Waste gas treatment system and method integrating heat recovery and pollutant treatment

Abstract

The invention discloses a heat recovery and pollutant treatment integrated waste gas treatment system and method.The system comprises a high-temperature rotary flue gas heat exchanger and a spraying device, a hot channel inlet of the high-temperature rotary flue gas heat exchanger is connected with a sizing waste gas pipeline with a control valve, and a hot channel outlet is connected with a smoke exhaust pipeline; room-temperature air is introduced into a cold channel of the high-temperature rotary flue gas heat exchanger, and heated hot air is discharged from an outlet of the cold channel; the spraying device is used for spraying a persulfate PMS solution into the smoke exhaust pipeline, and particulate matters, oil smoke and VOCs substances of circulating waste gas in the smoke exhaust pipeline are absorbed through sprayed PMS solution micro-droplets. Compared with a conventional spray tower, the spray tower has the advantages that the gas-liquid contact ratio is increased, most of oil substances can be oxidized, generation of sizing waste oil serving as hazardous waste is greatly reduced, and the spray tower has good engineering application economy.

Description

Technical Field

[0001] This invention relates to the field of industrial waste gas pollution control technology, specifically to a waste gas treatment system and method that integrates heat recovery and pollutant treatment. Background Technology

[0002] Setting is a crucial process in the textile dyeing and finishing industry. The setting process typically uses natural gas or steam for heating, and the temperature of the setting exhaust gas can reach 180-230℃. Setting machines account for over 40% of the total energy consumption in dyeing and finishing, with over 60% of this energy being heat emitted from the setting exhaust gas. Particulate matter, oil fumes, and volatile organic compounds (VOCs) emitted from setting exhaust gas are major contributors to waste gas emissions in the dyeing and finishing industry. For setting exhaust gas, Zhejiang and other regions have issued emission standards such as the "Emission Standard for Air Pollutants from Textile Dyeing and Finishing Industry" (DB33 / 926-2015), which sets strict emission limits for VOCs, oil fumes, and dust in the exhaust gas. Currently, the industry mainly uses a spray + electrostatic treatment method for this exhaust gas. The treated exhaust gas meets emission standards, and the waste oil collected after spray cooling is treated as hazardous waste. The problem with this method is that the residual heat in the exhaust gas is not effectively utilized, which is detrimental to the efficient treatment of pollutants by subsequent electrostatic processes. Furthermore, the emission of high-temperature exhaust gas represents a significant energy waste for the environment. Meanwhile, the waste oil collected after spraying is hazardous waste, resulting in high treatment costs for enterprises.

[0003] Existing technology 1 (an integrated system for waste heat recovery and electrostatic oil removal from dyeing and setting machine exhaust gas, CN201510297169.7) integrates cylindrical electrostatic dust and oil removal technology with indirect heat exchange technology into a single structural design. Its innovation lies in the use of an annular heat exchange tube with a built-in high-voltage electrode, allowing the exhaust gas to complete two processes simultaneously as it passes through the annular channel: first, indirect heat exchange with the fresh air in the central channel to recover heat; second, under the action of a high-voltage electric field, oil fume particles are charged and adsorbed onto the annular heat exchange surface. This structure solves the problem of heat exchangers being easily clogged by oil in traditional processes, because electrostatic force causes oil mist particles to deposit orderly on the heat exchange surface, rather than randomly blocking the channel. Simultaneously, the deposited oil can partially flow down and collect at high temperatures, facilitating recovery and cleaning. The patent's drawback is that integrating electrostatic dust and oil removal technology with indirect heat exchange technology allows the temperature of the setting exhaust gas to reach up to 150℃, severely affecting the efficiency of electrostatic work. Furthermore, oily substances are not easily treated in high-temperature environments.

[0004] Existing technology 2 (a method and apparatus for purifying exhaust gas and recovering waste heat from a stenter, CN201210024850.0) proposes a technology that couples spray condensation with a heat pump. High-temperature exhaust gas first enters a spray scrubbing tower, directly contacting the low-temperature spray liquid to achieve cooling, dust removal, and removal of some water-soluble pollutants. The innovation lies in the fact that after absorbing the waste heat from the exhaust gas, the spray liquid is introduced as a low-temperature heat source into a lithium bromide absorption heat pump. The heat pump "upgrades" the low-grade heat in the spray liquid into high-grade thermal energy, which is used to prepare the hot water or steam required for the process. This method achieves deep recovery of sensible heat and latent heat (heat of water vapor condensation) in the exhaust gas, while the spray scrubbing acts as a pretreatment, resulting in significant energy savings and purification effects. The patent has the following drawbacks: the actual sizing exhaust gas contains a high concentration of oil and particulate matter, and the wastewater after spraying has a high concentration of pollutants. If it is directly introduced into the lithium bromide absorption heat pump as a low-temperature heat source without treatment, it will affect the life of the heat pump. At the same time, if the waste heat of the exhaust gas is to be fully absorbed, a large amount of spray liquid is required, and the quality of the spray liquid obtained is low.

[0005] Existing technology 3 (Waste gas purification and waste heat recovery system for textile setting machines, CN201520331827.X) uses a combination of a rotary total heat exchanger (energy recovery wheel) and an electrostatic purifier. The waste gas first undergoes primary filtration, then passes through the rotary heat exchanger, transferring most of its sensible and latent heat to the fresh air. The cooled waste gas then enters the high-voltage electrostatic purifier to remove fine oil mist and particulate matter. Its process design prioritizes "heat exchange first, then deep purification." The advantages are that the waste gas temperature entering the electrostatic purifier is already lower, improving electrostatic collection efficiency and making equipment operation safer; simultaneously, it avoids oil contamination of the expensive rotary heat exchanger core, extending the lifespan of the core equipment. However, the disadvantages are that the waste gas, even after heat exchange, cannot reach the optimal temperature for electrostatic treatment (generally less than 50℃) when directly entering the electrostatic purifier, and the recovered oil is hazardous waste, resulting in high subsequent treatment costs.

[0006] Existing technology 4 (a waste gas treatment system for textile setting machines, CN201610138048.5) proposes a core technology of condensation recovery. The system uses multi-stage condensers to gradually reduce the waste gas temperature below the dew point, causing gaseous oil and water vapor to condense into liquid and be separated and recovered. Its innovation lies in the use of a multi-stage condensation approach, where components with different boiling points are recovered at different temperature ranges, improving the purity and value of the recovered oil. The recovered waste heat exists in the heated cooling water and can be used in other applications. This method thoroughly removes pollutants and achieves the recycling of waste oil resources. However, its disadvantages include high multi-stage condensation recovery costs, and while oily substances in the waste gas can be recovered through condensation, high-concentration particulate matter in the waste gas cannot be removed by condensation.

[0007] Existing technology 5 (a multi-stage purification and waste heat recovery device for stenter exhaust gas (CN201920879699.0)) emphasizes modular multi-stage treatment. The system sequentially includes: a cyclone dust collector (removing large fiber particles), a spray washing and cooling tower (cooling and removing some oil), a gas-to-gas plate heat exchanger (recovering medium-temperature sensible heat), and a low-temperature plasma purifier (degrading VOCs and odors). Its innovation lies in performing tiered treatment and energy recovery based on the properties of pollutants and temperature ranges, and introducing low-temperature plasma as the ultimate purification method, effectively solving the odor problem that is difficult to handle with traditional technologies, and achieving synergistic control of multiple pollutants. The disadvantages are that the treatment process is complex and costly. Most of the heat cannot be recovered after cyclone dust collection and spray washing, and the washed oil is hazardous waste, resulting in high subsequent treatment costs.

[0008] In summary, existing technologies for treating shaped waste gas and recovering heat generally face challenges such as high treatment costs, low heat recovery rates, and the risk of secondary pollution. Therefore, there is an urgent need to develop a novel waste gas treatment technology that integrates heat recovery and pollution control, offering high efficiency, convenience, and low processing costs. Summary of the Invention

[0009] In view of the above-mentioned technical problems existing in the prior art, the purpose of the present invention is to provide a waste gas treatment system and method that integrates heat recovery and pollutant treatment.

[0010] The technical solution adopted in this invention is as follows: A waste gas treatment system integrating heat recovery and pollutant treatment includes a high-temperature rotary flue gas heat exchanger and a spray device. The hot channel inlet of the high-temperature rotary flue gas heat exchanger is connected to a fixed waste gas pipeline with a control valve, and the hot channel outlet is connected to a flue gas pipeline. Room temperature air is introduced into the cold channel of the high-temperature rotary flue gas heat exchanger, and heated hot air is discharged from the cold channel outlet. The spraying device is used to spray persulfate PMS solution into the exhaust duct. The sprayed PMS solution microdroplets absorb particulate matter, fumes, and VOCs in the exhaust gas flowing in the exhaust duct.

[0011] Furthermore, the spraying device includes a nozzle, a delivery pump, and a PMS solution storage tank. The nozzle is installed inside the exhaust pipe. An outlet is provided at the bottom of the exhaust pipe. The outlet at the bottom of the exhaust pipe is connected to the inlet of the delivery pump via a pipeline through the PMS solution storage tank. The outlet of the delivery pump is connected to the spray inlet pipe, which then extends into the exhaust pipe and connects to the inlet of the nozzle.

[0012] Furthermore, the nozzle is located at the center of the exhaust duct, and the nozzle's spray port is positioned opposite to the flow direction of the flue gas in the exhaust duct, so that the PMS solution sprayed from the nozzle reacts with the flue gas in a counter-current flow.

[0013] Furthermore, the exhaust duct is made of corrosion-resistant material.

[0014] Furthermore, the inlet and outlet of the hot channel of the high-temperature rotary flue gas heat exchanger are respectively equipped with an inlet pressure sensor and an outlet pressure sensor. The inlet of the hot channel of the high-temperature rotary flue gas heat exchanger is also connected to a steam delivery system. The inlet pressure sensor and the outlet pressure sensor are connected to the steam delivery system and the control valve on the shaped waste gas pipeline through a PLC control system. When the pressure difference monitored by the inlet pressure sensor and the outlet pressure sensor exceeds the set value, the PLC control system provides feedback and adjusts to close the control valve on the shaped waste gas pipeline. At the same time, the steam delivery system is started to input high-temperature steam into the hot channel of the high-temperature rotary flue gas heat exchanger, so that the waste oil condensed and precipitated in the hot channel of the high-temperature rotary flue gas heat exchanger is dissolved by the steam and discharged in the form of oily wastewater.

[0015] The method of the exhaust gas treatment system integrating heat recovery and pollutant treatment involves introducing high-temperature sizing exhaust gas into the hot channel inlet of the high-temperature rotary flue gas heat exchanger, while simultaneously introducing room temperature air into the cold channel of the high-temperature rotary flue gas heat exchanger. The heating rotary chip of the high-temperature rotary flue gas heat exchanger rotates continuously to achieve heat exchange between the sizing exhaust gas and the air, and controlling the temperature of the sizing exhaust gas after heat exchange at 60-65℃. The heat-exchanged and shaped exhaust gas enters the flue gas duct, and at the same time, a persulfate PMS solution is sprayed into the flue gas duct through a spraying device. The exhaust gas and PMS solution react in countercurrent contact, and the temperature of the exhaust gas is used to thermally activate the PMS. The activation generates sulfate free radicals, which oxidize and degrade the oily substances absorbed by the wastewater, thereby achieving the purpose of dust removal.

[0016] Furthermore, the temperature of the styling exhaust gas introduced into the hot channel inlet of the high-temperature rotary flue gas heat exchanger is 150-200℃, and the temperature of the air discharged after heating is 110-140℃. The hot air after heat exchange is reused in the hot air utilization process of the styling machine.

[0017] Furthermore, the concentrations of oil fumes, particulate matter, and VOCs in the sizing exhaust gas are all below 100 mg / m³. 3 The following describes the application of the setting process in a setting machine. Due to variations in fabric type and operating temperature, the concentration of pollutants in the setting exhaust gas varies. Generally, the concentration of pollutants in the setting exhaust gas is between 40 and 50 mg / m³ for oily fumes. 3 The particulate matter concentration ranges from 60 to 70 mg / m³. 3 The concentration of VOCs produced ranges from 60 to 100 mg / m³. 3 between.

[0018] Furthermore, the concentration of the PMS solution is controlled at 5-15 mM, preferably 8-12 mM, and the volume ratio of waste gas to PMS solution is 500:1 to 2000:1.

[0019] Furthermore, the bottom of the exhaust pipe is provided with a liquid outlet, through which the PMS solution discharged is reused in the spraying device. When the concentration of the reused PMS solution is lower than 3-5 mM, the solution is replaced.

[0020] Furthermore, the inlet and outlet of the hot channel of the high-temperature rotary flue gas heat exchanger are respectively equipped with an inlet pressure sensor and an outlet pressure sensor. When the pressure difference between the inlet and outlet of the hot channel exceeds the set value, it indicates that waste oil blockage has occurred inside. At this time, the flow of sizing waste gas and air is stopped, and high-temperature water vapor is introduced into the hot channel so that the waste oil condensed and precipitated in the hot channel of the high-temperature rotary flue gas heat exchanger is dissolved by water vapor and discharged in the form of oily wastewater.

[0021] The core of this invention lies in "a high-efficiency heat exchange integrated dust removal + oxidation + cooling persulfate pipe spraying technology". The specific steps are as follows: Step 1: Heat exchange using a high-temperature rotary flue gas heat exchanger The working principle of a high-temperature rotary flue gas heat exchanger: When high-temperature exhaust gas passes through the exhaust duct of the heat exchanger, it heats the metal heat exchange plates of the rotary chip, reducing its own exhaust temperature (which can be below 65℃). The heated chip rotates to the other side, isolating the air duct, and the metal heat exchange plates on the chip transfer heat to the low-temperature inlet air. The low-temperature inlet air is then heated to a higher temperature and sent out of the heat exchanger (the temperature can reach 120-150℃). This process is repeated continuously as the chip rotates, achieving heat exchange between the airflows. Using this heat exchange equipment at the outlet of the stenter exhaust gas can recover the waste heat from the exhaust gas, and the hot air after heat exchange can be reused at the front or rear of the stenter. However, due to the high concentration of particulate matter and oil fumes in the stenter exhaust gas treatment, the waste oil condensed from the particulate matter and oily aerosols after the system cools down can cause blockage of the heat exchanger. The heat exchanger and pipes are difficult to clean, which can easily lead to fires and other safety accidents. When the pressure difference between the inlet and outlet of the hot channel of the high-temperature rotary flue gas heat exchanger is large, this application uses a PLC control system to regulate the steam delivery system to start operation, inputting high-temperature steam into the hot channel of the high-temperature rotary flue gas heat exchanger, so that the waste oil condensed and precipitated in the hot channel of the high-temperature rotary flue gas heat exchanger is dissolved by the steam and discharged in the form of oily wastewater.

[0022] Step 2: Spraying persulfate solution into the pipeline The exhaust gas after heat exchange is collected and discharged through a flue gas duct. A direct spray system using persulfate (PMS) solution is installed within the duct, which is made of corrosion-resistant material. The persulfate solution circulation rate is determined based on the exhaust gas flow rate, typically 500:1 to 2000:1 (i.e., per 500 to 2000 m³ / h of exhaust gas treated). 3 / h of exhaust gas, 1m³ required 3 The persulfate PMS solution is maintained at a concentration of 5-15 mM, preferably 8-12 mM. The solution is replaced when the concentration falls below 3-5 mM. This step primarily utilizes the temperature of the waste gas to thermally activate the PMS, generating sulfate free radicals (SO42-). ·- This system oxidizes and degrades oily substances absorbed by wastewater, while also removing dust. Compared to conventional spray towers, it increases the gas-liquid contact ratio and oxidizes most oily substances, significantly reducing the generation of solidified waste oil, a hazardous waste.

[0023] Compared with the prior art, the beneficial effects achieved by the present invention are: 1) High-efficiency heat exchange and pollutant removal: The system has a waste gas heat utilization rate of ≥70%, and saves ≥15% of the natural gas consumption of a single stenter; the removal rate of particulate matter and oily substances is >95%, the amount of stenter waste oil generated can be reduced by more than 75%, and the waste gas can meet the emission standards; the waste gas treatment cost is reduced by more than 60% compared with the existing spray + electrostatic technology.

[0024] 2) Economic efficiency and environmental friendliness: The treatment-free technology is simple, convenient, and low-cost. Preliminary economic analysis shows that compared with the operating costs of existing stenters (including heat source costs and waste gas treatment costs), it can reduce costs by more than 25%, demonstrating good economic efficiency in engineering applications. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of a waste gas treatment system that integrates heat recovery and pollutant treatment according to this application. Detailed Implementation

[0026] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0027] Example: Comparison Figure 1 A waste gas treatment system integrating heat recovery and pollutant treatment includes a high-temperature rotary flue gas heat exchanger 1 and a spray device. The hot channel inlet of the high-temperature rotary flue gas heat exchanger 1 is connected to a fixed waste gas pipeline with a control valve, and the hot channel outlet is connected to a flue gas exhaust pipeline 2. Room temperature air is introduced into the cold channel of the high-temperature rotary flue gas heat exchanger, and heated air is discharged from the cold channel outlet. The spray device is used to spray a persulfate PMS solution into the flue gas exhaust pipeline 2. The micro-droplets of the sprayed PMS solution absorb particulate matter, oil fumes, and VOCs in the waste gas flowing in the flue gas exhaust pipeline 2.

[0028] The spraying device includes a nozzle 3, a delivery pump 4, and a PMS solution storage tank 5. The nozzle 3 is installed inside the exhaust pipe 2. The exhaust pipe 2 has a liquid outlet at the bottom. The liquid outlet at the bottom of the exhaust pipe 2 is connected to the inlet of the delivery pump 4 through the PMS solution storage tank 5 via a pipeline. The outlet of the delivery pump 4 is connected to the spraying liquid inlet pipe, which then passes through the exhaust pipe 2 and connects to the inlet of the nozzle 3.

[0029] The nozzle 3 is located at the center of the exhaust duct 2, and the spray nozzle 3 is positioned opposite to the flow direction of the flue gas in the exhaust duct 2, so that the PMS solution sprayed from the nozzle 3 reacts with the flue gas in a countercurrent flow.

[0030] The processing method of the system of the present invention is as follows: high-temperature sizing waste gas is introduced into the hot channel inlet of the high-temperature rotary flue gas heat exchanger 1, while room temperature air is introduced into the cold channel inlet of the high-temperature rotary flue gas heat exchanger 1. The heating rotary chip of the high-temperature rotary flue gas heat exchanger 1 rotates continuously to achieve heat exchange between the sizing waste gas and the air, and the temperature of the sizing waste gas after heat exchange is controlled at 60-65℃. The sizing waste gas after heat exchange enters the exhaust pipe, and at the same time, persulfate PMS solution is sprayed into the exhaust pipe through a spraying device. The waste gas and PMS solution react countercurrently, and the temperature of the waste gas is used to thermally activate the PMS. The activation generates sulfate free radicals, which oxidize and degrade the oily substances absorbed by the wastewater, and at the same time achieve the purpose of dust removal.

[0031] The PMS solution discharged from the bottom outlet of the exhaust duct is reused in the spray system. When the concentration of the reused PMS solution is lower than 3-5 mM, the solution is replaced. The temperature of the styling exhaust gas introduced into the hot channel inlet of the high-temperature rotary flue gas heat exchanger 1 is 150-200℃. After being heated, the temperature of the discharged air is 110-140℃. The hot air after heat exchange is reused in the hot air utilization process of the styling machine.

[0032] Example 1: Take a setting machine from a printing and dyeing enterprise. The concentration of pollutants generated in the setting exhaust gas produced by the setting process of the setting machine is: oil fume concentration approximately 45±2 mg / m³. 3 The particulate matter concentration is approximately 65±5 mg / m³. 3VOCs concentration is approximately 80±10 mg / m³ 3 The volume of the styrofoam exhaust gas is 14,500 m³. 3 The high-temperature rotary flue gas heat exchanger proposed in this invention is used for heat exchange at a rate of 192°C. The temperature of the exhaust gas inlet is 146°C, and the temperature of the fresh air obtained after heat exchange is 60°C. A spray nozzle in the center of the exhaust duct sprays a persulfate PMS solution. The sprayed PMS solution droplets come into countercurrent contact with the exhaust gas in the exhaust duct. The initial concentration of the PMS solution is 10 mM. The PMS solution sprayed in the exhaust duct is discharged through the outlet at the bottom of the exhaust duct into a PMS solution storage tank. It is then pumped back to the spray nozzle for spraying. The circulation rate of the PMS solution is 2 m³ / h. 3 After spraying for 40 hours, the exhaust gas temperature remained below 50℃, and the experimental results still showed that the pollutant concentration of particulate matter was ≤10 mg / m³. 3 Oil fume ≤10 mg / m³ 3 VOCs ≤15 mg / m³ 3 It meets relevant national emission standards. The PMS solution is replaced when its concentration drops below 5 mM. The concentration of petroleum hydrocarbons in the recycled solution is below 100 mg / L. After oil separation, the solution is sent to a wastewater treatment plant for centralized treatment, significantly reducing the amount of solid waste oil generated as hazardous waste. Compared to existing spray + electrostatic technology, the cost of waste gas treatment is reduced by more than 60%, saving 15-20% of natural gas used as a heat source.

[0033] The contents described in this specification are merely an enumeration of the implementation forms of the inventive concept, and the scope of protection of this invention should not be regarded as limited to the specific forms described in the embodiments.

Claims

1. A waste gas treatment system integrating heat recovery and pollutant treatment, characterized in that, It includes a high-temperature rotary flue gas heat exchanger (1) and a spray device. The hot channel inlet of the high-temperature rotary flue gas heat exchanger (1) is connected to a fixed exhaust gas pipe with a control valve, and the hot channel outlet is connected to a flue gas pipe (2). The cold channel of the high-temperature rotary flue gas heat exchanger is vented with room temperature air, and the cold channel outlet is vented with heated hot air. The spraying device is used to spray persulfate PMS solution into the exhaust pipe (2). The sprayed PMS solution microdroplets absorb particulate matter, oil fumes, and VOCs in the exhaust gas flowing in the exhaust pipe (2).

2. The waste gas treatment system integrating heat recovery and pollutant treatment as described in claim 1, characterized in that, The spraying device includes a nozzle (3), a delivery pump (4), and a PMS solution storage tank (5). The nozzle (3) is installed inside the exhaust pipe (2). The exhaust pipe (2) has an outlet at the bottom. The outlet at the bottom of the exhaust pipe (2) is connected to the inlet of the delivery pump (4) through the PMS solution storage tank (5) by a pipeline. The outlet of the delivery pump (4) is connected to the spray inlet pipe. The spray inlet pipe then passes through the exhaust pipe (2) and connects to the inlet of the nozzle (3).

3. The waste gas treatment system integrating heat recovery and pollutant treatment as described in claim 2, characterized in that, The nozzle (3) is located at the center of the exhaust pipe (2), and the nozzle (3) is positioned opposite to the flow direction of the flue gas in the exhaust pipe (2), so that the PMS solution sprayed by the nozzle (3) reacts with the flue gas in a countercurrent flow.

4. The waste gas treatment system integrating heat recovery and pollutant treatment as described in claim 1, characterized in that, The exhaust pipe (2) is made of corrosion-resistant material.

5. The waste gas treatment system integrating heat recovery and pollutant treatment as described in claim 1, characterized in that, The inlet and outlet of the hot channel of the high-temperature rotary flue gas heat exchanger (1) are respectively equipped with an inlet pressure sensor and an outlet pressure sensor. The inlet of the hot channel of the high-temperature rotary flue gas heat exchanger (1) is also connected to a steam delivery system. The inlet pressure sensor and the outlet pressure sensor are connected to the steam delivery system and the control valve on the shaped waste gas pipeline through the PLC control system. When the pressure difference monitored by the inlet pressure sensor and the outlet pressure sensor exceeds the set value, the control valve on the shaped waste gas pipeline is closed by the feedback and adjustment through the PLC control system. At the same time, the steam delivery system is started to input high-temperature steam into the hot channel of the high-temperature rotary flue gas heat exchanger (1), so that the waste oil condensed and precipitated in the hot channel of the high-temperature rotary flue gas heat exchanger is dissolved by the steam and discharged in the form of oily wastewater.

6. The method for a waste gas treatment system integrating heat recovery and pollutant treatment as described in claim 1, characterized in that, High-temperature sizing exhaust gas is introduced into the hot channel inlet of the high-temperature rotary flue gas heat exchanger (1), while room temperature air is introduced into the cold channel of the high-temperature rotary flue gas heat exchanger (1). The heating rotary chip of the high-temperature rotary flue gas heat exchanger (1) rotates continuously to achieve heat exchange between the sizing exhaust gas and the air, and control the temperature of the sizing exhaust gas after heat exchange at 60-65℃. The heat-exchanged and shaped exhaust gas enters the flue gas duct, and at the same time, a persulfate PMS solution is sprayed into the flue gas duct through a spraying device. The exhaust gas and the PMS solution react in a countercurrent manner, and the temperature of the exhaust gas is used to thermally activate the PMS. The activation generates sulfate free radicals, which oxidize and degrade the oily substances absorbed by the wastewater, thereby achieving the purpose of dust removal.

7. The method as described in claim 6, characterized in that, The concentrations of oil fumes, particulate matter, and VOCs in the sizing exhaust gas are all above 100 mg / m³. 3 The temperature of the styling exhaust gas introduced into the hot channel of the high-temperature rotary flue gas heat exchanger (1) is 150-200℃, and the temperature of the air discharged after being heated is 110-140℃. The hot air after heat exchange is reused in the hot air utilization process of the styling machine.

8. The method as described in claim 6, characterized in that, The concentration of the PMS solution is controlled at 5-15 mM, preferably 8-12 mM, and the volume ratio of waste gas to PMS solution is 500:1 to 2000:

1.

9. The method as described in claim 6, characterized in that, The bottom of the exhaust pipe is provided with a liquid outlet. The PMS solution discharged through this outlet is reused in the spraying device. When the concentration of the reused PMS solution is lower than 3-5 mM, the solution is replaced.

10. The method as described in claim 6, characterized in that, The inlet and outlet of the hot channel of the high-temperature rotary flue gas heat exchanger (1) are respectively equipped with an inlet pressure sensor and an outlet pressure sensor. When the pressure difference between the inlet and outlet of the hot channel exceeds the set value, it indicates that waste oil blockage has occurred inside. At this time, the flow of sizing waste gas and air is stopped, and high-temperature water vapor is introduced into the hot channel so that the waste oil condensed and precipitated in the hot channel of the high-temperature rotary flue gas heat exchanger is dissolved by water vapor and discharged in the form of oily wastewater.

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