Long-acting management method and equipment for cooking oil fume

Abstract

The application discloses a long-term management method and equipment for kitchen oil fume. The method is based on the principle of "similar solubility", and high-boiling-point organic matters such as vegetable oil or kitchen waste oil are innovatively used as detergents to efficiently purify the oil fume. The oil gas in the oil fume is dissolved and absorbed, and the particulate matters are captured and enriched on the surface of the detergent, and then are automatically discharged through overflow and can be disposed of in a resourceful manner together with kitchen garbage without secondary pollution; the purified gas is discharged after high-efficiency demisting. The equipment for realizing the method adopts a uniquely designed symmetrical gradient air distribution pipe network, ensures sufficient contact between gas and liquid, and completely solves the industry problems of oil adhesion, blockage and efficiency decay in the traditional technology. The application has the advantages of stable operation, simple maintenance, long-term maintenance-free efficient purification, low investment and operation cost, and suitability for various catering places.

Description

Technical Field

[0001] This invention relates to the field of environmental protection and air pollution control technology, specifically to a long-term treatment method and equipment for restaurant fumes. Background Technology

[0002] Restaurant fumes are complex, containing not only particulate matter (PM2.5 / PM10), but also various volatile organic compounds (VOCs) and odorous substances, posing a threat to human health and the atmospheric environment.

[0003] Currently, mainstream catering fume purification technologies mainly include mechanical, electrostatic, wet scrubbing, photocatalytic oxidation, activated carbon adsorption, and their combinations. However, all of them have certain shortcomings and are difficult to achieve long-term, stable, and pollution-free treatment effects. Specifically: (1) Mechanical purification method: This method uses physical mechanisms such as inertial collision, sieving, or centrifugal force to separate larger oil droplets in cooking fumes. The most common method is to pass the cooking fumes through a filter made of metal or composite materials. Large oil droplets are intercepted and adsorbed, and then flow into the oil collection box due to gravity. Cyclone demisters are also used, which make the cooking fume airflow rotate at high speed and use centrifugal force to throw the denser oil droplets against the wall and collect them. This type of technology has the advantage of simple structure, but it can only remove larger oil droplets. It has extremely low removal efficiency for fine particulate matter and VOCs, and the filter needs to be cleaned or replaced frequently, resulting in high maintenance costs.

[0004] (2) Electrostatic deposition method: This method uses a high-voltage electrostatic field to charge oil fume particles. The charged particles move towards the dust collection plate and are captured under the action of the electric field force. It is usually divided into an ionization zone (corona discharge) and a dust collection zone. It can efficiently remove particulate matter, with high removal efficiency for micron and submicron particles (up to 90% or more). It also has a wide airflow channel, low system pressure drop, and relatively low fan energy consumption. However, its core ionization zone and dust collection zone are easily wrapped by viscous oil mist, which leads to a rapid weakening or even failure of the electric field (i.e., "corona sealing" and "dust collection plate adhesion"), a sharp decline in purification efficiency, and the need for frequent and cumbersome cleaning and maintenance. It also has poor long-term operational stability.

[0005] (3) Traditional wet scrubbing usually uses water or chemical reagents as scrubbing liquid, which fully contacts the oily exhaust gas and transfers pollutants (especially water-soluble substances) into the liquid through absorption, dissolution and collision. Spray towers, Venturi scrubbers, water-cooled fume hoods, etc. are used. It has a certain effect on particulate matter, some water-soluble VOCs and odors, but it will produce emulsified oily wastewater with complex composition. Additional sewage treatment facilities are required. Otherwise, it will cause serious secondary pollution of water bodies. In essence, it is the transfer of air pollution to water pollution.

[0006] (4) Adsorption method: By utilizing the huge specific surface area of porous solid adsorbents (such as activated carbon and activated carbon fibers), gaseous pollutants (VOCs, odors) in cooking fumes can be adsorbed on their surfaces. However, its porous structure is extremely easy to be blocked by particulate matters in cooking fumes and wrapped by oil mists, resulting in rapid inactivation, frequent replacement, high operating costs, and the generation of a large amount of waste adsorbent garbage.

[0007] Given the limitations of the above single technologies, combined processes have emerged. Typical combined processes include "cooking range + smoke hood / mechanical filtration (pretreatment) + electrostatic purifier (core treatment) + adsorption / photocatalysis / wet scrubbing (deep treatment)", "electrostatic + activated carbon", "electrostatic + photocatalysis", "mechanical + electrostatic + wet", etc. However, such combinations are merely the superposition and compromise of technical defects and do not fundamentally solve the problems: the electrode adhesion and efficiency attenuation problems of the electrostatic unit still exist; the problem of wastewater disposal generated by the wet unit remains unresolved; the blockage and rapid failure of the adsorption unit are still pain points. Therefore, combined processes often lead to more complex systems, higher investment and maintenance costs, but the long-term operation stability and secondary pollution problems have not been fundamentally solved.

[0008] In summary, the existing cooking fume purification technologies generally face two major industry problems: First, the "long-term effectiveness" is insufficient: Due to the inherent adhesion characteristics of cooking fumes, the performance of the core purification components (such as electrostatic electrodes and adsorption materials) decays rapidly, and it is impossible to maintain long-term stable and efficient purification. Second, the "secondary pollution" is serious: The purification process generates wastewater and solid waste (such as waste activated carbon) that require special treatment, increasing the difficulty, cost, and environmental risks of end-of-treatment. Summary of the Invention

[0009] To address the above technical problems existing in the prior art, the present invention provides a long-term treatment method and equipment for cooking fumes. The method uses a high-boiling organic matter detergent to wash cooking fumes. The oil and gas in the cooking fumes enter the detergent and become part of the detergent; the particulate matters in the cooking fumes are captured by the detergent and enriched on the upper surface of the detergent. As the volume increases, part of the detergent leaves the washer together and is disposed of together with kitchen waste; the purified flue gas is discharged, thereby avoiding the adhesion and blockage of oil stains to the purification system in principle and enabling the resource-based disposal of waste without secondary pollution. The equipment配套 with the method has a simple structure, stable operation, and convenient maintenance, and can maintain high purification efficiency for a long time.

[0010] To achieve the above object, the present invention adopts the following technical solutions: A long-term treatment method for cooking fumes, comprising the following steps: S1. Providing detergent: A high-boiling-point organic compound is introduced into the washing equipment as a detergent, wherein the high-boiling-point organic compound is at least one of vegetable oil or waste cooking oil. S2. Oil fume washing: The cooking oil fume exhaust gas is passed into the detergent, so that the oil and gas in the oil fume dissolve into the detergent, and at the same time the particulate matter in the oil fume is captured by the detergent. S3. Pollutant enrichment and separation: The captured particulate matter is enriched on the upper surface of the detergent due to its oleophilic and hydrophobic properties. S4. Waste liquid discharge and disposal: The detergent that has been enriched with particulate matter and oil gas in step S3 is discharged as waste liquid through an overflow method and is disposed of together with kitchen waste for resource recovery. S5. Flue gas emission: The clean flue gas, after being washed and purified, is directly discharged into the air after being separated from the detergent.

[0011] An apparatus for implementing the above method is an integrated scrubber, comprising a detergent chamber, a flue gas network, an oil mist separator, an induced draft fan, an overflow pipe, and an oil fume collection tank. The detergent chamber is used to contain high-boiling-point organic detergent. The flue gas network consists of a main inlet pipe, branch inlet pipes, and a distribution pipe. The end of the distribution pipe is open and immersed in the detergent in the detergent chamber to disperse the oil fume exhaust gas into fine bubbles, increasing the gas-liquid contact area. The oil mist separator is located above the detergent chamber, and its inlet is connected to the purified gas outlet at the top of the detergent chamber. The oil mist separator is used to separate detergent droplets entrained in the purified flue gas. The induced draft fan is connected to the outlet of the oil mist separator to provide system power and guide the flow of flue gas. The overflow pipe is located at the upper liquid surface of the detergent in the detergent chamber, and its outlet extends into the oil fume collection tank. The overflow pipe is used to automatically discharge the detergent that has increased in volume due to dissolving oil and capturing particulate matter, and guide it into the oil fume collection tank.

[0012] Furthermore, the integrated washer is equipped with a support at the bottom, with a detergent inlet pipe connected to the middle of the detergent compartment and a detergent underflow pipe connected to the bottom.

[0013] Furthermore, the intake branch pipes are symmetrically distributed along the centerline of the detergent compartment cross-section, with the middle intake branch pipe being the highest and gradually decreasing in position towards the sides. This unique design ensures uniform distribution of flue gas across the detergent cross-section, avoids airflow short-circuiting, and significantly improves mass transfer efficiency.

[0014] Furthermore, the lower part of the oil mist separator is equipped with a detergent return pipe, which returns the captured detergent to the detergent tank and immerses it below the liquid surface to prevent gas short circuit and realize the internal circulation of detergent.

[0015] Furthermore, the outlet gas velocity at the end of the air distribution pipe is 0.2 m / s to 3 m / s, and the immersion depth of the outlet in the detergent is 100 mm to 500 mm. This parameter range is the optimal range verified by numerous experiments, ensuring sufficient bubble refinement and residence time, while achieving the best balance between energy consumption and purification efficiency.

[0016] Furthermore, the depth to which the end of the detergent return pipe is immersed in the detergent is not less than 50 mm, preferably 50 mm to 100 mm.

[0017] Furthermore, the overflow pipe outlet should be immersed in the detergent in the fume collection tank to a depth of not less than 30 mm, preferably 30 mm to 80 mm, to ensure an effective liquid seal.

[0018] Furthermore, the oil mist separator is a hydrocyclone demister or an inertial demister.

[0019] The beneficial effects of this invention are as follows: (1) This invention abandons the traditional approach of “interception, adsorption and electrostatic capture”. Based on the fact that oil fume originates from edible oil and its main components are the same as those of edible oil and catering waste oil, it uses the principle of like dissolves like to purify it efficiently. The two are completely miscible and form a uniform and stable phase. This can effectively avoid the problems of traditional electrostatic precipitators and adsorption purification technologies being easily adhered to and fail due to oil fume adhesion and regeneration. It can ensure the purification effect for a long time.

[0020] (2) The symmetrical gradient gas distribution design of the flue gas pipeline in the device of the present invention, combined with the optimization and limitation of key operating parameters (such as gas velocity in the gas distribution pipe and immersion depth), ensures efficient and uniform contact between the gas and liquid phases, thereby achieving a purification efficiency far exceeding that of the traditional wet scrubbing method. The device has a simple structure, is easy to operate and maintain, has high purification efficiency and low investment, and is suitable for deep treatment of oil fume in catering enterprises of all sizes.

[0021] (3) The vegetable oil and waste cooking oil used in this invention are non-toxic, harmless, and have good stability, and will not bring additional burden to the application system. Organic matter such as oil mist in the fume oil can be completely dissolved in it and become part of the fume detergent. The particulate matter in the fume has oleophilic and hydrophobic properties, which can be efficiently captured by the detergent. Because these particulate matter has a large specific surface area, it will float fully on the surface of the detergent, making it easy to separate from the detergent. The mixture of fume particulate matter and detergent collected in the second stage still has similar main components to the oil dust mixture collected by fume hoods, etc., and can be incorporated into kitchen waste for resource utilization. The whole process does not produce secondary pollutants such as wastewater and waste activated carbon that require special treatment, thus achieving a unity of environmental and economic benefits. Attached Figure Description

[0022] Figure 1The diagram shows the equipment of the present invention. In the diagram, 1 is the detergent compartment, 2 is the main air inlet pipe, 3 is the branch air inlet pipe, 4 is the air distribution pipe, 5 is the overflow pipe, 6 is the detergent inlet pipe, 7 is the detergent underflow pipe, 8 is the underflow pipe of the fume collection tank, 9 is the manhole, 10 is the purified air outlet, 11 is the oil mist separator, 12 is the exhaust fan, 13 is the support, 14 is the detergent return pipe, and 15 is the fume collection tank. Detailed Implementation

[0023] The present invention will be further described below with reference to specific embodiments, but the present invention is not limited thereto.

[0024] like Figure 1 As shown, the long-term treatment equipment for catering fumes of the present invention is an integrated scrubber. The bottom of the integrated scrubber is provided with a support 13 and a manhole 9. The "manhole" refers to an opening made on the shell of the equipment (such as a tank, tower, or silo) for personnel to enter and exit the equipment for installation, maintenance, cleaning, inspection and other operations. The integrated scrubber includes a detergent compartment 1 (with a detergent inlet pipe 6 connected to the middle and a detergent underflow pipe 7 connected to the bottom), a flue gas network, an oil mist separator 11, an exhaust fan 12, an overflow pipe 5, and an oil fume collection tank 15. The flue gas network consists of a main intake pipe 2, branch intake pipes 3, and a distribution pipe 4. One end of the main intake pipe 2 is connected to the flue gas, and the other end is connected to the branch intake pipe 3. The branch intake pipe 3 is connected to the distribution pipe 4. The branch intake pipes 3 are symmetrically distributed along the center line of the detergent compartment 1, with the middle branch intake pipe being the highest and the positions gradually decreasing towards the sides. The end of the distribution pipe 4 is open and immersed in the detergent in the detergent compartment. The oil mist separator 11 is located at the top of the detergent compartment 1, separating oil mist... The air inlet of the separator 11 is connected to the purified air outlet 10 at the top of the detergent tank 1. The oil mist separator 11 is used to separate the detergent droplets entrained in the purified flue gas. The lower part of the oil mist separator 11 is provided with a detergent return pipe 14 to return the captured detergent to the detergent tank 1 and immerse it below the liquid surface. The exhaust fan 12 is connected to the air outlet of the oil mist separator 11 to provide system power and guide the flow of flue gas. The overflow pipe 5 is set at the upper liquid surface of the detergent in the detergent tank 1. The outlet of the overflow pipe 5 extends into the oil fume collection tank 15. The overflow pipe 5 is used to automatically discharge the detergent that has increased in volume due to the dissolution of oil and gas and the capture of particulate matter, and guide it into the oil fume collection tank 15, and periodically discharge it through the bottom flow pipe 8 of the oil fume collection tank.

[0025] Its workflow is as follows: First, a selected high-boiling-point organic detergent (such as vegetable oil) is injected into the detergent tank 1 through the detergent inlet pipe 6 to the predetermined liquid level. Under the suction of the induced draft fan 12, the kitchen exhaust gas enters through the main intake pipe 2 and is distributed to each distribution pipe 4 via the intake branch pipe 3. The outlet at the end of the distribution pipe 4 is immersed in the detergent, releasing the exhaust gas in the form of fine bubbles. During this process, VOCs in the fumes are dissolved by the detergent, and particulate matter is captured by the liquid droplets and accumulated on the liquid surface.

[0026] The pre-purified flue gas rises and enters the oil mist separator 11 through the purified gas outlet 10, where it separates off the detergent droplets. The clean gas after separation is discharged into the atmosphere by the induced draft fan 12. The separated detergent is returned to the detergent tank 1 through the detergent return pipe 14, achieving recycling.

[0027] As the purification process proceeds, the detergent increases in volume due to dissolving oil fumes and carrying particulate matter, causing the liquid level to rise. When the liquid level exceeds the inlet of the overflow pipe 5, the upper layer of detergent, enriched with pollutants, automatically overflows into the fume collection tank 15 for temporary storage. It can be periodically discharged through the underflow pipe 8 of the fume collection tank for disposal together with kitchen waste. This design achieves continuous and automatic waste discharge and continuous and stable operation of the system.

[0028] Example 1

[0029] A school cafeteria has an exhaust volume of 2600 cubic meters per hour. The detergent compartment has a diameter of 1.6 meters and uses a hydrocyclone demister with an inlet velocity of 25 meters per second. Soybean oil is used as the detergent. The outlet immersion depth of the air distribution pipe is 200 millimeters, and the outlet air velocity is controlled at 1 meter per second. The oil mist separator 11 also uses a hydrocyclone demister with an inlet velocity of 25 meters per second. Testing showed that the oil fume concentration in the purified gas decreased to 3.6 mg / m³, demonstrating excellent purification performance. The average inlet concentration was 122 mg / m³, and the purification efficiency was 97%.

[0030] Example 2

[0031] A restaurant has an exhaust volume of 2200 cubic meters per hour. The equipment specifications are the same as in Example 1, and rapeseed oil is used as the detergent. The immersion depth of the air distribution pipe outlet is adjusted to 300 mm, the outlet air velocity is 0.86 m / s, and the inlet air velocity of the cyclone demister is 21 m / s. Testing showed that the oil fume concentration in the purified gas was 4.7 mg / m³. The average inlet concentration was 61 mg / m³, and the purification efficiency was 92.3%.

[0032] Example 3

[0033] Under the same conditions as in Example 2, pre-treated waste cooking oil was used as the detergent to verify resource recycling. The purified oil fume concentration was 12.6 mg / m³, slightly higher than that of new oil, but still met emission requirements, demonstrating the resource utilization of waste oil and proving the dual environmental and economic value of this invention. The average inlet concentration was 135 mg / m³, with a purification efficiency of 90.7%.

[0034] Example 4

[0035] To verify the long-term treatment capability of the present invention, a 30-day continuous operation test was conducted in the kitchen of a large commercial complex.

[0036] The processing air volume is 5000 cubic meters / hour, the detergent compartment diameter is 2.0 meters, soybean oil is selected as the detergent, the air velocity at the outlet of the air distribution pipe is controlled at 1.2 m / s, and the immersion depth is 250 mm.

[0037] Monitoring indicator: Oil fume concentration at the outlet (mg / m³), sampled and tested at fixed times every day.

[0038] The experimental results showed that no downtime for cleaning or internal maintenance was performed during the entire 30-day test period. Only on the 17th day, approximately 45 liters of enriched liquid were discharged through the overflow pipe (disposed of together with food waste), and an equal amount of fresh soybean oil was added. The entire process was completed by restaurant staff without the need for professional technicians.

[0039] Comparative Example 1

[0040] The processing air volume is 2600 cubic meters per hour, which is the same as in Embodiment 1 of the present invention.

[0041] The traditional electrostatic deposition method is adopted, specifically using high-voltage electrostatic purification equipment to treat catering fumes, including an ionization zone and a dust collection zone. The initial purification efficiency is relatively high, about 90%.

[0042] Experimental results showed that the oil fume concentration dropped below 5 mg / m³ in the initial stage of operation. However, after 7 days of continuous operation, due to oil adhesion to the electrodes, "corona sealing" and "dust collection plate adhesion" occurred, resulting in a decrease in purification efficiency to over 60% and an increase in oil fume concentration to 15 mg / m³. Weekly shutdown for electrode cleaning was required, leading to high maintenance costs, and the cleaning wastewater contained oil and required special treatment.

[0043] Comparative Example 2

[0044] The processing air volume is 2600 cubic meters per hour, which is the same as in Embodiment 1 of the present invention.

[0045] The traditional wet scrubbing method (water-based scrubbing) is adopted, which uses tap water as a detergent to wash and purify the oil fumes in a spray tower.

[0046] Experimental results showed that the concentration of oily fumes after purification was approximately 12 mg / m³, but the detergent rapidly emulsified, forming oily wastewater, requiring supporting wastewater treatment facilities. After 3 days of operation, the detergent developed a foul odor and needed to be replaced, causing secondary pollution (and high wastewater treatment costs).

[0047] Comparative Example 3

[0048] The processing air volume is 2600 cubic meters per hour, which is the same as in Embodiment 1 of the present invention.

[0049] The activated carbon adsorption method is adopted, specifically the activated carbon adsorption bed is used to treat oil fumes as a deep purification unit, with an activated carbon filling amount of 50 kg.

[0050] Experimental results show that the initial purification efficiency is high, reducing the oil fume concentration to 4 mg / m³. However, after 24 hours of operation, the activated carbon becomes deactivated due to oil mist blockage, and the purification efficiency drops below 50%. Frequent replacement of the activated carbon (weekly replacement) is required, resulting in high operating costs and the generation of a large amount of hazardous waste.

[0051] Comparative Example 4

[0052] The processing air volume is 2600 cubic meters per hour, which is the same as in Embodiment 1 of the present invention.

[0053] The combined process (electrostatic + wet washing) is adopted, specifically the "electrostatic purification + water washing" combined process, with the electrostatic unit connected to the water washing tower, which is commonly found in commercial fume purification systems.

[0054] Experimental results showed that the initial purification effect was good, with the oil fume concentration reduced to 6 mg / m³. However, after 10 days of operation, the efficiency of the electrostatic unit decreased, and the water washing unit produced emulsified wastewater. The system is complex, requires frequent maintenance (comprehensive cleaning every month), has high overall costs, and the wastewater treatment problem remains unresolved.

Claims

1. A long-term method for treating restaurant fumes, characterized in that, Includes the following steps: S1. Provide detergent: Fill the integrated scrubber with a high-boiling-point organic compound as detergent, wherein the high-boiling-point organic compound is at least one of vegetable oil or waste cooking oil. S2. Fume Washing: The kitchen exhaust gas is passed into the detergent, which dissolves the oil and gas in the fume into the detergent and captures the particulate matter in the fume. The integrated scrubber has a symmetrical gradient air distribution network. The air inlet branches are symmetrically distributed along the center line of the detergent compartment, with the middle air inlet branch being the highest and the position gradually decreasing towards the sides. The end of the air distribution pipe is open and immersed in the detergent. The outlet gas velocity is 0.2m / s to 3m / s and the immersion depth is 100 mm to 500 mm. S3. Pollutant enrichment and separation: The captured particulate matter is enriched on the upper surface of the detergent due to its oleophilic and hydrophobic properties. S4. Waste liquid discharge and disposal: The detergent that has been enriched with particulate matter and oil gas in step S3 is discharged as waste liquid through an overflow method and is disposed of together with kitchen waste for resource recovery. S5. Flue gas emission: The clean flue gas, after being washed and purified, is directly discharged into the air after being separated from the detergent.

2. An apparatus for implementing the method of claim 1, characterized in that, The integrated scrubber includes a detergent compartment, a flue gas network, an oil mist separator, an exhaust fan, an overflow pipe, and an oil fume collection tank. The flue gas network consists of a main intake pipe, branch intake pipes, and a distribution pipe. The end of the distribution pipe is open and submerged in the detergent in the detergent compartment. The oil mist separator is located at the top of the detergent compartment, and its inlet is connected to the purified air outlet at the top of the detergent compartment. The exhaust fan is connected to the outlet of the oil mist separator. The overflow pipe is located at the top liquid surface of the detergent in the detergent compartment, and its outlet extends into the oil fume collection tank. The branch intake pipes are symmetrically distributed along the center line of the detergent compartment cross-section, with the middle branch intake pipe being the highest and the positions gradually decreasing towards the sides. The outlet air velocity of the distribution pipe is 0.2 m / s to 3 m / s, and the immersion depth of the outlet in the detergent is 100 mm to 500 mm.

3. The device according to claim 2, characterized in that, The integrated washer is equipped with a support at the bottom, and the detergent inlet pipe is connected to the middle of the detergent compartment and the detergent underflow pipe is connected to the bottom.

4. The device according to claim 2, characterized in that, The lower part of the oil mist separator is equipped with a detergent return pipe, which returns the captured detergent to the detergent tank and immerses it below the liquid surface.

5. The device according to claim 3, characterized in that, The depth to which the end of the detergent return pipe is immersed in the detergent is not less than 50 mm.

6. The device according to claim 2, characterized in that, The outlet of the overflow pipe is immersed in the detergent in the fume collection tank to a depth of not less than 30 mm.

7. The device according to claim 2, characterized in that, The oil mist separator is a hydrocyclone demister or an inertial demister.

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