Epoxy propane reaction device

Abstract

The invention relates to the technical field of production of epoxypropane by a hydrogen peroxide method, in particular to an epoxypropane reaction device which comprises a cylinder, a funnel and a downcomer, and the downcomer can be opened and closed; the reaction tube is wound around the cylinder, the tube diameter of the reaction tube is gradually increased from bottom to top, the upper end of the reaction tube is connected with the funnel, and the downcomer is connected with the reaction tube. The hydrogen peroxide reaction device has the following beneficial effects that through good temperature control, the utilization rate of hydrogen peroxide is increased, the service life of a catalyst is prolonged, potential safety hazards are reduced, and the production cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of producing propylene oxide by hydrogen peroxide method, in particular to a propylene oxide reaction device. Background Art

[0002] The main production processes of propylene oxide include the chlorohydrin method, co-oxidation method, cumene oxidation method and direct hydrogen peroxide oxidation method (HPPO method). Among them, the HPPO method is a common method. The process is: methanol, propylene and hydrogen peroxide are added to a reactor containing a zeolite titanium silicate catalyst in a certain proportion, and a selective oxidation reaction occurs under low temperature and low pressure conditions to generate propylene oxide in one step. This method has the following advantages: green and environmentally friendly, the only by-product after the reaction is water, which is environmentally friendly and in line with the development trend of modern chemical industry; short process, simple process, relatively easy operation and control; high atomic utilization, low investment, low energy consumption, high product yield and few other by-products.

[0003] At the same time, the HPPO method for producing hydrogen peroxide also has the following disadvantages:

[0004] 1. Under high temperature reaction conditions, most of the hydrogen peroxide will self-decompose into oxygen and water. When the temperature is 60°C, the decomposition rate of hydrogen peroxide is about 50%. When the temperature reaches 90-100°C, hydrogen peroxide can be decomposed by 90%. When heated to above 100°C, hydrogen peroxide begins to decompose rapidly, resulting in a waste of hydrogen peroxide and high production costs;

[0005] 2. The performance and life of the catalyst have a great impact on the stability and economy of the process. Currently, the research and development and improvement of the catalyst are still ongoing;

[0006] 3. The heat transfer and mass transfer process of the HPPO method is the key factor that limits product quality and leads to high operating costs. Excessive local temperature will not only shorten the catalyst life and produce a large amount of by-products, but also easily cause production hazards such as explosions. Therefore, local overheating can easily reduce product quality and increase subsequent separation costs on the one hand, and cause safety accidents on the other.

[0007] In order to overcome the above shortcomings, the patent with announcement number CN104130216B discloses a process for continuous production of propylene oxide by direct oxidation of propylene / propane mixed gas with hydrogen peroxide. A fluidized bed loop reactor is used in the reaction process, and a fine-grained molecular sieve catalyst is applied. The slurry discharge passes through a flash tower to evaporate low-oxygen propylene / propane mixed gas and propylene oxide respectively, and the catalyst-containing mother liquor passes through a membrane separator to separate the catalyst slurry and the mother liquor. After the mother liquor is flashed to separate methanol, the solvent methanol is recovered to synchronously recover the residual high-oxygen propylene / propane mixed gas after the reaction in a high-oxygen propylene / propane absorption tower for recycling, and the catalyst slurry is returned to the reactor for recycling after partial online regeneration. The fluidized bed used in the method adopted by this patent cannot effectively transfer the reaction heat, and the reaction product and the reaction material are seriously mixed, the reaction efficiency is low, and the side reaction is increased.

[0008] The patent with publication number CN117504739A discloses a propylene oxide preparation device and preparation method. The propylene oxide preparation device adopts a tubular upflow circulating slurry bed reactor, a catalyst circulation mechanism and a product separator, and a plurality of submerged heat exchangers are arranged in the upflow circulating slurry bed reactor; the submerged heat exchanger includes an outer tube manifold, an inner tube manifold, and a plurality of sets of outer tubes and inner tubes, and a reflux channel is reserved between the outer tubes and the inner tubes, one end of all the outer tubes is closed, and the other end is connected to the outer tube manifold; one end of all the inner tubes close to the closed end of the outer tube is open, and the other end is connected to the inner tube manifold; the outer tube manifold is connected to the external environment through the medium inlet pipe; the inner tube manifold is connected to the external environment through the medium outlet pipe. Although this patent adopts a heat transfer reaction similar to a shell-and-tube heat exchanger, which can effectively remove the heat from the reaction and prevent the generation of overheating sites, the device adds separation equipment and related operations for materials and catalysts, which increases operating costs; and due to the collection and regeneration of catalysts, the equipment is loose and difficult to control. As the number of times the catalyst is used increases, the carrier is damaged, and the particles are no longer uniform in size, but vary in size, making the fluidized state difficult to control. If the flow rate is fast, small particles will be washed away, and if the flow rate is slow, the fluidized state cannot be formed. Summary of the invention

[0009] The object of the present invention is to provide a propylene oxide reaction device, which has the characteristics of reasonable temperature control, high catalyst utilization rate and low production cost.

[0010] The above technical objectives of the present invention are achieved through the following technical solutions: A propylene oxide reaction device, comprising:

[0011] The cylinder includes a funnel and a downcomer, and the downcomer can be opened and closed;

[0012] The reaction tube is arranged in a coiled cylinder, the diameter of the reaction tube increases gradually from bottom to top, the upper end of the reaction tube is connected to the funnel, and the downcomer is connected to the reaction tube.

[0013] Preferably, a fabric is provided above the funnel, a metal sieve plate with a heating function is provided below the fabric, a straight rod is connected to the bottom of the fabric, the straight rod extends into the downcomer and is connected to a sphere, the downcomer includes an upper section, a middle section, and a lower section connected in sequence from top to bottom, and the size relationship thereof is: the maximum diameter of the middle section > the diameter of the upper section > the diameter of the sphere > the diameter of the lower section, the sphere is located in the middle section and closes the entrance of the lower section.

[0014] Preferably, a storage chamber is connected to the bottom of the downcomer, and a capillary tube is connected to the storage chamber and the reaction tube.

[0015] Preferably, the connection between the capillary tube and the reaction tube is close to the lower end of the reaction tube.

[0016] Preferably, the upper end of the reaction tube is tangentially connected to the side of the funnel.

[0017] Preferably, a heating metal plate is provided below the funnel.

[0018] Preferably, a plurality of heating screen plates are arranged above the fabric, a plurality of mushroom-shaped air pipes are arranged on each heating screen plate, and a drainage pipe is arranged above each heating plate.

[0019] Preferably, a jacket is provided on the outside of the reaction tube, and the jacket has a water inlet and a water outlet.

[0020] Preferably, the diameter of the highest point of the reaction tube is 2 to 5 times the diameter of the lowest point, and the connection between the reaction tube and the funnel is closed, and the diameter of the connection between the reaction tube and the funnel is 0.5 to 0.8 times the diameter of the lower end.

[0021] A control method for a propylene oxide reaction device is characterized in that the temperature of a metal sieve plate is controlled by programmed heating and cooling, wherein the heating rate is 1-2°C / min, after the temperature is raised to 45°C, the heating rate is increased to 5°C / min, and after the temperature reaches 65-70°C, the heating is stopped, and after the temperature is naturally cooled to 38°C, the heating is continued at a rate of 1-2°C / min, and the heating process is repeated.

[0022] In summary, the present invention has the following beneficial effects:

[0023] 1. The reaction tube of this device adopts microchannel reaction technology. The heat generated by the reaction will not be concentrated or accumulated locally, but will gradually disperse along a very long channel. Because the pipeline is long, the contact area between the pipeline and the outside world is increased, which is more conducive to heat dissipation;

[0024] 2. The reaction tube in this device is thin at the lower section and gradually becomes thicker at the upper section. The flow rate of the reaction raw material liquid in it gradually slows down. The catalyst particles are retained to form a natural separation process. The amount of catalyst entering the separation part is greatly reduced, avoiding mechanical stirring in traditional processes and reducing the breakage loss of the catalyst.

[0025] 3. The catalyst regeneration process in the device is simple, the catalyst particles and the reaction liquid are naturally separated, there is little backmixing between the materials, and no manual control is required;

[0026] 4. The fluidization velocity in the reaction tube is naturally controllable, and the particles can naturally stay at different flow rates without chaotic flow due to catalyst damage or uneven particles;

[0027] 5. This device can effectively control the back-mixing of materials. When a sufficient amount of particles are accumulated, the reflux path is connected to prevent the back-mixing of materials, and it can be automatically controlled;

[0028] 6. Since the reaction takes place in a long and narrow tube such as a reaction tube, propane and hydrogen peroxide are fully mixed, which can greatly reduce the amount of methanol used, saving costs and reducing the cost of subsequent separation operations;

[0029] 7. The temperature in the reaction tube is low, at about 30°C, which avoids the large-scale decomposition of hydrogen peroxide under high temperature conditions, increases the utilization rate of hydrogen peroxide, and effectively reduces production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the structure of the device;

[0031] Figure 2 It is a cross-sectional view of the cylinder along the vertical direction;

[0032] Figure 3 It is a schematic diagram of the structure of the funnel;

[0033] Figure 4 It is a schematic diagram of the structure of the downcomer.

[0034] In the figure, 1. cylinder; 2. reaction tube; 21. material inlet; 22. material outlet; 3. jacket; 31. water inlet; 32. water outlet; 4. funnel; 41. heating metal plate; 42. downcomer; 421. upper section; 422. middle section; 423. lower section; 5. metal sieve plate; 6. fabric; 7. straight rod; 8. sphere; 9. storage chamber; 10. capillary; 11. heating sieve plate; 111. air pipe; 12. drain pipe. DETAILED DESCRIPTION

[0035] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0036] This specific embodiment is merely an explanation of the present invention and is not a limitation of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed. However, as long as they are within the scope of the claims of the present invention, they are protected by the patent law.

[0037] Example:

[0038] like Figure 1 As shown, the device comprises an upright cylinder 1, and a reaction tube 2 is wound around the middle and lower ends of the outer side of the cylinder 1. The diameters of the reaction tubes 2 are not of the same size. The lower part is thinner, about 1 to 2 cm. As it winds upward, the diameter gradually increases, and the diameter of the highest point is 2 to 5 times the diameter of the lowest point. In this embodiment, the diameter of the thinnest part of the lower end of the reaction tube 2 is 1 cm, and the diameter of the thickest part of the upper end of the reaction tube 2 is 5 cm. A jacket 3 is arranged on the outer side of the reaction tube 2, and the jacket 3 is provided with a water inlet 31 and a water outlet 32. The lower end of the reaction tube 2 is a material inlet 21, and the material inlet 21 extends outside the jacket 3. The upper end of the reaction tube 2 is the outlet of the reaction material, and the upper end is connected to the inside of the cylinder 1. Inside the cylinder 1, the reaction tube 2 is closed, and the diameter is reduced to 0.5 to 0.8 times the diameter of the lower end inlet, and a jet is formed at the outlet. In this embodiment, the diameter of the upper end of the reaction tube 2 is reduced to 0.5 cm.

[0039] like Figure 2 As shown, a funnel 4 is arranged inside the cylinder 1. The funnel 4 is as shown in FIG. Figure 3 As shown, the side of the funnel 4 has a material outlet 22 connected to the upper end of the reaction tube 2. The upper end of the reaction tube 2 is located at the middle and lower end of the funnel 4 and is tangent to the circle where the horizontal plane is located. The bottom of the funnel 4 is connected to a downcomer 42. The downcomer 42 is as shown in FIG. Figure 4 As shown, the downcomer 42 includes an upper section 421, a middle section 422, and a lower section 423. The upper section 421 is relatively long and thick, with a diameter of 3 to 6 cm; the diameter of the middle section 422 is 8 to 10 cm; and the diameter of the lower section 423 is 1 to 3 cm. A sphere 8 is arranged in the middle section 422, and the diameter of the sphere 8 is 3 to 4 cm. When used, the diameter of the middle section 422 is larger than the diameter of the sphere 8, the diameter of the sphere 8 is larger than the diameter of the lower section 423, and the diameter of the upper section 421 is larger than the diameter of the sphere 8 and smaller than the diameter of the middle section 422. In this embodiment, the diameter of the upper section 421 is 4 cm, and the diameter of the lower section 423 is 2 cm. The upper and lower ends of the middle section 422 are connected to the upper section 421 and the lower section 423 respectively, and its diameter increases first and then decreases from top to bottom, and its maximum diameter is 9 cm. The diameter of the sphere 8 is 3 cm.

[0040] like Figure 2As shown, the surface where the upper edge of the funnel 4 is located is a horizontal plane, and the upper edge is connected to the inner wall of the cylinder 1. A metal sieve plate 5 with a program heating function is provided at the large mouth of the funnel 4, and a filtering fabric 6 is horizontally suspended above the metal sieve plate 5. The edge of the fabric 6 is circular and connected to the inner wall of the cylinder 1. A straight rod 7 is suspended downward from the center of the fabric 6. The straight rod 7 passes through the center of the metal sieve plate 5 and extends downward directly into the downcomer 42, and is connected to the sphere 8. The sphere 8 is located in the middle section 422 of the downcomer 42. When the funnel 4 is filled with reaction liquid, the sphere 8 is in a sinking state due to its own gravity, and the fabric 6 is brought downward to form a concave surface.

[0041] A heating metal plate 41 is provided below the funnel 4 to maintain the temperature at 55-60°C.

[0042] When the sphere 8 naturally descends, it blocks the pipe opening of the lower section 423 of the downcomer 42 , so that the catalyst can be deposited in the downcomer 42 .

[0043] A conical storage chamber 9 is connected below the downcomer 42 , a capillary tube 10 is connected below the storage chamber 9 , and the capillary tube 10 is connected outward to the lower end of the reaction tube 2 near the material inlet 21 .

[0044] A plurality of heating sieve plates 11 are arranged above the fabric 6. In this embodiment, three heating sieve plates 11 are arranged, namely, the first sieve plate, the second sieve plate, and the third sieve plate from bottom to top. The structures of the heating sieve plates 11 are the same.

[0045] The heating sieve plate 11 has a heating function and can be kept constant at a certain temperature. A plurality of mushroom-shaped air pipes 111 are respectively arranged on each heating sieve plate. The gas can pass through the air pipes 111 from bottom to top, escape from under the mushroom heads of the air pipes 111, and then condense and drip onto the surface of the heating sieve plate 11. A drain pipe 12 is arranged above the heating sieve plate 11, and the condensed liquid can be directly discharged from the drain pipe 12; a drain pipe 12 is arranged on the upper side of each heating sieve plate 11.

[0046] The temperature of the metal sieve plate 5 is controlled by programmed heating and cooling, and the heating rate is 1-2°C / min. After it is heated to 45°C, the heating rate is increased to 5°C / min. After the temperature reaches 65-70°C, the heating is stopped, and it is naturally cooled to 38°C and then continued to be heated at a rate of 1-2°C / min. The heating process is repeated. In this process, the heating rate is suddenly increased, which can expand the gas under the fabric 6, drive the sphere 8 to move upward, and make the catalyst intercepted in the downcomer 42 descend into the storage chamber 9, and then slowly slide from the capillary 10 into the reaction tube 2. The negative pressure generated by the flow of material in the reaction tube 2 can suck the material in the capillary 10 into the reaction tube 2.

[0047] The temperature in the jacket 3 of the reaction tube 2 is controlled at 32-34° C., and the pressure is normal pressure.

[0048] The temperature of the first sieve plate is controlled at 55-60°C, the temperature of the second sieve plate is controlled at 35-38°C, and the temperature of the third sieve plate is controlled at 20-25°C. The temperatures of the first, second, and third sieve plates are gradually reduced to room temperature to liquefy the organic gas at the top.

[0049] The composition of the reaction liquid is that the molar ratio of propylene to hydrogen peroxide is (1-1.5):1; the molar ratio of methanol to hydrogen peroxide is (1.0-3):1, and the flow rate of the reaction liquid at the lower end inlet of the reaction tube is 0.5-1m / s.

[0050] At the beginning of the reaction, a catalyst with a particle size of 0.5 to 4 mm is added to the reaction liquid. The catalyst is commercially available and mixed in the reaction liquid and pumped into the reaction tube 2 by a pump. The particles move and react in the reaction tube 2. As the diameter of the reaction tube 2 becomes larger and larger, the flow rate of the reaction liquid becomes slower and slower. The particles stay in the reaction tube 2. Some smaller particles flow out of the reaction liquid into the funnel 4 and settle in the downcomer 42 in the funnel 4. Since the hollow ball 8 blocks the entrance of the lower section 423 of the downcomer 42, the particles They gather in the upper section 421 of the downcomer 42. As the temperature of the metal sieve plate 5 rises, the propylene oxide, methanol and unreacted propane in the reaction liquid are evaporated and pass through the fabric 6 to enter the upper condensation part. As the heating speed varies, the airflow drives the fabric 6 to shake, thereby driving the ball 8 to move, causing the ball 8 to leave the entrance of the lower section 423, and causing the catalyst precipitated in the downcomer 42 to fall into the storage chamber 9. Subsequently, as the reaction liquid in the reaction tube 2 continues to flow, it returns to the reaction tube 2 and circulates to participate in the reaction.

[0051] The outlet at the upper end of the reaction tube 2 is closed and enters the funnel 4 at a tangent angle. The reaction liquid rotates rapidly in the funnel 4 to form an evaporation surface to accelerate evaporation.

[0052] The evaporated reaction liquid vapor is cooled and liquefied step by step through the first sieve plate, the second sieve plate and the third sieve plate, and the desired product is discharged from the drain pipe 12, and the gas that cannot be condensed is discharged from the top exhaust port of the cylinder 1 for treatment.

Claims

1. A propylene oxide reaction device, characterized in that: include: The cylinder (1) comprises a funnel (4) and a downcomer (42), wherein the downcomer (42) can be opened and closed; The reaction tube (2) is arranged to coil around the cylinder (1), the diameter of the reaction tube (2) gradually increases from bottom to top, the upper end of the reaction tube (2) is connected to the funnel (4), and the downcomer (42) is connected to the reaction tube (2).

2. A propylene oxide reaction device according to claim 1, characterized in that: A fabric (6) is arranged above the funnel (4), a metal sieve plate (5) with a heating function is arranged below the fabric (6), a straight rod (7) is connected to the bottom of the fabric (6), the straight rod (7) extends into the downcomer (42) and is connected to a sphere (8), the downcomer (42) comprises an upper section (421), a middle section (422), and a lower section (423) which are connected in sequence from top to bottom, and the size relationship thereof is: the maximum diameter of the middle section (422)>the diameter of the upper section (421)>the diameter of the sphere (8)>the diameter of the lower section (423), the sphere (8) is located in the middle section (422) and closes the entrance of the lower section (423).

3. A propylene oxide reaction device according to claim 1, characterized in that: The bottom of the downcomer (42) is connected to a storage chamber (9), and the storage chamber (9) is connected to the reaction tube (2) via a capillary tube (10).

4. A propylene oxide reaction device according to claim 3, characterized in that: The connection between the capillary tube (10) and the reaction tube (2) is close to the lower end of the reaction tube (2).

5. A propylene oxide reaction device according to claim 1, characterized in that: The upper end of the reaction tube (2) is connected to the side of the funnel (4) along the tangential direction.

6. A propylene oxide reaction device according to claim 1, characterized in that: A heating metal plate (41) is arranged below the funnel (4).

7. A propylene oxide reaction device according to claim 1, characterized in that: A plurality of heating screen plates (11) are arranged above the fabric (6), a plurality of mushroom-shaped air pipes (111) are arranged on each heating screen plate (11), and a liquid discharge pipe (12) is arranged above each heating plate.

8. A propylene oxide reaction device according to claim 1, characterized in that: A jacket (3) is arranged on the outside of the reaction tube (2), and the jacket (3) has a water inlet (31) and a water outlet (32).

9. A propylene oxide reaction device according to claim 1, characterized in that: The diameter of the highest point of the reaction tube (2) is 2 to 5 times the diameter of the lowest point. The connection between the reaction tube (2) and the funnel (4) is closed, and the diameter of the connection between the reaction tube (2) and the funnel (4) is 0.5 to 0.8 times the diameter of the lower end.

10. The control method of a propylene oxide reaction device according to claim 2, characterized in that: The temperature of the metal sieve plate (5) is controlled by programmed heating and cooling, wherein the heating rate is 1-2°C / min. After the temperature reaches 45°C, the heating rate is increased to 5°C / min. After the temperature reaches 65-70°C, the heating is stopped, and the temperature is naturally cooled to 38°C before continuing to be heated at a rate of 1-2°C / min. The heating process is repeated.

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