Resource recycling method for styrene pollution component in waste gas of artificial stone production line

Abstract

The invention discloses an artificial stone production line waste gas styrene pollution component resource recovery method which comprises the following steps: artificial stone production line waste gas enters a rotating wheel unit under the suction action of a fan for adsorption and concentration, purified tail gas after adsorption is discharged, and desorbed concentrated gas enters an absorption tower to be in countercurrent contact with an absorbent barren solution in the tower; a styrene component is absorbed, and concentrated gas at the top of the tower is demisted by a demisting tower and then is led out, or is fed into an incinerator, or is mixed with waste gas of an artificial stone production line and then is fed into a rotating wheel unit; a rich solution absorbing the styrene component at the bottom of the absorption tower is heated and then fed into a flash evaporation analysis unit, the styrene component is analyzed and recycled, and a barren solution obtained after analysis returns to the absorption tower to serve as an absorbent to circularly spray and absorb styrene. The method has the advantages of simple process, effective coupling of absorption and runner adsorption, low investment and operation cost, good tail gas purification effect, energy saving, consumption reduction and high styrene recovery rate.

Description

Technical Field

[0001] The present invention belongs to the field of VOC tail gas treatment, and relates to a resource recovery and utilization of polluting components in VOC tail gas, and specifically to a resource recovery method for styrene polluting components in waste gas of an artificial stone production line. Background Art

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

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

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

[0005] The absorption method can realize the resource recovery of pollutant components in tail gas. Since the absorption process mainly uses organic solvents, the absorption driving force is small, the purification effect is poor, the tail gas after purification is difficult to meet the standards, the absorption capacity of the absorbent is small, and the regeneration cost of the absorbent is high.

[0006] Adsorption is one of the common treatment measures for VOC tail gas, which can achieve standard emission. However, for high-concentration and high-volume tail gas, the adsorption cycle is short, there are frequent adsorption and desorption, high operating energy consumption, and the saturated adsorbent is hazardous waste, the adsorbent consumption is large, and the disposal cost is high.

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

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

[0009] The purpose of the present invention is to solve the above technical problems and to provide a method for resource recovery of styrene pollution components in waste gas from an artificial stone production line, which has simple process, effective coupling of absorption and rotor adsorption, low investment and operating costs, good tail gas purification effect, energy saving and consumption reduction, and high styrene recovery rate.

[0010] The invention discloses a method for recycling styrene pollution components in waste gas from an artificial stone production line. The waste gas from the artificial stone production line enters a rotary unit for adsorption and concentration under the suction action of a fan, and the purified tail gas after adsorption is discharged. The concentrated gas after desorption enters an absorption tower and countercurrently contacts with the absorbent lean liquid in the tower, and the styrene component is absorbed. The concentrated gas at the top of the tower is defogged by a defogger and then led out, or sent to an incinerator, or mixed with the waste gas from the artificial stone production line and then sent to the rotary unit. The rich liquid at the bottom of the absorption tower that absorbs the styrene component is heated and sent to a flash evaporation analysis unit, and the styrene component is analyzed and recovered. The lean liquid after analysis returns to the absorption tower as an absorbent for cyclic spraying to absorb styrene.

[0011] The rotor unit comprises two stages of rotors connected in series, wherein the primary purified gas generated after adsorption by the primary rotor is further adsorbed by the secondary rotor to obtain purified tail gas for external discharge; the primary concentrated gas generated by the primary rotor is cooled to below 25°C and sent to the absorption tower for countercurrent contact with the absorbent lean liquid in the tower; the secondary concentrated gas generated by the secondary rotor is either sent to the incinerator, or part of it is mixed with the exhaust gas from the artificial stone production line and then sent to the primary rotor, and the rest is mixed with the primary concentrated gas and then sent to the absorption tower.

[0012] The primary concentrated gas generated after the primary wheel adsorption is divided into two streams, one stream is sent to the absorption tower, and the other stream is sent to the incinerator.

[0013] The flash evaporation analysis unit comprises a flash evaporation kettle, which has at least two stages of flash evaporation chambers and a bottom liquid storage tank from top to bottom.

[0014] The upper section of the flash kettle is a primary flash chamber, and the lower section is a secondary flash chamber. The bottom liquid storage tank is divided into a lean liquid tank and a semi-lean liquid tank by at least one overflow plate. A primary flash atomizer is arranged on the upper part of the primary flash chamber, and a primary flash guide plate is arranged on the bottom; a secondary flash atomizer is arranged on the upper part of the secondary flash chamber, and a secondary flash guide plate is arranged in a part of the lower part of the secondary flash chamber located above the semi-lean liquid tank, and the remaining area is communicated with 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 through an air stripping gas guide pipe, the semi-lean liquid tank is connected to the secondary flash atomizer through a semi-lean liquid-flue gas heat exchanger and a semi-lean liquid electric auxiliary heater, and the primary flash chamber is connected to the semi-lean liquid tank through a primary flash guide pipe.

[0015] The rich liquid at the bottom of the absorption tower is heated to 60-65°C and then sent to the first-level flash atomizer of the first-level flash chamber of the flash kettle for spraying for flash evaporation; the semi-lean liquid after the first-level flash evaporation falls into the semi-lean liquid tank, and then is extracted and heated to 65-70°C and sent to the second-level flash atomizer of the second-level flash chamber for spraying for second-level flash evaporation, and the obtained lean liquid falls into the lean liquid tank and is then led out of the flash kettle and sent into the liquid holding column; the gas phase of the second-level flash chamber and the gas phase of the first-level flash chamber are led out of the flash kettle under negative pressure and sent to the flash steam condenser.

[0016] The flash evaporation and analysis unit comprises a flash evaporation kettle and a rich liquid reflux washing tower, and the upper section of the primary flash evaporation chamber of the flash evaporation kettle is also provided with a reflux rich liquid atomizer;

[0017] The rich liquid from the absorption tower is divided into two streams. The first stream of rich liquid is heated to 60-65°C and then sent to the first-stage flash atomizer of the flash kettle for spraying and analysis to recover the styrene component; the second stream of rich liquid is sent to the rich liquid reflux washing tower for heat exchange with the gas phase washing from the flash kettle;

[0018] The rich liquid from the rich liquid reflux washing tower is also divided into two streams. The first stream is sent to the reflux rich liquid atomizer of the flash kettle for spraying and analyzing to recover the styrene component. The second stream is mixed with the first stream from the absorption tower, heated to 60-65°C, and then sent to the primary flash atomizer of the flash kettle for spraying.

[0019] The gas phase out of the flash kettle is washed and heat-exchanged with the second stream of rich liquid from the absorption tower through the rich liquid reflux washing tower and then sent to the flash steam condenser.

[0020] The first stream of rich liquid from the absorption tower is heat exchanged with the lean liquid from the holding liquid column, and then further heated to 60-65°C before being sent to the flash kettle.

[0021] Inert gas components with a boiling point lower than styrene and insoluble in the absorbent are introduced into the lean liquid tank and the semi-lean liquid tank in the flash kettle to further strip the residual styrene components in the lean liquid and the semi-lean liquid. These inert gas components are water vapor, or a mixture of water vapor and nitrogen or carbon dioxide.

[0022] The stripping gas escaping from the semi-lean liquid tank is introduced into the primary flash chamber through the stripping gas guide pipe and the demister; the stripping gas escaping from the lean liquid tank directly enters the secondary flash chamber, and the gas phase in the primary flash chamber and the secondary flash chamber is drawn out of the flash kettle under the suction action of the vacuum pump.

[0023] The gas phase from the flash chamber is separated into condensate and non-condensable gas through a flash steam condenser, and the condensate is separated into styrene component and condensed water through a pre-pump oil-water separator. The separated condensed water is heated and vaporized by a condensate-flue gas vaporizer and then introduced into the lean liquid tank and semi-lean liquid tank in the flash kettle as water vapor to strip the styrene component in the lean liquid and semi-lean liquid, thereby realizing condensed water circulation.

[0024] The non-condensable gas separated by the flash steam condenser is pumped out by a vacuum pump and mixed with the tail gas from the demister tower.

[0025] The high-temperature flue gas above 800°C drawn out from the incinerator is heat exchanged with the desorbed gas of the rotary unit through the desorbed gas heat exchanger to form a medium-temperature flue gas with a temperature of 230-250°C, which is then divided into three streams. The first stream is indirectly heat exchanged with the semi-lean liquid from the semi-lean liquid tank to form a low-temperature flue gas for external discharge, the second stream is indirectly heat exchanged with the condensed water sent to the flash kettle for stripping to vaporize the condensed water to form a low-temperature flue gas for external discharge, and the third stream is heat exchanged with the rich liquid from the absorption tower to form a low-temperature flue gas, which is circulated in the RTO incinerator by regulating the flow rate through the flue gas circulation valve, and the rest is discharged through the external exhaust flue gas valve.

[0026] The incinerator draws out low-temperature flue gas of 100-120°C and divides it into two streams. One stream is mixed with the third medium-temperature flue gas and then passes through a heat exchanger to heat the rich liquid from the absorption tower, and the other stream is discharged externally for emergency.

[0027] Control the negative pressure of the flash kettle, flash steam condenser and oil-water separator before the pump to below 4kPa absolute pressure.

[0028] In view of the problems existing in the background technology, the inventors set up a rotary unit, coupled absorption and adsorption, and combined it with a flash evaporation unit to achieve the purification of waste gas from the artificial stone production line to meet emission standards and the recovery of styrene components in the tail gas. The specific improvements are as follows:

[0029] (1) A two-stage rotor unit is set up to adapt to the purification of VOC (styrene) tail gas in different environments. According to the different concentrations of styrene in the exhaust gas, you can choose to open all or individually, which is flexible. In winter, the temperature is low and the concentration of VOC (styrene) in the VOC (styrene) tail gas is low, so you only need to start the first-stage rotor. In summer, the temperature is high and the concentration of VOC (styrene) in the VOC (styrene) tail gas is high, so you need to start the two-stage rotor. On the other hand, in summer, the first-stage rotor adsorbs and concentrates to produce a high-concentration first-stage concentrated gas that enters the absorption tower, which is beneficial to increase the absorption of styrene by the unit absorbent, save the power consumption of the absorption unit, reduce the amount of rich liquid analysis, and reduce the energy consumption of the analysis process. The second-stage rotor adsorption ensures that the exhaust gas meets the standards.

[0030] (2) The incinerator is configured to recover the residual energy that cannot be concentrated to meet the enthalpy requirements of the desorption, distillation and other units within the system. The incinerator provides high-temperature and low-temperature flue gases. The high-temperature flue gas is used to heat the desorption gas heat exchanger of the rotor and is further reused. The third flue gas is also controlled by the flue gas circulation valve to return to the incinerator for circulation. Its functions are as follows: ① It is conducive to improving the stability of the combustion of the exhaust gas entering the incinerator. The appropriate circulation volume can ensure that there is enough low-temperature flue gas generated, thereby ensuring that the heat storage in the incinerator is sufficient, thereby increasing the temperature of the exhaust gas entering the furnace hall; ② Reasonably adjust the circulation volume to effectively control the amount of high-temperature flue gas above 800℃ and the amount of low-temperature flue gas of 110℃-120℃ drawn from the incinerator, and ensure the optimal distribution of heat required by the heat exchange equipment of the rotor adsorption unit and the flash evaporation analysis unit (reasonable circulation volume can achieve the high-temperature flue gas above 800℃ and the low-temperature flue gas of 110℃-120℃ drawn from the incinerator. value to meet the heat demand of each heating medium); ③ Reduce the concentration of styrene in the concentrated gas entering the incinerator, improve the combustion effect of the styrene component, which is beneficial to reduce the VOC concentration of the exhaust gas. The high-temperature flue gas is used to heat the desorption gas heat exchanger of the rotor, and realize the multi-stage utilization of the flue gas. The heat energy of the low-temperature flue gas is also effectively recovered and utilized.

[0031] (3) The flash evaporation and desorption unit is provided with a rich liquid reflux washing tower to realize the reflux of rich liquid. The flash evaporation and desorption unit includes a flash evaporation kettle and a rich liquid reflux washing tower. The rich liquid reflux washing tower is arranged downstream of the gas phase outlet of the flash evaporation kettle. Under the suction action of the vacuum pump, the flash vapor after atomization and flash evaporation of the flash evaporation kettle enters the rich liquid reflux washing tower through the gas phase outlet of the flash evaporation kettle, and contacts with the rich liquid from the absorption tower sprayed from the top of the tower through the packing layer in countercurrent, exchanges heat and captures fine droplets.

[0032] The rich liquid reflux has the following functions: 1) Cooling and recovery of cold source. In the rich liquid reflux washing tower, the low-temperature rich liquid is in direct countercurrent contact with the flash steam, which cools the flash steam, has high cooling efficiency, and has high cold recovery efficiency of the low-temperature rich liquid; 2) Droplet capture, reducing absorbent loss. Under the action of surface tension, when the rich liquid sprayed into the tower encounters fine droplets, the fine droplets are very easy to merge on the surface of the droplets formed by the spray; 3) It has a distillation effect. When the rich liquid enters the rich liquid reflux washing tower, the flash steam temperature is higher than that of the rich liquid, and the flash steam pressure is lower than the pressure when the rich liquid is saturated (that is, the rich liquid is already an absorbent liquid that has reached saturation under normal pressure). During the flow of the rich liquid entering the tower from top to bottom, due to direct contact and heat exchange with the flash steam, the temperature becomes higher and higher, and the styrene component in the rich liquid is continuously volatilized; during the upward flow of the flash steam entering from the lower part of the tower, the temperature becomes lower and lower, and the styrene concentration becomes higher and higher; 4) Improve the efficiency of condensation and recovery of styrene by the condenser. After the flash steam passes through the rich liquid reflux washing tower, the styrene concentration is increased, and the steam temperature is greatly reduced, which is conducive to the condensation and recovery of the styrene component after the condenser; 5) A moisture enrichment layer is formed to improve the styrene flash evaporation effect. After the rich liquid enters the rich liquid reflux washing tower, a low temperature zone is formed in the tower relative to the entire flash steam pipeline. Since the water vapor partial pressure in the flash steam is much higher than the styrene partial pressure, and the saturated vapor pressure of water is within the operating temperature range, it is greatly affected by temperature (7.381 kPa at 40°C; 19.932 kPa at 60°C), a large amount of water condenses into the rich liquid. The rich liquid enters the flash kettle through the first-stage flash atomizer for first-stage flash evaporation. Almost all the water in the rich liquid is vaporized and enters the flash steam. After the rich liquid reflux washing tower, most of it is condensed again. The water cycle is like this, the water vapor concentration in the first-stage flash steam becomes higher and higher, and the reflux rich liquid condenses and absorbs more and more water until a balance state of reflux rich liquid absorbing water is formed. According to experimental verification, when the diethyl phthalate solution that absorbs styrene is distilled, adding a certain amount of water into the absorption liquid can significantly improve the distillation effect.

[0033] (4) A multi-layer structure is set in the flash kettle for multi-stage flash evaporation. A multi-stage flash chamber is set in the flash kettle, and a gas stripping section is set at the bottom of the kettle. The multi-stage flash evaporation and gas stripping are organically combined to improve the distillation effect of the rich liquid, save space, improve the vacuum pump effect, save the operating cost of the vacuum pump, and the equipment structure is compact and safe.

[0034] The flash evaporation kettle of the flash evaporation analysis unit has at least two flash evaporation chambers, and correspondingly connected lean liquid tanks and semi-lean liquid tanks are arranged. The rich liquid is first introduced into the upper first-stage flash evaporation chamber and sprayed out by the first-stage flash evaporation atomizer for flash evaporation. The semi-lean liquid after flash evaporation falls into the semi-lean liquid tank through the first-stage flash evaporation guide pipe, and then is drawn out and heated by the semi-lean liquid heater and sent to the second-stage flash evaporation chamber of the lower stage for spraying by the second-stage flash evaporation atomizer for secondary flash evaporation. The lean liquid falls into the lean liquid tank through the second-stage flash evaporation guide plate. The front end of the second-stage flash evaporation guide plate is inserted below the liquid level of the lean liquid tank to form a liquid seal, which separates the second-stage flash evaporation chamber from the gas stripping area above the semi-lean liquid tank. On the one hand, by arranging two-stage flash evaporation in one flash evaporation kettle, the analysis effect is enhanced. On the other hand, the first-stage flash evaporation chamber and the second-stage flash evaporation chamber are not connected to each other, so as to ensure the flash evaporation effect.

[0035] An aeration head is set in the lean liquid tank and the semi-lean liquid tank. The condensate from which the non-condensable gas and styrene components are separated after flash evaporation is heated and vaporized by a heater, and then introduced into the aeration head in the form of water vapor. The lean liquid tank and the semi-lean liquid tank can be stripped, thus truly realizing the reuse of the condensate. The introduction of stripping gas enhances the airflow in the flash evaporation area. The styrene gas phase concentrated in the flash evaporation area is brought out through the flow of stripping gas, diluting the styrene in the gas phase around the atomized droplets, enhancing the volatilization effect of styrene, and improving the flash evaporation efficiency.

[0036] (6) Setting a liquid holding column to eliminate "cavitation". Considering the problem of "cavitation" when the lean liquid is drawn out from the bottom of the flash kettle, a liquid holding column is set to increase the pressure before the pump to extract the lean liquid. Since the working pressure of the flash kettle is maintained below 4 kPa (absolute pressure), which is much lower than the atmospheric pressure, when the lean liquid is directly drawn out from the bottom of the flash kettle through a pump and enters the absorption-adsorption unit at normal pressure, the pressure difference before and after the pump is large, and the residual styrene components and dissolved water in the lean liquid will produce "cavitation", which not only affects the stability of the pump operation, but also causes the pump blades to be impacted and corroded. Setting a liquid holding column to draw the lean liquid from the bottom of the liquid holding column into the absorption tower increases the liquid phase pressure at the pump inlet, effectively overcoming the "cavitation" phenomenon.

[0037] (7) Install a vacuum pump, flash steam condenser and oil-water separator before the pump. The vacuum pump is used to 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. A flash steam condenser is installed upstream of the vacuum pump to cool and condense the flash steam, reduce the volume of the flash steam, improve the efficiency of the vacuum pump, and reduce the operating cost of the vacuum pump.

[0038] The reason why the flash pressure below 4kPa is selected is due to the following factors: First, to reduce the polymerization of the recovered styrene components. When the temperature of styrene reaches 60°C, the polymerization rate intensifies. When it is below 4kPa, the boiling point of styrene is lower than 55°C, and the polymerization of styrene at this temperature can be ignored; secondly, under an absolute pressure of 4kPa, the rich liquid temperature only needs to be controlled at around 60°C to achieve a higher analysis effect, and the temperature resistance requirements for the equipment and its sealing materials are not high, which reduces equipment investment; thirdly, the operating pressure of 4kPa can save investment and operating costs. When the operating pressure is too low, the load of the vacuum pump used increases, and at the same time, the equipment strength and sealing requirements of the vacuum system are higher. When the operating pressure is higher than 4kPa, it is not conducive to the analysis of styrene.

[0039] (8) Set up a pre-pump oil-water separator. Control the amount of condensed water discharged from the pre-pump oil-water separator to the condensate tank, increase the oil-water interface level in the pre-pump oil-water separator, and discharge excess water from the condensate. Since part of the water vapor brought in by the tail gas during the absorption process is absorbed by the absorbent, during flash evaporation, the boiling point of water is lower than that of styrene, and the water vaporizes first and enters the flash steam together with the water vapor introduced. After condensation, it enters the condensate, breaking the water balance of the system, and the excess water needs to be discharged. Keeping the amount of condensed water discharged from the pre-pump oil-water separator to the condensate tank constant and raising the oil-water interface to a higher position is conducive to discharging the water absorbed by the absorbent from the tail gas together with the oil phase, thereby reducing the styrene concentration in the water phase; it is conducive to improving the styrene recovery rate. Because the higher the level of the oil-water interface, the more thorough the oil phase separation at the water phase outlet level, thereby reducing the styrene concentration in the water vapor circulating into the flash evaporator.

[0040] (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 kettle as a stripping gas. Experiments show that when the rich liquid contains a certain amount of water, the styrene desorption rate increases significantly. Since the water vapor partial pressure in the flash steam is much higher than the styrene partial pressure, and the saturated vapor pressure of water is greatly affected by temperature within the operating temperature range (7.381 kPa at 40°C and 19.932 kPa at 60°C), the rotary evaporation experiment shows that the maximum desorption rate is achieved when all the water in the rich liquid is evaporated (that is, when the water phase disappears). This technical solution aerates the lean liquid and semi-lean liquid with water vapor for a long time (about 75 kg / h, 3000 m3), with a high gas-liquid ratio of about 200-300:1, which is beneficial to further reduce the residual styrene concentration in the lean liquid.

[0041] Beneficial effects:

[0042] The present invention can realize ultra-purification and discharge of waste gas from artificial stone production lines, and at the same time recover VOC components of waste gas, with low investment and operation costs, good tail gas purification effect, effective coupling of absorption and adsorption, energy saving and consumption reduction, high styrene recovery rate, and environmental friendliness. The present invention can remove more than 99.9% of pollutants from waste gas from artificial stone production lines, recover more than 98% of styrene components in styrene tail gas, purify tail gas for ultra-clean discharge, and absorbent consumption is less than 0.1kg / t-styrene. Compared with the distillation process, it saves more than 50% of energy consumption and reduces more than 50% of operation costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a system diagram of Example 1 of the present invention.

[0044] Figure 2 This is a system diagram of Example 2 of the present invention.

[0045] Figure 3 This is a fitting curve diagram of the Henry constant determined experimentally in the present invention.

[0046] Among them, 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 rotor; 3b: secondary rotor; 4a: primary desorption gas heat exchanger; 4b: secondary desorption gas heat exchanger; 4c: inlet and outlet gas heat exchanger; 4d: inlet gas cooler; 4e: rich liquid-flue gas heat exchanger; 4f: lean-rich liquid heat exchanger; 4g: inlet lean liquid cooler; 4h: flash steam condenser; 4j: condensed water-flue gas gasifier; 4k: semi-lean liquid-flue gas heat exchanger; 5: rich liquid reflux scrubber; 5-1: flash steam demister; 6: demister; 7 : Absorption tower; 8: Absorption liquid intermediate tank; 9a: Primary spray pump; 9b: Secondary spray pump; 9c: Third-stage spray pump; 9d: Primary flash pump; 9e: Secondary flash pump; 9f: Lean liquid discharge pump; 9g: Auxiliary discharge pump; 9h: Rich liquid reflux pump; 9j: Condensate pump; 10a: Rich liquid electric auxiliary heater; 10b: Semi-lean liquid electric auxiliary heater; 11a: Rich liquid intermediate tank; 11b: Condensate tank before vacuum pump; 12a: Primary flash demister; 12b: Secondary flash demister; 12c: Stripping demister; 13: Flash kettle; 13-1: Reflux rich liquid atomizer; 13-2: Primary flash atomizer; 13-3: Secondary flash atomizer ;13-4: primary flash guide plate;13-5: primary flash guide pipe;13-6: secondary flash guide plate;13-7: air stripping guide pipe;13-8: secondary flash guide pipe;13-9: primary flash guide pipe;13-10: lean liquid tank;13-11: semi-lean liquid tank;13-12: lean liquid aeration head;13-13: semi-lean liquid aeration head;14: liquid holding column;14-1: lean liquid overflow pipe;15: pre-pump oil-water separator;16: intermediate oil tank;17: vacuum unloading valve;18: vacuum pump;19: incinerator;20a: flue gas discharge emergency valve;20b: rich liquid heating flue gas valve;20c: flue gas circulation valve;20d : Semi-lean liquid heating flue gas valve; 20e: Condensed water vaporization flue gas valve; 20f: Purge gas regulating valve; 20g: First-level high-temperature flue gas valve; 20h: Second-level high-temperature flue gas valve; 20j: Tower inlet concentrated gas valve; 20k: Furnace inlet concentrated gas valve; 20m: External exhaust flue gas valve; 20n: Rich liquid heating emergency valve; 20p: First-level rotary air inlet valve; 20q: Second-level rotary air inlet valve; 20r: First-level desorption air valve; 20s: Second-level desorption air valve; 20t: Tail gas check valve; 20u: Second-level tower inlet flue gas valve; 20v: Second-level wheel inlet flue gas valve; 20w: Furnace fresh air valve; 20x: Furnace inlet flue gas main valve; 21: Lower explosion limit detector; 22: Filter. DETAILED DESCRIPTION

[0047] The system of the present invention is explained below in conjunction with the accompanying drawings:

[0048] System Example 1:

[0049] See also Figure 1 , the system of the present invention sequentially connects the rotor unit, the absorption tower 7 and the flash analysis unit; wherein, the rotor unit includes two stages of rotors connected in series and corresponding desorption gas heat exchangers, the purified gas outlet of the first-stage rotor 3a is connected to the external exhaust pipe via the second-stage rotor 3b; the cooled gas outlet of the first-stage rotor 3a is connected back to the first-stage rotor 3a via the first-stage desorption gas heat exchanger 4a, and similarly, the cooled gas outlet of the first-stage rotor 3b is connected back to the first-stage rotor 3a via the first-stage desorption gas heat exchanger 4b; the specific connection relationship and working principle of each component of the rotary unit are prior art and will not be described in detail here. The concentrated gas outlet of the first-stage rotor 3a is divided into two routes through the first-stage desorption fan 1b, one route is connected to the gas phase inlet of the absorption tower 7 via the tower inlet cooler 4d, and the other route is connected to the incinerator 19 (preferably an RTO incinerator). The concentrated gas outlet of the second-stage rotor 3b is connected to the incinerator 19.

[0050] The exhaust gas pipeline is divided into three routes after passing through the main fan 1a. The first and second routes are connected to the desorption gas inlet and the exhaust gas inlet of the rotor unit through the first-level desorption gas valve 20r and the first-level rotor air intake valve 20p respectively, and the third route is connected to the air intake of the second-level rotor 3b through the second-level rotor air intake valve 20q.

[0051] The absorption tower can be a conventional absorption tower, or a conventional absorption tower such as Figure 1 The absorption tower 7 with the absorption liquid intermediate tank 8 is shown, wherein at least three spray layers are arranged from top to bottom in the middle of the absorption tower 7, and each spray layer corresponds to an independent absorption liquid intermediate tank 8; the absorption liquid intermediate tank of the upper layer is connected to the absorption liquid intermediate tank of the lower layer through a full flow pipe.

[0052] The gas phase outlet of the absorption tower 7 is connected to the exhaust gas pipeline via a demister 6 .

[0053] The flash evaporation analysis unit includes a flash evaporation kettle 13 and a liquid holding column 14. The flash evaporation kettle 14 has at least two flash evaporation chambers and a lower storage tank from top to bottom. In this embodiment, the upper section of the flash evaporation kettle 14 is a primary flash evaporation chamber, the lower section is a secondary flash evaporation chamber, and the bottom storage tank is divided into a lean liquid tank 13-10 and a semi-lean liquid tank 13-11 by an overflow plate. The upper part of the primary flash evaporation chamber is provided with a 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 evaporation chamber is provided with a secondary flash evaporation atomizer 13-3, and a part of the lower part of the secondary flash chamber located above the semi-lean liquid tank is provided with a secondary flash evaporation guide plate 13- 6, the remaining area is connected to the lean liquid tank 13-10; the front end of the secondary flash guide plate 13-6 is inserted into the lean liquid tank 13-10; the secondary flash guide plate 13-6 and the overflow plate separate the semi-lean liquid tank 13-11 from the secondary flash chamber; the gas phase space above the semi-lean liquid tank 13-11 is connected to the primary flash chamber through the gas stripping gas guide pipe 13-7, and the primary flash chamber is connected to the semi-lean liquid tank 13-11 through the primary flash guide pipe 13-5;

[0054] The rich liquid outlet of the absorption tower 7 is connected to the primary flash atomizer 13-2 via the rich liquid intermediate tank 11a, the primary 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 semi-lean liquid tank 13-11 is connected to the secondary flash atomizer 13-3 via the secondary 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 primary flash chamber and the secondary flash chamber are connected to the flash steam condenser 4h via the corresponding primary flash demister 12a and secondary flash demister 12b.

[0055] The condensate outlet of the flash steam condenser 4h is connected to the pre-pump oil-water separator 15, and the condensate outlet of the pre-pump oil-water separator 15 is connected to the lean liquid aeration head 13-13 in the lean liquid tank 13-10 and the semi-lean liquid aeration head 13-12 in the semi-lean liquid tank 13-11 in the flash kettle 13 through the pre-exhaust pump condensate tank 11b, the condensate pump 9j, and the condensate-flue gas vaporizer 4j. The non-condensable gas outlet of the flash steam condenser 4h is connected to the exhaust gas pipeline through the exhaust pump 18.

[0056] The lean liquid outlet at the bottom of the liquid holding column 14 is connected to the absorption liquid inlet of the upper section of the absorption tower 7 through the lean-rich liquid heat exchanger 4e and the lean liquid cooler 4g, and the overflow port at the top is connected to the lean liquid tank 13-10 in the flash kettle 13 through the lean liquid overflow pipe 14-1.

[0057] The high-temperature flue gas outlet of the incinerator 19 is divided into two routes, which are respectively merged into one route after passing through the desorber heat exchangers corresponding to the two-stage wheels (the first-stage desorbed gas heat exchanger 4a and the second-stage desorbed gas heat exchanger 4b), and then divided into three routes after passing through the high-temperature flue gas exhaust fan 1e. The first route is connected to the external exhaust pipe through the semi-lean liquid-flue gas heat exchanger 4k, the second route is connected to the external exhaust pipe through the condensed water-flue gas vaporizer 4j, and the third route is divided into two routes after passing through the rich liquid-flue gas heat exchanger 4e, one route is connected to the incinerator 19 through the flue gas circulation valve 20c, and the other route is connected to the external exhaust pipe through the external flue gas valve 20m.

[0058] The low-temperature flue gas outlet of the incinerator 19 is divided into two paths through 1f, one of which is connected to the rich liquid-flue gas heat exchanger 4e, and the other is connected to the external discharge pipeline through the flue gas external discharge emergency valve 20a.

[0059] Process Example 1:

[0060] Take a certain artificial stone production plant as an example. The plant has 4 artificial stone production lines. The VOC production units mainly come from mixing, feeding, unloading, spreading, vacuuming, pressing, film lifting, and drying. The main pollutants are styrene, non-methane total hydrocarbons, etc. During the collection process, the tail gas rich in styrene is 95,000-105,000 Nm 3 / h, the concentration of styrene in tail gas is 1500-2000mg / Nm in summer 3 , 300-500mg / Nm in winter 3 The heat enthalpy required by the exhaust gas purification system is provided by the system itself.

[0061] refer to Figure 1 The implementation process is divided into two different working conditions: summer and winter. The specific operations are as follows:

[0062] Summer: The temperature is high in summer, and the concentration of styrene in the tail gas from the production line is high, 1500-2000mg / Nm 3 .

[0063] 1) Wheel adsorption

[0064] Close the secondary rotor air inlet valve 20q, and the styrene tail gas on the production line is collected and blown into the primary rotor 3a through the exhaust gas pipeline under the suction action of the main fan 1a, and enters the secondary rotor 3b after adsorption, and is further adsorbed and purified before being discharged.

[0065] 2) Desorption

[0066] While the primary wheel 3a and the secondary wheel 3b are adsorbing, the primary desorption gas valve 20r and the secondary desorption gas valve 20s are opened. Under the suction action of the primary desorption fan 1b and the secondary desorption fan c, the desorption gas first cools the wheel. The cooled gas enters the primary desorption gas heat exchanger 4a and the secondary desorption gas heat exchanger 4b respectively for indirect heat exchange with the flue gas of about 850°C drawn out from the incinerator 19. The temperature of the desorption gas rises to about 210°C and then enters the wheel for desorption.

[0067] 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.

[0068] The concentration of styrene in the primary concentrated gas is monitored in real time by a lower explosion limit detector 21 .

[0069] 3) Concentrated gas absorption tower absorption

[0070] Under the suction action of the first-stage desorption fan 1b, the first-stage desorption gas (first-stage concentrated gas, styrene concentration 11000-12000mg / Nm3) is divided into two parts. One part is introduced into the absorption tower 7, and the styrene absorption component in the concentrated gas is removed by the absorption liquid; according to the thermal balance requirement of the system, a part of the first-stage desorption gas is separated and mixed with the second-stage desorption gas to be incinerated in the incinerator 19 as a balancing measure for the thermal enthalpy requirement of the system.

[0071] The concentrated gas enters the tower from the lower air inlet of the absorption tower 7, and contacts with the absorption liquid (diethyl phthalate absorbent) sprayed from the upper part of the tower in countercurrent, and most of the styrene components in the concentrated gas are absorbed.

[0072] The concentrated gas from the absorption tower 7 enters the demister tower 6 to remove the mist droplets and is mixed with the non-condensable gas discharged by the vacuum pump 18, introduced into the air inlet of the main fan 1a, mixed with the exhaust gas from the production line and then enters the rotor unit for adsorption.

[0073] The absorption process is as follows:

[0074] ① The absorption liquid is sprayed into the tower in three layers. The lean liquid from the flash evaporation analysis unit enters the absorption liquid intermediate tank 8 as the absorbent and is mixed with the absorption liquid extracted from the upper layer by the primary spray pump 9a and sprayed into the absorption tower 7. The absorption liquid contacts the concentrated gas in countercurrent through the upper packing layer, and part of the styrene component in the concentrated gas is absorbed; the lean liquid and the supplementary fresh absorbent / liquid (diethyl phthalate) are added through the pump head of the primary spray pump 9a.

[0075] ② The absorption liquid flowing through the upper packing layer flows back into the upper layer of the absorption liquid intermediate tank 8, and is circulated and sprayed through the first-level spray pump 9a; an overflow pipe is set on the upper layer of the absorption liquid intermediate tank 8, and the excess absorption liquid flows to the lower layer of the absorption liquid intermediate tank 8 through the overflow pipe.

[0076] ③ The absorption liquid in the lower layer of the absorption liquid intermediate tank 8 is sprayed into the absorption tower 7 through the secondary spray pump 9b, and contacts with the concentrated gas in countercurrent through the middle packing layer, and part of the styrene component in the concentrated gas is absorbed.

[0077] ④ The absorption liquid flowing through the middle packing layer flows into the lower storage tank of the absorption tower 7, and is circulated and sprayed through the secondary spray pump 9b; an overflow pipe is set in the middle layer of the absorption liquid intermediate tank 8, and the excess absorption liquid flows to the lower storage tank of the absorption tower 7 through the overflow pipe.

[0078] ⑤ A part of the absorption liquid in the liquid storage tank at the lower part of the absorption tower 7 is sprayed into the absorption tower 7 through the three-stage spray pump 9c, and contacts with the concentrated gas in countercurrent through the lower packing layer, and part of the styrene component in the concentrated gas is absorbed.

[0079] ⑥ The absorption liquid flowing through the lower packing layer enters the lower storage tank of the absorption tower 7 and is circulated and sprayed by the three-stage spray pump 9c; the absorption liquid is sprayed into the absorption tower 7, and contacts with the concentrated gas in countercurrent through the middle packing layer, and part of the styrene component in the concentrated gas is absorbed.

[0080] ⑦ The rich liquid sent to the flash evaporation analysis unit is led out through the three-stage spray pump 9c.

[0081] 4) Concentrated gas styrene incineration for heat generation

[0082] Under the suction effect of the secondary desorption fan 1c, the secondary desorption gas (secondary concentrated gas, styrene concentration 5000-6000mg / Nm 3 ) is introduced into the incinerator 19 for incineration, generating high-temperature flue gas of 850°C and low-temperature flue gas of 110-115°C.

[0083] When the styrene concentration in the tail gas from the production line is high, in order to control the styrene concentration in the first-stage desorbed gas below the lower explosion limit, the first-stage desorbed gas flow rate needs to be increased, and the enthalpy required for heating the first-stage desorbed gas is correspondingly increased. The enthalpy generated by the incineration of the second-stage desorbed gas into the incinerator 19 cannot meet the enthalpy demand of the system, and part of the first-stage desorbed gas (first-stage concentrated gas, styrene concentration 11000-12000mg / Nm 3 ) is mixed with the secondary concentrated gas and enters the incinerator 19 for incineration and heat extraction. The flow rate of the primary concentrated gas entering the incinerator 19 is regulated by the tower concentrated gas valve 20j and the furnace concentrated gas valve 20k.

[0084] When the concentration of styrene in the tail gas from the production line is high, the explosion lower limit detector 21 detects that the concentration of styrene in the primary desorption gas exceeds the set lower limit. The primary desorption gas flow rate is increased by adjusting the primary desorption gas valve 20r, and the amount of high-temperature flue gas entering the primary desorption gas heat exchanger 4a is increased. Due to the increase in the amount of high-temperature flue gas drawn out, the heat production of the incinerator 19 needs to be increased. The amount of primary desorption gas entering the incinerator 19 is increased by adjusting the concentrated gas valve 20k to supplement the system enthalpy demand.

[0085] 5) Rich liquid flash evaporation analysis styrene recovery

[0086] ① 15-20t / h of rich liquid is drawn from the lower storage tank of the absorption tower 7 into the rich liquid intermediate tank 11a, and then pumped out by the first-stage flash pump 9d and sequentially enters the rich liquid-flue gas heat exchanger 4e and the lean-rich liquid heat exchanger 4f for heat exchange and temperature rise, and then enters the flash kettle 13 for the first-stage flash evaporation.

[0087] ② Under the suction action of the vacuum pump, the pressure in the flash kettle 13 is controlled at about 4 kPa.

[0088] ③ The rich liquid in the rich liquid intermediate tank 11a is pumped out by the first-stage flash pump 9d, firstly exchanges heat with the lean liquid from the flash analysis unit, and then exchanges heat with the low-temperature flue gas from the incinerator 19, is heated to 60-65°C, and then is atomized by the first-stage flash atomizer 13-2 and enters the flash kettle 13. Under negative pressure, 30-40% of the styrene component in the rich liquid evaporates into the flash steam, and the semi-lean liquid from which part of the styrene has evaporated flows into the semi-lean liquid tank 13-11 through the first-stage flash guide plate 13-4 and the first-stage flash guide pipe 13-5.

[0089] ④ The semi-lean liquid in the semi-lean liquid tank 13-11 is pumped out by the secondary flash pump 9e and heated to 65-70°C by the semi-lean liquid-flue gas heat exchanger 4k, and then atomized by the secondary flash atomizer 13-3 and enters the flash kettle 13 for secondary flash evaporation. The styrene component in the semi-lean liquid further evaporates and enters the flash steam; the lean liquid with about 20-30% of the styrene component remaining is introduced into the lean liquid tank 13-12 through the secondary flash guide plate 13-6.

[0090] ⑤ Introduce water vapor 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, further gas lift the lean liquid and the semi-lean liquid, and further reduce the styrene concentration in the lean liquid and the semi-lean liquid.

[0091] ⑥ The stripping gas and flash steam are respectively led out through the stripping gas duct 13-7, the secondary flash evaporation duct 13-8, and the primary flash evaporation duct 13-9, and are defogged by the stripping demister 12c, the secondary flash demister 12b, and the primary flash demister 12a, and then enter the rich liquid reflux washing tower 5 under the suction action of the vacuum pump 18.

[0092] ⑦ The lean liquid after flash evaporation is pumped out from the lean liquid tank 13-10 into the liquid holding column 14 through the auxiliary discharge pump 9g, and then pumped out from the bottom of the liquid holding column 14 through the lean liquid discharge pump 9f, and cooled to 20-30°C through the lean-rich liquid heat exchanger 4f and the tower lean liquid cooler 4g before entering the absorption tower 7; an overflow pipe 14-1 is arranged at the upper part of the liquid holding column 14 to lead out the excess lean liquid back to the lean liquid tank 13-10 to keep the liquid level of the liquid holding column 14 stable.

[0093] ⑧ The cold rich liquid from the absorption tower 7 is sprayed into the reflux washing tower 5 from the upper part, and contacts with the flash steam and stripping gas entering from the lower part of the reflux washing tower 5 in countercurrent, so that 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 defogged by the flash steam demister 5-1 and then enter the flash steam condenser for 4 hours. During the countercurrent contact between the rich liquid, the flash steam and stripping gas, the fine droplets in the flash steam and stripping gas are captured by the rich liquid. The rich liquid after heating up and capturing the droplets is atomized by the rich liquid reflux pump for 9 hours and enters the flash kettle 13 for atomization and flash evaporation.

[0094] ⑨ The flash steam and stripping gas entering the flash steam condenser 4h are cooled by low-temperature refrigerant (7°C low-temperature water), and most of the styrene and water therein are condensed and enter the pre-pump oil-water separator 15 for oil-water separation. The water phase enters the condensate tank 11b, and then is sent to the condensate-flue gas vaporizer 4j through the condensate pump 9j for heating and vaporization to form superheated steam at 60-65°C, which is bubbled into the semi-lean liquid tank 13-11 and the lean liquid tank 13-10; the oil phase, i.e., styrene, is discharged into the intermediate oil tank 16 through the vacuum unloading valve 17 to realize the recovery of the styrene component.

[0095] 6) System heating

[0096] According to the system heat balance analysis, the media that need to be heated include the primary desorbed gas, the secondary desorbed gas, the rich liquid entering the flash kettle 13, and the aeration water vapor. The primary desorbed gas and the secondary desorbed gas need to be heated from about 100°C after the cooling wheel to 220°C, the rich liquid entering the flash kettle 13 needs to be heated from 20-30°C to 60-65°C, and the aeration water vapor entering the flash kettle 13 needs to be heated from condensed water at 20-30°C to 60-65°C.

[0097] ① The secondary desorbed gas and part of the primary desorbed gas are introduced into the incinerator 19 through the incinerator fan 1d for incineration, generating high-temperature flue gas of 850°C and low-temperature flue gas of 110-115°C.

[0098] ② Through the high-temperature flue gas exhaust 1e, high-temperature flue gas of 800-850℃ is drawn out from the high-temperature flue gas outlet of the incinerator 19 with a speed of 5500-6000Nm 3 / h, and is divided into two parts by the first-level high-temperature flue gas valve 20g and the second-level high-temperature flue gas valve 20h, and enters the first-level desorption gas heat exchanger 4a and the second-level desorption gas heat exchanger 4b respectively to exchange heat with the first-level desorption gas and the second-level desorption gas. The temperature of the desorption gas is increased from 100°C to 220°C, and the temperature of the high-temperature flue gas is reduced to 210-250°C;

[0099] ③ The high-temperature flue gas cooled to 210-250℃ is extracted by the high-temperature flue gas exhaust 1e, and is divided into three parts through the semi-lean liquid heating flue gas valve 20d, the condensed water vaporization flue gas valve 20e, and the rich liquid heating emergency valve 20n. One part enters the semi-lean liquid-flue gas heat exchanger 4k to heat the semi-lean liquid, one part enters the condensed water-flue gas vaporizer 4j, and the remaining part is introduced into the incinerator 19 through the incinerator fan 1d for circulation to dilute the concentrated gas entering the furnace.

[0100] ④ Through the low-temperature flue gas exhaust 1f, the low-temperature flue gas of 105-115℃ is drawn out from the low-temperature flue gas outlet of the incinerator 19 with a pressure of 13000-14000Nm 3 / h, and is divided into two parts through the regulation of the rich liquid heating flue gas valve 20b and the flue gas discharge emergency valve 20a. One part enters the rich liquid-flue gas heat exchanger 4e to exchange heat with the rich liquid, and the low-temperature flue gas temperature is cooled from 105-115℃ to 60-70℃; the remaining part is discharged from the chimney through the flue gas discharge emergency valve 20a to adjust the flow rate.

[0101] ⑤ The low-temperature flue gas with a temperature of 60-70°C exiting the rich liquid-flue gas heat exchanger 4e is adjusted through the flue gas circulation valve 20c and the external flue gas valve 20m to adjust the circulating flue gas volume entering the incinerator 19 and the external flue gas volume.

[0102] ⑥ The amount of flue gas discharged from the chimney is adjusted to be as small as possible through the external discharge emergency valve 20a, and the amount of the primary desorption gas introduced into the incinerator 19 is adjusted according to the amount of low-temperature flue gas discharged through the external discharge emergency valve 20a. When the amount of low-temperature flue gas discharged through the external discharge emergency valve 20a is large, the amount of the primary desorption gas introduced into the incinerator 19 is reduced until it is not adjusted to be discharged from the external discharge emergency valve 20a, and the amount of the primary desorption gas entering the absorption tower 7 is increased to increase the absorption amount of styrene.

[0103] 7) Non-condensable gas recovery and treatment

[0104] The pressure in the flash reactor is controlled at 4 kPa, and the amount of gas discharged by the vacuum pump is about 4000 m 3 / h, of which non-condensable gas 10-20% (based on 60m 3 / h), after being cooled to about 20℃ by the flash steam condenser for 4h, the water and most of the styrene components in the flash steam are condensed, and after leaving the vacuum pump, it enters the normal pressure state, and the volume of non-condensable gas is 2.11m 3 / h The remaining non-condensable gas has a high concentration of styrene, about 29g / Nm 3 The amount of styrene carried out by non-condensable gas is about 60g / h.

[0105] When the styrene concentration in the non-condensable gas exceeds the lower limit of styrene explosion concentration, it is promptly mixed and diluted with the concentrated gas after the mist droplets are removed from the absorption tower 7 and the demister tower 6, and then introduced into the air inlet end of the main fan 1a, mixed with the exhaust gas from the production line, and then enters the rotor adsorption to recover the styrene component.

[0106] Winter: Winter temperature is low, and the concentration of styrene from the tail gas of the production line is low, 300-500mg / Nm 3 .

[0107] During winter operation, only the secondary wheel 3b is opened and the primary wheel 3a is closed, that is, the primary wheel air inlet valve 20p is closed and the secondary wheel air inlet valve 20q is opened. The styrene tail gas on the production line is collected and blown into the secondary wheel 3b for adsorption and purification under the suction action of the main fan 1a and then discharged. At the same time, the absorption and flash evaporation analysis units are shut down, and the rest of the operation process is the same as above.

[0108] System Example 2:

[0109] See also Figure 2 , the system of the present invention is connected in sequence to the rotor unit, the absorption tower 7 and the flash evaporation analysis unit;

[0110] Wherein, the rotary unit includes two stages of rotary wheels connected in series and corresponding desorption gas heat exchangers, the purified gas outlet of the first stage rotary wheel 3a is connected to the external exhaust pipe through the second stage rotary wheel 3b; the cooled gas outlet of the first stage rotary wheel 3a is connected to the first stage rotary wheel 3a through the first stage desorption gas heat exchanger 4a, and similarly, the cooled gas outlet of the first stage rotary wheel 3b is connected to the first stage rotary wheel 3a through the first stage desorption gas heat exchanger 4b; the specific connection relationship and working principle of each component of the rotary unit are prior art and will not be described in detail here. The concentrated gas outlet of the first stage rotary wheel 3a (with a lower explosion limit detector 21) is connected to the gas phase inlet of the absorption tower 7 through the first stage desorption fan 1b, the tower concentrated gas valve 20j, the tower inlet and outlet gas heat exchanger 4c, and the tower inlet cooler 4d; the concentrated gas outlet of the second stage rotary wheel 3b is divided into two routes, one route is connected to the tower inlet and outlet gas heat exchanger 4c through the second stage tower inlet flue gas valve 20u, and the other route is connected to the exhaust gas pipeline through the second stage wheel inlet flue gas valve 20v.

[0111] The exhaust gas pipeline is divided into three routes after passing through the main fan 1a. The first and second routes are connected to the desorption gas inlet and the exhaust gas inlet of the rotor unit through the first-level desorption gas valve 20r and the first-level rotor air intake valve 20p respectively, and the third route is connected to the air intake of the second-level rotor 3b through the second-level rotor air intake valve 20q.

[0112] The absorption tower can be a conventional absorption tower, or a conventional absorption tower such as Figure 1 The absorption tower 7 with the absorption liquid intermediate tank 8 is shown, wherein at least three spray layers are arranged from top to bottom in the middle of the absorption tower 7, and each spray layer corresponds to an independent absorption liquid intermediate tank 8; the absorption liquid intermediate tank of the upper layer is connected to the absorption liquid intermediate tank of the lower layer through a full flow pipe.

[0113] The gas phase outlet of the absorption tower 7 is connected to the incinerator 19 through the demister 6 and the inlet and outlet gas heat exchanger 4c;

[0114] The flash analysis unit includes a flash kettle 13 and a liquid holding column 14, and the flash kettle 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 kettle 14 is a primary flash chamber, and the lower section is a secondary flash chamber. 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 provided with a reflux rich liquid atomizer 13-1 and a primary flash atomizer 13-2, and the bottom is a primary flash guide plate 13-4; the upper part of the secondary flash chamber is provided with a secondary flash atomizer 13-3, and a part of the lower part of the secondary flash chamber is located above the semi-lean liquid tank and is provided with a secondary flash atomizer. The guide plate 13-6, the remaining area is connected to the lean liquid tank 13-10; the front end of the secondary flash guide plate 13-6 is inserted into the lean liquid tank 13-10; the secondary flash guide plate 13-6 and the overflow plate separate the semi-lean liquid tank 13-11 from the secondary flash chamber; the gas phase space above the semi-lean liquid tank 13-11 is connected to the primary flash chamber through the gas stripping gas guide pipe 13-7, and the primary flash chamber is connected to the semi-lean liquid tank 13-11 through the primary flash guide pipe 13-5;

[0115] The rich liquid outlet of the absorption tower 7 is divided into two routes, one route is connected to the first-level flash atomizer 13-2 through the rich liquid intermediate tank 11a, the first-level 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, and the other route is connected to the reflux rich liquid atomizer 13-1 of the flash kettle 13 through the rich liquid reflux tower 5 and the rich liquid reflux pump 9h; the semi-lean liquid tank 13-11 is connected to the second-level flash atomizer 13-3 through the second-level 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-level flash chamber and the second-level flash chamber are connected to the rich liquid reflux tower 5 and the flash steam condenser 4h in sequence through the corresponding first-level flash demister 12a and the second-level flash demister 12b.

[0116] The condensate outlet of the flash steam condenser 4h is connected to the pre-pump oil-water separator 15, and the condensate outlet of the pre-pump oil-water separator 15 is connected to the lean liquid aeration head 13-13 in the lean liquid tank 13-10 and the semi-lean liquid aeration head 13-12 in the semi-lean liquid tank 13-11 in the flash kettle 13 through the pre-exhaust pump condensate tank 11b, the condensate pump 9j, and the condensate-flue gas vaporizer 4j. The non-condensable gas outlet of the flash steam condenser 4h is connected to the incinerator 19 through the inlet and outlet tower gas heat exchanger 4c.

[0117] The lean liquid outlet at the bottom of the liquid holding column 14 is connected to the absorption liquid inlet of the upper section of the absorption tower 7 through the lean-rich liquid heat exchanger 4e and the lean liquid cooler 4g, and the overflow port at the top is connected to the lean liquid tank 13-10 in the flash kettle 13 through the lean liquid overflow pipe 14-1.

[0118] The high-temperature flue gas outlet of the incinerator 19 is divided into two routes, which are respectively merged into one route after passing through the desorber heat exchangers corresponding to the two-stage wheels (the first-stage desorbed gas heat exchanger 4a and the second-stage desorbed gas heat exchanger 4b), and then divided into three routes after passing through the high-temperature flue gas exhaust fan 1e. The first route is connected to the external exhaust pipe through the semi-lean liquid-flue gas heat exchanger 4k, the second route is connected to the external exhaust pipe through the condensed water-flue gas vaporizer 4j, and the third route is divided into two routes after passing through the rich liquid-flue gas heat exchanger 4e, one route is connected to the incinerator 19 through the flue gas circulation valve 20c, and the other route is connected to the external exhaust pipe through the external flue gas valve 20m.

[0119] The low-temperature flue gas outlet of the incinerator 19 is divided into two paths through 1f, one of which is connected to the rich liquid-flue gas heat exchanger 4e, and the other is connected to the external discharge pipeline through the flue gas external discharge emergency valve 20a.

[0120] Process Example 2:

[0121] refer to Figure 2 The implementation process is divided into two different working conditions: summer and winter. The specific operations are as follows:

[0122] Summer: The temperature is high in summer, and the concentration of styrene in the tail gas from the production line is high, 1500-2000mg / Nm 3 .

[0123] 1) Wheel adsorption

[0124] Close the secondary rotor air inlet valve 20q, and the styrene tail gas on the production line is collected and blown into the primary rotor 3a through the exhaust gas pipeline under the suction action of the main fan 1a, and enters the secondary rotor 3b after adsorption, and is further adsorbed and purified before being discharged.

[0125] 2) Desorption

[0126] 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 desorption gas first cools the rotor. The cooled gas 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 desorption gas rises to about 210°C, and then enters the rotor for desorption. The desorption gas from the primary rotor 3a, i.e., the primary concentrated gas, enters the absorption tower 7.

[0127] The concentration of styrene in the primary concentrated gas is monitored in real time by the lower explosion limit detector 21, and the concentration of styrene in the primary concentrated gas is controlled at 11-12 g / Nm 3 between.

[0128] The secondary concentrated gas from the secondary rotor 3b is divided into two parts, which are adjusted according to the styrene concentration value in the primary concentrated gas monitored by the secondary tower smoke valve 20u and the secondary wheel smoke valve 20v according to the lower explosion limit detector 21. The secondary wheel smoke valve 20v is kept open. 3 When the secondary flue gas valve is opened by 20u, the secondary concentrated gas is supplemented for dilution. When the concentration is lower than 11g / Nm 3 When , close the secondary flue gas valve into the tower by 20u.

[0129] 3) Concentrated gas absorption tower absorption

[0130] Under the suction of the first-stage desorption fan 1b, the styrene concentration is 11000-12000mg / Nm 3 The first-stage concentrated gas and part of the second-stage concentrated gas are introduced into the absorption tower 7.

[0131] The concentrated gas enters the tower from the lower air inlet of the absorption tower 7, and contacts with the absorption liquid (diethyl phthalate absorbent) sprayed from the upper part of the tower in countercurrent, and most of the styrene components in the concentrated gas are absorbed.

[0132] The concentrated gas from the absorption tower 7 enters the demister tower 6 to remove mist droplets, mixes with the non-condensable gas discharged from the vacuum pump 18, and enters the incinerator 19 to be burned for heat.

[0133] The absorption process is as follows:

[0134] ① The absorption liquid is sprayed into the tower in three layers. The agent from the flash evaporation analysis unit is mixed with the absorption liquid extracted from the upper layer of the absorption liquid intermediate tank 8 by the first-level spray pump 9a and sprayed into the absorption tower 7. The absorption liquid contacts the concentrated gas in countercurrent through the upper packing layer, and part of the styrene component in the concentrated gas is absorbed; the lean liquid and the supplementary fresh absorbent / liquid (diethyl phthalate) are added through the pump head of the first-level spray pump 9a.

[0135] ② The absorption liquid flowing through the upper packing layer flows back into the upper layer of the absorption liquid intermediate tank 8, and is circulated and sprayed through the first-level spray pump 9a; an overflow pipe is set on the upper layer of the absorption liquid intermediate tank 8, and the excess absorption liquid flows to the lower layer of the absorption liquid intermediate tank 8 through the overflow pipe.

[0136] ③ The absorption liquid in the lower layer of the absorption liquid intermediate tank 8 is sprayed into the absorption tower 7 through the secondary spray pump 9b, and contacts with the concentrated gas in countercurrent through the middle packing layer, and part of the styrene component in the concentrated gas is absorbed.

[0137] ④ The absorption liquid flowing through the middle packing layer flows into the lower storage tank of the absorption tower 7, and is circulated and sprayed through the secondary spray pump 9b; an overflow pipe is set in the middle layer of the absorption liquid intermediate tank 8, and the excess absorption liquid flows to the lower storage tank of the absorption tower 7 through the overflow pipe.

[0138] ⑤ A part of the absorption liquid in the liquid storage tank at the lower part of the absorption tower 7 is sprayed into the absorption tower 7 through the three-stage spray pump 9c, and contacts with the concentrated gas in countercurrent through the lower packing layer, and part of the styrene component in the concentrated gas is absorbed.

[0139] ⑥ The absorption liquid flowing through the lower packing layer enters the lower storage tank of the absorption tower 7 and is circulated and sprayed by the three-stage spray pump 9c; the absorption liquid is sprayed into the absorption tower 7, and contacts with the concentrated gas in countercurrent through the middle packing layer, and part of the styrene component in the concentrated gas is absorbed.

[0140] ⑦ The rich liquid sent to the flash evaporation analysis unit is led out through the three-stage spray pump 9c.

[0141] 4) Incineration of concentrated gas from the absorption tower to obtain heat

[0142] The concentrated gas which leaves the absorption tower 7 and is defogged by the demister 6 is introduced into the incinerator 19 for incineration, generating high-temperature flue gas of 850° C. and low-temperature flue gas of 110-115° C. for heat extraction of the system.

[0143] The concentration of styrene in the concentrated gas leaving the absorption tower 7 and defogged by the demister 6 is adjusted according to the required enthalpy of the system and controlled at 4000-6000 mg / Nm 3 between.

[0144] When the system enthalpy demand increases, the frequency of the first-stage spray pump 9a is lowered, the first-stage spraying volume is reduced, the styrene concentration in the concentrated gas out of the tower is increased, and the heat production of the incinerator 19 is increased; when the system enthalpy demand increases, the frequency of the first-stage spray pump 9a is lowered, the first-stage spraying volume is increased, the styrene concentration in the concentrated gas out of the tower is reduced, and the heat production of the incinerator 19 is reduced.

[0145] The styrene concentration in the non-condensable gas exceeds the lower limit of the styrene explosion concentration, and is promptly mixed with the concentrated gas out of the tower and enters the incinerator 19 for incineration and heat extraction.

[0146] 5) Rich liquid flash evaporation analysis styrene recovery

[0147] ① The amount of rich liquid drawn out from the lower storage tank of the absorption tower 7 and entering the flash analysis unit is 15-20 t / h. The rich liquid is divided into two parts. One part (4-6 t / h) enters the rich liquid reflux washing tower 5, and the remaining part (10-15 t / h) enters the rich liquid intermediate tank 11a, and then is pumped out by the first-stage flash pump 9d and enters the rich liquid-flue gas heat exchanger 4e and the lean-rich liquid heat exchanger 4f in turn for heat exchange and temperature rise, and then enters the flash kettle 13 for the first-stage flash evaporation.

[0148] ② Under the suction action of the vacuum pump, the pressure in the flash kettle 13 is controlled at about 4 kPa.

[0149] ③ The rich liquid in the rich liquid intermediate tank 11a is pumped out by the first-stage flash pump 9d, firstly exchanges heat with the lean liquid from the flash analysis unit, and then exchanges heat with the low-temperature flue gas from the incinerator 19, is heated to 60-65°C, and then is atomized by the first-stage flash atomizer 13-2 and enters the flash kettle 13. Under negative pressure, 30-40% of the styrene component in the rich liquid evaporates into the flash steam, and the semi-lean liquid from which part of the styrene has evaporated flows into the semi-lean liquid tank 13-11 through the first-stage flash guide plate 13-4 and the first-stage flash guide pipe 13-5.

[0150] ④ The semi-lean liquid in the semi-lean liquid tank 13-11 is pumped out by the secondary flash pump 9e and heated to 65-70°C by the semi-lean liquid-flue gas heat exchanger 4k, and then atomized by the secondary flash atomizer 13-3 and enters the flash kettle 13 for secondary flash evaporation. The styrene component in the semi-lean liquid further evaporates and enters the flash steam; the lean liquid with about 20-30% of the styrene component remaining is introduced into the lean liquid tank 13-12 through the secondary flash guide plate 13-6.

[0151] ⑤ Introduce water vapor 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, further gas lift the lean liquid and the semi-lean liquid, and further reduce the styrene concentration in the lean liquid and the semi-lean liquid.

[0152] ⑥ The stripping gas and flash steam are respectively led out through the stripping gas duct 13-7, the secondary flash evaporation duct 13-8, and the primary flash evaporation duct 13-9, and are defogged by the stripping demister 12c, the secondary flash demister 12b, and the primary flash demister 12a, and then enter the rich liquid reflux washing tower 5 under the suction action of the vacuum pump 18.

[0153] ⑦ The lean liquid after flash evaporation is pumped out from the lean liquid tank 13-10 into the liquid holding column 14 through the auxiliary discharge pump 9g, and then pumped out from the bottom of the liquid holding column 14 through the lean liquid discharge pump 9f, and cooled to 20-30°C through the lean-rich liquid heat exchanger 4f and the tower lean liquid cooler 4g before entering the absorption tower 7; an overflow pipe 14-1 is arranged at the upper part of the liquid holding column 14 to lead out the excess lean liquid back to the lean liquid tank 13-10 to keep the liquid level of the liquid holding column 14 stable.

[0154] ⑧ The cold rich liquid from the absorption tower 7 is sprayed into the reflux washing tower 5 from the upper part, and contacts with the flash steam and stripping gas entering from the lower part of the reflux washing tower 5 in countercurrent, so that 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 defogged by the flash steam demister 5-1 and then enter the flash steam condenser for 4 hours. During the countercurrent contact between the rich liquid, the flash steam and stripping gas, the fine droplets in the flash steam and stripping gas are captured by the rich liquid. The rich liquid after heating up and capturing the droplets is atomized by the rich liquid reflux pump for 9 hours and enters the flash kettle 13 for atomization and flash evaporation.

[0155] ⑨ The flash steam and stripping gas entering the flash steam condenser 4h are cooled by low-temperature refrigerant (7°C low-temperature water), and most of the styrene and water therein are condensed and enter the pre-pump oil-water separator 15 for oil-water separation. The water phase enters the condensate tank 11b, and then is sent to the condensate-flue gas vaporizer 4j through the condensate pump 9j for heating and vaporization to form superheated steam at 60-65°C, which is bubbled into the semi-lean liquid tank 13-11 and the lean liquid tank 13-10; the oil phase, i.e., styrene, is discharged into the intermediate oil tank 16 through the vacuum unloading valve 17 to realize the recovery of the styrene component.

[0156] 6) System heating

[0157] According to the system heat balance analysis, the media that need to be heated include the primary desorbed gas, the secondary desorbed gas, the rich liquid entering the flash kettle 13, and the aeration water vapor. The primary desorbed gas and the secondary desorbed gas need to be heated from about 100°C after the cooling wheel to 220°C, the rich liquid entering the flash kettle 13 needs to be heated from 20-30°C to 60-65°C, and the aeration water vapor entering the flash kettle 13 needs to be heated from condensed water at 20-30°C to 60-65°C.

[0158] ① The secondary desorbed gas and part of the primary desorbed gas are introduced into the incinerator 19 through the incinerator fan 1d for incineration, generating high-temperature flue gas of 850°C and low-temperature flue gas of 110-115°C.

[0159] ② Through the high-temperature flue gas exhaust 1e, high-temperature flue gas of 800-850℃ is drawn out from the high-temperature flue gas outlet of the incinerator 19 with a speed of 5500-6000Nm 3 / h, and is divided into two parts by the first-level high-temperature flue gas valve 20g and the second-level high-temperature flue gas valve 20h, and enters the first-level desorption gas heat exchanger 4a and the second-level desorption gas heat exchanger 4b respectively to exchange heat with the first-level desorption gas and the second-level desorption gas. The temperature of the desorption gas is increased from 100°C to 220°C, and the temperature of the high-temperature flue gas is reduced to 210-250°C;

[0160] ③ The high-temperature flue gas cooled to 210-250℃ is extracted by the high-temperature flue gas exhaust 1e, and is divided into three parts through the semi-lean liquid heating flue gas valve 20d, the condensed water vaporization flue gas valve 20e, and the rich liquid heating emergency valve 20n. One part enters the semi-lean liquid-flue gas heat exchanger 4k to heat the semi-lean liquid, one part enters the condensed water-flue gas vaporizer 4j, and the remaining part is introduced into the incinerator 19 through the incinerator fan 1d for circulation to dilute the concentrated gas entering the furnace.

[0161] ④ Through the low-temperature flue gas exhaust 1f, the low-temperature flue gas of 105-115℃ is drawn out from the low-temperature flue gas outlet of the incinerator 19 with a pressure of 13000-14000Nm 3 / h, and is divided into two parts through the regulation of the rich liquid heating flue gas valve 20b and the flue gas discharge emergency valve 20a. One part enters the rich liquid-flue gas heat exchanger 4e to exchange heat with the rich liquid, and the low-temperature flue gas temperature is cooled from 105-115℃ to 60-70℃; the remaining part is discharged from the chimney through the flue gas discharge emergency valve 20a to adjust the flow rate.

[0162] ⑤ The low-temperature flue gas with a temperature of 60-70°C exiting the rich liquid-flue gas heat exchanger 4e is adjusted through the flue gas circulation valve 20c and the external flue gas valve 20m to adjust the circulating flue gas volume entering the incinerator 19 and the external flue gas volume.

[0163] ⑥ The amount of flue gas discharged from the chimney is adjusted to be as small as possible through the external discharge emergency valve 20a, and the amount of the primary desorption gas introduced into the incinerator 19 is adjusted according to the amount of low-temperature flue gas discharged through the external discharge emergency valve 20a. When the amount of low-temperature flue gas discharged through the external discharge emergency valve 20a is large, the amount of the primary desorption gas introduced into the incinerator 19 is reduced until it is not adjusted to be discharged from the external discharge emergency valve 20a, and the amount of the primary desorption gas entering the absorption tower 7 is increased to increase the absorption amount of styrene.

[0164] 7) Non-condensable gas recovery and treatment

[0165] The pressure in the flash reactor is controlled at 4 kPa, and the amount of gas discharged by the vacuum pump is about 4000 m 3 / h, of which non-condensable gas 10-20% (based on 60m 3 / h), after being cooled to about 20℃ by the flash steam condenser for 4h, the water and most of the styrene components in the flash steam are condensed, and after leaving the vacuum pump, it enters the normal pressure state, and the volume of non-condensable gas is 2.11m 3 / h The remaining non-condensable gas has a high concentration of styrene, about 29g / Nm 3 The amount of styrene carried out by non-condensable gas is about 60g / h.

[0166] The styrene concentration in the non-condensable gas exceeds the lower limit of the styrene explosion concentration, and is promptly mixed with the concentrated gas out of the tower and enters the incinerator 19 for incineration and heat extraction.

[0167] 8) Diethyl phthalate is preferably used as the styrene absorbent

[0168] The absorbent used in the method of the present invention is a high-boiling point organic solvent having a boiling point higher than that of styrene by more than 100° C., preferably diethyl phthalate.

[0169] See also Figure 3 The Henry constant of the solution after diethyl phthalate absorbs styrene is: 23.04kg / (moL·kPa).

[0170] The process of the present 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 0.1kg / t-styrene. Compared with the distillation process, it saves more than 50% of energy consumption and reduces the recovery cost by more than 50%.

[0171] Winter: Winter temperature is low, and the concentration of styrene from the tail gas of the production line is low, 300-500mg / Nm 3 .

[0172] During winter operation, only the secondary wheel 3b is opened and the primary wheel 3a is closed, that is, the primary wheel air inlet valve 20p is closed and the secondary wheel air inlet valve 20q is opened. The styrene tail gas on the production line is collected and blown into the secondary wheel 3b for adsorption and purification under the suction action of the main fan 1a and then discharged. At the same time, the absorption and flash evaporation analysis units are shut down, and the rest of the operation process is the same as above.

Claims

1. A method for recycling styrene pollution components in waste gas from an artificial stone production line, characterized in that: The exhaust gas from the artificial stone production line enters the rotary unit for adsorption and concentration under the suction action of the fan, and the purified tail gas after adsorption is discharged. The concentrated gas after desorption enters the absorption tower and contacts with the lean liquid of absorbent in the tower in countercurrent, and the styrene component is absorbed. The concentrated gas at the top of the tower is defogged by the defogger and then led out, or sent to the incinerator, or mixed with the exhaust gas from the artificial stone production line and sent to the rotary unit; the rich liquid that absorbs the styrene component at the bottom of the absorption tower is heated and sent to the flash analysis unit, and the styrene component is analyzed and recovered, and the lean liquid after analysis returns to the absorption tower as the absorbent for cyclic spraying to absorb styrene.

2. The method for recycling styrene pollution components in waste gas from an artificial stone production line according to claim 1, characterized in that: The rotor unit comprises two stages of rotors connected in series, wherein the primary purified gas generated after adsorption by the primary rotor is further adsorbed by the secondary rotor to obtain purified tail gas for external discharge; the primary concentrated gas generated by the primary rotor is cooled to below 25°C and sent to the absorption tower for countercurrent contact with the absorbent lean liquid in the tower; the secondary concentrated gas generated by the secondary rotor is either sent to the incinerator, or part of it is mixed with the exhaust gas from the artificial stone production line and then sent to the primary rotor, and the rest is mixed with the primary concentrated gas and then sent to the absorption tower.

3. The method for recycling styrene pollution components in waste gas from an artificial stone production line according to claim 2, characterized in that: The primary concentrated gas generated after the primary wheel adsorption is divided into two streams, one stream is sent to the absorption tower, and the other stream is sent to the incinerator.

4. The method for recycling styrene pollution components in waste gas from an artificial stone production line according to any one of claims 1 to 3, characterized in that: The flash evaporation analysis unit comprises a flash evaporation kettle, which has at least two stages of flash evaporation chambers and a bottom liquid storage tank from top to bottom.

5. The method for recycling styrene pollution components in waste gas from an artificial stone production line as claimed in claim 4, characterized in that: The upper section of the flash kettle is a primary flash chamber, and the lower section is a secondary flash chamber. The bottom liquid storage tank is divided into a lean liquid tank and a semi-lean liquid tank by at least one overflow plate. A primary flash atomizer is arranged on the upper part of the primary flash chamber, and a primary flash guide plate is arranged on the bottom; a secondary flash atomizer is arranged on the upper part of the secondary flash chamber, and a secondary flash guide plate is arranged in a part of the lower part of the secondary flash chamber located above the semi-lean liquid tank, and the remaining area is communicated with 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 through an air stripping gas guide pipe, the semi-lean liquid tank is connected to the secondary flash atomizer through a semi-lean liquid-flue gas heat exchanger and a semi-lean liquid electric auxiliary heater, and the primary flash chamber is connected to the semi-lean liquid tank through a primary flash guide pipe. The rich liquid at the bottom of the absorption tower is heated to 60-65°C and then sent to the first-level flash atomizer of the first-level flash chamber of the flash kettle for spraying for flash evaporation; the semi-lean liquid after the first-level flash evaporation falls into the semi-lean liquid tank, and then is extracted and heated to 65-70°C and sent to the second-level flash atomizer of the second-level flash chamber for spraying for second-level flash evaporation, and the obtained lean liquid falls into the lean liquid tank and is then led out of the flash kettle and sent into the liquid holding column; the gas phase of the second-level flash chamber and the gas phase of the first-level flash chamber are led out of the flash kettle under negative pressure and sent to the flash steam condenser.

6. The method for recycling styrene pollution components in waste gas from an artificial stone production line as claimed in claim 5, characterized in that: The flash evaporation and analysis unit comprises a flash evaporation kettle and a rich liquid reflux washing tower, and the upper section of the primary flash evaporation chamber of the flash evaporation kettle is also provided with a reflux rich liquid atomizer; The rich liquid from the absorption tower is divided into two streams. The first stream of rich liquid is heated to 60-65°C and then sent to the first-stage flash atomizer of the flash kettle for spraying and analysis to recover the styrene component. The second stream of rich liquid is sent to the rich liquid reflux washing tower for heat exchange with the gas phase washing from the flash kettle; The rich liquid from the rich liquid reflux washing tower is also divided into two streams. The first stream is sent to the reflux rich liquid atomizer of the flash kettle for spraying and analyzing to recover the styrene component. The second stream is mixed with the first stream from the absorption tower, heated to 60-65°C, and then sent to the primary flash atomizer of the flash kettle for spraying. The gas phase out of the flash kettle is washed and heat-exchanged with the second stream of rich liquid from the absorption tower through the rich liquid reflux washing tower and then sent to the flash steam condenser.

7. The method for recycling styrene pollution components in waste gas from an artificial stone production line as claimed in claim 6, characterized in that: The first stream of rich liquid from the absorption tower is heat exchanged with the lean liquid from the holding liquid column, and then further heated to 60-65°C before being sent to the flash kettle.

8. The method for recycling styrene pollution components in waste gas from an artificial stone production line according to any one of claims 5 to 7, characterized in that: Inert gas components with a boiling point lower than styrene and insoluble in the absorbent are introduced into the lean liquid tank and the semi-lean liquid tank in the flash kettle to further strip the residual styrene components in the lean liquid and the semi-lean liquid. These inert gas components are water vapor, or a mixture of water vapor and nitrogen or carbon dioxide.

9. The method for recycling styrene pollution components in waste gas from an artificial stone production line according to claim 8, characterized in that: The stripping gas escaping from the semi-lean liquid tank is introduced into the primary flash chamber through the stripping gas guide pipe and the demister; the stripping gas escaping from the lean liquid tank directly enters the secondary flash chamber, and the gas phase in the primary flash chamber and the secondary flash chamber is drawn out of the flash kettle under the suction action of the vacuum pump.

10. The method for recycling styrene pollution components in waste gas from an artificial stone production line according to claim 8, characterized in that: The gas phase from the flash chamber is separated into condensate and non-condensable gas through a flash steam condenser, and the condensate is separated into styrene component and condensed water through a pre-pump oil-water separator. The separated condensed water is heated and vaporized by a condensate-flue gas vaporizer and then introduced into the lean liquid tank and semi-lean liquid tank in the flash kettle as water vapor to strip the styrene component in the lean liquid and semi-lean liquid, thereby realizing condensed water circulation.

11. The method for recycling styrene pollution components in waste gas from an artificial stone production line according to claim 10, characterized in that: The non-condensable gas separated by the flash steam condenser is pumped out by a vacuum pump and mixed with the tail gas from the demister tower.

12. The method for recycling styrene pollution components in waste gas from an artificial stone production line according to any one of claims 1 to 3, characterized in that: The high-temperature flue gas above 800°C drawn out from the incinerator is heat exchanged with the desorbed gas of the rotary unit through the desorbed gas heat exchanger to form a medium-temperature flue gas with a temperature of 230-250°C, which is then divided into three streams. The first stream is indirectly heat exchanged with the semi-lean liquid from the semi-lean liquid tank to form a low-temperature flue gas for external discharge, the second stream is indirectly heat exchanged with the condensed water sent to the flash kettle for stripping to vaporize the condensed water to form a low-temperature flue gas for external discharge, and the third stream is heat exchanged with the rich liquid from the absorption tower to form a low-temperature flue gas, which is circulated in the RTO incinerator by regulating the flow rate through the flue gas circulation valve, and the rest is discharged through the external exhaust flue gas valve.

13. The method for recycling styrene pollution components in waste gas from an artificial stone production line according to claim 12, characterized in that: The incinerator draws out low-temperature flue gas of 100-120°C and divides it into two streams. One stream is mixed with the third medium-temperature flue gas and then passes through a heat exchanger to heat the rich liquid from the absorption tower, and the other stream is discharged externally for emergency.

Images