CN216877921U

CN216877921U - Desublimation crystallization system

Info

Publication number: CN216877921U
Application number: CN202220362435.0U
Authority: CN
Inventors: 彭光辉; 付涛; 魏静玉; 付文兆; 胡锦文; 张乐华; 陈鹏; 魏军; 陈新平
Original assignee: Guangdong Guangda New Energy Technology Co ltd
Current assignee: Guangdong Guangda New Energy Technology Co ltd
Priority date: 2022-02-22
Filing date: 2022-02-22
Publication date: 2022-07-05
Anticipated expiration: 2032-02-22

Abstract

The utility model discloses a desublimation crystallization system.A crystallization device is provided with a material containing cavity and a medium containing cavity, a heat exchange surface is arranged between the medium containing cavity and the material containing cavity, a stirrer is arranged in the material containing cavity, and a scraper blade is arranged on the stirrer and used for scraping solid crystals condensed on the heat exchange surface; the gas source assembly is connected with the material containing cavity, the gas source assembly is provided with a pressure control valve, a condensing medium source assembly is connected with the medium containing cavity, the condensing medium source assembly is used for providing a condensing medium, and the temperature of the condensing medium is lower than the solidifying point of the gas raw material, so that the gas raw material is subjected to sublimation crystallization on the heat exchange surface. The crystals formed on the heat exchange surface are scraped off by the scraper in the frost layer forming period, so that the heat transfer performance between the heat exchange surface and the gas raw material is prevented from being weakened and the crystals cannot be desublimated, the heat exchange between the condensing medium and the gas raw material can be continuously realized through the heat transfer surface, the gas raw material is desublimated and crystallized to generate dry ice, and the method can be applied to industrial production for preparing a large amount of solid crystals.

Description

Desublimation crystallization system

Technical Field

The utility model relates to the field of chemical production, in particular to a desublimation crystallization system.

Background

The dry ice is solid carbon dioxide, absorbs heat at normal temperature and pressure and is desublimated into gaseous carbon dioxide, so that the dry ice is wide in application and is a green pollution-free material.

In the prior art, in order to obtain dry ice, two methods are generally used, one is to liquefy gaseous carbon dioxide under high pressure to form liquid carbon dioxide, then reduce the temperature and pressure of the liquid carbon dioxide to be below the triple point of the carbon dioxide, the liquid carbon dioxide generates gaseous carbon dioxide and solid carbon dioxide along a gas-solid equilibrium line, and the solid carbon dioxide is the prepared dry ice; the other is to directly desublimate gaseous carbon dioxide into dry ice at low temperature and high pressure. Among them, the first method can be widely used in industrial production due to the "joule-thomson effect", in which liquid carbon dioxide is adiabatically expanded in a lower pressure direction through a porous plug (or throttle valve) under high pressure, and in this process, the volume is increased, the pressure is reduced, and thus the temperature is reduced to form dry ice. In the second method, gaseous carbon dioxide is rapidly cooled in a heat exchanger, so that carbon dioxide gas is condensed into dry ice on the surface of the heat exchanger, but the solidified dry ice is easy to adhere to the surface of the heat exchanger, and the heat exchanger cannot continuously manufacture the dry ice, so that the method is generally used for obtaining a small amount of dry ice in experiments.

Therefore, a device for condensing and making dry ice which can be used for industrial continuous production is needed.

SUMMERY OF THE UTILITY MODEL

In order to overcome the technical defects, the utility model provides a desublimation crystallization system.

In order to solve the problems, the utility model is realized according to the following technical scheme:

the utility model provides a desublimation crystallization system, which comprises:

the crystallizer is provided with a material containing cavity and a medium containing cavity, an interlayer is arranged between the medium containing cavity and the material containing cavity, the inner wall of the interlayer forms a heat exchange surface, a stirrer is arranged in the material containing cavity, and a scraper is arranged on the stirrer and used for scraping solid crystals condensed on the heat exchange surface;

the gas source assembly is connected with the material containing cavity and is used for providing gas raw materials; the gas source assembly is provided with a pressure control valve, and the pressure control valve is used for controlling the pressure of the gas raw material to be 0.1-0.36 MPa;

and the condensation medium source assembly is connected with the medium accommodating cavity and is used for providing condensation medium, and the temperature of the condensation medium is lower than the freezing point of the gas raw material, so that the gas raw material is subjected to desublimation and crystallization on the heat exchange surface.

Preferably, the crystallization device is provided with a first feeding port and a second feeding port, and the first feeding port and the second feeding port are respectively connected with the gas source assembly and the condensing medium source assembly;

the first feeding port and the second feeding port are respectively arranged at two ends of the crystallizing device so as to realize countercurrent heat exchange between the gas raw material and the condensing medium.

Preferably, the first feeding port is connected with the air source assembly, the first feeding port is arranged at the upper end of the crystallizing device, the second feeding port is connected with the condensing medium source assembly, and the second feeding port is arranged at the lower end of the crystallizing device.

Preferably, the scraper is a spiral scraper, the stirrer further comprises a rotating shaft, the rotating shaft is movably connected with the scraper, the rotating shaft is connected with a power source, and the power source is used for driving the rotating shaft to rotate;

and sealing devices are arranged at two ends of the rotating shaft and are used for ensuring the air tightness of the material containing cavity.

Preferably, the crystallization device is provided with a first discharge port, the first discharge port is connected with a separation device, and the separation device is used for separating solid crystals and gas raw materials discharged from the first discharge port.

Preferably, the separation device comprises:

the cyclone separator is internally provided with a vortex structure, and the vortex structure is used for separating solid crystals and gas raw materials; the top of the cyclone separator is provided with an exhaust port for discharging non-desublimated gas raw materials;

and the crystal collecting piece is connected with the outlet end of the cyclone separator to collect the discharged solid crystals.

Preferably, a first reflux assembly is arranged between the separation device and the gas source assembly, and the first reflux assembly feeds the gas raw material which is not desublimed into the gas source assembly;

the first backflow component comprises a first air pump and a first backflow pipe, the first air pump is connected with the air outlet, and the first backflow pipe is connected with the air source component.

Preferably, the gas source assembly further comprises:

the gas source is connected with the crystallization device; the pressure control valve is arranged between the gas source and the first flowmeter and is used for controlling the pressure of the gas raw material;

the first flowmeter is arranged between the gas source and the crystallization device and is used for measuring the flow of the gas raw material.

Preferably, the crystallization device is provided with a second discharge port, the second discharge port is used for discharging a condensing medium, and the condensing medium source assembly comprises:

a source of liquefied natural gas for providing liquefied natural gas;

the pressurization valve is connected with a liquefied natural gas source and is used for pressurizing the liquefied natural gas;

a second flow meter provided between the pressurization valve and the crystallization device, the second flow meter being configured to measure a flow rate of the liquefied natural gas;

the second backflow component is arranged between the second discharge port and the second flowmeter and used for collecting gasified natural gas after heat exchange, the second backflow component comprises a second air pump and a second backflow pipe, the second air pump is connected with the second discharge port, and the second backflow pipe is connected with the flowmeter.

the coolant pump is used for providing coolant liquid and is connected with the crystallization device;

and one end of the low-temperature compressor is connected with the second discharge port, the other end of the low-temperature compressor is connected with the secondary refrigerant pump, and the low-temperature compressor is used for collecting the secondary refrigerant gas raw material subjected to heat exchange and compressing the secondary refrigerant gas raw material into secondary refrigerant liquid at low temperature.

Compared with the prior art, the utility model has the beneficial effects that:

1. in the embodiment of the utility model, the gas raw material and the condensing medium are respectively introduced into the material containing cavity and the medium containing cavity of the crystallizing device, so that the solid crystal with higher purity is obtained after the heat exchange between the gas raw material and the condensing medium is finished, and the condensing medium after the heat exchange is not mixed with impurities and can be recycled.

2. In the embodiment of the utility model, the scraper plate is arranged in the material containing cavity, and the scraper plate rotates to scrape off the solid crystals on the heat exchange surface to prevent the crystals from gathering to generate a frost layer compacting period.

3. In the embodiment of the utility model, the carbon dioxide gas in the material containing cavity is changed from irregular movement turbulent flow state to regular annular flow due to the rotation of the scraper, so that the carbon dioxide gas is uniformly distributed in the material containing cavity, the heat exchange between the carbon dioxide gas and a condensing medium is improved, the dry ice crystals are uniformly condensed on the inner wall of the material containing cavity, and the problem that a large amount of dry ice crystals are accumulated at the discharge port of the material containing cavity and the crystals are difficult to form at the upper part of the material containing cavity is solved.

Drawings

Embodiments of the utility model are described in further detail below with reference to the attached drawing figures, wherein:

FIG. 1 is a schematic diagram of the structure of the desublimation crystallization system of the present invention;

FIG. 2 is a schematic diagram of another desublimation crystallization system of the present invention;

FIG. 3 is a schematic view of the structure of the crystallization apparatus of the present invention.

In the figure:

1. a flow meter;

2. a crystallization device; 201. a material containing cavity; 202. a media reservoir; 203. a first feeding port; 204. a first discharge port; 205. A second discharge opening; 206. a second feeding port; 207. a spiral scraper; 208. a rotating shaft; 209. a sealing device;

3. a separation device; 4. a first air pump; 5. a first return pipe; 6. a pressurization valve; 7. a second flow meter; 8. a second air pump; 9. A second return pipe; 10. a cryogenic compressor; 11. a coolant pump.

Detailed Description

The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it will be understood that they are described herein for the purpose of illustration and explanation and not limitation.

Preferred embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While the preferred embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

The term "include" and variations thereof as used herein is meant to be inclusive in an open-ended manner, i.e., "including but not limited to". Unless specifically stated otherwise, the term "or" means "and/or". The term "based on" means "based at least in part on". The terms "one example embodiment" and "one embodiment" mean "at least one example embodiment". The term "another embodiment" means "at least one additional embodiment". The terms "first," "second," and the like may refer to different or the same object. Other explicit and implicit definitions are also possible below.

The dry ice is a solid substance with single component but wide use, the current dry ice manufacturing process temporarily stays at the technical level of 'firstly pressurizing and liquefying, then throttling and cooling', namely firstly preparing liquid carbon dioxide from gaseous carbon dioxide, then cooling and depressurizing the liquid carbon dioxide to below a triple point (-56.6 ℃, 0.52MPa), and generating a gas-solid two phase along a gas-solid equilibrium line to respectively obtain the dry ice and the gaseous carbon dioxide. Another method is to desublimate carbon dioxide to prepare dry ice, and the temperature of the dry ice is required to be below-78.5 ℃ under normal pressure. Theoretically, a low condensing agent with a temperature below-78.5 ℃ is introduced into gaseous carbon dioxide, for example, nitrogen and hydrogen with lower temperatures (both of which are gaseous at-78.5 ℃) can be introduced into gaseous carbon dioxide, but since carbon dioxide releases a large amount of heat during the desublimation process, only a part of carbon dioxide gas can be desublimated into dry ice, and the other part of carbon dioxide gas is mixed into the condensing agent and discharged along with the condensing agent, while the condensing agent with higher purity is usually difficult to obtain, and the condensing agent is usually subjected to repeated pressurization and cooling refrigeration, while the condensing agent mixed with carbon dioxide is difficult to continue cooling refrigeration.

In the process of desublimation of carbon dioxide gas into dry ice crystals, the desublimation process can be roughly divided into three stages: the method comprises a crystal forming period, a frost layer forming period and a frost layer compacting period, wherein the crystal forming period is a plurality of discontinuous dry ice crystals, the frost layer forming period is of a film structure formed by continuously gathering a plurality of dry ice crystals, the frost layer compacting period is further gathered into a dry ice layer with a certain thickness on the basis of the frost layer forming period, and due to the thickness influence of the frost layer compacting period, the sublimation of carbon dioxide reaches dynamic balance in the frost layer compacting period of the conventional dry ice preparation method, the number of the generated dry ice crystals and the number of melted dry ice crystals are equal, and the thickness of the dry ice in the frost layer compacting period is kept unchanged.

In the low-temperature carbon dioxide desublimation complement experiment, dry ice is obtained through a heat exchange tube and a condensing medium, the heat exchange tube is placed in the condensing medium, and carbon dioxide gas is introduced into the heat exchange tube.

The utility model provides a desublimation crystallization system, wherein a gas raw material and a condensing medium are respectively introduced into a material containing cavity 201 and a medium containing cavity 202 of a crystallization device 2, after heat exchange between the gas raw material and the condensing medium is completed, a solid crystal with higher purity is obtained, and impurities are not mixed in the condensing medium after heat exchange, so that the condensing medium can be repeatedly recycled. In addition, because the scraping plate is arranged in the material containing cavity 201, the scraping plate is rotated to scrape solid crystals on the heat exchange surface, and the crystals are prevented from being gathered to generate a frost layer compacting period. And because the scraper blade rotates, the carbon dioxide gas in the material containing cavity 201 is changed from irregular movement turbulent flow state to regular annular flow, so that the carbon dioxide gas is uniformly distributed in the material containing cavity 201, the heat exchange between the carbon dioxide gas and a condensing medium is improved, the dry ice crystals are uniformly condensed on the inner wall of the material containing cavity 201, and the problem that a large amount of dry ice crystals are generated by stacking at the discharge port of the material containing cavity 201 and the upper part of the material containing cavity 201 is difficult to form crystals is solved.

This example will be described in detail with reference to the practical application of carbon dioxide gas to dry ice.

The desublimation crystallization system comprises a crystallization device 2, a gas source assembly and a condensing medium source assembly. The gas source assembly is used for providing carbon dioxide gas, and the condensing medium assembly is used for providing condensing medium.

As shown in the figure, the crystallization device 2 includes a material containing cavity 201 and a medium containing cavity 202, the material containing cavity 201 is a circular hole, the material containing cavity 201 is communicated with a first material inlet 203 and a first material outlet 204, wherein the first material inlet 203 is arranged on the upper left side wall of the crystallization device 2, the first material outlet 204 is arranged on the lower left side wall of the crystallization device 2, the change of the state of the substance of the carbon dioxide from the gaseous state to the gaseous state is met, and the first material inlet 203 is connected with the gas source component through a gas pipe.

Specifically, the air supply subassembly includes the air supply, pressure control valve and first flowmeter 1, the air supply can be for loading carbon dioxide gas's gas holder, or the air supply is for being connected with the valve of carbon dioxide gas supply, first flowmeter 1 locates between air supply and crystallization device 2, first flowmeter 1 is used for measuring carbon dioxide gas's flow, the pressure control valve is used for through the pressure of control carbon dioxide gas, guarantee to carry the pressure that gets into the carbon dioxide gas in crystallization device 2 at 0.1Mpa ~ 0.36Mpa, improve carbon dioxide gas's heat exchange efficiency, prevent carbon dioxide gas liquefaction simultaneously.

The medium containing cavity 202 is an annular interlayer surrounding the material containing cavity 201 and is isolated from the material containing cavity 201, the medium containing cavity 202 is communicated with a second feeding port 206 and a second discharging port 205, the second feeding port 206 is arranged on the right side wall below the crystallizing device 2, the second discharging port 205 is arranged on the right side wall above the crystallizing device 2, the flowing direction of a condensing medium in the medium containing cavity 202 is opposite to the flowing direction of carbon dioxide gas in the material containing cavity 201, the heat transfer temperature difference is improved in a countercurrent heat exchange mode, the heat transfer efficiency of the crystallizing device 2 is improved on the premise that the carbon dioxide gas can be subjected to sublimation crystallization, the sublimation crystallization of the carbon dioxide gas can be completed in a small heat exchange area, the volume of the crystallizing device 2 is saved, and the production cost is reduced.

Specifically, the condensing medium source assembly comprises a liquefied natural gas source, a pressurizing valve 6, a second flowmeter 7 and a second backflow assembly, the liquefied natural gas source is a liquid storage tank loaded with liquefied natural gas, the liquefied natural gas mainly comprises methane, is colorless, odorless, nontoxic and noncorrosive, is liquid natural gas formed after the natural gas is compressed and cooled to-161.5 ℃, and is usually stored in a low-temperature storage tank with the temperature of-161.5 ℃ and the pressure of about 0.1 MPa. The pressure valve 6 is connected with a liquefied natural gas source and used for pressurizing liquefied natural gas, so that the liquefied natural gas has enough pressure to enter the crystallization device 2 from the second feeding port 206, the medium containing cavity 202 is filled with the liquefied natural gas and flows out from the second discharging port 205, a second flowmeter 7 is arranged between the pressure valve 6 and the crystallization device 2, the second flowmeter 7 is used for measuring the flow of the liquefied natural gas, the liquefied natural gas is adjusted through adjusting the flow of the liquefied natural gas, the replacement rate of the liquefied natural gas in the medium containing cavity 202 is adjusted, the temperature of a heat exchange surface can be adjusted, the heat exchange efficiency of the carbon dioxide gas is adjusted, and the purpose of controlling the particle size of the carbon dioxide gas is achieved. The second backflow component is arranged between the second discharge port 205 and the second flowmeter 7, and is used for collecting the gasified natural gas after heat exchange, the natural gas needs to be recovered and conveyed to a natural gas pipeline network after heat exchange, the liquefied natural gas needs to be gasified to be reheated to-20-40 ℃ before being conveyed to the natural gas pipeline network, the liquefied natural gas after heat exchange still contains more cold energy, the liquefied natural gas is directly gasified and conveyed to the natural gas pipeline network, and the cold energy is wasted, so the liquefied natural gas needs to be pressurized again through the second backflow component and conveyed to the crystallization device 2, and the cold energy is fully utilized. The second reflux assembly comprises a second air pump 8 and a second reflux pipe 9, the second air pump 8 is connected with the second discharge port 205, the second reflux pipe 9 is connected with the flowmeter 1, the second air pump 8 pressurizes and liquefies the natural gas with the temperature higher than-161.5 ℃ and lower than-78.5 ℃ after heat exchange, and the natural gas is conveyed to the second feeding port 206 of the crystallization device 2 through the second reflux pipe 9 so as to realize the recycling of the gasified cold energy.

In another embodiment, the condensing media source assembly comprises a coolant pump 11 and a cryogenic compressor 10, the coolant pump 11 is configured to provide a coolant fluid, which may be a modified alkane, and the coolant pump 11 is coupled to the crystallization device 2; one end of the low-temperature compressor 10 is connected with the second discharge port 205, and the other end of the low-temperature compressor 10 is connected with the coolant pump 11, and the low-temperature compressor 10 is used for collecting the heat-exchanged coolant gas raw material and compressing the coolant gas raw material into coolant liquid at a low temperature. The low-temperature compressor 10 pressurizes and liquefies the secondary refrigerant, then the secondary refrigerant is conveyed to the secondary refrigerant pump 11, the secondary refrigerant is conveyed to the crystallization device 2 again through the secondary refrigerant pump 11, recycling of a condensation medium is achieved, the secondary refrigerant after heat exchange is used for increasing pressure and reducing temperature through work of the low-temperature compressor 10 again, circulation is achieved, and the secondary refrigerant pump 11 is enabled to continuously provide secondary refrigerant liquid under the driving of external electric energy.

Be equipped with the agitator in material holds chamber 201, the agitator includes pivot 208, and be fixed in the outer scraper blade of pivot 208, the scraper blade hangs in pivot 208 through the locating pin, pivot 208 is connected with the motor, the motor can drive pivot 208 rotatory, the scraper blade is spiral scraper blade 207, the scraper blade is rotatory along with pivot 208, under the centrifugal force effect of rotatory production, the inseparable material that laminates of scraper blade holds the inner wall in chamber 201, and constantly scrape down the dry ice crystal on the heat-transfer surface in material holds chamber 201 along the direction of rotation, make carbon dioxide gas once more with by being scraped clean heat-transfer surface heat transfer and accomplish the desublimation crystallization, pivot 208 holds chamber 201 concentric setting with the material, effectively guarantee the area of contact of scraper blade and the boundary layer of heat-transfer surface. The spiral scraper 207 enables carbon dioxide gas in the material accommodating cavity 201 to be changed into regular annular flow from an irregular movement turbulent flow state, so that the carbon dioxide gas is uniformly distributed in the material accommodating cavity 201, heat exchange between the carbon dioxide gas and a condensing medium is improved, dry ice crystals are uniformly condensed on the inner wall of the material accommodating cavity 201, and the problem that a large amount of dry ice crystals are generated due to accumulation of a discharge port of the material accommodating cavity 201 and crystallization is difficult to form on the upper portion of the material accommodating cavity 201 is solved.

In another embodiment, the spiral scraper 207 is formed by a plurality of arc-shaped scrapers in a spiral shape, the spiral scraper 207 is connected with the rotating shaft 208 through a spring, and by the characteristics of the spring, when the rotating shaft 208 rotates, the spring is stretched due to the action of centrifugal force, the arc-shaped hanging pieces in the spiral scraper 207 are separated and tightly attached to the inner wall of the material accommodating cavity 201, and dry ice crystals on the heat exchange surface in the material accommodating cavity 201 are continuously scraped along the rotating direction.

In another embodiment, the spiral scraper 207 is eccentrically arranged with the rotating shaft 208, the spiral scraper 207 is connected with the rotating shaft 208 through an elastic connecting piece, the elastic connecting piece is made of diene elastomer foaming material, and the elastic connecting piece can still have good elastic capability at-161.5 ℃. The elastic connecting piece can fill the gap between the spiral scraper blade 207 and the rotating shaft 208, so that the introduced carbon dioxide gas can only pass through the gap between the spiral scraper blade 207 and the inner wall of the material containing cavity 201, the density of the carbon dioxide exchanging heat with the inner wall of the material containing cavity is improved, and further the heat exchange efficiency of the carbon dioxide is improved. Preferably, the downside of spiral scraper blade 207 is equipped with curved elastic separation blade, the tip of spiral scraper blade is located to elastic separation blade, when pivot 208 is rotatory, elastic separation blade can shield the clearance between the inner wall that spiral scraper blade 207 and material hold chamber 201, because elastic separation blade has the arc structure from top to bottom, the carbon dioxide gas that is located the top can flow downwards along the last arcwall face of elastic separation blade, and the carbon dioxide gas that flows into the below is difficult to the backward flow because the effect that blocks of arcwall face is under the elastic separation blade, avoid the carbon dioxide gas that in time exhaust carbon dioxide gas blocks from the entry end entering, prevent that two strands of gas from colliding each other and then cause carbon dioxide gas to become turbulent state once more, avoid reducing the heat exchange efficiency between carbon dioxide gas and the condensing medium.

Specifically, be equipped with sealing device 209 at pivot 208 both ends, sealing device 209 specifically is the bearing seal, guarantees through sealing device 209 that material holds 201 and has good gas tightness, maintains material and holds 201 pressure balance of chamber, the carbon dioxide gas of being convenient for desublimation crystallization. The crystallization device 2 is provided with a safety valve, and the safety valve is used for preventing the pressure in the material containing cavity 201 from exceeding a threshold value so as to automatically release the pressure, thereby ensuring the safety of the production flow.

Preferably, a separation device 3 is arranged below the crystallization device 2, the separation device 3 is connected with the first discharge port 204, the generated dry ice crystals flow to the first discharge port 204 under the action of gravity and the thrust of the carbon dioxide gas without desublimation crystallization, and the separation device 3 is used for separating the dry ice crystals from the carbon dioxide gas. The separation device 3 comprises a cyclone separator and a crystal collecting piece, the crystal collecting piece is arranged at the bottom of the cyclone separator, a generated carbon dioxide gas and dry ice mixture enters the cyclone separator from the side wall of the cyclone separator, the carbon dioxide gas and the dry ice crystals are separated under the action of vortex inside the cyclone separator, the dry ice crystals sink below the cyclone separator and fall onto the crystal collecting piece for collecting the dry ice crystals, and the crystal collecting piece is a collecting net with pores. Be equipped with the gas vent in cyclone's top, the gas vent links to each other with the air supply subassembly, carbon dioxide gas that will not desublimate is inputed crystallization device 2 again through first return assembly in, the utilization ratio of carbon dioxide is improved, first return assembly includes first air pump 4 and first return tube 5, first air pump 4 links to each other with the gas vent, compress the carbon dioxide gas of retrieving to 0.1Mpa ~ 0.36Mpa again, first return tube 5 links to each other with the air supply subassembly, mix the carbon dioxide gas of retrieving with the air supply subassembly output and input to crystallization device 2 in the lump.

Preferably, since the dry ice collected by the separation device 3 is dry ice crystals with small particle size, such dry ice crystals have a large application in the field of dry ice cleaning, and can be rapidly sublimated with heat absorption to improve cleaning efficiency, but block-shaped dry ice with large volume is needed in the refrigeration field, the dry ice crystals can be conveyed into a mold through a conveying device, and a plurality of dry ice crystals are pressed by the mold to be block-shaped dry ice with different shapes.

Other structures of the desublimation crystallization system described in this example are referred to in the prior art.

Although this embodiment describes only a desublimation crystallization system for producing dry ice from carbon dioxide gas, it should be understood that other gases are also within the scope of the present invention if they are used in the same apparatus to obtain crystalline solids from desublimation crystals.

The utility model also provides a desublimation crystallization method, and the desublimation crystallization method is used for the desublimation crystallization system in the embodiment 1.

The following description will be given in detail about the practical application of carbon dioxide gas to dry ice.

During the crystal nucleus formation stage, introducing carbon dioxide gas into the material containing cavity 201 of the crystallization device 2, performing countercurrent heat exchange with a condensing medium in the medium containing cavity 202 through the heat exchange surface, and performing desublimation crystallization to form a crystal nucleus layer and attach the crystal nucleus layer to the surface of the heat exchange surface; the freezing point of the carbon dioxide is-78.5 ℃, the temperature of the condensing medium is below-88.5 ℃, and the pressure in the material cavity 201 is 0.1-0.36 Mpa.

Specifically, let in carbon dioxide gas in the top of crystallization device 2, the condensing medium is let in the below of crystallization device, the carbon dioxide crystallization is arranged from crystallization device 2's below behind the dry ice and falls, the condensing medium flows from up down, countercurrent flow's the heat transfer difference in temperature is compared greatly with the heat transfer difference in heat flow heat transfer, under the prerequisite that the assurance carbon dioxide gas can desublimate the crystallization, the heat transfer efficiency of crystallization device 2 of improvement, the desublimation crystallization of carbon dioxide gas is accomplished to the less heat transfer area of accessible, the volume of crystallization device 2 is saved, and production cost is reduced.

Preferably, the flow rate of the introduced carbon dioxide gas is 0.15m/s to 0.19m/s, the carbon dioxide gas flows in the material accommodating cavity 201 in a turbulent flow state due to the action of the stirrer, the carbon dioxide gas in the turbulent flow state is not easy to exchange heat with a condensing medium, the carbon dioxide is not beneficial to rapid crystallization of the carbon dioxide, the crystallization can be carried out in a long time, and the crystallization position is usually the outlet of the material accommodating cavity 201, namely the bottom of the material accommodating cavity 201. The flowing state of the carbon dioxide gas is adjusted by controlling the flowing speed of the carbon dioxide gas, and the carbon dioxide gas forms regular annular flow by irregular turbulence under the driving of the spiral scraper 207, so that the carbon dioxide gas is uniformly distributed in the material accommodating cavity 201, the heat exchange between the carbon dioxide gas and a condensing medium is improved, the dry ice crystals are uniformly condensed on the inner wall of the material accommodating cavity 201 (namely, a heat exchange surface of the crystallizing device 2), and the problem that a large number of dry ice crystals are generated by stacking at a discharge port of the material accommodating cavity 201 and the crystals are difficult to form on the upper part of the material accommodating cavity 201 is avoided. In addition, by providing sufficient flow of carbon dioxide gas, the carbon dioxide gas which is not desublimated can be ensured to have sufficient flow velocity to drive the dry ice crystals to flow to the discharge opening for discharging.

Preferably, the temperature of the condensing medium is 70-90 ℃ lower than the freezing point of the carbon dioxide gas, namely the temperature of the condensing medium is-168.5-148.5 ℃, at which the carbon dioxide is easy to form fluffy crystals and flocculent crystals, and the fluffy crystals with larger porosity are convenient for scraping by a scraper. The method ensures that the carbon dioxide can quickly finish desublimation crystallization, and simultaneously avoids the carbon dioxide from directly reaching the frost layer densification period in a short time to form a thick dry ice layer.

During the crystal nucleus growth stage, carbon dioxide gas penetrates through the crystal nucleus layer and the heat exchange surface to continue to perform countercurrent heat exchange with the condensing medium, and newly generated crystal nuclei are attached to the surface of the crystal nucleus layer and are gathered to form dry ice crystals.

Specifically, the particle size of the dry ice crystals at the crystal nucleus formation stage is small, the volume is usually less than 100 micrometers, and the dry ice crystals are inconvenient to collect and store, so that gaseous carbon dioxide in the material containing cavity 201 needs to further exchange heat with a heat exchange medium at the crystal nucleus growth stage, a plurality of carbon dioxide crystals are condensed into crystal clusters and enter the frost layer formation stage to form a crystal film, and the particle size of the carbon dioxide at the time can reach 1 mm-3 mm.

When the crystal drops the stage, the scraper blade on the agitator in material appearance chamber 201 rotates and scrapes off the crystal on heat transfer surface to at the regeneration crystal nucleus layer of heat transfer surface, repeated crystal nucleus formation stage and crystal nucleus growth stage.

Specifically, be equipped with rotatory agitator in material holds chamber 201, the agitator comprises pivot 208 and scraper blade, wherein the scraper blade is spiral scraper blade 207, spiral scraper blade 207 makes the carbon dioxide gas in material holds chamber 201 become regular annular flow by the irregular turbulent state of motion, make carbon dioxide gas evenly distributed hold chamber 201 in the material, the heat transfer between carbon dioxide gas and the condensing medium has been improved, make dry ice crystal evenly condense on the inner wall that holds chamber 201 in the material, avoid piling up at the discharge port that holds chamber 201 in the material and produce a large amount of dry ice crystals, and the upper portion that holds chamber 201 in the material is difficult to form the problem of crystallization.

In addition, the rotating speed of the stirrer is r/min, and the residence time of the introduced carbon dioxide gas in the material accommodating cavity 201 is greatly related to the formation of the dry ice crystals, so that the flowing state of the carbon dioxide gas is controlled by controlling the rotating speed of the stirrer, and the residence time of the carbon dioxide gas in the material accommodating cavity 201 is controlled. When the spiral scraper 207 scrapes off the formed dry ice crystals, the dry ice crystals are just in the frost layer formation period, so that the size of the dry ice crystal grains can be controlled conveniently.

Specifically, the pressure in the material cavity 201 is 0.1Mpa to 0.36Mpa, and according to an ideal gas state equation and a density formula, when the temperature in the material cavity 201 is not changed, the pressure in the material cavity 201 is increased, so that the density of the carbon dioxide gas can be increased, and further the heat exchange efficiency of the carbon dioxide gas is improved, but since the pressure of the triple point of the carbon dioxide is 0.52Mpa, theoretically, the liquefaction of the introduced carbon dioxide can be avoided as long as the pressure in the material cavity 201 is controlled within 0.52Mpa, but due to the heat exchange between the material cavity 201 and a condensing medium, the temperature in the material cavity 201 is lower than the temperature of the triple point of the carbon dioxide, so that the liquefaction point of the carbon dioxide is shifted, and the liquefaction is started only at 0.36Mpa, so that the pressure in the material cavity 201 needs to be maintained within 0.36 Mpa. On the other hand, when the pressure in the material cavity 201 is lower than 0.1Mpa, because the pressure difference between the material cavity 201 and the outlet is small, the discharge speed of the carbon dioxide gas which is not crystallized is slow, and further the carbon dioxide gas entering from the inlet end is blocked, and the two gas streams collide with each other, so that the carbon dioxide gas is easily changed into a turbulent flow state again, and the heat exchange efficiency between the carbon dioxide gas and the condensing medium is reduced.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, so that any modification, equivalent change and modification made to the above embodiment according to the technical spirit of the present invention are within the scope of the technical solution of the present invention.

Claims

1. A desublimation crystallization system, comprising:

2. A desublimation crystallization system as claimed in claim 1, wherein:

the crystallization device is provided with a first feeding port and a second feeding port, and the first feeding port and the second feeding port are respectively connected with the gas source assembly and the condensed medium source assembly;

3. A desublimation crystallization system as claimed in claim 2, wherein:

the first feeding port is connected with the air source assembly, the first feeding port is arranged at the upper end of the crystallizing device, the second feeding port is connected with the condensing medium source assembly, and the second feeding port is arranged at the lower end of the crystallizing device.

4. A desublimation crystallization system as claimed in claim 1, wherein:

the scraper is a spiral scraper, the stirrer further comprises a rotating shaft, the rotating shaft is movably connected with the scraper, the rotating shaft is connected with a power source, and the power source is used for driving the rotating shaft to rotate;

5. A desublimation crystallization system as claimed in claim 1, wherein:

the crystallization device is provided with a first discharge port, the first discharge port is connected with a separation device, and the separation device is used for separating solid crystals and gas raw materials discharged from the first discharge port.

6. A desublimation crystallization system of claim 5, wherein the separation device comprises:

7. A desublimation crystallization system of claim 6, wherein:

a first backflow component is arranged between the separation device and the gas source component, and the first backflow component sends the gas raw material which is not desublimated into the gas source component;

8. The desublimation crystallization system of claim 1, wherein the gas source assembly further comprises:

and the first flow meter is arranged between the gas source and the crystallization device and is used for measuring the flow of the gas raw material.

9. The desublimation crystallization system of any one of claims 1 to 8, wherein the crystallization apparatus is provided with a second discharge port for discharging a condensing medium, the condensing medium source assembly comprising:

a source of liquefied natural gas for providing liquefied natural gas;

10. The desublimation crystallization system of any one of claims 1 to 8, wherein the crystallization apparatus is provided with a second discharge port for discharging a condensing medium, the condensing medium source assembly comprising: