Process and system for producing epsilon-caprolactone

Abstract

The invention belongs to the technical field of chemical production, and particularly relates to a process and a system for producing epsilon-caprolactone, 70% hydrogen peroxide is used as an oxidizing agent to oxidize succinic anhydride, reaction can be carried out at normal temperature, reaction conditions are mild, the conversion rate is high, water brought in by reactants is consumed, generated peroxy acid is peroxysuccinic acid, and the epsilon-caprolactone can be produced by using the process and the system. Compared with peracetic acid and peracetic acid used in a traditional process, the stability and safety of peracetic acid and peracetic acid are enhanced, meanwhile, peracetic acid is a solid in a reaction solution and is easy to separate out, dehydration can be well achieved, and in the reaction of cyclohexanone and percarboxylic acid, the yield is high. According to the method, water is introduced into the solution, so that the generation of epsilon-glycolic acid, epsilon-acyloxyhexanoic acid, adipic acid, polycaprolactone and other substances caused by hydrolysis, auto-polymerization or oligomerization of epsilon-caprolactone due to introduction of water is avoided, the yield of epsilon-caprolactone is reduced, meanwhile, the reaction product succinic acid is also a solid in the solution, separation can be realized through filtration, high energy consumption in the rectification separation process is avoided, and the method is suitable for industrial production. The separation and purification difficulty of epsilon-lactone is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical production, and specifically relates to a process and system for producing ε-caprolactone. Background Art

[0002] ε-caprolactone is a widely used chemical intermediate. Its ring-opening polymerization yields polycaprolactone (PCL), which is non-toxic, harmless, and 100% biodegradable, and is an important synthetic polymer material.

[0003] Since the 1970s, many domestic enterprises have been engaged in the research and production of ε-caprolactone products. However, the domestic research on ε-caprolactone technology is still in its infancy, and there is no large-scale production. The market demand mainly relies on foreign imports to meet. With the annual increase in the domestic ε-caprolactone monomer market size, and the instability of foreign imported sources restricting the development and utilization of downstream products, the research and industrial promotion of ε-caprolactone production technology have important economic and social benefits.

[0004] There are many synthesis methods for ε-caprolactone. According to different upstream raw materials, they are mainly divided into the cyclohexanone route and the non-cyclohexanone route. Among them, the cyclohexanone route is the most widely used in industry at present, mainly including methods using cyclohexanone as the upstream raw material such as cyclohexanone peroxyacid oxidation method, cyclohexanone hydrogen peroxide oxidation method, cyclohexanone oxygen / air oxidation method, biological oxidation / bionic catalysis method, etc. Among them, peroxyacid as an oxidant has better oxidation effect, but the peroxy bond is long and weak, with poor stability, and is easily decomposed by heat and metal impurities, and is not suitable for long-term storage; there are large safety hazards in the preparation, transportation and use of peroxyacid, which greatly limits its application in industrial production. It is necessary to further improve the peroxyacid preparation process through means such as reaction intensification and process intensification. Developing an efficient and safe preparation technology for anhydrous peroxyacid is the research focus in this field.

[0005] The synthesis of ε-caprolactone is generally achieved by the Baeyer-Villiger reaction of cyclohexanone and peroxyacid under certain conditions. In the process of preparing ε-caprolactone by the indirect method using hydrogen peroxide, first, peroxyacid is prepared. Since hydrogen peroxide contains a large amount of water and water is also generated during the preparation process, the peroxycarboxylic acid solution contains a large amount of water. To reduce the impact on the oxidation reaction of cyclohexanone, it is required that the prepared peroxyacid solution is water-free. Generally, an organic solvent is added to remove the water in the peroxycarboxylic acid solution by azeotropic distillation. However, due to the azeotropic distillation process, the evaporated azeotropic solvent has a certain solubility with water, and the saturated water weight content generally reaches 2-3%. In this way, when preparing the anhydrous peroxyacid solution, the reflux ratio of distillation separation is very high, and the product energy consumption is very high. To produce one ton of ε-caprolactone product, more than 10 tons of steam are consumed in the process of preparing anhydrous peroxyacid, and a large amount of circulating cooling water is also consumed. Not only that, but also to remove the water in the peroxycarboxylic acid solution by azeotropic distillation, the required distillation time is very long. Generally, the distillation time for one batch reaction is 12 hours, which seriously reduces the production capacity of the device. At the same time, during the reaction of cyclohexanone and peroxyacid, ε-caprolactone will generate substances such as hydroxycaproic acid, adipic acid, and polycaprolactone oligomers due to hydrolysis and self-polymerization, thereby increasing the separation difficulty of caprolactone and reducing the yield of caprolactone.

[0006] In view of this, the present invention proposes a process and system for producing ε-caprolactone to solve the above technical problems. Summary of the Invention

[0007] To make up for the deficiencies of the prior art and solve the above technical problems, the present invention proposes a process and system for producing ε-caprolactone.

[0008] The technical solution adopted by the present invention to solve its technical problems is as follows: A process for producing ε-caprolactone according to the present invention includes the following steps:

[0009] A1. Peroxidation reaction: Succinic anhydride is put into dichloromethane solution, and hydrogen peroxide with a concentration of 70% is slowly added dropwise. After continuous stirring and reaction, a suspension containing solid peroxybutyric acid is obtained;

[0010] A2. Triad process: The suspension prepared in A1 is transferred into a triad unit, pressurized and filtered under the protection of inert gas in a pressurized filtration chamber, and then vacuum filtered in a vacuum filtration chamber to obtain dry peroxybutyric acid solid;

[0011] A3. Oxidation reaction: The dried peroxybutyric acid solid is slowly added to cyclohexanone and acetic acid solvent, stirred and reacted to obtain an ε-caprolactone solution with a mass concentration of 7%-20%;

[0012] A4. Filtration process: Cool the ε-caprolactone solution prepared in A3 to room temperature, filter out the generated succinic acid solid, and obtain a clear solution as the ε-caprolactone solution;

[0013] A5. Acetic acid concentration process: Rectify and concentrate the ε-caprolactone solution prepared in A4 under reduced pressure until the proportion of acetic acid solvent in the ε-caprolactone solution reaches 40%-50%;

[0014] A6. Anti-solvent crystallization process: Further filter the concentrated solution in A5 to remove the succinic acid solid, and obtain a clear ε-caprolactone solution with heavy components removed;

[0015] A7. Separation process: Conduct rectification separation operations on the ε-caprolactone solution prepared in A6 to obtain high-purity ε-caprolactone;

[0016] Among them, the three-in-one unit described in A2 includes a kettle body, a protective gas tank, and a vacuum pump;

[0017] A pressurized filtration chamber and a vacuum filtration chamber are provided in the kettle body;

[0018] The protective gas tank and the vacuum pump are both installed on the kettle body. The protective gas tank stores an inert protective gas, and the protective gas tank is used to pump the inert protective gas into the pressurized filtration chamber. The input end of the vacuum pump is connected in communication with the vacuum filtration chamber;

[0019] A dispersion and transportation mechanism is installed in the pressurized filtration chamber and the vacuum filtration chamber, and the dispersion and transportation mechanism is used to disperse, transport, and filter the suspension.

[0020] Furthermore, before the solution in A6 undergoes the filtration operation, cyclohexane needs to be added to the solution, and the molar ratio of cyclohexane to acetic acid is 1:3 - 1:5.

[0021] Furthermore, it also includes A8. Re-separation process: Re-rectify and separate the light components drawn from the top of the rectification column in A7, control the rectification temperature at 50 - 80 °C and the pressure at 1 - 20 kPa. After rectification, low-boiling cyclohexane is drawn from the top of the column, and high-boiling acetic acid is drawn from the bottom of the column and returned for reuse.

[0022] Furthermore, the dispersion and transportation mechanism includes a conveying roller, a conveying filter belt, a skirt, and a baffle;

[0023] The conveying roller is rotatably installed on the kettle body, and the conveying filter belt is jointly sleeved on the conveying roller. The conveying filter belt is made of a high-precision filter cloth material;

[0024] Skirts are fixedly installed on both sides of the conveying filter belt, and baffles are fixedly installed at uniform intervals along the length direction of the conveying filter belt. The skirts, baffles and the conveying filter belt cooperate to form a plurality of dispersion grooves.

[0025] A circulation groove is formed in the kettle body. The conveying filter belt and the skirts extend into the circulation groove. The conveying filter belt cooperates with the skirts to separate the upper and lower sides of the pressurized filtration chamber and the vacuum filtration chamber.

[0026] Furthermore, a driving motor is fixedly installed on the kettle body. A reciprocating lead screw is fixedly installed at the output end of the driving motor. A slider is installed on the reciprocating lead screw, and the slider is in screw drive with the reciprocating lead screw.

[0027] A driving wheel is installed on the kettle body. The driving wheel is fixedly connected to the conveying roller. A transmission plate is fixedly installed on the slider. Uniformly distributed deflection grooves are formed in the transmission plate. Ratchet teeth are hinged and installed in the deflection grooves through torsion springs. The transmission plate is in one-way drive with the driving wheel through the ratchet teeth.

[0028] Furthermore, at least two groups of metering pipes are fixedly installed on the kettle body. The two groups of metering pipes are both connected to the pressurized filtration chamber through one-way valve pipes. The two groups of metering pipes are respectively externally connected to a protective gas tank and a peroxidation reaction tank through one-way pipes. Sealing pistons are installed in the metering pipes. Push plates are fixedly installed on the sealing pistons. The push plates all extend to the movement path of the slider, and the push plates are elastically connected to the slider through elastic ropes.

[0029] Furthermore, a sealing groove is formed in the kettle body. The sealing groove is located between the pressurized filtration chamber and the vacuum filtration chamber. A lifting groove is formed in the sealing groove. A sealing plate is slidably installed in the lifting groove. The sealing plate cooperates with the conveyor belt, skirts and baffles to block the sealing groove.

[0030] Furthermore, the top end of the sealing plate is in sliding seal connection with the lifting groove. A telescopic cylinder is installed on the kettle body. A transmission rod is installed at the telescopic end of the telescopic cylinder. The transmission rod is designed in an F shape. The transmission rod extends to both ends of the reciprocating lead screw and is located on the movement path of the slider. The telescopic cylinder is connected to the lifting groove through a pipeline.

[0031] Furthermore, the conveying filter belt is located in the middle of the pressurized filtration chamber and the vacuum filtration chamber. The metering pipes and the vacuum pump are respectively connected to the tops of the pressurized filtration chamber and the vacuum filtration chamber. A backwashing groove is formed in the kettle body. The two ends of the backwashing groove are respectively connected to the bottoms of the pressurized filtration chamber and the vacuum filtration chamber. The output end of the vacuum pump is connected to the protective gas tank through a return pipe. A gas-liquid separator is installed in the middle of the return pipe.

[0032] A system for producing ε-caprolactone, comprising a peroxidation unit, a three-in-one unit, an oxidation unit, a filtration unit, an acetic acid concentration unit, a fractional crystallization unit, a light component separation unit and a solvent separation unit, wherein the peroxidation unit, the three-in-one unit, the oxidation unit, the filtration unit, the acetic acid concentration unit, the fractional crystallization unit, the light component separation unit and the solvent separation unit are connected in series in sequence.

[0033] The beneficial effects of the present invention are as follows:

[0034] 1. In the process and system for producing ε-caprolactone of the present invention, succinic anhydride is oxidized with 70% hydrogen peroxide as the oxidant, and the reaction can occur at room temperature. The reaction conditions are mild, the conversion rate is high, and at the same time, the water introduced in the reactants is consumed, and peroxyacid formed is peroxysuccinic acid. Compared with peracetic acid and peroxypropionic acid used in the traditional process, its stability is enhanced and the safety is improved. At the same time, peroxysuccinic acid is a solid in the reaction solution, which is easy to precipitate and can achieve dehydration well. In the reaction of cyclohexanone and percarboxylic acid, the introduction of water is avoided from causing hydrolysis, self-polymerization or oligomerization of ε-caprolactone to generate substances such as ε-hydroxycaproic acid, ε-acylcaproic acid, adipic acid and polycaprolactone, thereby reducing the yield of ε-caprolactone. At the same time, the reaction product succinic acid is also a solid in the solution and can be separated by filtration, avoiding high energy consumption in the distillation separation process and reducing the difficulty of separating and purifying ε-lactone.

[0035] 2. In the process and system for producing ε-caprolactone of the present invention, during the filtration and drying process of peroxysuccinic acid, first, inert gas is used for pressurized filtration. When the water content is relatively high, rapid separation between the solid and the liquid is caused, and most of the liquid in the suspension is rapidly separated. Then, when the water content decreases, in cooperation with the dispersion conveying mechanism, the dispersion of peroxysuccinic acid on the plane is realized. Furthermore, during the transportation process, slow dehydration and drying of peroxysuccinic acid are achieved, and during the drying process, the probability of peroxysuccinic acid being impacted and collided is reduced, thereby reducing the decomposition of peroxysuccinic acid and increasing its yield.

[0036] 3. In the process and system for producing ε-caprolactone of the present invention, by setting a metering tube and cooperating with structures such as a dispersion conveying mechanism, a reciprocating lead screw and a slider, during the drying process of peroxysuccinic acid, not only can single quantitative pumping of the suspension and inert gas be realized, but also the stages of gas-liquid pumping, gas-liquid replenishment and solid-liquid separation are carried out in an orderly manner, so that the filtration and drying operations of peroxysuccinic acid are continuous and orderly. Description of the Drawings

[0037] The present invention will be further described below with reference to the drawings.

[0038] Figure 1 is the process flow chart of the present invention;

[0039] Figure 2It is the system flow chart of the present invention;

[0040] Figure 3 It is the three-dimensional view of the three-in-one unit;

[0041] Figure 4 It is the three-dimensional view of the decentralized conveying mechanism;

[0042] Figure 5 It is the sectional view of the kettle body;

[0043] Figure 6 It is Figure 5 The partial enlarged view at position A in

[0044] Figure 7 It is the connection schematic diagram of the metering tube, one-way valve tube and one-way tube;

[0045] Figure 8 It is the three-dimensional view of the drive plate;

[0046] Figure 9 It is the sectional view of the drive plate;

[0047] Figure 10 It is the assembled three-dimensional view of the telescopic cylinder and the drive rod;

[0048] In the figure: 1, metering bin; 2, peroxidation reaction tank; 3, first condenser; 4, oil-water separator; 5, kettle body; 6, vacuum pump; 7, storage bin; 8, oxidation reaction tank; 9, first filter; 10, first intermediate tank; 11, first transfer pump; 12, first heat exchanger; 13, first distillation column; 14, second condenser; 15, first receiving tank; 16, first reboiler; 17, second transfer pump; 18, precipitation crystallization tank; 19, second filter; 20, second intermediate tank; 21, third transfer pump; 22, second heat exchanger; 23, second distillation column; 24, third condenser; 25, second receiving tank; 26, second reboiler; 27, fourth transfer pump; 28, third heat exchanger; 29, third distillation column; 30, fourth condenser; 31, third receiving tank; 32, third reboiler; 33, fifth transfer pump; 34, protective gas tank; 35, pressurized filtration chamber; 36, vacuum filtration chamber; 37, conveying roller; 38, conveying filter belt; 39, skirt; 40, baffle; 41, dispersion tank; 42, circulation tank; 43, drive motor; 44, reciprocating lead screw; 45, slider; 46, drive wheel; 47, drive plate; 48, deflection groove; 49, ratchet teeth; 50, metering tube; 51, one-way valve tube; 52, one-way tube; 53, sealing piston; 54, push plate; 55, elastic rope; 56, sealing groove; 57, lifting groove; 58, sealing plate; 59, telescopic cylinder; 60, drive rod; 61, backwash groove; 62, return pipe; 63, gas-liquid separator. Specific embodiments

[0049] In order to make the technical means, creative features, achieved purposes and effects of the present invention easily understood, the present invention will be further described below in conjunction with specific embodiments.

[0050] As Figure 1 shown, a process for producing ε-caprolactone according to the present invention is characterized by comprising the following steps:

[0051] A1. Peroxidation reaction: Succinic anhydride is put into dichloromethane solution, and hydrogen peroxide with a concentration of 70% is slowly added dropwise. At a temperature of 30 - 40 °C, continuous stirring and reaction for 1 - 2 h result in a suspension containing solid peroxysuccinic acid;

[0052] Among them, the mass ratio of m(succinic anhydride) : m(70% H2O2) is 1:1 to 2:1;

[0053] The reaction formula for preparing peroxysuccinic acid is as follows:

[0054]

[0055] A2. Transfer the suspension prepared in A1 into a three-in-one unit, and perform pressurized filtration under the protection of inert gas in the pressurized filtration chamber 35, and then perform vacuum filtration in the vacuum filtration chamber 36 to obtain dry peroxysuccinic acid solid;

[0056] Among them, a temperature control device is installed on the three-in-one unit, and the temperature inside the three-in-one unit is maintained at 30 - 50 °C, and the pressure in the vacuum filtration chamber 36 is controlled at 1 - 20 kPa;

[0057] A3. Oxidation reaction: Slowly add the dried peroxysuccinic acid solid to cyclohexanone and acetic acid solvent, stir, and react at a temperature of 20 - 60 °C for 1 - 4 h to obtain an ε-caprolactone solution with a mass concentration of 7% - 20%;

[0058] Among them, the molar ratio of peroxysuccinic acid to cyclohexanone is 1:1 - 2:1;

[0059] The reaction formula for preparing ε-caprolactone is as follows:

[0060]

[0061] A4. Filtration process: Cool the prepared ε-caprolactone solution to room temperature, and filter out the white powdery succinic acid solid generated therein to obtain a clear solution as the ε-caprolactone solution;

[0062] A5. Acetic acid concentration process: Concentrate the ε-caprolactone solution prepared in A4 (the content of acetic acid solvent is about 70%) by rectification under reduced pressure, control the pressure at 1 - 20 kPa and the temperature at 70 - 80 °C until the proportion of acetic acid solvent in the ε-caprolactone solution reaches 40% - 50%;

[0063] A6, Crystallization by antisolvent: Cyclohexane is added to the concentrated solution in A5, and after stirring and precipitation, filtration is further carried out to remove succinic acid solid, obtaining a clarified ε-caprolactone solution with heavy components removed.

[0064] The molar ratio of cyclohexane to acetic acid is 1:3 - 1:5.

[0065] A7, Separation process: The ε-caprolactone solution prepared in A6 is subjected to rectification separation operation, controlling the rectification temperature below 150 °C and the pressure at 1 - 20 kPa for rectification separation to obtain high-purity ε-caprolactone.

[0066] A8, Re-separation process: The light components taken from the top of the rectification column in A7 are subjected to rectification separation operation again, controlling the rectification temperature at 50 - 80 °C and the pressure at 1 - 20 kPa. After rectification, low-boiling cyclohexane is taken from the top of the column and high-boiling acetic acid is taken from the bottom of the column, and they are returned to the front-end process for repeated use.

[0067] In the present invention, 70% hydrogen peroxide is used as an oxidant to oxidize succinic anhydride, and the reaction can occur at room temperature. The reaction conditions are mild, the conversion rate is high, and at the same time, the water brought in by the reactants is consumed, generating peroxy acid as peroxybutyric acid, which has enhanced stability and improved safety compared with peracetic acid and peroxypropionic acid used in traditional processes.

[0068] At the same time, peroxybutyric acid is a solid in the reaction solution, which is easy to precipitate and can achieve good dehydration. In the reaction of cyclohexanone and percarboxylic acid, the introduction of water is avoided, which may cause hydrolysis, self-polymerization or oligomerization of ε-caprolactone to generate substances such as ε-hydroxycaproic acid, ε-acylcaproic acid, adipic acid and polycaprolactone, thereby reducing the yield of ε-caprolactone. At the same time, the reaction product succinic acid is also a solid in the solution, and separation can be achieved by filtration, avoiding high energy consumption in the rectification separation process and reducing the difficulty of separation and purification of ε-lactone.

[0069] As a preferred embodiment of the present invention, as Figure 3 - 10 shown, the three-in-one unit in A2 includes a kettle body 5, a protective gas tank 34 and a vacuum pump 6.

[0070] A pressure-increasing filtration chamber 35 and a vacuum filtration chamber 36 are provided in the kettle body 5. When the suspension containing solid peroxybutyric acid enters the kettle body 5, it first enters the pressure-increasing filtration chamber 35, and after pressure-increasing filtration in the pressure-increasing filtration chamber 35, it then enters the vacuum filtration chamber 36 under the transportation of the dispersion and transportation mechanism.

[0071] The protective gas tank 34 and the vacuum pump 6 are both installed on the kettle body 5. The protective gas tank 34 stores inert protective gas, and the protective gas tank 34 is used to pump the inert protective gas into the pressurized filtration chamber 35. The input end of the vacuum pump 6 is conductively connected to the vacuum filtration chamber 36. The vacuum pump 6 is used to extract the air in the vacuum filtration chamber 36. At the same time, in cooperation with the temperature control device installed on the kettle body 5, the liquid remaining on the solid peroxybutanedioic acid after pressurized filtration on the dispersion and transportation mechanism evaporates and volatilizes, further removing the moisture remaining on the solid peroxybutanedioic acid;

[0072] A dispersion and transportation mechanism is installed in the pressurized filtration chamber 35 and the vacuum filtration chamber 36. The dispersion and transportation mechanism is used to disperse, transport, and filter the suspension.

[0073] When filtering and drying the suspension containing solid peroxybutanedioic acid to reduce the water content of peroxybutanedioic acid, due to the instability of peroxybutanedioic acid itself, when the water content of peroxybutanedioic acid is lower than 12%, it is very easy to be affected by collision and impact, which will cause its decomposition. The decomposition of peroxybutanedioic acid will not only increase the oxygen content in the environment and pose an explosion risk, but also, if the degree of decomposition is too high, it will lead to a decrease in the content of peroxybutanedioic acid participating in the final reaction, and then fail to meet the requirements of subsequent oxidation reactions, resulting in a reduction in production efficiency. Therefore, when filtering and drying peroxybutanedioic acid, special attention needs to be paid to the decomposition caused by the collision between particles during the process of reducing the water content of peroxybutanedioic acid solids.

[0074] During the actual operation process, the suspension containing solid peroxybutanedioic acid is introduced into the three-in-one unit. Under the action of gravity, the suspension first flows into the pressurized filtration chamber 35, is supported by the dispersion and transportation mechanism, and flows on the dispersion and transportation mechanism to form a liquid surface with a uniform thickness. At this time, under the control of a preset control program and a controller, the protective gas tank 34 pumps inert gas into the pressurized filtration chamber 35. In this embodiment, nitrogen, argon, etc. are preferably selected as the inert gas. Under the protection and pressurization of the inert gas, the suspension on the dispersion and transportation mechanism is gradually pressure-filtered, causing the solid-liquid separation. Under the pressure-filtering action, most of the liquid is quickly discharged. At this time, the water content of the solid peroxybutanedioic acid drops rapidly. At this time, the dispersion and transportation mechanism transports the solid peroxybutanedioic acid, causing the peroxybutanedioic acid to enter the vacuum filtration chamber 36. The vacuum pump 6 continuously extracts the air in the vacuum filtration chamber 36, causing a negative pressure state in the vacuum filtration chamber 36. Under the influence of the negative pressure, the evaporation temperature of water decreases, and then the water remaining on the peroxybutanedioic acid slowly evaporates, thereby realizing the drying of the peroxybutanedioic acid. At the same time, since the peroxybutanedioic acid is in a dispersed state on the dispersion and transportation mechanism at this time, the distance between the peroxybutanedioic acid particles increases and the thickness decreases. Compared with the state of mutual stacking, not only the efficiency of filtering the residual water on the peroxybutanedioic acid is improved, but also the collision between the peroxybutanedioic acid particles can be effectively reduced, thereby reducing the decomposition rate during the drying process of the peroxybutanedioic acid and increasing the yield of the peroxybutanedioic acid.

[0075] In the filtration and drying process of peroxybutanedioic acid in the present invention, first, inert gas pressurization filtration is carried out. When the water content is relatively high, the solid-liquid separation is quickly caused, and most of the liquid in the suspension is quickly separated. Then, when the water content decreases, in cooperation with the dispersion and transportation mechanism, the peroxybutanedioic acid is dispersed on the plane, and then during the transportation process, the slow dehydration and drying of the peroxybutanedioic acid are realized. Moreover, during the drying process, the probability of the peroxybutanedioic acid being impacted and collided is reduced, thereby reducing the decomposition of the peroxybutanedioic acid and increasing its yield.

[0076] As a preferred embodiment of the present invention, the dispersion and transportation mechanism includes a conveying roller 37, a conveying filter belt 38, a skirt 39 and a baffle 40;

[0077] The conveying roller 37 is rotatably installed on the kettle body 5. The conveying filter belt 38 is jointly sleeved on the conveying roller 37. The conveying filter belt 38 is made of a high-precision filter cloth material. The number of the conveying rollers 37 is at least two. The conveying filter belt 38 is sleeved on the conveying roller 37. When the suspension is fed, the feeding position is above the conveying filter belt 38. The conveying filter belt 38 is made of a high-precision filter cloth and is woven with an ultra-fine fiber material with low water absorption and not easy to deform on the premise of meeting the conveying tension. After filtration, the solid peroxybutanedioic acid stays on the surface of the conveying filter belt 38;

[0078] Skirts 39 are fixedly installed on both sides of the conveying filter belt 38. Baffles 40 are fixedly installed at uniform intervals along the length direction of the conveying filter belt 38. The skirts 39 and the baffles 40 cooperate with the conveying filter belt 38 to form a plurality of dispersion grooves 41. The presence of the skirts 39 and the baffles 40, in conjunction with the conveying filter belt 38, forms a plurality of non-communicating dispersion grooves 41. When the suspension enters the interior of the kettle body 5, under the action of gravity, the suspension drips into the dispersion grooves 41 and flows therein. By controlling the flow rate of the suspension and the movement rate of the conveying filter belt 38, the liquid layer depth in the dispersion grooves 41 can be artificially adjusted. Due to the fluidity of the liquid, the peroxysuccinic acid entrained in the liquid will be driven to move synchronously. With the increase in its flow area, the peroxysuccinic acid is dispersed in the dispersion grooves 41. It should be noted that since the peroxysuccinic acid is wrapped by the liquid at this time, the presence of the liquid significantly reduces the impact force between the particles. At the same time, due to the relatively high water content at this time, the sensitivity of the peroxysuccinic acid to impact is relatively low. Therefore, in the pressurized filtration stage, by appropriately increasing the movement effect of the liquid in the dispersion grooves 41, the peroxysuccinic acid can be quickly dispersed.

[0079] A circulation groove 42 is provided inside the kettle body 5. The conveying filter belt 38 and the skirts 39 extend into the circulation groove 42. The conveying filter belt 38, in cooperation with the skirts 39, separates the upper and lower sides of the pressurized filtration chamber 35 and the vacuum filtration chamber 36. The presence of the circulation groove 42 is to cooperate with the conveying filter belt 38 and the skirts 39 to achieve the upper and lower isolation of the pressurized filtration chamber 35 and the vacuum filtration chamber 36. On the one hand, when receiving the suspension, it can prevent the suspension from detaching from the conveying filter belt 38. On the other hand, since the liquid exists after the suspension is dispersed in the dispersion grooves 41, the pores of the conveying filter belt 38 will be blocked. At this time, when an inert gas is pumped into the pressurized filtration chamber 35, the air pressure can act on the liquid in the dispersion grooves 41, and then, with the increase in pressure, the rate of the liquid flowing downward through the pores of the conveying filter belt 38 can be accelerated. It should be noted that in the present invention, the bottom of the pressurized filtration chamber 35 is used to collect and discharge the filtered liquid. Therefore, the bottom of the pressurized filtration chamber 35 is externally connected to a container through a pipeline, while the bottom of the vacuum filtration chamber 36 is used to collect the dried peroxysuccinic acid particles. When the conveying filter belt 38 is guided by the conveying rollers 37 to switch the movement direction, under the action of gravity, the dried peroxysuccinic acid particles fall downward. It should be noted that in order to reduce the impact generated when the peroxysuccinic acid particles fall, a storage bin 7 for storing acetic acid is placed at the bottom of the vacuum filtration chamber 36. The acetic acid is used to preserve the dried peroxysuccinic acid. After collecting a certain weight, it is directly transferred to the next process. It should be noted that the acetic acid used here is anhydrous high-purity acetic acid. The presence of acetic acid can isolate the peroxysuccinic acid from the external water-containing environment and reduce the probability of the peroxysuccinic acid being affected by oxygen and moisture in the air during subsequent position changes.

[0080] A driving motor 43 is fixedly installed on the kettle body 5. The output end of the driving motor 43 is fixedly installed with a reciprocating lead screw 44. A slider 45 is installed on the reciprocating lead screw 44. The slider 45 is in screw drive with the reciprocating lead screw 44. During the filtration and drying operation process, the driving motor 43 is in a continuously starting state, causing the reciprocating lead screw 44 to rotate continuously. The slider 45 installed on the reciprocating lead screw 44 makes a linear reciprocating slide on the surface of the kettle body 5 under the action of screw drive.

[0081] A driving wheel 46 is installed on the kettle body 5. The driving wheel 46 is fixedly connected with the conveying roller 37. A transmission plate 47 is fixedly installed on the slider 45. Uniformly distributed deflection grooves 48 are formed on the transmission plate 47. Ratchet teeth 49 are hingedly installed in the deflection grooves 48 through torsion springs. The transmission plate 47 is in one-way drive with the driving wheel 46 through the ratchet teeth 49. The sliding of the slider 45 will drive the transmission plate 47 to perform a linear reciprocating motion. Under the action of the one-way meshing drive between the ratchet teeth 49 and the driving wheel 46, within one reciprocating cycle of the slider 45, the conveying roller 37 switches between the rotating and stationary states. When the conveying roller 37 rotates, at this time the conveying filter belt 38 moves, switching the position of the dispersion tank 41 in the pressurized filtration chamber 35 and the vacuum filtration chamber 36. When the conveying roller 37 is stationary, it is convenient for the dispersion tank 41 to receive the suspension and perform pressurized filtration.

[0082] As a preferred embodiment of the present invention, at least two quantitative tubes 50 are fixedly installed on the kettle body 5. The two quantitative tubes 50 are both connected to the pressurized filtration chamber 35 through one-way valve tubes 51. The two quantitative tubes 50 are respectively externally connected to a protective gas tank 34 and a peroxidation reaction tank 82 through one-way tubes 52. Sealing pistons 53 are installed in the quantitative tubes 50. Push plates 54 are fixedly installed on the sealing pistons 53. The push plates 54 all extend to the movement path of the slider 45, and the push plates 54 are elastically connected to the slider 45 through elastic ropes 55. In the present invention, for the push plates 54 corresponding to the two quantitative tubes 50, during the movement of the slider 45, they can either contact the slider 45 simultaneously or, by adjusting the position of the push plates 54, cause the push plates 54 to contact the slider 45 successively. That is to say, when the slider 45 moves, it can either control the quantitative tubes 50 to pump the suspension into the pressurized filtration chamber 35 first and then pump the inert gas into the pressurized filtration chamber 35, or pump the suspension and the inert gas into the pressurized filtration chamber 35 simultaneously.

[0083] During the solid-liquid separation process of peroxybutanedioic acid, due to the continuous linear reciprocating motion of the slider 45, in the first half of a motion cycle of the slider 45, during the movement of the slider 45, it successively pulls the push plate 54 and the piston to move through the elastic rope 55, causing the suspension and the inert gas to be pumped into the pressurized filtration chamber 35. Since the quantity and capacity of the two groups of metering tubes 50 are determined during the equipment assembly, the total amount of the suspension and the inert gas pumped into the pressurized filtration chamber 35 each time is a fixed value, thus facilitating the orderly progress of the pressurized filtration process. In the second half of a motion cycle of the slider 45, the slider 45 moves in the reverse direction to push the push plate 54 to move, causing the push plate 54 to reset. The metering tubes 50 replenish the inert gas and the suspension under the action of negative pressure air extraction. And during this stage, the conveying roller 37 rotates to change the position of the conveying filter belt 38, thereby realizing the continuous progress of the suspension.

[0084] It should be noted that in this embodiment, there are three groups of metering tubes 50. One group of metering tubes 50 transports dichloromethane with a mass concentration of 99% through a one-way tube 52. And the dichloromethane starts to be pumped after the suspension pumping ends and ends before the inert gas ends. Therefore, when the slider 45 moves, the suspension and the inert gas are first pumped into the pressurized filtration chamber 35. Under the action of air pressure, the solid-liquid separation of the suspension is carried out in cooperation with the conveying filter belt 38. Subsequently, after the suspension pumping stops, dichloromethane is pumped, and the filtered solid is rinsed with dichloromethane. Finally, under the pressurizing action of the inert gas, the separation of dichloromethane and the solid is realized.

[0085] By setting the metering tubes 50 and cooperating with structures such as the dispersion conveying mechanism, the reciprocating lead screw 44, and the slider 45, the present invention can not only achieve the single-time quantitative pumping of the suspension and the inert gas during the drying process of peroxybutanedioic acid, but also make the stages such as gas-liquid pumping, gas-liquid replenishment, and solid-liquid separation proceed in an orderly manner, thereby making the filtration and drying operations of peroxybutanedioic acid continuous and orderly.

[0086] As a preferred embodiment of the present invention, a sealing groove 56 is provided in the kettle body 5. The sealing groove 56 is located between the pressurized filtration chamber 35 and the vacuum filtration chamber 36. A lifting groove 57 is provided in the sealing groove 56. A sealing plate 58 is slidably installed in the lifting groove 57. The sealing plate 58 cooperates with the conveyor belt, the skirt 39, and the baffle 40 to block the sealing groove 56.

[0087] Since the conveying filter belt 38 straddles the pressurized filtration chamber 35 and the vacuum filtration chamber 36, in order to reduce the mutual influence between the two chambers, the sealing plate 58 is used to partition the two chambers, thereby reducing the mutual interference between pressurization and decompression.

[0088] As a preferred embodiment of the present invention, the top end of the sealing plate 58 is slidably and sealingly connected to the lifting groove 57. A telescopic cylinder 59 is installed on the kettle body 5. The telescopic end of the telescopic cylinder 59 is provided with a transmission rod 60. The transmission rod 60 is designed in an F shape. The transmission rod 60 extends to both ends of the reciprocating lead screw 44 and is located on the movement path of the slider 45. The telescopic cylinder 59 is connected to the lifting groove 57 through a pipeline.

[0089] When the slider 45 is moving and gradually approaches the end of the reciprocating lead screw 44, the slider 45 pushes the transmission rod 60 until the transmission rod 60 moves inside the telescopic cylinder 59. At this time, the volume inside the telescopic cylinder 59 changes, and then the fluid in the telescopic cylinder 59 is pumped into the lifting groove 57, forcing the sealing plate 58 to descend. Cooperating with the conveying filter belt 38, the skirt 39, and the baffle 40 to block the sealing groove 56, the pressurized filtration chamber 35 and the vacuum filtration chamber 36 are made not to communicate with each other. Then the slider 45 moves in the reverse direction, causing the metering tube 50 to pump the suspension and inert gas into the pressurized filtration chamber 35. As the slider 45 continues to move, when the slider 45 moves to the other end of the reciprocating lead screw 44, it pushes the transmission rod 60 again, causing the volume inside the telescopic cylinder 59 to increase, forcing the fluid in the lifting groove 57 to flow back into the telescopic cylinder 59, and then the sealing plate 58 rises to facilitate the movement of the conveying filter belt 38.

[0090] The present invention enables the sealing plate 58 to perform periodic lifting, and cooperates with the periodic movement of the conveying filter belt 38, so that the pressurized filtration chamber 35 and the vacuum filtration chamber 36 achieve dynamic sealing, which can not only reduce the mutual obstruction between pressurized filtration and negative pressure filtration, but also enable the processes such as feeding, filtration, and drying to proceed in an orderly manner.

[0091] As a preferred embodiment of the present invention, the conveyor filter belt 38 is located in the middle of the pressurized filtration chamber 35 and the vacuum filtration chamber 36. The metering pipe 50 and the vacuum pump 6 are respectively communicated with the top ends of the pressurized filtration chamber 35 and the vacuum filtration chamber 36. A backwash groove 61 is formed in the kettle body 5, and both ends of the backwash groove 61 are respectively communicated with the bottoms of the pressurized filtration chamber 35 and the vacuum filtration chamber 36. The output end of the vacuum pump 6 is connected to the protective gas tank 34 through a return pipe 62. A gas-liquid separator 63 is installed in the middle of the return pipe 62. The backwash groove 61 is located at the bottoms of the pressurized filtration chamber 35 and the vacuum filtration chamber 36. Therefore, when the sealing plate 58 seals the sealing groove 56, at this time, the suspension and the inert gas are pumped to the top end of the pressurized filtration chamber 35, and then cooperate with the conveyor filter belt 38 to complete solid-liquid separation. At the same time, the vacuum pump 6 continuously acts. Under the conduction action of the backwash groove 61, the negative pressure in the vacuum filtration chamber 36 acts on the bottom of the pressurized filtration chamber 35, promoting the pressure difference between the upper and lower sides of the conveyor filter belt 38 in the pressurized filtration chamber 35 to increase, further accelerating the pressurized filtration effect. When the solid-liquid separation is completed, the excess inert gas passes through the backwash groove 61 and is drawn into the vacuum filtration tank and flows towards the vacuum pump 6. During this process, the inert gas moves from the bottom to the top of the vacuum filtration chamber 36, and then contacts the peroxysuccinic acid particles on the conveyor filter belt 38. It can not only accelerate the separation of the residual moisture on the peroxysuccinic acid by using the air flow, but also impact the pores of the conveyor filter belt 38 by using the air flow, reducing the probability of the conveyor filter belt 38 being blocked. The setting of the return pipe 62 and the gas-liquid separator 63 is used to separate the inert gas and moisture extracted by the vacuum pump 6, and then pump the inert gas back to the protective gas tank 34 again, facilitating the recycling of the inert gas and reducing the consumption of the inert gas to achieve the effect of reducing costs.

[0092] As Figure 2 shown, a system for producing ε-caprolactone includes a peroxidation unit, an oxidation unit, a filtration unit, an acetic acid concentration unit, a precipitation crystallization unit, a light component separation unit and a solvent separation unit. The peroxidation unit, the three-in-one unit, the oxidation unit, the filtration unit, the acetic acid concentration unit, the precipitation crystallization unit, the light component separation unit and the solvent separation unit are connected in series in sequence.

[0093] In this embodiment, the peroxidation unit includes a metering bin 1, a peroxidation reaction tank 2, a first condenser 3, and an oil-water separator 4;

[0094] The peroxidation reaction tank 2 is provided with a 70% hydrogen peroxide feed port, a dichloromethane feed port, a succinic anhydride feed port, a top gas phase outlet, and a material outlet; the succinic anhydride feed port is connected to the metering bin 1; the peroxidation reaction tank 2 is provided with a first condenser 3, and the outlet of the first condenser 3 is connected to the inlet of the oil-water separator 4; the oil phase of the oil-water separator 4 is refluxed to the peroxidation reaction tank 2.

[0095] The oxidation unit includes an oxidation reaction tank 8; the oxidation reaction tank 8 is provided with a cyclohexanone feed port, an acetic acid recycling port, and a peroxysuccinic acid feed port, and the peroxysuccinic acid feed port is connected to a storage bin 7.

[0096] The filtration unit includes a first filter 9 and a first intermediate tank 10; the bottom outlet of the oxidation reaction tank 8 is connected to the inlet of the first filter 9; the outlet of the first filter 9 is connected to the inlet of the first intermediate tank 10.

[0097] The acetic acid concentration unit includes a first transfer pump 11, a first heat exchanger 12, a first distillation column 13, a second condenser 14, a first receiving tank 15, a first reboiler 16, and a second transfer pump 17; the first distillation column 13 is provided with a crude ε-caprolactone feed port, a top gas phase outlet, a reflux material inlet, a bottom product outlet, and a reboiler return port; wherein the liquid in the first intermediate tank 10 is sent to the inlet of the first heat exchanger 12 through the first transfer pump 11, and the outlet of the first heat exchanger 12 is connected to the ε-caprolactone feed port; the top gas phase outlet is connected to the inlet of the second condenser 14 at the top of the first distillation column 13, the outlet of the second condenser 14 is connected to the inlet of the first receiving tank 15, the reflux material inlet is connected to one outlet of the first receiving tank 15, and the other outlet is connected to the acetic acid recycling port of the oxidation reaction tank 8; the bottom product outlet is connected to the inlet of the first reboiler 16 at the bottom of the first distillation column 13 through the second transfer pump 17, and the outlet of the first reboiler 16 is connected to the reboiler return port of the first distillation column 13.

[0098] The precipitation crystallization unit includes a precipitation crystallization tank 18, a second filter 19, and a second intermediate tank 20; the precipitation crystallization tank 18 is provided with a concentrated ε-caprolactone feed port, a cyclohexane recycling port, and a material outlet, wherein the bottom product outlet of the first distillation column 13 is connected to the concentrated ε-caprolactone feed port through the second transfer pump 17; the material outlet is connected to the inlet of the second filter 19; the outlet of the second filter 19 is connected to the second intermediate tank 20.

[0099] [[ID=

[0100] The solvent separation unit includes a third heat exchanger 28, a third distillation column 29, a fourth condenser 30, a third receiving tank 31, a third reboiler 32, and a fifth transfer pump 33; the third distillation column 29 is provided with a light component feed inlet, a top gas phase outlet, a reflux material inlet, a bottom product outlet, and a reboiler return port. Another outlet of the second receiving tank 25 is connected to the inlet of the third heat exchanger 28, and the outlet of the third heat exchanger 28 is connected to the light component feed inlet; the top gas phase outlet is connected to the inlet of the fourth condenser 30 at the top of the third distillation column 29, the outlet of the fourth condenser 30 is connected to the inlet of the third receiving tank 31, the reflux material inlet is connected to one outlet of the third receiving tank 31, and the other outlet is connected to the cyclohexane reuse port of the precipitation crystallization tank 18; the bottom product outlet is connected to the inlet of the third reboiler 32 at the bottom of the third distillation column 29 through the fifth transfer pump 33, and another outlet of the fifth transfer pump 33 is connected to the acetic acid reuse port of the oxidation reaction tank 8; the outlet of the third reboiler 32 is connected to the reboiler return port of the second distillation column 23.

[0101] Succinic anhydride from metering bin 1 is added from the upper part of peroxygenation reaction tank 2. Meanwhile, dichloromethane solvent is injected, and hydrogen peroxide with a mass fraction of 70% is dropped in. Under the azeotropic action of dichloromethane, a low-boiling water-carrying agent, the water generated by the reaction is evaporated from the top of peroxygenation reaction tank 2 and enters the first condenser 3 at the top of peroxygenation reaction tank 2. After condensation, it enters receiving tank 4. After phase separation, water is discharged and dichloromethane is refluxed; the peroxysuccinic acid suspension generated by the reaction is sent to kettle body 5, and solid peroxysuccinic acid is obtained after pressure filtration, washing, and vacuum drying. The solid peroxysuccinic acid is slowly added to the cyclohexanone and acetic acid solvents in oxidation reaction tank 8 for reaction. After the reaction generates succinic acid and is filtered in the first filter 9, the resulting solution is a crude ε-caprolactone solution. The solution is sent to the first rectification column 13. Low-boiling acetic acid is evaporated from the top of the column and enters the second condenser 14 at the top of the column. After condensation, a part of it is refluxed in the first receiving tank 15, and a part of it is used as the solvent for oxidation reaction tank 8; a part of the solution at the bottom of the column is heated by the first reboiler 16 and then returned to the first rectification column 13, and a part of it is taken out to obtain a concentrated ε-caprolactone solution. The solution taken out from the bottom of the column is sent to the precipitation crystallization tank 18. After adding cyclohexane, the precipitated crystals are filtered in the second filter 19, and the ε-caprolactone solution with heavy components removed is stored in the second intermediate tank 20 for buffering. The solution in the second intermediate tank 20 is sent to the second rectification column 23 through the third transfer pump 21 after being heated by the heater 22. Light components are evaporated from the top of the column and enter the third condenser 24 at the top of the column. After condensation, a part of it is refluxed in the second receiving tank 25, and a part of it is sent to the next process for further separation; a part of the solution at the bottom of the column is heated by the second reboiler 26 and then returned to the second rectification column 23, and a part of it is taken out to obtain the finished product ε-caprolactone. The light components are heated by the third heat exchanger 28 and then sent to the third rectification column 29. Low-boiling cyclohexanone is evaporated from the top of the column and enters the fourth condenser 30 at the top of the column. After condensation, a part of it is refluxed in the third receiving tank 31, and a part of it is used as the precipitation mixed solvent for precipitation crystallization tank 18; a part of the solution at the bottom of the column is heated by the third reboiler 32 and then returned to the third rectification column 29, and a part of it is taken out to obtain acetic acid as the solvent for oxidation reaction tank 8.

[0102] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A process for producing ε-caprolactone, characterized in that, It includes the following steps: A1. Peroxidation reaction: Succinic anhydride is put into dichloromethane solution, and hydrogen peroxide with a concentration of 70% is slowly added dropwise. After continuous stirring and reaction, a suspension containing solid peroxybutyric acid is obtained; A2. Tri-in-one process: The suspension prepared in A1 is transferred into a tri-in-one unit, pressurized and filtered under the protection of inert gas in a pressurized filtration chamber (35), and then vacuum filtered in a vacuum filtration chamber (36) to obtain dry peroxybutyric acid solid; A3. Oxidation reaction: The dry peroxybutyric acid solid is slowly added to cyclohexanone and acetic acid solvents, stirred and reacted to obtain an ε-caprolactone solution with a mass concentration of 7%-20%; A4. Filtration process: The ε-caprolactone solution prepared in A3 is cooled to room temperature, and the generated succinic acid solid is filtered out to obtain a clarified solution as the ε-caprolactone solution; A5. Acetic acid concentration process: The ε-caprolactone solution prepared in A4 is rectified and concentrated under reduced pressure until the proportion of acetic acid solvent in the ε-caprolactone solution reaches 40%-50%; A6. Anti-solvent crystallization process: The concentrated solution in A5 is further filtered to remove succinic acid solid to obtain a clarified ε-caprolactone solution with heavy components removed; A7. Separation process: The ε-caprolactone solution prepared in A6 is subjected to rectification separation operation to obtain high-purity ε-caprolactone; Wherein the tri-in-one unit described in A2 includes a kettle body (5), a protective gas tank (34) and a vacuum pump (6); A pressurized filtration chamber (35) and a vacuum filtration chamber (36) are arranged in the kettle body (5); The protective gas tank (34) and the vacuum pump (6) are both installed on the kettle body (5). The protective gas tank (34) stores inert protective gas, and the protective gas tank (34) is used to pump inert protective gas into the pressurized filtration chamber (35). The input end of the vacuum pump (6) is conductively connected to the vacuum filtration chamber (36); A dispersion and transportation mechanism is installed in the pressurized filtration chamber (35) and the vacuum filtration chamber (36), and the dispersion and transportation mechanism is used to disperse, transport and filter the suspension.

2. The process for producing ε-caprolactone according to claim 1, characterized in that: Wherein before the solution in A6 is subjected to filtration operation, cyclohexane also needs to be added to the solution, and the molar ratio of cyclohexane to acetic acid is 1:3 - 1:

5.

3. A process for producing ε-caprolactone according to claim 1, characterized in that: It also includes A8. Re-separation process: The light components taken out from the top of the rectification tower in A7 are subjected to rectification separation operation again. The rectification temperature is controlled at 50 - 80 °C and the pressure is 1 - 20 kPa. After rectification, low-boiling cyclohexane is taken out from the top of the tower and high-boiling acetic acid is taken out from the bottom of the tower and returned for reuse.

4. A process for producing ε-caprolactone according to claim 1, characterized in that: The dispersion and transportation mechanism includes a conveying roller (37), a conveying filter belt (38), a skirt (39) and a baffle (40); The conveying roller (37) is rotatably installed on the kettle body (5), and the conveying filter belt (38) is sleeved and installed on the conveying roller (37) together. The conveying filter belt (38) is made of high-precision filter cloth material; Skirts (39) are fixedly installed on both sides of the conveying filter belt (38), and baffles (40) are fixedly installed at uniform intervals along the length direction of the conveying filter belt (38). The skirts (39) and the baffles (40) cooperate with the conveying filter belt (38) to form a plurality of dispersion grooves (41). A circulation groove (42) is formed in the kettle body (5). The conveying filter belt (38) and the skirts (39) extend into the circulation groove (42). The conveying filter belt (38) cooperates with the skirts (39) to separate the upper and lower sides of the pressurized filtration chamber (35) and the vacuum filtration chamber (36).

5. A process for producing ε-caprolactone according to claim 4, characterized in that: A driving motor (43) is fixedly installed on the kettle body (5). A reciprocating lead screw (44) is fixedly installed at the output end of the driving motor (43). A slider (45) is installed on the reciprocating lead screw (44), and the slider (45) is in screw drive with the reciprocating lead screw (44). A driving wheel (46) is installed on the kettle body (5). The driving wheel (46) is fixedly connected to the conveying roller (37). A transmission plate (47) is fixedly installed on the slider (45). Uniformly distributed deflection grooves (48) are formed in the transmission plate (47). Ratchet teeth (49) are hinged and installed in the deflection grooves (48) through torsion springs. The transmission plate (47) is in one-way drive with the driving wheel (46) through the ratchet teeth (49).

6. A process for producing ε-caprolactone according to claim 5, characterized in that: At least two groups of metering tubes (50) are fixedly installed on the kettle body (5). The two groups of metering tubes (50) are both connected to the pressurized filtration chamber (35) through one-way valve tubes (51). The two groups of metering tubes (50) are respectively externally connected to a protective gas tank (34) and a peroxidation reaction tank (8)(2) through one-way tubes (52). Sealing pistons (53) are installed in the metering tubes (50). Push plates (54) are fixedly installed on the sealing pistons (53). The push plates (54) all extend to the movement path of the slider (45), and the push plates (54) are elastically connected to the slider (45) through elastic ropes (55).

7. A process for producing ε-caprolactone according to claim 6, characterized in that: A sealing groove (56) is formed in the kettle body (5). The sealing groove (56) is located between the pressurized filtration chamber (35) and the vacuum filtration chamber (36). A lifting groove (57) is formed in the sealing groove (56). A sealing plate (58) is slidably installed in the lifting groove (57). The sealing plate (58) cooperates with the conveyor belt, the skirts (39), and the baffles (40) to block the sealing groove (56).

8. A process for producing ε-caprolactone according to claim 7, characterized in that: The top end of the sealing plate (58) is slidably and sealedly connected to the lifting groove (57). A telescopic cylinder (59) is installed on the kettle body (5). A transmission rod (60) is installed at the telescopic end of the telescopic cylinder (59). The transmission rod (60) is designed in an F shape. The transmission rod (60) extends to both ends of the reciprocating lead screw (44) and is located on the movement path of the slider (45). The telescopic cylinder (59) is connected to the lifting groove (57) through a pipeline.

9. A process for producing ε-caprolactone according to claim 8, characterized in that: The conveying filter belt (38) is located in the middle of the pressurized filtration chamber (35) and the vacuum filtration chamber (36). The metering pipe (50) and the vacuum pump (6) are respectively communicated with the tops of the pressurized filtration chamber (35) and the vacuum filtration chamber (36). A backwashing groove (61) is formed in the kettle body (5), and both ends of the backwashing groove (61) are respectively communicated with the bottoms of the pressurized filtration chamber (35) and the vacuum filtration chamber (36). The output end of the vacuum pump (6) is communicated with the protective gas tank (34) through a reflux pipe (62), and a gas-liquid separator (63) is installed in the middle of the reflux pipe (62).

10. A system for producing ε-caprolactone based on the process for producing ε-caprolactone described in claim 9, characterized in that: It includes a peroxidation unit, a three-in-one unit, an oxidation unit, a filtration unit, an acetic acid concentration unit, a precipitation crystallization unit, a light component separation unit and a solvent separation unit. The peroxidation unit, the three-in-one unit, the oxidation unit, the filtration unit, the acetic acid concentration unit, the precipitation crystallization unit, the light component separation unit and the solvent separation unit are connected in series in sequence.

Images