A method and device for producing aromatic compounds

Abstract

The invention discloses a production method of aromatic compounds, which uses ethylene tar as a raw material, and the raw material is heated by a preheater and enters a decoking tower and a light-removing tower to remove a heavy phase, and the oil phase at the bottom of the light-removing tower enters an industrial naphthalene tower for vacuum distillation, and the top of the tower outputs industrial naphthalene products, and the heavy phase at the bottom of the tower is vacuum distilled in a demethylnaphthalene tower, and the top of the tower outputs medium-quality tar, and mixed methylnaphthalene is produced from the side of the tower, and the heavy phase at the bottom of the tower is mixed with the heavy phase at the bottom of the decoking tower and enters a downstream system. The invention uses vacuum distillation multiple towers in series to separate high-value-added aromatic compound series products, so that the purity of industrial naphthalene reaches more than 95%, and the purity of mixed methylnaphthalene reaches more than 80%, forming a highly efficient technical method for preparing aromatic compound series products from ethylene tar.

Description

Technical Field

[0001] The invention relates to the field of resource utilization of inferior oil products, and in particular to a production method and device for aromatic compounds. Background Art

[0002] Ethylene tar is a high-temperature condensation product of cracking raw materials during steam cracking. Its composition and output vary with different ethylene cracking raw materials and cracking conditions. The output is about 10%-15% of ethylene output. With the rapid development of China's ethylene industry, the output of ethylene tar has also increased rapidly. At present, the by-product ethylene tar of domestic ethylene plants has reached 4 million tons / year. How to fully and reasonably utilize ethylene by-product oil to produce the best economic benefits will have a significant impact on the overall benefits of ethylene and the deep processing of ethylene by-product resources. It is also one of the important issues that petrochemical companies at home and abroad are currently facing.

[0003] Industrial naphthalene is an important basic organic chemical raw material, mainly used for the synthesis of chemical products such as phthalic anhydride, naphthoquinone, naphthol, naphthalenesulfonic acid, naphthylamine, 2,6-dialkylnaphthalene, 2,6-naphthalenedicarboxylic acid, polyethylene naphthalate (PEN) and H acid. By the end of 2021, the production capacity of industrial naphthalene will be 1.31 million tons, and the market demand will remain basically the same in the next few years. In 2022, the price of industrial naphthalene will remain at around 6,000 yuan / ton.

[0004] α-Methylnaphthalene and β-methylnaphthalene are important raw materials for fine chemicals and organic chemicals with a wide range of uses. β-Methylnaphthalene is mainly used to produce vitamin K, pesticides, dyes, etc. α-Methylnaphthalene is used as a surfactant, heat carrier, pharmaceutical intermediate, and sulfur extractant for vinyl chloride fiber and polyester printing and dyeing carriers. It can also be used to produce plasticizers and fiber dyeing aids. At present, from the perspective of domestic and foreign markets, the annual demand for methylnaphthalene is 350,000 tons. Based on the current growth rate, it will continue to grow to 610,000 tons in the next five years.

[0005] At present, there are reports on comprehensive utilization methods of ethylene tar in the prior art, such as CN200810228387.0, CN201210442629.2, CN201310078652.2, CN201711349795.7, CN201810529519.7, etc.

[0006] Most of the ethylene tar processing technologies described in the above patents are to separate the light fraction of ethylene tar through a hydrorefining process to obtain naphthalene and methylnaphthalene products, which are complex processes, and the investment cost and energy consumption are relatively high. This process only produces naphthalene and methylnaphthalene products through a vacuum series distillation process, which is simple, has low investment cost and energy consumption, and has high economic value. Summary of the invention

[0007] Purpose of the invention: The technical problem to be solved by the present invention is to provide a method and device for producing aromatic compounds in view of the defects of the prior art such as low and insufficient utilization of heavy tar, which has the advantages of a wide range of raw materials, simple process, low equipment investment, safe operation, high product yield, etc., and can be directly used to produce industrial naphthalene, mixed methyl naphthalene, medium tar and other aromatic compounds through the method and system.

[0008] To achieve the above object, the present invention provides a method for producing aromatic compounds, comprising the following steps:

[0009] (1) Ethylene tar is used as raw material. The raw material is heated in a preheater and then enters a decoking tower. A forced circulation reboiler 1 is provided at the bottom of the decoking tower. After being processed in the decoking tower, the light components at the top of the tower enter the light removal tower, and the components at the bottom of the tower are sent to the downstream device.

[0010] The decompression operation of the light-removing tower is carried out, and a forced circulation reboiler 2 is installed in the tower bottom. The top gas of the tower enters the buffer tank 1 after being cooled by the light-removing tower condenser. The top of the buffer tank 1 is connected to the vacuum pump P4 to extract the non-condensable gas. The oil phase of the buffer tank 1 is pumped out by the light-removing tower light phase extraction pump P5, part of which goes to the downstream device, and part of which is refluxed to the light-removing tower C2; the heavy components at the bottom of the light-removing tower C2 are partly refluxed to the decoking tower C1 through the light-removing tower kettle extraction pump P6, and part of which is sent to the industrial naphthalene tower C3;

[0011] (2) The industrial naphthalene tower C3 is operated under reduced pressure, and a forced circulation reboiler 3 is provided in the tower bottom. The top gas is cooled by the condenser 2 and enters the buffer tank 2. The top of the buffer tank 2 is connected to a vacuum pump P8 to extract the non-condensable gas. The components in the buffer tank 2 are partly refluxed by the reflux pump P9, and partly sent out as industrial naphthalene products. The heavy components at the bottom of the industrial naphthalene tower C3 are sent to the methyl naphthalene tower C4 by the industrial naphthalene tower bottom pump P10;

[0012] (3) The methylnaphthalene tower C4 is operated under reduced pressure, and a forced circulation reboiler 4 is installed in the tower bottom. The light components at the top of the tower are cooled by the methylnaphthalene tower top condenser E7 and then enter the buffer tank 3. The top of the buffer tank 3 is connected to the vacuum pump P12 to extract the non-condensable gas. The components in the buffer tank 3 are partly refluxed through the reflux pump P13, and partly sent out as a medium-quality tar product. The methylnaphthalene product is extracted from the methylnaphthalene tower C4 side line. The heavy components at the bottom of the methylnaphthalene tower C4 are pumped out through the methylnaphthalene tower kettle pump P14 and combined with the heavy components at the bottom of the decoking tower C1 to go to the downstream device.

[0013] Among them, the composition of ethylene tar is distinguished according to the Engler distillation range, and its initial distillation point temperature to 70% distillation temperature range is 183 ~ 315 ℃.

[0014] The decoking tower C1 is a plate-type and packed mixed tower, the ethylene tar feed temperature is 200-250°C, the tower top operating pressure is 0.005-0.02MPa(A), the tower top operating temperature is 130-200°C, the tower bottom operating pressure is 0.008-0.028MPa(A), and the tower bottom operating temperature is 250-310°C. The heating medium of the forced circulation reboiler E1 is heat transfer oil.

[0015] The light-removal tower C2 is a packed tower, with a top operating pressure of 0.001-0.010 MPa (A), a top operating temperature of 80-150° C., a bottom operating pressure of 0.009-0.018 MPa (A), and a bottom operating temperature of 100-200° C. The heating medium of the forced circulation reboiler E2 is heat transfer oil.

[0016] The industrial naphthalene tower C3 is a plate tower or a packed tower, the top operating pressure is 0.005MPa(A) to 0.02MPa(A), and the operating temperature is 100°C to 150°C.

[0017] The condensate from the top of the industrial naphthalene tower (C3) is mainly industrial naphthalene, and is characterized in that the industrial naphthalene obtained in step (2) has a purity of more than 95%, a crystallization point of more than 77.5° C., and an ash content of ≤0.02%.

[0018] The methylnaphthalene tower C4 is a plate tower or a packed tower, the top operating pressure is 0.001MPa(A) to 0.020MPa(A), and the operating temperature is 130°C to 200°C.

[0019] The condensate from the top of the C4 tower of the methylnaphthalene tower is mainly medium-quality tar, characterized in that the composition of the medium-quality tar obtained in step (3) is differentiated according to the Engler distillation range, and the temperature range from the initial distillation point to the final distillation point is 200-250°C.

[0020] The mixed methylnaphthalene product extracted from the side line of the C4 tower of the methylnaphthalene tower has the following indicators: methylnaphthalene content (wt) ≥ 80%, naphthalene content ≤ 10%, and moisture content ≤ 1%.

[0021] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0022] (1) The industrial naphthalene produced by this process has a high purity, which can reach more than 95%.

[0023] (2) The mixed methylnaphthalene produced by this process has a high purity, which can reach more than 80%.

[0024] (3) The processing technology is simple and efficient, the products are rich and comprehensive, and the investment cost is low;

[0025] (4) High economic and social benefits. The present invention utilizes cheap ethylene tar to produce high value-added industrial naphthalene, mixed methyl naphthalene and medium-quality tar products, with significant economic benefits. At the same time, it reduces the use of ethylene tar as fuel oil, which is green and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments, and the above and / or other advantages of the present invention will become more clear.

[0027] Figure 1 It is a schematic diagram of a method and device for producing aromatic compounds, wherein C1-decoking tower, C2-light removal tower, C3-industrial naphthalene tower, C4-methylnaphthalene tower, E1-forced circulation reboiler 1, E2-forced circulation reboiler 2, E3-condenser 1, E4-forced circulation reboiler 3, E5-condenser 2, E6-forced circulation reboiler 3, E7-condenser 3, V1-buffer tank 1, V2-buffer tank 2, V3-buffer tank 3 , P1-Reboiling circulation pump 1, P2-Decoking tower production pump, P3-Reboiling circulation pump 2, P4-Vacuum pump 1, P5-Light phase production pump of decoking tower, P6-Light phase production pump of decoking tower kettle, P7-Reboiling circulation pump 3, P8-Vacuum pump 2, P9-Industrial naphthalene tower reflux pump, P10-Industrial naphthalene tower kettle pump, P11-Reboiling circulation pump 4, P12-Vacuum pump 3, P13-Methyl naphthalene tower reflux pump, P14-Methyl naphthalene tower kettle pump. DETAILED DESCRIPTION

[0028] In order to more clearly illustrate the technical solution of the present invention, specific embodiments of the relevant technical solution are given below in combination with the contents of the specification. It should be understood that the following embodiments do not constitute a limitation on the protection scope of the present invention, and any technical solution formed by the evolution and improvement of the present invention without creative labor by any technician in the relevant technical field belongs to the protection scope of the present invention.

[0029] The petroleum resin production method and device using the above device are described in detail below through specific embodiments.

[0030] like Figure 1As shown, the present application proposes an aromatic compound production device, comprising a decoking tower C1, a light-removing tower C2, an industrial naphthalene tower C3 and a methylnaphthalene tower C4 connected in sequence, wherein the bottoms of the decoking tower C1, the light-removing tower C2, the industrial naphthalene tower C3 and the methylnaphthalene tower C4 are respectively provided with a forced circulation reboiler, and the tops of the light-removing tower C2, the industrial naphthalene tower C3 and the methylnaphthalene tower C4 are respectively provided with a condenser and a buffer tank connected in sequence, and the top of each buffer tank is respectively connected to a vacuum pump, and a part of the bottom component is refluxed to the original tower top, and a part is used as a production outlet; wherein the top of the decoking tower C1 is connected to the inlet of the light-removing tower C2, and the bottom of the light-removing tower C2 is provided with a reflux pipeline, a part of which refluxes to the top of the decoking tower C1 and the other part is connected to the inlet of the industrial naphthalene tower C3, and the bottom discharge port of the industrial naphthalene tower C3 is connected to the inlet of the methylnaphthalene tower C4.

[0031] The decoking tower C1 is a plate-type and packed mixed tower, the light-removing tower C2 is a packed tower, the industrial naphthalene tower C3 is a plate-type tower or a packed tower, and the methylnaphthalene tower C4 is a plate-type tower or a packed tower.

[0032] The heating medium of the forced circulation reboiler is heat transfer oil.

[0033] The following embodiments are all implemented based on this device.

[0034] Example 1

[0035] The ethylene tar raw material in this embodiment comes from an ethylene plant. The composition of ethylene tar is as follows:

[0036] Table 1 Properties of Raw Material 1 (Ethylene Tar)

[0037]

[0038] Ethylene tar is used as raw material. The raw material is heated to 200℃ by a heat exchanger and enters the decoking tower (C1). A forced circulation reboiler 1 (E1) is set at the bottom of the decoking tower. The light component temperature at the top of the decoking tower (C1) is 152℃ and the pressure is 13KPa (A). It enters the decoking tower (C2). The heavy component at the bottom of the decoking tower (C1) goes to the downstream device. The decoking tower (C2) is operated under reduced pressure, and a forced circulation reboiler 2E2 is set at the bottom of the tower. The top gas temperature is 97℃ and the pressure is 5KPa (A). After being cooled by the decoking tower condenser E3, it enters the buffer tank 1V1. The heavy component at the bottom of the decoking tower C2 has a temperature of 152℃ and a pressure of 13KPa (A). Part of it is used as the reflux of the decoking tower C1 through the decoking tower bottom extraction pump P6, and part of it is sent to the industrial naphthalene tower. The top of the buffer tank 1V1 is connected to the vacuum pump 1P4 to extract the non-condensable gas, and the pressure is controlled to be 3KPa (A). The oil phase in the buffer tank V1 is pumped out to the downstream device through the light phase extraction pump P5 of the light phase removal tower.

[0039] The industrial naphthalene tower C3 is operated under reduced pressure, and a forced circulation reboiler 3E4 is installed in the tower bottom. The temperature at the top of the industrial naphthalene tower is 135°C and the pressure is 10KPa (A). The top gas enters the buffer tank 2V2 after being cooled by the condenser 2E5. The light components at the top of the tower are partially refluxed through the industrial naphthalene tower reflux pump P9, and part of them are sent out as industrial naphthalene products. The bottom temperature of the industrial naphthalene tower C3 is 182°C and the pressure is 20KPa (A). The heavy components at the bottom of the tower are sent to the methyl naphthalene tower C4 through the industrial naphthalene tower kettle pump P10. The top of the buffer tank 2V2 is connected to the vacuum pump 2P8 to extract the non-condensable gas and control the pressure of the buffer tank 2V2 to 7KPa (A).

[0040] The methylnaphthalene tower C4 is operated under reduced pressure, and a forced circulation reboiler 4E6 is installed in the tower bottom. The tower top temperature is 156℃, and the pressure is 15KPa(A). The light components at the top of the tower are cooled by the methylnaphthalene tower top condenser E7 and then enter the buffer tank 3V3. The light components at the top of the tower are partially refluxed through the methylnaphthalene tower reflux pump P13, and partially sent out as medium-quality tar products. The methylnaphthalene product is extracted from the methylnaphthalene tower C4 side line. The tower bottom temperature of the methylnaphthalene tower C4 is 212℃, and the pressure is 25KPa(A). The heavy components at the bottom of the tower are pumped out by the methylnaphthalene tower kettle pump P14 and combined with the heavy components at the bottom of the decoking tower C1 to the downstream device.

[0041] The quality of the obtained product is: industrial naphthalene purity reaches 95.6%, crystallization point 77.9℃, ash content ≤0.02%; methylnaphthalene content (wt) 81%, naphthalene content 9%, moisture content ≤1%; the properties of the obtained medium-quality tar product are as follows:

[0042] Table 2

[0043]

[0044] Example 2

[0045] The apparatus and operation steps of this embodiment are the same as those of embodiment 1, except that the composition of the raw material ethylene tar is changed, as shown in the following table:

[0046] Table 3 Properties of Raw Material 2 (Ethylene Tar)

[0047]

[0048] The quality of the obtained product is: industrial naphthalene purity reaches 96.5%, crystallization point 78.2℃, ash content ≤0.01%; methylnaphthalene content (wt) 83%, naphthalene content 7%, moisture content ≤1%; the properties of the obtained medium-quality tar product are as follows:

[0049] Table 4

[0050]

[0051] The invention utilizes cheap ethylene tar to produce high-value-added industrial naphthalene, mixed methyl naphthalene and medium-quality tar products, with remarkable economic benefits. Meanwhile, the usage of ethylene tar as fuel oil is reduced, which is environmentally friendly. High-value-added aromatic compound series products are separated by connecting multiple vacuum distillation towers in series, so that the purity of industrial naphthalene reaches more than 95%, and the purity of mixed methyl naphthalene reaches more than 80%, thus forming an efficient technical method for preparing aromatic compound series products from ethylene tar.

Claims

1. A method for producing an aromatic compound, characterized in that: The steps include: (1) Ethylene tar is used as raw material. After being heated by a preheater, the raw material enters a decoking tower (C1). A forced circulation reboiler 1 (E1) is provided at the bottom of the decoking tower. After being processed in the decoking tower (C1), the light components at the top of the tower enter a light-removing tower (C2), and the components at the bottom of the tower are sent to downstream devices. The degassing tower (C2) is operated under reduced pressure, and a forced circulation reboiler 2 (E2) is installed in the bottom of the tower. The top gas is cooled by the degassing tower condenser (E3) and then enters the buffer tank 1 (V1). The top of the buffer tank 1 (V1) is connected to the vacuum pump 1 (P4) to extract the non-condensable gas. The oil phase in the buffer tank 1 (V1) is pumped out by the light phase extraction pump (P5) of the degassing tower, part of which goes to the downstream device, and part of which is refluxed to the degassing tower (C2); the heavy components at the bottom of the degassing tower (C2) are partly refluxed to the decoking tower (C1) through the degassing tower bottom extraction pump (P6), and part of which is sent to the industrial naphthalene tower (C3); (2) The industrial naphthalene tower (C3) is operated under reduced pressure. A forced circulation reboiler 3 (E4) is installed in the bottom of the tower. The top gas is cooled by the condenser 2 (E5) and then enters the buffer tank 2 (V2). The top of the buffer tank 2 (V2) is connected to the vacuum pump 2 (P8) to extract the non-condensable gas. The components in the buffer tank 2 (V2) are refluxed by the reflux pump (P9), and the rest are sent out as industrial naphthalene products. The heavy components at the bottom of the industrial naphthalene tower (C3) are sent to the methyl naphthalene tower (C4) by the industrial naphthalene tower bottom pump (P10). (3) The methylnaphthalene tower (C4) is operated under reduced pressure, and a forced circulation reboiler 4 (E6) is installed in the bottom of the tower. The light components at the top of the tower are cooled by the methylnaphthalene tower top condenser (E7) and then enter the buffer tank 3 (V3). The top of the buffer tank 3 (V3) is connected to the vacuum pump 3 (P12) to extract the non-condensable gas. The components in the buffer tank 3 (V3) are refluxed through the reflux pump (P13), and the rest are sent out as medium-quality tar products. The methylnaphthalene product is extracted from the side line of the methylnaphthalene tower (C4). The heavy components at the bottom of the methylnaphthalene tower (C4) are pumped out through the methylnaphthalene tower kettle pump (P14) and combined with the heavy components at the bottom of the decoking tower (C1) to go to the downstream device.

2. The method according to claim 1, characterized in that The ethylene tar in step (1) is a high-temperature condensation product of raw materials and products of ethylene cracking raw materials in the process of steam cracking to produce ethylene, wherein the components of ethylene tar are differentiated according to the Engler distillation range, and the range of the initial distillation point temperature to the 70% distillation temperature is 183-315°C.

3. The method according to claim 1, characterized in that The decoking tower (C1) of step (1) is a plate-type and packed mixed tower, the ethylene tar feed temperature is 200-250°C, the top operating absolute pressure is 0.005-0.02MPa, the top operating temperature is 130-200°C, the bottom operating absolute pressure is 0.008-0.028MPa, and the bottom operating temperature is 250-310°C; the heating medium of the forced circulation reboiler 1 (E1) is heat transfer oil.

4. The method according to claim 1, characterized in that: The light removal tower (C2) in step (1) is a packed tower, the top operating absolute pressure is 0.001-0.010 MPa, the top operating temperature is 80-150°C, the bottom operating absolute pressure is 0.009-0.018 MPa, the bottom operating temperature is 100-200°C, and the heating medium of the forced circulation reboiler 2 (E2) is heat transfer oil.

5. The method according to claim 1, characterized in that The industrial naphthalene tower (C3) in step (2) is a plate tower or a packed tower, the absolute pressure of the top operation is 0.005MPa~0.02MPa, and the operating temperature is 100 o C~150 o C.

6. The method according to claim 1, characterized in that The methylnaphthalene tower (C4) in step (3) is a plate tower or a packed tower, and the absolute pressure at the top of the tower is 0.001MPa(A)~0.020MPa, and the operating temperature is 130 o C~200 o C.

7. A production device for aromatic compounds, characterized in that: The invention comprises a decoking tower (C1), a lightness removal tower (C2), an industrial naphthalene tower (C3) and a methyl naphthalene tower (C4) which are connected in sequence, wherein the bottoms of the decoking tower (C1), the lightness removal tower (C2), the industrial naphthalene tower (C3) and the methyl naphthalene tower (C4) are respectively provided with a forced circulation reboiler, and the tops of the lightness removal tower (C2), the industrial naphthalene tower (C3) and the methyl naphthalene tower (C4) are respectively provided with a condenser and a buffer tank which are connected in sequence, and the top of each buffer tank is respectively connected to a vacuum pump, and a part of the bottom components is refluxed to the original tower top, and a part is used as a production outlet; wherein the top of the decoking tower (C1) is connected to the inlet of the lightness removal tower (C2), and the bottom of the lightness removal tower (C2) is provided with a reflux pipeline, a part of which is refluxed to the top of the decoking tower (C1), and the other part is connected to the inlet of the industrial naphthalene tower (C3), and the bottom discharge port of the industrial naphthalene tower (C3) is connected to the inlet of the methyl naphthalene tower (C4).

8. The production device according to claim 7, characterized in that: The decoking tower (C1) is a mixed tower of plate and packing, the lightness removal tower (C2) is a packing tower, the industrial naphthalene tower (C3) is a plate tower or a packing tower, and the methylnaphthalene tower (C4) is a plate tower or a packing tower.

9. The production device according to claim 7, characterized in that: The heating medium of the forced circulation reboiler is heat transfer oil.

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