A continuous production system and method of phosphorus oxychloride

Abstract

The present application relates to a continuous production system and method of phosphorus oxychloride, wherein raw material phosphorus trichloride and oxygen are continuously metered into a reactor for oxidation reaction, and the reaction liquid material composition is stabilized by controlling the reaction temperature and pressure, a jet cyclone pressure stabilizing condenser and a pressure stabilizing tank are used to completely react and continuously meter out the trace oxygen released by the reaction liquid pressure release, after distillation separation, the light and heavy components are continuously metered out from the top and bottom of the distillation column, wherein the lighter components control the liquid level in the distillation column by adjusting the reflux ratio of the reflux ratio controller, at the same time, the unreacted phosphorus trichloride raw material is recovered into the phosphorus trichloride receiving tank, and the heavier phosphorus oxychloride product component at the bottom is output from the product output pipeline at the lower side of the reboiler. The present application couples the oxidation reaction of phosphorus trichloride and oxygen and distillation, realizes the continuous production operation of phosphorus oxychloride, improves the production efficiency and capacity, and reduces the energy consumption.

Description

Technical Field

[0001] This invention relates to the field of chemical production, specifically to a continuous production system and method for phosphorus oxychloride. Background Technology

[0002] Phosphorus oxychloride is widely used in the production of pesticides, pharmaceuticals, dyes, phosphate esters, and flame retardants. It can be used as a raw material, intermediate, chlorinating agent, catalyst, and extractant. Early mainstream production processes for phosphorus oxychloride in China were the phosphorus trichloride chlorination and hydrolysis process. Later, the phosphorus trichloride oxygen oxidation process gradually replaced the original process. The initial oxygen oxidation process mainly used a multi-reactor series bubbling method. However, with the gradual introduction of national carbon emission policies, how to achieve a green and low-carbon production process for phosphorus oxychloride has attracted much attention. Because the oxygen oxidation process is an exothermic reaction with a large amount of heat released, the rapid removal of the reaction heat from the reaction system during the fast reaction phase places high demands on the plant's circulating cooling water and other utilities. Furthermore, the inefficient use of reaction heat leads to energy waste and reduces production efficiency. Summary of the Invention

[0003] The purpose of this invention is to provide a continuous production system and method for phosphorus oxychloride, which couples the oxidation reaction of phosphorus trichloride with oxygen and distillation to achieve continuous production of phosphorus oxychloride, thereby improving production efficiency and capacity while reducing energy consumption.

[0004] The objective of this invention is achieved through the following technical solution:

[0005] A continuous production system for phosphorus oxychloride includes a preheater, a phosphorus trichloride receiving tank, a reactor, a reboiler, a distillation column, a top condenser, a jet cyclone-type pressure-stabilizing condenser, and multiple pipelines. The phosphorus trichloride feedstock inlet pipeline is connected to the feedstock inlet of the preheater. The feedstock outlet of the preheater is connected to the first tank inlet of the phosphorus trichloride receiving tank via a feedstock transfer pipeline. The tank outlet of the phosphorus trichloride receiving tank is connected to the first reaction inlet of the reactor via a phosphorus trichloride delivery pipeline. An oxygen inlet pipeline is connected to the second reaction inlet of the reactor. The material outlet of the reactor is connected to the heat exchange tube inlet of the reboiler via a first circulation pipeline. The heat exchange tube outlet of the reboiler is connected to the third reaction inlet of the reactor via a second circulation pipeline. The distillation column is located above the reboiler, and its interior is connected to the reboiler interior. The second circulation pipeline has a circulation branch connecting to the jet cyclone-type pressure-stabilizing condenser. The inlet of the flow-type pressure-stabilized condenser is connected to the output of the jet cyclone pressure-stabilized condenser, which is connected to the first column inlet of the distillation column via a feed line. A pressure-stabilizing tank is provided on the feed line. The outlet of the upper column is connected to the inlet of the top condenser via a connecting pipe. The outlet of the top condenser is connected to the input of a reflux ratio controller. The first output of the reflux ratio controller is connected to the second column inlet at the upper end of the distillation column via a first branch. The second output of the reflux ratio controller is connected to the inlet of the second tank at the upper end of the phosphorus trichloride receiving tank via a second branch. A material outlet is provided on the lower side of the reboiler, and the distilled material in the distillation column is output from the material outlet. The material outlet is connected to the inlet of the preheating tube in the preheater via a finished product output pipe. The outlet of the preheating tube in the preheater is connected to the finished product collection unit.

[0006] The jet vortex pressure-stabilized condenser includes a vortex condenser shell and ejectors and cooling guide coils disposed within the vortex condenser shell. A pressure relief pipe is provided on the circulation branch, and the output end of the circulation branch forms multiple branches that are respectively connected to the corresponding ejectors.

[0007] The jet vortex pressure-stabilizing condenser contains 1-2 ejectors, and the material jetting direction is offset downwards by 10-30° along the horizontal direction of the vortex condenser shell. The ratio of the upper and lower diameters of the vortex condenser shell is 1.05:1-5:1.

[0008] A raw material flow meter is installed on the phosphorus trichloride raw material input pipeline.

[0009] The phosphorus trichloride conveying pipeline is equipped with a phosphorus trichloride conveying pump and a phosphorus trichloride flow meter in sequence along the material conveying direction.

[0010] An oxygen flow meter is installed on the oxygen input pipeline.

[0011] A circulation pump is installed on the first circulation pipeline.

[0012] The material inlet pipeline is equipped with a pressure stabilizing tank and a material inlet flow meter in sequence along the material transmission direction.

[0013] The finished product collection unit includes a finished product conveying pump, a finished product flow meter, and a finished product tank connected in series.

[0014] A method for the continuous production system of phosphorus oxychloride, characterized by comprising the following steps:

[0015] Step 1: Add phosphorus trichloride to the reactor and phosphorus oxychloride to the reboiler;

[0016] Step 2: Open the first circulation pipeline and the oxygen input pipeline, and control the oxygen intake, pressure and temperature parameters of the reactor. At the same time, adjust the distillation column to total reflux until the system is running stably.

[0017] Step 3: Turn on the jet cyclone condenser and the feed pipeline to the tower, and control the feed rate and feed temperature of the distillation column reaction liquid, while adjusting the reflux ratio controller;

[0018] Step 4: Open the connecting pipeline to the top condenser and the finished product output pipeline below the reboiler to achieve continuous collection from the top and bottom of the distillation column. At the same time, open the phosphorus trichloride delivery pipeline to continuously feed into the reactor and control the phosphorus trichloride feed rate. The system will then start to operate stably.

[0019] Step 5: After the system's feeding and discharging operations are stable, monitor the status of each part of the system and make timely fine adjustments.

[0020] The advantages and positive effects of this invention are as follows:

[0021] 1. This invention continuously meteres and feeds phosphorus trichloride and oxygen into a reactor for oxidation reaction. By controlling the reaction temperature and pressure, the composition of the reaction liquid is stabilized. A jet cyclone condenser and a pressure stabilizing tank completely react the trace amounts of oxygen released from the depressurized reaction liquid and continuously meter it out for distillation. After distillation separation, light and heavy components are continuously metered and collected from the top and bottom of the distillation column. The lighter components are controlled by adjusting the reflux ratio of the reflux ratio controller to control the liquid level in the distillation column, while the unreacted phosphorus trichloride feedstock is recovered to the phosphorus trichloride receiving tank. The heavier phosphorus oxychloride product component at the bottom of the column is output through the product output pipeline below the reboiler, thereby realizing continuous production operation of phosphorus oxychloride. This invention has a high and stable oxidation reaction rate, and compared with similar circulating batch processes, the production capacity is more than doubled. The process operation is flexible and stable.

[0022] 2. This invention utilizes a reboiler as the main unit for recovering the heat of oxidation reaction. The reaction liquid serves as a heat source, continuously providing heat to the distillation material through the heat exchange tubes within the reboiler. Additionally, the finished product output pipeline enters the preheating pipeline within the preheater to preheat the raw material phosphorus trichloride, thus recovering some of the reaction heat. Calculations show that this invention reduces energy consumption per ton of product by approximately half, thereby improving both environmental and economic benefits. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the present invention.

[0024] Figure 2 for Figure 1 A schematic diagram of a medium-jet cyclone stabilizing condenser.

[0025] Figure 3 for Figure 2 Top view of a medium-jet vortex-type pressure-stabilized condenser.

[0026] Among them, 1 is a phosphorus trichloride receiving tank, 2 is a phosphorus trichloride delivery pipeline, 201 is a phosphorus trichloride delivery pump, 202 is a phosphorus trichloride flow meter, 3 is a finished product collection unit, 301 is a finished product delivery pump, 302 is a finished product flow meter, 303 is a finished product tank, 4 is an oxygen input pipeline, 401 is an oxygen flow meter, 5 is a reactor, 6 is a first circulation pipeline, 601 is a circulation pump, 7 is a reboiler, 701 is a heat exchange tube, 8 is a jet cyclone pressure-stabilizing condenser, 801 is an ejector, 80 2 is the cooling guide coil, 803 is the cyclone condenser shell, 9 is the second circulation pipeline, 901 is the circulation branch, 10 is the distillation column, 11 is the inlet material pipeline, 111 is the pressure stabilizing tank, 112 is the inlet material flow meter, 12 is the top condenser, 13 is the reflux ratio controller, 131 is the first branch, 132 is the second branch, 14 is the preheater, 15 is the phosphorus trichloride feedstock input pipeline, 151 is the feedstock flow meter, 16 is the finished product output pipeline, and 17 is the feedstock transfer pipeline. Detailed Implementation

[0027] The invention will now be described in further detail with reference to the accompanying drawings.

[0028] like Figures 1-3As shown, the present invention includes a preheater 14, a phosphorus trichloride receiving tank 1, a reactor 5, a reboiler 7, a distillation column 10, a top condenser 12, a jet cyclone-type pressure-stabilizing condenser 8, and multiple pipelines. The phosphorus trichloride feedstock input pipeline 15 is connected to the feedstock inlet of the preheater 14. The feedstock outlet of the preheater 14 is connected to the first tank inlet of the phosphorus trichloride receiving tank 1 via a feedstock transfer pipeline 17. The tank outlet of the phosphorus trichloride receiving tank 1 is connected to the first reaction inlet of the reactor 5 via a phosphorus trichloride conveying pipeline 2. The oxygen input pipeline 4 is connected to the second reaction inlet of the reactor 5. The material outlet of the reactor 5 is connected to the inlet of the heat exchange tube 701 in the reboiler 7 via a first circulation pipeline 6. The outlet of the heat exchange tube 701 in the reboiler 7 is connected to the third reaction inlet of the reactor 5 via a second circulation pipeline 9. The distillation column 10 is located above the reboiler 7, and the interior of the distillation column 10 communicates with the interior of the reboiler 7. The second circulation pipeline 9 has a circulation branch 901 connected to the jet cyclone-type pressure-stabilizing condenser 8. The input port of the pressure-stabilizing condenser 8 is connected, and the output port of the jet cyclone pressure-stabilizing condenser 8 is connected to the first column inlet of the distillation column 10 through the column feed pipeline 11. The column feed pipeline 11 is equipped with a pressure-stabilizing tank 111. The column outlet at the upper end of the distillation column 10 is connected to the inlet of the top condenser 12 through a connecting pipeline. The outlet of the top condenser 12 is connected to the input terminal of a reflux ratio controller 13. The first output terminal of the reflux ratio controller 13 is connected to the second column inlet at the upper end of the distillation column 10 through a first branch 131. The second output terminal of the reflux ratio controller 13 is connected to the second tank inlet at the upper end of the phosphorus trichloride receiving tank 1 through a second branch 132. The reboiler 7 is provided with a material outlet at its lower side, and the material after distillation in the distillation column 10 is output from the material outlet. The material outlet is connected to the preheating tube inlet in the preheater 14 through the finished product output pipeline 16. The preheating tube outlet of the preheater 14 is connected to the finished product collection unit 3.

[0029] In operation, fresh phosphorus trichloride is preheated in preheater 14 via phosphorus trichloride feed pipe 15, and then enters phosphorus trichloride receiving tank 1 before entering reactor 5 to react with raw material oxygen supplied by oxygen feed pipe 4. The reaction liquid enters reboiler 7 via first circulation pipe 6 and returns to reactor 5 via second circulation pipe 9 to continue the oxidation reaction. Reboiler 7 is the main unit for recovering the heat of oxidation reaction. The reaction liquid, as a heat source, continuously provides heat to the distillation material through heat exchange tube 701 in reboiler 7. In addition, preheater 14 uses the heat of finished product to preheat raw phosphorus trichloride, which can also recover part of the reaction heat and simultaneously cool the finished product.

[0030] like Figures 2-3As shown, the jet swirl type pressure-stabilized condenser 8 includes a swirl condenser housing 803 and an ejector 801 and a cooling guide coil 802 disposed in the swirl condenser housing 803. The circulation branch 901 is provided with a pressure relief pipe, and the output end of the circulation branch 901 forms multiple branches that are respectively connected to the corresponding ejector 801. When the distillation system is running stably, the reaction liquid in the circulation branch 901 is depressurized and enters the jet cyclone stabilizing condenser 8. After being sprayed by the ejector 801, a mixture of the reaction liquid and oxygen dissolved in the reaction liquid is formed in the shell 803. The mixture continues to react with the oxygen released from the depressurization and phosphorus trichloride in the reaction liquid under the relatively low temperature conditions of the cooling guide coil 802. By adjusting the cooling water flow rate, the material close to the bubble point of the reaction liquid flows into the stabilizing tank 111 and then enters the distillation column 10 for continuous distillation. The top material in the distillation column 10 passes through the top condenser 12 and the reflux ratio controller 13 and the unreacted phosphorus trichloride is collected and sent to the phosphorus trichloride receiving tank 1. The material in the bottom reboiler 7 flows into the finished product collection unit 3 after passing through the preheater 14.

[0031] The reactor 5, distillation column 10, ejector 801, and reflux ratio controller 13 are all technologies known in the art and are commercially available products. In this embodiment, the reactor 5 is a liquid jet gas-liquid circulation reactor, with a reaction temperature of 80-180℃ and a reaction pressure (gauge pressure) of 0.05-1.0 MPa. The distillation column 10 is a packed column, a plate column, or a gravity distillation column, with an operating pressure of atmospheric or reduced pressure. The ejector 801 is a self-priming ejector, and the number of self-priming ejectors in the jet cyclone stabilizing condenser 8 is 1-2. The material jetting direction is offset downwards by 10-30° along the horizontal direction of the cyclone condenser shell 803, and the vertical diameter ratio of the cyclone condenser shell 803 is 1.05:1-5:1.

[0032] like Figure 1 As shown, a raw material flow meter 151 is installed on the phosphorus trichloride raw material input pipeline 151.

[0033] like Figure 1 As shown, a phosphorus trichloride conveying pump 201 and a phosphorus trichloride flow meter 202 are sequentially installed on the phosphorus trichloride conveying pipeline 2 along the material conveying direction.

[0034] like Figure 1 As shown, an oxygen flow meter 401 is installed on the oxygen input pipeline 4.

[0035] like Figure 1 As shown, a circulation pump 601 is provided on the first circulation pipeline 6.

[0036] like Figure 1As shown, a pressure stabilizing tank 111 and a material flow meter 112 are sequentially arranged along the material transmission direction on the material inlet pipeline 11.

[0037] like Figure 1 As shown, the finished product collection unit 3 includes a finished product conveying pump 301, a finished product flow meter 302, and a finished product tank 303 connected in series.

[0038] Each pipeline is equipped with a control valve to control the opening and closing of the pipeline, which is a well-known technology in this field.

[0039] The working principle of this invention is as follows:

[0040] Step 1: Add phosphorus trichloride to reactor 5 and phosphorus oxychloride to reboiler 7;

[0041] Step 2: Open the first circulation pipeline 6 and the oxygen input pipeline 4, and control the oxygen intake, pressure and temperature parameters of the reactor 5. At the same time, adjust the distillation column 10 to total reflux until the system is running stably.

[0042] Step 3: Turn on the jet cyclone stabilizing condenser 8 and the inlet material pipeline 11, and control the feed rate and feed temperature of the reaction liquid in the distillation column 10, while adjusting the reflux ratio of the reflux ratio controller 13;

[0043] Step 4: Open the connecting pipeline connected to the top condenser 12 and the finished product output pipeline 16 below the reboiler 7 to achieve continuous collection from the top and bottom of the distillation column 10. At the same time, open the phosphorus trichloride delivery pipeline 2 to continuously feed into the reactor 5 and control the phosphorus trichloride feed rate. The system starts to operate stably.

[0044] Step 5: After the system's feeding and discharging operations are stable, monitor the status of each part of the system and make timely fine adjustments.

[0045] The following example further illustrates this point.

[0046] Application Example 1

[0047] Step 1: Add 0.2 m³ of phosphorus trichloride substrate to reactor 5. 3 (Phosphorus trichloride 98.0% wt, phosphorus oxychloride 2.0% wt), add 0.7 m³ of phosphorus oxychloride bottom material to reboiler 7. 3 (Phosphorus trichloride 0.2% wt, phosphorus oxychloride 99.8% wt).

[0048] Step 2: Turn on the circulation pump 601 on the first circulation pipeline 6, and turn on the oxygen input pipeline 4 to introduce oxygen into the reactor 5 to start the reaction, controlling the oxygen intake rate to 1.0-10.0 Nm³. 3 / h, the pressure of reactor 5 is controlled at 0.2-0.6Mpa, the temperature of reactor 5 is controlled at 120-160℃, and the distillation column 10 is adjusted to total reflux until the system is running stably.

[0049] Step 3: Turn on the jet cyclone condenser 8 and the inlet material pipeline 11, and control the feed rate of the reaction liquid in the distillation column 10 to be 0.01-5.0 m³. 3 The feed rate is set at 70-90℃, and the reflux ratio is adjusted to 1.5-10.0 by the reflux ratio controller 13.

[0050] Step 4: Open the connecting pipeline to the top condenser 12 and the finished product output pipeline 16 below the reboiler 7 to achieve continuous collection from the top and bottom of the distillation column 10. The top component (phosphorus trichloride 98.0% wt, phosphorus oxychloride 2.0% wt) is condensed and separated before returning to the phosphorus trichloride receiving tank 1. The bottom component (phosphorus trichloride 0.2% wt, phosphorus oxychloride 99.8% wt) first enters the preheater 14 via the finished product output pipeline 16 to preheat the phosphorus trichloride feedstock, and then is collected as product in the finished product collection unit 3. At the same time, start the phosphorus trichloride delivery pump 201 on the phosphorus trichloride delivery pipeline 2 to continuously feed phosphorus trichloride into the reactor 5, and control the phosphorus trichloride feed rate to 0.01-5.0 m³ / h. 3 / h, the continuous production system begins to operate stably.

[0051] Step 5: After the system's feeding and discharging operations are stable, the automatic control system monitors the liquid level, pressure, and temperature of each tank in real time. The system maintains stable liquid level by fine-tuning the feed flow rate, regulates the reaction system pressure by using oxygen, and fine-tunes the system temperature within the set range by using the jacket heat exchange system of reactor 5. The content of the extracted components is controlled by the reflux ratio. At the same time, the production capacity can be increased or decreased or the reaction can be terminated at any time as needed.

Claims

1. A continuous production system for phosphorus oxychloride, characterized in that: The system includes a preheater (14), a phosphorus trichloride receiving tank (1), a reactor (5), a reboiler (7), a distillation column (10), a column top condenser (12), a jet cyclone pressure stabilizing condenser (8), and multiple pipelines. The phosphorus trichloride feedstock input pipeline (15) is connected to the feedstock inlet of the preheater (14). The feedstock outlet of the preheater (14) is connected to the first tank inlet of the phosphorus trichloride receiving tank (1) via a feedstock transfer pipeline (17). The tank outlet of the phosphorus trichloride receiving tank (1) is connected to the first tank inlet of the reactor (5) via a phosphorus trichloride delivery pipeline (2). The reactor (5) is connected to a first reaction inlet, and the oxygen input pipeline (4) is connected to the second reaction inlet of the reactor (5). The material outlet of the reactor (5) is connected to the inlet of the heat exchange tube (701) in the reboiler (7) through the first circulation pipeline (6). The outlet of the heat exchange tube (701) in the reboiler (7) is connected to the third reaction inlet of the reactor (5) through the second circulation pipeline (9). The distillation column (10) is located on the upper side of the reboiler (7), and the interior of the distillation column (10) is connected to the interior of the reboiler (7). A circulation branch (901) is provided on the second circulation pipeline (9). The output port of the jet cyclone stabilizing condenser (8) is connected to the inlet of the distillation column (10) via the inlet material pipeline (11), and a pressure stabilizing tank (111) is provided on the inlet material pipeline (11). The outlet of the upper end of the distillation column (10) is connected to the inlet of the top condenser (12) via a connecting pipeline. The outlet of the top condenser (12) is connected to the input of a reflux ratio controller (13), and the first output of the reflux ratio controller (13) is connected via... The first branch (131) is connected to the second column inlet at the top of the distillation column (10). The second output end of the reflux ratio controller (13) is connected to the second tank inlet at the top of the phosphorus trichloride receiving tank (1) via the second branch (132). The reboiler (7) has a material outlet on its lower side. The material after distillation in the distillation column (10) is output from the material outlet. The material outlet is connected to the preheating tube inlet in the preheater (14) via the finished product output pipeline (16). The preheating tube outlet of the preheater (14) is connected to the finished product collection unit (3). The jet swirl-type pressure-stabilized condenser (8) includes a swirl condenser shell (803) and an ejector (801) and a cooling guide coil (802) disposed in the swirl condenser shell (803). The circulation branch (901) is provided with a pressure relief pipeline, and the output end of the circulation branch (901) forms multiple branches that are respectively connected to the corresponding ejector (801). The number of ejectors (801) in the jet vortex pressure stabilizing condenser (8) is 1-2. The material jetting flow direction is offset downward by 10-30° along the horizontal direction of the vortex condenser shell (803). The vertical diameter ratio of the vortex condenser shell (803) is 1.05:1-5:

1.

2. The continuous production system for phosphorus oxychloride according to claim 1, characterized in that: A raw material flow meter (151) is installed on the phosphorus trichloride raw material input pipeline (15).

3. The continuous production system for phosphorus oxychloride according to claim 1, characterized in that: The phosphorus trichloride conveying pipeline (2) is provided with a phosphorus trichloride conveying pump (201) and a phosphorus trichloride flow meter (202) in sequence along the material conveying direction.

4. The continuous production system for phosphorus oxychloride according to claim 1, characterized in that: An oxygen flow meter (401) is installed on the oxygen input pipeline (4).

5. The continuous production system for phosphorus oxychloride according to claim 1, characterized in that: A circulation pump (601) is provided on the first circulation pipeline (6).

6. The continuous production system for phosphorus oxychloride according to claim 1, characterized in that: The material inlet pipeline (11) is provided with a pressure stabilizing tank (111) and a material inlet flow meter (112) in sequence along the material transmission direction.

7. The continuous production system for phosphorus oxychloride according to claim 1, characterized in that: The finished product collection unit (3) includes a finished product conveying pump (301), a finished product flow meter (302), and a finished product tank (303) connected in series.

8. A method for continuous production system of phosphorus oxychloride according to claim 1, characterized in that: Includes the following steps: Step 1: Add phosphorus trichloride to the reactor (5) and phosphorus oxychloride to the reboiler (7); Step 2: Open the first circulation pipeline (6) and the oxygen input pipeline (4), and control the oxygen intake, pressure and temperature parameters of the reactor (5), while adjusting the distillation column (10) to full reflux until the system is running stably; Step 3: Turn on the jet cyclone stabilizing condenser (8) and the inlet material pipeline (11), and control the feed rate and feed temperature of the reaction liquid in the distillation column (10), while adjusting the reflux ratio controller (13) reflux ratio; Step 4: Open the connecting pipeline connected to the top condenser (12) and the finished product output pipeline (16) below the reboiler (7) to achieve continuous sampling from the top and bottom of the distillation column (10). At the same time, open the phosphorus trichloride delivery pipeline (2) to continuously feed the reactor (5) and control the phosphorus trichloride feed rate. The system starts to operate stably. Step 5: After the system's feeding and discharging operations are stable, monitor the status of each part of the system and make timely fine adjustments.

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