Acrylic acid heavy component decomposition kettle

Abstract

The utility model relates to the technical field of decomposition kettles, in particular to an acrylic acid heavy component decomposition kettle which comprises a decomposition kettle body, a stirring assembly is installed inside the decomposition kettle body, and a negative pressure distillation assembly is installed outside the decomposition kettle body. The negative pressure distillation assembly comprises a distillation pipe, an exhaust pipe and a hot water pipe which are mounted at the top of the decomposition kettle body, one ends of the distillation pipe, the exhaust pipe and the hot water pipe extend into the decomposition kettle body, and the end, away from the decomposition kettle body, of the exhaust pipe is communicated with a vacuum pump; first valves are installed at the ends, close to the decomposition kettle body, of the distillation pipe, the exhaust pipe and the hot water pipe, the decomposition kettle body is sleeved with a jacket, and one side of the jacket is communicated with a steam pipe with one end extending into the jacket. The problems that the discharging speed is low and the discharging is not thorough after the crylic acid reconstitution is split, so that part of split crylic acid light components are polymerized in the kettle, and finally the viscosity of residues in the kettle is increased due to high crylic acid content are solved.

Description

Technical Field

[0001] The utility model relates to the technical field of decomposition kettles, in particular to an acrylic acid heavy component decomposition kettle. Background Art

[0002] Industrially, a gas containing acrylic acid is prepared by gas-phase oxidation of propylene or acrolein in the presence of a catalyst. The gas containing acrylic acid is absorbed by a solvent to form a liquid acrylic acid solution. The acrylic acid product is obtained by distilling the acrylic acid solution. Impurities with high boiling points are removed during the purification process. The liquid containing high boiling point impurities is called acrylic acid heavy components in the industry and is usually discharged.

[0003] Existing scheme: the temperature in the kettle rises to 170-175℃ under normal pressure, the material is discharged by keeping warm, and the discharge is completed after 24 hours. The waste residue is discharged into the waste liquid intermediate tank and then incinerated.

[0004] According to the changes in the light components produced by the recombinant cracking in the kettle, some light components aggregate. It is analyzed that this is directly related to the decomposition temperature and the discharge rate. Therefore, it is necessary to change the decomposition temperature, decomposition pressure and discharge rate. At the same time, it should be ensured that no new components appear in the semi-finished products, the residue viscosity meets the standards, and does not affect the production of subsequent sections. Utility Model Content

[0005] In view of the shortcomings of the prior art, the utility model provides an acrylic acid heavy component decomposition kettle, which solves the problems of slow discharge speed and incomplete discharge after acrylic acid recombinant decomposition, resulting in polymerization of some cracked acrylic acid light components in the kettle, and finally the residue in the kettle has increased viscosity due to high acrylic acid content.

[0006] To achieve the above object, the utility model provides the following technical solutions: an acrylic acid heavy component decomposition kettle, comprising a decomposition kettle body, a stirring assembly is installed inside the decomposition kettle body, and a negative pressure distillation assembly is installed outside the decomposition kettle body;

[0007] The negative pressure distillation assembly includes a distillation tube, an exhaust pipe and a hot water pipe installed on the top of the decomposition kettle body. One end of the distillation tube, the exhaust pipe and the hot water pipe extend into the interior of the decomposition kettle body. The end of the exhaust pipe away from the decomposition kettle body is connected to a vacuum pump. The end of the distillation tube, the exhaust pipe and the hot water pipe close to the decomposition kettle body is installed with a first valve.

[0008] Preferably, the outer sheath of the decomposition kettle body is provided with a jacket, one side of the jacket is connected to a steam pipe with one end extending into the interior thereof, and a second valve is installed at one end of the steam pipe close to the jacket.

[0009] Preferably, the steam pipe includes a horizontal tube with one end extending into the interior of the jacket, the end of the horizontal tube away from the jacket is connected to an inclined tube, the end of the inclined tube away from the horizontal tube is connected to an air inlet pipe, both ends of the inclined tube are rotatably connected to the horizontal tube and the air inlet pipe through a sleeve, and the bottom of the inclined tube is connected to a semicircular tube.

[0010] Preferably, the stirring assembly comprises a bracket rotatably connected to the inner top of the decomposition kettle body, a push plate is fixedly connected to the bottom of the bracket, and a motor for driving the bracket to rotate is fixedly connected to the top of the decomposition kettle body.

[0011] Preferably, the push plate includes a longitudinal plate in the middle of the bracket and two folding plates at both ends of the bracket, and one end of the folding plate close to the longitudinal plate is a plane.

[0012] Preferably, the bottom of the decomposition kettle body is connected to a slag discharge pipe, and a third valve is installed at one end of the slag discharge pipe close to the decomposition kettle body.

[0013] Preferably, a plurality of supporting legs are fixedly connected to the bottom of the decomposition kettle body, and pads are fixedly connected to the bottoms of the supporting legs.

[0014] Compared with the prior art, the utility model provides an acrylic acid heavy component decomposition kettle, which has the following beneficial effects:

[0015] 1. By setting up a negative pressure distillation component and using a reduced pressure distillation method, the discharge speed is increased to prevent the light component from staying too long and inducing polymerization, which leads to the polymerization of some of the cracked acrylic acid light components in the kettle. Finally, the viscosity of the residue in the kettle increases due to the high acrylic acid content. In the gas phase separation process, the hot water vaporization entrainment method is used to increase the gas phase component content, so that the gas phase is distilled and discharged to a greater extent, reducing the acrylic acid light components remaining in the reactor, making the discharge more thorough, and shortening the single kettle decomposition time.

[0016] 2. The steam pipe is set up to divert steam and condensed water, reduce the contact between condensed water and steam inside the jacket, reduce the heat loss of steam due to contact with condensed water with lower temperature, and maximize the utilization rate of steam heat.

[0017] 3. By setting the angles of the folding plates in the push plate to be more, the acrylic acid heavy component can be pushed in different directions, which promotes the acrylic acid heavy component to flow in different directions and then accelerate the mixing, thereby improving the stirring efficiency of the acrylic acid heavy component and accelerating the dissolution of the acrylic acid heavy component. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0019] Figure 1 It is a schematic diagram of the overall structure of the utility model;

[0020] Figure 2 It is an internal cutaway view of the utility model as a whole;

[0021] Figure 3 This is a schematic diagram of the structure of the bracket and the push plate of the utility model;

[0022] Figure 4 It is a structural schematic diagram of the steam pipe of the utility model.

[0023] In the figure: 1. decomposition kettle body; 2. stirring assembly; 21. bracket; 22. push plate; 23. motor; 3. negative pressure distillation assembly; 31. distillation tube; 32. exhaust pipe; 33. hot water pipe; 34. vacuum pump; 35. first valve; 4. jacket; 5. steam pipe; 51. horizontal pipe; 52. inclined pipe; 53. air inlet pipe; 54. semicircular pipe; 6. second valve; 7. slag discharge pipe; 8. third valve; 9. support leg; 10. cushion block. DETAILED DESCRIPTION

[0024] The following will describe the implementation methods of the present application in detail with the help of accompanying drawings and examples, so that the implementation process of how the present application uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0025] Example

[0026] Figure 1-Figure 4 The utility model is an embodiment of an acrylic acid heavy component decomposition kettle, comprising a decomposition kettle body 1, a stirring component 2 is installed inside the decomposition kettle body 1, a negative pressure distillation component 3 is installed outside the decomposition kettle body 1, acrylic acid heavy components and hot water are put into the decomposition kettle body 1, and the temperature inside the decomposition kettle body 1 is controlled to be 165°C. After the stirring component 2 starts to work, the acrylic acid heavy components and hot water inside the decomposition kettle body 1 are stirred, and then the negative pressure distillation component 3 starts to work, and the vacuum degree inside the decomposition kettle body 1 is controlled to be -0.095MP for reduced pressure distillation for 12 hours. After the reduced pressure distillation is completed, water is added, and the water addition flow rate is 220kg / h. In the component separation process, the reduced pressure distillation method is used to increase the discharge speed, prevent the light component from staying too long to induce polymerization, and cause the light component of acrylic acid after partial cracking to polymerize in the kettle. Finally, the viscosity of the residue in the kettle increases due to the high acrylic acid content. In the gas phase separation process, the hot water vaporization entrainment method is used to increase the gas phase component content, so that the gas phase is distilled and discharged to a greater extent, reducing the light component of acrylic acid remaining in the reactor, and the discharge is more thorough, while shortening the single kettle decomposition time.

[0027] The negative pressure distillation assembly 3 includes a distillation tube 31, an exhaust pipe 32 and a hot water pipe 33 installed on the top of the decomposition kettle body 1. One end of the distillation tube 31, the exhaust pipe 32 and the hot water pipe 33 all extend into the interior of the decomposition kettle body 1. The end of the exhaust pipe 32 away from the decomposition kettle body 1 is connected to a vacuum pump 34. The ends of the distillation tube 31, the exhaust pipe 32 and the hot water pipe 33 close to the decomposition kettle body 1 are all installed with a first valve 35. First, the acrylic acid heavy component and hot water are added into the decomposition kettle body 1 in proportion, and then the vacuum pump is turned on to draw 5000kg of acrylic acid heavy component into the 10000L reactor. The stirring assembly 2 starts to work to maintain the temperature inside the decomposition kettle body 1. Then the first valve 35 on the hot water pipe 33 is opened, and hot water is added according to the feed ratio. During the reaction, if the temperature The temperature is obviously reduced by reducing the amount of water inlet to maintain the temperature. The vacuum pump 34 evacuates the inside of the decomposition kettle body 1, and the first valve 35 on the distillation tube 31 is opened to perform reduced-pressure distillation on the light components of acrylic acid in the decomposition kettle body 1. After the normal discharge, sampling and analysis are performed 1 hour later, and the DCS keeps records. The sampling and analysis results show that the acrylic acid content is less than 10%, which can be considered to be the end of the cracking reaction. The speed and thoroughness of the discharge of the light components of acrylic acid produced by the recombinant cracking of acrylic acid are accelerated, and the amount of the light components of acrylic acid remaining in the decomposition kettle body 1 is reduced, thereby improving the recovery rate of the heavy components of acrylic acid and reducing the residue concentration after the recombinant cracking of acrylic acid. At the same time, no new hazardous chemicals are added, and the decomposed semi-finished products are conducive to the continuous and stable production of subsequent devices, and the decomposition time is shortened, which reduces energy consumption.

[0028] The outer sleeve of the decomposition kettle body 1 is provided with a jacket 4, one side of the jacket 4 is connected to a steam pipe 5 with one end extending into the interior thereof, and a second valve 6 is installed at one end of the steam pipe 5 close to the jacket 4. Before hot water is added to the interior of the decomposition kettle body 1, the second valve 6 is first opened to pass steam from the steam pipe 5 into the interior of the jacket 4. The steam inside the jacket 4 heats the interior of the decomposition kettle body 1 until the temperature inside the decomposition kettle body 1 reaches the requirement, thereby facilitating the control of the reaction temperature inside the decomposition kettle.

[0029] The steam pipe 5 includes a transverse pipe 51 with one end extending into the interior of the jacket 4, an end of the transverse pipe 51 away from the jacket 4 is connected to an inclined pipe 52, and an end of the inclined pipe 52 away from the transverse pipe 51 is connected to an air inlet pipe 53, both ends of the inclined pipe 52 are rotatably connected to the transverse pipe 51 and the air inlet pipe 53 through sleeves, and a semicircular pipe 54 is connected to the bottom of the inclined pipe 52. When the steam passes through the steam pipe 5 into the interior of the jacket 4, the staff rotates the inclined pipe 52 until the semicircular pipe 54 moves to the bottom of the inclined pipe 52. At this time, the steam passes through the air inlet pipe 53, the inclined pipe 52 and the transverse pipe 51 in sequence and enters the interior of the jacket 4. Since the steam temperature is high and there is a tendency to flow upward, the semicircular pipe 54 is in the inclined position. The amount of steam entering the semicircular tube 54 below the inclined tube 52 is small, and the heat loss generated by the steam passing through the steam pipe 5 is low. The steam temperature inside the jacket 4 gradually decreases and some condensed water is generated. The condensed water drips to the bottom of the jacket 4 and flows into the inclined tube 52 along the horizontal tube 51, and then flows into the semicircular tube 54 directly below the inclined tube 52. Since the position of the semicircular tube 54 is relatively low, the condensed water will not flow out before filling the semicircular tube 54, which plays a role in diverting steam and condensed water, reducing the contact between the condensed water and steam inside the jacket, reducing the heat loss of steam due to contact with the condensed water with lower temperature, and maximizing the utilization rate of steam heat.

[0030] When the decomposition kettle needs to drain the condensed water after work is finished, the staff rotates the semicircular tube 54 to be directly above the inclined tube 52. At this time, the height of the semicircular tube 54 exceeds the height of the inclined tube 52, and the condensed water inside the semicircular tube 54 flows into the inclined tube 52 and then is drained through the air inlet pipe 53.

[0031] The stirring assembly 2 includes a bracket 21 rotatably connected to the inner top of the decomposition kettle body 1, a push plate 22 is fixedly connected to the bottom of the bracket 21, and a motor 23 for driving the bracket 21 to rotate is fixedly connected to the top of the decomposition kettle body 1. The push plate 22 includes a longitudinal plate in the middle of the bracket 21 and two folded plates at both ends of the bracket 21. The end of the folded plate close to the longitudinal plate is a plane. When the acrylic acid heavy component is put into the decomposition kettle body 1, the motor 23 drives the push plate 22 to rotate through the bracket 21 to stir the acrylic acid heavy component inside the decomposition kettle body 1. Since the angles of the folded plates in the push plate 22 are relatively large, the acrylic acid heavy component can be pushed in different directions, which promotes the acrylic acid heavy component to flow in different directions and then accelerates mixing, thereby improving the efficiency of stirring the acrylic acid heavy component and accelerating the decomposition and discharging of the acrylic acid heavy component.

[0032] The bottom of the decomposition kettle body 1 is connected to a slag discharge pipe 7. A third valve 8 is installed at one end of the slag discharge pipe 7 close to the decomposition kettle body 1. The tail gas recovery system pipeline is equipped to collect waste gas during the slag discharge process. When the reaction of the acrylic acid heavy component inside the decomposition kettle body 1 is completed, the third valve 8 is opened, the vacuum pump 34 is replaced with a pressure pump, and then the inside of the decomposition kettle body 1 is pressurized, and the residue is discharged from the slag discharge pipe 7. During the slag discharge process, the waste gas is controlled not to overflow. After waiting for the slag discharge to be completed, the third valve 8 is closed, and then the pressure pump stops pressurizing the inside of the decomposition kettle body 1, so as to facilitate the discharge of the residue after the acrylic acid heavy component is recovered.

[0033] A plurality of supporting legs 9 are fixedly connected to the bottom of the decomposition kettle body 1, and a pad 10 is fixedly connected to the bottom of the supporting legs 9. The supporting legs 9 play the role of supporting the decomposition kettle body 1, and the pad 10 increases the contact area between the supporting legs 9 and the ground, thereby improving the stability of the support of the decomposition kettle body 1.

[0034] Working process:

[0035] (1) Feed ratio and reaction conditions

[0036] Feeding ratio: acrylic acid heavy component: 5000kg, hot water: 2500kg;

[0037] Reaction conditions: 165°C, vacuum degree -0.095MP, reduced pressure distillation for 12h, after the reduced pressure distillation is completed, water is added at a flow rate of 220kg / h.

[0038] (2) Inspection

[0039] 2.1 After the nitrogen is pressurized to 0.1Mpa, check the pressure and leakage of the decomposition kettle;

[0040] 2.2 Steam system: pass steam through the jacket of the decomposition kettle for pressure test to ensure that there are no leaks. Before feeding, check whether the steam condensate has been drained and is ready for use;

[0041] 2.3 Confirm whether the circulating water pressure on the decomposition kettle body is normal and in standby state, whether the vacuum pump is operating normally, and whether the exhaust gas recovery system pipeline settings are correct.

[0042] (3) Feeding

[0043] Start the vacuum pump to pump 5000kg of acrylic acid heavy components into the 10000L decomposition kettle, start the stirring component, start the steam heating, pay attention to controlling the steam pressure, and control the pressure below 1.5Mpa; after the temperature of the decomposition kettle rises to the target temperature, open the first valve on the hot water pipe, and add hot water according to the feed ratio. The tail gas recovery system collects the tail gas. If the temperature drops significantly during the reaction, maintain the temperature by reducing the water intake. Take samples for analysis 1 hour after normal discharge, and keep records in DCS; the sampling and analysis results show that the acrylic acid content is <10%, which means the cracking reaction is considered to be over.

[0044] (4) Slag discharge

[0045] Open the third valve at the bottom of the decomposition kettle to discharge slag and pressurize the reactor. During the decomposition process, control the waste gas to prevent it from overflowing. After the decomposition is completed, close the third valve at the bottom of the decomposition kettle. After the decomposition is completed, stop pressurizing the decomposition kettle body.

[0046] (5) Sampling

[0047] Take samples for analysis, test the sugar content every hour, and send to the laboratory for analysis every two hours.

[0048] In the production process, in order to control the viscosity of the residue and ensure that the residue has good fluidity, the viscosity is controlled at 1000cps-2000cps. If the viscosity is too high, 0.2-0.4 times the material can be diluted with water and stirred to dissolve evenly.

[0049] The electrical components mentioned in this article are all connected to an external main controller and 220V mains electricity, and the main controller can be a conventional known device for controlling a computer or the like.

[0050] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0051] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An acrylic acid heavy component decomposition kettle, comprising a decomposition kettle body (1), characterized in that: A stirring assembly (2) is installed inside the decomposition kettle body (1), and a negative pressure distillation assembly (3) is installed outside the decomposition kettle body (1); The negative pressure distillation assembly (3) comprises a distillation tube (31), an exhaust tube (32) and a hot water tube (33) installed on the top of the decomposition kettle body (1); one end of the distillation tube (31), the exhaust tube (32) and the hot water tube (33) all extend into the interior of the decomposition kettle body (1); the end of the exhaust tube (32) away from the decomposition kettle body (1) is connected to a vacuum pump (34); and the ends of the distillation tube (31), the exhaust tube (32) and the hot water tube (33) close to the decomposition kettle body (1) are all installed with a first valve (35).

2. The acrylic acid heavy component decomposition kettle according to claim 1, characterized in that: The decomposition kettle body (1) is provided with a jacket (4) on the outside, one side of the jacket (4) is connected to a steam pipe (5) with one end extending into the inside thereof, and a second valve (6) is installed at one end of the steam pipe (5) close to the jacket (4).

3. The acrylic acid heavy component decomposition kettle according to claim 2, characterized in that: The steam pipe (5) comprises a transverse pipe (51) having one end extending into the interior of the jacket (4); the end of the transverse pipe (51) away from the jacket (4) is connected to an inclined pipe (52); the end of the inclined pipe (52) away from the transverse pipe (51) is connected to an air intake pipe (53); both ends of the inclined pipe (52) are rotatably connected to the transverse pipe (51) and the air intake pipe (53) via sleeves; the bottom of the inclined pipe (52) is connected to a semicircular pipe (54).

4. The acrylic acid heavy component decomposition kettle according to claim 1, characterized in that: The stirring assembly (2) comprises a bracket (21) rotatably connected to the inner top of the decomposition kettle body (1), a push plate (22) is fixedly connected to the bottom of the bracket (21), and a motor (23) for driving the bracket (21) to rotate is fixedly connected to the top of the decomposition kettle body (1).

5. The acrylic acid heavy component decomposition kettle according to claim 4, characterized in that: The push plate (22) comprises a longitudinal plate in the middle of the bracket (21) and two folding plates at both ends of the bracket (21), wherein one end of the folding plate close to the longitudinal plate is a plane.

6. The acrylic acid heavy component decomposition kettle according to claim 1, characterized in that: The bottom of the decomposition kettle body (1) is connected to a slag discharge pipe (7), and a third valve (8) is installed at one end of the slag discharge pipe (7) close to the decomposition kettle body (1).

7. The acrylic acid heavy component decomposition kettle according to claim 1, characterized in that: A plurality of supporting legs (9) are fixedly connected to the bottom of the decomposition kettle body (1), and a cushion block (10) is fixedly connected to the bottom of the supporting legs (9).

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