A coking crude benzene hydrogenation separation system and process coupled with a styrene production unit

Abstract

The present invention relates to a coking crude benzene hydrogenation separation system and process coupled with a styrene production unit. The present invention utilizes the characteristic that the catalyst in the alkylation stage of catalytic dehydrogenation of ethylbenzene to produce styrene only reacts with aromatic benzene, while non-aromatic hydrocarbons hardly participate in the reaction. By coupling the crude benzene hydrogenation refining unit with the styrene production unit, the cumbersome extraction and distillation system used in the crude benzene hydrogenation refining process is eliminated, achieving the purpose of separating non-aromatic hydrocarbons in the styrene production unit. This reduces the energy consumption of the coking crude benzene separation system and the investment cost of the unit construction.

Description

Technical Field

[0001] The present invention relates to the field of coal chemical technology, and more particularly to the field of hydrogenation of crude coking benzene, a by-product of coal coking to produce coal gas, coke, and tar. Specifically, the present invention relates to a crude coking benzene hydrogenation separation system and process coupled to a styrene production unit. Background Art

[0002] Coking crude benzene is a byproduct of the coal coking process to produce coal gas, coke, and tar. It is recovered from coke oven gas by washing with oil. The main components of coking crude benzene are aromatic hydrocarbons such as benzene, toluene, and xylene, accounting for over 85%, while the remaining 10% consists of non-aromatic hydrocarbons, unsaturated hydrocarbons, and compounds containing sulfur, nitrogen, and oxygen. Crude benzene undergoes refining to produce products such as hydrogenated benzene, hydrogenated toluene, and xylene. Currently, the main crude benzene refining processes are acid washing and hydrorefining. The crude benzene hydrorefining process involves hydrogenating oxygen-, nitrogen-, and sulfur-containing substances in crude benzene under certain temperature and pressure conditions in the presence of a catalyst to produce water, ammonia, and hydrogen sulfide, which can be separated. Unsaturated hydrocarbons are hydrogenated to saturate, while the main aromatic components such as benzene and toluene do not undergo hydrogenation and are retained, ultimately becoming qualified hydrogenated oil.

[0003] The traditional coking crude benzene hydrogenation oil separation process is a 6-tower separation process, which mainly includes a stabilization tower, a pre-separation tower, an extractive distillation tower, a stripping tower, a benzene / toluene separation tower and a xylene tower. Figure 1 As shown, the hydrogenated oil is separated from aromatics and non-aromatics in a pre-separation tower and fed to an extraction tower. With an extractant at a volume 7-8 times the feedstock, the non-aromatics are separated from the aromatics and sold as products. The remaining aromatics, consisting of benzene and toluene, enter the benzene / toluene tower, where they are separated to produce high-purity benzene and toluene products, respectively. The pre-separation tower bottoms primarily contain a C8+ fraction containing mixed xylenes and high-boiling-point substances. After entering the xylene tower, a small amount of C8 solvent oil is separated overhead, and mixed xylenes are obtained as a side product. The bottoms contain C9+ solvent oil. In this process, since toluene and xylene have similar uses, separating them from each other consumes a significant amount of energy, resulting in waste. Furthermore, since non-aromatics account for only approximately 1% of the aromatics, the amount of extractant required for extractive distillation is 7-8 times the feedstock volume, and the subsequent separation of the extractant consumes significant energy. Therefore, this traditional process is unsuitable for current production and social environments.

[0004] Ethylbenzene catalytic dehydrogenation is one of the methods for producing styrene. The main process flow is as follows: Figure 2As shown, benzene and ethylene undergo an alkylation reaction over a molecular sieve catalyst to produce ethylbenzene, simultaneously generating byproducts polyethylbenzenes and a small amount of non-aromatic hydrocarbons. The products are separated in a benzene recovery tower, where benzene and non-aromatic hydrocarbons are separated at the top of the kettle. Benzene is recovered through a benzene recovery unit, and non-aromatic hydrocarbons are separated through a lightness removal tower to produce non-aromatic hydrocarbon products. The bottom components separated at the bottom of the benzene recovery tower are then separated to produce polyethylbenzenes and ethylbenzene products. The ethylbenzene product enters a dehydrogenation reactor for dehydrogenation. Under the action of a catalyst, ethylbenzene is dehydrogenated at high temperature to produce styrene and hydrogen, with the production of byproducts such as benzene, toluene, C1-C4 alkanes, and large organic compounds. The products are separated in a pre-separation tower at the top of the kettle, where benzene and toluene are sent to a benzene / toluene tower for separation to produce byproducts such as benzene and toluene. The bottom components separated at the bottom of the pre-separation tower are separated in a styrene separation unit to produce styrene and tar products, respectively. The recovered benzene and byproduct benzene products are returned to the feedstock system to continue reacting with ethylene, with toluene, polyethylbenzenes, and tar being sold as products. Summary of the Invention

[0005] Given that styrene is a major downstream industry chain in crude benzene refining, the present invention utilizes the characteristic that the catalyst in the alkylation section of ethylbenzene catalytic dehydrogenation to produce styrene only acts on aromatic benzene and non-aromatic hydrocarbons hardly participate in the reaction. By coupling the crude benzene hydrorefining unit with the styrene production unit, the cumbersome extraction and distillation system in the crude benzene hydrorefining process is eliminated, and the purpose of separating non-aromatic hydrocarbons in the styrene production unit is achieved, thereby reducing the energy consumption of the coking crude benzene separation system and the investment cost of the unit construction.

[0006] Based on this, the first aspect of the present invention proposes a coking crude benzene hydrogenation separation system coupled with a styrene production unit, such as Figure 3 Shown, including:

[0007] Light benzene separation tower 1, having

[0008] The feed inlet is located in the lower middle part of the light benzene separation tower 1 and is used to inject coking crude benzene hydrogenation oil, benzene / toluene fraction from the styrene production unit and aromatic components returned from the subsequent benzene product tower 3;

[0009] The top outlet is used to send out aromatic hydrocarbons below C7, non-aromatic hydrocarbons and inorganic components (such as hydrogen sulfide, ammonia, water vapor, etc.); and

[0010] The tower bottom outlet is located at the bottom of the light benzene separation tower 1 and is used to output aromatic hydrocarbons and non-aromatic hydrocarbon components above C7;

[0011] Tail gas tower 2, with

[0012] A feed inlet is located in the lower middle portion of the tail gas tower 2 and is connected to the top outlet of the light benzene separation tower 1;

[0013] The top outlet is used to send out non-condensable tail gas (including inorganic components and C1-C6 non-aromatic hydrocarbons, etc.); and

[0014] The bottom outlet is located at the bottom of the tail gas tower 2 and is used to output the bottom liquid (whose main component is benzene);

[0015] Benzene product tower 3, having

[0016] A feed inlet is located in the lower middle portion of the benzene product tower 3 and is connected to the bottom outlet of the tail gas tower 2;

[0017] The top outlet is used to produce C4-C7 non-aromatic hydrocarbons;

[0018] The side outlet is used to output the benzene product to the styrene production unit as a raw material for styrene production;

[0019] The bottom outlet is located at the bottom of the benzene product tower 3, and is used to extract the bottom liquid containing aromatic hydrocarbons (mainly benzene) and output it to the feed inlet of the light benzene separation tower 1;

[0020] Solvent oil product tower 4, with

[0021] The feed inlet is located in the middle of the solvent oil product tower 4 and is connected to the outlet of the kettle of the light benzene separation tower;

[0022] The outlet at the top of the tower is used to produce solvent oil products;

[0023] The tower bottom outlet is located at the bottom of the solvent oil product tower 4 and is used to output heavy aromatic solvent oil products above C9.

[0024] The above coking crude benzene hydrogenation separation system and Figure 2 After the styrene production unit shown is coupled, Figure 2 The benzene / toluene fraction separated from the top of the kettle by the intermediate pre-separation tower can be sent to the light benzene separation tower 1 in the above-mentioned coking crude benzene hydrogenation separation system for separation, and the benzene / toluene tower of the styrene unit can be shut down.

[0025] In the coking crude benzene hydrogenation separation system of the present invention, to achieve the aforementioned objectives of each tower, all of the aforementioned towers (including the light benzene separation tower 1, tail gas tower 2, benzene product tower 3, and solvent oil product tower 4) may, as needed, be equipped with one or more of the following equipment: an overhead heat exchanger, a reflux drum, a transfer pump, or a reboiler. Based on the common knowledge of those skilled in the art, detailed descriptions are omitted here. For example, the overheads of the light benzene separation tower and the benzene product tower may be equipped with a steam generator 1 to increase the overhead operating pressure and temperature of the towers and to generate byproduct steam, thereby saving energy and reducing consumption.

[0026] In some embodiments, the coking crude benzene hydrogenation separation system of the present invention further comprises: Figure 4As shown, a steam generator is provided on the pipeline connecting the top outlet of the light benzene separation tower 1 and the feed inlet of the tail gas tower 2.

[0027] In some embodiments, the coking crude benzene hydrogenation separation system of the present invention further includes a processing device for treating the non-condensable tail gas discharged from the top outlet of the tail gas tower 2, which includes:

[0028] A cooling device connected to the top outlet of the tail gas tower 2 is used to cool and liquefy the organic materials in the tail gas; when passing through the cooling device, most of the organic materials in the tail gas will be cooled and liquefied;

[0029] A reflux tank, which receives the liquefied organic material cooled by the cooling device. For example, the liquid material in the reflux tank can be used only as reflux to ensure that benzene is not carried away by the gas phase; and

[0030] The waste gas treatment system receives the non-condensable gases, such as inorganic components (hydrogen sulfide, ammonia, water vapor, etc.) and organic non-condensable gases, after being cooled by the cooling device, and treats them. For example, the inorganic components such as hydrogen sulfide, ammonia, water vapor, etc. can be rendered harmless, and the organic non-condensable gases, such as methane, can be used as fuel.

[0031] In some embodiments, in the benzene product 3, the C4-C7 non-aromatic hydrocarbons extracted from the top outlet also contain benzene, that is, the extracted gas is a mixture of C4-C7 non-aromatic hydrocarbons and benzene, the side outlet is used to output the benzene product or is closed, and the bottom outlet is used to extract the bottom liquid of the aromatic component whose main component is benzene and output it to the feed port of the light benzene separation tower 1. Therefore, the coking crude benzene hydrogenation separation system of the present invention can also include, such as Figure 5 As shown, the processing equipment for processing the mixed gas of C4-C7 non-aromatic hydrocarbons and benzene extracted from the top outlet of the benzene product tower 3 includes:

[0032] Steam generator II, which is connected to the top outlet of benzene product tower 3 and is used to heat exchange and cool the mixed gas of C4-C7 non-aromatic hydrocarbons and benzene produced from the top outlet of benzene product tower 3;

[0033] A reflux tank connected to the steam generator II and having a bottom outlet, wherein the bottom outlet and the side outlet of the benzene product column 3 are connected to the styrene production unit for outputting the benzene product to the styrene production unit;

[0034] A cooler is provided above the reflux tank and is connected back to the reflux tank. The cooler condenses the benzene in the mixed gas of C4-C7 non-aromatic hydrocarbons and benzene extracted from the top outlet of the benzene product tower 3 to separate liquid benzene and gaseous C4-C7 non-aromatic hydrocarbons, and refluxes the liquid benzene to the reflux tank.

[0035] In some embodiments, the processing equipment for processing the mixed gas of C4-C7 non-aromatic hydrocarbons and benzene extracted from the top outlet of the benzene product tower 3 also includes a secondary cooler, which is arranged above the cooler to receive the gaseous C4-C7 non-aromatic hydrocarbons discharged from the cooler for cooling and liquefying the gaseous C4-C7 non-aromatic hydrocarbons.

[0036] In some embodiments, the coking crude benzene hydrogenation separation system of the present invention further includes an intermediate tank I, which is arranged upstream of the light benzene separation tower 1 and connected to the feed port of the light benzene separation tower 1, and is used to store and / or mix hydrogenated oil, benzene / toluene fractions from the styrene production unit and aromatic components returned from the subsequent benzene product tower 3.

[0037] In some embodiments, the coking crude benzene hydrogenation separation system of the present invention further includes an intermediate tank II, which is connected to the side outlet of the benzene product tower 3 and the bottom outlet of the reflux drum to receive the benzene product from the side outlet of the benzene product tower 3 and the bottom outlet of the reflux drum, and is connected to the styrene production unit to output the benzene product to the styrene production unit.

[0038] In the above-mentioned coking crude benzene hydrogenation separation system, among the components separated by the light benzene separation tower 1, the aromatic components below C7 are mainly benzene and toluene; the non-aromatic hydrocarbons below C7 include, for example, methane, ethane, propane, butane, pentane, hexane, heptane, cyclohexane, methylcyclohexane, etc.; the inorganic substances include, for example, hydrogen sulfide, ammonia, water vapor, etc.; the aromatic components above C7 include toluene, mixed xylenes and aromatic hydrocarbons and non-aromatic hydrocarbons above C9, such as trimethylbenzene, indane, naphthalene, tetralin and other condensed-ring aromatic hydrocarbons, etc.

[0039] In the above-mentioned coking crude benzene hydrogenation separation system, the non-condensable tail gas separated from the top outlet of the tail gas tower 2 includes: inorganic substances, such as hydrogen sulfide, ammonia, water vapor; C1-C6 non-aromatic hydrocarbons, such as methane, ethane, propane, butane, pentane, hexane, etc.

[0040] In the above-mentioned coking crude benzene hydrogenation separation system, the bottom liquid output at the bottom outlet of the tail gas tower 2, the main component of which is benzene (for example, more than 90 wt%, further for example, more than 93 wt%), usually also contains a small amount of toluene (for example, 1 wt% to 10 wt%, further for example, 3 wt% to 4 wt%) and a small amount of C4-C8 non-aromatic hydrocarbons (for example, 1 wt% to 5 wt%, further for example, 2 wt% to 3 wt%).

[0041] In the above-mentioned coking crude benzene hydrogenation separation system, the C4-C7 non-aromatic hydrocarbons extracted from the benzene product tower 3 usually contain a small amount of benzene (e.g., 5 wt % to 20 wt %, further e.g., 10 wt % to 13 wt %).

[0042] In the above-mentioned coking crude benzene hydrogenation separation system, the benzene product output to the styrene production unit at the side outlet of the benzene product column 3 and / or the bottom outlet of the reflux drum usually contains a small amount of C4-C7 non-aromatic hydrocarbons (for example, 0.1-1.0 wt %, further for example, 0.4-0.5 wt %), and the C4-C7 non-aromatic hydrocarbons contained include cyclohexane and methylcyclohexane. The C4-C7 non-aromatic hydrocarbons can be obtained from Figure 2 The tail gas tower discharge of the styrene unit is shown.

[0043] In the above-mentioned coking crude benzene hydrogenation separation system, the bottom liquid extracted at the bottom outlet of the benzene product tower 3, whose main component is benzene and aromatic components, also contains a small amount of toluene (e.g., 5 wt% to 20 wt%, further e.g., 10 to 15 wt%).

[0044] In the above-mentioned coking crude benzene hydrogenation separation system, the solvent oil product extracted at the top outlet of the solvent oil product tower 4 is a mixture of toluene and xylene, which may contain a small amount of C6-C8 non-aromatic hydrocarbons (for example, 0.5 wt% to 5.0 wt%, further for example, 1.0 wt% to 2.0 wt%).

[0045] The second aspect of the present invention provides a coking crude benzene hydrogenation separation process coupled with a styrene production process, which is one of the following methods:

[0046] Method 1: Using the above Figure 3 Or the coking crude benzene hydrogenation separation system shown in 4, comprising the following steps:

[0047] S1. The hydrogenated oil obtained after hydrogenation of the coking crude benzene is mixed with the benzene / toluene material returned from the styrene production process and / or the aromatic components returned from the subsequent benzene product column, and then fed into the light benzene separation column. After treatment, aromatic hydrocarbons below C7, non-aromatic hydrocarbons, and inorganic components are extracted from the top outlet of the light benzene separation column and enter the tail gas column; aromatic hydrocarbons above C7 and non-aromatic hydrocarbons are transported from the bottom outlet of the light benzene separation column to the solvent oil product column for treatment;

[0048] S2. The aromatic hydrocarbons, non-aromatic hydrocarbons, and inorganic components below C7 extracted from the top outlet of the light benzene separation tower are processed in the tail gas tower. The non-condensable tail gas (including inorganics and C1-C6 non-aromatic hydrocarbons) is separated from the top outlet of the tail gas tower. The bottom liquid is transported from the bottom outlet of the tail gas tower to the benzene product tower for processing;

[0049] S3. The tail gas column bottoms liquid is processed in the benzene product column, and C4-C7 non-aromatic hydrocarbons are produced from the top outlet of the benzene product column; benzene product is produced from the side outlet of the benzene product column and transported to the styrene production unit; the bottoms liquid containing aromatic components is produced from the bottom outlet of the benzene product column, and the bottoms liquid is output to the light benzene separation column through the bottom outlet of the benzene product column to continuously recover the benzene product;

[0050] S4. After the aromatic and non-aromatic components above C7 output from the light benzene separation tower are processed in the solvent oil product tower, a solvent oil product is produced from the top outlet of the solvent oil product tower; and a heavy aromatic solvent oil product above C9 is output from the bottom outlet of the solvent oil product tower.

[0051] Method 2: Using the above Figure 5 The coking crude benzene hydrogenation separation system shown includes the following steps:

[0052] S1 '. The hydrogenated oil obtained after the hydrogenation of the coking crude benzene is qualified, and the benzene / toluene material returned from the styrene production process and / or the aromatic components returned from the subsequent benzene product tower are mixed and input into the light benzene separation tower. After treatment, aromatic hydrocarbons below C7, non-aromatic hydrocarbons and inorganic components are extracted from the top outlet of the light benzene separation tower and enter the tail gas tower; the aromatic and non-aromatic components above C7 are transported to the solvent oil product tower at the kettle outlet of the light benzene separation tower for treatment;

[0053] S2 'from the light benzene separation tower top outlet extracted C7 below aromatics, non-aromatics and inorganic components, after the tail gas tower treatment, from the tail gas tower top outlet separated non-condensable tail gas (including inorganics and C1-C6 non-aromatics, etc.), the bottom liquid through the tail gas tower bottom outlet transported to the benzene product tower treatment;

[0054] S3'. The tail gas tower bottom liquid is processed by the benzene product tower, and a mixture of C4-C7 non-aromatic hydrocarbons and benzene is extracted from the top outlet of the benzene product tower; the mixed gas is sequentially sent to the cooler through the steam generator II and the reflux tank for condensation to separate liquid benzene and gaseous C4-C7 non-aromatic hydrocarbons. The liquid benzene is refluxed to the reflux tank and the benzene product is output to the styrene production unit through the bottom outlet of the reflux tank; at the same time, the benzene product tower side outlet is opened or closed, and when opened, the benzene product is output to the styrene production unit; the benzene product tower bottom outlet extracts the bottom liquid of the aromatic component, and the bottom liquid is output to the light benzene separation tower through the benzene product tower bottom outlet to continuously recover the benzene product;

[0055] S4'. The aromatic and non-aromatic components above C7 output from the light benzene separation tower are processed by the solvent oil product tower, and the solvent oil product is extracted from the top outlet of the solvent oil product tower; the heavy aromatic solvent oil product above C9 is output from the bottom outlet of the solvent oil product tower.

[0056] In the above-mentioned coking crude benzene hydrogenation separation process, in step S1 or S1', among the components separated by the light benzene separation tower, the aromatic hydrocarbon components below C7 are mainly benzene and toluene; the non-aromatic hydrocarbons below C7 include, for example, methane, ethane, propane, butane, pentane, hexane, heptane, cyclohexane, methylcyclohexane, etc.; the inorganic substances include, for example, hydrogen sulfide, ammonia, water vapor, etc.; the aromatic hydrocarbon components above C7 include toluene, mixed xylenes and aromatic hydrocarbons and non-aromatic hydrocarbons above C9, such as trimethylbenzene, naphthalene, tetralin and other condensed-ring aromatic hydrocarbons.

[0057] According to the above coking crude benzene hydrogenation separation process, in step S1 or S1', the components extracted from the top of the light benzene separation tower are controlled to contain less than 5 wt% toluene, for example, 0.1 wt%-5 wt%, to ensure that benzene is evaporated as much as possible.

[0058] In the above-mentioned coking crude benzene hydrogenation separation process, in step S2 or S2', the non-condensable tail gas separated from the top outlet of the tail gas tower includes: inorganic substances, such as hydrogen sulfide, ammonia, water vapor, C1-C6 non-aromatic hydrocarbons, such as methane, ethane, propane, butane, pentane, hexane, etc.

[0059] In the above-mentioned coking crude benzene hydrogenation separation process, in step S2 or S2', the bottom liquid, whose main component is benzene (for example, more than 90 wt%, further for example, more than 93 wt%), which is transported to the benzene product tower through the bottom outlet of the tail gas tower, usually also contains a small amount of toluene (for example, 1 wt% to 10 wt%, further for example, 3 wt% to 4 wt%) and a small amount of C4-C8 non-aromatic hydrocarbons (for example, 1 wt% to 5 wt%, further for example, 2 wt% to 3 wt%).

[0060] In the above-mentioned coking crude benzene hydrogenation separation process, in step S3 or step S3', the C4-C7 non-aromatic hydrocarbons extracted from the benzene product tower usually contain a small amount of benzene (for example, 5 wt% to 20 wt%, and further for example, 10 wt% to 13 wt%). The C4-C7 non-aromatic hydrocarbons include pentane, hexane, and heptane, with pentane being the main component. Therefore, they are sometimes also called pentane products (wherein the aforementioned alkanes include various forms of isomers, for example, pentane includes isomers such as n-pentane, isopentane, and cyclopentane). The product extracted from the top outlet of the benzene product tower can be used for downstream refining of cyclopentane.

[0061] In the above-mentioned coking crude benzene hydrogenation separation process, in step S3 or step S3', the benzene product output from the benzene product tower side outlet and / or the reflux drum bottom outlet to the styrene production unit usually contains a small amount of C4-C7 non-aromatic hydrocarbons (e.g., 0.1-1.0 wt %, further e.g., 0.4-0.5 wt %), and the C4-C7 non-aromatic hydrocarbons contained include cyclohexane and methylcyclohexane. The C4-C7 non-aromatic hydrocarbons can be obtained from Figure 2 The tail gas tower discharge of the styrene unit is shown.

[0062] In the above-mentioned coking crude benzene hydrogenation separation process, in step S3 or step S3', the bottom liquid of the aromatic hydrocarbon component extracted from the bottom outlet of the tower is mainly benzene and also contains a small amount of toluene. The toluene content in the bottom liquid of the benzene product tower is set to be less than 20% (for example, less than 15 wt %, less than 10 wt %, or for example, the toluene content is 5 wt % to 20 wt %, and another example is 10 to 15 wt %) to ensure that toluene does not enter the benzene product and avoid toluene from having an adverse effect on styrene production.

[0063] In the above-mentioned coking crude benzene hydrogenation separation process, in step S3', the gaseous C4-C7 non-aromatic hydrocarbons can be further cooled and liquefied in a secondary cooler.

[0064] In the above coking crude benzene hydrogenation separation process, in step S4 or S4', the solvent oil product is a mixture of toluene and xylene, which may contain a small amount of C6-C8 non-aromatic hydrocarbons (e.g., 0.5 wt% to 5.0 wt%, further e.g., 1.0 wt% to 2.0 wt%).

[0065] In a specific embodiment, in step S1 or S1',

[0066] When a steam generator is not provided on the pipeline connecting the top outlet of the light benzene separation tower and the feed inlet of the tail gas tower, the top pressure of the light benzene separation tower is 0.05-0.08 MPaG, and the temperature is 98-110° C.; the bottom pressure is 0.100-0.120 MPaG, and the temperature is 145-155° C. Preferably, the top pressure of the light benzene separation tower is 0.064 MPaG, and the temperature is 108° C.; the bottom pressure is 0.108 MPaG, and the temperature is 147° C.

[0067] When a steam generator is provided on the pipeline connecting the top outlet of the light benzene separation tower and the feed inlet of the tail gas tower, the top pressure of the light benzene separation tower is 0.6-0.9 MPaG, and the temperature is 160-170° C.; the bottom pressure is 0.65-0.95 MPaG, and the temperature is 180-190° C. Preferably, the top pressure of the light benzene separation tower is 0.7-0.8 MPaG, and the temperature is 165-170° C.; the bottom pressure is 0.744-0.844 MPaG, and the temperature is 185-188° C.

[0068] In a specific embodiment, in step S2 or S2', the operating pressure at the top of the tail gas tower is 0.400-0.500 MPaG, and the temperature is 105-115°C; the operating pressure at the bottom of the tower is 0.450-0.500 MPaG, and the temperature is 150-165°C. Preferably, the operating pressure at the top of the tail gas tower is 0.470 MPaG, and the temperature is 110°C; the operating pressure at the bottom of the tower is 0.490 MPaG, and the temperature is 156°C.

[0069] In a specific embodiment, in step S3, the top operating pressure of the benzene product column is 0.05-0.10 MPaG, and the temperature is 70-90°C; the side cutting operating pressure is 0.055-0.06 MPaG, and the temperature is 80-90°C; the bottom operating pressure is 0.08-0.10 MPaG, and the temperature is 130-150°C. Preferably, the top operating pressure of the benzene product column is 0.064 MPaG, and the temperature is 71°C; the side cutting operating pressure is 0.060 MPaG, and the temperature is 83°C; and the bottom operating pressure is 0.080 MPaG, and the temperature is 130°C.

[0070] In a specific embodiment, in step S3',

[0071] When the benzene product tower side outlet is closed, the operating pressure at the top of the benzene product tower is 0.85-1.20 MPaG, and the temperature is 110-185°C; the operating pressure at the bottom of the tower is 1.00-1.40 MPaG, and the temperature is 170-255°C. Preferably, the operating pressure at the top of the benzene product tower is 1.1-1.2 MPaG, and the temperature is 170-173°C; the operating pressure at the bottom of the tower is 1.25-1.30 MPaG, and the temperature is 245-255°C.

[0072] When the side outlet of the benzene product column is open, the operating pressure at the top of the benzene product column is 0.85-1.20 MPaG, and the temperature is 110-185°C; the operating pressure of the side cut is 1.00-1.30 MPaG, and the temperature is 120-188°C; the operating pressure of the bottom of the column is 1.00-1.40 MPaG, and the temperature is 170-255°C. Preferably, the operating pressure at the top of the benzene product column is 1.1-1.2 MPaG, and the temperature is 170-173°C; the operating pressure of the side cut is 1.12-1.22 MPaG, and the temperature is 181-185°C; and the operating pressure of the bottom of the column is 1.25-1.30 MPaG, and the temperature is 245-255°C.

[0073] In a specific embodiment, in step S4 or S4', the top operating pressure of the solvent oil product column is 0.06-0.10 MPaG and the temperature is 120-130°C; the bottom operating pressure is 0.07-0.12 MPaG and the temperature is 220-253°C. Preferably, the top operating pressure of the solvent oil product column is 0.064 MPaG and the temperature is 127°C; the bottom operating pressure is 0.078 MPaG and the temperature is 224°C.

[0074] Beneficial effects

[0075] In this technical solution, the C1-C6 non-aromatic hydrocarbons in the hydrogenated oil are extracted with tail gas and used as fuel. The C6-C8 non-aromatic hydrocarbons are added to the aromatic solvent oil product, which has no stringent purity requirements, along with toluene and mixed xylenes. The C4-C7 non-aromatic hydrocarbons, particularly the C6-C7 non-aromatic hydrocarbons, are added to the benzene product and fed into the styrene production unit. Compared with traditional coking crude benzene hydrogenation separation processes, this method eliminates the need for extraction towers and extractant separation towers, avoids the use of extractants, and significantly reduces energy consumption.

[0076] Theoretically, the higher the purity of the raw materials, the higher the efficiency of the device. However, considering the maximization of the benefits of coupling the crude benzene hydrogenation unit with the styrene unit, it is beneficial to appropriately reduce the purity for the whole. First, the non-aromatic hydrocarbons in the raw benzene have no effect on the alkylation of benzene and ethylene. Secondly, non-aromatic hydrocarbons are also produced in the styrene production process. The two can be considered comprehensively. After the implementation of the scheme of the present invention, the operating conditions are simply changed to transfer the C4-C7 non-aromatic hydrocarbons in the crude benzene hydrogenation process to the styrene production process. The non-aromatic hydrocarbons generated by the alkylation reaction with styrene are uniformly extracted from the styrene light tower. The extraction volume remains unchanged but the benzene content can be significantly reduced. The extracted non-aromatic hydrocarbon products are mainly benzene and pentane, which can be sold directly as products.

[0077] At the same time, while the non-aromatic hydrocarbon content of the styrene production unit's feedstock increases, leading to a certain degree of increased energy consumption, the benzene / toluene mixture separated by the separation tower in the styrene production unit can be directly transferred to the coking crude benzene hydrogenation separation system for subsequent separation along with the hydrogenated oil. This also reduces the construction and operating costs of the benzene / toluene tower in the styrene production unit, allowing the subsequent decommissioning of the benzene / toluene tower to offset energy losses. Compared to the original uncoupled process, the overall energy consumption of the coupled coking crude benzene hydrogenation unit and the styrene unit is reduced by approximately 35%. BRIEF DESCRIPTION OF THE DRAWINGS

[0078] Figure 1 This is a flow chart of the traditional coking crude benzene hydrogenation oil separation process in the prior art.

[0079] Figure 2 The present invention is a process flow chart for producing styrene by catalytic dehydrogenation of ethylbenzene in the prior art.

[0080] Figure 3 This is a process flow chart of hydrogenation separation of coking crude benzene in Example 1 of the present invention.

[0081] Figure 4 This is a process flow chart for hydrogenation separation of coking crude benzene in Example 2 of the present invention.

[0082] Figure 5 This is a process flow chart for hydrogenation separation of coking crude benzene in Example 3 of the present invention.

[0083] Reference numerals

[0084] 1- light benzene separation tower, 2- tail gas tower, 3- benzene product tower, 4- solvent oil product tower. DETAILED DESCRIPTION

[0085] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention. It is obvious that the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0086] Example 1

[0087] This embodiment provides a coking crude benzene hydrogenation separation system coupled with a styrene unit, such as Figure 3 As shown, the system includes a light benzene separation tower 1, a tail gas tower 2, a benzene product tower 3, and a solvent oil product tower 4:

[0088] The light benzene separation tower 1 has a feed inlet located in the lower middle portion of the light benzene separation tower 1 for injecting hydrogenated oil, benzene / toluene fractions from the styrene production unit, and a small amount of aromatic components returned from the subsequent benzene product tower 3; a tower top outlet for sending out aromatic hydrocarbons below C7, non-aromatic hydrocarbons, and inorganic components (such as hydrogen sulfide, ammonia, water vapor, etc.); a tower bottom outlet, located at the bottom of the light benzene separation tower 1, for outputting aromatic hydrocarbons and non-aromatic hydrocarbon components above C7;

[0089] The tail gas tower 2 has a feed port located in the lower middle portion of the tail gas tower 2, the feed port being connected to the top outlet of the light benzene separation tower 1; the top outlet is used to deliver non-condensable tail gas (including inorganic components and C1-C6 non-aromatic hydrocarbons, etc.); the bottom outlet is located at the bottom of the tail gas tower 2, and is used to deliver the bottom liquid whose main components are benzene, a small amount of toluene, and a small amount of C4-C8 non-aromatic hydrocarbons;

[0090] The benzene product tower 3 has a feed port located in the lower middle portion of the benzene product tower 3, the feed port being connected to the bottom outlet of the tail gas tower 2; a tower top outlet for extracting a product consisting of C4-C7 non-aromatic hydrocarbons and a small amount of benzene; a side outlet for outputting a benzene product containing a small amount of C4-C7 non-aromatic hydrocarbons to the alkylation reactor of benzene and ethylene in the styrene production unit or to an intermediate tank for storage or mixing ( Figure 2 The bottom outlet is located at the bottom of the benzene product tower 3, which is used to extract the bottom liquid of the aromatic components mainly benzene and a small amount of toluene, and output it to the feed port of the light benzene separation tower 1 or the hydrogenation oil mixing intermediate tank ( Figure 3 not shown);

[0091] The solvent oil product tower 4 has a feed port located in the middle of the solvent oil product tower 4, and the feed port is connected to the bottom outlet of the light benzene separation tower; the top outlet is used to produce a solvent oil product containing a mixture of toluene and xylene containing a small amount of C6-C8 non-aromatic hydrocarbons; the bottom outlet is located at the bottom of the solvent oil product tower 4, and is used to output heavy aromatic solvent oil products above C9.

[0092] The coking crude benzene hydrogenation separation process is implemented by using the above-mentioned coking crude benzene hydrogenation separation system coupled with a styrene production unit, which specifically includes the following steps:

[0093] S1. The hydrogenated oil obtained after the hydrogenation of the coking crude benzene is uniformly mixed with the benzene / toluene material returned from the styrene production process and / or a small amount of aromatic components returned from the subsequent benzene product tower 3, and then input into the light benzene separation tower 1. After treatment, the aromatic hydrocarbons, non-aromatic hydrocarbons and inorganic components below C7 are extracted from the top outlet of the light benzene separation tower 1 and enter the tail gas tower 2; the aromatic hydrocarbons and non-aromatic hydrocarbon components above C7 are transported from the bottom outlet of the light benzene separation tower 1 to the solvent oil product tower for treatment; in order to ensure the maximum yield of the benzene product, the toluene content in the top product of the light benzene tower 1 is controlled to be 5wt%-0.1wt% to ensure that all the benzene is evaporated.

[0094] S2. Aromatic hydrocarbons below C7, non-aromatic hydrocarbons, and inorganic components extracted from the top outlet of light benzene separation tower 1 are processed in tail gas tower 2. Inorganic substances and non-condensable tail gases such as C1-C6 non-aromatic hydrocarbons are separated from the top outlet of tail gas tower 2. The bottom liquid, which mainly consists of benzene, a small amount of toluene, and C4-C8 non-aromatic hydrocarbons, is transported from the bottom outlet of tail gas tower 2 to benzene product tower 3 for treatment.

[0095] S3. The bottom liquid of tail gas tower 2 is processed by benzene product tower 3, and a product composed of C4-C7 non-aromatic hydrocarbons and a small amount of benzene is extracted from the top outlet of benzene product tower 3; a benzene product with a purity of more than 99.5% containing trace amounts of C4-C7 non-aromatic hydrocarbons is extracted from the side outlet of benzene product tower 3 and transported to Figure 2 The alkylation reactor in the styrene production unit serves as the feedstock for the styrene production process (alkylation reaction of benzene and ethylene). A bottoms liquid, primarily composed of benzene and a small amount of toluene, is extracted from the bottoms outlet of the benzene product column 3 and transferred to a hydrogenation oil mixing intermediate tank (not shown). The liquid then enters the light benzene separation column 1 for continuous recovery of the benzene product. During operation of the benzene product column 3, toluene accumulates continuously in the bottoms liquid. Since styrene has strict requirements for toluene content, to prevent toluene from entering the benzene product, the toluene content in the bottoms liquid of the benzene product column 3 must be kept below 20 wt %. When the toluene content reaches 20 wt %, the bottoms liquid is transferred to the hydrogenation oil mixing intermediate tank and then re-enters the light benzene separation column 1 for continuous toluene recovery.

[0096] S4. Aromatic and non-aromatic components above C7 output from the light benzene separation tower 1 are processed in the solvent oil product tower 4. A mixture of toluene and xylene containing a small amount of C6-C8 non-aromatics is extracted from the top outlet of the solvent oil product tower 4 and sold as a solvent oil product or gasoline additive product. The bottom outlet of the solvent oil product tower 4 outputs a heavy aromatic solvent oil product above C9, mainly composed of trimethylbenzene, naphthalene, tetralin and polycyclic aromatic hydrocarbons. This product can be used in the ink, pharmaceutical and resin industries.

[0097] Table 1 below shows the operating conditions of each tower during actual production of the coking crude benzene hydrogenation separation process coupled with a styrene unit.

[0098] Table 1 Main operating conditions and flow rates of each tower

[0099]

[0100] Table 2 below shows the specific mass percentages of the main components of the input and output materials of each tower under the above conditions.

[0101] Table 2 Main component contents of feed tower materials and discharge materials from each tower (wt%)

[0102]

[0103] The non-aromatic hydrocarbons contained in the benzene product obtained by the above process are mainly cyclohexane and methylcyclohexane, with a total of ≤0.5 wt%. The boiling points of benzene and non-aromatic hydrocarbons such as cyclohexane are relatively close, and they can only be separated by extraction, and cyclohexane and methylcyclohexane have no effect on the alkylation of styrene. In order to make the benzene and toluene products have higher purity, the traditional process must separate cyclohexane and methylcyclohexane by extractive distillation, which consumes a lot of energy. The present invention transports the side-collected benzene product with a purity of more than 99.57 wt% to Figure 2 In the styrene production unit, cyclohexane and methylcyclohexane in the benzene product are ultimately Figure 2 The tail gas tower of the styrene unit is discharged. Figure 2 The benzene / toluene tower of the styrene unit can be shut down and the materials can be sent to the benzene hydrogenation separation unit for separation.

[0104] exist Figure 3 The non-aromatic hydrocarbons extracted from the top outlet of the benzene production tower are primarily pentane, which has a boiling point of approximately 36°C, significantly different from the boiling point of benzene at 80°C. Pentane can be separated very well, containing only about 10 wt% benzene. In contrast, the non-aromatic hydrocarbon products produced by traditional separation processes contain between 15 wt% and 40 wt% benzene, and downstream manufacturers primarily use it to separate pentane.

[0105] Example 2

[0106] like Figure 4 As shown, this embodiment, based on Example 1, adds a steam generator to the pipeline connecting the top outlet of the light benzene separation tower and the feed inlet of tail gas tower 2. The top operating pressure of the light benzene separation tower is increased from 0.064 MPaG to 0.8 MPaG, causing the top temperature to rise from 108°C to 165°C. The temperature of the bottom of the tower is 185°C and the pressure is 0.844 MPaG. Adding this step can recover more than 50% of the heat energy of the tower, and 0.2 MPaG of steam can be produced as a by-product at the top of the tower, further saving energy and reducing consumption. Other conditions remain unchanged.

[0107] Example 3

[0108] like Figure 5As shown, this embodiment is based on Example 2, in which a steam generator II and a benzene product logistics pipeline for extraction from the top of the benzene product tower 3 are added above the top outlet, and the pentane product flow is changed, specifically:

[0109] The lower part of the benzene product tower 3 has a feed inlet, a top outlet at the top of the tower, a side outlet at the side of the tower, and a kettle outlet at the bottom of the tower. The feed inlet is connected to the kettle outlet of the tail gas tower 2. The top outlet is connected to the steam generator II, the reflux tank, and the cooler in sequence. The cooler is connected back to the reflux tank. The bottom of the reflux tank has a bottom outlet. The bottom outlet of the reflux tank and the side outlet of the benzene product tower 3 are connected together Figure 2 In the alkylation reactor of benzene and ethylene in the styrene production unit, the bottom outlet of the benzene product tower 3 is connected to the feed inlet of the light benzene separation tower 1.

[0110] The coking crude benzene hydrogenation separation system coupled with the styrene production unit is used to implement the coking crude benzene hydrogenation separation process. The separation procedures of the light benzene separation tower, tail gas tower, and solvent oil product tower are the same as those in Example 2. The benzene product tower treatment procedure is changed to:

[0111] The tail gas tower bottom liquid is treated by the benzene product tower, and a mixed gas of C4-C7 non-aromatic hydrocarbons (pentane product) and benzene is extracted from the top outlet of the benzene product tower; the mixed gas is sequentially sent to the cooler through steam generator II and a reflux tank for condensation to separate liquid benzene and gaseous pentane product; the gaseous pentane product is cooled and liquefied again by a secondary cooler (not shown) and then enters a product tank (not shown); the liquid benzene is refluxed into the reflux tank, and the benzene product is output through the bottom outlet of the reflux tank to the styrene production unit for use as a raw material for the styrene production process (the purity of the benzene product can reach 99.5 wt% or more); at the same time, the side extraction port of the benzene product tower is opened or closed, and when opened, the benzene product is output to the styrene production unit for use as a raw material for the styrene production process (the purity of the benzene product can also reach 99.5 wt% or more); the bottom liquid of which the main component is benzene is extracted from the bottom outlet of the benzene product tower, and the bottom liquid is output to the light benzene separation tower through the bottom outlet of the benzene product tower to continuously recover the benzene product.

[0112] When the side outlet of the benzene product tower is closed, the operating pressure at the top of the benzene product tower rises from 0.064MpaG to 1.2MpaG, and the temperature rises from 71℃ to 173℃; the operating pressure at the bottom of the tower rises from 0.08Mpag to 1.30Mpag, and the temperature rises from 130℃ to 255℃; the top steam generator II produces 0.2Mpag of low-pressure steam as a by-product.

[0113] When the amount of light components in the hydroprocessed oil increases and the benzene product tower process cannot be adjusted in time, a side draw outlet is opened, reducing the overhead benzene product output. Pentane product output is temporarily increased to ensure a stable supply of raw materials for the styrene production unit. The benzene product tower overhead operates at a pressure of 1.2 MPaG and a temperature of 170°C; the side draw outlet operates at a pressure of 1.22 MPaG and a temperature of 181°C; and the bottom of the tower operates at a pressure of 1.30 MPaG and a temperature of 255°C. After the short-term adjustments, the overhead benzene product will continue to be used exclusively, and heat recovery from the by-product steam will continue.

[0114] The above embodiments are merely exemplary embodiments of the present application and are not intended to limit the scope of the present application. The scope of protection of the present application is defined by the claims. Those skilled in the art may make various modifications or equivalent substitutions to the present application within the essence and scope of protection of the present application, and such modifications or equivalent substitutions shall also be deemed to fall within the scope of protection of the present application.

Claims

1. A coking crude benzene hydrogenation separation system coupled with a styrene production unit, characterized in that: The coking crude benzene hydrogenation separation system comprises: Light benzene separation tower, with A feed inlet is located in the lower middle portion of the light benzene separation tower, and is used to inject coking crude benzene hydrogenation oil, benzene / toluene fractions from a styrene production unit, and aromatic components returned from a subsequent benzene product tower; The top outlet is used to send out aromatic hydrocarbons below C7, non-aromatic hydrocarbons and inorganic components; and The tower bottom outlet is located at the bottom of the light benzene separation tower, and is used to output aromatic hydrocarbons and non-aromatic hydrocarbon components above C7; Tail gas tower, with A feed inlet is located in the lower middle portion of the tail gas tower and is connected to the top outlet of the light benzene separation tower; The tower top outlet is used to send out non-condensable tail gas; and A tower bottom outlet is located at the bottom of the tail gas tower and is used to output the tower bottom liquid; Benzene product tower, with A feed inlet is located in the lower middle portion of the benzene product tower, and the feed inlet is connected to the outlet of the tail gas tower kettle; The top outlet is used to produce C4-C7 non-aromatic hydrocarbons; The side outlet is used to output the benzene product to the styrene production unit as a raw material for styrene production; The bottom outlet is located at the bottom of the benzene product tower, and is used to extract the bottom liquid containing aromatic hydrocarbons and output it to the feed inlet of the light benzene separation tower; Solvent oil product tower, with A feed inlet is located in the middle of the solvent oil product tower and is connected to the kettle outlet of the light benzene separation tower; The outlet at the top of the tower is used to produce solvent oil products; The tower bottom outlet is located at the bottom of the solvent oil product tower and is used to output heavy aromatic solvent oil products above C9.

2. The coking crude benzene hydrogenation separation system coupled with a styrene production unit according to claim 1, characterized in that: A steam generator is provided on the pipeline connecting the top outlet of the light benzene separation tower and the feed inlet of the tail gas tower.

3. The coking crude benzene hydrogenation separation system coupled with a styrene production unit according to claim 1, characterized in that: A mixed gas of C4-C7 non-aromatic hydrocarbons and benzene is produced from the top outlet of the benzene product tower. The coking crude benzene hydrogenation separation system also includes a processing device for processing the mixed gas of C4-C7 non-aromatic hydrocarbons and benzene produced from the top outlet of the benzene product tower, which includes: Steam generator II, which is connected to the top outlet of the benzene product tower and is used to heat exchange and cool the mixed gas of C4-C7 non-aromatic hydrocarbons and benzene produced from the top outlet of the benzene product tower; a reflux drum connected to the steam generator II and having a bottom outlet, wherein the bottom outlet and the benzene product tower side outlet are connected to the styrene production unit for outputting the benzene product to the styrene production unit; A cooler is arranged above the reflux tank and connected back to the reflux tank. The cooler condenses the C4-C7 non-aromatic hydrocarbons extracted from the top outlet of the benzene product tower to separate liquid benzene and gaseous C4-C7 non-aromatic hydrocarbons, and refluxes the liquid benzene to the reflux tank.

4. The coking crude benzene hydrogenation separation system coupled with a styrene production unit according to claim 3, characterized in that: The processing equipment for processing the mixed gas of C4-C7 non-aromatic hydrocarbons and benzene extracted from the top outlet of the benzene product tower also includes a secondary cooler, which is arranged above the cooler to receive the gaseous C4-C7 non-aromatic hydrocarbons discharged from the cooler and is used for cooling and liquefying the gaseous C4-C7 non-aromatic hydrocarbons.

5. The coking crude benzene hydrogenation separation system coupled with a styrene production unit according to any one of claims 1 to 4, characterized in that: The coking crude benzene hydrogenation separation system also includes a processing device for treating the non-condensable tail gas discharged from the top outlet of the tail gas tower, which includes: A cooling device connected to the top outlet of the tail gas tower, used for cooling and liquefying the organic material in the tail gas; Reflux drum 1, which receives the cooling device to cool the liquefied organic material; and The waste gas treatment system receives and treats the non-condensable gas cooled by the cooling device.

6. The coking crude benzene hydrogenation separation system coupled with a styrene production unit according to any one of claims 1 to 4, characterized in that: The coking crude benzene hydrogenation separation system further includes an intermediate tank I, which is arranged upstream of the light benzene separation tower and connected to the feed port of the light benzene separation tower, and is used to store and / or mix hydrogenated oil, benzene / toluene fractions from the styrene production unit, and aromatic components returned from the subsequent benzene product tower; The coking crude benzene hydrogenation separation system also includes an intermediate tank II, which is connected to the side outlet of the benzene product tower and the bottom outlet of the reflux tank II to receive the benzene product from the side outlet of the benzene product tower and the bottom outlet of the reflux tank II, and is connected to the styrene production unit.

7. A coking crude benzene hydrogenation separation process coupled with a styrene production process, characterized in that: The coking crude benzene hydrogenation separation process is one of the following methods: Method 1: Using the coking crude benzene hydrogenation separation system according to claim 1 or 2, comprising the following steps: S1. The hydrogenated oil obtained after hydrogenation of the coking crude benzene is mixed with the benzene / toluene material returned from the styrene production process and / or the aromatic components returned from the subsequent benzene product column, and then fed into the light benzene separation column. After treatment, aromatic hydrocarbons below C7, non-aromatic hydrocarbons, and inorganic components are extracted from the top outlet of the light benzene separation column and enter the tail gas column; aromatic hydrocarbons above C7 and non-aromatic hydrocarbons are transported from the bottom outlet of the light benzene separation column to the solvent oil product column for treatment; S2. The aromatics, non-aromatics, and inorganic components below C7 extracted from the light benzene separation tower are processed by the tail gas tower, and the non-condensable tail gas is separated from the tail gas tower top outlet. The bottom liquid is transported to the benzene product tower through the tail gas tower bottom outlet for processing; S3. The tail gas column bottoms liquid is processed in the benzene product column, and C4-C7 non-aromatic hydrocarbons are produced from the top outlet of the benzene product column. Benzene product is produced from the side outlet of the benzene product column and transported to the styrene production unit for use as a feedstock in the styrene production process. Aromatic hydrocarbon components are produced from the bottom outlet of the benzene product column, and the bottoms liquid is transported to the light benzene separation column through the bottom outlet of the benzene product column to continuously recover the benzene product. S4. After the aromatic and non-aromatic components above C7 are processed in the solvent oil product column, a solvent oil product is produced from the top outlet of the solvent oil product column; and a solvent oil product with heavy aromatic components above C9 is produced from the bottom outlet of the solvent oil product column; Method 2: Using the coking crude benzene hydrogenation separation system according to claim 3 or 4, comprising the following steps: S1 '. The hydrogenated oil obtained after the hydrogenation of the coking crude benzene is qualified, and the benzene / toluene material returned from the styrene production process and / or the aromatic components returned from the subsequent benzene product tower are mixed and input into the light benzene separation tower. After treatment, aromatic hydrocarbons below C7, non-aromatic hydrocarbons and inorganic components are extracted from the top outlet of the light benzene separation tower and enter the tail gas tower; the aromatic and non-aromatic components above C7 are transported to the solvent oil product tower at the kettle outlet of the light benzene separation tower for treatment; S2 'from the light benzene separation tower top outlet produced C7 below aromatics, non-aromatics and inorganic components, after the tail gas tower treatment, the tail gas tower top outlet separated from the non-condensable tail gas, the bottom liquid through the tail gas tower bottom outlet transported to the benzene product tower treatment; S3'. The tail gas tower bottom liquid is processed by the benzene product tower, and a mixed gas of C4-C7 non-aromatic hydrocarbons and benzene is extracted from the top outlet of the benzene product tower; the mixed gas is sequentially sent to the cooler through the steam generator II and the reflux tank for condensation to separate liquid benzene and gaseous C4-C7 non-aromatic hydrocarbons. The liquid benzene is refluxed to the reflux tank and the benzene product is output to the styrene production unit through the bottom outlet of the reflux tank; at the same time, the benzene product tower side outlet is opened or closed, and when opened, the benzene product is output to the styrene production unit; the component extracted from the benzene product tower bottom outlet is the aromatic component bottom liquid, and the bottom liquid is output to the light benzene separation tower through the benzene product tower bottom outlet to continuously recover the benzene product; S4'. The aromatic and non-aromatic components above C7 output from the light benzene separation tower are processed by the solvent oil product tower, and the solvent oil product is extracted from the top outlet of the solvent oil product tower; the heavy aromatic solvent oil product above C9 is output from the bottom outlet of the solvent oil product tower.

8. The coking crude benzene hydrogenation separation process according to claim 7, characterized in that: In step S1 or S1', among the components separated by the light benzene separation tower, the aromatic hydrocarbon components below C7 include benzene and toluene; the non-aromatic hydrocarbons below C7 include methane, ethane, propane, butane, pentane, hexane, heptane, cyclohexane, and methylcyclohexane; the inorganic matter includes hydrogen sulfide, ammonia, and water vapor; the aromatic hydrocarbon components above C7 include toluene, mixed xylenes, and aromatic and non-aromatic hydrocarbons above C9; In step S1 or S1', the components extracted from the top of the light benzene separation tower are controlled to contain less than 5 wt% of toluene; In step S2 or S2', the non-condensable tail gas separated from the top outlet of the tail gas tower includes: inorganic matter, C1-C6 non-aromatic hydrocarbons; In step S2 or S2', the bottom liquid transported to the benzene product tower through the tail gas tower bottom outlet contains more than 90 wt% of benzene, and further contains 1 wt% to 10 wt% of toluene and 1 wt% to 5 wt% of C4-C8 non-aromatic hydrocarbons; In step S3 or step S3', the C4-C7 non-aromatic hydrocarbons extracted from the benzene product column contain 5 wt% to 20 wt% of benzene; the C4-C7 non-aromatic hydrocarbons include pentane, hexane, and heptane; In step S3 or step S3', the benzene product output from the side outlet of the benzene product tower and / or the bottom outlet of the reflux tank to the styrene production unit contains 0.1 to 1.0 wt% of C4-C7 non-aromatic hydrocarbons; the C4-C7 non-aromatic hydrocarbons include cyclohexane and methylcyclohexane; In step S3 or step S3', the bottom liquid extracted from the bottom outlet is an aromatic component including benzene and toluene, wherein the toluene content is less than 20 wt%; In step S3', the gaseous C4-C7 non-aromatic hydrocarbons are subjected to secondary cooling and liquefaction in a secondary cooler; In step S4 or S4', the solvent oil product is a mixture of toluene and xylene, and contains 0.5 wt% to 5.0 wt% of C6-C8 non-aromatic hydrocarbons.

9. The coking crude benzene hydrogenation separation process according to claim 7 or 8, characterized in that: In step S1 or S1', When no steam generator is provided on the pipeline connecting the top outlet of the light benzene separation tower and the feed port of the tail gas tower, the top pressure of the light benzene separation tower is 0.05-0.08 MpaG, the temperature is 98-110°C; the bottom pressure is 0.10-0.12 MpaG, the temperature is 145-155°C; A steam generator is provided on the pipeline connecting the top outlet of the light benzene separation tower and the feed inlet of the tail gas tower. The top pressure of the light benzene separation tower is 0.6-0.9 MpaG and the temperature is 160-170°C; the bottom pressure is 0.65-0.95 MpaG and the temperature is 180-188°C. In step S2 or S2', The tail gas tower has a top operating pressure of 0.400-0.500 MPaG and a temperature of 105-115°C; the bottom operating pressure is 0.450-0.500 MPaG and a temperature of 150-165°C; In step S3, the top operating pressure of the benzene product tower is 0.05-0.10 MPaG, and the temperature is 70-90°C; the side extraction operating pressure is 0.055-0.06 MPaG, and the temperature is 80-90°C; the bottom operating pressure is 0.08-0.10 MPaG, and the temperature is 130-150°C; In step S3', The benzene product tower side outlet is closed, the benzene product tower top operating pressure is 0.85-1.20 MPaG, the temperature is 110-185°C; the tower bottom operating pressure is 1.00-1.40 MPaG, the temperature is 170-255°C; The side outlet of the benzene product tower is open. The operating pressure of the top of the benzene product tower is 0.85-1.20 MPaG, and the temperature is 110-185°C; the operating pressure of the side production is 1.00-1.30 MPaG, and the temperature is 120-188°C; the operating pressure of the bottom of the tower is 1.00-1.40 MPaG, and the temperature is 170-255°C; In step S4 or S4', the operating pressure of the top of the solvent oil product tower is 0.06-0.10 MPaG, and the temperature is 120-130°C; the operating pressure of the bottom of the tower is 0.07-0.12 MPaG, and the temperature is 220-253°C.

10. The process for hydrogenation separation of coking crude benzene according to claim 7 or 8, characterized in that: In step S1 or S1', No steam generator is provided on the pipeline connecting the top outlet of the light benzene separation tower and the feed inlet of the tail gas tower. The top pressure of the light benzene separation tower is 0.064 MPaG and the temperature is 108°C; the bottom pressure is 0.108 MPaG and the temperature is 147°C. A steam generator is provided on the pipeline connecting the top outlet of the light benzene separation tower and the feed inlet of the tail gas tower. The top pressure of the light benzene separation tower is 0.7-0.8 MPaG and the temperature is 165-170°C; the bottom pressure is 0.744-0.844 MPaG and the temperature is 185-188°C. In step S2 or S2', the operating pressure of the top of the tail gas tower is 0.470 MPaG and the temperature is 110°C; the operating pressure of the bottom of the tower is 0.490 MPaG and the temperature is 156°C; In step S3, the operating pressure of the top of the benzene product tower is 0.064 MPaG and the temperature is 71°C; the operating pressure of the side extraction is 0.060 MPaG and the temperature is 83°C; the operating pressure of the bottom of the tower is 0.080 MPaG and the temperature is 130°C; In step S3', The benzene product tower side outlet is closed, the benzene product tower top operating pressure is 1.1-1.2 MPaG, the temperature is 170-173°C; the tower bottom operating pressure is 1.25-1.30 MPaG, the temperature is 245-255°C; The side outlet of the benzene product tower is open. The operating pressure of the top of the benzene product tower is 1.1-1.2 MPaG, and the temperature is 170-173°C; the operating pressure of the side production is 1.12-1.22 MPaG, and the temperature is 180-183°C; the operating pressure of the bottom of the tower is 1.25-1.30 MPaG, and the temperature is 245-255°C; In step S4 or 4', the operating pressure of the top of the solvent oil product column is 0.064 MPaG and the temperature is 127°C; the operating pressure of the bottom of the column is 0.078 MPaG and the temperature is 224°C.

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