Chlorine trifluoride preparation system and preparation method

Abstract

The invention relates to the technical field of fine chemical engineering, in particular to a chlorine trifluoride preparation system and a preparation method, and aims to solve the problems that raw materials are wasted and the conversion rate and the purity of chlorine trifluoride are reduced in the preparation method. The chlorine trifluoride preparation system provided by the invention comprises a synthesis reactor, a condensing device, a buffer tank, a compressor and a temporary storage container which are connected in sequence, wherein the temporary storage container is connected with the synthesis reactor; fluorine gas and chlorine gas are introduced into the synthesis reactor for reaction, gas obtained after the reaction enters the condensing device for cooling to obtain chlorine trifluoride liquid and intermediate gas, and the intermediate gas sequentially passes through the buffer tank, the compressor and the temporary storage container and then enters the synthesis reactor; the chlorine trifluoride liquid is discharged from the condensing device. According to the invention, F2 and an intermediate product ClF in the intermediate gas are fully utilized, the conversion rate and purity of chlorine trifluoride are improved, and the treatment load of a tail gas system is also reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of fine chemicals, and in particular to a chlorine trifluoride preparation system and a preparation method. Background Art

[0002] Chlorine trifluoride is a colorless corrosive gas or a pale yellow liquid with a liquid density of 1.825 g / cm 3 , melting point -76.34℃, boiling point 11.75℃. Easily soluble in anhydrous hydrogen fluoride, carbon tetrachloride, etc. Chlorine trifluoride is a strong oxidant with high chemical reactivity. It is one of the most active compounds known. It can react explosively with water and organic compounds and is a hazardous chemical. In recent years, with the rapid development of the semiconductor, liquid crystal, solar energy and LED industries, chlorine trifluoride has been widely used in CVD (chemical vapor deposition chamber) cleaning, wafer etching and other process links, and the demand is on the rise. Chlorine trifluoride has become one of the key special gases in the semiconductor industry. In addition, chlorine trifluoride is also used as a fluorinating agent, combustion agent and propellant, high-temperature metal cutting oil, etc.

[0003] In the prior art, the methods for purifying chlorine trifluoride are mainly divided into the following categories:

[0004] 1. Solid metal chloride (NaCl or CaCl2) is used as a raw material to react with fluorine gas to generate chlorine gas and chlorine monofluoride, and chlorine monofluoride further reacts with fluorine gas to generate chlorine trifluoride. The advantage of this method is that the raw materials are easy to obtain, but the disadvantages are that it involves gas-solid reaction, the reactor structure is complex, the raw material conversion rate is low, and the reaction needs to be carried out in two steps, involving two separation and purification processes, and the process operation is complicated.

[0005] 2. Fluorine gas is passed into liquid carbon tetrachloride or silicon tetrachloride to react and generate chlorine gas, and then the fluorine gas and chlorine gas are further reacted to generate chlorine trifluoride. The disadvantage of this method is that the raw materials are not easy to obtain, the reaction needs to be carried out in two steps, involving two reactors for gas-liquid and gas-gas reactions, the process operation is complicated, there are too many impurities in the crude product, which is not conducive to purification and difficult to industrial large-scale production.

[0006] 3. After mixing chlorine, fluorine and diluent gas, pass them into a reactor equipped with a catalyst, and use nickel fluoride as a catalyst to purify chlorine trifluoride at (100-400)°C. The advantage of this method is that the reaction is a one-step catalytic synthesis, but the disadvantage is that the reaction requires the addition of a catalyst and the reaction pressure is relatively high.

[0007] Patent CN104477850B discloses a one-step synthesis method for preparing chlorine trifluoride, wherein chlorine, fluorine and diluent gas are mixed and then introduced into a reactor containing a catalyst, and reacted at 100-400°C to obtain product 1; product 1 is then cooled, liquefied, discharged, and vaporized to obtain a chlorine trifluoride product. The chlorine trifluoride prepared by this method has more impurities and a lower yield, which is not conducive to the subsequent impurity removal process for producing electronic grade chlorine trifluoride.

[0008] In the synthesis tail gas of chlorine trifluoride, there is an excess of unreacted F2 and intermediate product ClF, which are removed by cooling the chlorine trifluoride synthesis gas and removing light impurities to obtain crude chlorine trifluoride. This treatment method wastes F2 and intermediate product ClF, and reduces the conversion rate and purity of chlorine trifluoride. Summary of the invention

[0009] The object of the present invention is to provide a chlorine trifluoride preparation system and preparation method, so as to solve the problems of the existing preparation method wasting raw materials and reducing the conversion rate and purity of chlorine trifluoride.

[0010] In order to solve the above technical problems, the technical solution provided by the present invention is:

[0011] A chlorine trifluoride preparation system comprises a synthesis reactor, a condensing device, a buffer tank, a compressor and a temporary storage container connected in sequence, wherein the temporary storage container is connected to the synthesis reactor;

[0012] Fluorine gas and chlorine gas are introduced into the synthesis reactor for reaction, and the gas obtained after the reaction enters the condensing device for cooling to obtain chlorine trifluoride liquid and intermediate gas, and the intermediate gas enters the synthesis reactor after passing through the buffer tank, the compressor and the temporary storage container in sequence, and the chlorine trifluoride liquid is discharged from the condensing device.

[0013] Furthermore, the chlorine trifluoride preparation system also includes a fluorine gas mass flow controller, a chlorine gas mass flow controller and a circulating gas mass flow controller;

[0014] The fluorine gas mass flow controller and the chlorine gas mass flow controller are connected to the synthesis reactor and are used to control the mass flow rates of fluorine gas and chlorine gas entering the synthesis reactor respectively;

[0015] The circulating gas mass flow controller is arranged between the temporary storage container and the synthesis reactor, and is used to control the mass flow rate of the gas in the temporary storage container passing into the synthesis reactor.

[0016] Furthermore, the chlorine trifluoride preparation system also includes a storage tank, and the chlorine trifluoride liquid discharged from the condensing device enters the storage tank for storage.

[0017] Furthermore, the storage tank comprises a main tank body, and the main tank body comprises a vacuum tank body, a storage tank body and a temperature control tube;

[0018] The storage tank body is installed in the vacuum tank body and forms a vacuum interlayer with the vacuum tank body, and the temperature control tube is arranged in the vacuum interlayer and is wound and installed on the outer wall of the storage tank body;

[0019] A flowing liquid is introduced into the temperature control tube.

[0020] Furthermore, the storage tank also includes a vacuum pump, which is connected to the vacuum interlayer. When the vacuum degree of the vacuum interlayer decreases to a set value, the vacuum pump starts.

[0021] Furthermore, the storage tank further comprises a control assembly, and the control assembly comprises a control box and a slider;

[0022] The outlet of the vacuum pump is connected to the control box, and the slider is arranged in the control box and is slidably connected to the control box;

[0023] The sliding block is provided with an exhaust hole and an exhaust groove. The gas extracted by the vacuum pump enters the control box and passes through the exhaust hole and the exhaust groove in sequence before being discharged from the control box.

[0024] Furthermore, the storage tank also includes a spare tank body, and the control assembly also includes a three-way valve, a connecting rod and a connecting frame;

[0025] The three-way valve is connected to the vacuum interlayer, the storage tank and the vacuum pump respectively, and the outlet of the control box is connected to the spare tank;

[0026] One end of the connecting rod is hinged to the connecting frame, and the other end is hinged to the handle of the three-way valve, and the connecting frame is slidably connected to the control box;

[0027] The gas in the vacuum interlayer sequentially enters the control box through the three-way valve and the vacuum pump to push the slider to move, and then the slider abuts against the inner wall of the control box to block the exhaust groove and connect the exhaust hole with the outlet of the control box; at the same time, the slider pushes the connecting frame to move so that the connecting rod drives the handle of the three-way valve to rotate, so that the storage tank is connected with the vacuum pump;

[0028] At this time, the vacuum pump extracts the gas in the storage tank, and the gas passes through the three-way valve, the vacuum pump, the control box, and the exhaust hole in sequence and then enters the spare tank.

[0029] Furthermore, the control assembly also includes a return spring and a magnet;

[0030] The return spring and the magnet are respectively arranged at both ends of the slider, and the magnet is installed on the control box; the return spring is used to apply a pulling force to the slider to make the slider move away from the magnet; the magnet is used to attract the slider so that the slider abuts against the inner wall of the control box, so that the exhaust groove is closed.

[0031] Furthermore, the control component also includes an auxiliary valve, which is connected to the vacuum interlayer; the connecting frame moves to push the handle of the auxiliary valve to rotate, thereby opening the auxiliary valve.

[0032] Another aspect of the present invention provides a method for preparing chlorine trifluoride, using the above-mentioned chlorine trifluoride preparation system, comprising the following steps:

[0033] The preheated fluorine gas and chlorine gas are respectively introduced into the synthesis reactor, and the gas obtained after the reaction in the synthesis reactor is introduced into the condensation device for cooling to obtain chlorine trifluoride liquid and intermediate gas;

[0034] The chlorine trifluoride liquid is discharged from the condensing device and stored; the intermediate gas passes through the buffer tank and the compressor in sequence and enters the temporary storage container for storage. When the gas pressure in the temporary storage container reaches a set value, the intermediate gas in the temporary storage container is introduced into the synthesis reactor;

[0035] The intermediate gas includes fluorine gas, ClF gas and ClF3 gas.

[0036] Based on the above technical solutions, the technical effects that can be achieved by the present invention are:

[0037] The chlorine trifluoride preparation system provided by the present invention comprises a synthesis reactor, a condensing device, a buffer tank, a compressor and a temporary storage container which are connected in sequence, wherein the temporary storage container is connected to the synthesis reactor; fluorine gas and chlorine gas are introduced into the synthesis reactor for reaction, and the gas obtained after the reaction enters the condensing device for cooling to obtain chlorine trifluoride liquid and intermediate gas, and the intermediate gas enters the synthesis reactor after passing through the buffer tank, the compressor and the temporary storage container in sequence, and the chlorine trifluoride liquid is discharged from the condensing device.

[0038] The chlorine trifluoride preparation system provided by the present invention collects the intermediate gas generated by the synthesis reaction through a buffer tank, transports the intermediate gas to a temporary storage container through a compressor and pressurizes it, and when the intermediate gas in the temporary storage container reaches a set pressure value, the intermediate gas in the temporary storage container returns to the synthesis reactor to realize the recycling of raw materials. This process makes full use of F2 and the intermediate product ClF in the intermediate gas, improves the conversion rate and purity of chlorine trifluoride, and also reduces the processing load of the tail gas system. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0040] Figure 1 A schematic diagram of the structure of a chlorine trifluoride preparation system provided in an embodiment of the present invention;

[0041] Figure 2 It is a structural schematic diagram of a storage tank;

[0042] Figure 3 This is a schematic diagram of the structure of the main tank;

[0043] Figure 4 It is a schematic diagram of the structure of the control component;

[0044] Figure 5 is another structural schematic diagram of the control component;

[0045] Figure 6 is a cross-sectional schematic diagram of a control box;

[0046] Figure 7 A schematic cross-sectional view of a slider.

[0047] Icons: 10, synthesis reactor; 20, condensation device; 30, buffer tank; 40, compressor; 50, temporary storage container; 60, fluorine gas mass flow controller; 70, chlorine gas mass flow controller; 80, circulating gas mass flow controller; 11, pressure gauge; 12, check valve; 13, solenoid valve;

[0048] 100, main tank body; 110, vacuum tank body; 120, storage tank body; 130, temperature control tube; 140, first valve; 150, second valve; 160, discharge pipe; 170, feed pipe; 180, recovery pipe; 190, pressure valve; 101, vacuum interlayer;

[0049] 200. Vacuum pump;

[0050] 300, control assembly; 310, control box; 320, slider; 330, three-way valve; 340, connecting rod; 350, connecting frame; 360, return spring; 370, magnet; 380, auxiliary valve; 321, exhaust hole; 322, exhaust groove. DETAILED DESCRIPTION

[0051] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0052] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0053] Some embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0054] In the synthesis tail gas of chlorine trifluoride, there is an excess of unreacted F2 and intermediate product ClF, which are removed by cooling the chlorine trifluoride synthesis gas and removing light impurities to obtain crude chlorine trifluoride. This treatment method wastes F2 and intermediate product ClF, and reduces the conversion rate and purity of chlorine trifluoride.

[0055] In view of this, the present invention provides a chlorine trifluoride preparation system, comprising a synthesis reactor 10, a condensing device 20, a buffer tank 30, a compressor 40 and a temporary storage container 50 connected in sequence, wherein the temporary storage container 50 is connected to the synthesis reactor 10; fluorine gas and chlorine gas are introduced into the synthesis reactor 10 for reaction, and the gas obtained after the reaction enters the condensing device 20 for cooling to obtain chlorine trifluoride liquid and intermediate gas, and the intermediate gas enters the synthesis reactor 10 after passing through the buffer tank 30, the compressor 40 and the temporary storage container 50 in sequence, and the chlorine trifluoride liquid is discharged from the condensing device 20.

[0056] The chlorine trifluoride preparation system provided by the present invention collects the intermediate gas generated by the synthesis reaction through the buffer tank 30, and conveys the intermediate gas to the temporary storage container 50 through the compressor 40 and pressurizes it. When the intermediate gas in the temporary storage container 50 reaches the set pressure value, the intermediate gas in the temporary storage container 50 returns to the synthesis reactor 10 to realize the recycling of raw materials. This process makes full use of F2 and the intermediate product ClF in the intermediate gas, improves the conversion rate and purity of chlorine trifluoride, and also reduces the processing load of the tail gas system.

[0057] The following combination Figure 1-Figure 7 The structure and shape of the chlorine trifluoride preparation system provided in this embodiment are described in detail:

[0058] In this embodiment, the chlorine trifluoride preparation system further includes a fluorine gas mass flow controller 60, a chlorine gas mass flow controller 70 and a circulating gas mass flow controller 80. Figure 1 As shown, a fluorine gas mass flow controller 60 and a chlorine gas mass flow controller 70 are connected to the synthesis reactor 10, and are used to control the mass flow rates of fluorine gas and chlorine gas entering the synthesis reactor 10 respectively; a circulating gas mass flow controller 80 is arranged between the temporary storage container 50 and the synthesis reactor 10, and is used to control the mass flow rate of the gas in the temporary storage container 50 entering the synthesis reactor 10.

[0059] In this embodiment, the chlorine trifluoride preparation system further includes a pressure gauge 11, a check valve 12 and a solenoid valve 13. The outlet of the synthesis reactor 10, the inlet and outlet of the condensing device 20, the inlet and outlet of the buffer tank 30, and the inlet and outlet of the temporary storage container 50 are all provided with a solenoid valve 13; the synthesis reactor 10, the condensing device 20, the buffer tank 30 and the temporary storage container 50 are all connected with a pressure gauge 11, and the pressure gauge 11 connected to the temporary storage container 50 is linked with the circulating gas mass flow controller 80. When the pressure reaches the set value, the circulating gas mass flow controller 80 is opened to allow the temporary storage container 50 to supply gas to the synthesis reactor 10. A check valve 12 is provided between the condensing device 20 and the buffer tank 30, and a check valve 12 is provided between the temporary storage container 50 and the synthesis reactor 10.

[0060] The chlorine trifluoride preparation system provided in this embodiment also includes a storage tank, and the chlorine trifluoride liquid discharged from the condensing device 20 enters the storage tank for storage. The storage tank includes a main tank body 100, a vacuum pump 200, a control component 300 and a spare tank body such as Figure 2 shown.

[0061] Specifically, the main tank body 100 includes a vacuum tank body 110, a storage tank body 120, a temperature control tube 130, a first valve 140, a second valve 150, a discharge pipe 160, a feed pipe 170, a recovery pipe 180 and a pressure valve 190. Figure 3 As shown. The storage tank 120 is used to store chlorine trifluoride liquid. The storage tank 120 is installed in the vacuum tank 110 and forms a vacuum interlayer 101 with the vacuum tank 110. The temperature control tube 130 is arranged in the vacuum interlayer 101 and is wound and installed on the outer wall of the storage tank 120. The flowing liquid is passed into the temperature control tube 130. The discharge pipe 160, the feed pipe 170 and the recovery pipe 180 are all connected to the storage tank 120 for gas circulation. The discharge pipe 160 is provided with a first valve 140, the feed pipe 170 is provided with a second valve 150, and the recovery pipe 180 is provided with a pressure valve 190.

[0062] In this embodiment, the control assembly 300 includes a control box 310, a slider 320, a three-way valve 330, a connecting rod 340, a connecting frame 350, a return spring 360, a magnet 370 and an auxiliary valve 380. Figure 3 , Figure 4 , Figure 5 , Figure 6 shown.

[0063] The vacuum pump 200 is arranged between the three-way valve 330 and the control box 310. The three-way valve 330 is used to connect the vacuum interlayer 101, the recovery pipe 180 and the vacuum pump 200. The outlet of the control box 310 is connected to the spare tank. The slider 320 is arranged in the control box 310 and is slidably connected to the control box 310; the control box 310 is also provided with an exhaust port, and the slider 320 is provided with an exhaust hole 321 and an exhaust groove 322; one end of the connecting rod 340 is hinged to the connecting frame 350, and the other end is hinged to the handle of the three-way valve 330, and the connecting frame 350 is slidably connected to the control box 310; the return spring 360 and the magnet 370 are respectively arranged at both ends of the slider 320, and the return spring 360 is used to apply a pulling force to the slider 320 to make the slider 320 away from the magnet 370; the magnet 370 is installed on the control box 310, and is used to attract the slider 320 so that the slider 320 abuts against the inner wall of the control box 310 to block the exhaust groove 322; the auxiliary valve 380 is connected to the vacuum interlayer 101. Among them, the exhaust hole 321 is an L-shaped hole, and the connecting frame 350 is a J-shaped structure.

[0064] When the vacuum pump 200 extracts a small amount of gas, the gas enters the control box 310 and passes through the exhaust hole 321 and the exhaust groove 322 in sequence before being discharged from the exhaust port. The pulling force of the return spring 360 can keep the exhaust groove 322 connected to the exhaust port, so as to avoid the vacuum pump 200 repeatedly extracting gas and gradually pushing the slider 320, so that the slider 320 abuts against the inner wall of the control box 310, and then the exhaust groove 322 is blocked. When the vacuum pump 200 extracts more gas, the slider 320 overcomes the pulling force of the return spring 360 and slides under the push of the gas. After the slider 320 moves a certain distance, the magnet 370 attracts the slider 320 to ensure that the slider 320 abuts against the inner wall of the control box 310, thereby completing the blocking of the exhaust groove 322, and at the same time, the exhaust hole 321 is connected to the outlet of the control box 310. At the same time, after the slider 320 moves a certain distance, it can push the connecting frame 350 to move so that the connecting rod 340 swings, and then the connecting rod 340 drives the handle of the three-way valve 330 to rotate, so that the three-way valve 330 switches the connection state, and the storage tank body 120 is connected with the vacuum pump 200. At this time, the vacuum pump 200 extracts the gas in the storage tank body 120, and the gas passes through the three-way valve 330, the vacuum pump 200, the control box 310, and the exhaust hole 321 in turn and then enters the spare tank body.

[0065] As the connecting frame 350 moves, the connecting frame 350 pushes the handle of the auxiliary valve 380 to rotate so that the auxiliary valve 380 is opened. At this time, the gas in the vacuum interlayer 101 can be pumped into the storage container by another vacuum pump to avoid leakage.

[0066] In this embodiment, the working process of the storage tank is as follows:

[0067] The vacuum interlayer 101 provides a vacuum environment to achieve heat preservation; when releasing chlorine trifluoride, a medium at room temperature or a temperature sufficient to convert chlorine trifluoride from liquid to gas flows in the temperature control tube 130, and at this time, the first valve 140 is opened to facilitate the subsequent packaging and use of chlorine trifluoride.

[0068] In the initial state, the three-way valve 330 connects the vacuum interlayer 101 with the vacuum pump 200. A pressure sensor is provided on the pipeline connecting the three-way valve 330 and the vacuum interlayer 101. The pressure sensor is used to monitor the vacuum degree of the vacuum interlayer 101. When the vacuum degree of the vacuum interlayer 101 is reduced to a set value, the vacuum pump 200 is started to extract the gas in the vacuum interlayer 101. The gas passes through the exhaust hole 321 and the exhaust groove 322 in sequence and is discharged from the exhaust port, thereby maintaining the vacuum degree of the vacuum interlayer 101. When the vacuum tank body 110 and the storage tank body 120 are not damaged, the gas extracted by the vacuum pump 200 is small, and the gas is not enough to push the slider 320 a long distance. The slider 320 cannot move to the range of attraction of the magnet. At the same time, the reset spring 360 can reset the slider 320 in time, and the gas is discharged through the exhaust hole 321 and the exhaust groove 322.

[0069] If at least one of the vacuum tank body 110 and the storage tank body 120 is damaged, more gas will enter the vacuum interlayer 101, and the vacuum pump 200 can continuously draw the gas in the vacuum interlayer 101 into the control box 310. Since the amount of gas delivered by the vacuum pump 200 is much larger than the discharge amount of the exhaust groove 322, the gas pushes the slider 320 to move and overcome the pulling force of the return spring 360. Finally, the slider 320 abuts against the inner wall of the control box 310 under the action of the gas push and the attraction of the magnet 370, so that the exhaust groove 322 is blocked and the exhaust hole 321 is connected to the spare tank body. At the same time, the slider 320 pushes the connecting frame 350 to move so that the connecting frame 350 drives the connecting rod 340 to swing, thereby driving the handle of the three-way valve 330 to rotate until the storage tank body 120 is connected to the vacuum pump 200, and the vacuum interlayer 101 is disconnected from the vacuum pump 200. At this time, the vacuum pump 200 generates negative pressure to break through the pressure value of the pressure valve 190, thereby extracting the gas stored in the storage tank body 120, and the gas enters the spare tank body through the exhaust hole 321 to realize the timely transfer of the gas.

[0070] When the connecting frame 350 moves, the connecting frame 350 pushes the handle of the auxiliary valve 380 to rotate so that the auxiliary valve 380 opens, so that another vacuum pump can draw the gas in the vacuum interlayer 101 into the storage container for treatment, so as to avoid chlorine trifluoride entering the vacuum interlayer 101 and being unable to be treated when the storage tank body 120 is damaged.

[0071] In addition, a switch may be provided on the connecting frame 350. When the connecting frame 350 is moved, the temperature of the medium in the temperature control tube 130 may be controlled to increase, thereby accelerating the temperature rise of chlorine trifluoride to increase the transfer speed of the gas.

[0072] Based on the chlorine trifluoride preparation system provided in this embodiment, a chlorine trifluoride preparation method is proposed, which uses the above-mentioned chlorine trifluoride preparation system and includes the following steps:

[0073] The preheated fluorine gas and chlorine gas are respectively introduced into the synthesis reactor 10, and the gas obtained after the reaction in the synthesis reactor 10 is introduced into the condensing device 20 for cooling to obtain chlorine trifluoride liquid and intermediate gas; the chlorine trifluoride liquid is discharged from the condensing device 20 and stored; the intermediate gas passes through the buffer tank 30 and the compressor 40 in sequence and enters the temporary storage container 50 for storage. When the gas pressure in the temporary storage container 50 reaches the set value, the intermediate gas in the temporary storage container 50 is introduced into the synthesis reactor 10; the intermediate gas includes fluorine gas, ClF gas and ClF3 gas.

[0074] Specifically, the preheated raw materials high-purity fluorine gas and high-purity chlorine gas are respectively added to the synthesis reactor 10 through the fluorine gas mass flow controller 60 and the chlorine gas mass flow controller 70. The synthesis gases ClF3, F2, and ClF generated by the reaction in the synthesis reactor 10 are passed through two solenoid valves 13 and introduced into the condensing device 20 to form ClF3 liquid and intermediate gas after cooling. The intermediate gas includes F2 gas, ClF gas, and a small amount of ClF3 gas.

[0075] The uncondensed gas passes through the solenoid valve 13, the check valve 12 and the solenoid valve 13 in sequence and is input into the buffer tank 30 for temporary storage, so as to reduce the impact of subsequent processes on the airflow in the condensing device 20; the compressor 40 pressurizes the gas in the buffer tank 30 and inputs the intermediate gas into the temporary storage container 50; the intermediate gas passes through the solenoid valve 13, the compressor 40 and the solenoid valve 13 in sequence from the buffer tank 30 and enters the temporary storage container 50.

[0076] When the pressure of the intermediate gas accumulated in the temporary storage container 50 reaches 0.4-0.5 MPa, the intermediate gas accumulated in the temporary storage container 50 is supplied as raw material gas to the synthesis reactor 10. The intermediate gas accumulated in the temporary storage container 50 passes through the solenoid valve 13, the check valve 12, the circulating gas mass flow controller 80 and the solenoid valve 13 in sequence and then enters the synthesis reactor 10.

[0077] In this embodiment, the purity of the raw material high-purity fluorine gas is greater than 90%, the purity of the high-purity chlorine gas is greater than 99.9%, and the preheating temperature is 150-200°C.

[0078] In this embodiment, the molar ratio of the raw material high-purity fluorine gas to high-purity chlorine gas is not less than 3:1.

[0079] In this embodiment, the buffer tank 30 mainly plays a role of pressure buffering, forming a material environment with stable pressure before and after the pipeline equipment, and reducing the impact of the subsequent compressor 40 pressurization step on the airflow in the condensing device 20.

[0080] In this embodiment, the condensation temperature of the condensing device 20 is -10°C to -50°C, and the gas pressure at the outlet of the compressor 40 is 0.2 to 0.5 MPa;

[0081] In this embodiment, when the pressure in the temporary storage container 50 reaches 0.4 MPa, the pressure gauge 11 connected to the temporary storage container 50 and the circulating gas mass flow controller 80 are interlocked, and the circulating gas mass flow controller 80 is automatically opened to allow the intermediate gas accumulated in the temporary storage container 50 to enter the synthesis reactor 10 for circulation reaction.

[0082] In actual application, the method for preparing chlorine trifluoride provided in this embodiment is as follows: F2 at 150°C is added to the synthesis reactor 10 at a flow rate of 0.25kg / h, and Cl2 at 150°C is added to the synthesis reactor 10 at a flow rate of 0.10kg / h; the temperature of the synthesis reactor 10 is set to 300°C, the pressure is set to 0.10MPa, and the reaction is carried out for 2h; the temperature of the condensing device 20 is set to -20°C, the chlorine trifluoride synthesis gas is condensed, and liquid chlorine trifluoride is collected by condensation. At the same time, the uncondensed light impurity gas containing the intermediate product is passed to the buffer tank 30. After the pressure of the condensing device 20 is stabilized, the pressure gauge 11 displays 0.03MPa; the temperature of the buffer tank 30 is set to 15°C, which is used to receive the uncondensed gas from the condensing device 20.

[0083] When the pressure of the buffer tank 30 is greater than 0.01 MPa, the compressor 40 is started to pressurize the intermediate gas and transport it to the temporary storage container 50. The outlet pressure of the compressor 40 is 0.2 MPa; when the pressure of the temporary storage container 50 is 0.4 MPa, the circulating gas mass flow controller 80 is automatically opened to control the intermediate gas to be added to the synthesis reactor 10 at a rate of 0.05 kg / h.

[0084] The crude chlorine trifluoride obtained by this operation has a purity of 95.2% and a yield of 92.1%.

[0085] In contrast, the prior art uses nitrogen to purge the system, using fluorine gas with a purity of 98.5% and chlorine gas with a purity of 99.9%, with a molar ratio of fluorine gas to chlorine gas of 3:1, and preheating the fluorine gas to 100°C and the chlorine gas to 100°C respectively; the preheated fluorine gas and chlorine gas enter the mixing chamber of the reactor and mix and then enter the reactor, react at a temperature of 250°C and a pressure of 0MPa (gauge pressure) to obtain a chlorine trifluoride mixed gas. The chlorine trifluoride mixed gas enters the condenser and condenses at -35°C to obtain a condensed liquid, i.e., a crude chlorine trifluoride product; after condensation, non-condensable low-boiling gas impurities, such as ClF, ClO2F, F2 and other gases, are sent to the tail gas purification system through the gas phase outlet pipeline and discharged after purification. The purity of the crude chlorine trifluoride product with most of the low-boiling gas impurities removed is 94.2%, and the yield is 84.6%.

[0086] Compared with the existing technology of directly treating and discharging the light impurity gas after condensation of the synthesis gas, this embodiment recovers and recycles the light impurity gas after condensation of the chlorine trifluoride synthesis gas, including excess fluorine gas, intermediate product ClF, and a small amount of product ClF3, thereby increasing the raw material utilization rate, increasing the conversion rate and yield, and reducing the tail gas treatment load, thereby effectively achieving energy conservation and emission reduction and reducing production costs.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A chlorine trifluoride preparation system, characterized in that: It comprises a synthesis reactor (10), a condensing device (20), a buffer tank (30), a compressor (40) and a temporary storage container (50) which are connected in sequence, and the temporary storage container (50) is connected to the synthesis reactor (10); Fluorine gas and chlorine gas are introduced into the synthesis reactor (10) for reaction, and the gas obtained after the reaction enters the condensing device (20) for cooling to obtain chlorine trifluoride liquid and intermediate gas. The intermediate gas passes through the buffer tank (30), the compressor (40) and the temporary storage container (50) in sequence and then enters the synthesis reactor (10), and the chlorine trifluoride liquid is discharged from the condensing device (20).

2. The chlorine trifluoride preparation system according to claim 1, characterized in that: It also includes a fluorine gas mass flow controller (60), a chlorine gas mass flow controller (70) and a circulating gas mass flow controller (80); The fluorine gas mass flow controller (60) and the chlorine gas mass flow controller (70) are connected to the synthesis reactor (10) and are used to control the mass flow rates of fluorine gas and chlorine gas respectively entering the synthesis reactor (10); The circulating gas mass flow controller (80) is arranged between the temporary storage container (50) and the synthesis reactor (10) and is used to control the mass flow rate of the gas in the temporary storage container (50) passing into the synthesis reactor (10).

3. The chlorine trifluoride preparation system according to claim 1, characterized in that: It also includes a storage tank, in which the chlorine trifluoride liquid discharged from the condensing device (20) enters and is stored.

4. The chlorine trifluoride preparation system according to claim 3, characterized in that: The storage tank comprises a main tank body (100), and the main tank body (100) comprises a vacuum tank body (110), a storage tank body (120) and a temperature control tube (130); The storage tank body (120) is installed in the vacuum tank body (110) and forms a vacuum interlayer (101) with the vacuum tank body (110); the temperature control tube (130) is arranged in the vacuum interlayer (101) and is wound around the outer wall of the storage tank body (120); A flowing liquid is introduced into the temperature control tube (130).

5. The chlorine trifluoride preparation system according to claim 4, characterized in that: The storage tank further comprises a vacuum pump (200), wherein the vacuum pump (200) is in communication with the vacuum interlayer (101), and when the vacuum degree of the vacuum interlayer (101) decreases to a set value, the vacuum pump (200) is started.

6. The chlorine trifluoride preparation system according to claim 5, characterized in that: The storage tank further comprises a control assembly (300), wherein the control assembly (300) comprises a control box (310) and a slider (320); The outlet of the vacuum pump (200) is connected to the control box (310), and the slider (320) is disposed in the control box (310) and is slidably connected to the control box (310); The slider (320) is provided with an exhaust hole (321) and an exhaust groove (322); the gas extracted by the vacuum pump (200) enters the control box (310), passes through the exhaust hole (321) and the exhaust groove (322) in sequence, and is then discharged from the control box (310).

7. The chlorine trifluoride preparation system according to claim 6, characterized in that: The storage tank further comprises a spare tank body, and the control assembly (300) further comprises a three-way valve (330), a connecting rod (340) and a connecting frame (350); The three-way valve (330) is connected to the vacuum interlayer (101), the storage tank (120) and the vacuum pump (200) respectively, and the outlet of the control box (310) is connected to the spare tank; One end of the connecting rod (340) is hinged to the connecting frame (350), and the other end is hinged to the handle of the three-way valve (330); the connecting frame (350) is slidably connected to the control box (310); The gas in the vacuum interlayer (101) enters the control box (310) through the three-way valve (330) and the vacuum pump (200) in sequence to push the slider (320) to move, and then the slider (320) abuts against the inner wall of the control box (310) to block the exhaust groove (322) and connect the exhaust hole (321) with the outlet of the control box (310); at the same time, the slider (320) pushes the connecting frame (350) to move so that the connecting rod (340) drives the handle of the three-way valve (330) to rotate, thereby connecting the storage tank body (120) with the vacuum pump (200); At this time, the vacuum pump (200) extracts the gas in the storage tank (120), and the gas passes through the three-way valve (330), the vacuum pump (200), the control box (310), and the exhaust hole (321) in sequence before entering the spare tank.

8. The chlorine trifluoride preparation system according to claim 7, characterized in that: The control assembly (300) further includes a return spring (360) and a magnet (370); The return spring (360) and the magnet (370) are respectively arranged at two ends of the slider (320), and the magnet (370) is installed on the control box (310); the return spring (360) is used to apply a pulling force to the slider (320) so that the slider (320) is away from the magnet (370); the magnet (370) is used to attract the slider (320) so that the slider (320) abuts against the inner wall of the control box (310), so that the exhaust groove (322) is closed.

9. The chlorine trifluoride preparation system according to claim 8, characterized in that: The control assembly (300) further comprises an auxiliary valve (380), wherein the auxiliary valve (380) is connected to the vacuum interlayer (101); the connecting frame (350) moves to push the handle of the auxiliary valve (380) to rotate, thereby opening the auxiliary valve (380).

10. A method for preparing chlorine trifluoride, characterized in that: The chlorine trifluoride preparation system according to any one of claims 1 to 9 comprises the following steps: The preheated fluorine gas and chlorine gas are respectively introduced into the synthesis reactor (10), and the gas obtained after the reaction in the synthesis reactor (10) is introduced into the condensation device (20) for cooling to obtain chlorine trifluoride liquid and intermediate gas; The chlorine trifluoride liquid is discharged from the condensing device (20) and stored; the intermediate gas passes through the buffer tank (30) and the compressor (40) in sequence and then enters the temporary storage container (50) for storage; when the gas pressure in the temporary storage container (50) reaches a set value, the intermediate gas in the temporary storage container (50) is introduced into the synthesis reactor (10); The intermediate gas includes fluorine gas, ClF gas and ClF3 gas.

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