A device and method for removing grease from extraction-coupling waste alkali solution

Abstract

This invention relates to a device and method for removing grease from waste alkali solution through extraction-coalescing coupling. The device comprises a Y-flange filter, a micro-mixing extractor, an axial coalescing filter, a horizontal coalescing separator, and a settling tank. In the micro-mixing extraction module, the waste alkali solution and extractant are micro-dispersed and intensified in the mixture to improve grease extraction efficiency. After coalescence and demulsification by oleophilic / hydrophilic particles and fibers within the axial coalescing module and the horizontal coalescing separator, oil and water phases are separated in the settling zone. Suspended solids in the mixture are intercepted in the filtration module; the oil phase floats to the top and is periodically discharged. By introducing an extraction-coalescing coupling process, combined with the enhanced mixing of micro-extraction and the demulsification function of hydrophilic / hydrophobic particles, efficient removal of various oils from waste alkali solution is achieved. This invention has a compact structure and is widely applicable to the treatment of wastewater with high oil content and suspended solids, as well as the extraction treatment of high-concentration organic wastewater, especially complex wastewater containing high-viscosity oils.

Description

Technical Field

[0001] This invention relates to a waste alkaline solution extraction and coalescence coupling device and method for removing grease. It belongs to the field of petrochemicals. Background Technology

[0002] In some processes in the petrochemical and coal chemical industries, such as catalytic cracking and hydrocracking, sulfides in feedstock oil react with hydrogen under high temperature and pressure to form acidic gases such as hydrogen sulfide. These acidic gases are then removed by alkaline washing. However, this process generates waste alkaline solutions rich in complex oil contaminants, most notably high-concentration (2% to 30%) butter, a polymer formed by the reaction of unsaturated hydrocarbons with aldehydes and ketones. This butter exhibits high emulsification and exists in forms such as floating, suspended, and adhering to solid surfaces. Its high viscosity and low-temperature coking characteristics increase the difficulty of treatment. Furthermore, the waste alkaline solution also contains dissolved oil, iron filings, and suspended solids, further exacerbating the treatment challenges. Current waste alkaline solution treatment systems often encounter clogging problems due to design limitations (such as small tower diameter and packing), leading to low operating efficiency and frequent shutdowns for maintenance. Given the unstable butter content and numerous impurities in the waste alkaline solution, traditional extraction, membrane technology, adsorption, and coalescence filtration methods often face bottlenecks such as easy clogging, difficult maintenance, and incomplete oil-water separation.

[0003] To address the aforementioned problems, this invention innovatively introduces an extraction-coalescence coupling process, achieving highly efficient removal of various forms of oil from waste alkaline solutions. This ensures the continuous and stable operation of the equipment, and is simple to operate while being energy-efficient and environmentally friendly. This innovative solution is of great significance for improving the treatment efficiency of waste alkaline solutions and promoting resource recycling. Summary of the Invention

[0004] In view of the problems and defects of existing technologies and equipment, this invention provides an extraction-coalescence coupled waste alkali degreasing process and device based on microextraction to enhance mixing, the demulsification function of hydrophilic and hydrophobic particles, and the enhanced demulsification and coalescence performance of hydrophilic and hydrophobic fibers.

[0005] The technical solution adopted in this invention is as follows:

[0006] A waste alkali solution extraction-coalescence coupling degreasing device is characterized in that the device sequentially includes two Y-type flange filters, a buffer tank, a micro-mixing extractor, a shaft-type coalescing filter, a horizontal coalescing separation device, a settling tank, and an overflow tank. The two Y-type flange filters are respectively connected to the extractant inlet at the bottom of the micro-mixing extractor and the waste alkali solution inlet on the lower side wall through two buffer tanks. The micro-mixing extractor is equipped with an ejector at the bottom, a variable diameter pipe with spiral shear blades at the top, and an extractor mixture outlet at the top that connects to the first mixture inlet of the shaft-type coalescing filter.

[0007] The axial coalescing filter device includes two coalescing filter tanks connected in series. The series connection is such that the first mixed liquid outlet at the bottom of the first tank is connected by a pipe to the second mixed liquid inlet at the side of the second tank. The first mixed liquid inlet is located on the upper side of the first tank, and the second mixed liquid outlet is located at the bottom of the second tank. Each coalescing filter tank has a cavity filled with particulate packing material. Each coalescing filter tank is composed of particles of different sizes stacked together, from top to bottom: fine particles and coarse particles. Each coalescing filter tank has an oil bag at the top connected to the first drain outlet, a water bag at the bottom connected to the first or second mixed liquid outlet, and a backwash water inlet and a backwash air inlet on the bottom side.

[0008] The horizontal coalescing separator includes a horizontal tank and a cavity filled with fiber packing material inside. It is connected to the second mixed liquid outlet of the axial coalescing filter through the third mixed liquid inlet at the front end of the horizontal tank. The bottom of the tank is provided with a third mixed liquid outlet.

[0009] The settling tank is filled with corrugated plates in the middle, and has a vent and a second drain outlet at the top. The tank wall has two circular observation mirrors at the top and bottom. It is connected to the third mixed liquid outlet of the horizontal coalescing separator through the fourth mixed liquid inlet at the top, and to the overflow tank through the water phase outlet at the bottom.

[0010] The axial coalescing filter device is filled with a layer of heterogeneous hydrophilic and hydrophobic dispersed particles. The diameter to height ratio of the cavity filled with the granular filler is 1:10 to 1:8. The diameter to height ratio of the oil packing and the water packing is 1:3 to 1:2. The diameter ratio of the cavity to the tank is 1:2 to 2:3.

[0011] The fine particle packing has a particle size of 0.2–0.5 mm, and the coarse particle packing has a particle size of 0.5–1.2 mm.

[0012] The fiber filler in the horizontal coalescing separation device is a heterogeneous composite fiber layer, woven from hydrophilic and oleophilic fibers, and the fibers and the tank body are interference fit.

[0013] The present invention also provides a method for removing grease from waste alkali solution using the above-mentioned waste alkali solution grease removal device through extraction-coalescence coupling, characterized in that the method includes the following steps:

[0014] S1, waste alkali solution and extractant enter the buffer tank through Y-type flange filter respectively. The extractant is dispersed and mixed in the waste alkali solution to form micro-droplets through the injector of the micro-mixing extractor. The initially dispersed mixture enters the variable diameter pipe with spiral shear blades for swirling shearing, and multiple stages of mixing, crushing and extraction are carried out alternately.

[0015] S2. The mixture obtained in step S1 enters the shaft coalescing filter device. In the first coalescing filter tank, the butter and suspended matter in the waste alkaline solution are filtered and intercepted. Some of the mixture droplets demulsify and coalesce to complete the initial two-phase separation, while some of the mixture droplets do not complete the demulsification.

[0016] S3. The mixed liquid droplets obtained in step S2 enter the second coalescence filter tank, where large droplets in the mixed liquid that have not completed stratification and demulsification are coalesced and separated.

[0017] S4. The mixture obtained in step S3 is deeply separated by a horizontal coalescence separation unit. The tiny droplets coalesce and grow in the microchannels of the filled fiber packing bed, thus completing the two-phase separation from the extractant droplets.

[0018] S5. The extractant and treated water separated in step S4 settle in the settling tank. The extractant layer floats up and is discharged from the top outlet, while the treated water layer sinks and flows into the overflow tank from the lower water phase outlet.

[0019] S6. The fresh treated water and the settled treated water that flow into the overflow tank in step S5 are discharged from their respective outlets.

[0020] The present invention has the following beneficial effects:

[0021] 1. This invention provides a continuously operating extraction-coalescence coupled waste alkali solution oil removal process and apparatus. The apparatus includes a filtration module, a micro-mixing extraction module, a two-stage axial coalescence module, a horizontal coalescence separation module, a tank, and a settling tank. The micro-mixing extraction module disperses extractant droplets into the waste alkali solution through internal nozzles, and then enhances the mixing effect by module collision with the waste alkali solution. Subsequently, a primary particle coalescence filter bed is used to achieve initial oil droplet coalescence and growth, and a secondary particle coalescence filter bed is used to achieve deep coalescence and separation of the grown droplets that have not yet stratified. Finally, the fiber coalescence module completes deep demulsification and coalescence separation of oil in water and water in oil. After a brief clarification zone settling, the aqueous phase is discharged from the bottom, and the oil phase is discharged from the top.

[0022] 2. During operation, in response to the rapid accumulation of high-concentration suspended solids and viscous grease in the granulation module sieve section of the waste alkaline solution, the system is equipped with a backwash route to ensure treatment effectiveness. Valves can be opened and closed to regulate the release of steam bubbles, which loosen the hydrophilic and hydrophobic particles in the fluidized expansion pack and increase the particle porosity. Under the impact of incoming liquid and the bursting impact of steam bubbles, the granulation module is cleaned, and impurities float to the top of the equipment for discharge.

[0023] 3. Compared to traditional treatment methods, this invention employs a novel extraction-coalescence coupling process, achieving high-precision and effective oil removal while simultaneously enabling equipment backwashing. This invention features a compact structure, small footprint, rapid extraction and mass transfer, high efficiency, simple operation, and energy savings. It is suitable for treating all types of wastewater with high oil content and suspended solids, as well as extracting high-concentration organic wastewater, especially complex wastewater containing highly viscous oils. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the waste alkaline solution extraction coalescence coupling degreasing device of the present invention;

[0025] Figure 2 This is a schematic diagram of the buffer tank structure;

[0026] Figure 3 This is a schematic diagram of the micromixing extraction device.

[0027] Figure 4 This is a schematic diagram of a shaft-type coalescing filter device.

[0028] Figure 5 Schematic diagram of a horizontal coalescing and separation device

[0029] Figure 6 This is a schematic diagram of the settling tank device.

[0030] The components include: 1. Filter; 2. Buffer tank; 3. Pump; 4. Micro-mixing extractor; 5. Shaft-type coalescing filter; 6. Horizontal coalescing separator; 7. Settling tank; 8. Overflow tank; 9. Flow meter; 1-1. First mixed liquid inlet; 1-2. First mixed liquid outlet; 1-3. Second mixed liquid inlet; 1-4. Second mixed liquid outlet; 2-1. Vent; 2-2. Drain outlet; 2-3. Pressure gauge; 2-4. Observation mirror; 2-5. Outer cylinder; 2-6. Outer cylinder; 2-7. Inlet; 4-1. Mixed liquid outlet; 4-2. Spiral blade; 4-3. Reducing pipe; 4-4. Ejector; 4-5. Extractant inlet; 4 -6. Waste alkali inlet; 4-7. Outer cylinder; 5-1. First drain outlet; 5-2. Oil tank; 5-3. Observation mirror; 5-4. Water vent; 5-5. Packing particles; 5-6. Water tank; 5-7. Mixed liquid outlet; 5-8. Backwash water inlet; 5-9. Backwash steam inlet; 5-10. Outer cylinder; 5-11. Mixed liquid inlet; 6-1. Third mixed liquid inlet; 6-2. Outer cylinder; 6-3. Fiber packing; 6-4. Third mixed liquid outlet; 7-1. Vent outlet; 7-2. Second drain outlet; 7-3. Observation mirror; 7-4. Corrugated plate; 7-5. Treated water outlet; 7-6. Outer cylinder; 7-7. Fourth mixed liquid inlet. Detailed Implementation

[0031] The present invention will be further described in detail below with reference to embodiments. It should be understood that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention still fall within the scope of protection of the present invention.

[0032] Example 1

[0033] Figure 1 The present invention relates to a method and apparatus for removing grease from waste alkali solution using an extraction-coalescing coupling method. The extraction-coalescing coupling waste alkali solution grease removal apparatus includes a filter 1, a buffer tank 2, a micro-mixing extractor 4, an axial coalescing filter 5, and a horizontal coalescing separator 6. In the filter 1, most suspended solids and solid impurities in the waste alkali solution and extractant are filtered and separated. The waste alkali solution and extractant are thoroughly mixed and extracted in the micro-mixing extractor 4. When the mixture enters the axial coalescing filter 5 through the first mixture inlet 1-1, residual suspended solids and solid impurities are intercepted in the primary coalescing particle module, and preliminary coalescing and separation of the oil and water two-phase droplets are completed. Further deep coalescing and separation are performed in the secondary coalescing particle module, where suspended oil and dispersed oil are separated. The mixture then enters the horizontal coalescing separator 6 for deep demulsification and coalescing separation of the small-particle-size emulsion oil. Finally, the mixture enters the settling tank 7 for stratification, with the oil phase floating and the water phase settling. During operation, the accumulation of suspended solids and solid impurities in the particle agglomeration area will affect the oil removal effect. Therefore, a backwash water inlet 5-8 and a backwash steam inlet 5-9 are provided. The clean water and steam cause the particles to float, tumble and expand the porosity in the device, thereby cleaning the particles. The suspended solids and solid impurities are discharged through the first drain outlet 5-1.

[0034] The method for removing oil from waste alkaline solution using the above-mentioned device comprises the following steps:

[0035] (1) Waste alkaline solution and extractant are filtered through filter 1 to remove most of the suspended solids and solid impurities. The pressure is buffered and the flow rate is adjusted in the buffer tank. The enhanced extraction process is completed through micro-mixing extractor 4. Then, it enters shaft coalescing filter 5 to capture and separate the suspended oil and dispersed oil.

[0036] (2) The mixture after the separation of suspended oil and dispersed oil enters the horizontal coalescence separator 6 to demulsify and separate the emulsified oil with small particle size, and then enters the settling tank 7 to complete the oil-water separation.

[0037] (3) During operation, the accumulation of suspended solids and solid impurities in the particle agglomeration part will affect the oil removal effect. Therefore, a backwash water inlet 5-8 and a backwash steam inlet 5-9 are provided. The particles are made to float, roll and expand the porosity in the device by using clean water and steam to achieve particle cleaning. Suspended solids and solid impurities are discharged through the first drain outlet 5-1. Water is continuously fed and discharged during the cleaning process until the effluent sample is clear and free of impurities.

[0038] Example 2

[0039] A pilot-scale test of the degreasing effect of the method and apparatus of this invention was conducted at an ethylene plant. The degreasing waste alkaline solution was then subjected to subsequent biochemical treatment. The extractant was pyrolysis gasoline, a byproduct of ethylene production, to save costs.

[0040] The device is constructed as a skid frame, 1950mm long, 60mm wide, and 1580mm high. The particle bed, approximately 700mm high, is composed of stacked oleophilic and hydrophilic particles of varying sizes. The fiber bed, approximately 400mm long and woven from hydrophilic and oleophilic fibers, is an interference fit with the tank body. The buffer and settling tanks have a combined capacity of approximately 3L.

[0041] The throughput of this experiment was 4 L / h, and the amount of pyrolysis gasoline used was also 4 L / h, meaning the ratio of waste alkali solution to extractant was 1:1. The oil content in the waste alkali solution fluctuated between 10,000 and 150,000 mg / L. After a period of stable operation, samples were taken at the outlet, and the oil removal and suspension removal effects of the device were evaluated using an infrared oil analyzer and a turbidity analyzer. The results are shown in Table 1.

[0042] Table 1

[0043]

Claims

1. A waste alkaline solution extraction and coalescence coupling device for removing grease, characterized in that, The device sequentially includes two Y-flange filters, a buffer tank, a micro-mixing extractor, a shaft-type coalescing filter, a horizontal coalescing separator, a settling tank, and an overflow tank. The two Y-flange filters are connected to the extractant inlet at the bottom of the micro-mixing extractor and the waste alkali inlet on the lower side wall through two buffer tanks, respectively. The micro-mixing extractor is equipped with an ejector at the bottom, a variable-diameter pipe with spiral shear blades at the top, and an extractor mixture outlet at the top that connects to the first mixture inlet of the shaft-type coalescing filter. The axial coalescing filter device includes two coalescing filter tanks connected in series. The series connection is such that the first mixed liquid outlet at the bottom of the first tank is connected by a pipe to the second mixed liquid inlet at the side of the second tank. The first mixed liquid inlet is located on the upper side of the first tank, and the second mixed liquid outlet is located at the bottom of the second tank. Each coalescing filter tank has a cavity filled with particulate packing material. Each coalescing filter tank is composed of particles of different sizes stacked together, from top to bottom: fine particles and coarse particles. Each coalescing filter tank has an oil bag at the top connected to the first drain outlet, a water bag at the bottom connected to the first or second mixed liquid outlet, and a backwash water inlet and a backwash air inlet on the bottom side. The horizontal coalescing separator includes a horizontal tank and a cavity filled with fiber packing material inside. It is connected to the second mixed liquid outlet of the axial coalescing filter through the third mixed liquid inlet at the front end of the horizontal tank. The bottom of the tank is provided with a third mixed liquid outlet. The settling tank is filled with corrugated plates in the middle, and has a vent and a second drain outlet at the top. The tank wall has two circular observation mirrors at the top and bottom. It is connected to the third mixed liquid outlet of the horizontal coalescing separator through the fourth mixed liquid inlet at the top, and to the overflow tank through the water phase outlet at the bottom.

2. The waste alkali solution extraction-coalescence coupling degreasing device as described in claim 1, characterized in that, The axial coalescing filter device is filled with a layer of heterogeneous hydrophilic and hydrophobic dispersed particles. The diameter to height ratio of the cavity filled with the granular filler is 1:10 to 1:

8. The diameter to height ratio of the oil packing and the water packing is 1:3 to 1:

2. The diameter ratio of the cavity to the tank is 1:2 to 2:

3.

3. The waste alkali solution extraction-coalescence coupling degreasing device as described in claim 1, characterized in that, The fine particles in the granular filler have a particle size of 0.2–0.5 mm, and the coarse particles have a particle size of 0.5–1.2 mm.

4. The waste alkali solution extraction-coalescence coupling degreasing device as described in claim 1, characterized in that, The fiber filler in the horizontal coalescing separation device is a heterogeneous composite fiber layer, woven from hydrophilic and oleophilic fibers, and the fibers and the tank body are interference fit.

5. A method for removing grease from waste alkaline solution using the apparatus described in any one of claims 1-4, characterized in that, The method includes the following steps: S1, waste alkali solution and extractant enter the buffer tank through Y-type flange filter respectively. The extractant is dispersed and mixed in the waste alkali solution to form micro-droplets through the injector of the micro-mixing extractor. The initially dispersed mixture enters the variable diameter pipe with spiral shear blades for swirling shearing, and multiple stages of mixing, crushing and extraction are carried out alternately. S2. The mixture obtained in step S1 enters the shaft coalescing filter device. In the first coalescing filter tank, the butter and suspended matter in the waste alkaline solution are filtered and intercepted. Some of the mixture droplets demulsify and coalesce to complete the initial two-phase separation, while some of the mixture droplets do not complete the demulsification. S3. The mixed liquid droplets obtained in step S2 enter the second coalescence filter tank, where large droplets in the mixed liquid that have not completed stratification and demulsification are coalesced and separated. S4. The mixture obtained in step S3 is deeply separated by a horizontal coalescence separation unit. The tiny droplets coalesce and grow in the microchannels of the filled fiber packing bed, thus completing the two-phase separation from the extractant droplets. S5. The extractant and treated water separated in step S4 settle in the settling tank. The extractant layer floats up and is discharged from the top outlet, while the treated water layer sinks and flows into the overflow tank from the lower water phase outlet. S6. The fresh treated water and the settled treated water that flow into the overflow tank in step S5 are discharged from their respective outlets.

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