Phthalic anhydride preparation device with preheater

Abstract

The utility model discloses a phthalic anhydride preparation device with a preheater, which comprises an o-xylene storage tank, an o-xylene heater, a mixer, an oxidation reactor, a first phthalic anhydride catcher, a second phthalic anhydride catcher, a tail gas tower and a phthalic anhydride rectifying tower which are sequentially connected through a pipeline, a liquid adding pump is arranged between the o-xylene storage tank and the o-xylene heater; the phthalic anhydride preparation device with the preheater further comprises an air compressor and an air heater which are sequentially connected through a pipeline, the air heater is connected with the mixer through a pipeline, and the air preheater is further arranged between the air compressor and the air heater and comprises a body. A heating pipe fitting is arranged in the body, the heating pipe fitting comprises a heating pipe and spiral fins arranged around the heating pipe, by-product low-pressure steam of the oxidation reactor can be reasonably utilized by additionally arranging the air preheater, and the use amount of high-pressure steam is saved.

Description

Technical Field

[0001] The utility model relates to the technical field of chemical equipment, in particular to a phthalic anhydride preparation device with a preheater. Background Art

[0002] Phthalic anhydride, short for phthalic anhydride, is an important organic synthesis intermediate and a fundamental organic raw material for the synthesis of polyester fibers, alkyd resins, plasticizers, dyes, and pharmaceuticals. The raw materials for phthalic anhydride production are naphthalene and o-xylene. Currently, the main production route for phthalic anhydride in my country is through the air oxidation of o-xylene at 380-480°C using catalysts such as vanadium oxide, antimony oxide, potassium oxide, and sulfur trioxide. Therefore, the air must be heated to 200-250°C before entering the oxidation reactor. The air is then mixed with the heated o-xylene, vaporized, and then passed into the oxidation reactor for the oxidation reaction. The air is heated using an air heater, currently using high-pressure steam at a pressure of 4.0 MPa. However, the oxidation of o-xylene with air is an exothermic reaction, and the resulting byproduct, low-pressure steam at a pressure of 1.0 MPa, is not effectively utilized in production, resulting in resource waste. Utility Model Content

[0003] In view of this, the utility model provides a phthalic anhydride preparation device with a preheater, which can utilize the low-pressure steam with a pressure of 1.0 MPa produced as a by-product of the oxidation reactor.

[0004] The technical solution adopted by the utility model to solve its technical problems is:

[0005] A phthalic anhydride preparation device with a preheater comprises an o-xylene storage tank, an o-xylene heater, a mixer, an oxidation reactor, a first phthalic anhydride trap, a second phthalic anhydride trap, a tail gas tower, and a phthalic anhydride distillation tower, which are sequentially connected via pipelines. A liquid adding pump is provided between the o-xylene storage tank and the o-xylene heater. The phthalic anhydride preparation device with a preheater also comprises an air compressor and an air heater, which are sequentially connected via pipelines. The air heater is connected to the mixer via pipelines. An air preheater is further provided between the air compressor and the air heater. The air preheater comprises a body, a heating pipe is provided inside the body, and the heating pipe comprises a heating pipe and spiral fins arranged around the heating pipe.

[0006] Furthermore, a first air inlet pipeline is provided above one end of the side wall of the air preheater, and a first air outlet pipeline is provided below the other end of the side wall. Both ends of the air preheater are provided with heads, a low-pressure steam outlet pipeline is provided at the head close to the air compressor, and a low-pressure steam inlet pipeline is provided at the head away from the air compressor.

[0007] Furthermore, the upper part of one end of the side wall of the air heater is connected to the first air outlet pipeline, and the lower part of the other end of the side wall is provided with a second air outlet pipeline. The air preheater is provided with a head at both ends, and a high-pressure steam outlet pipeline is provided at the head close to the air preheater, and a high-pressure steam inlet pipeline is provided at the head away from the air preheater.

[0008] Furthermore, a first thermometer is provided on the first air outlet pipeline, and the first thermometer is provided with an upper limit and a lower limit, and a first solenoid valve is provided on the low-pressure steam inlet pipeline.

[0009] Furthermore, a second thermometer is provided on the second air outlet pipeline, and the second thermometer is provided with upper and lower limits, and a second solenoid valve is provided on the high-pressure steam inlet pipeline.

[0010] Furthermore, the first output end of the first thermometer is electrically connected to the first input end of the first solenoid valve, the second output end of the first thermometer is electrically connected to the first input end of the second solenoid valve, the first output end of the second thermometer is electrically connected to the second input end of the first solenoid valve, and the second output end of the second thermometer is electrically connected to the second input end of the second solenoid valve.

[0011] Furthermore, the air preheater includes a main body, and a first air inlet and a first air outlet are respectively provided on both sides of the main body near the two ends. Several heating pipes are provided inside the air preheater body, and a first fixing plate and a second fixing plate are respectively provided at both ends of the heating pipes.

[0012] Furthermore, a semicircular first head and a second head are respectively provided at both ends of the air preheater body, the first head is provided with a low-pressure steam outlet, the second head is provided with a low-pressure steam inlet, and the heating pipe is connected to the first head through the first fixed plate and is connected to the second head through the second fixed plate.

[0013] Furthermore, reinforcing ribs are provided between adjacent pitches of the fins.

[0014] Furthermore, the reinforcing ribs are arranged in multiple rows, and each row is arranged on the same straight line or staggered.

[0015] The beneficial effects of the utility model are:

[0016] The utility model provides a phthalic anhydride preparation device with a preheater, which comprises an o-xylene storage tank, an o-xylene heater, a mixer, an oxidation reactor, a first phthalic anhydride trap, a second phthalic anhydride trap, a tail gas tower and a phthalic anhydride distillation tower, which are connected in sequence through pipelines. A liquid adding pump is provided between the o-xylene storage tank and the o-xylene heater. The phthalic anhydride preparation device with a preheater also comprises an air compressor and an air heater, which are connected in sequence through pipelines. The air heater is connected to the mixer through the pipeline. An air preheater is further provided between the air compressor and the air heater. The air preheater comprises a main body, and a heating pipe fitting is provided inside the main body. By adding the air preheater, low-pressure steam produced as a by-product of the oxidation reactor can be reasonably utilized, thereby saving the use of high-pressure steam. By arranging spiral fins around the heating pipe of the heating pipe fitting, the heating effect can be increased, thereby further reducing the use of high-pressure steam. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0018] Figure 1 This is a schematic diagram of a phthalic anhydride preparation device with a preheater according to the present invention;

[0019] Figure 2 for Figure 1 The structural diagram of the air preheater shown in ;

[0020] Figure 3 for Figure 2 Sectional view along AA;

[0021] Figure 4 for Figure 1 Another structural schematic diagram of the air preheater shown in ;

[0022] Figure 5 for Figure 4 Cross-sectional view along BB;

[0023] Figure 6 This is a schematic diagram of the heating pipe structure in the utility model;

[0024] In the figure: 100, phthalic anhydride preparation device with preheater; 1, o-xylene storage tank; 2, o-xylene heater; 3, mixer; 4, air preheater; 5, air preheater; 51, first air inlet pipeline; 52, first air outlet pipeline; 521, first thermometer; 53, low-pressure steam inlet pipeline; 531, first solenoid valve; 54, low-pressure steam outlet pipeline; 55, body; 551, first fixing plate; 552, second fixing plate; 553, first air inlet; 554; first air outlet; 5 55. Heating pipe fittings; 5551. Heating pipes; 5552. Fins; 5553. Reinforcing ribs; 56. First end cap; 561. Low-pressure steam outlet; 57. Second end cap; 571. Low-pressure steam inlet; 6. Air heater; 61. Second air outlet pipeline; 611. Second thermometer; 62. High-pressure air inlet pipeline; 621. Second solenoid valve; 63. High-pressure steam outlet pipeline; 7. Oxidation reactor; 8. First phthalic anhydride trap; 9. Second phthalic anhydride trap; 10. Tail gas tower; 11. Phthalic anhydride distillation tower. DETAILED DESCRIPTION

[0025] The present invention will now be described in detail with reference to the accompanying drawings. This drawing is a simplified schematic diagram, which only illustrates the basic structure of the present invention in a schematic manner, and therefore only shows the components related to the present invention.

[0026] like Figure 1 As shown, the utility model provides a phthalic anhydride preparation device 100 with a preheater, comprising an o-xylene storage tank 1, an o-xylene heater 2, a mixer 3, an oxidation reactor 7, a first phthalic anhydride trap 8, a second phthalic anhydride trap 9, a tail gas tower 10 and a phthalic anhydride distillation tower 11 connected in sequence through pipelines, a liquid adding pump 11 is provided between the o-xylene storage tank 1 and the o-xylene heater 2, which can transport the o-xylene in the o-xylene storage tank 1 to the o-xylene heater; the phthalic anhydride preparation device 100 with a preheater also includes an air compressor 4 connected in sequence through pipelines , an air preheater 5, and an air heater 6. The air heater 6 is connected to the mixer 3 through a pipeline. The o-xylene and air are fully mixed in the mixer 3 before entering the oxidation reactor 7. After the reaction in the oxidation reactor 7 is completed, the o-xylene and air enter the first phthalic anhydride trap 8 from the bottom. The liquefied phthalic anhydride enters the phthalic anhydride distillation tower 11 from the bottom of the first phthalic anhydride trap 8, and the unliquefied phthalic anhydride-containing gas enters the second phthalic anhydride trap 9. The phthalic anhydride after further liquefaction enters the phthalic anhydride distillation tower 11 from the bottom of the second phthalic anhydride trap 9, and the unliquefied gas enters the tail gas tower 10 from the top of the second phthalic anhydride trap 9.

[0027] The heating medium of the air preheater 5 is low-pressure steam with a pressure of 1.0 MPa. A first air inlet pipeline 51 is provided above one end of the side wall of the air preheater 5, and a first air outlet pipeline 52 is provided below the other end of the side wall. Both ends of the air preheater 5 are provided with heads. The head close to the air compressor 4 is provided with a low-pressure steam outlet pipeline 54, and the head away from the air compressor 4 is provided with a low-pressure steam inlet pipeline 53. The purified air enters the air preheater 5 through the first air inlet pipeline 51, and the temperature can be heated to about 120°C through the air preheater 5. The preheated air enters the air heater 6 through the first air outlet pipeline 52. The heating medium of the air heater 6 is high-pressure steam at a pressure of 4.0 MPa. The upper end of one sidewall is connected to the first air outlet pipeline 52, and the lower end of the other sidewall is provided with a second air outlet pipeline 61. The air preheater 6 is provided with end caps at both ends. The end cap near the air preheater 5 is provided with a high-pressure steam outlet pipeline 63, and the end cap away from the air preheater 5 is provided with a high-pressure steam inlet pipeline 62. The preheated air enters the air heater 6 through the first air outlet pipeline 52. After being heated to approximately 250°C, it enters the mixer 3, mixes with o-xylene, and then enters the oxidation reactor 7.

[0028] Preferably, the first air outlet pipeline 52 is provided with a first thermometer 521, which is set with upper and lower limits, and the low-pressure steam inlet pipeline 53 is provided with a first solenoid valve 531. The second air outlet pipeline 61 is provided with a second thermometer 611, which is set with upper and lower limits, and the high-pressure steam inlet pipeline 62 is provided with a second solenoid valve 621. The first output end of the first thermometer 521 is electrically connected to the first input end of the first solenoid valve 531, the second output end of the first thermometer 521 is electrically connected to the first input end of the second solenoid valve 621, the first output end of the second thermometer 611 is electrically connected to the second input end of the first solenoid valve 531, and the second output end of the second thermometer 611 is electrically connected to the second input end of the second solenoid valve 621. The first solenoid valve 531 and the second solenoid valve 621 can flexibly control the flow of low-pressure steam and high-pressure steam according to the measurement data of the first thermometer 521 and the second thermometer 611 in coordination with each other's upper and lower limits, thereby reducing the amount of high-pressure steam while ensuring the temperature of the air entering the mixer 3.

[0029] like Figures 2 to 5As shown, the air preheater includes a cylindrical body 55, and a first air inlet 553 and a first air outlet 554 are respectively provided on both sides of the body 55 near both ends. A number of heating pipes 555 are provided inside the air preheater body 55, and a first fixing plate 551 and a second fixing plate 552 are respectively provided at both ends of the heating pipe 555. A semicircular first head 56 and a second head 57 are respectively provided at both ends of the air preheater body 55. A low-pressure steam outlet 561 is provided on the first head 56, and a low-pressure steam inlet 571 is provided on the second head 57. The heating pipe 555 passes through the first fixing plate 551 to communicate with the first head 56, and passes through the second fixing plate 552 to communicate with the second head 57. Low-pressure steam enters the second head 57 from the low-pressure steam inlet 571, enters the first head after heat transfer through the heating pipe 555, and then enters the low-pressure steam circuit through the low-pressure steam outlet 561. The purified air enters the heater body 555 through the first air inlet 553 , is heated by the heating pipe 555 , and then leaves the heater body 555 through the first air outlet 554 and enters the air heater 6 .

[0030] The structure of the air heater 6 is the same as that of the air preheater 5, and will not be repeated here.

[0031] like Figure 6 As shown, the heating tube 555 includes a cylindrical heating tube 5551, the outer circumference of which is provided with spiral fins 5552. The fins 5552 not only disturb the passing air, heating it evenly, but also increase the heat dissipation area of ​​the heating tube 555, thereby enhancing the heating effect. Reinforcing ribs 5553 are provided between adjacent pitches of the fins 5552. Specifically, the reinforcing ribs 5553 can be arranged in a straight line or staggered. Depending on the size of the fins 5552, multiple rows of reinforcing ribs 5553 can be provided.

[0032] The phthalic anhydride preparation device with a preheater provided by the utility model can reduce the amount of high-pressure steam used by adding an air preheater 5 in front of the air heater 6 and arranging spiral fins 5552 around the outside of the heating tube 5551, thereby rationally utilizing the low-pressure steam generated by the device itself. According to calculations, the phthalic anhydride preparation device with a preheater provided by the utility model can save more than 1 ton of high-pressure steam per hour.

[0033] Based on the above-mentioned ideal embodiment of the present invention, and in accordance with the above description, relevant personnel can make various changes and modifications without departing from the scope of the present invention. The technical scope of this utility model is not limited to the content of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A phthalic anhydride production device with a preheater, comprising an o-xylene storage tank, an o-xylene heater, a mixer, an oxidation reactor, a first phthalic anhydride trap, a second phthalic anhydride trap, a tail gas tower, and a phthalic anhydride distillation tower, which are sequentially connected through pipelines, wherein a liquid adding pump is provided between the o-xylene storage tank and the o-xylene heater; the phthalic anhydride production device with a preheater further comprises an air compressor and an air heater, which are sequentially connected through pipelines, wherein the air heater is connected to the mixer through a pipeline, wherein: An air preheater is further provided between the air compressor and the air heater. The air preheater comprises a main body. A heating pipe is provided inside the main body. The heating pipe comprises a heating pipe and spiral fins arranged around the heating pipe.

2. The phthalic anhydride preparation device with a preheater according to claim 1, wherein A first air inlet pipeline is provided above one end of the side wall of the air preheater, and a first air outlet pipeline is provided below the other end of the side wall. Heads are provided at both ends of the air preheater. A low-pressure steam outlet pipeline is provided at the head close to the air compressor, and a low-pressure steam inlet pipeline is provided at the head away from the air compressor.

3. The phthalic anhydride preparation device with a preheater according to claim 2, wherein The upper part of one end of the side wall of the air heater is connected to the first air outlet pipeline, and the lower part of the other end of the side wall is provided with a second air outlet pipeline. Both ends of the air preheater are provided with heads. The head close to the air preheater is provided with a high-pressure steam outlet pipeline, and the head away from the air preheater is provided with a high-pressure steam inlet pipeline.

4. The phthalic anhydride preparation device with a preheater according to claim 3, wherein The first air outlet pipeline is provided with a first thermometer, which has upper and lower limits. The low-pressure steam inlet pipeline is provided with a first solenoid valve.

5. The phthalic anhydride preparation device with a preheater according to claim 4, wherein The second air outlet pipeline is provided with a second thermometer, which is provided with upper and lower limits, and the high-pressure steam inlet pipeline is provided with a second solenoid valve.

6. The phthalic anhydride preparation device with a preheater according to claim 5, wherein The first output end of the first thermometer is electrically connected to the first input end of the first solenoid valve, the second output end of the first thermometer is electrically connected to the first input end of the second solenoid valve, the first output end of the second thermometer is electrically connected to the second input end of the first solenoid valve, and the second output end of the second thermometer is electrically connected to the second input end of the second solenoid valve.

7. The phthalic anhydride preparation device with a preheater according to claim 1, wherein The air preheater includes a body, and a first air inlet and a first air outlet are respectively provided on both sides of the body near the two ends. A plurality of heating pipes are provided inside the air preheater body, and a first fixing plate and a second fixing plate are respectively provided at both ends of the heating pipes.

8. The phthalic anhydride preparation device with a preheater according to claim 7, wherein The air preheater body is provided with a semicircular first head and a second head at both ends respectively. The first head is provided with a low-pressure steam outlet, and the second head is provided with a low-pressure steam inlet. The heating pipe is connected to the first head through the first fixed plate and is connected to the second head through the second fixed plate.

9. The phthalic anhydride preparation device with a preheater according to claim 1, wherein Reinforcing ribs are provided between adjacent pitches of the fins.

10. The phthalic anhydride preparation device with a preheater according to claim 9, characterized in that The reinforcing ribs are arranged in multiple rows, and each row is arranged on the same straight line or staggered.

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