Regeneration process of waste lubricating oil of wind power gear box

Abstract

The invention discloses a regeneration process of waste lubricating oil of a wind power gear box, which comprises the following steps: S1, introducing the waste lubricating oil into a wire mesh filtering device to obtain preliminary filtered oil; s2, pumping the preliminarily filtered oil into a closed pretreatment tank, and introducing nitrogen for steam stripping dehydration to obtain dehydrated waste oil; s3, stirring the dehydrated waste oil, and adding a pretreatment agent A at the same time; pumping the reaction mixture into a standing settling tank, separating out residues after solid and liquid are completely layered, and collecting supernatant liquid at the same time; s4, pumping the supernatant into a first-stage adsorption refining reaction kettle, and adding an adsorbent B; after the reaction is finished, conveying to a first plate-and-frame filter to obtain primary adsorption refined oil; s5, pumping the primary adsorption refining oil into a secondary adsorption refining reaction kettle, and adding an adsorbent C; and after the reaction is finished, conveying to a second plate-and-frame filter to obtain regenerated base oil. The method has the characteristics of thorough impurity removal, high purity of regenerated base oil and high regeneration yield.

Description

Technical Field

[0001] This invention relates to a regeneration process for waste lubricating oil in wind turbine gearboxes. Background Technology

[0002] The operating environment of wind turbines is extremely challenging: inland turbines must withstand harsh conditions such as large temperature differences between day and night and frequent sandstorms, while coastal and offshore turbines face continuous erosion from water vapor and seawater, resulting in complex and variable operating conditions. More importantly, the nacelles housing wind turbine gearboxes are mostly located more than 80 meters above the ground, making component maintenance and replacement extremely costly. This necessitates minimizing component damage caused by lubrication failures. Furthermore, the operating conditions of the various friction pairs within the wind turbine gearbox vary significantly, encompassing low-speed heavy loads and high-speed light loads, thus placing extremely high demands on gear oil performance—requiring the use of specialized wind turbine gear oil to ensure high-reliability operation of the equipment.

[0003] With the growth of wind power installed capacity, the domestic demand for high-end wind turbine gear oil has been increasing year by year, resulting in a continuous increase in the amount of waste wind turbine gear oil. Directly discarding or incinerating this waste oil would not only cause serious environmental pollution but also represent a huge waste of energy resources. It is worth noting that wind turbine gear oil, as a high-end fully synthetic lubricant, uses polyalphaolefin (PAO) as its base oil. Currently, high-viscosity mPAO is entirely produced abroad and boasts excellent performance. Furthermore, in waste wind turbine gear oil, the retention rate of PAO base oil is as high as 90%-98%, with most molecular structures remaining unchanged or showing only slight alterations, possessing extremely high regeneration value. Therefore, developing a scientific and reasonable regeneration process for waste wind turbine gear oil has become a key breakthrough in solving the problems of resource waste and environmental pollution.

[0004] The core objective of waste oil regeneration is to remove non-ideal components (including deteriorating additives, acidic oxides, moisture, dust, and abrasive metal particles) from waste oil through physical or chemical means, ultimately obtaining regenerated base oil whose physicochemical properties meet base oil standards. From a technological development perspective, waste oil regeneration processes for lubricating oil have evolved from the early acid-clay method to acid-free and hydrogenation methods. Currently, mainstream regeneration processes both domestically and internationally include distillation-clay refining, distillation-solvent refining-clay supplementary refining, and distillation-hydrogenation processes. However, these processes generally have significant drawbacks: large equipment investment, low regenerated product yield, and poor product quality (for example, regenerated oil produced by the distillation-hydrogenation process has poor light stability and is prone to viscosity reduction due to cracking). Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technology and provide a regeneration process for waste lubricating oil in wind turbine gearboxes. This process features thorough impurity removal, high purity of the regenerated base oil, high regeneration yield, and low equipment investment.

[0006] The technical solution to achieve the above objective is: a regeneration process for waste lubricating oil in wind turbine gearboxes, comprising the following steps: S1. Pass the waste lubricating oil into a metal wire mesh filter to trap and remove large mechanical impurities with a particle size ≥40 mesh from the waste lubricating oil, and obtain preliminary filtered oil. S2. Pump the preliminary filtered oil obtained in step S1 into a closed pretreatment tank, start the heating device in the pretreatment tank to raise the oil temperature, and at the same time, introduce nitrogen gas with a purity of ≥99.5% from the bottom of the pretreatment tank for stripping and dehydration until the water content in the preliminary filtered oil is ≤0.03%. Stop heating and introducing nitrogen gas to obtain dehydrated waste oil. S3. Keep the pretreatment tank sealed, start the agitator in the pretreatment tank to stir the dehydrated waste oil obtained in step S2, and slowly add pretreatment agent A from the top feed port of the pretreatment tank. The amount of pretreatment agent A added is 0.8-3% of the mass of the dehydrated waste oil. The agitator continues to stir so that the pretreatment agent A reacts with the dehydrated waste oil. After the reaction is completed, the agitator stops stirring and the reaction mixture is pumped into the settling tank. The mixture settles naturally in the settling tank. After the solid and liquid phases of the reaction mixture are completely separated, the residue is separated from the bottom slag discharge port of the settling tank, and the clear liquid in the settling tank is collected at the same time. S4. Pump the supernatant obtained in step S3 into a primary adsorption refining reactor with a heating jacket. Start the stirring device in the primary adsorption refining reactor and heat it. After the temperature in the primary adsorption refining reactor rises, add adsorbent B to the primary adsorption refining reactor. The amount of adsorbent B added is 3-8% of the mass of the supernatant. Maintain the temperature and stirring rate to allow adsorbent B to carry out the adsorption refining reaction with the supernatant. After the reaction is completed, the reaction mixture is transported to the first plate and frame filter press through the first pressurization pump. Filter the mixture in the first plate and frame filter press to retain the adsorbent residue and obtain the primary adsorbed refined oil. S5. Pump the primary adsorption refined oil obtained in step S4 into a secondary adsorption refined reactor with a heating jacket. Start the stirring device in the secondary adsorption refined reactor and heat it. After the temperature in the secondary adsorption refined reactor rises, add adsorbent C to the secondary adsorption refined reactor. The amount of adsorbent C added is 1-6% of the mass of the primary adsorption refined oil. Maintain the temperature and stirring rate to allow the adsorbent C to undergo an adsorption and refining reaction with the primary adsorption refined oil. After the reaction is completed, the reaction mixture is transported to the inlet of the second plate and frame filter press through the second pressurized pump. Filter the mixture in the second plate and frame filter press to retain the adsorbent residue and obtain the regenerated base oil.

[0007] In the aforementioned wind turbine gearbox waste lubricating oil regeneration process, during step S1, the metal mesh in the metal mesh filter device is 40-80 mesh; the material of the metal mesh is 304 stainless steel or 316L stainless steel; the metal mesh filter device is equipped with a backwashing interface, and the filter is applied every 50-100m... 3 After the waste oil is removed, it is backwashed.

[0008] In the aforementioned wind turbine gearbox waste lubricating oil regeneration process, during step S2, the heating and dehydration temperature is 100-150℃, and the nitrogen stripping rate is 0.5-2m / s. 3 / h, the criterion for determining the dehydration endpoint is: the displayed value of the moisture detector at the gas phase outlet at the top of the pretreatment tank is ≤0.03%.

[0009] In the above-mentioned wind turbine gearbox waste lubricating oil regeneration process, during step S3, the pretreatment agent A is a mixture containing alkylammonium hydroxylate and imidazole carboxylate; the molecular weight of the alkylammonium hydroxylate is 300-500, the molecular weight of the imidazole carboxylate is 180-220, and the mixing ratio of the alkylammonium hydroxylate and the imidazole carboxylate is 2-8:8-2; the addition rate of pretreatment agent A is 0.1-0.5 kg / min; the amount of pretreatment agent A added is 0.8-2% of the mass of the dehydrated waste oil; the stirring speed of the agitator in the pretreatment tank is 100-300 r / min; the reaction time is 5-30 minutes; the temperature of natural settling in the static settling tank is 30-50℃; and the settling time is 8-24 h.

[0010] In the above-mentioned wind turbine gearbox waste lubricating oil regeneration process, during step S4, the adsorbent B is a carbon-based adsorbent with an iodine value of 800-1200 mg / g. The amount of adsorbent B added is 3-8% of the mass of the supernatant. The primary adsorption refining reaction temperature is 80-100℃, the stirring rate is 150-350 r / min, and the reaction time is 0.5-2 h. The outlet pressure of the first pressurizing pump is ≥0.8 MPa. The filtration pressure of the first plate and frame filter is set to 0.8-1.2 MPa. After filtration, the color of the primary adsorption refined oil is significantly reduced, and the acid value is ≤0.05 mg KOH / g.

[0011] In the above-mentioned wind turbine gearbox waste lubricating oil regeneration process, during step S5, the adsorbent C is a silicon-based adsorbent with a particle size distribution of 200-325 mesh; the temperature of the secondary adsorption refining reaction is 80-100℃, the stirring rate is 150-350 r / min, and the reaction time is 0.5-2 h; the outlet pressure of the second pressurizing pump is ≥0.8 MPa; the filtration pressure of the second plate and frame filter is set to 0.8-1.2 MPa; the acid value of the secondary adsorption refined oil obtained after filtration, i.e., the regenerated base oil, is ≤0.02 mg KOH / g, the acid ester color is not greater than 0.5, and the kinematic viscosity change rate at 40℃ is ≤5%.

[0012] The regeneration process for waste lubricating oil in wind turbine gearboxes of the present invention has the following beneficial effects: 1. By employing an ionic liquid pretreatment agent A, which combines deacidification, flocculation, and sedimentation functions, for pretreatment, and further removing residual impurities using highly efficient carbon-based adsorbent B and silicon-based adsorbent C, the waste oil is thoroughly cleaned of deteriorated additives, moisture, acidic oxides, wear metals, and trace residual impurities, resulting in high-quality regenerated oil. This invention's regeneration process features thorough impurity removal, high purity of the regenerated base oil, high regeneration yield, and low equipment investment. It not only possesses significant technical value but also provides strong support for cost reduction and efficiency improvement in the domestic wind power industry, achieving resource recycling. Furthermore, it effectively reduces waste oil pollution, supporting the sustainable development of the wind power industry.

[0013] 2. The devices used in the regeneration process of this invention, such as metal wire mesh filter devices, closed pretreatment tanks, and plate and frame filters, are all commonly used industrial equipment that are easy to obtain and maintain. At the same time, the process parameters can be flexibly adjusted according to the actual processing volume and the quality of the waste lubricating oil, making them highly adaptable and easy to promote and apply in industrial applications. Detailed Implementation

[0014] The regeneration process for waste lubricating oil in wind turbine gearboxes of the present invention includes the following steps: S1. Preliminary filtration to remove large mechanical impurities Waste lubricating oil is filtered using a 40-80 mesh, preferably 60 mesh, metal wire mesh filter to trap and remove large mechanical impurities with a particle size ≥ 40 mesh from the waste lubricating oil, thus obtaining pre-filtered oil.

[0015] S2, Closed-loop heating nitrogen stripping dehydration The pre-filtered oil obtained in step S1 is pumped into a closed pretreatment tank. The heating device inside the pretreatment tank is activated to raise the oil temperature to 100-150℃, preferably 120℃. Simultaneously, nitrogen gas with a purity ≥99.5% is introduced from the bottom of the pretreatment tank for stripping and dehydration. The stripping rate is controlled at 0.5-2m / s. 3Heating is continued at a rate of / h until the moisture content in the initially filtered oil is ≤0.03%. Heating and nitrogen introduction are then stopped to obtain dehydrated waste oil. S3, Pretreatment agent reaction and static sedimentation Keep the pretreatment tank sealed, start the agitator inside the pretreatment tank, and control the stirring speed to 100-300 r / min to stir the dehydrated waste oil obtained in step S2. Simultaneously, slowly add pretreatment agent A from the top feed port of the pretreatment tank at a rate of 0.1-0.5 kg / min. Pretreatment agent A is a mixture containing alkylammonium hydroxylate and imidazole carboxylate; the molecular weight of the alkylammonium hydroxylate is 300-500, and the molecular weight of the imidazole carboxylate is 180-220. The ratio is 2-8:8-2; pretreatment agent A has the functions of deacidification, flocculation and impurity removal and sedimentation; the amount of pretreatment agent A added is 0.8-2% of the mass of the dehydrated waste oil, preferably 1.5%, and the mixture is stirred and reacted for 5-30 minutes, preferably 10 minutes; after the reaction is completed, the stirring paddle is stopped, the reaction mixture is pumped into a settling tank, and the mixture is allowed to settle naturally at 25-40℃ for 8-48 hours. After the solid and liquid are completely separated, the residue is separated from the bottom slag discharge port of the settling tank, and the upper clear liquid in the settling tank is collected at the same time. S4, Primary Adsorption Refining and Filtration The supernatant obtained in step S3 is pumped into a primary adsorption refining reactor with a heating jacket. The stirring device inside the reactor is started (stirring speed 150-350 r / min) and heated. After the temperature inside the reactor rises to 80-100℃, adsorbent B is added to the reactor. Adsorbent B is a carbon-based adsorbent with an iodine value of 800-1200 mg / g. The amount of adsorbent B added is 5% of the mass of the supernatant. The adsorption refining reaction is carried out at a temperature of 80-100℃ and a stirring speed of 1 hour. After the reaction is completed, the reaction mixture is transported to the inlet of the first plate and frame filter press through a first pressurization pump with an outlet pressure ≥0.8 MPa. Filtration is carried out at a filtration pressure of 0.8-1.2 MPa to retain the adsorbent residue and obtain the primary adsorbed refined oil.

[0016] S5, Secondary Adsorption Refining and Filtration The primary adsorption refined oil obtained in step 4 is pumped into a secondary adsorption refined reactor with a heating jacket. The stirring device in the secondary adsorption refined reactor is started (stirring speed 150-350 r / min) and heated. After the temperature in the secondary adsorption refined reactor rises to 80-100℃, adsorbent C is added to the secondary adsorption refined reactor. Adsorbent C is a silica-based adsorbent with a particle size distribution of 200-325 mesh. The amount of adsorbent C added is 1-6% of the mass of the primary adsorption refined oil, preferably 2%. The adsorption refined reaction is carried out at a temperature of 80-100℃ and a stirring speed for 0.5-2 hours, preferably 1 hour. After the reaction is completed, the reaction mixture is transported to a second plate and frame filter press through a second pressurized pump with an outlet pressure ≥0.8MPa. Filtration is carried out at a filtration pressure of 0.8-1.2MPa to retain the adsorbent residue and obtain the secondary adsorption refined oil, i.e., the regenerated base oil.

[0017] After the waste lubricating oil from wind turbine gearboxes is regenerated through the above five steps, the yield of the regenerated base oil is ≥80%, the acid value of the regenerated base oil is ≤0.02mgKOH / g, the color is not greater than 0.5, the kinematic viscosity change rate at 40℃ is ≤5%, the metal content is significantly reduced, and the main indicators all meet the requirements of relevant standards for regenerated base oil.

[0018] The properties of the regenerated base oil obtained after adopting the regeneration process of the waste lubricating oil of the wind turbine gearbox of the present invention are compared with those of the waste lubricating oil of the wind turbine gearbox as shown in Table 1 below.

[0019] Table 1 Comparison of properties of waste gear oil and recycled base oil from wind power plants The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A regeneration process for waste lubricating oil from wind turbine gearboxes, characterized in that, The regeneration process includes the following steps: S1. Pass the waste lubricating oil into a metal wire mesh filter to trap and remove large mechanical impurities with a particle size ≥40 mesh from the waste lubricating oil, and obtain preliminary filtered oil. S2. Pump the preliminary filtered oil obtained in step S1 into a closed pretreatment tank, start the heating device in the pretreatment tank to raise the oil temperature, and at the same time, introduce nitrogen gas with a purity of ≥99.5% from the bottom of the pretreatment tank for stripping and dehydration until the water content in the preliminary filtered oil is ≤0.03%. Stop heating and introducing nitrogen gas to obtain dehydrated waste oil. S3. Keep the pretreatment tank sealed, start the agitator in the pretreatment tank to stir the dehydrated waste oil obtained in step S2, and slowly add pretreatment agent A from the top feed port of the pretreatment tank. The amount of pretreatment agent A added is 0.8-3% of the mass of the dehydrated waste oil. The agitator continues to stir so that the pretreatment agent A reacts with the dehydrated waste oil. After the reaction is completed, the agitator stops stirring and the reaction mixture is pumped into the settling tank. The mixture settles naturally in the settling tank. After the solid and liquid phases of the reaction mixture are completely separated, the residue is separated from the bottom slag discharge port of the settling tank, and the clear liquid in the settling tank is collected at the same time. S4. Pump the supernatant obtained in step S3 into a primary adsorption refining reactor with a heating jacket. Start the stirring device in the primary adsorption refining reactor and heat it. After the temperature in the primary adsorption refining reactor rises, add adsorbent B to the primary adsorption refining reactor. The amount of adsorbent B added is 3-8% of the mass of the supernatant. Maintain the temperature and stirring rate to allow adsorbent B to carry out the adsorption refining reaction with the supernatant. After the reaction is completed, the reaction mixture is transported to the first plate and frame filter press through the first pressurization pump. Filter the mixture in the first plate and frame filter press to retain the adsorbent residue and obtain the primary adsorbed refined oil. S5. Pump the primary adsorption refined oil obtained in step S4 into a secondary adsorption refined reactor with a heating jacket. Start the stirring device in the secondary adsorption refined reactor and heat it. After the temperature in the secondary adsorption refined reactor rises, add adsorbent C to the secondary adsorption refined reactor. The amount of adsorbent C added is 1-6% of the mass of the primary adsorption refined oil. Maintain the temperature and stirring rate to allow the adsorbent C to undergo an adsorption and refining reaction with the primary adsorption refined oil. After the reaction is completed, the reaction mixture is transported to the inlet of the second plate and frame filter press through the second pressurized pump. Filter the mixture in the second plate and frame filter press to retain the adsorbent residue and obtain the regenerated base oil.

2. The waste lubricating oil regeneration process for wind turbine gearboxes according to claim 1, characterized in that, In step S1, the metal mesh in the metal mesh filter device is 40-80 mesh; the material of the metal mesh is 304 stainless steel or 316L stainless steel; the metal mesh filter device is equipped with a backwashing port, and the backwashing is performed every 50-100m... 3 After the waste oil is removed, it is backwashed.

3. The waste lubricating oil regeneration process for wind turbine gearboxes according to claim 1, characterized in that, In step S2, the heating and dehydration temperature is 100-150℃, and the nitrogen stripping rate is 0.5-2m / s. 3 / h, the criterion for determining the dehydration endpoint is: the displayed value of the moisture detector at the gas phase outlet at the top of the pretreatment tank is ≤0.03%.

4. The waste lubricating oil regeneration process for wind turbine gearboxes according to claim 1, characterized in that, In step S3, the pretreatment agent A is a mixture containing alkylammonium hydroxylate and imidazole carboxylate; the molecular weight of the alkylammonium hydroxylate is 300-500, the molecular weight of the imidazole carboxylate is 180-220, and the mixing ratio of the alkylammonium hydroxylate and the imidazole carboxylate is 2-8:8-2; the addition rate of pretreatment agent A is 0.1-0.5 kg / min; the amount of pretreatment agent A added is 0.8-2% of the mass of the dehydrated waste oil; the stirring speed of the agitator in the pretreatment tank is 100-300 r / min; the reaction time is 5-30 minutes; the temperature for natural settling in the static settling tank is 30-50℃; and the settling time is 8-24 h.

5. The waste lubricating oil regeneration process for wind turbine gearboxes according to claim 1, characterized in that, In step S4, the adsorbent B is a carbon-based adsorbent with an iodine value of 800-1200 mg / g. The amount of adsorbent B added is 3-8% of the mass of the supernatant. The primary adsorption purification reaction temperature is 80-100℃, the stirring rate is 150-350 r / min, and the reaction time is 0.5-2 h. The outlet pressure of the first pressurizing pump is ≥0.8 MPa. The filtration pressure of the first plate and frame filter is set to 0.8-1.2 MPa. After filtration, the color of the primary adsorption purified oil is significantly reduced, and the acid value is ≤0.05 mg KOH / g.

6. The waste lubricating oil regeneration process for wind turbine gearboxes according to claim 1, characterized in that, In step S5, the adsorbent C is a silicon-based adsorbent with a particle size distribution of 200-325 mesh; the temperature of the secondary adsorption refining reaction is 80-100℃, the stirring rate is 150-350 r / min, and the reaction time is 0.5-2 h; the outlet pressure of the second pressurizing pump is ≥0.8 MPa; the filtration pressure of the second plate and frame filter is set to 0.8-1.2 MPa; the acid value of the secondary adsorption refined oil obtained after filtration, i.e., the regenerated base oil, is ≤0.02 mg KOH / g, the acid ester color is not greater than 0.5, and the kinematic viscosity change rate at 40℃ is ≤5%.

Images