Filtering device for production of p-nitrobenzoic acid

Abstract

The utility model relates to the technical field of p-nitrobenzoic acid production, in particular to a p-nitrobenzoic acid production filtering device which comprises a sealable suction filtration container, the interior of the suction filtration container is divided into a filtering cavity located on the upper portion and a liquid storage cavity located on the lower portion, and a filtering layer is arranged in the filtering cavity. The suction filtration container is further connected with a vacuum pump through an exhaust pipe, the vacuum pump is used for forming a negative pressure environment in the suction filtration container, the pulse type negative pressure adjusting assembly comprises a first electromagnetic valve, a controller and a timer, the first electromagnetic valve is arranged on the exhaust pipe, and the controller is electrically connected with the first electromagnetic valve. According to the utility model, the pulse type negative pressure adjusting component is used for exhausting air, and the air is fed when the air exhausting is stopped, so that periodic negative pressure and positive pressure alternately act on the filter cake, periodic strain is generated in the filter cake, a compact layer on the surface of the filter cake generates microcracks due to repeated stress, and the filtrate permeability is improved.

Description

Technical Field

[0001] This utility model relates to the field of p-nitrobenzoic acid production technology, and in particular to a filtration device for p-nitrobenzoic acid production. Background Technology

[0002] In the production process of p-nitrobenzoic acid, filtration is a crucial separation step, the purpose of which is to separate the p-nitrobenzoic acid solid produced by the reaction from the mixed solution. Currently, most companies use traditional vacuum filtration devices for filtration. These devices are usually equipped with a single layer of filter media and rely on constant negative pressure for vacuum filtration.

[0003] However, this traditional filtration method has a core problem: filter media clogging leads to a sharp drop in filtration efficiency. Due to the small size of p-nitrobenzoic acid crystals and the presence of impurities in the reaction solution, under the continuous action of constant negative pressure, solid particles will quickly accumulate tightly on the surface of the filter media to form a filter cake. As the filtration continues, the filter cake gradually thickens and is compacted, and the pores of the filter media are largely blocked, resulting in a continuous increase in the resistance of the liquid to passing through the filter media and a decrease in filtration efficiency. Utility Model Content

[0004] This invention provides a filtration device for the production of p-nitrobenzoic acid to solve the problems existing in the prior art.

[0005] The technical problem solved by this utility model is achieved by the following technical solution:

[0006] A filtration apparatus for the production of p-nitrobenzoic acid includes a sealable filtration container. The interior of the filtration container is divided into an upper filtration chamber and a lower liquid storage chamber. The filtration chamber is provided with a filter layer. The filtration container is also connected to a vacuum pump via an air extraction pipe to create a negative pressure environment inside the filtration container. The apparatus also includes a pulse-type negative pressure regulating component and an air inlet pipe. The pulse-type negative pressure regulating component includes a first solenoid valve disposed on the air extraction pipe, a controller electrically connected to the first solenoid valve, and a timer. The controller is used to periodically turn the vacuum pump on or off under the control of the timer. The air inlet pipe is provided with a second solenoid valve electrically connected to the controller. The controller is also configured to activate the second solenoid valve to open and allow air to enter the filtration container when the vacuum pump is turned off.

[0007] Preferably, the pumping flow rate of the vacuum pump is greater than the intake flow rate of the intake pipe per unit time.

[0008] Preferably, the output end of the air intake pipe is connected to multiple branch pipes via an annular pipe, and the outlet end of the branch pipe is configured not to face the filter layer.

[0009] Preferably, the inner wall of the filtration container is provided with a flange, and the filter layer is detachably installed on the flange through an annular connector.

[0010] Preferably, the filter layer includes an upper filter membrane and a lower support layer. The lower support layer is a porous grid support structure, and its grid pore size is larger than that of the upper filter membrane, which is used to support the upper filter membrane.

[0011] Preferably, the portion of the filtration container located in the filtration chamber has a transparent observation port.

[0012] The beneficial effects of this invention are as follows: by using a pulse-type negative pressure regulating component to draw air and then introducing air when the drawing stops, the filter cake is subjected to alternating negative and positive pressures periodically. During the negative pressure drawing phase, the filter cake is subjected to a downward pulling force; when the air is introduced, positive pressure acts on the filter cake, generating a reverse thrust. This alternating stress causes periodic strain inside the filter cake, resulting in micro-cracks appearing on the dense layer on the surface of the filter cake due to repeated stress, thereby improving the permeability of the filtrate. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0014] Figure 1 This is a schematic diagram of the isometric structure provided by this utility model;

[0015] Figure 2 A cross-sectional structural schematic diagram provided for this utility model;

[0016] Figure 3 This invention provides a schematic diagram of the cross-sectional structure of the filter layer.

[0017] Figure 4 This is a system block diagram provided in this utility model.

[0018] In the diagram, 1. Filter container; 11. Filter chamber; 12. Liquid storage chamber; 13. Observation port; 2. Filter layer; 21. Upper filter membrane; 22. Lower support layer; 3. Suction pipe; 4. Vacuum pump; 5. First solenoid valve; 51. Controller; 52. Timer; 6. Inlet pipe; 62. Second solenoid valve; 63. Annular pipe; 64. Diverter pipe; 7. Flange; 8. Annular connector. Detailed Implementation

[0019] To make the technical means, creative features, objectives and effects of this utility model easier to understand, the following description, in conjunction with specific illustrations, further elaborates on this utility model.

[0020] Reference Figures 1-4 As shown, a filtration device for the production of p-nitrobenzoic acid includes a sealable filtration container 1. The interior of the filtration container 1 is divided into an upper filtration chamber 11 and a lower liquid storage chamber 12. The filtration chamber 11 is equipped with a filter layer 2. A vacuum pump 4 for creating a negative pressure environment inside the filtration container 1 is connected to the filtration container 1 via a suction pipe 3. A cap is detachably connected to the upper end of the filtration container 1. When the cap is connected to the filtration container 1, the filtration container 1 is sealed. When the cap is opened, a nitrobenzoic acid solution can be poured into the filtration container 1, and then the vacuum pump 4 is used to evacuate air to achieve the production of p-nitrobenzoic acid inside the filtration container 1. Negative pressure causes the filtrate to fall into the storage chamber 12 after passing through the filter layer 2, while the filtered solids remain in the filter layer 2 inside the filter chamber 11. As the negative pressure increases, the solid particles are gradually compressed and compacted to form a filter cake. At this time, the resistance of the filtrate increases and the filtration efficiency decreases. Therefore, this solution also includes a pulse negative pressure regulating component and an air inlet pipe 6. The pulse negative pressure regulating component includes a first solenoid valve 5 installed on the air extraction pipe 3, a controller 51 electrically connected to the first solenoid valve 5, and a timer 52. The controller 51 is used to realize the periodic opening or closing of the vacuum pump 4 under the control of the timer 52.

[0021] Specifically, before filtration begins, timer 52 can be set with time parameters, such as 5 minutes. The first solenoid valve 5 is closed, blocking the air extraction pipe 3 and maintaining normal pressure inside the filter chamber 11. When the filtration program starts, timer 52 begins timing, and simultaneously, controller 51 receives the start signal and outputs a signal to the first solenoid valve 5, energizing and opening it. At this time, vacuum pump 4 starts, drawing air from the filtration container 1 through the air extraction pipe 3. The pressure inside the filter chamber 11 gradually decreases, creating a negative pressure environment. Under this negative pressure, the filtrate passes through the filter layer 2 inside the filter chamber 11, while solid particles are trapped within the filter layer 2. As the negative pressure increases, the solid particles are gradually compressed and compacted, forming a filter cake. When timer 52 expires, vacuum pump 4 is turned off to stop the filtration process. The filter cake is supplied with air, and a second solenoid valve 62 electrically connected to the controller 51 is also provided on the air inlet pipe 6. The controller 51 is also configured to activate the second solenoid valve 62 to open and supply air into the filtration container 1 when the vacuum pump 4 is turned off. At this time, the controller 51 controls the second solenoid valve 62 to open and inject a certain amount of air into the filtration container 1 through the air inlet pipe 6. During the negative pressure suction stage, the filter cake is subjected to a downward pulling force. When it switches to the air intake stage, the positive pressure acts on the surface of the filter cake and generates a reverse thrust. This alternating stress causes periodic strain inside the filter cake, causing microcracks to appear in the dense layer on the surface of the filter cake due to repeated stress. These microcracks are like newly added liquid flow channels, reducing the resistance of the filtrate through the filter cake. The liquid that was originally sealed inside the filter cake is more easily discharged in the micro channels generated by the stress change.

[0022] Furthermore, within a unit time, the air flow rate of the vacuum pump 4 is greater than the air flow rate of the inlet pipe 6, and the time for the controller 51 to control the second solenoid valve 62 to open is less than the pause time of the vacuum pump 4, so that the filter chamber 11 is continuously kept under negative pressure. Without interrupting the negative pressure, the permeability of the filter cake is continuously improved, avoiding the problem of direct compaction of the filter cake in traditional continuous filtration.

[0023] Among them, reference Figure 2 As shown, the output end of the air inlet pipe 6 is connected to multiple diversion pipes 64 through an annular pipe 63. The outlet end of the diversion pipe 64 is set not to face the filter layer 2, but can face downward or towards the inner wall of the filtration container 1. The reasonable layout of the outlet of the diversion pipe 64 allows the airflow to diffuse slowly in the cavity, avoiding pressure concentration caused by direct upward flow to the filter layer 2. After the airflow is evenly dispersed, the filter layer 2 is subjected to more balanced force, avoiding premature failure of local areas due to excessive interception of impurities, improving the stability of filtration efficiency, and also preventing the filtrate from entering the diversion pipe 64.

[0024] Reference Figure 2As shown, the inner wall of the filtration container 1 is provided with a flange 7, and the filter layer 2 can be directly installed on the flange 7 by means of an annular connector 8. After opening the cap, the filter layer 2 can be replaced by removing the annular connector 8 from the flange 7, which is more convenient.

[0025] Among them, reference Figure 3 As shown, the filter layer 2 includes an upper filter membrane 21 and a lower support layer 22. The lower support layer 22 is a porous mesh support structure with a mesh pore size larger than that of the upper filter membrane 21, used to support the upper filter membrane 21. The upper filter membrane 21 can be made of polyvinylidene fluoride microporous filter membrane, etc., used to trap fine particles in the feed liquid. The lower layer can be made of alumina ceramic honeycomb structure or other materials with a certain hardness. When the vacuum pump 4 is started, the liquid in the feed liquid flows downward through the micropores of the filter membrane, and solid particles are trapped to form a filter cake. The lower support layer 22 bears the weight of the filter membrane and the liquid pressure, preventing the filter membrane from deforming or breaking due to unidirectional negative pressure. Furthermore, since the mesh pore size of the lower support layer 22 is larger than that of the filter membrane, the filtrate can flow unimpeded through the mesh gaps to the bottom of the cavity after passing through the filter membrane, without increasing the flow resistance due to the presence of the support layer.

[0026] Reference Figure 1 As shown, furthermore, the part of the filtration container 1 located in the filtration chamber 11, i.e. the installation part of the filter layer 2, is provided with a transparent observation port 13, which makes it easy to directly observe the thickness and uniformity of the filter cake accumulation on the surface of the filter layer 2, making it more intuitive.

[0027] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claims. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. A p-nitrobenzoic acid production filtration device, characterized by, The container includes a sealable filtration container (1), the interior of which is divided into a filtration chamber (11) located at the top and a liquid storage chamber (12) located at the bottom. The filtration chamber (11) is provided with a filter layer (2). The filtration container (1) is also connected to a vacuum pump (4) through a suction pipe (3) to create a negative pressure environment inside the filtration container (1). It also includes a pulsed negative pressure regulating component, which includes a first solenoid valve (5) disposed on the suction pipe (3), a controller (51) electrically connected to the first solenoid valve (5), and a timer (52). The controller (51) is used to realize the periodic opening or closing of the vacuum pump (4) under the control of the timer (52). An air inlet pipe (6) is provided with a second solenoid valve (62) electrically connected to a controller (51). The controller (51) is also configured to activate the second solenoid valve (62) to open the air intake into the filtration container (1) when the vacuum pump (4) is turned off.

2. The p-nitrobenzoic acid production filtering device according to claim 1, characterized by, Within a unit of time, the pumping flow rate of the vacuum pump (4) is greater than the inlet flow rate of the inlet pipe (6).

3. The device for filtering p-nitrobenzoic acid production according to claim 1, characterized in that, The output end of the air inlet pipe (6) is connected to a plurality of branch pipes (64) through an annular pipe (63), and the outlet end of the branch pipe (64) is configured not to face the filter layer (2).

4. The device for filtering p-nitrobenzoic acid production according to claim 1, characterized in that, The inner wall of the filtration container (1) is provided with a flange (7), and the filter layer (2) is detachably installed on the flange (7) through an annular connector (8).

5. The p-nitrobenzoic acid production filtering device according to claim 1, characterized by, The filter layer (2) includes an upper filter membrane (21) and a lower support layer (22). The lower support layer (22) is a porous grid support structure, and its grid pore size is larger than that of the upper filter membrane (21), which is used to support the upper filter membrane (21).

6. The device for filtering p-nitrobenzoic acid production according to any one of claims 1-5, characterized in that, The portion of the filtration container (1) located in the filtration chamber (11) is provided with a transparent observation port (13).

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