A continuous preparation device and method for phosphorus pentachloride

Abstract

The invention discloses a phosphorus pentachloride continuous preparation device and a preparation method. The device comprises a reactor, wherein the top of the reactor is connected with a phosphorus trichloride feeding pipeline, the bottom of the reactor is connected with a chlorine feeding pipeline, a rotating shaft is vertically arranged in the reactor, a screw belt for squeezing materials to form a dense isolation layer is arranged at the lower side of the rotating shaft close to the chlorine feeding pipeline, a material level meter is arranged at the bottom of the reactor, and an electric rotary valve is arranged at the discharge pipe position at the bottom of the reactor. The device can continuously discharge products in the process of continuously producing phosphorus pentachloride, and chlorine will not be caused to escape downwards in the process of discharging the products.

Description

Technical Field

[0001] The invention relates to the technical field of phosphorus pentachloride production, in particular to a phosphorus pentachloride continuous preparation device and a preparation method. Background Art

[0002] At present, the production of phosphorus pentachloride mostly adopts the traditional kettle production process, that is, phosphorus trichloride and chlorine are used as raw materials.

[0003] A certain amount of liquid phosphorus trichloride is first injected into the stirred reactor, and then chlorine is introduced to react in a gas-liquid contact manner. This process has the disadvantages of incomplete reaction, poor working environment, viscous reaction system with large stirring resistance, low purity of product inclusions, low yield, and intermittent production, which cannot meet the needs of industrial continuous production.

[0004] For this purpose, relevant researchers have also developed corresponding equipment and processes for continuous production of phosphorus pentachloride. For example, CN112919439A - A method and device for continuously preparing high-purity phosphorus pentachloride discloses the following content: A device for continuously preparing high-purity phosphorus pentachloride comprises: a reactor and a buffer tank, wherein a phosphorus trichloride feed inlet and a mixed gas inlet are provided in the middle of the reactor, a phosphorus pentachloride discharge outlet is provided at the bottom, and a tail gas outlet is provided at the top, a closed circulation loop is formed between the tail gas outlet and the mixed gas inlet, and a circulation fan is connected in series to the circulation loop; a chlorine inlet, a tail gas recovery port and a mixed gas outlet are respectively provided on the buffer tank, and the buffer tank is connected in series to the circulation loop through the tail gas recovery port and the mixed gas outlet. When the preparation device is used, the mixed gas enters the reactor through the mixed gas inlet through the circulating fan, and the phosphorus trichloride enters the reactor through the phosphorus trichloride feed port. Since the phosphorus trichloride feed port and the mixed gas inlet are both located in the middle of the reactor, the phosphorus trichloride in the reactor reacts with the chlorine in the mixed gas to form fine phosphorus pentachloride crystals floating in the upper part of the reactor, forming a fluidized reaction system. As the reaction proceeds, the phosphorus pentachloride crystals gradually grow into particles and settle at the bottom of the reactor under the action of gravity. After the reaction is completed, the product high-purity phosphorus pentachloride is collected through the phosphorus pentachloride discharge port. The above process can continuously produce phosphorus pentachloride by continuously introducing phosphorus trichloride and chlorine, but the process has the following problems that cannot be ignored:

[0005] First, each time the reaction is completed, the product high-purity phosphorus pentachloride needs to be discharged through the phosphorus pentachloride discharge outlet, so the phosphorus pentachloride is produced batch by batch, and the so-called continuous preparation process also has the process of stopping production during the discharge interval, which undoubtedly reduces the degree of continuous production and reduces the production efficiency. Second, the reason why each batch needs to be discharged through the phosphorus pentachloride discharge outlet after the reaction is completed is that chlorine gas can easily escape from the phosphorus pentachloride discharge outlet. If the continuous production is carried out while discharging, the chlorine gas will inevitably escape downward with the discharge of phosphorus pentachloride, causing a serious safety threat to the plant environment. In addition, it should be noted that since the phosphorus pentachloride grains generated continuously gradually grow into particles and settle on the inner bottom of the reactor under the action of gravity, the phosphorus pentachloride particles are in a fluffy state, so even if the phosphorus pentachloride particles have a certain thickness, during the continuous production and discharge process, chlorine gas can easily escape downward from the gaps between the phosphorus pentachloride particles. Summary of the invention

[0006] The object of the present invention is to overcome the above-mentioned disadvantages and provide a continuous preparation device and method for phosphorus pentachloride, which can continuously discharge the product during the continuous production of phosphorus pentachloride and will not cause chlorine to escape downward during the discharge of the product.

[0007] The present invention solves the above technical problems and adopts the following technical scheme: a phosphorus pentachloride continuous preparation device comprises a reactor, wherein the top of the reactor is connected with a phosphorus trichloride feeding pipeline, and the bottom of the reactor is connected with a chlorine feeding pipeline, a rotating shaft is vertically arranged in the reactor, a screw belt for squeezing materials to form a dense isolation layer is arranged at the lower side of the rotating shaft close to the chlorine feeding pipeline, a material level meter is arranged at the bottom of the reactor, and an electric rotary valve is arranged at the discharge pipe position at the bottom of the reactor.

[0008] Preferably, the signal output terminal of the material level meter is connected to the input terminal of the controller, and the control signal output terminal of the controller is connected to the signal input terminal of the electric rotary valve.

[0009] Preferably, the upper side of the rotating shaft is connected to the scraper through a connecting rod, and the top of the rotating shaft is connected to the output shaft of the rotating motor.

[0010] Preferably, the discharge pipe at the bottom of the reactor is connected to the spiral ribbon product tank through a screw conveyor; the spiral ribbon is a double spiral ribbon structure.

[0011] Preferably, the gas outlet at the top of the reactor is connected to the gas inlet end of the chlorine cooler through a gas outlet pipeline, and the gas outlet end of the chlorine cooler is connected to the chlorine feed pipeline through a gas return pipeline; the phosphorus trichloride feed pipeline is connected to the phosphorus trichloride metering tank, and a magnetic pump is provided on the phosphorus trichloride feed pipeline.

[0012] Preferably, the return gas pipeline is provided with a first chlorine buffer tank, a chlorine circulation machine and a second chlorine buffer tank in sequence, and the first chlorine buffer tank is also connected to the chlorine supply pipeline.

[0013] Preferably, a filter is provided at the air outlet on the top of the reactor, and an electric heating belt is provided on the outside of the filter.

[0014] Preferably, a chlorine backflush pipeline is provided between the filter outlet and the chlorine feed pipeline, a first valve is provided on the chlorine backflush pipeline, a second valve is provided on the chlorine feed pipeline near the bottom side of the reactor, and a third valve is provided on the gas outlet pipeline.

[0015] In addition, the present invention also discloses a preparation method of the above-mentioned phosphorus pentachloride continuous preparation device, which comprises the following steps:

[0016] S1: The phosphorus trichloride liquid in the phosphorus trichloride feed pipeline is continuously sprayed downward through the atomizing nozzle on the top of the reactor;

[0017] S2: Chlorine in the chlorine feed pipeline continuously enters the reactor from the bottom side of the reactor, and then reacts with phosphorus trichloride liquid to obtain solid phosphorus pentachloride material;

[0018] S3: The phosphorus pentachloride material is deposited at the bottom of the reactor. When the rotating motor is turned on, it drives the rotating shaft to rotate, thereby causing the spiral belt to rotate, thereby squeezing the phosphorus pentachloride material to form a dense isolation layer. At this time, the chlorine introduced from the chlorine feed pipeline will not be discharged downward from the discharge port at the bottom of the reactor due to the barrier of the dense isolation layer of the phosphorus pentachloride material, but can only pass upward inside the reactor and mix with the phosphorus trichloride liquid for reaction;

[0019] S4: After the electric rotary valve is opened, the phosphorus pentachloride material moves downward under the rotation of the spiral belt, and is continuously discharged downward at a certain flow rate under the control of the electric rotary valve and enters the screw conveyor. At this time, the dense isolation layer of the phosphorus pentachloride material at the bottom of the reactor is always maintained at a certain thickness, and the lower surface of the dense isolation layer of the phosphorus pentachloride material continuously discharges from the discharge port at the bottom of the reactor, while the upper surface of the dense isolation layer of the phosphorus pentachloride material always blocks the introduced chlorine gas to prevent it from escaping from the discharge port;

[0020] S5: The phosphorus pentachloride material entering the screw conveyor is then sent into the screw ribbon product tank, and then packaged by the packaging machine before being shipped out.

[0021] Furthermore, it also includes the step of backwashing the filter arranged at the gas outlet at the top of the reactor by using the chlorine gas feed pipeline:

[0022] S6: At regular intervals, close the second valve on the chlorine feed pipeline and the third valve on the gas outlet pipeline, and open the first valve on the chlorine backflush pipeline. At this time, the chlorine passes through the filter in the reverse direction from the chlorine backflush pipeline to perform a backwashing process.

[0023] Beneficial effects of the present invention:

[0024] 1. The present invention can continuously discharge the product during the continuous production of phosphorus pentachloride, and will not cause chlorine to escape downward during the product discharge process.

[0025] 2. The present invention can extrude the phosphorus pentachloride material to form a dense isolation layer by adding a rotating spiral belt. At this time, the chlorine introduced from the chlorine feed pipeline will not be discharged downward from the discharge port at the bottom of the reactor due to the barrier of the dense isolation layer of the phosphorus pentachloride material, but can only pass upward inside the reactor and react with the phosphorus trichloride liquid. This ensures that the chlorine will not escape downward during the continuous discharge of the product.

[0026] 3. The spiral ribbon in the present invention can also play a role in promoting the discharge of phosphorus pentachloride material, and can push the entire dense isolation layer of phosphorus pentachloride material to move downward, so that the lower surface of the dense isolation layer of phosphorus pentachloride material can be continuously discharged from the discharge port at the bottom of the reactor.

[0027] 4. In the present invention, under the regulation of the electric rotary valve, the phosphorus pentachloride material can be continuously discharged downward at a certain flow rate and enter the screw conveyor. By controlling the discharge flow rate of the electric rotary valve, the dense isolation layer of the phosphorus pentachloride material at the bottom of the reactor can always be kept at a certain thickness. At this time, the lower surface of the dense isolation layer of the phosphorus pentachloride material continuously discharges from the discharge port at the bottom of the reactor, while the upper surface of the dense isolation layer of the phosphorus pentachloride material always blocks the introduced chlorine gas to prevent it from escaping downward from the discharge port;

[0028] 5. The present invention can introduce chlorine gas to backwash the filter by adding a chlorine backwash pipeline, thereby ensuring the filtering performance of the filter. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural schematic diagram of a device for continuously preparing phosphorus pentachloride;

[0030] Figure 2 for Figure 1 A schematic diagram of the enlarged structure of the area where the reactor is located. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0032] like Figure 1 and 2As shown, a phosphorus pentachloride continuous preparation device comprises a reactor 1, the top of the reactor 1 is connected to a phosphorus trichloride feed pipeline 2, the bottom of the reactor 1 is connected to a chlorine feed pipeline 3, a rotating shaft 4 is vertically arranged in the reactor 1, a screw belt 5 for squeezing materials to form a dense isolation layer is arranged at the lower side of the rotating shaft 4 close to the chlorine feed pipeline 3, a material level meter 6 is arranged at the bottom of the reactor 1, and an electric rotary valve 7 is arranged at the discharge pipe position at the bottom of the reactor 1.

[0033] Preferably, the signal output end of the material level meter 6 is connected to the input end of the controller, and the signal output end of the controller is connected to the signal input end of the electric rotary valve 7. In this embodiment, in order to keep the dense isolation layer of the phosphorus pentachloride material at the bottom of the reactor 1 at a certain thickness, it can be monitored by the material level meter 6. When it is detected that the dense isolation layer of the phosphorus pentachloride material is thin, the controller controls the discharge flow of the electric rotary valve 7 to decrease, so that the thickness of the dense isolation layer of the phosphorus pentachloride material increases to a normal range. When it is detected that the dense isolation layer of the phosphorus pentachloride material is thick, the controller controls the discharge flow of the electric rotary valve 7 to increase, so that the thickness of the dense isolation layer of the phosphorus pentachloride material decreases to a normal range. Preferably, the controller in this embodiment can use Siemens S7-300PLC controller.

[0034] Preferably, the upper side of the rotating shaft 4 is connected to the scraper 9 through a connecting rod 8, and the top of the rotating shaft 4 is connected to the output shaft of the rotating motor 10. In order to prevent the material from adhering to the side wall of the reactor 1, by adding the connecting rod 8 and the scraper 9, when the rotating shaft 4 rotates, the scraper 9 can be driven to rotate accordingly, thereby continuously scraping the side wall of the reactor 1, effectively preventing the phosphorus pentachloride crystals from adhering to the side wall of the reactor 1.

[0035] Preferably, the discharge pipe at the bottom of the reactor 1 is connected to the ribbon product tank 12 through a screw conveyor 11; the ribbon 5 is a double-ribbon structure. The phosphorus pentachloride material continuously discharged from the discharge pipe at the bottom of the reactor 1 can be directly and continuously conveyed to the ribbon product tank 12 through the screw conveyor 11, stirred by its own ribbon, and then discharged to the packaging machine below, and shipped out after packaging. The double-ribbon structure is more uniform and has a larger extrusion surface range for the material, so the material can be extruded more evenly.

[0036] Preferably, the gas outlet at the top of the reactor 1 is connected to the gas inlet end of the chlorine cooler 14 through the gas outlet pipeline 13, and the gas outlet end of the chlorine cooler 14 is connected to the chlorine feed pipeline 3 through the gas return pipeline 15; the phosphorus trichloride feed pipeline 2 is connected to the phosphorus trichloride metering tank 16, and a magnetic pump 17 is provided on the phosphorus trichloride feed pipeline 2. The phosphorus trichloride liquid in the phosphorus trichloride metering tank 16 can be pumped into the chlorine feed pipeline 3 by the magnetic pump 17, and then sent to the top of the reactor 1.

[0037] Preferably, the return gas pipeline 15 is provided with a first chlorine buffer tank 18, a chlorine circulation machine 19 and a second chlorine buffer tank 20 in sequence, and the first chlorine buffer tank 18 is also connected to the chlorine gas supply pipeline 21. By providing the first chlorine buffer tank 18, the pressure of the chlorine gas can be effectively buffered to protect the chlorine circulation machine 19, and by providing the second chlorine buffer tank 20, the chlorine gas can be effectively buffered to prevent the impact of excessive pressure on the reactor 1, and the chlorine circulation machine 19 acts as a circulation pump, so that the chlorine gas can be circulated into the reactor 1 for reaction; in addition, part of the chlorine gas lost by the reaction in the reactor 1 can be supplemented through the chlorine gas supply pipeline 21.

[0038] Preferably, the air outlet at the top of the reactor 1 is further provided with a filter 22, and an electric heating belt 23 is provided outside the filter 22. When the chlorine gas rises and leaves from the air outlet at the top of the reactor 1, solid phosphorus pentachloride is mixed therein. In order to avoid material loss, the filter 22 can filter out the solid phosphorus pentachloride in the gas, and the electric heating belt 23 can heat the filter 22, so that during the backwashing process of the filter 22, the material attached to the filter screen of the filter 22 is easier to leave, thereby improving the backwashing effect.

[0039] Preferably, a chlorine backflush pipeline 24 is further provided between the outlet of the filter 22 and the chlorine feed pipeline 3, a first valve 25 is provided on the chlorine backflush pipeline 24, a second valve 26 is provided on the chlorine feed pipeline 3 near the bottom side of the reactor 1, and a third valve 27 is provided on the gas outlet pipeline 13. Chlorine can be introduced through the chlorine backflush pipeline 24 to backwash the filter 22, thereby ensuring the filtering performance of the filter 22.

[0040] In addition, the present invention also discloses a preparation method of the above-mentioned phosphorus pentachloride continuous preparation device, which comprises the following steps:

[0041] S1: The phosphorus trichloride liquid in the phosphorus trichloride feed pipeline 2 is continuously sprayed downward through the atomizing nozzle at the top of the reactor 1;

[0042] S2: Chlorine in the chlorine feed pipeline 3 continuously enters the reactor 1 from the bottom side of the reactor 1, and then reacts with the phosphorus trichloride liquid to obtain a solid phosphorus pentachloride material;

[0043] S3: The phosphorus pentachloride material is deposited at the bottom of the reactor 1. When the rotating motor 10 is turned on, it drives the rotating shaft 4 to rotate, thereby rotating the spiral belt 5, thereby squeezing the phosphorus pentachloride material to form a dense isolation layer. At this time, the chlorine introduced from the chlorine feed pipeline 3 will not be discharged downward from the discharge port at the bottom of the reactor 1 due to the barrier of the dense isolation layer of the phosphorus pentachloride material, but can only pass upward inside the reactor 1 and mix with the phosphorus trichloride liquid for reaction;

[0044] S4: After the electric rotary valve 7 is opened, the phosphorus pentachloride material moves downward under the rotation of the spiral ribbon 5, and is continuously discharged downward at a certain flow rate under the control of the electric rotary valve 7 and enters the screw conveyor 11. At this time, the dense isolation layer of the phosphorus pentachloride material at the bottom of the reactor 1 is always maintained at a certain thickness, and the lower surface of the dense isolation layer of the phosphorus pentachloride material is continuously discharged from the discharge port at the bottom of the reactor 1, while the upper surface of the dense isolation layer of the phosphorus pentachloride material always blocks the introduced chlorine gas to prevent it from escaping from the discharge port;

[0045] S5: The phosphorus pentachloride material entering the screw conveyor 11 is then sent into the screw ribbon product tank 12, and then packaged by the packaging machine before being shipped out.

[0046] Furthermore, it also includes the step of backwashing the filter 22 arranged at the top gas outlet of the reactor 1 by using the chlorine gas feed pipeline 3:

[0047] S6: At regular intervals, close the second valve 26 on the chlorine feed pipeline 3 and the third valve 27 on the gas outlet pipeline 13, and open the first valve 25 on the chlorine backflush pipeline 24. At this time, the chlorine passes through the filter 22 from the chlorine backflush pipeline 24 in the reverse direction to perform a backwashing process on it.

[0048] The above-mentioned embodiments are only preferred technical solutions of the present invention and should not be regarded as limitations of the present invention. The embodiments and features in the embodiments of the present application can be arbitrarily combined with each other without conflict. The protection scope of the present invention shall be the technical solutions recorded in the claims, including the equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A device for continuously preparing phosphorus pentachloride, comprising a reactor (1), wherein the top of the reactor (1) is connected to a phosphorus trichloride feed pipeline (2), and the bottom of the reactor (1) is connected to a chlorine gas feed pipeline (3), characterized in that: A rotating shaft (4) is vertically arranged in the reactor (1); a screw belt (5) for squeezing materials to form a dense isolation layer is arranged at the lower side of the rotating shaft (4) near the chlorine gas feed pipeline (3); a material level meter (6) is arranged at the bottom side of the reactor (1); and an electric rotary valve (7) is arranged at the discharge pipe at the bottom of the reactor (1); The upper side of the rotating shaft (4) is connected to the scraper (9) via a connecting rod (8), and the top of the rotating shaft (4) is connected to the output shaft of the rotating motor (10); The discharge pipe at the bottom of the reactor (1) is connected to the spiral ribbon product tank (12) via a screw conveyor (11); the spiral ribbon (5) is a double spiral ribbon structure; The air outlet at the top of the reactor (1) is also provided with a filter (22), and an electric heating belt (23) is provided on the outside of the filter (22); A chlorine backflush pipeline (24) is provided between the outlet of the filter (22) and the chlorine feed pipeline (3), and a first valve (25) is provided on the chlorine backflush pipeline (24). A second valve (26) is provided on the chlorine feed pipeline (3) at a position close to the bottom side of the reaction kettle (1), and a third valve (27) is provided on the gas outlet pipeline (13).

2. A phosphorus pentachloride continuous preparation device according to claim 1, characterized in that: The signal output end of the material level meter (6) is connected to the input end of the controller, and the control signal output end of the controller is connected to the signal input end of the electric rotary valve (7).

3. A continuous preparation device for phosphorus pentachloride according to claim 1, characterized in that: The gas outlet at the top of the reactor (1) is connected to the gas inlet end of a chlorine cooler (14) via a gas outlet pipeline (13); the gas outlet end of the chlorine cooler (14) is connected to a chlorine feed pipeline (3) via a gas return pipeline (15); the phosphorus trichloride feed pipeline (2) is connected to a phosphorus trichloride metering tank (16); and a magnetic pump (17) is provided on the phosphorus trichloride feed pipeline (2).

4. A phosphorus pentachloride continuous preparation device according to claim 3, characterized in that: The return gas pipeline (15) is provided with a first chlorine buffer tank (18), a chlorine circulation machine (19) and a second chlorine buffer tank (20) in sequence, and the first chlorine buffer tank (18) is also connected to the chlorine supply pipeline (21).

5. A method for preparing phosphorus pentachloride using the phosphorus pentachloride continuous preparation device according to any one of claims 1 to 4, characterized in that: It includes the following steps: S1: The phosphorus trichloride liquid in the phosphorus trichloride feed pipeline (2) is continuously sprayed downward through the atomizing nozzle at the top of the reactor (1); S2: Chlorine in the chlorine feed pipeline (3) continuously enters the reactor (1) from the bottom side of the reactor (1), and then reacts with the phosphorus trichloride liquid to obtain a solid phosphorus pentachloride material; S3: The phosphorus pentachloride material is deposited at the bottom of the reactor (1). When the rotating motor (10) is turned on, it drives the rotating shaft (4) to rotate, thereby causing the spiral belt (5) to rotate, thereby squeezing the phosphorus pentachloride material to form a dense isolation layer. At this time, the chlorine gas introduced from the chlorine gas feed pipeline (3) will not be discharged downward from the bottom outlet of the reactor (1) due to the obstruction of the dense isolation layer of the phosphorus pentachloride material, but can only pass upward inside the reactor (1) and mix with the phosphorus trichloride liquid for reaction; S4: After the electric rotary valve (7) is opened, the phosphorus pentachloride material moves downward under the rotation of the spiral ribbon (5), and is continuously discharged downward at a certain flow rate under the control of the electric rotary valve (7) and enters the screw conveyor (11). At this time, the dense isolation layer of the phosphorus pentachloride material at the bottom of the reactor (1) is always maintained at a certain thickness, and the lower surface of the dense isolation layer of the phosphorus pentachloride material continuously discharges from the discharge port at the bottom of the reactor (1), while the upper surface of the dense isolation layer of the phosphorus pentachloride material always blocks the introduced chlorine gas to prevent it from escaping from the discharge port; S5: The phosphorus pentachloride material entering the screw conveyor (11) is then conveyed into the screw ribbon product tank (12), and then packaged by a packaging machine before being shipped out of the warehouse.

6. The method for preparing phosphorus pentachloride by the phosphorus pentachloride continuous preparation device according to claim 5, characterized in that: The method further comprises the step of backwashing the filter (22) arranged at the top gas outlet of the reactor (1) by using the chlorine gas feed pipeline (3): S6: At regular intervals, the second valve (26) on the chlorine feed pipeline (3) and the third valve (27) on the gas outlet pipeline (13) are closed, and the first valve (25) on the chlorine backflush pipeline (24) is opened. At this time, the chlorine gas passes through the filter (22) in the reverse direction from the chlorine backflush pipeline (24) to perform a backwashing process.

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