Raw material mixing device for p-nitrobenzoic acid production

Abstract

The utility model belongs to the technical field of raw material mixing, and particularly relates to a raw material mixing device for p-nitrobenzoic acid production, which comprises a reaction kettle used for providing a reaction place for raw material mixing and reaction; the stirring assembly is mounted in the reaction kettle; the heating equipment is used for providing heat energy for raw material reaction; the power assembly is connected with the heating equipment; the cooling equipment is used for cooling the reaction kettle when the temperature in the reaction kettle exceeds a preset threshold value; the temperature sensor is used for monitoring the reaction temperature in the reaction kettle in real time; when the temperature exceeds a preset threshold value, controlling the power assembly to drive the heating equipment to be separated from the reaction kettle, and starting the cooling equipment; when the temperature recovers to a safe range, the power assembly is controlled to drive the heating equipment to reset, and the cooling equipment is stopped, the duration of temperature out-of-control is greatly shortened through the double guarantee mechanism of cutting off the heat source and actively cooling, the method is particularly suitable for key reaction steps which are prone to heat release in p-nitrobenzoic acid synthesis, and side reactions can be effectively restrained.

Description

Technical Field

[0001] This utility model belongs to the field of raw material mixing technology, specifically relating to a raw material mixing device for the production of p-nitrobenzoic acid. Background Technology

[0002] p-Nitrobenzoic acid is an important organic chemical intermediate widely used in pharmaceuticals (such as the synthesis of antibiotics and antipyretic analgesics), pesticides (such as the production of herbicides and fungicides), dyes (such as intermediates for azo dyes), and polymer materials (such as functional polymer monomers). Its production process typically uses p-nitrotoluene as a starting material, obtained through an oxidation reaction (such as nitric acid oxidation or air catalytic oxidation). Strict control of the raw material ratio, reaction temperature, and mixing uniformity is required during the reaction to ensure product yield, purity, and reaction safety.

[0003] In the traditional production of p-nitrobenzoic acid, the core equipment for raw material mixing and reaction is the reactor. The reactor must simultaneously meet the functional requirements of raw material mixing, heat transfer, and temperature control: on the one hand, the raw materials (such as p-nitrobenzoic acid precursors, oxidants, catalysts, etc.) need to be uniformly dispersed through mechanical stirring to avoid side reactions or byproducts caused by local concentration differences; on the other hand, the reaction is highly exothermic, and heating equipment is needed to maintain the temperature conditions required for the reaction, while avoiding excessively high temperatures that could lead to side reactions (such as raw material carbonization and product decomposition) or safety accidents (such as reactor overpressure and leakage).

[0004] However, existing production facilities face the following technical bottlenecks in actual operation:

[0005] 1. Significant Temperature Control Lag: Traditional reactors typically use a single temperature sensor (e.g., mounted on the reactor wall or jacket) to monitor temperature, combined with a PID controller to adjust the heating power. However, uneven heat distribution in the reaction system (e.g., localized overheating), sensor response delays (especially the temperature difference between the reactor wall and the actual internal temperature), and the thermal inertia of the heating equipment (e.g., slow heating / cooling rates of the electric heating jacket) result in a lag in temperature control. For example, during raw material mixing, when concentrated sulfuric acid is added dropwise, causing a sudden increase in the rate of exothermic reaction, traditional equipment struggles to reduce heating power in time, easily leading to localized temperature exceedances, which can affect product quality or trigger safety risks.

[0006] 2. Thermal coupling problem between heating equipment and reactor: Existing heating equipment (such as fixed electric heating jackets) is usually directly attached to the outer wall of the reactor. When the reaction temperature exceeds the preset threshold, cooling is only achieved by reducing the heating power (such as adjusting the voltage) or starting the cooling equipment. However, the continuous contact between the heating equipment and the outer wall of the reactor causes heat to be continuously transferred into the reactor (especially residual heat from the equipment), further exacerbating the risk of temperature runaway. It takes a long time (such as several minutes to tens of minutes) to restore the temperature to a safe range, affecting production efficiency. Utility Model Content

[0007] To address the above problems, the purpose of this utility model is to provide a raw material mixing device for the production of p-nitrobenzoic acid, thereby solving the problems mentioned in the background art.

[0008] This invention provides a raw material mixing device for the production of p-nitrobenzoic acid, comprising a reaction vessel for providing a reaction site for raw material mixing and reaction; a stirring assembly installed inside the reaction vessel for mechanically mixing and stirring the raw materials; a heating device disposed on the reaction vessel for providing heat energy for the raw material reaction; a power assembly connected to the heating device for supporting the heating device and driving the heating device to detach from the reaction vessel when the temperature inside the reaction vessel exceeds a preset threshold; a cooling device for cooling the reaction vessel when the temperature inside the reaction vessel exceeds the preset threshold; a temperature sensor installed above the stirring assembly for real-time monitoring of the reaction temperature inside the reaction vessel; and a controller electrically connected to the temperature sensor for controlling the operating status of the stirring assembly, heating device, power assembly, and cooling device based on the temperature signal monitored by the temperature sensor; when the temperature exceeds the preset threshold, controlling the power assembly to drive the heating device to detach from the reaction vessel and start the cooling device; when the temperature returns to a safe range, controlling the power assembly to drive the heating device to reset and stop the cooling device.

[0009] Preferably, when the temperature sensor detects that the temperature inside the reactor exceeds a preset threshold, the controller reduces the heating temperature of the heating device and increases the stirring speed of the stirring assembly; when the temperature sensor detects that the temperature inside the reactor returns to a safe range, the controller controls the stirring assembly to resume its original stirring speed.

[0010] Preferably, the power assembly includes an electric push rod, one end of which is connected to the heating device and the other end of which is fixed to the reactor support; a slide rail, disposed on the support, for guiding the heating device to move vertically; a position sensor, installed at the bottom of the heating device, for measuring the relative position of the heating device and the reactor in real time and transmitting the position signal to the controller; and an electromagnetic locking device, for locking the relative position of the heating device and the reactor under normal operating conditions to prevent accidental detachment.

[0011] Preferably, the cooling device includes a cooling jacket installed on the outside of the reactor for cooling by circulating cooling water; a cooling water tank, the outlet of which is connected to the cooling jacket via a first pipe, and the return port of which is connected to the cooling jacket via a second pipe; and a circulation pump installed on the first pipe for circulating the cooling water.

[0012] Preferably, the stirring assembly includes a stirring paddle suspended inside the reactor by a top plate at the top of the reactor, comprising multiple parallel flat plates for enhancing axial mixing; a vertical plate for connecting adjacent flat plates to enhance radial mixing; a curved plate disposed at the bottom of the reactor to prevent bottom sedimentation; a motor mounted on the top of the stirring paddle for driving the stirring paddle to rotate; and a speed sensor mounted on the motor or stirring paddle for real-time monitoring of the stirring speed and transmitting the signal to the controller.

[0013] Preferably, the cooling device further includes a phase change material layer, which is filled between the cooling jacket and the reactor to extend the cooling time and buffer temperature fluctuations.

[0014] The beneficial effects of this utility model are: by setting up a power component, when the temperature sensor detects that the reaction temperature exceeds the preset threshold, the heating device is automatically driven to detach from the reaction vessel, quickly cutting off the heat source, preventing the temperature from rising further from the source, and avoiding the generation of by-products, material waste or safety accidents caused by overheating.

[0015] As the heating equipment disengages, the controller simultaneously activates the cooling system, rapidly restoring the reactor temperature from the abnormally high level to a safe range through forced cooling. This dual protection mechanism of "cutting off the heat source + active cooling" significantly shortens the duration of temperature runaway, and is particularly suitable for the exothermic key reaction steps in the synthesis of p-nitrobenzoic acid. It can effectively suppress side reactions and improve the selectivity and yield of the target product.

[0016] A temperature sensor monitors the reaction temperature above the stirring assembly in real time and transmits the signal to the controller. The controller dynamically adjusts the operating status of the heating and cooling equipment based on preset thresholds: specifically, it issues an early warning when the temperature approaches the threshold, immediately performs disconnection and cooling operations when the temperature exceeds the threshold, and automatically resets the heating equipment and shuts down the cooling system when the temperature drops back to a safe range. This closed-loop control logic reduces the need for manual intervention, avoids the lag caused by relying on operator experience, and significantly improves the automation level and process reproducibility of the reaction process. Attached Figure Description

[0017] Figure 1 This is a three-dimensional structural diagram of the present invention;

[0018] Figure 2 This is a top view of the structure of this utility model;

[0019] Figure 3 This is a side sectional view of the present invention.

[0020] Figure 4 This is a side sectional view of the structure of this utility model.

[0021] Figure 5 This is a schematic diagram of the heating device in the state of being detached from the reaction vessel in this utility model.

[0022] In the diagram: 1. Reactor; 2. Stirring assembly; 3. Heating equipment; 4. Power assembly; 5. Cooling equipment; 6. Temperature sensor; 7. Controller; 8. Electric actuator; 9. Support; 10. Position sensor; 11. Cooling jacket; 12. Cooling water tank; 13. Circulating pump; 14. Pipe 1; 15. Pipe 2; 16. Stirring paddle; 17. Flat plate; 18. Vertical plate; 19. Bend plate; 20. Motor. Detailed Implementation

[0023] To enable those skilled in the art to better understand the technical solution of this utility model, the present utility model will be described in detail below with reference to the accompanying drawings. The description in this part is only exemplary and explanatory, and should not be used to limit the scope of protection of this utility model in any way.

[0024] In traditional reactors, the heating equipment 3 (such as electric heating tubes or heat transfer oil jackets) is usually fixedly installed outside the reactor body. When the reaction temperature rises abnormally (such as exothermic side reactions or temperature control failure), the continuous heating of the heating equipment 3 may lead to local overheating, or even cause material decomposition, carbonization, or equipment damage. Based on the above problems, the present invention adopts the following improvement method to solve them.

[0025] like Figure 1-5 As shown, a raw material mixing device for the production of p-nitrobenzoic acid includes a reactor 1 for providing a reaction site for raw material mixing and reaction. Inside the reactor 1, a stirring assembly 2 for mechanically mixing and stirring the raw materials is installed. The stirring assembly 2 includes a stirring paddle 16 and a motor 20. The stirring paddle 16 is suspended inside the reactor 1 by a top plate. The motor 20 is mounted on the top of the stirring paddle 16 to drive its rotation. To facilitate monitoring of the stirring speed, a speed sensor is also installed on the motor 20 or the stirring paddle 16. This speed sensor is electrically connected to a controller 7 to provide a signal indicating the rotational speed of the stirring paddle 16. The device also includes a heating device 3 mounted on the reactor 1 via a power assembly 4. This heating device 3 provides heat energy for the raw material reaction. The heating device 3 employs an oil bath, a common type of heating device in the prior art. Figure 4As shown, the power assembly 4 includes an electric push rod 8, one end of which is connected to the heating device 3 (oil bath) and the other end is fixed to the support 9 of the reactor 1; a slide rail mounted on the support 9 for guiding the heating device 3 to move vertically; and a position sensor 10 mounted on the bottom of the heating device 3 for real-time measurement of the relative position of the heating device 3 and the reactor 1 and transmitting the position signal to the controller 7; it also includes a temperature sensor 6, which is mounted above the stirring paddle 16 for real-time monitoring of the reaction temperature inside the reactor 1; when the temperature sensor 6 detects a temperature inside the reactor 1... When the temperature exceeds a preset temperature threshold, the temperature signal is transmitted to the controller 7. The controller 7 controls the operation of the cooling device 5 based on the temperature signal monitored by the temperature sensor 6. The cooling device 5 mainly includes a cooling jacket 11 installed outside the reactor 1, which is cooled by circulating cooling water; a cooling water tank 12 whose outlet is connected to the cooling jacket 11 via pipe 14 and whose return outlet is connected to the cooling jacket 11 via pipe 2 15; and a cooling water circulation pump 13 installed on pipe 14 for circulating the cooling water. When the cooling water enters the cooling jacket 11 along pipe 14, such as... Figure 5The cooling jacket 11 shown is spiral-shaped and evenly wound around the outer wall of the reactor 1, enabling uniform heating of the reactor 1. Alternatively, it can be shaped like a box conforming to the outer contour of the reactor 1, fitting around its exterior to remove heat from the outside. The heat then flows to pipe 15, where it is cooled by water or air (air-cooled condensers exchange heat between cooling water and air, requiring no water resources, but with lower heat transfer efficiency, a heat transfer coefficient of approximately 50-100 W / (m²·K), and requiring a larger heat exchange area; these heat dissipation methods are existing technologies well-known to those skilled in the art, not shown in detail in the figure, and will not be elaborated upon here). The heat is then carried away from the cooling water and flows back to the cooling water tank 12. The cooling jacket 11 rapidly removes heat through circulating cooling water, achieving a cooling rate of 5-10℃ / min, significantly better than natural cooling (approximately 1-2℃ / min). In the production of p-nitrobenzoic acid, in the event of a sudden overheating, the temperature can be reduced from 190℃ to 170℃ within 2 minutes, preventing the reaction from spiraling out of control.The cooling jacket 11 is in direct contact with the reactor 1, resulting in high heat exchange efficiency. The circulating pump 13 drives the cooling water circulation, eliminating the need for complex piping and reducing maintenance costs. To extend the cooling time and buffer temperature fluctuations, a phase change material layer is installed between the cooling jacket 11 and the reactor 1. The phase change material (such as paraffin wax) undergoes a phase change (solid to liquid) during heat absorption, absorbing a large amount of latent heat and extending the cooling time (to 2-3 times that of the cooling jacket 11 acting alone), reducing the frequency of cooling water circulation and lowering the energy consumption of the circulating pump 13. Simultaneously, the controller 7 also controls the stirring assembly 2 (operating parameters of the motor 20) and the heating equipment. 3. The operating status of the oil bath medium in the oil bath and the power component 4 (contraction or extension of the electric push rod 8). Specifically, solid p-nitrotoluene and solid sodium dichromate need to be dissolved and reacted in a concentrated sulfuric acid-water system. During the raw material mixing process, when concentrated sulfuric acid is added, the temperature inside the reactor 1 will rise. When the temperature exceeds a preset threshold, the power component 4 is controlled to drive the heating device 3 to detach from the reactor 1. First, according to the relative position of the heating device 3 to the reactor 1 monitored by the position sensor 10, the electric push rod 8 is controlled to retract, driving the heating device 3 to move downwards a corresponding distance, so that the heating device 3 detaches from the reactor. Reactor 1 is cooled, and the heating temperature of heating device 3 is reduced to 10-20 degrees Celsius below a preset threshold to save energy. Simultaneously, cooling device 5 is activated to cool reactor 1, and the stirring speed of stirring component 2 is increased. Based on the stirring speed monitored by the speed sensor, the operating power of motor 20 is increased accordingly. When the temperature returns to a safe range, power component 4 is controlled to reset heating device 3, and cooling device 5 is stopped from cooling reactor 1. Simultaneously, stirring component 2 is controlled to resume its original stirring speed. For example, in the production of p-nitrobenzoic acid, if the temperature exceeds... After the heating device 3 is disconnected from the 185℃ (preset threshold), the cooling device 5 can reduce the temperature to a safe range (e.g., 160-170℃) within 30 seconds, reducing raw material loss (reducing it by 5%-10%). Adjust the oil bath heating temperature to 10-20℃ lower than the original target value (e.g., from 180℃ to 160℃), and continue running for 5-10 minutes. Observe the temperature change of the reaction vessel 1, and increase it by 5-10℃ every 5 minutes until it returns to the target temperature (e.g., 180℃). Maintain the temperature at the target temperature for 10-15 minutes to confirm that there is no overheating trend, avoid thermal shock, monitor temperature changes, and adjust the heating power in a timely manner.

[0026] Furthermore, such as Figure 1-2As shown, in order to accelerate the mixing speed of raw materials, the stirring paddle 16 is improved, including multiple parallel flat plates 17 for enhancing axial mixing; vertical plates 18 for connecting two adjacent flat plates 17 and enhancing radial mixing; and a curved plate 19 disposed at the bottom of the reactor 1 to prevent bottom deposition, wherein the curved plate 19 is adapted to the inner wall of the reactor 1. The conventional stirring paddle 16 mixes raw materials uniformly, and the yield of p-nitrobenzoic acid is 85%. The stirring paddle 16 mixes raw materials uniformly, and the yield of p-nitrobenzoic acid can reach 92%.

[0027] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Specific examples have been used in this document to illustrate the principles and implementation methods of this utility model. The above examples are merely to aid in understanding the method and core ideas of this utility model. The above descriptions are only preferred embodiments of this utility model. It should be pointed out that, due to the limitations of written expression, there are objectively infinite specific structures. For those skilled in the art, several improvements, modifications, or variations can be made without departing from the principles of this utility model, and the above technical features can be combined in an appropriate manner. These improvements, modifications, variations, or combinations, or the direct application of the inventive concept and technical solution to other situations without modification, should all be considered within the scope of protection of this utility model.

Claims

1. A raw material mixing device for the production of p-nitrobenzoic acid, characterized in that, include: The reactor (1) is used to provide a reaction site for mixing and reacting raw materials; A stirring assembly (2) is installed inside the reactor (1) for mechanically mixing and stirring the raw materials; Heating equipment (3) is installed on the reactor (1) to provide heat energy for the reaction of raw materials; The power unit (4) is connected to the heating device (3) to support the heating device (3) and to drive the heating device (3) to detach from the reactor (1) when the temperature inside the reactor (1) exceeds a preset threshold. Cooling device (5) is used to cool down the reactor (1) when the temperature inside the reactor (1) exceeds a preset threshold. A temperature sensor (6) is installed above the stirring assembly (2) to monitor the reaction temperature inside the reactor (1) in real time; The controller (7) is electrically connected to the temperature sensor (6) and is used to control the operating status of the stirring assembly (2), the heating device (3), the power assembly (4) and the cooling device (5) according to the temperature signal monitored by the temperature sensor (6); When the temperature exceeds the preset threshold, the power component (4) is controlled to drive the heating device (3) to detach from the reactor (1) and the cooling device (5) is started. When the temperature returns to a safe range, the power unit (4) is controlled to drive the heating device (3) to reset and the cooling device (5) is stopped.

2. The raw material mixing device for the production of p-nitrobenzoic acid according to claim 1, characterized in that: When the temperature sensor (6) detects that the temperature inside the reactor (1) exceeds the preset threshold, the controller (7) reduces the heating temperature of the heating device (3) and increases the stirring speed of the stirring assembly (2); when the temperature sensor (6) detects that the temperature inside the reactor (1) returns to a safe range, the controller (7) controls the stirring assembly (2) to return to its original stirring speed.

3. The raw material mixing device for the production of p-nitrobenzoic acid according to claim 1, characterized in that: The power assembly (4) includes: An electric push rod (8) is connected at one end to the heating device (3) and at the other end to the support (9) of the reactor (1). A slide rail, mounted on the bracket (9), is used to guide the heating device (3) to move in the vertical direction; A position sensor (10) is installed at the bottom of the heating device (3) to measure the relative position of the heating device (3) and the reactor (1) in real time and transmit the position signal to the controller (7). An electromagnetic locking device is used to lock the relative positions of the heating equipment (3) and the reactor (1) under normal operating conditions to prevent accidental separation.

4. The raw material mixing device for the production of p-nitrobenzoic acid according to claim 1, characterized in that: The cooling device (5) includes: A cooling jacket (11) is installed on the outside of the reactor (1) and is cooled by circulating cooling water; The outlet of the cooling water tank (12) is connected to the cooling jacket (11) via pipe one (14), and the return outlet is connected to the cooling jacket (11) via pipe two (15). A circulation pump (13) is installed on the first pipe (14) to circulate cooling water.

5. The raw material mixing device for the production of p-nitrobenzoic acid according to claim 1, characterized in that: The stirring assembly (2) includes: A stirring paddle (16), suspended inside the reactor (1) by a top plate at the top of the reactor (1), comprises: Multiple parallel plates (17) are used to enhance axial mixing; Vertical plate (18) is used to connect two adjacent plates (17) to enhance radial mixing; An inclined plate (19) is placed at the bottom of the reactor (1) to prevent bottom sedimentation; A motor (20) is installed at the top of the stirring paddle (16) to drive the stirring paddle (16) to rotate; A speed sensor, installed on the motor (20) or the agitator (16), is used to monitor the stirring speed in real time and transmit the signal to the controller (7).

6. The raw material mixing device for the production of p-nitrobenzoic acid according to claim 4, characterized in that: The cooling device (5) also includes a phase change material layer, which is filled between the cooling jacket (11) and the reactor (1) to extend the cooling time and buffer temperature fluctuations.

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