Phosphorous acid production method and centrifugal apparatus

Abstract

The application provides a phosphorous acid production method, which comprises the following steps: collecting a liquid phase after centrifugal separation, performing distillation and cooling crystallization again, and then performing centrifugal separation again, so that the loss amount of phosphorous acid is reduced, the yield of products can be improved, and the problem that the removal of liquid in the prior art causes the loss of part of phosphorous acid and low product yield is solved; and the application also provides a centrifugal device for centrifugal separation, which can conveniently centrifugate crystallized phosphorous acid, recover the liquid phase, perform distillation and cooling crystallization again, and then perform centrifugal separation again.

Description

Technical Field

[0001] This invention relates to the field of phosphorous acid production technology and equipment, and in particular to a phosphorous acid production method and centrifuge equipment. Background Technology

[0002] Phosphorous acid can be produced using the phosphorus trichloride process. Specifically, phosphorus trichloride is used as raw material, and an acid hydrolysis method is employed, followed by separation and purification. During production, hydrochloric acid is typically used for hydrolysis, producing byproducts such as hydrogen chloride gas and hydrochloric acid solution. The hydrogen chloride gas can be removed by water absorption, followed by distillation and cooling crystallization to obtain solid phosphorous acid. However, in actual production, the obtained solid phosphorous acid still requires centrifugation to remove the liquid. The removed liquid still contains some phosphorous acid, resulting in a low product yield. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a method for producing phosphorous acid, which solves the problem that the removal of liquid in existing technologies leads to the loss of some phosphorous acid, resulting in a low product yield.

[0004] According to an embodiment of the present invention, a method for producing phosphorous acid includes:

[0005] Hydrolysis: Phosphorus trichloride is hydrolyzed with hydrochloric acid to produce phosphorous acid solution, hydrogen chloride gas and hydrochloric acid solution. After the hydrogen chloride gas is extracted, it is absorbed by water to produce hydrochloric acid.

[0006] Distillation: The phosphorous acid solution and hydrochloric acid solution obtained from hydrolysis are subjected to negative pressure distillation.

[0007] Cooling and crystallization: The distillation residue is cooled and crystallized, then centrifuged. The liquid phase is distilled and cooled and crystallized again. The combined centrifuged solid components are the finished phosphorous acid product.

[0008] In the above embodiments, after centrifugation, the collected liquid phase is distilled and cooled for crystallization again, and then centrifuged again, which reduces the amount of phosphorous acid loss and improves the product yield. This solves the problem in the prior art that the removal of liquid leads to the loss of some phosphorous acid, resulting in a low product yield.

[0009] According to an embodiment of the present invention, a centrifuge apparatus for the above-described centrifugal separation is also provided, comprising:

[0010] The casing contains a centrifuge chamber. A drive motor is also installed on the casing, and the shaft of the drive motor is fixedly connected to a mounting column extending into the centrifuge chamber. An inlet and outlet are also provided on the top of the casing.

[0011] The outer cylinder is closed at the bottom and its center is engaged with the mounting column. The upper end of the outer cylinder is open and its upper outer wall slides in contact with the inner wall of the inlet and outlet.

[0012] The inner cylinder is closed at the bottom and snapped into the outer cylinder.

[0013] The inner top plate is snapped into and pressed against the outer cylinder.

[0014] The outer top cover is detachably connected to the housing and also slides against the outer cylinder and the inner top cover.

[0015] The feed cylinder is detachably connected to the outer top cover and passes through the outer top cover and the inner top plate in sequence to connect the inner cylinder body with the outside.

[0016] The casing is also fixedly connected to a drain pipe that connects the inside and outside of the centrifuge chamber. The outer cylinder and the inner cylinder are respectively provided with a first centrifuge hole and a second centrifuge hole. The outer cylinder is also surrounded by a cooling pipe located inside the centrifuge chamber. The two ends of the cooling pipe are fixedly extended to the outside of the casing to introduce and export the cooling medium. The casing is also fixedly connected to a gas supply pipe that communicates with the centrifuge chamber to guide inert gas.

[0017] Furthermore, an installation chamber is provided inside the casing, with the centrifuge chamber surrounding the installation chamber. The bottom outer edge of the centrifuge chamber is lower than the upper outer edge of the installation chamber. The upper end of the installation chamber is connected to the centrifuge chamber. The drive motor is installed inside the installation chamber, and the bottom of the outer cylinder is slidably fastened to the bottom of the centrifuge chamber.

[0018] Furthermore, a first sliding cylinder extends upward from the center of the centrifuge chamber, and a second sliding cylinder extends downward from the bottom of the outer cylinder. The inner wall of the second sliding cylinder slides in contact with the outer wall of the first sliding cylinder, and the mounting column is engaged with the inner top surface of the second sliding cylinder.

[0019] Furthermore, the inner bottom surface of the centrifuge chamber is provided with an inclined annular surface surrounding the first sliding cylinder and located below the first sliding cylinder, and the drain pipe is located at the lowest point of the inclined annular surface.

[0020] Furthermore, a locking block is fixedly connected to the inner bottom surface of the outer cylinder, and a locking groove is recessed on the outer bottom surface of the inner cylinder for the locking block to engage.

[0021] Furthermore, a pair of first limiting blocks are fixedly connected to the outer walls on both sides of the upper end of the inner cylinder, and a pair of first limiting notches are recessed on the inner walls on both sides of the upper end of the outer cylinder for the two first limiting blocks to abut against.

[0022] Furthermore, a support ring is fixedly connected to the upper inner wall of the outer cylinder, two first limiting notches are set on the support ring, and the inner top plate covers the support ring.

[0023] Furthermore, the inner top plate is also fixedly connected with a pair of second limiting blocks located on both sides, and the upper inner wall of the outer cylinder is also recessed with a pair of second limiting notches for the two second limiting blocks to abut against.

[0024] Furthermore, a first abutment ring and a second abutment ring are fixedly connected to the outer top cover and are arranged concentrically with the inlet and outlet. The first abutment ring slides in contact with the top surface of the outer cylinder, and the second abutment ring slides in contact with the inner top plate.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The method provided by this invention can reduce the loss of phosphorous acid, thereby improving the recovery rate of phosphorous acid and solving the problem that the removal of liquid in the prior art leads to the loss of some phosphorous acid, resulting in a low product yield. At the same time, it also provides a centrifugal device for centrifugal separation, which can conveniently centrifuge the crystallized phosphorous acid, then recover the liquid phase for redistillation and cooling crystallization, and then perform centrifugal separation again. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present invention;

[0028] Figure 2 for Figure 1 Enlarged schematic diagram of a local structure at point A;

[0029] In the above attached figures:

[0030] 1. Casing; 2. Centrifuge chamber; 3. Drive motor; 4. Mounting column; 5. Inlet / outlet; 6. Outer cylinder; 7. Inner cylinder; 8. Inner top plate; 9. Outer top cover; 10. Bolt; 11. Feed cylinder; 12. Drain pipe; 13. First centrifuge hole; 14. Second centrifuge hole; 15. Cooling pipe; 16. Sealing cap; 17. Outlet pipe; 18. Air supply pipe; 19. Mounting chamber; 20. First sliding cylinder; 21. Second sliding cylinder; 22. Inclined annular surface; 23. Locking block; 24. First limiting block; 25. Support ring; 26. Second limiting block; 27. First abutment ring; 28. Second abutment ring. Detailed Implementation

[0031] The technical solutions of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0032] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0033] In an exemplary implementation, such as Figure 1 , 2 As shown, this embodiment provides a centrifuge device, which includes:

[0034] The casing 1 has a centrifuge chamber 2 inside it. A drive motor 3 is also installed on the casing 1, and the shaft of the drive motor 3 is fixedly connected to a mounting column 4 that extends into the centrifuge chamber 2. An inlet and outlet 5 are also provided on the top of the casing 1.

[0035] The outer cylinder 6 is closed at the bottom and its center is engaged with the mounting column 4. The upper end of the outer cylinder 6 is open and its upper outer wall is in sliding contact with the inner wall of the inlet and outlet 5.

[0036] Inner cylinder 7, the bottom of the inner cylinder 7 is closed and snapped into the outer cylinder 6;

[0037] The inner top plate 8 is snapped into and pressed against the outer cylinder 6;

[0038] The outer top cover 9 is detachably connected to the casing 1 and also slides against the outer cylinder 6 and the inner top cover. The outer top cover 9 can be fixed to the casing 1 by bolts 10, which is also easy to disassemble. Then the inner cylinder 7 is taken out, and then the solids after centrifugation are taken out.

[0039] The feed cylinder 11 is detachably connected to the outer top cover 9 and passes through the outer top cover 9 and the inner top plate 8 in sequence to connect the inner cylinder 7 with the outside. The feed cylinder 11 is used to introduce the material to be centrifuged (i.e., the solid that is cooled and crystallized). In this way, the material can be added without opening the outer top cover 9, which is convenient for multiple feedings without having to open the outer top cover 9 each time.

[0040] The casing 1 is also fixedly connected to a drain pipe 12 that connects the inside and outside of the centrifuge chamber 2. The outer cylinder 6 and the inner cylinder 7 are respectively provided with a first centrifuge hole 13 and a second centrifuge hole 14. The outer cylinder 6 is also surrounded by a cooling pipe 15 located inside the centrifuge chamber 2. The two ends of the cooling pipe 15 are respectively fixedly extended to the outside of the casing 1 to introduce and export the cooling medium. The casing 1 is also fixedly connected to a gas supply pipe 18 that communicates with the centrifuge chamber 2 to guide inert gas. The gas supply pipe 18 is located at the highest point of the centrifuge chamber 2, so that liquid is not easy to enter.

[0041] Specifically, the introduced inert gas can be nitrogen, and the coolant can be a coolant cooled by an external cooler. After entering the cooling pipe 15, the introduced inert gas can be cooled in the centrifuge chamber 2. The cooled inert gas can pass through the second centrifuge hole 14 and the first centrifuge hole 13, so that the centrifuge chamber 2, the outer cylinder 6, and the inner cylinder 7 are all in a low-temperature environment, so that centrifugal separation is carried out at a low temperature. Furthermore, the upper end of the feed cylinder 11 is also threaded with a cover 16, and an outlet pipe 17 is fixedly connected to the cover 16. An induced draft fan can also be installed at the outlet pipe 17 to guide the airflow in the inner cylinder 7, so that the inert gas introduced from the gas supply pipe 18 can efficiently pass through the second centrifuge hole 14 and the first centrifuge hole 13, and then enter the feed cylinder 11 and the outlet pipe 17 for discharge. The outlet pipe 17 and the induced draft fan can be detachably connected without affecting the opening and closing of the cover 16, which facilitates feeding.

[0042] In another exemplary embodiment, a method for producing phosphorous acid using the above-described centrifugal apparatus is also provided, comprising:

[0043] Hydrolysis: Phosphorus trichloride is hydrolyzed with hydrochloric acid to produce phosphorous acid solution, hydrogen chloride gas and hydrochloric acid solution. After the hydrogen chloride gas is extracted, it is absorbed by water to produce hydrochloric acid.

[0044] Distillation: The phosphorous acid solution and hydrochloric acid solution obtained from hydrolysis are subjected to negative pressure distillation.

[0045] Cooling and crystallization: The distillation residue is cooled and crystallized, then centrifuged. The liquid phase is distilled and cooled and crystallized again. The combined centrifuged solid components are the finished phosphorous acid product.

[0046] In the above embodiments, after centrifugation, the collected liquid phase is distilled and cooled for crystallization again, and then centrifuged again. This reduces the amount of phosphorous acid loss, thereby improving the product yield and solving the problem in the prior art where removing liquid leads to the loss of some phosphorous acid, resulting in a low product yield. Specifically, in this solution, phosphorous acid crystallization can be smoothly introduced multiple times, and the liquid can be discharged through the drain pipe 12 and then sent to the previous step for distillation and cooling for crystallization, which facilitates multiple cycles of operation before unified product recovery.

[0047] In more detail, the casing 1 also includes an installation chamber 19, with a centrifugal chamber 2 surrounding the installation chamber 19. The bottom outer edge of the centrifugal chamber 2 is lower than the upper outer edge of the installation chamber 19. The upper end of the installation chamber 19 is connected to the centrifugal chamber 2. The drive motor 3 is installed inside the installation chamber 19. The bottom of the outer cylinder 6 is slidably fastened to the bottom of the centrifugal chamber 2. The drive motor 3 drives the outer cylinder 6 to rotate via the mounting column 4. The outer cylinder 6 and the inner cylinder 7 are interlocked and can rotate together, thus achieving synchronous rotation of the inner and outer cylinders to centrifuge the material. The material is fed into the inner cylinder 7. During centrifugation, the cooled inert gas cools the centrifugal environment without reacting with the material. Specifically, the diameter of the first centrifugal hole 13 is... The material is smaller than the second centrifuge hole 14. The second centrifuge hole 14 has a smaller obstruction effect on the material (the material can pass smoothly through the second centrifuge hole 14 along with the liquid under centrifugation). In the initial stage of centrifugation (a period of time after the equipment is started), some material will pass through the second centrifuge hole 14 with the liquid to the outer cylinder 6, and then be intercepted in the outer cylinder 6. Most of the solid product after centrifugation will remain in the outer cylinder 6, while the inner cylinder 7 is used for the next round of material addition. For example, in the above embodiment, the liquid from the previous centrifugation is distilled again, cooled and crystallized, and then centrifuged again. That is, it can be centrifuged again after being added, and then the outer top cover 9 can be opened at the same time to take out the inner top plate 8 and the inner cylinder 7. The outer cylinder can also be taken out to remove the product together.

[0048] Furthermore, both the inner cylinder 7 and the outer cylinder 6 are inverted frustum shapes, smaller at the bottom and larger at the top. This allows the inclined inner wall to guide the liquid upwards along the inner wall during centrifugation. As it moves upwards, it gradually passes through the second centrifugation hole 14 and the first centrifugation hole 13. In particular, the lower end of the outer cylinder 6 does not have the first centrifugation hole 13. This prevents the material initially entering the outer cylinder 6 from entering the first centrifugation hole 13 and causing blockage. It also does not obstruct the smooth discharge of the liquid (the liquid can move upwards along the inclined inner wall and pass through the first centrifugation hole 13 into the external centrifugation chamber 2, and then be discharged through the drain pipe 12 at the bottom).

[0049] More specifically, a first sliding cylinder 20 extends upward from the center of the centrifuge chamber 2, and a second sliding cylinder 21 extends downward from the bottom of the outer cylinder 6. The inner wall of the second sliding cylinder 21 slides in contact with the outer wall of the first sliding cylinder 20. The mounting post 4 engages with the inner top surface of the second sliding cylinder 21 (the inner top surface of the second sliding cylinder 21 has a polygonal groove, and the mounting post 4 is a polygonal structure that matches it. After the two are engaged, the drive motor 3 can drive the outer cylinder 6 to rotate, and the outer cylinder 6 can also be lifted upward to remove it from the casing 1, facilitating the complete removal of the product). The first sliding cylinder 20 and the second sliding cylinder 21... The two sliding cylinders 21 enable the lower end of the outer cylinder 6 to rotate more stably under their rotational guidance, resulting in smoother operation. Furthermore, the inner bottom surface of the centrifuge chamber 2 is provided with an inclined annular surface 22 surrounding the first sliding cylinder 20 and located below the first sliding cylinder 20. The drain pipe 12 is located at the lowest point of the inclined annular surface 22. The inclined annular surface 22 causes the liquid to accumulate at the lower outer edge, thereby preventing the liquid from passing between the first sliding cylinder 20 and the second sliding cylinder 21 and causing adverse effects on the installation chamber 19. At the same time, the drain pipe 12 is located at the lowest point, so that the liquid can be easily discharged.

[0050] More specifically, a locking block 23 is fixedly connected to the inner bottom surface of the outer cylinder 6, and a locking groove is recessed on the outer bottom surface of the inner cylinder 7 for the locking block 23 to engage. Specifically, the locking block 23 and the locking groove are mutually cooperating polygons, which allows the inner cylinder 7 and the outer cylinder 6 to rotate together, thus rotating together under the drive of the drive motor 3, enabling smooth centrifugation. At the same time, the inner cylinder 7 can also be easily lifted upwards to separate from the outer cylinder 6, making it convenient to remove the product inside the outer cylinder 6. More specifically, this design also makes the inner top surface of the inner cylinder 7 higher than the inner bottom surface of the outer cylinder 6. After the liquid enters the outer cylinder 6, more of the material mixed in will fall to the bottom of the outer cylinder 6, while the liquid passes through the first centrifugation hole 13. Furthermore, the inner bottom surface of the inner cylinder 7 can also be an upwardly convex arc shape, which makes it easier for the material to move outwards during centrifugation, thus passing through the second centrifugation hole 14 more smoothly.

[0051] Furthermore, in this design, an outer top cover 9 is provided at the bottom of the outer cylinder 6 and the inner cylinder 7 to limit them and prevent them from accidentally moving out of the casing 1 during operation. A pair of first limiting blocks 24 are fixedly connected to the outer walls on both sides of the upper end of the inner cylinder 7. A pair of first limiting notches are recessed on the inner walls on both sides of the upper end of the outer cylinder 6 for the two first limiting blocks 24 to abut. The first limiting blocks 24 and the first limiting notches are symmetrically arranged, so as not to cause imbalance at the upper ends of the outer cylinder 6 and the inner cylinder 7. At the same time, this prevents relative rotation between the upper ends of the outer cylinder 6 and the inner cylinder 7, thus making the entire equipment run more smoothly together with the card block 23 and the card slot provided below.

[0052] Furthermore, a support ring 25 is fixedly connected to the upper inner wall of the outer cylinder 6, and two first limiting notches are provided on the support ring 25. The inner top plate 8 covers the support ring 25, and the inner top plate 8 presses down on the first limiting block 24, as well as the inner cylinder 7 and the outer cylinder 6, so that they do not move upward, thus allowing for more stable rotation. Similarly, a pair of second limiting blocks 26 located on both sides of the inner top plate 8 are also fixedly connected. A pair of second limiting notches are also recessed on the upper inner wall of the outer cylinder 6 for the two second limiting blocks 26 to abut against. This is consistent with the inner top plate 8. It does not rotate relative to the outer cylinder 6, and the second limiting block 26 and the second limiting notch are also symmetrically arranged, so as not to affect the stability of the overall equipment. Furthermore, the supporting ring 25 extends into the outer cylinder 6, thus providing a locking base for the upper end of the inner cylinder 7 (the locking between the first limiting block 24 and the first limiting notch), and also blocking the upper end of the inclined inner wall of the outer cylinder 6, preventing the liquid that is moving upward with the inclined inner wall from continuing to move upward, thereby forcing all the liquid at the highest point to pass through the first centrifuge hole 13 and leave.

[0053] Furthermore, the outer top cover 9 is also fixedly connected with a first abutment ring 27 and a second abutment ring 28, which are concentric with the inlet and outlet 5. The first abutment ring 27 slides in contact with the top surface of the outer cylinder 6, and the second abutment ring 28 slides in contact with the inner top plate 8. Specifically, the outer top cover 9 slides against the outer cylinder 6 and the inner top plate 8 through the first abutment ring 27 and the second abutment ring 28, respectively. This restricts the vertical displacement of the outer cylinder 6 and the inner cylinder 7, and does not hinder their rotation. More specifically, the top surface of the outer cylinder 6 and the top surface of the inner top plate 8 are respectively recessed with a first annular groove and a second annular groove with an arc cross section. The lower ends of the first abutment ring 27 and the second abutment ring 28 are arc-shaped and slide into the first annular groove and the second annular groove, respectively. This makes the sliding contact between the first abutment ring 27 and the second abutment ring 28 and the outer cylinder 6 and the inner top plate 8 relatively more stable.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A centrifuge device, characterized in that, include: The casing contains a centrifuge chamber, and a drive motor is mounted on the casing. The shaft of the drive motor is fixedly connected to a mounting column extending into the centrifuge chamber. An inlet and outlet are also provided on the top of the casing. The outer cylinder has a closed bottom and its center is engaged with the mounting post, while the upper end of the outer cylinder is open and its outer wall slides in contact with the inner wall of the inlet and outlet. An inner cylinder, the bottom of which is closed and snapped into the outer cylinder; An inner top plate, which is snapped into and pressed against the outer cylinder; The outer top cover is detachably connected to the housing and also slides against the outer cylinder and the inner top plate; The feed cylinder is detachably connected to the outer top cover and passes through the outer top cover and the inner top plate in sequence to connect the inner cylinder body with the outside; The casing is also fixedly connected to a drain pipe that connects the inside and outside of the centrifuge chamber. The outer cylinder and the inner cylinder are respectively provided with a first centrifuge hole and a second centrifuge hole. A cooling pipe located inside the centrifuge chamber is also arranged around the outer cylinder. The two ends of the cooling pipe are respectively fixedly extended to the outside of the casing to introduce and export the cooling medium. A gas supply pipe communicating with the centrifuge chamber is also fixedly connected to the casing to guide inert gas. The casing is further provided with an installation chamber, the centrifugal chamber surrounds the installation chamber, and the bottom outer edge of the centrifugal chamber is lower than the upper outer edge of the installation chamber. The upper end of the installation chamber is connected to the centrifugal chamber. The drive motor is installed in the installation chamber, and the bottom of the outer cylinder is slidably fastened to the bottom of the centrifugal chamber.

2. The centrifuge device as described in claim 1, characterized in that, A first sliding cylinder extends upward from the center of the centrifuge chamber, and a second sliding cylinder extends downward from the bottom of the outer cylinder. The inner wall of the second sliding cylinder slides in contact with the outer wall of the first sliding cylinder, and the mounting column is engaged with the inner top surface of the second sliding cylinder.

3. The centrifuge device as described in claim 2, characterized in that, The inner bottom surface of the centrifuge chamber is provided with an inclined annular surface that surrounds the first sliding cylinder and is located below the first sliding cylinder, and the drain pipe is located at the lowest point of the inclined annular surface.

4. The centrifuge device as described in claim 1, characterized in that, A locking block is fixedly connected to the inner bottom surface of the outer cylinder, and a locking groove is recessed on the outer bottom surface of the inner cylinder for the locking block to be engaged.

5. The centrifuge apparatus as described in claim 4, characterized in that, A pair of first limiting blocks are fixedly connected to the outer walls on both sides of the upper end of the inner cylinder, and a pair of first limiting notches are recessed on the inner walls on both sides of the upper end of the outer cylinder for the two first limiting blocks to abut against.

6. The centrifuge apparatus as described in claim 5, characterized in that, A support ring is fixedly connected to the upper inner wall of the outer cylinder, and two first limiting notches are provided on the support ring. The inner top plate covers the support ring.

7. The centrifuge apparatus as described in claim 6, characterized in that, The inner top plate is also fixedly connected to a pair of second limiting blocks located on both sides thereon, and the upper inner wall of the outer cylinder is also recessed with a pair of second limiting notches for the two second limiting blocks to abut against.

8. The centrifuge apparatus according to any one of claims 1-7, characterized in that, The outer top cover is also fixedly connected with a first abutment ring and a second abutment ring, which are concentric with the inlet and outlet. The first abutment ring slides in contact with the top surface of the outer cylinder, and the second abutment ring slides in contact with the inner top plate.

Images