Equipment for preparing amorphous nano-spherical silicon dioxide

Abstract

The invention discloses a device for preparing amorphous nanometer spherical silicon dioxide, comprising: a silicon tetrachloride feeding device, a radio frequency plasma generator, a synthesis chamber, a cooling chamber, a first collecting chamber, a first separator, a second collecting chamber, a second separator, a third collecting chamber, a vacuum unit and a chlorine recovery device; the silicon tetrachloride feeding device is used to provide gaseous silicon tetrachloride; the radio frequency plasma generator is connected to the synthesis chamber; the cooling chamber is connected to the synthesis chamber, and the first collecting chamber is connected to the cooling chamber; the first separator is connected to the cooling chamber through a pipeline, and the second collecting chamber is connected to the first separator; the second separator is connected to the first separator, and the third collecting chamber is connected to the second separator; the chlorine recovery device is connected to the second separator through a pipeline; the vacuum unit is connected to the pipeline between the second separator and the chlorine recovery device. The above-mentioned device can efficiently prepare amorphous nanometer spherical silicon dioxide.

Description

Technical Field

[0001] The invention relates to the technical field of powder metallurgy, in particular to a device for preparing amorphous nano spherical silicon dioxide. Background Art

[0002] Materials science and technology is one of the three pillars of contemporary civilization and one of the three signs of the global new technological revolution. It plays a fundamental and leading role in the development of today's high technology. The ultra-fine processing of various substances is considered to be the basis of materials development and research.

[0003] Nano-silicon dioxide is one of the most advanced materials with the largest output, the highest output value and the widest application in the new materials of the 21st century. Nano-silicon dioxide powder has small size effect, surface interface effect, quantum size effect and macro quantum tunneling effect, showing optical, electrical, magnetic, thermal and mechanical properties that conventional materials do not have. Therefore, it is widely used in many fields such as optics, chemical industry and special ceramics as a new functional material. In particular, amorphous nano-spherical silicon dioxide powder has excellent properties such as high strength, high hardness, wear resistance, abrasion resistance, corrosion resistance, high temperature resistance, oxidation resistance, good insulation and large surface area, so amorphous nano-spherical silicon dioxide has special uses in catalysis, flame retardancy, sound insulation, insulation, fine ceramics and so on.

[0004] The Chinese patent with the publication number CN103224240B discloses a method for synthesizing nano-sized silicon dioxide by gas phase hydrolysis of silicon tetrachloride, and the method adopts gas phase hydrolysis synthesis method to prepare nano-sized silicon dioxide. The Chinese patent with the publication number CN104477923A discloses a method for preparing silicon dioxide powder from silicon tetrachloride, and the method adopts chemical precipitation method to prepare silicon dioxide powder. The Chinese patent with the publication number CN102656117B discloses a synthetic amorphous silicon dioxide powder and a method for manufacturing the same, and the amorphous silicon dioxide powder is prepared by preparing a silicon dioxide gel.

[0005] The Chinese patent with the announcement number CN1281488C discloses a method for preparing nanometer high-purity silicon dioxide, and the method adopts a plasma gas phase oxidation reaction device to prepare nanometer high-purity silicon dioxide, and the plasma gas phase oxidation reaction device mainly includes a plasma generator, a plasma chemical reactor, a scar removal device, a cooling system, a collecting system, a powder treatment system and a tail gas treatment system, and the silicon dioxide prepared by the above-mentioned device passes through the cooling system and the collecting system in turn under the action of the working gas, and the Cl2 gas produced is absorbed by alkali solution, lime milk or iron filings to produce byproducts, and the remaining waste gas (O2, N2) is emptied. The problem existing in the above-mentioned method is that the silicon dioxide prepared flows under the driving effect of the working gas, and it is easy to block the reactor, and the preparation efficiency is low, and the chlorine produced is absorbed by alkali solution, lime milk or iron filings, and there is insufficient absorption on the one hand, resulting in the problem of partial chlorine emptying and polluting the air, and on the other hand, the chlorine produced is directly absorbed and cannot be reused by heavy division.

[0006] Therefore, it is of great significance to study how to efficiently prepare amorphous nano-spherical silica and improve the utilization rate of exhaust gas. Summary of the invention

[0007] The present invention provides a device for preparing amorphous nanometer spherical silicon dioxide to solve the above problem. The device can efficiently prepare amorphous nanometer spherical silicon dioxide and can directly recycle the generated chlorine.

[0008] The present invention is implemented by the following technical solutions:

[0009] A device for preparing amorphous nano-spherical silicon dioxide, comprising: a silicon tetrachloride feeding device, a radio frequency plasma generator, a synthesis chamber, a cooling chamber, a first collecting chamber, a first separator, a second collecting chamber, a second separator, a third collecting chamber, a vacuum unit and a chlorine recovery device;

[0010] The silicon tetrachloride feeding device is used to provide gaseous silicon tetrachloride; the radio frequency plasma generator is connected to the synthesis chamber to form a high-temperature plasma torch in the synthesis chamber, and the gaseous silicon tetrachloride provided by the silicon tetrachloride feeding device reacts with oxygen in the synthesis chamber under the action of the high-temperature plasma torch to generate silicon dioxide; the cooling chamber is connected to the synthesis chamber to cool the generated silicon dioxide, and the first collecting chamber is connected to the cooling chamber to receive part of the silicon dioxide; the first separator is connected to the cooling chamber through a pipeline to receive and separate part of the silicon dioxide, and the second collecting chamber is connected to the first separator to receive the silicon dioxide separated by the first separator; the second separator is connected to the first separator to receive and separate part of the silicon dioxide, and the third collecting chamber is connected to the second separator to receive the silicon dioxide separated by the second separator; the chlorine recovery device is connected to the second separator through a pipeline to separate and recover the generated chlorine; the vacuum unit is connected to the pipeline between the second separator and the chlorine recovery device to evacuate the equipment for preparing amorphous nano spherical silicon dioxide.

[0011] Preferably, the silicon tetrachloride feeding device comprises: a silicon tetrachloride storage tank, a delivery pump, a first buffer tank and a heating mechanism;

[0012] The silicon tetrachloride storage tank is used to store liquid silicon tetrachloride. The delivery pump is connected to the silicon tetrachloride storage tank and the first buffer tank through pipelines. The delivery pump is used to deliver the silicon tetrachloride in the silicon tetrachloride storage tank into the first buffer tank. The heating mechanism is used to heat the pipeline between the delivery pump and the first buffer tank to vaporize the liquid silicon tetrachloride in the pipeline, and the gaseous silicon tetrachloride is delivered out of the first buffer tank.

[0013] Preferably, the heating mechanism comprises a heating oil bath for heating the pipeline between the delivery pump and the first buffer tank.

[0014] Preferably, the silicon tetrachloride feeding device also includes a reflux pipeline, the two ends of which are respectively connected to the pipeline between the silicon tetrachloride storage tank and the delivery pump and the pipeline between the delivery pump and the first buffer tank, and the reflux pipeline is used to reflux unvaporized silicon tetrachloride in the pipeline between the delivery pump and the first buffer tank to the pipeline between the silicon tetrachloride storage tank and the delivery pump.

[0015] Preferably, the silicon tetrachloride feeding device further comprises a desiccant tank for storing an acidic desiccant, and the desiccant tank is connected to the top of the inner cavity of the silicon tetrachloride storage tank through a pipeline.

[0016] Preferably, the first collecting chamber is arranged below the cooling chamber to collect micron-sized silicon dioxide powder;

[0017] The first separator is a cyclone separator, and the second collecting chamber is arranged below the first separator to collect quasi-nanoscale silicon dioxide powder;

[0018] The second separator is a bag separator, and the third collecting chamber is arranged below the second separator to collect nano-scale silicon dioxide powder.

[0019] Preferably, the chlorine recovery device comprises: a mixed gas buffer tank, a compressor, a liquid chlorine separation tank, a second buffer tank and an alkali solution tank;

[0020] The mixed gas buffer tank is used to receive and store a mixed gas containing chlorine. The compressor is connected to the mixed gas buffer tank and the liquid chlorine separation tank through pipelines. The compressor is used to compress the mixed gas discharged from the mixed gas buffer tank to compress the chlorine into liquid and send it to the liquid chlorine separation tank through a pipeline. The liquid chlorine separation tank is used to store liquid chlorine. The second buffer tank is connected to the liquid chlorine separation tank so that uncompressed mixed gas flows from the liquid chlorine separation tank to the second buffer tank. The second buffer tank is connected to the alkali liquid tank through a pipeline so that the gas discharged from the second buffer tank flows to the alkali liquid tank and absorbs the acidic gas.

[0021] Preferably, the mixed gas buffer tank includes a tank body and an elliptical head arranged on the top of the tank body, the elliptical head includes an inner elliptical head and an outer elliptical head, the outer elliptical head is floatingly arranged outside the inner elliptical head, and hydraulic oil is arranged between the lower edge of the inner elliptical head and the lower edge of the outer elliptical head.

[0022] Preferably, the mixed gas buffer tank is provided with an overflow port, the overflow port is connected to an absorption tank through a pipeline, and the alkaline solution in the absorption tank is used to absorb the acidic gas in the mixed gas overflowing from the mixed gas buffer tank.

[0023] Preferably, the chlorine recovery device further comprises a balance pressure pipe, and two ends of the balance pressure pipe are respectively connected to the pipeline between the mixed gas buffer tank and the compressor and the pipeline between the compressor and the liquid chlorine separation tank.

[0024] Compared with the prior art, the beneficial effects of the present invention include at least:

[0025] The equipment for preparing amorphous nanometer spherical silicon dioxide of the present invention comprises a silicon tetrachloride feeding device, a radio frequency plasma generator, a synthesis chamber, a cooling chamber, a first collecting chamber, a first separator, a second collecting chamber, a second separator, a third collecting chamber, a vacuum unit and a chlorine recovery device. The generated amorphous nanometer spherical silicon dioxide is effectively screened into silicon dioxide powders of different particle sizes under the action of the exhaust power of the vacuum unit, and micron-level silicon dioxide powders, quasi-nanometer-level silicon dioxide powders and nanometer-level silicon dioxide powders are respectively collected in the first collecting chamber, the second collecting chamber and the third collecting chamber. The preparation efficiency is higher, and the chlorine recovery device can directly recover the generated chlorine. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the structure of an apparatus for preparing amorphous nano-spherical silicon dioxide according to an embodiment of the present invention.

[0027] Figure 2 It is a schematic structural diagram of a silicon tetrachloride feeding device according to an embodiment of the present invention.

[0028] Figure 3 It is a schematic diagram of the connection structure with a partial cross section of the radio frequency plasma generator and the synthesis chamber according to an embodiment of the present invention.

[0029] Figure 4 It is a schematic structural diagram with a partial cross section of the first separator of an embodiment of the present invention.

[0030] Figure 5 It is a schematic structural diagram with a partial cross section of the second separator according to an embodiment of the present invention.

[0031] Figure 6 It is a schematic diagram of the principle of a chlorine recovery device according to an embodiment of the present invention.

[0032] Figure 7 It is a schematic structural diagram of a chlorine recovery device according to an embodiment of the present invention.

[0033] Figure 8 1 is a transmission electron microscope (TEM) image of amorphous nano-spherical silicon dioxide prepared according to the device and method of an embodiment of the present invention.

[0034] Fig. 9 The figure is an X-ray diffraction pattern (XRD) of amorphous nano-spherical silica prepared by the device and method according to the embodiment of the present invention.

[0035] Fig.10 It is a schematic flow chart of a method for preparing amorphous nano-spherical silicon dioxide according to an embodiment of the present invention.

[0036] In the figure: 10, silicon tetrachloride feeding device; 11, silicon tetrachloride storage tank; 12, delivery pump; 13, first buffer tank; 14, heating mechanism; 15, desiccant tank; 16, reflux pipeline; 20, radio frequency plasma generator; 30, synthesis chamber; 40, cooling chamber; 50, first collection chamber; 61, first separator; 611, straight cylinder; 612, cone; 613, volute; 614, feed port; 62, second collection chamber; 71, second separator; 711, shell ; 7111, feed inlet; 7112, exhaust port; 712, collecting cone hopper; 713, bag frame; 714, air bag; 715, control valve; 716, backflush nozzle; 72, third collecting chamber; 80, vacuum unit; 90, chlorine recovery device; 91, mixed gas buffer tank; 911, tank body; 912, elliptical head; 92, compressor; 93, liquid chlorine separation tank; 94, second buffer tank; 95, alkali solution tank; 96, balance pressure pipe; 100, pipeline. DETAILED DESCRIPTION

[0037] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided to make the present invention more comprehensive and complete and to fully convey the concepts of example embodiments to those skilled in the art. The same reference numerals in the figures represent the same or similar structures, and thus their repeated description will be omitted.

[0038] The words expressing positions and directions described in the present invention are all explained with reference to the accompanying drawings as examples, but they can be changed as needed, and all such changes are included in the protection scope of the present invention.

[0039] See also Figures 1 to 7 An embodiment of the present invention provides an apparatus for preparing amorphous nano-spherical silicon dioxide, the apparatus comprising: a silicon tetrachloride feeding device 10, a radio frequency plasma generator 20, a synthesis chamber 30, a cooling chamber 40, a first collecting chamber 50, a first separator 61, a second collecting chamber 62, a second separator 71, a third collecting chamber 72, a vacuum unit 80 and a chlorine recovery device 90, and further comprising a pipeline 100.

[0040] Reference Figure 2 The silicon tetrachloride feeding device 10 is used to provide gaseous silicon tetrachloride. The silicon tetrachloride feeding device 10 includes: a silicon tetrachloride storage tank 11, a delivery pump 12, a first buffer tank 13 and a heating mechanism 14, and further includes a desiccant tank 15 and a reflux pipeline 16.

[0041] Specifically, the silicon tetrachloride storage tank 11 is used to store liquid silicon tetrachloride. The silicon tetrachloride storage tank 11 is, for example, a 1400L storage tank. The silicon tetrachloride storage tank 11 has an outlet for discharging liquid silicon tetrachloride, and the outlet can be located at the bottom of the silicon tetrachloride storage tank 11. The delivery pump 12 is connected to the silicon tetrachloride storage tank 11 and the first buffer tank 13 through a pipeline 100. The delivery pump 12 is used to deliver the silicon tetrachloride in the silicon tetrachloride storage tank 11 to the first buffer tank 13. The delivery pump 12 can be a micro-boosting pump. The delivery pump 12 has an inlet for silicon tetrachloride to enter and an outlet for silicon tetrachloride to be discharged. The inlet of the delivery pump 12 is connected to the outlet of the silicon tetrachloride storage tank 11 through the pipeline 100, and the outlet of the delivery pump 12 is connected to the inlet of the first buffer tank 13 through the pipeline 100.

[0042] The heating mechanism 14 is used to heat the pipeline 100 between the delivery pump 12 and the first buffer tank 13 to vaporize the liquid silicon tetrachloride in the pipeline 100. As a preferred embodiment, the heating mechanism 14 includes a heating oil bath for heating the pipeline 100 between the delivery pump 12 and the first buffer tank 13. The heating oil bath can heat a part of the pipeline 100 between the delivery pump 12 and the first buffer tank 13. The heating oil bath has the advantage of being able to accurately control the temperature. The heating temperature of the heating oil bath is preferably 60-80°C. Under the heating effect of the heating oil bath, the colorless and transparent liquid silicon tetrachloride is safely and quickly vaporized into gaseous silicon tetrachloride, and the gaseous silicon tetrachloride flows into the first buffer tank 13 through the pipeline 100. The first buffer tank 13 is, for example, a 10L storage tank. An outlet is provided at the top of the first buffer tank 13. The gaseous silicon tetrachloride is sent out from the outlet of the first buffer tank 13 and flows to the radio frequency plasma generator 20 and the synthesis chamber 30 for reaction.

[0043] In some embodiments of the present invention, the silicon tetrachloride feeding device 10 further includes a desiccant tank 15 for storing an acidic desiccant, and the desiccant tank 15 is connected to the top of the inner cavity of the silicon tetrachloride storage tank 11 through a pipeline 100. The water vapor in the air in the silicon tetrachloride storage tank 11 easily decomposes the silicon tetrachloride, and the silicon tetrachloride produces silicic acid and hydrogen chloride after decomposition. By providing the desiccant tank 15, the acidic desiccant in the desiccant tank 15 can absorb the water vapor in the silicon tetrachloride storage tank 11, thereby reducing and preventing the decomposition of silicon tetrachloride, ensuring that the liquid silicon tetrachloride stored in the silicon tetrachloride storage tank 11 has a high purity, which is conducive to the subsequent production of high-purity amorphous nano-spherical silicon dioxide.

[0044] In some embodiments of the present invention, the silicon tetrachloride feeding device 10 also includes a reflux pipeline 16, and the two ends of the reflux pipeline 16 are respectively connected to the pipeline 100 between the silicon tetrachloride storage tank 11 and the delivery pump 12 and the pipeline 100 between the delivery pump 12 and the first buffer tank 13. The reflux pipeline 16 is used to reflux the unvaporized silicon tetrachloride in the pipeline 100 between the delivery pump 12 and the first buffer tank 13 to the pipeline 100 between the silicon tetrachloride storage tank 11 and the delivery pump 12. Specifically, when the liquid silicon tetrachloride in the pipeline 100 between the delivery pump 12 and the first buffer tank 13 is not completely vaporized by the heating mechanism 14, the unvaporized silicon tetrachloride in the pipeline 100 between the delivery pump 12 and the first buffer tank 13 can be refluxed to the pipeline 100 between the silicon tetrachloride storage tank 11 and the delivery pump 12 through the reflux pipeline 16, and can be transported to the pipeline 100 between the delivery pump 12 and the first buffer tank 13 for heating and vaporization through the delivery pump 12. By setting the reflux pipeline 16, it is possible to prevent the unvaporized silicon tetrachloride from accumulating in the pipeline 100 between the delivery pump 12 and the first buffer tank 13 and flowing into the first buffer tank 13, thereby ensuring that the first buffer tank 13 is filled with gaseous silicon tetrachloride.

[0045] Reference Figure 3 The radio frequency plasma generator 20 is connected to the synthesis chamber 30 to form a high-temperature plasma torch in the synthesis chamber 30. The gaseous silicon tetrachloride provided by the silicon tetrachloride feeding device 10 reacts with oxygen in the synthesis chamber 30 to generate silicon dioxide under the action of the high-temperature plasma torch.

[0046] Specifically, the gaseous silicon tetrachloride sent out from the first buffer tank 13 enters the synthesis chamber 30 under the carrying effect of argon gas, the working gas of the radio frequency plasma generator 20 is oxygen, and the radio frequency plasma generator 20 forms a high-temperature plasma torch in the synthesis chamber 30. The temperature of the high-temperature plasma torch is as high as tens of thousands of degrees Celsius. A large number of oxygen molecules are quickly cracked into oxygen atoms in the high-temperature zone of the high-temperature plasma torch. In the reaction, oxygen mainly participates in the replacement reaction in the plasma state. The reaction formula is as follows. These cracked oxygen atoms have strong high-temperature activity, which can greatly improve the reaction process, and will quickly undergo a replacement reaction with silicon tetrachloride to form liquid nano silicon dioxide. In addition, the amorphous transformation of silicon dioxide powder is achieved in the local high temperature environment in the synthesis chamber 30. Since the high-temperature plasma torch itself has inevitable electromagnetic contraction asymmetry, air flow turbulence and cross-flow phenomenon, a very small part of the liquid nano silicon dioxide is bonded into agglomerates to form part of micron-sized silicon dioxide powder and quasi-nano-sized silicon dioxide powder. Therefore, it is necessary to collect the micron-sized silicon dioxide powder and quasi-nano-sized silicon dioxide powder separately to improve the purity of the collected nano-sized silicon dioxide powder.

[0047] SiCl4 (gaseous) + O2 (plasma) = SiO2 (solid) + 2Cl2 (gaseous)

[0048] The cooling chamber 40 is connected to the synthesis chamber 30 to cool the generated silicon dioxide, and the first collection chamber 50 is connected to the cooling chamber 40 to receive part of the silicon dioxide. In order to improve the ability to resist crevice corrosion in a medium with high chloride ion concentration, the cooling chamber 40 adopts a water-cooled double-layer Ti-0.2Pd alloy cold-drawn seamless tube. Since the titanium alloy material has the characteristics of high strength, good corrosion resistance, and high heat resistance, it can withstand the corrosion of the generated chlorine. The first collection chamber 50 is located below the cooling chamber 40. Part of the silicon dioxide formed after the cooling chamber 40 is cooled enters the first collection chamber 50. The first collection chamber 50 can be used to collect micron-sized silicon dioxide powder. The average particle size of the micron-sized silicon dioxide powder collected by the first collection chamber 50 is, for example, about 0.1μm.

[0049] Continue to refer to Figure 1 The first separator 61 is connected to the cooling chamber 40 through the pipeline 100 to receive and separate part of the silicon dioxide, and the second collection chamber 62 is connected to the first separator 61 to receive the silicon dioxide separated by the first separator 61. Specifically, under the vacuuming action of the vacuum unit 80, the gas carries part of the generated silicon dioxide powder from the cooling chamber 40 to the first separator 61. The first separator 61 is preferably a cyclone separator. The first separator 61 separates part of the silicon dioxide. The silicon dioxide separated by the first separator 61 is preferably quasi-nano-scale silicon dioxide powder. The average particle size of the quasi-nano-scale silicon dioxide powder is, for example, about 100 nm. The second collection chamber 62 is arranged below the first separator 61 to collect the quasi-nano-scale silicon dioxide powder.

[0050] Reference Figure 4 The cyclone separator mainly includes a straight cylinder 611, a cone 612 and a volute 613. The cyclone separator has the advantages of high temperature resistance, high pressure, simple structure, no moving parts, and low cost. In some embodiments of the present invention, a feed port 614 is set at the upper end of the cyclone separator. First, the gas-powder mixture formed by the chlorine-containing mixed gas and the silicon dioxide powder enters the feed air distribution chamber of the cyclone separator from the feed port 614, and after the collision and deflection of the cyclone branch pipe, the air flow is evenly distributed and flows to the cyclone air inlet. The evenly distributed air flow enters the cyclone from the tangential direction, and the gas forms a cyclonic airflow in the cyclone tube. The strong centrifugal force causes the solid particles in the gas to be thrown out and gathered on the inner wall of the cyclone tube, and finally falls into the second collection chamber 62 for collecting quasi-nano-scale silicon dioxide powder, while the nano-scale silicon dioxide powder and the chlorine-containing mixed gas-powder mixture continue to rise vertically along the axis to the exhaust port and flow out of the cyclone separator.

[0051] In some embodiments of the present invention, by setting a feed port 614 at the upper end of the cyclone separator, shortening the cone 612 part of its cylindrical cone structure and lengthening the straight cylinder 611 part, the length of the cone 612 part is preferably 70-80cm, and the length of the straight cylinder 611 part is preferably 28-30cm, which not only improves the separation efficiency, but also effectively avoids the interaction between the inner vortex and the outer vortex in the traditional cyclone separator, resulting in the minimum static pressure at the air core of the cyclone separator, or even negative pressure, which may cause the airflow to be mixed in the second collection chamber 62 for collecting quasi-nano-scale silica powder. The above-mentioned improved cyclone separator structure can remove quasi-nano-scale silica powder in the conveying gas as much as possible while saving materials, thereby improving the purity of the nano-scale silica powder collected subsequently.

[0052] Continue to refer to Figure 1 The second separator 71 is connected to the first separator 61 to receive and separate part of the silicon dioxide, and the third collection chamber 72 is connected to the second separator 71 to receive the silicon dioxide separated by the second separator 71. Specifically, under the vacuuming action of the vacuum unit 80, the gas carries part of the generated silicon dioxide powder from the first separator 61 to the second separator 71. The second separator 71 is preferably a bag separator. The second separator 71 separates part of the silicon dioxide. The silicon dioxide separated by the second separator 71 is preferably nano-scale silicon dioxide powder. The average particle size of the nano-scale silicon dioxide powder is, for example, about 10 nm. The third collection chamber 72 is arranged below the second separator 71 to collect the nano-scale silicon dioxide powder.

[0053] Reference Figure 5 The bag separator mainly includes a shell 711, a collecting cone hopper 712 connected to the bottom of the shell 711, a plurality of bag frames 713 arranged in the shell 711, a back-blowing mechanism, etc. A feed port 7111 is arranged at the upper part of the shell 711, and an exhaust port 7112 is arranged at the lower part of the shell 711.

[0054] The bag frame 713 is used to install the filter bag (not shown). The bag frame 713 of the embodiment of the present invention is preferably a stainless steel bag frame 713. The stainless steel bag frame 713 is the rib of the filter bag. It uses stainless steel wire with sufficient strength and rigidity, and uses a high-frequency welder to weld the frame in one step to form the frame. The stainless steel bag frame 713 adopts a circular structure, and the longitudinal ribs and anti-support rings of the bag cage are evenly distributed and have sufficient strength and rigidity to prevent damage and deformation. This stainless steel bag frame 713 has the characteristics of corrosion resistance, high temperature resistance, easy installation and maintenance, light, smooth, straight, strong frame, no weld nodules and burrs at the frame welding, and long service life of the stainless steel bag frame 713.

[0055] The back-blowing mechanism mainly includes an air bag 714, a control valve 715 and a back-blowing nozzle 716, etc. The function of the back-blowing mechanism is to remove the nano-scale silicon dioxide powder adsorbed on the outer surface of the filter bag under the action of the vacuum unit 80 of the entire equipment. A back-blowing nozzle 716 is installed at the top of the outlet of each row of filter bags in the filter chamber of the housing 711. A back-blowing port is provided at the lower side of the back-blowing nozzle 716 facing the center of the filter bag. Each back-blowing nozzle 716 is provided with an electromagnetic pulse control valve 715 and is connected to the air bag 714 filled with compressed air. When the back-blowing cleaning is in operation, the control valve 715 is opened, and the compressed air opens the electromagnetic pulse back-blowing according to the set program. The compressed gas passes through each control valve 715 in sequence in a very short time and passes through the nozzle on the back-blowing nozzle 716, generating air several times the amount of the injected gas to enter the filter bag, forming an air wave, causing the filter bag to expand rapidly and vibrate from the bag mouth to the bottom, resulting in a strong cleaning effect, and shaking off the silicon dioxide powder on the filter bag. The nano-scale silica powder separated by the bag separator is collected by the third collection chamber 72, the micron-scale silica powder is collected by the first collection chamber 50, and the quasi-nano-scale silica powder is separated and collected by the first separator 61 and the second collection chamber 62. The bag separator and the third collection chamber 72 can collect up to 98% of the silica powder generated by the equipment, and this part of the silica powder is nano-scale powder with an average particle size of about 10nm. Figure 8 As shown in the transmission electron microscope image, the size of the nano-scale silicon dioxide powder prepared and separated does not exceed 15nm, the microscopic morphology is spherical, and there is obvious agglomeration. Fig. 9 As shown in (X-ray diffraction pattern), in the diffraction pattern of the prepared and separated nano-scale silicon dioxide powder, only one bun peak, i.e., an amorphous diffraction peak, appears in the low diffraction angle region of 20°-28°, thereby determining that the obtained nano-scale silicon dioxide is an amorphous substance.

[0056] Continue to refer to Figure 1 The vacuum unit 80 is connected to the pipeline 100 between the second separator 71 and the chlorine recovery device 90 to evacuate the equipment for preparing amorphous nano-spherical silicon dioxide. The vacuum unit 80 may include a rotary vane vacuum pump, a roots vacuum pump, and an oil diffusion vacuum pump.

[0057] Reference Figure 6 and Figure 7 The chlorine recovery device 90 is connected to the second separator 71 through a pipeline 100 to separate and recover the generated chlorine. The chlorine recovery device 90 includes: a mixed gas buffer tank 91, a compressor 92, a liquid chlorine separation tank 93, a second buffer tank 94 and an alkali liquid tank 95, and further includes a balance pressure pipe 96.

[0058] The mixed gas buffer tank 91 is used to receive and store the mixed gas containing chlorine. The mixed gas buffer tank 91 is, for example, a 2000L storage tank. In some embodiments of the present invention, the mixed gas buffer tank 91 includes a tank body 911 and an elliptical head 912 arranged on the top of the tank body 911. The elliptical head 912 includes an inner elliptical head and an outer elliptical head. The outer elliptical head is floatingly arranged outside the inner elliptical head. Hydraulic oil is arranged between the lower edge of the inner elliptical head and the lower edge of the outer elliptical head. Specifically, the outer elliptical head has a certain amount of up and down floating. An appropriate amount of hydraulic oil is injected into the space between the lower edge of the inner elliptical head and the lower edge of the outer elliptical head. The hydraulic oil is, for example, anti-wear hydraulic oil. The above structure enables the mixed gas buffer tank 91 to not only have better sealing properties, but also the hydraulic oil can play a certain cooling and temperature-reducing role on the mixed gas.

[0059] In some embodiments of the present invention, an overflow port (not shown) is provided on the mixed gas buffer tank 91. The overflow port is, for example, provided at the top of the elliptical head 912. The overflow port is connected to an absorption tank (not shown) through a pipeline 100. The alkaline solution in the absorption tank is used to absorb the acidic gas in the mixed gas overflowing from the mixed gas buffer tank 91. When the pressure of the mixed gas in the mixed gas buffer tank 91 reaches a certain value, part of the mixed gas overflows from the overflow port, and the acidic gas therein is absorbed by the alkaline solution in the absorption tank, thereby improving the safety of the mixed gas buffer tank 91. Among them, the alkaline solution tank 95 can be reused as an absorption tank.

[0060] The compressor 92 is connected to the mixed gas buffer tank 91 and the liquid chlorine separation tank 93 respectively through the pipeline 100. The compressor 92 is used to compress the mixed gas discharged from the mixed gas buffer tank 91 to compress the chlorine into liquid and send it to the liquid chlorine separation tank 93 through the pipeline 100. The liquid chlorine separation tank 93 is used to store liquid chlorine. As a preferred embodiment, the compressor 92 is a diaphragm compressor. The mixed gas containing oxygen, argon and chlorine in the mixed gas buffer tank 91 has a certain corrosiveness. Once water vapor penetrates into the mixed gas in the mixed gas buffer tank 91, the corrosiveness of the mixed gas will be greatly enhanced. Therefore, by using a diaphragm compressor with good cylinder sealing to compress the mixed gas, the corrosion resistance of the compressor 92 will be significantly increased. The thickness of the corrosion-resistant metal diaphragm in the diaphragm compressor is preferably 0.3-0.5mm, so as to further improve the corrosion resistance and service life of the compressor 92.

[0061] The chlorine in the mixed gas is compressed into liquid by the compressor 92. The compressor 92 preferably pressurizes the mixed gas to 1.2-1.5 MPa. The chlorine in the mixed gas is compressed into liquid, and other gases in the mixed gas are still in gaseous state. The chlorine compressed into liquid is sent to the liquid chlorine separation tank 93 through the pipeline 100. The liquid chlorine separation tank 93 is provided with a liquid level gauge and a discharge port for discharging liquid chlorine. When the liquid chlorine in the liquid chlorine separation tank 93 reaches a certain amount, the separated liquid chlorine is discharged through the discharge port.

[0062] In some embodiments of the present invention, the chlorine recovery device 90 also includes a balanced pressure pipe 96, and the two ends of the balanced pressure pipe 96 are respectively connected to the pipeline 100 between the mixed gas buffer tank 91 and the compressor 92 and the pipeline 100 between the compressor 92 and the liquid chlorine separation tank 93. Under the compression action of the compressor 92, there is a pressure difference between the gas on the pipeline 100 before and after the compressor 92. By providing the balanced pressure pipe 96, the pressure difference between the gas on the pipeline 100 before and after the compressor 92 can be effectively eliminated.

[0063] The second buffer tank 94 is connected to the liquid chlorine separation tank 93 so that the uncompressed mixed gas flows from the liquid chlorine separation tank 93 to the second buffer tank 94. The second buffer tank 94 is connected to the alkali liquid tank 95 through the pipeline 100 so that the gas discharged from the second buffer tank 94 flows to the alkali liquid tank 95 and absorbs the acidic gas. The alkali liquid tank 95 preferably stores a sodium hydroxide aqueous solution or a potassium hydroxide aqueous solution. The second buffer tank 94 can prevent the liquid in the alkali liquid tank 95 from being sucked back into the liquid chlorine separation tank 93, thereby improving the safety of the device. The alkali liquid in the alkali liquid tank 95 absorbs the residual acidic gas in the uncompressed mixed gas and then discharges it into the atmosphere. After testing, the tail gas discharged into the atmosphere has fully met the national emission standards.

[0064] Reference Fig.10 The embodiment of the present invention also provides a method for preparing amorphous nano-spherical silica, which comprises steps S1 to S3, and further comprises step S0. The above-mentioned preparation method is preferably prepared using the above-mentioned equipment for preparing amorphous nano-spherical silica.

[0065] Step S0: heating liquid silicon tetrachloride in an oil bath to vaporize the liquid silicon tetrachloride, and sending the vaporized silicon tetrachloride into a high-temperature plasma torch.

[0066] The heating temperature of the oil bath is preferably 60-80° C. Step S0 is, for example, performed by Figure 2 The silicon tetrachloride feeding device 10 shown is used to heat liquid silicon tetrachloride.

[0067] Step S1: evacuate the equipment for preparing amorphous nano-spherical silicon dioxide, and send gaseous silicon tetrachloride into a high-temperature plasma torch. The gaseous silicon tetrachloride reacts with oxygen to generate silicon dioxide under the action of the high-temperature plasma torch.

[0068] Specifically, the vacuum unit 80 is turned on to evacuate the room. When the vacuum degree in the synthesis chamber 30 for high temperature reaction reaches 10 3 At about 1000 rpm, the RF plasma generator 20 is started, and the high-temperature plasma torch is maintained in normal operation. At the same time, gaseous silicon tetrachloride is vertically injected into the high-temperature plasma torch to achieve a replacement reaction between silicon tetrachloride and oxygen in the synthesis chamber 30, and at this moment, the amorphous transformation of silicon dioxide is completed, and finally amorphous nano-spherical silicon dioxide particles are obtained. Step S1 is, for example, performed by Figure 3 The radio frequency plasma generator 20 and the synthesis chamber 30 are shown to carry out the reaction.

[0069] Step S2: After the generated silicon dioxide is cooled, micron-sized silicon dioxide powder, quasi-nano-sized silicon dioxide powder and nano-sized silicon dioxide powder are separated in sequence.

[0070] The chlorine gas and nano-scale silicon dioxide produced in the replacement reaction are quickly cooled in the cooling chamber 40, and then separated by a cyclone separator and a bag separator. The silicon dioxide powder of different particle sizes is effectively screened by air extraction system power of the vacuum unit 80, and the micron-scale silicon dioxide powder, quasi-nano-scale silicon dioxide powder and nano-scale silicon dioxide powder are collected and packaged in the first collection chamber 50, the second collection chamber 62 and the third collection chamber 72 respectively.

[0071] Step S2 is, for example, performed by Figure 1 , Figure 4 , Figure 5 The cooling chamber 40, the first collecting chamber 50, the first separator 61, the second collecting chamber 62, the second separator 71 and the third collecting chamber 72 shown cool and separate the generated silicon dioxide.

[0072] Step S3: Separating and recovering the chlorine in the mixed gas after the silicon dioxide is generated.

[0073] Specifically, in step S3, separating and recovering the chlorine in the mixed gas after the silicon dioxide is generated includes: compressing the mixed gas to compress the chlorine in the mixed gas into a liquid, for example, pressurizing the mixed gas to 1.2-1.5 MPa to compress the chlorine in the mixed gas into a liquid, and the uncompressed mixed gas flows to the alkaline aqueous solution, and the alkaline aqueous solution absorbs the acidic gas in the uncompressed mixed gas. Step S3 is, for example, by Figure 6 and Figure 7The chlorine recovery device 90 shown is used to separate and recover the chlorine in the mixed gas after the silicon dioxide is generated. The residual acid gas in the uncompressed mixed gas is absorbed by the alkali liquid and then discharged into the atmosphere. The tail gas discharged into the atmosphere has fully met the national emission standards.

[0074] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, substitute and modify the above embodiments within the scope of the invention without departing from the principles and purpose of the present invention. All such changes should fall within the scope of protection of the claims of the present invention.

Claims

1. A device for preparing amorphous nano-spherical silicon dioxide, characterized in that: include: Silicon tetrachloride feeding device, radio frequency plasma generator, synthesis chamber, cooling chamber, first collecting chamber, first separator, second collecting chamber, second separator, third collecting chamber, vacuum unit and chlorine recovery device; The silicon tetrachloride feeding device is used to provide gaseous silicon tetrachloride, and the silicon tetrachloride feeding device includes: a silicon tetrachloride storage tank, a delivery pump, a first buffer tank and a heating mechanism. The silicon tetrachloride storage tank is used to store liquid silicon tetrachloride. The delivery pump is connected to the silicon tetrachloride storage tank and the first buffer tank respectively through pipelines. The delivery pump is used to deliver the silicon tetrachloride in the silicon tetrachloride storage tank into the first buffer tank. The heating mechanism is used to heat the pipeline between the delivery pump and the first buffer tank to vaporize the liquid silicon tetrachloride in the pipeline, and the gaseous silicon tetrachloride is delivered outward from the first buffer tank; the radio frequency plasma generator is connected to the synthesis chamber to form a high-temperature plasma torch in the synthesis chamber. The gaseous silicon tetrachloride provided by the silicon tetrachloride feeding device is heated in the synthesis chamber under the action of the high-temperature plasma torch. The first collecting chamber is connected to the cooling chamber to receive part of the silicon dioxide; the first separator is connected to the cooling chamber through a pipeline to receive and separate part of the silicon dioxide, the second collecting chamber is connected to the first separator to receive the silicon dioxide separated by the first separator; the second separator is connected to the first separator to receive and separate part of the silicon dioxide, and the third collecting chamber is connected to the second separator to receive the silicon dioxide separated by the second separator; the chlorine recovery device is connected to the second separator through a pipeline to separate and recover the generated chlorine; the vacuum unit is connected to the pipeline between the second separator and the chlorine recovery device to evacuate the equipment for preparing amorphous nano spherical silicon dioxide; The first collecting chamber is disposed below the cooling chamber to collect micron-sized silicon dioxide powder; The first separator is a cyclone separator, and the second collecting chamber is arranged below the first separator to collect quasi-nanoscale silicon dioxide powder; The second separator is a bag separator, and the third collecting chamber is arranged below the second separator to collect nano-scale silicon dioxide powder.

2. The device for preparing amorphous nano-spherical silicon dioxide according to claim 1, characterized in that: The heating mechanism includes a heating oil bath for heating the pipeline between the delivery pump and the first buffer tank.

3. The device for preparing amorphous nano-spherical silicon dioxide according to claim 1, characterized in that: The silicon tetrachloride feeding device also includes a reflux pipeline, the two ends of which are respectively connected to the pipeline between the silicon tetrachloride storage tank and the delivery pump and the pipeline between the delivery pump and the first buffer tank. The reflux pipeline is used to allow the unvaporized silicon tetrachloride in the pipeline between the delivery pump and the first buffer tank to reflux to the pipeline between the silicon tetrachloride storage tank and the delivery pump.

4. The device for preparing amorphous nano-spherical silicon dioxide according to claim 1, characterized in that: The silicon tetrachloride feeding device also includes a desiccant tank for storing acidic desiccant, and the desiccant tank is connected to the top of the inner cavity of the silicon tetrachloride storage tank through a pipeline.

5. The device for preparing amorphous nano-spherical silicon dioxide according to claim 1, characterized in that: The chlorine gas recovery device comprises: a mixed gas buffer tank, a compressor, a liquid chlorine separation tank, a second buffer tank and an alkali solution tank; The mixed gas buffer tank is used to receive and store a mixed gas containing chlorine. The compressor is connected to the mixed gas buffer tank and the liquid chlorine separation tank through pipelines. The compressor is used to compress the mixed gas discharged from the mixed gas buffer tank to compress the chlorine into liquid and send it to the liquid chlorine separation tank through a pipeline. The liquid chlorine separation tank is used to store liquid chlorine. The second buffer tank is connected to the liquid chlorine separation tank so that uncompressed mixed gas flows from the liquid chlorine separation tank to the second buffer tank. The second buffer tank is connected to the alkali liquid tank through a pipeline so that the gas discharged from the second buffer tank flows to the alkali liquid tank and absorbs the acidic gas.

6. The device for preparing amorphous nano-spherical silicon dioxide according to claim 5, characterized in that: The mixed gas buffer tank includes a tank body and an elliptical head arranged on the top of the tank body, the elliptical head includes an inner elliptical head and an outer elliptical head, the outer elliptical head is floatingly arranged outside the inner elliptical head, and hydraulic oil is arranged between the lower edge of the inner elliptical head and the lower edge of the outer elliptical head.

7. The device for preparing amorphous nano-spherical silicon dioxide according to claim 5, characterized in that: The mixed gas buffer tank is provided with an overflow port, and the overflow port is connected to an absorption tank through a pipeline. The alkaline solution in the absorption tank is used to absorb the acidic gas in the mixed gas overflowing from the mixed gas buffer tank.

8. The device for preparing amorphous nano-spherical silicon dioxide according to claim 5, characterized in that: The chlorine recovery device also includes a balance pressure pipe, and two ends of the balance pressure pipe are respectively connected to the pipeline between the mixed gas buffer tank and the compressor and the pipeline between the compressor and the liquid chlorine separation tank.

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