A phthalic anhydride preparation device with a heating and heat-insulating naphthalene storage tank

Abstract

The utility model relates to a chemical equipment field, concretely relates to a phthalic anhydride preparation device with heating and heat preservation naphthalene storage tank, including air compressor, o-xylene storage tank, naphthalene storage tank, oxidation reactor and crude product storage tank, air compressor, o-xylene storage tank, naphthalene storage tank are connected with oxidation reactor through the pipeline, the oxidation reactor is connected with crude product storage tank through the pipeline, the naphthalene storage tank is equipped with heating row pipe and heating coil pipe, the heating coil pipe is from the bottom of naphthalene storage tank and is distributed on the lateral wall of naphthalene storage tank in spiral shape, the pitch between heating coil pipe is variable pitch, from the bottom of naphthalene storage tank upwards, the pitch gradually becomes big. The naphthalene storage tank can melt solid naphthalene quickly when heating and melting naphthalene, can be segmented heating when heat preservation, prevents naphthalene liquid surface temperature from being too high, reduces naphthalene liquid surface evaporation speed.

Description

Technical Field

[0001] This utility model relates to the field of chemical equipment, specifically to a phthalic anhydride preparation device with a heated and insulated naphthalene storage tank. Background Technology

[0002] Phthalic anhydride, or phthalic anhydride for short, is an important chemical raw material. In modern industrial production, phthalic anhydride is mainly prepared by the catalytic oxidation of o-xylene. This method accounts for the vast majority of global production capacity because the phthalic anhydride prepared by the catalytic oxidation of o-xylene has a high conversion rate, higher product purity, and lighter color, meeting the requirements of high-end plasticizers and resins. However, with the rising price of raw material o-xylene (7000-8000 RMB / ton), the profit margin of phthalic anhydride prepared by the catalytic oxidation of o-xylene has been compressed. Therefore, seeking a low-cost raw material to replace o-xylene has become a research direction for various manufacturers. The air oxidation of naphthalene to prepare phthalic anhydride is a traditional process. Currently, the price of naphthalene (5000-6000 RMB) is much lower than that of o-xylene. However, the phthalic anhydride prepared by air oxidation of naphthalene alone has slightly more impurities (such as naphthoquinone, phthalic acid, etc.) and a darker color, making it unsuitable for use in high-end plasticizers and resins. Therefore, research has begun on the co-feeding of naphthalene and o-xylene. However, naphthalene has a melting point of 78-80 degrees Celsius, and solid naphthalene cannot be pumped. The problem of feeding solid naphthalene needs to be solved. Summary of the Invention

[0003] To overcome the problem that naphthalene is solid at room temperature and inconvenient to feed, a phthalic anhydride preparation device with a heated and insulated naphthalene storage tank is needed. In addition, since naphthalene is easy to evaporate, to prevent the evaporating naphthalene from clogging the solid naphthalene feed port due to excessively high temperature during insulation, additional insulation components are required.

[0004] In view of this, the present invention provides a phthalic anhydride preparation apparatus with a heated and insulated naphthalene storage tank, comprising an air compressor, an o-xylene storage tank, a naphthalene storage tank, an oxidation reactor, and a crude product storage tank. The air compressor, the o-xylene storage tank, and the naphthalene storage tank are connected to the oxidation reactor via pipelines. The oxidation reactor is connected to the crude product storage tank via pipelines. The naphthalene storage tank is provided with heating tubes and heating coils. The heating coils are spirally distributed on the side wall of the naphthalene storage tank from the bottom. The pitch between the heating coils is variable, gradually increasing from the bottom of the naphthalene storage tank upwards.

[0005] Preferably, the side wall of the naphthalene storage tank is provided with a second steam inlet and a second steam outlet, which are respectively connected to the two ends of the heating tube.

[0006] Preferably, the side wall of the naphthalene storage tank is provided with a first steam inlet and a first steam outlet, and the first steam inlet and the first steam outlet are respectively connected to the two ends of the heating coil.

[0007] Preferably, the heating tubes are laid in parallel at the bottom of the naphthalene storage tank, the distance between two adjacent tubes is 10~30cm, and the diameter of the heating tubes is 3~6cm.

[0008] Preferably, a temperature sensor is provided on the side wall of the naphthalene storage tank.

[0009] Preferably, the temperature sensor is provided in multiple locations, and the multiple temperature sensors are distributed at different heights.

[0010] Preferably, the heating tubes and heating coils are equipped with solenoid valves.

[0011] Preferably, the solenoid valve is electrically connected to the temperature sensor, and the opening and closing amplitude of the solenoid valve can be automatically controlled according to the temperature displayed by the temperature sensor.

[0012] Preferably, the top of the naphthalene storage tank is provided with a feeding port, and the feeding port is covered with a cover plate.

[0013] Preferably: the outlet of the air compressor is connected to an air heater via a pipeline; the outlet of the o-xylene storage tank is connected to a first preheater via a pipeline; the other end of the first preheater is connected to a first mixer via a pipeline; the other end of the first mixer is connected to the top of the oxidation reactor via a pipeline; the outlet of the naphthalene storage unit is connected to a second preheater via a pipeline; the other end of the second preheater is connected to a second mixer via a pipeline; the other end of the second mixer is connected to the top of the oxidation reactor via a pipeline; the outlet of the air heater is connected to both the first and second mixers via pipelines; the bottom of the oxidation reactor is connected to a first condenser and a second condenser via pipelines; and the outlet of the second condenser is connected to a crude product storage tank.

[0014] The beneficial effects of this invention are as follows: This invention provides a phthalic anhydride preparation apparatus with a heated and insulated naphthalene storage tank, comprising an air compressor, an o-xylene storage tank, a naphthalene storage tank, an oxidation reactor, and a crude product storage tank. The air compressor, o-xylene storage tank, and naphthalene storage tank are connected to the oxidation reactor via pipelines. The oxidation reactor is connected to the crude product storage tank via pipelines. The naphthalene storage tank is equipped with heating tubes and heating coils. The heating coils are spirally distributed on the side wall of the naphthalene storage tank from the bottom. The pitch between the heating coils is variable, gradually increasing from the bottom of the naphthalene storage tank upwards. When the naphthalene storage tank provided by this invention is heated and melted, it can quickly melt solid naphthalene. When insulated, the heating amount can be controlled in stages to prevent the naphthalene liquid surface temperature from becoming too high and reduce the evaporation rate of the naphthalene liquid surface. Attached Figure Description

[0015] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0016] Figure 1 This is a schematic diagram of a phthalic anhydride preparation apparatus with a heated and insulated naphthalene storage tank in an embodiment of this utility model; Figure 2 yes Figure 1 Schematic diagram of the naphthalene storage tank; Figure 3 yes Figure 2 Schematic diagram of the interior of the naphthalene storage tank; Figure 4 yes Figure 2 Top view of the interior of the naphthalene storage tank; Figure 5 yes Figure 4 Sectional view along plane A-A.

[0017] The component names and their numbers in the diagram are as follows: 100. A phthalic anhydride preparation apparatus with a heated and insulated naphthalene storage tank; 1. Air compressor; 11. Air heater; 2. o-xylene storage tank; 21. First preheater; 211. First feed pump; 22. First mixer; 24. First feed pump; 3. Naphthalene storage tank; 31. First steam inlet; 32. First steam outlet; 33. Second steam inlet; 34. Second steam outlet; 35. Heating tubes; 36. Heating coil; 37. Feed port; 38. Second preheater; 381. Second feed pump; 39. Second mixer; 4. Oxidation reactor; 41. First condenser; 42. Second condenser; 5. Crude product storage tank. Detailed Implementation

[0018] To make the technical problems, technical solutions, and beneficial effects of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.

[0019] It should be noted that when a component is referred to as "connected to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0020] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" 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; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0021] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model 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. Therefore, they should not be construed as limitations on this utility model.

[0022] Throughout this specification, reference to "an embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of this application. Therefore, the phrases "in one embodiment," "in some embodiments," or "in some of these embodiments" appear in various places throughout the specification, and not all refer to the same embodiment. Furthermore, in one or more embodiments, a particular feature, structure, or characteristic may be combined in any suitable manner.

[0023] Referring to the air compressor 1 in Figure 1, this utility model provides a phthalic anhydride preparation apparatus 100 with a heated and insulated naphthalene storage tank, including an air compressor 1, an o-xylene storage tank 2, a naphthalene storage tank 3, an oxidation reactor 4, and a crude product storage tank 5. The outlet of the air compressor 1 is connected to an air heater 11 via a pipeline. The outlet of the o-xylene storage tank 2 is connected to a first preheater 21 via a pipeline. The other end of the first preheater 21 is connected to a first mixer 22 via a pipeline. The other end of the first mixer 22 is connected to the top of the oxidation reactor 4 via a pipeline. The outlet of the naphthalene storage tank 3 is connected to a second preheater 38 via a pipeline. The other end of the second preheater 38 is connected to a second mixer 39 via a pipeline. The other end of the second mixer 39 is connected to the top of the oxidation reactor 4 via a pipeline. The outlet of the air heater 11 is connected to both the first mixer 22 and the second mixer 39 via pipelines. The bottom of the oxidation reactor 4 is sequentially connected to a first condenser 41 and a second condenser 42 via pipelines. The outlet of the second condenser 42 is connected to the crude product storage tank 5.

[0024] The phthalic anhydride preparation apparatus 100 with a heated and insulated naphthalene storage tank provided by this utility model operates as follows: Air compressed by the air compressor 1 enters the air heater 11 for preheating. The preheated air is then divided into two streams, entering the first mixer 22 and the second mixer 39 respectively. o-xylene stored in the o-xylene storage tank 2 enters the first preheater 21 via a pipeline for preheating. The preheated o-xylene then enters the first mixer 22 and mixes with the incoming air, vaporizing and being fed into the top of the oxidation reactor 4. Naphthalene stored in the naphthalene storage tank 3 enters the second preheater 38 via a pipeline for preheating. The preheated naphthalene then enters the second mixer 39 and mixes with the incoming air, vaporizing and being fed into the top of the oxidation reactor 4. Oxidation reactor 4 contains an oxidation catalyst. The o-xylene and naphthalene entering the oxidation reactor 4 are oxidized by air to phthalic anhydride. The reaction temperature in oxidation reactor 4 is 360~380 degrees Celsius. At this time, the phthalic anhydride is in a gaseous state and enters the first condenser 41 from the bottom of oxidation reactor 4 for pre-cooling. Then it enters the second condenser 42 for further cooling to below the boiling point, becoming liquid phthalic anhydride. It is then stored in crude product storage tank 5 for subsequent distillation and purification.

[0025] Naphthalene has a melting point of 78-80 degrees Celsius. To facilitate transportation and unloading, the naphthalene purchased by our company is packaged in naphthalene chip ton bags. In order to facilitate the subsequent feeding of solid naphthalene into the naphthalene storage tank 3, this utility model provides a naphthalene storage tank 3, which facilitates heating and melting of solid naphthalene and keeping it warm.

[0026] In some embodiments, a first feed pump 211 is provided between the first preheater 21 and the o-xylene storage tank 2, and a first feed pump 211 is provided between the second preheater 38 and the naphthalene storage tank 3.

[0027] refer to Figures 2-5 As shown, the bottom of the naphthalene storage tank 3 is provided with a heating tube 35, and the side wall is provided with a heating coil 36.

[0028] Specifically, the naphthalene storage tank 3 is cylindrical in shape with a cover plate on top. The top of the naphthalene storage tank 3 has a feed port 37, the bottom has heating tubes 35, and the side walls have heating coils 36. The feed port 37 is covered with a cover plate. High-temperature steam can be introduced into the heating tubes 35, and high-temperature steam or hot water at 85-95 degrees Celsius can be introduced into the heating coils 36. Naphthalene has a melting point of 78-80 degrees Celsius. To melt naphthalene into a liquid, the temperature inside the naphthalene storage tank 3 needs to be raised to above 80 degrees Celsius. However, because naphthalene evaporates easily, the evaporated naphthalene condenses at the lower temperature at the top, especially at the openable feed port, causing the cover plate on the feed port to stick and become difficult to open. Therefore, the temperature inside the first steam inlet 31 cannot be too high. Once the naphthalene storage tank 3 is full of solid naphthalene, high-temperature steam is introduced into the heating tube 35 to melt the solid naphthalene into a liquid. After all the solid naphthalene in the storage tank 3 has turned into a liquid, the introduction of high-temperature steam into the heating tube 35 is stopped, and hot water at 85-95 degrees Celsius is introduced into the heating coil 36 to maintain the temperature and prevent the liquid naphthalene from re-solidifying due to a drop in temperature. In special circumstances where it is necessary to quickly melt the solid naphthalene in the storage tank 3, high-temperature steam can be introduced into the heating coil 36 to work in conjunction with the heating tube 35, accelerating the heating process.

[0029] Specifically, the heating tubes 35 are laid parallel to each other at the bottom of the naphthalene storage tank 3, with a distance of 10-30 cm between adjacent tubes, and a diameter of 3-6 cm for each tube. Heating coils 36 are spirally distributed along the side wall of the naphthalene storage tank 3 from the bottom, with a variable pitch that gradually increases from the bottom upwards. This arrangement ensures that when hot water is introduced into the heating coils 36, the lower layer absorbs more heat and the upper layer absorbs less heat when heating the naphthalene in the tank 3, preventing the upper layer from becoming too hot and reducing the evaporation rate of naphthalene at the liquid surface.

[0030] In some embodiments, the outlet of the high-pressure steam in the first preheater 21 and / or the second preheater 38 is connected to the inlet of the heating tube 35, so that the steam after heat exchange in the first preheater 21 and / or the second preheater 38 can be used to heat the solid naphthalene in the naphthalene storage tank 3, making full use of the heat source.

[0031] In some embodiments, the side wall of the naphthalene storage tank 3 is provided with a first steam inlet 31 and a first steam outlet 32, a second steam inlet 33 and a second steam outlet 34, which are respectively connected to both ends of the heating tube 35, one as a steam inlet and the other as a steam outlet. The first steam inlet 31 and the first steam outlet 32 ​​are respectively connected to both ends of the heating coil 36. When hot water is introduced into the heating coil 36, the first steam inlet 31 is the hot water inlet and the first steam outlet 32 ​​is the hot water outlet. When high-temperature steam is introduced into the heating coil 36, the first steam outlet 32 ​​is the steam inlet and the first steam inlet 31 is the steam outlet.

[0032] In some embodiments, temperature sensors are provided on the side wall of the naphthalene storage tank 3. Typically, the volume of the naphthalene storage tank 3 is several hundred cubic meters, and its height reaches tens of meters, thus requiring multiple temperature sensors. Specifically, multiple temperature sensors are installed at different heights on the side wall of the naphthalene storage tank 3 to measure the temperature of naphthalene at different liquid levels.

[0033] In some embodiments, solenoid valves are provided at the inlets of the heating tube 35 and the heating coil 36. The solenoid valves are electrically connected to the temperature sensor and can automatically control the opening and closing amplitude of the solenoid valves according to the temperature.

[0034] The naphthalene storage tank 3 provided by this utility model can quickly melt solid naphthalene by introducing high-pressure steam into the heating tube 35 when heating and melting naphthalene. When keeping it warm, the liquid naphthalene can be heated in segments and with different heating amounts along the vertical height through the heating coils 36 with different pitches, so as to prevent the naphthalene liquid surface temperature from being too high and reduce the evaporation rate of the naphthalene liquid surface.

[0035] Based on the above-described preferred embodiments of this utility model, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the scope of this utility model. The technical scope of this utility model is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A phthalic anhydride preparation apparatus with a heated and insulated naphthalene storage tank, characterized in that: The system includes an air compressor (1), an o-xylene storage tank (2), a naphthalene storage tank (3), an oxidation reactor (4), and a crude product storage tank (5). The air compressor (1), the o-xylene storage tank (2), and the naphthalene storage tank (3) are connected to the oxidation reactor (4) via pipelines. The oxidation reactor (4) is connected to the crude product storage tank (5) via pipelines. The naphthalene storage tank (3) is equipped with heating tubes (35) and heating coils (36). The heating coils (36) are spirally distributed on the side wall of the naphthalene storage tank (3) from the bottom of the naphthalene storage tank (3). The pitch between the heating coils (36) is variable, and the pitch gradually increases from the bottom of the naphthalene storage tank (3) upwards.

2. The phthalic anhydride preparation apparatus with a heated and insulated naphthalene storage tank according to claim 1, characterized in that: The side wall of the naphthalene storage tank (3) is provided with a second steam inlet (33) and a second steam outlet (34), which are respectively connected to the two ends of the heating tube (35).

3. The phthalic anhydride preparation apparatus with a heated and insulated naphthalene storage tank according to claim 1, characterized in that: The side wall of the naphthalene storage tank (3) is provided with a first steam inlet (31) and a first steam outlet (32), and the first steam inlet (31) and the first steam outlet (32) are respectively connected to the two ends of the heating coil (36).

4. The phthalic anhydride preparation apparatus with a heated and insulated naphthalene storage tank according to claim 1, characterized in that: The heating tubes (35) are laid in parallel at the bottom of the naphthalene storage tank (3), with a distance of 10~30cm between two adjacent tubes and a diameter of 3~6cm for the heating tubes (35).

5. The phthalic anhydride preparation apparatus with a heated and insulated naphthalene storage tank according to claim 1, characterized in that: A temperature sensor is provided on the side wall of the naphthalene storage tank (3).

6. The phthalic anhydride preparation apparatus with a heated and insulated naphthalene storage tank according to claim 5, characterized in that: The temperature sensor is provided in multiple locations, and the multiple temperature sensors are distributed at different heights.

7. The phthalic anhydride preparation apparatus with a heated and insulated naphthalene storage tank according to claim 6, characterized in that: Solenoid valves are provided on the heating tubes (35) and heating coils (36).

8. The phthalic anhydride preparation apparatus with a heated and insulated naphthalene storage tank according to claim 7, characterized in that: The solenoid valve is electrically connected to the temperature sensor, and the opening and closing amplitude of the solenoid valve can be automatically controlled according to the temperature displayed by the temperature sensor.

9. The phthalic anhydride preparation apparatus with a heated and insulated naphthalene storage tank according to claim 8, characterized in that: The top of the naphthalene storage tank (3) is provided with a feeding port (37), and the feeding port (37) is covered with a cover plate.

10. The phthalic anhydride preparation apparatus with a heated and insulated naphthalene storage tank according to any one of claims 1 to 9, characterized in that: The outlet of the air compressor (1) is connected to an air heater (11) via a pipeline. The outlet of the o-xylene storage tank (2) is connected to a first preheater (21) via a pipeline. The other end of the first preheater (21) is connected to a first mixer (22) via a pipeline. The other end of the first mixer (22) is connected to the top of the oxidation reactor (4) via a pipeline. The outlet of the naphthalene storage tank (3) is connected to a second preheater (38) via a pipeline. The other end of the second preheater (38) is connected to a second mixer (39) via a pipeline. The other end of the second mixer (39) is connected to the top of the oxidation reactor (4) via a pipeline. The outlet of the air heater (11) is connected to the first mixer (22) and the second mixer (39) via pipelines respectively. The bottom of the oxidation reactor (4) is connected to a first condenser (41) and a second condenser (42) in sequence via pipelines. The outlet of the second condenser (42) is connected to a crude product storage tank (5).

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