Liquid phase adsorption separation system and application thereof

Abstract

The invention relates to a liquid phase adsorption separation system and application thereof, the system comprises an adsorption tower body and three or more adsorbent bed layers arranged in the adsorption tower body, and a mixing-distribution internal component is arranged between two adjacent adsorbent bed layers; the mixing-distribution internal component comprises an upper supporting grating, a middle mixing-distributor and a lower supporting grating; the middle mixing-distributor comprises a feeding and discharging pipe, a feeding and discharging conical distribution chamber, a conical mixing chamber and a conical discharging chamber; the feeding and discharging pipe penetrates through the upper supporting grating and the adsorption tower body and is communicated with the outside, the feeding and discharging conical distribution chamber is communicated with the feeding and discharging pipe, the conical mixing chamber is arranged below the feeding and discharging conical distribution chamber and is communicated with the feeding and discharging conical distribution chamber, and the conical discharging chamber is arranged below the conical mixing chamber and is communicated with the conical mixing chamber. Compared with the prior art, the method has the advantages of low production cost, high product purity, high yield and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of adsorption separation, and in particular to a liquid-phase adsorption separation system and its application. Background Art

[0002] The three isomers of dichlorobenzene: ortho-dichlorobenzene, meta-dichlorobenzene and para-dichlorobenzene are all important organic chemical raw materials. Ortho-dichlorobenzene is mainly used as an organic synthesis raw material, a solvent for dye manufacturing, a cleaning agent, a solvent for wax and tar, etc., and is also used as a raw material for synthesizing pesticides, etc.; para-dichlorobenzene is mainly used for the synthesis of pesticides, preservatives and solvents, etc.; meta-dichlorobenzene is widely used as an intermediate for synthesizing dyes, pharmaceuticals, pesticides, etc., and is the main raw material for the fungicides imazalil, propiconazole and difenoconazole. Dichlorobenzene is mainly synthesized by the chlorination reaction of benzene or chlorobenzene. However, in the chlorination reaction of benzene or chlorobenzene, mainly ortho-dichlorobenzene and para-dichlorobenzene are obtained, and very little meta-dichlorobenzene is obtained. Meta-dichlorobenzene is mainly obtained by the isomerization of ortho-dichlorobenzene or para-dichlorobenzene. Through the isomerization reaction of ortho-dichlorobenzene or para-dichlorobenzene, a mixture of the three dichlorobenzene isomers of ortho, meta and para is obtained. Traditionally, the above isomerization reaction uses solid aluminum trichloride as a catalyst, and the isomerization reaction is carried out in a batch reactor, adopting a batch production method. The reaction product is then washed with water and de-coked to obtain the isomerization product. Among the three dichlorobenzene isomers, the boiling point of ortho-dichlorobenzene is 179 °C, the boiling point of para-dichlorobenzene is 174 °C, the melting point is 53 °C, and the boiling point of meta-dichlorobenzene is between 171-173 °C, and the melting point is -24 °C. Therefore, traditionally, ortho-dichlorobenzene is separated by distillation, para-dichlorobenzene is separated by crystallization, and the remaining meta-dichlorobenzene is then obtained by distillation. Using the above traditional production method of meta-dichlorobenzene, not only is the isomerization reaction a batch production, generating a large amount of wastewater, but also the distillation and crystallization separation consume a large amount of energy. At the same time, the production process is long, the three wastes emissions are large, the equipment investment is large, the production cost is high, and it is uneconomical.

[0003] In recent years, a large number of studies on the production methods of m-dichlorobenzene have been conducted at home and abroad. Patent CN112452103A describes a method for producing high-purity m-dichlorobenzene by gas-phase adsorption separation. This method uses MFI zeolite and X-type zeolite as adsorbents to adsorb p-dichlorobenzene and o-dichlorobenzene, and the unadsorbed is m-dichlorobenzene, with the purity of the obtained m-dichlorobenzene being 95.5%. This method is a gas-phase adsorption, which requires a large amount of gasification heat, cooling water, etc., resulting in high energy consumption, and the purity of m-dichlorobenzene is relatively low. Patent CN1315217A discloses a method for liquid-phase selective adsorption separation of mixed dichlorobenzenes using hydrophobic silicalite zeolite. This method uses an MFI-type hydrophobic silicalite zeolite molecular sieve adsorbent to adsorb o-dichlorobenzene and / or p-dichlorobenzene, and the unadsorbed is m-dichlorobenzene, but this method does not clearly state what purity the obtained m-dichlorobenzene reaches. Neither of the above two patents clearly defines the specific structure of the adsorption tower equipment and the adsorption efficiency. EP0334025A1 discloses a method for separating isomers of halogenated benzene derivatives. In its examples, it is described that first, o-dichlorobenzene is liquid-phase isomerized to three isomers of dichlorobenzene under the action of a ZSM-5 molecular sieve catalyst in a fixed-bed reactor, and then separated by a simulated moving-bed adsorption tower to obtain an m-dichlorobenzene product, with the purity of m-dichlorobenzene reaching 99.5% and the recovery rate reaching 95%. Patents such as JP04330025, JP11158093, JP11180911, JP11335308, etc. disclose a method for separating dichlorobenzene isomers using a simulated moving-bed adsorption tower to obtain high-purity m-dichlorobenzene. An adsorbent is prepared using ion-modified Y-type zeolite or other molecular sieves to adsorb o-dichlorobenzene and p-dichlorobenzene, and the unadsorbed m-dichlorobenzene is obtained as a high-purity product after rectification. Patent US4996380A discloses another method for adsorption separation of dichlorobenzene isomers. An adsorbent is prepared using ion-modified X-type zeolite to adsorb m-dichlorobenzene, and the unadsorbed are o-dichlorobenzene and p-dichlorobenzene. After removing m-dichlorobenzene with a desorbent, a high-purity m-dichlorobenzene product is obtained. None of the above patents clearly define the structure of the adsorption tower equipment and the fluid distribution inside it.

[0004] Patents such as US6156197A, WO2006 / 055222A1, CN1131394A, CN101056684A, CN201592090U, CN103084084B, etc. disclose a fluid mixing and distribution device or component, which can be used in equipment filled with multiple sections of packing or adsorbent. For the components disclosed in the above patents, when the fluid is mixed and then distributed, baffles are provided at the mixing point or the fluid outlet after mixing to prevent the fluid from flowing out directly and impacting the lower packing or adsorbent, thus forming a fluid distribution blind area under the baffle. In addition, in order to obtain a relatively uniform fluid distribution, the above patents divide the entire adsorption tower into several different regions. However, when the fluid is mixed and then distributed within each region, different flow rates are not designed according to the distance of distribution, so there is still uneven distribution within each region. Summary of the Invention

[0005] The object of the present invention is to provide a liquid phase adsorption separation system and its application, with more reasonable fluid mixing - distribution and higher adsorption efficiency.

[0006] The object of the present invention can be achieved by the following technical solutions: A liquid phase adsorption separation system includes an adsorption tower body and three or more adsorbent beds arranged in the adsorption tower body, and a mixing - distribution internal component is provided between two adjacent adsorbent beds; The mixing - distribution internal component includes an upper support grid, an intermediate mixing - distributor, and a lower support grid; The intermediate mixing - distributor includes a feed - discharge pipe, a feed - discharge conical distribution chamber, a conical mixing chamber, and a conical discharge chamber. The feed - discharge conical distribution chamber, the conical mixing chamber, and the conical discharge chamber are all arranged between the upper support grid and the lower support grid; The feed - discharge pipe passes through the upper support grid and the adsorption tower body and communicates with the outside. The feed - discharge conical distribution chamber is connected to the feed - discharge pipe. The conical mixing chamber is arranged below the feed - discharge conical distribution chamber and is connected to the feed - discharge conical distribution chamber. The conical discharge chamber is arranged below the conical mixing chamber and is connected to the conical mixing chamber.

[0007] Preferably, the feed - discharge conical distribution chamber includes a half - pipe and two perforated plates; The two perforated plates form a conical structure, and the half - pipe is arranged at the top of the conical structure and is connected to the feed - discharge pipe.

[0008] Further preferably, the cone angle of the conical structure is 30° - 60°.

[0009] Further preferably, each perforated plate has 3 - 6 rows of holes, the hole diameter is 2 - 25 mm, the hole pitch is 4 - 15 times the hole diameter, and the hole flow velocity of the perforated holes is 3.0 - 10.0 m / s.

[0010] Preferably, the conical mixing chamber includes two conical mixing chamber partition plates and two inclined conical mixing chamber baffle plates; One end of the conical mixing chamber partition plate is fixed, and the other end is connected to the conical mixing chamber baffle plate. A mixing channel is formed between the conical mixing chamber baffle plate and the inlet / outlet conical distribution chamber, and a conical mixing chamber outlet is formed between the bottoms of the two conical mixing chamber baffle plates.

[0011] More preferably, one end of the conical mixing chamber partition plate is connected to the adsorption tower body or the intermediate support pipe, and the other end is connected to the conical mixing chamber baffle plate.

[0012] More preferably, the conical mixing chamber baffle plate is parallel to the perforated plate of the inlet / outlet conical distribution chamber.

[0013] More preferably, the flow rate in the mixing channel is 1.5 - 3.5 m / s.

[0014] More preferably, the flow rate at the conical mixing chamber outlet is 0.5 - 1.5 m / s.

[0015] Preferably, the conical discharging chamber includes two inclined conical discharging chamber baffle plates, and a discharging channel is formed between the conical discharging chamber baffle plates and the conical mixing chamber.

[0016] More preferably, the conical discharging chamber baffle plate is parallel to the conical mixing chamber baffle plate.

[0017] More preferably, the outlet flow rate at the tapered end of the discharging channel is 0.1 - 0.5 m / s.

[0018] More preferably, the two conical discharging chamber baffle plates are provided with 3 - 6 rows of holes, and the aperture of the holes gradually increases from the tapered end to the tail end. The aperture of the holes near the tapered end is 2 - 5 mm, the aperture of the holes near the tail end is 10 - 15 mm, and the aperture of the holes in the middle is 5 - 10 mm.

[0019] Even more preferably, the flow rate of the holes at the tail end is 0.1 - 0.5 m / s, the flow rate of the holes at the tapered end is 0.5 - 1.0 m / s, and the flow rate of the holes in the middle is between the former two.

[0020] Preferably, the mixing - distribution internal member is divided into 2 - 20 sub - internal members with equal areas. Each sub - internal member is isolated by a partition plate, and each sub - internal member is provided with an intermediate mixing - distributor.

[0021] Preferably, the adsorbent bed layer is 3 - 20 layers, and the adsorbent bed layer is filled with adsorbent.

[0022] More preferably, the adsorbent is solid particles.

[0023] An application of the above liquid-phase adsorption separation system, which uses the liquid-phase adsorption separation system for the production of high-purity m-dichlorobenzene, includes the following steps: Fresh feed enters the feed and discharge conical distribution chamber through the first-layer feed and discharge pipe, and then flows into the mixing channel through the perforated plate of the feed and discharge conical distribution chamber. The circulating material in the adsorption tower body passes through different adsorbent beds and mixing-distribution internal components from top to bottom, and then is blocked by the baffle of the conical mixing chamber and can only enter the mixing channel of the conical mixing chamber, where it is completely mixed evenly with the fresh feed. The evenly mixed fluid flows out through the outlet of the conical mixing chamber and enters the conical discharge chamber, and the fluid flows out through the openings of the baffle of the conical discharge chamber and the discharge channel; The fresh feed contains o-dichlorobenzene, p-dichlorobenzene and m-dichlorobenzene; The circulating material contains o-dichlorobenzene, p-dichlorobenzene and m-dichlorobenzene; The fresh feed and the circulating material are adsorbed through at least N layers (N is not less than 3) of adsorbent beds, and the raffinate after adsorption is drawn out from the (N + 1)-layer feed and discharge pipe; Preferably, a circulation pipeline and a circulation pump are provided outside the adsorption tower body, and the circulation pipeline and the circulation pump circulate the fluid flowing out from the bottom head of the adsorption tower body to the upper part as the circulating material.

[0024] In the present invention, the circulating material is a mixture of o-dichlorobenzene, p-dichlorobenzene and m-dichlorobenzene circulated from an external circulation pump of the tower.

[0025] Preferably, the adsorbent filled in the adsorbent bed is an adsorbent for adsorbing o-dichlorobenzene and p-dichlorobenzene or an adsorbent for adsorbing m-dichlorobenzene.

[0026] In the present invention, after the fresh feed and the circulating material are processed by the system of the present invention, o-dichlorobenzene and p-dichlorobenzene or m-dichlorobenzene are adsorbed by the adsorbent, and the raffinate is m-dichlorobenzene and the desorbent remaining in the adsorbent or o-dichlorobenzene and p-dichlorobenzene and the desorbent remaining in the adsorbent. The desorbent is separated and recycled, and at the same time, high-purity m-dichlorobenzene products or a mixture of o-dichlorobenzene and p-dichlorobenzene are obtained.

[0027] Further preferably, the adsorbent filled in the adsorbent bed is an adsorbent for adsorbing o-dichlorobenzene and p-dichlorobenzene.

[0028] Further preferably, the adsorbent is an X-type molecular sieve, Y-type molecular sieve, ZSM series molecular sieve, or SAPO series molecular sieve modified with a Group IA or Group IIA metal.

[0029] Preferably, the adsorption temperature is 150-250 °C and the adsorption pressure is 0.5-1.5 MPa.

[0030] Preferably, the application of the liquid-phase adsorption separation system further includes the following steps: After 50 to 250 seconds of starting the fresh feed, the fresh feed is stopped, and the desorbent enters the inlet / outlet conical distribution chamber from the inlet / outlet pipe of the first layer, and then along the same channel as the fresh feed, the o-dichlorobenzene, p-dichlorobenzene or m-dichlorobenzene adsorbed in the adsorbent is desorbed. The desorbed liquid after desorption is drawn out from the inlet / outlet pipe of the (N + 1)-th layer (N is not less than 3).

[0031] In the present invention, the desorbed liquid includes o-dichlorobenzene, p-dichlorobenzene and desorbent or m-dichlorobenzene and desorbent. The desorbent is separated and recycled, and at the same time, a mixture of o-dichlorobenzene and p-dichlorobenzene or a high-purity m-dichlorobenzene product is obtained. At this time, the desorbent remains in the adsorbent.

[0032] The mixture of o-dichlorobenzene and p-dichlorobenzene separated from the raffinate or desorbed liquid can be recycled to the system of the present invention or to the dichlorobenzene isomerization unit to increase the production of m-dichlorobenzene.

[0033] Further preferably, the desorbent is chlorobenzene, dichlorotoluene, xylene or a mixture thereof.

[0034] Further preferably, the desorption temperature is 150 - 250 °C and the desorption pressure is 0.5 - 1.5 MPa.

[0035] The present invention provides an adsorption tower device for preparing m-dichlorobenzene, which mainly solves the problems of uneven fluid mixing and blind spots in the distribution in the adsorption tower in the prior art for preparing m-dichlorobenzene.

[0036] An application of the above liquid-phase adsorption separation system, using the liquid-phase adsorption separation system for producing high-purity p-xylene, includes the following steps: The fresh feed enters the inlet / outlet conical distribution chamber from the inlet / outlet pipe of the first layer, and then flows into the mixing channel from the perforated plate of the inlet / outlet conical distribution chamber. The circulating material in the adsorption tower body passes through different adsorbent beds and mixing-distribution internal components from top to bottom, and then is blocked by the baffle of the conical mixing chamber and can only enter the mixing channel of the conical mixing chamber to be completely mixed evenly with the fresh feed. The evenly mixed fluid flows out from the outlet of the conical mixing chamber and enters the conical discharging chamber, and the fluid flows out through the openings of the baffle of the conical discharging chamber and the discharging channel. The fresh feed contains o-xylene, p-xylene and m-xylene; The circulating material contains o-xylene, p-xylene and m-xylene.

[0037] Preferably, the adsorbent filled in the adsorbent bed is an adsorbent for adsorbing p-xylene.

[0038] Further preferably, the adsorbent is an X-type molecular sieve, Y-type molecular sieve, ZSM series molecular sieve, SAPO series molecular sieve modified with a Group IA or Group IIA metal.

[0039] After being processed by the system of the present invention, p-xylene is adsorbed by the adsorbent, and the raffinate is o-xylene, m-xylene and the desorbent remaining in the adsorbent. The desorbent is separated and recycled, and at the same time, a mixture of o-xylene and m-dichlorobenzene is obtained.

[0040] Preferably, when the liquid-phase adsorption separation system is used for producing high-purity p-xylene, the following steps are further included: After 50 seconds to 250 seconds of starting fresh feed, the fresh feed is stopped, and the desorbent enters the feed and discharge conical distribution chamber from the feed and discharge pipe of the first layer, and then desorbs the p-xylene adsorbed in the adsorbent along the same channel as the fresh feed; The desorbed desorbate is withdrawn from the feed and discharge pipe of the (N + 1)-th layer (N is not less than 3).

[0041] In the present invention, the desorbate includes p-xylene and the desorbent. The desorbent is separated and recycled, and at the same time, a high-purity p-xylene product is obtained. At this time, the desorbent remains in the adsorbent.

[0042] The mixture of o-xylene and m-xylene separated from the raffinate or the desorbate can be recycled to the system of the present invention or to the xylene isomerization unit to further increase the production of p-xylene.

[0043] Further preferably, the desorbent is toluene, diethylbenzene or a mixture thereof.

[0044] Further preferably, the desorption temperature is 150 - 250 °C, and the desorption pressure is 0.5 - 1.5 MPa.

[0045] Compared with the prior art, the present invention has the following beneficial effects: 1. In the adsorption tower body of the present invention, the fluid is evenly mixed, and the conical discharge structure avoids the formation of a distribution blind area of the fluid in the tower, and can solve the problems of uneven fluid mixing and low adsorption efficiency in the traditional adsorption tower equipment. The fluid mixing - distribution is more reasonable and the adsorption efficiency is higher; 2. The present invention contains multiple sections of adsorbent beds, and mixing - distribution internal components are installed between the beds. When designing this internal component, different hole flow velocities are designed for different distribution distances, and the blind area of fluid distribution is avoided, which has the advantages of uniform distribution and high adsorption efficiency; 3. The present invention is a liquid-phase adsorption process, which avoids the equipment investment and energy consumption of gasification, condensation, etc., and has the advantages of small investment and low energy consumption; 4. The present invention has a high adsorption efficiency, the obtained m-dichlorobenzene has a purity greater than 99.5%, and the recovery rate of m-dichlorobenzene can reach more than 95%; 5. The present invention is applicable to the production of high-purity m-dichlorobenzene or the production of high-purity p-xylene. Description of the Drawings

[0046] Figure 1 It is a schematic partial longitudinal section view of the liquid-phase adsorption separation system of the present invention; Figure 2 It is a schematic structural view of the mixing-distribution internal component of the present invention; Figure 3 It is a schematic structural view of the inlet / outlet conical distribution chamber in the mixing-distribution internal component of the present invention; Figure 4 It is a schematic structural view of the conical mixing chamber in the mixing-distribution internal component of the present invention; Figure 5 It is a schematic structural view of the conical discharge chamber in the mixing-distribution internal component of the present invention; Figure 6 It is a schematic cross-sectional view of the adsorption tower body of the present invention, and can be obtained by longitudinally cutting along the A-A direction Figure 1 ; In the figure: 1 - adsorption tower body, 2 - adsorbent bed layer, 3 - mixing-distribution internal component, 31 - upper support grid, 32 - intermediate mixing-distributor, 321 - inlet / outlet pipe, 322 - inlet / outlet conical distribution chamber, 3221 - half pipe, 3222 - perforated plate, 3223 - holes in the perforated plate, 323 - conical mixing chamber, 3231 - partition plate of the conical mixing chamber, 3232 - baffle of the conical mixing chamber, 3233 - mixing channel, 3234 - outlet of the conical mixing chamber, 324 - conical discharge chamber, 3241 - baffle of the conical discharge chamber, 3242 - discharge channel, 3243 - holes in the baffle, 33 - lower support grid, 4 - partition plate, 5 - intermediate support pipe. Specific embodiments

[0047] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented on the premise of the technical solution of the present invention, and gives detailed implementation manners and specific operation processes, but the protection scope of the present invention is not limited to the following embodiments.

[0048] Example 1 A liquid-phase adsorption separation system includes an adsorption tower body 1, an adsorbent bed layer 2, and a mixing-distribution internal component 3.

[0049] Among them, the mixing-distribution internal component 3 includes an upper support grid 31, an intermediate mixing-distributor 32, and a lower support grid 33. The intermediate mixing-distributor 32 includes an inlet / outlet pipe 321, an inlet / outlet conical distribution chamber 322, a conical mixing chamber 323, and a conical discharge chamber 324.

[0050] Specifically, there are more than three adsorbent beds 2 provided in the adsorption tower body 1. The mixing-distribution internal member 3 is arranged between two adjacent adsorbent beds 2. The upper support grid 31 is arranged at the bottom of the upper adsorbent bed 2, and the lower support grid 33 is arranged at the top of the lower adsorbent bed 2. The inlet / outlet conical distribution chamber 322, the conical mixing chamber 323 and the conical outlet chamber 324 of the intermediate mixing-distributor 32 are arranged between the upper support grid 31 and the lower support grid 33. The inlet / outlet pipe 321 passes through the upper support grid 31 and the adsorption tower body 1 and communicates with the outside. The inlet / outlet conical distribution chamber 322 is communicated with the inlet / outlet pipe 321. The conical mixing chamber 323 is arranged below the inlet / outlet conical distribution chamber 322 and is communicated with the inlet / outlet conical distribution chamber 322. The conical outlet chamber 324 is arranged below the conical mixing chamber 323 and is communicated with the conical mixing chamber 323.

[0051] The mixed dichlorobenzene containing ortho-dichlorobenzene, para-dichlorobenzene and meta-dichlorobenzene can be separated by using the liquid-phase adsorption separation system of this embodiment to produce high-purity meta-dichlorobenzene.

[0052] Specifically, it may include the following steps: During adsorption, fresh mixed dichlorobenzene enters the inlet / outlet conical distribution chamber 322 from the inlet / outlet pipe 321, and then enters the conical mixing chamber 323. The circulating material in the adsorption tower body 1 passes through different adsorbent beds 2 and the mixing-distribution internal member 3 from top to bottom and also enters the conical mixing chamber 323. The fresh mixed dichlorobenzene and the circulating material are evenly mixed in the conical mixing chamber 323 and then flow out through the conical outlet chamber 324, passing through the next lower adsorbent bed 2 and the mixing-distribution internal member 3 from top to bottom. After passing through N layers (N is not less than 3) of adsorbent beds 2 and the mixing-distribution internal member 3, the raffinate is drawn out from the inlet / outlet pipe 321 of the N+1 layer, and the rest is circulated from the lower part of the adsorption tower body 1 to the upper part of the adsorption tower by an external circulating device and re-enters the adsorption tower body 1 as the circulating material.

[0053] During desorption, the fresh mixed dichlorobenzene is replaced with a desorbent, and the path through which the desorbent passes is the same as that of the fresh mixed dichlorobenzene. The desorbate is drawn out from the inlet / outlet pipe 321 of the N+1 layer.

[0054] Embodiment 2 An adsorption tower device for preparing meta-dichlorobenzene, as Figure 1 shown, includes three or more adsorbent beds 2, and a mixing-distribution internal member 3 is installed between every two adsorbent beds 2; as Figure 2 shown, this internal member is composed of an upper support grid 31, an intermediate mixing-distributor 32, and a lower support grid 33; the intermediate mixing-distributor 32 is composed of an inlet / outlet pipe 321, an inlet / outlet conical distribution chamber 322, a conical mixing chamber 323, and a conical outlet chamber 324.

[0055] The adsorbent bed 2 is preferably 3 - 20 layers, and the adsorbent bed 2 is filled with an adsorbent for adsorbing ortho - dichlorobenzene and para - dichlorobenzene or an adsorbent for adsorbing meta - dichlorobenzene.

[0056] The adsorbent is preferably an X - type molecular sieve, Y - type molecular sieve, ZSM series molecular sieve, or SAPO series molecular sieve modified with Group IA or Group IIA metals.

[0057] As Figure 3 shown, the inlet - outlet conical distribution chamber 322 of the intermediate mixing - distributor 32 is composed of a half - pipe 3221 and two perforated plates 3222; preferably, each of the two perforated plates 3222 has 3 - 6 rows of holes (hole plate openings 3223), the hole diameter is preferably 2 - 25 mm, the hole pitch is preferably 4 - 15 times the hole diameter, the hole flow velocity of the openings is preferably 3.0 - 10.0 m / s, and the hole flow velocity of the openings is proportional to the distance from the opening position to the tower wall or the partition plate 4.

[0058] Specifically, the top of the inlet - outlet conical distribution chamber 322 of the intermediate mixing - distributor 32 is a half - pipe structure (half - pipe 3221), which can ensure that there is no static area at the top of the inlet - outlet conical distribution chamber 322; the two side perforated plates (perforated plates 3222) are perforated, and the hole flow velocity of the openings is proportional to the distance from the opening position to the tower wall or the partition plate 4. The farther the opening position is from the tower wall or the partition plate 4, the greater the hole flow velocity, and vice versa; this design can ensure that the fluid reaches the tower wall or the partition plate 4 at the same time, ensuring uniform fluid distribution.

[0059] As Figure 4 shown, the conical mixing chamber 323 of the intermediate mixing - distributor 32 is composed of two partition plates (conical mixing chamber partition plates 3231) and two inward - inclined baffle plates (conical mixing chamber baffle plates 3232); the two baffle plates and the inlet - outlet conical distribution chamber 322 form a mixing channel 3233, and the flow velocity of the mixing channel is preferably 1.5 - 3.5 m / s; the flow velocity at the outlet 3234 of the conical mixing chamber is preferably 0.5 - 1.5 m / s.

[0060] Specifically, the left and right two partition plates (conical mixing chamber partition plates 3231) of the conical mixing chamber 323 of the intermediate mixing - distributor 32 divide the fluid in the adsorption tower, and it can only flow through the mixing channel 3233 composed of two inward - inclined baffle plates (conical mixing chamber baffle plates 3232) and the inlet - outlet conical distribution chamber 322. The feed is ejected from the baffle openings of the conical distribution chamber and mixed with the fluid flowing up and down in the adsorption tower in the two - side mixing channels 3233 of the mixing chamber, and then flows out through the bottom outlet (conical mixing chamber outlet 3234) of the conical mixing chamber 323, and the flow velocity at the outlet is lower than that at the mixing channel 3233, which can ensure that there is no back - mixing or back - flow of the fluid. This design can ensure sufficient mixing of the feed and the fluid in the adsorption tower.

[0061] As Figure 5As shown, the conical discharge chamber 324 of the intermediate mixing-distributor 32 is composed of two outwardly inclined baffles (conical discharge chamber baffles 3241); preferably, each of the two baffles is provided with 3-6 rows of holes (baffle holes 3243), and the aperture of the holes gradually increases from the tip of the cone to the tail of the cone. The aperture of the holes near the tip of the cone is preferably 2-5 mm, the aperture of the holes near the tail of the cone is preferably 10-15 mm, and the aperture of the holes in the middle is preferably 5-10 mm; the flow velocity of the holes at the tail of the cone is preferably 0.1-0.5 m / s, the flow velocity of the holes at the tip of the cone is preferably 0.5-1.0 m / s, and the flow velocity of the holes in the middle is between the former two.

[0062] Specifically, the two outwardly inclined baffles (conical discharge chamber baffles 3241) of the conical discharge chamber 324 of the intermediate mixing-distributor 32 and the conical mixing chamber 323 form discharge channels 3242 on both sides; holes (baffle holes 3243) are opened on the two baffles, and the aperture of the holes gradually increases from the tip of the cone to the tail of the cone, so that the flow velocity of the holes at the tip of the cone is greater than that at the tail of the cone; the fluid flows out through the holes on the two baffles and the discharge channels 3242 on both sides, and the discharge resistance is greater near the tip of the cone. This design can ensure uniform flow rate at each discharge position and prevent local deviation flow. In addition, this conical structure design avoids the formation of a static area at the bottom of the discharge chamber.

[0063] According to the size of the adsorption tower and the treatment scale, the mixing-distribution internal component 3 can be divided into multiple pieces with equal areas, such as Figure 6 As shown, for the installation of the internal component or uniform distribution of the fluid; each internal component is isolated by a partition plate 4, and each internal component is separately provided with an intermediate mixing-distributor 32 and an inlet and outlet pipe 321. This design avoids the situation of uneven fluid distribution caused by using a single internal component for an oversized tower equipment.

[0064] Specifically, an intermediate support pipe 5 is provided at the center of the adsorption tower, and both ends of the internal component are fixed through the tower wall and the intermediate support pipe 5.

[0065] The mixing-distribution internal component 3 of the adsorption tower equipment is preferably divided into 2-20 pieces with equal areas.

[0066] The adsorption tower is used in the process for preparing m-dichlorobenzene. The adsorbent preferably adsorbs o-dichlorobenzene and p-dichlorobenzene, and the raffinate is m-dichlorobenzene; the adsorption temperature is preferably 150-250 °C, and the adsorption pressure is preferably 0.5-1.5 MPa.

[0067] The adsorption tower is used in the process for preparing m-dichlorobenzene. The desorbent is preferably chlorobenzene, dichlorotoluene, xylene or a mixture thereof, the desorption temperature is preferably 150-250 °C, and the desorption pressure is preferably 0.5-1.5 MPa.

[0068] The above operating conditions can ensure that the adsorption is carried out in a liquid phase environment.

[0069] This embodiment provides an adsorption tower device for preparing high-purity m-dichlorobenzene, which can be used to prepare high-purity m-dichlorobenzene products.

[0070] Specifically, fresh feed enters the inlet and outlet conical distribution chamber 322 from the inlet and outlet pipe 321, and then flows into the mixing channel 3233 through the orifice openings 3223 of the orifice plate 3222 of the perforated plate; the circulating material in the adsorption tower passes through different adsorbent beds 2 and the mixing-distribution internal components 3 from top to bottom, and then is blocked by the conical mixing chamber partition 3231 and can only enter the mixing channel 3233 of the conical mixing chamber 323, where it is completely mixed evenly with the fresh feed; the evenly mixed fluid flows out through the outlet 3234 of the conical mixing chamber and enters the conical discharge chamber 324; the fluid flows out through the baffle openings 3243 and the discharge channel 3242 of the conical discharge chamber 324; the baffle openings 3243 have different pore diameters, so that the outlet resistance is greater closer to the cone tip, preventing the formation of uneven flow when the fluid flows out.

[0071] Example 3 The adsorption tower device described in Example 2 is used to prepare m-dichlorobenzene. The diameter of the adsorption tower is 1.6 meters, and it is filled with 12 layers of adsorbent, and the height of each adsorbent bed is 500 millimeters; the adsorbent is 13X molecular sieve modified with calcium nitrate and potassium hydroxide. The mixing-distribution internal components are divided into 4 equal-area blocks. The orifice plate of the inlet and outlet conical distribution chamber of the middle mixing-distributor has 3 rows of holes, the orifice diameter is 3.5 millimeters, the hole spacing is 21 millimeters, and the calculated hole flow rate is 3.0 - 9.0 m / s. The designed flow rate of the mixing channel in the conical mixing chamber of the middle mixing-distributor is 2.0 m / s, and the flow rate at the outlet of the conical mixing chamber is 1.0 m / s. The baffle of the conical discharge chamber has 3 rows of holes, the orifice diameter at the cone tip is 2.0 millimeters, the orifice diameter at the cone tail is 10.0 millimeters, and the orifice diameter in the middle is 5.0 millimeters.

[0072] 10 kg of raw material mixed dichlorobenzene (o-dichlorobenzene:p-dichlorobenzene:m-dichlorobenzene = 3:3:4) enters the adsorption tower through the inlet and outlet pipe 321. The adsorption temperature is 200 °C, and the adsorption pressure is 1.0 MPa; during desorption, the adsorption tower is filled with the desorbent 3,4-dichlorotoluene, the desorption temperature is 250 °C, and the desorption pressure is 0.5 MPa.

[0073] The collected raffinate is o-dichlorobenzene and p-dichlorobenzene, with a weight of 6.11 kg; the collected desorbate is m-dichlorobenzene, with a purity of 99.65% and a weight of 3.89 kg. The calculated recovery rate of m-dichlorobenzene is 97.25%.

[0074] Example 4 The meta - dichlorobenzene is prepared using the adsorption tower equipment described in Example 2. The diameter of the adsorption tower is 3.6 meters, and it is filled with 6 layers of adsorbents. The height of each adsorbent bed layer is 500 millimeters; the adsorbent is 13X molecular sieve modified by calcium nitrate and lithium hydroxide. The mixing - distribution internal component is divided into 8 equal - area blocks. The orifice plate of the inlet - outlet conical distribution chamber of the middle mixing - distributor has 3 rows of holes, the hole diameter is 5.0 millimeters, the hole pitch is 30 millimeters, and the calculated hole flow velocity is 5.0 - 10.0 m / s. The flow velocity of the mixing channel designed in the conical mixing chamber of the middle mixing - distributor is 2.5 m / s, and the flow velocity at the outlet of the conical mixing chamber is 1.5 m / s. The baffle of the conical discharge chamber has 3 rows of holes, the hole diameter at the tip of the cone is 2.0 millimeters, the hole diameter at the tail of the cone is 15.0 millimeters, and the hole diameter in the middle is 8.0 millimeters.

[0075] 100 kg of raw material mixed dichlorobenzene (o - dichlorobenzene:p - dichlorobenzene:m - dichlorobenzene = 3:3:4) enters the adsorption tower through the inlet - outlet pipe 321. The adsorption temperature is 160 °C, and the adsorption pressure is 0.8 MPa; during desorption, the adsorption tower is filled with the desorbent 3,4 - dichlorotoluene, the desorption temperature is 180 °C, and the desorption pressure is 0.6 MPa.

[0076] The collected raffinate is meta - dichlorobenzene, with a purity of 99.55% and a weight of 38.2 kg. The calculated recovery rate of meta - dichlorobenzene is 95.5%; the weight of the collected desorbent (o - dichlorobenzene and p - dichlorobenzene) is 61.8 kg.

[0077] Example 5 The meta - dichlorobenzene is prepared using the adsorption tower equipment described in Example 2. The diameter of the adsorption tower is 2.5 meters, and it is filled with 10 layers of adsorbents. The height of each adsorbent bed layer is 500 millimeters; the adsorbent is ZSM - 5 molecular sieve modified by sodium nitrate and lithium hydroxide. The mixing - distribution internal component is divided into 6 equal - area blocks. The orifice plate of the inlet - outlet conical distribution chamber of the middle mixing - distributor has 3 rows of holes, the hole diameter is 10.0 millimeters, the hole pitch is 50 millimeters, and the calculated hole flow velocity is 3.0 - 8.0 m / s. The flow velocity of the mixing channel designed in the conical mixing chamber of the middle mixing - distributor is 1.8 m / s, and the flow velocity at the outlet of the conical mixing chamber is 1.1 m / s. The baffle of the conical discharge chamber has 3 rows of holes, the hole diameter at the tip of the cone is 3.0 millimeters, the hole diameter at the tail of the cone is 12.0 millimeters, and the hole diameter in the middle is 6.0 millimeters.

[0078] 50 kg of raw material mixed dichlorobenzene (o - dichlorobenzene:p - dichlorobenzene:m - dichlorobenzene = 3:3:4) enters the adsorption tower through the inlet - outlet pipe 321. The adsorption temperature is 180 °C, and the adsorption pressure is 1.0 MPa; during desorption, the adsorption tower is filled with the desorbent chlorobenzene, the desorption temperature is 200 °C, and the desorption pressure is 0.6 MPa.

[0079] The collected raffinate is ortho-dichlorobenzene and para-dichlorobenzene, with a weight of 30.7 kg; the collected desorbent is meta-dichlorobenzene, with a purity of 99.73% and a weight of 19.3 kg. The calculated recovery rate of meta-dichlorobenzene is 96.5%.

[0080] Example 6 Use the adsorption tower equipment described in Example 2 to prepare p-xylene. The diameter of the adsorption tower is 3.5 meters, and it is filled with 12 layers of adsorbents. The height of each adsorbent bed layer is 550 mm; the adsorbent is 13X molecular sieve modified with potassium nitrate and lithium hydroxide. The mixing-distribution internal component is divided into 12 equal-area blocks. The orifice plate of the inlet and outlet conical distribution chambers of the middle mixing-distributor has 3 rows of holes, with a hole diameter of 10.0 mm and a hole pitch of 50 mm. The calculated hole flow velocity is 3.0 - 8.0 m / s. The flow velocity of the mixing channel designed in the conical mixing chamber of the middle mixing-distributor is 1.8 m / s, and the flow velocity at the outlet of the conical mixing chamber is 1.1 m / s. The baffle of the conical discharge chamber has 3 rows of holes, with a hole diameter of 3.0 mm at the tip of the cone, 12.0 mm at the tail of the cone, and 6.0 mm in the middle.

[0081] 50 kg of raw material mixed xylene (ortho-xylene: p-xylene: meta-xylene = 3.5:2.5:4) enters the adsorption tower through the inlet and outlet pipe 321. The adsorption temperature is 175 °C, and the adsorption pressure is 0.8 MPa; during desorption, the adsorption tower is filled with desorbent toluene, the desorption temperature is 180 °C, and the desorption pressure is 0.6 MPa.

[0082] The collected raffinate is ortho-xylene and meta-xylene, with a weight of 37.9 kg; the collected desorbent is p-xylene, with a purity of 99.8% and a weight of 12.0 kg. The calculated recovery rate of p-xylene is 96.0%.

[0083] In the present invention, there is no static area at the top or bottom of the internal component, which can ensure the full flow of the fluid; at the same time, different hole flow velocity designs are adopted to ensure that the fluid in the adsorption tower is fully mixed and uniform with the inlet and outlet fluids, without backmixing and uneven flow. In addition, the present invention adopts a liquid-phase adsorption process, avoiding the equipment investment and energy consumption required for fluid gasification and condensation, and greatly reducing the production cost. Using the adsorption tower equipment of the present invention, meta-dichlorobenzene products with a purity greater than 99.5% and a yield greater than 95% can be obtained. The adsorption tower equipment of the present invention can also be applied to the production of high-purity p-xylene.

[0084] The above description of the embodiments is to enable those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative efforts. Therefore, the present invention is not limited to the above embodiments, and all improvements and modifications made by those skilled in the art without departing from the scope of the present invention according to the disclosure of the present invention should be within the protection scope of the present invention.

Claims

1. A liquid-phase adsorption separation system, characterized in that, It includes an adsorption tower body (1) and three or more adsorbent beds (2) arranged inside the adsorption tower body (1), and a mixing-distribution internal member (3) is provided between two adjacent adsorbent beds (2); The mixing-distribution internal member (3) includes an upper support grid (31), an intermediate mixing-distributor (32) and a lower support grid (33); The intermediate mixing-distributor (32) includes a feed and discharge pipe (321), a feed and discharge conical distribution chamber (322), a conical mixing chamber (323) and a conical discharge chamber (324). The feed and discharge conical distribution chamber (322), the conical mixing chamber (323) and the conical discharge chamber (324) are all arranged between the upper support grid (31) and the lower support grid (33); The feed and discharge pipe (321) passes through the upper support grid (31) and the adsorption tower body (1) and communicates with the outside. The feed and discharge conical distribution chamber (322) is communicated with the feed and discharge pipe (321). The conical mixing chamber (323) is arranged below the feed and discharge conical distribution chamber (322) and is communicated with the feed and discharge conical distribution chamber (322). The conical discharge chamber (324) is arranged below the conical mixing chamber (323) and is communicated with the conical mixing chamber (323); The feed and discharge conical distribution chamber (322) includes two perforated plates (3222). Each perforated plate (3222) has 3-6 rows of holes, and the hole diameter is 2-25 mm; The conical discharge chamber (324) includes two inclined conical discharge chamber baffles (3241). The two conical discharge chamber baffles (3241) have 3-6 rows of holes. The hole diameter of the opening gradually increases from the cone tip to the cone tail. The hole diameter of the opening near the cone tip is 2-5 mm, the hole diameter of the opening near the cone tail is 10-15 mm, and the hole diameter of the opening in the middle is 5-10 mm.

2. The liquid-phase adsorption separation system according to claim 1, wherein The feed and discharge conical distribution chamber (322) includes a half pipe (3221) and two perforated plates (3222); The two perforated plates (3222) form a conical structure. The cone angle of the conical structure is 30°-60°. The half pipe (3221) is arranged at the top of the conical structure and is communicated with the feed and discharge pipe (321); The hole spacing of each perforated plate (3222) is 4-15 times the hole diameter, and the hole flow velocity of the opening is 3.0-10.0 m / s.

3. The liquid-phase adsorption separation system according to claim 1, wherein The conical mixing chamber (323) includes two conical mixing chamber partitions (3231) and two inclined conical mixing chamber baffles (3232); One end of the conical mixing chamber partition (3231) is fixed, and the other end is connected to the conical mixing chamber baffle (3232). A mixing channel (3233) is formed between the conical mixing chamber baffle (3232) and the feed and discharge conical distribution chamber (322). The flow velocity of the mixing channel is 1.5-3.5 m / s. A conical mixing chamber outlet (3234) is formed between the bottoms of the two conical mixing chamber baffles (3232). The flow velocity of the conical mixing chamber outlet (3234) is 0.5-1.5 m / s.

4. The liquid-phase adsorption separation system according to claim 1, wherein An outlet channel (3242) is formed between the conical outlet chamber baffle (3241) of the conical outlet chamber (324) and the conical mixing chamber (323), and the outlet flow rate of the outlet channel (3242) is 0.1 - 0.5 m / s; The flow rate of the openings at the conical tails of the two conical outlet chamber baffles (3241) is 0.1 - 0.5 m / s, the flow rate of the openings at the conical tips is 0.5 - 1.0 m / s, and the flow rate of the openings in the middle is between the former two.

5. The liquid-phase adsorption separation system according to claim 1, wherein The mixing - distribution internal member (3) is divided into 2 - 20 sub - internal members with equal areas. Each pair of sub - internal members is isolated by a partition plate (4), and each sub - internal member is provided with an intermediate mixing - distributor (32); The adsorbent bed layer (2) has 3 - 20 layers, and the adsorbent bed layer (2) is filled with an adsorbent.

6. Use of the liquid-phase adsorption separation system according to any one of claims 1 to 5, characterized in that, Using the liquid - phase adsorption separation system for producing high - purity m - dichlorobenzene includes the following steps: Fresh feed enters the inlet - outlet conical distribution chamber (322) from the first - layer inlet - outlet pipe (321), and then flows into the mixing channel (3233) from the perforated plate (3222) of the inlet - outlet conical distribution chamber (322). The circulating material in the adsorption tower body (1) passes through different adsorbent bed layers (2) and the mixing - distribution internal member (3) from top to bottom, and then is blocked by the conical mixing chamber baffle (3232) and can only enter the mixing channel (3233) of the conical mixing chamber (323), where it is completely mixed evenly with the fresh feed. The evenly - mixed fluid flows out through the conical mixing chamber outlet (3234) and enters the conical outlet chamber (324), and the fluid flows out through the openings of the conical outlet chamber baffle (3241) and the outlet channel (3242); Both the fresh feed and the circulating material contain o - dichlorobenzene, p - dichlorobenzene, and m - dichlorobenzene; Both the fresh feed and the circulating material are adsorbed by at least N layers of the adsorbent bed layer (2), and the raffinate after adsorption is withdrawn from the inlet - outlet pipe (321) of the (N + 1) - th layer; The N is not less than 3.

7. Use of the liquid-phase adsorption separation system according to claim 6, characterized in that, A circulating pipeline and a circulating pump are provided outside the adsorption tower body (1). The circulating pipeline and the circulating pump circulate the fluid flowing out from the bottom head of the adsorption tower body (1) to the upper part as circulating material.

8. The application of the liquid-phase adsorption separation system according to claim 6, characterized in that, The adsorbent filled in the adsorbent bed layer (2) is an adsorbent for adsorbing o - dichlorobenzene and p - dichlorobenzene or an adsorbent for adsorbing m - dichlorobenzene. The adsorption temperature is 150 - 250 °C, and the adsorption pressure is 0.5 - 1.5 MPa.

9. Use of the liquid-phase adsorption separation system according to claim 8, characterized in that, The adsorbent is an X - type molecular sieve, Y - type molecular sieve, ZSM series molecular sieve, or SAPO series molecular sieve modified with a Group IA or Group IIA metal.

10. The application of the liquid-phase adsorption separation system according to claim 6, characterized in that, It also includes the following steps: After 50 s - 250 s of starting the fresh feed, the fresh feed is stopped, and the desorbent enters the inlet - outlet conical distribution chamber (322) from the first - layer inlet - outlet pipe (321), and then desorbs the o - dichlorobenzene, p - dichlorobenzene, or m - dichlorobenzene adsorbed in the adsorbent along the same channel as the fresh feed; The desorbent is chlorobenzene, dichlorotoluene, xylene, or a mixture thereof; The desorption temperature is 150 - 250 °C, and the desorption pressure is 0.5 - 1.5 MPa; The desorbed desorbate is withdrawn from the inlet - outlet pipe (321) of the (N + 1) - th layer; The N is not less than 3.

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