System for recovering styrene from exhaust gas of artificial-stone production line on basis of coupling adsorption and concentration with absorption

Abstract

Disclosed in the present invention is a system for recovering styrene from exhaust gas of an artificial-stone production line on the basis of coupling adsorption and concentration with absorption. The system comprises a rotor unit, an absorption tower and a flash desorption unit which are sequentially connected, wherein an exhaust gas pipeline is connected to a tail gas inlet of the rotor unit; a concentrated gas outlet of the rotor unit is connected to a gas phase inlet at the bottom of the absorption tower; a gas phase outlet of the absorption tower is connected to an incinerator or the exhaust gas pipeline via a demister; a rich liquid outlet of the absorption tower is connected to the flash desorption unit; and a lean liquid outlet of the flash desorption unit is connected to an absorbent inlet at the top of the absorption tower via a liquid holding column. The system of the present invention is simple, effectively couples absorption with rotor adsorption, and has low investment and operation costs, a good tail gas purification effect, energy-saving and consumption-reducing effects, and a high styrene recovery rate.

Description

Styrene recovery system for exhaust gas from artificial stone production lines based on adsorption, concentration, and coupling absorption. Technical Field

[0001] This invention belongs to the field of VOC exhaust gas treatment and relates to a resource recovery and utilization of pollutant components in VOC exhaust gas. Specifically, it is a styrene recovery system for waste gas from artificial stone production lines based on adsorption, concentration, and coupling absorption. Background Technology

[0002] Styrene is an important organic chemical widely used in industries such as plastics, fibers, rubber, coatings, adhesives, and fragrances. However, the production process of styrene will emit a large amount of waste gas, which contains organic substances such as styrene, propylene, and C4 olefins, as well as inorganic substances such as carbon dioxide and nitrogen oxides, which will cause great harm to the environment and human health. Moreover, it is a flammable and explosive gas / liquid, which has an irritating effect on the eyes and upper respiratory tract mucosa, and high concentrations have an anesthetic effect [Lei Yanmei et al. Experimental study on purification of low concentration styrene waste gas by biofilm packed tower. Journal of Environmental Engineering, 2006, 7(3): 36-39]. Styrene is also one of the important precursors to 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]. Therefore, the treatment of styrene waste gas has become an important environmental protection issue.

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

[0004] Condensation is a method suitable for the recovery of high-boiling-point VOCs, enabling the resource recovery of pollutant components in exhaust gas. To achieve high recovery efficiency, the recovery system typically requires high pressure or low temperature, significantly increasing equipment and maintenance costs and power consumption. Furthermore, the purified exhaust gas often fails to meet emission standards and is frequently used in combination with other technologies [Zhang Shangsuo. Research and Analysis of Major Treatment Methods for Volatile Organic Compounds. Regional Governance, 2020].

[0005] Absorption methods mainly utilize low-volatility or non-volatile solvents (mineral oil, water-based compounds, and solvents) to absorb VOCs. This method is suitable for VOCs treatment under low-temperature and high-pressure environments, and its absorption efficiency mainly depends on the absorption capacity of the absorbent and the structural characteristics of the absorption equipment. The advantage of absorption methods is that they can realize the resource recovery of pollutant components in tail gas. Its disadvantages are that the selection of absorbents is relatively difficult, and the absorbents need to be replaced regularly, which complicates the treatment process and increases costs [He Luhong. Study on the absorption effect of Tween aqueous solution on different VOCs. Salt Industry and Chemical Industry, 2016(7):3]. In addition, since the absorption process mainly uses organic solvents, the absorption driving force is small, the purification effect is poor, the purified tail gas is difficult to meet the standards, the absorption capacity of the absorbent is small, and even if the absorbent is regenerated, the regeneration cost is high.

[0006] Adsorption is a common treatment method for VOC exhaust gas. It utilizes substances with adsorption capabilities, such as activated carbon, zeolite molecular sieves, and activated alumina, to adsorb harmful components and eliminate pollution. The adsorbent is the key to adsorption technology. Generally, adsorbents should have abundant pore structure, a large specific surface area, and good chemical and thermal stability. Adsorbents can be broadly classified into three categories: oxygen-containing adsorbents, carbon adsorbents, and polymer adsorbents. Oxygen-containing adsorbents include silica gel, zeolite, and metal oxides; carbon adsorbents are mainly activated carbon; and polymer adsorbents primarily utilize the surface functional groups of polymers to adsorb different pollutants.

[0007] Activated carbon (mainly granular activated carbon) is the most widely used in practical engineering applications. Its porous structure and huge specific surface area can efficiently trap VOCs molecules in waste gas [Yu Qian et al. Research progress on VOCs purification treatment by activated carbon adsorption technology. Materials Research and Application, 2010, 004(004):368-371]. A large number of studies have been conducted at home and abroad on the application of activated carbon in the adsorption of organic pollutants. The main advantages of activated carbon adsorption technology are its high removal efficiency and low operating energy consumption, which can achieve the standard emission of tail gas. The main disadvantages are that the preparation cost of activated carbon is high [Wang Xiaoli et al. Research progress on VOCs removal technology. Guangdong Chemical Industry, 2014, 41(016):106-107]. For high-concentration and large-volume tail gas, the adsorption method has a short adsorption cycle, frequent adsorption and desorption, high operating energy consumption, and the adsorbent after saturation is classified as hazardous waste, resulting in high adsorbent consumption and high disposal costs.

[0008] Combustion is a method that uses combustion oxidation and high-temperature thermal decomposition to break down the structure of VOCs pollutants. The main products after decomposition are CO2 and H2O. Combustion is generally only applicable to the treatment of combustible or decomposable harmful substances at high temperatures. It mainly includes three forms: direct combustion, thermal combustion, and catalytic combustion [Cao Qiuwei et al. Discussion on the treatment of organic waste gas by combustion. Science & Technology Vision, 2012(27):2].

[0009] Direct combustion is generally only suitable for treating exhaust gases with combustible components and high concentrations of pollutants. Because combustion within a certain range of combustible gas concentrations may pose an explosion risk, it is essential to rigorously monitor the gas composition and concentration and implement appropriate safety measures.

[0010] Thermal combustion involves adding auxiliary fuel and burning it together with exhaust gas containing low levels of organic components, resulting in higher operating costs.

[0011] Catalytic combustion is a method that uses a catalyst to oxidize and decompose carbon and oxygen compounds in organic gases into harmless gases and release heat at a relatively low temperature (250-300℃) [Chen Yagang et al. Mechanism and research progress of organic waste gas treatment technology. Guangdong Chemical Industry, 2014, 41(16):2].

[0012] Combustion has relatively low operating costs and provides more thorough treatment, but it requires auxiliary enthalpy, especially for low-concentration exhaust gases. The consumption of carbon auxiliary enthalpy is large, resulting in large carbon emissions and a significant waste of styrene resources. At the same time, catalytic combustion is limited by factors such as easy deactivation or low activity of the catalyst and the high price of the catalyst. Summary of the Invention

[0013] The purpose of this invention is to solve the above-mentioned technical problems and provide a styrene recovery system for artificial stone production line waste gas based on adsorption concentration coupling absorption, which is simple, effectively couples absorption and rotary adsorption, has low investment and operating costs, good exhaust gas purification effect, energy saving and consumption reduction, and high styrene recovery rate.

[0014] This invention relates to a styrene recovery system for waste gas from an artificial stone production line based on adsorption, concentration, and coupling absorption. The system comprises a rotary turbine unit, an absorption tower, and a flash desorption unit connected in sequence. A waste gas pipeline is connected to the tail gas inlet of the rotary turbine unit, and the concentrated gas outlet of the rotary turbine unit is connected to the gas phase inlet at the bottom of the absorption tower. The gas phase outlet of the absorption tower is connected to an incinerator or the waste gas pipeline via a demister. The rich liquid outlet of the absorption tower is connected to the flash desorption unit, and the lean liquid outlet of the flash desorption unit is connected to the absorbent inlet at the top of the absorption tower via a liquid-holding column.

[0015] The rotor unit includes two-stage rotors connected in series and corresponding desorbed gas heat exchangers. The purified gas outlet of the first-stage rotor is connected to the 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 a first-stage desorption fan and an inlet cooler. The concentrated gas outlet of the second-stage rotor is connected to the incinerator or split into two paths, one connected to the waste gas pipeline and the other connected to the inlet cooler.

[0016] The outlet of the primary desorption fan is divided into two paths: one path connects to the tower cooler, and the other path connects to the incinerator.

[0017] The flash evaporation unit includes a flash evaporator, which has at least two flash chambers and a bottom liquid storage tank from top to bottom.

[0018] The upper section of the flash evaporator 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 equipped with a primary flash atomizer, and the bottom is equipped with a primary flash guide plate. The upper part of the secondary flash chamber is equipped with a secondary flash atomizer, and a portion of the lower part of the secondary flash chamber, located above the semi-lean liquid tank, is equipped with a secondary flash guide plate, while 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 lift gas guide pipe, and the primary flash chamber is connected to the semi-lean liquid tank via a primary flash guide pipe.

[0019] The rich liquid outlet of the absorption tower is connected to the first-stage flash atomizer 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; the semi-lean liquid tank is connected to the second-stage flash atomizer via a semi-lean liquid-flue gas heat exchanger and a semi-lean liquid electric auxiliary heater; and the lean liquid tank is connected to a liquid holding column.

[0020] The flash evaporation analysis unit includes a flash evaporator and a rich liquid reflux washing tower. The upper section of the primary flash chamber of the flash evaporator is also equipped with a rich liquid reflux atomizer.

[0021] The rich liquid outlet of the absorption tower is divided into two paths. One path is connected to the first-stage flash atomizer via 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. The other path is connected to the washing liquid inlet of the rich liquid reflux washing tower.

[0022] The rich liquid outlet at the bottom of the rich liquid reflux scrubbing tower is divided into two paths: one path connects to the rich liquid atomizer of the flash evaporator, and the other path connects to the rich liquid intermediate tank.

[0023] The gas phase outlet of the flash evaporator is connected to a flash condenser via a rich liquid reflux scrubbing tower.

[0024] The lean liquid outlet at the bottom of the liquid-holding column is connected to the absorbent inlet of the absorption tower via a lean-rich liquid heat exchanger, and the overflow port at the top is connected to the lean liquid tank inside the flash evaporator via a lean liquid overflow pipe.

[0025] Both the lean liquid tank and the semi-lean liquid tank inside the flash evaporator are equipped with aeration heads.

[0026] The gas phase outlets of both the primary and secondary flash chambers are connected to a flash vapor condenser or a rich liquid reflux scrubbing tower via corresponding demisters.

[0027] The condensate outlet of the flash condenser is connected to the oil-water separator before the pump. The condensate outlet of the oil-water separator before the pump is connected to the aeration heads in the lean liquid tank and the semi-lean liquid tank inside the flash reactor via the condensate tank before the exhaust pump, the condensate pump, and the condensate-flue gas vaporizer.

[0028] The non-condensable gas outlet of the flash condenser is connected to an incinerator or waste gas pipeline via a vacuum pump.

[0029] The high-temperature flue gas outlet of the incinerator is connected to the desorbed gas heat exchanger of the rotary unit. The flue gas outlet of the desorbed gas heat exchanger is divided into three paths after passing through the high-temperature flue gas exhaust fan. The first path is connected to the exhaust pipe via the semi-lean liquid-flue gas heat exchanger. The second path is connected to the exhaust pipe via the condensate-flue gas vaporizer. The third path is further divided into two paths via the rich liquid-flue gas heat exchanger. One path is connected to the RTO incinerator via the flue gas recirculation valve, and the other path is connected to the exhaust pipe.

[0030] The rotor unit includes two-stage rotors connected in series and corresponding desorber heat exchangers. The high-temperature flue gas outlet of the incinerator is divided into two paths, which are merged into one path after passing through the desorber heat exchangers corresponding to the two-stage rotors, and then divided into three paths after passing through the high-temperature flue gas exhaust fan.

[0031] The low-temperature flue gas outlet of the incinerator is also connected to a rich liquid-flue gas heat exchanger.

[0032] The exhaust gas pipes are connected to the exhaust gas inlets of the two-stage rotors of the rotor unit.

[0033] To address the problems existing in the background technology, the inventors have combined absorption and adsorption by setting up a rotating unit, along with a flash unit, to achieve the purification and emission standards of exhaust gas from the artificial stone production line and the recovery of styrene components from the tail gas. The specific improvements are as follows:

[0034] (1) A two-stage rotor unit is set up to adapt to the purification of VOC (styrene) tail gas under different environments. Depending on the concentration of styrene in the exhaust gas, it can be selected to turn on all of them or turn on one of them, which is flexible. In winter, the temperature is low and the concentration of VOC (styrene) in the exhaust 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 exhaust gas is high, so both stages of rotor need to be started. On the other hand, in summer, the first-stage rotor adsorption and concentration produces a high-concentration first-stage concentrated gas that enters the absorption tower, which is conducive to increasing the absorption capacity of styrene per unit absorbent, saving the power consumption of the absorption unit, reducing the amount of rich liquid desorption, and reducing the energy consumption of the desorption process. The second-stage rotor adsorption ensures that the exhaust gas meets the standards.

[0035] (2) Prepare the residual energy of the gas that cannot be concentrated by the incinerator to meet the enthalpy requirements of the internal desorption, distillation and other units of the system. The incinerator provides high-temperature and low-temperature flue gas. The high-temperature flue gas is used to heat the desorbed gas heat exchanger on the rotor and is further reused. The third flue gas is also returned to the incinerator for circulation through the flue gas circulation valve. Its functions are as follows: ① It helps to improve the stability of the combustion of the tail gas entering the incinerator. A suitable circulation volume ensures sufficient low-temperature flue gas generation, thereby guaranteeing adequate heat storage in the incinerator and increasing the temperature of the exhaust gas entering the furnace. Secondly, reasonable adjustment of the circulation volume effectively controls the amount of high-temperature flue gas above 800℃ and low-temperature flue gas at 110℃-120℃ drawn from the incinerator, ensuring optimal heat distribution for each heat exchanger in the rotary adsorption unit and flash desorption unit (a reasonable circulation volume ensures that the styrene content of the high-temperature flue gas above 800℃ and low-temperature flue gas at 110℃-120℃ drawn from the incinerator meets the heat requirements of their respective heating media). Thirdly, reducing the styrene concentration in the concentrated gas entering the incinerator improves the combustion effect of styrene components, which is beneficial for reducing the VOC concentration in the exhaust gas. High-temperature flue gas is used to heat the desorption gas heat exchanger on the rotary drum, realizing multi-stage utilization of flue gas, and the thermal energy of low-temperature flue gas is also effectively recovered and utilized.

[0036] (3) The flash desorption unit is equipped with a rich liquid reflux scrubbing tower to achieve rich liquid reflux. The flash desorption unit includes a flash reactor and a rich liquid reflux scrubbing tower. The rich liquid reflux scrubbing tower is located downstream of the gas phase outlet of the flash reactor. Under the suction of the vacuum pump, the flash steam after flash evaporation in the flash reactor enters the rich liquid reflux scrubbing tower through the gas phase outlet of the flash reactor. It comes into countercurrent contact with the rich liquid from the absorption tower sprayed in from the top of the tower through the packing layer, which exchanges heat and captures fine droplets.

[0037] The rich liquor reflux has the following functions: 1) Cooling and recovery of cold source. In the rich liquor reflux scrubbing tower, the low-temperature rich liquor and flash steam come into direct countercurrent contact, cooling the flash steam with high efficiency and high recovery efficiency of the cold energy of the low-temperature rich liquor; 2) Droplet capture and reduction of absorbent loss. Due to surface tension, when the rich liquor entering the tower encounters fine droplets, the droplets easily merge on the surface of the droplets formed by the spray; 3) Distillation effect. When the rich liquor enters the rich liquor reflux scrubbing tower, the temperature of the flash steam is higher than that of the rich liquor, and the pressure of the flash steam is lower than the pressure when the rich liquor is saturated (i.e., the rich liquor has reached saturation under normal pressure). As the rich liquor flows downward into the tower, its temperature increases due to direct contact and heat exchange with the flash steam, and the styrene component in the rich liquor continuously volatilizes; as the flash steam enters from the bottom of the tower and flows upward, its temperature decreases and the styrene concentration increases; 4) Improve the efficiency of condenser condensation and recovery of styrene. After the flash steam passes through the rich liquid reflux scrubbing tower, the styrene concentration increases, and the steam temperature decreases significantly, which is beneficial for the condensation and recovery of styrene components after the condenser; 5) A water enrichment layer is formed, improving the flash evaporation effect of styrene. After the rich liquid enters the rich liquid reflux scrubbing tower, a low-temperature zone is formed in the tower relative to the entire flash steam pipeline. Since the partial pressure of water vapor in the flash steam is much higher than that of styrene, and the saturated vapor pressure of water is greatly affected by temperature within the operating temperature range (7.381 kPa at 40℃; 19.932 kPa at 60℃), a large amount of water condenses and enters the rich liquid. The rich liquid enters the flash evaporator through the first-stage flash atomizer 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 scrubbing tower, most of it is condensed again. With this cycle of water, the water vapor concentration in the first-stage flash steam becomes higher and higher, and the reflux rich liquid absorbs more and more water until an equilibrium state of water absorption by the reflux rich liquid is formed. Experiments have shown that adding a certain amount of water to the absorbent solution during distillation of a styrene-absorbing diethyl phthalate solution can significantly improve the distillation effect.

[0038] (4) The flash evaporator is equipped with a multi-layer structure for multi-stage flash evaporation. The flash evaporator is equipped with multi-stage flash chambers and a stripping section at the bottom of the evaporator. This organically combines multi-stage flash evaporation with stripping, improving the rich liquid distillation effect, saving space, improving the vacuuming effect of the vacuum pump, saving the operating cost of the vacuum pump, and making the equipment structure compact and safe.

[0039] The flash evaporation unit has at least two flash chambers, with corresponding connected lean and semi-lean liquid tanks. The rich liquid is first introduced into the upper primary flash chamber and flashed by a primary flash atomizer. The semi-lean liquid after flashing falls into the semi-lean liquid tank through the primary flash guide pipe. It is then extracted, heated by a semi-lean liquid heater, and sent to the lower secondary flash chamber for secondary flashing by a secondary flash atomizer. The lean liquid falls into the lean liquid tank through a secondary flash guide plate. The front end of the secondary flash guide plate is inserted below the liquid surface of the lean liquid tank, forming a liquid seal that separates the secondary flash chamber from the gas lift zone above the semi-lean liquid tank. On one hand, by setting two stages of flash evaporation within a single flash evaporator, the desorption effect is enhanced; on the other hand, the primary and secondary flash chambers are not interconnected, ensuring the optimal flash evaporation effect.

[0040] Aeration heads are installed in the lean and semi-lean liquor tanks. The condensate, from which 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 as water vapor. This allows for air stripping of the lean and semi-lean liquor tanks, truly realizing the reuse of the condensate. The introduction of air stripping gas enhances airflow within the flash evaporation zone. The flow of air stripping gas carries away the styrene gas phase concentrated within the flash evaporation zone, diluting the styrene in the gas phase surrounding the atomized droplets, enhancing the styrene volatilization effect, and improving flash evaporation efficiency.

[0041] (6) Install a liquid-holding column to eliminate cavitation. Considering the cavitation problem at the bottom of the flash reactor, a liquid-holding column is installed to increase the pump pressure for extracting the lean liquid. Since the working pressure of the flash reactor is maintained below 4 kPa (absolute pressure), which is much lower than atmospheric pressure, when the lean liquid is directly pumped from the bottom of the flash reactor into the atmospheric pressure absorption-adsorption unit, the pressure difference before and after the pump is large. The residual styrene components and dissolved water in the lean liquid will cause cavitation, which will affect the stability of pump operation and cause the pump blades to be impacted and corroded. Installing a liquid-holding column and drawing the lean liquid from the bottom of the liquid-holding column into the absorption tower increases the liquid phase pressure at the pump inlet, effectively overcoming the cavitation phenomenon.

[0042] (7) Install a vacuum pump, a flash steam condenser, and an oil-water separator before the pump. Control the negative pressure of the flash chamber, flash steam condenser, and oil-water separator before the pump to be below 4 kPa absolute pressure through the vacuum pump. Install a flash steam condenser upstream of the vacuum pump to cool and condense the flash steam, reduce the volume of flash steam, improve the efficiency of the vacuum pump, and reduce the operating cost of the vacuum pump.

[0043] The flash pressure below 4 kPa was chosen for several reasons: First, it reduces the polymerization of the recovered styrene component. Styrene polymerization accelerates at temperatures up to 60°C, but below 4 kPa, the boiling point of styrene is below 55°C, at which point polymerization is negligible. Second, at an absolute pressure of 4 kPa, the rich liquor temperature only needs to be controlled at around 60°C to achieve a high desorption effect, reducing the temperature resistance requirements on the equipment and its sealing materials, thus lowering equipment investment. Third, the operating pressure of 4 kPa saves on investment and operating costs. Lower operating pressures increase the load on the vacuum pump and place higher demands on the strength and sealing of the vacuum system. Operating pressures above 4 kPa are detrimental to styrene desorption.

[0044] (8) Install an oil-water separator before the pump. Maintain a constant flow of condensate from the oil-water separator to the condensate tank, and increase the oil-water interface level within the separator to allow excess water to be discharged from the condensate. During absorption, some of the water vapor carried by the exhaust gas is absorbed by the absorbent. During flash evaporation, the boiling point of water is lower than that of styrene, so the water preferentially vaporizes and enters the flash steam along with the incoming steam. After condensation, it enters the condensate, disrupting the system's water balance, and excess water needs to be discharged. Maintaining a constant flow of condensate from the oil-water separator to the condensate tank and raising the oil-water interface to a higher position facilitates the discharge of water absorbed by the exhaust gas along with the oil phase, thereby reducing the styrene concentration in the aqueous phase and improving the styrene recovery rate. Because the higher the oil-water interface level, the more thorough the oil phase separation at the aqueous phase outlet, thus reducing the styrene concentration in the circulating steam entering the flash evaporator.

[0045] (9) The condensate tank is connected to the aeration head via a condensate-flue gas vaporizer. The condensate is vaporized and returned to the flash evaporator as stripping gas. Experiments show that when the rich liquid contains a certain amount of water, the styrene desorption rate increases significantly. Since the partial pressure of water vapor in the flash steam is much higher than that of styrene, and the saturated vapor pressure of water is greatly affected by temperature within the operating temperature range (7.381 kPa at 40℃; 19.932 kPa at 60℃), rotary evaporation experiments show that the maximum desorption rate is reached when all the water in the rich liquid is evaporated (i.e., when the aqueous phase disappears). This technical solution continuously aerates the lean and semi-lean liquids with water vapor (approximately 75 kg / h, 3000 m3), resulting in a high gas-liquid ratio of approximately 200-300:1, which is beneficial for further reducing the residual styrene concentration in the lean liquid. Beneficial effects:

[0046] This invention enables ultra-purified discharge of waste gas from artificial stone production lines, while simultaneously recovering VOC components from the waste gas. It features low investment and operating costs, excellent tail gas purification effect, effective coupling of absorption and adsorption, energy saving and consumption reduction, high styrene recovery rate, and environmental friendliness. Using this invention, pollutants in the waste gas of artificial stone production lines are removed at a rate of over 99.9%, and over 98% of the styrene components in the styrene tail gas are recovered. The purified tail gas is discharged ultra-cleanly, with absorbent consumption below 0.1 kg / t-styrene. Compared with distillation processes, it saves over 50% in energy consumption and reduces operating costs by over 50%. Attached Figure Description

[0047] Figure 1 is a system diagram of Embodiment 1 of the present invention.

[0048] Figure 2 is a system diagram of Embodiment 2 of the present invention.

[0049] Figure 3 is a curve showing the fitting of the Henry's constant determined in the experiment according to the present invention.

[0050] Wherein, 1a: main fan; 1b: primary desorption fan; 1c: secondary desorption fan; 1d: incinerator fan; 1e: high-temperature flue gas exhaust fan; 1f: low-temperature flue gas exhaust fan; 3a: primary impeller; 3b: secondary impeller; 4a: primary desorbed gas heat exchanger; 4b: secondary desorbed 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-lean 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 tower; 7 8: Absorber; 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 evaporator; 13-1: Reflux rich liquid atomizer; 13-2: Primary flash atomizer; 13-3: Secondary flash atomizer ; 13-4: Primary flash evaporation guide plate; 13-5: Primary flash evaporation guide pipe; 13-6: Secondary flash evaporation guide plate; 13-7: Air lift guide pipe; 13-8: Secondary flash evaporation guide pipe; 13-9: Primary flash evaporation guide pipe; 13-10: Lean liquor tank; 13-11: Semi-lean liquor tank; 13-12: Lean liquor aerator head; 13-13: Semi-lean liquor aerator head; 14: Liquid holding column; 14-1: Lean liquor overflow pipe; 15: Oil-water separator before pump; 16: Intermediate oil tank; 17: Vacuum unloading valve; 18: Air pump; 19: Incinerator; 20a: Emergency flue gas exhaust valve; 20b: Rich liquor heating flue gas valve; 20c: Flue gas recirculation valve; 20d 20e: Semi-lean liquor heating flue gas valve; 20f: Condensate vaporization flue gas valve; 20g: Purge gas regulating valve; 20h: Primary high-temperature flue gas valve; 20j: Concentrated gas inlet valve; 20k: Concentrated gas inlet valve; 20m: Exhaust flue gas valve; 20n: Rich liquor heating emergency valve; 20p: Primary rotor inlet valve; 20q: Secondary rotor inlet valve; 20r: Primary desorption gas valve; 20s: Secondary desorption gas valve; 20t: Tail gas check valve; 20u: Secondary tower inlet flue gas valve; 20v: Secondary rotor inlet flue gas valve; 20w: Furnace fresh air valve; 20x: Furnace main flue gas valve; 21: Lower explosion limit detector; 22: Filter. Detailed Implementation

[0051] The system of the present invention will be further explained below with reference to the accompanying drawings:

[0052] System Implementation Example 1:

[0053] Referring to Figure 1, the system of the present invention is sequentially connected to a rotary unit, an absorption tower 7, and a flash desorption unit. The rotary unit comprises two stages of rotary turbines connected in series and corresponding desorbed gas heat exchangers. The purified gas outlet of the first-stage rotary turbine 3a is connected to an external discharge pipe via the second-stage rotary turbine 3b. The cooled gas outlet of the first-stage rotary turbine 3a is reconnected to the first-stage rotary turbine 3a via the first-stage desorbed gas heat exchanger 4a; similarly, the cooled gas outlet of the first-stage rotary turbine 3b is reconnected to the first-stage rotary turbine 3a via the first-stage desorbed gas heat exchanger 4b. The specific connection relationships and working principles of the components of the rotary unit are existing technologies and will not be detailed here. The concentrated gas outlet of the first-stage rotary turbine 3a is divided into two paths by the first-stage desorption blower 1b. One path is connected to the gas phase inlet of the absorption tower 7 via the inlet cooler 4d, and the other path is connected to the incinerator 19 (preferably an RTO incinerator). The concentrated gas outlet of the second-stage rotary turbine 3b is connected to the incinerator 19.

[0054] The exhaust gas pipeline is divided into three paths after passing through the main fan 1a. The first and second paths are connected to the desorption gas inlet and tail gas inlet of the rotor unit via the first-stage desorption gas valve 20r and the first-stage rotor inlet valve 20p, respectively. The third path is connected to the inlet of the second-stage rotor 3b via the second-stage rotor inlet valve 20q.

[0055] The absorption tower can be a conventional absorption tower or an absorption tower 7 with an absorption liquid intermediate tank 8 as shown in Figure 1. The absorption tower 7 has at least three spray layers from top to bottom in the middle, and each spray layer corresponds to an independent absorption liquid intermediate tank 8. The upper layer of absorption liquid intermediate tank is connected to the lower layer of absorption liquid intermediate tank through a full flow pipe.

[0056] The gas phase outlet of the absorption tower 7 is connected to the waste gas pipeline via a demister 6.

[0057] The flash evaporation unit includes a flash evaporator 13 and a liquid holding column 14. The flash evaporator 14 has at least two flash chambers and a lower storage tank from top to bottom. In this embodiment, the upper section of the flash evaporator 14 is a primary flash chamber, the lower section is a secondary flash 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 chamber is equipped with a primary flash atomizer 13-2, and the bottom is equipped with a primary flash guide plate 13-4. The upper part of the secondary flash chamber is equipped with a secondary flash atomizer 13-3, and a portion of the lower part of the secondary flash chamber, located above the semi-lean liquid tank, is equipped with a secondary flash guide plate 13-4. 6. The remaining areas are connected to the lean liquid tank 13-10; the front end of the secondary flash evaporation guide plate 13-6 is inserted into the lean liquid tank 13-10; the secondary flash evaporation guide plate 13-6 and the overflow plate separate the semi-lean liquid tank 13-11 from the secondary flash evaporation chamber; the gas phase space above the semi-lean liquid tank 13-11 is connected to the primary flash evaporation chamber via the gas lift guide pipe 13-7, and the primary flash evaporation chamber is connected to the semi-lean liquid tank 13-11 via the primary flash evaporation guide pipe 13-5;

[0058] The rich liquid outlet of the absorption tower 7 is connected to the first-stage flash atomizer 13-2 via a rich liquid intermediate tank 11a, a first-stage flash pump 9d, a lean-rich liquid heat exchanger 4f, a rich liquid-flue gas heat exchanger 4e, and a rich liquid electric auxiliary heater 10a. The semi-lean liquid tank 13-11 is connected to the second-stage flash atomizer 13-3 via a second-stage flash pump 9e, a semi-lean liquid-flue gas heat exchanger 4k, and a semi-lean liquid electric auxiliary heater 10b. The lean liquid tank 13-10 is connected to a liquid holding column 14. The gas phase outlets of the first-stage and second-stage flash chambers are connected to the flash vapor condenser 4h via corresponding first-stage flash demister 12a and second-stage flash demister 12b.

[0059] The condensate outlet of the flash 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 via the pre-pump condensate tank 11b, condensate pump 9j, and condensate-flue gas vaporizer 4j to the lean liquid aerator 13-13 in the lean liquid tank 13-10 and the semi-lean liquid aerator 13-12 in the semi-lean liquid tank 13-11 within the flash evaporator 13. The non-condensable gas outlet of the flash condenser 4h is connected to the exhaust gas pipeline via the exhaust pump 18.

[0060] The lean liquid outlet at the bottom of the liquid holding column 14 is connected to the absorbent inlet of the upper section of the absorption tower 7 via the lean-rich liquid heat exchanger 4e and the lean liquid cooler 4g. The overflow port at the top is connected to the lean liquid tank 13-10 inside the flash evaporator 13 via the lean liquid overflow pipe 14-1.

[0061] The high-temperature flue gas outlet of the incinerator 19 is divided into two paths, which are then merged into one path after passing through the desorber heat exchangers (first-stage desorbed gas heat exchanger 4a and second-stage desorbed gas heat exchanger 4b) corresponding to the two-stage rotors. After passing through the high-temperature flue gas exhaust fan 1e, it is divided into three paths. The first path is connected to the exhaust pipe via the semi-lean liquid-flue gas heat exchanger 4k, the second path is connected to the exhaust pipe via the condensate-flue gas vaporizer 4j, and the third path is divided into two paths via the rich liquid-flue gas heat exchanger 4e. One path is connected to the incinerator 19 via the flue gas circulation valve 20c, and the other path is connected to the exhaust pipe via the exhaust flue gas valve 20m.

[0062] The low-temperature flue gas outlet of the incinerator 19 is divided into two paths via 1f. One path is connected to the rich liquid-flue gas heat exchanger 4e, and the other path is connected to the exhaust pipe via the flue gas exhaust emergency valve 20a.

[0063] Process Example 1:

[0064] Taking a local artificial stone production plant as an example, this plant has four artificial stone production lines. The VOC-generating production units mainly originate from mixing, feeding, material feeding, material distribution, vacuuming, pressing, film removal, and drying. The main pollutants are styrene and non-methane hydrocarbons. During the collection process, the amount of styrene-rich tail gas is 95,000-105,000 Nm³. 3 / h, styrene concentration in exhaust gas in summer is 1500-2000 mg / Nm³3 300-500 mg / Nm³ in winter 3 The enthalpy required by the exhaust gas purification system is provided internally by the system itself.

[0065] Referring to Figure 1, the implementation process is divided into two different operating conditions: summer and winter. The specific operation is as follows:

[0066] Summer: High summer temperatures result in higher styrene concentrations in the exhaust gases from the production line, ranging from 1500-2000 mg / Nm³. 3 .

[0067] 1) Rotary adsorption

[0068] When the secondary rotor inlet valve 20q is closed, the styrene tail gas on the production line is collected and blown into the primary rotor 3a by the main fan 1a through the waste gas pipeline. After being adsorbed by the primary rotor, it enters the secondary rotor 3b for further adsorption and purification before being discharged.

[0069] 2) Desorption

[0070] While the primary rotor 3a and the secondary rotor 3b are adsorbing, the primary desorption gas valve 20r and the secondary desorption gas valve 20s are opened. Under the suction of the primary desorption fan 1b and the secondary desorption fan c, the desorbed gas first cools the rotor. The cooled gas then enters the primary desorption gas heat exchanger 4a and the secondary desorption gas heat exchanger 4b respectively to exchange heat indirectly with the flue gas of about 850°C drawn from the incinerator 19. The temperature of the desorbed gas rises to about 210°C and then enters the rotor for desorption.

[0071] The desorbed gas exiting the first-stage rotor is the first-stage concentrated gas, and the desorbed gas exiting the second-stage rotor is the second-stage concentrated gas.

[0072] The concentration of styrene in the primary concentrated gas is monitored in real time using a lower explosion limit detector 21.

[0073] 3) Absorption of concentrated gas by absorption tower

[0074] Under the suction action of the primary desorption fan 1b, the primary desorption gas (primary concentrated gas, styrene concentration 11000-12000 mg / Nm3) is divided into two parts. One part is introduced into the absorption tower 7, where the styrene component in the concentrated gas is absorbed by the absorbent liquid. According to the system heat balance requirements, a part of the primary desorption gas is separated and mixed with the secondary desorption gas and then incinerated in the incinerator 19 as a measure to balance the system heat enthalpy requirements.

[0075] The concentrated gas enters the tower through the lower inlet of the absorption tower 7 and comes into countercurrent contact with the absorbent liquid (diethyl phthalate absorbent) sprayed down from the top of the tower. Most of the styrene components in the concentrated gas are absorbed.

[0076] The concentrated gas from the absorption tower 7 enters the demister tower 6 to remove mist droplets, then mixes with the non-condensable gas discharged from the suction pump 18, and is introduced into the air inlet of the main fan 1a. After mixing with the exhaust gas from the production line, it enters the rotary unit for adsorption.

[0077] The absorption process is as follows:

[0078] ① The absorbent is sprayed into the tower in three layers. The lean liquid from the flash desorption unit is used as the absorbent and enters the absorbent intermediate tank 8. The absorbent pumped by the first-stage spray pump 9a is mixed and sprayed into the absorbent tower 7. The absorbent comes into countercurrent contact with the concentrated gas through the upper packing layer, and some of the styrene components in the concentrated gas are absorbed. The lean liquid and the fresh absorbent / liquid (diethyl phthalate) are added through the pump head of the first-stage spray pump 9a.

[0079] ② The absorbent liquid flowing through the upper packing layer flows back into the upper layer of the absorbent liquid intermediate tank 8 and is circulated and sprayed by the primary spray pump 9a; an overflow pipe is installed in the upper layer of the absorbent liquid intermediate tank 8, and excess absorbent liquid flows to the lower layer of the absorbent liquid intermediate tank 8 through the overflow pipe.

[0080] ③ The absorbent in the lower layer of the intermediate tank 8 is sprayed into the absorption tower 7 by the secondary spray pump 9b. It comes into countercurrent contact with the concentrated gas through the middle packing layer, and some of the styrene components in the concentrated gas are absorbed.

[0081] ④ The absorbent liquid flowing through the middle packing layer flows into the lower storage tank of the absorption tower 7 and is circulated and sprayed by the secondary spray pump 9b; an overflow pipe is installed in the middle layer of the absorbent liquid intermediate tank 8, and excess absorbent liquid flows to the lower storage tank of the absorption tower 7 through the overflow pipe.

[0082] ⑤ A portion of the absorbent liquid in the lower storage tank of the absorption tower 7 is sprayed into the absorption tower 7 by a three-stage spray pump 9c. The absorbent liquid then comes into countercurrent contact with the concentrated gas through the lower packing layer, and some of the styrene components in the concentrated gas are absorbed.

[0083] ⑥ The absorbent 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 absorbent is sprayed into the absorption tower 7 and comes into countercurrent contact with the concentrated gas through the middle packing layer, and some of the styrene components in the concentrated gas are absorbed.

[0084] ⑦ The rich liquid sent to the flash desorption unit is drawn out through the three-stage spray pump 9c.

[0085] 4) Heat recovery from styrene combustion of concentrated gas

[0086] Under the suction of the secondary desorption fan 1c, the secondary desorbed gas (secondary concentrated gas, styrene concentration 5000-6000 mg / Nm³) is... 3 The flue gas is introduced into the incinerator 19 for combustion, producing high-temperature flue gas at 850℃ and low-temperature flue gas at 110-115℃.

[0087] When the styrene concentration in the exhaust gas from the production line is high, in order to control the styrene concentration in the primary desorbed gas below the lower explosive limit, the flow rate of the primary desorbed gas needs to be increased. This correspondingly increases the enthalpy required for heating the primary desorbed gas. The enthalpy generated by the combustion of the secondary desorbed gas in incinerator 19 alone cannot meet the system's enthalpy requirements; therefore, a portion of the primary desorbed gas (primary concentrated gas, styrene concentration 11000-12000 mg / Nm³) needs to be separated. 3 The primary concentrated gas is mixed with the secondary concentrated gas and then enters the incinerator 19 for combustion and heat extraction. The flow rate of the primary concentrated gas entering the incinerator 19 is regulated by the inlet concentrated gas valve 20j and the inlet concentrated gas valve 20k.

[0088] When the styrene concentration in the exhaust gas from the production line is high, the lower explosion limit detector 21 detects that the styrene concentration in the primary desorbed gas exceeds the set lower limit. The flow rate of the primary desorbed gas is increased by adjusting the primary desorbed gas valve 20r, simultaneously increasing the amount of high-temperature flue gas entering the primary desorbed gas heat exchanger 4a. Due to the increased amount of high-temperature flue gas, the heat generation of the incinerator 19 needs to be increased. This is achieved by adjusting the inlet concentrated gas valve 20k to increase the amount of primary desorbed gas entering the incinerator 19, thus supplementing the system's enthalpy requirements.

[0089] 5) Styrene recovery from rich liquid flash evaporation

[0090] ① 15-20t / h of rich liquor is drawn from the lower storage tank of the absorption tower 7 into the rich liquor intermediate tank 11a, and then pumped out by the first-stage flash pump 9d and successively enters the rich liquor-flue gas heat exchanger 4e and the lean-rich liquor heat exchanger 4f for heat exchange and temperature rise before entering the flash evaporator 13 for the first-stage flash evaporation.

[0091] ② Under the suction action of the vacuum pump, the pressure inside the flash evaporator 13 is controlled at around 4 kPa.

[0092] ③ The rich liquor in the rich liquor intermediate tank 11a is extracted by the first-stage flash pump 9d and first exchanges heat with the lean liquor from the flash desorption unit, and then exchanges heat with the low-temperature flue gas from the incinerator 19 to heat to 60-65℃. Then it is atomized by the first-stage flash atomizer 13-2 and enters the flash evaporator 13. Under negative pressure, 30-40% of the styrene component in the rich liquor volatilizes into the flash steam. The semi-lean liquor with some styrene volatilized flows into the semi-lean liquor tank 13-11 through the first-stage flash guide plate 13-4 and the first-stage flash guide pipe 13-5.

[0093] ④ The semi-lean liquor in the semi-lean liquor tank 13-11 is drawn out by the secondary flash pump 9e and heated to 65-70℃ by the semi-lean liquor-flue gas heat exchanger 4k. Then it is atomized by the secondary flash atomizer 13-3 and enters the flash evaporator 13 for secondary flash evaporation. The styrene component in the semi-lean liquor further volatilizes into the flash steam. The lean liquor with about 20-30% styrene component is introduced into the lean liquor tank 13-12 through the secondary flash guide plate 13-6.

[0094] 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, to further aeration the lean and semi-lean liquids and further reduce the styrene concentration in the lean and semi-lean liquids.

[0095] ⑥ The stripping gas and flash steam are drawn out through stripping gas pipe 13-7, secondary flash steam pipe 13-8 and primary flash steam pipe 13-9 respectively, and after being demisted by stripping demister 12c, secondary flash steam demister 12b and primary flash steam demister 12a respectively, they enter the rich liquid reflux scrubbing tower 5 under the suction action of suction pump 18.

[0096] ⑦ The lean liquor after flash evaporation is drawn from the lean liquor tank 13-10 through the auxiliary discharge pump 9g and enters the holding column 14. Then, it is drawn from the bottom of the holding column 14 through the lean liquor discharge pump 9f and cooled to 20-30℃ through the lean-rich liquor heat exchanger 4f and the lean liquor cooler 4g before entering the absorption tower 7. An overflow pipe 14-1 is installed at the top of the holding column 14 to lead out the excess lean liquor back to the lean liquor tank 13-10 to maintain a stable liquid level in the holding column 14.

[0097] ⑧ The cold rich liquid from the absorption tower 7 is sprayed into the reflux scrubbing tower 5 from the top and comes into countercurrent contact with the flash steam and stripping gas entering from the bottom of the reflux scrubbing tower 5. The rich liquid is heated up, while the flash steam and stripping gas are cooled down. 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 and the flash steam and stripping gas, the fine droplets in the flash steam and stripping gas are captured by the rich liquid. After being heated and the droplets are captured, the rich liquid is atomized by the rich liquid reflux pump for 9 hours and then enters the flash evaporator 13 for flash evaporation.

[0098] ⑨ The flash steam and stripped gas that have entered the flash steam condenser for 4 hours are cooled by a low-temperature refrigerant (7°C low-temperature water). Most of the styrene and water in the steam are condensed and enter the oil-water separator 15 before the pump for oil-water separation. The water phase enters the condensate tank 11b and is then sent by the condensate pump 9j to the condensate-flue gas vaporizer 4j for heating and vaporization to form superheated steam at 60-65°C. The steam bubbled into the semi-lean liquid tank 13-11 and the lean liquid tank 13-10. The oil phase, i.e., styrene, is discharged through the vacuum discharge valve 17 into the intermediate oil tank 16, realizing the recovery of styrene components.

[0099] 6) System heating

[0100] According to the system heat balance analysis, the media that need to be heated are primary desorption gas, secondary desorption gas, rich liquid entering flash evaporator 13, and aeration steam. Among them, primary and secondary desorption gas need to be heated from about 100°C after cooling the rotor to 220°C, rich liquid entering flash evaporator 13 needs to be heated from 20-30°C to 60-65°C, and aeration steam entering flash evaporator 13 needs to be heated from condensate at 20-30°C to 60-65°C.

[0101] ① The secondary desorption gas and part of the primary desorption gas are introduced into the incinerator 19 by the incinerator blower 1d to produce high-temperature flue gas of 850℃ and low-temperature flue gas of 110-115℃.

[0102] ②High-temperature flue gas at 800-850℃ and 5500-6000 Nm is drawn out from the high-temperature flue gas outlet of incinerator 19 via high-temperature flue gas extraction 1e. 3 / h, after being regulated by the first-stage high-temperature flue gas valve 20g and the second-stage high-temperature flue gas valve 20h, it is divided into two parts, which enter the first-stage desorbed gas heat exchanger 4a and the second-stage desorbed gas heat exchanger 4b respectively to exchange heat with the first-stage desorbed gas and the second-stage desorbed gas. The temperature of the desorbed gas rises from 100℃ to 220℃, and the temperature of the high-temperature flue gas drops to 210-250℃.

[0103] ③ The high-temperature flue gas, cooled to 210-250℃, is extracted by the high-temperature flue gas exhaust fan 1e. It then passes through the semi-lean liquid heating flue gas valve 20d, the condensate vaporization flue gas valve 20e, and the rich liquid heating emergency valve 20n, and is divided into three parts. One part enters the semi-lean liquid-flue gas heat exchanger 4k to heat the semi-lean liquid, another part enters the condensate-flue gas vaporizer 4j, and the remaining part is introduced into the internal circulation of the incinerator 19 through the incinerator fan 1d to dilute the concentrated gas entering the furnace.

[0104] ④ Low-temperature flue gas at 105-115℃ and 13000-14000 Nm is drawn out from the low-temperature flue gas port of incinerator 19 via low-temperature flue gas extraction 1f. 3 / h, the flue gas is divided into two parts by the rich liquid heating flue gas valve 20b and the flue gas exhaust emergency valve 20a. One part enters the rich liquid-flue gas heat exchanger 4e to exchange heat with the rich liquid, and the temperature of the low-temperature flue gas drops from 105-115℃ to 60-70℃; the remaining part is discharged from the chimney by the flue gas exhaust emergency valve 20a.

[0105] ⑤ The low-temperature flue gas, which exits the rich liquid-flue gas heat exchanger 4e and whose temperature drops to 60-70℃, enters the incinerator 19 through the flue gas circulation valve 20c and the exhaust flue gas valve 20m, and the circulating flue gas volume and the exhaust flue gas volume are regulated.

[0106] ⑥ The amount of flue gas emitted from the chimney is minimized by adjusting the emergency exhaust valve 20a. The amount of primary desorption gas introduced into the incinerator 19 is adjusted based on the amount of low-temperature flue gas discharged through the emergency exhaust valve 20a. When the amount of low-temperature flue gas discharged through the emergency exhaust valve 20a is excessive, the amount of primary desorption gas introduced into the incinerator 19 is reduced until it is no longer discharged through the emergency exhaust valve 20a, thereby increasing the amount of primary desorption gas entering the absorption tower 7 and improving the absorption capacity of styrene.

[0107] 7) Non-condensable gas recovery and treatment

[0108] The pressure inside the flash evaporator was controlled at 4 kPa, and the gas volume discharged by the vacuum pump was approximately 4000 m³. 3 / h, of which non-condensable gases comprise 10-20% (based on 60m³). 3 (Based on / h), after being cooled to approximately 20°C in a flash condenser for 4 hours, the moisture and most of the styrene components in the flash steam condense and exit the pump, entering a state of atmospheric pressure. The volume of non-condensable gas is 2.11 m³. 3 The remaining non-condensable gas has a high styrene concentration, approximately 29 g / Nm³. 3 The amount of styrene carried out by non-condensable gas is approximately 60 g / h.

[0109] If the styrene concentration in the non-condensable gas exceeds the lower explosive limit of styrene, it should be promptly mixed and diluted with the concentrated gas after it exits the absorption tower 7 and passes through the demister tower 6 to remove droplets. The mixture is then introduced into the inlet of the main blower 1a and mixed with the exhaust gas from the production line before entering the rotary adsorption to recover the styrene components.

[0110] Winter: Due to low winter temperatures, the concentration of styrene in the exhaust gas from the production line is relatively low, at 300-500 mg / Nm³. 3 .

[0111] During winter operation, only the secondary rotor 3b is turned on and the primary rotor 3a is turned off. That is, the primary rotor inlet valve 20p is closed and the secondary rotor inlet valve 20q is turned on. The styrene tail gas on the production line is collected and blown into the secondary rotor 3b for adsorption and purification by the main blower 1a before being discharged. At the same time, the absorption and flash evaporation desorption units are turned off. The rest of the operation process is the same as above.

[0112] System Implementation Example 2:

[0113] Referring to Figure 2, the system of the present invention is sequentially connected to the rotary wheel unit, the absorption tower 7, and the flash desorption unit;

[0114] The impeller unit comprises two impellers connected in series and corresponding desorbed gas heat exchangers. The purified gas outlet of the first-stage impeller 3a is connected to the exhaust pipe via the second-stage impeller 3b. The cooled gas outlet of the first-stage impeller 3a is connected back to the first-stage impeller 3a via the first-stage desorbed gas heat exchanger 4a. Similarly, the cooled gas outlet of the first-stage impeller 3b is connected back to the first-stage impeller 3a via the first-stage desorbed gas heat exchanger 4b. The specific connection relationships and working principles of the components of the impeller unit are existing technologies and will not be detailed here. The concentrated gas outlet of the first-stage impeller 3a (equipped 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 inlet concentrated gas valve 20j, the inlet and outlet gas heat exchanger 4c, and the inlet cooler 4d. The concentrated gas outlet of the second-stage impeller 3b is divided into two paths: one path is connected to the inlet and outlet gas heat exchanger 4c via the second-stage inlet flue gas valve 20u, and the other path is connected to the waste gas pipe via the second-stage impeller flue gas valve 20v.

[0115] The exhaust gas pipeline is divided into three paths after passing through the main fan 1a. The first and second paths are connected to the desorption gas inlet and tail gas inlet of the rotor unit via the first-stage desorption gas valve 20r and the first-stage rotor inlet valve 20p, respectively. The third path is connected to the inlet of the second-stage rotor 3b via the second-stage rotor inlet valve 20q.

[0116] The absorption tower can be a conventional absorption tower or an absorption tower 7 with an absorption liquid intermediate tank 8 as shown in Figure 1. The absorption tower 7 has at least three spray layers from top to bottom in the middle, and each spray layer corresponds to an independent absorption liquid intermediate tank 8. The upper layer of absorption liquid intermediate tank is connected to the lower layer of absorption liquid intermediate tank through a full flow pipe.

[0117] The gas phase outlet of the absorption tower 7 is connected to the incinerator 19 via the demister 6 and the inlet / outlet gas heat exchanger 4c.

[0118] The flash evaporation unit includes a flash evaporator 13 and a liquid holding column 14. The flash evaporator 14 has at least two flash chambers and a lower storage tank from top to bottom. In this embodiment, the upper section of the flash evaporator 14 is a primary flash chamber, the lower section is a secondary flash 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 chamber is equipped with a reflux rich liquid atomizer 13-1 and a primary flash evaporation atomizer 13-2, and the bottom is a primary flash evaporation guide plate 13-4. The upper part of the secondary flash chamber is equipped with a secondary flash evaporation atomizer 13-3, and a portion of the lower part of the secondary flash chamber is located above the semi-lean liquid tank and is equipped with a secondary flash evaporation atomizer. The guide plate 13-6, with the remaining area connected to the lean liquid tank 13-10; the front end of the secondary flash evaporation guide plate 13-6 is inserted into the lean liquid tank 13-10; the secondary flash evaporation guide plate 13-6 and the overflow plate separate the semi-lean liquid tank 13-11 from the secondary flash evaporation chamber; the gas phase space above the semi-lean liquid tank 13-11 is connected to the primary flash evaporation chamber via the gas lift gas guide pipe 13-7, and the primary flash evaporation chamber is connected to the semi-lean liquid tank 13-11 via the primary flash evaporation guide pipe 13-5;

[0119] The rich liquid outlet of the absorption tower 7 is divided into two paths. One path connects 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 path connects to the reflux rich liquid atomizer 13-1 of the flash reactor 13 via the rich liquid reflux tower 5 and the rich liquid reflux pump 9h. The semi-lean liquid tank 13-11 connects 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 vapor condenser 4h in sequence via the corresponding first-stage flash demister 12a and second-stage flash demister 12b.

[0120] The condensate outlet of the flash 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 via the pre-pump condensate tank 11b, condensate pump 9j, and condensate-flue gas vaporizer 4j to the lean liquid aerator 13-13 in the lean liquid tank 13-10 and the semi-lean liquid aerator 13-12 in the semi-lean liquid tank 13-11 within the flash reactor 13. The non-condensable gas outlet of the flash condenser 4h is connected to the incinerator 19 via the inlet / outlet gas heat exchanger 4c.

[0121] The lean liquid outlet at the bottom of the liquid holding column 14 is connected to the absorbent inlet of the upper section of the absorption tower 7 via the lean-rich liquid heat exchanger 4e and the lean liquid cooler 4g. The overflow port at the top is connected to the lean liquid tank 13-10 inside the flash evaporator 13 via the lean liquid overflow pipe 14-1.

[0122] The high-temperature flue gas outlet of the incinerator 19 is divided into two paths, which are then merged into one path after passing through the desorber heat exchangers (first-stage desorbed gas heat exchanger 4a and second-stage desorbed gas heat exchanger 4b) corresponding to the two-stage rotors. After passing through the high-temperature flue gas exhaust fan 1e, it is divided into three paths. The first path is connected to the exhaust pipe via the semi-lean liquid-flue gas heat exchanger 4k, the second path is connected to the exhaust pipe via the condensate-flue gas vaporizer 4j, and the third path is divided into two paths via the rich liquid-flue gas heat exchanger 4e. One path is connected to the incinerator 19 via the flue gas circulation valve 20c, and the other path is connected to the exhaust pipe via the exhaust flue gas valve 20m.

[0123] The low-temperature flue gas outlet of the incinerator 19 is divided into two paths via 1f. One path is connected to the rich liquid-flue gas heat exchanger 4e, and the other path is connected to the exhaust pipe via the flue gas exhaust emergency valve 20a.

[0124] Process Example 2:

[0125] Referring to Figure 2, the implementation process is divided into two different operating conditions: summer and winter. The specific operations are as follows:

[0126] Summer: High summer temperatures result in higher styrene concentrations in the exhaust gases from the production line, ranging from 1500-2000 mg / Nm³. 3 .

[0127] 1) Rotary adsorption

[0128] When the secondary rotor inlet valve 20q is closed, the styrene tail gas on the production line is collected and blown into the primary rotor 3a by the main fan 1a through the waste gas pipeline. After being adsorbed by the primary rotor, it enters the secondary rotor 3b for further adsorption and purification before being discharged.

[0129] 2) Desorption

[0130] While the primary rotor 3a and secondary rotor 3b are adsorbing, the primary desorption gas valve 20r and the secondary desorption gas valve 20s are opened. Under the suction of the primary desorption fan 1b and the secondary desorption fan c, the desorbed gas first cools the rotors. The cooled gas then enters the primary desorption gas heat exchanger 4a and the secondary desorption gas heat exchanger 4b respectively, where it indirectly exchanges heat with the flue gas at approximately 850°C drawn from the incinerator 19. The temperature of the desorbed gas rises to approximately 210°C before it enters the rotors for desorption. The desorbed gas exiting the primary rotor 3a, i.e., the primary concentrated gas, enters the absorption tower 7.

[0131] The styrene concentration in the primary enriched gas is monitored in real time using a lower explosion limit detector 21 to control the styrene concentration in the primary enriched gas within 11-12 g / Nm³. 3 between.

[0132] The secondary concentrated gas exiting the secondary rotor 3b is divided into two parts. These parts are regulated via the secondary tower inlet flue gas valve 20u and the secondary rotor inlet flue gas valve 20v based on the styrene concentration in the primary concentrated gas monitored by the lower explosion limit detector 21. The secondary rotor inlet flue gas valve 20v remains normally open. When the concentration exceeds 12 g / Nm³... 3 When the temperature drops below 11 g / Nm³, open the secondary flue gas inlet valve 20 u and replenish with secondary concentrated gas for dilution. 3 At that time, close the secondary flue gas inlet valve 20u.

[0133] 3) Absorption of concentrated gas by absorption tower

[0134] Under the suction of the primary desorption fan 1b, the styrene concentration is 11000-12000 mg / Nm³. 3 The primary concentrated gas and part of the secondary concentrated gas are introduced into the absorption tower 7.

[0135] The concentrated gas enters the tower through the lower inlet of the absorption tower 7 and comes into countercurrent contact with the absorbent liquid (diethyl phthalate absorbent) sprayed down from the top of the tower. Most of the styrene components in the concentrated gas are absorbed.

[0136] The concentrated gas from the absorption tower 7 enters the demister tower 6 to remove mist droplets, and then mixes with the non-condensable gas discharged from the suction pump 18 before entering the incinerator 19 for incineration and heat extraction.

[0137] The absorption process is as follows:

[0138] ① The absorbent is sprayed into the tower in three layers. The absorbent from the flash desorption unit is mixed with the absorbent drawn from the upper layer of the absorbent intermediate tank 8 by the first-stage spray pump 9a and sprayed into the absorbent tower 7. The absorbent comes into countercurrent contact with the concentrated gas through the upper packing layer, and some of the styrene components in the concentrated gas are absorbed. The lean liquid and the fresh absorbent / liquid (diethyl phthalate) are added through the pump head of the first-stage spray pump 9a.

[0139] ② The absorbent liquid flowing through the upper packing layer flows back into the upper layer of the absorbent liquid intermediate tank 8 and is circulated and sprayed by the primary spray pump 9a; an overflow pipe is installed in the upper layer of the absorbent liquid intermediate tank 8, and excess absorbent liquid flows to the lower layer of the absorbent liquid intermediate tank 8 through the overflow pipe.

[0140] ③ The absorbent in the lower layer of the intermediate tank 8 is sprayed into the absorption tower 7 by the secondary spray pump 9b. It comes into countercurrent contact with the concentrated gas through the middle packing layer, and some of the styrene components in the concentrated gas are absorbed.

[0141] ④ The absorbent liquid flowing through the middle packing layer flows into the lower storage tank of the absorption tower 7 and is circulated and sprayed by the secondary spray pump 9b; an overflow pipe is installed in the middle layer of the absorbent liquid intermediate tank 8, and excess absorbent liquid flows to the lower storage tank of the absorption tower 7 through the overflow pipe.

[0142] ⑤ A portion of the absorbent liquid in the lower storage tank of the absorption tower 7 is sprayed into the absorption tower 7 by a three-stage spray pump 9c. The absorbent liquid then comes into countercurrent contact with the concentrated gas through the lower packing layer, and some of the styrene components in the concentrated gas are absorbed.

[0143] ⑥ The absorbent 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 absorbent is sprayed into the absorption tower 7 and comes into countercurrent contact with the concentrated gas through the middle packing layer, and some of the styrene components in the concentrated gas are absorbed.

[0144] ⑦ The rich liquid sent to the flash desorption unit is drawn out through the three-stage spray pump 9c.

[0145] 4) Heat recovery from the concentrated gas exiting the absorption tower by combustion.

[0146] The concentrated gas exiting the absorption tower 7 and being demisted by the demister 6 is introduced into the incinerator 19 for combustion, producing high-temperature flue gas at 850°C and low-temperature flue gas at 110-115°C, which are used for heat extraction by the system.

[0147] The styrene concentration in the concentrated gas exiting absorber 7 and after demistering 6 is adjusted according to the required enthalpy of the system and controlled between 4000-6000 mg / Nm³.3 between.

[0148] When the system's enthalpy demand increases, the frequency of the first-stage spray pump 9a is reduced, the first-stage spray volume is decreased, and the styrene concentration in the concentrated gas exiting the tower is increased, thereby increasing the heat output of the incinerator 19. Conversely, when the system's enthalpy demand increases, the frequency of the first-stage spray pump 9a is reduced, the first-stage spray volume is increased, and the styrene concentration in the concentrated gas exiting the tower is decreased, thereby reducing the heat output of the incinerator 19.

[0149] If the styrene concentration in the non-condensable gas exceeds the lower explosive limit of styrene concentration, it should be mixed with the concentrated gas exiting the tower in time and then entered the incinerator 19 for incineration and heat extraction.

[0150] 5) Styrene recovery from rich liquid flash evaporation

[0151] ① 15-20 t / h of rich liquid is drawn from the storage tank at the bottom of the absorption tower 7 into the flash evaporation and desorption unit. 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. Then, it is pumped out by the first-stage flash pump 9d and successively enters the rich liquid-flue gas heat exchanger 4e and the lean-rich liquid heat exchanger 4f for heat exchange and temperature rise before entering the flash evaporator 13 for the first-stage flash evaporation.

[0152] ② Under the suction action of the vacuum pump, the pressure inside the flash evaporator 13 is controlled at around 4 kPa.

[0153] ③ The rich liquor in the rich liquor intermediate tank 11a is extracted by the first-stage flash pump 9d and first exchanges heat with the lean liquor from the flash desorption unit, and then exchanges heat with the low-temperature flue gas from the incinerator 19 to heat to 60-65℃. Then it is atomized by the first-stage flash atomizer 13-2 and enters the flash evaporator 13. Under negative pressure, 30-40% of the styrene component in the rich liquor volatilizes into the flash steam. The semi-lean liquor with some styrene volatilized flows into the semi-lean liquor tank 13-11 through the first-stage flash guide plate 13-4 and the first-stage flash guide pipe 13-5.

[0154] ④ The semi-lean liquor in the semi-lean liquor tank 13-11 is drawn out by the secondary flash pump 9e and heated to 65-70℃ by the semi-lean liquor-flue gas heat exchanger 4k. Then it is atomized by the secondary flash atomizer 13-3 and enters the flash evaporator 13 for secondary flash evaporation. The styrene component in the semi-lean liquor further volatilizes into the flash steam. The lean liquor with about 20-30% styrene component is introduced into the lean liquor tank 13-12 through the secondary flash guide plate 13-6.

[0155] 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, to further aeration the lean and semi-lean liquids and further reduce the styrene concentration in the lean and semi-lean liquids.

[0156] ⑥ The stripping gas and flash steam are drawn out through stripping gas pipe 13-7, secondary flash steam pipe 13-8 and primary flash steam pipe 13-9 respectively, and then demisted by stripping demister 12c, secondary flash steam demister 12b and primary flash steam demister 12a respectively. Under the suction of pump 18, they enter the rich liquid reflux scrubbing tower 5.

[0157] ⑦ The lean liquor after flash evaporation is drawn from the lean liquor tank 13-10 through the auxiliary discharge pump 9g and enters the holding column 14. Then, it is drawn from the bottom of the holding column 14 through the lean liquor discharge pump 9f and cooled to 20-30℃ through the lean-rich liquor heat exchanger 4f and the lean liquor cooler 4g before entering the absorption tower 7. An overflow pipe 14-1 is installed at the top of the holding column 14 to lead out the excess lean liquor back to the lean liquor tank 13-10 to maintain a stable liquid level in the holding column 14.

[0158] ⑧ The cold rich liquid from the absorption tower 7 is sprayed into the reflux scrubbing tower 5 from the top and comes into countercurrent contact with the flash steam and stripping gas entering from the bottom of the reflux scrubbing tower 5. The rich liquid is heated up, while the flash steam and stripping gas are cooled down. 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 and the flash steam and stripping gas, the fine droplets in the flash steam and stripping gas are captured by the rich liquid. After being heated and the droplets are captured, the rich liquid is atomized by the rich liquid reflux pump for 9 hours and then enters the flash evaporator 13 for flash evaporation.

[0159] ⑨ The flash steam and stripped gas that have entered the flash steam condenser for 4 hours are cooled by a low-temperature refrigerant (7°C low-temperature water). Most of the styrene and water in the steam are condensed and enter the oil-water separator 15 before the pump for oil-water separation. The water phase enters the condensate tank 11b and is then sent by the condensate pump 9j to the condensate-flue gas vaporizer 4j for heating and vaporization to form superheated steam at 60-65°C. The steam bubbled into the semi-lean liquid tank 13-11 and the lean liquid tank 13-10. The oil phase, i.e., styrene, is discharged through the vacuum discharge valve 17 into the intermediate oil tank 16, realizing the recovery of styrene components.

[0160] 6) System heating

[0161] According to the system heat balance analysis, the media that need to be heated are primary desorption gas, secondary desorption gas, rich liquid entering flash evaporator 13, and aeration steam. Among them, primary and secondary desorption gas need to be heated from about 100°C after cooling the rotor to 220°C, rich liquid entering flash evaporator 13 needs to be heated from 20-30°C to 60-65°C, and aeration steam entering flash evaporator 13 needs to be heated from condensate at 20-30°C to 60-65°C.

[0162] ① The secondary desorption gas and part of the primary desorption gas are introduced into the incinerator 19 by the incinerator blower 1d to produce high-temperature flue gas of 850℃ and low-temperature flue gas of 110-115℃.

[0163] ②High-temperature flue gas at 800-850℃ and 5500-6000 Nm is drawn out from the high-temperature flue gas outlet of incinerator 19 via high-temperature flue gas extraction 1e. 3 / h, after being regulated by the first-stage high-temperature flue gas valve 20g and the second-stage high-temperature flue gas valve 20h, it is divided into two parts, which enter the first-stage desorbed gas heat exchanger 4a and the second-stage desorbed gas heat exchanger 4b respectively to exchange heat with the first-stage desorbed gas and the second-stage desorbed gas. The temperature of the desorbed gas rises from 100℃ to 220℃, and the temperature of the high-temperature flue gas drops to 210-250℃.

[0164] ③ The high-temperature flue gas, cooled to 210-250℃, is extracted by the high-temperature flue gas exhaust fan 1e. It then passes through the semi-lean liquid heating flue gas valve 20d, the condensate vaporization flue gas valve 20e, and the rich liquid heating emergency valve 20n, and is divided into three parts. One part enters the semi-lean liquid-flue gas heat exchanger 4k to heat the semi-lean liquid, another part enters the condensate-flue gas vaporizer 4j, and the remaining part is introduced into the internal circulation of the incinerator 19 through the incinerator fan 1d to dilute the concentrated gas entering the furnace.

[0165] ④ Low-temperature flue gas at 105-115℃ and 13000-14000 Nm is drawn out from the low-temperature flue gas port of incinerator 19 via low-temperature flue gas extraction 1f. 3 / h, the flue gas is divided into two parts by the rich liquid heating flue gas valve 20b and the flue gas exhaust emergency valve 20a. One part enters the rich liquid-flue gas heat exchanger 4e to exchange heat with the rich liquid, and the temperature of the low-temperature flue gas drops from 105-115℃ to 60-70℃; the remaining part is discharged from the chimney by the flue gas exhaust emergency valve 20a.

[0166] ⑤ The low-temperature flue gas, which exits the rich liquid-flue gas heat exchanger 4e and whose temperature drops to 60-70℃, enters the incinerator 19 through the flue gas circulation valve 20c and the exhaust flue gas valve 20m, and the circulating flue gas volume and the exhaust flue gas volume are regulated.

[0167] ⑥ The amount of flue gas emitted from the chimney is minimized by adjusting the emergency exhaust valve 20a. The amount of primary desorption gas introduced into the incinerator 19 is adjusted based on the amount of low-temperature flue gas discharged through the emergency exhaust valve 20a. When the amount of low-temperature flue gas discharged through the emergency exhaust valve 20a is excessive, the amount of primary desorption gas introduced into the incinerator 19 is reduced until it is no longer discharged through the emergency exhaust valve 20a, thereby increasing the amount of primary desorption gas entering the absorption tower 7 and improving the absorption capacity of styrene.

[0168] 7) Non-condensable gas recovery and treatment

[0169] The pressure inside the flash evaporator was controlled at 4 kPa, and the gas volume discharged by the vacuum pump was approximately 4000 m³. 3 / h, of which non-condensable gases comprise 10-20% (based on 60m³). 3(Based on / h), after being cooled to approximately 20°C in a flash condenser for 4 hours, the moisture and most of the styrene components in the flash steam condense and exit the pump, entering a state of atmospheric pressure. The volume of non-condensable gas is 2.11 m³. 3 The remaining non-condensable gas has a high styrene concentration, approximately 29 g / Nm³. 3 The amount of styrene carried out by non-condensable gas is approximately 60 g / h.

[0170] If the styrene concentration in the non-condensable gas exceeds the lower explosive limit of styrene concentration, it should be mixed with the concentrated gas exiting the tower in time and then entered the incinerator 19 for incineration and heat extraction.

[0171] 8) Diethyl phthalate is preferred as the styrene absorbent.

[0172] The absorbent used in the method of the present invention is a high-boiling-point organic solvent with a boiling point more than 100°C higher than that of styrene, preferably diethyl phthalate.

[0173] Referring to Figure 3, the Henry's constant of the solution after diethyl phthalate absorbs styrene is 23.04 kg / (mol·kPa).

[0174] The process of this invention 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 0.1 kg / t-styrene absorbent. Compared with the distillation process, it saves more than 50% of energy consumption and reduces the recovery cost by more than 50%.

[0175] Winter: Due to low winter temperatures, the concentration of styrene in the exhaust gas from the production line is relatively low, at 300-500 mg / Nm³. 3 .

[0176] During winter operation, only the secondary rotor 3b is turned on and the primary rotor 3a is turned off. That is, the primary rotor inlet valve 20p is closed and the secondary rotor inlet valve 20q is turned on. The styrene tail gas on the production line is collected and blown into the secondary rotor 3b for adsorption and purification by the main blower 1a before being discharged. At the same time, the absorption and flash evaporation desorption units are turned off. The rest of the operation process is the same as above.

Claims

1. A styrene recovery system for waste gas from an artificial stone production line based on adsorption, concentration, and coupling absorption, characterized in that, The system includes a rotor unit, an absorption tower, and a flash desorption unit connected in sequence. A waste gas pipeline connects to the tail gas inlet of the rotor unit, and the concentrated gas outlet of the rotor unit connects to the gas phase inlet at the bottom of the absorption tower. The gas phase outlet of the absorption tower is connected to an incinerator or the waste gas pipeline via a demister. The rich liquid outlet of the absorption tower is connected to the flash desorption unit, and the lean liquid outlet of the flash desorption unit is connected to the absorbent inlet at the top of the absorption tower via a liquid-holding column.

2. The styrene recovery system for waste gas from an artificial stone production line based on adsorption, concentration, and coupling absorption as described in claim 1, characterized in that, The rotor unit includes two-stage rotors connected in series and corresponding desorbed gas heat exchangers. The purified gas outlet of the first-stage rotor is connected to the 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 a first-stage desorption fan and an inlet cooler. The concentrated gas outlet of the second-stage rotor is connected to the incinerator or split into two paths, one connected to the waste gas pipeline and the other connected to the inlet cooler.

3. The styrene recovery system for waste gas from an artificial stone production line based on adsorption, concentration, and coupling absorption as described in claim 2, characterized in that, The outlet of the primary desorption fan is divided into two paths: one path connects to the tower cooler, and the other path connects to the incinerator.

4. The styrene recovery system for waste gas from an artificial stone production line based on adsorption, concentration, and coupling absorption as described in any one of claims 1-3, characterized in that, The flash evaporation unit includes a flash evaporator, which has at least two flash chambers and a bottom liquid storage tank from top to bottom.

5. The styrene recovery system for waste gas from an artificial stone production line based on adsorption concentration coupling absorption as described in claim 4, characterized in that, The upper section of the flash evaporator 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 equipped with a primary flash atomizer, and the bottom is equipped with a primary flash guide plate. The upper part of the secondary flash chamber is equipped with a secondary flash atomizer, and a portion of the lower part of the secondary flash chamber, located above the semi-lean liquid tank, is equipped with a secondary flash guide plate, while 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 lift gas guide pipe, and the primary flash chamber is connected to the semi-lean liquid tank via a primary flash guide pipe. The rich liquid outlet of the absorption tower is connected to the first-stage flash atomizer 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; the semi-lean liquid tank is connected to the second-stage flash atomizer via a semi-lean liquid-flue gas heat exchanger and a semi-lean liquid electric auxiliary heater; and the lean liquid tank is connected to a liquid holding column.

6. The styrene recovery system for waste gas from an artificial stone production line based on adsorption, concentration, and coupling absorption as described in claim 5, characterized in that, The flash evaporation analysis unit includes a flash evaporator and a rich liquid reflux scrubbing tower. The upper section of the first-stage flash chamber of the flash evaporator is also equipped with a rich liquid reflux atomizer. The rich liquid outlet of the absorption tower is divided into two paths. One path is connected to the first-stage flash evaporation atomizer 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. The other path is connected to the scrubbing liquid inlet of the rich liquid reflux scrubbing tower. The rich liquid outlet at the bottom of the rich liquid reflux scrubbing tower is divided into two paths: one path connects to the rich liquid atomizer of the flash evaporator, and the other path connects to the rich liquid intermediate tank. The gas phase outlet of the flash evaporator is connected to a flash condenser via a rich liquid reflux scrubbing tower.

7. The styrene recovery system for waste gas from an artificial stone production line based on adsorption, concentration, and coupling absorption as described in claim 6, characterized in that, The lean liquid outlet at the bottom of the liquid-holding column is connected to the absorbent inlet of the absorption tower via a lean-rich liquid heat exchanger, and the overflow port at the top is connected to the lean liquid tank inside the flash evaporator via a lean liquid overflow pipe.

8. The styrene recovery system for waste gas from an artificial stone production line based on adsorption concentration coupling absorption as described in any one of claims 5-7, characterized in that, Both the lean liquid tank and the semi-lean liquid tank inside the flash evaporator are equipped with aeration heads.

9. The styrene recovery system for waste gas from an artificial stone production line based on adsorption, concentration, and coupling absorption as described in claim 8, characterized in that, The gas phase outlets of both the primary and secondary flash chambers are connected to a flash vapor condenser or a rich liquid reflux scrubbing tower via corresponding demisters.

10. The styrene recovery system for waste gas from an artificial stone production line based on adsorption, concentration, and coupling absorption as described in claim 8, characterized in that, The condensate outlet of the flash condenser is connected to the oil-water separator before the pump. The condensate outlet of the oil-water separator before the pump is connected to the aeration heads in the lean liquid tank and semi-lean liquid tank inside the flash reactor via the condensate tank before the exhaust pump, the condensate pump, and the condensate-flue gas vaporizer. The non-condensable gas outlet of the flash condenser is connected to the incinerator or waste gas pipeline via the exhaust pump.

11. The styrene recovery system for waste gas from an artificial stone production line based on adsorption concentration coupling absorption as described in any one of claims 1-3, characterized in that, The high-temperature flue gas outlet of the incinerator is connected to the desorbed gas heat exchanger of the rotary unit. The flue gas outlet of the desorbed gas heat exchanger is divided into three paths after passing through the high-temperature flue gas exhaust fan. The first path is connected to the exhaust pipe via the semi-lean liquid-flue gas heat exchanger. The second path is connected to the exhaust pipe via the condensate-flue gas vaporizer. The third path is further divided into two paths via the rich liquid-flue gas heat exchanger. One path is connected to the incinerator via the flue gas recirculation valve, and the other path is connected to the exhaust pipe.

12. The styrene recovery system for artificial stone production line waste gas based on adsorption concentration coupling absorption as described in claim 11, characterized in that, The rotor unit includes two-stage rotors connected in series and corresponding desorber heat exchangers. The high-temperature flue gas outlet of the incinerator is divided into two paths, which are merged into one path after passing through the desorber heat exchangers corresponding to the two-stage rotors, and then divided into three paths after passing through the high-temperature flue gas exhaust fan. The low-temperature flue gas outlet of the incinerator is also connected to a rich liquid-flue gas heat exchanger.

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