A high purity diphenyl carbonate separation apparatus, separation method, and system

Abstract

The application discloses a high-purity diphenyl carbonate separation device, a separation method and a system, wherein a first reboiler of a first refining separation unit is communicated with a bottom of a first refining packed tower to form a heating loop; the first refining packed tower, an air condenser and a first gas-liquid separator are sequentially communicated; a first vent condenser is respectively communicated with the air condenser and the first gas-liquid separator and externally connected with a vacuum device; the first gas-liquid separator is externally connected with a diphenyl carbonate preparation device; a second refining packed tower of a second refining separation unit is communicated with the first refining packed tower, a second reboiler is communicated with a bottom of the second refining packed tower to form a heating loop; the second refining packed tower, an evaporative condenser and a second gas-liquid separator are sequentially communicated; a second vent condenser is respectively communicated with the evaporative condenser and the second gas-liquid separator and externally connected with a vacuum device; a product storage unit is communicated with the second gas-liquid separator, and the device separates high-purity DPC by adopting a vacuum operation and two-tower continuous rectification.

Description

Technical Field

[0001] This invention relates to the field of industrial-scale high-purity diphenyl carbonate preparation technology, and particularly to a high-purity diphenyl carbonate separation device, separation method and system. Background Technology

[0002] Diphenyl carbonate (DPC) is an important chemical intermediate. It is a non-toxic, non-polluting, and non-corrosive green chemical product that can be used to synthesize many organic compounds and polymer materials, such as monoisocyanates, diisocyanates, poly(p-hydroxybenzoates), and polyaryl carbonates. It can also be used as a plasticizer for polyamides and polyesters, a high-boiling-point organic solvent, and a heat transfer medium. In particular, it can replace highly toxic phosgene in the reaction with bisphenol A to produce high-performance polycarbonates.

[0003] Currently, there are three main methods for synthesizing DPC: phosgenation, oxidative carbonylation, and transesterification. The traditional method uses phosgene and phenol as raw materials, reacting them in an alkaline medium. However, phosgene is highly toxic and corrosive, posing significant safety and environmental problems. Furthermore, residual chloride ions remain in the resulting DPC, affecting the quality of the polycarbonate obtained from the reaction of diphenyl carbonate and bisphenol A. Therefore, non-phosgene methods for DPC synthesis have become a research focus. Currently, oxidative carbonylation and transesterification are the main non-phosgene synthesis methods. Oxidative carbonylation is unsuitable for large-scale industrial production due to the high cost and low yield of the precious metal Pd catalyst. Therefore, the transesterification reaction of phenol and dimethyl carbonate under a catalyst is the only industrially viable non-phosgene synthesis route.

[0004] There are two process routes to choose from for transesterification. One is a one-step method, in which dimethyl carbonate and phenol are directly synthesized through transesterification in a reactor. The products include diphenyl carbonate, methyl phenyl carbonate, and anisole, which are then further separated to obtain diphenyl carbonate. The other method is a two-step method, in which dimethyl carbonate and phenol are first transesterified to obtain the intermediate methyl phenyl carbonate, which is then separated and subjected to disproportionation reaction alone or transesterified with phenol again to obtain diphenyl carbonate.

[0005] For the two-step reaction, after the second step, the DPC product at the bottom of the synthesis tower is typically purified by double-tower distillation after deweighting and catalyst recovery to separate the DPC and MPC mixture, ultimately yielding a high-purity DPC product. In the two-step reaction using a homogeneous catalyst, the transesterification reaction of the diphenyl carbonate reaction usually produces byproducts, especially high-boiling-point byproducts such as phenyl salicylate, phenyl methoxybenzoate, and xanthones, which can affect the purity of the diphenyl carbonate product. Therefore, how to prepare high-purity diphenyl carbonate under industrial-scale conditions to obtain high-quality, high-performance polycarbonate is currently a key focus. Summary of the Invention

[0006] In order to improve the industrial purity of diphenyl carbonate and to effectively recover and utilize heat, this invention provides a high-purity diphenyl carbonate separation device, separation method and system.

[0007] In a first aspect, embodiments of the present invention provide a high-purity diphenyl carbonate separation device, which may include: a first refining and separation unit, a second refining and separation unit, and a product storage unit;

[0008] The first refining and separation unit may include: a first refining packed tower, a first reboiler, an air condenser, a first gas-liquid separator, and a first venting condenser; the first reboiler is connected to the bottom of the first refining packed tower to form a heating circuit; the top of the first refining packed tower, the air condenser, and the first gas-liquid separator are sequentially connected to form a circuit; the first venting condenser is connected to both the air condenser and the first gas-liquid separator, and is externally connected to a vacuum device; the first gas-liquid separator is externally connected to a diphenyl carbonate preparation device;

[0009] The second refining and separation unit may include: a second refining packed tower, a second reboiler, an evaporative condenser, a second gas-liquid separator, and a second venting condenser; the bottom of the first refining packed tower is connected to the second refining packed tower, and the second reboiler is connected to the bottom of the second refining packed tower to form a heating circuit; the top of the second refining packed tower, the evaporative condenser, and the second gas-liquid separator are sequentially connected to form a circuit; the second venting condenser is connected to the evaporative condenser and the second gas-liquid separator respectively, and is externally connected to a vacuum device;

[0010] The product storage unit is connected to the second gas-liquid separator.

[0011] In one embodiment, the inner diameter of the first refined packed tower is 2000~3800mm and the tower height is 28000mm. The packing of the first refined packed tower consists of two layers with a packing height of 7000mm.

[0012] The second refining packed tower has an inner diameter of 1000~3700mm and a tower height of 23400mm. The packing of the second refining packed tower consists of two layers with a packing height of 6000mm.

[0013] In another embodiment, the first refining packed tower is filled with corrugated plates, and / or the second refining packed tower is filled with corrugated plates.

[0014] In another embodiment, the first refining and separation unit may further include: a first separation pump, the inlet of which is connected to the bottom of the first refining packed tower, and the outlet of which is connected to the inlet of the first reboiler and the second refining packed tower, respectively.

[0015] The second refining and separation unit may further include: a second separation pump, the inlet of which is connected to the bottom of the second refining packed tower, and the outlet of which is connected to the inlet of the second reboiler.

[0016] In another embodiment, the first refining and separation unit may further include: a third separation pump, the inlet of which is connected to the first gas-liquid separator, and the outlet of which is connected to the first refining packed tower and an external diphenyl carbonate preparation device, respectively.

[0017] The second refining and separation unit may further include: a fourth separation pump, the inlet of which is connected to the second gas-liquid separator, and the outlet of which is connected to the second refining packed tower and the product storage unit respectively.

[0018] In another embodiment, the product storage unit may include: a product storage tank and a fifth centrifugal pump;

[0019] The product storage tank is connected to the second gas-liquid separator; the fifth centrifugal pump is connected to the product storage tank.

[0020] In a second aspect, embodiments of the present invention provide a method for separating high-purity diphenyl carbonate, wherein the separation is performed using the high-purity diphenyl carbonate separation apparatus described in the first aspect, and may include:

[0021] The feed is continuously fed into the first refined packed tower in the first refined separation unit at a rate of 20.8 tons / hr or more. The temperature and pressure parameters of the first refined packed tower and the reflux ratio of the first gas-liquid separator in the first refined separation unit are controlled to continuously distill diphenyl carbonate. The top pressure of the first refined packed tower is 1470~2000 PaA, the top temperature is 94~103℃, the bottom temperature is 187~197℃, and the reflux ratio is 3.5:1~3.73:1.

[0022] The material after distillation in the first refining and separation unit is fed into the second refining and separation unit. The temperature and pressure parameters of the second refining packed column and the reflux ratio of the second gas-liquid separator in the second refining and separation unit are controlled to continuously distill diphenyl carbonate. The top pressure of the second refining packed column is 892~2080 PaA, the top temperature is 160~180℃, the bottom temperature is 191~200℃, and the reflux ratio is 0.52:1~0.6:1.

[0023] The diphenyl carbonate obtained after distillation in the second refining and separation unit is sent to the product storage unit.

[0024] Thirdly, embodiments of the present invention provide a diphenyl carbonate preparation system, which may include: a diphenyl carbonate preparation apparatus, a vacuum apparatus, and a high-purity diphenyl carbonate separation apparatus as described in the first aspect;

[0025] The diphenyl carbonate preparation device is connected to the inlet of the first refining packed tower and the outlet of the first gas-liquid separator, respectively. The diphenyl carbonate preparation device is used to prepare diphenyl carbonate and send the prepared diphenyl carbonate into the first refining packed tower for separation and purification by the high-purity diphenyl carbonate separation device.

[0026] The vacuum device is connected to the vent port of the first vent condenser and the vent port of the second vent condenser, respectively, and is used to extract the gas from the first vent condenser and the second vent condenser.

[0027] In another embodiment, the diphenyl carbonate preparation apparatus may include: a methyl phenyl carbonate synthesis unit, a methyl phenyl carbonate purification unit, and a diphenyl carbonate synthesis unit;

[0028] The methyl phenyl carbonate synthesis unit may include: a first reactive distillation column, a first condenser, and a third reboiler; the first reactive distillation column is used to synthesize methyl phenyl carbonate, the first condenser is connected to the top of the first reactive distillation column, and the third reboiler is connected to the bottom of the first reactive distillation column;

[0029] The methyl phenyl carbonate purification unit may include: a methyl phenyl carbonate concentration tower, a second condenser, a fourth reboiler, and an anisole recovery tower; the methyl phenyl carbonate concentration tower is connected to the bottom of the first condenser and the first reactive distillation tower, respectively, for concentrating methyl phenyl carbonate; the second condenser is connected to the top of the methyl phenyl carbonate concentration tower; the fourth reboiler is connected to the bottom of the methyl phenyl carbonate concentration tower; and the anisole recovery tower is connected to the middle of the methyl phenyl carbonate concentration tower.

[0030] The diphenyl carbonate synthesis unit may include: a second reactive distillation column, a third condenser, and a fifth reboiler. The second reactive distillation column is connected to the bottom of the methyl phenyl carbonate concentration column and is used to synthesize diphenyl carbonate. The third condenser is connected to the top of the second reactive distillation column. The fifth reboiler is connected to the bottom of the second reactive distillation column.

[0031] In another embodiment, the feed rate of the first refining packed tower is not less than 20.8 tons / hr; the top pressure of the first refining packed tower is 1470~2000 PaA, the top temperature is 94~103℃, the bottom temperature is 187~197℃; and the reflux ratio is 3.5:1~3.73:1.

[0032] The second refining packed tower has a top pressure of 892~2080 PaA, a top temperature of 160~180℃, a bottom temperature of 191~200℃, and a reflux ratio of 0.52:1~0.6:1.

[0033] The beneficial effects of the above-mentioned technical solutions provided in the embodiments of the present invention include at least the following:

[0034] This invention provides a high-purity diphenyl carbonate separation device, method, and system. The separation device uses reduced pressure operation and two-tower continuous distillation to separate high-purity DPC. Compared with the prior art, it can achieve industrial-scale production and separate diphenyl carbonate products with a purity higher than 99.99% under continuous and stable operation conditions.

[0035] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description and the accompanying drawings.

[0036] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0037] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0038] Figure 1 This is a process structure diagram of the high-purity diphenyl carbonate separation device provided in the embodiments of the present invention;

[0039] Figure 2 This is a process structure diagram of the diphenyl carbonate preparation apparatus provided in the embodiments of the present invention;

[0040] Among them, 1-high-purity diphenyl carbonate separation device; 2-vacuum device; 3-diphenyl carbonate preparation device;

[0041] 11-First refining and separation unit; 12-Second refining and separation unit; 13-Product storage unit; 31-Methylphenyl carbonate synthesis unit; 32-Methylphenyl carbonate purification unit; 33-Diphenyl carbonate synthesis unit;

[0042] 111-First refining packed tower; 112-First reboiler; 113-Air condenser; 114-First gas-liquid separator; 115-First venting condenser; 116-First separation pump; 117-Third separation pump;

[0043] 121-Second refining packed tower; 122-Second reboiler; 123-Evaporative condenser; 124-Second gas-liquid separator; 125-Second venting condenser; 126-Second separation pump; 127-Fourth separation pump;

[0044] 131 - Product storage tank; 132 - Fifth centrifugal pump;

[0045] 311-First reactive distillation column; 312-First condenser; 313-Third reboiler; 321-Methylphenyl carbonate concentration column; 322-Second condenser; 323-Fourth reboiler; 324-Anisole recovery column; 325-Sixth reboiler; 331-Second reactive distillation column; 332-Third condenser; 333-Fifth reboiler. Detailed Implementation

[0046] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0047] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," "outer," "far," "near," "front," and "rear," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0048] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0049] Patent CN101010284A discloses an industrial method for preparing high-purity diphenyl carbonate (DPC). This method uses a two-tower distillation process to feed a reaction mixture containing DPC into a high-boiling-point separation tower A at an industrial scale of over 1 ton per hour. The top component containing DPC and the bottom component containing the catalyst are continuously separated by distillation. The top component from tower A is then fed into a refining tower with a side fraction outlet, where the top, side, and bottom components are continuously separated by distillation. This method can stably produce high-purity DPC over a long period. However, the patent document discloses a DPC purity of only 99.9% or higher. Furthermore, the inventors found that the patent does not effectively recover and utilize heat, resulting in energy waste.

[0050] Patent CN204625511U discloses a vacuum distillation apparatus for purifying diphenyl carbonate (DPC). Crude DPC enters from the upper part of a vacuum distillation tower. After vacuum distillation, the DPC-containing stream at the top of the tower is condensed by a condenser and enters a gas-liquid separator. The non-condensable gases are condensed by a venting condenser. The condensed liquid portion returns to the gas-liquid separator, while the gaseous portion is drawn into a vacuum buffer tank by a vacuum system. High-purity DPC is discharged to a DPC product buffer tank, and the remaining portion is returned to the vacuum distillation tower as reflux. The portion containing the catalyst at the bottom of the vacuum distillation tower is pumped to a residue tank. Although this patent improves the purity of the DPC product through vacuum operation, the inventors found that the patent does not specifically describe the purity of the DPC product, nor does it specify whether it can be achieved on an industrial scale, and the process does not further recover and utilize heat.

[0051] Patent CN101044109A discloses an industrial method for preparing high-purity diaryl carbonate (DPC). This method involves using a reactive distillation column to perform a transesterification reaction on the raw materials. The high-boiling-point reaction mixture obtained from the bottom of the column is then sequentially processed using a high-boiling-point substance separation column A (composed of three specific continuous multi-stage distillation columns), a diaryl carbonate purification column B, and a medium-boiling-point substance separation column C. This process is used to stably produce high-purity DPC as a component of the side fraction of purification column B at an industrial scale of at least 1 ton per hour over a long period. The inventors found that this patent does not specifically specify the purity of the DPC product and employs a three-column separation process, which is complex and has relatively high energy consumption.

[0052] Patent CN104086421A discloses a method for producing diphenyl carbonate (DPC) using a fixed-bed reactor and a distillation column. Dimethyl carbonate and phenol are used as raw materials, reacting on a catalyst in a fixed bed to produce methylphenyl carbonate and diphenyl carbonate. The reaction is then coupled into a distillation column to separate and produce DPC. The apparatus includes a fixed-bed reaction unit, a distillation unit, a purification unit, and a vacuum system. The DPC purification unit employs reduced-pressure fractionation, with continuous fractionation in two columns to separate the DPC product. However, this patent does not specify the purity of the DPC product, and the process does not further recover and utilize heat.

[0053] The inventors discovered in their research that, in the DPC refining process, reduced-pressure vacuum operation, an appropriate number of distillation columns, and specific column parameters are crucial for obtaining high-purity DPC products. High-purity DPC raw materials are also key to preparing high-quality, high-performance polycarbonate. Although a process for long-term stable production of DPC products at an industrial scale of 1 ton / hr has been achieved, the design of higher-scale, high-purity DPC separation units is urgently needed due to the continuous expansion of the product market and the increasing scale of individual equipment. Furthermore, designing a low-energy-consumption continuous distillation unit by controlling operating parameters and optimizing the heat exchange network is also a current research hotspot. In view of the above problems, this invention is proposed to provide a high-purity diphenyl carbonate separation device, method, and system that overcomes or at least partially solves the aforementioned problems.

[0054] This invention provides a high-purity diphenyl carbonate separation device, referring to... Figure 1As shown, the high-purity diphenyl carbonate separation device 1 may include: a first refining separation unit 11, a second refining separation unit 12, and a product storage unit 13; wherein, the first refining separation unit 11 may include: a first refining packed tower 111, a first reboiler 112, an air condenser 113, a first gas-liquid separator 114, and a first venting condenser 115; the first reboiler 112 is connected to the bottom of the first refining packed tower 111 to form a heating circuit; the top of the first refining packed tower 111, the air condenser 113, and the first gas-liquid separator 114 are sequentially connected to form a circuit; the first venting condenser 115 is connected to the air condenser 113 and the first gas-liquid separator 114 respectively, and is externally connected to a vacuum device 2; the first gas-liquid separator 111... 4. External diphenyl carbonate preparation device 3; The second refining and separation unit 12 may include: a second refining packed tower 121, a second reboiler 122, an evaporative condenser 123, a second gas-liquid separator 124, and a second venting condenser 125; The bottom of the first refining packed tower 111 is connected to the second refining packed tower 121, and the second reboiler 122 is connected to the bottom of the second refining packed tower 121 to form a heating circuit; The top of the second refining packed tower 121, the evaporative condenser 123, and the second gas-liquid separator 124 are sequentially connected to form a circuit; The second venting condenser 125 is connected to the evaporative condenser 123 and the second gas-liquid separator 124 respectively, and is externally connected to a vacuum device 2; The product storage unit 13 is connected to the second gas-liquid separator 124.

[0055] In this embodiment of the invention, the purified and separated material is prepared by a diphenyl carbonate preparation device. It comprises diphenyl carbonate (DPC), methyl phenyl carbonate (MPC), and fresh phenol (PHF). In this embodiment, the material comprises 68% DPC, 28% MPC, and 4% PHF by mass percentage. (Refer to...) Figure 1 As shown, the above-mentioned material is supplied by the diphenyl carbonate preparation device 3 and directly fed into the first refining packed tower 111 of the first refining separation unit 11 of the high-purity diphenyl carbonate separation device 1. Combined with... Figure 2 As shown, in this embodiment of the invention, the unseparated DPC is produced by first reacting dimethyl carbonate (DMC) and phenol (PHF) via transesterification in the presence of a homogeneous catalyst to generate methyl phenyl carbonate (MPC), and then MPC undergoes disproportionation and transesterification to yield a mixture containing diphenyl carbonate. (Refer to...) Figure 2 As shown, after the DPC synthesis reaction in the second reactive distillation column 331, the bottom product is separated into gas and liquid by a DPC flash tank. The catalyst is collected from the bottom of the DPC flash tank and recovered by a scraped film evaporator. The remaining components (including DPC, MPC and phenol) enter the separation device in this embodiment of the invention.

[0056] The working process and working principle of the high-purity diphenyl carbonate separation device in this embodiment of the invention are as follows: The material is first fed into the first refining packed tower 111 (i.e., DPC refining tower) for distillation and separation. This tower operates under negative pressure. The gas phase at the top of the tower is a mixture of recovered MPC and phenol. After being condensed by the top condenser (air condenser 113) and the exhaust condenser (first vent condenser 115), part of it is refluxed and part is collected and sent back to the two-step reaction tower (second reactive distillation tower 331) of the diphenyl carbonate preparation device 3. The mixture of DPC and heavy components at the bottom of the first refining packed tower 111 is fed into the second refining packed tower 121. The heavy components at the bottom of the tower are sent into the heavy component discharge tank of the diphenyl carbonate preparation device 3. The high-purity DPC gas phase product is obtained by distillation at the top of the tower. The product is condensed by the top condenser (evaporative condenser 123) and the exhaust condenser (second vent condenser 125), and steam is produced as a by-product at the same time.

[0057] The high-purity diphenyl carbonate separation device provided in this embodiment of the invention employs reduced pressure operation and continuous distillation in two columns to separate high-purity DPC. Compared with existing technologies, it can achieve industrial-scale production and separate diphenyl carbonate products with a purity higher than 99.99% under continuous and stable operation. Furthermore, the use of an evaporative condenser saves energy, generating 3.2~3.4 tons / hr of steam at 0.16 MPaG, thus improving resource recovery efficiency.

[0058] In an optional embodiment, the first refining packed column 111 has an inner diameter of 2000-3800 mm and a height of 28000 mm, with two layers of packing material and a packing height of 7000 mm. The second refining packed column 121 has an inner diameter of 1000-3700 mm and a height of 23400 mm, with two layers of packing material and a packing height of 6000 mm. Specifically, the packing material of the first refining packed column 111 is corrugated plate, and / or the packing material of the second refining packed column 121 is corrugated plate. In this embodiment of the invention, the first and second refining packed columns can maintain continuous distillation for a long time, ensuring the yield and purity of diphenyl carbonate.

[0059] In another alternative embodiment, refer to Figure 1As shown, the first refining and separation unit 11 may further include: a first separation pump 116, the inlet of which is connected to the bottom of the first refining packed tower 111, and the outlet of which is connected to the inlet of the first reboiler 112 and the second refining packed tower 121 respectively; the second refining and separation unit 12 may further include: a second separation pump 126, the inlet of which is connected to the bottom of the second refining packed tower 121, and the outlet of which is connected to the inlet of the second reboiler 122. In this embodiment of the invention, the first and second separation pumps provide the power for the thermal cycle, enabling continuous heating of the first and second reboilers respectively.

[0060] In another alternative embodiment, refer to Figure 1 As shown, the first refining and separation unit 11 may further include: a third separation pump 117, the inlet of which is connected to the first gas-liquid separator 114, and the outlet of which is connected to the first refining packed tower 111 and the external diphenyl carbonate preparation device 3; the second refining and separation unit 12 may further include: a fourth separation pump 127, the inlet of which is connected to the second gas-liquid separator 124, and the outlet of which is connected to the second refining packed tower 121 and the product storage unit 13. In this embodiment, the third and fourth separation pumps provide power for reflux distillation to ensure the efficient operation of the entire separation unit.

[0061] In another alternative embodiment, refer to Figure 1 As shown, the product storage unit 13 may include: a product storage tank 131 and a fifth centrifugal pump 132; the product storage tank 131 is connected to the second gas-liquid separator 124; the fifth centrifugal pump 132 is connected to the product storage tank 131. The product storage unit in this embodiment of the invention can store the separated high-purity diphenyl carbonate and pump it into downstream processes.

[0062] Based on the same inventive concept, this embodiment of the invention also provides a method for separating high-purity diphenyl carbonate. This method involves separation using the aforementioned high-purity diphenyl carbonate separation device 1, with reference to... Figure 2 As shown, the following steps may be included:

[0063] Step S21: The feed is continuously fed into the first refining packed tower 111 in the first refining separation unit 11 at a feed rate of 20.8 tons / hr or more. The temperature and pressure parameters of the first refining packed tower 111 and the reflux ratio of the first gas-liquid separator 114 in the first refining separation unit 11 are controlled to continuously distill diphenyl carbonate. The top pressure of the first refining packed tower 111 is 1470~2000 PaA, the top temperature is 94~103℃, the bottom temperature is 187~197℃, and the reflux ratio is 3.5:1~3.73:1.

[0064] Step S22: The material after distillation in the first refining and separation unit 11 is fed into the second refining and separation unit 12. The temperature and pressure parameters of the second refining packed tower 121 and the reflux ratio of the second gas-liquid separator 124 in the second refining and separation unit 12 are controlled to continuously distill diphenyl carbonate. The top pressure of the second refining packed tower 121 is 892~2080 PaA, the top temperature is 160~180℃, the bottom temperature is 191~200℃, and the reflux ratio is 0.52:1~0.6:1.

[0065] Step S23: The diphenyl carbonate obtained after distillation in the second refining and separation unit 12 is sent to the product storage unit 13.

[0066] Based on the same inventive concept, this invention also provides a diphenyl carbonate preparation system, referring to... Figure 1 As shown, the system may include: a diphenyl carbonate preparation device 3, a vacuum device 2, and the aforementioned high-purity diphenyl carbonate separation device 1; wherein, the diphenyl carbonate preparation device 3 is connected to the inlet of the first refining packed tower 111 and the outlet of the first gas-liquid separator 114 respectively; the diphenyl carbonate preparation device 3 is used to prepare diphenyl carbonate and send the prepared diphenyl carbonate into the first refining packed tower 111 for separation and purification by the high-purity diphenyl carbonate separation device 1; the vacuum device 2 is connected to the vent port of the first vent condenser 115 and the vent port of the second vent condenser 125 respectively, and the vacuum device 2 is used to extract the gas in the first vent condenser 115 and the second vent condenser 125 respectively.

[0067] In another optional embodiment, the feed rate of the first refining packed tower 111 is not less than 20.8 tons / hr; the top pressure of the first refining packed tower 111 is 1470~2000 PaA, the top temperature is 94~103℃, the bottom temperature is 187~197℃, and the reflux ratio is 3.5:1~3.73:1; the top pressure of the second refining packed tower 121 is 892~2080 PaA, the top temperature is 160~180℃, the bottom temperature is 191~200℃, and the reflux ratio is 0.52:1~0.6:1.

[0068] The following are specific embodiments provided in this invention, wherein the raw materials involved are all commercially available and commonly used raw materials, and this invention does not impose any specific limitations on them. Example 1

[0069] In Embodiment 1 of the present invention, the inner diameter of the first refined packed tower 111 is 3800mm at the top and 2200mm at the bottom, the tower height (tangent) is 28000mm, the tower has two layers of packing with a height of 7000mm, and the packing is corrugated plate; the inner diameter of the second refined packed tower 121 is 3700mm at the top and 1100mm at the bottom, the tower height (tangent) is 23400mm, the tower has two layers of packing with a height of 6000mm, and the packing is corrugated plate.

[0070] A material containing DPC, MPC, and fresh phenol (wt%: DPC 68%, MPC 28%, PHF 4%) is continuously fed into the first refining packed column 111 at a rate of 25.4 tons / hr. During the distillation process, the bottom temperature (TA) of the first refining packed column 111 is 191°C, the top temperature (TB) is 102°C, and the top pressure (PA) is 2000 PaA. The distillation is carried out continuously at a reflux ratio of 3.64, and the top extraction rate is 37.3 tons / hr. The gaseous stream from the top of the column is condensed by the air condenser 113 and enters the first gas-liquid separator 114. The non-condensable gas is condensed by the first vent condenser 115. The condensed liquid portion is returned to the first gas-liquid separator 114, and the gaseous portion (wt%: DMC 43.2%, AIR 24.9%, MPC 22.9%, PHF 9%) is drawn in by the vacuum device 2. The material in the first gas-liquid separator 114 is partially refluxed (wt%: MPC 87.4%, PHF 11.5%, others 1.1%) to the first refining packed tower 111, and partially continuously collected and sent to the diphenyl carbonate preparation unit 3. The bottom components are continuously extracted at a flow rate of 19.0 tons / hr.

[0071] The material drawn from the bottom of the first refining packed column 111 directly enters the second refining packed column 121. During the distillation process, the bottom temperature (TB) of the second refining packed column 121 is 191℃, the top temperature (TB) is 168℃, and the top pressure (PB) is 1300PaA. Continuous distillation is carried out with a reflux ratio of 0.6. The top extraction rate is 30 tons / hr. The high-purity DPC material in the gas phase at the top of the column is condensed by the evaporative condenser 123, and 0.16MPaG of vapor is generated at the same time. The non-condensable gas is condensed by the second vent condenser 125. The liquid part after condensation is returned to the second gas-liquid separator 125, and the gas part (wt%: AIR 87.8%, DPC 12.2%) is drawn into the vacuum buffer tank by the vacuum device 2. The liquid material in the second gas-liquid separator 124 is partially returned to the second refining packed tower 121, and partially continuously extracted into the product storage tank 131 at a rate of 18.7 tons / hr. The heavy components at the bottom of the tower are continuously extracted at a rate of 0.25 tons / hr.

[0072] Implementation effect

[0073] The extracted product contains less than 0.01% total impurities (including but not limited to phenyl salicylate, phenyl methoxybenzoate, and xanthones), and the purity of diphenyl carbonate is above 99.99%. Under these conditions, the evaporative condenser 123 generates 3.4 tons of steam per hr at a rate of 0.16 MPaG, saving 11.5 kgoe / ton (of product) in energy consumption. Under these conditions, the separation unit can operate continuously for over 8000 hours at an industrial scale of 130,000 tons / year, with virtually no change in the production volume and purity of diphenyl carbonate. Example 2

[0074] In Embodiment 2 of the present invention, the first refining packed tower 111 has an inner diameter of 3500 mm at the top and 2000 mm at the bottom, and a tower height (tangential) of 28000 mm. It contains two layers of packing with a height of 7000 mm, and the packing is corrugated plate. The second refining packed tower 121 has an inner diameter of 3400 mm at the top and 1000 mm at the bottom, and a tower height (tangential) of 23400 mm. It also contains two layers of packing with a height of 6000 mm, and the packing is corrugated plate.

[0075] A material containing DPC, MPC, and fresh phenol (wt%: DPC 68%, MPC 28%, PHF 4%) is continuously fed into the first refining packed column 111 at a rate of 20.8 tons / hr. During the distillation process, the bottom temperature (TA) of the first refining packed column 111 is 197°C, the top temperature (TB) is 103°C, and the top pressure (PA) is 2678 PaA. The distillation is carried out continuously at a reflux ratio of 3.5, and the top extraction rate is 27.8 tons / hr. The gaseous stream from the top of the column is condensed by the air condenser 113 and enters the first gas-liquid separator 114. The non-condensable gas is condensed by the first vent condenser 115. The condensed liquid portion is returned to the first gas-liquid separator 114, and the gaseous portion (wt%: DMC 43.5%, AIR 24.7%, MPC 23.5%, PHF 8.3%) is drawn in by the vacuum device 2. The material in the first gas-liquid separator 114 is partially refluxed (wt%: MPC 88.9%, PHF 10.4%, others 0.7%) to the first refining packed tower 111, and partially continuously collected and sent to the diphenyl carbonate preparation unit 3. The bottom components are continuously extracted at a flow rate of 19.0 tons / hr.

[0076] The material drawn from the bottom of the first refining packed column 111 directly enters the second refining packed column 121. During the distillation process, the bottom temperature (TC) of the second refining packed column 121 is 200℃, the top temperature (TD) is 180℃, and the top pressure (PB) is 2080PaA. Continuous distillation is carried out with a reflux ratio of 0.52, and the top extraction rate is 21.9 tons / hr. The high-purity DPC material in the top gas phase is condensed by the second vent condenser 123, and 0.16MPaG vapor is generated at the same time. The non-condensable gas is condensed by the second vent condenser 125. The liquid part after condensation is returned to the second gas-liquid separator 125, and the gas part (wt%: AIR 87.3%, DPC 12.7%) is drawn into the vacuum buffer tank by the vacuum device 2. The liquid material in the gas-liquid separator is partially returned to the second refining packed tower 121, and partially continuously extracted into the product storage tank 131 at a rate of 14.4 tons / hr. The heavy components at the bottom of the tower are continuously extracted at a rate of 0.16 tons / hr.

[0077] Implementation effect

[0078] The extracted product contains less than 0.01% total impurities (including but not limited to phenyl salicylate, phenyl methoxybenzoate, and xanthones), and the purity of diphenyl carbonate is above 99.99%. Under these conditions, the heat exchanger (E-05) generates 3.3 tons of steam at 0.16 MPaG per hr, saving 11.15 kgoe / ton (of product) in energy consumption. Under these conditions, the separation unit can operate continuously for over 8000 hours at an industrial scale of 130,000 tons / year, with virtually no change in the production volume and purity of diphenyl carbonate. Example 3

[0079] In Embodiment 3 of the present invention, the first refining packed tower 111 has an inner diameter of 3500 mm at the top and 2000 mm at the bottom, and a tower height (tangential) of 28000 mm. It contains two layers of packing with a height of 7000 mm, and the packing is corrugated plate. The second refining packed tower 121 has an inner diameter of 3400 mm at the top and 1000 mm at the bottom, and a tower height (tangential) of 23400 mm. It also contains two layers of packing with a height of 6000 mm, and the packing is corrugated plate.

[0080] A material containing DPC, MPC, and fresh phenol (wt%: DPC 68%, MPC 28%, PHF 4%) is continuously fed into the first refining packed column 111 at a rate of 20.8 tons / hr. During the distillation process, the bottom temperature (TA) of the first refining packed column 111 is 187°C, the top temperature (TB) is 94°C, and the top pressure (PA) is 1470 PaA. The distillation is carried out continuously at a reflux ratio of 3.73, and the top extraction rate is 29.2 tons / hr. The gaseous stream from the top of the column is condensed by the air condenser 113 and enters the first gas-liquid separator 114. The non-condensable gas is condensed by the first vent condenser 115. The condensed liquid portion is returned to the first gas-liquid separator 114, and the gaseous portion (wt%: DMC 44.4%, AIR 17.4%, MPC 28.0%, PHF 10.2%) is drawn in by the vacuum device 2. The material in gas-liquid separator 114 is partially refluxed (wt%: MPC 88.7%, PHF 10.4%, others 0.9%) to the first refining packed tower 111, and partially continuously collected and sent to the diphenyl carbonate preparation unit 3. The bottom components are continuously extracted at a flow rate of 14.5 tons / hr.

[0081] The material drawn from the bottom of the first refining packed column 111 directly enters the second refining packed column 121. During the distillation process, the bottom temperature (TC) of the second refining packed column 121 is 191℃, the top temperature (TD) is 160℃, and the top pressure (PB) is 892PaA. Continuous distillation is carried out with a reflux ratio of 0.6. The top extraction rate is 23 tons / hr. The high-purity DPC material in the gas phase at the top of the column is condensed by the evaporative condenser 123, and 0.15MPaG vapor is generated at the same time. The non-condensable gas is condensed by the second vent condenser 125. The liquid part after condensation is returned to the second gas-liquid separator 125, and the gas part (wt%: AIR, 82.4%, DPC 17.6%) is drawn into the vacuum buffer tank by the vacuum device 2. The liquid material in the second gas-liquid separator 124 is partially returned to the second refining packed tower 121, and partially continuously extracted into the product storage tank 131 at a rate of 14.4 tons / hr. The heavy components at the bottom of the tower are continuously extracted at a rate of 0.13 tons / hr.

[0082] Implementation effect

[0083] The extracted product contains less than 0.01% total impurities (including but not limited to phenyl salicylate, phenyl methoxybenzoate, and xanthones), and the purity of diphenyl carbonate is above 99.99%. Under these conditions, the evaporative condenser 123 generates 3.2 tons of steam per hr at a rate of 0.16 MPaG, saving 10.8 kgoe / ton (of product) in energy consumption. Under these conditions, the separation unit can operate continuously for over 8000 hours at an industrial scale of 130,000 tons / year, with virtually no change in the production volume and purity of diphenyl carbonate.

[0084] In another alternative embodiment, refer to Figure 2 As shown, the diphenyl carbonate preparation apparatus 33 may include: a methyl phenyl carbonate synthesis unit 31, a methyl phenyl carbonate purification unit 32, and a diphenyl carbonate synthesis unit 33; wherein, the methyl phenyl carbonate synthesis unit 31 includes: a first reactive distillation column 311, a first condenser 312, and a third reboiler 313; the first reactive distillation column 311 is used to synthesize methyl phenyl carbonate, the first condenser 312 is connected to the top of the first reactive distillation column 311; the third reboiler 313 is connected to the bottom of the first reactive distillation column 311; the methyl phenyl carbonate purification unit 32 includes: a methyl phenyl carbonate concentration column 321, a second condenser 322, a fourth reboiler 323, and anisole recovery column 324; the methyl phenyl carbonate concentration column 321 is connected to the first reactive distillation column 311, the second condenser 322, the third reboiler 323, and the third reboiler 324 respectively; A condenser 312 is connected to the bottom of the first reactive distillation column 311 for concentrating methylphenyl carbonate; a second condenser 322 is connected to the top of the methylphenyl carbonate concentration column 321; a fourth reboiler 323 is connected to the bottom of the methylphenyl carbonate concentration column 321; an anisole recovery column 324 is connected to the middle of the methylphenyl carbonate concentration column 321; the diphenyl carbonate synthesis unit 33 includes: a second reactive distillation column 331, a third condenser 332, and a fifth reboiler 333. The second reactive distillation column 331 is connected to the bottom of the methylphenyl carbonate concentration column 321 for synthesizing diphenyl carbonate; the third condenser 332 is connected to the top of the second reactive distillation column 331; and the fifth reboiler 333 is connected to the bottom of the second reactive distillation column 331.

[0085] In this embodiment of the invention, the first reactive distillation column 311 can be referred to as an MPC reactive distillation column, the methyl phenyl carbonate concentration column 321 can be referred to as an MPC concentration column, and the second reactive distillation column 331 can be referred to as a DPC reactive distillation column. The preparation apparatus provided in this embodiment of the invention, by adding an MPC purification unit and employing an MPC concentration process to directly recover most of the DMC, thereby reducing the energy consumption for separating the DMC / methanol azeotrope, and overall improving the dual reactive distillation esterification process, significantly enhancing the purity of the diphenyl carbonate product.

[0086] In another alternative embodiment, refer to Figure 2 As shown, the methyl phenyl carbonate purification unit 2 may further include: a sixth reboiler 325; the sixth reboiler 325 includes a sixth reboiler inlet and a sixth reboiler outlet, the sixth reboiler inlet is connected to the bottom of the anisole recovery tower 324, and the sixth reboiler outlet is connected to the middle of the anisole recovery tower 324 to form a heating circuit.

[0087] The descriptions and beneficial effects of the separation method and separation system in the embodiments of the present invention can be referred to the separation device described above, and will not be repeated here.

[0088] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. This disclosure is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this disclosure is limited only by the appended claims. Thus, if these modifications and variations of the invention fall within the scope of the claims of the invention and their equivalents, the invention is also intended to include these modifications and variations.

Claims

1. A high-purity diphenyl carbonate separation device, characterized in that, include: The unit comprises a first refining and separation unit, a second refining and separation unit, and a product storage unit. The first refining and separation unit includes: a first refining packed tower, a first reboiler, an air condenser, a first gas-liquid separator, and a first venting condenser; the first reboiler is connected to the bottom of the first refining packed tower to form a heating circuit; the top of the first refining packed tower, the air condenser, and the first gas-liquid separator are sequentially connected to form a circuit; the first venting condenser is connected to the air condenser and the first gas-liquid separator respectively, and is externally connected to a vacuum device to maintain the pressure at the top of the first refining packed tower at 1470~2000 PaA; the first gas-liquid separator is externally connected to a diphenyl carbonate preparation device; The second refining and separation unit includes: a second refining packed tower, a second reboiler, an evaporative condenser, a second gas-liquid separator, and a second venting condenser; the bottom of the first refining packed tower is connected to the second refining packed tower, and the second reboiler is connected to the bottom of the second refining packed tower to form a heating circuit; the top of the second refining packed tower, the evaporative condenser, and the second gas-liquid separator are sequentially connected to form a circuit; the second venting condenser is connected to the evaporative condenser and the second gas-liquid separator respectively, and is externally connected to a vacuum device to maintain the pressure at the top of the second refining packed tower at 892~2080 PaA; The product storage unit is connected to the second gas-liquid separator; The first refining packed tower is configured to receive a mixture containing diphenyl carbonate, methyl phenyl carbonate and phenol from a diphenyl carbonate preparation unit at a feed rate of not less than 20.8 tons / hr.

2. The apparatus according to claim 1, characterized in that, The first refined packed tower has an inner diameter of 2000~3800mm and a tower height of 28000mm. The first refined packed tower has two layers of packing with a packing height of 7000mm. The second refining packed tower has an inner diameter of 1000~3700mm and a tower height of 23400mm. The packing of the second refining packed tower consists of two layers with a packing height of 6000mm.

3. The apparatus according to claim 2, characterized in that, The first refining packed tower uses corrugated plates as its packing material, and / or the second refining packed tower uses corrugated plates as its packing material.

4. The apparatus according to claim 1, characterized in that, The first refining and separation unit further includes: a first separation pump, the inlet of which is connected to the bottom of the first refining packed tower, and the outlet of which is connected to the inlet of the first reboiler and the second refining packed tower, respectively. The second refining and separation unit further includes a second separation pump, the inlet of which is connected to the bottom of the second refining packed tower, and the outlet of which is connected to the inlet of the second reboiler.

5. The apparatus according to claim 1, characterized in that, The first refining and separation unit further includes: a third separation pump, the inlet of which is connected to the first gas-liquid separator, and the outlet of which is connected to the first refining packed tower and the external diphenyl carbonate preparation device, respectively. The second refining and separation unit further includes a fourth separation pump, the inlet of which is connected to the second gas-liquid separator, and the outlet of which is connected to the second refining packed tower and the product storage unit.

6. The apparatus according to any one of claims 1 to 5, characterized in that, The product storage unit includes: a product storage tank and a fifth centrifugal pump; The product storage tank is connected to the second gas-liquid separator; the fifth centrifugal pump is connected to the product storage tank.

7. A method for separating high-purity diphenyl carbonate, characterized in that, The high-purity diphenyl carbonate separation apparatus according to any one of claims 1 to 6 performs separation, comprising: The feed is continuously fed into the first refined packed tower in the first refined separation unit at a rate of 20.8 tons / hr or more. The temperature and pressure parameters of the first refined packed tower and the reflux ratio of the first gas-liquid separator in the first refined separation unit are controlled to continuously distill diphenyl carbonate. The top pressure of the first refined packed tower is 1470~2000 PaA, the top temperature is 94~103℃, the bottom temperature is 187~197℃, and the reflux ratio is 3.5:1~3.73:

1. The material after distillation in the first refining and separation unit is fed into the second refining and separation unit. The temperature and pressure parameters of the second refining packed column and the reflux ratio of the second gas-liquid separator in the second refining and separation unit are controlled to continuously distill diphenyl carbonate. The top pressure of the second refining packed column is 892~2080 PaA, the top temperature is 160~180℃, the bottom temperature is 191~200℃, and the reflux ratio is 0.52:1~0.6:

1. The diphenyl carbonate obtained after distillation in the second refining and separation unit is sent to the product storage unit.

8. A diphenyl carbonate preparation system, characterized in that, include: A diphenyl carbonate preparation apparatus, a vacuum apparatus, and a high-purity diphenyl carbonate separation apparatus as described in any one of claims 1 to 6; The diphenyl carbonate preparation device is connected to the inlet of the first refining packed tower and the outlet of the first gas-liquid separator, respectively. The diphenyl carbonate preparation device is used to prepare diphenyl carbonate and send the prepared diphenyl carbonate into the first refining packed tower for separation and purification by the high-purity diphenyl carbonate separation device. The vacuum device is connected to the vent port of the first vent condenser and the vent port of the second vent condenser, respectively, and is used to extract the gas from the first vent condenser and the second vent condenser.

9. The system according to claim 8, characterized in that, The diphenyl carbonate preparation apparatus includes: a methyl phenyl carbonate synthesis unit, a methyl phenyl carbonate purification unit, and a diphenyl carbonate synthesis unit; The methyl phenyl carbonate synthesis unit includes: a first reactive distillation column, a first condenser, and a third reboiler; the first reactive distillation column is used to synthesize methyl phenyl carbonate, the first condenser is connected to the top of the first reactive distillation column, and the third reboiler is connected to the bottom of the first reactive distillation column; The methyl phenyl carbonate purification unit includes: a methyl phenyl carbonate concentration tower, a second condenser, a fourth reboiler, and an anisole recovery tower; the methyl phenyl carbonate concentration tower is connected to the bottom of the first condenser and the first reactive distillation tower, respectively, for concentrating methyl phenyl carbonate; the second condenser is connected to the top of the methyl phenyl carbonate concentration tower; the fourth reboiler is connected to the bottom of the methyl phenyl carbonate concentration tower; and the anisole recovery tower is connected to the middle of the methyl phenyl carbonate concentration tower. The diphenyl carbonate synthesis unit includes a second reactive distillation column, a third condenser, and a fifth reboiler. The second reactive distillation column is connected to the bottom of the methyl phenyl carbonate concentration column and is used to synthesize diphenyl carbonate. The third condenser is connected to the top of the second reactive distillation column. The fifth reboiler is connected to the bottom of the second reactive distillation column.

10. The system according to claim 9, characterized in that, The feed rate of the first refining packed tower is not less than 20.8 tons / hr; the top pressure of the first refining packed tower is 1470~2000 PaA, the top temperature is 94~103℃, the bottom temperature is 187~197℃; and the reflux ratio is 3.5:1~3.73:

1. The second refining packed tower has a top pressure of 892~2080 PaA, a top temperature of 160~180℃, a bottom temperature of 191~200℃, and a reflux ratio of 0.52:1~0.6:1.

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