on the main driving shaft (5) correspondingly in preset phases, when the radial extrusion stroke of the eccentric cam (6) to the peak position reaches the maximum value, the corresponding differential incomplete gear set drives the annular barrel section (201) to rotate to the maximum torsion angle, so that a three-dimensional topological stress field with instantaneous superposition of radial compression, axial stretching and circumferential torsion is formed on the pipe wall of the corrugated flexible liner (1).
7. A continuous sol-gel reaction apparatus for the preparation of nanosilica according to claim 1, characterized in that adjacent two annular cylinder segments (201) are connected by a rolling bearing assembly (202) to maintain axial position fixed and allow relative rotation in circumferential direction.
8. The continuous sol-gel reaction device for preparing nano silicon dioxide according to claim 4, wherein a riding wheel array (9) is arranged on the inner bottom wall of the constant temperature immersion box (3), the riding wheel array (9) and buoyancy of heat conduction silicone oil jointly act to support the segmented rigid shell (2) in a rolling way, a servo motor (10) is fixedly connected to the outer wall of the constant temperature immersion box (3), and the main driving shaft (5) penetrates through the box wall of the constant temperature immersion box (3) through a magnetic fluid sealing assembly and is fixedly connected with the driving end of the servo motor (10).
9. The continuous sol-gel reaction device for preparing nano silicon dioxide according to claim 1, wherein the feeding end of the corrugated flexible liner (1) is sealed and fixedly connected with a cyclone distribution assembly (11), the cyclone distribution assembly (11) is also immersed in heat-conducting silicone oil, and a spiral diversion trench is formed in the cyclone distribution assembly (11) and is used for converting an input reaction precursor into tangential cyclone and forming a coaxial laminar flow wrapping state before entering the corrugated flexible liner (1).

Description

Continuous sol-gel reaction device for preparing nano silicon dioxide Technical Field The invention relates to the technical field of nano material preparation, in particular to a continuous sol-gel reaction device for preparing nano silicon dioxide. Background The nano silicon dioxide is used as an extremely important inorganic functional material, and is widely applied to the front fields of rubber reinforcement, CMP polishing solution, resin matrix composite materials, biological medicine carriers and the like because of the high specific surface area, good chemical stability and unique optical characteristics. At present, a liquid phase sol-gel method is a mainstream process for preparing monodisperse and high-purity nano silicon dioxide. The process involves hydrolysis and polycondensation of a silicon source precursor (e.g., ethyl orthosilicate) and is characterized in that the reaction system undergoes a sharp phase change from a low viscosity newtonian fluid to a high viscosity non-newtonian fluid, or even to a semi-solid gel network. This variation in rheological properties, spanning several orders of magnitude, places very challenging engineering demands on the thermal mass transfer performance of the reaction equipment. In the existing industrial production, the traditional kettle type batch reactor still takes the dominant role. However, with increasing demands on nanoparticle particle size uniformity, the inherent drawbacks of tank reactors are increasingly pronounced. Since the sol-gel reaction is a strongly exothermic and extremely temperature sensitive process, the viscosity of the system rapidly rises as the polymerization proceeds, resulting in a rapid decrease in the flowability of the fluid in the tank. Under the action of conventional stirring paddles, high viscosity fluids are very prone to form "flow dead zones" or "isolation pockets" in regions remote from the paddles, causing localized heat transfer deterioration and concentration polarization. This non-uniformity of thermodynamic and kinetic environments directly leads to a broadening of the product particle size distribution and a difficult control of the mass stability from batch to batch. In addition, auxiliary working hours (feeding, discharging and cleaning) which are inevitably brought by intermittent operation also severely restrict the improvement of production efficiency. To solve the above problems, researchers have begun to attempt to introduce continuous flow tube microchannel reactors. Theoretically, the high specific surface area of the microchannels can provide excellent heat transfer efficiency and precise residence time control. However, in practical sol-gel production, tubular reactors face a fatal technical bottleneck, wall fouling and flow channel plugging. In the nucleation and growth stage, the high-activity siloxane oligomer is easily adsorbed on the wall of the reaction tube, and a hard silica scale layer is formed by continuously growing on the reaction tube as a substrate. The silicon scale layer not only greatly increases heat conduction resistance and damages the temperature control precision of the reactor, but also reduces the effective section of the flow channel to cause the exponential rise of the back pressure of the system, and finally forces the device to stop for cleaning. To mitigate fouling, prior art solutions typically employ built-in static mixers to enhance fluid turbulence, although this improves radial mixing to some extent, the complex geometry of static mixers provides just more attachment sites for the gel, rather accelerating the occurrence of clogging. In addition, some of the technologies have attempted to employ flexible tube reactors based on peristaltic pump principles in an attempt to strip scale by extrusion deformation of the tube walls. However, conventional peristaltic extrusion merely pushes the fluid in the axial direction, the fluid remains in a laminar state within the tube, and lack of a deep mixing mechanism in the radial direction results in uneven mixing of the reaction materials in the cross section, and the "penetration" phenomenon is serious. More critical is that the existing flexible reactor is usually exposed in the air, and lacks an efficient thermal management system, when high-frequency mechanical extrusion is carried out, heat generated by viscous dissipation in the flexible pipe cannot be removed in time, local temperature runaway is extremely easy to cause, the product quality is affected, and thermal fatigue failure of the high-polymer pipe is accelerated. Disclosure of Invention Aiming at the defects of the prior art, the invention provides a continuous sol-gel reaction device for preparing nano silicon dioxide, which solves the technical problems that the existing tubular reactor is easy to generate wall surface scaling and blocking, has low radial mixing efficiency and uneven control of a reaction temperature field in the high-viscosity sol-gel react