Method for producing distillation-free biodiesel from high-acid-value waste oil

Abstract

The invention discloses a method for producing distillation-free biodiesel from high-acid-value waste oil and fat, which comprises the following steps: degumming and removing metal ions from the high-acid-value waste oil and fat to obtain degummed and metal ion-removed oil and fat; carrying out dehydration and low-boiling-point removal on the degummed and metal ion-removed grease to obtain dehydrated and low-boiling-point-removed grease; carrying out glyceride esterification deacidification on the dehydrated and low-boiling-point-removed grease to obtain deacidified grease; carrying out transesterification on the deacidified oil and methanol under the action of a base catalyst to obtain crude fatty acid methyl ester; dealcoholizing the crude fatty acid methyl ester to obtain dealcoholized crude fatty acid methyl ester; washing the dealcoholized crude fatty acid methyl ester to obtain desoaped crude fatty acid methyl ester; and dehydrating the de-soaped crude fatty acid methyl ester to obtain the distillation-free biodiesel. The production method is simple and low in energy consumption, the fatty acid methyl ester content of the obtained biodiesel is larger than or equal to 96.5%, and the yield of the biodiesel is 98% or above.

Description

Technical Field

[0001] The present application relates to the technical field of biodiesel, and in particular to a method for producing distillation-free biodiesel from waste oils and fats with high acid value. Background Art

[0002] Biodiesel is made from animal and vegetable oils and fats as raw materials and can be used to replace mineral diesel as a clean fuel for compression ignition engines. The quality of biodiesel is closely related to the fatty acid methyl ester content in biodiesel. Biodiesel requires that the fatty acid methyl ester content must reach 96.5% or more. In order to increase the fatty acid methyl ester content in biodiesel, crude biodiesel is often required to be distilled and refined. Distillation and refining is a very energy-consuming step that can significantly reduce the yield. Its main purpose is to ensure that the fatty acid methyl ester content in biodiesel meets the standard requirements. With the continuous advancement of science and technology, the production technology of biodiesel has been continuously innovated and improved. New process technologies and more advanced separation technologies will help improve the production efficiency of biodiesel, reduce production costs, and improve product quality. Distillation-free biodiesel is biodiesel obtained by omitting the distillation step in the traditional biodiesel production process. Compared with traditional processes, the distillation-free method of producing biodiesel has the advantages of simplifying the production process, reducing production costs, reducing energy consumption, and significantly increasing the yield of biodiesel. Internationally, distillation-free biodiesel generally uses refined vegetable oils (salad oil) as raw materials. However, waste oil raw materials have complex composition, high impurity content and dark color, and general technology cannot produce distillation-free biodiesel. At present, there is no report on the production of distillation-free biodiesel based on waste oil raw materials.

[0003] The base catalysis method is a widely used method for producing biodiesel at home and abroad. The base catalysis method can obtain a higher yield at a lower temperature, but it has higher requirements for the content of free fatty acids and water in the raw materials. In actual production, it is often required that the lower the acid value of the oil, the better. The higher the acid value, the greater the amount of catalyst used, the more fatty acid soaps are generated by the neutralization and saponification reaction, and the amount of fatty acid methyl esters carried and lost increases simultaneously. The preparation of biodiesel using high acid value waste oil as raw material is a major trend in the development of the biodiesel industry. High acid value waste oil raw materials have high acid value and impurity content. When using them as raw materials for the production of biodiesel based on the base catalysis method, the raw materials must first be pretreated to reduce their acid value, moisture content and impurity content. However, the current biodiesel produced from high acid value waste oil raw materials still requires a complex and energy-intensive distillation process to control the fatty acid methyl ester content to above 96.5%, and the biodiesel yield is extremely low.

[0004] Therefore, there is an urgent need to provide a method for producing distillation-free biodiesel from high-acid value waste oils and fats, so as to significantly increase the yield of biodiesel and reduce its energy consumption. Summary of the invention

[0005] The purpose of this application is to overcome the above-mentioned technical deficiencies, propose a method for producing distillation-free biodiesel from high-acid-value waste oil, and solve the technical problem in the prior art that high fatty acid methyl ester content and high yield cannot be achieved in producing distillation-free biodiesel from high-acid-value waste oil.

[0006] The present application provides a method for producing distillation-free biodiesel from waste oil with high acid value, comprising the following steps: Degumming and removing metal ions from waste oil with high acid value to obtain degummed and metal ion-free oil; Dehydrating and removing low boiling points from degummed and metal ion-removed grease to obtain dehydrated and low boiling points-removed grease; The dehydrated and low-boiling oil is subjected to glycerol esterification and deacidification to obtain deacidified oil; The deacidified oil and methanol are subjected to transesterification reaction under the action of an alkali catalyst to obtain crude fatty acid methyl ester; Dealcoholizing the crude fatty acid methyl ester to obtain dealcoholized crude fatty acid methyl ester; washing the dealcoholized crude fatty acid methyl ester to obtain desoaped crude fatty acid methyl ester; The desoaped crude fatty acid methyl ester is dehydrated to obtain distillation-free biodiesel.

[0007] Compared with the prior art, the beneficial effects of this application include: The present application sequentially degummed, demetallated, dehydrated, and de-low-boiling waste oils and fats with high acid value, thereby reducing metal ions, colloids, and moisture in the waste oils and fats with high acid value, and facilitating subsequent treatment; the present application deacidified the dehydrated and de-low-boiling oils and fats by glycerol esterification, thereby converting the fatty acids in the dehydrated and de-low-boiling oils and fats into fatty acid glycerides, thereby avoiding the saponification reaction of the fatty acids with the alkali during the subsequent transesterification reaction, which causes the quality of biodiesel to decrease, and can significantly improve the yield of biodiesel; the present application can convert the deacidified oils and fats into crude fatty acid methyl esters through transesterification, and finally obtain distillation-free biodiesel through simple dealcoholization, washing, and dehydration. The production method of the present application is simple and has low energy consumption. The fatty acid methyl ester content of the obtained biodiesel is ≥96.5%, and the biodiesel yield is above 98%. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 This is a process flow chart of an embodiment of a method for producing distillation-free biodiesel from high-acid value waste oil provided in the present application. DETAILED DESCRIPTION

[0009] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0010] See also Figure 1 The present application provides a method for producing distillation-free biodiesel from waste oil with high acid value, comprising the following steps: S1, degumming and removing metal ions from high acid value waste oil to obtain degummed and metal ion-removed oil; S2, dehydrating and removing low boiling points from the degummed and metal ion-removed grease to obtain dehydrated and low boiling points grease; S3, glycerol esterification and deacidification of the dehydrated and low-boiling oil to obtain deacidified oil; S4, subjecting the deacidified oil and methanol to an ester exchange reaction under the action of an alkali catalyst to obtain crude fatty acid methyl ester; S5, dealcoholizing the crude fatty acid methyl ester to obtain dealcoholized crude fatty acid methyl ester; S6, washing the dealcoholized crude fatty acid methyl ester to obtain desoaped crude fatty acid methyl ester; S7, dehydrating the desoaped crude fatty acid methyl ester to obtain distillation-free biodiesel.

[0011] The present application sequentially degummed, demetallated, dehydrated, and de-low-boiling waste oils and fats with high acid value, thereby reducing metal ions, colloids, and moisture in the waste oils and fats with high acid value, and facilitating subsequent treatment; the present application deacidified the dehydrated and de-low-boiling oils and fats by glycerol esterification, thereby converting the fatty acids in the dehydrated and de-low-boiling oils and fats into fatty acid glycerides, thereby avoiding the saponification reaction of the fatty acids with the alkali during the subsequent transesterification reaction, which causes the quality of biodiesel to decrease, and can significantly improve the yield of biodiesel; the present application can convert the deacidified oils and fats into crude fatty acid methyl esters through transesterification, and finally obtain distillation-free biodiesel through simple dealcoholization, washing, and dehydration. The production method of the present application is simple and has low energy consumption. The fatty acid methyl ester content of the obtained biodiesel is ≥96.5%, and the biodiesel yield is above 98%.

[0012] In this embodiment, in step S1, the acid value of the high acid value waste oil is ≤100 mg KOH / g. The present application does not limit the type of high acid value waste oil, and those skilled in the art can select it according to actual conditions. For example, the high acid value waste oil can be hogwash oil, acidified oil, high acid palm crude oil, etc.

[0013] In some more specific embodiments of the present application, the acid value of the high-acid-value waste oil is ≤100 mg KOH / g, the sulfur content is ≤35 ppm, and the unsaponifiable matter content is ≤1%.

[0014] In this embodiment, in step S1, the total metal ion content of the degummed and demetallized oil is ≤10ppm, wherein the phosphorus content is ≤3ppm.

[0015] The present application does not limit the process of degumming and demetallization, and those skilled in the art can make a choice according to the actual situation. In some specific embodiments of the present application, the process of degumming and demetallization includes: degumming and demetallization of high acid value waste oil and fat using oxalic acid and citric acid, followed by a first heat preservation sedimentation separation to obtain degummed and demetallized oil and fat. Among them, the amount of oxalic acid added is 0.1%-1.0% of the mass of high acid value waste oil and fat, including but not limited to 0.1%, 0.2%, 0.4%, 0.6%, 0.8%, 1% and the like; the amount of citric acid added is 0.1%-1.0% of the mass of high acid value waste oil and fat, including but not limited to 0.1%, 0.2%, 0.4%, 0.6%, 0.8%, 1% and the like; oxalic acid and citric acid are added in the form of an aqueous solution, and the amount of the aqueous solution of oxalic acid and citric acid added is 3%-10% of the mass of high acid value waste oil and fat, including but not limited to 3%, 4%, 5%, 6%, 7%, 8%, 9% and the like. %, 10%, etc.; the temperature for degumming and metal ion removal is 80-100°C, including but not limited to 80°C, 85°C, 90°C, 95°C, 100°C, etc.; the time for degumming and metal ion removal is 10-90 minutes, including but not limited to 10 minutes, 30 minutes, 50 minutes, 70 minutes, 90 minutes, etc.; the temperature for the first heat preservation sedimentation separation is 80-100°C, including but not limited to 80°C, 85°C, 90°C, 95°C, 100°C, etc.; the time for the first heat preservation sedimentation separation is 2-10 hours, including but not limited to 2 hours, 4 hours, 6 hours, 8 hours, 10 hours, etc. The present application uses oxalic acid and citric acid to degumming and metal ion removal treatment of high acid value waste oil, and cooperates with the above-mentioned process parameters to control the total metal ion content of degummed and metal ion-removed oil to within 10ppm, and the phosphorus content to within 3ppm.

[0016] In this embodiment, in step S2, the water content of the dehydrated and low-boiling oil is ≤0.3%, preferably ≤0.1%.

[0017] The present application does not limit the process of dehydration and de-low boiling, and those skilled in the art can choose according to actual conditions. In some specific embodiments of the present application, vacuum dehydration and de-low boiling are adopted. Wherein, the temperature of vacuum dehydration and de-low boiling is 70-120°C, including but not limited to 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, etc.; the vacuum residual pressure is 6000-15000Pa, including but not limited to 6000Pa, 7000Pa, 8000Pa, 9000Pa, 10000Pa, 11000Pa, 12000Pa, 13000Pa, 14000Pa, 15000Pa, etc.; the time of vacuum dehydration and de-low boiling is 10-90 minutes, including but not limited to 10 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes, 60 minutes, 70 minutes, 80 minutes, 90 minutes, etc. By adopting the above-mentioned process parameters, the present application can control the water content of dehydrated and low-boiling oils and fats to within 0.3%.

[0018] In this embodiment, in step S3, the acid value of the deacidified oil is ≤1 mg KOH / g. By reducing the acid value of the deacidified oil to within 1 mg KOH / g, the present application is more conducive to the smooth progress of the subsequent transesterification reaction and increases the fatty acid methyl ester content.

[0019] In this embodiment, in step S3, a triglyceride esterification reaction is used for deacidification.

[0020] Among them, during the primary glycerol esterification reaction, the amount of glycerol added is 10%-13% of the mass of dehydrated and low-boiling oil, including but not limited to 10%, 11%, 12%, 13%, etc.; the temperature of the primary glycerol esterification reaction is 180-200°C, including but not limited to 180°C, 185°C, 190°C, 195°C, 200°C, etc.; the vacuum residual pressure of the primary glycerol esterification reaction is 8000-15000Pa, including but not limited to 8000Pa, 9000Pa, 10000Pa, 11000Pa, 12000Pa, 13000Pa, 14000Pa, 15000Pa, etc. By adopting the above process parameters, the present application can control the acid value of the primary glycerol esterification product within 25 mg KOH / g.

[0021] Among them, during the secondary glycerol esterification reaction, the amount of glycerol added is 1%-3% of the mass of dehydrated and low-boiling oil, including but not limited to 1%, 2%, 3%, etc.; the temperature of the secondary glycerol esterification reaction is 200-220°C, including but not limited to 200°C, 205°C, 210°C, 215°C, 220°C, etc.; the vacuum residual pressure of the secondary glycerol esterification reaction is 5000-8000Pa, including but not limited to 5000Pa, 5500Pa, 6000Pa, 6500Pa, 7000Pa, 7500Pa, 8000Pa, etc. By adopting the above process parameters, the present application can control the acid value of the secondary glycerol esterification product within 5 mg KOH / g.

[0022] Among them, during the three-stage glycerol esterification reaction, the amount of glycerol added is 0%-2% of the mass of the dehydrated and low-boiling oil, including but not limited to 0%, 1%, 2%, etc.; the temperature of the three-stage esterification reaction is 220-245°C, including but not limited to 220°C, 225°C, 230°C, 235°C, 240°C, 245°C, etc.; the vacuum residual pressure of the three-stage esterification reaction is 500-1500Pa, including but not limited to 500Pa, 700Pa, 900Pa, 1100Pa, 1300Pa, 1500Pa, etc. By adopting the above process parameters, the present application can control the acid value of the three-stage esterification product within 1 mg KOH / g.

[0023] The time for each stage of esterification reaction is 1-4 hours, including but not limited to 1 hour, 2 hours, 3 hours, 4 hours, etc.

[0024] The present application adopts a three-stage glycerol esterification reaction and cooperates with the above-mentioned process parameters to promote the esterification reaction and reduce the by-products produced by glycerol polymerization and the evaporation loss of glycerol, and ultimately control the acid value of the deacidified oil and fat within 1 mg KOH / g, improve the yield, and reduce the amount of glycerol used.

[0025] In this embodiment, in step S4, the base catalyst is at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium methoxide, potassium methoxide, and calcium hydroxide.

[0026] In this embodiment, in step S4, the amount of the alkaline catalyst added is 0.3%-0.5% of the mass of the deacidified oil, including but not limited to 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, etc.

[0027] In this embodiment, in step S4, the amount of methanol added is 20%-35% of the mass of the deacidified oil, including but not limited to 20%, 22%, 25%, 28%, 30%, 32%, 35%, etc.

[0028] In this embodiment, in step S4, the temperature of the ester exchange reaction is 56-66°C, including but not limited to 56°C, 58°C, 60°C, 62°C, 64°C, 66°C, etc.; the time of the ester exchange reaction is 1-9 hours, including but not limited to 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, etc.

[0029] In this embodiment, in step S4, after the transesterification reaction is completed, a second heat preservation sedimentation separation is also performed. Specifically, the temperature of the second heat preservation sedimentation separation is 56-66°C, including but not limited to 56°C, 58°C, 60°C, 62°C, 64°C, 66°C, etc.; the time of the second heat preservation sedimentation separation is 1-9 hours, including but not limited to 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, etc.

[0030] In some preferred embodiments of the present application, a tertiary transesterification reaction is adopted.

[0031] Among them, during the primary ester exchange reaction, the amount of alkaline catalyst added is 0.25%-0.4% of the mass of the deacidified oil, including but not limited to 0.25%, 0.28%, 0.3%, 0.32%, 0.35%, 0.38%, 0.4% and the like; the amount of methanol added is 18%-25% of the mass of the deacidified oil, including but not limited to 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25% and the like.

[0032] Among them, during the secondary transesterification reaction, the amount of alkaline catalyst added is 0.05%-0.10% of the mass of the deacidified oil, including but not limited to 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.10% and the like; the amount of methanol added is 1%-5% of the mass of the deacidified oil, including but not limited to 1%, 2%, 3%, 4%, 5% and the like.

[0033] Among them, during the tertiary ester exchange reaction, the amount of alkaline catalyst added is 0.05%-0.10% of the mass of deacidified oil and fat, including but not limited to 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.10% and the like; the amount of methanol added is 1%-5% of the mass of deacidified oil and fat, including but not limited to 1%, 2%, 3%, 4%, 5% and the like.

[0034] Among them, the temperature of each stage of ester exchange reaction is 56-66°C, including but not limited to 56°C, 58°C, 60°C, 62°C, 64°C, 66°C, etc.; the time of each stage of ester exchange reaction is 1-3 hours, including but not limited to 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, etc.

[0035] After the ester exchange reaction at each stage is completed, the second heat preservation sedimentation separation is carried out. Specifically, the temperature of the second heat preservation sedimentation separation at each stage is 56-66°C, including but not limited to 56°C, 58°C, 60°C, 62°C, 64°C, 66°C, etc.; the time of the second heat preservation sedimentation separation at each stage is 1-3 hours, including but not limited to 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, etc.

[0036] The base catalysis method can produce biodiesel with high yield at a lower temperature. In order to make the reaction more sufficient, a large amount of catalyst and methanol are often added. However, due to the introduction of a large amount of alkali and methanol, it will not only cause a waste of raw materials, but also cause subsequent separation difficulties. The present application adopts a three-stage transesterification reaction, and adds the base catalyst and alcohol in sections, and cooperates with the above-mentioned process parameters. The triglyceride residue in the fatty acid methyl ester can be controlled within 0.2%, the diglyceride residue is controlled within 0.2%, and the monoglyceride residue is controlled within 0.7%, and the amount of the base catalyst and alcohol is reduced, so as to avoid the difficulty of subsequent removal of the base catalyst and alcohol due to the excessive amount of the base catalyst and alcohol, and the loss of fatty acid methyl ester caused during the removal process, thereby improving the fatty acid methyl ester content and yield of biodiesel.

[0037] More preferably, the crude glycerol obtained from the secondary transesterification reaction is returned to the primary transesterification reaction, the crude glycerol obtained from the tertiary transesterification reaction is returned to the secondary transesterification reaction, and the crude glycerol obtained from the primary transesterification reaction is processed separately.

[0038] In this embodiment, in step S5, the alcohol residue in the dealcoholized crude fatty acid methyl ester is less than 0.1%.

[0039] The present application does not limit the method of dealcoholization, and those skilled in the art can choose according to actual conditions. In some specific embodiments of the present application, a vacuum dealcoholization method is adopted. Among them, the temperature of vacuum dealcoholization is 80-100°C, including but not limited to 80°C, 85°C, 90°C, 95°C, 100°C, etc.; the vacuum residual pressure is 8000-15000Pa, including but not limited to 8000Pa, 9000Pa, 10000Pa, 11000Pa, 12000Pa, 13000Pa, 14000Pa, 15000Pa, etc.; the time of vacuum dealcoholization is 30-90 minutes, including but not limited to 30 minutes, 40 minutes, 50 minutes, 60 minutes, 70 minutes, 80 minutes, 90 minutes, etc. The present application can control the alcohol residue in the dealcoholized crude fatty acid methyl ester to within 0.1% by adopting the method of vacuum dealcoholization and cooperating with the above-mentioned process parameters.

[0040] In this embodiment, in step S6, the soap residue in the desoaped crude fatty acid methyl ester is less than 50 ppm.

[0041] The present application does not limit the washing method, and those skilled in the art can choose according to actual conditions. In some specific embodiments of the present application, washing is carried out by water washing, followed by separation by the third heat preservation sedimentation to obtain desoaped crude fatty acid methyl ester. Wherein, the amount of water added is 5%-10% of the mass of the dealcoholized fatty acid methyl ester, including but not limited to 5%, 6%, 7%, 8%, 9%, 10%, etc.; the washing temperature is 80-100°C, including but not limited to 80°C, 85°C, 90°C, 95°C, 100°C, etc.; the washing time is 15-30 minutes, including but not limited to 15 minutes, 17 minutes, 20 minutes, 22 minutes, 25 minutes, 28 minutes, 30 minutes, etc.; the temperature of the third heat preservation sedimentation separation is 80-100°C, including but not limited to 80°C, 85°C, 90°C, 95°C, 100°C, etc.; the time of the third heat preservation sedimentation separation is 2-4 hours, including but not limited to 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, etc. The present application can effectively remove glycerol, triglycerides, diglycerides, monoglycerol fatty acid esters and soaps in crude biodiesel by adopting a water washing method and cooperating with the above-mentioned process parameters, and control the soap residue in the desoaped crude fatty acid methyl ester to less than 50 ppm.

[0042] In this embodiment, in step S7, the residual water in the non-distillation biodiesel is less than 0.1%.

[0043] The present application does not limit the dehydration method, and those skilled in the art can choose according to actual conditions. In some specific embodiments of the present application, a vacuum dehydration method is adopted. Among them, the temperature of vacuum dehydration is 90-120°C, including but not limited to 90°C, 100°C, 110°C, 120°C, etc.; the vacuum residual pressure is 3000-5000Pa, including but not limited to 3000Pa, 3500Pa, 40000Pa, 4500Pa, 5000Pa, etc.; the time of vacuum dehydration is 30-90 minutes, including but not limited to 30 minutes, 40 minutes, 50 minutes, 60 minutes, 70 minutes, 80 minutes, 90 minutes, etc. The present application adopts the method of vacuum dehydration and cooperates with the above-mentioned process parameters to control the water residue in the crude fatty acid methyl ester obtained after dehydration to within 0.1%.

[0044] Example 1 (1) Degumming and metal ion removal Add 1000g of high-acid palm crude oil with an acid value of 98 mg KOH / g, a sulfur content of 25ppm, and unsaponifiable matter of 0.7% to a 2000ml three-necked flask. Install a stirrer and a thermometer, and slowly heat the electric bowl under stirring conditions. When the temperature reaches 85°C, add a mixed acid solution of 5% by weight of the oil, and in the mixed acid solution, oxalic acid is 0.3% by weight of the oil, and citric acid is 0.3% by weight of the oil. Maintain stirring at 85°C for 30 minutes, pour into a heat-insulating separatory funnel, keep at 85°C for 6 hours, and remove the phospholipid gel solution at the bottom. The clear oil is tested for phosphorus according to ASTM D5185-18, and the test result shows that the phosphorus is 2ppm.

[0045] (2) Vacuum dehydration and low boiling point removal Pour the clear oil into a 2000ml three-necked flask, install a stirrer and a thermometer, and slowly heat the electric heating bowl under stirring. Turn on the water ring vacuum pump, control the vacuum residual pressure to 12000Pa, the solution temperature to 120℃, and dehydrate for 20 minutes. According to ISO662, the water content of the solution was tested, and the water content test result was 0.15%.

[0046] (3) Glycerol esterification and deacidification Primary glycerol esterification reaction: add dehydrated and low-boiling oil to a 2000ml three-necked flask, install a stirrer and a thermometer, heat the electric heating bowl slowly under stirring, turn on the water ring vacuum pump, control the vacuum residual pressure to 12000Pa, add 12% glycerol by weight, start timing at 200℃, and react for 2 hours. Sample and test the acid value according to GB / T5530, and the acid value test result is 18.2 mg KOH / g.

[0047] Secondary glycerol esterification reaction: Replace the mechanical vacuum pump, control the vacuum residual pressure to 6000Pa, add glycerol with a weight of 2% of the oil, adjust the temperature control to 220℃, maintain the temperature and stir for 2 hours. According to GB / T5530, sample and test the acid value, and the acid value test result is 2.82 mg KOH / g.

[0048] Triglyceride esterification reaction: adjust the vacuum residual pressure to 600Pa, adjust the control temperature to 245℃, and continue the reaction for 2 hours. Test the acid value according to GB / T5530, and the acid value test result is 0.4 mg KOH / g.

[0049] (4) Base-catalyzed transesterification Primary transesterification reaction: Add oil with an acid value of 0.4 mg KOH / g to a 2000 ml three-necked flask, install a stirrer and a thermometer, and slowly heat the electric bowl under stirring. When the temperature reaches 65°C, add a mixed solution containing 0.25% potassium hydroxide by weight of the oil and 20% methanol by weight of the oil. Maintain stirring at 65°C for 2 hours, pour into a heat-insulating separatory funnel, keep warm at 65°C for 2 hours, remove the crude glycerol solution at the bottom, and the crude methyl ester enters the secondary transesterification reaction.

[0050] Secondary transesterification reaction: Add the crude methyl ester from the primary reaction into a 2000ml three-necked flask, install a stirrer and a thermometer, and slowly heat the electric bowl under stirring. When the temperature reaches 65°C, add a mixed solution containing 0.05% potassium hydroxide by weight and 3% methanol by weight of oil, and maintain stirring at 65°C for 2 hours. Pour the mixture into an insulated separating funnel, and keep it at 65°C for 2 hours to separate by sedimentation. Remove the crude glycerol solution at the bottom, and the crude methyl ester enters the tertiary transesterification reaction, and the crude glycerol returns to the primary transesterification reaction.

[0051] Tertiary transesterification reaction: Add the secondary reaction crude methyl ester to a 2000ml three-necked flask, install a stirrer and a thermometer, and slowly heat the electric heating bowl under stirring conditions. When the temperature reaches 65°C, add a pre-prepared mixed solution containing 0.05% potassium hydroxide by weight of oil and 3% methanol by weight of oil, maintain 65°C stirring reaction for 2 hours, pour into a heat-insulating separatory funnel, keep 65°C for sedimentation separation for 2 hours, remove the bottom crude glycerol solution, and return the crude glycerol to the secondary transesterification reaction. According to EN14105, the target requirement for crude fatty acid methyl ester is less than 0.2% for triglycerides, and the test result is less than 0.1%; the target requirement for diglycerides is less than 0.2%, and the test result is less than 0.1%; the target requirement for monoglycerol fatty acid ester content is less than 0.7%, and the test result is 0.43%. Qualified crude fatty acid methyl ester enters the vacuum dealcoholization process.

[0052] (5) Vacuum dealcoholization Pour the crude fatty acid methyl ester into a 2000ml three-necked flask, install a stirrer and a thermometer, and slowly heat the electric heating bowl under stirring conditions. Turn on the water ring vacuum pump, control the vacuum residual pressure to 12000Pa, the solution temperature to 95℃, and dealcoholize for 60 minutes. According to ISO662, the methanol content was tested and the methanol content test result was 0.10%.

[0053] (6) Washing Pour the dealcoholized fatty acid methyl ester into a 2000ml three-necked flask, install a stirrer and a thermometer, and slowly heat the electric heating bowl under stirring conditions. When the temperature reaches 95°C, add distilled water that is 10% of the weight of the methyl ester and stir and wash for 30 minutes. Pour it into a heat-insulating separatory funnel, keep it at 85°C for 4 hours, and remove the wastewater solution at the bottom. The soap content of fatty acid methyl ester is tested according to GB / T5533, and the soap residue test result is 27ppm.

[0054] (7) Vacuum dehydration Fatty acid methyl ester was poured into a 2000ml three-necked flask, equipped with a stirrer and a thermometer. Under stirring conditions, the electric heating bowl was heated slowly, the water ring vacuum pump was turned on, the vacuum residual pressure was controlled to be 5000Pa, the solution temperature was 120℃, and dehydration was performed for 60 minutes to obtain 992 grams of fatty acid methyl ester (biodiesel). The water content of the solution was tested according to ISO662, and the water content was 0.02%; the fatty acid methyl ester content was tested according to EN14103, and the test result was 96.9%; the total glycerol content was tested according to EN14105, and the test result was 0.22%; the sulfur content was tested according to SH / T0689, and the test result was 8.5ppm; the acid value was tested according to GB / T5530, and the test result was 0.3 mg KOH / g.

[0055] Example 2 The raw material oil is 1000 g of high-acid crude palm oil with an acid value of 72 mg KOH / g, a sulfur content of 21 ppm, and an unsaponifiable matter content of 0.4%. The dehydrated and low-boiling oil obtained after treatment according to steps (1) and (2) of Example 1 is treated by the following steps (3) and (4): (3) Glycerol esterification and deacidification Primary glycerol esterification reaction: add dehydrated and low-boiling oil to a 2000ml three-necked flask, install a stirrer and a thermometer, heat the electric heating bowl slowly under stirring, turn on the water ring vacuum pump, control the vacuum residual pressure to 15000Pa, add glycerol with a weight of 10% of the oil, start timing at 180℃, and react for 1 hour. Sample and test the acid value according to GB / T5530, and the acid value test result is 15.7 mg KOH / g.

[0056] Secondary glycerol esterification reaction: replace the mechanical vacuum pump, control the vacuum residual pressure to 5000Pa, add glycerol with a weight of 2% of the oil, adjust the temperature control to 200℃, maintain the temperature and stir for 1 hour. According to GB / T5530, sample and test the acid value, and the acid value test result is 4.02 mg KOH / g.

[0057] Triglyceride esterification reaction: adjust the vacuum residual pressure to 500Pa, adjust the temperature to 220℃, and continue the reaction for 1 hour. Test the acid value according to GB / T5530, and the acid value test result is 0.8 mg KOH / g.

[0058] (4) Base-catalyzed transesterification Primary transesterification reaction: Add oil with an acid value of 0.8 mg KOH / g to a 2000 ml three-necked flask, install a stirrer and a thermometer, and slowly heat the electric bowl under stirring. When the temperature reaches 60°C, add a mixed solution containing 0.30% potassium hydroxide by weight of oil and 18% methanol by weight of oil. Maintain stirring at 60°C for 3 hours, pour into a heat-insulating separating funnel, keep at 60°C for 3 hours, remove the crude glycerol solution at the bottom, and the crude methyl ester enters the secondary transesterification reaction.

[0059] Secondary transesterification reaction: Add the crude methyl ester from the primary reaction into a 2000ml three-necked flask, install a stirrer and a thermometer, and slowly heat the electric bowl under stirring. When the temperature reaches 60°C, add a mixed solution containing 0.10% potassium hydroxide by weight of oil and 5% methanol by weight of oil, maintain stirring at 60°C for 3 hours, pour into an insulated separating funnel, keep at 60°C for sedimentation and separation for 3 hours, remove the crude glycerol solution at the bottom, and the crude methyl ester enters the tertiary transesterification reaction, and the crude glycerol returns to the primary transesterification reaction.

[0060] Tertiary transesterification reaction: Add the crude methyl ester of the secondary reaction into a 2000ml three-necked flask, install a stirrer and a thermometer, and slowly heat the electric heating bowl under stirring conditions. When the temperature reaches 60°C, add a pre-prepared mixed solution containing 0.10% potassium hydroxide by weight of oil and 5% methanol by weight of oil, maintain stirring at 60°C for 3 hours, pour into a heat-insulating separatory funnel, keep warm at 60°C for 3 hours, remove the crude glycerol solution at the bottom, and return the crude glycerol to the secondary transesterification reaction. The target requirement for crude fatty acid methyl esters is less than 0.2% for triglycerides according to EN14105, and the test result is less than 0.1%; the target requirement for diglycerides is less than 0.2%, and the test result is 0.12%; the target requirement for monoglycerol fatty acid ester content is less than 0.7%, and the test result is 0.57%.

[0061] The crude fatty acid methyl ester was treated by steps (5) to (7) of Example 1 to obtain 987 g of biodiesel. The water content of the solution was tested according to ISO662, and the water content was 0.05%. The fatty acid methyl ester content was tested according to EN14103, and the test result was 96.8%. The total glycerol content was tested according to EN14105, and the test result was 0.19%. The sulfur content was tested according to SH / T0689, and the test result was 9.6 ppm. The acid value was tested according to GB / T5530, and the test result was 0.3 mg KOH / g.

[0062] Example 3 The raw material oil is 1000 g of high-acid crude palm oil with an acid value of 91 mg KOH / g, a sulfur content of 28 ppm, and an unsaponifiable matter content of 0.6%. The dehydrated and low-boiling oil obtained after treatment according to steps (1) and (2) of Example 1 is treated by the following steps (3) and (4): (3) Glycerol esterification and deacidification Primary glycerol esterification reaction: add dehydrated and low-boiling oil to a 2000ml three-necked flask, install a stirrer and a thermometer, heat the electric heating bowl slowly under stirring, turn on the water ring vacuum pump, control the vacuum residual pressure to 8000Pa, add 13% glycerol by weight, start timing at 190℃, and react for 3 hours. Sample and test the acid value according to GB / T5530, and the acid value test result is 19.4 mg KOH / g.

[0063] Secondary glycerol esterification reaction: Replace the mechanical vacuum pump, control the vacuum residual pressure to 8000Pa, add glycerol with a weight of 2% of the oil, adjust the temperature control to 210℃, maintain the temperature and stir for 3 hours. According to GB / T5530, sample and test the acid value, and the acid value test result is 3.16 mg KOH / g.

[0064] Triglyceride esterification reaction: adjust the vacuum residual pressure to 1500Pa, adjust the control temperature to 230°C, and continue the reaction for 3 hours. According to GB / T5530, the acid value was tested and the acid value test result was 0.7 mg KOH / g.

[0065] (4) Base-catalyzed transesterification Primary transesterification reaction: Add oil with an acid value of 0.7 mg KOH / g to a 2000 ml three-necked flask, install a stirrer and a thermometer, and slowly heat the electric bowl under stirring. When the temperature reaches 65°C, add a mixed solution containing 0.30% potassium hydroxide by weight of oil and 22% methanol by weight of oil. Maintain stirring at 65°C for 1 hour, pour into a heat-insulating separatory funnel, keep at 65°C for 1 hour, remove the crude glycerol solution at the bottom, and the crude methyl ester enters the secondary transesterification reaction.

[0066] Secondary transesterification reaction: add the crude methyl ester from the primary reaction into a 2000ml three-necked flask, install a stirrer and a thermometer, and slowly heat the electric bowl under stirring. When the temperature reaches 65°C, add a mixed solution containing 0.05% potassium hydroxide by weight and 1% methanol by weight. Maintain stirring at 65°C for 1 hour, pour into a heat-insulating separating funnel, keep at 65°C for 1 hour, remove the crude glycerol solution at the bottom, and the crude methyl ester enters the tertiary transesterification reaction, and the crude glycerol returns to the primary transesterification reaction.

[0067] Tertiary transesterification reaction: Add the crude methyl ester of the secondary reaction into a 2000ml three-necked flask, install a stirrer and a thermometer, and slowly heat the electric heating bowl under stirring conditions. When the temperature reaches 65°C, add a mixed solution containing 0.05% potassium hydroxide by weight of oil and 1% methanol by weight of oil, maintain 65°C for stirring and reaction for 1 hour, pour into a heat-insulating separatory funnel, keep it at 65°C for sedimentation and separation for 1 hour, remove the crude glycerol solution at the bottom, and return the crude glycerol to the secondary transesterification reaction. The target requirement for crude fatty acid methyl esters is less than 0.2% for triglycerides according to EN14105, and the test result is less than 0.1%; the target requirement for diglycerides is less than 0.2%, and the test result is 0.17%; the target requirement for monoglycerol fatty acid ester content is less than 0.7%, and the test result is 0.65%.

[0068] The crude fatty acid methyl ester was treated by steps (5) to (7) of Example 1 to obtain 981 g of biodiesel. The water content of the solution was tested according to ISO662, and the water content was 0.03%. The fatty acid methyl ester content was tested according to EN14103, and the test result was 96.5%. The total glycerol content was tested according to EN14105, and the test result was 0.21%. The sulfur content was tested according to SH / T0689, and the test result was 9.2 ppm. The acid value was tested according to GB / T5530, and the test result was 0.35 mg KOH / g.

[0069] Comparative Example 1 Compared with Example 1, the only difference is that step (4) is adjusted as follows: Primary transesterification reaction: Add oil with an acid value of 0.4 mg KOH / g to a 2000 ml three-necked flask, install a stirrer and a thermometer, and slowly heat the electric bowl under stirring. When the temperature reaches 65°C, add a mixed solution containing 0.35% potassium hydroxide by weight of oil and 26% methanol by weight of oil. Maintain stirring at 65°C for 2 hours, pour into a heat-insulating separating funnel, keep at 65°C for 2 hours, remove the crude glycerol solution at the bottom, and the crude methyl ester enters the secondary transesterification reaction.

[0070] Secondary transesterification reaction: Add the crude methyl ester from the primary reaction into a 2000ml three-necked flask, install a stirrer and a thermometer, and slowly heat the electric bowl under stirring conditions. When the temperature reaches 65°C, maintain the stirring reaction at 65°C for 2 hours, pour it into an insulated separating funnel, keep it at 65°C for 2 hours, remove the crude glycerol solution at the bottom, and the crude methyl ester enters the tertiary transesterification reaction, and the crude glycerol returns to the primary transesterification reaction.

[0071] Tertiary ester exchange reaction: Add the crude methyl ester from the secondary reaction into a 2000ml three-necked flask, install a stirrer and a thermometer, and slowly heat the electric bowl under stirring. When the temperature reaches 65°C, maintain stirring at 65°C for 2 hours, then pour into a heat-insulating separating funnel, keep at 65°C for 2 hours, and remove the crude glycerol solution at the bottom.

[0072] The crude fatty acid methyl ester was treated by steps (5) to (7) of Example 1 to obtain 958 g of biodiesel. The water content was detected according to ISO662, and the water content was 0.03%. The fatty acid methyl ester content was detected according to EN14103, and the test result was 96.1%. The total glycerol content was detected according to EN14105, and the test result was 0.32%. The sulfur content was detected according to SH / T0689, and the test result was 8.7 ppm. The acid value was detected according to GB / T5530, and the test result was 0.4 mg KOH / g.

[0073] In summary, the present application produces distillation-free biodiesel by sequentially degumming, removing metal ions, dehydrating, removing low boiling points, esterification deacidification, ester exchange reaction, dealcoholization, washing and dehydrating high acid value waste oils, and the method is simple and has low energy consumption; the fatty acid methyl ester content in the biodiesel produced by the present application is controlled to be above 96.5%, the sulfur content is controlled within 15ppm, and the total glycerol content is controlled within 0.25%; by adopting the above steps and further cooperating with the process parameters of the present application, the present application can obtain high-quality biodiesel with a fatty acid methyl ester content of above 96.5%, while controlling the yield of biodiesel to above 98%.

[0074] The specific implementation methods of the present application described above do not constitute a limitation on the protection scope of the present application. Any other corresponding changes and modifications made according to the technical concept of the present application should be included in the protection scope of the claims of the present application.

Claims

1. A method for producing distillation-free biodiesel from waste oils with high acid value, characterized in that: The following steps are involved: Degumming and removing metal ions from waste oil with high acid value to obtain degummed and metal ion-removed oil; Dehydrating and removing low boiling points from the degummed and metal ion-removed oil to obtain dehydrated and low boiling points-removed oil; The dehydrated and low-boiling oil is subjected to glycerol esterification and deacidification to obtain deacidified oil; The deacidified oil and methanol are subjected to an ester exchange reaction under the action of an alkali catalyst to obtain crude fatty acid methyl ester; Dealcoholizing the crude fatty acid methyl ester to obtain dealcoholized crude fatty acid methyl ester; washing the dealcoholized crude fatty acid methyl ester to obtain desoaped crude fatty acid methyl ester; The desoaped crude fatty acid methyl ester is dehydrated to obtain distillation-free biodiesel.

2. The method for producing distillation-free biodiesel from waste oil with high acid value according to claim 1, characterized in that: The acid value of the high acid value waste oil is ≤100 mg KOH / g, the sulfur content is ≤35 ppm, and the unsaponifiable matter content is ≤1%; and / or, The total metal ion content of the degummed and demetallized grease is ≤10ppm, wherein the phosphorus content is ≤3ppm; and / or, The water content of the dehydrated and low-boiling oil is ≤0.3%; and / or, The acid value of the deacidified oil is ≤1 mg KOH / g; and / or, The alcohol residue in the dealcoholized crude fatty acid methyl ester is less than 0.1%; and / or, The soap residue in the desoaped crude fatty acid methyl ester is less than 50 ppm; and / or, The water residue in the distillation-free biodiesel is less than 0.1%.

3. The method for producing distillation-free biodiesel from waste oil with high acid value according to claim 1, characterized in that: The degumming and metal ion removal process comprises: using oxalic acid and citric acid to degumming and metal ion removal the high acid value waste oil, and then performing a first heat preservation sedimentation separation to obtain degummed and metal ion-free oil; wherein, The amount of oxalic acid added is 0.1%-1.0% of the mass of the high acid value waste oil; and / or, The amount of citric acid added is 0.1%-1.0% of the mass of the high acid value waste oil; and / or, The oxalic acid and the citric acid are added in the form of an aqueous solution, and the amount of the aqueous solution of the oxalic acid and the citric acid added is 3%-10% of the mass of the high acid value waste oil; and / or, The temperature of degumming and demetallization is 80-100°C, and the time of degumming and demetallization is 10-90 minutes; and / or, The temperature of the first heat preservation sedimentation separation is 80-100° C., and the time of the first heat preservation sedimentation separation is 2-10 hours.

4. The method for producing distillation-free biodiesel from waste oils with high acid value according to claim 1, characterized in that: The degummed and metal ion-free grease is subjected to vacuum dehydration and low boiling point removal; wherein, The temperature of the vacuum dehydration and low boiling point removal is 70-120° C., the vacuum residual pressure is 6000-15000 Pa, and the time of the vacuum dehydration and low boiling point removal is 10-90 minutes.

5. The method for producing distillation-free biodiesel from waste oil with high acid value according to claim 1, characterized in that: The deacidification is carried out by esterification reaction of triglyceride; wherein, During the primary glycerol esterification reaction, the amount of glycerol added is 10%-13% of the mass of the dehydrated and low-boiling oil; the temperature of the primary glycerol esterification reaction is 180-200° C., the vacuum residual pressure of the primary glycerol esterification reaction is 8000-15000 Pa, and the time of the primary esterification reaction is 1-4 hours; and / or, During the secondary glycerol esterification reaction, the amount of glycerol added is 1%-3% of the mass of the dehydrated and low-boiling oil; the temperature of the secondary glycerol esterification reaction is 200-220° C., the vacuum residual pressure of the secondary glycerol esterification reaction is 5000-8000 Pa, and the time of the secondary esterification reaction is 1-4 hours; and / or, During the tertiary glycerol esterification reaction, the amount of glycerol added is 0%-2% of the mass of the dehydrated and low-boiling oil; the temperature of the tertiary esterification reaction is 220-245°C, the vacuum residual pressure of the tertiary esterification reaction is 500-1500Pa, and the time of the tertiary esterification reaction is 1-4 hours.

6. The method for producing distillation-free biodiesel from waste oil with high acid value according to claim 1, characterized in that: The alkaline catalyst is at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium methoxide, potassium methoxide, and calcium hydroxide; and / or, The amount of the alkaline catalyst added is 0.3%-0.5% of the mass of the deacidified oil; and / or, The amount of methanol added is 20%-35% of the mass of the deacidified oil; and / or, The temperature of the transesterification reaction is 56-66° C., and the time of the transesterification reaction is 1-9 hours; and / or, After the transesterification reaction is completed, a second heat preservation sedimentation separation is performed, and the temperature of the second heat preservation sedimentation separation is 56-66° C., and the time of the second heat preservation sedimentation separation is 1-9 hours.

7. The method for producing distillation-free biodiesel from waste oils with high acid value according to claim 6, characterized in that: A three-stage transesterification reaction is used; wherein, During the primary transesterification reaction, the amount of the base catalyst added is 0.25%-0.4% of the mass of the deacidified oil, and the amount of the methanol added is 18%-25% of the mass of the deacidified oil; and / or, During the secondary transesterification reaction, the amount of the base catalyst added is 0.05%-0.10% of the mass of the deacidified oil, and the amount of the methanol added is 1%-5% of the mass of the deacidified oil; and / or, During the tertiary transesterification reaction, the amount of the base catalyst added is 0.05%-0.10% of the mass of the deacidified oil, and the amount of the methanol added is 1%-5% of the mass of the deacidified oil; The temperature of each level of transesterification reaction is 56-66°C, and the time of each level of transesterification reaction is 1-3 hours; After the ester exchange reaction at each stage is completed, the second heat preservation sedimentation separation is carried out, and the temperature of the second heat preservation sedimentation separation at each stage is 56-66° C., and the time of the second heat preservation sedimentation separation at each stage is 1-3 hours.

8. The method for producing distillation-free biodiesel from waste oils with high acid value according to claim 1, characterized in that: The crude fatty acid methyl ester is subjected to vacuum dealcoholization; wherein, The temperature of the vacuum dealcoholization is 80-100° C., the vacuum residual pressure is 8000-15000 Pa, and the time of the vacuum dealcoholization is 30-90 minutes.

9. The method for producing distillation-free biodiesel from waste oils with high acid value according to claim 1, characterized in that: The product is washed with water, and then separated by a third heat preservation sedimentation to obtain desoaped crude fatty acid methyl ester; wherein: The amount of water added is 5%-10% of the mass of the dealcoholized fatty acid methyl ester; and / or, The washing temperature is 80-100°C, and the washing time is 15-30 minutes; and / or, The temperature of the third thermal insulation sedimentation separation is 80-100° C., and the time of the third thermal insulation sedimentation separation is 2-4 hours.

10. The method for producing distillation-free biodiesel from waste oils with high acid value according to claim 1, characterized in that: The desoaped crude fatty acid methyl ester is subjected to vacuum dehydration; wherein, The temperature of the vacuum dehydration is 90-120° C., the vacuum residual pressure is 3000-5000 Pa, and the time of the vacuum dehydration is 30-90 minutes.

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