High-selectivity continuous production device for nitration of o-dichlorobenzene

Abstract

The application relates to a high-selectivity o-dichlorobenzene nitration continuous production device and belongs to the technical field of chemical reaction equipment. The device comprises a multistage tubular reactor, a buffer tank, an underground ice water quenching pool, a power-off discharge assembly, a leakage monitoring assembly and a flow self-adjusting assembly. The flow self-adjusting assembly drives the deformation of a corrugated diaphragm by using the air pressure in the buffer tank, drives the linear adjustment of a throttle seat to adjust the feeding flow, realizes self-adaptive stable pressure feeding without electric control, the leakage monitoring assembly expands after absorbing the flange leakage liquid, drives the movement of a sliding rod and visually shows the alarm, realizes mechanical monitoring of hidden micro-leakage, and the power-off discharge assembly breaks the ceramic sealing plate by the gravity falling of a counterweight block when power is off, rapidly discharges the retained material to the underground ice water quenching pool for cooling. The application realizes self-adaptive adjustment of the feeding flow, accurate monitoring of flange micro-leakage and emergency discharge when power is off through a pure mechanical structure, and significantly improves the safety, stability and product selectivity of the nitration process.

Description

Technical Field

[0001] This invention belongs to the technical field of chemical reaction equipment and relates to a highly selective continuous production device for o-dichlorobenzene nitration. Background Technology

[0002] The nitration of o-dichlorobenzene is an important intermediate synthesis process in the fine chemical industry. It mainly involves the low-temperature liquid-phase nitration reaction of o-dichlorobenzene with a mixture of nitrate and sulfuric acid to prepare the target product. This reaction is a strongly exothermic and rapid reaction system, and the reaction process is prone to side reactions. Moreover, the nitration medium has extremely strong acid and alkali corrosiveness and highly dangerous flammable and explosive properties. At present, industrial production generally uses multi-stage tubular continuous reaction equipment to complete this process. Compared with batch reaction equipment, continuous tubular reaction can improve production efficiency to a certain extent, but there are still many substantial defects in actual industrial applications.

[0003] Currently, the feed flow control of traditional continuous nitration production equipment mostly relies on the linkage of electric regulating valves, pressure sensors, and DCS electronic control systems. The entire control system is highly dependent on power supply and precision electronic instruments. Nitration production workshops are in a high-concentration acid mist corrosive environment for a long time, and various sensors, instruments, and electronic control components are prone to corrosion, aging, signal drift, and response lag. Once a power outage occurs in the plant or instruments malfunction, the electronic flow control system will directly fail and will not be able to adaptively adjust the feed rate according to real-time pressure changes inside the reactor. When the pressure in the reaction system rises suddenly due to the accumulation of tail gas, the continuous feeding of excessive raw materials will exacerbate the reaction intensity, causing system overpressure and a significant increase in by-products. In severe cases, it may lead to safety hazards such as material surge and reaction runaway. At the same time, traditional electronic throttling structures are mostly fixed on-off regulation, and the throttling process is highly abrupt, which can easily cause material turbulence and pressure fluctuations inside the pipeline, further disrupting the stable reaction environment of low-temperature nitration and reducing the selectivity of the target product.

[0004] Secondly, the pipe connections between the tubular reactor and the buffer tank both use flange sealing structures, which are the weakest points where leakage is most likely to occur. Traditional production methods rely solely on manual periodic inspections to visually check for leaks. The micro-leakage and gap leakage that initially appear on the flanges are extremely difficult to detect in time. Long-term leakage of trace amounts of acidic media will continuously corrode the pipes, steel frames, and surrounding equipment, gradually expanding the potential for seal failure and eventually causing large-scale leakage accidents. The conventional practice is to periodically use pH test paper for manual detection or install expensive electronic acid mist probes (which are extremely susceptible to corrosion and damage). Micro-leakage is extremely difficult to detect in its early stages, and once it deteriorates, it often leads to large-scale acid splashing accidents.

[0005] In addition, when a sudden power outage occurs in the plant area, the equipment's electrical control system and automatic valves all fail. The nitrated materials remaining inside the reactor and buffer tank cannot be discharged in time, the exothermic reaction cannot be terminated quickly, and the continuous heat accumulation of the materials can easily cause major safety accidents such as overheating, overpressure, and boiling over. Relying solely on manual operation cannot achieve instantaneous emergency response. The overall safety redundancy of the equipment is low and cannot meet the safety production requirements of high-risk nitration processes.

[0006] Therefore, we propose a highly selective o-dichlorobenzene nitration continuous production unit to solve the problems mentioned above. Summary of the Invention

[0007] This invention addresses the problems of corrosion and malfunction of the electrical control system, difficulty in detecting micro-leakage in flanges, and loss of control during power outages in the continuous production of o-dichlorobenzene nitration. During the research and development process, it was found that existing technologies using electrically controlled regulating valves to adjust the feed flow are prone to corrosion and aging under strong acid conditions, signal drift, and complete failure upon power failure, easily leading to overpressure and uncontrolled reaction. Electronic acid mist sensors have short lifespans and are prone to false alarms in acid mist environments, failing to provide early warning of micro-leakage. Electrically controlled emergency relief valves fail to operate when power is lost, and the continuous release of heat from trapped materials can easily cause serious safety accidents such as overheating and explosions.

[0008] This invention designs a flow self-regulating component driven by the gas pressure of the buffer tank, which uses the pressure of the reaction system itself to achieve adaptive and stable feed flow. It also develops a visual monitoring component for flange micro-leakage triggered by acid expansion, which can capture initial hidden leaks that cannot be identified manually. Furthermore, it adopts a power failure gravity impact emergency discharge component, which automatically discharges high-risk materials into an underground ice water quenching pool when power is lost, providing a highly selective continuous production device for o-dichlorobenzene nitration.

[0009] To achieve the above objectives, the present invention provides the following technical solution: a highly selective o-dichlorobenzene nitration continuous production apparatus, comprising: a multi-stage tubular reactor, wherein a buffer tank is connected to the tail end of the multi-stage tubular reactor, an underground ice-water quenching pool is provided at the bottom of the buffer tank, the underground ice-water quenching pool is pre-buried underground, a tee pipe is connected to the bottom end of the buffer tank, one end of the tee pipe is connected to an extension pipe through a valve, and a power failure discharge component is provided at the bottom end of the tee pipe, which quickly discharges the material in the buffer tank into the underground ice-water quenching pool for cooling when the power is cut off; Multiple leakage monitoring components are respectively installed at the flange connection of the multi-stage tubular reactor and the buffer tank. Each leakage monitoring component includes a detection tube, multiple expansion blocks, and a sliding rod that works with the expansion blocks. The expansion blocks absorb the leaked liquid, and after absorption, the expansion drives the sliding rod to move upward, thereby monitoring the leakage. A flow self-regulating component is installed at the feed end of a multi-stage tubular reactor. The flow self-regulating component includes an installation cylinder vertically connected to the feed pipe, a corrugated diaphragm installed inside the installation cylinder, and a throttling seat connected to the bottom of the corrugated diaphragm. The installation cylinder is connected to a buffer tank. The air pressure inside the buffer tank, in conjunction with the corrugated diaphragm, drives the throttling seat to move up and down to control the flow rate.

[0010] Furthermore, the power failure relief assembly includes multiple support rods fixed to the inner wall of the buffer tank. An electromagnet block coaxial with the three-way pipe is fixed to the inner end of each support rod. A guide rod is fixed to the bottom of the electromagnet block, and the bottom end of the guide rod extends into the three-way pipe. A counterweight is slidably sleeved on the outer wall of the guide rod. The counterweight is attracted to the bottom of the electromagnet block. A nut ring is threaded onto the bottom end of the three-way pipe, and a ceramic sealing plate for sealing the bottom end of the three-way pipe is fixed inside the nut ring. When the electromagnet block is de-energized, the counterweight falls rapidly under the action of gravity and breaks the ceramic sealing plate.

[0011] Furthermore, the outer wall of the counterweight is provided with multiple rectangular openings II, and the bottom of the counterweight is formed with multiple impact sections.

[0012] Furthermore, a limiting ring II is fixedly provided at the bottom of the guide rod to limit the position of the counterweight block, so as to prevent the counterweight block from detaching from the guide rod.

[0013] Furthermore, the leakage monitoring component also includes two semi-circular covers, which are respectively fitted onto the pipes at both ends of the connecting flange. Each pipe at both ends of the connecting flange is fixedly fitted with a limiting ring I for limiting the position of the semi-circular cover. The detection tube is fixed to the bottom of one of the semi-circular covers, and one end of the other semi-circular cover has a groove adapted to the detection tube. The two semi-circular covers are fixedly connected by multiple bolts.

[0014] Furthermore, a fixing ring is fixed inside the detection tube, the sliding rod slides through the top of the fixing ring, a fixing plate is slidably installed inside the detection tube, the fixing plate is fixed to the bottom of the sliding rod, a plug is threaded to the bottom of the detection tube, a spring I is sleeved on the outer wall of the sliding rod, the two ends of the spring I abut against the bottom of the fixing ring and the top of the fixing plate respectively, and multiple expansion blocks are located at the bottom of the fixing plate. The spring I drives the fixing plate to move downward to compress the expansion blocks.

[0015] Furthermore, a pad is provided between two adjacent expansion blocks, and a rectangular opening I is provided on the outer wall of the fixing ring, the fixing plate and the pad. Liquid permeates downward through the rectangular opening I in sequence, and the multiple expansion blocks expand in sequence.

[0016] Furthermore, the detection tube is provided with a light-shielding film, and the section of the detection tube not covered by the light-shielding film forms a transparent part. Under normal conditions, the sliding rod is flush with the bottom of the transparent part. When leakage occurs, the sliding rod extends upward into the transparent part, and a conspicuous coating is applied to the top of the sliding rod.

[0017] Furthermore, a support plate is fixedly installed inside the mounting cylinder below the corrugated diaphragm. A connecting rod is fixedly installed at the bottom center of the corrugated diaphragm. The connecting rod slides through the top of the support plate. The throttling seat is fixed to the bottom of the connecting rod. A spring II is sleeved on the outer wall of the connecting rod. The two ends of the spring II abut against the bottom of the connecting rod and the top of the support plate, respectively. The spring II drives the corrugated diaphragm to overcome the gravity of the throttling seat and the connecting rod and keep it in a horizontal position. A cavity is formed between the top of the corrugated diaphragm and the mounting cylinder. The cavity is connected to the buffer tank through a pneumatic tube.

[0018] Furthermore, the top of the support plate is provided with air holes. When the middle part of the corrugated diaphragm hangs down, the air pressure below the corrugated diaphragm and the connecting rod drive the throttle seat to move downward.

[0019] The beneficial effects of this invention are as follows: 1. The highly selective o-dichlorobenzene nitration continuous production device disclosed in this invention uses a fatigue-resistant and corrosion-resistant corrugated diaphragm to sense pressure changes in the system, and a streamlined wedge-shaped throttling structure to achieve linear throttling control. When the pressure fluctuates, the flow rate can be finely adjusted instantly, avoiding the problems of electrical control delay and signal failure. It can still work normally under power failure conditions. The wedge-shaped throttling structure can smoothly change the cross-sectional area of ​​the pipeline flow, avoiding pipeline turbulence and pressure oscillation caused by sudden throttling, continuously stabilizing the low-temperature reaction environment inside the reactor, effectively suppressing the generation of side reactions, and greatly improving the product selectivity and production stability of the o-dichlorobenzene nitration reaction. 2. The highly selective o-dichlorobenzene nitration continuous production device disclosed in this invention achieves precise interception of micro-leaking media through an enclosed enclosure structure. It utilizes acidic media to trigger the expansion and deformation of the polymer structure, and coordinates with mechanical linkage to achieve visual leak early warning. The entire monitoring structure requires no power supply, has no electronic components, is resistant to acid mist corrosion, and can be on duty 24 / 7 under high-risk conditions for a long time. It can detect initial hidden micro-leaks that cannot be identified by human visual inspection, and can provide early warning at the initial stage of leakage potential. This facilitates timely maintenance and replacement of the sealing structure by staff, avoids long-term corrosion of equipment by trace amounts of acid, and avoids safety hazards such as equipment damage and material leakage caused by flange leakage from the source, significantly reducing equipment failure rate and downtime maintenance frequency. 3. The highly selective o-dichlorobenzene nitration continuous production device disclosed in this invention, through the setting of the power failure relief component, enables the automatic breaking of the sealing structure at the bottom of the pipeline in the instant of power failure, quickly opening the emergency relief channel, and allowing the high-risk nitration material retained in the reactor and buffer tank to be quickly discharged into the underground ice water quenching pool. Through the rapid quenching and cooling of the low-temperature water body, the exothermic reaction is terminated, which completely solves the safety problems of reaction runaway, material heat accumulation and temperature rise, and overpressure material rush after power failure of traditional equipment, and greatly improves the safety redundancy and extreme working condition protection capability of the device.

[0020] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0021] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein: Figure 1 This is a three-dimensional structural schematic diagram of a high-selectivity o-dichlorobenzene nitration continuous production apparatus according to the present invention; Figure 2 This is a schematic diagram of the bottom structure of the buffer tank in a high-selectivity o-dichlorobenzene nitration continuous production apparatus according to the present invention; Figure 3 This is a schematic diagram of the power failure discharge assembly installation structure of a high-selectivity o-dichlorobenzene nitration continuous production device according to the present invention; Figure 4 This is a schematic diagram of the counterweight structure of a high-selectivity o-dichlorobenzene nitration continuous production device according to the present invention; Figure 5 This is a cross-sectional structural diagram of a leakage monitoring component for a high-selectivity o-dichlorobenzene nitration continuous production apparatus according to the present invention; Figure 6 This is a schematic diagram of the semi-circular structure of a high-selectivity o-dichlorobenzene nitration continuous production apparatus according to the present invention; Figure 7 This is a perspective view of the detection tube structure of a high-selectivity o-dichlorobenzene nitration continuous production apparatus according to the present invention; Figure 8 This is a schematic diagram of the flow self-regulating component structure of a high-selectivity o-dichlorobenzene nitration continuous production device according to the present invention.

[0022] Reference numerals: 1. Multistage tubular reactor; 2. Buffer tank; 21. Tee; 22. Valve; 23. Extension pipe; 3. Underground ice water quenching tank; 4. Leakage monitoring assembly; 41. Semi-circular cover; 42. Limiting ring I; 43. Bolt; 44. Detection tube; 45. Fixing ring; 46. Sliding rod; 47. Fixing plate; 48. Expansion block; 49. Pad; 410. Spring I; 411. Plug; 412. Groove; 413. Transparent part; 414. Light shield 415. Rectangular orifice I; 5. Flow self-regulating assembly; 51. Mounting cylinder; 52. Corrugated diaphragm; 53. Connecting rod; 54. Spring II; 55. Throttling seat; 56. Cavity; 57. Air hole; 58. Support plate; 6. Air pressure capillary tube; 7. Power failure discharge assembly; 71. Support rod; 72. Electromagnet block; 73. Guide rod; 74. Counterweight block; 75. Limiting ring II; 76. Nut ring; 77. Ceramic sealing plate; 78. Rectangular orifice II; 79. Impact part. Detailed Implementation

[0023] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0024] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0025] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present 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, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0026] Example 1 like Figures 1-7 As shown, a high-selectivity o-dichlorobenzene nitration continuous production unit is mainly used for continuous low-temperature nitration reaction production of o-dichlorobenzene and nitrate-sulfur mixed acid. The entire unit includes a multi-stage tubular reactor 1, a buffer tank 2, an underground ice-water quenching pool 3, multiple sets of leakage monitoring components 4, a flow self-regulating component 5, and a power failure discharge component 7. All structural components in contact with acidic corrosive materials are made of acid-resistant and corrosion-resistant materials, which are suitable for the high-risk corrosive production conditions of nitration.

[0027] The multi-stage tubular reactor 1 is the core reaction unit of the entire system. It adopts a multi-section tubular flange splicing assembly structure, and a refrigerant heat exchange structure is set on the outside of the tubes to continuously remove the exothermic reaction generated by nitration, maintain a low-temperature reaction environment inside the tubes, ensure the selectivity of nitration, and reduce the generation of by-products. The tail end pipeline of the multi-stage tubular reactor 1 is connected to the buffer tank 2. The buffer tank 2 serves as a reaction pressure stabilization and material buffer structure, used to collect the materials completed in the multi-stage tubular reactor 1, and at the same time collect the gaseous tail gas generated by the entire reaction system, stabilizing the system pressure inside the entire pipeline and avoiding frequent pipeline pressure fluctuations that would affect the reaction effect.

[0028] The underground ice-water quenching pool 3 is pre-buried below the ground, directly below the buffer tank 2. It stores low-temperature cooling water and is specifically designed to receive, cool, and quench high-temperature, high-risk nitrification materials under extreme conditions, quickly terminating the violent exothermic reaction and mitigating safety risks. A three-way pipe 21 is fixedly connected to the bottom of the buffer tank 2, forming a three-way conduction structure to switch between material diversion and emergency release channels. One end of the three-way pipe 21 is connected to an extension pipe 23 via a valve 22. The valve 22 controls the opening and closing of the downstream material conveying channel. Under normal production conditions, the valve 22 remains open, allowing the reactants inside the buffer tank 2 to be stably conveyed to the subsequent refining process via the three-way pipe 21 and the extension pipe 23. The bottom end of the three-way pipe 21 is equipped with a power failure relief component 7. As an emergency safety protection structure for the entire device, the power failure relief component 7 can automatically open the emergency relief channel in the event of a sudden power outage in the plant area or a complete failure of the electrical control system. This allows the materials stored in the buffer tank 2 and the multi-stage tubular reactor 1 to be quickly discharged into the underground ice water quenching pool 3 to complete the cooling quenching and risk disposal.

[0029] Leakage monitoring components 4 are installed at the flange joints of each section of the multi-stage tubular reactor 1 and at the flange joints of various pipelines in the buffer tank 2. Multiple sets of leakage monitoring components 4 cover all easily leaking sealing points of the device, realizing all-weather automatic monitoring and early warning of concealed micro-leakage of flanges. The leakage monitoring components 4 adopt an enclosed sealing monitoring structure. Relying on the symmetrical protective cover, fastening structure, liquid flow guiding detection structure and elastic triggering structure working together, it can collect, identify and visualize the acidic media with minute leaks without affecting the stability of the flange seal. It is suitable for the complex operating conditions of long-term vibration and acid mist corrosion of the equipment.

[0030] Two semicircular covers 41 form a symmetrical interlocking protective structure, partially enclosing the outside of the pipe flange's mating joint, creating a sealed liquid collection cavity. Any trace amounts of acidic leakage seeping through the flange gap are completely trapped and collected inside the cavity, preventing leaks from flowing down the pipe wall and causing hidden hazards. Limiting rings I 42 are fixedly fitted onto the outer walls of the pipe at both ends of the pipe flange. These rings fit against the outer end faces of the semicircular covers 41, providing axial restraint and preventing the covers from shifting, misaligning, or falling off due to equipment vibration, thus ensuring the stability of the seal. A sealing gasket is placed between the mating surfaces of the limiting rings I 42 and the semicircular covers 41 to prevent liquid leakage through the gap. A sealing gasket is placed between the mating end faces of the two sets of semicircular covers 41, and they are secured with multiple sets of bolts 43, ensuring a tight fit between the two semicircular covers 41 and maintaining the airtightness of the liquid collection cavity, preventing leaked acid from overflowing.

[0031] One of the semicircular covers 41 has a fixed connection at its bottom to a detection tube 44, while the other semicircular cover 41 has a groove 412 on its end face. The top of the detection tube 44 is fitted into the groove 412, achieving precise communication between the liquid collection chamber and the inner cavity of the detection tube 44. This ensures that all trapped leaked liquid can be completely guided into the detection tube 44. A sealing gasket is placed between the detection tube 44 and the groove 412 to prevent liquid leakage. A fixing ring 45 is fixedly mounted on the upper part of the inner cavity of the detection tube 44. A vertical through hole is pre-drilled in the center of the fixing ring 45, and a sliding rod 46 vertically passes through the through hole of the fixing ring 45. The sliding rod 46 can slide smoothly vertically along the fixing ring 45, ensuring precise and non-deviation-free transmission. A fixing plate 47 is fixedly connected to the bottom of the sliding rod 46, and the fixing plate 47 can move vertically synchronously with the sliding rod 46. A plug 411 is installed at the bottom of the detection tube 44 through a threaded structure to achieve a tight seal at the bottom of the detection tube 44, preventing liquid leakage and structural dust ingress.

[0032] A spring I 410 is fitted around the outer ring of the sliding rod 46. The upper end of the spring I 410 abuts against the bottom end face of the fixing ring 45, and the lower end of the spring I 410 abuts against the top end face of the fixing plate 47. The preload of the spring I 410 is set to just compress the expansion block 48 in its initial state. The thrust generated by the expansion block 48 after it expands in the presence of acid is greater than the elastic force of the spring I 410, thereby pushing the fixing plate 47 and the sliding rod 46 upward. Multiple sets of expansion blocks 48 are stacked in the bottom cavity space of the fixing plate 47. The expansion blocks 48 are made of acid-expanding resin, such as cross-linked sodium polyacrylate or polyvinyl alcohol, which can absorb acidic leaked liquid and undergo volume expansion deformation after contact with acidic leaked liquid. The expansion ratio is 2-5 times, and it is resistant to strong acid corrosion. A pad 49 is sandwiched between two adjacent sets of expansion blocks 48. The pad 49 plays a role in isolating, evenly distributing liquid, and balancing the expansion force, avoiding uneven local force on a single layer of expansion block 48 and unilateral expansion jamming. Under normal conditions, spring I 410 is compressed and stores energy, continuously pressing down on the fixed plate 47 to keep the expansion block 48 in a compressed state. At the same time, the fixed ring 45 and the fixed plate 47 form a vertical limiting fit structure, which restricts the horizontal displacement and vertical sway of the fixed plate 47, assists spring I 410 in precise reset and positioning, adapts to long-term corrosive working conditions, and ensures the stability and reliability of the early warning function.

[0033] The surfaces of the fixing ring 45, fixing plate 47, and pad 49 are all perforated with rectangular openings I 415. These multiple staggered rectangular openings I 415 form a vertically penetrating liquid permeation channel. Leaking acid from inside the collection chamber can permeate downwards layer by layer along the rectangular openings I 415, evenly wetting each expansion block 48 and ensuring that multiple sets of expansion blocks 48 expand and deform synchronously and uniformly. A light-shielding film 414 is partially attached to the inner wall of the detection tube 44. The vertical area of ​​the tube wall not covered by the light-shielding film 414 forms a transparent section 413, which is the visible area for visual observation. The top of the sliding rod 46 is coated with a highly recognizable and eye-catching coating. Under normal operating conditions, the preload of the spring I 410 drives the fixed plate 47 and the sliding rod 46 to a low position, and the top of the sliding rod 46 is completely hidden at the bottom of the transparent part 413, without any warning display. When a micro-leak occurs in the flange, the acid wets the expansion block 48, causing it to expand in volume. The expansion block 48 pushes the fixed plate 47 upward, overcoming the elastic force of the spring I 410 and causing the sliding rod 46 to move upward as a whole. The area with the eye-catching coating on the top of the sliding rod 46 rises into the interior of the transparent part 413. Personnel can quickly judge the potential leakage of the flange by visual inspection, realizing early warning of hidden micro-leakage.

[0034] The power failure relief assembly 7 is mounted at the bottom of the three-way pipe 21. It serves as an emergency pressure relief and material discharge structure for extreme power failure conditions. The assembly relies on a combination of a support and fixing structure, an electromagnetic adsorption structure, and a gravity impact crushing structure to achieve automatic power failure relief and safety protection. Multiple support rods 71 ​​are evenly fixed to the inner wall of the buffer tank 2. The inner ends of these support rods 71 ​​jointly support the electromagnet block 72, ensuring its stable suspended installation and coaxial alignment with the lower three-way pipe 21. The electromagnet block 72 features a fully enclosed anti-corrosion design. The electromagnetic core is wrapped in a dense, acid-resistant protective layer, completely isolating it from acid mist and trace amounts of acidic moisture. This protective layer covers the outer surface and wiring locations of the electromagnet block 72, preventing corrosion, aging, weakening of the attraction force, and short-circuit failure of the electromagnetic components. This ensures the stability of the electromagnet block 72 during long-term operation. The electromagnet block 72 is electrically connected to an external power supply, maintaining continuous power during normal production. No separate controller is required; the attraction and release of the electromagnet block are directly controlled using the factory's power supply. A vertically fixed guide rod 73 is positioned at the bottom center of the electromagnet block 72, extending downwards into the inner cavity of the three-way pipe 21, providing guidance and constraint for the vertical sliding of the counterweight block 74.

[0035] A counterweight 74 is slidably fitted onto the outer side of the guide rod 73. During normal operation, the electromagnet block 72 generates electromagnetic attraction, stably holding the counterweight 74 to its bottom and preventing it from sliding down. The counterweight 74 adopts an integral disc-type counterweight structure with a regular and symmetrical overall shape. A precise guide hole is opened in the center, allowing for high-precision sliding contact with the guide rod 73, ensuring vertical movement without deviation or jamming. Multiple sets of rectangular openings II 78 are evenly spaced around the outer wall of the counterweight 74, penetrating both the upper and lower end faces. This regular layout of through holes ensures smooth material flow in all directions, preventing material accumulation and blockage in the pipeline due to obstruction by the counterweight structure. The bottom end face of the counterweight 74 is formed with a ring array of multiple protruding impact parts 79. The impact parts 79 are high-strength block-shaped protrusions, evenly distributed around the bottom circumference of the counterweight 74. The force is symmetrical and the impact points are uniform. During the fall, gravitational potential energy can be concentrated, and multiple points can be impacted and pressed simultaneously, which can stably and quickly break the brittle sealing plate below. The bottom end of the guide rod 73 is fixedly installed with a limiting ring II 75. The outer diameter of the limiting ring II 75 is larger than the sliding hole diameter of the counterweight 74, which can limit the bottom of the counterweight 74, prevent the counterweight 74 from sliding off the guide rod 73, and ensure the stability of the structure during operation.

[0036] The bottom end of the tee pipe 21 is threaded with a nut ring 76. A ceramic sealing plate 77 is fixedly embedded inside the nut ring 76. The ceramic sealing plate 77 is made of brittle ceramic material; when broken, the resulting fragments are small and can be discharged into the underground ice-water quenching tank 3 along with the material, preventing pipe blockage. Simultaneously, the inner wall of the bottom end of the tee pipe 21 has an anti-jamming chamfer to ensure smooth passage of fragments. Under normal conditions, the bottom opening of the tee pipe 21 is completely sealed, isolating the pipe from the underground ice-water quenching tank 3 and ensuring that material does not leak during normal production. When a sudden power outage occurs in the factory area, the electromagnet block 72 loses power simultaneously, and the electromagnetic attraction force disappears completely. The counterweight block 74 falls rapidly vertically downward along the guide rod 73 under its own gravity. The impact part 79 at the bottom hits the ceramic sealing plate 77 at high speed, using the impact of gravity to shatter the brittle ceramic sealing plate 77. The bottom channel of the three-way pipe 21 is completely connected, and the nitrated material remaining in the pipe and tank can be quickly discharged downward, falling into the underground ice water quenching pool 3 to complete low-temperature cooling and reaction termination, avoiding safety accidents such as overpressure, high temperature, and material splashing.

[0037] Example 2 Reference Figure 1 and Figure 8 This invention provides a novel technical solution: a highly selective continuous production device for o-dichlorobenzene nitration. The feed inlet of the multi-stage tubular reactor 1 is equipped with a flow self-regulating component 5, which enables purely mechanical adaptive closed-loop regulation of the feed flow rate and reaction system pressure, requiring no electrical control or instrumentation intervention, and adapting to the pressure fluctuations of the nitration reaction. This component is supported by a vertically arranged mounting cylinder 51 as the overall load-bearing base. The mounting cylinder 51 is a cylindrical, closed structure integrally formed from acid-resistant alloy, vertically fixed at the top opening of the feed pipe. The cylinder and feed pipe are sealed and welded together, ensuring a stable and secure overall structure. The inner cavity of the cylinder is a regular cylindrical hollow cavity, which can precisely accommodate and position internal deformation and transmission structures, while providing a sealed base for the internal pressure chamber, isolating it from external acid mist and environmental interference, and ensuring the long-term stable operation of the internal mechanical regulation structure.

[0038] A corrugated diaphragm 52 is sealed in the center of the inner cavity of the mounting cylinder 51. The corrugated diaphragm 52 is integrally molded from multi-layer fluoroplastic composite elastic material, featuring a ring-shaped corrugated structure. The outer ring of the corrugated diaphragm 52 is thickened and formed into a rigid sealing edge structure, which is thicker and more rigid than the main body of the diaphragm. It can stably clamp and fix itself to the sealing step on the inner wall of the mounting cylinder 51, dividing the interior of the mounting cylinder 51 into two independent sealed cavities. The main body of the corrugated diaphragm 52 features multiple continuous ring-shaped corrugations with a uniform and regular corrugated structure, possessing excellent axial flexible deformation capability. It can withstand frequent air pressure rises and falls without plastic deformation, cracking, or fatigue failure. Simultaneously, the overall material is resistant to strong acid corrosion and aging, enabling long-term adaptation to the corrosive conditions of nitrifying media. A rigid metal insert is embedded in the center of the corrugated diaphragm 52, achieving a stable and rigid connection with the transmission structure below, ensuring 100% synchronous transmission of the deformation displacement of the corrugated diaphragm 52 without displacement deviation or backlash. The membrane and the top wall of the mounting cylinder 51 form a sealed cavity 56. The cavity 56 is connected to the top gas phase space of the buffer tank 2 through the air pressure capillary tube 6, so that the real-time system gas phase pressure inside the buffer tank 2 can be transmitted to the cavity 56 in real time, and the cavity pressure is always completely synchronized with the reaction system pressure.

[0039] A vertically arranged connecting rod 53 is rigidly connected to the center of the bottom surface of the corrugated diaphragm 52 through an embedded metal insert. The connecting rod 53 extends vertically downward through the bottom of the mounting cylinder 51 and into the inside of the feed pipe, and can complete the vertical lifting and lowering action synchronously with the flexible deformation of the corrugated diaphragm 52. A support plate 58 is fixed inside the mounting cylinder 51 by welding. The bottom end of the connecting rod 53 passes through the support plate 58 and is fixedly fitted with a throttling seat 55. A wear-resistant bushing that mates with the connecting rod 53 is fixedly installed on the inner wall of the support plate 58 to reduce the friction between the connecting rod 53 and the support plate 58. The throttling seat 55 adopts an integral streamlined wedge-shaped structure, with an overall shape of a gradually changing truncated cone that is wider at the top and narrower at the bottom. The upper part is a large circular base for stable docking and fixing with the rod, and the lower part is a smoothly contracting conical throttling end. The conical surface has a uniform and smooth curvature, without sharp edges or abrupt structures. This structure can gradually and linearly change the effective flow cross-sectional area of ​​the feed pipe during vertical displacement without causing impact disturbance to the material in the pipe, achieving stable and fine-tuned flow, and avoiding turbulence and pressure oscillation caused by sudden throttling. A spring II 54 is sleeved on the outside of the connecting rod 53. The upper and lower ends of the spring II 54 abut against the bottom of the corrugated diaphragm 52 and the top of the support plate 58, respectively. The elastic support force of the spring II 54 counteracts the weight of the connecting rod 53 and the throttle seat 55. At the same time, the wear-resistant sliding fit structure between the support plate 58 and the connecting rod 53 forms a vertical auxiliary limiting constraint. The double fit always keeps the corrugated diaphragm 52 in a horizontal and flat state, ensuring the overall structure is balanced by force, preventing weight deviation, movement jamming and misadjustment, and greatly improving the flow regulation accuracy and long-term stability.

[0040] The top of the support plate 58 is provided with an air hole 57, which can achieve pressure equalization in the pipeline space below the corrugated diaphragm 52, ensuring uniform pressure transmission and stable deformation of the diaphragm, and avoiding diaphragm tilting and adjustment jamming caused by uneven pressure on one side. When the reaction system is operating stably and the internal pressure of the buffer tank 2 is within the normal range, the internal air pressure of the cavity 56 and the elastic support force of the bottom elastic structure are dynamically balanced, the corrugated diaphragm 52 remains flat and without deformation, the throttling seat 55 remains in a high position, the flow section of the feed pipe is fully open, and the material is fed normally at a stable flow rate. When the reaction inside the reactor becomes too violent and a large amount of exhaust gas is generated, causing an abnormal increase in the internal pressure of the buffer tank 2, the high-pressure gas is rapidly conducted to the cavity 56 through the air pressure capillary tube 6. The high-pressure airflow uniformly squeezes the corrugated diaphragm 52 downward, causing the middle of the corrugated diaphragm 52 to deform smoothly downward. Simultaneously, it drives the connecting rod 53 and the bottom throttling seat 55 to move downward as a whole. The wedge-shaped throttling end gradually cuts into the pipeline flow channel, gently reducing the material flow area and reducing the front feed flow rate. This reduces the continuous supply of reaction raw materials from the source and effectively suppresses the intensity of the reaction inside the pipe. As the reaction intensity gradually decreases and the system pressure gradually drops, the internal air pressure of cavity 56 decreases accordingly. The supporting force of spring II 54 drives the overall transmission and throttling structure to automatically reset, the flow area of ​​the feed pipe returns to its original state, and the feed flow rate returns to the rated state. The aforementioned sliding rod 46, fixed ring 45, fixed plate 47, connecting rod 53, and throttling seat 55 are all made of acid-resistant stainless steel or polytetrafluoroethylene and other anti-corrosion materials. Spring I 410 and spring II 54 are made of corrosion-resistant alloy springs with a fluoroplastic anti-corrosion layer on the surface. All structural components that come into contact with acidic media or are exposed to acid mist environments are made of acid-resistant and anti-corrosion materials.

[0041] During production and operation, the sliding rod 46 of the leakage monitoring component 4 should be checked regularly to see if it is reset and the expansion block 48 is malfunctioning. After each power failure emergency discharge action, the ceramic sealing plate 77 should be replaced and the counterweight 74 should be reset. It is recommended that each moving part be maintained with anti-corrosion lubrication every quarter.

[0042] The entire continuous production process of this device After the unit is officially started up, the o-dichlorobenzene feedstock and the nitrate-sulfur mixed acid feedstock are collected through the feed pipelines and enter the equipment through the feed end at the front end of the multi-stage tubular reactor 1. The material first passes through the feed station where the flow self-regulating component 5 is located. Under normal production conditions, the throttling seat 55 inside the flow self-regulating component 5 is kept in a high-level fully open state, and the material enters the tube flow channel of the multi-stage tubular reactor 1 at a stable flow rate. Relying on the mixing structure and low-temperature heat exchange structure inside the tube, the multi-stage tubular reactor 1 enables the o-dichlorobenzene and mixed acid materials to continuously undergo a uniform and mild nitration reaction, maintaining a low-temperature reaction environment throughout the process, inhibiting the formation of by-products, and improving the selectivity of the target product.

[0043] The reacted material continuously flows out from the tail end of the multi-stage tubular reactor 1 and enters the buffer tank 2 for temporary storage and pressure stabilization. The buffer tank 2 collects the trace amounts of tail gas generated during the reaction, stabilizing the internal pressure of the entire pipeline system and preventing pipeline pressure fluctuations from interfering with the upstream feed and reaction status. The material inside the buffer tank 2 is continuously and stably transported to the subsequent washing, refining, and purification processes through the bottom tee pipe 21, the open valve 22, and the extension pipe 23, achieving continuous and uninterrupted production operations.

[0044] Throughout the entire production process, the leakage monitoring components 4 at all flange connections between the multi-stage tubular reactor 1 and the buffer tank 2 are continuously monitored. When the flange seals are intact, all leakage monitoring components 4 do not activate or display any warnings. When the flanges age or the seals fail, resulting in hidden micro-leakage, the leaking acid is trapped by the cavity enclosed by the semi-circular cover 41 and gradually wets the expansion block 48 through the rectangular opening I 415, triggering the expansion and lifting action. This causes the sliding rod 46 to move upward, revealing a conspicuous warning sign, thus providing early warning of potential hazards. This facilitates timely maintenance and replacement of the sealing structure by staff, preventing the expansion of potential leakage hazards.

[0045] If an abnormally violent reaction, a large amount of exhaust gas, or an abnormally high system pressure occurs during the production process, the pressure inside the buffer tank 2 will be transmitted in real time to the cavity 56 of the flow self-regulating component 5 through the air pressure capillary tube 6. The air pressure will compress the corrugated diaphragm 52 and cause it to deform and move downward, thereby driving the throttling seat 55 to reduce the feed flow area, automatically reducing the front feed amount, reducing the continuous input of raw materials, gently suppressing the reaction intensity, and causing the system pressure to gradually drop. This achieves adaptive and stable adjustment of the production conditions without manual intervention or electrical control.

[0046] When the production process encounters an extreme failure such as a sudden power outage in the plant area and a complete failure of the electrical control system, the electromagnet block 72 of the power failure relief component 7 loses power and demagnetizes. The counterweight block 74 falls under gravity and breaks the ceramic sealing plate 77, quickly opening the relief channel at the bottom of the three-way pipe 21. All the high-risk nitrification materials remaining in the multi-stage tubular reactor 1 and buffer tank 2 are quickly discharged into the underground ice water quenching pool 3. Through rapid cooling, quenching, and termination of the exothermic reaction by low-temperature ice water, major safety risks such as overpressure explosion, material splashing, and uncontrolled high-temperature side reactions are completely avoided. After the fault is cleared and the equipment is inspected, a brand new ceramic sealing plate 77 can be replaced and all mechanical adjustment structures can be reset. The machine can then be restarted to resume continuous production. The entire set of equipment can achieve a closed-loop production operation with stable continuous production under normal conditions, adaptive control under abnormal conditions, and safety self-protection under extreme conditions.

[0047] However, as is well known to those skilled in the art, the working principles and wiring methods of the multistage tubular reactor 1 and the electromagnet block 72 are conventional methods or common knowledge, and will not be elaborated here. Those skilled in the art can make any selections according to their needs or convenience.

[0048] 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 present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A highly selective continuous production apparatus for o-dichlorobenzene nitration, characterized in that, include: A multi-stage tubular reactor (1) is provided with a buffer tank (2) at the tail end of the multi-stage tubular reactor (1). The bottom of the buffer tank (2) is provided with an underground ice water quenching pool (3). The underground ice water quenching pool (3) is buried underground. The bottom end of the buffer tank (2) is connected to a three-way pipe (21). One end of the three-way pipe (21) is connected to an extension pipe (23) through a valve (22). The bottom end of the three-way pipe (21) is provided with a power failure discharge component (7). When the power is cut off, the material in the buffer tank (2) is quickly discharged into the underground ice water quenching pool (3) for cooling. Multiple leak monitoring components (4) are respectively installed at the flange connection of the multi-stage tubular reactor (1) and the buffer tank (2). Each leak monitoring component (4) includes a detection tube (44), multiple expansion blocks (48) and a sliding rod (46) used in conjunction with the expansion blocks (48). The expansion blocks (48) absorb the leaked liquid, and after absorption, the expansion drives the sliding rod (46) to move upward, thereby monitoring the leak. The flow self-regulating component (5) is set at the feed end of the multi-stage tubular reactor (1). The flow self-regulating component (5) includes an installation cylinder (51) vertically connected to the feed pipe, a corrugated diaphragm (52) set inside the installation cylinder (51), and a throttling seat (55) connected to the bottom of the corrugated diaphragm (52). The installation cylinder (51) is connected to the buffer tank (2). The air pressure in the buffer tank (2) is used to drive the throttling seat (55) to move up and down in conjunction with the corrugated diaphragm (52) to control the flow rate.

2. The highly selective o-dichlorobenzene nitration continuous production apparatus according to claim 1, characterized in that, The power failure relief assembly (7) includes multiple support rods (71) fixed to the inner wall of the buffer tank (2). The inner ends of the multiple support rods (71) are fixed with an electromagnet block (72) coaxial with the three-way pipe (21). The bottom of the electromagnet block (72) is fixed with a guide rod (73). The bottom end of the guide rod (73) extends into the three-way pipe (21). The outer wall of the guide rod (73) is slidably fitted with a counterweight block (74). The counterweight block (74) is attracted to the bottom of the electromagnet block (72). The bottom end of the three-way pipe (21) is threaded with a nut ring (76). The nut ring (76) is fixed with a ceramic sealing plate (77) for sealing the bottom end of the three-way pipe (21). When the electromagnet block (72) is de-energized, the counterweight block (74) falls rapidly under the action of gravity and breaks the ceramic sealing plate (77).

3. The highly selective o-dichlorobenzene nitration continuous production apparatus according to claim 2, characterized in that, The outer wall of the counterweight (74) is provided with multiple rectangular openings II (78), and the bottom of the counterweight (74) is provided with multiple impact parts (79).

4. The highly selective o-dichlorobenzene nitration continuous production apparatus according to claim 3, characterized in that, The bottom of the guide rod (73) is fixedly provided with a limiting ring II (75) for limiting the counterweight (74) to prevent the counterweight (74) from detaching from the guide rod (73).

5. The highly selective o-dichlorobenzene nitration continuous production apparatus according to claim 1, characterized in that, The leakage monitoring component (4) also includes two semicircular covers (41), which are respectively fitted onto the pipes at both ends of the connecting flange. The pipes at both ends of the connecting flange are fixedly fitted with limiting rings I (42) for limiting the semicircular covers (41). The detection tube (44) is fixed to the bottom of one of the semicircular covers (41), and one end of the other semicircular cover (41) is provided with a groove (412) that matches the detection tube (44). The two semicircular covers (41) are fixedly connected by multiple bolts (43).

6. The highly selective o-dichlorobenzene nitration continuous production apparatus according to claim 5, characterized in that, A fixing ring (45) is fixed inside the detection tube (44). The sliding rod (46) slides through the top of the fixing ring (45). A fixing plate (47) is slidably provided inside the detection tube (44). The fixing plate (47) is fixed to the bottom of the sliding rod (46). A plug (411) is threaded to the bottom of the detection tube (44). A spring I (410) is sleeved on the outer wall of the sliding rod (46). The two ends of the spring I (410) abut against the bottom of the fixing ring (45) and the top of the fixing plate (47) respectively. Multiple expansion blocks (48) are located at the bottom of the fixing plate (47). The spring I (410) drives the fixing plate (47) to move downward to compress the expansion blocks (48).

7. The highly selective o-dichlorobenzene nitration continuous production apparatus according to claim 6, characterized in that, A pad (49) is provided between two adjacent expansion blocks (48). The outer walls of the fixing ring (45), fixing plate (47) and pad (49) are all provided with rectangular openings I (415). Liquid permeates downward through rectangular openings I (415) in sequence, and multiple expansion blocks (48) expand in sequence.

8. The highly selective o-dichlorobenzene nitration continuous production apparatus according to claim 7, characterized in that, The detection tube (44) is provided with a light-shielding film (414). The section of the detection tube (44) not covered by the light-shielding film (414) forms a transparent part (413). Under normal conditions, the sliding rod (46) is flush with the bottom of the transparent part (413). When leakage occurs, the sliding rod (46) extends upward into the transparent part (413). The top of the sliding rod (46) is coated with a conspicuous coating.

9. A high-selectivity o-dichlorobenzene nitration continuous production apparatus according to claim 1, characterized in that, The mounting cylinder (51) is fixedly provided with a support plate (58) located below the corrugated diaphragm (52). A connecting rod (53) is fixedly provided at the bottom center of the corrugated diaphragm (52). The connecting rod (53) slides through the top of the support plate (58). The throttling seat (55) is fixed to the bottom of the connecting rod (53). A spring II (54) is sleeved on the outer wall of the connecting rod (53). The two ends of the spring II (54) abut against the bottom of the connecting rod (53) and the top of the support plate (58) respectively. The spring II (54) drives the corrugated diaphragm (52) to overcome the gravity of the throttling seat (55) and the connecting rod (53) and remain horizontal. A cavity (56) is formed between the top of the corrugated diaphragm (52) and the mounting cylinder (51). The cavity (56) is connected to the buffer tank (2) through a pneumatic tube (6).

10. A high-selectivity o-dichlorobenzene nitration continuous production apparatus according to claim 9, characterized in that, The top of the support plate (58) is provided with air holes (57).

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