Carbon tetrafluoride purification device

Abstract

The utility model discloses a carbon tetrafluoride purification device which comprises a precooler, a low-boiling-point rectifying tower and a high-boiling-point rectifying tower, the precooler comprises a first tower body, a cooling structure communicated with the top of the first tower body and a heat exchanger communicated with the bottom of the first tower body, and the first tower body is provided with an incoming material inlet through which CF4 crude gas enters the precooler; the low-boiling-point rectifying tower is used for separating the CF4 crude gas cooled by the precooler to form a liquid-phase CF4 mixed solution; the high-boiling rectifying tower comprises a second tower body as well as a high-boiling tower cooling assembly and a reboiler which are positioned at the two ends of the second tower body, the second tower body is provided with a high-boiling tower filler section and a high-boiling tower feed port communicated with the high-boiling tower filler section, the high-boiling tower feed port is used for allowing liquid-phase CF4 to enter, the reboiler at the bottom can vaporize CF4 gas in condensed liquid, and the liquid-phase CF4 gas in the condensed liquid enters the high-boiling tower cooling assembly; and high-purity CF4 gas is obtained at the top, heavy-component impurities are obtained at the bottom, and the liquid-phase CF4 can perform heat and mass transfer with the filler section of the high-boiling tower, so that the purification effect of the CF4 is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of carbon tetrafluoride purification, in particular to a carbon tetrafluoride purification device. Background Art

[0002] Carbon tetrafluoride (CF4) is currently the most widely used plasma etching gas in the microelectronics industry. It is widely used in etching thin film materials such as silicon, silicon dioxide, silicon nitride, phosphosilicate glass and tungsten. It is also widely used in electronic device surface cleaning, solar cell production, laser technology, low-temperature refrigeration, gas insulation, leak detection agent, control of space rocket attitude, detergent in printed circuit production, lubricant and brake fluid, etc.

[0003] The microelectronics industry has extremely high requirements for CF4 purity, requiring it to reach electronic grade. Currently, the mainstream CF4 production method in the chemical industry, both domestically and internationally, is the fluorocarbon direct synthesis method, which uses a fluorocarbon reactor to synthesize CF4. The purity of the CF4 produced by this method is primarily limited by the yield of the fluorocarbon reaction stage and the effectiveness of impurity removal during the purification and refining stages. The mixed gas exiting the fluorocarbon reactor contains carbon tetrafluoride, trace amounts of fluorine, hydrogen fluoride, carbon dioxide, carbon monoxide, hexafluoroethane, octafluoropropane, and other gaseous components, requiring crude purification to improve the purity of the CF4.

[0004] Crude carbon tetrafluoride gas is purified using cryogenic distillation technology. The equipment used includes a precooler, a low-boiling distillation tower, and a high-boiling distillation tower. The process flow is divided into the following three steps: ① The crude CF4 gas, which has undergone front-end processes such as dust removal, water washing, alkaline washing, thermal decomposition, and adsorption, is passed into a precooling tank to reduce its temperature (-45°C). ② The precooled crude CF4 gas is passed into the low-boiling distillation tower. The gaseous light impurities such as N2, O2, and CO are discharged from the top of the tower, and the liquid CF4 and heavy impurities are transferred from the bottom of the tower to the high-boiling distillation unit. ③ Once the CF4 enters the high-boiling distillation tower, the liquid heavy impurities such as SF6, C2F6, and C3F8 are discharged from the bottom of the tower and transferred to the fluorocarbon recovery and purification production line. The gaseous CF4 enters the top of the tower, condenses through the condenser, and flows into the product filling station.

[0005] Existing CF4 crude gas pre-cooling is handled by pre-cooling tanks, resulting in poor temperature reduction, which in turn impacts the subsequent low-boiling and high-boiling distillation processes. Furthermore, existing high-boiling CF4 distillation towers are mostly packed distillation units, which are often split-type units with numerous interfaces and piping between devices. This results in high cooling loss during the distillation process, leading to high energy consumption. Furthermore, poor liquid phase distribution in the distillation towers and low packing porosity hinder mass and heat transfer.

[0006] Therefore, how to at least partially solve the above-mentioned drawbacks to improve the purification effect of CF4 is a technical problem that those skilled in the art currently need to solve. Utility Model Content

[0007] The purpose of the utility model is to provide a carbon tetrafluoride purification device, which can avoid the poor effect of temperature reduction in the pre-cooling tank treatment, thereby improving the subsequent CF4 purification effect.

[0008] To achieve the above-mentioned purpose, the present invention provides a carbon tetrafluoride purification device, comprising:

[0009] The precooler includes a first tower body, a cooling structure connected to the top of the first tower body, and a heat exchanger connected to the bottom of the first tower body. The first tower body is provided with an incoming material inlet for the CF4 crude gas to enter the precooler.

[0010] The low-boiling distillation tower is used to remove impurities from the CF4 crude gas cooled by the precooler and then condense and separate it to form liquid CF4;

[0011] The high-boiling distillation tower includes a second tower body and a high-boiling tower cooling assembly and a reboiler located at both ends of the second tower body. The second tower body is provided with a high-boiling tower filling section and a high-boiling tower feed port connected to the high-boiling tower filling section. The high-boiling tower feed port is used for the entry of liquid phase CF4.

[0012] Preferably, the cooling structure includes a first cooling layer and a second cooling layer spaced apart from each other, and the first cooling layer and the second cooling layer are both provided with cooling pipes, a cooling inlet and a cooling outlet connected to the cooling pipes, and the cooling medium circulates between the cooling pipes, the cooling inlet and the cooling outlet to cool the mixed gas in the cooling structure.

[0013] Preferably, the heat exchanger is provided with a heat exchange pipe, which is arranged in a spiral shape. The heat exchange pipe is provided with an inlet and an outlet for the inflow of heat exchange medium. The heat exchange medium circulates in the heat exchange pipe to heat the liquid condensed by the cooling structure and falling into the heat exchanger, so that the CF4-containing part in the condensed liquid is vaporized.

[0014] Preferably, a gas outlet for discharging CF4-containing gas is provided at the top of the cooling structure, and a discharge port is provided at the bottom of the heat exchanger, which is used to discharge the mixed liquid after heat exchange with the heat exchange pipe. The heat exchanger is also provided with a liquid level gauge interface for installing a liquid level gauge, which can detect the liquid level height in the heat exchanger.

[0015] Preferably, the cooling structure and the heat exchanger are both provided with a temperature detection module and a pressure detection module to detect the temperature and pressure in the precooler.

[0016] Preferably, the high boiling tower packing section includes a high boiling tower first-level packing layer, a high boiling tower second-level packing layer, a high boiling tower third-level packing layer and a high boiling tower fourth-level packing layer arranged in sequence, and the high boiling tower first-level packing layer is arranged at the bottom of the second tower body, and the high boiling tower feed inlet is located between the high boiling tower first-level packing layer and the high boiling tower second-level packing layer.

[0017] Preferably, the high boiling tower cooling assembly includes a high boiling tower primary cooling located above the high boiling tower fourth-stage packing layer and a high boiling tower secondary cooling located above the high boiling tower primary cooling. The high boiling tower primary cooling includes a cooling channel for the rising of CF4-containing gas and a spiral pipe surrounding the cooling channel for cooling the gas.

[0018] Preferably, a high boiling tower serpentine tube for gas discharge is provided on the top of the high boiling tower cooling assembly, and the high boiling tower serpentine tube is connected to the high boiling tower finished gas outlet. The high boiling tower cooling assembly is also provided with a tube sheet and a baffle for liquid condensation, and the tube sheet is provided with a pull rod hole for the pull rod to pass through and a through hole for gas to pass through.

[0019] Preferably, the reboiler is provided with a high boiling tower temperature detector for detecting temperature, a high boiling tower pressure detector for detecting pressure, a high boiling tower pressure relief port for discharging pressure, and a high boiling tower drain port located at the bottom of the reboiler for discharging liquid impurities from the reboiler, and the reboiler is a kettle reboiler.

[0020] Preferably, the high boiling distillation tower is an integrated structure.

[0021] Compared with the above-mentioned background technology, the carbon tetrafluoride purification device provided by the present invention includes a precooler, a low-boiling distillation tower and a high-boiling distillation tower. The precooler includes a first tower body, a cooling structure connected to the top of the first tower body, and a heat exchanger connected to the bottom of the first tower body. The first tower body is provided with an incoming material inlet for the CF4 crude gas to enter the precooler; the low-boiling distillation tower is used to remove impurities from the CF4 crude gas cooled by the precooler and condense and separate it to form liquid phase CF4; the high-boiling distillation tower includes a second tower body and a high-boiling tower cooling assembly and a reboiler located at both ends of the second tower body. The second tower body is provided with a high-boiling tower filling section and a high-boiling tower feed port connected to the high-boiling tower filling section. The high-boiling tower feed port is used for the entry of liquid phase CF4.

[0022] Specifically, the CF4 crude gas enters from the feed inlet of the pre-cooling tower, and then the gas ascends and cools the structure in sequence. The CF4 crude gas and the condensed liquid in the cooling structure are in countercurrent contact to conduct gas-liquid two-phase heat transfer, which initially reduces the temperature of the CF4 crude gas. The CF4 crude gas is then further cooled by the cooling structure and discharged from the top of the cooling structure. The cooling of the CF4 crude gas can not only reduce the temperature of the CF4 gas, but also condense and remove gas impurities (critical temperature is within the room temperature range) in the CF4 crude gas, thereby playing a dual role of pre-cooling and pre-purifying the CF4 crude gas. The condensed liquid descends and enters the heat exchanger, where it is partially vaporized after being heated at a low temperature and ascends to the same C After mixing, the F4 crude gas continues to ascend, and the heat exchanger can vaporize the CF4 gas contained in the condensed liquid, reducing the loss rate of CF4 gas during the pre-cooling process, avoiding the poor temperature reduction effect in the pre-cooling tank treatment, and thus improving the subsequent CF4 purification effect. The CF4 crude gas cooled by the pre-cooler is condensed and separated in a low-boiling distillation tower to form liquid CF4, and then transported to a high-boiling distillation tower. By setting the high-boiling tower feed port used for feeding the high-boiling distillation tower in the high-boiling tower packing section, the liquid CF4 can transfer heat and mass with the part of the high-boiling tower packing section located below the high-boiling tower feed port before entering the reboiler, thereby further improving the CF4 purification effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0024] Figure 1 A schematic structural diagram of a precooler provided in an embodiment of the present utility model;

[0025] Figure 2 A schematic structural diagram of a low-boiling distillation tower provided in an embodiment of the present utility model;

[0026] Figure 3 A schematic structural diagram of a high boiling distillation tower provided in an embodiment of the present utility model;

[0027] Figure 4 A schematic diagram of the structure of the tube sheet provided in an embodiment of the present utility model;

[0028] Figure 5 A schematic structural diagram of a baffle provided in an embodiment of the present utility model;

[0029] Figure 6 A schematic diagram of the structure of the high boiling tower serpentine tube provided in an embodiment of the utility model;

[0030] Figure 7 This is a structural schematic diagram of the high boiling tower serpentine tube provided by an embodiment of the present utility model from another perspective.

[0031] in:

[0032] 110 - first tower body, 112 - material inlet, 120 - cooling structure, 121 - first cooling layer, 122 - second cooling layer, 123 - gas outlet, 130 - heat exchanger, 131 - heat exchange pipe, 132 - discharge port, 133 - liquid level gauge interface, 140 - temperature detection module, 150 - pressure detection module;

[0033] 211-high boiling tower packing section, 2111-high boiling tower primary packing layer, 2112-high boiling tower secondary packing layer, 2113-high boiling tower tertiary packing layer, 2114-high boiling tower fourth packing layer, 212-high boiling tower feed port, 220-high boiling tower cooling assembly, 221-high boiling tower primary cooling, 222-high boiling tower secondary cooling, 223-high boiling tower serpentine pipe, 224-high boiling tower finished gas outlet, 225-tube sheet, 226-baffle, 231-high boiling tower temperature detector, 232-high boiling tower pressure detector, 233-high boiling tower pressure relief port, 234-high boiling tower sewage outlet;

[0034] 311- low boiling tower packing section, 3111- low boiling tower first-level packing layer, 3112- low boiling tower second-level packing layer, 3113- low boiling tower third-level packing layer, 312- low boiling tower feed port, 320- low boiling tower cooling assembly, 321- low boiling tower first-level cooling, 322- low boiling tower second-level cooling, 323- low boiling tower serpentine pipe, 324- low boiling tower gas outlet, 331- low boiling tower temperature detector, 332- low boiling tower pressure detector, 333- low boiling tower pressure relief port, 334- low boiling tower sewage outlet. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0036] In order to enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0037] In the description of the present invention, it should be understood that the terms "upper", "lower", "top", "bottom", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the position or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, they cannot be understood as limitations of the present invention.

[0038] The purpose of the utility model is to provide a carbon tetrafluoride purification device, which can avoid the poor effect of temperature reduction in the pre-cooling tank treatment, thereby improving the subsequent CF4 purification effect.

[0039] See also Figure 1 To achieve the above-mentioned purpose, the utility model provides a carbon tetrafluoride purification device, which includes a precooler, a low-boiling distillation tower and a high-boiling distillation tower.

[0040] The precooler includes a first tower body 110, a cooling structure 120 connected to the top of the first tower body 110, and a heat exchanger 130 connected to the bottom of the first tower body 110. The first tower body 110 is provided with an incoming material inlet 112 for the CF4 raw gas to enter the precooler, and the top of the cooling structure 120 is provided with a gas outlet 123 for the discharge of the CF4-containing gas.

[0041] The raw CF4 gas enters the pre-cooling tower from the feed inlet 112 and then ascends through the cooling structure 120. The raw CF4 gas and the condensed liquid passing through the cooling structure 120 come into countercurrent contact to conduct gas-liquid two-phase heat transfer, initially reducing the temperature of the raw CF4 gas. The raw CF4 gas is then further cooled by the cooling structure 120 before being discharged from the top of the cooling structure 120. Cooling the raw CF4 gas not only reduces the temperature of the CF4 gas but also condenses and removes gaseous impurities (whose critical temperature is within the room temperature range) in the raw CF4 gas, thereby achieving the dual functions of pre-cooling and pre-purifying the raw CF4 gas. The condensed liquid descends into the heat exchanger 130, where it is heated at a low temperature and partially vaporized. It then ascends and mixes with the raw CF4 gas before continuing to ascend. The heat exchanger 130 vaporizes the CF4 gas contained in the condensed liquid, reducing the loss rate of CF4 gas during the pre-cooling process, avoiding the poor temperature reduction effect during the pre-cooling tank treatment, and thereby improving the subsequent CF4 purification effect.

[0042] By setting up a pre-cooling tower, the temperature of the CF4 crude gas can be reduced to -30℃~-50℃, effectively sharing the heat load of the low-boiling distillation tower, which is conducive to the stable control of the low-boiling distillation tower. The CF4 distillation unit operates at low temperature. The trace water contained in the crude CF4 gas freezes after entering the pre-cooling tower, and tiny ice crystals remain in the pre-cooling tower. The pre-cooling tower is regularly switched and reheated, and then nitrogen is purged to displace and discharge the ice crystals. This avoids the blockage of the low-boiling distillation tower caused by ice crystals remaining in the low-boiling distillation tower when the pre-cooling tower is not set, thereby ensuring the long-term operation of the CF4 distillation unit.

[0043] See also Figure 2 and Figure 3 The low-boiling distillation tower is used to remove impurities from the CF4 crude gas discharged from the precooler and condense it into a mixed liquid containing CF4; the high-boiling distillation tower includes a second tower body and a high-boiling tower cooling component 220 and a reboiler located at both ends of the second tower body. The high-boiling tower cooling component 220 is located at the top of the second tower body, and the reboiler is located at the bottom of the second tower body. The second tower body is provided with a high-boiling tower packing section 211 and a high-boiling tower feed port 212 connected to the high-boiling tower packing section 211. The high-boiling tower feed port 212 is used for the entry of liquid CF4. The bottom reboiler can vaporize the CF4 gas in the condensed liquid and obtain high-purity CF4 gas at the top and heavy component impurities at the bottom, which are collected and processed regularly.

[0044] It should be noted that the structures of the low-boiling distillation tower and the high-boiling distillation tower are basically the same. The positions of the inlet for the CF4 crude gas discharged from the precooler in the low-boiling distillation tower and the high-boiling tower feed port 212 in the high-boiling distillation tower are different. The low-boiling distillation tower is used to condense and separate the CF4 crude gas into liquid phase CF4, and utilize the different boiling points of the various components in the liquid phase CF4 to remove low-boiling point impurities that are difficult to liquefy in the liquid phase CF4, so as to provide for further separation of the liquid phase CF4 in the subsequent high-boiling distillation tower and further purification of CF4.

[0045] Specifically, the low-boiling distillation tower includes a third tower body and a low-boiling tower cooling assembly 320 and a low-boiling tower reboiler located at both ends of the third tower body. The low-boiling tower cooling assembly 320 is located at the top of the third tower body, and the low-boiling tower reboiler is located at the bottom of the third tower body. The third tower body is provided with a low-boiling tower packing section 311 and a low-boiling tower feed port 312 connected to the low-boiling tower packing section 311. The low-boiling tower feed port 312 is used for the entry of liquid phase CF4.

[0046] It should be noted that the low-boiling tower packing section 311 includes a low-boiling tower primary packing layer 3111, a low-boiling tower secondary packing layer 3112, and a low-boiling tower tertiary packing layer 3113, which are sequentially arranged. The low-boiling tower primary packing layer 3111 is arranged at the bottom of the third tower body, and the low-boiling tower feed inlet 312 is located between the low-boiling tower secondary packing layer 3112 and the low-boiling tower tertiary packing layer 3113. The low-boiling tower cooling assembly 320 includes a low-boiling tower tertiary packing layer 3113 located above the low-boiling tower The low-boiling tower primary cooling system 321 and the low-boiling tower secondary cooling system 322 located above the low-boiling tower primary cooling system 321 are connected. The CF4 crude gas discharged from the precooler enters the low-boiling tower packing section 311 along the low-boiling tower feed port 312. The CF4 crude gas then ascends through the low-boiling tower tertiary packing layer 3113. In this packing layer 3113, the gas and liquid phases undergo countercurrent contact and interphase heat and mass transfer. Volatile components in the liquid phase enter the gas phase, while less volatile components in the gas phase enter the liquid phase. The ascending gas then enters the internal low-boiling tower primary cooling system 321 for cooling. Uncooled gas continues its upward journey and enters the low-boiling tower secondary cooling system 322. Within the low-boiling tower secondary cooling system 322, any gas that needs to be condensed is condensed into a liquid level and flows toward the lower portion of the third tower body. Uncondensed low-boiling point gas is discharged from the top of the system.

[0047] The number of packing layers in the distillation tower is increased to achieve multi-stage liquid phase distribution. The packing material can be Pall rings, etc. The high-porosity packing layer structure is used to increase the specific surface area of ​​the packing layer, thereby improving the mass transfer and heat transfer effects, and greatly improving the distillation effect.

[0048] The low-boiling tower primary cooling 321 includes a cooling channel for gas rising and a spiral pipe surrounding the cooling channel for cooling the gas, and the medium inlet in the spiral pipe is located above the medium outlet. The gas is cooled by the spiral pipe surrounding the cooling channel. The cooling medium of the low-boiling tower primary cooling 321 and the low-boiling tower secondary cooling 322 is preferably liquid nitrogen. In addition, the cooling medium of the low-boiling tower primary cooling 321 and the low-boiling tower secondary cooling 322 can also be selected according to actual conditions as long as the above-mentioned purpose can be achieved.

[0049] A low-boiling tower serpentine tube 323 for gas discharge is provided at the top of the low-boiling tower cooling assembly 320. The axes of the inlet and outlet of the low-boiling tower serpentine tube 323 are consistent with the axis of the third tower body. The low-boiling tower serpentine tube 323 is connected to the low-boiling tower gas outlet 324. A tube sheet 225 and a baffle 226 for liquid condensation are also provided in the low-boiling tower cooling assembly 320. The baffle 226 can promote gas-liquid two-phase heat exchange. The tube sheet 225 is provided with a pull rod hole for the pull rod to pass through and a through hole for gas to pass through.

[0050] The low-boiling tower reboiler is also provided with a low-boiling tower temperature detector 331 for detecting temperature, a low-boiling tower pressure detector 332 for detecting pressure, a low-boiling tower pressure relief port 333 for discharging pressure, and a low-boiling tower sewage port 334 at the bottom of the reboiler for discharging liquid impurities from the reboiler. The low-boiling tower reboiler adopts a kettle-type reboiler, which is convenient for replacement in case of tube failure.

[0051] In this embodiment, the low-boiling distillation tower is an integrated structure, adopting a three-in-one integrated design of the third tower body, the low-boiling tower cooling assembly 320 and the low-boiling tower reboiler, which greatly reduces the number of equipment interfaces and connecting pipes, significantly reduces the loss of cooling capacity, and the integrated equipment saves floor space; it can avoid the disadvantages of the existing low-boiling distillation tower equipment having a large number of interfaces and pipes, easy loss of cooling capacity during the distillation process, and resulting in high energy consumption; at the same time, it can solve the problems of poor liquid phase distribution in the distillation tower, low porosity of the filler, and other phenomena that affect mass transfer and heat transfer.

[0052] The CF4 crude gas discharged from the precooler is converted into a mixed liquid containing CF4 after being removed from the low-boiling distillation tower, and then transported to the high-boiling distillation tower. By setting the high-boiling tower feed inlet 212 used for feeding the high-boiling distillation tower on the high-boiling tower packing section 211, the CF4-containing mixed liquid can transfer heat and mass with the part of the high-boiling tower packing section 211 located below the high-boiling tower feed inlet 212 before entering the reboiler, thereby further improving the purification effect of CF4.

[0053] In this embodiment, the cooling structure 120 includes a first cooling layer 121 and a second cooling layer 122 spaced apart from each other. The first cooling layer 121 and the second cooling layer 122 are both provided with cooling pipes, cooling inlets and cooling outlets connected to the cooling pipes. The cooling pipes can use finned tubes for heat exchange, and the heat exchange areas of the first cooling layer 121 and the second cooling layer 122 are preferably 32 m 2 The cooling medium circulates between the cooling pipe, the cooling inlet and the cooling outlet to cool the mixed gas in the cooling structure 120. The cooling medium is preferably nitrogen. The cooling inlets in the first cooling layer 121 and the second cooling layer 122 are both located below the corresponding cooling outlets. The arrangement of the first cooling layer 121 and the second cooling layer 122 can promote the effect on CF4, and at the same time, can also condense and remove gas impurities (critical temperature is in the room temperature range) in the CF4 raw gas, thereby playing a dual role of pre-cooling and pre-purifying the CF4 raw gas.

[0054] The heat exchanger 130 is provided with a heat exchange pipe 131, which is arranged in a spiral shape. The heat exchange pipe 131 is provided with an inlet and an outlet for the heat exchange medium to flow in. The heat exchange medium circulates in the heat exchange pipe 131 to heat the liquid condensed by the cooling structure 120 and falling into the heat exchanger 130, so as to vaporize the CF4-containing part of the condensed liquid. The heat exchange area of ​​the heat exchanger 130 is preferably 3.7m 2 In order to reduce the loss rate of CF4 gas in the pre-cooling treatment of CF4 crude gas, a discharge port 132 is provided at the bottom of the heat exchanger 130, and the discharge port 132 is used to discharge the mixed liquid that has not been vaporized after heat exchange with the heat exchange pipe 131.

[0055] In one embodiment, the heat exchanger 130 is further provided with a liquid level gauge interface 133 for installing a liquid level gauge, which can detect the liquid level height in the heat exchanger 130. The cooling structure 120 and the heat exchanger 130 are both provided with a temperature detection module 140 and a pressure detection module 150 to detect the temperature and pressure in the precooler. In addition, the first tower body 110 is also provided with a temperature detection module 140.

[0056] It should be noted that the high boiling tower packing section 211 includes a high boiling tower first-level packing layer 2111, a high boiling tower second-level packing layer 2112, a high boiling tower third-level packing layer 2113 and a high boiling tower fourth-level packing layer 2114 that are sequentially arranged at intervals, and the high boiling tower first-level packing layer 2111 is arranged at the bottom of the second tower body, the high boiling tower feed inlet 212 is located between the high boiling tower first-level packing layer 2111 and the high boiling tower second-level packing layer 2112, and the high boiling tower cooling assembly 220 includes a high boiling tower cooling assembly 220 located above the high boiling tower fourth-level packing layer 2114. The high boiling tower primary cooling 221 and the high boiling tower secondary cooling 222 located above the high boiling tower primary cooling 221, the CF4 crude gas discharged from the precooler is converted into liquid CF4 after being removed by the low boiling distillation tower, and enters the high boiling tower primary packing layer 2111 of the high boiling tower packing section 211 along the high boiling tower feed inlet 212, and then falls into the reboiler for heat exchange, and the CF4 and light component impurities in the liquid are vaporized into gas and go up, and the heavy component impurities such as SF6, C2F6, C3F8 in the liquid phase are discharged from the bottom of the reboiler.

[0057] The gas ascends through the high-boiling tower's primary packing layer 2111, where it engages with the incoming liquid through countercurrent flow, undergoing interphase heat and mass transfer. Volatile components in the liquid phase enter the gas phase, while less volatile components in the gas phase transfer to the liquid phase. The gas then ascends sequentially through the high-boiling tower's secondary packing layer 2112, the high-boiling tower's tertiary packing layer 2113, the high-boiling tower's quaternary packing layer 2114, the high-boiling tower's primary cooling system 221, and the high-boiling tower's secondary cooling system 222. From the high-boiling tower's secondary packing layer 2112 to the high-boiling tower's tertiary packing layer 2113, the gas phase undergoes interphase heat transfer with the liquid phase condensed from the high-boiling tower's primary cooling system 221 and the high-boiling tower's secondary cooling system 222. Ultimately, the purified CF4 enters the top of the tower and is collected through the exhaust system at the top.

[0058] The number of packing layers in the distillation tower is increased to achieve multi-stage liquid phase distribution. The packing material can be Pall rings, etc. The high-porosity packing layer structure is used to increase the specific surface area of ​​the packing layer, thereby improving the mass transfer and heat transfer effects, and greatly improving the distillation effect.

[0059] The high boiling tower primary cooling 221 includes a cooling channel for the rising gas containing CF4 and a spiral pipe surrounding the cooling channel for cooling the gas, and the medium inlet in the spiral pipe is located above the medium outlet. The CF4-containing gas is cooled by the spiral pipe surrounding the cooling channel. The cooling medium of the high boiling tower primary cooling 221 and the high boiling tower secondary cooling 222 is preferably liquid nitrogen. In addition, the cooling medium of the high boiling tower primary cooling 221 and the high boiling tower secondary cooling 222 can also be selected according to actual conditions as long as the above-mentioned purpose can be achieved.

[0060] See also Figure 4 、 Figure 5 、 Figure 6 and Figure 7 In this embodiment, a high boiling tower serpentine tube 223 for gas discharge is provided on the top of the high boiling tower cooling component 220. The axes of the inlet and outlet of the high boiling tower serpentine tube 223 are consistent with the axis of the second tower body. The high boiling tower serpentine tube 223 is connected to the high boiling tower finished gas outlet 224. The high boiling tower cooling component 220 is also provided with a tube sheet 225 and a baffle 226 for liquid condensation. The baffle 226 can promote gas-liquid two-phase heat exchange. The tube sheet 225 is provided with a pull rod hole for the pull rod to pass through and a through hole for gas to pass through.

[0061] The reboiler is also provided with a high boiling tower temperature detector 231 for detecting temperature, a high boiling tower pressure detector 232 for detecting pressure, a high boiling tower pressure relief port 233 for discharging pressure, and a high boiling tower sewage port 234 at the bottom of the reboiler for discharging liquid impurities from the reboiler. The reboiler adopts a kettle type reboiler, which is convenient for replacement when the tube fails.

[0062] In this embodiment, the high-boiling distillation tower is an integrated structure, adopting a three-in-one integrated design of the second tower body, the high-boiling tower cooling assembly 220 and the reboiler, which greatly reduces the number of equipment interfaces and connecting pipes, significantly reduces the loss of cooling capacity, and the integrated equipment saves floor space; it can avoid the disadvantages of the existing high-boiling distillation tower equipment having a large number of interfaces and pipes, and the easy loss of cooling capacity during the distillation process, which leads to high energy consumption; at the same time, it can solve the problems of poor liquid phase distribution in the distillation tower, low porosity of the filler, and other phenomena that affect mass transfer and heat transfer.

[0063] It should be noted that, in this specification, relational terms such as first and second are merely used to distinguish one entity from other entities, but do not necessarily require or imply any actual relationship or order between these entities.

[0064] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0065] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from the principles of the present invention, and such improvements and modifications also fall within the scope of protection of the present invention.

Claims

1. A carbon tetrafluoride purification device, characterized in that: include: The precooler comprises a first tower body, a cooling structure connected to the top of the first tower body, and a heat exchanger connected to the bottom of the first tower body, wherein the first tower body is provided with an incoming material inlet for the CF4 crude gas to enter the precooler; A low-boiling distillation tower is used to condense and separate the CF4 crude gas cooled by the precooler to form liquid CF4; The high-boiling distillation tower includes a second tower body and a high-boiling tower cooling assembly and a reboiler located at both ends of the second tower body. The second tower body is provided with a high-boiling tower packing section and a high-boiling tower feed port connected to the high-boiling tower packing section. The high-boiling tower feed port is used for the entry of liquid phase CF4.

2. The carbon tetrafluoride purification device according to claim 1, characterized in that: The cooling structure includes a first cooling layer and a second cooling layer spaced apart from each other. The first cooling layer and the second cooling layer are both provided with a cooling pipe, a cooling inlet and a cooling outlet connected to the cooling pipe. A cooling medium circulates between the cooling pipe, the cooling inlet and the cooling outlet to cool the mixed gas in the cooling structure.

3. The carbon tetrafluoride purification device according to claim 1, characterized in that: The heat exchanger is provided with a heat exchange pipe, which is arranged in a spiral shape. The heat exchange pipe is provided with an inlet and an outlet for the inflow of a heat exchange medium. The heat exchange medium circulates in the heat exchange pipe to heat the liquid condensed by the cooling structure and falling into the heat exchanger, so as to vaporize the CF4-containing portion of the condensed liquid.

4. The carbon tetrafluoride purification device according to claim 3, characterized in that: The top of the cooling structure is provided with a gas outlet for discharging the gas containing CF4, and the bottom of the heat exchanger is provided with a discharge port, which is used to discharge the mixed liquid after heat exchange with the heat exchange pipe. The heat exchanger is also provided with a liquid level gauge interface for installing a liquid level gauge, and the liquid level gauge can detect the liquid level height in the heat exchanger.

5. The carbon tetrafluoride purification device according to claim 1, characterized in that: The cooling structure and the heat exchanger are both provided with a temperature detection module and a pressure detection module to detect the temperature and pressure in the precooler.

6. The carbon tetrafluoride purification device according to claim 1, characterized in that: The high boiling tower packing section includes a high boiling tower first-level packing layer, a high boiling tower second-level packing layer, a high boiling tower third-level packing layer and a high boiling tower fourth-level packing layer which are arranged in sequence, and the high boiling tower first-level packing layer is arranged at the bottom of the second tower body, and the high boiling tower feed port is located between the high boiling tower first-level packing layer and the high boiling tower second-level packing layer.

7. The carbon tetrafluoride purification device according to claim 6, characterized in that: The high boiling tower cooling assembly includes a high boiling tower primary cooling located above the high boiling tower fourth-stage packing layer and a high boiling tower secondary cooling located above the high boiling tower primary cooling. The high boiling tower primary cooling includes a cooling channel for the rising of CF4-containing gas and a spiral pipe surrounding the cooling channel for cooling the gas.

8. The carbon tetrafluoride purification device according to claim 1, characterized in that: A high boiling tower serpentine tube for gas discharge is provided on the top of the high boiling tower cooling component, and the high boiling tower serpentine tube is connected to the high boiling tower finished gas outlet. The high boiling tower cooling component is also provided with a tube plate and a baffle for liquid condensation, and the tube plate is provided with a pull rod hole for the pull rod to pass through and a through hole for gas to pass through.

9. The carbon tetrafluoride purification device according to claim 1, characterized in that: The reboiler is provided with a high boiling tower temperature detector for detecting temperature, a high boiling tower pressure detector for detecting pressure, a high boiling tower pressure relief port for discharging pressure, and a high boiling tower drain port located at the bottom of the reboiler for discharging liquid impurities from the reboiler. The reboiler is a kettle reboiler.

10. The carbon tetrafluoride purification device according to any one of claims 1 to 9, characterized in that: The high boiling distillation tower is an integrated structure.

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