An oxidation device for producing hydrogen peroxide

Abstract

The present invention discloses an oxidation device for producing hydrogen peroxide, which includes an oxidation tower (101). On both sides of the lower part of the oxidation tower (101), there are respectively a gas inlet A (111) and a liquid inlet A (112). At the top, there is a gas outlet A (113), and on the upper side, there is a liquid outlet A (114). Inside the oxidation tower (101), there are a gas-liquid separator (103), a gas distributor (104), and segmental trays (102). The liquid inlet A (112) is located below the gas distributor (104). The segmental trays (102) are provided with uniformly distributed holes, and adjacent segmental trays (102) are alternately distributed. In the present invention, air and the working liquid enter the oxidation tower from the lower part of the oxidation tower, and macroscopically flow upward in parallel and react inside. However, due to the influence of the segmental trays, the working liquid flows in an S-shaped crossflow inside the oxidation tower, the flow path of the working liquid in the oxidation tower is lengthened, and the gas and liquid can contact more fully, which is beneficial to improving the conversion rate of the reaction.

Description

Technical Field

[0001] The present invention relates to a device and process for gas-liquid two-phase reaction, and particularly to an oxidation device for producing hydrogen peroxide. Background Art

[0002] At present, the anthraquinone process is mainly used to prepare hydrogen peroxide at home and abroad. In this process, alkyl anthraquinone (AQ, mainly 2-alkyl anthraquinone) is used as a carrier, and a suitable solvent for dissolving anthraquinone and anthrahydroquinone and a substance for adjusting the pH of the solution are selected to form a working solution together. The whole preparation process generally includes hydrogenation, oxidation, extraction, purification and other processes. The solvent for dissolving anthraquinone is generally heavy aromatic hydrocarbons extracted from the petroleum industry. In China, C9 aromatic hydrocarbons are mostly used, which is a mixture containing mesitylene, methyl ethyl benzene, etc., while in foreign countries, C10 aromatic hydrocarbons are mostly used. The solvent for dissolving anthrahydroquinone can be selected from one or more of o-methyl cyclohexyl acetate, diisobutyl methanol, trioctyl phosphate, tetrabutyl urea, etc. In the hydrogenation process, anthraquinone is hydrogenated to anthrahydroquinone under the action of a catalyst, and the working solution also becomes a hydrogenated solution. Then, the hydrogenated solution is oxidized by a gas containing oxygen to an oxidized solution containing H2O2 and anthraquinone in the oxidation process. The gas containing oxygen can be pure oxygen or oxygen-enriched air. In industrial practice, compressed air is mostly selected for cost reduction and safety considerations.

[0003] In the oxidation process, the hydrogenated solution and air generally react in a co-current upward flow manner. Since the oxygen content in the air is only about 21%, the reaction pressure in the oxidation tower is 0.18 - 0.4 MPa, and the reaction temperature is 40 - 55 °C. The reaction conditions are relatively mild, the oxygen concentration at the gas-liquid interface is also low, and the reaction rate is slow. In order to improve the reaction conversion rate, the industrial reaction is carried out in a way of two towers in series or three towers in series. In the tower, except for the gas distributor, redistributor, and heat exchanger, it is mainly an empty tower. Even after a long reaction time in the oxidation tower, the oxidation yield is still only about 90 - 95%, and the tail oxygen content is about 6%. At present, there are disadvantages in industry such as low oxidation yield and high tail oxygen content. Summary of the Invention

[0004] The object of the present invention is to provide an oxidation device for producing hydrogen peroxide. After the air and the working solution enter the oxidation tower from the lower part of the oxidation tower, they macroscopically flow upward in a co-current manner and react in the oxidation tower. However, due to the influence of the bow-shaped tray, the working solution flows in an S-shaped cross-flow manner in the oxidation tower, the flow path of the working solution in the oxidation tower is lengthened, and the gas and liquid can contact more fully, which is beneficial to improving the reaction conversion rate. In addition, the air at the outlet of the oxidation tower can significantly reduce the tail oxygen content after passing through the pre-reactor, and the working solution at the outlet of the oxidation tower can significantly improve the conversion rate of the hydrogenated solution and the yield of hydrogen peroxide after passing through the post-reactor, thereby improving the economic benefits of the whole device.

[0005] The object of the present invention is achieved by the following technical solutions:

[0006] An oxidation device for producing hydrogen peroxide, comprising an oxidation tower 101, characterized in that gas inlet A 111 and liquid inlet A 112 are respectively arranged on both sides of the lower part of the oxidation tower 101, a gas outlet A 113 is arranged at the top, and a liquid outlet A 114 is arranged on the upper side surface. A gas-liquid separator 103, a gas distributor 104, and segmental trays 102 are arranged in the oxidation tower 101. The liquid inlet A 112 is located below the gas distributor 104. The segmental trays 102 are provided with evenly distributed holes, and adjacent segmental trays 102 are alternately distributed.

[0007] Preferably, the first segmental tray 102 above the gas distributor 104 is 1 - 5 m away from the gas distributor 104, and the distance between adjacent segmental trays 102 is 30 cm - 200 cm.

[0008] Preferably, the length of the chord 1021 of the segmental tray 102 accounts for 20% - 90% of the diameter of the oxidation tower 101, and the area of the segmental tray 102 accounts for more than half of the cross-sectional area of the oxidation tower 101.

[0009] Preferably, the holes evenly distributed on the segmental tray 102 are circular or tongue-shaped. The size of the circular holes is 1 mm - 30 mm, and the hole opening rate is 0.1% - 10%; the hole opening rate of the tongue-shaped holes is 0.1% - 10%.

[0010] Preferably, the gas inlets of the oxidation tower 101 are 1 - 10, and are arranged successively from the bottom to the top on the side surface of the oxidation tower 101; more preferably, there are 3 gas inlets, which are respectively located at the bottom of the side surface of the oxidation tower 101, the 1 / 2 height position of the side surface of the oxidation tower 101, and the 3 / 4 height position; preferably, each gas inlet is provided with a gas distributor.

[0011] Preferably, the liquid feed flow rate does not exceed 1 m / s.

[0012] Preferably, the gas distributor 104 is a gas distributor with circular holes. The size of the holes of the gas distributor 104 is 20 μm - 1000 μm, and the perforation flow rate is 0.1 m / s - 10 m / s. More preferably, the size of the holes is 20 - 100 μm.

[0013] Preferably, the gas distributor 104 is a gas distributor with a microporous structure. The microporous structure includes a metal sintered microporous tube, a ceramic sintered microporous tube, a microporous membrane, a microporous membrane tube, or a microchannel with a pore diameter of 0.01 - 50 μm. The gas distributor 104 enters the oxidation tower 101 with gas in the form of microbubbles through the microporous structure.

[0014] Preferably, the oxidation device is provided with a microbubble generator 201 and a post-reactor 202. The oxidation liquid flowing out from the liquid outlet A 114 of the oxidation tower 101 and part of the fresh air are mixed by the microbubble generator 201 to form a microbubble flow and enter the post-reactor 202. The gas coming out from the top of the post-reactor 202 is mixed with the fresh air and then enters the oxidation tower 101.

[0015] Preferably, the oxidation liquid flowing out from the post-reactor 202 enters a heat exchanger or the next process step.

[0016] Preferably, the amount of fresh air entering the microbubble generator 201 does not exceed 50% of the total air volume of the oxidation tower 101, and is preferably 10 - 30%.

[0017] Preferably, the microbubble generator 201 is made of a Venturi injector, a sintered metal microporous tube, a sintered ceramic microporous tube, a microporous plate, a microporous membrane, etc., or forms a microbubble flow through the pressurized dissolved air gas release method or the tangential swirl method.

[0018] Preferably, the oxidation device is provided with a pre-reactor 301. The upper side of the pre-reactor 301 is provided with a liquid inlet B 311, the top is provided with a gas outlet B 312, the bottom is provided with a gas inlet B 313, and the lower side of the side is provided with a liquid outlet B 314. The gas coming out from the oxidation tower 101 enters from the bottom of the pre-reactor 301 and reacts with the working liquid. The reacted gas enters the oxidation tail gas condenser; preferably, 10 - 100% of the gas coming out from the oxidation tower 101 enters the pre-reactor 301.

[0019] Preferably, the main body of the pre-reactor 301 is a cuboid, and the left and right sides are arc surfaces. The liquid inlet B (311) and the liquid outlet B (314) are on the arc surfaces. The length of the cuboid is more than 3 times the width. The pre-reactor 301 is relatively long and narrow along the flowing direction of the working liquid. The working liquid enters from one side of the upper part of the pre-reactor 301 and leaves from the other side of the lower part, while the gas enters from the bottom of the pre-reactor 301, is distributed by a gas distributor at the bottom and then contacts the working liquid in a countercurrent manner to react, and then leaves from the top.

[0020] The present invention has the following beneficial effects:

[0021] (1) By adding an arcuate tray with multiple holes in the oxidation tower, in the case of upward co-current flow of gas-liquid two-phase, the liquid main body and the gas flow in a cross-flow manner between the arcuate trays, which can increase the contact of the gas-liquid two-phase, is beneficial to mass transfer and reaction, and is beneficial to improving the oxidation yield and reducing the tail oxygen content; in addition, the present invention changes the traditional co-current oxidation tower from two towers or three towers in series to a single tower, which is beneficial to reducing the equipment size;

[0022] (2) In the present invention, a pre-reactor and a post-reactor are additionally added before and after the original oxidation tower; in the post-reactor, the gas is in a micro-bubble state, and the contact area between the gas and liquid phases is large, which is conducive to further improving the oxidation yield, reducing the tail oxygen content, and enhancing the safety of the oxidation system in the process of preparing hydrogen peroxide by the anthraquinone method. The setting of the pre-reactor can significantly reduce the tail oxygen content, thereby improving the economic benefits of the entire device. Description of the Drawings

[0023] Figure 1 is a schematic diagram of the oxidation device for producing hydrogen peroxide according to the present invention;

[0024] Figure 2 is a schematic diagram of the oxidation device with a post-reactor for producing hydrogen peroxide according to the present invention;

[0025] Figure 3 is a schematic diagram of the oxidation device with a pre-reactor and a post-reactor for producing hydrogen peroxide according to the present invention;

[0026] Figure 4 is the bow-shaped tray with circular holes according to the present invention;

[0027] Figure 5 is the bow-shaped tray with tongue-shaped holes according to the present invention;

[0028] In the figure: 101, oxidation tower; 102, bow-shaped tray; 103, gas-liquid separator; 104, gas distributor; 201, micro-bubble generator; 202, post-reactor; 301, pre-reactor; 111, gas inlet A; 112, liquid inlet A; 113, gas outlet A; 114, liquid outlet A; 311, liquid inlet B; 312, gas outlet B; 313, gas inlet B; 314, liquid outlet B; 1021, chord of the bow-shaped tray. Detailed Embodiments

[0029] The present invention will be further described below with reference to the accompanying drawings through specific embodiments. The following embodiments are only descriptive and cannot be used to limit the protection scope of the present invention.

[0030] Figure 1 In [embodiment], the gas enters from the gas inlet A 111, is distributed by the gas distributor 104 and then enters the oxidation tower 101. The liquid enters the oxidation tower 101 from the liquid inlet A 112. The gas and the liquid flow upward in parallel macroscopically and react in the oxidation tower 101. The reaction temperature is 40 - 65 °C, and the reaction pressure is 0.18 - 0.6 MPa. After passing through the gas-liquid separator 103, they flow out of the oxidation tower 101 from the gas outlet A 113 and the liquid outlet A 114 respectively.

[0031] Figure 2In this process, the oxidized liquid flowing out from the liquid outlet A 114 is mixed with a part of fresh air through the microbubble generator 201 to form a microbubble flow, which enters the post-reactor 202 for further reaction. The amount of the part of fresh air does not exceed 50% of the total air volume of the oxidation tower 101. The oxidized liquid after further reaction enters the heat exchanger or the next process, and the air that reacts in the post-reactor 202 is mixed with the air to be introduced into the oxidation tower 101 and then enters the oxidation tower 101.

[0032] Figure 3 In this process, before the working liquid enters the oxidation tower 101, it first enters the pre-reactor 301. 10 - 100% of the air part coming out from the gas outlet A at the top of the oxidation tower 101 enters the bottom of the pre-reactor 301. After being distributed by the gas distributor, it contacts the working liquid countercurrently for reaction. The reacted air enters the oxidation tail gas condenser, and the reacted working liquid enters the oxidation tower 101.

[0033] Example 1

[0034] The oxidation device designed according to the present invention, as Figure 1 shown, includes an oxidation tower 101, an arc-shaped tray 102, a gas distributor 104, and a gas-liquid separator 103. Among them, the gas inlet A 111 and the liquid inlet A 112 are on both sides of the lower part of the oxidation tower 101. After air and the hydrogenated liquid coming out from the hydrogenation tower enter the oxidation tower 101 from the gas inlet A 111 and the liquid inlet A 112 respectively, they macroscopically flow upward in parallel and react in the oxidation tower. After gas-liquid separation, they flow out of the oxidation tower 101 from the gas outlet A113 and the liquid outlet A114 respectively; the chord length of the arc-shaped tray accounts for 20% of the diameter of the oxidation tower 101, and adjacent arc-shaped trays are alternately distributed in an S shape, and the distance between adjacent arc-shaped trays is 200 cm; circular holes are evenly distributed on the arc-shaped tray, the size of the holes is 5 mm, and the hole opening ratio is 5%; the flow rate of the working liquid is 930 m 3 / h, the oxidation reaction temperature is 50 °C, the air inlet pressure is 0.4 MPa, the apparent residence time of the working liquid is 30 min, and when the air flow rate is 30995 Nm 3 / h, the oxidation yield is 96.0%, and the tail oxygen content is 5.8%.

[0035] Example 2

[0036] Other design and operation steps are the same as those in Example 1. The difference is that when the air flow rate is 29110 Nm 3 / h, the obtained results are that the oxidation yield is 95.6% and the tail oxygen content is 4.7%.

[0037] Example 3

[0038] Other design and operation steps are the same as those in Example 1, except that the chord length of the segmental tray 102 accounts for 90% of the tower diameter; the distance between adjacent segmental trays is 30 cm; when the air flow rate is 28877 Nm 3 / h, the oxidation yield is 95.8% and the tail oxygen content is 4.5%.

[0039] Example 4

[0040] Other design and operation steps are the same as those in Example 1, except that the chord length of the segmental tray 102 accounts for 50% of the tower diameter; the distance between adjacent segmental trays is 80 cm; when the air flow rate is 28682 Nm 3 / h, the oxidation yield is 96.1% and the tail oxygen content is 4.3%.

[0041] Example 5

[0042] Other design and operation steps are the same as those in Example 4, except that there is another post-reactor 202 after the working fluid exits the oxidation tower 101. The oxidized liquid from the gas-liquid separator 103 of the oxidation tower 101 is mixed with a part of fresh air through the microbubble generator 201 to form a microbubble flow and enters the post-reactor 202 for further reaction. The part of fresh air is 30% of the total air volume entering the oxidation tower 101. The oxidized liquid after further reaction enters the heat exchanger, and the air reacting in the post-reactor 202 is mixed with the air to be entered into the oxidation tower 101 and then enters the oxidation tower 101; when the air flow rate is 29310 Nm 3 / h, the oxidation yield is 98.2% and the tail oxygen content is 4.3%.

[0043] Example 6

[0044] Other design and operation steps are the same as those in Example 4, except that there is another post-reactor 202 after the working fluid exits the oxidation tower 101. The oxidized liquid from the gas-liquid separator 103 of the oxidation tower 101 is mixed with a part of fresh air through the microbubble generator 201 to form a microbubble flow and enters the post-reactor 202 for further reaction. The part of fresh air is 15% of the total air volume entering the oxidation tower. The oxidized liquid after further reaction enters the heat exchanger, and the air reacting in the post-reactor 202 is mixed with the air to be entered into the oxidation tower 101 and then enters the oxidation tower 101; when the air flow rate is 29310 Nm 3 / h, the oxidation yield is 97.3% and the tail oxygen content is 4.5%.

[0045] Example 7

[0046] Other design and operation steps are the same as those in Example 4. The difference is that there is another post-reactor 202 after the working fluid exits the oxidation tower 101. The oxidized liquid coming out of the gas-liquid separator 103 of the oxidation tower 101 is mixed with a part of fresh air through a microbubble generator 201 to form a microbubble stream and enters the post-reactor 202 for further reaction. The part of fresh air is 50% of the total air volume entering the oxidation tower. The oxidized liquid after further reaction enters the heat exchanger, and the air that reacts in the post-reactor 202 is mixed with the air to be entered into the oxidation tower 101 and then enters the oxidation tower 101; the air flow rate is 29310 Nm 3 / h, the oxidation yield is 98.3%, and the tail oxygen content is 4.3%.

[0047] Example 8

[0048] Other design and operation steps are the same as those in Example 5. The difference is that the working fluid enters a pre-reactor 301 before entering the oxidation tower 101. 50% of the air coming out of the oxidation tower 101 enters the bottom of the pre-reactor 301, and after being distributed by the gas distributor, it reacts with the working fluid. The reacted air enters the oxidation tail gas condenser; the air flow rate is 26510 Nm 3 / h, the oxidation yield is 98.2%, and the tail oxygen content is 2.1%.

[0049] Comparative Example 1

[0050] A conventional tandem oxidation tower consisting of upper and lower towers is selected. Each of the upper and lower towers has a gas-liquid separator at the top. The hydrogenated liquid enters from the lower part of the upper tower. After the gas and liquid flow upward in parallel for reaction, it enters the lower part of the lower tower after being separated by the gas-liquid separator in the upper tower. After the gas and liquid flow upward in parallel again for reaction, it leaves from the upper part of the lower tower after gas-liquid separation and enters the extraction section; air enters from the lower part of the lower tower, enters the lower part of the upper tower after gas-liquid separation from the upper part of the lower tower, and enters the tail gas treatment section after gas-liquid separation from the upper part of the upper tower; the working fluid flow rate is 930 m 3 / h, the oxidation reaction temperature is 50 °C, the air inlet pressure is 0.4 MPa, the apparent residence time of the working fluid is 30 min, and the air flow rate is 30995 Nm 3 / h, the oxidation yield is 94.0%, and the tail oxygen content is 6.2%.

[0051] Comparative Example 2

[0052] There is no segmental baffle in the oxidation tower 101, and the rest is exactly the same as in Example 1. The working fluid flow rate is 930 m 3 / h, the oxidation reaction temperature is 50 °C, the air inlet pressure is 0.4 MPa, the apparent residence time of the working fluid is 30 min, and the air flow rate is 30995 Nm 3 / h, the oxidation yield is 84.1% and the tail oxygen content is 8.0%.

[0053] Comparative Example 3

[0054] Other design and operation steps are the same as those in Example 4. The difference is that there is another post-reactor 202 after the working fluid exits the oxidation tower 101. The oxidized liquid from the gas-liquid separator 103 of the oxidation tower 101 is mixed with a part of fresh air through a microbubble generator 201 to form a microbubble flow and enters the post-reactor 202 for further reaction. The part of fresh air is 60% of the total air volume entering the oxidation tower. The oxidized liquid after further reaction enters the heat exchanger, and the air reacting in the post-reactor 202 is mixed with the air to be entered into the oxidation tower 101 and then enters the oxidation tower 101; the air flow rate is 29310 Nm 3 / h, the oxidation yield is 97.7% and the tail oxygen content is 4.4%.

Claims

1. An oxidation device for producing hydrogen peroxide, comprising an oxidation tower (101), characterized in that, On both sides of the lower part of the oxidation tower (101), a gas inlet A (111) and a liquid inlet A (112) are respectively arranged. A gas outlet A (113) is arranged at the top, and a liquid outlet A (114) is arranged on the upper side surface. A gas-liquid separator (103), a gas distributor (104), and segmental trays (102) are arranged inside the oxidation tower (101). The liquid inlet A (112) is located below the gas distributor (104). The segmental trays (102) are provided with uniformly distributed holes, and adjacent segmental trays (102) are alternately distributed; The oxidation device is provided with a microbubble generator (201) and a post-reactor (202). The oxidation liquid flowing out from the liquid outlet A (114) of the oxidation tower (101) and part of the fresh air are mixed by the microbubble generator (201) to form a microbubble flow and enter the post-reactor (202). The gas coming out from the top of the post-reactor (202) is mixed with the fresh air and then enters the oxidation tower (101).

2. The oxidation device according to claim 1, characterized in that, The distance between the first segmental tray (102) above the gas distributor (104) and the gas distributor (104) is 1 - 5 m, and the distance between adjacent segmental trays (102) is 30 cm - 200 cm.

3. The oxidation device according to claim 2, characterized in that, The chord (1021) length of the segmental tray (102) accounts for 20% - 90% of the tower body diameter, and the area of the segmental tray (102) accounts for more than half of the cross-sectional area of the oxidation tower (101).

4. The oxidation device according to claim 1, characterized in that, The shape of the holes on the segmental tray (102) is circular or tongue-shaped. The size of the circular holes is 1 mm - 30 mm, and the hole opening rate is 0.1% - 10%; the hole opening rate of the tongue-shaped holes is 0.1% - 10%.

5. The oxidation device according to claim 1, characterized in that, The gas inlets of the oxidation tower (101) are 1 - 10, and are arranged successively from the bottom to the top on the side surface of the oxidation tower (101).

6. The oxidation device according to claim 5, characterized in that, There are 3 gas inlets, which are respectively located at the bottom of the side surface of the oxidation tower (101), at the 1 / 2 height position of the side surface of the oxidation tower (101), and at the 3 / 4 height position.

7. The oxidation device according to claim 1, characterized in that, The gas distributor (104) is a gas distributor with circular holes. The size of the holes of the gas distributor (104) is 20 μm - 1000 μm, and the perforation flow rate is 0.1 m / s - 10 m / s.

8. The oxidation device according to claim 7, characterized in that, The size of the holes of the gas distributor (104) is 20 - 100 μm.

9. The oxidation device according to claim 1, characterized in that, The gas distributor (104) is a gas distributor with a microporous structure. The microporous structure includes a metal sintered microporous tube, a ceramic sintered microporous tube, a microporous membrane, a microporous membrane tube, or a microchannel with a pore diameter of 0.01 - 50 μm. The gas distributor (104) enters the oxidation tower (101) in the form of microbubbles through the microporous structure.

10. The oxidation device according to claim 1, characterized in that, The amount of fresh air entering the microbubble generator (201) does not exceed 50% of the total air amount of the main body of the oxidation tower (101).

11. The oxidation device according to claim 10, characterized in that, The amount of fresh air entering the microbubble generator (201) does not exceed 10% - 30% of the total air amount of the main body of the oxidation tower (101).

12. The oxidation device according to claim 1, characterized in that, The microbubble generator (201) is made of a Venturi injector, a sintered metal microporous tube, a sintered ceramic microporous tube, a microporous plate or a microporous membrane, or forms a microbubble flow by the pressurized dissolved air releasing method or the tangential swirl method.

13. The oxidation device according to claim 1, characterized in that, The oxidation device is provided with a pre-reactor (301). The upper part of the side of the pre-reactor (301) is provided with a liquid inlet B (311), the top is provided with a gas outlet B (312), the bottom is provided with a gas inlet B (313), and the lower part of the side is provided with a liquid outlet B (314). The gas coming out of the oxidation tower (101) enters from the bottom of the pre-reactor (301) and reacts with the working fluid, and the reacted gas enters the oxidation tail gas condenser.

14. The oxidation device according to claim 13, characterized in that, 10-100% of the gas coming out of the oxidation tower (101) enters the pre-reactor (301).

15. The oxidation device according to claim 13, characterized in that, The main body of the pre-reactor (301) is a cuboid, and the left and right sides are arc surfaces. The liquid inlet B (311) and the liquid outlet B (314) are on the arc surfaces, and the length of the cuboid is more than 3 times the width.

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