An oxidation device for producing hydrogen peroxide

Abstract

The present invention discloses an oxidation device for producing hydrogen peroxide, which comprises an oxidation tower, a microbubble generator and a post-reactor. A liquid inlet A is arranged on the upper side of the oxidation tower, a liquid outlet A, a gas inlet A are arranged at the lower part, and a gas outlet A is arranged at the top. An arc-shaped tray, a liquid distributor, a gas distributor and a gas-liquid separator are arranged inside the oxidation tower. The liquid outlet A is located below the gas distributor. The arc-shaped trays are provided with evenly distributed holes, and adjacent arc-shaped trays are alternately distributed. The oxidation liquid flowing out from the liquid outlet A of the oxidation tower and fresh air are mixed through the microbubble generator to form a microbubble flow and enter the post-reactor. The gas coming out from the top of the post-reactor is mixed with fresh air and then enters the oxidation tower. The oxidation device of the present invention can improve the conversion rate of the reaction, reduce the volume of the reactor, increase the oxidation yield, reduce the content of tail oxygen, and improve the safety performance.

Description

Technical Field

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

[0002] Currently, 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 appropriate solvents for dissolving anthraquinone and anthrahydroquinone and substances for adjusting the pH of the solution are selected to jointly form a working solution. The entire 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. C9 aromatic hydrocarbons are mostly used in China, which is a mixture containing mesitylene, methyl ethyl benzene, etc., while C10 aromatic hydrocarbons are mostly used abroad. 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 series connection of two towers or three towers. In the tower, in addition to 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%. Currently, there are disadvantages in the industry such as low oxidation yield and high tail oxygen content. Compared with co-current flow, countercurrent contact of gas-liquid two-phase has the advantage of high mass transfer rate. Summary of the Invention

[0004] The object of the present invention is to provide an oxidation device for producing hydrogen peroxide. The hydrogenated liquid of the device enters from the upper part of the oxidation tower through a liquid distributor and flows downward, while air enters the oxidation tower from the lower part through a gas distributor and flows upward. Macroscopically, the gas-liquid two-phase shows countercurrent contact. In addition, due to the influence of the segmental trays, the liquid flows in an S-shaped cross-flow in 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. At the bottom of the oxidation tower, the air enters the oxidation tower in the form of microbubbles after passing through a gas distributor with a microporous structure and contacts the hydrogenated liquid with a lower reactant concentration, which is beneficial to improving the conversion rate of the reaction and reducing the volume of the oxidation tower. In addition, the air at the outlet of the oxidation tower can further reduce the tail oxygen content after passing through a pre-reactor, and the working liquid at the outlet of the oxidation tower can further improve the conversion rate of the hydrogenated liquid and the yield of hydrogen peroxide after passing through a post-reactor, thereby improving the economic benefits of the entire device.

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

[0006] An oxidation device for producing hydrogen peroxide, characterized in that it includes an oxidation tower 101, a microbubble generator 201 and a post-reactor 202. A liquid inlet A 111 is provided on the side of the upper part of the oxidation tower 101, a liquid outlet A 112, a gas inlet A 113 are provided on the lower part, and a gas outlet A 114 is provided on the top. A segmental tray 102, a liquid distributor 103, a gas distributor 104 and a gas-liquid separator 105 are arranged in the oxidation tower 101. The liquid outlet A 112 is located below the gas distributor 104. The segmental tray 102 is provided with uniformly distributed holes, and adjacent segmental trays 102 are alternately distributed. The oxidized liquid flowing out from the liquid outlet A (112) 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).

[0007] Preferably, the amount of fresh air entering the microbubble generator (201) does not exceed 50% of the total air volume of the oxidation tower main body (101), and is preferably 10-30%.

[0008] Preferably, 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, etc., or forms a microbubble flow by the pressurized dissolved gas releasing method or the tangential swirl method.

[0009] The gas distributor 104 is a gas distributor with a microporous structure, and the microporous structure is preferably 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 allows gas to enter the oxidation tower 101 in the form of microbubbles through the microporous structure.

[0010] The first segmental baffle plate 102 above the gas distributor 104 is 2 - 10 m away from the gas distributor 104, and the spacing between adjacent segmental baffle plates 102 is 50 cm - 200 cm; preferably, the first segmental baffle plate 102 above the gas distributor 104 is 3 - 5 m away from the gas distributor 104, and the spacing between adjacent segmental baffle plates 102 is 80 cm - 150 cm.

[0011] Preferably, the chord length of the segmental baffle plate (102) accounts for 20% - 90% of the tower body diameter, and the area of the segmental baffle plate (102) accounts for more than half of the cross-sectional area of the oxidation tower (101).

[0012] Preferably, the shape of the holes on the segmental baffle plate (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%.

[0013] Preferably, 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 B311, the top is provided with a gas outlet B314, the bottom is provided with a gas inlet B313, and the lower part of the side is provided with a liquid outlet B312. 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; preferably, 10% - 100% of the gas coming out of the oxidation tower 101 enters the pre-reactor 301;

[0014] Preferably, the main body of the pre-reactor 301 is a cuboid, and the left and right sides are arc surfaces. The liquid inlet B311 and the liquid outlet B312 are on the arc surfaces, and the length of the cuboid is more than 3 times the width.

[0015] The present invention has the following beneficial effects:

[0016] (1) The present invention adopts the countercurrent contact mode of gas-liquid two-phase for the oxidation reaction of anthraquinone. Between the segmental trays, the liquid main body and the gas flow in a cross-flow manner. The presence of segmental trays in the oxidation tower will further divide the gas phase into smaller bubbles. Compared with the traditional co-current contact of gas-liquid two-phase, the mass transfer driving force is high, the mass transfer rate is fast, which is beneficial to improving the oxidation yield and reducing the content of tail oxygen. In addition, the gas at the bottom of the oxidation tower enters the oxidation tower in the form of micro-bubbles through the gas distributor with a microporous structure, which can significantly increase the contact area of gas-liquid two-phase and improve the conversion rate of anthraquinone.

[0017] (2) The present invention additionally adds a pre-reactor and a post-reactor before and after the original oxidation tower. In the post-reactor, the gas is in a micro-bubble state, and the contact area of gas-liquid two-phase is large, which is beneficial to further improving the oxidation yield and reducing the content of tail oxygen, and improving 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 content of tail oxygen, thereby improving the economic benefits of the whole device. Brief Description of the Drawings

[0018] Figure 1 is a schematic diagram of the oxidation device containing a post-reactor for producing hydrogen peroxide according to the present invention;

[0019] Figure 2 is a schematic diagram of the countercurrent oxidation device containing a pre-reactor and a post-reactor for producing hydrogen peroxide according to the present invention;

[0020] Figure 3 is the segmental tray with circular holes according to the present invention;

[0021] Figure 4 is the segmental tray with split valve holes according to the present invention;

[0022] In the figure: 101, oxidation tower; 102, segmental tray; 103, liquid distributor; 104, gas distributor; 105, gas-liquid separator; 201, micro-bubble generator; 202, post-reactor; 301, pre-reactor; 111, liquid inlet A; 112, liquid outlet A; 113, gas inlet A; 114, gas outlet A; 311, liquid inlet B; 312, liquid outlet B; 313, gas inlet B; 314, gas outlet B; 1021, chord of the segmental tray. Detailed Embodiments

[0023] 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.

[0024] Figure 1In it, gas enters from gas inlet A 113, is distributed by gas distributor 104 and then enters oxidation tower 101 and flows upward. Liquid enters from liquid inlet A 111, is distributed by liquid distributor 103 and then enters oxidation tower 101 and flows downward. Macroscopically, the gas-liquid two-phase shows countercurrent contact and reacts in oxidation tower 101. The reaction temperature is 40 - 65 °C and the reaction pressure is 0.10 - 1.0 MPa. Then the gas passes through gas-liquid separator 105 and leaves oxidation tower 101 from gas outlet A 114 at the top of the oxidation tower; the liquid leaves oxidation tower 101 through liquid outlet A112 at the bottom of oxidation tower 101, forms a microbubble flow after being mixed with part of the fresh air through microbubble generator 201 and enters post-reactor 202 for further reaction. The part of the fresh air does not exceed 50% of the total air volume of oxidation tower 101. The oxidized liquid after further reaction enters a heat exchanger or enters the next process, and the air that reacts in post-reactor 202 is mixed with the air to be entered into oxidation tower 101 and then enters oxidation tower 101.

[0025] Figure 2 In it, before the working liquid enters oxidation tower 101, it first enters pre-reactor 301. 10 - 100% of the part of the air coming out from gas outlet A at the top of oxidation tower 101 enters the bottom of pre-reactor 301, is distributed by the gas distributor and then contacts the working liquid countercurrently to react. The reacted air enters the oxidation tail gas condenser, and the reacted working liquid enters oxidation tower 101.

[0026] Example 1

[0027] The oxidation device designed according to the present invention, as Figure 1As shown in the figure, it includes an oxidation tower 101, an arc-shaped tray 102, a liquid distributor 103, a gas distributor 104, and a gas-liquid separator 105. The liquid inlet A111 is located at the upper part of the oxidation tower 101, the liquid outlet A112 is at the lower part of the oxidation tower 101, the gas inlet A113 is at the lower part of the oxidation tower 101, and the gas outlet A114 is at the top of the oxidation tower 101. The gas enters from the gas inlet A113, is distributed by the gas distributor 104 and then enters the oxidation tower 101 and flows upward. The liquid enters from the liquid inlet A111, is distributed by the liquid distributor 103 and then enters the oxidation tower 101 and flows downward. Macroscopically, the gas-liquid two-phase shows countercurrent contact and reacts in the oxidation tower 101. Then the liquid leaves the oxidation tower 101 through the liquid outlet 112 at the bottom of the oxidation tower 101, and the gas leaves the oxidation tower 101 from the gas outlet A114 at the top of the oxidation tower 101 after passing through the gas-liquid separator 105; there are multiple holes with a diameter of 1 mm on the gas distributor 104, and the hole opening rate is 3%; 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 rate is 5%; after the working liquid leaves the oxidation tower 101, there is another post-reactor 202. The liquid leaves the oxidation tower 101 through the liquid outlet A112 at the bottom 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 50% of the total air volume entering the oxidation tower 101. The oxidized liquid after further reaction enters the next process, 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 working liquid flow rate is 930m 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 28 min, and when the air flow rate is 30930 Nm 3 / h, the oxidation yield is 98.1% and the tail oxygen content is 5.4%.

[0028] Example 2

[0029] Other design and operation steps are the same as those in Example 1. The difference is that when the air flow rate is 27360 Nm 3 / h, the obtained results are that the oxidation yield is 97.7% and the tail oxygen content is 3.0%.

[0030] Example 3

[0031] Other design and operation steps are the same as those in Example 1. The difference is that the liquid leaves the oxidation tower 101 through the liquid outlet A112 at the bottom of the oxidation tower 101, and forms a microbubble flow after mixing with a part of fresh air through the microbubble generator 201 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; when the air flow rate is 30930 Nm 3 / h, the obtained results are that the oxidation yield is 98.0% and the tail oxygen content is 5.4%.

[0032] Example 4

[0033] Other design and operation steps are the same as those in Example 1. The difference is that the liquid leaves the oxidation tower 101 through the liquid outlet A112 at the bottom of the oxidation tower 101, and forms a microbubble flow after mixing with a part of fresh air through the microbubble generator 201 and enters the post-reactor 202 for further reaction. The part of fresh air is 10% of the total air volume entering the oxidation tower 101; when the air flow rate is 30930 Nm 3 / h, the obtained results are that the oxidation yield is 97.5% and the tail oxygen content is 5.5%.

[0034] Example 5

[0035] Other design and operation steps are the same as those in Example 1. The difference is that the gas distributor 104 is a sintered metal microporous tube with a pore diameter of 0.1 μm, and the distance between the first segmental tray 102 above the gas distributor 104 and the gas distributor 104 is 5 m; the apparent residence time of the working liquid is 28 min, and the air flow rate is 30930 Nm 3 / h, the oxidation yield is 98.8% and the tail oxygen content is 5.2%.

[0036] Example 6

[0037] Other design and operation steps are the same as those in Example 3. The difference is that when the air flow rate is 27220 Nm 3 / h, the obtained results are that the oxidation yield is 98.3% and the tail oxygen content is 2.7%.

[0038] Example 7

[0039] Other design and operation steps are the same as those in Example 3. The difference is 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; the air flow rate is 27220 Nm 3 / h, the oxidation yield is 98.4% and the tail oxygen content is 2.7%.

[0040] Example 8

[0041] Other design and operation steps are the same as those in Example 3, except that the chord length of the bow-shaped tray 102 accounts for 50% of the tower diameter; the distance between adjacent bow-shaped trays is 80 cm; when the air flow rate is 27220 Nm 3 / h, the oxidation yield is 99.0% and the tail oxygen content is 2.5%.

[0042] Example 9

[0043] Other design and operation steps are the same as those in Example 8, except 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; when the air flow rate is 26010 Nm 3 / h, the oxidation yield is 99.1% and the tail oxygen content is 1.5%.

[0044] Comparative Example 1

[0045] A conventional two-tower series oxidation tower is selected, including an upper tower and a lower tower, and there is a gas-liquid separator at the top of each of the upper and lower towers. The hydrogenated liquid enters from the lower part of the upper tower. After the gas and liquid flow upward in parallel and react, they enter 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 and react again, they leave from the upper part of the lower tower after gas-liquid separation and enter 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 28 min, and the air flow rate is 30930 Nm 3 / h, the oxidation yield is 92.1% and the tail oxygen content is 6.5%.

[0046] Comparative Example 2

[0047] Others are the same as in Example 1, except that there is no microbubble generator 201 and post-reactor 202; 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 28 min, and the air flow rate is 30930 Nm 3 / h, the oxidation yield is 96.2% and the tail oxygen content is 5.7%.

[0048] Comparative Example 3

[0049] Other design and operation steps are the same as those in Example 1. The difference is that the liquid leaves the oxidation tower 101 through the liquid outlet A112 at the bottom of the oxidation tower 101, and forms a microbubble flow after being mixed with a part of fresh air through the microbubble generator 201 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 101; when the air flow rate is 30930 Nm 3 / h, the obtained results are that the oxidation yield is 97.6% and the tail oxygen content is 5.4%.

Claims

1. An oxidation device for producing hydrogen peroxide, characterized in that, It includes an oxidation tower (101), a microbubble generator (201) and a post-reactor (202). On the upper side of the oxidation tower (101), there is a liquid inlet A (111). At the lower part, there are a liquid outlet A (112) and a gas inlet A (113), and at the top, there is a gas outlet A (114). Inside the oxidation tower (101), there are segmental trays (102), a liquid distributor (103), a gas distributor (104), and a gas-liquid separator (105). The liquid outlet 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. The oxidized liquid flowing out from the liquid outlet A (112) 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 amount of fresh air entering the microbubble generator (201) does not exceed 50% of the total air volume of the oxidation tower (101).

3. The oxidation device according to claim 2, characterized in that, The amount of fresh air entering the microbubble generator (201) does not exceed 10 - 30% of the total air volume of the oxidation tower (101).

4. The oxidation device according to claim 1 or 2, 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.

5. The oxidation device according to claim 1, characterized in that, The gas distributor (104) is a gas distributor with a microporous structure.

6. The oxidation device according to claim 5, characterized in that, The gas distributor with a microporous structure is a sintered metal microporous tube, a sintered ceramic 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) makes the gas enter the oxidation tower (101) in the form of microbubbles through the microporous structure.

7. The oxidation device according to claim 1 or 5, characterized in that, The distance between the first segmental tray (102) above the gas distributor (104) and the gas distributor (104) is 2 - 10 m, and the distance between adjacent segmental trays (102) is 50 cm - 200 cm.

8. The oxidation device according to claim 7, characterized in that, The distance between the first segmental tray (102) above the gas distributor (104) and the gas distributor (104) is 3 - 5 m, and the distance between adjacent segmental trays (102) is 80 cm - 150 cm.

9. The oxidation device according to claim 1 or 5, characterized in that, The chord length of the segmental tray (102) accounts for 20% - 90% of the tower diameter, and the area of the segmental tray (102) accounts for more than half of the cross-sectional area of the oxidation tower (101).

10. The oxidation device according to claim 1 or 5, 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%.

11. The oxidation device according to claim 1 or 5, 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 (314), the bottom is provided with a gas inlet B (313), and the lower part of the side is provided with a liquid outlet B (312). 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.

12. The oxidation device according to claim 11, characterized in that, 10 - 100% of the gas coming out of the oxidation tower (101) enters the pre-reactor (301).

13. The oxidation device according to claim 11, 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 (312) are on the arc surfaces, and the length of the cuboid is more than 3 times the width.

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