A thermostat device for MMA acylation production

Abstract

The present application relates to the technical field of chemical production, disclose a kind of for MMA acylation production thermostat, including multiple buffer box, after the mixture formed by mixing acetone cyanhydrin and nitrogen is slowly, dispersedly released into acylation reactor, so that acetone cyanhydrin can be gradually contacted with sulfuric acid and react, to evenly disperse the reaction itself and its released heat to the entire reactor, compared with prior art, the present application can reduce the local overheating problem caused by the concentrated addition of acetone cyanhydrin, thereby improving the stability of reaction.In addition, the circulation structure can drive the acetone cyanhydrin and sulfuric acid in the acylation reactor to form a circulating motion, promote the acetone cyanhydrin and sulfuric acid to flow and contact in the acylation reactor, thereby improving the uniformity of the acylation reaction of acetone cyanhydrin and sulfuric acid.

Description

Technical Field

[0001] This invention relates to the technical field of chemical production, and specifically to a constant temperature device for the production of MMA acylation. Background Technology

[0002] Methyl methacrylate (MMA), also known as methyl isobutylene acrylate, is an organic compound with the chemical formula C5H8O2. It is a colorless liquid, slightly soluble in water, and soluble in most organic solvents such as ethanol. It is mainly used as a monomer for plexiglass, and is also used in the manufacture of other resins, plastics, coatings, adhesives, lubricants, impregnating agents for wood and cork, paper varnishes, etc.

[0003] In China, methyl methacrylate (Mmethacrylate) is mostly produced using the acetone cyanohydrin (ACY) process. In this process, sulfuric acid and ACY are simultaneously injected into the acylation reactor. The ACY and sulfuric acid undergo an acylation reaction within the reactor, generating a large amount of heat that rapidly raises the temperature of the reactor. To maintain a stable reaction temperature, a jacket is installed around the reactor, with channels for hot water to flow through it. As the hot water flows through these channels, it carries away the heat generated by the acylation reactor, reducing its temperature and maintaining a stable reaction temperature.

[0004] However, during the injection of sulfuric acid and acetone cyanohydrin into the acylation reactor, a large amount of acetone cyanohydrin and sulfuric acid are concentrated at the junction of the acetone cyanohydrin inlet and the sulfuric acid inlet of the acylation reactor, where the acylation reaction will release a large amount of heat. The heat accumulates rapidly in this area, and the hot water in the jacket is unable to remove the large amount of heat accumulated in this area in time, which leads to unstable reaction temperature in the reactor and thus affects the stability of product quality. Summary of the Invention

[0005] The present invention aims to provide a constant temperature device for MMA acylation production, which can improve the uniformity of the acylation reaction between acetone cyanohydrin and sulfuric acid in the acylation reactor and improve the stability of the reaction temperature in the acylation reactor.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: 1) A constant temperature device for MMA acylation production, comprising an acylation reactor, an outer jacket for hot water flow, a discharge port for material discharge at the top of the side wall of the acylation reactor, a first feed pipe for injecting sulfuric acid at the bottom of the acylation reactor, several buffer boxes evenly distributed along their height direction inside the acylation reactor, a second feed pipe for injecting acetone cyanohydrin and a gas pipe for injecting nitrogen into the buffer boxes connected to the buffer boxes, several through holes on the buffer boxes, an exhaust structure for exhausting gas at the top of the acylation reactor, a stirring structure for stirring the sulfuric acid and acetone cyanohydrin inside the acylation reactor, and a circulation structure for circulating the sulfuric acid and acetone cyanohydrin inside the acylation reactor.

[0007] In this invention, sulfuric acid is continuously fed into the acylation reactor through the first feed pipe at the bottom of the acylation reactor; simultaneously, nitrogen gas is introduced into the buffer box, which can push any sulfuric acid that may enter the buffer box back into the acylation reactor; with the continuous introduction of nitrogen gas, acetone cyanohydrin is injected into the buffer box, and nitrogen gas and acetone cyanohydrin are mixed in the buffer box. Under the pressure of the gas, the mixture formed by nitrogen gas and acetone cyanohydrin enters the acylation reactor through the through hole.

[0008] Because the buffer boxes are distributed along the height of the acylation reactor, acetone cyanohydrin and nitrogen can be dispersed into the acylation reactor from multiple locations, reducing the possibility of concentrated addition of acetone cyanohydrin. After the acetone cyanohydrin in each buffer box flows out through the through holes, the acetone cyanohydrin entering the acylation reactor is further dispersed. Subsequently, the acetone cyanohydrin begins to move downward under the action of gravity. During the downward movement, it comes into contact with sulfuric acid and gradually undergoes an acylation reaction. The heat generated by the acylation reaction is also dispersed to different areas of the reactor, thereby reducing the possibility of local overheating caused by concentrated addition of acetone cyanohydrin. Secondly, the acetone cyanohydrin flowing out through the top opening of the buffer box will first flow and spread at the top of the buffer box, and then fall to the bottom of the reactor under the action of gravity. This prolongs the flow time of the acetone cyanohydrin, allowing it more time to contact sulfuric acid and undergo acylation before falling to the bottom of the acylation reactor. This reduces the risk of overheating at the bottom of the acylation reactor due to the acylation reaction being concentrated there. At the same time, nitrogen gas enters the acylation reactor, moves upward, and is discharged through the exhaust structure. As the nitrogen gas is discharged, it can carry away some heat, which helps to maintain the temperature stability of the acylation reactor.

[0009] Furthermore, the acylation reactor is equipped with a circulation structure, which drives the acetone cyanohydrin and sulfuric acid within the reactor to circulate, promoting sufficient flow and contact between the two substances and thus improving the uniformity of the acylation reaction. Simultaneously, with the circulation of acetone cyanohydrin and sulfuric acid, the heat released by the acylation reaction is carried to various areas of the reactor, rather than accumulating in the concentrated reaction zone, thereby reducing localized overheating and improving the stability of the acylation reaction.

[0010] 2) A constant temperature apparatus for MMA acylation production as described in 1), wherein: The circulation structure includes a circulation pipe, one end of which is connected to the bottom of the acylation reactor, and the other end of which is connected to the top of the acylation reactor and extends into the acylation reactor. A first suction pump is installed on the circulation pipe.

[0011] In this invention, a first suction pump draws acetone cyanohydrin and sulfuric acid from the bottom of the acylation reactor into a circulation pipe. The acetone cyanohydrin and sulfuric acid are then continuously transported along the circulation pipe and flow out through an opening inside the acylation reactor, returning to the reactor. By continuously drawing away the acetone cyanohydrin and sulfuric acid from the bottom of the acylation reactor and reinjecting them from the top, the acetone cyanohydrin and sulfuric acid can flow and contact sufficiently, allowing for a more uniform acylation reaction. Furthermore, with the circulating flow of acetone cyanohydrin and sulfuric acid, the heat released during the acylation reaction is carried to various areas of the acylation reactor, rather than accumulating in the concentrated reaction zone, thus reducing localized overheating within the reactor and improving the stability of the acylation reaction.

[0012] 3) A constant temperature apparatus for MMA acylation production as described in 2), wherein: A first control valve for controlling the flow rate is installed inside the circulation pipe.

[0013] In this invention, a first control valve is installed inside the circulation pipe to control the flow rates of acetone cyanohydrin and sulfuric acid liquids within the circulation pipe. During actual production, the opening of the first control valve can be adjusted according to specific production needs: when the opening of the first control valve increases, the flow rates of acetone cyanohydrin and sulfuric acid in the circulation pipe increase accordingly, which accelerates the circulation speed of acetone cyanohydrin and sulfuric acid, thereby promoting sufficient contact between acetone cyanohydrin and sulfuric acid and ultimately improving the acylation reaction efficiency of acetone cyanohydrin and sulfuric acid; when the opening of the first control valve decreases, the flow rates of acetone cyanohydrin and sulfuric acid in the circulation pipe decrease accordingly, and the circulation speed of acetone cyanohydrin and sulfuric acid decreases accordingly, thus slowing down the acylation reaction efficiency of acetone cyanohydrin and sulfuric acid.

[0014] 4) A constant temperature apparatus for MMA acylation production according to 1), wherein: The stirring structure includes a stirring shaft installed inside the acylation reactor. The top end of the stirring shaft passes through the top wall of the acylation reactor and is connected to a servo motor. The stirring shaft is clearance-fitted with the top wall of the acylation reactor. The servo motor is located on the outside of the top of the acylation reactor. The other end of the stirring shaft extends towards the bottom of the acylation reactor. Several stirring paddles are provided on the stirring shaft. Buffer boxes are located on both sides of the stirring shaft. There are gaps between adjacent buffer boxes to allow the stirring paddles to pass through.

[0015] In this invention, a servo motor is started, which drives the stirring shaft to rotate. As the stirring shaft rotates, the stirring paddle rotates accordingly. During the rotation of the stirring paddle, the sulfuric acid and acetone cyanohydrin in the acylation reactor can flow and be fully mixed through shearing and pushing forces, thereby making the acylation reaction more uniform. At the same time, the flow of sulfuric acid and acetone cyanohydrin also enhances the heat exchange efficiency between the heat generated by the acylation reaction and the hot water in the jacket.

[0016] 5) A constant temperature apparatus for MMA acylation production according to 1), wherein: The buffer box is equipped with several heat sinks. One end of the heat sink is connected to the side wall of the buffer box, and the end of the heat sink away from the buffer box passes through the side wall of the acylation reactor and the jacket in sequence and extends outward from the jacket.

[0017] In this invention, the heat sink can absorb and conduct heat generated inside and around the buffer box due to the acylation reaction. The end of the heat sink furthest from the buffer box passes sequentially through the sidewall of the acylation reactor and the jacket, extending outwards from the jacket. The heat sink extending to the outside of the jacket is exposed to the external environment, allowing it to dissipate the heat absorbed and conducted by the heat sink into the air. This improves the heat dissipation effect of the buffer box, reduces heat accumulation in and around the buffer box, and thus enhances the stability of the acylation reaction.

[0018] 6) A constant temperature apparatus for MMA acylation production according to 1), wherein: The jacket is equipped with several partition plates, which divide the internal space of the jacket into several chambers for the flow of hot water. All chambers are connected to a chiller for preparing hot water for supply and discharge.

[0019] In this invention, hot water is prepared using a chiller and then introduced into various chambers around the acylation reactor. As the hot water flows through the chambers, it carries away the heat from the corresponding parts of the acylation reactor. Compared to the hot water flowing throughout the entire jacket, the flow path of the hot water in each chamber is shortened, thereby reducing the likelihood of the hot water heating up due to continuous heat absorption during flow. This allows the hot water to maintain a lower temperature and a stronger heat absorption capacity, enabling it to promptly remove the heat generated by the acylation reactor and maintain the stability of the reaction temperature within the reactor.

[0020] 7) A constant temperature apparatus for MMA acylation production according to 6), wherein: The positions of the chambers correspond one-to-one with the positions of the buffer boxes.

[0021] In this invention, after acetone cyanohydrin flows out from the through-holes in the buffer box, it comes into contact with sulfuric acid in the reactor and undergoes an acylation reaction, causing the heat generated by the reaction to be concentrated and released in the buffer box and its surrounding area. Since the positions of the chambers correspond one-to-one with the positions of the buffer boxes, the hot water flowing in the chambers can be precisely applied to each buffer box and its surrounding area, thereby directly removing the heat of reaction generated by the acylation reaction in that area, thus improving the overall efficiency of maintaining the stability of the reaction temperature inside the acylation reactor.

[0022] 8) A constant temperature apparatus for MMA acylation production according to 6), wherein: The chamber is connected to a secondary outlet pipe and a secondary return pipe on both sides. The ends of all the secondary outlet pipes away from the chamber are connected to the main outlet pipe. The end of the main outlet pipe away from the secondary outlet pipes is connected to the outlet of the chiller. The ends of all the secondary return pipes away from the chamber are connected to the main return pipe. The end of the main return pipe away from the secondary return pipes is connected to the return port of the chiller. A second suction pump is installed on the main return pipe.

[0023] In this invention, the hot water prepared by the chiller flows into each secondary outlet pipe through the main outlet pipe and is injected into each chamber through the secondary outlet pipe. Under the suction action of the second suction pump, the hot water flows towards the secondary return pipe. During the flow of the hot water, it continuously absorbs the reaction heat conducted by the acylation reactor wall. The hot water after absorbing heat flows into each secondary return pipe and enters the main return pipe under the suction action of the second suction pump, and finally returns to the chiller for cooling.

[0024] Compared with the prior art, the present invention also has the following technical effects: In this invention, acetone cyanohydrin is mixed with nitrogen and then slowly and dispersedly released into the acylation reactor through multiple buffer chambers. This allows acetone cyanohydrin to gradually contact and react with sulfuric acid, thereby uniformly distributing the reaction and its released heat throughout the reactor. Compared with existing technologies, this invention reduces the problem of localized overheating caused by concentrated addition of acetone cyanohydrin, thus improving the stability of the reaction. Furthermore, the circulation structure drives the acetone cyanohydrin and sulfuric acid within the acylation reactor to circulate, promoting sufficient flow and contact between the two substances, thereby improving the uniformity of the acylation reaction. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of a constant temperature device for MMA acylation production according to the present invention.

[0026] Figure 2 for Figure 1 Sectional view at point AA. Detailed Implementation

[0027] The following detailed description illustrates the specific implementation method: The reference numerals in the accompanying drawings include: acylation reactor 1, jacket 2, outlet 3, first feed pipe 4, buffer box 5, gas pipe 6, through hole 7, circulation pipe 8, first suction pump 9, control valve 10, stirring shaft 11, servo motor 12, stirring paddle 13, heat sink 14, partition plate 15, chamber 16, chiller 17, secondary water outlet pipe 18, secondary water return pipe 19, main water outlet pipe 20, main water return pipe 21, second suction pump 22, and second feed pipe 23.

[0028] See the example. Figure 1 As shown, this embodiment of a constant temperature device for MMA acylation production includes an acylation reactor 1. The acylation reactor 1 is externally welded with a jacket 2 for hot water flow. The top of the side wall of the acylation reactor 1 has a discharge port 3 for discharging material. A first valve is connected to the discharge port 3 via a flange. The bottom of the acylation reactor 1 is connected to a first feed pipe 4 via a flange. A second valve is connected to the first feed pipe 4 via a flange. The end of the first feed pipe 4 away from the acylation reactor 1 is connected to a sulfuric acid storage tank. An exhaust port is opened at the top of the acylation reactor 1, and an exhaust valve is installed on the exhaust port via a flange.

[0029] See Figure 2 As shown, several buffer boxes 5 are welded inside the acylation reactor 1, arranged along its height. Several through holes 7 are opened on the buffer boxes 5. A second feed pipe 23 is connected to the buffer boxes 5 through a flange. A third valve is connected to the second feed pipe 23 through a flange. The end of the second feed pipe 23 away from the buffer boxes 5 passes through the side wall of the acylation reactor 1 and the jacket 2 in sequence and is connected to the acetone cyanohydrin storage tank. A gas pipe 6 is also connected to the buffer boxes 5 through a flange. A fourth valve is connected to the gas pipe 6 through a flange. A nitrogen generator is connected to the end of the gas pipe 6 away from the buffer boxes 5. Two heat sinks 14 are welded on the buffer boxes 5. The end of the heat sink 14 away from the buffer boxes 5 passes through the side wall of the acylation reactor 1 and the jacket 2 in sequence and extends to the outside of the jacket 2. The heat sinks 14 are all welded to the side wall of the acylation reactor 1 and the jacket 2.

[0030] It also includes a circulation pipe 8, one end of which is connected to the bottom of the acylation reactor 1 via a flange. A first sealing ring is installed between the circulation pipe 8 and the bottom of the acylation reactor 1. The other end of the circulation pipe 8 is connected to the top of the acylation reactor 1 via a flange and extends into the acylation reactor 1. A second sealing ring is installed between the circulation pipe 8 and the top of the acylation reactor 1. A first suction pump 9 is connected to the circulation pipe 8 via a flange. A control valve 10 is installed on the circulation pipe 8 via a flange.

[0031] A servo motor 12 is mounted on the outer side of the top of the acylation reactor 1 by bolts and nuts. The output shaft of the servo motor 12 is fixedly connected to a stirring shaft 11 by a coupling. The end of the stirring shaft 11 away from the servo motor 12 passes through the top of the acylation reactor 1 and extends into the interior of the acylation reactor 1. The stirring shaft 11 is clearance-fitted with the top of the acylation reactor 1. A third sealing ring is installed between the stirring shaft 11 and the top of the acylation reactor 1. The other end of the stirring shaft 11 is rotatably connected to the bottom of the acylation reactor 1 by a bearing. Several stirring paddles 13 are welded on the stirring shaft 11. Buffer boxes 5 are located on both sides of the stirring shaft 11. There is a gap between adjacent buffer boxes 5 for the stirring paddles 13 to pass through.

[0032] Several partition plates 15 are welded inside the jacket 2, dividing the internal space of the jacket 2 into several chambers 16 for hot water flow. The positions of the chambers 16 correspond one-to-one with the positions of the buffer box 5. The two sides of the chambers 16 are connected to secondary outlet pipes 18 and secondary return pipes 19 through flanges, respectively. A fifth valve is connected to the secondary outlet pipe 18 through a flange. The ends of all secondary outlet pipes 18 away from the chambers 16 are connected to the main outlet pipe 20 through flanges. The end of the main outlet pipe 20 away from the secondary outlet pipes 18 is connected to the outlet of the chiller 17 through a flange. The ends of all secondary return pipes 19 away from the chambers 16 are connected to the main return pipe 21 through flanges. The end of the main return pipe 21 away from the secondary return pipes 19 is connected to the return port of the chiller 17 through a flange. A second suction pump 22 is installed on the main return pipe 21 through a flange.

[0033] The specific implementation process of this embodiment is as follows: First, the second and fourth valves are opened simultaneously, and sulfuric acid continuously enters the acylation reactor 1 from the bottom through the first feed pipe 4. Nitrogen enters the buffer box 5 through the gas pipe 6, pushing any sulfuric acid that may enter the buffer box 5 out of the box through gas pressure. Then, the third valve is opened, allowing acetone cyanohydrin and nitrogen to enter the buffer box 5 simultaneously. The acetone cyanohydrin and nitrogen in the buffer box 5 are mixed and flow into the acylation reactor 1 through the through hole 7. The acetone cyanohydrin comes into contact with the sulfuric acid and gradually undergoes an acylation reaction.

[0034] Simultaneously, the fifth valve and the second suction pump 22 are opened, and the hot water prepared by the chiller 17 flows into each secondary outlet pipe 18 through the main outlet pipe 20, and then enters each chamber 16 to continue flowing. During the flow of the hot water, it continuously absorbs the reaction heat conducted by the wall of the acylation reactor 1. The hot water after absorbing heat flows into each secondary return pipe 19, and then flows into the main return pipe 21 through each secondary return pipe 19. Finally, it returns to the chiller 17 through the main return pipe 21 for cooling treatment, which facilitates subsequent heat absorption through recirculation.

[0035] When the servo motor 12 is started, the output shaft of the servo motor 12 begins to rotate, driving the stirring shaft 11 to rotate. As the stirring shaft 11 rotates, it drives the stirring paddle 13 to rotate as well, thereby stirring the acetone cyanohydrin and nitrogen in the acylation reactor 1, thus making the acylation reaction more uniform overall.

[0036] The above are merely embodiments of the present invention. Commonly known technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solution of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A constant temperature apparatus for MMA acylation production, characterized in that, The reactor includes an acylation reactor, which is fitted with a jacket for hot water flow. The top of the reactor's side wall has a discharge port for discharging material. The bottom of the reactor is connected to a first feed pipe for injecting sulfuric acid. The reactor is characterized by having several buffer boxes evenly distributed along its height. Each buffer box is connected to a second feed pipe for injecting acetone cyanohydrin and a gas pipe for injecting nitrogen. Each buffer box has several through holes. The top of the reactor has an exhaust structure for venting gas. The reactor also has a stirring structure for agitating the sulfuric acid and acetone cyanohydrin. Finally, the reactor has a circulation structure for circulating the sulfuric acid and acetone cyanohydrin.

2. The constant temperature apparatus for MMA acylation production according to claim 1, characterized in that: The circulation structure includes a circulation pipe, one end of which is connected to the bottom of the acylation reactor, and the other end of which is connected to the top of the acylation reactor and extends into the acylation reactor. A first suction pump is installed on the circulation pipe.

3. A constant temperature apparatus for MMA acylation production according to claim 2, characterized in that: The circulation pipe is equipped with a control valve for controlling the flow rate.

4. A constant temperature apparatus for MMA acylation production according to claim 1, characterized in that: The stirring structure includes a stirring shaft disposed inside the acylation reactor. The top end of the stirring shaft passes through the top wall of the acylation reactor and is connected to a servo motor. The stirring shaft is clearance-fitted with the top wall of the acylation reactor. The servo motor is disposed on the outer side of the top of the acylation reactor. The other end of the stirring shaft extends toward the bottom of the acylation reactor. Several stirring paddles are disposed on the stirring shaft. Buffer boxes are disposed on both sides of the stirring shaft, and there are gaps between adjacent buffer boxes for the stirring paddles to pass through.

5. A constant temperature apparatus for MMA acylation production according to claim 1, characterized in that: The buffer box is provided with several heat sinks. One end of the heat sink is connected to the side wall of the buffer box, and the other end of the heat sink passes through the side wall of the acylation reactor and the jacket in sequence and extends outward from the jacket.

6. A constant temperature apparatus for MMA acylation production according to claim 1, characterized in that: The jacket is equipped with several partition plates, which divide the internal space of the jacket into several chambers for the flow of hot water. All chambers are connected to a chiller for preparing hot water for the flow of hot water.

7. A constant temperature apparatus for MMA acylation production according to claim 6, characterized in that: The positions of the chambers correspond one-to-one with the positions of the buffer boxes.

8. A constant temperature apparatus for MMA acylation production according to claim 6, characterized in that: The chamber is connected to a secondary outlet pipe and a secondary return pipe on both sides. The ends of all the secondary outlet pipes away from the chamber are connected to a main outlet pipe. The end of the main outlet pipe away from the secondary outlet pipes is connected to the outlet of the chiller. The ends of all the secondary return pipes away from the chamber are connected to a main return pipe. The end of the main return pipe away from the secondary return pipes is connected to the return port of the chiller. A second suction pump is installed on the main return pipe.

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