A safety protection system and method for a cyclohexanecarboxylic acid production process

Abstract

A safety protection system and method for cyclohexanecarboxylic acid production process, the system comprises benzoic acid melting kettle (1), emptying buffer tank (2), hydrogenation reaction kettle (3), hydrogen supply system (4), nitrogen supply system (5) communicated with benzoic acid melting kettle (1), emptying buffer tank (2) and hydrogenation reaction kettle (3);The production process comprises the following steps: the gas in the benzoic acid melting kettle (1) is replaced by nitrogen;The gas in the emptying buffer tank (2) is replaced by nitrogen and the emptying buffer tank (2) is purged;After the discharge of hydrogenation reaction kettle (3), the gas in the hydrogenation reaction kettle (3) is replaced by nitrogen;Check whether there is bubble in water seal tank (11) in real time, when bubble is generated at the outlet of bypass pipe (9) in water seal tank (11), replace the leaking valve.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cyclohexanecarboxylic acid production, and particularly relates to a safety protection system for a cyclohexanecarboxylic acid production process. BACKGROUND

[0002] Cyclohexanecarboxylic acid can be used for synthesizing anti-pregnancy 392 drugs and treating blood fluke new drugs such as praziquantel drugs, and can also be used as a vulcanized rubber compatibilizer, a petroleum clarifying agent, a pesticide, a dye and other organic compounds. There are many preparation methods of cyclohexanecarboxylic acid, among which the Grignard reagent method, the benzoic acid catalytic hydrogenation method, the cyclohexene-carbon monoxide addition method and the method using cyclohexanone as a raw material are the best. The reaction of synthesizing cyclohexanecarboxylic acid by catalytic hydrogenation of benzoic acid occupies a relatively important position in organic synthesis.

[0003] The production of cyclohexanecarboxylic acid by catalytic hydrogenation of benzoic acid includes the following main processes:

[0004] Hydrogen purification: remove water, oxygen, nitrogen, carbon dioxide and the like in the raw material hydrogen. The purified hydrogen is stored in a hydrogen buffer tank and then delivered to the hydrogenation section for use.

[0005] Hydrogenation reaction: molten benzoic acid reacts with hydrogen in the presence of a catalyst to generate cyclohexanecarboxylic acid. Solid benzoic acid is added to a melting kettle and heated for hot melting, and the molten material is sent to a hydrogenation reactor. Nitrogen is replaced in the hydrogenation kettle, and the catalyst is added from the solid feeding port. After the molten material is pressed in, the stirring is started, the nitrogen is replaced, and the kettle is closed. Hydrogen enters from the bottom of the reactor and reacts with the material in the kettle. The temperature in the kettle rises, and benzoic acid and excess hydrogen are subjected to hydrogenation reaction to generate cyclohexanecarboxylic acid. After the reaction is completed, the liquid product obtained by the reaction is filtered through a filter to filter out the catalyst, and the filtrate is a crude cyclohexanecarboxylic acid. The catalyst in the filter can be returned to the reactor for recycling. When the activity of the catalyst is low and cannot be used continuously, the catalyst is discharged from the bottom of the palladium-carbon filter after filtration and is contained in a container.

[0006] Rectification: the filtrate is put into a crude product storage tank and prepared for rectification. The crude cyclohexanecarboxylic acid in the crude product tank is punched into a rectification device, and vacuum rectification is performed. Light components are first removed by reflux, and then normal distillation is collected, and the remaining is kettle residue.

[0007] In the production process of cyclohexanecarboxylic acid by benzoic acid catalytic hydrogenation, the reaction temperature of the hydrogenation reactor is 140-170 DEG C, the reaction pressure is about 1.4 Mpa, and high temperature and high pressure and the constant opening valve can cause certain damage to the valve. The hydrogenation reactor device is connected with the nitrogen buffer tank and the hydrogen buffer tank, and under normal circumstances, the pressure of the nitrogen buffer tank is lower than 0.6 Mpa, the pressure of the reactor is high, and hydrogen and nitrogen are required for each hydrogenation reaction of the reactor. If the valve leaks, the hydrogen in the hydrogenation reactor will enter the nitrogen buffer tank through the nitrogen pipeline, and the nitrogen buffer tank is connected with the melting kettle, the emptying buffer tank and other equipment. Each time the machine is stopped for maintenance, nitrogen is used for replacement, and if hydrogen is filled in the nitrogen buffer tank, there is a great safety hazard.

[0008] Therefore, if a safety protection system and method for the production process of cyclohexanecarboxylic acid can be developed, the hydrogen leakage in the hydrogenation reactor into the nitrogen pipeline can be detected in time, and the hydrogen entering the nitrogen system can be avoided, so that the safety of production can be improved, and the development of the production of cyclohexanecarboxylic acid by benzoic acid catalytic hydrogenation can be greatly promoted. SUMMARY

[0009] In view of the shortcomings of the prior art, one of the purposes of the present application is to provide a safety protection system for the production process of cyclohexanecarboxylic acid, and the second purpose of the present application is to provide a safety protection method for the production process of cyclohexanecarboxylic acid, which uses nitrogen to replace the gas in the system, can detect the hydrogen leakage in the hydrogenation reactor into the nitrogen pipeline in time, can avoid the hydrogen entering the nitrogen system, and can improve the safety of production.

[0010] In order to solve the above technical problems, on the one hand, the present application provides a safety protection system for the production process of cyclohexanecarboxylic acid, which comprises a benzoic acid melting kettle, an emptying buffer tank connected with the discharge port of the benzoic acid melting kettle through a pipeline, a hydrogenation reactor connected with the discharge port of the emptying buffer tank through a feed port, a hydrogen supply system connected with the hydrogenation reactor, and a nitrogen supply system connected with the benzoic acid melting kettle, the emptying buffer tank and the hydrogenation reactor. The nitrogen supply system has a nitrogen buffer tank connected with the benzoic acid melting kettle, the emptying buffer tank and the hydrogenation reactor through a pipeline, a first nitrogen valve and a second nitrogen valve arranged on the pipeline connecting the nitrogen buffer tank with the hydrogenation reactor, a bypass pipe connected with the pipeline between the first nitrogen valve and the second nitrogen valve, a vent valve arranged on the bypass pipe, a water seal tank connected with the bottom of the bypass pipe, a third nitrogen valve arranged on the pipeline connecting the benzoic acid melting kettle with the nitrogen buffer tank, and a fourth nitrogen valve arranged on the pipeline connecting the emptying buffer tank with the nitrogen buffer tank.

[0011] As a further improved technical solution, the safety protection system for the production process of cyclohexanecarboxylic acid provided by the present application further has a hydrogen sensor arranged above the water seal tank.

[0012] As a further improved technical solution, the safety protection system for the cyclohexanecarboxylic acid production process provided by the present application further has a smoke alarm arranged above the water seal tank.

[0013] As a further improved technical solution, the safety protection system for the cyclohexanecarboxylic acid production process provided by the present application further has a first medium inlet communicated with the benzoic acid melting kettle, the emptying buffer tank and the hydrogenation kettle through pipelines respectively, a displacing gas cooler, a collector communicated with the first medium outlet, and a filter arranged at a gas discharge port of the collector.

[0014] In order to solve the above technical problems, on the other hand, the present application provides a safety protection method for a cyclohexanecarboxylic acid production process, which uses the safety protection system for the cyclohexanecarboxylic acid production process, and the production process comprises the following steps:

[0015] Before adding benzoic acid into the benzoic acid melting kettle, the gas in the benzoic acid melting kettle is replaced by nitrogen; after adding the benzoic acid, the gas in the benzoic acid melting kettle is replaced by nitrogen again, and then the benzoic acid melting kettle is closed and heated to melt the benzoic acid;

[0016] Before putting the melted benzoic acid into the emptying buffer tank, the gas in the emptying buffer tank is replaced by nitrogen and the emptying buffer tank is purged;

[0017] Before discharging the hydrogenation kettle, the valve on the pipeline of the hydrogen supply system into the hydrogenation kettle is closed; after discharging the hydrogenation kettle, the emptying valve is closed, the first nitrogen valve and the second nitrogen valve are opened, and the gas in the hydrogenation kettle is replaced by nitrogen;

[0018] During the hydrogenation reaction process of the hydrogenation kettle, the first nitrogen valve and the second nitrogen valve are closed, and the emptying valve is opened; whether the gas bubble is generated in the water seal tank is checked in real time; when the gas bubble is generated at the outlet of the bypass pipe of the water seal tank, it is further determined whether the first nitrogen valve or the second nitrogen valve leaks, and the leaking valve is replaced.

[0019] As a further improved technical solution, the safety protection method for the cyclohexanecarboxylic acid production process provided by the present application further has that the safety protection system for the cyclohexanecarboxylic acid production process further has a first medium inlet communicated with the benzoic acid melting kettle, the emptying buffer tank and the hydrogenation kettle through pipelines respectively, a displacing gas cooler, a collector communicated with the first medium outlet, and a filter arranged at a gas discharge port of the collector; the gas and purging material displaced from the benzoic acid melting kettle, the emptying buffer tank or the hydrogenation kettle are cooled by the displacing gas cooler and then discharged into the collector; the collector collects solid materials, and the gas is filtered by the filter and then discharged.

[0020] Where there is no conflict, the aforementioned improved technical solutions can be implemented individually or in combination.

[0021] The technical solution provided by this invention uses a nitrogen replacement system to detect hydrogen leakage into the nitrogen pipeline in a timely manner, thereby preventing hydrogen from entering the nitrogen system and improving production safety. Attached Figure Description

[0022] The accompanying drawings are provided to further illustrate the invention and form part of this application. Illustrative embodiments of the invention and their descriptions are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0023] Figure 1 This is a structural diagram of a safety protection system used in the production process of cyclohexanecarboxylic acid, as an example. Implementation

[0024] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0025] like Figure 1 The safety protection system shown for the cyclohexane production process includes a benzoic acid melting vessel 1, an emptying buffer tank 2 connected to the outlet of the benzoic acid melting vessel 1 via a pipeline, a hydrogenation reactor 3 whose inlet is connected to the outlet of the emptying buffer tank 2, a hydrogen supply system 4 connected to the hydrogenation reactor 3, and a nitrogen supply system 5 connected to the benzoic acid melting vessel 1, the emptying buffer tank 2, and the hydrogenation reactor 3. The nitrogen supply system 5 includes a nitrogen buffer tank 6 connected to the benzoic acid melting vessel 1, the venting buffer tank 2, and the hydrogenation reactor 3 via pipelines; a first nitrogen valve 7 and a second nitrogen valve 8 installed on the pipeline connecting the nitrogen buffer tank 6 and the hydrogenation reactor 3; a bypass pipe 9 connected to the pipeline between the first nitrogen valve 7 and the second nitrogen valve 8; a vent valve 10 installed on the bypass pipe 9; a water seal trough 11 connected to the bottom of the bypass pipe 9; a third nitrogen valve 12 installed on the pipeline connecting the benzoic acid melting vessel 1 and the nitrogen buffer tank 6; and a fourth nitrogen valve 13 installed on the pipeline connecting the venting buffer tank 2 and the nitrogen buffer tank 6.

[0026] The production process includes the following steps:

[0027] Before adding benzoic acid into the benzoic acid melting vessel 1, the gas inside the benzoic acid melting vessel 1 is replaced with nitrogen; after adding benzoic acid, the gas inside the benzoic acid melting vessel 1 is replaced with nitrogen again, and then the benzoic acid melting vessel 1 is closed and heated to melt the benzoic acid.

[0028] Before adding molten benzoic acid into the venting buffer tank 2, the gas inside the venting buffer tank 2 is replaced with nitrogen and the venting buffer tank 2 is purged.

[0029] Before the hydrogenation reactor 3 is discharged, the valve on the pipeline of the hydrogen supply system 4 into the hydrogenation reactor 3 is closed, and after the hydrogenation reactor 3 is discharged, the vent valve 10 is closed, the first nitrogen valve 7 and the second nitrogen valve 8 are opened, and the gas in the hydrogenation reactor 3 is replaced out by nitrogen;

[0030] During the hydrogenation reaction of the hydrogenation reactor 3, the first nitrogen valve 7 and the second nitrogen valve 8 are closed, and the vent valve 10 is opened; whether bubbles are generated in the water seal tank 11 is checked in real time, when bubbles are generated at the outlet of the bypass pipe 9 in the water seal tank 11, whether the first nitrogen valve 7 or the second nitrogen valve 8 leaks is further detected and determined, and the leaking valve is replaced.

[0031] Before and after the benzene acid melting kettle 1 is charged, the gas in the melting kettle is replaced by nitrogen, which is beneficial to reduce the mixing of impurities and avoid the contact of benzene acid with oxygen. Before and after the emptying buffer tank 2 receives the melted benzene acid, the gas in the melting kettle is replaced by nitrogen, which is beneficial to reduce the mixing of impurities and avoid the contact of benzene acid with oxygen.

[0032] During the operation of the hydrogenation reactor 3, the reaction pressure is about 1.4 Mpa, the pressure in the nitrogen buffer tank 6 is relatively low, generally not more than 0.6 Mpa, and in the traditional installation mode, when the valve on the nitrogen pipeline from the nitrogen buffer tank 6 to the hydrogenation reactor 3 leaks, hydrogen will enter the nitrogen buffer tank 6, thereby affecting the safety of the system. In the technical scheme provided by the present application, during the hydrogenation reaction of the hydrogenation reactor 3, the first nitrogen valve 7 is in a closed state, preventing the material in the hydrogenation reactor 3 from leaking out; the second nitrogen valve 8 is also closed, preventing the nitrogen in the nitrogen buffer tank 6 from being discharged outward; and the vent valve 10 is opened, if the first nitrogen valve 7 or the second nitrogen valve 8 leaks, the leaked material enters the water seal tank 11, bubbles are generated in the water seal tank 11, and the leakage can be found in time. During production, after the hydrogenation reactor 3 is discharged, the gas in the reactor needs to be replaced by nitrogen, when the gas in the hydrogenation reactor 3 needs to be replaced by nitrogen, the valve on the pipeline of the hydrogen supply system 4 into the hydrogenation reactor 3 is closed, the vent valve 10 is closed, the first nitrogen valve 7 and the second nitrogen valve 8 are opened, and nitrogen enters the hydrogenation reactor 3 to replace the gas in the reactor. When more bubbles are generated in the water seal tank 11, it is detected that the first nitrogen valve 7 or the second nitrogen valve 8 leaks, further detection determines whether the first nitrogen valve 7 or the second nitrogen valve 8 leaks, and then the leaking valve is replaced. In the normal production process, the water level in the water seal tank 11 submerges the bottom end of the bypass pipe 9, the vent valve 10 is closed when nitrogen is replaced, after the combustible gas is qualified after the nitrogen replacement for two times, the first nitrogen valve 7 and the second nitrogen valve 8 are closed, and the vent valve 10 is opened, whether the valve exists internal leakage is determined by observing whether bubbles exist in the water seal tank 11, and if there is internal leakage, the valve needs to be replaced in time.

[0033] The technical solution provided by this invention can effectively prevent hydrogen from entering the nitrogen system from the hydrogenation reactor 3, eliminating potential safety hazards. Because it can promptly detect hydrogen leaks in the hydrogenation reactor 3, it helps to reduce hydrogen consumption and production costs.

[0034] As one example, such as Figure 1 As shown, based on the aforementioned basic solution, the safety protection system for the cyclohexane carboxylic acid production process provided by this invention also includes a hydrogen sensor 14 installed above the water seal tank 11. When hydrogen leakage occurs, the hydrogen content in the environment will rise. When the hydrogen sensor 14 detects that the hydrogen content in the environment exceeds the standard, it will issue an alarm and other relevant information, further improving the safety of the system.

[0035] As one example, such as Figure 1 As shown, based on the aforementioned basic solution, the safety protection system for the cyclohexane carboxylic acid production process provided by this invention also includes a smoke detector 15 installed above the water seal tank 11. When the hydrogen content in the environment exceeds the standard and a fire alarm occurs, the smoke detector 15 will promptly issue an alarm message.

[0036] As one example, such as Figure 1 As shown, based on the aforementioned basic scheme, the safety protection system for the cyclohexane carboxylic acid production process provided by this invention further includes a displacement gas cooler 16, with a first medium inlet connected via pipelines to the benzoic acid melting vessel 1, the venting buffer tank 2, and the hydrogenation reactor 3, respectively; a collector 17 connected to the first medium outlet; and a filter 18 installed at the gas discharge port of the collector 17. The gas and purge material displaced from the benzoic acid melting vessel 1, the venting buffer tank 2, or the hydrogenation reactor 3 are cooled by the displacement gas cooler 16 and then discharged into the collector 17. The collector 17 collects solids, and the gas is filtered by the filter 18 before being discharged. The benzoic acid-containing gas, after cooling, is collected by the collector 17, which reduces environmental pollution and saves on the amount of benzoic acid used.

[0037] The above description is merely a preferred embodiment of the present invention and does not limit the invention in any way. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A safety protection method for the production process of cyclohexane carboxylic acid, using a safety protection system for the production process of cyclohexane carboxylic acid, the safety protection system for the production process of cyclohexane carboxylic acid includes a benzoic acid melting kettle (1), an emptying buffer tank (2) connected to the outlet of the benzoic acid melting kettle (1) via a pipeline, a hydrogenation reactor (3) with its inlet connected to the outlet of the emptying buffer tank (2), a hydrogen supply system (4) connected to the hydrogenation reactor (3), and a nitrogen supply system (5) connected to the benzoic acid melting kettle (1), the emptying buffer tank (2), and the hydrogenation reactor (3); the nitrogen supply system (5) has a nitrogen buffer tank (6) connected to the benzoic acid melting kettle (1), the emptying buffer tank (2), and the hydrogenation reactor (3) via a pipeline, and is arranged between the nitrogen buffer tank (6) and the hydrogenation reactor (3). The system comprises: a first nitrogen valve (7) and a second nitrogen valve (8) connected to the pipeline; a bypass pipe (9) connecting the first nitrogen valve (7) and the second nitrogen valve (8); a vent valve (10) installed on the bypass pipe (9); a water seal tank (11) connected to the bottom of the bypass pipe (9); a third nitrogen valve (12) installed on the pipeline connecting the benzoic acid melting vessel (1) and the nitrogen buffer tank (6); a fourth nitrogen valve (13) installed on the pipeline connecting the vent buffer tank (2) and the nitrogen buffer tank (6); a displacement gas cooler (16) connected to the benzoic acid melting vessel (1), the vent buffer tank (2), and the hydrogenation reactor (3) respectively via a pipeline for the first medium inlet; a collector (17) connected to the first medium outlet; and a filter (18) installed at the gas outlet of the collector (17). The production process includes the following steps: Before adding benzoic acid into the benzoic acid melting vessel (1), the gas inside the benzoic acid melting vessel (1) is replaced with nitrogen; after adding benzoic acid, the gas inside the benzoic acid melting vessel (1) is replaced with nitrogen again, and then the benzoic acid melting vessel (1) is closed and heated to melt the benzoic acid. Before putting molten benzoic acid into the venting buffer tank (2), the gas in the venting buffer tank (2) is replaced with nitrogen and the venting buffer tank (2) is purged. Before discharging the hydrogenation reactor (3), close the valve on the pipeline from the hydrogen supply system (4) to the hydrogenation reactor (3). After discharging the hydrogenation reactor (3), close the vent valve (10), open the first nitrogen valve (7) and the second nitrogen valve (8), and use nitrogen to replace the gas in the hydrogenation reactor (3). During the hydrogenation reaction in the hydrogenation reactor (3), the first nitrogen valve (7) and the second nitrogen valve (8) are closed, and the vent valve (10) is opened. Check in real time whether there are bubbles in the water seal tank (11). When bubbles are generated at the outlet of the bypass pipe (9) in the water seal tank (11), further detection is performed to determine whether the first nitrogen valve (7) or the second nitrogen valve (8) is leaking, and the leaking valve is replaced. The gas and purge material displaced from the benzoic acid melting vessel (1), the empty buffer tank (2) or the hydrogenation reactor (3) are cooled by the displacement gas cooler (16) and then discharged into the collector (17). The collector (17) collects the solids, and the gas is filtered by the filter (18) and then discharged.

2. The safety protection method for the production process of cyclohexanecarboxylic acid according to claim 1, characterized in that, The safety protection system for the production process of cyclohexane carboxylic acid also has a hydrogen sensor (14) installed above the water seal tank (11).

3. The safety protection method for the cyclohexane carboxylic acid production process according to claim 1, characterized in that, The safety protection system for the production process of cyclohexane also includes a smoke detector (15) installed above the water seal tank (11).

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