A solid-liquid separation device and method for oxamide slurry

Abstract

The application discloses a kind of oxamide slurry solid-liquid separation device and method, belong to solid-liquid separation equipment technical field.A kind of oxamide slurry solid-liquid separation device, including sequentially communicating pre-separator, slurry tank, drum filter, filtrate tank;Pre-separator includes the first inlet for oxamide slurry to enter, the first outlet for small particle size oxamide slurry to flow out, the second outlet for large particle size oxamide slurry to flow out;Slurry tank includes large particle size oxamide slurry area and small particle size oxamide slurry area, small particle size oxamide slurry area is communicated with the first outlet, and large particle size oxamide slurry area is communicated with the second outlet;Filtrate tank is communicated with the outlet of drum filter.The device can solve the existing oxamide slurry solid-liquid separation slow, the problem of low oxamide wet material solid content.

Description

Technical Field

[0001] This invention relates to the field of solid-liquid separation equipment technology, and more specifically, to a solid-liquid separation device and method for oxalamide slurry. Background Technology

[0002] Oxalide is a novel slow-release nitrogen fertilizer characterized by high nitrogen utilization, low leaching loss, no environmental pollution, and the ability of plants to utilize its carbon. Oxalide is typically prepared by ammonolysis in methanol using ammonia and DMO as raw materials to form an oxamide slurry. This slurry undergoes solid-liquid separation, washing, and drying to yield the final oxamide product. Because the ammonolysis process for forming the oxamide slurry involves a reaction crystallization process, the particle size distribution of oxamide in the slurry is very wide. The solid-liquid separation process suffers from slow separation speed and low wet solids content of oxamide; existing technologies do not disclose this problem or provide corresponding solutions. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a solid-liquid separation device and method for oxamide slurry. The device of this invention uses a pre-separator to initially classify oxamide slurry of different particle sizes, and then feeds them separately into corresponding slurry zones for filtration through a rotary drum filter. This avoids the problem of small particles clogging the filter pores when materials of different particle sizes are mixed during filtration, effectively improving the filtration speed while ensuring the solid content of the filtered wet material. This solves the current problems of slow solid-liquid separation speed and low solid content of oxamide wet material in oxamide slurry.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A first aspect of the present invention provides a solid-liquid separation device for oxalamide slurry, the device comprising a pre-separator, a slurry tank, a rotary drum filter, and a filtrate tank connected in sequence.

[0006] The pre-separator includes a first inlet for oxamide slurry to enter, a first outlet for small-particle-size oxamide slurry to flow out, and a second outlet for large-particle-size oxamide slurry to flow out.

[0007] The slurry tank includes a large-particle-size oxalamide slurry zone and a small-particle-size oxalamide slurry zone. The small-particle-size oxalamide slurry zone is connected to the first outlet, and the large-particle-size oxalamide slurry zone is connected to the second outlet.

[0008] The filtrate tank is connected to the outlet of the rotary drum filter.

[0009] In some embodiments, the device further includes one or more of the following conditions:

[0010] A) The pre-separator includes a cylindrical body, which includes a first cylinder and a second cylinder. Both the first cylinder and the second cylinder are cylindrical, and the second cylinder is located inside the first cylinder.

[0011] B) The inner surface of the slurry tank is provided with a separation plate for separating large-particle-size oxalamide slurry and small-particle-size oxalamide slurry;

[0012] C) The outer surface of the rotary drum filter is provided with a filter medium;

[0013] D) The rotary drum filter has a cleaning zone for cleaning the filter cake on the side away from the slurry tank;

[0014] E) The filtrate tank includes a second inlet for the filtrate formed by the drum filter to enter, and the second inlet is connected to the outlet of the drum filter.

[0015] In some embodiments, the device further includes one or more of the following conditions:

[0016] A1) The inner surface of the first cylinder and the outer surface of the second cylinder form an annular gap;

[0017] A2) The first cylinder and the second cylinder are coaxially arranged;

[0018] A3) The cylinder is also provided with an upper end cover for sealing the top of the cylinder and a lower end cover for sealing the bottom of the cylinder.

[0019] In some embodiments, the device further includes one or more of the following conditions:

[0020] A11) The first inlet is disposed on the first cylinder, and the first inlet is located along the circumferential tangent of the annular gap;

[0021] A12) The first inlet is located at the middle position of the first cylinder along the axial direction;

[0022] A13) The first outlet is located at the top of the first cylinder, and the first outlet is located along the circumferential tangent of the annular gap;

[0023] (A14) The second outlet is located at the bottom of the first cylinder, and the second outlet is located along the circumferential tangent of the annular gap.

[0024] In some embodiments, the device further includes one or more of the following conditions:

[0025] B1) The inner surface of the slurry tank is arc-shaped;

[0026] B2) Both the isolation plate and the slurry tank are rectangular parallelepipeds;

[0027] B3) The isolation plate is located between the large-particle-size oxalamide slurry zone and the small-particle-size oxalamide slurry zone;

[0028] C1) The drum filter described above is cylindrical;

[0029] C2) The filter medium is selected from filter cloth or filter screen.

[0030] In some embodiments, the device further includes one or more of the following conditions:

[0031] B11) The side of the isolation plate away from the drum filter is adapted to the inner surface of the slurry tank, and the side of the isolation plate away from the slurry tank is adapted to the circumferential side profile of the drum filter.

[0032] B21) The length direction of the isolation plate is parallel to the length direction of the slurry tank, and the width direction of the isolation plate is parallel to the width direction of the slurry tank;

[0033] C11) The central axis of the drum filter is parallel to the length direction of the separator plate.

[0034] In some embodiments, the distance H between the side of the separator away from the slurry tank and the lowest point of the drum filter near the slurry tank satisfies: 1cm≤H≤10cm.

[0035] In some embodiments, the thickness of the large-particle-size oxalamide filter cake formed on the outer surface of the drum filter is R, wherein R and H satisfy: HR = 0.5~1.0 cm, and H ≥ R.

[0036] A second aspect of the present invention provides a method for solid-liquid separation of oxalamide slurry, comprising the following steps:

[0037] 1) The oxamide slurry to be separated is introduced into the pre-separator through the first inlet. Under the action of centrifugal force, the small-particle-size oxamide slurry enters the small-particle-size oxamide slurry zone through the first outlet, and the large-particle-size oxamide slurry enters the large-particle-size oxamide slurry zone through the second outlet.

[0038] 2) Control the drum filter to first immerse itself in the large-particle-size oxalamide slurry zone during rotation, forming a large-particle-size oxalamide slurry filter cake on the outer surface of the drum filter; then rotate the drum filter to immerse itself in the small-particle-size oxalamide slurry zone, forming a small-particle-size oxalamide slurry filter cake on the outer surface of the large-particle-size oxalamide slurry filter cake.

[0039] 3) The filtrate formed by the rotary drum filter enters the filtrate tank from the outlet, thus realizing the solid-liquid separation of the oxalamide slurry.

[0040] In some embodiments, in step (1), the D50 of the large-particle-size oxalamide slurry is ≥45μm; the particle size D50 of the small-particle-size oxalamide slurry is <45μm.

[0041] And / or, in step (2), the liquid level of the large-particle-size oxalamide slurry zone and the liquid level of the small-particle-size oxalamide slurry zone are at the same height;

[0042] And / or, in step (2), the internal and external pressure difference of the drum filter during the filtration process is 0.03~1.0 MPa.

[0043] The beneficial effects of this invention are as follows:

[0044] When the oxamide slurry undergoes solid-liquid separation, it first enters the pre-separator through the first inlet, where it is coarsely separated into large-particle-size oxamide slurry and small-particle-size oxamide slurry under centrifugal force. The large-particle-size oxamide slurry is then conveyed to the large-particle-size oxamide slurry zone of the slurry tank, and the small-particle-size oxamide slurry is conveyed to the small-particle-size oxamide slurry zone. During the rotary drum filter's rotational filtration process, the outer surface of the filter medium is first immersed in the large-particle-size oxamide slurry zone, where large-particle-size oxamide adheres to the outer surface under pressure differential. Then, the drum filter rotates to the small-particle-size oxamide slurry zone, where a layer of small-particle-size oxamide continues to adhere to the outer surface of the large-particle-size oxamide, forming a filter cake primarily composed of large-particle-size oxamide near the outer surface of the filter medium, and primarily composed of small-particle-size oxamide further away from the outer surface. Simultaneously, the filtrate formed by the rotary drum filter enters the filtrate tank. Because the oxamide filter cake has a certain degree of compressibility, this method avoids the problem of small-diameter oxamide clogging the micropores of the filter medium, and also avoids the problem of oxamide near the filter medium being compacted by pressure difference. This improves the solid-liquid separation speed, increases the solid content of the oxamide wet material, and further reduces the time and energy consumption for subsequent oxamide wet material drying. Attached Figure Description

[0045] The embodiments of this invention are not limited to the drawings described below, which are only some embodiments of this invention. Those skilled in the art can obtain drawings of other embodiments based on the content of this invention.

[0046] Figure 1 This is a schematic diagram of the solid-liquid separation device described in this invention.

[0047] Figure 2 This is a front view of the pre-separator described in this invention.

[0048] Figure 3 This is a top view of the pre-separator described in this invention.

[0049] Figure 4This is a cross-sectional view of surface AA in the top view of the pre-separator described in this invention.

[0050] Figures 1-4 middle:

[0051] 1. Pre-separator; 11. First cylinder; 12. Second cylinder; 13. Annular gap; 14. First inlet; 15. First outlet; 16. Second outlet; 17. Upper end cover; 18. Lower end cover;

[0052] 2. Slurry tank; 21. Large particle size oxalamide slurry zone; 22. Small particle size oxalamide slurry zone;

[0053] 3. Rotary drum filter; 31. Large-particle-size oxalamide slurry filter cake; 32. Small-particle-size oxalamide slurry filter cake; 33. Washing area;

[0054] 4. Filtration tank; 41. Second inlet;

[0055] 5. Isolation plate. Detailed Implementation

[0056] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0057] In this invention, the technical features described in an open-ended manner include both closed-ended technical solutions composed of the listed features and open-ended technical solutions that include the listed features.

[0058] In this invention, numerical ranges are involved. Unless otherwise specified, the numerical ranges are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe features or characteristics, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are included.

[0059] The terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., 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 application 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 application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0060] Furthermore, in the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0061] This invention provides a solid-liquid separation device for oxalamide slurry, such as... Figure 1 The device includes a pre-separator 1, a slurry tank 2, a rotary drum filter 3, and a filtrate tank connected in sequence.

[0062] like Figure 4 The pre-separator 1 includes a first inlet 14 for oxamide slurry to enter, a first outlet 15 for small-particle-size oxamide slurry to flow out, and a second outlet 16 for large-particle-size oxamide slurry to flow out.

[0063] like Figure 1 and Figure 4 The slurry tank 2 includes a large-particle-size oxalamide slurry zone 21 and a small-particle-size oxalamide slurry zone 22. The small-particle-size oxalamide slurry zone 22 is connected to the first outlet 15, and the large-particle-size oxalamide slurry zone 21 is connected to the second outlet 16.

[0064] like Figure 1 The filtrate tank 4 is connected to the outlet of the drum filter 3.

[0065] In some implementations, such as Figure 4 The pre-separator 1 includes a cylindrical body, which includes a first cylindrical body 11 and a second cylindrical body 12. Both the first cylindrical body 11 and the second cylindrical body 12 are cylindrical. The second cylindrical body 12 is located inside the first cylindrical body 11. The inner diameter of the first cylindrical body 11 is larger than the outer diameter of the second cylindrical body 12.

[0066] In some implementations, such as Figure 4 The inner surface of the first cylinder 11 and the outer surface of the second cylinder 12 form an annular gap 13.

[0067] In some implementations, such as Figure 4 The first cylinder 11 and the second cylinder 12 are coaxially arranged.

[0068] In some implementations, such as Figure 4 The first inlet 14 is disposed on the first cylinder 11, and the first inlet 14 is located in the circumferential tangential direction of the annular gap 13.

[0069] In some implementations, such as Figure 3 and Figure 4 The first inlet 14 is located at the middle position of the first cylinder 11 along the axial direction.

[0070] In some implementations, such as Figure 4 The first outlet 15 is located at the top of the first cylinder 11, and the first outlet 15 is located in the circumferential tangential direction of the annular gap 13.

[0071] In some implementations, such as Figure 4 The second outlet 16 is located at the bottom of the first cylinder 11, and the second outlet 16 is located along the circumferential tangent direction of the annular gap 13.

[0072] In some implementations, such as Figure 4 The cylinder is also provided with an upper end cap 17 for sealing the top of the cylinder and a lower end cap 18 for sealing the bottom of the cylinder.

[0073] In some implementations, such as Figure 1 The inner surface of the slurry tank 2 is provided with a separation plate 5 for separating large-particle-size oxalamide slurry and small-particle-size oxalamide slurry.

[0074] In some implementations, such as Figure 1 The inner surface of the slurry tank 2 is arc-shaped.

[0075] In some implementations, such as Figure 1 The inner surface of the slurry tank 2 is adapted to the outer surface of the drum filter 3.

[0076] In some implementations, such as Figure 1 The side of the separator 5 away from the drum filter 3 is adapted to the inner surface of the slurry tank 2, and the side of the separator 5 away from the slurry tank 2 is adapted to the circumferential side profile of the drum filter 3. This allows the slurry in the large-particle-size area and the small-particle-size area to be separated during the rotation of the drum filter 3, preventing the slurry in the two areas from flowing into each other and ensuring the stable formation of the filter cake layer structure.

[0077] In some implementations, such as Figure 1 Both the isolation plate 5 and the slurry tank 2 are rectangular parallelepipeds.

[0078] In some implementations, such as Figure 1 The length direction of the isolation plate 5 is parallel to the length direction of the slurry tank 2, and the width direction of the isolation plate 5 is parallel to the width direction of the slurry tank 2.

[0079] In some implementations, such as Figure 1 The isolation plate 5 is located between the large-particle-size oxalamide slurry zone 21 and the small-particle-size oxalamide slurry zone 22.

[0080] In some implementations, such as Figure 1 The outer surface of the drum filter 3 is provided with a filter medium.

[0081] In some implementations, such as Figure 1 The drum filter 3 is cylindrical.

[0082] In some implementations, such as Figure 1 The central axis of the drum filter 3 is parallel to the length direction of the isolation plate 5.

[0083] In some embodiments, the filter medium is selected from filter cloth or filter screen.

[0084] In some implementations, such as Figure 1 The distance H between the side of the isolation plate 5 away from the slurry tank 2 and the lowest point of the drum filter 3 near the slurry tank 2 is satisfied that 1cm≤H≤10cm, for example, it can be 1cm, 2cm, 3cm, 4cm, 5cm, 6cm, 7cm, 8cm, 9cm, 10cm or any combination of two of them.

[0085] The function of the separator 5 is to divide the slurry tank 2 into a large-particle-size oxalamide slurry zone 21 and a small-particle-size oxalamide slurry zone 22. The separator 5 cannot achieve complete isolation. Generally, the filter cake thickness formed by the rotary drum filter 3 filtering oxalamide slurry can reach 1~10 cm. Therefore, in this invention, the distance between the side of the separator 5 furthest from the slurry tank 2 and the lowest point of the rotary drum filter 3 closest to the slurry tank 2 is set to 1~10 cm.

[0086] In some implementations, such as Figure 1 The thickness of the large-particle-size oxalamide filter cake formed on the outer surface of the rotary drum filter 3 is R, and R and H satisfy: HR = 0.5~1.0 cm, and H ≥ R. For example, it can be a range of 0.5 cm, 0.6 cm, 0.7 cm, 0.8 cm, 0.9 cm, 1.0 cm, or any combination thereof.

[0087] In this invention, the distance between the side of the isolation plate 5 away from the slurry tank 2 and the lowest point of the drum filter 3 near the slurry tank 2 is 0.5 to 1.0 cm greater than the thickness of the large-particle-size oxalamide filter cake, but not less than the thickness of the large-particle-size oxalamide filter cake. This avoids the problem of the isolation plate 5 scraping off the already formed large-particle-size oxalamide filter cake, which would cause the filtration efficiency to drop sharply.

[0088] In some implementations, such as Figure 1 The drum filter 3 has a cleaning zone 33 for cleaning the filter cake on the side away from the slurry tank 2.

[0089] In some implementations, such as Figure 1 The filtrate tank 4 includes a second inlet 41 for the filtrate formed by the drum filter 3 to enter, and the second inlet 41 is connected to the outlet of the drum filter 3.

[0090] When the drum filter 3 and slurry tank 2 are operating under positive pressure, the filtrate can automatically enter the filtrate tank 4 by relying on the pressure difference. When the drum filter 3 and slurry tank 2 are operating under normal pressure, a vacuum needs to be drawn from the filtrate tank 4 so that the filtrate can smoothly enter the filtrate tank 4 from the drum filter 3 and provide a filtration pressure difference for the drum filter 3.

[0091] In some embodiments, the device further includes a cleaning conduit communicating with the cleaning zone 33.

[0092] This invention introduces a cleaning solvent into the cleaning zone 33 via a cleaning pipeline to wash the filter cake, thereby reducing the ammonia content and trace impurities in the filter cake. The invention achieves filter cake cleaning by spraying the cleaning solvent into the cleaning zone 33 of the rotary drum filter 3 through a cleaning pipeline. Since the solvent for oxalamide slurry is primarily methanol, this invention preferentially uses methanol as the cleaning solvent. Ethanol can also be used, but this increases the workload of subsequent separation.

[0093] A second aspect of the present invention provides a method for solid-liquid separation of oxalamide slurry, comprising the following steps:

[0094] 1) The oxamide slurry to be separated enters the pre-separator 1 through the first inlet 14. Under the action of centrifugal force, the small-particle-size oxamide slurry enters the small-particle-size oxamide slurry zone 22 through the first outlet 15, and the large-particle-size oxamide slurry enters the large-particle-size oxamide slurry zone 21 through the second outlet 16.

[0095] 2) Control the drum filter 3 to first immerse in the large particle size oxalamide slurry zone 21 during the rotation process, forming a large particle size oxalamide slurry filter cake 31 on the outer surface of the drum filter 3; then rotate the drum filter 3 to immerse in the small particle size oxalamide slurry zone 22, forming a small particle size oxalamide slurry filter cake 32 on the outer surface of the large particle size oxalamide slurry filter cake 31.

[0096] 3) The filtrate formed by the rotary drum filter 3 enters the filtrate tank 4 from the outlet, thus realizing the solid-liquid separation of the oxalamide slurry.

[0097] In the apparatus described in this invention, the oxamide slurry is first pre-separated into large-particle-size oxamide slurry and small-particle-size oxamide slurry. Then, the large-particle-size oxamide slurry is first immersed in the outer surface of the drum filter 3 to form a filter cake layer, followed by the small-particle-size oxamide slurry being immersed in the large-particle-size oxamide filter cake layer. After filter cake washing, a wet oxamide material is formed. The overall solid-liquid separation result is that the oxamide filter cake closer to the outer surface of the filter medium in the drum filter 3 has a larger particle size, while the oxamide filter cake farther from the outer surface of the filter medium in the drum filter 3 has a smaller particle size. This avoids the problems of the filter medium being easily clogged by small-particle-size oxamide and the filter cake near the filter medium being subjected to high external pressure, easily compressed, and having a long filtration time.

[0098] It should be noted that, because small-particle-size oxalamide can clog the pores of the filter medium in existing technologies, this invention only requires a certain thickness for the first layer of large-particle-size oxalamide filter cake formed on the outer surface of the filter medium, and does not have a particular requirement for the thickness of the filter cake formed subsequently. In this invention, the thickness of the large-particle-size oxalamide filter cake refers to the thickness of the first layer of filter cake formed on the outer surface of the filter medium.

[0099] In some embodiments, in step (1), the D50 of the large-particle-size oxalamide slurry is ≥45μm; and the particle size D50 of the small-particle-size oxalamide slurry is <45μm.

[0100] This invention defines the particle size of large-particle-size oxalamide slurry as D50≥45μm, and the particle size of small-particle-size oxalamide slurry as D50<45μm. This invention is based on the summary of experimental data on the particle size distribution of oxalamide prepared by ammonolysis using ammonia and DMO as raw materials, and also incorporates the pore size distribution of commonly used filter media.

[0101] In some embodiments, in step (2), the liquid level of the large-particle-size oxalamide slurry zone 21 and the liquid level of the small-particle-size oxalamide slurry zone 22 are at the same height.

[0102] When the liquid levels of the large-particle-size oxalamide slurry and the small-particle-size oxalamide slurry are kept at the same level, the adverse effects on the filtration process caused by the mixing of the large-particle-size oxalamide slurry and the small-particle-size oxalamide slurry, which allows the small-particle-size oxalamide slurry to enter the large-particle-size oxalamide slurry zone 21, can be minimized.

[0103] In some embodiments, in step (2), the internal and external pressure difference of the rotary drum filter 3 during the filtration process is 0.03~1.0 MPa, for example, it can be a range of 0.03MPa, 0.05MPa, 0.10MPa, 0.15MPa, 0.2MPa, 0.25MPa, 0.3MPa, 0.35MPa, 0.4MPa, 0.45MPa, 0.5MPa, 0.75MPa, 1.0MPa, or any combination thereof. This pressure difference is the maximum pressure difference that the filter cake layer bears during the filtration operation. Under this pressure difference condition, the entire device can be designed as positive pressure filtration or negative pressure filtration. Here, positive pressure filtration means that the pressure inside the filtrate tank 4 is greater than or equal to the ambient pressure, and negative pressure filtration means that the pressure inside the filtrate tank 4 is less than the ambient pressure.

[0104] In the following embodiments, unless otherwise specified, all the raw materials of the present invention are commercially available or prepared according to conventional methods in the art.

[0105] Example 1

[0106] This embodiment discloses a solid-liquid separation device for oxalamide slurry, referring to... Figure 1 The device includes a pre-separator 1, a slurry tank 2, a rotary drum filter 3, and a filtrate tank connected in sequence.

[0107] Reference Figure 1 and Figure 4 The pre-separator 1 includes a cylindrical body with a height of 45 cm. The cylindrical body comprises a first cylinder 11 and a second cylinder 12, both of which are tubular. The second cylinder 12 is located inside the first cylinder 11, and the first and second cylinders 11 and 12 are coaxially arranged. The inner diameter of the first cylinder 11 is 20 cm, and the outer diameter of the second cylinder 12 is 14 cm. An annular gap 13 is formed between the inner surface of the first cylinder 11 and the outer surface of the second cylinder 12 for the rotational separation of the oxalamide slurry.

[0108] Reference Figure 1 and Figure 2 The pre-separator 1 further includes a first inlet 14 for the entry of oxalamide slurry, the first inlet 14 having an inner diameter of 25 mm. The first inlet 14 is disposed on the first cylinder 11, and the first inlet 14 is located at the middle position of the cylinder along the axial direction.

[0109] Refer to 3 and Figure 4 The first inlet 14 is located in the circumferential tangential direction of the annular gap 13, so that the slurry enters the annular gap 13 along the inner wall of the first cylinder 11 and rotates along the outer wall of the second cylinder 12, thereby achieving the initial separation of oxamide slurry by means of centrifugal force.

[0110] Reference Figure 2 and Figure 3 The pre-separator 1 further includes a first outlet 15 for the outflow of small-particle-size oxalamide slurry and a second outlet 16 for the outflow of large-particle-size oxalamide slurry. The first outlet 15 is located at the top of the first cylinder 11 and is located along the circumferential tangent of the annular gap 13. The second outlet 16 is located at the bottom of the first cylinder 11 and is located along the circumferential tangent of the annular gap 13.

[0111] Reference Figure 3 and Figure 4 The first inlet 14 and the first outlet 15 are on the same horizontal line along the diameter of the cylinder. The first outlet 15 and the second outlet 16 are on the same vertical line along the central axis of the cylinder. The cylinder is also provided with an upper end cap 17 for sealing the top of the cylinder and a lower end cap 18 for sealing the bottom of the cylinder.

[0112] Reference Figure 1 and Figure 4 The slurry tank 2 is rectangular in shape, and its inner surface has a groove for holding the slurry, the groove being arc-shaped. The slurry tank 2 includes a large-particle-size oxalamide slurry zone 21 and a small-particle-size oxalamide slurry zone 22. The small-particle-size oxalamide slurry zone 22 is connected to the first outlet 15, and the large-particle-size oxalamide slurry zone 21 is connected to the second outlet 16. Under centrifugal force, the small-particle-size oxalamide slurry flows out from the first outlet 15, and the large-particle-size oxalamide slurry flows out from the second outlet 16, achieving initial separation of the oxalamide slurry.

[0113] Reference Figure 1 The rotary drum filter 3 is cylindrical, with a diameter of 0.4m and a length of 0.6m, and a rotation speed of 1.5r / min. In this embodiment, the rotary drum filter uses positive pressure filtration and rotates clockwise. The outer surface of the rotary drum filter 3 is provided with a filter medium, which in this embodiment is a filter cloth. The internal cavity of the rotary drum filter 3 is physically divided into multiple isolated chambers, each of which is controlled by valves to operate in filtration, washing, filtration drying, and unloading states.

[0114] Reference Figure 1The inner surface of the slurry tank 2 is provided with a separating plate 5 for separating large-particle-size oxalamide slurry and small-particle-size oxalamide slurry. The separating plate 5 is cuboid in shape, with its length parallel to the length of the slurry tank 2 and its width parallel to the width of the slurry tank 2. The inner surface of the slurry tank 2 is arc-shaped. The side of the separating plate 5 away from the drum filter 3 is adapted to the inner surface of the slurry tank 2, and the side of the separating plate 5 away from the slurry tank 2 is adapted to the circumferential side profile of the drum filter 3. This allows the slurry in the large-particle-size region and the small-particle-size region to be separated during the rotation of the drum body, preventing the slurry in the two regions from flowing into each other and ensuring the stable formation of the filter cake layered structure. The separating plate 5 is located between the large-particle-size oxalamide slurry region 21 and the small-particle-size oxalamide slurry region 22, and the length of the separating plate 5 is parallel to the central axis of the drum filter 3.

[0115] Reference Figure 1 The distance H between the side of the isolation plate 5 away from the slurry tank 2 and the lowest point of the drum filter 3 near the slurry tank 2 is 3.5 cm in this embodiment. The thickness R of the large-particle-size oxalamide filter cake 31 formed on the outer surface of the drum filter 3 is 3 cm. The liquid level of the large-particle-size oxalamide slurry zone 21 and the liquid level of the small-particle-size oxalamide slurry zone 22 are equal, which can minimize the adverse effects of small-particle-size oxalamide slurry entering the large-particle-size oxalamide slurry zone on the filtration process due to the mixing of large-particle-size and small-particle-size oxalamide slurry. The internal and external pressure difference of the drum filter 3 during the filtration process is 0.45 MPa. When the drum filter 3 and the slurry tank 2 are operating under positive pressure, the filtrate can automatically enter the filtrate tank by relying on the pressure difference.

[0116] Reference Figure 1 The filtrate tank 4 includes a second inlet 41 for the filtrate formed by the drum filter 3 to enter, and the second inlet 41 is connected to the outlet of the drum filter 3. The drum filter 3 also includes a cleaning zone 33 for cleaning the filter cake, and the cleaning zone 33 is located on the side of the drum filter 3 away from the slurry tank 2.

[0117] The solid-liquid separation device described in this embodiment also includes a cleaning pipeline to facilitate the cleaning of the formed oxalamide filter cake. The cleaning pipeline sprays cleaning solvent into the cleaning zone of the drum filter. Methanol is used as the cleaning solvent in this embodiment. Methanol washing flow rate: 800 kg / h.

[0118] This embodiment also discloses a solid-liquid separation method for oxamide slurry, comprising the following steps:

[0119] (1) The oxalamide slurry to be separated (Dv50=52.62μm, slurry solid content: 32.4wt%) is pumped into the annular gap 13 from the first inlet 14 along the inner wall of the first cylinder 11 using a slurry pump. The flow rate of the slurry pump is 13.5 m. 3 The oxamide slurry rotates around the outer wall of the second cylinder 12 under the action of the slurry pump, and then separates into small-particle-size oxamide slurry and large-particle-size oxamide slurry under centrifugal force. The large-particle-size oxamide slurry has a Dv50 of 66.3 μm; the small-particle-size oxamide slurry has a Dv50 of 41.45 μm. Then the small-particle-size oxamide slurry enters the small-particle-size oxamide slurry zone 22 from the first outlet 15, and the large-particle-size oxamide slurry enters the large-particle-size oxamide slurry zone 21 from the second outlet 16.

[0120] (2) Control the drum filter 3 to rotate clockwise. During the rotation, the filter medium in the drum filter 3 is first immersed in the large particle size oxalamide slurry zone 21. The large particle size oxalamide slurry adheres to the outer surface of the filter medium to form a large particle size oxalamide filter cake 31. Then the drum filter 3 is rotated to the immersion zone 22 of small particle size oxalamide slurry. The small particle size oxalamide slurry adheres to the outer surface of the large particle size oxalamide filter cake 31 to form a small particle size oxalamide filter cake 32.

[0121] (3) Then, the cleaning pipeline is opened to spray the cleaning solvent into the cleaning zone 33 of the drum filter 3. The small-diameter filter cake and the large-diameter filter cake are washed and dried to obtain oxamide wet material. The amount of oxamide wet material is about 3800 kg / h, and the solid content of oxamide wet material is 92.3 wt%. The filtrate formed by the drum filter 3 enters the filtrate tank 4 from the second inlet 41, thus realizing the solid-liquid separation of the oxamide slurry.

[0122] Comparative Example 1

[0123] The difference from Example 1 is that the solid-liquid separation device for the oxamide slurry does not include a pre-separator, and the slurry tank does not have a separator; that is, the oxamide slurry is discharged at a flow rate of 13.5 m... 3 The flow rate of / h is directly fed into the slurry tank for filtration.

[0124] After filtration of oxalamide slurry:

[0125] The wet feed rate of oxalamide is approximately 4100 kg / h.

[0126] Oxalide wet solids content: 86.4 wt%.

[0127] Comparing Comparative Example 1 with Example 1, it can be seen that the solid content of the oxamide wet material is reduced, indicating that small-particle-size oxamide adheres to the filter medium, causing the filtration to slow down and resulting in an increase in filtrate in the filter cake.

[0128] Comparative Example 2

[0129] The difference from Example 1 is that the solid-liquid separation device for the oxamide slurry does not include a pre-separator, and the slurry tank does not have a separator. The oxamide slurry is discharged at a rate of 10.5 m... 3 The flow rate of / h is directly fed into the slurry tank for filtration.

[0130] After filtration of oxalamide slurry:

[0131] Oxalide wet feed quantity: 2400 kg / h;

[0132] Oxalide wet solids content: 92.6 wt%.

[0133] Comparing Comparative Example 2 with Example 1, it can be seen that although the solid content of the oxalamide wet material in Comparative Example 2 is basically close to that in Example 1, the feed amount in Comparative Example 2 is reduced by about 20%, resulting in a decrease in filtration speed.

[0134] 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 the scope of protection of the present invention. 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 essence and scope of the technical solutions of the present invention.

Claims

1. A solid-liquid separation device for oxalamide slurry, characterized in that, The device includes a pre-separator (1), a slurry tank (2), a rotary drum filter (3), and a filtrate tank (4) connected in sequence. The pre-separator (1) includes a first inlet (14) for oxamide slurry entry, a first outlet (15) for small-particle-size oxamide slurry exit, and a second outlet (16) for large-particle-size oxamide slurry exit. The slurry tank (2) includes a large-particle-size oxalamide slurry zone (21) and a small-particle-size oxalamide slurry zone (22). The small-particle-size oxalamide slurry zone (22) is connected to the first outlet (15), and the large-particle-size oxalamide slurry zone (21) is connected to the second outlet (16). The filtrate tank (4) is connected to the outlet of the drum filter (3).

2. The solid-liquid separation device for oxalamide slurry according to claim 1, characterized in that, The device further includes one or more of the following conditions: A) The pre-separator (1) includes a cylindrical body, which includes a first cylindrical body (11) and a second cylindrical body (12). The first cylindrical body (11) and the second cylindrical body (12) are both cylindrical tubes, and the second cylindrical body (12) is located inside the first cylindrical body (11). B) The inner surface of the slurry tank (2) is provided with a separation plate (5) for separating large-particle-size oxalamide slurry and small-particle-size oxalamide slurry. C) The outer surface of the drum filter (3) is provided with a filter medium; D) The drum filter (3) has a cleaning zone (33) for cleaning the filter cake on the side away from the slurry tank (2). E) The filtrate tank (4) includes a second inlet (41) for the filtrate formed by the drum filter (3) to enter, and the second inlet (41) is connected to the outlet of the drum filter (3).

3. The solid-liquid separation device for oxalamide slurry according to claim 2, characterized in that, The device further includes one or more of the following conditions: A1) The inner surface of the first cylinder (11) and the outer surface of the second cylinder (12) form an annular gap (13). A2) The first cylinder (11) and the second cylinder (12) are coaxially arranged; A3) The cylinder is also provided with an upper end cap (17) for sealing the top of the cylinder and a lower end cap (18) for sealing the bottom of the cylinder.

4. The solid-liquid separation device for oxalamide slurry according to claim 3, characterized in that, The device further includes one or more of the following conditions: A11) The first inlet (14) is disposed on the first cylinder (11), and the first inlet (14) is located in the circumferential tangential direction of the annular gap (13); A12) The first inlet (14) is located at the middle position of the first cylinder (11) along the axial direction; A13) The first outlet (15) is located at the top of the first cylinder (11), and the first outlet (15) is located in the circumferential tangential direction of the annular gap (13). (A14) The second outlet (16) is located at the bottom of the first cylinder (11), and the second outlet (16) is located in the circumferential tangential direction of the annular gap (13).

5. The solid-liquid separation device for oxalamide slurry according to claim 2, characterized in that, The device further includes one or more of the following conditions: B1) The inner surface of the slurry tank (2) is arc-shaped; B2) Both the isolation plate (5) and the slurry tank (2) are rectangular parallelepipeds; B3) The isolation plate (5) is located between the large-particle-size oxalamide slurry zone (21) and the small-particle-size oxalamide slurry zone (22); C1) The drum filter (3) is cylindrical; C2) The filter medium is selected from filter cloth or filter screen.

6. The solid-liquid separation device for oxalamide slurry according to claim 5, characterized in that, The device further includes one or more of the following conditions: B11) The side of the isolation plate (5) away from the drum filter (3) is adapted to the inner surface of the slurry tank (2), and the side of the isolation plate (5) away from the slurry tank (2) is adapted to the circumferential side profile of the drum filter (3). B21) The length direction of the isolation plate (5) is parallel to the length direction of the slurry tank (2), and the width direction of the isolation plate (5) is parallel to the width direction of the slurry tank (2); C11) The central axis of the drum filter (3) is parallel to the length direction of the isolation plate (5).

7. The solid-liquid separation device for oxalamide slurry according to claim 2, characterized in that, The distance between the side of the isolation plate (5) away from the slurry tank (2) and the lowest point of the drum filter (3) near the slurry tank (2) is H, where H satisfies: 1cm≤H≤10cm.

8. The solid-liquid separation device for oxalamide slurry according to claim 7, characterized in that, The thickness of the large-particle-size oxalamide filter cake (31) formed on the outer surface of the drum filter (3) is R, and R and H satisfy: HR=0.5~1.0 cm, and H≥R.

9. A method for solid-liquid separation of oxalamide slurry, characterized in that, Includes the following steps: 1) The oxamide slurry to be separated is introduced into the pre-separator (1) through the first inlet (14). Under the action of centrifugal force, the small-particle-size oxamide slurry enters the small-particle-size oxamide slurry zone (22) through the first outlet (15), and the large-particle-size oxamide slurry enters the large-particle-size oxamide slurry zone (21) through the second outlet (16). 2) Control the drum filter (3) to first immerse itself in the large particle size oxalamide slurry zone (21) during the rotation process, forming a large particle size oxalamide slurry filter cake (31) on the outer surface of the drum filter (3); then rotate the drum filter (3) to immerse itself in the small particle size oxalamide slurry zone (22), forming a small particle size oxalamide slurry filter cake (32) on the outer surface of the large particle size oxalamide slurry filter cake (31); 3) The filtrate formed by the rotary drum filter (3) enters the filtrate tank (4) from the outlet, thus realizing the solid-liquid separation of the oxalamide slurry.

10. The solid-liquid separation method for oxalamide slurry according to claim 9, characterized in that, In step (1), the D50 of the large-particle-size oxalamide slurry is ≥45μm; the particle size D50 of the small-particle-size oxalamide slurry is <45μm. And / or, in step (2), the liquid level of the large-particle-size oxalamide slurry zone (21) and the liquid level of the small-particle-size oxalamide slurry zone (22) are equal; And / or, in step (2), the internal and external pressure difference of the drum filter (3) during the filtration process is 0.03~1.0 MPa.

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