Granular dry ice repressing forming method

Abstract

The invention discloses a granular dry ice repressing forming method which comprises the following steps: screening out dry ice particles with uniform particle size by utilizing an airflow classification technology; fully mixing the magnetic nanoparticles with the dry ice particles by using stirring equipment; performing directional arrangement on the dry ice particles through an external magnetic field, and compacting the dry ice particles into high-density dry ice blocks in combination with a dynamic pressure regulation and control technology; and dry ice blocks obtained after re-pressing forming are conveyed to a low-temperature curing chamber. By means of the pretreatment technology, a uniform micro-thin water film is formed on the surfaces of dry ice particles, the adhesive force between the particles is enhanced, magnetic nano-particles are added, the dry ice particles are directionally arranged through the magnetic field assisted repressing forming technology, the pressure is gradually increased in combination with the dynamic pressure regulation and control technology, and under the combined action of the magnetic field and the pressure, the dry ice particles are subjected to uniform water film forming. The dry ice particles are compacted into high-density dry ice blocks, the dry ice blocks are further solidified and stabilized through a low-temperature solidification technology, the density of the dry ice blocks is improved, and the storage service life of the dry ice blocks is prolonged.

Description

Technical Field

[0001] The present invention relates to the field of dry ice preparation, and specifically to a method for re-pressing granular dry ice into a molded shape. Background Art

[0002] Due to its low temperature characteristics and the feature of no residue after sublimation, dry ice is widely used in fields such as food preservation, medical cold chain, industrial cleaning, and stage special effects. With the increasing demand for dry ice in various industries, higher requirements are put forward for the performance of dry ice, such as density, storage service life, production efficiency, etc. However, traditional dry ice preparation methods have problems such as low density, short storage service life, and high energy consumption, making it difficult to meet the needs of modern industry. Currently, the dry ice preparation methods mainly include compression molding method and particle re-pressing molding method.

[0003] The compression molding method directly forms dry ice blocks by high-pressure compression of liquid carbon dioxide. However, the density of dry ice blocks is relatively low (usually 31.2 mg / cm 3 ), resulting in a short storage service life, high energy consumption, low production efficiency, uneven internal structure of dry ice blocks, and easy generation of cracks.

[0004] The particle re-pressing molding method re-presses dry ice particles into dry ice blocks by mechanical pressure. However, the adhesion force between dry ice particles is insufficient, resulting in a low density of dry ice blocks, uneven particle sizes of dry ice particles, affecting the uniformity and stability of dry ice blocks, lacking optimization of the surface characteristics of dry ice particles, and making it difficult to improve the performance of dry ice blocks. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for re-pressing granular dry ice into a molded shape to solve the problems raised in the above background art.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] A method for re-pressing granular dry ice into a molded shape, comprising the following steps:

[0008] Step S1, transporting dry ice particles to a pretreatment device, forming a uniform thin water film on the surface of the dry ice particles by precisely controlling the temperature and humidity, and using air classification technology to screen out dry ice particles with uniform particle sizes;

[0009] Step S2, transporting the pretreated dry ice particles to a magnetic nanoparticle mixing device, precisely controlling the addition amount of magnetic nanoparticles, and using a stirring device to fully mix the magnetic nanoparticles with the dry ice particles;

[0010] Step S3: Convey the mixed dry ice particles to a magnetic field-assisted recompression molding device. Orient the dry ice particles through an external magnetic field, and in combination with the dynamic pressure regulation technology, gradually increase the pressure. Under the combined action of the magnetic field and pressure, the dry ice particles are compacted into high-density dry ice blocks.

[0011] Step S4: Convey the recompressed dry ice blocks to a low-temperature curing chamber. Further cure and stabilize the dry ice blocks by precisely controlling the temperature and humidity. After the curing is completed, the dry ice blocks are conveyed to the packaging area.

[0012] In the present invention, the particle size uniformity of the dry ice particles is screened by an air classification technology, and the particle size of the screened dry ice particles is controlled within 1 mm to 3 mm.

[0013] In the present invention, the addition amount of the magnetic nanoparticles is 0.1% to 1% of the mass of the dry ice particles, and they are fully mixed with the dry ice particles through a stirring device.

[0014] In the present invention, the intensity of the external magnetic field is 0.1 T to 1 T, and the dry ice particles are oriented through the magnetic field.

[0015] In the present invention, the pressure range of the dynamic pressure regulation technology is 10 MPa to 50 MPa, and the pressure is gradually increased to ensure that the dry ice particles are evenly stressed.

[0016] In the present invention, the temperature of the low-temperature curing chamber is controlled at -80°C to -60°C, and the humidity is controlled at 5% to 10%. The dry ice blocks are further cured and stabilized by precisely controlling the temperature and humidity.

[0017] In the present invention, the magnetic field-assisted recompression molding device includes a magnetic field generator, a pressure regulation device, and a real-time monitoring system. The magnetic field intensity generated by the magnetic field generator is 0.1 T to 1 T, the pressure range of the pressure regulation device is 10 MPa to 50 MPa, and the real-time monitoring system is used to dynamically adjust the magnetic field intensity and pressure parameters.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] 1. Through the pretreatment technology, a uniform thin water film is formed on the surface of the dry ice particles in the present invention to enhance the adhesion between the particles. Magnetic nanoparticles are added, and the magnetic field-assisted recompression molding technology is used to orient the dry ice particles. In combination with the dynamic pressure regulation technology, the pressure is gradually increased. Under the combined action of the magnetic field and pressure, the dry ice particles are compacted into high-density dry ice blocks. Through the low-temperature curing technology, the dry ice blocks are further cured and stabilized, and their density and storage service life are improved.

[0020] 2. Through the pre-treatment technology, the present invention screens out dry ice particles with uniform particle size, provides high-quality raw materials for re-pressing and forming, reduces the energy consumption of subsequent processes, adds magnetic nanoparticles, and uses the magnetic field-assisted re-pressing and forming technology to significantly improve the compaction efficiency of dry ice particles and reduce the energy consumption of pressure regulation. Then, through the low-temperature curing technology, the curing process of dry ice blocks is optimized, and the curing time and energy consumption are reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic flow chart of a method for re-pressing and forming granular dry ice according to the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0023] Please refer to Figure 1 , the present invention provides a technical solution:

[0024] A method for re-pressing and forming granular dry ice, comprising the following steps:

[0025] Step S1, conveying dry ice particles to a pre-treatment device, forming a uniform thin water film on the surface of the dry ice particles by precisely controlling the temperature and humidity, and using air classification technology to screen out dry ice particles with uniform particle size;

[0026] Among them, the particle size uniformity of the dry ice particles is screened by air classification technology, and the particle size of the screened dry ice particles is controlled within 1 mm to 3 mm.

[0027] Specifically, the pre-treatment device includes a temperature control module, a humidity control module, and an air classification module. The initial particle size range of the dry ice particles is 0.5 mm to 6 mm.

[0028] In step S1, the model of the pre-treatment device is CS-Pre-1000. The temperature control module uses a liquid nitrogen cooling system to precisely control the temperature to -70 °C; the humidity control module uses a desiccant and a humidity sensor to precisely control the humidity to 8%; the air classification module uses a cyclone separator to screen out dry ice particles with uniform particle size by adjusting the air flow velocity.

[0029] The technical parameters are as follows:

[0030] Initial particle size range of dry ice particles: 0.5 mm to 6 mm.

[0031] Particle size control range after pretreatment: 1 mm to 3 mm.

[0032] Temperature control: -70 °C.

[0033] Humidity control: 8%.

[0034] The operation process of step S1 is as follows:

[0035] Step S101: Transport dry ice particles to the pretreatment equipment.

[0036] Step S102: Adjust the temperature to -70 °C through the temperature control module and adjust the humidity to 8% through the humidity control module.

[0037] Step S103: Use the air classification module to screen out dry ice particles with uniform particle size, and the particle size after screening is controlled within 1 mm to 3 mm.

[0038] In this embodiment, a uniform thin water film is formed on the surface of the pretreated dry ice particles, enhancing the adhesion between particles. The particle size uniformity of the screened dry ice particles is significantly improved, providing high-quality raw materials for subsequent re-pressing and forming.

[0039] Step S2: Transport the pretreated dry ice particles to the magnetic nanoparticle mixing equipment. By precisely controlling the addition amount of magnetic nanoparticles, use the stirring equipment to fully mix the magnetic nanoparticles with the dry ice particles;

[0040] Among them, the addition amount of the magnetic nanoparticles is 0.1% to 1% of the mass of the dry ice particles, and they are fully mixed with the dry ice particles through the stirring equipment.

[0041] Specifically, the magnetic nanoparticle mixing equipment includes a stirring device and a precise metering module. The particle size of the magnetic nanoparticles is 10 nm to 50 nm, and the magnetization intensity is 50 emu / g.

[0042] In step S2, the model of the magnetic nanoparticle mixing equipment is CS-Mix-2000. The stirring device uses a double-layer spiral stirrer to ensure full mixing of the magnetic nanoparticles and the dry ice particles; the precise metering module uses a high-precision electronic scale to control the addition amount of the magnetic nanoparticles.

[0043] Technical parameters are as follows:

[0044] Addition amount of magnetic nanoparticles: 0.1% to 1% of the mass of the dry ice particles (0.5% is used in the embodiment).

[0045] Particle size of magnetic nanoparticles: 10 nm to 50 nm.

[0046] Magnetization intensity: 50 emu / g.

[0047] Stirring speed: 200 rpm.

[0048] Stirring time: 10 minutes.

[0049] The operation process of step S2 is as follows:

[0050] Step S201: Transport the pretreated dry ice particles to the magnetic nanoparticle mixing device.

[0051] Step S202: Control the addition amount of magnetic nanoparticles through the precise metering module, and the addition amount is 0.5% of the mass of the dry ice particles.

[0052] Step S203: Use the stirring device to fully mix the magnetic nanoparticles and the dry ice particles. The stirring speed is 200 rpm, and the stirring time is 10 minutes.

[0053] In this embodiment, the magnetic nanoparticles are evenly distributed on the surface of the dry ice particles, providing a basis for subsequent magnetic field-assisted re-pressing and forming. The mixed dry ice particles have a high magnetization intensity, which is convenient for magnetic field control.

[0054] The preparation method of the magnetic nanoparticles in the above embodiment is as follows:

[0055] Step S2021: Dissolve iron salt (FeCl3) in deionized water to form an iron salt solution.

[0056] Step S2022: Slowly add a reducing agent (NaBH4) under stirring conditions to react and generate magnetic nanoparticles.

[0057] Step S2023: Add a surfactant (sodium citrate) to stabilize the dispersion of the magnetic nanoparticles.

[0058] Step S2024: Remove the unreacted substances through centrifugal separation and washing.

[0059] Step S2025: Dry the magnetic nanoparticles to obtain magnetic nanoparticles with a particle size of 10 nm to 50 nm.

[0060] Step S3: Transport the mixed dry ice particles to the magnetic field-assisted re-pressing and forming device, and perform directional arrangement on the dry ice particles through an external magnetic field. Combining with the dynamic pressure regulation technology, gradually increase the pressure. Under the combined action of the magnetic field and the pressure, the dry ice particles are compacted into high-density dry ice blocks;

[0061] Among them, the intensity of the external magnetic field is 0.1 T to 1 T, and the dry ice particles are directionally arranged through the magnetic field.

[0062] The pressure range of the dynamic pressure regulation technology is 10 MPa to 50 MPa, and the pressure is gradually increased to ensure that the dry ice particles are evenly stressed.

[0063] The magnetic field-assisted re-pressing forming equipment includes a magnetic field generator, a pressure control device and a real-time monitoring system. The magnetic field intensity generated by the magnetic field generator is 0.1T to 1T, the pressure range of the pressure control device is 10MPa to 50MPa, and the real-time monitoring system is used to dynamically adjust the magnetic field intensity and pressure parameters.

[0064] Specifically, the magnetic field-assisted re-pressing forming equipment includes a magnetic field generator, a pressure control device and a real-time monitoring system. The magnetic field intensity of the magnetic field generator is 0.5T, and the pressure range of the pressure control device is 10MPa to 50MPa.

[0065] In step S3, the model of the magnetic field-assisted re-pressing forming equipment is CS-Press-3000. The magnetic field generator uses a superconducting magnet to generate a uniform magnetic field of 0.1T to 1T; the pressure control device uses a hydraulic system to gradually increase the pressure to 10MPa to 50MPa; the real-time monitoring system uses a pressure sensor and a magnetic field sensor to dynamically adjust the magnetic field intensity and pressure parameters.

[0066] The technical parameters are as follows:

[0067] Magnetic field intensity: 0.1T to 1T.

[0068] Pressure range: 10MPa to 50MPa.

[0069] Dry ice pellet density: 38mg / cm 3 .

[0070] The operation process of step S3 is as follows:

[0071] Step S301, conveying the mixed dry ice pellets into the magnetic field-assisted re-pressing forming equipment.

[0072] Step S302, generating a magnetic field of 0.5T through the magnetic field generator to orient the dry ice pellets.

[0073] Step S303, gradually increasing the pressure in combination with the pressure control device, with the initial pressure being 10MPa and the final pressure being 50MPa.

[0074] Step S304, under the combined action of the magnetic field and pressure, the dry ice pellets are compacted into high-density dry ice blocks.

[0075] In this embodiment, the dry ice pellets form an ordered structure under the action of the magnetic field, significantly improving the uniformity and density of the dry ice blocks. The density of the re-pressed dry ice blocks is 38mg / cm 3 , significantly higher than the density of the dry ice blocks prepared by the traditional method (31.2mg / cm 3 or below).

[0076] Step S4: Transport the recompressed dry ice blocks to the low-temperature curing chamber. By precisely controlling the temperature and humidity, the dry ice blocks are further cured and stabilized. After the curing is completed, the dry ice blocks are transported to the packaging area.

[0077] Among them, the temperature of the low-temperature curing chamber is controlled at -80°C to -60°C, and the humidity is controlled at 5% - 10%. By precisely controlling the temperature and humidity, the dry ice blocks are further cured and stabilized.

[0078] Specifically, the low-temperature curing chamber includes a temperature control module and a humidity control module. The temperature range of the temperature control module is -80°C to -60°C, and the humidity range of the humidity control module is 5% - 10%.

[0079] In step S4, the model of the low-temperature curing chamber is CS-Cure-4000; the temperature control module uses a liquid nitrogen cooling system to precisely control the temperature to -80°C to -60°C; the humidity control module uses desiccants and humidity sensors to precisely control the humidity to 5% - 10%.

[0080] The technical parameters are as follows:

[0081] Temperature control range: -80°C to -60°C.

[0082] Humidity control range: 5% - 10%.

[0083] Curing time: 30 minutes.

[0084] Dry ice block density: 40mg / cm 3 。

[0085] Extended storage service life: 20% - 30%.

[0086] The operation process of step S4 is as follows:

[0087] Step S401: Transport the recompressed dry ice blocks to the low-temperature curing chamber.

[0088] Step S402: Adjust the temperature to -70°C through the temperature control module and adjust the humidity to 8% through the humidity control module.

[0089] Step S403: The curing time is 30 minutes.

[0090] In this embodiment, the dry ice blocks are further cured and stabilized in the low-temperature curing chamber, and the density is increased to 40mg / cm 3 , and the cured dry ice blocks have a relatively high storage service life, extended by 20% - 30%.

[0091] It should be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device.

[0092] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for re-pressing granular dry ice, characterized in that: The following steps are involved: Step S1, conveying dry ice particles to a pretreatment device, forming a uniform thin water film on the surface of the dry ice particles by precisely controlling the temperature and humidity, and screening out dry ice particles with uniform particle size by using airflow classification technology; Step S2, transporting the pretreated dry ice particles to a magnetic nanoparticle mixing device, and fully mixing the magnetic nanoparticles with the dry ice particles by using a stirring device by precisely controlling the amount of magnetic nanoparticles added; Step S3, conveying the mixed dry ice particles to a magnetic field-assisted re-compression molding device, directional arranging the dry ice particles through an external magnetic field, and gradually increasing the pressure in combination with dynamic pressure control technology. Under the combined action of the magnetic field and pressure, the dry ice particles are compacted into high-density dry ice blocks; Step S4, the re-pressed dry ice blocks are transported to a low-temperature solidification chamber, and the dry ice blocks are further solidified and stabilized by precisely controlling the temperature and humidity. After solidification, the dry ice blocks are transported to a packaging area.

2. A granular dry ice re-compression molding method according to claim 1, characterized in that: The particle size uniformity of the dry ice particles is screened by airflow classification technology, and the particle size of the screened dry ice particles is controlled to be 1 mm to 3 mm.

3. The method for re-pressing granular dry ice according to claim 1, characterized in that: The added amount of the magnetic nanoparticles is 0.1% to 1% of the mass of the dry ice particles, and the magnetic nanoparticles are fully mixed with the dry ice particles through a stirring device.

4. The method for re-pressing granular dry ice according to claim 1, characterized in that: The intensity of the external magnetic field is 0.1T to 1T, and the dry ice particles are oriented and arranged by the magnetic field.

5. The method for re-pressing granular dry ice according to claim 1, characterized in that: The dynamic pressure control technology has a pressure range of 10 MPa to 50 MPa, and the dry ice particles are ensured to be evenly stressed by gradually increasing the pressure.

6. The method for re-pressing granular dry ice according to claim 1, characterized in that: The temperature of the low-temperature curing chamber is controlled at -80°C to -60°C, and the humidity is controlled at 5% to 10%. The dry ice blocks are further cured and stabilized by precisely controlling the temperature and humidity.

7. The method for re-pressing granular dry ice according to claim 1, characterized in that: The magnetic field assisted re-pressing forming equipment includes a magnetic field generator, a pressure control device and a real-time monitoring system, wherein the magnetic field intensity generated by the magnetic field generator is 0.1T~1T, the pressure range of the pressure control device is 10MPa~50MPa, and the real-time monitoring system is used to dynamically adjust the magnetic field intensity and pressure parameters.

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