A system and method for improving the purity of bisphenol a

Abstract

The present application relates to the technical field of bisphenol A production, and particularly relates to a system and method for improving the purity of bisphenol A, which realizes the purification of bisphenol A and the recovery of phenol, improves the purity of bisphenol A to above 99.95%, and reduces the production cost. The system comprises a heater and a flash tank. The gas phase at the top of the flash tank is connected in series with a first condenser and a vent tank. The gas phase of the vent tank is connected with a vacuum system, and the liquid phase is recovered to the system by a first conveying pump. The liquid phase at the bottom of the flash tank is sent to a stripping tower by a second conveying pump. The gas phase at the top of the stripping tower is connected in series with a second condenser and a collection tank. The gas phase of the collection tank is connected with a vacuum system, and the liquid phase is recovered to the system by a fourth conveying pump. The liquid phase at the bottom of the stripping tower is sent to output bisphenol A by a third conveying pump.

Description

Technical Field

[0001] This invention relates to the field of bisphenol A production technology, specifically a system and method for improving the purity of bisphenol A. Background Technology

[0002] In the bisphenol A (BPA) production process, the molten BPA product from centrifuges or vacuum filters often contains phenol and moisture, resulting in a BPA purity that cannot reach 99.90% or higher. This affects the purity of the BPA, increasing operating costs and hindering business development. Therefore, there is an urgent need to develop new equipment to solve the problem of low BPA purity. Summary of the Invention

[0003] To address the aforementioned problems, this invention provides a system and method for improving the purity of bisphenol A, achieving bisphenol A purification and phenol recovery, increasing the purity of bisphenol A to over 99.95%, and reducing production costs. The technical solution adopted by this invention is as follows: A system for improving the purity of bisphenol A includes a heater and a flash tank. The top gas phase of the flash tank is connected in series with a first condenser and a vent tank. The gas phase of the vent tank is connected to a vacuum system, and the liquid phase is recovered to the system via a first transfer pump. The bottom liquid phase of the flash tank is sent to a stripping tower via a second transfer pump. The top gas phase of the stripping tower is connected in series with a second condenser and a collection tank. The gas phase of the collection tank is connected to a vacuum system, and the liquid phase is recovered to the system via a fourth transfer pump. The bottom liquid phase of the stripping tower is transported by a third transfer pump to produce bisphenol A.

[0004] The stripping tower of the above-mentioned system for improving the purity of bisphenol A has a specification of DN1000 / 1800×20693 and is divided into three layers. Two layers of BX500 structured packing are installed inside the tower. Each packing layer is 3200mm high. A thermocouple and an automatic temperature control system are designed in the middle of the packing.

[0005] The present invention also provides a method for improving the purity of bisphenol A, using the above-described system, comprising the following steps: Materials containing phenol and moisture enter a melting heater, where the temperature is raised to 167-173℃, and then enter a bisphenol A stripping flash tank. The pressure inside the flash tank is around -95 kPa, where phenol and moisture are flashed out of the material. The vapor phase passes through a first condenser and enters a vent tank to recover any entrained phenol and moisture in the material. The liquid material in the flash tank is then transported by a second transfer pump to a stripping tower to further remove phenol and moisture, increasing the purity of bisphenol A to over 99.95%.

[0006] The above-mentioned method for improving the purity of bisphenol A includes a stripping tower with a top temperature of 167℃, a bottom temperature of 168-173℃, and a bottom pressure of -85 to -90 kPa. A trough-type distributor is designed to ensure uniform distribution of the material entering the storage tank. The horizontal deviation of the distributor installation is ≤3mm. The first packing disc is at a 45° angle to the packing support bars, and subsequent packing discs are at 90° to each other. 0.5 MPa steam is heated to 215℃ and enters the stripping tower from the middle to remove phenol from the material. 0.5 MPa nitrogen is heated to 190℃ and enters the stripping tower from the middle to remove moisture from the material. Steam tracing is installed on the tower wall, and precision filters are installed on both the steam and nitrogen pipelines.

[0007] The beneficial effects of this invention are: through this system, phenol and moisture in materials can be removed, the purity of bisphenol A can be improved, the system cost can be reduced, and the economic benefits can be improved. Attached Figure Description

[0008] Figure 1 This is a schematic diagram of the system structure according to an embodiment of the present invention; Figure 2 This is a schematic diagram of a stripping tower according to an embodiment of the present invention.

[0009] Figure label: 1-Heater; 2-Flash tank; 3-First condenser; 4-Vent tank; 5-First transfer pump; 6-Second transfer pump; 7-Stripping tower; 8-Second condenser; 9-Collection tank; 10-Third transfer pump; 11-Fourth transfer pump; 71-Top outlet of the tower; 72-Bottom outlet of the tower; 73-Packing; 74-Steam inlet; 75-Nitrogen inlet; 76-Material inlet; 77-Distributor. Detailed Implementation

[0010] The technical solutions of this application will be described in detail below with reference to the accompanying drawings. The following embodiments are illustrative; unless otherwise specifically stated, the relative arrangement and numerical expressions of components and steps described in these embodiments should not be construed as limiting the scope of this application. The following description of exemplary embodiments is merely illustrative and is not intended to limit this application or its application or use in any way. Techniques, methods, and apparatus known to those skilled in the art may not be discussed in detail here, but where applicable, these techniques, methods, and apparatuses should be considered part of this specification.

[0011] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. Unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. When the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof. Unless otherwise stated, the terms "installed," "connected," "linked," etc., in this application should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; 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; they can refer to an internal connection between two elements or an interaction between two elements. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0012] For ease of description, the use of terms such as "upper," "lower," "left," "right," "bottom," and "top" in this application does not limit the structure. It is merely for the purpose of understanding the structural principles of this application in conjunction with the accompanying drawings, and does not indicate or imply that the equipment or components referred to must have a specific orientation, or be constructed and operated in a specific orientation. It should not be construed as a limitation of this application.

[0013] A system for improving the purity of bisphenol A includes a heater 1 and a flash tank 2. The top gas phase of the flash tank 2 is connected in series with a first condenser 3 and a vent tank 4. The gas phase of the vent tank 4 is connected to a vacuum system, and the liquid phase is recovered to the system via a first transfer pump 5. The bottom liquid phase of the flash tank 2 is sent to a stripping tower 7 via a second transfer pump 6. The top gas phase of the stripping tower 7 is connected in series with a second condenser 8 and a collection tank 9. The gas phase of the collection tank 9 is connected to a vacuum system, and the liquid phase is recovered to the system via a fourth transfer pump. The liquid phase at the bottom outlet 72 of the stripping tower 7 is transported by a third transfer pump 10 to produce bisphenol A.

[0014] The working method of the above system includes the following steps: Materials containing phenol and moisture enter the melting heater 1, where the temperature is raised to 167-173℃, and then enter the bisphenol A stripping flash tank 2. The pressure inside the flash tank 2 is around -95 kPa, where phenol and moisture are flashed out of the material. The vapor phase passes through the first condenser 3 and enters the vent tank 4 to recover the phenol and moisture entrained in the material, reducing production costs. The liquid material in the flash tank 2 is transported to the stripping tower 7 by the second transfer pump 6 to further remove phenol and moisture from the material, increasing the purity of bisphenol A to over 99.95%.

[0015] The stripping tower 7 has specifications of DN1000 / 1800×20693mm. The equipment is divided into three layers, which are thinner in the middle and thicker at both ends, similar to a dumbbell. The equipment is equipped with two layers of BX500 regular packing material, with a packing height of 3200mm for each layer. A thermocouple and an automatic temperature control system are designed in the middle of the packing. After each support is welded to the tower wall, its surface should be on the same horizontal plane, with a horizontality deviation of ≤3mm.

[0016] The material in the stripping tower 7 enters through the material inlet 76 at the top of the tower. The top temperature is controlled at 167℃, the bottom temperature at 168-173℃, and the bottom pressure at -85~-90Kpa. A trough-type distributor 77 is designed to ensure uniform distribution of the material entering the tower. The horizontal deviation of the distributor 77 is ≤3mm. The structured packing is installed horizontally. The first packing disc is at a 45° angle to the packing support grid, and subsequent packing discs are at 90° to each other. 0.5Mpa steam is heated to 215℃ and enters the stripping tower 7 through the central steam inlet 74 to remove phenol from the material. 0.5Mpa nitrogen is heated to 190℃ and enters the stripping tower 7 through the central nitrogen inlet 75 to remove moisture from the material. The tower wall is equipped with steam tracing. Precision filters are installed on both the steam and nitrogen pipelines to remove impurities entrained in the nitrogen and steam.

[0017] Furthermore, the top outlet 71 of the stripping tower 7 is connected in series with a second condenser 8 and a liquid collection tank 9 to prevent liquid from being carried into the subsequent system by the gas phase pipeline. The distribution holes are perforated. The hole diameter error is less than ±0.05mm; the perforation direction is the liquid flow direction, and the horizontal deviation is less than ±0.05mm.

[0018] Furthermore, the weld leg height of all interlocking welds and fillet welds is equal to the thickness of the thinner component, and they are continuous welds.

[0019] The above are merely preferred embodiments of this application. It should be noted that, for those skilled in the art, several structural changes or improvements can be made without departing from the principles of this application, and these changes or improvements should also be considered within the scope of protection of this application.

Claims

1. A system for improving the purity of bisphenol A, characterized in that: The system includes a heater (1) and a flash tank (2). The top gas phase of the flash tank (2) is connected in series with a first condenser (3) and a vent tank (4). The gas phase of the vent tank (4) is connected to a vacuum system, and the liquid phase is recovered to the system via a first transfer pump (5). The bottom liquid phase of the flash tank (2) is sent to a stripping tower (7) via a second transfer pump (6). The top gas phase of the stripping tower (7) is connected in series with a second condenser (8) and a collection tank (9). The gas phase of the collection tank (9) is connected to a vacuum system, and the liquid phase is recovered to the system via a fourth transfer pump. The bottom liquid phase of the stripping tower (7) is transported by a third transfer pump (10) to produce bisphenol A.

2. The system for improving the purity of bisphenol A according to claim 1, characterized in that: The stripping tower (7) has a specification of DN1000 / 1800×20693 and is divided into three layers. It contains two layers of BX500 structured packing, each layer of packing is 3200mm high, and thermocouples and automatic temperature control systems are designed in the middle of the packing.

3. A method for improving the purity of bisphenol A, characterized in that, Using the system of claim 1 or 2 includes the following steps: Materials containing phenol and moisture enter the melting heater (1), and after heating, the temperature is raised to 167-173℃, and then enters the bisphenol A stripping flash tank (2). The pressure inside the flash tank (2) is about -95Kpa, and the phenol and moisture in the material are flashed out. The gas phase enters the vent tank (4) through the first condenser (3) to recover the phenol and moisture entrained in the material. The liquid material in the flash tank (2) is transported to the stripping tower (7) by the second transfer pump (6) to further remove the phenol and moisture in the material and increase the purity of bisphenol A to more than 99.95%.

4. The method for improving the purity of bisphenol A according to claim 3, characterized in that, The stripping tower (7) has a top temperature of 167℃, a bottom temperature of 168-173℃, and a bottom pressure of -85~-90Kpa. A trough-type distributor is designed to ensure that the material entering the storage tank is evenly distributed. The horizontal deviation of the distributor installation is ≤3mm. The first packing disc is at 45° to the packing support grid, and the subsequent packing discs are at 90° to each other. 0.5Mpa steam is heated to 215℃ and enters the stripping tower (7) from the middle to remove phenol from the material. 0.5Mpa nitrogen is heated to 190℃ and enters the stripping tower (7) from the middle to remove moisture from the material. Steam tracing is installed on the tower wall, and precision filters are installed on both the steam and nitrogen pipelines.

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