Styrene tail gas runner adsorption concentration coupling solvent absorption treatment system

Abstract

The utility model discloses a styrene tail gas runner adsorption concentration coupling solvent absorption treatment system, which comprises a runner unit, an absorption tower and a flash evaporation analysis unit which are sequentially connected, a waste gas pipeline is connected with a tail gas inlet of the runner unit, and a concentrated gas outlet of the runner unit is connected with a gas phase inlet at the bottom of the absorption tower; the flash evaporation analysis unit comprises a flash evaporation kettle and a rich liquor reflux washing tower, a rich liquor outlet of the absorption tower is divided into two paths, one path is connected with the flash evaporation kettle through a rich liquor intermediate tank, a lean-rich liquor heat exchanger, a rich liquor-flue gas heat exchanger and a rich liquor electric auxiliary heating heater, and the other path is connected with the flash evaporation kettle through the rich liquor reflux washing tower; a gas phase outlet of the flash kettle is connected with a gas phase inlet of the pregnant solution reflux washing tower; a barren liquor outlet of the flash kettle is connected with an absorbent inlet in the top of the absorption tower. The device is low in investment and operation cost, good in tail gas purification effect, energy-saving, consumption-reducing and high in styrene recovery rate.

Description

Technical Field

[0001] The utility model belongs to the field of VOC tail gas treatment, and relates to resource recovery and utilization of pollutant components in VOC tail gas, in particular to a styrene tail gas rotor adsorption concentration coupled solvent absorption treatment system. Background Art

[0002] Styrene is an important raw material in the industrial sector and is widely used, especially in the fine chemical, pharmaceutical, paint and coating industries. Because styrene is volatile and has a high saturated vapor pressure, it is difficult to capture with water and is prone to escape after capture. Low-concentration styrene gas emissions may occur during production and use, forming large amounts of VOC tail gas, which is harmful to the environment and human health. Furthermore, it is a flammable and explosive gas / liquid that is irritating to the eyes and upper respiratory tract mucosa, and has an anesthetic effect at high concentrations [Lei Yanmei et al. Experimental study on purification of low-concentration styrene waste gas by biofilm packing tower. Chinese Journal of Environmental Engineering, 2006, 7(3):36-39]. Styrene is also one of the important precursors for the formation of PM2.5 [Zhao Lei et al. Development and industrial application of deep purification technology for petrochemical VOC waste gas. Environmental Engineering, 2016, (S1):569-571].

[0003] Currently, styrene tail gas treatment mostly adopts traditional VOC tail gas treatment technologies, mainly including adsorption, combustion, absorption, condensation [Lin Yu. Study on the treatment of styrene waste gas by condensation method and its influence law. Modern Chemical Industry, 2018, 38(10):192-195]. These treatment technologies are relatively mature and have many successful application cases. Traditional treatment methods each have their own advantages, but also have certain limitations.

[0004] The condensation method can realize the resource recovery of polluting components in exhaust gas, but the operating cost is high, the power consumption is large, and the exhaust gas after purification is difficult to meet the standards.

[0005] The absorption method can recycle pollutants in tail gas as resources. However, since the absorption process mainly uses organic solvents, the absorption driving force is small, the purification effect is poor, and the purified tail gas is difficult to meet the standards. The absorbent has a small absorption capacity and the absorbent regeneration cost is high.

[0006] Adsorption is a common treatment method for VOC tail gas, achieving standard emissions. However, for high-concentration, high-volume tail gas, adsorption suffers from short adsorption cycles, frequent adsorption and desorption, high energy consumption, and the saturated adsorbent is classified as hazardous waste. This leads to high adsorbent consumption and disposal costs.

[0007] The combustion method has relatively low operating costs and more thorough treatment, but it requires the provision of auxiliary heat enthalpy, especially for low-concentration tail gas. The carbon auxiliary heat enthalpy consumption is large, the carbon emissions are large, and it also leads to a large amount of styrene resource waste.

[0008] From a theoretical analysis, traditional VOC tail gas treatment technology can be used for styrene tail gas treatment. However, since the styrene component is prone to polymerization and heat generation under certain temperature conditions, there are problems such as polymerization-induced blockage and heat safety when traditional treatment technology is used to treat styrene tail gas. Summary of the Invention

[0009] The purpose of the utility model is to solve the above technical problems and provide a styrene tail gas rotor adsorption concentration coupled solvent absorption treatment system which has a simple system, effectively couples absorption, rotor adsorption and rich liquid reflux, has low investment and operating costs, good tail gas purification effect, energy saving and consumption reduction, and high styrene recovery rate.

[0010] The utility model discloses a styrene tail gas rotor adsorption concentration coupled solvent absorption treatment system, which comprises a rotor unit, an absorption tower and a flash evaporation analysis unit connected in sequence, wherein an exhaust gas pipeline is connected to the tail gas inlet of the rotor unit, the concentrated gas outlet of the rotor unit is connected to the gas phase inlet at the bottom of the absorption tower, and the gas phase outlet of the absorption tower is connected to the exhaust gas pipeline via a demister; the flash evaporation analysis unit comprises a flash kettle and a rich liquid reflux washing tower, and the rich liquid outlet of the absorption tower is divided into two paths, one path is connected to the flash kettle via a rich liquid intermediate tank, a lean-rich liquid heat exchanger, a rich liquid-flue gas heat exchanger, and a rich liquid electric auxiliary heater, and the other path is connected to the flash kettle via a rich liquid reflux washing tower, the gas phase outlet of the flash kettle is connected to the gas phase inlet of the rich liquid reflux washing tower; the lean liquid outlet of the flash kettle is connected to the absorbent inlet at the top of the absorption tower.

[0011] The rotor unit includes two stages of rotors connected in series and corresponding desorption gas heat exchangers, wherein the purified gas outlet of the first-stage rotor is connected to the external exhaust pipe via the second-stage rotor; the concentrated gas outlet of the first-stage rotor is connected to the gas phase inlet of the absorption tower via the first-stage desorption fan and the tower inlet cooler; the concentrated gas outlet of the second-stage rotor is divided into two routes, one route is connected to the exhaust gas pipe, and the other route is connected to the tower inlet cooler.

[0012] The flash kettle comprises at least two stages of flash chambers and a bottom liquid storage tank from top to bottom.

[0013] The upper section of the flash kettle is a primary flash chamber, and the lower section is a secondary flash chamber. The bottom liquid storage tank is divided into a lean liquid tank and a semi-lean liquid tank by at least one overflow plate. The upper part of the primary flash chamber is provided with a reflux rich liquid atomizer and a primary flash atomizer, and the bottom is provided with a primary flash guide plate; the upper part of the secondary flash chamber is provided with a secondary flash atomizer, and a part of the lower part of the secondary flash chamber is located above the semi-lean liquid tank and is provided with a secondary flash guide plate, and the remaining area is connected to the lean liquid tank; the front end of the secondary flash guide plate is inserted into the lean liquid tank; the secondary flash guide plate and the overflow plate separate the semi-lean liquid tank from the secondary flash chamber; the gas phase space above the semi-lean liquid tank is connected to the primary flash chamber via a gas stripping gas guide pipe, and the primary flash chamber is connected to the semi-lean liquid tank via the primary flash guide pipe;

[0014] The rich liquid outlet of the absorption tower is divided into two routes, one route is connected to the first-stage flash atomizer through the rich liquid intermediate tank, the lean-rich liquid heat exchanger, the rich liquid-flue gas heat exchanger, and the rich liquid electric auxiliary heater, and the other route is connected to the reflux rich liquid atomizer; the semi-lean liquid tank is connected to the second-stage flash atomizer through the semi-lean liquid-flue gas heat exchanger and the semi-lean liquid electric auxiliary heater; the lean liquid tank is connected to the liquid holding column.

[0015] The rich liquid outlet at the bottom of the rich liquid reflux washing tower is divided into two routes, one route is connected to the rich liquid atomizer of the flash kettle, and the other route is connected to the rich liquid intermediate tank; the gas phase outlets of the first-level flash chamber and the second-level flash chamber are both connected to the rich liquid reflux washing tower through corresponding demisters.

[0016] The lean liquid outlet at the bottom of the liquid holding column is connected to the absorption liquid inlet of the absorption tower through a lean-rich liquid heat exchanger, and the overflow port at the top is connected to the lean liquid tank in the flash kettle through a lean liquid overflow pipe.

[0017] The lean liquid tank and the semi-lean liquid tank in the flash kettle are both provided with aeration heads.

[0018] The gas phase outlet of the rich liquid reflux washing tower is connected to the flash steam condenser, the condensate outlet of the flash steam condenser is connected to the oil-water separator in front of the pump, the condensate outlet of the oil-water separator in front of the pump is connected to the aeration head in the lean liquid tank and the semi-lean liquid tank in the flash kettle through the condensate tank in front of the vacuum pump, the condensate pump, and the condensate-flue gas vaporizer; the non-condensable gas outlet of the flash steam condenser is connected to the incinerator through the vacuum pump.

[0019] To address the problems in the background technology, the inventors set up a rotor unit, coupled absorption and adsorption, and combined it with an evaporation flash analysis unit to achieve exhaust gas purification and emission standards for artificial stone production lines and recovery of styrene components in the tail gas. The specific improvements are as follows:

[0020] (1) A two-stage rotor unit is set up to adapt to the purification of VOC (styrene) tail gas in different environments. According to the different concentrations of styrene in the exhaust gas, you can choose to open all or individually, which is very flexible. In winter, the temperature is low and the concentration of VOC (styrene) in the VOC (styrene) tail gas is low, so only the first-stage rotor needs to be started. In summer, the temperature is high and the concentration of VOC (styrene) in the VOC (styrene) tail gas is high, so it is necessary to start the two-stage rotor. On the other hand, in summer, the first-stage rotor adsorbs and concentrates to produce a high concentration of the first-stage concentrated gas that enters the absorption tower, which is beneficial to increase the absorption capacity of the unit absorbent for styrene, save the power consumption of the absorption unit, reduce the amount of rich liquid analysis, and reduce the energy consumption of the analysis process. The second-stage rotor adsorption ensures that the exhaust gas meets the standards.

[0021] (2) The flash evaporation analysis unit is equipped with a rich liquid reflux washing tower to achieve rich liquid reflux. The flash evaporation analysis unit includes a flash kettle and a rich liquid reflux washing tower. The rich liquid reflux washing tower is arranged downstream of the flash kettle gas phase outlet. Under the suction action of the vacuum pump, the flash steam after atomization and flash evaporation of the flash kettle enters the rich liquid reflux washing tower through the flash kettle gas phase outlet, and contacts with the rich liquid from the absorption tower sprayed from the top of the tower through the packing layer in countercurrent, exchanging heat and capturing fine droplets.

[0022] Rich liquid reflux has the following benefits: 1) Cooling and cold recovery. Within the rich liquid reflux scrubber, the low-temperature rich liquid directly and countercurrently contacts the flash steam, cooling the flash steam and achieving high cooling efficiency. This results in high cold recovery efficiency for the low-temperature rich liquid. 2) It captures droplets, reducing absorbent loss. Due to surface tension, the rich liquid sprayed into the tower easily fuses on the surface of the sprayed droplets when it encounters fine droplets. 3) It has a stripping effect. When the rich liquid enters the rich liquid reflux scrubber, the flash steam temperature is higher than the rich liquid, and the flash steam pressure is lower than the saturation pressure of the rich liquid (i.e., the rich liquid has reached saturation at atmospheric pressure). As the rich liquid flows downward from the tower, its temperature increases due to direct heat exchange with the flash steam, causing the styrene component in the rich liquid to evaporate continuously. As the flash steam entering from the lower part of the tower flows upward, its temperature decreases, leading to an increasing styrene concentration. 4) It improves the efficiency of condensation and styrene recovery in the condenser. After the flash steam passes through the rich liquid reflux scrubber, the styrene concentration is increased and the steam temperature is significantly reduced, which is beneficial for the condensation and recovery of the styrene component after the condenser; 5) a moisture-enriched layer is formed to improve the styrene flash evaporation effect. After the rich liquid enters the rich liquid reflux scrubber, a low-temperature zone is formed in the tower relative to the entire flash steam pipeline. Because the water vapor partial pressure in the flash steam is much higher than the styrene partial pressure, and the saturated vapor pressure of water is greatly affected by temperature within the operating temperature range (7.381kPa at 40°C and 19.932kPa at 60°C), a large amount of water condenses into the rich liquid. The rich liquid passes through the first-stage flash atomizer and enters the flash kettle for first-stage flash evaporation. Almost all the water in the rich liquid vaporizes and enters the flash steam. After passing through the rich liquid reflux scrubber, most of it is condensed again. This cycle of water causes the water vapor concentration in the first-stage flash steam to increase, and the reflux rich liquid condenses and absorbs more and more water until an equilibrium state of water absorption by the reflux rich liquid is reached. According to experimental verification, when distilling the diethyl phthalate solution that absorbs styrene, adding a certain amount of water to the absorption liquid can significantly improve the distillation effect.

[0023] (3) A multi-layer structure is set up in the flash evaporation kettle to perform multi-stage flash evaporation. A multi-stage flash evaporation chamber is set up in the flash evaporation kettle, and a gas stripping section is set up at the bottom of the kettle. The multi-stage flash evaporation and gas stripping are organically combined to improve the distillation effect of the rich liquid, save space, improve the vacuum pump effect, save the operating cost of the gas pump, and the equipment structure is compact and safe.

[0024] The flash desorption unit's flash evaporation kettle has at least two flash chambers, each connected to a lean liquid tank and a semi-lean liquid tank. The rich liquid is first introduced into the upper, primary flash chamber, where it is flash-evaporated by the primary flash atomizer. The flashed semi-lean liquid then flows through the primary flash guide pipe into the semi-lean liquid tank. The semi-lean liquid is then drawn out, heated by the semi-lean heater, and sent to the lower, secondary flash chamber, where it is sprayed out by the secondary flash atomizer for secondary flash evaporation. The lean liquid then flows through the secondary flash guide plate into the lean liquid tank. The front end of the secondary flash guide plate is inserted below the liquid level in the lean liquid tank, forming a liquid seal that separates the secondary flash chamber from the gas stripping area above the semi-lean liquid tank. This two-stage flash evaporation within a single flash evaporation kettle enhances the desorption process. Furthermore, the primary and secondary flash chambers are isolated from each other, ensuring a consistent flash evaporation effect.

[0025] Aeration heads are installed in the lean liquid tank and semi-lean liquid tank. The condensate from which the non-condensable gases and styrene components are separated after flash evaporation is heated and vaporized by a heater and then introduced into the aeration heads in the form of water vapor. This allows for stripping of the lean liquid tank and semi-lean liquid tank, truly realizing the reuse of the condensate. The introduction of stripping gas enhances airflow within the flash evaporation area, and the flow of stripping gas carries out the styrene gas phase concentrated in the flash evaporation area, diluting the styrene in the gas phase surrounding the atomized droplets, enhancing the volatilization of styrene, and improving flash evaporation efficiency.

[0026] (4) Setting up a liquid holding column to eliminate "cavitation". Taking into account the problem of "cavitation" when the lean liquid is drawn out from the bottom of the flash kettle, a liquid holding column is set up to increase the pressure before the pump to extract the lean liquid. Since the working pressure of the flash kettle is maintained below 4kPa (absolute pressure), which is much lower than the atmospheric pressure, when the lean liquid is directly drawn out from the bottom of the flash kettle through the pump into the absorption-adsorption unit at normal pressure, the pressure difference before and after the pump is large, and the residual styrene components and dissolved water in the lean liquid will produce "cavitation", which not only affects the stability of the pump operation, but also causes the pump blades to be impacted and corroded. Setting up a liquid holding column to draw the lean liquid from the bottom of the liquid holding column into the absorption tower increases the liquid phase pressure at the pump inlet and effectively overcomes the "cavitation" phenomenon.

[0027] (5) Install a vacuum pump, flash steam condenser, and pre-pump oil-water separator. The vacuum pump is used to control the negative pressure of the flash chamber, flash steam condenser, and pre-pump oil-water separator to below 4 kPa absolute pressure. A flash steam condenser is installed upstream of the vacuum pump to cool and condense the flash steam, reduce the flash steam volume, improve the efficiency of the vacuum pump, and reduce the operating cost of the vacuum pump.

[0028] (6) Set up a pre-pump oil-water separator. Control the amount of condensed water discharged from the pre-pump oil-water separator to the condensate tank, increase the oil-water interface level in the pre-pump oil-water separator, and discharge excess water from the condensate. Since part of the water vapor brought in by the tail gas during the absorption process is absorbed by the absorbent, during flash evaporation, the boiling point of water is lower than that of styrene, and the water vaporizes first and enters the flash steam together with the water vapor introduced. After condensation, it enters the condensate, disrupting the water balance of the system, and excess water needs to be discharged. Keeping the amount of condensed water discharged from the pre-pump oil-water separator to the condensate tank constant and raising the oil-water interface to a higher position is conducive to discharging the water absorbed by the absorbent from the tail gas together with the oil phase, thereby reducing the styrene concentration in the water phase and improving the styrene recovery rate. Because the higher the level of the oil-water interface, the more thorough the oil phase separation at the water phase outlet, thereby reducing the styrene concentration in the water vapor circulating into the flash evaporator.

[0029] (7) The condensate tank is connected to the aeration head through a condensate-flue gas vaporizer. The condensate is vaporized and returned to the flash kettle as a stripping gas. Experiments show that when the rich liquid contains a certain amount of water, the styrene desorption rate increases significantly. Since the water vapor partial pressure in the flash steam is much higher than the styrene partial pressure, and the saturated vapor pressure of water is within the operating temperature range and is greatly affected by temperature (7.381 kPa at 40°C and 19.932 kPa at 60°C), the rotary evaporation experiment shows that the maximum desorption rate is achieved when all the water in the rich liquid is evaporated (that is, when the water phase disappears). This technical solution aerates the lean liquid and semi-lean liquid with water vapor for a long time (about 75 kg / h, 3000 m3), with a high gas-liquid ratio of about 200-300:1, which is conducive to further reducing the residual styrene concentration in the lean liquid.

[0030] Beneficial effects:

[0031] This utility model achieves ultra-purified exhaust gas discharge from artificial stone production lines while simultaneously recovering VOC components from the exhaust gas. This approach offers low investment and operating costs, excellent exhaust gas purification, effective coupling of absorption and adsorption, energy savings and consumption reduction, high styrene recovery rates, and environmental friendliness. The utility model achieves a pollutant removal rate of over 99.9% from artificial stone production line exhaust gas, recovers over 98% of the styrene component from styrene exhaust gas, and purifies the exhaust gas for ultra-clean emissions. Absorbent consumption is less than 0.1kg / t-styrene. Compared to distillation processes, this method saves over 50% energy consumption and reduces operating costs by over 50%. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a system diagram of Example 1 of the present utility model.

[0033] Figure 2 This is a Henry constant curve fitted with experimental data from the process of Example 1 of the present invention.

[0034] Among them, 1a: main fan; 1b: first-stage desorption fan; 1c: second-stage desorption fan; 1d: incinerator fan; 1e: high-temperature flue gas exhaust fan; 1f: low-temperature flue gas exhaust fan; 3a: first-stage rotor; 3b: second-stage rotor; 4a: first-stage desorption gas heat exchanger; 4b: second-stage desorption gas heat exchanger; 4c: inlet and outlet gas heat exchanger; 4d: inlet gas cooler; 4e: rich liquid-flue gas heat exchanger; 4f: lean-rich liquid heat exchanger; 4g: inlet lean liquid cooler; 4h: flash steam condenser; 4j: condensate-flue gas vaporizer; 4k: semi-lean liquid-flue gas heat exchanger; 5: rich liquid reflux scrubber; 5-1: flash steam demister; 6: demister; 7 : Absorption tower; 8: Absorption liquid intermediate tank; 9a: Primary spray pump; 9b: Secondary spray pump; 9c: Tertiary spray pump; 9d: Primary flash pump; 9e: Secondary flash pump; 9f: Lean liquid discharge pump; 9g: Auxiliary discharge pump; 9h: Rich liquid reflux pump; 9j: Condensate pump; 10a: Rich liquid electric auxiliary heater; 10b: Semi-lean liquid electric auxiliary heater; 11a: Rich liquid intermediate tank; 11b: Condensate tank before vacuum pump; 12a: Primary flash demister; 12b: Secondary flash demister; 12c: Stripping demister; 13: Flash kettle; 13-1: Reflux rich liquid atomizer; 13-2: Primary flash atomizer; 13-3: Secondary flash atomizer 13-4: First-stage flash distillation guide plate; 13-5: First-stage flash distillation guide pipe; 13-6: Second-stage flash distillation guide plate; 13-7: Gas stripping gas guide pipe; 13-8: Second-stage flash distillation gas guide pipe; 13-9: First-stage flash distillation gas guide pipe; 13-10: Lean liquid tank; 13-11: Semi-lean liquid tank; 13-12: Semi-lean liquid aeration head; 13-13: Lean liquid aeration head; 14: Liquid holding column; 14-1: Lean liquid overflow pipe; 15: Pre-pump oil-water separator; 16: Intermediate oil tank; 17: Vacuum discharge valve; 18: Vacuum pump; 19: Incinerator; 20a: Flue gas exhaust emergency valve; 20b: Rich liquid heating flue gas valve; 20c: Flue gas circulation valve; 20d : Semi-lean liquid heating flue gas valve; 20e: Condensed water vaporization flue gas valve; 20f: Purge gas regulating valve; 20g: First-level high-temperature flue gas valve; 20h: Second-level high-temperature flue gas valve; 20j: Condensed gas inlet valve; 20k: Condensed gas inlet valve; 20m: External exhaust flue gas valve; 20n: Rich liquid heating emergency valve; 20p: First-level rotor air inlet valve; 20q: Second-level rotor air inlet valve; 20r: First-level desorption air valve; 20s: Second-level desorption air valve; 20t: Tail gas check valve; 20u: Second-level tower inlet flue gas valve; 20v: Second-level turbine inlet flue gas valve; 20w: Furnace inlet fresh air valve; 20x: Furnace inlet flue gas main valve; 21: Lower explosion limit detector; 22: Filter. DETAILED DESCRIPTION

[0035] The following is an explanation of the system of the utility model in conjunction with the accompanying drawings:

[0036] See also Figure 1, the system of the utility model is connected in sequence to the rotor unit, the absorption tower 7 and the flash evaporation analysis unit;

[0037] The rotary unit includes two stages of rotary wheels connected in series and corresponding desorbed gas heat exchangers. The purified gas outlet of the first stage rotary wheel 3a is connected to the external exhaust pipe via the second stage rotary wheel 3b; the cooled gas outlet of the first stage rotary wheel 3a is connected back to the first stage rotary wheel 3a via the first stage desorbed gas heat exchanger 4a. Similarly, the cooled gas outlet of the first stage rotary wheel 3b is connected back to the first stage rotary wheel 3a via the first stage desorbed gas heat exchanger 4b. The specific connection relationship and working principle of each component of the rotary unit are prior art and will not be described in detail here. The concentrated gas outlet of the first stage rotary wheel 3a (with a lower explosion limit detector 21) is connected to the gas phase inlet of the absorption tower 7 via the first stage desorption fan 1b, the concentrated gas inlet valve 20j, the inlet and outlet gas heat exchanger 4c, and the inlet cooler 4d; the concentrated gas outlet of the second stage rotary wheel 3b is divided into two routes, one route is connected to the inlet and outlet gas heat exchanger 4c via the second stage flue gas inlet valve 20u, and the other route is connected to the exhaust pipe via the second stage flue gas inlet valve 20v.

[0038] The exhaust gas pipeline is divided into three routes after passing through the main fan 1a. The first and second routes are connected to the desorption gas inlet and exhaust gas inlet of the rotor unit through the first-level desorption air valve 20r and the first-level rotor air inlet valve 20p respectively. The third route is connected to the air inlet of the second-level rotor 3b through the second-level rotor air inlet valve 20q.

[0039] The absorption tower can be a conventional absorption tower, or a conventional absorption tower such as Figure 1 The absorption tower 7 shown has an absorption liquid intermediate tank 8, wherein at least three spray layers are provided from top to bottom in the middle of the absorption tower 7, and each spray layer corresponds to an independent absorption liquid intermediate tank 8; the upper absorption liquid intermediate tank is connected to the lower absorption liquid intermediate tank through a full flow pipe.

[0040] The gas phase outlet of the absorption tower 7 is connected to the incinerator 19 through the demister 6 and the inlet and outlet gas heat exchanger 4c;

[0041] The flash evaporation analysis unit includes a flash evaporation kettle 13 and a liquid holding column 14. The flash evaporation kettle 14 has at least two flash evaporation chambers and a lower storage tank from top to bottom. In this embodiment, the upper section of the flash evaporation kettle 14 is a primary flash evaporation chamber, the lower section is a secondary flash evaporation chamber, and the bottom storage tank is divided into a lean liquid tank 13-10 and a semi-lean liquid tank 13-11 by an overflow plate. The upper part of the primary flash evaporation chamber is provided with a reflux rich liquid atomizer 13-1 and a primary flash atomizer 13-2, and the bottom is a primary flash guide plate 13-4; the upper part of the secondary flash evaporation chamber is provided with a secondary flash atomizer 13-3, and a part of the lower part of the secondary flash chamber is located above the semi-lean liquid tank and is provided with a secondary flash evaporation atomizer. The guide plate 13-6 and the remaining area are connected to the lean liquid tank 13-10; the front end of the secondary flash guide plate 13-6 is inserted into the lean liquid tank 13-10; the secondary flash guide plate 13-6 and the overflow plate separate the semi-lean liquid tank 13-11 from the secondary flash chamber; the gas phase space above the semi-lean liquid tank 13-11 is connected to the primary flash chamber via the gas stripping gas guide pipe 13-7, and the primary flash chamber is connected to the semi-lean liquid tank 13-11 via the primary flash guide pipe 13-5;

[0042] The rich liquid outlet of the absorption tower 7 is divided into two routes: one route is connected to the first-stage flash atomizer 13-2 via the rich liquid intermediate tank 11a, the first-stage flash pump 9d, the lean-rich liquid heat exchanger 4f, the rich liquid-flue gas heat exchanger 4e, and the rich liquid electric auxiliary heater 10a; the other route is connected to the reflux rich liquid atomizer 13-1 of the flash kettle 13 via the rich liquid reflux tower 5 and the rich liquid reflux pump 9h. The semi-lean liquid tank 13-11 is connected to the second-stage flash atomizer 13-3 via the second-stage flash pump 9e, the semi-lean liquid-flue gas heat exchanger 4k, and the semi-lean liquid electric auxiliary heater 10b. The lean liquid tank 13-10 is connected to the liquid holding column 14. The gas phase outlets of the first-stage and second-stage flash chambers are connected to the rich liquid reflux tower 5 and the flash steam condenser 4h via the corresponding first-stage flash demister 12a and second-stage flash demister 12b, respectively.

[0043] The condensate outlet of the flash steam condenser 4h is connected to the pre-pump oil-water separator 15. The condensate outlet of the pre-pump oil-water separator 15 is connected to the lean liquid aeration head 13-13 in the lean liquid tank 13-10 and the semi-lean liquid aeration head 13-12 in the semi-lean liquid tank 13-11 in the flash kettle 13 via the pre-exhaust pump condensate tank 11b, the condensate pump 9j, and the condensate-flue gas vaporizer 4j. The non-condensable gas outlet of the flash steam condenser 4h is connected to the incinerator 19 via the inlet and outlet tower gas heat exchanger 4c.

[0044] The lean liquid outlet at the bottom of the liquid holding column 14 is connected to the absorption liquid inlet of the upper section of the absorption tower 7 through the lean-rich liquid heat exchanger 4e and the lean liquid cooler 4g, and the overflow port at the top is connected to the lean liquid tank 13-10 in the flash kettle 13 through the lean liquid overflow pipe 14-1.

[0045] The high-temperature flue gas outlet of the incinerator 19 is divided into two paths, which are respectively merged into one path after passing through the desorber heat exchangers corresponding to the two-stage wheels (the first-stage desorbed gas heat exchanger 4a and the second-stage desorbed gas heat exchanger 4b), and then divided into three paths after passing through the high-temperature flue gas exhaust fan 1e. The first path is connected to the external exhaust pipe through the semi-lean liquid-flue gas heat exchanger 4k, the second path is connected to the external exhaust pipe through the condensed water-flue gas vaporizer 4j, and the third path is divided into two paths after passing through the rich liquid-flue gas heat exchanger 4e, one path is connected to the incinerator 19 through the flue gas circulation valve 20c, and the other path is connected to the external exhaust pipe through the external flue gas valve 20m.

[0046] The low-temperature flue gas outlet of the incinerator 19 is divided into two paths through 1f, one path is connected to the rich liquid-flue gas heat exchanger 4e, and the other path is connected to the external discharge pipeline through the flue gas external discharge emergency valve 20a.

[0047] Process:

[0048] For example, a local artificial stone production plant has four artificial stone production lines. The VOC production units mainly come from mixing, feeding, unloading, spreading, vacuuming, pressing, film removal, and drying. The main pollutants include styrene and non-methane hydrocarbons. During the collection process, the amount of styrene-rich tail gas is 95,000-105,000 Nm 3 / h, the concentration of styrene in exhaust gas is 1500-2000mg / Nm3 in summer 3 , 300-500mg / Nm in winter 3 The heat enthalpy required by the exhaust gas purification system is provided by the system itself.

[0049] refer to Figure 1 The implementation process is divided into two different working conditions: summer and winter. The specific operations are as follows:

[0050] Summer: The temperature is high in summer, and the concentration of styrene in the exhaust gas from the production line is high, 1500-2000mg / Nm 3 .

[0051] 1) Wheel adsorption

[0052] Close the secondary rotor air inlet valve 20q, and the styrene tail gas on the production line is collected and blown into the primary rotor 3a through the exhaust pipe under the suction action of the main fan 1a, and enters the secondary rotor 3b after adsorption, and is further adsorbed and purified before being discharged.

[0053] 2) Desorption

[0054] While the primary and secondary rotors 3a and 3b are adsorbing, the primary and secondary desorption valves 20r and 20s are opened. The desorbed gas, drawn by the primary and secondary desorption fans 1b and c, cools the rotors. The cooled gas then enters the primary and secondary desorption heat exchangers 4a and 4b, respectively, for indirect heat exchange with the approximately 850°C flue gas drawn from the incinerator 19. The desorbed gas temperature rises to approximately 210°C before entering the rotors for desorption. The desorbed gas exiting the primary rotor 3a, the primary concentrated gas, enters the absorption tower 7.

[0055] The concentration of styrene in the first-stage concentrated gas is monitored in real time by the lower explosion limit detector 21, and the concentration of styrene in the first-stage concentrated gas is controlled at 11-12 g / Nm 3 between.

[0056] The secondary concentrated gas from the secondary runner 3b is divided into two parts, which are adjusted according to the styrene concentration in the primary concentrated gas monitored by the secondary tower flue gas valve 20u and the secondary turbine flue gas valve 20v according to the lower explosion limit detector 21. The secondary turbine flue gas valve 20v is kept in a normally open state. 3 When the secondary flue gas valve into the tower is opened by 20u, the secondary concentrated gas is added for dilution. When the concentration is lower than 11g / Nm 3 When , close the secondary flue gas valve 20u into the tower.

[0057] 3) Concentrated gas absorption tower absorption

[0058] Under the suction effect of the first-stage desorption fan 1b, the styrene concentration is 11000-12000 mg / Nm 3 The first-stage concentrated gas and part of the second-stage concentrated gas are introduced into the absorption tower 7.

[0059] The concentrated gas enters the tower from the lower air inlet of the absorption tower 7 and contacts the absorption liquid (diethyl phthalate absorbent) sprayed from the upper part of the tower in countercurrent, and most of the styrene components in the concentrated gas are absorbed.

[0060] The concentrated gas from the absorption tower 7 enters the demister tower 6 to remove the mist droplets and is mixed with the non-condensable gas discharged by the vacuum pump 18, and then enters the incinerator 19 to be burned for heat.

[0061] The absorption process is as follows:

[0062] ① The absorption liquid is sprayed into the tower in three layers. The absorbent from the flash evaporation and desorption unit is mixed with the absorption liquid extracted from the upper layer of the absorption liquid intermediate tank 8 by the first-level spray pump 9a and sprayed into the absorption tower 7 together. The absorption liquid contacts the concentrated gas in countercurrent through the upper packing layer, and part of the styrene component in the concentrated gas is absorbed; the lean liquid and the supplementary fresh absorbent / liquid (diethyl phthalate) are added through the pump head of the first-level spray pump 9a.

[0063] ② The absorption liquid flowing through the upper packing layer flows back into the upper layer of the absorption liquid intermediate tank 8 and is circulated and sprayed through the first-level spray pump 9a; an overflow pipe is set on the upper layer of the absorption liquid intermediate tank 8, and the excess absorption liquid flows to the lower layer of the absorption liquid intermediate tank 8 through the overflow pipe.

[0064] ③ The absorption liquid in the lower layer of the absorption liquid intermediate tank 8 is sprayed into the absorption tower 7 through the secondary spray pump 9b, and contacts with the concentrated gas in countercurrent through the middle packing layer, and part of the styrene component in the concentrated gas is absorbed.

[0065] ④ The absorption liquid flowing through the middle packing layer flows into the lower storage tank of the absorption tower 7 and is circulated and sprayed through the secondary spray pump 9b; an overflow pipe is set in the middle layer of the absorption liquid intermediate tank 8, and the excess absorption liquid flows to the lower storage tank of the absorption tower 7 through the overflow pipe.

[0066] ⑤ A portion of the absorption liquid in the liquid storage tank at the lower part of the absorption tower 7 is sprayed into the absorption tower 7 through the three-stage spray pump 9c, and contacts with the concentrated gas in countercurrent through the lower packing layer, and part of the styrene component in the concentrated gas is absorbed.

[0067] ⑥ The absorption liquid flowing through the lower packing layer enters the lower storage tank of the absorption tower 7 and is circulated and sprayed by the three-stage spray pump 9c; the absorption liquid is sprayed into the absorption tower 7, and contacts with the concentrated gas in countercurrent through the middle packing layer, and part of the styrene component in the concentrated gas is absorbed.

[0068] ⑦ The rich liquid sent to the flash evaporation analysis unit is drawn out through the three-stage spray pump 9c.

[0069] 4) Incineration of concentrated gas from the absorption tower to obtain heat

[0070] The concentrated gas after leaving the absorption tower 7 and being defogged by the demister 6 is introduced into the incinerator 19 for incineration, generating high-temperature flue gas of 850°C and low-temperature flue gas of 110-115°C for heat extraction from the system.

[0071] The concentration of styrene in the concentrated gas leaving the absorption tower 7 and after being defogged by the demister 6 is adjusted according to the heat enthalpy required by the system and controlled at 4000-6000 mg / Nm 3 between.

[0072] When the system enthalpy demand increases, the frequency of the first-stage spray pump 9a is lowered, the first-stage spray volume is reduced, the styrene concentration in the concentrated gas out of the tower is increased, and the heat production of the incinerator 19 is increased; when the system enthalpy demand increases, the frequency of the first-stage spray pump 9a is lowered, the first-stage spray volume is increased, the styrene concentration in the concentrated gas out of the tower is reduced, and the heat production of the incinerator 19 is reduced.

[0073] The styrene concentration in the non-condensable gas exceeds the lower limit of styrene explosion concentration, and is promptly mixed with the concentrated gas from the tower and enters the incinerator 19 for incineration to obtain heat.

[0074] 5) Rich liquid flash evaporation and styrene recovery

[0075] ① The amount of rich liquid drawn from the lower storage tank of the absorption tower 7 into the flash evaporation and desorption unit is 15-20 t / h. The rich liquid is divided into two parts. One part (4-6 t / h) enters the rich liquid reflux washing tower 5, and the remaining part (10-15 t / h) enters the rich liquid intermediate tank 11a. It is then pumped out by the first-stage flash pump 9d and enters the rich liquid-flue gas heat exchanger 4e and the lean-rich liquid heat exchanger 4f in turn for heat exchange and temperature increase, and then enters the flash kettle 13 for the first-stage flash evaporation.

[0076] ② Under the suction action of the vacuum pump, the pressure in the flash kettle 13 is controlled at about 4kPa.

[0077] ③ The rich liquid in the rich liquid intermediate tank 11a is pumped out by the first-stage flash pump 9d and first exchanged with the lean liquid from the flash desorption unit, and then exchanged with the low-temperature flue gas from the incinerator 19, heated to 60-65°C, and then atomized by the first-stage flash atomizer 13-2 and enters the flash kettle 13. Under negative pressure, 30-40% of the styrene component in the rich liquid evaporates into the flash steam, and the semi-lean liquid from which part of the styrene has evaporated flows into the semi-lean liquid tank 13-11 through the first-stage flash guide plate 13-4 and the first-stage flash guide pipe 13-5.

[0078] ④ The semi-lean liquid in the semi-lean liquid tank 13-11 is pumped out by the secondary flash pump 9e and heated to 65-70°C by the semi-lean liquid-flue gas heat exchanger 4k. It is then atomized by the secondary flash atomizer 13-3 and enters the flash kettle 13 for secondary flash evaporation. The styrene component in the semi-lean liquid further evaporates into the flash steam; the lean liquid with about 20-30% of the styrene component remaining is introduced into the lean liquid tank 13-12 through the secondary flash guide plate 13-6.

[0079] ⑤ Water vapor is introduced into the semi-lean liquid tank 13-11 and the lean liquid tank 13-10 through the semi-lean liquid aeration head 13-12 and the lean liquid aeration head 13-13 respectively, so as to further gas strip the lean liquid and the semi-lean liquid, thereby further reducing the styrene concentration in the lean liquid and the semi-lean liquid.

[0080] ⑥ The stripping gas and flash steam are respectively led out through the stripping gas duct 13-7, the secondary flash evaporation duct 13-8, and the primary flash evaporation duct 13-9, and are respectively defogged by the stripping demister 12c, the secondary flash demister 12b, and the primary flash demister 12a, and then enter the rich liquid reflux washing tower 5 under the suction action of the vacuum pump 18.

[0081] ⑦ The lean liquid after flash evaporation is pumped from the lean liquid tank 13-10 into the liquid holding column 14 by the auxiliary discharge pump 9g, and then pumped from the bottom of the liquid holding column 14 by the lean liquid discharge pump 9f. It is cooled to 20-30°C through the lean-rich liquid heat exchanger 4f and the tower lean liquid cooler 4g before entering the absorption tower 7. An overflow pipe 14-1 is provided at the top of the liquid holding column 14 to drain the excess lean liquid back to the lean liquid tank 13-10 to maintain a stable liquid level in the liquid holding column 14.

[0082] ⑧ The cold rich liquid from the absorption tower 7 is sprayed from the upper part of the reflux washing tower 5 into the reflux washing tower 5, and is in countercurrent contact with the flash steam and stripping gas entering from the lower part of the reflux washing tower 5. The rich liquid is heated, and the flash steam and stripping gas are cooled. The cooled flash steam and stripping gas are further demisted by the flash steam demister 5-1 and then enter the flash steam condenser for 4 hours. During the countercurrent contact between the rich liquid, the flash steam and stripping gas, the fine droplets in the flash steam and stripping gas are captured by the rich liquid. The rich liquid after heating and capturing the droplets is atomized by the rich liquid reflux pump for 9 hours and enters the flash kettle 13 for atomization and flash evaporation.

[0083] ⑨ The flash steam and stripping gas entering the flash steam condenser 4h are cooled by a low-temperature refrigerant (7°C low-temperature water), and most of the styrene and water therein are condensed and enter the pre-pump oil-water separator 15 for oil-water separation. The water phase enters the condensate tank 11b, and is then sent to the condensate-flue gas vaporizer 4j through the condensate pump 9j for heating and vaporization to form superheated steam at 60-65°C, which is bubbled into the semi-lean liquid tank 13-11 and the lean liquid tank 13-10; the oil phase, i.e., styrene, is discharged into the intermediate oil tank 16 through the vacuum unloading valve 17 to realize the recovery of the styrene component.

[0084] 6) System heating

[0085] According to the system heat balance analysis, the media that need to be heated include the primary desorbed gas, the secondary desorbed gas, the rich liquid entering the flash kettle 13, and the aeration water vapor. Among them, the primary desorbed gas and the secondary desorbed gas need to be heated from about 100°C after the cooling wheel to 220°C, the rich liquid entering the flash kettle 13 needs to be heated from 20-30°C to 60-65°C, and the aeration water vapor entering the flash kettle 13 needs to be heated from condensed water at 20-30°C to 60-65°C.

[0086] ① The secondary desorbed gas and part of the primary desorbed gas are introduced into the incinerator 19 through the incinerator fan 1d for incineration, generating high-temperature flue gas of 850°C and low-temperature flue gas of 110-115°C.

[0087] ② High-temperature flue gas of 800-850℃ is drawn out from the high-temperature flue gas outlet of the incinerator 19 through the high-temperature flue gas exhaust 1e, with a speed of 5500-6000Nm 3 / h, and is divided into two parts by the first-level high-temperature flue gas valve 20g and the second-level high-temperature flue gas valve 20h, and enters the first-level desorbed gas heat exchanger 4a and the second-level desorbed gas heat exchanger 4b respectively to exchange heat with the first-level desorbed gas and the second-level desorbed gas. The temperature of the desorbed gas is increased from 100℃ to 220℃, and the temperature of the high-temperature flue gas is reduced to 210-250℃;

[0088] ③ The high-temperature flue gas cooled to 210-250℃ is extracted by the high-temperature flue gas exhaust 1e, and is divided into three parts through the semi-lean liquid heating flue gas valve 20d, the condensed water vaporization flue gas valve 20e, and the rich liquid heating emergency valve 20n. One part enters the semi-lean liquid-flue gas heat exchanger 4k to heat the semi-lean liquid, one part enters the condensed water-flue gas vaporizer 4j, and the remaining part is introduced into the incinerator 19 through the incinerator fan 1d for circulation to dilute the concentrated gas entering the furnace.

[0089] ④ Through the low-temperature flue gas exhaust 1f, the low-temperature flue gas of 105-115℃ is drawn out from the low-temperature flue gas outlet of the incinerator 19 with a speed of 13000-14000Nm 3 / h, and is divided into two parts through the regulation of the rich liquid heating flue gas valve 20b and the flue gas discharge emergency valve 20a. One part enters the rich liquid-flue gas heat exchanger 4e to exchange heat with the rich liquid, and the low-temperature flue gas temperature is cooled from 105-115℃ to 60-70℃; the remaining part is discharged from the chimney through the flue gas discharge emergency valve 20a to adjust the flow rate.

[0090] ⑤ The low-temperature flue gas with a temperature of 60-70°C exits the rich liquid-flue gas heat exchanger 4e and is adjusted to flow into the incinerator 19 through the flue gas circulation valve 20c and the exhaust flue gas valve 20m to adjust the amount of circulating flue gas and the amount of exhaust flue gas.

[0091] ⑥ The amount of flue gas discharged from the chimney is adjusted to be as small as possible through the external discharge emergency valve 20a. The amount of primary desorbed gas introduced into the incinerator 19 is adjusted according to the amount of low-temperature flue gas discharged through the external discharge emergency valve 20a. When the amount of low-temperature flue gas discharged through the external discharge emergency valve 20a is large, the amount of primary desorbed gas introduced into the incinerator 19 is reduced until no external discharge is adjusted through the external discharge emergency valve 20a. The amount of primary desorbed gas entering the absorption tower 7 is increased to improve the absorption of styrene.

[0092] 7) Non-condensable gas recovery and treatment

[0093] The pressure in the flash reactor is controlled at 4 kPa, and the amount of gas discharged by the vacuum pump is about 4000 m 3 / h, of which non-condensable gas is 10-20% (according to 60m 3 / h), after being cooled to about 20℃ in the flash steam condenser for 4 hours, the moisture and most of the styrene components in the flash steam are condensed and enter the normal pressure state after leaving the vacuum pump. The volume of non-condensable gas is 2.11m 3 The styrene concentration in the remaining non-condensable gas is high, about 29g / Nm 3The amount of styrene carried out by non-condensable gas is about 60g / h.

[0094] The styrene concentration in the non-condensable gas exceeds the lower limit of styrene explosion concentration, and is promptly mixed with the concentrated gas from the tower and enters the incinerator 19 for incineration to obtain heat.

[0095] 8) Diethyl phthalate is preferably used as the styrene absorbent

[0096] The absorbent used in the method of the utility model is a high-boiling-point organic solvent having a boiling point 100° C. or higher than that of styrene, preferably diethyl phthalate.

[0097] See also Figure 2 The Henry constant of the solution after diethyl phthalate absorbs styrene is: 23.04kg / (moL·kPa).

[0098] The utility model process can recover more than 98% of the styrene components in styrene tail gas, purify the tail gas to meet emission standards, and consume less than 0.1kg / t-styrene. Compared with the distillation process, it saves more than 50% of energy consumption and reduces the recovery cost by more than 50%.

[0099] Winter: The temperature is low in winter, and the concentration of styrene from the tail gas of the production line is low, 300-500mg / Nm 3 .

[0100] During winter operation, only the secondary rotor 3b is opened and the primary rotor 3a is closed, that is, the primary rotor air inlet valve 20p is closed and the secondary rotor air inlet valve 20q is opened. The styrene tail gas on the production line is collected and blown into the secondary rotor 3b for adsorption and purification under the suction action of the main fan 1a and then discharged. At the same time, the absorption and flash evaporation analysis units are shut down, and the rest of the operation process is the same as above.

Claims

1. A styrene tail gas rotor adsorption concentration coupled solvent absorption treatment system, characterized in that: It includes a rotor unit, an absorption tower and a flash evaporation analysis unit connected in sequence, wherein the exhaust gas pipeline is connected to the tail gas inlet of the rotor unit, and the concentrated gas outlet of the rotor unit is connected to the gas phase inlet at the bottom of the absorption tower; the flash evaporation analysis unit includes a flash kettle and a rich liquid reflux washing tower, and the rich liquid outlet of the absorption tower is divided into two routes, one route is connected to the flash kettle through a rich liquid intermediate tank, a lean-rich liquid heat exchanger, a rich liquid-flue gas heat exchanger, and a rich liquid electric auxiliary heater, and the other route is connected to the flash kettle through a rich liquid reflux washing tower, and the gas phase outlet of the flash kettle is connected to the gas phase inlet of the rich liquid reflux washing tower; the lean liquid outlet of the flash kettle is connected to the absorbent inlet at the top of the absorption tower.

2. The styrene tail gas rotor adsorption concentration coupled solvent absorption treatment system according to claim 1, characterized in that: The rotor unit includes two stages of rotors connected in series and corresponding desorption gas heat exchangers, wherein the purified gas outlet of the first-stage rotor is connected to the external exhaust pipe via the second-stage rotor; the concentrated gas outlet of the first-stage rotor is connected to the gas phase inlet of the absorption tower via the first-stage desorption fan and the tower inlet cooler; the concentrated gas outlet of the second-stage rotor is divided into two routes, one route is connected to the exhaust gas pipe, and the other route is connected to the tower inlet cooler.

3. The styrene tail gas rotor adsorption concentration coupled solvent absorption treatment system according to claim 1 or 2, characterized in that: The flash kettle comprises at least two stages of flash chambers and a bottom liquid storage tank from top to bottom.

4. The styrene tail gas rotor adsorption concentration coupled solvent absorption treatment system according to claim 3, characterized in that: The upper section of the flash kettle is a primary flash chamber, and the lower section is a secondary flash chamber. The bottom liquid storage tank is divided into a lean liquid tank and a semi-lean liquid tank by at least one overflow plate. The upper part of the primary flash chamber is provided with a reflux rich liquid atomizer and a primary flash atomizer, and the bottom is provided with a primary flash guide plate; the upper part of the secondary flash chamber is provided with a secondary flash atomizer, and a part of the lower part of the secondary flash chamber is located above the semi-lean liquid tank and is provided with a secondary flash guide plate, and the remaining area is connected to the lean liquid tank; the front end of the secondary flash guide plate is inserted into the lean liquid tank; the secondary flash guide plate and the overflow plate separate the semi-lean liquid tank from the secondary flash chamber; the gas phase space above the semi-lean liquid tank is connected to the primary flash chamber via a gas stripping gas guide pipe, and the primary flash chamber is connected to the semi-lean liquid tank via the primary flash guide pipe; The rich liquid outlet of the absorption tower is divided into two routes, one route is connected to the first-stage flash atomizer through the rich liquid intermediate tank, the lean-rich liquid heat exchanger, the rich liquid-flue gas heat exchanger, and the rich liquid electric auxiliary heater, and the other route is connected to the reflux rich liquid atomizer; the semi-lean liquid tank is connected to the second-stage flash atomizer through the semi-lean liquid-flue gas heat exchanger and the semi-lean liquid electric auxiliary heater; the lean liquid tank is connected to the liquid holding column.

5. The styrene tail gas rotor adsorption concentration coupled solvent absorption treatment system according to claim 4, characterized in that: The rich liquid outlet at the bottom of the rich liquid reflux washing tower is divided into two routes, one route is connected to the rich liquid atomizer of the flash kettle, and the other route is connected to the rich liquid intermediate tank; the gas phase outlets of the first-level flash chamber and the second-level flash chamber are both connected to the rich liquid reflux washing tower through corresponding demisters.

6. The styrene tail gas rotor adsorption concentration coupled solvent absorption treatment system according to claim 4, characterized in that: The lean liquid outlet at the bottom of the liquid holding column is connected to the absorption liquid inlet of the absorption tower through a lean-rich liquid heat exchanger, and the overflow port at the top is connected to the lean liquid tank in the flash kettle through a lean liquid overflow pipe.

7. The styrene tail gas rotor adsorption concentration coupled solvent absorption treatment system according to any one of claims 4 to 6, characterized in that: The lean liquid tank and the semi-lean liquid tank in the flash kettle are both provided with aeration heads.

8. The styrene tail gas rotor adsorption concentration coupled solvent absorption treatment system according to claim 7, characterized in that: The gas phase outlet of the rich liquid reflux washing tower is connected to the flash steam condenser, the condensate outlet of the flash steam condenser is connected to the oil-water separator before the pump, and the condensate outlet of the oil-water separator before the pump is connected to the aeration head in the lean liquid tank and the semi-lean liquid tank in the flash kettle through the condensate tank before the vacuum pump, the condensate pump, and the condensate-flue gas vaporizer.

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