Phthalic anhydride raw material industrial naphthalene purification feeding device and phthalic anhydride production device

Abstract

The utility model provides a phthalic anhydride raw material industrial naphthalene purification feeding device and a phthalic anhydride production device.The phthalic anhydride raw material industrial naphthalene purification feeding device comprises a naphthalene heater, a naphthalene inlet of the naphthalene heater is connected with a feeding pipe, and the naphthalene heater is used for heating raw material naphthalene; a buffer area, a filler layer, a rectifying layer and a heating area are sequentially arranged in the naphthalene purification rectifying tower from top to bottom, a gas phase outlet is formed in the top of the naphthalene purification rectifying tower, and a non-volatile matter outlet is formed in the bottom of the naphthalene purification rectifying tower; the side part of the naphthalene purification rectifying tower is provided with a feeding hole, the feeding hole is connected with a naphthalene outlet of the naphthalene heater, the rectifying layer is used for purifying and separating raw material naphthalene, the heating area is used for heating and evaporating a liquid phase, the filler layer is used for removing the liquid phase entrained in a gas phase, and the buffer area is used for reducing the linear velocity of the rising gas phase and further removing liquid drops entrained in the gas phase. The device is reasonable in design, simple in structure, convenient to install and capable of effectively separating and removing liquid and entrained heavy components in a gas phase.

Description

Technical Field

[0001] The utility model belongs to the technical field of phthalic anhydride production process, and particularly relates to a phthalic anhydride raw material industrial naphthalene purification feeding device and a phthalic anhydride production device. Background Art

[0002] The naphthalene evaporation feeding system is an important key process in the phthalic anhydride production unit. In the actual production process, because industrial naphthalene contains more impurities, lower purity, and a large number of non-volatile components, the recombinant and non-volatile components of industrial naphthalene enter the reactor and react with the catalyst to generate phthalic anhydride. There are many impurities in the reaction gas, which enter the subsequent products and have a greater impact on product quality.

[0003] Therefore, in the catalytic oxidation reaction of phthalic anhydride produced in the reactor using industrial naphthalene as raw material, the naphthalene must be heated and evaporated by a naphthalene evaporator before mixing with air to ensure that pure naphthalene gas with high purity is used. The naphthalene evaporator has two functions:

[0004] 1. Ensure the vaporization effect of industrial naphthalene, realize the complete vaporization of high-temperature liquid naphthalene into gaseous naphthalene, and remove the droplets in the steam;

[0005] 2. Industrial naphthalene contains many impurities. Medium-pressure steam is used to heat the liquid naphthalene so that its heavy components do not enter the reactor, thus avoiding excessive temperature and catalyst deactivation affecting product quality.

[0006] The existing commonly used naphthalene evaporation device is generally a horizontal evaporator, with a built-in U-tube heat exchanger, which simply vaporizes liquid naphthalene into steam without the effect of purification and rectification. After long-term operation, the heavy components and non-volatile components in industrial naphthalene enter the gas phase pipeline and vaporizer with naphthalene steam, causing the gas phase resistance to increase, and the aggregates are too much, blocking the gas phase pipeline and attaching to the catalyst surface to affect the catalytic performance of the active components of the catalyst. At the same time, if the naphthalene evaporator outlet carries liquid, due to the small volume and fast flow rate of the naphthalene evaporator, part of the industrial naphthalene cannot be fully vaporized and enters the reactor, which will cause the catalyst in the reactor to run hot, and in severe cases, the explosion-proof membrane of the reactor will be exploded, affecting the safe operation of the phthalic anhydride production device. Moreover, the horizontal naphthalene evaporator has the disadvantages of small volume, high energy consumption, difficult cleaning, easy blocking, etc. Moreover, the horizontal naphthalene evaporator is to increase the defoamer in the outlet pipeline of the evaporator, which may cause the safety production hidden danger caused by the poor vaporization of raw materials.

[0007] Alternatively, in order to obtain pure naphthalene vapor, naphthalene is evaporated in the form of a naphthalene evaporation device using a combination of multiple devices. Using a combination of multiple devices means that naphthalene is processed multiple times, resulting in a complex process, high energy consumption, and difficulty in control. Utility Model Content

[0008] In view of the above-mentioned technical problems existing in the prior art, an embodiment of the utility model provides a feeding device for purifying industrial naphthalene, a raw material of phthalic anhydride.

[0009] The technical solution adopted in the embodiment of the utility model is: a phthalic anhydride raw material industrial naphthalene purification feeding device, comprising:

[0010] A naphthalene heater, wherein a naphthalene inlet of the naphthalene heater is connected to a feed pipe, and the naphthalene heater is used to heat the raw material naphthalene;

[0011] A naphthalene purification distillation tower is provided with a buffer zone, a packing layer, a distillation layer and a heating zone in sequence from top to bottom in the naphthalene purification distillation tower, a gas phase outlet is provided at the top of the naphthalene purification distillation tower, and a non-volatile matter outlet is provided at the bottom of the naphthalene purification distillation tower; a feed port is provided at the side of the naphthalene purification distillation tower, the feed port is located between the packing layer and the distillation layer, the feed port is connected to the naphthalene outlet of the naphthalene heater, so that the raw material naphthalene heated by the naphthalene heater enters the naphthalene purification distillation tower, the distillation layer is used to purify and separate the raw material naphthalene, the separated liquid phase enters the heating zone for heating and evaporation, the separated gas phase enters the packing layer, the liquid phase entrained in the gas phase is removed by the packing layer, the rising gas phase coming out of the packing layer enters the buffer zone to reduce the linear velocity, and further removes the liquid droplets entrained in the gas phase.

[0012] In an optional embodiment, the radial dimension of the area of ​​the naphthalene purification distillation tower located above the packing layer is larger than the radial dimension of the area where the packing layer is located and forms the buffer zone; a demister is provided in the buffer zone so that the gas phase entering the buffer zone can pass through the demister to further remove entrained droplets.

[0013] In an optional embodiment, a non-volatile matter return port is provided on the side of the naphthalene purification distillation tower near its bottom end, and the non-volatile matter return port is located below the heating zone; the non-volatile matter return port and the non-volatile matter outlet are connected by a non-volatile matter circulation pipeline, and a circulation pump is provided on the non-volatile matter circulation pipeline. The non-volatile matter in the bottom of the naphthalene purification distillation tower enters the non-volatile matter circulation pipeline under the action of the circulation pump and returns to the bottom of the naphthalene purification distillation tower through the non-volatile matter return port.

[0014] In an optional embodiment, an annular pipe is provided in the bottom of the naphthalene purification distillation tower, the annular pipe is located below the heating zone, and a spray hole is provided on the annular pipe. One end of the annular pipe is connected to the non-volatile matter return port so that the returned material first enters the annular pipe and is sprayed into the bottom of the tower through the spray hole on the annular pipe, thereby realizing dynamic flow of the tower bottom material and preventing high-temperature coking.

[0015] In an optional embodiment, the phthalic anhydride raw material industrial naphthalene purification feeding device also includes a naphthalene non-volatile matter tank and a naphthalene capture box; a drain pipe is connected to the non-volatile matter circulation pipeline between the circulation pump and the non-volatile matter return port, and the drain pipe is connected to the naphthalene non-volatile matter tank, and the top of the naphthalene non-volatile matter tank is connected to the naphthalene capture box through a naphthalene capture pipe.

[0016] In an optional embodiment, the naphthalene purification distillation tower is provided with a steam inlet and a steam outlet communicated with the heating zone, and the steam inlet is connected to a steam input pipe of a phthalic anhydride production device;

[0017] A heating tube bundle is provided in the heating zone of the naphthalene purification distillation tower, the upper port of the heating tube bundle is connected to the distillation layer, and the lower port of the heating tube bundle is connected to the tower kettle located below the heating zone. The heating tube bundle is used to heat and evaporate the liquid phase separated from the distillation layer.

[0018] In an optional embodiment, the industrial naphthalene purification feeding device for the phthalic anhydride raw material also includes an electric heater, the electric heater has a heating cavity, an electric heating component is arranged in the heating cavity, a liquid naphthalene inlet and a liquid naphthalene outlet respectively connected to the naphthalene purification distillation tower are provided on the heating cavity, the liquid naphthalene inlet is located above the liquid naphthalene outlet, so that the liquid phase separated by the distillation layer enters the heating cavity, is heated, and then returns to the bottom of the naphthalene purification distillation tower.

[0019] In an optional embodiment, the hot fluid side of the naphthalene heater is connected to the steam input pipe of the phthalic anhydride production device.

[0020] The utility model embodiment also provides a phthalic anhydride production device, which includes a mixer and a reactor connected to the mixer. The phthalic anhydride production device also includes the phthalic anhydride raw material industrial naphthalene purification feeding device in any of the above embodiments, and the gas phase outlet of the naphthalene purification distillation tower of the phthalic anhydride raw material industrial naphthalene purification feeding device is connected to the gas phase naphthalene inlet of the mixer for providing gas phase naphthalene to the mixer.

[0021] The phthalic anhydride production device further comprises an air filter, an air compressor and an air heater which are connected in sequence, wherein the air outlet of the air heater is connected to the air inlet of the mixer, so that the air is filtered by the air filter and then compressed by the air compressor, and the compressed air is heated by the air heater and then enters the mixer to be mixed with gas-phase naphthalene.

[0022] Compared with the prior art, the beneficial effects of the embodiments of the utility model are: reasonable design, simple structure, easy installation, and effective separation of liquid and entrained heavy components in the gas phase, preventing deposition in the gas phase pipeline and heating tube bundle, reducing the generation of reaction by-products, improving product quality, and extending the long-term operation of phthalic anhydride production. It overcomes the difficulty of cleaning the U-shaped heat exchange tube structure and the inability to discharge volatile components, and the inability to continuously discharge residues. Moreover, the utility model is provided with an electric heater, which is convenient and simple to start and stop, and can be started without introducing external steam.

[0023] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not intended to restrict the present invention.

[0024] The overview of various implementations or examples of the technology described in this utility model is not a comprehensive disclosure of the entire scope or all features of the disclosed technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In the drawings, which are not necessarily drawn to scale, the same reference numerals may describe similar components in different views. The drawings generally illustrate various embodiments by way of example and not limitation, and together with the description and claims, serve to illustrate the disclosed embodiments. When appropriate, the same reference numerals are used throughout the drawings to refer to the same or similar parts. Such embodiments are illustrative and are not intended to be exhaustive or exclusive embodiments of the present apparatus or method.

[0026] Figure 1 This is a schematic diagram of a device for purifying industrial naphthalene, a phthalic anhydride raw material, according to an embodiment of the utility model.

[0027] Reference numerals:

[0028] 1-naphthalene heater; 2-naphthalene outlet; 3-feed pipe; 4-naphthalene purification distillation tower; 41-feed port; 42-buffer zone; 43-packing layer; 44-distillation layer; 45-heating zone; 46-feed distributor; 47-heating tube bundle; 48-demister; 49-tower kettle; 5-non-volatile matter circulation pipeline; 6-circulation pump; 7-naphthalene non-volatile matter tank; 8-naphthalene capture box; 9-drain pipe; 10-steam input pipe; 11-electric heater; 12-electric heating component; 13-mixer; 14-air filter; 15-air compressor; 16-air heater; 17-medium-pressure steam; 18-naphthalene, air mixture pipeline; 19-vent pipe; 20-start-up liquid naphthalene circulation pipe. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the embodiment of the utility model clearer, the technical solution of the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings of the embodiment of the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model, not all of the embodiments. Based on the described embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0030] Unless otherwise defined, the technical terms or scientific terms used in the present invention shall have the usual meanings understood by persons with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "include" or "comprise" and the like mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" and the like are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0031] In order to keep the following description of the embodiments of the present invention clear and concise, the present invention omits detailed descriptions of known functions and known components.

[0032] The embodiment of the utility model provides a phthalic anhydride raw material industrial naphthalene purification feeding device, which is used to vaporize industrial naphthalene to improve the purity of naphthalene. The phthalic anhydride raw material industrial naphthalene purification feeding device is used in a phthalic anhydride production device, and is used to feed into a mixer 13 of the phthalic anhydride production device to provide the mixer 13 with naphthalene gas with higher purity.

[0033] like Figure 1 As shown, the phthalic anhydride raw material industrial naphthalene purification feeding device comprises a naphthalene heater 1 and a naphthalene purification distillation tower 4. The naphthalene inlet of the naphthalene heater 1 is connected to a feed pipe 3, through which industrial naphthalene is fed into the naphthalene heater 1, and the naphthalene heater 1 is used to heat the raw material naphthalene.

[0034] Continue to combine Figure 1, a buffer zone 42, a packing layer 43, a rectifying layer 44 and a heating zone 45 are sequentially arranged in the naphthalene purification rectifying tower 4 from top to bottom. A gas phase outlet is arranged at the top of the naphthalene purification rectifying tower 4, and a non-volatile matter outlet is arranged at the bottom of the naphthalene purification rectifying tower 4. A feed port 41 is arranged at the side of the naphthalene purification rectifying tower 4, and the feed port 41 is located between the packing layer 43 and the rectifying layer 44, and the feed port 41 is connected to the naphthalene outlet 2 of the naphthalene heater 1, so that the raw material naphthalene heated by the naphthalene heater 1 is sent between the packing layer 43 and the rectifying layer 44 in the naphthalene purification rectifying tower 4. A feed distributor 46 can be arranged between the packing layer 43 and the rectifying layer 44, and the feed distributor 46 is connected to the feed port 41, so that the raw material naphthalene is evenly distributed to the rectifying layer 44 through the feed distributor 46. The distillation layer 44 is used to purify and separate the raw material naphthalene. The separated liquid phase enters the heating zone 45 to continue heating and evaporation. The gas phase separated by the distillation layer 44 enters the packing layer 43. The liquid phase entrained in the gas phase is removed by the packing layer 43. The rising gas phase coming out of the packing layer 43 enters the buffer zone 42 to reduce the linear speed, so as to further remove the droplets entrained in the gas phase.

[0035] The phthalic anhydride raw material industrial naphthalene purification feeding device of the utility model embodiment improves the efficiency and effect of raw material naphthalene vaporization and purification through the naphthalene purification distillation tower 4 with a special structure, greatly improves the purity of industrial naphthalene, and reduces energy consumption.

[0036] In some embodiments, Figure 1 As shown, the radial dimension of the area above the packing layer 43 of the naphthalene purification distillation tower 4 is larger than the radial dimension of the area where the packing layer 43 is located and forms a buffer zone 42. The buffer zone 42 reduces the flow velocity of the gas phase by changing the diameter, and the structure is simple and reasonable, and the processing is convenient. A demister 48 is provided in the buffer zone 42, so that the gas phase entering the buffer zone 42 can further remove the entrained droplets through the demister 48, thereby improving the purity of the gas phase naphthalene.

[0037] The specific structural form of the demister 48 is not limited, and commonly used demisters in the prior art such as baffle demisters, swirl impeller demisters and double-block demisters may be used.

[0038] In some embodiments, a non-volatile matter return port is provided at the side of the naphthalene purification distillation tower 4 near its bottom end, and the non-volatile matter return port is located below the heating zone 45. The non-volatile matter return port and the non-volatile matter outlet are connected by a non-volatile matter circulation pipeline 5, and a circulation pump 6 is provided on the non-volatile matter circulation pipeline 5. The non-volatile matter in the tower bottom 49 of the naphthalene purification distillation tower 4 enters the non-volatile matter circulation pipeline 5 under the action of the circulation pump 6, and returns to the tower bottom 49 of the naphthalene purification distillation tower 4 through the non-volatile matter return port.

[0039] By providing a non-volatile component circulation pipeline 5 and a circulation pump 6, the mixture (including non-volatile components, heavy components and a small amount of liquid naphthalene) that is not evaporated and deposited in the tower bottom 49 of the naphthalene purification and distillation tower 4 can be first output and then returned to the tower bottom 49. The mixture in the tower bottom 49 is forced to circulate to prevent coking in the tower bottom 49 under high temperature static conditions, thereby ensuring the efficiency of evaporation and reducing the consumption of naphthalene in the evaporation process as much as possible.

[0040] An annular pipe (not shown) can be arranged in the tower kettle 49 of the naphthalene purification and rectification tower 4, the annular pipe is located below the heating zone 45, and a spray hole is arranged on the annular pipe, one end of the annular pipe is connected to the non-volatile component return port, so that the returned material first enters the annular pipe and is sprayed into the tower kettle 49 through the spray hole on the annular pipe. In this way, the mixture in the tower kettle 49 can be disturbed to play a stirring role, thereby preventing the material in the tower kettle 49 from coking under high temperature static conditions.

[0041] Continue to combine Figure 1 , the phthalic anhydride raw material industrial naphthalene purification feeding device also includes a naphthalene non-volatile component tank 7 and a naphthalene trapping box 8. A drain pipe 9 is connected to the non-volatile component circulation line 5 between the circulating pump 6 and the non-volatile component return port, and the drain pipe 9 is connected to the naphthalene non-volatile component tank 7, and the top of the naphthalene non-volatile component tank 7 is connected to the naphthalene trapping box 8 through the naphthalene trapping pipe. After the tower bottom 49 mixture is forced to circulate for a long time, the material in the non-volatile component circulation line 5 is detected, and the content of non-volatile component in the control material is less than or equal to 2%, when the non-volatile component in the material exceeds this content, the valve on the drain pipe 9 is opened, and part of the material of the tower bottom 49 is transported to the naphthalene non-volatile component tank 7 through the drain pipe 9, and the high-temperature gas generated in the naphthalene non-volatile component tank 7 is recovered through the naphthalene trapping box 8, and this high-temperature gas is mainly gas-phase naphthalene, which can be recycled.

[0042] A start-up liquid naphthalene circulation pipe 20 is connected to the pipeline between the gas phase outlet at the top of the naphthalene purification distillation tower 4 and the gas phase naphthalene inlet of the mixer 13, and the end of the start-up liquid naphthalene circulation pipe 20 is connected to the naphthalene non-volatile component tank 7, which is used to discharge the residual liquid phase naphthalene into the naphthalene non-volatile component tank 7 and to relieve the pressure of the pipeline.

[0043] The heating method of the naphthalene purification distillation tower 4 can be heating oil heating or steam heating, for example. The present embodiment shows that steam is used as a heat source for heating. Specifically, the naphthalene purification distillation tower 4 is provided with a steam inlet and a steam outlet connected to the heating zone 45, and the steam inlet is connected to the steam input pipe 10 of the phthalic anhydride production device. The by-product medium-pressure steam (medium-pressure steam pressure is 5.0MPa and temperature is 285°C) of the phthalic anhydride production device is utilized to heat industrial naphthalene, and the recycling of energy is achieved under the premise of ensuring the effective evaporation of industrial naphthalene.

[0044] like Figure 1As shown, a heating tube bundle 47 is provided in the heating zone 45 of the naphthalene purification distillation tower 4, the upper end of the heating tube bundle 47 is connected to the distillation layer 44, and the lower end of the heating tube bundle 47 is connected to the tower kettle 49 located below the heating zone 45, and the heating tube bundle 47 is used to heat and evaporate the liquid phase separated from the distillation layer 44. The heating tube bundle 47 is used to heat and evaporate the liquid naphthalene, and the structure is simple and reasonable.

[0045] Optional, continue combining Figure 1 , the phthalic anhydride raw material industrial naphthalene purification feeding device also includes an electric heater 11. The electric heater 11 has a heating cavity, an electric heating component 12 is arranged in the heating cavity, and a liquid naphthalene inlet and a liquid naphthalene outlet 2 are respectively connected to the naphthalene purification distillation tower 4 on the heating cavity, and the liquid naphthalene inlet is located above the liquid naphthalene outlet 2, so that the liquid phase separated by the distillation layer 44 enters the heating cavity and is heated and then returns to the tower bottom 49 of the naphthalene purification distillation tower 4. By arranging the electric heater 11, the liquid naphthalene can be heated and evaporated when the phthalic anhydride production device is not started and does not generate steam, and the disadvantage of introducing steam from the outside to start the operation can be avoided. When the phthalic anhydride production device is started, the by-product steam enters the heating tube bundle 47 through the steam input pipe 10, and the liquid naphthalene is heated and vaporized, and the electric heater 11 is slowly cut off.

[0046] The utility model does not specifically limit the heat exchange medium of the naphthalene heater 1, which can be selected and determined according to actual needs. In this embodiment, the hot fluid side of the naphthalene heater 1 is connected to the steam input pipe 10 of the phthalic anhydride production device, so that the by-product medium-pressure steam of the phthalic anhydride production device is used as the heat source of the naphthalene heater 1, thereby realizing the effective utilization of the by-product steam of the phthalic anhydride production device. The pressure of the by-product steam is 5.0MPa and the temperature is 285°C.

[0047] It can be understood that valves are provided on each pipeline of the phthalic anhydride raw material industrial naphthalene purification feeding device of the embodiment of the utility model, so as to control the cutting off and conducting of the pipeline as needed.

[0048] The utility model embodiment also provides a phthalic anhydride production device, the phthalic anhydride production device includes a mixer 13 and a reactor (not shown) connected to the mixer 13, the phthalic anhydride production device also includes the phthalic anhydride raw material industrial naphthalene purification feeding device in any of the above embodiments, the gas phase outlet of the naphthalene purification distillation tower 4 of the phthalic anhydride raw material industrial naphthalene purification feeding device is connected to the gas phase naphthalene inlet of the mixer 13, and is used to provide gas phase naphthalene to the mixer 13. The phthalic anhydride production device of this embodiment can reduce the generation of reaction by-products, improve product quality, and extend the long-term operation of phthalic anhydride production due to the high purity of gas phase naphthalene.

[0049] In some embodiments, the phthalic anhydride production device further comprises an air filter 14, an air compressor 15 and an air heater 16 which are connected in sequence. The air outlet of the air heater 16 is connected to the air inlet of the mixer 13, so that the air is filtered by the air filter 14 and then compressed by the air compressor 15, and the compressed air is heated by the air heater 16 and then enters the mixer 13 to mix with gas-phase naphthalene. That is, the air required for the phthalic anhydride production device for preparing phthalic anhydride by naphthalene oxidation is supplied by the atmosphere, filtered by the air filter 14, compressed to 60Kpa by the air compressor 15, and the compressed air is heated to 185-200°C by the medium-pressure steam 17 by the air heater 16 before entering the mixer 13.

[0050] A vent pipe 19 may be provided on the pipeline between the air compressor 15 and the air heater 16 .

[0051] The gas phase coming out from the gas phase outlet at the top of the naphthalene purification and rectification tower 4, i.e. naphthalene steam, is sent into a mixer 13 and fully mixed with air before going to the reactor through a naphthalene-air mixture pipeline 18, wherein the flow rate of the naphthalene steam entering the mixer 13 is automatically regulated by a naphthalene steam flow control valve so that the flow rate of the naphthalene steam is kept at a set flow rate.

[0052] The naphthalene and air mixture coming out of the mixer 13 enters the reactor at a temperature of about 180-220°C. The mixed gas enters from the top of the reactor. On the surface of the V-Ti catalyst, naphthalene is oxidized by air to generate phthalic anhydride. This reaction is a highly exothermic reaction within the explosion range. Most of the reaction heat is removed through the molten salt circulating in the molten salt cooler, and 5.0MPa high-pressure saturated steam is generated through the high-pressure steam drum. It is sent to the naphthalene purification distillation tower 4 through the steam input pipe 10 for naphthalene vaporization heating steam, and the excess steam is used for refining or external delivery.

[0053] The 360-380°C reaction gas in the reactor is discharged from the bottom of the reactor, cooled to 170-175°C by a gas cooler, and then enters a phthalic anhydride switching condenser, which condenses high-quality crude phthalic anhydride for refining treatment.

[0054] The reaction principle of naphthalene oxidation to produce phthalic anhydride is as follows:

[0055] After industrial naphthalene is vaporized, it is mixed with pressurized air (oxygen content 21%) in a certain proportion and then enters a reactor loaded with a catalyst. At a certain temperature, the main reaction occurs on the catalyst surface to produce phthalic anhydride, and the side reaction produces maleic anhydride, benzoic acid, naphthoquinone and other by-products. A small amount of peroxidation produces CO2 and CO. The reaction that occurs during oxidation is a highly exothermic reaction.

[0056] The reaction process of preparing phthalic anhydride by gas phase catalytic oxidation using naphthalene as raw material includes a series of parallel and series reactions.

[0057] Main reaction:

[0058]

[0059] Naphthalene Phthalic Anhydride

[0060] Main side effects:

[0061]

[0062] Maleic anhydride

[0063] Naphthoquinone

[0064]

[0065] The oxidation of naphthalene starts with the donation of [O], and then the steps of dehydrogenation and bond cleavage are easy to carry out. Phthalic anhydride and naphthoquinone are basically generated in parallel, and CO2 and CO are mainly sequential reaction products. Naphthoquinone is the most unstable, and its oxidation rate is 4 times that of naphthalene, 133 times that of phthalic anhydride, and 6 times that of maleic anhydride. 50%-75% of the naphthoquinone generated in the reaction is converted into phthalic anhydride, and 25%-50% is converted into maleic anhydride. The further reaction rate of phthalic anhydride is the lowest, especially when naphthalene and naphthoquinone are still present in the gas phase, the possibility of further oxidation and decomposition of phthalic anhydride is very small.

[0066] The reaction mechanism is shown below:

[0067]

[0068] In order to generate more target product phthalic anhydride, during the reaction process, we should try to select the reaction process of steps 1, 2, and 3, and suppress the reaction process of steps 4, 5, and 6. This requires not only a good catalyst, but also strict control of the air volume, feed amount, hot spot temperature, and molten salt temperature during the production process to obtain the highest phthalic anhydride yield.

[0069]

[0070] Naphthalene reaction mechanism diagram

[0071] The beneficial effects of the utility model are:

[0072] 1. The purity of industrial naphthalene is greatly improved, which improves the heating efficiency;

[0073] 2. It is easy to start and stop, and can be started without introducing external steam;

[0074] 3. Ensure the naphthalene purity separation and vaporization effect of the naphthalene purification distillation tower, improve the efficiency and effect of raw material naphthalene vaporization, and reduce energy consumption;

[0075] 4. Improve and enhance the quality of phthalic anhydride products to ensure high-load, long-cycle, stable and safe operation of the catalyst.

[0076] The above description is intended to be illustrative rather than restrictive, and those skilled in the art may make changes, modifications, substitutions and variations to the above embodiments within the scope of the present disclosure. Moreover, the above examples (or one or more of them) may be used in combination with each other, and it is contemplated that these embodiments may be combined with each other in various combinations or permutations.

Claims

1. A phthalic anhydride raw material industrial naphthalene purification feeding device, characterized in that, include: A naphthalene heater, wherein a naphthalene inlet of the naphthalene heater is connected to a feed pipe, and the naphthalene heater is used to heat the raw material naphthalene; A naphthalene purification distillation tower is provided with a buffer zone, a packing layer, a distillation layer and a heating zone in sequence from top to bottom in the naphthalene purification distillation tower, a gas phase outlet is provided at the top of the naphthalene purification distillation tower, and a non-volatile matter outlet is provided at the bottom of the naphthalene purification distillation tower; a feed port is provided at the side of the naphthalene purification distillation tower, the feed port is located between the packing layer and the distillation layer, the feed port is connected to the naphthalene outlet of the naphthalene heater, so that the raw material naphthalene heated by the naphthalene heater enters the naphthalene purification distillation tower, the distillation layer is used to purify and separate the raw material naphthalene, the separated liquid phase enters the heating zone for heating and evaporation, the separated gas phase enters the packing layer, the liquid phase entrained in the gas phase is removed by the packing layer, the rising gas phase coming out of the packing layer enters the buffer zone to reduce the linear velocity, and further removes the liquid droplets entrained in the gas phase.

2. The phthalic anhydride raw material industrial naphthalene purification feeding device according to claim 1, characterized in that, The radial dimension of the area of ​​the naphthalene purification distillation tower located above the packing layer is larger than the radial dimension of the area where the packing layer is located and forms the buffer zone; a demister is provided in the buffer zone so that the gas phase entering the buffer zone can pass through the demister to further remove entrained droplets.

3. The phthalic anhydride raw material industrial naphthalene purification feeding device according to claim 1, characterized in that, A non-volatile matter return port is provided at the side of the naphthalene purification distillation tower near its bottom end, and the non-volatile matter return port is located below the heating zone; the non-volatile matter return port and the non-volatile matter outlet are connected through a non-volatile matter circulation pipeline, and a circulation pump is provided on the non-volatile matter circulation pipeline. The non-volatile matter in the bottom of the naphthalene purification distillation tower enters the non-volatile matter circulation pipeline under the action of the circulation pump and returns to the bottom of the naphthalene purification distillation tower through the non-volatile matter return port.

4. The phthalic anhydride raw material industrial naphthalene purification feeding device according to claim 3, characterized in that, An annular pipe is provided in the tower kettle of the naphthalene purification distillation tower, the annular pipe is located below the heating zone, and a spray hole is provided on the annular pipe. One end of the annular pipe is connected to the non-volatile component return port so that the returned material first enters the annular pipe and is sprayed into the tower kettle through the spray hole on the annular pipe.

5. The phthalic anhydride raw material industrial naphthalene purification feeding device according to claim 3 is characterized in that, The phthalic anhydride raw material industrial naphthalene purification feeding device also includes a naphthalene non-volatile component tank and a naphthalene capture box; a drain pipe is connected to the non-volatile component circulation pipeline between the circulation pump and the non-volatile component return port, the drain pipe is connected to the naphthalene non-volatile component tank, and the top of the naphthalene non-volatile component tank is connected to the naphthalene capture box through a naphthalene capture pipe.

6. The phthalic anhydride raw material industrial naphthalene purification feeding device according to claim 1 is characterized in that, The naphthalene purification distillation tower is provided with a steam inlet and a steam outlet communicated with the heating zone, and the steam inlet is connected to the steam input pipe of the phthalic anhydride production device; A heating tube bundle is provided in the heating zone of the naphthalene purification distillation tower, the upper port of the heating tube bundle is connected to the distillation layer, and the lower port of the heating tube bundle is connected to the tower kettle located below the heating zone. The heating tube bundle is used to heat and evaporate the liquid phase separated from the distillation layer.

7. The phthalic anhydride raw material industrial naphthalene purification feeding device according to claim 1 is characterized in that, The phthalic anhydride raw material industrial naphthalene purification feeding device also includes an electric heater, which has a heating cavity. The heating cavity is provided with an electric heating component. The heating cavity is provided with a liquid naphthalene inlet and a liquid naphthalene outlet respectively connected to the naphthalene purification distillation tower. The liquid naphthalene inlet is located above the liquid naphthalene outlet, so that the liquid phase separated by the distillation layer enters the heating cavity, is heated, and then returns to the bottom of the naphthalene purification distillation tower.

8. The phthalic anhydride raw material industrial naphthalene purification feeding device according to claim 1 is characterized in that, The hot fluid side of the naphthalene heater is connected to the steam input pipe of the phthalic anhydride production device.

9. A phthalic anhydride production device, comprising a mixer and a reactor connected to the mixer, characterized in that: The phthalic anhydride production device also includes the phthalic anhydride raw material industrial naphthalene purification feeding device according to any one of claims 1 to 8, wherein the gas phase outlet of the naphthalene purification distillation tower of the phthalic anhydride raw material industrial naphthalene purification feeding device is connected to the gas phase naphthalene inlet of the mixer for providing gas phase naphthalene to the mixer.

10. The phthalic anhydride production device according to claim 9, characterized in that: The phthalic anhydride production device also includes an air filter, an air compressor and an air heater which are connected in sequence. The air outlet of the air heater is connected to the air inlet of the mixer so that the air is filtered by the air filter and then compressed by the air compressor. The compressed air is heated by the air heater and then enters the mixer to be mixed with gaseous naphthalene.

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