CN101244996A - A vertical bubbling oxidation reaction device for synthesizing naphthalene dicarboxylic acid - Google Patents

Abstract

A vertical bubbling oxidation reaction device for synthesizing naphthalene dicarboxylic acid, mainly composed of a straight cylinder (1), a top cover (2), a bottom cover (3), a liquid distributor (4), a structured packing (5), a reaction Liquid (6), gas distributor (7), feed inlet (8) and outlet (9), the reaction device is mainly a vertical cylindrical structure, the top is equipped with a liquid distributor (4), structured packing (5) The reaction solution (6) is contained inside, and the bottom is provided with a gas distributor (7) consisting of (4-8) spray pipes (71) uniformly distributed from the center of the bottom end. According to the needs of the oxidation reaction, a rectifying section (11), a free section (12) and a reaction section (13) are arranged in the device, and a feed port (8) and a feed port (9) are also provided on the side thereof. The invention has the advantages of simple structure, convenient operation, reliable operation, no stirring device, low cost, and easy maintenance and repair.

Description

A vertical bubbling oxidation reaction device for synthesizing naphthalene dicarboxylic acid

technical field

The invention relates to a chemical reaction synthesis equipment, in particular to a vertical bubbling oxidation reaction device for preparing 2,6-naphthalene dicarboxylic acid oxidation product by oxidizing dialkylnaphthalene in liquid phase with oxygen-containing gas.

Background technique

At present, the production process of preparing 2,6-naphthalene dicarboxylic acid by oxidation of 2,6-dialkylnaphthalene in foreign countries is similar to the production process of terephthalic acid by oxidation of p-xylene, and both adopt continuous stirring bubble reactor to realize 2 , The liquid-phase oxidation reaction of 6-dialkylnaphthalene has not yet been reported on industrial production in China. A stirred high-pressure reactor is selected as the reactor for the liquid-phase oxidation of 2,6-dialkylnaphthalene because it is conducive to heat transfer and accelerated mass transfer between the gas-liquid two-phase, and is easy to operate. However, the disadvantages of this reactor are also obvious, mainly in two points: one is that the equipment is complex, the maintenance cost is high, especially there is a sealing problem for high temperature and high pressure conditions; the other is that the energy consumption required for stirring is relatively high. Aiming at the deficiency of the stirred reactor, it is very necessary to develop a new bubbling oxidation reaction device for the synthesis of naphthalene dicarboxylic acid.

Contents of the invention

According to the background technology, the object of the present invention is to provide a high-efficiency and energy-saving reaction device for the synthesis of naphthalene dicarboxylic acid. The bottom is equipped with a gas distributor that is very important for the oxidation reaction, so that the oxygen-containing gas passes through the reaction area in a countercurrent manner, and a vertical bubbling oxidation reaction device with a feed inlet and a discharge outlet is installed on one side of the equipment.

In order to achieve the above object, the present invention is achieved through the following technical solutions:

A vertical bubbling oxidation reaction device for synthesizing naphthalene dicarboxylic acid, mainly composed of a straight cylinder (1), a top cover (2), a bottom cover (3), a liquid distributor (4), a structured packing (5), a reaction Liquid (6), gas distributor (7), feed inlet (8) and discharge outlet (9), wherein: straight cylinder body (1) is a straight cylinder structure, its length is L, inner wall diameter is D, straight cylinder The length L of body (1) should comprise the length of rectifying section (11) that oxidation reaction needs, the length of free section (12) and the length H of reaction section (13), the length H of its reaction section (13) should be (60～90)% of the length L of the straight cylinder (1), preferably (70～80)%, and H/D=2～8; the free section between the rectifying section (11) and the reaction section (13) The length of (12) should be (10～20)% of straight cylinder body (1) length L; Rectifying section (11) is arranged in the position with specific surface area α=400～1500, porosity ε=0.90～0.98, The internal member of structured packing with specific surface area α = 600-1200 and porosity ε = 0.92-0.96 is preferred; the volume of the reaction solution (6) filled in the straight cylinder (1) should be (40-50) of the volume of the straight cylinder (1). )%; the top of the straight cylinder (1) is provided with a liquid distributor (4), a top cover (2) is installed on it, a bottom cover (3) is installed at the bottom, and a A gas distributor (7) composed of (4-8) nozzle pipes (71) evenly distributed from the center of the bottom end, whose total cross-sectional area is (0.5-5)% of the cross-sectional area of the straight cylinder (1), preferably (1～3)%, every nozzle (71) outlet gas velocity is (3～15) m/s, preferably (6～10) m/s; /3) There is a material inlet (8) at L, and a material outlet (9) at the bottom of the straight cylinder (1); the overall structure of the straight cylinder (1) should be able to withstand the temperature of (170-240) ° C, And (0.8 ~ 4) Mpa pressure.

Owing to adopting above-mentioned technical scheme, the present invention has following advantage and effect:

1. The present invention effectively controls the oxidation reaction toward the target product, and fully reduces the content of by-products, improves the yield and purity of the target product, and reduces production costs.

2. The present invention does not use a stirring device, has simple structure, reliable operation, low cost, and is easy to use, maintain and repair.

Description of drawings

Fig. 1 is the overall sectional schematic diagram of structure of the present invention

Fig. 2 is the schematic diagram of the first embodiment of the nozzle arrangement of the gas distributor of the present invention

Fig. 3 is the schematic diagram of the second embodiment of the nozzle arrangement of the gas distributor of the present invention

Fig. 4 realizes 2,6-dialkylnaphthalene oxidation flowchart for the present invention

Detailed ways

Shown in Fig. 1, a kind of vertical bubbling oxidation reaction device used for synthesizing naphthalene dicarboxylic acid mainly consists of a straight cylinder 1, a top cover 2, a bottom cover 3, a liquid distributor 4, a structured packing 5, a reaction solution 6, a gas Distributor 7, feed inlet 8 and discharge outlet 9, wherein: straight cylinder 1 is a straight cylinder structure with a length of L and an inner wall diameter of D, and the length L of the straight cylinder 1 should include the rectification section required for the oxidation reaction The length of 11, the length of free section 12 and the length H of reaction section 13, the length H of its reaction section 13 should be (60～90)% of straight cylinder 1 length L, preferably (70～80)%, and H /D=2～8; The length of the free section 12 between the rectifying section 11 and the reaction section 13 should be (10～20)% of the length L of the straight cylinder body 1; α=400～1500, porosity ε=0.90～0.98, preferably specific surface area α=600～1200 and porosity ε=0.92～0.96 internal member of structured packing; the volume of the reaction solution 6 filled in the straight cylinder body 1 should be a straight cylinder (40-50)% of the volume of the body 1; the top of the straight cylinder 1 is provided with a liquid distributor 4, a top cover 2 is installed on it, a bottom cover 3 is installed at the bottom, and a The gas distributor 7 that evenly distributes 4～8 nozzle pipes 71 from the center of the bottom end is formed, and its total cross-sectional area is (0.5～5)% of the cross-sectional area of the straight cylinder body 1, preferably (1～3)%. Root nozzle 71 outlet gas velocity is (3～15) m/s, preferred (6～10) m/s; The (1/2～2/3) L place of straight cylinder body 1 is provided with feeding port 8, A discharge port 9 is arranged at the bottom of the straight cylinder 1; the overall structure of the straight cylinder 1 should be able to withstand a high temperature of (170-240) °C and a pressure of (0.8-4) Mpa.

It is also known that the 2,6-dialkylnaphthalene and its oxidation products in the liquid phase reaction zone of the present invention pass through the reaction device continuously in the form of fully mixed flow, while the oxygen-containing gas passes through the reaction zone in a countercurrent manner. Oxygen-containing gas is introduced from the bottom of reaction section 13 and fed into the reactor through gas distributor 7 . The gas distributor 7 is the head at the bottom, which can form the required oxygen in the liquid phase reaction zone. This mode is conducive to improving the selectivity of the target product, because the oxidation mechanism of 2,6-diisopropylnaphthalene is relatively complicated, and it needs to undergo the oxidation of monoisopropyl to ketone or ketol, followed by oxidation to acid, and then the second The isopropyl group is correspondingly oxidized to acid through this step, and the side reaction of peroxidation leads to the breakage of the naphthalene ring to generate trimellitic acid, so the reaction zone is used to directly feed the gas to fully achieve the raw material, catalyst and oxygen-containing gas. Mixing can well control the oxidation reaction toward the target product, fully reduce the content of by-products, and increase the yield and purity of the target product.

The gas distribution charged into the reactor plays a very important role in the oxidation reaction, as shown in Fig. 2 and Fig. 3, the schematic diagrams of two schemes of embodiment of nozzle layout of gas distributor 7, the important structure of the present invention.

In the first embodiment, four nozzles 71 are evenly distributed at 1/2 radius R from the center, or one nozzle 71 is at the center, and three nozzles 71 are evenly distributed at 1/1 radius R from the center.

In the second embodiment, eight nozzles 71 are evenly distributed at 1/2 radius R from the center, or four nozzles 71 are evenly distributed at 1/3 radius R from the center, and evenly distributed at 2/3 radius R from the center. Four spray pipes 71, and both are mutually staggered.

Figure 4 shows the oxidation flow diagram of 2,6-dialkylnaphthalene, which shows the position and function of the present invention in the oxidation scheme.

Claims (3)

1. A vertical bubbling oxidation reaction device for synthesizing naphthalene dicarboxylic acid, mainly composed of a straight cylinder (1), a top cover (2), a bottom cover (3), a liquid distributor (4), and a structured packing (5) , reaction solution (6), gas distributor (7), feed inlet (8) and discharge outlet (9) composition, it is characterized in that: straight cylinder body (1) is straight cylindrical structure, and its length is L, and inner wall diameter For D, the length L of the straight barrel (1) should include the length of the rectifying section (11) that oxidation reaction needs, the length of free section (12) and the length H of reaction section (13), the length of its reaction section (13) Length H should be (60～90)% of length L of straight body (1), preferably (70～80)%, and H/D=2～8; The length of the free section (12) should be (10～20)% of the length L of the straight cylinder (1); the position of the rectifying section (11) is provided with a specific surface area α=400～1500, and the void ratio ε= 0.90～0.98, preferably the internal member of the structured packing with specific surface area α=600～1200 and porosity ε=0.92～0.96; the volume of the reaction solution (6) filled in the straight cylinder (1) should be the volume of the straight cylinder (1) (40～50)%; a liquid distributor (4) is arranged on the top of the straight cylinder (1), a top cover (2) is installed on it, a bottom cover (3) is installed on the bottom, and a head is sealed at the bottom A gas distributor (7) consisting of (4-8) nozzle pipes (71) uniformly distributed from the center of the bottom end is arranged at the center, and its total cross-sectional area is (0.5-5) of the cross-sectional area of the straight cylinder (1). %, preferably (1～3)%, every nozzle (71) outlet gas velocity is (3～15) m/s, preferably (6～10) m/s; /2～2/3) A feed inlet (8) is provided at L, and a discharge outlet (9) is provided at the bottom of the straight cylinder (1); the overall structure of the straight cylinder (1) should be able to withstand (170～240) ℃ temperature and (0.8 ~ 4) Mpa pressure. 2. The vertical bubbling oxidation reaction device for synthesizing naphthalene dicarboxylic acid according to claim 1 is characterized in that: the gas distributor (7) is that four nozzles (71) are evenly spaced from the central 1/2 radius R place Distribution, or one nozzle pipe (71) at the center, and three nozzle pipes (71) evenly distributed at the 1/2 radius R from the center. 3. The vertical bubbling oxidation reaction device for synthesizing naphthalene dicarboxylic acid according to claim 1 is characterized in that: the gas distributor (7) is that eight nozzles (71) are evenly spaced from the central 1/2 radius R place Distribution, or evenly distribute four nozzles (71) at the 1/3 radius R from the center, and evenly distribute the other four nozzles (71) at the 2/3 radius R from the center, and the two are staggered from each other.

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