A method for preparing phosphorus trifluoride

Abstract

The invention discloses a preparation method of phosphorus trifluoride, comprising the following steps: S1: adding phosphorus trichloride and anhydrous hydrogen fluoride into a temperature-equalizing material exchange structure of a reactor respectively; S2: condensing crude phosphorus trifluoride gas and passing it into a first storage tank for storage, heating the liquid in the first storage tank and then pumping it into a flash evaporator for flash evaporation; S3: passing the flashed gas into a first distillation tower for rectification, and passing the product into an intermediate first product storage tank; S4: rectifying the material in the intermediate first product storage tank, condensing the rectified gas, and passing it into the first product storage tank for storage; S5: gasifying the finished product in the first product storage tank and passing it into a gas-liquid separation tank for separation, discharging the separated gas from the top and passing it into three phosphorus trifluoride purification devices in sequence for purification; S6: passing the purified gas into a filter for filtration, and after the filtered gas is pressure-stabilized, entering a filling system for filling. The stability of the product and the safety of the equipment are both guaranteed.

Description

Technical Field

[0001] The present invention relates to a production technology of phosphorus trifluoride, in particular to a preparation method of phosphorus trifluoride. Background Art

[0002] Phosphorus trifluoride can be used as a fluorinating agent, which can perform ion transfer and is used in the electronics industry, battery manufacturing, polymer materials and catalysts. In semiconductor manufacturing, phosphorus trifluoride can be converted into plasma gas under the action of microwaves for doping, which can significantly improve semiconductor performance. In the field of polymer materials, phosphorus trifluoride can be used as a reactant to synthesize fluorinated organic dithiophosphates, terephthalate esters and other polymer materials with excellent anti-corrosion properties. In the preparation of phosphorus trifluoride, phosphorus trichloride and anhydrous hydrogen fluoride are mostly used as raw materials for replacement reaction to produce phosphorus trifluoride and hydrogen chloride. The chemical reaction equation is: PCI3+3HF→3HCI+PF3.

[0003] A large amount of heat is generated during the replacement reaction. If phosphorus trichloride and anhydrous hydrogen fluoride are all introduced into the reactor at once, the heat energy generated during the instantaneous reaction can easily cause the temperature to rise rapidly, making it difficult to control the reaction conditions. Therefore, the existing technology uses a microchannel reactor to prepare phosphorus trifluoride, and a dedicated reactor is used to mix the two materials. Although this can achieve the purpose of uniform mixing and rapid heat exchange, it requires the purchase of a dedicated reactor, which can only be used for one purpose, increasing the company's cost investment.

[0004] Therefore, this case aims to provide a method for preparing phosphorus trifluoride, which can directly achieve the effect of a microchannel reactor in a conventional reaction tank, thereby ensuring the stability of the product and the safety of the equipment. Summary of the Invention

[0005] The present invention provides a method for preparing phosphorus trifluoride, which can effectively solve the above problems.

[0006] The present invention is achieved in that:

[0007] A method for preparing phosphorus trifluoride, comprising:

[0008] S1: Phosphorus trichloride and anhydrous hydrogen fluoride are added to the uniform temperature refueling structure of the reactor respectively, and the reaction temperature of the reactor is maintained at 40 to 50°C. The crude phosphorus trifluoride gas after the reaction is discharged along the discharge port of the reactor; the reactor is provided with a feeding seat, and the uniform temperature refueling structure is locked on a sliding cylinder, and the sliding cylinder is slidably connected to the inner wall of the reactor, and the uniform temperature refueling structure comprises a uniform distribution disk movably installed in the reactor, and the uniform distribution disk is communicated with the feeding seat, and a multi-channel reaction structure is connected below the uniform distribution disk, and a multi-stage heat exchange structure is provided on the inner side of the multi-channel reaction structure. A number of heat exchange guide heads are opened on the reactor, and the sliding cylinder rotates after the reactor is loaded, so that the multi-channel reaction structure is docked with the heat exchange guide head, and the phosphorus trichloride and anhydrous hydrogen fluoride are mixed through the feeding seat and the uniform distribution disk and the multi-channel reaction structure and then flow into the reactor;

[0009] S2: condensing the crude phosphorus trifluoride gas and passing it into a first storage tank for storage, then heating the liquid in the first storage tank and pumping it into a flash evaporator for flash evaporation;

[0010] S3: passing the flashed gas into a first distillation tower for rectification, returning the bottom product of the distillation in the first distillation tower, hydrogen fluoride, to the phosphorus trifluoride synthesis process, and condensing the top products of the distillation, phosphorus trifluoride and hydrogen chloride, and passing them into the intermediate first product storage tank;

[0011] S4: Pumping the material in the intermediate first product storage tank into the second distillation tower for rectification, condensing the top gas of the second distillation tower, and refluxing part of the condensed product to the second distillation tower, and passing part to the first product storage tank for storage;

[0012] S5: The finished product in the first product storage tank is pumped into the vaporizer for vaporization. The vaporized gas enters the gas-liquid separation tank for separation. The separated liquid flows back to the vaporizer. The separated gas is discharged from the top and sequentially passed into three phosphorus trifluoride purification equipment for purification.

[0013] S6: The purified gas is filtered into the filter, and the filtered gas enters the second product storage tank. The gas in the second product storage tank is pressurized by the compressor and then enters the buffer tank for pressure-stabilized storage. After pressure stabilization, it enters the filling system for filling.

[0014] As a further improvement, the feeding seat includes a feeding tray arranged inside the reactor, and the top of the feeding tray is provided with a plurality of Y-shaped connectors that pass through the reactor, and the Y-shaped connectors are respectively connected to the input ends of phosphorus trichloride and anhydrous hydrogen fluoride.

[0015] As a further improvement, a barrier pile is provided inside the reactor, several universal guide wheels are provided on the outside of the sliding cylinder, and a convection column is provided at the bottom of the outer side of the sliding cylinder. The convection column is docked with the heat exchange guide head after the sliding cylinder rotates, and the bottom of the sliding cylinder is attached to the barrier pile.

[0016] As a further improvement, the multi-channel reaction structure includes several multi-flow columns connected to the uniformly distributed disk, the length of the multi-flow columns gradually increases from left to right, the multi-flow columns are docked with the outer ring tubes, the outer ring tubes are tightly attached to the inner side of the sliding cylinder and the outer ring tubes are spaced apart, and a downpipe is provided on the side of the multi-flow column away from the uniformly distributed disk.

[0017] As a further improvement, the lower punch tube includes a lower punch head connected to the outer ring tube, a multi-fold tube is connected below the lower punch head, and a laying head is connected to the lower end of the multi-fold tube.

[0018] As a further improvement, adjacent multi-fold tubes are connected by stabilizing bands, and the stabilizing bands on the outermost multi-fold tubes are connected to the inner wall of the sliding cylinder.

[0019] As a further improvement, a corrugated layer is provided on the inner side of the outer ring tube.

[0020] As a further improvement, the multi-stage heat exchange structure includes a transverse accommodating portion tightly attached to the lower end of the uniformly distributed disk, the lower end of the transverse accommodating portion is respectively connected to the transverse embedded portion and the longitudinal embedded portion, the transverse embedded portions are interconnected through bending portions, the transverse embedded portion is embedded in the gap between the outer ring tubes, the longitudinal embedded portion is embedded on the outside of the lower punch tube, and the transverse embedded portion and the longitudinal embedded portion at the bottom are connected to a bottom accommodating portion.

[0021] As a further improvement, a heat flow guide inlet head is provided on the horizontal accommodation portion, and a heat flow guide outlet head is provided on the bottom accommodation portion, and both the heat flow guide inlet head and the heat flow guide outlet head are connected to the heat exchange guide head.

[0022] The beneficial effects of the present invention are:

[0023] In the existing preparation process of phosphorus trifluoride, microchannel reactors are mostly used to delay the reaction process with extremely fast heat exchange, thereby ensuring the stability of the reaction product and the thoroughness of the reaction. Although the purpose of the experiment can be achieved, a dedicated reactor is required. Enterprises need to purchase multiple reactors for different reactions. Therefore, the present invention uses a sliding cylinder to set the uniform temperature material exchange structure to the sliding cylinder, and then adjust the position of the sliding cylinder so that the reaction of phosphorus trifluoride can be completed directly in the uniform temperature material exchange structure. The product is then discharged to the purification stage through the reactor, so that it can be completed directly in the reactor through a replaceable component. When preparing other chemical products, when there is no need to precisely control the reaction conditions, the uniform temperature material exchange structure can be directly removed, allowing the reactor to become an ordinary reactor, thereby directly achieving the effect of one device with multiple uses, and having the functions of normal mixing reaction and microchannel reaction.

[0024] During the installation process of the sliding cylinder, it needs to reach the accurate position, otherwise it will be difficult to achieve the effect of inflow and outflow. Therefore, a universal guide wheel is provided on the outer side of the sliding cylinder of the present invention, which can realize the rotation of the sliding cylinder in the circumferential direction, so that the convection column of the sliding cylinder can form a stable docking with the heat exchange guide head.

[0025] In order to achieve the effect of a microchannel reactor in a uniform temperature material exchange structure, the present invention first sets up a multi-channel reaction structure below the uniform distribution plate, thereby realizing a long-path reaction in a single channel. Not only can the raw materials be poured through multiple channels, but a relatively uniform mixing effect can be achieved in each channel, thereby achieving a uniform and stable reaction effect.

[0026] Since the multi-channel reaction structure has many channels, achieving circulation in multiple channels and requiring longer flow channels between multiple channels are both design pain points. Therefore, the multi-channel reaction structure of the present invention adopts multi-flow columns of different lengths and sets the outer ring tubes at different heights to achieve the dispersion and extension of the flow channels, thereby achieving the effects of diversion and lengthening.

[0027] If the fluid after passing through the extended path of the outer ring tube is directly discharged into the reactor, the distance is still relatively not long enough. Therefore, the present invention sets a lower flushing pipe at the lower end of the outer ring tube, and sets the main path of the lower flushing pipe to a multi-fold pipe. The pipe structure with multiple bends can allow the fluid to form turbulence during flow, thereby improving the mixing effect.

[0028] Although the design of multiple multi-fold tubes improves the mixing effect, multiple thin parallel multi-fold tubes will actually reduce the overall stability and will be relatively unstable when the fluid passes through. Therefore, the multi-fold tubes of this embodiment are connected by stabilizing belts, and the multi-fold tubes are also connected to the sliding cylinder to form a stable multi-section structure.

[0029] Although the multi-channel reaction structure can achieve a long diameter and sufficient reaction effect, due to the long structural path of the multi-channel reaction structure and the variable route path, it is more difficult to exchange heat, so that a lot of heat will accumulate in the reactor. Therefore, the present invention provides a multi-stage heat exchange structure on the basis of the multi-channel reaction structure, which is embedded in the inner side of the multi-channel reaction structure and is in full contact with the multi-channel reaction structure, thereby achieving the effect of rapid heat exchange in multiple parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1 It is a schematic flow diagram of the present invention.

[0032] Figure 2 It is a schematic diagram of the internal structure of the reactor of the present invention.

[0033] Figure 3 It is a structural schematic diagram of the uniform temperature material replacement structure of the present invention.

[0034] Figure 4 It is a structural schematic diagram of the multi-stage heat exchange structure of the present invention.

[0035] Figure 5 It is a structural schematic diagram of the multi-channel reaction structure of the present invention.

[0036] Figure 6 It is a structural schematic diagram of the lower punch pipe of the present invention.

[0037] Figure 7 It is a front view structural schematic diagram of the phosphorus trifluoride purification equipment of the present invention.

[0038] Figure 8 It is a schematic diagram of the top view of the phosphorus trifluoride purification equipment of the present invention.

[0039] Figure 9 It is a schematic diagram of the internal structure of the phosphorus trifluoride purification equipment of the present invention.

[0040] Figure 10 It is a structural schematic diagram of the first molecular sieve adsorption cartridge of the present invention.

[0041] Figure 11 It is a structural schematic diagram of the pressure regulating disk of the present invention.

[0042] Figure 12Schematic diagram of the structure of the inner barrier structure of the present invention.

[0043] Figure 13 It is a structural schematic diagram of the mounting platform of the present invention.

[0044] Figure 14 It is a structural schematic diagram of the parietal bone component of the present invention.

[0045] In the picture:

[0046] Reactor 1, discharge port 101, feeding seat 102, feeding tray 1021, Y-type joint 1022, barrier pile 103, uniform temperature material exchange structure 2, uniform distribution plate 201, multi-channel reaction structure 202, multi-flow column 2021, outer ring tube 2022, lower punch 2023, lower punch 20231, multi-fold tube 20232, layout head 20233, stabilizing belt 20234, pleated layer 20235, multi-stage heat exchange structure 203, horizontal accommodating portion 2031, heat flow guide inlet 20311, heat flow guide outlet 20312, horizontal embedded portion 2032, vertical embedded portion 2033, bending portion 2034, bottom accommodating portion 2035, heat exchange guide head 204, sliding cylinder 3, universal guide wheel 301, convection column 302, adsorption tower body 1 0, guide rail 11, inner groove 12, bearing pocket 13, upper cover 20, air outlet 30, double-position sliding molecular sieve structure 40, first molecular sieve adsorption cylinder 41, material placement frame 411, matching rib groove 412, limiter 413, sealing gasket 4131, locking pin 4132, second molecular sieve adsorption cylinder 42, pressure variable diameter adjustment structure 50, elastic adjustment component 51, first limit spring 511, second limit spring 512, mounting platform 513, C-type ferrule 5131, positioning pin 5132, pressure adjustment disk 52, hole 521, pressure movable disk 522, axial flow channel 523, return flow channel 524, inner barrier structure 53, touch portion 531, barrier portion 532, top bone component 54, extension rod seat 541, separation rod 542. DETAILED DESCRIPTION

[0047] All embodiments of the present invention are within the scope of protection of the present invention. 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 claimed invention, but merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0048] In the description of the present invention, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as referring to the purpose, technical solutions and advantages of the methods. To be 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. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work indicate or imply relative importance or implicitly indicate the number of indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0049] Example 1

[0050] Reference Figures 1 to 6 As shown, a method for preparing phosphorus trifluoride comprises:

[0051] S1: Phosphorus trichloride and anhydrous hydrogen fluoride are added to the temperature-equalizing material exchange structure 2 of the reactor 1 respectively, and the reaction temperature of the reactor 1 is maintained at 40 to 50°C. The crude phosphorus trifluoride gas after the reaction is discharged from the discharge port 101 of the reactor 1; the reactor 1 is provided with a feeding seat 102, the temperature-equalizing material exchange structure 2 is locked on a sliding cylinder 3, and the sliding cylinder 3 is slidably connected to the inner wall of the reactor 1, and the temperature-equalizing material exchange structure 2 includes a uniform distribution plate 201 movably installed in the reactor 1, and the uniform distribution plate 201 is connected to the inner wall of the reactor 1. The feeding seat 102 is connected, and the lower side of the uniform distribution plate 201 is connected to a multi-channel reaction structure 202. A multi-stage heat exchange structure 203 is provided inside the multi-channel reaction structure 202. The reactor 1 is provided with a plurality of heat exchange guides 204. After the reactor 1 is loaded, the sliding cylinder 3 rotates to allow the multi-channel reaction structure 202 to dock with the heat exchange guides 204. The phosphorus trichloride and anhydrous hydrogen fluoride are mixed through the feeding seat 102 and the uniform distribution plate 201 and then flow into the reactor 1.

[0052] S2: condensing the crude phosphorus trifluoride gas and passing it into a first storage tank for storage, then heating the liquid in the first storage tank and pumping it into a flash evaporator for flash evaporation;

[0053] S3: passing the flashed gas into a first distillation tower for rectification, returning the bottom product of the distillation in the first distillation tower, hydrogen fluoride, to the phosphorus trifluoride synthesis process, and condensing the top products of the distillation, phosphorus trifluoride and hydrogen chloride, and passing them into the intermediate first product storage tank;

[0054] S4: Pumping the material in the intermediate first product storage tank into the second distillation tower for rectification, condensing the top gas of the second distillation tower, and refluxing part of the condensed product to the second distillation tower, and passing part to the first product storage tank for storage;

[0055] S5: The finished product in the first product storage tank is pumped into the vaporizer for vaporization. The vaporized gas enters the gas-liquid separation tank for separation. The separated liquid flows back to the vaporizer. The separated gas is discharged from the top and sequentially passed into three phosphorus trifluoride purification equipment for purification.

[0056] S6: The purified gas is filtered into the filter, and the filtered gas enters the second product storage tank. The gas in the second product storage tank is pressurized by the compressor and then enters the buffer tank for pressure-stabilized storage. After pressure stabilization, it enters the filling system for filling.

[0057] During feeding, in order to facilitate the separation and mixing of the materials after feeding, the feeding base 102 includes a feeding tray 1021 arranged inside the reactor 1. The top of the feeding tray 1021 is provided with a plurality of Y-shaped connectors 1022 that penetrate the reactor 1. The Y-shaped connectors 1022 are respectively connected to the input ends of phosphorus trichloride and anhydrous hydrogen fluoride, thereby enabling multi-stage feeding.

[0058] In the existing preparation process of phosphorus trifluoride, microchannel reactors are mostly used to delay the reaction process with extremely fast heat exchange, thereby ensuring the stability of the reaction product and the thoroughness of the reaction. Although the purpose of the experiment can be achieved, a dedicated reactor is required. Enterprises need to purchase multiple reactors for different reactions. Therefore, in this embodiment, the sliding cylinder 3 is slidably set, and the uniform temperature material exchange structure 2 is set to the sliding cylinder 3, and then the position of the sliding cylinder 3 is adjusted so that the reaction of phosphorus trifluoride can be directly completed in the uniform temperature material exchange structure 2. The product is then discharged to the purification stage through the reactor 1, so that it can be directly completed in the reactor 1 through a replaceable component. When preparing other chemical products, when there is no need to precisely control the reaction conditions, the uniform temperature material exchange structure 2 can be directly removed, so that the reactor 1 becomes an ordinary reactor, thereby directly achieving the effect of one device for multiple uses, and at the same time having the functions of normal mixing reaction and microchannel reaction.

[0059] During the installation process of the sliding cylinder 3, it needs to reach the accurate position, otherwise it is difficult to achieve the effect of inflow and outflow. Therefore, a blocking pile 103 is provided inside the reactor 1 of this embodiment, and a number of universal guide wheels 301 are provided on the outside of the sliding cylinder 3. A convection column 302 is provided at the bottom of the outer side of the sliding cylinder 3. The convection column 302 is docked with the heat exchange guide head 204 after the sliding cylinder 3 rotates. The bottom of the sliding cylinder 3 is attached to the blocking pile 103, and a universal guide wheel 301 is provided on the outside of the sliding cylinder 3, which can realize the rotation of the sliding cylinder 3 in the circumferential direction, so that the convection column 302 of the sliding cylinder 3 can form a stable docking with the heat exchange guide head 204.

[0060] In order to achieve the effect of a microchannel reactor in the uniform temperature material exchange structure 2, this embodiment first sets a multi-channel reaction structure 202 below the uniform distribution plate 201, so as to realize a long-path reaction in a single channel. Not only can the raw materials be poured through multiple channels, but also a relatively uniform mixing effect can be achieved in each channel, thereby achieving a uniform and stable reaction effect.

[0061] Since the multi-channel reaction structure 202 has many channels, achieving circulation in multiple channels and requiring longer flow channels between multiple channels are both design pain points. Therefore, the multi-channel reaction structure 202 of this embodiment includes several multi-flow columns 2021 connected to the uniformly distributed disk 201. The length of the multi-flow columns 2021 gradually increases from left to right. The multi-flow columns 2021 are docked with the outer ring tube 2022, and the outer ring tube 2022 is tightly attached to the inner side of the sliding cylinder 3 and the outer ring tubes 2022 are spaced apart. A downpipe 2023 is provided on the side of the multi-flow column 2021 away from the uniformly distributed disk 201. The multi-channel reaction structure 202 adopts multi-flow columns 2021 of different lengths, and the outer ring tube 2022 is set at different heights, so as to achieve the dispersion of the flow channels and the extension of the flow channels, thereby achieving the effects of diversion and lengthening.

[0062] After the fluid has extended its path through the outer ring tube 2022, if it is discharged directly into the reactor 1, the distance is still relatively not long enough. Therefore, the lower punch 2023 of this embodiment includes a lower punch head 20231 connected to the outer ring tube 2022, and a multi-fold tube 20232 is connected to the bottom of the lower punch head 20231. The lower end of the multi-fold tube 20232 is connected to a laying head 20233. By arranging the lower punch 2023 at the lower end of the outer ring tube 2022 and setting the main path of the lower punch 2023 to the multi-fold tube 20232, the multiple bent pipe structures can allow the fluid to form turbulence during flow, thereby improving the mixing effect.

[0063] Although the design of multiple multi-fold tubes 20232 improves the mixing effect, multiple thin parallel multi-fold tubes 20232 will actually reduce the overall stability and will be relatively unstable when the fluid passes through. Therefore, the adjacent multi-fold tubes 20232 in this embodiment are connected by a stabilizing band 20234, and the stabilizing band 20234 on the outermost multi-fold tube 20232 is connected to the inner wall of the sliding cylinder 3. The multi-fold tubes 20232 are connected by the stabilizing band 20234, and the multi-fold tubes 20232 are also connected to the sliding cylinder 3, thereby forming a stable multi-segment structure.

[0064] In order to reduce the flow rate of the fluid in the outer ring tube 2022, a pleated layer 20235 is provided on the inner side of the outer ring tube 2022, thereby slowing down the flow of the fluid.

[0065] Although the multi-channel reaction structure 202 can achieve a long diameter and sufficient reaction effect, since the structural path of the multi-channel reaction structure 202 is long and the route path is changeable, it is not easy to exchange heat, so that a lot of heat will accumulate in the reactor 1. Therefore, the present invention is based on the multi-channel reaction structure 202. A multi-stage heat exchange structure 203 is set, which is embedded in the inner side of the multi-channel reaction structure 202 and is in full contact with the multi-channel reaction structure 202, so as to achieve the effect of rapid heat exchange in multiple parts.

[0066] Specifically, the multi-stage heat exchange structure 203 includes a transverse accommodating portion 2031 tightly attached to the lower end of the uniformly distributed disk 201, and the lower end of the transverse accommodating portion 2031 is respectively connected to the transverse embedded portion 2032 and the longitudinal embedded portion 2033, and the transverse embedded portions 2032 are interconnected through the bending portion 2034. The transverse embedded portion 2032 is embedded in the gap between the outer ring tubes 2022, and the longitudinal embedded portion 2033 is embedded on the outside of the lower punch 2023. The transverse embedded portion 2032 and the longitudinal embedded portion 2033 at the bottom are connected to a bottom accommodating portion 2035, so that heat exchange can be carried out at all positions of the multi-channel reaction structure 202, and heat exchange packages can be carried out at multiple angles and multiple positions, thereby achieving the effect of simple heat exchange even for complex structures.

[0067] Heat exchange is mainly achieved through the circulation of the medium. Specifically, a heat flow guide inlet 20311 is provided on the horizontal accommodating portion 2031, and a heat flow guide outlet 20312 is provided on the bottom accommodating portion 2035. The heat flow guide inlet 20311 and the heat flow guide outlet 20312 are both connected to the heat exchange guide 204, so that the medium can be replaced and real-time heat exchange can be performed.

[0068] Example 2

[0069] Reference Figures 7 to 14As shown, another embodiment of the present invention further provides a phosphorus trifluoride purification device, which includes an adsorption tower body 10 for adsorbing phosphorus trifluoride, wherein the top of the adsorption tower body 10 is movably provided with an upper cover 20, and a plurality of air inlet ends are connected to the upper cover 20. The bottom of the adsorption tower body 10 is provided with an air outlet end 30, and further includes: a double-position sliding molecular sieve structure 40, comprising a first molecular sieve adsorption cylinder 41 provided at the bottom of the adsorption tower body 10, a second molecular sieve adsorption cylinder 42 is provided above the first molecular sieve adsorption cylinder 41, the first molecular sieve adsorption cylinder 41 and the second molecular sieve adsorption cylinder 42 are both locked to the inner wall of the adsorption tower body 10, the effective pore size of the second molecular sieve adsorption cylinder 42 is larger than that of the first molecular sieve adsorption cylinder 41, and the phosphorus trifluoride enters the first molecular sieve adsorption cylinder 41 after being adsorbed by the second molecular sieve adsorption cylinder 42; A pressure variable diameter adjustment structure 50 is arranged between the first molecular sieve adsorption cylinder 41 and the second molecular sieve adsorption cylinder 42. The pressure variable diameter adjustment structure 50 includes an elastic adjustment component 51 arranged on the inner side wall of the adsorption tower body 10. The upper and lower ends of the elastic adjustment component 51 are respectively connected to the first molecular sieve adsorption cylinder 41 and the second molecular sieve adsorption cylinder 42. A pressure regulating disk 52 is connected to the middle part of the elastic adjustment component 51. The pressure regulating disk 52 is provided with a plurality of holes 521 for chlorine trifluoride to pass through. An internal barrier structure 53 is provided in the hole 521. A top bone component 54 is fixed on the top of the first molecular sieve adsorption cylinder 41. When the pressure regulating disk 52 is pressurized and dropped, it will squeeze the top bone component 54, and cause the top bone component 54 to push out the internal barrier structure 53 in the hole 521, so that the inner diameter of the hole 521 becomes smaller.

[0070] The first molecular sieve adsorption cylinder 41 is located below the second molecular sieve adsorption cylinder 42 . In order to fix the first molecular sieve adsorption cylinder 41 , a supporting pocket 13 is provided at the bottom of the adsorption tower body 10 . The first molecular sieve adsorption cylinder 41 is installed in the supporting pocket 13 .

[0071] In the prior art, molecular sieves are often used to purify phosphorus trifluoride in the subsequent processing. The impurities of phosphorus trifluoride are treated in the final step by molecular sieves. When the molecular sieve is laid out, a very large containing skeleton is usually used to fill the molecular sieve into the skeleton. If the molecular sieve in the upper part is powdered and blocked, the molecular sieve in the lower part will directly become unusable and need to be replaced directly. Therefore, the present invention adopts a double-position sliding molecular sieve structure 40, and adopts a first molecular sieve adsorption cylinder 41 and a second molecular sieve adsorption cylinder 42 at both ends. The second molecular sieve adsorption cylinder 42 with a larger effective pore size is placed on the upper end of the first molecular sieve adsorption cylinder 41 with a larger volume, so that the second molecular sieve adsorption cylinder 42 withstands the first section pressure of the gas. Even if the second molecular sieve adsorption cylinder 42 is powdered, it is the upper half that needs to be replaced. Since the large-volume first molecular sieve adsorption cylinder 41 is set at the lower end, it is less likely to be directly hit by a large amount of high-pressure gas, thereby reducing its clogging phenomenon, and having a longer service life. At the same time, it is lower than the enterprise cost and has higher economic benefits.

[0072] The existing molecular sieve needs to be regenerated after being taken out, and its regeneration method often adopts the backflushing regeneration method. Since the first molecular sieve adsorption cylinder 41 and the second molecular sieve adsorption cylinder 42 need to be replaced, especially the second molecular sieve adsorption cylinder 42, the replacement frequency will be higher than the first molecular sieve adsorption cylinder 41, so it needs to be set to a movable state, but it cannot be in a suspended state. Therefore, the inner side of the adsorption tower body 10 of this embodiment is provided with a guide rail 11, and the outer wall of the adsorption tower body 10 is recessed inward to form an inner groove 12. The first molecular sieve adsorption cylinder 41 and the second molecular sieve adsorption cylinder 42 have the same structure. The first molecular sieve adsorption cylinder 41 includes a loading frame 411 for carrying molecular sieves, and a plurality of matching rib grooves 412 are provided on the outer side of the loading frame 411. After the loading frame 411 is placed in the adsorption tower body 10, the matching rib grooves 412 cooperate with the guide rail 11. A plurality of limiting members 413 are provided on the inner groove 12. The limiting members 413 pass through the guide rail 11 and are connected to the matching rib grooves 412. By providing the guide rail 11 on the inner side of the adsorption tower body 10 and providing the matching rib grooves 412 on the outer sides of the first molecular sieve adsorption cylinder 41 and the second molecular sieve adsorption cylinder 42, the first molecular sieve adsorption cylinder 41 and the second molecular sieve adsorption cylinder 42 can reach and be positioned at the designated positions by sliding them in, and the sealing can be ensured during the fixing process.

[0073] When the first molecular sieve adsorption cylinder 41 and the second molecular sieve adsorption cylinder 42 are replaced, the upper cover 20 needs to be removed. Once the upper cover 20 is removed, the residual gas in the equipment will leak out, which may cause pollution. Therefore, before removing the upper cover 20, the gas in the adsorption tower body 10 needs to be replaced. During the gas replacement, nitrogen is introduced through the nitrogen inlet at the top of the equipment, and the nitrogen is allowed to pass the gas in the adsorption tower body 10 and the molecular sieve through the nitrogen outlet at the bottom of the adsorption tower body 10, thereby ensuring safety after opening the upper cover 20.

[0074] In order to ensure the sealing effect, an alignment hole is opened on the inner groove 12, and the limiting member 413 includes a sealing gasket 4131 arranged on the alignment hole. A locking pin 4132 is installed on the sealing gasket 4131. The locking pin 4132 passes through the sealing gasket 4131 and is connected to the threaded hole on the matching rib groove 412. The limiting member 413 can fix the molecular sieve adsorption cylinder while preventing the gas flowing therein from leaking out.

[0075] Although the second molecular sieve adsorption cylinder 42 bears the pressure for the first molecular sieve adsorption cylinder 41, the first molecular sieve adsorption cylinder 41 may still be directly affected by the high-pressure gas. In order to protect the first molecular sieve adsorption cylinder 41 without affecting the filtration efficiency, the present invention provides a pressure variable diameter adjustment structure 50 on the basis of the double-position sliding molecular sieve structure 40. When the pressure of the incoming phosphorus trifluoride gas is too high, the pressure adjustment disk 52 installed on the elastic adjustment component 51 will be directly pressed down, so that the pressure adjustment disk 52 touches the top bone component 54, and the top bone component 54 pushes out the internal barrier structure 53 in the hole 521, thereby reducing the inner diameter of the hole 521, so that the gas after passing through the second molecular sieve adsorption cylinder 42 can pass through the hole 521 with a smaller area, so that the pressure and speed of the gas are reduced, thereby ensuring that the gas passes through the first molecular sieve adsorption cylinder 41 at a relatively uniform and stable speed, so that the gas is stably filtered and the life of the purification equipment is extended.

[0076] In order to sense the flow rate and pressure changes of the gas and automatically adjust its own state changes, in this embodiment, the elastic adjustment component 51 includes at least two elastic adjustment seats, and the elastic adjustment seat includes a first limit spring 511 arranged at the lower end of the second molecular sieve adsorption cylinder 42, and a second limit spring 512 is arranged on the edge of the upper end of the first molecular sieve adsorption cylinder 41. A mounting platform 513 is connected between the first limit spring 511 and the second limit spring 512, and the mounting platform 513 contains a pressure regulating disk 52. The pressure regulating disk 52 is set between the first limit spring 511 and the second limit spring 512, and the expansion and contraction amount of the first limit spring 511 and the second limit spring 512 is changed by the pressure when the gas enters, and then it is determined whether the internal barrier structure 53 in the pressure regulating disk 52 is triggered, so that the state can be automatically changed according to the change of the gas without manual monitoring.

[0077] It should be emphasized that the first limiting spring 511 and the second limiting spring 512 are sleeve-type springs, that is, the springs are limited by the sleeves to prevent them from falling out directly.

[0078] During the fixing process of the pressure regulating disk 52, it needs to change dynamically according to the status of the first limit spring 511 and the second limit spring 512. Therefore, the mounting platform 513 of this embodiment includes a C-type sleeve 5131 connected to the first limit spring 511 and the second limit spring 512. The opening of the C-type sleeve 5131 is used to accommodate the pressure regulating disk 52. The pressure regulating disk 52 is provided with a through hole on the side away from the opening. A positioning pin 5132 for locking the pressure regulating disk 52 is connected to the through hole. The pressure regulating disk 52 is slidably fixed to the inner side of the adsorption tower body 10 by the C-type sleeve 5131, and can move synchronously with the first limit spring 511 and the second limit spring 512, thereby achieving the effect of automatic adjustment.

[0079] When adjusting the gas pressure and volume, it is mainly done by adjusting the flow through the pressure regulating disk 52. Therefore, the pressure regulating disk 52 of this embodiment includes a pressure movable disk 522 connected to the C-type sleeve 5131, and the hole 521 is opened in the axial direction of the pressure movable disk 522. A plurality of axial flow channels 523 are opened on the inner side of the pressure movable disk 522. The axial flow channels 523 are laterally connected to a return flow channel 524, and the internal barrier structure 53 is located in the return flow channel 524. By providing the axial flow channel 523 on the pressure regulating disk 52, the gas passes through the axial flow channel 523, and when adjustment is required, the ventilation volume of the axial flow channel 523 is changed. Therefore, a return flow channel 524 is provided next to each axial flow channel 523, and the internal barrier structure 53 is provided in the return flow channel 524, so that the ventilation volume of the axial flow channel 523 can be changed.

[0080] It is the internal barrier structure 53 that changes the diameter of the axial flow channel 523. The internal barrier structure 53 includes a touch portion 531 located inside the return flow channel 524. The touch portion 531 is connected to a barrier portion 532. After the touch portion 531 is lifted up by the top bone component 54, the barrier portion 532 is pushed out, so that the barrier portion 532 extends into the axial flow channel 523. One end of the internal barrier structure 53 is triggered by the top bone component 54. When the entire pressure regulating disk 52 descends, it will contact the top bone component 54, thereby pushing out the touch portion 531, and then driving the barrier portion 532 to be pushed out, thereby realizing the change of the path. After the gas pressure drops, the pressure regulating disk 52 rises, and the barrier portion 532 will automatically swing down under the action of gravity without hindering the normal circulation of gas.

[0081] The blocking portion 532 is a folded piece having a plurality of flow holes. Even if some gas passes through the undeployed blocking portion 532 and enters the reflux channel 524 , it will be blocked by the top bone component 54 .

[0082] In the process of the top bone component 54 cooperating with the return flow channel 524, it needs to cooperate with several return flow channels 524 so as to achieve the effect of consistent regulation. Therefore, the top bone component 54 of this embodiment includes an extension rod seat 541 fixed on the top surface of the first molecular sieve adsorption cylinder 41, and the top surface of the extension rod seat 541 is connected to several separation rods 542. The separation rods 542 extend to the return flow channel 524 and are spaced apart from the touch portion 531. By setting the top bone component 54 to several separation rods 542, several separation rods 542 are coordinated with the descending return flow channel 524, so that the ventilation volume in all the return flow channels 524 can be consistently regulated, and the gas pressure can be better stabilized.

[0083] Since the action of changing the fluid flow rate is automatically adjusted inside the equipment, it is difficult for experimenters to know the condition of the internal molecular sieve and the replacement cycle of the molecular sieve. Therefore, the present invention sets a pressure detection structure inside the adsorption tower body 10. By detecting the gas pressure at different positions of the adsorption tower body 10, it can be determined whether the gas encounters resistance when passing through the molecular sieve, and then determine whether the molecular sieve needs to be replaced, thereby achieving the effect of mechanical self-adjustment and intelligent self-inspection.

[0084] Since the action of changing the fluid flow rate is automatically adjusted inside the equipment, it is difficult for experimenters to know the condition of the internal molecular sieve and the replacement cycle of the molecular sieve. Therefore, the pressure detection structure of this embodiment includes a first pressure detector 141 arranged at the top of the adsorption tower body 10, and a second pressure detector 142 is arranged at the bottom of the adsorption tower body 10. By arranging the pressure detection structure inside the adsorption tower body and detecting the gas pressure at different positions of the adsorption tower body, it is possible to determine whether the gas encounters resistance when passing through the molecular sieve, and then determine whether the molecular sieve needs to be replaced, thereby achieving the effect of mechanical self-adjustment and intelligent self-detection.

[0085] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for preparing phosphorus trifluoride, characterized in that: include: S1: Phosphorus trichloride and anhydrous hydrogen fluoride are added to the temperature-equalizing material exchange structure (2) of the reactor (1) respectively, the reaction temperature of the reactor (1) is maintained at 40 to 50°C, and the crude phosphorus trifluoride gas after the reaction is discharged from the discharge port (101) of the reactor (1); the reactor (1) is provided with a feeding seat (102), the temperature-equalizing material exchange structure (2) is locked on a sliding cylinder (3), the sliding cylinder (3) is slidably connected to the inner wall of the reactor (1), and the temperature-equalizing material exchange structure (2) includes a uniform distribution plate (201) movably installed in the reactor (1), and the uniform distribution plate (201) is connected to the inner wall of the reactor (1). The feeding seat (102) is connected to the uniform distribution plate (201), and a multi-channel reaction structure (202) is connected below the uniform distribution plate (201). A multi-stage heat exchange structure (203) is provided on the inner side of the multi-channel reaction structure (202). A plurality of heat exchange guide heads (204) are provided on the reactor (1). After the sliding cylinder (3) is loaded into the reactor (1), it rotates to allow the multi-channel reaction structure (202) to dock with the heat exchange guide heads (204). The phosphorus trichloride and anhydrous hydrogen fluoride are mixed through the feeding seat (102), the uniform distribution plate (201) and the multi-channel reaction structure (202) and then flow into the reactor (1); The multi-channel reaction structure (202) comprises a plurality of multi-stream columns (2021) connected to the uniformly distributed disk (201), wherein the length of the multi-stream columns (2021) gradually increases from left to right, and the multi-stream columns (2021) are connected to the outer ring tube (2022), and the outer ring tube (2022) is closely attached to the inner side of the sliding cylinder (3) and the outer ring tubes (2022) are spaced apart. A lower punch tube (2023) is provided on a side away from the uniform distribution disk (201); the outer ring tube (2022) is provided at different heights; the lower punch tube (2023) comprises a lower punch head (20231) connected to the outer ring tube (2022); a multi-fold tube (20232) is connected below the lower punch head (20231); and a distribution head (20233) is connected to the lower end of the multi-fold tube (20232); The multi-stage heat exchange structure (203) comprises a transverse accommodating portion (2031) closely attached to the lower end of the uniformly distributed plate (201), the lower end of the transverse accommodating portion (2031) being connected to the transverse embedding portion (2032) and the longitudinal embedding portion (2033), the transverse embedding portions (2032) being interconnected via a bending portion (2034), the transverse embedding portion (2032) being embedded in the gap between the outer ring tubes (2022), and the longitudinal embedding portion (2033) being embedded in the lower punch. On the outside of the tube (2023), the bottommost transverse embedded portion (2032) and the longitudinal embedded portion (2033) are connected to a bottom accommodating portion (2035); a heat flow guide inlet (20311) is provided on the transverse accommodating portion (2031); a heat flow guide outlet (20312) is provided on the bottom accommodating portion (2035); and both the heat flow guide inlet (20311) and the heat flow guide outlet (20312) are connected to the heat exchange guide (204); S2: condensing the crude phosphorus trifluoride gas and passing it into a first storage tank for storage, then heating the liquid in the first storage tank and pumping it into a flash evaporator for flash evaporation; S3: passing the flashed gas into a first distillation tower for rectification, returning the bottom product of the distillation in the first distillation tower, hydrogen fluoride, to the phosphorus trifluoride synthesis process, and condensing the top products of the distillation, phosphorus trifluoride and hydrogen chloride, and passing them into the intermediate first product storage tank; S4: Pumping the material in the intermediate first product storage tank into the second distillation tower for rectification, condensing the top gas of the second distillation tower, and refluxing part of the condensed product to the second distillation tower, and passing part to the first product storage tank for storage; S5: The finished product in the first product storage tank is pumped into the vaporizer for vaporization. The vaporized gas enters the gas-liquid separation tank for separation. The separated liquid flows back to the vaporizer. The separated gas is discharged from the top and sequentially passed into three phosphorus trifluoride purification equipment for purification. S6: The purified gas is filtered into the filter, and the filtered gas enters the second product storage tank. The gas in the second product storage tank is pressurized by the compressor and then enters the buffer tank for pressure-stabilized storage. After pressure stabilization, it enters the filling system for filling.

2. The method for preparing phosphorus trifluoride according to claim 1, wherein: The feeding seat (102) comprises a feeding tray (1021) arranged inside the reaction kettle (1). The top of the feeding tray (1021) is provided with a plurality of Y-shaped connectors (1022) penetrating the reaction kettle (1). The Y-shaped connectors (1022) are respectively connected to the input ends of phosphorus trichloride and anhydrous hydrogen fluoride.

3. The method for preparing phosphorus trifluoride according to claim 1, wherein: A blocking pile (103) is provided inside the reactor (1), a plurality of universal guide wheels (301) are provided on the outside of the sliding cylinder (3), a convection column (302) is provided at the bottom of the outer side of the sliding cylinder (3), and the convection column (302) is docked with the heat exchange guide head (204) after the sliding cylinder (3) rotates, and the bottom of the sliding cylinder (3) is attached to the blocking pile (103).

4. The method for preparing phosphorus trifluoride according to claim 1, wherein: Adjacent multi-fold tubes (20232) are connected via stabilizing bands (20234), and the stabilizing bands (20234) on the outermost multi-fold tubes (20232) are connected to the inner wall of the sliding cylinder (3).

5. The method for preparing phosphorus trifluoride according to claim 1, wherein: A pleated layer (20235) is provided on the inner side of the outer ring tube (2022).

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