Method for carrying out three-phase separation on kitchen garbage by adopting supercritical fluid

Abstract

The invention relates to a method for carrying out three-phase separation on kitchen garbage by adopting supercritical fluid, which comprises the following steps of: 1, introducing gaseous carbon dioxide into a supercritical fluid generating device, and working the supercritical fluid generating device to generate supercritical carbon dioxide fluid; 2, after kitchen garbage is subjected to sorting pretreatment, the kitchen garbage is conveyed into a kitchen garbage treatment assembly, and a solid-oil-liquid mixture is formed; 3, conveying the solid-oil liquid mixture generated in the step 2 to a reaction kettle, and introducing the supercritical carbon dioxide fluid generated in the step 1 so as to separate out an oil-phase substance, a liquid-phase substance and a solid-phase substance; the method has the characteristics of high resource recycling rate and remarkable separation efficiency, the separated grease can be converted into biodiesel and other energy products, the solid phase is used for high-quality composting, the liquid phase is reasonably treated, full-chain resource utilization of the kitchen garbage is realized, and considerable economic benefits are brought.

Description

Technical Field

[0001] The present invention relates to the technical field of kitchen waste treatment, and in particular to a method for performing three-phase separation of kitchen waste by using a supercritical fluid. Background Art

[0002] The dry matter of kitchen waste is rich in organic substances such as carbohydrates, proteins and oils, and has important potential for resource and energy utilization; the composition and existence form of oils in kitchen waste are complex, and the main existence forms include emulsified oil, dispersed oil, dissolved oil and suspended oil; however, the current traditional separation technology has many problems such as incomplete separation, high energy consumption, and easy to cause secondary pollution. Supercritical fluids have unique physical and chemical properties, such as density between gas and liquid, high diffusivity and solubility, which have opened up new ways for efficient and clean treatment of kitchen waste. Therefore, we designed a method for three-phase separation of kitchen waste using supercritical fluids.

[0003] Patent No. CN202111422487.9 is a Chinese invention patent, which discloses a method for three-phase separation of kitchen waste using supercritical fluid, and relates to the technical field of kitchen waste treatment; specifically: mixing kitchen waste with supercritical fluid, dehydrating and deoiling the kitchen waste, and separating the solid phase, water phase, and oil phase; the method for three-phase separation of kitchen waste using supercritical fluid proposed in the invention can achieve efficient oil extraction and water removal of kitchen waste on the basis of avoiding traditional mechanical extrusion methods, thereby obtaining an oil removal rate of 70-82% and a dehydration rate of 80-85%, but the invention has the following problems: first, it does not have the thermal hydrolysis treatment of kitchen waste. After the kitchen waste is generally crushed, most of the cell tissues are still in an intact state, and the oil yield is not high. Secondly, it does not have the recycling of supercritical fluid, and the treatment cost is high. Summary of the invention

[0004] The purpose of the present invention is to solve the technical problems of incomplete separation, high energy consumption and easy secondary pollution in the current traditional separation technology by providing supercritical carbon dioxide fluid, thermal hydrolysis device and steam generator.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A method for three-phase separation of kitchen waste using supercritical fluid comprises the following steps:

[0007] Step 1: introducing gaseous carbon dioxide into a supercritical fluid generating device, and the supercritical fluid generating device operates to generate supercritical carbon dioxide fluid;

[0008] Step 2: After sorting and pre-processing the kitchen waste, the kitchen waste is transported into the kitchen waste processing component to form a solid-oil-liquid mixture;

[0009] Step 3: transporting the solid-oil-liquid mixture produced in step 2 to a reactor, and introducing the supercritical carbon dioxide fluid produced in step 1, thereby separating out oil phase substances, liquid phase substances, and solid phase substances;

[0010] Step 4: Separate and purify the oil phase substance, liquid phase substance and solid phase substance produced in step 3 to form supercritical carbon dioxide fluid, biological fixed fertilizer, oil and fat, and water phase, and the extracted carbon dioxide is circulated to the supercritical fluid generating device for recycling.

[0011] As a preferred embodiment, the food waste treatment component comprises a crusher, the outlet of the crusher is connected to a thermal hydrolysis device, and the outlet of the thermal hydrolysis device is connected to a reactor.

[0012] As a preferred embodiment, the step three comprises the following steps:

[0013] Step a: injecting supercritical carbon dioxide fluid into the reactor, allowing the supercritical carbon dioxide fluid to fully interact with the solid-oil-liquid mixture in step 2 at a flow rate of 0.5-1.1.5 liters per minute, so that the oil component is quickly dissolved in the supercritical carbon dioxide fluid to form an oil phase substance, and discharged into the first separation device;

[0014] Step b: The pressure in the reactor is suddenly reduced to normal pressure by means of a pressure reducing device, and the remaining solid-liquid mixture is fully mixed with the supercritical carbon dioxide fluid to cause the solid phase impurities to precipitate and form a solid phase substance, which is collected by a filtering device, and the remaining liquid phase components are mixed with the supercritical carbon dioxide fluid to form a liquid phase substance, which is discharged into a gas-liquid separation device.

[0015] As a preferred embodiment, in step a, the temperature in the reactor is controlled at 35-45 degrees Celsius, the pressure is maintained at 8-10 MPa, and the continuous action time is set to 25-75 minutes.

[0016] As a preferred embodiment, in the step b, the pressure reducing device adjusts the pressure to 4-6 MPa and the temperature is maintained at 35-40 degrees Celsius. When the remaining solid-liquid mixture in the step b is fully mixed with the supercritical carbon dioxide fluid, the reactor adjusts the parameters to reduce the pressure to 2-3 MPa and the temperature is maintained at 30-35 degrees Celsius.

[0017] As a preferred embodiment, the pressure of the No. 1 separation device is set to 4-6 MPa, the temperature is maintained at 35-40 degrees Celsius, the separated oil is transported to the microalgae cultivation and concentration system, and the separated supercritical carbon dioxide fluid enters the gas-liquid separation device.

[0018] As a preferred embodiment, the filtering device is connected to an aerobic composting treatment device, the compost humidity of the aerobic composting treatment device is controlled at 40%-60%, the temperature is stabilized at 50-70 degrees Celsius, and a microbial composite agent is added to the aerobic composting treatment device and mixed with the solid phase material for 15-30 days.

[0019] As a preference, the gas outlet of the gas-liquid separation device is connected to a supercritical fluid generating device, and the liquid outlet of the gas-liquid separation device is connected to a water quality detection and treatment device, an outlet of the water quality detection and treatment device is connected to a steam generating device, and the steam generating device is connected to a thermal hydrolysis device.

[0020] Beneficial effects of the present invention:

[0021] (1) The present invention uses supercritical carbon dioxide fluid to promote the three-phase separation of kitchen waste. On the one hand, no harmful gas is emitted during the entire process, which improves environmental protection and increases the purity of each phase of the separated materials. On the other hand, the continuous recycling of carbon dioxide is achieved, which reduces processing costs and increases green sustainability.

[0022] (2) In the present invention, a thermal hydrolysis device is provided to change the physical and chemical properties of the kitchen waste through the action of high temperature and high pressure, thereby greatly improving its solid-liquid and oil-water separation characteristics. After the water phase of the three-phase separation of the kitchen waste meets the discharge standard after being tested by a water quality testing and treatment device, it is recycled into a steam generating device, and then the water vapor generated is reused by the thermal hydrolysis device, thereby increasing the utilization rate of the water phase.

[0023] (3) The present invention has the characteristics of high resource recovery rate and significant separation efficiency. The separated oil can be converted into energy products such as biodiesel. The solid phase can be used for high-quality compost and the liquid phase can be properly disposed of, thereby realizing the resource utilization of the entire chain of kitchen waste and bringing considerable economic benefits.

[0024] To sum up, the invention has the advantages of high resource recycling rate and significant separation efficiency, and is particularly suitable for the field of kitchen waste treatment technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0026] Figure 1 It is a schematic diagram of the overall structure of the present invention. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present invention are clearly and completely described below in conjunction with the accompanying drawings.

[0028] Embodiment 1

[0029] like Figure 1 As shown, the present invention provides a method for three-phase separation of kitchen waste using supercritical fluid, comprising the following steps:

[0030] Step 1: Introduce gaseous carbon dioxide into a supercritical fluid generator. The supercritical fluid generator generates supercritical carbon dioxide fluid, which has similar diffusivity to gas and solubility to liquid. It also has the characteristics of low viscosity and low surface tension, so that the supercritical carbon dioxide fluid can quickly penetrate into microporous substances. Therefore, when used for extraction, the extraction rate is faster and more effective than that of liquid. In particular, the solubility can change with temperature, pressure and polarity. In addition, the supercritical carbon dioxide fluid does not emit harmful gases during the decomposition process, which improves environmental protection and increases the purity of each phase of the separated materials.

[0031] Step 2: After sorting and pre-processing the kitchen waste, the kitchen waste is transported into the kitchen waste processing component to form a solid-oil-liquid mixture;

[0032] Step 3: transporting the solid-oil-liquid mixture produced in step 2 to a reactor, and introducing the supercritical carbon dioxide fluid produced in step 1, thereby separating out oil phase substances, liquid phase substances, and solid phase substances;

[0033] Step 4: Separate and purify the oil phase, liquid phase and solid phase produced in step 3 to form supercritical carbon dioxide fluid, bio-fixed fertilizer, oil and fat, and water phase. The extracted carbon dioxide is circulated to the supercritical fluid generating device for recycling, thereby achieving continuous recycling of carbon dioxide, reducing processing costs and increasing green sustainability.

[0034] Furthermore, the kitchen waste treatment component includes a crusher, the outlet of the crusher is connected to a thermal hydrolysis device, and the outlet of the thermal hydrolysis device is connected to a reactor. After the kitchen waste is crushed in the crusher, it is transported to the thermal hydrolysis device for thermal hydrolysis treatment. Through the action of high temperature and high pressure, the physical and chemical properties of the kitchen waste are changed, and its solid-liquid and oil-water separation characteristics are greatly improved. After the water phase of the three-phase separation of the kitchen waste is tested by a water quality testing and treatment equipment and meets the emission standards, it is recycled into a steam generating device, and then the water vapor generated is reused by the thermal hydrolysis device, thereby increasing the utilization rate of the water phase.

[0035] Further, if Figure 1 As shown, the step three includes the following steps:

[0036] Step a: injecting supercritical carbon dioxide fluid into the reactor, allowing the supercritical carbon dioxide fluid to fully interact with the solid-oil-liquid mixture in step 2 at a flow rate of 0.5-1.1.5 liters per minute, so that the oil component is quickly dissolved in the supercritical carbon dioxide fluid to form an oil phase substance, and discharged into the first separation device. This step completes the separation of the oil phase substance;

[0037] Step b: The pressure in the reactor is suddenly reduced to normal pressure by means of a pressure reducing device, and the remaining solid-liquid mixture is fully mixed with the supercritical carbon dioxide fluid to cause the solid phase impurities to precipitate and form a solid phase substance, which is collected by a filtering device, and the remaining liquid phase components are mixed with the supercritical carbon dioxide fluid to form a liquid phase substance, which is discharged into a gas-liquid separation device. The filtering device retains the solid phase substance in its upper part and filters the liquid phase substance to its lower part to achieve solid-liquid separation. The solid phase substance is transported to an aerobic composting treatment device for composting treatment, and the liquid phase substance is transported to a gas-liquid separation device for gas-liquid separation to increase the purity of the gaseous carbon dioxide.

[0038] Furthermore, in step a, the temperature in the reactor is controlled at 35-45 degrees Celsius, the pressure is maintained at 8-10 MPa, and the continuous action time is set to 25-75 minutes, so as to efficiently dissolve and separate the oil components therein and realize accurate extraction of the oil phase.

[0039] Further, in the step b, the pressure reducing device adjusts the pressure to 4-6 MPa and the temperature is maintained at 35-40 degrees Celsius. At this time, the oil phase material in the reactor enters the primary separation device. Due to the pressure reduction, the solubility of the oil in the supercritical carbon dioxide fluid decreases, and the preliminary separation of the oil and the supercritical carbon dioxide fluid is achieved. When the remaining solid-liquid mixture in the step b is fully mixed with the supercritical carbon dioxide fluid, the reactor is adjusted to reduce the pressure to 2-3 MPa and the temperature is maintained at 30-35 degrees Celsius, so that solid-phase impurities are forced to precipitate from the supercritical carbon dioxide fluid, and the solid-phase material is collected by the filtering device.

[0040] Furthermore, the pressure of the No. 1 separation device is set to 4-6 MPa, and the temperature is maintained at 35-40 degrees Celsius. The separated oil is transported to the microalgae cultivation and concentration system, where the oil reacts with the microalgae photobiology to form biodiesel. The separated supercritical carbon dioxide fluid enters the gas-liquid separation device and is converted into gaseous carbon dioxide, thereby realizing the continuous recycling of carbon dioxide, reducing processing costs, and increasing green sustainability.

[0041] Furthermore, the filtering device is connected to an aerobic composting treatment device, the compost humidity of the aerobic composting treatment device is controlled at 40%-60%, the temperature is stabilized at 50-70 degrees Celsius, and a microbial composite agent is added into the aerobic composting treatment device and mixed with the solid phase material for 15-30 days. The microbial composite agent contains Bacillus subtilis, yeast, and lactic acid bacteria in a quantity ratio of 2:1:1-4:2:1. The solid material is aerobically composted and converted into high-quality organic fertilizer after 15-30 days of decomposition.

[0042] Further, if Figure 1 As shown, the gas outlet of the gas-liquid separation device is connected to the supercritical fluid generating device, and the liquid outlet of the gas-liquid separation device is connected to the water quality detection and treatment equipment; the outlet of the water quality detection and treatment equipment is connected to the steam generating device, and the steam generating device is connected to the thermal hydrolysis device. The liquid phase material realizes gas-liquid separation in the gas-liquid separation device. On the one hand, the gaseous carbon dioxide is generated and recycled to the supercritical fluid generating device to increase the utilization rate of the carbon dioxide. On the other hand, the generated water phase is transported to the water quality detection and treatment equipment to obtain water quality detection and purification treatment. A part of the water phase that meets the standards is discharged, and a part is recycled to the steam generating device to generate water vapor. The water vapor is utilized by the thermal hydrolysis device to increase the utilization rate of the water phase.

[0043] Working process: first, introduce gaseous carbon dioxide into the supercritical fluid generating device, and the supercritical fluid generating device works to generate supercritical carbon dioxide fluid; at the same time, sort and pre-treat the kitchen waste, and then transport it to the kitchen waste treatment component to form a solid-oil-liquid mixture; further, transport the solid-oil-liquid mixture to the reactor, and introduce supercritical carbon dioxide fluid, thereby separating oil phase substances, liquid phase substances, and solid phase substances; further, separate the oil phase substances from the supercritical carbon dioxide fluid in the No. 1 separation device, and transport the separated oil to the microalgae cultivation and concentration system, and the separated supercritical carbon dioxide fluid is transported to the No. 2 separation device, and the separated oil is transported to the microalgae cultivation and concentration system, and the separated supercritical carbon dioxide fluid is transported to the No. 3 separation device, and the separated oil is transported to the microalgae cultivation and concentration system, and the separated supercritical carbon dioxide fluid is transported to the No. 1 separation device, and the separated supercritical carbon dioxide fluid is transported to the No. 2 ... supercritical carbon dioxide fluid. The carbon dioxide fluid enters the gas-liquid separation device and is converted into gaseous carbon dioxide. Further, the liquid phase material is separated into gas and liquid in the gas-liquid separation device. On the one hand, the generated gaseous carbon dioxide is recycled to the supercritical fluid generation device to increase the utilization rate of carbon dioxide. On the other hand, the generated water phase is transported to the water quality detection and treatment equipment to obtain water quality detection and purification treatment. A part of the water phase that meets the standards is discharged, and a part is recycled to the steam generation device to generate water vapor, which is utilized by the thermal hydrolysis device. Further, the solid phase material is decomposed in the aerobic composting treatment equipment for 15-30 days and converted into high-quality organic fertilizer.

[0044] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by the terms "front and back", "left and right", etc. are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or component referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the invention.

[0045] Of course, in the present technical solution, those skilled in the art should understand that the term "one" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element may be one, while in another embodiment, the number of the element may be multiple, and the term "one" should not be understood as a limitation on the quantity.

[0046] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art under the technical guidance of the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for three-phase separation of kitchen waste using supercritical fluid, characterized in that: The following steps are involved: Step 1: introducing gaseous carbon dioxide into a supercritical fluid generating device, and the supercritical fluid generating device operates to generate supercritical carbon dioxide fluid; Step 2: After sorting and pre-processing the kitchen waste, the kitchen waste is transported into the kitchen waste processing component to form a solid-oil-liquid mixture; Step 3: transporting the solid-oil-liquid mixture produced in step 2 to a reactor, and introducing the supercritical carbon dioxide fluid produced in step 1, thereby separating out oil phase substances, liquid phase substances, and solid phase substances; Step 4: Separate and purify the oil phase substance, liquid phase substance and solid phase substance produced in step 3 to form supercritical carbon dioxide fluid, biological fixed fertilizer, oil and fat, and water phase, and the extracted carbon dioxide is circulated to the supercritical fluid generating device for recycling.

2. The method for three-phase separation of kitchen waste using supercritical fluid according to claim 1, characterized in that: The kitchen waste treatment component comprises a crusher, an outlet of the crusher is connected to a thermal hydrolysis device, and an outlet of the thermal hydrolysis device is connected to a reactor.

3. The method for three-phase separation of kitchen waste using supercritical fluid according to claim 1, characterized in that: The step three comprises the following steps: Step a: injecting supercritical carbon dioxide fluid into the reactor, allowing the supercritical carbon dioxide fluid to fully interact with the solid-oil-liquid mixture in step 2 at a flow rate of 0.5-1.1.5 liters per minute, so that the oil component is quickly dissolved in the supercritical carbon dioxide fluid to form an oil phase substance, and discharged into the first separation device; Step b: The pressure in the reactor is suddenly reduced to normal pressure by means of a pressure reducing device, and the remaining solid-liquid mixture is fully mixed with the supercritical carbon dioxide fluid to cause the solid phase impurities to precipitate and form a solid phase substance, which is collected by a filtering device, and the remaining liquid phase components are mixed with the supercritical carbon dioxide fluid to form a liquid phase substance, which is discharged into a gas-liquid separation device.

4. The method for three-phase separation of kitchen waste using a supercritical fluid according to claim 3, characterized in that: In the step a, the temperature in the reactor is controlled at 35-45 degrees Celsius, the pressure is maintained at 8-10 MPa, and the continuous action time is set to 25-75 minutes.

5. The method for three-phase separation of kitchen waste using supercritical fluid according to claim 3, characterized in that: In step b, the pressure reducing device adjusts the pressure to 4-6 MPa and maintains the temperature at 35-40 degrees Celsius. When the remaining solid-liquid mixture in step b is fully mixed with the supercritical carbon dioxide fluid, the reactor adjusts the parameters to reduce the pressure to 2-3 MPa and maintain the temperature at 30-35 degrees Celsius.

6. The method for three-phase separation of kitchen waste using supercritical fluid according to claim 3, characterized in that: The pressure of the No. 1 separation device is set to 4-6 MPa, and the temperature is maintained at 35-40 degrees Celsius. The separated oil is transported to the microalgae cultivation and concentration system, and the separated supercritical carbon dioxide fluid enters the gas-liquid separation device.

7. The method for three-phase separation of kitchen waste using supercritical fluid according to claim 3, characterized in that: The filtering device is connected to an aerobic composting treatment device, the compost humidity of the aerobic composting treatment device is controlled at 40%-60%, the temperature is stabilized at 50-70 degrees Celsius, and a microbial composite agent is added into the aerobic composting treatment device and mixed with solid phase substances for 15-30 days.

8. The method for three-phase separation of kitchen waste using supercritical fluid according to claim 3, characterized in that: The gas outlet of the gas-liquid separation device is connected to a supercritical fluid generating device, and the liquid outlet of the gas-liquid separation device is connected to a water quality detection and treatment device, an outlet of the water quality detection and treatment device is connected to a steam generating device, and the steam generating device is connected to a thermal hydrolysis device.

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