A horizontal continuous reactor for preparing cyclic carbonate by urea process

Abstract

The present invention relates to the field of urea method for preparing cyclic carbonate, and specifically discloses a horizontal continuous reactor used for preparing cyclic carbonate by urea method, which solves the technical problem that the reaction equipment using multiple kettle reactors connected by pipelines in the current process of preparing cyclic carbonate is prone to increase of side reactions. The horizontal continuous reactor of the present invention comprises: a horizontal reactor, comprising a plurality of sub-reactors connected and arranged in sequence in the horizontal direction, the bottom of the sub-reactors is arc-shaped, the horizontal reactor is provided with a heating jacket and a cooling coil, and the top of the horizontal reactor is provided with a plurality of gas phase pipes; a stirring assembly, comprising a plurality of arc-shaped stirring paddles close to the bottom of the sub-reactor, the arc of the arc-shaped stirring paddles being consistent with the arc of the bottom of the sub-reactor; a first nitrogen blowing assembly, comprising a plurality of nitrogen blowing pipes arranged at intervals along the circumference of the horizontal reactor. The present invention can reduce the pipeline setting, reduce the generation of side reactions, increase the ammonia discharge rate, and improve the yield.

Description

Technical Field

[0001] The invention relates to the technical field of devices for preparing cyclic carbonate by urea method, and in particular to a horizontal continuous reactor used for preparing cyclic carbonate by urea method. Background Art

[0002] At present, in the process of preparing cyclic carbonate by urea method, it is usually necessary to use multiple kettle reactors connected by pipelines. This method is more common in industrial production, because through the series operation of multiple reactors, the reaction conditions can be better controlled, the efficiency of the reaction and the purity of the product can be improved. For example, patent CN104059047A discloses a continuous reaction process for synthesizing cyclic carbonate from urea, which regulates the liquid level in each kettle reactor by accurately controlling the circulation extraction ratio, thereby effectively avoiding the energy consumption and unstable product quality caused by frequent heating and cooling during intermittent operation of a single kettle. This method not only improves the efficiency of energy utilization, but also significantly improves the quality consistency of the product.

[0003] Although this multi-tank reactor can meet the reaction requirements to a certain extent, its complex design and operation also bring some challenges. First, the connection of multiple reactors inevitably requires the use of multiple pipelines. In the process of transferring materials from one reactor to another, the residence time and temperature changes in the pipeline may trigger side reactions, leading to an increase in by-products, which in turn affects the purity and yield of the final product. Secondly, the flow of materials in the pipeline may make it difficult to discharge ammonia in the pipeline, especially when the pipeline is long or the design is unreasonable. The accumulation of ammonia will not only affect the efficiency of the reaction, but also may bring safety hazards.

[0004] In addition, the complexity of multi-tank reactors is also reflected in equipment maintenance and operation control. The connection of multiple reactors and pipelines increases the complexity of the system, requiring more sophisticated control strategies and higher operating skills. This not only increases the initial investment and operating costs of the equipment, but may also increase the difficulty of maintenance and failure rate in long-term operation. Summary of the invention

[0005] The purpose of the present invention is to provide a horizontal continuous reactor for preparing cyclic carbonates by urea method, so as to solve the technical problem that in the current process of preparing cyclic carbonates by urea method, a reaction device connected with multiple kettle reactors is used, which easily leads to an increase in side reactions.

[0006] The present invention provides a horizontal continuous reactor for preparing cyclic carbonate by urea method, comprising: a horizontal reactor, comprising a plurality of interconnected sub-reactors arranged in sequence in a horizontal direction, the bottom of the sub-reactors being arc-shaped, the horizontal reactor being provided with a heating jacket and a cooling coil, the sub-reactor located at the head end of the plurality of sub-reactors being provided with a feed pipe, the sub-reactor located at the tail end being provided with a discharge pipe, and the top of the horizontal reactor being provided with a plurality of gas phase pipes; a stirring assembly being provided with a plurality of arc-shaped stirring paddles close to the bottom of the sub-reactors, the arc of the arc-shaped stirring paddles being consistent with the arc of the bottom of the sub-reactors; and a first nitrogen blowing assembly comprising a plurality of nitrogen blowing pipes arranged at intervals along the circumference of the horizontal reactor.

[0007] According to one embodiment of the present invention, the distance between the lowest point of the arc-shaped stirring paddle and the lowest point of the bottom of the sub-reactor is in the range of 5 mm to 30 mm.

[0008] According to one embodiment of the present invention, any two of the sub-reactors are connected via a flow guide pipe.

[0009] According to one embodiment of the present invention, a valve is provided on the flow guide pipe.

[0010] According to one embodiment of the present invention, the height of the flow guide pipe is lower than the highest height of the curved surface of the sub-reactor.

[0011] According to one embodiment of the present invention, the stirring assembly includes a stirring motor, a stirring main shaft, a bevel gear assembly, a stirring secondary shaft and an arc-shaped stirring paddle. The stirring main shaft is arranged in a horizontal direction and is connected to the stirring secondary shaft arranged in a vertical direction through the bevel gear assembly. The bottom end of the stirring secondary shaft is connected to the arc-shaped stirring paddle, and the stirring motor is connected to the stirring main shaft.

[0012] According to one embodiment of the present invention, the gas phase pipe is connected to the vacuum system via a condenser.

[0013] According to one embodiment of the present invention, it further comprises a plurality of nitrogen blowing auxiliary pipes directed toward the bottom of the sub-reactor.

[0014] According to one embodiment of the present invention, the horizontal reactor is also provided with a pressure measuring port, a side temperature port and a liquid level gauge interface.

[0015] The technical solution of the present invention has at least the following advantages and beneficial effects:

[0016] (1) The horizontal reactor of the present invention is composed of a plurality of sub-reactors, and each sub-reactor does not need to be connected by pipelines and pumps, but flows from one reactor to another reactor by overflow. In the process of preparing cyclic carbonate by urea method, the occurrence of side reactions can be significantly reduced by reducing pipelines. Ammonia is extracted together through the exhaust pipe of the horizontal reactor.

[0017] (2) A nitrogen blowing pipe is provided at the bottom of each reactor in the lower part of the horizontal reactor, which can increase the overflow rate of ammonia and reduce the generation of side reactions.

[0018] (3) In order to solve the problem that part of the catalyst remaining at the bottom of the horizontal reactor is difficult to flow into the next sub-reactor through overflow, the present invention sets a guide pipe below the top of the arc-shaped surface of the sub-reactor. On the one hand, the catalyst increases the mixing effect with the material under the action of nitrogen blowing, ensuring that part of the catalyst can flow into the next reactor through overflow; on the other hand, through the nitrogen blowing auxiliary pipe, the bottom catalyst flows from the guide pipe to the next sub-reactor under the action of pushing.

[0019] (4) The stirring assembly of the present invention includes a plurality of arc-shaped stirring paddles. Stirring can ensure uniform distribution of reactants in the reactor, make reactants fully contact, prevent local concentration from being too high or too low, ensure stable reaction, and thus improve reaction rate and conversion rate. The curvature of the arc-shaped stirring paddle matches the bottom of the sub-reactor, and a thin film can be formed at the bottom of each sub-reactor. This film can increase the contact area between reactants and catalysts, thereby improving mass transfer efficiency, helping to accelerate the diffusion and mass transfer process of reactants, and further improving reaction rate. Furthermore, the film formed by stirring can effectively disperse heat and avoid local overheating. Through uniform stirring, the reaction temperature can be better controlled to ensure that the reaction is carried out within an appropriate temperature range. In addition, the formation of this film also helps to quickly release ammonia and reduce the accumulation of ammonia in the reaction system, thereby reducing safety risks and improving product purity.

[0020] (5) The condenser and vacuum system provided in the present invention help to remove the by-product ammonia during the reaction process, making the product quality more reliable.

[0021] (6) The present invention has reasonable design, simple structure and good practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 This is a schematic diagram of the structure of a horizontal continuous reactor for preparing cyclic carbonates by the urea process provided in Example 1 of the present invention.

[0024] Figure 2A schematic diagram of the side view of a horizontal continuous reactor for preparing cyclic carbonates by the urea process provided in Example 2 of the present invention.

[0025] Reference numerals:

[0026] 100, horizontal reactor; 110, sub-reactor; 120, heating jacket; 130, cooling coil; 140, pressure measuring port; 150, side temperature port; 160, liquid level gauge interface; 170, feed port; 180, discharge port;

[0027] M, stirring motor; 210, stirring main shaft; 220, bevel gear assembly; 230, stirring secondary shaft; 240, arc stirring paddle;

[0028] 310, condenser; 320, gas phase pipe;

[0029] 400, flow guide pipe; 410, valve;

[0030] 500. Nitrogen inflation tube. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0032] Example 1

[0033] Embodiment 1 of the present invention provides a horizontal continuous reactor for preparing cyclic carbonate by urea process, so as to reduce pipeline setting and increase ammonia discharge rate.

[0034] See also Figure 1 as well as Figure 2The horizontal continuous reactor for preparing cyclic carbonate by urea method provided by the embodiment of the present invention comprises: a horizontal reactor 100, comprising a plurality of interconnected sub-reactors 110 arranged in sequence along the horizontal direction, wherein the sub-reactors 110 do not need to be connected by pipelines and pumps, and the material enters from one reactor to another reactor by overflow, and the bottom of the sub-reactor 110 is arc-shaped, and the horizontal reactor 100 is provided with a heating jacket 120 and a cooling coil 130 to control the reaction temperature and ensure that the reaction is carried out within a suitable temperature range, and the plurality of sub-reactors 110, the sub-reactor 110 located at the head end is provided with a feed inlet 170, and the sub-reactor 110 located at the end is provided with a discharge port 180. The top of the horizontal reactor 100 is provided with a plurality of gas phase pipes 320 for extracting ammonia generated during the reaction process; the stirring assembly is provided with a plurality of arc-shaped stirring paddles 240 close to the bottom of the sub-reactor 110, and the curvature of the arc-shaped stirring paddles 240 is consistent with the curvature of the bottom of the sub-reactor 110; the first nitrogen blowing assembly includes a plurality of nitrogen blowing pipes 500 arranged at intervals along the circumference of the horizontal reactor 100.

[0035] In this embodiment, the lowest point of the arc-shaped stirring paddle 240 and the lowest point of the bottom of the sub-reactor 110 are spaced in the range of 5mm-30mm. Stirring can ensure the uniform distribution of the reactants in the reactor, make the reactants fully contact, prevent the local concentration from being too high or too low, ensure the stable progress of the reaction, and thus improve the reaction rate and conversion rate. The arc of the arc-shaped stirring paddle 240 matches the bottom of the sub-reactor 110, and a thin film can be formed at the bottom of each sub-reactor 110. This film can increase the contact area between the reactants and the catalyst, thereby improving the mass transfer efficiency, helping to accelerate the diffusion and mass transfer process of the reactants, and further improving the reaction rate. The film formed by stirring can effectively disperse heat and avoid local overheating. Through uniform stirring, the reaction temperature can be better controlled to ensure that the reaction is carried out within a suitable temperature range. The formation of this film also helps to quickly release ammonia and reduce the accumulation of ammonia in the reaction system, thereby reducing safety risks and improving the purity of the product.

[0036] In this embodiment, any two of the sub-reactors 110 are connected by a draft tube 400. On the one hand, the catalyst increases the mixing effect with the material under the action of the nitrogen blowing tube 500, ensuring that a part of the catalyst can enter the next reactor body through overflow; on the other hand, the bottom catalyst flows from the draft tube 400 to the next sub-reactor 110. In this embodiment, along the material moving direction, the previous sub-reactor 110 is connected to the next sub-reactor 110 through the draft tube 400, and the height of the nozzle of the draft tube 400 connected to the previous sub-reactor 110 is higher than the height of the nozzle connected to the next sub-reactor 110.

[0037] In this embodiment, a valve 410 is provided on the flow guide pipe 400 .

[0038] In this embodiment, the height of the flow guide pipe 400 is lower than the highest height of the curved surface of the sub-reactor 110 .

[0039] In this embodiment, the stirring assembly includes a stirring motor M, a stirring main shaft 210, a bevel gear assembly 220, a stirring sub-shaft 230 and an arc-shaped stirring paddle 240. The stirring main shaft 210 is arranged in a horizontal direction and is connected to the stirring sub-shaft 230 arranged in a vertical direction through the bevel gear assembly 220. The bottom end of the stirring sub-shaft 230 is connected to the arc-shaped stirring paddle 240. The bevel gear assembly 220 includes a first bevel gear connected to the stirring main shaft 210 and a second bevel gear connected to the stirring sub-shaft 230. The first bevel gear and the second bevel gear are meshed. The stirring main shaft 210 and the stirring sub-shaft 230 are arranged vertically to each other. The stirring motor M is connected to the stirring main shaft 210.

[0040] In this embodiment, the gas phase pipe 320 is connected to the vacuum system through the condenser 310, which helps to remove the by-product ammonia in the reaction process.

[0041] In this embodiment, the horizontal reactor 100 is also provided with a pressure measuring port 140, a side temperature port 150 and a liquid level gauge interface 160 to monitor the reaction conditions in real time. The pressure measuring port 140 is used to monitor the pressure of the horizontal reactor 100, the temperature measuring port is used to monitor the temperature of the horizontal reactor 100, and the liquid level gauge interface 160 is used to monitor the liquid level height in the horizontal reactor 100.

[0042] In this embodiment, the bevel gear assembly 220 is provided with an anti-corrosion housing.

[0043] The following is a detailed description of the use of the horizontal continuous reactor for preparing cyclic carbonate by urea process of the present invention:

[0044] In the process of preparing cyclic carbonate by urea method, the mixed solution of catalyst, urea and diol enters the first sub-reactor 110 of the horizontal reactor 100 from the feed port 170. The stirring assembly works continuously to ensure that the reactants are fully mixed and promote the complete reaction. With the continuous addition of the mixed solution, the material flows from the previous reactor to the next reactor through overflow, and each subsequent reactor continues to control the reaction conditions through the corresponding heating jacket 120 and cooling coil 130 to ensure the smooth progress of the reaction.

[0045] During the entire reaction process, nitrogen is continuously blown in through the nitrogen blowing pipe 500 to promote the escape of ammonia in the mixed solution and reduce the accumulation of ammonia in the reaction system. At the same time, the catalyst at the bottom smoothly enters the next sub-reactor 110 through the guide pipe 400, ensuring the uniform distribution of the catalyst in each reactor, further improving the reaction efficiency and the purity of the product.

[0046] Example 2

[0047] Embodiment 2 of the present invention provides a horizontal continuous reactor for preparing cyclic carbonate by urea process, so as to reduce pipeline setting and increase ammonia discharge rate.

[0048] The horizontal continuous reactor for preparing cyclic carbonate by urea method provided in the embodiment of the present invention is different from that in Embodiment 1 only in that, in the present embodiment, it also includes a plurality of nitrogen blowing auxiliary pipes toward the bottom of the sub-reactor 110, which are used to push the bottom catalyst into the next sub-reactor 110.

[0049] The embodiments of the present invention have at least the following advantages:

[0050] (1) The horizontal reactor of the present invention is composed of a plurality of sub-reactors, and each sub-reactor does not need to be connected by pipelines and pumps, but flows from one reactor to another reactor by overflow. In the process of preparing cyclic carbonate by urea method, the occurrence of side reactions can be significantly reduced by reducing pipelines. Ammonia is extracted together through the exhaust pipe of the horizontal reactor.

[0051] (2) A nitrogen blowing pipe is provided at the bottom of each reactor in the lower part of the horizontal reactor, which can increase the overflow rate of ammonia and reduce the generation of side reactions.

[0052] (3) In order to solve the problem that part of the catalyst remaining at the bottom of the horizontal reactor is difficult to flow into the next sub-reactor through overflow, the present invention sets a guide pipe below the top of the arc-shaped surface of the sub-reactor. On the one hand, the catalyst increases the mixing effect with the material under the action of nitrogen blowing, ensuring that part of the catalyst can flow into the next reactor through overflow; on the other hand, through the nitrogen blowing auxiliary pipe, the bottom catalyst flows from the guide pipe to the next sub-reactor under the action of pushing.

[0053] (4) The stirring assembly of the present invention includes a plurality of arc-shaped stirring paddles. Stirring can ensure uniform distribution of reactants in the reactor, make reactants fully contact, prevent local concentration from being too high or too low, ensure stable reaction, and thus improve reaction rate and conversion rate. The curvature of the arc-shaped stirring paddle matches the bottom of the sub-reactor, and a thin film can be formed at the bottom of each sub-reactor. This film can increase the contact area between reactants and catalysts, thereby improving mass transfer efficiency, helping to accelerate the diffusion and mass transfer process of reactants, and further improving reaction rate. Furthermore, the film formed by stirring can effectively disperse heat and avoid local overheating. Through uniform stirring, the reaction temperature can be better controlled to ensure that the reaction is carried out within an appropriate temperature range. In addition, the formation of this film also helps to quickly release ammonia and reduce the accumulation of ammonia in the reaction system, thereby reducing safety risks and improving product purity.

[0054] (5) The condenser and vacuum system provided in the present invention help to remove the by-product ammonia during the reaction process, making the product quality more reliable.

[0055] (6) The present invention has reasonable design, simple structure and good practicality.

[0056] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A horizontal continuous reactor for preparing cyclic carbonate by urea process, characterized in that: include: A horizontal reactor, comprising a plurality of interconnected sub-reactors arranged in sequence in the horizontal direction, wherein the bottom of the sub-reactors is arc-shaped, the horizontal reactor is provided with a heating jacket and a cooling coil, the sub-reactor at the head end of the plurality of sub-reactors is provided with a feed pipe, the sub-reactor at the end end is provided with a discharge pipe, and the top of the horizontal reactor is provided with a plurality of gas phase pipes; A stirring assembly, provided with a plurality of arc-shaped stirring paddles close to the bottom of the sub-reactor, wherein the curvature of the arc-shaped stirring paddles is consistent with the curvature of the bottom of the sub-reactor; The first nitrogen blowing assembly includes a plurality of nitrogen blowing pipes spaced apart along the circumference of the horizontal reactor.

2. The horizontal continuous reactor for preparing cyclic carbonate by urea process according to claim 1, characterized in that: The distance between the lowest point of the arc-shaped stirring paddle and the lowest point of the bottom of the sub-reactor is in the range of 5mm-30mm.

3. The horizontal continuous reactor for preparing cyclic carbonate by urea process according to claim 1, characterized in that: Any two of the sub-reactors are connected via a flow guide pipe.

4. The horizontal continuous reactor for preparing cyclic carbonate by urea process according to claim 3, characterized in that: The flow guide pipe is provided with a valve.

5. The horizontal continuous reactor for preparing cyclic carbonate by urea process according to claim 3, characterized in that: The height of the flow guide pipe is lower than the highest height of the arc-shaped surface of the sub-reactor.

6. The horizontal continuous reactor for preparing cyclic carbonate by urea process according to any one of claims 1 to 5, characterized in that: The stirring assembly includes a stirring motor, a stirring main shaft, a bevel gear assembly, a stirring secondary shaft and an arc-shaped stirring paddle. The stirring main shaft is arranged in a horizontal direction and is connected to a stirring secondary shaft arranged in a vertical direction through a bevel gear assembly. The bottom end of the stirring secondary shaft is connected to the arc-shaped stirring paddle, and the stirring motor is connected to the stirring main shaft.

7. The horizontal continuous reactor for preparing cyclic carbonate by urea process according to any one of claims 1 to 5, characterized in that: The gas phase pipe is connected to the vacuum system through a condenser.

8. The horizontal continuous reactor for preparing cyclic carbonate by urea process according to any one of claims 1 to 5, characterized in that: It also includes a plurality of nitrogen blowing auxiliary pipes directed toward the bottom of the sub-reactor.

9. The horizontal continuous reactor for preparing cyclic carbonate by urea process according to any one of claims 1 to 5, characterized in that: The horizontal reactor is also provided with a pressure measuring port, a side temperature port and a liquid level gauge interface.

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